Add m-esr52 at 52.6.0

978 files changed, 191912 insertions, 0 deletions

diff --git a/xpcom/base/AvailableMemoryTracker.cpp b/xpcom/base/AvailableMemoryTracker.cpp
new file mode 100644
index 000000000..6272d89cf
--- /dev/null
+++ b/xpcom/base/AvailableMemoryTracker.cpp
@@ -0,0 +1,447 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/AvailableMemoryTracker.h"
+
+#if defined(XP_WIN)
+#include "prinrval.h"
+#include "prenv.h"
+#include "nsIMemoryReporter.h"
+#include "nsMemoryPressure.h"
+#endif
+
+#include "nsIObserver.h"
+#include "nsIObserverService.h"
+#include "nsIRunnable.h"
+#include "nsISupports.h"
+#include "nsThreadUtils.h"
+
+#include "mozilla/Preferences.h"
+#include "mozilla/Services.h"
+
+#if defined(XP_WIN)
+#   include "nsWindowsDllInterceptor.h"
+#   include <windows.h>
+#endif
+
+#if defined(MOZ_MEMORY)
+#   include "mozmemory.h"
+#endif  // MOZ_MEMORY
+
+using namespace mozilla;
+
+namespace {
+
+#if defined(_M_IX86) && defined(XP_WIN)
+
+
+uint32_t sLowVirtualMemoryThreshold = 0;
+uint32_t sLowCommitSpaceThreshold = 0;
+uint32_t sLowPhysicalMemoryThreshold = 0;
+uint32_t sLowMemoryNotificationIntervalMS = 0;
+
+Atomic<uint32_t> sNumLowVirtualMemEvents;
+Atomic<uint32_t> sNumLowCommitSpaceEvents;
+Atomic<uint32_t> sNumLowPhysicalMemEvents;
+
+WindowsDllInterceptor sKernel32Intercept;
+WindowsDllInterceptor sGdi32Intercept;
+
+// Has Init() been called?
+bool sInitialized = false;
+
+// Has Activate() been called?  The hooks don't do anything until this happens.
+bool sHooksActive = false;
+
+// Alas, we'd like to use mozilla::TimeStamp, but we can't, because it acquires
+// a lock!
+volatile bool sHasScheduledOneLowMemoryNotification = false;
+volatile PRIntervalTime sLastLowMemoryNotificationTime;
+
+// These are function pointers to the functions we wrap in Init().
+
+void* (WINAPI* sVirtualAllocOrig)(LPVOID aAddress, SIZE_T aSize,
+                                  DWORD aAllocationType, DWORD aProtect);
+
+void* (WINAPI* sMapViewOfFileOrig)(HANDLE aFileMappingObject,
+                                   DWORD aDesiredAccess, DWORD aFileOffsetHigh,
+                                   DWORD aFileOffsetLow, SIZE_T aNumBytesToMap);
+
+HBITMAP(WINAPI* sCreateDIBSectionOrig)(HDC aDC, const BITMAPINFO* aBitmapInfo,
+                                       UINT aUsage, VOID** aBits,
+                                       HANDLE aSection, DWORD aOffset);
+
+/**
+ * Fire a memory pressure event if it's been long enough since the last one we
+ * fired.
+ */
+bool
+MaybeScheduleMemoryPressureEvent()
+{
+  // If this interval rolls over, we may fire an extra memory pressure
+  // event, but that's not a big deal.
+  PRIntervalTime interval = PR_IntervalNow() - sLastLowMemoryNotificationTime;
+  if (sHasScheduledOneLowMemoryNotification &&
+      PR_IntervalToMilliseconds(interval) < sLowMemoryNotificationIntervalMS) {
+
+    return false;
+  }
+
+  // There's a bit of a race condition here, since an interval may be a
+  // 64-bit number, and 64-bit writes aren't atomic on x86-32.  But let's
+  // not worry about it -- the races only happen when we're already
+  // experiencing memory pressure and firing notifications, so the worst
+  // thing that can happen is that we fire two notifications when we
+  // should have fired only one.
+  sHasScheduledOneLowMemoryNotification = true;
+  sLastLowMemoryNotificationTime = PR_IntervalNow();
+
+  NS_DispatchEventualMemoryPressure(MemPressure_New);
+  return true;
+}
+
+void
+CheckMemAvailable()
+{
+  if (!sHooksActive) {
+    return;
+  }
+
+  MEMORYSTATUSEX stat;
+  stat.dwLength = sizeof(stat);
+  bool success = GlobalMemoryStatusEx(&stat);
+
+  if (success) {
+    // sLowVirtualMemoryThreshold is in MB, but ullAvailVirtual is in bytes.
+    if (stat.ullAvailVirtual < sLowVirtualMemoryThreshold * 1024 * 1024) {
+      // If we're running low on virtual memory, unconditionally schedule the
+      // notification.  We'll probably crash if we run out of virtual memory,
+      // so don't worry about firing this notification too often.
+      ++sNumLowVirtualMemEvents;
+      NS_DispatchEventualMemoryPressure(MemPressure_New);
+    } else if (stat.ullAvailPageFile < sLowCommitSpaceThreshold * 1024 * 1024) {
+      if (MaybeScheduleMemoryPressureEvent()) {
+        ++sNumLowCommitSpaceEvents;
+      }
+    } else if (stat.ullAvailPhys < sLowPhysicalMemoryThreshold * 1024 * 1024) {
+      if (MaybeScheduleMemoryPressureEvent()) {
+        ++sNumLowPhysicalMemEvents;
+      }
+    }
+  }
+}
+
+LPVOID WINAPI
+VirtualAllocHook(LPVOID aAddress, SIZE_T aSize,
+                 DWORD aAllocationType,
+                 DWORD aProtect)
+{
+  // It's tempting to see whether we have enough free virtual address space for
+  // this allocation and, if we don't, synchronously fire a low-memory
+  // notification to free some before we allocate.
+  //
+  // Unfortunately that doesn't work, principally because code doesn't expect a
+  // call to malloc could trigger a GC (or call into the other routines which
+  // are triggered by a low-memory notification).
+  //
+  // I think the best we can do here is try to allocate the memory and check
+  // afterwards how much free virtual address space we have.  If we're running
+  // low, we schedule a low-memory notification to run as soon as possible.
+
+  LPVOID result = sVirtualAllocOrig(aAddress, aSize, aAllocationType, aProtect);
+
+  // Don't call CheckMemAvailable for MEM_RESERVE if we're not tracking low
+  // virtual memory.  Similarly, don't call CheckMemAvailable for MEM_COMMIT if
+  // we're not tracking low physical memory.
+  if ((sLowVirtualMemoryThreshold != 0 && aAllocationType & MEM_RESERVE) ||
+      (sLowPhysicalMemoryThreshold != 0 && aAllocationType & MEM_COMMIT)) {
+    CheckMemAvailable();
+  }
+
+  return result;
+}
+
+LPVOID WINAPI
+MapViewOfFileHook(HANDLE aFileMappingObject,
+                  DWORD aDesiredAccess,
+                  DWORD aFileOffsetHigh,
+                  DWORD aFileOffsetLow,
+                  SIZE_T aNumBytesToMap)
+{
+  LPVOID result = sMapViewOfFileOrig(aFileMappingObject, aDesiredAccess,
+                                     aFileOffsetHigh, aFileOffsetLow,
+                                     aNumBytesToMap);
+  CheckMemAvailable();
+  return result;
+}
+
+HBITMAP WINAPI
+CreateDIBSectionHook(HDC aDC,
+                     const BITMAPINFO* aBitmapInfo,
+                     UINT aUsage,
+                     VOID** aBits,
+                     HANDLE aSection,
+                     DWORD aOffset)
+{
+  // There are a lot of calls to CreateDIBSection, so we make some effort not
+  // to CheckMemAvailable() for calls to CreateDIBSection which allocate only
+  // a small amount of memory.
+
+  // If aSection is non-null, CreateDIBSection won't allocate any new memory.
+  bool doCheck = false;
+  if (sHooksActive && !aSection && aBitmapInfo) {
+    uint16_t bitCount = aBitmapInfo->bmiHeader.biBitCount;
+    if (bitCount == 0) {
+      // MSDN says bitCount == 0 means that it figures out how many bits each
+      // pixel gets by examining the corresponding JPEG or PNG data.  We'll just
+      // assume the worst.
+      bitCount = 32;
+    }
+
+    // |size| contains the expected allocation size in *bits*.  Height may be
+    // negative (indicating the direction the DIB is drawn in), so we take the
+    // absolute value.
+    int64_t size = bitCount * aBitmapInfo->bmiHeader.biWidth *
+                              aBitmapInfo->bmiHeader.biHeight;
+    if (size < 0) {
+      size *= -1;
+    }
+
+    // If we're allocating more than 1MB, check how much memory is left after
+    // the allocation.
+    if (size > 1024 * 1024 * 8) {
+      doCheck = true;
+    }
+  }
+
+  HBITMAP result = sCreateDIBSectionOrig(aDC, aBitmapInfo, aUsage, aBits,
+                                         aSection, aOffset);
+
+  if (doCheck) {
+    CheckMemAvailable();
+  }
+
+  return result;
+}
+
+static int64_t
+LowMemoryEventsVirtualDistinguishedAmount()
+{
+  return sNumLowVirtualMemEvents;
+}
+
+static int64_t
+LowMemoryEventsPhysicalDistinguishedAmount()
+{
+  return sNumLowPhysicalMemEvents;
+}
+
+class LowEventsReporter final : public nsIMemoryReporter
+{
+  ~LowEventsReporter() {}
+
+public:
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override
+  {
+    MOZ_COLLECT_REPORT(
+      "low-memory-events/virtual", KIND_OTHER, UNITS_COUNT_CUMULATIVE,
+      LowMemoryEventsVirtualDistinguishedAmount(),
+"Number of low-virtual-memory events fired since startup. We fire such an "
+"event if we notice there is less than memory.low_virtual_mem_threshold_mb of "
+"virtual address space available (if zero, this behavior is disabled). The "
+"process will probably crash if it runs out of virtual address space, so "
+"this event is dire.");
+
+    MOZ_COLLECT_REPORT(
+      "low-memory-events/commit-space", KIND_OTHER, UNITS_COUNT_CUMULATIVE,
+      sNumLowCommitSpaceEvents,
+"Number of low-commit-space events fired since startup. We fire such an "
+"event if we notice there is less than memory.low_commit_space_threshold_mb of "
+"commit space available (if zero, this behavior is disabled). Windows will "
+"likely kill the process if it runs out of commit space, so this event is "
+"dire.");
+
+    MOZ_COLLECT_REPORT(
+      "low-memory-events/physical", KIND_OTHER, UNITS_COUNT_CUMULATIVE,
+      LowMemoryEventsPhysicalDistinguishedAmount(),
+"Number of low-physical-memory events fired since startup. We fire such an "
+"event if we notice there is less than memory.low_physical_memory_threshold_mb "
+"of physical memory available (if zero, this behavior is disabled).  The "
+"machine will start to page if it runs out of physical memory.  This may "
+"cause it to run slowly, but it shouldn't cause it to crash.");
+
+    return NS_OK;
+  }
+};
+NS_IMPL_ISUPPORTS(LowEventsReporter, nsIMemoryReporter)
+
+#endif // defined(_M_IX86) && defined(XP_WIN)
+
+/**
+ * This runnable is executed in response to a memory-pressure event; we spin
+ * the event-loop when receiving the memory-pressure event in the hope that
+ * other observers will synchronously free some memory that we'll be able to
+ * purge here.
+ */
+class nsJemallocFreeDirtyPagesRunnable final : public nsIRunnable
+{
+  ~nsJemallocFreeDirtyPagesRunnable() {}
+
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIRUNNABLE
+};
+
+NS_IMPL_ISUPPORTS(nsJemallocFreeDirtyPagesRunnable, nsIRunnable)
+
+NS_IMETHODIMP
+nsJemallocFreeDirtyPagesRunnable::Run()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+#if defined(MOZ_MEMORY)
+  jemalloc_free_dirty_pages();
+#endif
+
+  return NS_OK;
+}
+
+/**
+ * The memory pressure watcher is used for listening to memory-pressure events
+ * and reacting upon them. We use one instance per process currently only for
+ * cleaning up dirty unused pages held by jemalloc.
+ */
+class nsMemoryPressureWatcher final : public nsIObserver
+{
+  ~nsMemoryPressureWatcher() {}
+
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+
+  void Init();
+
+private:
+  static bool sFreeDirtyPages;
+};
+
+NS_IMPL_ISUPPORTS(nsMemoryPressureWatcher, nsIObserver)
+
+bool nsMemoryPressureWatcher::sFreeDirtyPages = false;
+
+/**
+ * Initialize and subscribe to the memory-pressure events. We subscribe to the
+ * observer service in this method and not in the constructor because we need
+ * to hold a strong reference to 'this' before calling the observer service.
+ */
+void
+nsMemoryPressureWatcher::Init()
+{
+  nsCOMPtr<nsIObserverService> os = services::GetObserverService();
+
+  if (os) {
+    os->AddObserver(this, "memory-pressure", /* ownsWeak */ false);
+  }
+
+  Preferences::AddBoolVarCache(&sFreeDirtyPages, "memory.free_dirty_pages",
+                               false);
+}
+
+/**
+ * Reacts to all types of memory-pressure events, launches a runnable to
+ * free dirty pages held by jemalloc.
+ */
+NS_IMETHODIMP
+nsMemoryPressureWatcher::Observe(nsISupports* aSubject, const char* aTopic,
+                                 const char16_t* aData)
+{
+  MOZ_ASSERT(!strcmp(aTopic, "memory-pressure"), "Unknown topic");
+
+  if (sFreeDirtyPages) {
+    nsCOMPtr<nsIRunnable> runnable = new nsJemallocFreeDirtyPagesRunnable();
+
+    NS_DispatchToMainThread(runnable);
+  }
+
+  return NS_OK;
+}
+
+} // namespace
+
+namespace mozilla {
+namespace AvailableMemoryTracker {
+
+void
+Activate()
+{
+#if defined(_M_IX86) && defined(XP_WIN)
+  MOZ_ASSERT(sInitialized);
+  MOZ_ASSERT(!sHooksActive);
+
+  Preferences::AddUintVarCache(&sLowVirtualMemoryThreshold,
+                               "memory.low_virtual_mem_threshold_mb", 256);
+  Preferences::AddUintVarCache(&sLowPhysicalMemoryThreshold,
+                               "memory.low_physical_memory_threshold_mb", 0);
+  Preferences::AddUintVarCache(&sLowCommitSpaceThreshold,
+                               "memory.low_commit_space_threshold_mb", 256);
+  Preferences::AddUintVarCache(&sLowMemoryNotificationIntervalMS,
+                               "memory.low_memory_notification_interval_ms",
+                               10000);
+
+  RegisterStrongMemoryReporter(new LowEventsReporter());
+  RegisterLowMemoryEventsVirtualDistinguishedAmount(
+    LowMemoryEventsVirtualDistinguishedAmount);
+  RegisterLowMemoryEventsPhysicalDistinguishedAmount(
+    LowMemoryEventsPhysicalDistinguishedAmount);
+  sHooksActive = true;
+#endif
+
+  // This object is held alive by the observer service.
+  RefPtr<nsMemoryPressureWatcher> watcher = new nsMemoryPressureWatcher();
+  watcher->Init();
+}
+
+void
+Init()
+{
+  // Do nothing on x86-64, because nsWindowsDllInterceptor is not thread-safe
+  // on 64-bit.  (On 32-bit, it's probably thread-safe.)  Even if we run Init()
+  // before any other of our threads are running, another process may have
+  // started a remote thread which could call VirtualAlloc!
+  //
+  // Moreover, the benefit of this code is less clear when we're a 64-bit
+  // process, because we aren't going to run out of virtual memory, and the
+  // system is likely to have a fair bit of physical memory.
+
+#if defined(_M_IX86) && defined(XP_WIN)
+  // Don't register the hooks if we're a build instrumented for PGO: If we're
+  // an instrumented build, the compiler adds function calls all over the place
+  // which may call VirtualAlloc; this makes it hard to prevent
+  // VirtualAllocHook from reentering itself.
+  if (!PR_GetEnv("MOZ_PGO_INSTRUMENTED")) {
+    sKernel32Intercept.Init("Kernel32.dll");
+    sKernel32Intercept.AddHook("VirtualAlloc",
+                               reinterpret_cast<intptr_t>(VirtualAllocHook),
+                               reinterpret_cast<void**>(&sVirtualAllocOrig));
+    sKernel32Intercept.AddHook("MapViewOfFile",
+                               reinterpret_cast<intptr_t>(MapViewOfFileHook),
+                               reinterpret_cast<void**>(&sMapViewOfFileOrig));
+
+    sGdi32Intercept.Init("Gdi32.dll");
+    sGdi32Intercept.AddHook("CreateDIBSection",
+                            reinterpret_cast<intptr_t>(CreateDIBSectionHook),
+                            reinterpret_cast<void**>(&sCreateDIBSectionOrig));
+  }
+
+  sInitialized = true;
+#endif
+}
+
+} // namespace AvailableMemoryTracker
+} // namespace mozilla
diff --git a/xpcom/base/AvailableMemoryTracker.h b/xpcom/base/AvailableMemoryTracker.h
new file mode 100644
index 000000000..33572f9c7
--- /dev/null
+++ b/xpcom/base/AvailableMemoryTracker.h
@@ -0,0 +1,30 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_AvailableMemoryTracker_h
+#define mozilla_AvailableMemoryTracker_h
+
+namespace mozilla {
+namespace AvailableMemoryTracker {
+
+// The AvailableMemoryTracker launches a memory pressure watcher on all
+// platforms to react to low-memory situations and on Windows it implements
+// the full functionality used to monitor how much memory is available.
+//
+// Init() must be called before any other threads have started, because it
+// modifies the in-memory implementations of some DLL functions in
+// non-thread-safe ways.
+//
+// The hooks don't do anything until Activate() is called.  It's an error to
+// call Activate() without first calling Init().
+
+void Init();
+void Activate();
+
+} // namespace AvailableMemoryTracker
+} // namespace mozilla
+
+#endif // ifndef mozilla_AvailableMemoryTracker_h
diff --git a/xpcom/base/ClearOnShutdown.cpp b/xpcom/base/ClearOnShutdown.cpp
new file mode 100644
index 000000000..bfb3142bc
--- /dev/null
+++ b/xpcom/base/ClearOnShutdown.cpp
@@ -0,0 +1,45 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ClearOnShutdown.h"
+
+namespace mozilla {
+namespace ClearOnShutdown_Internal {
+
+Array<StaticAutoPtr<ShutdownList>,
+      static_cast<size_t>(ShutdownPhase::ShutdownPhase_Length)> sShutdownObservers;
+ShutdownPhase sCurrentShutdownPhase = ShutdownPhase::NotInShutdown;
+
+} // namespace ClearOnShutdown_Internal
+
+// Called when XPCOM is shutting down, after all shutdown notifications have
+// been sent and after all threads' event loops have been purged.
+void
+KillClearOnShutdown(ShutdownPhase aPhase)
+{
+  using namespace ClearOnShutdown_Internal;
+
+  MOZ_ASSERT(NS_IsMainThread());
+  // Shutdown only goes one direction...
+  MOZ_ASSERT(static_cast<size_t>(sCurrentShutdownPhase) < static_cast<size_t>(aPhase));
+
+  // It's impossible to add an entry for a "past" phase; this is blocked in
+  // ClearOnShutdown, but clear them out anyways in case there are phases
+  // that weren't passed to KillClearOnShutdown.
+  for (size_t phase = static_cast<size_t>(ShutdownPhase::First);
+       phase <= static_cast<size_t>(aPhase);
+       phase++) {
+    if (sShutdownObservers[static_cast<size_t>(phase)]) {
+      while (ShutdownObserver* observer = sShutdownObservers[static_cast<size_t>(phase)]->popFirst()) {
+        observer->Shutdown();
+        delete observer;
+      }
+      sShutdownObservers[static_cast<size_t>(phase)] = nullptr;
+    }
+  }
+}
+
+} // namespace mozilla
diff --git a/xpcom/base/ClearOnShutdown.h b/xpcom/base/ClearOnShutdown.h
new file mode 100644
index 000000000..5c39c281c
--- /dev/null
+++ b/xpcom/base/ClearOnShutdown.h
@@ -0,0 +1,124 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_ClearOnShutdown_h
+#define mozilla_ClearOnShutdown_h
+
+#include "mozilla/LinkedList.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/Array.h"
+#include "MainThreadUtils.h"
+
+/*
+ * This header exports one public method in the mozilla namespace:
+ *
+ *   template<class SmartPtr>
+ *   void ClearOnShutdown(SmartPtr *aPtr, aPhase=ShutdownPhase::ShutdownFinal)
+ *
+ * This function takes a pointer to a smart pointer and nulls the smart pointer
+ * on shutdown (and a particular phase of shutdown as needed).  If a phase
+ * is specified, the ptr will be cleared at the start of that phase.  Also,
+ * if a phase has already occurred when ClearOnShutdown() is called it will
+ * cause a MOZ_ASSERT.  In case a phase is not explicitly cleared we will
+ * clear it on the next phase that occurs.
+ *
+ * This is useful if you have a global smart pointer object which you don't
+ * want to "leak" on shutdown.
+ *
+ * Although ClearOnShutdown will work with any smart pointer (i.e., nsCOMPtr,
+ * nsRefPtr, nsAutoPtr, StaticRefPtr, and StaticAutoPtr), you probably want to
+ * use it only with StaticRefPtr and StaticAutoPtr.  There is no way to undo a
+ * call to ClearOnShutdown, so you can call it only on smart pointers which you
+ * know will live until the program shuts down.  In practice, these are likely
+ * global variables, which should be Static{Ref,Auto}Ptr.
+ *
+ * ClearOnShutdown is currently main-thread only because we don't want to
+ * accidentally free an object from a different thread than the one it was
+ * created on.
+ */
+
+namespace mozilla {
+
+// Must be contiguous starting at 0
+enum class ShutdownPhase {
+  NotInShutdown = 0,
+  WillShutdown,
+  Shutdown,
+  ShutdownThreads,
+  ShutdownLoaders,
+  ShutdownFinal,
+  ShutdownPhase_Length, // never pass this value
+  First = WillShutdown, // for iteration
+  Last = ShutdownFinal
+};
+
+namespace ClearOnShutdown_Internal {
+
+class ShutdownObserver : public LinkedListElement<ShutdownObserver>
+{
+public:
+  virtual void Shutdown() = 0;
+  virtual ~ShutdownObserver()
+  {
+  }
+};
+
+template<class SmartPtr>
+class PointerClearer : public ShutdownObserver
+{
+public:
+  explicit PointerClearer(SmartPtr* aPtr)
+    : mPtr(aPtr)
+  {
+  }
+
+  virtual void Shutdown() override
+  {
+    if (mPtr) {
+      *mPtr = nullptr;
+    }
+  }
+
+private:
+  SmartPtr* mPtr;
+};
+
+typedef LinkedList<ShutdownObserver> ShutdownList;
+extern Array<StaticAutoPtr<ShutdownList>,
+             static_cast<size_t>(ShutdownPhase::ShutdownPhase_Length)> sShutdownObservers;
+extern ShutdownPhase sCurrentShutdownPhase;
+
+} // namespace ClearOnShutdown_Internal
+
+template<class SmartPtr>
+inline void
+ClearOnShutdown(SmartPtr* aPtr, ShutdownPhase aPhase = ShutdownPhase::ShutdownFinal)
+{
+  using namespace ClearOnShutdown_Internal;
+
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aPhase != ShutdownPhase::ShutdownPhase_Length);
+
+  // Adding a ClearOnShutdown for a "past" phase is an error.
+  if (!(static_cast<size_t>(sCurrentShutdownPhase) < static_cast<size_t>(aPhase))) {
+    MOZ_ASSERT(false, "ClearOnShutdown for phase that already was cleared");
+    *aPtr = nullptr;
+    return;
+  }
+
+  if (!(sShutdownObservers[static_cast<size_t>(aPhase)])) {
+    sShutdownObservers[static_cast<size_t>(aPhase)] = new ShutdownList();
+  }
+  sShutdownObservers[static_cast<size_t>(aPhase)]->insertBack(new PointerClearer<SmartPtr>(aPtr));
+}
+
+// Called when XPCOM is shutting down, after all shutdown notifications have
+// been sent and after all threads' event loops have been purged.
+void KillClearOnShutdown(ShutdownPhase aPhase);
+
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/base/CodeAddressService.h b/xpcom/base/CodeAddressService.h
new file mode 100644
index 000000000..7f91f93a6
--- /dev/null
+++ b/xpcom/base/CodeAddressService.h
@@ -0,0 +1,198 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+* License, v. 2.0. If a copy of the MPL was not distributed with this
+* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef CodeAddressService_h__
+#define CodeAddressService_h__
+
+#include "mozilla/Assertions.h"
+#include "mozilla/HashFunctions.h"
+#include "mozilla/IntegerPrintfMacros.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Types.h"
+
+#include "mozilla/StackWalk.h"
+
+namespace mozilla {
+
+// This class is used to print details about code locations.
+//
+// |StringTable| must implement an Intern() method that returns an interned
+// copy of the string that was passed in, as well as a standard
+// SizeOfExcludingThis() method.
+//
+// |StringAlloc| must implement |copy| and |free|. |copy| copies a string,
+// while |free| is used to free strings created by |copy|.
+//
+// |DescribeCodeAddressLock| is needed when the callers may be holding a lock
+// used by MozDescribeCodeAddress.  |DescribeCodeAddressLock| must implement
+// static methods IsLocked(), Unlock() and Lock().
+template <class StringTable,
+          class StringAlloc,
+          class DescribeCodeAddressLock>
+class CodeAddressService
+{
+  // GetLocation() is the key function in this class.  It's basically a wrapper
+  // around MozDescribeCodeAddress.
+  //
+  // However, MozDescribeCodeAddress is very slow on some platforms, and we
+  // have lots of repeated (i.e. same PC) calls to it.  So we do some caching
+  // of results.  Each cached result includes two strings (|mFunction| and
+  // |mLibrary|), so we also optimize them for space in the following ways.
+  //
+  // - The number of distinct library names is small, e.g. a few dozen.  There
+  //   is lots of repetition, especially of libxul.  So we intern them in their
+  //   own table, which saves space over duplicating them for each cache entry.
+  //
+  // - The number of distinct function names is much higher, so we duplicate
+  //   them in each cache entry.  That's more space-efficient than interning
+  //   because entries containing single-occurrence function names are quickly
+  //   overwritten, and their copies released.  In addition, empty function
+  //   names are common, so we use nullptr to represent them compactly.
+
+  StringTable mLibraryStrings;
+
+  struct Entry
+  {
+    const void* mPc;
+    char*       mFunction;  // owned by the Entry;  may be null
+    const char* mLibrary;   // owned by mLibraryStrings;  never null
+                            //   in a non-empty entry is in use
+    ptrdiff_t   mLOffset;
+    char*       mFileName;  // owned by the Entry; may be null
+    uint32_t    mLineNo:31;
+    uint32_t    mInUse:1;   // is the entry used?
+
+    Entry()
+      : mPc(0), mFunction(nullptr), mLibrary(nullptr), mLOffset(0),
+        mFileName(nullptr), mLineNo(0), mInUse(0)
+    {}
+
+    ~Entry()
+    {
+      // We don't free mLibrary because it's externally owned.
+      StringAlloc::free(mFunction);
+      StringAlloc::free(mFileName);
+    }
+
+    void Replace(const void* aPc, const char* aFunction,
+                 const char* aLibrary, ptrdiff_t aLOffset,
+                 const char* aFileName, unsigned long aLineNo)
+    {
+      mPc = aPc;
+
+      // Convert "" to nullptr.  Otherwise, make a copy of the name.
+      StringAlloc::free(mFunction);
+      mFunction = !aFunction[0] ? nullptr : StringAlloc::copy(aFunction);
+      StringAlloc::free(mFileName);
+      mFileName = !aFileName[0] ? nullptr : StringAlloc::copy(aFileName);
+
+      mLibrary = aLibrary;
+      mLOffset = aLOffset;
+      mLineNo = aLineNo;
+
+      mInUse = 1;
+    }
+
+    size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+    {
+      // Don't measure mLibrary because it's externally owned.
+      size_t n = 0;
+      n += aMallocSizeOf(mFunction);
+      n += aMallocSizeOf(mFileName);
+      return n;
+    }
+  };
+
+  // A direct-mapped cache.  When doing dmd::Analyze() just after starting
+  // desktop Firefox (which is similar to analyzing after a longer-running
+  // session, thanks to the limit on how many records we print), a cache with
+  // 2^24 entries (which approximates an infinite-entry cache) has a ~91% hit
+  // rate.  A cache with 2^12 entries has a ~83% hit rate, and takes up ~85 KiB
+  // (on 32-bit platforms) or ~150 KiB (on 64-bit platforms).
+  static const size_t kNumEntries = 1 << 12;
+  static const size_t kMask = kNumEntries - 1;
+  Entry mEntries[kNumEntries];
+
+  size_t mNumCacheHits;
+  size_t mNumCacheMisses;
+
+public:
+  CodeAddressService()
+    : mEntries(), mNumCacheHits(0), mNumCacheMisses(0)
+  {
+  }
+
+  void GetLocation(uint32_t aFrameNumber, const void* aPc, char* aBuf,
+                   size_t aBufLen)
+  {
+    MOZ_ASSERT(DescribeCodeAddressLock::IsLocked());
+
+    uint32_t index = HashGeneric(aPc) & kMask;
+    MOZ_ASSERT(index < kNumEntries);
+    Entry& entry = mEntries[index];
+
+    if (!entry.mInUse || entry.mPc != aPc) {
+      mNumCacheMisses++;
+
+      // MozDescribeCodeAddress can (on Linux) acquire a lock inside
+      // the shared library loader.  Another thread might call malloc
+      // while holding that lock (when loading a shared library).  So
+      // we have to exit the lock around this call.  For details, see
+      // https://bugzilla.mozilla.org/show_bug.cgi?id=363334#c3
+      MozCodeAddressDetails details;
+      {
+        DescribeCodeAddressLock::Unlock();
+        (void)MozDescribeCodeAddress(const_cast<void*>(aPc), &details);
+        DescribeCodeAddressLock::Lock();
+      }
+
+      const char* library = mLibraryStrings.Intern(details.library);
+      entry.Replace(aPc, details.function, library, details.loffset,
+                    details.filename, details.lineno);
+
+    } else {
+      mNumCacheHits++;
+    }
+
+    MOZ_ASSERT(entry.mPc == aPc);
+
+    MozFormatCodeAddress(aBuf, aBufLen, aFrameNumber, entry.mPc,
+                         entry.mFunction, entry.mLibrary, entry.mLOffset,
+                         entry.mFileName, entry.mLineNo);
+  }
+
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    size_t n = aMallocSizeOf(this);
+    for (uint32_t i = 0; i < kNumEntries; i++) {
+      n += mEntries[i].SizeOfExcludingThis(aMallocSizeOf);
+    }
+
+    n += mLibraryStrings.SizeOfExcludingThis(aMallocSizeOf);
+
+    return n;
+  }
+
+  size_t CacheCapacity() const { return kNumEntries; }
+
+  size_t CacheCount() const
+  {
+    size_t n = 0;
+    for (size_t i = 0; i < kNumEntries; i++) {
+      if (mEntries[i].mInUse) {
+        n++;
+      }
+    }
+    return n;
+  }
+
+  size_t NumCacheHits()   const { return mNumCacheHits; }
+  size_t NumCacheMisses() const { return mNumCacheMisses; }
+};
+
+} // namespace mozilla
+
+#endif // CodeAddressService_h__
diff --git a/xpcom/base/CountingAllocatorBase.h b/xpcom/base/CountingAllocatorBase.h
new file mode 100644
index 000000000..fb4d2ffe8
--- /dev/null
+++ b/xpcom/base/CountingAllocatorBase.h
@@ -0,0 +1,140 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef CountingAllocatorBase_h
+#define CountingAllocatorBase_h
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Atomics.h"
+#include "nsIMemoryReporter.h"
+
+namespace mozilla {
+
+// This CRTP class handles several details of wrapping allocators and should
+// be preferred to manually counting with MOZ_DEFINE_MALLOC_SIZE_OF_ON_ALLOC
+// and MOZ_DEFINE_MALLOC_SIZE_OF_ON_FREE.  The typical use is in a memory
+// reporter for a particular third party library:
+//
+//   class MyMemoryReporter : public CountingAllocatorBase<MyMemoryReporter>
+//   {
+//     ...
+//     NS_IMETHOD
+//     CollectReports(nsIHandleReportCallback* aHandleReport,
+//                    nsISupports* aData, bool aAnonymize) override
+//     {
+//        MOZ_COLLECT_REPORT(
+//          "explicit/path/to/somewhere", KIND_HEAP, UNITS_BYTES,
+//          MemoryAllocated(),
+//          "A description of what we are reporting.");
+//
+//        return NS_OK;
+//     }
+//   };
+//
+//   ...somewhere later in the code...
+//   SetThirdPartyMemoryFunctions(MyMemoryReporter::CountingAlloc,
+//                                MyMemoryReporter::CountingFree);
+template<typename T>
+class CountingAllocatorBase
+{
+public:
+  CountingAllocatorBase()
+  {
+#ifdef DEBUG
+    // There must be only one instance of this class, due to |sAmount| being
+    // static.
+    static bool hasRun = false;
+    MOZ_ASSERT(!hasRun);
+    hasRun = true;
+#endif
+  }
+
+  static size_t
+  MemoryAllocated()
+  {
+    return sAmount;
+  }
+
+  static void*
+  CountingMalloc(size_t size)
+  {
+    void* p = malloc(size);
+    sAmount += MallocSizeOfOnAlloc(p);
+    return p;
+  }
+
+  static void*
+  CountingCalloc(size_t nmemb, size_t size)
+  {
+    void* p = calloc(nmemb, size);
+    sAmount += MallocSizeOfOnAlloc(p);
+    return p;
+  }
+
+  static void*
+  CountingRealloc(void* p, size_t size)
+  {
+    size_t oldsize = MallocSizeOfOnFree(p);
+    void *pnew = realloc(p, size);
+    if (pnew) {
+      size_t newsize = MallocSizeOfOnAlloc(pnew);
+      sAmount += newsize - oldsize;
+    } else if (size == 0) {
+      // We asked for a 0-sized (re)allocation of some existing pointer
+      // and received NULL in return.  0-sized allocations are permitted
+      // to either return NULL or to allocate a unique object per call (!).
+      // For a malloc implementation that chooses the second strategy,
+      // that allocation may fail (unlikely, but possible).
+      //
+      // Given a NULL return value and an allocation size of 0, then, we
+      // don't know if that means the original pointer was freed or if
+      // the allocation of the unique object failed.  If the original
+      // pointer was freed, then we have nothing to do here.  If the
+      // allocation of the unique object failed, the original pointer is
+      // still valid and we ought to undo the decrement from above.
+      // However, we have no way of knowing how the underlying realloc
+      // implementation is behaving.  Assuming that the original pointer
+      // was freed is the safest course of action.  We do, however, need
+      // to note that we freed memory.
+      sAmount -= oldsize;
+    } else {
+      // realloc failed.  The amount allocated hasn't changed.
+    }
+    return pnew;
+  }
+
+  // Some library code expects that realloc(x, 0) will free x, which is not
+  // the behavior of the version of jemalloc we're using, so this wrapped
+  // version of realloc is needed.
+  static void*
+  CountingFreeingRealloc(void* p, size_t size)
+  {
+    if (size == 0) {
+      CountingFree(p);
+      return nullptr;
+    }
+    return CountingRealloc(p, size);
+  }
+
+  static void
+  CountingFree(void* p)
+  {
+    sAmount -= MallocSizeOfOnFree(p);
+    free(p);
+  }
+
+private:
+  // |sAmount| can be (implicitly) accessed by multiple threads, so it
+  // must be thread-safe.
+  static Atomic<size_t> sAmount;
+
+  MOZ_DEFINE_MALLOC_SIZE_OF_ON_ALLOC(MallocSizeOfOnAlloc)
+  MOZ_DEFINE_MALLOC_SIZE_OF_ON_FREE(MallocSizeOfOnFree)
+};
+
+} // namespace mozilla
+
+#endif // CountingAllocatorBase_h
diff --git a/xpcom/base/CycleCollectedJSContext.cpp b/xpcom/base/CycleCollectedJSContext.cpp
new file mode 100644
index 000000000..87e123078
--- /dev/null
+++ b/xpcom/base/CycleCollectedJSContext.cpp
@@ -0,0 +1,1717 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// We're dividing JS objects into 3 categories:
+//
+// 1. "real" roots, held by the JS engine itself or rooted through the root
+//    and lock JS APIs. Roots from this category are considered black in the
+//    cycle collector, any cycle they participate in is uncollectable.
+//
+// 2. certain roots held by C++ objects that are guaranteed to be alive.
+//    Roots from this category are considered black in the cycle collector,
+//    and any cycle they participate in is uncollectable. These roots are
+//    traced from TraceNativeBlackRoots.
+//
+// 3. all other roots held by C++ objects that participate in cycle
+//    collection, held by us (see TraceNativeGrayRoots). Roots from this
+//    category are considered grey in the cycle collector; whether or not
+//    they are collected depends on the objects that hold them.
+//
+// Note that if a root is in multiple categories the fact that it is in
+// category 1 or 2 that takes precedence, so it will be considered black.
+//
+// During garbage collection we switch to an additional mark color (gray)
+// when tracing inside TraceNativeGrayRoots. This allows us to walk those
+// roots later on and add all objects reachable only from them to the
+// cycle collector.
+//
+// Phases:
+//
+// 1. marking of the roots in category 1 by having the JS GC do its marking
+// 2. marking of the roots in category 2 by having the JS GC call us back
+//    (via JS_SetExtraGCRootsTracer) and running TraceNativeBlackRoots
+// 3. marking of the roots in category 3 by TraceNativeGrayRoots using an
+//    additional color (gray).
+// 4. end of GC, GC can sweep its heap
+//
+// At some later point, when the cycle collector runs:
+//
+// 5. walk gray objects and add them to the cycle collector, cycle collect
+//
+// JS objects that are part of cycles the cycle collector breaks will be
+// collected by the next JS GC.
+//
+// If WantAllTraces() is false the cycle collector will not traverse roots
+// from category 1 or any JS objects held by them. Any JS objects they hold
+// will already be marked by the JS GC and will thus be colored black
+// themselves. Any C++ objects they hold will have a missing (untraversed)
+// edge from the JS object to the C++ object and so it will be marked black
+// too. This decreases the number of objects that the cycle collector has to
+// deal with.
+// To improve debugging, if WantAllTraces() is true all JS objects are
+// traversed.
+
+#include "mozilla/CycleCollectedJSContext.h"
+#include <algorithm>
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/AutoRestore.h"
+#include "mozilla/Move.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Sprintf.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/TimelineConsumers.h"
+#include "mozilla/TimelineMarker.h"
+#include "mozilla/Unused.h"
+#include "mozilla/DebuggerOnGCRunnable.h"
+#include "mozilla/dom/DOMJSClass.h"
+#include "mozilla/dom/ProfileTimelineMarkerBinding.h"
+#include "mozilla/dom/Promise.h"
+#include "mozilla/dom/PromiseBinding.h"
+#include "mozilla/dom/PromiseDebugging.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "jsprf.h"
+#include "js/Debug.h"
+#include "nsContentUtils.h"
+#include "nsCycleCollectionNoteRootCallback.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsCycleCollector.h"
+#include "nsDOMJSUtils.h"
+#include "nsJSUtils.h"
+#include "nsWrapperCache.h"
+
+#ifdef MOZ_CRASHREPORTER
+#include "nsExceptionHandler.h"
+#endif
+
+#include "nsIException.h"
+#include "nsIPlatformInfo.h"
+#include "nsThread.h"
+#include "nsThreadUtils.h"
+#include "xpcpublic.h"
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+namespace mozilla {
+
+struct DeferredFinalizeFunctionHolder
+{
+  DeferredFinalizeFunction run;
+  void* data;
+};
+
+class IncrementalFinalizeRunnable : public Runnable
+{
+  typedef AutoTArray<DeferredFinalizeFunctionHolder, 16> DeferredFinalizeArray;
+  typedef CycleCollectedJSContext::DeferredFinalizerTable DeferredFinalizerTable;
+
+  CycleCollectedJSContext* mContext;
+  DeferredFinalizeArray mDeferredFinalizeFunctions;
+  uint32_t mFinalizeFunctionToRun;
+  bool mReleasing;
+
+  static const PRTime SliceMillis = 5; /* ms */
+
+public:
+  IncrementalFinalizeRunnable(CycleCollectedJSContext* aCx,
+                              DeferredFinalizerTable& aFinalizerTable);
+  virtual ~IncrementalFinalizeRunnable();
+
+  void ReleaseNow(bool aLimited);
+
+  NS_DECL_NSIRUNNABLE
+};
+
+} // namespace mozilla
+
+struct NoteWeakMapChildrenTracer : public JS::CallbackTracer
+{
+  NoteWeakMapChildrenTracer(JSContext* aCx,
+                            nsCycleCollectionNoteRootCallback& aCb)
+    : JS::CallbackTracer(aCx), mCb(aCb), mTracedAny(false), mMap(nullptr),
+      mKey(nullptr), mKeyDelegate(nullptr)
+  {
+  }
+  void onChild(const JS::GCCellPtr& aThing) override;
+  nsCycleCollectionNoteRootCallback& mCb;
+  bool mTracedAny;
+  JSObject* mMap;
+  JS::GCCellPtr mKey;
+  JSObject* mKeyDelegate;
+};
+
+void
+NoteWeakMapChildrenTracer::onChild(const JS::GCCellPtr& aThing)
+{
+  if (aThing.is<JSString>()) {
+    return;
+  }
+
+  if (!JS::GCThingIsMarkedGray(aThing) && !mCb.WantAllTraces()) {
+    return;
+  }
+
+  if (AddToCCKind(aThing.kind())) {
+    mCb.NoteWeakMapping(mMap, mKey, mKeyDelegate, aThing);
+    mTracedAny = true;
+  } else {
+    JS::TraceChildren(this, aThing);
+  }
+}
+
+struct NoteWeakMapsTracer : public js::WeakMapTracer
+{
+  NoteWeakMapsTracer(JSContext* aCx, nsCycleCollectionNoteRootCallback& aCccb)
+    : js::WeakMapTracer(aCx), mCb(aCccb), mChildTracer(aCx, aCccb)
+  {
+  }
+  void trace(JSObject* aMap, JS::GCCellPtr aKey, JS::GCCellPtr aValue) override;
+  nsCycleCollectionNoteRootCallback& mCb;
+  NoteWeakMapChildrenTracer mChildTracer;
+};
+
+void
+NoteWeakMapsTracer::trace(JSObject* aMap, JS::GCCellPtr aKey,
+                          JS::GCCellPtr aValue)
+{
+  // If nothing that could be held alive by this entry is marked gray, return.
+  if ((!aKey || !JS::GCThingIsMarkedGray(aKey)) &&
+      MOZ_LIKELY(!mCb.WantAllTraces())) {
+    if (!aValue || !JS::GCThingIsMarkedGray(aValue) || aValue.is<JSString>()) {
+      return;
+    }
+  }
+
+  // The cycle collector can only properly reason about weak maps if it can
+  // reason about the liveness of their keys, which in turn requires that
+  // the key can be represented in the cycle collector graph.  All existing
+  // uses of weak maps use either objects or scripts as keys, which are okay.
+  MOZ_ASSERT(AddToCCKind(aKey.kind()));
+
+  // As an emergency fallback for non-debug builds, if the key is not
+  // representable in the cycle collector graph, we treat it as marked.  This
+  // can cause leaks, but is preferable to ignoring the binding, which could
+  // cause the cycle collector to free live objects.
+  if (!AddToCCKind(aKey.kind())) {
+    aKey = nullptr;
+  }
+
+  JSObject* kdelegate = nullptr;
+  if (aKey.is<JSObject>()) {
+    kdelegate = js::GetWeakmapKeyDelegate(&aKey.as<JSObject>());
+  }
+
+  if (AddToCCKind(aValue.kind())) {
+    mCb.NoteWeakMapping(aMap, aKey, kdelegate, aValue);
+  } else {
+    mChildTracer.mTracedAny = false;
+    mChildTracer.mMap = aMap;
+    mChildTracer.mKey = aKey;
+    mChildTracer.mKeyDelegate = kdelegate;
+
+    if (!aValue.is<JSString>()) {
+      JS::TraceChildren(&mChildTracer, aValue);
+    }
+
+    // The delegate could hold alive the key, so report something to the CC
+    // if we haven't already.
+    if (!mChildTracer.mTracedAny &&
+        aKey && JS::GCThingIsMarkedGray(aKey) && kdelegate) {
+      mCb.NoteWeakMapping(aMap, aKey, kdelegate, nullptr);
+    }
+  }
+}
+
+// This is based on the logic in FixWeakMappingGrayBitsTracer::trace.
+struct FixWeakMappingGrayBitsTracer : public js::WeakMapTracer
+{
+  explicit FixWeakMappingGrayBitsTracer(JSContext* aCx)
+    : js::WeakMapTracer(aCx)
+  {
+  }
+
+  void
+  FixAll()
+  {
+    do {
+      mAnyMarked = false;
+      js::TraceWeakMaps(this);
+    } while (mAnyMarked);
+  }
+
+  void trace(JSObject* aMap, JS::GCCellPtr aKey, JS::GCCellPtr aValue) override
+  {
+    // If nothing that could be held alive by this entry is marked gray, return.
+    bool keyMightNeedMarking = aKey && JS::GCThingIsMarkedGray(aKey);
+    bool valueMightNeedMarking = aValue && JS::GCThingIsMarkedGray(aValue) &&
+                                 aValue.kind() != JS::TraceKind::String;
+    if (!keyMightNeedMarking && !valueMightNeedMarking) {
+      return;
+    }
+
+    if (!AddToCCKind(aKey.kind())) {
+      aKey = nullptr;
+    }
+
+    if (keyMightNeedMarking && aKey.is<JSObject>()) {
+      JSObject* kdelegate = js::GetWeakmapKeyDelegate(&aKey.as<JSObject>());
+      if (kdelegate && !JS::ObjectIsMarkedGray(kdelegate) &&
+          (!aMap || !JS::ObjectIsMarkedGray(aMap)))
+      {
+        if (JS::UnmarkGrayGCThingRecursively(aKey)) {
+          mAnyMarked = true;
+        }
+      }
+    }
+
+    if (aValue && JS::GCThingIsMarkedGray(aValue) &&
+        (!aKey || !JS::GCThingIsMarkedGray(aKey)) &&
+        (!aMap || !JS::ObjectIsMarkedGray(aMap)) &&
+        aValue.kind() != JS::TraceKind::Shape) {
+      if (JS::UnmarkGrayGCThingRecursively(aValue)) {
+        mAnyMarked = true;
+      }
+    }
+  }
+
+  MOZ_INIT_OUTSIDE_CTOR bool mAnyMarked;
+};
+
+static void
+CheckParticipatesInCycleCollection(JS::GCCellPtr aThing, const char* aName,
+                                   void* aClosure)
+{
+  bool* cycleCollectionEnabled = static_cast<bool*>(aClosure);
+
+  if (*cycleCollectionEnabled) {
+    return;
+  }
+
+  if (AddToCCKind(aThing.kind()) && JS::GCThingIsMarkedGray(aThing)) {
+    *cycleCollectionEnabled = true;
+  }
+}
+
+NS_IMETHODIMP
+JSGCThingParticipant::Traverse(void* aPtr,
+                               nsCycleCollectionTraversalCallback& aCb)
+{
+  auto runtime = reinterpret_cast<CycleCollectedJSContext*>(
+    reinterpret_cast<char*>(this) - offsetof(CycleCollectedJSContext,
+                                             mGCThingCycleCollectorGlobal));
+
+  JS::GCCellPtr cellPtr(aPtr, JS::GCThingTraceKind(aPtr));
+  runtime->TraverseGCThing(CycleCollectedJSContext::TRAVERSE_FULL, cellPtr, aCb);
+  return NS_OK;
+}
+
+// NB: This is only used to initialize the participant in
+// CycleCollectedJSContext. It should never be used directly.
+static JSGCThingParticipant sGCThingCycleCollectorGlobal;
+
+NS_IMETHODIMP
+JSZoneParticipant::Traverse(void* aPtr, nsCycleCollectionTraversalCallback& aCb)
+{
+  auto runtime = reinterpret_cast<CycleCollectedJSContext*>(
+    reinterpret_cast<char*>(this) - offsetof(CycleCollectedJSContext,
+                                             mJSZoneCycleCollectorGlobal));
+
+  MOZ_ASSERT(!aCb.WantAllTraces());
+  JS::Zone* zone = static_cast<JS::Zone*>(aPtr);
+
+  runtime->TraverseZone(zone, aCb);
+  return NS_OK;
+}
+
+struct TraversalTracer : public JS::CallbackTracer
+{
+  TraversalTracer(JSContext* aCx, nsCycleCollectionTraversalCallback& aCb)
+    : JS::CallbackTracer(aCx, DoNotTraceWeakMaps), mCb(aCb)
+  {
+  }
+  void onChild(const JS::GCCellPtr& aThing) override;
+  nsCycleCollectionTraversalCallback& mCb;
+};
+
+void
+TraversalTracer::onChild(const JS::GCCellPtr& aThing)
+{
+  // Don't traverse non-gray objects, unless we want all traces.
+  if (!JS::GCThingIsMarkedGray(aThing) && !mCb.WantAllTraces()) {
+    return;
+  }
+
+  /*
+   * This function needs to be careful to avoid stack overflow. Normally, when
+   * AddToCCKind is true, the recursion terminates immediately as we just add
+   * |thing| to the CC graph. So overflow is only possible when there are long
+   * or cyclic chains of non-AddToCCKind GC things. Places where this can occur
+   * use special APIs to handle such chains iteratively.
+   */
+  if (AddToCCKind(aThing.kind())) {
+    if (MOZ_UNLIKELY(mCb.WantDebugInfo())) {
+      char buffer[200];
+      getTracingEdgeName(buffer, sizeof(buffer));
+      mCb.NoteNextEdgeName(buffer);
+    }
+    mCb.NoteJSChild(aThing);
+  } else if (aThing.is<js::Shape>()) {
+    // The maximum depth of traversal when tracing a Shape is unbounded, due to
+    // the parent pointers on the shape.
+    JS_TraceShapeCycleCollectorChildren(this, aThing);
+  } else if (aThing.is<js::ObjectGroup>()) {
+    // The maximum depth of traversal when tracing an ObjectGroup is unbounded,
+    // due to information attached to the groups which can lead other groups to
+    // be traced.
+    JS_TraceObjectGroupCycleCollectorChildren(this, aThing);
+  } else if (!aThing.is<JSString>()) {
+    JS::TraceChildren(this, aThing);
+  }
+}
+
+static void
+NoteJSChildGrayWrapperShim(void* aData, JS::GCCellPtr aThing)
+{
+  TraversalTracer* trc = static_cast<TraversalTracer*>(aData);
+  trc->onChild(aThing);
+}
+
+/*
+ * The cycle collection participant for a Zone is intended to produce the same
+ * results as if all of the gray GCthings in a zone were merged into a single node,
+ * except for self-edges. This avoids the overhead of representing all of the GCthings in
+ * the zone in the cycle collector graph, which should be much faster if many of
+ * the GCthings in the zone are gray.
+ *
+ * Zone merging should not always be used, because it is a conservative
+ * approximation of the true cycle collector graph that can incorrectly identify some
+ * garbage objects as being live. For instance, consider two cycles that pass through a
+ * zone, where one is garbage and the other is live. If we merge the entire
+ * zone, the cycle collector will think that both are alive.
+ *
+ * We don't have to worry about losing track of a garbage cycle, because any such garbage
+ * cycle incorrectly identified as live must contain at least one C++ to JS edge, and
+ * XPConnect will always add the C++ object to the CC graph. (This is in contrast to pure
+ * C++ garbage cycles, which must always be properly identified, because we clear the
+ * purple buffer during every CC, which may contain the last reference to a garbage
+ * cycle.)
+ */
+
+// NB: This is only used to initialize the participant in
+// CycleCollectedJSContext. It should never be used directly.
+static const JSZoneParticipant sJSZoneCycleCollectorGlobal;
+
+static
+void JSObjectsTenuredCb(JSContext* aContext, void* aData)
+{
+  static_cast<CycleCollectedJSContext*>(aData)->JSObjectsTenured();
+}
+
+bool
+mozilla::GetBuildId(JS::BuildIdCharVector* aBuildID)
+{
+  nsCOMPtr<nsIPlatformInfo> info = do_GetService("@mozilla.org/xre/app-info;1");
+  if (!info) {
+    return false;
+  }
+
+  nsCString buildID;
+  nsresult rv = info->GetPlatformBuildID(buildID);
+  NS_ENSURE_SUCCESS(rv, false);
+
+  if (!aBuildID->resize(buildID.Length())) {
+    return false;
+  }
+
+  for (size_t i = 0; i < buildID.Length(); i++) {
+    (*aBuildID)[i] = buildID[i];
+  }
+
+  return true;
+}
+
+CycleCollectedJSContext::CycleCollectedJSContext()
+  : mGCThingCycleCollectorGlobal(sGCThingCycleCollectorGlobal)
+  , mJSZoneCycleCollectorGlobal(sJSZoneCycleCollectorGlobal)
+  , mJSContext(nullptr)
+  , mPrevGCSliceCallback(nullptr)
+  , mPrevGCNurseryCollectionCallback(nullptr)
+  , mJSHolders(256)
+  , mDoingStableStates(false)
+  , mDisableMicroTaskCheckpoint(false)
+  , mOutOfMemoryState(OOMState::OK)
+  , mLargeAllocationFailureState(OOMState::OK)
+{
+  nsCOMPtr<nsIThread> thread = do_GetCurrentThread();
+  mOwningThread = thread.forget().downcast<nsThread>().take();
+  MOZ_RELEASE_ASSERT(mOwningThread);
+}
+
+CycleCollectedJSContext::~CycleCollectedJSContext()
+{
+  // If the allocation failed, here we are.
+  if (!mJSContext) {
+    return;
+  }
+
+  MOZ_ASSERT(!mDeferredFinalizerTable.Count());
+
+  // Last chance to process any events.
+  ProcessMetastableStateQueue(mBaseRecursionDepth);
+  MOZ_ASSERT(mMetastableStateEvents.IsEmpty());
+
+  ProcessStableStateQueue();
+  MOZ_ASSERT(mStableStateEvents.IsEmpty());
+
+  // Clear mPendingException first, since it might be cycle collected.
+  mPendingException = nullptr;
+
+  MOZ_ASSERT(mDebuggerPromiseMicroTaskQueue.empty());
+  MOZ_ASSERT(mPromiseMicroTaskQueue.empty());
+
+#ifdef SPIDERMONKEY_PROMISE
+  mUncaughtRejections.reset();
+  mConsumedRejections.reset();
+#endif // SPIDERMONKEY_PROMISE
+
+  JS_DestroyContext(mJSContext);
+  mJSContext = nullptr;
+  nsCycleCollector_forgetJSContext();
+
+  mozilla::dom::DestroyScriptSettings();
+
+  mOwningThread->SetScriptObserver(nullptr);
+  NS_RELEASE(mOwningThread);
+}
+
+static void
+MozCrashWarningReporter(JSContext*, JSErrorReport*)
+{
+  MOZ_CRASH("Why is someone touching JSAPI without an AutoJSAPI?");
+}
+
+nsresult
+CycleCollectedJSContext::Initialize(JSContext* aParentContext,
+                                    uint32_t aMaxBytes,
+                                    uint32_t aMaxNurseryBytes)
+{
+  MOZ_ASSERT(!mJSContext);
+
+  mOwningThread->SetScriptObserver(this);
+  // The main thread has a base recursion depth of 0, workers of 1.
+  mBaseRecursionDepth = RecursionDepth();
+
+  mozilla::dom::InitScriptSettings();
+  mJSContext = JS_NewContext(aMaxBytes, aMaxNurseryBytes, aParentContext);
+  if (!mJSContext) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  NS_GetCurrentThread()->SetCanInvokeJS(true);
+
+  if (!JS_AddExtraGCRootsTracer(mJSContext, TraceBlackJS, this)) {
+    MOZ_CRASH("JS_AddExtraGCRootsTracer failed");
+  }
+  JS_SetGrayGCRootsTracer(mJSContext, TraceGrayJS, this);
+  JS_SetGCCallback(mJSContext, GCCallback, this);
+  mPrevGCSliceCallback = JS::SetGCSliceCallback(mJSContext, GCSliceCallback);
+
+  if (NS_IsMainThread()) {
+    // We would like to support all threads here, but the way timeline consumers
+    // are set up currently, you can either add a marker for one specific
+    // docshell, or for every consumer globally. We would like to add a marker
+    // for every consumer observing anything on this thread, but that is not
+    // currently possible. For now, add global markers only when we are on the
+    // main thread, since the UI for this tracing data only displays data
+    // relevant to the main-thread.
+    mPrevGCNurseryCollectionCallback = JS::SetGCNurseryCollectionCallback(
+      mJSContext, GCNurseryCollectionCallback);
+  }
+
+  JS_SetObjectsTenuredCallback(mJSContext, JSObjectsTenuredCb, this);
+  JS::SetOutOfMemoryCallback(mJSContext, OutOfMemoryCallback, this);
+  JS::SetLargeAllocationFailureCallback(mJSContext,
+                                        LargeAllocationFailureCallback, this);
+  JS_SetDestroyZoneCallback(mJSContext, XPCStringConvert::FreeZoneCache);
+  JS_SetSweepZoneCallback(mJSContext, XPCStringConvert::ClearZoneCache);
+  JS::SetBuildIdOp(mJSContext, GetBuildId);
+  JS::SetWarningReporter(mJSContext, MozCrashWarningReporter);
+#ifdef MOZ_CRASHREPORTER
+    js::AutoEnterOOMUnsafeRegion::setAnnotateOOMAllocationSizeCallback(
+            CrashReporter::AnnotateOOMAllocationSize);
+#endif
+
+  static js::DOMCallbacks DOMcallbacks = {
+    InstanceClassHasProtoAtDepth
+  };
+  SetDOMCallbacks(mJSContext, &DOMcallbacks);
+  js::SetScriptEnvironmentPreparer(mJSContext, &mEnvironmentPreparer);
+
+  JS::SetGetIncumbentGlobalCallback(mJSContext, GetIncumbentGlobalCallback);
+
+#ifdef SPIDERMONKEY_PROMISE
+  JS::SetEnqueuePromiseJobCallback(mJSContext, EnqueuePromiseJobCallback, this);
+  JS::SetPromiseRejectionTrackerCallback(mJSContext, PromiseRejectionTrackerCallback, this);
+  mUncaughtRejections.init(mJSContext, JS::GCVector<JSObject*, 0, js::SystemAllocPolicy>(js::SystemAllocPolicy()));
+  mConsumedRejections.init(mJSContext, JS::GCVector<JSObject*, 0, js::SystemAllocPolicy>(js::SystemAllocPolicy()));
+#endif // SPIDERMONKEY_PROMISE
+
+  JS::dbg::SetDebuggerMallocSizeOf(mJSContext, moz_malloc_size_of);
+
+  nsCycleCollector_registerJSContext(this);
+
+  return NS_OK;
+}
+
+size_t
+CycleCollectedJSContext::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
+{
+  size_t n = 0;
+
+  // We're deliberately not measuring anything hanging off the entries in
+  // mJSHolders.
+  n += mJSHolders.ShallowSizeOfExcludingThis(aMallocSizeOf);
+
+  return n;
+}
+
+void
+CycleCollectedJSContext::UnmarkSkippableJSHolders()
+{
+  for (auto iter = mJSHolders.Iter(); !iter.Done(); iter.Next()) {
+    void* holder = iter.Key();
+    nsScriptObjectTracer*& tracer = iter.Data();
+    tracer->CanSkip(holder, true);
+  }
+}
+
+void
+CycleCollectedJSContext::DescribeGCThing(bool aIsMarked, JS::GCCellPtr aThing,
+                                         nsCycleCollectionTraversalCallback& aCb) const
+{
+  if (!aCb.WantDebugInfo()) {
+    aCb.DescribeGCedNode(aIsMarked, "JS Object");
+    return;
+  }
+
+  char name[72];
+  uint64_t compartmentAddress = 0;
+  if (aThing.is<JSObject>()) {
+    JSObject* obj = &aThing.as<JSObject>();
+    compartmentAddress = (uint64_t)js::GetObjectCompartment(obj);
+    const js::Class* clasp = js::GetObjectClass(obj);
+
+    // Give the subclass a chance to do something
+    if (DescribeCustomObjects(obj, clasp, name)) {
+      // Nothing else to do!
+    } else if (js::IsFunctionObject(obj)) {
+      JSFunction* fun = JS_GetObjectFunction(obj);
+      JSString* str = JS_GetFunctionDisplayId(fun);
+      if (str) {
+        JSFlatString* flat = JS_ASSERT_STRING_IS_FLAT(str);
+        nsAutoString chars;
+        AssignJSFlatString(chars, flat);
+        NS_ConvertUTF16toUTF8 fname(chars);
+        SprintfLiteral(name, "JS Object (Function - %s)", fname.get());
+      } else {
+        SprintfLiteral(name, "JS Object (Function)");
+      }
+    } else {
+      SprintfLiteral(name, "JS Object (%s)", clasp->name);
+    }
+  } else {
+    SprintfLiteral(name, "JS %s", JS::GCTraceKindToAscii(aThing.kind()));
+  }
+
+  // Disable printing global for objects while we figure out ObjShrink fallout.
+  aCb.DescribeGCedNode(aIsMarked, name, compartmentAddress);
+}
+
+void
+CycleCollectedJSContext::NoteGCThingJSChildren(JS::GCCellPtr aThing,
+                                               nsCycleCollectionTraversalCallback& aCb) const
+{
+  MOZ_ASSERT(mJSContext);
+  TraversalTracer trc(mJSContext, aCb);
+  JS::TraceChildren(&trc, aThing);
+}
+
+void
+CycleCollectedJSContext::NoteGCThingXPCOMChildren(const js::Class* aClasp,
+                                                  JSObject* aObj,
+                                                  nsCycleCollectionTraversalCallback& aCb) const
+{
+  MOZ_ASSERT(aClasp);
+  MOZ_ASSERT(aClasp == js::GetObjectClass(aObj));
+
+  if (NoteCustomGCThingXPCOMChildren(aClasp, aObj, aCb)) {
+    // Nothing else to do!
+    return;
+  }
+  // XXX This test does seem fragile, we should probably whitelist classes
+  //     that do hold a strong reference, but that might not be possible.
+  else if (aClasp->flags & JSCLASS_HAS_PRIVATE &&
+           aClasp->flags & JSCLASS_PRIVATE_IS_NSISUPPORTS) {
+    NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(aCb, "js::GetObjectPrivate(obj)");
+    aCb.NoteXPCOMChild(static_cast<nsISupports*>(js::GetObjectPrivate(aObj)));
+  } else {
+    const DOMJSClass* domClass = GetDOMClass(aObj);
+    if (domClass) {
+      NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(aCb, "UnwrapDOMObject(obj)");
+      // It's possible that our object is an unforgeable holder object, in
+      // which case it doesn't actually have a C++ DOM object associated with
+      // it.  Use UnwrapPossiblyNotInitializedDOMObject, which produces null in
+      // that case, since NoteXPCOMChild/NoteNativeChild are null-safe.
+      if (domClass->mDOMObjectIsISupports) {
+        aCb.NoteXPCOMChild(UnwrapPossiblyNotInitializedDOMObject<nsISupports>(aObj));
+      } else if (domClass->mParticipant) {
+        aCb.NoteNativeChild(UnwrapPossiblyNotInitializedDOMObject<void>(aObj),
+                            domClass->mParticipant);
+      }
+    }
+  }
+}
+
+void
+CycleCollectedJSContext::TraverseGCThing(TraverseSelect aTs, JS::GCCellPtr aThing,
+                                         nsCycleCollectionTraversalCallback& aCb)
+{
+  bool isMarkedGray = JS::GCThingIsMarkedGray(aThing);
+
+  if (aTs == TRAVERSE_FULL) {
+    DescribeGCThing(!isMarkedGray, aThing, aCb);
+  }
+
+  // If this object is alive, then all of its children are alive. For JS objects,
+  // the black-gray invariant ensures the children are also marked black. For C++
+  // objects, the ref count from this object will keep them alive. Thus we don't
+  // need to trace our children, unless we are debugging using WantAllTraces.
+  if (!isMarkedGray && !aCb.WantAllTraces()) {
+    return;
+  }
+
+  if (aTs == TRAVERSE_FULL) {
+    NoteGCThingJSChildren(aThing, aCb);
+  }
+
+  if (aThing.is<JSObject>()) {
+    JSObject* obj = &aThing.as<JSObject>();
+    NoteGCThingXPCOMChildren(js::GetObjectClass(obj), obj, aCb);
+  }
+}
+
+struct TraverseObjectShimClosure
+{
+  nsCycleCollectionTraversalCallback& cb;
+  CycleCollectedJSContext* self;
+};
+
+void
+CycleCollectedJSContext::TraverseZone(JS::Zone* aZone,
+                                      nsCycleCollectionTraversalCallback& aCb)
+{
+  MOZ_ASSERT(mJSContext);
+
+  /*
+   * We treat the zone as being gray. We handle non-gray GCthings in the
+   * zone by not reporting their children to the CC. The black-gray invariant
+   * ensures that any JS children will also be non-gray, and thus don't need to be
+   * added to the graph. For C++ children, not representing the edge from the
+   * non-gray JS GCthings to the C++ object will keep the child alive.
+   *
+   * We don't allow zone merging in a WantAllTraces CC, because then these
+   * assumptions don't hold.
+   */
+  aCb.DescribeGCedNode(false, "JS Zone");
+
+  /*
+   * Every JS child of everything in the zone is either in the zone
+   * or is a cross-compartment wrapper. In the former case, we don't need to
+   * represent these edges in the CC graph because JS objects are not ref counted.
+   * In the latter case, the JS engine keeps a map of these wrappers, which we
+   * iterate over. Edges between compartments in the same zone will add
+   * unnecessary loop edges to the graph (bug 842137).
+   */
+  TraversalTracer trc(mJSContext, aCb);
+  js::VisitGrayWrapperTargets(aZone, NoteJSChildGrayWrapperShim, &trc);
+
+  /*
+   * To find C++ children of things in the zone, we scan every JS Object in
+   * the zone. Only JS Objects can have C++ children.
+   */
+  TraverseObjectShimClosure closure = { aCb, this };
+  js::IterateGrayObjects(aZone, TraverseObjectShim, &closure);
+}
+
+/* static */ void
+CycleCollectedJSContext::TraverseObjectShim(void* aData, JS::GCCellPtr aThing)
+{
+  TraverseObjectShimClosure* closure =
+    static_cast<TraverseObjectShimClosure*>(aData);
+
+  MOZ_ASSERT(aThing.is<JSObject>());
+  closure->self->TraverseGCThing(CycleCollectedJSContext::TRAVERSE_CPP,
+                                 aThing, closure->cb);
+}
+
+void
+CycleCollectedJSContext::TraverseNativeRoots(nsCycleCollectionNoteRootCallback& aCb)
+{
+  // NB: This is here just to preserve the existing XPConnect order. I doubt it
+  // would hurt to do this after the JS holders.
+  TraverseAdditionalNativeRoots(aCb);
+
+  for (auto iter = mJSHolders.Iter(); !iter.Done(); iter.Next()) {
+    void* holder = iter.Key();
+    nsScriptObjectTracer*& tracer = iter.Data();
+
+    bool noteRoot = false;
+    if (MOZ_UNLIKELY(aCb.WantAllTraces())) {
+      noteRoot = true;
+    } else {
+      tracer->Trace(holder,
+                    TraceCallbackFunc(CheckParticipatesInCycleCollection),
+                    &noteRoot);
+    }
+
+    if (noteRoot) {
+      aCb.NoteNativeRoot(holder, tracer);
+    }
+  }
+}
+
+/* static */ void
+CycleCollectedJSContext::TraceBlackJS(JSTracer* aTracer, void* aData)
+{
+  CycleCollectedJSContext* self = static_cast<CycleCollectedJSContext*>(aData);
+
+  self->TraceNativeBlackRoots(aTracer);
+}
+
+/* static */ void
+CycleCollectedJSContext::TraceGrayJS(JSTracer* aTracer, void* aData)
+{
+  CycleCollectedJSContext* self = static_cast<CycleCollectedJSContext*>(aData);
+
+  // Mark these roots as gray so the CC can walk them later.
+  self->TraceNativeGrayRoots(aTracer);
+}
+
+/* static */ void
+CycleCollectedJSContext::GCCallback(JSContext* aContext,
+                                    JSGCStatus aStatus,
+                                    void* aData)
+{
+  CycleCollectedJSContext* self = static_cast<CycleCollectedJSContext*>(aData);
+
+  MOZ_ASSERT(aContext == self->Context());
+
+  self->OnGC(aStatus);
+}
+
+/* static */ void
+CycleCollectedJSContext::GCSliceCallback(JSContext* aContext,
+                                         JS::GCProgress aProgress,
+                                         const JS::GCDescription& aDesc)
+{
+  CycleCollectedJSContext* self = CycleCollectedJSContext::Get();
+  MOZ_ASSERT(self->Context() == aContext);
+
+  if (aProgress == JS::GC_CYCLE_END) {
+    JS::gcreason::Reason reason = aDesc.reason_;
+    Unused <<
+      NS_WARN_IF(NS_FAILED(DebuggerOnGCRunnable::Enqueue(aContext, aDesc)) &&
+                 reason != JS::gcreason::SHUTDOWN_CC &&
+                 reason != JS::gcreason::DESTROY_RUNTIME &&
+                 reason != JS::gcreason::XPCONNECT_SHUTDOWN);
+  }
+
+  if (self->mPrevGCSliceCallback) {
+    self->mPrevGCSliceCallback(aContext, aProgress, aDesc);
+  }
+}
+
+class MinorGCMarker : public TimelineMarker
+{
+private:
+  JS::gcreason::Reason mReason;
+
+public:
+  MinorGCMarker(MarkerTracingType aTracingType,
+                JS::gcreason::Reason aReason)
+    : TimelineMarker("MinorGC",
+                     aTracingType,
+                     MarkerStackRequest::NO_STACK)
+    , mReason(aReason)
+    {
+      MOZ_ASSERT(aTracingType == MarkerTracingType::START ||
+                 aTracingType == MarkerTracingType::END);
+    }
+
+  MinorGCMarker(JS::GCNurseryProgress aProgress,
+                JS::gcreason::Reason aReason)
+    : TimelineMarker("MinorGC",
+                     aProgress == JS::GCNurseryProgress::GC_NURSERY_COLLECTION_START
+                       ? MarkerTracingType::START
+                       : MarkerTracingType::END,
+                     MarkerStackRequest::NO_STACK)
+    , mReason(aReason)
+  { }
+
+  virtual void
+  AddDetails(JSContext* aCx,
+             dom::ProfileTimelineMarker& aMarker) override
+  {
+    TimelineMarker::AddDetails(aCx, aMarker);
+
+    if (GetTracingType() == MarkerTracingType::START) {
+      auto reason = JS::gcreason::ExplainReason(mReason);
+      aMarker.mCauseName.Construct(NS_ConvertUTF8toUTF16(reason));
+    }
+  }
+
+  virtual UniquePtr<AbstractTimelineMarker>
+  Clone() override
+  {
+    auto clone = MakeUnique<MinorGCMarker>(GetTracingType(), mReason);
+    clone->SetCustomTime(GetTime());
+    return UniquePtr<AbstractTimelineMarker>(Move(clone));
+  }
+};
+
+/* static */ void
+CycleCollectedJSContext::GCNurseryCollectionCallback(JSContext* aContext,
+                                                     JS::GCNurseryProgress aProgress,
+                                                     JS::gcreason::Reason aReason)
+{
+  CycleCollectedJSContext* self = CycleCollectedJSContext::Get();
+  MOZ_ASSERT(self->Context() == aContext);
+  MOZ_ASSERT(NS_IsMainThread());
+
+  RefPtr<TimelineConsumers> timelines = TimelineConsumers::Get();
+  if (timelines && !timelines->IsEmpty()) {
+    UniquePtr<AbstractTimelineMarker> abstractMarker(
+      MakeUnique<MinorGCMarker>(aProgress, aReason));
+    timelines->AddMarkerForAllObservedDocShells(abstractMarker);
+  }
+
+  if (self->mPrevGCNurseryCollectionCallback) {
+    self->mPrevGCNurseryCollectionCallback(aContext, aProgress, aReason);
+  }
+}
+
+
+/* static */ void
+CycleCollectedJSContext::OutOfMemoryCallback(JSContext* aContext,
+                                             void* aData)
+{
+  CycleCollectedJSContext* self = static_cast<CycleCollectedJSContext*>(aData);
+
+  MOZ_ASSERT(aContext == self->Context());
+
+  self->OnOutOfMemory();
+}
+
+/* static */ void
+CycleCollectedJSContext::LargeAllocationFailureCallback(void* aData)
+{
+  CycleCollectedJSContext* self = static_cast<CycleCollectedJSContext*>(aData);
+
+  self->OnLargeAllocationFailure();
+}
+
+class PromiseJobRunnable final : public Runnable
+{
+public:
+  PromiseJobRunnable(JS::HandleObject aCallback, JS::HandleObject aAllocationSite,
+                     nsIGlobalObject* aIncumbentGlobal)
+    : mCallback(new PromiseJobCallback(aCallback, aAllocationSite, aIncumbentGlobal))
+  {
+  }
+
+  virtual ~PromiseJobRunnable()
+  {
+  }
+
+protected:
+  NS_IMETHOD
+  Run() override
+  {
+    nsIGlobalObject* global = xpc::NativeGlobal(mCallback->CallbackPreserveColor());
+    if (global && !global->IsDying()) {
+      mCallback->Call("promise callback");
+    }
+    return NS_OK;
+  }
+
+private:
+  RefPtr<PromiseJobCallback> mCallback;
+};
+
+/* static */
+JSObject*
+CycleCollectedJSContext::GetIncumbentGlobalCallback(JSContext* aCx)
+{
+  nsIGlobalObject* global = mozilla::dom::GetIncumbentGlobal();
+  if (global) {
+    return global->GetGlobalJSObject();
+  }
+  return nullptr;
+}
+
+/* static */
+bool
+CycleCollectedJSContext::EnqueuePromiseJobCallback(JSContext* aCx,
+                                                   JS::HandleObject aJob,
+                                                   JS::HandleObject aAllocationSite,
+                                                   JS::HandleObject aIncumbentGlobal,
+                                                   void* aData)
+{
+  CycleCollectedJSContext* self = static_cast<CycleCollectedJSContext*>(aData);
+  MOZ_ASSERT(aCx == self->Context());
+  MOZ_ASSERT(Get() == self);
+
+  nsIGlobalObject* global = nullptr;
+  if (aIncumbentGlobal) {
+    global = xpc::NativeGlobal(aIncumbentGlobal);
+  }
+  nsCOMPtr<nsIRunnable> runnable = new PromiseJobRunnable(aJob, aAllocationSite, global);
+  self->DispatchToMicroTask(runnable.forget());
+  return true;
+}
+
+#ifdef SPIDERMONKEY_PROMISE
+/* static */
+void
+CycleCollectedJSContext::PromiseRejectionTrackerCallback(JSContext* aCx,
+                                                         JS::HandleObject aPromise,
+                                                         PromiseRejectionHandlingState state,
+                                                         void* aData)
+{
+#ifdef DEBUG
+  CycleCollectedJSContext* self = static_cast<CycleCollectedJSContext*>(aData);
+#endif // DEBUG
+  MOZ_ASSERT(aCx == self->Context());
+  MOZ_ASSERT(Get() == self);
+
+  if (state == PromiseRejectionHandlingState::Unhandled) {
+    PromiseDebugging::AddUncaughtRejection(aPromise);
+  } else {
+    PromiseDebugging::AddConsumedRejection(aPromise);
+  }
+}
+#endif // SPIDERMONKEY_PROMISE
+
+struct JsGcTracer : public TraceCallbacks
+{
+  virtual void Trace(JS::Heap<JS::Value>* aPtr, const char* aName,
+                     void* aClosure) const override
+  {
+    JS::TraceEdge(static_cast<JSTracer*>(aClosure), aPtr, aName);
+  }
+  virtual void Trace(JS::Heap<jsid>* aPtr, const char* aName,
+                     void* aClosure) const override
+  {
+    JS::TraceEdge(static_cast<JSTracer*>(aClosure), aPtr, aName);
+  }
+  virtual void Trace(JS::Heap<JSObject*>* aPtr, const char* aName,
+                     void* aClosure) const override
+  {
+    JS::TraceEdge(static_cast<JSTracer*>(aClosure), aPtr, aName);
+  }
+  virtual void Trace(JSObject** aPtr, const char* aName,
+                     void* aClosure) const override
+  {
+    js::UnsafeTraceManuallyBarrieredEdge(static_cast<JSTracer*>(aClosure), aPtr, aName);
+  }
+  virtual void Trace(JS::TenuredHeap<JSObject*>* aPtr, const char* aName,
+                     void* aClosure) const override
+  {
+    JS::TraceEdge(static_cast<JSTracer*>(aClosure), aPtr, aName);
+  }
+  virtual void Trace(JS::Heap<JSString*>* aPtr, const char* aName,
+                     void* aClosure) const override
+  {
+    JS::TraceEdge(static_cast<JSTracer*>(aClosure), aPtr, aName);
+  }
+  virtual void Trace(JS::Heap<JSScript*>* aPtr, const char* aName,
+                     void* aClosure) const override
+  {
+    JS::TraceEdge(static_cast<JSTracer*>(aClosure), aPtr, aName);
+  }
+  virtual void Trace(JS::Heap<JSFunction*>* aPtr, const char* aName,
+                     void* aClosure) const override
+  {
+    JS::TraceEdge(static_cast<JSTracer*>(aClosure), aPtr, aName);
+  }
+};
+
+void
+mozilla::TraceScriptHolder(nsISupports* aHolder, JSTracer* aTracer)
+{
+  nsXPCOMCycleCollectionParticipant* participant = nullptr;
+  CallQueryInterface(aHolder, &participant);
+  participant->Trace(aHolder, JsGcTracer(), aTracer);
+}
+
+void
+CycleCollectedJSContext::TraceNativeGrayRoots(JSTracer* aTracer)
+{
+  MOZ_ASSERT(mJSContext);
+
+  // NB: This is here just to preserve the existing XPConnect order. I doubt it
+  // would hurt to do this after the JS holders.
+  TraceAdditionalNativeGrayRoots(aTracer);
+
+  for (auto iter = mJSHolders.Iter(); !iter.Done(); iter.Next()) {
+    void* holder = iter.Key();
+    nsScriptObjectTracer*& tracer = iter.Data();
+    tracer->Trace(holder, JsGcTracer(), aTracer);
+  }
+}
+
+void
+CycleCollectedJSContext::AddJSHolder(void* aHolder, nsScriptObjectTracer* aTracer)
+{
+  MOZ_ASSERT(mJSContext);
+  mJSHolders.Put(aHolder, aTracer);
+}
+
+struct ClearJSHolder : public TraceCallbacks
+{
+  virtual void Trace(JS::Heap<JS::Value>* aPtr, const char*, void*) const override
+  {
+    aPtr->setUndefined();
+  }
+
+  virtual void Trace(JS::Heap<jsid>* aPtr, const char*, void*) const override
+  {
+    *aPtr = JSID_VOID;
+  }
+
+  virtual void Trace(JS::Heap<JSObject*>* aPtr, const char*, void*) const override
+  {
+    *aPtr = nullptr;
+  }
+
+  virtual void Trace(JSObject** aPtr, const char* aName,
+                     void* aClosure) const override
+  {
+    *aPtr = nullptr;
+  }
+
+  virtual void Trace(JS::TenuredHeap<JSObject*>* aPtr, const char*, void*) const override
+  {
+    *aPtr = nullptr;
+  }
+
+  virtual void Trace(JS::Heap<JSString*>* aPtr, const char*, void*) const override
+  {
+    *aPtr = nullptr;
+  }
+
+  virtual void Trace(JS::Heap<JSScript*>* aPtr, const char*, void*) const override
+  {
+    *aPtr = nullptr;
+  }
+
+  virtual void Trace(JS::Heap<JSFunction*>* aPtr, const char*, void*) const override
+  {
+    *aPtr = nullptr;
+  }
+};
+
+void
+CycleCollectedJSContext::RemoveJSHolder(void* aHolder)
+{
+  MOZ_ASSERT(mJSContext);
+
+  nsScriptObjectTracer* tracer = mJSHolders.Get(aHolder);
+  if (!tracer) {
+    return;
+  }
+  tracer->Trace(aHolder, ClearJSHolder(), nullptr);
+  mJSHolders.Remove(aHolder);
+}
+
+#ifdef DEBUG
+bool
+CycleCollectedJSContext::IsJSHolder(void* aHolder)
+{
+  MOZ_ASSERT(mJSContext);
+  return mJSHolders.Get(aHolder, nullptr);
+}
+
+static void
+AssertNoGcThing(JS::GCCellPtr aGCThing, const char* aName, void* aClosure)
+{
+  MOZ_ASSERT(!aGCThing);
+}
+
+void
+CycleCollectedJSContext::AssertNoObjectsToTrace(void* aPossibleJSHolder)
+{
+  MOZ_ASSERT(mJSContext);
+
+  nsScriptObjectTracer* tracer = mJSHolders.Get(aPossibleJSHolder);
+  if (tracer) {
+    tracer->Trace(aPossibleJSHolder, TraceCallbackFunc(AssertNoGcThing), nullptr);
+  }
+}
+#endif
+
+already_AddRefed<nsIException>
+CycleCollectedJSContext::GetPendingException() const
+{
+  MOZ_ASSERT(mJSContext);
+
+  nsCOMPtr<nsIException> out = mPendingException;
+  return out.forget();
+}
+
+void
+CycleCollectedJSContext::SetPendingException(nsIException* aException)
+{
+  MOZ_ASSERT(mJSContext);
+  mPendingException = aException;
+}
+
+std::queue<nsCOMPtr<nsIRunnable>>&
+CycleCollectedJSContext::GetPromiseMicroTaskQueue()
+{
+  MOZ_ASSERT(mJSContext);
+  return mPromiseMicroTaskQueue;
+}
+
+std::queue<nsCOMPtr<nsIRunnable>>&
+CycleCollectedJSContext::GetDebuggerPromiseMicroTaskQueue()
+{
+  MOZ_ASSERT(mJSContext);
+  return mDebuggerPromiseMicroTaskQueue;
+}
+
+nsCycleCollectionParticipant*
+CycleCollectedJSContext::GCThingParticipant()
+{
+  MOZ_ASSERT(mJSContext);
+  return &mGCThingCycleCollectorGlobal;
+}
+
+nsCycleCollectionParticipant*
+CycleCollectedJSContext::ZoneParticipant()
+{
+  MOZ_ASSERT(mJSContext);
+  return &mJSZoneCycleCollectorGlobal;
+}
+
+nsresult
+CycleCollectedJSContext::TraverseRoots(nsCycleCollectionNoteRootCallback& aCb)
+{
+  MOZ_ASSERT(mJSContext);
+
+  TraverseNativeRoots(aCb);
+
+  NoteWeakMapsTracer trc(mJSContext, aCb);
+  js::TraceWeakMaps(&trc);
+
+  return NS_OK;
+}
+
+bool
+CycleCollectedJSContext::UsefulToMergeZones() const
+{
+  return false;
+}
+
+void
+CycleCollectedJSContext::FixWeakMappingGrayBits() const
+{
+  MOZ_ASSERT(mJSContext);
+  MOZ_ASSERT(!JS::IsIncrementalGCInProgress(mJSContext),
+             "Don't call FixWeakMappingGrayBits during a GC.");
+  FixWeakMappingGrayBitsTracer fixer(mJSContext);
+  fixer.FixAll();
+}
+
+bool
+CycleCollectedJSContext::AreGCGrayBitsValid() const
+{
+  MOZ_ASSERT(mJSContext);
+  return js::AreGCGrayBitsValid(mJSContext);
+}
+
+void
+CycleCollectedJSContext::GarbageCollect(uint32_t aReason) const
+{
+  MOZ_ASSERT(mJSContext);
+
+  MOZ_ASSERT(aReason < JS::gcreason::NUM_REASONS);
+  JS::gcreason::Reason gcreason = static_cast<JS::gcreason::Reason>(aReason);
+
+  JS::PrepareForFullGC(mJSContext);
+  JS::GCForReason(mJSContext, GC_NORMAL, gcreason);
+}
+
+void
+CycleCollectedJSContext::JSObjectsTenured()
+{
+  MOZ_ASSERT(mJSContext);
+
+  for (auto iter = mNurseryObjects.Iter(); !iter.Done(); iter.Next()) {
+    nsWrapperCache* cache = iter.Get();
+    JSObject* wrapper = cache->GetWrapperPreserveColor();
+    MOZ_ASSERT(wrapper);
+    if (!JS::ObjectIsTenured(wrapper)) {
+      MOZ_ASSERT(!cache->PreservingWrapper());
+      const JSClass* jsClass = js::GetObjectJSClass(wrapper);
+      jsClass->doFinalize(nullptr, wrapper);
+    }
+  }
+
+#ifdef DEBUG
+for (auto iter = mPreservedNurseryObjects.Iter(); !iter.Done(); iter.Next()) {
+  MOZ_ASSERT(JS::ObjectIsTenured(iter.Get().get()));
+}
+#endif
+
+  mNurseryObjects.Clear();
+  mPreservedNurseryObjects.Clear();
+}
+
+void
+CycleCollectedJSContext::NurseryWrapperAdded(nsWrapperCache* aCache)
+{
+  MOZ_ASSERT(mJSContext);
+  MOZ_ASSERT(aCache);
+  MOZ_ASSERT(aCache->GetWrapperPreserveColor());
+  MOZ_ASSERT(!JS::ObjectIsTenured(aCache->GetWrapperPreserveColor()));
+  mNurseryObjects.InfallibleAppend(aCache);
+}
+
+void
+CycleCollectedJSContext::NurseryWrapperPreserved(JSObject* aWrapper)
+{
+  MOZ_ASSERT(mJSContext);
+
+  mPreservedNurseryObjects.InfallibleAppend(
+    JS::PersistentRooted<JSObject*>(mJSContext, aWrapper));
+}
+
+void
+CycleCollectedJSContext::DeferredFinalize(DeferredFinalizeAppendFunction aAppendFunc,
+                                          DeferredFinalizeFunction aFunc,
+                                          void* aThing)
+{
+  MOZ_ASSERT(mJSContext);
+
+  void* thingArray = nullptr;
+  bool hadThingArray = mDeferredFinalizerTable.Get(aFunc, &thingArray);
+
+  thingArray = aAppendFunc(thingArray, aThing);
+  if (!hadThingArray) {
+    mDeferredFinalizerTable.Put(aFunc, thingArray);
+  }
+}
+
+void
+CycleCollectedJSContext::DeferredFinalize(nsISupports* aSupports)
+{
+  MOZ_ASSERT(mJSContext);
+
+  typedef DeferredFinalizerImpl<nsISupports> Impl;
+  DeferredFinalize(Impl::AppendDeferredFinalizePointer, Impl::DeferredFinalize,
+                   aSupports);
+}
+
+void
+CycleCollectedJSContext::DumpJSHeap(FILE* aFile)
+{
+  js::DumpHeap(Context(), aFile, js::CollectNurseryBeforeDump);
+}
+
+void
+CycleCollectedJSContext::ProcessStableStateQueue()
+{
+  MOZ_ASSERT(mJSContext);
+  MOZ_RELEASE_ASSERT(!mDoingStableStates);
+  mDoingStableStates = true;
+
+  for (uint32_t i = 0; i < mStableStateEvents.Length(); ++i) {
+    nsCOMPtr<nsIRunnable> event = mStableStateEvents[i].forget();
+    event->Run();
+  }
+
+  mStableStateEvents.Clear();
+  mDoingStableStates = false;
+}
+
+void
+CycleCollectedJSContext::ProcessMetastableStateQueue(uint32_t aRecursionDepth)
+{
+  MOZ_ASSERT(mJSContext);
+  MOZ_RELEASE_ASSERT(!mDoingStableStates);
+  mDoingStableStates = true;
+
+  nsTArray<RunInMetastableStateData> localQueue = Move(mMetastableStateEvents);
+
+  for (uint32_t i = 0; i < localQueue.Length(); ++i)
+  {
+    RunInMetastableStateData& data = localQueue[i];
+    if (data.mRecursionDepth != aRecursionDepth) {
+      continue;
+    }
+
+    {
+      nsCOMPtr<nsIRunnable> runnable = data.mRunnable.forget();
+      runnable->Run();
+    }
+
+    localQueue.RemoveElementAt(i--);
+  }
+
+  // If the queue has events in it now, they were added from something we called,
+  // so they belong at the end of the queue.
+  localQueue.AppendElements(mMetastableStateEvents);
+  localQueue.SwapElements(mMetastableStateEvents);
+  mDoingStableStates = false;
+}
+
+void
+CycleCollectedJSContext::AfterProcessTask(uint32_t aRecursionDepth)
+{
+  MOZ_ASSERT(mJSContext);
+
+  // See HTML 6.1.4.2 Processing model
+
+  // Execute any events that were waiting for a microtask to complete.
+  // This is not (yet) in the spec.
+  ProcessMetastableStateQueue(aRecursionDepth);
+
+  // Step 4.1: Execute microtasks.
+  if (!mDisableMicroTaskCheckpoint) {
+    if (NS_IsMainThread()) {
+      nsContentUtils::PerformMainThreadMicroTaskCheckpoint();
+      Promise::PerformMicroTaskCheckpoint();
+    } else {
+      Promise::PerformWorkerMicroTaskCheckpoint();
+    }
+  }
+
+  // Step 4.2 Execute any events that were waiting for a stable state.
+  ProcessStableStateQueue();
+}
+
+void
+CycleCollectedJSContext::AfterProcessMicrotask()
+{
+  MOZ_ASSERT(mJSContext);
+  AfterProcessMicrotask(RecursionDepth());
+}
+
+void
+CycleCollectedJSContext::AfterProcessMicrotask(uint32_t aRecursionDepth)
+{
+  MOZ_ASSERT(mJSContext);
+
+  // Between microtasks, execute any events that were waiting for a microtask
+  // to complete.
+  ProcessMetastableStateQueue(aRecursionDepth);
+}
+
+uint32_t
+CycleCollectedJSContext::RecursionDepth()
+{
+  return mOwningThread->RecursionDepth();
+}
+
+void
+CycleCollectedJSContext::RunInStableState(already_AddRefed<nsIRunnable>&& aRunnable)
+{
+  MOZ_ASSERT(mJSContext);
+  mStableStateEvents.AppendElement(Move(aRunnable));
+}
+
+void
+CycleCollectedJSContext::RunInMetastableState(already_AddRefed<nsIRunnable>&& aRunnable)
+{
+  MOZ_ASSERT(mJSContext);
+
+  RunInMetastableStateData data;
+  data.mRunnable = aRunnable;
+
+  MOZ_ASSERT(mOwningThread);
+  data.mRecursionDepth = RecursionDepth();
+
+  // There must be an event running to get here.
+#ifndef MOZ_WIDGET_COCOA
+  MOZ_ASSERT(data.mRecursionDepth > mBaseRecursionDepth);
+#else
+  // XXX bug 1261143
+  // Recursion depth should be greater than mBaseRecursionDepth,
+  // or the runnable will stay in the queue forever.
+  if (data.mRecursionDepth <= mBaseRecursionDepth) {
+    data.mRecursionDepth = mBaseRecursionDepth + 1;
+  }
+#endif
+
+  mMetastableStateEvents.AppendElement(Move(data));
+}
+
+IncrementalFinalizeRunnable::IncrementalFinalizeRunnable(CycleCollectedJSContext* aCx,
+                                                         DeferredFinalizerTable& aFinalizers)
+  : mContext(aCx)
+  , mFinalizeFunctionToRun(0)
+  , mReleasing(false)
+{
+  for (auto iter = aFinalizers.Iter(); !iter.Done(); iter.Next()) {
+    DeferredFinalizeFunction& function = iter.Key();
+    void*& data = iter.Data();
+
+    DeferredFinalizeFunctionHolder* holder =
+      mDeferredFinalizeFunctions.AppendElement();
+    holder->run = function;
+    holder->data = data;
+
+    iter.Remove();
+  }
+}
+
+IncrementalFinalizeRunnable::~IncrementalFinalizeRunnable()
+{
+  MOZ_ASSERT(this != mContext->mFinalizeRunnable);
+}
+
+void
+IncrementalFinalizeRunnable::ReleaseNow(bool aLimited)
+{
+  if (mReleasing) {
+    NS_WARNING("Re-entering ReleaseNow");
+    return;
+  }
+  {
+    mozilla::AutoRestore<bool> ar(mReleasing);
+    mReleasing = true;
+    MOZ_ASSERT(mDeferredFinalizeFunctions.Length() != 0,
+               "We should have at least ReleaseSliceNow to run");
+    MOZ_ASSERT(mFinalizeFunctionToRun < mDeferredFinalizeFunctions.Length(),
+               "No more finalizers to run?");
+
+    TimeDuration sliceTime = TimeDuration::FromMilliseconds(SliceMillis);
+    TimeStamp started = TimeStamp::Now();
+    bool timeout = false;
+    do {
+      const DeferredFinalizeFunctionHolder& function =
+        mDeferredFinalizeFunctions[mFinalizeFunctionToRun];
+      if (aLimited) {
+        bool done = false;
+        while (!timeout && !done) {
+          /*
+           * We don't want to read the clock too often, so we try to
+           * release slices of 100 items.
+           */
+          done = function.run(100, function.data);
+          timeout = TimeStamp::Now() - started >= sliceTime;
+        }
+        if (done) {
+          ++mFinalizeFunctionToRun;
+        }
+        if (timeout) {
+          break;
+        }
+      } else {
+        while (!function.run(UINT32_MAX, function.data));
+        ++mFinalizeFunctionToRun;
+      }
+    } while (mFinalizeFunctionToRun < mDeferredFinalizeFunctions.Length());
+  }
+
+  if (mFinalizeFunctionToRun == mDeferredFinalizeFunctions.Length()) {
+    MOZ_ASSERT(mContext->mFinalizeRunnable == this);
+    mDeferredFinalizeFunctions.Clear();
+    // NB: This may delete this!
+    mContext->mFinalizeRunnable = nullptr;
+  }
+}
+
+NS_IMETHODIMP
+IncrementalFinalizeRunnable::Run()
+{
+  if (mContext->mFinalizeRunnable != this) {
+    /* These items were already processed synchronously in JSGC_END. */
+    MOZ_ASSERT(!mDeferredFinalizeFunctions.Length());
+    return NS_OK;
+  }
+
+  TimeStamp start = TimeStamp::Now();
+  ReleaseNow(true);
+
+  if (mDeferredFinalizeFunctions.Length()) {
+    nsresult rv = NS_DispatchToCurrentThread(this);
+    if (NS_FAILED(rv)) {
+      ReleaseNow(false);
+    }
+  }
+
+  uint32_t duration = (uint32_t)((TimeStamp::Now() - start).ToMilliseconds());
+  Telemetry::Accumulate(Telemetry::DEFERRED_FINALIZE_ASYNC, duration);
+
+  return NS_OK;
+}
+
+void
+CycleCollectedJSContext::FinalizeDeferredThings(DeferredFinalizeType aType)
+{
+  MOZ_ASSERT(mJSContext);
+
+  /*
+   * If the previous GC created a runnable to finalize objects
+   * incrementally, and if it hasn't finished yet, finish it now. We
+   * don't want these to build up. We also don't want to allow any
+   * existing incremental finalize runnables to run after a
+   * non-incremental GC, since they are often used to detect leaks.
+   */
+  if (mFinalizeRunnable) {
+    mFinalizeRunnable->ReleaseNow(false);
+    if (mFinalizeRunnable) {
+      // If we re-entered ReleaseNow, we couldn't delete mFinalizeRunnable and
+      // we need to just continue processing it.
+      return;
+    }
+  }
+
+  if (mDeferredFinalizerTable.Count() == 0) {
+    return;
+  }
+
+  mFinalizeRunnable = new IncrementalFinalizeRunnable(this,
+                                                      mDeferredFinalizerTable);
+
+  // Everything should be gone now.
+  MOZ_ASSERT(mDeferredFinalizerTable.Count() == 0);
+
+  if (aType == FinalizeIncrementally) {
+    NS_DispatchToCurrentThread(mFinalizeRunnable);
+  } else {
+    mFinalizeRunnable->ReleaseNow(false);
+    MOZ_ASSERT(!mFinalizeRunnable);
+  }
+}
+
+void
+CycleCollectedJSContext::AnnotateAndSetOutOfMemory(OOMState* aStatePtr,
+                                                   OOMState aNewState)
+{
+  MOZ_ASSERT(mJSContext);
+
+  *aStatePtr = aNewState;
+#ifdef MOZ_CRASHREPORTER
+  CrashReporter::AnnotateCrashReport(aStatePtr == &mOutOfMemoryState
+                                     ? NS_LITERAL_CSTRING("JSOutOfMemory")
+                                     : NS_LITERAL_CSTRING("JSLargeAllocationFailure"),
+                                     aNewState == OOMState::Reporting
+                                     ? NS_LITERAL_CSTRING("Reporting")
+                                     : aNewState == OOMState::Reported
+                                     ? NS_LITERAL_CSTRING("Reported")
+                                     : NS_LITERAL_CSTRING("Recovered"));
+#endif
+}
+
+void
+CycleCollectedJSContext::OnGC(JSGCStatus aStatus)
+{
+  MOZ_ASSERT(mJSContext);
+
+  switch (aStatus) {
+    case JSGC_BEGIN:
+      nsCycleCollector_prepareForGarbageCollection();
+      mZonesWaitingForGC.Clear();
+      break;
+    case JSGC_END: {
+#ifdef MOZ_CRASHREPORTER
+      if (mOutOfMemoryState == OOMState::Reported) {
+        AnnotateAndSetOutOfMemory(&mOutOfMemoryState, OOMState::Recovered);
+      }
+      if (mLargeAllocationFailureState == OOMState::Reported) {
+        AnnotateAndSetOutOfMemory(&mLargeAllocationFailureState, OOMState::Recovered);
+      }
+#endif
+
+      // Do any deferred finalization of native objects.
+      FinalizeDeferredThings(JS::WasIncrementalGC(mJSContext) ? FinalizeIncrementally :
+                                                                FinalizeNow);
+      break;
+    }
+    default:
+      MOZ_CRASH();
+  }
+
+  CustomGCCallback(aStatus);
+}
+
+void
+CycleCollectedJSContext::OnOutOfMemory()
+{
+  MOZ_ASSERT(mJSContext);
+
+  AnnotateAndSetOutOfMemory(&mOutOfMemoryState, OOMState::Reporting);
+  CustomOutOfMemoryCallback();
+  AnnotateAndSetOutOfMemory(&mOutOfMemoryState, OOMState::Reported);
+}
+
+void
+CycleCollectedJSContext::OnLargeAllocationFailure()
+{
+  MOZ_ASSERT(mJSContext);
+
+  AnnotateAndSetOutOfMemory(&mLargeAllocationFailureState, OOMState::Reporting);
+  CustomLargeAllocationFailureCallback();
+  AnnotateAndSetOutOfMemory(&mLargeAllocationFailureState, OOMState::Reported);
+}
+
+void
+CycleCollectedJSContext::PrepareWaitingZonesForGC()
+{
+  if (mZonesWaitingForGC.Count() == 0) {
+    JS::PrepareForFullGC(Context());
+  } else {
+    for (auto iter = mZonesWaitingForGC.Iter(); !iter.Done(); iter.Next()) {
+      JS::PrepareZoneForGC(iter.Get()->GetKey());
+    }
+    mZonesWaitingForGC.Clear();
+  }
+}
+
+void
+CycleCollectedJSContext::DispatchToMicroTask(already_AddRefed<nsIRunnable> aRunnable)
+{
+  RefPtr<nsIRunnable> runnable(aRunnable);
+
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(runnable);
+
+  mPromiseMicroTaskQueue.push(runnable.forget());
+}
+
+void
+CycleCollectedJSContext::EnvironmentPreparer::invoke(JS::HandleObject scope,
+                                                     js::ScriptEnvironmentPreparer::Closure& closure)
+{
+  nsIGlobalObject* global = xpc::NativeGlobal(scope);
+
+  // Not much we can do if we simply don't have a usable global here...
+  NS_ENSURE_TRUE_VOID(global && global->GetGlobalJSObject());
+
+  AutoEntryScript aes(global, "JS-engine-initiated execution");
+
+  MOZ_ASSERT(!JS_IsExceptionPending(aes.cx()));
+
+  DebugOnly<bool> ok = closure(aes.cx());
+
+  MOZ_ASSERT_IF(ok, !JS_IsExceptionPending(aes.cx()));
+
+  // The AutoEntryScript will check for JS_IsExceptionPending on the
+  // JSContext and report it as needed as it comes off the stack.
+}
diff --git a/xpcom/base/CycleCollectedJSContext.h b/xpcom/base/CycleCollectedJSContext.h
new file mode 100644
index 000000000..9415634b8
--- /dev/null
+++ b/xpcom/base/CycleCollectedJSContext.h
@@ -0,0 +1,494 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_CycleCollectedJSContext_h__
+#define mozilla_CycleCollectedJSContext_h__
+
+#include <queue>
+
+#include "mozilla/DeferredFinalize.h"
+#include "mozilla/mozalloc.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/SegmentedVector.h"
+#include "jsapi.h"
+#include "jsfriendapi.h"
+
+#include "nsCycleCollectionParticipant.h"
+#include "nsDataHashtable.h"
+#include "nsHashKeys.h"
+#include "nsTArray.h"
+#include "nsTHashtable.h"
+
+class nsCycleCollectionNoteRootCallback;
+class nsIException;
+class nsIRunnable;
+class nsThread;
+class nsWrapperCache;
+
+namespace js {
+struct Class;
+} // namespace js
+
+namespace mozilla {
+
+class JSGCThingParticipant: public nsCycleCollectionParticipant
+{
+public:
+  NS_IMETHOD_(void) Root(void*) override
+  {
+    MOZ_ASSERT(false, "Don't call Root on GC things");
+  }
+
+  NS_IMETHOD_(void) Unlink(void*) override
+  {
+    MOZ_ASSERT(false, "Don't call Unlink on GC things, as they may be dead");
+  }
+
+  NS_IMETHOD_(void) Unroot(void*) override
+  {
+    MOZ_ASSERT(false, "Don't call Unroot on GC things, as they may be dead");
+  }
+
+  NS_IMETHOD_(void) DeleteCycleCollectable(void* aPtr) override
+  {
+    MOZ_ASSERT(false, "Can't directly delete a cycle collectable GC thing");
+  }
+
+  NS_IMETHOD Traverse(void* aPtr, nsCycleCollectionTraversalCallback& aCb)
+    override;
+
+  NS_DECL_CYCLE_COLLECTION_CLASS_NAME_METHOD(JSGCThingParticipant)
+};
+
+class JSZoneParticipant : public nsCycleCollectionParticipant
+{
+public:
+  constexpr JSZoneParticipant(): nsCycleCollectionParticipant()
+  {
+  }
+
+  NS_IMETHOD_(void) Root(void*) override
+  {
+    MOZ_ASSERT(false, "Don't call Root on GC things");
+  }
+
+  NS_IMETHOD_(void) Unlink(void*) override
+  {
+    MOZ_ASSERT(false, "Don't call Unlink on GC things, as they may be dead");
+  }
+
+  NS_IMETHOD_(void) Unroot(void*) override
+  {
+    MOZ_ASSERT(false, "Don't call Unroot on GC things, as they may be dead");
+  }
+
+  NS_IMETHOD_(void) DeleteCycleCollectable(void*) override
+  {
+    MOZ_ASSERT(false, "Can't directly delete a cycle collectable GC thing");
+  }
+
+  NS_IMETHOD Traverse(void* aPtr, nsCycleCollectionTraversalCallback& aCb)
+    override;
+
+  NS_DECL_CYCLE_COLLECTION_CLASS_NAME_METHOD(JSZoneParticipant)
+};
+
+class IncrementalFinalizeRunnable;
+
+// Contains various stats about the cycle collection.
+struct CycleCollectorResults
+{
+  CycleCollectorResults()
+  {
+    // Initialize here so when we increment mNumSlices the first time we're
+    // not using uninitialized memory.
+    Init();
+  }
+
+  void Init()
+  {
+    mForcedGC = false;
+    mMergedZones = false;
+    mAnyManual = false;
+    mVisitedRefCounted = 0;
+    mVisitedGCed = 0;
+    mFreedRefCounted = 0;
+    mFreedGCed = 0;
+    mFreedJSZones = 0;
+    mNumSlices = 1;
+    // mNumSlices is initialized to one, because we call Init() after the
+    // per-slice increment of mNumSlices has already occurred.
+  }
+
+  bool mForcedGC;
+  bool mMergedZones;
+  bool mAnyManual; // true if any slice of the CC was manually triggered, or at shutdown.
+  uint32_t mVisitedRefCounted;
+  uint32_t mVisitedGCed;
+  uint32_t mFreedRefCounted;
+  uint32_t mFreedGCed;
+  uint32_t mFreedJSZones;
+  uint32_t mNumSlices;
+};
+
+class CycleCollectedJSContext
+{
+  friend class JSGCThingParticipant;
+  friend class JSZoneParticipant;
+  friend class IncrementalFinalizeRunnable;
+protected:
+  CycleCollectedJSContext();
+  virtual ~CycleCollectedJSContext();
+
+  MOZ_IS_CLASS_INIT
+  nsresult Initialize(JSContext* aParentContext,
+                      uint32_t aMaxBytes,
+                      uint32_t aMaxNurseryBytes);
+
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
+  void UnmarkSkippableJSHolders();
+
+  virtual void
+  TraverseAdditionalNativeRoots(nsCycleCollectionNoteRootCallback& aCb) {}
+  virtual void TraceAdditionalNativeGrayRoots(JSTracer* aTracer) {}
+
+  virtual void CustomGCCallback(JSGCStatus aStatus) {}
+  virtual void CustomOutOfMemoryCallback() {}
+  virtual void CustomLargeAllocationFailureCallback() {}
+
+  std::queue<nsCOMPtr<nsIRunnable>> mPromiseMicroTaskQueue;
+  std::queue<nsCOMPtr<nsIRunnable>> mDebuggerPromiseMicroTaskQueue;
+
+private:
+  void
+  DescribeGCThing(bool aIsMarked, JS::GCCellPtr aThing,
+                  nsCycleCollectionTraversalCallback& aCb) const;
+
+  virtual bool
+  DescribeCustomObjects(JSObject* aObject, const js::Class* aClasp,
+                        char (&aName)[72]) const
+  {
+    return false; // We did nothing.
+  }
+
+  void
+  NoteGCThingJSChildren(JS::GCCellPtr aThing,
+                        nsCycleCollectionTraversalCallback& aCb) const;
+
+  void
+  NoteGCThingXPCOMChildren(const js::Class* aClasp, JSObject* aObj,
+                           nsCycleCollectionTraversalCallback& aCb) const;
+
+  virtual bool
+  NoteCustomGCThingXPCOMChildren(const js::Class* aClasp, JSObject* aObj,
+                                 nsCycleCollectionTraversalCallback& aCb) const
+  {
+    return false; // We did nothing.
+  }
+
+  enum TraverseSelect {
+    TRAVERSE_CPP,
+    TRAVERSE_FULL
+  };
+
+  void
+  TraverseGCThing(TraverseSelect aTs, JS::GCCellPtr aThing,
+                  nsCycleCollectionTraversalCallback& aCb);
+
+  void
+  TraverseZone(JS::Zone* aZone, nsCycleCollectionTraversalCallback& aCb);
+
+  static void
+  TraverseObjectShim(void* aData, JS::GCCellPtr aThing);
+
+  void TraverseNativeRoots(nsCycleCollectionNoteRootCallback& aCb);
+
+  static void TraceBlackJS(JSTracer* aTracer, void* aData);
+  static void TraceGrayJS(JSTracer* aTracer, void* aData);
+  static void GCCallback(JSContext* aContext, JSGCStatus aStatus, void* aData);
+  static void GCSliceCallback(JSContext* aContext, JS::GCProgress aProgress,
+                              const JS::GCDescription& aDesc);
+  static void GCNurseryCollectionCallback(JSContext* aContext,
+                                          JS::GCNurseryProgress aProgress,
+                                          JS::gcreason::Reason aReason);
+  static void OutOfMemoryCallback(JSContext* aContext, void* aData);
+  static void LargeAllocationFailureCallback(void* aData);
+  static bool ContextCallback(JSContext* aCx, unsigned aOperation,
+                              void* aData);
+  static JSObject* GetIncumbentGlobalCallback(JSContext* aCx);
+  static bool EnqueuePromiseJobCallback(JSContext* aCx,
+                                        JS::HandleObject aJob,
+                                        JS::HandleObject aAllocationSite,
+                                        JS::HandleObject aIncumbentGlobal,
+                                        void* aData);
+#ifdef SPIDERMONKEY_PROMISE
+  static void PromiseRejectionTrackerCallback(JSContext* aCx,
+                                              JS::HandleObject aPromise,
+                                              PromiseRejectionHandlingState state,
+                                              void* aData);
+#endif // SPIDERMONKEY_PROMISE
+
+  virtual void TraceNativeBlackRoots(JSTracer* aTracer) { };
+  void TraceNativeGrayRoots(JSTracer* aTracer);
+
+  void AfterProcessMicrotask(uint32_t aRecursionDepth);
+public:
+  void ProcessStableStateQueue();
+private:
+  void ProcessMetastableStateQueue(uint32_t aRecursionDepth);
+
+public:
+  enum DeferredFinalizeType {
+    FinalizeIncrementally,
+    FinalizeNow,
+  };
+
+  void FinalizeDeferredThings(DeferredFinalizeType aType);
+
+  // Two conditions, JSOutOfMemory and JSLargeAllocationFailure, are noted in
+  // crash reports. Here are the values that can appear in the reports:
+  enum class OOMState : uint32_t {
+    // The condition has never happened. No entry appears in the crash report.
+    OK,
+
+    // We are currently reporting the given condition.
+    //
+    // Suppose a crash report contains "JSLargeAllocationFailure:
+    // Reporting". This means we crashed while executing memory-pressure
+    // observers, trying to shake loose some memory. The large allocation in
+    // question did not return null: it is still on the stack. Had we not
+    // crashed, it would have been retried.
+    Reporting,
+
+    // The condition has been reported since the last GC.
+    //
+    // If a crash report contains "JSOutOfMemory: Reported", that means a small
+    // allocation failed, and then we crashed, probably due to buggy
+    // error-handling code that ran after allocation returned null.
+    //
+    // This contrasts with "Reporting" which means that no error-handling code
+    // had executed yet.
+    Reported,
+
+    // The condition has happened, but a GC cycle ended since then.
+    //
+    // GC is taken as a proxy for "we've been banging on the heap a good bit
+    // now and haven't crashed; the OOM was probably handled correctly".
+    Recovered
+  };
+
+private:
+  void AnnotateAndSetOutOfMemory(OOMState* aStatePtr, OOMState aNewState);
+  void OnGC(JSGCStatus aStatus);
+  void OnOutOfMemory();
+  void OnLargeAllocationFailure();
+
+public:
+  void AddJSHolder(void* aHolder, nsScriptObjectTracer* aTracer);
+  void RemoveJSHolder(void* aHolder);
+#ifdef DEBUG
+  bool IsJSHolder(void* aHolder);
+  void AssertNoObjectsToTrace(void* aPossibleJSHolder);
+#endif
+
+  already_AddRefed<nsIException> GetPendingException() const;
+  void SetPendingException(nsIException* aException);
+
+  std::queue<nsCOMPtr<nsIRunnable>>& GetPromiseMicroTaskQueue();
+  std::queue<nsCOMPtr<nsIRunnable>>& GetDebuggerPromiseMicroTaskQueue();
+
+  nsCycleCollectionParticipant* GCThingParticipant();
+  nsCycleCollectionParticipant* ZoneParticipant();
+
+  nsresult TraverseRoots(nsCycleCollectionNoteRootCallback& aCb);
+  virtual bool UsefulToMergeZones() const;
+  void FixWeakMappingGrayBits() const;
+  bool AreGCGrayBitsValid() const;
+  void GarbageCollect(uint32_t aReason) const;
+
+  void NurseryWrapperAdded(nsWrapperCache* aCache);
+  void NurseryWrapperPreserved(JSObject* aWrapper);
+  void JSObjectsTenured();
+
+  void DeferredFinalize(DeferredFinalizeAppendFunction aAppendFunc,
+                        DeferredFinalizeFunction aFunc,
+                        void* aThing);
+  void DeferredFinalize(nsISupports* aSupports);
+
+  void DumpJSHeap(FILE* aFile);
+
+  virtual void PrepareForForgetSkippable() = 0;
+  virtual void BeginCycleCollectionCallback() = 0;
+  virtual void EndCycleCollectionCallback(CycleCollectorResults& aResults) = 0;
+  virtual void DispatchDeferredDeletion(bool aContinuation, bool aPurge = false) = 0;
+
+  JSContext* Context() const
+  {
+    MOZ_ASSERT(mJSContext);
+    return mJSContext;
+  }
+
+  JS::RootingContext* RootingCx() const
+  {
+    MOZ_ASSERT(mJSContext);
+    return JS::RootingContext::get(mJSContext);
+  }
+
+  bool MicroTaskCheckpointDisabled() const
+  {
+    return mDisableMicroTaskCheckpoint;
+  }
+
+  void DisableMicroTaskCheckpoint(bool aDisable)
+  {
+    mDisableMicroTaskCheckpoint = aDisable;
+  }
+
+  class MOZ_RAII AutoDisableMicroTaskCheckpoint
+  {
+    public:
+    AutoDisableMicroTaskCheckpoint()
+    : mCCJSCX(CycleCollectedJSContext::Get())
+    {
+      mOldValue = mCCJSCX->MicroTaskCheckpointDisabled();
+      mCCJSCX->DisableMicroTaskCheckpoint(true);
+    }
+
+    ~AutoDisableMicroTaskCheckpoint()
+    {
+      mCCJSCX->DisableMicroTaskCheckpoint(mOldValue);
+    }
+
+    CycleCollectedJSContext* mCCJSCX;
+    bool mOldValue;
+  };
+
+protected:
+  JSContext* MaybeContext() const { return mJSContext; }
+
+public:
+  // nsThread entrypoints
+  virtual void BeforeProcessTask(bool aMightBlock) { };
+  virtual void AfterProcessTask(uint32_t aRecursionDepth);
+
+  // microtask processor entry point
+  void AfterProcessMicrotask();
+
+  uint32_t RecursionDepth();
+
+  // Run in stable state (call through nsContentUtils)
+  void RunInStableState(already_AddRefed<nsIRunnable>&& aRunnable);
+  // This isn't in the spec at all yet, but this gets the behavior we want for IDB.
+  // Runs after the current microtask completes.
+  void RunInMetastableState(already_AddRefed<nsIRunnable>&& aRunnable);
+
+  // Get the current thread's CycleCollectedJSContext.  Returns null if there
+  // isn't one.
+  static CycleCollectedJSContext* Get();
+
+  // Add aZone to the set of zones waiting for a GC.
+  void AddZoneWaitingForGC(JS::Zone* aZone)
+  {
+    mZonesWaitingForGC.PutEntry(aZone);
+  }
+
+  // Prepare any zones for GC that have been passed to AddZoneWaitingForGC()
+  // since the last GC or since the last call to PrepareWaitingZonesForGC(),
+  // whichever was most recent. If there were no such zones, prepare for a
+  // full GC.
+  void PrepareWaitingZonesForGC();
+
+  // Queue an async microtask to the current main or worker thread.
+  virtual void DispatchToMicroTask(already_AddRefed<nsIRunnable> aRunnable);
+
+  // Storage for watching rejected promises waiting for some client to
+  // consume their rejection.
+#ifdef SPIDERMONKEY_PROMISE
+  // Promises in this list have been rejected in the last turn of the
+  // event loop without the rejection being handled.
+  // Note that this can contain nullptrs in place of promises removed because
+  // they're consumed before it'd be reported.
+  JS::PersistentRooted<JS::GCVector<JSObject*, 0, js::SystemAllocPolicy>> mUncaughtRejections;
+
+  // Promises in this list have previously been reported as rejected
+  // (because they were in the above list), but the rejection was handled
+  // in the last turn of the event loop.
+  JS::PersistentRooted<JS::GCVector<JSObject*, 0, js::SystemAllocPolicy>> mConsumedRejections;
+#else
+  // We store values as `nsISupports` to avoid adding compile-time dependencies
+  // from xpcom to dom/promise, but they can really only have a single concrete
+  // type.
+  nsTArray<nsCOMPtr<nsISupports /* Promise */>> mUncaughtRejections;
+  nsTArray<nsCOMPtr<nsISupports /* Promise */ >> mConsumedRejections;
+#endif // SPIDERMONKEY_PROMISE
+  nsTArray<nsCOMPtr<nsISupports /* UncaughtRejectionObserver */ >> mUncaughtRejectionObservers;
+
+private:
+  JSGCThingParticipant mGCThingCycleCollectorGlobal;
+
+  JSZoneParticipant mJSZoneCycleCollectorGlobal;
+
+  JSContext* mJSContext;
+
+  JS::GCSliceCallback mPrevGCSliceCallback;
+  JS::GCNurseryCollectionCallback mPrevGCNurseryCollectionCallback;
+
+  nsDataHashtable<nsPtrHashKey<void>, nsScriptObjectTracer*> mJSHolders;
+
+  typedef nsDataHashtable<nsFuncPtrHashKey<DeferredFinalizeFunction>, void*>
+    DeferredFinalizerTable;
+  DeferredFinalizerTable mDeferredFinalizerTable;
+
+  RefPtr<IncrementalFinalizeRunnable> mFinalizeRunnable;
+
+  nsCOMPtr<nsIException> mPendingException;
+  nsThread* mOwningThread; // Manual refcounting to avoid include hell.
+
+  struct RunInMetastableStateData
+  {
+    nsCOMPtr<nsIRunnable> mRunnable;
+    uint32_t mRecursionDepth;
+  };
+
+  nsTArray<nsCOMPtr<nsIRunnable>> mStableStateEvents;
+  nsTArray<RunInMetastableStateData> mMetastableStateEvents;
+  uint32_t mBaseRecursionDepth;
+  bool mDoingStableStates;
+
+  bool mDisableMicroTaskCheckpoint;
+
+  OOMState mOutOfMemoryState;
+  OOMState mLargeAllocationFailureState;
+
+  static const size_t kSegmentSize = 512;
+  SegmentedVector<nsWrapperCache*, kSegmentSize, InfallibleAllocPolicy>
+    mNurseryObjects;
+  SegmentedVector<JS::PersistentRooted<JSObject*>, kSegmentSize,
+                  InfallibleAllocPolicy>
+    mPreservedNurseryObjects;
+
+  nsTHashtable<nsPtrHashKey<JS::Zone>> mZonesWaitingForGC;
+
+  struct EnvironmentPreparer : public js::ScriptEnvironmentPreparer {
+    void invoke(JS::HandleObject scope, Closure& closure) override;
+  };
+  EnvironmentPreparer mEnvironmentPreparer;
+};
+
+void TraceScriptHolder(nsISupports* aHolder, JSTracer* aTracer);
+
+// Returns true if the JS::TraceKind is one the cycle collector cares about.
+inline bool AddToCCKind(JS::TraceKind aKind)
+{
+  return aKind == JS::TraceKind::Object || aKind == JS::TraceKind::Script || aKind == JS::TraceKind::Scope;
+}
+
+bool
+GetBuildId(JS::BuildIdCharVector* aBuildID);
+
+} // namespace mozilla
+
+#endif // mozilla_CycleCollectedJSContext_h__
diff --git a/xpcom/base/Debug.cpp b/xpcom/base/Debug.cpp
new file mode 100644
index 000000000..cc5272da0
--- /dev/null
+++ b/xpcom/base/Debug.cpp
@@ -0,0 +1,23 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Debug.h"
+
+#ifdef XP_WIN
+#include <windows.h>
+#endif
+
+#ifdef XP_WIN
+
+void
+mozilla::PrintToDebugger(const char* aStr)
+{
+  if (::IsDebuggerPresent()) {
+    ::OutputDebugStringA(aStr);
+  }
+}
+
+#endif
diff --git a/xpcom/base/Debug.h b/xpcom/base/Debug.h
new file mode 100644
index 000000000..2479799ae
--- /dev/null
+++ b/xpcom/base/Debug.h
@@ -0,0 +1,21 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_Debug_h__
+#define mozilla_Debug_h__
+
+namespace mozilla {
+
+#ifdef XP_WIN
+
+// Print aStr to a debugger if the debugger is attached.
+void PrintToDebugger(const char* aStr);
+
+#endif
+
+} // namespace mozilla
+
+#endif // mozilla_Debug_h__
diff --git a/xpcom/base/DebuggerOnGCRunnable.cpp b/xpcom/base/DebuggerOnGCRunnable.cpp
new file mode 100644
index 000000000..96f4cddcb
--- /dev/null
+++ b/xpcom/base/DebuggerOnGCRunnable.cpp
@@ -0,0 +1,47 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/DebuggerOnGCRunnable.h"
+
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/CycleCollectedJSContext.h"
+#include "mozilla/Move.h"
+#include "js/Debug.h"
+
+namespace mozilla {
+
+/* static */ nsresult
+DebuggerOnGCRunnable::Enqueue(JSContext* aCx, const JS::GCDescription& aDesc)
+{
+  auto gcEvent = aDesc.toGCEvent(aCx);
+  if (!gcEvent) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  RefPtr<DebuggerOnGCRunnable> runOnGC =
+    new DebuggerOnGCRunnable(Move(gcEvent));
+  return NS_DispatchToCurrentThread(runOnGC);
+}
+
+NS_IMETHODIMP
+DebuggerOnGCRunnable::Run()
+{
+  AutoJSAPI jsapi;
+  jsapi.Init();
+  if (!JS::dbg::FireOnGarbageCollectionHook(jsapi.cx(), Move(mGCData))) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  return NS_OK;
+}
+
+nsresult
+DebuggerOnGCRunnable::Cancel()
+{
+  mGCData = nullptr;
+  return NS_OK;
+}
+
+} // namespace mozilla
diff --git a/xpcom/base/DebuggerOnGCRunnable.h b/xpcom/base/DebuggerOnGCRunnable.h
new file mode 100644
index 000000000..8f9621613
--- /dev/null
+++ b/xpcom/base/DebuggerOnGCRunnable.h
@@ -0,0 +1,35 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_DebuggerOnGCRunnable_h
+#define mozilla_DebuggerOnGCRunnable_h
+
+#include "nsThreadUtils.h"
+#include "js/GCAPI.h"
+#include "mozilla/Move.h"
+#include "mozilla/UniquePtr.h"
+
+namespace mozilla {
+
+// Runnable to fire the SpiderMonkey Debugger API's onGarbageCollection hook.
+class DebuggerOnGCRunnable : public CancelableRunnable
+{
+  JS::dbg::GarbageCollectionEvent::Ptr mGCData;
+
+  explicit DebuggerOnGCRunnable(JS::dbg::GarbageCollectionEvent::Ptr&& aGCData)
+    : mGCData(Move(aGCData))
+  { }
+
+public:
+  static nsresult Enqueue(JSContext* aCx, const JS::GCDescription& aDesc);
+
+  NS_DECL_NSIRUNNABLE
+  nsresult Cancel() override;
+};
+
+} // namespace mozilla
+
+#endif // ifdef mozilla_dom_DebuggerOnGCRunnable_h
diff --git a/xpcom/base/DeferredFinalize.cpp b/xpcom/base/DeferredFinalize.cpp
new file mode 100644
index 000000000..b9a71b81c
--- /dev/null
+++ b/xpcom/base/DeferredFinalize.cpp
@@ -0,0 +1,28 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/DeferredFinalize.h"
+
+#include "mozilla/Assertions.h"
+#include "mozilla/CycleCollectedJSContext.h"
+
+void
+mozilla::DeferredFinalize(nsISupports* aSupports)
+{
+  CycleCollectedJSContext* cx = CycleCollectedJSContext::Get();
+  MOZ_ASSERT(cx, "Should have a CycleCollectedJSContext by now");
+  cx->DeferredFinalize(aSupports);
+}
+
+void
+mozilla::DeferredFinalize(DeferredFinalizeAppendFunction aAppendFunc,
+                          DeferredFinalizeFunction aFunc,
+                          void* aThing)
+{
+  CycleCollectedJSContext* cx = CycleCollectedJSContext::Get();
+  MOZ_ASSERT(cx, "Should have a CycleCollectedJSContext by now");
+  cx->DeferredFinalize(aAppendFunc, aFunc, aThing);
+}
diff --git a/xpcom/base/DeferredFinalize.h b/xpcom/base/DeferredFinalize.h
new file mode 100644
index 000000000..7d9c58881
--- /dev/null
+++ b/xpcom/base/DeferredFinalize.h
@@ -0,0 +1,33 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_DeferredFinalize_h
+#define mozilla_DeferredFinalize_h
+
+class nsISupports;
+
+namespace mozilla {
+
+// Called back from DeferredFinalize.  Should add 'thing' to the array of smart
+// pointers in 'pointers', creating the array if 'pointers' is null, and return
+// the array.
+typedef void* (*DeferredFinalizeAppendFunction)(void* aPointers, void* aThing);
+
+// Called to finalize a number of objects. Slice is the number of objects to
+// finalize. The return value indicates whether it finalized all objects in the
+// buffer. If it returns true, the function will not be called again, so the
+// function should free aData.
+typedef bool (*DeferredFinalizeFunction)(uint32_t aSlice, void* aData);
+
+void DeferredFinalize(DeferredFinalizeAppendFunction aAppendFunc,
+                      DeferredFinalizeFunction aFunc,
+                      void* aThing);
+
+void DeferredFinalize(nsISupports* aSupports);
+
+} // namespace mozilla
+
+#endif // mozilla_DeferredFinalize_h
diff --git a/xpcom/base/ErrorList.h b/xpcom/base/ErrorList.h
new file mode 100644
index 000000000..cfa461fe4
--- /dev/null
+++ b/xpcom/base/ErrorList.h
@@ -0,0 +1,1026 @@
+// IWYU pragma: private, include "nsError.h"
+/* Helper file for nsError.h, via preprocessor magic */
+  /* Standard "it worked" return value */
+  ERROR(NS_OK,  0),
+
+  /* ======================================================================= */
+  /* Core errors, not part of any modules */
+  /* ======================================================================= */
+  ERROR(NS_ERROR_BASE,                          0xC1F30000),
+  /* Returned when an instance is not initialized */
+  ERROR(NS_ERROR_NOT_INITIALIZED,               NS_ERROR_BASE + 1),
+  /* Returned when an instance is already initialized */
+  ERROR(NS_ERROR_ALREADY_INITIALIZED,           NS_ERROR_BASE + 2),
+  /* Returned by a not implemented function */
+  ERROR(NS_ERROR_NOT_IMPLEMENTED,               0x80004001),
+  /* Returned when a given interface is not supported. */
+  ERROR(NS_NOINTERFACE,                         0x80004002),
+  ERROR(NS_ERROR_NO_INTERFACE,                  NS_NOINTERFACE),
+  /* Returned when a function aborts */
+  ERROR(NS_ERROR_ABORT,                         0x80004004),
+  /* Returned when a function fails */
+  ERROR(NS_ERROR_FAILURE,                       0x80004005),
+  /* Returned when an unexpected error occurs */
+  ERROR(NS_ERROR_UNEXPECTED,                    0x8000ffff),
+  /* Returned when a memory allocation fails */
+  ERROR(NS_ERROR_OUT_OF_MEMORY,                 0x8007000e),
+  /* Returned when an illegal value is passed */
+  ERROR(NS_ERROR_ILLEGAL_VALUE,                 0x80070057),
+  ERROR(NS_ERROR_INVALID_ARG,                   NS_ERROR_ILLEGAL_VALUE),
+  ERROR(NS_ERROR_INVALID_POINTER,               NS_ERROR_INVALID_ARG),
+  ERROR(NS_ERROR_NULL_POINTER,                  NS_ERROR_INVALID_ARG),
+  /* Returned when a class doesn't allow aggregation */
+  ERROR(NS_ERROR_NO_AGGREGATION,                0x80040110),
+  /* Returned when an operation can't complete due to an unavailable resource */
+  ERROR(NS_ERROR_NOT_AVAILABLE,                 0x80040111),
+  /* Returned when a class is not registered */
+  ERROR(NS_ERROR_FACTORY_NOT_REGISTERED,        0x80040154),
+  /* Returned when a class cannot be registered, but may be tried again later */
+  ERROR(NS_ERROR_FACTORY_REGISTER_AGAIN,        0x80040155),
+  /* Returned when a dynamically loaded factory couldn't be found */
+  ERROR(NS_ERROR_FACTORY_NOT_LOADED,            0x800401f8),
+  /* Returned when a factory doesn't support signatures */
+  ERROR(NS_ERROR_FACTORY_NO_SIGNATURE_SUPPORT,  NS_ERROR_BASE + 0x101),
+  /* Returned when a factory already is registered */
+  ERROR(NS_ERROR_FACTORY_EXISTS,                NS_ERROR_BASE + 0x100),
+
+
+  /* ======================================================================= */
+  /* 1: NS_ERROR_MODULE_XPCOM */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_XPCOM
+  /* Result codes used by nsIVariant */
+  ERROR(NS_ERROR_CANNOT_CONVERT_DATA,       FAILURE(1)),
+  ERROR(NS_ERROR_OBJECT_IS_IMMUTABLE,       FAILURE(2)),
+  ERROR(NS_ERROR_LOSS_OF_SIGNIFICANT_DATA,  FAILURE(3)),
+  /* Result code used by nsIThreadManager */
+  ERROR(NS_ERROR_NOT_SAME_THREAD,           FAILURE(4)),
+  /* Various operations are not permitted during XPCOM shutdown and will fail
+   * with this exception. */
+  ERROR(NS_ERROR_ILLEGAL_DURING_SHUTDOWN,   FAILURE(30)),
+  ERROR(NS_ERROR_SERVICE_NOT_AVAILABLE,     FAILURE(22)),
+
+  ERROR(NS_SUCCESS_LOSS_OF_INSIGNIFICANT_DATA,  SUCCESS(1)),
+  /* Used by nsCycleCollectionParticipant */
+  ERROR(NS_SUCCESS_INTERRUPTED_TRAVERSE,        SUCCESS(2)),
+  /* DEPRECATED */
+  ERROR(NS_ERROR_SERVICE_NOT_FOUND,             SUCCESS(22)),
+  /* DEPRECATED */
+  ERROR(NS_ERROR_SERVICE_IN_USE,                SUCCESS(23)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 2: NS_ERROR_MODULE_BASE */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_BASE
+  /* I/O Errors */
+
+  /*  Stream closed */
+  ERROR(NS_BASE_STREAM_CLOSED,          FAILURE(2)),
+  /*  Error from the operating system */
+  ERROR(NS_BASE_STREAM_OSERROR,         FAILURE(3)),
+  /*  Illegal arguments */
+  ERROR(NS_BASE_STREAM_ILLEGAL_ARGS,    FAILURE(4)),
+  /*  For unichar streams */
+  ERROR(NS_BASE_STREAM_NO_CONVERTER,    FAILURE(5)),
+  /*  For unichar streams */
+  ERROR(NS_BASE_STREAM_BAD_CONVERSION,  FAILURE(6)),
+  ERROR(NS_BASE_STREAM_WOULD_BLOCK,     FAILURE(7)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 3: NS_ERROR_MODULE_GFX */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_GFX
+  /* no printer available (e.g. cannot find _any_ printer) */
+  ERROR(NS_ERROR_GFX_PRINTER_NO_PRINTER_AVAILABLE,        FAILURE(1)),
+  /* _specified_ (by name) printer not found */
+  ERROR(NS_ERROR_GFX_PRINTER_NAME_NOT_FOUND,              FAILURE(2)),
+  /* print-to-file: could not open output file */
+  ERROR(NS_ERROR_GFX_PRINTER_COULD_NOT_OPEN_FILE,         FAILURE(3)),
+  /* print: starting document */
+  ERROR(NS_ERROR_GFX_PRINTER_STARTDOC,                    FAILURE(4)),
+  /* print: ending document */
+  ERROR(NS_ERROR_GFX_PRINTER_ENDDOC,                      FAILURE(5)),
+  /* print: starting page */
+  ERROR(NS_ERROR_GFX_PRINTER_STARTPAGE,                   FAILURE(6)),
+  /* The document is still being loaded */
+  ERROR(NS_ERROR_GFX_PRINTER_DOC_IS_BUSY,                 FAILURE(7)),
+
+  /* Font cmap is strangely structured - avoid this font! */
+  ERROR(NS_ERROR_GFX_CMAP_MALFORMED,                      FAILURE(51)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 4:  NS_ERROR_MODULE_WIDGET */
+  /* ======================================================================= */
+#define MODULE  NS_ERROR_MODULE_WIDGET
+  /* Used by:
+   *   - nsIWidget::NotifyIME()
+   *   - nsIWidget::OnWindowedPluginKeyEvent()
+   * Returned when the notification or the event is handled and it's consumed
+   * by somebody. */
+  ERROR(NS_SUCCESS_EVENT_CONSUMED,                        SUCCESS(1)),
+  /* Used by:
+   *   - nsIWidget::OnWindowedPluginKeyEvent()
+   * Returned when the event is handled correctly but the result will be
+   * notified asynchronously. */
+  ERROR(NS_SUCCESS_EVENT_HANDLED_ASYNCHRONOUSLY,          SUCCESS(2)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 6: NS_ERROR_MODULE_NETWORK */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_NETWORK
+  /* General async request error codes:
+   *
+   * These error codes are commonly passed through callback methods to indicate
+   * the status of some requested async request.
+   *
+   * For example, see nsIRequestObserver::onStopRequest.
+   */
+
+  /* The async request completed successfully. */
+  ERROR(NS_BINDING_SUCCEEDED,  NS_OK),
+
+  /* The async request failed for some unknown reason.  */
+  ERROR(NS_BINDING_FAILED,      FAILURE(1)),
+  /* The async request failed because it was aborted by some user action. */
+  ERROR(NS_BINDING_ABORTED,     FAILURE(2)),
+  /* The async request has been "redirected" to a different async request.
+   * (e.g., an HTTP redirect occurred).
+   *
+   * This error code is used with load groups to notify the load group observer
+   * when a request in the load group is redirected to another request. */
+  ERROR(NS_BINDING_REDIRECTED,  FAILURE(3)),
+  /* The async request has been "retargeted" to a different "handler."
+   *
+   * This error code is used with load groups to notify the load group observer
+   * when a request in the load group is removed from the load group and added
+   * to a different load group. */
+  ERROR(NS_BINDING_RETARGETED,  FAILURE(4)),
+
+  /* Miscellaneous error codes: These errors are not typically passed via
+   * onStopRequest. */
+
+  /* The URI is malformed. */
+  ERROR(NS_ERROR_MALFORMED_URI,                       FAILURE(10)),
+  /* The requested action could not be completed while the object is busy.
+   * Implementations of nsIChannel::asyncOpen will commonly return this error
+   * if the channel has already been opened (and has not yet been closed). */
+  ERROR(NS_ERROR_IN_PROGRESS,                         FAILURE(15)),
+  /* Returned from nsIChannel::asyncOpen to indicate that OnDataAvailable will
+   * not be called because there is no content available.  This is used by
+   * helper app style protocols (e.g., mailto).  XXX perhaps this should be a
+   * success code. */
+  ERROR(NS_ERROR_NO_CONTENT,                          FAILURE(17)),
+  /* The URI scheme corresponds to an unknown protocol handler. */
+  ERROR(NS_ERROR_UNKNOWN_PROTOCOL,                    FAILURE(18)),
+  /* The content encoding of the source document was incorrect, for example
+   * returning a plain HTML document advertised as Content-Encoding: gzip */
+  ERROR(NS_ERROR_INVALID_CONTENT_ENCODING,            FAILURE(27)),
+  /* A transport level corruption was found in the source document. for example
+   * a document with a calculated checksum that does not match the Content-MD5
+   * http header. */
+  ERROR(NS_ERROR_CORRUPTED_CONTENT,                   FAILURE(29)),
+  /* A content signature verification failed for some reason. This can be either
+   * an actual verification error, or any other error that led to the fact that
+   * a content signature that was expected couldn't be verified. */
+  ERROR(NS_ERROR_INVALID_SIGNATURE,                   FAILURE(58)),
+  /* While parsing for the first component of a header field using syntax as in
+   * Content-Disposition or Content-Type, the first component was found to be
+   * empty, such as in: Content-Disposition: ; filename=foo */
+  ERROR(NS_ERROR_FIRST_HEADER_FIELD_COMPONENT_EMPTY,  FAILURE(34)),
+  /* Returned from nsIChannel::asyncOpen when trying to open the channel again
+   * (reopening is not supported). */
+  ERROR(NS_ERROR_ALREADY_OPENED,                      FAILURE(73)),
+
+  /* Connectivity error codes: */
+
+  /* The connection is already established.  XXX unused - consider removing. */
+  ERROR(NS_ERROR_ALREADY_CONNECTED,         FAILURE(11)),
+  /* The connection does not exist.  XXX unused - consider removing. */
+  ERROR(NS_ERROR_NOT_CONNECTED,             FAILURE(12)),
+  /* The connection attempt failed, for example, because no server was
+   * listening at specified host:port. */
+  ERROR(NS_ERROR_CONNECTION_REFUSED,        FAILURE(13)),
+  /* The connection was lost due to a timeout error.  */
+  ERROR(NS_ERROR_NET_TIMEOUT,               FAILURE(14)),
+  /* The requested action could not be completed while the networking library
+   * is in the offline state. */
+  ERROR(NS_ERROR_OFFLINE,                   FAILURE(16)),
+  /* The requested action was prohibited because it would have caused the
+   * networking library to establish a connection to an unsafe or otherwise
+   * banned port. */
+  ERROR(NS_ERROR_PORT_ACCESS_NOT_ALLOWED,   FAILURE(19)),
+  /* The connection was established, but no data was ever received. */
+  ERROR(NS_ERROR_NET_RESET,                 FAILURE(20)),
+  /* The connection was established, but the data transfer was interrupted. */
+  ERROR(NS_ERROR_NET_INTERRUPT,             FAILURE(71)),
+  /* The connection attempt to a proxy failed. */
+  ERROR(NS_ERROR_PROXY_CONNECTION_REFUSED,  FAILURE(72)),
+  /* A transfer was only partially done when it completed. */
+  ERROR(NS_ERROR_NET_PARTIAL_TRANSFER,      FAILURE(76)),
+  /* HTTP/2 detected invalid TLS configuration */
+  ERROR(NS_ERROR_NET_INADEQUATE_SECURITY,   FAILURE(82)),
+
+  /* XXX really need to better rationalize these error codes.  are consumers of
+   * necko really expected to know how to discern the meaning of these?? */
+  /* This request is not resumable, but it was tried to resume it, or to
+   * request resume-specific data. */
+  ERROR(NS_ERROR_NOT_RESUMABLE,        FAILURE(25)),
+  /* The request failed as a result of a detected redirection loop.  */
+  ERROR(NS_ERROR_REDIRECT_LOOP,        FAILURE(31)),
+  /* It was attempted to resume the request, but the entity has changed in the
+   * meantime. */
+  ERROR(NS_ERROR_ENTITY_CHANGED,       FAILURE(32)),
+  /* The request failed because the content type returned by the server was not
+   * a type expected by the channel (for nested channels such as the JAR
+   * channel). */
+  ERROR(NS_ERROR_UNSAFE_CONTENT_TYPE,  FAILURE(74)),
+  /* The request failed because the user tried to access to a remote XUL
+   * document from a website that is not in its white-list. */
+  ERROR(NS_ERROR_REMOTE_XUL,           FAILURE(75)),
+  /* The request resulted in an error page being displayed. */
+  ERROR(NS_ERROR_LOAD_SHOWED_ERRORPAGE, FAILURE(77)),
+
+
+  /* FTP specific error codes: */
+
+  ERROR(NS_ERROR_FTP_LOGIN,  FAILURE(21)),
+  ERROR(NS_ERROR_FTP_CWD,    FAILURE(22)),
+  ERROR(NS_ERROR_FTP_PASV,   FAILURE(23)),
+  ERROR(NS_ERROR_FTP_PWD,    FAILURE(24)),
+  ERROR(NS_ERROR_FTP_LIST,   FAILURE(28)),
+
+  /* DNS specific error codes: */
+
+  /* The lookup of a hostname failed.  This generally refers to the hostname
+   * from the URL being loaded. */
+  ERROR(NS_ERROR_UNKNOWN_HOST,           FAILURE(30)),
+  /* A low or medium priority DNS lookup failed because the pending queue was
+   * already full. High priorty (the default) always makes room */
+  ERROR(NS_ERROR_DNS_LOOKUP_QUEUE_FULL,  FAILURE(33)),
+  /* The lookup of a proxy hostname failed.  If a channel is configured to
+   * speak to a proxy server, then it will generate this error if the proxy
+   * hostname cannot be resolved. */
+  ERROR(NS_ERROR_UNKNOWN_PROXY_HOST,     FAILURE(42)),
+
+
+  /* Socket specific error codes: */
+
+  /* The specified socket type does not exist. */
+  ERROR(NS_ERROR_UNKNOWN_SOCKET_TYPE,   FAILURE(51)),
+  /* The specified socket type could not be created. */
+  ERROR(NS_ERROR_SOCKET_CREATE_FAILED,  FAILURE(52)),
+  /* The operating system doesn't support the given type of address. */
+  ERROR(NS_ERROR_SOCKET_ADDRESS_NOT_SUPPORTED, FAILURE(53)),
+  /* The address to which we tried to bind the socket was busy. */
+  ERROR(NS_ERROR_SOCKET_ADDRESS_IN_USE, FAILURE(54)),
+
+  /* Cache specific error codes: */
+  ERROR(NS_ERROR_CACHE_KEY_NOT_FOUND,        FAILURE(61)),
+  ERROR(NS_ERROR_CACHE_DATA_IS_STREAM,       FAILURE(62)),
+  ERROR(NS_ERROR_CACHE_DATA_IS_NOT_STREAM,   FAILURE(63)),
+  ERROR(NS_ERROR_CACHE_WAIT_FOR_VALIDATION,  FAILURE(64)),
+  ERROR(NS_ERROR_CACHE_ENTRY_DOOMED,         FAILURE(65)),
+  ERROR(NS_ERROR_CACHE_READ_ACCESS_DENIED,   FAILURE(66)),
+  ERROR(NS_ERROR_CACHE_WRITE_ACCESS_DENIED,  FAILURE(67)),
+  ERROR(NS_ERROR_CACHE_IN_USE,               FAILURE(68)),
+  /* Error passed through onStopRequest if the document could not be fetched
+   * from the cache. */
+  ERROR(NS_ERROR_DOCUMENT_NOT_CACHED,        FAILURE(70)),
+
+  /* Effective TLD Service specific error codes: */
+
+  /* The requested number of domain levels exceeds those present in the host
+   * string. */
+  ERROR(NS_ERROR_INSUFFICIENT_DOMAIN_LEVELS,  FAILURE(80)),
+  /* The host string is an IP address. */
+  ERROR(NS_ERROR_HOST_IS_IP_ADDRESS,          FAILURE(81)),
+
+
+  /* StreamLoader specific result codes: */
+
+  /* Result code returned by nsIStreamLoaderObserver to indicate that the
+   * observer is taking over responsibility for the data buffer, and the loader
+   * should NOT free it. */
+  ERROR(NS_SUCCESS_ADOPTED_DATA,  SUCCESS(90)),
+
+  /* FTP */
+  ERROR(NS_NET_STATUS_BEGIN_FTP_TRANSACTION,  SUCCESS(27)),
+  ERROR(NS_NET_STATUS_END_FTP_TRANSACTION,    SUCCESS(28)),
+
+  /* This success code may be returned by nsIAuthModule::getNextToken to
+   * indicate that the authentication is finished and thus there's no need
+   * to call getNextToken again. */
+  ERROR(NS_SUCCESS_AUTH_FINISHED,  SUCCESS(40)),
+
+  /* These are really not "results", they're statuses, used by nsITransport and
+   * friends.  This is abuse of nsresult, but we'll put up with it for now. */
+  /* nsITransport */
+  ERROR(NS_NET_STATUS_READING,  FAILURE(8)),
+  ERROR(NS_NET_STATUS_WRITING,  FAILURE(9)),
+
+  /* nsISocketTransport */
+  ERROR(NS_NET_STATUS_RESOLVING_HOST,  FAILURE(3)),
+  ERROR(NS_NET_STATUS_RESOLVED_HOST,   FAILURE(11)),
+  ERROR(NS_NET_STATUS_CONNECTING_TO,   FAILURE(7)),
+  ERROR(NS_NET_STATUS_CONNECTED_TO,    FAILURE(4)),
+  ERROR(NS_NET_STATUS_SENDING_TO,      FAILURE(5)),
+  ERROR(NS_NET_STATUS_WAITING_FOR,     FAILURE(10)),
+  ERROR(NS_NET_STATUS_RECEIVING_FROM,  FAILURE(6)),
+
+  /* nsIInterceptedChannel */
+  /* Generic error for non-specific failures during service worker interception */
+  ERROR(NS_ERROR_INTERCEPTION_FAILED,                  FAILURE(100)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 7: NS_ERROR_MODULE_PLUGINS */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_PLUGINS
+  ERROR(NS_ERROR_PLUGINS_PLUGINSNOTCHANGED,        FAILURE(1000)),
+  ERROR(NS_ERROR_PLUGIN_DISABLED,                  FAILURE(1001)),
+  ERROR(NS_ERROR_PLUGIN_BLOCKLISTED,               FAILURE(1002)),
+  ERROR(NS_ERROR_PLUGIN_TIME_RANGE_NOT_SUPPORTED,  FAILURE(1003)),
+  ERROR(NS_ERROR_PLUGIN_CLICKTOPLAY,               FAILURE(1004)),
+  ERROR(NS_PLUGIN_INIT_PENDING,                    SUCCESS(1005)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 8: NS_ERROR_MODULE_LAYOUT */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_LAYOUT
+  /* Return code for nsITableLayout */
+  ERROR(NS_TABLELAYOUT_CELL_NOT_FOUND,  SUCCESS(0)),
+  /* Return code for nsFrame::GetNextPrevLineFromeBlockFrame */
+  ERROR(NS_POSITION_BEFORE_TABLE,       SUCCESS(3)),
+  /** Return codes for nsPresState::GetProperty() */
+  /* Returned if the property exists */
+  ERROR(NS_STATE_PROPERTY_EXISTS,       NS_OK),
+  /* Returned if the property does not exist */
+  ERROR(NS_STATE_PROPERTY_NOT_THERE,    SUCCESS(5)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 9: NS_ERROR_MODULE_HTMLPARSER */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_HTMLPARSER
+  ERROR(NS_ERROR_HTMLPARSER_CONTINUE,  NS_OK),
+
+  ERROR(NS_ERROR_HTMLPARSER_EOF,                        FAILURE(1000)),
+  ERROR(NS_ERROR_HTMLPARSER_UNKNOWN,                    FAILURE(1001)),
+  ERROR(NS_ERROR_HTMLPARSER_CANTPROPAGATE,              FAILURE(1002)),
+  ERROR(NS_ERROR_HTMLPARSER_CONTEXTMISMATCH,            FAILURE(1003)),
+  ERROR(NS_ERROR_HTMLPARSER_BADFILENAME,                FAILURE(1004)),
+  ERROR(NS_ERROR_HTMLPARSER_BADURL,                     FAILURE(1005)),
+  ERROR(NS_ERROR_HTMLPARSER_INVALIDPARSERCONTEXT,       FAILURE(1006)),
+  ERROR(NS_ERROR_HTMLPARSER_INTERRUPTED,                FAILURE(1007)),
+  ERROR(NS_ERROR_HTMLPARSER_BLOCK,                      FAILURE(1008)),
+  ERROR(NS_ERROR_HTMLPARSER_BADTOKENIZER,               FAILURE(1009)),
+  ERROR(NS_ERROR_HTMLPARSER_BADATTRIBUTE,               FAILURE(1010)),
+  ERROR(NS_ERROR_HTMLPARSER_UNRESOLVEDDTD,              FAILURE(1011)),
+  ERROR(NS_ERROR_HTMLPARSER_MISPLACEDTABLECONTENT,      FAILURE(1012)),
+  ERROR(NS_ERROR_HTMLPARSER_BADDTD,                     FAILURE(1013)),
+  ERROR(NS_ERROR_HTMLPARSER_BADCONTEXT,                 FAILURE(1014)),
+  ERROR(NS_ERROR_HTMLPARSER_STOPPARSING,                FAILURE(1015)),
+  ERROR(NS_ERROR_HTMLPARSER_UNTERMINATEDSTRINGLITERAL,  FAILURE(1016)),
+  ERROR(NS_ERROR_HTMLPARSER_HIERARCHYTOODEEP,           FAILURE(1017)),
+  ERROR(NS_ERROR_HTMLPARSER_FAKE_ENDTAG,                FAILURE(1018)),
+  ERROR(NS_ERROR_HTMLPARSER_INVALID_COMMENT,            FAILURE(1019)),
+
+  ERROR(NS_HTMLTOKENS_NOT_AN_ENTITY,       SUCCESS(2000)),
+  ERROR(NS_HTMLPARSER_VALID_META_CHARSET,  SUCCESS(3000)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 10: NS_ERROR_MODULE_RDF */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_RDF
+  /* Returned from nsIRDFDataSource::Assert() and Unassert() if the assertion
+   * (or unassertion was accepted by the datasource */
+  ERROR(NS_RDF_ASSERTION_ACCEPTED,  NS_OK),
+  /* Returned from nsIRDFCursor::Advance() if the cursor has no more
+   * elements to enumerate */
+  ERROR(NS_RDF_CURSOR_EMPTY,        SUCCESS(1)),
+  /* Returned from nsIRDFDataSource::GetSource() and GetTarget() if the
+   * source/target has no value */
+  ERROR(NS_RDF_NO_VALUE,            SUCCESS(2)),
+  /* Returned from nsIRDFDataSource::Assert() and Unassert() if the assertion
+   * (or unassertion) was rejected by the datasource; i.e., the datasource was
+   * not willing to record the statement. */
+  ERROR(NS_RDF_ASSERTION_REJECTED,  SUCCESS(3)),
+  /* Return this from rdfITripleVisitor to stop cycling */
+  ERROR(NS_RDF_STOP_VISIT,          SUCCESS(4)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 11: NS_ERROR_MODULE_UCONV */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_UCONV
+  ERROR(NS_ERROR_UCONV_NOCONV,       FAILURE(1)),
+  ERROR(NS_ERROR_UDEC_ILLEGALINPUT,  FAILURE(14)),
+
+  ERROR(NS_SUCCESS_USING_FALLBACK_LOCALE,  SUCCESS(2)),
+  ERROR(NS_OK_UDEC_EXACTLENGTH,            SUCCESS(11)),
+  ERROR(NS_OK_UDEC_MOREINPUT,              SUCCESS(12)),
+  ERROR(NS_OK_UDEC_MOREOUTPUT,             SUCCESS(13)),
+  ERROR(NS_OK_UDEC_NOBOMFOUND,             SUCCESS(14)),
+  ERROR(NS_OK_UENC_EXACTLENGTH,            SUCCESS(33)),
+  ERROR(NS_OK_UENC_MOREOUTPUT,             SUCCESS(34)),
+  ERROR(NS_ERROR_UENC_NOMAPPING,           SUCCESS(35)),
+  ERROR(NS_OK_UENC_MOREINPUT,              SUCCESS(36)),
+
+  /* BEGIN DEPRECATED */
+  ERROR(NS_EXACT_LENGTH,         NS_OK_UDEC_EXACTLENGTH),
+  ERROR(NS_PARTIAL_MORE_INPUT,   NS_OK_UDEC_MOREINPUT),
+  ERROR(NS_PARTIAL_MORE_OUTPUT,  NS_OK_UDEC_MOREOUTPUT),
+  ERROR(NS_ERROR_ILLEGAL_INPUT,  NS_ERROR_UDEC_ILLEGALINPUT),
+  /* END DEPRECATED */
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 13: NS_ERROR_MODULE_FILES */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_FILES
+  ERROR(NS_ERROR_FILE_UNRECOGNIZED_PATH,      FAILURE(1)),
+  ERROR(NS_ERROR_FILE_UNRESOLVABLE_SYMLINK,   FAILURE(2)),
+  ERROR(NS_ERROR_FILE_EXECUTION_FAILED,       FAILURE(3)),
+  ERROR(NS_ERROR_FILE_UNKNOWN_TYPE,           FAILURE(4)),
+  ERROR(NS_ERROR_FILE_DESTINATION_NOT_DIR,    FAILURE(5)),
+  ERROR(NS_ERROR_FILE_TARGET_DOES_NOT_EXIST,  FAILURE(6)),
+  ERROR(NS_ERROR_FILE_COPY_OR_MOVE_FAILED,    FAILURE(7)),
+  ERROR(NS_ERROR_FILE_ALREADY_EXISTS,         FAILURE(8)),
+  ERROR(NS_ERROR_FILE_INVALID_PATH,           FAILURE(9)),
+  ERROR(NS_ERROR_FILE_DISK_FULL,              FAILURE(10)),
+  ERROR(NS_ERROR_FILE_CORRUPTED,              FAILURE(11)),
+  ERROR(NS_ERROR_FILE_NOT_DIRECTORY,          FAILURE(12)),
+  ERROR(NS_ERROR_FILE_IS_DIRECTORY,           FAILURE(13)),
+  ERROR(NS_ERROR_FILE_IS_LOCKED,              FAILURE(14)),
+  ERROR(NS_ERROR_FILE_TOO_BIG,                FAILURE(15)),
+  ERROR(NS_ERROR_FILE_NO_DEVICE_SPACE,        FAILURE(16)),
+  ERROR(NS_ERROR_FILE_NAME_TOO_LONG,          FAILURE(17)),
+  ERROR(NS_ERROR_FILE_NOT_FOUND,              FAILURE(18)),
+  ERROR(NS_ERROR_FILE_READ_ONLY,              FAILURE(19)),
+  ERROR(NS_ERROR_FILE_DIR_NOT_EMPTY,          FAILURE(20)),
+  ERROR(NS_ERROR_FILE_ACCESS_DENIED,          FAILURE(21)),
+
+  ERROR(NS_SUCCESS_FILE_DIRECTORY_EMPTY,  SUCCESS(1)),
+  /* Result codes used by nsIDirectoryServiceProvider2 */
+  ERROR(NS_SUCCESS_AGGREGATE_RESULT,      SUCCESS(2)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 14: NS_ERROR_MODULE_DOM */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_DOM
+  /* XXX If you add a new DOM error code, also add an error string to
+   * dom/base/domerr.msg */
+
+  /* Standard DOM error codes: http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html */
+  ERROR(NS_ERROR_DOM_INDEX_SIZE_ERR,               FAILURE(1)),
+  ERROR(NS_ERROR_DOM_HIERARCHY_REQUEST_ERR,        FAILURE(3)),
+  ERROR(NS_ERROR_DOM_WRONG_DOCUMENT_ERR,           FAILURE(4)),
+  ERROR(NS_ERROR_DOM_INVALID_CHARACTER_ERR,        FAILURE(5)),
+  ERROR(NS_ERROR_DOM_NO_MODIFICATION_ALLOWED_ERR,  FAILURE(7)),
+  ERROR(NS_ERROR_DOM_NOT_FOUND_ERR,                FAILURE(8)),
+  ERROR(NS_ERROR_DOM_NOT_SUPPORTED_ERR,            FAILURE(9)),
+  ERROR(NS_ERROR_DOM_INUSE_ATTRIBUTE_ERR,          FAILURE(10)),
+  ERROR(NS_ERROR_DOM_INVALID_STATE_ERR,            FAILURE(11)),
+  ERROR(NS_ERROR_DOM_SYNTAX_ERR,                   FAILURE(12)),
+  ERROR(NS_ERROR_DOM_INVALID_MODIFICATION_ERR,     FAILURE(13)),
+  ERROR(NS_ERROR_DOM_NAMESPACE_ERR,                FAILURE(14)),
+  ERROR(NS_ERROR_DOM_INVALID_ACCESS_ERR,           FAILURE(15)),
+  ERROR(NS_ERROR_DOM_TYPE_MISMATCH_ERR,            FAILURE(17)),
+  ERROR(NS_ERROR_DOM_SECURITY_ERR,                 FAILURE(18)),
+  ERROR(NS_ERROR_DOM_NETWORK_ERR,                  FAILURE(19)),
+  ERROR(NS_ERROR_DOM_ABORT_ERR,                    FAILURE(20)),
+  ERROR(NS_ERROR_DOM_URL_MISMATCH_ERR,             FAILURE(21)),
+  ERROR(NS_ERROR_DOM_QUOTA_EXCEEDED_ERR,           FAILURE(22)),
+  ERROR(NS_ERROR_DOM_TIMEOUT_ERR,                  FAILURE(23)),
+  ERROR(NS_ERROR_DOM_INVALID_NODE_TYPE_ERR,        FAILURE(24)),
+  ERROR(NS_ERROR_DOM_DATA_CLONE_ERR,               FAILURE(25)),
+  /* XXX Should be JavaScript native errors */
+  ERROR(NS_ERROR_TYPE_ERR,                         FAILURE(26)),
+  ERROR(NS_ERROR_RANGE_ERR,                        FAILURE(27)),
+  /* StringEncoding API errors from http://wiki.whatwg.org/wiki/StringEncoding */
+  ERROR(NS_ERROR_DOM_ENCODING_NOT_SUPPORTED_ERR,   FAILURE(28)),
+  ERROR(NS_ERROR_DOM_INVALID_POINTER_ERR,          FAILURE(29)),
+  /* WebCrypto API errors from http://www.w3.org/TR/WebCryptoAPI/ */
+  ERROR(NS_ERROR_DOM_UNKNOWN_ERR,                  FAILURE(30)),
+  ERROR(NS_ERROR_DOM_DATA_ERR,                     FAILURE(31)),
+  ERROR(NS_ERROR_DOM_OPERATION_ERR,                FAILURE(32)),
+  /* https://heycam.github.io/webidl/#notallowederror */
+  ERROR(NS_ERROR_DOM_NOT_ALLOWED_ERR,              FAILURE(33)),
+  /* DOM error codes defined by us */
+  ERROR(NS_ERROR_DOM_SECMAN_ERR,                   FAILURE(1001)),
+  ERROR(NS_ERROR_DOM_WRONG_TYPE_ERR,               FAILURE(1002)),
+  ERROR(NS_ERROR_DOM_NOT_OBJECT_ERR,               FAILURE(1003)),
+  ERROR(NS_ERROR_DOM_NOT_XPC_OBJECT_ERR,           FAILURE(1004)),
+  ERROR(NS_ERROR_DOM_NOT_NUMBER_ERR,               FAILURE(1005)),
+  ERROR(NS_ERROR_DOM_NOT_BOOLEAN_ERR,              FAILURE(1006)),
+  ERROR(NS_ERROR_DOM_NOT_FUNCTION_ERR,             FAILURE(1007)),
+  ERROR(NS_ERROR_DOM_TOO_FEW_PARAMETERS_ERR,       FAILURE(1008)),
+  ERROR(NS_ERROR_DOM_BAD_DOCUMENT_DOMAIN,          FAILURE(1009)),
+  ERROR(NS_ERROR_DOM_PROP_ACCESS_DENIED,           FAILURE(1010)),
+  ERROR(NS_ERROR_DOM_XPCONNECT_ACCESS_DENIED,      FAILURE(1011)),
+  ERROR(NS_ERROR_DOM_BAD_URI,                      FAILURE(1012)),
+  ERROR(NS_ERROR_DOM_RETVAL_UNDEFINED,             FAILURE(1013)),
+  ERROR(NS_ERROR_DOM_QUOTA_REACHED,                FAILURE(1014)),
+  ERROR(NS_ERROR_DOM_JS_EXCEPTION,                 FAILURE(1015)),
+
+  /* A way to represent uncatchable exceptions */
+  ERROR(NS_ERROR_UNCATCHABLE_EXCEPTION,            FAILURE(1016)),
+
+  /* An nsresult value to use in ErrorResult to indicate that we want to throw
+     a DOMException */
+  ERROR(NS_ERROR_DOM_DOMEXCEPTION,                 FAILURE(1017)),
+
+  /* An nsresult value to use in ErrorResult to indicate that we
+   * should just rethrow whatever is on the JSContext (which might be
+   * nothing if an uncatchable exception was thrown).
+   */
+  ERROR(NS_ERROR_DOM_EXCEPTION_ON_JSCONTEXT,       FAILURE(1018)),
+
+  ERROR(NS_ERROR_DOM_MALFORMED_URI,                FAILURE(1019)),
+  ERROR(NS_ERROR_DOM_INVALID_HEADER_NAME,          FAILURE(1020)),
+
+  ERROR(NS_ERROR_DOM_INVALID_STATE_XHR_HAS_INVALID_CONTEXT,                            FAILURE(1021)),
+  ERROR(NS_ERROR_DOM_INVALID_STATE_XHR_MUST_BE_OPENED,                                 FAILURE(1022)),
+  ERROR(NS_ERROR_DOM_INVALID_STATE_XHR_MUST_NOT_BE_SENDING,                            FAILURE(1023)),
+  ERROR(NS_ERROR_DOM_INVALID_STATE_XHR_MUST_NOT_BE_LOADING_OR_DONE,                    FAILURE(1024)),
+  ERROR(NS_ERROR_DOM_INVALID_STATE_XHR_HAS_WRONG_RESPONSETYPE_FOR_RESPONSEXML,         FAILURE(1025)),
+  ERROR(NS_ERROR_DOM_INVALID_STATE_XHR_HAS_WRONG_RESPONSETYPE_FOR_RESPONSETEXT,        FAILURE(1026)),
+  ERROR(NS_ERROR_DOM_INVALID_STATE_XHR_CHUNKED_RESPONSETYPES_UNSUPPORTED_FOR_SYNC,     FAILURE(1027)),
+  ERROR(NS_ERROR_DOM_INVALID_ACCESS_XHR_TIMEOUT_AND_RESPONSETYPE_UNSUPPORTED_FOR_SYNC, FAILURE(1028)),
+
+  /* May be used to indicate when e.g. setting a property value didn't
+   * actually change the value, like for obj.foo = "bar"; obj.foo = "bar";
+   * the second assignment throws NS_SUCCESS_DOM_NO_OPERATION.
+   */
+  ERROR(NS_SUCCESS_DOM_NO_OPERATION,               SUCCESS(1)),
+
+  /*
+   * A success code that indicates that evaluating a string of JS went
+   * just fine except it threw an exception. Only for legacy use by
+   * nsJSUtils.
+   */
+  ERROR(NS_SUCCESS_DOM_SCRIPT_EVALUATION_THREW,    SUCCESS(2)),
+
+  /*
+   * A success code that indicates that evaluating a string of JS went
+   * just fine except it was killed by an uncatchable exception.
+   * Only for legacy use by nsJSUtils.
+   */
+  ERROR(NS_SUCCESS_DOM_SCRIPT_EVALUATION_THREW_UNCATCHABLE, SUCCESS(3)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 15: NS_ERROR_MODULE_IMGLIB */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_IMGLIB
+  ERROR(NS_IMAGELIB_SUCCESS_LOAD_FINISHED,  SUCCESS(0)),
+  ERROR(NS_IMAGELIB_CHANGING_OWNER,         SUCCESS(1)),
+
+  ERROR(NS_IMAGELIB_ERROR_FAILURE,       FAILURE(5)),
+  ERROR(NS_IMAGELIB_ERROR_NO_DECODER,    FAILURE(6)),
+  ERROR(NS_IMAGELIB_ERROR_NOT_FINISHED,  FAILURE(7)),
+  ERROR(NS_IMAGELIB_ERROR_NO_ENCODER,    FAILURE(9)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 17: NS_ERROR_MODULE_EDITOR */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_EDITOR
+  ERROR(NS_SUCCESS_EDITOR_ELEMENT_NOT_FOUND,   SUCCESS(1)),
+  ERROR(NS_SUCCESS_EDITOR_FOUND_TARGET,        SUCCESS(2)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 18: NS_ERROR_MODULE_XPCONNECT */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_XPCONNECT
+  ERROR(NS_ERROR_XPC_NOT_ENOUGH_ARGS,                  FAILURE(1)),
+  ERROR(NS_ERROR_XPC_NEED_OUT_OBJECT,                  FAILURE(2)),
+  ERROR(NS_ERROR_XPC_CANT_SET_OUT_VAL,                 FAILURE(3)),
+  ERROR(NS_ERROR_XPC_NATIVE_RETURNED_FAILURE,          FAILURE(4)),
+  ERROR(NS_ERROR_XPC_CANT_GET_INTERFACE_INFO,          FAILURE(5)),
+  ERROR(NS_ERROR_XPC_CANT_GET_PARAM_IFACE_INFO,        FAILURE(6)),
+  ERROR(NS_ERROR_XPC_CANT_GET_METHOD_INFO,             FAILURE(7)),
+  ERROR(NS_ERROR_XPC_UNEXPECTED,                       FAILURE(8)),
+  ERROR(NS_ERROR_XPC_BAD_CONVERT_JS,                   FAILURE(9)),
+  ERROR(NS_ERROR_XPC_BAD_CONVERT_NATIVE,               FAILURE(10)),
+  ERROR(NS_ERROR_XPC_BAD_CONVERT_JS_NULL_REF,          FAILURE(11)),
+  ERROR(NS_ERROR_XPC_BAD_OP_ON_WN_PROTO,               FAILURE(12)),
+  ERROR(NS_ERROR_XPC_CANT_CONVERT_WN_TO_FUN,           FAILURE(13)),
+  ERROR(NS_ERROR_XPC_CANT_DEFINE_PROP_ON_WN,           FAILURE(14)),
+  ERROR(NS_ERROR_XPC_CANT_WATCH_WN_STATIC,             FAILURE(15)),
+  ERROR(NS_ERROR_XPC_CANT_EXPORT_WN_STATIC,            FAILURE(16)),
+  ERROR(NS_ERROR_XPC_SCRIPTABLE_CALL_FAILED,           FAILURE(17)),
+  ERROR(NS_ERROR_XPC_SCRIPTABLE_CTOR_FAILED,           FAILURE(18)),
+  ERROR(NS_ERROR_XPC_CANT_CALL_WO_SCRIPTABLE,          FAILURE(19)),
+  ERROR(NS_ERROR_XPC_CANT_CTOR_WO_SCRIPTABLE,          FAILURE(20)),
+  ERROR(NS_ERROR_XPC_CI_RETURNED_FAILURE,              FAILURE(21)),
+  ERROR(NS_ERROR_XPC_GS_RETURNED_FAILURE,              FAILURE(22)),
+  ERROR(NS_ERROR_XPC_BAD_CID,                          FAILURE(23)),
+  ERROR(NS_ERROR_XPC_BAD_IID,                          FAILURE(24)),
+  ERROR(NS_ERROR_XPC_CANT_CREATE_WN,                   FAILURE(25)),
+  ERROR(NS_ERROR_XPC_JS_THREW_EXCEPTION,               FAILURE(26)),
+  ERROR(NS_ERROR_XPC_JS_THREW_NATIVE_OBJECT,           FAILURE(27)),
+  ERROR(NS_ERROR_XPC_JS_THREW_JS_OBJECT,               FAILURE(28)),
+  ERROR(NS_ERROR_XPC_JS_THREW_NULL,                    FAILURE(29)),
+  ERROR(NS_ERROR_XPC_JS_THREW_STRING,                  FAILURE(30)),
+  ERROR(NS_ERROR_XPC_JS_THREW_NUMBER,                  FAILURE(31)),
+  ERROR(NS_ERROR_XPC_JAVASCRIPT_ERROR,                 FAILURE(32)),
+  ERROR(NS_ERROR_XPC_JAVASCRIPT_ERROR_WITH_DETAILS,    FAILURE(33)),
+  ERROR(NS_ERROR_XPC_CANT_CONVERT_PRIMITIVE_TO_ARRAY,  FAILURE(34)),
+  ERROR(NS_ERROR_XPC_CANT_CONVERT_OBJECT_TO_ARRAY,     FAILURE(35)),
+  ERROR(NS_ERROR_XPC_NOT_ENOUGH_ELEMENTS_IN_ARRAY,     FAILURE(36)),
+  ERROR(NS_ERROR_XPC_CANT_GET_ARRAY_INFO,              FAILURE(37)),
+  ERROR(NS_ERROR_XPC_NOT_ENOUGH_CHARS_IN_STRING,       FAILURE(38)),
+  ERROR(NS_ERROR_XPC_SECURITY_MANAGER_VETO,            FAILURE(39)),
+  ERROR(NS_ERROR_XPC_INTERFACE_NOT_SCRIPTABLE,         FAILURE(40)),
+  ERROR(NS_ERROR_XPC_INTERFACE_NOT_FROM_NSISUPPORTS,   FAILURE(41)),
+  ERROR(NS_ERROR_XPC_CANT_GET_JSOBJECT_OF_DOM_OBJECT,  FAILURE(42)),
+  ERROR(NS_ERROR_XPC_CANT_SET_READ_ONLY_CONSTANT,      FAILURE(43)),
+  ERROR(NS_ERROR_XPC_CANT_SET_READ_ONLY_ATTRIBUTE,     FAILURE(44)),
+  ERROR(NS_ERROR_XPC_CANT_SET_READ_ONLY_METHOD,        FAILURE(45)),
+  ERROR(NS_ERROR_XPC_CANT_ADD_PROP_TO_WRAPPED_NATIVE,  FAILURE(46)),
+  ERROR(NS_ERROR_XPC_CALL_TO_SCRIPTABLE_FAILED,        FAILURE(47)),
+  ERROR(NS_ERROR_XPC_JSOBJECT_HAS_NO_FUNCTION_NAMED,   FAILURE(48)),
+  ERROR(NS_ERROR_XPC_BAD_ID_STRING,                    FAILURE(49)),
+  ERROR(NS_ERROR_XPC_BAD_INITIALIZER_NAME,             FAILURE(50)),
+  ERROR(NS_ERROR_XPC_HAS_BEEN_SHUTDOWN,                FAILURE(51)),
+  ERROR(NS_ERROR_XPC_CANT_MODIFY_PROP_ON_WN,           FAILURE(52)),
+  ERROR(NS_ERROR_XPC_BAD_CONVERT_JS_ZERO_ISNOT_NULL,   FAILURE(53)),
+  ERROR(NS_ERROR_XPC_CANT_PASS_CPOW_TO_NATIVE,         FAILURE(54)),
+  /* any new errors here should have an associated entry added in xpc.msg */
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 19: NS_ERROR_MODULE_PROFILE */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_PROFILE
+  ERROR(NS_ERROR_LAUNCHED_CHILD_PROCESS,  FAILURE(200)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 21: NS_ERROR_MODULE_SECURITY */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_SECURITY
+  /* Error code for CSP */
+  ERROR(NS_ERROR_CSP_FORM_ACTION_VIOLATION,        FAILURE(98)),
+  ERROR(NS_ERROR_CSP_FRAME_ANCESTOR_VIOLATION,     FAILURE(99)),
+
+  /* Error code for Sub-Resource Integrity */
+  ERROR(NS_ERROR_SRI_CORRUPT,                      FAILURE(200)),
+  ERROR(NS_ERROR_SRI_DISABLED,                     FAILURE(201)),
+  ERROR(NS_ERROR_SRI_NOT_ELIGIBLE,                 FAILURE(202)),
+  ERROR(NS_ERROR_SRI_UNEXPECTED_HASH_TYPE,         FAILURE(203)),
+  ERROR(NS_ERROR_SRI_IMPORT,                       FAILURE(204)),
+
+  /* CMS specific nsresult error codes.  Note: the numbers used here correspond
+   * to the values in nsICMSMessageErrors.idl. */
+  ERROR(NS_ERROR_CMS_VERIFY_NOT_SIGNED,            FAILURE(1024)),
+  ERROR(NS_ERROR_CMS_VERIFY_NO_CONTENT_INFO,       FAILURE(1025)),
+  ERROR(NS_ERROR_CMS_VERIFY_BAD_DIGEST,            FAILURE(1026)),
+  ERROR(NS_ERROR_CMS_VERIFY_NOCERT,                FAILURE(1028)),
+  ERROR(NS_ERROR_CMS_VERIFY_UNTRUSTED,             FAILURE(1029)),
+  ERROR(NS_ERROR_CMS_VERIFY_ERROR_UNVERIFIED,      FAILURE(1031)),
+  ERROR(NS_ERROR_CMS_VERIFY_ERROR_PROCESSING,      FAILURE(1032)),
+  ERROR(NS_ERROR_CMS_VERIFY_BAD_SIGNATURE,         FAILURE(1033)),
+  ERROR(NS_ERROR_CMS_VERIFY_DIGEST_MISMATCH,       FAILURE(1034)),
+  ERROR(NS_ERROR_CMS_VERIFY_UNKNOWN_ALGO,          FAILURE(1035)),
+  ERROR(NS_ERROR_CMS_VERIFY_UNSUPPORTED_ALGO,      FAILURE(1036)),
+  ERROR(NS_ERROR_CMS_VERIFY_MALFORMED_SIGNATURE,   FAILURE(1037)),
+  ERROR(NS_ERROR_CMS_VERIFY_HEADER_MISMATCH,       FAILURE(1038)),
+  ERROR(NS_ERROR_CMS_VERIFY_NOT_YET_ATTEMPTED,     FAILURE(1039)),
+  ERROR(NS_ERROR_CMS_VERIFY_CERT_WITHOUT_ADDRESS,  FAILURE(1040)),
+  ERROR(NS_ERROR_CMS_ENCRYPT_NO_BULK_ALG,          FAILURE(1056)),
+  ERROR(NS_ERROR_CMS_ENCRYPT_INCOMPLETE,           FAILURE(1057)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 22: NS_ERROR_MODULE_DOM_XPATH */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_DOM_XPATH
+  /* DOM error codes from http://www.w3.org/TR/DOM-Level-3-XPath/ */
+  ERROR(NS_ERROR_DOM_INVALID_EXPRESSION_ERR,  FAILURE(51)),
+  ERROR(NS_ERROR_DOM_TYPE_ERR,                FAILURE(52)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 24: NS_ERROR_MODULE_URILOADER */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_URILOADER
+  ERROR(NS_ERROR_WONT_HANDLE_CONTENT,   FAILURE(1)),
+  /* The load has been cancelled because it was found on a malware or phishing
+   * blacklist. */
+  ERROR(NS_ERROR_MALWARE_URI,           FAILURE(30)),
+  ERROR(NS_ERROR_PHISHING_URI,          FAILURE(31)),
+  ERROR(NS_ERROR_TRACKING_URI,          FAILURE(34)),
+  ERROR(NS_ERROR_UNWANTED_URI,          FAILURE(35)),
+  ERROR(NS_ERROR_BLOCKED_URI,           FAILURE(37)),
+  /* Used when "Save Link As..." doesn't see the headers quickly enough to
+   * choose a filename.  See nsContextMenu.js. */
+  ERROR(NS_ERROR_SAVE_LINK_AS_TIMEOUT,  FAILURE(32)),
+  /* Used when the data from a channel has already been parsed and cached so it
+   * doesn't need to be reparsed from the original source. */
+  ERROR(NS_ERROR_PARSED_DATA_CACHED,    FAILURE(33)),
+
+  /* This success code indicates that a refresh header was found and
+   * successfully setup.  */
+  ERROR(NS_REFRESHURI_HEADER_FOUND,  SUCCESS(2)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 25: NS_ERROR_MODULE_CONTENT */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_CONTENT
+  /* Error codes for image loading */
+  ERROR(NS_ERROR_IMAGE_SRC_CHANGED,             FAILURE(4)),
+  ERROR(NS_ERROR_IMAGE_BLOCKED,                 FAILURE(5)),
+  /* Error codes for content policy blocking */
+  ERROR(NS_ERROR_CONTENT_BLOCKED,               FAILURE(6)),
+  ERROR(NS_ERROR_CONTENT_BLOCKED_SHOW_ALT,      FAILURE(7)),
+  /* Success variations of content policy blocking */
+  ERROR(NS_PROPTABLE_PROP_NOT_THERE,            FAILURE(10)),
+  /* Error code for XBL */
+  ERROR(NS_ERROR_XBL_BLOCKED,                   FAILURE(15)),
+  /* Error code for when the content process crashed */
+  ERROR(NS_ERROR_CONTENT_CRASHED,               FAILURE(16)),
+
+  /* XXX this is not really used */
+  ERROR(NS_HTML_STYLE_PROPERTY_NOT_THERE,   SUCCESS(2)),
+  ERROR(NS_CONTENT_BLOCKED,                 SUCCESS(8)),
+  ERROR(NS_CONTENT_BLOCKED_SHOW_ALT,        SUCCESS(9)),
+  ERROR(NS_PROPTABLE_PROP_OVERWRITTEN,      SUCCESS(11)),
+  /* Error codes for FindBroadcaster in XULDocument.cpp */
+  ERROR(NS_FINDBROADCASTER_NOT_FOUND,       SUCCESS(12)),
+  ERROR(NS_FINDBROADCASTER_FOUND,           SUCCESS(13)),
+  ERROR(NS_FINDBROADCASTER_AWAIT_OVERLAYS,  SUCCESS(14)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 27: NS_ERROR_MODULE_XSLT */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_XSLT
+  ERROR(NS_ERROR_XPATH_INVALID_ARG,  NS_ERROR_INVALID_ARG),
+
+  ERROR(NS_ERROR_XSLT_PARSE_FAILURE,                  FAILURE(1)),
+  ERROR(NS_ERROR_XPATH_PARSE_FAILURE,                 FAILURE(2)),
+  ERROR(NS_ERROR_XSLT_ALREADY_SET,                    FAILURE(3)),
+  ERROR(NS_ERROR_XSLT_EXECUTION_FAILURE,              FAILURE(4)),
+  ERROR(NS_ERROR_XPATH_UNKNOWN_FUNCTION,              FAILURE(5)),
+  ERROR(NS_ERROR_XSLT_BAD_RECURSION,                  FAILURE(6)),
+  ERROR(NS_ERROR_XSLT_BAD_VALUE,                      FAILURE(7)),
+  ERROR(NS_ERROR_XSLT_NODESET_EXPECTED,               FAILURE(8)),
+  ERROR(NS_ERROR_XSLT_ABORTED,                        FAILURE(9)),
+  ERROR(NS_ERROR_XSLT_NETWORK_ERROR,                  FAILURE(10)),
+  ERROR(NS_ERROR_XSLT_WRONG_MIME_TYPE,                FAILURE(11)),
+  ERROR(NS_ERROR_XSLT_LOAD_RECURSION,                 FAILURE(12)),
+  ERROR(NS_ERROR_XPATH_BAD_ARGUMENT_COUNT,            FAILURE(13)),
+  ERROR(NS_ERROR_XPATH_BAD_EXTENSION_FUNCTION,        FAILURE(14)),
+  ERROR(NS_ERROR_XPATH_PAREN_EXPECTED,                FAILURE(15)),
+  ERROR(NS_ERROR_XPATH_INVALID_AXIS,                  FAILURE(16)),
+  ERROR(NS_ERROR_XPATH_NO_NODE_TYPE_TEST,             FAILURE(17)),
+  ERROR(NS_ERROR_XPATH_BRACKET_EXPECTED,              FAILURE(18)),
+  ERROR(NS_ERROR_XPATH_INVALID_VAR_NAME,              FAILURE(19)),
+  ERROR(NS_ERROR_XPATH_UNEXPECTED_END,                FAILURE(20)),
+  ERROR(NS_ERROR_XPATH_OPERATOR_EXPECTED,             FAILURE(21)),
+  ERROR(NS_ERROR_XPATH_UNCLOSED_LITERAL,              FAILURE(22)),
+  ERROR(NS_ERROR_XPATH_BAD_COLON,                     FAILURE(23)),
+  ERROR(NS_ERROR_XPATH_BAD_BANG,                      FAILURE(24)),
+  ERROR(NS_ERROR_XPATH_ILLEGAL_CHAR,                  FAILURE(25)),
+  ERROR(NS_ERROR_XPATH_BINARY_EXPECTED,               FAILURE(26)),
+  ERROR(NS_ERROR_XSLT_LOAD_BLOCKED_ERROR,             FAILURE(27)),
+  ERROR(NS_ERROR_XPATH_INVALID_EXPRESSION_EVALUATED,  FAILURE(28)),
+  ERROR(NS_ERROR_XPATH_UNBALANCED_CURLY_BRACE,        FAILURE(29)),
+  ERROR(NS_ERROR_XSLT_BAD_NODE_NAME,                  FAILURE(30)),
+  ERROR(NS_ERROR_XSLT_VAR_ALREADY_SET,                FAILURE(31)),
+  ERROR(NS_ERROR_XSLT_CALL_TO_KEY_NOT_ALLOWED,        FAILURE(32)),
+
+  ERROR(NS_XSLT_GET_NEW_HANDLER,  SUCCESS(1)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 28: NS_ERROR_MODULE_IPC */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_IPC
+  // Initial creation of a Transport object failed internally for unknown reasons.
+  ERROR(NS_ERROR_TRANSPORT_INIT,          FAILURE(1)),
+  // Generic error related to duplicating handle failures.
+  ERROR(NS_ERROR_DUPLICATE_HANDLE,        FAILURE(2)),
+  // Bridging: failure trying to open the connection to the parent
+  ERROR(NS_ERROR_BRIDGE_OPEN_PARENT,      FAILURE(3)),
+  // Bridging: failure trying to open the connection to the child
+  ERROR(NS_ERROR_BRIDGE_OPEN_CHILD,       FAILURE(4)),
+#undef MODULE
+
+  /* ======================================================================= */
+  /* 29: NS_ERROR_MODULE_SVG */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_SVG
+  /* SVG DOM error codes from http://www.w3.org/TR/SVG11/svgdom.html */
+  ERROR(NS_ERROR_DOM_SVG_WRONG_TYPE_ERR,         FAILURE(0)),
+  /* Yes, the spec says "INVERTABLE", not "INVERTIBLE" */
+  ERROR(NS_ERROR_DOM_SVG_MATRIX_NOT_INVERTABLE,  FAILURE(2)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 30: NS_ERROR_MODULE_STORAGE */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_STORAGE
+  /* To add additional errors to Storage, please append entries to the bottom
+   * of the list in the following format:
+   *   NS_ERROR_STORAGE_YOUR_ERR,  FAILURE(n)
+   * where n is the next unique positive integer.  You must also add an entry
+   * to js/xpconnect/src/xpc.msg under the code block beginning with the
+   * comment 'storage related codes (from mozStorage.h)', in the following
+   * format: 'XPC_MSG_DEF(NS_ERROR_STORAGE_YOUR_ERR, "brief description of your
+   * error")' */
+  ERROR(NS_ERROR_STORAGE_BUSY,        FAILURE(1)),
+  ERROR(NS_ERROR_STORAGE_IOERR,       FAILURE(2)),
+  ERROR(NS_ERROR_STORAGE_CONSTRAINT,  FAILURE(3)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 32: NS_ERROR_MODULE_DOM_FILE */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_DOM_FILE
+  ERROR(NS_ERROR_DOM_FILE_NOT_FOUND_ERR,     FAILURE(0)),
+  ERROR(NS_ERROR_DOM_FILE_NOT_READABLE_ERR,  FAILURE(1)),
+  ERROR(NS_ERROR_DOM_FILE_ABORT_ERR,         FAILURE(2)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 33: NS_ERROR_MODULE_DOM_INDEXEDDB */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_DOM_INDEXEDDB
+  /* IndexedDB error codes http://dvcs.w3.org/hg/IndexedDB/raw-file/tip/Overview.html */
+  ERROR(NS_ERROR_DOM_INDEXEDDB_UNKNOWN_ERR,               FAILURE(1)),
+  ERROR(NS_ERROR_DOM_INDEXEDDB_NOT_FOUND_ERR,             FAILURE(3)),
+  ERROR(NS_ERROR_DOM_INDEXEDDB_CONSTRAINT_ERR,            FAILURE(4)),
+  ERROR(NS_ERROR_DOM_INDEXEDDB_DATA_ERR,                  FAILURE(5)),
+  ERROR(NS_ERROR_DOM_INDEXEDDB_NOT_ALLOWED_ERR,           FAILURE(6)),
+  ERROR(NS_ERROR_DOM_INDEXEDDB_TRANSACTION_INACTIVE_ERR,  FAILURE(7)),
+  ERROR(NS_ERROR_DOM_INDEXEDDB_ABORT_ERR,                 FAILURE(8)),
+  ERROR(NS_ERROR_DOM_INDEXEDDB_READ_ONLY_ERR,             FAILURE(9)),
+  ERROR(NS_ERROR_DOM_INDEXEDDB_TIMEOUT_ERR,               FAILURE(10)),
+  ERROR(NS_ERROR_DOM_INDEXEDDB_QUOTA_ERR,                 FAILURE(11)),
+  ERROR(NS_ERROR_DOM_INDEXEDDB_VERSION_ERR,               FAILURE(12)),
+  ERROR(NS_ERROR_DOM_INDEXEDDB_RECOVERABLE_ERR,           FAILURE(1001)),
+#undef MODULE
+
+
+  /* ======================================================================= */
+  /* 34: NS_ERROR_MODULE_DOM_FILEHANDLE */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_DOM_FILEHANDLE
+  ERROR(NS_ERROR_DOM_FILEHANDLE_UNKNOWN_ERR,              FAILURE(1)),
+  ERROR(NS_ERROR_DOM_FILEHANDLE_NOT_ALLOWED_ERR,          FAILURE(2)),
+  ERROR(NS_ERROR_DOM_FILEHANDLE_INACTIVE_ERR,             FAILURE(3)),
+  ERROR(NS_ERROR_DOM_FILEHANDLE_ABORT_ERR,                FAILURE(4)),
+  ERROR(NS_ERROR_DOM_FILEHANDLE_READ_ONLY_ERR,            FAILURE(5)),
+  ERROR(NS_ERROR_DOM_FILEHANDLE_QUOTA_ERR,                FAILURE(6)),
+#undef MODULE
+
+  /* ======================================================================= */
+  /* 35: NS_ERROR_MODULE_SIGNED_JAR */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_SIGNED_JAR
+  ERROR(NS_ERROR_SIGNED_JAR_NOT_SIGNED,                   FAILURE(1)),
+  ERROR(NS_ERROR_SIGNED_JAR_MODIFIED_ENTRY,               FAILURE(2)),
+  ERROR(NS_ERROR_SIGNED_JAR_UNSIGNED_ENTRY,               FAILURE(3)),
+  ERROR(NS_ERROR_SIGNED_JAR_ENTRY_MISSING,                FAILURE(4)),
+  ERROR(NS_ERROR_SIGNED_JAR_WRONG_SIGNATURE,              FAILURE(5)),
+  ERROR(NS_ERROR_SIGNED_JAR_ENTRY_TOO_LARGE,              FAILURE(6)),
+  ERROR(NS_ERROR_SIGNED_JAR_ENTRY_INVALID,                FAILURE(7)),
+  ERROR(NS_ERROR_SIGNED_JAR_MANIFEST_INVALID,             FAILURE(8)),
+#undef MODULE
+
+  /* ======================================================================= */
+  /* 36: NS_ERROR_MODULE_DOM_FILESYSTEM */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_DOM_FILESYSTEM
+  ERROR(NS_ERROR_DOM_FILESYSTEM_INVALID_PATH_ERR,          FAILURE(1)),
+  ERROR(NS_ERROR_DOM_FILESYSTEM_INVALID_MODIFICATION_ERR,  FAILURE(2)),
+  ERROR(NS_ERROR_DOM_FILESYSTEM_NO_MODIFICATION_ALLOWED_ERR, FAILURE(3)),
+  ERROR(NS_ERROR_DOM_FILESYSTEM_PATH_EXISTS_ERR,           FAILURE(4)),
+  ERROR(NS_ERROR_DOM_FILESYSTEM_TYPE_MISMATCH_ERR,         FAILURE(5)),
+  ERROR(NS_ERROR_DOM_FILESYSTEM_UNKNOWN_ERR,               FAILURE(6)),
+#undef MODULE
+
+  /* ======================================================================= */
+  /* 38: NS_ERROR_MODULE_SIGNED_APP */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_SIGNED_APP
+  ERROR(NS_ERROR_SIGNED_APP_MANIFEST_INVALID,   FAILURE(1)),
+#undef MODULE
+
+  /* ======================================================================= */
+  /* 39: NS_ERROR_MODULE_DOM_ANIM */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_DOM_ANIM
+  ERROR(NS_ERROR_DOM_ANIM_MISSING_PROPS_ERR,              FAILURE(1)),
+#undef MODULE
+
+  /* ======================================================================= */
+  /* 40: NS_ERROR_MODULE_DOM_PUSH */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_DOM_PUSH
+  ERROR(NS_ERROR_DOM_PUSH_INVALID_REGISTRATION_ERR, FAILURE(1)),
+  ERROR(NS_ERROR_DOM_PUSH_DENIED_ERR,               FAILURE(2)),
+  ERROR(NS_ERROR_DOM_PUSH_ABORT_ERR,                FAILURE(3)),
+  ERROR(NS_ERROR_DOM_PUSH_SERVICE_UNREACHABLE,      FAILURE(4)),
+  ERROR(NS_ERROR_DOM_PUSH_INVALID_KEY_ERR,          FAILURE(5)),
+  ERROR(NS_ERROR_DOM_PUSH_MISMATCHED_KEY_ERR,       FAILURE(6)),
+#undef MODULE
+
+  /* ======================================================================= */
+  /* 41: NS_ERROR_MODULE_DOM_MEDIA */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_DOM_MEDIA
+  /* HTMLMediaElement API errors from https://html.spec.whatwg.org/multipage/embedded-content.html#media-elements */
+  ERROR(NS_ERROR_DOM_MEDIA_ABORT_ERR,           FAILURE(1)),
+  ERROR(NS_ERROR_DOM_MEDIA_NOT_ALLOWED_ERR,     FAILURE(2)),
+  ERROR(NS_ERROR_DOM_MEDIA_NOT_SUPPORTED_ERR,   FAILURE(3)),
+
+  /* HTMLMediaElement internal decoding error */
+  ERROR(NS_ERROR_DOM_MEDIA_DECODE_ERR,          FAILURE(4)),
+  ERROR(NS_ERROR_DOM_MEDIA_FATAL_ERR,           FAILURE(5)),
+  ERROR(NS_ERROR_DOM_MEDIA_METADATA_ERR,        FAILURE(6)),
+  ERROR(NS_ERROR_DOM_MEDIA_OVERFLOW_ERR,        FAILURE(7)),
+  ERROR(NS_ERROR_DOM_MEDIA_END_OF_STREAM,       FAILURE(8)),
+  ERROR(NS_ERROR_DOM_MEDIA_WAITING_FOR_DATA,    FAILURE(9)),
+  ERROR(NS_ERROR_DOM_MEDIA_CANCELED,            FAILURE(10)),
+  ERROR(NS_ERROR_DOM_MEDIA_MEDIASINK_ERR,       FAILURE(11)),
+  ERROR(NS_ERROR_DOM_MEDIA_DEMUXER_ERR,         FAILURE(12)),
+  ERROR(NS_ERROR_DOM_MEDIA_CDM_ERR,             FAILURE(13)),
+  ERROR(NS_ERROR_DOM_MEDIA_NEED_NEW_DECODER,    FAILURE(14)),
+
+  /* Internal platform-related errors */
+  ERROR(NS_ERROR_DOM_MEDIA_CUBEB_INITIALIZATION_ERR,  FAILURE(101)),
+#undef MODULE
+
+  /* ======================================================================= */
+  /* 51: NS_ERROR_MODULE_GENERAL */
+  /* ======================================================================= */
+#define MODULE NS_ERROR_MODULE_GENERAL
+  /* Error code used internally by the incremental downloader to cancel the
+   * network channel when the download is already complete. */
+  ERROR(NS_ERROR_DOWNLOAD_COMPLETE,      FAILURE(1)),
+  /* Error code used internally by the incremental downloader to cancel the
+   * network channel when the response to a range request is 200 instead of
+   * 206. */
+  ERROR(NS_ERROR_DOWNLOAD_NOT_PARTIAL,   FAILURE(2)),
+  ERROR(NS_ERROR_UNORM_MOREOUTPUT,       FAILURE(33)),
+
+  ERROR(NS_ERROR_DOCSHELL_REQUEST_REJECTED,  FAILURE(1001)),
+  /* This is needed for displaying an error message when navigation is
+   * attempted on a document when printing The value arbitrary as long as it
+   * doesn't conflict with any of the other values in the errors in
+   * DisplayLoadError */
+  ERROR(NS_ERROR_DOCUMENT_IS_PRINTMODE,  FAILURE(2001)),
+
+  ERROR(NS_SUCCESS_DONT_FIXUP,           SUCCESS(1)),
+  /* This success code may be returned by nsIAppStartup::Run to indicate that
+   * the application should be restarted.  This condition corresponds to the
+   * case in which nsIAppStartup::Quit was called with the eRestart flag. */
+  ERROR(NS_SUCCESS_RESTART_APP,          SUCCESS(1)),
+  ERROR(NS_SUCCESS_RESTART_APP_NOT_SAME_PROFILE,    SUCCESS(3)),
+  ERROR(NS_SUCCESS_UNORM_NOTFOUND,  SUCCESS(17)),
+
+
+  /* a11y */
+  /* raised when current pivot's position is needed but it's not in the tree */
+  ERROR(NS_ERROR_NOT_IN_TREE,  FAILURE(38)),
+
+  /* see nsTextEquivUtils */
+  ERROR(NS_OK_NO_NAME_CLAUSE_HANDLED,  SUCCESS(34))
+#undef MODULE
diff --git a/xpcom/base/ErrorNames.cpp b/xpcom/base/ErrorNames.cpp
new file mode 100644
index 000000000..165a1a0fc
--- /dev/null
+++ b/xpcom/base/ErrorNames.cpp
@@ -0,0 +1,84 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/ErrorNames.h"
+#include "nsString.h"
+#include "prerror.h"
+
+namespace {
+
+struct ErrorEntry
+{
+  nsresult value;
+  const char * name;
+};
+
+#undef ERROR
+#define ERROR(key, val) {key, #key}
+
+const ErrorEntry errors[] = {
+  #include "ErrorList.h"
+};
+
+#undef ERROR
+
+} // unnamed namespace
+
+namespace mozilla {
+
+void
+GetErrorName(nsresult rv, nsACString& name)
+{
+  for (size_t i = 0; i < ArrayLength(errors); ++i) {
+    if (errors[i].value == rv) {
+      name.AssignASCII(errors[i].name);
+      return;
+    }
+  }
+
+  bool isSecurityError = NS_ERROR_GET_MODULE(rv) == NS_ERROR_MODULE_SECURITY;
+
+  // NS_ERROR_MODULE_SECURITY is the only module that is "allowed" to
+  // synthesize nsresult error codes that are not listed in ErrorList.h. (The
+  // NS_ERROR_MODULE_SECURITY error codes are synthesized from NSPR error
+  // codes.)
+  MOZ_ASSERT(isSecurityError);
+
+  name.AssignASCII(NS_SUCCEEDED(rv) ? "NS_ERROR_GENERATE_SUCCESS("
+                                    : "NS_ERROR_GENERATE_FAILURE(");
+
+  if (isSecurityError) {
+    name.AppendASCII("NS_ERROR_MODULE_SECURITY");
+  } else {
+    // This should never happen given the assertion above, so we don't bother
+    // trying to print a symbolic name for the module here.
+    name.AppendInt(NS_ERROR_GET_MODULE(rv));
+  }
+
+  name.AppendASCII(", ");
+
+  const char * nsprName = nullptr;
+  if (isSecurityError) {
+    // Invert the logic from NSSErrorsService::GetXPCOMFromNSSError
+    PRErrorCode nsprCode
+      = -1 * static_cast<PRErrorCode>(NS_ERROR_GET_CODE(rv));
+    nsprName = PR_ErrorToName(nsprCode);
+
+    // All NSPR error codes defined by NSPR or NSS should have a name mapping.
+    MOZ_ASSERT(nsprName);
+  }
+
+  if (nsprName) {
+    name.AppendASCII(nsprName);
+  } else {
+    name.AppendInt(NS_ERROR_GET_CODE(rv));
+  }
+
+  name.AppendASCII(")");
+}
+
+} // namespace mozilla
diff --git a/xpcom/base/ErrorNames.h b/xpcom/base/ErrorNames.h
new file mode 100644
index 000000000..9fdba7ace
--- /dev/null
+++ b/xpcom/base/ErrorNames.h
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_ErrorNames_h
+#define mozilla_ErrorNames_h
+
+#include "nsError.h"
+
+class nsACString;
+
+namespace mozilla {
+
+// Maps the given nsresult to its symbolic name. For example,
+// GetErrorName(NS_OK, name) will result in name == "NS_OK".
+// When the symbolic name is unknown, name will be of the form
+// "NS_ERROR_GENERATE_SUCCESS(<module>, <code>)" or
+// "NS_ERROR_GENERATE_FAILURE(<module>, <code>)".
+void GetErrorName(nsresult rv, nsACString& name);
+
+} // namespace mozilla
+
+#endif // mozilla_ErrorNames_h
diff --git a/xpcom/base/HoldDropJSObjects.cpp b/xpcom/base/HoldDropJSObjects.cpp
new file mode 100644
index 000000000..eeecc7121
--- /dev/null
+++ b/xpcom/base/HoldDropJSObjects.cpp
@@ -0,0 +1,68 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/HoldDropJSObjects.h"
+
+#include "mozilla/Assertions.h"
+#include "mozilla/CycleCollectedJSContext.h"
+
+namespace mozilla {
+namespace cyclecollector {
+
+void
+HoldJSObjectsImpl(void* aHolder, nsScriptObjectTracer* aTracer)
+{
+  CycleCollectedJSContext* cx = CycleCollectedJSContext::Get();
+  MOZ_ASSERT(cx, "Should have a CycleCollectedJSContext by now");
+  cx->AddJSHolder(aHolder, aTracer);
+}
+
+void
+HoldJSObjectsImpl(nsISupports* aHolder)
+{
+  nsXPCOMCycleCollectionParticipant* participant = nullptr;
+  CallQueryInterface(aHolder, &participant);
+  MOZ_ASSERT(participant, "Failed to QI to nsXPCOMCycleCollectionParticipant!");
+  MOZ_ASSERT(participant->CheckForRightISupports(aHolder),
+             "The result of QIing a JS holder should be the same as ToSupports");
+
+  HoldJSObjectsImpl(aHolder, participant);
+}
+
+void
+DropJSObjectsImpl(void* aHolder)
+{
+  CycleCollectedJSContext* cx = CycleCollectedJSContext::Get();
+  MOZ_ASSERT(cx, "Should have a CycleCollectedJSContext by now");
+  cx->RemoveJSHolder(aHolder);
+}
+
+void
+DropJSObjectsImpl(nsISupports* aHolder)
+{
+#ifdef DEBUG
+  nsXPCOMCycleCollectionParticipant* participant = nullptr;
+  CallQueryInterface(aHolder, &participant);
+  MOZ_ASSERT(participant, "Failed to QI to nsXPCOMCycleCollectionParticipant!");
+  MOZ_ASSERT(participant->CheckForRightISupports(aHolder),
+             "The result of QIing a JS holder should be the same as ToSupports");
+#endif
+  DropJSObjectsImpl(static_cast<void*>(aHolder));
+}
+
+} // namespace cyclecollector
+
+#ifdef DEBUG
+bool
+IsJSHolder(void* aHolder)
+{
+  CycleCollectedJSContext* cx = CycleCollectedJSContext::Get();
+  MOZ_ASSERT(cx, "Should have a CycleCollectedJSContext by now");
+  return cx->IsJSHolder(aHolder);
+}
+#endif
+
+} // namespace mozilla
diff --git a/xpcom/base/HoldDropJSObjects.h b/xpcom/base/HoldDropJSObjects.h
new file mode 100644
index 000000000..1a500a94a
--- /dev/null
+++ b/xpcom/base/HoldDropJSObjects.h
@@ -0,0 +1,77 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_HoldDropJSObjects_h
+#define mozilla_HoldDropJSObjects_h
+
+#include "mozilla/TypeTraits.h"
+#include "nsCycleCollectionParticipant.h"
+
+class nsISupports;
+class nsScriptObjectTracer;
+
+// Only HoldJSObjects and DropJSObjects should be called directly.
+
+namespace mozilla {
+namespace cyclecollector {
+
+void HoldJSObjectsImpl(void* aHolder, nsScriptObjectTracer* aTracer);
+void HoldJSObjectsImpl(nsISupports* aHolder);
+void DropJSObjectsImpl(void* aHolder);
+void DropJSObjectsImpl(nsISupports* aHolder);
+
+} // namespace cyclecollector
+
+
+template<class T, bool isISupports = IsBaseOf<nsISupports, T>::value>
+struct HoldDropJSObjectsHelper
+{
+  static void Hold(T* aHolder)
+  {
+    cyclecollector::HoldJSObjectsImpl(aHolder,
+                                      NS_CYCLE_COLLECTION_PARTICIPANT(T));
+  }
+  static void Drop(T* aHolder)
+  {
+    cyclecollector::DropJSObjectsImpl(aHolder);
+  }
+};
+
+template<class T>
+struct HoldDropJSObjectsHelper<T, true>
+{
+  static void Hold(T* aHolder)
+  {
+    cyclecollector::HoldJSObjectsImpl(ToSupports(aHolder));
+  }
+  static void Drop(T* aHolder)
+  {
+    cyclecollector::DropJSObjectsImpl(ToSupports(aHolder));
+  }
+};
+
+
+template<class T>
+void
+HoldJSObjects(T* aHolder)
+{
+  HoldDropJSObjectsHelper<T>::Hold(aHolder);
+}
+
+template<class T>
+void
+DropJSObjects(T* aHolder)
+{
+  HoldDropJSObjectsHelper<T>::Drop(aHolder);
+}
+
+#ifdef DEBUG
+bool IsJSHolder(void* aHolder);
+#endif
+
+} // namespace mozilla
+
+#endif // mozilla_HoldDropJSObjects_h
diff --git a/xpcom/base/JSObjectHolder.cpp b/xpcom/base/JSObjectHolder.cpp
new file mode 100644
index 000000000..5bcc3cabb
--- /dev/null
+++ b/xpcom/base/JSObjectHolder.cpp
@@ -0,0 +1,9 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "JSObjectHolder.h"
+
+NS_IMPL_ISUPPORTS(mozilla::JSObjectHolder, nsISupports)
diff --git a/xpcom/base/JSObjectHolder.h b/xpcom/base/JSObjectHolder.h
new file mode 100644
index 000000000..7b83b813d
--- /dev/null
+++ b/xpcom/base/JSObjectHolder.h
@@ -0,0 +1,42 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_JSObjectHolder_h
+#define mozilla_JSObjectHolder_h
+
+#include "js/RootingAPI.h"
+#include "nsISupportsImpl.h"
+
+namespace mozilla {
+
+// This class is useful when something on one thread needs to keep alive
+// a JS Object from another thread. If they are both on the same thread, the
+// owning class should instead be made a cycle collected SCRIPT_HOLDER class.
+// This object should only be AddRefed and Released on the same thread as
+// mJSObject.
+//
+// Note that this keeps alive the JS object until it goes away, so be sure not to
+// create cycles that keep alive the holder.
+//
+// JSObjectHolder is ISupports to make it usable with NS_ReleaseOnMainThread.
+class JSObjectHolder final : public nsISupports
+{
+public:
+  JSObjectHolder(JSContext* aCx, JSObject* aObject) : mJSObject(aCx, aObject) {}
+
+  NS_DECL_ISUPPORTS
+
+  JSObject* GetJSObject() { return mJSObject; }
+
+private:
+  ~JSObjectHolder() {}
+
+  JS::PersistentRooted<JSObject*> mJSObject;
+};
+
+} // namespace mozilla
+
+#endif // mozilla_JSObjectHolder_h
diff --git a/xpcom/base/LinuxUtils.cpp b/xpcom/base/LinuxUtils.cpp
new file mode 100644
index 000000000..331c82be9
--- /dev/null
+++ b/xpcom/base/LinuxUtils.cpp
@@ -0,0 +1,50 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "LinuxUtils.h"
+
+#if defined(XP_LINUX)
+
+#include <ctype.h>
+#include <stdio.h>
+
+#include "nsPrintfCString.h"
+
+namespace mozilla {
+
+void
+LinuxUtils::GetThreadName(pid_t aTid, nsACString& aName)
+{
+  aName.Truncate();
+  if (aTid <= 0) {
+    return;
+  }
+
+  const size_t kBuffSize = 16; // 15 chars max + '\n'
+  char buf[kBuffSize];
+  nsPrintfCString path("/proc/%d/comm", aTid);
+  FILE* fp = fopen(path.get(), "r");
+  if (!fp) {
+    // The fopen could also fail if the thread exited before we got here.
+    return;
+  }
+
+  size_t len = fread(buf, 1, kBuffSize, fp);
+  fclose(fp);
+
+  // No need to strip the '\n', since isspace() includes it.
+  while (len > 0 &&
+         (isspace(buf[len - 1]) || isdigit(buf[len - 1]) ||
+          buf[len - 1] == '#' || buf[len - 1] == '_')) {
+    --len;
+  }
+
+  aName.Assign(buf, len);
+}
+
+}
+
+#endif // XP_LINUX
diff --git a/xpcom/base/LinuxUtils.h b/xpcom/base/LinuxUtils.h
new file mode 100644
index 000000000..e82c15e08
--- /dev/null
+++ b/xpcom/base/LinuxUtils.h
@@ -0,0 +1,34 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_LinuxUtils_h
+#define mozilla_LinuxUtils_h
+
+#if defined(XP_LINUX)
+
+#include <unistd.h>
+#include "nsString.h"
+
+namespace mozilla {
+
+class LinuxUtils
+{
+public:
+  // Obtain the name of a thread, omitting any numeric suffix added by a
+  // thread pool library (as in, e.g., "Binder_2" or "mozStorage #1").
+  // The empty string is returned on error.
+  //
+  // Note: if this is ever needed on kernels older than 2.6.33 (early 2010),
+  // it will have to parse /proc/<pid>/status instead, because
+  // /proc/<pid>/comm didn't exist before then.
+  static void GetThreadName(pid_t aTid, nsACString& aName);
+};
+
+}
+
+#endif // XP_LINUX
+
+#endif
diff --git a/xpcom/base/LogModulePrefWatcher.cpp b/xpcom/base/LogModulePrefWatcher.cpp
new file mode 100644
index 000000000..bd04eda98
--- /dev/null
+++ b/xpcom/base/LogModulePrefWatcher.cpp
@@ -0,0 +1,170 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "LogModulePrefWatcher.h"
+
+#include "mozilla/Logging.h"
+#include "mozilla/Preferences.h"
+#include "nsString.h"
+#include "nsXULAppAPI.h"
+#include "base/process_util.h"
+
+static const char kLoggingPrefPrefix[] = "logging.";
+static const char kLoggingConfigPrefPrefix[] = "logging.config";
+static const int  kLoggingConfigPrefixLen = sizeof(kLoggingConfigPrefPrefix) - 1;
+static const char kLoggingPrefClearOnStartup[] = "logging.config.clear_on_startup";
+static const char kLoggingPrefLogFile[] = "logging.config.LOG_FILE";
+static const char kLoggingPrefAddTimestamp[] = "logging.config.add_timestamp";
+static const char kLoggingPrefSync[] = "logging.config.sync";
+
+namespace mozilla {
+
+NS_IMPL_ISUPPORTS(LogModulePrefWatcher, nsIObserver)
+
+/**
+ * Resets all the preferences in the logging. branch
+ * This is needed because we may crash while logging, and this would cause us
+ * to log after restarting as well.
+ *
+ * If logging after restart is desired, set the logging.config.clear_on_startup
+ * pref to false, or use the MOZ_LOG_FILE and MOZ_LOG_MODULES env vars.
+ */
+void ResetExistingPrefs()
+{
+  uint32_t count;
+  char** names;
+  nsresult rv = Preferences::GetRootBranch()->
+      GetChildList(kLoggingPrefPrefix, &count, &names);
+  if (NS_SUCCEEDED(rv) && count) {
+    for (size_t i = 0; i < count; i++) {
+      // Clearing the pref will cause it to reload, thus resetting the log level
+      Preferences::ClearUser(names[i]);
+    }
+    NS_FREE_XPCOM_ALLOCATED_POINTER_ARRAY(count, names);
+  }
+}
+
+/**
+ * Loads the log level from the given pref and updates the corresponding
+ * LogModule.
+ */
+static void
+LoadPrefValue(const char* aName)
+{
+  LogLevel logLevel = LogLevel::Disabled;
+
+  nsresult rv;
+  int32_t prefLevel = 0;
+  nsAutoCString prefValue;
+
+  if (strncmp(aName, kLoggingConfigPrefPrefix, kLoggingConfigPrefixLen) == 0) {
+    nsAutoCString prefName(aName);
+
+    if (prefName.EqualsLiteral(kLoggingPrefLogFile)) {
+      rv = Preferences::GetCString(aName, &prefValue);
+      // The pref was reset. Clear the user file.
+      if (NS_FAILED(rv) || prefValue.IsEmpty()) {
+        LogModule::SetLogFile(nullptr);
+        return;
+      }
+
+      // If the pref value doesn't have a PID placeholder, append it to the end.
+      if (!strstr(prefValue.get(), "%PID")) {
+        prefValue.Append("%PID");
+      }
+
+      LogModule::SetLogFile(prefValue.BeginReading());
+    } else if (prefName.EqualsLiteral(kLoggingPrefAddTimestamp)) {
+      bool addTimestamp = Preferences::GetBool(aName, false);
+      LogModule::SetAddTimestamp(addTimestamp);
+    } else if (prefName.EqualsLiteral(kLoggingPrefSync)) {
+      bool sync = Preferences::GetBool(aName, false);
+      LogModule::SetIsSync(sync);
+    }
+    return;
+  }
+
+  if (Preferences::GetInt(aName, &prefLevel) == NS_OK) {
+    logLevel = ToLogLevel(prefLevel);
+  } else if (Preferences::GetCString(aName, &prefValue) == NS_OK) {
+    if (prefValue.LowerCaseEqualsLiteral("error")) {
+      logLevel = LogLevel::Error;
+    } else if (prefValue.LowerCaseEqualsLiteral("warning")) {
+      logLevel = LogLevel::Warning;
+    } else if (prefValue.LowerCaseEqualsLiteral("info")) {
+      logLevel = LogLevel::Info;
+    } else if (prefValue.LowerCaseEqualsLiteral("debug")) {
+      logLevel = LogLevel::Debug;
+    } else if (prefValue.LowerCaseEqualsLiteral("verbose")) {
+      logLevel = LogLevel::Verbose;
+    }
+  }
+
+  const char* moduleName = aName + strlen(kLoggingPrefPrefix);
+  LogModule::Get(moduleName)->SetLevel(logLevel);
+}
+
+void
+LoadExistingPrefs()
+{
+  nsIPrefBranch* root = Preferences::GetRootBranch();
+  if (!root) {
+    return;
+  }
+
+  uint32_t count;
+  char** names;
+  nsresult rv = root->GetChildList(kLoggingPrefPrefix, &count, &names);
+  if (NS_SUCCEEDED(rv) && count) {
+    for (size_t i = 0; i < count; i++) {
+      LoadPrefValue(names[i]);
+    }
+    NS_FREE_XPCOM_ALLOCATED_POINTER_ARRAY(count, names);
+  }
+}
+
+LogModulePrefWatcher::LogModulePrefWatcher()
+{
+}
+
+void
+LogModulePrefWatcher::RegisterPrefWatcher()
+{
+  RefPtr<LogModulePrefWatcher> prefWatcher = new LogModulePrefWatcher();
+  Preferences::AddStrongObserver(prefWatcher, kLoggingPrefPrefix);
+
+  nsCOMPtr<nsIObserverService> observerService =
+    mozilla::services::GetObserverService();
+  if (observerService && XRE_IsParentProcess()) {
+    observerService->AddObserver(prefWatcher, "browser-delayed-startup-finished", false);
+  }
+
+  LoadExistingPrefs();
+}
+
+NS_IMETHODIMP
+LogModulePrefWatcher::Observe(nsISupports* aSubject, const char* aTopic,
+                              const char16_t* aData)
+{
+  if (strcmp(NS_PREFBRANCH_PREFCHANGE_TOPIC_ID, aTopic) == 0) {
+    NS_LossyConvertUTF16toASCII prefName(aData);
+    LoadPrefValue(prefName.get());
+  } else if (strcmp("browser-delayed-startup-finished", aTopic) == 0) {
+    bool clear = Preferences::GetBool(kLoggingPrefClearOnStartup, true);
+    if (clear) {
+      ResetExistingPrefs();
+    }
+    nsCOMPtr<nsIObserverService> observerService =
+      mozilla::services::GetObserverService();
+    if (observerService) {
+      observerService->RemoveObserver(this, "browser-delayed-startup-finished");
+    }
+  }
+
+  return NS_OK;
+}
+
+} // namespace mozilla
diff --git a/xpcom/base/LogModulePrefWatcher.h b/xpcom/base/LogModulePrefWatcher.h
new file mode 100644
index 000000000..657e54f01
--- /dev/null
+++ b/xpcom/base/LogModulePrefWatcher.h
@@ -0,0 +1,42 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef LogModulePrefWatcher_h
+#define LogModulePrefWatcher_h
+
+#include "nsIObserver.h"
+
+namespace mozilla {
+
+/**
+ * Watches for changes to "logging.*" prefs and then updates the appropriate
+ * LogModule's log level. Both the integer and string versions of the LogLevel
+ * enum are supported.
+ *
+ * For example setting the pref "logging.Foo" to "Verbose" will set the
+ * LogModule for "Foo" to the LogLevel::Verbose level. Setting "logging.Bar" to
+ * 4 would set the LogModule for "Bar" to the LogLevel::Debug level.
+ */
+class LogModulePrefWatcher : public nsIObserver
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+
+  /**
+   * Starts observing logging pref changes.
+   */
+  static void RegisterPrefWatcher();
+
+private:
+  LogModulePrefWatcher();
+  virtual ~LogModulePrefWatcher()
+  {
+  }
+};
+} // namespace mozilla
+
+#endif // LogModulePrefWatcher_h
diff --git a/xpcom/base/Logging.cpp b/xpcom/base/Logging.cpp
new file mode 100644
index 000000000..e87df91e4
--- /dev/null
+++ b/xpcom/base/Logging.cpp
@@ -0,0 +1,568 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Logging.h"
+
+#include <algorithm>
+
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/FileUtils.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/Sprintf.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/UniquePtrExtensions.h"
+#include "nsClassHashtable.h"
+#include "nsDebug.h"
+#include "NSPRLogModulesParser.h"
+
+#include "prenv.h"
+#include "prprf.h"
+#ifdef XP_WIN
+#include <process.h>
+#else
+#include <sys/types.h>
+#include <unistd.h>
+#endif
+
+// NB: Initial amount determined by auditing the codebase for the total amount
+//     of unique module names and padding up to the next power of 2.
+const uint32_t kInitialModuleCount = 256;
+// When rotate option is added to the modules list, this is the hardcoded
+// number of files we create and rotate.  When there is rotate:40,
+// we will keep four files per process, each limited to 10MB.  Sum is 40MB,
+// the given limit.
+const uint32_t kRotateFilesNumber = 4;
+
+namespace mozilla {
+
+namespace detail {
+
+void log_print(const PRLogModuleInfo* aModule,
+               LogLevel aLevel,
+               const char* aFmt, ...)
+{
+  va_list ap;
+  va_start(ap, aFmt);
+  char* buff = PR_vsmprintf(aFmt, ap);
+  PR_LogPrint("%s", buff);
+  PR_smprintf_free(buff);
+  va_end(ap);
+}
+
+void log_print(const LogModule* aModule,
+               LogLevel aLevel,
+               const char* aFmt, ...)
+{
+  va_list ap;
+  va_start(ap, aFmt);
+  aModule->Printv(aLevel, aFmt, ap);
+  va_end(ap);
+}
+
+} // detail
+
+LogLevel
+ToLogLevel(int32_t aLevel)
+{
+  aLevel = std::min(aLevel, static_cast<int32_t>(LogLevel::Verbose));
+  aLevel = std::max(aLevel, static_cast<int32_t>(LogLevel::Disabled));
+  return static_cast<LogLevel>(aLevel);
+}
+
+const char*
+ToLogStr(LogLevel aLevel) {
+  switch (aLevel) {
+    case LogLevel::Error:
+      return "E";
+    case LogLevel::Warning:
+      return "W";
+    case LogLevel::Info:
+      return "I";
+    case LogLevel::Debug:
+      return "D";
+    case LogLevel::Verbose:
+      return "V";
+    case LogLevel::Disabled:
+    default:
+      MOZ_CRASH("Invalid log level.");
+      return "";
+  }
+}
+
+namespace detail {
+
+/**
+ * A helper class providing reference counting for FILE*.
+ * It encapsulates the following:
+ *  - the FILE handle
+ *  - the order number it was created for when rotating (actual path)
+ *  - number of active references
+ */
+class LogFile
+{
+  FILE* mFile;
+  uint32_t mFileNum;
+
+public:
+  LogFile(FILE* aFile, uint32_t aFileNum)
+    : mFile(aFile)
+    , mFileNum(aFileNum)
+    , mNextToRelease(nullptr)
+  {
+  }
+
+  ~LogFile()
+  {
+    fclose(mFile);
+    delete mNextToRelease;
+  }
+
+  FILE* File() const { return mFile; }
+  uint32_t Num() const { return mFileNum; }
+
+  LogFile* mNextToRelease;
+};
+
+const char*
+ExpandPIDMarker(const char* aFilename, char (&buffer)[2048])
+{
+  MOZ_ASSERT(aFilename);
+  static const char kPIDToken[] = "%PID";
+  const char* pidTokenPtr = strstr(aFilename, kPIDToken);
+  if (pidTokenPtr &&
+    SprintfLiteral(buffer, "%.*s%s%d%s",
+                   static_cast<int>(pidTokenPtr - aFilename), aFilename,
+                   XRE_IsParentProcess() ? "-main." : "-child.",
+                   base::GetCurrentProcId(),
+                   pidTokenPtr + strlen(kPIDToken)) > 0)
+  {
+    return buffer;
+  }
+
+  return aFilename;
+}
+
+} // detail
+
+namespace {
+  // Helper method that initializes an empty va_list to be empty.
+  void empty_va(va_list *va, ...)
+  {
+    va_start(*va, va);
+    va_end(*va);
+  }
+}
+
+class LogModuleManager
+{
+public:
+  LogModuleManager()
+    : mModulesLock("logmodules")
+    , mModules(kInitialModuleCount)
+    , mPrintEntryCount(0)
+    , mOutFile(nullptr)
+    , mToReleaseFile(nullptr)
+    , mOutFileNum(0)
+    , mOutFilePath(strdup(""))
+    , mMainThread(PR_GetCurrentThread())
+    , mSetFromEnv(false)
+    , mAddTimestamp(false)
+    , mIsSync(false)
+    , mRotate(0)
+  {
+  }
+
+  ~LogModuleManager()
+  {
+    detail::LogFile* logFile = mOutFile.exchange(nullptr);
+    delete logFile;
+  }
+
+  /**
+   * Loads config from env vars if present.
+   */
+  void Init()
+  {
+    bool shouldAppend = false;
+    bool addTimestamp = false;
+    bool isSync = false;
+    int32_t rotate = 0;
+    const char* modules = PR_GetEnv("MOZ_LOG");
+    if (!modules || !modules[0]) {
+      modules = PR_GetEnv("MOZ_LOG_MODULES");
+      if (modules) {
+        NS_WARNING("MOZ_LOG_MODULES is deprecated."
+            "\nPlease use MOZ_LOG instead.");
+      }
+    }
+    if (!modules || !modules[0]) {
+      modules = PR_GetEnv("NSPR_LOG_MODULES");
+      if (modules) {
+        NS_WARNING("NSPR_LOG_MODULES is deprecated."
+            "\nPlease use MOZ_LOG instead.");
+      }
+    }
+
+    NSPRLogModulesParser(modules,
+        [&shouldAppend, &addTimestamp, &isSync, &rotate]
+            (const char* aName, LogLevel aLevel, int32_t aValue) mutable {
+          if (strcmp(aName, "append") == 0) {
+            shouldAppend = true;
+          } else if (strcmp(aName, "timestamp") == 0) {
+            addTimestamp = true;
+          } else if (strcmp(aName, "sync") == 0) {
+            isSync = true;
+          } else if (strcmp(aName, "rotate") == 0) {
+            rotate = (aValue << 20) / kRotateFilesNumber;
+          } else {
+            LogModule::Get(aName)->SetLevel(aLevel);
+          }
+    });
+
+    // Rotate implies timestamp to make the files readable
+    mAddTimestamp = addTimestamp || rotate > 0;
+    mIsSync = isSync;
+    mRotate = rotate;
+
+    if (rotate > 0 && shouldAppend) {
+      NS_WARNING("MOZ_LOG: when you rotate the log, you cannot use append!");
+    }
+
+    const char* logFile = PR_GetEnv("MOZ_LOG_FILE");
+    if (!logFile || !logFile[0]) {
+      logFile = PR_GetEnv("NSPR_LOG_FILE");
+    }
+
+    if (logFile && logFile[0]) {
+      char buf[2048];
+      logFile = detail::ExpandPIDMarker(logFile, buf);
+      mOutFilePath.reset(strdup(logFile));
+
+      if (mRotate > 0) {
+        // Delete all the previously captured files, including non-rotated
+        // log files, so that users don't complain our logs eat space even
+        // after the rotate option has been added and don't happen to send
+        // us old large logs along with the rotated files.
+        remove(mOutFilePath.get());
+        for (uint32_t i = 0; i < kRotateFilesNumber; ++i) {
+          RemoveFile(i);
+        }
+      }
+
+      mOutFile = OpenFile(shouldAppend, mOutFileNum);
+      mSetFromEnv = true;
+    }
+  }
+
+  void SetLogFile(const char* aFilename)
+  {
+    // For now we don't allow you to change the file at runtime.
+    if (mSetFromEnv) {
+      NS_WARNING("LogModuleManager::SetLogFile - Log file was set from the "
+                 "MOZ_LOG_FILE environment variable.");
+      return;
+    }
+
+    const char * filename = aFilename ? aFilename : "";
+    char buf[2048];
+    filename = detail::ExpandPIDMarker(filename, buf);
+
+    // Can't use rotate at runtime yet.
+    MOZ_ASSERT(mRotate == 0, "We don't allow rotate for runtime logfile changes");
+    mOutFilePath.reset(strdup(filename));
+
+    // Exchange mOutFile and set it to be released once all the writes are done.
+    detail::LogFile* newFile = OpenFile(false, 0);
+    detail::LogFile* oldFile = mOutFile.exchange(newFile);
+
+    // Since we don't allow changing the logfile if MOZ_LOG_FILE is already set,
+    // and we don't allow log rotation when setting it at runtime, mToReleaseFile
+    // will be null, so we're not leaking.
+    DebugOnly<detail::LogFile*> prevFile = mToReleaseFile.exchange(oldFile);
+    MOZ_ASSERT(!prevFile, "Should be null because rotation is not allowed");
+
+    // If we just need to release a file, we must force print, in order to
+    // trigger the closing and release of mToReleaseFile.
+    if (oldFile) {
+      va_list va;
+      empty_va(&va);
+      Print("Logger", LogLevel::Info, "Flushing old log files\n", va);
+    }
+  }
+
+  uint32_t GetLogFile(char *aBuffer, size_t aLength)
+  {
+    uint32_t len = strlen(mOutFilePath.get());
+    if (len + 1 > aLength) {
+      return 0;
+    }
+    snprintf(aBuffer, aLength, "%s", mOutFilePath.get());
+    return len;
+  }
+
+  void SetIsSync(bool aIsSync)
+  {
+    mIsSync = aIsSync;
+  }
+
+  void SetAddTimestamp(bool aAddTimestamp)
+  {
+    mAddTimestamp = aAddTimestamp;
+  }
+
+  detail::LogFile* OpenFile(bool aShouldAppend, uint32_t aFileNum)
+  {
+    FILE* file;
+
+    if (mRotate > 0) {
+      char buf[2048];
+      SprintfLiteral(buf, "%s.%d", mOutFilePath.get(), aFileNum);
+
+      // rotate doesn't support append.
+      file = fopen(buf, "w");
+    } else {
+      file = fopen(mOutFilePath.get(), aShouldAppend ? "a" : "w");
+    }
+
+    if (!file) {
+      return nullptr;
+    }
+
+    return new detail::LogFile(file, aFileNum);
+  }
+
+  void RemoveFile(uint32_t aFileNum)
+  {
+    char buf[2048];
+    SprintfLiteral(buf, "%s.%d", mOutFilePath.get(), aFileNum);
+    remove(buf);
+  }
+
+  LogModule* CreateOrGetModule(const char* aName)
+  {
+    OffTheBooksMutexAutoLock guard(mModulesLock);
+    LogModule* module = nullptr;
+    if (!mModules.Get(aName, &module)) {
+      module = new LogModule(aName, LogLevel::Disabled);
+      mModules.Put(aName, module);
+    }
+
+    return module;
+  }
+
+  void Print(const char* aName, LogLevel aLevel, const char* aFmt, va_list aArgs)
+  {
+    const size_t kBuffSize = 1024;
+    char buff[kBuffSize];
+
+    char* buffToWrite = buff;
+
+    // For backwards compat we need to use the NSPR format string versions
+    // of sprintf and friends and then hand off to printf.
+    va_list argsCopy;
+    va_copy(argsCopy, aArgs);
+    size_t charsWritten = PR_vsnprintf(buff, kBuffSize, aFmt, argsCopy);
+    va_end(argsCopy);
+
+    if (charsWritten == kBuffSize - 1) {
+      // We may have maxed out, allocate a buffer instead.
+      buffToWrite = PR_vsmprintf(aFmt, aArgs);
+      charsWritten = strlen(buffToWrite);
+    }
+
+    // Determine if a newline needs to be appended to the message.
+    const char* newline = "";
+    if (charsWritten == 0 || buffToWrite[charsWritten - 1] != '\n') {
+      newline = "\n";
+    }
+
+    FILE* out = stderr;
+
+    // In case we use rotate, this ensures the FILE is kept alive during
+    // its use.  Increased before we load mOutFile.
+    ++mPrintEntryCount;
+
+    detail::LogFile* outFile = mOutFile;
+    if (outFile) {
+      out = outFile->File();
+    }
+
+    // This differs from the NSPR format in that we do not output the
+    // opaque system specific thread pointer (ie pthread_t) cast
+    // to a long. The address of the current PR_Thread continues to be
+    // prefixed.
+    //
+    // Additionally we prefix the output with the abbreviated log level
+    // and the module name.
+    PRThread *currentThread = PR_GetCurrentThread();
+    const char *currentThreadName = (mMainThread == currentThread)
+      ? "Main Thread"
+      : PR_GetThreadName(currentThread);
+
+    char noNameThread[40];
+    if (!currentThreadName) {
+      SprintfLiteral(noNameThread, "Unnamed thread %p", currentThread);
+      currentThreadName = noNameThread;
+    }
+
+    if (!mAddTimestamp) {
+      fprintf_stderr(out,
+                     "[%s]: %s/%s %s%s",
+                     currentThreadName, ToLogStr(aLevel),
+                     aName, buffToWrite, newline);
+    } else {
+      PRExplodedTime now;
+      PR_ExplodeTime(PR_Now(), PR_GMTParameters, &now);
+      fprintf_stderr(
+          out,
+          "%04d-%02d-%02d %02d:%02d:%02d.%06d UTC - [%s]: %s/%s %s%s",
+          now.tm_year, now.tm_month + 1, now.tm_mday,
+          now.tm_hour, now.tm_min, now.tm_sec, now.tm_usec,
+          currentThreadName, ToLogStr(aLevel),
+          aName, buffToWrite, newline);
+    }
+
+    if (mIsSync) {
+      fflush(out);
+    }
+
+    if (buffToWrite != buff) {
+      PR_smprintf_free(buffToWrite);
+    }
+
+    if (mRotate > 0 && outFile) {
+      int32_t fileSize = ftell(out);
+      if (fileSize > mRotate) {
+        uint32_t fileNum = outFile->Num();
+
+        uint32_t nextFileNum = fileNum + 1;
+        if (nextFileNum >= kRotateFilesNumber) {
+          nextFileNum = 0;
+        }
+
+        // And here is the trick.  The current out-file remembers its order
+        // number.  When no other thread shifted the global file number yet,
+        // we are the thread to open the next file.
+        if (mOutFileNum.compareExchange(fileNum, nextFileNum)) {
+          // We can work with mToReleaseFile because we are sure the
+          // mPrintEntryCount can't drop to zero now - the condition
+          // to actually delete what's stored in that member.
+          // And also, no other thread can enter this piece of code
+          // because mOutFile is still holding the current file with
+          // the non-shifted number.  The compareExchange() above is
+          // a no-op for other threads.
+          outFile->mNextToRelease = mToReleaseFile;
+          mToReleaseFile = outFile;
+
+          mOutFile = OpenFile(false, nextFileNum);
+        }
+      }
+    }
+
+    if (--mPrintEntryCount == 0 && mToReleaseFile) {
+      // We were the last Print() entered, if there is a file to release
+      // do it now.  exchange() is atomic and makes sure we release the file
+      // only once on one thread.
+      detail::LogFile* release = mToReleaseFile.exchange(nullptr);
+      delete release;
+    }
+  }
+
+private:
+  OffTheBooksMutex mModulesLock;
+  nsClassHashtable<nsCharPtrHashKey, LogModule> mModules;
+
+  // Print() entry counter, actually reflects concurrent use of the current
+  // output file.  ReleaseAcquire ensures that manipulation with mOutFile
+  // and mToReleaseFile is synchronized by manipulation with this value.
+  Atomic<uint32_t, ReleaseAcquire> mPrintEntryCount;
+  // File to write to.  ReleaseAcquire because we need to sync mToReleaseFile
+  // with this.
+  Atomic<detail::LogFile*, ReleaseAcquire> mOutFile;
+  // File to be released when reference counter drops to zero.  This member
+  // is assigned mOutFile when the current file has reached the limit.
+  // It can be Relaxed, since it's synchronized with mPrintEntryCount
+  // manipulation and we do atomic exchange() on it.
+  Atomic<detail::LogFile*, Relaxed> mToReleaseFile;
+  // The next file number.  This is mostly only for synchronization sake.
+  // Can have relaxed ordering, since we only do compareExchange on it which
+  // is atomic regardless ordering.
+  Atomic<uint32_t, Relaxed> mOutFileNum;
+  // Just keeps the actual file path for further use.
+  UniqueFreePtr<char[]> mOutFilePath;
+
+  PRThread *mMainThread;
+  bool mSetFromEnv;
+  Atomic<bool, Relaxed> mAddTimestamp;
+  Atomic<bool, Relaxed> mIsSync;
+  int32_t mRotate;
+};
+
+StaticAutoPtr<LogModuleManager> sLogModuleManager;
+
+LogModule*
+LogModule::Get(const char* aName)
+{
+  // This is just a pass through to the LogModuleManager so
+  // that the LogModuleManager implementation can be kept internal.
+  MOZ_ASSERT(sLogModuleManager != nullptr);
+  return sLogModuleManager->CreateOrGetModule(aName);
+}
+
+void
+LogModule::SetLogFile(const char* aFilename)
+{
+  MOZ_ASSERT(sLogModuleManager);
+  sLogModuleManager->SetLogFile(aFilename);
+}
+
+uint32_t
+LogModule::GetLogFile(char *aBuffer, size_t aLength)
+{
+  MOZ_ASSERT(sLogModuleManager);
+  return sLogModuleManager->GetLogFile(aBuffer, aLength);
+}
+
+void
+LogModule::SetAddTimestamp(bool aAddTimestamp)
+{
+  sLogModuleManager->SetAddTimestamp(aAddTimestamp);
+}
+
+void
+LogModule::SetIsSync(bool aIsSync)
+{
+  sLogModuleManager->SetIsSync(aIsSync);
+}
+
+void
+LogModule::Init()
+{
+  // NB: This method is not threadsafe; it is expected to be called very early
+  //     in startup prior to any other threads being run.
+  if (sLogModuleManager) {
+    // Already initialized.
+    return;
+  }
+
+  // NB: We intentionally do not register for ClearOnShutdown as that happens
+  //     before all logging is complete. And, yes, that means we leak, but
+  //     we're doing that intentionally.
+  sLogModuleManager = new LogModuleManager();
+  sLogModuleManager->Init();
+}
+
+void
+LogModule::Printv(LogLevel aLevel, const char* aFmt, va_list aArgs) const
+{
+  MOZ_ASSERT(sLogModuleManager != nullptr);
+
+  // Forward to LogModule manager w/ level and name
+  sLogModuleManager->Print(Name(), aLevel, aFmt, aArgs);
+}
+
+} // namespace mozilla
diff --git a/xpcom/base/Logging.h b/xpcom/base/Logging.h
new file mode 100644
index 000000000..040fb9c49
--- /dev/null
+++ b/xpcom/base/Logging.h
@@ -0,0 +1,255 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_logging_h
+#define mozilla_logging_h
+
+#include <string.h>
+#include <stdarg.h>
+
+#include "prlog.h"
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/Likely.h"
+#include "mozilla/MacroForEach.h"
+
+// This file is a placeholder for a replacement to the NSPR logging framework
+// that is defined in prlog.h. Currently it is just a pass through, but as
+// work progresses more functionality will be swapped out in favor of
+// mozilla logging implementations.
+
+// We normally have logging enabled everywhere, but measurements showed that
+// having logging enabled on Android is quite expensive (hundreds of kilobytes
+// for both the format strings for logging and the code to perform all the
+// logging calls).  Because retrieving logs from a mobile device is
+// comparatively more difficult for Android than it is for desktop and because
+// desktop machines tend to be less space/bandwidth-constrained than Android
+// devices, we've chosen to leave logging enabled on desktop, but disabled on
+// Android.  Given that logging can still be useful for development purposes,
+// however, we leave logging enabled on Android developer builds.
+#if !defined(ANDROID) || !defined(RELEASE_OR_BETA)
+#define MOZ_LOGGING_ENABLED 1
+#else
+#define MOZ_LOGGING_ENABLED 0
+#endif
+
+namespace mozilla {
+
+// While not a 100% mapping to PR_LOG's numeric values, mozilla::LogLevel does
+// maintain a direct mapping for the Disabled, Debug and Verbose levels.
+//
+// Mappings of LogLevel to PR_LOG's numeric values:
+//
+//   +---------+------------------+-----------------+
+//   | Numeric | NSPR Logging     | Mozilla Logging |
+//   +---------+------------------+-----------------+
+//   |       0 | PR_LOG_NONE      | Disabled        |
+//   |       1 | PR_LOG_ALWAYS    | Error           |
+//   |       2 | PR_LOG_ERROR     | Warning         |
+//   |       3 | PR_LOG_WARNING   | Info            |
+//   |       4 | PR_LOG_DEBUG     | Debug           |
+//   |       5 | PR_LOG_DEBUG + 1 | Verbose         |
+//   +---------+------------------+-----------------+
+//
+enum class LogLevel {
+  Disabled = 0,
+  Error,
+  Warning,
+  Info,
+  Debug,
+  Verbose,
+};
+
+/**
+ * Safely converts an integer into a valid LogLevel.
+ */
+LogLevel ToLogLevel(int32_t aLevel);
+
+class LogModule
+{
+public:
+  ~LogModule() { ::free(mName); }
+
+  /**
+   * Retrieves the module with the given name. If it does not already exist
+   * it will be created.
+   *
+   * @param aName The name of the module.
+   * @return A log module for the given name. This may be shared.
+   */
+  static LogModule* Get(const char* aName);
+
+  static void Init();
+
+  /**
+   * Sets the log file to the given filename.
+   */
+  static void SetLogFile(const char* aFilename);
+
+  /**
+   * @param aBuffer - pointer to a buffer
+   * @param aLength - the length of the buffer
+   *
+   * @return the actual length of the filepath.
+   */
+  static uint32_t GetLogFile(char *aBuffer, size_t aLength);
+
+  /**
+   * @param aAddTimestamp If we should log a time stamp with every message.
+   */
+  static void SetAddTimestamp(bool aAddTimestamp);
+
+  /**
+   * @param aIsSync If we should flush the file after every logged message.
+   */
+  static void SetIsSync(bool aIsSync);
+
+  /**
+   * Indicates whether or not the given log level is enabled.
+   */
+  bool ShouldLog(LogLevel aLevel) const { return mLevel >= aLevel; }
+
+  /**
+   * Retrieves the log module's current level.
+   */
+  LogLevel Level() const { return mLevel; }
+
+  /**
+   * Sets the log module's level.
+   */
+  void SetLevel(LogLevel level) { mLevel = level; }
+
+  /**
+   * Print a log message for this module.
+   */
+  void Printv(LogLevel aLevel, const char* aFmt, va_list aArgs) const;
+
+  /**
+   * Retrieves the module name.
+   */
+  const char* Name() const { return mName; }
+
+private:
+  friend class LogModuleManager;
+
+  explicit LogModule(const char* aName, LogLevel aLevel)
+    : mName(strdup(aName)), mLevel(aLevel)
+  {
+  }
+
+  LogModule(LogModule&) = delete;
+  LogModule& operator=(const LogModule&) = delete;
+
+  char* mName;
+  Atomic<LogLevel, Relaxed> mLevel;
+};
+
+/**
+ * Helper class that lazy loads the given log module. This is safe to use for
+ * declaring static references to log modules and can be used as a replacement
+ * for accessing a LogModule directly.
+ *
+ * Example usage:
+ *   static LazyLogModule sLayoutLog("layout");
+ *
+ *   void Foo() {
+ *     MOZ_LOG(sLayoutLog, LogLevel::Verbose, ("Entering foo"));
+ *   }
+ */
+class LazyLogModule final
+{
+public:
+  explicit constexpr LazyLogModule(const char* aLogName)
+    : mLogName(aLogName)
+    , mLog(nullptr)
+  {
+  }
+
+  operator LogModule*()
+  {
+    // NB: The use of an atomic makes the reading and assignment of mLog
+    //     thread-safe. There is a small chance that mLog will be set more
+    //     than once, but that's okay as it will be set to the same LogModule
+    //     instance each time. Also note LogModule::Get is thread-safe.
+    LogModule* tmp = mLog;
+    if (MOZ_UNLIKELY(!tmp)) {
+      tmp = LogModule::Get(mLogName);
+      mLog = tmp;
+    }
+
+    return tmp;
+  }
+
+private:
+  const char* const mLogName;
+  Atomic<LogModule*, ReleaseAcquire> mLog;
+};
+
+namespace detail {
+
+inline bool log_test(const PRLogModuleInfo* module, LogLevel level) {
+  MOZ_ASSERT(level != LogLevel::Disabled);
+  return module && module->level >= static_cast<int>(level);
+}
+
+/**
+ * A rather inefficient wrapper for PR_LogPrint that always allocates.
+ * PR_LogModuleInfo is deprecated so it's not worth the effort to do
+ * any better.
+ */
+void log_print(const PRLogModuleInfo* aModule,
+                      LogLevel aLevel,
+                      const char* aFmt, ...);
+
+inline bool log_test(const LogModule* module, LogLevel level) {
+  MOZ_ASSERT(level != LogLevel::Disabled);
+  return module && module->ShouldLog(level);
+}
+
+void log_print(const LogModule* aModule,
+               LogLevel aLevel,
+               const char* aFmt, ...);
+} // namespace detail
+
+} // namespace mozilla
+
+
+// Helper macro used convert MOZ_LOG's third parameter, |_args|, from a
+// parenthesized form to a varargs form. For example:
+//   ("%s", "a message") => "%s", "a message"
+#define MOZ_LOG_EXPAND_ARGS(...) __VA_ARGS__
+
+#if MOZ_LOGGING_ENABLED
+#define MOZ_LOG_TEST(_module,_level) mozilla::detail::log_test(_module, _level)
+#else
+// Define away MOZ_LOG_TEST here so the compiler will fold away entire
+// logging blocks via dead code elimination, e.g.:
+//
+//   if (MOZ_LOG_TEST(...)) {
+//     ...compute things to log and log them...
+//   }
+//
+// This also has the nice property that no special definition of MOZ_LOG is
+// required when logging is disabled.
+#define MOZ_LOG_TEST(_module,_level) false
+#endif
+
+#define MOZ_LOG(_module,_level,_args)     \
+  PR_BEGIN_MACRO             \
+    if (MOZ_LOG_TEST(_module,_level)) { \
+      mozilla::detail::log_print(_module, _level, MOZ_LOG_EXPAND_ARGS _args);         \
+    }                     \
+  PR_END_MACRO
+
+#undef PR_LOG
+#undef PR_LOG_TEST
+
+// This #define is a Logging.h-only knob!  Don't encourage people to get fancy
+// with their log definitions by exporting it outside of Logging.h.
+#undef MOZ_LOGGING_ENABLED
+
+#endif // mozilla_logging_h
diff --git a/xpcom/base/MacHelpers.h b/xpcom/base/MacHelpers.h
new file mode 100644
index 000000000..9716ae3f2
--- /dev/null
+++ b/xpcom/base/MacHelpers.h
@@ -0,0 +1,18 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_MacHelpers_h
+#define mozilla_MacHelpers_h
+
+#include "nsString.h"
+
+namespace mozilla {
+
+nsresult GetSelectedCityInfo(nsAString& aCountryCode);
+
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/base/MacHelpers.mm b/xpcom/base/MacHelpers.mm
new file mode 100644
index 000000000..19d0d8900
--- /dev/null
+++ b/xpcom/base/MacHelpers.mm
@@ -0,0 +1,41 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsString.h"
+#include "MacHelpers.h"
+#include "nsObjCExceptions.h"
+
+#import <Foundation/Foundation.h>
+
+namespace mozilla {
+
+nsresult
+GetSelectedCityInfo(nsAString& aCountryCode)
+{
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
+
+  // Can be replaced with [[NSLocale currentLocale] countryCode] once we build
+  // with the 10.12 SDK.
+  id countryCode = [[NSLocale currentLocale] objectForKey:NSLocaleCountryCode];
+
+  if (![countryCode isKindOfClass:[NSString class]]) {
+    return NS_ERROR_FAILURE;
+  }
+
+  const char* countryCodeUTF8 = [(NSString*)countryCode UTF8String];
+
+  if (!countryCodeUTF8) {
+    return NS_ERROR_FAILURE;
+  }
+
+  AppendUTF8toUTF16(countryCodeUTF8, aCountryCode);
+  return NS_OK;
+
+  NS_OBJC_END_TRY_ABORT_BLOCK_NSRESULT;
+}
+
+} // namespace Mozilla
+
diff --git a/xpcom/base/NSPRLogModulesParser.cpp b/xpcom/base/NSPRLogModulesParser.cpp
new file mode 100644
index 000000000..21090925c
--- /dev/null
+++ b/xpcom/base/NSPRLogModulesParser.cpp
@@ -0,0 +1,54 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "NSPRLogModulesParser.h"
+
+#include "mozilla/Tokenizer.h"
+
+const char kDelimiters[] = ", ";
+const char kAdditionalWordChars[] = "_-";
+
+namespace mozilla {
+
+void
+NSPRLogModulesParser(const char* aLogModules,
+                     function<void(const char*, LogLevel, int32_t)> aCallback)
+{
+  if (!aLogModules) {
+    return;
+  }
+
+  Tokenizer parser(aLogModules, kDelimiters, kAdditionalWordChars);
+  nsAutoCString moduleName;
+
+  // Format: LOG_MODULES="Foo:2,Bar, Baz:5"
+  while (parser.ReadWord(moduleName)) {
+    // Next should be :<level>, default to Error if not provided.
+    LogLevel logLevel = LogLevel::Error;
+    int32_t levelValue = 0;
+    if (parser.CheckChar(':')) {
+      // Check if a negative value is provided.
+      int32_t multiplier = 1;
+      if (parser.CheckChar([](const char aChar) { return aChar == '-'; })) {
+        multiplier = -1;
+      }
+
+      // NB: If a level isn't provided after the ':' we assume the default
+      //     Error level is desired. This differs from NSPR which will stop
+      //     processing the log module string in this case.
+      if (parser.ReadInteger(&levelValue)) {
+        logLevel = ToLogLevel(levelValue * multiplier);
+      }
+    }
+
+    aCallback(moduleName.get(), logLevel, levelValue);
+
+    // Skip ahead to the next token.
+    parser.SkipWhites();
+  }
+}
+
+} // namespace mozilla
diff --git a/xpcom/base/NSPRLogModulesParser.h b/xpcom/base/NSPRLogModulesParser.h
new file mode 100644
index 000000000..38aab14a3
--- /dev/null
+++ b/xpcom/base/NSPRLogModulesParser.h
@@ -0,0 +1,22 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Logging.h"
+#include "mozilla/Function.h"
+
+namespace mozilla {
+
+/**
+ * Helper function that parses the legacy NSPR_LOG_MODULES env var format
+ * for specifying log levels and logging options.
+ *
+ * @param aLogModules The log modules configuration string.
+ * @param aCallback The callback to invoke for each log module config entry.
+ */
+void NSPRLogModulesParser(const char* aLogModules,
+                          function<void(const char*, LogLevel, int32_t)> aCallback);
+
+} // namespace mozilla
diff --git a/xpcom/base/OwningNonNull.h b/xpcom/base/OwningNonNull.h
new file mode 100644
index 000000000..b72a250c4
--- /dev/null
+++ b/xpcom/base/OwningNonNull.h
@@ -0,0 +1,198 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* A class for non-null strong pointers to reference-counted objects. */
+
+#ifndef mozilla_OwningNonNull_h
+#define mozilla_OwningNonNull_h
+
+#include "nsAutoPtr.h"
+#include "nsCycleCollectionNoteChild.h"
+
+namespace mozilla {
+
+template<class T>
+class OwningNonNull
+{
+public:
+  OwningNonNull() {}
+
+  MOZ_IMPLICIT OwningNonNull(T& aValue)
+  {
+    init(&aValue);
+  }
+
+  template<class U>
+  MOZ_IMPLICIT OwningNonNull(already_AddRefed<U>&& aValue)
+  {
+    init(aValue);
+  }
+
+  template<class U>
+  MOZ_IMPLICIT OwningNonNull(const OwningNonNull<U>& aValue)
+  {
+    init(aValue);
+  }
+
+  // This is no worse than get() in terms of const handling.
+  operator T&() const
+  {
+    MOZ_ASSERT(mInited);
+    MOZ_ASSERT(mPtr, "OwningNonNull<T> was set to null");
+    return *mPtr;
+  }
+
+  operator T*() const
+  {
+    MOZ_ASSERT(mInited);
+    MOZ_ASSERT(mPtr, "OwningNonNull<T> was set to null");
+    return mPtr;
+  }
+
+  // Conversion to bool is always true, so delete to catch errors
+  explicit operator bool() const = delete;
+
+  T*
+  operator->() const
+  {
+    MOZ_ASSERT(mInited);
+    MOZ_ASSERT(mPtr, "OwningNonNull<T> was set to null");
+    return mPtr;
+  }
+
+  OwningNonNull<T>&
+  operator=(T* aValue)
+  {
+    init(aValue);
+    return *this;
+  }
+
+  OwningNonNull<T>&
+  operator=(T& aValue)
+  {
+    init(&aValue);
+    return *this;
+  }
+
+  template<class U>
+  OwningNonNull<T>&
+  operator=(already_AddRefed<U>&& aValue)
+  {
+    init(aValue);
+    return *this;
+  }
+
+  template<class U>
+  OwningNonNull<T>&
+  operator=(const OwningNonNull<U>& aValue)
+  {
+    init(aValue);
+    return *this;
+  }
+
+  // Don't allow assigning nullptr, it makes no sense
+  void operator=(decltype(nullptr)) = delete;
+
+  already_AddRefed<T> forget()
+  {
+#ifdef DEBUG
+    mInited = false;
+#endif
+    return mPtr.forget();
+  }
+
+  template<class U>
+  void
+  forget(U** aOther)
+  {
+#ifdef DEBUG
+    mInited = false;
+#endif
+    mPtr.forget(aOther);
+  }
+
+  // Make us work with smart pointer helpers that expect a get().
+  T* get() const
+  {
+    MOZ_ASSERT(mInited);
+    MOZ_ASSERT(mPtr);
+    return mPtr;
+  }
+
+  template<typename U>
+  void swap(U& aOther)
+  {
+    mPtr.swap(aOther);
+#ifdef DEBUG
+    mInited = mPtr;
+#endif
+  }
+
+  // We have some consumers who want to check whether we're inited in non-debug
+  // builds as well.  Luckily, we have the invariant that we're inited precisely
+  // when mPtr is non-null.
+  bool isInitialized() const
+  {
+    MOZ_ASSERT(!!mPtr == mInited, "mInited out of sync with mPtr?");
+    return mPtr;
+  }
+
+protected:
+  template<typename U>
+  void init(U&& aValue)
+  {
+    mPtr = aValue;
+    MOZ_ASSERT(mPtr);
+#ifdef DEBUG
+    mInited = true;
+#endif
+  }
+
+  RefPtr<T> mPtr;
+#ifdef DEBUG
+  bool mInited = false;
+#endif
+};
+
+template <typename T>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            OwningNonNull<T>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  CycleCollectionNoteChild(aCallback, aField.get(), aName, aFlags);
+}
+
+} // namespace mozilla
+
+// Declared in nsCOMPtr.h
+template<class T> template<class U>
+nsCOMPtr<T>::nsCOMPtr(const mozilla::OwningNonNull<U>& aOther)
+  : nsCOMPtr(aOther.get())
+{}
+
+template<class T> template<class U>
+nsCOMPtr<T>&
+nsCOMPtr<T>::operator=(const mozilla::OwningNonNull<U>& aOther)
+{
+  return operator=(aOther.get());
+}
+
+// Declared in mozilla/RefPtr.h
+template<class T> template<class U>
+RefPtr<T>::RefPtr(const mozilla::OwningNonNull<U>& aOther)
+  : RefPtr(aOther.get())
+{}
+
+template<class T> template<class U>
+RefPtr<T>&
+RefPtr<T>::operator=(const mozilla::OwningNonNull<U>& aOther)
+{
+  return operator=(aOther.get());
+}
+
+#endif // mozilla_OwningNonNull_h
diff --git a/xpcom/base/StaticMutex.h b/xpcom/base/StaticMutex.h
new file mode 100644
index 000000000..731e69405
--- /dev/null
+++ b/xpcom/base/StaticMutex.h
@@ -0,0 +1,96 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_StaticMutex_h
+#define mozilla_StaticMutex_h
+
+#include "mozilla/Atomics.h"
+#include "mozilla/Mutex.h"
+
+namespace mozilla {
+
+/**
+ * StaticMutex is a Mutex that can (and in fact, must) be used as a
+ * global/static variable.
+ *
+ * The main reason to use StaticMutex as opposed to
+ * StaticAutoPtr<OffTheBooksMutex> is that we instantiate the StaticMutex in a
+ * thread-safe manner the first time it's used.
+ *
+ * The same caveats that apply to StaticAutoPtr apply to StaticMutex.  In
+ * particular, do not use StaticMutex as a stack variable or a class instance
+ * variable, because this class relies on the fact that global variablies are
+ * initialized to 0 in order to initialize mMutex.  It is only safe to use
+ * StaticMutex as a global or static variable.
+ */
+class MOZ_ONLY_USED_TO_AVOID_STATIC_CONSTRUCTORS StaticMutex
+{
+public:
+  // In debug builds, check that mMutex is initialized for us as we expect by
+  // the compiler.  In non-debug builds, don't declare a constructor so that
+  // the compiler can see that the constructor is trivial.
+#ifdef DEBUG
+  StaticMutex()
+  {
+    MOZ_ASSERT(!mMutex);
+  }
+#endif
+
+  void Lock()
+  {
+    Mutex()->Lock();
+  }
+
+  void Unlock()
+  {
+    Mutex()->Unlock();
+  }
+
+  void AssertCurrentThreadOwns()
+  {
+#ifdef DEBUG
+    Mutex()->AssertCurrentThreadOwns();
+#endif
+  }
+
+private:
+  OffTheBooksMutex* Mutex()
+  {
+    if (mMutex) {
+      return mMutex;
+    }
+
+    OffTheBooksMutex* mutex = new OffTheBooksMutex("StaticMutex");
+    if (!mMutex.compareExchange(nullptr, mutex)) {
+      delete mutex;
+    }
+
+    return mMutex;
+  }
+
+  Atomic<OffTheBooksMutex*> mMutex;
+
+
+  // Disallow copy constructor, but only in debug mode.  We only define
+  // a default constructor in debug mode (see above); if we declared
+  // this constructor always, the compiler wouldn't generate a trivial
+  // default constructor for us in non-debug mode.
+#ifdef DEBUG
+  StaticMutex(StaticMutex& aOther);
+#endif
+
+  // Disallow these operators.
+  StaticMutex& operator=(StaticMutex* aRhs);
+  static void* operator new(size_t) CPP_THROW_NEW;
+  static void operator delete(void*);
+};
+
+typedef BaseAutoLock<StaticMutex> StaticMutexAutoLock;
+typedef BaseAutoUnlock<StaticMutex> StaticMutexAutoUnlock;
+
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/base/StaticPtr.h b/xpcom/base/StaticPtr.h
new file mode 100644
index 000000000..f2c820a93
--- /dev/null
+++ b/xpcom/base/StaticPtr.h
@@ -0,0 +1,270 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_StaticPtr_h
+#define mozilla_StaticPtr_h
+
+#include "mozilla/AlreadyAddRefed.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/RefPtr.h"
+
+namespace mozilla {
+
+/**
+ * StaticAutoPtr and StaticRefPtr are like nsAutoPtr and nsRefPtr, except they
+ * are suitable for use as global variables.
+ *
+ * In particular, a global instance of Static{Auto,Ref}Ptr doesn't cause the
+ * compiler to emit  a static initializer (in release builds, anyway).
+ *
+ * In order to accomplish this, Static{Auto,Ref}Ptr must have a trivial
+ * constructor and destructor.  As a consequence, it cannot initialize its raw
+ * pointer to 0 on construction, and it cannot delete/release its raw pointer
+ * upon destruction.
+ *
+ * Since the compiler guarantees that all global variables are initialized to
+ * 0, these trivial constructors are safe.  Since we rely on this, the clang
+ * plugin, run as part of our "static analysis" builds, makes it a compile-time
+ * error to use Static{Auto,Ref}Ptr as anything except a global variable.
+ *
+ * Static{Auto,Ref}Ptr have a limited interface as compared to ns{Auto,Ref}Ptr;
+ * this is intentional, since their range of acceptable uses is smaller.
+ */
+
+template<class T>
+class MOZ_ONLY_USED_TO_AVOID_STATIC_CONSTRUCTORS StaticAutoPtr
+{
+public:
+  // In debug builds, check that mRawPtr is initialized for us as we expect
+  // by the compiler.  In non-debug builds, don't declare a constructor
+  // so that the compiler can see that the constructor is trivial.
+#ifdef DEBUG
+  StaticAutoPtr()
+  {
+    MOZ_ASSERT(!mRawPtr);
+  }
+#endif
+
+  StaticAutoPtr<T>& operator=(T* aRhs)
+  {
+    Assign(aRhs);
+    return *this;
+  }
+
+  T* get() const { return mRawPtr; }
+
+  operator T*() const { return get(); }
+
+  T* operator->() const
+  {
+    MOZ_ASSERT(mRawPtr);
+    return get();
+  }
+
+  T& operator*() const { return *get(); }
+
+private:
+  // Disallow copy constructor, but only in debug mode.  We only define
+  // a default constructor in debug mode (see above); if we declared
+  // this constructor always, the compiler wouldn't generate a trivial
+  // default constructor for us in non-debug mode.
+#ifdef DEBUG
+  StaticAutoPtr(StaticAutoPtr<T>& aOther);
+#endif
+
+  void Assign(T* aNewPtr)
+  {
+    MOZ_ASSERT(!aNewPtr || mRawPtr != aNewPtr);
+    T* oldPtr = mRawPtr;
+    mRawPtr = aNewPtr;
+    delete oldPtr;
+  }
+
+  T* mRawPtr;
+};
+
+template<class T>
+class MOZ_ONLY_USED_TO_AVOID_STATIC_CONSTRUCTORS StaticRefPtr
+{
+public:
+  // In debug builds, check that mRawPtr is initialized for us as we expect
+  // by the compiler.  In non-debug builds, don't declare a constructor
+  // so that the compiler can see that the constructor is trivial.
+#ifdef DEBUG
+  StaticRefPtr()
+  {
+    MOZ_ASSERT(!mRawPtr);
+  }
+#endif
+
+  StaticRefPtr<T>& operator=(T* aRhs)
+  {
+    AssignWithAddref(aRhs);
+    return *this;
+  }
+
+  StaticRefPtr<T>& operator=(const StaticRefPtr<T>& aRhs)
+  {
+    return (this = aRhs.mRawPtr);
+  }
+
+  StaticRefPtr<T>& operator=(already_AddRefed<T>& aRhs)
+  {
+    AssignAssumingAddRef(aRhs.take());
+    return *this;
+  }
+
+  StaticRefPtr<T>& operator=(already_AddRefed<T>&& aRhs)
+  {
+    AssignAssumingAddRef(aRhs.take());
+    return *this;
+  }
+
+  already_AddRefed<T>
+  forget()
+  {
+    T* temp = mRawPtr;
+    mRawPtr = nullptr;
+    return already_AddRefed<T>(temp);
+  }
+
+  T* get() const { return mRawPtr; }
+
+  operator T*() const { return get(); }
+
+  T* operator->() const
+  {
+    MOZ_ASSERT(mRawPtr);
+    return get();
+  }
+
+  T& operator*() const { return *get(); }
+
+private:
+  void AssignWithAddref(T* aNewPtr)
+  {
+    if (aNewPtr) {
+      aNewPtr->AddRef();
+    }
+    AssignAssumingAddRef(aNewPtr);
+  }
+
+  void AssignAssumingAddRef(T* aNewPtr)
+  {
+    T* oldPtr = mRawPtr;
+    mRawPtr = aNewPtr;
+    if (oldPtr) {
+      oldPtr->Release();
+    }
+  }
+
+  T* MOZ_OWNING_REF mRawPtr;
+};
+
+namespace StaticPtr_internal {
+class Zero;
+} // namespace StaticPtr_internal
+
+#define REFLEXIVE_EQUALITY_OPERATORS(type1, type2, eq_fn, ...) \
+  template<__VA_ARGS__>                                        \
+  inline bool                                                  \
+  operator==(type1 lhs, type2 rhs)                             \
+  {                                                            \
+    return eq_fn;                                              \
+  }                                                            \
+                                                               \
+  template<__VA_ARGS__>                                        \
+  inline bool                                                  \
+  operator==(type2 lhs, type1 rhs)                             \
+  {                                                            \
+    return rhs == lhs;                                         \
+  }                                                            \
+                                                               \
+  template<__VA_ARGS__>                                        \
+  inline bool                                                  \
+  operator!=(type1 lhs, type2 rhs)                             \
+  {                                                            \
+    return !(lhs == rhs);                                      \
+  }                                                            \
+                                                               \
+  template<__VA_ARGS__>                                        \
+  inline bool                                                  \
+  operator!=(type2 lhs, type1 rhs)                             \
+  {                                                            \
+    return !(lhs == rhs);                                      \
+  }
+
+// StaticAutoPtr (in)equality operators
+
+template<class T, class U>
+inline bool
+operator==(const StaticAutoPtr<T>& aLhs, const StaticAutoPtr<U>& aRhs)
+{
+  return aLhs.get() == aRhs.get();
+}
+
+template<class T, class U>
+inline bool
+operator!=(const StaticAutoPtr<T>& aLhs, const StaticAutoPtr<U>& aRhs)
+{
+  return !(aLhs == aRhs);
+}
+
+REFLEXIVE_EQUALITY_OPERATORS(const StaticAutoPtr<T>&, const U*,
+                             lhs.get() == rhs, class T, class U)
+
+REFLEXIVE_EQUALITY_OPERATORS(const StaticAutoPtr<T>&, U*,
+                             lhs.get() == rhs, class T, class U)
+
+// Let us compare StaticAutoPtr to 0.
+REFLEXIVE_EQUALITY_OPERATORS(const StaticAutoPtr<T>&, StaticPtr_internal::Zero*,
+                             lhs.get() == nullptr, class T)
+
+// StaticRefPtr (in)equality operators
+
+template<class T, class U>
+inline bool
+operator==(const StaticRefPtr<T>& aLhs, const StaticRefPtr<U>& aRhs)
+{
+  return aLhs.get() == aRhs.get();
+}
+
+template<class T, class U>
+inline bool
+operator!=(const StaticRefPtr<T>& aLhs, const StaticRefPtr<U>& aRhs)
+{
+  return !(aLhs == aRhs);
+}
+
+REFLEXIVE_EQUALITY_OPERATORS(const StaticRefPtr<T>&, const U*,
+                             lhs.get() == rhs, class T, class U)
+
+REFLEXIVE_EQUALITY_OPERATORS(const StaticRefPtr<T>&, U*,
+                             lhs.get() == rhs, class T, class U)
+
+// Let us compare StaticRefPtr to 0.
+REFLEXIVE_EQUALITY_OPERATORS(const StaticRefPtr<T>&, StaticPtr_internal::Zero*,
+                             lhs.get() == nullptr, class T)
+
+#undef REFLEXIVE_EQUALITY_OPERATORS
+
+} // namespace mozilla
+
+// Declared in mozilla/RefPtr.h
+template<class T> template<class U>
+RefPtr<T>::RefPtr(const mozilla::StaticRefPtr<U>& aOther)
+  : RefPtr(aOther.get())
+{}
+
+template<class T> template<class U>
+RefPtr<T>&
+RefPtr<T>::operator=(const mozilla::StaticRefPtr<U>& aOther)
+{
+  return operator=(aOther.get());
+}
+
+#endif
diff --git a/xpcom/base/SystemMemoryReporter.cpp b/xpcom/base/SystemMemoryReporter.cpp
new file mode 100644
index 000000000..105b9c8cf
--- /dev/null
+++ b/xpcom/base/SystemMemoryReporter.cpp
@@ -0,0 +1,989 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/SystemMemoryReporter.h"
+
+#include "mozilla/Attributes.h"
+#include "mozilla/LinuxUtils.h"
+#include "mozilla/PodOperations.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/TaggedAnonymousMemory.h"
+#include "mozilla/Unused.h"
+
+#include "nsDataHashtable.h"
+#include "nsIMemoryReporter.h"
+#include "nsPrintfCString.h"
+#include "nsString.h"
+#include "nsTHashtable.h"
+#include "nsHashKeys.h"
+
+#include <dirent.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <errno.h>
+
+// This file implements a Linux-specific, system-wide memory reporter.  It
+// gathers all the useful memory measurements obtainable from the OS in a
+// single place, giving a high-level view of memory consumption for the entire
+// machine/device.
+//
+// Other memory reporters measure part of a single process's memory consumption.
+// This reporter is different in that it measures memory consumption of many
+// processes, and they end up in a single reports tree.  This is a slight abuse
+// of the memory reporting infrastructure, and therefore the results are given
+// their own "process" called "System", which means they show up in about:memory
+// in their own section, distinct from the per-process sections.
+
+namespace mozilla {
+namespace SystemMemoryReporter {
+
+#if !defined(XP_LINUX)
+#error "This won't work if we're not on Linux."
+#endif
+
+/**
+ * RAII helper that will close an open DIR handle.
+ */
+struct MOZ_STACK_CLASS AutoDir
+{
+  explicit AutoDir(DIR* aDir) : mDir(aDir) {}
+  ~AutoDir() { if (mDir) closedir(mDir); };
+  DIR* mDir;
+};
+
+/**
+ * RAII helper that will close an open FILE handle.
+ */
+struct MOZ_STACK_CLASS AutoFile
+{
+  explicit AutoFile(FILE* aFile) : mFile(aFile) {}
+  ~AutoFile() { if (mFile) fclose(mFile); }
+  FILE* mFile;
+};
+
+static bool
+EndsWithLiteral(const nsCString& aHaystack, const char* aNeedle)
+{
+  int32_t idx = aHaystack.RFind(aNeedle);
+  return idx != -1 && idx + strlen(aNeedle) == aHaystack.Length();
+}
+
+static void
+GetDirname(const nsCString& aPath, nsACString& aOut)
+{
+  int32_t idx = aPath.RFind("/");
+  if (idx == -1) {
+    aOut.Truncate();
+  } else {
+    aOut.Assign(Substring(aPath, 0, idx));
+  }
+}
+
+static void
+GetBasename(const nsCString& aPath, nsACString& aOut)
+{
+  nsCString out;
+  int32_t idx = aPath.RFind("/");
+  if (idx == -1) {
+    out.Assign(aPath);
+  } else {
+    out.Assign(Substring(aPath, idx + 1));
+  }
+
+  // On Android, some entries in /dev/ashmem end with "(deleted)" (e.g.
+  // "/dev/ashmem/libxul.so(deleted)").  We don't care about this modifier, so
+  // cut it off when getting the entry's basename.
+  if (EndsWithLiteral(out, "(deleted)")) {
+    out.Assign(Substring(out, 0, out.RFind("(deleted)")));
+  }
+  out.StripChars(" ");
+
+  aOut.Assign(out);
+}
+
+static bool
+IsNumeric(const char* aStr)
+{
+  MOZ_ASSERT(*aStr);  // shouldn't see empty strings
+  while (*aStr) {
+    if (!isdigit(*aStr)) {
+      return false;
+    }
+    ++aStr;
+  }
+  return true;
+}
+
+static bool
+IsAnonymous(const nsACString& aName)
+{
+  // Recent kernels have multiple [stack:nnnn] entries, where |nnnn| is a
+  // thread ID.  However, the entire virtual memory area containing a thread's
+  // stack pointer is considered the stack for that thread, even if it was
+  // merged with an adjacent area containing non-stack data.  So we treat them
+  // as regular anonymous memory.  However, see below about tagged anonymous
+  // memory.
+  return aName.IsEmpty() ||
+         StringBeginsWith(aName, NS_LITERAL_CSTRING("[stack:"));
+}
+
+class SystemReporter final : public nsIMemoryReporter
+{
+  ~SystemReporter() {}
+
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+#define REPORT(_path, _units, _amount, _desc)                                 \
+  do {                                                                        \
+    size_t __amount = _amount;  /* evaluate _amount only once */              \
+    if (__amount > 0) {                                                       \
+      aHandleReport->Callback(NS_LITERAL_CSTRING("System"), _path,            \
+                              KIND_OTHER, _units, __amount, _desc, aData);    \
+    }                                                                         \
+  } while (0)
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override
+  {
+    // There is lots of privacy-sensitive data in /proc. Just skip this
+    // reporter entirely when anonymization is required.
+    if (aAnonymize) {
+      return NS_OK;
+    }
+
+    if (!Preferences::GetBool("memory.system_memory_reporter")) {
+      return NS_OK;
+    }
+
+    // Read relevant fields from /proc/meminfo.
+    int64_t memTotal = 0, memFree = 0;
+    nsresult rv1 = ReadMemInfo(&memTotal, &memFree);
+
+    // Collect per-process reports from /proc/<pid>/smaps.
+    int64_t totalPss = 0;
+    nsresult rv2 = CollectProcessReports(aHandleReport, aData, &totalPss);
+
+    // Report the non-process numbers.
+    if (NS_SUCCEEDED(rv1) && NS_SUCCEEDED(rv2)) {
+      int64_t other = memTotal - memFree - totalPss;
+      REPORT(NS_LITERAL_CSTRING("mem/other"), UNITS_BYTES, other,
+             NS_LITERAL_CSTRING(
+"Memory which is neither owned by any user-space process nor free. Note that "
+"this includes memory holding cached files from the disk which can be "
+"reclaimed by the OS at any time."));
+
+      REPORT(NS_LITERAL_CSTRING("mem/free"), UNITS_BYTES, memFree,
+             NS_LITERAL_CSTRING(
+"Memory which is free and not being used for any purpose."));
+    }
+
+    // Report reserved memory not included in memTotal.
+    CollectPmemReports(aHandleReport, aData);
+
+    // Report zram usage statistics.
+    CollectZramReports(aHandleReport, aData);
+
+    // Report kgsl graphics memory usage.
+    CollectKgslReports(aHandleReport, aData);
+
+    // Report ION memory usage.
+    CollectIonReports(aHandleReport, aData);
+
+    return NS_OK;
+  }
+
+private:
+  // These are the cross-cutting measurements across all processes.
+  class ProcessSizes
+  {
+  public:
+    void Add(const nsACString& aKey, size_t aSize)
+    {
+      mTagged.Put(aKey, mTagged.Get(aKey) + aSize);
+    }
+
+    void Report(nsIHandleReportCallback* aHandleReport, nsISupports* aData)
+    {
+      for (auto iter = mTagged.Iter(); !iter.Done(); iter.Next()) {
+        nsCStringHashKey::KeyType key = iter.Key();
+        size_t amount = iter.UserData();
+
+        nsAutoCString path("processes/");
+        path.Append(key);
+
+        nsAutoCString desc("This is the sum of all processes' '");
+        desc.Append(key);
+        desc.AppendLiteral("' numbers.");
+
+        REPORT(path, UNITS_BYTES, amount, desc);
+      }
+    }
+
+  private:
+    nsDataHashtable<nsCStringHashKey, size_t> mTagged;
+  };
+
+  nsresult ReadMemInfo(int64_t* aMemTotal, int64_t* aMemFree)
+  {
+    FILE* f = fopen("/proc/meminfo", "r");
+    if (!f) {
+      return NS_ERROR_FAILURE;
+    }
+
+    int n1 = fscanf(f, "MemTotal: %" SCNd64 " kB\n", aMemTotal);
+    int n2 = fscanf(f, "MemFree: %"  SCNd64 " kB\n", aMemFree);
+
+    fclose(f);
+
+    if (n1 != 1 || n2 != 1) {
+      return NS_ERROR_FAILURE;
+    }
+
+    // Convert from KB to B.
+    *aMemTotal *= 1024;
+    *aMemFree  *= 1024;
+
+    return NS_OK;
+  }
+
+  nsresult CollectProcessReports(nsIHandleReportCallback* aHandleReport,
+                                 nsISupports* aData,
+                                 int64_t* aTotalPss)
+  {
+    *aTotalPss = 0;
+    ProcessSizes processSizes;
+
+    DIR* d = opendir("/proc");
+    if (NS_WARN_IF(!d)) {
+      return NS_ERROR_FAILURE;
+    }
+    struct dirent* ent;
+    while ((ent = readdir(d))) {
+      struct stat statbuf;
+      const char* pidStr = ent->d_name;
+      // Don't check the return value of stat() -- it can return -1 for these
+      // directories even when it has succeeded, apparently.
+      stat(pidStr, &statbuf);
+      if (S_ISDIR(statbuf.st_mode) && IsNumeric(pidStr)) {
+        nsCString processName("process(");
+
+        // Get the command name from cmdline.  If that fails, the pid is still
+        // shown.
+        nsPrintfCString cmdlinePath("/proc/%s/cmdline", pidStr);
+        FILE* f = fopen(cmdlinePath.get(), "r");
+        if (f) {
+          static const size_t len = 256;
+          char buf[len];
+          if (fgets(buf, len, f)) {
+            processName.Append(buf);
+            // A hack: replace forward slashes with '\\' so they aren't treated
+            // as path separators.  Consumers of this reporter (such as
+            // about:memory) have to undo this change.
+            processName.ReplaceChar('/', '\\');
+            processName.AppendLiteral(", ");
+          }
+          fclose(f);
+        }
+        processName.AppendLiteral("pid=");
+        processName.Append(pidStr);
+        processName.Append(')');
+
+        // Read the PSS values from the smaps file.
+        nsPrintfCString smapsPath("/proc/%s/smaps", pidStr);
+        f = fopen(smapsPath.get(), "r");
+        if (!f) {
+          // Processes can terminate between the readdir() call above and now,
+          // so just skip if we can't open the file.
+          continue;
+        }
+        ParseMappings(f, processName, aHandleReport, aData, &processSizes,
+                      aTotalPss);
+        fclose(f);
+
+        // Report the open file descriptors for this process.
+        nsPrintfCString procFdPath("/proc/%s/fd", pidStr);
+        CollectOpenFileReports(aHandleReport, aData, procFdPath, processName);
+      }
+    }
+    closedir(d);
+
+    // Report the "processes/" tree.
+    processSizes.Report(aHandleReport, aData);
+
+    return NS_OK;
+  }
+
+  void ParseMappings(FILE* aFile,
+                     const nsACString& aProcessName,
+                     nsIHandleReportCallback* aHandleReport,
+                     nsISupports* aData,
+                     ProcessSizes* aProcessSizes,
+                     int64_t* aTotalPss)
+  {
+    // The first line of an entry in /proc/<pid>/smaps looks just like an entry
+    // in /proc/<pid>/maps:
+    //
+    //   address           perms offset  dev   inode  pathname
+    //   02366000-025d8000 rw-p 00000000 00:00 0      [heap]
+    //
+    // Each of the following lines contains a key and a value, separated
+    // by ": ", where the key does not contain either of those characters.
+    // Assuming more than this about the structure of those lines has
+    // failed to be future-proof in the past, so we avoid doing so.
+    //
+    // This makes it difficult to detect the start of a new entry
+    // until it's been removed from the stdio buffer, so we just loop
+    // over all lines in the file in this routine.
+
+    const int argCount = 8;
+
+    unsigned long long addrStart, addrEnd;
+    char perms[5];
+    unsigned long long offset;
+    // The 2.6 and 3.0 kernels allocate 12 bits for the major device number and
+    // 20 bits for the minor device number.  Future kernels might allocate more.
+    // 64 bits ought to be enough for anybody.
+    char devMajor[17];
+    char devMinor[17];
+    unsigned int inode;
+    char line[1025];
+
+    // This variable holds the path of the current entry, or is void
+    // if we're scanning for the start of a new entry.
+    nsAutoCString currentPath;
+    int pathOffset;
+
+    currentPath.SetIsVoid(true);
+    while (fgets(line, sizeof(line), aFile)) {
+      if (currentPath.IsVoid()) {
+        int n = sscanf(line,
+                       "%llx-%llx %4s %llx "
+                       "%16[0-9a-fA-F]:%16[0-9a-fA-F] %u %n",
+                       &addrStart, &addrEnd, perms, &offset, devMajor,
+                       devMinor, &inode, &pathOffset);
+
+        if (n >= argCount - 1) {
+          currentPath.Assign(line + pathOffset);
+          currentPath.StripChars("\n");
+        }
+        continue;
+      }
+
+      // Now that we have a name and other metadata, scan for the PSS.
+      size_t pss_kb;
+      int n = sscanf(line, "Pss: %zu", &pss_kb);
+      if (n < 1) {
+        continue;
+      }
+
+      size_t pss = pss_kb * 1024;
+      if (pss > 0) {
+        nsAutoCString name, description, tag;
+        GetReporterNameAndDescription(currentPath.get(), perms, name, description, tag);
+
+        nsAutoCString processMemPath("mem/processes/");
+        processMemPath.Append(aProcessName);
+        processMemPath.Append('/');
+        processMemPath.Append(name);
+
+        REPORT(processMemPath, UNITS_BYTES, pss, description);
+
+        // Increment the appropriate aProcessSizes values, and the total.
+        aProcessSizes->Add(tag, pss);
+        *aTotalPss += pss;
+      }
+
+      // Now that we've seen the PSS, we're done with this entry.
+      currentPath.SetIsVoid(true);
+    }
+  }
+
+  void GetReporterNameAndDescription(const char* aPath,
+                                     const char* aPerms,
+                                     nsACString& aName,
+                                     nsACString& aDesc,
+                                     nsACString& aTag)
+  {
+    aName.Truncate();
+    aDesc.Truncate();
+    aTag.Truncate();
+
+    // If aPath points to a file, we have its absolute path; it might
+    // also be a bracketed pseudo-name (see below).  In either case
+    // there is also some whitespace to trim.
+    nsAutoCString absPath;
+    absPath.Append(aPath);
+    absPath.StripChars(" ");
+
+    if (absPath.EqualsLiteral("[heap]")) {
+      aName.AppendLiteral("anonymous/brk-heap");
+      aDesc.AppendLiteral(
+        "Memory in anonymous mappings within the boundaries defined by "
+        "brk() / sbrk().  This is likely to be just a portion of the "
+        "application's heap; the remainder lives in other anonymous mappings. "
+        "This corresponds to '[heap]' in /proc/<pid>/smaps.");
+      aTag = aName;
+    } else if (absPath.EqualsLiteral("[stack]")) {
+      aName.AppendLiteral("stack/main-thread");
+      aDesc.AppendPrintf(
+        "The stack size of the process's main thread.  This corresponds to "
+        "'[stack]' in /proc/<pid>/smaps.");
+      aTag = aName;
+    } else if (MozTaggedMemoryIsSupported() &&
+               StringBeginsWith(absPath, NS_LITERAL_CSTRING("[stack:"))) {
+      // If tagged memory is supported, we can be reasonably sure that
+      // the virtual memory area containing the stack hasn't been
+      // merged with unrelated heap memory.  (This prevents the
+      // "[stack:" entries from reaching the IsAnonymous case below.)
+      pid_t tid = atoi(absPath.get() + 7);
+      nsAutoCString threadName, escapedThreadName;
+      LinuxUtils::GetThreadName(tid, threadName);
+      if (threadName.IsEmpty()) {
+        threadName.AssignLiteral("<unknown>");
+      }
+      escapedThreadName.Assign(threadName);
+      escapedThreadName.StripChars("()");
+      escapedThreadName.ReplaceChar('/', '\\');
+
+      aName.AppendLiteral("stack/non-main-thread");
+      aName.AppendLiteral("/name(");
+      aName.Append(escapedThreadName);
+      aName.Append(')');
+      aTag = aName;
+      aName.AppendPrintf("/thread(%d)", tid);
+
+      aDesc.AppendPrintf("The stack size of a non-main thread named '%s' with "
+                         "thread ID %d.  This corresponds to '[stack:%d]' "
+                         "in /proc/%d/smaps.", threadName.get(), tid, tid);
+    } else if (absPath.EqualsLiteral("[vdso]")) {
+      aName.AppendLiteral("vdso");
+      aDesc.AppendLiteral(
+        "The virtual dynamically-linked shared object, also known as the "
+        "'vsyscall page'. This is a memory region mapped by the operating "
+        "system for the purpose of allowing processes to perform some "
+        "privileged actions without the overhead of a syscall.");
+      aTag = aName;
+    } else if (StringBeginsWith(absPath, NS_LITERAL_CSTRING("[anon:")) &&
+               EndsWithLiteral(absPath, "]")) {
+      // It's tagged memory; see also "mfbt/TaggedAnonymousMemory.h".
+      nsAutoCString tag(Substring(absPath, 6, absPath.Length() - 7));
+
+      aName.AppendLiteral("anonymous/");
+      aName.Append(tag);
+      aTag = aName;
+      aDesc.AppendLiteral("Memory in anonymous mappings tagged with '");
+      aDesc.Append(tag);
+      aDesc.Append('\'');
+    } else if (!IsAnonymous(absPath)) {
+      // We now know it's an actual file.  Truncate this to its
+      // basename, and put the absolute path in the description.
+      nsAutoCString basename, dirname;
+      GetBasename(absPath, basename);
+      GetDirname(absPath, dirname);
+
+      // Hack: A file is a shared library if the basename contains ".so" and
+      // its dirname contains "/lib", or if the basename ends with ".so".
+      if (EndsWithLiteral(basename, ".so") ||
+          (basename.Find(".so") != -1 && dirname.Find("/lib") != -1)) {
+        aName.AppendLiteral("shared-libraries/");
+        aTag = aName;
+
+        if (strncmp(aPerms, "r-x", 3) == 0) {
+          aTag.AppendLiteral("read-executable");
+        } else if (strncmp(aPerms, "rw-", 3) == 0) {
+          aTag.AppendLiteral("read-write");
+        } else if (strncmp(aPerms, "r--", 3) == 0) {
+          aTag.AppendLiteral("read-only");
+        } else {
+          aTag.AppendLiteral("other");
+        }
+
+      } else {
+        aName.AppendLiteral("other-files");
+        if (EndsWithLiteral(basename, ".xpi")) {
+          aName.AppendLiteral("/extensions");
+        } else if (dirname.Find("/fontconfig") != -1) {
+          aName.AppendLiteral("/fontconfig");
+        } else {
+          aName.AppendLiteral("/misc");
+        }
+        aTag = aName;
+        aName.Append('/');
+      }
+
+      aName.Append(basename);
+      aDesc.Append(absPath);
+    } else {
+      if (MozTaggedMemoryIsSupported()) {
+        aName.AppendLiteral("anonymous/untagged");
+        aDesc.AppendLiteral("Memory in untagged anonymous mappings.");
+        aTag = aName;
+      } else {
+        aName.AppendLiteral("anonymous/outside-brk");
+        aDesc.AppendLiteral("Memory in anonymous mappings outside the "
+                            "boundaries defined by brk() / sbrk().");
+        aTag = aName;
+      }
+    }
+
+    aName.AppendLiteral("/[");
+    aName.Append(aPerms);
+    aName.Append(']');
+
+    // Append the permissions.  This is useful for non-verbose mode in
+    // about:memory when the filename is long and goes of the right side of the
+    // window.
+    aDesc.AppendLiteral(" [");
+    aDesc.Append(aPerms);
+    aDesc.Append(']');
+  }
+
+  void CollectPmemReports(nsIHandleReportCallback* aHandleReport,
+                          nsISupports* aData)
+  {
+    // The pmem subsystem allocates physically contiguous memory for
+    // interfacing with hardware.  In order to ensure availability,
+    // this memory is reserved during boot, and allocations are made
+    // within these regions at runtime.
+    //
+    // There are typically several of these pools allocated at boot.
+    // The /sys/kernel/pmem_regions directory contains a subdirectory
+    // for each one.  Within each subdirectory, the files we care
+    // about are "size" (the total amount of physical memory) and
+    // "mapped_regions" (a list of the current allocations within that
+    // area).
+    DIR* d = opendir("/sys/kernel/pmem_regions");
+    if (!d) {
+      return;
+    }
+
+    struct dirent* ent;
+    while ((ent = readdir(d))) {
+      const char* name = ent->d_name;
+      uint64_t size;
+      int scanned;
+
+      // Skip "." and ".." (and any other dotfiles).
+      if (name[0] == '.') {
+        continue;
+      }
+
+      // Read the total size.  The file gives the size in decimal and
+      // hex, in the form "13631488(0xd00000)"; we parse the former.
+      nsPrintfCString sizePath("/sys/kernel/pmem_regions/%s/size", name);
+      FILE* sizeFile = fopen(sizePath.get(), "r");
+      if (NS_WARN_IF(!sizeFile)) {
+        continue;
+      }
+      scanned = fscanf(sizeFile, "%" SCNu64, &size);
+      fclose(sizeFile);
+      if (NS_WARN_IF(scanned != 1)) {
+        continue;
+      }
+
+      // Read mapped regions; format described below.
+      uint64_t freeSize = size;
+      nsPrintfCString regionsPath("/sys/kernel/pmem_regions/%s/mapped_regions",
+                                  name);
+      FILE* regionsFile = fopen(regionsPath.get(), "r");
+      if (regionsFile) {
+        static const size_t bufLen = 4096;
+        char buf[bufLen];
+        while (fgets(buf, bufLen, regionsFile)) {
+          int pid;
+
+          // Skip header line.
+          if (strncmp(buf, "pid #", 5) == 0) {
+            continue;
+          }
+          // Line format: "pid N:" + zero or more "(Start,Len) ".
+          // N is decimal; Start and Len are in hex.
+          scanned = sscanf(buf, "pid %d", &pid);
+          if (NS_WARN_IF(scanned != 1)) {
+            continue;
+          }
+          for (const char* nextParen = strchr(buf, '(');
+               nextParen != nullptr;
+               nextParen = strchr(nextParen + 1, '(')) {
+            uint64_t mapStart, mapLen;
+
+            scanned = sscanf(nextParen + 1, "%" SCNx64 ",%" SCNx64,
+                             &mapStart, &mapLen);
+            if (NS_WARN_IF(scanned != 2)) {
+              break;
+            }
+
+            nsPrintfCString path("mem/pmem/used/%s/segment(pid=%d, "
+                                 "offset=0x%" PRIx64 ")", name, pid, mapStart);
+            nsPrintfCString desc("Physical memory reserved for the \"%s\" pool "
+                                 "and allocated to a buffer.", name);
+            REPORT(path, UNITS_BYTES, mapLen, desc);
+            freeSize -= mapLen;
+          }
+        }
+        fclose(regionsFile);
+      }
+
+      nsPrintfCString path("mem/pmem/free/%s", name);
+      nsPrintfCString desc("Physical memory reserved for the \"%s\" pool and "
+                           "unavailable to the rest of the system, but not "
+                           "currently allocated.", name);
+      REPORT(path, UNITS_BYTES, freeSize, desc);
+    }
+    closedir(d);
+  }
+
+  void
+  CollectIonReports(nsIHandleReportCallback* aHandleReport,
+                    nsISupports* aData)
+  {
+    // ION is a replacement for PMEM (and other similar allocators).
+    //
+    // More details from http://lwn.net/Articles/480055/
+    //  "Like its PMEM-like predecessors, ION manages one or more memory pools,
+    //   some of which are set aside at boot time to combat fragmentation or to
+    //   serve special hardware needs. GPUs, display controllers, and cameras
+    //   are some of the hardware blocks that may have special memory
+    //   requirements."
+    //
+    // The file format starts as follows:
+    //     client              pid             size
+    //     ----------------------------------------------------
+    //     adsprpc-smd                1             4096
+    //     fd900000.qcom,mdss_mdp     1          1658880
+    //     ----------------------------------------------------
+    //     orphaned allocations (info is from last known client):
+    //     Homescreen            24100           294912 0 1
+    //     b2g                   23987          1658880 0 1
+    //     mdss_fb0                401          1658880 0 1
+    //     b2g                   23987             4096 0 1
+    //     Built-in Keyboa       24205            61440 0 1
+    //     ----------------------------------------------------
+    //     <other stuff>
+    //
+    // For our purposes we only care about the first portion of the file noted
+    // above which contains memory alloations (both sections). The term
+    // "orphaned" is misleading, it appears that every allocation not by the
+    // first process is considered orphaned on FxOS devices.
+
+    // The first three fields of each entry interest us:
+    //   1) client - Essentially the process name. We limit client names to 63
+    //               characters, in theory they should never be greater than 15
+    //               due to thread name length limitations.
+    //   2) pid    - The ID of the allocating process, read as a uint32_t.
+    //   3) size   - The size of the allocation in bytes, read as as a uint64_t.
+    const char* const kFormatString = "%63s %" SCNu32 " %" SCNu64;
+    const int kNumFields = 3;
+    const size_t kStringSize = 64;
+    const char* const kIonIommuPath = "/sys/kernel/debug/ion/iommu";
+
+    FILE* iommu = fopen(kIonIommuPath, "r");
+    if (!iommu) {
+      return;
+    }
+
+    AutoFile iommuGuard(iommu);
+
+    const size_t kBufferLen = 256;
+    char buffer[kBufferLen];
+    char client[kStringSize];
+    uint32_t pid;
+    uint64_t size;
+
+    // Ignore the header line.
+    Unused << fgets(buffer, kBufferLen, iommu);
+
+    // Ignore the separator line.
+    Unused << fgets(buffer, kBufferLen, iommu);
+
+    const char* const kSep = "----";
+    const size_t kSepLen = 4;
+
+    // Read non-orphaned entries.
+    while (fgets(buffer, kBufferLen, iommu) &&
+           strncmp(kSep, buffer, kSepLen) != 0) {
+      if (sscanf(buffer, kFormatString, client, &pid, &size) == kNumFields) {
+        nsPrintfCString entryPath("ion-memory/%s (pid=%d)", client, pid);
+        REPORT(entryPath, UNITS_BYTES, size,
+               NS_LITERAL_CSTRING("An ION kernel memory allocation."));
+      }
+    }
+
+    // Ignore the orphaned header.
+    Unused << fgets(buffer, kBufferLen, iommu);
+
+    // Read orphaned entries.
+    while (fgets(buffer, kBufferLen, iommu) &&
+           strncmp(kSep, buffer, kSepLen) != 0) {
+      if (sscanf(buffer, kFormatString, client, &pid, &size) == kNumFields) {
+        nsPrintfCString entryPath("ion-memory/%s (pid=%d)", client, pid);
+        REPORT(entryPath, UNITS_BYTES, size,
+               NS_LITERAL_CSTRING("An ION kernel memory allocation."));
+      }
+    }
+
+    // Ignore the rest of the file.
+  }
+
+  uint64_t
+  ReadSizeFromFile(const char* aFilename)
+  {
+    FILE* sizeFile = fopen(aFilename, "r");
+    if (NS_WARN_IF(!sizeFile)) {
+      return 0;
+    }
+
+    uint64_t size = 0;
+    Unused << fscanf(sizeFile, "%" SCNu64, &size);
+    fclose(sizeFile);
+
+    return size;
+  }
+
+  void
+  CollectZramReports(nsIHandleReportCallback* aHandleReport,
+                     nsISupports* aData)
+  {
+    // zram usage stats files can be found under:
+    //  /sys/block/zram<id>
+    //  |--> disksize        - Maximum amount of uncompressed data that can be
+    //                         stored on the disk (bytes)
+    //  |--> orig_data_size  - Uncompressed size of data in the disk (bytes)
+    //  |--> compr_data_size - Compressed size of the data in the disk (bytes)
+    //  |--> num_reads       - Number of attempted reads to the disk (count)
+    //  |--> num_writes      - Number of attempted writes to the disk (count)
+    //
+    // Each file contains a single integer value in decimal form.
+
+    DIR* d = opendir("/sys/block");
+    if (!d) {
+      return;
+    }
+
+    struct dirent* ent;
+    while ((ent = readdir(d))) {
+      const char* name = ent->d_name;
+
+      // Skip non-zram entries.
+      if (strncmp("zram", name, 4) != 0) {
+        continue;
+      }
+
+      // Report disk size statistics.
+      nsPrintfCString diskSizeFile("/sys/block/%s/disksize", name);
+      nsPrintfCString origSizeFile("/sys/block/%s/orig_data_size", name);
+
+      uint64_t diskSize = ReadSizeFromFile(diskSizeFile.get());
+      uint64_t origSize = ReadSizeFromFile(origSizeFile.get());
+      uint64_t unusedSize = diskSize - origSize;
+
+      nsPrintfCString diskUsedPath("zram-disksize/%s/used", name);
+      nsPrintfCString diskUsedDesc(
+        "The uncompressed size of data stored in \"%s.\" "
+        "This excludes zero-filled pages since "
+        "no memory is allocated for them.", name);
+      REPORT(diskUsedPath, UNITS_BYTES, origSize, diskUsedDesc);
+
+      nsPrintfCString diskUnusedPath("zram-disksize/%s/unused", name);
+      nsPrintfCString diskUnusedDesc(
+        "The amount of uncompressed data that can still be "
+        "be stored in \"%s\"", name);
+      REPORT(diskUnusedPath, UNITS_BYTES, unusedSize, diskUnusedDesc);
+
+      // Report disk accesses.
+      nsPrintfCString readsFile("/sys/block/%s/num_reads", name);
+      nsPrintfCString writesFile("/sys/block/%s/num_writes", name);
+
+      uint64_t reads = ReadSizeFromFile(readsFile.get());
+      uint64_t writes = ReadSizeFromFile(writesFile.get());
+
+      nsPrintfCString readsDesc(
+        "The number of reads (failed or successful) done on "
+        "\"%s\"", name);
+      nsPrintfCString readsPath("zram-accesses/%s/reads", name);
+      REPORT(readsPath, UNITS_COUNT_CUMULATIVE, reads, readsDesc);
+
+      nsPrintfCString writesDesc(
+        "The number of writes (failed or successful) done "
+        "on \"%s\"", name);
+      nsPrintfCString writesPath("zram-accesses/%s/writes", name);
+      REPORT(writesPath, UNITS_COUNT_CUMULATIVE, writes, writesDesc);
+
+      // Report compressed data size.
+      nsPrintfCString comprSizeFile("/sys/block/%s/compr_data_size", name);
+      uint64_t comprSize = ReadSizeFromFile(comprSizeFile.get());
+
+      nsPrintfCString comprSizeDesc(
+        "The compressed size of data stored in \"%s\"",
+        name);
+      nsPrintfCString comprSizePath("zram-compr-data-size/%s", name);
+      REPORT(comprSizePath, UNITS_BYTES, comprSize, comprSizeDesc);
+    }
+
+    closedir(d);
+  }
+
+  void
+  CollectOpenFileReports(nsIHandleReportCallback* aHandleReport,
+                         nsISupports* aData,
+                         const nsACString& aProcPath,
+                         const nsACString& aProcessName)
+  {
+    // All file descriptors opened by a process are listed under
+    // /proc/<pid>/fd/<numerical_fd>. Each entry is a symlink that points to the
+    // path that was opened. This can be an actual file, a socket, a pipe, an
+    // anon_inode, or possibly an uncategorized device.
+    const char kFilePrefix[] = "/";
+    const char kSocketPrefix[] = "socket:";
+    const char kPipePrefix[] = "pipe:";
+    const char kAnonInodePrefix[] = "anon_inode:";
+
+    const nsCString procPath(aProcPath);
+    DIR* d = opendir(procPath.get());
+    if (!d) {
+      return;
+    }
+
+    char linkPath[PATH_MAX + 1];
+    struct dirent* ent;
+    while ((ent = readdir(d))) {
+      const char* fd = ent->d_name;
+
+      // Skip "." and ".." (and any other dotfiles).
+      if (fd[0] == '.') {
+        continue;
+      }
+
+      nsPrintfCString fullPath("%s/%s", procPath.get(), fd);
+      ssize_t linkPathSize = readlink(fullPath.get(), linkPath, PATH_MAX);
+      if (linkPathSize > 0) {
+        linkPath[linkPathSize] = '\0';
+
+#define CHECK_PREFIX(prefix) \
+  (strncmp(linkPath, prefix, sizeof(prefix) - 1) == 0)
+
+        const char* category = nullptr;
+        const char* descriptionPrefix = nullptr;
+
+        if (CHECK_PREFIX(kFilePrefix)) {
+          category = "files"; // No trailing slash, the file path will have one
+          descriptionPrefix = "An open";
+        } else if (CHECK_PREFIX(kSocketPrefix)) {
+          category = "sockets/";
+          descriptionPrefix = "A socket";
+        } else if (CHECK_PREFIX(kPipePrefix)) {
+          category = "pipes/";
+          descriptionPrefix = "A pipe";
+        } else if (CHECK_PREFIX(kAnonInodePrefix)) {
+          category = "anon_inodes/";
+          descriptionPrefix = "An anon_inode";
+        } else {
+          category = "";
+          descriptionPrefix = "An uncategorized";
+        }
+
+#undef CHECK_PREFIX
+
+        const nsCString processName(aProcessName);
+        nsPrintfCString entryPath("open-fds/%s/%s%s/%s",
+                                  processName.get(), category, linkPath, fd);
+        nsPrintfCString entryDescription("%s file descriptor opened by the process",
+                                         descriptionPrefix);
+        REPORT(entryPath, UNITS_COUNT, 1, entryDescription);
+      }
+    }
+
+    closedir(d);
+  }
+
+  void
+  CollectKgslReports(nsIHandleReportCallback* aHandleReport,
+                     nsISupports* aData)
+  {
+    // Each process that uses kgsl memory will have an entry under
+    // /sys/kernel/debug/kgsl/proc/<pid>/mem. This file format includes a
+    // header and then entries with types as follows:
+    //   gpuaddr useraddr size id  flags type usage sglen
+    //   hexaddr hexaddr  int  int str   str  str   int
+    // We care primarily about the usage and size.
+
+    // For simplicity numbers will be uint64_t, strings 63 chars max.
+    const char* const kScanFormat =
+      "%" SCNx64 " %" SCNx64 " %" SCNu64 " %" SCNu64
+      " %63s %63s %63s %" SCNu64;
+    const int kNumFields = 8;
+    const size_t kStringSize = 64;
+
+    DIR* d = opendir("/sys/kernel/debug/kgsl/proc/");
+    if (!d) {
+      return;
+    }
+
+    AutoDir dirGuard(d);
+
+    struct dirent* ent;
+    while ((ent = readdir(d))) {
+      const char* pid = ent->d_name;
+
+      // Skip "." and ".." (and any other dotfiles).
+      if (pid[0] == '.') {
+        continue;
+      }
+
+      nsPrintfCString memPath("/sys/kernel/debug/kgsl/proc/%s/mem", pid);
+      FILE* memFile = fopen(memPath.get(), "r");
+      if (NS_WARN_IF(!memFile)) {
+        continue;
+      }
+
+      AutoFile fileGuard(memFile);
+
+      // Attempt to map the pid to a more useful name.
+      nsAutoCString procName;
+      LinuxUtils::GetThreadName(atoi(pid), procName);
+
+      if (procName.IsEmpty()) {
+        procName.Append("pid=");
+        procName.Append(pid);
+      } else {
+        procName.Append(" (pid=");
+        procName.Append(pid);
+        procName.Append(")");
+      }
+
+      uint64_t gpuaddr, useraddr, size, id, sglen;
+      char flags[kStringSize];
+      char type[kStringSize];
+      char usage[kStringSize];
+
+      // Bypass the header line.
+      char buff[1024];
+      Unused << fgets(buff, 1024, memFile);
+
+      while (fscanf(memFile, kScanFormat, &gpuaddr, &useraddr, &size, &id,
+                    flags, type, usage, &sglen) == kNumFields) {
+        nsPrintfCString entryPath("kgsl-memory/%s/%s", procName.get(), usage);
+        REPORT(entryPath, UNITS_BYTES, size,
+               NS_LITERAL_CSTRING("A kgsl graphics memory allocation."));
+      }
+    }
+  }
+};
+
+NS_IMPL_ISUPPORTS(SystemReporter, nsIMemoryReporter)
+
+void
+Init()
+{
+  RegisterStrongMemoryReporter(new SystemReporter());
+}
+
+} // namespace SystemMemoryReporter
+} // namespace mozilla
diff --git a/xpcom/base/SystemMemoryReporter.h b/xpcom/base/SystemMemoryReporter.h
new file mode 100644
index 000000000..e52487613
--- /dev/null
+++ b/xpcom/base/SystemMemoryReporter.h
@@ -0,0 +1,29 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_SystemMemoryReporter_h_
+#define mozilla_SystemMemoryReporter_h_
+
+namespace mozilla {
+namespace SystemMemoryReporter {
+
+// This only works on Linux, but to make callers' lives easier, we stub out
+// empty functions on other platforms.
+
+#if defined(XP_LINUX)
+void
+Init();
+#else
+void
+Init()
+{
+}
+#endif
+
+} // namespace SystemMemoryReporter
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/base/moz.build b/xpcom/base/moz.build
new file mode 100644
index 000000000..d6a336b40
--- /dev/null
+++ b/xpcom/base/moz.build
@@ -0,0 +1,159 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+XPIDL_SOURCES += [
+    'nsIConsoleListener.idl',
+    'nsIConsoleMessage.idl',
+    'nsIConsoleService.idl',
+    'nsICycleCollectorListener.idl',
+    'nsIDebug2.idl',
+    'nsIErrorService.idl',
+    'nsIException.idl',
+    'nsIGZFileWriter.idl',
+    'nsIInterfaceRequestor.idl',
+    'nsIMemory.idl',
+    'nsIMemoryInfoDumper.idl',
+    'nsIMemoryReporter.idl',
+    'nsIMessageLoop.idl',
+    'nsIMutable.idl',
+    'nsIProgrammingLanguage.idl',
+    'nsISecurityConsoleMessage.idl',
+    'nsIStatusReporter.idl',
+    'nsISupports.idl',
+    'nsIUUIDGenerator.idl',
+    'nsIVersionComparator.idl',
+    'nsIWeakReference.idl',
+    'nsrootidl.idl',
+]
+
+if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa':
+    XPIDL_SOURCES += [
+        'nsIMacUtils.idl',
+    ]
+    EXPORTS.mozilla += [
+        'MacHelpers.h',
+    ]
+    UNIFIED_SOURCES += [
+        'MacHelpers.mm',
+    ]
+
+XPIDL_MODULE = 'xpcom_base'
+
+EXPORTS += [
+    'CodeAddressService.h',
+    'ErrorList.h',
+    'nsAgg.h',
+    'nsAlgorithm.h',
+    'nsAutoPtr.h',
+    'nsAutoRef.h',
+    'nsCom.h',
+    'nscore.h',
+    'nsCycleCollector.h',
+    'nsDebugImpl.h',
+    'nsDumpUtils.h',
+    'nsError.h',
+    'nsGZFileWriter.h',
+    'nsIID.h',
+    'nsInterfaceRequestorAgg.h',
+    'nsISizeOf.h',
+    'nsISupportsBase.h',
+    'nsObjCExceptions.h',
+    'nsQueryObject.h',
+    'nsTraceRefcnt.h',
+    'nsWeakPtr.h',
+]
+
+if CONFIG['OS_ARCH'] == 'WINNT':
+    EXPORTS += [
+        'nsWindowsHelpers.h',
+    ]
+
+EXPORTS.mozilla += [
+    'AvailableMemoryTracker.h',
+    'ClearOnShutdown.h',
+    'CountingAllocatorBase.h',
+    'CycleCollectedJSContext.h',
+    'Debug.h',
+    'DebuggerOnGCRunnable.h',
+    'DeferredFinalize.h',
+    'ErrorNames.h',
+    'HoldDropJSObjects.h',
+    'JSObjectHolder.h',
+    'LinuxUtils.h',
+    'Logging.h',
+    'nsMemoryInfoDumper.h',
+    'OwningNonNull.h',
+    'StaticMutex.h',
+    'StaticPtr.h',
+    'SystemMemoryReporter.h',
+]
+
+# nsDebugImpl isn't unified because we disable PGO so that NS_ABORT_OOM isn't
+# optimized away oddly.
+SOURCES += [
+    'nsDebugImpl.cpp',
+]
+SOURCES['nsDebugImpl.cpp'].no_pgo = True
+
+UNIFIED_SOURCES += [
+    'AvailableMemoryTracker.cpp',
+    'ClearOnShutdown.cpp',
+    'CycleCollectedJSContext.cpp',
+    'Debug.cpp',
+    'DebuggerOnGCRunnable.cpp',
+    'DeferredFinalize.cpp',
+    'ErrorNames.cpp',
+    'HoldDropJSObjects.cpp',
+    'JSObjectHolder.cpp',
+    'Logging.cpp',
+    'LogModulePrefWatcher.cpp',
+    'nsConsoleMessage.cpp',
+    'nsConsoleService.cpp',
+    'nsCycleCollector.cpp',
+    'nsCycleCollectorTraceJSHelpers.cpp',
+    'nsDumpUtils.cpp',
+    'nsErrorService.cpp',
+    'nsGZFileWriter.cpp',
+    'nsInterfaceRequestorAgg.cpp',
+    'nsMemoryImpl.cpp',
+    'nsMemoryInfoDumper.cpp',
+    'nsMemoryReporterManager.cpp',
+    'nsMessageLoop.cpp',
+    'NSPRLogModulesParser.cpp',
+    'nsSecurityConsoleMessage.cpp',
+    'nsStatusReporterManager.cpp',
+    'nsSystemInfo.cpp',
+    'nsTraceRefcnt.cpp',
+    'nsUUIDGenerator.cpp',
+    'nsVersionComparatorImpl.cpp',
+]
+
+if CONFIG['OS_ARCH'] == 'Linux':
+    SOURCES += [
+        'LinuxUtils.cpp',
+        'SystemMemoryReporter.cpp',
+    ]
+
+if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa':
+    SOURCES += [
+        'nsMacUtilsImpl.cpp',
+    ]
+elif CONFIG['MOZ_WIDGET_TOOLKIT'] == 'windows':
+    SOURCES += [
+        'nsCrashOnException.cpp',
+    ]
+
+include('/ipc/chromium/chromium-config.mozbuild')
+
+FINAL_LIBRARY = 'xul'
+
+LOCAL_INCLUDES += [
+    '../build',
+    '/xpcom/ds',
+]
+
+if 'gtk' in CONFIG['MOZ_WIDGET_TOOLKIT']:
+    CXXFLAGS += CONFIG['TK_CFLAGS']
diff --git a/xpcom/base/nsAgg.h b/xpcom/base/nsAgg.h
new file mode 100644
index 000000000..8dcf8067e
--- /dev/null
+++ b/xpcom/base/nsAgg.h
@@ -0,0 +1,336 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsAgg_h___
+#define nsAgg_h___
+
+#include "nsISupports.h"
+#include "nsCycleCollectionParticipant.h"
+
+
+////////////////////////////////////////////////////////////////////////////////
+
+// Put NS_DECL_AGGREGATED or NS_DECL_CYCLE_COLLECTING_AGGREGATED in your class's
+// declaration.
+#define NS_DECL_AGGREGATED                                                  \
+  NS_DECL_ISUPPORTS                                                         \
+  NS_DECL_AGGREGATED_HELPER
+
+#define NS_DECL_CYCLE_COLLECTING_AGGREGATED                                 \
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS                                        \
+  NS_DECL_AGGREGATED_HELPER
+
+#define NS_DECL_AGGREGATED_HELPER                                           \
+public:                                                                     \
+                                                                            \
+    /**                                                                     \
+     * Returns the nsISupports pointer of the inner object (aka the         \
+     * aggregatee). This pointer is really only useful to the outer object  \
+     * (aka the aggregator), which can use it to hold on to the inner       \
+     * object. Anything else wants the nsISupports pointer of the outer     \
+     * object (gotten by QI'ing inner or outer to nsISupports). This method \
+     * returns a non-addrefed pointer.                                      \
+     * @return the nsISupports pointer of the inner object                  \
+     */                                                                     \
+    nsISupports* InnerObject(void) { return &fAggregated; }                 \
+                                                                            \
+    /**                                                                     \
+     * Returns true if this object is part of an aggregated object.      \
+     */                                                                     \
+    bool IsPartOfAggregated(void) { return fOuter != InnerObject(); }     \
+                                                                            \
+private:                                                                    \
+                                                                            \
+    /* You must implement this operation instead of the nsISupports */      \
+    /* methods. */                                                          \
+    nsresult                                                                \
+    AggregatedQueryInterface(const nsIID& aIID, void** aInstancePtr);       \
+                                                                            \
+    class Internal : public nsISupports {                                   \
+    public:                                                                 \
+                                                                            \
+        Internal() {}                                                       \
+                                                                            \
+        NS_IMETHOD QueryInterface(const nsIID& aIID, void** aInstancePtr);  \
+        NS_IMETHOD_(MozExternalRefCountType) AddRef(void);                  \
+        NS_IMETHOD_(MozExternalRefCountType) Release(void);                 \
+                                                                            \
+        NS_DECL_OWNINGTHREAD                                                \
+    };                                                                      \
+                                                                            \
+    friend class Internal;                                                  \
+                                                                            \
+    nsISupports* MOZ_UNSAFE_REF("fOuter can either point to fAggregated "   \
+                                "or to an outer object, and the safety "    \
+                                "of this reference depends on the exact "   \
+                                "lifetime semantics of the AddRef/Release " \
+                                "functions created by these macros.")       \
+                        fOuter;                                             \
+    Internal            fAggregated;                                        \
+                                                                            \
+public:                                                                     \
+
+#define NS_DECL_AGGREGATED_CYCLE_COLLECTION_CLASS(_class)                   \
+class NS_CYCLE_COLLECTION_INNERCLASS                                        \
+ : public nsXPCOMCycleCollectionParticipant                                 \
+{                                                                           \
+public:                                                                     \
+  NS_IMETHOD_(void) Unlink(void *p) override;                               \
+  NS_IMETHOD Traverse(void *p, nsCycleCollectionTraversalCallback &cb)      \
+    override;                                                               \
+  NS_DECL_CYCLE_COLLECTION_CLASS_NAME_METHOD(_class)                        \
+  NS_IMETHOD_(void) DeleteCycleCollectable(void* p) override                \
+  {                                                                         \
+    NS_CYCLE_COLLECTION_CLASSNAME(_class)::                                 \
+      Downcast(static_cast<nsISupports*>(p))->DeleteCycleCollectable();     \
+  }                                                                         \
+  static _class* Downcast(nsISupports* s)                                   \
+  {                                                                         \
+    return (_class*)((char*)(s) - offsetof(_class, fAggregated));           \
+  }                                                                         \
+  static nsISupports* Upcast(_class *p)                                     \
+  {                                                                         \
+    return p->InnerObject();                                                \
+  }                                                                         \
+  static nsXPCOMCycleCollectionParticipant* GetParticipant()                \
+  {                                                                         \
+    return &_class::NS_CYCLE_COLLECTION_INNERNAME;                          \
+  }                                                                         \
+};                                                                          \
+NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class);                                \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
+
+// Put this in your class's constructor:
+#define NS_INIT_AGGREGATED(outer)                                           \
+  PR_BEGIN_MACRO                                                            \
+    fOuter = outer ? outer : &fAggregated;                                  \
+  PR_END_MACRO
+
+
+// Put this in your class's implementation file:
+#define NS_IMPL_AGGREGATED(_class)                                          \
+                                                                            \
+NS_IMPL_AGGREGATED_HELPER(_class)                                           \
+                                                                            \
+NS_IMETHODIMP_(MozExternalRefCountType)                                     \
+_class::Internal::AddRef(void)                                              \
+{                                                                           \
+    _class* agg = (_class*)((char*)(this) - offsetof(_class, fAggregated)); \
+    MOZ_ASSERT(int32_t(agg->mRefCnt) >= 0, "illegal refcnt");               \
+    NS_ASSERT_OWNINGTHREAD(_class);                                         \
+    ++agg->mRefCnt;                                                         \
+    NS_LOG_ADDREF(this, agg->mRefCnt, #_class, sizeof(*this));              \
+    return agg->mRefCnt;                                                    \
+}                                                                           \
+                                                                            \
+NS_IMETHODIMP_(MozExternalRefCountType)                                     \
+_class::Internal::Release(void)                                             \
+{                                                                           \
+    _class* agg = (_class*)((char*)(this) - offsetof(_class, fAggregated)); \
+    MOZ_ASSERT(int32_t(agg->mRefCnt) > 0, "dup release");                   \
+    NS_ASSERT_OWNINGTHREAD(_class);                                         \
+    --agg->mRefCnt;                                                         \
+    NS_LOG_RELEASE(this, agg->mRefCnt, #_class);                            \
+    if (agg->mRefCnt == 0) {                                                \
+        agg->mRefCnt = 1; /* stabilize */                                   \
+        delete agg;                                                         \
+        return 0;                                                           \
+    }                                                                       \
+    return agg->mRefCnt;                                                    \
+}                                                                           \
+
+#define NS_IMPL_CYCLE_COLLECTING_AGGREGATED(_class)                         \
+                                                                            \
+NS_IMPL_AGGREGATED_HELPER(_class)                                           \
+                                                                            \
+NS_IMETHODIMP_(MozExternalRefCountType)                                     \
+_class::Internal::AddRef(void)                                              \
+{                                                                           \
+    _class* agg = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Downcast(this);    \
+    MOZ_ASSERT(int32_t(agg->mRefCnt) >= 0, "illegal refcnt");               \
+    NS_ASSERT_OWNINGTHREAD_AGGREGATE(agg, _class);                          \
+    nsrefcnt count = agg->mRefCnt.incr(this);                               \
+    NS_LOG_ADDREF(this, count, #_class, sizeof(*agg));                      \
+    return count;                                                           \
+}                                                                           \
+NS_IMETHODIMP_(MozExternalRefCountType)                                     \
+_class::Internal::Release(void)                                             \
+{                                                                           \
+    _class* agg = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Downcast(this);    \
+    MOZ_ASSERT(int32_t(agg->mRefCnt) > 0, "dup release");                   \
+    NS_ASSERT_OWNINGTHREAD_AGGREGATE(agg, _class);                          \
+    nsrefcnt count = agg->mRefCnt.decr(this);                               \
+    NS_LOG_RELEASE(this, count, #_class);                                   \
+    return count;                                                           \
+}                                                                           \
+NS_IMETHODIMP_(void)                                                        \
+_class::DeleteCycleCollectable(void)                                        \
+{                                                                           \
+  delete this;                                                              \
+}
+
+#define NS_IMPL_AGGREGATED_HELPER(_class)                                   \
+NS_IMETHODIMP                                                               \
+_class::QueryInterface(const nsIID& aIID, void** aInstancePtr)              \
+{                                                                           \
+    return fOuter->QueryInterface(aIID, aInstancePtr);                      \
+}                                                                           \
+                                                                            \
+NS_IMETHODIMP_(MozExternalRefCountType)                                     \
+_class::AddRef(void)                                                        \
+{                                                                           \
+    return fOuter->AddRef();                                                \
+}                                                                           \
+                                                                            \
+NS_IMETHODIMP_(MozExternalRefCountType)                                     \
+_class::Release(void)                                                       \
+{                                                                           \
+    return fOuter->Release();                                               \
+}                                                                           \
+                                                                            \
+NS_IMETHODIMP                                                               \
+_class::Internal::QueryInterface(const nsIID& aIID, void** aInstancePtr)    \
+{                                                                           \
+    _class* agg = (_class*)((char*)(this) - offsetof(_class, fAggregated)); \
+    return agg->AggregatedQueryInterface(aIID, aInstancePtr);               \
+}                                                                           \
+
+/**
+ * To make aggregated objects participate in cycle collection we need to enable
+ * the outer object (aggregator) to traverse/unlink the objects held by the
+ * inner object (the aggregatee). We can't just make the inner object QI'able to
+ * NS_CYCLECOLLECTIONPARTICIPANT_IID, we don't want to return the inner object's
+ * nsCycleCollectionParticipant for the outer object (which will happen if the
+ * outer object doesn't participate in cycle collection itself).
+ * NS_AGGREGATED_CYCLECOLLECTIONPARTICIPANT_IID enables the outer object to get
+ * the inner objects nsCycleCollectionParticipant.
+ *
+ * There are three cases:
+ *   - No aggregation
+ *     QI'ing to NS_CYCLECOLLECTIONPARTICIPANT_IID will return the inner
+ *     object's nsCycleCollectionParticipant.
+ *
+ *   - Aggregation and outer object does not participate in cycle collection
+ *     QI'ing to NS_CYCLECOLLECTIONPARTICIPANT_IID will not return anything.
+ *
+ *   - Aggregation and outer object does participate in cycle collection
+ *     QI'ing to NS_CYCLECOLLECTIONPARTICIPANT_IID will return the outer
+ *     object's nsCycleCollectionParticipant. The outer object's
+ *     nsCycleCollectionParticipant can then QI the inner object to
+ *     NS_AGGREGATED_CYCLECOLLECTIONPARTICIPANT_IID to get the inner object's
+ *     nsCycleCollectionParticipant, which it can use to traverse/unlink the
+ *     objects reachable from the inner object.
+ */
+#define NS_AGGREGATED_CYCLECOLLECTIONPARTICIPANT_IID                        \
+{                                                                           \
+    0x32889b7e,                                                             \
+    0xe4fe,                                                                 \
+    0x43f4,                                                                 \
+    { 0x85, 0x31, 0xb5, 0x28, 0x23, 0xa2, 0xe9, 0xfc }                      \
+}
+
+/**
+ * Just holds the IID so NS_GET_IID works.
+ */
+class nsAggregatedCycleCollectionParticipant
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_AGGREGATED_CYCLECOLLECTIONPARTICIPANT_IID)
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsAggregatedCycleCollectionParticipant,
+                              NS_AGGREGATED_CYCLECOLLECTIONPARTICIPANT_IID)
+
+// for use with QI macros in nsISupportsUtils.h:
+
+#define NS_INTERFACE_MAP_BEGIN_AGGREGATED(_class)                           \
+  NS_IMPL_AGGREGATED_QUERY_HEAD(_class)
+
+#define NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION_AGGREGATED(_class)          \
+  NS_IMPL_QUERY_CYCLE_COLLECTION(_class)
+
+#define NS_INTERFACE_MAP_ENTRIES_CYCLE_COLLECTION_AGGREGATED(_class)        \
+  NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION_AGGREGATED(_class)                \
+  NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION_ISUPPORTS(_class)
+
+#define NS_IMPL_AGGREGATED_QUERY_HEAD(_class)                               \
+nsresult                                                                    \
+_class::AggregatedQueryInterface(REFNSIID aIID, void** aInstancePtr)        \
+{                                                                           \
+  NS_ASSERTION(aInstancePtr,                                                \
+               "AggregatedQueryInterface requires a non-NULL result ptr!"); \
+  if ( !aInstancePtr )                                                      \
+    return NS_ERROR_NULL_POINTER;                                           \
+  nsISupports* foundInterface;                                              \
+  if ( aIID.Equals(NS_GET_IID(nsISupports)) )                               \
+    foundInterface = InnerObject();                                         \
+  else
+
+#define NS_IMPL_AGGREGATED_QUERY_CYCLE_COLLECTION(_class)                   \
+  if (aIID.Equals(IsPartOfAggregated() ?                                    \
+                  NS_GET_IID(nsCycleCollectionParticipant) :                \
+                  NS_GET_IID(nsAggregatedCycleCollectionParticipant)))      \
+    foundInterface = NS_CYCLE_COLLECTION_PARTICIPANT(_class);               \
+  else
+
+#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_AGGREGATED(_class)          \
+  NS_IMETHODIMP                                                             \
+  NS_CYCLE_COLLECTION_CLASSNAME(_class)::Traverse                           \
+                         (void *p, nsCycleCollectionTraversalCallback &cb)  \
+  {                                                                         \
+    nsISupports *s = static_cast<nsISupports*>(p);                          \
+    MOZ_ASSERT(CheckForRightISupports(s),                                   \
+               "not the nsISupports pointer we expect");                    \
+    _class *tmp = static_cast<_class*>(Downcast(s));                        \
+    if (!tmp->IsPartOfAggregated())                                         \
+        NS_IMPL_CYCLE_COLLECTION_DESCRIBE(_class, tmp->mRefCnt.get())
+
+#define NS_GENERIC_AGGREGATED_CONSTRUCTOR(_InstanceClass)                   \
+static nsresult                                                             \
+_InstanceClass##Constructor(nsISupports *aOuter, REFNSIID aIID,             \
+                            void **aResult)                                 \
+{                                                                           \
+    *aResult = nullptr;                                                     \
+    if (NS_WARN_IF(aOuter && !aIID.Equals(NS_GET_IID(nsISupports))))        \
+        return NS_ERROR_INVALID_ARG;                                        \
+                                                                            \
+    RefPtr<_InstanceClass> inst = new _InstanceClass(aOuter);               \
+    if (!inst) {                                                            \
+        return NS_ERROR_OUT_OF_MEMORY;                                      \
+    }                                                                       \
+                                                                            \
+    nsISupports* inner = inst->InnerObject();                               \
+    nsresult rv = inner->QueryInterface(aIID, aResult);                     \
+                                                                            \
+    return rv;                                                              \
+}                                                                           \
+
+#define NS_GENERIC_AGGREGATED_CONSTRUCTOR_INIT(_InstanceClass, _InitMethod) \
+static nsresult                                                             \
+_InstanceClass##Constructor(nsISupports *aOuter, REFNSIID aIID,             \
+                            void **aResult)                                 \
+{                                                                           \
+    *aResult = nullptr;                                                     \
+    if (NS_WARN_IF(aOuter && !aIID.Equals(NS_GET_IID(nsISupports))))        \
+        return NS_ERROR_INVALID_ARG;                                        \
+                                                                            \
+    RefPtr<_InstanceClass> inst = new _InstanceClass(aOuter);               \
+    if (!inst) {                                                            \
+        return NS_ERROR_OUT_OF_MEMORY;                                      \
+    }                                                                       \
+                                                                            \
+    nsISupports* inner = inst->InnerObject();                               \
+    NS_ADDREF(inner);                                                       \
+    nsresult rv = inst->_InitMethod();                                      \
+    if (NS_SUCCEEDED(rv)) {                                                 \
+        rv = inner->QueryInterface(aIID, aResult);                          \
+    }                                                                       \
+    NS_RELEASE(inner);                                                      \
+                                                                            \
+    return rv;                                                              \
+}                                                                           \
+
+#endif /* nsAgg_h___ */
diff --git a/xpcom/base/nsAlgorithm.h b/xpcom/base/nsAlgorithm.h
new file mode 100644
index 000000000..ceaa3ace3
--- /dev/null
+++ b/xpcom/base/nsAlgorithm.h
@@ -0,0 +1,75 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsAlgorithm_h___
+#define nsAlgorithm_h___
+
+#include "nsCharTraits.h"  // for |nsCharSourceTraits|, |nsCharSinkTraits|
+
+template <class T>
+inline T
+NS_ROUNDUP(const T& aA, const T& aB)
+{
+  return ((aA + (aB - 1)) / aB) * aB;
+}
+
+// We use these instead of std::min/max because we can't include the algorithm
+// header in all of XPCOM because the stl wrappers will error out when included
+// in parts of XPCOM. These functions should never be used outside of XPCOM.
+template <class T>
+inline const T&
+XPCOM_MIN(const T& aA, const T& aB)
+{
+  return aB < aA ? aB : aA;
+}
+
+// Must return b when a == b in case a is -0
+template <class T>
+inline const T&
+XPCOM_MAX(const T& aA, const T& aB)
+{
+  return aA > aB ? aA : aB;
+}
+
+namespace mozilla {
+
+template <class T>
+inline const T&
+clamped(const T& aA, const T& aMin, const T& aMax)
+{
+  MOZ_ASSERT(aMax >= aMin,
+             "clamped(): aMax must be greater than or equal to aMin");
+  return XPCOM_MIN(XPCOM_MAX(aA, aMin), aMax);
+}
+
+} // namespace mozilla
+
+template <class InputIterator, class T>
+inline uint32_t
+NS_COUNT(InputIterator& aFirst, const InputIterator& aLast, const T& aValue)
+{
+  uint32_t result = 0;
+  for (; aFirst != aLast; ++aFirst)
+    if (*aFirst == aValue) {
+      ++result;
+    }
+  return result;
+}
+
+template <class InputIterator, class OutputIterator>
+inline OutputIterator&
+copy_string(const InputIterator& aFirst, const InputIterator& aLast,
+            OutputIterator& aResult)
+{
+  typedef nsCharSourceTraits<InputIterator> source_traits;
+  typedef nsCharSinkTraits<OutputIterator>  sink_traits;
+
+  sink_traits::write(aResult, source_traits::read(aFirst),
+                     source_traits::readable_distance(aFirst, aLast));
+  return aResult;
+}
+
+#endif // !defined(nsAlgorithm_h___)
diff --git a/xpcom/base/nsAllocator.h b/xpcom/base/nsAllocator.h
new file mode 100644
index 000000000..a9ad1c70a
--- /dev/null
+++ b/xpcom/base/nsAllocator.h
@@ -0,0 +1,17 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+////////////////////////////////////////////////////////////////////////////////
+// obsolete
+////////////////////////////////////////////////////////////////////////////////
+
+#ifndef nsAllocator_h__
+#define nsAllocator_h__
+
+#include "nsAgg.h"
+#include "nsIFactory.h"
+
+#endif // nsAllocator_h__
diff --git a/xpcom/base/nsAutoPtr.h b/xpcom/base/nsAutoPtr.h
new file mode 100644
index 000000000..b5a15000c
--- /dev/null
+++ b/xpcom/base/nsAutoPtr.h
@@ -0,0 +1,454 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsAutoPtr_h
+#define nsAutoPtr_h
+
+#include "nsCOMPtr.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/TypeTraits.h"
+
+#include "nsCycleCollectionNoteChild.h"
+#include "mozilla/MemoryReporting.h"
+
+/*****************************************************************************/
+
+// template <class T> class nsAutoPtrGetterTransfers;
+
+template <class T>
+class nsAutoPtr
+{
+private:
+  static_assert(!mozilla::IsScalar<T>::value, "If you are using "
+                "nsAutoPtr to hold an array, use UniquePtr<T[]> instead");
+
+  void**
+  begin_assignment()
+  {
+    assign(0);
+    return reinterpret_cast<void**>(&mRawPtr);
+  }
+
+  void
+  assign(T* aNewPtr)
+  {
+    T* oldPtr = mRawPtr;
+
+    if (aNewPtr && aNewPtr == oldPtr) {
+      NS_RUNTIMEABORT("Logic flaw in the caller");
+    }
+
+    mRawPtr = aNewPtr;
+    delete oldPtr;
+  }
+
+  // |class Ptr| helps us prevent implicit "copy construction"
+  // through |operator T*() const| from a |const nsAutoPtr<T>|
+  // because two implicit conversions in a row aren't allowed.
+  // It still allows assignment from T* through implicit conversion
+  // from |T*| to |nsAutoPtr<T>::Ptr|
+  class Ptr
+  {
+  public:
+    MOZ_IMPLICIT Ptr(T* aPtr)
+      : mPtr(aPtr)
+    {
+    }
+
+    operator T*() const
+    {
+      return mPtr;
+    }
+
+  private:
+    T* MOZ_NON_OWNING_REF mPtr;
+  };
+
+private:
+  T* MOZ_OWNING_REF mRawPtr;
+
+public:
+  typedef T element_type;
+
+  ~nsAutoPtr()
+  {
+    delete mRawPtr;
+  }
+
+  // Constructors
+
+  nsAutoPtr()
+    : mRawPtr(0)
+    // default constructor
+  {
+  }
+
+  MOZ_IMPLICIT nsAutoPtr(Ptr aRawPtr)
+    : mRawPtr(aRawPtr)
+    // construct from a raw pointer (of the right type)
+  {
+  }
+
+  // This constructor shouldn't exist; we should just use the &&
+  // constructor.
+  nsAutoPtr(nsAutoPtr<T>& aSmartPtr)
+    : mRawPtr(aSmartPtr.forget())
+    // Construct by transferring ownership from another smart pointer.
+  {
+  }
+
+  template <typename I>
+  MOZ_IMPLICIT nsAutoPtr(nsAutoPtr<I>& aSmartPtr)
+    : mRawPtr(aSmartPtr.forget())
+    // Construct by transferring ownership from another smart pointer.
+  {
+  }
+
+  nsAutoPtr(nsAutoPtr<T>&& aSmartPtr)
+    : mRawPtr(aSmartPtr.forget())
+    // Construct by transferring ownership from another smart pointer.
+  {
+  }
+
+  template <typename I>
+  MOZ_IMPLICIT nsAutoPtr(nsAutoPtr<I>&& aSmartPtr)
+    : mRawPtr(aSmartPtr.forget())
+    // Construct by transferring ownership from another smart pointer.
+  {
+  }
+
+  // Assignment operators
+
+  nsAutoPtr<T>&
+  operator=(T* aRhs)
+  // assign from a raw pointer (of the right type)
+  {
+    assign(aRhs);
+    return *this;
+  }
+
+  nsAutoPtr<T>& operator=(nsAutoPtr<T>& aRhs)
+  // assign by transferring ownership from another smart pointer.
+  {
+    assign(aRhs.forget());
+    return *this;
+  }
+
+  template <typename I>
+  nsAutoPtr<T>& operator=(nsAutoPtr<I>& aRhs)
+  // assign by transferring ownership from another smart pointer.
+  {
+    assign(aRhs.forget());
+    return *this;
+  }
+
+  nsAutoPtr<T>& operator=(nsAutoPtr<T>&& aRhs)
+  {
+    assign(aRhs.forget());
+    return *this;
+  }
+
+  template <typename I>
+  nsAutoPtr<T>& operator=(nsAutoPtr<I>&& aRhs)
+  {
+    assign(aRhs.forget());
+    return *this;
+  }
+
+  // Other pointer operators
+
+  T*
+  get() const
+  /*
+    Prefer the implicit conversion provided automatically by
+    |operator T*() const|.  Use |get()| _only_ to resolve
+    ambiguity.
+  */
+  {
+    return mRawPtr;
+  }
+
+  operator T*() const
+  /*
+    ...makes an |nsAutoPtr| act like its underlying raw pointer
+    type  whenever it is used in a context where a raw pointer
+    is expected.  It is this operator that makes an |nsAutoPtr|
+    substitutable for a raw pointer.
+
+    Prefer the implicit use of this operator to calling |get()|,
+    except where necessary to resolve ambiguity.
+  */
+  {
+    return get();
+  }
+
+  T*
+  forget()
+  {
+    T* temp = mRawPtr;
+    mRawPtr = 0;
+    return temp;
+  }
+
+  T*
+  operator->() const
+  {
+    NS_PRECONDITION(mRawPtr != 0,
+                    "You can't dereference a NULL nsAutoPtr with operator->().");
+    return get();
+  }
+
+  template <typename R, typename... Args>
+  class Proxy
+  {
+    typedef R (T::*member_function)(Args...);
+    T* mRawPtr;
+    member_function mFunction;
+  public:
+    Proxy(T* aRawPtr, member_function aFunction)
+      : mRawPtr(aRawPtr),
+        mFunction(aFunction)
+    {
+    }
+    template<typename... ActualArgs>
+    R operator()(ActualArgs&&... aArgs)
+    {
+      return ((*mRawPtr).*mFunction)(mozilla::Forward<ActualArgs>(aArgs)...);
+    }
+  };
+
+  template <typename R, typename C, typename... Args>
+  Proxy<R, Args...> operator->*(R (C::*aFptr)(Args...)) const
+  {
+    NS_PRECONDITION(mRawPtr != 0,
+                    "You can't dereference a NULL nsAutoPtr with operator->*().");
+    return Proxy<R, Args...>(get(), aFptr);
+  }
+
+  nsAutoPtr<T>*
+  get_address()
+  // This is not intended to be used by clients.  See |address_of|
+  // below.
+  {
+    return this;
+  }
+
+  const nsAutoPtr<T>*
+  get_address() const
+  // This is not intended to be used by clients.  See |address_of|
+  // below.
+  {
+    return this;
+  }
+
+public:
+  T&
+  operator*() const
+  {
+    NS_PRECONDITION(mRawPtr != 0,
+                    "You can't dereference a NULL nsAutoPtr with operator*().");
+    return *get();
+  }
+
+  T**
+  StartAssignment()
+  {
+#ifndef NSCAP_FEATURE_INLINE_STARTASSIGNMENT
+    return reinterpret_cast<T**>(begin_assignment());
+#else
+    assign(0);
+    return reinterpret_cast<T**>(&mRawPtr);
+#endif
+  }
+};
+
+template <class T>
+inline nsAutoPtr<T>*
+address_of(nsAutoPtr<T>& aPtr)
+{
+  return aPtr.get_address();
+}
+
+template <class T>
+inline const nsAutoPtr<T>*
+address_of(const nsAutoPtr<T>& aPtr)
+{
+  return aPtr.get_address();
+}
+
+template <class T>
+class nsAutoPtrGetterTransfers
+/*
+  ...
+
+  This class is designed to be used for anonymous temporary objects in the
+  argument list of calls that return COM interface pointers, e.g.,
+
+    nsAutoPtr<IFoo> fooP;
+    ...->GetTransferedPointer(getter_Transfers(fooP))
+
+  DO NOT USE THIS TYPE DIRECTLY IN YOUR CODE.  Use |getter_Transfers()| instead.
+
+  When initialized with a |nsAutoPtr|, as in the example above, it returns
+  a |void**|, a |T**|, or an |nsISupports**| as needed, that the
+  outer call (|GetTransferedPointer| in this case) can fill in.
+
+  This type should be a nested class inside |nsAutoPtr<T>|.
+*/
+{
+public:
+  explicit
+  nsAutoPtrGetterTransfers(nsAutoPtr<T>& aSmartPtr)
+    : mTargetSmartPtr(aSmartPtr)
+  {
+    // nothing else to do
+  }
+
+  operator void**()
+  {
+    return reinterpret_cast<void**>(mTargetSmartPtr.StartAssignment());
+  }
+
+  operator T**()
+  {
+    return mTargetSmartPtr.StartAssignment();
+  }
+
+  T*&
+  operator*()
+  {
+    return *(mTargetSmartPtr.StartAssignment());
+  }
+
+private:
+  nsAutoPtr<T>& mTargetSmartPtr;
+};
+
+template <class T>
+inline nsAutoPtrGetterTransfers<T>
+getter_Transfers(nsAutoPtr<T>& aSmartPtr)
+/*
+  Used around a |nsAutoPtr| when
+  ...makes the class |nsAutoPtrGetterTransfers<T>| invisible.
+*/
+{
+  return nsAutoPtrGetterTransfers<T>(aSmartPtr);
+}
+
+
+
+// Comparing two |nsAutoPtr|s
+
+template <class T, class U>
+inline bool
+operator==(const nsAutoPtr<T>& aLhs, const nsAutoPtr<U>& aRhs)
+{
+  return static_cast<const T*>(aLhs.get()) == static_cast<const U*>(aRhs.get());
+}
+
+
+template <class T, class U>
+inline bool
+operator!=(const nsAutoPtr<T>& aLhs, const nsAutoPtr<U>& aRhs)
+{
+  return static_cast<const T*>(aLhs.get()) != static_cast<const U*>(aRhs.get());
+}
+
+
+// Comparing an |nsAutoPtr| to a raw pointer
+
+template <class T, class U>
+inline bool
+operator==(const nsAutoPtr<T>& aLhs, const U* aRhs)
+{
+  return static_cast<const T*>(aLhs.get()) == static_cast<const U*>(aRhs);
+}
+
+template <class T, class U>
+inline bool
+operator==(const U* aLhs, const nsAutoPtr<T>& aRhs)
+{
+  return static_cast<const U*>(aLhs) == static_cast<const T*>(aRhs.get());
+}
+
+template <class T, class U>
+inline bool
+operator!=(const nsAutoPtr<T>& aLhs, const U* aRhs)
+{
+  return static_cast<const T*>(aLhs.get()) != static_cast<const U*>(aRhs);
+}
+
+template <class T, class U>
+inline bool
+operator!=(const U* aLhs, const nsAutoPtr<T>& aRhs)
+{
+  return static_cast<const U*>(aLhs) != static_cast<const T*>(aRhs.get());
+}
+
+template <class T, class U>
+inline bool
+operator==(const nsAutoPtr<T>& aLhs, U* aRhs)
+{
+  return static_cast<const T*>(aLhs.get()) == const_cast<const U*>(aRhs);
+}
+
+template <class T, class U>
+inline bool
+operator==(U* aLhs, const nsAutoPtr<T>& aRhs)
+{
+  return const_cast<const U*>(aLhs) == static_cast<const T*>(aRhs.get());
+}
+
+template <class T, class U>
+inline bool
+operator!=(const nsAutoPtr<T>& aLhs, U* aRhs)
+{
+  return static_cast<const T*>(aLhs.get()) != const_cast<const U*>(aRhs);
+}
+
+template <class T, class U>
+inline bool
+operator!=(U* aLhs, const nsAutoPtr<T>& aRhs)
+{
+  return const_cast<const U*>(aLhs) != static_cast<const T*>(aRhs.get());
+}
+
+
+
+// Comparing an |nsAutoPtr| to |nullptr|
+
+template <class T>
+inline bool
+operator==(const nsAutoPtr<T>& aLhs, decltype(nullptr))
+{
+  return aLhs.get() == nullptr;
+}
+
+template <class T>
+inline bool
+operator==(decltype(nullptr), const nsAutoPtr<T>& aRhs)
+{
+  return nullptr == aRhs.get();
+}
+
+template <class T>
+inline bool
+operator!=(const nsAutoPtr<T>& aLhs, decltype(nullptr))
+{
+  return aLhs.get() != nullptr;
+}
+
+template <class T>
+inline bool
+operator!=(decltype(nullptr), const nsAutoPtr<T>& aRhs)
+{
+  return nullptr != aRhs.get();
+}
+
+
+/*****************************************************************************/
+
+#endif // !defined(nsAutoPtr_h)
diff --git a/xpcom/base/nsAutoRef.h b/xpcom/base/nsAutoRef.h
new file mode 100644
index 000000000..9986c8a56
--- /dev/null
+++ b/xpcom/base/nsAutoRef.h
@@ -0,0 +1,672 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsAutoRef_h_
+#define nsAutoRef_h_
+
+#include "mozilla/Attributes.h"
+
+#include "nscore.h" // for nullptr, bool
+
+template <class T> class nsSimpleRef;
+template <class T> class nsAutoRefBase;
+template <class T> class nsReturnRef;
+template <class T> class nsReturningRef;
+
+/**
+ * template <class T> class nsAutoRef
+ *
+ * A class that holds a handle to a resource that must be released.
+ * No reference is added on construction.
+ *
+ * No copy constructor nor copy assignment operators are available, so the
+ * resource will be held until released on destruction or explicitly
+ * |reset()| or transferred through provided methods.
+ *
+ * The publicly available methods are the public methods on this class and its
+ * public base classes |nsAutoRefBase<T>| and |nsSimpleRef<T>|.
+ *
+ * For ref-counted resources see also |nsCountedRef<T>|.
+ * For function return values see |nsReturnRef<T>|.
+ *
+ * For each class |T|, |nsAutoRefTraits<T>| or |nsSimpleRef<T>| must be
+ * specialized to use |nsAutoRef<T>| and |nsCountedRef<T>|.
+ *
+ * @param T  A class identifying the type of reference held by the
+ *           |nsAutoRef<T>| and the unique set methods for managing references
+ *           to the resource (defined by |nsAutoRefTraits<T>| or
+ *           |nsSimpleRef<T>|).
+ *
+ *           Often this is the class representing the resource.  Sometimes a
+ *           new possibly-incomplete class may need to be declared.
+ *
+ *
+ * Example:  An Automatically closing file descriptor
+ *
+ * // References that are simple integral types (as file-descriptors are)
+ * // usually need a new class to represent the resource and how to handle its
+ * // references.
+ * class nsRawFD;
+ *
+ * // Specializing nsAutoRefTraits<nsRawFD> describes how to manage file
+ * // descriptors, so that nsAutoRef<nsRawFD> provides automatic closing of
+ * // its file descriptor on destruction.
+ * template <>
+ * class nsAutoRefTraits<nsRawFD> {
+ * public:
+ *     // The file descriptor is held in an int.
+ *     typedef int RawRef;
+ *     // -1 means that there is no file associated with the handle.
+ *     static int Void() { return -1; }
+ *     // The file associated with a file descriptor is released with close().
+ *     static void Release(RawRef aFD) { close(aFD); }
+ * };
+ *
+ * // A function returning a file descriptor that must be closed.
+ * nsReturnRef<nsRawFD> get_file(const char *filename) {
+ *     // Constructing from a raw file descriptor assumes ownership.
+ *     nsAutoRef<nsRawFD> fd(open(filename, O_RDONLY));
+ *     fcntl(fd, F_SETFD, FD_CLOEXEC);
+ *     return fd.out();
+ * }
+ *
+ * void f() {
+ *     unsigned char buf[1024];
+ *
+ *     // Hold a file descriptor for /etc/hosts in fd1.
+ *     nsAutoRef<nsRawFD> fd1(get_file("/etc/hosts"));
+ *
+ *     nsAutoRef<nsRawFD> fd2;
+ *     fd2.steal(fd1); // fd2 takes the file descriptor from fd1
+ *     ssize_t count = read(fd1, buf, 1024); // error fd1 has no file
+ *     count = read(fd2, buf, 1024); // reads from /etc/hosts
+ *
+ *     // If the file descriptor is not stored then it is closed.
+ *     get_file("/etc/login.defs"); // login.defs is closed
+ *
+ *     // Now use fd1 to hold a file descriptor for /etc/passwd.
+ *     fd1 = get_file("/etc/passwd");
+ *
+ *     // The nsAutoRef<nsRawFD> can give up the file descriptor if explicitly
+ *     // instructed, but the caller must then ensure that the file is closed.
+ *     int rawfd = fd1.disown();
+ *
+ *     // Assume ownership of another file descriptor.
+ *     fd1.own(open("/proc/1/maps");
+ *
+ *     // On destruction, fd1 closes /proc/1/maps and fd2 closes /etc/hosts,
+ *     // but /etc/passwd is not closed.
+ * }
+ *
+ */
+
+
+template <class T>
+class nsAutoRef : public nsAutoRefBase<T>
+{
+protected:
+  typedef nsAutoRef<T> ThisClass;
+  typedef nsAutoRefBase<T> BaseClass;
+  typedef nsSimpleRef<T> SimpleRef;
+  typedef typename BaseClass::RawRefOnly RawRefOnly;
+  typedef typename BaseClass::LocalSimpleRef LocalSimpleRef;
+
+public:
+  nsAutoRef()
+  {
+  }
+
+  // Explicit construction is required so as not to risk unintentionally
+  // releasing the resource associated with a raw ref.
+  explicit nsAutoRef(RawRefOnly aRefToRelease)
+    : BaseClass(aRefToRelease)
+  {
+  }
+
+  // Construction from a nsReturnRef<T> function return value, which expects
+  // to give up ownership, transfers ownership.
+  // (nsReturnRef<T> is converted to const nsReturningRef<T>.)
+  explicit nsAutoRef(const nsReturningRef<T>& aReturning)
+    : BaseClass(aReturning)
+  {
+  }
+
+  // The only assignment operator provided is for transferring from an
+  // nsReturnRef smart reference, which expects to pass its ownership to
+  // another object.
+  //
+  // With raw references and other smart references, the type of the lhs and
+  // its taking and releasing nature is often not obvious from an assignment
+  // statement.  Assignment from a raw ptr especially is not normally
+  // expected to release the reference.
+  //
+  // Use |steal| for taking ownership from other smart refs.
+  //
+  // For raw references, use |own| to indicate intention to have the
+  // resource released.
+  //
+  // Or, to create another owner of the same reference, use an nsCountedRef.
+
+  ThisClass& operator=(const nsReturningRef<T>& aReturning)
+  {
+    BaseClass::steal(aReturning.mReturnRef);
+    return *this;
+  }
+
+  // Conversion to a raw reference allow the nsAutoRef<T> to often be used
+  // like a raw reference.
+  operator typename SimpleRef::RawRef() const
+  {
+    return this->get();
+  }
+
+  // Transfer ownership from another smart reference.
+  void steal(ThisClass& aOtherRef)
+  {
+    BaseClass::steal(aOtherRef);
+  }
+
+  // Assume ownership of a raw ref.
+  //
+  // |own| has similar function to |steal|, and is useful for receiving
+  // ownership from a return value of a function.  It is named differently
+  // because |own| requires more care to ensure that the function intends to
+  // give away ownership, and so that |steal| can be safely used, knowing
+  // that it won't steal ownership from any methods returning raw ptrs to
+  // data owned by a foreign object.
+  void own(RawRefOnly aRefToRelease)
+  {
+    BaseClass::own(aRefToRelease);
+  }
+
+  // Exchange ownership with |aOther|
+  void swap(ThisClass& aOther)
+  {
+    LocalSimpleRef temp;
+    temp.SimpleRef::operator=(*this);
+    SimpleRef::operator=(aOther);
+    aOther.SimpleRef::operator=(temp);
+  }
+
+  // Release the reference now.
+  void reset()
+  {
+    this->SafeRelease();
+    LocalSimpleRef empty;
+    SimpleRef::operator=(empty);
+  }
+
+  // Pass out the reference for a function return values.
+  nsReturnRef<T> out()
+  {
+    return nsReturnRef<T>(this->disown());
+  }
+
+  // operator->() and disown() are provided by nsAutoRefBase<T>.
+  // The default nsSimpleRef<T> provides get().
+
+private:
+  // No copy constructor
+  explicit nsAutoRef(ThisClass& aRefToSteal);
+};
+
+/**
+ * template <class T> class nsCountedRef
+ *
+ * A class that creates (adds) a new reference to a resource on construction
+ * or assignment and releases on destruction.
+ *
+ * This class is similar to nsAutoRef<T> and inherits its methods, but also
+ * provides copy construction and assignment operators that enable more than
+ * one concurrent reference to the same resource.
+ *
+ * Specialize |nsAutoRefTraits<T>| or |nsSimpleRef<T>| to use this.  This
+ * class assumes that the resource itself counts references and so can only be
+ * used when |T| represents a reference-counting resource.
+ */
+
+template <class T>
+class nsCountedRef : public nsAutoRef<T>
+{
+protected:
+  typedef nsCountedRef<T> ThisClass;
+  typedef nsAutoRef<T> BaseClass;
+  typedef nsSimpleRef<T> SimpleRef;
+  typedef typename BaseClass::RawRef RawRef;
+
+public:
+  nsCountedRef()
+  {
+  }
+
+  // Construction and assignment from a another nsCountedRef
+  // or a raw ref copies and increments the ref count.
+  nsCountedRef(const ThisClass& aRefToCopy)
+  {
+    SimpleRef::operator=(aRefToCopy);
+    SafeAddRef();
+  }
+  ThisClass& operator=(const ThisClass& aRefToCopy)
+  {
+    if (this == &aRefToCopy) {
+      return *this;
+    }
+
+    this->SafeRelease();
+    SimpleRef::operator=(aRefToCopy);
+    SafeAddRef();
+    return *this;
+  }
+
+  // Implicit conversion from another smart ref argument (to a raw ref) is
+  // accepted here because construction and assignment safely creates a new
+  // reference without interfering with the reference to copy.
+  explicit nsCountedRef(RawRef aRefToCopy)
+    : BaseClass(aRefToCopy)
+  {
+    SafeAddRef();
+  }
+  ThisClass& operator=(RawRef aRefToCopy)
+  {
+    this->own(aRefToCopy);
+    SafeAddRef();
+    return *this;
+  }
+
+  // Construction and assignment from an nsReturnRef function return value,
+  // which expects to give up ownership, transfers ownership.
+  explicit nsCountedRef(const nsReturningRef<T>& aReturning)
+    : BaseClass(aReturning)
+  {
+  }
+  ThisClass& operator=(const nsReturningRef<T>& aReturning)
+  {
+    BaseClass::operator=(aReturning);
+    return *this;
+  }
+
+protected:
+  // Increase the reference count if there is a resource.
+  void SafeAddRef()
+  {
+    if (this->HaveResource()) {
+      this->AddRef(this->get());
+    }
+  }
+};
+
+/**
+ * template <class T> class nsReturnRef
+ *
+ * A type for function return values that hold a reference to a resource that
+ * must be released.  See also |nsAutoRef<T>::out()|.
+ */
+
+template <class T>
+class nsReturnRef : public nsAutoRefBase<T>
+{
+protected:
+  typedef nsAutoRefBase<T> BaseClass;
+  typedef typename BaseClass::RawRefOnly RawRefOnly;
+
+public:
+  // For constructing a return value with no resource
+  nsReturnRef()
+  {
+  }
+
+  // For returning a smart reference from a raw reference that must be
+  // released.  Explicit construction is required so as not to risk
+  // unintentionally releasing the resource associated with a raw ref.
+  MOZ_IMPLICIT nsReturnRef(RawRefOnly aRefToRelease)
+    : BaseClass(aRefToRelease)
+  {
+  }
+
+  // Copy construction transfers ownership
+  nsReturnRef(nsReturnRef<T>& aRefToSteal)
+    : BaseClass(aRefToSteal)
+  {
+  }
+
+  MOZ_IMPLICIT nsReturnRef(const nsReturningRef<T>& aReturning)
+    : BaseClass(aReturning)
+  {
+  }
+
+  // Conversion to a temporary (const) object referring to this object so
+  // that the reference may be passed from a function return value
+  // (temporary) to another smart reference.  There is no need to use this
+  // explicitly.  Simply assign a nsReturnRef<T> function return value to a
+  // smart reference.
+  operator nsReturningRef<T>()
+  {
+    return nsReturningRef<T>(*this);
+  }
+
+  // No conversion to RawRef operator is provided on nsReturnRef, to ensure
+  // that the return value is not carelessly assigned to a raw ptr (and the
+  // resource then released).  If passing to a function that takes a raw
+  // ptr, use get or disown as appropriate.
+};
+
+/**
+ * template <class T> class nsReturningRef
+ *
+ * A class to allow ownership to be transferred from nsReturnRef function
+ * return values.
+ *
+ * It should not be necessary for clients to reference this
+ * class directly.  Simply pass an nsReturnRef<T> to a parameter taking an
+ * |nsReturningRef<T>|.
+ *
+ * The conversion operator on nsReturnRef constructs a temporary wrapper of
+ * class nsReturningRef<T> around a non-const reference to the nsReturnRef.
+ * The wrapper can then be passed as an rvalue parameter.
+ */
+
+template <class T>
+class nsReturningRef
+{
+private:
+  friend class nsReturnRef<T>;
+
+  explicit nsReturningRef(nsReturnRef<T>& aReturnRef)
+    : mReturnRef(aReturnRef)
+  {
+  }
+public:
+  nsReturnRef<T>& mReturnRef;
+};
+
+/**
+ * template <class T> class nsAutoRefTraits
+ *
+ * A class describing traits of references managed by the default
+ * |nsSimpleRef<T>| implementation and thus |nsAutoRef<T>| and |nsCountedRef|.
+ * The default |nsSimpleRef<T> is suitable for resources with handles that
+ * have a void value.  (If there is no such void value for a handle,
+ * specialize |nsSimpleRef<T>|.)
+ *
+ * Specializations must be provided for each class |T| according to the
+ * following pattern:
+ *
+ * // The template parameter |T| should be a class such that the set of fields
+ * // in class nsAutoRefTraits<T> is unique for class |T|.  Usually the
+ * // resource object class is sufficient.  For handles that are simple
+ * // integral typedefs, a new unique possibly-incomplete class may need to be
+ * // declared.
+ *
+ * template <>
+ * class nsAutoRefTraits<T>
+ * {
+ *     // Specializations must provide a typedef for RawRef, describing the
+ *     // type of the handle to the resource.
+ *     typedef <handle-type> RawRef;
+ *
+ *     // Specializations should define Void(), a function returning a value
+ *     // suitable for a handle that does not have an associated resource.
+ *     //
+ *     // The return type must be a suitable as the parameter to a RawRef
+ *     // constructor and operator==.
+ *     //
+ *     // If this method is not accessible then some limited nsAutoRef
+ *     // functionality will still be available, but the default constructor,
+ *     // |reset|, and most transfer of ownership methods will not be available.
+ *     static <return-type> Void();
+ *
+ *     // Specializations must define Release() to properly finalize the
+ *     // handle to a non-void custom-deleted or reference-counted resource.
+ *     static void Release(RawRef aRawRef);
+ *
+ *     // For reference-counted resources, if |nsCountedRef<T>| is to be used,
+ *     // specializations must define AddRef to increment the reference count
+ *     // held by a non-void handle.
+ *     // (AddRef() is not necessary for |nsAutoRef<T>|.)
+ *     static void AddRef(RawRef aRawRef);
+ * };
+ *
+ * See nsPointerRefTraits for example specializations for simple pointer
+ * references.  See nsAutoRef for an example specialization for a non-pointer
+ * reference.
+ */
+
+template <class T> class nsAutoRefTraits;
+
+/**
+ * template <class T> class nsPointerRefTraits
+ *
+ * A convenience class useful as a base class for specializations of
+ * |nsAutoRefTraits<T>| where the handle to the resource is a pointer to |T|.
+ * By inheriting from this class, definitions of only Release(RawRef) and
+ * possibly AddRef(RawRef) need to be added.
+ *
+ * Examples of use:
+ *
+ * template <>
+ * class nsAutoRefTraits<PRFileDesc> : public nsPointerRefTraits<PRFileDesc>
+ * {
+ * public:
+ *     static void Release(PRFileDesc *ptr) { PR_Close(ptr); }
+ * };
+ *
+ * template <>
+ * class nsAutoRefTraits<FcPattern> : public nsPointerRefTraits<FcPattern>
+ * {
+ * public:
+ *     static void Release(FcPattern *ptr) { FcPatternDestroy(ptr); }
+ *     static void AddRef(FcPattern *ptr) { FcPatternReference(ptr); }
+ * };
+ */
+
+template <class T>
+class nsPointerRefTraits
+{
+public:
+  // The handle is a pointer to T.
+  typedef T* RawRef;
+  // A nullptr does not have a resource.
+  static RawRef Void()
+  {
+    return nullptr;
+  }
+};
+
+/**
+ * template <class T> class nsSimpleRef
+ *
+ * Constructs a non-smart reference, and provides methods to test whether
+ * there is an associated resource and (if so) get its raw handle.
+ *
+ * A default implementation is suitable for resources with handles that have a
+ * void value.  This is not intended for direct use but used by |nsAutoRef<T>|
+ * and thus |nsCountedRef<T>|.
+ *
+ * Specialize this class if there is no particular void value for the resource
+ * handle.  A specialized implementation must also provide Release(RawRef),
+ * and, if |nsCountedRef<T>| is required, AddRef(RawRef), as described in
+ * nsAutoRefTraits<T>.
+ */
+
+template <class T>
+class nsSimpleRef : protected nsAutoRefTraits<T>
+{
+protected:
+  // The default implementation uses nsAutoRefTrait<T>.
+  // Specializations need not define this typedef.
+  typedef nsAutoRefTraits<T> Traits;
+  // The type of the handle to the resource.
+  // A specialization must provide a typedef for RawRef.
+  typedef typename Traits::RawRef RawRef;
+
+  // Construct with no resource.
+  //
+  // If this constructor is not accessible then some limited nsAutoRef
+  // functionality will still be available, but the default constructor,
+  // |reset|, and most transfer of ownership methods will not be available.
+  nsSimpleRef()
+    : mRawRef(Traits::Void())
+  {
+  }
+  // Construct with a handle to a resource.
+  // A specialization must provide this.
+  explicit nsSimpleRef(RawRef aRawRef)
+    : mRawRef(aRawRef)
+  {
+  }
+
+  // Test whether there is an associated resource.  A specialization must
+  // provide this.  The function is permitted to always return true if the
+  // default constructor is not accessible, or if Release (and AddRef) can
+  // deal with void handles.
+  bool HaveResource() const
+  {
+    return mRawRef != Traits::Void();
+  }
+
+public:
+  // A specialization must provide get() or loose some functionality.  This
+  // is inherited by derived classes and the specialization may choose
+  // whether it is public or protected.
+  RawRef get() const
+  {
+    return mRawRef;
+  }
+
+private:
+  RawRef mRawRef;
+};
+
+
+/**
+ * template <class T> class nsAutoRefBase
+ *
+ * Internal base class for |nsAutoRef<T>| and |nsReturnRef<T>|.
+ * Adds release on destruction to a |nsSimpleRef<T>|.
+ */
+
+template <class T>
+class nsAutoRefBase : public nsSimpleRef<T>
+{
+protected:
+  typedef nsAutoRefBase<T> ThisClass;
+  typedef nsSimpleRef<T> SimpleRef;
+  typedef typename SimpleRef::RawRef RawRef;
+
+  nsAutoRefBase()
+  {
+  }
+
+  // A type for parameters that should be passed a raw ref but should not
+  // accept implicit conversions (from another smart ref).  (The only
+  // conversion to this type is from a raw ref so only raw refs will be
+  // accepted.)
+  class RawRefOnly
+  {
+  public:
+    MOZ_IMPLICIT RawRefOnly(RawRef aRawRef)
+      : mRawRef(aRawRef)
+    {
+    }
+    operator RawRef() const
+    {
+      return mRawRef;
+    }
+  private:
+    RawRef mRawRef;
+  };
+
+  // Construction from a raw ref assumes ownership
+  explicit nsAutoRefBase(RawRefOnly aRefToRelease)
+    : SimpleRef(aRefToRelease)
+  {
+  }
+
+  // Constructors that steal ownership
+  explicit nsAutoRefBase(ThisClass& aRefToSteal)
+    : SimpleRef(aRefToSteal.disown())
+  {
+  }
+  explicit nsAutoRefBase(const nsReturningRef<T>& aReturning)
+    : SimpleRef(aReturning.mReturnRef.disown())
+  {
+  }
+
+  ~nsAutoRefBase()
+  {
+    SafeRelease();
+  }
+
+  // An internal class providing access to protected nsSimpleRef<T>
+  // constructors for construction of temporary simple references (that are
+  // not ThisClass).
+  class LocalSimpleRef : public SimpleRef
+  {
+  public:
+    LocalSimpleRef()
+    {
+    }
+    explicit LocalSimpleRef(RawRef aRawRef)
+      : SimpleRef(aRawRef)
+    {
+    }
+  };
+
+private:
+  ThisClass& operator=(const ThisClass& aSmartRef) = delete;
+
+public:
+  RawRef operator->() const
+  {
+    return this->get();
+  }
+
+  // Transfer ownership to a raw reference.
+  //
+  // THE CALLER MUST ENSURE THAT THE REFERENCE IS EXPLICITLY RELEASED.
+  //
+  // Is this really what you want to use?  Using this removes any guarantee
+  // of release.  Use nsAutoRef<T>::out() for return values, or an
+  // nsAutoRef<T> modifiable lvalue for an out parameter.  Use disown() when
+  // the reference must be stored in a POD type object, such as may be
+  // preferred for a namespace-scope object with static storage duration,
+  // for example.
+  RawRef disown()
+  {
+    RawRef temp = this->get();
+    LocalSimpleRef empty;
+    SimpleRef::operator=(empty);
+    return temp;
+  }
+
+protected:
+  // steal and own are protected because they make no sense on nsReturnRef,
+  // but steal is implemented on this class for access to aOtherRef.disown()
+  // when aOtherRef is an nsReturnRef;
+
+  // Transfer ownership from another smart reference.
+  void steal(ThisClass& aOtherRef)
+  {
+    own(aOtherRef.disown());
+  }
+  // Assume ownership of a raw ref.
+  void own(RawRefOnly aRefToRelease)
+  {
+    SafeRelease();
+    LocalSimpleRef ref(aRefToRelease);
+    SimpleRef::operator=(ref);
+  }
+
+  // Release a resource if there is one.
+  void SafeRelease()
+  {
+    if (this->HaveResource()) {
+      this->Release(this->get());
+    }
+  }
+};
+
+#endif // !defined(nsAutoRef_h_)
diff --git a/xpcom/base/nsCom.h b/xpcom/base/nsCom.h
new file mode 100644
index 000000000..20353a266
--- /dev/null
+++ b/xpcom/base/nsCom.h
@@ -0,0 +1,12 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCom_h__
+#define nsCom_h__
+#include "nscore.h"
+#endif
+
+
diff --git a/xpcom/base/nsConsoleMessage.cpp b/xpcom/base/nsConsoleMessage.cpp
new file mode 100644
index 000000000..e3530745b
--- /dev/null
+++ b/xpcom/base/nsConsoleMessage.cpp
@@ -0,0 +1,56 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Base implementation for console messages.
+ */
+
+#include "nsConsoleMessage.h"
+#include "jsapi.h"
+
+NS_IMPL_ISUPPORTS(nsConsoleMessage, nsIConsoleMessage)
+
+nsConsoleMessage::nsConsoleMessage()
+  : mTimeStamp(0)
+  , mMessage()
+{
+}
+
+nsConsoleMessage::nsConsoleMessage(const char16_t* aMessage)
+{
+  mTimeStamp = JS_Now() / 1000;
+  mMessage.Assign(aMessage);
+}
+
+NS_IMETHODIMP
+nsConsoleMessage::GetMessageMoz(char16_t** aResult)
+{
+  *aResult = ToNewUnicode(mMessage);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsConsoleMessage::GetLogLevel(uint32_t* aLogLevel)
+{
+  *aLogLevel = nsConsoleMessage::info;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsConsoleMessage::GetTimeStamp(int64_t* aTimeStamp)
+{
+  *aTimeStamp = mTimeStamp;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsConsoleMessage::ToString(nsACString& /*UTF8*/ aResult)
+{
+  CopyUTF16toUTF8(mMessage, aResult);
+
+  return NS_OK;
+}
diff --git a/xpcom/base/nsConsoleMessage.h b/xpcom/base/nsConsoleMessage.h
new file mode 100644
index 000000000..64ad921a5
--- /dev/null
+++ b/xpcom/base/nsConsoleMessage.h
@@ -0,0 +1,33 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __nsconsolemessage_h__
+#define __nsconsolemessage_h__
+
+#include "mozilla/Attributes.h"
+
+#include "nsIConsoleMessage.h"
+#include "nsString.h"
+
+class nsConsoleMessage final : public nsIConsoleMessage
+{
+public:
+  nsConsoleMessage();
+  explicit nsConsoleMessage(const char16_t* aMessage);
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSICONSOLEMESSAGE
+
+private:
+  ~nsConsoleMessage()
+  {
+  }
+
+  int64_t mTimeStamp;
+  nsString mMessage;
+};
+
+#endif /* __nsconsolemessage_h__ */
diff --git a/xpcom/base/nsConsoleService.cpp b/xpcom/base/nsConsoleService.cpp
new file mode 100644
index 000000000..3862a02c4
--- /dev/null
+++ b/xpcom/base/nsConsoleService.cpp
@@ -0,0 +1,473 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Maintains a circular buffer of recent messages, and notifies
+ * listeners when new messages are logged.
+ */
+
+/* Threadsafe. */
+
+#include "nsMemory.h"
+#include "nsCOMArray.h"
+#include "nsThreadUtils.h"
+
+#include "nsConsoleService.h"
+#include "nsConsoleMessage.h"
+#include "nsIClassInfoImpl.h"
+#include "nsIConsoleListener.h"
+#include "nsPrintfCString.h"
+#include "nsProxyRelease.h"
+#include "nsIScriptError.h"
+#include "nsISupportsPrimitives.h"
+
+#include "mozilla/Preferences.h"
+
+#if defined(ANDROID)
+#include <android/log.h>
+#include "mozilla/dom/ContentChild.h"
+#endif
+#ifdef XP_WIN
+#include <windows.h>
+#endif
+
+#ifdef MOZ_TASK_TRACER
+#include "GeckoTaskTracer.h"
+using namespace mozilla::tasktracer;
+#endif
+
+using namespace mozilla;
+
+NS_IMPL_ADDREF(nsConsoleService)
+NS_IMPL_RELEASE(nsConsoleService)
+NS_IMPL_CLASSINFO(nsConsoleService, nullptr,
+                  nsIClassInfo::THREADSAFE | nsIClassInfo::SINGLETON,
+                  NS_CONSOLESERVICE_CID)
+NS_IMPL_QUERY_INTERFACE_CI(nsConsoleService, nsIConsoleService, nsIObserver)
+NS_IMPL_CI_INTERFACE_GETTER(nsConsoleService, nsIConsoleService, nsIObserver)
+
+static bool sLoggingEnabled = true;
+static bool sLoggingBuffered = true;
+#if defined(ANDROID)
+static bool sLoggingLogcat = true;
+#endif // defined(ANDROID)
+
+nsConsoleService::MessageElement::~MessageElement()
+{
+}
+
+nsConsoleService::nsConsoleService()
+  : mCurrentSize(0)
+  , mDeliveringMessage(false)
+  , mLock("nsConsoleService.mLock")
+{
+  // XXX grab this from a pref!
+  // hm, but worry about circularity, bc we want to be able to report
+  // prefs errs...
+  mMaximumSize = 250;
+}
+
+
+void
+nsConsoleService::ClearMessagesForWindowID(const uint64_t innerID)
+{
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+  MutexAutoLock lock(mLock);
+
+  for (MessageElement* e = mMessages.getFirst(); e != nullptr; ) {
+    // Only messages implementing nsIScriptError interface expose the
+    // inner window ID.
+    nsCOMPtr<nsIScriptError> scriptError = do_QueryInterface(e->Get());
+    if (!scriptError) {
+      e = e->getNext();
+      continue;
+    }
+    uint64_t innerWindowID;
+    nsresult rv = scriptError->GetInnerWindowID(&innerWindowID);
+    if (NS_FAILED(rv) || innerWindowID != innerID) {
+      e = e->getNext();
+      continue;
+    }
+
+    MessageElement* next = e->getNext();
+    e->remove();
+    delete e;
+    mCurrentSize--;
+    MOZ_ASSERT(mCurrentSize < mMaximumSize);
+
+    e = next;
+  }
+}
+
+void
+nsConsoleService::ClearMessages()
+{
+  // NB: A lock is not required here as it's only called from |Reset| which
+  //     locks for us and from the dtor.
+  while (!mMessages.isEmpty()) {
+    MessageElement* e = mMessages.popFirst();
+    delete e;
+  }
+  mCurrentSize = 0;
+}
+
+nsConsoleService::~nsConsoleService()
+{
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+
+  ClearMessages();
+}
+
+class AddConsolePrefWatchers : public Runnable
+{
+public:
+  explicit AddConsolePrefWatchers(nsConsoleService* aConsole) : mConsole(aConsole)
+  {
+  }
+
+  NS_IMETHOD Run() override
+  {
+    Preferences::AddBoolVarCache(&sLoggingEnabled, "consoleservice.enabled", true);
+    Preferences::AddBoolVarCache(&sLoggingBuffered, "consoleservice.buffered", true);
+#if defined(ANDROID)
+    Preferences::AddBoolVarCache(&sLoggingLogcat, "consoleservice.logcat", true);
+#endif // defined(ANDROID)
+
+    nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
+    MOZ_ASSERT(obs);
+    obs->AddObserver(mConsole, NS_XPCOM_SHUTDOWN_OBSERVER_ID, false);
+    obs->AddObserver(mConsole, "inner-window-destroyed", false);
+
+    if (!sLoggingBuffered) {
+      mConsole->Reset();
+    }
+    return NS_OK;
+  }
+
+private:
+  RefPtr<nsConsoleService> mConsole;
+};
+
+nsresult
+nsConsoleService::Init()
+{
+  NS_DispatchToMainThread(new AddConsolePrefWatchers(this));
+
+  return NS_OK;
+}
+
+namespace {
+
+class LogMessageRunnable : public Runnable
+{
+public:
+  LogMessageRunnable(nsIConsoleMessage* aMessage, nsConsoleService* aService)
+    : mMessage(aMessage)
+    , mService(aService)
+  { }
+
+  NS_DECL_NSIRUNNABLE
+
+private:
+  nsCOMPtr<nsIConsoleMessage> mMessage;
+  RefPtr<nsConsoleService> mService;
+};
+
+NS_IMETHODIMP
+LogMessageRunnable::Run()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // Snapshot of listeners so that we don't reenter this hash during
+  // enumeration.
+  nsCOMArray<nsIConsoleListener> listeners;
+  mService->CollectCurrentListeners(listeners);
+
+  mService->SetIsDelivering();
+
+  for (int32_t i = 0; i < listeners.Count(); ++i) {
+    listeners[i]->Observe(mMessage);
+  }
+
+  mService->SetDoneDelivering();
+
+  return NS_OK;
+}
+
+} // namespace
+
+// nsIConsoleService methods
+NS_IMETHODIMP
+nsConsoleService::LogMessage(nsIConsoleMessage* aMessage)
+{
+  return LogMessageWithMode(aMessage, OutputToLog);
+}
+
+// This can be called off the main thread.
+nsresult
+nsConsoleService::LogMessageWithMode(nsIConsoleMessage* aMessage,
+                                     nsConsoleService::OutputMode aOutputMode)
+{
+  if (!aMessage) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  if (!sLoggingEnabled) {
+    return NS_OK;
+  }
+
+  if (NS_IsMainThread() && mDeliveringMessage) {
+    nsCString msg;
+    aMessage->ToString(msg);
+    NS_WARNING(nsPrintfCString("Reentrancy error: some client attempted "
+      "to display a message to the console while in a console listener. "
+      "The following message was discarded: \"%s\"", msg.get()).get());
+    return NS_ERROR_FAILURE;
+  }
+
+  RefPtr<LogMessageRunnable> r;
+  nsCOMPtr<nsIConsoleMessage> retiredMessage;
+
+  /*
+   * Lock while updating buffer, and while taking snapshot of
+   * listeners array.
+   */
+  {
+    MutexAutoLock lock(mLock);
+
+#if defined(ANDROID)
+    if (sLoggingLogcat && aOutputMode == OutputToLog) {
+      nsCString msg;
+      aMessage->ToString(msg);
+
+      /** Attempt to use the process name as the log tag. */
+      mozilla::dom::ContentChild* child =
+          mozilla::dom::ContentChild::GetSingleton();
+      nsCString appName;
+      if (child) {
+        child->GetProcessName(appName);
+      } else {
+        appName = "GeckoConsole";
+      }
+
+      uint32_t logLevel = 0;
+      aMessage->GetLogLevel(&logLevel);
+
+      android_LogPriority logPriority = ANDROID_LOG_INFO;
+      switch (logLevel) {
+        case nsIConsoleMessage::debug:
+          logPriority = ANDROID_LOG_DEBUG;
+          break;
+        case nsIConsoleMessage::info:
+          logPriority = ANDROID_LOG_INFO;
+          break;
+        case nsIConsoleMessage::warn:
+          logPriority = ANDROID_LOG_WARN;
+          break;
+        case nsIConsoleMessage::error:
+          logPriority = ANDROID_LOG_ERROR;
+          break;
+      }
+
+      __android_log_print(logPriority, appName.get(), "%s", msg.get());
+    }
+#endif
+#ifdef XP_WIN
+    if (IsDebuggerPresent()) {
+      nsString msg;
+      aMessage->GetMessageMoz(getter_Copies(msg));
+      msg.Append('\n');
+      OutputDebugStringW(msg.get());
+    }
+#endif
+#ifdef MOZ_TASK_TRACER
+    {
+      nsCString msg;
+      aMessage->ToString(msg);
+      int prefixPos = msg.Find(GetJSLabelPrefix());
+      if (prefixPos >= 0) {
+        nsDependentCSubstring submsg(msg, prefixPos);
+        AddLabel("%s", submsg.BeginReading());
+      }
+    }
+#endif
+
+    if (sLoggingBuffered) {
+      MessageElement* e = new MessageElement(aMessage);
+      mMessages.insertBack(e);
+      if (mCurrentSize != mMaximumSize) {
+        mCurrentSize++;
+      } else {
+        MessageElement* p = mMessages.popFirst();
+        MOZ_ASSERT(p);
+        p->swapMessage(retiredMessage);
+        delete p;
+      }
+    }
+
+    if (mListeners.Count() > 0) {
+      r = new LogMessageRunnable(aMessage, this);
+    }
+  }
+
+  if (retiredMessage) {
+    // Release |retiredMessage| on the main thread in case it is an instance of
+    // a mainthread-only class like nsScriptErrorWithStack and we're off the
+    // main thread.
+    NS_ReleaseOnMainThread(retiredMessage.forget());
+  }
+
+  if (r) {
+    // avoid failing in XPCShell tests
+    nsCOMPtr<nsIThread> mainThread = do_GetMainThread();
+    if (mainThread) {
+      NS_DispatchToMainThread(r.forget());
+    }
+  }
+
+  return NS_OK;
+}
+
+void
+nsConsoleService::CollectCurrentListeners(
+  nsCOMArray<nsIConsoleListener>& aListeners)
+{
+  MutexAutoLock lock(mLock);
+  for (auto iter = mListeners.Iter(); !iter.Done(); iter.Next()) {
+    nsIConsoleListener* value = iter.UserData();
+    aListeners.AppendObject(value);
+  }
+}
+
+NS_IMETHODIMP
+nsConsoleService::LogStringMessage(const char16_t* aMessage)
+{
+  if (!sLoggingEnabled) {
+    return NS_OK;
+  }
+
+  RefPtr<nsConsoleMessage> msg(new nsConsoleMessage(aMessage));
+  return this->LogMessage(msg);
+}
+
+NS_IMETHODIMP
+nsConsoleService::GetMessageArray(uint32_t* aCount,
+                                  nsIConsoleMessage*** aMessages)
+{
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+
+  MutexAutoLock lock(mLock);
+
+  if (mMessages.isEmpty()) {
+    /*
+     * Make a 1-length output array so that nobody gets confused,
+     * and return a count of 0.  This should result in a 0-length
+     * array object when called from script.
+     */
+    nsIConsoleMessage** messageArray = (nsIConsoleMessage**)
+      moz_xmalloc(sizeof(nsIConsoleMessage*));
+    *messageArray = nullptr;
+    *aMessages = messageArray;
+    *aCount = 0;
+
+    return NS_OK;
+  }
+
+  MOZ_ASSERT(mCurrentSize <= mMaximumSize);
+  nsIConsoleMessage** messageArray =
+    static_cast<nsIConsoleMessage**>(moz_xmalloc(sizeof(nsIConsoleMessage*)
+                                                 * mCurrentSize));
+
+  uint32_t i = 0;
+  for (MessageElement* e = mMessages.getFirst(); e != nullptr; e = e->getNext()) {
+    nsCOMPtr<nsIConsoleMessage> m = e->Get();
+    m.forget(&messageArray[i]);
+    i++;
+  }
+
+  MOZ_ASSERT(i == mCurrentSize);
+
+  *aCount = i;
+  *aMessages = messageArray;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsConsoleService::RegisterListener(nsIConsoleListener* aListener)
+{
+  if (!NS_IsMainThread()) {
+    NS_ERROR("nsConsoleService::RegisterListener is main thread only.");
+    return NS_ERROR_NOT_SAME_THREAD;
+  }
+
+  nsCOMPtr<nsISupports> canonical = do_QueryInterface(aListener);
+
+  MutexAutoLock lock(mLock);
+  if (mListeners.GetWeak(canonical)) {
+    // Reregistering a listener isn't good
+    return NS_ERROR_FAILURE;
+  }
+  mListeners.Put(canonical, aListener);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsConsoleService::UnregisterListener(nsIConsoleListener* aListener)
+{
+  if (!NS_IsMainThread()) {
+    NS_ERROR("nsConsoleService::UnregisterListener is main thread only.");
+    return NS_ERROR_NOT_SAME_THREAD;
+  }
+
+  nsCOMPtr<nsISupports> canonical = do_QueryInterface(aListener);
+
+  MutexAutoLock lock(mLock);
+
+  if (!mListeners.GetWeak(canonical)) {
+    // Unregistering a listener that was never registered?
+    return NS_ERROR_FAILURE;
+  }
+  mListeners.Remove(canonical);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsConsoleService::Reset()
+{
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+
+  /*
+   * Make sure nobody trips into the buffer while it's being reset
+   */
+  MutexAutoLock lock(mLock);
+
+  ClearMessages();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsConsoleService::Observe(nsISupports* aSubject, const char* aTopic,
+                          const char16_t* aData)
+{
+  if (!strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID)) {
+    // Dump all our messages, in case any are cycle collected.
+    Reset();
+    // We could remove ourselves from the observer service, but it is about to
+    // drop all observers anyways, so why bother.
+  } else if (!strcmp(aTopic, "inner-window-destroyed")) {
+    nsCOMPtr<nsISupportsPRUint64> supportsInt = do_QueryInterface(aSubject);
+    MOZ_ASSERT(supportsInt);
+
+    uint64_t windowId;
+    MOZ_ALWAYS_SUCCEEDS(supportsInt->GetData(&windowId));
+
+    ClearMessagesForWindowID(windowId);
+  } else {
+    MOZ_CRASH();
+  }
+  return NS_OK;
+}
diff --git a/xpcom/base/nsConsoleService.h b/xpcom/base/nsConsoleService.h
new file mode 100644
index 000000000..089de8106
--- /dev/null
+++ b/xpcom/base/nsConsoleService.h
@@ -0,0 +1,118 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * nsConsoleService class declaration.
+ */
+
+#ifndef __nsconsoleservice_h__
+#define __nsconsoleservice_h__
+
+#include "mozilla/Attributes.h"
+#include "mozilla/Mutex.h"
+
+#include "nsInterfaceHashtable.h"
+#include "nsHashKeys.h"
+
+#include "nsIConsoleService.h"
+
+class nsConsoleService final : public nsIConsoleService,
+                               public nsIObserver
+{
+public:
+  nsConsoleService();
+  nsresult Init();
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSICONSOLESERVICE
+  NS_DECL_NSIOBSERVER
+
+  void SetIsDelivering()
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+    MOZ_ASSERT(!mDeliveringMessage);
+    mDeliveringMessage = true;
+  }
+
+  void SetDoneDelivering()
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+    MOZ_ASSERT(mDeliveringMessage);
+    mDeliveringMessage = false;
+  }
+
+  // This is a variant of LogMessage which allows the caller to determine
+  // if the message should be output to an OS-specific log. This is used on
+  // B2G to control whether the message is logged to the android log or not.
+
+  enum OutputMode {
+    SuppressLog,
+    OutputToLog
+  };
+  virtual nsresult LogMessageWithMode(nsIConsoleMessage* aMessage,
+                                      OutputMode aOutputMode);
+
+  typedef nsInterfaceHashtable<nsISupportsHashKey,
+                               nsIConsoleListener> ListenerHash;
+  void CollectCurrentListeners(nsCOMArray<nsIConsoleListener>& aListeners);
+
+private:
+  class MessageElement : public mozilla::LinkedListElement<MessageElement>
+  {
+  public:
+    explicit MessageElement(nsIConsoleMessage* aMessage) : mMessage(aMessage)
+    {}
+
+    nsIConsoleMessage* Get()
+    {
+      return mMessage.get();
+    }
+
+    // Swap directly into an nsCOMPtr to avoid spurious refcount
+    // traffic off the main thread in debug builds from
+    // NSCAP_ASSERT_NO_QUERY_NEEDED().
+    void swapMessage(nsCOMPtr<nsIConsoleMessage>& aRetVal)
+    {
+      mMessage.swap(aRetVal);
+    }
+
+    ~MessageElement();
+
+  private:
+    nsCOMPtr<nsIConsoleMessage> mMessage;
+
+    MessageElement(const MessageElement&) = delete;
+    MessageElement& operator=(const MessageElement&) = delete;
+    MessageElement(MessageElement&&) = delete;
+    MessageElement& operator=(MessageElement&&) = delete;
+  };
+
+  ~nsConsoleService();
+
+  void ClearMessagesForWindowID(const uint64_t innerID);
+  void ClearMessages();
+
+  mozilla::LinkedList<MessageElement> mMessages;
+
+  // The current size of mMessages.
+  uint32_t mCurrentSize;
+
+  // The maximum size of mMessages.
+  uint32_t mMaximumSize;
+
+  // Are we currently delivering a console message on the main thread? If
+  // so, we suppress incoming messages on the main thread only, to avoid
+  // infinite repitition.
+  bool mDeliveringMessage;
+
+  // Listeners to notify whenever a new message is logged.
+  ListenerHash mListeners;
+
+  // To serialize interesting methods.
+  mozilla::Mutex mLock;
+};
+
+#endif /* __nsconsoleservice_h__ */
diff --git a/xpcom/base/nsCrashOnException.cpp b/xpcom/base/nsCrashOnException.cpp
new file mode 100644
index 000000000..0f8042531
--- /dev/null
+++ b/xpcom/base/nsCrashOnException.cpp
@@ -0,0 +1,44 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCrashOnException.h"
+#include "nsCOMPtr.h"
+#include "nsServiceManagerUtils.h"
+
+#ifdef MOZ_CRASHREPORTER
+#include "nsICrashReporter.h"
+#endif
+
+namespace mozilla {
+
+static int
+ReportException(EXCEPTION_POINTERS* aExceptionInfo)
+{
+#ifdef MOZ_CRASHREPORTER
+  nsCOMPtr<nsICrashReporter> cr =
+    do_GetService("@mozilla.org/toolkit/crash-reporter;1");
+  if (cr) {
+    cr->WriteMinidumpForException(aExceptionInfo);
+  }
+#endif
+  return EXCEPTION_EXECUTE_HANDLER;
+}
+
+XPCOM_API(LRESULT)
+CallWindowProcCrashProtected(WNDPROC aWndProc, HWND aHWnd, UINT aMsg,
+                             WPARAM aWParam, LPARAM aLParam)
+{
+  MOZ_SEH_TRY {
+    return aWndProc(aHWnd, aMsg, aWParam, aLParam);
+  }
+  MOZ_SEH_EXCEPT(ReportException(GetExceptionInformation())) {
+    ::TerminateProcess(::GetCurrentProcess(), 253);
+  }
+  return 0; // not reached
+}
+
+}
+
diff --git a/xpcom/base/nsCrashOnException.h b/xpcom/base/nsCrashOnException.h
new file mode 100644
index 000000000..cdf3fdf09
--- /dev/null
+++ b/xpcom/base/nsCrashOnException.h
@@ -0,0 +1,23 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCrashOnException_h
+#define nsCrashOnException_h
+
+#include <nscore.h>
+#include <windows.h>
+
+namespace mozilla {
+
+// Call a given window procedure, and catch any Win32 exceptions raised from it,
+// and report them as crashes.
+XPCOM_API(LRESULT) CallWindowProcCrashProtected(WNDPROC aWndProc, HWND aHWnd,
+                                                UINT aMsg, WPARAM aWParam,
+                                                LPARAM aLParam);
+
+}
+
+#endif
diff --git a/xpcom/base/nsCycleCollector.cpp b/xpcom/base/nsCycleCollector.cpp
new file mode 100644
index 000000000..ca7057628
--- /dev/null
+++ b/xpcom/base/nsCycleCollector.cpp
@@ -0,0 +1,4213 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// This file implements a garbage-cycle collector based on the paper
+//
+//   Concurrent Cycle Collection in Reference Counted Systems
+//   Bacon & Rajan (2001), ECOOP 2001 / Springer LNCS vol 2072
+//
+// We are not using the concurrent or acyclic cases of that paper; so
+// the green, red and orange colors are not used.
+//
+// The collector is based on tracking pointers of four colors:
+//
+// Black nodes are definitely live. If we ever determine a node is
+// black, it's ok to forget about, drop from our records.
+//
+// White nodes are definitely garbage cycles. Once we finish with our
+// scanning, we unlink all the white nodes and expect that by
+// unlinking them they will self-destruct (since a garbage cycle is
+// only keeping itself alive with internal links, by definition).
+//
+// Snow-white is an addition to the original algorithm. Snow-white object
+// has reference count zero and is just waiting for deletion.
+//
+// Grey nodes are being scanned. Nodes that turn grey will turn
+// either black if we determine that they're live, or white if we
+// determine that they're a garbage cycle. After the main collection
+// algorithm there should be no grey nodes.
+//
+// Purple nodes are *candidates* for being scanned. They are nodes we
+// haven't begun scanning yet because they're not old enough, or we're
+// still partway through the algorithm.
+//
+// XPCOM objects participating in garbage-cycle collection are obliged
+// to inform us when they ought to turn purple; that is, when their
+// refcount transitions from N+1 -> N, for nonzero N. Furthermore we
+// require that *after* an XPCOM object has informed us of turning
+// purple, they will tell us when they either transition back to being
+// black (incremented refcount) or are ultimately deleted.
+
+// Incremental cycle collection
+//
+// Beyond the simple state machine required to implement incremental
+// collection, the CC needs to be able to compensate for things the browser
+// is doing during the collection. There are two kinds of problems. For each
+// of these, there are two cases to deal with: purple-buffered C++ objects
+// and JS objects.
+
+// The first problem is that an object in the CC's graph can become garbage.
+// This is bad because the CC touches the objects in its graph at every
+// stage of its operation.
+//
+// All cycle collected C++ objects that die during a cycle collection
+// will end up actually getting deleted by the SnowWhiteKiller. Before
+// the SWK deletes an object, it checks if an ICC is running, and if so,
+// if the object is in the graph. If it is, the CC clears mPointer and
+// mParticipant so it does not point to the raw object any more. Because
+// objects could die any time the CC returns to the mutator, any time the CC
+// accesses a PtrInfo it must perform a null check on mParticipant to
+// ensure the object has not gone away.
+//
+// JS objects don't always run finalizers, so the CC can't remove them from
+// the graph when they die. Fortunately, JS objects can only die during a GC,
+// so if a GC is begun during an ICC, the browser synchronously finishes off
+// the ICC, which clears the entire CC graph. If the GC and CC are scheduled
+// properly, this should be rare.
+//
+// The second problem is that objects in the graph can be changed, say by
+// being addrefed or released, or by having a field updated, after the object
+// has been added to the graph. The problem is that ICC can miss a newly
+// created reference to an object, and end up unlinking an object that is
+// actually alive.
+//
+// The basic idea of the solution, from "An on-the-fly Reference Counting
+// Garbage Collector for Java" by Levanoni and Petrank, is to notice if an
+// object has had an additional reference to it created during the collection,
+// and if so, don't collect it during the current collection. This avoids having
+// to rerun the scan as in Bacon & Rajan 2001.
+//
+// For cycle collected C++ objects, we modify AddRef to place the object in
+// the purple buffer, in addition to Release. Then, in the CC, we treat any
+// objects in the purple buffer as being alive, after graph building has
+// completed. Because they are in the purple buffer, they will be suspected
+// in the next CC, so there's no danger of leaks. This is imprecise, because
+// we will treat as live an object that has been Released but not AddRefed
+// during graph building, but that's probably rare enough that the additional
+// bookkeeping overhead is not worthwhile.
+//
+// For JS objects, the cycle collector is only looking at gray objects. If a
+// gray object is touched during ICC, it will be made black by UnmarkGray.
+// Thus, if a JS object has become black during the ICC, we treat it as live.
+// Merged JS zones have to be handled specially: we scan all zone globals.
+// If any are black, we treat the zone as being black.
+
+
+// Safety
+//
+// An XPCOM object is either scan-safe or scan-unsafe, purple-safe or
+// purple-unsafe.
+//
+// An nsISupports object is scan-safe if:
+//
+//  - It can be QI'ed to |nsXPCOMCycleCollectionParticipant|, though
+//    this operation loses ISupports identity (like nsIClassInfo).
+//  - Additionally, the operation |traverse| on the resulting
+//    nsXPCOMCycleCollectionParticipant does not cause *any* refcount
+//    adjustment to occur (no AddRef / Release calls).
+//
+// A non-nsISupports ("native") object is scan-safe by explicitly
+// providing its nsCycleCollectionParticipant.
+//
+// An object is purple-safe if it satisfies the following properties:
+//
+//  - The object is scan-safe.
+//
+// When we receive a pointer |ptr| via
+// |nsCycleCollector::suspect(ptr)|, we assume it is purple-safe. We
+// can check the scan-safety, but have no way to ensure the
+// purple-safety; objects must obey, or else the entire system falls
+// apart. Don't involve an object in this scheme if you can't
+// guarantee its purple-safety. The easiest way to ensure that an
+// object is purple-safe is to use nsCycleCollectingAutoRefCnt.
+//
+// When we have a scannable set of purple nodes ready, we begin
+// our walks. During the walks, the nodes we |traverse| should only
+// feed us more scan-safe nodes, and should not adjust the refcounts
+// of those nodes.
+//
+// We do not |AddRef| or |Release| any objects during scanning. We
+// rely on the purple-safety of the roots that call |suspect| to
+// hold, such that we will clear the pointer from the purple buffer
+// entry to the object before it is destroyed. The pointers that are
+// merely scan-safe we hold only for the duration of scanning, and
+// there should be no objects released from the scan-safe set during
+// the scan.
+//
+// We *do* call |Root| and |Unroot| on every white object, on
+// either side of the calls to |Unlink|. This keeps the set of white
+// objects alive during the unlinking.
+//
+
+#if !defined(__MINGW32__)
+#ifdef WIN32
+#include <crtdbg.h>
+#include <errno.h>
+#endif
+#endif
+
+#include "base/process_util.h"
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/AutoRestore.h"
+#include "mozilla/CycleCollectedJSContext.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/HoldDropJSObjects.h"
+/* This must occur *after* base/process_util.h to avoid typedefs conflicts. */
+#include "mozilla/LinkedList.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/SegmentedVector.h"
+
+#include "nsCycleCollectionParticipant.h"
+#include "nsCycleCollectionNoteRootCallback.h"
+#include "nsDeque.h"
+#include "nsCycleCollector.h"
+#include "nsThreadUtils.h"
+#include "nsXULAppAPI.h"
+#include "prenv.h"
+#include "nsPrintfCString.h"
+#include "nsTArray.h"
+#include "nsIConsoleService.h"
+#include "mozilla/Attributes.h"
+#include "nsICycleCollectorListener.h"
+#include "nsIMemoryReporter.h"
+#include "nsIFile.h"
+#include "nsDumpUtils.h"
+#include "xpcpublic.h"
+#include "GeckoProfiler.h"
+#include <stdint.h>
+#include <stdio.h>
+
+#include "mozilla/AutoGlobalTimelineMarker.h"
+#include "mozilla/Likely.h"
+#include "mozilla/PoisonIOInterposer.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/ThreadLocal.h"
+
+#ifdef MOZ_CRASHREPORTER
+#include "nsExceptionHandler.h"
+#endif
+
+using namespace mozilla;
+
+//#define COLLECT_TIME_DEBUG
+
+// Enable assertions that are useful for diagnosing errors in graph construction.
+//#define DEBUG_CC_GRAPH
+
+#define DEFAULT_SHUTDOWN_COLLECTIONS 5
+
+// One to do the freeing, then another to detect there is no more work to do.
+#define NORMAL_SHUTDOWN_COLLECTIONS 2
+
+// Cycle collector environment variables
+//
+// MOZ_CC_LOG_ALL: If defined, always log cycle collector heaps.
+//
+// MOZ_CC_LOG_SHUTDOWN: If defined, log cycle collector heaps at shutdown.
+//
+// MOZ_CC_LOG_THREAD: If set to "main", only automatically log main thread
+// CCs. If set to "worker", only automatically log worker CCs. If set to "all",
+// log either. The default value is "all". This must be used with either
+// MOZ_CC_LOG_ALL or MOZ_CC_LOG_SHUTDOWN for it to do anything.
+//
+// MOZ_CC_LOG_PROCESS: If set to "main", only automatically log main process
+// CCs. If set to "content", only automatically log tab CCs. If set to
+// "plugins", only automatically log plugin CCs. If set to "all", log
+// everything. The default value is "all". This must be used with either
+// MOZ_CC_LOG_ALL or MOZ_CC_LOG_SHUTDOWN for it to do anything.
+//
+// MOZ_CC_ALL_TRACES: If set to "all", any cycle collector
+// logging done will be WantAllTraces, which disables
+// various cycle collector optimizations to give a fuller picture of
+// the heap. If set to "shutdown", only shutdown logging will be WantAllTraces.
+// The default is none.
+//
+// MOZ_CC_RUN_DURING_SHUTDOWN: In non-DEBUG or builds, if this is set,
+// run cycle collections at shutdown.
+//
+// MOZ_CC_LOG_DIRECTORY: The directory in which logs are placed (such as
+// logs from MOZ_CC_LOG_ALL and MOZ_CC_LOG_SHUTDOWN, or other uses
+// of nsICycleCollectorListener)
+
+// Various parameters of this collector can be tuned using environment
+// variables.
+
+struct nsCycleCollectorParams
+{
+  bool mLogAll;
+  bool mLogShutdown;
+  bool mAllTracesAll;
+  bool mAllTracesShutdown;
+  bool mLogThisThread;
+
+  nsCycleCollectorParams() :
+    mLogAll(PR_GetEnv("MOZ_CC_LOG_ALL") != nullptr),
+    mLogShutdown(PR_GetEnv("MOZ_CC_LOG_SHUTDOWN") != nullptr),
+    mAllTracesAll(false),
+    mAllTracesShutdown(false)
+  {
+    const char* logThreadEnv = PR_GetEnv("MOZ_CC_LOG_THREAD");
+    bool threadLogging = true;
+    if (logThreadEnv && !!strcmp(logThreadEnv, "all")) {
+      if (NS_IsMainThread()) {
+        threadLogging = !strcmp(logThreadEnv, "main");
+      } else {
+        threadLogging = !strcmp(logThreadEnv, "worker");
+      }
+    }
+
+    const char* logProcessEnv = PR_GetEnv("MOZ_CC_LOG_PROCESS");
+    bool processLogging = true;
+    if (logProcessEnv && !!strcmp(logProcessEnv, "all")) {
+      switch (XRE_GetProcessType()) {
+        case GeckoProcessType_Default:
+          processLogging = !strcmp(logProcessEnv, "main");
+          break;
+        case GeckoProcessType_Plugin:
+          processLogging = !strcmp(logProcessEnv, "plugins");
+          break;
+        case GeckoProcessType_Content:
+          processLogging = !strcmp(logProcessEnv, "content");
+          break;
+        default:
+          processLogging = false;
+          break;
+      }
+    }
+    mLogThisThread = threadLogging && processLogging;
+
+    const char* allTracesEnv = PR_GetEnv("MOZ_CC_ALL_TRACES");
+    if (allTracesEnv) {
+      if (!strcmp(allTracesEnv, "all")) {
+        mAllTracesAll = true;
+      } else if (!strcmp(allTracesEnv, "shutdown")) {
+        mAllTracesShutdown = true;
+      }
+    }
+  }
+
+  bool LogThisCC(bool aIsShutdown)
+  {
+    return (mLogAll || (aIsShutdown && mLogShutdown)) && mLogThisThread;
+  }
+
+  bool AllTracesThisCC(bool aIsShutdown)
+  {
+    return mAllTracesAll || (aIsShutdown && mAllTracesShutdown);
+  }
+};
+
+#ifdef COLLECT_TIME_DEBUG
+class TimeLog
+{
+public:
+  TimeLog() : mLastCheckpoint(TimeStamp::Now())
+  {
+  }
+
+  void
+  Checkpoint(const char* aEvent)
+  {
+    TimeStamp now = TimeStamp::Now();
+    double dur = (now - mLastCheckpoint).ToMilliseconds();
+    if (dur >= 0.5) {
+      printf("cc: %s took %.1fms\n", aEvent, dur);
+    }
+    mLastCheckpoint = now;
+  }
+
+private:
+  TimeStamp mLastCheckpoint;
+};
+#else
+class TimeLog
+{
+public:
+  TimeLog()
+  {
+  }
+  void Checkpoint(const char* aEvent)
+  {
+  }
+};
+#endif
+
+
+////////////////////////////////////////////////////////////////////////
+// Base types
+////////////////////////////////////////////////////////////////////////
+
+struct PtrInfo;
+
+class EdgePool
+{
+public:
+  // EdgePool allocates arrays of void*, primarily to hold PtrInfo*.
+  // However, at the end of a block, the last two pointers are a null
+  // and then a void** pointing to the next block.  This allows
+  // EdgePool::Iterators to be a single word but still capable of crossing
+  // block boundaries.
+
+  EdgePool()
+  {
+    mSentinelAndBlocks[0].block = nullptr;
+    mSentinelAndBlocks[1].block = nullptr;
+  }
+
+  ~EdgePool()
+  {
+    MOZ_ASSERT(!mSentinelAndBlocks[0].block &&
+               !mSentinelAndBlocks[1].block,
+               "Didn't call Clear()?");
+  }
+
+  void Clear()
+  {
+    EdgeBlock* b = EdgeBlocks();
+    while (b) {
+      EdgeBlock* next = b->Next();
+      delete b;
+      b = next;
+    }
+
+    mSentinelAndBlocks[0].block = nullptr;
+    mSentinelAndBlocks[1].block = nullptr;
+  }
+
+#ifdef DEBUG
+  bool IsEmpty()
+  {
+    return !mSentinelAndBlocks[0].block &&
+           !mSentinelAndBlocks[1].block;
+  }
+#endif
+
+private:
+  struct EdgeBlock;
+  union PtrInfoOrBlock
+  {
+    // Use a union to avoid reinterpret_cast and the ensuing
+    // potential aliasing bugs.
+    PtrInfo* ptrInfo;
+    EdgeBlock* block;
+  };
+  struct EdgeBlock
+  {
+    enum { EdgeBlockSize = 16 * 1024 };
+
+    PtrInfoOrBlock mPointers[EdgeBlockSize];
+    EdgeBlock()
+    {
+      mPointers[EdgeBlockSize - 2].block = nullptr; // sentinel
+      mPointers[EdgeBlockSize - 1].block = nullptr; // next block pointer
+    }
+    EdgeBlock*& Next()
+    {
+      return mPointers[EdgeBlockSize - 1].block;
+    }
+    PtrInfoOrBlock* Start()
+    {
+      return &mPointers[0];
+    }
+    PtrInfoOrBlock* End()
+    {
+      return &mPointers[EdgeBlockSize - 2];
+    }
+  };
+
+  // Store the null sentinel so that we can have valid iterators
+  // before adding any edges and without adding any blocks.
+  PtrInfoOrBlock mSentinelAndBlocks[2];
+
+  EdgeBlock*& EdgeBlocks()
+  {
+    return mSentinelAndBlocks[1].block;
+  }
+  EdgeBlock* EdgeBlocks() const
+  {
+    return mSentinelAndBlocks[1].block;
+  }
+
+public:
+  class Iterator
+  {
+  public:
+    Iterator() : mPointer(nullptr) {}
+    explicit Iterator(PtrInfoOrBlock* aPointer) : mPointer(aPointer) {}
+    Iterator(const Iterator& aOther) : mPointer(aOther.mPointer) {}
+
+    Iterator& operator++()
+    {
+      if (!mPointer->ptrInfo) {
+        // Null pointer is a sentinel for link to the next block.
+        mPointer = (mPointer + 1)->block->mPointers;
+      }
+      ++mPointer;
+      return *this;
+    }
+
+    PtrInfo* operator*() const
+    {
+      if (!mPointer->ptrInfo) {
+        // Null pointer is a sentinel for link to the next block.
+        return (mPointer + 1)->block->mPointers->ptrInfo;
+      }
+      return mPointer->ptrInfo;
+    }
+    bool operator==(const Iterator& aOther) const
+    {
+      return mPointer == aOther.mPointer;
+    }
+    bool operator!=(const Iterator& aOther) const
+    {
+      return mPointer != aOther.mPointer;
+    }
+
+#ifdef DEBUG_CC_GRAPH
+    bool Initialized() const
+    {
+      return mPointer != nullptr;
+    }
+#endif
+
+  private:
+    PtrInfoOrBlock* mPointer;
+  };
+
+  class Builder;
+  friend class Builder;
+  class Builder
+  {
+  public:
+    explicit Builder(EdgePool& aPool)
+      : mCurrent(&aPool.mSentinelAndBlocks[0])
+      , mBlockEnd(&aPool.mSentinelAndBlocks[0])
+      , mNextBlockPtr(&aPool.EdgeBlocks())
+    {
+    }
+
+    Iterator Mark()
+    {
+      return Iterator(mCurrent);
+    }
+
+    void Add(PtrInfo* aEdge)
+    {
+      if (mCurrent == mBlockEnd) {
+        EdgeBlock* b = new EdgeBlock();
+        *mNextBlockPtr = b;
+        mCurrent = b->Start();
+        mBlockEnd = b->End();
+        mNextBlockPtr = &b->Next();
+      }
+      (mCurrent++)->ptrInfo = aEdge;
+    }
+  private:
+    // mBlockEnd points to space for null sentinel
+    PtrInfoOrBlock* mCurrent;
+    PtrInfoOrBlock* mBlockEnd;
+    EdgeBlock** mNextBlockPtr;
+  };
+
+  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
+  {
+    size_t n = 0;
+    EdgeBlock* b = EdgeBlocks();
+    while (b) {
+      n += aMallocSizeOf(b);
+      b = b->Next();
+    }
+    return n;
+  }
+};
+
+#ifdef DEBUG_CC_GRAPH
+#define CC_GRAPH_ASSERT(b) MOZ_ASSERT(b)
+#else
+#define CC_GRAPH_ASSERT(b)
+#endif
+
+#define CC_TELEMETRY(_name, _value)                                            \
+    PR_BEGIN_MACRO                                                             \
+    if (NS_IsMainThread()) {                                                   \
+      Telemetry::Accumulate(Telemetry::CYCLE_COLLECTOR##_name, _value);        \
+    } else {                                                                   \
+      Telemetry::Accumulate(Telemetry::CYCLE_COLLECTOR_WORKER##_name, _value); \
+    }                                                                          \
+    PR_END_MACRO
+
+enum NodeColor { black, white, grey };
+
+// This structure should be kept as small as possible; we may expect
+// hundreds of thousands of them to be allocated and touched
+// repeatedly during each cycle collection.
+
+struct PtrInfo
+{
+  void* mPointer;
+  nsCycleCollectionParticipant* mParticipant;
+  uint32_t mColor : 2;
+  uint32_t mInternalRefs : 30;
+  uint32_t mRefCount;
+private:
+  EdgePool::Iterator mFirstChild;
+
+  static const uint32_t kInitialRefCount = UINT32_MAX - 1;
+
+public:
+
+  PtrInfo(void* aPointer, nsCycleCollectionParticipant* aParticipant)
+    : mPointer(aPointer),
+      mParticipant(aParticipant),
+      mColor(grey),
+      mInternalRefs(0),
+      mRefCount(kInitialRefCount),
+      mFirstChild()
+  {
+    MOZ_ASSERT(aParticipant);
+
+    // We initialize mRefCount to a large non-zero value so
+    // that it doesn't look like a JS object to the cycle collector
+    // in the case where the object dies before being traversed.
+    MOZ_ASSERT(!IsGrayJS() && !IsBlackJS());
+  }
+
+  // Allow NodePool::NodeBlock's constructor to compile.
+  PtrInfo()
+  {
+    NS_NOTREACHED("should never be called");
+  }
+
+  bool IsGrayJS() const
+  {
+    return mRefCount == 0;
+  }
+
+  bool IsBlackJS() const
+  {
+    return mRefCount == UINT32_MAX;
+  }
+
+  bool WasTraversed() const
+  {
+    return mRefCount != kInitialRefCount;
+  }
+
+  EdgePool::Iterator FirstChild() const
+  {
+    CC_GRAPH_ASSERT(mFirstChild.Initialized());
+    return mFirstChild;
+  }
+
+  // this PtrInfo must be part of a NodePool
+  EdgePool::Iterator LastChild() const
+  {
+    CC_GRAPH_ASSERT((this + 1)->mFirstChild.Initialized());
+    return (this + 1)->mFirstChild;
+  }
+
+  void SetFirstChild(EdgePool::Iterator aFirstChild)
+  {
+    CC_GRAPH_ASSERT(aFirstChild.Initialized());
+    mFirstChild = aFirstChild;
+  }
+
+  // this PtrInfo must be part of a NodePool
+  void SetLastChild(EdgePool::Iterator aLastChild)
+  {
+    CC_GRAPH_ASSERT(aLastChild.Initialized());
+    (this + 1)->mFirstChild = aLastChild;
+  }
+};
+
+/**
+ * A structure designed to be used like a linked list of PtrInfo, except
+ * it allocates many PtrInfos at a time.
+ */
+class NodePool
+{
+private:
+  // The -2 allows us to use |NodeBlockSize + 1| for |mEntries|, and fit
+  // |mNext|, all without causing slop.
+  enum { NodeBlockSize = 4 * 1024 - 2 };
+
+  struct NodeBlock
+  {
+    // We create and destroy NodeBlock using moz_xmalloc/free rather than new
+    // and delete to avoid calling its constructor and destructor.
+    NodeBlock()
+    {
+      NS_NOTREACHED("should never be called");
+
+      // Ensure NodeBlock is the right size (see the comment on NodeBlockSize
+      // above).
+      static_assert(
+        sizeof(NodeBlock) ==  81904 ||  // 32-bit; equals 19.996 x 4 KiB pages
+        sizeof(NodeBlock) == 131048,    // 64-bit; equals 31.994 x 4 KiB pages
+        "ill-sized NodeBlock"
+      );
+    }
+    ~NodeBlock()
+    {
+      NS_NOTREACHED("should never be called");
+    }
+
+    NodeBlock* mNext;
+    PtrInfo mEntries[NodeBlockSize + 1]; // +1 to store last child of last node
+  };
+
+public:
+  NodePool()
+    : mBlocks(nullptr)
+    , mLast(nullptr)
+  {
+  }
+
+  ~NodePool()
+  {
+    MOZ_ASSERT(!mBlocks, "Didn't call Clear()?");
+  }
+
+  void Clear()
+  {
+    NodeBlock* b = mBlocks;
+    while (b) {
+      NodeBlock* n = b->mNext;
+      free(b);
+      b = n;
+    }
+
+    mBlocks = nullptr;
+    mLast = nullptr;
+  }
+
+#ifdef DEBUG
+  bool IsEmpty()
+  {
+    return !mBlocks && !mLast;
+  }
+#endif
+
+  class Builder;
+  friend class Builder;
+  class Builder
+  {
+  public:
+    explicit Builder(NodePool& aPool)
+      : mNextBlock(&aPool.mBlocks)
+      , mNext(aPool.mLast)
+      , mBlockEnd(nullptr)
+    {
+      MOZ_ASSERT(!aPool.mBlocks && !aPool.mLast, "pool not empty");
+    }
+    PtrInfo* Add(void* aPointer, nsCycleCollectionParticipant* aParticipant)
+    {
+      if (mNext == mBlockEnd) {
+        NodeBlock* block = static_cast<NodeBlock*>(malloc(sizeof(NodeBlock)));
+        if (!block) {
+          return nullptr;
+        }
+
+        *mNextBlock = block;
+        mNext = block->mEntries;
+        mBlockEnd = block->mEntries + NodeBlockSize;
+        block->mNext = nullptr;
+        mNextBlock = &block->mNext;
+      }
+      return new (mozilla::KnownNotNull, mNext++) PtrInfo(aPointer, aParticipant);
+    }
+  private:
+    NodeBlock** mNextBlock;
+    PtrInfo*& mNext;
+    PtrInfo* mBlockEnd;
+  };
+
+  class Enumerator;
+  friend class Enumerator;
+  class Enumerator
+  {
+  public:
+    explicit Enumerator(NodePool& aPool)
+      : mFirstBlock(aPool.mBlocks)
+      , mCurBlock(nullptr)
+      , mNext(nullptr)
+      , mBlockEnd(nullptr)
+      , mLast(aPool.mLast)
+    {
+    }
+
+    bool IsDone() const
+    {
+      return mNext == mLast;
+    }
+
+    bool AtBlockEnd() const
+    {
+      return mNext == mBlockEnd;
+    }
+
+    PtrInfo* GetNext()
+    {
+      MOZ_ASSERT(!IsDone(), "calling GetNext when done");
+      if (mNext == mBlockEnd) {
+        NodeBlock* nextBlock = mCurBlock ? mCurBlock->mNext : mFirstBlock;
+        mNext = nextBlock->mEntries;
+        mBlockEnd = mNext + NodeBlockSize;
+        mCurBlock = nextBlock;
+      }
+      return mNext++;
+    }
+  private:
+    // mFirstBlock is a reference to allow an Enumerator to be constructed
+    // for an empty graph.
+    NodeBlock*& mFirstBlock;
+    NodeBlock* mCurBlock;
+    // mNext is the next value we want to return, unless mNext == mBlockEnd
+    // NB: mLast is a reference to allow enumerating while building!
+    PtrInfo* mNext;
+    PtrInfo* mBlockEnd;
+    PtrInfo*& mLast;
+  };
+
+  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
+  {
+    // We don't measure the things pointed to by mEntries[] because those
+    // pointers are non-owning.
+    size_t n = 0;
+    NodeBlock* b = mBlocks;
+    while (b) {
+      n += aMallocSizeOf(b);
+      b = b->mNext;
+    }
+    return n;
+  }
+
+private:
+  NodeBlock* mBlocks;
+  PtrInfo* mLast;
+};
+
+
+// Declarations for mPtrToNodeMap.
+
+struct PtrToNodeEntry : public PLDHashEntryHdr
+{
+  // The key is mNode->mPointer
+  PtrInfo* mNode;
+};
+
+static bool
+PtrToNodeMatchEntry(const PLDHashEntryHdr* aEntry, const void* aKey)
+{
+  const PtrToNodeEntry* n = static_cast<const PtrToNodeEntry*>(aEntry);
+  return n->mNode->mPointer == aKey;
+}
+
+static PLDHashTableOps PtrNodeOps = {
+  PLDHashTable::HashVoidPtrKeyStub,
+  PtrToNodeMatchEntry,
+  PLDHashTable::MoveEntryStub,
+  PLDHashTable::ClearEntryStub,
+  nullptr
+};
+
+
+struct WeakMapping
+{
+  // map and key will be null if the corresponding objects are GC marked
+  PtrInfo* mMap;
+  PtrInfo* mKey;
+  PtrInfo* mKeyDelegate;
+  PtrInfo* mVal;
+};
+
+class CCGraphBuilder;
+
+struct CCGraph
+{
+  NodePool mNodes;
+  EdgePool mEdges;
+  nsTArray<WeakMapping> mWeakMaps;
+  uint32_t mRootCount;
+
+private:
+  PLDHashTable mPtrToNodeMap;
+  bool mOutOfMemory;
+
+  static const uint32_t kInitialMapLength = 16384;
+
+public:
+  CCGraph()
+    : mRootCount(0)
+    , mPtrToNodeMap(&PtrNodeOps, sizeof(PtrToNodeEntry), kInitialMapLength)
+    , mOutOfMemory(false)
+  {}
+
+  ~CCGraph() {}
+
+  void Init()
+  {
+    MOZ_ASSERT(IsEmpty(), "Failed to call CCGraph::Clear");
+  }
+
+  void Clear()
+  {
+    mNodes.Clear();
+    mEdges.Clear();
+    mWeakMaps.Clear();
+    mRootCount = 0;
+    mPtrToNodeMap.ClearAndPrepareForLength(kInitialMapLength);
+    mOutOfMemory = false;
+  }
+
+#ifdef DEBUG
+  bool IsEmpty()
+  {
+    return mNodes.IsEmpty() && mEdges.IsEmpty() &&
+           mWeakMaps.IsEmpty() && mRootCount == 0 &&
+           mPtrToNodeMap.EntryCount() == 0;
+  }
+#endif
+
+  PtrInfo* FindNode(void* aPtr);
+  PtrToNodeEntry* AddNodeToMap(void* aPtr);
+  void RemoveObjectFromMap(void* aObject);
+
+  uint32_t MapCount() const
+  {
+    return mPtrToNodeMap.EntryCount();
+  }
+
+  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
+  {
+    size_t n = 0;
+
+    n += mNodes.SizeOfExcludingThis(aMallocSizeOf);
+    n += mEdges.SizeOfExcludingThis(aMallocSizeOf);
+
+    // We don't measure what the WeakMappings point to, because the
+    // pointers are non-owning.
+    n += mWeakMaps.ShallowSizeOfExcludingThis(aMallocSizeOf);
+
+    n += mPtrToNodeMap.ShallowSizeOfExcludingThis(aMallocSizeOf);
+
+    return n;
+  }
+
+private:
+  PtrToNodeEntry* FindNodeEntry(void* aPtr)
+  {
+    return static_cast<PtrToNodeEntry*>(mPtrToNodeMap.Search(aPtr));
+  }
+};
+
+PtrInfo*
+CCGraph::FindNode(void* aPtr)
+{
+  PtrToNodeEntry* e = FindNodeEntry(aPtr);
+  return e ? e->mNode : nullptr;
+}
+
+PtrToNodeEntry*
+CCGraph::AddNodeToMap(void* aPtr)
+{
+  JS::AutoSuppressGCAnalysis suppress;
+  if (mOutOfMemory) {
+    return nullptr;
+  }
+
+  auto e = static_cast<PtrToNodeEntry*>(mPtrToNodeMap.Add(aPtr, fallible));
+  if (!e) {
+    mOutOfMemory = true;
+    MOZ_ASSERT(false, "Ran out of memory while building cycle collector graph");
+    return nullptr;
+  }
+  return e;
+}
+
+void
+CCGraph::RemoveObjectFromMap(void* aObj)
+{
+  PtrToNodeEntry* e = FindNodeEntry(aObj);
+  PtrInfo* pinfo = e ? e->mNode : nullptr;
+  if (pinfo) {
+    mPtrToNodeMap.RemoveEntry(e);
+
+    pinfo->mPointer = nullptr;
+    pinfo->mParticipant = nullptr;
+  }
+}
+
+
+static nsISupports*
+CanonicalizeXPCOMParticipant(nsISupports* aIn)
+{
+  nsISupports* out = nullptr;
+  aIn->QueryInterface(NS_GET_IID(nsCycleCollectionISupports),
+                      reinterpret_cast<void**>(&out));
+  return out;
+}
+
+static inline void
+ToParticipant(nsISupports* aPtr, nsXPCOMCycleCollectionParticipant** aCp);
+
+static void
+CanonicalizeParticipant(void** aParti, nsCycleCollectionParticipant** aCp)
+{
+  // If the participant is null, this is an nsISupports participant,
+  // so we must QI to get the real participant.
+
+  if (!*aCp) {
+    nsISupports* nsparti = static_cast<nsISupports*>(*aParti);
+    nsparti = CanonicalizeXPCOMParticipant(nsparti);
+    NS_ASSERTION(nsparti,
+                 "Don't add objects that don't participate in collection!");
+    nsXPCOMCycleCollectionParticipant* xcp;
+    ToParticipant(nsparti, &xcp);
+    *aParti = nsparti;
+    *aCp = xcp;
+  }
+}
+
+struct nsPurpleBufferEntry
+{
+  union
+  {
+    void* mObject;                        // when low bit unset
+    nsPurpleBufferEntry* mNextInFreeList; // when low bit set
+  };
+
+  nsCycleCollectingAutoRefCnt* mRefCnt;
+
+  nsCycleCollectionParticipant* mParticipant; // nullptr for nsISupports
+};
+
+class nsCycleCollector;
+
+struct nsPurpleBuffer
+{
+private:
+  struct PurpleBlock
+  {
+    PurpleBlock* mNext;
+    // Try to match the size of a jemalloc bucket, to minimize slop bytes.
+    // - On 32-bit platforms sizeof(nsPurpleBufferEntry) is 12, so mEntries
+    //   is 16,380 bytes, which leaves 4 bytes for mNext.
+    // - On 64-bit platforms sizeof(nsPurpleBufferEntry) is 24, so mEntries
+    //   is 32,544 bytes, which leaves 8 bytes for mNext.
+    nsPurpleBufferEntry mEntries[1365];
+
+    PurpleBlock() : mNext(nullptr)
+    {
+      // Ensure PurpleBlock is the right size (see above).
+      static_assert(
+        sizeof(PurpleBlock) == 16384 ||       // 32-bit
+        sizeof(PurpleBlock) == 32768,         // 64-bit
+        "ill-sized nsPurpleBuffer::PurpleBlock"
+      );
+
+      InitNextPointers();
+    }
+
+    // Put all the entries in the block on the free list.
+    void InitNextPointers()
+    {
+      for (uint32_t i = 1; i < ArrayLength(mEntries); ++i) {
+        mEntries[i - 1].mNextInFreeList =
+          (nsPurpleBufferEntry*)(uintptr_t(mEntries + i) | 1);
+      }
+      mEntries[ArrayLength(mEntries) - 1].mNextInFreeList =
+        (nsPurpleBufferEntry*)1;
+    }
+
+    template<class PurpleVisitor>
+    void VisitEntries(nsPurpleBuffer& aBuffer, PurpleVisitor& aVisitor)
+    {
+      nsPurpleBufferEntry* eEnd = ArrayEnd(mEntries);
+      for (nsPurpleBufferEntry* e = mEntries; e != eEnd; ++e) {
+        MOZ_ASSERT(e->mObject, "There should be no null mObject when we iterate over the purple buffer");
+        if (!(uintptr_t(e->mObject) & uintptr_t(1)) && e->mObject) {
+          aVisitor.Visit(aBuffer, e);
+        }
+      }
+    }
+  };
+  // This class wraps a linked list of the elements in the purple
+  // buffer.
+
+  uint32_t mCount;
+  PurpleBlock mFirstBlock;
+  nsPurpleBufferEntry* mFreeList;
+
+public:
+  nsPurpleBuffer()
+  {
+    InitBlocks();
+  }
+
+  ~nsPurpleBuffer()
+  {
+    FreeBlocks();
+  }
+
+  template<class PurpleVisitor>
+  void VisitEntries(PurpleVisitor& aVisitor)
+  {
+    for (PurpleBlock* b = &mFirstBlock; b; b = b->mNext) {
+      b->VisitEntries(*this, aVisitor);
+    }
+  }
+
+  void InitBlocks()
+  {
+    mCount = 0;
+    mFreeList = mFirstBlock.mEntries;
+  }
+
+  void FreeBlocks()
+  {
+    if (mCount > 0) {
+      UnmarkRemainingPurple(&mFirstBlock);
+    }
+    PurpleBlock* b = mFirstBlock.mNext;
+    while (b) {
+      if (mCount > 0) {
+        UnmarkRemainingPurple(b);
+      }
+      PurpleBlock* next = b->mNext;
+      delete b;
+      b = next;
+    }
+    mFirstBlock.mNext = nullptr;
+  }
+
+  struct UnmarkRemainingPurpleVisitor
+  {
+    void
+    Visit(nsPurpleBuffer& aBuffer, nsPurpleBufferEntry* aEntry)
+    {
+      if (aEntry->mRefCnt) {
+        aEntry->mRefCnt->RemoveFromPurpleBuffer();
+        aEntry->mRefCnt = nullptr;
+      }
+      aEntry->mObject = nullptr;
+      --aBuffer.mCount;
+    }
+  };
+
+  void UnmarkRemainingPurple(PurpleBlock* aBlock)
+  {
+    UnmarkRemainingPurpleVisitor visitor;
+    aBlock->VisitEntries(*this, visitor);
+  }
+
+  void SelectPointers(CCGraphBuilder& aBuilder);
+
+  // RemoveSkippable removes entries from the purple buffer synchronously
+  // (1) if aAsyncSnowWhiteFreeing is false and nsPurpleBufferEntry::mRefCnt is 0 or
+  // (2) if the object's nsXPCOMCycleCollectionParticipant::CanSkip() returns true or
+  // (3) if nsPurpleBufferEntry::mRefCnt->IsPurple() is false.
+  // (4) If removeChildlessNodes is true, then any nodes in the purple buffer
+  //     that will have no children in the cycle collector graph will also be
+  //     removed. CanSkip() may be run on these children.
+  void RemoveSkippable(nsCycleCollector* aCollector,
+                       bool aRemoveChildlessNodes,
+                       bool aAsyncSnowWhiteFreeing,
+                       CC_ForgetSkippableCallback aCb);
+
+  MOZ_ALWAYS_INLINE nsPurpleBufferEntry* NewEntry()
+  {
+    if (MOZ_UNLIKELY(!mFreeList)) {
+      PurpleBlock* b = new PurpleBlock;
+      mFreeList = b->mEntries;
+
+      // Add the new block as the second block in the list.
+      b->mNext = mFirstBlock.mNext;
+      mFirstBlock.mNext = b;
+    }
+
+    nsPurpleBufferEntry* e = mFreeList;
+    mFreeList = (nsPurpleBufferEntry*)
+      (uintptr_t(mFreeList->mNextInFreeList) & ~uintptr_t(1));
+    return e;
+  }
+
+  MOZ_ALWAYS_INLINE void Put(void* aObject, nsCycleCollectionParticipant* aCp,
+                             nsCycleCollectingAutoRefCnt* aRefCnt)
+  {
+    nsPurpleBufferEntry* e = NewEntry();
+
+    ++mCount;
+
+    e->mObject = aObject;
+    e->mRefCnt = aRefCnt;
+    e->mParticipant = aCp;
+  }
+
+  void Remove(nsPurpleBufferEntry* aEntry)
+  {
+    MOZ_ASSERT(mCount != 0, "must have entries");
+
+    if (aEntry->mRefCnt) {
+      aEntry->mRefCnt->RemoveFromPurpleBuffer();
+      aEntry->mRefCnt = nullptr;
+    }
+    aEntry->mNextInFreeList =
+      (nsPurpleBufferEntry*)(uintptr_t(mFreeList) | uintptr_t(1));
+    mFreeList = aEntry;
+
+    --mCount;
+  }
+
+  uint32_t Count() const
+  {
+    return mCount;
+  }
+
+  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
+  {
+    size_t n = 0;
+
+    // Don't measure mFirstBlock because it's within |this|.
+    const PurpleBlock* block = mFirstBlock.mNext;
+    while (block) {
+      n += aMallocSizeOf(block);
+      block = block->mNext;
+    }
+
+    // mFreeList is deliberately not measured because it points into
+    // the purple buffer, which is within mFirstBlock and thus within |this|.
+    //
+    // We also don't measure the things pointed to by mEntries[] because
+    // those pointers are non-owning.
+
+    return n;
+  }
+};
+
+static bool
+AddPurpleRoot(CCGraphBuilder& aBuilder, void* aRoot,
+              nsCycleCollectionParticipant* aParti);
+
+struct SelectPointersVisitor
+{
+  explicit SelectPointersVisitor(CCGraphBuilder& aBuilder)
+    : mBuilder(aBuilder)
+  {
+  }
+
+  void
+  Visit(nsPurpleBuffer& aBuffer, nsPurpleBufferEntry* aEntry)
+  {
+    MOZ_ASSERT(aEntry->mObject, "Null object in purple buffer");
+    MOZ_ASSERT(aEntry->mRefCnt->get() != 0,
+               "SelectPointersVisitor: snow-white object in the purple buffer");
+    if (!aEntry->mRefCnt->IsPurple() ||
+        AddPurpleRoot(mBuilder, aEntry->mObject, aEntry->mParticipant)) {
+      aBuffer.Remove(aEntry);
+    }
+  }
+
+private:
+  CCGraphBuilder& mBuilder;
+};
+
+void
+nsPurpleBuffer::SelectPointers(CCGraphBuilder& aBuilder)
+{
+  SelectPointersVisitor visitor(aBuilder);
+  VisitEntries(visitor);
+
+  NS_ASSERTION(mCount == 0, "AddPurpleRoot failed");
+  if (mCount == 0) {
+    FreeBlocks();
+    InitBlocks();
+    mFirstBlock.InitNextPointers();
+  }
+}
+
+enum ccPhase
+{
+  IdlePhase,
+  GraphBuildingPhase,
+  ScanAndCollectWhitePhase,
+  CleanupPhase
+};
+
+enum ccType
+{
+  SliceCC,     /* If a CC is in progress, continue it. Otherwise, start a new one. */
+  ManualCC,    /* Explicitly triggered. */
+  ShutdownCC   /* Shutdown CC, used for finding leaks. */
+};
+
+////////////////////////////////////////////////////////////////////////
+// Top level structure for the cycle collector.
+////////////////////////////////////////////////////////////////////////
+
+using js::SliceBudget;
+
+class JSPurpleBuffer;
+
+class nsCycleCollector : public nsIMemoryReporter
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIMEMORYREPORTER
+
+private:
+  bool mActivelyCollecting;
+  bool mFreeingSnowWhite;
+  // mScanInProgress should be false when we're collecting white objects.
+  bool mScanInProgress;
+  CycleCollectorResults mResults;
+  TimeStamp mCollectionStart;
+
+  CycleCollectedJSContext* mJSContext;
+
+  ccPhase mIncrementalPhase;
+  CCGraph mGraph;
+  nsAutoPtr<CCGraphBuilder> mBuilder;
+  RefPtr<nsCycleCollectorLogger> mLogger;
+
+#ifdef DEBUG
+  void* mThread;
+#endif
+
+  nsCycleCollectorParams mParams;
+
+  uint32_t mWhiteNodeCount;
+
+  CC_BeforeUnlinkCallback mBeforeUnlinkCB;
+  CC_ForgetSkippableCallback mForgetSkippableCB;
+
+  nsPurpleBuffer mPurpleBuf;
+
+  uint32_t mUnmergedNeeded;
+  uint32_t mMergedInARow;
+
+  RefPtr<JSPurpleBuffer> mJSPurpleBuffer;
+
+private:
+  virtual ~nsCycleCollector();
+
+public:
+  nsCycleCollector();
+
+  void RegisterJSContext(CycleCollectedJSContext* aJSContext);
+  void ForgetJSContext();
+
+  void SetBeforeUnlinkCallback(CC_BeforeUnlinkCallback aBeforeUnlinkCB)
+  {
+    CheckThreadSafety();
+    mBeforeUnlinkCB = aBeforeUnlinkCB;
+  }
+
+  void SetForgetSkippableCallback(CC_ForgetSkippableCallback aForgetSkippableCB)
+  {
+    CheckThreadSafety();
+    mForgetSkippableCB = aForgetSkippableCB;
+  }
+
+  void Suspect(void* aPtr, nsCycleCollectionParticipant* aCp,
+               nsCycleCollectingAutoRefCnt* aRefCnt);
+  uint32_t SuspectedCount();
+  void ForgetSkippable(bool aRemoveChildlessNodes, bool aAsyncSnowWhiteFreeing);
+  bool FreeSnowWhite(bool aUntilNoSWInPurpleBuffer);
+
+  // This method assumes its argument is already canonicalized.
+  void RemoveObjectFromGraph(void* aPtr);
+
+  void PrepareForGarbageCollection();
+  void FinishAnyCurrentCollection();
+
+  bool Collect(ccType aCCType,
+               SliceBudget& aBudget,
+               nsICycleCollectorListener* aManualListener,
+               bool aPreferShorterSlices = false);
+  void Shutdown(bool aDoCollect);
+
+  bool IsIdle() const { return mIncrementalPhase == IdlePhase; }
+
+  void SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf,
+                           size_t* aObjectSize,
+                           size_t* aGraphSize,
+                           size_t* aPurpleBufferSize) const;
+
+  JSPurpleBuffer* GetJSPurpleBuffer();
+
+  CycleCollectedJSContext* Context() { return mJSContext; }
+
+private:
+  void CheckThreadSafety();
+  void ShutdownCollect();
+
+  void FixGrayBits(bool aForceGC, TimeLog& aTimeLog);
+  bool IsIncrementalGCInProgress();
+  void FinishAnyIncrementalGCInProgress();
+  bool ShouldMergeZones(ccType aCCType);
+
+  void BeginCollection(ccType aCCType, nsICycleCollectorListener* aManualListener);
+  void MarkRoots(SliceBudget& aBudget);
+  void ScanRoots(bool aFullySynchGraphBuild);
+  void ScanIncrementalRoots();
+  void ScanWhiteNodes(bool aFullySynchGraphBuild);
+  void ScanBlackNodes();
+  void ScanWeakMaps();
+
+  // returns whether anything was collected
+  bool CollectWhite();
+
+  void CleanupAfterCollection();
+};
+
+NS_IMPL_ISUPPORTS(nsCycleCollector, nsIMemoryReporter)
+
+/**
+ * GraphWalker is templatized over a Visitor class that must provide
+ * the following two methods:
+ *
+ * bool ShouldVisitNode(PtrInfo const *pi);
+ * void VisitNode(PtrInfo *pi);
+ */
+template<class Visitor>
+class GraphWalker
+{
+private:
+  Visitor mVisitor;
+
+  void DoWalk(nsDeque& aQueue);
+
+  void CheckedPush(nsDeque& aQueue, PtrInfo* aPi)
+  {
+    if (!aPi) {
+      MOZ_CRASH();
+    }
+    if (!aQueue.Push(aPi, fallible)) {
+      mVisitor.Failed();
+    }
+  }
+
+public:
+  void Walk(PtrInfo* aPi);
+  void WalkFromRoots(CCGraph& aGraph);
+  // copy-constructing the visitor should be cheap, and less
+  // indirection than using a reference
+  explicit GraphWalker(const Visitor aVisitor) : mVisitor(aVisitor)
+  {
+  }
+};
+
+
+////////////////////////////////////////////////////////////////////////
+// The static collector struct
+////////////////////////////////////////////////////////////////////////
+
+struct CollectorData
+{
+  RefPtr<nsCycleCollector> mCollector;
+  CycleCollectedJSContext* mContext;
+};
+
+static MOZ_THREAD_LOCAL(CollectorData*) sCollectorData;
+
+////////////////////////////////////////////////////////////////////////
+// Utility functions
+////////////////////////////////////////////////////////////////////////
+
+static inline void
+ToParticipant(nsISupports* aPtr, nsXPCOMCycleCollectionParticipant** aCp)
+{
+  // We use QI to move from an nsISupports to an
+  // nsXPCOMCycleCollectionParticipant, which is a per-class singleton helper
+  // object that implements traversal and unlinking logic for the nsISupports
+  // in question.
+  *aCp = nullptr;
+  CallQueryInterface(aPtr, aCp);
+}
+
+template<class Visitor>
+MOZ_NEVER_INLINE void
+GraphWalker<Visitor>::Walk(PtrInfo* aPi)
+{
+  nsDeque queue;
+  CheckedPush(queue, aPi);
+  DoWalk(queue);
+}
+
+template<class Visitor>
+MOZ_NEVER_INLINE void
+GraphWalker<Visitor>::WalkFromRoots(CCGraph& aGraph)
+{
+  nsDeque queue;
+  NodePool::Enumerator etor(aGraph.mNodes);
+  for (uint32_t i = 0; i < aGraph.mRootCount; ++i) {
+    CheckedPush(queue, etor.GetNext());
+  }
+  DoWalk(queue);
+}
+
+template<class Visitor>
+MOZ_NEVER_INLINE void
+GraphWalker<Visitor>::DoWalk(nsDeque& aQueue)
+{
+  // Use a aQueue to match the breadth-first traversal used when we
+  // built the graph, for hopefully-better locality.
+  while (aQueue.GetSize() > 0) {
+    PtrInfo* pi = static_cast<PtrInfo*>(aQueue.PopFront());
+
+    if (pi->WasTraversed() && mVisitor.ShouldVisitNode(pi)) {
+      mVisitor.VisitNode(pi);
+      for (EdgePool::Iterator child = pi->FirstChild(),
+           child_end = pi->LastChild();
+           child != child_end; ++child) {
+        CheckedPush(aQueue, *child);
+      }
+    }
+  }
+}
+
+struct CCGraphDescriber : public LinkedListElement<CCGraphDescriber>
+{
+  CCGraphDescriber()
+    : mAddress("0x"), mCnt(0), mType(eUnknown)
+  {
+  }
+
+  enum Type
+  {
+    eRefCountedObject,
+    eGCedObject,
+    eGCMarkedObject,
+    eEdge,
+    eRoot,
+    eGarbage,
+    eUnknown
+  };
+
+  nsCString mAddress;
+  nsCString mName;
+  nsCString mCompartmentOrToAddress;
+  uint32_t mCnt;
+  Type mType;
+};
+
+class LogStringMessageAsync : public CancelableRunnable
+{
+public:
+  explicit LogStringMessageAsync(const nsAString& aMsg) : mMsg(aMsg)
+  {}
+
+  NS_IMETHOD Run() override
+  {
+    nsCOMPtr<nsIConsoleService> cs =
+      do_GetService(NS_CONSOLESERVICE_CONTRACTID);
+    if (cs) {
+       cs->LogStringMessage(mMsg.get());
+    }
+    return NS_OK;
+  }
+
+private:
+  nsString mMsg;
+};
+
+class nsCycleCollectorLogSinkToFile final : public nsICycleCollectorLogSink
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  nsCycleCollectorLogSinkToFile() :
+    mProcessIdentifier(base::GetCurrentProcId()),
+    mGCLog("gc-edges"), mCCLog("cc-edges")
+  {
+  }
+
+  NS_IMETHOD GetFilenameIdentifier(nsAString& aIdentifier) override
+  {
+    aIdentifier = mFilenameIdentifier;
+    return NS_OK;
+  }
+
+  NS_IMETHOD SetFilenameIdentifier(const nsAString& aIdentifier) override
+  {
+    mFilenameIdentifier = aIdentifier;
+    return NS_OK;
+  }
+
+  NS_IMETHOD GetProcessIdentifier(int32_t* aIdentifier) override
+  {
+    *aIdentifier = mProcessIdentifier;
+    return NS_OK;
+  }
+
+  NS_IMETHOD SetProcessIdentifier(int32_t aIdentifier) override
+  {
+    mProcessIdentifier = aIdentifier;
+    return NS_OK;
+  }
+
+  NS_IMETHOD GetGcLog(nsIFile** aPath) override
+  {
+    NS_IF_ADDREF(*aPath = mGCLog.mFile);
+    return NS_OK;
+  }
+
+  NS_IMETHOD GetCcLog(nsIFile** aPath) override
+  {
+    NS_IF_ADDREF(*aPath = mCCLog.mFile);
+    return NS_OK;
+  }
+
+  NS_IMETHOD Open(FILE** aGCLog, FILE** aCCLog) override
+  {
+    nsresult rv;
+
+    if (mGCLog.mStream || mCCLog.mStream) {
+      return NS_ERROR_UNEXPECTED;
+    }
+
+    rv = OpenLog(&mGCLog);
+    NS_ENSURE_SUCCESS(rv, rv);
+    *aGCLog = mGCLog.mStream;
+
+    rv = OpenLog(&mCCLog);
+    NS_ENSURE_SUCCESS(rv, rv);
+    *aCCLog = mCCLog.mStream;
+
+    return NS_OK;
+  }
+
+  NS_IMETHOD CloseGCLog() override
+  {
+    if (!mGCLog.mStream) {
+      return NS_ERROR_UNEXPECTED;
+    }
+    CloseLog(&mGCLog, NS_LITERAL_STRING("Garbage"));
+    return NS_OK;
+  }
+
+  NS_IMETHOD CloseCCLog() override
+  {
+    if (!mCCLog.mStream) {
+      return NS_ERROR_UNEXPECTED;
+    }
+    CloseLog(&mCCLog, NS_LITERAL_STRING("Cycle"));
+    return NS_OK;
+  }
+
+private:
+  ~nsCycleCollectorLogSinkToFile()
+  {
+    if (mGCLog.mStream) {
+      MozillaUnRegisterDebugFILE(mGCLog.mStream);
+      fclose(mGCLog.mStream);
+    }
+    if (mCCLog.mStream) {
+      MozillaUnRegisterDebugFILE(mCCLog.mStream);
+      fclose(mCCLog.mStream);
+    }
+  }
+
+  struct FileInfo
+  {
+    const char* const mPrefix;
+    nsCOMPtr<nsIFile> mFile;
+    FILE* mStream;
+
+    explicit FileInfo(const char* aPrefix) : mPrefix(aPrefix), mStream(nullptr) { }
+  };
+
+  /**
+   * Create a new file named something like aPrefix.$PID.$IDENTIFIER.log in
+   * $MOZ_CC_LOG_DIRECTORY or in the system's temp directory.  No existing
+   * file will be overwritten; if aPrefix.$PID.$IDENTIFIER.log exists, we'll
+   * try a file named something like aPrefix.$PID.$IDENTIFIER-1.log, and so
+   * on.
+   */
+  already_AddRefed<nsIFile> CreateTempFile(const char* aPrefix)
+  {
+    nsPrintfCString filename("%s.%d%s%s.log",
+                             aPrefix,
+                             mProcessIdentifier,
+                             mFilenameIdentifier.IsEmpty() ? "" : ".",
+                             NS_ConvertUTF16toUTF8(mFilenameIdentifier).get());
+
+    // Get the log directory either from $MOZ_CC_LOG_DIRECTORY or from
+    // the fallback directories in OpenTempFile.  We don't use an nsCOMPtr
+    // here because OpenTempFile uses an in/out param and getter_AddRefs
+    // wouldn't work.
+    nsIFile* logFile = nullptr;
+    if (char* env = PR_GetEnv("MOZ_CC_LOG_DIRECTORY")) {
+      NS_NewNativeLocalFile(nsCString(env), /* followLinks = */ true,
+                            &logFile);
+    }
+
+    // On Android or B2G, this function will open a file named
+    // aFilename under a memory-reporting-specific folder
+    // (/data/local/tmp/memory-reports). Otherwise, it will open a
+    // file named aFilename under "NS_OS_TEMP_DIR".
+    nsresult rv = nsDumpUtils::OpenTempFile(filename, &logFile,
+                                            NS_LITERAL_CSTRING("memory-reports"));
+    if (NS_FAILED(rv)) {
+      NS_IF_RELEASE(logFile);
+      return nullptr;
+    }
+
+    return dont_AddRef(logFile);
+  }
+
+  nsresult OpenLog(FileInfo* aLog)
+  {
+    // Initially create the log in a file starting with "incomplete-".
+    // We'll move the file and strip off the "incomplete-" once the dump
+    // completes.  (We do this because we don't want scripts which poll
+    // the filesystem looking for GC/CC dumps to grab a file before we're
+    // finished writing to it.)
+    nsAutoCString incomplete;
+    incomplete += "incomplete-";
+    incomplete += aLog->mPrefix;
+    MOZ_ASSERT(!aLog->mFile);
+    aLog->mFile = CreateTempFile(incomplete.get());
+    if (NS_WARN_IF(!aLog->mFile)) {
+      return NS_ERROR_UNEXPECTED;
+    }
+
+    MOZ_ASSERT(!aLog->mStream);
+    nsresult rv = aLog->mFile->OpenANSIFileDesc("w", &aLog->mStream);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return NS_ERROR_UNEXPECTED;
+    }
+    MozillaRegisterDebugFILE(aLog->mStream);
+    return NS_OK;
+  }
+
+  nsresult CloseLog(FileInfo* aLog, const nsAString& aCollectorKind)
+  {
+    MOZ_ASSERT(aLog->mStream);
+    MOZ_ASSERT(aLog->mFile);
+
+    MozillaUnRegisterDebugFILE(aLog->mStream);
+    fclose(aLog->mStream);
+    aLog->mStream = nullptr;
+
+    // Strip off "incomplete-".
+    nsCOMPtr<nsIFile> logFileFinalDestination =
+      CreateTempFile(aLog->mPrefix);
+    if (NS_WARN_IF(!logFileFinalDestination)) {
+      return NS_ERROR_UNEXPECTED;
+    }
+
+    nsAutoString logFileFinalDestinationName;
+    logFileFinalDestination->GetLeafName(logFileFinalDestinationName);
+    if (NS_WARN_IF(logFileFinalDestinationName.IsEmpty())) {
+      return NS_ERROR_UNEXPECTED;
+    }
+
+    aLog->mFile->MoveTo(/* directory */ nullptr, logFileFinalDestinationName);
+
+    // Save the file path.
+    aLog->mFile = logFileFinalDestination;
+
+    // Log to the error console.
+    nsAutoString logPath;
+    logFileFinalDestination->GetPath(logPath);
+    nsAutoString msg = aCollectorKind +
+      NS_LITERAL_STRING(" Collector log dumped to ") + logPath;
+
+    // We don't want any JS to run between ScanRoots and CollectWhite calls,
+    // and since ScanRoots calls this method, better to log the message
+    // asynchronously.
+    RefPtr<LogStringMessageAsync> log = new LogStringMessageAsync(msg);
+    NS_DispatchToCurrentThread(log);
+    return NS_OK;
+  }
+
+  int32_t mProcessIdentifier;
+  nsString mFilenameIdentifier;
+  FileInfo mGCLog;
+  FileInfo mCCLog;
+};
+
+NS_IMPL_ISUPPORTS(nsCycleCollectorLogSinkToFile, nsICycleCollectorLogSink)
+
+
+class nsCycleCollectorLogger final : public nsICycleCollectorListener
+{
+  ~nsCycleCollectorLogger()
+  {
+    ClearDescribers();
+  }
+
+public:
+  nsCycleCollectorLogger()
+    : mLogSink(nsCycleCollector_createLogSink())
+    , mWantAllTraces(false)
+    , mDisableLog(false)
+    , mWantAfterProcessing(false)
+    , mCCLog(nullptr)
+  {
+  }
+
+  NS_DECL_ISUPPORTS
+
+  void SetAllTraces()
+  {
+    mWantAllTraces = true;
+  }
+
+  bool IsAllTraces()
+  {
+    return mWantAllTraces;
+  }
+
+  NS_IMETHOD AllTraces(nsICycleCollectorListener** aListener) override
+  {
+    SetAllTraces();
+    NS_ADDREF(*aListener = this);
+    return NS_OK;
+  }
+
+  NS_IMETHOD GetWantAllTraces(bool* aAllTraces) override
+  {
+    *aAllTraces = mWantAllTraces;
+    return NS_OK;
+  }
+
+  NS_IMETHOD GetDisableLog(bool* aDisableLog) override
+  {
+    *aDisableLog = mDisableLog;
+    return NS_OK;
+  }
+
+  NS_IMETHOD SetDisableLog(bool aDisableLog) override
+  {
+    mDisableLog = aDisableLog;
+    return NS_OK;
+  }
+
+  NS_IMETHOD GetWantAfterProcessing(bool* aWantAfterProcessing) override
+  {
+    *aWantAfterProcessing = mWantAfterProcessing;
+    return NS_OK;
+  }
+
+  NS_IMETHOD SetWantAfterProcessing(bool aWantAfterProcessing) override
+  {
+    mWantAfterProcessing = aWantAfterProcessing;
+    return NS_OK;
+  }
+
+  NS_IMETHOD GetLogSink(nsICycleCollectorLogSink** aLogSink) override
+  {
+    NS_ADDREF(*aLogSink = mLogSink);
+    return NS_OK;
+  }
+
+  NS_IMETHOD SetLogSink(nsICycleCollectorLogSink* aLogSink) override
+  {
+    if (!aLogSink) {
+      return NS_ERROR_INVALID_ARG;
+    }
+    mLogSink = aLogSink;
+    return NS_OK;
+  }
+
+  nsresult Begin()
+  {
+    nsresult rv;
+
+    mCurrentAddress.AssignLiteral("0x");
+    ClearDescribers();
+    if (mDisableLog) {
+      return NS_OK;
+    }
+
+    FILE* gcLog;
+    rv = mLogSink->Open(&gcLog, &mCCLog);
+    NS_ENSURE_SUCCESS(rv, rv);
+    // Dump the JS heap.
+    CollectorData* data = sCollectorData.get();
+    if (data && data->mContext) {
+      data->mContext->DumpJSHeap(gcLog);
+    }
+    rv = mLogSink->CloseGCLog();
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    fprintf(mCCLog, "# WantAllTraces=%s\n", mWantAllTraces ? "true" : "false");
+    return NS_OK;
+  }
+  void NoteRefCountedObject(uint64_t aAddress, uint32_t aRefCount,
+                            const char* aObjectDescription)
+  {
+    if (!mDisableLog) {
+      fprintf(mCCLog, "%p [rc=%u] %s\n", (void*)aAddress, aRefCount,
+              aObjectDescription);
+    }
+    if (mWantAfterProcessing) {
+      CCGraphDescriber* d =  new CCGraphDescriber();
+      mDescribers.insertBack(d);
+      mCurrentAddress.AssignLiteral("0x");
+      mCurrentAddress.AppendInt(aAddress, 16);
+      d->mType = CCGraphDescriber::eRefCountedObject;
+      d->mAddress = mCurrentAddress;
+      d->mCnt = aRefCount;
+      d->mName.Append(aObjectDescription);
+    }
+  }
+  void NoteGCedObject(uint64_t aAddress, bool aMarked,
+                      const char* aObjectDescription,
+                      uint64_t aCompartmentAddress)
+  {
+    if (!mDisableLog) {
+      fprintf(mCCLog, "%p [gc%s] %s\n", (void*)aAddress,
+              aMarked ? ".marked" : "", aObjectDescription);
+    }
+    if (mWantAfterProcessing) {
+      CCGraphDescriber* d =  new CCGraphDescriber();
+      mDescribers.insertBack(d);
+      mCurrentAddress.AssignLiteral("0x");
+      mCurrentAddress.AppendInt(aAddress, 16);
+      d->mType = aMarked ? CCGraphDescriber::eGCMarkedObject :
+                           CCGraphDescriber::eGCedObject;
+      d->mAddress = mCurrentAddress;
+      d->mName.Append(aObjectDescription);
+      if (aCompartmentAddress) {
+        d->mCompartmentOrToAddress.AssignLiteral("0x");
+        d->mCompartmentOrToAddress.AppendInt(aCompartmentAddress, 16);
+      } else {
+        d->mCompartmentOrToAddress.SetIsVoid(true);
+      }
+    }
+  }
+  void NoteEdge(uint64_t aToAddress, const char* aEdgeName)
+  {
+    if (!mDisableLog) {
+      fprintf(mCCLog, "> %p %s\n", (void*)aToAddress, aEdgeName);
+    }
+    if (mWantAfterProcessing) {
+      CCGraphDescriber* d =  new CCGraphDescriber();
+      mDescribers.insertBack(d);
+      d->mType = CCGraphDescriber::eEdge;
+      d->mAddress = mCurrentAddress;
+      d->mCompartmentOrToAddress.AssignLiteral("0x");
+      d->mCompartmentOrToAddress.AppendInt(aToAddress, 16);
+      d->mName.Append(aEdgeName);
+    }
+  }
+  void NoteWeakMapEntry(uint64_t aMap, uint64_t aKey,
+                        uint64_t aKeyDelegate, uint64_t aValue)
+  {
+    if (!mDisableLog) {
+      fprintf(mCCLog, "WeakMapEntry map=%p key=%p keyDelegate=%p value=%p\n",
+              (void*)aMap, (void*)aKey, (void*)aKeyDelegate, (void*)aValue);
+    }
+    // We don't support after-processing for weak map entries.
+  }
+  void NoteIncrementalRoot(uint64_t aAddress)
+  {
+    if (!mDisableLog) {
+      fprintf(mCCLog, "IncrementalRoot %p\n", (void*)aAddress);
+    }
+    // We don't support after-processing for incremental roots.
+  }
+  void BeginResults()
+  {
+    if (!mDisableLog) {
+      fputs("==========\n", mCCLog);
+    }
+  }
+  void DescribeRoot(uint64_t aAddress, uint32_t aKnownEdges)
+  {
+    if (!mDisableLog) {
+      fprintf(mCCLog, "%p [known=%u]\n", (void*)aAddress, aKnownEdges);
+    }
+    if (mWantAfterProcessing) {
+      CCGraphDescriber* d =  new CCGraphDescriber();
+      mDescribers.insertBack(d);
+      d->mType = CCGraphDescriber::eRoot;
+      d->mAddress.AppendInt(aAddress, 16);
+      d->mCnt = aKnownEdges;
+    }
+  }
+  void DescribeGarbage(uint64_t aAddress)
+  {
+    if (!mDisableLog) {
+      fprintf(mCCLog, "%p [garbage]\n", (void*)aAddress);
+    }
+    if (mWantAfterProcessing) {
+      CCGraphDescriber* d =  new CCGraphDescriber();
+      mDescribers.insertBack(d);
+      d->mType = CCGraphDescriber::eGarbage;
+      d->mAddress.AppendInt(aAddress, 16);
+    }
+  }
+  void End()
+  {
+    if (!mDisableLog) {
+      mCCLog = nullptr;
+      Unused << NS_WARN_IF(NS_FAILED(mLogSink->CloseCCLog()));
+    }
+  }
+  NS_IMETHOD ProcessNext(nsICycleCollectorHandler* aHandler,
+                         bool* aCanContinue) override
+  {
+    if (NS_WARN_IF(!aHandler) || NS_WARN_IF(!mWantAfterProcessing)) {
+      return NS_ERROR_UNEXPECTED;
+    }
+    CCGraphDescriber* d = mDescribers.popFirst();
+    if (d) {
+      switch (d->mType) {
+        case CCGraphDescriber::eRefCountedObject:
+          aHandler->NoteRefCountedObject(d->mAddress,
+                                         d->mCnt,
+                                         d->mName);
+          break;
+        case CCGraphDescriber::eGCedObject:
+        case CCGraphDescriber::eGCMarkedObject:
+          aHandler->NoteGCedObject(d->mAddress,
+                                   d->mType ==
+                                     CCGraphDescriber::eGCMarkedObject,
+                                   d->mName,
+                                   d->mCompartmentOrToAddress);
+          break;
+        case CCGraphDescriber::eEdge:
+          aHandler->NoteEdge(d->mAddress,
+                             d->mCompartmentOrToAddress,
+                             d->mName);
+          break;
+        case CCGraphDescriber::eRoot:
+          aHandler->DescribeRoot(d->mAddress,
+                                 d->mCnt);
+          break;
+        case CCGraphDescriber::eGarbage:
+          aHandler->DescribeGarbage(d->mAddress);
+          break;
+        case CCGraphDescriber::eUnknown:
+          NS_NOTREACHED("CCGraphDescriber::eUnknown");
+          break;
+      }
+      delete d;
+    }
+    if (!(*aCanContinue = !mDescribers.isEmpty())) {
+      mCurrentAddress.AssignLiteral("0x");
+    }
+    return NS_OK;
+  }
+  NS_IMETHOD AsLogger(nsCycleCollectorLogger** aRetVal) override
+  {
+    RefPtr<nsCycleCollectorLogger> rval = this;
+    rval.forget(aRetVal);
+    return NS_OK;
+  }
+private:
+  void ClearDescribers()
+  {
+    CCGraphDescriber* d;
+    while ((d = mDescribers.popFirst())) {
+      delete d;
+    }
+  }
+
+  nsCOMPtr<nsICycleCollectorLogSink> mLogSink;
+  bool mWantAllTraces;
+  bool mDisableLog;
+  bool mWantAfterProcessing;
+  nsCString mCurrentAddress;
+  mozilla::LinkedList<CCGraphDescriber> mDescribers;
+  FILE* mCCLog;
+};
+
+NS_IMPL_ISUPPORTS(nsCycleCollectorLogger, nsICycleCollectorListener)
+
+nsresult
+nsCycleCollectorLoggerConstructor(nsISupports* aOuter,
+                                  const nsIID& aIID,
+                                  void** aInstancePtr)
+{
+  if (NS_WARN_IF(aOuter)) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+
+  nsISupports* logger = new nsCycleCollectorLogger();
+
+  return logger->QueryInterface(aIID, aInstancePtr);
+}
+
+static bool
+GCThingIsGrayCCThing(JS::GCCellPtr thing)
+{
+    return AddToCCKind(thing.kind()) &&
+           JS::GCThingIsMarkedGray(thing);
+}
+
+static bool
+ValueIsGrayCCThing(const JS::Value& value)
+{
+    return AddToCCKind(value.traceKind()) &&
+           JS::GCThingIsMarkedGray(value.toGCCellPtr());
+}
+
+////////////////////////////////////////////////////////////////////////
+// Bacon & Rajan's |MarkRoots| routine.
+////////////////////////////////////////////////////////////////////////
+
+class CCGraphBuilder final : public nsCycleCollectionTraversalCallback,
+  public nsCycleCollectionNoteRootCallback
+{
+private:
+  CCGraph& mGraph;
+  CycleCollectorResults& mResults;
+  NodePool::Builder mNodeBuilder;
+  EdgePool::Builder mEdgeBuilder;
+  MOZ_INIT_OUTSIDE_CTOR PtrInfo* mCurrPi;
+  nsCycleCollectionParticipant* mJSParticipant;
+  nsCycleCollectionParticipant* mJSZoneParticipant;
+  nsCString mNextEdgeName;
+  RefPtr<nsCycleCollectorLogger> mLogger;
+  bool mMergeZones;
+  nsAutoPtr<NodePool::Enumerator> mCurrNode;
+
+public:
+  CCGraphBuilder(CCGraph& aGraph,
+                 CycleCollectorResults& aResults,
+                 CycleCollectedJSContext* aJSContext,
+                 nsCycleCollectorLogger* aLogger,
+                 bool aMergeZones);
+  virtual ~CCGraphBuilder();
+
+  bool WantAllTraces() const
+  {
+    return nsCycleCollectionNoteRootCallback::WantAllTraces();
+  }
+
+  bool AddPurpleRoot(void* aRoot, nsCycleCollectionParticipant* aParti);
+
+  // This is called when all roots have been added to the graph, to prepare for BuildGraph().
+  void DoneAddingRoots();
+
+  // Do some work traversing nodes in the graph. Returns true if this graph building is finished.
+  bool BuildGraph(SliceBudget& aBudget);
+
+private:
+  PtrInfo* AddNode(void* aPtr, nsCycleCollectionParticipant* aParticipant);
+  PtrInfo* AddWeakMapNode(JS::GCCellPtr aThing);
+  PtrInfo* AddWeakMapNode(JSObject* aObject);
+
+  void SetFirstChild()
+  {
+    mCurrPi->SetFirstChild(mEdgeBuilder.Mark());
+  }
+
+  void SetLastChild()
+  {
+    mCurrPi->SetLastChild(mEdgeBuilder.Mark());
+  }
+
+public:
+  // nsCycleCollectionNoteRootCallback methods.
+  NS_IMETHOD_(void) NoteXPCOMRoot(nsISupports* aRoot);
+  NS_IMETHOD_(void) NoteJSRoot(JSObject* aRoot);
+  NS_IMETHOD_(void) NoteNativeRoot(void* aRoot,
+                                   nsCycleCollectionParticipant* aParticipant);
+  NS_IMETHOD_(void) NoteWeakMapping(JSObject* aMap, JS::GCCellPtr aKey,
+                                    JSObject* aKdelegate, JS::GCCellPtr aVal);
+
+  // nsCycleCollectionTraversalCallback methods.
+  NS_IMETHOD_(void) DescribeRefCountedNode(nsrefcnt aRefCount,
+                                           const char* aObjName);
+  NS_IMETHOD_(void) DescribeGCedNode(bool aIsMarked, const char* aObjName,
+                                     uint64_t aCompartmentAddress);
+
+  NS_IMETHOD_(void) NoteXPCOMChild(nsISupports* aChild);
+  NS_IMETHOD_(void) NoteJSChild(const JS::GCCellPtr& aThing);
+  NS_IMETHOD_(void) NoteNativeChild(void* aChild,
+                                    nsCycleCollectionParticipant* aParticipant);
+  NS_IMETHOD_(void) NoteNextEdgeName(const char* aName);
+
+private:
+  void NoteJSChild(JS::GCCellPtr aChild);
+
+  NS_IMETHOD_(void) NoteRoot(void* aRoot,
+                             nsCycleCollectionParticipant* aParticipant)
+  {
+    MOZ_ASSERT(aRoot);
+    MOZ_ASSERT(aParticipant);
+
+    if (!aParticipant->CanSkipInCC(aRoot) || MOZ_UNLIKELY(WantAllTraces())) {
+      AddNode(aRoot, aParticipant);
+    }
+  }
+
+  NS_IMETHOD_(void) NoteChild(void* aChild, nsCycleCollectionParticipant* aCp,
+                              nsCString& aEdgeName)
+  {
+    PtrInfo* childPi = AddNode(aChild, aCp);
+    if (!childPi) {
+      return;
+    }
+    mEdgeBuilder.Add(childPi);
+    if (mLogger) {
+      mLogger->NoteEdge((uint64_t)aChild, aEdgeName.get());
+    }
+    ++childPi->mInternalRefs;
+  }
+
+  JS::Zone* MergeZone(JS::GCCellPtr aGcthing)
+  {
+    if (!mMergeZones) {
+      return nullptr;
+    }
+    JS::Zone* zone = JS::GetTenuredGCThingZone(aGcthing);
+    if (js::IsSystemZone(zone)) {
+      return nullptr;
+    }
+    return zone;
+  }
+};
+
+CCGraphBuilder::CCGraphBuilder(CCGraph& aGraph,
+                               CycleCollectorResults& aResults,
+                               CycleCollectedJSContext* aJSContext,
+                               nsCycleCollectorLogger* aLogger,
+                               bool aMergeZones)
+  : mGraph(aGraph)
+  , mResults(aResults)
+  , mNodeBuilder(aGraph.mNodes)
+  , mEdgeBuilder(aGraph.mEdges)
+  , mJSParticipant(nullptr)
+  , mJSZoneParticipant(nullptr)
+  , mLogger(aLogger)
+  , mMergeZones(aMergeZones)
+{
+  if (aJSContext) {
+    mJSParticipant = aJSContext->GCThingParticipant();
+    mJSZoneParticipant = aJSContext->ZoneParticipant();
+  }
+
+  if (mLogger) {
+    mFlags |= nsCycleCollectionTraversalCallback::WANT_DEBUG_INFO;
+    if (mLogger->IsAllTraces()) {
+      mFlags |= nsCycleCollectionTraversalCallback::WANT_ALL_TRACES;
+      mWantAllTraces = true; // for nsCycleCollectionNoteRootCallback
+    }
+  }
+
+  mMergeZones = mMergeZones && MOZ_LIKELY(!WantAllTraces());
+
+  MOZ_ASSERT(nsCycleCollectionNoteRootCallback::WantAllTraces() ==
+             nsCycleCollectionTraversalCallback::WantAllTraces());
+}
+
+CCGraphBuilder::~CCGraphBuilder()
+{
+}
+
+PtrInfo*
+CCGraphBuilder::AddNode(void* aPtr, nsCycleCollectionParticipant* aParticipant)
+{
+  PtrToNodeEntry* e = mGraph.AddNodeToMap(aPtr);
+  if (!e) {
+    return nullptr;
+  }
+
+  PtrInfo* result;
+  if (!e->mNode) {
+    // New entry.
+    result = mNodeBuilder.Add(aPtr, aParticipant);
+    if (!result) {
+      return nullptr;
+    }
+
+    e->mNode = result;
+    NS_ASSERTION(result, "mNodeBuilder.Add returned null");
+  } else {
+    result = e->mNode;
+    MOZ_ASSERT(result->mParticipant == aParticipant,
+               "nsCycleCollectionParticipant shouldn't change!");
+  }
+  return result;
+}
+
+bool
+CCGraphBuilder::AddPurpleRoot(void* aRoot, nsCycleCollectionParticipant* aParti)
+{
+  CanonicalizeParticipant(&aRoot, &aParti);
+
+  if (WantAllTraces() || !aParti->CanSkipInCC(aRoot)) {
+    PtrInfo* pinfo = AddNode(aRoot, aParti);
+    if (!pinfo) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+void
+CCGraphBuilder::DoneAddingRoots()
+{
+  // We've finished adding roots, and everything in the graph is a root.
+  mGraph.mRootCount = mGraph.MapCount();
+
+  mCurrNode = new NodePool::Enumerator(mGraph.mNodes);
+}
+
+MOZ_NEVER_INLINE bool
+CCGraphBuilder::BuildGraph(SliceBudget& aBudget)
+{
+  const intptr_t kNumNodesBetweenTimeChecks = 1000;
+  const intptr_t kStep = SliceBudget::CounterReset / kNumNodesBetweenTimeChecks;
+
+  MOZ_ASSERT(mCurrNode);
+
+  while (!aBudget.isOverBudget() && !mCurrNode->IsDone()) {
+    PtrInfo* pi = mCurrNode->GetNext();
+    if (!pi) {
+      MOZ_CRASH();
+    }
+
+    mCurrPi = pi;
+
+    // We need to call SetFirstChild() even on deleted nodes, to set their
+    // firstChild() that may be read by a prior non-deleted neighbor.
+    SetFirstChild();
+
+    if (pi->mParticipant) {
+      nsresult rv = pi->mParticipant->Traverse(pi->mPointer, *this);
+      MOZ_RELEASE_ASSERT(!NS_FAILED(rv), "Cycle collector Traverse method failed");
+    }
+
+    if (mCurrNode->AtBlockEnd()) {
+      SetLastChild();
+    }
+
+    aBudget.step(kStep);
+  }
+
+  if (!mCurrNode->IsDone()) {
+    return false;
+  }
+
+  if (mGraph.mRootCount > 0) {
+    SetLastChild();
+  }
+
+  mCurrNode = nullptr;
+
+  return true;
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::NoteXPCOMRoot(nsISupports* aRoot)
+{
+  aRoot = CanonicalizeXPCOMParticipant(aRoot);
+  NS_ASSERTION(aRoot,
+               "Don't add objects that don't participate in collection!");
+
+  nsXPCOMCycleCollectionParticipant* cp;
+  ToParticipant(aRoot, &cp);
+
+  NoteRoot(aRoot, cp);
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::NoteJSRoot(JSObject* aRoot)
+{
+  if (JS::Zone* zone = MergeZone(JS::GCCellPtr(aRoot))) {
+    NoteRoot(zone, mJSZoneParticipant);
+  } else {
+    NoteRoot(aRoot, mJSParticipant);
+  }
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::NoteNativeRoot(void* aRoot,
+                               nsCycleCollectionParticipant* aParticipant)
+{
+  NoteRoot(aRoot, aParticipant);
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::DescribeRefCountedNode(nsrefcnt aRefCount, const char* aObjName)
+{
+  MOZ_RELEASE_ASSERT(aRefCount != 0, "CCed refcounted object has zero refcount");
+  MOZ_RELEASE_ASSERT(aRefCount != UINT32_MAX, "CCed refcounted object has overflowing refcount");
+
+  mResults.mVisitedRefCounted++;
+
+  if (mLogger) {
+    mLogger->NoteRefCountedObject((uint64_t)mCurrPi->mPointer, aRefCount,
+                                  aObjName);
+  }
+
+  mCurrPi->mRefCount = aRefCount;
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::DescribeGCedNode(bool aIsMarked, const char* aObjName,
+                                 uint64_t aCompartmentAddress)
+{
+  uint32_t refCount = aIsMarked ? UINT32_MAX : 0;
+  mResults.mVisitedGCed++;
+
+  if (mLogger) {
+    mLogger->NoteGCedObject((uint64_t)mCurrPi->mPointer, aIsMarked,
+                            aObjName, aCompartmentAddress);
+  }
+
+  mCurrPi->mRefCount = refCount;
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::NoteXPCOMChild(nsISupports* aChild)
+{
+  nsCString edgeName;
+  if (WantDebugInfo()) {
+    edgeName.Assign(mNextEdgeName);
+    mNextEdgeName.Truncate();
+  }
+  if (!aChild || !(aChild = CanonicalizeXPCOMParticipant(aChild))) {
+    return;
+  }
+
+  nsXPCOMCycleCollectionParticipant* cp;
+  ToParticipant(aChild, &cp);
+  if (cp && (!cp->CanSkipThis(aChild) || WantAllTraces())) {
+    NoteChild(aChild, cp, edgeName);
+  }
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::NoteNativeChild(void* aChild,
+                                nsCycleCollectionParticipant* aParticipant)
+{
+  nsCString edgeName;
+  if (WantDebugInfo()) {
+    edgeName.Assign(mNextEdgeName);
+    mNextEdgeName.Truncate();
+  }
+  if (!aChild) {
+    return;
+  }
+
+  MOZ_ASSERT(aParticipant, "Need a nsCycleCollectionParticipant!");
+  if (!aParticipant->CanSkipThis(aChild) || WantAllTraces()) {
+    NoteChild(aChild, aParticipant, edgeName);
+  }
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::NoteJSChild(const JS::GCCellPtr& aChild)
+{
+  if (!aChild) {
+    return;
+  }
+
+  nsCString edgeName;
+  if (MOZ_UNLIKELY(WantDebugInfo())) {
+    edgeName.Assign(mNextEdgeName);
+    mNextEdgeName.Truncate();
+  }
+
+  if (GCThingIsGrayCCThing(aChild) || MOZ_UNLIKELY(WantAllTraces())) {
+    if (JS::Zone* zone = MergeZone(aChild)) {
+      NoteChild(zone, mJSZoneParticipant, edgeName);
+    } else {
+      NoteChild(aChild.asCell(), mJSParticipant, edgeName);
+    }
+  }
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::NoteNextEdgeName(const char* aName)
+{
+  if (WantDebugInfo()) {
+    mNextEdgeName = aName;
+  }
+}
+
+PtrInfo*
+CCGraphBuilder::AddWeakMapNode(JS::GCCellPtr aNode)
+{
+  MOZ_ASSERT(aNode, "Weak map node should be non-null.");
+
+  if (!GCThingIsGrayCCThing(aNode) && !WantAllTraces()) {
+    return nullptr;
+  }
+
+  if (JS::Zone* zone = MergeZone(aNode)) {
+    return AddNode(zone, mJSZoneParticipant);
+  }
+  return AddNode(aNode.asCell(), mJSParticipant);
+}
+
+PtrInfo*
+CCGraphBuilder::AddWeakMapNode(JSObject* aObject)
+{
+  return AddWeakMapNode(JS::GCCellPtr(aObject));
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::NoteWeakMapping(JSObject* aMap, JS::GCCellPtr aKey,
+                                JSObject* aKdelegate, JS::GCCellPtr aVal)
+{
+  // Don't try to optimize away the entry here, as we've already attempted to
+  // do that in TraceWeakMapping in nsXPConnect.
+  WeakMapping* mapping = mGraph.mWeakMaps.AppendElement();
+  mapping->mMap = aMap ? AddWeakMapNode(aMap) : nullptr;
+  mapping->mKey = aKey ? AddWeakMapNode(aKey) : nullptr;
+  mapping->mKeyDelegate = aKdelegate ? AddWeakMapNode(aKdelegate) : mapping->mKey;
+  mapping->mVal = aVal ? AddWeakMapNode(aVal) : nullptr;
+
+  if (mLogger) {
+    mLogger->NoteWeakMapEntry((uint64_t)aMap, aKey ? aKey.unsafeAsInteger() : 0,
+                              (uint64_t)aKdelegate,
+                              aVal ? aVal.unsafeAsInteger() : 0);
+  }
+}
+
+static bool
+AddPurpleRoot(CCGraphBuilder& aBuilder, void* aRoot,
+              nsCycleCollectionParticipant* aParti)
+{
+  return aBuilder.AddPurpleRoot(aRoot, aParti);
+}
+
+// MayHaveChild() will be false after a Traverse if the object does
+// not have any children the CC will visit.
+class ChildFinder : public nsCycleCollectionTraversalCallback
+{
+public:
+  ChildFinder() : mMayHaveChild(false)
+  {
+  }
+
+  // The logic of the Note*Child functions must mirror that of their
+  // respective functions in CCGraphBuilder.
+  NS_IMETHOD_(void) NoteXPCOMChild(nsISupports* aChild);
+  NS_IMETHOD_(void) NoteNativeChild(void* aChild,
+                                    nsCycleCollectionParticipant* aHelper);
+  NS_IMETHOD_(void) NoteJSChild(const JS::GCCellPtr& aThing);
+
+  NS_IMETHOD_(void) DescribeRefCountedNode(nsrefcnt aRefcount,
+                                           const char* aObjname)
+  {
+  }
+  NS_IMETHOD_(void) DescribeGCedNode(bool aIsMarked,
+                                     const char* aObjname,
+                                     uint64_t aCompartmentAddress)
+  {
+  }
+  NS_IMETHOD_(void) NoteNextEdgeName(const char* aName)
+  {
+  }
+  bool MayHaveChild()
+  {
+    return mMayHaveChild;
+  }
+private:
+  bool mMayHaveChild;
+};
+
+NS_IMETHODIMP_(void)
+ChildFinder::NoteXPCOMChild(nsISupports* aChild)
+{
+  if (!aChild || !(aChild = CanonicalizeXPCOMParticipant(aChild))) {
+    return;
+  }
+  nsXPCOMCycleCollectionParticipant* cp;
+  ToParticipant(aChild, &cp);
+  if (cp && !cp->CanSkip(aChild, true)) {
+    mMayHaveChild = true;
+  }
+}
+
+NS_IMETHODIMP_(void)
+ChildFinder::NoteNativeChild(void* aChild,
+                             nsCycleCollectionParticipant* aHelper)
+{
+  if (!aChild) {
+    return;
+  }
+  MOZ_ASSERT(aHelper, "Native child must have a participant");
+  if (!aHelper->CanSkip(aChild, true)) {
+    mMayHaveChild = true;
+  }
+}
+
+NS_IMETHODIMP_(void)
+ChildFinder::NoteJSChild(const JS::GCCellPtr& aChild)
+{
+  if (aChild && JS::GCThingIsMarkedGray(aChild)) {
+    mMayHaveChild = true;
+  }
+}
+
+static bool
+MayHaveChild(void* aObj, nsCycleCollectionParticipant* aCp)
+{
+  ChildFinder cf;
+  aCp->Traverse(aObj, cf);
+  return cf.MayHaveChild();
+}
+
+// JSPurpleBuffer keeps references to GCThings which might affect the
+// next cycle collection. It is owned only by itself and during unlink its
+// self reference is broken down and the object ends up killing itself.
+// If GC happens before CC, references to GCthings and the self reference are
+// removed.
+class JSPurpleBuffer
+{
+  ~JSPurpleBuffer()
+  {
+    MOZ_ASSERT(mValues.IsEmpty());
+    MOZ_ASSERT(mObjects.IsEmpty());
+  }
+
+public:
+  explicit JSPurpleBuffer(RefPtr<JSPurpleBuffer>& aReferenceToThis)
+    : mReferenceToThis(aReferenceToThis)
+    , mValues(kSegmentSize)
+    , mObjects(kSegmentSize)
+  {
+    mReferenceToThis = this;
+    mozilla::HoldJSObjects(this);
+  }
+
+  void Destroy()
+  {
+    mReferenceToThis = nullptr;
+    mValues.Clear();
+    mObjects.Clear();
+    mozilla::DropJSObjects(this);
+  }
+
+  NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(JSPurpleBuffer)
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_NATIVE_CLASS(JSPurpleBuffer)
+
+  RefPtr<JSPurpleBuffer>& mReferenceToThis;
+
+  // These are raw pointers instead of Heap<T> because we only need Heap<T> for
+  // pointers which may point into the nursery. The purple buffer never contains
+  // pointers to the nursery because nursery gcthings can never be gray and only
+  // gray things can be inserted into the purple buffer.
+  static const size_t kSegmentSize = 512;
+  SegmentedVector<JS::Value, kSegmentSize, InfallibleAllocPolicy> mValues;
+  SegmentedVector<JSObject*, kSegmentSize, InfallibleAllocPolicy> mObjects;
+};
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(JSPurpleBuffer)
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(JSPurpleBuffer)
+  tmp->Destroy();
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(JSPurpleBuffer)
+  CycleCollectionNoteChild(cb, tmp, "self");
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+#define NS_TRACE_SEGMENTED_ARRAY(_field, _type)                               \
+  {                                                                           \
+    for (auto iter = tmp->_field.Iter(); !iter.Done(); iter.Next()) {         \
+      js::gc::CallTraceCallbackOnNonHeap<_type, TraceCallbacks>(              \
+          &iter.Get(), aCallbacks, #_field, aClosure);                        \
+    }                                                                         \
+  }
+
+NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(JSPurpleBuffer)
+  NS_TRACE_SEGMENTED_ARRAY(mValues, JS::Value)
+  NS_TRACE_SEGMENTED_ARRAY(mObjects, JSObject*)
+NS_IMPL_CYCLE_COLLECTION_TRACE_END
+
+NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(JSPurpleBuffer, AddRef)
+NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(JSPurpleBuffer, Release)
+
+class SnowWhiteKiller : public TraceCallbacks
+{
+  struct SnowWhiteObject
+  {
+    void* mPointer;
+    nsCycleCollectionParticipant* mParticipant;
+    nsCycleCollectingAutoRefCnt* mRefCnt;
+  };
+
+  // Segments are 4 KiB on 32-bit and 8 KiB on 64-bit.
+  static const size_t kSegmentSize = sizeof(void*) * 1024;
+  typedef SegmentedVector<SnowWhiteObject, kSegmentSize, InfallibleAllocPolicy>
+    ObjectsVector;
+
+public:
+  explicit SnowWhiteKiller(nsCycleCollector* aCollector)
+    : mCollector(aCollector)
+    , mObjects(kSegmentSize)
+  {
+    MOZ_ASSERT(mCollector, "Calling SnowWhiteKiller after nsCC went away");
+  }
+
+  ~SnowWhiteKiller()
+  {
+    for (auto iter = mObjects.Iter(); !iter.Done(); iter.Next()) {
+      SnowWhiteObject& o = iter.Get();
+      if (!o.mRefCnt->get() && !o.mRefCnt->IsInPurpleBuffer()) {
+        mCollector->RemoveObjectFromGraph(o.mPointer);
+        o.mRefCnt->stabilizeForDeletion();
+        {
+          JS::AutoEnterCycleCollection autocc(mCollector->Context()->Context());
+          o.mParticipant->Trace(o.mPointer, *this, nullptr);
+        }
+        o.mParticipant->DeleteCycleCollectable(o.mPointer);
+      }
+    }
+  }
+
+  void
+  Visit(nsPurpleBuffer& aBuffer, nsPurpleBufferEntry* aEntry)
+  {
+    MOZ_ASSERT(aEntry->mObject, "Null object in purple buffer");
+    if (!aEntry->mRefCnt->get()) {
+      void* o = aEntry->mObject;
+      nsCycleCollectionParticipant* cp = aEntry->mParticipant;
+      CanonicalizeParticipant(&o, &cp);
+      SnowWhiteObject swo = { o, cp, aEntry->mRefCnt };
+      mObjects.InfallibleAppend(swo);
+      aBuffer.Remove(aEntry);
+    }
+  }
+
+  bool HasSnowWhiteObjects() const
+  {
+    return !mObjects.IsEmpty();
+  }
+
+  virtual void Trace(JS::Heap<JS::Value>* aValue, const char* aName,
+                     void* aClosure) const override
+  {
+    const JS::Value& val = aValue->unbarrieredGet();
+    if (val.isMarkable() && ValueIsGrayCCThing(val)) {
+      MOZ_ASSERT(!js::gc::IsInsideNursery(val.toGCThing()));
+      mCollector->GetJSPurpleBuffer()->mValues.InfallibleAppend(val);
+    }
+  }
+
+  virtual void Trace(JS::Heap<jsid>* aId, const char* aName,
+                     void* aClosure) const override
+  {
+  }
+
+  void AppendJSObjectToPurpleBuffer(JSObject* obj) const
+  {
+    if (obj && JS::ObjectIsMarkedGray(obj)) {
+      MOZ_ASSERT(JS::ObjectIsTenured(obj));
+      mCollector->GetJSPurpleBuffer()->mObjects.InfallibleAppend(obj);
+    }
+  }
+
+  virtual void Trace(JS::Heap<JSObject*>* aObject, const char* aName,
+                     void* aClosure) const override
+  {
+    AppendJSObjectToPurpleBuffer(aObject->unbarrieredGet());
+  }
+
+  virtual void Trace(JSObject** aObject, const char* aName,
+                     void* aClosure) const override
+  {
+    AppendJSObjectToPurpleBuffer(*aObject);
+  }
+
+  virtual void Trace(JS::TenuredHeap<JSObject*>* aObject, const char* aName,
+                     void* aClosure) const override
+  {
+    AppendJSObjectToPurpleBuffer(aObject->unbarrieredGetPtr());
+  }
+
+  virtual void Trace(JS::Heap<JSString*>* aString, const char* aName,
+                     void* aClosure) const override
+  {
+  }
+
+  virtual void Trace(JS::Heap<JSScript*>* aScript, const char* aName,
+                     void* aClosure) const override
+  {
+  }
+
+  virtual void Trace(JS::Heap<JSFunction*>* aFunction, const char* aName,
+                     void* aClosure) const override
+  {
+  }
+
+private:
+  RefPtr<nsCycleCollector> mCollector;
+  ObjectsVector mObjects;
+};
+
+class RemoveSkippableVisitor : public SnowWhiteKiller
+{
+public:
+  RemoveSkippableVisitor(nsCycleCollector* aCollector,
+                         bool aRemoveChildlessNodes,
+                         bool aAsyncSnowWhiteFreeing,
+                         CC_ForgetSkippableCallback aCb)
+    : SnowWhiteKiller(aCollector)
+    , mRemoveChildlessNodes(aRemoveChildlessNodes)
+    , mAsyncSnowWhiteFreeing(aAsyncSnowWhiteFreeing)
+    , mDispatchedDeferredDeletion(false)
+    , mCallback(aCb)
+  {
+  }
+
+  ~RemoveSkippableVisitor()
+  {
+    // Note, we must call the callback before SnowWhiteKiller calls
+    // DeleteCycleCollectable!
+    if (mCallback) {
+      mCallback();
+    }
+    if (HasSnowWhiteObjects()) {
+      // Effectively a continuation.
+      nsCycleCollector_dispatchDeferredDeletion(true);
+    }
+  }
+
+  void
+  Visit(nsPurpleBuffer& aBuffer, nsPurpleBufferEntry* aEntry)
+  {
+    MOZ_ASSERT(aEntry->mObject, "null mObject in purple buffer");
+    if (!aEntry->mRefCnt->get()) {
+      if (!mAsyncSnowWhiteFreeing) {
+        SnowWhiteKiller::Visit(aBuffer, aEntry);
+      } else if (!mDispatchedDeferredDeletion) {
+        mDispatchedDeferredDeletion = true;
+        nsCycleCollector_dispatchDeferredDeletion(false);
+      }
+      return;
+    }
+    void* o = aEntry->mObject;
+    nsCycleCollectionParticipant* cp = aEntry->mParticipant;
+    CanonicalizeParticipant(&o, &cp);
+    if (aEntry->mRefCnt->IsPurple() && !cp->CanSkip(o, false) &&
+        (!mRemoveChildlessNodes || MayHaveChild(o, cp))) {
+      return;
+    }
+    aBuffer.Remove(aEntry);
+  }
+
+private:
+  bool mRemoveChildlessNodes;
+  bool mAsyncSnowWhiteFreeing;
+  bool mDispatchedDeferredDeletion;
+  CC_ForgetSkippableCallback mCallback;
+};
+
+void
+nsPurpleBuffer::RemoveSkippable(nsCycleCollector* aCollector,
+                                bool aRemoveChildlessNodes,
+                                bool aAsyncSnowWhiteFreeing,
+                                CC_ForgetSkippableCallback aCb)
+{
+  RemoveSkippableVisitor visitor(aCollector, aRemoveChildlessNodes,
+                                 aAsyncSnowWhiteFreeing, aCb);
+  VisitEntries(visitor);
+}
+
+bool
+nsCycleCollector::FreeSnowWhite(bool aUntilNoSWInPurpleBuffer)
+{
+  CheckThreadSafety();
+
+  if (mFreeingSnowWhite) {
+    return false;
+  }
+
+  AutoRestore<bool> ar(mFreeingSnowWhite);
+  mFreeingSnowWhite = true;
+
+  bool hadSnowWhiteObjects = false;
+  do {
+    SnowWhiteKiller visitor(this);
+    mPurpleBuf.VisitEntries(visitor);
+    hadSnowWhiteObjects = hadSnowWhiteObjects ||
+                          visitor.HasSnowWhiteObjects();
+    if (!visitor.HasSnowWhiteObjects()) {
+      break;
+    }
+  } while (aUntilNoSWInPurpleBuffer);
+  return hadSnowWhiteObjects;
+}
+
+void
+nsCycleCollector::ForgetSkippable(bool aRemoveChildlessNodes,
+                                  bool aAsyncSnowWhiteFreeing)
+{
+  CheckThreadSafety();
+
+  mozilla::Maybe<mozilla::AutoGlobalTimelineMarker> marker;
+  if (NS_IsMainThread()) {
+    marker.emplace("nsCycleCollector::ForgetSkippable", MarkerStackRequest::NO_STACK);
+  }
+
+  // If we remove things from the purple buffer during graph building, we may
+  // lose track of an object that was mutated during graph building.
+  MOZ_ASSERT(IsIdle());
+
+  if (mJSContext) {
+    mJSContext->PrepareForForgetSkippable();
+  }
+  MOZ_ASSERT(!mScanInProgress,
+             "Don't forget skippable or free snow-white while scan is in progress.");
+  mPurpleBuf.RemoveSkippable(this, aRemoveChildlessNodes,
+                             aAsyncSnowWhiteFreeing, mForgetSkippableCB);
+}
+
+MOZ_NEVER_INLINE void
+nsCycleCollector::MarkRoots(SliceBudget& aBudget)
+{
+  JS::AutoAssertNoGC nogc;
+  TimeLog timeLog;
+  AutoRestore<bool> ar(mScanInProgress);
+  MOZ_RELEASE_ASSERT(!mScanInProgress);
+  mScanInProgress = true;
+  MOZ_ASSERT(mIncrementalPhase == GraphBuildingPhase);
+
+  JS::AutoEnterCycleCollection autocc(Context()->Context());
+  bool doneBuilding = mBuilder->BuildGraph(aBudget);
+
+  if (!doneBuilding) {
+    timeLog.Checkpoint("MarkRoots()");
+    return;
+  }
+
+  mBuilder = nullptr;
+  mIncrementalPhase = ScanAndCollectWhitePhase;
+  timeLog.Checkpoint("MarkRoots()");
+}
+
+
+////////////////////////////////////////////////////////////////////////
+// Bacon & Rajan's |ScanRoots| routine.
+////////////////////////////////////////////////////////////////////////
+
+
+struct ScanBlackVisitor
+{
+  ScanBlackVisitor(uint32_t& aWhiteNodeCount, bool& aFailed)
+    : mWhiteNodeCount(aWhiteNodeCount), mFailed(aFailed)
+  {
+  }
+
+  bool ShouldVisitNode(PtrInfo const* aPi)
+  {
+    return aPi->mColor != black;
+  }
+
+  MOZ_NEVER_INLINE void VisitNode(PtrInfo* aPi)
+  {
+    if (aPi->mColor == white) {
+      --mWhiteNodeCount;
+    }
+    aPi->mColor = black;
+  }
+
+  void Failed()
+  {
+    mFailed = true;
+  }
+
+private:
+  uint32_t& mWhiteNodeCount;
+  bool& mFailed;
+};
+
+static void
+FloodBlackNode(uint32_t& aWhiteNodeCount, bool& aFailed, PtrInfo* aPi)
+{
+  GraphWalker<ScanBlackVisitor>(ScanBlackVisitor(aWhiteNodeCount,
+                                                 aFailed)).Walk(aPi);
+  MOZ_ASSERT(aPi->mColor == black || !aPi->WasTraversed(),
+             "FloodBlackNode should make aPi black");
+}
+
+// Iterate over the WeakMaps.  If we mark anything while iterating
+// over the WeakMaps, we must iterate over all of the WeakMaps again.
+void
+nsCycleCollector::ScanWeakMaps()
+{
+  bool anyChanged;
+  bool failed = false;
+  do {
+    anyChanged = false;
+    for (uint32_t i = 0; i < mGraph.mWeakMaps.Length(); i++) {
+      WeakMapping* wm = &mGraph.mWeakMaps[i];
+
+      // If any of these are null, the original object was marked black.
+      uint32_t mColor = wm->mMap ? wm->mMap->mColor : black;
+      uint32_t kColor = wm->mKey ? wm->mKey->mColor : black;
+      uint32_t kdColor = wm->mKeyDelegate ? wm->mKeyDelegate->mColor : black;
+      uint32_t vColor = wm->mVal ? wm->mVal->mColor : black;
+
+      MOZ_ASSERT(mColor != grey, "Uncolored weak map");
+      MOZ_ASSERT(kColor != grey, "Uncolored weak map key");
+      MOZ_ASSERT(kdColor != grey, "Uncolored weak map key delegate");
+      MOZ_ASSERT(vColor != grey, "Uncolored weak map value");
+
+      if (mColor == black && kColor != black && kdColor == black) {
+        FloodBlackNode(mWhiteNodeCount, failed, wm->mKey);
+        anyChanged = true;
+      }
+
+      if (mColor == black && kColor == black && vColor != black) {
+        FloodBlackNode(mWhiteNodeCount, failed, wm->mVal);
+        anyChanged = true;
+      }
+    }
+  } while (anyChanged);
+
+  if (failed) {
+    MOZ_ASSERT(false, "Ran out of memory in ScanWeakMaps");
+    CC_TELEMETRY(_OOM, true);
+  }
+}
+
+// Flood black from any objects in the purple buffer that are in the CC graph.
+class PurpleScanBlackVisitor
+{
+public:
+  PurpleScanBlackVisitor(CCGraph& aGraph, nsCycleCollectorLogger* aLogger,
+                         uint32_t& aCount, bool& aFailed)
+    : mGraph(aGraph), mLogger(aLogger), mCount(aCount), mFailed(aFailed)
+  {
+  }
+
+  void
+  Visit(nsPurpleBuffer& aBuffer, nsPurpleBufferEntry* aEntry)
+  {
+    MOZ_ASSERT(aEntry->mObject,
+               "Entries with null mObject shouldn't be in the purple buffer.");
+    MOZ_ASSERT(aEntry->mRefCnt->get() != 0,
+               "Snow-white objects shouldn't be in the purple buffer.");
+
+    void* obj = aEntry->mObject;
+    if (!aEntry->mParticipant) {
+      obj = CanonicalizeXPCOMParticipant(static_cast<nsISupports*>(obj));
+      MOZ_ASSERT(obj, "Don't add objects that don't participate in collection!");
+    }
+
+    PtrInfo* pi = mGraph.FindNode(obj);
+    if (!pi) {
+      return;
+    }
+    MOZ_ASSERT(pi->mParticipant, "No dead objects should be in the purple buffer.");
+    if (MOZ_UNLIKELY(mLogger)) {
+      mLogger->NoteIncrementalRoot((uint64_t)pi->mPointer);
+    }
+    if (pi->mColor == black) {
+      return;
+    }
+    FloodBlackNode(mCount, mFailed, pi);
+  }
+
+private:
+  CCGraph& mGraph;
+  RefPtr<nsCycleCollectorLogger> mLogger;
+  uint32_t& mCount;
+  bool& mFailed;
+};
+
+// Objects that have been stored somewhere since the start of incremental graph building must
+// be treated as live for this cycle collection, because we may not have accurate information
+// about who holds references to them.
+void
+nsCycleCollector::ScanIncrementalRoots()
+{
+  TimeLog timeLog;
+
+  // Reference counted objects:
+  // We cleared the purple buffer at the start of the current ICC, so if a
+  // refcounted object is purple, it may have been AddRef'd during the current
+  // ICC. (It may also have only been released.) If that is the case, we cannot
+  // be sure that the set of things pointing to the object in the CC graph
+  // is accurate. Therefore, for safety, we treat any purple objects as being
+  // live during the current CC. We don't remove anything from the purple
+  // buffer here, so these objects will be suspected and freed in the next CC
+  // if they are garbage.
+  bool failed = false;
+  PurpleScanBlackVisitor purpleScanBlackVisitor(mGraph, mLogger,
+                                                mWhiteNodeCount, failed);
+  mPurpleBuf.VisitEntries(purpleScanBlackVisitor);
+  timeLog.Checkpoint("ScanIncrementalRoots::fix purple");
+
+  bool hasJSContext = !!mJSContext;
+  nsCycleCollectionParticipant* jsParticipant =
+    hasJSContext ? mJSContext->GCThingParticipant() : nullptr;
+  nsCycleCollectionParticipant* zoneParticipant =
+    hasJSContext ? mJSContext->ZoneParticipant() : nullptr;
+  bool hasLogger = !!mLogger;
+
+  NodePool::Enumerator etor(mGraph.mNodes);
+  while (!etor.IsDone()) {
+    PtrInfo* pi = etor.GetNext();
+
+    // As an optimization, if an object has already been determined to be live,
+    // don't consider it further.  We can't do this if there is a listener,
+    // because the listener wants to know the complete set of incremental roots.
+    if (pi->mColor == black && MOZ_LIKELY(!hasLogger)) {
+      continue;
+    }
+
+    // Garbage collected objects:
+    // If a GCed object was added to the graph with a refcount of zero, and is
+    // now marked black by the GC, it was probably gray before and was exposed
+    // to active JS, so it may have been stored somewhere, so it needs to be
+    // treated as live.
+    if (pi->IsGrayJS() && MOZ_LIKELY(hasJSContext)) {
+      // If the object is still marked gray by the GC, nothing could have gotten
+      // hold of it, so it isn't an incremental root.
+      if (pi->mParticipant == jsParticipant) {
+        JS::GCCellPtr ptr(pi->mPointer, JS::GCThingTraceKind(pi->mPointer));
+        if (GCThingIsGrayCCThing(ptr)) {
+          continue;
+        }
+      } else if (pi->mParticipant == zoneParticipant) {
+        JS::Zone* zone = static_cast<JS::Zone*>(pi->mPointer);
+        if (js::ZoneGlobalsAreAllGray(zone)) {
+          continue;
+        }
+      } else {
+        MOZ_ASSERT(false, "Non-JS thing with 0 refcount? Treating as live.");
+      }
+    } else if (!pi->mParticipant && pi->WasTraversed()) {
+      // Dead traversed refcounted objects:
+      // If the object was traversed, it must have been alive at the start of
+      // the CC, and thus had a positive refcount. It is dead now, so its
+      // refcount must have decreased at some point during the CC. Therefore,
+      // it would be in the purple buffer if it wasn't dead, so treat it as an
+      // incremental root.
+      //
+      // This should not cause leaks because as the object died it should have
+      // released anything it held onto, which will add them to the purple
+      // buffer, which will cause them to be considered in the next CC.
+    } else {
+      continue;
+    }
+
+    // At this point, pi must be an incremental root.
+
+    // If there's a listener, tell it about this root. We don't bother with the
+    // optimization of skipping the Walk() if pi is black: it will just return
+    // without doing anything and there's no need to make this case faster.
+    if (MOZ_UNLIKELY(hasLogger) && pi->mPointer) {
+      // Dead objects aren't logged. See bug 1031370.
+      mLogger->NoteIncrementalRoot((uint64_t)pi->mPointer);
+    }
+
+    FloodBlackNode(mWhiteNodeCount, failed, pi);
+  }
+
+  timeLog.Checkpoint("ScanIncrementalRoots::fix nodes");
+
+  if (failed) {
+    NS_ASSERTION(false, "Ran out of memory in ScanIncrementalRoots");
+    CC_TELEMETRY(_OOM, true);
+  }
+}
+
+// Mark nodes white and make sure their refcounts are ok.
+// No nodes are marked black during this pass to ensure that refcount
+// checking is run on all nodes not marked black by ScanIncrementalRoots.
+void
+nsCycleCollector::ScanWhiteNodes(bool aFullySynchGraphBuild)
+{
+  NodePool::Enumerator nodeEnum(mGraph.mNodes);
+  while (!nodeEnum.IsDone()) {
+    PtrInfo* pi = nodeEnum.GetNext();
+    if (pi->mColor == black) {
+      // Incremental roots can be in a nonsensical state, so don't
+      // check them. This will miss checking nodes that are merely
+      // reachable from incremental roots.
+      MOZ_ASSERT(!aFullySynchGraphBuild,
+                 "In a synch CC, no nodes should be marked black early on.");
+      continue;
+    }
+    MOZ_ASSERT(pi->mColor == grey);
+
+    if (!pi->WasTraversed()) {
+      // This node was deleted before it was traversed, so there's no reason
+      // to look at it.
+      MOZ_ASSERT(!pi->mParticipant, "Live nodes should all have been traversed");
+      continue;
+    }
+
+    if (pi->mInternalRefs == pi->mRefCount || pi->IsGrayJS()) {
+      pi->mColor = white;
+      ++mWhiteNodeCount;
+      continue;
+    }
+
+    if (pi->mInternalRefs > pi->mRefCount) {
+#ifdef MOZ_CRASHREPORTER
+      const char* piName = "Unknown";
+      if (pi->mParticipant) {
+        piName = pi->mParticipant->ClassName();
+      }
+      nsPrintfCString msg("More references to an object than its refcount, for class %s", piName);
+      CrashReporter::AnnotateCrashReport(NS_LITERAL_CSTRING("CycleCollector"), msg);
+#endif
+      MOZ_CRASH();
+    }
+
+    // This node will get marked black in the next pass.
+  }
+}
+
+// Any remaining grey nodes that haven't already been deleted must be alive,
+// so mark them and their children black. Any nodes that are black must have
+// already had their children marked black, so there's no need to look at them
+// again. This pass may turn some white nodes to black.
+void
+nsCycleCollector::ScanBlackNodes()
+{
+  bool failed = false;
+  NodePool::Enumerator nodeEnum(mGraph.mNodes);
+  while (!nodeEnum.IsDone()) {
+    PtrInfo* pi = nodeEnum.GetNext();
+    if (pi->mColor == grey && pi->WasTraversed()) {
+      FloodBlackNode(mWhiteNodeCount, failed, pi);
+    }
+  }
+
+  if (failed) {
+    NS_ASSERTION(false, "Ran out of memory in ScanBlackNodes");
+    CC_TELEMETRY(_OOM, true);
+  }
+}
+
+void
+nsCycleCollector::ScanRoots(bool aFullySynchGraphBuild)
+{
+  JS::AutoAssertNoGC nogc;
+  AutoRestore<bool> ar(mScanInProgress);
+  MOZ_RELEASE_ASSERT(!mScanInProgress);
+  mScanInProgress = true;
+  mWhiteNodeCount = 0;
+  MOZ_ASSERT(mIncrementalPhase == ScanAndCollectWhitePhase);
+
+  JS::AutoEnterCycleCollection autocc(Context()->Context());
+
+  if (!aFullySynchGraphBuild) {
+    ScanIncrementalRoots();
+  }
+
+  TimeLog timeLog;
+  ScanWhiteNodes(aFullySynchGraphBuild);
+  timeLog.Checkpoint("ScanRoots::ScanWhiteNodes");
+
+  ScanBlackNodes();
+  timeLog.Checkpoint("ScanRoots::ScanBlackNodes");
+
+  // Scanning weak maps must be done last.
+  ScanWeakMaps();
+  timeLog.Checkpoint("ScanRoots::ScanWeakMaps");
+
+  if (mLogger) {
+    mLogger->BeginResults();
+
+    NodePool::Enumerator etor(mGraph.mNodes);
+    while (!etor.IsDone()) {
+      PtrInfo* pi = etor.GetNext();
+      if (!pi->WasTraversed()) {
+        continue;
+      }
+      switch (pi->mColor) {
+        case black:
+          if (!pi->IsGrayJS() && !pi->IsBlackJS() &&
+              pi->mInternalRefs != pi->mRefCount) {
+            mLogger->DescribeRoot((uint64_t)pi->mPointer,
+                                  pi->mInternalRefs);
+          }
+          break;
+        case white:
+          mLogger->DescribeGarbage((uint64_t)pi->mPointer);
+          break;
+        case grey:
+          MOZ_ASSERT(false, "All traversed objects should be black or white");
+          break;
+      }
+    }
+
+    mLogger->End();
+    mLogger = nullptr;
+    timeLog.Checkpoint("ScanRoots::listener");
+  }
+}
+
+
+////////////////////////////////////////////////////////////////////////
+// Bacon & Rajan's |CollectWhite| routine, somewhat modified.
+////////////////////////////////////////////////////////////////////////
+
+bool
+nsCycleCollector::CollectWhite()
+{
+  // Explanation of "somewhat modified": we have no way to collect the
+  // set of whites "all at once", we have to ask each of them to drop
+  // their outgoing links and assume this will cause the garbage cycle
+  // to *mostly* self-destruct (except for the reference we continue
+  // to hold).
+  //
+  // To do this "safely" we must make sure that the white nodes we're
+  // operating on are stable for the duration of our operation. So we
+  // make 3 sets of calls to language runtimes:
+  //
+  //   - Root(whites), which should pin the whites in memory.
+  //   - Unlink(whites), which drops outgoing links on each white.
+  //   - Unroot(whites), which returns the whites to normal GC.
+
+  // Segments are 4 KiB on 32-bit and 8 KiB on 64-bit.
+  static const size_t kSegmentSize = sizeof(void*) * 1024;
+  SegmentedVector<PtrInfo*, kSegmentSize, InfallibleAllocPolicy>
+    whiteNodes(kSegmentSize);
+  TimeLog timeLog;
+
+  MOZ_ASSERT(mIncrementalPhase == ScanAndCollectWhitePhase);
+
+  uint32_t numWhiteNodes = 0;
+  uint32_t numWhiteGCed = 0;
+  uint32_t numWhiteJSZones = 0;
+
+  {
+    JS::AutoAssertNoGC nogc;
+    bool hasJSContext = !!mJSContext;
+    nsCycleCollectionParticipant* zoneParticipant =
+      hasJSContext ? mJSContext->ZoneParticipant() : nullptr;
+
+    NodePool::Enumerator etor(mGraph.mNodes);
+    while (!etor.IsDone()) {
+      PtrInfo* pinfo = etor.GetNext();
+      if (pinfo->mColor == white && pinfo->mParticipant) {
+        if (pinfo->IsGrayJS()) {
+          MOZ_ASSERT(mJSContext);
+          ++numWhiteGCed;
+          JS::Zone* zone;
+          if (MOZ_UNLIKELY(pinfo->mParticipant == zoneParticipant)) {
+            ++numWhiteJSZones;
+            zone = static_cast<JS::Zone*>(pinfo->mPointer);
+          } else {
+            JS::GCCellPtr ptr(pinfo->mPointer, JS::GCThingTraceKind(pinfo->mPointer));
+            zone = JS::GetTenuredGCThingZone(ptr);
+          }
+          mJSContext->AddZoneWaitingForGC(zone);
+        } else {
+          whiteNodes.InfallibleAppend(pinfo);
+          pinfo->mParticipant->Root(pinfo->mPointer);
+          ++numWhiteNodes;
+        }
+      }
+    }
+  }
+
+  mResults.mFreedRefCounted += numWhiteNodes;
+  mResults.mFreedGCed += numWhiteGCed;
+  mResults.mFreedJSZones += numWhiteJSZones;
+
+  timeLog.Checkpoint("CollectWhite::Root");
+
+  if (mBeforeUnlinkCB) {
+    mBeforeUnlinkCB();
+    timeLog.Checkpoint("CollectWhite::BeforeUnlinkCB");
+  }
+
+  // Unlink() can trigger a GC, so do not touch any JS or anything
+  // else not in whiteNodes after here.
+
+  for (auto iter = whiteNodes.Iter(); !iter.Done(); iter.Next()) {
+    PtrInfo* pinfo = iter.Get();
+    MOZ_ASSERT(pinfo->mParticipant,
+               "Unlink shouldn't see objects removed from graph.");
+    pinfo->mParticipant->Unlink(pinfo->mPointer);
+#ifdef DEBUG
+    if (mJSContext) {
+      mJSContext->AssertNoObjectsToTrace(pinfo->mPointer);
+    }
+#endif
+  }
+  timeLog.Checkpoint("CollectWhite::Unlink");
+
+  JS::AutoAssertNoGC nogc;
+  for (auto iter = whiteNodes.Iter(); !iter.Done(); iter.Next()) {
+    PtrInfo* pinfo = iter.Get();
+    MOZ_ASSERT(pinfo->mParticipant,
+               "Unroot shouldn't see objects removed from graph.");
+    pinfo->mParticipant->Unroot(pinfo->mPointer);
+  }
+  timeLog.Checkpoint("CollectWhite::Unroot");
+
+  nsCycleCollector_dispatchDeferredDeletion(false, true);
+  timeLog.Checkpoint("CollectWhite::dispatchDeferredDeletion");
+
+  mIncrementalPhase = CleanupPhase;
+
+  return numWhiteNodes > 0 || numWhiteGCed > 0 || numWhiteJSZones > 0;
+}
+
+
+////////////////////////
+// Memory reporting
+////////////////////////
+
+MOZ_DEFINE_MALLOC_SIZE_OF(CycleCollectorMallocSizeOf)
+
+NS_IMETHODIMP
+nsCycleCollector::CollectReports(nsIHandleReportCallback* aHandleReport,
+                                 nsISupports* aData, bool aAnonymize)
+{
+  size_t objectSize, graphSize, purpleBufferSize;
+  SizeOfIncludingThis(CycleCollectorMallocSizeOf,
+                      &objectSize, &graphSize,
+                      &purpleBufferSize);
+
+  if (objectSize > 0) {
+    MOZ_COLLECT_REPORT(
+      "explicit/cycle-collector/collector-object", KIND_HEAP, UNITS_BYTES,
+      objectSize,
+      "Memory used for the cycle collector object itself.");
+  }
+
+  if (graphSize > 0) {
+    MOZ_COLLECT_REPORT(
+      "explicit/cycle-collector/graph", KIND_HEAP, UNITS_BYTES,
+      graphSize,
+      "Memory used for the cycle collector's graph. This should be zero when "
+      "the collector is idle.");
+  }
+
+  if (purpleBufferSize > 0) {
+    MOZ_COLLECT_REPORT(
+      "explicit/cycle-collector/purple-buffer", KIND_HEAP, UNITS_BYTES,
+      purpleBufferSize,
+      "Memory used for the cycle collector's purple buffer.");
+  }
+
+  return NS_OK;
+};
+
+
+////////////////////////////////////////////////////////////////////////
+// Collector implementation
+////////////////////////////////////////////////////////////////////////
+
+nsCycleCollector::nsCycleCollector() :
+  mActivelyCollecting(false),
+  mFreeingSnowWhite(false),
+  mScanInProgress(false),
+  mJSContext(nullptr),
+  mIncrementalPhase(IdlePhase),
+#ifdef DEBUG
+  mThread(NS_GetCurrentThread()),
+#endif
+  mWhiteNodeCount(0),
+  mBeforeUnlinkCB(nullptr),
+  mForgetSkippableCB(nullptr),
+  mUnmergedNeeded(0),
+  mMergedInARow(0)
+{
+}
+
+nsCycleCollector::~nsCycleCollector()
+{
+  UnregisterWeakMemoryReporter(this);
+}
+
+void
+nsCycleCollector::RegisterJSContext(CycleCollectedJSContext* aJSContext)
+{
+  MOZ_RELEASE_ASSERT(!mJSContext, "Multiple registrations of JS context in cycle collector");
+  mJSContext = aJSContext;
+
+  if (!NS_IsMainThread()) {
+    return;
+  }
+
+  // We can't register as a reporter in nsCycleCollector() because that runs
+  // before the memory reporter manager is initialized.  So we do it here
+  // instead.
+  RegisterWeakMemoryReporter(this);
+}
+
+void
+nsCycleCollector::ForgetJSContext()
+{
+  MOZ_RELEASE_ASSERT(mJSContext, "Forgetting JS context in cycle collector before a JS context was registered");
+  mJSContext = nullptr;
+}
+
+#ifdef DEBUG
+static bool
+HasParticipant(void* aPtr, nsCycleCollectionParticipant* aParti)
+{
+  if (aParti) {
+    return true;
+  }
+
+  nsXPCOMCycleCollectionParticipant* xcp;
+  ToParticipant(static_cast<nsISupports*>(aPtr), &xcp);
+  return xcp != nullptr;
+}
+#endif
+
+MOZ_ALWAYS_INLINE void
+nsCycleCollector::Suspect(void* aPtr, nsCycleCollectionParticipant* aParti,
+                          nsCycleCollectingAutoRefCnt* aRefCnt)
+{
+  CheckThreadSafety();
+
+  // Don't call AddRef or Release of a CCed object in a Traverse() method.
+  MOZ_ASSERT(!mScanInProgress, "Attempted to call Suspect() while a scan was in progress");
+
+  if (MOZ_UNLIKELY(mScanInProgress)) {
+    return;
+  }
+
+  MOZ_ASSERT(aPtr, "Don't suspect null pointers");
+
+  MOZ_ASSERT(HasParticipant(aPtr, aParti),
+             "Suspected nsISupports pointer must QI to nsXPCOMCycleCollectionParticipant");
+
+  mPurpleBuf.Put(aPtr, aParti, aRefCnt);
+}
+
+void
+nsCycleCollector::CheckThreadSafety()
+{
+#ifdef DEBUG
+  nsIThread* currentThread = NS_GetCurrentThread();
+  // XXXkhuey we can be called so late in shutdown that NS_GetCurrentThread
+  // returns null (after the thread manager has shut down)
+  MOZ_ASSERT(mThread == currentThread || !currentThread);
+#endif
+}
+
+// The cycle collector uses the mark bitmap to discover what JS objects
+// were reachable only from XPConnect roots that might participate in
+// cycles. We ask the JS context whether we need to force a GC before
+// this CC. It returns true on startup (before the mark bits have been set),
+// and also when UnmarkGray has run out of stack.  We also force GCs on shut
+// down to collect cycles involving both DOM and JS.
+void
+nsCycleCollector::FixGrayBits(bool aForceGC, TimeLog& aTimeLog)
+{
+  CheckThreadSafety();
+
+  if (!mJSContext) {
+    return;
+  }
+
+  if (!aForceGC) {
+    mJSContext->FixWeakMappingGrayBits();
+    aTimeLog.Checkpoint("FixWeakMappingGrayBits");
+
+    bool needGC = !mJSContext->AreGCGrayBitsValid();
+    // Only do a telemetry ping for non-shutdown CCs.
+    CC_TELEMETRY(_NEED_GC, needGC);
+    if (!needGC) {
+      return;
+    }
+    mResults.mForcedGC = true;
+  }
+
+  mJSContext->GarbageCollect(aForceGC ? JS::gcreason::SHUTDOWN_CC :
+                                        JS::gcreason::CC_FORCED);
+  aTimeLog.Checkpoint("FixGrayBits GC");
+}
+
+bool
+nsCycleCollector::IsIncrementalGCInProgress()
+{
+  return mJSContext && JS::IsIncrementalGCInProgress(mJSContext->Context());
+}
+
+void
+nsCycleCollector::FinishAnyIncrementalGCInProgress()
+{
+  if (IsIncrementalGCInProgress()) {
+    NS_WARNING("Finishing incremental GC in progress during CC");
+    JS::PrepareForIncrementalGC(mJSContext->Context());
+    JS::FinishIncrementalGC(mJSContext->Context(), JS::gcreason::CC_FORCED);
+  }
+}
+
+void
+nsCycleCollector::CleanupAfterCollection()
+{
+  TimeLog timeLog;
+  MOZ_ASSERT(mIncrementalPhase == CleanupPhase);
+  mGraph.Clear();
+  timeLog.Checkpoint("CleanupAfterCollection::mGraph.Clear()");
+
+  uint32_t interval =
+    (uint32_t)((TimeStamp::Now() - mCollectionStart).ToMilliseconds());
+#ifdef COLLECT_TIME_DEBUG
+  printf("cc: total cycle collector time was %ums in %u slices\n", interval,
+         mResults.mNumSlices);
+  printf("cc: visited %u ref counted and %u GCed objects, freed %d ref counted and %d GCed objects",
+         mResults.mVisitedRefCounted, mResults.mVisitedGCed,
+         mResults.mFreedRefCounted, mResults.mFreedGCed);
+  uint32_t numVisited = mResults.mVisitedRefCounted + mResults.mVisitedGCed;
+  if (numVisited > 1000) {
+    uint32_t numFreed = mResults.mFreedRefCounted + mResults.mFreedGCed;
+    printf(" (%d%%)", 100 * numFreed / numVisited);
+  }
+  printf(".\ncc: \n");
+#endif
+
+  CC_TELEMETRY( , interval);
+  CC_TELEMETRY(_VISITED_REF_COUNTED, mResults.mVisitedRefCounted);
+  CC_TELEMETRY(_VISITED_GCED, mResults.mVisitedGCed);
+  CC_TELEMETRY(_COLLECTED, mWhiteNodeCount);
+  timeLog.Checkpoint("CleanupAfterCollection::telemetry");
+
+  if (mJSContext) {
+    mJSContext->FinalizeDeferredThings(mResults.mAnyManual
+                                       ? CycleCollectedJSContext::FinalizeNow
+                                       : CycleCollectedJSContext::FinalizeIncrementally);
+    mJSContext->EndCycleCollectionCallback(mResults);
+    timeLog.Checkpoint("CleanupAfterCollection::EndCycleCollectionCallback()");
+  }
+  mIncrementalPhase = IdlePhase;
+}
+
+void
+nsCycleCollector::ShutdownCollect()
+{
+  FinishAnyIncrementalGCInProgress();
+
+  SliceBudget unlimitedBudget = SliceBudget::unlimited();
+  uint32_t i;
+  for (i = 0; i < DEFAULT_SHUTDOWN_COLLECTIONS; ++i) {
+    if (!Collect(ShutdownCC, unlimitedBudget, nullptr)) {
+      break;
+    }
+  }
+  NS_WARNING_ASSERTION(i < NORMAL_SHUTDOWN_COLLECTIONS, "Extra shutdown CC");
+}
+
+static void
+PrintPhase(const char* aPhase)
+{
+#ifdef DEBUG_PHASES
+  printf("cc: begin %s on %s\n", aPhase,
+         NS_IsMainThread() ? "mainthread" : "worker");
+#endif
+}
+
+bool
+nsCycleCollector::Collect(ccType aCCType,
+                          SliceBudget& aBudget,
+                          nsICycleCollectorListener* aManualListener,
+                          bool aPreferShorterSlices)
+{
+  CheckThreadSafety();
+
+  // This can legitimately happen in a few cases. See bug 383651.
+  if (mActivelyCollecting || mFreeingSnowWhite) {
+    return false;
+  }
+  mActivelyCollecting = true;
+
+  MOZ_ASSERT(!IsIncrementalGCInProgress());
+
+  mozilla::Maybe<mozilla::AutoGlobalTimelineMarker> marker;
+  if (NS_IsMainThread()) {
+    marker.emplace("nsCycleCollector::Collect", MarkerStackRequest::NO_STACK);
+  }
+
+  bool startedIdle = IsIdle();
+  bool collectedAny = false;
+
+  // If the CC started idle, it will call BeginCollection, which
+  // will do FreeSnowWhite, so it doesn't need to be done here.
+  if (!startedIdle) {
+    TimeLog timeLog;
+    FreeSnowWhite(true);
+    timeLog.Checkpoint("Collect::FreeSnowWhite");
+  }
+
+  if (aCCType != SliceCC) {
+    mResults.mAnyManual = true;
+  }
+
+  ++mResults.mNumSlices;
+
+  bool continueSlice = aBudget.isUnlimited() || !aPreferShorterSlices;
+  do {
+    switch (mIncrementalPhase) {
+      case IdlePhase:
+        PrintPhase("BeginCollection");
+        BeginCollection(aCCType, aManualListener);
+        break;
+      case GraphBuildingPhase:
+        PrintPhase("MarkRoots");
+        MarkRoots(aBudget);
+
+        // Only continue this slice if we're running synchronously or the
+        // next phase will probably be short, to reduce the max pause for this
+        // collection.
+        // (There's no need to check if we've finished graph building, because
+        // if we haven't, we've already exceeded our budget, and will finish
+        // this slice anyways.)
+        continueSlice = aBudget.isUnlimited() ||
+          (mResults.mNumSlices < 3 && !aPreferShorterSlices);
+        break;
+      case ScanAndCollectWhitePhase:
+        // We do ScanRoots and CollectWhite in a single slice to ensure
+        // that we won't unlink a live object if a weak reference is
+        // promoted to a strong reference after ScanRoots has finished.
+        // See bug 926533.
+        PrintPhase("ScanRoots");
+        ScanRoots(startedIdle);
+        PrintPhase("CollectWhite");
+        collectedAny = CollectWhite();
+        break;
+      case CleanupPhase:
+        PrintPhase("CleanupAfterCollection");
+        CleanupAfterCollection();
+        continueSlice = false;
+        break;
+    }
+    if (continueSlice) {
+      // Force SliceBudget::isOverBudget to check the time.
+      aBudget.step(SliceBudget::CounterReset);
+      continueSlice = !aBudget.isOverBudget();
+    }
+  } while (continueSlice);
+
+  // Clear mActivelyCollecting here to ensure that a recursive call to
+  // Collect() does something.
+  mActivelyCollecting = false;
+
+  if (aCCType != SliceCC && !startedIdle) {
+    // We were in the middle of an incremental CC (using its own listener).
+    // Somebody has forced a CC, so after having finished out the current CC,
+    // run the CC again using the new listener.
+    MOZ_ASSERT(IsIdle());
+    if (Collect(aCCType, aBudget, aManualListener)) {
+      collectedAny = true;
+    }
+  }
+
+  MOZ_ASSERT_IF(aCCType != SliceCC, IsIdle());
+
+  return collectedAny;
+}
+
+// Any JS objects we have in the graph could die when we GC, but we
+// don't want to abandon the current CC, because the graph contains
+// information about purple roots. So we synchronously finish off
+// the current CC.
+void
+nsCycleCollector::PrepareForGarbageCollection()
+{
+  if (IsIdle()) {
+    MOZ_ASSERT(mGraph.IsEmpty(), "Non-empty graph when idle");
+    MOZ_ASSERT(!mBuilder, "Non-null builder when idle");
+    if (mJSPurpleBuffer) {
+      mJSPurpleBuffer->Destroy();
+    }
+    return;
+  }
+
+  FinishAnyCurrentCollection();
+}
+
+void
+nsCycleCollector::FinishAnyCurrentCollection()
+{
+  if (IsIdle()) {
+    return;
+  }
+
+  SliceBudget unlimitedBudget = SliceBudget::unlimited();
+  PrintPhase("FinishAnyCurrentCollection");
+  // Use SliceCC because we only want to finish the CC in progress.
+  Collect(SliceCC, unlimitedBudget, nullptr);
+
+  // It is only okay for Collect() to have failed to finish the
+  // current CC if we're reentering the CC at some point past
+  // graph building. We need to be past the point where the CC will
+  // look at JS objects so that it is safe to GC.
+  MOZ_ASSERT(IsIdle() ||
+             (mActivelyCollecting && mIncrementalPhase != GraphBuildingPhase),
+             "Reentered CC during graph building");
+}
+
+// Don't merge too many times in a row, and do at least a minimum
+// number of unmerged CCs in a row.
+static const uint32_t kMinConsecutiveUnmerged = 3;
+static const uint32_t kMaxConsecutiveMerged = 3;
+
+bool
+nsCycleCollector::ShouldMergeZones(ccType aCCType)
+{
+  if (!mJSContext) {
+    return false;
+  }
+
+  MOZ_ASSERT(mUnmergedNeeded <= kMinConsecutiveUnmerged);
+  MOZ_ASSERT(mMergedInARow <= kMaxConsecutiveMerged);
+
+  if (mMergedInARow == kMaxConsecutiveMerged) {
+    MOZ_ASSERT(mUnmergedNeeded == 0);
+    mUnmergedNeeded = kMinConsecutiveUnmerged;
+  }
+
+  if (mUnmergedNeeded > 0) {
+    mUnmergedNeeded--;
+    mMergedInARow = 0;
+    return false;
+  }
+
+  if (aCCType == SliceCC && mJSContext->UsefulToMergeZones()) {
+    mMergedInARow++;
+    return true;
+  } else {
+    mMergedInARow = 0;
+    return false;
+  }
+}
+
+void
+nsCycleCollector::BeginCollection(ccType aCCType,
+                                  nsICycleCollectorListener* aManualListener)
+{
+  TimeLog timeLog;
+  MOZ_ASSERT(IsIdle());
+
+  mCollectionStart = TimeStamp::Now();
+
+  if (mJSContext) {
+    mJSContext->BeginCycleCollectionCallback();
+    timeLog.Checkpoint("BeginCycleCollectionCallback()");
+  }
+
+  bool isShutdown = (aCCType == ShutdownCC);
+
+  // Set up the listener for this CC.
+  MOZ_ASSERT_IF(isShutdown, !aManualListener);
+  MOZ_ASSERT(!mLogger, "Forgot to clear a previous listener?");
+
+  if (aManualListener) {
+    aManualListener->AsLogger(getter_AddRefs(mLogger));
+  }
+
+  aManualListener = nullptr;
+  if (!mLogger && mParams.LogThisCC(isShutdown)) {
+    mLogger = new nsCycleCollectorLogger();
+    if (mParams.AllTracesThisCC(isShutdown)) {
+      mLogger->SetAllTraces();
+    }
+  }
+
+  // On a WantAllTraces CC, force a synchronous global GC to prevent
+  // hijinks from ForgetSkippable and compartmental GCs.
+  bool forceGC = isShutdown || (mLogger && mLogger->IsAllTraces());
+
+  // BeginCycleCollectionCallback() might have started an IGC, and we need
+  // to finish it before we run FixGrayBits.
+  FinishAnyIncrementalGCInProgress();
+  timeLog.Checkpoint("Pre-FixGrayBits finish IGC");
+
+  FixGrayBits(forceGC, timeLog);
+
+  FreeSnowWhite(true);
+  timeLog.Checkpoint("BeginCollection FreeSnowWhite");
+
+  if (mLogger && NS_FAILED(mLogger->Begin())) {
+    mLogger = nullptr;
+  }
+
+  // FreeSnowWhite could potentially have started an IGC, which we need
+  // to finish before we look at any JS roots.
+  FinishAnyIncrementalGCInProgress();
+  timeLog.Checkpoint("Post-FreeSnowWhite finish IGC");
+
+  // Set up the data structures for building the graph.
+  JS::AutoAssertNoGC nogc;
+  JS::AutoEnterCycleCollection autocc(mJSContext->Context());
+  mGraph.Init();
+  mResults.Init();
+  mResults.mAnyManual = (aCCType != SliceCC);
+  bool mergeZones = ShouldMergeZones(aCCType);
+  mResults.mMergedZones = mergeZones;
+
+  MOZ_ASSERT(!mBuilder, "Forgot to clear mBuilder");
+  mBuilder = new CCGraphBuilder(mGraph, mResults, mJSContext, mLogger,
+                                mergeZones);
+  timeLog.Checkpoint("BeginCollection prepare graph builder");
+
+  if (mJSContext) {
+    mJSContext->TraverseRoots(*mBuilder);
+    timeLog.Checkpoint("mJSContext->TraverseRoots()");
+  }
+
+  AutoRestore<bool> ar(mScanInProgress);
+  MOZ_RELEASE_ASSERT(!mScanInProgress);
+  mScanInProgress = true;
+  mPurpleBuf.SelectPointers(*mBuilder);
+  timeLog.Checkpoint("SelectPointers()");
+
+  mBuilder->DoneAddingRoots();
+  mIncrementalPhase = GraphBuildingPhase;
+}
+
+uint32_t
+nsCycleCollector::SuspectedCount()
+{
+  CheckThreadSafety();
+  return mPurpleBuf.Count();
+}
+
+void
+nsCycleCollector::Shutdown(bool aDoCollect)
+{
+  CheckThreadSafety();
+
+  // Always delete snow white objects.
+  FreeSnowWhite(true);
+
+  if (aDoCollect) {
+    ShutdownCollect();
+  }
+}
+
+void
+nsCycleCollector::RemoveObjectFromGraph(void* aObj)
+{
+  if (IsIdle()) {
+    return;
+  }
+
+  mGraph.RemoveObjectFromMap(aObj);
+}
+
+void
+nsCycleCollector::SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf,
+                                      size_t* aObjectSize,
+                                      size_t* aGraphSize,
+                                      size_t* aPurpleBufferSize) const
+{
+  *aObjectSize = aMallocSizeOf(this);
+
+  *aGraphSize = mGraph.SizeOfExcludingThis(aMallocSizeOf);
+
+  *aPurpleBufferSize = mPurpleBuf.SizeOfExcludingThis(aMallocSizeOf);
+
+  // These fields are deliberately not measured:
+  // - mJSContext: because it's non-owning and measured by JS reporters.
+  // - mParams: because it only contains scalars.
+}
+
+JSPurpleBuffer*
+nsCycleCollector::GetJSPurpleBuffer()
+{
+  if (!mJSPurpleBuffer) {
+    // The Release call here confuses the GC analysis.
+    JS::AutoSuppressGCAnalysis nogc;
+    // JSPurpleBuffer keeps itself alive, but we need to create it in such way
+    // that it ends up in the normal purple buffer. That happens when
+    // nsRefPtr goes out of the scope and calls Release.
+    RefPtr<JSPurpleBuffer> pb = new JSPurpleBuffer(mJSPurpleBuffer);
+  }
+  return mJSPurpleBuffer;
+}
+
+////////////////////////////////////////////////////////////////////////
+// Module public API (exported in nsCycleCollector.h)
+// Just functions that redirect into the singleton, once it's built.
+////////////////////////////////////////////////////////////////////////
+
+void
+nsCycleCollector_registerJSContext(CycleCollectedJSContext* aCx)
+{
+  CollectorData* data = sCollectorData.get();
+
+  // We should have started the cycle collector by now.
+  MOZ_ASSERT(data);
+  MOZ_ASSERT(data->mCollector);
+  // But we shouldn't already have a context.
+  MOZ_ASSERT(!data->mContext);
+
+  data->mContext = aCx;
+  data->mCollector->RegisterJSContext(aCx);
+}
+
+void
+nsCycleCollector_forgetJSContext()
+{
+  CollectorData* data = sCollectorData.get();
+
+  // We should have started the cycle collector by now.
+  MOZ_ASSERT(data);
+  // And we shouldn't have already forgotten our context.
+  MOZ_ASSERT(data->mContext);
+
+  // But it may have shutdown already.
+  if (data->mCollector) {
+    data->mCollector->ForgetJSContext();
+    data->mContext = nullptr;
+  } else {
+    data->mContext = nullptr;
+    delete data;
+    sCollectorData.set(nullptr);
+  }
+}
+
+/* static */ CycleCollectedJSContext*
+CycleCollectedJSContext::Get()
+{
+  CollectorData* data = sCollectorData.get();
+  if (data) {
+    return data->mContext;
+  }
+  return nullptr;
+}
+
+MOZ_NEVER_INLINE static void
+SuspectAfterShutdown(void* aPtr, nsCycleCollectionParticipant* aCp,
+                     nsCycleCollectingAutoRefCnt* aRefCnt,
+                     bool* aShouldDelete)
+{
+  if (aRefCnt->get() == 0) {
+    if (!aShouldDelete) {
+      // The CC is shut down, so we can't be in the middle of an ICC.
+      CanonicalizeParticipant(&aPtr, &aCp);
+      aRefCnt->stabilizeForDeletion();
+      aCp->DeleteCycleCollectable(aPtr);
+    } else {
+      *aShouldDelete = true;
+    }
+  } else {
+    // Make sure we'll get called again.
+    aRefCnt->RemoveFromPurpleBuffer();
+  }
+}
+
+void
+NS_CycleCollectorSuspect3(void* aPtr, nsCycleCollectionParticipant* aCp,
+                          nsCycleCollectingAutoRefCnt* aRefCnt,
+                          bool* aShouldDelete)
+{
+  CollectorData* data = sCollectorData.get();
+
+  // We should have started the cycle collector by now.
+  MOZ_ASSERT(data);
+
+  if (MOZ_LIKELY(data->mCollector)) {
+    data->mCollector->Suspect(aPtr, aCp, aRefCnt);
+    return;
+  }
+  SuspectAfterShutdown(aPtr, aCp, aRefCnt, aShouldDelete);
+}
+
+uint32_t
+nsCycleCollector_suspectedCount()
+{
+  CollectorData* data = sCollectorData.get();
+
+  // We should have started the cycle collector by now.
+  MOZ_ASSERT(data);
+
+  if (!data->mCollector) {
+    return 0;
+  }
+
+  return data->mCollector->SuspectedCount();
+}
+
+bool
+nsCycleCollector_init()
+{
+#ifdef DEBUG
+  static bool sInitialized;
+
+  MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
+  MOZ_ASSERT(!sInitialized, "Called twice!?");
+  sInitialized = true;
+#endif
+
+  return sCollectorData.init();
+}
+
+void
+nsCycleCollector_startup()
+{
+  if (sCollectorData.get()) {
+    MOZ_CRASH();
+  }
+
+  CollectorData* data = new CollectorData;
+  data->mCollector = new nsCycleCollector();
+  data->mContext = nullptr;
+
+  sCollectorData.set(data);
+}
+
+void
+nsCycleCollector_setBeforeUnlinkCallback(CC_BeforeUnlinkCallback aCB)
+{
+  CollectorData* data = sCollectorData.get();
+
+  // We should have started the cycle collector by now.
+  MOZ_ASSERT(data);
+  MOZ_ASSERT(data->mCollector);
+
+  data->mCollector->SetBeforeUnlinkCallback(aCB);
+}
+
+void
+nsCycleCollector_setForgetSkippableCallback(CC_ForgetSkippableCallback aCB)
+{
+  CollectorData* data = sCollectorData.get();
+
+  // We should have started the cycle collector by now.
+  MOZ_ASSERT(data);
+  MOZ_ASSERT(data->mCollector);
+
+  data->mCollector->SetForgetSkippableCallback(aCB);
+}
+
+void
+nsCycleCollector_forgetSkippable(bool aRemoveChildlessNodes,
+                                 bool aAsyncSnowWhiteFreeing)
+{
+  CollectorData* data = sCollectorData.get();
+
+  // We should have started the cycle collector by now.
+  MOZ_ASSERT(data);
+  MOZ_ASSERT(data->mCollector);
+
+  PROFILER_LABEL("nsCycleCollector", "forgetSkippable",
+                 js::ProfileEntry::Category::CC);
+
+  TimeLog timeLog;
+  data->mCollector->ForgetSkippable(aRemoveChildlessNodes,
+                                    aAsyncSnowWhiteFreeing);
+  timeLog.Checkpoint("ForgetSkippable()");
+}
+
+void
+nsCycleCollector_dispatchDeferredDeletion(bool aContinuation, bool aPurge)
+{
+  CycleCollectedJSContext* cx = CycleCollectedJSContext::Get();
+  if (cx) {
+    cx->DispatchDeferredDeletion(aContinuation, aPurge);
+  }
+}
+
+bool
+nsCycleCollector_doDeferredDeletion()
+{
+  CollectorData* data = sCollectorData.get();
+
+  // We should have started the cycle collector by now.
+  MOZ_ASSERT(data);
+  MOZ_ASSERT(data->mCollector);
+  MOZ_ASSERT(data->mContext);
+
+  return data->mCollector->FreeSnowWhite(false);
+}
+
+already_AddRefed<nsICycleCollectorLogSink>
+nsCycleCollector_createLogSink()
+{
+  nsCOMPtr<nsICycleCollectorLogSink> sink = new nsCycleCollectorLogSinkToFile();
+  return sink.forget();
+}
+
+void
+nsCycleCollector_collect(nsICycleCollectorListener* aManualListener)
+{
+  CollectorData* data = sCollectorData.get();
+
+  // We should have started the cycle collector by now.
+  MOZ_ASSERT(data);
+  MOZ_ASSERT(data->mCollector);
+
+  PROFILER_LABEL("nsCycleCollector", "collect",
+                 js::ProfileEntry::Category::CC);
+
+  SliceBudget unlimitedBudget = SliceBudget::unlimited();
+  data->mCollector->Collect(ManualCC, unlimitedBudget, aManualListener);
+}
+
+void
+nsCycleCollector_collectSlice(SliceBudget& budget,
+                              bool aPreferShorterSlices)
+{
+  CollectorData* data = sCollectorData.get();
+
+  // We should have started the cycle collector by now.
+  MOZ_ASSERT(data);
+  MOZ_ASSERT(data->mCollector);
+
+  PROFILER_LABEL("nsCycleCollector", "collectSlice",
+                 js::ProfileEntry::Category::CC);
+
+  data->mCollector->Collect(SliceCC, budget, nullptr, aPreferShorterSlices);
+}
+
+void
+nsCycleCollector_prepareForGarbageCollection()
+{
+  CollectorData* data = sCollectorData.get();
+
+  MOZ_ASSERT(data);
+
+  if (!data->mCollector) {
+    return;
+  }
+
+  data->mCollector->PrepareForGarbageCollection();
+}
+
+void
+nsCycleCollector_finishAnyCurrentCollection()
+{
+  CollectorData* data = sCollectorData.get();
+
+  MOZ_ASSERT(data);
+
+  if (!data->mCollector) {
+    return;
+  }
+
+  data->mCollector->FinishAnyCurrentCollection();
+}
+
+void
+nsCycleCollector_shutdown(bool aDoCollect)
+{
+  CollectorData* data = sCollectorData.get();
+
+  if (data) {
+    MOZ_ASSERT(data->mCollector);
+    PROFILER_LABEL("nsCycleCollector", "shutdown",
+                   js::ProfileEntry::Category::CC);
+
+    data->mCollector->Shutdown(aDoCollect);
+    data->mCollector = nullptr;
+    if (data->mContext) {
+      // Run any remaining tasks that may have been enqueued via
+      // RunInStableState during the final cycle collection.
+      data->mContext->ProcessStableStateQueue();
+    }
+    if (!data->mContext) {
+      delete data;
+      sCollectorData.set(nullptr);
+    }
+  }
+}
diff --git a/xpcom/base/nsCycleCollector.h b/xpcom/base/nsCycleCollector.h
new file mode 100644
index 000000000..cd3fff406
--- /dev/null
+++ b/xpcom/base/nsCycleCollector.h
@@ -0,0 +1,72 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCycleCollector_h__
+#define nsCycleCollector_h__
+
+class nsICycleCollectorListener;
+class nsICycleCollectorLogSink;
+class nsISupports;
+template<class T> struct already_AddRefed;
+
+#include "nsError.h"
+#include "nsID.h"
+
+#include "js/SliceBudget.h"
+
+namespace mozilla {
+class CycleCollectedJSContext;
+} // namespace mozilla
+
+bool nsCycleCollector_init();
+
+void nsCycleCollector_startup();
+
+typedef void (*CC_BeforeUnlinkCallback)(void);
+void nsCycleCollector_setBeforeUnlinkCallback(CC_BeforeUnlinkCallback aCB);
+
+typedef void (*CC_ForgetSkippableCallback)(void);
+void nsCycleCollector_setForgetSkippableCallback(CC_ForgetSkippableCallback aCB);
+
+void nsCycleCollector_forgetSkippable(bool aRemoveChildlessNodes = false,
+                                      bool aAsyncSnowWhiteFreeing = false);
+
+void nsCycleCollector_prepareForGarbageCollection();
+
+// If an incremental cycle collection is in progress, finish it.
+void nsCycleCollector_finishAnyCurrentCollection();
+
+void nsCycleCollector_dispatchDeferredDeletion(bool aContinuation = false,
+                                               bool aPurge = false);
+bool nsCycleCollector_doDeferredDeletion();
+
+already_AddRefed<nsICycleCollectorLogSink> nsCycleCollector_createLogSink();
+
+void nsCycleCollector_collect(nsICycleCollectorListener* aManualListener);
+
+void nsCycleCollector_collectSlice(js::SliceBudget& budget,
+                                   bool aPreferShorterSlices = false);
+
+uint32_t nsCycleCollector_suspectedCount();
+
+// If aDoCollect is true, then run the GC and CC a few times before
+// shutting down the CC completely.
+void nsCycleCollector_shutdown(bool aDoCollect = true);
+
+// Helpers for interacting with JS
+void nsCycleCollector_registerJSContext(mozilla::CycleCollectedJSContext* aCx);
+void nsCycleCollector_forgetJSContext();
+
+#define NS_CYCLE_COLLECTOR_LOGGER_CID \
+{ 0x58be81b4, 0x39d2, 0x437c, \
+{ 0x94, 0xea, 0xae, 0xde, 0x2c, 0x62, 0x08, 0xd3 } }
+
+extern nsresult
+nsCycleCollectorLoggerConstructor(nsISupports* aOuter,
+                                  const nsIID& aIID,
+                                  void** aInstancePtr);
+
+#endif // nsCycleCollector_h__
diff --git a/xpcom/base/nsCycleCollectorTraceJSHelpers.cpp b/xpcom/base/nsCycleCollectorTraceJSHelpers.cpp
new file mode 100644
index 000000000..eb06a389c
--- /dev/null
+++ b/xpcom/base/nsCycleCollectorTraceJSHelpers.cpp
@@ -0,0 +1,105 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCycleCollectionParticipant.h"
+#include "jsapi.h"
+#include "jsfriendapi.h"
+
+void
+CycleCollectionNoteEdgeNameImpl(nsCycleCollectionTraversalCallback& aCallback,
+                                const char* aName,
+                                uint32_t aFlags)
+{
+  nsAutoCString arrayEdgeName(aName);
+  if (aFlags & CycleCollectionEdgeNameArrayFlag) {
+    arrayEdgeName.AppendLiteral("[i]");
+  }
+  aCallback.NoteNextEdgeName(arrayEdgeName.get());
+}
+
+void
+nsScriptObjectTracer::NoteJSChild(JS::GCCellPtr aGCThing, const char* aName,
+                                  void* aClosure)
+{
+  nsCycleCollectionTraversalCallback* cb =
+    static_cast<nsCycleCollectionTraversalCallback*>(aClosure);
+  NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(*cb, aName);
+  if (mozilla::AddToCCKind(aGCThing.kind())) {
+    cb->NoteJSChild(aGCThing);
+  }
+}
+
+void
+TraceCallbackFunc::Trace(JS::Heap<JS::Value>* aPtr, const char* aName,
+                         void* aClosure) const
+{
+  if (aPtr->unbarrieredGet().isMarkable()) {
+    mCallback(JS::GCCellPtr(aPtr->unbarrieredGet()), aName, aClosure);
+  }
+}
+
+void
+TraceCallbackFunc::Trace(JS::Heap<jsid>* aPtr, const char* aName,
+                         void* aClosure) const
+{
+  if (JSID_IS_GCTHING(aPtr->unbarrieredGet())) {
+    mCallback(JSID_TO_GCTHING(aPtr->unbarrieredGet()), aName, aClosure);
+  }
+}
+
+void
+TraceCallbackFunc::Trace(JS::Heap<JSObject*>* aPtr, const char* aName,
+                         void* aClosure) const
+{
+  if (*aPtr) {
+    mCallback(JS::GCCellPtr(aPtr->unbarrieredGet()), aName, aClosure);
+  }
+}
+
+void
+TraceCallbackFunc::Trace(JSObject** aPtr, const char* aName,
+                         void* aClosure) const
+{
+  if (*aPtr) {
+    mCallback(JS::GCCellPtr(*aPtr), aName, aClosure);
+  }
+}
+
+void
+TraceCallbackFunc::Trace(JS::TenuredHeap<JSObject*>* aPtr, const char* aName,
+                         void* aClosure) const
+{
+  if (*aPtr) {
+    mCallback(JS::GCCellPtr(aPtr->unbarrieredGetPtr()), aName, aClosure);
+  }
+}
+
+void
+TraceCallbackFunc::Trace(JS::Heap<JSFunction*>* aPtr, const char* aName,
+                         void* aClosure) const
+{
+  if (*aPtr) {
+    mCallback(JS::GCCellPtr(aPtr->unbarrieredGet()), aName, aClosure);
+  }
+}
+
+void
+TraceCallbackFunc::Trace(JS::Heap<JSString*>* aPtr, const char* aName,
+                         void* aClosure) const
+{
+  if (*aPtr) {
+    mCallback(JS::GCCellPtr(aPtr->unbarrieredGet()), aName, aClosure);
+  }
+}
+
+void
+TraceCallbackFunc::Trace(JS::Heap<JSScript*>* aPtr, const char* aName,
+                         void* aClosure) const
+{
+  if (*aPtr) {
+    mCallback(JS::GCCellPtr(aPtr->unbarrieredGet()), aName, aClosure);
+  }
+}
diff --git a/xpcom/base/nsDebugImpl.cpp b/xpcom/base/nsDebugImpl.cpp
new file mode 100644
index 000000000..36288d203
--- /dev/null
+++ b/xpcom/base/nsDebugImpl.cpp
@@ -0,0 +1,607 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Chromium headers must come before Mozilla headers.
+#include "base/process_util.h"
+
+#include "mozilla/Atomics.h"
+
+#include "nsDebugImpl.h"
+#include "nsDebug.h"
+#ifdef MOZ_CRASHREPORTER
+# include "nsExceptionHandler.h"
+#endif
+#include "nsString.h"
+#include "nsXULAppAPI.h"
+#include "prprf.h"
+#include "nsError.h"
+#include "prerror.h"
+#include "prerr.h"
+#include "prenv.h"
+
+#ifdef ANDROID
+#include <android/log.h>
+#endif
+
+#ifdef _WIN32
+/* for getenv() */
+#include <stdlib.h>
+#endif
+
+#include "nsTraceRefcnt.h"
+
+#if defined(XP_UNIX)
+#include <signal.h>
+#endif
+
+#if defined(XP_WIN)
+#include <tchar.h>
+#include "nsString.h"
+#endif
+
+#if defined(XP_MACOSX) || defined(__DragonFly__) || defined(__FreeBSD__) \
+ || defined(__NetBSD__) || defined(__OpenBSD__)
+#include <stdbool.h>
+#include <unistd.h>
+#include <sys/param.h>
+#include <sys/sysctl.h>
+#endif
+
+#if defined(__OpenBSD__)
+#include <sys/proc.h>
+#endif
+
+#if defined(__DragonFly__) || defined(__FreeBSD__)
+#include <sys/user.h>
+#endif
+
+#if defined(__NetBSD__)
+#undef KERN_PROC
+#define KERN_PROC KERN_PROC2
+#define KINFO_PROC struct kinfo_proc2
+#else
+#define KINFO_PROC struct kinfo_proc
+#endif
+
+#if defined(XP_MACOSX)
+#define KP_FLAGS kp_proc.p_flag
+#elif defined(__DragonFly__)
+#define KP_FLAGS kp_flags
+#elif defined(__FreeBSD__)
+#define KP_FLAGS ki_flag
+#elif defined(__OpenBSD__) && !defined(_P_TRACED)
+#define KP_FLAGS p_psflags
+#define P_TRACED PS_TRACED
+#else
+#define KP_FLAGS p_flag
+#endif
+
+#include "mozilla/mozalloc_abort.h"
+
+static void
+Abort(const char* aMsg);
+
+static void
+RealBreak();
+
+static void
+Break(const char* aMsg);
+
+#if defined(_WIN32)
+#include <windows.h>
+#include <signal.h>
+#include <malloc.h> // for _alloca
+#elif defined(XP_UNIX)
+#include <stdlib.h>
+#endif
+
+using namespace mozilla;
+
+static const char* sMultiprocessDescription = nullptr;
+
+static Atomic<int32_t> gAssertionCount;
+
+NS_IMPL_QUERY_INTERFACE(nsDebugImpl, nsIDebug2)
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsDebugImpl::AddRef()
+{
+  return 2;
+}
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsDebugImpl::Release()
+{
+  return 1;
+}
+
+NS_IMETHODIMP
+nsDebugImpl::Assertion(const char* aStr, const char* aExpr,
+                       const char* aFile, int32_t aLine)
+{
+  NS_DebugBreak(NS_DEBUG_ASSERTION, aStr, aExpr, aFile, aLine);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDebugImpl::Warning(const char* aStr, const char* aFile, int32_t aLine)
+{
+  NS_DebugBreak(NS_DEBUG_WARNING, aStr, nullptr, aFile, aLine);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDebugImpl::Break(const char* aFile, int32_t aLine)
+{
+  NS_DebugBreak(NS_DEBUG_BREAK, nullptr, nullptr, aFile, aLine);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDebugImpl::Abort(const char* aFile, int32_t aLine)
+{
+  NS_DebugBreak(NS_DEBUG_ABORT, nullptr, nullptr, aFile, aLine);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDebugImpl::GetIsDebugBuild(bool* aResult)
+{
+#ifdef DEBUG
+  *aResult = true;
+#else
+  *aResult = false;
+#endif
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDebugImpl::GetAssertionCount(int32_t* aResult)
+{
+  *aResult = gAssertionCount;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDebugImpl::GetIsDebuggerAttached(bool* aResult)
+{
+  *aResult = false;
+
+#if defined(XP_WIN)
+  *aResult = ::IsDebuggerPresent();
+#elif defined(XP_MACOSX) || defined(__DragonFly__) || defined(__FreeBSD__) \
+   || defined(__NetBSD__) || defined(__OpenBSD__)
+  // Specify the info we're looking for
+  int mib[] = {
+    CTL_KERN,
+    KERN_PROC,
+    KERN_PROC_PID,
+    getpid(),
+#if defined(__NetBSD__) || defined(__OpenBSD__)
+    sizeof(KINFO_PROC),
+    1,
+#endif
+  };
+  u_int mibSize = sizeof(mib) / sizeof(int);
+
+  KINFO_PROC info;
+  size_t infoSize = sizeof(info);
+  memset(&info, 0, infoSize);
+
+  if (sysctl(mib, mibSize, &info, &infoSize, nullptr, 0)) {
+    // if the call fails, default to false
+    *aResult = false;
+    return NS_OK;
+  }
+
+  if (info.KP_FLAGS & P_TRACED) {
+    *aResult = true;
+  }
+#endif
+
+  return NS_OK;
+}
+
+/* static */ void
+nsDebugImpl::SetMultiprocessMode(const char* aDesc)
+{
+  sMultiprocessDescription = aDesc;
+}
+
+/**
+ * Implementation of the nsDebug methods. Note that this code is
+ * always compiled in, in case some other module that uses it is
+ * compiled with debugging even if this library is not.
+ */
+enum nsAssertBehavior
+{
+  NS_ASSERT_UNINITIALIZED,
+  NS_ASSERT_WARN,
+  NS_ASSERT_SUSPEND,
+  NS_ASSERT_STACK,
+  NS_ASSERT_TRAP,
+  NS_ASSERT_ABORT,
+  NS_ASSERT_STACK_AND_ABORT
+};
+
+static nsAssertBehavior
+GetAssertBehavior()
+{
+  static nsAssertBehavior gAssertBehavior = NS_ASSERT_UNINITIALIZED;
+  if (gAssertBehavior != NS_ASSERT_UNINITIALIZED) {
+    return gAssertBehavior;
+  }
+
+  gAssertBehavior = NS_ASSERT_WARN;
+
+  const char* assertString = PR_GetEnv("XPCOM_DEBUG_BREAK");
+  if (!assertString || !*assertString) {
+    return gAssertBehavior;
+  }
+  if (!strcmp(assertString, "warn")) {
+    return gAssertBehavior = NS_ASSERT_WARN;
+  }
+  if (!strcmp(assertString, "suspend")) {
+    return gAssertBehavior = NS_ASSERT_SUSPEND;
+  }
+  if (!strcmp(assertString, "stack")) {
+    return gAssertBehavior = NS_ASSERT_STACK;
+  }
+  if (!strcmp(assertString, "abort")) {
+    return gAssertBehavior = NS_ASSERT_ABORT;
+  }
+  if (!strcmp(assertString, "trap") || !strcmp(assertString, "break")) {
+    return gAssertBehavior = NS_ASSERT_TRAP;
+  }
+  if (!strcmp(assertString, "stack-and-abort")) {
+    return gAssertBehavior = NS_ASSERT_STACK_AND_ABORT;
+  }
+
+  fprintf(stderr, "Unrecognized value of XPCOM_DEBUG_BREAK\n");
+  return gAssertBehavior;
+}
+
+struct FixedBuffer
+{
+  FixedBuffer() : curlen(0)
+  {
+    buffer[0] = '\0';
+  }
+
+  char buffer[500];
+  uint32_t curlen;
+};
+
+static int
+StuffFixedBuffer(void* aClosure, const char* aBuf, uint32_t aLen)
+{
+  if (!aLen) {
+    return 0;
+  }
+
+  FixedBuffer* fb = (FixedBuffer*)aClosure;
+
+  // strip the trailing null, we add it again later
+  if (aBuf[aLen - 1] == '\0') {
+    --aLen;
+  }
+
+  if (fb->curlen + aLen >= sizeof(fb->buffer)) {
+    aLen = sizeof(fb->buffer) - fb->curlen - 1;
+  }
+
+  if (aLen) {
+    memcpy(fb->buffer + fb->curlen, aBuf, aLen);
+    fb->curlen += aLen;
+    fb->buffer[fb->curlen] = '\0';
+  }
+
+  return aLen;
+}
+
+EXPORT_XPCOM_API(void)
+NS_DebugBreak(uint32_t aSeverity, const char* aStr, const char* aExpr,
+              const char* aFile, int32_t aLine)
+{
+  FixedBuffer nonPIDBuf;
+  FixedBuffer buf;
+  const char* sevString = "WARNING";
+
+  switch (aSeverity) {
+    case NS_DEBUG_ASSERTION:
+      sevString = "###!!! ASSERTION";
+      break;
+
+    case NS_DEBUG_BREAK:
+      sevString = "###!!! BREAK";
+      break;
+
+    case NS_DEBUG_ABORT:
+      sevString = "###!!! ABORT";
+      break;
+
+    default:
+      aSeverity = NS_DEBUG_WARNING;
+  }
+
+#define PRINT_TO_NONPID_BUFFER(...) PR_sxprintf(StuffFixedBuffer, &nonPIDBuf, __VA_ARGS__)
+  PRINT_TO_NONPID_BUFFER("%s: ", sevString);
+  if (aStr) {
+    PRINT_TO_NONPID_BUFFER("%s: ", aStr);
+  }
+  if (aExpr) {
+    PRINT_TO_NONPID_BUFFER("'%s', ", aExpr);
+  }
+  if (aFile) {
+    PRINT_TO_NONPID_BUFFER("file %s, ", aFile);
+  }
+  if (aLine != -1) {
+    PRINT_TO_NONPID_BUFFER("line %d", aLine);
+  }
+#undef PRINT_TO_NONPID_BUFFER
+
+  // Print "[PID]" or "[Desc PID]" at the beginning of the message.
+#define PRINT_TO_BUFFER(...) PR_sxprintf(StuffFixedBuffer, &buf, __VA_ARGS__)
+  PRINT_TO_BUFFER("[");
+  if (sMultiprocessDescription) {
+    PRINT_TO_BUFFER("%s ", sMultiprocessDescription);
+  }
+  PRINT_TO_BUFFER("%d] %s", base::GetCurrentProcId(), nonPIDBuf.buffer);
+#undef PRINT_TO_BUFFER
+
+
+  // errors on platforms without a debugdlg ring a bell on stderr
+#if !defined(XP_WIN)
+  if (aSeverity != NS_DEBUG_WARNING) {
+    fprintf(stderr, "\07");
+  }
+#endif
+
+#ifdef ANDROID
+  __android_log_print(ANDROID_LOG_INFO, "Gecko", "%s", buf.buffer);
+#endif
+
+  // Write the message to stderr unless it's a warning and MOZ_IGNORE_WARNINGS
+  // is set.
+  if (!(PR_GetEnv("MOZ_IGNORE_WARNINGS") && aSeverity == NS_DEBUG_WARNING)) {
+    fprintf(stderr, "%s\n", buf.buffer);
+    fflush(stderr);
+  }
+
+  switch (aSeverity) {
+    case NS_DEBUG_WARNING:
+      return;
+
+    case NS_DEBUG_BREAK:
+      Break(buf.buffer);
+      return;
+
+    case NS_DEBUG_ABORT: {
+#if defined(MOZ_CRASHREPORTER)
+      // Updating crash annotations in the child causes us to do IPC. This can
+      // really cause trouble if we're asserting from within IPC code. So we
+      // have to do without the annotations in that case.
+      if (XRE_IsParentProcess()) {
+        // Don't include the PID in the crash report annotation to
+        // allow faceting on crash-stats.mozilla.org.
+        nsCString note("xpcom_runtime_abort(");
+        note += nonPIDBuf.buffer;
+        note += ")";
+        CrashReporter::AppendAppNotesToCrashReport(note);
+        CrashReporter::AnnotateCrashReport(NS_LITERAL_CSTRING("AbortMessage"),
+                                           nsDependentCString(nonPIDBuf.buffer));
+      }
+#endif  // MOZ_CRASHREPORTER
+
+#if defined(DEBUG) && defined(_WIN32)
+      RealBreak();
+#endif
+#if defined(DEBUG)
+      nsTraceRefcnt::WalkTheStack(stderr);
+#endif
+      Abort(buf.buffer);
+      return;
+    }
+  }
+
+  // Now we deal with assertions
+  gAssertionCount++;
+
+  switch (GetAssertBehavior()) {
+    case NS_ASSERT_WARN:
+      return;
+
+    case NS_ASSERT_SUSPEND:
+#ifdef XP_UNIX
+      fprintf(stderr, "Suspending process; attach with the debugger.\n");
+      kill(0, SIGSTOP);
+#else
+      Break(buf.buffer);
+#endif
+      return;
+
+    case NS_ASSERT_STACK:
+      nsTraceRefcnt::WalkTheStack(stderr);
+      return;
+
+    case NS_ASSERT_STACK_AND_ABORT:
+      nsTraceRefcnt::WalkTheStack(stderr);
+      // Fall through to abort
+      MOZ_FALLTHROUGH;
+
+    case NS_ASSERT_ABORT:
+      Abort(buf.buffer);
+      return;
+
+    case NS_ASSERT_TRAP:
+    case NS_ASSERT_UNINITIALIZED: // Default to "trap" behavior
+      Break(buf.buffer);
+      return;
+  }
+}
+
+static void
+Abort(const char* aMsg)
+{
+  mozalloc_abort(aMsg);
+}
+
+static void
+RealBreak()
+{
+#if defined(_WIN32)
+  ::DebugBreak();
+#elif defined(XP_MACOSX)
+  raise(SIGTRAP);
+#elif defined(__GNUC__) && (defined(__i386__) || defined(__i386) || defined(__x86_64__))
+  asm("int $3");
+#elif defined(__arm__)
+  asm(
+#ifdef __ARM_ARCH_4T__
+    /* ARMv4T doesn't support the BKPT instruction, so if the compiler target
+     * is ARMv4T, we want to ensure the assembler will understand that ARMv5T
+     * instruction, while keeping the resulting object tagged as ARMv4T.
+     */
+    ".arch armv5t\n"
+    ".object_arch armv4t\n"
+#endif
+    "BKPT #0");
+#elif defined(SOLARIS)
+#if defined(__i386__) || defined(__i386) || defined(__x86_64__)
+  asm("int $3");
+#else
+  raise(SIGTRAP);
+#endif
+#else
+#warning do not know how to break on this platform
+#endif
+}
+
+// Abort() calls this function, don't call it!
+static void
+Break(const char* aMsg)
+{
+#if defined(_WIN32)
+  static int ignoreDebugger;
+  if (!ignoreDebugger) {
+    const char* shouldIgnoreDebugger = getenv("XPCOM_DEBUG_DLG");
+    ignoreDebugger =
+      1 + (shouldIgnoreDebugger && !strcmp(shouldIgnoreDebugger, "1"));
+  }
+  if ((ignoreDebugger == 2) || !::IsDebuggerPresent()) {
+    DWORD code = IDRETRY;
+
+    /* Create the debug dialog out of process to avoid the crashes caused by
+     * Windows events leaking into our event loop from an in process dialog.
+     * We do this by launching windbgdlg.exe (built in xpcom/windbgdlg).
+     * See http://bugzilla.mozilla.org/show_bug.cgi?id=54792
+     */
+    PROCESS_INFORMATION pi;
+    STARTUPINFOW si;
+    wchar_t executable[MAX_PATH];
+    wchar_t* pName;
+
+    memset(&pi, 0, sizeof(pi));
+
+    memset(&si, 0, sizeof(si));
+    si.cb          = sizeof(si);
+    si.wShowWindow = SW_SHOW;
+
+    // 2nd arg of CreateProcess is in/out
+    wchar_t* msgCopy = (wchar_t*)_alloca((strlen(aMsg) + 1) * sizeof(wchar_t));
+    wcscpy(msgCopy, NS_ConvertUTF8toUTF16(aMsg).get());
+
+    if (GetModuleFileNameW(GetModuleHandleW(L"xpcom.dll"), executable, MAX_PATH) &&
+        (pName = wcsrchr(executable, '\\')) != nullptr &&
+        wcscpy(pName + 1, L"windbgdlg.exe") &&
+        CreateProcessW(executable, msgCopy, nullptr, nullptr,
+                       false, DETACHED_PROCESS | NORMAL_PRIORITY_CLASS,
+                       nullptr, nullptr, &si, &pi)) {
+      WaitForSingleObject(pi.hProcess, INFINITE);
+      GetExitCodeProcess(pi.hProcess, &code);
+      CloseHandle(pi.hProcess);
+      CloseHandle(pi.hThread);
+    }
+
+    switch (code) {
+      case IDABORT:
+        //This should exit us
+        raise(SIGABRT);
+        //If we are ignored exit this way..
+        _exit(3);
+
+      case IDIGNORE:
+        return;
+    }
+  }
+
+  RealBreak();
+#elif defined(XP_MACOSX)
+  /* Note that we put this Mac OS X test above the GNUC/x86 test because the
+   * GNUC/x86 test is also true on Intel Mac OS X and we want the PPC/x86
+   * impls to be the same.
+   */
+  RealBreak();
+#elif defined(__GNUC__) && (defined(__i386__) || defined(__i386) || defined(__x86_64__))
+  RealBreak();
+#elif defined(__arm__)
+  RealBreak();
+#elif defined(SOLARIS)
+  RealBreak();
+#else
+#warning do not know how to break on this platform
+#endif
+}
+
+nsresult
+nsDebugImpl::Create(nsISupports* aOuter, const nsIID& aIID, void** aInstancePtr)
+{
+  static const nsDebugImpl* sImpl;
+
+  if (NS_WARN_IF(aOuter)) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+
+  if (!sImpl) {
+    sImpl = new nsDebugImpl();
+  }
+
+  return const_cast<nsDebugImpl*>(sImpl)->QueryInterface(aIID, aInstancePtr);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+nsresult
+NS_ErrorAccordingToNSPR()
+{
+  PRErrorCode err = PR_GetError();
+  switch (err) {
+    case PR_OUT_OF_MEMORY_ERROR:         return NS_ERROR_OUT_OF_MEMORY;
+    case PR_WOULD_BLOCK_ERROR:           return NS_BASE_STREAM_WOULD_BLOCK;
+    case PR_FILE_NOT_FOUND_ERROR:        return NS_ERROR_FILE_NOT_FOUND;
+    case PR_READ_ONLY_FILESYSTEM_ERROR:  return NS_ERROR_FILE_READ_ONLY;
+    case PR_NOT_DIRECTORY_ERROR:         return NS_ERROR_FILE_NOT_DIRECTORY;
+    case PR_IS_DIRECTORY_ERROR:          return NS_ERROR_FILE_IS_DIRECTORY;
+    case PR_LOOP_ERROR:                  return NS_ERROR_FILE_UNRESOLVABLE_SYMLINK;
+    case PR_FILE_EXISTS_ERROR:           return NS_ERROR_FILE_ALREADY_EXISTS;
+    case PR_FILE_IS_LOCKED_ERROR:        return NS_ERROR_FILE_IS_LOCKED;
+    case PR_FILE_TOO_BIG_ERROR:          return NS_ERROR_FILE_TOO_BIG;
+    case PR_NO_DEVICE_SPACE_ERROR:       return NS_ERROR_FILE_NO_DEVICE_SPACE;
+    case PR_NAME_TOO_LONG_ERROR:         return NS_ERROR_FILE_NAME_TOO_LONG;
+    case PR_DIRECTORY_NOT_EMPTY_ERROR:   return NS_ERROR_FILE_DIR_NOT_EMPTY;
+    case PR_NO_ACCESS_RIGHTS_ERROR:      return NS_ERROR_FILE_ACCESS_DENIED;
+    default:                             return NS_ERROR_FAILURE;
+  }
+}
+
+void
+NS_ABORT_OOM(size_t aSize)
+{
+#if defined(MOZ_CRASHREPORTER)
+  CrashReporter::AnnotateOOMAllocationSize(aSize);
+#endif
+  MOZ_CRASH("OOM");
+}
diff --git a/xpcom/base/nsDebugImpl.h b/xpcom/base/nsDebugImpl.h
new file mode 100644
index 000000000..23680238a
--- /dev/null
+++ b/xpcom/base/nsDebugImpl.h
@@ -0,0 +1,41 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsDebugImpl_h
+#define nsDebugImpl_h
+
+#include "nsIDebug2.h"
+
+class nsDebugImpl : public nsIDebug2
+{
+public:
+  nsDebugImpl() = default;
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIDEBUG2
+
+  static nsresult Create(nsISupports* aOuter, const nsIID& aIID,
+                         void** aInstancePtr);
+
+  /*
+   * Inform nsDebugImpl that we're in multiprocess mode.
+   *
+   * If aDesc is not nullptr, the string it points to must be
+   * statically-allocated (i.e., it must be a string literal).
+   */
+  static void SetMultiprocessMode(const char* aDesc);
+};
+
+
+#define NS_DEBUG_CONTRACTID "@mozilla.org/xpcom/debug;1"
+#define NS_DEBUG_CID                                 \
+{ /* cb6cdb94-e417-4601-b4a5-f991bf41453d */         \
+  0xcb6cdb94,                                        \
+    0xe417,                                          \
+    0x4601,                                          \
+    {0xb4, 0xa5, 0xf9, 0x91, 0xbf, 0x41, 0x45, 0x3d} \
+}
+
+#endif // nsDebugImpl_h
diff --git a/xpcom/base/nsDumpUtils.cpp b/xpcom/base/nsDumpUtils.cpp
new file mode 100644
index 000000000..c68862d08
--- /dev/null
+++ b/xpcom/base/nsDumpUtils.cpp
@@ -0,0 +1,513 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsDumpUtils.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsDirectoryServiceUtils.h"
+#include "prenv.h"
+#include <errno.h>
+#include "mozilla/Services.h"
+#include "nsIObserverService.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/Unused.h"
+
+#ifdef XP_UNIX // {
+#include "mozilla/Preferences.h"
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+using namespace mozilla;
+
+/*
+ * The following code supports triggering a registered callback upon
+ * receiving a specific signal.
+ *
+ * Take about:memory for example, we register
+ * 1. doGCCCDump for doMemoryReport
+ * 2. doMemoryReport for sDumpAboutMemorySignum(SIGRTMIN)
+ *                       and sDumpAboutMemoryAfterMMUSignum(SIGRTMIN+1).
+ *
+ * When we receive one of these signals, we write the signal number to a pipe.
+ * The IO thread then notices that the pipe has been written to, and kicks off
+ * the appropriate task on the main thread.
+ *
+ * This scheme is similar to using signalfd(), except it's portable and it
+ * doesn't require the use of sigprocmask, which is problematic because it
+ * masks signals received by child processes.
+ *
+ * In theory, we could use Chromium's MessageLoopForIO::CatchSignal() for this.
+ * But that uses libevent, which does not handle the realtime signals (bug
+ * 794074).
+ */
+
+// This is the write-end of a pipe that we use to notice when a
+// specific signal occurs.
+static Atomic<int> sDumpPipeWriteFd(-1);
+
+const char* const FifoWatcher::kPrefName =
+  "memory_info_dumper.watch_fifo.enabled";
+
+static void
+DumpSignalHandler(int aSignum)
+{
+  // This is a signal handler, so everything in here needs to be
+  // async-signal-safe.  Be careful!
+
+  if (sDumpPipeWriteFd != -1) {
+    uint8_t signum = static_cast<int>(aSignum);
+    Unused << write(sDumpPipeWriteFd, &signum, sizeof(signum));
+  }
+}
+
+NS_IMPL_ISUPPORTS(FdWatcher, nsIObserver);
+
+void
+FdWatcher::Init()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  nsCOMPtr<nsIObserverService> os = services::GetObserverService();
+  os->AddObserver(this, "xpcom-shutdown", /* ownsWeak = */ false);
+
+  XRE_GetIOMessageLoop()->PostTask(NewRunnableMethod(this, &FdWatcher::StartWatching));
+}
+
+// Implementations may call this function multiple times if they ensure that
+// it's safe to call OpenFd() multiple times and they call StopWatching()
+// first.
+void
+FdWatcher::StartWatching()
+{
+  MOZ_ASSERT(XRE_GetIOMessageLoop() == MessageLoopForIO::current());
+  MOZ_ASSERT(mFd == -1);
+
+  mFd = OpenFd();
+  if (mFd == -1) {
+    LOG("FdWatcher: OpenFd failed.");
+    return;
+  }
+
+  MessageLoopForIO::current()->WatchFileDescriptor(
+    mFd, /* persistent = */ true,
+    MessageLoopForIO::WATCH_READ,
+    &mReadWatcher, this);
+}
+
+// Since implementations can call StartWatching() multiple times, they can of
+// course call StopWatching() multiple times.
+void
+FdWatcher::StopWatching()
+{
+  MOZ_ASSERT(XRE_GetIOMessageLoop() == MessageLoopForIO::current());
+
+  mReadWatcher.StopWatchingFileDescriptor();
+  if (mFd != -1) {
+    close(mFd);
+    mFd = -1;
+  }
+}
+
+StaticRefPtr<SignalPipeWatcher> SignalPipeWatcher::sSingleton;
+
+/* static */ SignalPipeWatcher*
+SignalPipeWatcher::GetSingleton()
+{
+  if (!sSingleton) {
+    sSingleton = new SignalPipeWatcher();
+    sSingleton->Init();
+    ClearOnShutdown(&sSingleton);
+  }
+  return sSingleton;
+}
+
+void
+SignalPipeWatcher::RegisterCallback(uint8_t aSignal,
+                                    PipeCallback aCallback)
+{
+  MutexAutoLock lock(mSignalInfoLock);
+
+  for (SignalInfoArray::index_type i = 0; i < mSignalInfo.Length(); ++i) {
+    if (mSignalInfo[i].mSignal == aSignal) {
+      LOG("Register Signal(%d) callback failed! (DUPLICATE)", aSignal);
+      return;
+    }
+  }
+  SignalInfo signalInfo = { aSignal, aCallback };
+  mSignalInfo.AppendElement(signalInfo);
+  RegisterSignalHandler(signalInfo.mSignal);
+}
+
+void
+SignalPipeWatcher::RegisterSignalHandler(uint8_t aSignal)
+{
+  struct sigaction action;
+  memset(&action, 0, sizeof(action));
+  sigemptyset(&action.sa_mask);
+  action.sa_handler = DumpSignalHandler;
+
+  if (aSignal) {
+    if (sigaction(aSignal, &action, nullptr)) {
+      LOG("SignalPipeWatcher failed to register sig %d.", aSignal);
+    }
+  } else {
+    MutexAutoLock lock(mSignalInfoLock);
+    for (SignalInfoArray::index_type i = 0; i < mSignalInfo.Length(); i++) {
+      if (sigaction(mSignalInfo[i].mSignal, &action, nullptr)) {
+        LOG("SignalPipeWatcher failed to register signal(%d) "
+            "dump signal handler.", mSignalInfo[i].mSignal);
+      }
+    }
+  }
+}
+
+SignalPipeWatcher::~SignalPipeWatcher()
+{
+  if (sDumpPipeWriteFd != -1) {
+    StopWatching();
+  }
+}
+
+int
+SignalPipeWatcher::OpenFd()
+{
+  MOZ_ASSERT(XRE_GetIOMessageLoop() == MessageLoopForIO::current());
+
+  // Create a pipe.  When we receive a signal in our signal handler, we'll
+  // write the signum to the write-end of this pipe.
+  int pipeFds[2];
+  if (pipe(pipeFds)) {
+    LOG("SignalPipeWatcher failed to create pipe.");
+    return -1;
+  }
+
+  // Close this pipe on calls to exec().
+  fcntl(pipeFds[0], F_SETFD, FD_CLOEXEC);
+  fcntl(pipeFds[1], F_SETFD, FD_CLOEXEC);
+
+  int readFd = pipeFds[0];
+  sDumpPipeWriteFd = pipeFds[1];
+
+  RegisterSignalHandler();
+  return readFd;
+}
+
+void
+SignalPipeWatcher::StopWatching()
+{
+  MOZ_ASSERT(XRE_GetIOMessageLoop() == MessageLoopForIO::current());
+
+  // Close sDumpPipeWriteFd /after/ setting the fd to -1.
+  // Otherwise we have the (admittedly far-fetched) race where we
+  //
+  //  1) close sDumpPipeWriteFd
+  //  2) open a new fd with the same number as sDumpPipeWriteFd
+  //     had.
+  //  3) receive a signal, then write to the fd.
+  int pipeWriteFd = sDumpPipeWriteFd.exchange(-1);
+  close(pipeWriteFd);
+
+  FdWatcher::StopWatching();
+}
+
+void
+SignalPipeWatcher::OnFileCanReadWithoutBlocking(int aFd)
+{
+  MOZ_ASSERT(XRE_GetIOMessageLoop() == MessageLoopForIO::current());
+
+  uint8_t signum;
+  ssize_t numReceived = read(aFd, &signum, sizeof(signum));
+  if (numReceived != sizeof(signum)) {
+    LOG("Error reading from buffer in "
+        "SignalPipeWatcher::OnFileCanReadWithoutBlocking.");
+    return;
+  }
+
+  {
+    MutexAutoLock lock(mSignalInfoLock);
+    for (SignalInfoArray::index_type i = 0; i < mSignalInfo.Length(); i++) {
+      if (signum == mSignalInfo[i].mSignal) {
+        mSignalInfo[i].mCallback(signum);
+        return;
+      }
+    }
+  }
+  LOG("SignalPipeWatcher got unexpected signum.");
+}
+
+StaticRefPtr<FifoWatcher> FifoWatcher::sSingleton;
+
+/* static */ FifoWatcher*
+FifoWatcher::GetSingleton()
+{
+  if (!sSingleton) {
+    nsAutoCString dirPath;
+    Preferences::GetCString(
+      "memory_info_dumper.watch_fifo.directory", &dirPath);
+    sSingleton = new FifoWatcher(dirPath);
+    sSingleton->Init();
+    ClearOnShutdown(&sSingleton);
+  }
+  return sSingleton;
+}
+
+/* static */ bool
+FifoWatcher::MaybeCreate()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!XRE_IsParentProcess()) {
+    // We want this to be main-process only, since two processes can't listen
+    // to the same fifo.
+    return false;
+  }
+
+  if (!Preferences::GetBool(kPrefName, false)) {
+    LOG("Fifo watcher disabled via pref.");
+    return false;
+  }
+
+  // The FifoWatcher is held alive by the observer service.
+  if (!sSingleton) {
+    GetSingleton();
+  }
+  return true;
+}
+
+void
+FifoWatcher::RegisterCallback(const nsCString& aCommand, FifoCallback aCallback)
+{
+  MutexAutoLock lock(mFifoInfoLock);
+
+  for (FifoInfoArray::index_type i = 0; i < mFifoInfo.Length(); ++i) {
+    if (mFifoInfo[i].mCommand.Equals(aCommand)) {
+      LOG("Register command(%s) callback failed! (DUPLICATE)", aCommand.get());
+      return;
+    }
+  }
+  FifoInfo aFifoInfo = { aCommand, aCallback };
+  mFifoInfo.AppendElement(aFifoInfo);
+}
+
+FifoWatcher::~FifoWatcher()
+{
+}
+
+int
+FifoWatcher::OpenFd()
+{
+  // If the memory_info_dumper.directory pref is specified, put the fifo
+  // there.  Otherwise, put it into the system's tmp directory.
+
+  nsCOMPtr<nsIFile> file;
+
+  nsresult rv;
+  if (mDirPath.Length() > 0) {
+    rv = XRE_GetFileFromPath(mDirPath.get(), getter_AddRefs(file));
+    if (NS_FAILED(rv)) {
+      LOG("FifoWatcher failed to open file \"%s\"", mDirPath.get());
+      return -1;
+    }
+  } else {
+    rv = NS_GetSpecialDirectory(NS_OS_TEMP_DIR, getter_AddRefs(file));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return -1;
+    }
+  }
+
+  rv = file->AppendNative(NS_LITERAL_CSTRING("debug_info_trigger"));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return -1;
+  }
+
+  nsAutoCString path;
+  rv = file->GetNativePath(path);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return -1;
+  }
+
+  // unlink might fail because the file doesn't exist, or for other reasons.
+  // But we don't care it fails; any problems will be detected later, when we
+  // try to mkfifo or open the file.
+  if (unlink(path.get())) {
+    LOG("FifoWatcher::OpenFifo unlink failed; errno=%d.  "
+        "Continuing despite error.", errno);
+  }
+
+  if (mkfifo(path.get(), 0766)) {
+    LOG("FifoWatcher::OpenFifo mkfifo failed; errno=%d", errno);
+    return -1;
+  }
+
+#ifdef ANDROID
+  // Android runs with a umask, so we need to chmod our fifo to make it
+  // world-writable.
+  chmod(path.get(), 0666);
+#endif
+
+  int fd;
+  do {
+    // The fifo will block until someone else has written to it.  In
+    // particular, open() will block until someone else has opened it for
+    // writing!  We want open() to succeed and read() to block, so we open
+    // with NONBLOCK and then fcntl that away.
+    fd = open(path.get(), O_RDONLY | O_NONBLOCK);
+  } while (fd == -1 && errno == EINTR);
+
+  if (fd == -1) {
+    LOG("FifoWatcher::OpenFifo open failed; errno=%d", errno);
+    return -1;
+  }
+
+  // Make fd blocking now that we've opened it.
+  if (fcntl(fd, F_SETFL, 0)) {
+    close(fd);
+    return -1;
+  }
+
+  return fd;
+}
+
+void
+FifoWatcher::OnFileCanReadWithoutBlocking(int aFd)
+{
+  MOZ_ASSERT(XRE_GetIOMessageLoop() == MessageLoopForIO::current());
+
+  char buf[1024];
+  int nread;
+  do {
+    // sizeof(buf) - 1 to leave space for the null-terminator.
+    nread = read(aFd, buf, sizeof(buf));
+  } while (nread == -1 && errno == EINTR);
+
+  if (nread == -1) {
+    // We want to avoid getting into a situation where
+    // OnFileCanReadWithoutBlocking is called in an infinite loop, so when
+    // something goes wrong, stop watching the fifo altogether.
+    LOG("FifoWatcher hit an error (%d) and is quitting.", errno);
+    StopWatching();
+    return;
+  }
+
+  if (nread == 0) {
+    // If we get EOF, that means that the other side closed the fifo.  We need
+    // to close and re-open the fifo; if we don't,
+    // OnFileCanWriteWithoutBlocking will be called in an infinite loop.
+
+    LOG("FifoWatcher closing and re-opening fifo.");
+    StopWatching();
+    StartWatching();
+    return;
+  }
+
+  nsAutoCString inputStr;
+  inputStr.Append(buf, nread);
+
+  // Trimming whitespace is important because if you do
+  //   |echo "foo" >> debug_info_trigger|,
+  // it'll actually write "foo\n" to the fifo.
+  inputStr.Trim("\b\t\r\n");
+
+  {
+    MutexAutoLock lock(mFifoInfoLock);
+
+    for (FifoInfoArray::index_type i = 0; i < mFifoInfo.Length(); i++) {
+      const nsCString commandStr = mFifoInfo[i].mCommand;
+      if (inputStr == commandStr.get()) {
+        mFifoInfo[i].mCallback(inputStr);
+        return;
+      }
+    }
+  }
+  LOG("Got unexpected value from fifo; ignoring it.");
+}
+
+#endif // XP_UNIX }
+
+// In Android case, this function will open a file named aFilename under
+// /data/local/tmp/"aFoldername".
+// Otherwise, it will open a file named aFilename under "NS_OS_TEMP_DIR".
+/* static */ nsresult
+nsDumpUtils::OpenTempFile(const nsACString& aFilename, nsIFile** aFile,
+                          const nsACString& aFoldername, Mode aMode)
+{
+#ifdef ANDROID
+  // For Android, first try the downloads directory which is world-readable
+  // rather than the temp directory which is not.
+  if (!*aFile) {
+    char* env = PR_GetEnv("DOWNLOADS_DIRECTORY");
+    if (env) {
+      NS_NewNativeLocalFile(nsCString(env), /* followLinks = */ true, aFile);
+    }
+  }
+#endif
+  nsresult rv;
+  if (!*aFile) {
+    rv = NS_GetSpecialDirectory(NS_OS_TEMP_DIR, aFile);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+#ifdef ANDROID
+  // /data/local/tmp is a true tmp directory; anyone can create a file there,
+  // but only the user which created the file can remove it.  We want non-root
+  // users to be able to remove these files, so we write them into a
+  // subdirectory of the temp directory and chmod 777 that directory.
+  if (aFoldername != EmptyCString()) {
+    rv = (*aFile)->AppendNative(aFoldername);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    // It's OK if this fails; that probably just means that the directory
+    // already exists.
+    Unused << (*aFile)->Create(nsIFile::DIRECTORY_TYPE, 0777);
+
+    nsAutoCString dirPath;
+    rv = (*aFile)->GetNativePath(dirPath);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    while (chmod(dirPath.get(), 0777) == -1 && errno == EINTR) {
+    }
+  }
+#endif
+
+  nsCOMPtr<nsIFile> file(*aFile);
+
+  rv = file->AppendNative(aFilename);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  if (aMode == CREATE_UNIQUE) {
+    rv = file->CreateUnique(nsIFile::NORMAL_FILE_TYPE, 0666);
+  } else {
+    rv = file->Create(nsIFile::NORMAL_FILE_TYPE, 0666);
+  }
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+#ifdef ANDROID
+  // Make this file world-read/writable; the permissions passed to the
+  // CreateUnique call above are not sufficient on Android, which runs with a
+  // umask.
+  nsAutoCString path;
+  rv = file->GetNativePath(path);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  while (chmod(path.get(), 0666) == -1 && errno == EINTR) {
+  }
+#endif
+
+  return NS_OK;
+}
diff --git a/xpcom/base/nsDumpUtils.h b/xpcom/base/nsDumpUtils.h
new file mode 100644
index 000000000..12a99da18
--- /dev/null
+++ b/xpcom/base/nsDumpUtils.h
@@ -0,0 +1,203 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_nsDumpUtils_h
+#define mozilla_nsDumpUtils_h
+
+#include "nsIObserver.h"
+#include "base/message_loop.h"
+#include "nsXULAppAPI.h"
+#include "nsThreadUtils.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/StaticPtr.h"
+#include "nsTArray.h"
+
+#ifdef LOG
+#undef LOG
+#endif
+
+#ifdef ANDROID
+#include "android/log.h"
+#define LOG(...) __android_log_print(ANDROID_LOG_INFO, "Gecko:DumpUtils", ## __VA_ARGS__)
+#else
+#define LOG(...)
+#endif
+
+#ifdef XP_UNIX // {
+
+/**
+ * Abstract base class for something which watches an fd and takes action when
+ * we can read from it without blocking.
+ */
+class FdWatcher
+  : public MessageLoopForIO::Watcher
+  , public nsIObserver
+{
+protected:
+  MessageLoopForIO::FileDescriptorWatcher mReadWatcher;
+  int mFd;
+
+  virtual ~FdWatcher()
+  {
+    // StopWatching should have run.
+    MOZ_ASSERT(mFd == -1);
+  }
+
+public:
+  FdWatcher()
+    : mFd(-1)
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+  }
+
+  /**
+   * Open the fd to watch.  If we encounter an error, return -1.
+   */
+  virtual int OpenFd() = 0;
+
+  /**
+   * Called when you can read() from the fd without blocking.  Note that this
+   * function is also called when you're at eof (read() returns 0 in this case).
+   */
+  virtual void OnFileCanReadWithoutBlocking(int aFd) override = 0;
+  virtual void OnFileCanWriteWithoutBlocking(int aFd) override {};
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  /**
+   * Initialize this object.  This should be called right after the object is
+   * constructed.  (This would go in the constructor, except we interact with
+   * XPCOM, which we can't do from a constructor because our refcount is 0 at
+   * that point.)
+   */
+  void Init();
+
+  // Implementations may call this function multiple times if they ensure that
+
+  virtual void StartWatching();
+
+  // Since implementations can call StartWatching() multiple times, they can of
+  // course call StopWatching() multiple times.
+  virtual void StopWatching();
+
+  NS_IMETHOD Observe(nsISupports* aSubject, const char* aTopic,
+                     const char16_t* aData) override
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+    MOZ_ASSERT(!strcmp(aTopic, "xpcom-shutdown"));
+
+    XRE_GetIOMessageLoop()->PostTask(mozilla::NewRunnableMethod(this, &FdWatcher::StopWatching));
+
+    return NS_OK;
+  }
+};
+
+typedef void (*FifoCallback)(const nsCString& aInputStr);
+struct FifoInfo
+{
+  nsCString mCommand;
+  FifoCallback mCallback;
+};
+typedef nsTArray<FifoInfo> FifoInfoArray;
+
+class FifoWatcher : public FdWatcher
+{
+public:
+  /**
+   * The name of the preference used to enable/disable the FifoWatcher.
+   */
+  static const char* const kPrefName;
+
+  static FifoWatcher* GetSingleton();
+
+  static bool MaybeCreate();
+
+  void RegisterCallback(const nsCString& aCommand, FifoCallback aCallback);
+
+  virtual ~FifoWatcher();
+
+  virtual int OpenFd();
+
+  virtual void OnFileCanReadWithoutBlocking(int aFd);
+
+private:
+  nsAutoCString mDirPath;
+
+  static mozilla::StaticRefPtr<FifoWatcher> sSingleton;
+
+  explicit FifoWatcher(nsCString aPath)
+    : mDirPath(aPath)
+    , mFifoInfoLock("FifoWatcher.mFifoInfoLock")
+  {
+  }
+
+  mozilla::Mutex mFifoInfoLock; // protects mFifoInfo
+  FifoInfoArray mFifoInfo;
+};
+
+typedef void (*PipeCallback)(const uint8_t aRecvSig);
+struct SignalInfo
+{
+  uint8_t mSignal;
+  PipeCallback mCallback;
+};
+typedef nsTArray<SignalInfo> SignalInfoArray;
+
+class SignalPipeWatcher : public FdWatcher
+{
+public:
+  static SignalPipeWatcher* GetSingleton();
+
+  void RegisterCallback(uint8_t aSignal, PipeCallback aCallback);
+
+  void RegisterSignalHandler(uint8_t aSignal = 0);
+
+  virtual ~SignalPipeWatcher();
+
+  virtual int OpenFd();
+
+  virtual void StopWatching();
+
+  virtual void OnFileCanReadWithoutBlocking(int aFd);
+
+private:
+  static mozilla::StaticRefPtr<SignalPipeWatcher> sSingleton;
+
+  SignalPipeWatcher()
+    : mSignalInfoLock("SignalPipeWatcher.mSignalInfoLock")
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+  }
+
+  mozilla::Mutex mSignalInfoLock; // protects mSignalInfo
+  SignalInfoArray mSignalInfo;
+};
+
+#endif // XP_UNIX }
+
+class nsDumpUtils
+{
+public:
+
+  enum Mode {
+    CREATE,
+    CREATE_UNIQUE
+  };
+
+  /**
+   * This function creates a new unique file based on |aFilename| in a
+   * world-readable temp directory. This is the system temp directory
+   * or, in the case of Android, the downloads directory. If |aFile| is
+   * non-null, it is assumed to point to a folder, and that folder is used
+   * instead.
+   */
+  static nsresult OpenTempFile(const nsACString& aFilename,
+                               nsIFile** aFile,
+                               const nsACString& aFoldername = EmptyCString(),
+                               Mode aMode = CREATE_UNIQUE);
+};
+
+#endif
diff --git a/xpcom/base/nsError.h b/xpcom/base/nsError.h
new file mode 100644
index 000000000..b9e5d23f6
--- /dev/null
+++ b/xpcom/base/nsError.h
@@ -0,0 +1,219 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsError_h__
+#define nsError_h__
+
+#ifndef __cplusplus
+#error nsError.h no longer supports C sources
+#endif
+
+#include "mozilla/Attributes.h"
+#include "mozilla/Likely.h"
+
+#include <stdint.h>
+
+/*
+ * To add error code to your module, you need to do the following:
+ *
+ * 1) Add a module offset code.  Add yours to the bottom of the list
+ *    right below this comment, adding 1.
+ *
+ * 2) In your module, define a header file which uses one of the
+ *    NE_ERROR_GENERATExxxxxx macros.  Some examples below:
+ *
+ *    #define NS_ERROR_MYMODULE_MYERROR1 NS_ERROR_GENERATE(NS_ERROR_SEVERITY_ERROR,NS_ERROR_MODULE_MYMODULE,1)
+ *    #define NS_ERROR_MYMODULE_MYERROR2 NS_ERROR_GENERATE_SUCCESS(NS_ERROR_MODULE_MYMODULE,2)
+ *    #define NS_ERROR_MYMODULE_MYERROR3 NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_MYMODULE,3)
+ *
+ */
+
+
+/**
+ * @name Standard Module Offset Code. Each Module should identify a unique number
+ *       and then all errors associated with that module become offsets from the
+ *       base associated with that module id. There are 16 bits of code bits for
+ *       each module.
+ */
+
+#define NS_ERROR_MODULE_XPCOM      1
+#define NS_ERROR_MODULE_BASE       2
+#define NS_ERROR_MODULE_GFX        3
+#define NS_ERROR_MODULE_WIDGET     4
+#define NS_ERROR_MODULE_CALENDAR   5
+#define NS_ERROR_MODULE_NETWORK    6
+#define NS_ERROR_MODULE_PLUGINS    7
+#define NS_ERROR_MODULE_LAYOUT     8
+#define NS_ERROR_MODULE_HTMLPARSER 9
+#define NS_ERROR_MODULE_RDF        10
+#define NS_ERROR_MODULE_UCONV      11
+#define NS_ERROR_MODULE_REG        12
+#define NS_ERROR_MODULE_FILES      13
+#define NS_ERROR_MODULE_DOM        14
+#define NS_ERROR_MODULE_IMGLIB     15
+#define NS_ERROR_MODULE_MAILNEWS   16
+#define NS_ERROR_MODULE_EDITOR     17
+#define NS_ERROR_MODULE_XPCONNECT  18
+#define NS_ERROR_MODULE_PROFILE    19
+#define NS_ERROR_MODULE_LDAP       20
+#define NS_ERROR_MODULE_SECURITY   21
+#define NS_ERROR_MODULE_DOM_XPATH  22
+/* 23 used to be NS_ERROR_MODULE_DOM_RANGE (see bug 711047) */
+#define NS_ERROR_MODULE_URILOADER  24
+#define NS_ERROR_MODULE_CONTENT    25
+#define NS_ERROR_MODULE_PYXPCOM    26
+#define NS_ERROR_MODULE_XSLT       27
+#define NS_ERROR_MODULE_IPC        28
+#define NS_ERROR_MODULE_SVG        29
+#define NS_ERROR_MODULE_STORAGE    30
+#define NS_ERROR_MODULE_SCHEMA     31
+#define NS_ERROR_MODULE_DOM_FILE   32
+#define NS_ERROR_MODULE_DOM_INDEXEDDB 33
+#define NS_ERROR_MODULE_DOM_FILEHANDLE 34
+#define NS_ERROR_MODULE_SIGNED_JAR 35
+#define NS_ERROR_MODULE_DOM_FILESYSTEM 36
+#define NS_ERROR_MODULE_DOM_BLUETOOTH 37
+#define NS_ERROR_MODULE_SIGNED_APP 38
+#define NS_ERROR_MODULE_DOM_ANIM 39
+#define NS_ERROR_MODULE_DOM_PUSH 40
+#define NS_ERROR_MODULE_DOM_MEDIA 41
+
+/* NS_ERROR_MODULE_GENERAL should be used by modules that do not
+ * care if return code values overlap. Callers of methods that
+ * return such codes should be aware that they are not
+ * globally unique. Implementors should be careful about blindly
+ * returning codes from other modules that might also use
+ * the generic base.
+ */
+#define NS_ERROR_MODULE_GENERAL    51
+
+/**
+ * @name Severity Code.  This flag identifies the level of warning
+ */
+
+#define NS_ERROR_SEVERITY_SUCCESS       0
+#define NS_ERROR_SEVERITY_ERROR         1
+
+/**
+ * @name Mozilla Code.  This flag separates consumers of mozilla code
+ *       from the native platform
+ */
+
+#define NS_ERROR_MODULE_BASE_OFFSET 0x45
+
+/* Helpers for defining our enum, to be undef'd later */
+#define SUCCESS_OR_FAILURE(sev, module, code) \
+  ((uint32_t)(sev) << 31) | \
+  ((uint32_t)(module + NS_ERROR_MODULE_BASE_OFFSET) << 16) | \
+  (uint32_t)(code)
+#define SUCCESS(code) \
+  SUCCESS_OR_FAILURE(NS_ERROR_SEVERITY_SUCCESS, MODULE, code)
+#define FAILURE(code) \
+  SUCCESS_OR_FAILURE(NS_ERROR_SEVERITY_ERROR, MODULE, code)
+
+/**
+ * @name Standard return values
+ */
+
+/*@{*/
+
+enum class nsresult : uint32_t
+{
+  #undef ERROR
+  #define ERROR(key, val) key = val
+  #include "ErrorList.h"
+  #undef ERROR
+};
+
+/*
+ * enum classes don't place their initializers in the global scope, so we need
+ * constants for compatibility with old code.
+ */
+const nsresult
+  #define ERROR(key, val) key = nsresult::key
+  #include "ErrorList.h"
+  #undef ERROR
+;
+
+#undef SUCCESS_OR_FAILURE
+#undef SUCCESS
+#undef FAILURE
+
+/**
+ * @name Standard Error Handling Macros
+ * @return 0 or 1 (false/true with bool type for C++)
+ */
+
+inline uint32_t
+NS_FAILED_impl(nsresult aErr)
+{
+  return static_cast<uint32_t>(aErr) & 0x80000000;
+}
+#define NS_FAILED(_nsresult)    ((bool)MOZ_UNLIKELY(NS_FAILED_impl(_nsresult)))
+#define NS_SUCCEEDED(_nsresult) ((bool)MOZ_LIKELY(!NS_FAILED_impl(_nsresult)))
+
+/* Check that our enum type is actually uint32_t as expected */
+static_assert(((nsresult)0) < ((nsresult)-1),
+              "nsresult must be an unsigned type");
+static_assert(sizeof(nsresult) == sizeof(uint32_t),
+              "nsresult must be 32 bits");
+
+#define MOZ_ALWAYS_SUCCEEDS(expr) MOZ_ALWAYS_TRUE(NS_SUCCEEDED(expr))
+
+/**
+ * @name Standard Error Generating Macros
+ */
+
+#define NS_ERROR_GENERATE(sev, module, code) \
+  (nsresult)(((uint32_t)(sev) << 31) | \
+             ((uint32_t)(module + NS_ERROR_MODULE_BASE_OFFSET) << 16) | \
+             ((uint32_t)(code)))
+
+#define NS_ERROR_GENERATE_SUCCESS(module, code) \
+  NS_ERROR_GENERATE(NS_ERROR_SEVERITY_SUCCESS, module, code)
+
+#define NS_ERROR_GENERATE_FAILURE(module, code) \
+  NS_ERROR_GENERATE(NS_ERROR_SEVERITY_ERROR, module, code)
+
+ /*
+  * This will return the nsresult corresponding to the most recent NSPR failure
+  * returned by PR_GetError.
+  *
+  ***********************************************************************
+  *      Do not depend on this function. It will be going away!
+  ***********************************************************************
+  */
+extern nsresult
+NS_ErrorAccordingToNSPR();
+
+
+/**
+ * @name Standard Macros for retrieving error bits
+ */
+
+inline constexpr uint16_t
+NS_ERROR_GET_CODE(nsresult aErr)
+{
+  return uint32_t(aErr) & 0xffff;
+}
+inline constexpr uint16_t
+NS_ERROR_GET_MODULE(nsresult aErr)
+{
+  return ((uint32_t(aErr) >> 16) - NS_ERROR_MODULE_BASE_OFFSET) & 0x1fff;
+}
+inline bool
+NS_ERROR_GET_SEVERITY(nsresult aErr)
+{
+  return uint32_t(aErr) >> 31;
+}
+
+
+#ifdef _MSC_VER
+#pragma warning(disable: 4251) /* 'nsCOMPtr<class nsIInputStream>' needs to have dll-interface to be used by clients of class 'nsInputStream' */
+#pragma warning(disable: 4275) /* non dll-interface class 'nsISupports' used as base for dll-interface class 'nsIRDFNode' */
+#endif
+
+#endif
diff --git a/xpcom/base/nsErrorService.cpp b/xpcom/base/nsErrorService.cpp
new file mode 100644
index 000000000..d39b4f31e
--- /dev/null
+++ b/xpcom/base/nsErrorService.cpp
@@ -0,0 +1,50 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsErrorService.h"
+#include "nsCRTGlue.h"
+#include "nsAutoPtr.h"
+
+NS_IMPL_ISUPPORTS(nsErrorService, nsIErrorService)
+
+nsresult
+nsErrorService::Create(nsISupports* aOuter, const nsIID& aIID,
+                       void** aInstancePtr)
+{
+  if (NS_WARN_IF(aOuter)) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+  RefPtr<nsErrorService> serv = new nsErrorService();
+  return serv->QueryInterface(aIID, aInstancePtr);
+}
+
+NS_IMETHODIMP
+nsErrorService::RegisterErrorStringBundle(int16_t aErrorModule,
+                                          const char* aStringBundleURL)
+{
+  mErrorStringBundleURLMap.Put(aErrorModule, new nsCString(aStringBundleURL));
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsErrorService::UnregisterErrorStringBundle(int16_t aErrorModule)
+{
+  mErrorStringBundleURLMap.Remove(aErrorModule);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsErrorService::GetErrorStringBundle(int16_t aErrorModule, char** aResult)
+{
+  nsCString* bundleURL = mErrorStringBundleURLMap.Get(aErrorModule);
+  if (!bundleURL) {
+    return NS_ERROR_FAILURE;
+  }
+  *aResult = ToNewCString(*bundleURL);
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
diff --git a/xpcom/base/nsErrorService.h b/xpcom/base/nsErrorService.h
new file mode 100644
index 000000000..783c99ef9
--- /dev/null
+++ b/xpcom/base/nsErrorService.h
@@ -0,0 +1,37 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsErrorService_h__
+#define nsErrorService_h__
+
+#include "mozilla/Attributes.h"
+
+#include "nsIErrorService.h"
+#include "nsClassHashtable.h"
+#include "nsHashKeys.h"
+
+class nsErrorService final : public nsIErrorService
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIERRORSERVICE
+
+  nsErrorService()
+  {
+  }
+
+  static nsresult
+  Create(nsISupports* aOuter, const nsIID& aIID, void** aInstancePtr);
+
+private:
+  ~nsErrorService()
+  {
+  }
+
+  nsClassHashtable<nsUint32HashKey, nsCString> mErrorStringBundleURLMap;
+};
+
+#endif // nsErrorService_h__
diff --git a/xpcom/base/nsGZFileWriter.cpp b/xpcom/base/nsGZFileWriter.cpp
new file mode 100644
index 000000000..a5bc5be39
--- /dev/null
+++ b/xpcom/base/nsGZFileWriter.cpp
@@ -0,0 +1,111 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsGZFileWriter.h"
+#include "nsIFile.h"
+#include "nsString.h"
+#include "zlib.h"
+
+#ifdef XP_WIN
+#include <io.h>
+#define _dup dup
+#else
+#include <unistd.h>
+#endif
+
+NS_IMPL_ISUPPORTS(nsGZFileWriter, nsIGZFileWriter)
+
+nsGZFileWriter::nsGZFileWriter(Operation aMode)
+  : mMode(aMode)
+  , mInitialized(false)
+  , mFinished(false)
+{
+}
+
+nsGZFileWriter::~nsGZFileWriter()
+{
+  if (mInitialized && !mFinished) {
+    Finish();
+  }
+}
+
+NS_IMETHODIMP
+nsGZFileWriter::Init(nsIFile* aFile)
+{
+  if (NS_WARN_IF(mInitialized) ||
+      NS_WARN_IF(mFinished)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Get a FILE out of our nsIFile.  Convert that into a file descriptor which
+  // gzip can own.  Then close our FILE, leaving only gzip's fd open.
+
+  FILE* file;
+  nsresult rv = aFile->OpenANSIFileDesc(mMode == Create ? "wb" : "ab", &file);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+  return InitANSIFileDesc(file);
+}
+
+NS_IMETHODIMP
+nsGZFileWriter::InitANSIFileDesc(FILE* aFile)
+{
+  mGZFile = gzdopen(dup(fileno(aFile)), mMode == Create ? "wb" : "ab");
+  fclose(aFile);
+
+  // gzdopen returns nullptr on error.
+  if (NS_WARN_IF(!mGZFile)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  mInitialized = true;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsGZFileWriter::Write(const nsACString& aStr)
+{
+  if (NS_WARN_IF(!mInitialized) ||
+      NS_WARN_IF(mFinished)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // gzwrite uses a return value of 0 to indicate failure.  Otherwise, it
+  // returns the number of uncompressed bytes written.  To ensure we can
+  // distinguish between success and failure, don't call gzwrite when we have 0
+  // bytes to write.
+  if (aStr.IsEmpty()) {
+    return NS_OK;
+  }
+
+  // gzwrite never does a short write -- that is, the return value should
+  // always be either 0 or aStr.Length(), and we shouldn't have to call it
+  // multiple times in order to get it to read the whole buffer.
+  int rv = gzwrite(mGZFile, aStr.BeginReading(), aStr.Length());
+  if (NS_WARN_IF(rv != static_cast<int>(aStr.Length()))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsGZFileWriter::Finish()
+{
+  if (NS_WARN_IF(!mInitialized) ||
+      NS_WARN_IF(mFinished)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  mFinished = true;
+  gzclose(mGZFile);
+
+  // Ignore errors from gzclose; it's not like there's anything we can do about
+  // it, at this point!
+  return NS_OK;
+}
diff --git a/xpcom/base/nsGZFileWriter.h b/xpcom/base/nsGZFileWriter.h
new file mode 100644
index 000000000..4bb91173c
--- /dev/null
+++ b/xpcom/base/nsGZFileWriter.h
@@ -0,0 +1,55 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsGZFileWriter_h
+#define nsGZFileWriter_h
+
+#include "nsIGZFileWriter.h"
+#include "zlib.h"
+
+/**
+ * A simple class for writing .gz files.
+ */
+class nsGZFileWriter final : public nsIGZFileWriter
+{
+  virtual ~nsGZFileWriter();
+
+public:
+
+  enum Operation {
+    Append,
+    Create
+  };
+
+
+  explicit nsGZFileWriter(Operation aMode = Create);
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIGZFILEWRITER
+
+  /**
+   * nsIGZFileWriter exposes two non-virtual overloads of Write().  We
+   * duplicate them here so that you can call these overloads on a pointer to
+   * the concrete nsGZFileWriter class.
+   */
+  MOZ_MUST_USE nsresult Write(const char* aStr)
+  {
+    return nsIGZFileWriter::Write(aStr);
+  }
+
+  MOZ_MUST_USE nsresult Write(const char* aStr, uint32_t aLen)
+  {
+    return nsIGZFileWriter::Write(aStr, aLen);
+  }
+
+private:
+  Operation mMode;
+  bool mInitialized;
+  bool mFinished;
+  gzFile mGZFile;
+};
+
+#endif
diff --git a/xpcom/base/nsIConsoleListener.idl b/xpcom/base/nsIConsoleListener.idl
new file mode 100644
index 000000000..45e6fcb1f
--- /dev/null
+++ b/xpcom/base/nsIConsoleListener.idl
@@ -0,0 +1,18 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Used by the console service to notify listeners of new console messages.
+ */
+
+#include "nsISupports.idl"
+
+interface nsIConsoleMessage;
+
+[scriptable, function, uuid(35c400a4-5792-438c-b915-65e30d58d557)]
+interface nsIConsoleListener : nsISupports
+{
+    void observe(in nsIConsoleMessage aMessage);
+};
diff --git a/xpcom/base/nsIConsoleMessage.idl b/xpcom/base/nsIConsoleMessage.idl
new file mode 100644
index 000000000..bf233b28b
--- /dev/null
+++ b/xpcom/base/nsIConsoleMessage.idl
@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * This is intended as a base interface; implementations may want to
+ * provide an object that can be qi'ed to provide more specific
+ * message information.
+ */
+[scriptable, uuid(3aba9617-10e2-4839-83ae-2e6fc4df428b)]
+interface nsIConsoleMessage : nsISupports
+{
+    /** Log level constants. */
+    const uint32_t debug = 0;
+    const uint32_t info = 1;
+    const uint32_t warn = 2;
+    const uint32_t error = 3;
+
+    /**
+     * The log level of this message.
+     */
+    readonly attribute uint32_t logLevel;
+
+    /**
+     * The time (in milliseconds from the Epoch) that the message instance
+     * was initialised.
+     * The timestamp is initialized as JS_now/1000 so that it can be
+     * compared to Date.now in Javascript.
+     */
+    readonly attribute long long timeStamp;
+
+    [binaryname(MessageMoz)] readonly attribute wstring message;
+
+    AUTF8String toString();
+};
+
+%{ C++
+#define NS_CONSOLEMESSAGE_CID \
+{ 0x024efc9e, 0x54dc, 0x4844, { 0x80, 0x4b, 0x41, 0xd3, 0xf3, 0x69, 0x90, 0x73 }}
+%}
diff --git a/xpcom/base/nsIConsoleService.idl b/xpcom/base/nsIConsoleService.idl
new file mode 100644
index 000000000..fb9e906fb
--- /dev/null
+++ b/xpcom/base/nsIConsoleService.idl
@@ -0,0 +1,56 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIConsoleListener;
+interface nsIConsoleMessage;
+
+[scriptable, uuid(0eb81d20-c37e-42d4-82a8-ca9ae96bdf52)]
+interface nsIConsoleService : nsISupports
+{
+    void logMessage(in nsIConsoleMessage message);
+
+    /**
+     * Convenience method for logging simple messages.
+     */
+    void logStringMessage(in wstring message);
+
+    /**
+     * Get an array of all the messages logged so far.  If no messages
+     * are logged, this function will return a count of 0, but still
+     * will allocate one word for messages, so as to show up as a
+     * 0-length array when called from script.
+     */
+    void getMessageArray([optional] out uint32_t count,
+                         [retval, array, size_is(count)] out nsIConsoleMessage messages);
+
+    /**
+     * To guard against stack overflows from listeners that could log
+     * messages (it's easy to do this inadvertently from listeners
+     * implemented in JavaScript), we don't call any listeners when
+     * another error is already being logged.
+     */
+    void registerListener(in nsIConsoleListener listener);
+
+    /**
+     * Each registered listener should also be unregistered.
+     */
+    void unregisterListener(in nsIConsoleListener listener);
+
+    /**
+     * Clear the message buffer (e.g. for privacy reasons).
+     */
+    void reset();
+};
+
+
+%{ C++
+#define NS_CONSOLESERVICE_CID \
+{ 0x7e3ff85c, 0x1dd2, 0x11b2, { 0x8d, 0x4b, 0xeb, 0x45, 0x2c, 0xb0, 0xff, 0x40 }}
+
+#define NS_CONSOLESERVICE_CONTRACTID "@mozilla.org/consoleservice;1"
+%}
+
diff --git a/xpcom/base/nsICycleCollectorListener.idl b/xpcom/base/nsICycleCollectorListener.idl
new file mode 100644
index 000000000..cfdf9abe9
--- /dev/null
+++ b/xpcom/base/nsICycleCollectorListener.idl
@@ -0,0 +1,164 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+%{C++
+#include <stdio.h>
+
+class nsCycleCollectorLogger;
+%}
+
+[ptr] native FILE(FILE);
+[ptr] native nsCycleCollectorLoggerPtr (nsCycleCollectorLogger);
+interface nsIFile;
+
+/**
+ * A set of interfaces for recording the cycle collector's work. An instance
+ * of @mozilla.org/cycle-collector-logger;1 can be configured to enable various
+ * options, then passed to the cycle collector when it runs.
+ * Note that additional logging options are available by setting environment
+ * variables, as described at the top of nsCycleCollector.cpp.
+ */
+
+/**
+ * nsICycleCollectorHandler is the interface JS code should implement to
+ * receive the results logged by a @mozilla.org/cycle-collector-logger;1
+ * instance. Pass an instance of this to the logger's 'processNext' method
+ * after the collection has run. This will describe the objects the cycle
+ * collector visited, the edges it found, and the conclusions it reached
+ * about the liveness of objects.
+ *
+ * In more detail:
+ * - For each node in the graph:
+ *   - a call is made to either |noteRefCountedObject| or |noteGCedObject|, to
+ *     describe the node itself; and
+ *   - for each edge starting at that node, a call is made to |noteEdge|.
+ *
+ * - Then, a series of calls are made to:
+ *   - |describeRoot|, for reference-counted nodes that the CC has identified as
+ *     being alive because there are unknown references to those nodes.
+ *   - |describeGarbage|, for nodes the cycle collector has identified as garbage.
+ *
+ *   Any node not mentioned in a call to |describeRoot| or |describeGarbage| is
+ *   neither a root nor garbage. The cycle collector was able to find all of the
+ *   edges implied by the node's reference count.
+ */
+[scriptable, uuid(7f093367-1492-4b89-87af-c01dbc831246)]
+interface nsICycleCollectorHandler : nsISupports
+{
+    void noteRefCountedObject(in ACString aAddress,
+                              in unsigned long aRefCount,
+                              in ACString aObjectDescription);
+    void noteGCedObject(in ACString aAddress,
+                        in boolean aMarked,
+                        in ACString aObjectDescription,
+                        in ACString aCompartmentAddress);
+    void noteEdge(in ACString aFromAddress,
+                  in ACString aToAddress,
+                  in ACString aEdgeName);
+    void describeRoot(in ACString aAddress,
+                      in unsigned long aKnownEdges);
+    void describeGarbage(in ACString aAddress);
+};
+
+
+/**
+ * This interface allows replacing the log-writing backend for an
+ * nsICycleCollectorListener.  As this interface is also called while
+ * the cycle collector is running, it cannot be implemented in JS.
+ */
+[scriptable, builtinclass, uuid(3ad9875f-d0e4-4ac2-87e3-f127f6c02ce1)]
+interface nsICycleCollectorLogSink : nsISupports
+{
+  [noscript] void open(out FILE aGCLog, out FILE aCCLog);
+  void closeGCLog();
+  void closeCCLog();
+
+  // This string will appear somewhere in the log's filename.
+  attribute AString filenameIdentifier;
+
+  // This is the process ID; it can be changed if logging is on behalf
+  // of another process.
+  attribute int32_t processIdentifier;
+
+  // The GC log file, if logging to files.
+  readonly attribute nsIFile gcLog;
+
+  // The CC log file, if logging to files.
+  readonly attribute nsIFile ccLog;
+};
+
+
+/**
+ * This interface is used to configure some reporting options for the cycle
+ * collector. This interface cannot be implemented by JavaScript code, as it
+ * is called while the cycle collector is running.
+ *
+ * To analyze cycle collection data in JS:
+ *
+ * - Create an instance of @mozilla.org/cycle-collector-logger;1, which
+ *   implements this interface.
+ *
+ * - Set its |disableLog| property to true. This prevents the logger from
+ *   printing messages about each method call to a temporary log file.
+ *
+ * - Set its |wantAfterProcessing| property to true. This tells the logger
+ *   to record calls to its methods in memory. The |processNext| method
+ *   returns events from this record.
+ *
+ * - Perform a collection using the logger. For example, call
+ *   |nsIDOMWindowUtils|'s |garbageCollect| method, passing the logger as
+ *   the |aListener| argument.
+ *
+ * - When the collection is complete, loop calling the logger's
+ *   |processNext| method, passing a JavaScript object that implements
+ *   nsICycleCollectorHandler. This JS code is free to allocate and operate
+ *   on objects however it pleases: the cycle collector has finished its
+ *   work, and the JS code is simply consuming recorded data.
+ */
+[scriptable, builtinclass, uuid(703b53b6-24f6-40c6-9ea9-aeb2dc53d170)]
+interface nsICycleCollectorListener : nsISupports
+{
+    // Return a listener that directs the cycle collector to traverse
+    // objects that it knows won't be collectable.
+    //
+    // Note that even this listener will not visit every node in the heap;
+    // the cycle collector can't see the entire heap. But while this
+    // listener is in use, the collector disables some optimizations it
+    // normally uses to avoid certain classes of objects that are certainly
+    // alive. So, if your purpose is to get a view of the portion of the
+    // heap that is of interest to the cycle collector, and not simply find
+    // garbage, then you should use the listener this returns.
+    //
+    // Note that this does not necessarily return a new listener; rather, it may
+    // simply set a flag on this listener (a side effect!) and return it.
+    nsICycleCollectorListener allTraces();
+
+    // True if this listener will behave like one returned by allTraces().
+    readonly attribute boolean wantAllTraces;
+
+    // If true, do not log each method call to a temporary file.
+    // Initially false.
+    attribute boolean disableLog;
+
+    // If |disableLog| is false, this object will be sent the log text.
+    attribute nsICycleCollectorLogSink logSink;
+
+    // If true, record all method calls in memory, to be retrieved later
+    // using |processNext|. Initially false.
+    attribute boolean wantAfterProcessing;
+
+    // Report the next recorded event to |aHandler|, and remove it from the
+    // record. Return false if there isn't anything more to process.
+    //
+    // Note that we only record events to report here if our
+    // |wantAfterProcessing| property is true.
+    boolean processNext(in nsICycleCollectorHandler aHandler);
+
+    // Return the current object as an nsCycleCollectorLogger*, which is the
+    // only class that should be implementing this interface. We need the
+    // concrete implementation type to help the GC rooting analysis.
+    [noscript] nsCycleCollectorLoggerPtr asLogger();
+};
diff --git a/xpcom/base/nsIDebug2.idl b/xpcom/base/nsIDebug2.idl
new file mode 100644
index 000000000..4401f8a91
--- /dev/null
+++ b/xpcom/base/nsIDebug2.idl
@@ -0,0 +1,82 @@
+/* vim: set shiftwidth=4 tabstop=8 autoindent cindent expandtab: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* interface to expose information about calls to NS_DebugBreak */
+
+#include "nsISupports.idl"
+
+/**
+ *   For use by consumers in scripted languages (JavaScript, Java, Python,
+ *   Perl, ...).
+ *
+ *   @note C/C++ consumers who are planning to use the nsIDebug2 interface with
+ *   the "@mozilla.org/xpcom;1" contract should use NS_DebugBreak from xpcom
+ *   glue instead.
+ *
+ */
+
+[scriptable, uuid(9641dc15-10fb-42e3-a285-18be90a5c10b)]
+interface nsIDebug2 : nsISupports
+{
+    /**
+     * Whether XPCOM was compiled with DEBUG defined.  This often
+     * correlates to whether other code (e.g., Firefox, XULRunner) was
+     * compiled with DEBUG defined.
+     */
+    readonly attribute boolean isDebugBuild;
+
+    /**
+     * The number of assertions since process start.
+     */
+    readonly attribute long assertionCount;
+
+    /**
+     * Whether a debugger is currently attached.
+     * Supports Windows + Mac
+     */
+    readonly attribute bool isDebuggerAttached;
+
+    /**
+     * Show an assertion and trigger nsIDebug2.break().
+     *
+     * @param aStr assertion message
+     * @param aExpr expression that failed
+     * @param aFile file containing assertion
+     * @param aLine line number of assertion
+     */
+    void assertion(in string aStr,
+                   in string aExpr,
+                   in string aFile, 
+                   in long aLine);
+
+    /**
+     * Show a warning.
+     *
+     * @param aStr warning message
+     * @param aFile file containing assertion
+     * @param aLine line number of assertion
+     */
+    void warning(in string aStr,
+                 in string aFile,
+                 in long aLine);
+
+    /**
+     * Request to break into a debugger.
+     *
+     * @param aFile file containing break request
+     * @param aLine line number of break request
+     */
+    void break(in string aFile, 
+               in long aLine);
+
+    /**
+     * Request the process to trigger a fatal abort.
+     *
+     * @param aFile file containing abort request
+     * @param aLine line number of abort request
+     */
+    void abort(in string aFile, 
+               in long aLine);
+};
diff --git a/xpcom/base/nsIErrorService.idl b/xpcom/base/nsIErrorService.idl
new file mode 100644
index 000000000..9eeea2382
--- /dev/null
+++ b/xpcom/base/nsIErrorService.idl
@@ -0,0 +1,49 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * nsIErrorService: This is an interim service that allows nsresult codes to be mapped to 
+ * string bundles that can be used to look up error messages. String bundle keys can also
+ * be mapped. 
+ *
+ * This service will eventually get replaced by extending xpidl to allow errors to be defined.
+ * (http://bugzilla.mozilla.org/show_bug.cgi?id=13423).
+ */
+[scriptable, uuid(afe1f190-a3c2-11e3-a5e2-0800200c9a66)]
+interface nsIErrorService : nsISupports 
+{
+    /**
+     * Registers a string bundle URL for an error module. Error modules are obtained from
+     * nsresult code with NS_ERROR_GET_MODULE.
+     */
+    void registerErrorStringBundle(in short errorModule, in string stringBundleURL);
+
+    /**
+     * Unregisters a string bundle URL for an error module.
+     */
+    void unregisterErrorStringBundle(in short errorModule);
+
+    /**
+     * Retrieves a string bundle URL for an error module.
+     */
+    string getErrorStringBundle(in short errorModule);
+};
+
+%{C++
+
+// The global nsIErrorService:
+#define NS_ERRORSERVICE_NAME   "Error Service" 
+#define NS_ERRORSERVICE_CONTRACTID "@mozilla.org/xpcom/error-service;1"
+#define NS_ERRORSERVICE_CID                          \
+{ /* 744afd5e-5f8c-11d4-9877-00c04fa0cf4a */         \
+    0x744afd5e,                                      \
+    0x5f8c,                                          \
+    0x11d4,                                          \
+    {0x98, 0x77, 0x00, 0xc0, 0x4f, 0xa0, 0xcf, 0x4a} \
+}
+
+%}
diff --git a/xpcom/base/nsIException.idl b/xpcom/base/nsIException.idl
new file mode 100644
index 000000000..ff5a402ed
--- /dev/null
+++ b/xpcom/base/nsIException.idl
@@ -0,0 +1,86 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Interfaces for representing cross-language exceptions and stack traces.
+ */
+
+
+#include "nsISupports.idl"
+
+[scriptable, builtinclass, uuid(28bfb2a2-5ea6-4738-918b-049dc4d51f0b)]
+interface nsIStackFrame : nsISupports
+{
+    // see nsIProgrammingLanguage for list of language consts
+    readonly attribute uint32_t                language;
+    readonly attribute AUTF8String             languageName;
+    [implicit_jscontext]
+    readonly attribute AString                 filename;
+    [implicit_jscontext]
+    readonly attribute AString                 name;
+    // Valid line numbers begin at '1'. '0' indicates unknown.
+    [implicit_jscontext]
+    readonly attribute int32_t                 lineNumber;
+    [implicit_jscontext]
+    readonly attribute int32_t                 columnNumber;
+    readonly attribute AUTF8String             sourceLine;
+    [implicit_jscontext]
+    readonly attribute AString                 asyncCause;
+    [implicit_jscontext]
+    readonly attribute nsIStackFrame           asyncCaller;
+    [implicit_jscontext]
+    readonly attribute nsIStackFrame           caller;
+
+    // Returns a formatted stack string that looks like the sort of
+    // string that would be returned by .stack on JS Error objects.
+    // Only works on JS-language stack frames.
+    [implicit_jscontext]
+    readonly attribute AString                 formattedStack;
+
+    // Returns the underlying SavedFrame object for native JavaScript stacks,
+    // or null if this is not a native JavaScript stack frame.
+    readonly attribute jsval                   nativeSavedFrame;
+
+    [implicit_jscontext]
+    AUTF8String toString();
+};
+
+[scriptable, builtinclass, uuid(4371b5bf-6845-487f-8d9d-3f1e4a9badd2)]
+interface nsIException : nsISupports
+{
+    // A custom message set by the thrower.
+    [binaryname(MessageMoz)] readonly attribute AUTF8String message;
+    // The nsresult associated with this exception.
+    readonly attribute nsresult                result;
+    // The name of the error code (ie, a string repr of |result|)
+    readonly attribute AUTF8String             name;
+
+    // Filename location.  This is the location that caused the
+    // error, which may or may not be a source file location.
+    // For example, standard language errors would generally have
+    // the same location as their top stack entry.  File
+    // parsers may put the location of the file they were parsing,
+    // etc.
+
+    // null indicates "no data"
+    [implicit_jscontext]
+    readonly attribute AString                 filename;
+    // Valid line numbers begin at '1'. '0' indicates unknown.
+    [implicit_jscontext]
+    readonly attribute uint32_t                lineNumber;
+    // Valid column numbers begin at 0.
+    // We don't have an unambiguous indicator for unknown.
+    readonly attribute uint32_t                columnNumber;
+
+    // A stack trace, if available.
+    readonly attribute nsIStackFrame           location;
+
+    // Arbitary data for the implementation.
+    readonly attribute nsISupports             data;
+
+    // A generic formatter - make it suitable to print, etc.
+    [implicit_jscontext]
+    AUTF8String toString();
+};
diff --git a/xpcom/base/nsIGZFileWriter.idl b/xpcom/base/nsIGZFileWriter.idl
new file mode 100644
index 000000000..11e27f5c4
--- /dev/null
+++ b/xpcom/base/nsIGZFileWriter.idl
@@ -0,0 +1,82 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+%{C++
+#include "nsDependentString.h"
+#include <stdio.h>
+%}
+
+interface nsIFile;
+[ptr] native FILE(FILE);
+
+/**
+ * A simple interface for writing to a .gz file.
+ *
+ * Note that the file that this interface produces has a different format than
+ * what you'd get if you compressed your data as a gzip stream and dumped the
+ * result to a file.
+ *
+ * The standard gunzip tool cannot decompress a raw gzip stream, but can handle
+ * the files produced by this interface.
+ */
+[scriptable, uuid(6bd5642c-1b90-4499-ba4b-199f27efaba5)]
+interface nsIGZFileWriter : nsISupports
+{
+  /**
+   * Initialize this object.  We'll write our gzip'ed data to the given file,
+   * overwriting its contents if the file exists.
+   *
+   * init() will return an error if called twice.  It's an error to call any
+   * other method on this interface without first calling init().
+   */
+  [must_use] void init(in nsIFile file);
+
+  /**
+   * Alternate version of init() for use when the file is already opened;
+   * e.g., with a FileDescriptor passed over IPC.
+   */
+  [noscript, must_use] void initANSIFileDesc(in FILE file);
+
+  /**
+   * Write the given string to the file.
+   */
+  [must_use] void write(in AUTF8String str);
+
+  /*
+   * The following two overloads of Write() are C++ because we can't overload
+   * methods in XPIDL.  Anyway, they don't add much functionality for JS
+   * callers.
+   */
+  %{C++
+  /**
+   * Write the given char* to the file (not including the null-terminator).
+   */
+  MOZ_MUST_USE nsresult Write(const char* str)
+  {
+    return Write(str, strlen(str));
+  }
+
+  /**
+   * Write |length| bytes of |str| to the file.
+   */
+  MOZ_MUST_USE nsresult Write(const char* str, uint32_t len)
+  {
+    return Write(nsDependentCString(str, len));
+  }
+  %}
+
+  /**
+   * Close this nsIGZFileWriter.  Classes implementing nsIGZFileWriter will run
+   * this method when the underlying object is destroyed, so it's not strictly
+   * necessary to explicitly call it from your code.
+   *
+   * It's an error to call this method twice, and it's an error to call write()
+   * after finish() has been called.
+   */
+  void finish();
+};
diff --git a/xpcom/base/nsIID.h b/xpcom/base/nsIID.h
new file mode 100644
index 000000000..f2d788576
--- /dev/null
+++ b/xpcom/base/nsIID.h
@@ -0,0 +1,10 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __nsIID_h
+#define __nsIID_h
+#include "nsID.h"
+#endif /* __nsIID_h */
diff --git a/xpcom/base/nsIInterfaceRequestor.idl b/xpcom/base/nsIInterfaceRequestor.idl
new file mode 100644
index 000000000..9727c53cb
--- /dev/null
+++ b/xpcom/base/nsIInterfaceRequestor.idl
@@ -0,0 +1,36 @@
+/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * The nsIInterfaceRequestor interface defines a generic interface for 
+ * requesting interfaces that a given object might provide access to.
+ * This is very similar to QueryInterface found in nsISupports.  
+ * The main difference is that interfaces returned from GetInterface()
+ * are not required to provide a way back to the object implementing this 
+ * interface.  The semantics of QI() dictate that given an interface A that 
+ * you QI() on to get to interface B, you must be able to QI on B to get back 
+ * to A.  This interface however allows you to obtain an interface C from A 
+ * that may or most likely will not have the ability to get back to A. 
+ */
+
+[scriptable, uuid(033A1470-8B2A-11d3-AF88-00A024FFC08C)]
+interface nsIInterfaceRequestor : nsISupports
+{
+   /**
+    * Retrieves the specified interface pointer.
+    *
+    * @param uuid The IID of the interface being requested.
+    * @param result [out] The interface pointer to be filled in if
+    *               the interface is accessible.
+    * @throws NS_NOINTERFACE - interface not accessible.
+    * @throws NS_ERROR* - method failure.
+    */
+	void getInterface(in nsIIDRef uuid, 
+                      [iid_is(uuid),retval] out nsQIResult result);
+};
+
diff --git a/xpcom/base/nsIMacUtils.idl b/xpcom/base/nsIMacUtils.idl
new file mode 100644
index 000000000..9a60df47c
--- /dev/null
+++ b/xpcom/base/nsIMacUtils.idl
@@ -0,0 +1,32 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * nsIMacUtils: Generic globally-available Mac-specific utilities.
+ */
+
+[scriptable, uuid(5E9072D7-FF95-455E-9466-8AF9841A72EC)]
+interface nsIMacUtils : nsISupports
+{
+  /**
+   * True when the main executable is a fat file supporting at least
+   * ppc and x86 (universal binary).
+   */
+  readonly attribute boolean isUniversalBinary;
+
+  /**
+   * Returns a string containing a list of architectures delimited
+   * by "-". Architecture sets are always in the same order:
+   * ppc > i386 > ppc64 > x86_64 > (future additions)
+   */
+  readonly attribute AString architecturesInBinary;
+
+  /**
+   * True when running under binary translation (Rosetta).
+   */
+  readonly attribute boolean isTranslated;
+};
diff --git a/xpcom/base/nsIMemory.idl b/xpcom/base/nsIMemory.idl
new file mode 100644
index 000000000..0c1a050b7
--- /dev/null
+++ b/xpcom/base/nsIMemory.idl
@@ -0,0 +1,78 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ *
+ * nsIMemory: interface to allocate and deallocate memory. Also provides
+ * for notifications in low-memory situations.
+ *
+ * The frozen exported symbols moz_xmalloc, moz_xrealloc, and free
+ * provide a more efficient way to access XPCOM memory allocation. Using
+ * those symbols is preferred to using the methods on this interface.
+ *
+ * A client that wishes to be notified of low memory situations (for
+ * example, because the client maintains a large memory cache that
+ * could be released when memory is tight) should register with the
+ * observer service (see nsIObserverService) using the topic 
+ * "memory-pressure".  There are specific types of notications 
+ * that can occur.  These types will be passed as the |aData| 
+ * parameter of the of the "memory-pressure" notification: 
+ * 
+ * "low-memory"
+ * This will be passed as the extra data when the pressure 
+ * observer is being asked to flush for low-memory conditions.
+ *
+ * "low-memory-ongoing"
+ * This will be passed when we continue to be in a low-memory
+ * condition and we want to flush caches and do other cheap
+ * forms of memory minimization, but heavy handed approaches like
+ * a GC are unlikely to succeed.
+ *
+ * "-no-forward"
+ * This is appended to the above two parameters when the resulting
+ * notification should not be forwarded to the child processes.
+ *
+ * "heap-minimize"
+ * This will be passed as the extra data when the pressure 
+ * observer is being asked to flush because of a heap minimize 
+ * call.
+ *
+ * "alloc-failure"
+ * This will be passed as the extra data when the pressure 
+ * observer has been asked to flush because a malloc() or 
+ * realloc() has failed.
+ *
+ * "lowering-priority"
+ * This will be passed as the extra data when the priority of a child
+ * process is lowered. The pressure observers could take the chance to
+ * clear caches that could be easily regenerated. This type of
+ * notification only appears in child processes.
+ */
+
+[scriptable, uuid(1e004834-6d8f-425a-bc9c-a2812ed43bb7)]
+interface nsIMemory : nsISupports
+{
+    /**
+     * Attempts to shrink the heap.
+     * @param immediate - if true, heap minimization will occur
+     *   immediately if the call was made on the main thread. If
+     *   false, the flush will be scheduled to happen when the app is
+     *   idle.
+     * @throws NS_ERROR_FAILURE if 'immediate' is set an the call
+     *   was not on the application's main thread.
+     */
+    void heapMinimize(in boolean immediate);
+
+    /**
+     * This predicate can be used to determine if the platform is a "low-memory"
+     * platform. Callers may use this to dynamically tune their behaviour
+     * to favour reduced memory usage at the expense of performance. The value
+     * returned by this function will not change over the lifetime of the process.
+     */
+    boolean isLowMemoryPlatform();
+};
+
diff --git a/xpcom/base/nsIMemoryInfoDumper.idl b/xpcom/base/nsIMemoryInfoDumper.idl
new file mode 100644
index 000000000..7e08503a4
--- /dev/null
+++ b/xpcom/base/nsIMemoryInfoDumper.idl
@@ -0,0 +1,162 @@
+/* -*- Mode: C++; tab-width: 50; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIFile;
+interface nsICycleCollectorLogSink;
+
+[scriptable, function, uuid(2dea18fc-fbfa-4bf7-ad45-0efaf5495f5e)]
+interface nsIFinishDumpingCallback : nsISupports
+{
+  void callback(in nsISupports data);
+};
+
+/**
+ * Callback interface for |dumpGCAndCCLogsToFile|, below.  Note that
+ * these method calls can occur before |dumpGCAndCCLogsToFile|
+ * returns.
+ */
+[scriptable, uuid(dc1b2b24-65bd-441b-b6bd-cb5825a7ed14)]
+interface nsIDumpGCAndCCLogsCallback : nsISupports
+{
+  /**
+   * Called whenever a process has successfully finished dumping its GC/CC logs.
+   * Incomplete dumps (e.g., if the child crashes or is killed due to memory
+   * exhaustion) are not reported.
+   *
+   * @param aGCLog The file that the GC log was written to.
+   *
+   * @param aCCLog The file that the CC log was written to.
+   *
+   * @param aIsParent indicates whether this log file pair is from the
+   * parent process.
+   */
+  void onDump(in nsIFile aGCLog,
+              in nsIFile aCCLog,
+              in bool aIsParent);
+
+  /**
+   * Called when GC/CC logging has finished, after all calls to |onDump|.
+   */
+  void onFinish();
+};
+
+[scriptable, builtinclass, uuid(48541b74-47ee-4a62-9557-7f4b809bda5c)]
+interface nsIMemoryInfoDumper : nsISupports
+{
+  /**
+   * This dumps gzipped memory reports for this process and its child
+   * processes.  If a file of the given name exists, it will be overwritten.
+   *
+   * @param aFilename The output file.
+   *
+   * @param aFinishDumping The callback called on completion.
+   *
+   * @param aFinishDumpingData The environment for the callback.
+   *
+   * @param aAnonymize Should the reports be anonymized?
+   *
+   * Sample output, annotated with comments for explanatory purposes.
+   *
+   * {
+   *   // The version number of the format, which will be incremented each time
+   *   // backwards-incompatible changes are made. A mandatory integer.
+   *   "version": 1
+   *
+   *   // Equal to nsIMemoryReporterManager::hasMozMallocUsableSize. A
+   *   // mandatory boolean.
+   *   "hasMozMallocUsableSize": true,
+   *
+   *   // The memory reports. A mandatory array.
+   *   "reports": [
+   *     // The properties correspond to the arguments of
+   *     // nsIHandleReportCallback::callback. Every one is mandatory.
+   *     {"process":"Main Process (pid 12345)", "path":"explicit/foo/bar",
+   *      "kind":1, "units":0, "amount":2000000, "description":"Foo bar."},
+   *     {"process":"Main Process (pid 12345)", "path":"heap-allocated",
+   *      "kind":1, "units":0, "amount":3000000, "description":"Heap allocated."},
+   *     {"process":"Main Process (pid 12345)", "path":"vsize",
+   *      "kind":1, "units":0, "amount":10000000, "description":"Vsize."}
+   *   ]
+   * }
+   */
+  void dumpMemoryReportsToNamedFile(in AString aFilename,
+                                    in nsIFinishDumpingCallback aFinishDumping,
+                                    in nsISupports aFinishDumpingData,
+                                    in boolean aAnonymize);
+
+  /**
+   * Similar to dumpMemoryReportsToNamedFile, this method dumps gzipped memory
+   * reports for this process and its child processes to files in the tmp
+   * directory called memory-reports-<identifier>-<pid>.json.gz (or something
+   * similar, such as memory-reports-<identifier>-<pid>-1.json.gz; no existing
+   * file will be overwritten).
+   *
+   * If DMD is enabled, this method also dumps gzipped DMD output for this
+   * process and its child processes to files in the tmp directory called
+   * dmd-<identifier>-<pid>.txt.gz (or something similar; again, no existing
+   * file will be overwritten).
+   *
+   * @param aIdentifier this identifier will appear in the filename of our
+   *   about:memory dump and those of our children.
+   *
+   *   If the identifier is empty, the implementation may set it arbitrarily
+   *   and use that new value for its own dump and the dumps of its child
+   *   processes.  For example, the implementation may set |aIdentifier| to the
+   *   number of seconds since the epoch.
+   *
+   * @param aAnonymize Should the reports be anonymized?
+   *
+   * @param aMinimizeMemoryUsage indicates whether we should run a series of
+   *   gc/cc's in an attempt to reduce our memory usage before collecting our
+   *   memory report.
+   */
+  void dumpMemoryInfoToTempDir(
+    in AString aIdentifier,
+    in boolean aAnonymize,
+    in boolean aMinimizeMemoryUsage);
+
+  /**
+   * Dump GC and CC logs to files in the OS's temp directory (or in
+   * $MOZ_CC_LOG_DIRECTORY, if that environment variable is specified).
+   *
+   * @param aIdentifier If aIdentifier is non-empty, this string will appear in
+   *   the filenames of the logs we create (both for this process and, if
+   *   aDumpChildProcesses is true, for our child processes).
+   *
+   *   If aIdentifier is empty, the implementation may set it to an
+   *   arbitrary value; for example, it may set aIdentifier to the number
+   *   of seconds since the epoch.
+   *
+   * @param aDumpAllTraces indicates whether we should run an all-traces CC
+   *   log.  An all-traces log visits all objects currently eligible for cycle
+   *   collection, while a non-all-traces log avoids visiting some objects
+   *   which we know are reachable.
+   *
+   *   All-traces logs are much bigger than the alternative, but they may be
+   *   helpful when trying to understand why a particular object is alive.  For
+   *   example, a non-traces-log will skip references held by an active
+   *   document; if your object is being held alive by such a document, you
+   *   probably want to see those references.
+   *
+   * @param aDumpChildProcesses indicates whether we should call
+   *   DumpGCAndCCLogsToFile in our child processes.  If so, the child processes
+   *   will dump their children, and so on.
+   *
+   */
+  void dumpGCAndCCLogsToFile(in AString aIdentifier,
+                             in bool aDumpAllTraces,
+                             in bool aDumpChildProcesses,
+                             in nsIDumpGCAndCCLogsCallback aCallback);
+
+  /**
+   * Like |dumpGCAndCCLogsToFile|, but sends the logs to the given log
+   * sink object instead of accessing the filesystem directly, and
+   * dumps the current process only.
+   */
+  void dumpGCAndCCLogsToSink(in bool aDumpAllTraces,
+                             in nsICycleCollectorLogSink aSink);
+};
diff --git a/xpcom/base/nsIMemoryReporter.idl b/xpcom/base/nsIMemoryReporter.idl
new file mode 100644
index 000000000..9617877df
--- /dev/null
+++ b/xpcom/base/nsIMemoryReporter.idl
@@ -0,0 +1,581 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+%{C++
+#include <stdio.h>
+%}
+
+interface mozIDOMWindowProxy;
+interface nsIRunnable;
+interface nsISimpleEnumerator;
+[ptr] native FILE(FILE);
+
+/*
+ * Memory reporters measure Firefox's memory usage.  They are primarily used to
+ * generate the about:memory page.  You should read
+ * https://developer.mozilla.org/en-US/docs/Mozilla/Performance/Memory_reporting
+ * before writing a memory reporter.
+ */
+
+[scriptable, function, uuid(62ef0e1c-dbd6-11e3-aa75-3c970e9f4238)]
+interface nsIMemoryReporterCallback : nsISupports
+{
+  /*
+   * The arguments to the callback are as follows.
+   *
+   *
+   * |process|  The name of the process containing this reporter.  Each
+   * reporter initially has "" in this field, indicating that it applies to the
+   * current process.  (This is true even for reporters in a child process.)
+   * When a reporter from a child process is copied into the main process, the
+   * copy has its 'process' field set appropriately.
+   *
+   *
+   * |path|  The path that this memory usage should be reported under.  Paths
+   * are '/'-delimited, eg. "a/b/c".
+   *
+   * Each reporter can be viewed as representing a leaf node in a tree.
+   * Internal nodes of the tree don't have reporters.  So, for example, the
+   * reporters "explicit/a/b", "explicit/a/c", "explicit/d/e", and
+   * "explicit/d/f" define this tree:
+   *
+   *   explicit
+   *   |--a
+   *   |  |--b [*]
+   *   |  \--c [*]
+   *   \--d
+   *      |--e [*]
+   *      \--f [*]
+   *
+   * Nodes marked with a [*] have a reporter.  Notice that the internal
+   * nodes are implicitly defined by the paths.
+   *
+   * Nodes within a tree should not overlap measurements, otherwise the
+   * parent node measurements will be double-counted.  So in the example
+   * above, |b| should not count any allocations counted by |c|, and vice
+   * versa.
+   *
+   * All nodes within each tree must have the same units.
+   *
+   * If you want to include a '/' not as a path separator, e.g. because the
+   * path contains a URL, you need to convert each '/' in the URL to a '\'.
+   * Consumers of the path will undo this change.  Any other '\' character
+   * in a path will also be changed.  This is clumsy but hasn't caused any
+   * problems so far.
+   *
+   * The paths of all reporters form a set of trees.  Trees can be
+   * "degenerate", i.e. contain a single entry with no '/'.
+   *
+   *
+   * |kind|  There are three kinds of memory reporters.
+   *
+   *  - HEAP: reporters measuring memory allocated by the heap allocator,
+   *    e.g. by calling malloc, calloc, realloc, memalign, operator new, or
+   *    operator new[].  Reporters in this category must have units
+   *    UNITS_BYTES.
+   *
+   *  - NONHEAP: reporters measuring memory which the program explicitly
+   *    allocated, but does not live on the heap.  Such memory is commonly
+   *    allocated by calling one of the OS's memory-mapping functions (e.g.
+   *    mmap, VirtualAlloc, or vm_allocate).  Reporters in this category
+   *    must have units UNITS_BYTES.
+   *
+   *  - OTHER: reporters which don't fit into either of these categories.
+   *    They can have any units.
+   *
+   * The kind only matters for reporters in the "explicit" tree;
+   * aboutMemory.js uses it to calculate "heap-unclassified".
+   *
+   *
+   * |units|  The units on the reporter's amount.  One of the following.
+   *
+   *  - BYTES: The amount contains a number of bytes.
+   *
+   *  - COUNT: The amount is an instantaneous count of things currently in
+   *    existence.  For instance, the number of tabs currently open would have
+   *    units COUNT.
+   *
+   *  - COUNT_CUMULATIVE: The amount contains the number of times some event
+   *    has occurred since the application started up.  For instance, the
+   *    number of times the user has opened a new tab would have units
+   *    COUNT_CUMULATIVE.
+   *
+   *    The amount returned by a reporter with units COUNT_CUMULATIVE must
+   *    never decrease over the lifetime of the application.
+   *
+   *  - PERCENTAGE: The amount contains a fraction that should be expressed as
+   *    a percentage.  NOTE!  The |amount| field should be given a value 100x
+   *    the actual percentage;  this number will be divided by 100 when shown.
+   *    This allows a fractional percentage to be shown even though |amount| is
+   *    an integer.  E.g. if the actual percentage is 12.34%, |amount| should
+   *    be 1234.
+   *
+   *    Values greater than 100% are allowed.
+   *
+   *
+   * |amount|  The numeric value reported by this memory reporter.  Accesses
+   * can fail if something goes wrong when getting the amount.
+   *
+   *
+   * |description|  A human-readable description of this memory usage report.
+   */
+  void callback(in ACString process, in AUTF8String path, in int32_t kind,
+                in int32_t units, in int64_t amount,
+                in AUTF8String description, in nsISupports data);
+};
+
+/*
+ * An nsIMemoryReporter reports one or more memory measurements via a
+ * callback function which is called once for each measurement.
+ *
+ * An nsIMemoryReporter that reports a single measurement is sometimes called a
+ * "uni-reporter".  One that reports multiple measurements is sometimes called
+ * a "multi-reporter".
+ *
+ * aboutMemory.js is the most important consumer of memory reports.  It
+ * places the following constraints on reports.
+ *
+ * - All reports within a single sub-tree must have the same units.
+ *
+ * - There may be an "explicit" tree.  If present, it represents
+ *   non-overlapping regions of memory that have been explicitly allocated with
+ *   an OS-level allocation (e.g. mmap/VirtualAlloc/vm_allocate) or a
+ *   heap-level allocation (e.g. malloc/calloc/operator new).  Reporters in
+ *   this tree must have kind HEAP or NONHEAP, units BYTES.
+ *
+ * It is preferred, but not required, that report descriptions use complete
+ * sentences (i.e. start with a capital letter and end with a period, or
+ * similar).
+ */
+[scriptable, uuid(92a36db1-46bd-4fe6-988e-47db47236d8b)]
+interface nsIMemoryReporter : nsISupports
+{
+  /*
+   * Run the reporter.
+   *
+   * If |anonymize| is true, the memory reporter should anonymize any
+   * privacy-sensitive details in memory report paths, by replacing them with a
+   * string such as "<anonymized>". Anonymized memory reports may be sent
+   * automatically via crash reports or telemetry.
+   *
+   * The following things are considered privacy-sensitive.
+   *
+   * - Content domains and URLs, and information derived from them.
+   * - Content data, such as strings.
+   * - Details about content code, such as filenames, function names or stack
+   *   traces.
+   * - Details about or data from the user's system, such as filenames.
+   * - Running apps.
+   *
+   * In short, anything that could identify parts of the user's browsing
+   * history is considered privacy-sensitive.
+   *
+   * The following thing are not considered privacy-sensitive.
+   *
+   * - Chrome domains and URLs.
+   * - Information about installed extensions.
+   */
+  void collectReports(in nsIMemoryReporterCallback callback,
+                      in nsISupports data,
+                      in boolean anonymize);
+
+  /*
+   * Kinds. See the |kind| comment in nsIMemoryReporterCallback.
+   */
+  const int32_t KIND_NONHEAP = 0;
+  const int32_t KIND_HEAP    = 1;
+  const int32_t KIND_OTHER   = 2;
+
+  /*
+   * Units. See the |units| comment in nsIMemoryReporterCallback.
+   */
+  const int32_t UNITS_BYTES = 0;
+  const int32_t UNITS_COUNT = 1;
+  const int32_t UNITS_COUNT_CUMULATIVE = 2;
+  const int32_t UNITS_PERCENTAGE = 3;
+};
+
+[scriptable, function, uuid(548b3909-c04d-4ca6-8466-b8bee3837457)]
+interface nsIFinishReportingCallback : nsISupports
+{
+  void callback(in nsISupports data);
+};
+
+[scriptable, builtinclass, uuid(2998574d-8993-407a-b1a5-8ad7417653e1)]
+interface nsIMemoryReporterManager : nsISupports
+{
+  /*
+   * Initialize.
+   */
+  [must_use] void init();
+
+  /*
+   * Register the given nsIMemoryReporter.  The Manager service will hold a
+   * strong reference to the given reporter, and will be responsible for freeing
+   * the reporter at shutdown.  You may manually unregister the reporter with
+   * unregisterStrongReporter() at any point.
+   */
+  void registerStrongReporter(in nsIMemoryReporter reporter);
+  void registerStrongAsyncReporter(in nsIMemoryReporter reporter);
+
+  /*
+   * Like registerReporter, but the Manager service will hold a weak reference
+   * via a raw pointer to the given reporter.  The reporter should be
+   * unregistered before shutdown.
+   * You cannot register JavaScript components with this function!  Always
+   * register your JavaScript components with registerStrongReporter().
+   */
+  void registerWeakReporter(in nsIMemoryReporter reporter);
+  void registerWeakAsyncReporter(in nsIMemoryReporter reporter);
+
+  /*
+   * Unregister the given memory reporter, which must have been registered with
+   * registerStrongReporter().  You normally don't need to unregister your
+   * strong reporters, as nsIMemoryReporterManager will take care of that at
+   * shutdown.
+   */
+  void unregisterStrongReporter(in nsIMemoryReporter reporter);
+
+  /*
+   * Unregister the given memory reporter, which must have been registered with
+   * registerWeakReporter().
+   */
+  void unregisterWeakReporter(in nsIMemoryReporter reporter);
+
+  /*
+   * These functions should only be used for testing purposes.
+   */
+  void blockRegistrationAndHideExistingReporters();
+  void unblockRegistrationAndRestoreOriginalReporters();
+  void registerStrongReporterEvenIfBlocked(in nsIMemoryReporter aReporter);
+
+  /*
+   * Get memory reports for the current process and all child processes.
+   * |handleReport| is called for each report, and |finishReporting| is called
+   * once all reports have been handled.
+   *
+   * |finishReporting| is called even if, for example, some child processes
+   * fail to report back.  However, calls to this method will silently and
+   * immediately abort -- and |finishReporting| will not be called -- if a
+   * previous getReports() call is still in flight, i.e. if it has not yet
+   * finished invoking |finishReporting|.  The silent abort is because the
+   * in-flight request will finish soon, and the caller would very likely just
+   * catch and ignore any error anyway.
+   *
+   * If |anonymize| is true, it indicates that the memory reporters should
+   * anonymize any privacy-sensitive data (see above).
+   */
+  void getReports(in nsIMemoryReporterCallback handleReport,
+                  in nsISupports handleReportData,
+                  in nsIFinishReportingCallback finishReporting,
+                  in nsISupports finishReportingData,
+                  in boolean anonymize);
+
+  /*
+   * As above, but: If |minimizeMemoryUsage| is true, then each process will
+   * minimize its memory usage (see the |minimizeMemoryUsage| method) before
+   * gathering its report.  If DMD is enabled and |DMDDumpIdent| is non-empty
+   * then write a DMD report to a file in the usual temporary directory (see
+   * |dumpMemoryInfoToTempDir| in |nsIMemoryInfoDumper|.)
+   */
+  [noscript] void
+    getReportsExtended(in nsIMemoryReporterCallback handleReport,
+                       in nsISupports handleReportData,
+                       in nsIFinishReportingCallback finishReporting,
+                       in nsISupports finishReportingData,
+                       in boolean anonymize,
+                       in boolean minimizeMemoryUsage,
+                       in AString DMDDumpIdent);
+
+  /*
+   * As above, but if DMD is enabled and |DMDFile| is non-null then
+   * write a DMD report to that file and close it.
+   */
+  [noscript] void
+    getReportsForThisProcessExtended(in nsIMemoryReporterCallback handleReport,
+                                     in nsISupports handleReportData,
+                                     in boolean anonymize,
+                                     in FILE DMDFile,
+                                     in nsIFinishReportingCallback finishReporting,
+                                     in nsISupports finishReportingData);
+
+  /*
+   * Called by an asynchronous memory reporter upon completion.
+   */
+  [noscript] void endReport();
+
+  /*
+   * The memory reporter manager, for the most part, treats reporters
+   * registered with it as a black box.  However, there are some
+   * "distinguished" amounts (as could be reported by a memory reporter) that
+   * the manager provides as attributes, because they are sufficiently
+   * interesting that we want external code (e.g. telemetry) to be able to rely
+   * on them.
+   *
+   * Note that these are not reporters and so getReports() does not look at
+   * them.  However, distinguished amounts can be embedded in a reporter.
+   *
+   * Access to these attributes can fail.  In particular, some of them are not
+   * available on all platforms.
+   *
+   * If you add a new distinguished amount, please update
+   * toolkit/components/aboutmemory/tests/test_memoryReporters.xul.
+   *
+   * |vsize| (UNITS_BYTES)  The virtual size, i.e. the amount of address space
+   * taken up.
+   *
+   * |vsizeMaxContiguous| (UNITS_BYTES)  The size of the largest contiguous
+   * block of virtual memory.
+   *
+   * |resident| (UNITS_BYTES)  The resident size (a.k.a. RSS or physical memory
+   * used).
+   *
+   * |residentFast| (UNITS_BYTES)  This is like |resident|, but on Mac OS
+   * |resident| can purge pages, which is slow.  It also affects the result of
+   * |residentFast|, and so |resident| and |residentFast| should not be used
+   * together.
+   *
+   * |residentPeak| (UNITS_BYTES)  The peak resident size.
+   *
+   * |residentUnique| (UNITS_BYTES)  The unique set size (a.k.a. USS).
+   *
+   * |heapAllocated| (UNITS_BYTES)  Memory mapped by the heap allocator.
+   *
+   * |heapOverheadFraction| (UNITS_PERCENTAGE)  In the heap allocator, this is
+   * the fraction of committed heap bytes that are overhead. Like all
+   * UNITS_PERCENTAGE measurements, its amount is multiplied by 100x so it can
+   * be represented by an int64_t.
+   *
+   * |JSMainRuntimeGCHeap| (UNITS_BYTES)  Size of the main JS runtime's GC
+   * heap.
+   *
+   * |JSMainRuntimeTemporaryPeak| (UNITS_BYTES)  Peak size of the transient
+   * storage in the main JSRuntime.
+   *
+   * |JSMainRuntimeCompartments{System,User}| (UNITS_COUNT)  The number of
+   * {system,user} compartments in the main JS runtime.
+   *
+   * |imagesContentUsedUncompressed| (UNITS_BYTES)  Memory used for decoded
+   * raster images in content.
+   *
+   * |storageSQLite| (UNITS_BYTES)  Memory used by SQLite.
+   *
+   * |lowMemoryEvents{Virtual,Physical}| (UNITS_COUNT_CUMULATIVE)  The number
+   * of low-{virtual,physical}-memory events that have occurred since the
+   * process started.
+   *
+   * |ghostWindows| (UNITS_COUNT)  The number of ghost windows.
+   *
+   * |pageFaultsHard| (UNITS_COUNT_CUMULATIVE)  The number of hard (a.k.a.
+   * major) page faults that have occurred since the process started.
+   */
+  [must_use] readonly attribute int64_t vsize;
+  [must_use] readonly attribute int64_t vsizeMaxContiguous;
+  [must_use] readonly attribute int64_t resident;
+  [must_use] readonly attribute int64_t residentFast;
+  [must_use] readonly attribute int64_t residentPeak;
+  [must_use] readonly attribute int64_t residentUnique;
+
+  [must_use] readonly attribute int64_t heapAllocated;
+  [must_use] readonly attribute int64_t heapOverheadFraction;
+
+  [must_use] readonly attribute int64_t JSMainRuntimeGCHeap;
+  [must_use] readonly attribute int64_t JSMainRuntimeTemporaryPeak;
+  [must_use] readonly attribute int64_t JSMainRuntimeCompartmentsSystem;
+  [must_use] readonly attribute int64_t JSMainRuntimeCompartmentsUser;
+
+  [must_use] readonly attribute int64_t imagesContentUsedUncompressed;
+
+  [must_use] readonly attribute int64_t storageSQLite;
+
+  [must_use] readonly attribute int64_t lowMemoryEventsVirtual;
+  [must_use] readonly attribute int64_t lowMemoryEventsPhysical;
+
+  [must_use] readonly attribute int64_t ghostWindows;
+
+  [must_use] readonly attribute int64_t pageFaultsHard;
+
+  /*
+   * This attribute indicates if moz_malloc_usable_size() works.
+   */
+  [infallible] readonly attribute boolean hasMozMallocUsableSize;
+
+  /*
+   * These attributes indicate DMD's status. "Enabled" means enabled at
+   * build-time.
+   */
+  [infallible] readonly attribute boolean isDMDEnabled;
+  [infallible] readonly attribute boolean isDMDRunning;
+
+  /*
+   * Run a series of GC/CC's in an attempt to minimize the application's memory
+   * usage.  When we're finished, we invoke the given runnable if it's not
+   * null.
+   */
+  [must_use] void minimizeMemoryUsage(in nsIRunnable callback);
+
+  /*
+   * Measure the memory that is known to be owned by this tab, split up into
+   * several broad categories.  Note that this will be an underestimate of the
+   * true number, due to imperfect memory reporter coverage (corresponding to
+   * about:memory's "heap-unclassified"), and due to some memory shared between
+   * tabs not being counted.
+   *
+   * The time taken for the measurement (split into JS and non-JS parts) is
+   * also returned.
+   */
+  [must_use]
+  void sizeOfTab(in mozIDOMWindowProxy window,
+                 out int64_t jsObjectsSize, out int64_t jsStringsSize,
+                 out int64_t jsOtherSize, out int64_t domSize,
+                 out int64_t styleSize, out int64_t otherSize,
+                 out int64_t totalSize,
+                 out double jsMilliseconds, out double nonJSMilliseconds);
+};
+
+%{C++
+
+#include "js/TypeDecls.h"
+#include "nsStringGlue.h"
+#include "nsTArray.h"
+
+class nsPIDOMWindowOuter;
+
+// nsIHandleReportCallback is a better name, but keep nsIMemoryReporterCallback
+// around for backwards compatibility.
+typedef nsIMemoryReporterCallback nsIHandleReportCallback;
+
+namespace mozilla {
+
+// All the following registration/unregistration functions don't use
+// MOZ_MUST_USE because ignoring failures is common and reasonable.
+
+// Register a memory reporter.  The manager service will hold a strong
+// reference to this reporter.
+XPCOM_API(nsresult) RegisterStrongMemoryReporter(nsIMemoryReporter* aReporter);
+XPCOM_API(nsresult) RegisterStrongAsyncMemoryReporter(nsIMemoryReporter* aReporter);
+
+// Register a memory reporter.  The manager service will hold a weak reference
+// to this reporter.
+XPCOM_API(nsresult) RegisterWeakMemoryReporter(nsIMemoryReporter* aReporter);
+XPCOM_API(nsresult) RegisterWeakAsyncMemoryReporter(nsIMemoryReporter* aReporter);
+
+// Unregister a strong memory reporter.
+XPCOM_API(nsresult) UnregisterStrongMemoryReporter(nsIMemoryReporter* aReporter);
+
+// Unregister a weak memory reporter.
+XPCOM_API(nsresult) UnregisterWeakMemoryReporter(nsIMemoryReporter* aReporter);
+
+// The memory reporter manager provides access to several distinguished
+// amounts via attributes.  Some of these amounts are provided by Gecko
+// components that cannot be accessed directly from XPCOM code.  So we provide
+// the following functions for those components to be registered with the
+// manager.
+
+typedef int64_t (*InfallibleAmountFn)();
+
+#define DECL_REGISTER_DISTINGUISHED_AMOUNT(kind, name) \
+    nsresult Register##name##DistinguishedAmount(kind##AmountFn aAmountFn);
+#define DECL_UNREGISTER_DISTINGUISHED_AMOUNT(name) \
+    nsresult Unregister##name##DistinguishedAmount();
+
+DECL_REGISTER_DISTINGUISHED_AMOUNT(Infallible, JSMainRuntimeGCHeap)
+DECL_REGISTER_DISTINGUISHED_AMOUNT(Infallible, JSMainRuntimeTemporaryPeak)
+DECL_REGISTER_DISTINGUISHED_AMOUNT(Infallible, JSMainRuntimeCompartmentsSystem)
+DECL_REGISTER_DISTINGUISHED_AMOUNT(Infallible, JSMainRuntimeCompartmentsUser)
+
+DECL_REGISTER_DISTINGUISHED_AMOUNT(Infallible, ImagesContentUsedUncompressed)
+DECL_UNREGISTER_DISTINGUISHED_AMOUNT(ImagesContentUsedUncompressed)
+
+DECL_REGISTER_DISTINGUISHED_AMOUNT(Infallible, StorageSQLite)
+DECL_UNREGISTER_DISTINGUISHED_AMOUNT(StorageSQLite)
+
+DECL_REGISTER_DISTINGUISHED_AMOUNT(Infallible, LowMemoryEventsVirtual)
+DECL_REGISTER_DISTINGUISHED_AMOUNT(Infallible, LowMemoryEventsPhysical)
+
+DECL_REGISTER_DISTINGUISHED_AMOUNT(Infallible, GhostWindows)
+
+#undef DECL_REGISTER_DISTINGUISHED_AMOUNT
+#undef DECL_UNREGISTER_DISTINGUISHED_AMOUNT
+
+// Likewise for per-tab measurement.
+
+typedef MOZ_MUST_USE nsresult (*JSSizeOfTabFn)(JSObject* aObj,
+                                               size_t* aJsObjectsSize,
+                                               size_t* aJsStringSize,
+                                               size_t* aJsPrivateSize,
+                                               size_t* aJsOtherSize);
+typedef MOZ_MUST_USE nsresult (*NonJSSizeOfTabFn)(nsPIDOMWindowOuter* aWindow,
+                                                  size_t* aDomSize,
+                                                  size_t* aStyleSize,
+                                                  size_t* aOtherSize);
+
+nsresult RegisterJSSizeOfTab(JSSizeOfTabFn aSizeOfTabFn);
+nsresult RegisterNonJSSizeOfTab(NonJSSizeOfTabFn aSizeOfTabFn);
+
+}
+
+#if defined(MOZ_DMD)
+#if !defined(MOZ_MEMORY)
+#error "MOZ_DMD requires MOZ_MEMORY"
+#endif
+
+#include "DMD.h"
+
+#define MOZ_REPORT(ptr)          mozilla::dmd::Report(ptr)
+#define MOZ_REPORT_ON_ALLOC(ptr) mozilla::dmd::ReportOnAlloc(ptr)
+
+#else
+
+#define MOZ_REPORT(ptr)
+#define MOZ_REPORT_ON_ALLOC(ptr)
+
+#endif  // defined(MOZ_DMD)
+
+// Functions generated via this macro should be used by all traversal-based
+// memory reporters.  Such functions return |moz_malloc_size_of(ptr)|;  this
+// will always be zero on some obscure platforms.
+//
+// You might be wondering why we have a macro that creates multiple functions
+// that differ only in their name, instead of a single MallocSizeOf function.
+// It's mostly to help with DMD integration, though it sometimes also helps
+// with debugging and temporary ad hoc profiling.  The function name chosen
+// doesn't matter greatly, but it's best to make it similar to the path used by
+// the relevant memory reporter(s).
+#define MOZ_DEFINE_MALLOC_SIZE_OF(fn)                                         \
+  static size_t fn(const void* aPtr)                                          \
+  {                                                                           \
+      MOZ_REPORT(aPtr);                                                       \
+      return moz_malloc_size_of(aPtr);                                        \
+  }
+
+// Functions generated by the next two macros should be used by wrapping
+// allocators that report heap blocks as soon as they are allocated and
+// unreport them as soon as they are freed.  Such allocators are used in cases
+// where we have third-party code that we cannot modify.  The two functions
+// must always be used in tandem.
+#define MOZ_DEFINE_MALLOC_SIZE_OF_ON_ALLOC(fn)                                \
+  static size_t fn(const void* aPtr)                                          \
+  {                                                                           \
+      MOZ_REPORT_ON_ALLOC(aPtr);                                              \
+      return moz_malloc_size_of(aPtr);                                        \
+  }
+#define MOZ_DEFINE_MALLOC_SIZE_OF_ON_FREE(fn)                                 \
+  static size_t fn(const void* aPtr)                                          \
+  {                                                                           \
+      return moz_malloc_size_of(aPtr);                                        \
+  }
+
+// This macro assumes the presence of appropriate |aHandleReport| and |aData|
+// variables. The (void) is there because we should always ignore the return
+// value of the callback, because callback failures aren't fatal.
+#define MOZ_COLLECT_REPORT(path, kind, units, amount, description)            \
+  (void)aHandleReport->Callback(EmptyCString(), NS_LITERAL_CSTRING(path),     \
+                                kind, units, amount,                          \
+                                NS_LITERAL_CSTRING(description), aData)
+
+%}
diff --git a/xpcom/base/nsIMessageLoop.idl b/xpcom/base/nsIMessageLoop.idl
new file mode 100644
index 000000000..b10d1c576
--- /dev/null
+++ b/xpcom/base/nsIMessageLoop.idl
@@ -0,0 +1,36 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIRunnable;
+
+/**
+ * This service allows access to the current thread's Chromium MessageLoop
+ * instance, with some extra sugar added.  If you're calling from C++, it may
+ * or may not make sense for you to use this interface.  If you're calling from
+ * JS, you don't have a choice!
+ *
+ * Right now, you can only call PostIdleTask(), and the wrath of khuey is
+ * stopping you from adding other methods.
+ *
+ * nsIMessageLoop's contractid is "@mozilla.org/message-loop;1".
+ */
+[scriptable, uuid(3E8C58E8-E52C-43E0-8E66-669CA788FF5F)]
+interface nsIMessageLoop : nsISupports
+{
+  /**
+   * Posts a task to be run when this thread's message loop is idle, or after
+   * ensureRunsAfterMS milliseconds have elapsed.  (That is, the task is
+   * guaranteed to run /eventually/.)
+   *
+   * Note that if the event loop is busy, we will hold a reference to the task
+   * until ensureRunsAfterMS milliseconds have elapsed.  Be careful when
+   * specifying long timeouts and tasks which hold references to windows or
+   * other large objects, because you can leak memory in a difficult-to-detect
+   * way!
+   */
+  void postIdleTask(in nsIRunnable task, in uint32_t ensureRunsAfterMS);
+};
diff --git a/xpcom/base/nsIMutable.idl b/xpcom/base/nsIMutable.idl
new file mode 100644
index 000000000..c5c7baab0
--- /dev/null
+++ b/xpcom/base/nsIMutable.idl
@@ -0,0 +1,22 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * nsIMutable defines an interface to be implemented by objects which
+ * can be made immutable.
+ */
+[scriptable, uuid(321578d0-03c1-4d95-8821-021ac612d18d)]
+interface nsIMutable : nsISupports
+{
+    /**
+     * Control whether or not this object can be modified.  If the flag is
+     * false, no modification is allowed.  Once the flag has been set to false,
+     * it cannot be reset back to true -- attempts to do so throw
+     * NS_ERROR_INVALID_ARG.
+     */
+    attribute boolean mutable;
+};
diff --git a/xpcom/base/nsIProgrammingLanguage.idl b/xpcom/base/nsIProgrammingLanguage.idl
new file mode 100644
index 000000000..57621168b
--- /dev/null
+++ b/xpcom/base/nsIProgrammingLanguage.idl
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * Legacy constants for specifying programming languages.
+ *
+ * JAVASCRIPT is needed to avoid breaking addons that use it in nsIClassInfo
+ * to define fields that are no longer needed.
+ *
+ * UNKNOWN and JAVASCRIPT are also used in implementations of
+ * nsIStackFrame::language.
+ */
+
+[scriptable, uuid(02ad9f22-3c98-46f3-be4e-2f5c9299e29a)]
+interface nsIProgrammingLanguage : nsISupports
+{
+    const uint32_t UNKNOWN     = 0;
+    // 1 is unused.
+    const uint32_t JAVASCRIPT  = 2;
+};
diff --git a/xpcom/base/nsISecurityConsoleMessage.idl b/xpcom/base/nsISecurityConsoleMessage.idl
new file mode 100644
index 000000000..917968d83
--- /dev/null
+++ b/xpcom/base/nsISecurityConsoleMessage.idl
@@ -0,0 +1,20 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/*
+ * Holds localization message tag and message category
+ * for security related console messages.
+ */
+[uuid(FE9FC9B6-DDE2-11E2-A8F1-0A326188709B)]
+interface nsISecurityConsoleMessage : nsISupports
+{
+  attribute AString tag;
+  attribute AString category;
+};
+
+%{ C++
+#define NS_SECURITY_CONSOLE_MESSAGE_CONTRACTID "@mozilla.org/securityconsole/message;1"
+%}
diff --git a/xpcom/base/nsISizeOf.h b/xpcom/base/nsISizeOf.h
new file mode 100644
index 000000000..35f5de44c
--- /dev/null
+++ b/xpcom/base/nsISizeOf.h
@@ -0,0 +1,35 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsISizeOf_h___
+#define nsISizeOf_h___
+
+#include "mozilla/MemoryReporting.h"
+#include "nsISupports.h"
+
+#define NS_ISIZEOF_IID \
+  {0x61d05579, 0xd7ec, 0x485c, \
+    { 0xa4, 0x0c, 0x31, 0xc7, 0x9a, 0x5c, 0xf9, 0xf3 }}
+
+class nsISizeOf : public nsISupports
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_ISIZEOF_IID)
+
+  /**
+   * Measures the size of the things pointed to by the object.
+   */
+  virtual size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const = 0;
+
+  /**
+   * Like SizeOfExcludingThis, but also includes the size of the object itself.
+   */
+  virtual size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const = 0;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsISizeOf, NS_ISIZEOF_IID)
+
+#endif /* nsISizeOf_h___ */
diff --git a/xpcom/base/nsIStatusReporter.idl b/xpcom/base/nsIStatusReporter.idl
new file mode 100644
index 000000000..9f9245f49
--- /dev/null
+++ b/xpcom/base/nsIStatusReporter.idl
@@ -0,0 +1,90 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsISimpleEnumerator;
+
+/*
+ * Status reporters show Firefox's service status.
+ */
+
+[scriptable, uuid(ffcb716c-deeb-44ea-9d9d-ab25dc6980a8)]
+interface nsIStatusReporter : nsISupports
+{
+  readonly attribute ACString name;
+  /*
+   * The name of the process containing this reporter.  Each reporter initially
+   * has "" in this field, indicating that it applies to the current process.
+   */
+  readonly attribute ACString process;
+  /*
+   * A human-readable status description.
+   */
+  readonly attribute AUTF8String description;
+};
+
+[scriptable, uuid(fd531273-3319-4fcd-90f2-9f53876c3828)]
+interface nsIStatusReporterManager : nsISupports
+{
+
+  /*
+   * Return an enumerator of nsIStatusReporters that are currently registered.
+   */
+  nsISimpleEnumerator enumerateReporters();
+
+  /*
+   * Register the given nsIStatusReporter.  After a reporter is registered,
+   * it will be available via enumerateReporters().  The Manager service
+   * will hold a strong reference to the given reporter.
+   */
+  void registerReporter(in nsIStatusReporter reporter);
+
+  /*
+   * Unregister the given status reporter.
+   */
+  void unregisterReporter(in nsIStatusReporter reporter);
+
+ /*
+  * Initialize.
+  */
+  void init();
+
+  /*
+   * Dump service status as a json file
+   */
+  void dumpReports();
+};
+
+%{C++
+
+/*
+ * Note that this defaults 'process' to "", which is usually what's desired.
+ */
+#define NS_STATUS_REPORTER_IMPLEMENT(_classname, _name, _desc_Function)       \
+    class StatusReporter_##_classname final : public nsIStatusReporter {      \
+      ~StatusReporter_##_classname() {}                                       \
+    public:                                                                   \
+      NS_DECL_ISUPPORTS                                                       \
+      NS_IMETHOD GetName(nsACString &name) override                           \
+        { name.AssignLiteral(_name); return NS_OK; }                          \
+      NS_IMETHOD GetProcess(nsACString &process) override                     \
+        { process.Truncate(); return NS_OK; }                                 \
+      NS_IMETHOD GetDescription(nsACString &desc) override                    \
+        { _desc_Function(desc); return NS_OK; }                               \
+    };                                                                        \
+    NS_IMPL_ISUPPORTS(StatusReporter_##_classname, nsIStatusReporter)
+
+#define NS_STATUS_REPORTER_NAME(_classname)  StatusReporter_##_classname
+
+nsresult NS_RegisterStatusReporter(nsIStatusReporter *reporter);
+nsresult NS_UnregisterStatusReporter(nsIStatusReporter *reporter);
+nsresult NS_DumpStatusReporter();
+
+#define NS_STATUS_REPORTER_MANAGER_CID \
+{ 0xe8eb4e7e, 0xf2cf, 0x45e5, \
+{ 0xb8, 0xa4, 0x6a, 0x0f, 0x50, 0x18, 0x84, 0x63 } }
+%}
diff --git a/xpcom/base/nsISupports.idl b/xpcom/base/nsISupports.idl
new file mode 100644
index 000000000..45ea44ecb
--- /dev/null
+++ b/xpcom/base/nsISupports.idl
@@ -0,0 +1,44 @@
+/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+  
+/**
+ * The mother of all xpcom interfaces.
+ */
+
+/* In order to get both the right typelib and the right header we force
+*  the 'real' output from xpidl to be commented out in the generated header
+*  and includes a copy of the original nsISupports.h. This is all just to deal 
+*  with the Mac specific ": public __comobject" thing.
+*/
+
+#include "nsrootidl.idl"
+
+%{C++
+/* 
+ * Start commenting out the C++ versions of the below in the output header
+ */
+#if 0
+%}
+
+[scriptable, uuid(00000000-0000-0000-c000-000000000046)]
+interface nsISupports {
+  void QueryInterface(in nsIIDRef uuid, 
+                      [iid_is(uuid),retval] out nsQIResult result);
+  [noscript, notxpcom] nsrefcnt AddRef();
+  [noscript, notxpcom] nsrefcnt Release();
+};
+
+%{C++
+/* 
+ * End commenting out the C++ versions of the above in the output header
+ */
+#endif
+%}
+
+
+%{C++
+#include "nsISupportsBase.h"
+#include "nsISupportsUtils.h"
+%}
diff --git a/xpcom/base/nsISupportsBase.h b/xpcom/base/nsISupportsBase.h
new file mode 100644
index 000000000..bf5518b81
--- /dev/null
+++ b/xpcom/base/nsISupportsBase.h
@@ -0,0 +1,85 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+// IWYU pragma: private, include "nsISupports.h"
+
+#ifndef nsISupportsBase_h__
+#define nsISupportsBase_h__
+
+#ifndef nscore_h___
+#include "nscore.h"
+#endif
+
+#ifndef nsID_h__
+#include "nsID.h"
+#endif
+
+
+/*@{*/
+/**
+ * IID for the nsISupports interface
+ * {00000000-0000-0000-c000-000000000046}
+ *
+ * To maintain binary compatibility with COM's IUnknown, we define the IID
+ * of nsISupports to be the same as that of COM's IUnknown.
+ */
+#define NS_ISUPPORTS_IID                                                      \
+  { 0x00000000, 0x0000, 0x0000,                                               \
+    {0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x46} }
+
+/**
+ * Basic component object model interface. Objects which implement
+ * this interface support runtime interface discovery (QueryInterface)
+ * and a reference counted memory model (AddRef/Release). This is
+ * modelled after the win32 IUnknown API.
+ */
+class NS_NO_VTABLE nsISupports
+{
+public:
+
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_ISUPPORTS_IID)
+
+  /**
+   * @name Methods
+   */
+
+  //@{
+  /**
+   * A run time mechanism for interface discovery.
+   * @param aIID [in] A requested interface IID
+   * @param aInstancePtr [out] A pointer to an interface pointer to
+   * receive the result.
+   * @return <b>NS_OK</b> if the interface is supported by the associated
+   * instance, <b>NS_NOINTERFACE</b> if it is not.
+   *
+   * aInstancePtr must not be null.
+   */
+  NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr) = 0;
+  /**
+   * Increases the reference count for this interface.
+   * The associated instance will not be deleted unless
+   * the reference count is returned to zero.
+   *
+   * @return The resulting reference count.
+   */
+  NS_IMETHOD_(MozExternalRefCountType) AddRef(void) = 0;
+
+  /**
+   * Decreases the reference count for this interface.
+   * Generally, if the reference count returns to zero,
+   * the associated instance is deleted.
+   *
+   * @return The resulting reference count.
+   */
+  NS_IMETHOD_(MozExternalRefCountType) Release(void) = 0;
+
+  //@}
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsISupports, NS_ISUPPORTS_IID)
+
+/*@}*/
+
+#endif
diff --git a/xpcom/base/nsIUUIDGenerator.idl b/xpcom/base/nsIUUIDGenerator.idl
new file mode 100644
index 000000000..8715ed622
--- /dev/null
+++ b/xpcom/base/nsIUUIDGenerator.idl
@@ -0,0 +1,39 @@
+/* -*- Mode: C++; tab-width: 50; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+[ptr] native nsNonConstIDPtr(nsID);
+
+/**
+ * nsIUUIDGenerator is implemented by a service that can generate
+ * universally unique identifiers, ideally using any platform-native
+ * method for generating UUIDs.
+ */
+[scriptable, uuid(138ad1b2-c694-41cc-b201-333ce936d8b8)]
+interface nsIUUIDGenerator : nsISupports
+{
+  /**
+   * Obtains a new UUID using appropriate platform-specific methods to
+   * obtain a nsID that can be considered to be globally unique.
+   *
+   * @returns an nsID filled in with a new UUID.
+   *
+   * @throws NS_ERROR_FAILURE if a UUID cannot be generated (e.g. if
+   * an underlying source of randomness is not available)
+   */
+  nsIDPtr generateUUID();
+
+  /**
+   * Obtain a new UUID like the generateUUID method, but place it in
+   * the provided nsID pointer instead of allocating a new nsID.
+   *
+   * @param id an existing nsID pointer where the UUID will be stored.
+   *
+   * @throws NS_ERROR_FAILURE if a UUID cannot be generated (e.g. if
+   * an underlying source of randomness is not available)
+   */
+  [noscript] void generateUUIDInPlace(in nsNonConstIDPtr id);
+};
diff --git a/xpcom/base/nsIVersionComparator.idl b/xpcom/base/nsIVersionComparator.idl
new file mode 100644
index 000000000..1a33cb74e
--- /dev/null
+++ b/xpcom/base/nsIVersionComparator.idl
@@ -0,0 +1,49 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * Version strings are dot-separated sequences of version-parts.
+ *
+ * A version-part consists of up to four parts, all of which are optional:
+ *
+ * <number-a><string-b><number-c><string-d (everything else)>
+ *
+ * A version-part may also consist of a single asterisk "*" which indicates
+ * "infinity".
+ *
+ * Numbers are base-10, and are zero if left out.
+ * Strings are compared bytewise.
+ *
+ * For additional backwards compatibility, if "string-b" is "+" then
+ * "number-a" is incremented by 1 and "string-b" becomes "pre".
+ *
+ * 1.0pre1
+ * < 1.0pre2  
+ *   < 1.0 == 1.0.0 == 1.0.0.0
+ *     < 1.1pre == 1.1pre0 == 1.0+
+ *       < 1.1pre1a
+ *         < 1.1pre1
+ *           < 1.1pre10a
+ *             < 1.1pre10
+ *
+ * Although not required by this interface, it is recommended that
+ * numbers remain within the limits of a signed char, i.e. -127 to 128.
+ */
+[scriptable, uuid(e6cd620a-edbb-41d2-9e42-9a2ffc8107f3)]
+interface nsIVersionComparator : nsISupports
+{
+  /**
+   * Compare two version strings
+   * @param   A   The first version
+   * @param   B   The second version
+   * @returns < 0 if A < B
+   *          = 0 if A == B
+   *          > 0 if A > B
+   */
+  long compare(in ACString A, in ACString B);
+};
+
diff --git a/xpcom/base/nsIWeakReference.idl b/xpcom/base/nsIWeakReference.idl
new file mode 100644
index 000000000..73390b15f
--- /dev/null
+++ b/xpcom/base/nsIWeakReference.idl
@@ -0,0 +1,74 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+%{C++
+#include "mozilla/MemoryReporting.h"
+%}
+
+/**
+ * An instance of |nsIWeakReference| is a proxy object that cooperates with
+ * its referent to give clients a non-owning, non-dangling reference.  Clients
+ * own the proxy, and should generally manage it with an |nsCOMPtr| (see the
+ * type |nsWeakPtr| for a |typedef| name that stands out) as they would any
+ * other XPCOM object.  The |QueryReferent| member function provides a
+ * (hopefully short-lived) owning reference on demand, through which clients
+ * can get useful access to the referent, while it still exists.
+ *
+ * @version 1.0
+ * @see nsISupportsWeakReference
+ * @see nsWeakReference
+ * @see nsWeakPtr
+ */
+[scriptable, uuid(9188bc85-f92e-11d2-81ef-0060083a0bcf)]
+interface nsIWeakReference : nsISupports
+  {
+    /**
+     * |QueryReferent| queries the referent, if it exists, and like |QueryInterface|, produces
+     * an owning reference to the desired interface.  It is designed to look and act exactly
+     * like (a proxied) |QueryInterface|.  Don't hold on to the produced interface permanently;
+     * that would defeat the purpose of using a non-owning |nsIWeakReference| in the first place.
+     */
+    void QueryReferent( in nsIIDRef uuid, [iid_is(uuid), retval] out nsQIResult result );
+
+%{C++
+    virtual size_t SizeOfOnlyThis(mozilla::MallocSizeOf aMallocSizeOf) const = 0;
+%}
+  };
+
+
+/**
+ * |nsISupportsWeakReference| is a factory interface which produces appropriate
+ * instances of |nsIWeakReference|.  Weak references in this scheme can only be
+ * produced for objects that implement this interface.
+ *
+ * @version 1.0
+ * @see nsIWeakReference
+ * @see nsSupportsWeakReference
+ */
+[scriptable, uuid(9188bc86-f92e-11d2-81ef-0060083a0bcf)]
+interface nsISupportsWeakReference : nsISupports
+  {
+    /**
+     * |GetWeakReference| produces an appropriate instance of |nsIWeakReference|.
+     * As with all good XPCOM `getters', you own the resulting interface and should
+     * manage it with an |nsCOMPtr|.
+     *
+     * @see nsIWeakReference
+     * @see nsWeakPtr
+     * @see nsCOMPtr
+     */
+    nsIWeakReference GetWeakReference();
+  };
+
+
+%{C++
+#ifdef MOZILLA_INTERNAL_API
+#include "nsIWeakReferenceUtils.h"
+#endif
+%}
+
diff --git a/xpcom/base/nsInterfaceRequestorAgg.cpp b/xpcom/base/nsInterfaceRequestorAgg.cpp
new file mode 100644
index 000000000..7e5cd83da
--- /dev/null
+++ b/xpcom/base/nsInterfaceRequestorAgg.cpp
@@ -0,0 +1,86 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsInterfaceRequestorAgg.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsCOMPtr.h"
+#include "mozilla/Attributes.h"
+#include "nsThreadUtils.h"
+#include "nsProxyRelease.h"
+
+class nsInterfaceRequestorAgg final : public nsIInterfaceRequestor
+{
+public:
+  // XXX This needs to support threadsafe refcounting until we fix bug 243591.
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIINTERFACEREQUESTOR
+
+  nsInterfaceRequestorAgg(nsIInterfaceRequestor* aFirst,
+                          nsIInterfaceRequestor* aSecond,
+                          nsIEventTarget* aConsumerTarget = nullptr)
+    : mFirst(aFirst)
+    , mSecond(aSecond)
+    , mConsumerTarget(aConsumerTarget)
+  {
+    if (!mConsumerTarget) {
+      mConsumerTarget = NS_GetCurrentThread();
+    }
+  }
+
+private:
+  ~nsInterfaceRequestorAgg();
+
+  nsCOMPtr<nsIInterfaceRequestor> mFirst, mSecond;
+  nsCOMPtr<nsIEventTarget> mConsumerTarget;
+};
+
+NS_IMPL_ISUPPORTS(nsInterfaceRequestorAgg, nsIInterfaceRequestor)
+
+NS_IMETHODIMP
+nsInterfaceRequestorAgg::GetInterface(const nsIID& aIID, void** aResult)
+{
+  nsresult rv = NS_ERROR_NO_INTERFACE;
+  if (mFirst) {
+    rv = mFirst->GetInterface(aIID, aResult);
+  }
+  if (mSecond && NS_FAILED(rv)) {
+    rv = mSecond->GetInterface(aIID, aResult);
+  }
+  return rv;
+}
+
+nsInterfaceRequestorAgg::~nsInterfaceRequestorAgg()
+{
+  NS_ProxyRelease(mConsumerTarget, mFirst.forget());
+  NS_ProxyRelease(mConsumerTarget, mSecond.forget());
+}
+
+nsresult
+NS_NewInterfaceRequestorAggregation(nsIInterfaceRequestor* aFirst,
+                                    nsIInterfaceRequestor* aSecond,
+                                    nsIInterfaceRequestor** aResult)
+{
+  *aResult = new nsInterfaceRequestorAgg(aFirst, aSecond);
+  if (!*aResult) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  NS_ADDREF(*aResult);
+  return NS_OK;
+}
+
+nsresult
+NS_NewInterfaceRequestorAggregation(nsIInterfaceRequestor* aFirst,
+                                    nsIInterfaceRequestor* aSecond,
+                                    nsIEventTarget* aTarget,
+                                    nsIInterfaceRequestor** aResult)
+{
+  *aResult = new nsInterfaceRequestorAgg(aFirst, aSecond, aTarget);
+  if (!*aResult) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  NS_ADDREF(*aResult);
+  return NS_OK;
+}
diff --git a/xpcom/base/nsInterfaceRequestorAgg.h b/xpcom/base/nsInterfaceRequestorAgg.h
new file mode 100644
index 000000000..62b4f61f9
--- /dev/null
+++ b/xpcom/base/nsInterfaceRequestorAgg.h
@@ -0,0 +1,38 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsInterfaceRequestorAgg_h__
+#define nsInterfaceRequestorAgg_h__
+
+#include "nsError.h"
+
+class nsIEventTarget;
+class nsIInterfaceRequestor;
+
+/**
+ * This function returns an instance of nsIInterfaceRequestor that aggregates
+ * two nsIInterfaceRequestor instances.  Its GetInterface method queries
+ * aFirst for the requested interface and will query aSecond only if aFirst
+ * failed to supply the requested interface.  Both aFirst and aSecond may
+ * be null, and will be released on the main thread when the aggregator is
+ * destroyed.
+ */
+extern nsresult
+NS_NewInterfaceRequestorAggregation(nsIInterfaceRequestor* aFirst,
+                                    nsIInterfaceRequestor* aSecond,
+                                    nsIInterfaceRequestor** aResult);
+
+/**
+ * Like the previous method, but aFirst and aSecond will be released on the
+ * provided target thread.
+ */
+extern nsresult
+NS_NewInterfaceRequestorAggregation(nsIInterfaceRequestor* aFirst,
+                                    nsIInterfaceRequestor* aSecond,
+                                    nsIEventTarget* aTarget,
+                                    nsIInterfaceRequestor** aResult);
+
+#endif // !defined( nsInterfaceRequestorAgg_h__ )
diff --git a/xpcom/base/nsMacUtilsImpl.cpp b/xpcom/base/nsMacUtilsImpl.cpp
new file mode 100644
index 000000000..e2706047a
--- /dev/null
+++ b/xpcom/base/nsMacUtilsImpl.cpp
@@ -0,0 +1,147 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsMacUtilsImpl.h"
+
+#include <CoreFoundation/CoreFoundation.h>
+
+NS_IMPL_ISUPPORTS(nsMacUtilsImpl, nsIMacUtils)
+
+nsresult
+nsMacUtilsImpl::GetArchString(nsAString& aArchString)
+{
+  if (!mBinaryArchs.IsEmpty()) {
+    aArchString.Assign(mBinaryArchs);
+    return NS_OK;
+  }
+
+  aArchString.Truncate();
+
+  bool foundPPC = false,
+       foundX86 = false,
+       foundPPC64 = false,
+       foundX86_64 = false;
+
+  CFBundleRef mainBundle = ::CFBundleGetMainBundle();
+  if (!mainBundle) {
+    return NS_ERROR_FAILURE;
+  }
+
+  CFArrayRef archList = ::CFBundleCopyExecutableArchitectures(mainBundle);
+  if (!archList) {
+    return NS_ERROR_FAILURE;
+  }
+
+  CFIndex archCount = ::CFArrayGetCount(archList);
+  for (CFIndex i = 0; i < archCount; i++) {
+    CFNumberRef arch =
+      static_cast<CFNumberRef>(::CFArrayGetValueAtIndex(archList, i));
+
+    int archInt = 0;
+    if (!::CFNumberGetValue(arch, kCFNumberIntType, &archInt)) {
+      ::CFRelease(archList);
+      return NS_ERROR_FAILURE;
+    }
+
+    if (archInt == kCFBundleExecutableArchitecturePPC) {
+      foundPPC = true;
+    } else if (archInt == kCFBundleExecutableArchitectureI386) {
+      foundX86 = true;
+    } else if (archInt == kCFBundleExecutableArchitecturePPC64) {
+      foundPPC64 = true;
+    } else if (archInt == kCFBundleExecutableArchitectureX86_64) {
+      foundX86_64 = true;
+    }
+  }
+
+  ::CFRelease(archList);
+
+  // The order in the string must always be the same so
+  // don't do this in the loop.
+  if (foundPPC) {
+    mBinaryArchs.AppendLiteral("ppc");
+  }
+
+  if (foundX86) {
+    if (!mBinaryArchs.IsEmpty()) {
+      mBinaryArchs.Append('-');
+    }
+    mBinaryArchs.AppendLiteral("i386");
+  }
+
+  if (foundPPC64) {
+    if (!mBinaryArchs.IsEmpty()) {
+      mBinaryArchs.Append('-');
+    }
+    mBinaryArchs.AppendLiteral("ppc64");
+  }
+
+  if (foundX86_64) {
+    if (!mBinaryArchs.IsEmpty()) {
+      mBinaryArchs.Append('-');
+    }
+    mBinaryArchs.AppendLiteral("x86_64");
+  }
+
+  aArchString.Assign(mBinaryArchs);
+
+  return (aArchString.IsEmpty() ? NS_ERROR_FAILURE : NS_OK);
+}
+
+NS_IMETHODIMP
+nsMacUtilsImpl::GetIsUniversalBinary(bool* aIsUniversalBinary)
+{
+  if (NS_WARN_IF(!aIsUniversalBinary)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  *aIsUniversalBinary = false;
+
+  nsAutoString archString;
+  nsresult rv = GetArchString(archString);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // The delimiter char in the arch string is '-', so if that character
+  // is in the string we know we have multiple architectures.
+  *aIsUniversalBinary = (archString.Find("-") > -1);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMacUtilsImpl::GetArchitecturesInBinary(nsAString& aArchString)
+{
+  return GetArchString(aArchString);
+}
+
+// True when running under binary translation (Rosetta).
+NS_IMETHODIMP
+nsMacUtilsImpl::GetIsTranslated(bool* aIsTranslated)
+{
+#ifdef __ppc__
+  static bool    sInitialized = false;
+
+  // Initialize sIsNative to 1.  If the sysctl fails because it doesn't
+  // exist, then translation is not possible, so the process must not be
+  // running translated.
+  static int32_t sIsNative = 1;
+
+  if (!sInitialized) {
+    size_t sz = sizeof(sIsNative);
+    sysctlbyname("sysctl.proc_native", &sIsNative, &sz, nullptr, 0);
+    sInitialized = true;
+  }
+
+  *aIsTranslated = !sIsNative;
+#else
+  // Translation only exists for ppc code.  Other architectures aren't
+  // translated.
+  *aIsTranslated = false;
+#endif
+
+  return NS_OK;
+}
diff --git a/xpcom/base/nsMacUtilsImpl.h b/xpcom/base/nsMacUtilsImpl.h
new file mode 100644
index 000000000..4a480ffe5
--- /dev/null
+++ b/xpcom/base/nsMacUtilsImpl.h
@@ -0,0 +1,42 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMacUtilsImpl_h___
+#define nsMacUtilsImpl_h___
+
+#include "nsIMacUtils.h"
+#include "nsString.h"
+#include "mozilla/Attributes.h"
+
+class nsMacUtilsImpl final : public nsIMacUtils
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIMACUTILS
+
+  nsMacUtilsImpl()
+  {
+  }
+
+private:
+  ~nsMacUtilsImpl()
+  {
+  }
+
+  nsresult GetArchString(nsAString& aArchString);
+
+  // A string containing a "-" delimited list of architectures
+  // in our binary.
+  nsString mBinaryArchs;
+};
+
+// Global singleton service
+// 697BD3FD-43E5-41CE-AD5E-C339175C0818
+#define NS_MACUTILSIMPL_CID \
+ {0x697BD3FD, 0x43E5, 0x41CE, {0xAD, 0x5E, 0xC3, 0x39, 0x17, 0x5C, 0x08, 0x18}}
+#define NS_MACUTILSIMPL_CONTRACTID "@mozilla.org/xpcom/mac-utils;1"
+
+#endif /* nsMacUtilsImpl_h___ */
diff --git a/xpcom/base/nsMemoryImpl.cpp b/xpcom/base/nsMemoryImpl.cpp
new file mode 100644
index 000000000..1d1576fbd
--- /dev/null
+++ b/xpcom/base/nsMemoryImpl.cpp
@@ -0,0 +1,184 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsMemoryImpl.h"
+#include "nsThreadUtils.h"
+
+#include "nsIObserver.h"
+#include "nsIObserverService.h"
+#include "nsISimpleEnumerator.h"
+
+#include "nsCOMPtr.h"
+#include "mozilla/Services.h"
+
+#ifdef ANDROID
+#include <stdio.h>
+
+// Minimum memory threshold for a device to be considered
+// a low memory platform. This value has be in sync with
+// Java's equivalent threshold, defined in
+// mobile/android/base/util/HardwareUtils.java
+#define LOW_MEMORY_THRESHOLD_KB (384 * 1024)
+#endif
+
+static nsMemoryImpl sGlobalMemory;
+
+NS_IMPL_QUERY_INTERFACE(nsMemoryImpl, nsIMemory)
+
+NS_IMETHODIMP
+nsMemoryImpl::HeapMinimize(bool aImmediate)
+{
+  return FlushMemory(u"heap-minimize", aImmediate);
+}
+
+NS_IMETHODIMP
+nsMemoryImpl::IsLowMemoryPlatform(bool* aResult)
+{
+#ifdef ANDROID
+  static int sLowMemory = -1; // initialize to unknown, lazily evaluate to 0 or 1
+  if (sLowMemory == -1) {
+    sLowMemory = 0; // assume "not low memory" in case file operations fail
+    *aResult = false;
+
+    // check if MemTotal from /proc/meminfo is less than LOW_MEMORY_THRESHOLD_KB
+    FILE* fd = fopen("/proc/meminfo", "r");
+    if (!fd) {
+      return NS_OK;
+    }
+    uint64_t mem = 0;
+    int rv = fscanf(fd, "MemTotal: %llu kB", &mem);
+    if (fclose(fd)) {
+      return NS_OK;
+    }
+    if (rv != 1) {
+      return NS_OK;
+    }
+    sLowMemory = (mem < LOW_MEMORY_THRESHOLD_KB) ? 1 : 0;
+  }
+  *aResult = (sLowMemory == 1);
+#else
+  *aResult = false;
+#endif
+  return NS_OK;
+}
+
+/*static*/ nsresult
+nsMemoryImpl::Create(nsISupports* aOuter, const nsIID& aIID, void** aResult)
+{
+  if (NS_WARN_IF(aOuter)) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+  return sGlobalMemory.QueryInterface(aIID, aResult);
+}
+
+nsresult
+nsMemoryImpl::FlushMemory(const char16_t* aReason, bool aImmediate)
+{
+  nsresult rv = NS_OK;
+
+  if (aImmediate) {
+    // They've asked us to run the flusher *immediately*. We've
+    // got to be on the UI main thread for us to be able to do
+    // that...are we?
+    if (!NS_IsMainThread()) {
+      NS_ERROR("can't synchronously flush memory: not on UI thread");
+      return NS_ERROR_FAILURE;
+    }
+  }
+
+  bool lastVal = sIsFlushing.exchange(true);
+  if (lastVal) {
+    return NS_OK;
+  }
+
+  PRIntervalTime now = PR_IntervalNow();
+
+  // Run the flushers immediately if we can; otherwise, proxy to the
+  // UI thread an run 'em asynchronously.
+  if (aImmediate) {
+    rv = RunFlushers(aReason);
+  } else {
+    // Don't broadcast more than once every 1000ms to avoid being noisy
+    if (PR_IntervalToMicroseconds(now - sLastFlushTime) > 1000) {
+      sFlushEvent.mReason = aReason;
+      rv = NS_DispatchToMainThread(&sFlushEvent);
+    }
+  }
+
+  sLastFlushTime = now;
+  return rv;
+}
+
+nsresult
+nsMemoryImpl::RunFlushers(const char16_t* aReason)
+{
+  nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
+  if (os) {
+
+    // Instead of:
+    //  os->NotifyObservers(this, "memory-pressure", aReason);
+    // we are going to do this manually to see who/what is
+    // deallocating.
+
+    nsCOMPtr<nsISimpleEnumerator> e;
+    os->EnumerateObservers("memory-pressure", getter_AddRefs(e));
+
+    if (e) {
+      nsCOMPtr<nsIObserver> observer;
+      bool loop = true;
+
+      while (NS_SUCCEEDED(e->HasMoreElements(&loop)) && loop) {
+        nsCOMPtr<nsISupports> supports;
+        e->GetNext(getter_AddRefs(supports));
+
+        if (!supports) {
+          continue;
+        }
+
+        observer = do_QueryInterface(supports);
+        observer->Observe(observer, "memory-pressure", aReason);
+      }
+    }
+  }
+
+  sIsFlushing = false;
+  return NS_OK;
+}
+
+// XXX need NS_IMPL_STATIC_ADDREF/RELEASE
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsMemoryImpl::FlushEvent::AddRef()
+{
+  return 2;
+}
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsMemoryImpl::FlushEvent::Release()
+{
+  return 1;
+}
+NS_IMPL_QUERY_INTERFACE(nsMemoryImpl::FlushEvent, nsIRunnable)
+
+NS_IMETHODIMP
+nsMemoryImpl::FlushEvent::Run()
+{
+  sGlobalMemory.RunFlushers(mReason);
+  return NS_OK;
+}
+
+mozilla::Atomic<bool>
+nsMemoryImpl::sIsFlushing;
+
+PRIntervalTime
+nsMemoryImpl::sLastFlushTime = 0;
+
+nsMemoryImpl::FlushEvent
+nsMemoryImpl::sFlushEvent;
+
+nsresult
+NS_GetMemoryManager(nsIMemory** aResult)
+{
+  return sGlobalMemory.QueryInterface(NS_GET_IID(nsIMemory), (void**)aResult);
+}
diff --git a/xpcom/base/nsMemoryImpl.h b/xpcom/base/nsMemoryImpl.h
new file mode 100644
index 000000000..9e2d46d38
--- /dev/null
+++ b/xpcom/base/nsMemoryImpl.h
@@ -0,0 +1,55 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMemoryImpl_h__
+#define nsMemoryImpl_h__
+
+#include "mozilla/Atomics.h"
+
+#include "nsIMemory.h"
+#include "nsIRunnable.h"
+
+// nsMemoryImpl is a static object. We can do this because it doesn't have
+// a constructor/destructor or any instance members. Please don't add
+// instance member variables, only static member variables.
+
+class nsMemoryImpl : public nsIMemory
+{
+public:
+  // We don't use the generic macros because we are a special static object
+  NS_IMETHOD QueryInterface(REFNSIID aIID, void** aResult) override;
+  NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override
+  {
+    return 1;
+  }
+  NS_IMETHOD_(MozExternalRefCountType) Release(void) override
+  {
+    return 1;
+  }
+
+  NS_DECL_NSIMEMORY
+
+  static nsresult Create(nsISupports* aOuter,
+                         const nsIID& aIID, void** aResult);
+
+  nsresult FlushMemory(const char16_t* aReason, bool aImmediate);
+  nsresult RunFlushers(const char16_t* aReason);
+
+protected:
+  struct FlushEvent : public nsIRunnable
+  {
+    constexpr FlushEvent() : mReason(nullptr) {}
+    NS_DECL_ISUPPORTS_INHERITED
+    NS_DECL_NSIRUNNABLE
+    const char16_t* mReason;
+  };
+
+  static mozilla::Atomic<bool> sIsFlushing;
+  static FlushEvent sFlushEvent;
+  static PRIntervalTime sLastFlushTime;
+};
+
+#endif // nsMemoryImpl_h__
diff --git a/xpcom/base/nsMemoryInfoDumper.cpp b/xpcom/base/nsMemoryInfoDumper.cpp
new file mode 100644
index 000000000..06453b126
--- /dev/null
+++ b/xpcom/base/nsMemoryInfoDumper.cpp
@@ -0,0 +1,830 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/JSONWriter.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/nsMemoryInfoDumper.h"
+#include "mozilla/DebugOnly.h"
+#include "nsDumpUtils.h"
+
+#include "mozilla/Unused.h"
+#include "mozilla/dom/ContentParent.h"
+#include "mozilla/dom/ContentChild.h"
+#include "nsIConsoleService.h"
+#include "nsCycleCollector.h"
+#include "nsICycleCollectorListener.h"
+#include "nsIMemoryReporter.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsGZFileWriter.h"
+#include "nsJSEnvironment.h"
+#include "nsPrintfCString.h"
+#include "nsISimpleEnumerator.h"
+#include "nsServiceManagerUtils.h"
+#include "nsIFile.h"
+
+#ifdef XP_WIN
+#include <process.h>
+#ifndef getpid
+#define getpid _getpid
+#endif
+#else
+#include <unistd.h>
+#endif
+
+#ifdef XP_UNIX
+#define MOZ_SUPPORTS_FIFO 1
+#endif
+
+#if defined(XP_LINUX) || defined(__FreeBSD__)
+#define MOZ_SUPPORTS_RT_SIGNALS 1
+#endif
+
+#if defined(MOZ_SUPPORTS_RT_SIGNALS)
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#endif
+
+#if defined(MOZ_SUPPORTS_FIFO)
+#include "mozilla/Preferences.h"
+#endif
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+namespace {
+
+class DumpMemoryInfoToTempDirRunnable : public Runnable
+{
+public:
+  DumpMemoryInfoToTempDirRunnable(const nsAString& aIdentifier,
+                                  bool aAnonymize, bool aMinimizeMemoryUsage)
+    : mIdentifier(aIdentifier)
+    , mAnonymize(aAnonymize)
+    , mMinimizeMemoryUsage(aMinimizeMemoryUsage)
+  {
+  }
+
+  NS_IMETHOD Run() override
+  {
+    nsCOMPtr<nsIMemoryInfoDumper> dumper =
+      do_GetService("@mozilla.org/memory-info-dumper;1");
+    dumper->DumpMemoryInfoToTempDir(mIdentifier, mAnonymize,
+                                    mMinimizeMemoryUsage);
+    return NS_OK;
+  }
+
+private:
+  const nsString mIdentifier;
+  const bool mAnonymize;
+  const bool mMinimizeMemoryUsage;
+};
+
+class GCAndCCLogDumpRunnable final
+  : public Runnable
+  , public nsIDumpGCAndCCLogsCallback
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+
+  GCAndCCLogDumpRunnable(const nsAString& aIdentifier,
+                         bool aDumpAllTraces,
+                         bool aDumpChildProcesses)
+    : mIdentifier(aIdentifier)
+    , mDumpAllTraces(aDumpAllTraces)
+    , mDumpChildProcesses(aDumpChildProcesses)
+  {
+  }
+
+  NS_IMETHOD Run() override
+  {
+    nsCOMPtr<nsIMemoryInfoDumper> dumper =
+      do_GetService("@mozilla.org/memory-info-dumper;1");
+
+    dumper->DumpGCAndCCLogsToFile(mIdentifier, mDumpAllTraces,
+                                  mDumpChildProcesses, this);
+    return NS_OK;
+  }
+
+  NS_IMETHOD OnDump(nsIFile* aGCLog, nsIFile* aCCLog, bool aIsParent) override
+  {
+    return NS_OK;
+  }
+
+  NS_IMETHOD OnFinish() override
+  {
+    return NS_OK;
+  }
+
+private:
+  ~GCAndCCLogDumpRunnable() {}
+
+  const nsString mIdentifier;
+  const bool mDumpAllTraces;
+  const bool mDumpChildProcesses;
+};
+
+NS_IMPL_ISUPPORTS_INHERITED(GCAndCCLogDumpRunnable, Runnable,
+                            nsIDumpGCAndCCLogsCallback)
+
+} // namespace
+
+#if defined(MOZ_SUPPORTS_RT_SIGNALS) // {
+namespace {
+
+/*
+ * The following code supports dumping about:memory upon receiving a signal.
+ *
+ * We listen for the following signals:
+ *
+ *  - SIGRTMIN:     Dump our memory reporters (and those of our child
+ *                  processes),
+ *  - SIGRTMIN + 1: Dump our memory reporters (and those of our child
+ *                  processes) after minimizing memory usage, and
+ *  - SIGRTMIN + 2: Dump the GC and CC logs in this and our child processes.
+ *
+ * When we receive one of these signals, we write the signal number to a pipe.
+ * The IO thread then notices that the pipe has been written to, and kicks off
+ * the appropriate task on the main thread.
+ *
+ * This scheme is similar to using signalfd(), except it's portable and it
+ * doesn't require the use of sigprocmask, which is problematic because it
+ * masks signals received by child processes.
+ *
+ * In theory, we could use Chromium's MessageLoopForIO::CatchSignal() for this.
+ * But that uses libevent, which does not handle the realtime signals (bug
+ * 794074).
+ */
+
+// It turns out that at least on some systems, SIGRTMIN is not a compile-time
+// constant, so these have to be set at runtime.
+static uint8_t sDumpAboutMemorySignum;         // SIGRTMIN
+static uint8_t sDumpAboutMemoryAfterMMUSignum; // SIGRTMIN + 1
+static uint8_t sGCAndCCDumpSignum;             // SIGRTMIN + 2
+
+void doMemoryReport(const uint8_t aRecvSig)
+{
+  // Dump our memory reports (but run this on the main thread!).
+  bool minimize = aRecvSig == sDumpAboutMemoryAfterMMUSignum;
+  LOG("SignalWatcher(sig %d) dispatching memory report runnable.", aRecvSig);
+  RefPtr<DumpMemoryInfoToTempDirRunnable> runnable =
+    new DumpMemoryInfoToTempDirRunnable(/* identifier = */ EmptyString(),
+                                        /* anonymize = */ false,
+                                        minimize);
+  NS_DispatchToMainThread(runnable);
+}
+
+void doGCCCDump(const uint8_t aRecvSig)
+{
+  LOG("SignalWatcher(sig %d) dispatching GC/CC log runnable.", aRecvSig);
+  // Dump GC and CC logs (from the main thread).
+  RefPtr<GCAndCCLogDumpRunnable> runnable =
+    new GCAndCCLogDumpRunnable(/* identifier = */ EmptyString(),
+                               /* allTraces = */ true,
+                               /* dumpChildProcesses = */ true);
+  NS_DispatchToMainThread(runnable);
+}
+
+} // namespace
+#endif // MOZ_SUPPORTS_RT_SIGNALS }
+
+#if defined(MOZ_SUPPORTS_FIFO) // {
+namespace {
+
+void
+doMemoryReport(const nsCString& aInputStr)
+{
+  bool minimize = aInputStr.EqualsLiteral("minimize memory report");
+  LOG("FifoWatcher(command:%s) dispatching memory report runnable.",
+      aInputStr.get());
+  RefPtr<DumpMemoryInfoToTempDirRunnable> runnable =
+    new DumpMemoryInfoToTempDirRunnable(/* identifier = */ EmptyString(),
+                                        /* anonymize = */ false,
+                                        minimize);
+  NS_DispatchToMainThread(runnable);
+}
+
+void
+doGCCCDump(const nsCString& aInputStr)
+{
+  bool doAllTracesGCCCDump = aInputStr.EqualsLiteral("gc log");
+  LOG("FifoWatcher(command:%s) dispatching GC/CC log runnable.", aInputStr.get());
+  RefPtr<GCAndCCLogDumpRunnable> runnable =
+    new GCAndCCLogDumpRunnable(/* identifier = */ EmptyString(),
+                               doAllTracesGCCCDump,
+                               /* dumpChildProcesses = */ true);
+  NS_DispatchToMainThread(runnable);
+}
+
+bool
+SetupFifo()
+{
+#ifdef DEBUG
+  static bool fifoCallbacksRegistered = false;
+#endif
+
+  if (!FifoWatcher::MaybeCreate()) {
+    return false;
+  }
+
+  MOZ_ASSERT(!fifoCallbacksRegistered,
+             "FifoWatcher callbacks should be registered only once");
+
+  FifoWatcher* fw = FifoWatcher::GetSingleton();
+  // Dump our memory reports (but run this on the main thread!).
+  fw->RegisterCallback(NS_LITERAL_CSTRING("memory report"),
+                       doMemoryReport);
+  fw->RegisterCallback(NS_LITERAL_CSTRING("minimize memory report"),
+                       doMemoryReport);
+  // Dump GC and CC logs (from the main thread).
+  fw->RegisterCallback(NS_LITERAL_CSTRING("gc log"),
+                       doGCCCDump);
+  fw->RegisterCallback(NS_LITERAL_CSTRING("abbreviated gc log"),
+                       doGCCCDump);
+
+#ifdef DEBUG
+  fifoCallbacksRegistered = true;
+#endif
+  return true;
+}
+
+void
+OnFifoEnabledChange(const char* /*unused*/, void* /*unused*/)
+{
+  LOG("%s changed", FifoWatcher::kPrefName);
+  if (SetupFifo()) {
+    Preferences::UnregisterCallback(OnFifoEnabledChange,
+                                    FifoWatcher::kPrefName,
+                                    nullptr);
+  }
+}
+
+} // namespace
+#endif // MOZ_SUPPORTS_FIFO }
+
+NS_IMPL_ISUPPORTS(nsMemoryInfoDumper, nsIMemoryInfoDumper)
+
+nsMemoryInfoDumper::nsMemoryInfoDumper()
+{
+}
+
+nsMemoryInfoDumper::~nsMemoryInfoDumper()
+{
+}
+
+/* static */ void
+nsMemoryInfoDumper::Initialize()
+{
+#if defined(MOZ_SUPPORTS_RT_SIGNALS)
+  SignalPipeWatcher* sw = SignalPipeWatcher::GetSingleton();
+
+  // Dump memory reporters (and those of our child processes)
+  sDumpAboutMemorySignum = SIGRTMIN;
+  sw->RegisterCallback(sDumpAboutMemorySignum, doMemoryReport);
+  // Dump our memory reporters after minimizing memory usage
+  sDumpAboutMemoryAfterMMUSignum = SIGRTMIN + 1;
+  sw->RegisterCallback(sDumpAboutMemoryAfterMMUSignum, doMemoryReport);
+  // Dump the GC and CC logs in this and our child processes.
+  sGCAndCCDumpSignum = SIGRTMIN + 2;
+  sw->RegisterCallback(sGCAndCCDumpSignum, doGCCCDump);
+#endif
+
+#if defined(MOZ_SUPPORTS_FIFO)
+  if (!SetupFifo()) {
+    // NB: This gets loaded early enough that it's possible there is a user pref
+    //     set to enable the fifo watcher that has not been loaded yet. Register
+    //     to attempt to initialize if the fifo watcher becomes enabled by
+    //     a user pref.
+    Preferences::RegisterCallback(OnFifoEnabledChange,
+                                  FifoWatcher::kPrefName,
+                                  nullptr);
+  }
+#endif
+}
+
+static void
+EnsureNonEmptyIdentifier(nsAString& aIdentifier)
+{
+  if (!aIdentifier.IsEmpty()) {
+    return;
+  }
+
+  // If the identifier is empty, set it to the number of whole seconds since the
+  // epoch.  This identifier will appear in the files that this process
+  // generates and also the files generated by this process's children, allowing
+  // us to identify which files are from the same memory report request.
+  aIdentifier.AppendInt(static_cast<int64_t>(PR_Now()) / 1000000);
+}
+
+// Use XPCOM refcounting to fire |onFinish| when all reference-holders
+// (remote dump actors or the |DumpGCAndCCLogsToFile| activation itself)
+// have gone away.
+class nsDumpGCAndCCLogsCallbackHolder final
+  : public nsIDumpGCAndCCLogsCallback
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  explicit nsDumpGCAndCCLogsCallbackHolder(nsIDumpGCAndCCLogsCallback* aCallback)
+    : mCallback(aCallback)
+  {
+  }
+
+  NS_IMETHOD OnFinish() override
+  {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  NS_IMETHOD OnDump(nsIFile* aGCLog, nsIFile* aCCLog, bool aIsParent) override
+  {
+    return mCallback->OnDump(aGCLog, aCCLog, aIsParent);
+  }
+
+private:
+  ~nsDumpGCAndCCLogsCallbackHolder()
+  {
+    Unused << mCallback->OnFinish();
+  }
+
+  nsCOMPtr<nsIDumpGCAndCCLogsCallback> mCallback;
+};
+
+NS_IMPL_ISUPPORTS(nsDumpGCAndCCLogsCallbackHolder, nsIDumpGCAndCCLogsCallback)
+
+NS_IMETHODIMP
+nsMemoryInfoDumper::DumpGCAndCCLogsToFile(const nsAString& aIdentifier,
+                                          bool aDumpAllTraces,
+                                          bool aDumpChildProcesses,
+                                          nsIDumpGCAndCCLogsCallback* aCallback)
+{
+  nsString identifier(aIdentifier);
+  EnsureNonEmptyIdentifier(identifier);
+  nsCOMPtr<nsIDumpGCAndCCLogsCallback> callbackHolder =
+    new nsDumpGCAndCCLogsCallbackHolder(aCallback);
+
+  if (aDumpChildProcesses) {
+    nsTArray<ContentParent*> children;
+    ContentParent::GetAll(children);
+    for (uint32_t i = 0; i < children.Length(); i++) {
+      ContentParent* cp = children[i];
+      nsCOMPtr<nsICycleCollectorLogSink> logSink =
+        nsCycleCollector_createLogSink();
+
+      logSink->SetFilenameIdentifier(identifier);
+      logSink->SetProcessIdentifier(cp->Pid());
+
+      Unused << cp->CycleCollectWithLogs(aDumpAllTraces, logSink,
+                                         callbackHolder);
+    }
+  }
+
+  nsCOMPtr<nsICycleCollectorListener> logger =
+    do_CreateInstance("@mozilla.org/cycle-collector-logger;1");
+
+  if (aDumpAllTraces) {
+    nsCOMPtr<nsICycleCollectorListener> allTracesLogger;
+    logger->AllTraces(getter_AddRefs(allTracesLogger));
+    logger = allTracesLogger;
+  }
+
+  nsCOMPtr<nsICycleCollectorLogSink> logSink;
+  logger->GetLogSink(getter_AddRefs(logSink));
+
+  logSink->SetFilenameIdentifier(identifier);
+
+  nsJSContext::CycleCollectNow(logger);
+
+  nsCOMPtr<nsIFile> gcLog, ccLog;
+  logSink->GetGcLog(getter_AddRefs(gcLog));
+  logSink->GetCcLog(getter_AddRefs(ccLog));
+  callbackHolder->OnDump(gcLog, ccLog, /* parent = */ true);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMemoryInfoDumper::DumpGCAndCCLogsToSink(bool aDumpAllTraces,
+                                          nsICycleCollectorLogSink* aSink)
+{
+  nsCOMPtr<nsICycleCollectorListener> logger =
+    do_CreateInstance("@mozilla.org/cycle-collector-logger;1");
+
+  if (aDumpAllTraces) {
+    nsCOMPtr<nsICycleCollectorListener> allTracesLogger;
+    logger->AllTraces(getter_AddRefs(allTracesLogger));
+    logger = allTracesLogger;
+  }
+
+  logger->SetLogSink(aSink);
+
+  nsJSContext::CycleCollectNow(logger);
+
+  return NS_OK;
+}
+
+static void
+MakeFilename(const char* aPrefix, const nsAString& aIdentifier,
+             int aPid, const char* aSuffix, nsACString& aResult)
+{
+  aResult = nsPrintfCString("%s-%s-%d.%s",
+                            aPrefix,
+                            NS_ConvertUTF16toUTF8(aIdentifier).get(),
+                            aPid, aSuffix);
+}
+
+// This class wraps GZFileWriter so it can be used with JSONWriter, overcoming
+// the following two problems:
+// - It provides a JSONWriterFunc::Write() that calls nsGZFileWriter::Write().
+// - It can be stored as a UniquePtr, whereas nsGZFileWriter is refcounted.
+class GZWriterWrapper : public JSONWriteFunc
+{
+public:
+  explicit GZWriterWrapper(nsGZFileWriter* aGZWriter)
+    : mGZWriter(aGZWriter)
+  {}
+
+  void Write(const char* aStr)
+  {
+    // Ignore any failure because JSONWriteFunc doesn't have a mechanism for
+    // handling errors.
+    Unused << mGZWriter->Write(aStr);
+  }
+
+  nsresult Finish() { return mGZWriter->Finish(); }
+
+private:
+  RefPtr<nsGZFileWriter> mGZWriter;
+};
+
+// We need two callbacks: one that handles reports, and one that is called at
+// the end of reporting. Both the callbacks need access to the same JSONWriter,
+// so we implement both of them in this one class.
+class HandleReportAndFinishReportingCallbacks final
+  : public nsIHandleReportCallback, public nsIFinishReportingCallback
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  HandleReportAndFinishReportingCallbacks(UniquePtr<JSONWriter> aWriter,
+                                          nsIFinishDumpingCallback* aFinishDumping,
+                                          nsISupports* aFinishDumpingData)
+    : mWriter(Move(aWriter))
+    , mFinishDumping(aFinishDumping)
+    , mFinishDumpingData(aFinishDumpingData)
+  {
+  }
+
+  // This is the callback for nsIHandleReportCallback.
+  NS_IMETHOD Callback(const nsACString& aProcess, const nsACString& aPath,
+                      int32_t aKind, int32_t aUnits, int64_t aAmount,
+                      const nsACString& aDescription,
+                      nsISupports* aData) override
+  {
+    nsAutoCString process;
+    if (aProcess.IsEmpty()) {
+      // If the process is empty, the report originated with the process doing
+      // the dumping.  In that case, generate the process identifier, which is
+      // of the form "$PROCESS_NAME (pid $PID)", or just "(pid $PID)" if we
+      // don't have a process name.  If we're the main process, we let
+      // $PROCESS_NAME be "Main Process".
+      if (XRE_IsParentProcess()) {
+        // We're the main process.
+        process.AssignLiteral("Main Process");
+      } else if (ContentChild* cc = ContentChild::GetSingleton()) {
+        // Try to get the process name from ContentChild.
+        cc->GetProcessName(process);
+      }
+      ContentChild::AppendProcessId(process);
+
+    } else {
+      // Otherwise, the report originated with another process and already has a
+      // process name.  Just use that.
+      process = aProcess;
+    }
+
+    mWriter->StartObjectElement();
+    {
+      mWriter->StringProperty("process", process.get());
+      mWriter->StringProperty("path", PromiseFlatCString(aPath).get());
+      mWriter->IntProperty("kind", aKind);
+      mWriter->IntProperty("units", aUnits);
+      mWriter->IntProperty("amount", aAmount);
+      mWriter->StringProperty("description",
+                              PromiseFlatCString(aDescription).get());
+    }
+    mWriter->EndObject();
+
+    return NS_OK;
+  }
+
+  // This is the callback for nsIFinishReportingCallback.
+  NS_IMETHOD Callback(nsISupports* aData) override
+  {
+    mWriter->EndArray();  // end of "reports" array
+    mWriter->End();
+
+    // The call to Finish() deallocates the memory allocated by the first Write
+    // call. Because that memory was live while the memory reporters ran and
+    // was measured by them -- by "heap-allocated" if nothing else -- we want
+    // DMD to see it as well. So we deliberately don't call Finish() until
+    // after DMD finishes.
+    nsresult rv = static_cast<GZWriterWrapper*>(mWriter->WriteFunc())->Finish();
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    if (!mFinishDumping) {
+      return NS_OK;
+    }
+
+    return mFinishDumping->Callback(mFinishDumpingData);
+  }
+
+private:
+  ~HandleReportAndFinishReportingCallbacks() {}
+
+  UniquePtr<JSONWriter> mWriter;
+  nsCOMPtr<nsIFinishDumpingCallback> mFinishDumping;
+  nsCOMPtr<nsISupports> mFinishDumpingData;
+};
+
+NS_IMPL_ISUPPORTS(HandleReportAndFinishReportingCallbacks,
+                  nsIHandleReportCallback, nsIFinishReportingCallback)
+
+class TempDirFinishCallback final : public nsIFinishDumpingCallback
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  TempDirFinishCallback(nsIFile* aReportsTmpFile,
+                        const nsCString& aReportsFinalFilename)
+    : mReportsTmpFile(aReportsTmpFile)
+    , mReportsFilename(aReportsFinalFilename)
+  {
+  }
+
+  NS_IMETHOD Callback(nsISupports* aData) override
+  {
+    // Rename the memory reports file, now that we're done writing all the
+    // files. Its final name is "memory-report<-identifier>-<pid>.json.gz".
+
+    nsCOMPtr<nsIFile> reportsFinalFile;
+    nsresult rv = NS_GetSpecialDirectory(NS_OS_TEMP_DIR,
+                                         getter_AddRefs(reportsFinalFile));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+  #ifdef ANDROID
+    rv = reportsFinalFile->AppendNative(NS_LITERAL_CSTRING("memory-reports"));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  #endif
+
+    rv = reportsFinalFile->AppendNative(mReportsFilename);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    rv = reportsFinalFile->CreateUnique(nsIFile::NORMAL_FILE_TYPE, 0600);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    nsAutoString reportsFinalFilename;
+    rv = reportsFinalFile->GetLeafName(reportsFinalFilename);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    rv = mReportsTmpFile->MoveTo(/* directory */ nullptr,
+                                 reportsFinalFilename);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    // Write a message to the console.
+
+    nsCOMPtr<nsIConsoleService> cs =
+      do_GetService(NS_CONSOLESERVICE_CONTRACTID, &rv);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    nsString path;
+    mReportsTmpFile->GetPath(path);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    nsString msg = NS_LITERAL_STRING("nsIMemoryInfoDumper dumped reports to ");
+    msg.Append(path);
+    return cs->LogStringMessage(msg.get());
+  }
+
+private:
+  ~TempDirFinishCallback() {}
+
+  nsCOMPtr<nsIFile> mReportsTmpFile;
+  nsCString mReportsFilename;
+};
+
+NS_IMPL_ISUPPORTS(TempDirFinishCallback, nsIFinishDumpingCallback)
+
+static nsresult
+DumpMemoryInfoToFile(
+  nsIFile* aReportsFile,
+  nsIFinishDumpingCallback* aFinishDumping,
+  nsISupports* aFinishDumpingData,
+  bool aAnonymize,
+  bool aMinimizeMemoryUsage,
+  nsAString& aDMDIdentifier)
+{
+  RefPtr<nsGZFileWriter> gzWriter = new nsGZFileWriter();
+  nsresult rv = gzWriter->Init(aReportsFile);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+  auto jsonWriter =
+    MakeUnique<JSONWriter>(MakeUnique<GZWriterWrapper>(gzWriter));
+
+  nsCOMPtr<nsIMemoryReporterManager> mgr =
+    do_GetService("@mozilla.org/memory-reporter-manager;1");
+
+  // This is the first write to the file, and it causes |aWriter| to allocate
+  // over 200 KiB of memory.
+  jsonWriter->Start();
+  {
+    // Increment this number if the format changes.
+    jsonWriter->IntProperty("version", 1);
+    jsonWriter->BoolProperty("hasMozMallocUsableSize",
+                             mgr->GetHasMozMallocUsableSize());
+    jsonWriter->StartArrayProperty("reports");
+  }
+
+  RefPtr<HandleReportAndFinishReportingCallbacks>
+    handleReportAndFinishReporting =
+      new HandleReportAndFinishReportingCallbacks(Move(jsonWriter),
+                                                  aFinishDumping,
+                                                  aFinishDumpingData);
+  rv = mgr->GetReportsExtended(handleReportAndFinishReporting, nullptr,
+                               handleReportAndFinishReporting, nullptr,
+                               aAnonymize,
+                               aMinimizeMemoryUsage,
+                               aDMDIdentifier);
+  return rv;
+}
+
+NS_IMETHODIMP
+nsMemoryInfoDumper::DumpMemoryReportsToNamedFile(
+  const nsAString& aFilename,
+  nsIFinishDumpingCallback* aFinishDumping,
+  nsISupports* aFinishDumpingData,
+  bool aAnonymize)
+{
+  MOZ_ASSERT(!aFilename.IsEmpty());
+
+  // Create the file.
+
+  nsCOMPtr<nsIFile> reportsFile;
+  nsresult rv = NS_NewLocalFile(aFilename, false, getter_AddRefs(reportsFile));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  reportsFile->InitWithPath(aFilename);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  bool exists;
+  rv = reportsFile->Exists(&exists);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  if (!exists) {
+    rv = reportsFile->Create(nsIFile::NORMAL_FILE_TYPE, 0644);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+  nsString dmdIdent = EmptyString();
+  return DumpMemoryInfoToFile(reportsFile, aFinishDumping, aFinishDumpingData,
+                              aAnonymize, /* minimizeMemoryUsage = */ false,
+                              dmdIdent);
+}
+
+NS_IMETHODIMP
+nsMemoryInfoDumper::DumpMemoryInfoToTempDir(const nsAString& aIdentifier,
+                                            bool aAnonymize,
+                                            bool aMinimizeMemoryUsage)
+{
+  nsString identifier(aIdentifier);
+  EnsureNonEmptyIdentifier(identifier);
+
+  // Open a new file named something like
+  //
+  //   incomplete-memory-report-<identifier>-<pid>.json.gz
+  //
+  // in NS_OS_TEMP_DIR for writing.  When we're finished writing the report,
+  // we'll rename this file and get rid of the "incomplete-" prefix.
+  //
+  // We do this because we don't want scripts which poll the filesystem
+  // looking for memory report dumps to grab a file before we're finished
+  // writing to it.
+
+  // The "unified" indicates that we merge the memory reports from all
+  // processes and write out one file, rather than a separate file for
+  // each process as was the case before bug 946407.  This is so that
+  // the get_about_memory.py script in the B2G repository can
+  // determine when it's done waiting for files to appear.
+  nsCString reportsFinalFilename;
+  MakeFilename("unified-memory-report", identifier, getpid(), "json.gz",
+               reportsFinalFilename);
+
+  nsCOMPtr<nsIFile> reportsTmpFile;
+  nsresult rv;
+  // In Android case, this function will open a file named aFilename under
+  // specific folder (/data/local/tmp/memory-reports). Otherwise, it will
+  // open a file named aFilename under "NS_OS_TEMP_DIR".
+  rv = nsDumpUtils::OpenTempFile(NS_LITERAL_CSTRING("incomplete-") +
+                                 reportsFinalFilename,
+                                 getter_AddRefs(reportsTmpFile),
+                                 NS_LITERAL_CSTRING("memory-reports"));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  RefPtr<TempDirFinishCallback> finishDumping =
+    new TempDirFinishCallback(reportsTmpFile, reportsFinalFilename);
+
+  return DumpMemoryInfoToFile(reportsTmpFile, finishDumping, nullptr,
+                              aAnonymize, aMinimizeMemoryUsage, identifier);
+}
+
+#ifdef MOZ_DMD
+dmd::DMDFuncs::Singleton dmd::DMDFuncs::sSingleton;
+
+nsresult
+nsMemoryInfoDumper::OpenDMDFile(const nsAString& aIdentifier, int aPid,
+                                FILE** aOutFile)
+{
+  if (!dmd::IsRunning()) {
+    *aOutFile = nullptr;
+    return NS_OK;
+  }
+
+  // Create a filename like dmd-<identifier>-<pid>.json.gz, which will be used
+  // if DMD is enabled.
+  nsCString dmdFilename;
+  MakeFilename("dmd", aIdentifier, aPid, "json.gz", dmdFilename);
+
+  // Open a new DMD file named |dmdFilename| in NS_OS_TEMP_DIR for writing,
+  // and dump DMD output to it.  This must occur after the memory reporters
+  // have been run (above), but before the memory-reports file has been
+  // renamed (so scripts can detect the DMD file, if present).
+
+  nsresult rv;
+  nsCOMPtr<nsIFile> dmdFile;
+  rv = nsDumpUtils::OpenTempFile(dmdFilename,
+                                 getter_AddRefs(dmdFile),
+                                 NS_LITERAL_CSTRING("memory-reports"));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+  rv = dmdFile->OpenANSIFileDesc("wb", aOutFile);
+  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "OpenANSIFileDesc failed");
+
+  // Print the path, because on some platforms (e.g. Mac) it's not obvious.
+  nsCString path;
+  rv = dmdFile->GetNativePath(path);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+  dmd::StatusMsg("opened %s for writing\n", path.get());
+
+  return rv;
+}
+
+nsresult
+nsMemoryInfoDumper::DumpDMDToFile(FILE* aFile)
+{
+  RefPtr<nsGZFileWriter> gzWriter = new nsGZFileWriter();
+  nsresult rv = gzWriter->InitANSIFileDesc(aFile);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  // Dump DMD's memory reports analysis to the file.
+  dmd::Analyze(MakeUnique<GZWriterWrapper>(gzWriter));
+
+  rv = gzWriter->Finish();
+  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "Finish failed");
+  return rv;
+}
+#endif  // MOZ_DMD
+
diff --git a/xpcom/base/nsMemoryInfoDumper.h b/xpcom/base/nsMemoryInfoDumper.h
new file mode 100644
index 000000000..6bba176f2
--- /dev/null
+++ b/xpcom/base/nsMemoryInfoDumper.h
@@ -0,0 +1,46 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_nsMemoryInfoDumper_h
+#define mozilla_nsMemoryInfoDumper_h
+
+#include "nsIMemoryInfoDumper.h"
+#include <stdio.h>
+
+/**
+ * This class facilitates dumping information about our memory usage to disk.
+ *
+ * Its cpp file also has Linux-only code which watches various OS signals and
+ * dumps memory info upon receiving a signal.  You can activate these listeners
+ * by calling Initialize().
+ */
+class nsMemoryInfoDumper : public nsIMemoryInfoDumper
+{
+  virtual ~nsMemoryInfoDumper();
+
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIMEMORYINFODUMPER
+
+  nsMemoryInfoDumper();
+
+  static void Initialize();
+
+#ifdef MOZ_DMD
+  // Open an appropriately named file for a DMD report.  If DMD is
+  // disabled, return a null FILE* instead.
+  static nsresult OpenDMDFile(const nsAString& aIdentifier, int aPid,
+                              FILE** aOutFile);
+  // Write a DMD report to the given file and close it.
+  static nsresult DumpDMDToFile(FILE* aFile);
+#endif
+};
+
+#define NS_MEMORY_INFO_DUMPER_CID \
+{ 0x00bd71fb, 0x7f09, 0x4ec3, \
+{ 0x96, 0xaf, 0xa0, 0xb5, 0x22, 0xb7, 0x79, 0x69 } }
+
+#endif
diff --git a/xpcom/base/nsMemoryReporterManager.cpp b/xpcom/base/nsMemoryReporterManager.cpp
new file mode 100644
index 000000000..aa3d74dfd
--- /dev/null
+++ b/xpcom/base/nsMemoryReporterManager.cpp
@@ -0,0 +1,2717 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsAtomTable.h"
+#include "nsAutoPtr.h"
+#include "nsCOMPtr.h"
+#include "nsCOMArray.h"
+#include "nsPrintfCString.h"
+#include "nsServiceManagerUtils.h"
+#include "nsMemoryReporterManager.h"
+#include "nsITimer.h"
+#include "nsThreadUtils.h"
+#include "nsPIDOMWindow.h"
+#include "nsIObserverService.h"
+#include "nsIGlobalObject.h"
+#include "nsIXPConnect.h"
+#if defined(XP_UNIX) || defined(MOZ_DMD)
+#include "nsMemoryInfoDumper.h"
+#endif
+#include "mozilla/Attributes.h"
+#include "mozilla/PodOperations.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/Services.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/UniquePtrExtensions.h"
+#include "mozilla/dom/PMemoryReportRequestParent.h" // for dom::MemoryReport
+#include "mozilla/dom/ContentParent.h"
+#include "mozilla/ipc/FileDescriptorUtils.h"
+
+#ifdef XP_WIN
+#include <process.h>
+#ifndef getpid
+#define getpid _getpid
+#endif
+#else
+#include <unistd.h>
+#endif
+
+using namespace mozilla;
+
+#if defined(MOZ_MEMORY)
+#  define HAVE_JEMALLOC_STATS 1
+#  include "mozmemory.h"
+#endif  // MOZ_MEMORY
+
+#if defined(XP_LINUX)
+
+#include <malloc.h>
+#include <string.h>
+#include <stdlib.h>
+
+static MOZ_MUST_USE nsresult
+GetProcSelfStatmField(int aField, int64_t* aN)
+{
+  // There are more than two fields, but we're only interested in the first
+  // two.
+  static const int MAX_FIELD = 2;
+  size_t fields[MAX_FIELD];
+  MOZ_ASSERT(aField < MAX_FIELD, "bad field number");
+  FILE* f = fopen("/proc/self/statm", "r");
+  if (f) {
+    int nread = fscanf(f, "%zu %zu", &fields[0], &fields[1]);
+    fclose(f);
+    if (nread == MAX_FIELD) {
+      *aN = fields[aField] * getpagesize();
+      return NS_OK;
+    }
+  }
+  return NS_ERROR_FAILURE;
+}
+
+static MOZ_MUST_USE nsresult
+GetProcSelfSmapsPrivate(int64_t* aN)
+{
+  // You might be tempted to calculate USS by subtracting the "shared" value
+  // from the "resident" value in /proc/<pid>/statm. But at least on Linux,
+  // statm's "shared" value actually counts pages backed by files, which has
+  // little to do with whether the pages are actually shared. /proc/self/smaps
+  // on the other hand appears to give us the correct information.
+
+  FILE* f = fopen("/proc/self/smaps", "r");
+  if (NS_WARN_IF(!f)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  // We carry over the end of the buffer to the beginning to make sure we only
+  // interpret complete lines.
+  static const uint32_t carryOver = 32;
+  static const uint32_t readSize = 4096;
+
+  int64_t amount = 0;
+  char buffer[carryOver + readSize + 1];
+
+  // Fill the beginning of the buffer with spaces, as a sentinel for the first
+  // iteration.
+  memset(buffer, ' ', carryOver);
+
+  for (;;) {
+    size_t bytes = fread(buffer + carryOver, sizeof(*buffer), readSize, f);
+    char* end = buffer + bytes;
+    char* ptr = buffer;
+    end[carryOver] = '\0';
+    // We are looking for lines like "Private_{Clean,Dirty}: 4 kB".
+    while ((ptr = strstr(ptr, "Private"))) {
+      if (ptr >= end) {
+        break;
+      }
+      ptr += sizeof("Private_Xxxxx:");
+      amount += strtol(ptr, nullptr, 10);
+    }
+    if (bytes < readSize) {
+      // We do not expect any match within the end of the buffer.
+      MOZ_ASSERT(!strstr(end, "Private"));
+      break;
+    }
+    // Carry the end of the buffer over to the beginning.
+    memcpy(buffer, end, carryOver);
+  }
+
+  fclose(f);
+  // Convert from kB to bytes.
+  *aN = amount * 1024;
+  return NS_OK;
+}
+
+#define HAVE_VSIZE_AND_RESIDENT_REPORTERS 1
+static MOZ_MUST_USE nsresult
+VsizeDistinguishedAmount(int64_t* aN)
+{
+  return GetProcSelfStatmField(0, aN);
+}
+
+static MOZ_MUST_USE nsresult
+ResidentDistinguishedAmount(int64_t* aN)
+{
+  return GetProcSelfStatmField(1, aN);
+}
+
+static MOZ_MUST_USE nsresult
+ResidentFastDistinguishedAmount(int64_t* aN)
+{
+  return ResidentDistinguishedAmount(aN);
+}
+
+#define HAVE_RESIDENT_UNIQUE_REPORTER 1
+static MOZ_MUST_USE nsresult
+ResidentUniqueDistinguishedAmount(int64_t* aN)
+{
+  return GetProcSelfSmapsPrivate(aN);
+}
+
+#ifdef HAVE_MALLINFO
+#define HAVE_SYSTEM_HEAP_REPORTER 1
+static MOZ_MUST_USE nsresult
+SystemHeapSize(int64_t* aSizeOut)
+{
+    struct mallinfo info = mallinfo();
+
+    // The documentation in the glibc man page makes it sound like |uordblks|
+    // would suffice, but that only gets the small allocations that are put in
+    // the brk heap. We need |hblkhd| as well to get the larger allocations
+    // that are mmapped.
+    //
+    // The fields in |struct mallinfo| are all |int|, <sigh>, so it is
+    // unreliable if memory usage gets high. However, the system heap size on
+    // Linux should usually be zero (so long as jemalloc is enabled) so that
+    // shouldn't be a problem. Nonetheless, cast the |int|s to |size_t| before
+    // adding them to provide a small amount of extra overflow protection.
+    *aSizeOut = size_t(info.hblkhd) + size_t(info.uordblks);
+    return NS_OK;
+}
+#endif
+
+#elif defined(__DragonFly__) || defined(__FreeBSD__) \
+    || defined(__NetBSD__) || defined(__OpenBSD__) \
+    || defined(__FreeBSD_kernel__)
+
+#include <sys/param.h>
+#include <sys/sysctl.h>
+#if defined(__DragonFly__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+#include <sys/user.h>
+#endif
+
+#include <unistd.h>
+
+#if defined(__NetBSD__)
+#undef KERN_PROC
+#define KERN_PROC KERN_PROC2
+#define KINFO_PROC struct kinfo_proc2
+#else
+#define KINFO_PROC struct kinfo_proc
+#endif
+
+#if defined(__DragonFly__)
+#define KP_SIZE(kp) (kp.kp_vm_map_size)
+#define KP_RSS(kp) (kp.kp_vm_rssize * getpagesize())
+#elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+#define KP_SIZE(kp) (kp.ki_size)
+#define KP_RSS(kp) (kp.ki_rssize * getpagesize())
+#elif defined(__NetBSD__)
+#define KP_SIZE(kp) (kp.p_vm_msize * getpagesize())
+#define KP_RSS(kp) (kp.p_vm_rssize * getpagesize())
+#elif defined(__OpenBSD__)
+#define KP_SIZE(kp) ((kp.p_vm_dsize + kp.p_vm_ssize                     \
+                      + kp.p_vm_tsize) * getpagesize())
+#define KP_RSS(kp) (kp.p_vm_rssize * getpagesize())
+#endif
+
+static MOZ_MUST_USE nsresult
+GetKinfoProcSelf(KINFO_PROC* aProc)
+{
+  int mib[] = {
+    CTL_KERN,
+    KERN_PROC,
+    KERN_PROC_PID,
+    getpid(),
+#if defined(__NetBSD__) || defined(__OpenBSD__)
+    sizeof(KINFO_PROC),
+    1,
+#endif
+  };
+  u_int miblen = sizeof(mib) / sizeof(mib[0]);
+  size_t size = sizeof(KINFO_PROC);
+  if (sysctl(mib, miblen, aProc, &size, nullptr, 0)) {
+    return NS_ERROR_FAILURE;
+  }
+  return NS_OK;
+}
+
+#define HAVE_VSIZE_AND_RESIDENT_REPORTERS 1
+static MOZ_MUST_USE nsresult
+VsizeDistinguishedAmount(int64_t* aN)
+{
+  KINFO_PROC proc;
+  nsresult rv = GetKinfoProcSelf(&proc);
+  if (NS_SUCCEEDED(rv)) {
+    *aN = KP_SIZE(proc);
+  }
+  return rv;
+}
+
+static MOZ_MUST_USE nsresult
+ResidentDistinguishedAmount(int64_t* aN)
+{
+  KINFO_PROC proc;
+  nsresult rv = GetKinfoProcSelf(&proc);
+  if (NS_SUCCEEDED(rv)) {
+    *aN = KP_RSS(proc);
+  }
+  return rv;
+}
+
+static MOZ_MUST_USE nsresult
+ResidentFastDistinguishedAmount(int64_t* aN)
+{
+  return ResidentDistinguishedAmount(aN);
+}
+
+#ifdef __FreeBSD__
+#include <libutil.h>
+#include <algorithm>
+
+static MOZ_MUST_USE nsresult
+GetKinfoVmentrySelf(int64_t* aPrss, uint64_t* aMaxreg)
+{
+  int cnt;
+  struct kinfo_vmentry* vmmap;
+  struct kinfo_vmentry* kve;
+  if (!(vmmap = kinfo_getvmmap(getpid(), &cnt))) {
+    return NS_ERROR_FAILURE;
+  }
+  if (aPrss) {
+    *aPrss = 0;
+  }
+  if (aMaxreg) {
+    *aMaxreg = 0;
+  }
+
+  for (int i = 0; i < cnt; i++) {
+    kve = &vmmap[i];
+    if (aPrss) {
+      *aPrss += kve->kve_private_resident;
+    }
+    if (aMaxreg) {
+      *aMaxreg = std::max(*aMaxreg, kve->kve_end - kve->kve_start);
+    }
+  }
+
+  free(vmmap);
+  return NS_OK;
+}
+
+#define HAVE_PRIVATE_REPORTER 1
+static MOZ_MUST_USE nsresult
+PrivateDistinguishedAmount(int64_t* aN)
+{
+  int64_t priv;
+  nsresult rv = GetKinfoVmentrySelf(&priv, nullptr);
+  NS_ENSURE_SUCCESS(rv, rv);
+  *aN = priv * getpagesize();
+  return NS_OK;
+}
+
+#define HAVE_VSIZE_MAX_CONTIGUOUS_REPORTER 1
+static MOZ_MUST_USE nsresult
+VsizeMaxContiguousDistinguishedAmount(int64_t* aN)
+{
+  uint64_t biggestRegion;
+  nsresult rv = GetKinfoVmentrySelf(nullptr, &biggestRegion);
+  if (NS_SUCCEEDED(rv)) {
+    *aN = biggestRegion;
+  }
+  return NS_OK;
+}
+#endif // FreeBSD
+
+#elif defined(SOLARIS)
+
+#include <procfs.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+static void
+XMappingIter(int64_t& aVsize, int64_t& aResident)
+{
+  aVsize = -1;
+  aResident = -1;
+  int mapfd = open("/proc/self/xmap", O_RDONLY);
+  struct stat st;
+  prxmap_t* prmapp = nullptr;
+  if (mapfd >= 0) {
+    if (!fstat(mapfd, &st)) {
+      int nmap = st.st_size / sizeof(prxmap_t);
+      while (1) {
+        // stat(2) on /proc/<pid>/xmap returns an incorrect value,
+        // prior to the release of Solaris 11.
+        // Here is a workaround for it.
+        nmap *= 2;
+        prmapp = (prxmap_t*)malloc((nmap + 1) * sizeof(prxmap_t));
+        if (!prmapp) {
+          // out of memory
+          break;
+        }
+        int n = pread(mapfd, prmapp, (nmap + 1) * sizeof(prxmap_t), 0);
+        if (n < 0) {
+          break;
+        }
+        if (nmap >= n / sizeof(prxmap_t)) {
+          aVsize = 0;
+          aResident = 0;
+          for (int i = 0; i < n / sizeof(prxmap_t); i++) {
+            aVsize += prmapp[i].pr_size;
+            aResident += prmapp[i].pr_rss * prmapp[i].pr_pagesize;
+          }
+          break;
+        }
+        free(prmapp);
+      }
+      free(prmapp);
+    }
+    close(mapfd);
+  }
+}
+
+#define HAVE_VSIZE_AND_RESIDENT_REPORTERS 1
+static MOZ_MUST_USE nsresult
+VsizeDistinguishedAmount(int64_t* aN)
+{
+  int64_t vsize, resident;
+  XMappingIter(vsize, resident);
+  if (vsize == -1) {
+    return NS_ERROR_FAILURE;
+  }
+  *aN = vsize;
+  return NS_OK;
+}
+
+static MOZ_MUST_USE nsresult
+ResidentDistinguishedAmount(int64_t* aN)
+{
+  int64_t vsize, resident;
+  XMappingIter(vsize, resident);
+  if (resident == -1) {
+    return NS_ERROR_FAILURE;
+  }
+  *aN = resident;
+  return NS_OK;
+}
+
+static MOZ_MUST_USE nsresult
+ResidentFastDistinguishedAmount(int64_t* aN)
+{
+  return ResidentDistinguishedAmount(aN);
+}
+
+#elif defined(XP_MACOSX)
+
+#include <mach/mach_init.h>
+#include <mach/mach_vm.h>
+#include <mach/shared_region.h>
+#include <mach/task.h>
+#include <sys/sysctl.h>
+
+static MOZ_MUST_USE bool
+GetTaskBasicInfo(struct task_basic_info* aTi)
+{
+  mach_msg_type_number_t count = TASK_BASIC_INFO_COUNT;
+  kern_return_t kr = task_info(mach_task_self(), TASK_BASIC_INFO,
+                               (task_info_t)aTi, &count);
+  return kr == KERN_SUCCESS;
+}
+
+// The VSIZE figure on Mac includes huge amounts of shared memory and is always
+// absurdly high, eg. 2GB+ even at start-up.  But both 'top' and 'ps' report
+// it, so we might as well too.
+#define HAVE_VSIZE_AND_RESIDENT_REPORTERS 1
+static MOZ_MUST_USE nsresult
+VsizeDistinguishedAmount(int64_t* aN)
+{
+  task_basic_info ti;
+  if (!GetTaskBasicInfo(&ti)) {
+    return NS_ERROR_FAILURE;
+  }
+  *aN = ti.virtual_size;
+  return NS_OK;
+}
+
+// If we're using jemalloc on Mac, we need to instruct jemalloc to purge the
+// pages it has madvise(MADV_FREE)'d before we read our RSS in order to get
+// an accurate result.  The OS will take away MADV_FREE'd pages when there's
+// memory pressure, so ideally, they shouldn't count against our RSS.
+//
+// Purging these pages can take a long time for some users (see bug 789975),
+// so we provide the option to get the RSS without purging first.
+static MOZ_MUST_USE nsresult
+ResidentDistinguishedAmountHelper(int64_t* aN, bool aDoPurge)
+{
+#ifdef HAVE_JEMALLOC_STATS
+#ifndef MOZ_JEMALLOC4
+  if (aDoPurge) {
+    Telemetry::AutoTimer<Telemetry::MEMORY_FREE_PURGED_PAGES_MS> timer;
+    jemalloc_purge_freed_pages();
+  }
+#endif
+#endif
+
+  task_basic_info ti;
+  if (!GetTaskBasicInfo(&ti)) {
+    return NS_ERROR_FAILURE;
+  }
+  *aN = ti.resident_size;
+  return NS_OK;
+}
+
+static MOZ_MUST_USE nsresult
+ResidentFastDistinguishedAmount(int64_t* aN)
+{
+  return ResidentDistinguishedAmountHelper(aN, /* doPurge = */ false);
+}
+
+static MOZ_MUST_USE nsresult
+ResidentDistinguishedAmount(int64_t* aN)
+{
+  return ResidentDistinguishedAmountHelper(aN, /* doPurge = */ true);
+}
+
+#define HAVE_RESIDENT_UNIQUE_REPORTER 1
+
+static bool
+InSharedRegion(mach_vm_address_t aAddr, cpu_type_t aType)
+{
+  mach_vm_address_t base;
+  mach_vm_address_t size;
+
+  switch (aType) {
+    case CPU_TYPE_ARM:
+      base = SHARED_REGION_BASE_ARM;
+      size = SHARED_REGION_SIZE_ARM;
+      break;
+    case CPU_TYPE_I386:
+      base = SHARED_REGION_BASE_I386;
+      size = SHARED_REGION_SIZE_I386;
+      break;
+    case CPU_TYPE_X86_64:
+      base = SHARED_REGION_BASE_X86_64;
+      size = SHARED_REGION_SIZE_X86_64;
+      break;
+    default:
+      return false;
+  }
+
+  return base <= aAddr && aAddr < (base + size);
+}
+
+static MOZ_MUST_USE nsresult
+ResidentUniqueDistinguishedAmount(int64_t* aN)
+{
+  if (!aN) {
+    return NS_ERROR_FAILURE;
+  }
+
+  cpu_type_t cpu_type;
+  size_t len = sizeof(cpu_type);
+  if (sysctlbyname("sysctl.proc_cputype", &cpu_type, &len, NULL, 0) != 0) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Roughly based on libtop_update_vm_regions in
+  // http://www.opensource.apple.com/source/top/top-100.1.2/libtop.c
+  size_t privatePages = 0;
+  mach_vm_size_t size = 0;
+  for (mach_vm_address_t addr = MACH_VM_MIN_ADDRESS; ; addr += size) {
+    vm_region_top_info_data_t info;
+    mach_msg_type_number_t infoCount = VM_REGION_TOP_INFO_COUNT;
+    mach_port_t objectName;
+
+    kern_return_t kr =
+        mach_vm_region(mach_task_self(), &addr, &size, VM_REGION_TOP_INFO,
+                       reinterpret_cast<vm_region_info_t>(&info),
+                       &infoCount, &objectName);
+    if (kr == KERN_INVALID_ADDRESS) {
+      // Done iterating VM regions.
+      break;
+    } else if (kr != KERN_SUCCESS) {
+      return NS_ERROR_FAILURE;
+    }
+
+    if (InSharedRegion(addr, cpu_type) && info.share_mode != SM_PRIVATE) {
+        continue;
+    }
+
+    switch (info.share_mode) {
+      case SM_LARGE_PAGE:
+        // NB: Large pages are not shareable and always resident.
+      case SM_PRIVATE:
+        privatePages += info.private_pages_resident;
+        privatePages += info.shared_pages_resident;
+        break;
+      case SM_COW:
+        privatePages += info.private_pages_resident;
+        if (info.ref_count == 1) {
+          // Treat copy-on-write pages as private if they only have one reference.
+          privatePages += info.shared_pages_resident;
+        }
+        break;
+      case SM_SHARED:
+      default:
+        break;
+    }
+  }
+
+  vm_size_t pageSize;
+  if (host_page_size(mach_host_self(), &pageSize) != KERN_SUCCESS) {
+    pageSize = PAGE_SIZE;
+  }
+
+  *aN = privatePages * pageSize;
+  return NS_OK;
+}
+
+#elif defined(XP_WIN)
+
+#include <windows.h>
+#include <psapi.h>
+#include <algorithm>
+
+#define HAVE_VSIZE_AND_RESIDENT_REPORTERS 1
+static MOZ_MUST_USE nsresult
+VsizeDistinguishedAmount(int64_t* aN)
+{
+  MEMORYSTATUSEX s;
+  s.dwLength = sizeof(s);
+
+  if (!GlobalMemoryStatusEx(&s)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  *aN = s.ullTotalVirtual - s.ullAvailVirtual;
+  return NS_OK;
+}
+
+static MOZ_MUST_USE nsresult
+ResidentDistinguishedAmount(int64_t* aN)
+{
+  PROCESS_MEMORY_COUNTERS pmc;
+  pmc.cb = sizeof(PROCESS_MEMORY_COUNTERS);
+
+  if (!GetProcessMemoryInfo(GetCurrentProcess(), &pmc, sizeof(pmc))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  *aN = pmc.WorkingSetSize;
+  return NS_OK;
+}
+
+static MOZ_MUST_USE nsresult
+ResidentFastDistinguishedAmount(int64_t* aN)
+{
+  return ResidentDistinguishedAmount(aN);
+}
+
+#define HAVE_RESIDENT_UNIQUE_REPORTER 1
+
+static MOZ_MUST_USE nsresult
+ResidentUniqueDistinguishedAmount(int64_t* aN)
+{
+  // Determine how many entries we need.
+  PSAPI_WORKING_SET_INFORMATION tmp;
+  DWORD tmpSize = sizeof(tmp);
+  memset(&tmp, 0, tmpSize);
+
+  HANDLE proc = GetCurrentProcess();
+  QueryWorkingSet(proc, &tmp, tmpSize);
+
+  // Fudge the size in case new entries are added between calls.
+  size_t entries = tmp.NumberOfEntries * 2;
+
+  if (!entries) {
+    return NS_ERROR_FAILURE;
+  }
+
+  DWORD infoArraySize = tmpSize + (entries * sizeof(PSAPI_WORKING_SET_BLOCK));
+  UniqueFreePtr<PSAPI_WORKING_SET_INFORMATION> infoArray(
+      static_cast<PSAPI_WORKING_SET_INFORMATION*>(malloc(infoArraySize)));
+
+  if (!infoArray) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (!QueryWorkingSet(proc, infoArray.get(), infoArraySize)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  entries = static_cast<size_t>(infoArray->NumberOfEntries);
+  size_t privatePages = 0;
+  for (size_t i = 0; i < entries; i++) {
+    // Count shared pages that only one process is using as private.
+    if (!infoArray->WorkingSetInfo[i].Shared ||
+        infoArray->WorkingSetInfo[i].ShareCount <= 1) {
+      privatePages++;
+    }
+  }
+
+  SYSTEM_INFO si;
+  GetSystemInfo(&si);
+
+  *aN = privatePages * si.dwPageSize;
+  return NS_OK;
+}
+
+#define HAVE_VSIZE_MAX_CONTIGUOUS_REPORTER 1
+static MOZ_MUST_USE nsresult
+VsizeMaxContiguousDistinguishedAmount(int64_t* aN)
+{
+  SIZE_T biggestRegion = 0;
+  MEMORY_BASIC_INFORMATION vmemInfo = { 0 };
+  for (size_t currentAddress = 0; ; ) {
+    if (!VirtualQuery((LPCVOID)currentAddress, &vmemInfo, sizeof(vmemInfo))) {
+      // Something went wrong, just return whatever we've got already.
+      break;
+    }
+
+    if (vmemInfo.State == MEM_FREE) {
+      biggestRegion = std::max(biggestRegion, vmemInfo.RegionSize);
+    }
+
+    SIZE_T lastAddress = currentAddress;
+    currentAddress += vmemInfo.RegionSize;
+
+    // If we overflow, we've examined all of the address space.
+    if (currentAddress < lastAddress) {
+      break;
+    }
+  }
+
+  *aN = biggestRegion;
+  return NS_OK;
+}
+
+#define HAVE_PRIVATE_REPORTER 1
+static MOZ_MUST_USE nsresult
+PrivateDistinguishedAmount(int64_t* aN)
+{
+  PROCESS_MEMORY_COUNTERS_EX pmcex;
+  pmcex.cb = sizeof(PROCESS_MEMORY_COUNTERS_EX);
+
+  if (!GetProcessMemoryInfo(GetCurrentProcess(),
+                            (PPROCESS_MEMORY_COUNTERS) &pmcex, sizeof(pmcex))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  *aN = pmcex.PrivateUsage;
+  return NS_OK;
+}
+
+#define HAVE_SYSTEM_HEAP_REPORTER 1
+// Windows can have multiple separate heaps. During testing there were multiple
+// heaps present but the non-default ones had sizes no more than a few 10s of
+// KiBs. So we combine their sizes into a single measurement.
+static MOZ_MUST_USE nsresult
+SystemHeapSize(int64_t* aSizeOut)
+{
+  // Get the number of heaps.
+  DWORD nHeaps = GetProcessHeaps(0, nullptr);
+  NS_ENSURE_TRUE(nHeaps != 0, NS_ERROR_FAILURE);
+
+  // Get handles to all heaps, checking that the number of heaps hasn't
+  // changed in the meantime.
+  UniquePtr<HANDLE[]> heaps(new HANDLE[nHeaps]);
+  DWORD nHeaps2 = GetProcessHeaps(nHeaps, heaps.get());
+  NS_ENSURE_TRUE(nHeaps2 != 0 && nHeaps2 == nHeaps, NS_ERROR_FAILURE);
+
+  // Lock and iterate over each heap to get its size.
+  int64_t heapsSize = 0;
+  for (DWORD i = 0; i < nHeaps; i++) {
+    HANDLE heap = heaps[i];
+
+    NS_ENSURE_TRUE(HeapLock(heap), NS_ERROR_FAILURE);
+
+    int64_t heapSize = 0;
+    PROCESS_HEAP_ENTRY entry;
+    entry.lpData = nullptr;
+    while (HeapWalk(heap, &entry)) {
+      // We don't count entry.cbOverhead, because we just want to measure the
+      // space available to the program.
+      if (entry.wFlags & PROCESS_HEAP_ENTRY_BUSY) {
+        heapSize += entry.cbData;
+      }
+    }
+
+    // Check this result only after unlocking the heap, so that we don't leave
+    // the heap locked if there was an error.
+    DWORD lastError = GetLastError();
+
+    // I have no idea how things would proceed if unlocking this heap failed...
+    NS_ENSURE_TRUE(HeapUnlock(heap), NS_ERROR_FAILURE);
+
+    NS_ENSURE_TRUE(lastError == ERROR_NO_MORE_ITEMS, NS_ERROR_FAILURE);
+
+    heapsSize += heapSize;
+  }
+
+  *aSizeOut = heapsSize;
+  return NS_OK;
+}
+
+struct SegmentKind
+{
+  DWORD mState;
+  DWORD mType;
+  DWORD mProtect;
+  int mIsStack;
+};
+
+struct SegmentEntry : public PLDHashEntryHdr
+{
+  static PLDHashNumber HashKey(const void* aKey)
+  {
+    auto kind = static_cast<const SegmentKind*>(aKey);
+    return mozilla::HashGeneric(kind->mState, kind->mType, kind->mProtect,
+                                kind->mIsStack);
+  }
+
+  static bool MatchEntry(const PLDHashEntryHdr* aEntry, const void* aKey)
+  {
+    auto kind = static_cast<const SegmentKind*>(aKey);
+    auto entry = static_cast<const SegmentEntry*>(aEntry);
+    return kind->mState == entry->mKind.mState &&
+           kind->mType == entry->mKind.mType &&
+           kind->mProtect == entry->mKind.mProtect &&
+           kind->mIsStack == entry->mKind.mIsStack;
+  }
+
+  static void InitEntry(PLDHashEntryHdr* aEntry, const void* aKey)
+  {
+    auto kind = static_cast<const SegmentKind*>(aKey);
+    auto entry = static_cast<SegmentEntry*>(aEntry);
+    entry->mKind = *kind;
+    entry->mCount = 0;
+    entry->mSize = 0;
+  }
+
+  static const PLDHashTableOps Ops;
+
+  SegmentKind mKind;  // The segment kind.
+  uint32_t mCount;    // The number of segments of this kind.
+  size_t mSize;       // The combined size of segments of this kind.
+};
+
+/* static */ const PLDHashTableOps SegmentEntry::Ops = {
+  SegmentEntry::HashKey,
+  SegmentEntry::MatchEntry,
+  PLDHashTable::MoveEntryStub,
+  PLDHashTable::ClearEntryStub,
+  SegmentEntry::InitEntry
+};
+
+class WindowsAddressSpaceReporter final : public nsIMemoryReporter
+{
+  ~WindowsAddressSpaceReporter() {}
+
+public:
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override
+  {
+    // First iterate over all the segments and record how many of each kind
+    // there were and their aggregate sizes. We use a hash table for this
+    // because there are a couple of dozen different kinds possible.
+
+    PLDHashTable table(&SegmentEntry::Ops, sizeof(SegmentEntry));
+    MEMORY_BASIC_INFORMATION info = { 0 };
+    bool isPrevSegStackGuard = false;
+    for (size_t currentAddress = 0; ; ) {
+      if (!VirtualQuery((LPCVOID)currentAddress, &info, sizeof(info))) {
+        // Something went wrong, just return whatever we've got already.
+        break;
+      }
+
+      size_t size = info.RegionSize;
+
+      // Note that |type| and |protect| are ignored in some cases.
+      DWORD state = info.State;
+      DWORD type =
+        (state == MEM_RESERVE || state == MEM_COMMIT) ? info.Type : 0;
+      DWORD protect = (state == MEM_COMMIT) ? info.Protect : 0;
+      bool isStack = isPrevSegStackGuard &&
+                     state == MEM_COMMIT &&
+                     type == MEM_PRIVATE &&
+                     protect == PAGE_READWRITE;
+
+      SegmentKind kind = { state, type, protect, isStack ? 1 : 0 };
+      auto entry =
+        static_cast<SegmentEntry*>(table.Add(&kind, mozilla::fallible));
+      if (entry) {
+        entry->mCount += 1;
+        entry->mSize += size;
+      }
+
+      isPrevSegStackGuard = info.State == MEM_COMMIT &&
+                            info.Type == MEM_PRIVATE &&
+                            info.Protect == (PAGE_READWRITE|PAGE_GUARD);
+
+      size_t lastAddress = currentAddress;
+      currentAddress += size;
+
+      // If we overflow, we've examined all of the address space.
+      if (currentAddress < lastAddress) {
+        break;
+      }
+    }
+
+    // Then iterate over the hash table and report the details for each segment
+    // kind.
+
+    for (auto iter = table.Iter(); !iter.Done(); iter.Next()) {
+      // For each range of pages, we consider one or more of its State, Type
+      // and Protect values. These are documented at
+      // https://msdn.microsoft.com/en-us/library/windows/desktop/aa366775%28v=vs.85%29.aspx
+      // (for State and Type) and
+      // https://msdn.microsoft.com/en-us/library/windows/desktop/aa366786%28v=vs.85%29.aspx
+      // (for Protect).
+      //
+      // Not all State values have accompanying Type and Protection values.
+      bool doType = false;
+      bool doProtect = false;
+
+      auto entry = static_cast<const SegmentEntry*>(iter.Get());
+
+      nsCString path("address-space");
+
+      switch (entry->mKind.mState) {
+        case MEM_FREE:
+          path.AppendLiteral("/free");
+          break;
+
+        case MEM_RESERVE:
+          path.AppendLiteral("/reserved");
+          doType = true;
+          break;
+
+        case MEM_COMMIT:
+          path.AppendLiteral("/commit");
+          doType = true;
+          doProtect = true;
+          break;
+
+        default:
+          // Should be impossible, but handle it just in case.
+          path.AppendLiteral("/???");
+          break;
+      }
+
+      if (doType) {
+        switch (entry->mKind.mType) {
+          case MEM_IMAGE:
+            path.AppendLiteral("/image");
+            break;
+
+          case MEM_MAPPED:
+            path.AppendLiteral("/mapped");
+            break;
+
+          case MEM_PRIVATE:
+            path.AppendLiteral("/private");
+            break;
+
+          default:
+            // Should be impossible, but handle it just in case.
+            path.AppendLiteral("/???");
+            break;
+        }
+      }
+
+      if (doProtect) {
+        DWORD protect = entry->mKind.mProtect;
+        // Basic attributes. Exactly one of these should be set.
+        if (protect & PAGE_EXECUTE) {
+          path.AppendLiteral("/execute");
+        }
+        if (protect & PAGE_EXECUTE_READ) {
+          path.AppendLiteral("/execute-read");
+        }
+        if (protect & PAGE_EXECUTE_READWRITE) {
+          path.AppendLiteral("/execute-readwrite");
+        }
+        if (protect & PAGE_EXECUTE_WRITECOPY) {
+          path.AppendLiteral("/execute-writecopy");
+        }
+        if (protect & PAGE_NOACCESS) {
+          path.AppendLiteral("/noaccess");
+        }
+        if (protect & PAGE_READONLY) {
+          path.AppendLiteral("/readonly");
+        }
+        if (protect & PAGE_READWRITE) {
+          path.AppendLiteral("/readwrite");
+        }
+        if (protect & PAGE_WRITECOPY) {
+          path.AppendLiteral("/writecopy");
+        }
+
+        // Modifiers. At most one of these should be set.
+        if (protect & PAGE_GUARD) {
+          path.AppendLiteral("+guard");
+        }
+        if (protect & PAGE_NOCACHE) {
+          path.AppendLiteral("+nocache");
+        }
+        if (protect & PAGE_WRITECOMBINE) {
+          path.AppendLiteral("+writecombine");
+        }
+
+        // Annotate likely stack segments, too.
+        if (entry->mKind.mIsStack) {
+          path.AppendLiteral("+stack");
+        }
+      }
+
+      // Append the segment count.
+      path.AppendPrintf("(segments=%u)", entry->mCount);
+
+      aHandleReport->Callback(
+        EmptyCString(), path, KIND_OTHER, UNITS_BYTES, entry->mSize,
+        NS_LITERAL_CSTRING("From MEMORY_BASIC_INFORMATION."), aData);
+    }
+
+    return NS_OK;
+  }
+};
+NS_IMPL_ISUPPORTS(WindowsAddressSpaceReporter, nsIMemoryReporter)
+
+#endif  // XP_<PLATFORM>
+
+#ifdef HAVE_VSIZE_MAX_CONTIGUOUS_REPORTER
+class VsizeMaxContiguousReporter final : public nsIMemoryReporter
+{
+  ~VsizeMaxContiguousReporter() {}
+
+public:
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override
+  {
+    int64_t amount;
+    if (NS_SUCCEEDED(VsizeMaxContiguousDistinguishedAmount(&amount))) {
+      MOZ_COLLECT_REPORT(
+        "vsize-max-contiguous", KIND_OTHER, UNITS_BYTES, amount,
+        "Size of the maximum contiguous block of available virtual memory.");
+    }
+    return NS_OK;
+  }
+};
+NS_IMPL_ISUPPORTS(VsizeMaxContiguousReporter, nsIMemoryReporter)
+#endif
+
+#ifdef HAVE_PRIVATE_REPORTER
+class PrivateReporter final : public nsIMemoryReporter
+{
+  ~PrivateReporter() {}
+
+public:
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override
+  {
+    int64_t amount;
+    if (NS_SUCCEEDED(PrivateDistinguishedAmount(&amount))) {
+      MOZ_COLLECT_REPORT(
+        "private", KIND_OTHER, UNITS_BYTES, amount,
+"Memory that cannot be shared with other processes, including memory that is "
+"committed and marked MEM_PRIVATE, data that is not mapped, and executable "
+"pages that have been written to.");
+    }
+    return NS_OK;
+  }
+};
+NS_IMPL_ISUPPORTS(PrivateReporter, nsIMemoryReporter)
+#endif
+
+#ifdef HAVE_VSIZE_AND_RESIDENT_REPORTERS
+class VsizeReporter final : public nsIMemoryReporter
+{
+  ~VsizeReporter() {}
+
+public:
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override
+  {
+    int64_t amount;
+    if (NS_SUCCEEDED(VsizeDistinguishedAmount(&amount))) {
+      MOZ_COLLECT_REPORT(
+        "vsize", KIND_OTHER, UNITS_BYTES, amount,
+"Memory mapped by the process, including code and data segments, the heap, "
+"thread stacks, memory explicitly mapped by the process via mmap and similar "
+"operations, and memory shared with other processes. This is the vsize figure "
+"as reported by 'top' and 'ps'.  This figure is of limited use on Mac, where "
+"processes share huge amounts of memory with one another.  But even on other "
+"operating systems, 'resident' is a much better measure of the memory "
+"resources used by the process.");
+    }
+    return NS_OK;
+  }
+};
+NS_IMPL_ISUPPORTS(VsizeReporter, nsIMemoryReporter)
+
+class ResidentReporter final : public nsIMemoryReporter
+{
+  ~ResidentReporter() {}
+
+public:
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override
+  {
+    int64_t amount;
+    if (NS_SUCCEEDED(ResidentDistinguishedAmount(&amount))) {
+      MOZ_COLLECT_REPORT(
+        "resident", KIND_OTHER, UNITS_BYTES, amount,
+"Memory mapped by the process that is present in physical memory, also known "
+"as the resident set size (RSS).  This is the best single figure to use when "
+"considering the memory resources used by the process, but it depends both on "
+"other processes being run and details of the OS kernel and so is best used "
+"for comparing the memory usage of a single process at different points in "
+"time.");
+    }
+    return NS_OK;
+  }
+};
+NS_IMPL_ISUPPORTS(ResidentReporter, nsIMemoryReporter)
+
+#endif  // HAVE_VSIZE_AND_RESIDENT_REPORTERS
+
+#ifdef HAVE_RESIDENT_UNIQUE_REPORTER
+class ResidentUniqueReporter final : public nsIMemoryReporter
+{
+  ~ResidentUniqueReporter() {}
+
+public:
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override
+  {
+    int64_t amount = 0;
+    if (NS_SUCCEEDED(ResidentUniqueDistinguishedAmount(&amount))) {
+      MOZ_COLLECT_REPORT(
+        "resident-unique", KIND_OTHER, UNITS_BYTES, amount,
+"Memory mapped by the process that is present in physical memory and not "
+"shared with any other processes.  This is also known as the process's unique "
+"set size (USS).  This is the amount of RAM we'd expect to be freed if we "
+"closed this process.");
+    }
+    return NS_OK;
+  }
+};
+NS_IMPL_ISUPPORTS(ResidentUniqueReporter, nsIMemoryReporter)
+
+#endif // HAVE_RESIDENT_UNIQUE_REPORTER
+
+#ifdef HAVE_SYSTEM_HEAP_REPORTER
+
+class SystemHeapReporter final : public nsIMemoryReporter
+{
+  ~SystemHeapReporter() {}
+
+public:
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override
+  {
+    int64_t amount;
+    if (NS_SUCCEEDED(SystemHeapSize(&amount))) {
+      MOZ_COLLECT_REPORT(
+        "system-heap-allocated", KIND_OTHER, UNITS_BYTES, amount,
+"Memory used by the system allocator that is currently allocated to the "
+"application. This is distinct from the jemalloc heap that Firefox uses for "
+"most or all of its heap allocations. Ideally this number is zero, but "
+"on some platforms we cannot force every heap allocation through jemalloc.");
+    }
+    return NS_OK;
+  }
+};
+NS_IMPL_ISUPPORTS(SystemHeapReporter, nsIMemoryReporter)
+
+#endif // HAVE_SYSTEM_HEAP_REPORTER
+
+#ifdef XP_UNIX
+
+#include <sys/resource.h>
+
+#define HAVE_RESIDENT_PEAK_REPORTER 1
+
+static MOZ_MUST_USE nsresult
+ResidentPeakDistinguishedAmount(int64_t* aN)
+{
+  struct rusage usage;
+  if (0 == getrusage(RUSAGE_SELF, &usage)) {
+    // The units for ru_maxrrs:
+    // - Mac: bytes
+    // - Solaris: pages? But some sources it actually always returns 0, so
+    //   check for that
+    // - Linux, {Net/Open/Free}BSD, DragonFly: KiB
+#ifdef XP_MACOSX
+    *aN = usage.ru_maxrss;
+#elif defined(SOLARIS)
+    *aN = usage.ru_maxrss * getpagesize();
+#else
+    *aN = usage.ru_maxrss * 1024;
+#endif
+    if (*aN > 0) {
+      return NS_OK;
+    }
+  }
+  return NS_ERROR_FAILURE;
+}
+
+class ResidentPeakReporter final : public nsIMemoryReporter
+{
+  ~ResidentPeakReporter() {}
+
+public:
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override
+  {
+    int64_t amount = 0;
+    if (NS_SUCCEEDED(ResidentPeakDistinguishedAmount(&amount))) {
+      MOZ_COLLECT_REPORT(
+        "resident-peak", KIND_OTHER, UNITS_BYTES, amount,
+"The peak 'resident' value for the lifetime of the process.");
+    }
+    return NS_OK;
+  }
+};
+NS_IMPL_ISUPPORTS(ResidentPeakReporter, nsIMemoryReporter)
+
+#define HAVE_PAGE_FAULT_REPORTERS 1
+
+class PageFaultsSoftReporter final : public nsIMemoryReporter
+{
+  ~PageFaultsSoftReporter() {}
+
+public:
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override
+  {
+    struct rusage usage;
+    int err = getrusage(RUSAGE_SELF, &usage);
+    if (err == 0) {
+      int64_t amount = usage.ru_minflt;
+      MOZ_COLLECT_REPORT(
+        "page-faults-soft", KIND_OTHER, UNITS_COUNT_CUMULATIVE, amount,
+"The number of soft page faults (also known as 'minor page faults') that "
+"have occurred since the process started.  A soft page fault occurs when the "
+"process tries to access a page which is present in physical memory but is "
+"not mapped into the process's address space.  For instance, a process might "
+"observe soft page faults when it loads a shared library which is already "
+"present in physical memory. A process may experience many thousands of soft "
+"page faults even when the machine has plenty of available physical memory, "
+"and because the OS services a soft page fault without accessing the disk, "
+"they impact performance much less than hard page faults.");
+    }
+    return NS_OK;
+  }
+};
+NS_IMPL_ISUPPORTS(PageFaultsSoftReporter, nsIMemoryReporter)
+
+static MOZ_MUST_USE nsresult
+PageFaultsHardDistinguishedAmount(int64_t* aAmount)
+{
+  struct rusage usage;
+  int err = getrusage(RUSAGE_SELF, &usage);
+  if (err != 0) {
+    return NS_ERROR_FAILURE;
+  }
+  *aAmount = usage.ru_majflt;
+  return NS_OK;
+}
+
+class PageFaultsHardReporter final : public nsIMemoryReporter
+{
+  ~PageFaultsHardReporter() {}
+
+public:
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override
+  {
+    int64_t amount = 0;
+    if (NS_SUCCEEDED(PageFaultsHardDistinguishedAmount(&amount))) {
+      MOZ_COLLECT_REPORT(
+        "page-faults-hard", KIND_OTHER, UNITS_COUNT_CUMULATIVE, amount,
+"The number of hard page faults (also known as 'major page faults') that have "
+"occurred since the process started.  A hard page fault occurs when a process "
+"tries to access a page which is not present in physical memory. The "
+"operating system must access the disk in order to fulfill a hard page fault. "
+"When memory is plentiful, you should see very few hard page faults. But if "
+"the process tries to use more memory than your machine has available, you "
+"may see many thousands of hard page faults. Because accessing the disk is up "
+"to a million times slower than accessing RAM, the program may run very "
+"slowly when it is experiencing more than 100 or so hard page faults a "
+"second.");
+    }
+    return NS_OK;
+  }
+};
+NS_IMPL_ISUPPORTS(PageFaultsHardReporter, nsIMemoryReporter)
+
+#endif  // XP_UNIX
+
+/**
+ ** memory reporter implementation for jemalloc and OSX malloc,
+ ** to obtain info on total memory in use (that we know about,
+ ** at least -- on OSX, there are sometimes other zones in use).
+ **/
+
+#ifdef HAVE_JEMALLOC_STATS
+
+static size_t
+HeapOverhead(jemalloc_stats_t* aStats)
+{
+  return aStats->waste + aStats->bookkeeping +
+         aStats->page_cache + aStats->bin_unused;
+}
+
+// This has UNITS_PERCENTAGE, so it is multiplied by 100x *again* on top of the
+// 100x for the percentage.
+static int64_t
+HeapOverheadFraction(jemalloc_stats_t* aStats)
+{
+  size_t heapOverhead = HeapOverhead(aStats);
+  size_t heapCommitted = aStats->allocated + heapOverhead;
+  return int64_t(10000 * (heapOverhead / (double)heapCommitted));
+}
+
+class JemallocHeapReporter final : public nsIMemoryReporter
+{
+  ~JemallocHeapReporter() {}
+
+public:
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override
+  {
+    jemalloc_stats_t stats;
+    jemalloc_stats(&stats);
+
+    MOZ_COLLECT_REPORT(
+      "heap-committed/allocated", KIND_OTHER, UNITS_BYTES, stats.allocated,
+"Memory mapped by the heap allocator that is currently allocated to the "
+"application.  This may exceed the amount of memory requested by the "
+"application because the allocator regularly rounds up request sizes. (The "
+"exact amount requested is not recorded.)");
+
+    MOZ_COLLECT_REPORT(
+      "heap-allocated", KIND_OTHER, UNITS_BYTES, stats.allocated,
+"The same as 'heap-committed/allocated'.");
+
+    // We mark this and the other heap-overhead reporters as KIND_NONHEAP
+    // because KIND_HEAP memory means "counted in heap-allocated", which
+    // this is not.
+    MOZ_COLLECT_REPORT(
+      "explicit/heap-overhead/bin-unused", KIND_NONHEAP, UNITS_BYTES,
+      stats.bin_unused,
+"Unused bytes due to fragmentation in the bins used for 'small' (<= 2 KiB) "
+"allocations. These bytes will be used if additional allocations occur.");
+
+    if (stats.waste > 0) {
+      MOZ_COLLECT_REPORT(
+        "explicit/heap-overhead/waste", KIND_NONHEAP, UNITS_BYTES,
+        stats.waste,
+"Committed bytes which do not correspond to an active allocation and which the "
+"allocator is not intentionally keeping alive (i.e., not "
+"'explicit/heap-overhead/{bookkeeping,page-cache,bin-unused}').");
+    }
+
+    MOZ_COLLECT_REPORT(
+      "explicit/heap-overhead/bookkeeping", KIND_NONHEAP, UNITS_BYTES,
+      stats.bookkeeping,
+"Committed bytes which the heap allocator uses for internal data structures.");
+
+    MOZ_COLLECT_REPORT(
+      "explicit/heap-overhead/page-cache", KIND_NONHEAP, UNITS_BYTES,
+      stats.page_cache,
+"Memory which the allocator could return to the operating system, but hasn't. "
+"The allocator keeps this memory around as an optimization, so it doesn't "
+"have to ask the OS the next time it needs to fulfill a request. This value "
+"is typically not larger than a few megabytes.");
+
+    MOZ_COLLECT_REPORT(
+      "heap-committed/overhead", KIND_OTHER, UNITS_BYTES,
+      HeapOverhead(&stats),
+"The sum of 'explicit/heap-overhead/*'.");
+
+    MOZ_COLLECT_REPORT(
+      "heap-mapped", KIND_OTHER, UNITS_BYTES, stats.mapped,
+"Amount of memory currently mapped. Includes memory that is uncommitted, i.e. "
+"neither in physical memory nor paged to disk.");
+
+    MOZ_COLLECT_REPORT(
+      "heap-chunksize", KIND_OTHER, UNITS_BYTES, stats.chunksize,
+      "Size of chunks.");
+
+    return NS_OK;
+  }
+};
+NS_IMPL_ISUPPORTS(JemallocHeapReporter, nsIMemoryReporter)
+
+#endif  // HAVE_JEMALLOC_STATS
+
+// Why is this here?  At first glance, you'd think it could be defined and
+// registered with nsMemoryReporterManager entirely within nsAtomTable.cpp.
+// However, the obvious time to register it is when the table is initialized,
+// and that happens before XPCOM components are initialized, which means the
+// RegisterStrongMemoryReporter call fails.  So instead we do it here.
+class AtomTablesReporter final : public nsIMemoryReporter
+{
+  MOZ_DEFINE_MALLOC_SIZE_OF(MallocSizeOf)
+
+  ~AtomTablesReporter() {}
+
+public:
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override
+  {
+    size_t Main, Static;
+    NS_SizeOfAtomTablesIncludingThis(MallocSizeOf, &Main, &Static);
+
+    MOZ_COLLECT_REPORT(
+      "explicit/atom-tables/main", KIND_HEAP, UNITS_BYTES, Main,
+      "Memory used by the main atoms table.");
+
+    MOZ_COLLECT_REPORT(
+      "explicit/atom-tables/static", KIND_HEAP, UNITS_BYTES, Static,
+      "Memory used by the static atoms table.");
+
+    return NS_OK;
+  }
+};
+NS_IMPL_ISUPPORTS(AtomTablesReporter, nsIMemoryReporter)
+
+#ifdef DEBUG
+
+// Ideally, this would be implemented in BlockingResourceBase.cpp.
+// However, this ends up breaking the linking step of various unit tests due
+// to adding a new dependency to libdmd for a commonly used feature (mutexes)
+// in  DMD  builds. So instead we do it here.
+class DeadlockDetectorReporter final : public nsIMemoryReporter
+{
+  MOZ_DEFINE_MALLOC_SIZE_OF(MallocSizeOf)
+
+  ~DeadlockDetectorReporter() {}
+
+public:
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override
+  {
+    MOZ_COLLECT_REPORT(
+      "explicit/deadlock-detector", KIND_HEAP, UNITS_BYTES,
+      BlockingResourceBase::SizeOfDeadlockDetector(MallocSizeOf),
+      "Memory used by the deadlock detector.");
+
+    return NS_OK;
+  }
+};
+NS_IMPL_ISUPPORTS(DeadlockDetectorReporter, nsIMemoryReporter)
+
+#endif
+
+#ifdef MOZ_DMD
+
+namespace mozilla {
+namespace dmd {
+
+class DMDReporter final : public nsIMemoryReporter
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override
+  {
+    dmd::Sizes sizes;
+    dmd::SizeOf(&sizes);
+
+    MOZ_COLLECT_REPORT(
+      "explicit/dmd/stack-traces/used", KIND_HEAP, UNITS_BYTES,
+      sizes.mStackTracesUsed,
+      "Memory used by stack traces which correspond to at least "
+      "one heap block DMD is tracking.");
+
+    MOZ_COLLECT_REPORT(
+      "explicit/dmd/stack-traces/unused", KIND_HEAP, UNITS_BYTES,
+      sizes.mStackTracesUnused,
+      "Memory used by stack traces which don't correspond to any heap "
+      "blocks DMD is currently tracking.");
+
+    MOZ_COLLECT_REPORT(
+      "explicit/dmd/stack-traces/table", KIND_HEAP, UNITS_BYTES,
+      sizes.mStackTraceTable,
+      "Memory used by DMD's stack trace table.");
+
+    MOZ_COLLECT_REPORT(
+      "explicit/dmd/live-block-table", KIND_HEAP, UNITS_BYTES,
+      sizes.mLiveBlockTable,
+      "Memory used by DMD's live block table.");
+
+    MOZ_COLLECT_REPORT(
+      "explicit/dmd/dead-block-list", KIND_HEAP, UNITS_BYTES,
+      sizes.mDeadBlockTable,
+      "Memory used by DMD's dead block list.");
+
+    return NS_OK;
+  }
+
+private:
+  ~DMDReporter() {}
+};
+NS_IMPL_ISUPPORTS(DMDReporter, nsIMemoryReporter)
+
+} // namespace dmd
+} // namespace mozilla
+
+#endif  // MOZ_DMD
+
+/**
+ ** nsMemoryReporterManager implementation
+ **/
+
+NS_IMPL_ISUPPORTS(nsMemoryReporterManager, nsIMemoryReporterManager)
+
+NS_IMETHODIMP
+nsMemoryReporterManager::Init()
+{
+  if (!NS_IsMainThread()) {
+    MOZ_CRASH();
+  }
+
+  // Under normal circumstances this function is only called once. However,
+  // we've (infrequently) seen memory report dumps in crash reports that
+  // suggest that this function is sometimes called multiple times. That in
+  // turn means that multiple reporters of each kind are registered, which
+  // leads to duplicated reports of individual measurements such as "resident",
+  // "vsize", etc.
+  //
+  // It's unclear how these multiple calls can occur. The only plausible theory
+  // so far is badly-written extensions, because this function is callable from
+  // JS code via nsIMemoryReporter.idl.
+  //
+  // Whatever the cause, it's a bad thing. So we protect against it with the
+  // following check.
+  static bool isInited = false;
+  if (isInited) {
+    NS_WARNING("nsMemoryReporterManager::Init() has already been called!");
+    return NS_OK;
+  }
+  isInited = true;
+
+#if defined(HAVE_JEMALLOC_STATS) && defined(MOZ_GLUE_IN_PROGRAM)
+  if (!jemalloc_stats) {
+    return NS_ERROR_FAILURE;
+  }
+#endif
+
+#ifdef HAVE_JEMALLOC_STATS
+  RegisterStrongReporter(new JemallocHeapReporter());
+#endif
+
+#ifdef HAVE_VSIZE_AND_RESIDENT_REPORTERS
+  RegisterStrongReporter(new VsizeReporter());
+  RegisterStrongReporter(new ResidentReporter());
+#endif
+
+#ifdef HAVE_VSIZE_MAX_CONTIGUOUS_REPORTER
+  RegisterStrongReporter(new VsizeMaxContiguousReporter());
+#endif
+
+#ifdef HAVE_RESIDENT_PEAK_REPORTER
+  RegisterStrongReporter(new ResidentPeakReporter());
+#endif
+
+#ifdef HAVE_RESIDENT_UNIQUE_REPORTER
+  RegisterStrongReporter(new ResidentUniqueReporter());
+#endif
+
+#ifdef HAVE_PAGE_FAULT_REPORTERS
+  RegisterStrongReporter(new PageFaultsSoftReporter());
+  RegisterStrongReporter(new PageFaultsHardReporter());
+#endif
+
+#ifdef HAVE_PRIVATE_REPORTER
+  RegisterStrongReporter(new PrivateReporter());
+#endif
+
+#ifdef HAVE_SYSTEM_HEAP_REPORTER
+  RegisterStrongReporter(new SystemHeapReporter());
+#endif
+
+  RegisterStrongReporter(new AtomTablesReporter());
+
+#ifdef DEBUG
+  RegisterStrongReporter(new DeadlockDetectorReporter());
+#endif
+
+#ifdef MOZ_DMD
+  RegisterStrongReporter(new mozilla::dmd::DMDReporter());
+#endif
+
+#ifdef XP_WIN
+  RegisterStrongReporter(new WindowsAddressSpaceReporter());
+#endif
+
+#ifdef XP_UNIX
+  nsMemoryInfoDumper::Initialize();
+#endif
+
+  return NS_OK;
+}
+
+nsMemoryReporterManager::nsMemoryReporterManager()
+  : mMutex("nsMemoryReporterManager::mMutex")
+  , mIsRegistrationBlocked(false)
+  , mStrongReporters(new StrongReportersTable())
+  , mWeakReporters(new WeakReportersTable())
+  , mSavedStrongReporters(nullptr)
+  , mSavedWeakReporters(nullptr)
+  , mNextGeneration(1)
+  , mPendingProcessesState(nullptr)
+  , mPendingReportersState(nullptr)
+{
+}
+
+nsMemoryReporterManager::~nsMemoryReporterManager()
+{
+  delete mStrongReporters;
+  delete mWeakReporters;
+  NS_ASSERTION(!mSavedStrongReporters, "failed to restore strong reporters");
+  NS_ASSERTION(!mSavedWeakReporters, "failed to restore weak reporters");
+}
+
+#ifdef MOZ_WIDGET_GONK
+#define DEBUG_CHILD_PROCESS_MEMORY_REPORTING 1
+#endif
+
+#ifdef DEBUG_CHILD_PROCESS_MEMORY_REPORTING
+#define MEMORY_REPORTING_LOG(format, ...) \
+  printf_stderr("++++ MEMORY REPORTING: " format, ##__VA_ARGS__);
+#else
+#define MEMORY_REPORTING_LOG(...)
+#endif
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetReports(
+  nsIHandleReportCallback* aHandleReport,
+  nsISupports* aHandleReportData,
+  nsIFinishReportingCallback* aFinishReporting,
+  nsISupports* aFinishReportingData,
+  bool aAnonymize)
+{
+  return GetReportsExtended(aHandleReport, aHandleReportData,
+                            aFinishReporting, aFinishReportingData,
+                            aAnonymize,
+                            /* minimize = */ false,
+                            /* DMDident = */ EmptyString());
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetReportsExtended(
+  nsIHandleReportCallback* aHandleReport,
+  nsISupports* aHandleReportData,
+  nsIFinishReportingCallback* aFinishReporting,
+  nsISupports* aFinishReportingData,
+  bool aAnonymize,
+  bool aMinimize,
+  const nsAString& aDMDDumpIdent)
+{
+  nsresult rv;
+
+  // Memory reporters are not necessarily threadsafe, so this function must
+  // be called from the main thread.
+  if (!NS_IsMainThread()) {
+    MOZ_CRASH();
+  }
+
+  uint32_t generation = mNextGeneration++;
+
+  if (mPendingProcessesState) {
+    // A request is in flight.  Don't start another one.  And don't report
+    // an error;  just ignore it, and let the in-flight request finish.
+    MEMORY_REPORTING_LOG("GetReports (gen=%u, s->gen=%u): abort\n",
+                         generation, mPendingProcessesState->mGeneration);
+    return NS_OK;
+  }
+
+  MEMORY_REPORTING_LOG("GetReports (gen=%u)\n", generation);
+
+  uint32_t concurrency = Preferences::GetUint("memory.report_concurrency", 1);
+  MOZ_ASSERT(concurrency >= 1);
+  if (concurrency < 1) {
+    concurrency = 1;
+  }
+  mPendingProcessesState = new PendingProcessesState(generation,
+                                                     aAnonymize,
+                                                     aMinimize,
+                                                     concurrency,
+                                                     aHandleReport,
+                                                     aHandleReportData,
+                                                     aFinishReporting,
+                                                     aFinishReportingData,
+                                                     aDMDDumpIdent);
+
+  if (aMinimize) {
+    nsCOMPtr<nsIRunnable> callback =
+      NewRunnableMethod(this, &nsMemoryReporterManager::StartGettingReports);
+    rv = MinimizeMemoryUsage(callback);
+  } else {
+    rv = StartGettingReports();
+  }
+  return rv;
+}
+
+nsresult
+nsMemoryReporterManager::StartGettingReports()
+{
+  PendingProcessesState* s = mPendingProcessesState;
+  nsresult rv;
+
+  // Get reports for this process.
+  FILE* parentDMDFile = nullptr;
+#ifdef MOZ_DMD
+  if (!s->mDMDDumpIdent.IsEmpty()) {
+    rv = nsMemoryInfoDumper::OpenDMDFile(s->mDMDDumpIdent, getpid(),
+                                                  &parentDMDFile);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      // Proceed with the memory report as if DMD were disabled.
+      parentDMDFile = nullptr;
+    }
+  }
+#endif
+
+  // This is async.
+  GetReportsForThisProcessExtended(s->mHandleReport, s->mHandleReportData,
+                                   s->mAnonymize, parentDMDFile,
+                                   s->mFinishReporting, s->mFinishReportingData);
+
+  nsTArray<ContentParent*> childWeakRefs;
+  ContentParent::GetAll(childWeakRefs);
+  if (!childWeakRefs.IsEmpty()) {
+    // Request memory reports from child processes.  This happens
+    // after the parent report so that the parent's main thread will
+    // be free to process the child reports, instead of causing them
+    // to be buffered and consume (possibly scarce) memory.
+
+    for (size_t i = 0; i < childWeakRefs.Length(); ++i) {
+      s->mChildrenPending.AppendElement(childWeakRefs[i]);
+    }
+
+    nsCOMPtr<nsITimer> timer = do_CreateInstance(NS_TIMER_CONTRACTID);
+    // Don't use NS_ENSURE_* here; can't return until the report is finished.
+    if (NS_WARN_IF(!timer)) {
+      FinishReporting();
+      return NS_ERROR_FAILURE;
+    }
+    rv = timer->InitWithFuncCallback(TimeoutCallback,
+                                     this, kTimeoutLengthMS,
+                                     nsITimer::TYPE_ONE_SHOT);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      FinishReporting();
+      return rv;
+    }
+
+    MOZ_ASSERT(!s->mTimer);
+    s->mTimer.swap(timer);
+  }
+
+  return NS_OK;
+}
+
+void
+nsMemoryReporterManager::DispatchReporter(
+  nsIMemoryReporter* aReporter, bool aIsAsync,
+  nsIHandleReportCallback* aHandleReport,
+  nsISupports* aHandleReportData,
+  bool aAnonymize)
+{
+  MOZ_ASSERT(mPendingReportersState);
+
+  // Grab refs to everything used in the lambda function.
+  RefPtr<nsMemoryReporterManager> self = this;
+  nsCOMPtr<nsIMemoryReporter> reporter = aReporter;
+  nsCOMPtr<nsIHandleReportCallback> handleReport = aHandleReport;
+  nsCOMPtr<nsISupports> handleReportData = aHandleReportData;
+
+  nsCOMPtr<nsIRunnable> event = NS_NewRunnableFunction(
+    [self, reporter, aIsAsync, handleReport, handleReportData, aAnonymize] () {
+      reporter->CollectReports(handleReport, handleReportData, aAnonymize);
+      if (!aIsAsync) {
+        self->EndReport();
+      }
+    });
+
+  NS_DispatchToMainThread(event);
+  mPendingReportersState->mReportsPending++;
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetReportsForThisProcessExtended(
+  nsIHandleReportCallback* aHandleReport, nsISupports* aHandleReportData,
+  bool aAnonymize, FILE* aDMDFile,
+  nsIFinishReportingCallback* aFinishReporting,
+  nsISupports* aFinishReportingData)
+{
+  // Memory reporters are not necessarily threadsafe, so this function must
+  // be called from the main thread.
+  if (!NS_IsMainThread()) {
+    MOZ_CRASH();
+  }
+
+  if (NS_WARN_IF(mPendingReportersState)) {
+    // Report is already in progress.
+    return NS_ERROR_IN_PROGRESS;
+  }
+
+#ifdef MOZ_DMD
+  if (aDMDFile) {
+    // Clear DMD's reportedness state before running the memory
+    // reporters, to avoid spurious twice-reported warnings.
+    dmd::ClearReports();
+  }
+#else
+  MOZ_ASSERT(!aDMDFile);
+#endif
+
+  mPendingReportersState = new PendingReportersState(
+      aFinishReporting, aFinishReportingData, aDMDFile);
+
+  {
+    mozilla::MutexAutoLock autoLock(mMutex);
+
+    for (auto iter = mStrongReporters->Iter(); !iter.Done(); iter.Next()) {
+      DispatchReporter(iter.Key(), iter.Data(),
+                       aHandleReport, aHandleReportData, aAnonymize);
+    }
+
+    for (auto iter = mWeakReporters->Iter(); !iter.Done(); iter.Next()) {
+      nsCOMPtr<nsIMemoryReporter> reporter = iter.Key();
+      DispatchReporter(reporter, iter.Data(),
+                       aHandleReport, aHandleReportData, aAnonymize);
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::EndReport()
+{
+  if (--mPendingReportersState->mReportsPending == 0) {
+#ifdef MOZ_DMD
+    if (mPendingReportersState->mDMDFile) {
+      nsMemoryInfoDumper::DumpDMDToFile(mPendingReportersState->mDMDFile);
+    }
+#endif
+    if (mPendingProcessesState) {
+      // This is the parent process.
+      EndProcessReport(mPendingProcessesState->mGeneration, true);
+    } else {
+      mPendingReportersState->mFinishReporting->Callback(
+          mPendingReportersState->mFinishReportingData);
+    }
+
+    delete mPendingReportersState;
+    mPendingReportersState = nullptr;
+  }
+
+  return NS_OK;
+}
+
+nsMemoryReporterManager::PendingProcessesState*
+nsMemoryReporterManager::GetStateForGeneration(uint32_t aGeneration)
+{
+  // Memory reporting only happens on the main thread.
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+
+  PendingProcessesState* s = mPendingProcessesState;
+
+  if (!s) {
+    // If we reach here, then:
+    //
+    // - A child process reported back too late, and no subsequent request
+    //   is in flight.
+    //
+    // So there's nothing to be done.  Just ignore it.
+    MEMORY_REPORTING_LOG(
+      "HandleChildReports: no request in flight (aGen=%u)\n",
+      aGeneration);
+    return nullptr;
+  }
+
+  if (aGeneration != s->mGeneration) {
+    // If we reach here, a child process must have reported back, too late,
+    // while a subsequent (higher-numbered) request is in flight.  Again,
+    // ignore it.
+    MOZ_ASSERT(aGeneration < s->mGeneration);
+    MEMORY_REPORTING_LOG(
+      "HandleChildReports: gen mismatch (aGen=%u, s->gen=%u)\n",
+      aGeneration, s->mGeneration);
+    return nullptr;
+  }
+
+  return s;
+}
+
+// This function has no return value.  If something goes wrong, there's no
+// clear place to report the problem to, but that's ok -- we will end up
+// hitting the timeout and executing TimeoutCallback().
+void
+nsMemoryReporterManager::HandleChildReport(
+  uint32_t aGeneration,
+  const dom::MemoryReport& aChildReport)
+{
+  PendingProcessesState* s = GetStateForGeneration(aGeneration);
+  if (!s) {
+    return;
+  }
+
+  // Child reports should have a non-empty process.
+  MOZ_ASSERT(!aChildReport.process().IsEmpty());
+
+  // If the call fails, ignore and continue.
+  s->mHandleReport->Callback(aChildReport.process(),
+                             aChildReport.path(),
+                             aChildReport.kind(),
+                             aChildReport.units(),
+                             aChildReport.amount(),
+                             aChildReport.desc(),
+                             s->mHandleReportData);
+}
+
+/* static */ bool
+nsMemoryReporterManager::StartChildReport(mozilla::dom::ContentParent* aChild,
+                                          const PendingProcessesState* aState)
+{
+  if (!aChild->IsAlive()) {
+    MEMORY_REPORTING_LOG("StartChildReports (gen=%u): child exited before"
+                         " its report was started\n",
+                         aState->mGeneration);
+    return false;
+  }
+
+  mozilla::dom::MaybeFileDesc dmdFileDesc = void_t();
+#ifdef MOZ_DMD
+  if (!aState->mDMDDumpIdent.IsEmpty()) {
+    FILE *dmdFile = nullptr;
+    nsresult rv = nsMemoryInfoDumper::OpenDMDFile(aState->mDMDDumpIdent,
+                                                  aChild->Pid(), &dmdFile);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      // Proceed with the memory report as if DMD were disabled.
+      dmdFile = nullptr;
+    }
+    if (dmdFile) {
+      dmdFileDesc = mozilla::ipc::FILEToFileDescriptor(dmdFile);
+      fclose(dmdFile);
+    }
+  }
+#endif
+  return aChild->SendPMemoryReportRequestConstructor(
+    aState->mGeneration, aState->mAnonymize, aState->mMinimize, dmdFileDesc);
+}
+
+void
+nsMemoryReporterManager::EndProcessReport(uint32_t aGeneration, bool aSuccess)
+{
+  PendingProcessesState* s = GetStateForGeneration(aGeneration);
+  if (!s) {
+    return;
+  }
+
+  MOZ_ASSERT(s->mNumProcessesRunning > 0);
+  s->mNumProcessesRunning--;
+  s->mNumProcessesCompleted++;
+  MEMORY_REPORTING_LOG("HandleChildReports (aGen=%u): process %u %s"
+                       " (%u running, %u pending)\n",
+                       aGeneration, s->mNumProcessesCompleted,
+                       aSuccess ? "completed" : "exited during report",
+                       s->mNumProcessesRunning,
+                       static_cast<unsigned>(s->mChildrenPending.Length()));
+
+  // Start pending children up to the concurrency limit.
+  while (s->mNumProcessesRunning < s->mConcurrencyLimit &&
+         !s->mChildrenPending.IsEmpty()) {
+    // Pop last element from s->mChildrenPending
+    RefPtr<ContentParent> nextChild;
+    nextChild.swap(s->mChildrenPending.LastElement());
+    s->mChildrenPending.TruncateLength(s->mChildrenPending.Length() - 1);
+    // Start report (if the child is still alive).
+    if (StartChildReport(nextChild, s)) {
+      ++s->mNumProcessesRunning;
+      MEMORY_REPORTING_LOG("HandleChildReports (aGen=%u): started child report"
+                           " (%u running, %u pending)\n",
+                           aGeneration, s->mNumProcessesRunning,
+                           static_cast<unsigned>(s->mChildrenPending.Length()));
+    }
+  }
+
+  // If all the child processes (if any) have reported, we can cancel
+  // the timer (if started) and finish up.  Otherwise, just return.
+  if (s->mNumProcessesRunning == 0) {
+    MOZ_ASSERT(s->mChildrenPending.IsEmpty());
+    if (s->mTimer) {
+      s->mTimer->Cancel();
+    }
+    FinishReporting();
+  }
+}
+
+/* static */ void
+nsMemoryReporterManager::TimeoutCallback(nsITimer* aTimer, void* aData)
+{
+  nsMemoryReporterManager* mgr = static_cast<nsMemoryReporterManager*>(aData);
+  PendingProcessesState* s = mgr->mPendingProcessesState;
+
+  // Release assert because: if the pointer is null we're about to
+  // crash regardless of DEBUG, and this way the compiler doesn't
+  // complain about unused variables.
+  MOZ_RELEASE_ASSERT(s, "mgr->mPendingProcessesState");
+  MEMORY_REPORTING_LOG("TimeoutCallback (s->gen=%u; %u running, %u pending)\n",
+                       s->mGeneration, s->mNumProcessesRunning,
+                       static_cast<unsigned>(s->mChildrenPending.Length()));
+
+  // We don't bother sending any kind of cancellation message to the child
+  // processes that haven't reported back.
+  mgr->FinishReporting();
+}
+
+nsresult
+nsMemoryReporterManager::FinishReporting()
+{
+  // Memory reporting only happens on the main thread.
+  if (!NS_IsMainThread()) {
+    MOZ_CRASH();
+  }
+
+  MOZ_ASSERT(mPendingProcessesState);
+  MEMORY_REPORTING_LOG("FinishReporting (s->gen=%u; %u processes reported)\n",
+                       mPendingProcessesState->mGeneration,
+                       mPendingProcessesState->mNumProcessesCompleted);
+
+  // Call this before deleting |mPendingProcessesState|.  That way, if
+  // |mFinishReportData| calls GetReports(), it will silently abort, as
+  // required.
+  nsresult rv = mPendingProcessesState->mFinishReporting->Callback(
+    mPendingProcessesState->mFinishReportingData);
+
+  delete mPendingProcessesState;
+  mPendingProcessesState = nullptr;
+  return rv;
+}
+
+nsMemoryReporterManager::PendingProcessesState::PendingProcessesState(
+    uint32_t aGeneration, bool aAnonymize, bool aMinimize,
+    uint32_t aConcurrencyLimit,
+    nsIHandleReportCallback* aHandleReport,
+    nsISupports* aHandleReportData,
+    nsIFinishReportingCallback* aFinishReporting,
+    nsISupports* aFinishReportingData,
+    const nsAString& aDMDDumpIdent)
+  : mGeneration(aGeneration)
+  , mAnonymize(aAnonymize)
+  , mMinimize(aMinimize)
+  , mChildrenPending()
+  , mNumProcessesRunning(1) // reporting starts with the parent
+  , mNumProcessesCompleted(0)
+  , mConcurrencyLimit(aConcurrencyLimit)
+  , mHandleReport(aHandleReport)
+  , mHandleReportData(aHandleReportData)
+  , mFinishReporting(aFinishReporting)
+  , mFinishReportingData(aFinishReportingData)
+  , mDMDDumpIdent(aDMDDumpIdent)
+{
+}
+
+static void
+CrashIfRefcountIsZero(nsISupports* aObj)
+{
+  // This will probably crash if the object's refcount is 0.
+  uint32_t refcnt = NS_ADDREF(aObj);
+  if (refcnt <= 1) {
+    MOZ_CRASH("CrashIfRefcountIsZero: refcount is zero");
+  }
+  NS_RELEASE(aObj);
+}
+
+nsresult
+nsMemoryReporterManager::RegisterReporterHelper(
+  nsIMemoryReporter* aReporter, bool aForce, bool aStrong, bool aIsAsync)
+{
+  // This method is thread-safe.
+  mozilla::MutexAutoLock autoLock(mMutex);
+
+  if (mIsRegistrationBlocked && !aForce) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (mStrongReporters->Contains(aReporter) ||
+      mWeakReporters->Contains(aReporter)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // If |aStrong| is true, |aReporter| may have a refcnt of 0, so we take
+  // a kung fu death grip before calling PutEntry.  Otherwise, if PutEntry
+  // addref'ed and released |aReporter| before finally addref'ing it for
+  // good, it would free aReporter!  The kung fu death grip could itself be
+  // problematic if PutEntry didn't addref |aReporter| (because then when the
+  // death grip goes out of scope, we would delete the reporter).  In debug
+  // mode, we check that this doesn't happen.
+  //
+  // If |aStrong| is false, we require that |aReporter| have a non-zero
+  // refcnt.
+  //
+  if (aStrong) {
+    nsCOMPtr<nsIMemoryReporter> kungFuDeathGrip = aReporter;
+    mStrongReporters->Put(aReporter, aIsAsync);
+    CrashIfRefcountIsZero(aReporter);
+  } else {
+    CrashIfRefcountIsZero(aReporter);
+    nsCOMPtr<nsIXPConnectWrappedJS> jsComponent = do_QueryInterface(aReporter);
+    if (jsComponent) {
+      // We cannot allow non-native reporters (WrappedJS), since we'll be
+      // holding onto a raw pointer, which would point to the wrapper,
+      // and that wrapper is likely to go away as soon as this register
+      // call finishes.  This would then lead to subsequent crashes in
+      // CollectReports().
+      return NS_ERROR_XPC_BAD_CONVERT_JS;
+    }
+    mWeakReporters->Put(aReporter, aIsAsync);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::RegisterStrongReporter(nsIMemoryReporter* aReporter)
+{
+  return RegisterReporterHelper(aReporter, /* force = */ false,
+                                /* strong = */ true,
+                                /* async = */ false);
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::RegisterStrongAsyncReporter(nsIMemoryReporter* aReporter)
+{
+  return RegisterReporterHelper(aReporter, /* force = */ false,
+                                /* strong = */ true,
+                                /* async = */ true);
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::RegisterWeakReporter(nsIMemoryReporter* aReporter)
+{
+  return RegisterReporterHelper(aReporter, /* force = */ false,
+                                /* strong = */ false,
+                                /* async = */ false);
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::RegisterWeakAsyncReporter(nsIMemoryReporter* aReporter)
+{
+  return RegisterReporterHelper(aReporter, /* force = */ false,
+                                /* strong = */ false,
+                                /* async = */ true);
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::RegisterStrongReporterEvenIfBlocked(
+  nsIMemoryReporter* aReporter)
+{
+  return RegisterReporterHelper(aReporter, /* force = */ true,
+                                /* strong = */ true,
+                                /* async = */ false);
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::UnregisterStrongReporter(nsIMemoryReporter* aReporter)
+{
+  // This method is thread-safe.
+  mozilla::MutexAutoLock autoLock(mMutex);
+
+  MOZ_ASSERT(!mWeakReporters->Contains(aReporter));
+
+  if (mStrongReporters->Contains(aReporter)) {
+    mStrongReporters->Remove(aReporter);
+    return NS_OK;
+  }
+
+  // We don't register new reporters when the block is in place, but we do
+  // unregister existing reporters. This is so we don't keep holding strong
+  // references that these reporters aren't expecting (which can keep them
+  // alive longer than intended).
+  if (mSavedStrongReporters && mSavedStrongReporters->Contains(aReporter)) {
+    mSavedStrongReporters->Remove(aReporter);
+    return NS_OK;
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::UnregisterWeakReporter(nsIMemoryReporter* aReporter)
+{
+  // This method is thread-safe.
+  mozilla::MutexAutoLock autoLock(mMutex);
+
+  MOZ_ASSERT(!mStrongReporters->Contains(aReporter));
+
+  if (mWeakReporters->Contains(aReporter)) {
+    mWeakReporters->Remove(aReporter);
+    return NS_OK;
+  }
+
+  // We don't register new reporters when the block is in place, but we do
+  // unregister existing reporters. This is so we don't keep holding weak
+  // references that the old reporters aren't expecting (which can end up as
+  // dangling pointers that lead to use-after-frees).
+  if (mSavedWeakReporters && mSavedWeakReporters->Contains(aReporter)) {
+    mSavedWeakReporters->Remove(aReporter);
+    return NS_OK;
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::BlockRegistrationAndHideExistingReporters()
+{
+  // This method is thread-safe.
+  mozilla::MutexAutoLock autoLock(mMutex);
+  if (mIsRegistrationBlocked) {
+    return NS_ERROR_FAILURE;
+  }
+  mIsRegistrationBlocked = true;
+
+  // Hide the existing reporters, saving them for later restoration.
+  MOZ_ASSERT(!mSavedStrongReporters);
+  MOZ_ASSERT(!mSavedWeakReporters);
+  mSavedStrongReporters = mStrongReporters;
+  mSavedWeakReporters = mWeakReporters;
+  mStrongReporters = new StrongReportersTable();
+  mWeakReporters = new WeakReportersTable();
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::UnblockRegistrationAndRestoreOriginalReporters()
+{
+  // This method is thread-safe.
+  mozilla::MutexAutoLock autoLock(mMutex);
+  if (!mIsRegistrationBlocked) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Banish the current reporters, and restore the hidden ones.
+  delete mStrongReporters;
+  delete mWeakReporters;
+  mStrongReporters = mSavedStrongReporters;
+  mWeakReporters = mSavedWeakReporters;
+  mSavedStrongReporters = nullptr;
+  mSavedWeakReporters = nullptr;
+
+  mIsRegistrationBlocked = false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetVsize(int64_t* aVsize)
+{
+#ifdef HAVE_VSIZE_AND_RESIDENT_REPORTERS
+  return VsizeDistinguishedAmount(aVsize);
+#else
+  *aVsize = 0;
+  return NS_ERROR_NOT_AVAILABLE;
+#endif
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetVsizeMaxContiguous(int64_t* aAmount)
+{
+#ifdef HAVE_VSIZE_MAX_CONTIGUOUS_REPORTER
+  return VsizeMaxContiguousDistinguishedAmount(aAmount);
+#else
+  *aAmount = 0;
+  return NS_ERROR_NOT_AVAILABLE;
+#endif
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetResident(int64_t* aAmount)
+{
+#ifdef HAVE_VSIZE_AND_RESIDENT_REPORTERS
+  return ResidentDistinguishedAmount(aAmount);
+#else
+  *aAmount = 0;
+  return NS_ERROR_NOT_AVAILABLE;
+#endif
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetResidentFast(int64_t* aAmount)
+{
+#ifdef HAVE_VSIZE_AND_RESIDENT_REPORTERS
+  return ResidentFastDistinguishedAmount(aAmount);
+#else
+  *aAmount = 0;
+  return NS_ERROR_NOT_AVAILABLE;
+#endif
+}
+
+/*static*/ int64_t
+nsMemoryReporterManager::ResidentFast()
+{
+#ifdef HAVE_VSIZE_AND_RESIDENT_REPORTERS
+  int64_t amount;
+  nsresult rv = ResidentFastDistinguishedAmount(&amount);
+  NS_ENSURE_SUCCESS(rv, 0);
+  return amount;
+#else
+  return 0;
+#endif
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetResidentPeak(int64_t* aAmount)
+{
+#ifdef HAVE_RESIDENT_PEAK_REPORTER
+  return ResidentPeakDistinguishedAmount(aAmount);
+#else
+  *aAmount = 0;
+  return NS_ERROR_NOT_AVAILABLE;
+#endif
+}
+
+/*static*/ int64_t
+nsMemoryReporterManager::ResidentPeak()
+{
+#ifdef HAVE_RESIDENT_PEAK_REPORTER
+  int64_t amount = 0;
+  nsresult rv = ResidentPeakDistinguishedAmount(&amount);
+  NS_ENSURE_SUCCESS(rv, 0);
+  return amount;
+#else
+  return 0;
+#endif
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetResidentUnique(int64_t* aAmount)
+{
+#ifdef HAVE_RESIDENT_UNIQUE_REPORTER
+  return ResidentUniqueDistinguishedAmount(aAmount);
+#else
+  *aAmount = 0;
+  return NS_ERROR_NOT_AVAILABLE;
+#endif
+}
+
+/*static*/ int64_t
+nsMemoryReporterManager::ResidentUnique()
+{
+#ifdef HAVE_RESIDENT_UNIQUE_REPORTER
+  int64_t amount = 0;
+  nsresult rv = ResidentUniqueDistinguishedAmount(&amount);
+  NS_ENSURE_SUCCESS(rv, 0);
+  return amount;
+#else
+  return 0;
+#endif
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetHeapAllocated(int64_t* aAmount)
+{
+#ifdef HAVE_JEMALLOC_STATS
+  jemalloc_stats_t stats;
+  jemalloc_stats(&stats);
+  *aAmount = stats.allocated;
+  return NS_OK;
+#else
+  *aAmount = 0;
+  return NS_ERROR_NOT_AVAILABLE;
+#endif
+}
+
+// This has UNITS_PERCENTAGE, so it is multiplied by 100x.
+NS_IMETHODIMP
+nsMemoryReporterManager::GetHeapOverheadFraction(int64_t* aAmount)
+{
+#ifdef HAVE_JEMALLOC_STATS
+  jemalloc_stats_t stats;
+  jemalloc_stats(&stats);
+  *aAmount = HeapOverheadFraction(&stats);
+  return NS_OK;
+#else
+  *aAmount = 0;
+  return NS_ERROR_NOT_AVAILABLE;
+#endif
+}
+
+static MOZ_MUST_USE nsresult
+GetInfallibleAmount(InfallibleAmountFn aAmountFn, int64_t* aAmount)
+{
+  if (aAmountFn) {
+    *aAmount = aAmountFn();
+    return NS_OK;
+  }
+  *aAmount = 0;
+  return NS_ERROR_NOT_AVAILABLE;
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetJSMainRuntimeGCHeap(int64_t* aAmount)
+{
+  return GetInfallibleAmount(mAmountFns.mJSMainRuntimeGCHeap, aAmount);
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetJSMainRuntimeTemporaryPeak(int64_t* aAmount)
+{
+  return GetInfallibleAmount(mAmountFns.mJSMainRuntimeTemporaryPeak, aAmount);
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetJSMainRuntimeCompartmentsSystem(int64_t* aAmount)
+{
+  return GetInfallibleAmount(mAmountFns.mJSMainRuntimeCompartmentsSystem,
+                             aAmount);
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetJSMainRuntimeCompartmentsUser(int64_t* aAmount)
+{
+  return GetInfallibleAmount(mAmountFns.mJSMainRuntimeCompartmentsUser,
+                             aAmount);
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetImagesContentUsedUncompressed(int64_t* aAmount)
+{
+  return GetInfallibleAmount(mAmountFns.mImagesContentUsedUncompressed,
+                             aAmount);
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetStorageSQLite(int64_t* aAmount)
+{
+  return GetInfallibleAmount(mAmountFns.mStorageSQLite, aAmount);
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetLowMemoryEventsVirtual(int64_t* aAmount)
+{
+  return GetInfallibleAmount(mAmountFns.mLowMemoryEventsVirtual, aAmount);
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetLowMemoryEventsPhysical(int64_t* aAmount)
+{
+  return GetInfallibleAmount(mAmountFns.mLowMemoryEventsPhysical, aAmount);
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetGhostWindows(int64_t* aAmount)
+{
+  return GetInfallibleAmount(mAmountFns.mGhostWindows, aAmount);
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetPageFaultsHard(int64_t* aAmount)
+{
+#ifdef HAVE_PAGE_FAULT_REPORTERS
+  return PageFaultsHardDistinguishedAmount(aAmount);
+#else
+  *aAmount = 0;
+  return NS_ERROR_NOT_AVAILABLE;
+#endif
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetHasMozMallocUsableSize(bool* aHas)
+{
+  void* p = malloc(16);
+  if (!p) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  size_t usable = moz_malloc_usable_size(p);
+  free(p);
+  *aHas = !!(usable > 0);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetIsDMDEnabled(bool* aIsEnabled)
+{
+#ifdef MOZ_DMD
+  *aIsEnabled = true;
+#else
+  *aIsEnabled = false;
+#endif
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::GetIsDMDRunning(bool* aIsRunning)
+{
+#ifdef MOZ_DMD
+  *aIsRunning = dmd::IsRunning();
+#else
+  *aIsRunning = false;
+#endif
+  return NS_OK;
+}
+
+namespace {
+
+/**
+ * This runnable lets us implement
+ * nsIMemoryReporterManager::MinimizeMemoryUsage().  We fire a heap-minimize
+ * notification, spin the event loop, and repeat this process a few times.
+ *
+ * When this sequence finishes, we invoke the callback function passed to the
+ * runnable's constructor.
+ */
+class MinimizeMemoryUsageRunnable : public Runnable
+{
+public:
+  explicit MinimizeMemoryUsageRunnable(nsIRunnable* aCallback)
+    : mCallback(aCallback)
+    , mRemainingIters(sNumIters)
+  {
+  }
+
+  NS_IMETHOD Run() override
+  {
+    nsCOMPtr<nsIObserverService> os = services::GetObserverService();
+    if (!os) {
+      return NS_ERROR_FAILURE;
+    }
+
+    if (mRemainingIters == 0) {
+      os->NotifyObservers(nullptr, "after-minimize-memory-usage",
+                          u"MinimizeMemoryUsageRunnable");
+      if (mCallback) {
+        mCallback->Run();
+      }
+      return NS_OK;
+    }
+
+    os->NotifyObservers(nullptr, "memory-pressure", u"heap-minimize");
+    mRemainingIters--;
+    NS_DispatchToMainThread(this);
+
+    return NS_OK;
+  }
+
+private:
+  // Send sNumIters heap-minimize notifications, spinning the event
+  // loop after each notification (see bug 610166 comment 12 for an
+  // explanation), because one notification doesn't cut it.
+  static const uint32_t sNumIters = 3;
+
+  nsCOMPtr<nsIRunnable> mCallback;
+  uint32_t mRemainingIters;
+};
+
+} // namespace
+
+NS_IMETHODIMP
+nsMemoryReporterManager::MinimizeMemoryUsage(nsIRunnable* aCallback)
+{
+  RefPtr<MinimizeMemoryUsageRunnable> runnable =
+    new MinimizeMemoryUsageRunnable(aCallback);
+
+  return NS_DispatchToMainThread(runnable);
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::SizeOfTab(mozIDOMWindowProxy* aTopWindow,
+                                   int64_t* aJSObjectsSize,
+                                   int64_t* aJSStringsSize,
+                                   int64_t* aJSOtherSize,
+                                   int64_t* aDomSize,
+                                   int64_t* aStyleSize,
+                                   int64_t* aOtherSize,
+                                   int64_t* aTotalSize,
+                                   double*  aJSMilliseconds,
+                                   double*  aNonJSMilliseconds)
+{
+  nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(aTopWindow);
+  auto* piWindow = nsPIDOMWindowOuter::From(aTopWindow);
+  if (NS_WARN_IF(!global) || NS_WARN_IF(!piWindow)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  TimeStamp t1 = TimeStamp::Now();
+
+  // Measure JS memory consumption (and possibly some non-JS consumption, via
+  // |jsPrivateSize|).
+  size_t jsObjectsSize, jsStringsSize, jsPrivateSize, jsOtherSize;
+  nsresult rv = mSizeOfTabFns.mJS(global->GetGlobalJSObject(),
+                                  &jsObjectsSize, &jsStringsSize,
+                                  &jsPrivateSize, &jsOtherSize);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  TimeStamp t2 = TimeStamp::Now();
+
+  // Measure non-JS memory consumption.
+  size_t domSize, styleSize, otherSize;
+  rv = mSizeOfTabFns.mNonJS(piWindow, &domSize, &styleSize, &otherSize);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  TimeStamp t3 = TimeStamp::Now();
+
+  *aTotalSize = 0;
+#define DO(aN, n) { *aN = (n); *aTotalSize += (n); }
+  DO(aJSObjectsSize, jsObjectsSize);
+  DO(aJSStringsSize, jsStringsSize);
+  DO(aJSOtherSize,   jsOtherSize);
+  DO(aDomSize,       jsPrivateSize + domSize);
+  DO(aStyleSize,     styleSize);
+  DO(aOtherSize,     otherSize);
+#undef DO
+
+  *aJSMilliseconds    = (t2 - t1).ToMilliseconds();
+  *aNonJSMilliseconds = (t3 - t2).ToMilliseconds();
+
+  return NS_OK;
+}
+
+namespace mozilla {
+
+#define GET_MEMORY_REPORTER_MANAGER(mgr)                                      \
+  RefPtr<nsMemoryReporterManager> mgr =                                       \
+    nsMemoryReporterManager::GetOrCreate();                                   \
+  if (!mgr) {                                                                 \
+    return NS_ERROR_FAILURE;                                                  \
+  }
+
+nsresult
+RegisterStrongMemoryReporter(nsIMemoryReporter* aReporter)
+{
+  // Hold a strong reference to the argument to make sure it gets released if
+  // we return early below.
+  nsCOMPtr<nsIMemoryReporter> reporter = aReporter;
+  GET_MEMORY_REPORTER_MANAGER(mgr)
+  return mgr->RegisterStrongReporter(reporter);
+}
+
+nsresult
+RegisterStrongAsyncMemoryReporter(nsIMemoryReporter* aReporter)
+{
+  // Hold a strong reference to the argument to make sure it gets released if
+  // we return early below.
+  nsCOMPtr<nsIMemoryReporter> reporter = aReporter;
+  GET_MEMORY_REPORTER_MANAGER(mgr)
+  return mgr->RegisterStrongAsyncReporter(reporter);
+}
+
+nsresult
+RegisterWeakMemoryReporter(nsIMemoryReporter* aReporter)
+{
+  GET_MEMORY_REPORTER_MANAGER(mgr)
+  return mgr->RegisterWeakReporter(aReporter);
+}
+
+nsresult
+RegisterWeakAsyncMemoryReporter(nsIMemoryReporter* aReporter)
+{
+  GET_MEMORY_REPORTER_MANAGER(mgr)
+  return mgr->RegisterWeakAsyncReporter(aReporter);
+}
+
+nsresult
+UnregisterStrongMemoryReporter(nsIMemoryReporter* aReporter)
+{
+  GET_MEMORY_REPORTER_MANAGER(mgr)
+  return mgr->UnregisterStrongReporter(aReporter);
+}
+
+nsresult
+UnregisterWeakMemoryReporter(nsIMemoryReporter* aReporter)
+{
+  GET_MEMORY_REPORTER_MANAGER(mgr)
+  return mgr->UnregisterWeakReporter(aReporter);
+}
+
+// Macro for generating functions that register distinguished amount functions
+// with the memory reporter manager.
+#define DEFINE_REGISTER_DISTINGUISHED_AMOUNT(kind, name)                      \
+  nsresult                                                                    \
+  Register##name##DistinguishedAmount(kind##AmountFn aAmountFn)               \
+  {                                                                           \
+    GET_MEMORY_REPORTER_MANAGER(mgr)                                          \
+    mgr->mAmountFns.m##name = aAmountFn;                                      \
+    return NS_OK;                                                             \
+  }
+
+// Macro for generating functions that unregister distinguished amount
+// functions with the memory reporter manager.
+#define DEFINE_UNREGISTER_DISTINGUISHED_AMOUNT(name)                          \
+  nsresult                                                                    \
+  Unregister##name##DistinguishedAmount()                                     \
+  {                                                                           \
+    GET_MEMORY_REPORTER_MANAGER(mgr)                                          \
+    mgr->mAmountFns.m##name = nullptr;                                        \
+    return NS_OK;                                                             \
+  }
+
+DEFINE_REGISTER_DISTINGUISHED_AMOUNT(Infallible, JSMainRuntimeGCHeap)
+DEFINE_REGISTER_DISTINGUISHED_AMOUNT(Infallible, JSMainRuntimeTemporaryPeak)
+DEFINE_REGISTER_DISTINGUISHED_AMOUNT(Infallible, JSMainRuntimeCompartmentsSystem)
+DEFINE_REGISTER_DISTINGUISHED_AMOUNT(Infallible, JSMainRuntimeCompartmentsUser)
+
+DEFINE_REGISTER_DISTINGUISHED_AMOUNT(Infallible, ImagesContentUsedUncompressed)
+DEFINE_UNREGISTER_DISTINGUISHED_AMOUNT(ImagesContentUsedUncompressed)
+
+DEFINE_REGISTER_DISTINGUISHED_AMOUNT(Infallible, StorageSQLite)
+DEFINE_UNREGISTER_DISTINGUISHED_AMOUNT(StorageSQLite)
+
+DEFINE_REGISTER_DISTINGUISHED_AMOUNT(Infallible, LowMemoryEventsVirtual)
+DEFINE_REGISTER_DISTINGUISHED_AMOUNT(Infallible, LowMemoryEventsPhysical)
+
+DEFINE_REGISTER_DISTINGUISHED_AMOUNT(Infallible, GhostWindows)
+
+#undef DEFINE_REGISTER_DISTINGUISHED_AMOUNT
+#undef DEFINE_UNREGISTER_DISTINGUISHED_AMOUNT
+
+#define DEFINE_REGISTER_SIZE_OF_TAB(name)                                     \
+  nsresult                                                                    \
+  Register##name##SizeOfTab(name##SizeOfTabFn aSizeOfTabFn)                   \
+  {                                                                           \
+    GET_MEMORY_REPORTER_MANAGER(mgr)                                          \
+    mgr->mSizeOfTabFns.m##name = aSizeOfTabFn;                                \
+    return NS_OK;                                                             \
+  }
+
+DEFINE_REGISTER_SIZE_OF_TAB(JS);
+DEFINE_REGISTER_SIZE_OF_TAB(NonJS);
+
+#undef DEFINE_REGISTER_SIZE_OF_TAB
+
+#undef GET_MEMORY_REPORTER_MANAGER
+
+} // namespace mozilla
diff --git a/xpcom/base/nsMemoryReporterManager.h b/xpcom/base/nsMemoryReporterManager.h
new file mode 100644
index 000000000..8240cbe34
--- /dev/null
+++ b/xpcom/base/nsMemoryReporterManager.h
@@ -0,0 +1,288 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMemoryReporterManager_h__
+#define nsMemoryReporterManager_h__
+
+#include "mozilla/Mutex.h"
+#include "nsHashKeys.h"
+#include "nsIMemoryReporter.h"
+#include "nsITimer.h"
+#include "nsServiceManagerUtils.h"
+#include "nsTHashtable.h"
+
+namespace mozilla {
+namespace dom {
+class ContentParent;
+class MemoryReport;
+} // namespace dom
+} // namespace mozilla
+
+class nsITimer;
+
+class nsMemoryReporterManager final : public nsIMemoryReporterManager
+{
+  virtual ~nsMemoryReporterManager();
+
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIMEMORYREPORTERMANAGER
+
+  nsMemoryReporterManager();
+
+  // Gets the memory reporter manager service.
+  static nsMemoryReporterManager* GetOrCreate()
+  {
+    nsCOMPtr<nsIMemoryReporterManager> imgr =
+      do_GetService("@mozilla.org/memory-reporter-manager;1");
+    return static_cast<nsMemoryReporterManager*>(imgr.get());
+  }
+
+  typedef nsDataHashtable<nsRefPtrHashKey<nsIMemoryReporter>, bool> StrongReportersTable;
+  typedef nsDataHashtable<nsPtrHashKey<nsIMemoryReporter>, bool> WeakReportersTable;
+
+  // Inter-process memory reporting proceeds as follows.
+  //
+  // - GetReports() (declared within NS_DECL_NSIMEMORYREPORTERMANAGER)
+  //   synchronously gets memory reports for the current process, sets up some
+  //   state (mPendingProcessesState) for when child processes report back --
+  //   including a timer -- and starts telling child processes to get memory
+  //   reports.  Control then returns to the main event loop.
+  //
+  //   The number of concurrent child process reports is limited by the pref
+  //   "memory.report_concurrency" in order to prevent the memory overhead of
+  //   memory reporting from causing problems, especially on B2G when swapping
+  //   to compressed RAM; see bug 1154053.
+  //
+  // - HandleChildReport() is called (asynchronously) once per child process
+  //   reporter callback.
+  //
+  // - EndProcessReport() is called (asynchronously) once per process that
+  //   finishes reporting back, including the parent.  If all processes do so
+  //   before time-out, the timer is cancelled.  If there are child processes
+  //   whose requests have not yet been sent, they will be started until the
+  //   concurrency limit is (again) reached.
+  //
+  // - TimeoutCallback() is called (asynchronously) if all the child processes
+  //   don't respond within the time threshold.
+  //
+  // - FinishReporting() finishes things off.  It is *always* called -- either
+  //   from EndChildReport() (if all child processes have reported back) or
+  //   from TimeoutCallback() (if time-out occurs).
+  //
+  // All operations occur on the main thread.
+  //
+  // The above sequence of steps is a "request".  A partially-completed request
+  // is described as "in flight".
+  //
+  // Each request has a "generation", a unique number that identifies it.  This
+  // is used to ensure that each reports from a child process corresponds to
+  // the appropriate request from the parent process.  (It's easier to
+  // implement a generation system than to implement a child report request
+  // cancellation mechanism.)
+  //
+  // Failures are mostly ignored, because it's (a) typically the most sensible
+  // thing to do, and (b) often hard to do anything else.  The following are
+  // the failure cases of note.
+  //
+  // - If a request is made while the previous request is in flight, the new
+  //   request is ignored, as per getReports()'s specification.  No error is
+  //   reported, because the previous request will complete soon enough.
+  //
+  // - If one or more child processes fail to respond within the time limit,
+  //   things will proceed as if they don't exist.  No error is reported,
+  //   because partial information is better than nothing.
+  //
+  // - If a child process reports after the time-out occurs, it is ignored.
+  //   (Generation checking will ensure it is ignored even if a subsequent
+  //   request is in flight;  this is the main use of generations.)  No error
+  //   is reported, because there's nothing sensible to be done about it at
+  //   this late stage.
+  //
+  // - If the time-out occurs after a child process has sent some reports but
+  //   before it has signaled completion (see bug 1151597), then what it
+  //   successfully sent will be included, with no explicit indication that it
+  //   is incomplete.
+  //
+  // Now, what what happens if a child process is created/destroyed in the
+  // middle of a request?  Well, PendingProcessesState is initialized with an array
+  // of child process actors as of when the report started.  So...
+  //
+  // - If a process is created after reporting starts, it won't be sent a
+  //   request for reports.  So the reported data will reflect how things were
+  //   when the request began.
+  //
+  // - If a process is destroyed before it starts reporting back, the reported
+  //   data will reflect how things are when the request ends.
+  //
+  // - If a process is destroyed after it starts reporting back but before it
+  //   finishes, the reported data will contain a partial report for it.
+  //
+  // - If a process is destroyed after reporting back, but before all other
+  //   child processes have reported back, it will be included in the reported
+  //   data.  So the reported data will reflect how things were when the
+  //   request began.
+  //
+  // The inconsistencies between these cases are unfortunate but difficult to
+  // avoid.  It's enough of an edge case to not be worth doing more.
+  //
+  void HandleChildReport(uint32_t aGeneration,
+                         const mozilla::dom::MemoryReport& aChildReport);
+  void EndProcessReport(uint32_t aGeneration, bool aSuccess);
+
+  // Functions that (a) implement distinguished amounts, and (b) are outside of
+  // this module.
+  struct AmountFns
+  {
+    mozilla::InfallibleAmountFn mJSMainRuntimeGCHeap;
+    mozilla::InfallibleAmountFn mJSMainRuntimeTemporaryPeak;
+    mozilla::InfallibleAmountFn mJSMainRuntimeCompartmentsSystem;
+    mozilla::InfallibleAmountFn mJSMainRuntimeCompartmentsUser;
+
+    mozilla::InfallibleAmountFn mImagesContentUsedUncompressed;
+
+    mozilla::InfallibleAmountFn mStorageSQLite;
+
+    mozilla::InfallibleAmountFn mLowMemoryEventsVirtual;
+    mozilla::InfallibleAmountFn mLowMemoryEventsPhysical;
+
+    mozilla::InfallibleAmountFn mGhostWindows;
+
+    AmountFns()
+    {
+      mozilla::PodZero(this);
+    }
+  };
+  AmountFns mAmountFns;
+
+  // Convenience function to get RSS easily from other code.  This is useful
+  // when debugging transient memory spikes with printf instrumentation.
+  static int64_t ResidentFast();
+
+  // Convenience function to get peak RSS easily from other code.
+  static int64_t ResidentPeak();
+
+  // Convenience function to get USS easily from other code.  This is useful
+  // when debugging unshared memory pages for forked processes.
+  static int64_t ResidentUnique();
+
+  // Functions that measure per-tab memory consumption.
+  struct SizeOfTabFns
+  {
+    mozilla::JSSizeOfTabFn    mJS;
+    mozilla::NonJSSizeOfTabFn mNonJS;
+
+    SizeOfTabFns()
+    {
+      mozilla::PodZero(this);
+    }
+  };
+  SizeOfTabFns mSizeOfTabFns;
+
+private:
+  MOZ_MUST_USE nsresult
+  RegisterReporterHelper(nsIMemoryReporter* aReporter,
+                         bool aForce, bool aStrongRef, bool aIsAsync);
+
+  MOZ_MUST_USE nsresult StartGettingReports();
+  // No MOZ_MUST_USE here because ignoring the result is common and reasonable.
+  nsresult FinishReporting();
+
+  void DispatchReporter(nsIMemoryReporter* aReporter, bool aIsAsync,
+                        nsIHandleReportCallback* aHandleReport,
+                        nsISupports* aHandleReportData,
+                        bool aAnonymize);
+
+  static void TimeoutCallback(nsITimer* aTimer, void* aData);
+  // Note: this timeout needs to be long enough to allow for the
+  // possibility of DMD reports and/or running on a low-end phone.
+  static const uint32_t kTimeoutLengthMS = 50000;
+
+  mozilla::Mutex mMutex;
+  bool mIsRegistrationBlocked;
+
+  StrongReportersTable* mStrongReporters;
+  WeakReportersTable* mWeakReporters;
+
+  // These two are only used for testing purposes.
+  StrongReportersTable* mSavedStrongReporters;
+  WeakReportersTable* mSavedWeakReporters;
+
+  uint32_t mNextGeneration;
+
+  // Used to keep track of state of which processes are currently running and
+  // waiting to run memory reports. Holds references to parameters needed when
+  // requesting a memory report and finishing reporting.
+  struct PendingProcessesState
+  {
+    uint32_t                             mGeneration;
+    bool                                 mAnonymize;
+    bool                                 mMinimize;
+    nsCOMPtr<nsITimer>                   mTimer;
+    nsTArray<RefPtr<mozilla::dom::ContentParent>> mChildrenPending;
+    uint32_t                             mNumProcessesRunning;
+    uint32_t                             mNumProcessesCompleted;
+    uint32_t                             mConcurrencyLimit;
+    nsCOMPtr<nsIHandleReportCallback>    mHandleReport;
+    nsCOMPtr<nsISupports>                mHandleReportData;
+    nsCOMPtr<nsIFinishReportingCallback> mFinishReporting;
+    nsCOMPtr<nsISupports>                mFinishReportingData;
+    nsString                             mDMDDumpIdent;
+
+    PendingProcessesState(uint32_t aGeneration, bool aAnonymize, bool aMinimize,
+                          uint32_t aConcurrencyLimit,
+                          nsIHandleReportCallback* aHandleReport,
+                          nsISupports* aHandleReportData,
+                          nsIFinishReportingCallback* aFinishReporting,
+                          nsISupports* aFinishReportingData,
+                          const nsAString& aDMDDumpIdent);
+  };
+
+  // Used to keep track of the state of the asynchronously run memory
+  // reporters. The callback and file handle used when all memory reporters
+  // have finished are also stored here.
+  struct PendingReportersState
+  {
+    // Number of memory reporters currently running.
+    uint32_t mReportsPending;
+
+    // Callback for when all memory reporters have completed.
+    nsCOMPtr<nsIFinishReportingCallback> mFinishReporting;
+    nsCOMPtr<nsISupports> mFinishReportingData;
+
+    // File handle to write a DMD report to if requested.
+    FILE* mDMDFile;
+
+    PendingReportersState(nsIFinishReportingCallback* aFinishReporting,
+                        nsISupports* aFinishReportingData,
+                        FILE* aDMDFile)
+      : mReportsPending(0)
+      , mFinishReporting(aFinishReporting)
+      , mFinishReportingData(aFinishReportingData)
+      , mDMDFile(aDMDFile)
+    {
+    }
+  };
+
+  // When this is non-null, a request is in flight.  Note: We use manual
+  // new/delete for this because its lifetime doesn't match block scope or
+  // anything like that.
+  PendingProcessesState* mPendingProcessesState;
+
+  // This is reinitialized each time a call to GetReports is initiated.
+  PendingReportersState* mPendingReportersState;
+
+  PendingProcessesState* GetStateForGeneration(uint32_t aGeneration);
+  static MOZ_MUST_USE bool
+  StartChildReport(mozilla::dom::ContentParent* aChild,
+                   const PendingProcessesState* aState);
+};
+
+#define NS_MEMORY_REPORTER_MANAGER_CID \
+{ 0xfb97e4f5, 0x32dd, 0x497a, \
+{ 0xba, 0xa2, 0x7d, 0x1e, 0x55, 0x7, 0x99, 0x10 } }
+
+#endif // nsMemoryReporterManager_h__
diff --git a/xpcom/base/nsMessageLoop.cpp b/xpcom/base/nsMessageLoop.cpp
new file mode 100644
index 000000000..fabf6b9f5
--- /dev/null
+++ b/xpcom/base/nsMessageLoop.cpp
@@ -0,0 +1,172 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsMessageLoop.h"
+#include "mozilla/WeakPtr.h"
+#include "base/message_loop.h"
+#include "base/task.h"
+#include "nsIRunnable.h"
+#include "nsITimer.h"
+#include "nsCOMPtr.h"
+#include "nsAutoPtr.h"
+#include "nsComponentManagerUtils.h"
+#include "nsThreadUtils.h"
+
+using namespace mozilla;
+
+namespace {
+
+/**
+ * This Task runs its nsIRunnable when Run() is called, or after
+ * aEnsureRunsAfterMS milliseconds have elapsed since the object was
+ * constructed.
+ *
+ * Note that the MessageLoop owns this object and will delete it after it calls
+ * Run().  Tread lightly.
+ */
+class MessageLoopIdleTask
+  : public Runnable
+  , public SupportsWeakPtr<MessageLoopIdleTask>
+{
+public:
+  MOZ_DECLARE_WEAKREFERENCE_TYPENAME(MessageLoopIdleTask)
+  MessageLoopIdleTask(nsIRunnable* aTask, uint32_t aEnsureRunsAfterMS);
+  NS_IMETHOD Run() override;
+
+private:
+  nsresult Init(uint32_t aEnsureRunsAfterMS);
+
+  nsCOMPtr<nsIRunnable> mTask;
+  nsCOMPtr<nsITimer> mTimer;
+
+  virtual ~MessageLoopIdleTask() {}
+};
+
+/**
+ * This timer callback calls MessageLoopIdleTask::Run() when its timer fires.
+ * (The timer can't call back into MessageLoopIdleTask directly since that's
+ * not a refcounted object; it's owned by the MessageLoop.)
+ *
+ * We keep a weak reference to the MessageLoopIdleTask, although a raw pointer
+ * should in theory suffice: When the MessageLoopIdleTask runs (right before
+ * the MessageLoop deletes it), it cancels its timer.  But the weak pointer
+ * saves us from worrying about an edge case somehow messing us up here.
+ */
+class MessageLoopTimerCallback
+  : public nsITimerCallback
+{
+public:
+  explicit MessageLoopTimerCallback(MessageLoopIdleTask* aTask);
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSITIMERCALLBACK
+
+private:
+  WeakPtr<MessageLoopIdleTask> mTask;
+
+  virtual ~MessageLoopTimerCallback() {}
+};
+
+MessageLoopIdleTask::MessageLoopIdleTask(nsIRunnable* aTask,
+                                         uint32_t aEnsureRunsAfterMS)
+  : mTask(aTask)
+{
+  // Init() really shouldn't fail, but if it does, we schedule our runnable
+  // immediately, because it's more important to guarantee that we run the task
+  // eventually than it is to run the task when we're idle.
+  nsresult rv = Init(aEnsureRunsAfterMS);
+  if (NS_FAILED(rv)) {
+    NS_WARNING("Running idle task early because we couldn't initialize our timer.");
+    NS_DispatchToCurrentThread(mTask);
+
+    mTask = nullptr;
+    mTimer = nullptr;
+  }
+}
+
+nsresult
+MessageLoopIdleTask::Init(uint32_t aEnsureRunsAfterMS)
+{
+  mTimer = do_CreateInstance("@mozilla.org/timer;1");
+  if (NS_WARN_IF(!mTimer)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  RefPtr<MessageLoopTimerCallback> callback =
+    new MessageLoopTimerCallback(this);
+
+  return mTimer->InitWithCallback(callback, aEnsureRunsAfterMS,
+                                  nsITimer::TYPE_ONE_SHOT);
+}
+
+NS_IMETHODIMP
+MessageLoopIdleTask::Run()
+{
+  // Null out our pointers because if Run() was called by the timer, this
+  // object will be kept alive by the MessageLoop until the MessageLoop calls
+  // Run().
+
+  if (mTimer) {
+    mTimer->Cancel();
+    mTimer = nullptr;
+  }
+
+  if (mTask) {
+    mTask->Run();
+    mTask = nullptr;
+  }
+
+  return NS_OK;
+}
+
+MessageLoopTimerCallback::MessageLoopTimerCallback(MessageLoopIdleTask* aTask)
+  : mTask(aTask)
+{
+}
+
+NS_IMETHODIMP
+MessageLoopTimerCallback::Notify(nsITimer* aTimer)
+{
+  // We don't expect to hit the case when the timer fires but mTask has been
+  // deleted, because mTask should cancel the timer before the mTask is
+  // deleted.  But you never know...
+  NS_WARNING_ASSERTION(mTask, "This timer shouldn't have fired.");
+
+  if (mTask) {
+    mTask->Run();
+  }
+  return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS(MessageLoopTimerCallback, nsITimerCallback)
+
+} // namespace
+
+NS_IMPL_ISUPPORTS(nsMessageLoop, nsIMessageLoop)
+
+NS_IMETHODIMP
+nsMessageLoop::PostIdleTask(nsIRunnable* aTask, uint32_t aEnsureRunsAfterMS)
+{
+  // The message loop owns MessageLoopIdleTask and deletes it after calling
+  // Run().  Be careful...
+  RefPtr<MessageLoopIdleTask> idle =
+    new MessageLoopIdleTask(aTask, aEnsureRunsAfterMS);
+  MessageLoop::current()->PostIdleTask(idle.forget());
+
+  return NS_OK;
+}
+
+nsresult
+nsMessageLoopConstructor(nsISupports* aOuter,
+                         const nsIID& aIID,
+                         void** aInstancePtr)
+{
+  if (NS_WARN_IF(aOuter)) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+  nsISupports* messageLoop = new nsMessageLoop();
+  return messageLoop->QueryInterface(aIID, aInstancePtr);
+}
diff --git a/xpcom/base/nsMessageLoop.h b/xpcom/base/nsMessageLoop.h
new file mode 100644
index 000000000..e7b146221
--- /dev/null
+++ b/xpcom/base/nsMessageLoop.h
@@ -0,0 +1,31 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIMessageLoop.h"
+
+/*
+ * nsMessageLoop implements nsIMessageLoop, which wraps Chromium's MessageLoop
+ * class and adds a bit of sugar.
+ */
+class nsMessageLoop : public nsIMessageLoop
+{
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIMESSAGELOOP
+
+private:
+  virtual ~nsMessageLoop()
+  {
+  }
+};
+
+#define NS_MESSAGE_LOOP_CID \
+{0x67b3ac0c, 0xd806, 0x4d48, \
+{0x93, 0x9e, 0x6a, 0x81, 0x9e, 0x6c, 0x24, 0x8f}}
+
+extern nsresult
+nsMessageLoopConstructor(nsISupports* aOuter,
+                         const nsIID& aIID,
+                         void** aInstancePtr);
diff --git a/xpcom/base/nsObjCExceptions.h b/xpcom/base/nsObjCExceptions.h
new file mode 100644
index 000000000..e63c92af5
--- /dev/null
+++ b/xpcom/base/nsObjCExceptions.h
@@ -0,0 +1,230 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Undo the damage that exception_defines.h does.
+#undef try
+#undef catch
+
+#ifndef nsObjCExceptions_h_
+#define nsObjCExceptions_h_
+
+#import <Foundation/Foundation.h>
+
+#ifdef DEBUG
+#import <ExceptionHandling/NSExceptionHandler.h>
+#endif
+
+#if defined(MOZ_CRASHREPORTER) && defined(__cplusplus)
+#include "nsICrashReporter.h"
+#include "nsCOMPtr.h"
+#include "nsServiceManagerUtils.h"
+#endif
+
+#include <unistd.h>
+#include <signal.h>
+#include "nsError.h"
+
+// Undo the damage that exception_defines.h does.
+#undef try
+#undef catch
+
+/* NOTE: Macros that claim to abort no longer abort, see bug 486574.
+ * If you actually want to log and abort, call "nsObjCExceptionLogAbort"
+ * from an exception handler. At some point we will fix this by replacing
+ * all macros in the tree with appropriately-named macros.
+ */
+
+// See Mozilla bug 163260.
+// This file can only be included in an Objective-C context.
+
+__attribute__((unused))
+static void
+nsObjCExceptionLog(NSException* aException)
+{
+  NSLog(@"Mozilla has caught an Obj-C exception [%@: %@]",
+        [aException name], [aException reason]);
+
+#if defined(MOZ_CRASHREPORTER) && defined(__cplusplus)
+  // Attach exception info to the crash report.
+  nsCOMPtr<nsICrashReporter> crashReporter =
+    do_GetService("@mozilla.org/toolkit/crash-reporter;1");
+  if (crashReporter) {
+    crashReporter->AppendObjCExceptionInfoToAppNotes(static_cast<void*>(aException));
+  }
+#endif
+
+#ifdef DEBUG
+  @try {
+    // Try to get stack information out of the exception. 10.5 returns the stack
+    // info with the callStackReturnAddresses selector.
+    NSArray* stackTrace = nil;
+    if ([aException respondsToSelector:@selector(callStackReturnAddresses)]) {
+      NSArray* addresses = (NSArray*)
+        [aException performSelector:@selector(callStackReturnAddresses)];
+      if ([addresses count]) {
+        stackTrace = addresses;
+      }
+    }
+
+    // 10.4 doesn't respond to callStackReturnAddresses so we'll try to pull the
+    // stack info out of the userInfo. It might not be there, sadly :(
+    if (!stackTrace) {
+      stackTrace = [[aException userInfo] objectForKey:NSStackTraceKey];
+    }
+
+    if (stackTrace) {
+      // The command line should look like this:
+      //   /usr/bin/atos -p <pid> -printHeader <stack frame addresses>
+      NSMutableArray* args =
+        [NSMutableArray arrayWithCapacity:[stackTrace count] + 3];
+
+      [args addObject:@"-p"];
+      int pid = [[NSProcessInfo processInfo] processIdentifier];
+      [args addObject:[NSString stringWithFormat:@"%d", pid]];
+
+      [args addObject:@"-printHeader"];
+
+      unsigned int stackCount = [stackTrace count];
+      unsigned int stackIndex = 0;
+      for (; stackIndex < stackCount; stackIndex++) {
+        unsigned long address =
+          [[stackTrace objectAtIndex:stackIndex] unsignedLongValue];
+        [args addObject:[NSString stringWithFormat:@"0x%lx", address]];
+      }
+
+      NSPipe* outPipe = [NSPipe pipe];
+
+      NSTask* task = [[NSTask alloc] init];
+      [task setLaunchPath:@"/usr/bin/atos"];
+      [task setArguments:args];
+      [task setStandardOutput:outPipe];
+      [task setStandardError:outPipe];
+
+      NSLog(@"Generating stack trace for Obj-C exception...");
+
+      // This will throw an exception if the atos tool cannot be found, and in
+      // that case we'll just hit our @catch block below.
+      [task launch];
+
+      [task waitUntilExit];
+      [task release];
+
+      NSData* outData =
+        [[outPipe fileHandleForReading] readDataToEndOfFile];
+      NSString* outString =
+        [[NSString alloc] initWithData:outData encoding:NSUTF8StringEncoding];
+
+      NSLog(@"Stack trace:\n%@", outString);
+
+      [outString release];
+    } else {
+      NSLog(@"<No stack information available for Obj-C exception>");
+    }
+  }
+  @catch (NSException* exn) {
+    NSLog(@"Failed to generate stack trace for Obj-C exception [%@: %@]",
+          [exn name], [exn reason]);
+  }
+#endif
+}
+
+__attribute__((unused))
+static void
+nsObjCExceptionAbort()
+{
+  // We need to raise a mach-o signal here, the Mozilla crash reporter on
+  // Mac OS X does not respond to POSIX signals. Raising mach-o signals directly
+  // is tricky so we do it by just derefing a null pointer.
+  int* foo = nullptr;
+  *foo = 1;
+}
+
+__attribute__((unused))
+static void
+nsObjCExceptionLogAbort(NSException* aException)
+{
+  nsObjCExceptionLog(aException);
+  nsObjCExceptionAbort();
+}
+
+#define NS_OBJC_TRY(_e, _fail)                     \
+@try { _e; }                                       \
+@catch(NSException *_exn) {                        \
+  nsObjCExceptionLog(_exn);                        \
+  _fail;                                           \
+}
+
+#define NS_OBJC_TRY_EXPR(_e, _fail)                \
+({                                                 \
+   typeof(_e) _tmp;                                \
+   @try { _tmp = (_e); }                           \
+   @catch(NSException *_exn) {                     \
+     nsObjCExceptionLog(_exn);                     \
+     _fail;                                        \
+   }                                               \
+   _tmp;                                           \
+})
+
+#define NS_OBJC_TRY_EXPR_NULL(_e)                  \
+NS_OBJC_TRY_EXPR(_e, 0)
+
+#define NS_OBJC_TRY_IGNORE(_e)                     \
+NS_OBJC_TRY(_e, )
+
+// To reduce code size the abort versions do not reuse above macros. This allows
+// catch blocks to only contain one call.
+
+#define NS_OBJC_TRY_ABORT(_e)                      \
+@try { _e; }                                       \
+@catch(NSException *_exn) {                        \
+  nsObjCExceptionLog(_exn);                        \
+}
+
+#define NS_OBJC_TRY_EXPR_ABORT(_e)                 \
+({                                                 \
+   typeof(_e) _tmp;                                \
+   @try { _tmp = (_e); }                           \
+   @catch(NSException *_exn) {                     \
+     nsObjCExceptionLog(_exn);                     \
+   }                                               \
+   _tmp;                                           \
+})
+
+// For wrapping blocks of Obj-C calls. Does not actually terminate.
+#define NS_OBJC_BEGIN_TRY_ABORT_BLOCK @try {
+#define NS_OBJC_END_TRY_ABORT_BLOCK   } @catch(NSException *_exn) {             \
+                                        nsObjCExceptionLog(_exn);               \
+                                      }
+
+// Same as above ABORT_BLOCK but returns a value after the try/catch block to
+// suppress compiler warnings. This allows us to avoid having to refactor code
+// to get scoping right when wrapping an entire method.
+
+#define NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NIL @try {
+#define NS_OBJC_END_TRY_ABORT_BLOCK_NIL   } @catch(NSException *_exn) {         \
+                                            nsObjCExceptionLog(_exn);           \
+                                          }                                     \
+                                          return nil;
+
+#define NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSNULL @try {
+#define NS_OBJC_END_TRY_ABORT_BLOCK_NSNULL   } @catch(NSException *_exn) {      \
+                                               nsObjCExceptionLog(_exn);        \
+                                             }                                  \
+                                             return nullptr;
+
+#define NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT @try {
+#define NS_OBJC_END_TRY_ABORT_BLOCK_NSRESULT   } @catch(NSException *_exn) {    \
+                                                 nsObjCExceptionLog(_exn);      \
+                                               }                                \
+                                               return NS_ERROR_FAILURE;
+
+#define NS_OBJC_BEGIN_TRY_ABORT_BLOCK_RETURN    @try {
+#define NS_OBJC_END_TRY_ABORT_BLOCK_RETURN(_rv) } @catch(NSException *_exn) {   \
+                                                  nsObjCExceptionLog(_exn);\
+                                                }                               \
+                                                return _rv;
+
+#endif // nsObjCExceptions_h_
diff --git a/xpcom/base/nsQueryObject.h b/xpcom/base/nsQueryObject.h
new file mode 100644
index 000000000..a52546324
--- /dev/null
+++ b/xpcom/base/nsQueryObject.h
@@ -0,0 +1,109 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsQueryObject_h
+#define nsQueryObject_h
+
+#include "mozilla/Attributes.h"
+
+#include "nsCOMPtr.h"
+#include "mozilla/RefPtr.h"
+
+/*****************************************************************************/
+
+template<class T>
+class MOZ_STACK_CLASS nsQueryObject final : public nsCOMPtr_helper
+{
+public:
+  explicit nsQueryObject(T* aRawPtr)
+    : mRawPtr(aRawPtr)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID& aIID,
+                                          void** aResult) const
+  {
+    nsresult status = mRawPtr ? mRawPtr->QueryInterface(aIID, aResult)
+                              : NS_ERROR_NULL_POINTER;
+    return status;
+  }
+private:
+  T* MOZ_NON_OWNING_REF mRawPtr;
+};
+
+template<class T>
+class MOZ_STACK_CLASS nsQueryObjectWithError final : public nsCOMPtr_helper
+{
+public:
+  nsQueryObjectWithError(T* aRawPtr, nsresult* aErrorPtr)
+    : mRawPtr(aRawPtr), mErrorPtr(aErrorPtr)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID& aIID,
+                                          void** aResult) const
+  {
+    nsresult status = mRawPtr ? mRawPtr->QueryInterface(aIID, aResult)
+                              : NS_ERROR_NULL_POINTER;
+    if (mErrorPtr) {
+      *mErrorPtr = status;
+    }
+    return status;
+  }
+private:
+  T* MOZ_NON_OWNING_REF mRawPtr;
+  nsresult* mErrorPtr;
+};
+
+/*****************************************************************************/
+
+/*****************************************************************************/
+
+template<class T>
+inline nsQueryObject<T>
+do_QueryObject(T* aRawPtr)
+{
+  return nsQueryObject<T>(aRawPtr);
+}
+
+template<class T>
+inline nsQueryObject<T>
+do_QueryObject(nsCOMPtr<T>& aRawPtr)
+{
+  return nsQueryObject<T>(aRawPtr);
+}
+
+template<class T>
+inline nsQueryObject<T>
+do_QueryObject(RefPtr<T>& aRawPtr)
+{
+  return nsQueryObject<T>(aRawPtr);
+}
+
+template<class T>
+inline nsQueryObjectWithError<T>
+do_QueryObject(T* aRawPtr, nsresult* aErrorPtr)
+{
+  return nsQueryObjectWithError<T>(aRawPtr, aErrorPtr);
+}
+
+template<class T>
+inline nsQueryObjectWithError<T>
+do_QueryObject(nsCOMPtr<T>& aRawPtr, nsresult* aErrorPtr)
+{
+  return nsQueryObjectWithError<T>(aRawPtr, aErrorPtr);
+}
+
+template<class T>
+inline nsQueryObjectWithError<T>
+do_QueryObject(RefPtr<T>& aRawPtr, nsresult* aErrorPtr)
+{
+  return nsQueryObjectWithError<T>(aRawPtr, aErrorPtr);
+}
+
+/*****************************************************************************/
+
+#endif // !defined(nsQueryObject_h)
diff --git a/xpcom/base/nsSecurityConsoleMessage.cpp b/xpcom/base/nsSecurityConsoleMessage.cpp
new file mode 100644
index 000000000..3e6409cf3
--- /dev/null
+++ b/xpcom/base/nsSecurityConsoleMessage.cpp
@@ -0,0 +1,45 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsSecurityConsoleMessage.h"
+
+NS_IMPL_ISUPPORTS(nsSecurityConsoleMessage, nsISecurityConsoleMessage)
+
+nsSecurityConsoleMessage::nsSecurityConsoleMessage()
+{
+}
+
+nsSecurityConsoleMessage::~nsSecurityConsoleMessage()
+{
+}
+
+NS_IMETHODIMP
+nsSecurityConsoleMessage::GetTag(nsAString& aTag)
+{
+  aTag = mTag;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSecurityConsoleMessage::SetTag(const nsAString& aTag)
+{
+  mTag = aTag;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSecurityConsoleMessage::GetCategory(nsAString& aCategory)
+{
+  aCategory = mCategory;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSecurityConsoleMessage::SetCategory(const nsAString& aCategory)
+{
+  mCategory = aCategory;
+  return NS_OK;
+}
diff --git a/xpcom/base/nsSecurityConsoleMessage.h b/xpcom/base/nsSecurityConsoleMessage.h
new file mode 100644
index 000000000..c93c13613
--- /dev/null
+++ b/xpcom/base/nsSecurityConsoleMessage.h
@@ -0,0 +1,30 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSecurityConsoleMessage_h__
+#define nsSecurityConsoleMessage_h__
+#include "nsISecurityConsoleMessage.h"
+#include "nsString.h"
+
+class nsSecurityConsoleMessage final : public nsISecurityConsoleMessage
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISECURITYCONSOLEMESSAGE
+
+  nsSecurityConsoleMessage();
+
+private:
+  ~nsSecurityConsoleMessage();
+
+protected:
+  nsString mTag;
+  nsString mCategory;
+};
+
+#define NS_SECURITY_CONSOLE_MESSAGE_CID \
+  {0x43ebf210, 0x8a7b, 0x4ddb, {0xa8, 0x3d, 0xb8, 0x7c, 0x51, 0xa0, 0x58, 0xdb}}
+#endif //nsSecurityConsoleMessage_h__
diff --git a/xpcom/base/nsSetDllDirectory.h b/xpcom/base/nsSetDllDirectory.h
new file mode 100644
index 000000000..0920d5936
--- /dev/null
+++ b/xpcom/base/nsSetDllDirectory.h
@@ -0,0 +1,45 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSetDllDirectory_h
+#define nsSetDllDirectory_h
+
+#ifndef XP_WIN
+#error This file only makes sense on Windows.
+#endif
+
+#include <windows.h>
+#include <nscore.h>
+#include <stdlib.h>
+
+namespace mozilla {
+
+static void
+SanitizeEnvironmentVariables()
+{
+  DWORD bufferSize = GetEnvironmentVariableW(L"PATH", nullptr, 0);
+  if (bufferSize) {
+    wchar_t* originalPath = new wchar_t[bufferSize];
+    if (bufferSize - 1 == GetEnvironmentVariableW(L"PATH", originalPath,
+                                                  bufferSize)) {
+      bufferSize = ExpandEnvironmentStringsW(originalPath, nullptr, 0);
+      if (bufferSize) {
+        wchar_t* newPath = new wchar_t[bufferSize];
+        if (ExpandEnvironmentStringsW(originalPath,
+                                      newPath,
+                                      bufferSize)) {
+          SetEnvironmentVariableW(L"PATH", newPath);
+        }
+        delete[] newPath;
+      }
+    }
+    delete[] originalPath;
+  }
+}
+
+}
+
+#endif
diff --git a/xpcom/base/nsStatusReporterManager.cpp b/xpcom/base/nsStatusReporterManager.cpp
new file mode 100644
index 000000000..491e7d458
--- /dev/null
+++ b/xpcom/base/nsStatusReporterManager.cpp
@@ -0,0 +1,320 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsStatusReporterManager.h"
+#include "nsCOMPtr.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsArrayEnumerator.h"
+#include "nsISimpleEnumerator.h"
+#include "nsIFile.h"
+#include "nsDumpUtils.h"
+#include "nsIFileStreams.h"
+#include "nsPrintfCString.h"
+
+#ifdef XP_WIN
+#include <process.h>
+#define getpid _getpid
+#else
+#include <unistd.h>
+#endif
+
+#ifdef XP_UNIX
+#define DO_STATUS_REPORT 1
+#endif
+
+#ifdef DO_STATUS_REPORT // {
+namespace {
+
+class DumpStatusInfoToTempDirRunnable : public mozilla::Runnable
+{
+public:
+  DumpStatusInfoToTempDirRunnable()
+  {
+  }
+
+  NS_IMETHOD Run() override
+  {
+    nsCOMPtr<nsIStatusReporterManager> mgr =
+      do_GetService("@mozilla.org/status-reporter-manager;1");
+    mgr->DumpReports();
+    return NS_OK;
+  }
+};
+
+void
+doStatusReport(const nsCString& aInputStr)
+{
+  LOG("FifoWatcher(%s) dispatching status report runnable.", aInputStr.get());
+  RefPtr<DumpStatusInfoToTempDirRunnable> runnable =
+    new DumpStatusInfoToTempDirRunnable();
+  NS_DispatchToMainThread(runnable);
+}
+
+} //anonymous namespace
+#endif // DO_STATUS_REPORT }
+
+static bool gStatusReportProgress = 0;
+static int gNumReporters = 0;
+
+nsresult
+getStatus(nsACString& aDesc)
+{
+  if (!gStatusReportProgress) {
+    aDesc.AssignLiteral("Init");
+  } else {
+    aDesc.AssignLiteral("Running: There are ");
+    aDesc.AppendInt(gNumReporters);
+    aDesc.AppendLiteral(" reporters");
+  }
+  return NS_OK;
+}
+
+NS_STATUS_REPORTER_IMPLEMENT(StatusReporter, "StatusReporter State", getStatus)
+
+#define DUMP(o, s) \
+  do { \
+    const char* s2 = (s); \
+    uint32_t dummy; \
+    nsresult rvDump = (o)->Write((s2), strlen(s2), &dummy); \
+    if (NS_WARN_IF(NS_FAILED(rvDump))) \
+      return rvDump; \
+  } while (0)
+
+static nsresult
+DumpReport(nsIFileOutputStream* aOStream, const nsCString& aProcess,
+           const nsCString& aName, const nsCString& aDescription)
+{
+  if (aProcess.IsEmpty()) {
+    int pid = getpid();
+    nsPrintfCString pidStr("PID %u", pid);
+    DUMP(aOStream, "\n  {\n  \"Process\": \"");
+    DUMP(aOStream, pidStr.get());
+  } else {
+    DUMP(aOStream, "\n  {  \"Unknown Process\": \"");
+  }
+
+  DUMP(aOStream, "\",\n  \"Reporter name\": \"");
+  DUMP(aOStream, aName.get());
+
+  DUMP(aOStream, "\",\n  \"Status Description\": [\"");
+  nsCString desc = aDescription;
+  desc.ReplaceSubstring("|", "\",\"");
+  DUMP(aOStream, desc.get());
+
+  DUMP(aOStream, "\"]\n  }");
+
+  return NS_OK;
+}
+
+/**
+ ** nsStatusReporterManager implementation
+ **/
+
+NS_IMPL_ISUPPORTS(nsStatusReporterManager, nsIStatusReporterManager)
+
+nsStatusReporterManager::nsStatusReporterManager()
+{
+}
+
+nsStatusReporterManager::~nsStatusReporterManager()
+{
+}
+
+NS_IMETHODIMP
+nsStatusReporterManager::Init()
+{
+  RegisterReporter(new NS_STATUS_REPORTER_NAME(StatusReporter));
+  gStatusReportProgress = 1;
+
+#ifdef DO_STATUS_REPORT
+  if (FifoWatcher::MaybeCreate()) {
+    FifoWatcher* fw = FifoWatcher::GetSingleton();
+    fw->RegisterCallback(NS_LITERAL_CSTRING("status report"), doStatusReport);
+  }
+#endif
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStatusReporterManager::DumpReports()
+{
+  static unsigned number = 1;
+  nsresult rv;
+
+  nsCString filename("status-reports-");
+  filename.AppendInt(getpid());
+  filename.Append('-');
+  filename.AppendInt(number++);
+  filename.AppendLiteral(".json");
+
+  // Open a file in NS_OS_TEMP_DIR for writing.
+  // The file is initialized as "incomplete-status-reports-pid-number.json" in the
+  // begining, it will be rename as "status-reports-pid-number.json" in the end.
+  nsCOMPtr<nsIFile> tmpFile;
+  rv = nsDumpUtils::OpenTempFile(NS_LITERAL_CSTRING("incomplete-") +
+                                 filename,
+                                 getter_AddRefs(tmpFile),
+                                 NS_LITERAL_CSTRING("status-reports"));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  nsCOMPtr<nsIFileOutputStream> ostream =
+    do_CreateInstance("@mozilla.org/network/file-output-stream;1");
+  rv = ostream->Init(tmpFile, -1, -1, 0);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  //Write the reports to the file
+
+  DUMP(ostream, "{\n\"subject\":\"about:service reports\",\n");
+  DUMP(ostream, "\"reporters\": [ ");
+
+  nsCOMPtr<nsISimpleEnumerator> e;
+  bool more, first = true;
+  EnumerateReporters(getter_AddRefs(e));
+  while (NS_SUCCEEDED(e->HasMoreElements(&more)) && more) {
+    nsCOMPtr<nsISupports> supports;
+    e->GetNext(getter_AddRefs(supports));
+    nsCOMPtr<nsIStatusReporter> r = do_QueryInterface(supports);
+
+    nsCString process;
+    rv = r->GetProcess(process);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    nsCString name;
+    rv = r->GetName(name);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    nsCString description;
+    rv = r->GetDescription(description);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    if (first) {
+      first = false;
+    } else {
+      DUMP(ostream, ",");
+    }
+
+    rv = DumpReport(ostream, process, name, description);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+  DUMP(ostream, "\n]\n}\n");
+
+  rv = ostream->Close();
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  // Rename the status reports file
+  nsCOMPtr<nsIFile> srFinalFile;
+  rv = NS_GetSpecialDirectory(NS_OS_TEMP_DIR, getter_AddRefs(srFinalFile));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+#ifdef ANDROID
+  rv = srFinalFile->AppendNative(NS_LITERAL_CSTRING("status-reports"));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+#endif
+
+  rv = srFinalFile->AppendNative(filename);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = srFinalFile->CreateUnique(nsIFile::NORMAL_FILE_TYPE, 0600);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  nsAutoString srActualFinalFilename;
+  rv = srFinalFile->GetLeafName(srActualFinalFilename);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = tmpFile->MoveTo(/* directory */ nullptr, srActualFinalFilename);
+
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStatusReporterManager::EnumerateReporters(nsISimpleEnumerator** aResult)
+{
+  return NS_NewArrayEnumerator(aResult, mReporters);
+}
+
+NS_IMETHODIMP
+nsStatusReporterManager::RegisterReporter(nsIStatusReporter* aReporter)
+{
+  if (mReporters.IndexOf(aReporter) != -1) {
+    return NS_ERROR_FAILURE;
+  }
+
+  mReporters.AppendObject(aReporter);
+  gNumReporters++;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStatusReporterManager::UnregisterReporter(nsIStatusReporter* aReporter)
+{
+  if (!mReporters.RemoveObject(aReporter)) {
+    return NS_ERROR_FAILURE;
+  }
+  gNumReporters--;
+  return NS_OK;
+}
+
+nsresult
+NS_RegisterStatusReporter(nsIStatusReporter* aReporter)
+{
+  nsCOMPtr<nsIStatusReporterManager> mgr =
+    do_GetService("@mozilla.org/status-reporter-manager;1");
+  if (!mgr) {
+    return NS_ERROR_FAILURE;
+  }
+  return mgr->RegisterReporter(aReporter);
+}
+
+nsresult
+NS_UnregisterStatusReporter(nsIStatusReporter* aReporter)
+{
+  nsCOMPtr<nsIStatusReporterManager> mgr =
+    do_GetService("@mozilla.org/status-reporter-manager;1");
+  if (!mgr) {
+    return NS_ERROR_FAILURE;
+  }
+  return mgr->UnregisterReporter(aReporter);
+}
+
+nsresult
+NS_DumpStatusReporter()
+{
+  nsCOMPtr<nsIStatusReporterManager> mgr =
+    do_GetService("@mozilla.org/status-reporter-manager;1");
+  if (!mgr) {
+    return NS_ERROR_FAILURE;
+  }
+  return mgr->DumpReports();
+}
diff --git a/xpcom/base/nsStatusReporterManager.h b/xpcom/base/nsStatusReporterManager.h
new file mode 100644
index 000000000..84427cfcf
--- /dev/null
+++ b/xpcom/base/nsStatusReporterManager.h
@@ -0,0 +1,41 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+#include "nsIStatusReporter.h"
+#include "nsCOMArray.h"
+#include "nsString.h"
+
+class nsStatusReporter final : public nsIStatusReporter
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISTATUSREPORTER
+
+  nsStatusReporter(nsACString& aProcess, nsACString& aDesc);
+
+private:
+  nsCString sProcess;
+  nsCString sName;
+  nsCString sDesc;
+
+  virtual ~nsStatusReporter();
+};
+
+
+class nsStatusReporterManager : public nsIStatusReporterManager
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISTATUSREPORTERMANAGER
+
+  nsStatusReporterManager();
+
+private:
+  nsCOMArray<nsIStatusReporter> mReporters;
+
+  virtual ~nsStatusReporterManager();
+};
diff --git a/xpcom/base/nsSystemInfo.cpp b/xpcom/base/nsSystemInfo.cpp
new file mode 100644
index 000000000..f6d9fd5ad
--- /dev/null
+++ b/xpcom/base/nsSystemInfo.cpp
@@ -0,0 +1,985 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ArrayUtils.h"
+
+#include "nsSystemInfo.h"
+#include "prsystem.h"
+#include "prio.h"
+#include "prprf.h"
+#include "mozilla/SSE.h"
+#include "mozilla/arm.h"
+#include "mozilla/Sprintf.h"
+
+#ifdef XP_WIN
+#include <time.h>
+#include <windows.h>
+#include <winioctl.h>
+#include "base/scoped_handle_win.h"
+#include "nsAppDirectoryServiceDefs.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsDirectoryServiceUtils.h"
+#include "nsIObserverService.h"
+#include "nsWindowsHelpers.h"
+#endif
+
+#ifdef XP_MACOSX
+#include "MacHelpers.h"
+#endif
+
+#ifdef MOZ_WIDGET_GTK
+#include <gtk/gtk.h>
+#include <dlfcn.h>
+#endif
+
+#if defined (XP_LINUX) && !defined (ANDROID)
+#include <unistd.h>
+#include <fstream>
+#include "mozilla/Tokenizer.h"
+#include "nsCharSeparatedTokenizer.h"
+
+#include <map>
+#include <string>
+#endif
+
+#ifdef MOZ_WIDGET_ANDROID
+#include "AndroidBridge.h"
+#include "mozilla/dom/ContentChild.h"
+#endif
+
+#ifdef MOZ_WIDGET_GONK
+#include <sys/system_properties.h>
+#include "mozilla/Preferences.h"
+#include "nsPrintfCString.h"
+#endif
+
+#ifdef ANDROID
+extern "C" {
+NS_EXPORT int android_sdk_version;
+}
+#endif
+
+#ifdef XP_MACOSX
+#include <sys/sysctl.h>
+#endif
+
+#if defined(XP_LINUX) && defined(MOZ_SANDBOX)
+#include "mozilla/SandboxInfo.h"
+#endif
+
+// Slot for NS_InitXPCOM2 to pass information to nsSystemInfo::Init.
+// Only set to nonzero (potentially) if XP_UNIX.  On such systems, the
+// system call to discover the appropriate value is not thread-safe,
+// so we must call it before going multithreaded, but nsSystemInfo::Init
+// only happens well after that point.
+uint32_t nsSystemInfo::gUserUmask = 0;
+
+#if defined (XP_LINUX) && !defined (ANDROID)
+static void
+SimpleParseKeyValuePairs(const std::string& aFilename,
+                         std::map<nsCString, nsCString>& aKeyValuePairs)
+{
+  std::ifstream input(aFilename.c_str());
+  for (std::string line; std::getline(input, line); ) {
+    nsAutoCString key, value;
+
+    nsCCharSeparatedTokenizer tokens(nsDependentCString(line.c_str()), ':');
+    if (tokens.hasMoreTokens()) {
+      key = tokens.nextToken();
+      if (tokens.hasMoreTokens()) {
+        value = tokens.nextToken();
+      }
+      // We want the value even if there was just one token, to cover the
+      // case where we had the key, and the value was blank (seems to be
+      // a valid scenario some files.)
+      aKeyValuePairs[key] = value;
+    }
+  }
+}
+#endif
+
+#if defined(XP_WIN)
+namespace {
+nsresult
+GetHDDInfo(const char* aSpecialDirName, nsAutoCString& aModel,
+           nsAutoCString& aRevision)
+{
+  aModel.Truncate();
+  aRevision.Truncate();
+
+  nsCOMPtr<nsIFile> profDir;
+  nsresult rv = NS_GetSpecialDirectory(aSpecialDirName,
+                                       getter_AddRefs(profDir));
+  NS_ENSURE_SUCCESS(rv, rv);
+  nsAutoString profDirPath;
+  rv = profDir->GetPath(profDirPath);
+  NS_ENSURE_SUCCESS(rv, rv);
+  wchar_t volumeMountPoint[MAX_PATH] = {L'\\', L'\\', L'.', L'\\'};
+  const size_t PREFIX_LEN = 4;
+  if (!::GetVolumePathNameW(profDirPath.get(), volumeMountPoint + PREFIX_LEN,
+                            mozilla::ArrayLength(volumeMountPoint) -
+                            PREFIX_LEN)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  size_t volumeMountPointLen = wcslen(volumeMountPoint);
+  // Since we would like to open a drive and not a directory, we need to
+  // remove any trailing backslash. A drive handle is valid for
+  // DeviceIoControl calls, a directory handle is not.
+  if (volumeMountPoint[volumeMountPointLen - 1] == L'\\') {
+    volumeMountPoint[volumeMountPointLen - 1] = L'\0';
+  }
+  ScopedHandle handle(::CreateFileW(volumeMountPoint, 0,
+                                    FILE_SHARE_READ | FILE_SHARE_WRITE,
+                                    nullptr, OPEN_EXISTING, 0, nullptr));
+  if (!handle.IsValid()) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  STORAGE_PROPERTY_QUERY queryParameters = {
+    StorageDeviceProperty, PropertyStandardQuery
+  };
+  STORAGE_DEVICE_DESCRIPTOR outputHeader = {sizeof(STORAGE_DEVICE_DESCRIPTOR)};
+  DWORD bytesRead = 0;
+  if (!::DeviceIoControl(handle, IOCTL_STORAGE_QUERY_PROPERTY,
+                         &queryParameters, sizeof(queryParameters),
+                         &outputHeader, sizeof(outputHeader), &bytesRead,
+                         nullptr)) {
+    return NS_ERROR_FAILURE;
+  }
+  PSTORAGE_DEVICE_DESCRIPTOR deviceOutput =
+    (PSTORAGE_DEVICE_DESCRIPTOR)malloc(outputHeader.Size);
+  if (!::DeviceIoControl(handle, IOCTL_STORAGE_QUERY_PROPERTY,
+                         &queryParameters, sizeof(queryParameters),
+                         deviceOutput, outputHeader.Size, &bytesRead,
+                         nullptr)) {
+    free(deviceOutput);
+    return NS_ERROR_FAILURE;
+  }
+  // Some HDDs are including product ID info in the vendor field. Since PNP
+  // IDs include vendor info and product ID concatenated together, we'll do
+  // that here and interpret the result as a unique ID for the HDD model.
+  if (deviceOutput->VendorIdOffset) {
+    aModel = reinterpret_cast<char*>(deviceOutput) +
+      deviceOutput->VendorIdOffset;
+  }
+  if (deviceOutput->ProductIdOffset) {
+    aModel += reinterpret_cast<char*>(deviceOutput) +
+      deviceOutput->ProductIdOffset;
+  }
+  aModel.CompressWhitespace();
+  if (deviceOutput->ProductRevisionOffset) {
+    aRevision = reinterpret_cast<char*>(deviceOutput) +
+      deviceOutput->ProductRevisionOffset;
+    aRevision.CompressWhitespace();
+  }
+  free(deviceOutput);
+  return NS_OK;
+}
+
+nsresult GetInstallYear(uint32_t& aYear)
+{
+  HKEY hKey;
+  LONG status = RegOpenKeyExW(HKEY_LOCAL_MACHINE,
+                              NS_LITERAL_STRING(
+                              "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion"
+                              ).get(),
+                              0, KEY_READ | KEY_WOW64_64KEY, &hKey);
+
+  if (status != ERROR_SUCCESS) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  nsAutoRegKey key(hKey);
+
+  DWORD type = 0;
+  time_t raw_time = 0;
+  DWORD time_size = sizeof(time_t);
+
+  status = RegQueryValueExW(hKey, L"InstallDate",
+                            nullptr, &type, (LPBYTE)&raw_time, &time_size);
+
+  if (status != ERROR_SUCCESS) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (type != REG_DWORD) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  tm time;
+  if (localtime_s(&time, &raw_time) != 0) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  aYear = 1900UL + time.tm_year;
+  return NS_OK;
+}
+
+nsresult GetCountryCode(nsAString& aCountryCode)
+{
+  GEOID geoid = GetUserGeoID(GEOCLASS_NATION);
+  if (geoid == GEOID_NOT_AVAILABLE) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+  // Get required length
+  int numChars = GetGeoInfoW(geoid, GEO_ISO2, nullptr, 0, 0);
+  if (!numChars) {
+    return NS_ERROR_FAILURE;
+  }
+  // Now get the string for real
+  aCountryCode.SetLength(numChars);
+  numChars = GetGeoInfoW(geoid, GEO_ISO2, wwc(aCountryCode.BeginWriting()),
+                         aCountryCode.Length(), 0);
+  if (!numChars) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // numChars includes null terminator
+  aCountryCode.Truncate(numChars - 1);
+  return NS_OK;
+}
+
+} // namespace
+#endif // defined(XP_WIN)
+
+using namespace mozilla;
+
+nsSystemInfo::nsSystemInfo()
+{
+}
+
+nsSystemInfo::~nsSystemInfo()
+{
+}
+
+// CPU-specific information.
+static const struct PropItems
+{
+  const char* name;
+  bool (*propfun)(void);
+} cpuPropItems[] = {
+  // x86-specific bits.
+  { "hasMMX", mozilla::supports_mmx },
+  { "hasSSE", mozilla::supports_sse },
+  { "hasSSE2", mozilla::supports_sse2 },
+  { "hasSSE3", mozilla::supports_sse3 },
+  { "hasSSSE3", mozilla::supports_ssse3 },
+  { "hasSSE4A", mozilla::supports_sse4a },
+  { "hasSSE4_1", mozilla::supports_sse4_1 },
+  { "hasSSE4_2", mozilla::supports_sse4_2 },
+  { "hasAVX", mozilla::supports_avx },
+  { "hasAVX2", mozilla::supports_avx2 },
+  // ARM-specific bits.
+  { "hasEDSP", mozilla::supports_edsp },
+  { "hasARMv6", mozilla::supports_armv6 },
+  { "hasARMv7", mozilla::supports_armv7 },
+  { "hasNEON", mozilla::supports_neon }
+};
+
+#ifdef XP_WIN
+// Lifted from media/webrtc/trunk/webrtc/base/systeminfo.cc,
+// so keeping the _ instead of switching to camel case for now.
+typedef BOOL (WINAPI *LPFN_GLPI)(
+    PSYSTEM_LOGICAL_PROCESSOR_INFORMATION,
+    PDWORD);
+static void
+GetProcessorInformation(int* physical_cpus, int* cache_size_L2, int* cache_size_L3)
+{
+  MOZ_ASSERT(physical_cpus && cache_size_L2 && cache_size_L3);
+
+  *physical_cpus = 0;
+  *cache_size_L2 = 0; // This will be in kbytes
+  *cache_size_L3 = 0; // This will be in kbytes
+
+  // GetLogicalProcessorInformation() is available on Windows XP SP3 and beyond.
+  LPFN_GLPI glpi = reinterpret_cast<LPFN_GLPI>(GetProcAddress(
+      GetModuleHandle(L"kernel32"),
+      "GetLogicalProcessorInformation"));
+  if (nullptr == glpi) {
+    return;
+  }
+  // Determine buffer size, allocate and get processor information.
+  // Size can change between calls (unlikely), so a loop is done.
+  SYSTEM_LOGICAL_PROCESSOR_INFORMATION info_buffer[32];
+  SYSTEM_LOGICAL_PROCESSOR_INFORMATION* infos = &info_buffer[0];
+  DWORD return_length = sizeof(info_buffer);
+  while (!glpi(infos, &return_length)) {
+    if (GetLastError() == ERROR_INSUFFICIENT_BUFFER && infos == &info_buffer[0]) {
+      infos = new SYSTEM_LOGICAL_PROCESSOR_INFORMATION[return_length / sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION)];
+    } else {
+      return;
+    }
+  }
+
+  for (size_t i = 0;
+      i < return_length / sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION); ++i) {
+    if (infos[i].Relationship == RelationProcessorCore) {
+      ++*physical_cpus;
+    } else if (infos[i].Relationship == RelationCache) {
+      // Only care about L2 and L3 cache
+      switch (infos[i].Cache.Level) {
+        case 2:
+          *cache_size_L2 = static_cast<int>(infos[i].Cache.Size/1024);
+          break;
+        case 3:
+          *cache_size_L3 = static_cast<int>(infos[i].Cache.Size/1024);
+          break;
+        default:
+          break;
+      }
+    }
+  }
+  if (infos != &info_buffer[0]) {
+    delete [] infos;
+  }
+  return;
+}
+#endif
+
+nsresult
+nsSystemInfo::Init()
+{
+  nsresult rv;
+
+  static const struct
+  {
+    PRSysInfo cmd;
+    const char* name;
+  } items[] = {
+    { PR_SI_SYSNAME, "name" },
+    { PR_SI_HOSTNAME, "host" },
+    { PR_SI_ARCHITECTURE, "arch" },
+    { PR_SI_RELEASE, "version" }
+  };
+
+  for (uint32_t i = 0; i < (sizeof(items) / sizeof(items[0])); i++) {
+    char buf[SYS_INFO_BUFFER_LENGTH];
+    if (PR_GetSystemInfo(items[i].cmd, buf, sizeof(buf)) == PR_SUCCESS) {
+      rv = SetPropertyAsACString(NS_ConvertASCIItoUTF16(items[i].name),
+                                 nsDependentCString(buf));
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        return rv;
+      }
+    } else {
+      NS_WARNING("PR_GetSystemInfo failed");
+    }
+  }
+
+  rv = SetPropertyAsBool(NS_ConvertASCIItoUTF16("hasWindowsTouchInterface"),
+                         false);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Additional informations not available through PR_GetSystemInfo.
+  SetInt32Property(NS_LITERAL_STRING("pagesize"), PR_GetPageSize());
+  SetInt32Property(NS_LITERAL_STRING("pageshift"), PR_GetPageShift());
+  SetInt32Property(NS_LITERAL_STRING("memmapalign"), PR_GetMemMapAlignment());
+  SetUint64Property(NS_LITERAL_STRING("memsize"), PR_GetPhysicalMemorySize());
+  SetUint32Property(NS_LITERAL_STRING("umask"), nsSystemInfo::gUserUmask);
+
+  uint64_t virtualMem = 0;
+  nsAutoCString cpuVendor;
+  int cpuSpeed = -1;
+  int cpuFamily = -1;
+  int cpuModel = -1;
+  int cpuStepping = -1;
+  int logicalCPUs = -1;
+  int physicalCPUs = -1;
+  int cacheSizeL2 = -1;
+  int cacheSizeL3 = -1;
+
+#if defined (XP_WIN)
+  // Virtual memory:
+  MEMORYSTATUSEX memStat;
+  memStat.dwLength = sizeof(memStat);
+  if (GlobalMemoryStatusEx(&memStat)) {
+    virtualMem = memStat.ullTotalVirtual;
+  }
+
+  // CPU speed
+  HKEY key;
+  static const WCHAR keyName[] =
+    L"HARDWARE\\DESCRIPTION\\System\\CentralProcessor\\0";
+
+  if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, keyName , 0, KEY_QUERY_VALUE, &key)
+      == ERROR_SUCCESS) {
+    DWORD data, len, vtype;
+    len = sizeof(data);
+
+    if (RegQueryValueEx(key, L"~Mhz", 0, 0, reinterpret_cast<LPBYTE>(&data),
+                        &len) == ERROR_SUCCESS) {
+      cpuSpeed = static_cast<int>(data);
+    }
+
+    // Limit to 64 double byte characters, should be plenty, but create
+    // a buffer one larger as the result may not be null terminated. If
+    // it is more than 64, we will not get the value.
+    wchar_t cpuVendorStr[64+1];
+    len = sizeof(cpuVendorStr)-2;
+    if (RegQueryValueExW(key, L"VendorIdentifier",
+                         0, &vtype,
+                         reinterpret_cast<LPBYTE>(cpuVendorStr),
+                         &len) == ERROR_SUCCESS &&
+        vtype == REG_SZ && len % 2 == 0 && len > 1) {
+      cpuVendorStr[len/2] = 0; // In case it isn't null terminated
+      CopyUTF16toUTF8(nsDependentString(cpuVendorStr), cpuVendor);
+    }
+
+    RegCloseKey(key);
+  }
+
+  // Other CPU attributes:
+  SYSTEM_INFO si;
+  GetNativeSystemInfo(&si);
+  logicalCPUs = si.dwNumberOfProcessors;
+  GetProcessorInformation(&physicalCPUs, &cacheSizeL2, &cacheSizeL3);
+  if (physicalCPUs <= 0) {
+    physicalCPUs = logicalCPUs;
+  }
+  cpuFamily = si.wProcessorLevel;
+  cpuModel = si.wProcessorRevision >> 8;
+  cpuStepping = si.wProcessorRevision & 0xFF;
+#elif defined (XP_MACOSX)
+  // CPU speed
+  uint64_t sysctlValue64 = 0;
+  uint32_t sysctlValue32 = 0;
+  size_t len = 0;
+  len = sizeof(sysctlValue64);
+  if (!sysctlbyname("hw.cpufrequency_max", &sysctlValue64, &len, NULL, 0)) {
+    cpuSpeed = static_cast<int>(sysctlValue64/1000000);
+  }
+  MOZ_ASSERT(sizeof(sysctlValue64) == len);
+
+  len = sizeof(sysctlValue32);
+  if (!sysctlbyname("hw.physicalcpu_max", &sysctlValue32, &len, NULL, 0)) {
+    physicalCPUs = static_cast<int>(sysctlValue32);
+  }
+  MOZ_ASSERT(sizeof(sysctlValue32) == len);
+
+  len = sizeof(sysctlValue32);
+  if (!sysctlbyname("hw.logicalcpu_max", &sysctlValue32, &len, NULL, 0)) {
+    logicalCPUs = static_cast<int>(sysctlValue32);
+  }
+  MOZ_ASSERT(sizeof(sysctlValue32) == len);
+
+  len = sizeof(sysctlValue64);
+  if (!sysctlbyname("hw.l2cachesize", &sysctlValue64, &len, NULL, 0)) {
+    cacheSizeL2 = static_cast<int>(sysctlValue64/1024);
+  }
+  MOZ_ASSERT(sizeof(sysctlValue64) == len);
+
+  len = sizeof(sysctlValue64);
+  if (!sysctlbyname("hw.l3cachesize", &sysctlValue64, &len, NULL, 0)) {
+    cacheSizeL3 = static_cast<int>(sysctlValue64/1024);
+  }
+  MOZ_ASSERT(sizeof(sysctlValue64) == len);
+
+  if (!sysctlbyname("machdep.cpu.vendor", NULL, &len, NULL, 0)) {
+    char* cpuVendorStr = new char[len];
+    if (!sysctlbyname("machdep.cpu.vendor", cpuVendorStr, &len, NULL, 0)) {
+      cpuVendor = cpuVendorStr;
+    }
+    delete [] cpuVendorStr;
+  }
+
+  len = sizeof(sysctlValue32);
+  if (!sysctlbyname("machdep.cpu.family", &sysctlValue32, &len, NULL, 0)) {
+    cpuFamily = static_cast<int>(sysctlValue32);
+  }
+  MOZ_ASSERT(sizeof(sysctlValue32) == len);
+
+  len = sizeof(sysctlValue32);
+  if (!sysctlbyname("machdep.cpu.model", &sysctlValue32, &len, NULL, 0)) {
+    cpuModel = static_cast<int>(sysctlValue32);
+  }
+  MOZ_ASSERT(sizeof(sysctlValue32) == len);
+
+  len = sizeof(sysctlValue32);
+  if (!sysctlbyname("machdep.cpu.stepping", &sysctlValue32, &len, NULL, 0)) {
+    cpuStepping = static_cast<int>(sysctlValue32);
+  }
+  MOZ_ASSERT(sizeof(sysctlValue32) == len);
+
+#elif defined (XP_LINUX) && !defined (ANDROID)
+  // Get vendor, family, model, stepping, physical cores, L3 cache size
+  // from /proc/cpuinfo file
+  {
+    std::map<nsCString, nsCString> keyValuePairs;
+    SimpleParseKeyValuePairs("/proc/cpuinfo", keyValuePairs);
+
+    // cpuVendor from "vendor_id"
+    cpuVendor.Assign(keyValuePairs[NS_LITERAL_CSTRING("vendor_id")]);
+
+    {
+      // cpuFamily from "cpu family"
+      Tokenizer::Token t;
+      Tokenizer p(keyValuePairs[NS_LITERAL_CSTRING("cpu family")]);
+      if (p.Next(t) && t.Type() == Tokenizer::TOKEN_INTEGER &&
+          t.AsInteger() <= INT32_MAX) {
+        cpuFamily = static_cast<int>(t.AsInteger());
+      }
+    }
+
+    {
+      // cpuModel from "model"
+      Tokenizer::Token t;
+      Tokenizer p(keyValuePairs[NS_LITERAL_CSTRING("model")]);
+      if (p.Next(t) && t.Type() == Tokenizer::TOKEN_INTEGER &&
+          t.AsInteger() <= INT32_MAX) {
+        cpuModel = static_cast<int>(t.AsInteger());
+      }
+    }
+
+    {
+      // cpuStepping from "stepping"
+      Tokenizer::Token t;
+      Tokenizer p(keyValuePairs[NS_LITERAL_CSTRING("stepping")]);
+      if (p.Next(t) && t.Type() == Tokenizer::TOKEN_INTEGER &&
+          t.AsInteger() <= INT32_MAX) {
+        cpuStepping = static_cast<int>(t.AsInteger());
+      }
+    }
+
+    {
+      // physicalCPUs from "cpu cores"
+      Tokenizer::Token t;
+      Tokenizer p(keyValuePairs[NS_LITERAL_CSTRING("cpu cores")]);
+      if (p.Next(t) && t.Type() == Tokenizer::TOKEN_INTEGER &&
+          t.AsInteger() <= INT32_MAX) {
+        physicalCPUs = static_cast<int>(t.AsInteger());
+      }
+    }
+
+    {
+      // cacheSizeL3 from "cache size"
+      Tokenizer::Token t;
+      Tokenizer p(keyValuePairs[NS_LITERAL_CSTRING("cache size")]);
+      if (p.Next(t) && t.Type() == Tokenizer::TOKEN_INTEGER &&
+          t.AsInteger() <= INT32_MAX) {
+        cacheSizeL3 = static_cast<int>(t.AsInteger());
+        if (p.Next(t) && t.Type() == Tokenizer::TOKEN_WORD &&
+            t.AsString() != NS_LITERAL_CSTRING("KB")) {
+          // If we get here, there was some text after the cache size value
+          // and that text was not KB.  For now, just don't report the
+          // L3 cache.
+          cacheSizeL3 = -1;
+        }
+      }
+    }
+  }
+
+  {
+    // Get cpuSpeed from another file.
+    std::ifstream input("/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq");
+    std::string line;
+    if (getline(input, line)) {
+      Tokenizer::Token t;
+      Tokenizer p(line.c_str());
+      if (p.Next(t) && t.Type() == Tokenizer::TOKEN_INTEGER &&
+          t.AsInteger() <= INT32_MAX) {
+        cpuSpeed = static_cast<int>(t.AsInteger()/1000);
+      }
+    }
+  }
+
+  {
+    // Get cacheSizeL2 from yet another file
+    std::ifstream input("/sys/devices/system/cpu/cpu0/cache/index2/size");
+    std::string line;
+    if (getline(input, line)) {
+      Tokenizer::Token t;
+      Tokenizer p(line.c_str(), nullptr, "K");
+      if (p.Next(t) && t.Type() == Tokenizer::TOKEN_INTEGER &&
+          t.AsInteger() <= INT32_MAX) {
+        cacheSizeL2 = static_cast<int>(t.AsInteger());
+      }
+    }
+  }
+
+  SetInt32Property(NS_LITERAL_STRING("cpucount"), PR_GetNumberOfProcessors());
+#else
+  SetInt32Property(NS_LITERAL_STRING("cpucount"), PR_GetNumberOfProcessors());
+#endif
+
+  if (virtualMem) SetUint64Property(NS_LITERAL_STRING("virtualmemsize"), virtualMem);
+  if (cpuSpeed >= 0) SetInt32Property(NS_LITERAL_STRING("cpuspeed"), cpuSpeed);
+  if (!cpuVendor.IsEmpty()) SetPropertyAsACString(NS_LITERAL_STRING("cpuvendor"), cpuVendor);
+  if (cpuFamily >= 0) SetInt32Property(NS_LITERAL_STRING("cpufamily"), cpuFamily);
+  if (cpuModel >= 0) SetInt32Property(NS_LITERAL_STRING("cpumodel"), cpuModel);
+  if (cpuStepping >= 0) SetInt32Property(NS_LITERAL_STRING("cpustepping"), cpuStepping);
+
+  if (logicalCPUs >= 0) SetInt32Property(NS_LITERAL_STRING("cpucount"), logicalCPUs);
+  if (physicalCPUs >= 0) SetInt32Property(NS_LITERAL_STRING("cpucores"), physicalCPUs);
+
+  if (cacheSizeL2 >= 0) SetInt32Property(NS_LITERAL_STRING("cpucachel2"), cacheSizeL2);
+  if (cacheSizeL3 >= 0) SetInt32Property(NS_LITERAL_STRING("cpucachel3"), cacheSizeL3);
+
+  for (uint32_t i = 0; i < ArrayLength(cpuPropItems); i++) {
+    rv = SetPropertyAsBool(NS_ConvertASCIItoUTF16(cpuPropItems[i].name),
+                           cpuPropItems[i].propfun());
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+#ifdef XP_WIN
+  BOOL isWow64;
+  BOOL gotWow64Value = IsWow64Process(GetCurrentProcess(), &isWow64);
+  NS_WARNING_ASSERTION(gotWow64Value, "IsWow64Process failed");
+  if (gotWow64Value) {
+    rv = SetPropertyAsBool(NS_LITERAL_STRING("isWow64"), !!isWow64);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+  if (NS_FAILED(GetProfileHDDInfo())) {
+    // We might have been called before profile-do-change. We'll observe that
+    // event so that we can fill this in later.
+    nsCOMPtr<nsIObserverService> obsService =
+      do_GetService(NS_OBSERVERSERVICE_CONTRACTID, &rv);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+    rv = obsService->AddObserver(this, "profile-do-change", false);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+  }
+  nsAutoCString hddModel, hddRevision;
+  if (NS_SUCCEEDED(GetHDDInfo(NS_GRE_DIR, hddModel, hddRevision))) {
+    rv = SetPropertyAsACString(NS_LITERAL_STRING("binHDDModel"), hddModel);
+    NS_ENSURE_SUCCESS(rv, rv);
+    rv = SetPropertyAsACString(NS_LITERAL_STRING("binHDDRevision"),
+                               hddRevision);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+  if (NS_SUCCEEDED(GetHDDInfo(NS_WIN_WINDOWS_DIR, hddModel, hddRevision))) {
+    rv = SetPropertyAsACString(NS_LITERAL_STRING("winHDDModel"), hddModel);
+    NS_ENSURE_SUCCESS(rv, rv);
+    rv = SetPropertyAsACString(NS_LITERAL_STRING("winHDDRevision"),
+                               hddRevision);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  nsAutoString countryCode;
+  if (NS_SUCCEEDED(GetCountryCode(countryCode))) {
+    rv = SetPropertyAsAString(NS_LITERAL_STRING("countryCode"), countryCode);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  uint32_t installYear = 0;
+  if (NS_SUCCEEDED(GetInstallYear(installYear))) {
+    rv = SetPropertyAsUint32(NS_LITERAL_STRING("installYear"), installYear);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+#endif
+
+#if defined(XP_MACOSX)
+  nsAutoString countryCode;
+  if (NS_SUCCEEDED(GetSelectedCityInfo(countryCode))) {
+    rv = SetPropertyAsAString(NS_LITERAL_STRING("countryCode"), countryCode);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+#endif
+
+#if defined(MOZ_WIDGET_GTK)
+  // This must be done here because NSPR can only separate OS's when compiled, not libraries.
+  // 64 bytes is going to be well enough for "GTK " followed by 3 integers
+  // separated with dots.
+  char gtkver[64];
+  ssize_t gtkver_len = 0;
+
+#if MOZ_WIDGET_GTK == 2
+  extern int gtk_read_end_of_the_pipe;
+
+  if (gtk_read_end_of_the_pipe != -1) {
+    do {
+      gtkver_len = read(gtk_read_end_of_the_pipe, &gtkver, sizeof(gtkver));
+    } while (gtkver_len < 0 && errno == EINTR);
+    close(gtk_read_end_of_the_pipe);
+  }
+#endif
+
+  if (gtkver_len <= 0) {
+    gtkver_len = SprintfLiteral(gtkver, "GTK %u.%u.%u", gtk_major_version,
+                                gtk_minor_version, gtk_micro_version);
+  }
+
+  nsAutoCString secondaryLibrary;
+  if (gtkver_len > 0 && gtkver_len < int(sizeof(gtkver))) {
+    secondaryLibrary.Append(nsDependentCSubstring(gtkver, gtkver_len));
+  }
+
+  void* libpulse = dlopen("libpulse.so.0", RTLD_LAZY);
+  const char* libpulseVersion = "not-available";
+  if (libpulse) {
+    auto pa_get_library_version = reinterpret_cast<const char* (*)()>
+      (dlsym(libpulse, "pa_get_library_version"));
+
+    if (pa_get_library_version) {
+      libpulseVersion = pa_get_library_version();
+    }
+  }
+
+  secondaryLibrary.AppendPrintf(",libpulse %s", libpulseVersion);
+
+  if (libpulse) {
+    dlclose(libpulse);
+  }
+
+  rv = SetPropertyAsACString(NS_LITERAL_STRING("secondaryLibrary"),
+                             secondaryLibrary);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+#endif
+
+#ifdef MOZ_WIDGET_ANDROID
+  AndroidSystemInfo info;
+  if (XRE_IsContentProcess()) {
+    dom::ContentChild* child = dom::ContentChild::GetSingleton();
+    if (child) {
+      child->SendGetAndroidSystemInfo(&info);
+      SetupAndroidInfo(info);
+    }
+  } else {
+    GetAndroidSystemInfo(&info);
+    SetupAndroidInfo(info);
+  }
+#endif
+
+#ifdef MOZ_WIDGET_GONK
+  char sdk[PROP_VALUE_MAX];
+  if (__system_property_get("ro.build.version.sdk", sdk)) {
+    android_sdk_version = atoi(sdk);
+    SetPropertyAsInt32(NS_LITERAL_STRING("sdk_version"), android_sdk_version);
+
+    SetPropertyAsACString(NS_LITERAL_STRING("secondaryLibrary"),
+                          nsPrintfCString("SDK %u", android_sdk_version));
+  }
+
+  char characteristics[PROP_VALUE_MAX];
+  if (__system_property_get("ro.build.characteristics", characteristics)) {
+    if (!strcmp(characteristics, "tablet")) {
+      SetPropertyAsBool(NS_LITERAL_STRING("tablet"), true);
+    } else if (!strcmp(characteristics, "tv")) {
+      SetPropertyAsBool(NS_LITERAL_STRING("tv"), true);
+    }
+  }
+
+  nsAutoString str;
+  rv = GetPropertyAsAString(NS_LITERAL_STRING("version"), str);
+  if (NS_SUCCEEDED(rv)) {
+    SetPropertyAsAString(NS_LITERAL_STRING("kernel_version"), str);
+  }
+
+  const nsAdoptingString& b2g_os_name =
+    mozilla::Preferences::GetString("b2g.osName");
+  if (b2g_os_name) {
+    SetPropertyAsAString(NS_LITERAL_STRING("name"), b2g_os_name);
+  }
+
+  const nsAdoptingString& b2g_version =
+    mozilla::Preferences::GetString("b2g.version");
+  if (b2g_version) {
+    SetPropertyAsAString(NS_LITERAL_STRING("version"), b2g_version);
+  }
+#endif
+
+#if defined(XP_LINUX) && defined(MOZ_SANDBOX)
+  SandboxInfo sandInfo = SandboxInfo::Get();
+
+  SetPropertyAsBool(NS_LITERAL_STRING("hasSeccompBPF"),
+                    sandInfo.Test(SandboxInfo::kHasSeccompBPF));
+  SetPropertyAsBool(NS_LITERAL_STRING("hasSeccompTSync"),
+                    sandInfo.Test(SandboxInfo::kHasSeccompTSync));
+  SetPropertyAsBool(NS_LITERAL_STRING("hasUserNamespaces"),
+                    sandInfo.Test(SandboxInfo::kHasUserNamespaces));
+  SetPropertyAsBool(NS_LITERAL_STRING("hasPrivilegedUserNamespaces"),
+                    sandInfo.Test(SandboxInfo::kHasPrivilegedUserNamespaces));
+
+  if (sandInfo.Test(SandboxInfo::kEnabledForContent)) {
+    SetPropertyAsBool(NS_LITERAL_STRING("canSandboxContent"),
+                      sandInfo.CanSandboxContent());
+  }
+
+  if (sandInfo.Test(SandboxInfo::kEnabledForMedia)) {
+    SetPropertyAsBool(NS_LITERAL_STRING("canSandboxMedia"),
+                      sandInfo.CanSandboxMedia());
+  }
+#endif // XP_LINUX && MOZ_SANDBOX
+
+  return NS_OK;
+}
+
+#ifdef MOZ_WIDGET_ANDROID
+// Prerelease versions of Android use a letter instead of version numbers.
+// Unfortunately this breaks websites due to the user agent.
+// Chrome works around this by hardcoding an Android version when a
+// numeric version can't be obtained. We're doing the same.
+// This version will need to be updated whenever there is a new official
+// Android release.
+// See: https://cs.chromium.org/chromium/src/base/sys_info_android.cc?l=61
+#define DEFAULT_ANDROID_VERSION "6.0.99"
+
+/* static */
+void
+nsSystemInfo::GetAndroidSystemInfo(AndroidSystemInfo* aInfo)
+{
+  MOZ_ASSERT(XRE_IsParentProcess());
+
+  if (!mozilla::AndroidBridge::Bridge()) {
+    aInfo->sdk_version() = 0;
+    return;
+  }
+
+  nsAutoString str;
+  if (mozilla::AndroidBridge::Bridge()->GetStaticStringField(
+      "android/os/Build", "MODEL", str)) {
+    aInfo->device() = str;
+  }
+  if (mozilla::AndroidBridge::Bridge()->GetStaticStringField(
+      "android/os/Build", "MANUFACTURER", str)) {
+    aInfo->manufacturer() = str;
+  }
+  if (mozilla::AndroidBridge::Bridge()->GetStaticStringField(
+      "android/os/Build$VERSION", "RELEASE", str)) {
+    int major_version;
+    int minor_version;
+    int bugfix_version;
+    int num_read = sscanf(NS_ConvertUTF16toUTF8(str).get(), "%d.%d.%d", &major_version, &minor_version, &bugfix_version);
+    if (num_read == 0) {
+      aInfo->release_version() = NS_LITERAL_STRING(DEFAULT_ANDROID_VERSION);
+    } else {
+      aInfo->release_version() = str;
+    }
+  }
+  if (mozilla::AndroidBridge::Bridge()->GetStaticStringField(
+      "android/os/Build", "HARDWARE", str)) {
+    aInfo->hardware() = str;
+  }
+  int32_t sdk_version;
+  if (!mozilla::AndroidBridge::Bridge()->GetStaticIntField(
+      "android/os/Build$VERSION", "SDK_INT", &sdk_version)) {
+    sdk_version = 0;
+  }
+  aInfo->sdk_version() = sdk_version;
+  aInfo->isTablet() = java::GeckoAppShell::IsTablet();
+}
+
+void
+nsSystemInfo::SetupAndroidInfo(const AndroidSystemInfo& aInfo)
+{
+  if (!aInfo.device().IsEmpty()) {
+    SetPropertyAsAString(NS_LITERAL_STRING("device"), aInfo.device());
+  }
+  if (!aInfo.manufacturer().IsEmpty()) {
+    SetPropertyAsAString(NS_LITERAL_STRING("manufacturer"), aInfo.manufacturer());
+  }
+  if (!aInfo.release_version().IsEmpty()) {
+    SetPropertyAsAString(NS_LITERAL_STRING("release_version"), aInfo.release_version());
+  }
+  SetPropertyAsBool(NS_LITERAL_STRING("tablet"), aInfo.isTablet());
+  // NSPR "version" is the kernel version. For Android we want the Android version.
+  // Rename SDK version to version and put the kernel version into kernel_version.
+  nsAutoString str;
+  nsresult rv = GetPropertyAsAString(NS_LITERAL_STRING("version"), str);
+  if (NS_SUCCEEDED(rv)) {
+    SetPropertyAsAString(NS_LITERAL_STRING("kernel_version"), str);
+  }
+  // When AndroidBridge is not available (eg. in xpcshell tests), sdk_version is 0.
+  if (aInfo.sdk_version() != 0) {
+    android_sdk_version = aInfo.sdk_version();
+    if (android_sdk_version >= 8 && !aInfo.hardware().IsEmpty()) {
+      SetPropertyAsAString(NS_LITERAL_STRING("hardware"), aInfo.hardware());
+    }
+    SetPropertyAsInt32(NS_LITERAL_STRING("version"), android_sdk_version);
+  }
+}
+#endif // MOZ_WIDGET_ANDROID
+
+void
+nsSystemInfo::SetInt32Property(const nsAString& aPropertyName,
+                               const int32_t aValue)
+{
+  NS_WARNING_ASSERTION(aValue > 0, "Unable to read system value");
+  if (aValue > 0) {
+#ifdef DEBUG
+    nsresult rv =
+#endif
+      SetPropertyAsInt32(aPropertyName, aValue);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "Unable to set property");
+  }
+}
+
+void
+nsSystemInfo::SetUint32Property(const nsAString& aPropertyName,
+                                const uint32_t aValue)
+{
+  // Only one property is currently set via this function.
+  // It may legitimately be zero.
+#ifdef DEBUG
+  nsresult rv =
+#endif
+    SetPropertyAsUint32(aPropertyName, aValue);
+  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "Unable to set property");
+}
+
+void
+nsSystemInfo::SetUint64Property(const nsAString& aPropertyName,
+                                const uint64_t aValue)
+{
+  NS_WARNING_ASSERTION(aValue > 0, "Unable to read system value");
+  if (aValue > 0) {
+#ifdef DEBUG
+    nsresult rv =
+#endif
+      SetPropertyAsUint64(aPropertyName, aValue);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "Unable to set property");
+  }
+}
+
+#if defined(XP_WIN)
+NS_IMETHODIMP
+nsSystemInfo::Observe(nsISupports* aSubject, const char* aTopic,
+                      const char16_t* aData)
+{
+  if (!strcmp(aTopic, "profile-do-change")) {
+    nsresult rv;
+    nsCOMPtr<nsIObserverService> obsService =
+      do_GetService(NS_OBSERVERSERVICE_CONTRACTID, &rv);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+    rv = obsService->RemoveObserver(this, "profile-do-change");
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+    return GetProfileHDDInfo();
+  }
+  return NS_OK;
+}
+
+nsresult
+nsSystemInfo::GetProfileHDDInfo()
+{
+  nsAutoCString hddModel, hddRevision;
+  nsresult rv = GetHDDInfo(NS_APP_USER_PROFILE_50_DIR, hddModel, hddRevision);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  rv = SetPropertyAsACString(NS_LITERAL_STRING("profileHDDModel"), hddModel);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  rv = SetPropertyAsACString(NS_LITERAL_STRING("profileHDDRevision"),
+                             hddRevision);
+  return rv;
+}
+
+NS_IMPL_ISUPPORTS_INHERITED(nsSystemInfo, nsHashPropertyBag, nsIObserver)
+#endif // defined(XP_WIN)
+
diff --git a/xpcom/base/nsSystemInfo.h b/xpcom/base/nsSystemInfo.h
new file mode 100644
index 000000000..5a7ef4424
--- /dev/null
+++ b/xpcom/base/nsSystemInfo.h
@@ -0,0 +1,66 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef _NSSYSTEMINFO_H_
+#define _NSSYSTEMINFO_H_
+
+#include "nsHashPropertyBag.h"
+#if defined(XP_WIN)
+#include "nsIObserver.h"
+#endif // defined(XP_WIN)
+
+#ifdef MOZ_WIDGET_ANDROID
+#include "mozilla/dom/PContent.h"
+#endif // MOZ_WIDGET_ANDROID
+
+class nsSystemInfo final
+  : public nsHashPropertyBag
+#if defined(XP_WIN)
+  , public nsIObserver
+#endif // defined(XP_WIN)
+{
+public:
+#if defined(XP_WIN)
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSIOBSERVER
+#endif // defined(XP_WIN)
+
+  nsSystemInfo();
+
+  nsresult Init();
+
+  // Slot for NS_InitXPCOM2 to pass information to nsSystemInfo::Init.
+  // See comments above the variable definition and in NS_InitXPCOM2.
+  static uint32_t gUserUmask;
+
+#ifdef MOZ_WIDGET_ANDROID
+  static void GetAndroidSystemInfo(mozilla::dom::AndroidSystemInfo* aInfo);
+  protected:
+    void SetupAndroidInfo(const mozilla::dom::AndroidSystemInfo&);
+#endif
+
+protected:
+  void SetInt32Property(const nsAString& aPropertyName,
+                        const int32_t aValue);
+  void SetUint32Property(const nsAString& aPropertyName,
+                         const uint32_t aValue);
+  void SetUint64Property(const nsAString& aPropertyName,
+                         const uint64_t aValue);
+
+private:
+  ~nsSystemInfo();
+
+#if defined(XP_WIN)
+  nsresult GetProfileHDDInfo();
+#endif // defined(XP_WIN)
+};
+
+#define NS_SYSTEMINFO_CONTRACTID "@mozilla.org/system-info;1"
+#define NS_SYSTEMINFO_CID \
+{ 0xd962398a, 0x99e5, 0x49b2, \
+{ 0x85, 0x7a, 0xc1, 0x59, 0x04, 0x9c, 0x7f, 0x6c } }
+
+#endif /* _NSSYSTEMINFO_H_ */
diff --git a/xpcom/base/nsTraceRefcnt.cpp b/xpcom/base/nsTraceRefcnt.cpp
new file mode 100644
index 000000000..3b415174b
--- /dev/null
+++ b/xpcom/base/nsTraceRefcnt.cpp
@@ -0,0 +1,1319 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsTraceRefcnt.h"
+#include "mozilla/IntegerPrintfMacros.h"
+#include "mozilla/StaticPtr.h"
+#include "nsXPCOMPrivate.h"
+#include "nscore.h"
+#include "nsISupports.h"
+#include "nsTArray.h"
+#include "nsTHashtable.h"
+#include "prenv.h"
+#include "plstr.h"
+#include "prlink.h"
+#include "nsCRT.h"
+#include <math.h>
+#include "nsHashKeys.h"
+#include "mozilla/StackWalk.h"
+#include "nsThreadUtils.h"
+#include "CodeAddressService.h"
+
+#include "nsXULAppAPI.h"
+#ifdef XP_WIN
+#include <process.h>
+#define getpid _getpid
+#else
+#include <unistd.h>
+#endif
+
+#include "mozilla/Atomics.h"
+#include "mozilla/AutoRestore.h"
+#include "mozilla/BlockingResourceBase.h"
+#include "mozilla/PoisonIOInterposer.h"
+
+#include <string>
+#include <vector>
+
+#ifdef HAVE_DLOPEN
+#include <dlfcn.h>
+#endif
+
+#ifdef MOZ_DMD
+#include "base/process_util.h"
+#include "nsMemoryInfoDumper.h"
+#endif
+
+////////////////////////////////////////////////////////////////////////////////
+
+#include "plhash.h"
+#include "prmem.h"
+
+#include "prthread.h"
+
+// We use a spin lock instead of a regular mutex because this lock is usually
+// only held for a very short time, and gets grabbed at a very high frequency
+// (~100000 times per second). On Mac, the overhead of using a regular lock
+// is very high, see bug 1137963.
+static mozilla::Atomic<uintptr_t, mozilla::ReleaseAcquire> gTraceLogLocked;
+
+struct MOZ_STACK_CLASS AutoTraceLogLock final
+{
+  bool doRelease;
+  AutoTraceLogLock()
+    : doRelease(true)
+  {
+    uintptr_t currentThread = reinterpret_cast<uintptr_t>(PR_GetCurrentThread());
+    if (gTraceLogLocked == currentThread) {
+      doRelease = false;
+    } else {
+      while (!gTraceLogLocked.compareExchange(0, currentThread)) {
+        PR_Sleep(PR_INTERVAL_NO_WAIT); /* yield */
+      }
+    }
+  }
+  ~AutoTraceLogLock() { if (doRelease) gTraceLogLocked = 0; }
+};
+
+static PLHashTable* gBloatView;
+static PLHashTable* gTypesToLog;
+static PLHashTable* gObjectsToLog;
+static PLHashTable* gSerialNumbers;
+static intptr_t gNextSerialNumber;
+static bool gDumpedStatistics = false;
+
+// By default, debug builds only do bloat logging. Bloat logging
+// only tries to record when an object is created or destroyed, so we
+// optimize the common case in NS_LogAddRef and NS_LogRelease where
+// only bloat logging is enabled and no logging needs to be done.
+enum LoggingType
+{
+  NoLogging,
+  OnlyBloatLogging,
+  FullLogging
+};
+
+static LoggingType gLogging;
+
+static bool gLogLeaksOnly;
+
+#define BAD_TLS_INDEX ((unsigned)-1)
+
+// if gActivityTLS == BAD_TLS_INDEX, then we're
+// unitialized... otherwise this points to a NSPR TLS thread index
+// indicating whether addref activity is legal. If the PTR_TO_INT32 is 0 then
+// activity is ok, otherwise not!
+static unsigned gActivityTLS = BAD_TLS_INDEX;
+
+static bool gInitialized;
+static nsrefcnt gInitCount;
+
+static FILE* gBloatLog = nullptr;
+static FILE* gRefcntsLog = nullptr;
+static FILE* gAllocLog = nullptr;
+static FILE* gCOMPtrLog = nullptr;
+
+static void
+WalkTheStackSavingLocations(std::vector<void*>& aLocations);
+
+struct SerialNumberRecord
+{
+  SerialNumberRecord()
+    : serialNumber(++gNextSerialNumber)
+    , refCount(0)
+    , COMPtrCount(0)
+  {}
+
+  intptr_t serialNumber;
+  int32_t refCount;
+  int32_t COMPtrCount;
+  // We use std:: classes here rather than the XPCOM equivalents because the
+  // XPCOM equivalents do leak-checking, and if you try to leak-check while
+  // leak-checking, you're gonna have a bad time.
+  std::vector<void*> allocationStack;
+};
+
+struct nsTraceRefcntStats
+{
+  uint64_t mCreates;
+  uint64_t mDestroys;
+
+  bool HaveLeaks() const
+  {
+    return mCreates != mDestroys;
+  }
+
+  void Clear()
+  {
+    mCreates = 0;
+    mDestroys = 0;
+  }
+
+  int64_t NumLeaked() const
+  {
+    return (int64_t)(mCreates - mDestroys);
+  }
+};
+
+#ifdef DEBUG
+static const char kStaticCtorDtorWarning[] =
+  "XPCOM objects created/destroyed from static ctor/dtor";
+
+static void
+AssertActivityIsLegal()
+{
+  if (gActivityTLS == BAD_TLS_INDEX || PR_GetThreadPrivate(gActivityTLS)) {
+    if (PR_GetEnv("MOZ_FATAL_STATIC_XPCOM_CTORS_DTORS")) {
+      NS_RUNTIMEABORT(kStaticCtorDtorWarning);
+    } else {
+      NS_WARNING(kStaticCtorDtorWarning);
+    }
+  }
+}
+#  define ASSERT_ACTIVITY_IS_LEGAL              \
+  PR_BEGIN_MACRO                                \
+    AssertActivityIsLegal();                    \
+  PR_END_MACRO
+#else
+#  define ASSERT_ACTIVITY_IS_LEGAL PR_BEGIN_MACRO PR_END_MACRO
+#endif // DEBUG
+
+// These functions are copied from nsprpub/lib/ds/plhash.c, with changes
+// to the functions not called Default* to free the SerialNumberRecord or
+// the BloatEntry.
+
+static void*
+DefaultAllocTable(void* aPool, size_t aSize)
+{
+  return PR_MALLOC(aSize);
+}
+
+static void
+DefaultFreeTable(void* aPool, void* aItem)
+{
+  PR_Free(aItem);
+}
+
+static PLHashEntry*
+DefaultAllocEntry(void* aPool, const void* aKey)
+{
+  return PR_NEW(PLHashEntry);
+}
+
+static void
+SerialNumberFreeEntry(void* aPool, PLHashEntry* aHashEntry, unsigned aFlag)
+{
+  if (aFlag == HT_FREE_ENTRY) {
+    delete static_cast<SerialNumberRecord*>(aHashEntry->value);
+    PR_Free(aHashEntry);
+  }
+}
+
+static void
+TypesToLogFreeEntry(void* aPool, PLHashEntry* aHashEntry, unsigned aFlag)
+{
+  if (aFlag == HT_FREE_ENTRY) {
+    free(const_cast<char*>(static_cast<const char*>(aHashEntry->key)));
+    PR_Free(aHashEntry);
+  }
+}
+
+static const PLHashAllocOps serialNumberHashAllocOps = {
+  DefaultAllocTable, DefaultFreeTable,
+  DefaultAllocEntry, SerialNumberFreeEntry
+};
+
+static const PLHashAllocOps typesToLogHashAllocOps = {
+  DefaultAllocTable, DefaultFreeTable,
+  DefaultAllocEntry, TypesToLogFreeEntry
+};
+
+////////////////////////////////////////////////////////////////////////////////
+
+class CodeAddressServiceStringTable final
+{
+public:
+  CodeAddressServiceStringTable() : mSet(32) {}
+
+  const char* Intern(const char* aString)
+  {
+    nsCharPtrHashKey* e = mSet.PutEntry(aString);
+    return e->GetKey();
+  }
+
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return mSet.SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+private:
+  typedef nsTHashtable<nsCharPtrHashKey> StringSet;
+  StringSet mSet;
+};
+
+struct CodeAddressServiceStringAlloc final
+{
+  static char* copy(const char* aStr) { return strdup(aStr); }
+  static void free(char* aPtr) { ::free(aPtr); }
+};
+
+// WalkTheStack does not hold any locks needed by MozDescribeCodeAddress, so
+// this class does not need to do anything.
+struct CodeAddressServiceLock final
+{
+  static void Unlock() {}
+  static void Lock() {}
+  static bool IsLocked() { return true; }
+};
+
+typedef mozilla::CodeAddressService<CodeAddressServiceStringTable,
+                                    CodeAddressServiceStringAlloc,
+                                    CodeAddressServiceLock> WalkTheStackCodeAddressService;
+
+mozilla::StaticAutoPtr<WalkTheStackCodeAddressService> gCodeAddressService;
+
+////////////////////////////////////////////////////////////////////////////////
+
+class BloatEntry
+{
+public:
+  BloatEntry(const char* aClassName, uint32_t aClassSize)
+    : mClassSize(aClassSize)
+  {
+    MOZ_ASSERT(strlen(aClassName) > 0, "BloatEntry name must be non-empty");
+    mClassName = PL_strdup(aClassName);
+    mStats.Clear();
+    mTotalLeaked = 0;
+  }
+
+  ~BloatEntry()
+  {
+    PL_strfree(mClassName);
+  }
+
+  uint32_t GetClassSize()
+  {
+    return (uint32_t)mClassSize;
+  }
+  const char* GetClassName()
+  {
+    return mClassName;
+  }
+
+  void Ctor()
+  {
+    mStats.mCreates++;
+  }
+
+  void Dtor()
+  {
+    mStats.mDestroys++;
+  }
+
+  static int DumpEntry(PLHashEntry* aHashEntry, int aIndex, void* aArg)
+  {
+    BloatEntry* entry = (BloatEntry*)aHashEntry->value;
+    if (entry) {
+      static_cast<nsTArray<BloatEntry*>*>(aArg)->AppendElement(entry);
+    }
+    return HT_ENUMERATE_NEXT;
+  }
+
+  static int TotalEntries(PLHashEntry* aHashEntry, int aIndex, void* aArg)
+  {
+    BloatEntry* entry = (BloatEntry*)aHashEntry->value;
+    if (entry && nsCRT::strcmp(entry->mClassName, "TOTAL") != 0) {
+      entry->Total((BloatEntry*)aArg);
+    }
+    return HT_ENUMERATE_NEXT;
+  }
+
+  void Total(BloatEntry* aTotal)
+  {
+    aTotal->mStats.mCreates += mStats.mCreates;
+    aTotal->mStats.mDestroys += mStats.mDestroys;
+    aTotal->mClassSize += mClassSize * mStats.mCreates;    // adjust for average in DumpTotal
+    aTotal->mTotalLeaked += mClassSize * mStats.NumLeaked();
+  }
+
+  void DumpTotal(FILE* aOut)
+  {
+    mClassSize /= mStats.mCreates;
+    Dump(-1, aOut);
+  }
+
+  bool PrintDumpHeader(FILE* aOut, const char* aMsg)
+  {
+    fprintf(aOut, "\n== BloatView: %s, %s process %d\n", aMsg,
+            XRE_ChildProcessTypeToString(XRE_GetProcessType()), getpid());
+    if (gLogLeaksOnly && !mStats.HaveLeaks()) {
+      return false;
+    }
+
+    fprintf(aOut,
+            "\n" \
+            "     |<----------------Class--------------->|<-----Bytes------>|<----Objects---->|\n" \
+            "     |                                      | Per-Inst   Leaked|   Total      Rem|\n");
+
+    this->DumpTotal(aOut);
+
+    return true;
+  }
+
+  void Dump(int aIndex, FILE* aOut)
+  {
+    if (gLogLeaksOnly && !mStats.HaveLeaks()) {
+      return;
+    }
+
+    if (mStats.HaveLeaks() || mStats.mCreates != 0) {
+      fprintf(aOut, "%4d |%-38.38s| %8d %8" PRId64 "|%8" PRIu64 " %8" PRId64"|\n",
+              aIndex + 1, mClassName,
+              GetClassSize(),
+              nsCRT::strcmp(mClassName, "TOTAL") ? (mStats.NumLeaked() * GetClassSize()) : mTotalLeaked,
+              mStats.mCreates,
+              mStats.NumLeaked());
+    }
+  }
+
+protected:
+  char* mClassName;
+  double mClassSize; // This is stored as a double because of the way we compute the avg class size for total bloat.
+  int64_t mTotalLeaked; // Used only for TOTAL entry.
+  nsTraceRefcntStats mStats;
+};
+
+static void
+BloatViewFreeEntry(void* aPool, PLHashEntry* aHashEntry, unsigned aFlag)
+{
+  if (aFlag == HT_FREE_ENTRY) {
+    BloatEntry* entry = static_cast<BloatEntry*>(aHashEntry->value);
+    delete entry;
+    PR_Free(aHashEntry);
+  }
+}
+
+const static PLHashAllocOps bloatViewHashAllocOps = {
+  DefaultAllocTable, DefaultFreeTable,
+  DefaultAllocEntry, BloatViewFreeEntry
+};
+
+static void
+RecreateBloatView()
+{
+  gBloatView = PL_NewHashTable(256,
+                               PL_HashString,
+                               PL_CompareStrings,
+                               PL_CompareValues,
+                               &bloatViewHashAllocOps, nullptr);
+}
+
+static BloatEntry*
+GetBloatEntry(const char* aTypeName, uint32_t aInstanceSize)
+{
+  if (!gBloatView) {
+    RecreateBloatView();
+  }
+  BloatEntry* entry = nullptr;
+  if (gBloatView) {
+    entry = (BloatEntry*)PL_HashTableLookup(gBloatView, aTypeName);
+    if (!entry && aInstanceSize > 0) {
+
+      entry = new BloatEntry(aTypeName, aInstanceSize);
+      PLHashEntry* e = PL_HashTableAdd(gBloatView, aTypeName, entry);
+      if (!e) {
+        delete entry;
+        entry = nullptr;
+      }
+    } else {
+      MOZ_ASSERT(aInstanceSize == 0 || entry->GetClassSize() == aInstanceSize,
+                 "Mismatched sizes were recorded in the memory leak logging table. "
+                 "The usual cause of this is having a templated class that uses "
+                 "MOZ_COUNT_{C,D}TOR in the constructor or destructor, respectively. "
+                 "As a workaround, the MOZ_COUNT_{C,D}TOR calls can be moved to a "
+                 "non-templated base class.");
+    }
+  }
+  return entry;
+}
+
+static int
+DumpSerialNumbers(PLHashEntry* aHashEntry, int aIndex, void* aClosure)
+{
+  SerialNumberRecord* record =
+    static_cast<SerialNumberRecord*>(aHashEntry->value);
+  auto* outputFile = static_cast<FILE*>(aClosure);
+#ifdef HAVE_CPP_DYNAMIC_CAST_TO_VOID_PTR
+  fprintf(outputFile, "%" PRIdPTR
+          " @%p (%d references; %d from COMPtrs)\n",
+          record->serialNumber,
+          aHashEntry->key,
+          record->refCount,
+          record->COMPtrCount);
+#else
+  fprintf(outputFile, "%" PRIdPTR
+          " @%p (%d references)\n",
+          record->serialNumber,
+          aHashEntry->key,
+          record->refCount);
+#endif
+  if (!record->allocationStack.empty()) {
+    static const size_t bufLen = 1024;
+    char buf[bufLen];
+    fprintf(outputFile, "allocation stack:\n");
+    for (size_t i = 0, length = record->allocationStack.size();
+         i < length;
+         ++i) {
+      gCodeAddressService->GetLocation(i, record->allocationStack[i],
+                                       buf, bufLen);
+      fprintf(outputFile, "%s\n", buf);
+    }
+  }
+  return HT_ENUMERATE_NEXT;
+}
+
+
+template<>
+class nsDefaultComparator<BloatEntry*, BloatEntry*>
+{
+public:
+  bool Equals(BloatEntry* const& aEntry1, BloatEntry* const& aEntry2) const
+  {
+    return PL_strcmp(aEntry1->GetClassName(), aEntry2->GetClassName()) == 0;
+  }
+  bool LessThan(BloatEntry* const& aEntry1, BloatEntry* const& aEntry2) const
+  {
+    return PL_strcmp(aEntry1->GetClassName(), aEntry2->GetClassName()) < 0;
+  }
+};
+
+
+nsresult
+nsTraceRefcnt::DumpStatistics()
+{
+  if (!gBloatLog || !gBloatView) {
+    return NS_ERROR_FAILURE;
+  }
+
+  AutoTraceLogLock lock;
+
+  MOZ_ASSERT(!gDumpedStatistics,
+             "Calling DumpStatistics more than once may result in "
+             "bogus positive or negative leaks being reported");
+  gDumpedStatistics = true;
+
+  // Don't try to log while we hold the lock, we'd deadlock.
+  AutoRestore<LoggingType> saveLogging(gLogging);
+  gLogging = NoLogging;
+
+  BloatEntry total("TOTAL", 0);
+  PL_HashTableEnumerateEntries(gBloatView, BloatEntry::TotalEntries, &total);
+  const char* msg;
+  if (gLogLeaksOnly) {
+    msg = "ALL (cumulative) LEAK STATISTICS";
+  } else {
+    msg = "ALL (cumulative) LEAK AND BLOAT STATISTICS";
+  }
+  const bool leaked = total.PrintDumpHeader(gBloatLog, msg);
+
+  nsTArray<BloatEntry*> entries;
+  PL_HashTableEnumerateEntries(gBloatView, BloatEntry::DumpEntry, &entries);
+  const uint32_t count = entries.Length();
+
+  if (!gLogLeaksOnly || leaked) {
+    // Sort the entries alphabetically by classname.
+    entries.Sort();
+
+    for (uint32_t i = 0; i < count; ++i) {
+      BloatEntry* entry = entries[i];
+      entry->Dump(i, gBloatLog);
+    }
+
+    fprintf(gBloatLog, "\n");
+  }
+
+  fprintf(gBloatLog, "nsTraceRefcnt::DumpStatistics: %d entries\n", count);
+
+  if (gSerialNumbers) {
+    fprintf(gBloatLog, "\nSerial Numbers of Leaked Objects:\n");
+    PL_HashTableEnumerateEntries(gSerialNumbers, DumpSerialNumbers, gBloatLog);
+  }
+
+  return NS_OK;
+}
+
+void
+nsTraceRefcnt::ResetStatistics()
+{
+  AutoTraceLogLock lock;
+  if (gBloatView) {
+    PL_HashTableDestroy(gBloatView);
+    gBloatView = nullptr;
+  }
+}
+
+static bool
+LogThisType(const char* aTypeName)
+{
+  void* he = PL_HashTableLookup(gTypesToLog, aTypeName);
+  return he != nullptr;
+}
+
+static PLHashNumber
+HashNumber(const void* aKey)
+{
+  return PLHashNumber(NS_PTR_TO_INT32(aKey));
+}
+
+static intptr_t
+GetSerialNumber(void* aPtr, bool aCreate)
+{
+  PLHashEntry** hep = PL_HashTableRawLookup(gSerialNumbers,
+                                            HashNumber(aPtr),
+                                            aPtr);
+  if (hep && *hep) {
+    MOZ_RELEASE_ASSERT(!aCreate, "If an object already has a serial number, we should be destroying it.");
+    return static_cast<SerialNumberRecord*>((*hep)->value)->serialNumber;
+  }
+
+  if (!aCreate) {
+    return 0;
+  }
+
+  SerialNumberRecord* record = new SerialNumberRecord();
+  WalkTheStackSavingLocations(record->allocationStack);
+  PL_HashTableRawAdd(gSerialNumbers, hep, HashNumber(aPtr),
+                     aPtr, static_cast<void*>(record));
+  return gNextSerialNumber;
+}
+
+static int32_t*
+GetRefCount(void* aPtr)
+{
+  PLHashEntry** hep = PL_HashTableRawLookup(gSerialNumbers,
+                                            HashNumber(aPtr),
+                                            aPtr);
+  if (hep && *hep) {
+    return &(static_cast<SerialNumberRecord*>((*hep)->value)->refCount);
+  } else {
+    return nullptr;
+  }
+}
+
+#ifdef HAVE_CPP_DYNAMIC_CAST_TO_VOID_PTR
+static int32_t*
+GetCOMPtrCount(void* aPtr)
+{
+  PLHashEntry** hep = PL_HashTableRawLookup(gSerialNumbers,
+                                            HashNumber(aPtr),
+                                            aPtr);
+  if (hep && *hep) {
+    return &(static_cast<SerialNumberRecord*>((*hep)->value)->COMPtrCount);
+  }
+  return nullptr;
+}
+#endif // HAVE_CPP_DYNAMIC_CAST_TO_VOID_PTR
+
+static void
+RecycleSerialNumberPtr(void* aPtr)
+{
+  PL_HashTableRemove(gSerialNumbers, aPtr);
+}
+
+static bool
+LogThisObj(intptr_t aSerialNumber)
+{
+  return (bool)PL_HashTableLookup(gObjectsToLog, (const void*)aSerialNumber);
+}
+
+#ifdef XP_WIN
+#define FOPEN_NO_INHERIT "N"
+#else
+#define FOPEN_NO_INHERIT
+#endif
+
+static bool
+InitLog(const char* aEnvVar, const char* aMsg, FILE** aResult)
+{
+  const char* value = getenv(aEnvVar);
+  if (value) {
+    if (nsCRT::strcmp(value, "1") == 0) {
+      *aResult = stdout;
+      fprintf(stdout, "### %s defined -- logging %s to stdout\n",
+              aEnvVar, aMsg);
+      return true;
+    } else if (nsCRT::strcmp(value, "2") == 0) {
+      *aResult = stderr;
+      fprintf(stdout, "### %s defined -- logging %s to stderr\n",
+              aEnvVar, aMsg);
+      return true;
+    } else {
+      FILE* stream;
+      nsAutoCString fname(value);
+      if (!XRE_IsParentProcess()) {
+        bool hasLogExtension =
+          fname.RFind(".log", true, -1, 4) == kNotFound ? false : true;
+        if (hasLogExtension) {
+          fname.Cut(fname.Length() - 4, 4);
+        }
+        fname.Append('_');
+        fname.Append((char*)XRE_ChildProcessTypeToString(XRE_GetProcessType()));
+        fname.AppendLiteral("_pid");
+        fname.AppendInt((uint32_t)getpid());
+        if (hasLogExtension) {
+          fname.AppendLiteral(".log");
+        }
+      }
+      stream = ::fopen(fname.get(), "w" FOPEN_NO_INHERIT);
+      if (stream) {
+        MozillaRegisterDebugFD(fileno(stream));
+        *aResult = stream;
+        fprintf(stdout, "### %s defined -- logging %s to %s\n",
+                aEnvVar, aMsg, fname.get());
+      } else {
+        fprintf(stdout, "### %s defined -- unable to log %s to %s\n",
+                aEnvVar, aMsg, fname.get());
+        MOZ_ASSERT(false, "Tried and failed to create an XPCOM log");
+      }
+      return stream != nullptr;
+    }
+  }
+  return false;
+}
+
+
+static void
+maybeUnregisterAndCloseFile(FILE*& aFile)
+{
+  if (!aFile) {
+    return;
+  }
+
+  MozillaUnRegisterDebugFILE(aFile);
+  fclose(aFile);
+  aFile = nullptr;
+}
+
+
+static void
+InitTraceLog()
+{
+  if (gInitialized) {
+    return;
+  }
+  gInitialized = true;
+
+  bool defined = InitLog("XPCOM_MEM_BLOAT_LOG", "bloat/leaks", &gBloatLog);
+  if (!defined) {
+    gLogLeaksOnly = InitLog("XPCOM_MEM_LEAK_LOG", "leaks", &gBloatLog);
+  }
+  if (defined || gLogLeaksOnly) {
+    RecreateBloatView();
+    if (!gBloatView) {
+      NS_WARNING("out of memory");
+      maybeUnregisterAndCloseFile(gBloatLog);
+      gLogLeaksOnly = false;
+    }
+  }
+
+  InitLog("XPCOM_MEM_REFCNT_LOG", "refcounts", &gRefcntsLog);
+
+  InitLog("XPCOM_MEM_ALLOC_LOG", "new/delete", &gAllocLog);
+
+  const char* classes = getenv("XPCOM_MEM_LOG_CLASSES");
+
+#ifdef HAVE_CPP_DYNAMIC_CAST_TO_VOID_PTR
+  if (classes) {
+    InitLog("XPCOM_MEM_COMPTR_LOG", "nsCOMPtr", &gCOMPtrLog);
+  } else {
+    if (getenv("XPCOM_MEM_COMPTR_LOG")) {
+      fprintf(stdout, "### XPCOM_MEM_COMPTR_LOG defined -- but XPCOM_MEM_LOG_CLASSES is not defined\n");
+    }
+  }
+#else
+  const char* comptr_log = getenv("XPCOM_MEM_COMPTR_LOG");
+  if (comptr_log) {
+    fprintf(stdout, "### XPCOM_MEM_COMPTR_LOG defined -- but it will not work without dynamic_cast\n");
+  }
+#endif // HAVE_CPP_DYNAMIC_CAST_TO_VOID_PTR
+
+  if (classes) {
+    // if XPCOM_MEM_LOG_CLASSES was set to some value, the value is interpreted
+    // as a list of class names to track
+    gTypesToLog = PL_NewHashTable(256,
+                                  PL_HashString,
+                                  PL_CompareStrings,
+                                  PL_CompareValues,
+                                  &typesToLogHashAllocOps, nullptr);
+    if (!gTypesToLog) {
+      NS_WARNING("out of memory");
+      fprintf(stdout, "### XPCOM_MEM_LOG_CLASSES defined -- unable to log specific classes\n");
+    } else {
+      fprintf(stdout, "### XPCOM_MEM_LOG_CLASSES defined -- only logging these classes: ");
+      const char* cp = classes;
+      for (;;) {
+        char* cm = (char*)strchr(cp, ',');
+        if (cm) {
+          *cm = '\0';
+        }
+        PL_HashTableAdd(gTypesToLog, strdup(cp), (void*)1);
+        fprintf(stdout, "%s ", cp);
+        if (!cm) {
+          break;
+        }
+        *cm = ',';
+        cp = cm + 1;
+      }
+      fprintf(stdout, "\n");
+    }
+
+    gSerialNumbers = PL_NewHashTable(256,
+                                     HashNumber,
+                                     PL_CompareValues,
+                                     PL_CompareValues,
+                                     &serialNumberHashAllocOps, nullptr);
+
+
+  }
+
+  const char* objects = getenv("XPCOM_MEM_LOG_OBJECTS");
+  if (objects) {
+    gObjectsToLog = PL_NewHashTable(256,
+                                    HashNumber,
+                                    PL_CompareValues,
+                                    PL_CompareValues,
+                                    nullptr, nullptr);
+
+    if (!gObjectsToLog) {
+      NS_WARNING("out of memory");
+      fprintf(stdout, "### XPCOM_MEM_LOG_OBJECTS defined -- unable to log specific objects\n");
+    } else if (!(gRefcntsLog || gAllocLog || gCOMPtrLog)) {
+      fprintf(stdout, "### XPCOM_MEM_LOG_OBJECTS defined -- but none of XPCOM_MEM_(REFCNT|ALLOC|COMPTR)_LOG is defined\n");
+    } else {
+      fprintf(stdout, "### XPCOM_MEM_LOG_OBJECTS defined -- only logging these objects: ");
+      const char* cp = objects;
+      for (;;) {
+        char* cm = (char*)strchr(cp, ',');
+        if (cm) {
+          *cm = '\0';
+        }
+        intptr_t top = 0;
+        intptr_t bottom = 0;
+        while (*cp) {
+          if (*cp == '-') {
+            bottom = top;
+            top = 0;
+            ++cp;
+          }
+          top *= 10;
+          top += *cp - '0';
+          ++cp;
+        }
+        if (!bottom) {
+          bottom = top;
+        }
+        for (intptr_t serialno = bottom; serialno <= top; serialno++) {
+          PL_HashTableAdd(gObjectsToLog, (const void*)serialno, (void*)1);
+          fprintf(stdout, "%" PRIdPTR " ", serialno);
+        }
+        if (!cm) {
+          break;
+        }
+        *cm = ',';
+        cp = cm + 1;
+      }
+      fprintf(stdout, "\n");
+    }
+  }
+
+
+  if (gBloatLog) {
+    gLogging = OnlyBloatLogging;
+  }
+
+  if (gRefcntsLog || gAllocLog || gCOMPtrLog) {
+    gLogging = FullLogging;
+  }
+}
+
+
+extern "C" {
+
+static void
+PrintStackFrame(uint32_t aFrameNumber, void* aPC, void* aSP, void* aClosure)
+{
+  FILE* stream = (FILE*)aClosure;
+  MozCodeAddressDetails details;
+  char buf[1024];
+
+  MozDescribeCodeAddress(aPC, &details);
+  MozFormatCodeAddressDetails(buf, sizeof(buf), aFrameNumber, aPC, &details);
+  fprintf(stream, "%s\n", buf);
+  fflush(stream);
+}
+
+static void
+PrintStackFrameCached(uint32_t aFrameNumber, void* aPC, void* aSP,
+                      void* aClosure)
+{
+  auto stream = static_cast<FILE*>(aClosure);
+  static const size_t buflen = 1024;
+  char buf[buflen];
+  gCodeAddressService->GetLocation(aFrameNumber, aPC, buf, buflen);
+  fprintf(stream, "    %s\n", buf);
+  fflush(stream);
+}
+
+static void
+RecordStackFrame(uint32_t /*aFrameNumber*/, void* aPC, void* /*aSP*/,
+                 void* aClosure)
+{
+  auto locations = static_cast<std::vector<void*>*>(aClosure);
+  locations->push_back(aPC);
+}
+
+}
+
+void
+nsTraceRefcnt::WalkTheStack(FILE* aStream)
+{
+  MozStackWalk(PrintStackFrame, /* skipFrames */ 2, /* maxFrames */ 0, aStream,
+               0, nullptr);
+}
+
+/**
+ * This is a variant of |WalkTheStack| that uses |CodeAddressService| to cache
+ * the results of |NS_DescribeCodeAddress|. If |WalkTheStackCached| is being
+ * called frequently, it will be a few orders of magnitude faster than
+ * |WalkTheStack|. However, the cache uses a lot of memory, which can cause
+ * OOM crashes. Therefore, this should only be used for things like refcount
+ * logging which walk the stack extremely frequently.
+ */
+static void
+WalkTheStackCached(FILE* aStream)
+{
+  if (!gCodeAddressService) {
+    gCodeAddressService = new WalkTheStackCodeAddressService();
+  }
+  MozStackWalk(PrintStackFrameCached, /* skipFrames */ 2, /* maxFrames */ 0,
+               aStream, 0, nullptr);
+}
+
+static void
+WalkTheStackSavingLocations(std::vector<void*>& aLocations)
+{
+  if (!gCodeAddressService) {
+    gCodeAddressService = new WalkTheStackCodeAddressService();
+  }
+  static const int kFramesToSkip =
+    0 +                         // this frame gets inlined
+    1 +                         // GetSerialNumber
+    1;                          // NS_LogCtor
+  MozStackWalk(RecordStackFrame, kFramesToSkip, /* maxFrames */ 0,
+               &aLocations, 0, nullptr);
+}
+
+//----------------------------------------------------------------------
+
+EXPORT_XPCOM_API(void)
+NS_LogInit()
+{
+  NS_SetMainThread();
+
+  // FIXME: This is called multiple times, we should probably not allow that.
+  StackWalkInitCriticalAddress();
+  if (++gInitCount) {
+    nsTraceRefcnt::SetActivityIsLegal(true);
+  }
+}
+
+EXPORT_XPCOM_API(void)
+NS_LogTerm()
+{
+  mozilla::LogTerm();
+}
+
+#ifdef MOZ_DMD
+// If MOZ_DMD_SHUTDOWN_LOG is set, dump a DMD report to a file.
+// The value of this environment variable is used as the prefix
+// of the file name, so you probably want something like "/tmp/".
+// By default, this is run in all processes, but you can record a
+// log only for a specific process type by setting MOZ_DMD_LOG_PROCESS
+// to the process type you want to log, such as "default" or "tab".
+// This method can't use the higher level XPCOM file utilities
+// because it is run very late in shutdown to avoid recording
+// information about refcount logging entries.
+static void
+LogDMDFile()
+{
+  const char* dmdFilePrefix = PR_GetEnv("MOZ_DMD_SHUTDOWN_LOG");
+  if (!dmdFilePrefix) {
+    return;
+  }
+
+  const char* logProcessEnv = PR_GetEnv("MOZ_DMD_LOG_PROCESS");
+  if (logProcessEnv && !!strcmp(logProcessEnv, XRE_ChildProcessTypeToString(XRE_GetProcessType()))) {
+    return;
+  }
+
+  nsPrintfCString fileName("%sdmd-%d.log.gz", dmdFilePrefix, base::GetCurrentProcId());
+  FILE* logFile = fopen(fileName.get(), "w");
+  if (NS_WARN_IF(!logFile)) {
+    return;
+  }
+
+  nsMemoryInfoDumper::DumpDMDToFile(logFile);
+}
+#endif // MOZ_DMD
+
+namespace mozilla {
+void
+LogTerm()
+{
+  NS_ASSERTION(gInitCount > 0,
+               "NS_LogTerm without matching NS_LogInit");
+
+  if (--gInitCount == 0) {
+#ifdef DEBUG
+    /* FIXME bug 491977: This is only going to operate on the
+     * BlockingResourceBase which is compiled into
+     * libxul/libxpcom_core.so. Anyone using external linkage will
+     * have their own copy of BlockingResourceBase statics which will
+     * not be freed by this method.
+     *
+     * It sounds like what we really want is to be able to register a
+     * callback function to call at XPCOM shutdown.  Note that with
+     * this solution, however, we need to guarantee that
+     * BlockingResourceBase::Shutdown() runs after all other shutdown
+     * functions.
+     */
+    BlockingResourceBase::Shutdown();
+#endif
+
+    if (gInitialized) {
+      nsTraceRefcnt::DumpStatistics();
+      nsTraceRefcnt::ResetStatistics();
+    }
+    nsTraceRefcnt::Shutdown();
+    nsTraceRefcnt::SetActivityIsLegal(false);
+    gActivityTLS = BAD_TLS_INDEX;
+
+#ifdef MOZ_DMD
+    LogDMDFile();
+#endif
+  }
+}
+
+} // namespace mozilla
+
+EXPORT_XPCOM_API(void)
+NS_LogAddRef(void* aPtr, nsrefcnt aRefcnt,
+             const char* aClass, uint32_t aClassSize)
+{
+  ASSERT_ACTIVITY_IS_LEGAL;
+  if (!gInitialized) {
+    InitTraceLog();
+  }
+  if (gLogging == NoLogging) {
+    return;
+  }
+  if (aRefcnt == 1 || gLogging == FullLogging) {
+    AutoTraceLogLock lock;
+
+    if (aRefcnt == 1 && gBloatLog) {
+      BloatEntry* entry = GetBloatEntry(aClass, aClassSize);
+      if (entry) {
+        entry->Ctor();
+      }
+    }
+
+    // Here's the case where MOZ_COUNT_CTOR was not used,
+    // yet we still want to see creation information:
+
+    bool loggingThisType = (!gTypesToLog || LogThisType(aClass));
+    intptr_t serialno = 0;
+    if (gSerialNumbers && loggingThisType) {
+      serialno = GetSerialNumber(aPtr, aRefcnt == 1);
+      MOZ_ASSERT(serialno != 0,
+                 "Serial number requested for unrecognized pointer!  "
+                 "Are you memmoving a refcounted object?");
+      int32_t* count = GetRefCount(aPtr);
+      if (count) {
+        (*count)++;
+      }
+
+    }
+
+    bool loggingThisObject = (!gObjectsToLog || LogThisObj(serialno));
+    if (aRefcnt == 1 && gAllocLog && loggingThisType && loggingThisObject) {
+      fprintf(gAllocLog, "\n<%s> %p %" PRIdPTR " Create [thread %p]\n", aClass, aPtr, serialno, PR_GetCurrentThread());
+      WalkTheStackCached(gAllocLog);
+    }
+
+    if (gRefcntsLog && loggingThisType && loggingThisObject) {
+      // Can't use MOZ_LOG(), b/c it truncates the line
+      fprintf(gRefcntsLog, "\n<%s> %p %" PRIuPTR " AddRef %" PRIuPTR " [thread %p]\n",
+              aClass, aPtr, serialno, aRefcnt, PR_GetCurrentThread());
+      WalkTheStackCached(gRefcntsLog);
+      fflush(gRefcntsLog);
+    }
+  }
+}
+
+EXPORT_XPCOM_API(void)
+NS_LogRelease(void* aPtr, nsrefcnt aRefcnt, const char* aClass)
+{
+  ASSERT_ACTIVITY_IS_LEGAL;
+  if (!gInitialized) {
+    InitTraceLog();
+  }
+  if (gLogging == NoLogging) {
+    return;
+  }
+  if (aRefcnt == 0 || gLogging == FullLogging) {
+    AutoTraceLogLock lock;
+
+    if (aRefcnt == 0 && gBloatLog) {
+      BloatEntry* entry = GetBloatEntry(aClass, 0);
+      if (entry) {
+        entry->Dtor();
+      }
+    }
+
+    bool loggingThisType = (!gTypesToLog || LogThisType(aClass));
+    intptr_t serialno = 0;
+    if (gSerialNumbers && loggingThisType) {
+      serialno = GetSerialNumber(aPtr, false);
+      MOZ_ASSERT(serialno != 0,
+                 "Serial number requested for unrecognized pointer!  "
+                 "Are you memmoving a refcounted object?");
+      int32_t* count = GetRefCount(aPtr);
+      if (count) {
+        (*count)--;
+      }
+
+    }
+
+    bool loggingThisObject = (!gObjectsToLog || LogThisObj(serialno));
+    if (gRefcntsLog && loggingThisType && loggingThisObject) {
+      // Can't use MOZ_LOG(), b/c it truncates the line
+      fprintf(gRefcntsLog,
+              "\n<%s> %p %" PRIuPTR " Release %" PRIuPTR " [thread %p]\n",
+              aClass, aPtr, serialno, aRefcnt, PR_GetCurrentThread());
+      WalkTheStackCached(gRefcntsLog);
+      fflush(gRefcntsLog);
+    }
+
+    // Here's the case where MOZ_COUNT_DTOR was not used,
+    // yet we still want to see deletion information:
+
+    if (aRefcnt == 0 && gAllocLog && loggingThisType && loggingThisObject) {
+      fprintf(gAllocLog, "\n<%s> %p %" PRIdPTR " Destroy [thread %p]\n", aClass, aPtr, serialno, PR_GetCurrentThread());
+      WalkTheStackCached(gAllocLog);
+    }
+
+    if (aRefcnt == 0 && gSerialNumbers && loggingThisType) {
+      RecycleSerialNumberPtr(aPtr);
+    }
+  }
+}
+
+EXPORT_XPCOM_API(void)
+NS_LogCtor(void* aPtr, const char* aType, uint32_t aInstanceSize)
+{
+  ASSERT_ACTIVITY_IS_LEGAL;
+  if (!gInitialized) {
+    InitTraceLog();
+  }
+
+  if (gLogging == NoLogging) {
+    return;
+  }
+
+  AutoTraceLogLock lock;
+
+  if (gBloatLog) {
+    BloatEntry* entry = GetBloatEntry(aType, aInstanceSize);
+    if (entry) {
+      entry->Ctor();
+    }
+  }
+
+  bool loggingThisType = (!gTypesToLog || LogThisType(aType));
+  intptr_t serialno = 0;
+  if (gSerialNumbers && loggingThisType) {
+    serialno = GetSerialNumber(aPtr, true);
+    MOZ_ASSERT(serialno != 0, "GetSerialNumber should never return 0 when passed true");
+  }
+
+  bool loggingThisObject = (!gObjectsToLog || LogThisObj(serialno));
+  if (gAllocLog && loggingThisType && loggingThisObject) {
+    fprintf(gAllocLog, "\n<%s> %p %" PRIdPTR " Ctor (%d)\n",
+            aType, aPtr, serialno, aInstanceSize);
+    WalkTheStackCached(gAllocLog);
+  }
+}
+
+
+EXPORT_XPCOM_API(void)
+NS_LogDtor(void* aPtr, const char* aType, uint32_t aInstanceSize)
+{
+  ASSERT_ACTIVITY_IS_LEGAL;
+  if (!gInitialized) {
+    InitTraceLog();
+  }
+
+  if (gLogging == NoLogging) {
+    return;
+  }
+
+  AutoTraceLogLock lock;
+
+  if (gBloatLog) {
+    BloatEntry* entry = GetBloatEntry(aType, aInstanceSize);
+    if (entry) {
+      entry->Dtor();
+    }
+  }
+
+  bool loggingThisType = (!gTypesToLog || LogThisType(aType));
+  intptr_t serialno = 0;
+  if (gSerialNumbers && loggingThisType) {
+    serialno = GetSerialNumber(aPtr, false);
+    MOZ_ASSERT(serialno != 0,
+               "Serial number requested for unrecognized pointer!  "
+               "Are you memmoving a MOZ_COUNT_CTOR-tracked object?");
+    RecycleSerialNumberPtr(aPtr);
+  }
+
+  bool loggingThisObject = (!gObjectsToLog || LogThisObj(serialno));
+
+  // (If we're on a losing architecture, don't do this because we'll be
+  // using LogDeleteXPCOM instead to get file and line numbers.)
+  if (gAllocLog && loggingThisType && loggingThisObject) {
+    fprintf(gAllocLog, "\n<%s> %p %" PRIdPTR " Dtor (%d)\n",
+            aType, aPtr, serialno, aInstanceSize);
+    WalkTheStackCached(gAllocLog);
+  }
+}
+
+
+EXPORT_XPCOM_API(void)
+NS_LogCOMPtrAddRef(void* aCOMPtr, nsISupports* aObject)
+{
+#ifdef HAVE_CPP_DYNAMIC_CAST_TO_VOID_PTR
+  // Get the most-derived object.
+  void* object = dynamic_cast<void*>(aObject);
+
+  // This is a very indirect way of finding out what the class is
+  // of the object being logged.  If we're logging a specific type,
+  // then
+  if (!gTypesToLog || !gSerialNumbers) {
+    return;
+  }
+  if (!gInitialized) {
+    InitTraceLog();
+  }
+  if (gLogging == FullLogging) {
+    AutoTraceLogLock lock;
+
+    intptr_t serialno = GetSerialNumber(object, false);
+    if (serialno == 0) {
+      return;
+    }
+
+    int32_t* count = GetCOMPtrCount(object);
+    if (count) {
+      (*count)++;
+    }
+
+    bool loggingThisObject = (!gObjectsToLog || LogThisObj(serialno));
+
+    if (gCOMPtrLog && loggingThisObject) {
+      fprintf(gCOMPtrLog, "\n<?> %p %" PRIdPTR " nsCOMPtrAddRef %d %p\n",
+              object, serialno, count ? (*count) : -1, aCOMPtr);
+      WalkTheStackCached(gCOMPtrLog);
+    }
+  }
+#endif // HAVE_CPP_DYNAMIC_CAST_TO_VOID_PTR
+}
+
+
+EXPORT_XPCOM_API(void)
+NS_LogCOMPtrRelease(void* aCOMPtr, nsISupports* aObject)
+{
+#ifdef HAVE_CPP_DYNAMIC_CAST_TO_VOID_PTR
+  // Get the most-derived object.
+  void* object = dynamic_cast<void*>(aObject);
+
+  // This is a very indirect way of finding out what the class is
+  // of the object being logged.  If we're logging a specific type,
+  // then
+  if (!gTypesToLog || !gSerialNumbers) {
+    return;
+  }
+  if (!gInitialized) {
+    InitTraceLog();
+  }
+  if (gLogging == FullLogging) {
+    AutoTraceLogLock lock;
+
+    intptr_t serialno = GetSerialNumber(object, false);
+    if (serialno == 0) {
+      return;
+    }
+
+    int32_t* count = GetCOMPtrCount(object);
+    if (count) {
+      (*count)--;
+    }
+
+    bool loggingThisObject = (!gObjectsToLog || LogThisObj(serialno));
+
+    if (gCOMPtrLog && loggingThisObject) {
+      fprintf(gCOMPtrLog, "\n<?> %p %" PRIdPTR " nsCOMPtrRelease %d %p\n",
+              object, serialno, count ? (*count) : -1, aCOMPtr);
+      WalkTheStackCached(gCOMPtrLog);
+    }
+  }
+#endif // HAVE_CPP_DYNAMIC_CAST_TO_VOID_PTR
+}
+
+void
+nsTraceRefcnt::Shutdown()
+{
+  gCodeAddressService = nullptr;
+  if (gBloatView) {
+    PL_HashTableDestroy(gBloatView);
+    gBloatView = nullptr;
+  }
+  if (gTypesToLog) {
+    PL_HashTableDestroy(gTypesToLog);
+    gTypesToLog = nullptr;
+  }
+  if (gObjectsToLog) {
+    PL_HashTableDestroy(gObjectsToLog);
+    gObjectsToLog = nullptr;
+  }
+  if (gSerialNumbers) {
+    PL_HashTableDestroy(gSerialNumbers);
+    gSerialNumbers = nullptr;
+  }
+  maybeUnregisterAndCloseFile(gBloatLog);
+  maybeUnregisterAndCloseFile(gRefcntsLog);
+  maybeUnregisterAndCloseFile(gAllocLog);
+  maybeUnregisterAndCloseFile(gCOMPtrLog);
+}
+
+void
+nsTraceRefcnt::SetActivityIsLegal(bool aLegal)
+{
+  if (gActivityTLS == BAD_TLS_INDEX) {
+    PR_NewThreadPrivateIndex(&gActivityTLS, nullptr);
+  }
+
+  PR_SetThreadPrivate(gActivityTLS, reinterpret_cast<void*>(!aLegal));
+}
diff --git a/xpcom/base/nsTraceRefcnt.h b/xpcom/base/nsTraceRefcnt.h
new file mode 100644
index 000000000..73e123a3f
--- /dev/null
+++ b/xpcom/base/nsTraceRefcnt.h
@@ -0,0 +1,40 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef nsTraceRefcnt_h___
+#define nsTraceRefcnt_h___
+
+#include <stdio.h> // for FILE
+#include "nscore.h"
+
+class nsTraceRefcnt
+{
+public:
+  static void Shutdown();
+
+  static nsresult DumpStatistics();
+
+  static void ResetStatistics();
+
+  static void WalkTheStack(FILE* aStream);
+
+  /**
+   * Tell nsTraceRefcnt whether refcounting, allocation, and destruction
+   * activity is legal.  This is used to trigger assertions for any such
+   * activity that occurs because of static constructors or destructors.
+   */
+  static void SetActivityIsLegal(bool aLegal);
+};
+
+////////////////////////////////////////////////////////////////////////////////
+// And now for that utility that you've all been asking for...
+
+extern "C" void
+NS_MeanAndStdDev(double aNumberOfValues,
+                 double aSumOfValues, double aSumOfSquaredValues,
+                 double* aMeanResult, double* aStdDevResult);
+
+////////////////////////////////////////////////////////////////////////////////
+#endif
diff --git a/xpcom/base/nsUUIDGenerator.cpp b/xpcom/base/nsUUIDGenerator.cpp
new file mode 100644
index 000000000..254a01322
--- /dev/null
+++ b/xpcom/base/nsUUIDGenerator.cpp
@@ -0,0 +1,177 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#if defined(XP_WIN)
+#include <windows.h>
+#include <objbase.h>
+#elif defined(XP_MACOSX)
+#include <CoreFoundation/CoreFoundation.h>
+#else
+#include <stdlib.h>
+#include "prrng.h"
+#endif
+
+#include "nsUUIDGenerator.h"
+
+#ifdef ANDROID
+extern "C" NS_EXPORT void arc4random_buf(void*, size_t);
+#endif
+
+using namespace mozilla;
+
+NS_IMPL_ISUPPORTS(nsUUIDGenerator, nsIUUIDGenerator)
+
+nsUUIDGenerator::nsUUIDGenerator()
+  : mLock("nsUUIDGenerator.mLock")
+{
+}
+
+nsUUIDGenerator::~nsUUIDGenerator()
+{
+}
+
+nsresult
+nsUUIDGenerator::Init()
+{
+  // We're a service, so we're guaranteed that Init() is not going
+  // to be reentered while we're inside Init().
+
+#if !defined(XP_WIN) && !defined(XP_MACOSX) && !defined(HAVE_ARC4RANDOM)
+  /* initialize random number generator using NSPR random noise */
+  unsigned int seed;
+
+  size_t bytes = 0;
+  while (bytes < sizeof(seed)) {
+    size_t nbytes = PR_GetRandomNoise(((unsigned char*)&seed) + bytes,
+                                      sizeof(seed) - bytes);
+    if (nbytes == 0) {
+      return NS_ERROR_FAILURE;
+    }
+    bytes += nbytes;
+  }
+
+  /* Initialize a new RNG state, and immediately switch
+   * back to the previous one -- we want to use mState
+   * only for our own calls to random().
+   */
+  mSavedState = initstate(seed, mState, sizeof(mState));
+  setstate(mSavedState);
+
+  mRBytes = 4;
+#ifdef RAND_MAX
+  if ((unsigned long)RAND_MAX < 0xffffffffUL) {
+    mRBytes = 3;
+  }
+  if ((unsigned long)RAND_MAX < 0x00ffffffUL) {
+    mRBytes = 2;
+  }
+  if ((unsigned long)RAND_MAX < 0x0000ffffUL) {
+    mRBytes = 1;
+  }
+  if ((unsigned long)RAND_MAX < 0x000000ffUL) {
+    return NS_ERROR_FAILURE;
+  }
+#endif
+
+#endif /* non XP_WIN and non XP_MACOSX and non ARC4RANDOM */
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsUUIDGenerator::GenerateUUID(nsID** aRet)
+{
+  nsID* id = static_cast<nsID*>(moz_xmalloc(sizeof(nsID)));
+  if (!id) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  nsresult rv = GenerateUUIDInPlace(id);
+  if (NS_FAILED(rv)) {
+    free(id);
+    return rv;
+  }
+
+  *aRet = id;
+  return rv;
+}
+
+NS_IMETHODIMP
+nsUUIDGenerator::GenerateUUIDInPlace(nsID* aId)
+{
+  // The various code in this method is probably not threadsafe, so lock
+  // across the whole method.
+  MutexAutoLock lock(mLock);
+
+#if defined(XP_WIN)
+  HRESULT hr = CoCreateGuid((GUID*)aId);
+  if (FAILED(hr)) {
+    return NS_ERROR_FAILURE;
+  }
+#elif defined(XP_MACOSX)
+  CFUUIDRef uuid = CFUUIDCreate(kCFAllocatorDefault);
+  if (!uuid) {
+    return NS_ERROR_FAILURE;
+  }
+
+  CFUUIDBytes bytes = CFUUIDGetUUIDBytes(uuid);
+  memcpy(aId, &bytes, sizeof(nsID));
+
+  CFRelease(uuid);
+#else /* not windows or OS X; generate randomness using random(). */
+  /* XXX we should be saving the return of setstate here and switching
+   * back to it; instead, we use the value returned when we called
+   * initstate, since older glibc's have broken setstate() return values
+   */
+#ifndef HAVE_ARC4RANDOM
+  setstate(mState);
+#endif
+
+#ifdef HAVE_ARC4RANDOM_BUF
+  arc4random_buf(aId, sizeof(nsID));
+#else /* HAVE_ARC4RANDOM_BUF */
+  size_t bytesLeft = sizeof(nsID);
+  while (bytesLeft > 0) {
+#ifdef HAVE_ARC4RANDOM
+    long rval = arc4random();
+    const size_t mRBytes = 4;
+#else
+    long rval = random();
+#endif
+
+
+    uint8_t* src = (uint8_t*)&rval;
+    // We want to grab the mRBytes least significant bytes of rval, since
+    // mRBytes less than sizeof(rval) means the high bytes are 0.
+#ifdef IS_BIG_ENDIAN
+    src += sizeof(rval) - mRBytes;
+#endif
+    uint8_t* dst = ((uint8_t*)aId) + (sizeof(nsID) - bytesLeft);
+    size_t toWrite = (bytesLeft < mRBytes ? bytesLeft : mRBytes);
+    for (size_t i = 0; i < toWrite; i++) {
+      dst[i] = src[i];
+    }
+
+    bytesLeft -= toWrite;
+  }
+#endif /* HAVE_ARC4RANDOM_BUF */
+
+  /* Put in the version */
+  aId->m2 &= 0x0fff;
+  aId->m2 |= 0x4000;
+
+  /* Put in the variant */
+  aId->m3[0] &= 0x3f;
+  aId->m3[0] |= 0x80;
+
+#ifndef HAVE_ARC4RANDOM
+  /* Restore the previous RNG state */
+  setstate(mSavedState);
+#endif
+#endif
+
+  return NS_OK;
+}
diff --git a/xpcom/base/nsUUIDGenerator.h b/xpcom/base/nsUUIDGenerator.h
new file mode 100644
index 000000000..dd86093f8
--- /dev/null
+++ b/xpcom/base/nsUUIDGenerator.h
@@ -0,0 +1,44 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef _NSUUIDGENERATOR_H_
+#define _NSUUIDGENERATOR_H_
+
+#include "mozilla/Attributes.h"
+#include "mozilla/Mutex.h"
+
+#include "nsIUUIDGenerator.h"
+
+class nsUUIDGenerator final : public nsIUUIDGenerator
+{
+public:
+  nsUUIDGenerator();
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  NS_DECL_NSIUUIDGENERATOR
+
+  nsresult Init();
+
+private:
+  ~nsUUIDGenerator();
+
+protected:
+
+  mozilla::Mutex mLock;
+#if !defined(XP_WIN) && !defined(XP_MACOSX) && !defined(HAVE_ARC4RANDOM)
+  char mState[128];
+  char* mSavedState;
+  uint8_t mRBytes;
+#endif
+};
+
+#define NS_UUID_GENERATOR_CONTRACTID "@mozilla.org/uuid-generator;1"
+#define NS_UUID_GENERATOR_CID \
+{ 0x706d36bb, 0xbf79, 0x4293, \
+{ 0x81, 0xf2, 0x8f, 0x68, 0x28, 0xc1, 0x8f, 0x9d } }
+
+#endif /* _NSUUIDGENERATOR_H_ */
diff --git a/xpcom/base/nsVersionComparatorImpl.cpp b/xpcom/base/nsVersionComparatorImpl.cpp
new file mode 100644
index 000000000..8a37d8b1a
--- /dev/null
+++ b/xpcom/base/nsVersionComparatorImpl.cpp
@@ -0,0 +1,22 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsVersionComparatorImpl.h"
+#include "nsVersionComparator.h"
+#include "nsString.h"
+
+NS_IMPL_ISUPPORTS(nsVersionComparatorImpl, nsIVersionComparator)
+
+NS_IMETHODIMP
+nsVersionComparatorImpl::Compare(const nsACString& aStr1,
+                                 const nsACString& aStr2,
+                                 int32_t* aResult)
+{
+  *aResult = mozilla::CompareVersions(PromiseFlatCString(aStr1).get(),
+                                      PromiseFlatCString(aStr2).get());
+
+  return NS_OK;
+}
diff --git a/xpcom/base/nsVersionComparatorImpl.h b/xpcom/base/nsVersionComparatorImpl.h
new file mode 100644
index 000000000..84a76d1bb
--- /dev/null
+++ b/xpcom/base/nsVersionComparatorImpl.h
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Attributes.h"
+
+#include "nsIVersionComparator.h"
+
+class nsVersionComparatorImpl final : public nsIVersionComparator
+{
+  ~nsVersionComparatorImpl() {}
+
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIVERSIONCOMPARATOR
+};
+
+#define NS_VERSIONCOMPARATOR_CONTRACTID "@mozilla.org/xpcom/version-comparator;1"
+
+// c6e47036-ca94-4be3-963a-9abd8705f7a8
+#define NS_VERSIONCOMPARATOR_CID \
+{ 0xc6e47036, 0xca94, 0x4be3, \
+  { 0x96, 0x3a, 0x9a, 0xbd, 0x87, 0x05, 0xf7, 0xa8 } }
diff --git a/xpcom/base/nsWeakPtr.h b/xpcom/base/nsWeakPtr.h
new file mode 100644
index 000000000..e2f7c37f1
--- /dev/null
+++ b/xpcom/base/nsWeakPtr.h
@@ -0,0 +1,15 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsWeakPtr_h__
+#define nsWeakPtr_h__
+
+#include "nsIWeakReference.h"
+#include "nsCOMPtr.h"
+
+// typedef nsCOMPtr<nsIWeakReference> nsWeakPtr;
+
+#endif
diff --git a/xpcom/base/nsWindowsHelpers.h b/xpcom/base/nsWindowsHelpers.h
new file mode 100644
index 000000000..66505b345
--- /dev/null
+++ b/xpcom/base/nsWindowsHelpers.h
@@ -0,0 +1,371 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsWindowsHelpers_h
+#define nsWindowsHelpers_h
+
+#include <windows.h>
+#include "nsAutoRef.h"
+#include "nscore.h"
+#include "mozilla/Assertions.h"
+
+// ----------------------------------------------------------------------------
+// Critical Section helper class
+// ----------------------------------------------------------------------------
+
+class AutoCriticalSection
+{
+public:
+  AutoCriticalSection(LPCRITICAL_SECTION aSection)
+    : mSection(aSection)
+  {
+    ::EnterCriticalSection(mSection);
+  }
+  ~AutoCriticalSection()
+  {
+    ::LeaveCriticalSection(mSection);
+  }
+private:
+  LPCRITICAL_SECTION mSection;
+};
+
+template<>
+class nsAutoRefTraits<HKEY>
+{
+public:
+  typedef HKEY RawRef;
+  static HKEY Void()
+  {
+    return nullptr;
+  }
+
+  static void Release(RawRef aFD)
+  {
+    if (aFD != Void()) {
+      RegCloseKey(aFD);
+    }
+  }
+};
+
+template<>
+class nsAutoRefTraits<HDC>
+{
+public:
+  typedef HDC RawRef;
+  static HDC Void()
+  {
+    return nullptr;
+  }
+
+  static void Release(RawRef aFD)
+  {
+    if (aFD != Void()) {
+      ::DeleteDC(aFD);
+    }
+  }
+};
+
+template<>
+class nsAutoRefTraits<HBRUSH>
+{
+public:
+  typedef HBRUSH RawRef;
+  static HBRUSH Void()
+  {
+    return nullptr;
+  }
+
+  static void Release(RawRef aFD)
+  {
+    if (aFD != Void()) {
+      ::DeleteObject(aFD);
+    }
+  }
+};
+
+template<>
+class nsAutoRefTraits<HRGN>
+{
+public:
+  typedef HRGN RawRef;
+  static HRGN Void()
+  {
+    return nullptr;
+  }
+
+  static void Release(RawRef aFD)
+  {
+    if (aFD != Void()) {
+      ::DeleteObject(aFD);
+    }
+  }
+};
+
+template<>
+class nsAutoRefTraits<HBITMAP>
+{
+public:
+  typedef HBITMAP RawRef;
+  static HBITMAP Void()
+  {
+    return nullptr;
+  }
+
+  static void Release(RawRef aFD)
+  {
+    if (aFD != Void()) {
+      ::DeleteObject(aFD);
+    }
+  }
+};
+
+template<>
+class nsAutoRefTraits<SC_HANDLE>
+{
+public:
+  typedef SC_HANDLE RawRef;
+  static SC_HANDLE Void()
+  {
+    return nullptr;
+  }
+
+  static void Release(RawRef aFD)
+  {
+    if (aFD != Void()) {
+      CloseServiceHandle(aFD);
+    }
+  }
+};
+
+template<>
+class nsSimpleRef<HANDLE>
+{
+protected:
+  typedef HANDLE RawRef;
+
+  nsSimpleRef() : mRawRef(nullptr)
+  {
+  }
+
+  nsSimpleRef(RawRef aRawRef) : mRawRef(aRawRef)
+  {
+  }
+
+  bool HaveResource() const
+  {
+    return mRawRef && mRawRef != INVALID_HANDLE_VALUE;
+  }
+
+public:
+  RawRef get() const
+  {
+    return mRawRef;
+  }
+
+  static void Release(RawRef aRawRef)
+  {
+    if (aRawRef && aRawRef != INVALID_HANDLE_VALUE) {
+      CloseHandle(aRawRef);
+    }
+  }
+  RawRef mRawRef;
+};
+
+
+template<>
+class nsAutoRefTraits<HMODULE>
+{
+public:
+  typedef HMODULE RawRef;
+  static RawRef Void()
+  {
+    return nullptr;
+  }
+
+  static void Release(RawRef aFD)
+  {
+    if (aFD != Void()) {
+      FreeLibrary(aFD);
+    }
+  }
+};
+
+
+template<>
+class nsAutoRefTraits<DEVMODEW*>
+{
+public:
+  typedef DEVMODEW* RawRef;
+  static RawRef Void()
+  {
+    return nullptr;
+  }
+
+  static void Release(RawRef aDevMode)
+  {
+    if (aDevMode != Void()) {
+      ::HeapFree(::GetProcessHeap(), 0, aDevMode);
+    }
+  }
+};
+
+
+// HGLOBAL is just a typedef of HANDLE which nsSimpleRef has a specialization of,
+// that means having a nsAutoRefTraits specialization for HGLOBAL is useless.
+// Therefore we create a wrapper class for HGLOBAL to make nsAutoRefTraits and
+// nsAutoRef work as intention.
+class nsHGLOBAL {
+public:
+  nsHGLOBAL(HGLOBAL hGlobal) : m_hGlobal(hGlobal)
+  {
+  }
+
+  operator HGLOBAL() const
+  {
+    return m_hGlobal;
+  }
+
+private:
+  HGLOBAL m_hGlobal;
+};
+
+
+template<>
+class nsAutoRefTraits<nsHGLOBAL>
+{
+public:
+  typedef nsHGLOBAL RawRef;
+  static RawRef Void()
+  {
+    return nullptr;
+  }
+
+  static void Release(RawRef hGlobal)
+  {
+    ::GlobalFree(hGlobal);
+  }
+};
+
+
+// Because Printer's HANDLE uses ClosePrinter and we already have nsAutoRef<HANDLE>
+// which uses CloseHandle so we need to create a wrapper class for HANDLE to have
+// another specialization for nsAutoRefTraits.
+class nsHPRINTER {
+public:
+  nsHPRINTER(HANDLE hPrinter) : m_hPrinter(hPrinter)
+  {
+  }
+
+  operator HANDLE() const
+  {
+    return m_hPrinter;
+  }
+
+  HANDLE* operator&()
+  {
+    return &m_hPrinter;
+  }
+
+private:
+  HANDLE m_hPrinter;
+};
+
+
+// winspool.h header has AddMonitor macro, it conflicts with AddMonitor member
+// function in TaskbarPreview.cpp and TaskbarTabPreview.cpp. Beside, we only
+// need ClosePrinter here for Release function, so having its prototype is enough.
+extern "C" BOOL WINAPI ClosePrinter(HANDLE hPrinter);
+
+
+template<>
+class nsAutoRefTraits<nsHPRINTER>
+{
+public:
+  typedef nsHPRINTER RawRef;
+  static RawRef Void()
+  {
+    return nullptr;
+  }
+
+  static void Release(RawRef hPrinter)
+  {
+    ::ClosePrinter(hPrinter);
+  }
+};
+
+
+typedef nsAutoRef<HKEY> nsAutoRegKey;
+typedef nsAutoRef<HDC> nsAutoHDC;
+typedef nsAutoRef<HBRUSH> nsAutoBrush;
+typedef nsAutoRef<HRGN> nsAutoRegion;
+typedef nsAutoRef<HBITMAP> nsAutoBitmap;
+typedef nsAutoRef<SC_HANDLE> nsAutoServiceHandle;
+typedef nsAutoRef<HANDLE> nsAutoHandle;
+typedef nsAutoRef<HMODULE> nsModuleHandle;
+typedef nsAutoRef<DEVMODEW*> nsAutoDevMode;
+typedef nsAutoRef<nsHGLOBAL> nsAutoGlobalMem;
+typedef nsAutoRef<nsHPRINTER> nsAutoPrinter;
+
+namespace {
+
+// Construct a path "<system32>\<aModule>". return false if the output buffer
+// is too small.
+// Note: If the system path cannot be found, or doesn't fit in the output buffer
+// with the module name, we will just ignore the system path and output the
+// module name alone;
+// this may mean using a normal search path wherever the output is used.
+bool inline
+ConstructSystem32Path(LPCWSTR aModule, WCHAR* aSystemPath, UINT aSize)
+{
+  MOZ_ASSERT(aSystemPath);
+
+  size_t fileLen = wcslen(aModule);
+  if (fileLen >= aSize) {
+    // The module name alone cannot even fit!
+    return false;
+  }
+
+  size_t systemDirLen = GetSystemDirectoryW(aSystemPath, aSize);
+
+  if (systemDirLen) {
+    if (systemDirLen < aSize - fileLen) {
+      // Make the system directory path terminate with a slash.
+      if (aSystemPath[systemDirLen - 1] != L'\\') {
+        if (systemDirLen + 1 < aSize - fileLen) {
+            aSystemPath[systemDirLen] = L'\\';
+            ++systemDirLen;
+            // No need to re-nullptr terminate.
+        } else {
+          // Couldn't fit the system path with added slash.
+          systemDirLen = 0;
+        }
+      }
+    } else {
+      // Couldn't fit the system path.
+      systemDirLen = 0;
+    }
+  }
+
+  MOZ_ASSERT(systemDirLen + fileLen < aSize);
+
+  wcsncpy(aSystemPath + systemDirLen, aModule, fileLen);
+  aSystemPath[systemDirLen + fileLen] = L'\0';
+  return true;
+}
+
+HMODULE inline
+LoadLibrarySystem32(LPCWSTR aModule)
+{
+  WCHAR systemPath[MAX_PATH + 1];
+  if (!ConstructSystem32Path(aModule, systemPath, MAX_PATH + 1)) {
+    return NULL;
+  }
+  return LoadLibraryW(systemPath);
+}
+
+}
+
+#endif
diff --git a/xpcom/base/nscore.h b/xpcom/base/nscore.h
new file mode 100644
index 000000000..f6e73c6bc
--- /dev/null
+++ b/xpcom/base/nscore.h
@@ -0,0 +1,288 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nscore_h___
+#define nscore_h___
+
+/**
+ * Make sure that we have the proper platform specific
+ * c++ definitions needed by nscore.h
+ */
+#ifndef _XPCOM_CONFIG_H_
+#include "xpcom-config.h"
+#endif
+
+/* Definitions of functions and operators that allocate memory. */
+#if !defined(XPCOM_GLUE) && !defined(NS_NO_XPCOM) && !defined(MOZ_NO_MOZALLOC)
+#  include "mozilla/mozalloc.h"
+#endif
+
+/**
+ * Incorporate the integer data types which XPCOM uses.
+ */
+#include <stddef.h>
+#include <stdint.h>
+
+#include "mozilla/RefCountType.h"
+
+/* Core XPCOM declarations. */
+
+/*----------------------------------------------------------------------*/
+/* Import/export defines */
+
+#ifdef HAVE_VISIBILITY_HIDDEN_ATTRIBUTE
+#define NS_VISIBILITY_HIDDEN   __attribute__ ((visibility ("hidden")))
+#else
+#define NS_VISIBILITY_HIDDEN
+#endif
+
+#if defined(HAVE_VISIBILITY_ATTRIBUTE)
+#define NS_VISIBILITY_DEFAULT __attribute__ ((visibility ("default")))
+#elif defined(__SUNPRO_C) || defined(__SUNPRO_CC)
+#define NS_VISIBILITY_DEFAULT __global
+#else
+#define NS_VISIBILITY_DEFAULT
+#endif
+
+#define NS_HIDDEN_(type)   NS_VISIBILITY_HIDDEN type
+#define NS_EXTERNAL_VIS_(type) NS_VISIBILITY_DEFAULT type
+
+#define NS_HIDDEN           NS_VISIBILITY_HIDDEN
+#define NS_EXTERNAL_VIS     NS_VISIBILITY_DEFAULT
+
+/**
+ * Mark a function as using a potentially non-standard function calling
+ * convention.  This can be used on functions that are called very
+ * frequently, to reduce the overhead of the function call.  It is still worth
+ * using the macro for C++ functions which take no parameters since it allows
+ * passing |this| in a register.
+ *
+ *  - Do not use this on any scriptable interface method since xptcall won't be
+ *    aware of the different calling convention.
+ *  - This must appear on the declaration, not the definition.
+ *  - Adding this to a public function _will_ break binary compatibility.
+ *  - This may be used on virtual functions but you must ensure it is applied
+ *    to all implementations - the compiler will _not_ warn but it will crash.
+ *  - This has no effect for functions which take a variable number of
+ *    arguments.
+ *  - __fastcall on windows should not be applied to class
+ *    constructors/destructors - use the NS_CONSTRUCTOR_FASTCALL macro for
+ *    constructors/destructors.
+ *
+ * Examples: int NS_FASTCALL func1(char *foo);
+ *           NS_HIDDEN_(int) NS_FASTCALL func2(char *foo);
+ */
+
+#if defined(__i386__) && defined(__GNUC__)
+#define NS_FASTCALL __attribute__ ((regparm (3), stdcall))
+#define NS_CONSTRUCTOR_FASTCALL __attribute__ ((regparm (3), stdcall))
+#elif defined(XP_WIN) && !defined(_WIN64)
+#define NS_FASTCALL __fastcall
+#define NS_CONSTRUCTOR_FASTCALL
+#else
+#define NS_FASTCALL
+#define NS_CONSTRUCTOR_FASTCALL
+#endif
+
+#ifdef XP_WIN
+
+#define NS_IMPORT __declspec(dllimport)
+#define NS_IMPORT_(type) __declspec(dllimport) type __stdcall
+#define NS_EXPORT __declspec(dllexport)
+#define NS_EXPORT_(type) __declspec(dllexport) type __stdcall
+#define NS_IMETHOD_(type) virtual type __stdcall
+#define NS_IMETHODIMP_(type) type __stdcall
+#define NS_METHOD_(type) type __stdcall
+#define NS_CALLBACK_(_type, _name) _type (__stdcall * _name)
+#ifndef _WIN64
+// Win64 has only one calling convention.  __stdcall will be ignored by the compiler.
+#define NS_STDCALL __stdcall
+#define NS_HAVE_STDCALL
+#else
+#define NS_STDCALL
+#endif
+#define NS_FROZENCALL __cdecl
+
+#else
+
+#define NS_IMPORT NS_EXTERNAL_VIS
+#define NS_IMPORT_(type) NS_EXTERNAL_VIS_(type)
+#define NS_EXPORT NS_EXTERNAL_VIS
+#define NS_EXPORT_(type) NS_EXTERNAL_VIS_(type)
+#define NS_IMETHOD_(type) virtual type
+#define NS_IMETHODIMP_(type) type
+#define NS_METHOD_(type) type
+#define NS_CALLBACK_(_type, _name) _type (* _name)
+#define NS_STDCALL
+#define NS_FROZENCALL
+
+#endif
+
+/**
+ * Macro for creating typedefs for pointer-to-member types which are
+ * declared with stdcall.  It is important to use this for any type which is
+ * declared as stdcall (i.e. NS_IMETHOD).  For example, instead of writing:
+ *
+ *  typedef nsresult (nsIFoo::*someType)(nsISupports* arg);
+ *
+ *  you should write:
+ *
+ *  typedef
+ *  NS_STDCALL_FUNCPROTO(nsresult, someType, nsIFoo, typeFunc, (nsISupports*));
+ *
+ *  where nsIFoo::typeFunc is any method declared as
+ *  NS_IMETHOD typeFunc(nsISupports*);
+ *
+ *  XXX this can be simplified to always use the non-typeof implementation
+ *  when http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11893 is fixed.
+ */
+
+#ifdef __GNUC__
+#define NS_STDCALL_FUNCPROTO(ret, name, class, func, args) \
+  typeof(&class::func) name
+#else
+#define NS_STDCALL_FUNCPROTO(ret, name, class, func, args) \
+  ret (NS_STDCALL class::*name) args
+#endif
+
+/**
+ * Deprecated declarations.
+ */
+#ifdef __GNUC__
+# define MOZ_DEPRECATED __attribute__((deprecated))
+#elif defined(_MSC_VER)
+# define MOZ_DEPRECATED __declspec(deprecated)
+#else
+# define MOZ_DEPRECATED
+#endif
+
+/**
+ * Generic API modifiers which return the standard XPCOM nsresult type
+ *
+ * - NS_IMETHOD: use for in-class declarations and definitions.
+ * - NS_IMETHODIMP: use for out-of-class definitions.
+ * - NS_METHOD: usually used in conjunction with NS_CALLBACK.
+ * - NS_CALLBACK: used in some legacy situations. Best avoided.
+ */
+#define NS_IMETHOD          NS_IMETHOD_(nsresult)
+#define NS_IMETHODIMP       NS_IMETHODIMP_(nsresult)
+#define NS_METHOD           NS_METHOD_(nsresult)
+#define NS_CALLBACK(_name)  NS_CALLBACK_(nsresult, _name)
+
+/**
+ * Import/Export macros for XPCOM APIs
+ */
+
+#ifdef __cplusplus
+#define NS_EXTERN_C extern "C"
+#else
+#define NS_EXTERN_C
+#endif
+
+#define EXPORT_XPCOM_API(type) NS_EXTERN_C NS_EXPORT type NS_FROZENCALL
+#define IMPORT_XPCOM_API(type) NS_EXTERN_C NS_IMPORT type NS_FROZENCALL
+#define GLUE_XPCOM_API(type) NS_EXTERN_C NS_HIDDEN_(type) NS_FROZENCALL
+
+#ifdef IMPL_LIBXUL
+#define XPCOM_API(type) EXPORT_XPCOM_API(type)
+#elif defined(XPCOM_GLUE)
+#define XPCOM_API(type) GLUE_XPCOM_API(type)
+#else
+#define XPCOM_API(type) IMPORT_XPCOM_API(type)
+#endif
+
+#ifdef MOZILLA_INTERNAL_API
+   /*
+     The frozen string API has different definitions of nsAC?String
+     classes than the internal API. On systems that explicitly declare
+     dllexport symbols this is not a problem, but on ELF systems
+     internal symbols can accidentally "shine through"; we rename the
+     internal classes to avoid symbol conflicts.
+   */
+#  define nsAString nsAString_internal
+#  define nsACString nsACString_internal
+#endif
+
+#if (defined(DEBUG) || defined(FORCE_BUILD_REFCNT_LOGGING))
+/* Make refcnt logging part of the build. This doesn't mean that
+ * actual logging will occur (that requires a separate enable; see
+ * nsTraceRefcnt and nsISupportsImpl.h for more information).  */
+#define NS_BUILD_REFCNT_LOGGING
+#endif
+
+/* If NO_BUILD_REFCNT_LOGGING is defined then disable refcnt logging
+ * in the build. This overrides FORCE_BUILD_REFCNT_LOGGING. */
+#if defined(NO_BUILD_REFCNT_LOGGING)
+#undef NS_BUILD_REFCNT_LOGGING
+#endif
+
+/* If a program allocates memory for the lifetime of the app, it doesn't make
+ * sense to touch memory pages and free that memory at shutdown,
+ * unless we are running leak stats.
+ */
+#if defined(NS_BUILD_REFCNT_LOGGING) || defined(MOZ_VALGRIND) || defined(MOZ_ASAN)
+#define NS_FREE_PERMANENT_DATA
+#endif
+
+/**
+ * NS_NO_VTABLE is emitted by xpidl in interface declarations whenever
+ * xpidl can determine that the interface can't contain a constructor.
+ * This results in some space savings and possible runtime savings -
+ * see bug 49416.  We undefine it first, as xpidl-generated headers
+ * define it for IDL uses that don't include this file.
+ */
+#ifdef NS_NO_VTABLE
+#undef NS_NO_VTABLE
+#endif
+#if defined(_MSC_VER)
+#define NS_NO_VTABLE __declspec(novtable)
+#else
+#define NS_NO_VTABLE
+#endif
+
+
+/**
+ * Generic XPCOM result data type
+ */
+#include "nsError.h"
+
+typedef MozRefCountType nsrefcnt;
+
+/*
+ * Use these macros to do 64bit safe pointer conversions.
+ */
+
+#define NS_PTR_TO_INT32(x) ((int32_t)(intptr_t)(x))
+#define NS_PTR_TO_UINT32(x) ((uint32_t)(intptr_t)(x))
+#define NS_INT32_TO_PTR(x) ((void*)(intptr_t)(x))
+
+/*
+ * Use NS_STRINGIFY to form a string literal from the value of a macro.
+ */
+#define NS_STRINGIFY_HELPER(x_) #x_
+#define NS_STRINGIFY(x_) NS_STRINGIFY_HELPER(x_)
+
+/*
+ * If we're being linked as standalone glue, we don't want a dynamic
+ * dependency on NSPR libs, so we skip the debug thread-safety
+ * checks, and we cannot use the THREADSAFE_ISUPPORTS macros.
+ */
+#if defined(XPCOM_GLUE) && !defined(XPCOM_GLUE_USE_NSPR)
+#define XPCOM_GLUE_AVOID_NSPR
+#endif
+
+/*
+ * SEH exception macros.
+ */
+#ifdef HAVE_SEH_EXCEPTIONS
+#define MOZ_SEH_TRY           __try
+#define MOZ_SEH_EXCEPT(expr)  __except(expr)
+#else
+#define MOZ_SEH_TRY           if(true)
+#define MOZ_SEH_EXCEPT(expr)  else
+#endif
+
+#endif /* nscore_h___ */
diff --git a/xpcom/base/nsrootidl.idl b/xpcom/base/nsrootidl.idl
new file mode 100644
index 000000000..55795b7bc
--- /dev/null
+++ b/xpcom/base/nsrootidl.idl
@@ -0,0 +1,97 @@
+/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * Root idl declarations to be used by all.
+ */
+
+%{C++
+
+#include "nscore.h"
+typedef int64_t PRTime;
+
+/*
+ * Forward declarations for new string types
+ */
+class nsAString;
+class nsACString;
+
+/* 
+ * Start commenting out the C++ versions of the below in the output header
+ */
+#if 0
+%}
+
+typedef boolean             bool   ;
+typedef octet               uint8_t  ;
+typedef unsigned short      uint16_t ;
+typedef unsigned short      char16_t;
+typedef unsigned long       uint32_t ;
+typedef unsigned long long  uint64_t ;
+typedef long long           PRTime   ;
+typedef short               int16_t  ;
+typedef long                int32_t  ;
+typedef long long           int64_t  ;
+
+typedef unsigned long       nsrefcnt ;
+typedef unsigned long       nsresult ;
+
+// XXX need this built into xpidl compiler so that it's really size_t or size_t
+// and it's scriptable:
+typedef unsigned long       size_t;
+
+[ptr]         native voidPtr(void);
+[ptr]         native charPtr(char);
+[ptr]         native unicharPtr(char16_t);
+
+[ref, nsid]   native nsIDRef(nsID);
+[ref, nsid]   native nsIIDRef(nsIID);
+[ref, nsid]   native nsCIDRef(nsCID);
+
+[ptr, nsid]   native nsIDPtr(nsID);
+[ptr, nsid]   native nsIIDPtr(nsIID);
+[ptr, nsid]   native nsCIDPtr(nsCID);
+
+// NOTE: Be careful in using the following 3 types. The *Ref and *Ptr variants 
+// are more commonly used (and better supported). Those variants require 
+// nsMemory alloc'd copies when used as 'out' params while these types do not. 
+// However, currently these types can not be used for 'in' params. And, methods 
+// that use them as 'out' params *must* be declared [notxpcom] (with an explicit 
+// return type of nsresult). This makes such methods implicitly not scriptable.
+// Use of these types in methods without a [notxpcom] declaration will cause
+// the xpidl compiler to raise an error.
+// See: http://bugzilla.mozilla.org/show_bug.cgi?id=93792
+
+[nsid]        native nsIID(nsIID);
+[nsid]        native nsID(nsID);
+[nsid]        native nsCID(nsCID);
+
+[ptr]         native nsQIResult(void);
+
+[ref, domstring] native DOMString(ignored);
+[ref, domstring] native DOMStringRef(ignored);
+[ptr, domstring] native DOMStringPtr(ignored);
+
+[ref, utf8string] native AUTF8String(ignored);
+[ref, utf8string] native AUTF8StringRef(ignored);
+[ptr, utf8string] native AUTF8StringPtr(ignored);
+
+[ref, cstring] native ACString(ignored);
+[ref, cstring] native ACStringRef(ignored);
+[ptr, cstring] native ACStringPtr(ignored);
+
+[ref, astring] native AString(ignored);
+[ref, astring] native AStringRef(ignored);
+[ptr, astring] native AStringPtr(ignored);
+
+[ref, jsval]  native jsval(jsval);
+              native jsid(jsid);
+
+%{C++
+/* 
+ * End commenting out the C++ versions of the above in the output header
+ */
+#endif
+%}
diff --git a/xpcom/build/BinaryPath.h b/xpcom/build/BinaryPath.h
new file mode 100644
index 000000000..374763c79
--- /dev/null
+++ b/xpcom/build/BinaryPath.h
@@ -0,0 +1,188 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_BinaryPath_h
+#define mozilla_BinaryPath_h
+
+#include "nsXPCOMPrivate.h" // for MAXPATHLEN
+#ifdef XP_WIN
+#include <windows.h>
+#elif defined(XP_MACOSX)
+#include <CoreFoundation/CoreFoundation.h>
+#elif defined(XP_UNIX)
+#include <sys/stat.h>
+#include <string.h>
+#endif
+
+namespace mozilla {
+
+class BinaryPath
+{
+public:
+#ifdef XP_WIN
+  static nsresult Get(const char* argv0, char aResult[MAXPATHLEN])
+  {
+    wchar_t wide_path[MAXPATHLEN];
+    nsresult rv = GetW(argv0, wide_path);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+    WideCharToMultiByte(CP_UTF8, 0, wide_path, -1,
+                        aResult, MAXPATHLEN, nullptr, nullptr);
+    return NS_OK;
+  }
+
+private:
+  static nsresult GetW(const char* argv0, wchar_t aResult[MAXPATHLEN])
+  {
+    if (::GetModuleFileNameW(0, aResult, MAXPATHLEN)) {
+      return NS_OK;
+    }
+    return NS_ERROR_FAILURE;
+  }
+
+#elif defined(XP_MACOSX)
+  static nsresult Get(const char* argv0, char aResult[MAXPATHLEN])
+  {
+    // Works even if we're not bundled.
+    CFBundleRef appBundle = CFBundleGetMainBundle();
+    if (!appBundle) {
+      return NS_ERROR_FAILURE;
+    }
+
+    CFURLRef executableURL = CFBundleCopyExecutableURL(appBundle);
+    if (!executableURL) {
+      return NS_ERROR_FAILURE;
+    }
+
+    nsresult rv;
+    if (CFURLGetFileSystemRepresentation(executableURL, false, (UInt8*)aResult,
+                                         MAXPATHLEN)) {
+      // Sanitize path in case the app was launched from Terminal via
+      // './firefox' for example.
+      size_t readPos = 0;
+      size_t writePos = 0;
+      while (aResult[readPos] != '\0') {
+        if (aResult[readPos] == '.' && aResult[readPos + 1] == '/') {
+          readPos += 2;
+        } else {
+          aResult[writePos] = aResult[readPos];
+          readPos++;
+          writePos++;
+        }
+      }
+      aResult[writePos] = '\0';
+      rv = NS_OK;
+    } else {
+      rv = NS_ERROR_FAILURE;
+    }
+
+    CFRelease(executableURL);
+    return rv;
+  }
+
+#elif defined(ANDROID)
+  static nsresult Get(const char* argv0, char aResult[MAXPATHLEN])
+  {
+    // On Android, we use the GRE_HOME variable that is set by the Java
+    // bootstrap code.
+    const char* greHome = getenv("GRE_HOME");
+#if defined(MOZ_WIDGET_GONK)
+    if (!greHome) {
+      greHome = "/system/b2g";
+    }
+#endif
+
+    if (!greHome) {
+      return NS_ERROR_FAILURE;
+    }
+
+    snprintf(aResult, MAXPATHLEN, "%s/%s", greHome, "dummy");
+    aResult[MAXPATHLEN - 1] = '\0';
+    return NS_OK;
+  }
+
+#elif defined(XP_UNIX)
+  static nsresult Get(const char* aArgv0, char aResult[MAXPATHLEN])
+  {
+    struct stat fileStat;
+    // on unix, there is no official way to get the path of the current binary.
+    // instead of using the MOZILLA_FIVE_HOME hack, which doesn't scale to
+    // multiple applications, we will try a series of techniques:
+    //
+    // 1) use realpath() on argv[0], which works unless we're loaded from the
+    //    PATH. Only do so if argv[0] looks like a path (contains a /).
+    // 2) manually walk through the PATH and look for ourself
+    // 3) give up
+    if (strchr(aArgv0, '/') && realpath(aArgv0, aResult) &&
+        stat(aResult, &fileStat) == 0) {
+      return NS_OK;
+    }
+
+    const char* path = getenv("PATH");
+    if (!path) {
+      return NS_ERROR_FAILURE;
+    }
+
+    char* pathdup = strdup(path);
+    if (!pathdup) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    bool found = false;
+    char* token = strtok(pathdup, ":");
+    while (token) {
+      char tmpPath[MAXPATHLEN];
+      sprintf(tmpPath, "%s/%s", token, aArgv0);
+      if (realpath(tmpPath, aResult) && stat(aResult, &fileStat) == 0) {
+        found = true;
+        break;
+      }
+      token = strtok(nullptr, ":");
+    }
+    free(pathdup);
+    if (found) {
+      return NS_OK;
+    }
+    return NS_ERROR_FAILURE;
+  }
+
+#else
+#error Oops, you need platform-specific code here
+#endif
+
+public:
+  static nsresult GetFile(const char* aArgv0, nsIFile** aResult)
+  {
+    nsCOMPtr<nsIFile> lf;
+#ifdef XP_WIN
+    wchar_t exePath[MAXPATHLEN];
+    nsresult rv = GetW(aArgv0, exePath);
+#else
+    char exePath[MAXPATHLEN];
+    nsresult rv = Get(aArgv0, exePath);
+#endif
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+#ifdef XP_WIN
+    rv = NS_NewLocalFile(nsDependentString(exePath), true,
+                         getter_AddRefs(lf));
+#else
+    rv = NS_NewNativeLocalFile(nsDependentCString(exePath), true,
+                               getter_AddRefs(lf));
+#endif
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+    NS_ADDREF(*aResult = lf);
+    return NS_OK;
+  }
+};
+
+} // namespace mozilla
+
+#endif /* mozilla_BinaryPath_h */
diff --git a/xpcom/build/FileLocation.cpp b/xpcom/build/FileLocation.cpp
new file mode 100644
index 000000000..03c1dc027
--- /dev/null
+++ b/xpcom/build/FileLocation.cpp
@@ -0,0 +1,224 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "FileLocation.h"
+#include "nsZipArchive.h"
+#include "nsURLHelper.h"
+
+namespace mozilla {
+
+FileLocation::FileLocation()
+{
+}
+
+FileLocation::~FileLocation()
+{
+}
+
+FileLocation::FileLocation(nsIFile* aFile)
+{
+  Init(aFile);
+}
+
+FileLocation::FileLocation(nsIFile* aFile, const char* aPath)
+{
+  Init(aFile, aPath);
+}
+
+FileLocation::FileLocation(const FileLocation& aFile, const char* aPath)
+{
+  if (aFile.IsZip()) {
+    if (aFile.mBaseFile) {
+      Init(aFile.mBaseFile, aFile.mPath.get());
+    }
+    else {
+      Init(aFile.mBaseZip, aFile.mPath.get());
+    }
+    if (aPath) {
+      int32_t i = mPath.RFindChar('/');
+      if (kNotFound == i) {
+        mPath.Truncate(0);
+      } else {
+        mPath.Truncate(i + 1);
+      }
+      mPath += aPath;
+    }
+  } else {
+    if (aPath) {
+      nsCOMPtr<nsIFile> cfile;
+      aFile.mBaseFile->GetParent(getter_AddRefs(cfile));
+
+#if defined(XP_WIN)
+      nsAutoCString pathStr(aPath);
+      char* p;
+      uint32_t len = pathStr.GetMutableData(&p);
+      for (; len; ++p, --len) {
+        if ('/' == *p) {
+          *p = '\\';
+        }
+      }
+      cfile->AppendRelativeNativePath(pathStr);
+#else
+      cfile->AppendRelativeNativePath(nsDependentCString(aPath));
+#endif
+      Init(cfile);
+    } else {
+      Init(aFile.mBaseFile);
+    }
+  }
+}
+
+void
+FileLocation::Init(nsIFile* aFile)
+{
+  mBaseZip = nullptr;
+  mBaseFile = aFile;
+  mPath.Truncate();
+}
+
+void
+FileLocation::Init(nsIFile* aFile, const char* aPath)
+{
+  mBaseZip = nullptr;
+  mBaseFile = aFile;
+  mPath = aPath;
+}
+
+void
+FileLocation::Init(nsZipArchive* aZip, const char* aPath)
+{
+  mBaseZip = aZip;
+  mBaseFile = nullptr;
+  mPath = aPath;
+}
+
+void
+FileLocation::GetURIString(nsACString& aResult) const
+{
+  if (mBaseFile) {
+    net_GetURLSpecFromActualFile(mBaseFile, aResult);
+  } else if (mBaseZip) {
+    RefPtr<nsZipHandle> handler = mBaseZip->GetFD();
+    handler->mFile.GetURIString(aResult);
+  }
+  if (IsZip()) {
+    aResult.Insert("jar:", 0);
+    aResult += "!/";
+    aResult += mPath;
+  }
+}
+
+already_AddRefed<nsIFile>
+FileLocation::GetBaseFile()
+{
+  if (IsZip() && mBaseZip) {
+    RefPtr<nsZipHandle> handler = mBaseZip->GetFD();
+    if (handler) {
+      return handler->mFile.GetBaseFile();
+    }
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIFile> file = mBaseFile;
+  return file.forget();
+}
+
+bool
+FileLocation::Equals(const FileLocation& aFile) const
+{
+  if (mPath != aFile.mPath) {
+    return false;
+  }
+
+  if (mBaseFile && aFile.mBaseFile) {
+    bool eq;
+    return NS_SUCCEEDED(mBaseFile->Equals(aFile.mBaseFile, &eq)) && eq;
+  }
+
+  const FileLocation* a = this;
+  const FileLocation* b = &aFile;
+  if (a->mBaseZip) {
+    RefPtr<nsZipHandle> handler = a->mBaseZip->GetFD();
+    a = &handler->mFile;
+  }
+  if (b->mBaseZip) {
+    RefPtr<nsZipHandle> handler = b->mBaseZip->GetFD();
+    b = &handler->mFile;
+  }
+
+  return a->Equals(*b);
+}
+
+nsresult
+FileLocation::GetData(Data& aData)
+{
+  if (!IsZip()) {
+    return mBaseFile->OpenNSPRFileDesc(PR_RDONLY, 0444, &aData.mFd.rwget());
+  }
+  aData.mZip = mBaseZip;
+  if (!aData.mZip) {
+    aData.mZip = new nsZipArchive();
+    aData.mZip->OpenArchive(mBaseFile);
+  }
+  aData.mItem = aData.mZip->GetItem(mPath.get());
+  if (aData.mItem) {
+    return NS_OK;
+  }
+  return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+}
+
+nsresult
+FileLocation::Data::GetSize(uint32_t* aResult)
+{
+  if (mFd) {
+    PRFileInfo64 fileInfo;
+    if (PR_SUCCESS != PR_GetOpenFileInfo64(mFd, &fileInfo)) {
+      return NS_ErrorAccordingToNSPR();
+    }
+
+    if (fileInfo.size > int64_t(UINT32_MAX)) {
+      return NS_ERROR_FILE_TOO_BIG;
+    }
+
+    *aResult = fileInfo.size;
+    return NS_OK;
+  }
+  else if (mItem) {
+    *aResult = mItem->RealSize();
+    return NS_OK;
+  }
+  return NS_ERROR_NOT_INITIALIZED;
+}
+
+nsresult
+FileLocation::Data::Copy(char* aBuf, uint32_t aLen)
+{
+  if (mFd) {
+    for (uint32_t totalRead = 0; totalRead < aLen;) {
+      int32_t read = PR_Read(mFd, aBuf + totalRead,
+                             XPCOM_MIN(aLen - totalRead, uint32_t(INT32_MAX)));
+      if (read < 0) {
+        return NS_ErrorAccordingToNSPR();
+      }
+      totalRead += read;
+    }
+    return NS_OK;
+  }
+  else if (mItem) {
+    nsZipCursor cursor(mItem, mZip, reinterpret_cast<uint8_t*>(aBuf),
+                       aLen, true);
+    uint32_t readLen;
+    cursor.Copy(&readLen);
+    if (readLen != aLen) {
+      nsZipArchive::sFileCorruptedReason = "FileLocation::Data: insufficient data";
+      return NS_ERROR_FILE_CORRUPTED;
+    }
+    return NS_OK;
+  }
+  return NS_ERROR_NOT_INITIALIZED;
+}
+
+} /* namespace mozilla */
diff --git a/xpcom/build/FileLocation.h b/xpcom/build/FileLocation.h
new file mode 100644
index 000000000..e9a3fc5d0
--- /dev/null
+++ b/xpcom/build/FileLocation.h
@@ -0,0 +1,134 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_FileLocation_h
+#define mozilla_FileLocation_h
+
+#include "nsString.h"
+#include "nsCOMPtr.h"
+#include "nsAutoPtr.h"
+#include "nsIFile.h"
+#include "FileUtils.h"
+
+class nsZipArchive;
+class nsZipItem;
+
+namespace mozilla {
+
+class FileLocation
+{
+public:
+  /**
+   * FileLocation is an helper to handle different kind of file locations
+   * within Gecko:
+   * - on filesystems
+   * - in archives
+   * - in archives within archives
+   * As such, it stores a path within an archive, as well as the archive
+   * path itself, or the complete file path alone when on a filesystem.
+   * When the archive is in an archive, an nsZipArchive is stored instead
+   * of a file path.
+   */
+  FileLocation();
+  ~FileLocation();
+
+  /**
+   * Constructor for plain files
+   */
+  explicit FileLocation(nsIFile* aFile);
+
+  /**
+   * Constructors for path within an archive. The archive can be given either
+   * as nsIFile or nsZipArchive.
+   */
+  FileLocation(nsIFile* aZip, const char* aPath);
+
+  FileLocation(nsZipArchive* aZip, const char* aPath);
+
+  /**
+   * Creates a new file location relative to another one.
+   */
+  FileLocation(const FileLocation& aFile, const char* aPath = nullptr);
+
+  /**
+   * Initialization functions corresponding to constructors
+   */
+  void Init(nsIFile* aFile);
+
+  void Init(nsIFile* aZip, const char* aPath);
+
+  void Init(nsZipArchive* aZip, const char* aPath);
+
+  /**
+   * Returns an URI string corresponding to the file location
+   */
+  void GetURIString(nsACString& aResult) const;
+
+  /**
+   * Returns the base file of the location, where base file is defined as:
+   * - The file itself when the location is on a filesystem
+   * - The archive file when the location is in an archive
+   * - The outer archive file when the location is in an archive in an archive
+   */
+  already_AddRefed<nsIFile> GetBaseFile();
+
+  /**
+   * Returns whether the "base file" (see GetBaseFile) is an archive
+   */
+  bool IsZip() const { return !mPath.IsEmpty(); }
+
+  /**
+   * Returns the path within the archive, when within an archive
+   */
+  void GetPath(nsACString& aResult) const { aResult = mPath; }
+
+  /**
+   * Boolean value corresponding to whether the file location is initialized
+   * or not.
+   */
+  explicit operator bool() const { return mBaseFile || mBaseZip; }
+
+  /**
+   * Returns whether another FileLocation points to the same resource
+   */
+  bool Equals(const FileLocation& aFile) const;
+
+  /**
+   * Data associated with a FileLocation.
+   */
+  class Data
+  {
+  public:
+    /**
+     * Returns the data size
+     */
+    nsresult GetSize(uint32_t* aResult);
+
+    /**
+     * Copies the data in the given buffer
+     */
+    nsresult Copy(char* aBuf, uint32_t aLen);
+  protected:
+    friend class FileLocation;
+    nsZipItem* mItem;
+    RefPtr<nsZipArchive> mZip;
+    mozilla::AutoFDClose mFd;
+  };
+
+  /**
+   * Returns the data associated with the resource pointed at by the file
+   * location.
+   */
+  nsresult GetData(Data& aData);
+private:
+  nsCOMPtr<nsIFile> mBaseFile;
+  RefPtr<nsZipArchive> mBaseZip;
+  nsCString mPath;
+}; /* class FileLocation */
+
+} /* namespace mozilla */
+
+#endif /* mozilla_FileLocation_h */
diff --git a/xpcom/build/FrozenFunctions.cpp b/xpcom/build/FrozenFunctions.cpp
new file mode 100644
index 000000000..8a957ca45
--- /dev/null
+++ b/xpcom/build/FrozenFunctions.cpp
@@ -0,0 +1,138 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsXPCOM.h"
+#include "nsXPCOMPrivate.h"
+#include "nsXPCOMStrings.h"
+#include "xptcall.h"
+
+#include <string.h>
+
+/**
+ * Private Method to register an exit routine.  This method
+ * used to allow you to setup a callback that will be called from
+ * the NS_ShutdownXPCOM function after all services and
+ * components have gone away. It was fatally flawed in that the component
+ * DLL could be released before the exit function was called; it is now a
+ * stub implementation that does nothing.
+ */
+XPCOM_API(nsresult)
+NS_RegisterXPCOMExitRoutine(XPCOMExitRoutine aExitRoutine, uint32_t aPriority);
+
+XPCOM_API(nsresult)
+NS_UnregisterXPCOMExitRoutine(XPCOMExitRoutine aExitRoutine);
+
+static const XPCOMFunctions kFrozenFunctions = {
+  XPCOM_GLUE_VERSION,
+  sizeof(XPCOMFunctions),
+  &NS_InitXPCOM2,
+  &NS_ShutdownXPCOM,
+  &NS_GetServiceManager,
+  &NS_GetComponentManager,
+  &NS_GetComponentRegistrar,
+  &NS_GetMemoryManager,
+  &NS_NewLocalFile,
+  &NS_NewNativeLocalFile,
+  &NS_RegisterXPCOMExitRoutine,
+  &NS_UnregisterXPCOMExitRoutine,
+
+  // these functions were added post 1.4
+  &NS_GetDebug,
+  nullptr,
+
+  // these functions were added post 1.6
+  &NS_StringContainerInit,
+  &NS_StringContainerFinish,
+  &NS_StringGetData,
+  &NS_StringSetData,
+  &NS_StringSetDataRange,
+  &NS_StringCopy,
+  &NS_CStringContainerInit,
+  &NS_CStringContainerFinish,
+  &NS_CStringGetData,
+  &NS_CStringSetData,
+  &NS_CStringSetDataRange,
+  &NS_CStringCopy,
+  &NS_CStringToUTF16,
+  &NS_UTF16ToCString,
+  &NS_StringCloneData,
+  &NS_CStringCloneData,
+
+  // these functions were added post 1.7 (post Firefox 1.0)
+  &moz_xmalloc,
+  &moz_xrealloc,
+  &free,
+  &NS_StringContainerInit2,
+  &NS_CStringContainerInit2,
+  &NS_StringGetMutableData,
+  &NS_CStringGetMutableData,
+  nullptr,
+
+  // these functions were added post 1.8
+  &NS_DebugBreak,
+  &NS_LogInit,
+  &NS_LogTerm,
+  &NS_LogAddRef,
+  &NS_LogRelease,
+  &NS_LogCtor,
+  &NS_LogDtor,
+  &NS_LogCOMPtrAddRef,
+  &NS_LogCOMPtrRelease,
+  &NS_GetXPTCallStub,
+  &NS_DestroyXPTCallStub,
+  &NS_InvokeByIndex,
+  nullptr,
+  nullptr,
+  &NS_StringSetIsVoid,
+  &NS_StringGetIsVoid,
+  &NS_CStringSetIsVoid,
+  &NS_CStringGetIsVoid,
+
+  // these functions were added post 1.9, but then made obsolete
+  nullptr,
+  nullptr,
+
+  &NS_CycleCollectorSuspect3,
+};
+
+EXPORT_XPCOM_API(nsresult)
+NS_GetFrozenFunctions(XPCOMFunctions* aFunctions, const char* /* aLibraryPath */)
+{
+  if (!aFunctions) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  if (aFunctions->version != XPCOM_GLUE_VERSION) {
+    return NS_ERROR_FAILURE;
+  }
+
+  uint32_t size = aFunctions->size;
+  if (size > sizeof(XPCOMFunctions)) {
+    size = sizeof(XPCOMFunctions);
+  }
+
+  size -= offsetof(XPCOMFunctions, init);
+
+  memcpy(&aFunctions->init, &kFrozenFunctions.init, size);
+
+  return NS_OK;
+}
+
+/*
+ * Stubs for nsXPCOMPrivate.h
+ */
+
+EXPORT_XPCOM_API(nsresult)
+NS_RegisterXPCOMExitRoutine(XPCOMExitRoutine aExitRoutine, uint32_t aPriority)
+{
+  return NS_OK;
+}
+
+EXPORT_XPCOM_API(nsresult)
+NS_UnregisterXPCOMExitRoutine(XPCOMExitRoutine aExitRoutine)
+{
+  return NS_OK;
+}
diff --git a/xpcom/build/IOInterposer.cpp b/xpcom/build/IOInterposer.cpp
new file mode 100644
index 000000000..1c3ff54d5
--- /dev/null
+++ b/xpcom/build/IOInterposer.cpp
@@ -0,0 +1,582 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <algorithm>
+#include <vector>
+
+#include "IOInterposer.h"
+
+#include "IOInterposerPrivate.h"
+#include "MainThreadIOLogger.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/ThreadLocal.h"
+#include "nscore.h" // for NS_FREE_PERMANENT_DATA
+#if !defined(XP_WIN)
+#include "NSPRInterposer.h"
+#endif // !defined(XP_WIN)
+#include "nsXULAppAPI.h"
+#include "PoisonIOInterposer.h"
+
+using namespace mozilla;
+
+namespace {
+
+/** Find if a vector contains a specific element */
+template<class T>
+bool
+VectorContains(const std::vector<T>& aVector, const T& aElement)
+{
+  return std::find(aVector.begin(), aVector.end(), aElement) != aVector.end();
+}
+
+/** Remove element from a vector */
+template<class T>
+void
+VectorRemove(std::vector<T>& aVector, const T& aElement)
+{
+  typename std::vector<T>::iterator newEnd =
+    std::remove(aVector.begin(), aVector.end(), aElement);
+  aVector.erase(newEnd, aVector.end());
+}
+
+/** Lists of Observers */
+struct ObserverLists
+{
+private:
+  ~ObserverLists() {}
+
+public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ObserverLists)
+
+  ObserverLists() {}
+
+  ObserverLists(ObserverLists const& aOther)
+    : mCreateObservers(aOther.mCreateObservers)
+    , mReadObservers(aOther.mReadObservers)
+    , mWriteObservers(aOther.mWriteObservers)
+    , mFSyncObservers(aOther.mFSyncObservers)
+    , mStatObservers(aOther.mStatObservers)
+    , mCloseObservers(aOther.mCloseObservers)
+    , mStageObservers(aOther.mStageObservers)
+  {
+  }
+  // Lists of observers for I/O events.
+  // These are implemented as vectors since they are allowed to survive gecko,
+  // without reporting leaks. This is necessary for the IOInterposer to be used
+  // for late-write checks.
+  std::vector<IOInterposeObserver*>  mCreateObservers;
+  std::vector<IOInterposeObserver*>  mReadObservers;
+  std::vector<IOInterposeObserver*>  mWriteObservers;
+  std::vector<IOInterposeObserver*>  mFSyncObservers;
+  std::vector<IOInterposeObserver*>  mStatObservers;
+  std::vector<IOInterposeObserver*>  mCloseObservers;
+  std::vector<IOInterposeObserver*>  mStageObservers;
+};
+
+class PerThreadData
+{
+public:
+  explicit PerThreadData(bool aIsMainThread = false)
+    : mIsMainThread(aIsMainThread)
+    , mIsHandlingObservation(false)
+    , mCurrentGeneration(0)
+  {
+    MOZ_COUNT_CTOR(PerThreadData);
+  }
+
+  ~PerThreadData()
+  {
+    MOZ_COUNT_DTOR(PerThreadData);
+  }
+
+  void CallObservers(IOInterposeObserver::Observation& aObservation)
+  {
+    // Prevent recursive reporting.
+    if (mIsHandlingObservation) {
+      return;
+    }
+
+    mIsHandlingObservation = true;
+    // Decide which list of observers to inform
+    std::vector<IOInterposeObserver*>* observers = nullptr;
+    switch (aObservation.ObservedOperation()) {
+      case IOInterposeObserver::OpCreateOrOpen:
+        observers = &mObserverLists->mCreateObservers;
+        break;
+      case IOInterposeObserver::OpRead:
+        observers = &mObserverLists->mReadObservers;
+        break;
+      case IOInterposeObserver::OpWrite:
+        observers = &mObserverLists->mWriteObservers;
+        break;
+      case IOInterposeObserver::OpFSync:
+        observers = &mObserverLists->mFSyncObservers;
+        break;
+      case IOInterposeObserver::OpStat:
+        observers = &mObserverLists->mStatObservers;
+        break;
+      case IOInterposeObserver::OpClose:
+        observers = &mObserverLists->mCloseObservers;
+        break;
+      case IOInterposeObserver::OpNextStage:
+        observers = &mObserverLists->mStageObservers;
+        break;
+      default: {
+        // Invalid IO operation, see documentation comment for
+        // IOInterposer::Report()
+        MOZ_ASSERT(false);
+        // Just ignore it in non-debug builds.
+        return;
+      }
+    }
+    MOZ_ASSERT(observers);
+
+    // Inform observers
+    for (auto i = observers->begin(), e = observers->end(); i != e; ++i) {
+      (*i)->Observe(aObservation);
+    }
+    mIsHandlingObservation = false;
+  }
+
+  inline uint32_t GetCurrentGeneration() const { return mCurrentGeneration; }
+
+  inline bool IsMainThread() const { return mIsMainThread; }
+
+  inline void SetObserverLists(uint32_t aNewGeneration,
+                               RefPtr<ObserverLists>& aNewLists)
+  {
+    mCurrentGeneration = aNewGeneration;
+    mObserverLists = aNewLists;
+  }
+
+  inline void ClearObserverLists()
+  {
+    if (mObserverLists) {
+      mCurrentGeneration = 0;
+      mObserverLists = nullptr;
+    }
+  }
+
+private:
+  bool                  mIsMainThread;
+  bool                  mIsHandlingObservation;
+  uint32_t              mCurrentGeneration;
+  RefPtr<ObserverLists> mObserverLists;
+};
+
+class MasterList
+{
+public:
+  MasterList()
+    : mObservedOperations(IOInterposeObserver::OpNone)
+    , mIsEnabled(true)
+  {
+    MOZ_COUNT_CTOR(MasterList);
+  }
+
+  ~MasterList()
+  {
+    MOZ_COUNT_DTOR(MasterList);
+  }
+
+  inline void Disable() { mIsEnabled = false; }
+  inline void Enable() { mIsEnabled = true; }
+
+  void Register(IOInterposeObserver::Operation aOp,
+                IOInterposeObserver* aObserver)
+  {
+    IOInterposer::AutoLock lock(mLock);
+
+    ObserverLists* newLists = nullptr;
+    if (mObserverLists) {
+      newLists = new ObserverLists(*mObserverLists);
+    } else {
+      newLists = new ObserverLists();
+    }
+    // You can register to observe multiple types of observations
+    // but you'll never be registered twice for the same observations.
+    if (aOp & IOInterposeObserver::OpCreateOrOpen &&
+        !VectorContains(newLists->mCreateObservers, aObserver)) {
+      newLists->mCreateObservers.push_back(aObserver);
+    }
+    if (aOp & IOInterposeObserver::OpRead &&
+        !VectorContains(newLists->mReadObservers, aObserver)) {
+      newLists->mReadObservers.push_back(aObserver);
+    }
+    if (aOp & IOInterposeObserver::OpWrite &&
+        !VectorContains(newLists->mWriteObservers, aObserver)) {
+      newLists->mWriteObservers.push_back(aObserver);
+    }
+    if (aOp & IOInterposeObserver::OpFSync &&
+        !VectorContains(newLists->mFSyncObservers, aObserver)) {
+      newLists->mFSyncObservers.push_back(aObserver);
+    }
+    if (aOp & IOInterposeObserver::OpStat &&
+        !VectorContains(newLists->mStatObservers, aObserver)) {
+      newLists->mStatObservers.push_back(aObserver);
+    }
+    if (aOp & IOInterposeObserver::OpClose &&
+        !VectorContains(newLists->mCloseObservers, aObserver)) {
+      newLists->mCloseObservers.push_back(aObserver);
+    }
+    if (aOp & IOInterposeObserver::OpNextStage &&
+        !VectorContains(newLists->mStageObservers, aObserver)) {
+      newLists->mStageObservers.push_back(aObserver);
+    }
+    mObserverLists = newLists;
+    mObservedOperations =
+      (IOInterposeObserver::Operation)(mObservedOperations | aOp);
+
+    mCurrentGeneration++;
+  }
+
+  void Unregister(IOInterposeObserver::Operation aOp,
+                  IOInterposeObserver* aObserver)
+  {
+    IOInterposer::AutoLock lock(mLock);
+
+    ObserverLists* newLists = nullptr;
+    if (mObserverLists) {
+      newLists = new ObserverLists(*mObserverLists);
+    } else {
+      newLists = new ObserverLists();
+    }
+
+    if (aOp & IOInterposeObserver::OpCreateOrOpen) {
+      VectorRemove(newLists->mCreateObservers, aObserver);
+      if (newLists->mCreateObservers.empty()) {
+        mObservedOperations =
+          (IOInterposeObserver::Operation)(mObservedOperations &
+                                           ~IOInterposeObserver::OpCreateOrOpen);
+      }
+    }
+    if (aOp & IOInterposeObserver::OpRead) {
+      VectorRemove(newLists->mReadObservers, aObserver);
+      if (newLists->mReadObservers.empty()) {
+        mObservedOperations =
+          (IOInterposeObserver::Operation)(mObservedOperations &
+                                           ~IOInterposeObserver::OpRead);
+      }
+    }
+    if (aOp & IOInterposeObserver::OpWrite) {
+      VectorRemove(newLists->mWriteObservers, aObserver);
+      if (newLists->mWriteObservers.empty()) {
+        mObservedOperations =
+          (IOInterposeObserver::Operation)(mObservedOperations &
+                                           ~IOInterposeObserver::OpWrite);
+      }
+    }
+    if (aOp & IOInterposeObserver::OpFSync) {
+      VectorRemove(newLists->mFSyncObservers, aObserver);
+      if (newLists->mFSyncObservers.empty()) {
+        mObservedOperations =
+          (IOInterposeObserver::Operation)(mObservedOperations &
+                                           ~IOInterposeObserver::OpFSync);
+      }
+    }
+    if (aOp & IOInterposeObserver::OpStat) {
+      VectorRemove(newLists->mStatObservers, aObserver);
+      if (newLists->mStatObservers.empty()) {
+        mObservedOperations =
+          (IOInterposeObserver::Operation)(mObservedOperations &
+                                           ~IOInterposeObserver::OpStat);
+      }
+    }
+    if (aOp & IOInterposeObserver::OpClose) {
+      VectorRemove(newLists->mCloseObservers, aObserver);
+      if (newLists->mCloseObservers.empty()) {
+        mObservedOperations =
+          (IOInterposeObserver::Operation)(mObservedOperations &
+                                           ~IOInterposeObserver::OpClose);
+      }
+    }
+    if (aOp & IOInterposeObserver::OpNextStage) {
+      VectorRemove(newLists->mStageObservers, aObserver);
+      if (newLists->mStageObservers.empty()) {
+        mObservedOperations =
+          (IOInterposeObserver::Operation)(mObservedOperations &
+                                           ~IOInterposeObserver::OpNextStage);
+      }
+    }
+    mObserverLists = newLists;
+    mCurrentGeneration++;
+  }
+
+  void Update(PerThreadData& aPtd)
+  {
+    if (mCurrentGeneration == aPtd.GetCurrentGeneration()) {
+      return;
+    }
+    // If the generation counts don't match then we need to update the current
+    // thread's observer list with the new master list.
+    IOInterposer::AutoLock lock(mLock);
+    aPtd.SetObserverLists(mCurrentGeneration, mObserverLists);
+  }
+
+  inline bool IsObservedOperation(IOInterposeObserver::Operation aOp)
+  {
+    // The quick reader may observe that no locks are being employed here,
+    // hence the result of the operations is truly undefined. However, most
+    // computers will usually return either true or false, which is good enough.
+    // It is not a problem if we occasionally report more or less IO than is
+    // actually occurring.
+    return mIsEnabled && !!(mObservedOperations & aOp);
+  }
+
+private:
+  RefPtr<ObserverLists>             mObserverLists;
+  // Note, we cannot use mozilla::Mutex here as the ObserverLists may be leaked
+  // (We want to monitor IO during shutdown). Furthermore, as we may have to
+  // unregister observers during shutdown an OffTheBooksMutex is not an option
+  // either, as its base calls into sDeadlockDetector which may be nullptr
+  // during shutdown.
+  IOInterposer::Mutex               mLock;
+  // Flags tracking which operations are being observed
+  IOInterposeObserver::Operation    mObservedOperations;
+  // Used for quickly disabling everything by IOInterposer::Disable()
+  Atomic<bool>                      mIsEnabled;
+  // Used to inform threads that the master observer list has changed
+  Atomic<uint32_t>                  mCurrentGeneration;
+};
+
+// Special observation used by IOInterposer::EnteringNextStage()
+class NextStageObservation : public IOInterposeObserver::Observation
+{
+public:
+  NextStageObservation()
+    : IOInterposeObserver::Observation(IOInterposeObserver::OpNextStage,
+                                       "IOInterposer", false)
+  {
+    mStart = TimeStamp::Now();
+    mEnd = mStart;
+  }
+};
+
+// List of observers registered
+static StaticAutoPtr<MasterList> sMasterList;
+static MOZ_THREAD_LOCAL(PerThreadData*) sThreadLocalData;
+static bool sThreadLocalDataInitialized;
+} // namespace
+
+IOInterposeObserver::Observation::Observation(Operation aOperation,
+                                              const char* aReference,
+                                              bool aShouldReport)
+  : mOperation(aOperation)
+  , mReference(aReference)
+  , mShouldReport(IOInterposer::IsObservedOperation(aOperation) &&
+                  aShouldReport)
+{
+  if (mShouldReport) {
+    mStart = TimeStamp::Now();
+  }
+}
+
+IOInterposeObserver::Observation::Observation(Operation aOperation,
+                                              const TimeStamp& aStart,
+                                              const TimeStamp& aEnd,
+                                              const char* aReference)
+  : mOperation(aOperation)
+  , mStart(aStart)
+  , mEnd(aEnd)
+  , mReference(aReference)
+  , mShouldReport(false)
+{
+}
+
+const char*
+IOInterposeObserver::Observation::ObservedOperationString() const
+{
+  switch (mOperation) {
+    case OpCreateOrOpen:
+      return "create/open";
+    case OpRead:
+      return "read";
+    case OpWrite:
+      return "write";
+    case OpFSync:
+      return "fsync";
+    case OpStat:
+      return "stat";
+    case OpClose:
+      return "close";
+    case OpNextStage:
+      return "NextStage";
+    default:
+      return "unknown";
+  }
+}
+
+void
+IOInterposeObserver::Observation::Report()
+{
+  if (mShouldReport) {
+    mEnd = TimeStamp::Now();
+    IOInterposer::Report(*this);
+  }
+}
+
+bool
+IOInterposer::Init()
+{
+  // Don't initialize twice...
+  if (sMasterList) {
+    return true;
+  }
+  if (!sThreadLocalData.init()) {
+    return false;
+  }
+  sThreadLocalDataInitialized = true;
+  bool isMainThread = true;
+  RegisterCurrentThread(isMainThread);
+  sMasterList = new MasterList();
+
+  MainThreadIOLogger::Init();
+
+  // Now we initialize the various interposers depending on platform
+  InitPoisonIOInterposer();
+  // We don't hook NSPR on Windows because PoisonIOInterposer captures a
+  // superset of the former's events.
+#if !defined(XP_WIN)
+  InitNSPRIOInterposing();
+#endif
+  return true;
+}
+
+bool
+IOInterposeObserver::IsMainThread()
+{
+  if (!sThreadLocalDataInitialized) {
+    return false;
+  }
+  PerThreadData* ptd = sThreadLocalData.get();
+  if (!ptd) {
+    return false;
+  }
+  return ptd->IsMainThread();
+}
+
+void
+IOInterposer::Clear()
+{
+  /* Clear() is a no-op on release builds so that we may continue to trap I/O
+     until process termination. In leak-checking builds, we need to shut down
+     IOInterposer so that all references are properly released. */
+#ifdef NS_FREE_PERMANENT_DATA
+  UnregisterCurrentThread();
+  sMasterList = nullptr;
+#endif
+}
+
+void
+IOInterposer::Disable()
+{
+  if (!sMasterList) {
+    return;
+  }
+  sMasterList->Disable();
+}
+
+void
+IOInterposer::Enable()
+{
+  if (!sMasterList) {
+    return;
+  }
+  sMasterList->Enable();
+}
+
+void
+IOInterposer::Report(IOInterposeObserver::Observation& aObservation)
+{
+  PerThreadData* ptd = sThreadLocalData.get();
+  if (!ptd) {
+    // In this case the current thread is not registered with IOInterposer.
+    // Alternatively we could take the slow path and just lock everything if
+    // we're not registered. That could potentially perform poorly, though.
+    return;
+  }
+
+  if (!sMasterList) {
+    // If there is no longer a master list then we should clear the local one.
+    ptd->ClearObserverLists();
+    return;
+  }
+
+  sMasterList->Update(*ptd);
+
+  // Don't try to report if there's nobody listening.
+  if (!IOInterposer::IsObservedOperation(aObservation.ObservedOperation())) {
+    return;
+  }
+
+  ptd->CallObservers(aObservation);
+}
+
+bool
+IOInterposer::IsObservedOperation(IOInterposeObserver::Operation aOp)
+{
+  return sMasterList && sMasterList->IsObservedOperation(aOp);
+}
+
+void
+IOInterposer::Register(IOInterposeObserver::Operation aOp,
+                       IOInterposeObserver* aObserver)
+{
+  MOZ_ASSERT(aObserver);
+  if (!sMasterList || !aObserver) {
+    return;
+  }
+
+  sMasterList->Register(aOp, aObserver);
+}
+
+void
+IOInterposer::Unregister(IOInterposeObserver::Operation aOp,
+                         IOInterposeObserver* aObserver)
+{
+  if (!sMasterList) {
+    return;
+  }
+
+  sMasterList->Unregister(aOp, aObserver);
+}
+
+void
+IOInterposer::RegisterCurrentThread(bool aIsMainThread)
+{
+  if (!sThreadLocalDataInitialized) {
+    return;
+  }
+  MOZ_ASSERT(!sThreadLocalData.get());
+  PerThreadData* curThreadData = new PerThreadData(aIsMainThread);
+  sThreadLocalData.set(curThreadData);
+}
+
+void
+IOInterposer::UnregisterCurrentThread()
+{
+  if (!sThreadLocalDataInitialized) {
+    return;
+  }
+  PerThreadData* curThreadData = sThreadLocalData.get();
+  MOZ_ASSERT(curThreadData);
+  sThreadLocalData.set(nullptr);
+  delete curThreadData;
+}
+
+void
+IOInterposer::EnteringNextStage()
+{
+  if (!sMasterList) {
+    return;
+  }
+  NextStageObservation observation;
+  Report(observation);
+}
+
diff --git a/xpcom/build/IOInterposer.h b/xpcom/build/IOInterposer.h
new file mode 100644
index 000000000..3634572a5
--- /dev/null
+++ b/xpcom/build/IOInterposer.h
@@ -0,0 +1,295 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_IOInterposer_h
+#define mozilla_IOInterposer_h
+
+#include "mozilla/Attributes.h"
+#include "mozilla/GuardObjects.h"
+#include "mozilla/TimeStamp.h"
+
+namespace mozilla {
+
+/**
+ * Interface for I/O interposer observers. This is separate from the
+ * IOInterposer because we have multiple uses for these observations.
+ */
+class IOInterposeObserver
+{
+public:
+  enum Operation
+  {
+    OpNone = 0,
+    OpCreateOrOpen = (1 << 0),
+    OpRead = (1 << 1),
+    OpWrite = (1 << 2),
+    OpFSync = (1 << 3),
+    OpStat = (1 << 4),
+    OpClose = (1 << 5),
+    OpNextStage = (1 << 6), // Meta - used when leaving startup, entering shutdown
+    OpWriteFSync = (OpWrite | OpFSync),
+    OpAll = (OpCreateOrOpen | OpRead | OpWrite | OpFSync | OpStat | OpClose),
+    OpAllWithStaging = (OpAll | OpNextStage)
+  };
+
+  /** A representation of an I/O observation  */
+  class Observation
+  {
+  protected:
+    /**
+     * This constructor is for use by subclasses that are intended to take
+     * timing measurements via RAII. The |aShouldReport| parameter may be
+     * used to make the measurement and reporting conditional on the
+     * satisfaction of an arbitrary predicate that was evaluated
+     * in the subclass. Note that IOInterposer::IsObservedOperation() is
+     * always ANDed with aShouldReport, so the subclass does not need to
+     * include a call to that function explicitly.
+     */
+    Observation(Operation aOperation, const char* aReference,
+                bool aShouldReport = true);
+
+  public:
+    /**
+     * Since this constructor accepts start and end times, it does *not* take
+     * its own timings, nor does it report itself.
+     */
+    Observation(Operation aOperation, const TimeStamp& aStart,
+                const TimeStamp& aEnd, const char* aReference);
+
+    /**
+     * Operation observed, this is one of the individual Operation values.
+     * Combinations of these flags are only used when registering observers.
+     */
+    Operation ObservedOperation() const { return mOperation; }
+
+    /**
+     * Return the observed operation as a human-readable string.
+     */
+    const char* ObservedOperationString() const;
+
+    /** Time at which the I/O operation was started */
+    TimeStamp Start() const { return mStart; }
+
+    /**
+     * Time at which the I/O operation ended, for asynchronous methods this is
+     * the time at which the call initiating the asynchronous request returned.
+     */
+    TimeStamp End() const { return mEnd; }
+
+    /**
+     * Duration of the operation, for asynchronous I/O methods this is the
+     * duration of the call initiating the asynchronous request.
+     */
+    TimeDuration Duration() const { return mEnd - mStart; }
+
+    /**
+     * IO reference, function name or name of component (sqlite) that did IO
+     * this is in addition the generic operation. This attribute may be platform
+     * specific, but should only take a finite number of distinct values.
+     * E.g. sqlite-commit, CreateFile, NtReadFile, fread, fsync, mmap, etc.
+     * I.e. typically the platform specific function that did the IO.
+     */
+    const char* Reference() const { return mReference; }
+
+    /** Request filename associated with the I/O operation, null if unknown */
+    virtual const char16_t* Filename() { return nullptr; }
+
+    virtual ~Observation() {}
+
+  protected:
+    void
+    Report();
+
+    Operation   mOperation;
+    TimeStamp   mStart;
+    TimeStamp   mEnd;
+    const char* mReference;     // Identifies the source of the Observation
+    bool        mShouldReport;  // Measure and report if true
+  };
+
+  /**
+   * Invoked whenever an implementation of the IOInterposeObserver should
+   * observe aObservation. Implement this and do your thing...
+   * But do consider if it is wise to use IO functions in this method, they are
+   * likely to cause recursion :)
+   * At least, see PoisonIOInterposer.h and register your handle as a debug file
+   * even, if you don't initialize the poison IO interposer, someone else might.
+   *
+   * Remark: Observations may occur on any thread.
+   */
+  virtual void Observe(Observation& aObservation) = 0;
+
+  virtual ~IOInterposeObserver() {}
+
+protected:
+  /**
+   * We don't use NS_IsMainThread() because we need to be able to determine the
+   * main thread outside of XPCOM Initialization. IOInterposer observers should
+   * call this function instead.
+   */
+  static bool IsMainThread();
+};
+
+/**
+ * These functions are responsible for ensuring that events are routed to the
+ * appropriate observers.
+ */
+namespace IOInterposer {
+
+/**
+ * This function must be called from the main-thread when no other threads are
+ * running before any of the other methods on this class may be used.
+ *
+ * IO reports can however, safely assume that IsObservedOperation() will
+ * return false until the IOInterposer is initialized.
+ *
+ * Remark, it's safe to call this method multiple times, so just call it when
+ * you to utilize IO interposing.
+ *
+ * Using the IOInterposerInit class is preferred to calling this directly.
+ */
+bool Init();
+
+/**
+ * This function must be called from the main thread, and furthermore
+ * it must be called when no other threads are executing. Effectively
+ * restricting us to calling it only during shutdown.
+ *
+ * Callers should take care that no other consumers are subscribed to events,
+ * as these events will stop when this function is called.
+ *
+ * In practice, we don't use this method as the IOInterposer is used for
+ * late-write checks.
+ */
+void Clear();
+
+/**
+ * This function immediately disables IOInterposer functionality in a fast,
+ * thread-safe manner. Primarily for use by the crash reporter.
+ */
+void Disable();
+
+/**
+ * This function re-enables IOInterposer functionality in a fast, thread-safe
+ * manner.  Primarily for use by the crash reporter.
+ */
+void Enable();
+
+/**
+ * Report IO to registered observers.
+ * Notice that the reported operation must be either OpRead, OpWrite or
+ * OpFSync. You are not allowed to report an observation with OpWriteFSync or
+ * OpAll, these are just auxiliary values for use with Register().
+ *
+ * If the IO call you're reporting does multiple things, write and fsync, you
+ * can choose to call Report() twice once with write and once with FSync. You
+ * may not call Report() with OpWriteFSync! The Observation::mOperation
+ * attribute is meant to be generic, not perfect.
+ *
+ * Notice that there is no reason to report an observation with an operation
+ * which is not being observed. Use IsObservedOperation() to check if the
+ * operation you are about to report is being observed. This is especially
+ * important if you are constructing expensive observations containing
+ * filename and full-path.
+ *
+ * Remark: Init() must be called before any IO is reported. But
+ * IsObservedOperation() will return false until Init() is called.
+ */
+void Report(IOInterposeObserver::Observation& aObservation);
+
+/**
+ * Return whether or not an operation is observed. Reporters should not
+ * report operations that are not being observed by anybody. This mechanism
+ * allows us to avoid reporting I/O when no observers are registered.
+ */
+bool IsObservedOperation(IOInterposeObserver::Operation aOp);
+
+/**
+ * Register IOInterposeObserver, the observer object will receive all
+ * observations for the given operation aOp.
+ *
+ * Remark: Init() must be called before observers are registered.
+ */
+void Register(IOInterposeObserver::Operation aOp,
+              IOInterposeObserver* aObserver);
+
+/**
+ * Unregister an IOInterposeObserver for a given operation
+ * Remark: It is always safe to unregister for all operations, even if yoú
+ * didn't register for them all.
+ * I.e. IOInterposer::Unregister(IOInterposeObserver::OpAll, aObserver)
+ *
+ * Remark: Init() must be called before observers are unregistered.
+ */
+void Unregister(IOInterposeObserver::Operation aOp,
+                IOInterposeObserver* aObserver);
+
+/**
+ * Registers the current thread with the IOInterposer. This must be done to
+ * ensure that per-thread data is created in an orderly fashion.
+ * We could have written this to initialize that data lazily, however this
+ * could have unintended consequences if a thread that is not aware of
+ * IOInterposer was implicitly registered: its per-thread data would never
+ * be deleted because it would not know to unregister itself.
+ *
+ * @param aIsMainThread true if IOInterposer should treat the current thread
+ *                      as the main thread.
+ */
+void RegisterCurrentThread(bool aIsMainThread = false);
+
+/**
+ * Unregisters the current thread with the IOInterposer. This is important
+ * to call when a thread is shutting down because it cleans up data that
+ * is stored in a TLS slot.
+ */
+void UnregisterCurrentThread();
+
+/**
+ * Called to inform observers that the process has transitioned out of the
+ * startup stage or into the shutdown stage. Main thread only.
+ */
+void EnteringNextStage();
+
+} // namespace IOInterposer
+
+class IOInterposerInit
+{
+public:
+  IOInterposerInit()
+  {
+#if !defined(RELEASE_OR_BETA)
+    IOInterposer::Init();
+#endif
+  }
+
+  ~IOInterposerInit()
+  {
+#if !defined(RELEASE_OR_BETA)
+    IOInterposer::Clear();
+#endif
+  }
+};
+
+class MOZ_RAII AutoIOInterposerDisable final
+{
+public:
+  explicit AutoIOInterposerDisable(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM)
+  {
+    MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+    IOInterposer::Disable();
+  }
+  ~AutoIOInterposerDisable()
+  {
+    IOInterposer::Enable();
+  }
+
+private:
+  MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
+};
+
+} // namespace mozilla
+
+#endif // mozilla_IOInterposer_h
diff --git a/xpcom/build/IOInterposerPrivate.h b/xpcom/build/IOInterposerPrivate.h
new file mode 100644
index 000000000..549321062
--- /dev/null
+++ b/xpcom/build/IOInterposerPrivate.h
@@ -0,0 +1,167 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef xpcom_build_IOInterposerPrivate_h
+#define xpcom_build_IOInterposerPrivate_h
+
+/* This header file contains declarations for helper classes that are
+   to be used exclusively by IOInterposer and its observers. This header
+   file is not to be used by anything else and MUST NOT be exported! */
+
+#include <prcvar.h>
+#include <prlock.h>
+
+namespace mozilla {
+namespace IOInterposer {
+
+/**
+ * The following classes are simple wrappers for PRLock and PRCondVar.
+ * IOInterposer and friends use these instead of Mozilla::Mutex et al because
+ * of the fact that IOInterposer is permitted to run until the process
+ * terminates; we can't use anything that plugs into leak checkers or deadlock
+ * detectors because IOInterposer will outlive those and generate false
+ * positives.
+ */
+
+class Monitor
+{
+public:
+  Monitor()
+    : mLock(PR_NewLock())
+    , mCondVar(PR_NewCondVar(mLock))
+  {
+  }
+
+  ~Monitor()
+  {
+    PR_DestroyCondVar(mCondVar);
+    mCondVar = nullptr;
+    PR_DestroyLock(mLock);
+    mLock = nullptr;
+  }
+
+  void Lock()
+  {
+    PR_Lock(mLock);
+  }
+
+  void Unlock()
+  {
+    PR_Unlock(mLock);
+  }
+
+  bool Wait(PRIntervalTime aTimeout = PR_INTERVAL_NO_TIMEOUT)
+  {
+    return PR_WaitCondVar(mCondVar, aTimeout) == PR_SUCCESS;
+  }
+
+  bool Notify()
+  {
+    return PR_NotifyCondVar(mCondVar) == PR_SUCCESS;
+  }
+
+private:
+  PRLock*    mLock;
+  PRCondVar* mCondVar;
+};
+
+class MonitorAutoLock
+{
+public:
+  explicit MonitorAutoLock(Monitor& aMonitor)
+    : mMonitor(aMonitor)
+  {
+    mMonitor.Lock();
+  }
+
+  ~MonitorAutoLock()
+  {
+    mMonitor.Unlock();
+  }
+
+  bool Wait(PRIntervalTime aTimeout = PR_INTERVAL_NO_TIMEOUT)
+  {
+    return mMonitor.Wait(aTimeout);
+  }
+
+  bool Notify()
+  {
+    return mMonitor.Notify();
+  }
+
+private:
+  Monitor&  mMonitor;
+};
+
+class MonitorAutoUnlock
+{
+public:
+  explicit MonitorAutoUnlock(Monitor& aMonitor)
+    : mMonitor(aMonitor)
+  {
+    mMonitor.Unlock();
+  }
+
+  ~MonitorAutoUnlock()
+  {
+    mMonitor.Lock();
+  }
+
+private:
+  Monitor&  mMonitor;
+};
+
+class Mutex
+{
+public:
+  Mutex()
+    : mPRLock(PR_NewLock())
+  {
+  }
+
+  ~Mutex()
+  {
+    PR_DestroyLock(mPRLock);
+    mPRLock = nullptr;
+  }
+
+  void Lock()
+  {
+    PR_Lock(mPRLock);
+  }
+
+  void Unlock()
+  {
+    PR_Unlock(mPRLock);
+  }
+
+private:
+  PRLock*   mPRLock;
+};
+
+class AutoLock
+{
+public:
+  explicit AutoLock(Mutex& aLock)
+    : mLock(aLock)
+  {
+    mLock.Lock();
+  }
+
+  ~AutoLock()
+  {
+    mLock.Unlock();
+  }
+
+private:
+  Mutex&     mLock;
+};
+
+} // namespace IOInterposer
+} // namespace mozilla
+
+#endif // xpcom_build_IOInterposerPrivate_h
+
diff --git a/xpcom/build/LateWriteChecks.cpp b/xpcom/build/LateWriteChecks.cpp
new file mode 100644
index 000000000..69dbedc0f
--- /dev/null
+++ b/xpcom/build/LateWriteChecks.cpp
@@ -0,0 +1,258 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <algorithm>
+
+#include "mozilla/IOInterposer.h"
+#include "mozilla/PoisonIOInterposer.h"
+#include "mozilla/ProcessedStack.h"
+#include "mozilla/SHA1.h"
+#include "mozilla/Scoped.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/Telemetry.h"
+#include "nsAppDirectoryServiceDefs.h"
+#include "nsDirectoryServiceUtils.h"
+#include "nsPrintfCString.h"
+#include "mozilla/StackWalk.h"
+#include "plstr.h"
+#include "prio.h"
+
+#ifdef XP_WIN
+#define NS_T(str) L ## str
+#define NS_SLASH "\\"
+#include <fcntl.h>
+#include <io.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <windows.h>
+#else
+#define NS_SLASH "/"
+#endif
+
+#include "LateWriteChecks.h"
+
+#define OBSERVE_LATE_WRITES
+
+using namespace mozilla;
+
+/*************************** Auxiliary Declarations ***************************/
+
+// This a wrapper over a file descriptor that provides a Printf method and
+// computes the sha1 of the data that passes through it.
+class SHA1Stream
+{
+public:
+  explicit SHA1Stream(FILE* aStream)
+    : mFile(aStream)
+  {
+    MozillaRegisterDebugFILE(mFile);
+  }
+
+  void Printf(const char* aFormat, ...)
+  {
+    MOZ_ASSERT(mFile);
+    va_list list;
+    va_start(list, aFormat);
+    nsAutoCString str;
+    str.AppendPrintf(aFormat, list);
+    va_end(list);
+    mSHA1.update(str.get(), str.Length());
+    fwrite(str.get(), 1, str.Length(), mFile);
+  }
+  void Finish(SHA1Sum::Hash& aHash)
+  {
+    int fd = fileno(mFile);
+    fflush(mFile);
+    MozillaUnRegisterDebugFD(fd);
+    fclose(mFile);
+    mSHA1.finish(aHash);
+    mFile = nullptr;
+  }
+private:
+  FILE* mFile;
+  SHA1Sum mSHA1;
+};
+
+static void
+RecordStackWalker(uint32_t aFrameNumber, void* aPC, void* aSP, void* aClosure)
+{
+  std::vector<uintptr_t>* stack =
+    static_cast<std::vector<uintptr_t>*>(aClosure);
+  stack->push_back(reinterpret_cast<uintptr_t>(aPC));
+}
+
+/**************************** Late-Write Observer  ****************************/
+
+/**
+ * An implementation of IOInterposeObserver to be registered with IOInterposer.
+ * This observer logs all writes as late writes.
+ */
+class LateWriteObserver final : public IOInterposeObserver
+{
+public:
+  explicit LateWriteObserver(const char* aProfileDirectory)
+    : mProfileDirectory(PL_strdup(aProfileDirectory))
+  {
+  }
+  ~LateWriteObserver()
+  {
+    PL_strfree(mProfileDirectory);
+    mProfileDirectory = nullptr;
+  }
+
+  void Observe(IOInterposeObserver::Observation& aObservation);
+private:
+  char* mProfileDirectory;
+};
+
+void
+LateWriteObserver::Observe(IOInterposeObserver::Observation& aOb)
+{
+#ifdef OBSERVE_LATE_WRITES
+  // Crash if that is the shutdown check mode
+  if (gShutdownChecks == SCM_CRASH) {
+    MOZ_CRASH();
+  }
+
+  // If we have shutdown mode SCM_NOTHING or we can't record then abort
+  if (gShutdownChecks == SCM_NOTHING || !Telemetry::CanRecordExtended()) {
+    return;
+  }
+
+  // Write the stack and loaded libraries to a file. We can get here
+  // concurrently from many writes, so we use multiple temporary files.
+  std::vector<uintptr_t> rawStack;
+
+  MozStackWalk(RecordStackWalker, /* skipFrames */ 0, /* maxFrames */ 0,
+               reinterpret_cast<void*>(&rawStack), 0, nullptr);
+  Telemetry::ProcessedStack stack = Telemetry::GetStackAndModules(rawStack);
+
+  nsPrintfCString nameAux("%s%s%s", mProfileDirectory,
+                          NS_SLASH, "Telemetry.LateWriteTmpXXXXXX");
+  char* name;
+  nameAux.GetMutableData(&name);
+
+  // We want the sha1 of the entire file, so please don't write to fd
+  // directly; use sha1Stream.
+  FILE* stream;
+#ifdef XP_WIN
+  HANDLE hFile;
+  do {
+    // mkstemp isn't supported so keep trying until we get a file
+    int result = _mktemp_s(name, strlen(name) + 1);
+    hFile = CreateFileA(name, GENERIC_WRITE, 0, nullptr, CREATE_NEW,
+                        FILE_ATTRIBUTE_NORMAL, nullptr);
+  } while (GetLastError() == ERROR_FILE_EXISTS);
+
+  if (hFile == INVALID_HANDLE_VALUE) {
+    NS_RUNTIMEABORT("Um, how did we get here?");
+  }
+
+  // http://support.microsoft.com/kb/139640
+  int fd = _open_osfhandle((intptr_t)hFile, _O_APPEND);
+  if (fd == -1) {
+    NS_RUNTIMEABORT("Um, how did we get here?");
+  }
+
+  stream = _fdopen(fd, "w");
+#else
+  int fd = mkstemp(name);
+  stream = fdopen(fd, "w");
+#endif
+
+  SHA1Stream sha1Stream(stream);
+
+  size_t numModules = stack.GetNumModules();
+  sha1Stream.Printf("%u\n", (unsigned)numModules);
+  for (size_t i = 0; i < numModules; ++i) {
+    Telemetry::ProcessedStack::Module module = stack.GetModule(i);
+    sha1Stream.Printf("%s %s\n", module.mBreakpadId.c_str(),
+                      module.mName.c_str());
+  }
+
+  size_t numFrames = stack.GetStackSize();
+  sha1Stream.Printf("%u\n", (unsigned)numFrames);
+  for (size_t i = 0; i < numFrames; ++i) {
+    const Telemetry::ProcessedStack::Frame& frame = stack.GetFrame(i);
+    // NOTE: We write the offsets, while the atos tool expects a value with
+    // the virtual address added. For example, running otool -l on the the firefox
+    // binary shows
+    //      cmd LC_SEGMENT_64
+    //      cmdsize 632
+    //      segname __TEXT
+    //      vmaddr 0x0000000100000000
+    // so to print the line matching the offset 123 one has to run
+    // atos -o firefox 0x100000123.
+    sha1Stream.Printf("%d %x\n", frame.mModIndex, (unsigned)frame.mOffset);
+  }
+
+  SHA1Sum::Hash sha1;
+  sha1Stream.Finish(sha1);
+
+  // Note: These files should be deleted by telemetry once it reads them. If
+  // there were no telemetry runs by the time we shut down, we just add files
+  // to the existing ones instead of replacing them. Given that each of these
+  // files is a bug to be fixed, that is probably the right thing to do.
+
+  // We append the sha1 of the contents to the file name. This provides a simple
+  // client side deduplication.
+  nsPrintfCString finalName("%s%s", mProfileDirectory,
+                            "/Telemetry.LateWriteFinal-");
+  for (int i = 0; i < 20; ++i) {
+    finalName.AppendPrintf("%02x", sha1[i]);
+  }
+  PR_Delete(finalName.get());
+  PR_Rename(name, finalName.get());
+#endif
+}
+
+/******************************* Setup/Teardown *******************************/
+
+static StaticAutoPtr<LateWriteObserver> sLateWriteObserver;
+
+namespace mozilla {
+
+void
+InitLateWriteChecks()
+{
+  nsCOMPtr<nsIFile> mozFile;
+  NS_GetSpecialDirectory(NS_APP_USER_PROFILE_50_DIR, getter_AddRefs(mozFile));
+  if (mozFile) {
+    nsAutoCString nativePath;
+    nsresult rv = mozFile->GetNativePath(nativePath);
+    if (NS_SUCCEEDED(rv) && nativePath.get()) {
+      sLateWriteObserver = new LateWriteObserver(nativePath.get());
+    }
+  }
+}
+
+void
+BeginLateWriteChecks()
+{
+  if (sLateWriteObserver) {
+    IOInterposer::Register(
+      IOInterposeObserver::OpWriteFSync,
+      sLateWriteObserver
+    );
+  }
+}
+
+void
+StopLateWriteChecks()
+{
+  if (sLateWriteObserver) {
+    IOInterposer::Unregister(
+      IOInterposeObserver::OpAll,
+      sLateWriteObserver
+    );
+    // Deallocation would not be thread-safe, and StopLateWriteChecks() is
+    // called at shutdown and only in special cases.
+    // sLateWriteObserver = nullptr;
+  }
+}
+
+} // namespace mozilla
diff --git a/xpcom/build/LateWriteChecks.h b/xpcom/build/LateWriteChecks.h
new file mode 100644
index 000000000..96d981cc1
--- /dev/null
+++ b/xpcom/build/LateWriteChecks.h
@@ -0,0 +1,60 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_LateWriteChecks_h
+#define mozilla_LateWriteChecks_h
+
+// This file, along with LateWriteChecks.cpp, serves to check for and report
+// late writes. The idea is discover writes to the file system that happens
+// during shutdown such that these maybe be moved forward and the process may be
+// killed without waiting for static destructors.
+
+namespace mozilla {
+
+/** Different shutdown check modes */
+enum ShutdownChecksMode
+{
+  SCM_CRASH,      /** Crash on shutdown check failure */
+  SCM_RECORD,     /** Record shutdown check violations */
+  SCM_NOTHING     /** Don't attempt any shutdown checks */
+};
+
+/**
+ * Current shutdown check mode.
+ * This variable is defined and initialized in nsAppRunner.cpp
+ */
+extern ShutdownChecksMode gShutdownChecks;
+
+/**
+ * Allocate structures and acquire information from XPCOM necessary to do late
+ * write checks. This function must be invoked before BeginLateWriteChecks()
+ * and before XPCOM has stopped working.
+ */
+void InitLateWriteChecks();
+
+/**
+ * Begin recording all writes as late-writes. This function should be called
+ * when all legitimate writes have occurred. This function does not rely on
+ * XPCOM as it is designed to be invoked during XPCOM shutdown.
+ *
+ * For late-write checks to work you must initialize one or more backends that
+ * reports IO through the IOInterposer API. PoisonIOInterposer would probably
+ * be the backend of choice in this case.
+ *
+ * Note: BeginLateWriteChecks() must have been invoked before this function.
+ */
+void BeginLateWriteChecks();
+
+/**
+ * Stop recording all writes as late-writes, call this function when you want
+ * late-write checks to stop. I.e. exception handling, or the special case on
+ * Mac described in bug 826029.
+ */
+void StopLateWriteChecks();
+
+} // namespace mozilla
+
+#endif // mozilla_LateWriteChecks_h
diff --git a/xpcom/build/MainThreadIOLogger.cpp b/xpcom/build/MainThreadIOLogger.cpp
new file mode 100644
index 000000000..0ca942cb9
--- /dev/null
+++ b/xpcom/build/MainThreadIOLogger.cpp
@@ -0,0 +1,225 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "MainThreadIOLogger.h"
+
+#include "GeckoProfiler.h"
+#include "IOInterposerPrivate.h"
+#include "mozilla/IOInterposer.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/TimeStamp.h"
+#include "nsAutoPtr.h"
+#include "nsNativeCharsetUtils.h"
+
+/**
+ * This code uses NSPR stuff and STL containers because it must be detached
+ * from leak checking code; this observer runs until the process terminates.
+ */
+
+#include <prenv.h>
+#include <prprf.h>
+#include <prthread.h>
+#include <vector>
+
+namespace {
+
+struct ObservationWithStack
+{
+  ObservationWithStack(mozilla::IOInterposeObserver::Observation& aObs,
+                       ProfilerBacktrace* aStack)
+    : mObservation(aObs)
+    , mStack(aStack)
+  {
+    const char16_t* filename = aObs.Filename();
+    if (filename) {
+      mFilename = filename;
+    }
+  }
+
+  mozilla::IOInterposeObserver::Observation mObservation;
+  ProfilerBacktrace*                        mStack;
+  nsString                                  mFilename;
+};
+
+class MainThreadIOLoggerImpl final : public mozilla::IOInterposeObserver
+{
+public:
+  MainThreadIOLoggerImpl();
+  ~MainThreadIOLoggerImpl();
+
+  bool Init();
+
+  void Observe(Observation& aObservation);
+
+private:
+  static void sIOThreadFunc(void* aArg);
+  void IOThreadFunc();
+
+  TimeStamp             mLogStartTime;
+  const char*           mFileName;
+  PRThread*             mIOThread;
+  IOInterposer::Monitor mMonitor;
+  bool                  mShutdownRequired;
+  std::vector<ObservationWithStack> mObservations;
+};
+
+static StaticAutoPtr<MainThreadIOLoggerImpl> sImpl;
+
+MainThreadIOLoggerImpl::MainThreadIOLoggerImpl()
+  : mFileName(nullptr)
+  , mIOThread(nullptr)
+  , mShutdownRequired(false)
+{
+}
+
+MainThreadIOLoggerImpl::~MainThreadIOLoggerImpl()
+{
+  if (!mIOThread) {
+    return;
+  }
+  {
+    // Scope for lock
+    IOInterposer::MonitorAutoLock lock(mMonitor);
+    mShutdownRequired = true;
+    lock.Notify();
+  }
+  PR_JoinThread(mIOThread);
+  mIOThread = nullptr;
+}
+
+bool
+MainThreadIOLoggerImpl::Init()
+{
+  if (mFileName) {
+    // Already initialized
+    return true;
+  }
+  mFileName = PR_GetEnv("MOZ_MAIN_THREAD_IO_LOG");
+  if (!mFileName) {
+    // Can't start
+    return false;
+  }
+  mIOThread = PR_CreateThread(PR_USER_THREAD, &sIOThreadFunc, this,
+                              PR_PRIORITY_LOW, PR_GLOBAL_THREAD,
+                              PR_JOINABLE_THREAD, 0);
+  if (!mIOThread) {
+    return false;
+  }
+  return true;
+}
+
+/* static */ void
+MainThreadIOLoggerImpl::sIOThreadFunc(void* aArg)
+{
+  PR_SetCurrentThreadName("MainThreadIOLogger");
+  MainThreadIOLoggerImpl* obj = static_cast<MainThreadIOLoggerImpl*>(aArg);
+  obj->IOThreadFunc();
+}
+
+void
+MainThreadIOLoggerImpl::IOThreadFunc()
+{
+  PRFileDesc* fd = PR_Open(mFileName, PR_WRONLY | PR_CREATE_FILE | PR_TRUNCATE,
+                           PR_IRUSR | PR_IWUSR | PR_IRGRP);
+  if (!fd) {
+    IOInterposer::MonitorAutoLock lock(mMonitor);
+    mShutdownRequired = true;
+    std::vector<ObservationWithStack>().swap(mObservations);
+    return;
+  }
+  mLogStartTime = TimeStamp::Now();
+  {
+    // Scope for lock
+    IOInterposer::MonitorAutoLock lock(mMonitor);
+    while (true) {
+      while (!mShutdownRequired && mObservations.empty()) {
+        lock.Wait();
+      }
+      if (mShutdownRequired) {
+        break;
+      }
+      // Pull events off the shared array onto a local one
+      std::vector<ObservationWithStack> observationsToWrite;
+      observationsToWrite.swap(mObservations);
+
+      // Release the lock so that we're not holding anybody up during I/O
+      IOInterposer::MonitorAutoUnlock unlock(mMonitor);
+
+      // Now write the events.
+      for (auto i = observationsToWrite.begin(), e = observationsToWrite.end();
+           i != e; ++i) {
+        if (i->mObservation.ObservedOperation() == OpNextStage) {
+          PR_fprintf(fd, "%f,NEXT-STAGE\n",
+                     (TimeStamp::Now() - mLogStartTime).ToMilliseconds());
+          continue;
+        }
+        double durationMs = i->mObservation.Duration().ToMilliseconds();
+        nsAutoCString nativeFilename;
+        nativeFilename.AssignLiteral("(not available)");
+        if (!i->mFilename.IsEmpty()) {
+          if (NS_FAILED(NS_CopyUnicodeToNative(i->mFilename, nativeFilename))) {
+            nativeFilename.AssignLiteral("(conversion failed)");
+          }
+        }
+        /**
+         * Format:
+         * Start Timestamp (Milliseconds), Operation, Duration (Milliseconds), Event Source, Filename
+         */
+        if (PR_fprintf(fd, "%f,%s,%f,%s,%s\n",
+                       (i->mObservation.Start() - mLogStartTime).ToMilliseconds(),
+                       i->mObservation.ObservedOperationString(), durationMs,
+                       i->mObservation.Reference(), nativeFilename.get()) > 0) {
+          ProfilerBacktrace* stack = i->mStack;
+          if (stack) {
+            // TODO: Write out the callstack
+            //       (This will be added in a later bug)
+            profiler_free_backtrace(stack);
+          }
+        }
+      }
+    }
+  }
+  PR_Close(fd);
+}
+
+void
+MainThreadIOLoggerImpl::Observe(Observation& aObservation)
+{
+  if (!mFileName || !IsMainThread()) {
+    return;
+  }
+  IOInterposer::MonitorAutoLock lock(mMonitor);
+  if (mShutdownRequired) {
+    // The writer thread isn't running. Don't enqueue any more data.
+    return;
+  }
+  // Passing nullptr as aStack parameter for now
+  mObservations.push_back(ObservationWithStack(aObservation, nullptr));
+  lock.Notify();
+}
+
+} // namespace
+
+namespace mozilla {
+
+namespace MainThreadIOLogger {
+
+bool
+Init()
+{
+  nsAutoPtr<MainThreadIOLoggerImpl> impl(new MainThreadIOLoggerImpl());
+  if (!impl->Init()) {
+    return false;
+  }
+  sImpl = impl.forget();
+  IOInterposer::Register(IOInterposeObserver::OpAllWithStaging, sImpl);
+  return true;
+}
+
+} // namespace MainThreadIOLogger
+
+} // namespace mozilla
+
diff --git a/xpcom/build/MainThreadIOLogger.h b/xpcom/build/MainThreadIOLogger.h
new file mode 100644
index 000000000..df9e30b53
--- /dev/null
+++ b/xpcom/build/MainThreadIOLogger.h
@@ -0,0 +1,19 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_MainThreadIOLogger_h
+#define mozilla_MainThreadIOLogger_h
+
+namespace mozilla {
+namespace MainThreadIOLogger {
+
+bool Init();
+
+} // namespace MainThreadIOLogger
+} // namespace mozilla
+
+#endif // mozilla_MainThreadIOLogger_h
+
diff --git a/xpcom/build/NSPRInterposer.cpp b/xpcom/build/NSPRInterposer.cpp
new file mode 100644
index 000000000..a7c53a97a
--- /dev/null
+++ b/xpcom/build/NSPRInterposer.cpp
@@ -0,0 +1,185 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "IOInterposer.h"
+#include "NSPRInterposer.h"
+
+#include "prio.h"
+#include "private/pprio.h"
+#include "nsDebug.h"
+#include "nscore.h"
+
+namespace {
+
+using namespace mozilla;
+
+/* Original IO methods */
+PRCloseFN sCloseFn = nullptr;
+PRReadFN  sReadFn  = nullptr;
+PRWriteFN sWriteFn = nullptr;
+PRFsyncFN sFSyncFn = nullptr;
+PRFileInfoFN sFileInfoFn = nullptr;
+PRFileInfo64FN sFileInfo64Fn = nullptr;
+
+/**
+ * RAII class for timing the duration of an NSPR I/O call and reporting the
+ * result to the IOInterposeObserver API.
+ */
+class NSPRIOAutoObservation : public IOInterposeObserver::Observation
+{
+public:
+  explicit NSPRIOAutoObservation(IOInterposeObserver::Operation aOp)
+    : IOInterposeObserver::Observation(aOp, "NSPRIOInterposer")
+  {
+  }
+
+  ~NSPRIOAutoObservation()
+  {
+    Report();
+  }
+};
+
+PRStatus PR_CALLBACK
+interposedClose(PRFileDesc* aFd)
+{
+  // If we don't have a valid original function pointer something is very wrong.
+  NS_ASSERTION(sCloseFn, "NSPR IO Interposing: sCloseFn is NULL");
+
+  NSPRIOAutoObservation timer(IOInterposeObserver::OpClose);
+  return sCloseFn(aFd);
+}
+
+int32_t PR_CALLBACK
+interposedRead(PRFileDesc* aFd, void* aBuf, int32_t aAmt)
+{
+  // If we don't have a valid original function pointer something is very wrong.
+  NS_ASSERTION(sReadFn, "NSPR IO Interposing: sReadFn is NULL");
+
+  NSPRIOAutoObservation timer(IOInterposeObserver::OpRead);
+  return sReadFn(aFd, aBuf, aAmt);
+}
+
+int32_t PR_CALLBACK
+interposedWrite(PRFileDesc* aFd, const void* aBuf, int32_t aAmt)
+{
+  // If we don't have a valid original function pointer something is very wrong.
+  NS_ASSERTION(sWriteFn, "NSPR IO Interposing: sWriteFn is NULL");
+
+  NSPRIOAutoObservation timer(IOInterposeObserver::OpWrite);
+  return sWriteFn(aFd, aBuf, aAmt);
+}
+
+PRStatus PR_CALLBACK
+interposedFSync(PRFileDesc* aFd)
+{
+  // If we don't have a valid original function pointer something is very wrong.
+  NS_ASSERTION(sFSyncFn, "NSPR IO Interposing: sFSyncFn is NULL");
+
+  NSPRIOAutoObservation timer(IOInterposeObserver::OpFSync);
+  return sFSyncFn(aFd);
+}
+
+PRStatus PR_CALLBACK
+interposedFileInfo(PRFileDesc* aFd, PRFileInfo* aInfo)
+{
+  // If we don't have a valid original function pointer something is very wrong.
+  NS_ASSERTION(sFileInfoFn, "NSPR IO Interposing: sFileInfoFn is NULL");
+
+  NSPRIOAutoObservation timer(IOInterposeObserver::OpStat);
+  return sFileInfoFn(aFd, aInfo);
+}
+
+PRStatus PR_CALLBACK
+interposedFileInfo64(PRFileDesc* aFd, PRFileInfo64* aInfo)
+{
+  // If we don't have a valid original function pointer something is very wrong.
+  NS_ASSERTION(sFileInfo64Fn, "NSPR IO Interposing: sFileInfo64Fn is NULL");
+
+  NSPRIOAutoObservation timer(IOInterposeObserver::OpStat);
+  return sFileInfo64Fn(aFd, aInfo);
+}
+
+} // namespace
+
+namespace mozilla {
+
+void
+InitNSPRIOInterposing()
+{
+  // Check that we have not interposed any of the IO methods before
+  MOZ_ASSERT(!sCloseFn && !sReadFn && !sWriteFn && !sFSyncFn && !sFileInfoFn &&
+             !sFileInfo64Fn);
+
+  // We can't actually use this assertion because we initialize this code
+  // before XPCOM is initialized, so NS_IsMainThread() always returns false.
+  // MOZ_ASSERT(NS_IsMainThread());
+
+  // Get IO methods from NSPR and const cast the structure so we can modify it.
+  PRIOMethods* methods = const_cast<PRIOMethods*>(PR_GetFileMethods());
+
+  // Something is badly wrong if we don't get IO methods... However, we don't
+  // want to crash over that in non-debug builds. This is unlikely to happen
+  // so an assert is enough, no need to report it to the caller.
+  MOZ_ASSERT(methods);
+  if (!methods) {
+    return;
+  }
+
+  // Store original functions
+  sCloseFn      = methods->close;
+  sReadFn       = methods->read;
+  sWriteFn      = methods->write;
+  sFSyncFn      = methods->fsync;
+  sFileInfoFn   = methods->fileInfo;
+  sFileInfo64Fn = methods->fileInfo64;
+
+  // Overwrite with our interposed functions
+  methods->close      = &interposedClose;
+  methods->read       = &interposedRead;
+  methods->write      = &interposedWrite;
+  methods->fsync      = &interposedFSync;
+  methods->fileInfo   = &interposedFileInfo;
+  methods->fileInfo64 = &interposedFileInfo64;
+}
+
+void
+ClearNSPRIOInterposing()
+{
+  // If we have already cleared IO interposing, or not initialized it this is
+  // actually bad.
+  MOZ_ASSERT(sCloseFn && sReadFn && sWriteFn && sFSyncFn && sFileInfoFn &&
+             sFileInfo64Fn);
+
+  // Get IO methods from NSPR and const cast the structure so we can modify it.
+  PRIOMethods* methods = const_cast<PRIOMethods*>(PR_GetFileMethods());
+
+  // Something is badly wrong if we don't get IO methods... However, we don't
+  // want to crash over that in non-debug builds. This is unlikely to happen
+  // so an assert is enough, no need to report it to the caller.
+  MOZ_ASSERT(methods);
+  if (!methods) {
+    return;
+  }
+
+  // Restore original functions
+  methods->close      = sCloseFn;
+  methods->read       = sReadFn;
+  methods->write      = sWriteFn;
+  methods->fsync      = sFSyncFn;
+  methods->fileInfo   = sFileInfoFn;
+  methods->fileInfo64 = sFileInfo64Fn;
+
+  // Forget about original functions
+  sCloseFn      = nullptr;
+  sReadFn       = nullptr;
+  sWriteFn      = nullptr;
+  sFSyncFn      = nullptr;
+  sFileInfoFn   = nullptr;
+  sFileInfo64Fn = nullptr;
+}
+
+} // namespace mozilla
+
diff --git a/xpcom/build/NSPRInterposer.h b/xpcom/build/NSPRInterposer.h
new file mode 100644
index 000000000..2b8715077
--- /dev/null
+++ b/xpcom/build/NSPRInterposer.h
@@ -0,0 +1,28 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef NSPRINTERPOSER_H_
+#define NSPRINTERPOSER_H_
+
+namespace mozilla {
+
+/**
+ * Initialize IO interposing for NSPR. This will report NSPR read, writes and
+ * fsyncs to the IOInterposerObserver. It is only safe to call this from the
+ * main-thread when no other threads are running.
+ */
+void InitNSPRIOInterposing();
+
+/**
+ * Removes interception of NSPR IO methods as setup by InitNSPRIOInterposing.
+ * Note, that it is only safe to call this on the main-thread when all other
+ * threads have stopped. Which is typically the case at shutdown.
+ */
+void ClearNSPRIOInterposing();
+
+} // namespace mozilla
+
+#endif // NSPRINTERPOSER_H_
diff --git a/xpcom/build/Omnijar.cpp b/xpcom/build/Omnijar.cpp
new file mode 100644
index 000000000..e1a8a1e5b
--- /dev/null
+++ b/xpcom/build/Omnijar.cpp
@@ -0,0 +1,188 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "Omnijar.h"
+
+#include "nsDirectoryService.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsIFile.h"
+#include "nsZipArchive.h"
+#include "nsNetUtil.h"
+
+namespace mozilla {
+
+StaticRefPtr<nsIFile> Omnijar::sPath[2];
+StaticRefPtr<nsZipArchive> Omnijar::sReader[2];
+StaticRefPtr<nsZipArchive> Omnijar::sOuterReader[2];
+bool Omnijar::sInitialized = false;
+bool Omnijar::sIsUnified = false;
+
+static const char* sProp[2] = {
+  NS_GRE_DIR, NS_XPCOM_CURRENT_PROCESS_DIR
+};
+
+#define SPROP(Type) ((Type == mozilla::Omnijar::GRE) ? sProp[GRE] : sProp[APP])
+
+void
+Omnijar::CleanUpOne(Type aType)
+{
+  if (sReader[aType]) {
+    sReader[aType]->CloseArchive();
+    sReader[aType] = nullptr;
+  }
+  if (sOuterReader[aType]) {
+    sOuterReader[aType]->CloseArchive();
+    sOuterReader[aType] = nullptr;
+  }
+  sPath[aType] = nullptr;
+}
+
+void
+Omnijar::InitOne(nsIFile* aPath, Type aType)
+{
+  nsCOMPtr<nsIFile> file;
+  if (aPath) {
+    file = aPath;
+  } else {
+    nsCOMPtr<nsIFile> dir;
+    nsDirectoryService::gService->Get(SPROP(aType), NS_GET_IID(nsIFile),
+                                      getter_AddRefs(dir));
+    NS_NAMED_LITERAL_CSTRING(kOmnijarName, NS_STRINGIFY(OMNIJAR_NAME));
+    if (NS_FAILED(dir->Clone(getter_AddRefs(file))) ||
+        NS_FAILED(file->AppendNative(kOmnijarName))) {
+      return;
+    }
+  }
+  bool isFile;
+  if (NS_FAILED(file->IsFile(&isFile)) || !isFile) {
+    // If we're not using an omni.jar for GRE, and we don't have an
+    // omni.jar for APP, check if both directories are the same.
+    if ((aType == APP) && (!sPath[GRE])) {
+      nsCOMPtr<nsIFile> greDir, appDir;
+      bool equals;
+      nsDirectoryService::gService->Get(sProp[GRE], NS_GET_IID(nsIFile),
+                                        getter_AddRefs(greDir));
+      nsDirectoryService::gService->Get(sProp[APP], NS_GET_IID(nsIFile),
+                                        getter_AddRefs(appDir));
+      if (NS_SUCCEEDED(greDir->Equals(appDir, &equals)) && equals) {
+        sIsUnified = true;
+      }
+    }
+    return;
+  }
+
+  bool equals;
+  if ((aType == APP) && (sPath[GRE]) &&
+      NS_SUCCEEDED(sPath[GRE]->Equals(file, &equals)) && equals) {
+    // If we're using omni.jar on both GRE and APP and their path
+    // is the same, we're in the unified case.
+    sIsUnified = true;
+    return;
+  }
+
+  RefPtr<nsZipArchive> zipReader = new nsZipArchive();
+  if (NS_FAILED(zipReader->OpenArchive(file))) {
+    return;
+  }
+
+  RefPtr<nsZipArchive> outerReader;
+  RefPtr<nsZipHandle> handle;
+  if (NS_SUCCEEDED(nsZipHandle::Init(zipReader, NS_STRINGIFY(OMNIJAR_NAME),
+                                     getter_AddRefs(handle)))) {
+    outerReader = zipReader;
+    zipReader = new nsZipArchive();
+    if (NS_FAILED(zipReader->OpenArchive(handle))) {
+      return;
+    }
+  }
+
+  CleanUpOne(aType);
+  sReader[aType] = zipReader;
+  sOuterReader[aType] = outerReader;
+  sPath[aType] = file;
+}
+
+void
+Omnijar::Init(nsIFile* aGrePath, nsIFile* aAppPath)
+{
+  InitOne(aGrePath, GRE);
+  InitOne(aAppPath, APP);
+  sInitialized = true;
+}
+
+void
+Omnijar::CleanUp()
+{
+  CleanUpOne(GRE);
+  CleanUpOne(APP);
+  sInitialized = false;
+}
+
+already_AddRefed<nsZipArchive>
+Omnijar::GetReader(nsIFile* aPath)
+{
+  MOZ_ASSERT(IsInitialized(), "Omnijar not initialized");
+
+  bool equals;
+  nsresult rv;
+
+  if (sPath[GRE]) {
+    rv = sPath[GRE]->Equals(aPath, &equals);
+    if (NS_SUCCEEDED(rv) && equals) {
+      return IsNested(GRE) ? GetOuterReader(GRE) : GetReader(GRE);
+    }
+  }
+  if (sPath[APP]) {
+    rv = sPath[APP]->Equals(aPath, &equals);
+    if (NS_SUCCEEDED(rv) && equals) {
+      return IsNested(APP) ? GetOuterReader(APP) : GetReader(APP);
+    }
+  }
+  return nullptr;
+}
+
+nsresult
+Omnijar::GetURIString(Type aType, nsACString& aResult)
+{
+  MOZ_ASSERT(IsInitialized(), "Omnijar not initialized");
+
+  aResult.Truncate();
+
+  // Return an empty string for APP in the unified case.
+  if ((aType == APP) && sIsUnified) {
+    return NS_OK;
+  }
+
+  nsAutoCString omniJarSpec;
+  if (sPath[aType]) {
+    nsresult rv = NS_GetURLSpecFromActualFile(sPath[aType], omniJarSpec);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    aResult = "jar:";
+    if (IsNested(aType)) {
+      aResult += "jar:";
+    }
+    aResult += omniJarSpec;
+    aResult += "!";
+    if (IsNested(aType)) {
+      aResult += "/" NS_STRINGIFY(OMNIJAR_NAME) "!";
+    }
+  } else {
+    nsCOMPtr<nsIFile> dir;
+    nsDirectoryService::gService->Get(SPROP(aType), NS_GET_IID(nsIFile),
+                                      getter_AddRefs(dir));
+    nsresult rv = NS_GetURLSpecFromActualFile(dir, aResult);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+  aResult += "/";
+  return NS_OK;
+}
+
+} /* namespace mozilla */
diff --git a/xpcom/build/Omnijar.h b/xpcom/build/Omnijar.h
new file mode 100644
index 000000000..35a208bae
--- /dev/null
+++ b/xpcom/build/Omnijar.h
@@ -0,0 +1,160 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_Omnijar_h
+#define mozilla_Omnijar_h
+
+#include "nscore.h"
+#include "nsCOMPtr.h"
+#include "nsString.h"
+#include "nsIFile.h"
+#include "nsZipArchive.h"
+
+#include "mozilla/StaticPtr.h"
+
+namespace mozilla {
+
+class Omnijar
+{
+private:
+  /**
+   * Store an nsIFile for an omni.jar. We can store two paths here, one
+   * for GRE (corresponding to resource://gre/) and one for APP
+   * (corresponding to resource:/// and resource://app/), but only
+   * store one when both point to the same location (unified).
+   */
+  static StaticRefPtr<nsIFile> sPath[2];
+
+  /**
+   * Cached nsZipArchives for the corresponding sPath
+   */
+  static StaticRefPtr<nsZipArchive> sReader[2];
+
+  /**
+   * Cached nsZipArchives for the outer jar, when using nested jars.
+   * Otherwise nullptr.
+   */
+  static StaticRefPtr<nsZipArchive> sOuterReader[2];
+
+  /**
+   * Has Omnijar::Init() been called?
+   */
+  static bool sInitialized;
+
+  /**
+   * Is using unified GRE/APP jar?
+   */
+  static bool sIsUnified;
+
+public:
+  enum Type
+  {
+    GRE = 0,
+    APP = 1
+  };
+
+private:
+  /**
+   * Returns whether we are using nested jars.
+   */
+  static inline bool IsNested(Type aType)
+  {
+    MOZ_ASSERT(IsInitialized(), "Omnijar not initialized");
+    return !!sOuterReader[aType];
+  }
+
+  /**
+   * Returns a nsZipArchive pointer for the outer jar file when using nested
+   * jars. Returns nullptr in the same cases GetPath() would, or if not using
+   * nested jars.
+   */
+  static inline already_AddRefed<nsZipArchive> GetOuterReader(Type aType)
+  {
+    MOZ_ASSERT(IsInitialized(), "Omnijar not initialized");
+    RefPtr<nsZipArchive> reader = sOuterReader[aType].get();
+    return reader.forget();
+  }
+
+public:
+  /**
+   * Returns whether SetBase has been called at least once with
+   * a valid nsIFile
+   */
+  static inline bool IsInitialized() { return sInitialized; }
+
+  /**
+   * Initializes the Omnijar API with the given directory or file for GRE and
+   * APP. Each of the paths given can be:
+   * - a file path, pointing to the omnijar file,
+   * - a directory path, pointing to a directory containing an "omni.jar" file,
+   * - nullptr for autodetection of an "omni.jar" file.
+   */
+  static void Init(nsIFile* aGrePath = nullptr, nsIFile* aAppPath = nullptr);
+
+  /**
+   * Cleans up the Omnijar API
+   */
+  static void CleanUp();
+
+  /**
+   * Returns an nsIFile pointing to the omni.jar file for GRE or APP.
+   * Returns nullptr when there is no corresponding omni.jar.
+   * Also returns nullptr for APP in the unified case.
+   */
+  static inline already_AddRefed<nsIFile> GetPath(Type aType)
+  {
+    MOZ_ASSERT(IsInitialized(), "Omnijar not initialized");
+    nsCOMPtr<nsIFile> path = sPath[aType].get();
+    return path.forget();
+  }
+
+  /**
+   * Returns whether GRE or APP use an omni.jar. Returns PR_False for
+   * APP when using an omni.jar in the unified case.
+   */
+  static inline bool HasOmnijar(Type aType)
+  {
+    MOZ_ASSERT(IsInitialized(), "Omnijar not initialized");
+    return !!sPath[aType];
+  }
+
+  /**
+   * Returns a nsZipArchive pointer for the omni.jar file for GRE or
+   * APP. Returns nullptr in the same cases GetPath() would.
+   */
+  static inline already_AddRefed<nsZipArchive> GetReader(Type aType)
+  {
+    MOZ_ASSERT(IsInitialized(), "Omnijar not initialized");
+    RefPtr<nsZipArchive> reader = sReader[aType].get();
+    return reader.forget();
+  }
+
+  /**
+   * Returns a nsZipArchive pointer for the given path IAOI the given
+   * path is the omni.jar for either GRE or APP.
+   */
+  static already_AddRefed<nsZipArchive> GetReader(nsIFile* aPath);
+
+  /**
+   * Returns the URI string corresponding to the omni.jar or directory
+   * for GRE or APP. i.e. jar:/path/to/omni.jar!/ for omni.jar and
+   * /path/to/base/dir/ otherwise. Returns an empty string for APP in
+   * the unified case.
+   * The returned URI is guaranteed to end with a slash.
+   */
+  static nsresult GetURIString(Type aType, nsACString& aResult);
+
+private:
+  /**
+   * Used internally, respectively by Init() and CleanUp()
+   */
+  static void InitOne(nsIFile* aPath, Type aType);
+  static void CleanUpOne(Type aType);
+}; /* class Omnijar */
+
+} /* namespace mozilla */
+
+#endif /* mozilla_Omnijar_h */
diff --git a/xpcom/build/PoisonIOInterposer.h b/xpcom/build/PoisonIOInterposer.h
new file mode 100644
index 000000000..4a4d1426d
--- /dev/null
+++ b/xpcom/build/PoisonIOInterposer.h
@@ -0,0 +1,91 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_PoisonIOInterposer_h
+#define mozilla_PoisonIOInterposer_h
+
+#include "mozilla/Types.h"
+#include <stdio.h>
+
+MOZ_BEGIN_EXTERN_C
+
+/** Register file handle to be ignored by poisoning IO interposer. This function
+ * and the corresponding UnRegister function are necessary for exchange of handles
+ * between binaries not using the same CRT on Windows (which happens when one of
+ * them links the static CRT). In such cases, giving file descriptors or FILEs
+ * doesn't work because _get_osfhandle fails with "invalid parameter". */
+void MozillaRegisterDebugHandle(intptr_t aHandle);
+
+/** Register file descriptor to be ignored by poisoning IO interposer */
+void MozillaRegisterDebugFD(int aFd);
+
+/** Register file to be ignored by poisoning IO interposer */
+void MozillaRegisterDebugFILE(FILE* aFile);
+
+/** Unregister file handle from being ignored by poisoning IO interposer */
+void MozillaUnRegisterDebugHandle(intptr_t aHandle);
+
+/** Unregister file descriptor from being ignored by poisoning IO interposer */
+void MozillaUnRegisterDebugFD(int aFd);
+
+/** Unregister file from being ignored by poisoning IO interposer */
+void MozillaUnRegisterDebugFILE(FILE* aFile);
+
+MOZ_END_EXTERN_C
+
+#if defined(XP_WIN) || defined(XP_MACOSX)
+
+#ifdef __cplusplus
+namespace mozilla {
+
+/**
+ * Check if a file is registered as a debug file.
+ */
+bool IsDebugFile(intptr_t aFileID);
+
+/**
+ * Initialize IO poisoning, this is only safe to do on the main-thread when no
+ * other threads are running.
+ *
+ * Please, note that this probably has performance implications as all
+ */
+void InitPoisonIOInterposer();
+
+#ifdef XP_MACOSX
+/**
+ * Check that writes are dirty before reporting I/O (Mac OS X only)
+ * This is necessary for late-write checks on Mac OS X, but reading the buffer
+ * from file to see if we're writing dirty bits is expensive, so we don't want
+ * to do this for everything else that uses
+ */
+void OnlyReportDirtyWrites();
+#endif /* XP_MACOSX */
+
+/**
+ * Clear IO poisoning, this is only safe to do on the main-thread when no other
+ * threads are running.
+ */
+void ClearPoisonIOInterposer();
+
+} // namespace mozilla
+#endif /* __cplusplus */
+
+#else /* XP_WIN || XP_MACOSX */
+
+#ifdef __cplusplus
+namespace mozilla {
+inline bool IsDebugFile(intptr_t aFileID) { return true; }
+inline void InitPoisonIOInterposer() {}
+inline void ClearPoisonIOInterposer() {}
+#ifdef XP_MACOSX
+inline void OnlyReportDirtyWrites() {}
+#endif /* XP_MACOSX */
+} // namespace mozilla
+#endif /* __cplusplus */
+
+#endif /* XP_WIN || XP_MACOSX */
+
+#endif // mozilla_PoisonIOInterposer_h
diff --git a/xpcom/build/PoisonIOInterposerBase.cpp b/xpcom/build/PoisonIOInterposerBase.cpp
new file mode 100644
index 000000000..0e5754392
--- /dev/null
+++ b/xpcom/build/PoisonIOInterposerBase.cpp
@@ -0,0 +1,291 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Mutex.h"
+#include "mozilla/Scoped.h"
+#include "mozilla/UniquePtr.h"
+
+#include <algorithm>
+
+#include "PoisonIOInterposer.h"
+
+#ifdef MOZ_REPLACE_MALLOC
+#include "replace_malloc_bridge.h"
+#endif
+
+// Auxiliary method to convert file descriptors to ids
+#if defined(XP_WIN32)
+#include <io.h>
+inline intptr_t
+FileDescriptorToHandle(int aFd)
+{
+  return _get_osfhandle(aFd);
+}
+#else
+inline intptr_t
+FileDescriptorToHandle(int aFd)
+{
+  return aFd;
+}
+#endif /* if not XP_WIN32 */
+
+using namespace mozilla;
+
+namespace {
+struct DebugFilesAutoLockTraits
+{
+  typedef PRLock* type;
+  typedef const PRLock* const_type;
+  static const_type empty() { return nullptr; }
+  static void release(type aL) { PR_Unlock(aL); }
+};
+
+class DebugFilesAutoLock : public Scoped<DebugFilesAutoLockTraits>
+{
+  static PRLock* Lock;
+public:
+  static void Clear();
+  static PRLock* getDebugFileIDsLock()
+  {
+    // On windows this static is not thread safe, but we know that the first
+    // call is from
+    // * An early registration of a debug FD or
+    // * The call to InitWritePoisoning.
+    // Since the early debug FDs are logs created early in the main thread
+    // and no writes are trapped before InitWritePoisoning, we are safe.
+    if (!Lock) {
+      Lock = PR_NewLock();
+    }
+
+    // We have to use something lower level than a mutex. If we don't, we
+    // can get recursive in here when called from logging a call to free.
+    return Lock;
+  }
+
+  DebugFilesAutoLock()
+    : Scoped<DebugFilesAutoLockTraits>(getDebugFileIDsLock())
+  {
+    PR_Lock(get());
+  }
+};
+
+PRLock* DebugFilesAutoLock::Lock;
+void
+DebugFilesAutoLock::Clear()
+{
+  MOZ_ASSERT(Lock != nullptr);
+  Lock = nullptr;
+}
+
+// The ChunkedList<T> class implements, at the high level, a non-iterable
+// list of instances of T. Its goal is to be somehow minimalist for the
+// use case of storing the debug files handles here, with the property of
+// not requiring a lock to look up whether it contains a specific value.
+// It is also chunked in blocks of chunk_size bytes so that its
+// initialization doesn't require a memory allocation, while keeping the
+// possibility to increase its size as necessary. Note that chunks are
+// never deallocated (except in the destructor).
+// All operations are essentially O(N) but N is not expected to be large
+// enough to matter.
+template <typename T, size_t chunk_size=64>
+class ChunkedList {
+  struct ListChunk {
+    static const size_t kLength = \
+      (chunk_size - sizeof(ListChunk*)) / sizeof(mozilla::Atomic<T>);
+
+    mozilla::Atomic<T> mElements[kLength];
+    mozilla::UniquePtr<ListChunk> mNext;
+
+    ListChunk() : mNext(nullptr) {}
+  };
+
+  ListChunk mList;
+  mozilla::Atomic<size_t> mLength;
+
+public:
+  ChunkedList() : mLength(0) {}
+
+  ~ChunkedList() {
+    // There can be writes happening after this destructor runs, so keep
+    // the list contents and don't reset mLength. But if there are more
+    // elements left than the first chunk can hold, then all hell breaks
+    // loose for any write that would happen after that because any extra
+    // chunk would be deallocated, so just crash in that case.
+    MOZ_RELEASE_ASSERT(mLength <= ListChunk::kLength);
+  }
+
+  // Add an element at the end of the last chunk of the list. Create a new
+  // chunk if there is not enough room.
+  // This is not thread-safe with another thread calling Add or Remove.
+  void Add(T aValue)
+  {
+    ListChunk *list = &mList;
+    size_t position = mLength;
+    for (; position >= ListChunk::kLength; position -= ListChunk::kLength) {
+      if (!list->mNext) {
+        list->mNext.reset(new ListChunk());
+      }
+      list = list->mNext.get();
+    }
+    // Use an order of operations that ensures any racing Contains call
+    // can't be hurt.
+    list->mElements[position] = aValue;
+    mLength++;
+  }
+
+  // Remove an element from the list by replacing it with the last element
+  // of the list, and then shrinking the list.
+  // This is not thread-safe with another thread calling Add or Remove.
+  void Remove(T aValue)
+  {
+    if (!mLength) {
+      return;
+    }
+    ListChunk *list = &mList;
+    size_t last = mLength - 1;
+    do {
+      size_t position = 0;
+      // Look for an element matching the given value.
+      for (; position < ListChunk::kLength; position++) {
+        if (aValue == list->mElements[position]) {
+          ListChunk *last_list = list;
+          // Look for the last element in the list, starting from where we are
+          // instead of starting over.
+          for (; last >= ListChunk::kLength; last -= ListChunk::kLength) {
+            last_list = last_list->mNext.get();
+          }
+          // Use an order of operations that ensures any racing Contains call
+          // can't be hurt.
+          T value = last_list->mElements[last];
+          list->mElements[position] = value;
+          mLength--;
+          return;
+        }
+      }
+      last -= ListChunk::kLength;
+      list = list->mNext.get();
+    } while (list);
+  }
+
+  // Returns whether the list contains the given value. It is meant to be safe
+  // to use without locking, with the tradeoff of being not entirely accurate
+  // if another thread adds or removes an element while this function runs.
+  bool Contains(T aValue)
+  {
+    ListChunk *list = &mList;
+    // Fix the range of the lookup to whatever the list length is when the
+    // function is called.
+    size_t length = mLength;
+    do {
+      size_t list_length = ListChunk::kLength;
+      list_length = std::min(list_length, length);
+      for (size_t position = 0; position < list_length; position++) {
+        if (aValue == list->mElements[position]) {
+          return true;
+        }
+      }
+      length -= ListChunk::kLength;
+      list = list->mNext.get();
+    } while (list);
+
+    return false;
+  }
+};
+
+typedef ChunkedList<intptr_t> FdList;
+
+// Return a list used to hold the IDs of the current debug files. On unix
+// an ID is a file descriptor. On Windows it is a file HANDLE.
+FdList&
+getDebugFileIDs()
+{
+  static FdList DebugFileIDs;
+  return DebugFileIDs;
+}
+
+
+} // namespace
+
+namespace mozilla {
+
+// Auxiliary Method to test if a file descriptor is registered to be ignored
+// by the poisoning IO interposer
+bool
+IsDebugFile(intptr_t aFileID)
+{
+  return getDebugFileIDs().Contains(aFileID);
+}
+
+} // namespace mozilla
+
+extern "C" {
+
+void
+MozillaRegisterDebugHandle(intptr_t aHandle)
+{
+  DebugFilesAutoLock lockedScope;
+  FdList& DebugFileIDs = getDebugFileIDs();
+  MOZ_ASSERT(!DebugFileIDs.Contains(aHandle));
+  DebugFileIDs.Add(aHandle);
+}
+
+void
+MozillaRegisterDebugFD(int aFd)
+{
+  MozillaRegisterDebugHandle(FileDescriptorToHandle(aFd));
+}
+
+void
+MozillaRegisterDebugFILE(FILE* aFile)
+{
+  int fd = fileno(aFile);
+  if (fd == 1 || fd == 2) {
+    return;
+  }
+  MozillaRegisterDebugFD(fd);
+}
+
+void
+MozillaUnRegisterDebugHandle(intptr_t aHandle)
+{
+  DebugFilesAutoLock lockedScope;
+  FdList& DebugFileIDs = getDebugFileIDs();
+  MOZ_ASSERT(DebugFileIDs.Contains(aHandle));
+  DebugFileIDs.Remove(aHandle);
+}
+
+void
+MozillaUnRegisterDebugFD(int aFd)
+{
+  MozillaUnRegisterDebugHandle(FileDescriptorToHandle(aFd));
+}
+
+void
+MozillaUnRegisterDebugFILE(FILE* aFile)
+{
+  int fd = fileno(aFile);
+  if (fd == 1 || fd == 2) {
+    return;
+  }
+  fflush(aFile);
+  MozillaUnRegisterDebugFD(fd);
+}
+
+}  // extern "C"
+
+#ifdef MOZ_REPLACE_MALLOC
+void
+DebugFdRegistry::RegisterHandle(intptr_t aHandle)
+{
+  MozillaRegisterDebugHandle(aHandle);
+}
+
+void
+DebugFdRegistry::UnRegisterHandle(intptr_t aHandle)
+{
+  MozillaUnRegisterDebugHandle(aHandle);
+}
+#endif
diff --git a/xpcom/build/PoisonIOInterposerMac.cpp b/xpcom/build/PoisonIOInterposerMac.cpp
new file mode 100644
index 000000000..966269495
--- /dev/null
+++ b/xpcom/build/PoisonIOInterposerMac.cpp
@@ -0,0 +1,386 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "PoisonIOInterposer.h"
+#include "mach_override.h"
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/IOInterposer.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/ProcessedStack.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/UniquePtrExtensions.h"
+#include "nsPrintfCString.h"
+#include "mozilla/StackWalk.h"
+#include "nsTraceRefcnt.h"
+#include "plstr.h"
+#include "prio.h"
+
+#include <algorithm>
+#include <vector>
+
+#include <sys/param.h>
+#include <sys/stat.h>
+#include <sys/socket.h>
+#include <sys/uio.h>
+#include <aio.h>
+#include <dlfcn.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#ifdef MOZ_REPLACE_MALLOC
+#include "replace_malloc_bridge.h"
+#endif
+
+namespace {
+
+using namespace mozilla;
+
+// Bit tracking if poisoned writes are enabled
+static bool sIsEnabled = false;
+
+// Check if writes are dirty before reporting IO
+static bool sOnlyReportDirtyWrites = false;
+
+// Routines for write validation
+bool IsValidWrite(int aFd, const void* aWbuf, size_t aCount);
+bool IsIPCWrite(int aFd, const struct stat& aBuf);
+
+/******************************** IO AutoTimer ********************************/
+
+/**
+ * RAII class for timing the duration of an I/O call and reporting the result
+ * to the IOInterposeObserver API.
+ */
+class MacIOAutoObservation : public IOInterposeObserver::Observation
+{
+public:
+  MacIOAutoObservation(IOInterposeObserver::Operation aOp, int aFd)
+    : IOInterposeObserver::Observation(aOp, sReference, sIsEnabled &&
+                                       !IsDebugFile(aFd))
+    , mFd(aFd)
+    , mHasQueriedFilename(false)
+    , mFilename(nullptr)
+  {
+  }
+
+  MacIOAutoObservation(IOInterposeObserver::Operation aOp, int aFd,
+                       const void* aBuf, size_t aCount)
+    : IOInterposeObserver::Observation(aOp, sReference, sIsEnabled &&
+                                       !IsDebugFile(aFd) &&
+                                       IsValidWrite(aFd, aBuf, aCount))
+    , mFd(aFd)
+    , mHasQueriedFilename(false)
+    , mFilename(nullptr)
+  {
+  }
+
+  // Custom implementation of IOInterposeObserver::Observation::Filename
+  const char16_t* Filename() override;
+
+  ~MacIOAutoObservation()
+  {
+    Report();
+    if (mFilename) {
+      free(mFilename);
+      mFilename = nullptr;
+    }
+  }
+
+private:
+  int                 mFd;
+  bool                mHasQueriedFilename;
+  char16_t*           mFilename;
+  static const char*  sReference;
+};
+
+const char* MacIOAutoObservation::sReference = "PoisonIOInterposer";
+
+// Get filename for this observation
+const char16_t*
+MacIOAutoObservation::Filename()
+{
+  // If mHasQueriedFilename is true, then we already have it
+  if (mHasQueriedFilename) {
+    return mFilename;
+  }
+  char filename[MAXPATHLEN];
+  if (fcntl(mFd, F_GETPATH, filename) != -1) {
+    mFilename = UTF8ToNewUnicode(nsDependentCString(filename));
+  } else {
+    mFilename = nullptr;
+  }
+  mHasQueriedFilename = true;
+
+  // Return filename
+  return mFilename;
+}
+
+/****************************** Write Validation ******************************/
+
+// We want to detect "actual" writes, not IPC. Some IPC mechanisms are
+// implemented with file descriptors, so filter them out.
+bool
+IsIPCWrite(int aFd, const struct stat& aBuf)
+{
+  if ((aBuf.st_mode & S_IFMT) == S_IFIFO) {
+    return true;
+  }
+
+  if ((aBuf.st_mode & S_IFMT) != S_IFSOCK) {
+    return false;
+  }
+
+  sockaddr_storage address;
+  socklen_t len = sizeof(address);
+  if (getsockname(aFd, (sockaddr*)&address, &len) != 0) {
+    return true; // Ignore the aFd if we can't find what it is.
+  }
+
+  return address.ss_family == AF_UNIX;
+}
+
+// We want to report actual disk IO not things that don't move bits on the disk
+bool
+IsValidWrite(int aFd, const void* aWbuf, size_t aCount)
+{
+  // Ignore writes of zero bytes, Firefox does some during shutdown.
+  if (aCount == 0) {
+    return false;
+  }
+
+  {
+    struct stat buf;
+    int rv = fstat(aFd, &buf);
+    if (rv != 0) {
+      return true;
+    }
+
+    if (IsIPCWrite(aFd, buf)) {
+      return false;
+    }
+  }
+
+  // For writev we pass a nullptr aWbuf. We should only get here from
+  // dbm, and it uses write, so assert that we have aWbuf.
+  if (!aWbuf) {
+    return true;
+  }
+
+  // Break, here if we're allowed to report non-dirty writes
+  if (!sOnlyReportDirtyWrites) {
+    return true;
+  }
+
+  // As a really bad hack, accept writes that don't change the on disk
+  // content. This is needed because dbm doesn't keep track of dirty bits
+  // and can end up writing the same data to disk twice. Once when the
+  // user (nss) asks it to sync and once when closing the database.
+  auto wbuf2 = MakeUniqueFallible<char[]>(aCount);
+  if (!wbuf2) {
+    return true;
+  }
+  off_t pos = lseek(aFd, 0, SEEK_CUR);
+  if (pos == -1) {
+    return true;
+  }
+  ssize_t r = read(aFd, wbuf2.get(), aCount);
+  if (r < 0 || (size_t)r != aCount) {
+    return true;
+  }
+  int cmp = memcmp(aWbuf, wbuf2.get(), aCount);
+  if (cmp != 0) {
+    return true;
+  }
+  off_t pos2 = lseek(aFd, pos, SEEK_SET);
+  if (pos2 != pos) {
+    return true;
+  }
+
+  // Otherwise this is not a valid write
+  return false;
+}
+
+/*************************** Function Interception  ***************************/
+
+/** Structure for declaration of function override */
+struct FuncData
+{
+  const char* Name;      // Name of the function for the ones we use dlsym
+  const void* Wrapper;   // The function that we will replace 'Function' with
+  void* Function;        // The function that will be replaced with 'Wrapper'
+  void* Buffer;          // Will point to the jump buffer that lets us call
+                         // 'Function' after it has been replaced.
+};
+
+// Wrap aio_write. We have not seen it before, so just assert/report it.
+typedef ssize_t (*aio_write_t)(struct aiocb* aAioCbp);
+ssize_t wrap_aio_write(struct aiocb* aAioCbp);
+FuncData aio_write_data = { 0, (void*)wrap_aio_write, (void*)aio_write };
+ssize_t
+wrap_aio_write(struct aiocb* aAioCbp)
+{
+  MacIOAutoObservation timer(IOInterposeObserver::OpWrite,
+                             aAioCbp->aio_fildes);
+
+  aio_write_t old_write = (aio_write_t)aio_write_data.Buffer;
+  return old_write(aAioCbp);
+}
+
+// Wrap pwrite-like functions.
+// We have not seen them before, so just assert/report it.
+typedef ssize_t (*pwrite_t)(int aFd, const void* buf, size_t aNumBytes,
+                            off_t aOffset);
+template<FuncData& foo>
+ssize_t
+wrap_pwrite_temp(int aFd, const void* aBuf, size_t aNumBytes, off_t aOffset)
+{
+  MacIOAutoObservation timer(IOInterposeObserver::OpWrite, aFd);
+  pwrite_t old_write = (pwrite_t)foo.Buffer;
+  return old_write(aFd, aBuf, aNumBytes, aOffset);
+}
+
+// Define a FuncData for a pwrite-like functions.
+#define DEFINE_PWRITE_DATA(X, NAME)                                        \
+FuncData X ## _data = { NAME, (void*) wrap_pwrite_temp<X ## _data> };      \
+
+// This exists everywhere.
+DEFINE_PWRITE_DATA(pwrite, "pwrite")
+// These exist on 32 bit OS X
+DEFINE_PWRITE_DATA(pwrite_NOCANCEL_UNIX2003, "pwrite$NOCANCEL$UNIX2003");
+DEFINE_PWRITE_DATA(pwrite_UNIX2003, "pwrite$UNIX2003");
+// This exists on 64 bit OS X
+DEFINE_PWRITE_DATA(pwrite_NOCANCEL, "pwrite$NOCANCEL");
+
+
+typedef ssize_t (*writev_t)(int aFd, const struct iovec* aIov, int aIovCount);
+template<FuncData& foo>
+ssize_t
+wrap_writev_temp(int aFd, const struct iovec* aIov, int aIovCount)
+{
+  MacIOAutoObservation timer(IOInterposeObserver::OpWrite, aFd, nullptr,
+                             aIovCount);
+  writev_t old_write = (writev_t)foo.Buffer;
+  return old_write(aFd, aIov, aIovCount);
+}
+
+// Define a FuncData for a writev-like functions.
+#define DEFINE_WRITEV_DATA(X, NAME)                                   \
+FuncData X ## _data = { NAME, (void*) wrap_writev_temp<X ## _data> }; \
+
+// This exists everywhere.
+DEFINE_WRITEV_DATA(writev, "writev");
+// These exist on 32 bit OS X
+DEFINE_WRITEV_DATA(writev_NOCANCEL_UNIX2003, "writev$NOCANCEL$UNIX2003");
+DEFINE_WRITEV_DATA(writev_UNIX2003, "writev$UNIX2003");
+// This exists on 64 bit OS X
+DEFINE_WRITEV_DATA(writev_NOCANCEL, "writev$NOCANCEL");
+
+typedef ssize_t (*write_t)(int aFd, const void* aBuf, size_t aCount);
+template<FuncData& foo>
+ssize_t
+wrap_write_temp(int aFd, const void* aBuf, size_t aCount)
+{
+  MacIOAutoObservation timer(IOInterposeObserver::OpWrite, aFd, aBuf, aCount);
+  write_t old_write = (write_t)foo.Buffer;
+  return old_write(aFd, aBuf, aCount);
+}
+
+// Define a FuncData for a write-like functions.
+#define DEFINE_WRITE_DATA(X, NAME)                                   \
+FuncData X ## _data = { NAME, (void*) wrap_write_temp<X ## _data> }; \
+
+// This exists everywhere.
+DEFINE_WRITE_DATA(write, "write");
+// These exist on 32 bit OS X
+DEFINE_WRITE_DATA(write_NOCANCEL_UNIX2003, "write$NOCANCEL$UNIX2003");
+DEFINE_WRITE_DATA(write_UNIX2003, "write$UNIX2003");
+// This exists on 64 bit OS X
+DEFINE_WRITE_DATA(write_NOCANCEL, "write$NOCANCEL");
+
+FuncData* Functions[] = {
+  &aio_write_data,
+
+  &pwrite_data,
+  &pwrite_NOCANCEL_UNIX2003_data,
+  &pwrite_UNIX2003_data,
+  &pwrite_NOCANCEL_data,
+
+  &write_data,
+  &write_NOCANCEL_UNIX2003_data,
+  &write_UNIX2003_data,
+  &write_NOCANCEL_data,
+
+  &writev_data,
+  &writev_NOCANCEL_UNIX2003_data,
+  &writev_UNIX2003_data,
+  &writev_NOCANCEL_data
+};
+
+const int NumFunctions = ArrayLength(Functions);
+
+} // namespace
+
+/******************************** IO Poisoning ********************************/
+
+namespace mozilla {
+
+void
+InitPoisonIOInterposer()
+{
+  // Enable reporting from poisoned write methods
+  sIsEnabled = true;
+
+  // Make sure we only poison writes once!
+  static bool WritesArePoisoned = false;
+  if (WritesArePoisoned) {
+    return;
+  }
+  WritesArePoisoned = true;
+
+  // stdout and stderr are OK.
+  MozillaRegisterDebugFD(1);
+  MozillaRegisterDebugFD(2);
+
+#ifdef MOZ_REPLACE_MALLOC
+  // The contract with InitDebugFd is that the given registry can be used
+  // at any moment, so the instance needs to persist longer than the scope
+  // of this functions.
+  static DebugFdRegistry registry;
+  ReplaceMalloc::InitDebugFd(registry);
+#endif
+
+  for (int i = 0; i < NumFunctions; ++i) {
+    FuncData* d = Functions[i];
+    if (!d->Function) {
+      d->Function = dlsym(RTLD_DEFAULT, d->Name);
+    }
+    if (!d->Function) {
+      continue;
+    }
+    DebugOnly<mach_error_t> t = mach_override_ptr(d->Function, d->Wrapper,
+                                                  &d->Buffer);
+    MOZ_ASSERT(t == err_none);
+  }
+}
+
+void
+OnlyReportDirtyWrites()
+{
+  sOnlyReportDirtyWrites = true;
+}
+
+void
+ClearPoisonIOInterposer()
+{
+  // Not sure how or if we can unpoison the functions. Would be nice, but no
+  // worries we won't need to do this anyway.
+  sIsEnabled = false;
+}
+
+} // namespace mozilla
diff --git a/xpcom/build/PoisonIOInterposerStub.cpp b/xpcom/build/PoisonIOInterposerStub.cpp
new file mode 100644
index 000000000..1f3daa353
--- /dev/null
+++ b/xpcom/build/PoisonIOInterposerStub.cpp
@@ -0,0 +1,16 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdio.h>
+
+extern "C" {
+
+void MozillaRegisterDebugFD(int aFd) {}
+void MozillaRegisterDebugFILE(FILE* aFile) {}
+void MozillaUnRegisterDebugFD(int aFd) {}
+void MozillaUnRegisterDebugFILE(FILE* aFile) {}
+
+}  // extern "C"
diff --git a/xpcom/build/PoisonIOInterposerWin.cpp b/xpcom/build/PoisonIOInterposerWin.cpp
new file mode 100644
index 000000000..752743b34
--- /dev/null
+++ b/xpcom/build/PoisonIOInterposerWin.cpp
@@ -0,0 +1,501 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "PoisonIOInterposer.h"
+
+#include <algorithm>
+#include <stdio.h>
+#include <vector>
+
+#include <io.h>
+#include <windows.h>
+#include <winternl.h>
+
+#include "mozilla/Assertions.h"
+#include "mozilla/FileUtilsWin.h"
+#include "mozilla/IOInterposer.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/TimeStamp.h"
+#include "nsTArray.h"
+#include "nsWindowsDllInterceptor.h"
+#include "plstr.h"
+
+#ifdef MOZ_REPLACE_MALLOC
+#include "replace_malloc_bridge.h"
+#endif
+
+using namespace mozilla;
+
+namespace {
+
+// Keep track of poisoned state. Notice that there is no reason to lock access
+// to this variable as it's only changed in InitPoisonIOInterposer and
+// ClearPoisonIOInterposer which may only be called on the main-thread when no
+// other threads are running.
+static bool sIOPoisoned = false;
+
+/************************ Internal NT API Declarations ************************/
+
+/*
+ * Function pointer declaration for internal NT routine to create/open files.
+ * For documentation on the NtCreateFile routine, see MSDN.
+ */
+typedef NTSTATUS (NTAPI* NtCreateFileFn)(
+  PHANDLE aFileHandle,
+  ACCESS_MASK aDesiredAccess,
+  POBJECT_ATTRIBUTES aObjectAttributes,
+  PIO_STATUS_BLOCK aIoStatusBlock,
+  PLARGE_INTEGER aAllocationSize,
+  ULONG aFileAttributes,
+  ULONG aShareAccess,
+  ULONG aCreateDisposition,
+  ULONG aCreateOptions,
+  PVOID aEaBuffer,
+  ULONG aEaLength);
+
+/**
+ * Function pointer declaration for internal NT routine to read data from file.
+ * For documentation on the NtReadFile routine, see ZwReadFile on MSDN.
+ */
+typedef NTSTATUS (NTAPI* NtReadFileFn)(
+  HANDLE aFileHandle,
+  HANDLE aEvent,
+  PIO_APC_ROUTINE aApc,
+  PVOID aApcCtx,
+  PIO_STATUS_BLOCK aIoStatus,
+  PVOID aBuffer,
+  ULONG aLength,
+  PLARGE_INTEGER aOffset,
+  PULONG aKey);
+
+/**
+ * Function pointer declaration for internal NT routine to read data from file.
+ * No documentation exists, see wine sources for details.
+ */
+typedef NTSTATUS (NTAPI* NtReadFileScatterFn)(
+  HANDLE aFileHandle,
+  HANDLE aEvent,
+  PIO_APC_ROUTINE aApc,
+  PVOID aApcCtx,
+  PIO_STATUS_BLOCK aIoStatus,
+  FILE_SEGMENT_ELEMENT* aSegments,
+  ULONG aLength,
+  PLARGE_INTEGER aOffset,
+  PULONG aKey);
+
+/**
+ * Function pointer declaration for internal NT routine to write data to file.
+ * For documentation on the NtWriteFile routine, see ZwWriteFile on MSDN.
+ */
+typedef NTSTATUS (NTAPI* NtWriteFileFn)(
+  HANDLE aFileHandle,
+  HANDLE aEvent,
+  PIO_APC_ROUTINE aApc,
+  PVOID aApcCtx,
+  PIO_STATUS_BLOCK aIoStatus,
+  PVOID aBuffer,
+  ULONG aLength,
+  PLARGE_INTEGER aOffset,
+  PULONG aKey);
+
+/**
+ * Function pointer declaration for internal NT routine to write data to file.
+ * No documentation exists, see wine sources for details.
+ */
+typedef NTSTATUS (NTAPI* NtWriteFileGatherFn)(
+  HANDLE aFileHandle,
+  HANDLE aEvent,
+  PIO_APC_ROUTINE aApc,
+  PVOID aApcCtx,
+  PIO_STATUS_BLOCK aIoStatus,
+  FILE_SEGMENT_ELEMENT* aSegments,
+  ULONG aLength,
+  PLARGE_INTEGER aOffset,
+  PULONG aKey);
+
+/**
+ * Function pointer declaration for internal NT routine to flush to disk.
+ * For documentation on the NtFlushBuffersFile routine, see ZwFlushBuffersFile
+ * on MSDN.
+ */
+typedef NTSTATUS (NTAPI* NtFlushBuffersFileFn)(
+  HANDLE aFileHandle,
+  PIO_STATUS_BLOCK aIoStatusBlock);
+
+typedef struct _FILE_NETWORK_OPEN_INFORMATION* PFILE_NETWORK_OPEN_INFORMATION;
+/**
+ * Function pointer delaration for internal NT routine to query file attributes.
+ * (equivalent to stat)
+ */
+typedef NTSTATUS (NTAPI* NtQueryFullAttributesFileFn)(
+  POBJECT_ATTRIBUTES aObjectAttributes,
+  PFILE_NETWORK_OPEN_INFORMATION aFileInformation);
+
+/*************************** Auxiliary Declarations ***************************/
+
+/**
+ * RAII class for timing the duration of an I/O call and reporting the result
+ * to the IOInterposeObserver API.
+ */
+class WinIOAutoObservation : public IOInterposeObserver::Observation
+{
+public:
+  WinIOAutoObservation(IOInterposeObserver::Operation aOp,
+                       HANDLE aFileHandle, const LARGE_INTEGER* aOffset)
+    : IOInterposeObserver::Observation(
+        aOp, sReference, !IsDebugFile(reinterpret_cast<intptr_t>(aFileHandle)))
+    , mFileHandle(aFileHandle)
+    , mHasQueriedFilename(false)
+    , mFilename(nullptr)
+  {
+    if (mShouldReport) {
+      mOffset.QuadPart = aOffset ? aOffset->QuadPart : 0;
+    }
+  }
+
+  WinIOAutoObservation(IOInterposeObserver::Operation aOp, nsAString& aFilename)
+    : IOInterposeObserver::Observation(aOp, sReference)
+    , mFileHandle(nullptr)
+    , mHasQueriedFilename(false)
+    , mFilename(nullptr)
+  {
+    if (mShouldReport) {
+      nsAutoString dosPath;
+      if (NtPathToDosPath(aFilename, dosPath)) {
+        mFilename = ToNewUnicode(dosPath);
+        mHasQueriedFilename = true;
+      }
+      mOffset.QuadPart = 0;
+    }
+  }
+
+  // Custom implementation of IOInterposeObserver::Observation::Filename
+  const char16_t* Filename() override;
+
+  ~WinIOAutoObservation()
+  {
+    Report();
+    if (mFilename) {
+      MOZ_ASSERT(mHasQueriedFilename);
+      free(mFilename);
+      mFilename = nullptr;
+    }
+  }
+
+private:
+  HANDLE              mFileHandle;
+  LARGE_INTEGER       mOffset;
+  bool                mHasQueriedFilename;
+  char16_t*           mFilename;
+  static const char*  sReference;
+};
+
+const char* WinIOAutoObservation::sReference = "PoisonIOInterposer";
+
+// Get filename for this observation
+const char16_t*
+WinIOAutoObservation::Filename()
+{
+  // If mHasQueriedFilename is true, then filename is already stored in mFilename
+  if (mHasQueriedFilename) {
+    return mFilename;
+  }
+
+  nsAutoString utf16Filename;
+  if (HandleToFilename(mFileHandle, mOffset, utf16Filename)) {
+    // Heap allocate with leakable memory
+    mFilename = ToNewUnicode(utf16Filename);
+  }
+  mHasQueriedFilename = true;
+
+  // Return filename
+  return mFilename;
+}
+
+/*************************** IO Interposing Methods ***************************/
+
+// Function pointers to original functions
+static NtCreateFileFn         gOriginalNtCreateFile;
+static NtReadFileFn           gOriginalNtReadFile;
+static NtReadFileScatterFn    gOriginalNtReadFileScatter;
+static NtWriteFileFn          gOriginalNtWriteFile;
+static NtWriteFileGatherFn    gOriginalNtWriteFileGather;
+static NtFlushBuffersFileFn   gOriginalNtFlushBuffersFile;
+static NtQueryFullAttributesFileFn gOriginalNtQueryFullAttributesFile;
+
+static NTSTATUS NTAPI
+InterposedNtCreateFile(PHANDLE aFileHandle,
+                       ACCESS_MASK aDesiredAccess,
+                       POBJECT_ATTRIBUTES aObjectAttributes,
+                       PIO_STATUS_BLOCK aIoStatusBlock,
+                       PLARGE_INTEGER aAllocationSize,
+                       ULONG aFileAttributes,
+                       ULONG aShareAccess,
+                       ULONG aCreateDisposition,
+                       ULONG aCreateOptions,
+                       PVOID aEaBuffer,
+                       ULONG aEaLength)
+{
+  // Report IO
+  const wchar_t* buf =
+    aObjectAttributes ? aObjectAttributes->ObjectName->Buffer : L"";
+  uint32_t len =
+    aObjectAttributes ? aObjectAttributes->ObjectName->Length / sizeof(WCHAR) :
+                        0;
+  nsDependentSubstring filename(buf, len);
+  WinIOAutoObservation timer(IOInterposeObserver::OpCreateOrOpen, filename);
+
+  // Something is badly wrong if this function is undefined
+  MOZ_ASSERT(gOriginalNtCreateFile);
+
+  // Execute original function
+  return gOriginalNtCreateFile(aFileHandle,
+                               aDesiredAccess,
+                               aObjectAttributes,
+                               aIoStatusBlock,
+                               aAllocationSize,
+                               aFileAttributes,
+                               aShareAccess,
+                               aCreateDisposition,
+                               aCreateOptions,
+                               aEaBuffer,
+                               aEaLength);
+}
+
+static NTSTATUS NTAPI
+InterposedNtReadFile(HANDLE aFileHandle,
+                     HANDLE aEvent,
+                     PIO_APC_ROUTINE aApc,
+                     PVOID aApcCtx,
+                     PIO_STATUS_BLOCK aIoStatus,
+                     PVOID aBuffer,
+                     ULONG aLength,
+                     PLARGE_INTEGER aOffset,
+                     PULONG aKey)
+{
+  // Report IO
+  WinIOAutoObservation timer(IOInterposeObserver::OpRead, aFileHandle, aOffset);
+
+  // Something is badly wrong if this function is undefined
+  MOZ_ASSERT(gOriginalNtReadFile);
+
+  // Execute original function
+  return gOriginalNtReadFile(aFileHandle,
+                             aEvent,
+                             aApc,
+                             aApcCtx,
+                             aIoStatus,
+                             aBuffer,
+                             aLength,
+                             aOffset,
+                             aKey);
+}
+
+static NTSTATUS NTAPI
+InterposedNtReadFileScatter(HANDLE aFileHandle,
+                            HANDLE aEvent,
+                            PIO_APC_ROUTINE aApc,
+                            PVOID aApcCtx,
+                            PIO_STATUS_BLOCK aIoStatus,
+                            FILE_SEGMENT_ELEMENT* aSegments,
+                            ULONG aLength,
+                            PLARGE_INTEGER aOffset,
+                            PULONG aKey)
+{
+  // Report IO
+  WinIOAutoObservation timer(IOInterposeObserver::OpRead, aFileHandle, aOffset);
+
+  // Something is badly wrong if this function is undefined
+  MOZ_ASSERT(gOriginalNtReadFileScatter);
+
+  // Execute original function
+  return gOriginalNtReadFileScatter(aFileHandle,
+                                    aEvent,
+                                    aApc,
+                                    aApcCtx,
+                                    aIoStatus,
+                                    aSegments,
+                                    aLength,
+                                    aOffset,
+                                    aKey);
+}
+
+// Interposed NtWriteFile function
+static NTSTATUS NTAPI
+InterposedNtWriteFile(HANDLE aFileHandle,
+                      HANDLE aEvent,
+                      PIO_APC_ROUTINE aApc,
+                      PVOID aApcCtx,
+                      PIO_STATUS_BLOCK aIoStatus,
+                      PVOID aBuffer,
+                      ULONG aLength,
+                      PLARGE_INTEGER aOffset,
+                      PULONG aKey)
+{
+  // Report IO
+  WinIOAutoObservation timer(IOInterposeObserver::OpWrite, aFileHandle,
+                             aOffset);
+
+  // Something is badly wrong if this function is undefined
+  MOZ_ASSERT(gOriginalNtWriteFile);
+
+  // Execute original function
+  return gOriginalNtWriteFile(aFileHandle,
+                              aEvent,
+                              aApc,
+                              aApcCtx,
+                              aIoStatus,
+                              aBuffer,
+                              aLength,
+                              aOffset,
+                              aKey);
+}
+
+// Interposed NtWriteFileGather function
+static NTSTATUS NTAPI
+InterposedNtWriteFileGather(HANDLE aFileHandle,
+                            HANDLE aEvent,
+                            PIO_APC_ROUTINE aApc,
+                            PVOID aApcCtx,
+                            PIO_STATUS_BLOCK aIoStatus,
+                            FILE_SEGMENT_ELEMENT* aSegments,
+                            ULONG aLength,
+                            PLARGE_INTEGER aOffset,
+                            PULONG aKey)
+{
+  // Report IO
+  WinIOAutoObservation timer(IOInterposeObserver::OpWrite, aFileHandle,
+                             aOffset);
+
+  // Something is badly wrong if this function is undefined
+  MOZ_ASSERT(gOriginalNtWriteFileGather);
+
+  // Execute original function
+  return gOriginalNtWriteFileGather(aFileHandle,
+                                    aEvent,
+                                    aApc,
+                                    aApcCtx,
+                                    aIoStatus,
+                                    aSegments,
+                                    aLength,
+                                    aOffset,
+                                    aKey);
+}
+
+static NTSTATUS NTAPI
+InterposedNtFlushBuffersFile(HANDLE aFileHandle,
+                             PIO_STATUS_BLOCK aIoStatusBlock)
+{
+  // Report IO
+  WinIOAutoObservation timer(IOInterposeObserver::OpFSync, aFileHandle,
+                             nullptr);
+
+  // Something is badly wrong if this function is undefined
+  MOZ_ASSERT(gOriginalNtFlushBuffersFile);
+
+  // Execute original function
+  return gOriginalNtFlushBuffersFile(aFileHandle,
+                                     aIoStatusBlock);
+}
+
+static NTSTATUS NTAPI
+InterposedNtQueryFullAttributesFile(
+    POBJECT_ATTRIBUTES aObjectAttributes,
+    PFILE_NETWORK_OPEN_INFORMATION aFileInformation)
+{
+  // Report IO
+  const wchar_t* buf =
+    aObjectAttributes ? aObjectAttributes->ObjectName->Buffer : L"";
+  uint32_t len =
+    aObjectAttributes ? aObjectAttributes->ObjectName->Length / sizeof(WCHAR) :
+                        0;
+  nsDependentSubstring filename(buf, len);
+  WinIOAutoObservation timer(IOInterposeObserver::OpStat, filename);
+
+  // Something is badly wrong if this function is undefined
+  MOZ_ASSERT(gOriginalNtQueryFullAttributesFile);
+
+  // Execute original function
+  return gOriginalNtQueryFullAttributesFile(aObjectAttributes,
+                                            aFileInformation);
+}
+
+} // namespace
+
+/******************************** IO Poisoning ********************************/
+
+// Windows DLL interceptor
+static WindowsDllInterceptor sNtDllInterceptor;
+
+namespace mozilla {
+
+void
+InitPoisonIOInterposer()
+{
+  // Don't poison twice... as this function may only be invoked on the main
+  // thread when no other threads are running, it safe to allow multiple calls
+  // to InitPoisonIOInterposer() without complaining (ie. failing assertions).
+  if (sIOPoisoned) {
+    return;
+  }
+  sIOPoisoned = true;
+
+  // Stdout and Stderr are OK.
+  MozillaRegisterDebugFD(1);
+  MozillaRegisterDebugFD(2);
+
+#ifdef MOZ_REPLACE_MALLOC
+  // The contract with InitDebugFd is that the given registry can be used
+  // at any moment, so the instance needs to persist longer than the scope
+  // of this functions.
+  static DebugFdRegistry registry;
+  ReplaceMalloc::InitDebugFd(registry);
+#endif
+
+  // Initialize dll interceptor and add hooks
+  sNtDllInterceptor.Init("ntdll.dll");
+  sNtDllInterceptor.AddHook(
+    "NtCreateFile",
+    reinterpret_cast<intptr_t>(InterposedNtCreateFile),
+    reinterpret_cast<void**>(&gOriginalNtCreateFile));
+  sNtDllInterceptor.AddHook(
+    "NtReadFile",
+    reinterpret_cast<intptr_t>(InterposedNtReadFile),
+    reinterpret_cast<void**>(&gOriginalNtReadFile));
+  sNtDllInterceptor.AddHook(
+    "NtReadFileScatter",
+    reinterpret_cast<intptr_t>(InterposedNtReadFileScatter),
+    reinterpret_cast<void**>(&gOriginalNtReadFileScatter));
+  sNtDllInterceptor.AddHook(
+    "NtWriteFile",
+    reinterpret_cast<intptr_t>(InterposedNtWriteFile),
+    reinterpret_cast<void**>(&gOriginalNtWriteFile));
+  sNtDllInterceptor.AddHook(
+    "NtWriteFileGather",
+    reinterpret_cast<intptr_t>(InterposedNtWriteFileGather),
+    reinterpret_cast<void**>(&gOriginalNtWriteFileGather));
+  sNtDllInterceptor.AddHook(
+    "NtFlushBuffersFile",
+    reinterpret_cast<intptr_t>(InterposedNtFlushBuffersFile),
+    reinterpret_cast<void**>(&gOriginalNtFlushBuffersFile));
+  sNtDllInterceptor.AddHook(
+    "NtQueryFullAttributesFile",
+    reinterpret_cast<intptr_t>(InterposedNtQueryFullAttributesFile),
+    reinterpret_cast<void**>(&gOriginalNtQueryFullAttributesFile));
+}
+
+void
+ClearPoisonIOInterposer()
+{
+  MOZ_ASSERT(false);
+  if (sIOPoisoned) {
+    // Destroy the DLL interceptor
+    sIOPoisoned = false;
+    sNtDllInterceptor = WindowsDllInterceptor();
+  }
+}
+
+} // namespace mozilla
diff --git a/xpcom/build/ServiceList.h b/xpcom/build/ServiceList.h
new file mode 100644
index 000000000..3bb8308dd
--- /dev/null
+++ b/xpcom/build/ServiceList.h
@@ -0,0 +1,46 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+// IWYU pragma: private, include "mozilla/Services.h"
+
+MOZ_SERVICE(ChromeRegistryService, nsIChromeRegistry,
+            "@mozilla.org/chrome/chrome-registry;1")
+MOZ_SERVICE(ToolkitChromeRegistryService, nsIToolkitChromeRegistry,
+            "@mozilla.org/chrome/chrome-registry;1")
+MOZ_SERVICE(XULChromeRegistryService, nsIXULChromeRegistry,
+            "@mozilla.org/chrome/chrome-registry;1")
+MOZ_SERVICE(XULOverlayProviderService, nsIXULOverlayProvider,
+            "@mozilla.org/chrome/chrome-registry;1")
+MOZ_SERVICE(IOService, nsIIOService,
+            "@mozilla.org/network/io-service;1")
+MOZ_SERVICE(ObserverService, nsIObserverService,
+            "@mozilla.org/observer-service;1")
+MOZ_SERVICE(StringBundleService, nsIStringBundleService,
+            "@mozilla.org/intl/stringbundle;1")
+MOZ_SERVICE(XPConnect, nsIXPConnect,
+            "@mozilla.org/js/xpc/XPConnect;1")
+MOZ_SERVICE(InDOMUtils, inIDOMUtils,
+            "@mozilla.org/inspector/dom-utils;1")
+MOZ_SERVICE(PermissionManager, nsIPermissionManager,
+            "@mozilla.org/permissionmanager;1");
+MOZ_SERVICE(ServiceWorkerManager, nsIServiceWorkerManager,
+            "@mozilla.org/serviceworkers/manager;1");
+MOZ_SERVICE(AsyncShutdown, nsIAsyncShutdownService,
+            "@mozilla.org/async-shutdown-service;1")
+MOZ_SERVICE(UUIDGenerator, nsIUUIDGenerator,
+            "@mozilla.org/uuid-generator;1");
+MOZ_SERVICE(GfxInfo, nsIGfxInfo,
+            "@mozilla.org/gfx/info;1");
+
+#ifdef MOZ_USE_NAMESPACE
+namespace mozilla {
+#endif
+
+MOZ_SERVICE(HistoryService, IHistory,
+            "@mozilla.org/browser/history;1")
+
+#ifdef MOZ_USE_NAMESPACE
+} // namespace mozilla
+#endif
diff --git a/xpcom/build/Services.cpp b/xpcom/build/Services.cpp
new file mode 100644
index 000000000..6c521391e
--- /dev/null
+++ b/xpcom/build/Services.cpp
@@ -0,0 +1,71 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Likely.h"
+#include "mozilla/Services.h"
+#include "nsComponentManager.h"
+#include "nsIObserverService.h"
+#include "nsNetCID.h"
+#include "nsObserverService.h"
+#include "nsXPCOMPrivate.h"
+#include "nsIIOService.h"
+#include "nsIDirectoryService.h"
+#include "nsIChromeRegistry.h"
+#include "nsIStringBundle.h"
+#include "nsIToolkitChromeRegistry.h"
+#include "nsIXULOverlayProvider.h"
+#include "IHistory.h"
+#include "nsIXPConnect.h"
+#include "inIDOMUtils.h"
+#include "nsIPermissionManager.h"
+#include "nsIServiceWorkerManager.h"
+#include "nsIAsyncShutdown.h"
+#include "nsIUUIDGenerator.h"
+#include "nsIGfxInfo.h"
+
+using namespace mozilla;
+using namespace mozilla::services;
+
+/*
+ * Define a global variable and a getter for every service in ServiceList.
+ * eg. gIOService and GetIOService()
+ */
+#define MOZ_SERVICE(NAME, TYPE, CONTRACT_ID)                            \
+  static TYPE* g##NAME = nullptr;                                       \
+                                                                        \
+  already_AddRefed<TYPE>                                                \
+  mozilla::services::Get##NAME()                                        \
+  {                                                                     \
+    if (MOZ_UNLIKELY(gXPCOMShuttingDown)) {                             \
+      return nullptr;                                                   \
+    }                                                                   \
+    if (!g##NAME) {                                                     \
+      nsCOMPtr<TYPE> os = do_GetService(CONTRACT_ID);                   \
+      os.swap(g##NAME);                                                 \
+    }                                                                   \
+    nsCOMPtr<TYPE> ret = g##NAME;                                       \
+    return ret.forget();                                                \
+  }                                                                     \
+  NS_EXPORT_(already_AddRefed<TYPE>)                                    \
+  mozilla::services::_external_Get##NAME()                              \
+  {                                                                     \
+    return Get##NAME();                                                 \
+  }
+
+#include "ServiceList.h"
+#undef MOZ_SERVICE
+
+/**
+ * Clears service cache, sets gXPCOMShuttingDown
+ */
+void
+mozilla::services::Shutdown()
+{
+  gXPCOMShuttingDown = true;
+#define MOZ_SERVICE(NAME, TYPE, CONTRACT_ID) NS_IF_RELEASE(g##NAME);
+#include "ServiceList.h"
+#undef MOZ_SERVICE
+}
diff --git a/xpcom/build/Services.h b/xpcom/build/Services.h
new file mode 100644
index 000000000..84a355399
--- /dev/null
+++ b/xpcom/build/Services.h
@@ -0,0 +1,45 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_Services_h
+#define mozilla_Services_h
+
+#include "nscore.h"
+#include "nsCOMPtr.h"
+
+#define MOZ_USE_NAMESPACE
+#define MOZ_SERVICE(NAME, TYPE, SERVICE_CID) class TYPE;
+
+#include "ServiceList.h"
+#undef MOZ_SERVICE
+#undef MOZ_USE_NAMESPACE
+
+namespace mozilla {
+namespace services {
+
+#ifdef MOZILLA_INTERNAL_API
+#define MOZ_SERVICE(NAME, TYPE, SERVICE_CID)                        \
+    already_AddRefed<TYPE> Get##NAME();                             \
+    NS_EXPORT_(already_AddRefed<TYPE>) _external_Get##NAME();
+
+#include "ServiceList.h"
+#undef MOZ_SERVICE
+#else
+#define MOZ_SERVICE(NAME, TYPE, SERVICE_CID)                        \
+    NS_IMPORT_(already_AddRefed<TYPE>) _external_Get##NAME();       \
+    inline already_AddRefed<TYPE> Get##NAME()                       \
+    {                                                               \
+        return _external_Get##NAME();                               \
+    }
+
+#include "ServiceList.h"
+#undef MOZ_SERVICE
+#endif
+
+} // namespace services
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/build/XPCOM.h b/xpcom/build/XPCOM.h
new file mode 100644
index 000000000..f52a87c69
--- /dev/null
+++ b/xpcom/build/XPCOM.h
@@ -0,0 +1,178 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_XPCOM_h
+#define mozilla_XPCOM_h
+
+// NOTE: the following headers are sorted topologically, not alphabetically.
+// Do not reorder them without review from bsmedberg.
+
+// system headers required by XPCOM headers
+
+#include <string.h>
+
+// core headers required by pretty much everything else
+
+#include "nscore.h"
+
+#include "nsXPCOMCID.h"
+#include "nsXPCOM.h"
+
+#include "nsError.h"
+#include "nsDebug.h"
+#include "nsMemory.h"
+
+#include "nsID.h"
+
+#include "nsISupports.h"
+
+#include "nsTArray.h"
+#include "nsTWeakRef.h"
+
+#include "nsCOMPtr.h"
+#include "nsCOMArray.h"
+
+#ifndef MOZILLA_INTERNAL_API
+#include "nsStringAPI.h"
+#else
+#include "nsString.h"
+#include "nsReadableUtils.h"
+#include "nsNativeCharsetUtils.h"
+#endif
+
+#include "nsISupportsUtils.h"
+#include "nsISupportsImpl.h"
+
+// core data structures
+
+#include "nsTHashtable.h"
+#include "nsHashKeys.h"
+#include "nsBaseHashtable.h"
+#include "nsDataHashtable.h"
+#include "nsInterfaceHashtable.h"
+#include "nsClassHashtable.h"
+#include "nsRefPtrHashtable.h"
+
+// interfaces that inherit directly from nsISupports
+
+#include "nsIArray.h"
+#include "nsIAtom.h"
+#include "nsIAtomService.h"
+#include "nsICategoryManager.h"
+#include "nsIClassInfo.h"
+#include "nsIComponentManager.h"
+#include "nsIConsoleListener.h"
+#include "nsIConsoleMessage.h"
+#include "nsIConsoleService.h"
+#include "nsIDebug2.h"
+#include "nsIDirectoryEnumerator.h"
+#include "nsIEnvironment.h"
+#include "nsIErrorService.h"
+#include "nsIEventTarget.h"
+#include "nsIException.h"
+#include "nsIFactory.h"
+#include "nsIFile.h"
+#include "nsIHashable.h"
+#include "nsIINIParser.h"
+#include "nsIInputStream.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsILineInputStream.h"
+#include "nsIMemory.h"
+#include "nsIMutable.h"
+#include "nsIObserver.h"
+#include "nsIObserverService.h"
+#include "nsIOutputStream.h"
+#include "nsIProcess.h"
+#include "nsIProperties.h"
+#include "nsIPropertyBag2.h"
+#include "nsIRunnable.h"
+#include "nsISeekableStream.h"
+#include "nsISerializable.h"
+#include "nsIServiceManager.h"
+#include "nsIScriptableInputStream.h"
+#include "nsISimpleEnumerator.h"
+#include "nsIStreamBufferAccess.h"
+#include "nsIStringEnumerator.h"
+#include "nsIStorageStream.h"
+#include "nsISupportsIterators.h"
+#include "nsISupportsPrimitives.h"
+#include "nsISupportsPriority.h"
+#include "nsIThreadManager.h"
+#include "nsITimer.h"
+#include "nsIUUIDGenerator.h"
+#include "nsIUnicharInputStream.h"
+#include "nsIUnicharOutputStream.h"
+#include "nsIUnicharLineInputStream.h"
+#include "nsIVariant.h"
+#include "nsIVersionComparator.h"
+#include "nsIWritablePropertyBag2.h"
+
+// interfaces that include something above
+
+#include "nsIAsyncInputStream.h"
+#include "nsIAsyncOutputStream.h"
+#include "nsIBinaryInputStream.h"
+#include "nsIBinaryOutputStream.h"
+#include "nsIConverterInputStream.h"
+#include "nsIConverterOutputStream.h"
+#include "nsIInputStreamTee.h"
+#include "nsIMultiplexInputStream.h"
+#include "nsIMutableArray.h"
+#include "nsIPersistentProperties2.h"
+#include "nsIStringStream.h"
+#include "nsIThread.h"
+#include "nsIThreadPool.h"
+
+// interfaces that include something above
+
+#include "nsILocalFileWin.h"
+#include "nsIObjectInputStream.h"
+#include "nsIObjectOutputStream.h"
+#include "nsIPipe.h"
+
+#ifdef MOZ_WIDGET_COCOA
+#include "nsILocalFileMac.h"
+#include "nsIMacUtils.h"
+#endif
+
+// xpcom/glue utility headers
+
+#include "nsComponentManagerUtils.h"
+#include "nsServiceManagerUtils.h"
+
+#include "nsIWeakReferenceUtils.h"
+#include "nsWeakReference.h"
+
+#include "nsArrayEnumerator.h"
+#include "nsArrayUtils.h"
+#include "nsCRTGlue.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsDeque.h"
+#include "nsEnumeratorUtils.h"
+#include "nsIClassInfoImpl.h"
+#include "mozilla/ModuleUtils.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsINIParser.h"
+#include "nsProxyRelease.h"
+#include "nsTObserverArray.h"
+#include "nsTextFormatter.h"
+#include "nsThreadUtils.h"
+#include "nsVersionComparator.h"
+#include "nsXPTCUtils.h"
+
+// xpcom/base utility headers
+
+#include "nsAgg.h"
+#include "nsAutoRef.h"
+#include "nsInterfaceRequestorAgg.h"
+
+// xpcom/io utility headers
+
+#include "nsAppDirectoryServiceDefs.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsDirectoryServiceUtils.h"
+
+#endif // mozilla_XPCOM_h
diff --git a/xpcom/build/XPCOMInit.cpp b/xpcom/build/XPCOMInit.cpp
new file mode 100644
index 000000000..c72ea48d7
--- /dev/null
+++ b/xpcom/build/XPCOMInit.cpp
@@ -0,0 +1,1126 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "base/basictypes.h"
+
+#include "mozilla/AbstractThread.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/Poison.h"
+#include "mozilla/SharedThreadPool.h"
+#include "mozilla/XPCOM.h"
+#include "nsXULAppAPI.h"
+
+#include "nsXPCOMPrivate.h"
+#include "nsXPCOMCIDInternal.h"
+
+#include "mozilla/layers/ImageBridgeChild.h"
+#include "mozilla/layers/CompositorBridgeParent.h"
+#include "mozilla/dom/VideoDecoderManagerChild.h"
+
+#include "prlink.h"
+
+#include "nsCycleCollector.h"
+#include "nsObserverList.h"
+#include "nsObserverService.h"
+#include "nsProperties.h"
+#include "nsPersistentProperties.h"
+#include "nsScriptableInputStream.h"
+#include "nsBinaryStream.h"
+#include "nsStorageStream.h"
+#include "nsPipe.h"
+#include "nsScriptableBase64Encoder.h"
+
+#include "nsMemoryImpl.h"
+#include "nsDebugImpl.h"
+#include "nsTraceRefcnt.h"
+#include "nsErrorService.h"
+
+// Disable deprecation warnings generated by nsISupportsArray and associated
+// classes.
+#if defined(__GNUC__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+#elif defined(_MSC_VER)
+#pragma warning (push)
+#pragma warning (disable : 4996)
+#endif
+
+#include "nsSupportsArray.h"
+
+#if defined(__GNUC__)
+#pragma GCC diagnostic pop
+#elif defined(_MSC_VER)
+#pragma warning (pop)
+#endif
+
+#include "nsArray.h"
+#include "nsINIParserImpl.h"
+#include "nsSupportsPrimitives.h"
+#include "nsConsoleService.h"
+
+#include "nsComponentManager.h"
+#include "nsCategoryManagerUtils.h"
+#include "nsIServiceManager.h"
+
+#include "nsThreadManager.h"
+#include "nsThreadPool.h"
+
+#include "xptinfo.h"
+#include "nsIInterfaceInfoManager.h"
+#include "xptiprivate.h"
+#include "mozilla/XPTInterfaceInfoManager.h"
+
+#include "nsTimerImpl.h"
+#include "TimerThread.h"
+
+#include "nsThread.h"
+#include "nsProcess.h"
+#include "nsEnvironment.h"
+#include "nsVersionComparatorImpl.h"
+
+#include "nsIFile.h"
+#include "nsLocalFile.h"
+#if defined(XP_UNIX)
+#include "nsNativeCharsetUtils.h"
+#endif
+#include "nsDirectoryService.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsCategoryManager.h"
+#include "nsICategoryManager.h"
+#include "nsMultiplexInputStream.h"
+
+#include "nsStringStream.h"
+extern nsresult nsStringInputStreamConstructor(nsISupports*, REFNSIID, void**);
+
+#include "nsAtomService.h"
+#include "nsAtomTable.h"
+#include "nsISupportsImpl.h"
+
+#include "nsHashPropertyBag.h"
+
+#include "nsUnicharInputStream.h"
+#include "nsVariant.h"
+
+#include "nsUUIDGenerator.h"
+
+#include "nsIOUtil.h"
+
+#include "SpecialSystemDirectory.h"
+
+#if defined(XP_WIN)
+#include "mozilla/WindowsVersion.h"
+#include "nsWindowsRegKey.h"
+#endif
+
+#ifdef MOZ_WIDGET_COCOA
+#include "nsMacUtilsImpl.h"
+#endif
+
+#include "nsSystemInfo.h"
+#include "nsMemoryReporterManager.h"
+#include "nsMemoryInfoDumper.h"
+#include "nsSecurityConsoleMessage.h"
+#include "nsMessageLoop.h"
+
+#include "nsStatusReporterManager.h"
+
+#include <locale.h>
+#include "mozilla/Services.h"
+#include "mozilla/Omnijar.h"
+#include "mozilla/HangMonitor.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/BackgroundHangMonitor.h"
+
+#include "nsChromeRegistry.h"
+#include "nsChromeProtocolHandler.h"
+#include "mozilla/PoisonIOInterposer.h"
+#include "mozilla/LateWriteChecks.h"
+
+#include "mozilla/scache/StartupCache.h"
+
+#include "base/at_exit.h"
+#include "base/command_line.h"
+#include "base/message_loop.h"
+
+#include "mozilla/ipc/BrowserProcessSubThread.h"
+#include "mozilla/AvailableMemoryTracker.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/CountingAllocatorBase.h"
+#include "mozilla/SystemMemoryReporter.h"
+#include "mozilla/UniquePtr.h"
+
+#include "mozilla/ipc/GeckoChildProcessHost.h"
+
+#include "ogg/ogg.h"
+#if defined(MOZ_VPX) && !defined(MOZ_VPX_NO_MEM_REPORTING)
+#if defined(HAVE_STDINT_H)
+// mozilla-config.h defines HAVE_STDINT_H, and then it's defined *again* in
+// vpx_config.h (which we include via vpx_mem.h, below). This redefinition
+// triggers a build warning on MSVC, so we have to #undef it first.
+#undef HAVE_STDINT_H
+#endif
+#include "vpx_mem/vpx_mem.h"
+#endif
+
+#include "GeckoProfiler.h"
+
+#include "jsapi.h"
+#include "js/Initialization.h"
+
+#include "gfxPlatform.h"
+
+#if EXPOSE_INTL_API
+#include "unicode/putil.h"
+#endif
+
+using namespace mozilla;
+using base::AtExitManager;
+using mozilla::ipc::BrowserProcessSubThread;
+
+namespace {
+
+static AtExitManager* sExitManager;
+static MessageLoop* sMessageLoop;
+static bool sCommandLineWasInitialized;
+static BrowserProcessSubThread* sIOThread;
+static BackgroundHangMonitor* sMainHangMonitor;
+
+} /* anonymous namespace */
+
+// Registry Factory creation function defined in nsRegistry.cpp
+// We hook into this function locally to create and register the registry
+// Since noone outside xpcom needs to know about this and nsRegistry.cpp
+// does not have a local include file, we are putting this definition
+// here rather than in nsIRegistry.h
+extern nsresult NS_RegistryGetFactory(nsIFactory** aFactory);
+extern nsresult NS_CategoryManagerGetFactory(nsIFactory**);
+
+#ifdef XP_WIN
+extern nsresult CreateAnonTempFileRemover();
+#endif
+
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsProcess)
+
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsSupportsID)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsSupportsString)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsSupportsCString)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsSupportsPRBool)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsSupportsPRUint8)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsSupportsPRUint16)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsSupportsPRUint32)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsSupportsPRUint64)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsSupportsPRTime)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsSupportsChar)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsSupportsPRInt16)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsSupportsPRInt32)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsSupportsPRInt64)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsSupportsFloat)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsSupportsDouble)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsSupportsVoid)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsSupportsInterfacePointer)
+
+NS_GENERIC_FACTORY_CONSTRUCTOR_INIT(nsConsoleService, Init)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsAtomService)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsTimer)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsBinaryOutputStream)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsBinaryInputStream)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsStorageStream)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsVersionComparatorImpl)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsScriptableBase64Encoder)
+
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsVariantCC)
+
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsHashPropertyBagCC)
+
+NS_GENERIC_AGGREGATED_CONSTRUCTOR(nsProperties)
+
+NS_GENERIC_FACTORY_CONSTRUCTOR_INIT(nsUUIDGenerator, Init)
+
+#ifdef MOZ_WIDGET_COCOA
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsMacUtilsImpl)
+#endif
+
+NS_GENERIC_FACTORY_CONSTRUCTOR_INIT(nsSystemInfo, Init)
+
+NS_GENERIC_FACTORY_CONSTRUCTOR_INIT(nsMemoryReporterManager, Init)
+
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsMemoryInfoDumper)
+
+NS_GENERIC_FACTORY_CONSTRUCTOR_INIT(nsStatusReporterManager, Init)
+
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsIOUtil)
+
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsSecurityConsoleMessage)
+
+static nsresult
+nsThreadManagerGetSingleton(nsISupports* aOuter,
+                            const nsIID& aIID,
+                            void** aInstancePtr)
+{
+  NS_ASSERTION(aInstancePtr, "null outptr");
+  if (NS_WARN_IF(aOuter)) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+
+  return nsThreadManager::get().QueryInterface(aIID, aInstancePtr);
+}
+
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsThreadPool)
+
+static nsresult
+nsXPTIInterfaceInfoManagerGetSingleton(nsISupports* aOuter,
+                                       const nsIID& aIID,
+                                       void** aInstancePtr)
+{
+  NS_ASSERTION(aInstancePtr, "null outptr");
+  if (NS_WARN_IF(aOuter)) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+
+  nsCOMPtr<nsIInterfaceInfoManager> iim(XPTInterfaceInfoManager::GetSingleton());
+  if (!iim) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return iim->QueryInterface(aIID, aInstancePtr);
+}
+
+nsComponentManagerImpl* nsComponentManagerImpl::gComponentManager = nullptr;
+bool gXPCOMShuttingDown = false;
+bool gXPCOMThreadsShutDown = false;
+char16_t* gGREBinPath = nullptr;
+
+static NS_DEFINE_CID(kComponentManagerCID, NS_COMPONENTMANAGER_CID);
+static NS_DEFINE_CID(kINIParserFactoryCID, NS_INIPARSERFACTORY_CID);
+
+NS_DEFINE_NAMED_CID(NS_CHROMEREGISTRY_CID);
+NS_DEFINE_NAMED_CID(NS_CHROMEPROTOCOLHANDLER_CID);
+
+NS_DEFINE_NAMED_CID(NS_SECURITY_CONSOLE_MESSAGE_CID);
+
+NS_GENERIC_FACTORY_SINGLETON_CONSTRUCTOR(nsChromeRegistry,
+                                         nsChromeRegistry::GetSingleton)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsChromeProtocolHandler)
+
+#define NS_PERSISTENTPROPERTIES_CID NS_IPERSISTENTPROPERTIES_CID /* sigh */
+
+static already_AddRefed<nsIFactory>
+CreateINIParserFactory(const mozilla::Module& aModule,
+                       const mozilla::Module::CIDEntry& aEntry)
+{
+  nsCOMPtr<nsIFactory> f = new nsINIParserFactory();
+  return f.forget();
+}
+
+#define COMPONENT(NAME, Ctor) static NS_DEFINE_CID(kNS_##NAME##_CID, NS_##NAME##_CID);
+#define COMPONENT_M(NAME, Ctor, Selector) static NS_DEFINE_CID(kNS_##NAME##_CID, NS_##NAME##_CID);
+#include "XPCOMModule.inc"
+#undef COMPONENT
+#undef COMPONENT_M
+
+#define COMPONENT(NAME, Ctor) { &kNS_##NAME##_CID, false, nullptr, Ctor },
+#define COMPONENT_M(NAME, Ctor, Selector) { &kNS_##NAME##_CID, false, nullptr, Ctor, Selector },
+const mozilla::Module::CIDEntry kXPCOMCIDEntries[] = {
+  { &kComponentManagerCID, true, nullptr, nsComponentManagerImpl::Create, Module::ALLOW_IN_GPU_PROCESS },
+  { &kINIParserFactoryCID, false, CreateINIParserFactory },
+#include "XPCOMModule.inc"
+  { &kNS_CHROMEREGISTRY_CID, false, nullptr, nsChromeRegistryConstructor },
+  { &kNS_CHROMEPROTOCOLHANDLER_CID, false, nullptr, nsChromeProtocolHandlerConstructor },
+  { &kNS_SECURITY_CONSOLE_MESSAGE_CID, false, nullptr, nsSecurityConsoleMessageConstructor },
+  { nullptr }
+};
+#undef COMPONENT
+#undef COMPONENT_M
+
+#define COMPONENT(NAME, Ctor) { NS_##NAME##_CONTRACTID, &kNS_##NAME##_CID },
+#define COMPONENT_M(NAME, Ctor, Selector) { NS_##NAME##_CONTRACTID, &kNS_##NAME##_CID, Selector },
+const mozilla::Module::ContractIDEntry kXPCOMContracts[] = {
+#include "XPCOMModule.inc"
+  { NS_CHROMEREGISTRY_CONTRACTID, &kNS_CHROMEREGISTRY_CID },
+  { NS_NETWORK_PROTOCOL_CONTRACTID_PREFIX "chrome", &kNS_CHROMEPROTOCOLHANDLER_CID },
+  { NS_INIPARSERFACTORY_CONTRACTID, &kINIParserFactoryCID },
+  { NS_SECURITY_CONSOLE_MESSAGE_CONTRACTID, &kNS_SECURITY_CONSOLE_MESSAGE_CID },
+  { nullptr }
+};
+#undef COMPONENT
+#undef COMPONENT_M
+
+const mozilla::Module kXPCOMModule = {
+  mozilla::Module::kVersion, kXPCOMCIDEntries, kXPCOMContracts,
+  nullptr,
+  nullptr,
+  nullptr,
+  nullptr,
+  Module::ALLOW_IN_GPU_PROCESS
+};
+
+// gDebug will be freed during shutdown.
+static nsIDebug2* gDebug = nullptr;
+
+EXPORT_XPCOM_API(nsresult)
+NS_GetDebug(nsIDebug2** aResult)
+{
+  return nsDebugImpl::Create(nullptr,  NS_GET_IID(nsIDebug2), (void**)aResult);
+}
+
+EXPORT_XPCOM_API(nsresult)
+NS_InitXPCOM(nsIServiceManager** aResult,
+             nsIFile* aBinDirectory)
+{
+  return NS_InitXPCOM2(aResult, aBinDirectory, nullptr);
+}
+
+class ICUReporter final
+  : public nsIMemoryReporter
+  , public CountingAllocatorBase<ICUReporter>
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  static void* Alloc(const void*, size_t aSize)
+  {
+    return CountingMalloc(aSize);
+  }
+
+  static void* Realloc(const void*, void* aPtr, size_t aSize)
+  {
+    return CountingRealloc(aPtr, aSize);
+  }
+
+  static void Free(const void*, void* aPtr)
+  {
+    return CountingFree(aPtr);
+  }
+
+private:
+  NS_IMETHOD
+  CollectReports(nsIHandleReportCallback* aHandleReport, nsISupports* aData,
+                 bool aAnonymize) override
+  {
+    MOZ_COLLECT_REPORT(
+      "explicit/icu", KIND_HEAP, UNITS_BYTES, MemoryAllocated(),
+      "Memory used by ICU, a Unicode and globalization support library.");
+
+    return NS_OK;
+  }
+
+  ~ICUReporter() {}
+};
+
+NS_IMPL_ISUPPORTS(ICUReporter, nsIMemoryReporter)
+
+/* static */ template<> Atomic<size_t>
+CountingAllocatorBase<ICUReporter>::sAmount(0);
+
+class OggReporter final
+  : public nsIMemoryReporter
+  , public CountingAllocatorBase<OggReporter>
+{
+public:
+  NS_DECL_ISUPPORTS
+
+private:
+  NS_IMETHOD
+  CollectReports(nsIHandleReportCallback* aHandleReport, nsISupports* aData,
+                 bool aAnonymize) override
+  {
+    MOZ_COLLECT_REPORT(
+      "explicit/media/libogg", KIND_HEAP, UNITS_BYTES, MemoryAllocated(),
+      "Memory allocated through libogg for Ogg, Theora, and related media "
+      "files.");
+
+    return NS_OK;
+  }
+
+  ~OggReporter() {}
+};
+
+NS_IMPL_ISUPPORTS(OggReporter, nsIMemoryReporter)
+
+/* static */ template<> Atomic<size_t>
+CountingAllocatorBase<OggReporter>::sAmount(0);
+
+#ifdef MOZ_VPX
+class VPXReporter final
+  : public nsIMemoryReporter
+  , public CountingAllocatorBase<VPXReporter>
+{
+public:
+  NS_DECL_ISUPPORTS
+
+private:
+  NS_IMETHOD
+  CollectReports(nsIHandleReportCallback* aHandleReport, nsISupports* aData,
+                 bool aAnonymize) override
+  {
+    MOZ_COLLECT_REPORT(
+      "explicit/media/libvpx", KIND_HEAP, UNITS_BYTES, MemoryAllocated(),
+      "Memory allocated through libvpx for WebM media files.");
+
+    return NS_OK;
+  }
+
+  ~VPXReporter() {}
+};
+
+NS_IMPL_ISUPPORTS(VPXReporter, nsIMemoryReporter)
+
+/* static */ template<> Atomic<size_t>
+CountingAllocatorBase<VPXReporter>::sAmount(0);
+#endif /* MOZ_VPX */
+
+static double
+TimeSinceProcessCreation()
+{
+  bool ignore;
+  return (TimeStamp::Now() - TimeStamp::ProcessCreation(ignore)).ToMilliseconds();
+}
+
+static bool sInitializedJS = false;
+
+// Note that on OSX, aBinDirectory will point to .app/Contents/Resources/browser
+EXPORT_XPCOM_API(nsresult)
+NS_InitXPCOM2(nsIServiceManager** aResult,
+              nsIFile* aBinDirectory,
+              nsIDirectoryServiceProvider* aAppFileLocationProvider)
+{
+  static bool sInitialized = false;
+  if (sInitialized) {
+    return NS_ERROR_FAILURE;
+  }
+
+  sInitialized = true;
+
+  mozPoisonValueInit();
+
+  NS_LogInit();
+
+  NS_InitAtomTable();
+
+  mozilla::LogModule::Init();
+
+  JS_SetCurrentEmbedderTimeFunction(TimeSinceProcessCreation);
+
+  char aLocal;
+  profiler_init(&aLocal);
+  nsresult rv = NS_OK;
+
+  // We are not shutting down
+  gXPCOMShuttingDown = false;
+
+  // Initialize the available memory tracker before other threads have had a
+  // chance to start up, because the initialization is not thread-safe.
+  mozilla::AvailableMemoryTracker::Init();
+
+#ifdef XP_UNIX
+  // Discover the current value of the umask, and save it where
+  // nsSystemInfo::Init can retrieve it when necessary.  There is no way
+  // to read the umask without changing it, and the setting is process-
+  // global, so this must be done while we are still single-threaded; the
+  // nsSystemInfo object is typically created much later, when some piece
+  // of chrome JS wants it.  The system call is specified as unable to fail.
+  nsSystemInfo::gUserUmask = ::umask(0777);
+  ::umask(nsSystemInfo::gUserUmask);
+#endif
+
+  // Set up chromium libs
+  NS_ASSERTION(!sExitManager && !sMessageLoop, "Bad logic!");
+
+  if (!AtExitManager::AlreadyRegistered()) {
+    sExitManager = new AtExitManager();
+  }
+
+  MessageLoop* messageLoop = MessageLoop::current();
+  if (!messageLoop) {
+    sMessageLoop = new MessageLoopForUI(MessageLoop::TYPE_MOZILLA_PARENT);
+    sMessageLoop->set_thread_name("Gecko");
+    // Set experimental values for main thread hangs:
+    // 128ms for transient hangs and 8192ms for permanent hangs
+    sMessageLoop->set_hang_timeouts(128, 8192);
+  } else if (messageLoop->type() == MessageLoop::TYPE_MOZILLA_CHILD) {
+    messageLoop->set_thread_name("Gecko_Child");
+    messageLoop->set_hang_timeouts(128, 8192);
+  }
+
+  if (XRE_IsParentProcess() &&
+      !BrowserProcessSubThread::GetMessageLoop(BrowserProcessSubThread::IO)) {
+    UniquePtr<BrowserProcessSubThread> ioThread = MakeUnique<BrowserProcessSubThread>(BrowserProcessSubThread::IO);
+
+    base::Thread::Options options;
+    options.message_loop_type = MessageLoop::TYPE_IO;
+    if (NS_WARN_IF(!ioThread->StartWithOptions(options))) {
+      return NS_ERROR_FAILURE;
+    }
+
+    sIOThread = ioThread.release();
+  }
+
+  // Establish the main thread here.
+  rv = nsThreadManager::get().Init();
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  // Set up the timer globals/timer thread
+  rv = nsTimerImpl::Startup();
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+#ifndef ANDROID
+  // If the locale hasn't already been setup by our embedder,
+  // get us out of the "C" locale and into the system
+  if (strcmp(setlocale(LC_ALL, nullptr), "C") == 0) {
+    setlocale(LC_ALL, "");
+  }
+#endif
+
+#if defined(XP_UNIX)
+  NS_StartupNativeCharsetUtils();
+#endif
+
+  NS_StartupLocalFile();
+
+  StartupSpecialSystemDirectory();
+
+  nsDirectoryService::RealInit();
+
+  bool value;
+
+  if (aBinDirectory) {
+    rv = aBinDirectory->IsDirectory(&value);
+
+    if (NS_SUCCEEDED(rv) && value) {
+      nsDirectoryService::gService->Set(NS_XPCOM_INIT_CURRENT_PROCESS_DIR,
+                                        aBinDirectory);
+    }
+  }
+
+  if (aAppFileLocationProvider) {
+    rv = nsDirectoryService::gService->RegisterProvider(aAppFileLocationProvider);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+  }
+
+  nsCOMPtr<nsIFile> xpcomLib;
+  nsDirectoryService::gService->Get(NS_GRE_BIN_DIR,
+                                    NS_GET_IID(nsIFile),
+                                    getter_AddRefs(xpcomLib));
+  MOZ_ASSERT(xpcomLib);
+
+  // set gGREBinPath
+  nsAutoString path;
+  xpcomLib->GetPath(path);
+  gGREBinPath = ToNewUnicode(path);
+
+  xpcomLib->AppendNative(nsDependentCString(XPCOM_DLL));
+  nsDirectoryService::gService->Set(NS_XPCOM_LIBRARY_FILE, xpcomLib);
+
+  if (!mozilla::Omnijar::IsInitialized()) {
+    mozilla::Omnijar::Init();
+  }
+
+  if ((sCommandLineWasInitialized = !CommandLine::IsInitialized())) {
+#ifdef OS_WIN
+    CommandLine::Init(0, nullptr);
+#else
+    nsCOMPtr<nsIFile> binaryFile;
+    nsDirectoryService::gService->Get(NS_XPCOM_CURRENT_PROCESS_DIR,
+                                      NS_GET_IID(nsIFile),
+                                      getter_AddRefs(binaryFile));
+    if (NS_WARN_IF(!binaryFile)) {
+      return NS_ERROR_FAILURE;
+    }
+
+    rv = binaryFile->AppendNative(NS_LITERAL_CSTRING("nonexistent-executable"));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    nsCString binaryPath;
+    rv = binaryFile->GetNativePath(binaryPath);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    static char const* const argv = { strdup(binaryPath.get()) };
+    CommandLine::Init(1, &argv);
+#endif
+  }
+
+  NS_ASSERTION(nsComponentManagerImpl::gComponentManager == nullptr,
+               "CompMgr not null at init");
+
+  // Create the Component/Service Manager
+  nsComponentManagerImpl::gComponentManager = new nsComponentManagerImpl();
+  NS_ADDREF(nsComponentManagerImpl::gComponentManager);
+
+  // Global cycle collector initialization.
+  if (!nsCycleCollector_init()) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  // And start it up for this thread too.
+  nsCycleCollector_startup();
+
+  // Register ICU memory functions.  This really shouldn't be necessary: the
+  // JS engine should do this on its own inside JS_Init, and memory-reporting
+  // code should call a JSAPI function to observe ICU memory usage.  But we
+  // can't define the alloc/free functions in the JS engine, because it can't
+  // depend on the XPCOM-based memory reporting goop.  So for now, we have
+  // this oddness.
+  mozilla::SetICUMemoryFunctions();
+
+  // Do the same for libogg.
+  ogg_set_mem_functions(OggReporter::CountingMalloc,
+                        OggReporter::CountingCalloc,
+                        OggReporter::CountingRealloc,
+                        OggReporter::CountingFree);
+
+#if defined(MOZ_VPX) && !defined(MOZ_VPX_NO_MEM_REPORTING)
+  // And for VPX.
+  vpx_mem_set_functions(VPXReporter::CountingMalloc,
+                        VPXReporter::CountingCalloc,
+                        VPXReporter::CountingRealloc,
+                        VPXReporter::CountingFree,
+                        memcpy,
+                        memset,
+                        memmove);
+#endif
+
+#if EXPOSE_INTL_API && defined(MOZ_ICU_DATA_ARCHIVE)
+  nsCOMPtr<nsIFile> greDir;
+  nsDirectoryService::gService->Get(NS_GRE_DIR,
+                                    NS_GET_IID(nsIFile),
+                                    getter_AddRefs(greDir));
+  MOZ_ASSERT(greDir);
+  nsAutoCString nativeGREPath;
+  greDir->GetNativePath(nativeGREPath);
+  u_setDataDirectory(nativeGREPath.get());
+#endif
+
+  // Initialize the JS engine.
+  const char* jsInitFailureReason = JS_InitWithFailureDiagnostic();
+  if (jsInitFailureReason) {
+    NS_RUNTIMEABORT(jsInitFailureReason);
+  }
+  sInitializedJS = true;
+  
+  // Init AbstractThread.
+  AbstractThread::InitStatics();
+
+  rv = nsComponentManagerImpl::gComponentManager->Init();
+  if (NS_FAILED(rv)) {
+    NS_RELEASE(nsComponentManagerImpl::gComponentManager);
+    return rv;
+  }
+
+  if (aResult) {
+    NS_ADDREF(*aResult = nsComponentManagerImpl::gComponentManager);
+  }
+
+  // The iimanager constructor searches and registers XPT files.
+  // (We trigger the singleton's lazy construction here to make that happen.)
+  (void)XPTInterfaceInfoManager::GetSingleton();
+
+  // After autoreg, but before we actually instantiate any components,
+  // add any services listed in the "xpcom-directory-providers" category
+  // to the directory service.
+  nsDirectoryService::gService->RegisterCategoryProviders();
+
+  // Init SharedThreadPool (which needs the service manager).
+  SharedThreadPool::InitStatics();
+
+  // Force layout to spin up so that nsContentUtils is available for cx stack
+  // munging.  Note that layout registers a number of static atoms, and also
+  // seals the static atom table, so NS_RegisterStaticAtom may not be called
+  // beyond this point.
+  nsCOMPtr<nsISupports> componentLoader =
+    do_GetService("@mozilla.org/moz/jsloader;1");
+
+  mozilla::scache::StartupCache::GetSingleton();
+  mozilla::AvailableMemoryTracker::Activate();
+
+  // Notify observers of xpcom autoregistration start
+  NS_CreateServicesFromCategory(NS_XPCOM_STARTUP_CATEGORY,
+                                nullptr,
+                                NS_XPCOM_STARTUP_OBSERVER_ID);
+#ifdef XP_WIN
+  CreateAnonTempFileRemover();
+#endif
+
+  // We only want the SystemMemoryReporter running in one process, because it
+  // profiles the entire system.  The main process is the obvious place for
+  // it.
+  if (XRE_IsParentProcess()) {
+    mozilla::SystemMemoryReporter::Init();
+  }
+
+  // The memory reporter manager is up and running -- register our reporters.
+  RegisterStrongMemoryReporter(new ICUReporter());
+  RegisterStrongMemoryReporter(new OggReporter());
+#ifdef MOZ_VPX
+  RegisterStrongMemoryReporter(new VPXReporter());
+#endif
+
+  mozilla::Telemetry::Init();
+
+  mozilla::HangMonitor::Startup();
+  mozilla::BackgroundHangMonitor::Startup();
+
+  const MessageLoop* const loop = MessageLoop::current();
+  sMainHangMonitor = new mozilla::BackgroundHangMonitor(
+    loop->thread_name().c_str(),
+    loop->transient_hang_timeout(),
+    loop->permanent_hang_timeout());
+
+  return NS_OK;
+}
+
+EXPORT_XPCOM_API(nsresult)
+NS_InitMinimalXPCOM()
+{
+  mozPoisonValueInit();
+  NS_SetMainThread();
+  mozilla::TimeStamp::Startup();
+  NS_LogInit();
+  NS_InitAtomTable();
+  mozilla::LogModule::Init();
+
+  char aLocal;
+  profiler_init(&aLocal);
+
+  nsresult rv = nsThreadManager::get().Init();
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  // Set up the timer globals/timer thread.
+  rv = nsTimerImpl::Startup();
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  // Create the Component/Service Manager
+  nsComponentManagerImpl::gComponentManager = new nsComponentManagerImpl();
+  NS_ADDREF(nsComponentManagerImpl::gComponentManager);
+
+  rv = nsComponentManagerImpl::gComponentManager->Init();
+  if (NS_FAILED(rv)) {
+    NS_RELEASE(nsComponentManagerImpl::gComponentManager);
+    return rv;
+  }
+
+  // Global cycle collector initialization.
+  if (!nsCycleCollector_init()) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  AbstractThread::InitStatics();
+  SharedThreadPool::InitStatics();
+  mozilla::Telemetry::Init();
+  mozilla::HangMonitor::Startup();
+  mozilla::BackgroundHangMonitor::Startup();
+
+  return NS_OK;
+}
+
+//
+// NS_ShutdownXPCOM()
+//
+// The shutdown sequence for xpcom would be
+//
+// - Notify "xpcom-shutdown" for modules to release primary (root) references
+// - Shutdown XPCOM timers
+// - Notify "xpcom-shutdown-threads" for thread joins
+// - Shutdown the event queues
+// - Release the Global Service Manager
+//   - Release all service instances held by the global service manager
+//   - Release the Global Service Manager itself
+// - Release the Component Manager
+//   - Release all factories cached by the Component Manager
+//   - Notify module loaders to shut down
+//   - Unload Libraries
+//   - Release Contractid Cache held by Component Manager
+//   - Release dll abstraction held by Component Manager
+//   - Release the Registry held by Component Manager
+//   - Finally, release the component manager itself
+//
+EXPORT_XPCOM_API(nsresult)
+NS_ShutdownXPCOM(nsIServiceManager* aServMgr)
+{
+  return mozilla::ShutdownXPCOM(aServMgr);
+}
+
+namespace mozilla {
+
+void
+SetICUMemoryFunctions()
+{
+  static bool sICUReporterInitialized = false;
+  if (!sICUReporterInitialized) {
+    if (!JS_SetICUMemoryFunctions(ICUReporter::Alloc, ICUReporter::Realloc,
+                                  ICUReporter::Free)) {
+      NS_RUNTIMEABORT("JS_SetICUMemoryFunctions failed.");
+    }
+    sICUReporterInitialized = true;
+  }
+}
+
+nsresult
+ShutdownXPCOM(nsIServiceManager* aServMgr)
+{
+  // Make sure the hang monitor is enabled for shutdown.
+  HangMonitor::NotifyActivity();
+
+  if (!NS_IsMainThread()) {
+    NS_RUNTIMEABORT("Shutdown on wrong thread");
+  }
+
+  nsresult rv;
+  nsCOMPtr<nsISimpleEnumerator> moduleLoaders;
+
+  // Notify observers of xpcom shutting down
+  {
+    // Block it so that the COMPtr will get deleted before we hit
+    // servicemanager shutdown
+
+    nsCOMPtr<nsIThread> thread = do_GetCurrentThread();
+    if (NS_WARN_IF(!thread)) {
+      return NS_ERROR_UNEXPECTED;
+    }
+
+    RefPtr<nsObserverService> observerService;
+    CallGetService("@mozilla.org/observer-service;1",
+                   (nsObserverService**)getter_AddRefs(observerService));
+
+    if (observerService) {
+      mozilla::KillClearOnShutdown(ShutdownPhase::WillShutdown);
+      observerService->NotifyObservers(nullptr,
+                                       NS_XPCOM_WILL_SHUTDOWN_OBSERVER_ID,
+                                       nullptr);
+
+      nsCOMPtr<nsIServiceManager> mgr;
+      rv = NS_GetServiceManager(getter_AddRefs(mgr));
+      if (NS_SUCCEEDED(rv)) {
+        mozilla::KillClearOnShutdown(ShutdownPhase::Shutdown);
+        observerService->NotifyObservers(mgr, NS_XPCOM_SHUTDOWN_OBSERVER_ID,
+                                         nullptr);
+      }
+    }
+
+    // This must happen after the shutdown of media and widgets, which
+    // are triggered by the NS_XPCOM_SHUTDOWN_OBSERVER_ID notification.
+    NS_ProcessPendingEvents(thread);
+    gfxPlatform::ShutdownLayersIPC();
+    mozilla::dom::VideoDecoderManagerChild::Shutdown();
+
+    mozilla::scache::StartupCache::DeleteSingleton();
+    if (observerService)
+    {
+      mozilla::KillClearOnShutdown(ShutdownPhase::ShutdownThreads);
+      observerService->NotifyObservers(nullptr,
+                                       NS_XPCOM_SHUTDOWN_THREADS_OBSERVER_ID,
+                                       nullptr);
+    }
+
+    gXPCOMThreadsShutDown = true;
+    NS_ProcessPendingEvents(thread);
+
+    // Shutdown the timer thread and all timers that might still be alive before
+    // shutting down the component manager
+    nsTimerImpl::Shutdown();
+
+    NS_ProcessPendingEvents(thread);
+
+    // Shutdown all remaining threads.  This method does not return until
+    // all threads created using the thread manager (with the exception of
+    // the main thread) have exited.
+    nsThreadManager::get().Shutdown();
+
+    NS_ProcessPendingEvents(thread);
+
+    HangMonitor::NotifyActivity();
+
+    // Late-write checks needs to find the profile directory, so it has to
+    // be initialized before mozilla::services::Shutdown or (because of
+    // xpcshell tests replacing the service) modules being unloaded.
+    mozilla::InitLateWriteChecks();
+
+    // We save the "xpcom-shutdown-loaders" observers to notify after
+    // the observerservice is gone.
+    if (observerService) {
+      mozilla::KillClearOnShutdown(ShutdownPhase::ShutdownLoaders);
+      observerService->EnumerateObservers(NS_XPCOM_SHUTDOWN_LOADERS_OBSERVER_ID,
+                                          getter_AddRefs(moduleLoaders));
+
+      observerService->Shutdown();
+    }
+  }
+
+  // Free ClearOnShutdown()'ed smart pointers.  This needs to happen *after*
+  // we've finished notifying observers of XPCOM shutdown, because shutdown
+  // observers themselves might call ClearOnShutdown().
+  mozilla::KillClearOnShutdown(ShutdownPhase::ShutdownFinal);
+
+  // XPCOM is officially in shutdown mode NOW
+  // Set this only after the observers have been notified as this
+  // will cause servicemanager to become inaccessible.
+  mozilla::services::Shutdown();
+
+  // We may have AddRef'd for the caller of NS_InitXPCOM, so release it
+  // here again:
+  NS_IF_RELEASE(aServMgr);
+
+  // Shutdown global servicemanager
+  if (nsComponentManagerImpl::gComponentManager) {
+    nsComponentManagerImpl::gComponentManager->FreeServices();
+  }
+
+  // Release the directory service
+  nsDirectoryService::gService = nullptr;
+
+  free(gGREBinPath);
+  gGREBinPath = nullptr;
+
+  if (moduleLoaders) {
+    bool more;
+    nsCOMPtr<nsISupports> el;
+    while (NS_SUCCEEDED(moduleLoaders->HasMoreElements(&more)) && more) {
+      moduleLoaders->GetNext(getter_AddRefs(el));
+
+      // Don't worry about weak-reference observers here: there is
+      // no reason for weak-ref observers to register for
+      // xpcom-shutdown-loaders
+
+      // FIXME: This can cause harmless writes from sqlite committing
+      // log files. We have to ignore them before we can move
+      // the mozilla::PoisonWrite call before this point. See bug
+      // 834945 for the details.
+      nsCOMPtr<nsIObserver> obs(do_QueryInterface(el));
+      if (obs) {
+        obs->Observe(nullptr, NS_XPCOM_SHUTDOWN_LOADERS_OBSERVER_ID, nullptr);
+      }
+    }
+
+    moduleLoaders = nullptr;
+  }
+
+  bool shutdownCollect;
+#ifdef NS_FREE_PERMANENT_DATA
+  shutdownCollect = true;
+#else
+  shutdownCollect = !!PR_GetEnv("MOZ_CC_RUN_DURING_SHUTDOWN");
+#endif
+  nsCycleCollector_shutdown(shutdownCollect);
+
+  PROFILER_MARKER("Shutdown xpcom");
+  // If we are doing any shutdown checks, poison writes.
+  if (gShutdownChecks != SCM_NOTHING) {
+#ifdef XP_MACOSX
+    mozilla::OnlyReportDirtyWrites();
+#endif /* XP_MACOSX */
+    mozilla::BeginLateWriteChecks();
+  }
+
+  // Shutdown nsLocalFile string conversion
+  NS_ShutdownLocalFile();
+#ifdef XP_UNIX
+  NS_ShutdownNativeCharsetUtils();
+#endif
+
+  // Shutdown xpcom. This will release all loaders and cause others holding
+  // a refcount to the component manager to release it.
+  if (nsComponentManagerImpl::gComponentManager) {
+    rv = (nsComponentManagerImpl::gComponentManager)->Shutdown();
+    NS_ASSERTION(NS_SUCCEEDED(rv), "Component Manager shutdown failed.");
+  } else {
+    NS_WARNING("Component Manager was never created ...");
+  }
+
+#ifdef MOZ_ENABLE_PROFILER_SPS
+  // In optimized builds we don't do shutdown collections by default, so
+  // uncollected (garbage) objects may keep the nsXPConnect singleton alive,
+  // and its XPCJSContext along with it. However, we still destroy various
+  // bits of state in JS_ShutDown(), so we need to make sure the profiler
+  // can't access them when it shuts down. This call nulls out the
+  // JS pseudo-stack's internal reference to the main thread JSContext,
+  // duplicating the call in XPCJSContext::~XPCJSContext() in case that
+  // never fired.
+  if (PseudoStack* stack = mozilla_get_pseudo_stack()) {
+    stack->sampleContext(nullptr);
+  }
+#endif
+
+  if (sInitializedJS) {
+    // Shut down the JS engine.
+    JS_ShutDown();
+    sInitializedJS = false;
+  }
+
+  // Release our own singletons
+  // Do this _after_ shutting down the component manager, because the
+  // JS component loader will use XPConnect to call nsIModule::canUnload,
+  // and that will spin up the InterfaceInfoManager again -- bad mojo
+  XPTInterfaceInfoManager::FreeInterfaceInfoManager();
+
+  // Finally, release the component manager last because it unloads the
+  // libraries:
+  if (nsComponentManagerImpl::gComponentManager) {
+    nsrefcnt cnt;
+    NS_RELEASE2(nsComponentManagerImpl::gComponentManager, cnt);
+    NS_ASSERTION(cnt == 0, "Component Manager being held past XPCOM shutdown.");
+  }
+  nsComponentManagerImpl::gComponentManager = nullptr;
+  nsCategoryManager::Destroy();
+
+  NS_ShutdownAtomTable();
+
+  NS_IF_RELEASE(gDebug);
+
+  delete sIOThread;
+  sIOThread = nullptr;
+
+  delete sMessageLoop;
+  sMessageLoop = nullptr;
+
+  if (sCommandLineWasInitialized) {
+    CommandLine::Terminate();
+    sCommandLineWasInitialized = false;
+  }
+
+  delete sExitManager;
+  sExitManager = nullptr;
+
+  Omnijar::CleanUp();
+
+  HangMonitor::Shutdown();
+
+  delete sMainHangMonitor;
+  sMainHangMonitor = nullptr;
+
+  BackgroundHangMonitor::Shutdown();
+
+  profiler_shutdown();
+
+  NS_LogTerm();
+
+#if defined(MOZ_WIDGET_GONK)
+  // This _exit(0) call is intended to be temporary, to get shutdown leak
+  // checking working on non-B2G platforms.
+  // On debug B2G, the child process crashes very late.  Instead, just
+  // give up so at least we exit cleanly. See bug 1071866.
+  if (XRE_IsContentProcess()) {
+      NS_WARNING("Exiting child process early!");
+      _exit(0);
+  }
+#endif
+
+  return NS_OK;
+}
+
+} // namespace mozilla
diff --git a/xpcom/build/XPCOMModule.inc b/xpcom/build/XPCOMModule.inc
new file mode 100644
index 000000000..5ac2885e2
--- /dev/null
+++ b/xpcom/build/XPCOMModule.inc
@@ -0,0 +1,81 @@
+    COMPONENT_M(MEMORY, nsMemoryImpl::Create, Module::ALLOW_IN_GPU_PROCESS)
+    COMPONENT_M(DEBUG,  nsDebugImpl::Create, Module::ALLOW_IN_GPU_PROCESS)
+    COMPONENT(ERRORSERVICE, nsErrorService::Create)
+
+    COMPONENT_M(CATEGORYMANAGER, nsCategoryManager::Create, Module::ALLOW_IN_GPU_PROCESS)
+
+    COMPONENT(SCRIPTABLEINPUTSTREAM, nsScriptableInputStream::Create)
+    COMPONENT(BINARYINPUTSTREAM, nsBinaryInputStreamConstructor)
+    COMPONENT(BINARYOUTPUTSTREAM, nsBinaryOutputStreamConstructor)
+    COMPONENT(STORAGESTREAM, nsStorageStreamConstructor)
+    COMPONENT(VERSIONCOMPARATOR, nsVersionComparatorImplConstructor)
+    COMPONENT(SCRIPTABLEBASE64ENCODER, nsScriptableBase64EncoderConstructor)
+    COMPONENT(PIPE, nsPipeConstructor)
+
+    COMPONENT(PROPERTIES, nsPropertiesConstructor)
+
+    COMPONENT(PERSISTENTPROPERTIES, nsPersistentProperties::Create)
+
+    COMPONENT(SUPPORTSARRAY, nsSupportsArray::Create)
+    COMPONENT(ARRAY, nsArrayBase::XPCOMConstructor)
+    COMPONENT(CONSOLESERVICE, nsConsoleServiceConstructor)
+    COMPONENT(ATOMSERVICE, nsAtomServiceConstructor)
+    COMPONENT_M(OBSERVERSERVICE, nsObserverService::Create, Module::ALLOW_IN_GPU_PROCESS)
+
+    COMPONENT_M(TIMER, nsTimerConstructor, Module::ALLOW_IN_GPU_PROCESS)
+
+#define COMPONENT_SUPPORTS(TYPE, Type)                                         \
+  COMPONENT(SUPPORTS_##TYPE, nsSupports##Type##Constructor)
+
+    COMPONENT_SUPPORTS(ID, ID)
+    COMPONENT_SUPPORTS(STRING, String)
+    COMPONENT_SUPPORTS(CSTRING, CString)
+    COMPONENT_SUPPORTS(PRBOOL, PRBool)
+    COMPONENT_SUPPORTS(PRUINT8, PRUint8)
+    COMPONENT_SUPPORTS(PRUINT16, PRUint16)
+    COMPONENT_SUPPORTS(PRUINT32, PRUint32)
+    COMPONENT_SUPPORTS(PRUINT64, PRUint64)
+    COMPONENT_SUPPORTS(PRTIME, PRTime)
+    COMPONENT_SUPPORTS(CHAR, Char)
+    COMPONENT_SUPPORTS(PRINT16, PRInt16)
+    COMPONENT_SUPPORTS(PRINT32, PRInt32)
+    COMPONENT_SUPPORTS(PRINT64, PRInt64)
+    COMPONENT_SUPPORTS(FLOAT, Float)
+    COMPONENT_SUPPORTS(DOUBLE, Double)
+    COMPONENT_SUPPORTS(VOID, Void)
+    COMPONENT_SUPPORTS(INTERFACE_POINTER, InterfacePointer)
+
+#undef COMPONENT_SUPPORTS
+    COMPONENT(LOCAL_FILE, nsLocalFile::nsLocalFileConstructor)
+    COMPONENT(DIRECTORY_SERVICE, nsDirectoryService::Create)
+    COMPONENT(PROCESS, nsProcessConstructor)
+    COMPONENT(ENVIRONMENT, nsEnvironment::Create)
+
+    COMPONENT(THREADMANAGER, nsThreadManagerGetSingleton)
+    COMPONENT_M(THREADPOOL, nsThreadPoolConstructor, Module::ALLOW_IN_GPU_PROCESS)
+
+    COMPONENT(STRINGINPUTSTREAM, nsStringInputStreamConstructor)
+    COMPONENT(MULTIPLEXINPUTSTREAM, nsMultiplexInputStreamConstructor)
+
+    COMPONENT(VARIANT, nsVariantCCConstructor)
+    COMPONENT(INTERFACEINFOMANAGER_SERVICE, nsXPTIInterfaceInfoManagerGetSingleton)
+
+    COMPONENT(HASH_PROPERTY_BAG, nsHashPropertyBagCCConstructor)
+
+    COMPONENT(UUID_GENERATOR, nsUUIDGeneratorConstructor)
+
+#if defined(XP_WIN)
+    COMPONENT(WINDOWSREGKEY, nsWindowsRegKeyConstructor)
+#endif
+
+#if defined(MOZ_WIDGET_COCOA)
+    COMPONENT(MACUTILSIMPL, nsMacUtilsImplConstructor)
+#endif
+
+    COMPONENT(SYSTEMINFO, nsSystemInfoConstructor)
+    COMPONENT(MEMORY_REPORTER_MANAGER, nsMemoryReporterManagerConstructor)
+    COMPONENT(MEMORY_INFO_DUMPER, nsMemoryInfoDumperConstructor)
+    COMPONENT(IOUTIL, nsIOUtilConstructor)
+    COMPONENT(CYCLE_COLLECTOR_LOGGER, nsCycleCollectorLoggerConstructor)
+    COMPONENT(MESSAGE_LOOP, nsMessageLoopConstructor)
+    COMPONENT(STATUS_REPORTER_MANAGER, nsStatusReporterManagerConstructor)
diff --git a/xpcom/build/XREChildData.h b/xpcom/build/XREChildData.h
new file mode 100644
index 000000000..487fede94
--- /dev/null
+++ b/xpcom/build/XREChildData.h
@@ -0,0 +1,51 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef XREChildData_h
+#define XREChildData_h
+
+#include "mozilla/UniquePtr.h"
+
+#if defined(XP_WIN) && defined(MOZ_SANDBOX)
+#include "mozilla/sandboxing/loggingTypes.h"
+
+namespace sandbox {
+class TargetServices;
+}
+#endif
+
+namespace mozilla {
+namespace gmp {
+class GMPLoader;
+}
+}
+
+/**
+ * Data needed to start a child process.
+ */
+struct XREChildData
+{
+#if !defined(MOZ_WIDGET_ANDROID) && !defined(MOZ_WIDGET_GONK)
+  /**
+   * Used to load the GMP binary.
+   */
+  mozilla::UniquePtr<mozilla::gmp::GMPLoader> gmpLoader;
+#endif
+
+#if defined(XP_WIN) && defined(MOZ_SANDBOX)
+  /**
+   * Chromium sandbox TargetServices.
+   */
+  sandbox::TargetServices* sandboxTargetServices = nullptr;
+
+  /**
+   * Function to provide a logging function to the chromium sandbox code.
+   */
+  mozilla::sandboxing::ProvideLogFunctionCb ProvideLogFunction = nullptr;
+#endif
+};
+
+#endif // XREChildData_h
diff --git a/xpcom/build/XREShellData.h b/xpcom/build/XREShellData.h
new file mode 100644
index 000000000..11bc162d9
--- /dev/null
+++ b/xpcom/build/XREShellData.h
@@ -0,0 +1,29 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef XREShellData_h
+#define XREShellData_h
+
+#if defined(XP_WIN) && defined(MOZ_SANDBOX)
+namespace sandbox {
+class BrokerServices;
+}
+#endif
+
+/**
+ * Data needed by XRE_XPCShellMain.
+ */
+struct XREShellData
+{
+#if defined(XP_WIN) && defined(MOZ_SANDBOX)
+  /**
+   * Chromium sandbox BrokerServices.
+   */
+  sandbox::BrokerServices* sandboxBrokerServices;
+#endif
+};
+
+#endif // XREShellData_h
diff --git a/xpcom/build/mach_override.c b/xpcom/build/mach_override.c
new file mode 100644
index 000000000..9e4940d29
--- /dev/null
+++ b/xpcom/build/mach_override.c
@@ -0,0 +1,789 @@
+// Copied from upstream at revision 195c13743fe0ebc658714e2a9567d86529f20443.
+// mach_override.c semver:1.2.0
+//   Copyright (c) 2003-2012 Jonathan 'Wolf' Rentzsch: http://rentzsch.com
+//   Some rights reserved: http://opensource.org/licenses/mit
+//   https://github.com/rentzsch/mach_override
+
+#include "mach_override.h"
+
+#include <mach-o/dyld.h>
+#include <mach/mach_host.h>
+#include <mach/mach_init.h>
+#include <mach/vm_map.h>
+#include <sys/mman.h>
+
+#include <CoreServices/CoreServices.h>
+
+/**************************
+*	
+*	Constants
+*	
+**************************/
+#pragma mark	-
+#pragma mark	(Constants)
+
+#define kPageSize 4096
+#if defined(__ppc__) || defined(__POWERPC__)
+
+long kIslandTemplate[] = {
+	0x9001FFFC,	//	stw		r0,-4(SP)
+	0x3C00DEAD,	//	lis		r0,0xDEAD
+	0x6000BEEF,	//	ori		r0,r0,0xBEEF
+	0x7C0903A6,	//	mtctr	r0
+	0x8001FFFC,	//	lwz		r0,-4(SP)
+	0x60000000,	//	nop		; optionally replaced
+	0x4E800420 	//	bctr
+};
+
+#define kAddressHi			3
+#define kAddressLo			5
+#define kInstructionHi		10
+#define kInstructionLo		11
+
+#elif defined(__i386__) 
+
+#define kOriginalInstructionsSize 16
+// On X86 we migh need to instert an add with a 32 bit immediate after the
+// original instructions.
+#define kMaxFixupSizeIncrease 5
+
+unsigned char kIslandTemplate[] = {
+	// kOriginalInstructionsSize nop instructions so that we 
+	// should have enough space to host original instructions 
+	0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 
+	0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
+	// Now the real jump instruction
+	0xE9, 0xEF, 0xBE, 0xAD, 0xDE
+};
+
+#define kInstructions	0
+#define kJumpAddress    kInstructions + kOriginalInstructionsSize + 1
+#elif defined(__x86_64__)
+
+#define kOriginalInstructionsSize 32
+// On X86-64 we never need to instert a new instruction.
+#define kMaxFixupSizeIncrease 0
+
+#define kJumpAddress    kOriginalInstructionsSize + 6
+
+unsigned char kIslandTemplate[] = {
+	// kOriginalInstructionsSize nop instructions so that we 
+	// should have enough space to host original instructions 
+	0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 
+	0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
+	0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 
+	0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
+	// Now the real jump instruction
+	0xFF, 0x25, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00
+};
+
+#endif
+
+/**************************
+*	
+*	Data Types
+*	
+**************************/
+#pragma mark	-
+#pragma mark	(Data Types)
+
+typedef	struct	{
+	char	instructions[sizeof(kIslandTemplate)];
+}	BranchIsland;
+
+/**************************
+*	
+*	Funky Protos
+*	
+**************************/
+#pragma mark	-
+#pragma mark	(Funky Protos)
+
+static mach_error_t
+allocateBranchIsland(
+		BranchIsland	**island,
+		void *originalFunctionAddress);
+
+	mach_error_t
+freeBranchIsland(
+		BranchIsland	*island );
+
+#if defined(__ppc__) || defined(__POWERPC__)
+	mach_error_t
+setBranchIslandTarget(
+		BranchIsland	*island,
+		const void		*branchTo,
+		long			instruction );
+#endif 
+
+#if defined(__i386__) || defined(__x86_64__)
+mach_error_t
+setBranchIslandTarget_i386(
+						   BranchIsland	*island,
+						   const void		*branchTo,
+						   char*			instructions );
+void 
+atomic_mov64(
+		uint64_t *targetAddress,
+		uint64_t value );
+
+	static Boolean 
+eatKnownInstructions( 
+	unsigned char	*code, 
+	uint64_t		*newInstruction,
+	int				*howManyEaten, 
+	char			*originalInstructions,
+	int				*originalInstructionCount, 
+	uint8_t			*originalInstructionSizes );
+
+	static void
+fixupInstructions(
+    uint32_t		offset,
+    void		*instructionsToFix,
+	int			instructionCount,
+	uint8_t		*instructionSizes );
+#endif
+
+/*******************************************************************************
+*	
+*	Interface
+*	
+*******************************************************************************/
+#pragma mark	-
+#pragma mark	(Interface)
+
+#if defined(__i386__) || defined(__x86_64__)
+mach_error_t makeIslandExecutable(void *address) {
+	mach_error_t err = err_none;
+    uintptr_t page = (uintptr_t)address & ~(uintptr_t)(kPageSize-1);
+    int e = err_none;
+    e |= mprotect((void *)page, kPageSize, PROT_EXEC | PROT_READ | PROT_WRITE);
+    e |= msync((void *)page, kPageSize, MS_INVALIDATE );
+    if (e) {
+        err = err_cannot_override;
+    }
+    return err;
+}
+#endif
+
+    mach_error_t
+mach_override_ptr(
+	void *originalFunctionAddress,
+    const void *overrideFunctionAddress,
+    void **originalFunctionReentryIsland )
+{
+	assert( originalFunctionAddress );
+	assert( overrideFunctionAddress );
+	
+	// this addresses overriding such functions as AudioOutputUnitStart()
+	// test with modified DefaultOutputUnit project
+#if defined(__x86_64__)
+    for(;;){
+        if(*(uint16_t*)originalFunctionAddress==0x25FF)    // jmp qword near [rip+0x????????]
+            originalFunctionAddress=*(void**)((char*)originalFunctionAddress+6+*(int32_t *)((uint16_t*)originalFunctionAddress+1));
+        else break;
+    }
+#elif defined(__i386__)
+    for(;;){
+        if(*(uint16_t*)originalFunctionAddress==0x25FF)    // jmp *0x????????
+            originalFunctionAddress=**(void***)((uint16_t*)originalFunctionAddress+1);
+        else break;
+    }
+#endif
+
+	long	*originalFunctionPtr = (long*) originalFunctionAddress;
+	mach_error_t	err = err_none;
+	
+#if defined(__ppc__) || defined(__POWERPC__)
+	//	Ensure first instruction isn't 'mfctr'.
+	#define	kMFCTRMask			0xfc1fffff
+	#define	kMFCTRInstruction	0x7c0903a6
+	
+	long	originalInstruction = *originalFunctionPtr;
+	if( !err && ((originalInstruction & kMFCTRMask) == kMFCTRInstruction) )
+		err = err_cannot_override;
+#elif defined(__i386__) || defined(__x86_64__)
+	int eatenCount = 0;
+	int originalInstructionCount = 0;
+	char originalInstructions[kOriginalInstructionsSize];
+	uint8_t originalInstructionSizes[kOriginalInstructionsSize];
+	uint64_t jumpRelativeInstruction = 0; // JMP
+
+	Boolean overridePossible = eatKnownInstructions ((unsigned char *)originalFunctionPtr, 
+										&jumpRelativeInstruction, &eatenCount, 
+										originalInstructions, &originalInstructionCount, 
+										originalInstructionSizes );
+	if (eatenCount + kMaxFixupSizeIncrease > kOriginalInstructionsSize) {
+		//printf ("Too many instructions eaten\n");
+		overridePossible = false;
+	}
+	if (!overridePossible) err = err_cannot_override;
+	if (err) fprintf(stderr, "err = %x %s:%d\n", err, __FILE__, __LINE__);
+#endif
+	
+	//	Make the original function implementation writable.
+	if( !err ) {
+		err = vm_protect( mach_task_self(),
+				(vm_address_t) originalFunctionPtr, 8, false,
+				(VM_PROT_ALL | VM_PROT_COPY) );
+		if( err )
+			err = vm_protect( mach_task_self(),
+					(vm_address_t) originalFunctionPtr, 8, false,
+					(VM_PROT_DEFAULT | VM_PROT_COPY) );
+	}
+	if (err) fprintf(stderr, "err = %x %s:%d\n", err, __FILE__, __LINE__);
+	
+	//	Allocate and target the escape island to the overriding function.
+	BranchIsland	*escapeIsland = NULL;
+	if( !err )	
+		err = allocateBranchIsland( &escapeIsland, originalFunctionAddress );
+		if (err) fprintf(stderr, "err = %x %s:%d\n", err, __FILE__, __LINE__);
+
+	
+#if defined(__ppc__) || defined(__POWERPC__)
+	if( !err )
+		err = setBranchIslandTarget( escapeIsland, overrideFunctionAddress, 0 );
+	
+	//	Build the branch absolute instruction to the escape island.
+	long	branchAbsoluteInstruction = 0; // Set to 0 just to silence warning.
+	if( !err ) {
+		long escapeIslandAddress = ((long) escapeIsland) & 0x3FFFFFF;
+		branchAbsoluteInstruction = 0x48000002 | escapeIslandAddress;
+	}
+#elif defined(__i386__) || defined(__x86_64__)
+        if (err) fprintf(stderr, "err = %x %s:%d\n", err, __FILE__, __LINE__);
+
+	if( !err )
+		err = setBranchIslandTarget_i386( escapeIsland, overrideFunctionAddress, 0 );
+ 
+	if (err) fprintf(stderr, "err = %x %s:%d\n", err, __FILE__, __LINE__);
+	// Build the jump relative instruction to the escape island
+#endif
+
+
+#if defined(__i386__) || defined(__x86_64__)
+	if (!err) {
+		uint32_t addressOffset = ((char*)escapeIsland - (char*)originalFunctionPtr - 5);
+		addressOffset = OSSwapInt32(addressOffset);
+		
+		jumpRelativeInstruction |= 0xE900000000000000LL; 
+		jumpRelativeInstruction |= ((uint64_t)addressOffset & 0xffffffff) << 24;
+		jumpRelativeInstruction = OSSwapInt64(jumpRelativeInstruction);		
+	}
+#endif
+	
+	//	Optionally allocate & return the reentry island. This may contain relocated
+	//  jmp instructions and so has all the same addressing reachability requirements
+	//  the escape island has to the original function, except the escape island is
+	//  technically our original function.
+	BranchIsland	*reentryIsland = NULL;
+	if( !err && originalFunctionReentryIsland ) {
+		err = allocateBranchIsland( &reentryIsland, escapeIsland);
+		if( !err )
+			*originalFunctionReentryIsland = reentryIsland;
+	}
+	
+#if defined(__ppc__) || defined(__POWERPC__)	
+	//	Atomically:
+	//	o If the reentry island was allocated:
+	//		o Insert the original instruction into the reentry island.
+	//		o Target the reentry island at the 2nd instruction of the
+	//		  original function.
+	//	o Replace the original instruction with the branch absolute.
+	if( !err ) {
+		int escapeIslandEngaged = false;
+		do {
+			if( reentryIsland )
+				err = setBranchIslandTarget( reentryIsland,
+						(void*) (originalFunctionPtr+1), originalInstruction );
+			if( !err ) {
+				escapeIslandEngaged = CompareAndSwap( originalInstruction,
+										branchAbsoluteInstruction,
+										(UInt32*)originalFunctionPtr );
+				if( !escapeIslandEngaged ) {
+					//	Someone replaced the instruction out from under us,
+					//	re-read the instruction, make sure it's still not
+					//	'mfctr' and try again.
+					originalInstruction = *originalFunctionPtr;
+					if( (originalInstruction & kMFCTRMask) == kMFCTRInstruction)
+						err = err_cannot_override;
+				}
+			}
+		} while( !err && !escapeIslandEngaged );
+	}
+#elif defined(__i386__) || defined(__x86_64__)
+	// Atomically:
+	//	o If the reentry island was allocated:
+	//		o Insert the original instructions into the reentry island.
+	//		o Target the reentry island at the first non-replaced 
+	//        instruction of the original function.
+	//	o Replace the original first instructions with the jump relative.
+	//
+	// Note that on i386, we do not support someone else changing the code under our feet
+	if ( !err ) {
+		uint32_t offset = (uintptr_t)originalFunctionPtr - (uintptr_t)reentryIsland;
+		fixupInstructions(offset, originalInstructions,
+					originalInstructionCount, originalInstructionSizes );
+	
+		if( reentryIsland )
+			err = setBranchIslandTarget_i386( reentryIsland,
+										 (void*) ((char *)originalFunctionPtr+eatenCount), originalInstructions );
+		// try making islands executable before planting the jmp
+#if defined(__x86_64__) || defined(__i386__)
+        if( !err )
+            err = makeIslandExecutable(escapeIsland);
+        if( !err && reentryIsland )
+            err = makeIslandExecutable(reentryIsland);
+#endif
+		if ( !err )
+			atomic_mov64((uint64_t *)originalFunctionPtr, jumpRelativeInstruction);
+	}
+#endif
+	
+	//	Clean up on error.
+	if( err ) {
+		if( reentryIsland )
+			freeBranchIsland( reentryIsland );
+		if( escapeIsland )
+			freeBranchIsland( escapeIsland );
+	}
+
+	return err;
+}
+
+/*******************************************************************************
+*	
+*	Implementation
+*	
+*******************************************************************************/
+#pragma mark	-
+#pragma mark	(Implementation)
+
+static bool jump_in_range(intptr_t from, intptr_t to) {
+  intptr_t field_value = to - from - 5;
+  int32_t field_value_32 = field_value;
+  return field_value == field_value_32;
+}
+
+/*******************************************************************************
+	Implementation: Allocates memory for a branch island.
+	
+	@param	island			<-	The allocated island.
+	@result					<-	mach_error_t
+
+	***************************************************************************/
+
+static mach_error_t
+allocateBranchIslandAux(
+		BranchIsland	**island,
+		void *originalFunctionAddress,
+		bool forward)
+{
+	assert( island );
+	assert( sizeof( BranchIsland ) <= kPageSize );
+
+	vm_map_t task_self = mach_task_self();
+	vm_address_t original_address = (vm_address_t) originalFunctionAddress;
+	vm_address_t address = original_address;
+
+	for (;;) {
+		vm_size_t vmsize = 0;
+		memory_object_name_t object = 0;
+		kern_return_t kr = 0;
+		vm_region_flavor_t flavor = VM_REGION_BASIC_INFO;
+		// Find the region the address is in.
+#if __WORDSIZE == 32
+		vm_region_basic_info_data_t info;
+		mach_msg_type_number_t info_count = VM_REGION_BASIC_INFO_COUNT;
+		kr = vm_region(task_self, &address, &vmsize, flavor,
+			       (vm_region_info_t)&info, &info_count, &object);
+#else
+		vm_region_basic_info_data_64_t info;
+		mach_msg_type_number_t info_count = VM_REGION_BASIC_INFO_COUNT_64;
+		kr = vm_region_64(task_self, &address, &vmsize, flavor,
+				  (vm_region_info_t)&info, &info_count, &object);
+#endif
+		if (kr != KERN_SUCCESS)
+			return kr;
+		assert((address & (kPageSize - 1)) == 0);
+
+		// Go to the first page before or after this region
+		vm_address_t new_address = forward ? address + vmsize : address - kPageSize;
+#if __WORDSIZE == 64
+		if(!jump_in_range(original_address, new_address))
+			break;
+#endif
+		address = new_address;
+
+		// Try to allocate this page.
+		kr = vm_allocate(task_self, &address, kPageSize, 0);
+		if (kr == KERN_SUCCESS) {
+			*island = (BranchIsland*) address;
+			return err_none;
+		}
+		if (kr != KERN_NO_SPACE)
+			return kr;
+	}
+
+	return KERN_NO_SPACE;
+}
+
+static mach_error_t
+allocateBranchIsland(
+		BranchIsland	**island,
+		void *originalFunctionAddress)
+{
+  mach_error_t err =
+    allocateBranchIslandAux(island, originalFunctionAddress, true);
+  if (!err)
+    return err;
+  return allocateBranchIslandAux(island, originalFunctionAddress, false);
+}
+
+
+/*******************************************************************************
+	Implementation: Deallocates memory for a branch island.
+	
+	@param	island	->	The island to deallocate.
+	@result			<-	mach_error_t
+
+	***************************************************************************/
+
+	mach_error_t
+freeBranchIsland(
+		BranchIsland	*island )
+{
+	assert( island );
+	assert( (*(long*)&island->instructions[0]) == kIslandTemplate[0] );
+	assert( sizeof( BranchIsland ) <= kPageSize );
+	return vm_deallocate( mach_task_self(), (vm_address_t) island,
+			      kPageSize );
+}
+
+/*******************************************************************************
+	Implementation: Sets the branch island's target, with an optional
+	instruction.
+	
+	@param	island		->	The branch island to insert target into.
+	@param	branchTo	->	The address of the target.
+	@param	instruction	->	Optional instruction to execute prior to branch. Set
+							to zero for nop.
+	@result				<-	mach_error_t
+
+	***************************************************************************/
+#if defined(__ppc__) || defined(__POWERPC__)
+	mach_error_t
+setBranchIslandTarget(
+		BranchIsland	*island,
+		const void		*branchTo,
+		long			instruction )
+{
+	//	Copy over the template code.
+    bcopy( kIslandTemplate, island->instructions, sizeof( kIslandTemplate ) );
+    
+    //	Fill in the address.
+    ((short*)island->instructions)[kAddressLo] = ((long) branchTo) & 0x0000FFFF;
+    ((short*)island->instructions)[kAddressHi]
+    	= (((long) branchTo) >> 16) & 0x0000FFFF;
+    
+    //	Fill in the (optional) instuction.
+    if( instruction != 0 ) {
+        ((short*)island->instructions)[kInstructionLo]
+        	= instruction & 0x0000FFFF;
+        ((short*)island->instructions)[kInstructionHi]
+        	= (instruction >> 16) & 0x0000FFFF;
+    }
+    
+    //MakeDataExecutable( island->instructions, sizeof( kIslandTemplate ) );
+	msync( island->instructions, sizeof( kIslandTemplate ), MS_INVALIDATE );
+    
+    return err_none;
+}
+#endif 
+
+#if defined(__i386__)
+	mach_error_t
+setBranchIslandTarget_i386(
+	BranchIsland	*island,
+	const void		*branchTo,
+	char*			instructions )
+{
+
+	//	Copy over the template code.
+    bcopy( kIslandTemplate, island->instructions, sizeof( kIslandTemplate ) );
+
+	// copy original instructions
+	if (instructions) {
+		bcopy (instructions, island->instructions + kInstructions, kOriginalInstructionsSize);
+	}
+	
+    // Fill in the address.
+    int32_t addressOffset = (char *)branchTo - (island->instructions + kJumpAddress + 4);
+    *((int32_t *)(island->instructions + kJumpAddress)) = addressOffset; 
+
+    msync( island->instructions, sizeof( kIslandTemplate ), MS_INVALIDATE );
+    return err_none;
+}
+
+#elif defined(__x86_64__)
+mach_error_t
+setBranchIslandTarget_i386(
+        BranchIsland	*island,
+        const void		*branchTo,
+        char*			instructions )
+{
+    // Copy over the template code.
+    bcopy( kIslandTemplate, island->instructions, sizeof( kIslandTemplate ) );
+
+    // Copy original instructions.
+    if (instructions) {
+        bcopy (instructions, island->instructions, kOriginalInstructionsSize);
+    }
+
+    //	Fill in the address.
+    *((uint64_t *)(island->instructions + kJumpAddress)) = (uint64_t)branchTo; 
+    msync( island->instructions, sizeof( kIslandTemplate ), MS_INVALIDATE );
+
+    return err_none;
+}
+#endif
+
+
+#if defined(__i386__) || defined(__x86_64__)
+// simplistic instruction matching
+typedef struct {
+	unsigned int length; // max 15
+	unsigned char mask[15]; // sequence of bytes in memory order
+	unsigned char constraint[15]; // sequence of bytes in memory order
+}	AsmInstructionMatch;
+
+#if defined(__i386__)
+static AsmInstructionMatch possibleInstructions[] = {
+	{ 0x5, {0xFF, 0x00, 0x00, 0x00, 0x00}, {0xE9, 0x00, 0x00, 0x00, 0x00} },	// jmp 0x????????
+	{ 0x5, {0xFF, 0xFF, 0xFF, 0xFF, 0xFF}, {0x55, 0x89, 0xe5, 0xc9, 0xc3} },	// push %ebp; mov %esp,%ebp; leave; ret
+	{ 0x1, {0xFF}, {0x90} },							// nop
+	{ 0x1, {0xFF}, {0x55} },							// push %esp
+	{ 0x2, {0xFF, 0xFF}, {0x89, 0xE5} },				                // mov %esp,%ebp
+	{ 0x1, {0xFF}, {0x53} },							// push %ebx
+	{ 0x3, {0xFF, 0xFF, 0x00}, {0x83, 0xEC, 0x00} },	                        // sub 0x??, %esp
+	{ 0x6, {0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00}, {0x81, 0xEC, 0x00, 0x00, 0x00, 0x00} },	// sub 0x??, %esp with 32bit immediate
+	{ 0x1, {0xFF}, {0x57} },							// push %edi
+	{ 0x1, {0xFF}, {0x56} },							// push %esi
+	{ 0x2, {0xFF, 0xFF}, {0x31, 0xC0} },						// xor %eax, %eax
+	{ 0x3, {0xFF, 0x4F, 0x00}, {0x8B, 0x45, 0x00} },  // mov $imm(%ebp), %reg
+	{ 0x3, {0xFF, 0x4C, 0x00}, {0x8B, 0x40, 0x00} },  // mov $imm(%eax-%edx), %reg
+	{ 0x4, {0xFF, 0xFF, 0xFF, 0x00}, {0x8B, 0x4C, 0x24, 0x00} },  // mov $imm(%esp), %ecx
+	{ 0x5, {0xFF, 0x00, 0x00, 0x00, 0x00}, {0xB8, 0x00, 0x00, 0x00, 0x00} },	// mov $imm, %eax
+	{ 0x6, {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF}, {0xE8, 0x00, 0x00, 0x00, 0x00, 0x58} },	// call $imm; pop %eax
+	{ 0x0 }
+};
+#elif defined(__x86_64__)
+static AsmInstructionMatch possibleInstructions[] = {
+	{ 0x5, {0xFF, 0x00, 0x00, 0x00, 0x00}, {0xE9, 0x00, 0x00, 0x00, 0x00} },	// jmp 0x????????
+	{ 0x1, {0xFF}, {0x90} },							// nop
+	{ 0x1, {0xF8}, {0x50} },							// push %rX
+	{ 0x3, {0xFF, 0xFF, 0xFF}, {0x48, 0x89, 0xE5} },				// mov %rsp,%rbp
+	{ 0x4, {0xFF, 0xFF, 0xFF, 0x00}, {0x48, 0x83, 0xEC, 0x00} },	                // sub 0x??, %rsp
+	{ 0x4, {0xFB, 0xFF, 0x00, 0x00}, {0x48, 0x89, 0x00, 0x00} },	                // move onto rbp
+	{ 0x4, {0xFF, 0xFF, 0xFF, 0xFF}, {0x40, 0x0f, 0xbe, 0xce} },			// movsbl %sil, %ecx
+	{ 0x2, {0xFF, 0x00}, {0x41, 0x00} },						// push %rXX
+	{ 0x2, {0xFF, 0x00}, {0x85, 0x00} },						// test %rX,%rX
+	{ 0x5, {0xF8, 0x00, 0x00, 0x00, 0x00}, {0xB8, 0x00, 0x00, 0x00, 0x00} },   // mov $imm, %reg
+	{ 0x3, {0xFF, 0xFF, 0x00}, {0xFF, 0x77, 0x00} },  // pushq $imm(%rdi)
+	{ 0x2, {0xFF, 0xFF}, {0x31, 0xC0} },						// xor %eax, %eax
+	{ 0x2, {0xFF, 0xFF}, {0x89, 0xF8} },			// mov %edi, %eax
+
+	//leaq offset(%rip),%rax
+	{ 0x7, {0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00}, {0x48, 0x8d, 0x05, 0x00, 0x00, 0x00, 0x00} },
+
+	{ 0x0 }
+};
+#endif
+
+static Boolean codeMatchesInstruction(unsigned char *code, AsmInstructionMatch* instruction) 
+{
+	Boolean match = true;
+	
+	size_t i;
+	for (i=0; i<instruction->length; i++) {
+		unsigned char mask = instruction->mask[i];
+		unsigned char constraint = instruction->constraint[i];
+		unsigned char codeValue = code[i];
+				
+		match = ((codeValue & mask) == constraint);
+		if (!match) break;
+	}
+	
+	return match;
+}
+
+#if defined(__i386__) || defined(__x86_64__)
+	static Boolean 
+eatKnownInstructions( 
+	unsigned char	*code, 
+	uint64_t		*newInstruction,
+	int				*howManyEaten, 
+	char			*originalInstructions,
+	int				*originalInstructionCount, 
+	uint8_t			*originalInstructionSizes )
+{
+	Boolean allInstructionsKnown = true;
+	int totalEaten = 0;
+	unsigned char* ptr = code;
+	int remainsToEat = 5; // a JMP instruction takes 5 bytes
+	int instructionIndex = 0;
+	
+	if (howManyEaten) *howManyEaten = 0;
+	if (originalInstructionCount) *originalInstructionCount = 0;
+	while (remainsToEat > 0) {
+		Boolean curInstructionKnown = false;
+		
+		// See if instruction matches one  we know
+		AsmInstructionMatch* curInstr = possibleInstructions;
+		do { 
+			if ((curInstructionKnown = codeMatchesInstruction(ptr, curInstr))) break;
+			curInstr++;
+		} while (curInstr->length > 0);
+		
+		// if all instruction matches failed, we don't know current instruction then, stop here
+		if (!curInstructionKnown) { 
+			allInstructionsKnown = false;
+			fprintf(stderr, "mach_override: some instructions unknown! Need to update mach_override.c\n");
+			break;
+		}
+		
+		// At this point, we've matched curInstr
+		int eaten = curInstr->length;
+		ptr += eaten;
+		remainsToEat -= eaten;
+		totalEaten += eaten;
+		
+		if (originalInstructionSizes) originalInstructionSizes[instructionIndex] = eaten;
+		instructionIndex += 1;
+		if (originalInstructionCount) *originalInstructionCount = instructionIndex;
+	}
+
+
+	if (howManyEaten) *howManyEaten = totalEaten;
+
+	if (originalInstructions) {
+		Boolean enoughSpaceForOriginalInstructions = (totalEaten < kOriginalInstructionsSize);
+		
+		if (enoughSpaceForOriginalInstructions) {
+			memset(originalInstructions, 0x90 /* NOP */, kOriginalInstructionsSize); // fill instructions with NOP
+			bcopy(code, originalInstructions, totalEaten);
+		} else {
+			// printf ("Not enough space in island to store original instructions. Adapt the island definition and kOriginalInstructionsSize\n");
+			return false;
+		}
+	}
+	
+	if (allInstructionsKnown) {
+		// save last 3 bytes of first 64bits of codre we'll replace
+		uint64_t currentFirst64BitsOfCode = *((uint64_t *)code);
+		currentFirst64BitsOfCode = OSSwapInt64(currentFirst64BitsOfCode); // back to memory representation
+		currentFirst64BitsOfCode &= 0x0000000000FFFFFFLL; 
+		
+		// keep only last 3 instructions bytes, first 5 will be replaced by JMP instr
+		*newInstruction &= 0xFFFFFFFFFF000000LL; // clear last 3 bytes
+		*newInstruction |= (currentFirst64BitsOfCode & 0x0000000000FFFFFFLL); // set last 3 bytes
+	}
+
+	return allInstructionsKnown;
+}
+
+	static void
+fixupInstructions(
+	uint32_t	offset,
+    void		*instructionsToFix,
+	int			instructionCount,
+	uint8_t		*instructionSizes )
+{
+	// The start of "leaq offset(%rip),%rax"
+	static const uint8_t LeaqHeader[] = {0x48, 0x8d, 0x05};
+
+	int	index;
+	for (index = 0;index < instructionCount;index += 1)
+	{
+		if (*(uint8_t*)instructionsToFix == 0xE9) // 32-bit jump relative
+		{
+			uint32_t *jumpOffsetPtr = (uint32_t*)((uintptr_t)instructionsToFix + 1);
+			*jumpOffsetPtr += offset;
+		}
+
+		// leaq offset(%rip),%rax
+		if (memcmp(instructionsToFix, LeaqHeader, 3) == 0) {
+			uint32_t *LeaqOffsetPtr = (uint32_t*)((uintptr_t)instructionsToFix + 3);
+			*LeaqOffsetPtr += offset;
+		}
+
+		// 32-bit call relative to the next addr; pop %eax
+		if (*(uint8_t*)instructionsToFix == 0xE8)
+		{
+			// Just this call is larger than the jump we use, so we
+			// know this is the last instruction.
+			assert(index == (instructionCount - 1));
+			assert(instructionSizes[index] == 6);
+
+                        // Insert "addl $offset, %eax" in the end so that when
+                        // we jump to the rest of the function %eax has the
+                        // value it would have if eip had been pushed by the
+                        // call in its original position.
+			uint8_t *op = instructionsToFix;
+			op += 6;
+			*op = 0x05; // addl
+			uint32_t *addImmPtr = (uint32_t*)(op + 1);
+			*addImmPtr = offset;
+		}
+
+		instructionsToFix = (void*)((uintptr_t)instructionsToFix + instructionSizes[index]);
+    }
+}
+#endif
+
+#if defined(__i386__)
+__asm(
+			".text;"
+			".align 2, 0x90;"
+			"_atomic_mov64:;"
+			"	pushl %ebp;"
+			"	movl %esp, %ebp;"
+			"	pushl %esi;"
+			"	pushl %ebx;"
+			"	pushl %ecx;"
+			"	pushl %eax;"
+			"	pushl %edx;"
+	
+			// atomic push of value to an address
+			// we use cmpxchg8b, which compares content of an address with 
+			// edx:eax. If they are equal, it atomically puts 64bit value 
+			// ecx:ebx in address. 
+			// We thus put contents of address in edx:eax to force ecx:ebx
+			// in address
+			"	mov		8(%ebp), %esi;"  // esi contains target address
+			"	mov		12(%ebp), %ebx;"
+			"	mov		16(%ebp), %ecx;" // ecx:ebx now contains value to put in target address
+			"	mov		(%esi), %eax;"
+			"	mov		4(%esi), %edx;"  // edx:eax now contains value currently contained in target address
+			"	lock; cmpxchg8b	(%esi);" // atomic move.
+			
+			// restore registers
+			"	popl %edx;"
+			"	popl %eax;"
+			"	popl %ecx;"
+			"	popl %ebx;"
+			"	popl %esi;"
+			"	popl %ebp;"
+			"	ret"
+);
+#elif defined(__x86_64__)
+void atomic_mov64(
+		uint64_t *targetAddress,
+		uint64_t value )
+{
+    *targetAddress = value;
+}
+#endif
+#endif
diff --git a/xpcom/build/mach_override.h b/xpcom/build/mach_override.h
new file mode 100644
index 000000000..d9be988a3
--- /dev/null
+++ b/xpcom/build/mach_override.h
@@ -0,0 +1,121 @@
+/*******************************************************************************
+	mach_override.h
+		Copyright (c) 2003-2009 Jonathan 'Wolf' Rentzsch: <http://rentzsch.com>
+		Some rights reserved: <http://opensource.org/licenses/mit-license.php>
+
+	***************************************************************************/
+
+/***************************************************************************//**
+	@mainpage	mach_override
+	@author		Jonathan 'Wolf' Rentzsch: <http://rentzsch.com>
+	
+	This package, coded in C to the Mach API, allows you to override ("patch")
+	program- and system-supplied functions at runtime. You can fully replace
+	functions with your implementations, or merely head- or tail-patch the
+	original implementations.
+	
+	Use it by #include'ing mach_override.h from your .c, .m or .mm file(s).
+	
+	@todo	Discontinue use of Carbon's MakeDataExecutable() and
+			CompareAndSwap() calls and start using the Mach equivalents, if they
+			exist. If they don't, write them and roll them in. That way, this
+			code will be pure Mach, which will make it easier to use everywhere.
+			Update: MakeDataExecutable() has been replaced by
+			msync(MS_INVALIDATE). There is an OSCompareAndSwap in libkern, but
+			I'm currently unsure if I can link against it. May have to roll in
+			my own version...
+	@todo	Stop using an entire 4K high-allocated VM page per 28-byte escape
+			branch island. Done right, this will dramatically speed up escape
+			island allocations when they number over 250. Then again, if you're
+			overriding more than 250 functions, maybe speed isn't your main
+			concern...
+	@todo	Add detection of: b, bl, bla, bc, bcl, bcla, bcctrl, bclrl
+			first-instructions. Initially, we should refuse to override
+			functions beginning with these instructions. Eventually, we should
+			dynamically rewrite them to make them position-independent.
+	@todo	Write mach_unoverride(), which would remove an override placed on a
+			function. Must be multiple-override aware, which means an almost
+			complete rewrite under the covers, because the target address can't
+			be spread across two load instructions like it is now since it will
+			need to be atomically updatable.
+	@todo	Add non-rentry variants of overrides to test_mach_override.
+
+	***************************************************************************/
+
+#ifndef		_mach_override_
+#define		_mach_override_
+
+#include <sys/types.h>
+#include <mach/error.h>
+
+#ifdef	__cplusplus
+	extern	"C"	{
+#endif
+
+/**
+	Returned if the function to be overrided begins with a 'mfctr' instruction.
+*/
+#define	err_cannot_override	(err_local|1)
+
+/************************************************************************************//**
+	Dynamically overrides the function implementation referenced by
+	originalFunctionAddress with the implentation pointed to by overrideFunctionAddress.
+	Optionally returns a pointer to a "reentry island" which, if jumped to, will resume
+	the original implementation.
+	
+	@param	originalFunctionAddress			->	Required address of the function to
+												override (with overrideFunctionAddress).
+	@param	overrideFunctionAddress			->	Required address to the overriding
+												function.
+	@param	originalFunctionReentryIsland	<-	Optional pointer to pointer to the
+												reentry island. Can be nullptr.
+	@result									<-	err_cannot_override if the original
+												function's implementation begins with
+												the 'mfctr' instruction.
+
+	************************************************************************************/
+
+    mach_error_t
+mach_override_ptr(
+	void *originalFunctionAddress,
+    const void *overrideFunctionAddress,
+    void **originalFunctionReentryIsland );
+
+/************************************************************************************//**
+	
+
+	************************************************************************************/
+ 
+#ifdef	__cplusplus
+
+#define MACH_OVERRIDE( ORIGINAL_FUNCTION_RETURN_TYPE, ORIGINAL_FUNCTION_NAME, ORIGINAL_FUNCTION_ARGS, ERR )			\
+	{																												\
+		static ORIGINAL_FUNCTION_RETURN_TYPE (*ORIGINAL_FUNCTION_NAME##_reenter)ORIGINAL_FUNCTION_ARGS;				\
+		static bool ORIGINAL_FUNCTION_NAME##_overriden = false;														\
+		class mach_override_class__##ORIGINAL_FUNCTION_NAME {														\
+		public:																										\
+			static kern_return_t override(void *originalFunctionPtr) {												\
+				kern_return_t result = err_none;																	\
+				if (!ORIGINAL_FUNCTION_NAME##_overriden) {															\
+					ORIGINAL_FUNCTION_NAME##_overriden = true;														\
+					result = mach_override_ptr( (void*)originalFunctionPtr,											\
+												(void*)mach_override_class__##ORIGINAL_FUNCTION_NAME::replacement,	\
+												(void**)&ORIGINAL_FUNCTION_NAME##_reenter );						\
+				}																									\
+				return result;																						\
+			}																										\
+			static ORIGINAL_FUNCTION_RETURN_TYPE replacement ORIGINAL_FUNCTION_ARGS {
+
+#define END_MACH_OVERRIDE( ORIGINAL_FUNCTION_NAME )																	\
+			}																										\
+		};																											\
+																													\
+		err = mach_override_class__##ORIGINAL_FUNCTION_NAME::override((void*)ORIGINAL_FUNCTION_NAME);				\
+	}
+ 
+#endif
+
+#ifdef	__cplusplus
+	}
+#endif
+#endif	//	_mach_override_
diff --git a/xpcom/build/moz.build b/xpcom/build/moz.build
new file mode 100644
index 000000000..68bd001a2
--- /dev/null
+++ b/xpcom/build/moz.build
@@ -0,0 +1,102 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+EXPORTS += [
+    'nsXPCOM.h',
+    'nsXPCOMCID.h',
+    'nsXPCOMCIDInternal.h',
+    'nsXREAppData.h',
+    'nsXULAppAPI.h',
+    'XREChildData.h',
+    'xrecore.h',
+    'XREShellData.h',
+]
+
+EXPORTS.mozilla += [
+    'FileLocation.h',
+    'IOInterposer.h',
+    'LateWriteChecks.h',
+    'Omnijar.h',
+    'PoisonIOInterposer.h',
+    'ServiceList.h',
+    'Services.h',
+    'XPCOM.h',
+]
+
+if CONFIG['OS_ARCH'] == 'WINNT':
+    EXPORTS += ['nsWindowsDllInterceptor.h']
+    EXPORTS.mozilla += ['perfprobe.h']
+    SOURCES += [
+        'perfprobe.cpp',
+        'PoisonIOInterposerBase.cpp',
+        'PoisonIOInterposerWin.cpp',
+    ]
+elif CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa':
+    UNIFIED_SOURCES += [
+        'PoisonIOInterposerBase.cpp',
+        'PoisonIOInterposerMac.cpp',
+    ]
+    SOURCES += ['mach_override.c']
+    SOURCES['mach_override.c'].flags += ['-Wno-unused-function']
+else:
+    SOURCES += ['PoisonIOInterposerStub.cpp']
+
+include('../glue/objs.mozbuild')
+
+UNIFIED_SOURCES += xpcom_gluens_src_cppsrcs
+UNIFIED_SOURCES += xpcom_glue_src_cppsrcs
+
+UNIFIED_SOURCES += [
+    'FrozenFunctions.cpp',
+    'IOInterposer.cpp',
+    'LateWriteChecks.cpp',
+    'MainThreadIOLogger.cpp',
+    'nsXPCOMStrings.cpp',
+    'Services.cpp',
+    'XPCOMInit.cpp',
+]
+
+if CONFIG['OS_ARCH'] != 'WINNT':
+    SOURCES += [
+        'NSPRInterposer.cpp',
+    ]
+
+# FileLocation.cpp and Omnijar.cpp cannot be built in unified mode because they
+# use plarena.h.
+SOURCES += [
+    'FileLocation.cpp',
+    'Omnijar.cpp',
+]
+
+include('/ipc/chromium/chromium-config.mozbuild')
+
+FINAL_LIBRARY = 'xul'
+
+DEFINES['_IMPL_NS_STRINGAPI'] = True
+DEFINES['OMNIJAR_NAME'] = CONFIG['OMNIJAR_NAME']
+if CONFIG['MOZ_ICU_DATA_ARCHIVE']:
+    DEFINES['MOZ_ICU_DATA_ARCHIVE'] = True
+
+LOCAL_INCLUDES += [
+    '!..',
+    '../base',
+    '../components',
+    '../ds',
+    '../glue',
+    '../io',
+    '../reflect/xptinfo',
+    '../threads',
+    '/chrome',
+    '/docshell/base',
+]
+
+if CONFIG['MOZ_VPX']:
+    LOCAL_INCLUDES += [
+        '/media/libvpx',
+    ]
+
+if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa':
+    CXXFLAGS += CONFIG['TK_CFLAGS']
diff --git a/xpcom/build/nsWindowsDllInterceptor.h b/xpcom/build/nsWindowsDllInterceptor.h
new file mode 100644
index 000000000..f7b7c93fb
--- /dev/null
+++ b/xpcom/build/nsWindowsDllInterceptor.h
@@ -0,0 +1,1127 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef NS_WINDOWS_DLL_INTERCEPTOR_H_
+#define NS_WINDOWS_DLL_INTERCEPTOR_H_
+
+#include "mozilla/Assertions.h"
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/UniquePtr.h"
+#include "nsWindowsHelpers.h"
+
+#include <wchar.h>
+#include <windows.h>
+#include <winternl.h>
+
+/*
+ * Simple function interception.
+ *
+ * We have two separate mechanisms for intercepting a function: We can use the
+ * built-in nop space, if it exists, or we can create a detour.
+ *
+ * Using the built-in nop space works as follows: On x86-32, DLL functions
+ * begin with a two-byte nop (mov edi, edi) and are preceeded by five bytes of
+ * NOP instructions.
+ *
+ * When we detect a function with this prelude, we do the following:
+ *
+ * 1. Write a long jump to our interceptor function into the five bytes of NOPs
+ *    before the function.
+ *
+ * 2. Write a short jump -5 into the two-byte nop at the beginning of the function.
+ *
+ * This mechanism is nice because it's thread-safe.  It's even safe to do if
+ * another thread is currently running the function we're modifying!
+ *
+ * When the WindowsDllNopSpacePatcher is destroyed, we overwrite the short jump
+ * but not the long jump, so re-intercepting the same function won't work,
+ * because its prelude won't match.
+ *
+ *
+ * Unfortunately nop space patching doesn't work on functions which don't have
+ * this magic prelude (and in particular, x86-64 never has the prelude).  So
+ * when we can't use the built-in nop space, we fall back to using a detour,
+ * which works as follows:
+ *
+ * 1. Save first N bytes of OrigFunction to trampoline, where N is a
+ *    number of bytes >= 5 that are instruction aligned.
+ *
+ * 2. Replace first 5 bytes of OrigFunction with a jump to the Hook
+ *    function.
+ *
+ * 3. After N bytes of the trampoline, add a jump to OrigFunction+N to
+ *    continue original program flow.
+ *
+ * 4. Hook function needs to call the trampoline during its execution,
+ *    to invoke the original function (so address of trampoline is
+ *    returned).
+ *
+ * When the WindowsDllDetourPatcher object is destructed, OrigFunction is
+ * patched again to jump directly to the trampoline instead of going through
+ * the hook function. As such, re-intercepting the same function won't work, as
+ * jump instructions are not supported.
+ *
+ * Note that this is not thread-safe.  Sad day.
+ *
+ */
+
+#include <stdint.h>
+
+namespace mozilla {
+namespace internal {
+
+class AutoVirtualProtect
+{
+public:
+  AutoVirtualProtect(void* aFunc, size_t aSize, DWORD aProtect)
+    : mFunc(aFunc), mSize(aSize), mNewProtect(aProtect), mOldProtect(0),
+      mSuccess(false)
+  {}
+
+  ~AutoVirtualProtect()
+  {
+    if (mSuccess) {
+      VirtualProtectEx(GetCurrentProcess(), mFunc, mSize, mOldProtect,
+                       &mOldProtect);
+    }
+  }
+
+  bool Protect()
+  {
+    mSuccess = !!VirtualProtectEx(GetCurrentProcess(), mFunc, mSize,
+                                  mNewProtect, &mOldProtect);
+    if (!mSuccess) {
+      // printf("VirtualProtectEx failed! %d\n", GetLastError());
+    }
+    return mSuccess;
+  }
+
+private:
+  void* const mFunc;
+  size_t const mSize;
+  DWORD const mNewProtect;
+  DWORD mOldProtect;
+  bool mSuccess;
+};
+
+class WindowsDllNopSpacePatcher
+{
+  typedef uint8_t* byteptr_t;
+  HMODULE mModule;
+
+  // Dumb array for remembering the addresses of functions we've patched.
+  // (This should be nsTArray, but non-XPCOM code uses this class.)
+  static const size_t maxPatchedFns = 128;
+  byteptr_t mPatchedFns[maxPatchedFns];
+  int mPatchedFnsLen;
+
+public:
+  WindowsDllNopSpacePatcher()
+    : mModule(0)
+    , mPatchedFnsLen(0)
+  {}
+
+#if defined(_M_IX86)
+  ~WindowsDllNopSpacePatcher()
+  {
+    // Restore the mov edi, edi to the beginning of each function we patched.
+
+    for (int i = 0; i < mPatchedFnsLen; i++) {
+      byteptr_t fn = mPatchedFns[i];
+
+      // Ensure we can write to the code.
+      AutoVirtualProtect protect(fn, 2, PAGE_EXECUTE_READWRITE);
+      if (!protect.Protect()) {
+        continue;
+      }
+
+      // mov edi, edi
+      *((uint16_t*)fn) = 0xff8b;
+
+      // I don't think this is actually necessary, but it can't hurt.
+      FlushInstructionCache(GetCurrentProcess(),
+                            /* ignored */ nullptr,
+                            /* ignored */ 0);
+    }
+  }
+
+  void Init(const char* aModuleName)
+  {
+    if (!IsCompatible()) {
+#if defined(MOZILLA_INTERNAL_API)
+      NS_WARNING("NOP space patching is unavailable for compatibility reasons");
+#endif
+      return;
+    }
+
+    mModule = LoadLibraryExA(aModuleName, nullptr, 0);
+    if (!mModule) {
+      //printf("LoadLibraryEx for '%s' failed\n", aModuleName);
+      return;
+    }
+  }
+
+  /**
+   * NVIDIA Optimus drivers utilize Microsoft Detours 2.x to patch functions
+   * in our address space. There is a bug in Detours 2.x that causes it to
+   * patch at the wrong address when attempting to detour code that is already
+   * NOP space patched. This function is an effort to detect the presence of
+   * this NVIDIA code in our address space and disable NOP space patching if it
+   * is. We also check AppInit_DLLs since this is the mechanism that the Optimus
+   * drivers use to inject into our process.
+   */
+  static bool IsCompatible()
+  {
+    // These DLLs are known to have bad interactions with this style of patching
+    const wchar_t* kIncompatibleDLLs[] = {
+      L"detoured.dll",
+      L"_etoured.dll",
+      L"nvd3d9wrap.dll",
+      L"nvdxgiwrap.dll"
+    };
+    // See if the infringing DLLs are already loaded
+    for (unsigned int i = 0; i < mozilla::ArrayLength(kIncompatibleDLLs); ++i) {
+      if (GetModuleHandleW(kIncompatibleDLLs[i])) {
+        return false;
+      }
+    }
+    if (GetModuleHandleW(L"user32.dll")) {
+      // user32 is loaded but the infringing DLLs are not, assume we're safe to
+      // proceed.
+      return true;
+    }
+    // If user32 has not loaded yet, check AppInit_DLLs to ensure that Optimus
+    // won't be loaded once user32 is initialized.
+    HKEY hkey = NULL;
+    if (!RegOpenKeyExW(HKEY_LOCAL_MACHINE,
+          L"SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Windows",
+          0, KEY_QUERY_VALUE, &hkey)) {
+      nsAutoRegKey key(hkey);
+      DWORD numBytes = 0;
+      const wchar_t kAppInitDLLs[] = L"AppInit_DLLs";
+      // Query for required buffer size
+      LONG status = RegQueryValueExW(hkey, kAppInitDLLs, nullptr,
+                                     nullptr, nullptr, &numBytes);
+      mozilla::UniquePtr<wchar_t[]> data;
+      if (!status) {
+        // Allocate the buffer and query for the actual data
+        data = mozilla::MakeUnique<wchar_t[]>(numBytes / sizeof(wchar_t));
+        status = RegQueryValueExW(hkey, kAppInitDLLs, nullptr,
+                                  nullptr, (LPBYTE)data.get(), &numBytes);
+      }
+      if (!status) {
+        // For each token, split up the filename components and then check the
+        // name of the file.
+        const wchar_t kDelimiters[] = L", ";
+        wchar_t* tokenContext = nullptr;
+        wchar_t* token = wcstok_s(data.get(), kDelimiters, &tokenContext);
+        while (token) {
+          wchar_t fname[_MAX_FNAME] = {0};
+          if (!_wsplitpath_s(token, nullptr, 0, nullptr, 0,
+                             fname, mozilla::ArrayLength(fname),
+                             nullptr, 0)) {
+            // nvinit.dll is responsible for bootstrapping the DLL injection, so
+            // that is the library that we check for here
+            const wchar_t kNvInitName[] = L"nvinit";
+            if (!_wcsnicmp(fname, kNvInitName,
+                           mozilla::ArrayLength(kNvInitName))) {
+              return false;
+            }
+          }
+          token = wcstok_s(nullptr, kDelimiters, &tokenContext);
+        }
+      }
+    }
+    return true;
+  }
+
+  bool AddHook(const char* aName, intptr_t aHookDest, void** aOrigFunc)
+  {
+    if (!mModule) {
+      return false;
+    }
+
+    if (!IsCompatible()) {
+#if defined(MOZILLA_INTERNAL_API)
+      NS_WARNING("NOP space patching is unavailable for compatibility reasons");
+#endif
+      return false;
+    }
+
+    if (mPatchedFnsLen == maxPatchedFns) {
+      // printf ("No space for hook in mPatchedFns.\n");
+      return false;
+    }
+
+    byteptr_t fn = reinterpret_cast<byteptr_t>(GetProcAddress(mModule, aName));
+    if (!fn) {
+      //printf ("GetProcAddress failed\n");
+      return false;
+    }
+
+    fn = ResolveRedirectedAddress(fn);
+
+    // Ensure we can read and write starting at fn - 5 (for the long jmp we're
+    // going to write) and ending at fn + 2 (for the short jmp up to the long
+    // jmp). These bytes may span two pages with different protection.
+    AutoVirtualProtect protectBefore(fn - 5, 5, PAGE_EXECUTE_READWRITE);
+    AutoVirtualProtect protectAfter(fn, 2, PAGE_EXECUTE_READWRITE);
+    if (!protectBefore.Protect() || !protectAfter.Protect()) {
+      return false;
+    }
+
+    bool rv = WriteHook(fn, aHookDest, aOrigFunc);
+
+    if (rv) {
+      mPatchedFns[mPatchedFnsLen] = fn;
+      mPatchedFnsLen++;
+    }
+
+    return rv;
+  }
+
+  bool WriteHook(byteptr_t aFn, intptr_t aHookDest, void** aOrigFunc)
+  {
+    // Check that the 5 bytes before aFn are NOP's or INT 3's,
+    // and that the 2 bytes after aFn are mov(edi, edi).
+    //
+    // It's safe to read aFn[-5] because we set it to PAGE_EXECUTE_READWRITE
+    // before calling WriteHook.
+
+    for (int i = -5; i <= -1; i++) {
+      if (aFn[i] != 0x90 && aFn[i] != 0xcc) { // nop or int 3
+        return false;
+      }
+    }
+
+    // mov edi, edi.  Yes, there are two ways to encode the same thing:
+    //
+    //   0x89ff == mov r/m, r
+    //   0x8bff == mov r, r/m
+    //
+    // where "r" is register and "r/m" is register or memory.  Windows seems to
+    // use 8bff; I include 89ff out of paranoia.
+    if ((aFn[0] != 0x8b && aFn[0] != 0x89) || aFn[1] != 0xff) {
+      return false;
+    }
+
+    // Write a long jump into the space above the function.
+    aFn[-5] = 0xe9; // jmp
+    *((intptr_t*)(aFn - 4)) = aHookDest - (uintptr_t)(aFn); // target displacement
+
+    // Set aOrigFunc here, because after this point, aHookDest might be called,
+    // and aHookDest might use the aOrigFunc pointer.
+    *aOrigFunc = aFn + 2;
+
+    // Short jump up into our long jump.
+    *((uint16_t*)(aFn)) = 0xf9eb; // jmp $-5
+
+    // I think this routine is safe without this, but it can't hurt.
+    FlushInstructionCache(GetCurrentProcess(),
+                          /* ignored */ nullptr,
+                          /* ignored */ 0);
+
+    return true;
+  }
+
+private:
+  static byteptr_t ResolveRedirectedAddress(const byteptr_t aOriginalFunction)
+  {
+    // If function entry is jmp [disp32] such as used by kernel32,
+    // we resolve redirected address from import table.
+    if (aOriginalFunction[0] == 0xff && aOriginalFunction[1] == 0x25) {
+      return (byteptr_t)(**((uint32_t**) (aOriginalFunction + 2)));
+    }
+
+    return aOriginalFunction;
+  }
+#else
+  void Init(const char* aModuleName)
+  {
+    // Not implemented except on x86-32.
+  }
+
+  bool AddHook(const char* aName, intptr_t aHookDest, void** aOrigFunc)
+  {
+    // Not implemented except on x86-32.
+    return false;
+  }
+#endif
+};
+
+class WindowsDllDetourPatcher
+{
+  typedef unsigned char* byteptr_t;
+public:
+  WindowsDllDetourPatcher()
+    : mModule(0), mHookPage(0), mMaxHooks(0), mCurHooks(0)
+  {
+  }
+
+  ~WindowsDllDetourPatcher()
+  {
+    int i;
+    byteptr_t p;
+    for (i = 0, p = mHookPage; i < mCurHooks; i++, p += kHookSize) {
+#if defined(_M_IX86)
+      size_t nBytes = 1 + sizeof(intptr_t);
+#elif defined(_M_X64)
+      size_t nBytes = 2 + sizeof(intptr_t);
+#else
+#error "Unknown processor type"
+#endif
+      byteptr_t origBytes = (byteptr_t)DecodePointer(*((byteptr_t*)p));
+
+      // ensure we can modify the original code
+      AutoVirtualProtect protect(origBytes, nBytes, PAGE_EXECUTE_READWRITE);
+      if (!protect.Protect()) {
+        continue;
+      }
+
+      // Remove the hook by making the original function jump directly
+      // in the trampoline.
+      intptr_t dest = (intptr_t)(p + sizeof(void*));
+#if defined(_M_IX86)
+      // Ensure the JMP from CreateTrampoline is where we expect it to be.
+      if (origBytes[0] != 0xE9)
+        continue;
+      *((intptr_t*)(origBytes + 1)) =
+        dest - (intptr_t)(origBytes + 5); // target displacement
+#elif defined(_M_X64)
+      // Ensure the MOV R11 from CreateTrampoline is where we expect it to be.
+      if (origBytes[0] != 0x49 || origBytes[1] != 0xBB)
+        continue;
+      *((intptr_t*)(origBytes + 2)) = dest;
+#else
+#error "Unknown processor type"
+#endif
+    }
+  }
+
+  void Init(const char* aModuleName, int aNumHooks = 0)
+  {
+    if (mModule) {
+      return;
+    }
+
+    mModule = LoadLibraryExA(aModuleName, nullptr, 0);
+    if (!mModule) {
+      //printf("LoadLibraryEx for '%s' failed\n", aModuleName);
+      return;
+    }
+
+    int hooksPerPage = 4096 / kHookSize;
+    if (aNumHooks == 0) {
+      aNumHooks = hooksPerPage;
+    }
+
+    mMaxHooks = aNumHooks + (hooksPerPage % aNumHooks);
+
+    mHookPage = (byteptr_t)VirtualAllocEx(GetCurrentProcess(), nullptr,
+                                          mMaxHooks * kHookSize,
+                                          MEM_COMMIT | MEM_RESERVE,
+                                          PAGE_EXECUTE_READ);
+    if (!mHookPage) {
+      mModule = 0;
+      return;
+    }
+  }
+
+  bool Initialized() { return !!mModule; }
+
+  bool AddHook(const char* aName, intptr_t aHookDest, void** aOrigFunc)
+  {
+    if (!mModule) {
+      return false;
+    }
+
+    void* pAddr = (void*)GetProcAddress(mModule, aName);
+    if (!pAddr) {
+      //printf ("GetProcAddress failed\n");
+      return false;
+    }
+
+    pAddr = ResolveRedirectedAddress((byteptr_t)pAddr);
+
+    CreateTrampoline(pAddr, aHookDest, aOrigFunc);
+    if (!*aOrigFunc) {
+      //printf ("CreateTrampoline failed\n");
+      return false;
+    }
+
+    return true;
+  }
+
+protected:
+  const static int kPageSize = 4096;
+  const static int kHookSize = 128;
+
+  HMODULE mModule;
+  byteptr_t mHookPage;
+  int mMaxHooks;
+  int mCurHooks;
+
+  // rex bits
+  static const BYTE kMaskHighNibble = 0xF0;
+  static const BYTE kRexOpcode = 0x40;
+  static const BYTE kMaskRexW = 0x08;
+  static const BYTE kMaskRexR = 0x04;
+  static const BYTE kMaskRexX = 0x02;
+  static const BYTE kMaskRexB = 0x01;
+
+  // mod r/m bits
+  static const BYTE kRegFieldShift = 3;
+  static const BYTE kMaskMod = 0xC0;
+  static const BYTE kMaskReg = 0x38;
+  static const BYTE kMaskRm = 0x07;
+  static const BYTE kRmNeedSib = 0x04;
+  static const BYTE kModReg = 0xC0;
+  static const BYTE kModDisp32 = 0x80;
+  static const BYTE kModDisp8 = 0x40;
+  static const BYTE kModNoRegDisp = 0x00;
+  static const BYTE kRmNoRegDispDisp32 = 0x05;
+
+  // sib bits
+  static const BYTE kMaskSibScale = 0xC0;
+  static const BYTE kMaskSibIndex = 0x38;
+  static const BYTE kMaskSibBase = 0x07;
+  static const BYTE kSibBaseEbp = 0x05;
+
+  int CountModRmSib(const BYTE *aModRm, BYTE* aSubOpcode = nullptr)
+  {
+    if (!aModRm) {
+      return -1;
+    }
+    int numBytes = 1; // Start with 1 for mod r/m byte itself
+    switch (*aModRm & kMaskMod) {
+      case kModReg:
+        return numBytes;
+      case kModDisp8:
+        numBytes += 1;
+        break;
+      case kModDisp32:
+        numBytes += 4;
+        break;
+      case kModNoRegDisp:
+        if ((*aModRm & kMaskRm) == kRmNoRegDispDisp32) {
+#if defined(_M_X64)
+          // RIP-relative on AMD64, currently unsupported
+          return -1;
+#else
+          // On IA-32, all ModR/M instruction modes address memory relative to 0
+          numBytes += 4;
+#endif
+        } else if (((*aModRm & kMaskRm) == kRmNeedSib &&
+             (*(aModRm + 1) & kMaskSibBase) == kSibBaseEbp)) {
+          numBytes += 4;
+        }
+        break;
+      default:
+        // This should not be reachable
+        MOZ_ASSERT_UNREACHABLE("Impossible value for modr/m byte mod bits");
+        return -1;
+    }
+    if ((*aModRm & kMaskRm) == kRmNeedSib) {
+      // SIB byte
+      numBytes += 1;
+    }
+    if (aSubOpcode) {
+      *aSubOpcode = (*aModRm & kMaskReg) >> kRegFieldShift;
+    }
+    return numBytes;
+  }
+
+#if defined(_M_X64)
+  // To patch for JMP and JE
+
+  enum JumpType {
+   Je,
+   Jmp
+  };
+
+  struct JumpPatch {
+    JumpPatch()
+      : mHookOffset(0), mJumpAddress(0), mType(JumpType::Jmp)
+    {
+    }
+
+    JumpPatch(size_t aOffset, intptr_t aAddress, JumpType aType = JumpType::Jmp)
+      : mHookOffset(aOffset), mJumpAddress(aAddress), mType(aType)
+    {
+    }
+
+    void AddJumpPatch(size_t aHookOffset, intptr_t aAbsJumpAddress,
+                     JumpType aType = JumpType::Jmp)
+    {
+      mHookOffset = aHookOffset;
+      mJumpAddress = aAbsJumpAddress;
+      mType = aType;
+    }
+
+    size_t GenerateJump(uint8_t* aCode)
+    {
+      size_t offset = mHookOffset;
+      if (mType == JumpType::Je) {
+        // JNE RIP+14
+        aCode[offset]     = 0x75;
+        aCode[offset + 1] = 14;
+        offset += 2;
+      }
+
+      // JMP [RIP+0]
+      aCode[offset] = 0xff;
+      aCode[offset + 1] = 0x25;
+      *reinterpret_cast<int32_t*>(aCode + offset + 2) = 0;
+
+      // Jump table
+      *reinterpret_cast<int64_t*>(aCode + offset + 2 + 4) = mJumpAddress;
+
+      return offset + 2 + 4 + 8;
+    }
+
+    bool HasJumpPatch() const
+    {
+      return !!mJumpAddress;
+    }
+
+    size_t mHookOffset;
+    intptr_t mJumpAddress;
+    JumpType mType;
+  };
+
+#endif
+
+  enum ePrefixGroupBits
+  {
+    eNoPrefixes = 0,
+    ePrefixGroup1 = (1 << 0),
+    ePrefixGroup2 = (1 << 1),
+    ePrefixGroup3 = (1 << 2),
+    ePrefixGroup4 = (1 << 3)
+  };
+
+  int CountPrefixBytes(byteptr_t aBytes, const int aBytesIndex,
+                       unsigned char* aOutGroupBits)
+  {
+    unsigned char& groupBits = *aOutGroupBits;
+    groupBits = eNoPrefixes;
+    int index = aBytesIndex;
+    while (true) {
+      switch (aBytes[index]) {
+        // Group 1
+        case 0xF0: // LOCK
+        case 0xF2: // REPNZ
+        case 0xF3: // REP / REPZ
+          if (groupBits & ePrefixGroup1) {
+            return -1;
+          }
+          groupBits |= ePrefixGroup1;
+          ++index;
+          break;
+
+        // Group 2
+        case 0x2E: // CS override / branch not taken
+        case 0x36: // SS override
+        case 0x3E: // DS override / branch taken
+        case 0x64: // FS override
+        case 0x65: // GS override
+          if (groupBits & ePrefixGroup2) {
+            return -1;
+          }
+          groupBits |= ePrefixGroup2;
+          ++index;
+          break;
+
+        // Group 3
+        case 0x66: // operand size override
+          if (groupBits & ePrefixGroup3) {
+            return -1;
+          }
+          groupBits |= ePrefixGroup3;
+          ++index;
+          break;
+
+        // Group 4
+        case 0x67: // Address size override
+          if (groupBits & ePrefixGroup4) {
+            return -1;
+          }
+          groupBits |= ePrefixGroup4;
+          ++index;
+          break;
+
+        default:
+          return index - aBytesIndex;
+      }
+    }
+  }
+
+  void CreateTrampoline(void* aOrigFunction, intptr_t aDest, void** aOutTramp)
+  {
+    *aOutTramp = nullptr;
+
+    AutoVirtualProtect protectHookPage(mHookPage, mMaxHooks * kHookSize,
+                                       PAGE_EXECUTE_READWRITE);
+    if (!protectHookPage.Protect()) {
+      return;
+    }
+
+    byteptr_t tramp = FindTrampolineSpace();
+    if (!tramp) {
+      return;
+    }
+
+    byteptr_t origBytes = (byteptr_t)aOrigFunction;
+
+    int nBytes = 0;
+
+#if defined(_M_IX86)
+    int pJmp32 = -1;
+    while (nBytes < 5) {
+      // Understand some simple instructions that might be found in a
+      // prologue; we might need to extend this as necessary.
+      //
+      // Note!  If we ever need to understand jump instructions, we'll
+      // need to rewrite the displacement argument.
+      unsigned char prefixGroups;
+      int numPrefixBytes = CountPrefixBytes(origBytes, nBytes, &prefixGroups);
+      if (numPrefixBytes < 0 || (prefixGroups & (ePrefixGroup3 | ePrefixGroup4))) {
+        // Either the prefix sequence was bad, or there are prefixes that
+        // we don't currently support (groups 3 and 4)
+        return;
+      }
+      nBytes += numPrefixBytes;
+      if (origBytes[nBytes] >= 0x88 && origBytes[nBytes] <= 0x8B) {
+        // various MOVs
+        ++nBytes;
+        int len = CountModRmSib(origBytes + nBytes);
+        if (len < 0) {
+          return;
+        }
+        nBytes += len;
+      } else if (origBytes[nBytes] == 0xA1) {
+        // MOV eax, [seg:offset]
+        nBytes += 5;
+      } else if (origBytes[nBytes] == 0xB8) {
+        // MOV 0xB8: http://ref.x86asm.net/coder32.html#xB8
+        nBytes += 5;
+      } else if (origBytes[nBytes] == 0x83) {
+        // ADD|ODR|ADC|SBB|AND|SUB|XOR|CMP r/m, imm8
+        unsigned char b = origBytes[nBytes + 1];
+        if ((b & 0xc0) == 0xc0) {
+          // ADD|ODR|ADC|SBB|AND|SUB|XOR|CMP r, imm8
+          nBytes += 3;
+        } else {
+          // bail
+          return;
+        }
+      } else if (origBytes[nBytes] == 0x68) {
+        // PUSH with 4-byte operand
+        nBytes += 5;
+      } else if ((origBytes[nBytes] & 0xf0) == 0x50) {
+        // 1-byte PUSH/POP
+        nBytes++;
+      } else if (origBytes[nBytes] == 0x6A) {
+        // PUSH imm8
+        nBytes += 2;
+      } else if (origBytes[nBytes] == 0xe9) {
+        pJmp32 = nBytes;
+        // jmp 32bit offset
+        nBytes += 5;
+      } else if (origBytes[nBytes] == 0xff && origBytes[nBytes + 1] == 0x25) {
+        // jmp [disp32]
+        nBytes += 6;
+      } else {
+        //printf ("Unknown x86 instruction byte 0x%02x, aborting trampoline\n", origBytes[nBytes]);
+        return;
+      }
+    }
+#elif defined(_M_X64)
+    JumpPatch jump;
+
+    while (nBytes < 13) {
+
+      // if found JMP 32bit offset, next bytes must be NOP or INT3
+      if (jump.HasJumpPatch()) {
+        if (origBytes[nBytes] == 0x90 || origBytes[nBytes] == 0xcc) {
+          nBytes++;
+          continue;
+        }
+        return;
+      }
+      if (origBytes[nBytes] == 0x0f) {
+        nBytes++;
+        if (origBytes[nBytes] == 0x1f) {
+          // nop (multibyte)
+          nBytes++;
+          if ((origBytes[nBytes] & 0xc0) == 0x40 &&
+              (origBytes[nBytes] & 0x7) == 0x04) {
+            nBytes += 3;
+          } else {
+            return;
+          }
+        } else if (origBytes[nBytes] == 0x05) {
+          // syscall
+          nBytes++;
+        } else if (origBytes[nBytes] == 0x84) {
+          // je rel32
+          jump.AddJumpPatch(nBytes - 1,
+                            (intptr_t)
+                              origBytes + nBytes + 5 +
+                            *(reinterpret_cast<int32_t*>(origBytes +
+                                                         nBytes + 1)),
+                            JumpType::Je);
+          nBytes += 5;
+        } else {
+          return;
+        }
+      } else if (origBytes[nBytes] == 0x40 ||
+                 origBytes[nBytes] == 0x41) {
+        // Plain REX or REX.B
+        nBytes++;
+
+        if ((origBytes[nBytes] & 0xf0) == 0x50) {
+          // push/pop with Rx register
+          nBytes++;
+        } else if (origBytes[nBytes] >= 0xb8 && origBytes[nBytes] <= 0xbf) {
+          // mov r32, imm32
+          nBytes += 5;
+        } else {
+          return;
+        }
+      } else if (origBytes[nBytes] == 0x45) {
+        // REX.R & REX.B
+        nBytes++;
+
+        if (origBytes[nBytes] == 0x33) {
+          // xor r32, r32
+          nBytes += 2;
+        } else {
+          return;
+        }
+      } else if ((origBytes[nBytes] & 0xfb) == 0x48) {
+        // REX.W | REX.WR
+        nBytes++;
+
+        if (origBytes[nBytes] == 0x81 &&
+            (origBytes[nBytes + 1] & 0xf8) == 0xe8) {
+          // sub r, dword
+          nBytes += 6;
+        } else if (origBytes[nBytes] == 0x83 &&
+                   (origBytes[nBytes + 1] & 0xf8) == 0xe8) {
+          // sub r, byte
+          nBytes += 3;
+        } else if (origBytes[nBytes] == 0x83 &&
+                   (origBytes[nBytes + 1] & 0xf8) == 0x60) {
+          // and [r+d], imm8
+          nBytes += 5;
+        } else if (origBytes[nBytes] == 0x85) {
+          // 85 /r => TEST r/m32, r32
+          if ((origBytes[nBytes + 1] & 0xc0) == 0xc0) {
+            nBytes += 2;
+          } else {
+            return;
+          }
+        } else if ((origBytes[nBytes] & 0xfd) == 0x89) {
+          ++nBytes;
+          // MOV r/m64, r64 | MOV r64, r/m64
+          int len = CountModRmSib(origBytes + nBytes);
+          if (len < 0) {
+            return;
+          }
+          nBytes += len;
+        } else if (origBytes[nBytes] == 0xc7) {
+          // MOV r/m64, imm32
+          if (origBytes[nBytes + 1] == 0x44) {
+            // MOV [r64+disp8], imm32
+            // ModR/W + SIB + disp8 + imm32
+            nBytes += 8;
+          } else {
+            return;
+          }
+        } else if (origBytes[nBytes] == 0xff) {
+          // JMP /4
+          if ((origBytes[nBytes + 1] & 0xc0) == 0x0 &&
+              (origBytes[nBytes + 1] & 0x07) == 0x5) {
+            // [rip+disp32]
+            // convert JMP 32bit offset to JMP 64bit direct
+            jump.AddJumpPatch(nBytes - 1,
+                              *reinterpret_cast<intptr_t*>(
+                                origBytes + nBytes + 6 +
+                              *reinterpret_cast<int32_t*>(origBytes + nBytes +
+                                                          2)));
+            nBytes += 6;
+          } else {
+            // not support yet!
+            return;
+          }
+        } else {
+          // not support yet!
+          return;
+        }
+      } else if (origBytes[nBytes] == 0x66) {
+        // operand override prefix
+        nBytes += 1;
+        // This is the same as the x86 version
+        if (origBytes[nBytes] >= 0x88 && origBytes[nBytes] <= 0x8B) {
+          // various MOVs
+          unsigned char b = origBytes[nBytes + 1];
+          if (((b & 0xc0) == 0xc0) ||
+              (((b & 0xc0) == 0x00) &&
+               ((b & 0x07) != 0x04) && ((b & 0x07) != 0x05))) {
+            // REG=r, R/M=r or REG=r, R/M=[r]
+            nBytes += 2;
+          } else if ((b & 0xc0) == 0x40) {
+            if ((b & 0x07) == 0x04) {
+              // REG=r, R/M=[SIB + disp8]
+              nBytes += 4;
+            } else {
+              // REG=r, R/M=[r + disp8]
+              nBytes += 3;
+            }
+          } else {
+            // complex MOV, bail
+            return;
+          }
+        }
+      } else if ((origBytes[nBytes] & 0xf0) == 0x50) {
+        // 1-byte push/pop
+        nBytes++;
+      } else if (origBytes[nBytes] == 0x65) {
+        // GS prefix
+        //
+        // The entry of GetKeyState on Windows 10 has the following code.
+        // 65 48 8b 04 25 30 00 00 00    mov   rax,qword ptr gs:[30h]
+        // (GS prefix + REX + MOV (0x8b) ...)
+        if (origBytes[nBytes + 1] == 0x48 &&
+            (origBytes[nBytes + 2] >= 0x88 && origBytes[nBytes + 2] <= 0x8b)) {
+          nBytes += 3;
+          int len = CountModRmSib(origBytes + nBytes);
+          if (len < 0) {
+            // no way to support this yet.
+            return;
+          }
+          nBytes += len;
+        } else {
+          return;
+        }
+      } else if (origBytes[nBytes] == 0x90) {
+        // nop
+        nBytes++;
+      } else if (origBytes[nBytes] == 0xb8) {
+        // MOV 0xB8: http://ref.x86asm.net/coder32.html#xB8
+        nBytes += 5;
+      } else if (origBytes[nBytes] == 0x33) {
+        // xor r32, r/m32
+        nBytes += 2;
+      } else if (origBytes[nBytes] == 0xf6) {
+        // test r/m8, imm8 (used by ntdll on Windows 10 x64)
+        // (no flags are affected by near jmp since there is no task switch,
+        // so it is ok for a jmp to be written immediately after a test)
+        BYTE subOpcode = 0;
+        int nModRmSibBytes = CountModRmSib(&origBytes[nBytes + 1], &subOpcode);
+        if (nModRmSibBytes < 0 || subOpcode != 0) {
+          // Unsupported
+          return;
+        }
+        nBytes += 2 + nModRmSibBytes;
+      } else if (origBytes[nBytes] == 0xc3) {
+        // ret
+        nBytes++;
+      } else if (origBytes[nBytes] == 0xcc) {
+        // int 3
+        nBytes++;
+      } else if (origBytes[nBytes] == 0xe9) {
+        // jmp 32bit offset
+        jump.AddJumpPatch(nBytes,
+                          // convert JMP 32bit offset to JMP 64bit direct
+                          (intptr_t)
+                            origBytes + nBytes + 5 +
+                          *(reinterpret_cast<int32_t*>(origBytes + nBytes + 1)));
+        nBytes += 5;
+      } else if (origBytes[nBytes] == 0xff) {
+        nBytes++;
+        if ((origBytes[nBytes] & 0xf8) == 0xf0) {
+          // push r64
+          nBytes++;
+        } else {
+          return;
+        }
+      } else {
+        return;
+      }
+    }
+#else
+#error "Unknown processor type"
+#endif
+
+    if (nBytes > 100) {
+      //printf ("Too big!");
+      return;
+    }
+
+    // We keep the address of the original function in the first bytes of
+    // the trampoline buffer
+    *((void**)tramp) = EncodePointer(aOrigFunction);
+    tramp += sizeof(void*);
+
+    memcpy(tramp, aOrigFunction, nBytes);
+
+    // OrigFunction+N, the target of the trampoline
+    byteptr_t trampDest = origBytes + nBytes;
+
+#if defined(_M_IX86)
+    if (pJmp32 >= 0) {
+      // Jump directly to the original target of the jump instead of jumping to the
+      // original function.
+      // Adjust jump target displacement to jump location in the trampoline.
+      *((intptr_t*)(tramp + pJmp32 + 1)) += origBytes - tramp;
+    } else {
+      tramp[nBytes] = 0xE9; // jmp
+      *((intptr_t*)(tramp + nBytes + 1)) =
+        (intptr_t)trampDest - (intptr_t)(tramp + nBytes + 5); // target displacement
+    }
+#elif defined(_M_X64)
+    // If JMP/JE opcode found, we don't insert to trampoline jump
+    if (jump.HasJumpPatch()) {
+      size_t offset = jump.GenerateJump(tramp);
+      if (jump.mType != JumpType::Jmp) {
+        JumpPatch patch(offset, reinterpret_cast<intptr_t>(trampDest));
+        patch.GenerateJump(tramp);
+      }
+    } else {
+      JumpPatch patch(nBytes, reinterpret_cast<intptr_t>(trampDest));
+      patch.GenerateJump(tramp);
+    }
+#endif
+
+    // The trampoline is now valid.
+    *aOutTramp = tramp;
+
+    // ensure we can modify the original code
+    AutoVirtualProtect protect(aOrigFunction, nBytes, PAGE_EXECUTE_READWRITE);
+    if (!protect.Protect()) {
+      return;
+    }
+
+#if defined(_M_IX86)
+    // now modify the original bytes
+    origBytes[0] = 0xE9; // jmp
+    *((intptr_t*)(origBytes + 1)) =
+      aDest - (intptr_t)(origBytes + 5); // target displacement
+#elif defined(_M_X64)
+    // mov r11, address
+    origBytes[0] = 0x49;
+    origBytes[1] = 0xbb;
+
+    *((intptr_t*)(origBytes + 2)) = aDest;
+
+    // jmp r11
+    origBytes[10] = 0x41;
+    origBytes[11] = 0xff;
+    origBytes[12] = 0xe3;
+#endif
+  }
+
+  byteptr_t FindTrampolineSpace()
+  {
+    if (mCurHooks >= mMaxHooks) {
+      return 0;
+    }
+
+    byteptr_t p = mHookPage + mCurHooks * kHookSize;
+
+    mCurHooks++;
+
+    return p;
+  }
+
+  static void* ResolveRedirectedAddress(const byteptr_t aOriginalFunction)
+  {
+#if defined(_M_IX86)
+    // If function entry is jmp [disp32] such as used by kernel32,
+    // we resolve redirected address from import table.
+    if (aOriginalFunction[0] == 0xff && aOriginalFunction[1] == 0x25) {
+      return (void*)(**((uint32_t**) (aOriginalFunction + 2)));
+    }
+#elif defined(_M_X64)
+    if (aOriginalFunction[0] == 0xe9) {
+      // require for TestDllInterceptor with --disable-optimize
+      int32_t offset = *((int32_t*)(aOriginalFunction + 1));
+      return aOriginalFunction + 5 + offset;
+    }
+#endif
+
+    return aOriginalFunction;
+  }
+};
+
+} // namespace internal
+
+class WindowsDllInterceptor
+{
+  internal::WindowsDllNopSpacePatcher mNopSpacePatcher;
+  internal::WindowsDllDetourPatcher mDetourPatcher;
+
+  const char* mModuleName;
+  int mNHooks;
+
+public:
+  WindowsDllInterceptor()
+    : mModuleName(nullptr)
+    , mNHooks(0)
+  {}
+
+  void Init(const char* aModuleName, int aNumHooks = 0)
+  {
+    if (mModuleName) {
+      return;
+    }
+
+    mModuleName = aModuleName;
+    mNHooks = aNumHooks;
+    mNopSpacePatcher.Init(aModuleName);
+
+    // Lazily initialize mDetourPatcher, since it allocates memory and we might
+    // not need it.
+  }
+
+  bool AddHook(const char* aName, intptr_t aHookDest, void** aOrigFunc)
+  {
+    // Use a nop space patch if possible, otherwise fall back to a detour.
+    // This should be the preferred method for adding hooks.
+
+    if (!mModuleName) {
+      return false;
+    }
+
+    if (mNopSpacePatcher.AddHook(aName, aHookDest, aOrigFunc)) {
+      return true;
+    }
+
+    return AddDetour(aName, aHookDest, aOrigFunc);
+  }
+
+  bool AddDetour(const char* aName, intptr_t aHookDest, void** aOrigFunc)
+  {
+    // Generally, code should not call this method directly. Use AddHook unless
+    // there is a specific need to avoid nop space patches.
+
+    if (!mModuleName) {
+      return false;
+    }
+
+    if (!mDetourPatcher.Initialized()) {
+      mDetourPatcher.Init(mModuleName, mNHooks);
+    }
+
+    return mDetourPatcher.AddHook(aName, aHookDest, aOrigFunc);
+  }
+};
+
+} // namespace mozilla
+
+#endif /* NS_WINDOWS_DLL_INTERCEPTOR_H_ */
diff --git a/xpcom/build/nsXPCOM.h b/xpcom/build/nsXPCOM.h
new file mode 100644
index 000000000..925ca6901
--- /dev/null
+++ b/xpcom/build/nsXPCOM.h
@@ -0,0 +1,433 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsXPCOM_h__
+#define nsXPCOM_h__
+
+#include "nscore.h"
+#include "nsXPCOMCID.h"
+
+#ifdef __cplusplus
+#define DECL_CLASS(c) class c
+#define DECL_STRUCT(c) struct c
+#else
+#define DECL_CLASS(c) typedef struct c c
+#define DECL_STRUCT(c) typedef struct c c
+#endif
+
+DECL_CLASS(nsAString);
+DECL_CLASS(nsACString);
+
+DECL_CLASS(nsISupports);
+DECL_CLASS(nsIModule);
+DECL_CLASS(nsIComponentManager);
+DECL_CLASS(nsIComponentRegistrar);
+DECL_CLASS(nsIServiceManager);
+DECL_CLASS(nsIFile);
+DECL_CLASS(nsILocalFile);
+DECL_CLASS(nsIDirectoryServiceProvider);
+DECL_CLASS(nsIMemory);
+DECL_CLASS(nsIDebug2);
+
+#ifdef __cplusplus
+namespace mozilla {
+struct Module;
+} // namespace mozilla
+#endif
+
+/**
+ * Initialises XPCOM. You must call one of the NS_InitXPCOM methods
+ * before proceeding to use xpcom. The one exception is that you may
+ * call NS_NewLocalFile to create a nsIFile.
+ *
+ * @note Use <CODE>NS_NewLocalFile</CODE> or <CODE>NS_NewNativeLocalFile</CODE>
+ *       to create the file object you supply as the bin directory path in this
+ *       call. The function may be safely called before the rest of XPCOM or
+ *       embedding has been initialised.
+ *
+ * @param aResult          The service manager.  You may pass null.
+ *
+ * @param aBinDirectory    The directory containing the component
+ *                         registry and runtime libraries;
+ *                         or use <CODE>nullptr</CODE> to use the working
+ *                         directory.
+ *
+ * @param aAppFileLocationProvider The object to be used by Gecko that
+ *                         specifies to Gecko where to find profiles, the
+ *                         component registry preferences and so on; or use
+ *                         <CODE>nullptr</CODE> for the default behaviour.
+ *
+ * @see NS_NewLocalFile
+ * @see nsIFile
+ * @see nsIDirectoryServiceProvider
+ *
+ * @return NS_OK for success;
+ *         NS_ERROR_NOT_INITIALIZED if static globals were not initialized,
+ *         which can happen if XPCOM is reloaded, but did not completly
+ *         shutdown. Other error codes indicate a failure during
+ *         initialisation.
+ */
+XPCOM_API(nsresult)
+NS_InitXPCOM2(nsIServiceManager** aResult,
+              nsIFile* aBinDirectory,
+              nsIDirectoryServiceProvider* aAppFileLocationProvider);
+
+/**
+ * Initialize only minimal components of XPCOM. This ensures nsThreadManager,
+ * logging, and timers will work.
+ */
+XPCOM_API(nsresult)
+NS_InitMinimalXPCOM();
+
+/**
+ * Shutdown XPCOM. You must call this method after you are finished
+ * using xpcom.
+ *
+ * @param aServMgr          The service manager which was returned by NS_InitXPCOM.
+ *                          This will release servMgr.  You may pass null.
+ *
+ * @return NS_OK for success;
+ *         other error codes indicate a failure during initialisation.
+ */
+XPCOM_API(nsresult) NS_ShutdownXPCOM(nsIServiceManager* aServMgr);
+
+
+/**
+ * Public Method to access to the service manager.
+ *
+ * @param aResult Interface pointer to the service manager
+ *
+ * @return NS_OK for success;
+ *         other error codes indicate a failure during initialisation.
+ */
+XPCOM_API(nsresult) NS_GetServiceManager(nsIServiceManager** aResult);
+
+/**
+ * Public Method to access to the component manager.
+ *
+ * @param aResult Interface pointer to the service
+ *
+ * @return NS_OK for success;
+ *         other error codes indicate a failure during initialisation.
+ */
+XPCOM_API(nsresult) NS_GetComponentManager(nsIComponentManager** aResult);
+
+
+/**
+ * Public Method to access to the component registration manager.
+ *
+ * @param aResult Interface pointer to the service
+ *
+ * @return NS_OK for success;
+ *         other error codes indicate a failure during initialisation.
+ */
+XPCOM_API(nsresult) NS_GetComponentRegistrar(nsIComponentRegistrar** aResult);
+
+/**
+ * Public Method to access to the memory manager.  See nsIMemory
+ *
+ * @param aResult Interface pointer to the memory manager
+ *
+ * @return NS_OK for success;
+ *         other error codes indicate a failure during initialisation.
+ */
+XPCOM_API(nsresult) NS_GetMemoryManager(nsIMemory** aResult);
+
+/**
+ * Public Method to create an instance of a nsIFile.  This function
+ * may be called prior to NS_InitXPCOM.
+ *
+ *   @param aPath
+ *       A string which specifies a full file path to a
+ *       location.  Relative paths will be treated as an
+ *       error (NS_ERROR_FILE_UNRECOGNIZED_PATH).
+ *       |NS_NewNativeLocalFile|'s path must be in the
+ *       filesystem charset.
+ *   @param aFollowLinks
+ *       This attribute will determine if the nsLocalFile will auto
+ *       resolve symbolic links.  By default, this value will be false
+ *       on all non unix systems.  On unix, this attribute is effectively
+ *       a noop.
+ * @param aResult Interface pointer to a new instance of an nsIFile
+ *
+ * @return NS_OK for success;
+ *         other error codes indicate a failure.
+ */
+
+#ifdef __cplusplus
+
+XPCOM_API(nsresult) NS_NewLocalFile(const nsAString& aPath,
+                                    bool aFollowLinks,
+                                    nsIFile** aResult);
+
+XPCOM_API(nsresult) NS_NewNativeLocalFile(const nsACString& aPath,
+                                          bool aFollowLinks,
+                                          nsIFile** aResult);
+
+#endif
+
+/**
+ * Allocator functions for the standalone glue.
+ * Do not use outside the xpcom glue code.
+ * Use moz_xmalloc/moz_xrealloc/free, or new/delete instead.
+ */
+#ifdef XPCOM_GLUE
+/**
+ * Allocates a block of memory of a particular size. If the memory cannot
+ * be allocated (because of an out-of-memory condition), the process aborts.
+ *
+ * @param aSize  The size of the block to allocate
+ * @result       The block of memory
+ * @note         This function is thread-safe.
+ */
+XPCOM_API(void*) NS_Alloc(size_t aSize);
+
+/**
+ * Reallocates a block of memory to a new size.
+ *
+ * @param aPtr    The block of memory to reallocate. This block must originally
+                  have been allocated by NS_Alloc or NS_Realloc
+ * @param aSize   The new size. If 0, frees the block like NS_Free
+ * @result        The reallocated block of memory
+ * @note          This function is thread-safe.
+ *
+ * If aPtr is null, this function behaves like NS_Alloc.
+ * If s is the size of the block to which aPtr points, the first min(s, size)
+ * bytes of aPtr's block are copied to the new block. If the allocation
+ * succeeds, aPtr is freed and a pointer to the new block is returned. If the
+ * allocation fails, the process aborts.
+ */
+XPCOM_API(void*) NS_Realloc(void* aPtr, size_t aSize);
+
+/**
+ * Frees a block of memory. Null is a permissible value, in which case no
+ * action is taken.
+ *
+ * @param aPtr  The block of memory to free. This block must originally have
+ *              been allocated by NS_Alloc or NS_Realloc
+ * @note        This function is thread-safe.
+ */
+XPCOM_API(void) NS_Free(void* aPtr);
+#else
+#define NS_Alloc moz_xmalloc
+#define NS_Realloc moz_xrealloc
+#define NS_Free free
+#endif
+
+/**
+ * Support for warnings, assertions, and debugging breaks.
+ */
+
+enum
+{
+  NS_DEBUG_WARNING = 0,
+  NS_DEBUG_ASSERTION = 1,
+  NS_DEBUG_BREAK = 2,
+  NS_DEBUG_ABORT = 3
+};
+
+/**
+ * Print a runtime assertion. This function is available in both debug and
+ * release builds.
+ *
+ * @note Based on the value of aSeverity and the XPCOM_DEBUG_BREAK
+ * environment variable, this function may cause the application to
+ * print the warning, print a stacktrace, break into a debugger, or abort
+ * immediately.
+ *
+ * @param aSeverity A NS_DEBUG_* value
+ * @param aStr   A readable error message (ASCII, may be null)
+ * @param aExpr  The expression evaluated (may be null)
+ * @param aFile  The source file containing the assertion (may be null)
+ * @param aLine  The source file line number (-1 indicates no line number)
+ */
+XPCOM_API(void) NS_DebugBreak(uint32_t aSeverity,
+                              const char* aStr, const char* aExpr,
+                              const char* aFile, int32_t aLine);
+
+/**
+ * Perform a stack-walk to a debugging log under various
+ * circumstances. Used to aid debugging of leaked object graphs.
+ *
+ * The NS_Log* functions are available in both debug and release
+ * builds of XPCOM, but the output will be useless unless binary
+ * debugging symbols for all modules in the stacktrace are available.
+ */
+
+/**
+ * By default, refcount logging is enabled at NS_InitXPCOM and
+ * refcount statistics are printed at NS_ShutdownXPCOM. NS_LogInit and
+ * NS_LogTerm allow applications to enable logging earlier and delay
+ * printing of logging statistics. They should always be used as a
+ * matched pair.
+ */
+XPCOM_API(void) NS_LogInit();
+
+XPCOM_API(void) NS_LogTerm();
+
+#ifdef __cplusplus
+/**
+ * A helper class that calls NS_LogInit in its constructor and
+ * NS_LogTerm in its destructor.
+ */
+
+class ScopedLogging
+{
+public:
+    ScopedLogging()
+    {
+        NS_LogInit();
+    }
+
+    ~ScopedLogging()
+    {
+        NS_LogTerm();
+    }
+};
+#endif
+
+/**
+ * Log construction and destruction of objects. Processing tools can use the
+ * stacktraces printed by these functions to identify objects that are being
+ * leaked.
+ *
+ * @param aPtr          A pointer to the concrete object.
+ * @param aTypeName     The class name of the type
+ * @param aInstanceSize The size of the type
+ */
+
+XPCOM_API(void) NS_LogCtor(void* aPtr, const char* aTypeName,
+                           uint32_t aInstanceSize);
+
+XPCOM_API(void) NS_LogDtor(void* aPtr, const char* aTypeName,
+                           uint32_t aInstanceSize);
+
+/**
+ * Log a stacktrace when an XPCOM object's refcount is incremented or
+ * decremented. Processing tools can use the stacktraces printed by these
+ * functions to identify objects that were leaked due to XPCOM references.
+ *
+ * @param aPtr          A pointer to the concrete object
+ * @param aNewRefCnt    The new reference count.
+ * @param aTypeName     The class name of the type
+ * @param aInstanceSize The size of the type
+ */
+XPCOM_API(void) NS_LogAddRef(void* aPtr, nsrefcnt aNewRefCnt,
+                             const char* aTypeName, uint32_t aInstanceSize);
+
+XPCOM_API(void) NS_LogRelease(void* aPtr, nsrefcnt aNewRefCnt,
+                              const char* aTypeName);
+
+/**
+ * Log reference counting performed by COMPtrs. Processing tools can
+ * use the stacktraces printed by these functions to simplify reports
+ * about leaked objects generated from the data printed by
+ * NS_LogAddRef/NS_LogRelease.
+ *
+ * @param aCOMPtr the address of the COMPtr holding a strong reference
+ * @param aObject the object being referenced by the COMPtr
+ */
+
+XPCOM_API(void) NS_LogCOMPtrAddRef(void* aCOMPtr, nsISupports* aObject);
+
+XPCOM_API(void) NS_LogCOMPtrRelease(void* aCOMPtr, nsISupports* aObject);
+
+/**
+ * The XPCOM cycle collector analyzes and breaks reference cycles between
+ * participating XPCOM objects. All objects in the cycle must implement
+ * nsCycleCollectionParticipant to break cycles correctly.
+ */
+
+#ifdef __cplusplus
+
+class nsCycleCollectionParticipant;
+class nsCycleCollectingAutoRefCnt;
+
+XPCOM_API(void) NS_CycleCollectorSuspect3(void* aPtr,
+                                          nsCycleCollectionParticipant* aCp,
+                                          nsCycleCollectingAutoRefCnt* aRefCnt,
+                                          bool* aShouldDelete);
+
+#endif
+
+/**
+ * Categories (in the category manager service) used by XPCOM:
+ */
+
+/**
+ * A category which is read after component registration but before
+ * the "xpcom-startup" notifications. Each category entry is treated
+ * as the contract ID of a service which implements
+ * nsIDirectoryServiceProvider. Each directory service provider is
+ * installed in the global directory service.
+ */
+#define XPCOM_DIRECTORY_PROVIDER_CATEGORY "xpcom-directory-providers"
+
+/**
+ * A category which is read after component registration but before
+ * NS_InitXPCOM returns. Each category entry is treated as the contractID of
+ * a service: each service is instantiated, and if it implements nsIObserver
+ * the nsIObserver.observe method is called with the "xpcom-startup" topic.
+ */
+#define NS_XPCOM_STARTUP_CATEGORY "xpcom-startup"
+
+
+/**
+ * Observer topics (in the observer service) used by XPCOM:
+ */
+
+/**
+ * At XPCOM startup after component registration is complete, the
+ * following topic is notified. In order to receive this notification,
+ * component must register their contract ID in the category manager,
+ *
+ * @see NS_XPCOM_STARTUP_CATEGORY
+ */
+#define NS_XPCOM_STARTUP_OBSERVER_ID "xpcom-startup"
+
+/**
+ * At XPCOM shutdown, this topic is notified just before "xpcom-shutdown".
+ * Components should only use this to mark themselves as 'being destroyed'.
+ * Nothing should be dispatched to any event loop.
+ */
+#define NS_XPCOM_WILL_SHUTDOWN_OBSERVER_ID "xpcom-will-shutdown"
+
+/**
+ * At XPCOM shutdown, this topic is notified. All components must
+ * release any interface references to objects in other modules when
+ * this topic is notified.
+ */
+#define NS_XPCOM_SHUTDOWN_OBSERVER_ID "xpcom-shutdown"
+
+/**
+ * This topic is notified when an entry was added to a category in the
+ * category manager. The subject of the notification will be the name of
+ * the added entry as an nsISupportsCString, and the data will be the
+ * name of the category. The notification will occur on the main thread.
+ */
+#define NS_XPCOM_CATEGORY_ENTRY_ADDED_OBSERVER_ID \
+  "xpcom-category-entry-added"
+
+/**
+ * This topic is notified when an entry was removed from a category in the
+ * category manager. The subject of the notification will be the name of
+ * the removed entry as an nsISupportsCString, and the data will be the
+ * name of the category. The notification will occur on the main thread.
+ */
+#define NS_XPCOM_CATEGORY_ENTRY_REMOVED_OBSERVER_ID \
+  "xpcom-category-entry-removed"
+
+/**
+ * This topic is notified when an a category was cleared in the category
+ * manager. The subject of the notification will be the category manager,
+ * and the data will be the name of the cleared category.
+ * The notification will occur on the main thread.
+ */
+#define NS_XPCOM_CATEGORY_CLEARED_OBSERVER_ID "xpcom-category-cleared"
+
+XPCOM_API(nsresult) NS_GetDebug(nsIDebug2** aResult);
+
+#endif
diff --git a/xpcom/build/nsXPCOMCID.h b/xpcom/build/nsXPCOMCID.h
new file mode 100644
index 000000000..7219babe4
--- /dev/null
+++ b/xpcom/build/nsXPCOMCID.h
@@ -0,0 +1,185 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsXPCOMCID_h__
+#define nsXPCOMCID_h__
+
+/**
+ * XPCOM Directory Service Contract ID
+ *   The directory service provides ways to obtain file system locations. The
+ *   directory service is a singleton.
+ *
+ *   This contract supports the nsIDirectoryService and the nsIProperties
+ *   interfaces.
+ *
+ */
+#define NS_DIRECTORY_SERVICE_CONTRACTID "@mozilla.org/file/directory_service;1"
+
+/**
+ * XPCOM File
+ *   The file abstraction provides ways to obtain and access files and
+ *   directories located on the local system.
+ *
+ *   This contract supports the nsIFile interface.
+ *   This contract may also support platform specific interfaces such as
+ *   nsILocalFileMac on platforms where additional interfaces are required.
+ *
+ */
+#define NS_LOCAL_FILE_CONTRACTID "@mozilla.org/file/local;1"
+
+/**
+ * XPCOM Category Manager Contract ID
+ *   The contract supports the nsICategoryManager interface. The
+ *   category manager is a singleton.
+ * The "enumerateCategory" method of nsICategoryManager will return an object
+ * that implements nsIUTF8StringEnumerator. In addition, the enumerator will
+ * return the entries in sorted order (sorted by byte comparison).
+ */
+#define NS_CATEGORYMANAGER_CONTRACTID   "@mozilla.org/categorymanager;1"
+
+/**
+ * XPCOM Properties Object Contract ID
+ *   Simple mapping object which supports the nsIProperties interface.
+ */
+#define NS_PROPERTIES_CONTRACTID "@mozilla.org/properties;1"
+
+/**
+ * XPCOM Array Object ContractID
+ * Simple array implementation which supports the nsIArray and
+ * nsIMutableArray interfaces.
+ */
+#define NS_ARRAY_CONTRACTID  "@mozilla.org/array;1"
+
+/**
+ * Observer Service ContractID
+ * The observer service implements the global nsIObserverService object.
+ * It should be used from the main thread only.
+ */
+#define NS_OBSERVERSERVICE_CONTRACTID "@mozilla.org/observer-service;1"
+
+/**
+ * IO utilities service contract id.
+ * This guarantees implementation of nsIIOUtil.  Usable from any thread.
+ */
+#define NS_IOUTIL_CONTRACTID "@mozilla.org/io-util;1"
+
+/**
+ * Memory reporter service CID
+ */
+#define NS_MEMORY_REPORTER_MANAGER_CONTRACTID "@mozilla.org/memory-reporter-manager;1"
+
+/**
+ * Memory info dumper service CID
+ */
+#define NS_MEMORY_INFO_DUMPER_CONTRACTID "@mozilla.org/memory-info-dumper;1"
+
+/**
+ * Status reporter service CID
+ */
+#define NS_STATUS_REPORTER_MANAGER_CONTRACTID "@mozilla.org/status-reporter-manager;1"
+
+/**
+ * Cycle collector logger contract id
+ */
+#define NS_CYCLE_COLLECTOR_LOGGER_CONTRACTID "@mozilla.org/cycle-collector-logger;1"
+
+/**
+ * nsMessageLoop contract id
+ */
+#define NS_MESSAGE_LOOP_CONTRACTID "@mozilla.org/message-loop;1"
+
+#define NS_COMPARTMENT_INFO_CONTRACTID "@mozilla.org/compartment-info;1"
+
+/**
+ * The following are the CIDs and Contract IDs of the nsISupports wrappers for
+ * primative types.
+ */
+#define NS_SUPPORTS_ID_CID \
+{ 0xacf8dc40, 0x4a25, 0x11d3, \
+{ 0x98, 0x90, 0x0, 0x60, 0x8, 0x96, 0x24, 0x22 } }
+#define NS_SUPPORTS_ID_CONTRACTID "@mozilla.org/supports-id;1"
+
+#define NS_SUPPORTS_CSTRING_CID \
+{ 0xacf8dc41, 0x4a25, 0x11d3, \
+{ 0x98, 0x90, 0x0, 0x60, 0x8, 0x96, 0x24, 0x22 } }
+#define NS_SUPPORTS_CSTRING_CONTRACTID "@mozilla.org/supports-cstring;1"
+
+#define NS_SUPPORTS_STRING_CID \
+{ 0xacf8dc42, 0x4a25, 0x11d3, \
+{ 0x98, 0x90, 0x0, 0x60, 0x8, 0x96, 0x24, 0x22 } }
+#define NS_SUPPORTS_STRING_CONTRACTID "@mozilla.org/supports-string;1"
+
+#define NS_SUPPORTS_PRBOOL_CID \
+{ 0xacf8dc43, 0x4a25, 0x11d3, \
+{ 0x98, 0x90, 0x0, 0x60, 0x8, 0x96, 0x24, 0x22 } }
+#define NS_SUPPORTS_PRBOOL_CONTRACTID "@mozilla.org/supports-PRBool;1"
+
+#define NS_SUPPORTS_PRUINT8_CID \
+{ 0xacf8dc44, 0x4a25, 0x11d3, \
+{ 0x98, 0x90, 0x0, 0x60, 0x8, 0x96, 0x24, 0x22 } }
+#define NS_SUPPORTS_PRUINT8_CONTRACTID "@mozilla.org/supports-PRUint8;1"
+
+#define NS_SUPPORTS_PRUINT16_CID \
+{ 0xacf8dc46, 0x4a25, 0x11d3, \
+{ 0x98, 0x90, 0x0, 0x60, 0x8, 0x96, 0x24, 0x22 } }
+#define NS_SUPPORTS_PRUINT16_CONTRACTID "@mozilla.org/supports-PRUint16;1"
+
+#define NS_SUPPORTS_PRUINT32_CID \
+{ 0xacf8dc47, 0x4a25, 0x11d3, \
+{ 0x98, 0x90, 0x0, 0x60, 0x8, 0x96, 0x24, 0x22 } }
+#define NS_SUPPORTS_PRUINT32_CONTRACTID "@mozilla.org/supports-PRUint32;1"
+
+#define NS_SUPPORTS_PRUINT64_CID \
+{ 0xacf8dc48, 0x4a25, 0x11d3, \
+{ 0x98, 0x90, 0x0, 0x60, 0x8, 0x96, 0x24, 0x22 } }
+#define NS_SUPPORTS_PRUINT64_CONTRACTID "@mozilla.org/supports-PRUint64;1"
+
+#define NS_SUPPORTS_PRTIME_CID \
+{ 0xacf8dc49, 0x4a25, 0x11d3, \
+{ 0x98, 0x90, 0x0, 0x60, 0x8, 0x96, 0x24, 0x22 } }
+#define NS_SUPPORTS_PRTIME_CONTRACTID "@mozilla.org/supports-PRTime;1"
+
+#define NS_SUPPORTS_CHAR_CID \
+{ 0xacf8dc4a, 0x4a25, 0x11d3, \
+{ 0x98, 0x90, 0x0, 0x60, 0x8, 0x96, 0x24, 0x22 } }
+#define NS_SUPPORTS_CHAR_CONTRACTID "@mozilla.org/supports-char;1"
+
+#define NS_SUPPORTS_PRINT16_CID \
+{ 0xacf8dc4b, 0x4a25, 0x11d3, \
+{ 0x98, 0x90, 0x0, 0x60, 0x8, 0x96, 0x24, 0x22 } }
+#define NS_SUPPORTS_PRINT16_CONTRACTID "@mozilla.org/supports-PRInt16;1"
+
+#define NS_SUPPORTS_PRINT32_CID \
+{ 0xacf8dc4c, 0x4a25, 0x11d3, \
+{ 0x98, 0x90, 0x0, 0x60, 0x8, 0x96, 0x24, 0x22 } }
+#define NS_SUPPORTS_PRINT32_CONTRACTID "@mozilla.org/supports-PRInt32;1"
+
+#define NS_SUPPORTS_PRINT64_CID \
+{ 0xacf8dc4d, 0x4a25, 0x11d3, \
+{ 0x98, 0x90, 0x0, 0x60, 0x8, 0x96, 0x24, 0x22 } }
+#define NS_SUPPORTS_PRINT64_CONTRACTID "@mozilla.org/supports-PRInt64;1"
+
+#define NS_SUPPORTS_FLOAT_CID \
+{ 0xcbf86870, 0x4ac0, 0x11d3, \
+{ 0xba, 0xea, 0x0, 0x80, 0x5f, 0x8a, 0x5d, 0xd7 } }
+#define NS_SUPPORTS_FLOAT_CONTRACTID "@mozilla.org/supports-float;1"
+
+#define NS_SUPPORTS_DOUBLE_CID \
+{ 0xcbf86871, 0x4ac0, 0x11d3, \
+{ 0xba, 0xea, 0x0, 0x80, 0x5f, 0x8a, 0x5d, 0xd7 } }
+#define NS_SUPPORTS_DOUBLE_CONTRACTID "@mozilla.org/supports-double;1"
+
+#define NS_SUPPORTS_VOID_CID \
+{ 0xaf10f3e0, 0x568d, 0x11d3, \
+{ 0xba, 0xf8, 0x0, 0x80, 0x5f, 0x8a, 0x5d, 0xd7 } }
+#define NS_SUPPORTS_VOID_CONTRACTID "@mozilla.org/supports-void;1"
+
+#define NS_SUPPORTS_INTERFACE_POINTER_CID \
+{ 0xA99FEBBA, 0x1DD1, 0x11B2, \
+{ 0xA9, 0x43, 0xB0, 0x23, 0x34, 0xA6, 0xD0, 0x83 } }
+#define NS_SUPPORTS_INTERFACE_POINTER_CONTRACTID "@mozilla.org/supports-interface-pointer;1"
+
+#endif
diff --git a/xpcom/build/nsXPCOMCIDInternal.h b/xpcom/build/nsXPCOMCIDInternal.h
new file mode 100644
index 000000000..c9f7fb6f3
--- /dev/null
+++ b/xpcom/build/nsXPCOMCIDInternal.h
@@ -0,0 +1,54 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsXPCOMCIDInternal_h__
+#define nsXPCOMCIDInternal_h__
+
+#include "nsXPCOMCID.h"
+
+/**
+ * A hashtable-based property bag component.
+ * @implements nsIWritablePropertyBag, nsIWritablePropertyBag2
+ */
+#define NS_HASH_PROPERTY_BAG_CID \
+{ 0x678c50b8, 0x6bcb, 0x4ad0, \
+{ 0xb9, 0xb8, 0xc8, 0x11, 0x75, 0x95, 0x51, 0x99 } }
+#define NS_HASH_PROPERTY_BAG_CONTRACTID "@mozilla.org/hash-property-bag;1"
+
+/**
+ * Factory for creating nsIUnicharInputStream
+ * @implements nsIUnicharInputStreamFactory
+ * @note nsIUnicharInputStream instances cannot be created via
+ *       createInstance. Code must use one of the custom factory methods.
+ */
+#define NS_SIMPLE_UNICHAR_STREAM_FACTORY_CONTRACTID \
+  "@mozilla.org/xpcom/simple-unichar-stream-factory;1"
+
+/**
+ * The global thread manager service.  This component is a singleton.
+ * @implements nsIThreadManager
+ */
+#define NS_THREADMANAGER_CONTRACTID "@mozilla.org/thread-manager;1"
+
+/**
+ * A thread pool component.
+ * @implements nsIThreadPool
+ */
+#define NS_THREADPOOL_CONTRACTID "@mozilla.org/thread-pool;1"
+
+/**
+ * The contract id for the nsIXULAppInfo service.
+ */
+#define XULAPPINFO_SERVICE_CONTRACTID \
+  "@mozilla.org/xre/app-info;1"
+
+/**
+ * The contract id for the nsIXULRuntime service.
+ */
+#define XULRUNTIME_SERVICE_CONTRACTID \
+  "@mozilla.org/xre/runtime;1"
+
+#endif  // nsXPCOMCIDInternal_h__
diff --git a/xpcom/build/nsXPCOMPrivate.h b/xpcom/build/nsXPCOMPrivate.h
new file mode 100644
index 000000000..99a994013
--- /dev/null
+++ b/xpcom/build/nsXPCOMPrivate.h
@@ -0,0 +1,317 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsXPCOMPrivate_h__
+#define nsXPCOMPrivate_h__
+
+#include "nscore.h"
+#include "nsXPCOM.h"
+#include "nsXPCOMStrings.h"
+#include "xptcall.h"
+
+class nsStringContainer;
+class nsCStringContainer;
+class nsPurpleBufferEntry;
+
+/**
+ * During this shutdown notification all threads which run XPCOM code must
+ * be joined.
+ */
+#define NS_XPCOM_SHUTDOWN_THREADS_OBSERVER_ID "xpcom-shutdown-threads"
+
+/**
+ * During this shutdown notification all module loaders must unload XPCOM
+ * modules.
+ */
+#define NS_XPCOM_SHUTDOWN_LOADERS_OBSERVER_ID "xpcom-shutdown-loaders"
+
+// PUBLIC
+typedef nsresult   (*InitFunc)(nsIServiceManager** aResult,
+                               nsIFile* aBinDirectory,
+                               nsIDirectoryServiceProvider* aAppFileLocationProvider);
+typedef nsresult   (*ShutdownFunc)(nsIServiceManager* aServMgr);
+typedef nsresult   (*GetServiceManagerFunc)(nsIServiceManager** aResult);
+typedef nsresult   (*GetComponentManagerFunc)(nsIComponentManager** aResult);
+typedef nsresult   (*GetComponentRegistrarFunc)(nsIComponentRegistrar** aResult);
+typedef nsresult   (*GetMemoryManagerFunc)(nsIMemory** aResult);
+typedef nsresult   (*NewLocalFileFunc)(const nsAString& aPath,
+                                       bool aFollowLinks, nsIFile** aResult);
+typedef nsresult   (*NewNativeLocalFileFunc)(const nsACString& aPath,
+                                             bool aFollowLinks,
+                                             nsIFile** aResult);
+
+typedef nsresult   (*GetDebugFunc)(nsIDebug2** aResult);
+
+typedef nsresult   (*StringContainerInitFunc)(nsStringContainer&);
+typedef nsresult   (*StringContainerInit2Func)(nsStringContainer&,
+                                               const char16_t*,
+                                               uint32_t, uint32_t);
+typedef void       (*StringContainerFinishFunc)(nsStringContainer&);
+typedef uint32_t   (*StringGetDataFunc)(const nsAString&, const char16_t**,
+                                        bool*);
+typedef uint32_t   (*StringGetMutableDataFunc)(nsAString&, uint32_t,
+                                               char16_t**);
+typedef char16_t*  (*StringCloneDataFunc)(const nsAString&);
+typedef nsresult   (*StringSetDataFunc)(nsAString&, const char16_t*, uint32_t);
+typedef nsresult   (*StringSetDataRangeFunc)(nsAString&, uint32_t, uint32_t,
+                                             const char16_t*, uint32_t);
+typedef nsresult   (*StringCopyFunc)(nsAString&, const nsAString&);
+typedef void       (*StringSetIsVoidFunc)(nsAString&, const bool);
+typedef bool       (*StringGetIsVoidFunc)(const nsAString&);
+
+typedef nsresult   (*CStringContainerInitFunc)(nsCStringContainer&);
+typedef nsresult   (*CStringContainerInit2Func)(nsCStringContainer&,
+                                                const char*,
+                                                uint32_t, uint32_t);
+typedef void       (*CStringContainerFinishFunc)(nsCStringContainer&);
+typedef uint32_t   (*CStringGetDataFunc)(const nsACString&, const char**,
+                                         bool*);
+typedef uint32_t   (*CStringGetMutableDataFunc)(nsACString&, uint32_t, char**);
+typedef char*      (*CStringCloneDataFunc)(const nsACString&);
+typedef nsresult   (*CStringSetDataFunc)(nsACString&, const char*, uint32_t);
+typedef nsresult   (*CStringSetDataRangeFunc)(nsACString&, uint32_t, uint32_t,
+                                              const char*, uint32_t);
+typedef nsresult   (*CStringCopyFunc)(nsACString&, const nsACString&);
+typedef void       (*CStringSetIsVoidFunc)(nsACString&, const bool);
+typedef bool       (*CStringGetIsVoidFunc)(const nsACString&);
+
+typedef nsresult   (*CStringToUTF16)(const nsACString&, nsCStringEncoding,
+                                     nsAString&);
+typedef nsresult   (*UTF16ToCString)(const nsAString&, nsCStringEncoding,
+                                     nsACString&);
+
+typedef void*      (*AllocFunc)(size_t aSize);
+typedef void*      (*ReallocFunc)(void* aPtr, size_t aSize);
+typedef void       (*FreeFunc)(void* aPtr);
+
+typedef void       (*DebugBreakFunc)(uint32_t aSeverity,
+                                     const char* aStr, const char* aExpr,
+                                     const char* aFile, int32_t aLine);
+
+typedef void       (*xpcomVoidFunc)();
+typedef void       (*LogAddRefFunc)(void*, nsrefcnt, const char*, uint32_t);
+typedef void       (*LogReleaseFunc)(void*, nsrefcnt, const char*);
+typedef void       (*LogCtorFunc)(void*, const char*, uint32_t);
+typedef void       (*LogCOMPtrFunc)(void*, nsISupports*);
+
+typedef nsresult   (*GetXPTCallStubFunc)(REFNSIID, nsIXPTCProxy*,
+                                         nsISomeInterface**);
+typedef void       (*DestroyXPTCallStubFunc)(nsISomeInterface*);
+typedef nsresult   (*InvokeByIndexFunc)(nsISupports*, uint32_t, uint32_t,
+                                        nsXPTCVariant*);
+typedef bool       (*CycleCollectorFunc)(nsISupports*);
+typedef nsPurpleBufferEntry*
+                   (*CycleCollectorSuspect2Func)(void*,
+                                                 nsCycleCollectionParticipant*);
+typedef bool       (*CycleCollectorForget2Func)(nsPurpleBufferEntry*);
+typedef void       (*CycleCollectorSuspect3Func)(void*,
+                                                 nsCycleCollectionParticipant*,
+                                                 nsCycleCollectingAutoRefCnt*,
+                                                 bool*);
+// PRIVATE AND DEPRECATED
+typedef NS_CALLBACK(XPCOMExitRoutine)(void);
+
+typedef nsresult   (*RegisterXPCOMExitRoutineFunc)(XPCOMExitRoutine aExitRoutine,
+                                                   uint32_t aPriority);
+typedef nsresult   (*UnregisterXPCOMExitRoutineFunc)(XPCOMExitRoutine aExitRoutine);
+
+typedef struct XPCOMFunctions
+{
+  uint32_t version;
+  uint32_t size;
+
+  InitFunc init;
+  ShutdownFunc shutdown;
+  GetServiceManagerFunc getServiceManager;
+  GetComponentManagerFunc getComponentManager;
+  GetComponentRegistrarFunc getComponentRegistrar;
+  GetMemoryManagerFunc getMemoryManager;
+  NewLocalFileFunc newLocalFile;
+  NewNativeLocalFileFunc newNativeLocalFile;
+
+  RegisterXPCOMExitRoutineFunc registerExitRoutine;
+  UnregisterXPCOMExitRoutineFunc unregisterExitRoutine;
+
+  // Added for Mozilla 1.5
+  GetDebugFunc getDebug;
+  void* getTraceRefcnt;
+
+  // Added for Mozilla 1.7
+  StringContainerInitFunc stringContainerInit;
+  StringContainerFinishFunc stringContainerFinish;
+  StringGetDataFunc stringGetData;
+  StringSetDataFunc stringSetData;
+  StringSetDataRangeFunc stringSetDataRange;
+  StringCopyFunc stringCopy;
+  CStringContainerInitFunc cstringContainerInit;
+  CStringContainerFinishFunc cstringContainerFinish;
+  CStringGetDataFunc cstringGetData;
+  CStringSetDataFunc cstringSetData;
+  CStringSetDataRangeFunc cstringSetDataRange;
+  CStringCopyFunc cstringCopy;
+  CStringToUTF16 cstringToUTF16;
+  UTF16ToCString utf16ToCString;
+  StringCloneDataFunc stringCloneData;
+  CStringCloneDataFunc cstringCloneData;
+
+  // Added for Mozilla 1.8
+  AllocFunc allocFunc;
+  ReallocFunc reallocFunc;
+  FreeFunc freeFunc;
+  StringContainerInit2Func stringContainerInit2;
+  CStringContainerInit2Func cstringContainerInit2;
+  StringGetMutableDataFunc stringGetMutableData;
+  CStringGetMutableDataFunc cstringGetMutableData;
+  void* init3; // obsolete
+
+  // Added for Mozilla 1.9
+  DebugBreakFunc debugBreakFunc;
+  xpcomVoidFunc logInitFunc;
+  xpcomVoidFunc logTermFunc;
+  LogAddRefFunc logAddRefFunc;
+  LogReleaseFunc logReleaseFunc;
+  LogCtorFunc logCtorFunc;
+  LogCtorFunc logDtorFunc;
+  LogCOMPtrFunc logCOMPtrAddRefFunc;
+  LogCOMPtrFunc logCOMPtrReleaseFunc;
+  GetXPTCallStubFunc getXPTCallStubFunc;
+  DestroyXPTCallStubFunc destroyXPTCallStubFunc;
+  InvokeByIndexFunc invokeByIndexFunc;
+  CycleCollectorFunc cycleSuspectFunc; // obsolete: use cycleSuspect3Func
+  CycleCollectorFunc cycleForgetFunc; // obsolete
+  StringSetIsVoidFunc stringSetIsVoid;
+  StringGetIsVoidFunc stringGetIsVoid;
+  CStringSetIsVoidFunc cstringSetIsVoid;
+  CStringGetIsVoidFunc cstringGetIsVoid;
+
+  // Added for Mozilla 1.9.1
+  CycleCollectorSuspect2Func cycleSuspect2Func; // obsolete: use cycleSuspect3Func
+  CycleCollectorForget2Func cycleForget2Func; // obsolete
+
+  CycleCollectorSuspect3Func cycleSuspect3Func;
+
+} XPCOMFunctions;
+
+typedef nsresult (*GetFrozenFunctionsFunc)(XPCOMFunctions* aEntryPoints,
+                                           const char* aLibraryPath);
+XPCOM_API(nsresult) NS_GetFrozenFunctions(XPCOMFunctions* aEntryPoints,
+                                          const char* aLibraryPath);
+
+
+namespace mozilla {
+
+/**
+ * Shutdown XPCOM. You must call this method after you are finished
+ * using xpcom.
+ *
+ * @param aServMgr          The service manager which was returned by NS_InitXPCOM.
+ *                          This will release servMgr.  You may pass null.
+ *
+ * @return NS_OK for success;
+ *         other error codes indicate a failure during shutdown
+ *
+ */
+nsresult
+ShutdownXPCOM(nsIServiceManager* aServMgr);
+
+void SetICUMemoryFunctions();
+
+/**
+ * C++ namespaced version of NS_LogTerm.
+ */
+void LogTerm();
+
+} // namespace mozilla
+
+
+// think hard before changing this
+#define XPCOM_GLUE_VERSION 1
+
+
+/* XPCOM Specific Defines
+ *
+ * XPCOM_DLL              - name of the loadable xpcom library on disk.
+ * XUL_DLL                - name of the loadable XUL library on disk
+ * XPCOM_SEARCH_KEY       - name of the environment variable that can be
+ *                          modified to include additional search paths.
+ * GRE_CONF_NAME          - Name of the GRE Configuration file
+ */
+
+#if defined(XP_WIN32)
+
+#define XPCOM_SEARCH_KEY  "PATH"
+#define GRE_CONF_NAME     "gre.config"
+#define GRE_WIN_REG_LOC   L"Software\\mozilla.org\\GRE"
+#define XPCOM_DLL         XUL_DLL
+#define LXPCOM_DLL        LXUL_DLL
+#define XUL_DLL           "xul.dll"
+#define LXUL_DLL          L"xul.dll"
+
+#else // Unix
+#include <limits.h> // for PATH_MAX
+
+#define XPCOM_DLL         XUL_DLL
+
+// you have to love apple..
+#ifdef XP_MACOSX
+#define XPCOM_SEARCH_KEY  "DYLD_LIBRARY_PATH"
+#define GRE_FRAMEWORK_NAME "XUL.framework"
+#define XUL_DLL            "XUL"
+#else
+#define XPCOM_SEARCH_KEY  "LD_LIBRARY_PATH"
+#define XUL_DLL   "libxul" MOZ_DLL_SUFFIX
+#endif
+
+#define GRE_CONF_NAME ".gre.config"
+#define GRE_CONF_PATH "/etc/gre.conf"
+#define GRE_CONF_DIR  "/etc/gre.d"
+#define GRE_USER_CONF_DIR ".gre.d"
+#endif
+
+#if defined(XP_WIN)
+  #define XPCOM_FILE_PATH_SEPARATOR       "\\"
+  #define XPCOM_ENV_PATH_SEPARATOR        ";"
+#elif defined(XP_UNIX)
+  #define XPCOM_FILE_PATH_SEPARATOR       "/"
+  #define XPCOM_ENV_PATH_SEPARATOR        ":"
+#else
+  #error need_to_define_your_file_path_separator_and_illegal_characters
+#endif
+
+#ifdef AIX
+#include <sys/param.h>
+#endif
+
+#ifndef MAXPATHLEN
+#ifdef PATH_MAX
+#define MAXPATHLEN PATH_MAX
+#elif defined(_MAX_PATH)
+#define MAXPATHLEN _MAX_PATH
+#elif defined(CCHMAXPATH)
+#define MAXPATHLEN CCHMAXPATH
+#else
+#define MAXPATHLEN 1024
+#endif
+#endif
+
+extern bool gXPCOMShuttingDown;
+extern bool gXPCOMThreadsShutDown;
+
+// Needed by the IPC layer from off the main thread
+extern char16_t* gGREBinPath;
+
+namespace mozilla {
+namespace services {
+
+/**
+ * Clears service cache, sets gXPCOMShuttingDown
+ */
+void Shutdown();
+
+} // namespace services
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/build/nsXPCOMStrings.cpp b/xpcom/build/nsXPCOMStrings.cpp
new file mode 100644
index 000000000..617edbab2
--- /dev/null
+++ b/xpcom/build/nsXPCOMStrings.cpp
@@ -0,0 +1,366 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsString.h"
+#include "nsCharTraits.h"
+
+#include "nsXPCOMStrings.h"
+#include "nsNativeCharsetUtils.h"
+
+/* ------------------------------------------------------------------------- */
+
+XPCOM_API(nsresult)
+NS_StringContainerInit(nsStringContainer& aContainer)
+{
+  NS_ASSERTION(sizeof(nsStringContainer_base) >= sizeof(nsString),
+               "nsStringContainer is not large enough");
+
+  // use placement new to avoid heap allocating nsString object
+  new (&aContainer) nsString();
+
+  return NS_OK;
+}
+
+XPCOM_API(nsresult)
+NS_StringContainerInit2(nsStringContainer& aContainer,
+                        const char16_t* aData,
+                        uint32_t aDataLength,
+                        uint32_t aFlags)
+{
+  NS_ASSERTION(sizeof(nsStringContainer_base) >= sizeof(nsString),
+               "nsStringContainer is not large enough");
+
+  if (!aData) {
+    new (&aContainer) nsString();
+  } else {
+    if (aDataLength == UINT32_MAX) {
+      if (NS_WARN_IF(aFlags & NS_STRING_CONTAINER_INIT_SUBSTRING)) {
+        return NS_ERROR_INVALID_ARG;
+      }
+      aDataLength = nsCharTraits<char16_t>::length(aData);
+    }
+
+    if (aFlags & (NS_STRING_CONTAINER_INIT_DEPEND |
+                  NS_STRING_CONTAINER_INIT_ADOPT)) {
+      uint32_t flags;
+      if (aFlags & NS_STRING_CONTAINER_INIT_SUBSTRING) {
+        flags = nsSubstring::F_NONE;
+      } else {
+        flags = nsSubstring::F_TERMINATED;
+      }
+
+      if (aFlags & NS_STRING_CONTAINER_INIT_ADOPT) {
+        flags |= nsSubstring::F_OWNED;
+      }
+
+      new (&aContainer) nsSubstring(const_cast<char16_t*>(aData),
+                                    aDataLength, flags);
+    } else {
+      new (&aContainer) nsString(aData, aDataLength);
+    }
+  }
+
+  return NS_OK;
+}
+
+XPCOM_API(void)
+NS_StringContainerFinish(nsStringContainer& aContainer)
+{
+  // call the nsString dtor
+  reinterpret_cast<nsString*>(&aContainer)->~nsString();
+}
+
+/* ------------------------------------------------------------------------- */
+
+XPCOM_API(uint32_t)
+NS_StringGetData(const nsAString& aStr, const char16_t** aData,
+                 bool* aTerminated)
+{
+  if (aTerminated) {
+    *aTerminated = aStr.IsTerminated();
+  }
+
+  *aData = aStr.BeginReading();
+  return aStr.Length();
+}
+
+XPCOM_API(uint32_t)
+NS_StringGetMutableData(nsAString& aStr, uint32_t aDataLength,
+                        char16_t** aData)
+{
+  if (aDataLength != UINT32_MAX) {
+    aStr.SetLength(aDataLength);
+    if (aStr.Length() != aDataLength) {
+      *aData = nullptr;
+      return 0;
+    }
+  }
+
+  *aData = aStr.BeginWriting();
+  return aStr.Length();
+}
+
+XPCOM_API(char16_t*)
+NS_StringCloneData(const nsAString& aStr)
+{
+  return ToNewUnicode(aStr);
+}
+
+XPCOM_API(nsresult)
+NS_StringSetData(nsAString& aStr, const char16_t* aData, uint32_t aDataLength)
+{
+  aStr.Assign(aData, aDataLength);
+  return NS_OK; // XXX report errors
+}
+
+XPCOM_API(nsresult)
+NS_StringSetDataRange(nsAString& aStr,
+                      uint32_t aCutOffset, uint32_t aCutLength,
+                      const char16_t* aData, uint32_t aDataLength)
+{
+  if (aCutOffset == UINT32_MAX) {
+    // append case
+    if (aData) {
+      aStr.Append(aData, aDataLength);
+    }
+    return NS_OK; // XXX report errors
+  }
+
+  if (aCutLength == UINT32_MAX) {
+    aCutLength = aStr.Length() - aCutOffset;
+  }
+
+  if (aData) {
+    if (aDataLength == UINT32_MAX) {
+      aStr.Replace(aCutOffset, aCutLength, nsDependentString(aData));
+    } else {
+      aStr.Replace(aCutOffset, aCutLength, Substring(aData, aDataLength));
+    }
+  } else {
+    aStr.Cut(aCutOffset, aCutLength);
+  }
+
+  return NS_OK; // XXX report errors
+}
+
+XPCOM_API(nsresult)
+NS_StringCopy(nsAString& aDest, const nsAString& aSrc)
+{
+  aDest.Assign(aSrc);
+  return NS_OK; // XXX report errors
+}
+
+XPCOM_API(void)
+NS_StringSetIsVoid(nsAString& aStr, const bool aIsVoid)
+{
+  aStr.SetIsVoid(aIsVoid);
+}
+
+XPCOM_API(bool)
+NS_StringGetIsVoid(const nsAString& aStr)
+{
+  return aStr.IsVoid();
+}
+
+/* ------------------------------------------------------------------------- */
+
+XPCOM_API(nsresult)
+NS_CStringContainerInit(nsCStringContainer& aContainer)
+{
+  NS_ASSERTION(sizeof(nsStringContainer_base) >= sizeof(nsCString),
+               "nsCStringContainer is not large enough");
+
+  // use placement new to avoid heap allocating nsCString object
+  new (&aContainer) nsCString();
+
+  return NS_OK;
+}
+
+XPCOM_API(nsresult)
+NS_CStringContainerInit2(nsCStringContainer& aContainer,
+                         const char* aData,
+                         uint32_t aDataLength,
+                         uint32_t aFlags)
+{
+  NS_ASSERTION(sizeof(nsStringContainer_base) >= sizeof(nsCString),
+               "nsStringContainer is not large enough");
+
+  if (!aData) {
+    new (&aContainer) nsCString();
+  } else {
+    if (aDataLength == UINT32_MAX) {
+      if (NS_WARN_IF(aFlags & NS_CSTRING_CONTAINER_INIT_SUBSTRING)) {
+        return NS_ERROR_INVALID_ARG;
+      }
+      aDataLength = nsCharTraits<char>::length(aData);
+    }
+
+    if (aFlags & (NS_CSTRING_CONTAINER_INIT_DEPEND |
+                  NS_CSTRING_CONTAINER_INIT_ADOPT)) {
+      uint32_t flags;
+      if (aFlags & NS_CSTRING_CONTAINER_INIT_SUBSTRING) {
+        flags = nsCSubstring::F_NONE;
+      } else {
+        flags = nsCSubstring::F_TERMINATED;
+      }
+
+      if (aFlags & NS_CSTRING_CONTAINER_INIT_ADOPT) {
+        flags |= nsCSubstring::F_OWNED;
+      }
+
+      new (&aContainer) nsCSubstring(const_cast<char*>(aData),
+                                     aDataLength, flags);
+    } else {
+      new (&aContainer) nsCString(aData, aDataLength);
+    }
+  }
+
+  return NS_OK;
+}
+
+XPCOM_API(void)
+NS_CStringContainerFinish(nsCStringContainer& aContainer)
+{
+  // call the nsCString dtor
+  reinterpret_cast<nsCString*>(&aContainer)->~nsCString();
+}
+
+/* ------------------------------------------------------------------------- */
+
+XPCOM_API(uint32_t)
+NS_CStringGetData(const nsACString& aStr, const char** aData,
+                  bool* aTerminated)
+{
+  if (aTerminated) {
+    *aTerminated = aStr.IsTerminated();
+  }
+
+  *aData = aStr.BeginReading();
+  return aStr.Length();
+}
+
+XPCOM_API(uint32_t)
+NS_CStringGetMutableData(nsACString& aStr, uint32_t aDataLength, char** aData)
+{
+  if (aDataLength != UINT32_MAX) {
+    aStr.SetLength(aDataLength);
+    if (aStr.Length() != aDataLength) {
+      *aData = nullptr;
+      return 0;
+    }
+  }
+
+  *aData = aStr.BeginWriting();
+  return aStr.Length();
+}
+
+XPCOM_API(char*)
+NS_CStringCloneData(const nsACString& aStr)
+{
+  return ToNewCString(aStr);
+}
+
+XPCOM_API(nsresult)
+NS_CStringSetData(nsACString& aStr, const char* aData, uint32_t aDataLength)
+{
+  aStr.Assign(aData, aDataLength);
+  return NS_OK; // XXX report errors
+}
+
+XPCOM_API(nsresult)
+NS_CStringSetDataRange(nsACString& aStr,
+                       uint32_t aCutOffset, uint32_t aCutLength,
+                       const char* aData, uint32_t aDataLength)
+{
+  if (aCutOffset == UINT32_MAX) {
+    // append case
+    if (aData) {
+      aStr.Append(aData, aDataLength);
+    }
+    return NS_OK; // XXX report errors
+  }
+
+  if (aCutLength == UINT32_MAX) {
+    aCutLength = aStr.Length() - aCutOffset;
+  }
+
+  if (aData) {
+    if (aDataLength == UINT32_MAX) {
+      aStr.Replace(aCutOffset, aCutLength, nsDependentCString(aData));
+    } else {
+      aStr.Replace(aCutOffset, aCutLength, Substring(aData, aDataLength));
+    }
+  } else {
+    aStr.Cut(aCutOffset, aCutLength);
+  }
+
+  return NS_OK; // XXX report errors
+}
+
+XPCOM_API(nsresult)
+NS_CStringCopy(nsACString& aDest, const nsACString& aSrc)
+{
+  aDest.Assign(aSrc);
+  return NS_OK; // XXX report errors
+}
+
+XPCOM_API(void)
+NS_CStringSetIsVoid(nsACString& aStr, const bool aIsVoid)
+{
+  aStr.SetIsVoid(aIsVoid);
+}
+
+XPCOM_API(bool)
+NS_CStringGetIsVoid(const nsACString& aStr)
+{
+  return aStr.IsVoid();
+}
+
+/* ------------------------------------------------------------------------- */
+
+XPCOM_API(nsresult)
+NS_CStringToUTF16(const nsACString& aSrc,
+                  nsCStringEncoding aSrcEncoding,
+                  nsAString& aDest)
+{
+  switch (aSrcEncoding) {
+    case NS_CSTRING_ENCODING_ASCII:
+      CopyASCIItoUTF16(aSrc, aDest);
+      break;
+    case NS_CSTRING_ENCODING_UTF8:
+      CopyUTF8toUTF16(aSrc, aDest);
+      break;
+    case NS_CSTRING_ENCODING_NATIVE_FILESYSTEM:
+      NS_CopyNativeToUnicode(aSrc, aDest);
+      break;
+    default:
+      return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  return NS_OK; // XXX report errors
+}
+
+XPCOM_API(nsresult)
+NS_UTF16ToCString(const nsAString& aSrc,
+                  nsCStringEncoding aDestEncoding,
+                  nsACString& aDest)
+{
+  switch (aDestEncoding) {
+    case NS_CSTRING_ENCODING_ASCII:
+      LossyCopyUTF16toASCII(aSrc, aDest);
+      break;
+    case NS_CSTRING_ENCODING_UTF8:
+      CopyUTF16toUTF8(aSrc, aDest);
+      break;
+    case NS_CSTRING_ENCODING_NATIVE_FILESYSTEM:
+      NS_CopyUnicodeToNative(aSrc, aDest);
+      break;
+    default:
+      return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  return NS_OK; // XXX report errors
+}
diff --git a/xpcom/build/nsXREAppData.h b/xpcom/build/nsXREAppData.h
new file mode 100644
index 000000000..fbc7adb8f
--- /dev/null
+++ b/xpcom/build/nsXREAppData.h
@@ -0,0 +1,164 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsXREAppData_h
+#define nsXREAppData_h
+
+#include <stdint.h>
+#include "mozilla/Attributes.h"
+
+class nsIFile;
+
+#if defined(XP_WIN) && defined(MOZ_SANDBOX)
+namespace sandbox {
+class BrokerServices;
+}
+#endif
+
+/**
+ * Application-specific data needed to start the apprunner.
+ *
+ * @note When this structure is allocated and manipulated by XRE_CreateAppData,
+ *       string fields will be allocated with moz_xmalloc, and interface pointers
+ *       are strong references.
+ */
+struct nsXREAppData
+{
+  /**
+   * This should be set to sizeof(nsXREAppData). This structure may be
+   * extended in future releases, and this ensures that binary compatibility
+   * is maintained.
+   */
+  uint32_t size;
+
+  /**
+   * The directory of the application to be run. May be null if the
+   * xulrunner and the app are installed into the same directory.
+   */
+  nsIFile* MOZ_NON_OWNING_REF directory;
+
+  /**
+   * The name of the application vendor. This must be ASCII, and is normally
+   * mixed-case, e.g. "Mozilla". Optional (may be null), but highly
+   * recommended. Must not be the empty string.
+   */
+  const char* vendor;
+
+  /**
+   * The name of the application. This must be ASCII, and is normally
+   * mixed-case, e.g. "Firefox". Required (must not be null or an empty
+   * string).
+   */
+  const char* name;
+
+  /**
+   * The internal name of the application for remoting purposes. When left
+   * unspecified, "name" is used instead. This must be ASCII, and is normally
+   * lowercase, e.g. "firefox". Optional (may be null but not an empty string).
+   */
+  const char* remotingName;
+
+  /**
+   * The major version, e.g. "0.8.0+". Optional (may be null), but
+   * required for advanced application features such as the extension
+   * manager and update service. Must not be the empty string.
+   */
+  const char* version;
+
+  /**
+   * The application's build identifier, e.g. "2004051604"
+   */
+  const char* buildID;
+
+  /**
+   * The application's UUID. Used by the extension manager to determine
+   * compatible extensions. Optional, but required for advanced application
+   * features such as the extension manager and update service.
+   *
+   * This has traditionally been in the form
+   * "{AAAAAAAA-BBBB-CCCC-DDDD-EEEEEEEEEEEE}" but for new applications
+   * a more readable form is encouraged: "appname@vendor.tld". Only
+   * the following characters are allowed: a-z A-Z 0-9 - . @ _ { } *
+   */
+  const char* ID;
+
+  /**
+   * The copyright information to print for the -h commandline flag,
+   * e.g. "Copyright (c) 2003 mozilla.org".
+   */
+  const char* copyright;
+
+  /**
+   * Combination of NS_XRE_ prefixed flags (defined below).
+   */
+  uint32_t flags;
+
+  /**
+   * The location of the XRE. XRE_main may not be able to figure this out
+   * programatically.
+   */
+  nsIFile* MOZ_NON_OWNING_REF xreDirectory;
+
+  /**
+   * The minimum/maximum compatible XRE version.
+   */
+  const char* minVersion;
+  const char* maxVersion;
+
+  /**
+   * The server URL to send crash reports to.
+   */
+  const char* crashReporterURL;
+
+  /**
+   * The profile directory that will be used. Optional (may be null). Must not
+   * be the empty string, must be ASCII. The path is split into components
+   * along the path separator characters '/' and '\'.
+   *
+   * The application data directory ("UAppData", see below) is normally
+   * composed as follows, where $HOME is platform-specific:
+   *
+   *   UAppData = $HOME[/$vendor]/$name
+   *
+   * If present, the 'profile' string will be used instead of the combination of
+   * vendor and name as follows:
+   *
+   *   UAppData = $HOME/$profile
+   */
+  const char* profile;
+
+  /**
+   * The application name to use in the User Agent string.
+   */
+  const char* UAName;
+
+#if defined(XP_WIN) && defined(MOZ_SANDBOX)
+  /**
+   * Chromium sandbox BrokerServices.
+   */
+  sandbox::BrokerServices* sandboxBrokerServices;
+#endif
+};
+
+/**
+ * Indicates whether or not the profile migrator service may be
+ * invoked at startup when creating a profile.
+ */
+#define NS_XRE_ENABLE_PROFILE_MIGRATOR (1 << 1)
+
+/**
+ * Indicates the Windows DLL Blocklist initialized properly. For testing
+ * purposes only. Set in nsBrowserApp on startup, automated tests then
+ * check the result.
+ */
+#define NS_XRE_DLL_BLOCKLIST_ENABLED (1 << 2)
+
+/**
+ * Indicates whether or not to use Breakpad crash reporting.
+ */
+#define NS_XRE_ENABLE_CRASH_REPORTER (1 << 3)
+
+#endif // nsXREAppData_h
diff --git a/xpcom/build/nsXULAppAPI.h b/xpcom/build/nsXULAppAPI.h
new file mode 100644
index 000000000..426a58f06
--- /dev/null
+++ b/xpcom/build/nsXULAppAPI.h
@@ -0,0 +1,538 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef _nsXULAppAPI_h__
+#define _nsXULAppAPI_h__
+
+#include "nsID.h"
+#include "xrecore.h"
+#include "nsXPCOM.h"
+#include "nsISupports.h"
+#include "mozilla/Logging.h"
+#include "nsXREAppData.h"
+#include "js/TypeDecls.h"
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Vector.h"
+#include "mozilla/TimeStamp.h"
+#include "XREChildData.h"
+#include "XREShellData.h"
+
+/**
+ * A directory service key which provides the platform-correct "application
+ * data" directory as follows, where $name and $vendor are as defined above and
+ * $vendor is optional:
+ *
+ * Windows:
+ *   HOME = Documents and Settings\$USER\Application Data
+ *   UAppData = $HOME[\$vendor]\$name
+ *
+ * Unix:
+ *   HOME = ~
+ *   UAppData = $HOME/.[$vendor/]$name
+ *
+ * Mac:
+ *   HOME = ~
+ *   UAppData = $HOME/Library/Application Support/$name
+ *
+ * Note that the "profile" member above will change the value of UAppData as
+ * follows:
+ *
+ * Windows:
+ *   UAppData = $HOME\$profile
+ *
+ * Unix:
+ *   UAppData = $HOME/.$profile
+ *
+ * Mac:
+ *   UAppData = $HOME/Library/Application Support/$profile
+ */
+#define XRE_USER_APP_DATA_DIR "UAppData"
+
+/**
+ * A directory service key which provides a list of all enabled extension
+ * directories and files (packed XPIs).  The list includes compatible
+ * platform-specific extension subdirectories.
+ *
+ * @note The directory list will have no members when the application is
+ *       launched in safe mode.
+ */
+#define XRE_EXTENSIONS_DIR_LIST "XREExtDL"
+
+/**
+ * A directory service key which provides the executable file used to
+ * launch the current process.  This is the same value returned by the
+ * XRE_GetBinaryPath function defined below.
+ */
+#define XRE_EXECUTABLE_FILE "XREExeF"
+
+/**
+ * A directory service key which specifies the profile
+ * directory. Unlike the NS_APP_USER_PROFILE_50_DIR key, this key may
+ * be available when the profile hasn't been "started", or after is
+ * has been shut down. If the application is running without a
+ * profile, such as when showing the profile manager UI, this key will
+ * not be available. This key is provided by the XUL apprunner or by
+ * the aAppDirProvider object passed to XRE_InitEmbedding.
+ */
+#define NS_APP_PROFILE_DIR_STARTUP "ProfDS"
+
+/**
+ * A directory service key which specifies the profile
+ * directory. Unlike the NS_APP_USER_PROFILE_LOCAL_50_DIR key, this key may
+ * be available when the profile hasn't been "started", or after is
+ * has been shut down. If the application is running without a
+ * profile, such as when showing the profile manager UI, this key will
+ * not be available. This key is provided by the XUL apprunner or by
+ * the aAppDirProvider object passed to XRE_InitEmbedding.
+ */
+#define NS_APP_PROFILE_LOCAL_DIR_STARTUP "ProfLDS"
+
+/**
+ * A directory service key which specifies the system extension
+ * parent directory containing platform-specific extensions.
+ * This key may not be available on all platforms.
+ */
+#define XRE_SYS_LOCAL_EXTENSION_PARENT_DIR "XRESysLExtPD"
+
+/**
+ * A directory service key which specifies the system extension
+ * parent directory containing platform-independent extensions.
+ * This key may not be available on all platforms.
+ * Additionally, the directory may be equal to that returned by
+ * XRE_SYS_LOCAL_EXTENSION_PARENT_DIR on some platforms.
+ */
+#define XRE_SYS_SHARE_EXTENSION_PARENT_DIR "XRESysSExtPD"
+
+#if defined(XP_UNIX) || defined(XP_MACOSX)
+/**
+ * Directory service keys for the system-wide and user-specific
+ * directories where host manifests used by the WebExtensions
+ * native messaging feature are found.
+ */
+#define XRE_SYS_NATIVE_MESSAGING_MANIFESTS "XRESysNativeMessaging"
+#define XRE_USER_NATIVE_MESSAGING_MANIFESTS "XREUserNativeMessaging"
+#endif
+
+/**
+ * A directory service key which specifies the user system extension
+ * parent directory.
+ */
+#define XRE_USER_SYS_EXTENSION_DIR "XREUSysExt"
+
+/**
+ * A directory service key which specifies the distribution specific files for
+ * the application.
+ */
+#define XRE_APP_DISTRIBUTION_DIR "XREAppDist"
+
+/**
+ * A directory service key which specifies the location for system add-ons.
+ */
+#define XRE_APP_FEATURES_DIR "XREAppFeat"
+
+/**
+ * A directory service key which specifies the location for app dir add-ons.
+ * Should be a synonym for XCurProcD everywhere except in tests.
+ */
+#define XRE_ADDON_APP_DIR "XREAddonAppDir"
+
+/**
+ * A directory service key which provides the update directory. Callers should
+ * fall back to appDir.
+ * Windows:    If vendor name exists:
+ *             Documents and Settings\<User>\Local Settings\Application Data\
+ *             <vendor name>\updates\
+ *             <hash of the path to XRE_EXECUTABLE_FILE’s parent directory>
+ *
+ *             If vendor name doesn't exist, but product name exists:
+ *             Documents and Settings\<User>\Local Settings\Application Data\
+ *             <product name>\updates\
+ *             <hash of the path to XRE_EXECUTABLE_FILE’s parent directory>
+ *
+ *             If neither vendor nor product name exists:
+ *               If app dir is under Program Files:
+ *               Documents and Settings\<User>\Local Settings\Application Data\
+ *               <relative path to app dir from Program Files>
+ *
+ *               If app dir isn’t under Program Files:
+ *               Documents and Settings\<User>\Local Settings\Application Data\
+ *               <MOZ_APP_NAME>
+ *
+ * Mac:        ~/Library/Caches/Mozilla/updates/<absolute path to app dir>
+ *
+ * Gonk:       /data/local
+ *
+ * All others: Parent directory of XRE_EXECUTABLE_FILE.
+ */
+#define XRE_UPDATE_ROOT_DIR "UpdRootD"
+
+/**
+ * A directory service key which provides an alternate location
+ * to UpdRootD to  to store large files. This key is currently
+ * only implemented in the Gonk directory service provider.
+ */
+
+#define XRE_UPDATE_ARCHIVE_DIR "UpdArchD"
+
+/**
+ * A directory service key which provides the directory where an OS update is
+*  applied.
+ * At present this is supported only in Gonk.
+ */
+#define XRE_OS_UPDATE_APPLY_TO_DIR "OSUpdApplyToD"
+
+/**
+ * Begin an XUL application. Does not return until the user exits the
+ * application.
+ *
+ * @param argc/argv Command-line parameters to pass to the application. On
+ *                  Windows, these should be in UTF8. On unix-like platforms
+ *                  these are in the "native" character set.
+ *
+ * @param aAppData  Information about the application to be run.
+ *
+ * @param aFlags    Platform specific flags.
+ *
+ * @return         A native result code suitable for returning from main().
+ *
+ * @note           If the binary is linked against the standalone XPCOM glue,
+ *                 XPCOMGlueStartup() should be called before this method.
+ */
+XRE_API(int,
+        XRE_main, (int argc, char* argv[], const nsXREAppData* aAppData,
+                   uint32_t aFlags))
+
+/**
+ * Given a path relative to the current working directory (or an absolute
+ * path), return an appropriate nsIFile object.
+ *
+ * @note Pass UTF8 strings on Windows... native charset on other platforms.
+ */
+XRE_API(nsresult,
+        XRE_GetFileFromPath, (const char* aPath, nsIFile** aResult))
+
+/**
+ * Get the path of the running application binary and store it in aResult.
+ * @param aArgv0  The value passed as argv[0] of main(). This value is only
+ *                used on *nix, and only when other methods of determining
+ *                the binary path have failed.
+ */
+XRE_API(nsresult,
+        XRE_GetBinaryPath, (const char* aArgv0, nsIFile** aResult))
+
+/**
+ * Get the static module built in to libxul.
+ */
+XRE_API(const mozilla::Module*,
+        XRE_GetStaticModule, ())
+
+/**
+ * Lock a profile directory using platform-specific semantics.
+ *
+ * @param aDirectory  The profile directory to lock.
+ * @param aLockObject An opaque lock object. The directory will remain locked
+ *                    as long as the XPCOM reference is held.
+ */
+XRE_API(nsresult,
+        XRE_LockProfileDirectory, (nsIFile* aDirectory,
+                                   nsISupports** aLockObject))
+
+/**
+ * Initialize libXUL for embedding purposes.
+ *
+ * @param aLibXULDirectory   The directory in which the libXUL shared library
+ *                           was found.
+ * @param aAppDirectory      The directory in which the application components
+ *                           and resources can be found. This will map to
+ *                           the NS_OS_CURRENT_PROCESS_DIR directory service
+ *                           key.
+ * @param aAppDirProvider    A directory provider for the application. This
+ *                           provider will be aggregated by a libxul provider
+ *                           which will provide the base required GRE keys.
+ *
+ * @note This function must be called from the "main" thread.
+ *
+ * @note At the present time, this function may only be called once in
+ * a given process. Use XRE_TermEmbedding to clean up and free
+ * resources allocated by XRE_InitEmbedding.
+ */
+
+XRE_API(nsresult,
+        XRE_InitEmbedding2, (nsIFile* aLibXULDirectory,
+                             nsIFile* aAppDirectory,
+                             nsIDirectoryServiceProvider* aAppDirProvider))
+
+/**
+ * Register static XPCOM component information.
+ * This method may be called at any time before or after XRE_main or
+ * XRE_InitEmbedding.
+ */
+XRE_API(nsresult,
+        XRE_AddStaticComponent, (const mozilla::Module* aComponent))
+
+/**
+ * Register XPCOM components found in an array of files/directories.
+ * This method may be called at any time before or after XRE_main or
+ * XRE_InitEmbedding.
+ *
+ * @param aFiles An array of files or directories.
+ * @param aFileCount the number of items in the aFiles array.
+ * @note appdir/components is registered automatically.
+ *
+ * NS_APP_LOCATION specifies a location to search for binary XPCOM
+ * components as well as component/chrome manifest files.
+ *
+ * NS_EXTENSION_LOCATION excludes binary XPCOM components but allows other
+ * manifest instructions.
+ *
+ * NS_SKIN_LOCATION specifies a location to search for chrome manifest files
+ * which are only allowed to register only skin packages and style overlays.
+ */
+enum NSLocationType
+{
+  NS_APP_LOCATION,
+  NS_EXTENSION_LOCATION,
+  NS_SKIN_LOCATION,
+  NS_BOOTSTRAPPED_LOCATION
+};
+
+XRE_API(nsresult,
+        XRE_AddManifestLocation, (NSLocationType aType,
+                                  nsIFile* aLocation))
+
+/**
+ * Register XPCOM components found in a JAR.
+ * This is similar to XRE_AddManifestLocation except the file specified
+ * must be a zip archive with a manifest named chrome.manifest
+ * This method may be called at any time before or after XRE_main or
+ * XRE_InitEmbedding.
+ *
+ * @param aFiles An array of files or directories.
+ * @param aFileCount the number of items in the aFiles array.
+ * @note appdir/components is registered automatically.
+ *
+ * NS_COMPONENT_LOCATION specifies a location to search for binary XPCOM
+ * components as well as component/chrome manifest files.
+ *
+ * NS_SKIN_LOCATION specifies a location to search for chrome manifest files
+ * which are only allowed to register only skin packages and style overlays.
+ */
+XRE_API(nsresult,
+        XRE_AddJarManifestLocation, (NSLocationType aType,
+                                     nsIFile* aLocation))
+
+/**
+ * Fire notifications to inform the toolkit about a new profile. This
+ * method should be called after XRE_InitEmbedding if the embedder
+ * wishes to run with a profile. Normally the embedder should call
+ * XRE_LockProfileDirectory to lock the directory before calling this
+ * method.
+ *
+ * @note There are two possibilities for selecting a profile:
+ *
+ * 1) Select the profile before calling XRE_InitEmbedding. The aAppDirProvider
+ *    object passed to XRE_InitEmbedding should provide the
+ *    NS_APP_USER_PROFILE_50_DIR key, and may also provide the following keys:
+ *    - NS_APP_USER_PROFILE_LOCAL_50_DIR
+ *    - NS_APP_PROFILE_DIR_STARTUP
+ *    - NS_APP_PROFILE_LOCAL_DIR_STARTUP
+ *    In this scenario XRE_NotifyProfile should be called immediately after
+ *    XRE_InitEmbedding. Component registration information will be stored in
+ *    the profile and JS components may be stored in the fastload cache.
+ *
+ * 2) Select a profile some time after calling XRE_InitEmbedding. In this case
+ *    the embedder must install a directory service provider which provides
+ *    NS_APP_USER_PROFILE_50_DIR and optionally
+ *    NS_APP_USER_PROFILE_LOCAL_50_DIR. Component registration information
+ *    will be stored in the application directory and JS components will not
+ *    fastload.
+ */
+XRE_API(void,
+        XRE_NotifyProfile, ())
+
+/**
+ * Terminate embedding started with XRE_InitEmbedding or XRE_InitEmbedding2
+ */
+XRE_API(void,
+        XRE_TermEmbedding, ())
+
+/**
+ * Create a new nsXREAppData structure from an application.ini file.
+ *
+ * @param aINIFile The application.ini file to parse.
+ * @param aAppData A newly-allocated nsXREAppData structure. The caller is
+ *                 responsible for freeing this structure using
+ *                 XRE_FreeAppData.
+ */
+XRE_API(nsresult,
+        XRE_CreateAppData, (nsIFile* aINIFile,
+                            nsXREAppData** aAppData))
+
+/**
+ * Parse an INI file (application.ini or override.ini) into an existing
+ * nsXREAppData structure.
+ *
+ * @param aINIFile The INI file to parse
+ * @param aAppData The nsXREAppData structure to fill.
+ */
+XRE_API(nsresult,
+        XRE_ParseAppData, (nsIFile* aINIFile,
+                           nsXREAppData* aAppData))
+
+/**
+ * Free a nsXREAppData structure that was allocated with XRE_CreateAppData.
+ */
+XRE_API(void,
+        XRE_FreeAppData, (nsXREAppData* aAppData))
+
+enum GeckoProcessType
+{
+  GeckoProcessType_Default = 0,
+
+  GeckoProcessType_Plugin,
+  GeckoProcessType_Content,
+
+  GeckoProcessType_IPDLUnitTest,
+
+  GeckoProcessType_GMPlugin, // Gecko Media Plugin
+
+  GeckoProcessType_GPU,      // GPU and compositor process
+
+  GeckoProcessType_End,
+  GeckoProcessType_Invalid = GeckoProcessType_End
+};
+
+static const char* const kGeckoProcessTypeString[] = {
+  "default",
+  "plugin",
+  "tab",
+  "ipdlunittest",
+  "geckomediaplugin",
+  "gpu"
+};
+
+static_assert(MOZ_ARRAY_LENGTH(kGeckoProcessTypeString) ==
+              GeckoProcessType_End,
+              "Array length mismatch");
+
+XRE_API(const char*,
+        XRE_ChildProcessTypeToString, (GeckoProcessType aProcessType))
+
+XRE_API(void,
+        XRE_SetProcessType, (const char* aProcessTypeString))
+
+#if defined(MOZ_CRASHREPORTER)
+// Used in the "master" parent process hosting the crash server
+XRE_API(bool,
+        XRE_TakeMinidumpForChild, (uint32_t aChildPid, nsIFile** aDump,
+                                   uint32_t* aSequence))
+
+// Used in child processes.
+XRE_API(bool,
+        XRE_SetRemoteExceptionHandler, (const char* aPipe))
+#endif
+
+namespace mozilla {
+namespace gmp {
+class GMPLoader;
+} // namespace gmp
+} // namespace mozilla
+
+XRE_API(nsresult,
+        XRE_InitChildProcess, (int aArgc,
+                               char* aArgv[],
+                               const XREChildData* aChildData))
+
+XRE_API(GeckoProcessType,
+        XRE_GetProcessType, ())
+
+XRE_API(bool,
+        XRE_IsParentProcess, ())
+
+XRE_API(bool,
+        XRE_IsContentProcess, ())
+
+XRE_API(bool,
+        XRE_IsGPUProcess, ())
+
+typedef void (*MainFunction)(void* aData);
+
+XRE_API(nsresult,
+        XRE_InitParentProcess, (int aArgc,
+                                char* aArgv[],
+                                MainFunction aMainFunction,
+                                void* aMainFunctionExtraData))
+
+XRE_API(int,
+        XRE_RunIPDLTest, (int aArgc,
+                          char* aArgv[]))
+
+XRE_API(nsresult,
+        XRE_RunAppShell, ())
+
+XRE_API(nsresult,
+        XRE_InitCommandLine, (int aArgc, char* aArgv[]))
+
+XRE_API(nsresult,
+        XRE_DeinitCommandLine, ())
+
+class MessageLoop;
+
+XRE_API(void,
+        XRE_ShutdownChildProcess, ())
+
+XRE_API(MessageLoop*,
+        XRE_GetIOMessageLoop, ())
+
+XRE_API(bool,
+        XRE_SendTestShellCommand, (JSContext* aCx,
+                                   JSString* aCommand,
+                                   void* aCallback))
+XRE_API(bool,
+        XRE_ShutdownTestShell, ())
+
+XRE_API(void,
+        XRE_InstallX11ErrorHandler, ())
+
+XRE_API(void,
+        XRE_TelemetryAccumulate, (int aID, uint32_t aSample))
+
+XRE_API(void,
+        XRE_StartupTimelineRecord, (int aEvent, mozilla::TimeStamp aWhen))
+
+XRE_API(void,
+        XRE_InitOmnijar, (nsIFile* aGreOmni,
+                          nsIFile* aAppOmni))
+XRE_API(void,
+        XRE_StopLateWriteChecks, (void))
+
+XRE_API(void,
+        XRE_EnableSameExecutableForContentProc, ())
+
+XRE_API(int,
+        XRE_XPCShellMain, (int argc, char** argv, char** envp,
+                           const XREShellData* aShellData))
+
+#if MOZ_WIDGET_GTK == 2
+XRE_API(void,
+        XRE_GlibInit, ())
+#endif
+
+
+#ifdef LIBFUZZER
+#include "LibFuzzerRegistry.h"
+
+XRE_API(void,
+        XRE_LibFuzzerSetMain, (int, char**, LibFuzzerMain))
+
+XRE_API(void,
+        XRE_LibFuzzerGetFuncs, (const char*, LibFuzzerInitFunc*,
+                                LibFuzzerTestingFunc*))
+#endif // LIBFUZZER
+
+#endif // _nsXULAppAPI_h__
diff --git a/xpcom/build/perfprobe.cpp b/xpcom/build/perfprobe.cpp
new file mode 100644
index 000000000..118e73fc8
--- /dev/null
+++ b/xpcom/build/perfprobe.cpp
@@ -0,0 +1,242 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*****************************
+ Windows implementation of probes, using xperf
+ *****************************/
+#include <windows.h>
+#include <wmistr.h>
+#include <evntrace.h>
+
+#include "perfprobe.h"
+#include "nsAutoPtr.h"
+
+namespace mozilla {
+namespace probes {
+
+#if defined(MOZ_LOGGING)
+static LazyLogModule sProbeLog("SysProbe");
+#define LOG(x) MOZ_LOG(sProbeLog, mozilla::LogLevel::Debug, x)
+#else
+#define LOG(x)
+#endif
+
+// Utility function
+GUID
+CID_to_GUID(const nsCID& aCID)
+{
+  GUID result;
+  result.Data1 = aCID.m0;
+  result.Data2 = aCID.m1;
+  result.Data3 = aCID.m2;
+  for (int i = 0; i < 8; ++i) {
+    result.Data4[i] = aCID.m3[i];
+  }
+  return result;
+}
+
+
+// Implementation of Probe
+
+Probe::Probe(const nsCID& aGUID,
+             const nsACString& aName,
+             ProbeManager* aManager)
+  : mGUID(CID_to_GUID(aGUID))
+  , mName(aName)
+  , mManager(aManager)
+{
+}
+
+nsresult
+Probe::Trigger()
+{
+  if (!(mManager->mIsActive)) {
+    //Do not trigger if there is no session
+    return NS_OK;
+  }
+
+  _EVENT_TRACE_HEADER event;
+  ZeroMemory(&event, sizeof(event));
+  event.Size = sizeof(event);
+  event.Flags = WNODE_FLAG_TRACED_GUID ;
+  event.Guid = (const GUID)mGUID;
+  event.Class.Type    = 1;
+  event.Class.Version = 0;
+  event.Class.Level   = TRACE_LEVEL_INFORMATION;
+
+  ULONG result        = TraceEvent(mManager->mSessionHandle, &event);
+
+  LOG(("Probes: Triggered %s, %s, %ld",
+       mName.Data(),
+       result == ERROR_SUCCESS ? "success" : "failure",
+       result));
+
+  nsresult rv;
+  switch (result) {
+    case ERROR_SUCCESS:
+      rv = NS_OK;
+      break;
+    case ERROR_INVALID_FLAG_NUMBER:
+    case ERROR_MORE_DATA:
+    case ERROR_INVALID_PARAMETER:
+      rv = NS_ERROR_INVALID_ARG;
+      break;
+    case ERROR_INVALID_HANDLE:
+      rv = NS_ERROR_FAILURE;
+      break;
+    case ERROR_NOT_ENOUGH_MEMORY:
+    case ERROR_OUTOFMEMORY:
+      rv = NS_ERROR_OUT_OF_MEMORY;
+      break;
+    default:
+      rv = NS_ERROR_UNEXPECTED;
+  }
+  return rv;
+}
+
+
+// Implementation of ProbeManager
+
+ProbeManager::~ProbeManager()
+{
+  //If the manager goes out of scope, stop the session.
+  if (mIsActive && mRegistrationHandle) {
+    StopSession();
+  }
+}
+
+ProbeManager::ProbeManager(const nsCID& aApplicationUID,
+                           const nsACString& aApplicationName)
+  : mIsActive(false)
+  , mApplicationUID(aApplicationUID)
+  , mApplicationName(aApplicationName)
+  , mSessionHandle(0)
+  , mRegistrationHandle(0)
+  , mInitialized(false)
+{
+#if defined(MOZ_LOGGING)
+  char cidStr[NSID_LENGTH];
+  aApplicationUID.ToProvidedString(cidStr);
+  LOG(("ProbeManager::Init for application %s, %s",
+       aApplicationName.Data(), cidStr));
+#endif
+}
+
+//Note: The Windows API is just a little bit scary there.
+//The only way to obtain the session handle is to
+//- ignore the session handle obtained from RegisterTraceGuids
+//- pass a callback
+//- in that callback, request the session handle through
+//      GetTraceLoggerHandle and some opaque value received by the callback
+
+ULONG WINAPI
+ControlCallback(WMIDPREQUESTCODE aRequestCode,
+                PVOID aContext,
+                ULONG* aReserved,
+                PVOID aBuffer)
+{
+  ProbeManager* context = (ProbeManager*)aContext;
+  switch (aRequestCode) {
+    case WMI_ENABLE_EVENTS: {
+      context->mIsActive = true;
+      TRACEHANDLE sessionHandle = GetTraceLoggerHandle(aBuffer);
+      //Note: We only accept one handle
+      if ((HANDLE)sessionHandle == INVALID_HANDLE_VALUE) {
+        ULONG result = GetLastError();
+        LOG(("Probes: ControlCallback failed, %ul", result));
+        return result;
+      } else if (context->mIsActive && context->mSessionHandle &&
+                 context->mSessionHandle != sessionHandle) {
+        LOG(("Probes: Can only handle one context at a time, "
+             "ignoring activation"));
+        return ERROR_SUCCESS;
+      } else {
+        context->mSessionHandle = sessionHandle;
+        LOG(("Probes: ControlCallback activated"));
+        return ERROR_SUCCESS;
+      }
+    }
+
+    case WMI_DISABLE_EVENTS:
+      context->mIsActive      = false;
+      context->mSessionHandle = 0;
+      LOG(("Probes: ControlCallback deactivated"));
+      return ERROR_SUCCESS;
+
+    default:
+      LOG(("Probes: ControlCallback does not know what to do with %d",
+           aRequestCode));
+      return ERROR_INVALID_PARAMETER;
+  }
+}
+
+already_AddRefed<Probe>
+ProbeManager::GetProbe(const nsCID& aEventUID, const nsACString& aEventName)
+{
+  RefPtr<Probe> result(new Probe(aEventUID, aEventName, this));
+  mAllProbes.AppendElement(result);
+  return result.forget();
+}
+
+nsresult
+ProbeManager::StartSession()
+{
+  return StartSession(mAllProbes);
+}
+
+nsresult
+ProbeManager::StartSession(nsTArray<RefPtr<Probe>>& aProbes)
+{
+  const size_t probesCount = aProbes.Length();
+  _TRACE_GUID_REGISTRATION* probes = new _TRACE_GUID_REGISTRATION[probesCount];
+  for (unsigned int i = 0; i < probesCount; ++i) {
+    const Probe* probe = aProbes[i];
+    const Probe* probeX = static_cast<const Probe*>(probe);
+    probes[i].Guid = (LPCGUID)&probeX->mGUID;
+  }
+  ULONG result =
+    RegisterTraceGuids(&ControlCallback
+                       /*RequestAddress: Sets mSessions appropriately.*/,
+                       this
+                       /*RequestContext: Passed to ControlCallback*/,
+                       (LPGUID)&mApplicationUID
+                       /*ControlGuid:    Tracing GUID
+                        the cast comes from MSDN examples*/,
+                       probesCount
+                       /*GuidCount:      Number of probes*/,
+                       probes
+                       /*TraceGuidReg:   Probes registration*/,
+                       nullptr
+                       /*MofImagePath:   Must be nullptr, says MSDN*/,
+                       nullptr
+                       /*MofResourceName:Must be nullptr, says MSDN*/,
+                       &mRegistrationHandle
+                       /*RegistrationHandle: Handler.
+                        used only for unregistration*/
+                      );
+  delete[] probes;
+  if (NS_WARN_IF(result != ERROR_SUCCESS)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return NS_OK;
+}
+
+nsresult
+ProbeManager::StopSession()
+{
+  LOG(("Probes: Stopping measures"));
+  if (mSessionHandle != 0) {
+    ULONG result = UnregisterTraceGuids(mSessionHandle);
+    mSessionHandle = 0;
+    if (result != ERROR_SUCCESS) {
+      return NS_ERROR_INVALID_ARG;
+    }
+  }
+  return NS_OK;
+}
+
+} // namespace probes
+} // namespace mozilla
diff --git a/xpcom/build/perfprobe.h b/xpcom/build/perfprobe.h
new file mode 100644
index 000000000..bc3563654
--- /dev/null
+++ b/xpcom/build/perfprobe.h
@@ -0,0 +1,204 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * A mechanism for interacting with operating system-provided
+ * debugging/profiling tools such as Microsoft EWT/Windows Performance Toolkit.
+ */
+
+#ifndef mozilla_perfprobe_h
+#define mozilla_perfprobe_h
+
+#if !defined(XP_WIN)
+#error "For the moment, perfprobe.h is defined only for Windows platforms"
+#endif
+
+#include "nsError.h"
+#include "nsString.h"
+#include "mozilla/Logging.h"
+#include "nsTArray.h"
+#include "nsAutoPtr.h"
+#include <windows.h>
+#undef GetStartupInfo //Prevent Windows from polluting global namespace
+#include <wmistr.h>
+#include <evntrace.h>
+
+namespace mozilla {
+namespace probes {
+
+class ProbeManager;
+
+/**
+ * A data structure supporting a trigger operation that can be used to
+ * send information to the operating system.
+ */
+
+class Probe
+{
+public:
+  NS_INLINE_DECL_REFCOUNTING(Probe)
+
+  /**
+   * Trigger the event.
+   *
+   * Note: Can be called from any thread.
+   */
+  nsresult Trigger();
+
+protected:
+  ~Probe() {};
+
+  Probe(const nsCID& aGUID, const nsACString& aName, ProbeManager* aManager);
+  friend class ProbeManager;
+
+protected:
+
+  /**
+   * The system GUID associated to this probe. See the documentation
+   * of |ProbeManager::Make| for more details.
+   */
+  const GUID mGUID;
+
+  /**
+   * The name of this probe. See the documentation
+   * of |ProbeManager::Make| for more details.
+   */
+  const nsCString mName;
+
+  /**
+   * The ProbeManager managing this probe.
+   *
+   * Note: This is a weak reference to avoid a useless cycle.
+   */
+  class ProbeManager* mManager;
+};
+
+
+/**
+ * A manager for a group of probes.
+ *
+ * You can have several managers in one application, provided that they all
+ * have distinct IDs and names. However, having more than 2 is considered a bad
+ * practice.
+ */
+class ProbeManager
+{
+public:
+  NS_INLINE_DECL_REFCOUNTING(ProbeManager)
+
+  /**
+   * Create a new probe manager.
+   *
+   * This constructor should be called from the main thread.
+   *
+   * @param aApplicationUID The unique ID of the probe. Under Windows, this
+   * unique ID must have been previously registered using an external tool.
+   * See MyCategory on http://msdn.microsoft.com/en-us/library/aa364100.aspx
+   * @param aApplicationName A name for the probe. Currently used only for
+   * logging purposes. In the future, may be attached to the data sent to the
+   * operating system.
+   *
+   * Note: If two ProbeManagers are constructed with the same uid and/or name,
+   * behavior is unspecified.
+   */
+  ProbeManager(const nsCID& aApplicationUID,
+               const nsACString& aApplicationName);
+
+  /**
+   * Acquire a probe.
+   *
+   * Note: Only probes acquired before the call to SetReady are taken into
+   * account
+   * Note: Can be called only from the main thread.
+   *
+   * @param aEventUID The unique ID of the probe. Under Windows, this unique
+   * ID must have been previously registered using an external tool.
+   * See MyCategory on http://msdn.microsoft.com/en-us/library/aa364100.aspx
+   * @param aEventName A name for the probe. Currently used only for logging
+   * purposes. In the
+   * future, may be attached to the data sent to the operating system.
+   * @return Either |null| in case of error or a valid |Probe*|.
+   *
+   * Note: If this method is called twice with the same uid and/or name,
+   * behavior is undefined.
+   */
+  already_AddRefed<Probe> GetProbe(const nsCID& aEventUID,
+                                   const nsACString& aEventName);
+
+  /**
+   * Start/stop the measuring session.
+   *
+   * This method should be called from the main thread.
+   *
+   * Note that starting an already started probe manager has no effect,
+   * nor does stopping an already stopped probe manager.
+   */
+  nsresult StartSession();
+  nsresult StopSession();
+
+  /**
+   * @return true If measures are currently on, i.e. if triggering probes is any
+   * is useful. You do not have to check this before triggering a probe, unless
+   * this can avoid complex computations.
+   */
+  bool IsActive();
+
+protected:
+  ~ProbeManager();
+
+  nsresult StartSession(nsTArray<RefPtr<Probe>>& aProbes);
+  nsresult Init(const nsCID& aApplicationUID,
+                const nsACString& aApplicationName);
+
+protected:
+  /**
+   * `true` if a session is in activity, `false` otherwise.
+   */
+  bool mIsActive;
+
+  /**
+   * The UID of this manager.
+   * See documentation above for registration steps that you
+   * may have to take.
+   */
+  nsCID mApplicationUID;
+
+  /**
+   * The name of the application.
+   */
+  nsCString mApplicationName;
+
+  /**
+   * All the probes that have been created for this manager.
+   */
+  nsTArray<RefPtr<Probe>> mAllProbes;
+
+  /**
+   * Handle used for triggering events
+   */
+  TRACEHANDLE mSessionHandle;
+
+  /**
+   * Handle used for registration/unregistration
+   */
+  TRACEHANDLE mRegistrationHandle;
+
+  /**
+   * `true` if initialization has been performed, `false` until then.
+   */
+  bool mInitialized;
+
+  friend class Probe;  // Needs to access |mSessionHandle|
+  friend ULONG WINAPI ControlCallback(WMIDPREQUESTCODE aRequestCode,
+                                      PVOID aContext,
+                                      ULONG* aReserved,
+                                      PVOID aBuffer);  // Sets |mSessionHandle|
+};
+
+} // namespace probes
+} // namespace mozilla
+
+#endif //mozilla_perfprobe_h
diff --git a/xpcom/build/xpcom_alpha.def b/xpcom/build/xpcom_alpha.def
new file mode 100644
index 000000000..38fedfa17
--- /dev/null
+++ b/xpcom/build/xpcom_alpha.def
@@ -0,0 +1,256 @@
+;+# This Source Code Form is subject to the terms of the Mozilla Public
+;+# License, v. 2.0. If a copy of the MPL was not distributed with this
+;+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+LIBRARY xpcom
+DESCRIPTION "xpcom library"
+
+EXPORTS
+    ?Stub3@nsXPTCStubBase@@UAAIXZ
+    ?Stub4@nsXPTCStubBase@@UAAIXZ
+    ?Stub5@nsXPTCStubBase@@UAAIXZ
+    ?Stub6@nsXPTCStubBase@@UAAIXZ
+    ?Stub7@nsXPTCStubBase@@UAAIXZ
+    ?Stub8@nsXPTCStubBase@@UAAIXZ
+    ?Stub9@nsXPTCStubBase@@UAAIXZ
+    ?Stub10@nsXPTCStubBase@@UAAIXZ
+    ?Stub11@nsXPTCStubBase@@UAAIXZ
+    ?Stub12@nsXPTCStubBase@@UAAIXZ
+    ?Stub13@nsXPTCStubBase@@UAAIXZ
+    ?Stub14@nsXPTCStubBase@@UAAIXZ
+    ?Stub15@nsXPTCStubBase@@UAAIXZ
+    ?Stub16@nsXPTCStubBase@@UAAIXZ
+    ?Stub17@nsXPTCStubBase@@UAAIXZ
+    ?Stub18@nsXPTCStubBase@@UAAIXZ
+    ?Stub19@nsXPTCStubBase@@UAAIXZ
+    ?Stub20@nsXPTCStubBase@@UAAIXZ
+    ?Stub21@nsXPTCStubBase@@UAAIXZ
+    ?Stub22@nsXPTCStubBase@@UAAIXZ
+    ?Stub23@nsXPTCStubBase@@UAAIXZ
+    ?Stub24@nsXPTCStubBase@@UAAIXZ
+    ?Stub25@nsXPTCStubBase@@UAAIXZ
+    ?Stub26@nsXPTCStubBase@@UAAIXZ
+    ?Stub27@nsXPTCStubBase@@UAAIXZ
+    ?Stub28@nsXPTCStubBase@@UAAIXZ
+    ?Stub29@nsXPTCStubBase@@UAAIXZ
+    ?Stub30@nsXPTCStubBase@@UAAIXZ
+    ?Stub31@nsXPTCStubBase@@UAAIXZ
+    ?Stub32@nsXPTCStubBase@@UAAIXZ
+    ?Stub33@nsXPTCStubBase@@UAAIXZ
+    ?Stub34@nsXPTCStubBase@@UAAIXZ
+    ?Stub35@nsXPTCStubBase@@UAAIXZ
+    ?Stub36@nsXPTCStubBase@@UAAIXZ
+    ?Stub37@nsXPTCStubBase@@UAAIXZ
+    ?Stub38@nsXPTCStubBase@@UAAIXZ
+    ?Stub39@nsXPTCStubBase@@UAAIXZ
+    ?Stub40@nsXPTCStubBase@@UAAIXZ
+    ?Stub41@nsXPTCStubBase@@UAAIXZ
+    ?Stub42@nsXPTCStubBase@@UAAIXZ
+    ?Stub43@nsXPTCStubBase@@UAAIXZ
+    ?Stub44@nsXPTCStubBase@@UAAIXZ
+    ?Stub45@nsXPTCStubBase@@UAAIXZ
+    ?Stub46@nsXPTCStubBase@@UAAIXZ
+    ?Stub47@nsXPTCStubBase@@UAAIXZ
+    ?Stub48@nsXPTCStubBase@@UAAIXZ
+    ?Stub49@nsXPTCStubBase@@UAAIXZ
+    ?Stub50@nsXPTCStubBase@@UAAIXZ
+    ?Stub51@nsXPTCStubBase@@UAAIXZ
+    ?Stub52@nsXPTCStubBase@@UAAIXZ
+    ?Stub53@nsXPTCStubBase@@UAAIXZ
+    ?Stub54@nsXPTCStubBase@@UAAIXZ
+    ?Stub55@nsXPTCStubBase@@UAAIXZ
+    ?Stub56@nsXPTCStubBase@@UAAIXZ
+    ?Stub57@nsXPTCStubBase@@UAAIXZ
+    ?Stub58@nsXPTCStubBase@@UAAIXZ
+    ?Stub59@nsXPTCStubBase@@UAAIXZ
+    ?Stub60@nsXPTCStubBase@@UAAIXZ
+    ?Stub61@nsXPTCStubBase@@UAAIXZ
+    ?Stub62@nsXPTCStubBase@@UAAIXZ
+    ?Stub63@nsXPTCStubBase@@UAAIXZ
+    ?Stub64@nsXPTCStubBase@@UAAIXZ
+    ?Stub65@nsXPTCStubBase@@UAAIXZ
+    ?Stub66@nsXPTCStubBase@@UAAIXZ
+    ?Stub67@nsXPTCStubBase@@UAAIXZ
+    ?Stub68@nsXPTCStubBase@@UAAIXZ
+    ?Stub69@nsXPTCStubBase@@UAAIXZ
+    ?Stub70@nsXPTCStubBase@@UAAIXZ
+    ?Stub71@nsXPTCStubBase@@UAAIXZ
+    ?Stub72@nsXPTCStubBase@@UAAIXZ
+    ?Stub73@nsXPTCStubBase@@UAAIXZ
+    ?Stub74@nsXPTCStubBase@@UAAIXZ
+    ?Stub75@nsXPTCStubBase@@UAAIXZ
+    ?Stub76@nsXPTCStubBase@@UAAIXZ
+    ?Stub77@nsXPTCStubBase@@UAAIXZ
+    ?Stub78@nsXPTCStubBase@@UAAIXZ
+    ?Stub79@nsXPTCStubBase@@UAAIXZ
+    ?Stub80@nsXPTCStubBase@@UAAIXZ
+    ?Stub81@nsXPTCStubBase@@UAAIXZ
+    ?Stub82@nsXPTCStubBase@@UAAIXZ
+    ?Stub83@nsXPTCStubBase@@UAAIXZ
+    ?Stub84@nsXPTCStubBase@@UAAIXZ
+    ?Stub85@nsXPTCStubBase@@UAAIXZ
+    ?Stub86@nsXPTCStubBase@@UAAIXZ
+    ?Stub87@nsXPTCStubBase@@UAAIXZ
+    ?Stub88@nsXPTCStubBase@@UAAIXZ
+    ?Stub89@nsXPTCStubBase@@UAAIXZ
+    ?Stub90@nsXPTCStubBase@@UAAIXZ
+    ?Stub91@nsXPTCStubBase@@UAAIXZ
+    ?Stub92@nsXPTCStubBase@@UAAIXZ
+    ?Stub93@nsXPTCStubBase@@UAAIXZ
+    ?Stub94@nsXPTCStubBase@@UAAIXZ
+    ?Stub95@nsXPTCStubBase@@UAAIXZ
+    ?Stub96@nsXPTCStubBase@@UAAIXZ
+    ?Stub97@nsXPTCStubBase@@UAAIXZ
+    ?Stub98@nsXPTCStubBase@@UAAIXZ
+    ?Stub99@nsXPTCStubBase@@UAAIXZ
+    ?Stub100@nsXPTCStubBase@@UAAIXZ
+    ?Stub101@nsXPTCStubBase@@UAAIXZ
+    ?Stub102@nsXPTCStubBase@@UAAIXZ
+    ?Stub103@nsXPTCStubBase@@UAAIXZ
+    ?Stub104@nsXPTCStubBase@@UAAIXZ
+    ?Stub105@nsXPTCStubBase@@UAAIXZ
+    ?Stub106@nsXPTCStubBase@@UAAIXZ
+    ?Stub107@nsXPTCStubBase@@UAAIXZ
+    ?Stub108@nsXPTCStubBase@@UAAIXZ
+    ?Stub109@nsXPTCStubBase@@UAAIXZ
+    ?Stub110@nsXPTCStubBase@@UAAIXZ
+    ?Stub111@nsXPTCStubBase@@UAAIXZ
+    ?Stub112@nsXPTCStubBase@@UAAIXZ
+    ?Stub113@nsXPTCStubBase@@UAAIXZ
+    ?Stub114@nsXPTCStubBase@@UAAIXZ
+    ?Stub115@nsXPTCStubBase@@UAAIXZ
+    ?Stub116@nsXPTCStubBase@@UAAIXZ
+    ?Stub117@nsXPTCStubBase@@UAAIXZ
+    ?Stub118@nsXPTCStubBase@@UAAIXZ
+    ?Stub119@nsXPTCStubBase@@UAAIXZ
+    ?Stub120@nsXPTCStubBase@@UAAIXZ
+    ?Stub121@nsXPTCStubBase@@UAAIXZ
+    ?Stub122@nsXPTCStubBase@@UAAIXZ
+    ?Stub123@nsXPTCStubBase@@UAAIXZ
+    ?Stub124@nsXPTCStubBase@@UAAIXZ
+    ?Stub125@nsXPTCStubBase@@UAAIXZ
+    ?Stub126@nsXPTCStubBase@@UAAIXZ
+    ?Stub127@nsXPTCStubBase@@UAAIXZ
+    ?Stub128@nsXPTCStubBase@@UAAIXZ
+    ?Stub129@nsXPTCStubBase@@UAAIXZ
+    ?Stub130@nsXPTCStubBase@@UAAIXZ
+    ?Stub131@nsXPTCStubBase@@UAAIXZ
+    ?Stub132@nsXPTCStubBase@@UAAIXZ
+    ?Stub133@nsXPTCStubBase@@UAAIXZ
+    ?Stub134@nsXPTCStubBase@@UAAIXZ
+    ?Stub135@nsXPTCStubBase@@UAAIXZ
+    ?Stub136@nsXPTCStubBase@@UAAIXZ
+    ?Stub137@nsXPTCStubBase@@UAAIXZ
+    ?Stub138@nsXPTCStubBase@@UAAIXZ
+    ?Stub139@nsXPTCStubBase@@UAAIXZ
+    ?Stub140@nsXPTCStubBase@@UAAIXZ
+    ?Stub141@nsXPTCStubBase@@UAAIXZ
+    ?Stub142@nsXPTCStubBase@@UAAIXZ
+    ?Stub143@nsXPTCStubBase@@UAAIXZ
+    ?Stub144@nsXPTCStubBase@@UAAIXZ
+    ?Stub145@nsXPTCStubBase@@UAAIXZ
+    ?Stub146@nsXPTCStubBase@@UAAIXZ
+    ?Stub147@nsXPTCStubBase@@UAAIXZ
+    ?Stub148@nsXPTCStubBase@@UAAIXZ
+    ?Stub149@nsXPTCStubBase@@UAAIXZ
+    ?Stub150@nsXPTCStubBase@@UAAIXZ
+    ?Stub151@nsXPTCStubBase@@UAAIXZ
+    ?Stub152@nsXPTCStubBase@@UAAIXZ
+    ?Stub153@nsXPTCStubBase@@UAAIXZ
+    ?Stub154@nsXPTCStubBase@@UAAIXZ
+    ?Stub155@nsXPTCStubBase@@UAAIXZ
+    ?Stub156@nsXPTCStubBase@@UAAIXZ
+    ?Stub157@nsXPTCStubBase@@UAAIXZ
+    ?Stub158@nsXPTCStubBase@@UAAIXZ
+    ?Stub159@nsXPTCStubBase@@UAAIXZ
+    ?Stub160@nsXPTCStubBase@@UAAIXZ
+    ?Stub161@nsXPTCStubBase@@UAAIXZ
+    ?Stub162@nsXPTCStubBase@@UAAIXZ
+    ?Stub163@nsXPTCStubBase@@UAAIXZ
+    ?Stub164@nsXPTCStubBase@@UAAIXZ
+    ?Stub165@nsXPTCStubBase@@UAAIXZ
+    ?Stub166@nsXPTCStubBase@@UAAIXZ
+    ?Stub167@nsXPTCStubBase@@UAAIXZ
+    ?Stub168@nsXPTCStubBase@@UAAIXZ
+    ?Stub169@nsXPTCStubBase@@UAAIXZ
+    ?Stub170@nsXPTCStubBase@@UAAIXZ
+    ?Stub171@nsXPTCStubBase@@UAAIXZ
+    ?Stub172@nsXPTCStubBase@@UAAIXZ
+    ?Stub173@nsXPTCStubBase@@UAAIXZ
+    ?Stub174@nsXPTCStubBase@@UAAIXZ
+    ?Stub175@nsXPTCStubBase@@UAAIXZ
+    ?Stub176@nsXPTCStubBase@@UAAIXZ
+    ?Stub177@nsXPTCStubBase@@UAAIXZ
+    ?Stub178@nsXPTCStubBase@@UAAIXZ
+    ?Stub179@nsXPTCStubBase@@UAAIXZ
+    ?Stub180@nsXPTCStubBase@@UAAIXZ
+    ?Stub181@nsXPTCStubBase@@UAAIXZ
+    ?Stub182@nsXPTCStubBase@@UAAIXZ
+    ?Stub183@nsXPTCStubBase@@UAAIXZ
+    ?Stub184@nsXPTCStubBase@@UAAIXZ
+    ?Stub185@nsXPTCStubBase@@UAAIXZ
+    ?Stub186@nsXPTCStubBase@@UAAIXZ
+    ?Stub187@nsXPTCStubBase@@UAAIXZ
+    ?Stub188@nsXPTCStubBase@@UAAIXZ
+    ?Stub189@nsXPTCStubBase@@UAAIXZ
+    ?Stub190@nsXPTCStubBase@@UAAIXZ
+    ?Stub191@nsXPTCStubBase@@UAAIXZ
+    ?Stub192@nsXPTCStubBase@@UAAIXZ
+    ?Stub193@nsXPTCStubBase@@UAAIXZ
+    ?Stub194@nsXPTCStubBase@@UAAIXZ
+    ?Stub195@nsXPTCStubBase@@UAAIXZ
+    ?Stub196@nsXPTCStubBase@@UAAIXZ
+    ?Stub197@nsXPTCStubBase@@UAAIXZ
+    ?Stub198@nsXPTCStubBase@@UAAIXZ
+    ?Stub199@nsXPTCStubBase@@UAAIXZ
+    ?Stub200@nsXPTCStubBase@@UAAIXZ
+    ?Stub201@nsXPTCStubBase@@UAAIXZ
+    ?Stub202@nsXPTCStubBase@@UAAIXZ
+    ?Stub203@nsXPTCStubBase@@UAAIXZ
+    ?Stub204@nsXPTCStubBase@@UAAIXZ
+    ?Stub205@nsXPTCStubBase@@UAAIXZ
+    ?Stub206@nsXPTCStubBase@@UAAIXZ
+    ?Stub207@nsXPTCStubBase@@UAAIXZ
+    ?Stub208@nsXPTCStubBase@@UAAIXZ
+    ?Stub209@nsXPTCStubBase@@UAAIXZ
+    ?Stub210@nsXPTCStubBase@@UAAIXZ
+    ?Stub211@nsXPTCStubBase@@UAAIXZ
+    ?Stub212@nsXPTCStubBase@@UAAIXZ
+    ?Stub213@nsXPTCStubBase@@UAAIXZ
+    ?Stub214@nsXPTCStubBase@@UAAIXZ
+    ?Stub215@nsXPTCStubBase@@UAAIXZ
+    ?Stub216@nsXPTCStubBase@@UAAIXZ
+    ?Stub217@nsXPTCStubBase@@UAAIXZ
+    ?Stub218@nsXPTCStubBase@@UAAIXZ
+    ?Stub219@nsXPTCStubBase@@UAAIXZ
+    ?Stub220@nsXPTCStubBase@@UAAIXZ
+    ?Stub221@nsXPTCStubBase@@UAAIXZ
+    ?Stub222@nsXPTCStubBase@@UAAIXZ
+    ?Stub223@nsXPTCStubBase@@UAAIXZ
+    ?Stub224@nsXPTCStubBase@@UAAIXZ
+    ?Stub225@nsXPTCStubBase@@UAAIXZ
+    ?Stub226@nsXPTCStubBase@@UAAIXZ
+    ?Stub227@nsXPTCStubBase@@UAAIXZ
+    ?Stub228@nsXPTCStubBase@@UAAIXZ
+    ?Stub229@nsXPTCStubBase@@UAAIXZ
+    ?Stub230@nsXPTCStubBase@@UAAIXZ
+    ?Stub231@nsXPTCStubBase@@UAAIXZ
+    ?Stub232@nsXPTCStubBase@@UAAIXZ
+    ?Stub233@nsXPTCStubBase@@UAAIXZ
+    ?Stub234@nsXPTCStubBase@@UAAIXZ
+    ?Stub235@nsXPTCStubBase@@UAAIXZ
+    ?Stub236@nsXPTCStubBase@@UAAIXZ
+    ?Stub237@nsXPTCStubBase@@UAAIXZ
+    ?Stub238@nsXPTCStubBase@@UAAIXZ
+    ?Stub239@nsXPTCStubBase@@UAAIXZ
+    ?Stub240@nsXPTCStubBase@@UAAIXZ
+    ?Stub241@nsXPTCStubBase@@UAAIXZ
+    ?Stub242@nsXPTCStubBase@@UAAIXZ
+    ?Stub243@nsXPTCStubBase@@UAAIXZ
+    ?Stub244@nsXPTCStubBase@@UAAIXZ
+    ?Stub245@nsXPTCStubBase@@UAAIXZ
+    ?Stub246@nsXPTCStubBase@@UAAIXZ
+    ?Stub247@nsXPTCStubBase@@UAAIXZ
+    ?Stub248@nsXPTCStubBase@@UAAIXZ
+    ?Stub249@nsXPTCStubBase@@UAAIXZ
+
diff --git a/xpcom/build/xrecore.h b/xpcom/build/xrecore.h
new file mode 100644
index 000000000..9749a8e90
--- /dev/null
+++ b/xpcom/build/xrecore.h
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef xrecore_h__
+#define xrecore_h__
+
+#include "nscore.h"
+
+/**
+ * Import/export macros for libXUL APIs.
+ */
+#ifdef XPCOM_GLUE
+#define XRE_API(type, name, params) \
+  typedef type (NS_FROZENCALL * name##Type) params; \
+  extern name##Type name NS_HIDDEN;
+#elif defined(IMPL_LIBXUL)
+#define XRE_API(type, name, params) EXPORT_XPCOM_API(type) name params;
+#else
+#define XRE_API(type, name, params) IMPORT_XPCOM_API(type) name params;
+#endif
+
+#endif // xrecore_h__
diff --git a/xpcom/components/ManifestParser.cpp b/xpcom/components/ManifestParser.cpp
new file mode 100644
index 000000000..4dcfc8402
--- /dev/null
+++ b/xpcom/components/ManifestParser.cpp
@@ -0,0 +1,792 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ArrayUtils.h"
+
+#include "ManifestParser.h"
+
+#include <string.h>
+
+#include "prio.h"
+#include "prprf.h"
+#if defined(XP_WIN)
+#include <windows.h>
+#elif defined(MOZ_WIDGET_COCOA)
+#include <CoreServices/CoreServices.h>
+#include "nsCocoaFeatures.h"
+#elif defined(MOZ_WIDGET_GTK)
+#include <gtk/gtk.h>
+#endif
+
+#ifdef MOZ_WIDGET_ANDROID
+#include "AndroidBridge.h"
+#endif
+
+#include "mozilla/Services.h"
+
+#include "nsCRT.h"
+#include "nsConsoleMessage.h"
+#include "nsTextFormatter.h"
+#include "nsVersionComparator.h"
+#include "nsXPCOMCIDInternal.h"
+
+#include "nsIConsoleService.h"
+#include "nsIScriptError.h"
+#include "nsIXULAppInfo.h"
+#include "nsIXULRuntime.h"
+
+using namespace mozilla;
+
+struct ManifestDirective
+{
+  const char* directive;
+  int argc;
+
+  // Binary components are only allowed for APP locations.
+  bool apponly;
+
+  // Some directives should only be delivered for APP or EXTENSION locations.
+  bool componentonly;
+
+  bool ischrome;
+
+  bool allowbootstrap;
+
+  // The platform/contentaccessible flags only apply to content directives.
+  bool contentflags;
+
+  // Function to handle this directive. This isn't a union because C++ still
+  // hasn't learned how to initialize unions in a sane way.
+  void (nsComponentManagerImpl::*mgrfunc)(
+    nsComponentManagerImpl::ManifestProcessingContext& aCx,
+    int aLineNo, char* const* aArgv);
+  void (nsChromeRegistry::*regfunc)(
+    nsChromeRegistry::ManifestProcessingContext& aCx,
+    int aLineNo, char* const* aArgv, int aFlags);
+  void* xptonlyfunc;
+
+  bool isContract;
+};
+static const ManifestDirective kParsingTable[] = {
+  {
+    "manifest",         1, false, false, true, true, false,
+    &nsComponentManagerImpl::ManifestManifest, nullptr, nullptr
+  },
+  {
+    "binary-component", 1, true, true, false, false, false,
+    &nsComponentManagerImpl::ManifestBinaryComponent, nullptr, nullptr
+  },
+  {
+    "interfaces",       1, false, true, false, false, false,
+    &nsComponentManagerImpl::ManifestXPT, nullptr, nullptr
+  },
+  {
+    "component",        2, false, true, false, false, false,
+    &nsComponentManagerImpl::ManifestComponent, nullptr, nullptr
+  },
+  {
+    "contract",         2, false, true, false, false, false,
+    &nsComponentManagerImpl::ManifestContract, nullptr, nullptr, true
+  },
+  {
+    "category",         3, false, true, false, false, false,
+    &nsComponentManagerImpl::ManifestCategory, nullptr, nullptr
+  },
+  {
+    "content",          2, false, true, true, true,  true,
+    nullptr, &nsChromeRegistry::ManifestContent, nullptr
+  },
+  {
+    "locale",           3, false, true, true, true, false,
+    nullptr, &nsChromeRegistry::ManifestLocale, nullptr
+  },
+  {
+    "skin",             3, false, false, true, true, false,
+    nullptr, &nsChromeRegistry::ManifestSkin, nullptr
+  },
+  {
+    "overlay",          2, false, true, true, false, false,
+    nullptr, &nsChromeRegistry::ManifestOverlay, nullptr
+  },
+  {
+    "style",            2, false, false, true, false, false,
+    nullptr, &nsChromeRegistry::ManifestStyle, nullptr
+  },
+  {
+    // NB: note that while skin manifests can use this, they are only allowed
+    // to use it for chrome://../skin/ URLs
+    "override",         2, false, false, true, true, false,
+    nullptr, &nsChromeRegistry::ManifestOverride, nullptr
+  },
+  {
+    "resource",         2, false, true, true, true, false,
+    nullptr, &nsChromeRegistry::ManifestResource, nullptr
+  }
+};
+
+static const char kWhitespace[] = "\t ";
+
+static bool
+IsNewline(char aChar)
+{
+  return aChar == '\n' || aChar == '\r';
+}
+
+namespace {
+struct AutoPR_smprintf_free
+{
+  explicit AutoPR_smprintf_free(char* aBuf) : mBuf(aBuf) {}
+
+  ~AutoPR_smprintf_free()
+  {
+    if (mBuf) {
+      PR_smprintf_free(mBuf);
+    }
+  }
+
+  operator char*() const { return mBuf; }
+
+  char* mBuf;
+};
+
+} // namespace
+
+/**
+ * If we are pre-loading XPTs, this method may do nothing because the
+ * console service is not initialized.
+ */
+void
+LogMessage(const char* aMsg, ...)
+{
+  if (!nsComponentManagerImpl::gComponentManager) {
+    return;
+  }
+
+  nsCOMPtr<nsIConsoleService> console =
+    do_GetService(NS_CONSOLESERVICE_CONTRACTID);
+  if (!console) {
+    return;
+  }
+
+  va_list args;
+  va_start(args, aMsg);
+  AutoPR_smprintf_free formatted(PR_vsmprintf(aMsg, args));
+  va_end(args);
+
+  nsCOMPtr<nsIConsoleMessage> error =
+    new nsConsoleMessage(NS_ConvertUTF8toUTF16(formatted).get());
+  console->LogMessage(error);
+}
+
+/**
+ * If we are pre-loading XPTs, this method may do nothing because the
+ * console service is not initialized.
+ */
+void
+LogMessageWithContext(FileLocation& aFile,
+                      uint32_t aLineNumber, const char* aMsg, ...)
+{
+  va_list args;
+  va_start(args, aMsg);
+  AutoPR_smprintf_free formatted(PR_vsmprintf(aMsg, args));
+  va_end(args);
+  if (!formatted) {
+    return;
+  }
+
+  if (!nsComponentManagerImpl::gComponentManager) {
+    return;
+  }
+
+  nsCString file;
+  aFile.GetURIString(file);
+
+  nsCOMPtr<nsIScriptError> error =
+    do_CreateInstance(NS_SCRIPTERROR_CONTRACTID);
+  if (!error) {
+    // This can happen early in component registration. Fall back to a
+    // generic console message.
+    LogMessage("Warning: in '%s', line %i: %s", file.get(),
+               aLineNumber, (char*)formatted);
+    return;
+  }
+
+  nsCOMPtr<nsIConsoleService> console =
+    do_GetService(NS_CONSOLESERVICE_CONTRACTID);
+  if (!console) {
+    return;
+  }
+
+  nsresult rv = error->Init(NS_ConvertUTF8toUTF16(formatted),
+                            NS_ConvertUTF8toUTF16(file), EmptyString(),
+                            aLineNumber, 0, nsIScriptError::warningFlag,
+                            "chrome registration");
+  if (NS_FAILED(rv)) {
+    return;
+  }
+
+  console->LogMessage(error);
+}
+
+/**
+ * Check for a modifier flag of the following forms:
+ *   "flag"   (same as "true")
+ *   "flag=yes|true|1"
+ *   "flag="no|false|0"
+ * @param aFlag The flag to compare.
+ * @param aData The tokenized data to check; this is lowercased
+ *              before being passed in.
+ * @param aResult If the flag is found, the value is assigned here.
+ * @return Whether the flag was handled.
+ */
+static bool
+CheckFlag(const nsSubstring& aFlag, const nsSubstring& aData, bool& aResult)
+{
+  if (!StringBeginsWith(aData, aFlag)) {
+    return false;
+  }
+
+  if (aFlag.Length() == aData.Length()) {
+    // the data is simply "flag", which is the same as "flag=yes"
+    aResult = true;
+    return true;
+  }
+
+  if (aData.CharAt(aFlag.Length()) != '=') {
+    // the data is "flag2=", which is not anything we care about
+    return false;
+  }
+
+  if (aData.Length() == aFlag.Length() + 1) {
+    aResult = false;
+    return true;
+  }
+
+  switch (aData.CharAt(aFlag.Length() + 1)) {
+    case '1':
+    case 't': //true
+    case 'y': //yes
+      aResult = true;
+      return true;
+
+    case '0':
+    case 'f': //false
+    case 'n': //no
+      aResult = false;
+      return true;
+  }
+
+  return false;
+}
+
+enum TriState
+{
+  eUnspecified,
+  eBad,
+  eOK
+};
+
+/**
+ * Check for a modifier flag of the following form:
+ *   "flag=string"
+ *   "flag!=string"
+ * @param aFlag The flag to compare.
+ * @param aData The tokenized data to check; this is lowercased
+ *              before being passed in.
+ * @param aValue The value that is expected.
+ * @param aResult If this is "ok" when passed in, this is left alone.
+ *                Otherwise if the flag is found it is set to eBad or eOK.
+ * @return Whether the flag was handled.
+ */
+static bool
+CheckStringFlag(const nsSubstring& aFlag, const nsSubstring& aData,
+                const nsSubstring& aValue, TriState& aResult)
+{
+  if (aData.Length() < aFlag.Length() + 1) {
+    return false;
+  }
+
+  if (!StringBeginsWith(aData, aFlag)) {
+    return false;
+  }
+
+  bool comparison = true;
+  if (aData[aFlag.Length()] != '=') {
+    if (aData[aFlag.Length()] == '!' &&
+        aData.Length() >= aFlag.Length() + 2 &&
+        aData[aFlag.Length() + 1] == '=') {
+      comparison = false;
+    } else {
+      return false;
+    }
+  }
+
+  if (aResult != eOK) {
+    nsDependentSubstring testdata =
+      Substring(aData, aFlag.Length() + (comparison ? 1 : 2));
+    if (testdata.Equals(aValue)) {
+      aResult = comparison ? eOK : eBad;
+    } else {
+      aResult = comparison ? eBad : eOK;
+    }
+  }
+
+  return true;
+}
+
+/**
+ * Check for a modifier flag of the following form:
+ *   "flag=version"
+ *   "flag<=version"
+ *   "flag<version"
+ *   "flag>=version"
+ *   "flag>version"
+ * @param aFlag The flag to compare.
+ * @param aData The tokenized data to check; this is lowercased
+ *              before being passed in.
+ * @param aValue The value that is expected. If this is empty then no
+ *               comparison will match.
+ * @param aResult If this is eOK when passed in, this is left alone.
+ *                Otherwise if the flag is found it is set to eBad or eOK.
+ * @return Whether the flag was handled.
+ */
+
+#define COMPARE_EQ    1 << 0
+#define COMPARE_LT    1 << 1
+#define COMPARE_GT    1 << 2
+
+static bool
+CheckVersionFlag(const nsString& aFlag, const nsString& aData,
+                 const nsString& aValue, TriState& aResult)
+{
+  if (aData.Length() < aFlag.Length() + 2) {
+    return false;
+  }
+
+  if (!StringBeginsWith(aData, aFlag)) {
+    return false;
+  }
+
+  if (aValue.Length() == 0) {
+    if (aResult != eOK) {
+      aResult = eBad;
+    }
+    return true;
+  }
+
+  uint32_t comparison;
+  nsAutoString testdata;
+
+  switch (aData[aFlag.Length()]) {
+    case '=':
+      comparison = COMPARE_EQ;
+      testdata = Substring(aData, aFlag.Length() + 1);
+      break;
+
+    case '<':
+      if (aData[aFlag.Length() + 1] == '=') {
+        comparison = COMPARE_EQ | COMPARE_LT;
+        testdata = Substring(aData, aFlag.Length() + 2);
+      } else {
+        comparison = COMPARE_LT;
+        testdata = Substring(aData, aFlag.Length() + 1);
+      }
+      break;
+
+    case '>':
+      if (aData[aFlag.Length() + 1] == '=') {
+        comparison = COMPARE_EQ | COMPARE_GT;
+        testdata = Substring(aData, aFlag.Length() + 2);
+      } else {
+        comparison = COMPARE_GT;
+        testdata = Substring(aData, aFlag.Length() + 1);
+      }
+      break;
+
+    default:
+      return false;
+  }
+
+  if (testdata.Length() == 0) {
+    return false;
+  }
+
+  if (aResult != eOK) {
+    int32_t c = mozilla::CompareVersions(NS_ConvertUTF16toUTF8(aValue).get(),
+                                         NS_ConvertUTF16toUTF8(testdata).get());
+    if ((c == 0 && comparison & COMPARE_EQ) ||
+        (c < 0 && comparison & COMPARE_LT) ||
+        (c > 0 && comparison & COMPARE_GT)) {
+      aResult = eOK;
+    } else {
+      aResult = eBad;
+    }
+  }
+
+  return true;
+}
+
+// In-place conversion of ascii characters to lower case
+static void
+ToLowerCase(char* aToken)
+{
+  for (; *aToken; ++aToken) {
+    *aToken = NS_ToLower(*aToken);
+  }
+}
+
+namespace {
+
+struct CachedDirective
+{
+  int lineno;
+  char* argv[4];
+};
+
+} // namespace
+
+
+/**
+ * For XPT-Only mode, the parser handles only directives of "manifest"
+ * and "interfaces", and always call the function given by |xptonlyfunc|
+ * variable of struct |ManifestDirective|.
+ *
+ * This function is safe to be called before the component manager is
+ * ready if aXPTOnly is true for it don't invoke any component during
+ * parsing.
+ */
+void
+ParseManifest(NSLocationType aType, FileLocation& aFile, char* aBuf,
+              bool aChromeOnly, bool aXPTOnly)
+{
+  nsComponentManagerImpl::ManifestProcessingContext mgrcx(aType, aFile,
+                                                          aChromeOnly);
+  nsChromeRegistry::ManifestProcessingContext chromecx(aType, aFile);
+  nsresult rv;
+
+  NS_NAMED_LITERAL_STRING(kPlatform, "platform");
+  NS_NAMED_LITERAL_STRING(kContentAccessible, "contentaccessible");
+  NS_NAMED_LITERAL_STRING(kRemoteEnabled, "remoteenabled");
+  NS_NAMED_LITERAL_STRING(kRemoteRequired, "remoterequired");
+  NS_NAMED_LITERAL_STRING(kApplication, "application");
+  NS_NAMED_LITERAL_STRING(kAppVersion, "appversion");
+  NS_NAMED_LITERAL_STRING(kGeckoVersion, "platformversion");
+  NS_NAMED_LITERAL_STRING(kOs, "os");
+  NS_NAMED_LITERAL_STRING(kOsVersion, "osversion");
+  NS_NAMED_LITERAL_STRING(kABI, "abi");
+  NS_NAMED_LITERAL_STRING(kProcess, "process");
+#if defined(MOZ_WIDGET_ANDROID)
+  NS_NAMED_LITERAL_STRING(kTablet, "tablet");
+#endif
+
+  NS_NAMED_LITERAL_STRING(kMain, "main");
+  NS_NAMED_LITERAL_STRING(kContent, "content");
+
+  // Obsolete
+  NS_NAMED_LITERAL_STRING(kXPCNativeWrappers, "xpcnativewrappers");
+
+  nsAutoString appID;
+  nsAutoString appVersion;
+  nsAutoString geckoVersion;
+  nsAutoString osTarget;
+  nsAutoString abi;
+  nsAutoString process;
+
+  nsCOMPtr<nsIXULAppInfo> xapp;
+  if (!aXPTOnly) {
+    // Avoid to create any component for XPT only mode.
+    // No xapp means no ID, version, ..., modifiers checking.
+    xapp = do_GetService(XULAPPINFO_SERVICE_CONTRACTID);
+  }
+  if (xapp) {
+    nsAutoCString s;
+    rv = xapp->GetID(s);
+    if (NS_SUCCEEDED(rv)) {
+      CopyUTF8toUTF16(s, appID);
+    }
+
+    rv = xapp->GetVersion(s);
+    if (NS_SUCCEEDED(rv)) {
+      CopyUTF8toUTF16(s, appVersion);
+    }
+
+    rv = xapp->GetPlatformVersion(s);
+    if (NS_SUCCEEDED(rv)) {
+      CopyUTF8toUTF16(s, geckoVersion);
+    }
+
+    nsCOMPtr<nsIXULRuntime> xruntime(do_QueryInterface(xapp));
+    if (xruntime) {
+      rv = xruntime->GetOS(s);
+      if (NS_SUCCEEDED(rv)) {
+        ToLowerCase(s);
+        CopyUTF8toUTF16(s, osTarget);
+      }
+
+      rv = xruntime->GetXPCOMABI(s);
+      if (NS_SUCCEEDED(rv) && osTarget.Length()) {
+        ToLowerCase(s);
+        CopyUTF8toUTF16(s, abi);
+        abi.Insert(char16_t('_'), 0);
+        abi.Insert(osTarget, 0);
+      }
+    }
+  }
+
+  nsAutoString osVersion;
+#if defined(XP_WIN)
+#pragma warning(push)
+#pragma warning(disable:4996) // VC12+ deprecates GetVersionEx
+  OSVERSIONINFO info = { sizeof(OSVERSIONINFO) };
+  if (GetVersionEx(&info)) {
+    nsTextFormatter::ssprintf(osVersion, u"%ld.%ld",
+                              info.dwMajorVersion,
+                              info.dwMinorVersion);
+  }
+#pragma warning(pop)
+#elif defined(MOZ_WIDGET_COCOA)
+  SInt32 majorVersion = nsCocoaFeatures::OSXVersionMajor();
+  SInt32 minorVersion = nsCocoaFeatures::OSXVersionMinor();
+  nsTextFormatter::ssprintf(osVersion, u"%ld.%ld",
+                            majorVersion,
+                            minorVersion);
+#elif defined(MOZ_WIDGET_GTK)
+  nsTextFormatter::ssprintf(osVersion, u"%ld.%ld",
+                            gtk_major_version,
+                            gtk_minor_version);
+#elif defined(MOZ_WIDGET_ANDROID)
+  bool isTablet = false;
+  if (mozilla::AndroidBridge::Bridge()) {
+    mozilla::AndroidBridge::Bridge()->GetStaticStringField("android/os/Build$VERSION",
+                                                           "RELEASE",
+                                                           osVersion);
+    isTablet = java::GeckoAppShell::IsTablet();
+  }
+#endif
+
+  if (XRE_IsContentProcess()) {
+    process = kContent;
+  } else {
+    process = kMain;
+  }
+
+  // Because contracts must be registered after CIDs, we save and process them
+  // at the end.
+  nsTArray<CachedDirective> contracts;
+
+  char* token;
+  char* newline = aBuf;
+  uint32_t line = 0;
+
+  // outer loop tokenizes by newline
+  while (*newline) {
+    while (*newline && IsNewline(*newline)) {
+      ++newline;
+      ++line;
+    }
+    if (!*newline) {
+      break;
+    }
+
+    token = newline;
+    while (*newline && !IsNewline(*newline)) {
+      ++newline;
+    }
+
+    if (*newline) {
+      *newline = '\0';
+      ++newline;
+    }
+    ++line;
+
+    if (*token == '#') { // ignore lines that begin with # as comments
+      continue;
+    }
+
+    char* whitespace = token;
+    token = nsCRT::strtok(whitespace, kWhitespace, &whitespace);
+    if (!token) {
+      continue;
+    }
+
+    const ManifestDirective* directive = nullptr;
+    for (const ManifestDirective* d = kParsingTable;
+         d < ArrayEnd(kParsingTable);
+         ++d) {
+      if (!strcmp(d->directive, token) &&
+          (!aXPTOnly || d->xptonlyfunc)) {
+        directive = d;
+        break;
+      }
+    }
+
+    if (!directive) {
+      LogMessageWithContext(aFile, line,
+                            "Ignoring unrecognized chrome manifest directive '%s'.",
+                            token);
+      continue;
+    }
+
+    if (!directive->allowbootstrap && NS_BOOTSTRAPPED_LOCATION == aType) {
+      LogMessageWithContext(aFile, line,
+                            "Bootstrapped manifest not allowed to use '%s' directive.",
+                            token);
+      continue;
+    }
+
+#ifndef MOZ_BINARY_EXTENSIONS
+    if (directive->apponly && NS_APP_LOCATION != aType) {
+      LogMessageWithContext(aFile, line,
+                            "Only application manifests may use the '%s' directive.", token);
+      continue;
+    }
+#endif
+
+    if (directive->componentonly && NS_SKIN_LOCATION == aType) {
+      LogMessageWithContext(aFile, line,
+                            "Skin manifest not allowed to use '%s' directive.",
+                            token);
+      continue;
+    }
+
+    NS_ASSERTION(directive->argc < 4, "Need to reset argv array length");
+    char* argv[4];
+    for (int i = 0; i < directive->argc; ++i) {
+      argv[i] = nsCRT::strtok(whitespace, kWhitespace, &whitespace);
+    }
+
+    if (!argv[directive->argc - 1]) {
+      LogMessageWithContext(aFile, line,
+                            "Not enough arguments for chrome manifest directive '%s', expected %i.",
+                            token, directive->argc);
+      continue;
+    }
+
+    bool ok = true;
+    TriState stAppVersion = eUnspecified;
+    TriState stGeckoVersion = eUnspecified;
+    TriState stApp = eUnspecified;
+    TriState stOsVersion = eUnspecified;
+    TriState stOs = eUnspecified;
+    TriState stABI = eUnspecified;
+    TriState stProcess = eUnspecified;
+#if defined(MOZ_WIDGET_ANDROID)
+    TriState stTablet = eUnspecified;
+#endif
+    int flags = 0;
+
+    while ((token = nsCRT::strtok(whitespace, kWhitespace, &whitespace)) &&
+           ok) {
+      ToLowerCase(token);
+      NS_ConvertASCIItoUTF16 wtoken(token);
+
+      if (CheckStringFlag(kApplication, wtoken, appID, stApp) ||
+          CheckStringFlag(kOs, wtoken, osTarget, stOs) ||
+          CheckStringFlag(kABI, wtoken, abi, stABI) ||
+          CheckStringFlag(kProcess, wtoken, process, stProcess) ||
+          CheckVersionFlag(kOsVersion, wtoken, osVersion, stOsVersion) ||
+          CheckVersionFlag(kAppVersion, wtoken, appVersion, stAppVersion) ||
+          CheckVersionFlag(kGeckoVersion, wtoken, geckoVersion, stGeckoVersion)) {
+        continue;
+      }
+
+#if defined(MOZ_WIDGET_ANDROID)
+      bool tablet = false;
+      if (CheckFlag(kTablet, wtoken, tablet)) {
+        stTablet = (tablet == isTablet) ? eOK : eBad;
+        continue;
+      }
+#endif
+
+      if (directive->contentflags) {
+        bool flag;
+        if (CheckFlag(kPlatform, wtoken, flag)) {
+          if (flag)
+            flags |= nsChromeRegistry::PLATFORM_PACKAGE;
+          continue;
+        }
+        if (CheckFlag(kContentAccessible, wtoken, flag)) {
+          if (flag)
+            flags |= nsChromeRegistry::CONTENT_ACCESSIBLE;
+          continue;
+        }
+        if (CheckFlag(kRemoteEnabled, wtoken, flag)) {
+          if (flag)
+            flags |= nsChromeRegistry::REMOTE_ALLOWED;
+          continue;
+        }
+        if (CheckFlag(kRemoteRequired, wtoken, flag)) {
+          if (flag)
+            flags |= nsChromeRegistry::REMOTE_REQUIRED;
+          continue;
+        }
+      }
+
+      bool xpcNativeWrappers = true; // Dummy for CheckFlag.
+      if (CheckFlag(kXPCNativeWrappers, wtoken, xpcNativeWrappers)) {
+        LogMessageWithContext(aFile, line,
+                              "Ignoring obsolete chrome registration modifier '%s'.",
+                              token);
+        continue;
+      }
+
+      LogMessageWithContext(aFile, line,
+                            "Unrecognized chrome manifest modifier '%s'.",
+                            token);
+      ok = false;
+    }
+
+    if (!ok ||
+        stApp == eBad ||
+        stAppVersion == eBad ||
+        stGeckoVersion == eBad ||
+        stOs == eBad ||
+        stOsVersion == eBad ||
+#ifdef MOZ_WIDGET_ANDROID
+        stTablet == eBad ||
+#endif
+        stABI == eBad ||
+        stProcess == eBad) {
+      continue;
+    }
+
+    if (directive->regfunc) {
+      if (GeckoProcessType_Default != XRE_GetProcessType()) {
+        continue;
+      }
+
+      if (!nsChromeRegistry::gChromeRegistry) {
+        nsCOMPtr<nsIChromeRegistry> cr =
+          mozilla::services::GetChromeRegistryService();
+        if (!nsChromeRegistry::gChromeRegistry) {
+          LogMessageWithContext(aFile, line,
+                                "Chrome registry isn't available yet.");
+          continue;
+        }
+      }
+
+      (nsChromeRegistry::gChromeRegistry->*(directive->regfunc))(
+        chromecx, line, argv, flags);
+    } else if (directive->ischrome || !aChromeOnly) {
+      if (directive->isContract) {
+        CachedDirective* cd = contracts.AppendElement();
+        cd->lineno = line;
+        cd->argv[0] = argv[0];
+        cd->argv[1] = argv[1];
+      } else {
+        (nsComponentManagerImpl::gComponentManager->*(directive->mgrfunc))(
+          mgrcx, line, argv);
+      }
+    }
+  }
+
+  for (uint32_t i = 0; i < contracts.Length(); ++i) {
+    CachedDirective& d = contracts[i];
+    nsComponentManagerImpl::gComponentManager->ManifestContract(mgrcx,
+                                                                d.lineno,
+                                                                d.argv);
+  }
+}
diff --git a/xpcom/components/ManifestParser.h b/xpcom/components/ManifestParser.h
new file mode 100644
index 000000000..019ec326c
--- /dev/null
+++ b/xpcom/components/ManifestParser.h
@@ -0,0 +1,22 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef ManifestParser_h
+#define ManifestParser_h
+
+#include "nsComponentManager.h"
+#include "nsChromeRegistry.h"
+#include "mozilla/FileLocation.h"
+
+void ParseManifest(NSLocationType aType, mozilla::FileLocation& aFile,
+                   char* aBuf, bool aChromeOnly, bool aXPTOnly = false);
+
+void LogMessage(const char* aMsg, ...);
+
+void LogMessageWithContext(mozilla::FileLocation& aFile,
+                           uint32_t aLineNumber, const char* aMsg, ...);
+
+#endif // ManifestParser_h
diff --git a/xpcom/components/Module.h b/xpcom/components/Module.h
new file mode 100644
index 000000000..21d07e82e
--- /dev/null
+++ b/xpcom/components/Module.h
@@ -0,0 +1,157 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_Module_h
+#define mozilla_Module_h
+
+#include "nscore.h"
+#include "nsID.h"
+#include "nsIFactory.h"
+#include "nsCOMPtr.h" // for already_AddRefed
+
+namespace mozilla {
+
+/**
+ * A module implements one or more XPCOM components. This structure is used
+ * for both binary and script modules, but the registration members
+ * (cids/contractids/categoryentries) are unused for modules which are loaded
+ * via a module loader.
+ */
+struct Module
+{
+  static const unsigned int kVersion = 52;
+
+  struct CIDEntry;
+
+  typedef already_AddRefed<nsIFactory> (*GetFactoryProcPtr)(
+    const Module& module, const CIDEntry& entry);
+
+  typedef nsresult (*ConstructorProcPtr)(nsISupports* aOuter,
+                                         const nsIID& aIID,
+                                         void** aResult);
+
+  typedef nsresult (*LoadFuncPtr)();
+  typedef void (*UnloadFuncPtr)();
+
+  /**
+   * This selector allows CIDEntrys to be marked so that they're only loaded
+   * into certain kinds of processes. Selectors can be combined.
+   */
+  enum ProcessSelector
+  {
+    ANY_PROCESS          = 0x0,
+    MAIN_PROCESS_ONLY    = 0x1,
+    CONTENT_PROCESS_ONLY = 0x2,
+
+    /**
+     * By default, modules are not loaded in the GPU process, even if
+     * ANY_PROCESS is specified. This flag enables a module in the
+     * GPU process.
+     */
+    ALLOW_IN_GPU_PROCESS = 0x4
+  };
+
+  /**
+   * The constructor callback is an implementation detail of the default binary
+   * loader and may be null.
+   */
+  struct CIDEntry
+  {
+    const nsCID* cid;
+    bool service;
+    GetFactoryProcPtr getFactoryProc;
+    ConstructorProcPtr constructorProc;
+    ProcessSelector processSelector;
+  };
+
+  struct ContractIDEntry
+  {
+    const char* contractid;
+    nsID const* cid;
+    ProcessSelector processSelector;
+  };
+
+  struct CategoryEntry
+  {
+    const char* category;
+    const char* entry;
+    const char* value;
+  };
+
+  /**
+   * Binary compatibility check, should be kModuleVersion.
+   */
+  unsigned int mVersion;
+
+  /**
+   * An array of CIDs (class IDs) implemented by this module. The final entry
+   * should be { nullptr }.
+   */
+  const CIDEntry* mCIDs;
+
+  /**
+   * An array of mappings from contractid to CID. The final entry should
+   * be { nullptr }.
+   */
+  const ContractIDEntry* mContractIDs;
+
+  /**
+   * An array of category manager entries. The final entry should be
+   * { nullptr }.
+   */
+  const CategoryEntry* mCategoryEntries;
+
+  /**
+   * When the component manager tries to get the factory for a CID, it first
+   * checks for this module-level getfactory callback. If this function is
+   * not implemented, it checks the CIDEntry getfactory callback. If that is
+   * also nullptr, a generic factory is generated using the CIDEntry
+   * constructor callback which must be non-nullptr.
+   */
+  GetFactoryProcPtr getFactoryProc;
+
+  /**
+   * Optional Function which are called when this module is loaded and
+   * at shutdown. These are not C++ constructor/destructors to avoid
+   * calling them too early in startup or too late in shutdown.
+   */
+  LoadFuncPtr loadProc;
+  UnloadFuncPtr unloadProc;
+
+  /**
+   * Optional flags which control whether the module loads on a process-type
+   * basis.
+   */
+  ProcessSelector selector;
+};
+
+} // namespace mozilla
+
+#if defined(MOZILLA_INTERNAL_API)
+#  define NSMODULE_NAME(_name) _name##_NSModule
+#  if defined(_MSC_VER)
+#    pragma section(".kPStaticModules$M", read)
+#    pragma comment(linker, "/merge:.kPStaticModules=.rdata")
+#    define NSMODULE_SECTION __declspec(allocate(".kPStaticModules$M"), dllexport)
+#  elif defined(__GNUC__)
+#    if defined(__ELF__)
+#      define NSMODULE_SECTION __attribute__((section(".kPStaticModules"), visibility("default")))
+#    elif defined(__MACH__)
+#      define NSMODULE_SECTION __attribute__((section("__DATA, .kPStaticModules"), visibility("default")))
+#    elif defined (_WIN32)
+#      define NSMODULE_SECTION __attribute__((section(".kPStaticModules"), dllexport))
+#    endif
+#  endif
+#  if !defined(NSMODULE_SECTION)
+#    error Do not know how to define sections.
+#  endif
+#  define NSMODULE_DEFN(_name) extern NSMODULE_SECTION mozilla::Module const *const NSMODULE_NAME(_name)
+#else
+#  define NSMODULE_NAME(_name) NSModule
+#  define NSMODULE_DEFN(_name) extern "C" NS_EXPORT mozilla::Module const *const NSModule
+#endif
+
+#endif // mozilla_Module_h
diff --git a/xpcom/components/ModuleLoader.h b/xpcom/components/ModuleLoader.h
new file mode 100644
index 000000000..c2c920d4d
--- /dev/null
+++ b/xpcom/components/ModuleLoader.h
@@ -0,0 +1,44 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_ModuleLoader_h
+#define mozilla_ModuleLoader_h
+
+#include "nsISupports.h"
+#include "mozilla/Module.h"
+#include "mozilla/FileLocation.h"
+
+#define MOZILLA_MODULELOADER_PSEUDO_IID \
+{ 0xD951A8CE, 0x6E9F, 0x464F, \
+  { 0x8A, 0xC8, 0x14, 0x61, 0xC0, 0xD3, 0x63, 0xC8 } }
+
+namespace mozilla {
+
+/**
+ * Module loaders are responsible for loading a component file. The static
+ * component loader is special and does not use this abstract interface.
+ *
+ * @note Implementations of this interface should be threadsafe,
+ *       methods may be called from any thread.
+ */
+class ModuleLoader : public nsISupports
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(MOZILLA_MODULELOADER_PSEUDO_IID)
+
+  /**
+   * Return the module for a specified file. The caller should cache
+   * the module: the implementer should not expect for the same file
+   * to be loaded multiple times. The Module object should either be
+   * statically or permanently allocated; it will not be freed.
+   */
+  virtual const Module* LoadModule(mozilla::FileLocation& aFile) = 0;
+};
+NS_DEFINE_STATIC_IID_ACCESSOR(ModuleLoader, MOZILLA_MODULELOADER_PSEUDO_IID)
+
+} // namespace mozilla
+
+#endif // mozilla_ModuleLoader_h
diff --git a/xpcom/components/ModuleUtils.h b/xpcom/components/ModuleUtils.h
new file mode 100644
index 000000000..9c31ed76b
--- /dev/null
+++ b/xpcom/components/ModuleUtils.h
@@ -0,0 +1,98 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_GenericModule_h
+#define mozilla_GenericModule_h
+
+#include "mozilla/Attributes.h"
+#include "mozilla/Module.h"
+
+#define NS_GENERIC_FACTORY_CONSTRUCTOR(_InstanceClass)                        \
+static nsresult                                                               \
+_InstanceClass##Constructor(nsISupports *aOuter, REFNSIID aIID,               \
+                            void **aResult)                                   \
+{                                                                             \
+  RefPtr<_InstanceClass> inst;                                                \
+                                                                              \
+  *aResult = nullptr;                                                         \
+  if (nullptr != aOuter) {                                                    \
+    return NS_ERROR_NO_AGGREGATION;                                           \
+  }                                                                           \
+                                                                              \
+  inst = new _InstanceClass();                                                \
+  return inst->QueryInterface(aIID, aResult);                                 \
+}
+
+#define NS_GENERIC_FACTORY_CONSTRUCTOR_INIT(_InstanceClass, _InitMethod)      \
+static nsresult                                                               \
+_InstanceClass##Constructor(nsISupports *aOuter, REFNSIID aIID,               \
+                            void **aResult)                                   \
+{                                                                             \
+  nsresult rv;                                                                \
+                                                                              \
+  RefPtr<_InstanceClass> inst;                                                \
+                                                                              \
+  *aResult = nullptr;                                                         \
+  if (nullptr != aOuter) {                                                    \
+    return NS_ERROR_NO_AGGREGATION;                                           \
+  }                                                                           \
+                                                                              \
+  inst = new _InstanceClass();                                                \
+  rv = inst->_InitMethod();                                                   \
+  if (NS_SUCCEEDED(rv)) {                                                     \
+    rv = inst->QueryInterface(aIID, aResult);                                 \
+  }                                                                           \
+                                                                              \
+  return rv;                                                                  \
+}
+
+// 'Constructor' that uses an existing getter function that gets a singleton.
+// NOTE: assumes that getter does an AddRef - so additional AddRef is not done.
+#define NS_GENERIC_FACTORY_SINGLETON_CONSTRUCTOR(_InstanceClass, _GetterProc) \
+static nsresult                                                               \
+_InstanceClass##Constructor(nsISupports *aOuter, REFNSIID aIID,               \
+                            void **aResult)                                   \
+{                                                                             \
+  RefPtr<_InstanceClass> inst;                                                \
+                                                                              \
+  *aResult = nullptr;                                                         \
+  if (nullptr != aOuter) {                                                    \
+    return NS_ERROR_NO_AGGREGATION;                                           \
+  }                                                                           \
+                                                                              \
+  inst = already_AddRefed<_InstanceClass>(_GetterProc());                     \
+  if (nullptr == inst) {                                                      \
+    return NS_ERROR_OUT_OF_MEMORY;                                            \
+  }                                                                           \
+  return inst->QueryInterface(aIID, aResult);                                 \
+}
+
+#ifndef MOZILLA_INTERNAL_API
+
+#include "nsIModule.h"
+#include "nsISupportsUtils.h"
+
+namespace mozilla {
+
+class GenericModule final : public nsIModule
+{
+  ~GenericModule() {}
+
+public:
+  explicit GenericModule(const mozilla::Module* aData) : mData(aData) {}
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIMODULE
+
+private:
+  const mozilla::Module* mData;
+};
+
+} // namespace mozilla
+
+#endif
+
+#endif // mozilla_GenericModule_h
diff --git a/xpcom/components/moz.build b/xpcom/components/moz.build
new file mode 100644
index 000000000..73a85cb3b
--- /dev/null
+++ b/xpcom/components/moz.build
@@ -0,0 +1,55 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+XPIDL_SOURCES += [
+    'nsICategoryManager.idl',
+    'nsIClassInfo.idl',
+    'nsIComponentManager.idl',
+    'nsIComponentRegistrar.idl',
+    'nsIFactory.idl',
+    'nsIModule.idl',
+    'nsIServiceManager.idl',
+]
+
+XPIDL_MODULE = 'xpcom_components'
+
+EXPORTS += [
+    'nsCategoryManagerUtils.h',
+]
+
+EXPORTS.mozilla += [
+    'Module.h',
+    'ModuleLoader.h',
+    'ModuleUtils.h',
+]
+
+# nsCategoryManager.cpp and nsComponentManager.cpp cannot be built in
+# unified mode because they use thea PL_ARENA_CONST_ALIGN_MASK macro
+# with plarena.h.
+SOURCES += [
+    'nsCategoryManager.cpp',
+    'nsComponentManager.cpp',
+]
+
+UNIFIED_SOURCES += [
+    'ManifestParser.cpp',
+    'nsNativeModuleLoader.cpp',
+]
+
+FINAL_LIBRARY = 'xul'
+
+LOCAL_INCLUDES += [
+    '!..',
+    '../base',
+    '../build',
+    '../ds',
+    '../reflect/xptinfo',
+    '/chrome',
+    '/modules/libjar',
+]
+
+if 'gtk' in CONFIG['MOZ_WIDGET_TOOLKIT']:
+    CXXFLAGS += CONFIG['TK_CFLAGS']
diff --git a/xpcom/components/nsCategoryManager.cpp b/xpcom/components/nsCategoryManager.cpp
new file mode 100644
index 000000000..527c78719
--- /dev/null
+++ b/xpcom/components/nsCategoryManager.cpp
@@ -0,0 +1,832 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#define PL_ARENA_CONST_ALIGN_MASK 7
+
+#include "nsICategoryManager.h"
+#include "nsCategoryManager.h"
+
+#include "plarena.h"
+#include "prio.h"
+#include "prprf.h"
+#include "prlock.h"
+#include "nsCOMPtr.h"
+#include "nsTHashtable.h"
+#include "nsClassHashtable.h"
+#include "nsIFactory.h"
+#include "nsIStringEnumerator.h"
+#include "nsSupportsPrimitives.h"
+#include "nsComponentManagerUtils.h"
+#include "nsServiceManagerUtils.h"
+#include "nsIObserver.h"
+#include "nsIObserverService.h"
+#include "nsReadableUtils.h"
+#include "nsCRT.h"
+#include "nsQuickSort.h"
+#include "nsEnumeratorUtils.h"
+#include "nsThreadUtils.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Services.h"
+
+#include "ManifestParser.h"
+#include "nsISimpleEnumerator.h"
+
+using namespace mozilla;
+class nsIComponentLoaderManager;
+
+/*
+  CategoryDatabase
+  contains 0 or more 1-1 mappings of string to Category
+  each Category contains 0 or more 1-1 mappings of string keys to string values
+
+  In other words, the CategoryDatabase is a tree, whose root is a hashtable.
+  Internal nodes (or Categories) are hashtables. Leaf nodes are strings.
+
+  The leaf strings are allocated in an arena, because we assume they're not
+  going to change much ;)
+*/
+
+#define NS_CATEGORYMANAGER_ARENA_SIZE (1024 * 8)
+
+// pulled in from nsComponentManager.cpp
+char* ArenaStrdup(const char* aStr, PLArenaPool* aArena);
+
+//
+// BaseStringEnumerator is subclassed by EntryEnumerator and
+// CategoryEnumerator
+//
+class BaseStringEnumerator
+  : public nsISimpleEnumerator
+  , private nsIUTF8StringEnumerator
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISIMPLEENUMERATOR
+  NS_DECL_NSIUTF8STRINGENUMERATOR
+
+protected:
+  // Callback function for NS_QuickSort to sort mArray
+  static int SortCallback(const void*, const void*, void*);
+
+  BaseStringEnumerator()
+    : mArray(nullptr)
+    , mCount(0)
+    , mSimpleCurItem(0)
+    , mStringCurItem(0)
+  {
+  }
+
+  // A virtual destructor is needed here because subclasses of
+  // BaseStringEnumerator do not implement their own Release() method.
+
+  virtual ~BaseStringEnumerator()
+  {
+    delete [] mArray;
+  }
+
+  void Sort();
+
+  const char** mArray;
+  uint32_t mCount;
+  uint32_t mSimpleCurItem;
+  uint32_t mStringCurItem;
+};
+
+NS_IMPL_ISUPPORTS(BaseStringEnumerator, nsISimpleEnumerator,
+                  nsIUTF8StringEnumerator)
+
+NS_IMETHODIMP
+BaseStringEnumerator::HasMoreElements(bool* aResult)
+{
+  *aResult = (mSimpleCurItem < mCount);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+BaseStringEnumerator::GetNext(nsISupports** aResult)
+{
+  if (mSimpleCurItem >= mCount) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsSupportsDependentCString* str =
+    new nsSupportsDependentCString(mArray[mSimpleCurItem++]);
+  if (!str) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  *aResult = str;
+  NS_ADDREF(*aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+BaseStringEnumerator::HasMore(bool* aResult)
+{
+  *aResult = (mStringCurItem < mCount);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+BaseStringEnumerator::GetNext(nsACString& aResult)
+{
+  if (mStringCurItem >= mCount) {
+    return NS_ERROR_FAILURE;
+  }
+
+  aResult = nsDependentCString(mArray[mStringCurItem++]);
+  return NS_OK;
+}
+
+int
+BaseStringEnumerator::SortCallback(const void* aE1, const void* aE2,
+                                   void* /*unused*/)
+{
+  char const* const* s1 = reinterpret_cast<char const* const*>(aE1);
+  char const* const* s2 = reinterpret_cast<char const* const*>(aE2);
+
+  return strcmp(*s1, *s2);
+}
+
+void
+BaseStringEnumerator::Sort()
+{
+  NS_QuickSort(mArray, mCount, sizeof(mArray[0]), SortCallback, nullptr);
+}
+
+//
+// EntryEnumerator is the wrapper that allows nsICategoryManager::EnumerateCategory
+//
+class EntryEnumerator
+  : public BaseStringEnumerator
+{
+public:
+  static EntryEnumerator* Create(nsTHashtable<CategoryLeaf>& aTable);
+};
+
+
+EntryEnumerator*
+EntryEnumerator::Create(nsTHashtable<CategoryLeaf>& aTable)
+{
+  EntryEnumerator* enumObj = new EntryEnumerator();
+  if (!enumObj) {
+    return nullptr;
+  }
+
+  enumObj->mArray = new char const* [aTable.Count()];
+  if (!enumObj->mArray) {
+    delete enumObj;
+    return nullptr;
+  }
+
+  for (auto iter = aTable.Iter(); !iter.Done(); iter.Next()) {
+    CategoryLeaf* leaf = iter.Get();
+    if (leaf->value) {
+      enumObj->mArray[enumObj->mCount++] = leaf->GetKey();
+    }
+  }
+
+  enumObj->Sort();
+
+  return enumObj;
+}
+
+
+//
+// CategoryNode implementations
+//
+
+CategoryNode*
+CategoryNode::Create(PLArenaPool* aArena)
+{
+  return new (aArena) CategoryNode();
+}
+
+CategoryNode::~CategoryNode()
+{
+}
+
+void*
+CategoryNode::operator new(size_t aSize, PLArenaPool* aArena)
+{
+  void* p;
+  PL_ARENA_ALLOCATE(p, aArena, aSize);
+  return p;
+}
+
+nsresult
+CategoryNode::GetLeaf(const char* aEntryName,
+                      char** aResult)
+{
+  MutexAutoLock lock(mLock);
+  nsresult rv = NS_ERROR_NOT_AVAILABLE;
+  CategoryLeaf* ent = mTable.GetEntry(aEntryName);
+
+  if (ent && ent->value) {
+    *aResult = NS_strdup(ent->value);
+    if (*aResult) {
+      rv = NS_OK;
+    }
+  }
+
+  return rv;
+}
+
+nsresult
+CategoryNode::AddLeaf(const char* aEntryName,
+                      const char* aValue,
+                      bool aReplace,
+                      char** aResult,
+                      PLArenaPool* aArena)
+{
+  if (aResult) {
+    *aResult = nullptr;
+  }
+
+  MutexAutoLock lock(mLock);
+  CategoryLeaf* leaf = mTable.GetEntry(aEntryName);
+
+  if (!leaf) {
+    const char* arenaEntryName = ArenaStrdup(aEntryName, aArena);
+    if (!arenaEntryName) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    leaf = mTable.PutEntry(arenaEntryName);
+    if (!leaf) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+  }
+
+  if (leaf->value && !aReplace) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  const char* arenaValue = ArenaStrdup(aValue, aArena);
+  if (!arenaValue) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  if (aResult && leaf->value) {
+    *aResult = ToNewCString(nsDependentCString(leaf->value));
+    if (!*aResult) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+  }
+
+  leaf->value = arenaValue;
+  return NS_OK;
+}
+
+void
+CategoryNode::DeleteLeaf(const char* aEntryName)
+{
+  // we don't throw any errors, because it normally doesn't matter
+  // and it makes JS a lot cleaner
+  MutexAutoLock lock(mLock);
+
+  // we can just remove the entire hash entry without introspection
+  mTable.RemoveEntry(aEntryName);
+}
+
+nsresult
+CategoryNode::Enumerate(nsISimpleEnumerator** aResult)
+{
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  MutexAutoLock lock(mLock);
+  EntryEnumerator* enumObj = EntryEnumerator::Create(mTable);
+
+  if (!enumObj) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  *aResult = enumObj;
+  NS_ADDREF(*aResult);
+  return NS_OK;
+}
+
+size_t
+CategoryNode::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf)
+{
+  // We don't measure the strings pointed to by the entries because the
+  // pointers are non-owning.
+  return mTable.ShallowSizeOfExcludingThis(aMallocSizeOf);
+}
+
+//
+// CategoryEnumerator class
+//
+
+class CategoryEnumerator
+  : public BaseStringEnumerator
+{
+public:
+  static CategoryEnumerator* Create(nsClassHashtable<nsDepCharHashKey,
+                                                     CategoryNode>& aTable);
+};
+
+CategoryEnumerator*
+CategoryEnumerator::Create(nsClassHashtable<nsDepCharHashKey, CategoryNode>&
+                           aTable)
+{
+  CategoryEnumerator* enumObj = new CategoryEnumerator();
+  if (!enumObj) {
+    return nullptr;
+  }
+
+  enumObj->mArray = new const char* [aTable.Count()];
+  if (!enumObj->mArray) {
+    delete enumObj;
+    return nullptr;
+  }
+
+  for (auto iter = aTable.Iter(); !iter.Done(); iter.Next()) {
+    // if a category has no entries, we pretend it doesn't exist
+    CategoryNode* aNode = iter.UserData();
+    if (aNode->Count()) {
+      const char* str = iter.Key();
+      enumObj->mArray[enumObj->mCount++] = str;
+    }
+  }
+
+  return enumObj;
+}
+
+
+//
+// nsCategoryManager implementations
+//
+
+NS_IMPL_QUERY_INTERFACE(nsCategoryManager, nsICategoryManager, nsIMemoryReporter)
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsCategoryManager::AddRef()
+{
+  return 2;
+}
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsCategoryManager::Release()
+{
+  return 1;
+}
+
+nsCategoryManager* nsCategoryManager::gCategoryManager;
+
+/* static */ nsCategoryManager*
+nsCategoryManager::GetSingleton()
+{
+  if (!gCategoryManager) {
+    gCategoryManager = new nsCategoryManager();
+  }
+  return gCategoryManager;
+}
+
+/* static */ void
+nsCategoryManager::Destroy()
+{
+  // The nsMemoryReporterManager gets destroyed before the nsCategoryManager,
+  // so we don't need to unregister the nsCategoryManager as a memory reporter.
+  // In debug builds we assert that unregistering fails, as a way (imperfect
+  // but better than nothing) of testing the "destroyed before" part.
+  MOZ_ASSERT(NS_FAILED(UnregisterWeakMemoryReporter(gCategoryManager)));
+
+  delete gCategoryManager;
+  gCategoryManager = nullptr;
+}
+
+nsresult
+nsCategoryManager::Create(nsISupports* aOuter, REFNSIID aIID, void** aResult)
+{
+  if (aOuter) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+
+  return GetSingleton()->QueryInterface(aIID, aResult);
+}
+
+nsCategoryManager::nsCategoryManager()
+  : mLock("nsCategoryManager")
+  , mSuppressNotifications(false)
+{
+  PL_INIT_ARENA_POOL(&mArena, "CategoryManagerArena",
+                     NS_CATEGORYMANAGER_ARENA_SIZE);
+}
+
+void
+nsCategoryManager::InitMemoryReporter()
+{
+  RegisterWeakMemoryReporter(this);
+}
+
+nsCategoryManager::~nsCategoryManager()
+{
+  // the hashtable contains entries that must be deleted before the arena is
+  // destroyed, or else you will have PRLocks undestroyed and other Really
+  // Bad Stuff (TM)
+  mTable.Clear();
+
+  PL_FinishArenaPool(&mArena);
+}
+
+inline CategoryNode*
+nsCategoryManager::get_category(const char* aName)
+{
+  CategoryNode* node;
+  if (!mTable.Get(aName, &node)) {
+    return nullptr;
+  }
+  return node;
+}
+
+MOZ_DEFINE_MALLOC_SIZE_OF(CategoryManagerMallocSizeOf)
+
+NS_IMETHODIMP
+nsCategoryManager::CollectReports(nsIHandleReportCallback* aHandleReport,
+                                  nsISupports* aData, bool aAnonymize)
+{
+  MOZ_COLLECT_REPORT(
+    "explicit/xpcom/category-manager", KIND_HEAP, UNITS_BYTES,
+    SizeOfIncludingThis(CategoryManagerMallocSizeOf),
+    "Memory used for the XPCOM category manager.");
+
+  return NS_OK;
+}
+
+size_t
+nsCategoryManager::SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf)
+{
+  size_t n = aMallocSizeOf(this);
+
+  n += PL_SizeOfArenaPoolExcludingPool(&mArena, aMallocSizeOf);
+
+  n += mTable.ShallowSizeOfExcludingThis(aMallocSizeOf);
+  for (auto iter = mTable.ConstIter(); !iter.Done(); iter.Next()) {
+    // We don't measure the key string because it's a non-owning pointer.
+    n += iter.Data()->SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  return n;
+}
+
+namespace {
+
+class CategoryNotificationRunnable : public Runnable
+{
+public:
+  CategoryNotificationRunnable(nsISupports* aSubject,
+                               const char* aTopic,
+                               const char* aData)
+    : mSubject(aSubject)
+    , mTopic(aTopic)
+    , mData(aData)
+  {
+  }
+
+  NS_DECL_NSIRUNNABLE
+
+private:
+  nsCOMPtr<nsISupports> mSubject;
+  const char* mTopic;
+  NS_ConvertUTF8toUTF16 mData;
+};
+
+NS_IMETHODIMP
+CategoryNotificationRunnable::Run()
+{
+  nsCOMPtr<nsIObserverService> observerService =
+    mozilla::services::GetObserverService();
+  if (observerService) {
+    observerService->NotifyObservers(mSubject, mTopic, mData.get());
+  }
+
+  return NS_OK;
+}
+
+} // namespace
+
+
+void
+nsCategoryManager::NotifyObservers(const char* aTopic,
+                                   const char* aCategoryName,
+                                   const char* aEntryName)
+{
+  if (mSuppressNotifications) {
+    return;
+  }
+
+  RefPtr<CategoryNotificationRunnable> r;
+
+  if (aEntryName) {
+    nsCOMPtr<nsISupportsCString> entry =
+      do_CreateInstance(NS_SUPPORTS_CSTRING_CONTRACTID);
+    if (!entry) {
+      return;
+    }
+
+    nsresult rv = entry->SetData(nsDependentCString(aEntryName));
+    if (NS_FAILED(rv)) {
+      return;
+    }
+
+    r = new CategoryNotificationRunnable(entry, aTopic, aCategoryName);
+  } else {
+    r = new CategoryNotificationRunnable(NS_ISUPPORTS_CAST(nsICategoryManager*,
+                                                           this),
+                                         aTopic, aCategoryName);
+  }
+
+  NS_DispatchToMainThread(r);
+}
+
+NS_IMETHODIMP
+nsCategoryManager::GetCategoryEntry(const char* aCategoryName,
+                                    const char* aEntryName,
+                                    char** aResult)
+{
+  if (NS_WARN_IF(!aCategoryName) ||
+      NS_WARN_IF(!aEntryName) ||
+      NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsresult status = NS_ERROR_NOT_AVAILABLE;
+
+  CategoryNode* category;
+  {
+    MutexAutoLock lock(mLock);
+    category = get_category(aCategoryName);
+  }
+
+  if (category) {
+    status = category->GetLeaf(aEntryName, aResult);
+  }
+
+  return status;
+}
+
+NS_IMETHODIMP
+nsCategoryManager::AddCategoryEntry(const char* aCategoryName,
+                                    const char* aEntryName,
+                                    const char* aValue,
+                                    bool aPersist,
+                                    bool aReplace,
+                                    char** aResult)
+{
+  if (aPersist) {
+    NS_ERROR("Category manager doesn't support persistence.");
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  AddCategoryEntry(aCategoryName, aEntryName, aValue, aReplace, aResult);
+  return NS_OK;
+}
+
+void
+nsCategoryManager::AddCategoryEntry(const char* aCategoryName,
+                                    const char* aEntryName,
+                                    const char* aValue,
+                                    bool aReplace,
+                                    char** aOldValue)
+{
+  if (aOldValue) {
+    *aOldValue = nullptr;
+  }
+
+  // Before we can insert a new entry, we'll need to
+  //  find the |CategoryNode| to put it in...
+  CategoryNode* category;
+  {
+    MutexAutoLock lock(mLock);
+    category = get_category(aCategoryName);
+
+    if (!category) {
+      // That category doesn't exist yet; let's make it.
+      category = CategoryNode::Create(&mArena);
+
+      char* categoryName = ArenaStrdup(aCategoryName, &mArena);
+      mTable.Put(categoryName, category);
+    }
+  }
+
+  if (!category) {
+    return;
+  }
+
+  // We will need the return value of AddLeaf even if the called doesn't want it
+  char* oldEntry = nullptr;
+
+  nsresult rv = category->AddLeaf(aEntryName,
+                                  aValue,
+                                  aReplace,
+                                  &oldEntry,
+                                  &mArena);
+
+  if (NS_SUCCEEDED(rv)) {
+    if (oldEntry) {
+      NotifyObservers(NS_XPCOM_CATEGORY_ENTRY_REMOVED_OBSERVER_ID,
+                      aCategoryName, aEntryName);
+    }
+    NotifyObservers(NS_XPCOM_CATEGORY_ENTRY_ADDED_OBSERVER_ID,
+                    aCategoryName, aEntryName);
+
+    if (aOldValue) {
+      *aOldValue = oldEntry;
+    } else {
+      free(oldEntry);
+    }
+  }
+}
+
+NS_IMETHODIMP
+nsCategoryManager::DeleteCategoryEntry(const char* aCategoryName,
+                                       const char* aEntryName,
+                                       bool aDontPersist)
+{
+  if (NS_WARN_IF(!aCategoryName) ||
+      NS_WARN_IF(!aEntryName)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  /*
+    Note: no errors are reported since failure to delete
+    probably won't hurt you, and returning errors seriously
+    inconveniences JS clients
+  */
+
+  CategoryNode* category;
+  {
+    MutexAutoLock lock(mLock);
+    category = get_category(aCategoryName);
+  }
+
+  if (category) {
+    category->DeleteLeaf(aEntryName);
+
+    NotifyObservers(NS_XPCOM_CATEGORY_ENTRY_REMOVED_OBSERVER_ID,
+                    aCategoryName, aEntryName);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsCategoryManager::DeleteCategory(const char* aCategoryName)
+{
+  if (NS_WARN_IF(!aCategoryName)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // the categories are arena-allocated, so we don't
+  // actually delete them. We just remove all of the
+  // leaf nodes.
+
+  CategoryNode* category;
+  {
+    MutexAutoLock lock(mLock);
+    category = get_category(aCategoryName);
+  }
+
+  if (category) {
+    category->Clear();
+    NotifyObservers(NS_XPCOM_CATEGORY_CLEARED_OBSERVER_ID,
+                    aCategoryName, nullptr);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsCategoryManager::EnumerateCategory(const char* aCategoryName,
+                                     nsISimpleEnumerator** aResult)
+{
+  if (NS_WARN_IF(!aCategoryName) ||
+      NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  CategoryNode* category;
+  {
+    MutexAutoLock lock(mLock);
+    category = get_category(aCategoryName);
+  }
+
+  if (!category) {
+    return NS_NewEmptyEnumerator(aResult);
+  }
+
+  return category->Enumerate(aResult);
+}
+
+NS_IMETHODIMP
+nsCategoryManager::EnumerateCategories(nsISimpleEnumerator** aResult)
+{
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  MutexAutoLock lock(mLock);
+  CategoryEnumerator* enumObj = CategoryEnumerator::Create(mTable);
+
+  if (!enumObj) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  *aResult = enumObj;
+  NS_ADDREF(*aResult);
+  return NS_OK;
+}
+
+struct writecat_struct
+{
+  PRFileDesc* fd;
+  bool        success;
+};
+
+nsresult
+nsCategoryManager::SuppressNotifications(bool aSuppress)
+{
+  mSuppressNotifications = aSuppress;
+  return NS_OK;
+}
+
+/*
+ * CreateServicesFromCategory()
+ *
+ * Given a category, this convenience functions enumerates the category and
+ * creates a service of every CID or ContractID registered under the category.
+ * If observerTopic is non null and the service implements nsIObserver,
+ * this will attempt to notify the observer with the origin, observerTopic string
+ * as parameter.
+ */
+void
+NS_CreateServicesFromCategory(const char* aCategory,
+                              nsISupports* aOrigin,
+                              const char* aObserverTopic,
+                              const char16_t* aObserverData)
+{
+  nsresult rv;
+
+  nsCOMPtr<nsICategoryManager> categoryManager =
+    do_GetService("@mozilla.org/categorymanager;1");
+  if (!categoryManager) {
+    return;
+  }
+
+  nsCOMPtr<nsISimpleEnumerator> enumerator;
+  rv = categoryManager->EnumerateCategory(aCategory,
+                                          getter_AddRefs(enumerator));
+  if (NS_FAILED(rv)) {
+    return;
+  }
+
+  nsCOMPtr<nsIUTF8StringEnumerator> senumerator =
+    do_QueryInterface(enumerator);
+  if (!senumerator) {
+    NS_WARNING("Category enumerator doesn't support nsIUTF8StringEnumerator.");
+    return;
+  }
+
+  bool hasMore;
+  while (NS_SUCCEEDED(senumerator->HasMore(&hasMore)) && hasMore) {
+    // From here on just skip any error we get.
+    nsAutoCString entryString;
+    if (NS_FAILED(senumerator->GetNext(entryString))) {
+      continue;
+    }
+
+    nsXPIDLCString contractID;
+    rv = categoryManager->GetCategoryEntry(aCategory, entryString.get(),
+                                           getter_Copies(contractID));
+    if (NS_FAILED(rv)) {
+      continue;
+    }
+
+    nsCOMPtr<nsISupports> instance = do_GetService(contractID);
+    if (!instance) {
+      LogMessage("While creating services from category '%s', could not create service for entry '%s', contract ID '%s'",
+                 aCategory, entryString.get(), contractID.get());
+      continue;
+    }
+
+    if (aObserverTopic) {
+      // try an observer, if it implements it.
+      nsCOMPtr<nsIObserver> observer = do_QueryInterface(instance);
+      if (observer) {
+        observer->Observe(aOrigin, aObserverTopic,
+                          aObserverData ? aObserverData : u"");
+      } else {
+        LogMessage("While creating services from category '%s', service for entry '%s', contract ID '%s' does not implement nsIObserver.",
+                   aCategory, entryString.get(), contractID.get());
+      }
+    }
+  }
+}
diff --git a/xpcom/components/nsCategoryManager.h b/xpcom/components/nsCategoryManager.h
new file mode 100644
index 000000000..3a4faed72
--- /dev/null
+++ b/xpcom/components/nsCategoryManager.h
@@ -0,0 +1,146 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+#ifndef NSCATEGORYMANAGER_H
+#define NSCATEGORYMANAGER_H
+
+#include "prio.h"
+#include "plarena.h"
+#include "nsClassHashtable.h"
+#include "nsICategoryManager.h"
+#include "nsIMemoryReporter.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/Attributes.h"
+
+class nsIMemoryReporter;
+
+/* 16d222a6-1dd2-11b2-b693-f38b02c021b2 */
+#define NS_CATEGORYMANAGER_CID \
+{ 0x16d222a6, 0x1dd2, 0x11b2, \
+  {0xb6, 0x93, 0xf3, 0x8b, 0x02, 0xc0, 0x21, 0xb2} }
+
+/**
+ * a "leaf-node", managed by the nsCategoryNode hashtable.
+ *
+ * we need to keep a "persistent value" (which will be written to the registry)
+ * and a non-persistent value (for the current runtime): these are usually
+ * the same, except when aPersist==false. The strings are permanently arena-
+ * allocated, and will never go away.
+ */
+class CategoryLeaf : public nsDepCharHashKey
+{
+public:
+  explicit CategoryLeaf(const char* aKey) : nsDepCharHashKey(aKey), value(nullptr) {}
+  const char* value;
+};
+
+
+/**
+ * CategoryNode keeps a hashtable of its entries.
+ * the CategoryNode itself is permanently allocated in
+ * the arena.
+ */
+class CategoryNode
+{
+public:
+  nsresult GetLeaf(const char* aEntryName,
+                   char** aResult);
+
+  nsresult AddLeaf(const char* aEntryName,
+                   const char* aValue,
+                   bool aReplace,
+                   char** aResult,
+                   PLArenaPool* aArena);
+
+  void DeleteLeaf(const char* aEntryName);
+
+  void Clear()
+  {
+    mozilla::MutexAutoLock lock(mLock);
+    mTable.Clear();
+  }
+
+  uint32_t Count()
+  {
+    mozilla::MutexAutoLock lock(mLock);
+    uint32_t tCount = mTable.Count();
+    return tCount;
+  }
+
+  nsresult Enumerate(nsISimpleEnumerator** aResult);
+
+  // CategoryNode is arena-allocated, with the strings
+  static CategoryNode* Create(PLArenaPool* aArena);
+  ~CategoryNode();
+  void operator delete(void*) {}
+
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf);
+
+private:
+  CategoryNode() : mLock("CategoryLeaf") {}
+
+  void* operator new(size_t aSize, PLArenaPool* aArena);
+
+  nsTHashtable<CategoryLeaf> mTable;
+  mozilla::Mutex mLock;
+};
+
+
+/**
+ * The main implementation of nsICategoryManager.
+ *
+ * This implementation is thread-safe.
+ */
+class nsCategoryManager final
+  : public nsICategoryManager
+  , public nsIMemoryReporter
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSICATEGORYMANAGER
+  NS_DECL_NSIMEMORYREPORTER
+
+  /**
+   * Suppress or unsuppress notifications of category changes to the
+   * observer service. This is to be used by nsComponentManagerImpl
+   * on startup while reading the stored category list.
+   */
+  nsresult SuppressNotifications(bool aSuppress);
+
+  void AddCategoryEntry(const char* aCategory,
+                        const char* aKey,
+                        const char* aValue,
+                        bool aReplace = true,
+                        char** aOldValue = nullptr);
+
+  static nsresult Create(nsISupports* aOuter, REFNSIID aIID, void** aResult);
+  void InitMemoryReporter();
+
+  static nsCategoryManager* GetSingleton();
+  static void Destroy();
+
+private:
+  static nsCategoryManager* gCategoryManager;
+
+  nsCategoryManager();
+  ~nsCategoryManager();
+
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf);
+
+  CategoryNode* get_category(const char* aName);
+  void NotifyObservers(const char* aTopic,
+                       const char* aCategoryName, // must be a static string
+                       const char* aEntryName);
+
+  PLArenaPool mArena;
+  nsClassHashtable<nsDepCharHashKey, CategoryNode> mTable;
+  mozilla::Mutex mLock;
+  bool mSuppressNotifications;
+};
+
+#endif
diff --git a/xpcom/components/nsCategoryManagerUtils.h b/xpcom/components/nsCategoryManagerUtils.h
new file mode 100644
index 000000000..a83d097c2
--- /dev/null
+++ b/xpcom/components/nsCategoryManagerUtils.h
@@ -0,0 +1,18 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCategoryManagerUtils_h__
+#define nsCategoryManagerUtils_h__
+
+#include "nsICategoryManager.h"
+
+void
+NS_CreateServicesFromCategory(const char* aCategory,
+                              nsISupports* aOrigin,
+                              const char* aObserverTopic,
+                              const char16_t* aObserverData = nullptr);
+
+#endif
diff --git a/xpcom/components/nsComponentManager.cpp b/xpcom/components/nsComponentManager.cpp
new file mode 100644
index 000000000..b9eb8e275
--- /dev/null
+++ b/xpcom/components/nsComponentManager.cpp
@@ -0,0 +1,2083 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This Original Code has been modified by IBM Corporation.
+ * Modifications made by IBM described herein are
+ * Copyright (c) International Business Machines
+ * Corporation, 2000
+ *
+ * Modifications to Mozilla code or documentation
+ * identified per MPL Section 3.3
+ *
+ * Date             Modified by     Description of modification
+ * 04/20/2000       IBM Corp.      Added PR_CALLBACK for Optlink use in OS2
+ */
+
+#include <stdlib.h>
+#include "nscore.h"
+#include "nsISupports.h"
+#include "nspr.h"
+#include "nsCRT.h" // for atoll
+
+// Arena used by component manager for storing contractid string, dll
+// location strings and small objects
+// CAUTION: Arena align mask needs to be defined before including plarena.h
+//          currently from nsComponentManager.h
+#define PL_ARENA_CONST_ALIGN_MASK 7
+#define NS_CM_BLOCK_SIZE (1024 * 8)
+
+#include "nsCategoryManager.h"
+#include "nsCOMPtr.h"
+#include "nsComponentManager.h"
+#include "nsDirectoryService.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsCategoryManager.h"
+#include "nsCategoryManagerUtils.h"
+#include "xptiprivate.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/XPTInterfaceInfoManager.h"
+#include "nsIConsoleService.h"
+#include "nsIObserverService.h"
+#include "nsISimpleEnumerator.h"
+#include "nsIStringEnumerator.h"
+#include "nsXPCOM.h"
+#include "nsXPCOMPrivate.h"
+#include "nsISupportsPrimitives.h"
+#include "nsIClassInfo.h"
+#include "nsLocalFile.h"
+#include "nsReadableUtils.h"
+#include "nsString.h"
+#include "nsXPIDLString.h"
+#include "prcmon.h"
+#include "xptinfo.h" // this after nsISupports, to pick up IID so that xpt stuff doesn't try to define it itself...
+#include "nsThreadUtils.h"
+#include "prthread.h"
+#include "private/pprthred.h"
+#include "nsTArray.h"
+#include "prio.h"
+#include "ManifestParser.h"
+#include "nsNetUtil.h"
+#include "mozilla/Services.h"
+
+#include "mozilla/GenericFactory.h"
+#include "nsSupportsPrimitives.h"
+#include "nsArray.h"
+#include "nsIMutableArray.h"
+#include "nsArrayEnumerator.h"
+#include "nsStringEnumerator.h"
+#include "mozilla/FileUtils.h"
+#include "mozilla/UniquePtr.h"
+#include "nsDataHashtable.h"
+
+#include <new>     // for placement new
+
+#include "mozilla/Omnijar.h"
+
+#include "mozilla/Logging.h"
+#include "LogModulePrefWatcher.h"
+
+using namespace mozilla;
+
+static LazyLogModule nsComponentManagerLog("nsComponentManager");
+
+#if 0 || defined (DEBUG_timeless)
+ #define SHOW_DENIED_ON_SHUTDOWN
+ #define SHOW_CI_ON_EXISTING_SERVICE
+#endif
+
+// Bloated registry buffer size to improve startup performance -- needs to
+// be big enough to fit the entire file into memory or it'll thrash.
+// 512K is big enough to allow for some future growth in the registry.
+#define BIG_REGISTRY_BUFLEN   (512*1024)
+
+// Common Key Names
+const char xpcomComponentsKeyName[] = "software/mozilla/XPCOM/components";
+const char xpcomKeyName[] = "software/mozilla/XPCOM";
+
+// Common Value Names
+const char fileSizeValueName[] = "FileSize";
+const char lastModValueName[] = "LastModTimeStamp";
+const char nativeComponentType[] = "application/x-mozilla-native";
+const char staticComponentType[] = "application/x-mozilla-static";
+
+NS_DEFINE_CID(kCategoryManagerCID, NS_CATEGORYMANAGER_CID);
+
+#define UID_STRING_LENGTH 39
+
+nsresult
+nsGetServiceFromCategory::operator()(const nsIID& aIID,
+                                     void** aInstancePtr) const
+{
+  nsresult rv;
+  nsXPIDLCString value;
+  nsCOMPtr<nsICategoryManager> catman;
+  nsComponentManagerImpl* compMgr = nsComponentManagerImpl::gComponentManager;
+  if (!compMgr) {
+    rv = NS_ERROR_NOT_INITIALIZED;
+    goto error;
+  }
+
+  if (!mCategory || !mEntry) {
+    // when categories have defaults, use that for null mEntry
+    rv = NS_ERROR_NULL_POINTER;
+    goto error;
+  }
+
+  rv = compMgr->nsComponentManagerImpl::GetService(kCategoryManagerCID,
+                                                   NS_GET_IID(nsICategoryManager),
+                                                   getter_AddRefs(catman));
+  if (NS_FAILED(rv)) {
+    goto error;
+  }
+
+  /* find the contractID for category.entry */
+  rv = catman->GetCategoryEntry(mCategory, mEntry,
+                                getter_Copies(value));
+  if (NS_FAILED(rv)) {
+    goto error;
+  }
+  if (!value) {
+    rv = NS_ERROR_SERVICE_NOT_AVAILABLE;
+    goto error;
+  }
+
+  rv = compMgr->nsComponentManagerImpl::GetServiceByContractID(value,
+                                                               aIID,
+                                                               aInstancePtr);
+  if (NS_FAILED(rv)) {
+error:
+    *aInstancePtr = 0;
+  }
+  if (mErrorPtr) {
+    *mErrorPtr = rv;
+  }
+  return rv;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Arena helper functions
+////////////////////////////////////////////////////////////////////////////////
+char*
+ArenaStrndup(const char* aStr, uint32_t aLen, PLArenaPool* aArena)
+{
+  void* mem;
+  // Include trailing null in the aLen
+  PL_ARENA_ALLOCATE(mem, aArena, aLen + 1);
+  if (mem) {
+    memcpy(mem, aStr, aLen + 1);
+  }
+  return static_cast<char*>(mem);
+}
+
+char*
+ArenaStrdup(const char* aStr, PLArenaPool* aArena)
+{
+  return ArenaStrndup(aStr, strlen(aStr), aArena);
+}
+
+// GetService and a few other functions need to exit their mutex mid-function
+// without reentering it later in the block. This class supports that
+// style of early-exit that MutexAutoUnlock doesn't.
+
+namespace {
+
+class MOZ_STACK_CLASS MutexLock
+{
+public:
+  explicit MutexLock(SafeMutex& aMutex)
+    : mMutex(aMutex)
+    , mLocked(false)
+  {
+    Lock();
+  }
+
+  ~MutexLock()
+  {
+    if (mLocked) {
+      Unlock();
+    }
+  }
+
+  void Lock()
+  {
+    NS_ASSERTION(!mLocked, "Re-entering a mutex");
+    mMutex.Lock();
+    mLocked = true;
+  }
+
+  void Unlock()
+  {
+    NS_ASSERTION(mLocked, "Exiting a mutex that isn't held!");
+    mMutex.Unlock();
+    mLocked = false;
+  }
+
+private:
+  SafeMutex& mMutex;
+  bool mLocked;
+};
+
+} // namespace
+
+// this is safe to call during InitXPCOM
+static already_AddRefed<nsIFile>
+GetLocationFromDirectoryService(const char* aProp)
+{
+  nsCOMPtr<nsIProperties> directoryService;
+  nsDirectoryService::Create(nullptr,
+                             NS_GET_IID(nsIProperties),
+                             getter_AddRefs(directoryService));
+
+  if (!directoryService) {
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIFile> file;
+  nsresult rv = directoryService->Get(aProp,
+                                      NS_GET_IID(nsIFile),
+                                      getter_AddRefs(file));
+  if (NS_FAILED(rv)) {
+    return nullptr;
+  }
+
+  return file.forget();
+}
+
+static already_AddRefed<nsIFile>
+CloneAndAppend(nsIFile* aBase, const nsACString& aAppend)
+{
+  nsCOMPtr<nsIFile> f;
+  aBase->Clone(getter_AddRefs(f));
+  if (!f) {
+    return nullptr;
+  }
+
+  f->AppendNative(aAppend);
+  return f.forget();
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// nsComponentManagerImpl
+////////////////////////////////////////////////////////////////////////////////
+
+nsresult
+nsComponentManagerImpl::Create(nsISupports* aOuter, REFNSIID aIID,
+                               void** aResult)
+{
+  if (aOuter) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+
+  if (!gComponentManager) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return gComponentManager->QueryInterface(aIID, aResult);
+}
+
+static const int CONTRACTID_HASHTABLE_INITIAL_LENGTH = 1024;
+
+nsComponentManagerImpl::nsComponentManagerImpl()
+  : mFactories(CONTRACTID_HASHTABLE_INITIAL_LENGTH)
+  , mContractIDs(CONTRACTID_HASHTABLE_INITIAL_LENGTH)
+  , mLock("nsComponentManagerImpl.mLock")
+  , mStatus(NOT_INITIALIZED)
+{
+}
+
+nsTArray<const mozilla::Module*>* nsComponentManagerImpl::sStaticModules;
+
+NSMODULE_DEFN(start_kPStaticModules);
+NSMODULE_DEFN(end_kPStaticModules);
+
+/* The content between start_kPStaticModules and end_kPStaticModules is gathered
+ * by the linker from various objects containing symbols in a specific section.
+ * ASAN considers (rightfully) the use of this content as a global buffer
+ * overflow. But this is a deliberate and well-considered choice, with no proper
+ * way to make ASAN happy. */
+MOZ_ASAN_BLACKLIST
+/* static */ void
+nsComponentManagerImpl::InitializeStaticModules()
+{
+  if (sStaticModules) {
+    return;
+  }
+
+  sStaticModules = new nsTArray<const mozilla::Module*>;
+  for (const mozilla::Module * const* staticModules =
+         &NSMODULE_NAME(start_kPStaticModules) + 1;
+       staticModules < &NSMODULE_NAME(end_kPStaticModules); ++staticModules)
+    if (*staticModules) { // ASAN adds padding
+      sStaticModules->AppendElement(*staticModules);
+    }
+}
+
+nsTArray<nsComponentManagerImpl::ComponentLocation>*
+nsComponentManagerImpl::sModuleLocations;
+
+/* static */ void
+nsComponentManagerImpl::InitializeModuleLocations()
+{
+  if (sModuleLocations) {
+    return;
+  }
+
+  sModuleLocations = new nsTArray<ComponentLocation>;
+}
+
+nsresult
+nsComponentManagerImpl::Init()
+{
+  MOZ_ASSERT(NOT_INITIALIZED == mStatus);
+
+  // Initialize our arena
+  PL_INIT_ARENA_POOL(&mArena, "ComponentManagerArena", NS_CM_BLOCK_SIZE);
+
+  nsCOMPtr<nsIFile> greDir =
+    GetLocationFromDirectoryService(NS_GRE_DIR);
+  nsCOMPtr<nsIFile> appDir =
+    GetLocationFromDirectoryService(NS_XPCOM_CURRENT_PROCESS_DIR);
+
+  InitializeStaticModules();
+
+  nsresult rv = mNativeModuleLoader.Init();
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  nsCategoryManager::GetSingleton()->SuppressNotifications(true);
+
+  RegisterModule(&kXPCOMModule, nullptr);
+
+  for (uint32_t i = 0; i < sStaticModules->Length(); ++i) {
+    RegisterModule((*sStaticModules)[i], nullptr);
+  }
+
+  bool loadChromeManifests = (XRE_GetProcessType() != GeckoProcessType_GPU);
+  if (loadChromeManifests) {
+    // The overall order in which chrome.manifests are expected to be treated
+    // is the following:
+    // - greDir
+    // - greDir's omni.ja
+    // - appDir
+    // - appDir's omni.ja
+
+    InitializeModuleLocations();
+    ComponentLocation* cl = sModuleLocations->AppendElement();
+    nsCOMPtr<nsIFile> lf = CloneAndAppend(greDir,
+                                          NS_LITERAL_CSTRING("chrome.manifest"));
+    cl->type = NS_APP_LOCATION;
+    cl->location.Init(lf);
+
+    RefPtr<nsZipArchive> greOmnijar =
+      mozilla::Omnijar::GetReader(mozilla::Omnijar::GRE);
+    if (greOmnijar) {
+      cl = sModuleLocations->AppendElement();
+      cl->type = NS_APP_LOCATION;
+      cl->location.Init(greOmnijar, "chrome.manifest");
+    }
+
+    bool equals = false;
+    appDir->Equals(greDir, &equals);
+    if (!equals) {
+      cl = sModuleLocations->AppendElement();
+      cl->type = NS_APP_LOCATION;
+      lf = CloneAndAppend(appDir, NS_LITERAL_CSTRING("chrome.manifest"));
+      cl->location.Init(lf);
+    }
+
+    RefPtr<nsZipArchive> appOmnijar =
+      mozilla::Omnijar::GetReader(mozilla::Omnijar::APP);
+    if (appOmnijar) {
+      cl = sModuleLocations->AppendElement();
+      cl->type = NS_APP_LOCATION;
+      cl->location.Init(appOmnijar, "chrome.manifest");
+    }
+
+    RereadChromeManifests(false);
+  }
+
+  nsCategoryManager::GetSingleton()->SuppressNotifications(false);
+
+  RegisterWeakMemoryReporter(this);
+
+  // NB: The logging preference watcher needs to be registered late enough in
+  // startup that it's okay to use the preference system, but also as soon as
+  // possible so that log modules enabled via preferences are turned on as
+  // early as possible.
+  //
+  // We can't initialize the preference watcher when the log module manager is
+  // initialized, as a number of things attempt to start logging before the
+  // preference system is initialized.
+  //
+  // The preference system is registered as a component so at this point during
+  // component manager initialization we know it is setup and we can register
+  // for notifications.
+  LogModulePrefWatcher::RegisterPrefWatcher();
+
+  // Unfortunately, we can't register the nsCategoryManager memory reporter
+  // in its constructor (which is triggered by the GetSingleton() call
+  // above) because the memory reporter manager isn't initialized at that
+  // point.  So we wait until now.
+  nsCategoryManager::GetSingleton()->InitMemoryReporter();
+
+  MOZ_LOG(nsComponentManagerLog, LogLevel::Debug,
+         ("nsComponentManager: Initialized."));
+
+  mStatus = NORMAL;
+
+  return NS_OK;
+}
+
+static bool
+ProcessSelectorMatches(Module::ProcessSelector aSelector)
+{
+  GeckoProcessType type = XRE_GetProcessType();
+  if (type == GeckoProcessType_GPU) {
+    return !!(aSelector & Module::ALLOW_IN_GPU_PROCESS);
+  }
+
+  if (aSelector & Module::MAIN_PROCESS_ONLY) {
+    return type == GeckoProcessType_Default;
+  }
+  if (aSelector & Module::CONTENT_PROCESS_ONLY) {
+    return type == GeckoProcessType_Content;
+  }
+  return true;
+}
+
+static const int kModuleVersionWithSelector = 51;
+
+void
+nsComponentManagerImpl::RegisterModule(const mozilla::Module* aModule,
+                                       FileLocation* aFile)
+{
+  mLock.AssertNotCurrentThreadOwns();
+
+  if (aModule->mVersion >= kModuleVersionWithSelector &&
+      !ProcessSelectorMatches(aModule->selector))
+  {
+    return;
+  }
+
+  {
+    // Scope the monitor so that we don't hold it while calling into the
+    // category manager.
+    MutexLock lock(mLock);
+
+    KnownModule* m;
+    if (aFile) {
+      nsCString uri;
+      aFile->GetURIString(uri);
+      NS_ASSERTION(!mKnownModules.Get(uri),
+                   "Must not register a binary module twice.");
+
+      m = new KnownModule(aModule, *aFile);
+      mKnownModules.Put(uri, m);
+    } else {
+      m = new KnownModule(aModule);
+      mKnownStaticModules.AppendElement(m);
+    }
+
+    if (aModule->mCIDs) {
+      const mozilla::Module::CIDEntry* entry;
+      for (entry = aModule->mCIDs; entry->cid; ++entry) {
+        RegisterCIDEntryLocked(entry, m);
+      }
+    }
+
+    if (aModule->mContractIDs) {
+      const mozilla::Module::ContractIDEntry* entry;
+      for (entry = aModule->mContractIDs; entry->contractid; ++entry) {
+        RegisterContractIDLocked(entry);
+      }
+      MOZ_ASSERT(!entry->cid, "Incorrectly terminated contract list");
+    }
+  }
+
+  if (aModule->mCategoryEntries) {
+    const mozilla::Module::CategoryEntry* entry;
+    for (entry = aModule->mCategoryEntries; entry->category; ++entry)
+      nsCategoryManager::GetSingleton()->AddCategoryEntry(entry->category,
+                                                          entry->entry,
+                                                          entry->value);
+  }
+}
+
+void
+nsComponentManagerImpl::RegisterCIDEntryLocked(
+    const mozilla::Module::CIDEntry* aEntry,
+    KnownModule* aModule)
+{
+  mLock.AssertCurrentThreadOwns();
+
+  if (!ProcessSelectorMatches(aEntry->processSelector)) {
+    return;
+  }
+
+  nsFactoryEntry* f = mFactories.Get(*aEntry->cid);
+  if (f) {
+    NS_WARNING("Re-registering a CID?");
+
+    char idstr[NSID_LENGTH];
+    aEntry->cid->ToProvidedString(idstr);
+
+    nsCString existing;
+    if (f->mModule) {
+      existing = f->mModule->Description();
+    } else {
+      existing = "<unknown module>";
+    }
+    SafeMutexAutoUnlock unlock(mLock);
+    LogMessage("While registering XPCOM module %s, trying to re-register CID '%s' already registered by %s.",
+               aModule->Description().get(),
+               idstr,
+               existing.get());
+    return;
+  }
+
+  f = new nsFactoryEntry(aEntry, aModule);
+  mFactories.Put(*aEntry->cid, f);
+}
+
+void
+nsComponentManagerImpl::RegisterContractIDLocked(
+    const mozilla::Module::ContractIDEntry* aEntry)
+{
+  mLock.AssertCurrentThreadOwns();
+
+  if (!ProcessSelectorMatches(aEntry->processSelector)) {
+    return;
+  }
+
+  nsFactoryEntry* f = mFactories.Get(*aEntry->cid);
+  if (!f) {
+    NS_WARNING("No CID found when attempting to map contract ID");
+
+    char idstr[NSID_LENGTH];
+    aEntry->cid->ToProvidedString(idstr);
+
+    SafeMutexAutoUnlock unlock(mLock);
+    LogMessage("Could not map contract ID '%s' to CID %s because no implementation of the CID is registered.",
+               aEntry->contractid,
+               idstr);
+
+    return;
+  }
+
+  mContractIDs.Put(nsDependentCString(aEntry->contractid), f);
+}
+
+static void
+CutExtension(nsCString& aPath)
+{
+  int32_t dotPos = aPath.RFindChar('.');
+  if (kNotFound == dotPos) {
+    aPath.Truncate();
+  } else {
+    aPath.Cut(0, dotPos + 1);
+  }
+}
+
+static void
+DoRegisterManifest(NSLocationType aType,
+                   FileLocation& aFile,
+                   bool aChromeOnly,
+                   bool aXPTOnly)
+{
+  MOZ_ASSERT(!aXPTOnly || !nsComponentManagerImpl::gComponentManager);
+  uint32_t len;
+  FileLocation::Data data;
+  UniquePtr<char[]> buf;
+  nsresult rv = aFile.GetData(data);
+  if (NS_SUCCEEDED(rv)) {
+    rv = data.GetSize(&len);
+  }
+  if (NS_SUCCEEDED(rv)) {
+    buf = MakeUnique<char[]>(len + 1);
+    rv = data.Copy(buf.get(), len);
+  }
+  if (NS_SUCCEEDED(rv)) {
+    buf[len] = '\0';
+    ParseManifest(aType, aFile, buf.get(), aChromeOnly, aXPTOnly);
+  } else if (NS_BOOTSTRAPPED_LOCATION != aType) {
+    nsCString uri;
+    aFile.GetURIString(uri);
+    LogMessage("Could not read chrome manifest '%s'.", uri.get());
+  }
+}
+
+void
+nsComponentManagerImpl::RegisterManifest(NSLocationType aType,
+                                         FileLocation& aFile,
+                                         bool aChromeOnly)
+{
+  DoRegisterManifest(aType, aFile, aChromeOnly, false);
+}
+
+void
+nsComponentManagerImpl::ManifestManifest(ManifestProcessingContext& aCx,
+                                         int aLineNo, char* const* aArgv)
+{
+  char* file = aArgv[0];
+  FileLocation f(aCx.mFile, file);
+  RegisterManifest(aCx.mType, f, aCx.mChromeOnly);
+}
+
+void
+nsComponentManagerImpl::ManifestBinaryComponent(ManifestProcessingContext& aCx,
+                                                int aLineNo,
+                                                char* const* aArgv)
+{
+  if (aCx.mFile.IsZip()) {
+    NS_WARNING("Cannot load binary components from a jar.");
+    LogMessageWithContext(aCx.mFile, aLineNo,
+                          "Cannot load binary components from a jar.");
+    return;
+  }
+
+  FileLocation f(aCx.mFile, aArgv[0]);
+  nsCString uri;
+  f.GetURIString(uri);
+
+  if (mKnownModules.Get(uri)) {
+    NS_WARNING("Attempting to register a binary component twice.");
+    LogMessageWithContext(aCx.mFile, aLineNo,
+                          "Attempting to register a binary component twice.");
+    return;
+  }
+
+  const mozilla::Module* m = mNativeModuleLoader.LoadModule(f);
+  // The native module loader should report an error here, we don't have to
+  if (!m) {
+    return;
+  }
+
+  RegisterModule(m, &f);
+}
+
+static void
+DoRegisterXPT(FileLocation& aFile)
+{
+  uint32_t len;
+  FileLocation::Data data;
+  UniquePtr<char[]> buf;
+  nsresult rv = aFile.GetData(data);
+  if (NS_SUCCEEDED(rv)) {
+    rv = data.GetSize(&len);
+  }
+  if (NS_SUCCEEDED(rv)) {
+    buf = MakeUnique<char[]>(len);
+    rv = data.Copy(buf.get(), len);
+  }
+  if (NS_SUCCEEDED(rv)) {
+    XPTInterfaceInfoManager::GetSingleton()->RegisterBuffer(buf.get(), len);
+  } else {
+    nsCString uri;
+    aFile.GetURIString(uri);
+    LogMessage("Could not read '%s'.", uri.get());
+  }
+}
+
+void
+nsComponentManagerImpl::ManifestXPT(ManifestProcessingContext& aCx,
+                                    int aLineNo, char* const* aArgv)
+{
+  FileLocation f(aCx.mFile, aArgv[0]);
+  DoRegisterXPT(f);
+}
+
+void
+nsComponentManagerImpl::ManifestComponent(ManifestProcessingContext& aCx,
+                                          int aLineNo, char* const* aArgv)
+{
+  mLock.AssertNotCurrentThreadOwns();
+
+  char* id = aArgv[0];
+  char* file = aArgv[1];
+
+  nsID cid;
+  if (!cid.Parse(id)) {
+    LogMessageWithContext(aCx.mFile, aLineNo,
+                          "Malformed CID: '%s'.", id);
+    return;
+  }
+
+  // Precompute the hash/file data outside of the lock
+  FileLocation fl(aCx.mFile, file);
+  nsCString hash;
+  fl.GetURIString(hash);
+
+  MutexLock lock(mLock);
+  nsFactoryEntry* f = mFactories.Get(cid);
+  if (f) {
+    char idstr[NSID_LENGTH];
+    cid.ToProvidedString(idstr);
+
+    nsCString existing;
+    if (f->mModule) {
+      existing = f->mModule->Description();
+    } else {
+      existing = "<unknown module>";
+    }
+
+    lock.Unlock();
+
+    LogMessageWithContext(aCx.mFile, aLineNo,
+                          "Trying to re-register CID '%s' already registered by %s.",
+                          idstr,
+                          existing.get());
+    return;
+  }
+
+  KnownModule* km;
+
+  km = mKnownModules.Get(hash);
+  if (!km) {
+    km = new KnownModule(fl);
+    mKnownModules.Put(hash, km);
+  }
+
+  void* place;
+
+  PL_ARENA_ALLOCATE(place, &mArena, sizeof(nsCID));
+  nsID* permanentCID = static_cast<nsID*>(place);
+  *permanentCID = cid;
+
+  PL_ARENA_ALLOCATE(place, &mArena, sizeof(mozilla::Module::CIDEntry));
+  mozilla::Module::CIDEntry* e = new (place) mozilla::Module::CIDEntry();
+  e->cid = permanentCID;
+
+  f = new nsFactoryEntry(e, km);
+  mFactories.Put(cid, f);
+}
+
+void
+nsComponentManagerImpl::ManifestContract(ManifestProcessingContext& aCx,
+                                         int aLineNo, char* const* aArgv)
+{
+  mLock.AssertNotCurrentThreadOwns();
+
+  char* contract = aArgv[0];
+  char* id = aArgv[1];
+
+  nsID cid;
+  if (!cid.Parse(id)) {
+    LogMessageWithContext(aCx.mFile, aLineNo,
+                          "Malformed CID: '%s'.", id);
+    return;
+  }
+
+  MutexLock lock(mLock);
+  nsFactoryEntry* f = mFactories.Get(cid);
+  if (!f) {
+    lock.Unlock();
+    LogMessageWithContext(aCx.mFile, aLineNo,
+                          "Could not map contract ID '%s' to CID %s because no implementation of the CID is registered.",
+                          contract, id);
+    return;
+  }
+
+  mContractIDs.Put(nsDependentCString(contract), f);
+}
+
+void
+nsComponentManagerImpl::ManifestCategory(ManifestProcessingContext& aCx,
+                                         int aLineNo, char* const* aArgv)
+{
+  char* category = aArgv[0];
+  char* key = aArgv[1];
+  char* value = aArgv[2];
+
+  nsCategoryManager::GetSingleton()->
+  AddCategoryEntry(category, key, value);
+}
+
+void
+nsComponentManagerImpl::RereadChromeManifests(bool aChromeOnly)
+{
+  for (uint32_t i = 0; i < sModuleLocations->Length(); ++i) {
+    ComponentLocation& l = sModuleLocations->ElementAt(i);
+    RegisterManifest(l.type, l.location, aChromeOnly);
+  }
+}
+
+bool
+nsComponentManagerImpl::KnownModule::EnsureLoader()
+{
+  if (!mLoader) {
+    nsCString extension;
+    mFile.GetURIString(extension);
+    CutExtension(extension);
+    mLoader =
+      nsComponentManagerImpl::gComponentManager->LoaderForExtension(extension);
+  }
+  return !!mLoader;
+}
+
+bool
+nsComponentManagerImpl::KnownModule::Load()
+{
+  if (mFailed) {
+    return false;
+  }
+  if (!mModule) {
+    if (!EnsureLoader()) {
+      return false;
+    }
+
+    mModule = mLoader->LoadModule(mFile);
+
+    if (!mModule) {
+      mFailed = true;
+      return false;
+    }
+  }
+  if (!mLoaded) {
+    if (mModule->loadProc) {
+      nsresult rv = mModule->loadProc();
+      if (NS_FAILED(rv)) {
+        mFailed = true;
+        return false;
+      }
+    }
+    mLoaded = true;
+  }
+  return true;
+}
+
+nsCString
+nsComponentManagerImpl::KnownModule::Description() const
+{
+  nsCString s;
+  if (mFile) {
+    mFile.GetURIString(s);
+  } else {
+    s = "<static module>";
+  }
+  return s;
+}
+
+nsresult nsComponentManagerImpl::Shutdown(void)
+{
+  MOZ_ASSERT(NORMAL == mStatus);
+
+  mStatus = SHUTDOWN_IN_PROGRESS;
+
+  // Shutdown the component manager
+  MOZ_LOG(nsComponentManagerLog, LogLevel::Debug,
+         ("nsComponentManager: Beginning Shutdown."));
+
+  UnregisterWeakMemoryReporter(this);
+
+  // Release all cached factories
+  mContractIDs.Clear();
+  mFactories.Clear(); // XXX release the objects, don't just clear
+  mLoaderMap.Clear();
+  mKnownModules.Clear();
+  mKnownStaticModules.Clear();
+
+  delete sStaticModules;
+  delete sModuleLocations;
+
+  // Unload libraries
+  mNativeModuleLoader.UnloadLibraries();
+
+  // delete arena for strings and small objects
+  PL_FinishArenaPool(&mArena);
+
+  mStatus = SHUTDOWN_COMPLETE;
+
+  MOZ_LOG(nsComponentManagerLog, LogLevel::Debug,
+         ("nsComponentManager: Shutdown complete."));
+
+  return NS_OK;
+}
+
+nsComponentManagerImpl::~nsComponentManagerImpl()
+{
+  MOZ_LOG(nsComponentManagerLog, LogLevel::Debug,
+         ("nsComponentManager: Beginning destruction."));
+
+  if (SHUTDOWN_COMPLETE != mStatus) {
+    Shutdown();
+  }
+
+  MOZ_LOG(nsComponentManagerLog, LogLevel::Debug,
+         ("nsComponentManager: Destroyed."));
+}
+
+NS_IMPL_ISUPPORTS(nsComponentManagerImpl,
+                  nsIComponentManager,
+                  nsIServiceManager,
+                  nsIComponentRegistrar,
+                  nsISupportsWeakReference,
+                  nsIInterfaceRequestor,
+                  nsIMemoryReporter)
+
+nsresult
+nsComponentManagerImpl::GetInterface(const nsIID& aUuid, void** aResult)
+{
+  NS_WARNING("This isn't supported");
+  // fall through to QI as anything QIable is a superset of what can be
+  // got via the GetInterface()
+  return  QueryInterface(aUuid, aResult);
+}
+
+nsFactoryEntry*
+nsComponentManagerImpl::GetFactoryEntry(const char* aContractID,
+                                        uint32_t aContractIDLen)
+{
+  SafeMutexAutoLock lock(mLock);
+  return mContractIDs.Get(nsDependentCString(aContractID, aContractIDLen));
+}
+
+
+nsFactoryEntry*
+nsComponentManagerImpl::GetFactoryEntry(const nsCID& aClass)
+{
+  SafeMutexAutoLock lock(mLock);
+  return mFactories.Get(aClass);
+}
+
+already_AddRefed<nsIFactory>
+nsComponentManagerImpl::FindFactory(const nsCID& aClass)
+{
+  nsFactoryEntry* e = GetFactoryEntry(aClass);
+  if (!e) {
+    return nullptr;
+  }
+
+  return e->GetFactory();
+}
+
+already_AddRefed<nsIFactory>
+nsComponentManagerImpl::FindFactory(const char* aContractID,
+                                    uint32_t aContractIDLen)
+{
+  nsFactoryEntry* entry = GetFactoryEntry(aContractID, aContractIDLen);
+  if (!entry) {
+    return nullptr;
+  }
+
+  return entry->GetFactory();
+}
+
+/**
+ * GetClassObject()
+ *
+ * Given a classID, this finds the singleton ClassObject that implements the CID.
+ * Returns an interface of type aIID off the singleton classobject.
+ */
+NS_IMETHODIMP
+nsComponentManagerImpl::GetClassObject(const nsCID& aClass, const nsIID& aIID,
+                                       void** aResult)
+{
+  nsresult rv;
+
+  if (MOZ_LOG_TEST(nsComponentManagerLog, LogLevel::Debug)) {
+    char* buf = aClass.ToString();
+    PR_LogPrint("nsComponentManager: GetClassObject(%s)", buf);
+    if (buf) {
+      free(buf);
+    }
+  }
+
+  MOZ_ASSERT(aResult != nullptr);
+
+  nsCOMPtr<nsIFactory> factory = FindFactory(aClass);
+  if (!factory) {
+    return NS_ERROR_FACTORY_NOT_REGISTERED;
+  }
+
+  rv = factory->QueryInterface(aIID, aResult);
+
+  MOZ_LOG(nsComponentManagerLog, LogLevel::Warning,
+         ("\t\tGetClassObject() %s", NS_SUCCEEDED(rv) ? "succeeded" : "FAILED"));
+
+  return rv;
+}
+
+
+NS_IMETHODIMP
+nsComponentManagerImpl::GetClassObjectByContractID(const char* aContractID,
+                                                   const nsIID& aIID,
+                                                   void** aResult)
+{
+  if (NS_WARN_IF(!aResult) ||
+      NS_WARN_IF(!aContractID)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsresult rv;
+
+  MOZ_LOG(nsComponentManagerLog, LogLevel::Debug,
+         ("nsComponentManager: GetClassObject(%s)", aContractID));
+
+  nsCOMPtr<nsIFactory> factory = FindFactory(aContractID, strlen(aContractID));
+  if (!factory) {
+    return NS_ERROR_FACTORY_NOT_REGISTERED;
+  }
+
+  rv = factory->QueryInterface(aIID, aResult);
+
+  MOZ_LOG(nsComponentManagerLog, LogLevel::Warning,
+         ("\t\tGetClassObject() %s", NS_SUCCEEDED(rv) ? "succeeded" : "FAILED"));
+
+  return rv;
+}
+
+/**
+ * CreateInstance()
+ *
+ * Create an instance of an object that implements an interface and belongs
+ * to the implementation aClass using the factory. The factory is immediately
+ * released and not held onto for any longer.
+ */
+NS_IMETHODIMP
+nsComponentManagerImpl::CreateInstance(const nsCID& aClass,
+                                       nsISupports* aDelegate,
+                                       const nsIID& aIID,
+                                       void** aResult)
+{
+  // test this first, since there's no point in creating a component during
+  // shutdown -- whether it's available or not would depend on the order it
+  // occurs in the list
+  if (gXPCOMShuttingDown) {
+    // When processing shutdown, don't process new GetService() requests
+#ifdef SHOW_DENIED_ON_SHUTDOWN
+    nsXPIDLCString cid, iid;
+    cid.Adopt(aClass.ToString());
+    iid.Adopt(aIID.ToString());
+    fprintf(stderr, "Creating new instance on shutdown. Denied.\n"
+            "         CID: %s\n         IID: %s\n", cid.get(), iid.get());
+#endif /* SHOW_DENIED_ON_SHUTDOWN */
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+  *aResult = nullptr;
+
+  nsFactoryEntry* entry = GetFactoryEntry(aClass);
+
+  if (!entry) {
+    return NS_ERROR_FACTORY_NOT_REGISTERED;
+  }
+
+#ifdef SHOW_CI_ON_EXISTING_SERVICE
+  if (entry->mServiceObject) {
+    nsXPIDLCString cid;
+    cid.Adopt(aClass.ToString());
+    nsAutoCString message;
+    message = NS_LITERAL_CSTRING("You are calling CreateInstance \"") +
+              cid +
+              NS_LITERAL_CSTRING("\" when a service for this CID already exists!");
+    NS_ERROR(message.get());
+  }
+#endif
+
+  nsresult rv;
+  nsCOMPtr<nsIFactory> factory = entry->GetFactory();
+  if (factory) {
+    rv = factory->CreateInstance(aDelegate, aIID, aResult);
+    if (NS_SUCCEEDED(rv) && !*aResult) {
+      NS_ERROR("Factory did not return an object but returned success!");
+      rv = NS_ERROR_SERVICE_NOT_FOUND;
+    }
+  } else {
+    // Translate error values
+    rv = NS_ERROR_FACTORY_NOT_REGISTERED;
+  }
+
+  if (MOZ_LOG_TEST(nsComponentManagerLog, LogLevel::Warning)) {
+    char* buf = aClass.ToString();
+    MOZ_LOG(nsComponentManagerLog, LogLevel::Warning,
+           ("nsComponentManager: CreateInstance(%s) %s", buf,
+            NS_SUCCEEDED(rv) ? "succeeded" : "FAILED"));
+    if (buf) {
+      free(buf);
+    }
+  }
+
+  return rv;
+}
+
+/**
+ * CreateInstanceByContractID()
+ *
+ * A variant of CreateInstance() that creates an instance of the object that
+ * implements the interface aIID and whose implementation has a contractID aContractID.
+ *
+ * This is only a convenience routine that turns around can calls the
+ * CreateInstance() with classid and iid.
+ */
+NS_IMETHODIMP
+nsComponentManagerImpl::CreateInstanceByContractID(const char* aContractID,
+                                                   nsISupports* aDelegate,
+                                                   const nsIID& aIID,
+                                                   void** aResult)
+{
+  if (NS_WARN_IF(!aContractID)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // test this first, since there's no point in creating a component during
+  // shutdown -- whether it's available or not would depend on the order it
+  // occurs in the list
+  if (gXPCOMShuttingDown) {
+    // When processing shutdown, don't process new GetService() requests
+#ifdef SHOW_DENIED_ON_SHUTDOWN
+    nsXPIDLCString iid;
+    iid.Adopt(aIID.ToString());
+    fprintf(stderr, "Creating new instance on shutdown. Denied.\n"
+            "  ContractID: %s\n         IID: %s\n", aContractID, iid.get());
+#endif /* SHOW_DENIED_ON_SHUTDOWN */
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+  *aResult = nullptr;
+
+  nsFactoryEntry* entry = GetFactoryEntry(aContractID, strlen(aContractID));
+
+  if (!entry) {
+    return NS_ERROR_FACTORY_NOT_REGISTERED;
+  }
+
+#ifdef SHOW_CI_ON_EXISTING_SERVICE
+  if (entry->mServiceObject) {
+    nsAutoCString message;
+    message =
+      NS_LITERAL_CSTRING("You are calling CreateInstance \"") +
+      nsDependentCString(aContractID) +
+      NS_LITERAL_CSTRING("\" when a service for this CID already exists! "
+                         "Add it to abusedContracts to track down the service consumer.");
+    NS_ERROR(message.get());
+  }
+#endif
+
+  nsresult rv;
+  nsCOMPtr<nsIFactory> factory = entry->GetFactory();
+  if (factory) {
+
+    rv = factory->CreateInstance(aDelegate, aIID, aResult);
+    if (NS_SUCCEEDED(rv) && !*aResult) {
+      NS_ERROR("Factory did not return an object but returned success!");
+      rv = NS_ERROR_SERVICE_NOT_FOUND;
+    }
+  } else {
+    // Translate error values
+    rv = NS_ERROR_FACTORY_NOT_REGISTERED;
+  }
+
+  MOZ_LOG(nsComponentManagerLog, LogLevel::Warning,
+         ("nsComponentManager: CreateInstanceByContractID(%s) %s", aContractID,
+          NS_SUCCEEDED(rv) ? "succeeded" : "FAILED"));
+
+  return rv;
+}
+
+nsresult
+nsComponentManagerImpl::FreeServices()
+{
+  NS_ASSERTION(gXPCOMShuttingDown,
+               "Must be shutting down in order to free all services");
+
+  if (!gXPCOMShuttingDown) {
+    return NS_ERROR_FAILURE;
+  }
+
+  for (auto iter = mFactories.Iter(); !iter.Done(); iter.Next()) {
+    nsFactoryEntry* entry = iter.UserData();
+    entry->mFactory = nullptr;
+    entry->mServiceObject = nullptr;
+  }
+
+  return NS_OK;
+}
+
+// This should only ever be called within the monitor!
+nsComponentManagerImpl::PendingServiceInfo*
+nsComponentManagerImpl::AddPendingService(const nsCID& aServiceCID,
+                                          PRThread* aThread)
+{
+  PendingServiceInfo* newInfo = mPendingServices.AppendElement();
+  if (newInfo) {
+    newInfo->cid = &aServiceCID;
+    newInfo->thread = aThread;
+  }
+  return newInfo;
+}
+
+// This should only ever be called within the monitor!
+void
+nsComponentManagerImpl::RemovePendingService(const nsCID& aServiceCID)
+{
+  uint32_t pendingCount = mPendingServices.Length();
+  for (uint32_t index = 0; index < pendingCount; ++index) {
+    const PendingServiceInfo& info = mPendingServices.ElementAt(index);
+    if (info.cid->Equals(aServiceCID)) {
+      mPendingServices.RemoveElementAt(index);
+      return;
+    }
+  }
+}
+
+// This should only ever be called within the monitor!
+PRThread*
+nsComponentManagerImpl::GetPendingServiceThread(const nsCID& aServiceCID) const
+{
+  uint32_t pendingCount = mPendingServices.Length();
+  for (uint32_t index = 0; index < pendingCount; ++index) {
+    const PendingServiceInfo& info = mPendingServices.ElementAt(index);
+    if (info.cid->Equals(aServiceCID)) {
+      return info.thread;
+    }
+  }
+  return nullptr;
+}
+
+NS_IMETHODIMP
+nsComponentManagerImpl::GetService(const nsCID& aClass,
+                                   const nsIID& aIID,
+                                   void** aResult)
+{
+  // test this first, since there's no point in returning a service during
+  // shutdown -- whether it's available or not would depend on the order it
+  // occurs in the list
+  if (gXPCOMShuttingDown) {
+    // When processing shutdown, don't process new GetService() requests
+#ifdef SHOW_DENIED_ON_SHUTDOWN
+    nsXPIDLCString cid, iid;
+    cid.Adopt(aClass.ToString());
+    iid.Adopt(aIID.ToString());
+    fprintf(stderr, "Getting service on shutdown. Denied.\n"
+            "         CID: %s\n         IID: %s\n", cid.get(), iid.get());
+#endif /* SHOW_DENIED_ON_SHUTDOWN */
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  // `service` must be released after the lock is released, so it must be
+  // declared before the lock in this C++ block.
+  nsCOMPtr<nsISupports> service;
+  MutexLock lock(mLock);
+
+  nsFactoryEntry* entry = mFactories.Get(aClass);
+  if (!entry) {
+    return NS_ERROR_FACTORY_NOT_REGISTERED;
+  }
+
+  if (entry->mServiceObject) {
+    lock.Unlock();
+    return entry->mServiceObject->QueryInterface(aIID, aResult);
+  }
+
+  PRThread* currentPRThread = PR_GetCurrentThread();
+  MOZ_ASSERT(currentPRThread, "This should never be null!");
+
+  // Needed to optimize the event loop below.
+  nsIThread* currentThread = nullptr;
+
+  PRThread* pendingPRThread;
+  while ((pendingPRThread = GetPendingServiceThread(aClass))) {
+    if (pendingPRThread == currentPRThread) {
+      NS_ERROR("Recursive GetService!");
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+
+
+    SafeMutexAutoUnlock unlockPending(mLock);
+
+    if (!currentThread) {
+      currentThread = NS_GetCurrentThread();
+      MOZ_ASSERT(currentThread, "This should never be null!");
+    }
+
+    // This will process a single event or yield the thread if no event is
+    // pending.
+    if (!NS_ProcessNextEvent(currentThread, false)) {
+      PR_Sleep(PR_INTERVAL_NO_WAIT);
+    }
+  }
+
+  // It's still possible that the other thread failed to create the
+  // service so we're not guaranteed to have an entry or service yet.
+  if (entry->mServiceObject) {
+    lock.Unlock();
+    return entry->mServiceObject->QueryInterface(aIID, aResult);
+  }
+
+#ifdef DEBUG
+  PendingServiceInfo* newInfo =
+#endif
+    AddPendingService(aClass, currentPRThread);
+  NS_ASSERTION(newInfo, "Failed to add info to the array!");
+
+  // We need to not be holding the service manager's lock while calling
+  // CreateInstance, because it invokes user code which could try to re-enter
+  // the service manager:
+
+  nsresult rv;
+  {
+    SafeMutexAutoUnlock unlock(mLock);
+    rv = CreateInstance(aClass, nullptr, aIID, getter_AddRefs(service));
+  }
+  if (NS_SUCCEEDED(rv) && !service) {
+    NS_ERROR("Factory did not return an object but returned success");
+    return NS_ERROR_SERVICE_NOT_FOUND;
+  }
+
+#ifdef DEBUG
+  pendingPRThread = GetPendingServiceThread(aClass);
+  MOZ_ASSERT(pendingPRThread == currentPRThread,
+             "Pending service array has been changed!");
+#endif
+  RemovePendingService(aClass);
+
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  NS_ASSERTION(!entry->mServiceObject, "Created two instances of a service!");
+
+  entry->mServiceObject = service.forget();
+
+  lock.Unlock();
+  nsISupports** sresult = reinterpret_cast<nsISupports**>(aResult);
+  *sresult = entry->mServiceObject;
+  (*sresult)->AddRef();
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsComponentManagerImpl::IsServiceInstantiated(const nsCID& aClass,
+                                              const nsIID& aIID,
+                                              bool* aResult)
+{
+  // Now we want to get the service if we already got it. If not, we don't want
+  // to create an instance of it. mmh!
+
+  // test this first, since there's no point in returning a service during
+  // shutdown -- whether it's available or not would depend on the order it
+  // occurs in the list
+  if (gXPCOMShuttingDown) {
+    // When processing shutdown, don't process new GetService() requests
+#ifdef SHOW_DENIED_ON_SHUTDOWN
+    nsXPIDLCString cid, iid;
+    cid.Adopt(aClass.ToString());
+    iid.Adopt(aIID.ToString());
+    fprintf(stderr, "Checking for service on shutdown. Denied.\n"
+            "         CID: %s\n         IID: %s\n", cid.get(), iid.get());
+#endif /* SHOW_DENIED_ON_SHUTDOWN */
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  nsresult rv = NS_ERROR_SERVICE_NOT_AVAILABLE;
+  nsFactoryEntry* entry;
+
+  {
+    SafeMutexAutoLock lock(mLock);
+    entry = mFactories.Get(aClass);
+  }
+
+  if (entry && entry->mServiceObject) {
+    nsCOMPtr<nsISupports> service;
+    rv = entry->mServiceObject->QueryInterface(aIID, getter_AddRefs(service));
+    *aResult = (service != nullptr);
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsComponentManagerImpl::IsServiceInstantiatedByContractID(
+    const char* aContractID,
+    const nsIID& aIID,
+    bool* aResult)
+{
+  // Now we want to get the service if we already got it. If not, we don't want
+  // to create an instance of it. mmh!
+
+  // test this first, since there's no point in returning a service during
+  // shutdown -- whether it's available or not would depend on the order it
+  // occurs in the list
+  if (gXPCOMShuttingDown) {
+    // When processing shutdown, don't process new GetService() requests
+#ifdef SHOW_DENIED_ON_SHUTDOWN
+    nsXPIDLCString iid;
+    iid.Adopt(aIID.ToString());
+    fprintf(stderr, "Checking for service on shutdown. Denied.\n"
+            "  ContractID: %s\n         IID: %s\n", aContractID, iid.get());
+#endif /* SHOW_DENIED_ON_SHUTDOWN */
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  nsresult rv = NS_ERROR_SERVICE_NOT_AVAILABLE;
+  nsFactoryEntry* entry;
+  {
+    SafeMutexAutoLock lock(mLock);
+    entry = mContractIDs.Get(nsDependentCString(aContractID));
+  }
+
+  if (entry && entry->mServiceObject) {
+    nsCOMPtr<nsISupports> service;
+    rv = entry->mServiceObject->QueryInterface(aIID, getter_AddRefs(service));
+    *aResult = (service != nullptr);
+  }
+  return rv;
+}
+
+
+NS_IMETHODIMP
+nsComponentManagerImpl::GetServiceByContractID(const char* aContractID,
+                                               const nsIID& aIID,
+                                               void** aResult)
+{
+  // test this first, since there's no point in returning a service during
+  // shutdown -- whether it's available or not would depend on the order it
+  // occurs in the list
+  if (gXPCOMShuttingDown) {
+    // When processing shutdown, don't process new GetService() requests
+#ifdef SHOW_DENIED_ON_SHUTDOWN
+    nsXPIDLCString iid;
+    iid.Adopt(aIID.ToString());
+    fprintf(stderr, "Getting service on shutdown. Denied.\n"
+            "  ContractID: %s\n         IID: %s\n", aContractID, iid.get());
+#endif /* SHOW_DENIED_ON_SHUTDOWN */
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  // `service` must be released after the lock is released, so it must be
+  // declared before the lock in this C++ block.
+  nsCOMPtr<nsISupports> service;
+  MutexLock lock(mLock);
+
+  nsFactoryEntry* entry = mContractIDs.Get(nsDependentCString(aContractID));
+  if (!entry) {
+    return NS_ERROR_FACTORY_NOT_REGISTERED;
+  }
+
+  if (entry->mServiceObject) {
+    // We need to not be holding the service manager's monitor while calling
+    // QueryInterface, because it invokes user code which could try to re-enter
+    // the service manager, or try to grab some other lock/monitor/condvar
+    // and deadlock, e.g. bug 282743.
+    // `entry` is valid until XPCOM shutdown, so we can safely use it after
+    // exiting the lock.
+    lock.Unlock();
+    return entry->mServiceObject->QueryInterface(aIID, aResult);
+  }
+
+  PRThread* currentPRThread = PR_GetCurrentThread();
+  MOZ_ASSERT(currentPRThread, "This should never be null!");
+
+  // Needed to optimize the event loop below.
+  nsIThread* currentThread = nullptr;
+
+  PRThread* pendingPRThread;
+  while ((pendingPRThread = GetPendingServiceThread(*entry->mCIDEntry->cid))) {
+    if (pendingPRThread == currentPRThread) {
+      NS_ERROR("Recursive GetService!");
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+
+    SafeMutexAutoUnlock unlockPending(mLock);
+
+    if (!currentThread) {
+      currentThread = NS_GetCurrentThread();
+      MOZ_ASSERT(currentThread, "This should never be null!");
+    }
+
+    // This will process a single event or yield the thread if no event is
+    // pending.
+    if (!NS_ProcessNextEvent(currentThread, false)) {
+      PR_Sleep(PR_INTERVAL_NO_WAIT);
+    }
+  }
+
+  if (currentThread && entry->mServiceObject) {
+    // If we have a currentThread then we must have waited on another thread
+    // to create the service. Grab it now if that succeeded.
+    lock.Unlock();
+    return entry->mServiceObject->QueryInterface(aIID, aResult);
+  }
+
+#ifdef DEBUG
+  PendingServiceInfo* newInfo =
+#endif
+    AddPendingService(*entry->mCIDEntry->cid, currentPRThread);
+  NS_ASSERTION(newInfo, "Failed to add info to the array!");
+
+  // We need to not be holding the service manager's lock while calling
+  // CreateInstance, because it invokes user code which could try to re-enter
+  // the service manager:
+
+  nsresult rv;
+  {
+    SafeMutexAutoUnlock unlock(mLock);
+    rv = CreateInstanceByContractID(aContractID, nullptr, aIID,
+                                    getter_AddRefs(service));
+  }
+  if (NS_SUCCEEDED(rv) && !service) {
+    NS_ERROR("Factory did not return an object but returned success");
+    return NS_ERROR_SERVICE_NOT_FOUND;
+  }
+
+#ifdef DEBUG
+  pendingPRThread = GetPendingServiceThread(*entry->mCIDEntry->cid);
+  MOZ_ASSERT(pendingPRThread == currentPRThread,
+             "Pending service array has been changed!");
+#endif
+  RemovePendingService(*entry->mCIDEntry->cid);
+
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  NS_ASSERTION(!entry->mServiceObject, "Created two instances of a service!");
+
+  entry->mServiceObject = service.forget();
+
+  lock.Unlock();
+
+  nsISupports** sresult = reinterpret_cast<nsISupports**>(aResult);
+  *sresult = entry->mServiceObject;
+  (*sresult)->AddRef();
+
+  return NS_OK;
+}
+
+already_AddRefed<mozilla::ModuleLoader>
+nsComponentManagerImpl::LoaderForExtension(const nsACString& aExt)
+{
+  nsCOMPtr<mozilla::ModuleLoader> loader = mLoaderMap.Get(aExt);
+  if (!loader) {
+    loader = do_GetServiceFromCategory("module-loader",
+                                       PromiseFlatCString(aExt).get());
+    if (!loader) {
+      return nullptr;
+    }
+
+    mLoaderMap.Put(aExt, loader);
+  }
+
+  return loader.forget();
+}
+
+NS_IMETHODIMP
+nsComponentManagerImpl::RegisterFactory(const nsCID& aClass,
+                                        const char* aName,
+                                        const char* aContractID,
+                                        nsIFactory* aFactory)
+{
+  if (!aFactory) {
+    // If a null factory is passed in, this call just wants to reset
+    // the contract ID to point to an existing CID entry.
+    if (!aContractID) {
+      return NS_ERROR_INVALID_ARG;
+    }
+
+    SafeMutexAutoLock lock(mLock);
+    nsFactoryEntry* oldf = mFactories.Get(aClass);
+    if (!oldf) {
+      return NS_ERROR_FACTORY_NOT_REGISTERED;
+    }
+
+    mContractIDs.Put(nsDependentCString(aContractID), oldf);
+    return NS_OK;
+  }
+
+  nsAutoPtr<nsFactoryEntry> f(new nsFactoryEntry(aClass, aFactory));
+
+  SafeMutexAutoLock lock(mLock);
+  nsFactoryEntry* oldf = mFactories.Get(aClass);
+  if (oldf) {
+    return NS_ERROR_FACTORY_EXISTS;
+  }
+
+  if (aContractID) {
+    mContractIDs.Put(nsDependentCString(aContractID), f);
+  }
+
+  mFactories.Put(aClass, f.forget());
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsComponentManagerImpl::UnregisterFactory(const nsCID& aClass,
+                                          nsIFactory* aFactory)
+{
+  // Don't release the dying factory or service object until releasing
+  // the component manager monitor.
+  nsCOMPtr<nsIFactory> dyingFactory;
+  nsCOMPtr<nsISupports> dyingServiceObject;
+
+  {
+    SafeMutexAutoLock lock(mLock);
+    nsFactoryEntry* f = mFactories.Get(aClass);
+    if (!f || f->mFactory != aFactory) {
+      return NS_ERROR_FACTORY_NOT_REGISTERED;
+    }
+
+    mFactories.Remove(aClass);
+
+    // This might leave a stale contractid -> factory mapping in
+    // place, so null out the factory entry (see
+    // nsFactoryEntry::GetFactory)
+    f->mFactory.swap(dyingFactory);
+    f->mServiceObject.swap(dyingServiceObject);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsComponentManagerImpl::AutoRegister(nsIFile* aLocation)
+{
+  XRE_AddManifestLocation(NS_EXTENSION_LOCATION, aLocation);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsComponentManagerImpl::AutoUnregister(nsIFile* aLocation)
+{
+  NS_ERROR("AutoUnregister not implemented.");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsComponentManagerImpl::RegisterFactoryLocation(const nsCID& aCID,
+                                                const char* aClassName,
+                                                const char* aContractID,
+                                                nsIFile* aFile,
+                                                const char* aLoaderStr,
+                                                const char* aType)
+{
+  NS_ERROR("RegisterFactoryLocation not implemented.");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsComponentManagerImpl::UnregisterFactoryLocation(const nsCID& aCID,
+                                                  nsIFile* aFile)
+{
+  NS_ERROR("UnregisterFactoryLocation not implemented.");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsComponentManagerImpl::IsCIDRegistered(const nsCID& aClass,
+                                        bool* aResult)
+{
+  *aResult = (nullptr != GetFactoryEntry(aClass));
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsComponentManagerImpl::IsContractIDRegistered(const char* aClass,
+                                               bool* aResult)
+{
+  if (NS_WARN_IF(!aClass)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsFactoryEntry* entry = GetFactoryEntry(aClass, strlen(aClass));
+
+  if (entry) {
+    // UnregisterFactory might have left a stale nsFactoryEntry in
+    // mContractIDs, so we should check to see whether this entry has
+    // anything useful.
+    *aResult = (bool(entry->mModule) ||
+                bool(entry->mFactory) ||
+                bool(entry->mServiceObject));
+  } else {
+    *aResult = false;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsComponentManagerImpl::EnumerateCIDs(nsISimpleEnumerator** aEnumerator)
+{
+  nsCOMArray<nsISupports> array;
+  for (auto iter = mFactories.Iter(); !iter.Done(); iter.Next()) {
+    const nsID& id = iter.Key();
+    nsCOMPtr<nsISupportsID> wrapper = new nsSupportsID();
+    wrapper->SetData(&id);
+    array.AppendObject(wrapper);
+  }
+  return NS_NewArrayEnumerator(aEnumerator, array);
+}
+
+NS_IMETHODIMP
+nsComponentManagerImpl::EnumerateContractIDs(nsISimpleEnumerator** aEnumerator)
+{
+  nsTArray<nsCString>* array = new nsTArray<nsCString>;
+  for (auto iter = mContractIDs.Iter(); !iter.Done(); iter.Next()) {
+    const nsACString& contract = iter.Key();
+    array->AppendElement(contract);
+  }
+
+  nsCOMPtr<nsIUTF8StringEnumerator> e;
+  nsresult rv = NS_NewAdoptingUTF8StringEnumerator(getter_AddRefs(e), array);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  return CallQueryInterface(e, aEnumerator);
+}
+
+NS_IMETHODIMP
+nsComponentManagerImpl::CIDToContractID(const nsCID& aClass,
+                                        char** aResult)
+{
+  NS_ERROR("CIDTOContractID not implemented");
+  return NS_ERROR_FACTORY_NOT_REGISTERED;
+}
+
+NS_IMETHODIMP
+nsComponentManagerImpl::ContractIDToCID(const char* aContractID,
+                                        nsCID** aResult)
+{
+  {
+    SafeMutexAutoLock lock(mLock);
+    nsFactoryEntry* entry = mContractIDs.Get(nsDependentCString(aContractID));
+    if (entry) {
+      *aResult = (nsCID*)moz_xmalloc(sizeof(nsCID));
+      **aResult = *entry->mCIDEntry->cid;
+      return NS_OK;
+    }
+  }
+  *aResult = nullptr;
+  return NS_ERROR_FACTORY_NOT_REGISTERED;
+}
+
+MOZ_DEFINE_MALLOC_SIZE_OF(ComponentManagerMallocSizeOf)
+
+NS_IMETHODIMP
+nsComponentManagerImpl::CollectReports(nsIHandleReportCallback* aHandleReport,
+                                       nsISupports* aData, bool aAnonymize)
+{
+  MOZ_COLLECT_REPORT(
+    "explicit/xpcom/component-manager", KIND_HEAP, UNITS_BYTES,
+    SizeOfIncludingThis(ComponentManagerMallocSizeOf),
+    "Memory used for the XPCOM component manager.");
+
+  return NS_OK;
+}
+
+size_t
+nsComponentManagerImpl::SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf)
+  const
+{
+  size_t n = aMallocSizeOf(this);
+
+  n += mLoaderMap.ShallowSizeOfExcludingThis(aMallocSizeOf);
+
+  n += mFactories.ShallowSizeOfExcludingThis(aMallocSizeOf);
+  for (auto iter = mFactories.ConstIter(); !iter.Done(); iter.Next()) {
+    n += iter.Data()->SizeOfIncludingThis(aMallocSizeOf);
+  }
+
+  n += mContractIDs.ShallowSizeOfExcludingThis(aMallocSizeOf);
+  for (auto iter = mContractIDs.ConstIter(); !iter.Done(); iter.Next()) {
+    // We don't measure the nsFactoryEntry data because it's owned by
+    // mFactories (which is measured above).
+    n += iter.Key().SizeOfExcludingThisIfUnshared(aMallocSizeOf);
+  }
+
+  n += sStaticModules->ShallowSizeOfIncludingThis(aMallocSizeOf);
+  n += sModuleLocations->ShallowSizeOfIncludingThis(aMallocSizeOf);
+
+  n += mKnownStaticModules.ShallowSizeOfExcludingThis(aMallocSizeOf);
+  n += mKnownModules.ShallowSizeOfExcludingThis(aMallocSizeOf);
+
+  n += PL_SizeOfArenaPoolExcludingPool(&mArena, aMallocSizeOf);
+
+  n += mPendingServices.ShallowSizeOfExcludingThis(aMallocSizeOf);
+
+  // Measurement of the following members may be added later if DMD finds it is
+  // worthwhile:
+  // - mLoaderMap's keys and values
+  // - mMon
+  // - sStaticModules' entries
+  // - sModuleLocations' entries
+  // - mNativeModuleLoader
+  // - mKnownStaticModules' entries?
+  // - mKnownModules' keys and values?
+
+  return n;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// nsFactoryEntry
+////////////////////////////////////////////////////////////////////////////////
+
+nsFactoryEntry::nsFactoryEntry(const mozilla::Module::CIDEntry* aEntry,
+                               nsComponentManagerImpl::KnownModule* aModule)
+  : mCIDEntry(aEntry)
+  , mModule(aModule)
+{
+}
+
+nsFactoryEntry::nsFactoryEntry(const nsCID& aCID, nsIFactory* aFactory)
+  : mCIDEntry(nullptr)
+  , mModule(nullptr)
+  , mFactory(aFactory)
+{
+  mozilla::Module::CIDEntry* e = new mozilla::Module::CIDEntry();
+  nsCID* cid = new nsCID;
+  *cid = aCID;
+  e->cid = cid;
+  mCIDEntry = e;
+}
+
+nsFactoryEntry::~nsFactoryEntry()
+{
+  // If this was a RegisterFactory entry, we own the CIDEntry/CID
+  if (!mModule) {
+    delete mCIDEntry->cid;
+    delete mCIDEntry;
+  }
+}
+
+already_AddRefed<nsIFactory>
+nsFactoryEntry::GetFactory()
+{
+  nsComponentManagerImpl::gComponentManager->mLock.AssertNotCurrentThreadOwns();
+
+  if (!mFactory) {
+    // RegisterFactory then UnregisterFactory can leave an entry in mContractIDs
+    // pointing to an unusable nsFactoryEntry.
+    if (!mModule) {
+      return nullptr;
+    }
+
+    if (!mModule->Load()) {
+      return nullptr;
+    }
+
+    // Don't set mFactory directly, it needs to be locked
+    nsCOMPtr<nsIFactory> factory;
+
+    if (mModule->Module()->getFactoryProc) {
+      factory = mModule->Module()->getFactoryProc(*mModule->Module(),
+                                                  *mCIDEntry);
+    } else if (mCIDEntry->getFactoryProc) {
+      factory = mCIDEntry->getFactoryProc(*mModule->Module(), *mCIDEntry);
+    } else {
+      NS_ASSERTION(mCIDEntry->constructorProc, "no getfactory or constructor");
+      factory = new mozilla::GenericFactory(mCIDEntry->constructorProc);
+    }
+    if (!factory) {
+      return nullptr;
+    }
+
+    SafeMutexAutoLock lock(nsComponentManagerImpl::gComponentManager->mLock);
+    // Threads can race to set mFactory
+    if (!mFactory) {
+      factory.swap(mFactory);
+    }
+  }
+  nsCOMPtr<nsIFactory> factory = mFactory;
+  return factory.forget();
+}
+
+size_t
+nsFactoryEntry::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf)
+{
+  size_t n = aMallocSizeOf(this);
+
+  // Measurement of the following members may be added later if DMD finds it is
+  // worthwhile:
+  // - mCIDEntry;
+  // - mModule;
+  // - mFactory;
+  // - mServiceObject;
+
+  return n;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Static Access Functions
+////////////////////////////////////////////////////////////////////////////////
+
+nsresult
+NS_GetComponentManager(nsIComponentManager** aResult)
+{
+  if (!nsComponentManagerImpl::gComponentManager) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  NS_ADDREF(*aResult = nsComponentManagerImpl::gComponentManager);
+  return NS_OK;
+}
+
+nsresult
+NS_GetServiceManager(nsIServiceManager** aResult)
+{
+  if (!nsComponentManagerImpl::gComponentManager) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  NS_ADDREF(*aResult = nsComponentManagerImpl::gComponentManager);
+  return NS_OK;
+}
+
+
+nsresult
+NS_GetComponentRegistrar(nsIComponentRegistrar** aResult)
+{
+  if (!nsComponentManagerImpl::gComponentManager) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  NS_ADDREF(*aResult = nsComponentManagerImpl::gComponentManager);
+  return NS_OK;
+}
+
+EXPORT_XPCOM_API(nsresult)
+XRE_AddStaticComponent(const mozilla::Module* aComponent)
+{
+  nsComponentManagerImpl::InitializeStaticModules();
+  nsComponentManagerImpl::sStaticModules->AppendElement(aComponent);
+
+  if (nsComponentManagerImpl::gComponentManager &&
+      nsComponentManagerImpl::NORMAL ==
+        nsComponentManagerImpl::gComponentManager->mStatus) {
+    nsComponentManagerImpl::gComponentManager->RegisterModule(aComponent,
+                                                              nullptr);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsComponentManagerImpl::AddBootstrappedManifestLocation(nsIFile* aLocation)
+{
+  nsString path;
+  nsresult rv = aLocation->GetPath(path);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (Substring(path, path.Length() - 4).EqualsLiteral(".xpi")) {
+    return XRE_AddJarManifestLocation(NS_BOOTSTRAPPED_LOCATION, aLocation);
+  }
+
+  nsCOMPtr<nsIFile> manifest =
+    CloneAndAppend(aLocation, NS_LITERAL_CSTRING("chrome.manifest"));
+  return XRE_AddManifestLocation(NS_BOOTSTRAPPED_LOCATION, manifest);
+}
+
+NS_IMETHODIMP
+nsComponentManagerImpl::RemoveBootstrappedManifestLocation(nsIFile* aLocation)
+{
+  nsCOMPtr<nsIChromeRegistry> cr = mozilla::services::GetChromeRegistryService();
+  if (!cr) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsString path;
+  nsresult rv = aLocation->GetPath(path);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  nsComponentManagerImpl::ComponentLocation elem;
+  elem.type = NS_BOOTSTRAPPED_LOCATION;
+
+  if (Substring(path, path.Length() - 4).EqualsLiteral(".xpi")) {
+    elem.location.Init(aLocation, "chrome.manifest");
+  } else {
+    nsCOMPtr<nsIFile> lf =
+      CloneAndAppend(aLocation, NS_LITERAL_CSTRING("chrome.manifest"));
+    elem.location.Init(lf);
+  }
+
+  // Remove reference.
+  nsComponentManagerImpl::sModuleLocations->RemoveElement(elem,
+                                                          ComponentLocationComparator());
+
+  rv = cr->CheckForNewChrome();
+  return rv;
+}
+
+NS_IMETHODIMP
+nsComponentManagerImpl::GetManifestLocations(nsIArray** aLocations)
+{
+  NS_ENSURE_ARG_POINTER(aLocations);
+  *aLocations = nullptr;
+
+  if (!sModuleLocations) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  nsCOMPtr<nsIMutableArray> locations = nsArray::Create();
+  nsresult rv;
+  for (uint32_t i = 0; i < sModuleLocations->Length(); ++i) {
+    ComponentLocation& l = sModuleLocations->ElementAt(i);
+    FileLocation loc = l.location;
+    nsCString uriString;
+    loc.GetURIString(uriString);
+    nsCOMPtr<nsIURI> uri;
+    rv = NS_NewURI(getter_AddRefs(uri), uriString);
+    if (NS_SUCCEEDED(rv)) {
+      locations->AppendElement(uri, false);
+    }
+  }
+
+  locations.forget(aLocations);
+  return NS_OK;
+}
+
+EXPORT_XPCOM_API(nsresult)
+XRE_AddManifestLocation(NSLocationType aType, nsIFile* aLocation)
+{
+  nsComponentManagerImpl::InitializeModuleLocations();
+  nsComponentManagerImpl::ComponentLocation* c =
+    nsComponentManagerImpl::sModuleLocations->AppendElement();
+  c->type = aType;
+  c->location.Init(aLocation);
+
+  if (nsComponentManagerImpl::gComponentManager &&
+      nsComponentManagerImpl::NORMAL ==
+        nsComponentManagerImpl::gComponentManager->mStatus) {
+    nsComponentManagerImpl::gComponentManager->RegisterManifest(aType,
+                                                                c->location,
+                                                                false);
+  }
+
+  return NS_OK;
+}
+
+EXPORT_XPCOM_API(nsresult)
+XRE_AddJarManifestLocation(NSLocationType aType, nsIFile* aLocation)
+{
+  nsComponentManagerImpl::InitializeModuleLocations();
+  nsComponentManagerImpl::ComponentLocation* c =
+    nsComponentManagerImpl::sModuleLocations->AppendElement();
+
+  c->type = aType;
+  c->location.Init(aLocation, "chrome.manifest");
+
+  if (nsComponentManagerImpl::gComponentManager &&
+      nsComponentManagerImpl::NORMAL ==
+        nsComponentManagerImpl::gComponentManager->mStatus) {
+    nsComponentManagerImpl::gComponentManager->RegisterManifest(aType,
+                                                                c->location,
+                                                                false);
+  }
+
+  return NS_OK;
+}
+
diff --git a/xpcom/components/nsComponentManager.h b/xpcom/components/nsComponentManager.h
new file mode 100644
index 000000000..f0e0f684a
--- /dev/null
+++ b/xpcom/components/nsComponentManager.h
@@ -0,0 +1,363 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsComponentManager_h__
+#define nsComponentManager_h__
+
+#include "nsXPCOM.h"
+
+#include "xpcom-private.h"
+#include "nsIComponentManager.h"
+#include "nsIComponentRegistrar.h"
+#include "nsIMemoryReporter.h"
+#include "nsIServiceManager.h"
+#include "nsIFile.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Module.h"
+#include "mozilla/ModuleLoader.h"
+#include "mozilla/Mutex.h"
+#include "nsXULAppAPI.h"
+#include "nsNativeModuleLoader.h"
+#include "nsIFactory.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "PLDHashTable.h"
+#include "prtime.h"
+#include "nsCOMPtr.h"
+#include "nsAutoPtr.h"
+#include "nsWeakReference.h"
+#include "plarena.h"
+#include "nsCOMArray.h"
+#include "nsDataHashtable.h"
+#include "nsInterfaceHashtable.h"
+#include "nsClassHashtable.h"
+#include "nsTArray.h"
+
+#include "mozilla/Omnijar.h"
+#include "mozilla/Attributes.h"
+
+struct nsFactoryEntry;
+class nsIServiceManager;
+struct PRThread;
+
+#define NS_COMPONENTMANAGER_CID                      \
+{ /* 91775d60-d5dc-11d2-92fb-00e09805570f */         \
+    0x91775d60,                                      \
+    0xd5dc,                                          \
+    0x11d2,                                          \
+    {0x92, 0xfb, 0x00, 0xe0, 0x98, 0x05, 0x57, 0x0f} \
+}
+
+/* keys for registry use */
+extern const char xpcomKeyName[];
+extern const char xpcomComponentsKeyName[];
+extern const char lastModValueName[];
+extern const char fileSizeValueName[];
+extern const char nativeComponentType[];
+extern const char staticComponentType[];
+
+#ifdef DEBUG
+#define XPCOM_CHECK_PENDING_CIDS
+#endif
+////////////////////////////////////////////////////////////////////////////////
+
+extern const mozilla::Module kXPCOMModule;
+
+/**
+ * This is a wrapper around mozilla::Mutex which provides runtime
+ * checking for a deadlock where the same thread tries to lock a mutex while
+ * it is already locked. This checking is present in both debug and release
+ * builds.
+ */
+class SafeMutex
+{
+public:
+  explicit SafeMutex(const char* aName)
+    : mMutex(aName)
+    , mOwnerThread(nullptr)
+  {
+  }
+
+  ~SafeMutex() {}
+
+  void Lock()
+  {
+    AssertNotCurrentThreadOwns();
+    mMutex.Lock();
+    MOZ_ASSERT(mOwnerThread == nullptr);
+    mOwnerThread = PR_GetCurrentThread();
+  }
+
+  void Unlock()
+  {
+    MOZ_ASSERT(mOwnerThread == PR_GetCurrentThread());
+    mOwnerThread = nullptr;
+    mMutex.Unlock();
+  }
+
+  void AssertCurrentThreadOwns() const
+  {
+    // This method is a debug-only check
+    MOZ_ASSERT(mOwnerThread == PR_GetCurrentThread());
+  }
+
+  MOZ_NEVER_INLINE void AssertNotCurrentThreadOwns() const
+  {
+    // This method is a release-mode check
+    if (PR_GetCurrentThread() == mOwnerThread) {
+      MOZ_CRASH();
+    }
+  }
+
+private:
+  mozilla::Mutex mMutex;
+  mozilla::Atomic<PRThread*, mozilla::Relaxed> mOwnerThread;
+};
+
+typedef mozilla::BaseAutoLock<SafeMutex> SafeMutexAutoLock;
+typedef mozilla::BaseAutoUnlock<SafeMutex> SafeMutexAutoUnlock;
+
+class nsComponentManagerImpl final
+  : public nsIComponentManager
+  , public nsIServiceManager
+  , public nsSupportsWeakReference
+  , public nsIComponentRegistrar
+  , public nsIInterfaceRequestor
+  , public nsIMemoryReporter
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIINTERFACEREQUESTOR
+  NS_DECL_NSICOMPONENTMANAGER
+  NS_DECL_NSICOMPONENTREGISTRAR
+  NS_DECL_NSIMEMORYREPORTER
+
+  static nsresult Create(nsISupports* aOuter, REFNSIID aIID, void** aResult);
+
+  nsresult RegistryLocationForFile(nsIFile* aFile,
+                                   nsCString& aResult);
+  nsresult FileForRegistryLocation(const nsCString& aLocation,
+                                   nsIFile** aSpec);
+
+  NS_DECL_NSISERVICEMANAGER
+
+  // nsComponentManagerImpl methods:
+  nsComponentManagerImpl();
+
+  static nsComponentManagerImpl* gComponentManager;
+  nsresult Init();
+
+  nsresult Shutdown(void);
+
+  nsresult FreeServices();
+
+  already_AddRefed<mozilla::ModuleLoader> LoaderForExtension(const nsACString& aExt);
+  nsInterfaceHashtable<nsCStringHashKey, mozilla::ModuleLoader> mLoaderMap;
+
+  already_AddRefed<nsIFactory> FindFactory(const nsCID& aClass);
+  already_AddRefed<nsIFactory> FindFactory(const char* aContractID,
+                                           uint32_t aContractIDLen);
+
+  already_AddRefed<nsIFactory> LoadFactory(nsFactoryEntry* aEntry);
+
+  nsFactoryEntry* GetFactoryEntry(const char* aContractID,
+                                  uint32_t aContractIDLen);
+  nsFactoryEntry* GetFactoryEntry(const nsCID& aClass);
+
+  nsDataHashtable<nsIDHashKey, nsFactoryEntry*> mFactories;
+  nsDataHashtable<nsCStringHashKey, nsFactoryEntry*> mContractIDs;
+
+  SafeMutex mLock;
+
+  static void InitializeStaticModules();
+  static void InitializeModuleLocations();
+
+  struct ComponentLocation
+  {
+    NSLocationType type;
+    mozilla::FileLocation location;
+  };
+
+  class ComponentLocationComparator
+  {
+  public:
+    bool Equals(const ComponentLocation& aA, const ComponentLocation& aB) const
+    {
+      return (aA.type == aB.type && aA.location.Equals(aB.location));
+    }
+  };
+
+  static nsTArray<const mozilla::Module*>* sStaticModules;
+  static nsTArray<ComponentLocation>* sModuleLocations;
+
+  nsNativeModuleLoader mNativeModuleLoader;
+
+  class KnownModule
+  {
+  public:
+    /**
+     * Static or binary module.
+     */
+    KnownModule(const mozilla::Module* aModule, mozilla::FileLocation& aFile)
+      : mModule(aModule)
+      , mFile(aFile)
+      , mLoaded(false)
+      , mFailed(false)
+    {
+    }
+
+    explicit KnownModule(const mozilla::Module* aModule)
+      : mModule(aModule)
+      , mLoaded(false)
+      , mFailed(false)
+    {
+    }
+
+    explicit KnownModule(mozilla::FileLocation& aFile)
+      : mModule(nullptr)
+      , mFile(aFile)
+      , mLoader(nullptr)
+      , mLoaded(false)
+      , mFailed(false)
+    {
+    }
+
+    ~KnownModule()
+    {
+      if (mLoaded && mModule->unloadProc) {
+        mModule->unloadProc();
+      }
+    }
+
+    bool EnsureLoader();
+    bool Load();
+
+    const mozilla::Module* Module() const { return mModule; }
+
+    /**
+     * For error logging, get a description of this module, either the
+     * file path, or <static module>.
+     */
+    nsCString Description() const;
+
+  private:
+    const mozilla::Module* mModule;
+    mozilla::FileLocation mFile;
+    nsCOMPtr<mozilla::ModuleLoader> mLoader;
+    bool mLoaded;
+    bool mFailed;
+  };
+
+  // The KnownModule is kept alive by these members, it is
+  // referenced by pointer from the factory entries.
+  nsTArray<nsAutoPtr<KnownModule>> mKnownStaticModules;
+  // The key is the URI string of the module
+  nsClassHashtable<nsCStringHashKey, KnownModule> mKnownModules;
+
+  // Mutex not held
+  void RegisterModule(const mozilla::Module* aModule,
+                      mozilla::FileLocation* aFile);
+
+
+  // Mutex held
+  void RegisterCIDEntryLocked(const mozilla::Module::CIDEntry* aEntry,
+                              KnownModule* aModule);
+  void RegisterContractIDLocked(const mozilla::Module::ContractIDEntry* aEntry);
+
+  // Mutex not held
+  void RegisterManifest(NSLocationType aType, mozilla::FileLocation& aFile,
+                        bool aChromeOnly);
+
+  struct ManifestProcessingContext
+  {
+    ManifestProcessingContext(NSLocationType aType,
+                              mozilla::FileLocation& aFile, bool aChromeOnly)
+      : mType(aType)
+      , mFile(aFile)
+      , mChromeOnly(aChromeOnly)
+    {
+    }
+
+    ~ManifestProcessingContext() {}
+
+    NSLocationType mType;
+    mozilla::FileLocation mFile;
+    bool mChromeOnly;
+  };
+
+  void ManifestManifest(ManifestProcessingContext& aCx, int aLineNo,
+                        char* const* aArgv);
+  void ManifestBinaryComponent(ManifestProcessingContext& aCx, int aLineNo,
+                               char* const* aArgv);
+  void ManifestXPT(ManifestProcessingContext& aCx, int aLineNo,
+                   char* const* aArgv);
+  void ManifestComponent(ManifestProcessingContext& aCx, int aLineNo,
+                         char* const* aArgv);
+  void ManifestContract(ManifestProcessingContext& aCx, int aLineNo,
+                        char* const* aArgv);
+  void ManifestCategory(ManifestProcessingContext& aCx, int aLineNo,
+                        char* const* aArgv);
+
+  void RereadChromeManifests(bool aChromeOnly = true);
+
+  // Shutdown
+  enum
+  {
+    NOT_INITIALIZED,
+    NORMAL,
+    SHUTDOWN_IN_PROGRESS,
+    SHUTDOWN_COMPLETE
+  } mStatus;
+
+  PLArenaPool   mArena;
+
+  struct PendingServiceInfo
+  {
+    const nsCID* cid;
+    PRThread* thread;
+  };
+
+  inline PendingServiceInfo* AddPendingService(const nsCID& aServiceCID,
+                                               PRThread* aThread);
+  inline void RemovePendingService(const nsCID& aServiceCID);
+  inline PRThread* GetPendingServiceThread(const nsCID& aServiceCID) const;
+
+  nsTArray<PendingServiceInfo> mPendingServices;
+
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
+
+private:
+  ~nsComponentManagerImpl();
+};
+
+
+#define NS_MAX_FILENAME_LEN     1024
+
+#define NS_ERROR_IS_DIR NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_XPCOM, 24)
+
+struct nsFactoryEntry
+{
+  nsFactoryEntry(const mozilla::Module::CIDEntry* aEntry,
+                 nsComponentManagerImpl::KnownModule* aModule);
+
+  // nsIComponentRegistrar.registerFactory support
+  nsFactoryEntry(const nsCID& aClass, nsIFactory* aFactory);
+
+  ~nsFactoryEntry();
+
+  already_AddRefed<nsIFactory> GetFactory();
+
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf);
+
+  const mozilla::Module::CIDEntry* mCIDEntry;
+  nsComponentManagerImpl::KnownModule* mModule;
+
+  nsCOMPtr<nsIFactory>   mFactory;
+  nsCOMPtr<nsISupports>  mServiceObject;
+};
+
+#endif // nsComponentManager_h__
diff --git a/xpcom/components/nsICategoryManager.idl b/xpcom/components/nsICategoryManager.idl
new file mode 100644
index 000000000..e33d3ed8b
--- /dev/null
+++ b/xpcom/components/nsICategoryManager.idl
@@ -0,0 +1,69 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsISimpleEnumerator;
+
+/*
+ * nsICategoryManager
+ */
+
+[scriptable, uuid(3275b2cd-af6d-429a-80d7-f0c5120342ac)]
+interface nsICategoryManager : nsISupports
+{
+    /**
+     * Get the value for the given category's entry.
+     * @param aCategory The name of the category ("protocol")
+     * @param aEntry The entry you're looking for ("http")
+     * @return The value.
+     */
+    string getCategoryEntry(in string aCategory, in string aEntry);
+    
+    /**
+     * Add an entry to a category.
+     * @param aCategory The name of the category ("protocol")
+     * @param aEntry The entry to be added ("http")
+     * @param aValue The value for the entry ("moz.httprulez.1")
+     * @param aPersist Should this data persist between invocations?
+     * @param aReplace Should we replace an existing entry?
+     * @return Previous entry, if any
+     */
+    string addCategoryEntry(in string aCategory, in string aEntry,
+			    in string aValue, in boolean aPersist,
+			    in boolean aReplace);
+
+    /**
+     * Delete an entry from the category.
+     * @param aCategory The name of the category ("protocol")
+     * @param aEntry The entry to be added ("http")
+     * @param aPersist Delete persistent data from registry, if present?
+     */
+    void deleteCategoryEntry(in string aCategory, in string aEntry,
+                               in boolean aPersist);
+
+    /**
+     * Delete a category and all entries.
+     * @param aCategory The category to be deleted.
+     */
+    void deleteCategory(in string aCategory);
+
+    /**
+     * Enumerate the entries in a category.
+     * @param aCategory The category to be enumerated.
+     * @return a simple enumerator, each result QIs to
+     *         nsISupportsCString.
+     */
+    nsISimpleEnumerator enumerateCategory(in string aCategory);
+
+    /**
+     * Enumerate all existing categories
+     * @param aCategory The category to be enumerated.
+     * @return a simple enumerator, each result QIs to
+     *         nsISupportsCString.
+     */
+    nsISimpleEnumerator enumerateCategories();
+};
+
diff --git a/xpcom/components/nsIClassInfo.idl b/xpcom/components/nsIClassInfo.idl
new file mode 100644
index 000000000..639d12aa8
--- /dev/null
+++ b/xpcom/components/nsIClassInfo.idl
@@ -0,0 +1,87 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIXPCScriptable;
+
+/**
+ * Provides information about a specific implementation class.  If you want
+ * your class to implement nsIClassInfo, see nsIClassInfoImpl.h for
+ * instructions--you most likely do not want to inherit from nsIClassInfo.
+ */
+
+[scriptable, uuid(a60569d7-d401-4677-ba63-2aa5971af25d)]
+interface nsIClassInfo : nsISupports
+{
+    /**
+     * Get an ordered list of the interface ids that instances of the class 
+     * promise to implement. Note that nsISupports is an implicit member 
+     * of any such list and need not be included. 
+     *
+     * Should set *count = 0 and *array = null and return NS_OK if getting the 
+     * list is not supported.
+     */
+    void getInterfaces(out uint32_t count, 
+                       [array, size_is(count), retval] out nsIIDPtr array);
+
+    /**
+     * Return an object to assist XPConnect in supplying JavaScript-specific
+     * behavior to callers of the instance object, or null if not needed.
+     */
+    nsIXPCScriptable getScriptableHelper();
+
+    /**
+     * A contract ID through which an instance of this class can be created
+     * (or accessed as a service, if |flags & SINGLETON|), or null.
+     */
+    readonly attribute string   contractID;
+
+    /**
+     * A human readable string naming the class, or null.
+     */
+    readonly attribute string   classDescription;
+
+    /**
+     * A class ID through which an instance of this class can be created
+     * (or accessed as a service, if |flags & SINGLETON|), or null.
+     */
+    readonly attribute nsCIDPtr classID;
+
+    /**
+     * Bitflags for 'flags' attribute.
+     */
+    const uint32_t SINGLETON            = 1 << 0;
+    const uint32_t THREADSAFE           = 1 << 1;
+    const uint32_t MAIN_THREAD_ONLY     = 1 << 2;
+    const uint32_t DOM_OBJECT           = 1 << 3;
+    const uint32_t PLUGIN_OBJECT        = 1 << 4;
+    const uint32_t SINGLETON_CLASSINFO  = 1 << 5;
+
+    /**
+     * 'flags' attribute bitflag: whether objects of this type implement
+     * nsIContent.
+     */
+    const uint32_t CONTENT_NODE         = 1 << 6;
+
+    // The high order bit is RESERVED for consumers of these flags. 
+    // No implementor of this interface should ever return flags 
+    // with this bit set.
+    const uint32_t RESERVED             = 1 << 31;
+
+
+    readonly attribute uint32_t flags;
+
+    /**
+     * Also a class ID through which an instance of this class can be created
+     * (or accessed as a service, if |flags & SINGLETON|).  If the class does
+     * not have a CID, it should return NS_ERROR_NOT_AVAILABLE.  This attribute
+     * exists so C++ callers can avoid allocating and freeing a CID, as would
+     * happen if they used classID.
+     */
+    [noscript] readonly attribute nsCID classIDNoAlloc;
+
+};
diff --git a/xpcom/components/nsIComponentManager.idl b/xpcom/components/nsIComponentManager.idl
new file mode 100644
index 000000000..1e5693a28
--- /dev/null
+++ b/xpcom/components/nsIComponentManager.idl
@@ -0,0 +1,106 @@
+/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * The nsIComponentManager interface.
+ */
+
+#include "nsISupports.idl"
+
+interface nsIFile;
+interface nsIFactory;
+interface nsIArray;
+
+[scriptable, uuid(d604ffc3-1ba3-4f6c-b65f-1ed4199364c3)]
+interface nsIComponentManager : nsISupports
+{
+    /**
+     * getClassObject
+     *
+     * Returns the factory object that can be used to create instances of
+     * CID aClass
+     *
+     * @param aClass The classid of the factory that is being requested
+     */
+    void getClassObject(in nsCIDRef aClass,
+                        in nsIIDRef aIID,
+                        [iid_is(aIID),retval] out nsQIResult result);
+
+    /**
+     * getClassObjectByContractID
+     *
+     * Returns the factory object that can be used to create instances of
+     * CID aClass
+     *
+     * @param aClass The classid of the factory that is being requested
+     */
+    void getClassObjectByContractID(in string aContractID,
+                                    in nsIIDRef aIID,
+                                    [iid_is(aIID),retval] out nsQIResult result);
+
+
+   /**
+     * createInstance
+     *
+     * Create an instance of the CID aClass and return the interface aIID.
+     *
+     * @param aClass : ClassID of object instance requested
+     * @param aDelegate : Used for aggregation
+     * @param aIID : IID of interface requested
+     */
+    void createInstance(in nsCIDRef aClass, 
+                        in nsISupports aDelegate,
+                        in nsIIDRef aIID, 
+                        [iid_is(aIID),retval] out nsQIResult result);
+
+    /**
+     * createInstanceByContractID
+     *
+     * Create an instance of the CID that implements aContractID and return the
+     * interface aIID. 
+     *
+     * @param aContractID : aContractID of object instance requested
+     * @param aDelegate : Used for aggregation
+     * @param aIID : IID of interface requested
+     */
+    void createInstanceByContractID(in string aContractID,
+                                    in nsISupports aDelegate,
+                                    in nsIIDRef aIID, 
+                                    [iid_is(aIID),retval] out nsQIResult result);
+
+    /**
+     * addBootstrappedManifestLocation
+     *
+     * Adds a bootstrapped manifest location on runtime.
+     *
+     * @param aLocation : A directory where chrome.manifest resides,
+     *                    or an XPI with it on the root.
+     */
+    void addBootstrappedManifestLocation(in nsIFile aLocation);
+
+    /**
+     * removeBootstrappedManifestLocation
+     *
+     * Removes a bootstrapped manifest location on runtime.
+     *
+     * @param aLocation : A directory where chrome.manifest resides,
+     *                    or an XPI with it on the root.
+     */
+    void removeBootstrappedManifestLocation(in nsIFile aLocation);
+
+    /**
+     * getManifestLocations
+     *
+     * Get an array of nsIURIs of all registered and builtin manifest locations.
+     */
+    nsIArray getManifestLocations();
+};
+
+
+%{ C++
+#ifdef MOZILLA_INTERNAL_API
+#include "nsComponentManagerUtils.h"
+#endif
+%} C++
diff --git a/xpcom/components/nsIComponentRegistrar.idl b/xpcom/components/nsIComponentRegistrar.idl
new file mode 100644
index 000000000..e12acdf25
--- /dev/null
+++ b/xpcom/components/nsIComponentRegistrar.idl
@@ -0,0 +1,163 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * The nsIComponentRegistrar interface.
+ */
+
+#include "nsISupports.idl"
+
+interface nsIFile;
+interface nsIFactory;
+interface nsISimpleEnumerator;
+
+[scriptable, uuid(2417cbfe-65ad-48a6-b4b6-eb84db174392)]
+interface nsIComponentRegistrar : nsISupports
+{
+    /**
+     * autoRegister
+     *
+     * Register a .manifest file, or an entire directory containing
+     * these files. Registration lasts for this run only, and is not cached.
+     *
+     * @note Formerly this method would register component files directly. This
+     *       is no longer supported.
+     */
+    void autoRegister(in nsIFile aSpec);
+
+    /**
+     * autoUnregister
+     * @status OBSOLETE: This method is no longer implemented, but preserved
+     *                   in this interface for binary compatibility with
+     *                   Mozilla 1.9.2.
+     */
+    void autoUnregister(in nsIFile aSpec);
+
+
+    /**
+     * registerFactory
+     *
+     * Register a factory with a given ContractID, CID and Class Name.
+     *
+     * @param aClass      : CID of object
+     * @param aClassName  : Class Name of CID (unused)
+     * @param aContractID : ContractID associated with CID aClass. May be null
+     *                      if no contract ID is needed.
+     * @param aFactory    : Factory that will be registered for CID aClass.
+     *                      If aFactory is null, the contract will be associated
+     *                      with a previously registered CID.
+     */
+    void registerFactory(in nsCIDRef aClass, 
+                         in string aClassName,
+                         in string aContractID, 
+                         in nsIFactory aFactory);
+
+    /**
+     * unregisterFactory
+     *
+     * Unregister a factory associated with CID aClass.
+     *
+     * @param aClass   : CID being unregistered
+     * @param aFactory : Factory previously registered to create instances of
+     *                   CID aClass.
+     *
+     * @throws NS_ERROR* Method failure.
+     */    
+    void unregisterFactory(in nsCIDRef aClass, 
+                           in nsIFactory aFactory);
+
+    /**
+     * registerFactoryLocation
+     * @status OBSOLETE: This method is no longer implemented, but preserved
+     *                   in this interface for binary compatibility with
+     *                   Mozilla 1.9.2.
+     */
+    void registerFactoryLocation(in nsCIDRef aClass, 
+                                 in string aClassName,
+                                 in string aContractID, 
+                                 in nsIFile aFile,
+                                 in string aLoaderStr, 
+                                 in string aType);
+
+    /**
+     * unregisterFactoryLocation
+     * @status OBSOLETE: This method is no longer implemented, but preserved
+     *                   in this interface for binary compatibility with
+     *                   Mozilla 1.9.2.
+     */    
+    void unregisterFactoryLocation(in nsCIDRef aClass, 
+                                   in nsIFile aFile);
+
+    /**
+     * isCIDRegistered
+     *
+     * Returns true if a factory is registered for the CID.
+     *
+     * @param aClass : CID queried for registeration
+     * @return       : true if a factory is registered for CID 
+     *                 false otherwise.
+     */
+    boolean isCIDRegistered(in nsCIDRef aClass);
+    
+    /**
+     * isContractIDRegistered
+     *
+     * Returns true if a factory is registered for the contract id.
+     *
+     * @param aClass : contract id queried for registeration
+     * @return       : true if a factory is registered for contract id 
+     *                 false otherwise.
+     */
+    boolean isContractIDRegistered(in string aContractID);
+
+    /**
+     * enumerateCIDs
+     *
+     * Enumerate the list of all registered CIDs.
+     *
+     * @return : enumerator for CIDs.  Elements of the enumeration can be QI'ed
+     *           for the nsISupportsID interface.  From the nsISupportsID, you 
+     *           can obtain the actual CID.
+     */
+    nsISimpleEnumerator enumerateCIDs();
+
+    /**
+     * enumerateContractIDs
+     *
+     * Enumerate the list of all registered ContractIDs.
+     *
+     * @return : enumerator for ContractIDs. Elements of the enumeration can be 
+     *           QI'ed for the nsISupportsCString interface.  From  the
+     *           nsISupportsCString interface, you can obtain the actual 
+     *           Contract ID string.
+     */
+    nsISimpleEnumerator enumerateContractIDs();
+
+    /**
+     * CIDToContractID
+     * @status OBSOLETE: This method is no longer implemented, but preserved
+     *                   in this interface for binary compatibility with
+     *                   Mozilla 1.9.2.
+     */
+    string   CIDToContractID(in nsCIDRef aClass);
+
+    /**
+     * contractIDToCID
+     *
+     * Returns the CID for a given Contract ID, if one exists and is registered.
+     *
+     * @return : Contract ID.
+     */
+    nsCIDPtr contractIDToCID(in string aContractID);
+};
+
+
+
+
+
+
+
+
+
+
diff --git a/xpcom/components/nsIFactory.idl b/xpcom/components/nsIFactory.idl
new file mode 100644
index 000000000..54152976f
--- /dev/null
+++ b/xpcom/components/nsIFactory.idl
@@ -0,0 +1,42 @@
+/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * A class factory allows the creation of nsISupports derived
+ * components without specifying a concrete base class.  
+ */
+
+[scriptable, object, uuid(00000001-0000-0000-c000-000000000046)]
+interface nsIFactory :  nsISupports {
+   /**
+    * Creates an instance of a component.
+    *
+    * @param aOuter Pointer to a component that wishes to be aggregated
+    *               in the resulting instance. This will be nullptr if no
+    *               aggregation is requested.
+    * @param iid    The IID of the interface being requested in
+    *               the component which is being currently created.
+    * @param result [out] Pointer to the newly created instance, if successful.
+    * @throws NS_NOINTERFACE - Interface not accessible.
+    * @throws NS_ERROR_NO_AGGREGATION - if an 'outer' object is supplied, but the
+    *                                   component is not aggregatable.
+    *         NS_ERROR* - Method failure.
+    */
+    void createInstance(in nsISupports aOuter, in nsIIDRef iid,
+                      [retval, iid_is(iid)] out nsQIResult result);
+
+   /**
+    * LockFactory provides the client a way to keep the component
+    * in memory until it is finished with it. The client can call
+    * LockFactory(PR_TRUE) to lock the factory and LockFactory(PR_FALSE)
+    * to release the factory.	 
+    *
+    * @param lock - Must be PR_TRUE or PR_FALSE
+    * @throws NS_ERROR* - Method failure.
+    */
+    void lockFactory(in boolean lock);
+};
diff --git a/xpcom/components/nsIModule.idl b/xpcom/components/nsIModule.idl
new file mode 100644
index 000000000..4570a0199
--- /dev/null
+++ b/xpcom/components/nsIModule.idl
@@ -0,0 +1,82 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIFile;
+interface nsIComponentManager;
+
+/**
+ * The nsIModule interface.
+ */
+
+[scriptable, uuid(7392D032-5371-11d3-994E-00805FD26FEE)]
+interface nsIModule : nsISupports
+{
+    /** 
+     * Object Instance Creation
+     *
+     * Obtains a Class Object from a nsIModule for a given CID and IID pair.  
+     * This class object can either be query to a nsIFactory or a may be 
+     * query to a nsIClassInfo.
+     *
+     * @param aCompMgr  : The global component manager
+     * @param aClass    : ClassID of object instance requested
+     * @param aIID      : IID of interface requested
+     * 
+     */
+    void getClassObject(in nsIComponentManager aCompMgr, 
+                        in nsCIDRef aClass,
+                        in nsIIDRef aIID,
+                        [retval, iid_is(aIID)] out nsQIResult aResult);
+
+
+    /**
+     * One time registration callback
+     *
+     * When the nsIModule is discovered, this method will be
+     * called so that any setup registration can be preformed.
+     *
+     * @param aCompMgr  : The global component manager
+     * @param aLocation : The location of the nsIModule on disk
+     * @param aLoaderStr: Opaque loader specific string
+     * @param aType     : Loader Type being used to load this module 
+     */
+    void registerSelf(in nsIComponentManager aCompMgr, 
+                      in nsIFile aLocation,
+                      in string aLoaderStr, 
+                      in string aType);
+    /**
+     * One time unregistration callback
+     *
+     * When the nsIModule is being unregistered, this method will be
+     * called so that any unregistration can be preformed
+     *
+     * @param aCompMgr   : The global component manager
+     * @param aLocation  : The location of the nsIModule on disk
+     * @param aLoaderStr : Opaque loader specific string
+     * 
+     */
+   void unregisterSelf(in nsIComponentManager aCompMgr, 
+                        in nsIFile aLocation,
+                        in string  aLoaderStr);
+
+   /** 
+    * Module load management
+    * 
+    * @param aCompMgr  : The global component manager
+    *
+    * @return indicates to the caller if the module can be unloaded.
+    * 		Returning PR_TRUE isn't a guarantee that the module will be
+    *		unloaded. It constitues only willingness of the module to be
+    *		unloaded.  It is very important to ensure that no outstanding 
+    *       references to the module's code/data exist before returning 
+    *       PR_TRUE. 
+    *		Returning PR_FALSE guaratees that the module won't be unloaded.
+    */
+    boolean canUnload(in nsIComponentManager aCompMgr);
+};
+
+
diff --git a/xpcom/components/nsIServiceManager.idl b/xpcom/components/nsIServiceManager.idl
new file mode 100644
index 000000000..45c1c3cc2
--- /dev/null
+++ b/xpcom/components/nsIServiceManager.idl
@@ -0,0 +1,72 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+#include "nsISupports.idl"
+
+/**
+ * The nsIServiceManager manager interface provides a means to obtain
+ * global services in an application. The service manager depends on the 
+ * repository to find and instantiate factories to obtain services.
+ *
+ * Users of the service manager must first obtain a pointer to the global
+ * service manager by calling NS_GetServiceManager. After that, 
+ * they can request specific services by calling GetService. When they are
+ * finished they can NS_RELEASE() the service as usual.
+ *
+ * A user of a service may keep references to particular services indefinitely
+ * and only must call Release when it shuts down.
+ */
+
+[scriptable, uuid(8bb35ed9-e332-462d-9155-4a002ab5c958)]
+interface nsIServiceManager : nsISupports
+{
+    /**
+     * getServiceByContractID
+     *
+     * Returns the instance that implements aClass or aContractID and the
+     * interface aIID.  This may result in the instance being created.
+     *
+     * @param aClass or aContractID : aClass or aContractID of object 
+     *                                instance requested
+     * @param aIID : IID of interface requested
+     * @param result : resulting service 
+     */
+    void getService(in nsCIDRef aClass, 
+		    in nsIIDRef aIID, 
+		    [iid_is(aIID),retval] out nsQIResult result);
+
+    void getServiceByContractID(in string aContractID,
+				in nsIIDRef aIID, 
+				[iid_is(aIID),retval] out nsQIResult result);
+
+    /**
+     * isServiceInstantiated
+     *
+     * isServiceInstantiated will return a true if the service has already
+     * been created, or throw otherwise
+     *
+     * @param aClass or aContractID : aClass or aContractID of object 
+     *                                instance requested
+     * @param aIID : IID of interface requested
+     * @throws NS_ERROR_SERVICE_NOT_AVAILABLE if the service hasn't been 
+     *         instantiated
+     * @throws NS_NOINTERFACE if the IID given isn't supported by the object
+     */
+    boolean isServiceInstantiated(in nsCIDRef aClass, in nsIIDRef aIID);
+    boolean isServiceInstantiatedByContractID(in string aContractID, in nsIIDRef aIID);
+};
+
+
+%{C++
+// Observing xpcom autoregistration.  Topics will be 'start' and 'stop'.
+#define NS_XPCOM_AUTOREGISTRATION_OBSERVER_ID "xpcom-autoregistration"
+
+#ifdef MOZILLA_INTERNAL_API
+#include "nsXPCOM.h"
+#include "nsComponentManagerUtils.h"
+#include "nsServiceManagerUtils.h"
+#endif
+%}
+
diff --git a/xpcom/components/nsNativeModuleLoader.cpp b/xpcom/components/nsNativeModuleLoader.cpp
new file mode 100644
index 000000000..6452f5d1b
--- /dev/null
+++ b/xpcom/components/nsNativeModuleLoader.cpp
@@ -0,0 +1,220 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * This Original Code has been modified by IBM Corporation.
+ * Modifications made by IBM described herein are
+ * Copyright (c) International Business Machines
+ * Corporation, 2000
+ *
+ * Modifications to Mozilla code or documentation
+ * identified per MPL Section 3.3
+ *
+ * Date             Modified by     Description of modification
+ * 04/20/2000       IBM Corp.      Added PR_CALLBACK for Optlink use in OS2
+ */
+
+#include "nsNativeModuleLoader.h"
+
+#include "mozilla/Logging.h"
+#include "prinit.h"
+#include "prerror.h"
+
+#include "nsComponentManager.h"
+#include "ManifestParser.h" // for LogMessage
+#include "nsCRTGlue.h"
+#include "nsThreadUtils.h"
+#include "nsTraceRefcnt.h"
+
+#include "nsIFile.h"
+#include "mozilla/WindowsDllBlocklist.h"
+
+#ifdef XP_WIN
+#include <windows.h>
+#endif
+
+#ifdef XP_MACOSX
+#include <signal.h>
+#endif
+
+#ifdef DEBUG
+#define IMPLEMENT_BREAK_AFTER_LOAD
+#endif
+
+using namespace mozilla;
+
+static LazyLogModule sNativeModuleLoaderLog("nsNativeModuleLoader");
+#define LOG(level, args) MOZ_LOG(sNativeModuleLoaderLog, level, args)
+
+nsresult
+nsNativeModuleLoader::Init()
+{
+  MOZ_ASSERT(NS_IsMainThread(), "Startup not on main thread?");
+  LOG(LogLevel::Debug, ("nsNativeModuleLoader::Init()"));
+  return NS_OK;
+}
+
+class LoadModuleMainThreadRunnable : public Runnable
+{
+public:
+  LoadModuleMainThreadRunnable(nsNativeModuleLoader* aLoader,
+                               FileLocation& aFile)
+    : mManager(nsComponentManagerImpl::gComponentManager)
+    , mLoader(aLoader)
+    , mFile(aFile)
+    , mResult(nullptr)
+  {
+  }
+
+  NS_IMETHOD Run() override
+  {
+    mResult = mLoader->LoadModule(mFile);
+    return NS_OK;
+  }
+
+  RefPtr<nsComponentManagerImpl> mManager;
+  nsNativeModuleLoader* mLoader;
+  FileLocation mFile;
+  const mozilla::Module* mResult;
+};
+
+const mozilla::Module*
+nsNativeModuleLoader::LoadModule(FileLocation& aFile)
+{
+  if (aFile.IsZip()) {
+    NS_ERROR("Binary components cannot be loaded from JARs");
+    return nullptr;
+  }
+  nsCOMPtr<nsIFile> file = aFile.GetBaseFile();
+  nsresult rv;
+
+  if (!NS_IsMainThread()) {
+    // If this call is off the main thread, synchronously proxy it
+    // to the main thread.
+    RefPtr<LoadModuleMainThreadRunnable> r =
+      new LoadModuleMainThreadRunnable(this, aFile);
+    NS_DispatchToMainThread(r, NS_DISPATCH_SYNC);
+    return r->mResult;
+  }
+
+  nsCOMPtr<nsIHashable> hashedFile(do_QueryInterface(file));
+  if (!hashedFile) {
+    NS_ERROR("nsIFile is not nsIHashable");
+    return nullptr;
+  }
+
+  nsAutoCString filePath;
+  file->GetNativePath(filePath);
+
+  NativeLoadData data;
+
+  if (mLibraries.Get(hashedFile, &data)) {
+    NS_ASSERTION(data.mModule, "Corrupt mLibraries hash");
+    LOG(LogLevel::Debug,
+        ("nsNativeModuleLoader::LoadModule(\"%s\") - found in cache",
+         filePath.get()));
+    return data.mModule;
+  }
+
+  // We haven't loaded this module before
+  {
+#ifdef HAS_DLL_BLOCKLIST
+    AutoSetXPCOMLoadOnMainThread guard;
+#endif
+    rv = file->Load(&data.mLibrary);
+  }
+
+  if (NS_FAILED(rv)) {
+    char errorMsg[1024] = "<unknown; can't get error from NSPR>";
+
+    if (PR_GetErrorTextLength() < (int)sizeof(errorMsg)) {
+      PR_GetErrorText(errorMsg);
+    }
+
+    LogMessage("Failed to load native module at path '%s': (%lx) %s",
+               filePath.get(), rv, errorMsg);
+
+    return nullptr;
+  }
+
+#ifdef IMPLEMENT_BREAK_AFTER_LOAD
+  nsAutoCString leafName;
+  file->GetNativeLeafName(leafName);
+
+  char* env = getenv("XPCOM_BREAK_ON_LOAD");
+  char* blist;
+  if (env && *env && (blist = strdup(env))) {
+    char* nextTok = blist;
+    while (char* token = NS_strtok(":", &nextTok)) {
+      if (leafName.Find(token, true) != kNotFound) {
+        NS_BREAK();
+      }
+    }
+
+    free(blist);
+  }
+#endif
+
+  void* module = PR_FindSymbol(data.mLibrary, "NSModule");
+  if (!module) {
+    LogMessage("Native module at path '%s' doesn't export symbol `NSModule`.",
+               filePath.get());
+    PR_UnloadLibrary(data.mLibrary);
+    return nullptr;
+  }
+
+  data.mModule = *(mozilla::Module const* const*)module;
+  if (mozilla::Module::kVersion != data.mModule->mVersion) {
+    LogMessage("Native module at path '%s' is incompatible with this version of Firefox, has version %i, expected %i.",
+               filePath.get(), data.mModule->mVersion,
+               mozilla::Module::kVersion);
+    PR_UnloadLibrary(data.mLibrary);
+    return nullptr;
+  }
+
+  mLibraries.Put(hashedFile, data); // infallible
+  return data.mModule;
+}
+
+void
+nsNativeModuleLoader::UnloadLibraries()
+{
+  MOZ_ASSERT(NS_IsMainThread(), "Shutdown not on main thread?");
+
+  for (auto iter = mLibraries.Iter(); !iter.Done(); iter.Next()) {
+    NativeLoadData& loadData = iter.Data();
+    loadData.mModule = nullptr;
+  }
+
+  for (auto iter = mLibraries.Iter(); !iter.Done(); iter.Next()) {
+    if (MOZ_LOG_TEST(sNativeModuleLoaderLog, LogLevel::Debug)) {
+      nsIHashable* hashedFile = iter.Key();
+      nsCOMPtr<nsIFile> file(do_QueryInterface(hashedFile));
+
+      nsAutoCString filePath;
+      file->GetNativePath(filePath);
+
+      LOG(LogLevel::Debug,
+          ("nsNativeModuleLoader::UnloaderFunc(\"%s\")", filePath.get()));
+    }
+
+#ifdef NS_BUILD_REFCNT_LOGGING
+    nsTraceRefcnt::SetActivityIsLegal(false);
+#endif
+
+#if 0
+    // XXXbsmedberg: do this as soon as the static-destructor crash(es)
+    // are fixed
+    NativeLoadData& loadData = iter.Data();
+    PRStatus ret = PR_UnloadLibrary(loadData.mLibrary);
+    NS_ASSERTION(ret == PR_SUCCESS, "Failed to unload library");
+#endif
+
+#ifdef NS_BUILD_REFCNT_LOGGING
+    nsTraceRefcnt::SetActivityIsLegal(true);
+#endif
+
+    iter.Remove();
+  }
+}
diff --git a/xpcom/components/nsNativeModuleLoader.h b/xpcom/components/nsNativeModuleLoader.h
new file mode 100644
index 000000000..b05a4a7a2
--- /dev/null
+++ b/xpcom/components/nsNativeModuleLoader.h
@@ -0,0 +1,39 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsNativeModuleLoader_h__
+#define nsNativeModuleLoader_h__
+
+#include "nsDataHashtable.h"
+#include "nsHashKeys.h"
+#include "prlink.h"
+
+namespace mozilla {
+class FileLocation;
+} // namespace mozilla
+
+class nsNativeModuleLoader final
+{
+public:
+  const mozilla::Module* LoadModule(mozilla::FileLocation& aFile);
+
+  nsresult Init();
+
+  void UnloadLibraries();
+
+private:
+  struct NativeLoadData
+  {
+    NativeLoadData() : mModule(nullptr), mLibrary(nullptr) {}
+
+    const mozilla::Module* mModule;
+    PRLibrary* mLibrary;
+  };
+
+  nsDataHashtable<nsHashableHashKey, NativeLoadData> mLibraries;
+};
+
+#endif /* nsNativeModuleLoader_h__ */
diff --git a/xpcom/doc/README b/xpcom/doc/README
new file mode 100644
index 000000000..6817f789f
--- /dev/null
+++ b/xpcom/doc/README
@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <title>READ ME</title>
+  </head>
+  <body>
+    <h4>
+      XPCOM documentation can be found at <a href="https://developer.mozilla.org/en-US/docs/XPCOM">https://developer.mozilla.org/en-US/docs/XPCOM</a>
+    </h4>
+  </body>
+</html>
diff --git a/xpcom/ds/IncrementalTokenizer.cpp b/xpcom/ds/IncrementalTokenizer.cpp
new file mode 100644
index 000000000..429428516
--- /dev/null
+++ b/xpcom/ds/IncrementalTokenizer.cpp
@@ -0,0 +1,195 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+* License, v. 2.0. If a copy of the MPL was not distributed with this
+* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/IncrementalTokenizer.h"
+
+#include "mozilla/AutoRestore.h"
+
+#include "nsIInputStream.h"
+#include "IncrementalTokenizer.h"
+#include <algorithm>
+
+namespace mozilla {
+
+IncrementalTokenizer::IncrementalTokenizer(Consumer aConsumer,
+                                           const char * aWhitespaces,
+                                           const char * aAdditionalWordChars,
+                                           uint32_t aRawMinBuffered)
+  : TokenizerBase(aWhitespaces, aAdditionalWordChars)
+#ifdef DEBUG
+  , mConsuming(false)
+#endif
+  , mNeedMoreInput(false)
+  , mRollback(false)
+  , mInputCursor(0)
+  , mConsumer(aConsumer)
+{
+  mInputFinished = false;
+  mMinRawDelivery = aRawMinBuffered;
+}
+
+nsresult IncrementalTokenizer::FeedInput(const nsACString & aInput)
+{
+  NS_ENSURE_TRUE(mConsumer, NS_ERROR_NOT_INITIALIZED);
+  MOZ_ASSERT(!mInputFinished);
+
+  mInput.Cut(0, mInputCursor);
+  mInputCursor = 0;
+
+  mInput.Append(aInput);
+
+  return Process();
+}
+
+nsresult IncrementalTokenizer::FeedInput(nsIInputStream * aInput, uint32_t aCount)
+{
+  NS_ENSURE_TRUE(mConsumer, NS_ERROR_NOT_INITIALIZED);
+  MOZ_ASSERT(!mInputFinished);
+  MOZ_ASSERT(!mConsuming);
+
+  mInput.Cut(0, mInputCursor);
+  mInputCursor = 0;
+
+  nsresult rv = NS_OK;
+  while (NS_SUCCEEDED(rv) && aCount) {
+    nsCString::index_type remainder = mInput.Length();
+    nsCString::index_type load =
+      std::min<nsCString::index_type>(aCount, PR_UINT32_MAX - remainder);
+
+    if (!load) {
+      // To keep the API simple, we fail if the input data buffer if filled.
+      // It's highly unlikely there will ever be such amout of data cumulated
+      // unless a logic fault in the consumer code.
+      NS_ERROR("IncrementalTokenizer consumer not reading data?");
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    if (!mInput.SetLength(remainder + load, fallible)) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    nsCString::char_iterator buffer = mInput.BeginWriting() + remainder;
+
+    uint32_t read;
+    rv = aInput->Read(buffer, load, &read);
+    if (NS_SUCCEEDED(rv)) {
+      // remainder + load fits the uint32_t size, so must remainder + read.
+      mInput.SetLength(remainder + read);
+      aCount -= read;
+
+      rv = Process();
+    }
+  }
+
+  return rv;
+}
+
+nsresult IncrementalTokenizer::FinishInput()
+{
+  NS_ENSURE_TRUE(mConsumer, NS_ERROR_NOT_INITIALIZED);
+  MOZ_ASSERT(!mInputFinished);
+  MOZ_ASSERT(!mConsuming);
+
+  mInput.Cut(0, mInputCursor);
+  mInputCursor = 0;
+
+  mInputFinished = true;
+  nsresult rv = Process();
+  mConsumer = nullptr;
+  return rv;
+}
+
+bool IncrementalTokenizer::Next(Token & aToken)
+{
+  // Assert we are called only from the consumer callback
+  MOZ_ASSERT(mConsuming);
+
+  if (mPastEof) {
+    return false;
+  }
+
+  nsACString::const_char_iterator next = Parse(aToken);
+  mPastEof = aToken.Type() == TOKEN_EOF;
+  if (next == mCursor && !mPastEof) {
+    // Not enough input to make a deterministic decision.
+    return false;
+  }
+
+  AssignFragment(aToken, mCursor, next);
+  mCursor = next;
+  return true;
+}
+
+void IncrementalTokenizer::NeedMoreInput()
+{
+  // Assert we are called only from the consumer callback
+  MOZ_ASSERT(mConsuming);
+
+  // When the input has been finished, we can't set the flag to prevent
+  // indefinite wait for more input (that will never come)
+  mNeedMoreInput = !mInputFinished;
+}
+
+void IncrementalTokenizer::Rollback()
+{
+  // Assert we are called only from the consumer callback
+  MOZ_ASSERT(mConsuming);
+
+  mRollback = true;
+}
+
+nsresult IncrementalTokenizer::Process()
+{
+#ifdef DEBUG
+  // Assert we are not re-entered
+  MOZ_ASSERT(!mConsuming);
+
+  AutoRestore<bool> consuming(mConsuming);
+  mConsuming = true;
+#endif
+
+  MOZ_ASSERT(!mPastEof);
+
+  nsresult rv = NS_OK;
+
+  mInput.BeginReading(mCursor);
+  mCursor += mInputCursor;
+  mInput.EndReading(mEnd);
+
+  while (NS_SUCCEEDED(rv) && !mPastEof) {
+    Token token;
+    nsACString::const_char_iterator next = Parse(token);
+    mPastEof = token.Type() == TOKEN_EOF;
+    if (next == mCursor && !mPastEof) {
+      // Not enough input to make a deterministic decision.
+      break;
+    }
+
+    AssignFragment(token, mCursor, next);
+
+    nsACString::const_char_iterator rollback = mCursor;
+    mCursor = next;
+
+    mNeedMoreInput = mRollback = false;
+
+    rv = mConsumer(token, *this);
+    if (NS_FAILED(rv)) {
+      break;
+    }
+    if (mNeedMoreInput || mRollback) {
+      mCursor = rollback;
+      mPastEof = false;
+      if (mNeedMoreInput) {
+        break;
+      }
+    }
+  }
+
+  mInputCursor = mCursor - mInput.BeginReading();
+  return rv;
+}
+
+} // mozilla
diff --git a/xpcom/ds/IncrementalTokenizer.h b/xpcom/ds/IncrementalTokenizer.h
new file mode 100644
index 000000000..f93668e63
--- /dev/null
+++ b/xpcom/ds/IncrementalTokenizer.h
@@ -0,0 +1,122 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+* License, v. 2.0. If a copy of the MPL was not distributed with this
+* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef INCREMENTAL_TOKENIZER_H__
+#define INCREMENTAL_TOKENIZER_H__
+
+#include "mozilla/Tokenizer.h"
+
+#include "nsError.h"
+#include <functional>
+
+class nsIInputStream;
+
+namespace mozilla {
+
+class IncrementalTokenizer : public TokenizerBase
+{
+public:
+  /**
+   * The consumer callback.  The function is called for every single token
+   * as found in the input.  Failure result returned by this callback stops
+   * the tokenization immediately and bubbles to result of Feed/FinishInput.
+   *
+   * Fragment()s of consumed tokens are ensured to remain valid until next call to
+   * Feed/FinishInput and are pointing to a single linear buffer.  Hence, those can
+   * be safely used to accumulate the data for processing after Feed/FinishInput
+   * returned.
+   */
+  typedef std::function<nsresult(Token const&, IncrementalTokenizer& i)> Consumer;
+
+  /**
+   * For aWhitespaces and aAdditionalWordChars arguments see TokenizerBase.
+   *
+   * @param aConsumer
+   *    A mandatory non-null argument, a function that consumes the tokens as they
+   *    come when the tokenizer is fed.
+   * @param aRawMinBuffered
+   *    When we have buffered at least aRawMinBuffered data, but there was no custom
+   *    token found so far because of too small incremental feed chunks, deliver
+   *    the raw data to preserve streaming and to save memory.  This only has effect
+   *    in OnlyCustomTokenizing mode.
+   */
+  explicit IncrementalTokenizer(Consumer aConsumer,
+                                const char* aWhitespaces = nullptr,
+                                const char* aAdditionalWordChars = nullptr,
+                                uint32_t aRawMinBuffered = 1024);
+
+  /**
+   * Pushes the input to be tokenized.  These directly call the Consumer callback
+   * on every found token.  Result of the Consumer callback is returned here.
+   *
+   * The tokenizer must be initialized with a valid consumer prior call to these
+   * methods.  It's not allowed to call Feed/FinishInput from inside the Consumer
+   * callback.
+   */
+  nsresult FeedInput(const nsACString& aInput);
+  nsresult FeedInput(nsIInputStream* aInput, uint32_t aCount);
+  nsresult FinishInput();
+
+  /**
+   * Can only be called from inside the consumer callback.
+   *
+   * When there is still anything to read from the input, tokenize it, store
+   * the token type and value to aToken result and shift the cursor past this
+   * just parsed token.  Each call to Next() reads another token from
+   * the input and shifts the cursor.
+   *
+   * Returns false if there is not enough data to deterministically recognize
+   * tokens or when the last returned token was EOF.
+   */
+  MOZ_MUST_USE
+  bool Next(Token& aToken);
+
+  /**
+   * Can only be called from inside the consumer callback.
+   *
+   * Tells the tokenizer to revert the cursor and stop the async parsing until
+   * next feed of the input.  This is useful when more than one token is needed
+   * to decide on the syntax but there is not enough input to get a next token
+   * (Next() returned false.)
+   */
+  void NeedMoreInput();
+
+  /**
+   * Can only be called from inside the consumer callback.
+   *
+   * This makes the consumer callback be called again while parsing
+   * the input at the previous cursor position again.  This is useful when
+   * the tokenizer state (custom tokens, tokenization mode) has changed and
+   * we want to re-parse the input again.
+   */
+  void Rollback();
+
+private:
+  // Loops over the input with TokenizerBase::Parse and calls the Consumer callback.
+  nsresult Process();
+
+#ifdef DEBUG
+  // True when inside the consumer callback, used only for assertions.
+  bool mConsuming;
+#endif // DEBUG
+  // Modifyable only from the Consumer callback, tells the parser to break, rollback
+  // and wait for more input.
+  bool mNeedMoreInput;
+  // Modifyable only from the Consumer callback, tells the parser to rollback and
+  // parse the input again, with (if modified) new settings of the tokenizer.
+  bool mRollback;
+  // The input buffer.  Updated with each call to Feed/FinishInput.
+  nsCString mInput;
+  // Numerical index pointing at the current cursor position.  We don't keep direct
+  // reference to the string buffer since the buffer gets often reallocated.
+  nsCString::index_type mInputCursor;
+  // Refernce to the consumer function.
+  Consumer mConsumer;
+};
+
+} // mozilla
+
+#endif
diff --git a/xpcom/ds/StickyTimeDuration.h b/xpcom/ds/StickyTimeDuration.h
new file mode 100644
index 000000000..39a887dbc
--- /dev/null
+++ b/xpcom/ds/StickyTimeDuration.h
@@ -0,0 +1,267 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_StickyTimeDuration_h
+#define mozilla_StickyTimeDuration_h
+
+#include "mozilla/TimeStamp.h"
+#include "mozilla/FloatingPoint.h"
+
+namespace mozilla {
+
+/**
+ * A ValueCalculator class that performs additional checks before performing
+ * arithmetic operations such that if either operand is Forever (or the
+ * negative equivalent) the result remains Forever (or the negative equivalent
+ * as appropriate).
+ *
+ * Currently this only checks if either argument to each operation is
+ * Forever/-Forever. However, it is possible that, for example,
+ * aA + aB > INT64_MAX (or < INT64_MIN).
+ *
+ * We currently don't check for that case since we don't expect that to
+ * happen often except under test conditions in which case the wrapping
+ * behavior is probably acceptable.
+ */
+class StickyTimeDurationValueCalculator
+{
+public:
+  static int64_t
+  Add(int64_t aA, int64_t aB)
+  {
+    MOZ_ASSERT((aA != INT64_MAX || aB != INT64_MIN) &&
+               (aA != INT64_MIN || aB != INT64_MAX),
+               "'Infinity + -Infinity' and '-Infinity + Infinity'"
+               " are undefined");
+
+    // Forever + x = Forever
+    // x + Forever = Forever
+    if (aA == INT64_MAX || aB == INT64_MAX) {
+      return INT64_MAX;
+    }
+    // -Forever + x = -Forever
+    // x + -Forever = -Forever
+    if (aA == INT64_MIN || aB == INT64_MIN) {
+      return INT64_MIN;
+    }
+
+    return aA + aB;
+  }
+
+  // Note that we can't just define Add and have BaseTimeDuration call Add with
+  // negative arguments since INT64_MAX != -INT64_MIN so the saturating logic
+  // won't work.
+  static int64_t
+  Subtract(int64_t aA, int64_t aB)
+  {
+    MOZ_ASSERT((aA != INT64_MAX && aA != INT64_MIN) || aA != aB,
+               "'Infinity - Infinity' and '-Infinity - -Infinity'"
+               " are undefined");
+
+    // Forever - x  = Forever
+    // x - -Forever = Forever
+    if (aA == INT64_MAX || aB == INT64_MIN) {
+      return INT64_MAX;
+    }
+    // -Forever - x = -Forever
+    // x - Forever  = -Forever
+    if (aA == INT64_MIN || aB == INT64_MAX) {
+      return INT64_MIN;
+    }
+
+    return aA - aB;
+  }
+
+  template <typename T>
+  static int64_t
+  Multiply(int64_t aA, T aB) {
+    // Specializations for double, float, and int64_t are provided following.
+    return Multiply(aA, static_cast<int64_t>(aB));
+  }
+
+  static int64_t
+  Divide(int64_t aA, int64_t aB) {
+    MOZ_ASSERT(aB != 0, "Division by zero");
+    MOZ_ASSERT((aA != INT64_MAX && aA != INT64_MIN) ||
+               (aB != INT64_MAX && aB != INT64_MIN),
+               "Dividing +/-Infinity by +/-Infinity is undefined");
+
+    // Forever / +x = Forever
+    // Forever / -x = -Forever
+    // -Forever / +x = -Forever
+    // -Forever / -x = Forever
+    if (aA == INT64_MAX || aA == INT64_MIN) {
+      return (aA >= 0) ^ (aB >= 0) ? INT64_MIN : INT64_MAX;
+    }
+    // x /  Forever = 0
+    // x / -Forever = 0
+    if (aB == INT64_MAX || aB == INT64_MIN) {
+      return 0;
+    }
+
+    return aA / aB;
+  }
+
+  static double
+  DivideDouble(int64_t aA, int64_t aB)
+  {
+    MOZ_ASSERT(aB != 0, "Division by zero");
+    MOZ_ASSERT((aA != INT64_MAX && aA != INT64_MIN) ||
+               (aB != INT64_MAX && aB != INT64_MIN),
+               "Dividing +/-Infinity by +/-Infinity is undefined");
+
+    // Forever / +x = Forever
+    // Forever / -x = -Forever
+    // -Forever / +x = -Forever
+    // -Forever / -x = Forever
+    if (aA == INT64_MAX || aA == INT64_MIN) {
+      return (aA >= 0) ^ (aB >= 0)
+             ? NegativeInfinity<double>()
+             : PositiveInfinity<double>();
+    }
+    // x /  Forever = 0
+    // x / -Forever = 0
+    if (aB == INT64_MAX || aB == INT64_MIN) {
+      return 0.0;
+    }
+
+    return static_cast<double>(aA) / aB;
+  }
+
+  static int64_t
+  Modulo(int64_t aA, int64_t aB)
+  {
+    MOZ_ASSERT(aA != INT64_MAX && aA != INT64_MIN,
+               "Infinity modulo x is undefined");
+
+    return aA % aB;
+  }
+};
+
+template <>
+inline int64_t
+StickyTimeDurationValueCalculator::Multiply<int64_t>(int64_t aA,
+                                                          int64_t aB)
+{
+  MOZ_ASSERT((aA != 0 || (aB != INT64_MIN && aB != INT64_MAX)) &&
+             ((aA != INT64_MIN && aA != INT64_MAX) || aB != 0),
+             "Multiplication of infinity by zero");
+
+  // Forever  * +x = Forever
+  // Forever  * -x = -Forever
+  // -Forever * +x = -Forever
+  // -Forever * -x = Forever
+  //
+  // i.e. If one or more of the arguments is +/-Forever, then
+  // return -Forever if the signs differ, or +Forever otherwise.
+  if (aA == INT64_MAX || aA == INT64_MIN ||
+      aB == INT64_MAX || aB == INT64_MIN) {
+    return (aA >= 0) ^ (aB >= 0) ? INT64_MIN : INT64_MAX;
+  }
+
+  return aA * aB;
+}
+
+template <>
+inline int64_t
+StickyTimeDurationValueCalculator::Multiply<double>(int64_t aA, double aB)
+{
+  MOZ_ASSERT((aA != 0 || (!IsInfinite(aB))) &&
+             ((aA != INT64_MIN && aA != INT64_MAX) || aB != 0.0),
+             "Multiplication of infinity by zero");
+
+  // As with Multiply<int64_t>, if one or more of the arguments is
+  // +/-Forever or +/-Infinity, then return -Forever if the signs differ,
+  // or +Forever otherwise.
+  if (aA == INT64_MAX || aA == INT64_MIN || IsInfinite(aB)) {
+    return (aA >= 0) ^ (aB >= 0.0) ? INT64_MIN : INT64_MAX;
+  }
+
+  return aA * aB;
+}
+
+template <>
+inline int64_t
+StickyTimeDurationValueCalculator::Multiply<float>(int64_t aA, float aB)
+{
+  MOZ_ASSERT(IsInfinite(aB) == IsInfinite(static_cast<double>(aB)),
+             "Casting to float loses infinite-ness");
+
+  return Multiply(aA, static_cast<double>(aB));
+}
+
+/**
+ * Specialization of BaseTimeDuration that uses
+ * StickyTimeDurationValueCalculator for arithmetic on the mValue member.
+ *
+ * Use this class when you need a time duration that is expected to hold values
+ * of Forever (or the negative equivalent) *and* when you expect that
+ * time duration to be used in arithmetic operations (and not just value
+ * comparisons).
+ */
+typedef BaseTimeDuration<StickyTimeDurationValueCalculator>
+  StickyTimeDuration;
+
+// Template specializations to allow arithmetic between StickyTimeDuration
+// and TimeDuration objects by falling back to the safe behavior.
+inline StickyTimeDuration
+operator+(const TimeDuration& aA, const StickyTimeDuration& aB)
+{
+  return StickyTimeDuration(aA) + aB;
+}
+inline StickyTimeDuration
+operator+(const StickyTimeDuration& aA, const TimeDuration& aB)
+{
+  return aA + StickyTimeDuration(aB);
+}
+
+inline StickyTimeDuration
+operator-(const TimeDuration& aA, const StickyTimeDuration& aB)
+{
+  return StickyTimeDuration(aA) - aB;
+}
+inline StickyTimeDuration
+operator-(const StickyTimeDuration& aA, const TimeDuration& aB)
+{
+  return aA - StickyTimeDuration(aB);
+}
+
+inline StickyTimeDuration&
+operator+=(StickyTimeDuration &aA, const TimeDuration& aB)
+{
+  return aA += StickyTimeDuration(aB);
+}
+inline StickyTimeDuration&
+operator-=(StickyTimeDuration &aA, const TimeDuration& aB)
+{
+  return aA -= StickyTimeDuration(aB);
+}
+
+inline double
+operator/(const TimeDuration& aA, const StickyTimeDuration& aB)
+{
+  return StickyTimeDuration(aA) / aB;
+}
+inline double
+operator/(const StickyTimeDuration& aA, const TimeDuration& aB)
+{
+  return aA / StickyTimeDuration(aB);
+}
+
+inline StickyTimeDuration
+operator%(const TimeDuration& aA, const StickyTimeDuration& aB)
+{
+  return StickyTimeDuration(aA) % aB;
+}
+inline StickyTimeDuration
+operator%(const StickyTimeDuration& aA, const TimeDuration& aB)
+{
+  return aA % StickyTimeDuration(aB);
+}
+
+} // namespace mozilla
+
+#endif /* mozilla_StickyTimeDuration_h */
diff --git a/xpcom/ds/Tokenizer.cpp b/xpcom/ds/Tokenizer.cpp
new file mode 100644
index 000000000..66cc1ebb7
--- /dev/null
+++ b/xpcom/ds/Tokenizer.cpp
@@ -0,0 +1,738 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "Tokenizer.h"
+
+#include "nsUnicharUtils.h"
+#include <algorithm>
+
+namespace mozilla {
+
+static const char sWhitespaces[] = " \t";
+
+Tokenizer::Tokenizer(const nsACString& aSource,
+                     const char* aWhitespaces,
+                     const char* aAdditionalWordChars)
+  : TokenizerBase(aWhitespaces, aAdditionalWordChars)
+{
+  mInputFinished = true;
+  aSource.BeginReading(mCursor);
+  mRecord = mRollback = mCursor;
+  aSource.EndReading(mEnd);
+}
+
+Tokenizer::Tokenizer(const char* aSource,
+                     const char* aWhitespaces,
+                     const char* aAdditionalWordChars)
+  : Tokenizer(nsDependentCString(aSource), aWhitespaces, aAdditionalWordChars)
+{
+}
+
+bool
+Tokenizer::Next(Token& aToken)
+{
+  if (!HasInput()) {
+    mHasFailed = true;
+    return false;
+  }
+
+  mRollback = mCursor;
+  mCursor = Parse(aToken);
+
+  AssignFragment(aToken, mRollback, mCursor);
+
+  mPastEof = aToken.Type() == TOKEN_EOF;
+  mHasFailed = false;
+  return true;
+}
+
+bool
+Tokenizer::Check(const TokenType aTokenType, Token& aResult)
+{
+  if (!HasInput()) {
+    mHasFailed = true;
+    return false;
+  }
+
+  nsACString::const_char_iterator next = Parse(aResult);
+  if (aTokenType != aResult.Type()) {
+    mHasFailed = true;
+    return false;
+  }
+
+  mRollback = mCursor;
+  mCursor = next;
+
+  AssignFragment(aResult, mRollback, mCursor);
+
+  mPastEof = aResult.Type() == TOKEN_EOF;
+  mHasFailed = false;
+  return true;
+}
+
+bool
+Tokenizer::Check(const Token& aToken)
+{
+  if (!HasInput()) {
+    mHasFailed = true;
+    return false;
+  }
+
+  Token parsed;
+  nsACString::const_char_iterator next = Parse(parsed);
+  if (!aToken.Equals(parsed)) {
+    mHasFailed = true;
+    return false;
+  }
+
+  mRollback = mCursor;
+  mCursor = next;
+  mPastEof = parsed.Type() == TOKEN_EOF;
+  mHasFailed = false;
+  return true;
+}
+
+void
+Tokenizer::SkipWhites(WhiteSkipping aIncludeNewLines)
+{
+  if (!CheckWhite() && (aIncludeNewLines == DONT_INCLUDE_NEW_LINE || !CheckEOL())) {
+    return;
+  }
+
+  nsACString::const_char_iterator rollback = mRollback;
+  while (CheckWhite() || (aIncludeNewLines == INCLUDE_NEW_LINE && CheckEOL())) {
+  }
+
+  mHasFailed = false;
+  mRollback = rollback;
+}
+
+void
+Tokenizer::SkipUntil(Token const& aToken)
+{
+  nsACString::const_char_iterator rollback = mCursor;
+  const Token eof = Token::EndOfFile();
+
+  Token t;
+  while (Next(t)) {
+    if (aToken.Equals(t) || eof.Equals(t)) {
+      Rollback();
+      break;
+    }
+  }
+
+  mRollback = rollback;
+}
+
+bool
+Tokenizer::CheckChar(bool (*aClassifier)(const char aChar))
+{
+  if (!aClassifier) {
+    MOZ_ASSERT(false);
+    return false;
+  }
+
+  if (!HasInput() || mCursor == mEnd) {
+    mHasFailed = true;
+    return false;
+  }
+
+  if (!aClassifier(*mCursor)) {
+    mHasFailed = true;
+    return false;
+  }
+
+  mRollback = mCursor;
+  ++mCursor;
+  mHasFailed = false;
+  return true;
+}
+
+bool
+Tokenizer::ReadChar(char* aValue)
+{
+  MOZ_RELEASE_ASSERT(aValue);
+
+  Token t;
+  if (!Check(TOKEN_CHAR, t)) {
+    return false;
+  }
+
+  *aValue = t.AsChar();
+  return true;
+}
+
+bool
+Tokenizer::ReadChar(bool (*aClassifier)(const char aChar), char* aValue)
+{
+  MOZ_RELEASE_ASSERT(aValue);
+
+  if (!CheckChar(aClassifier)) {
+    return false;
+  }
+
+  *aValue = *mRollback;
+  return true;
+}
+
+bool
+Tokenizer::ReadWord(nsACString& aValue)
+{
+  Token t;
+  if (!Check(TOKEN_WORD, t)) {
+    return false;
+  }
+
+  aValue.Assign(t.AsString());
+  return true;
+}
+
+bool
+Tokenizer::ReadWord(nsDependentCSubstring& aValue)
+{
+  Token t;
+  if (!Check(TOKEN_WORD, t)) {
+    return false;
+  }
+
+  aValue.Rebind(t.AsString().BeginReading(), t.AsString().Length());
+  return true;
+}
+
+bool
+Tokenizer::ReadUntil(Token const& aToken, nsACString& aResult, ClaimInclusion aInclude)
+{
+  nsDependentCSubstring substring;
+  bool rv = ReadUntil(aToken, substring, aInclude);
+  aResult.Assign(substring);
+  return rv;
+}
+
+bool
+Tokenizer::ReadUntil(Token const& aToken, nsDependentCSubstring& aResult, ClaimInclusion aInclude)
+{
+  Record();
+  nsACString::const_char_iterator rollback = mCursor;
+
+  bool found = false;
+  Token t;
+  while (Next(t)) {
+    if (aToken.Equals(t)) {
+      found = true;
+      break;
+    }
+  }
+
+  Claim(aResult, aInclude);
+  mRollback = rollback;
+  return found;
+}
+
+void
+Tokenizer::Rollback()
+{
+  MOZ_ASSERT(mCursor > mRollback || mPastEof,
+             "Tokenizer::Rollback() cannot use twice or before any parsing");
+
+  mPastEof = false;
+  mHasFailed = false;
+  mCursor = mRollback;
+}
+
+void
+Tokenizer::Record(ClaimInclusion aInclude)
+{
+  mRecord = aInclude == INCLUDE_LAST
+    ? mRollback
+    : mCursor;
+}
+
+void
+Tokenizer::Claim(nsACString& aResult, ClaimInclusion aInclusion)
+{
+  nsACString::const_char_iterator close = aInclusion == EXCLUDE_LAST
+    ? mRollback
+    : mCursor;
+  aResult.Assign(Substring(mRecord, close));
+}
+
+void
+Tokenizer::Claim(nsDependentCSubstring& aResult, ClaimInclusion aInclusion)
+{
+  nsACString::const_char_iterator close = aInclusion == EXCLUDE_LAST
+    ? mRollback
+    : mCursor;
+  aResult.Rebind(mRecord, close - mRecord);
+}
+
+// TokenizerBase
+
+TokenizerBase::TokenizerBase(const char* aWhitespaces,
+                             const char* aAdditionalWordChars)
+  : mPastEof(false)
+  , mHasFailed(false)
+  , mInputFinished(true)
+  , mMode(Mode::FULL)
+  , mMinRawDelivery(1024)
+  , mWhitespaces(aWhitespaces ? aWhitespaces : sWhitespaces)
+  , mAdditionalWordChars(aAdditionalWordChars)
+  , mCursor(nullptr)
+  , mEnd(nullptr)
+  , mNextCustomTokenID(TOKEN_CUSTOM0)
+{
+}
+
+TokenizerBase::Token
+TokenizerBase::AddCustomToken(const nsACString & aValue,
+                              ECaseSensitivity aCaseInsensitivity, bool aEnabled)
+{
+  MOZ_ASSERT(!aValue.IsEmpty());
+
+  UniquePtr<Token>& t = *mCustomTokens.AppendElement();
+  t = MakeUnique<Token>();
+
+  t->mType = static_cast<TokenType>(++mNextCustomTokenID);
+  t->mCustomCaseInsensitivity = aCaseInsensitivity;
+  t->mCustomEnabled = aEnabled;
+  t->mCustom.Assign(aValue);
+  return *t;
+}
+
+void
+TokenizerBase::RemoveCustomToken(Token& aToken)
+{
+  if (aToken.mType == TOKEN_UNKNOWN) {
+    // Already removed
+    return;
+  }
+
+  for (UniquePtr<Token> const& custom : mCustomTokens) {
+    if (custom->mType == aToken.mType) {
+      mCustomTokens.RemoveElement(custom);
+      aToken.mType = TOKEN_UNKNOWN;
+      return;
+    }
+  }
+
+  MOZ_ASSERT(false, "Token to remove not found");
+}
+
+void
+TokenizerBase::EnableCustomToken(Token const& aToken, bool aEnabled)
+{
+  if (aToken.mType == TOKEN_UNKNOWN) {
+    // Already removed
+    return;
+  }
+
+  for (UniquePtr<Token> const& custom : mCustomTokens) {
+    if (custom->Type() == aToken.Type()) {
+      // This effectively destroys the token instance.
+      custom->mCustomEnabled = aEnabled;
+      return;
+    }
+  }
+
+  MOZ_ASSERT(false, "Token to change not found");
+}
+
+void
+TokenizerBase::SetTokenizingMode(Mode aMode)
+{
+  mMode = aMode;
+}
+
+bool
+TokenizerBase::HasFailed() const
+{
+  return mHasFailed;
+}
+
+bool
+TokenizerBase::HasInput() const
+{
+  return !mPastEof;
+}
+
+nsACString::const_char_iterator
+TokenizerBase::Parse(Token& aToken) const
+{
+  if (mCursor == mEnd) {
+    if (!mInputFinished) {
+      return mCursor;
+    }
+
+    aToken = Token::EndOfFile();
+    return mEnd;
+  }
+
+  nsACString::size_type available = mEnd - mCursor;
+
+  uint32_t longestCustom = 0;
+  for (UniquePtr<Token> const& custom : mCustomTokens) {
+    if (IsCustom(mCursor, *custom, &longestCustom)) {
+      aToken = *custom;
+      return mCursor + custom->mCustom.Length();
+    }
+  }
+
+  if (!mInputFinished && available < longestCustom) {
+    // Not enough data to deterministically decide.
+    return mCursor;
+  }
+
+  nsACString::const_char_iterator next = mCursor;
+
+  if (mMode == Mode::CUSTOM_ONLY) {
+    // We have to do a brute-force search for all of the enabled custom
+    // tokens.
+    while (next < mEnd) {
+      ++next;
+      for (UniquePtr<Token> const& custom : mCustomTokens) {
+        if (IsCustom(next, *custom)) {
+          aToken = Token::Raw();
+          return next;
+        }
+      }
+    }
+
+    if (mInputFinished) {
+      // End of the data reached.
+      aToken = Token::Raw();
+      return next;
+    }
+
+    if (longestCustom < available && available > mMinRawDelivery) {
+      // We can return some data w/o waiting for either a custom token
+      // or call to FinishData() when we leave the tail where all the
+      // custom tokens potentially fit, so we can't lose only partially
+      // delivered tokens.  This preserves reasonable granularity.
+      aToken = Token::Raw();
+      return mEnd - longestCustom + 1;
+    }
+
+    // Not enough data to deterministically decide.
+    return mCursor;
+  }
+
+  enum State {
+    PARSE_INTEGER,
+    PARSE_WORD,
+    PARSE_CRLF,
+    PARSE_LF,
+    PARSE_WS,
+    PARSE_CHAR,
+  } state;
+
+  if (IsWordFirst(*next)) {
+    state = PARSE_WORD;
+  } else if (IsNumber(*next)) {
+    state = PARSE_INTEGER;
+  } else if (strchr(mWhitespaces, *next)) { // not UTF-8 friendly?
+    state = PARSE_WS;
+  } else if (*next == '\r') {
+    state = PARSE_CRLF;
+  } else if (*next == '\n') {
+    state = PARSE_LF;
+  } else {
+    state = PARSE_CHAR;
+  }
+
+  mozilla::CheckedUint64 resultingNumber = 0;
+
+  while (next < mEnd) {
+    switch (state) {
+    case PARSE_INTEGER:
+      // Keep it simple for now
+      resultingNumber *= 10;
+      resultingNumber += static_cast<uint64_t>(*next - '0');
+
+      ++next;
+      if (IsPending(next)) {
+        break;
+      }
+      if (IsEnd(next) || !IsNumber(*next)) {
+        if (!resultingNumber.isValid()) {
+          aToken = Token::Error();
+        } else {
+          aToken = Token::Number(resultingNumber.value());
+        }
+        return next;
+      }
+      break;
+
+    case PARSE_WORD:
+      ++next;
+      if (IsPending(next)) {
+        break;
+      }
+      if (IsEnd(next) || !IsWord(*next)) {
+        aToken = Token::Word(Substring(mCursor, next));
+        return next;
+      }
+      break;
+
+    case PARSE_CRLF:
+      ++next;
+      if (IsPending(next)) {
+        break;
+      }
+      if (!IsEnd(next) && *next == '\n') { // LF is optional
+        ++next;
+      }
+      aToken = Token::NewLine();
+      return next;
+
+    case PARSE_LF:
+      ++next;
+      aToken = Token::NewLine();
+      return next;
+
+    case PARSE_WS:
+      ++next;
+      aToken = Token::Whitespace();
+      return next;
+
+    case PARSE_CHAR:
+      ++next;
+      aToken = Token::Char(*mCursor);
+      return next;
+    } // switch (state)
+  } // while (next < end)
+
+  MOZ_ASSERT(!mInputFinished);
+  return mCursor;
+}
+
+bool
+TokenizerBase::IsEnd(const nsACString::const_char_iterator& caret) const
+{
+  return caret == mEnd;
+}
+
+bool
+TokenizerBase::IsPending(const nsACString::const_char_iterator& caret) const
+{
+  return IsEnd(caret) && !mInputFinished;
+}
+
+bool
+TokenizerBase::IsWordFirst(const char aInput) const
+{
+  // TODO: make this fully work with unicode
+  return (ToLowerCase(static_cast<uint32_t>(aInput)) !=
+          ToUpperCase(static_cast<uint32_t>(aInput))) ||
+          '_' == aInput ||
+          (mAdditionalWordChars ? !!strchr(mAdditionalWordChars, aInput) : false);
+}
+
+bool
+TokenizerBase::IsWord(const char aInput) const
+{
+  return IsWordFirst(aInput) || IsNumber(aInput);
+}
+
+bool
+TokenizerBase::IsNumber(const char aInput) const
+{
+  // TODO: are there unicode numbers?
+  return aInput >= '0' && aInput <= '9';
+}
+
+bool
+TokenizerBase::IsCustom(const nsACString::const_char_iterator & caret,
+                        const Token & aCustomToken,
+                        uint32_t * aLongest) const
+{
+  MOZ_ASSERT(aCustomToken.mType > TOKEN_CUSTOM0);
+  if (!aCustomToken.mCustomEnabled) {
+    return false;
+  }
+
+  if (aLongest) {
+    *aLongest = std::max(*aLongest, aCustomToken.mCustom.Length());
+  }
+
+  uint32_t inputLength = mEnd - caret;
+  if (aCustomToken.mCustom.Length() > inputLength) {
+    return false;
+  }
+
+  nsDependentCSubstring inputFragment(caret, aCustomToken.mCustom.Length());
+  if (aCustomToken.mCustomCaseInsensitivity == CASE_INSENSITIVE) {
+    return inputFragment.Equals(aCustomToken.mCustom, nsCaseInsensitiveUTF8StringComparator());
+  }
+  return inputFragment.Equals(aCustomToken.mCustom);
+}
+
+void TokenizerBase::AssignFragment(Token& aToken,
+                                   nsACString::const_char_iterator begin,
+                                   nsACString::const_char_iterator end)
+{
+  aToken.AssignFragment(begin, end);
+}
+
+// TokenizerBase::Token
+
+TokenizerBase::Token::Token()
+  : mType(TOKEN_UNKNOWN)
+  , mChar(0)
+  , mInteger(0)
+  , mCustomCaseInsensitivity(CASE_SENSITIVE)
+  , mCustomEnabled(false)
+{
+}
+
+TokenizerBase::Token::Token(const Token& aOther)
+  : mType(aOther.mType)
+  , mCustom(aOther.mCustom)
+  , mChar(aOther.mChar)
+  , mInteger(aOther.mInteger)
+  , mCustomCaseInsensitivity(aOther.mCustomCaseInsensitivity)
+  , mCustomEnabled(aOther.mCustomEnabled)
+{
+  if (mType == TOKEN_WORD || mType > TOKEN_CUSTOM0) {
+    mWord.Rebind(aOther.mWord.BeginReading(), aOther.mWord.Length());
+  }
+}
+
+TokenizerBase::Token&
+TokenizerBase::Token::operator=(const Token& aOther)
+{
+  mType = aOther.mType;
+  mCustom = aOther.mCustom;
+  mChar = aOther.mChar;
+  mWord.Rebind(aOther.mWord.BeginReading(), aOther.mWord.Length());
+  mInteger = aOther.mInteger;
+  mCustomCaseInsensitivity = aOther.mCustomCaseInsensitivity;
+  mCustomEnabled = aOther.mCustomEnabled;
+  return *this;
+}
+
+void
+TokenizerBase::Token::AssignFragment(nsACString::const_char_iterator begin,
+                                     nsACString::const_char_iterator end)
+{
+  mFragment.Rebind(begin, end - begin);
+}
+
+// static
+TokenizerBase::Token
+TokenizerBase::Token::Raw()
+{
+  Token t;
+  t.mType = TOKEN_RAW;
+  return t;
+}
+
+// static
+TokenizerBase::Token
+TokenizerBase::Token::Word(const nsACString& aValue)
+{
+  Token t;
+  t.mType = TOKEN_WORD;
+  t.mWord.Rebind(aValue.BeginReading(), aValue.Length());
+  return t;
+}
+
+// static
+TokenizerBase::Token
+TokenizerBase::Token::Char(const char aValue)
+{
+  Token t;
+  t.mType = TOKEN_CHAR;
+  t.mChar = aValue;
+  return t;
+}
+
+// static
+TokenizerBase::Token
+TokenizerBase::Token::Number(const uint64_t aValue)
+{
+  Token t;
+  t.mType = TOKEN_INTEGER;
+  t.mInteger = aValue;
+  return t;
+}
+
+// static
+TokenizerBase::Token
+TokenizerBase::Token::Whitespace()
+{
+  Token t;
+  t.mType = TOKEN_WS;
+  t.mChar = '\0';
+  return t;
+}
+
+// static
+TokenizerBase::Token
+TokenizerBase::Token::NewLine()
+{
+  Token t;
+  t.mType = TOKEN_EOL;
+  return t;
+}
+
+// static
+TokenizerBase::Token
+TokenizerBase::Token::EndOfFile()
+{
+  Token t;
+  t.mType = TOKEN_EOF;
+  return t;
+}
+
+// static
+TokenizerBase::Token
+TokenizerBase::Token::Error()
+{
+  Token t;
+  t.mType = TOKEN_ERROR;
+  return t;
+}
+
+bool
+TokenizerBase::Token::Equals(const Token& aOther) const
+{
+  if (mType != aOther.mType) {
+    return false;
+  }
+
+  switch (mType) {
+  case TOKEN_INTEGER:
+    return AsInteger() == aOther.AsInteger();
+  case TOKEN_WORD:
+    return AsString() == aOther.AsString();
+  case TOKEN_CHAR:
+    return AsChar() == aOther.AsChar();
+  default:
+    return true;
+  }
+}
+
+char
+TokenizerBase::Token::AsChar() const
+{
+  MOZ_ASSERT(mType == TOKEN_CHAR || mType == TOKEN_WS);
+  return mChar;
+}
+
+nsDependentCSubstring
+TokenizerBase::Token::AsString() const
+{
+  MOZ_ASSERT(mType == TOKEN_WORD);
+  return mWord;
+}
+
+uint64_t
+TokenizerBase::Token::AsInteger() const
+{
+  MOZ_ASSERT(mType == TOKEN_INTEGER);
+  return mInteger;
+}
+
+} // mozilla
diff --git a/xpcom/ds/Tokenizer.h b/xpcom/ds/Tokenizer.h
new file mode 100644
index 000000000..b4aad9ed9
--- /dev/null
+++ b/xpcom/ds/Tokenizer.h
@@ -0,0 +1,446 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef Tokenizer_h__
+#define Tokenizer_h__
+
+#include "nsString.h"
+#include "mozilla/CheckedInt.h"
+#include "mozilla/UniquePtr.h"
+#include "nsTArray.h"
+
+namespace mozilla {
+
+class TokenizerBase
+{
+public:
+  /**
+   * The analyzer works with elements in the input cut to a sequence of token
+   * where each token has an elementary type
+   */
+  enum TokenType : uint32_t
+  {
+    TOKEN_UNKNOWN,
+    TOKEN_RAW,
+    TOKEN_ERROR,
+    TOKEN_INTEGER,
+    TOKEN_WORD,
+    TOKEN_CHAR,
+    TOKEN_WS,
+    TOKEN_EOL,
+    TOKEN_EOF,
+    TOKEN_CUSTOM0 = 1000
+  };
+
+  enum ECaseSensitivity
+  {
+    CASE_SENSITIVE,
+    CASE_INSENSITIVE
+  };
+
+  /**
+   * Class holding the type and the value of a token.  It can be manually created
+   * to allow checks against it via methods of Tokenizer or are results of some of
+   * the Tokenizer's methods.
+   */
+  class Token
+  {
+    TokenType mType;
+    nsDependentCSubstring mWord;
+    nsCString mCustom;
+    char mChar;
+    uint64_t mInteger;
+    ECaseSensitivity mCustomCaseInsensitivity;
+    bool mCustomEnabled;
+
+    // If this token is a result of the parsing process, this member is referencing
+    // a sub-string in the input buffer.  If this is externally created Token this
+    // member is left an empty string.
+    nsDependentCSubstring mFragment;
+
+    friend class TokenizerBase;
+    void AssignFragment(nsACString::const_char_iterator begin,
+                        nsACString::const_char_iterator end);
+
+    static Token Raw();
+
+  public:
+    Token();
+    Token(const Token& aOther);
+    Token& operator=(const Token& aOther);
+
+    // Static constructors of tokens by type and value
+    static Token Word(const nsACString& aWord);
+    static Token Char(const char aChar);
+    static Token Number(const uint64_t aNumber);
+    static Token Whitespace();
+    static Token NewLine();
+    static Token EndOfFile();
+    static Token Error();
+
+    // Compares the two tokens, type must be identical and value
+    // of one of the tokens must be 'any' or equal.
+    bool Equals(const Token& aOther) const;
+
+    TokenType Type() const { return mType; }
+    char AsChar() const;
+    nsDependentCSubstring AsString() const;
+    uint64_t AsInteger() const;
+
+    nsDependentCSubstring Fragment() const { return mFragment; }
+  };
+
+  /**
+   * Consumers may register a custom string that, when found in the input, is considered
+   * a token and returned by Next*() and accepted by Check*() methods.
+   * AddCustomToken() returns a reference to a token that can then be comapred using
+   * Token::Equals() againts the output from Next*() or be passed to Check*().
+   */
+  Token AddCustomToken(const nsACString& aValue, ECaseSensitivity aCaseInsensitivity, bool aEnabled = true);
+  template <uint32_t N>
+  Token AddCustomToken(const char(&aValue)[N], ECaseSensitivity aCaseInsensitivity, bool aEnabled = true)
+  {
+    return AddCustomToken(nsDependentCSubstring(aValue, N - 1), aCaseInsensitivity, aEnabled);
+  }
+  void RemoveCustomToken(Token& aToken);
+  /**
+   * Only applies to a custom type of a Token (see AddCustomToken above.)
+   * This turns on and off token recognition.  When a custom token is disabled,
+   * it's ignored as never added as a custom token.
+   */
+  void EnableCustomToken(Token const& aToken, bool aEnable);
+
+  /**
+   * Mode of tokenization.
+   * FULL tokenization, the default, recognizes built-in tokens and any custom tokens,
+   * if added.
+   * CUSTOM_ONLY will only recognize custom tokens, the rest is seen as 'raw'.
+   * This mode can be understood as a 'binary' mode.
+   */
+  enum class Mode
+  {
+    FULL,
+    CUSTOM_ONLY
+  };
+  void SetTokenizingMode(Mode aMode);
+
+  /**
+   * Return false iff the last Check*() call has returned false or when we've read past
+   * the end of the input string.
+   */
+  MOZ_MUST_USE bool HasFailed() const;
+
+protected:
+  explicit TokenizerBase(const char* aWhitespaces = nullptr,
+                         const char* aAdditionalWordChars = nullptr);
+
+  // false if we have already read the EOF token.
+  bool HasInput() const;
+  // Main parsing function, it doesn't shift the read cursor, just returns the next
+  // token position.
+  nsACString::const_char_iterator Parse(Token& aToken) const;
+  // Is read cursor at the end?
+  bool IsEnd(const nsACString::const_char_iterator& caret) const;
+  // True, when we are at the end of the input data, but it has not been marked
+  // as complete yet.  In that case we cannot proceed with providing a multi-char token.
+  bool IsPending(const nsACString::const_char_iterator & caret) const;
+  // Is read cursor on a character that is a word start?
+  bool IsWordFirst(const char aInput) const;
+  // Is read cursor on a character that is an in-word letter?
+  bool IsWord(const char aInput) const;
+  // Is read cursor on a character that is a valid number?
+  // TODO - support multiple radix
+  bool IsNumber(const char aInput) const;
+  // Is equal to the given custom token?
+  bool IsCustom(const nsACString::const_char_iterator& caret,
+                const Token& aCustomToken, uint32_t* aLongest = nullptr) const;
+
+  // Friendly helper to assign a fragment on a Token
+  static void AssignFragment(Token& aToken,
+                             nsACString::const_char_iterator begin,
+                             nsACString::const_char_iterator end);
+
+  // true iff we have already read the EOF token
+  bool mPastEof;
+  // true iff the last Check*() call has returned false, reverts to true on Rollback() call
+  bool mHasFailed;
+  // true if the input string is final (finished), false when we expect more data
+  // yet to be fed to the tokenizer (see IncrementalTokenizer derived class).
+  bool mInputFinished;
+  // custom only vs full tokenizing mode, see the Parse() method
+  Mode mMode;
+  // minimal raw data chunked delivery during incremental feed
+  uint32_t mMinRawDelivery;
+
+  // Customizable list of whitespaces
+  const char* mWhitespaces;
+  // Additinal custom word characters
+  const char* mAdditionalWordChars;
+
+  // All these point to the original buffer passed to the constructor or to the incremental
+  // buffer after FeedInput.
+  nsACString::const_char_iterator mCursor; // Position of the current (actually next to read) token start
+  nsACString::const_char_iterator mEnd; // End of the input position
+
+  // This is the list of tokens user has registered with AddCustomToken()
+  nsTArray<UniquePtr<Token>> mCustomTokens;
+  uint32_t mNextCustomTokenID;
+
+private:
+  TokenizerBase() = delete;
+  TokenizerBase(const TokenizerBase&) = delete;
+  TokenizerBase(TokenizerBase&&) = delete;
+  TokenizerBase(const TokenizerBase&&) = delete;
+  TokenizerBase &operator=(const TokenizerBase&) = delete;
+};
+
+/**
+ * This is a simple implementation of a lexical analyzer or maybe better
+ * called a tokenizer.  It doesn't allow any user dictionaries or
+ * user define token types.
+ *
+ * It is limited only to ASCII input for now. UTF-8 or any other input
+ * encoding must yet be implemented.
+ */
+class Tokenizer : public TokenizerBase
+{
+public:
+  /**
+   * @param aSource
+   *    The string to parse.
+   *    IMPORTANT NOTE: Tokenizer doesn't ensure the input string buffer lifetime.
+   *    It's up to the consumer to make sure the string's buffer outlives the Tokenizer!
+   * @param aWhitespaces
+   *    If non-null Tokenizer will use this custom set of whitespaces for CheckWhite()
+   *    and SkipWhites() calls.
+   *    By default the list consists of space and tab.
+   * @param aAdditionalWordChars
+   *    If non-null it will be added to the list of characters that consist a word.
+   *    This is useful when you want to accept e.g. '-' in HTTP headers.
+   *    By default a word character is consider any character for which upper case
+   *    is different from lower case.
+   *
+   * If there is an overlap between aWhitespaces and aAdditionalWordChars, the check for
+   * word characters is made first.
+   */
+  explicit Tokenizer(const nsACString& aSource,
+                     const char* aWhitespaces = nullptr,
+                     const char* aAdditionalWordChars = nullptr);
+  explicit Tokenizer(const char* aSource,
+                     const char* aWhitespaces = nullptr,
+                     const char* aAdditionalWordChars = nullptr);
+
+  /**
+   * When there is still anything to read from the input, tokenize it, store the token type
+   * and value to aToken result and shift the cursor past this just parsed token.  Each call
+   * to Next() reads another token from the input and shifts the cursor.
+   * Returns false if we have passed the end of the input.
+   */
+  MOZ_MUST_USE
+  bool Next(Token& aToken);
+
+  /**
+   * Parse the token on the input read cursor position, check its type is equal to aTokenType
+   * and if so, put it into aResult, shift the cursor and return true.  Otherwise, leave
+   * the input read cursor position intact and return false.
+   */
+  MOZ_MUST_USE
+  bool Check(const TokenType aTokenType, Token& aResult);
+  /**
+   * Same as above method, just compares both token type and token value passed in aToken.
+   * When both the type and the value equals, shift the cursor and return true.  Otherwise
+   * return false.
+   */
+  MOZ_MUST_USE
+  bool Check(const Token& aToken);
+
+  /**
+   * SkipWhites method (below) may also skip new line characters automatically.
+   */
+  enum WhiteSkipping {
+    /**
+     * SkipWhites will only skip what is defined as a white space (default).
+     */
+    DONT_INCLUDE_NEW_LINE = 0,
+    /**
+     * SkipWhites will skip definited white spaces as well as new lines
+     * automatically.
+     */
+    INCLUDE_NEW_LINE = 1
+  };
+
+  /**
+   * Skips any occurence of whitespaces specified in mWhitespaces member,
+   * optionally skip also new lines.
+   */
+  void SkipWhites(WhiteSkipping aIncludeNewLines = DONT_INCLUDE_NEW_LINE);
+
+  /**
+   * Skips all tokens until the given one is found or EOF is hit.  The token
+   * or EOF are next to read.
+   */
+  void SkipUntil(Token const& aToken);
+
+  // These are mostly shortcuts for the Check() methods above.
+
+  /**
+   * Check whitespace character is present.
+   */
+  MOZ_MUST_USE
+  bool CheckWhite() { return Check(Token::Whitespace()); }
+  /**
+   * Check there is a single character on the read cursor position.  If so, shift the read
+   * cursor position and return true.  Otherwise false.
+   */
+  MOZ_MUST_USE
+  bool CheckChar(const char aChar) { return Check(Token::Char(aChar)); }
+  /**
+   * This is a customizable version of CheckChar.  aClassifier is a function called with
+   * value of the character on the current input read position.  If this user function
+   * returns true, read cursor is shifted and true returned.  Otherwise false.
+   * The user classifiction function is not called when we are at or past the end and
+   * false is immediately returned.
+   */
+  MOZ_MUST_USE
+  bool CheckChar(bool (*aClassifier)(const char aChar));
+  /**
+   * Check for a whole expected word.
+   */
+  MOZ_MUST_USE
+  bool CheckWord(const nsACString& aWord) { return Check(Token::Word(aWord)); }
+  /**
+   * Shortcut for literal const word check with compile time length calculation.
+   */
+  template <uint32_t N>
+  MOZ_MUST_USE
+  bool CheckWord(const char (&aWord)[N]) { return Check(Token::Word(nsDependentCString(aWord, N - 1))); }
+  /**
+   * Checks \r, \n or \r\n.
+   */
+  MOZ_MUST_USE
+  bool CheckEOL() { return Check(Token::NewLine()); }
+  /**
+   * Checks we are at the end of the input string reading.  If so, shift past the end
+   * and returns true.  Otherwise does nothing and returns false.
+   */
+  MOZ_MUST_USE
+  bool CheckEOF() { return Check(Token::EndOfFile()); }
+
+  /**
+   * These are shortcuts to obtain the value immediately when the token type matches.
+   */
+  MOZ_MUST_USE bool ReadChar(char* aValue);
+  MOZ_MUST_USE bool ReadChar(bool (*aClassifier)(const char aChar),
+                             char* aValue);
+  MOZ_MUST_USE bool ReadWord(nsACString& aValue);
+  MOZ_MUST_USE bool ReadWord(nsDependentCSubstring& aValue);
+
+  /**
+   * This is an integer read helper.  It returns false and doesn't move the read
+   * cursor when any of the following happens:
+   *  - the token at the read cursor is not an integer
+   *  - the final number doesn't fit the T type
+   * Otherwise true is returned, aValue is filled with the integral number
+   * and the cursor is moved forward.
+   */
+  template <typename T>
+  MOZ_MUST_USE bool ReadInteger(T* aValue)
+  {
+    MOZ_RELEASE_ASSERT(aValue);
+
+    nsACString::const_char_iterator rollback = mRollback;
+    nsACString::const_char_iterator cursor = mCursor;
+    Token t;
+    if (!Check(TOKEN_INTEGER, t)) {
+      return false;
+    }
+
+    mozilla::CheckedInt<T> checked(t.AsInteger());
+    if (!checked.isValid()) {
+      // Move to a state as if Check() call has failed
+      mRollback = rollback;
+      mCursor = cursor;
+      mHasFailed = true;
+      return false;
+    }
+
+    *aValue = checked.value();
+    return true;
+  }
+
+  /**
+   * Returns the read cursor position back as it was before the last call of any parsing
+   * method of Tokenizer (Next, Check*, Skip*, Read*) so that the last operation
+   * can be repeated.
+   * Rollback cannot be used multiple times, it only reverts the last successfull parse
+   * operation.  It also cannot be used before any parsing operation has been called
+   * on the Tokenizer.
+   */
+  void Rollback();
+
+  /**
+   * Record() and Claim() are collecting the input as it is being parsed to obtain
+   * a substring between particular syntax bounderies defined by any recursive
+   * descent parser or simple parser the Tokenizer is used to read the input for.
+   * Inlucsion of a token that has just been parsed can be controlled using an arguemnt.
+   */
+  enum ClaimInclusion {
+    /**
+     * Include resulting (or passed) token of the last lexical analyzer operation in the result.
+     */
+    INCLUDE_LAST,
+    /**
+     * Do not include it.
+     */
+    EXCLUDE_LAST
+  };
+
+  /**
+   * Start the process of recording.  Based on aInclude value the begining of the recorded
+   * sub-string is at the current position (EXCLUDE_LAST) or at the position before the last
+   * parsed token (INCLUDE_LAST).
+   */
+  void Record(ClaimInclusion aInclude = EXCLUDE_LAST);
+  /**
+   * Claim result of the record started with Record() call before.  Depending on aInclude
+   * the ending of the sub-string result includes or excludes the last parsed or checked
+   * token.
+   */
+  void Claim(nsACString& aResult, ClaimInclusion aInclude = EXCLUDE_LAST);
+  void Claim(nsDependentCSubstring& aResult, ClaimInclusion aInclude = EXCLUDE_LAST);
+
+  /**
+   * If aToken is found, aResult is set to the substring between the current
+   * position and the position of aToken, potentially including aToken depending
+   * on aInclude.
+   * If aToken isn't found aResult is set to the substring between the current
+   * position and the end of the string.
+   * If aToken is found, the method returns true. Otherwise it returns false.
+   *
+   * Calling Rollback() after ReadUntil() will return the read cursor to the
+   * position it had before ReadUntil was called.
+   */
+  MOZ_MUST_USE bool ReadUntil(Token const& aToken, nsDependentCSubstring& aResult,
+                              ClaimInclusion aInclude = EXCLUDE_LAST);
+  MOZ_MUST_USE bool ReadUntil(Token const& aToken, nsACString& aResult,
+                              ClaimInclusion aInclude = EXCLUDE_LAST);
+
+protected:
+  // All these point to the original buffer passed to the Tokenizer's constructor
+  nsACString::const_char_iterator mRecord; // Position where the recorded sub-string for Claim() is
+  nsACString::const_char_iterator mRollback; // Position of the previous token start
+
+private:
+  Tokenizer() = delete;
+  Tokenizer(const Tokenizer&) = delete;
+  Tokenizer(Tokenizer&&) = delete;
+  Tokenizer(const Tokenizer&&) = delete;
+  Tokenizer &operator=(const Tokenizer&) = delete;
+};
+
+} // mozilla
+
+#endif // Tokenizer_h__
diff --git a/xpcom/ds/moz.build b/xpcom/ds/moz.build
new file mode 100644
index 000000000..e12f1c3dd
--- /dev/null
+++ b/xpcom/ds/moz.build
@@ -0,0 +1,105 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+XPIDL_SOURCES += [
+    'nsIArray.idl',
+    'nsIArrayExtensions.idl',
+    'nsIAtom.idl',
+    'nsIAtomService.idl',
+    'nsICollection.idl',
+    'nsIEnumerator.idl',
+    'nsIHashable.idl',
+    'nsIINIParser.idl',
+    'nsIMutableArray.idl',
+    'nsIObserver.idl',
+    'nsIObserverService.idl',
+    'nsIPersistentProperties2.idl',
+    'nsIProperties.idl',
+    'nsIProperty.idl',
+    'nsIPropertyBag.idl',
+    'nsIPropertyBag2.idl',
+    'nsISerializable.idl',
+    'nsISimpleEnumerator.idl',
+    'nsIStringEnumerator.idl',
+    'nsISupportsArray.idl',
+    'nsISupportsIterators.idl',
+    'nsISupportsPrimitives.idl',
+    'nsIVariant.idl',
+    'nsIWritablePropertyBag.idl',
+    'nsIWritablePropertyBag2.idl',
+]
+
+if CONFIG['OS_ARCH'] == 'WINNT':
+    XPIDL_SOURCES += [
+        'nsIWindowsRegKey.idl',
+    ]
+    EXPORTS += ['nsWindowsRegKey.h']
+    SOURCES += [
+        'nsWindowsRegKey.cpp'
+    ]
+
+XPIDL_MODULE = 'xpcom_ds'
+
+EXPORTS += [
+    'nsArray.h',
+    'nsAtomService.h',
+    'nsCharSeparatedTokenizer.h',
+    'nsCheapSets.h',
+    'nsCRT.h',
+    'nsExpirationTracker.h',
+    'nsHashPropertyBag.h',
+    'nsMathUtils.h',
+    'nsStaticAtom.h',
+    'nsStaticNameTable.h',
+    'nsStringEnumerator.h',
+    'nsSupportsArray.h',
+    'nsSupportsPrimitives.h',
+    'nsVariant.h',
+    'nsWhitespaceTokenizer.h',
+]
+
+EXPORTS.mozilla += [
+    'IncrementalTokenizer.h',
+    'StickyTimeDuration.h',
+    'Tokenizer.h',
+]
+
+UNIFIED_SOURCES += [
+    'IncrementalTokenizer.cpp',
+    'nsArray.cpp',
+    'nsAtomService.cpp',
+    'nsAtomTable.cpp',
+    'nsCRT.cpp',
+    'nsHashPropertyBag.cpp',
+    'nsINIParserImpl.cpp',
+    'nsObserverList.cpp',
+    'nsObserverService.cpp',
+    'nsProperties.cpp',
+    'nsStringEnumerator.cpp',
+    'nsSupportsArray.cpp',
+    'nsSupportsArrayEnumerator.cpp',
+    'nsSupportsPrimitives.cpp',
+    'nsVariant.cpp',
+    'Tokenizer.cpp',
+]
+
+# These two files cannot be built in unified mode because they use the
+# PL_ARENA_CONST_ALIGN_MASK macro with plarena.h.
+SOURCES += [
+    'nsPersistentProperties.cpp',
+    'nsStaticNameTable.cpp',
+]
+
+EXTRA_COMPONENTS += [
+    'nsINIProcessor.js',
+    'nsINIProcessor.manifest',
+]
+
+LOCAL_INCLUDES += [
+    '../io',
+]
+
+FINAL_LIBRARY = 'xul'
diff --git a/xpcom/ds/nsArray.cpp b/xpcom/ds/nsArray.cpp
new file mode 100644
index 000000000..d137a14a5
--- /dev/null
+++ b/xpcom/ds/nsArray.cpp
@@ -0,0 +1,242 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsArray.h"
+#include "nsArrayEnumerator.h"
+#include "nsIWeakReference.h"
+#include "nsIWeakReferenceUtils.h"
+#include "nsThreadUtils.h"
+
+// used by IndexOf()
+struct MOZ_STACK_CLASS findIndexOfClosure
+{
+  // This is only used for pointer comparison, so we can just use a void*.
+  void* targetElement;
+  uint32_t startIndex;
+  uint32_t resultIndex;
+};
+
+static bool FindElementCallback(void* aElement, void* aClosure);
+
+NS_INTERFACE_MAP_BEGIN(nsArray)
+  NS_INTERFACE_MAP_ENTRY(nsIArray)
+  NS_INTERFACE_MAP_ENTRY(nsIArrayExtensions)
+  NS_INTERFACE_MAP_ENTRY(nsIMutableArray)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIMutableArray)
+NS_INTERFACE_MAP_END
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsArrayCC)
+  NS_INTERFACE_MAP_ENTRY(nsIArray)
+  NS_INTERFACE_MAP_ENTRY(nsIArrayExtensions)
+  NS_INTERFACE_MAP_ENTRY(nsIMutableArray)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIMutableArray)
+NS_INTERFACE_MAP_END
+
+nsArrayBase::~nsArrayBase()
+{
+  Clear();
+}
+
+
+NS_IMPL_ADDREF(nsArray)
+NS_IMPL_RELEASE(nsArray)
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(nsArrayCC)
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(nsArrayCC)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(nsArrayCC)
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsArrayCC)
+  tmp->Clear();
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsArrayCC)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mArray)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMETHODIMP
+nsArrayBase::GetLength(uint32_t* aLength)
+{
+  *aLength = mArray.Count();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsArrayBase::QueryElementAt(uint32_t aIndex,
+                            const nsIID& aIID,
+                            void** aResult)
+{
+  nsISupports* obj = mArray.SafeObjectAt(aIndex);
+  if (!obj) {
+    return NS_ERROR_ILLEGAL_VALUE;
+  }
+
+  // no need to worry about a leak here, because SafeObjectAt()
+  // doesn't addref its result
+  return obj->QueryInterface(aIID, aResult);
+}
+
+NS_IMETHODIMP
+nsArrayBase::IndexOf(uint32_t aStartIndex, nsISupports* aElement,
+                     uint32_t* aResult)
+{
+  // optimize for the common case by forwarding to mArray
+  if (aStartIndex == 0) {
+    uint32_t idx = mArray.IndexOf(aElement);
+    if (idx == UINT32_MAX) {
+      return NS_ERROR_FAILURE;
+    }
+
+    *aResult = idx;
+    return NS_OK;
+  }
+
+  findIndexOfClosure closure = { aElement, aStartIndex, 0 };
+  bool notFound = mArray.EnumerateForwards(FindElementCallback, &closure);
+  if (notFound) {
+    return NS_ERROR_FAILURE;
+  }
+
+  *aResult = closure.resultIndex;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsArrayBase::Enumerate(nsISimpleEnumerator** aResult)
+{
+  return NS_NewArrayEnumerator(aResult, static_cast<nsIArray*>(this));
+}
+
+// nsIMutableArray implementation
+
+NS_IMETHODIMP
+nsArrayBase::AppendElement(nsISupports* aElement, bool aWeak)
+{
+  bool result;
+  if (aWeak) {
+    nsCOMPtr<nsIWeakReference> elementRef = do_GetWeakReference(aElement);
+    NS_ASSERTION(elementRef,
+                 "AppendElement: Trying to use weak references on an object that doesn't support it");
+    if (!elementRef) {
+      return NS_ERROR_FAILURE;
+    }
+    result = mArray.AppendObject(elementRef);
+  }
+
+  else {
+    // add the object directly
+    result = mArray.AppendObject(aElement);
+  }
+  return result ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsArrayBase::RemoveElementAt(uint32_t aIndex)
+{
+  bool result = mArray.RemoveObjectAt(aIndex);
+  return result ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsArrayBase::InsertElementAt(nsISupports* aElement, uint32_t aIndex, bool aWeak)
+{
+  nsCOMPtr<nsISupports> elementRef;
+  if (aWeak) {
+    elementRef = do_GetWeakReference(aElement);
+    NS_ASSERTION(elementRef,
+                 "InsertElementAt: Trying to use weak references on an object that doesn't support it");
+    if (!elementRef) {
+      return NS_ERROR_FAILURE;
+    }
+  } else {
+    elementRef = aElement;
+  }
+  bool result = mArray.InsertObjectAt(elementRef, aIndex);
+  return result ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsArrayBase::ReplaceElementAt(nsISupports* aElement, uint32_t aIndex, bool aWeak)
+{
+  nsCOMPtr<nsISupports> elementRef;
+  if (aWeak) {
+    elementRef = do_GetWeakReference(aElement);
+    NS_ASSERTION(elementRef,
+                 "ReplaceElementAt: Trying to use weak references on an object that doesn't support it");
+    if (!elementRef) {
+      return NS_ERROR_FAILURE;
+    }
+  } else {
+    elementRef = aElement;
+  }
+  mArray.ReplaceObjectAt(elementRef, aIndex);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsArrayBase::Clear()
+{
+  mArray.Clear();
+  return NS_OK;
+}
+
+// nsIArrayExtensions implementation.
+
+NS_IMETHODIMP
+nsArrayBase::Count(uint32_t* aResult)
+{
+  return GetLength(aResult);
+}
+
+NS_IMETHODIMP
+nsArrayBase::GetElementAt(uint32_t aIndex, nsISupports** aResult)
+{
+  nsCOMPtr<nsISupports> obj = mArray.SafeObjectAt(aIndex);
+  obj.forget(aResult);
+  return NS_OK;
+}
+
+//
+// static helper routines
+//
+bool
+FindElementCallback(void* aElement, void* aClosure)
+{
+  findIndexOfClosure* closure = static_cast<findIndexOfClosure*>(aClosure);
+  nsISupports* element = static_cast<nsISupports*>(aElement);
+
+  // don't start searching until we're past the startIndex
+  if (closure->resultIndex >= closure->startIndex &&
+      element == closure->targetElement) {
+    return false;    // stop! We found it
+  }
+  closure->resultIndex++;
+
+  return true;
+}
+
+nsresult
+nsArrayBase::XPCOMConstructor(nsISupports* aOuter, const nsIID& aIID,
+                              void** aResult)
+{
+  if (aOuter) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+
+  nsCOMPtr<nsIMutableArray> inst = Create();
+  return inst->QueryInterface(aIID, aResult);
+}
+
+already_AddRefed<nsIMutableArray>
+nsArrayBase::Create()
+{
+  nsCOMPtr<nsIMutableArray> inst;
+  if (NS_IsMainThread()) {
+    inst = new nsArrayCC;
+  } else {
+    inst = new nsArray;
+  }
+  return inst.forget();
+}
diff --git a/xpcom/ds/nsArray.h b/xpcom/ds/nsArray.h
new file mode 100644
index 000000000..0cda23487
--- /dev/null
+++ b/xpcom/ds/nsArray.h
@@ -0,0 +1,76 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsArray_h__
+#define nsArray_h__
+
+#include "nsIArrayExtensions.h"
+#include "nsIMutableArray.h"
+#include "nsCOMArray.h"
+#include "nsCOMPtr.h"
+#include "nsCycleCollectionParticipant.h"
+#include "mozilla/Attributes.h"
+
+// {35C66FD1-95E9-4e0a-80C5-C3BD2B375481}
+#define NS_ARRAY_CID \
+{ 0x35c66fd1, 0x95e9, 0x4e0a, \
+  { 0x80, 0xc5, 0xc3, 0xbd, 0x2b, 0x37, 0x54, 0x81 } }
+
+// nsArray without any refcounting declarations
+class nsArrayBase : public nsIMutableArray
+{
+public:
+  NS_DECL_NSIARRAY
+  NS_DECL_NSIARRAYEXTENSIONS
+  NS_DECL_NSIMUTABLEARRAY
+
+  /* Both of these factory functions create a cycle-collectable array
+     on the main thread and a non-cycle-collectable array on other
+     threads.  */
+  static already_AddRefed<nsIMutableArray> Create();
+  /* Only for the benefit of the XPCOM module system, use Create()
+     instead.  */
+  static nsresult XPCOMConstructor(nsISupports* aOuter, const nsIID& aIID,
+                                   void** aResult);
+protected:
+  nsArrayBase() {}
+  nsArrayBase(const nsArrayBase& aOther);
+  explicit nsArrayBase(const nsCOMArray_base& aBaseArray) : mArray(aBaseArray) {}
+  virtual ~nsArrayBase();
+
+  nsCOMArray_base mArray;
+};
+
+class nsArray final : public nsArrayBase
+{
+  friend class nsArrayBase;
+
+public:
+  NS_DECL_ISUPPORTS
+
+private:
+  nsArray() : nsArrayBase() {}
+  nsArray(const nsArray& aOther);
+  explicit nsArray(const nsCOMArray_base& aBaseArray) : nsArrayBase(aBaseArray) {}
+  ~nsArray() {}
+};
+
+class nsArrayCC final : public nsArrayBase
+{
+  friend class nsArrayBase;
+
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(nsArrayCC, nsIMutableArray)
+
+private:
+  nsArrayCC() : nsArrayBase() {}
+  nsArrayCC(const nsArrayCC& aOther);
+  explicit nsArrayCC(const nsCOMArray_base& aBaseArray) : nsArrayBase(aBaseArray) {}
+  ~nsArrayCC() {}
+};
+
+#endif
diff --git a/xpcom/ds/nsAtomService.cpp b/xpcom/ds/nsAtomService.cpp
new file mode 100644
index 000000000..7785ca2e4
--- /dev/null
+++ b/xpcom/ds/nsAtomService.cpp
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsAtomService.h"
+#include "nsIAtom.h"
+
+NS_IMPL_ISUPPORTS(nsAtomService, nsIAtomService)
+
+nsAtomService::nsAtomService()
+{
+}
+
+nsresult
+nsAtomService::GetAtom(const nsAString& aString, nsIAtom** aResult)
+{
+  *aResult = NS_Atomize(aString).take();
+  if (!*aResult) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  return NS_OK;
+}
diff --git a/xpcom/ds/nsAtomService.h b/xpcom/ds/nsAtomService.h
new file mode 100644
index 000000000..7a1bcf2cd
--- /dev/null
+++ b/xpcom/ds/nsAtomService.h
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __nsAtomService_h
+#define __nsAtomService_h
+
+#include "nsIAtomService.h"
+#include "mozilla/Attributes.h"
+
+class nsAtomService final : public nsIAtomService
+{
+public:
+  nsAtomService();
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  NS_DECL_NSIATOMSERVICE
+
+private:
+  ~nsAtomService() {}
+};
+
+#endif
diff --git a/xpcom/ds/nsAtomTable.cpp b/xpcom/ds/nsAtomTable.cpp
new file mode 100644
index 000000000..3dd3bd36c
--- /dev/null
+++ b/xpcom/ds/nsAtomTable.cpp
@@ -0,0 +1,736 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/HashFunctions.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/Sprintf.h"
+#include "mozilla/Unused.h"
+
+#include "nsAtomTable.h"
+#include "nsStaticAtom.h"
+#include "nsString.h"
+#include "nsCRT.h"
+#include "PLDHashTable.h"
+#include "prenv.h"
+#include "nsThreadUtils.h"
+#include "nsDataHashtable.h"
+#include "nsHashKeys.h"
+#include "nsAutoPtr.h"
+#include "nsUnicharUtils.h"
+#include "nsPrintfCString.h"
+
+// There are two kinds of atoms handled by this module.
+//
+// - DynamicAtom: the atom itself is heap allocated, as is the nsStringBuffer it
+//   points to. |gAtomTable| holds weak references to them DynamicAtoms. When
+//   the refcount of a DynamicAtom drops to zero, we increment a static counter.
+//   When that counter reaches a certain threshold, we iterate over the atom
+//   table, removing and deleting DynamicAtoms with refcount zero. This allows
+//   us to avoid acquiring the atom table lock during normal refcounting.
+//
+// - StaticAtom: the atom itself is heap allocated, but it points to a static
+//   nsStringBuffer. |gAtomTable| effectively owns StaticAtoms, because such
+//   atoms ignore all AddRef/Release calls, which ensures they stay alive until
+//   |gAtomTable| itself is destroyed whereupon they are explicitly deleted.
+//
+//   Note that gAtomTable is used on multiple threads, and callers must
+//   acquire gAtomTableLock before touching it.
+
+using namespace mozilla;
+
+//----------------------------------------------------------------------
+
+class CheckStaticAtomSizes
+{
+  CheckStaticAtomSizes()
+  {
+    static_assert((sizeof(nsFakeStringBuffer<1>().mRefCnt) ==
+                   sizeof(nsStringBuffer().mRefCount)) &&
+                  (sizeof(nsFakeStringBuffer<1>().mSize) ==
+                   sizeof(nsStringBuffer().mStorageSize)) &&
+                  (offsetof(nsFakeStringBuffer<1>, mRefCnt) ==
+                   offsetof(nsStringBuffer, mRefCount)) &&
+                  (offsetof(nsFakeStringBuffer<1>, mSize) ==
+                   offsetof(nsStringBuffer, mStorageSize)) &&
+                  (offsetof(nsFakeStringBuffer<1>, mStringData) ==
+                   sizeof(nsStringBuffer)),
+                  "mocked-up strings' representations should be compatible");
+  }
+};
+
+//----------------------------------------------------------------------
+
+static Atomic<uint32_t, ReleaseAcquire> gUnusedAtomCount(0);
+
+class DynamicAtom final : public nsIAtom
+{
+public:
+  static already_AddRefed<DynamicAtom> Create(const nsAString& aString, uint32_t aHash)
+  {
+    // The refcount is appropriately initialized in the constructor.
+    return dont_AddRef(new DynamicAtom(aString, aHash));
+  }
+
+  static void GCAtomTable();
+
+  enum class GCKind {
+    RegularOperation,
+    Shutdown,
+  };
+
+  static void GCAtomTableLocked(const MutexAutoLock& aProofOfLock,
+                                GCKind aKind);
+
+private:
+  DynamicAtom(const nsAString& aString, uint32_t aHash)
+    : mRefCnt(1)
+  {
+    mLength = aString.Length();
+    mIsStatic = false;
+    RefPtr<nsStringBuffer> buf = nsStringBuffer::FromString(aString);
+    if (buf) {
+      mString = static_cast<char16_t*>(buf->Data());
+    } else {
+      const size_t size = (mLength + 1) * sizeof(char16_t);
+      buf = nsStringBuffer::Alloc(size);
+      if (MOZ_UNLIKELY(!buf)) {
+        // We OOM because atom allocations should be small and it's hard to
+        // handle them more gracefully in a constructor.
+        NS_ABORT_OOM(size);
+      }
+      mString = static_cast<char16_t*>(buf->Data());
+      CopyUnicodeTo(aString, 0, mString, mLength);
+      mString[mLength] = char16_t(0);
+    }
+
+    mHash = aHash;
+    MOZ_ASSERT(mHash == HashString(mString, mLength));
+
+    NS_ASSERTION(mString[mLength] == char16_t(0), "null terminated");
+    NS_ASSERTION(buf && buf->StorageSize() >= (mLength + 1) * sizeof(char16_t),
+                 "enough storage");
+    NS_ASSERTION(Equals(aString), "correct data");
+
+    // Take ownership of buffer
+    mozilla::Unused << buf.forget();
+  }
+
+private:
+  // We don't need a virtual destructor because we always delete via a
+  // DynamicAtom* pointer (in GCAtomTable()), not an nsIAtom* pointer.
+  ~DynamicAtom();
+
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIATOM
+};
+
+class StaticAtom final : public nsIAtom
+{
+public:
+  StaticAtom(nsStringBuffer* aStringBuffer, uint32_t aLength, uint32_t aHash)
+  {
+    mLength = aLength;
+    mIsStatic = true;
+    mString = static_cast<char16_t*>(aStringBuffer->Data());
+    // Technically we could currently avoid doing this addref by instead making
+    // the static atom buffers have an initial refcount of 2.
+    aStringBuffer->AddRef();
+
+    mHash = aHash;
+    MOZ_ASSERT(mHash == HashString(mString, mLength));
+
+    MOZ_ASSERT(mString[mLength] == char16_t(0), "null terminated");
+    MOZ_ASSERT(aStringBuffer &&
+               aStringBuffer->StorageSize() == (mLength + 1) * sizeof(char16_t),
+               "correct storage");
+  }
+
+  // We don't need a virtual destructor because we always delete via a
+  // StaticAtom* pointer (in AtomTableClearEntry()), not an nsIAtom* pointer.
+  ~StaticAtom() {}
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIATOM
+};
+
+NS_IMPL_QUERY_INTERFACE(StaticAtom, nsIAtom)
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+StaticAtom::AddRef()
+{
+  return 2;
+}
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+StaticAtom::Release()
+{
+  return 1;
+}
+
+NS_IMETHODIMP
+DynamicAtom::ScriptableToString(nsAString& aBuf)
+{
+  nsStringBuffer::FromData(mString)->ToString(mLength, aBuf);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+StaticAtom::ScriptableToString(nsAString& aBuf)
+{
+  nsStringBuffer::FromData(mString)->ToString(mLength, aBuf);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+DynamicAtom::ToUTF8String(nsACString& aBuf)
+{
+  CopyUTF16toUTF8(nsDependentString(mString, mLength), aBuf);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+StaticAtom::ToUTF8String(nsACString& aBuf)
+{
+  CopyUTF16toUTF8(nsDependentString(mString, mLength), aBuf);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+DynamicAtom::ScriptableEquals(const nsAString& aString, bool* aResult)
+{
+  *aResult = aString.Equals(nsDependentString(mString, mLength));
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+StaticAtom::ScriptableEquals(const nsAString& aString, bool* aResult)
+{
+  *aResult = aString.Equals(nsDependentString(mString, mLength));
+  return NS_OK;
+}
+
+NS_IMETHODIMP_(size_t)
+DynamicAtom::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf)
+{
+  size_t n = aMallocSizeOf(this);
+  n += nsStringBuffer::FromData(mString)->SizeOfIncludingThisIfUnshared(
+         aMallocSizeOf);
+  return n;
+}
+
+NS_IMETHODIMP_(size_t)
+StaticAtom::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf)
+{
+  size_t n = aMallocSizeOf(this);
+  // Don't measure the string buffer pointed to by the StaticAtom because it's
+  // in static memory.
+  return n;
+}
+
+//----------------------------------------------------------------------
+
+/**
+ * The shared hash table for atom lookups.
+ *
+ * Callers must hold gAtomTableLock before manipulating the table.
+ */
+static PLDHashTable* gAtomTable;
+static Mutex* gAtomTableLock;
+
+struct AtomTableKey
+{
+  AtomTableKey(const char16_t* aUTF16String, uint32_t aLength, uint32_t aHash)
+    : mUTF16String(aUTF16String)
+    , mUTF8String(nullptr)
+    , mLength(aLength)
+    , mHash(aHash)
+  {
+    MOZ_ASSERT(mHash == HashString(mUTF16String, mLength));
+  }
+
+  AtomTableKey(const char* aUTF8String, uint32_t aLength, uint32_t aHash)
+    : mUTF16String(nullptr)
+    , mUTF8String(aUTF8String)
+    , mLength(aLength)
+    , mHash(aHash)
+  {
+    mozilla::DebugOnly<bool> err;
+    MOZ_ASSERT(aHash == HashUTF8AsUTF16(mUTF8String, mLength, &err));
+  }
+
+  AtomTableKey(const char16_t* aUTF16String, uint32_t aLength,
+               uint32_t* aHashOut)
+    : mUTF16String(aUTF16String)
+    , mUTF8String(nullptr)
+    , mLength(aLength)
+  {
+    mHash = HashString(mUTF16String, mLength);
+    *aHashOut = mHash;
+  }
+
+  AtomTableKey(const char* aUTF8String, uint32_t aLength, uint32_t* aHashOut)
+    : mUTF16String(nullptr)
+    , mUTF8String(aUTF8String)
+    , mLength(aLength)
+  {
+    bool err;
+    mHash = HashUTF8AsUTF16(mUTF8String, mLength, &err);
+    if (err) {
+      mUTF8String = nullptr;
+      mLength = 0;
+      mHash = 0;
+    }
+    *aHashOut = mHash;
+  }
+
+  const char16_t* mUTF16String;
+  const char* mUTF8String;
+  uint32_t mLength;
+  uint32_t mHash;
+};
+
+struct AtomTableEntry : public PLDHashEntryHdr
+{
+  // These references are either to DynamicAtoms, in which case they are
+  // non-owning, or they are to StaticAtoms, which aren't really refcounted.
+  // See the comment at the top of this file for more details.
+  nsIAtom* MOZ_NON_OWNING_REF mAtom;
+};
+
+static PLDHashNumber
+AtomTableGetHash(const void* aKey)
+{
+  const AtomTableKey* k = static_cast<const AtomTableKey*>(aKey);
+  return k->mHash;
+}
+
+static bool
+AtomTableMatchKey(const PLDHashEntryHdr* aEntry, const void* aKey)
+{
+  const AtomTableEntry* he = static_cast<const AtomTableEntry*>(aEntry);
+  const AtomTableKey* k = static_cast<const AtomTableKey*>(aKey);
+
+  if (k->mUTF8String) {
+    return
+      CompareUTF8toUTF16(nsDependentCSubstring(k->mUTF8String,
+                                               k->mUTF8String + k->mLength),
+                         nsDependentAtomString(he->mAtom)) == 0;
+  }
+
+  uint32_t length = he->mAtom->GetLength();
+  if (length != k->mLength) {
+    return false;
+  }
+
+  return memcmp(he->mAtom->GetUTF16String(),
+                k->mUTF16String, length * sizeof(char16_t)) == 0;
+}
+
+static void
+AtomTableClearEntry(PLDHashTable* aTable, PLDHashEntryHdr* aEntry)
+{
+  auto entry = static_cast<AtomTableEntry*>(aEntry);
+  nsIAtom* atom = entry->mAtom;
+  if (atom->IsStaticAtom()) {
+    // This case -- when the entry being cleared holds a StaticAtom -- only
+    // occurs when gAtomTable is destroyed, whereupon all StaticAtoms within it
+    // must be explicitly deleted. The cast is required because StaticAtom
+    // doesn't have a virtual destructor.
+    delete static_cast<StaticAtom*>(atom);
+  }
+}
+
+static void
+AtomTableInitEntry(PLDHashEntryHdr* aEntry, const void* aKey)
+{
+  static_cast<AtomTableEntry*>(aEntry)->mAtom = nullptr;
+}
+
+static const PLDHashTableOps AtomTableOps = {
+  AtomTableGetHash,
+  AtomTableMatchKey,
+  PLDHashTable::MoveEntryStub,
+  AtomTableClearEntry,
+  AtomTableInitEntry
+};
+
+//----------------------------------------------------------------------
+
+void
+DynamicAtom::GCAtomTable()
+{
+  MutexAutoLock lock(*gAtomTableLock);
+  GCAtomTableLocked(lock, GCKind::RegularOperation);
+}
+
+void
+DynamicAtom::GCAtomTableLocked(const MutexAutoLock& aProofOfLock,
+                               GCKind aKind)
+{
+  uint32_t removedCount = 0; // Use a non-atomic temporary for cheaper increments.
+  nsAutoCString nonZeroRefcountAtoms;
+  uint32_t nonZeroRefcountAtomsCount = 0;
+  for (auto i = gAtomTable->Iter(); !i.Done(); i.Next()) {
+    auto entry = static_cast<AtomTableEntry*>(i.Get());
+    if (entry->mAtom->IsStaticAtom()) {
+      continue;
+    }
+
+    auto atom = static_cast<DynamicAtom*>(entry->mAtom);
+    if (atom->mRefCnt == 0) {
+      i.Remove();
+      delete atom;
+      ++removedCount;
+    }
+#ifdef NS_FREE_PERMANENT_DATA
+    else if (aKind == GCKind::Shutdown && PR_GetEnv("XPCOM_MEM_BLOAT_LOG")) {
+      // Only report leaking atoms in leak-checking builds in a run
+      // where we are checking for leaks, during shutdown. If
+      // something is anomalous, then we'll assert later in this
+      // function.
+      nsAutoCString name;
+      atom->ToUTF8String(name);
+      if (nonZeroRefcountAtomsCount == 0) {
+        nonZeroRefcountAtoms = name;
+      } else if (nonZeroRefcountAtomsCount < 20) {
+        nonZeroRefcountAtoms += NS_LITERAL_CSTRING(",") + name;
+      } else if (nonZeroRefcountAtomsCount == 20) {
+        nonZeroRefcountAtoms += NS_LITERAL_CSTRING(",...");
+      }
+      nonZeroRefcountAtomsCount++;
+    }
+#endif
+
+  }
+  if (nonZeroRefcountAtomsCount) {
+    nsPrintfCString msg("%d dynamic atom(s) with non-zero refcount: %s",
+                        nonZeroRefcountAtomsCount, nonZeroRefcountAtoms.get());
+    NS_ASSERTION(nonZeroRefcountAtomsCount == 0, msg.get());
+  }
+
+  // During the course of this function, the atom table is locked. This means
+  // that, barring refcounting bugs in consumers, an atom can never go from
+  // refcount == 0 to refcount != 0 during a GC. However, an atom _can_ go from
+  // refcount != 0 to refcount == 0 if a Release() occurs in parallel with GC.
+  // This means that we cannot assert that gUnusedAtomCount == removedCount, and
+  // thus that there are no unused atoms at the end of a GC. We can and do,
+  // however, assert this after the last GC at shutdown.
+  if (aKind == GCKind::RegularOperation) {
+    MOZ_ASSERT(removedCount <= gUnusedAtomCount);
+  } else {
+    // Complain if somebody adds new GCKind enums.
+    MOZ_ASSERT(aKind == GCKind::Shutdown);
+    // Our unused atom count should be accurate.
+    MOZ_ASSERT(removedCount == gUnusedAtomCount);
+  }
+
+  gUnusedAtomCount -= removedCount;
+}
+
+NS_IMPL_QUERY_INTERFACE(DynamicAtom, nsIAtom)
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+DynamicAtom::AddRef(void)
+{
+  nsrefcnt count = ++mRefCnt;
+  if (count == 1) {
+    MOZ_ASSERT(gUnusedAtomCount > 0);
+    gUnusedAtomCount--;
+  }
+  return count;
+}
+
+#ifdef DEBUG
+// We set a lower GC threshold for atoms in debug builds so that we exercise
+// the GC machinery more often.
+static const uint32_t kAtomGCThreshold = 20;
+#else
+static const uint32_t kAtomGCThreshold = 10000;
+#endif
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+DynamicAtom::Release(void)
+{
+  MOZ_ASSERT(mRefCnt > 0);
+  nsrefcnt count = --mRefCnt;
+  if (count == 0) {
+    if (++gUnusedAtomCount >= kAtomGCThreshold) {
+      GCAtomTable();
+    }
+  }
+
+  return count;
+}
+
+DynamicAtom::~DynamicAtom()
+{
+  nsStringBuffer::FromData(mString)->Release();
+}
+
+//----------------------------------------------------------------------
+
+class StaticAtomEntry : public PLDHashEntryHdr
+{
+public:
+  typedef const nsAString& KeyType;
+  typedef const nsAString* KeyTypePointer;
+
+  explicit StaticAtomEntry(KeyTypePointer aKey) {}
+  StaticAtomEntry(const StaticAtomEntry& aOther) : mAtom(aOther.mAtom) {}
+
+  // We do not delete the atom because that's done when gAtomTable is
+  // destroyed -- which happens immediately after gStaticAtomTable is destroyed
+  // -- in NS_PurgeAtomTable().
+  ~StaticAtomEntry() {}
+
+  bool KeyEquals(KeyTypePointer aKey) const
+  {
+    return mAtom->Equals(*aKey);
+  }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return HashString(*aKey);
+  }
+
+  enum { ALLOW_MEMMOVE = true };
+
+  // StaticAtoms aren't really refcounted. Because these entries live in a
+  // global hashtable, this reference is essentially owning.
+  StaticAtom* MOZ_OWNING_REF mAtom;
+};
+
+/**
+ * A hashtable of static atoms that existed at app startup. This hashtable
+ * helps nsHtml5AtomTable.
+ */
+typedef nsTHashtable<StaticAtomEntry> StaticAtomTable;
+static StaticAtomTable* gStaticAtomTable = nullptr;
+
+/**
+ * Whether it is still OK to add atoms to gStaticAtomTable.
+ */
+static bool gStaticAtomTableSealed = false;
+
+// The atom table very quickly gets 10,000+ entries in it (or even 100,000+).
+// But choosing the best initial length has some subtleties: we add ~2700
+// static atoms to the table at start-up, and then we start adding and removing
+// dynamic atoms. If we make the table too big to start with, when the first
+// dynamic atom gets removed the load factor will be < 25% and so we will
+// shrink it to 4096 entries.
+//
+// By choosing an initial length of 4096, we get an initial capacity of 8192.
+// That's the biggest initial capacity that will let us be > 25% full when the
+// first dynamic atom is removed (when the count is ~2700), thus avoiding any
+// shrinking.
+#define ATOM_HASHTABLE_INITIAL_LENGTH  4096
+
+void
+NS_InitAtomTable()
+{
+  MOZ_ASSERT(!gAtomTable);
+  gAtomTable = new PLDHashTable(&AtomTableOps, sizeof(AtomTableEntry),
+                                ATOM_HASHTABLE_INITIAL_LENGTH);
+  gAtomTableLock = new Mutex("Atom Table Lock");
+}
+
+void
+NS_ShutdownAtomTable()
+{
+  delete gStaticAtomTable;
+  gStaticAtomTable = nullptr;
+
+#ifdef NS_FREE_PERMANENT_DATA
+  // Do a final GC to satisfy leak checking. We skip this step in release
+  // builds.
+  {
+    MutexAutoLock lock(*gAtomTableLock);
+    DynamicAtom::GCAtomTableLocked(lock, DynamicAtom::GCKind::Shutdown);
+  }
+#endif
+
+  delete gAtomTable;
+  gAtomTable = nullptr;
+  delete gAtomTableLock;
+  gAtomTableLock = nullptr;
+}
+
+void
+NS_SizeOfAtomTablesIncludingThis(MallocSizeOf aMallocSizeOf,
+                                 size_t* aMain, size_t* aStatic)
+{
+  MutexAutoLock lock(*gAtomTableLock);
+  *aMain = gAtomTable->ShallowSizeOfIncludingThis(aMallocSizeOf);
+  for (auto iter = gAtomTable->Iter(); !iter.Done(); iter.Next()) {
+    auto entry = static_cast<AtomTableEntry*>(iter.Get());
+    *aMain += entry->mAtom->SizeOfIncludingThis(aMallocSizeOf);
+  }
+
+  // The atoms pointed to by gStaticAtomTable are also pointed to by gAtomTable,
+  // and they're measured by the loop above. So no need to measure them here.
+  *aStatic = gStaticAtomTable
+           ? gStaticAtomTable->ShallowSizeOfIncludingThis(aMallocSizeOf)
+           : 0;
+}
+
+static inline AtomTableEntry*
+GetAtomHashEntry(const char* aString, uint32_t aLength, uint32_t* aHashOut)
+{
+  gAtomTableLock->AssertCurrentThreadOwns();
+  AtomTableKey key(aString, aLength, aHashOut);
+  // This is an infallible add.
+  return static_cast<AtomTableEntry*>(gAtomTable->Add(&key));
+}
+
+static inline AtomTableEntry*
+GetAtomHashEntry(const char16_t* aString, uint32_t aLength, uint32_t* aHashOut)
+{
+  gAtomTableLock->AssertCurrentThreadOwns();
+  AtomTableKey key(aString, aLength, aHashOut);
+  // This is an infallible add.
+  return static_cast<AtomTableEntry*>(gAtomTable->Add(&key));
+}
+
+void
+RegisterStaticAtoms(const nsStaticAtom* aAtoms, uint32_t aAtomCount)
+{
+  MutexAutoLock lock(*gAtomTableLock);
+
+  MOZ_RELEASE_ASSERT(!gStaticAtomTableSealed,
+                     "Atom table has already been sealed!");
+
+  if (!gStaticAtomTable) {
+    gStaticAtomTable = new StaticAtomTable();
+  }
+
+  for (uint32_t i = 0; i < aAtomCount; ++i) {
+    nsStringBuffer* stringBuffer = aAtoms[i].mStringBuffer;
+    nsIAtom** atomp = aAtoms[i].mAtom;
+
+    MOZ_ASSERT(nsCRT::IsAscii(static_cast<char16_t*>(stringBuffer->Data())));
+
+    uint32_t stringLen = stringBuffer->StorageSize() / sizeof(char16_t) - 1;
+
+    uint32_t hash;
+    AtomTableEntry* he =
+      GetAtomHashEntry(static_cast<char16_t*>(stringBuffer->Data()),
+                       stringLen, &hash);
+
+    nsIAtom* atom = he->mAtom;
+    if (atom) {
+      // Disallow creating a dynamic atom, and then later, while the
+      // dynamic atom is still alive, registering that same atom as a
+      // static atom.  It causes subtle bugs, and we're programming in
+      // C++ here, not Smalltalk.
+      if (!atom->IsStaticAtom()) {
+        nsAutoCString name;
+        atom->ToUTF8String(name);
+        MOZ_CRASH_UNSAFE_PRINTF(
+          "Static atom registration for %s should be pushed back", name.get());
+      }
+    } else {
+      atom = new StaticAtom(stringBuffer, stringLen, hash);
+      he->mAtom = atom;
+    }
+    *atomp = atom;
+
+    if (!gStaticAtomTableSealed) {
+      StaticAtomEntry* entry =
+        gStaticAtomTable->PutEntry(nsDependentAtomString(atom));
+      MOZ_ASSERT(atom->IsStaticAtom());
+      entry->mAtom = static_cast<StaticAtom*>(atom);
+    }
+  }
+}
+
+already_AddRefed<nsIAtom>
+NS_Atomize(const char* aUTF8String)
+{
+  return NS_Atomize(nsDependentCString(aUTF8String));
+}
+
+already_AddRefed<nsIAtom>
+NS_Atomize(const nsACString& aUTF8String)
+{
+  MutexAutoLock lock(*gAtomTableLock);
+  uint32_t hash;
+  AtomTableEntry* he = GetAtomHashEntry(aUTF8String.Data(),
+                                        aUTF8String.Length(),
+                                        &hash);
+
+  if (he->mAtom) {
+    nsCOMPtr<nsIAtom> atom = he->mAtom;
+
+    return atom.forget();
+  }
+
+  // This results in an extra addref/release of the nsStringBuffer.
+  // Unfortunately there doesn't seem to be any APIs to avoid that.
+  // Actually, now there is, sort of: ForgetSharedBuffer.
+  nsString str;
+  CopyUTF8toUTF16(aUTF8String, str);
+  RefPtr<DynamicAtom> atom = DynamicAtom::Create(str, hash);
+
+  he->mAtom = atom;
+
+  return atom.forget();
+}
+
+already_AddRefed<nsIAtom>
+NS_Atomize(const char16_t* aUTF16String)
+{
+  return NS_Atomize(nsDependentString(aUTF16String));
+}
+
+already_AddRefed<nsIAtom>
+NS_Atomize(const nsAString& aUTF16String)
+{
+  MutexAutoLock lock(*gAtomTableLock);
+  uint32_t hash;
+  AtomTableEntry* he = GetAtomHashEntry(aUTF16String.Data(),
+                                        aUTF16String.Length(),
+                                        &hash);
+
+  if (he->mAtom) {
+    nsCOMPtr<nsIAtom> atom = he->mAtom;
+
+    return atom.forget();
+  }
+
+  RefPtr<DynamicAtom> atom = DynamicAtom::Create(aUTF16String, hash);
+  he->mAtom = atom;
+
+  return atom.forget();
+}
+
+nsrefcnt
+NS_GetNumberOfAtoms(void)
+{
+  DynamicAtom::GCAtomTable(); // Trigger a GC so that we return a deterministic result.
+  MutexAutoLock lock(*gAtomTableLock);
+  return gAtomTable->EntryCount();
+}
+
+nsIAtom*
+NS_GetStaticAtom(const nsAString& aUTF16String)
+{
+  NS_PRECONDITION(gStaticAtomTable, "Static atom table not created yet.");
+  NS_PRECONDITION(gStaticAtomTableSealed, "Static atom table not sealed yet.");
+  StaticAtomEntry* entry = gStaticAtomTable->GetEntry(aUTF16String);
+  return entry ? entry->mAtom : nullptr;
+}
+
+void
+NS_SealStaticAtomTable()
+{
+  gStaticAtomTableSealed = true;
+}
diff --git a/xpcom/ds/nsAtomTable.h b/xpcom/ds/nsAtomTable.h
new file mode 100644
index 000000000..89e5792f7
--- /dev/null
+++ b/xpcom/ds/nsAtomTable.h
@@ -0,0 +1,19 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsAtomTable_h__
+#define nsAtomTable_h__
+
+#include "mozilla/MemoryReporting.h"
+#include <stddef.h>
+
+void NS_InitAtomTable();
+void NS_ShutdownAtomTable();
+
+void NS_SizeOfAtomTablesIncludingThis(mozilla::MallocSizeOf aMallocSizeOf,
+                                      size_t* aMain, size_t* aStatic);
+
+#endif // nsAtomTable_h__
diff --git a/xpcom/ds/nsCRT.cpp b/xpcom/ds/nsCRT.cpp
new file mode 100644
index 000000000..0d11a8c26
--- /dev/null
+++ b/xpcom/ds/nsCRT.cpp
@@ -0,0 +1,187 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+/**
+ * MODULE NOTES:
+ * @update  gess7/30/98
+ *
+ * Much as I hate to do it, we were using string compares wrong.
+ * Often, programmers call functions like strcmp(s1,s2), and pass
+ * one or more null strings. Rather than blow up on these, I've
+ * added quick checks to ensure that cases like this don't cause
+ * us to fail.
+ *
+ * In general, if you pass a null into any of these string compare
+ * routines, we simply return 0.
+ */
+
+
+#include "nsCRT.h"
+#include "nsDebug.h"
+
+//----------------------------------------------------------------------
+
+
+////////////////////////////////////////////////////////////////////////////////
+// My lovely strtok routine
+
+#define IS_DELIM(m, c)          ((m)[(c) >> 3] & (1 << ((c) & 7)))
+#define SET_DELIM(m, c)         ((m)[(c) >> 3] |= (1 << ((c) & 7)))
+#define DELIM_TABLE_SIZE        32
+
+char*
+nsCRT::strtok(char* aString, const char* aDelims, char** aNewStr)
+{
+  NS_ASSERTION(aString,
+               "Unlike regular strtok, the first argument cannot be null.");
+
+  char delimTable[DELIM_TABLE_SIZE];
+  uint32_t i;
+  char* result;
+  char* str = aString;
+
+  for (i = 0; i < DELIM_TABLE_SIZE; ++i) {
+    delimTable[i] = '\0';
+  }
+
+  for (i = 0; aDelims[i]; i++) {
+    SET_DELIM(delimTable, static_cast<uint8_t>(aDelims[i]));
+  }
+  NS_ASSERTION(aDelims[i] == '\0', "too many delimiters");
+
+  // skip to beginning
+  while (*str && IS_DELIM(delimTable, static_cast<uint8_t>(*str))) {
+    str++;
+  }
+  result = str;
+
+  // fix up the end of the token
+  while (*str) {
+    if (IS_DELIM(delimTable, static_cast<uint8_t>(*str))) {
+      *str++ = '\0';
+      break;
+    }
+    str++;
+  }
+  *aNewStr = str;
+
+  return str == result ? nullptr : result;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+/**
+ * Compare unichar string ptrs, stopping at the 1st null
+ * NOTE: If both are null, we return 0.
+ * NOTE: We terminate the search upon encountering a nullptr
+ *
+ * @update  gess 11/10/99
+ * @param   s1 and s2 both point to unichar strings
+ * @return  0 if they match, -1 if s1<s2; 1 if s1>s2
+ */
+int32_t
+nsCRT::strcmp(const char16_t* aStr1, const char16_t* aStr2)
+{
+  if (aStr1 && aStr2) {
+    for (;;) {
+      char16_t c1 = *aStr1++;
+      char16_t c2 = *aStr2++;
+      if (c1 != c2) {
+        if (c1 < c2) {
+          return -1;
+        }
+        return 1;
+      }
+      if (c1 == 0 || c2 == 0) {
+        break;
+      }
+    }
+  } else {
+    if (aStr1) {  // aStr2 must have been null
+      return -1;
+    }
+    if (aStr2) {  // aStr1 must have been null
+      return 1;
+    }
+  }
+  return 0;
+}
+
+/**
+ * Compare unichar string ptrs, stopping at the 1st null or nth char.
+ * NOTE: If either is null, we return 0.
+ * NOTE: We DO NOT terminate the search upon encountering nullptr's before N
+ *
+ * @update  gess 11/10/99
+ * @param   s1 and s2 both point to unichar strings
+ * @return  0 if they match, -1 if s1<s2; 1 if s1>s2
+ */
+int32_t
+nsCRT::strncmp(const char16_t* aStr1, const char16_t* aStr2, uint32_t aNum)
+{
+  if (aStr1 && aStr2) {
+    if (aNum != 0) {
+      do {
+        char16_t c1 = *aStr1++;
+        char16_t c2 = *aStr2++;
+        if (c1 != c2) {
+          if (c1 < c2) {
+            return -1;
+          }
+          return 1;
+        }
+      } while (--aNum != 0);
+    }
+  }
+  return 0;
+}
+
+const char*
+nsCRT::memmem(const char* aHaystack, uint32_t aHaystackLen,
+              const char* aNeedle, uint32_t aNeedleLen)
+{
+  // Sanity checking
+  if (!(aHaystack && aNeedle && aHaystackLen && aNeedleLen &&
+        aNeedleLen <= aHaystackLen)) {
+    return nullptr;
+  }
+
+#ifdef HAVE_MEMMEM
+  return (const char*)::memmem(aHaystack, aHaystackLen, aNeedle, aNeedleLen);
+#else
+  // No memmem means we need to roll our own.  This isn't really optimized
+  // for performance ... if that becomes an issue we can take some inspiration
+  // from the js string compare code in jsstr.cpp
+  for (uint32_t i = 0; i < aHaystackLen - aNeedleLen; i++) {
+    if (!memcmp(aHaystack + i, aNeedle, aNeedleLen)) {
+      return aHaystack + i;
+    }
+  }
+#endif
+  return nullptr;
+}
+
+// This should use NSPR but NSPR isn't exporting its PR_strtoll function
+// Until then...
+int64_t
+nsCRT::atoll(const char* aStr)
+{
+  if (!aStr) {
+    return 0;
+  }
+
+  int64_t ll = 0;
+
+  while (*aStr && *aStr >= '0' && *aStr <= '9') {
+    ll *= 10;
+    ll += *aStr - '0';
+    aStr++;
+  }
+
+  return ll;
+}
+
diff --git a/xpcom/ds/nsCRT.h b/xpcom/ds/nsCRT.h
new file mode 100644
index 000000000..6fad83d6d
--- /dev/null
+++ b/xpcom/ds/nsCRT.h
@@ -0,0 +1,186 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef nsCRT_h___
+#define nsCRT_h___
+
+#include <stdlib.h>
+#include <ctype.h>
+#include "plstr.h"
+#include "nscore.h"
+#include "nsCRTGlue.h"
+
+#if defined(XP_WIN)
+#  define NS_LINEBREAK           "\015\012"
+#  define NS_LINEBREAK_LEN       2
+#else
+#  ifdef XP_UNIX
+#    define NS_LINEBREAK         "\012"
+#    define NS_LINEBREAK_LEN     1
+#  endif /* XP_UNIX */
+#endif /* XP_WIN */
+
+extern const char16_t kIsoLatin1ToUCS2[256];
+
+// This macro can be used in a class declaration for classes that want
+// to ensure that their instance memory is zeroed.
+#define NS_DECL_AND_IMPL_ZEROING_OPERATOR_NEW   \
+  void* operator new(size_t sz) CPP_THROW_NEW { \
+    void* rv = ::operator new(sz);              \
+    if (rv) {                                   \
+      memset(rv, 0, sz);                        \
+    }                                           \
+    return rv;                                  \
+  }                                             \
+  void operator delete(void* ptr) {             \
+    ::operator delete(ptr);                     \
+  }
+
+// This macro works with the next macro to declare a non-inlined
+// version of the above.
+#define NS_DECL_ZEROING_OPERATOR_NEW           \
+  void* operator new(size_t sz) CPP_THROW_NEW; \
+  void operator delete(void* ptr);
+
+#define NS_IMPL_ZEROING_OPERATOR_NEW(_class)            \
+  void* _class::operator new(size_t sz) CPP_THROW_NEW { \
+    void* rv = ::operator new(sz);                      \
+    if (rv) {                                           \
+      memset(rv, 0, sz);                                \
+    }                                                   \
+    return rv;                                          \
+  }                                                     \
+  void _class::operator delete(void* ptr) {             \
+    ::operator delete(ptr);                             \
+  }
+
+// Freeing helper
+#define CRTFREEIF(x) if (x) { nsCRT::free(x); x = 0; }
+
+/// This is a wrapper class around all the C runtime functions.
+
+class nsCRT
+{
+public:
+  enum
+  {
+    LF = '\n'   /* Line Feed */,
+    VTAB = '\v' /* Vertical Tab */,
+    CR = '\r'   /* Carriage Return */
+  };
+
+  /// String comparison.
+  static int32_t strcmp(const char* aStr1, const char* aStr2)
+  {
+    return int32_t(PL_strcmp(aStr1, aStr2));
+  }
+
+  static int32_t strncmp(const char* aStr1, const char* aStr2,
+                         uint32_t aMaxLen)
+  {
+    return int32_t(PL_strncmp(aStr1, aStr2, aMaxLen));
+  }
+
+  /// Case-insensitive string comparison.
+  static int32_t strcasecmp(const char* aStr1, const char* aStr2)
+  {
+    return int32_t(PL_strcasecmp(aStr1, aStr2));
+  }
+
+  /// Case-insensitive string comparison with length
+  static int32_t strncasecmp(const char* aStr1, const char* aStr2,
+                             uint32_t aMaxLen)
+  {
+    int32_t result = int32_t(PL_strncasecmp(aStr1, aStr2, aMaxLen));
+    //Egads. PL_strncasecmp is returning *very* negative numbers.
+    //Some folks expect -1,0,1, so let's temper its enthusiasm.
+    if (result < 0) {
+      result = -1;
+    }
+    return result;
+  }
+
+  static int32_t strncmp(const char* aStr1, const char* aStr2, int32_t aMaxLen)
+  {
+    // inline the first test (assumes strings are not null):
+    int32_t diff =
+      ((const unsigned char*)aStr1)[0] - ((const unsigned char*)aStr2)[0];
+    if (diff != 0) {
+      return diff;
+    }
+    return int32_t(PL_strncmp(aStr1, aStr2, unsigned(aMaxLen)));
+  }
+
+  /**
+
+    How to use this fancy (thread-safe) version of strtok:
+
+    void main(void) {
+      printf("%s\n\nTokens:\n", string);
+      // Establish string and get the first token:
+      char* newStr;
+      token = nsCRT::strtok(string, seps, &newStr);
+      while (token != nullptr) {
+        // While there are tokens in "string"
+        printf(" %s\n", token);
+        // Get next token:
+        token = nsCRT::strtok(newStr, seps, &newStr);
+      }
+    }
+    * WARNING - STRTOK WHACKS str THE FIRST TIME IT IS CALLED *
+    * MAKE A COPY OF str IF YOU NEED TO USE IT AFTER strtok() *
+  */
+  static char* strtok(char* aStr, const char* aDelims, char** aNewStr);
+
+  /// Like strcmp except for ucs2 strings
+  static int32_t strcmp(const char16_t* aStr1, const char16_t* aStr2);
+  /// Like strcmp except for ucs2 strings
+  static int32_t strncmp(const char16_t* aStr1, const char16_t* aStr2,
+                         uint32_t aMaxLen);
+
+  // The GNU libc has memmem, which is strstr except for binary data
+  // This is our own implementation that uses memmem on platforms
+  // where it's available.
+  static const char* memmem(const char* aHaystack, uint32_t aHaystackLen,
+                            const char* aNeedle, uint32_t aNeedleLen);
+
+  // String to longlong
+  static int64_t atoll(const char* aStr);
+
+  static char ToUpper(char aChar) { return NS_ToUpper(aChar); }
+  static char ToLower(char aChar) { return NS_ToLower(aChar); }
+
+  static bool IsUpper(char aChar) { return NS_IsUpper(aChar); }
+  static bool IsLower(char aChar) { return NS_IsLower(aChar); }
+
+  static bool IsAscii(char16_t aChar) { return NS_IsAscii(aChar); }
+  static bool IsAscii(const char16_t* aString) { return NS_IsAscii(aString); }
+  static bool IsAsciiAlpha(char16_t aChar) { return NS_IsAsciiAlpha(aChar); }
+  static bool IsAsciiDigit(char16_t aChar) { return NS_IsAsciiDigit(aChar); }
+  static bool IsAsciiSpace(char16_t aChar) { return NS_IsAsciiWhitespace(aChar); }
+  static bool IsAscii(const char* aString) { return NS_IsAscii(aString); }
+  static bool IsAscii(const char* aString, uint32_t aLength)
+  {
+    return NS_IsAscii(aString, aLength);
+  }
+};
+
+
+inline bool
+NS_IS_SPACE(char16_t aChar)
+{
+  return ((int(aChar) & 0x7f) == int(aChar)) && isspace(int(aChar));
+}
+
+#define NS_IS_CNTRL(i)   ((((unsigned int) (i)) > 0x7f) ? (int) 0 : iscntrl(i))
+#define NS_IS_DIGIT(i)   ((((unsigned int) (i)) > 0x7f) ? (int) 0 : isdigit(i))
+#if defined(XP_WIN)
+#define NS_IS_ALPHA(VAL) (isascii((int)(VAL)) && isalpha((int)(VAL)))
+#else
+#define NS_IS_ALPHA(VAL) ((((unsigned int) (VAL)) > 0x7f) ? (int) 0 : isalpha((int)(VAL)))
+#endif
+
+
+#endif /* nsCRT_h___ */
diff --git a/xpcom/ds/nsCharSeparatedTokenizer.h b/xpcom/ds/nsCharSeparatedTokenizer.h
new file mode 100644
index 000000000..0e24d9d3e
--- /dev/null
+++ b/xpcom/ds/nsCharSeparatedTokenizer.h
@@ -0,0 +1,200 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __nsCharSeparatedTokenizer_h
+#define __nsCharSeparatedTokenizer_h
+
+#include "mozilla/RangedPtr.h"
+
+#include "nsDependentSubstring.h"
+#include "nsCRT.h"
+
+/**
+ * This parses a SeparatorChar-separated string into tokens.
+ * Whitespace surrounding tokens is not treated as part of tokens, however
+ * whitespace inside a token is. If the final token is the empty string, it is
+ * not returned.
+ *
+ * Some examples, with SeparatorChar = ',':
+ *
+ * "foo, bar, baz" ->      "foo" "bar" "baz"
+ * "foo,bar,baz" ->        "foo" "bar" "baz"
+ * "foo , bar hi , baz" -> "foo" "bar hi" "baz"
+ * "foo, ,bar,baz" ->      "foo" "" "bar" "baz"
+ * "foo,,bar,baz" ->       "foo" "" "bar" "baz"
+ * "foo,bar,baz," ->       "foo" "bar" "baz"
+ *
+ * The function used for whitespace detection is a template argument.
+ * By default, it is NS_IsAsciiWhitespace.
+ */
+template<typename DependentSubstringType, bool IsWhitespace(char16_t)>
+class nsTCharSeparatedTokenizer
+{
+  typedef typename DependentSubstringType::char_type CharType;
+  typedef typename DependentSubstringType::substring_type SubstringType;
+
+public:
+  // Flags -- only one for now. If we need more, they should be defined to
+  // be 1 << 1, 1 << 2, etc. (They're masks, and aFlags is a bitfield.)
+  enum
+  {
+    SEPARATOR_OPTIONAL = 1
+  };
+
+  nsTCharSeparatedTokenizer(const SubstringType& aSource,
+                            CharType aSeparatorChar,
+                            uint32_t aFlags = 0)
+    : mIter(aSource.Data(), aSource.Length())
+    , mEnd(aSource.Data() + aSource.Length(), aSource.Data(),
+           aSource.Length())
+    , mSeparatorChar(aSeparatorChar)
+    , mWhitespaceBeforeFirstToken(false)
+    , mWhitespaceAfterCurrentToken(false)
+    , mSeparatorAfterCurrentToken(false)
+    , mSeparatorOptional(aFlags & SEPARATOR_OPTIONAL)
+  {
+    // Skip initial whitespace
+    while (mIter < mEnd && IsWhitespace(*mIter)) {
+      mWhitespaceBeforeFirstToken = true;
+      ++mIter;
+    }
+  }
+
+  /**
+   * Checks if any more tokens are available.
+   */
+  bool hasMoreTokens() const
+  {
+    MOZ_ASSERT(mIter == mEnd || !IsWhitespace(*mIter),
+               "Should be at beginning of token if there is one");
+
+    return mIter < mEnd;
+  }
+
+  /*
+   * Returns true if there is whitespace prior to the first token.
+   */
+  bool whitespaceBeforeFirstToken() const
+  {
+    return mWhitespaceBeforeFirstToken;
+  }
+
+  /*
+   * Returns true if there is a separator after the current token.
+   * Useful if you want to check whether the last token has a separator
+   * after it which may not be valid.
+   */
+  bool separatorAfterCurrentToken() const
+  {
+    return mSeparatorAfterCurrentToken;
+  }
+
+  /*
+   * Returns true if there is any whitespace after the current token.
+   */
+  bool whitespaceAfterCurrentToken() const
+  {
+    return mWhitespaceAfterCurrentToken;
+  }
+
+  /**
+   * Returns the next token.
+   */
+  const DependentSubstringType nextToken()
+  {
+    mozilla::RangedPtr<const CharType> tokenStart = mIter;
+    mozilla::RangedPtr<const CharType> tokenEnd = mIter;
+
+    MOZ_ASSERT(mIter == mEnd || !IsWhitespace(*mIter),
+               "Should be at beginning of token if there is one");
+
+    // Search until we hit separator or end (or whitespace, if a separator
+    // isn't required -- see clause with 'break' below).
+    while (mIter < mEnd && *mIter != mSeparatorChar) {
+      // Skip to end of the current word.
+      while (mIter < mEnd &&
+             !IsWhitespace(*mIter) && *mIter != mSeparatorChar) {
+        ++mIter;
+      }
+      tokenEnd = mIter;
+
+      // Skip whitespace after the current word.
+      mWhitespaceAfterCurrentToken = false;
+      while (mIter < mEnd && IsWhitespace(*mIter)) {
+        mWhitespaceAfterCurrentToken = true;
+        ++mIter;
+      }
+      if (mSeparatorOptional) {
+        // We've hit (and skipped) whitespace, and that's sufficient to end
+        // our token, regardless of whether we've reached a SeparatorChar.
+        break;
+      } // (else, we'll keep looping until we hit mEnd or SeparatorChar)
+    }
+
+    mSeparatorAfterCurrentToken = (mIter != mEnd &&
+                                   *mIter == mSeparatorChar);
+    MOZ_ASSERT(mSeparatorOptional ||
+               (mSeparatorAfterCurrentToken == (mIter < mEnd)),
+               "If we require a separator and haven't hit the end of "
+               "our string, then we shouldn't have left the loop "
+               "unless we hit a separator");
+
+    // Skip separator (and any whitespace after it), if we're at one.
+    if (mSeparatorAfterCurrentToken) {
+      ++mIter;
+
+      while (mIter < mEnd && IsWhitespace(*mIter)) {
+        mWhitespaceAfterCurrentToken = true;
+        ++mIter;
+      }
+    }
+
+    return Substring(tokenStart.get(), tokenEnd.get());
+  }
+
+private:
+  mozilla::RangedPtr<const CharType> mIter;
+  const mozilla::RangedPtr<const CharType> mEnd;
+  CharType mSeparatorChar;
+  bool mWhitespaceBeforeFirstToken;
+  bool mWhitespaceAfterCurrentToken;
+  bool mSeparatorAfterCurrentToken;
+  bool mSeparatorOptional;
+};
+
+template<bool IsWhitespace(char16_t) = NS_IsAsciiWhitespace>
+class nsCharSeparatedTokenizerTemplate
+  : public nsTCharSeparatedTokenizer<nsDependentSubstring, IsWhitespace>
+{
+public:
+  nsCharSeparatedTokenizerTemplate(const nsSubstring& aSource,
+                                   char16_t aSeparatorChar,
+                                   uint32_t aFlags = 0)
+    : nsTCharSeparatedTokenizer<nsDependentSubstring,
+                                IsWhitespace>(aSource, aSeparatorChar, aFlags)
+  {
+  }
+};
+
+typedef nsCharSeparatedTokenizerTemplate<> nsCharSeparatedTokenizer;
+
+template<bool IsWhitespace(char16_t) = NS_IsAsciiWhitespace>
+class nsCCharSeparatedTokenizerTemplate
+  : public nsTCharSeparatedTokenizer<nsDependentCSubstring, IsWhitespace>
+{
+public:
+  nsCCharSeparatedTokenizerTemplate(const nsCSubstring& aSource,
+                                    char aSeparatorChar,
+                                    uint32_t aFlags = 0)
+    : nsTCharSeparatedTokenizer<nsDependentCSubstring,
+                                IsWhitespace>(aSource, aSeparatorChar, aFlags)
+  {
+  }
+};
+
+typedef nsCCharSeparatedTokenizerTemplate<> nsCCharSeparatedTokenizer;
+
+#endif /* __nsCharSeparatedTokenizer_h */
diff --git a/xpcom/ds/nsCheapSets.h b/xpcom/ds/nsCheapSets.h
new file mode 100644
index 000000000..d75e60d20
--- /dev/null
+++ b/xpcom/ds/nsCheapSets.h
@@ -0,0 +1,171 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __nsCheapSets_h__
+#define __nsCheapSets_h__
+
+#include "nsTHashtable.h"
+#include <stdint.h>
+
+enum nsCheapSetOperator
+{
+  OpNext = 0,   // enumerator says continue
+  OpRemove = 1, // enumerator says remove and continue
+};
+
+/**
+ * A set that takes up minimal size when there are 0 or 1 entries in the set.
+ * Use for cases where sizes of 0 and 1 are even slightly common.
+ */
+template<typename EntryType>
+class nsCheapSet
+{
+public:
+  typedef typename EntryType::KeyType KeyType;
+  typedef nsCheapSetOperator (*Enumerator)(EntryType* aEntry, void* userArg);
+
+  nsCheapSet() : mState(ZERO) {}
+  ~nsCheapSet() { Clear(); }
+
+  /**
+   * Remove all entries.
+   */
+  void Clear()
+  {
+    switch (mState) {
+      case ZERO:
+        break;
+      case ONE:
+        GetSingleEntry()->~EntryType();
+        break;
+      case MANY:
+        delete mUnion.table;
+        break;
+      default:
+        NS_NOTREACHED("bogus state");
+        break;
+    }
+    mState = ZERO;
+  }
+
+  void Put(const KeyType aVal);
+
+  void Remove(const KeyType aVal);
+
+  bool Contains(const KeyType aVal)
+  {
+    switch (mState) {
+      case ZERO:
+        return false;
+      case ONE:
+        return GetSingleEntry()->KeyEquals(EntryType::KeyToPointer(aVal));
+      case MANY:
+        return !!mUnion.table->GetEntry(aVal);
+      default:
+        NS_NOTREACHED("bogus state");
+        return false;
+    }
+  }
+
+  uint32_t EnumerateEntries(Enumerator aEnumFunc, void* aUserArg)
+  {
+    switch (mState) {
+      case ZERO:
+        return 0;
+      case ONE:
+        if (aEnumFunc(GetSingleEntry(), aUserArg) == OpRemove) {
+          GetSingleEntry()->~EntryType();
+          mState = ZERO;
+        }
+        return 1;
+      case MANY: {
+        uint32_t n = mUnion.table->Count();
+        for (auto iter = mUnion.table->Iter(); !iter.Done(); iter.Next()) {
+          auto entry = static_cast<EntryType*>(iter.Get());
+          if (aEnumFunc(entry, aUserArg) == OpRemove) {
+            iter.Remove();
+          }
+        }
+        return n;
+      }
+      default:
+        NS_NOTREACHED("bogus state");
+        return 0;
+    }
+  }
+
+private:
+  EntryType* GetSingleEntry()
+  {
+    return reinterpret_cast<EntryType*>(&mUnion.singleEntry[0]);
+  }
+
+  enum SetState
+  {
+    ZERO,
+    ONE,
+    MANY
+  };
+
+  union
+  {
+    nsTHashtable<EntryType>* table;
+    char singleEntry[sizeof(EntryType)];
+  } mUnion;
+  enum SetState mState;
+};
+
+template<typename EntryType>
+void
+nsCheapSet<EntryType>::Put(const KeyType aVal)
+{
+  switch (mState) {
+    case ZERO:
+      new (GetSingleEntry()) EntryType(EntryType::KeyToPointer(aVal));
+      mState = ONE;
+      return;
+    case ONE: {
+      nsTHashtable<EntryType>* table = new nsTHashtable<EntryType>();
+      EntryType* entry = GetSingleEntry();
+      table->PutEntry(entry->GetKey());
+      entry->~EntryType();
+      mUnion.table = table;
+      mState = MANY;
+    }
+    MOZ_FALLTHROUGH;
+
+    case MANY:
+      mUnion.table->PutEntry(aVal);
+      return;
+    default:
+      NS_NOTREACHED("bogus state");
+      return;
+  }
+}
+
+template<typename EntryType>
+void
+nsCheapSet<EntryType>::Remove(const KeyType aVal)
+{
+  switch (mState) {
+    case ZERO:
+      break;
+    case ONE:
+      if (Contains(aVal)) {
+        GetSingleEntry()->~EntryType();
+        mState = ZERO;
+      }
+      break;
+    case MANY:
+      mUnion.table->RemoveEntry(aVal);
+      break;
+    default:
+      NS_NOTREACHED("bogus state");
+      break;
+  }
+}
+
+#endif
diff --git a/xpcom/ds/nsExpirationTracker.h b/xpcom/ds/nsExpirationTracker.h
new file mode 100644
index 000000000..2e77895db
--- /dev/null
+++ b/xpcom/ds/nsExpirationTracker.h
@@ -0,0 +1,570 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef NSEXPIRATIONTRACKER_H_
+#define NSEXPIRATIONTRACKER_H_
+
+#include "mozilla/Logging.h"
+#include "nsTArray.h"
+#include "nsITimer.h"
+#include "nsCOMPtr.h"
+#include "nsAutoPtr.h"
+#include "nsComponentManagerUtils.h"
+#include "nsIEventTarget.h"
+#include "nsIObserver.h"
+#include "nsIObserverService.h"
+#include "nsThreadUtils.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Services.h"
+
+/**
+ * Data used to track the expiration state of an object. We promise that this
+ * is 32 bits so that objects that includes this as a field can pad and align
+ * efficiently.
+ */
+struct nsExpirationState
+{
+  enum
+  {
+    NOT_TRACKED = (1U << 4) - 1,
+    MAX_INDEX_IN_GENERATION = (1U << 28) - 1
+  };
+
+  nsExpirationState() : mGeneration(NOT_TRACKED) {}
+  bool IsTracked() { return mGeneration != NOT_TRACKED; }
+
+  /**
+   * The generation that this object belongs to, or NOT_TRACKED.
+   */
+  uint32_t mGeneration:4;
+  uint32_t mIndexInGeneration:28;
+};
+
+/**
+ * ExpirationTracker classes:
+ * - ExpirationTrackerImpl (Thread-safe class)
+ * - nsExpirationTracker (Main-thread only class)
+ *
+ * These classes can track the lifetimes and usage of a large number of
+ * objects, and send a notification some window of time after a live object was
+ * last used. This is very useful when you manage a large number of objects
+ * and want to flush some after they haven't been used for a while.
+ * nsExpirationTracker is designed to be very space and time efficient.
+ *
+ * The type parameter T is the object type that we will track pointers to. T
+ * must include an accessible method GetExpirationState() that returns a
+ * pointer to an nsExpirationState associated with the object (preferably,
+ * stored in a field of the object).
+ *
+ * The parameter K is the number of generations that will be used. Increasing
+ * the number of generations narrows the window within which we promise
+ * to fire notifications, at a slight increase in space cost for the tracker.
+ * We require 2 <= K <= nsExpirationState::NOT_TRACKED (currently 15).
+ *
+ * To use this class, you need to inherit from it and override the
+ * NotifyExpired() method.
+ *
+ * The approach is to track objects in K generations. When an object is accessed
+ * it moves from its current generation to the newest generation. Generations
+ * are stored in a cyclic array; when a timer interrupt fires, we advance
+ * the current generation pointer to effectively age all objects very efficiently.
+ * By storing information in each object about its generation and index within its
+ * generation array, we make removal of objects from a generation very cheap.
+ *
+ * Future work:
+ * -- Add a method to change the timer period?
+ */
+
+/**
+ * Base class for ExiprationTracker implementations.
+ *
+ * nsExpirationTracker class below is a specialized class to be inherited by the
+ * instances to be accessed only on main-thread.
+ *
+ * For creating a thread-safe tracker, you can define a subclass inheriting this
+ * base class and specialize the Mutex and AutoLock to be used.
+ *
+ */
+template<typename T, uint32_t K, typename Mutex, typename AutoLock>
+class ExpirationTrackerImpl
+{
+public:
+  /**
+   * Initialize the tracker.
+   * @param aTimerPeriod the timer period in milliseconds. The guarantees
+   * provided by the tracker are defined in terms of this period. If the
+   * period is zero, then we don't use a timer and rely on someone calling
+   * AgeOneGenerationLocked explicitly.
+   */
+  ExpirationTrackerImpl(uint32_t aTimerPeriod, const char* aName)
+    : mTimerPeriod(aTimerPeriod)
+    , mNewestGeneration(0)
+    , mInAgeOneGeneration(false)
+    , mName(aName)
+  {
+    static_assert(K >= 2 && K <= nsExpirationState::NOT_TRACKED,
+                  "Unsupported number of generations (must be 2 <= K <= 15)");
+    MOZ_ASSERT(NS_IsMainThread());
+    mObserver = new ExpirationTrackerObserver();
+    mObserver->Init(this);
+  }
+
+  virtual ~ExpirationTrackerImpl()
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+    if (mTimer) {
+      mTimer->Cancel();
+    }
+    mObserver->Destroy();
+  }
+
+  /**
+   * Add an object to be tracked. It must not already be tracked. It will
+   * be added to the newest generation, i.e., as if it was just used.
+   * @return an error on out-of-memory
+   */
+  nsresult AddObjectLocked(T* aObj, const AutoLock& aAutoLock)
+  {
+    nsExpirationState* state = aObj->GetExpirationState();
+    NS_ASSERTION(!state->IsTracked(),
+                 "Tried to add an object that's already tracked");
+    nsTArray<T*>& generation = mGenerations[mNewestGeneration];
+    uint32_t index = generation.Length();
+    if (index > nsExpirationState::MAX_INDEX_IN_GENERATION) {
+      NS_WARNING("More than 256M elements tracked, this is probably a problem");
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    if (index == 0) {
+      // We might need to start the timer
+      nsresult rv = CheckStartTimerLocked(aAutoLock);
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+    }
+    if (!generation.AppendElement(aObj)) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    state->mGeneration = mNewestGeneration;
+    state->mIndexInGeneration = index;
+    return NS_OK;
+  }
+
+  /**
+   * Remove an object from the tracker. It must currently be tracked.
+   */
+  void RemoveObjectLocked(T* aObj, const AutoLock& aAutoLock)
+  {
+    nsExpirationState* state = aObj->GetExpirationState();
+    NS_ASSERTION(state->IsTracked(), "Tried to remove an object that's not tracked");
+    nsTArray<T*>& generation = mGenerations[state->mGeneration];
+    uint32_t index = state->mIndexInGeneration;
+    NS_ASSERTION(generation.Length() > index &&
+                 generation[index] == aObj, "Object is lying about its index");
+    // Move the last object to fill the hole created by removing aObj
+    uint32_t last = generation.Length() - 1;
+    T* lastObj = generation[last];
+    generation[index] = lastObj;
+    lastObj->GetExpirationState()->mIndexInGeneration = index;
+    generation.RemoveElementAt(last);
+    state->mGeneration = nsExpirationState::NOT_TRACKED;
+    // We do not check whether we need to stop the timer here. The timer
+    // will check that itself next time it fires. Checking here would not
+    // be efficient since we'd need to track all generations. Also we could
+    // thrash by incessantly creating and destroying timers if someone
+    // kept adding and removing an object from the tracker.
+  }
+
+  /**
+   * Notify that an object has been used.
+   * @return an error if we lost the object from the tracker...
+   */
+  nsresult MarkUsedLocked(T* aObj, const AutoLock& aAutoLock)
+  {
+    nsExpirationState* state = aObj->GetExpirationState();
+    if (mNewestGeneration == state->mGeneration) {
+      return NS_OK;
+    }
+    RemoveObjectLocked(aObj, aAutoLock);
+    return AddObjectLocked(aObj, aAutoLock);
+  }
+
+  /**
+   * The timer calls this, but it can also be manually called if you want
+   * to age objects "artifically". This can result in calls to NotifyExpiredLocked.
+   */
+  void AgeOneGenerationLocked(const AutoLock& aAutoLock)
+  {
+    if (mInAgeOneGeneration) {
+      NS_WARNING("Can't reenter AgeOneGeneration from NotifyExpired");
+      return;
+    }
+
+    mInAgeOneGeneration = true;
+    uint32_t reapGeneration =
+      mNewestGeneration > 0 ? mNewestGeneration - 1 : K - 1;
+    nsTArray<T*>& generation = mGenerations[reapGeneration];
+    // The following is rather tricky. We have to cope with objects being
+    // removed from this generation either because of a call to RemoveObject
+    // (or indirectly via MarkUsedLocked) inside NotifyExpiredLocked. Fortunately
+    // no objects can be added to this generation because it's not the newest
+    // generation. We depend on the fact that RemoveObject can only cause
+    // the indexes of objects in this generation to *decrease*, not increase.
+    // So if we start from the end and work our way backwards we are guaranteed
+    // to see each object at least once.
+    size_t index = generation.Length();
+    for (;;) {
+      // Objects could have been removed so index could be outside
+      // the array
+      index = XPCOM_MIN(index, generation.Length());
+      if (index == 0) {
+        break;
+      }
+      --index;
+      NotifyExpiredLocked(generation[index], aAutoLock);
+    }
+    // Any leftover objects from reapGeneration just end up in the new
+    // newest-generation. This is bad form, though, so warn if there are any.
+    if (!generation.IsEmpty()) {
+      NS_WARNING("Expired objects were not removed or marked used");
+    }
+    // Free excess memory used by the generation array, since we probably
+    // just removed most or all of its elements.
+    generation.Compact();
+    mNewestGeneration = reapGeneration;
+    mInAgeOneGeneration = false;
+  }
+
+  /**
+   * This just calls AgeOneGenerationLocked K times. Under normal circumstances
+   * this will result in all objects getting NotifyExpiredLocked called on them,
+   * but if NotifyExpiredLocked itself marks some objects as used, then those
+   * objects might not expire. This would be a good thing to call if we get into
+   * a critically-low memory situation.
+   */
+  void AgeAllGenerationsLocked(const AutoLock& aAutoLock)
+  {
+    uint32_t i;
+    for (i = 0; i < K; ++i) {
+      AgeOneGenerationLocked(aAutoLock);
+    }
+  }
+
+  class Iterator
+  {
+  private:
+    ExpirationTrackerImpl<T, K, Mutex, AutoLock>* mTracker;
+    uint32_t mGeneration;
+    uint32_t mIndex;
+  public:
+    Iterator(ExpirationTrackerImpl<T, K, Mutex, AutoLock>* aTracker,
+             AutoLock& aAutoLock)
+      : mTracker(aTracker)
+      , mGeneration(0)
+      , mIndex(0)
+    {
+    }
+
+    T* Next()
+    {
+      while (mGeneration < K) {
+        nsTArray<T*>* generation = &mTracker->mGenerations[mGeneration];
+        if (mIndex < generation->Length()) {
+          ++mIndex;
+          return (*generation)[mIndex - 1];
+        }
+        ++mGeneration;
+        mIndex = 0;
+      }
+      return nullptr;
+    }
+  };
+
+  friend class Iterator;
+
+  bool IsEmptyLocked(const AutoLock& aAutoLock)
+  {
+    for (uint32_t i = 0; i < K; ++i) {
+      if (!mGenerations[i].IsEmpty()) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+protected:
+  /**
+   * This must be overridden to catch notifications. It is called whenever
+   * we detect that an object has not been used for at least (K-1)*mTimerPeriod
+   * milliseconds. If timer events are not delayed, it will be called within
+   * roughly K*mTimerPeriod milliseconds after the last use.
+   * (Unless AgeOneGenerationLocked or AgeAllGenerationsLocked have been called
+   * to accelerate the aging process.)
+   *
+   * NOTE: These bounds ignore delays in timer firings due to actual work being
+   * performed by the browser. We use a slack timer so there is always at least
+   * mTimerPeriod milliseconds between firings, which gives us (K-1)*mTimerPeriod
+   * as a pretty solid lower bound. The upper bound is rather loose, however.
+   * If the maximum amount by which any given timer firing is delayed is D, then
+   * the upper bound before NotifyExpiredLocked is called is K*(mTimerPeriod + D).
+   *
+   * The NotifyExpiredLocked call is expected to remove the object from the tracker,
+   * but it need not. The object (or other objects) could be "resurrected"
+   * by calling MarkUsedLocked() on them, or they might just not be removed.
+   * Any objects left over that have not been resurrected or removed
+   * are placed in the new newest-generation, but this is considered "bad form"
+   * and should be avoided (we'll issue a warning). (This recycling counts
+   * as "a use" for the purposes of the expiry guarantee above...)
+   *
+   * For robustness and simplicity, we allow objects to be notified more than
+   * once here in the same timer tick.
+   */
+  virtual void NotifyExpiredLocked(T*, const AutoLock&) = 0;
+
+  virtual Mutex& GetMutex() = 0;
+
+private:
+  class ExpirationTrackerObserver;
+  RefPtr<ExpirationTrackerObserver> mObserver;
+  nsTArray<T*>       mGenerations[K];
+  nsCOMPtr<nsITimer> mTimer;
+  uint32_t           mTimerPeriod;
+  uint32_t           mNewestGeneration;
+  bool               mInAgeOneGeneration;
+  const char* const  mName;   // Used for timer firing profiling.
+
+  /**
+   * Whenever "memory-pressure" is observed, it calls AgeAllGenerationsLocked()
+   * to minimize memory usage.
+   */
+  class ExpirationTrackerObserver final : public nsIObserver
+  {
+  public:
+    void Init(ExpirationTrackerImpl<T, K, Mutex, AutoLock>* aObj)
+    {
+      mOwner = aObj;
+      nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
+      if (obs) {
+        obs->AddObserver(this, "memory-pressure", false);
+      }
+    }
+    void Destroy()
+    {
+      mOwner = nullptr;
+      nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
+      if (obs) {
+        obs->RemoveObserver(this, "memory-pressure");
+      }
+    }
+    NS_DECL_ISUPPORTS
+    NS_DECL_NSIOBSERVER
+  private:
+    ExpirationTrackerImpl<T, K, Mutex, AutoLock>* mOwner;
+  };
+
+  void HandleLowMemory() {
+    AutoLock lock(GetMutex());
+    AgeAllGenerationsLocked(lock);
+  }
+
+  void HandleTimeout() {
+    AutoLock lock(GetMutex());
+    AgeOneGenerationLocked(lock);
+    // Cancel the timer if we have no objects to track
+    if (IsEmptyLocked(lock)) {
+      mTimer->Cancel();
+      mTimer = nullptr;
+    }
+  }
+
+  static void TimerCallback(nsITimer* aTimer, void* aThis)
+  {
+    ExpirationTrackerImpl* tracker = static_cast<ExpirationTrackerImpl*>(aThis);
+    tracker->HandleTimeout();
+  }
+
+  nsresult CheckStartTimerLocked(const AutoLock& aAutoLock)
+  {
+    if (mTimer || !mTimerPeriod) {
+      return NS_OK;
+    }
+    mTimer = do_CreateInstance("@mozilla.org/timer;1");
+    if (!mTimer) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    if (!NS_IsMainThread()) {
+      // TimerCallback should always be run on the main thread to prevent races
+      // to the destruction of the tracker.
+      nsCOMPtr<nsIEventTarget> target = do_GetMainThread();
+      NS_ENSURE_STATE(target);
+      mTimer->SetTarget(target);
+    }
+    mTimer->InitWithNamedFuncCallback(TimerCallback, this, mTimerPeriod,
+                                      nsITimer::TYPE_REPEATING_SLACK, mName);
+    return NS_OK;
+  }
+};
+
+namespace detail {
+
+class PlaceholderLock {
+public:
+  void Lock() {}
+  void Unlock() {}
+};
+
+class PlaceholderAutoLock {
+public:
+  explicit PlaceholderAutoLock(PlaceholderLock&) { }
+  ~PlaceholderAutoLock() = default;
+
+};
+
+template<typename T, uint32_t K>
+using SingleThreadedExpirationTracker =
+  ExpirationTrackerImpl<T, K, PlaceholderLock, PlaceholderAutoLock>;
+
+} // namespace detail
+
+template<typename T, uint32_t K>
+class nsExpirationTracker : protected ::detail::SingleThreadedExpirationTracker<T, K>
+{
+  typedef ::detail::PlaceholderLock Lock;
+  typedef ::detail::PlaceholderAutoLock AutoLock;
+
+  Lock mLock;
+
+  AutoLock FakeLock() {
+    return AutoLock(mLock);
+  }
+
+  Lock& GetMutex() override
+  {
+    return mLock;
+  }
+
+  void NotifyExpiredLocked(T* aObject, const AutoLock&) override
+  {
+    NotifyExpired(aObject);
+  }
+
+protected:
+  virtual void NotifyExpired(T* aObj) = 0;
+
+public:
+  nsExpirationTracker(uint32_t aTimerPeriod, const char* aName)
+    : ::detail::SingleThreadedExpirationTracker<T, K>(aTimerPeriod, aName)
+  { }
+
+  virtual ~nsExpirationTracker()
+  { }
+
+  nsresult AddObject(T* aObj)
+  {
+    return this->AddObjectLocked(aObj, FakeLock());
+  }
+
+  void RemoveObject(T* aObj)
+  {
+    this->RemoveObjectLocked(aObj, FakeLock());
+  }
+
+  nsresult MarkUsed(T* aObj)
+  {
+    return this->MarkUsedLocked(aObj, FakeLock());
+  }
+
+  void AgeOneGeneration()
+  {
+    this->AgeOneGenerationLocked(FakeLock());
+  }
+
+  void AgeAllGenerations()
+  {
+    this->AgeAllGenerationsLocked(FakeLock());
+  }
+
+  class Iterator
+  {
+  private:
+    AutoLock mAutoLock;
+    typename ExpirationTrackerImpl<T, K, Lock, AutoLock>::Iterator mIterator;
+  public:
+    explicit Iterator(nsExpirationTracker<T, K>* aTracker)
+      : mAutoLock(aTracker->GetMutex())
+      , mIterator(aTracker, mAutoLock)
+    {
+    }
+
+    T* Next()
+    {
+      return mIterator.Next();
+    }
+  };
+
+  friend class Iterator;
+
+  bool IsEmpty()
+  {
+    return this->IsEmptyLocked(FakeLock());
+  }
+};
+
+template<typename T, uint32_t K, typename Mutex, typename AutoLock>
+NS_IMETHODIMP
+ExpirationTrackerImpl<T, K, Mutex, AutoLock>::
+ExpirationTrackerObserver::Observe(
+    nsISupports* aSubject, const char* aTopic, const char16_t* aData)
+{
+  if (!strcmp(aTopic, "memory-pressure") && mOwner) {
+    mOwner->HandleLowMemory();
+  }
+  return NS_OK;
+}
+
+template<class T, uint32_t K, typename Mutex, typename AutoLock>
+NS_IMETHODIMP_(MozExternalRefCountType)
+ExpirationTrackerImpl<T, K, Mutex, AutoLock>::
+ExpirationTrackerObserver::AddRef(void)
+{
+  MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");
+  NS_ASSERT_OWNINGTHREAD(ExpirationTrackerObserver);
+  ++mRefCnt;
+  NS_LOG_ADDREF(this, mRefCnt, "ExpirationTrackerObserver", sizeof(*this));
+  return mRefCnt;
+}
+
+template<class T, uint32_t K, typename Mutex, typename AutoLock>
+NS_IMETHODIMP_(MozExternalRefCountType)
+ExpirationTrackerImpl<T, K, Mutex, AutoLock>::
+ExpirationTrackerObserver::Release(void)
+{
+  MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");
+  NS_ASSERT_OWNINGTHREAD(ExpirationTrackerObserver);
+  --mRefCnt;
+  NS_LOG_RELEASE(this, mRefCnt, "ExpirationTrackerObserver");
+  if (mRefCnt == 0) {
+    NS_ASSERT_OWNINGTHREAD(ExpirationTrackerObserver);
+    mRefCnt = 1; /* stabilize */
+    delete (this);
+    return 0;
+  }
+  return mRefCnt;
+}
+
+template<class T, uint32_t K, typename Mutex, typename AutoLock>
+NS_IMETHODIMP
+ExpirationTrackerImpl<T, K, Mutex, AutoLock>::
+ExpirationTrackerObserver::QueryInterface(
+    REFNSIID aIID, void** aInstancePtr)
+{
+  NS_ASSERTION(aInstancePtr,
+               "QueryInterface requires a non-NULL destination!");
+  nsresult rv = NS_ERROR_FAILURE;
+  NS_INTERFACE_TABLE(ExpirationTrackerObserver, nsIObserver)
+  return rv;
+}
+
+#endif /*NSEXPIRATIONTRACKER_H_*/
diff --git a/xpcom/ds/nsHashPropertyBag.cpp b/xpcom/ds/nsHashPropertyBag.cpp
new file mode 100644
index 000000000..6f9fc8dec
--- /dev/null
+++ b/xpcom/ds/nsHashPropertyBag.cpp
@@ -0,0 +1,284 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsHashPropertyBag.h"
+#include "nsArray.h"
+#include "nsArrayEnumerator.h"
+#include "nsIVariant.h"
+#include "nsIProperty.h"
+#include "nsVariant.h"
+#include "mozilla/Attributes.h"
+
+/*
+ * nsHashPropertyBagBase implementation.
+ */
+
+NS_IMETHODIMP
+nsHashPropertyBagBase::HasKey(const nsAString& aName, bool* aResult)
+{
+  *aResult = mPropertyHash.Get(aName, nullptr);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsHashPropertyBagBase::Get(const nsAString& aName, nsIVariant** aResult)
+{
+  if (!mPropertyHash.Get(aName, aResult)) {
+    *aResult = nullptr;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsHashPropertyBagBase::GetProperty(const nsAString& aName, nsIVariant** aResult)
+{
+  bool isFound = mPropertyHash.Get(aName, aResult);
+  if (!isFound) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsHashPropertyBagBase::SetProperty(const nsAString& aName, nsIVariant* aValue)
+{
+  if (NS_WARN_IF(!aValue)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  mPropertyHash.Put(aName, aValue);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsHashPropertyBagBase::DeleteProperty(const nsAString& aName)
+{
+  // is it too much to ask for ns*Hashtable to return
+  // a boolean indicating whether RemoveEntry succeeded
+  // or not?!?!
+  bool isFound = mPropertyHash.Get(aName, nullptr);
+  if (!isFound) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // then from the hash
+  mPropertyHash.Remove(aName);
+
+  return NS_OK;
+}
+
+
+//
+// nsSimpleProperty class and impl; used for GetEnumerator
+//
+
+class nsSimpleProperty final : public nsIProperty
+{
+  ~nsSimpleProperty() {}
+
+public:
+  nsSimpleProperty(const nsAString& aName, nsIVariant* aValue)
+    : mName(aName)
+    , mValue(aValue)
+  {
+  }
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIPROPERTY
+protected:
+  nsString mName;
+  nsCOMPtr<nsIVariant> mValue;
+};
+
+NS_IMPL_ISUPPORTS(nsSimpleProperty, nsIProperty)
+
+NS_IMETHODIMP
+nsSimpleProperty::GetName(nsAString& aName)
+{
+  aName.Assign(mName);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSimpleProperty::GetValue(nsIVariant** aValue)
+{
+  NS_IF_ADDREF(*aValue = mValue);
+  return NS_OK;
+}
+
+// end nsSimpleProperty
+
+NS_IMETHODIMP
+nsHashPropertyBagBase::GetEnumerator(nsISimpleEnumerator** aResult)
+{
+  nsCOMPtr<nsIMutableArray> propertyArray = nsArray::Create();
+  if (!propertyArray) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  for (auto iter = mPropertyHash.Iter(); !iter.Done(); iter.Next()) {
+    const nsAString& key = iter.Key();
+    nsIVariant* data = iter.UserData();
+    nsSimpleProperty* sprop = new nsSimpleProperty(key, data);
+    propertyArray->AppendElement(sprop, false);
+  }
+
+  return NS_NewArrayEnumerator(aResult, propertyArray);
+}
+
+#define IMPL_GETSETPROPERTY_AS(Name, Type) \
+NS_IMETHODIMP \
+nsHashPropertyBagBase::GetPropertyAs ## Name (const nsAString & prop, Type *_retval) \
+{ \
+    nsIVariant* v = mPropertyHash.GetWeak(prop); \
+    if (!v) \
+        return NS_ERROR_NOT_AVAILABLE; \
+    return v->GetAs ## Name(_retval); \
+} \
+\
+NS_IMETHODIMP \
+nsHashPropertyBagBase::SetPropertyAs ## Name (const nsAString & prop, Type value) \
+{ \
+    nsCOMPtr<nsIWritableVariant> var = new nsVariant(); \
+    var->SetAs ## Name(value); \
+    return SetProperty(prop, var); \
+}
+
+IMPL_GETSETPROPERTY_AS(Int32, int32_t)
+IMPL_GETSETPROPERTY_AS(Uint32, uint32_t)
+IMPL_GETSETPROPERTY_AS(Int64, int64_t)
+IMPL_GETSETPROPERTY_AS(Uint64, uint64_t)
+IMPL_GETSETPROPERTY_AS(Double, double)
+IMPL_GETSETPROPERTY_AS(Bool, bool)
+
+
+NS_IMETHODIMP
+nsHashPropertyBagBase::GetPropertyAsAString(const nsAString& aProp,
+                                            nsAString& aResult)
+{
+  nsIVariant* v = mPropertyHash.GetWeak(aProp);
+  if (!v) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+  return v->GetAsAString(aResult);
+}
+
+NS_IMETHODIMP
+nsHashPropertyBagBase::GetPropertyAsACString(const nsAString& aProp,
+                                             nsACString& aResult)
+{
+  nsIVariant* v = mPropertyHash.GetWeak(aProp);
+  if (!v) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+  return v->GetAsACString(aResult);
+}
+
+NS_IMETHODIMP
+nsHashPropertyBagBase::GetPropertyAsAUTF8String(const nsAString& aProp,
+                                                nsACString& aResult)
+{
+  nsIVariant* v = mPropertyHash.GetWeak(aProp);
+  if (!v) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+  return v->GetAsAUTF8String(aResult);
+}
+
+NS_IMETHODIMP
+nsHashPropertyBagBase::GetPropertyAsInterface(const nsAString& aProp,
+                                              const nsIID& aIID,
+                                              void** aResult)
+{
+  nsIVariant* v = mPropertyHash.GetWeak(aProp);
+  if (!v) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+  nsCOMPtr<nsISupports> val;
+  nsresult rv = v->GetAsISupports(getter_AddRefs(val));
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (!val) {
+    // We have a value, but it's null
+    *aResult = nullptr;
+    return NS_OK;
+  }
+  return val->QueryInterface(aIID, aResult);
+}
+
+NS_IMETHODIMP
+nsHashPropertyBagBase::SetPropertyAsAString(const nsAString& aProp,
+                                            const nsAString& aValue)
+{
+  nsCOMPtr<nsIWritableVariant> var = new nsVariant();
+  var->SetAsAString(aValue);
+  return SetProperty(aProp, var);
+}
+
+NS_IMETHODIMP
+nsHashPropertyBagBase::SetPropertyAsACString(const nsAString& aProp,
+                                             const nsACString& aValue)
+{
+  nsCOMPtr<nsIWritableVariant> var = new nsVariant();
+  var->SetAsACString(aValue);
+  return SetProperty(aProp, var);
+}
+
+NS_IMETHODIMP
+nsHashPropertyBagBase::SetPropertyAsAUTF8String(const nsAString& aProp,
+                                                const nsACString& aValue)
+{
+  nsCOMPtr<nsIWritableVariant> var = new nsVariant();
+  var->SetAsAUTF8String(aValue);
+  return SetProperty(aProp, var);
+}
+
+NS_IMETHODIMP
+nsHashPropertyBagBase::SetPropertyAsInterface(const nsAString& aProp,
+                                              nsISupports* aValue)
+{
+  nsCOMPtr<nsIWritableVariant> var = new nsVariant();
+  var->SetAsISupports(aValue);
+  return SetProperty(aProp, var);
+}
+
+
+/*
+ * nsHashPropertyBag implementation.
+ */
+
+NS_IMPL_ADDREF(nsHashPropertyBag)
+NS_IMPL_RELEASE(nsHashPropertyBag)
+
+NS_INTERFACE_MAP_BEGIN(nsHashPropertyBag)
+  NS_INTERFACE_MAP_ENTRY(nsIWritablePropertyBag)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsIPropertyBag, nsIWritablePropertyBag)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIWritablePropertyBag)
+  NS_INTERFACE_MAP_ENTRY(nsIPropertyBag2)
+  NS_INTERFACE_MAP_ENTRY(nsIWritablePropertyBag2)
+NS_INTERFACE_MAP_END
+
+
+/*
+ * nsHashPropertyBagCC implementation.
+ */
+
+NS_IMPL_CYCLE_COLLECTION(nsHashPropertyBagCC, mPropertyHash)
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(nsHashPropertyBagCC)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(nsHashPropertyBagCC)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsHashPropertyBagCC)
+  NS_INTERFACE_MAP_ENTRY(nsIWritablePropertyBag)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsIPropertyBag, nsIWritablePropertyBag)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIWritablePropertyBag)
+  NS_INTERFACE_MAP_ENTRY(nsIPropertyBag2)
+  NS_INTERFACE_MAP_ENTRY(nsIWritablePropertyBag2)
+NS_INTERFACE_MAP_END
diff --git a/xpcom/ds/nsHashPropertyBag.h b/xpcom/ds/nsHashPropertyBag.h
new file mode 100644
index 000000000..e41c984ba
--- /dev/null
+++ b/xpcom/ds/nsHashPropertyBag.h
@@ -0,0 +1,57 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsHashPropertyBag_h___
+#define nsHashPropertyBag_h___
+
+#include "nsIVariant.h"
+#include "nsIWritablePropertyBag.h"
+#include "nsIWritablePropertyBag2.h"
+
+#include "nsCycleCollectionParticipant.h"
+#include "nsInterfaceHashtable.h"
+
+class nsHashPropertyBagBase
+  : public nsIWritablePropertyBag
+  , public nsIWritablePropertyBag2
+{
+public:
+  nsHashPropertyBagBase() {}
+
+  NS_DECL_NSIPROPERTYBAG
+  NS_DECL_NSIPROPERTYBAG2
+
+  NS_DECL_NSIWRITABLEPROPERTYBAG
+  NS_DECL_NSIWRITABLEPROPERTYBAG2
+
+protected:
+  // a hash table of string -> nsIVariant
+  nsInterfaceHashtable<nsStringHashKey, nsIVariant> mPropertyHash;
+};
+
+class nsHashPropertyBag : public nsHashPropertyBagBase
+{
+public:
+  nsHashPropertyBag() {}
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+protected:
+  virtual ~nsHashPropertyBag() {}
+};
+
+/* A cycle collected nsHashPropertyBag for main-thread-only use. */
+class nsHashPropertyBagCC final : public nsHashPropertyBagBase
+{
+public:
+  nsHashPropertyBagCC() {}
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(nsHashPropertyBagCC,
+                                           nsIWritablePropertyBag)
+protected:
+  virtual ~nsHashPropertyBagCC() {}
+};
+
+#endif /* nsHashPropertyBag_h___ */
diff --git a/xpcom/ds/nsIArray.idl b/xpcom/ds/nsIArray.idl
new file mode 100644
index 000000000..d591253e9
--- /dev/null
+++ b/xpcom/ds/nsIArray.idl
@@ -0,0 +1,91 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsISimpleEnumerator;
+
+/**
+ * nsIArray
+ *
+ * An indexed collection of elements. Provides basic functionality for
+ * retrieving elements at a specific position, searching for
+ * elements. Indexes are zero-based, such that the last element in the
+ * array is stored at the index length-1.
+ *
+ * For an array which can be modified, see nsIMutableArray below.
+ *
+ * Neither interface makes any attempt to protect the individual
+ * elements from modification. The convention is that the elements of
+ * the array should not be modified. Documentation within a specific
+ * interface should describe variations from this convention.
+ *
+ * It is also convention that if an interface provides access to an
+ * nsIArray, that the array should not be QueryInterfaced to an
+ * nsIMutableArray for modification. If the interface in question had
+ * intended the array to be modified, it would have returned an
+ * nsIMutableArray!
+ *
+ * null is a valid entry in the array, and as such any nsISupports
+ * parameters may be null, except where noted.
+ */
+[scriptable, uuid(114744d9-c369-456e-b55a-52fe52880d2d)]
+interface nsIArray : nsISupports
+{
+    /**
+     * length
+     *
+     * number of elements in the array.
+     */
+    readonly attribute unsigned long length;
+
+    /**
+     * queryElementAt()
+     *
+     * Retrieve a specific element of the array, and QueryInterface it
+     * to the specified interface. null is a valid result for
+     * this method, but exceptions are thrown in other circumstances
+     * 
+     * @param index position of element
+     * @param uuid the IID of the requested interface
+     * @param result the object, QI'd to the requested interface
+     *
+     * @throws NS_ERROR_NO_INTERFACE when an entry exists at the
+     *         specified index, but the requested interface is not
+     *         available.
+     * @throws NS_ERROR_ILLEGAL_VALUE when index > length-1
+     *
+     */
+    void queryElementAt(in unsigned long index,
+                        in nsIIDRef uuid,
+                        [iid_is(uuid), retval] out nsQIResult result);
+    
+    /**
+     * indexOf()
+     * 
+     * Get the position of a specific element. Note that since null is
+     * a valid input, exceptions are used to indicate that an element
+     * is not found.
+     * 
+     * @param startIndex The initial element to search in the array
+     *                   To start at the beginning, use 0 as the
+     *                   startIndex
+     * @param element    The element you are looking for
+     * @returns a number >= startIndex which is the position of the
+     *          element in the array.
+     * @throws NS_ERROR_FAILURE if the element was not in the array.
+     */
+    unsigned long indexOf(in unsigned long startIndex,
+                          in nsISupports element);
+
+    /**
+     * enumerate the array
+     *
+     * @returns a new enumerator positioned at the start of the array
+     * @throws NS_ERROR_FAILURE if the array is empty (to make it easy
+     *         to detect errors), or NS_ERROR_OUT_OF_MEMORY if out of memory.
+     */
+    nsISimpleEnumerator enumerate();
+};
diff --git a/xpcom/ds/nsIArrayExtensions.idl b/xpcom/ds/nsIArrayExtensions.idl
new file mode 100644
index 000000000..3682d2ee7
--- /dev/null
+++ b/xpcom/ds/nsIArrayExtensions.idl
@@ -0,0 +1,51 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIArray.idl"
+
+/**
+ * Helper interface for allowing scripts to treat nsIArray instances as if
+ * they were nsISupportsArray instances while iterating.
+ *
+ * nsISupportsArray is convenient to iterate over in JavaScript:
+ *
+ * for (let i = 0; i < array.Count(); ++i) {
+ *   let elem = array.GetElementAt(i);
+ *   ...
+ * }
+ *
+ * but doing the same with nsIArray is somewhat less convenient, since
+ * queryElementAt is not nearly so nice to use from JavaScript.  So we provide
+ * this extension interface so interfaces that currently return
+ * nsISupportsArray can start returning nsIArrayExtensions and all JavaScript
+ * should Just Work. Eventually we'll roll this interface into nsIArray
+ * itself, possibly getting rid of the Count() method, as it duplicates
+ * nsIArray functionality.
+ */
+[scriptable, uuid(261d442e-050c-453d-8aaa-b3f23bcc528b)]
+interface nsIArrayExtensions : nsIArray
+{
+  /**
+   * Count()
+   *
+   * Retrieves the length of the array. This is an alias for the
+   * |nsIArray.length| attribute.
+   */
+  uint32_t Count();
+
+  /**
+   * GetElementAt()
+   *
+   * Retrieve a specific element of the array. null is a valid result for
+   * this method.
+   *
+   * Note: If the index is out of bounds null will be returned.
+   *       This differs from the behavior of nsIArray.queryElementAt() which
+   *       will throw if an invalid index is specified.
+   *
+   * @param index position of element
+   */
+  nsISupports GetElementAt(in uint32_t index);
+};
diff --git a/xpcom/ds/nsIAtom.idl b/xpcom/ds/nsIAtom.idl
new file mode 100644
index 000000000..c02540838
--- /dev/null
+++ b/xpcom/ds/nsIAtom.idl
@@ -0,0 +1,166 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include "nsISupports.idl"
+
+%{C++
+#include "nsStringGlue.h"
+#include "nsCOMPtr.h"
+#include "nsStringBuffer.h"
+%}
+
+native MallocSizeOf(mozilla::MallocSizeOf);
+
+/*
+ * Should this really be scriptable?  Using atoms from script or proxies
+ * could be dangerous since double-wrapping could lead to loss of
+ * pointer identity.
+ */
+ 
+[scriptable, builtinclass, uuid(8b8c11d4-3ed5-4079-8974-73c7576cdb34)]
+interface nsIAtom : nsISupports
+{
+  /**
+   * Get the Unicode or UTF8 value for the string
+   */
+  [binaryname(ScriptableToString)] AString toString(); 
+  [noscript] AUTF8String toUTF8String();
+  
+  /**
+   * Compare the atom to a specific string value
+   * Note that this will NEVER return/throw an error condition.
+   */
+  [binaryname(ScriptableEquals)] boolean equals(in AString aString);
+
+  [noscript, notxpcom]
+  size_t SizeOfIncludingThis(in MallocSizeOf aMallocSizeOf);
+
+%{C++
+  // note this is NOT virtual so this won't muck with the vtable!
+  inline bool Equals(const nsAString& aString) const {
+    return aString.Equals(nsDependentString(mString, mLength));
+  }
+
+  inline bool IsStaticAtom() const {
+    return mIsStatic;
+  }
+
+  inline char16ptr_t GetUTF16String() const {
+    return mString;
+  }
+
+  inline uint32_t GetLength() const {
+    return mLength;
+  }
+
+  inline void ToString(nsAString& aBuf) {
+    // See the comment on |mString|'s declaration.
+    nsStringBuffer::FromData(mString)->ToString(mLength, aBuf);
+  }
+
+  inline nsStringBuffer* GetStringBuffer() const {
+    // See the comment on |mString|'s declaration.
+    return nsStringBuffer::FromData(mString);
+  }
+
+  /**
+   * A hashcode that is better distributed than the actual atom
+   * pointer, for use in situations that need a well-distributed
+   * hashcode.
+   */
+  inline uint32_t hash() const {
+    return mHash;
+  }
+
+protected:
+  uint32_t mLength:31;
+  uint32_t mIsStatic:1;
+  uint32_t mHash;
+  /**
+   * WARNING! There is an invisible constraint on |mString|: the chars it
+   * points to must belong to an nsStringBuffer. This is so that the
+   * nsStringBuffer::FromData() calls above are valid.
+   */
+  char16_t* mString;
+%}
+};
+
+
+%{C++
+/*
+ * The four forms of NS_Atomize (for use with |nsCOMPtr<nsIAtom>|) return the
+ * atom for the string given. At any given time there will always be one atom
+ * representing a given string. Atoms are intended to make string comparison
+ * cheaper by simplifying it to pointer equality. A pointer to the atom that
+ * does not own a reference is not guaranteed to be valid.
+ */
+
+
+/**
+ * Find an atom that matches the given UTF-8 string.
+ * The string is assumed to be zero terminated.  Never returns null.
+ */
+extern already_AddRefed<nsIAtom> NS_Atomize(const char* aUTF8String);
+
+/**
+ * Find an atom that matches the given UTF-8 string.  Never returns null.
+ */
+extern already_AddRefed<nsIAtom> NS_Atomize(const nsACString& aUTF8String);
+
+/**
+ * Find an atom that matches the given UTF-16 string.
+ * The string is assumed to be zero terminated.  Never returns null.
+ */
+extern already_AddRefed<nsIAtom> NS_Atomize(const char16_t* aUTF16String);
+
+/**
+ * Find an atom that matches the given UTF-16 string.  Never returns null.
+ */
+extern already_AddRefed<nsIAtom> NS_Atomize(const nsAString& aUTF16String);
+
+/**
+ * Return a count of the total number of atoms currently
+ * alive in the system.
+ */
+extern nsrefcnt NS_GetNumberOfAtoms(void);
+
+/**
+ * Return a pointer for a static atom for the string or null if there's 
+ * no static atom for this string.
+ */
+extern nsIAtom* NS_GetStaticAtom(const nsAString& aUTF16String);
+
+/**
+ * Seal the static atom table
+ */
+extern void NS_SealStaticAtomTable();
+
+class nsAtomString : public nsString
+{
+public:
+  explicit nsAtomString(nsIAtom* aAtom)
+  {
+    aAtom->ToString(*this);
+  }
+};
+
+class nsAtomCString : public nsCString
+{
+public:
+  explicit nsAtomCString(nsIAtom* aAtom)
+  {
+    aAtom->ToUTF8String(*this);
+  }
+};
+
+class nsDependentAtomString : public nsDependentString
+{
+public:
+  explicit nsDependentAtomString(nsIAtom* aAtom)
+    : nsDependentString(aAtom->GetUTF16String(), aAtom->GetLength())
+  {
+  }
+};
+
+%}
diff --git a/xpcom/ds/nsIAtomService.idl b/xpcom/ds/nsIAtomService.idl
new file mode 100644
index 000000000..a7885a413
--- /dev/null
+++ b/xpcom/ds/nsIAtomService.idl
@@ -0,0 +1,35 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIAtom;
+
+%{C++
+#define NS_ATOMSERVICE_CID \
+{ /* ed3db3fc-0168-4cab-8818-98f5475a490c */ \
+    0xed3db3fc,                              \
+    0x0168,                                  \
+    0x4cab,                                  \
+    {0x88, 0x18, 0x98, 0xf5, 0x47, 0x5a, 0x49, 0x0c} }
+
+#define NS_ATOMSERVICE_CONTRACTID "@mozilla.org/atom-service;1"
+%}
+
+/*
+ * Should this really be scriptable?  Using atoms from script or proxies
+ * could be dangerous since double-wrapping could lead to loss of
+ * pointer identity.
+ */
+ 
+[scriptable, uuid(9c1f50b9-f9eb-42d4-a8cb-2c7600aeb241)]
+interface nsIAtomService : nsISupports {
+
+  /**
+   * Version of NS_Atomize that doesn't require linking against the
+   * XPCOM library.  See nsIAtom.idl.
+   */
+  nsIAtom getAtom(in AString value);
+};
diff --git a/xpcom/ds/nsICollection.idl b/xpcom/ds/nsICollection.idl
new file mode 100644
index 000000000..3cd851419
--- /dev/null
+++ b/xpcom/ds/nsICollection.idl
@@ -0,0 +1,67 @@
+/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISerializable.idl"
+
+interface nsIEnumerator;
+
+[deprecated, scriptable, uuid(83b6019c-cbc4-11d2-8cca-0060b0fc14a3)]
+interface nsICollection : nsISerializable
+{
+
+  uint32_t Count();
+  nsISupports GetElementAt(in uint32_t index);
+  void QueryElementAt(in uint32_t index, in nsIIDRef uuid, 
+                      [iid_is(uuid),retval] out nsQIResult result);
+  void SetElementAt(in uint32_t index, in nsISupports item);
+  void AppendElement(in nsISupports item);
+  void RemoveElement(in nsISupports item);
+
+  /**
+   * This clashes with |nsISimpleEnumerator nsIArray.enumerate()| (only on the
+   * binary side), so it is renamed with a 'Deprecated' prefix in favor of the
+   * non-deprecated |nsIArray.enumerate|.
+   */
+  [binaryname(DeprecatedEnumerate)]
+  nsIEnumerator Enumerate();
+
+  void Clear();
+
+};
+
+%{C++
+
+#ifndef nsCOMPtr_h__
+#include "nsCOMPtr.h"
+#endif
+
+class MOZ_STACK_CLASS nsQueryElementAt : public nsCOMPtr_helper
+  {
+    public:
+      nsQueryElementAt( nsICollection* aCollection, uint32_t aIndex, nsresult* aErrorPtr )
+          : mCollection(aCollection),
+            mIndex(aIndex),
+            mErrorPtr(aErrorPtr)
+        {
+          // nothing else to do here
+        }
+
+      virtual nsresult NS_FASTCALL operator()( const nsIID& aIID, void** )
+        const override;
+
+    private:
+      nsICollection* MOZ_NON_OWNING_REF mCollection;
+      uint32_t        mIndex;
+      nsresult*       mErrorPtr;
+  };
+
+inline
+const nsQueryElementAt
+do_QueryElementAt( nsICollection* aCollection, uint32_t aIndex, nsresult* aErrorPtr = 0 )
+  {
+    return nsQueryElementAt(aCollection, aIndex, aErrorPtr);
+  }
+
+%}
diff --git a/xpcom/ds/nsIEnumerator.idl b/xpcom/ds/nsIEnumerator.idl
new file mode 100644
index 000000000..9482ef436
--- /dev/null
+++ b/xpcom/ds/nsIEnumerator.idl
@@ -0,0 +1,50 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+%{C++
+#define NS_ENUMERATOR_FALSE 1
+%}
+/*
+ * DO NOT USE THIS INTERFACE.  IT IS HORRIBLY BROKEN, USES NS_COMFALSE
+ * AND IS BASICALLY IMPOSSIBLE TO USE CORRECTLY THROUGH PROXIES OR
+ * XPCONNECT.  IF YOU SEE NEW USES OF THIS INTERFACE IN CODE YOU ARE
+ * REVIEWING, YOU SHOULD INSIST ON nsISimpleEnumerator.
+ *
+ * DON'T MAKE ME COME OVER THERE.
+ */
+[deprecated, scriptable, uuid(ad385286-cbc4-11d2-8cca-0060b0fc14a3)]
+interface nsIEnumerator : nsISupports {
+  /** First will reset the list. will return NS_FAILED if no items
+   */
+  void first();
+
+  /** Next will advance the list. will return failed if already at end
+   */
+  void next();
+
+  /** CurrentItem will return the CurrentItem item it will fail if the 
+   *  list is empty
+   */
+  nsISupports currentItem();
+
+  /** return if the collection is at the end.  that is the beginning following 
+   *  a call to Prev and it is the end of the list following a call to next
+   */
+  void isDone();
+};
+
+[deprecated, uuid(75f158a0-cadd-11d2-8cca-0060b0fc14a3)]
+interface nsIBidirectionalEnumerator : nsIEnumerator {
+
+  /** Last will reset the list to the end. will return NS_FAILED if no items
+   */
+  void last();
+
+  /** Prev will decrement the list. will return failed if already at beginning
+   */
+  void prev();
+};
diff --git a/xpcom/ds/nsIHashable.idl b/xpcom/ds/nsIHashable.idl
new file mode 100644
index 000000000..aa223787c
--- /dev/null
+++ b/xpcom/ds/nsIHashable.idl
@@ -0,0 +1,24 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * Represents an object that can be stored in a hashtable.
+ */
+[scriptable, uuid(17e595fa-b57a-4933-bd0f-b1812e8ab188)]
+interface nsIHashable : nsISupports
+{
+  /**
+   * Is this object the equivalent of the other object?
+   */
+  boolean equals(in nsIHashable aOther);
+
+  /**
+   * A generated hashcode for this object. Objects that are equivalent
+   * must have the same hash code. Getting this property should never
+   * throw an exception!
+   */
+  readonly attribute unsigned long hashCode;
+};
diff --git a/xpcom/ds/nsIINIParser.idl b/xpcom/ds/nsIINIParser.idl
new file mode 100644
index 000000000..166828e5d
--- /dev/null
+++ b/xpcom/ds/nsIINIParser.idl
@@ -0,0 +1,58 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIUTF8StringEnumerator;
+interface nsIFile;
+
+[scriptable, uuid(7eb955f6-3e78-4d39-b72f-c1bf12a94bce)]
+interface nsIINIParser : nsISupports
+{
+  /**
+   * Enumerates the [section]s available in the INI file.
+   */
+  nsIUTF8StringEnumerator getSections();
+
+  /**
+   * Enumerates the keys available within a section.
+   */
+  nsIUTF8StringEnumerator getKeys(in AUTF8String aSection);
+
+  /**
+   * Get the value of a string for a particular section and key.
+   */
+  AUTF8String getString(in AUTF8String aSection, in AUTF8String aKey);
+};
+
+[scriptable, uuid(b67bb24b-31a3-4a6a-a5d9-0485c9af5a04)]
+interface nsIINIParserWriter : nsISupports
+{
+  /**
+   * Windows and the NSIS installer code sometimes expect INI files to be in
+   * UTF-16 encoding. On Windows only, this flag to writeFile can be used to
+   * change the encoding from its default UTF-8.
+   */
+  const unsigned long WRITE_UTF16 = 0x1;
+
+  /**
+   * Set the value of a string for a particular section and key.
+   */
+  void setString(in AUTF8String aSection, in AUTF8String aKey, in AUTF8String aValue);
+
+  /**
+   * Write to the INI file.
+   */
+  void writeFile([optional] in nsIFile aINIFile,
+                 [optional] in unsigned long aFlags);
+};
+
+[scriptable, uuid(ccae7ea5-1218-4b51-aecb-c2d8ecd46af9)]
+interface nsIINIParserFactory : nsISupports
+{
+  /**
+   * Create an iniparser instance from a local file.
+   */
+  nsIINIParser createINIParser(in nsIFile aINIFile);
+};
diff --git a/xpcom/ds/nsIMutableArray.idl b/xpcom/ds/nsIMutableArray.idl
new file mode 100644
index 000000000..67e527a81
--- /dev/null
+++ b/xpcom/ds/nsIMutableArray.idl
@@ -0,0 +1,110 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIArrayExtensions.idl"
+
+/**
+ * nsIMutableArray
+ * A separate set of methods that will act on the array. Consumers of
+ * nsIArray should not QueryInterface to nsIMutableArray unless they
+ * own the array.
+ *
+ * As above, it is legal to add null elements to the array. Note also
+ * that null elements can be created as a side effect of
+ * insertElementAt(). Conversely, if insertElementAt() is never used,
+ * and null elements are never explicitly added to the array, then it
+ * is guaranteed that queryElementAt() will never return a null value.
+ *
+ * Any of these methods may throw NS_ERROR_OUT_OF_MEMORY when the
+ * array must grow to complete the call, but the allocation fails.
+ */
+[scriptable, uuid(af059da0-c85b-40ec-af07-ae4bfdc192cc)]
+interface nsIMutableArray : nsIArrayExtensions
+{
+    /**
+     * appendElement()
+     * 
+     * Append an element at the end of the array.
+     *
+     * @param element The element to append.
+     * @param weak    Whether or not to store the element using a weak
+     *                reference.
+     * @throws NS_ERROR_FAILURE when a weak reference is requested,
+     *                          but the element does not support
+     *                          nsIWeakReference.
+     */
+    void appendElement(in nsISupports element, in boolean weak);
+
+    /**
+     * removeElementAt()
+     * 
+     * Remove an element at a specific position, moving all elements
+     * stored at a higher position down one.
+     * To remove a specific element, use indexOf() to find the index
+     * first, then call removeElementAt().
+     *
+     * @param index the position of the item
+     *
+     */
+    void removeElementAt(in unsigned long index);
+
+    /**
+     * insertElementAt()
+     *
+     * Insert an element at the given position, moving the element 
+     * currently located in that position, and all elements in higher
+     * position, up by one.
+     *
+     * @param element The element to insert
+     * @param index   The position in the array:
+     *                If the position is lower than the current length
+     *                of the array, the elements at that position and
+     *                onwards are bumped one position up.
+     *                If the position is equal to the current length
+     *                of the array, the new element is appended.
+     *                An index lower than 0 or higher than the current
+     *                length of the array is invalid and will be ignored.
+     *
+     * @throws NS_ERROR_FAILURE when a weak reference is requested,
+     *                          but the element does not support
+     *                          nsIWeakReference.
+     */
+    void insertElementAt(in nsISupports element, in unsigned long index,
+                         in boolean weak);
+
+    /**
+     * replaceElementAt()
+     *
+     * Replace the element at the given position.
+     *
+     * @param element The new element to insert
+     * @param index   The position in the array
+     *                If the position is lower than the current length
+     *                of the array, an existing element will be replaced.
+     *                If the position is equal to the current length
+     *                of the array, the new element is appended.
+     *                If the position is higher than the current length
+     *                of the array, empty elements are appended followed
+     *                by the new element at the specified position.
+     *                An index lower than 0 is invalid and will be ignored.
+     *
+     * @param weak    Whether or not to store the new element using a weak
+     *                reference.
+     *
+     * @throws NS_ERROR_FAILURE when a weak reference is requested,
+     *                          but the element does not support
+     *                          nsIWeakReference.
+     */
+    void replaceElementAt(in nsISupports element, in unsigned long index,
+                          in boolean weak);
+    
+    
+    /**
+     * clear()
+     *
+     * clear the entire array, releasing all stored objects
+     */
+    void clear();
+};
diff --git a/xpcom/ds/nsINIParserImpl.cpp b/xpcom/ds/nsINIParserImpl.cpp
new file mode 100644
index 000000000..24def4e58
--- /dev/null
+++ b/xpcom/ds/nsINIParserImpl.cpp
@@ -0,0 +1,142 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsINIParserImpl.h"
+
+#include "nsINIParser.h"
+#include "nsStringEnumerator.h"
+#include "nsTArray.h"
+#include "mozilla/Attributes.h"
+
+class nsINIParserImpl final
+  : public nsIINIParser
+{
+  ~nsINIParserImpl() {}
+
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIINIPARSER
+
+  nsresult Init(nsIFile* aINIFile) { return mParser.Init(aINIFile); }
+
+private:
+  nsINIParser mParser;
+};
+
+NS_IMPL_ISUPPORTS(nsINIParserFactory,
+                  nsIINIParserFactory,
+                  nsIFactory)
+
+NS_IMETHODIMP
+nsINIParserFactory::CreateINIParser(nsIFile* aINIFile,
+                                    nsIINIParser** aResult)
+{
+  *aResult = nullptr;
+
+  RefPtr<nsINIParserImpl> p(new nsINIParserImpl());
+  if (!p) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  nsresult rv = p->Init(aINIFile);
+
+  if (NS_SUCCEEDED(rv)) {
+    NS_ADDREF(*aResult = p);
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsINIParserFactory::CreateInstance(nsISupports* aOuter,
+                                   REFNSIID aIID,
+                                   void** aResult)
+{
+  if (NS_WARN_IF(aOuter)) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+
+  // We are our own singleton.
+  return QueryInterface(aIID, aResult);
+}
+
+NS_IMETHODIMP
+nsINIParserFactory::LockFactory(bool aLock)
+{
+  return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS(nsINIParserImpl,
+                  nsIINIParser)
+
+static bool
+SectionCB(const char* aSection, void* aClosure)
+{
+  nsTArray<nsCString>* strings = static_cast<nsTArray<nsCString>*>(aClosure);
+  strings->AppendElement()->Assign(aSection);
+  return true;
+}
+
+NS_IMETHODIMP
+nsINIParserImpl::GetSections(nsIUTF8StringEnumerator** aResult)
+{
+  nsTArray<nsCString>* strings = new nsTArray<nsCString>;
+  if (!strings) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  nsresult rv = mParser.GetSections(SectionCB, strings);
+  if (NS_SUCCEEDED(rv)) {
+    rv = NS_NewAdoptingUTF8StringEnumerator(aResult, strings);
+  }
+
+  if (NS_FAILED(rv)) {
+    delete strings;
+  }
+
+  return rv;
+}
+
+static bool
+KeyCB(const char* aKey, const char* aValue, void* aClosure)
+{
+  nsTArray<nsCString>* strings = static_cast<nsTArray<nsCString>*>(aClosure);
+  strings->AppendElement()->Assign(aKey);
+  return true;
+}
+
+NS_IMETHODIMP
+nsINIParserImpl::GetKeys(const nsACString& aSection,
+                         nsIUTF8StringEnumerator** aResult)
+{
+  nsTArray<nsCString>* strings = new nsTArray<nsCString>;
+  if (!strings) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  nsresult rv = mParser.GetStrings(PromiseFlatCString(aSection).get(),
+                                   KeyCB, strings);
+  if (NS_SUCCEEDED(rv)) {
+    rv = NS_NewAdoptingUTF8StringEnumerator(aResult, strings);
+  }
+
+  if (NS_FAILED(rv)) {
+    delete strings;
+  }
+
+  return rv;
+
+}
+
+NS_IMETHODIMP
+nsINIParserImpl::GetString(const nsACString& aSection,
+                           const nsACString& aKey,
+                           nsACString& aResult)
+{
+  return mParser.GetString(PromiseFlatCString(aSection).get(),
+                           PromiseFlatCString(aKey).get(),
+                           aResult);
+}
diff --git a/xpcom/ds/nsINIParserImpl.h b/xpcom/ds/nsINIParserImpl.h
new file mode 100644
index 000000000..8e63f36d7
--- /dev/null
+++ b/xpcom/ds/nsINIParserImpl.h
@@ -0,0 +1,33 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsINIParserImpl_h__
+#define nsINIParserImpl_h__
+
+#include "nsIINIParser.h"
+#include "nsIFactory.h"
+#include "mozilla/Attributes.h"
+
+#define NS_INIPARSERFACTORY_CID \
+{ 0xdfac10a9, 0xdd24, 0x43cf, \
+  { 0xa0, 0x95, 0x6f, 0xfa, 0x2e, 0x4b, 0x6a, 0x6c } }
+
+#define NS_INIPARSERFACTORY_CONTRACTID \
+  "@mozilla.org/xpcom/ini-parser-factory;1"
+
+class nsINIParserFactory final
+  : public nsIINIParserFactory
+  , public nsIFactory
+{
+  ~nsINIParserFactory() {}
+
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIINIPARSERFACTORY
+  NS_DECL_NSIFACTORY
+};
+
+#endif // nsINIParserImpl_h__
diff --git a/xpcom/ds/nsINIProcessor.js b/xpcom/ds/nsINIProcessor.js
new file mode 100644
index 000000000..832f35a5f
--- /dev/null
+++ b/xpcom/ds/nsINIProcessor.js
@@ -0,0 +1,192 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+const Cr = Components.results;
+const Cu = Components.utils;
+
+Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
+
+function INIProcessorFactory() {
+}
+
+INIProcessorFactory.prototype = {
+    classID: Components.ID("{6ec5f479-8e13-4403-b6ca-fe4c2dca14fd}"),
+    QueryInterface : XPCOMUtils.generateQI([Ci.nsIINIParserFactory]),
+
+    createINIParser : function (aINIFile) {
+        return new INIProcessor(aINIFile);
+    }
+
+}; // end of INIProcessorFactory implementation
+
+const MODE_WRONLY = 0x02;
+const MODE_CREATE = 0x08;
+const MODE_TRUNCATE = 0x20;
+
+// nsIINIParser implementation
+function INIProcessor(aFile) {
+    this._iniFile = aFile;
+    this._iniData = {};
+    this._readFile();
+}
+
+INIProcessor.prototype = {
+    QueryInterface : XPCOMUtils.generateQI([Ci.nsIINIParser, Ci.nsIINIParserWriter]),
+
+    __utf8Converter : null, // UCS2 <--> UTF8 string conversion
+    get _utf8Converter() {
+        if (!this.__utf8Converter) {
+            this.__utf8Converter = Cc["@mozilla.org/intl/scriptableunicodeconverter"].
+                                  createInstance(Ci.nsIScriptableUnicodeConverter);
+            this.__utf8Converter.charset = "UTF-8";
+        }
+        return this.__utf8Converter;
+    },
+
+    __utf16leConverter : null, // UCS2 <--> UTF16LE string conversion
+    get _utf16leConverter() {
+        if (!this.__utf16leConverter) {
+            this.__utf16leConverter = Cc["@mozilla.org/intl/scriptableunicodeconverter"].
+                                  createInstance(Ci.nsIScriptableUnicodeConverter);
+            this.__utf16leConverter.charset = "UTF-16LE";
+        }
+        return this.__utf16leConverter;
+    },
+
+    _utfConverterReset : function() {
+        this.__utf8Converter = null;
+        this.__utf16leConverter = null;
+    },
+
+    _iniFile : null,
+    _iniData : null,
+
+    /*
+     * Reads the INI file and stores the data internally.
+     */
+    _readFile : function() {
+        // If file doesn't exist, there's nothing to do.
+        if (!this._iniFile.exists() || 0 == this._iniFile.fileSize)
+            return;
+
+        let iniParser = Cc["@mozilla.org/xpcom/ini-parser-factory;1"]
+            .getService(Ci.nsIINIParserFactory).createINIParser(this._iniFile);
+        for (let section of XPCOMUtils.IterStringEnumerator(iniParser.getSections())) {
+            this._iniData[section] = {};
+            for (let key of XPCOMUtils.IterStringEnumerator(iniParser.getKeys(section))) {
+                this._iniData[section][key] = iniParser.getString(section, key);
+            }
+        }
+    },
+
+    // nsIINIParser
+
+    getSections : function() {
+        let sections = [];
+        for (let section in this._iniData)
+            sections.push(section);
+        return new stringEnumerator(sections);
+    },
+
+    getKeys : function(aSection) {
+        let keys = [];
+        if (aSection in this._iniData)
+            for (let key in this._iniData[aSection])
+                keys.push(key);
+        return new stringEnumerator(keys);
+    },
+
+    getString : function(aSection, aKey) {
+        if (!(aSection in this._iniData))
+            throw Cr.NS_ERROR_FAILURE;
+        if (!(aKey in this._iniData[aSection]))
+            throw Cr.NS_ERROR_FAILURE;
+        return this._iniData[aSection][aKey];
+    },
+
+
+    // nsIINIParserWriter
+
+    setString : function(aSection, aKey, aValue) {
+        const isSectionIllegal = /[\0\r\n\[\]]/;
+        const isKeyValIllegal  = /[\0\r\n=]/;
+
+        if (isSectionIllegal.test(aSection))
+            throw Components.Exception("bad character in section name",
+                                       Cr.ERROR_ILLEGAL_VALUE);
+        if (isKeyValIllegal.test(aKey) || isKeyValIllegal.test(aValue))
+            throw Components.Exception("bad character in key/value",
+                                       Cr.ERROR_ILLEGAL_VALUE);
+
+        if (!(aSection in this._iniData))
+            this._iniData[aSection] = {};
+
+        this._iniData[aSection][aKey] = aValue;
+    },
+
+    writeFile : function(aFile, aFlags) {
+
+        let converter;
+        function writeLine(data) {
+            data += "\n";
+            data = converter.ConvertFromUnicode(data);
+            data += converter.Finish();
+            outputStream.write(data, data.length);
+        }
+
+        if (!aFile)
+            aFile = this._iniFile;
+
+        let safeStream = Cc["@mozilla.org/network/safe-file-output-stream;1"].
+                         createInstance(Ci.nsIFileOutputStream);
+        safeStream.init(aFile, MODE_WRONLY | MODE_CREATE | MODE_TRUNCATE,
+                        0o600, null);
+
+        var outputStream = Cc["@mozilla.org/network/buffered-output-stream;1"].
+                           createInstance(Ci.nsIBufferedOutputStream);
+        outputStream.init(safeStream, 8192);
+        outputStream.QueryInterface(Ci.nsISafeOutputStream); // for .finish()
+
+        if (Ci.nsIINIParserWriter.WRITE_UTF16 == aFlags
+         && 'nsIWindowsRegKey' in Ci) {
+            outputStream.write("\xFF\xFE", 2);
+            converter = this._utf16leConverter;
+        } else {
+            converter = this._utf8Converter;
+        }
+
+        for (let section in this._iniData) {
+            writeLine("[" + section + "]");
+            for (let key in this._iniData[section]) {
+                writeLine(key + "=" + this._iniData[section][key]);
+            }
+        }
+
+        outputStream.finish();
+    }
+};
+
+function stringEnumerator(stringArray) {
+    this._strings = stringArray;
+}
+stringEnumerator.prototype = {
+    QueryInterface : XPCOMUtils.generateQI([Ci.nsIUTF8StringEnumerator]),
+
+    _strings : null,
+    _enumIndex: 0,
+
+    hasMore : function() {
+        return (this._enumIndex < this._strings.length);
+    },
+
+    getNext : function() {
+        return this._strings[this._enumIndex++];
+    }
+};
+
+var component = [INIProcessorFactory];
+this.NSGetFactory = XPCOMUtils.generateNSGetFactory(component);
diff --git a/xpcom/ds/nsINIProcessor.manifest b/xpcom/ds/nsINIProcessor.manifest
new file mode 100644
index 000000000..da19d2aed
--- /dev/null
+++ b/xpcom/ds/nsINIProcessor.manifest
@@ -0,0 +1,2 @@
+component {6ec5f479-8e13-4403-b6ca-fe4c2dca14fd} nsINIProcessor.js
+contract @mozilla.org/xpcom/ini-processor-factory;1 {6ec5f479-8e13-4403-b6ca-fe4c2dca14fd}
diff --git a/xpcom/ds/nsIObserver.idl b/xpcom/ds/nsIObserver.idl
new file mode 100644
index 000000000..cfb4f912b
--- /dev/null
+++ b/xpcom/ds/nsIObserver.idl
@@ -0,0 +1,38 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * This interface is implemented by an object that wants
+ * to observe an event corresponding to a topic.
+ */
+
+[scriptable, function, uuid(DB242E01-E4D9-11d2-9DDE-000064657374)]
+interface nsIObserver : nsISupports {
+
+   /**
+    * Observe will be called when there is a notification for the
+    * topic |aTopic|.  This assumes that the object implementing
+    * this interface has been registered with an observer service
+    * such as the nsIObserverService. 
+    *
+    * If you expect multiple topics/subjects, the impl is 
+    * responsible for filtering.
+    *
+    * You should not modify, add, remove, or enumerate 
+    * notifications in the implemention of observe. 
+    *
+    * @param aSubject : Notification specific interface pointer.
+    * @param aTopic   : The notification topic or subject.
+    * @param aData    : Notification specific wide string.
+    *                    subject event.
+    */
+    void observe( in nsISupports aSubject,
+				  in string      aTopic,
+				  in wstring     aData );
+
+};
+
diff --git a/xpcom/ds/nsIObserverService.idl b/xpcom/ds/nsIObserverService.idl
new file mode 100644
index 000000000..d5b40e227
--- /dev/null
+++ b/xpcom/ds/nsIObserverService.idl
@@ -0,0 +1,77 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIObserver;
+interface nsISimpleEnumerator;
+
+/**
+ * nsIObserverService
+ * 
+ * Service allows a client listener (nsIObserver) to register and unregister for 
+ * notifications of specific string referenced topic. Service also provides a 
+ * way to notify registered listeners and a way to enumerate registered client 
+ * listeners.
+ */
+
+[scriptable, uuid(D07F5192-E3D1-11d2-8ACD-00105A1B8860)]
+interface nsIObserverService : nsISupports 
+{
+
+    /**
+     * AddObserver
+     *
+     * Registers a given listener for a notifications regarding the specified
+     * topic.
+     *
+     * @param anObserve : The interface pointer which will receive notifications.
+     * @param aTopic    : The notification topic or subject.
+     * @param ownsWeak  : If set to false, the nsIObserverService will hold a 
+     *                    strong reference to |anObserver|.  If set to true and 
+     *                    |anObserver| supports the nsIWeakReference interface,
+     *                    a weak reference will be held.  Otherwise an error will be
+     *                    returned.
+     */
+ 	void addObserver( in nsIObserver anObserver, in string aTopic, in boolean ownsWeak);
+
+    /**
+     * removeObserver
+     *
+     * Unregisters a given listener from notifications regarding the specified
+     * topic.
+     *
+     * @param anObserver : The interface pointer which will stop recieving
+     *                     notifications.
+     * @param aTopic     : The notification topic or subject.
+     */
+    void removeObserver( in nsIObserver anObserver, in string aTopic );
+
+    /**
+     * notifyObservers
+     *
+     * Notifies all registered listeners of the given topic.
+     *
+     * @param aSubject : Notification specific interface pointer.
+     * @param aTopic   : The notification topic or subject.
+     * @param someData : Notification specific wide string.
+     */
+    void notifyObservers( in nsISupports aSubject, 
+                          in string aTopic, 
+                          in wstring someData );
+
+    /**
+     * enumerateObservers
+     *
+     * Returns an enumeration of all registered listeners.
+     *
+     * @param aTopic   : The notification topic or subject.
+     */
+	nsISimpleEnumerator enumerateObservers( in string aTopic );
+
+
+};
+
+
diff --git a/xpcom/ds/nsIPersistentProperties.h b/xpcom/ds/nsIPersistentProperties.h
new file mode 100644
index 000000000..e886076e9
--- /dev/null
+++ b/xpcom/ds/nsIPersistentProperties.h
@@ -0,0 +1,14 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+#ifndef __gen_nsIPersistentProperties_h__
+#define __gen_nsIPersistentProperties_h__
+
+// "soft" switch over to an IDL generated header file
+#include "nsIPersistentProperties2.h"
+
+#endif /* __gen_nsIPersistentProperties_h__ */
diff --git a/xpcom/ds/nsIPersistentProperties2.idl b/xpcom/ds/nsIPersistentProperties2.idl
new file mode 100644
index 000000000..3f24bb773
--- /dev/null
+++ b/xpcom/ds/nsIPersistentProperties2.idl
@@ -0,0 +1,63 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIProperties.idl"
+
+interface nsIInputStream;
+interface nsIOutputStream;
+interface nsISimpleEnumerator;
+
+[scriptable, uuid(283EE646-1AEF-11D4-98B3-00C04fA0CE9A)]
+interface nsIPropertyElement : nsISupports {
+  attribute AUTF8String key;
+  attribute AString value;
+};
+
+[scriptable, uuid(706867af-0400-4faa-beb1-0dae87308784)]
+interface nsIPersistentProperties : nsIProperties
+{
+  /**
+   * load a set of name/value pairs from the input stream
+   * names and values should be in UTF8
+   */
+  void load(in nsIInputStream input);
+
+  /**
+   * output the values to the stream - results will be in UTF8
+   */
+  void save(in nsIOutputStream output, in AUTF8String header);
+
+  /**
+   * get an enumeration of nsIPropertyElement objects,
+   * which are read-only (i.e. setting properties on the element will
+   * not make changes back into the source nsIPersistentProperties
+   */
+  nsISimpleEnumerator enumerate();
+
+  /**
+   * shortcut to nsIProperty's get() which retrieves a string value
+   * directly (and thus faster)
+   */
+  AString getStringProperty(in AUTF8String key);
+
+  /**
+   * shortcut to nsIProperty's set() which sets a string value
+   * directly (and thus faster). If the given property already exists,
+   * then the old value will be returned
+   */
+  AString setStringProperty(in AUTF8String key, in AString value);
+};
+
+
+%{C++
+
+#define NS_IPERSISTENTPROPERTIES_CID \
+{ 0x2245e573, 0x9464, 0x11d2, \
+  { 0x9b, 0x8b, 0x0, 0x80, 0x5f, 0x8a, 0x16, 0xd9 } }
+
+#define NS_PERSISTENTPROPERTIES_CONTRACTID "@mozilla.org/persistent-properties;1"
+
+%}
+
diff --git a/xpcom/ds/nsIProperties.idl b/xpcom/ds/nsIProperties.idl
new file mode 100644
index 000000000..a87e14443
--- /dev/null
+++ b/xpcom/ds/nsIProperties.idl
@@ -0,0 +1,46 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/*
+ * Simple mapping service interface.
+ */
+
+[scriptable, uuid(78650582-4e93-4b60-8e85-26ebd3eb14ca)]
+interface nsIProperties : nsISupports
+{
+    /**
+     * Gets a property with a given name. 
+     *
+     * @throws NS_ERROR_FAILURE if a property with that name doesn't exist.
+     * @throws NS_ERROR_NO_INTERFACE if the found property fails to QI to the 
+     * given iid.
+     */
+    void get(in string prop, in nsIIDRef iid, 
+             [iid_is(iid),retval] out nsQIResult result);
+
+    /**
+     * Sets a property with a given name to a given value. 
+     */
+    void set(in string prop, in nsISupports value);
+
+    /**
+     * Returns true if the property with the given name exists.
+     */
+    boolean has(in string prop);
+
+    /**
+     * Undefines a property.
+     * @throws NS_ERROR_FAILURE if a property with that name doesn't
+     * already exist.
+     */
+    void undefine(in string prop);
+
+    /**
+     *  Returns an array of the keys.
+     */
+    void getKeys(out uint32_t count, [array, size_is(count), retval] out string keys);
+};
diff --git a/xpcom/ds/nsIProperty.idl b/xpcom/ds/nsIProperty.idl
new file mode 100644
index 000000000..9e6e1e487
--- /dev/null
+++ b/xpcom/ds/nsIProperty.idl
@@ -0,0 +1,25 @@
+/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* nsIVariant based Property support. */
+
+#include "nsISupports.idl"
+
+interface nsIVariant;
+
+[scriptable, uuid(6dcf9030-a49f-11d5-910d-0010a4e73d9a)]
+interface nsIProperty : nsISupports
+{
+    /**
+     * Get the name of the property.
+     */
+    readonly attribute AString    name;
+
+    /**
+     * Get the value of the property.
+     */
+    readonly attribute nsIVariant value;
+};
diff --git a/xpcom/ds/nsIPropertyBag.idl b/xpcom/ds/nsIPropertyBag.idl
new file mode 100644
index 000000000..1d1dfced7
--- /dev/null
+++ b/xpcom/ds/nsIPropertyBag.idl
@@ -0,0 +1,30 @@
+/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* nsIVariant based Property Bag support. */
+
+#include "nsISupports.idl"
+
+interface nsIVariant;
+interface nsISimpleEnumerator;
+
+[scriptable, uuid(bfcd37b0-a49f-11d5-910d-0010a4e73d9a)]
+interface nsIPropertyBag : nsISupports
+{
+    /**
+     * Get a nsISimpleEnumerator whose elements are nsIProperty objects.
+     */
+    readonly attribute nsISimpleEnumerator enumerator;
+
+    /**
+     * Get a property value for the given name.
+     * @throws NS_ERROR_FAILURE if a property with that name doesn't
+     * exist.
+     */
+    nsIVariant getProperty(in AString name);
+};
+
+
diff --git a/xpcom/ds/nsIPropertyBag2.idl b/xpcom/ds/nsIPropertyBag2.idl
new file mode 100644
index 000000000..7b4be7f4a
--- /dev/null
+++ b/xpcom/ds/nsIPropertyBag2.idl
@@ -0,0 +1,42 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* nsIVariant based Property Bag support. */
+
+#include "nsIPropertyBag.idl"
+
+[scriptable, uuid(625cfd1e-da1e-4417-9ee9-dbc8e0b3fd79)]
+interface nsIPropertyBag2 : nsIPropertyBag
+{
+  // Accessing a property as a different type may attempt conversion to the
+  // requested value
+
+  int32_t     getPropertyAsInt32       (in AString prop);
+  uint32_t    getPropertyAsUint32      (in AString prop);
+  int64_t     getPropertyAsInt64       (in AString prop);
+  uint64_t    getPropertyAsUint64      (in AString prop);
+  double      getPropertyAsDouble      (in AString prop);
+  AString     getPropertyAsAString     (in AString prop);
+  ACString    getPropertyAsACString    (in AString prop);
+  AUTF8String getPropertyAsAUTF8String (in AString prop);
+  boolean     getPropertyAsBool        (in AString prop);
+
+  /**
+   * This method returns null if the value exists, but is null.
+   */
+  void        getPropertyAsInterface   (in AString prop,
+                                        in nsIIDRef iid,
+                                        [iid_is(iid), retval] out nsQIResult result);
+
+  /**
+   * This method returns null if the value does not exist,
+   * or exists but is null.
+   */
+  nsIVariant  get                      (in AString prop);
+ 
+  /**
+   * Check for the existence of a key.
+   */
+  boolean     hasKey                   (in AString prop);
+};
diff --git a/xpcom/ds/nsISerializable.idl b/xpcom/ds/nsISerializable.idl
new file mode 100644
index 000000000..f525f3a8f
--- /dev/null
+++ b/xpcom/ds/nsISerializable.idl
@@ -0,0 +1,32 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIObjectInputStream;
+interface nsIObjectOutputStream;
+
+[scriptable, uuid(91cca981-c26d-44a8-bebe-d9ed4891503a)]
+interface nsISerializable : nsISupports
+{
+    /**
+     * Initialize the object implementing nsISerializable, which must have
+     * been freshly constructed via CreateInstance.  All data members that
+     * can't be set to default values must have been serialized by write,
+     * and should be read from aInputStream in the same order by this method.
+     */
+    void read(in nsIObjectInputStream aInputStream);
+
+    /**
+     * Serialize the object implementing nsISerializable to aOutputStream, by
+     * writing each data member that must be recovered later to reconstitute
+     * a working replica of this object, in a canonical member and byte order,
+     * to aOutputStream.
+     *
+     * NB: a class that implements nsISerializable *must* also implement
+     * nsIClassInfo, in particular nsIClassInfo::GetClassID.
+     */
+    void write(in nsIObjectOutputStream aOutputStream);
+};
diff --git a/xpcom/ds/nsISimpleEnumerator.idl b/xpcom/ds/nsISimpleEnumerator.idl
new file mode 100644
index 000000000..cbb0cd200
--- /dev/null
+++ b/xpcom/ds/nsISimpleEnumerator.idl
@@ -0,0 +1,46 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * Used to enumerate over elements defined by its implementor.
+ * Although hasMoreElements() can be called independently of getNext(),
+ * getNext() must be pre-ceeded by a call to hasMoreElements(). There is
+ * no way to "reset" an enumerator, once you obtain one.
+ *
+ * @version 1.0
+ */
+
+[scriptable, uuid(D1899240-F9D2-11D2-BDD6-000064657374)]
+interface nsISimpleEnumerator : nsISupports {
+  /**
+   * Called to determine whether or not the enumerator has
+   * any elements that can be returned via getNext(). This method
+   * is generally used to determine whether or not to initiate or
+   * continue iteration over the enumerator, though it can be
+   * called without subsequent getNext() calls. Does not affect
+   * internal state of enumerator.
+   *
+   * @see getNext()
+   * @return true if there are remaining elements in the enumerator.
+   *         false if there are no more elements in the enumerator.
+   */                                            
+  boolean hasMoreElements();
+
+  /**
+   * Called to retrieve the next element in the enumerator. The "next"
+   * element is the first element upon the first call. Must be
+   * pre-ceeded by a call to hasMoreElements() which returns PR_TRUE.
+   * This method is generally called within a loop to iterate over
+   * the elements in the enumerator.
+   *
+   * @see hasMoreElements()
+   * @throws NS_ERROR_FAILURE if there are no more elements
+   *                          to enumerate.
+   * @return the next element in the enumeration.
+   */
+  nsISupports getNext();
+};
diff --git a/xpcom/ds/nsIStringEnumerator.idl b/xpcom/ds/nsIStringEnumerator.idl
new file mode 100644
index 000000000..d9c4130ee
--- /dev/null
+++ b/xpcom/ds/nsIStringEnumerator.idl
@@ -0,0 +1,25 @@
+/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * Used to enumerate over an ordered list of strings.
+ */
+
+[scriptable, uuid(50d3ef6c-9380-4f06-9fb2-95488f7d141c)]
+interface nsIStringEnumerator : nsISupports
+{
+    boolean hasMore();
+    AString getNext();
+};
+
+[scriptable, uuid(9bdf1010-3695-4907-95ed-83d0410ec307)]
+interface nsIUTF8StringEnumerator : nsISupports
+{
+    boolean hasMore();
+    AUTF8String getNext();
+};
+
diff --git a/xpcom/ds/nsISupportsArray.idl b/xpcom/ds/nsISupportsArray.idl
new file mode 100644
index 000000000..30e2a5035
--- /dev/null
+++ b/xpcom/ds/nsISupportsArray.idl
@@ -0,0 +1,60 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+#include "nsICollection.idl"
+
+/*
+ * This entire interface is deprecated and should not be used.
+ * See nsIArray and nsIMutableArray for the new implementations.
+ *
+ * http://groups.google.com/groups?q=nsisupportsarray+group:netscape.public.mozilla.xpcom&hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=3D779491.3050506%40netscape.com&rnum=2
+ * http://groups.google.com/groups?q=nsisupportsarray+group:netscape.public.mozilla.xpcom&hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=al8412%245ab2%40ripley.netscape.com&rnum=8
+ */
+
+%{C++
+
+class nsIBidirectionalEnumerator;
+class nsISupportsArray;
+ 
+#define NS_SUPPORTSARRAY_CID                         \
+{ /* bda17d50-0d6b-11d3-9331-00104ba0fd40 */         \
+    0xbda17d50,                                      \
+    0x0d6b,                                          \
+    0x11d3,                                          \
+    {0x93, 0x31, 0x00, 0x10, 0x4b, 0xa0, 0xfd, 0x40} \
+}
+#define NS_SUPPORTSARRAY_CONTRACTID "@mozilla.org/supports-array;1"
+ 
+%}
+
+[deprecated, scriptable, uuid(241addc8-3608-4e73-8083-2fd6fa09eba2)]
+interface nsISupportsArray : nsICollection {
+
+  [notxpcom] long IndexOf([const] in nsISupports aPossibleElement);
+  
+  // xpcom-compatible versions
+  long GetIndexOf(in nsISupports aPossibleElement);
+  
+  [notxpcom] boolean InsertElementAt(in nsISupports aElement,
+                                     in unsigned long aIndex);
+  [notxpcom] boolean ReplaceElementAt(in nsISupports aElement,
+                                      in unsigned long aIndex);
+
+  [notxpcom] boolean RemoveElementAt(in unsigned long aIndex);
+  
+  // xpcom-compatible versions
+  void DeleteElementAt(in unsigned long aIndex);
+  
+  nsISupportsArray clone();
+};
+
+%{C++
+
+// Construct and return a default implementation of nsISupportsArray:
+extern MOZ_MUST_USE nsresult
+NS_NewISupportsArray(nsISupportsArray** aInstancePtrResult);
+
+%}
diff --git a/xpcom/ds/nsISupportsIterators.idl b/xpcom/ds/nsISupportsIterators.idl
new file mode 100644
index 000000000..8d47375d5
--- /dev/null
+++ b/xpcom/ds/nsISupportsIterators.idl
@@ -0,0 +1,292 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* nsISupportsIterators.idl --- IDL defining general purpose iterators */
+
+
+#include "nsISupports.idl"
+
+
+  /*
+    ...
+  */
+
+
+  /**
+   * ...
+   */
+[scriptable, uuid(7330650e-1dd2-11b2-a0c2-9ff86ee97bed)]
+interface nsIOutputIterator : nsISupports
+  {
+      /**
+       * Put |anElementToPut| into the underlying container or sequence at the position currently pointed to by this iterator.
+       * The iterator and the underlying container or sequence cooperate to |Release()|
+       * the replaced element, if any and if necessary, and to |AddRef()| the new element.
+       *
+       * The result is undefined if this iterator currently points outside the
+       * useful range of the underlying container or sequence.
+       *
+       * @param anElementToPut the element to place into the underlying container or sequence
+       */
+    void putElement( in nsISupports anElementToPut );
+
+      /**
+       * Advance this iterator to the next position in the underlying container or sequence.
+       */
+    void stepForward();
+  };
+
+  /**
+   * ...
+   */
+[scriptable, uuid(85585e12-1dd2-11b2-a930-f6929058269a)]
+interface nsIInputIterator : nsISupports
+  {
+      /**
+       * Retrieve (and |AddRef()|) the element this iterator currently points to.
+       *
+       * The result is undefined if this iterator currently points outside the
+       * useful range of the underlying container or sequence.
+       *
+       * @result a new reference to the element this iterator currently points to (if any)
+       */
+    nsISupports getElement();
+
+      /**
+       * Advance this iterator to the next position in the underlying container or sequence.
+       */
+    void stepForward();
+
+      /**
+       * Test if |anotherIterator| points to the same position in the underlying container or sequence.
+       *
+       * The result is undefined if |anotherIterator| was not created by or for the same underlying container or sequence.
+       *
+       * @param anotherIterator another iterator to compare against, created by or for the same underlying container or sequence
+       * @result true if |anotherIterator| points to the same position in the underlying container or sequence
+       */
+    boolean isEqualTo( in nsISupports anotherIterator );
+
+      /**
+       * Create a new iterator pointing to the same position in the underlying container or sequence to which this iterator currently points.
+       * The returned iterator is suitable for use in a subsequent call to |isEqualTo()| against this iterator.
+       *
+       * @result a new iterator pointing at the same position in the same underlying container or sequence as this iterator
+       */
+    nsISupports clone();
+  };
+
+  /**
+   * ...
+   */
+[scriptable, uuid(8da01646-1dd2-11b2-98a7-c7009045be7e)]
+interface nsIForwardIterator : nsISupports
+  {
+      /**
+       * Retrieve (and |AddRef()|) the element this iterator currently points to.
+       *
+       * The result is undefined if this iterator currently points outside the
+       * useful range of the underlying container or sequence.
+       *
+       * @result a new reference to the element this iterator currently points to (if any)
+       */
+    nsISupports getElement();
+
+      /**
+       * Put |anElementToPut| into the underlying container or sequence at the position currently pointed to by this iterator.
+       * The iterator and the underlying container or sequence cooperate to |Release()|
+       * the replaced element, if any and if necessary, and to |AddRef()| the new element.
+       *
+       * The result is undefined if this iterator currently points outside the
+       * useful range of the underlying container or sequence.
+       *
+       * @param anElementToPut the element to place into the underlying container or sequence
+       */
+    void putElement( in nsISupports anElementToPut );
+
+      /**
+       * Advance this iterator to the next position in the underlying container or sequence.
+       */
+    void stepForward();
+
+      /**
+       * Test if |anotherIterator| points to the same position in the underlying container or sequence.
+       *
+       * The result is undefined if |anotherIterator| was not created by or for the same underlying container or sequence.
+       *
+       * @param anotherIterator another iterator to compare against, created by or for the same underlying container or sequence
+       * @result true if |anotherIterator| points to the same position in the underlying container or sequence
+       */
+    boolean isEqualTo( in nsISupports anotherIterator );
+
+      /**
+       * Create a new iterator pointing to the same position in the underlying container or sequence to which this iterator currently points.
+       * The returned iterator is suitable for use in a subsequent call to |isEqualTo()| against this iterator.
+       *
+       * @result a new iterator pointing at the same position in the same underlying container or sequence as this iterator
+       */
+    nsISupports clone();
+  };
+
+  /**
+   * ...
+   */
+[scriptable, uuid(948defaa-1dd1-11b2-89f6-8ce81f5ebda9)]
+interface nsIBidirectionalIterator : nsISupports
+  {
+      /**
+       * Retrieve (and |AddRef()|) the element this iterator currently points to.
+       *
+       * The result is undefined if this iterator currently points outside the
+       * useful range of the underlying container or sequence.
+       *
+       * @result a new reference to the element this iterator currently points to (if any)
+       */
+    nsISupports getElement();
+
+      /**
+       * Put |anElementToPut| into the underlying container or sequence at the position currently pointed to by this iterator.
+       * The iterator and the underlying container or sequence cooperate to |Release()|
+       * the replaced element, if any and if necessary, and to |AddRef()| the new element.
+       *
+       * The result is undefined if this iterator currently points outside the
+       * useful range of the underlying container or sequence.
+       *
+       * @param anElementToPut the element to place into the underlying container or sequence
+       */
+    void putElement( in nsISupports anElementToPut );
+
+      /**
+       * Advance this iterator to the next position in the underlying container or sequence.
+       */
+    void stepForward();
+
+      /**
+       * Move this iterator to the previous position in the underlying container or sequence.
+       */
+    void stepBackward();
+
+      /**
+       * Test if |anotherIterator| points to the same position in the underlying container or sequence.
+       *
+       * The result is undefined if |anotherIterator| was not created by or for the same underlying container or sequence.
+       *
+       * @param anotherIterator another iterator to compare against, created by or for the same underlying container or sequence
+       * @result true if |anotherIterator| points to the same position in the underlying container or sequence
+       */
+    boolean isEqualTo( in nsISupports anotherIterator );
+
+      /**
+       * Create a new iterator pointing to the same position in the underlying container or sequence to which this iterator currently points.
+       * The returned iterator is suitable for use in a subsequent call to |isEqualTo()| against this iterator.
+       *
+       * @result a new iterator pointing at the same position in the same underlying container or sequence as this iterator
+       */
+    nsISupports clone();
+  };
+
+  /**
+   * ...
+   */
+[scriptable, uuid(9bd6fdb0-1dd1-11b2-9101-d15375968230)]
+interface nsIRandomAccessIterator : nsISupports
+  {
+      /**
+       * Retrieve (and |AddRef()|) the element this iterator currently points to.
+       *
+       * The result is undefined if this iterator currently points outside the
+       * useful range of the underlying container or sequence.
+       *
+       * @result a new reference to the element this iterator currently points to (if any)
+       */
+    nsISupports getElement();
+
+      /**
+       * Retrieve (and |AddRef()|) an element at some offset from where this iterator currently points.
+       * The offset may be negative.  |getElementAt(0)| is equivalent to |getElement()|.
+       *
+       * The result is undefined if this iterator currently points outside the
+       * useful range of the underlying container or sequence.
+       *
+       * @param anOffset a |0|-based offset from the position to which this iterator currently points
+       * @result a new reference to the indicated element (if any)
+       */
+    nsISupports getElementAt( in int32_t anOffset );
+
+      /**
+       * Put |anElementToPut| into the underlying container or sequence at the position currently pointed to by this iterator.
+       * The iterator and the underlying container or sequence cooperate to |Release()|
+       * the replaced element, if any and if necessary, and to |AddRef()| the new element.
+       *
+       * The result is undefined if this iterator currently points outside the
+       * useful range of the underlying container or sequence.
+       *
+       * @param anElementToPut the element to place into the underlying container or sequence
+       */
+    void putElement( in nsISupports anElementToPut );
+
+      /**
+       * Put |anElementToPut| into the underlying container or sequence at the position |anOffset| away from that currently pointed to by this iterator.
+       * The iterator and the underlying container or sequence cooperate to |Release()|
+       * the replaced element, if any and if necessary, and to |AddRef()| the new element.
+       * |putElementAt(0, obj)| is equivalent to |putElement(obj)|.
+       *
+       * The result is undefined if this iterator currently points outside the
+       * useful range of the underlying container or sequence.
+       *
+       * @param anOffset a |0|-based offset from the position to which this iterator currently points
+       * @param anElementToPut the element to place into the underlying container or sequence
+       */
+    void putElementAt( in int32_t anOffset, in nsISupports anElementToPut );
+
+      /**
+       * Advance this iterator to the next position in the underlying container or sequence.
+       */
+    void stepForward();
+
+      /**
+       * Move this iterator by |anOffset| positions in the underlying container or sequence.
+       * |anOffset| may be negative.  |stepForwardBy(1)| is equivalent to |stepForward()|.
+       * |stepForwardBy(0)| is a no-op.
+       *
+       * @param anOffset a |0|-based offset from the position to which this iterator currently points
+       */
+    void stepForwardBy( in int32_t anOffset );
+
+      /**
+       * Move this iterator to the previous position in the underlying container or sequence.
+       */
+    void stepBackward();
+
+      /**
+       * Move this iterator backwards by |anOffset| positions in the underlying container or sequence.
+       * |anOffset| may be negative.  |stepBackwardBy(1)| is equivalent to |stepBackward()|.
+       * |stepBackwardBy(n)| is equivalent to |stepForwardBy(-n)|.  |stepBackwardBy(0)| is a no-op.
+       *
+       * @param anOffset a |0|-based offset from the position to which this iterator currently points
+       */
+    void stepBackwardBy( in int32_t anOffset );
+
+      /**
+       * Test if |anotherIterator| points to the same position in the underlying container or sequence.
+       *
+       * The result is undefined if |anotherIterator| was not created by or for the same underlying container or sequence.
+       *
+       * @param anotherIterator another iterator to compare against, created by or for the same underlying container or sequence
+       * @result true if |anotherIterator| points to the same position in the underlying container or sequence
+       */
+    boolean isEqualTo( in nsISupports anotherIterator );
+
+      /**
+       * Create a new iterator pointing to the same position in the underlying container or sequence to which this iterator currently points.
+       * The returned iterator is suitable for use in a subsequent call to |isEqualTo()| against this iterator.
+       *
+       * @result a new iterator pointing at the same position in the same underlying container or sequence as this iterator
+       */
+    nsISupports clone();
+  };
+
+%{C++
+%}
diff --git a/xpcom/ds/nsISupportsPrimitives.idl b/xpcom/ds/nsISupportsPrimitives.idl
new file mode 100644
index 000000000..71940739c
--- /dev/null
+++ b/xpcom/ds/nsISupportsPrimitives.idl
@@ -0,0 +1,235 @@
+/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* nsISupports wrappers for single primitive pieces of data. */
+
+#include "nsISupports.idl"
+
+/**
+ * Primitive base interface.
+ *
+ * These first three are pointer types and do data copying
+ * using the nsIMemory. Be careful!
+ */
+
+[scriptable, uuid(d0d4b136-1dd1-11b2-9371-f0727ef827c0)]
+interface nsISupportsPrimitive : nsISupports
+{
+    const unsigned short TYPE_ID                = 1;
+    const unsigned short TYPE_CSTRING           = 2;
+    const unsigned short TYPE_STRING            = 3;
+    const unsigned short TYPE_PRBOOL            = 4;
+    const unsigned short TYPE_PRUINT8           = 5;
+    const unsigned short TYPE_PRUINT16          = 6;
+    const unsigned short TYPE_PRUINT32          = 7;
+    const unsigned short TYPE_PRUINT64          = 8;
+    const unsigned short TYPE_PRTIME            = 9;
+    const unsigned short TYPE_CHAR              = 10;
+    const unsigned short TYPE_PRINT16           = 11;
+    const unsigned short TYPE_PRINT32           = 12;
+    const unsigned short TYPE_PRINT64           = 13;
+    const unsigned short TYPE_FLOAT             = 14;
+    const unsigned short TYPE_DOUBLE            = 15;
+    const unsigned short TYPE_VOID              = 16;
+    const unsigned short TYPE_INTERFACE_POINTER = 17;
+
+    readonly attribute unsigned short type;
+};
+
+/**
+ * Scriptable storage for nsID structures
+ */
+
+[scriptable, uuid(d18290a0-4a1c-11d3-9890-006008962422)]
+interface nsISupportsID : nsISupportsPrimitive
+{
+    attribute nsIDPtr data;
+    string toString();
+};
+
+/**
+ * Scriptable storage for ASCII strings
+ */
+
+[scriptable, uuid(d65ff270-4a1c-11d3-9890-006008962422)]
+interface nsISupportsCString : nsISupportsPrimitive
+{
+    attribute ACString data;
+    string toString();
+};
+
+/**
+ * Scriptable storage for Unicode strings
+ */
+
+[scriptable, uuid(d79dc970-4a1c-11d3-9890-006008962422)]
+interface nsISupportsString : nsISupportsPrimitive
+{
+    attribute AString data;
+    wstring toString();
+};
+
+/**
+ * The rest are truly primitive and are passed by value
+ */ 
+
+/**
+ * Scriptable storage for booleans
+ */
+
+[scriptable, uuid(ddc3b490-4a1c-11d3-9890-006008962422)]
+interface nsISupportsPRBool : nsISupportsPrimitive
+{
+    attribute boolean data;
+    string toString();
+};
+
+/**
+ * Scriptable storage for 8-bit integers
+ */
+
+[scriptable, uuid(dec2e4e0-4a1c-11d3-9890-006008962422)]
+interface nsISupportsPRUint8 : nsISupportsPrimitive
+{
+    attribute uint8_t data;
+    string toString();
+};
+
+/**
+ * Scriptable storage for unsigned 16-bit integers
+ */
+
+[scriptable, uuid(dfacb090-4a1c-11d3-9890-006008962422)]
+interface nsISupportsPRUint16 : nsISupportsPrimitive
+{
+    attribute uint16_t data;
+    string toString();
+};
+
+/**
+ * Scriptable storage for unsigned 32-bit integers
+ */
+
+[scriptable, uuid(e01dc470-4a1c-11d3-9890-006008962422)]
+interface nsISupportsPRUint32 : nsISupportsPrimitive
+{
+    attribute uint32_t data;
+    string toString();
+};
+
+/**
+ * Scriptable storage for 64-bit integers
+ */
+
+[scriptable, uuid(e13567c0-4a1c-11d3-9890-006008962422)]
+interface nsISupportsPRUint64 : nsISupportsPrimitive
+{
+    attribute uint64_t data;
+    string toString();
+};
+
+/**
+ * Scriptable storage for NSPR date/time values
+ */
+
+[scriptable, uuid(e2563630-4a1c-11d3-9890-006008962422)]
+interface nsISupportsPRTime : nsISupportsPrimitive
+{
+    attribute PRTime data;
+    string toString();
+};
+
+/**
+ * Scriptable storage for single character values
+ * (often used to store an ASCII character)
+ */
+
+[scriptable, uuid(e2b05e40-4a1c-11d3-9890-006008962422)]
+interface nsISupportsChar : nsISupportsPrimitive
+{
+    attribute char data;
+    string toString();
+};
+
+/**
+ * Scriptable storage for 16-bit integers
+ */
+
+[scriptable, uuid(e30d94b0-4a1c-11d3-9890-006008962422)]
+interface nsISupportsPRInt16 : nsISupportsPrimitive
+{
+    attribute int16_t data;
+    string toString();
+};
+
+/**
+ * Scriptable storage for 32-bit integers
+ */
+
+[scriptable, uuid(e36c5250-4a1c-11d3-9890-006008962422)]
+interface nsISupportsPRInt32 : nsISupportsPrimitive
+{
+    attribute int32_t data;
+    string toString();
+};
+
+/**
+ * Scriptable storage for 64-bit integers
+ */
+
+[scriptable, uuid(e3cb0ff0-4a1c-11d3-9890-006008962422)]
+interface nsISupportsPRInt64 : nsISupportsPrimitive
+{
+    attribute int64_t data;
+    string toString();
+};
+
+/**
+ * Scriptable storage for floating point numbers
+ */
+
+[scriptable, uuid(abeaa390-4ac0-11d3-baea-00805f8a5dd7)]
+interface nsISupportsFloat : nsISupportsPrimitive
+{
+    attribute float data;
+    string toString();
+};
+
+/**
+ * Scriptable storage for doubles
+ */
+
+[scriptable, uuid(b32523a0-4ac0-11d3-baea-00805f8a5dd7)]
+interface nsISupportsDouble : nsISupportsPrimitive
+{
+    attribute double data;
+    string toString();
+};
+
+/**
+ * Scriptable storage for generic pointers
+ */
+
+[scriptable, uuid(464484f0-568d-11d3-baf8-00805f8a5dd7)]
+interface nsISupportsVoid : nsISupportsPrimitive
+{
+    [noscript] attribute voidPtr data;
+    string toString();
+};
+
+/**
+ * Scriptable storage for other XPCOM objects
+ */
+
+[scriptable, uuid(995ea724-1dd1-11b2-9211-c21bdd3e7ed0)]
+interface nsISupportsInterfacePointer : nsISupportsPrimitive
+{
+    attribute nsISupports data;
+    attribute nsIDPtr dataIID;
+
+    string toString();
+};
+
+
diff --git a/xpcom/ds/nsIVariant.idl b/xpcom/ds/nsIVariant.idl
new file mode 100644
index 000000000..ef5528463
--- /dev/null
+++ b/xpcom/ds/nsIVariant.idl
@@ -0,0 +1,155 @@
+/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* The long avoided variant support for xpcom. */
+
+#include "nsISupports.idl"
+
+[scriptable,uuid(4d12e540-83d7-11d5-90ed-0010a4e73d9a)]
+interface nsIDataType : nsISupports
+{
+    // These MUST match the declarations in xpt_struct.h. 
+    // Otherwise the world is likely to explode.   
+                                                   // From xpt_struct.h ...
+    const uint16_t VTYPE_INT8                =  0; // TD_INT8              = 0,
+    const uint16_t VTYPE_INT16               =  1; // TD_INT16             = 1,
+    const uint16_t VTYPE_INT32               =  2; // TD_INT32             = 2,
+    const uint16_t VTYPE_INT64               =  3; // TD_INT64             = 3,
+    const uint16_t VTYPE_UINT8               =  4; // TD_UINT8             = 4,
+    const uint16_t VTYPE_UINT16              =  5; // TD_UINT16            = 5,
+    const uint16_t VTYPE_UINT32              =  6; // TD_UINT32            = 6,
+    const uint16_t VTYPE_UINT64              =  7; // TD_UINT64            = 7,
+    const uint16_t VTYPE_FLOAT               =  8; // TD_FLOAT             = 8, 
+    const uint16_t VTYPE_DOUBLE              =  9; // TD_DOUBLE            = 9,
+    const uint16_t VTYPE_BOOL                = 10; // TD_BOOL              = 10,
+    const uint16_t VTYPE_CHAR                = 11; // TD_CHAR              = 11,
+    const uint16_t VTYPE_WCHAR               = 12; // TD_WCHAR             = 12,
+    const uint16_t VTYPE_VOID                = 13; // TD_VOID              = 13,
+    const uint16_t VTYPE_ID                  = 14; // TD_PNSIID            = 14,
+    const uint16_t VTYPE_DOMSTRING           = 15; // TD_DOMSTRING         = 15,
+    const uint16_t VTYPE_CHAR_STR            = 16; // TD_PSTRING           = 16,
+    const uint16_t VTYPE_WCHAR_STR           = 17; // TD_PWSTRING          = 17,
+    const uint16_t VTYPE_INTERFACE           = 18; // TD_INTERFACE_TYPE    = 18,
+    const uint16_t VTYPE_INTERFACE_IS        = 19; // TD_INTERFACE_IS_TYPE = 19,
+    const uint16_t VTYPE_ARRAY               = 20; // TD_ARRAY             = 20,
+    const uint16_t VTYPE_STRING_SIZE_IS      = 21; // TD_PSTRING_SIZE_IS   = 21,
+    const uint16_t VTYPE_WSTRING_SIZE_IS     = 22; // TD_PWSTRING_SIZE_IS  = 22,
+    const uint16_t VTYPE_UTF8STRING          = 23; // TD_UTF8STRING        = 23,
+    const uint16_t VTYPE_CSTRING             = 24; // TD_CSTRING           = 24,
+    const uint16_t VTYPE_ASTRING             = 25; // TD_ASTRING           = 25,
+    const uint16_t VTYPE_EMPTY_ARRAY         = 254;
+    const uint16_t VTYPE_EMPTY               = 255;
+};
+
+/**
+ * XPConnect has magic to transparently convert between nsIVariant and JS types.
+ * We mark the interface [scriptable] so that JS can use methods
+ * that refer to this interface. But we mark all the methods and attributes
+ * [noscript] since any nsIVariant object will be automatically converted to a
+ * JS type anyway.
+ */
+
+[scriptable, uuid(81e4c2de-acac-4ad6-901a-b5fb1b851a0d)]
+interface nsIVariant : nsISupports
+{
+    [noscript] readonly attribute uint16_t     dataType;
+
+    [noscript] uint8_t      getAsInt8();
+    [noscript] int16_t      getAsInt16();
+    [noscript] int32_t      getAsInt32();
+    [noscript] int64_t      getAsInt64();
+    [noscript] uint8_t      getAsUint8();
+    [noscript] uint16_t     getAsUint16();
+    [noscript] uint32_t     getAsUint32();
+    [noscript] uint64_t     getAsUint64();
+    [noscript] float        getAsFloat();
+    [noscript] double       getAsDouble();
+    [noscript] boolean      getAsBool();
+    [noscript] char         getAsChar();
+    [noscript] wchar        getAsWChar();
+    [notxpcom] nsresult     getAsID(out nsID retval);
+    [noscript] AString      getAsAString();
+    [noscript] DOMString    getAsDOMString();
+    [noscript] ACString     getAsACString();
+    [noscript] AUTF8String  getAsAUTF8String();
+    [noscript] string       getAsString();
+    [noscript] wstring      getAsWString();
+    [noscript] nsISupports  getAsISupports();
+    [noscript] jsval        getAsJSVal();
+
+    [noscript] void getAsInterface(out nsIIDPtr iid, 
+                                   [iid_is(iid), retval] out nsQIResult iface);
+
+    [notxpcom] nsresult getAsArray(out uint16_t type, out nsIID iid,
+                                   out uint32_t count, out voidPtr ptr);
+
+    [noscript] void getAsStringWithSize(out uint32_t size, 
+                                        [size_is(size), retval] out string str);
+    
+    [noscript] void getAsWStringWithSize(out uint32_t size, 
+                                         [size_is(size), retval] out wstring str);
+};
+
+/**
+ * An object that implements nsIVariant may or may NOT also implement this
+ * nsIWritableVariant.
+ * 
+ * If the 'writable' attribute is false then attempts to call any of the 'set'
+ * methods can be expected to fail. Setting the 'writable' attribute may or
+ * may not succeed.
+ *
+ */
+
+[scriptable, uuid(5586a590-8c82-11d5-90f3-0010a4e73d9a)]
+interface nsIWritableVariant : nsIVariant
+{
+    attribute boolean writable;
+
+    void setAsInt8(in uint8_t aValue);
+    void setAsInt16(in int16_t aValue);
+    void setAsInt32(in int32_t aValue);
+    void setAsInt64(in int64_t aValue);
+    void setAsUint8(in uint8_t aValue);
+    void setAsUint16(in uint16_t aValue);
+    void setAsUint32(in uint32_t aValue);
+    void setAsUint64(in uint64_t aValue);
+    void setAsFloat(in float aValue);
+    void setAsDouble(in double aValue);
+    void setAsBool(in boolean aValue);
+    void setAsChar(in char aValue);
+    void setAsWChar(in wchar aValue);
+    void setAsID(in nsIDRef aValue);
+    void setAsAString(in AString aValue);
+    void setAsDOMString(in DOMString aValue);
+    void setAsACString(in ACString aValue);
+    void setAsAUTF8String(in AUTF8String aValue);
+    void setAsString(in string aValue);
+    void setAsWString(in wstring aValue);
+    void setAsISupports(in nsISupports aValue);
+
+    void setAsInterface(in nsIIDRef iid, 
+                        [iid_is(iid)] in nsQIResult iface);
+
+    [noscript] void setAsArray(in uint16_t type, in nsIIDPtr iid,
+                               in uint32_t count, in voidPtr ptr);
+
+    void setAsStringWithSize(in uint32_t size, 
+                             [size_is(size)] in string str);
+    
+    void setAsWStringWithSize(in uint32_t size, 
+                              [size_is(size)] in wstring str);
+
+    void setAsVoid();
+    void setAsEmpty();
+    void setAsEmptyArray();
+
+    void setFromVariant(in nsIVariant aValue);
+};
+
+%{C++
+// The contractID for the generic implementation built in to xpcom.
+#define NS_VARIANT_CONTRACTID "@mozilla.org/variant;1"
+%}
diff --git a/xpcom/ds/nsIWindowsRegKey.idl b/xpcom/ds/nsIWindowsRegKey.idl
new file mode 100644
index 000000000..25be0995b
--- /dev/null
+++ b/xpcom/ds/nsIWindowsRegKey.idl
@@ -0,0 +1,332 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+native HKEY(HKEY);
+
+/**
+ * This interface is designed to provide scriptable access to the Windows
+ * registry system ("With Great Power Comes Great Responsibility").  The
+ * interface represents a single key in the registry.
+ *
+ * This interface is highly Win32 specific.
+ */
+[scriptable, uuid(2555b930-d64f-437e-9be7-0a2cb252c1f4)]
+interface nsIWindowsRegKey : nsISupports
+{
+  /**
+   * Root keys.  The values for these keys correspond to the values from
+   * WinReg.h in the MS Platform SDK.  The ROOT_KEY_ prefix corresponds to the
+   * HKEY_ prefix in the MS Platform SDK.
+   *
+   * This interface is not restricted to using only these root keys.
+   */
+  const unsigned long ROOT_KEY_CLASSES_ROOT     = 0x80000000;
+  const unsigned long ROOT_KEY_CURRENT_USER     = 0x80000001;
+  const unsigned long ROOT_KEY_LOCAL_MACHINE    = 0x80000002;
+
+  /**
+   * Values for the mode parameter passed to the open and create methods.
+   * The values defined here correspond to the REGSAM values defined in
+   * WinNT.h in the MS Platform SDK, where ACCESS_ is replaced with KEY_.
+   *
+   * This interface is not restricted to using only these access types.
+   */
+  const unsigned long ACCESS_BASIC              = 0x00020000;
+  const unsigned long ACCESS_QUERY_VALUE        = 0x00000001;
+  const unsigned long ACCESS_SET_VALUE          = 0x00000002;
+  const unsigned long ACCESS_CREATE_SUB_KEY     = 0x00000004;
+  const unsigned long ACCESS_ENUMERATE_SUB_KEYS = 0x00000008;
+  const unsigned long ACCESS_NOTIFY             = 0x00000010;
+  const unsigned long ACCESS_READ               = ACCESS_BASIC |
+                                                  ACCESS_QUERY_VALUE |
+                                                  ACCESS_ENUMERATE_SUB_KEYS |
+                                                  ACCESS_NOTIFY;
+  const unsigned long ACCESS_WRITE              = ACCESS_BASIC |
+                                                  ACCESS_SET_VALUE |
+                                                  ACCESS_CREATE_SUB_KEY;
+  const unsigned long ACCESS_ALL                = ACCESS_READ |
+                                                  ACCESS_WRITE;
+  const unsigned long WOW64_32                  = 0x00000200;
+  const unsigned long WOW64_64                  = 0x00000100;
+
+
+  /**
+   * Values for the type of a registry value.  The numeric values of these
+   * constants are taken directly from WinNT.h in the MS Platform SDK.
+   * The Microsoft documentation should be consulted for the exact meaning of
+   * these value types.
+   *
+   * This interface is somewhat restricted to using only these value types.
+   * There is no method that is directly equivalent to RegQueryValueEx or
+   * RegSetValueEx.  In particular, this interface does not support the
+   * REG_MULTI_SZ and REG_EXPAND_SZ value types.  It is still possible to
+   * enumerate values that have other types (i.e., getValueType may return a
+   * type not defined below).
+   */
+  const unsigned long TYPE_NONE   = 0;  // REG_NONE
+  const unsigned long TYPE_STRING = 1;  // REG_SZ
+  const unsigned long TYPE_BINARY = 3;  // REG_BINARY
+  const unsigned long TYPE_INT    = 4;  // REG_DWORD
+  const unsigned long TYPE_INT64  = 11; // REG_QWORD
+
+  /**
+   * This attribute exposes the native HKEY and is available to provide C++
+   * consumers with the flexibility of making other Windows registry API calls
+   * that are not exposed via this interface.
+   * 
+   * It is possible to initialize this object by setting an HKEY on it.  In
+   * that case, it is the responsibility of the consumer setting the HKEY to
+   * ensure that it is a valid HKEY.
+   *
+   * WARNING: Setting the key does not close the old key.
+   */
+  [noscript] attribute HKEY key;
+
+  /**
+   * This method closes the key.  If the key is already closed, then this
+   * method does nothing.
+   */
+  void close();
+
+  /**
+   * This method opens an existing key.  This method fails if the key
+   * does not exist.
+   *
+   * NOTE: On 32-bit Windows, it is valid to pass any HKEY as the rootKey
+   * parameter of this function.  However, for compatibility with 64-bit
+   * Windows, that usage should probably be avoided in favor of openChild.
+   *
+   * @param rootKey
+   *        A root key defined above or any valid HKEY on 32-bit Windows.
+   * @param relPath
+   *        A relative path from the given root key.
+   * @param mode
+   *        Access mode, which is a bit-wise OR of the ACCESS_ values defined
+   *        above.
+   */
+  void open(in unsigned long rootKey, in AString relPath, in unsigned long mode);
+
+  /**
+   * This method opens an existing key or creates a new key.
+   *
+   * NOTE: On 32-bit Windows, it is valid to pass any HKEY as the rootKey
+   * parameter of this function.  However, for compatibility with 64-bit
+   * Windows, that usage should probably be avoided in favor of createChild.
+   *
+   * @param rootKey
+   *        A root key defined above or any valid HKEY on 32-bit Windows.
+   * @param relPath
+   *        A relative path from the given root key.
+   * @param mode
+   *        Access mode, which is a bit-wise OR of the ACCESS_ values defined
+   *        above.
+   */
+  void create(in unsigned long rootKey, in AString relPath, in unsigned long mode);
+
+  /**
+   * This method opens a subkey relative to this key.  This method fails if the
+   * key does not exist.
+   *
+   * @return nsIWindowsRegKey for the newly opened subkey.
+   */
+  nsIWindowsRegKey openChild(in AString relPath, in unsigned long mode);
+
+  /**
+   * This method opens or creates a subkey relative to this key.
+   *
+   * @return nsIWindowsRegKey for the newly opened or created subkey.
+   */
+  nsIWindowsRegKey createChild(in AString relPath, in unsigned long mode);
+
+  /**
+   * This attribute returns the number of child keys.
+   */
+  readonly attribute unsigned long childCount;
+
+  /**
+   * This method returns the name of the n'th child key.
+   *
+   * @param index
+   *        The index of the requested child key.
+   */
+  AString getChildName(in unsigned long index);
+
+  /**
+   * This method checks to see if the key has a child by the given name.
+   *
+   * @param name
+   *        The name of the requested child key.
+   */
+  boolean hasChild(in AString name);
+
+  /**
+   * This attribute returns the number of values under this key.
+   */
+  readonly attribute unsigned long valueCount;
+
+  /**
+   * This method returns the name of the n'th value under this key.
+   *
+   * @param index
+   *        The index of the requested value.
+   */
+  AString getValueName(in unsigned long index);
+
+  /**
+   * This method checks to see if the key has a value by the given name.
+   *
+   * @param name
+   *        The name of the requested value.
+   */
+  boolean hasValue(in AString name);
+
+  /**
+   * This method removes a child key and all of its values.  This method will
+   * fail if the key has any children of its own. 
+   *
+   * @param relPath
+   *        The relative path from this key to the key to be removed.
+   */
+  void removeChild(in AString relPath);
+
+  /**
+   * This method removes the value with the given name.
+   *
+   * @param name
+   *        The name of the value to be removed.
+   */
+  void removeValue(in AString name);
+
+  /**
+   * This method returns the type of the value with the given name.  The return
+   * value is one of the "TYPE_" constants defined above.
+   *
+   * @param name
+   *        The name of the value to query.
+   */
+  unsigned long getValueType(in AString name);
+
+  /**
+   * This method reads the string contents of the named value as a Unicode
+   * string.
+   *
+   * @param name
+   *        The name of the value to query.  This parameter can be the empty
+   *        string to request the key's default value.
+   */
+  AString readStringValue(in AString name);
+
+  /**
+   * This method reads the integer contents of the named value.
+   *
+   * @param name
+   *        The name of the value to query.
+   */
+  unsigned long readIntValue(in AString name);
+
+  /**
+   * This method reads the 64-bit integer contents of the named value.
+   *
+   * @param name
+   *        The name of the value to query.
+   */
+  unsigned long long readInt64Value(in AString name);
+
+  /**
+   * This method reads the binary contents of the named value under this key.
+   *
+   * JavaScript callers should take care with the result of this method since
+   * it will be byte-expanded to form a JS string.  (The binary data will be
+   * treated as an ISO-Latin-1 character string, which it is not).
+   *
+   * @param name
+   *        The name of the value to query.
+   */
+  ACString readBinaryValue(in AString name);
+
+  /**
+   * This method writes the unicode string contents of the named value.  The
+   * value will be created if it does not already exist.
+   *
+   * @param name
+   *        The name of the value to modify.  This parameter can be the empty
+   *        string to modify the key's default value.
+   * @param data
+   *        The data for the value to modify.
+   */
+  void writeStringValue(in AString name, in AString data);
+
+  /**
+   * This method writes the integer contents of the named value.  The value
+   * will be created if it does not already exist.
+   *
+   * @param name
+   *        The name of the value to modify.
+   * @param data
+   *        The data for the value to modify.
+   */
+  void writeIntValue(in AString name, in unsigned long data);
+
+  /**
+   * This method writes the 64-bit integer contents of the named value.  The
+   * value will be created if it does not already exist.
+   *
+   * @param name
+   *        The name of the value to modify.
+   * @param data
+   *        The data for the value to modify.
+   */
+  void writeInt64Value(in AString name, in unsigned long long data);
+
+  /**
+   * This method writes the binary contents of the named value.  The value will
+   * be created if it does not already exist.
+   * 
+   * JavaScript callers should take care with the value passed to this method
+   * since it will be truncated from a JS string (unicode) to a ISO-Latin-1
+   * string.  (The binary data will be treated as an ISO-Latin-1 character
+   * string, which it is not).  So, JavaScript callers should only pass
+   * character values in the range \u0000 to \u00FF, or else data loss will
+   * occur.
+   *
+   * @param name
+   *        The name of the value to modify.
+   * @param data
+   *        The data for the value to modify.
+   */
+  void writeBinaryValue(in AString name, in ACString data);
+
+  /**
+   * This method starts watching the key to see if any of its values have
+   * changed.  The key must have been opened with mode including ACCESS_NOTIFY.
+   * If recurse is true, then this key and any of its descendant keys are
+   * watched.  Otherwise, only this key is watched.
+   *
+   * @param recurse
+   *        Indicates whether or not to also watch child keys.
+   */
+  void startWatching(in boolean recurse);
+
+  /**
+   * This method stops any watching of the key initiated by a call to
+   * startWatching.  This method does nothing if the key is not being watched.
+   */
+  void stopWatching();
+
+  /**
+   * This method returns true if the key is being watched for changes (i.e.,
+   * if startWatching() was called).
+   */
+  boolean isWatching();
+
+  /**
+   * This method returns true if the key has changed and false otherwise.
+   * This method will always return false if startWatching was not called.
+   */
+  boolean hasChanged();
+};
diff --git a/xpcom/ds/nsIWritablePropertyBag.idl b/xpcom/ds/nsIWritablePropertyBag.idl
new file mode 100644
index 000000000..e916b7ccd
--- /dev/null
+++ b/xpcom/ds/nsIWritablePropertyBag.idl
@@ -0,0 +1,27 @@
+/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* nsIVariant based writable Property Bag support. */
+
+#include "nsIPropertyBag.idl"
+
+[scriptable, uuid(96fc4671-eeb4-4823-9421-e50fb70ad353)]
+interface nsIWritablePropertyBag : nsIPropertyBag
+{
+    /**
+     * Set a property with the given name to the given value.  If
+     * a property already exists with the given name, it is
+     * overwritten.
+     */
+    void setProperty(in AString name, in nsIVariant value);
+
+    /**
+     * Delete a property with the given name.
+     * @throws NS_ERROR_FAILURE if a property with that name doesn't
+     * exist.
+     */
+    void deleteProperty(in AString name);
+};
diff --git a/xpcom/ds/nsIWritablePropertyBag2.idl b/xpcom/ds/nsIWritablePropertyBag2.idl
new file mode 100644
index 000000000..50f093905
--- /dev/null
+++ b/xpcom/ds/nsIWritablePropertyBag2.idl
@@ -0,0 +1,22 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* nsIVariant based Property Bag support. */
+
+#include "nsIPropertyBag2.idl"
+
+[scriptable, uuid(9cfd1587-360e-4957-a58f-4c2b1c5e7ed9)]
+interface nsIWritablePropertyBag2 : nsIPropertyBag2
+{
+  void        setPropertyAsInt32       (in AString prop, in int32_t value);
+  void        setPropertyAsUint32      (in AString prop, in uint32_t value);
+  void        setPropertyAsInt64       (in AString prop, in int64_t value);
+  void        setPropertyAsUint64      (in AString prop, in uint64_t value);
+  void        setPropertyAsDouble      (in AString prop, in double value);
+  void        setPropertyAsAString     (in AString prop, in AString value);
+  void        setPropertyAsACString    (in AString prop, in ACString value);
+  void        setPropertyAsAUTF8String (in AString prop, in AUTF8String value);
+  void        setPropertyAsBool        (in AString prop, in boolean value);
+  void        setPropertyAsInterface   (in AString prop, in nsISupports value);
+};
diff --git a/xpcom/ds/nsMathUtils.h b/xpcom/ds/nsMathUtils.h
new file mode 100644
index 000000000..b10b8144e
--- /dev/null
+++ b/xpcom/ds/nsMathUtils.h
@@ -0,0 +1,127 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMathUtils_h__
+#define nsMathUtils_h__
+
+#include "nscore.h"
+#include <cmath>
+#include <float.h>
+
+#ifdef SOLARIS
+#include <ieeefp.h>
+#endif
+
+/*
+ * round
+ */
+inline double
+NS_round(double aNum)
+{
+  return aNum >= 0.0 ? floor(aNum + 0.5) : ceil(aNum - 0.5);
+}
+inline float
+NS_roundf(float aNum)
+{
+  return aNum >= 0.0f ? floorf(aNum + 0.5f) : ceilf(aNum - 0.5f);
+}
+inline int32_t
+NS_lround(double aNum)
+{
+  return aNum >= 0.0 ? int32_t(aNum + 0.5) : int32_t(aNum - 0.5);
+}
+
+/* NS_roundup30 rounds towards infinity for positive and       */
+/* negative numbers.                                           */
+
+#if defined(XP_WIN32) && defined(_M_IX86) && !defined(__GNUC__) && !defined(__clang__)
+inline int32_t NS_lroundup30(float x)
+{
+  /* Code derived from Laurent de Soras' paper at             */
+  /* http://ldesoras.free.fr/doc/articles/rounding_en.pdf     */
+
+  /* Rounding up on Windows is expensive using the float to   */
+  /* int conversion and the floor function. A faster          */
+  /* approach is to use f87 rounding while assuming the       */
+  /* default rounding mode of rounding to the nearest         */
+  /* integer. This rounding mode, however, actually rounds    */
+  /* to the nearest integer so we add the floating point      */
+  /* number to itself and add our rounding factor before      */
+  /* doing the conversion to an integer. We then do a right   */
+  /* shift of one bit on the integer to divide by two.        */
+
+  /* This routine doesn't handle numbers larger in magnitude  */
+  /* than 2^30 but this is fine for NSToCoordRound because    */
+  /* Coords are limited to 2^30 in magnitude.                 */
+
+  static const double round_to_nearest = 0.5f;
+  int i;
+
+  __asm {
+    fld     x                   ; load fp argument
+    fadd    st, st(0)           ; double it
+    fadd    round_to_nearest    ; add the rounding factor
+    fistp   dword ptr i         ; convert the result to int
+  }
+  return i >> 1;                /* divide by 2 */
+}
+#endif /* XP_WIN32 && _M_IX86 && !__GNUC__ */
+
+inline int32_t
+NS_lroundf(float aNum)
+{
+  return aNum >= 0.0f ? int32_t(aNum + 0.5f) : int32_t(aNum - 0.5f);
+}
+
+/*
+ * hypot.  We don't need a super accurate version of this, if a platform
+ * turns up with none of the possibilities below it would be okay to fall
+ * back to sqrt(x*x + y*y).
+ */
+inline double
+NS_hypot(double aNum1, double aNum2)
+{
+#ifdef __GNUC__
+  return __builtin_hypot(aNum1, aNum2);
+#elif defined _WIN32
+  return _hypot(aNum1, aNum2);
+#else
+  return hypot(aNum1, aNum2);
+#endif
+}
+
+/**
+ * Check whether a floating point number is finite (not +/-infinity and not a
+ * NaN value).
+ */
+inline bool
+NS_finite(double aNum)
+{
+#ifdef WIN32
+  // NOTE: '!!' casts an int to bool without spamming MSVC warning C4800.
+  return !!_finite(aNum);
+#elif defined(XP_DARWIN)
+  // Darwin has deprecated |finite| and recommends |isfinite|. The former is
+  // not present in the iOS SDK.
+  return std::isfinite(aNum);
+#else
+  return finite(aNum);
+#endif
+}
+
+/**
+ * Returns the result of the modulo of x by y using a floored division.
+ * fmod(x, y) is using a truncated division.
+ * The main difference is that the result of this method will have the sign of
+ * y while the result of fmod(x, y) will have the sign of x.
+ */
+inline double
+NS_floorModulo(double aNum1, double aNum2)
+{
+  return (aNum1 - aNum2 * floor(aNum1 / aNum2));
+}
+
+#endif
diff --git a/xpcom/ds/nsObserverList.cpp b/xpcom/ds/nsObserverList.cpp
new file mode 100644
index 000000000..fef8831b8
--- /dev/null
+++ b/xpcom/ds/nsObserverList.cpp
@@ -0,0 +1,142 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsObserverList.h"
+
+#include "nsAutoPtr.h"
+#include "nsCOMArray.h"
+#include "nsISimpleEnumerator.h"
+#include "xpcpublic.h"
+
+nsresult
+nsObserverList::AddObserver(nsIObserver* anObserver, bool ownsWeak)
+{
+  NS_ASSERTION(anObserver, "Null input");
+
+  if (!ownsWeak) {
+    ObserverRef* o = mObservers.AppendElement(anObserver);
+    if (!o) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIWeakReference> weak = do_GetWeakReference(anObserver);
+  if (!weak) {
+    return NS_NOINTERFACE;
+  }
+
+  ObserverRef* o = mObservers.AppendElement(weak);
+  if (!o) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  return NS_OK;
+}
+
+nsresult
+nsObserverList::RemoveObserver(nsIObserver* anObserver)
+{
+  NS_ASSERTION(anObserver, "Null input");
+
+  if (mObservers.RemoveElement(static_cast<nsISupports*>(anObserver))) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIWeakReference> observerRef = do_GetWeakReference(anObserver);
+  if (!observerRef) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (!mObservers.RemoveElement(observerRef)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+void
+nsObserverList::GetObserverList(nsISimpleEnumerator** anEnumerator)
+{
+  RefPtr<nsObserverEnumerator> e(new nsObserverEnumerator(this));
+  e.forget(anEnumerator);
+}
+
+void
+nsObserverList::FillObserverArray(nsCOMArray<nsIObserver>& aArray)
+{
+  aArray.SetCapacity(mObservers.Length());
+
+  nsTArray<ObserverRef> observers(mObservers);
+
+  for (int32_t i = observers.Length() - 1; i >= 0; --i) {
+    if (observers[i].isWeakRef) {
+      nsCOMPtr<nsIObserver> o(do_QueryReferent(observers[i].asWeak()));
+      if (o) {
+        aArray.AppendObject(o);
+      } else {
+        // the object has gone away, remove the weakref
+        mObservers.RemoveElement(observers[i].asWeak());
+      }
+    } else {
+      aArray.AppendObject(observers[i].asObserver());
+    }
+  }
+}
+
+void
+nsObserverList::AppendStrongObservers(nsCOMArray<nsIObserver>& aArray)
+{
+  aArray.SetCapacity(aArray.Length() + mObservers.Length());
+
+  for (int32_t i = mObservers.Length() - 1; i >= 0; --i) {
+    if (!mObservers[i].isWeakRef) {
+      aArray.AppendObject(mObservers[i].asObserver());
+    }
+  }
+}
+
+void
+nsObserverList::NotifyObservers(nsISupports* aSubject,
+                                const char* aTopic,
+                                const char16_t* someData)
+{
+  nsCOMArray<nsIObserver> observers;
+  FillObserverArray(observers);
+
+  for (int32_t i = 0; i < observers.Count(); ++i) {
+    observers[i]->Observe(aSubject, aTopic, someData);
+  }
+}
+
+NS_IMPL_ISUPPORTS(nsObserverEnumerator, nsISimpleEnumerator)
+
+nsObserverEnumerator::nsObserverEnumerator(nsObserverList* aObserverList)
+  : mIndex(0)
+{
+  aObserverList->FillObserverArray(mObservers);
+}
+
+NS_IMETHODIMP
+nsObserverEnumerator::HasMoreElements(bool* aResult)
+{
+  *aResult = (mIndex < mObservers.Count());
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsObserverEnumerator::GetNext(nsISupports** aResult)
+{
+  if (mIndex == mObservers.Count()) {
+    NS_ERROR("Enumerating after HasMoreElements returned false.");
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  NS_ADDREF(*aResult = mObservers[mIndex]);
+  ++mIndex;
+  return NS_OK;
+}
diff --git a/xpcom/ds/nsObserverList.h b/xpcom/ds/nsObserverList.h
new file mode 100644
index 000000000..90a685ea6
--- /dev/null
+++ b/xpcom/ds/nsObserverList.h
@@ -0,0 +1,93 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsObserverList_h___
+#define nsObserverList_h___
+
+#include "nsISupports.h"
+#include "nsTArray.h"
+#include "nsCOMPtr.h"
+#include "nsCOMArray.h"
+#include "nsIObserver.h"
+#include "nsIWeakReference.h"
+#include "nsHashKeys.h"
+#include "nsISimpleEnumerator.h"
+#include "mozilla/Attributes.h"
+
+struct ObserverRef
+{
+  ObserverRef(const ObserverRef& aO) : isWeakRef(aO.isWeakRef), ref(aO.ref) {}
+  explicit ObserverRef(nsIObserver* aObserver) : isWeakRef(false), ref(aObserver) {}
+  explicit ObserverRef(nsIWeakReference* aWeak) : isWeakRef(true), ref(aWeak) {}
+
+  bool isWeakRef;
+  nsCOMPtr<nsISupports> ref;
+
+  nsIObserver* asObserver()
+  {
+    NS_ASSERTION(!isWeakRef, "Isn't a strong ref.");
+    return static_cast<nsIObserver*>((nsISupports*)ref);
+  }
+
+  nsIWeakReference* asWeak()
+  {
+    NS_ASSERTION(isWeakRef, "Isn't a weak ref.");
+    return static_cast<nsIWeakReference*>((nsISupports*)ref);
+  }
+
+  bool operator==(nsISupports* aRhs) const { return ref == aRhs; }
+};
+
+class nsObserverList : public nsCharPtrHashKey
+{
+  friend class nsObserverService;
+
+public:
+  explicit nsObserverList(const char* aKey) : nsCharPtrHashKey(aKey)
+  {
+    MOZ_COUNT_CTOR(nsObserverList);
+  }
+
+  ~nsObserverList()
+  {
+    MOZ_COUNT_DTOR(nsObserverList);
+  }
+
+  MOZ_MUST_USE nsresult AddObserver(nsIObserver* aObserver, bool aOwnsWeak);
+  MOZ_MUST_USE nsresult RemoveObserver(nsIObserver* aObserver);
+
+  void NotifyObservers(nsISupports* aSubject,
+                       const char* aTopic,
+                       const char16_t* aSomeData);
+  void GetObserverList(nsISimpleEnumerator** aEnumerator);
+
+  // Fill an array with the observers of this category.
+  // The array is filled in last-added-first order.
+  void FillObserverArray(nsCOMArray<nsIObserver>& aArray);
+
+  // Like FillObserverArray(), but only for strongly held observers.
+  void AppendStrongObservers(nsCOMArray<nsIObserver>& aArray);
+
+private:
+  nsTArray<ObserverRef> mObservers;
+};
+
+class nsObserverEnumerator final : public nsISimpleEnumerator
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISIMPLEENUMERATOR
+
+  explicit nsObserverEnumerator(nsObserverList* aObserverList);
+
+private:
+  ~nsObserverEnumerator() {}
+
+  int32_t mIndex; // Counts up from 0
+  nsCOMArray<nsIObserver> mObservers;
+};
+
+#endif /* nsObserverList_h___ */
diff --git a/xpcom/ds/nsObserverService.cpp b/xpcom/ds/nsObserverService.cpp
new file mode 100644
index 000000000..23cc54fa7
--- /dev/null
+++ b/xpcom/ds/nsObserverService.cpp
@@ -0,0 +1,312 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Logging.h"
+#include "nsAutoPtr.h"
+#include "nsIConsoleService.h"
+#include "nsIObserverService.h"
+#include "nsIObserver.h"
+#include "nsIScriptError.h"
+#include "nsObserverService.h"
+#include "nsObserverList.h"
+#include "nsServiceManagerUtils.h"
+#include "nsThreadUtils.h"
+#include "nsEnumeratorUtils.h"
+#include "xpcpublic.h"
+#include "mozilla/net/NeckoCommon.h"
+#include "mozilla/Services.h"
+
+#define NOTIFY_GLOBAL_OBSERVERS
+
+// Log module for nsObserverService logging...
+//
+// To enable logging (see prlog.h for full details):
+//
+//    set MOZ_LOG=ObserverService:5
+//    set MOZ_LOG_FILE=service.log
+//
+// This enables LogLevel::Debug level information and places all output in
+// the file service.log.
+static mozilla::LazyLogModule sObserverServiceLog("ObserverService");
+#define LOG(x) MOZ_LOG(sObserverServiceLog, mozilla::LogLevel::Debug, x)
+
+using namespace mozilla;
+
+NS_IMETHODIMP
+nsObserverService::CollectReports(nsIHandleReportCallback* aHandleReport,
+                                  nsISupports* aData, bool aAnonymize)
+{
+  struct SuspectObserver
+  {
+    SuspectObserver(const char* aTopic, size_t aReferentCount)
+      : mTopic(aTopic)
+      , mReferentCount(aReferentCount)
+    {}
+    const char* mTopic;
+    size_t mReferentCount;
+  };
+
+  size_t totalNumStrong = 0;
+  size_t totalNumWeakAlive = 0;
+  size_t totalNumWeakDead = 0;
+  nsTArray<SuspectObserver> suspectObservers;
+
+  for (auto iter = mObserverTopicTable.Iter(); !iter.Done(); iter.Next()) {
+    nsObserverList* observerList = iter.Get();
+    if (!observerList) {
+      continue;
+    }
+
+    size_t topicNumStrong = 0;
+    size_t topicNumWeakAlive = 0;
+    size_t topicNumWeakDead = 0;
+
+    nsTArray<ObserverRef>& observers = observerList->mObservers;
+    for (uint32_t i = 0; i < observers.Length(); i++) {
+      if (observers[i].isWeakRef) {
+        nsCOMPtr<nsIObserver> observerRef(
+          do_QueryReferent(observers[i].asWeak()));
+        if (observerRef) {
+          topicNumWeakAlive++;
+        } else {
+          topicNumWeakDead++;
+        }
+      } else {
+        topicNumStrong++;
+      }
+    }
+
+    totalNumStrong += topicNumStrong;
+    totalNumWeakAlive += topicNumWeakAlive;
+    totalNumWeakDead += topicNumWeakDead;
+
+    // Keep track of topics that have a suspiciously large number
+    // of referents (symptom of leaks).
+    size_t topicTotal = topicNumStrong + topicNumWeakAlive + topicNumWeakDead;
+    if (topicTotal > kSuspectReferentCount) {
+      SuspectObserver suspect(observerList->GetKey(), topicTotal);
+      suspectObservers.AppendElement(suspect);
+    }
+  }
+
+  // These aren't privacy-sensitive and so don't need anonymizing.
+  for (uint32_t i = 0; i < suspectObservers.Length(); i++) {
+    SuspectObserver& suspect = suspectObservers[i];
+    nsPrintfCString suspectPath("observer-service-suspect/referent(topic=%s)",
+                                suspect.mTopic);
+    aHandleReport->Callback(
+      /* process */ EmptyCString(),
+      suspectPath, KIND_OTHER, UNITS_COUNT, suspect.mReferentCount,
+      NS_LITERAL_CSTRING("A topic with a suspiciously large number of "
+                         "referents.  This may be symptomatic of a leak "
+                         "if the number of referents is high with "
+                         "respect to the number of windows."),
+      aData);
+  }
+
+  MOZ_COLLECT_REPORT(
+    "observer-service/referent/strong", KIND_OTHER, UNITS_COUNT,
+    totalNumStrong,
+    "The number of strong references held by the observer service.");
+
+  MOZ_COLLECT_REPORT(
+    "observer-service/referent/weak/alive", KIND_OTHER, UNITS_COUNT,
+    totalNumWeakAlive,
+    "The number of weak references held by the observer service that are "
+    "still alive.");
+
+  MOZ_COLLECT_REPORT(
+    "observer-service/referent/weak/dead", KIND_OTHER, UNITS_COUNT,
+    totalNumWeakDead,
+    "The number of weak references held by the observer service that are "
+    "dead.");
+
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// nsObserverService Implementation
+
+NS_IMPL_ISUPPORTS(nsObserverService,
+                  nsIObserverService,
+                  nsObserverService,
+                  nsIMemoryReporter)
+
+nsObserverService::nsObserverService()
+  : mShuttingDown(false)
+{
+}
+
+nsObserverService::~nsObserverService(void)
+{
+  Shutdown();
+}
+
+void
+nsObserverService::RegisterReporter()
+{
+  RegisterWeakMemoryReporter(this);
+}
+
+void
+nsObserverService::Shutdown()
+{
+  UnregisterWeakMemoryReporter(this);
+
+  mShuttingDown = true;
+
+  mObserverTopicTable.Clear();
+}
+
+nsresult
+nsObserverService::Create(nsISupports* aOuter, const nsIID& aIID,
+                          void** aInstancePtr)
+{
+  LOG(("nsObserverService::Create()"));
+
+  RefPtr<nsObserverService> os = new nsObserverService();
+
+  if (!os) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  // The memory reporter can not be immediately registered here because
+  // the nsMemoryReporterManager may attempt to get the nsObserverService
+  // during initialization, causing a recursive GetService.
+  NS_DispatchToCurrentThread(NewRunnableMethod(os, &nsObserverService::RegisterReporter));
+
+  return os->QueryInterface(aIID, aInstancePtr);
+}
+
+#define NS_ENSURE_VALIDCALL \
+    if (!NS_IsMainThread()) {                                     \
+        MOZ_CRASH("Using observer service off the main thread!"); \
+        return NS_ERROR_UNEXPECTED;                               \
+    }                                                             \
+    if (mShuttingDown) {                                          \
+        NS_ERROR("Using observer service after XPCOM shutdown!"); \
+        return NS_ERROR_ILLEGAL_DURING_SHUTDOWN;                  \
+    }
+
+NS_IMETHODIMP
+nsObserverService::AddObserver(nsIObserver* aObserver, const char* aTopic,
+                               bool aOwnsWeak)
+{
+  LOG(("nsObserverService::AddObserver(%p: %s)",
+       (void*)aObserver, aTopic));
+
+  NS_ENSURE_VALIDCALL
+  if (NS_WARN_IF(!aObserver) || NS_WARN_IF(!aTopic)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // Specifically allow http-on-opening-request in the child process;
+  // see bug 1269765.
+  if (mozilla::net::IsNeckoChild() && !strncmp(aTopic, "http-on-", 8) &&
+      strcmp(aTopic, "http-on-opening-request")) {
+    nsCOMPtr<nsIConsoleService> console(do_GetService(NS_CONSOLESERVICE_CONTRACTID));
+    nsCOMPtr<nsIScriptError> error(do_CreateInstance(NS_SCRIPTERROR_CONTRACTID));
+    error->Init(NS_LITERAL_STRING("http-on-* observers only work in the parent process"),
+                EmptyString(), EmptyString(), 0, 0,
+                nsIScriptError::warningFlag, "chrome javascript");
+    console->LogMessage(error);
+
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  nsObserverList* observerList = mObserverTopicTable.PutEntry(aTopic);
+  if (!observerList) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  return observerList->AddObserver(aObserver, aOwnsWeak);
+}
+
+NS_IMETHODIMP
+nsObserverService::RemoveObserver(nsIObserver* aObserver, const char* aTopic)
+{
+  LOG(("nsObserverService::RemoveObserver(%p: %s)",
+       (void*)aObserver, aTopic));
+  NS_ENSURE_VALIDCALL
+  if (NS_WARN_IF(!aObserver) || NS_WARN_IF(!aTopic)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsObserverList* observerList = mObserverTopicTable.GetEntry(aTopic);
+  if (!observerList) {
+    return NS_ERROR_FAILURE;
+  }
+
+  /* This death grip is to protect against stupid consumers who call
+     RemoveObserver from their Destructor, see bug 485834/bug 325392. */
+  nsCOMPtr<nsIObserver> kungFuDeathGrip(aObserver);
+  return observerList->RemoveObserver(aObserver);
+}
+
+NS_IMETHODIMP
+nsObserverService::EnumerateObservers(const char* aTopic,
+                                      nsISimpleEnumerator** anEnumerator)
+{
+  NS_ENSURE_VALIDCALL
+  if (NS_WARN_IF(!anEnumerator) || NS_WARN_IF(!aTopic)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsObserverList* observerList = mObserverTopicTable.GetEntry(aTopic);
+  if (!observerList) {
+    return NS_NewEmptyEnumerator(anEnumerator);
+  }
+
+  observerList->GetObserverList(anEnumerator);
+  return NS_OK;
+}
+
+// Enumerate observers of aTopic and call Observe on each.
+NS_IMETHODIMP nsObserverService::NotifyObservers(nsISupports* aSubject,
+                                                 const char* aTopic,
+                                                 const char16_t* aSomeData)
+{
+  LOG(("nsObserverService::NotifyObservers(%s)", aTopic));
+
+  NS_ENSURE_VALIDCALL
+  if (NS_WARN_IF(!aTopic)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsObserverList* observerList = mObserverTopicTable.GetEntry(aTopic);
+  if (observerList) {
+    observerList->NotifyObservers(aSubject, aTopic, aSomeData);
+  }
+
+#ifdef NOTIFY_GLOBAL_OBSERVERS
+  observerList = mObserverTopicTable.GetEntry("*");
+  if (observerList) {
+    observerList->NotifyObservers(aSubject, aTopic, aSomeData);
+  }
+#endif
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsObserverService::UnmarkGrayStrongObservers()
+{
+  NS_ENSURE_VALIDCALL
+
+  nsCOMArray<nsIObserver> strongObservers;
+  for (auto iter = mObserverTopicTable.Iter(); !iter.Done(); iter.Next()) {
+    nsObserverList* aObserverList = iter.Get();
+    if (aObserverList) {
+      aObserverList->AppendStrongObservers(strongObservers);
+    }
+  }
+
+  for (uint32_t i = 0; i < strongObservers.Length(); ++i) {
+    xpc_TryUnmarkWrappedGrayObject(strongObservers[i]);
+  }
+
+  return NS_OK;
+}
diff --git a/xpcom/ds/nsObserverService.h b/xpcom/ds/nsObserverService.h
new file mode 100644
index 000000000..fa0d9b9d8
--- /dev/null
+++ b/xpcom/ds/nsObserverService.h
@@ -0,0 +1,55 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsObserverService_h___
+#define nsObserverService_h___
+
+#include "nsIObserverService.h"
+#include "nsObserverList.h"
+#include "nsIMemoryReporter.h"
+#include "nsTHashtable.h"
+#include "mozilla/Attributes.h"
+
+// {D07F5195-E3D1-11d2-8ACD-00105A1B8860}
+#define NS_OBSERVERSERVICE_CID \
+    { 0xd07f5195, 0xe3d1, 0x11d2, { 0x8a, 0xcd, 0x0, 0x10, 0x5a, 0x1b, 0x88, 0x60 } }
+
+class nsIMemoryReporter;
+
+class nsObserverService final
+  : public nsIObserverService
+  , public nsIMemoryReporter
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_OBSERVERSERVICE_CID)
+
+  nsObserverService();
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIOBSERVERSERVICE
+  NS_DECL_NSIMEMORYREPORTER
+
+  void Shutdown();
+
+  static MOZ_MUST_USE nsresult Create(nsISupports* aOuter, const nsIID& aIID,
+                                      void** aInstancePtr);
+
+  // Unmark any strongly held observers implemented in JS so the cycle
+  // collector will not traverse them.
+  NS_IMETHOD UnmarkGrayStrongObservers();
+
+private:
+  ~nsObserverService(void);
+  void RegisterReporter();
+
+  static const size_t kSuspectReferentCount = 100;
+  bool mShuttingDown;
+  nsTHashtable<nsObserverList> mObserverTopicTable;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsObserverService, NS_OBSERVERSERVICE_CID)
+
+#endif /* nsObserverService_h___ */
diff --git a/xpcom/ds/nsPersistentProperties.cpp b/xpcom/ds/nsPersistentProperties.cpp
new file mode 100644
index 000000000..ea925874c
--- /dev/null
+++ b/xpcom/ds/nsPersistentProperties.cpp
@@ -0,0 +1,666 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsArrayEnumerator.h"
+#include "nsID.h"
+#include "nsCOMArray.h"
+#include "nsUnicharInputStream.h"
+#include "nsPrintfCString.h"
+#include "nsAutoPtr.h"
+
+#define PL_ARENA_CONST_ALIGN_MASK 3
+#include "nsPersistentProperties.h"
+#include "nsIProperties.h"
+
+struct PropertyTableEntry : public PLDHashEntryHdr
+{
+  // both of these are arena-allocated
+  const char* mKey;
+  const char16_t* mValue;
+};
+
+static char16_t*
+ArenaStrdup(const nsAFlatString& aString, PLArenaPool* aArena)
+{
+  void* mem;
+  // add one to include the null terminator
+  int32_t len = (aString.Length() + 1) * sizeof(char16_t);
+  PL_ARENA_ALLOCATE(mem, aArena, len);
+  NS_ASSERTION(mem, "Couldn't allocate space!\n");
+  if (mem) {
+    memcpy(mem, aString.get(), len);
+  }
+  return static_cast<char16_t*>(mem);
+}
+
+static char*
+ArenaStrdup(const nsAFlatCString& aString, PLArenaPool* aArena)
+{
+  void* mem;
+  // add one to include the null terminator
+  int32_t len = (aString.Length() + 1) * sizeof(char);
+  PL_ARENA_ALLOCATE(mem, aArena, len);
+  NS_ASSERTION(mem, "Couldn't allocate space!\n");
+  if (mem) {
+    memcpy(mem, aString.get(), len);
+  }
+  return static_cast<char*>(mem);
+}
+
+static const struct PLDHashTableOps property_HashTableOps = {
+  PLDHashTable::HashStringKey,
+  PLDHashTable::MatchStringKey,
+  PLDHashTable::MoveEntryStub,
+  PLDHashTable::ClearEntryStub,
+  nullptr,
+};
+
+//
+// parser stuff
+//
+enum EParserState
+{
+  eParserState_AwaitingKey,
+  eParserState_Key,
+  eParserState_AwaitingValue,
+  eParserState_Value,
+  eParserState_Comment
+};
+
+enum EParserSpecial
+{
+  eParserSpecial_None,          // not parsing a special character
+  eParserSpecial_Escaped,       // awaiting a special character
+  eParserSpecial_Unicode        // parsing a \Uxxx value
+};
+
+class MOZ_STACK_CLASS nsPropertiesParser
+{
+public:
+  explicit nsPropertiesParser(nsIPersistentProperties* aProps)
+    : mHaveMultiLine(false)
+    , mState(eParserState_AwaitingKey)
+    , mProps(aProps)
+  {
+  }
+
+  void FinishValueState(nsAString& aOldValue)
+  {
+    static const char trimThese[] = " \t";
+    mKey.Trim(trimThese, false, true);
+
+    // This is really ugly hack but it should be fast
+    char16_t backup_char;
+    uint32_t minLength = mMinLength;
+    if (minLength) {
+      backup_char = mValue[minLength - 1];
+      mValue.SetCharAt('x', minLength - 1);
+    }
+    mValue.Trim(trimThese, false, true);
+    if (minLength) {
+      mValue.SetCharAt(backup_char, minLength - 1);
+    }
+
+    mProps->SetStringProperty(NS_ConvertUTF16toUTF8(mKey), mValue, aOldValue);
+    mSpecialState = eParserSpecial_None;
+    WaitForKey();
+  }
+
+  EParserState GetState() { return mState; }
+
+  static nsresult SegmentWriter(nsIUnicharInputStream* aStream,
+                                void* aClosure,
+                                const char16_t* aFromSegment,
+                                uint32_t aToOffset,
+                                uint32_t aCount,
+                                uint32_t* aWriteCount);
+
+  nsresult ParseBuffer(const char16_t* aBuffer, uint32_t aBufferLength);
+
+private:
+  bool ParseValueCharacter(
+    char16_t aChar,               // character that is just being parsed
+    const char16_t* aCur,         // pointer to character aChar in the buffer
+    const char16_t*& aTokenStart, // string copying is done in blocks as big as
+                                  // possible, aTokenStart points to the beginning
+                                  // of this block
+    nsAString& aOldValue);        // when duplicate property is found, new value
+                                  // is stored into hashtable and the old one is
+                                  // placed in this variable
+
+  void WaitForKey()
+  {
+    mState = eParserState_AwaitingKey;
+  }
+
+  void EnterKeyState()
+  {
+    mKey.Truncate();
+    mState = eParserState_Key;
+  }
+
+  void WaitForValue()
+  {
+    mState = eParserState_AwaitingValue;
+  }
+
+  void EnterValueState()
+  {
+    mValue.Truncate();
+    mMinLength = 0;
+    mState = eParserState_Value;
+    mSpecialState = eParserSpecial_None;
+  }
+
+  void EnterCommentState()
+  {
+    mState = eParserState_Comment;
+  }
+
+  nsAutoString mKey;
+  nsAutoString mValue;
+
+  uint32_t  mUnicodeValuesRead; // should be 4!
+  char16_t mUnicodeValue;      // currently parsed unicode value
+  bool      mHaveMultiLine;     // is TRUE when last processed characters form
+                                // any of following sequences:
+                                //  - "\\\r"
+                                //  - "\\\n"
+                                //  - "\\\r\n"
+                                //  - any sequence above followed by any
+                                //    combination of ' ' and '\t'
+  bool      mMultiLineCanSkipN; // TRUE if "\\\r" was detected
+  uint32_t  mMinLength;         // limit right trimming at the end to not trim
+                                // escaped whitespaces
+  EParserState mState;
+  // if we see a '\' then we enter this special state
+  EParserSpecial mSpecialState;
+  nsCOMPtr<nsIPersistentProperties> mProps;
+};
+
+inline bool
+IsWhiteSpace(char16_t aChar)
+{
+  return (aChar == ' ') || (aChar == '\t') ||
+         (aChar == '\r') || (aChar == '\n');
+}
+
+inline bool
+IsEOL(char16_t aChar)
+{
+  return (aChar == '\r') || (aChar == '\n');
+}
+
+
+bool
+nsPropertiesParser::ParseValueCharacter(char16_t aChar, const char16_t* aCur,
+                                        const char16_t*& aTokenStart,
+                                        nsAString& aOldValue)
+{
+  switch (mSpecialState) {
+    // the normal state - look for special characters
+    case eParserSpecial_None:
+      switch (aChar) {
+        case '\\':
+          if (mHaveMultiLine) {
+            // there is nothing to append to mValue yet
+            mHaveMultiLine = false;
+          } else {
+            mValue += Substring(aTokenStart, aCur);
+          }
+
+          mSpecialState = eParserSpecial_Escaped;
+          break;
+
+        case '\n':
+          // if we detected multiline and got only "\\\r" ignore next "\n" if any
+          if (mHaveMultiLine && mMultiLineCanSkipN) {
+            // but don't allow another '\n' to be skipped
+            mMultiLineCanSkipN = false;
+            // Now there is nothing to append to the mValue since we are skipping
+            // whitespaces at the beginning of the new line of the multiline
+            // property. Set aTokenStart properly to ensure that nothing is appended
+            // if we find regular line-end or the end of the buffer.
+            aTokenStart = aCur + 1;
+            break;
+          }
+          MOZ_FALLTHROUGH;
+
+        case '\r':
+          // we're done! We have a key and value
+          mValue += Substring(aTokenStart, aCur);
+          FinishValueState(aOldValue);
+          mHaveMultiLine = false;
+          break;
+
+        default:
+          // there is nothing to do with normal characters,
+          // but handle multilines correctly
+          if (mHaveMultiLine) {
+            if (aChar == ' ' || aChar == '\t') {
+              // don't allow another '\n' to be skipped
+              mMultiLineCanSkipN = false;
+              // Now there is nothing to append to the mValue since we are skipping
+              // whitespaces at the beginning of the new line of the multiline
+              // property. Set aTokenStart properly to ensure that nothing is appended
+              // if we find regular line-end or the end of the buffer.
+              aTokenStart = aCur + 1;
+              break;
+            }
+            mHaveMultiLine = false;
+            aTokenStart = aCur;
+          }
+          break; // from switch on (aChar)
+      }
+      break; // from switch on (mSpecialState)
+
+    // saw a \ character, so parse the character after that
+    case eParserSpecial_Escaped:
+      // probably want to start parsing at the next token
+      // other characters, like 'u' might override this
+      aTokenStart = aCur + 1;
+      mSpecialState = eParserSpecial_None;
+
+      switch (aChar) {
+        // the easy characters - \t, \n, and so forth
+        case 't':
+          mValue += char16_t('\t');
+          mMinLength = mValue.Length();
+          break;
+        case 'n':
+          mValue += char16_t('\n');
+          mMinLength = mValue.Length();
+          break;
+        case 'r':
+          mValue += char16_t('\r');
+          mMinLength = mValue.Length();
+          break;
+        case '\\':
+          mValue += char16_t('\\');
+          break;
+
+        // switch to unicode mode!
+        case 'u':
+        case 'U':
+          mSpecialState = eParserSpecial_Unicode;
+          mUnicodeValuesRead = 0;
+          mUnicodeValue = 0;
+          break;
+
+        // a \ immediately followed by a newline means we're going multiline
+        case '\r':
+        case '\n':
+          mHaveMultiLine = true;
+          mMultiLineCanSkipN = (aChar == '\r');
+          mSpecialState = eParserSpecial_None;
+          break;
+
+        default:
+          // don't recognize the character, so just append it
+          mValue += aChar;
+          break;
+      }
+      break;
+
+    // we're in the middle of parsing a 4-character unicode value
+    // like \u5f39
+    case eParserSpecial_Unicode:
+      if ('0' <= aChar && aChar <= '9') {
+        mUnicodeValue =
+          (mUnicodeValue << 4) | (aChar - '0');
+      } else if ('a' <= aChar && aChar <= 'f') {
+        mUnicodeValue =
+          (mUnicodeValue << 4) | (aChar - 'a' + 0x0a);
+      } else if ('A' <= aChar && aChar <= 'F') {
+        mUnicodeValue =
+          (mUnicodeValue << 4) | (aChar - 'A' + 0x0a);
+      } else {
+        // non-hex character. Append what we have, and move on.
+        mValue += mUnicodeValue;
+        mMinLength = mValue.Length();
+        mSpecialState = eParserSpecial_None;
+
+        // leave aTokenStart at this unknown character, so it gets appended
+        aTokenStart = aCur;
+
+        // ensure parsing this non-hex character again
+        return false;
+      }
+
+      if (++mUnicodeValuesRead >= 4) {
+        aTokenStart = aCur + 1;
+        mSpecialState = eParserSpecial_None;
+        mValue += mUnicodeValue;
+        mMinLength = mValue.Length();
+      }
+
+      break;
+  }
+
+  return true;
+}
+
+nsresult
+nsPropertiesParser::SegmentWriter(nsIUnicharInputStream* aStream,
+                                  void* aClosure,
+                                  const char16_t* aFromSegment,
+                                  uint32_t aToOffset,
+                                  uint32_t aCount,
+                                  uint32_t* aWriteCount)
+{
+  nsPropertiesParser* parser = static_cast<nsPropertiesParser*>(aClosure);
+  parser->ParseBuffer(aFromSegment, aCount);
+
+  *aWriteCount = aCount;
+  return NS_OK;
+}
+
+nsresult
+nsPropertiesParser::ParseBuffer(const char16_t* aBuffer,
+                                uint32_t aBufferLength)
+{
+  const char16_t* cur = aBuffer;
+  const char16_t* end = aBuffer + aBufferLength;
+
+  // points to the start/end of the current key or value
+  const char16_t* tokenStart = nullptr;
+
+  // if we're in the middle of parsing a key or value, make sure
+  // the current token points to the beginning of the current buffer
+  if (mState == eParserState_Key ||
+      mState == eParserState_Value) {
+    tokenStart = aBuffer;
+  }
+
+  nsAutoString oldValue;
+
+  while (cur != end) {
+
+    char16_t c = *cur;
+
+    switch (mState) {
+      case eParserState_AwaitingKey:
+        if (c == '#' || c == '!') {
+          EnterCommentState();
+        }
+
+        else if (!IsWhiteSpace(c)) {
+          // not a comment, not whitespace, we must have found a key!
+          EnterKeyState();
+          tokenStart = cur;
+        }
+        break;
+
+      case eParserState_Key:
+        if (c == '=' || c == ':') {
+          mKey += Substring(tokenStart, cur);
+          WaitForValue();
+        }
+        break;
+
+      case eParserState_AwaitingValue:
+        if (IsEOL(c)) {
+          // no value at all! mimic the normal value-ending
+          EnterValueState();
+          FinishValueState(oldValue);
+        }
+
+        // ignore white space leading up to the value
+        else if (!IsWhiteSpace(c)) {
+          tokenStart = cur;
+          EnterValueState();
+
+          // make sure to handle this first character
+          if (ParseValueCharacter(c, cur, tokenStart, oldValue)) {
+            cur++;
+          }
+          // If the character isn't consumed, don't do cur++ and parse
+          // the character again. This can happen f.e. for char 'X' in sequence
+          // "\u00X". This character can be control character and must be
+          // processed again.
+          continue;
+        }
+        break;
+
+      case eParserState_Value:
+        if (ParseValueCharacter(c, cur, tokenStart, oldValue)) {
+          cur++;
+        }
+        // See few lines above for reason of doing this
+        continue;
+
+      case eParserState_Comment:
+        // stay in this state till we hit EOL
+        if (c == '\r' || c == '\n') {
+          WaitForKey();
+        }
+        break;
+    }
+
+    // finally, advance to the next character
+    cur++;
+  }
+
+  // if we're still parsing the value and are in eParserSpecial_None, then
+  // append whatever we have..
+  if (mState == eParserState_Value && tokenStart &&
+      mSpecialState == eParserSpecial_None) {
+    mValue += Substring(tokenStart, cur);
+  }
+  // if we're still parsing the key, then append whatever we have..
+  else if (mState == eParserState_Key && tokenStart) {
+    mKey += Substring(tokenStart, cur);
+  }
+
+  return NS_OK;
+}
+
+nsPersistentProperties::nsPersistentProperties()
+  : mIn(nullptr)
+  , mTable(&property_HashTableOps, sizeof(PropertyTableEntry), 16)
+{
+  PL_INIT_ARENA_POOL(&mArena, "PersistentPropertyArena", 2048);
+}
+
+nsPersistentProperties::~nsPersistentProperties()
+{
+  PL_FinishArenaPool(&mArena);
+}
+
+nsresult
+nsPersistentProperties::Create(nsISupports* aOuter, REFNSIID aIID,
+                               void** aResult)
+{
+  if (aOuter) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+  RefPtr<nsPersistentProperties> props = new nsPersistentProperties();
+  return props->QueryInterface(aIID, aResult);
+}
+
+NS_IMPL_ISUPPORTS(nsPersistentProperties, nsIPersistentProperties, nsIProperties)
+
+NS_IMETHODIMP
+nsPersistentProperties::Load(nsIInputStream* aIn)
+{
+  nsresult rv = NS_NewUnicharInputStream(aIn, getter_AddRefs(mIn));
+
+  if (rv != NS_OK) {
+    NS_WARNING("Error creating UnicharInputStream");
+    return NS_ERROR_FAILURE;
+  }
+
+  nsPropertiesParser parser(this);
+
+  uint32_t nProcessed;
+  // If this 4096 is changed to some other value, make sure to adjust
+  // the bug121341.properties test file accordingly.
+  while (NS_SUCCEEDED(rv = mIn->ReadSegments(nsPropertiesParser::SegmentWriter,
+                                             &parser, 4096, &nProcessed)) &&
+         nProcessed != 0);
+  mIn = nullptr;
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // We may have an unprocessed value at this point
+  // if the last line did not have a proper line ending.
+  if (parser.GetState() == eParserState_Value) {
+    nsAutoString oldValue;
+    parser.FinishValueState(oldValue);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPersistentProperties::SetStringProperty(const nsACString& aKey,
+                                          const nsAString& aNewValue,
+                                          nsAString& aOldValue)
+{
+  const nsAFlatCString&  flatKey = PromiseFlatCString(aKey);
+  auto entry = static_cast<PropertyTableEntry*>
+                          (mTable.Add(flatKey.get()));
+
+  if (entry->mKey) {
+    aOldValue = entry->mValue;
+    NS_WARNING(nsPrintfCString("the property %s already exists",
+                               flatKey.get()).get());
+  } else {
+    aOldValue.Truncate();
+  }
+
+  entry->mKey = ArenaStrdup(flatKey, &mArena);
+  entry->mValue = ArenaStrdup(PromiseFlatString(aNewValue), &mArena);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPersistentProperties::Save(nsIOutputStream* aOut, const nsACString& aHeader)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsPersistentProperties::GetStringProperty(const nsACString& aKey,
+                                          nsAString& aValue)
+{
+  const nsAFlatCString&  flatKey = PromiseFlatCString(aKey);
+
+  auto entry = static_cast<PropertyTableEntry*>(mTable.Search(flatKey.get()));
+  if (!entry) {
+    return NS_ERROR_FAILURE;
+  }
+
+  aValue = entry->mValue;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPersistentProperties::Enumerate(nsISimpleEnumerator** aResult)
+{
+  nsCOMArray<nsIPropertyElement> props;
+
+  // We know the necessary size; we can avoid growing it while adding elements
+  props.SetCapacity(mTable.EntryCount());
+
+  // Step through hash entries populating a transient array
+  for (auto iter = mTable.Iter(); !iter.Done(); iter.Next()) {
+    auto entry = static_cast<PropertyTableEntry*>(iter.Get());
+
+    RefPtr<nsPropertyElement> element =
+      new nsPropertyElement(nsDependentCString(entry->mKey),
+                            nsDependentString(entry->mValue));
+
+    if (!props.AppendObject(element)) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+  }
+
+  return NS_NewArrayEnumerator(aResult, props);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// XXX Some day we'll unify the nsIPersistentProperties interface with
+// nsIProperties, but until now...
+
+NS_IMETHODIMP
+nsPersistentProperties::Get(const char* aProp, const nsIID& aUUID,
+                            void** aResult)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsPersistentProperties::Set(const char* aProp, nsISupports* value)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+NS_IMETHODIMP
+nsPersistentProperties::Undefine(const char* aProp)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsPersistentProperties::Has(const char* aProp, bool* aResult)
+{
+  *aResult = !!mTable.Search(aProp);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPersistentProperties::GetKeys(uint32_t* aCount, char*** aKeys)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// PropertyElement
+////////////////////////////////////////////////////////////////////////////////
+
+nsresult
+nsPropertyElement::Create(nsISupports* aOuter, REFNSIID aIID, void** aResult)
+{
+  if (aOuter) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+  RefPtr<nsPropertyElement> propElem = new nsPropertyElement();
+  return propElem->QueryInterface(aIID, aResult);
+}
+
+NS_IMPL_ISUPPORTS(nsPropertyElement, nsIPropertyElement)
+
+NS_IMETHODIMP
+nsPropertyElement::GetKey(nsACString& aReturnKey)
+{
+  aReturnKey = mKey;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPropertyElement::GetValue(nsAString& aReturnValue)
+{
+  aReturnValue = mValue;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPropertyElement::SetKey(const nsACString& aKey)
+{
+  mKey = aKey;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPropertyElement::SetValue(const nsAString& aValue)
+{
+  mValue = aValue;
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
diff --git a/xpcom/ds/nsPersistentProperties.h b/xpcom/ds/nsPersistentProperties.h
new file mode 100644
index 000000000..6c9e9cb51
--- /dev/null
+++ b/xpcom/ds/nsPersistentProperties.h
@@ -0,0 +1,67 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsPersistentProperties_h___
+#define nsPersistentProperties_h___
+
+#include "nsIPersistentProperties2.h"
+#include "PLDHashTable.h"
+#include "plarena.h"
+#include "nsString.h"
+#include "nsCOMPtr.h"
+#include "mozilla/Attributes.h"
+
+class nsIUnicharInputStream;
+
+class nsPersistentProperties final : public nsIPersistentProperties
+{
+public:
+  nsPersistentProperties();
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIPROPERTIES
+  NS_DECL_NSIPERSISTENTPROPERTIES
+
+  static MOZ_MUST_USE nsresult
+  Create(nsISupports* aOuter, REFNSIID aIID, void** aResult);
+
+private:
+  ~nsPersistentProperties();
+
+protected:
+  nsCOMPtr<nsIUnicharInputStream> mIn;
+
+  PLDHashTable mTable;
+  PLArenaPool mArena;
+};
+
+class nsPropertyElement final : public nsIPropertyElement
+{
+public:
+  nsPropertyElement()
+  {
+  }
+
+  nsPropertyElement(const nsACString& aKey, const nsAString& aValue)
+    : mKey(aKey)
+    , mValue(aValue)
+  {
+  }
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIPROPERTYELEMENT
+
+  static nsresult Create(nsISupports* aOuter, REFNSIID aIID, void** aResult);
+
+private:
+  ~nsPropertyElement() {}
+
+protected:
+  nsCString mKey;
+  nsString mValue;
+};
+
+#endif /* nsPersistentProperties_h___ */
diff --git a/xpcom/ds/nsProperties.cpp b/xpcom/ds/nsProperties.cpp
new file mode 100644
index 000000000..3a73ac7da
--- /dev/null
+++ b/xpcom/ds/nsProperties.cpp
@@ -0,0 +1,99 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsProperties.h"
+
+////////////////////////////////////////////////////////////////////////////////
+
+NS_IMPL_AGGREGATED(nsProperties)
+NS_INTERFACE_MAP_BEGIN_AGGREGATED(nsProperties)
+  NS_INTERFACE_MAP_ENTRY(nsIProperties)
+NS_INTERFACE_MAP_END
+
+NS_IMETHODIMP
+nsProperties::Get(const char* prop, const nsIID& uuid, void** result)
+{
+  if (NS_WARN_IF(!prop)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsCOMPtr<nsISupports> value;
+  if (!nsProperties_HashBase::Get(prop, getter_AddRefs(value))) {
+    return NS_ERROR_FAILURE;
+  }
+  return (value) ? value->QueryInterface(uuid, result) : NS_ERROR_NO_INTERFACE;
+}
+
+NS_IMETHODIMP
+nsProperties::Set(const char* prop, nsISupports* value)
+{
+  if (NS_WARN_IF(!prop)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  Put(prop, value);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProperties::Undefine(const char* prop)
+{
+  if (NS_WARN_IF(!prop)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsCOMPtr<nsISupports> value;
+  if (!nsProperties_HashBase::Get(prop, getter_AddRefs(value))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  Remove(prop);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProperties::Has(const char* prop, bool* result)
+{
+  if (NS_WARN_IF(!prop)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsCOMPtr<nsISupports> value;
+  *result = nsProperties_HashBase::Get(prop, getter_AddRefs(value));
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProperties::GetKeys(uint32_t* aCount, char*** aKeys)
+{
+  if (NS_WARN_IF(!aCount) || NS_WARN_IF(!aKeys)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  uint32_t count = Count();
+  char** keys = (char**)moz_xmalloc(count * sizeof(char*));
+  uint32_t j = 0;
+
+  for (auto iter = this->Iter(); !iter.Done(); iter.Next()) {
+    const char* key = iter.Key();
+    keys[j] = strdup(key);
+
+    if (!keys[j]) {
+      // Free 'em all
+      for (uint32_t i = 0; i < j; i++) {
+        free(keys[i]);
+      }
+      free(keys);
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    j++;
+  }
+
+  *aCount = count;
+  *aKeys = keys;
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
diff --git a/xpcom/ds/nsProperties.h b/xpcom/ds/nsProperties.h
new file mode 100644
index 000000000..6949017dd
--- /dev/null
+++ b/xpcom/ds/nsProperties.h
@@ -0,0 +1,39 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsProperties_h___
+#define nsProperties_h___
+
+#include "nsIProperties.h"
+#include "nsInterfaceHashtable.h"
+#include "nsHashKeys.h"
+#include "nsAgg.h"
+#include "mozilla/Attributes.h"
+
+#define NS_PROPERTIES_CID                            \
+{ /* 4de2bc90-b1bf-11d3-93b6-00104ba0fd40 */         \
+    0x4de2bc90,                                      \
+    0xb1bf,                                          \
+    0x11d3,                                          \
+    {0x93, 0xb6, 0x00, 0x10, 0x4b, 0xa0, 0xfd, 0x40} \
+}
+
+typedef nsInterfaceHashtable<nsCharPtrHashKey,
+                             nsISupports> nsProperties_HashBase;
+
+class nsProperties final
+  : public nsIProperties
+  , public nsProperties_HashBase
+{
+public:
+  NS_DECL_AGGREGATED
+  NS_DECL_NSIPROPERTIES
+
+  explicit nsProperties(nsISupports *aOuter) { NS_INIT_AGGREGATED(aOuter); }
+  ~nsProperties() {}
+};
+
+#endif /* nsProperties_h___ */
diff --git a/xpcom/ds/nsStaticAtom.h b/xpcom/ds/nsStaticAtom.h
new file mode 100644
index 000000000..7e31623db
--- /dev/null
+++ b/xpcom/ds/nsStaticAtom.h
@@ -0,0 +1,53 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsStaticAtom_h__
+#define nsStaticAtom_h__
+
+#include "nsIAtom.h"
+#include "nsStringBuffer.h"
+
+#define NS_STATIC_ATOM(buffer_name, atom_ptr) \
+  { (nsStringBuffer*) &buffer_name, atom_ptr }
+
+#define NS_STATIC_ATOM_BUFFER(buffer_name, str_data) \
+  static nsFakeStringBuffer<sizeof(str_data)> buffer_name = \
+    { 1, sizeof(str_data) * sizeof(char16_t), (u"" str_data) };
+
+/**
+ * Holds data used to initialize large number of atoms during startup. Use
+ * the above macros to initialize these structs. They should never be accessed
+ * directly other than from AtomTable.cpp
+ */
+struct nsStaticAtom
+{
+  // mStringBuffer points to the string buffer for a permanent atom, and is
+  // therefore safe as a non-owning reference.
+  nsStringBuffer* MOZ_NON_OWNING_REF mStringBuffer;
+  nsIAtom** mAtom;
+};
+
+/**
+ * This is a struct with the same binary layout as a nsStringBuffer.
+ */
+template<uint32_t size>
+struct nsFakeStringBuffer
+{
+  int32_t mRefCnt;
+  uint32_t mSize;
+  char16_t mStringData[size];
+};
+
+// Register an array of static atoms with the atom table
+template<uint32_t N>
+void
+NS_RegisterStaticAtoms(const nsStaticAtom (&aAtoms)[N])
+{
+  extern void RegisterStaticAtoms(const nsStaticAtom*, uint32_t aAtomCount);
+  RegisterStaticAtoms(aAtoms, N);
+}
+
+#endif
diff --git a/xpcom/ds/nsStaticNameTable.cpp b/xpcom/ds/nsStaticNameTable.cpp
new file mode 100644
index 000000000..26bd172a7
--- /dev/null
+++ b/xpcom/ds/nsStaticNameTable.cpp
@@ -0,0 +1,201 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Class to manage lookup of static names in a table. */
+
+#include "nsCRT.h"
+
+#include "nscore.h"
+#include "mozilla/HashFunctions.h"
+#include "nsISupportsImpl.h"
+
+#define PL_ARENA_CONST_ALIGN_MASK 3
+#include "nsStaticNameTable.h"
+
+using namespace mozilla;
+
+struct NameTableKey
+{
+  NameTableKey(const nsDependentCString aNameArray[],
+               const nsAFlatCString* aKeyStr)
+    : mNameArray(aNameArray)
+    , mIsUnichar(false)
+  {
+    mKeyStr.m1b = aKeyStr;
+  }
+
+  NameTableKey(const nsDependentCString aNameArray[],
+               const nsAFlatString* aKeyStr)
+    : mNameArray(aNameArray)
+    , mIsUnichar(true)
+  {
+    mKeyStr.m2b = aKeyStr;
+  }
+
+  const nsDependentCString* mNameArray;
+  union
+  {
+    const nsAFlatCString* m1b;
+    const nsAFlatString* m2b;
+  } mKeyStr;
+  bool mIsUnichar;
+};
+
+struct NameTableEntry : public PLDHashEntryHdr
+{
+  int32_t mIndex;
+};
+
+static bool
+matchNameKeysCaseInsensitive(const PLDHashEntryHdr* aHdr, const void* aVoidKey)
+{
+  auto entry = static_cast<const NameTableEntry*>(aHdr);
+  auto key = static_cast<const NameTableKey*>(aVoidKey);
+  const nsDependentCString* name = &key->mNameArray[entry->mIndex];
+
+  return key->mIsUnichar
+       ? key->mKeyStr.m2b->LowerCaseEqualsASCII(name->get(), name->Length())
+       : key->mKeyStr.m1b->LowerCaseEqualsASCII(name->get(), name->Length());
+}
+
+/*
+ * caseInsensitiveHashKey is just like PLDHashTable::HashStringKey except it
+ * uses (*s & ~0x20) instead of simply *s.  This means that "aFOO" and
+ * "afoo" and "aFoo" will all hash to the same thing.  It also means
+ * that some strings that aren't case-insensensitively equal will hash
+ * to the same value, but it's just a hash function so it doesn't
+ * matter.
+ */
+static PLDHashNumber
+caseInsensitiveStringHashKey(const void* aKey)
+{
+  PLDHashNumber h = 0;
+  const NameTableKey* tableKey = static_cast<const NameTableKey*>(aKey);
+  if (tableKey->mIsUnichar) {
+    for (const char16_t* s = tableKey->mKeyStr.m2b->get();
+         *s != '\0';
+         s++) {
+      h = AddToHash(h, *s & ~0x20);
+    }
+  } else {
+    for (const unsigned char* s = reinterpret_cast<const unsigned char*>(
+           tableKey->mKeyStr.m1b->get());
+         *s != '\0';
+         s++) {
+      h = AddToHash(h, *s & ~0x20);
+    }
+  }
+  return h;
+}
+
+static const struct PLDHashTableOps nametable_CaseInsensitiveHashTableOps = {
+  caseInsensitiveStringHashKey,
+  matchNameKeysCaseInsensitive,
+  PLDHashTable::MoveEntryStub,
+  PLDHashTable::ClearEntryStub,
+  nullptr,
+};
+
+nsStaticCaseInsensitiveNameTable::nsStaticCaseInsensitiveNameTable(
+    const char* const aNames[], int32_t aLength)
+  : mNameArray(nullptr)
+  , mNameTable(&nametable_CaseInsensitiveHashTableOps,
+               sizeof(NameTableEntry), aLength)
+  , mNullStr("")
+{
+  MOZ_COUNT_CTOR(nsStaticCaseInsensitiveNameTable);
+
+  MOZ_ASSERT(aNames, "null name table");
+  MOZ_ASSERT(aLength, "0 length");
+
+  mNameArray = (nsDependentCString*)
+    moz_xmalloc(aLength * sizeof(nsDependentCString));
+
+  for (int32_t index = 0; index < aLength; ++index) {
+    const char* raw = aNames[index];
+#ifdef DEBUG
+    {
+      // verify invariants of contents
+      nsAutoCString temp1(raw);
+      nsDependentCString temp2(raw);
+      ToLowerCase(temp1);
+      MOZ_ASSERT(temp1.Equals(temp2), "upper case char in table");
+      MOZ_ASSERT(nsCRT::IsAscii(raw),
+                 "non-ascii string in table -- "
+                 "case-insensitive matching won't work right");
+    }
+#endif
+    // use placement-new to initialize the string object
+    nsDependentCString* strPtr = &mNameArray[index];
+    new (strPtr) nsDependentCString(raw);
+
+    NameTableKey key(mNameArray, strPtr);
+
+    auto entry = static_cast<NameTableEntry*>(mNameTable.Add(&key, fallible));
+    if (!entry) {
+      continue;
+    }
+
+    // If the entry already exists it's unlikely but possible that its index is
+    // zero, in which case this assertion won't fail. But if the index is
+    // non-zero (highly likely) then it will fail. In other words, this
+    // assertion is likely but not guaranteed to detect if an entry is already
+    // used.
+    MOZ_ASSERT(entry->mIndex == 0, "Entry already exists!");
+
+    entry->mIndex = index;
+  }
+#ifdef DEBUG
+  mNameTable.MarkImmutable();
+#endif
+}
+
+nsStaticCaseInsensitiveNameTable::~nsStaticCaseInsensitiveNameTable()
+{
+  // manually call the destructor on placement-new'ed objects
+  for (uint32_t index = 0; index < mNameTable.EntryCount(); index++) {
+    mNameArray[index].~nsDependentCString();
+  }
+  free((void*)mNameArray);
+  MOZ_COUNT_DTOR(nsStaticCaseInsensitiveNameTable);
+}
+
+int32_t
+nsStaticCaseInsensitiveNameTable::Lookup(const nsACString& aName)
+{
+  NS_ASSERTION(mNameArray, "not inited");
+
+  const nsAFlatCString& str = PromiseFlatCString(aName);
+
+  NameTableKey key(mNameArray, &str);
+  auto entry = static_cast<NameTableEntry*>(mNameTable.Search(&key));
+
+  return entry ? entry->mIndex : nsStaticCaseInsensitiveNameTable::NOT_FOUND;
+}
+
+int32_t
+nsStaticCaseInsensitiveNameTable::Lookup(const nsAString& aName)
+{
+  NS_ASSERTION(mNameArray, "not inited");
+
+  const nsAFlatString& str = PromiseFlatString(aName);
+
+  NameTableKey key(mNameArray, &str);
+  auto entry = static_cast<NameTableEntry*>(mNameTable.Search(&key));
+
+  return entry ? entry->mIndex : nsStaticCaseInsensitiveNameTable::NOT_FOUND;
+}
+
+const nsAFlatCString&
+nsStaticCaseInsensitiveNameTable::GetStringValue(int32_t aIndex)
+{
+  NS_ASSERTION(mNameArray, "not inited");
+
+  if ((NOT_FOUND < aIndex) && ((uint32_t)aIndex < mNameTable.EntryCount())) {
+    return mNameArray[aIndex];
+  }
+  return mNullStr;
+}
diff --git a/xpcom/ds/nsStaticNameTable.h b/xpcom/ds/nsStaticNameTable.h
new file mode 100644
index 000000000..0b9df3039
--- /dev/null
+++ b/xpcom/ds/nsStaticNameTable.h
@@ -0,0 +1,49 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Classes to manage lookup of static names in a table. */
+
+#ifndef nsStaticNameTable_h___
+#define nsStaticNameTable_h___
+
+#include "PLDHashTable.h"
+#include "nsString.h"
+
+/* This class supports case insensitive lookup.
+ *
+ * It differs from atom tables:
+ * - It supports case insensitive lookup.
+ * - It has minimal footprint by not copying the string table.
+ * - It does no locking.
+ * - It returns zero based indexes and const nsCString& as required by its
+ *   callers in the parser.
+ * - It is not an xpcom interface - meant for fast lookup in static tables.
+ *
+ * ***REQUIREMENTS***
+ * - It *requires* that all entries in the table be lowercase only.
+ * - It *requires* that the table of strings be in memory that lives at least
+ *    as long as this table object - typically a static string array.
+ */
+
+class nsStaticCaseInsensitiveNameTable
+{
+public:
+  enum { NOT_FOUND = -1 };
+
+  int32_t          Lookup(const nsACString& aName);
+  int32_t          Lookup(const nsAString& aName);
+  const nsAFlatCString& GetStringValue(int32_t aIndex);
+
+  nsStaticCaseInsensitiveNameTable(const char* const aNames[], int32_t aLength);
+  ~nsStaticCaseInsensitiveNameTable();
+
+private:
+  nsDependentCString*   mNameArray;
+  PLDHashTable          mNameTable;
+  nsDependentCString    mNullStr;
+};
+
+#endif /* nsStaticNameTable_h___ */
diff --git a/xpcom/ds/nsStringEnumerator.cpp b/xpcom/ds/nsStringEnumerator.cpp
new file mode 100644
index 000000000..bdcd53e1a
--- /dev/null
+++ b/xpcom/ds/nsStringEnumerator.cpp
@@ -0,0 +1,262 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+#include "nsStringEnumerator.h"
+#include "nsISimpleEnumerator.h"
+#include "nsSupportsPrimitives.h"
+#include "mozilla/Attributes.h"
+#include "nsTArray.h"
+
+//
+// nsStringEnumerator
+//
+
+class nsStringEnumerator final
+  : public nsIStringEnumerator
+  , public nsIUTF8StringEnumerator
+  , public nsISimpleEnumerator
+{
+public:
+  nsStringEnumerator(const nsTArray<nsString>* aArray, bool aOwnsArray)
+    : mArray(aArray)
+    , mIndex(0)
+    , mOwnsArray(aOwnsArray)
+    , mIsUnicode(true)
+  {}
+
+  nsStringEnumerator(const nsTArray<nsCString>* aArray, bool aOwnsArray)
+    : mCArray(aArray)
+    , mIndex(0)
+    , mOwnsArray(aOwnsArray)
+    , mIsUnicode(false)
+  {}
+
+  nsStringEnumerator(const nsTArray<nsString>* aArray, nsISupports* aOwner)
+    : mArray(aArray)
+    , mIndex(0)
+    , mOwner(aOwner)
+    , mOwnsArray(false)
+    , mIsUnicode(true)
+  {}
+
+  nsStringEnumerator(const nsTArray<nsCString>* aArray, nsISupports* aOwner)
+    : mCArray(aArray)
+    , mIndex(0)
+    , mOwner(aOwner)
+    , mOwnsArray(false)
+    , mIsUnicode(false)
+  {}
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIUTF8STRINGENUMERATOR
+
+  // have to declare nsIStringEnumerator manually, because of
+  // overlapping method names
+  NS_IMETHOD GetNext(nsAString& aResult) override;
+  NS_DECL_NSISIMPLEENUMERATOR
+
+private:
+  ~nsStringEnumerator()
+  {
+    if (mOwnsArray) {
+      // const-casting is safe here, because the NS_New*
+      // constructors make sure mOwnsArray is consistent with
+      // the constness of the objects
+      if (mIsUnicode) {
+        delete const_cast<nsTArray<nsString>*>(mArray);
+      } else {
+        delete const_cast<nsTArray<nsCString>*>(mCArray);
+      }
+    }
+  }
+
+  union
+  {
+    const nsTArray<nsString>* mArray;
+    const nsTArray<nsCString>* mCArray;
+  };
+
+  inline uint32_t Count()
+  {
+    return mIsUnicode ? mArray->Length() : mCArray->Length();
+  }
+
+  uint32_t mIndex;
+
+  // the owner allows us to hold a strong reference to the object
+  // that owns the array. Having a non-null value in mOwner implies
+  // that mOwnsArray is false, because we rely on the real owner
+  // to release the array
+  nsCOMPtr<nsISupports> mOwner;
+  bool mOwnsArray;
+  bool mIsUnicode;
+};
+
+NS_IMPL_ISUPPORTS(nsStringEnumerator,
+                  nsIStringEnumerator,
+                  nsIUTF8StringEnumerator,
+                  nsISimpleEnumerator)
+
+NS_IMETHODIMP
+nsStringEnumerator::HasMore(bool* aResult)
+{
+  *aResult = mIndex < Count();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStringEnumerator::HasMoreElements(bool* aResult)
+{
+  return HasMore(aResult);
+}
+
+NS_IMETHODIMP
+nsStringEnumerator::GetNext(nsISupports** aResult)
+{
+  if (mIsUnicode) {
+    nsSupportsString* stringImpl = new nsSupportsString();
+    if (!stringImpl) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    stringImpl->SetData(mArray->ElementAt(mIndex++));
+    *aResult = stringImpl;
+  } else {
+    nsSupportsCString* cstringImpl = new nsSupportsCString();
+    if (!cstringImpl) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    cstringImpl->SetData(mCArray->ElementAt(mIndex++));
+    *aResult = cstringImpl;
+  }
+  NS_ADDREF(*aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStringEnumerator::GetNext(nsAString& aResult)
+{
+  if (NS_WARN_IF(mIndex >= Count())) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (mIsUnicode) {
+    aResult = mArray->ElementAt(mIndex++);
+  } else {
+    CopyUTF8toUTF16(mCArray->ElementAt(mIndex++), aResult);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStringEnumerator::GetNext(nsACString& aResult)
+{
+  if (NS_WARN_IF(mIndex >= Count())) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (mIsUnicode) {
+    CopyUTF16toUTF8(mArray->ElementAt(mIndex++), aResult);
+  } else {
+    aResult = mCArray->ElementAt(mIndex++);
+  }
+
+  return NS_OK;
+}
+
+template<class T>
+static inline nsresult
+StringEnumeratorTail(T** aResult)
+{
+  if (!*aResult) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  NS_ADDREF(*aResult);
+  return NS_OK;
+}
+
+//
+// constructors
+//
+
+nsresult
+NS_NewStringEnumerator(nsIStringEnumerator** aResult,
+                       const nsTArray<nsString>* aArray, nsISupports* aOwner)
+{
+  if (NS_WARN_IF(!aResult) || NS_WARN_IF(!aArray)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  *aResult = new nsStringEnumerator(aArray, aOwner);
+  return StringEnumeratorTail(aResult);
+}
+
+
+nsresult
+NS_NewUTF8StringEnumerator(nsIUTF8StringEnumerator** aResult,
+                           const nsTArray<nsCString>* aArray,
+                           nsISupports* aOwner)
+{
+  if (NS_WARN_IF(!aResult) || NS_WARN_IF(!aArray)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  *aResult = new nsStringEnumerator(aArray, aOwner);
+  return StringEnumeratorTail(aResult);
+}
+
+nsresult
+NS_NewAdoptingStringEnumerator(nsIStringEnumerator** aResult,
+                               nsTArray<nsString>* aArray)
+{
+  if (NS_WARN_IF(!aResult) || NS_WARN_IF(!aArray)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  *aResult = new nsStringEnumerator(aArray, true);
+  return StringEnumeratorTail(aResult);
+}
+
+nsresult
+NS_NewAdoptingUTF8StringEnumerator(nsIUTF8StringEnumerator** aResult,
+                                   nsTArray<nsCString>* aArray)
+{
+  if (NS_WARN_IF(!aResult) || NS_WARN_IF(!aArray)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  *aResult = new nsStringEnumerator(aArray, true);
+  return StringEnumeratorTail(aResult);
+}
+
+// const ones internally just forward to the non-const equivalents
+nsresult
+NS_NewStringEnumerator(nsIStringEnumerator** aResult,
+                       const nsTArray<nsString>* aArray)
+{
+  if (NS_WARN_IF(!aResult) || NS_WARN_IF(!aArray)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  *aResult = new nsStringEnumerator(aArray, false);
+  return StringEnumeratorTail(aResult);
+}
+
+nsresult
+NS_NewUTF8StringEnumerator(nsIUTF8StringEnumerator** aResult,
+                           const nsTArray<nsCString>* aArray)
+{
+  if (NS_WARN_IF(!aResult) || NS_WARN_IF(!aArray)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  *aResult = new nsStringEnumerator(aArray, false);
+  return StringEnumeratorTail(aResult);
+}
+
diff --git a/xpcom/ds/nsStringEnumerator.h b/xpcom/ds/nsStringEnumerator.h
new file mode 100644
index 000000000..226afd7f4
--- /dev/null
+++ b/xpcom/ds/nsStringEnumerator.h
@@ -0,0 +1,91 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIStringEnumerator.h"
+#include "nsStringFwd.h"
+#include "nsTArrayForwardDeclare.h"
+
+// nsIStringEnumerator/nsIUTF8StringEnumerator implementations
+//
+// Currently all implementations support both interfaces. The
+// constructors below provide the most common interface for the given
+// type (i.e. nsIStringEnumerator for char16_t* strings, and so
+// forth) but any resulting enumerators can be queried to the other
+// type. Internally, the enumerators will hold onto the type that was
+// passed in and do conversion if GetNext() for the other type of
+// string is called.
+
+// There are a few different types of enumerators:
+
+//
+// These enumerators hold a pointer to the array. Be careful
+// because modifying the array may confuse the iterator, especially if
+// you insert or remove elements in the middle of the array.
+//
+
+// The non-adopting enumerator requires that the array sticks around
+// at least as long as the enumerator does. These are for constant
+// string arrays that the enumerator does not own, this could be used
+// in VERY specialized cases such as when the provider KNOWS that the
+// string enumerator will be consumed immediately, or will at least
+// outlast the array.
+// For example:
+//
+// nsTArray<nsCString> array;
+// array.AppendCString("abc");
+// array.AppendCString("def");
+// NS_NewStringEnumerator(&enumerator, &array, true);
+//
+// // call some internal method which iterates the enumerator
+// InternalMethod(enumerator);
+// NS_RELEASE(enumerator);
+//
+MOZ_MUST_USE nsresult
+NS_NewStringEnumerator(nsIStringEnumerator** aResult,
+                       const nsTArray<nsString>* aArray,
+                       nsISupports* aOwner);
+MOZ_MUST_USE nsresult
+NS_NewUTF8StringEnumerator(nsIUTF8StringEnumerator** aResult,
+                           const nsTArray<nsCString>* aArray);
+
+MOZ_MUST_USE nsresult
+NS_NewStringEnumerator(nsIStringEnumerator** aResult,
+                       const nsTArray<nsString>* aArray);
+
+// Adopting string enumerators assume ownership of the array and will
+// call |operator delete| on the array when the enumerator is destroyed
+// this is useful when the provider creates an array solely for the
+// purpose of creating the enumerator.
+// For example:
+//
+// nsTArray<nsCString>* array = new nsTArray<nsCString>;
+// array->AppendString("abcd");
+// NS_NewAdoptingStringEnumerator(&result, array);
+MOZ_MUST_USE nsresult
+NS_NewAdoptingStringEnumerator(nsIStringEnumerator** aResult,
+                               nsTArray<nsString>* aArray);
+
+MOZ_MUST_USE nsresult
+NS_NewAdoptingUTF8StringEnumerator(nsIUTF8StringEnumerator** aResult,
+                                   nsTArray<nsCString>* aArray);
+
+
+// these versions take a refcounted "owner" which will be addreffed
+// when the enumerator is created, and destroyed when the enumerator
+// is released. This allows providers to give non-owning pointers to
+// ns*StringArray member variables without worrying about lifetime
+// issues
+// For example:
+//
+// nsresult MyClass::Enumerate(nsIUTF8StringEnumerator** aResult) {
+//     mCategoryList->AppendString("abcd");
+//     return NS_NewStringEnumerator(aResult, mCategoryList, this);
+// }
+//
+MOZ_MUST_USE nsresult
+NS_NewUTF8StringEnumerator(nsIUTF8StringEnumerator** aResult,
+                           const nsTArray<nsCString>* aArray,
+                           nsISupports* aOwner);
diff --git a/xpcom/ds/nsSupportsArray.cpp b/xpcom/ds/nsSupportsArray.cpp
new file mode 100644
index 000000000..67de8ae16
--- /dev/null
+++ b/xpcom/ds/nsSupportsArray.cpp
@@ -0,0 +1,264 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdint.h>
+#include <string.h>
+
+#include "nsArrayEnumerator.h"
+#include "nsIObjectInputStream.h"
+#include "nsIObjectOutputStream.h"
+#include "nsSupportsArray.h"
+#include "nsSupportsArrayEnumerator.h"
+
+// Disable deprecation warnings generated by nsISupportsArray and associated
+// classes.
+#if defined(__GNUC__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+#elif defined(_MSC_VER)
+#pragma warning (push)
+#pragma warning (disable : 4996)
+#endif
+
+nsresult
+nsQueryElementAt::operator()(const nsIID& aIID, void** aResult) const
+{
+  nsresult status =
+    mCollection ? mCollection->QueryElementAt(mIndex, aIID, aResult) :
+                  NS_ERROR_NULL_POINTER;
+
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+
+  return status;
+}
+
+nsSupportsArray::nsSupportsArray()
+{
+}
+
+nsSupportsArray::~nsSupportsArray()
+{
+  Clear();
+}
+
+nsresult
+nsSupportsArray::Create(nsISupports* aOuter, REFNSIID aIID, void** aResult)
+{
+  if (aOuter) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+
+  nsCOMPtr<nsISupportsArray> it = new nsSupportsArray();
+
+  return it->QueryInterface(aIID, aResult);
+}
+
+NS_IMPL_ISUPPORTS(nsSupportsArray, nsIArray, nsISupportsArray, nsICollection,
+                  nsISerializable)
+
+NS_IMETHODIMP
+nsSupportsArray::Read(nsIObjectInputStream* aStream)
+{
+  nsresult rv;
+
+  uint32_t newArraySize;
+  rv = aStream->Read32(&newArraySize);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  uint32_t count;
+  rv = aStream->Read32(&count);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  NS_ASSERTION(count <= newArraySize, "overlarge mCount!");
+  if (count > newArraySize) {
+    count = newArraySize;
+  }
+
+  // Don't clear out our array until we know we have enough space for the new
+  // one and have successfully copied everything out of the stream.
+  nsCOMArray<nsISupports> tmp;
+  tmp.SetCapacity(newArraySize);
+  tmp.SetCount(count);
+
+  auto elems = tmp.Elements();
+  for (uint32_t i = 0; i < count; i++) {
+    rv = aStream->ReadObject(true, &elems[i]);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+  }
+
+  // Now clear out existing refs and replace with the new array.
+  mArray.Clear();
+  mArray.SwapElements(tmp);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsArray::Write(nsIObjectOutputStream* aStream)
+{
+  nsresult rv;
+
+  rv = aStream->Write32(mArray.Capacity());
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  rv = aStream->Write32(mArray.Length());
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  for (size_t i = 0; i < mArray.Length(); i++) {
+    rv = aStream->WriteObject(mArray[i], true);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsArray::GetElementAt(uint32_t aIndex, nsISupports** aOutPtr)
+{
+  nsCOMPtr<nsISupports> elm = mArray.SafeElementAt(aIndex);
+  elm.forget(aOutPtr);
+  return NS_OK;
+}
+
+NS_IMETHODIMP_(int32_t)
+nsSupportsArray::IndexOf(const nsISupports* aPossibleElement)
+{
+  // nsCOMArray takes a non-const param, but it just passes through to
+  // nsTArray which takes a const param.
+  return mArray.IndexOf(const_cast<nsISupports*>(aPossibleElement));
+}
+
+NS_IMETHODIMP_(bool)
+nsSupportsArray::InsertElementAt(nsISupports* aElement, uint32_t aIndex)
+{
+  return mArray.InsertObjectAt(aElement, aIndex);
+}
+
+NS_IMETHODIMP_(bool)
+nsSupportsArray::ReplaceElementAt(nsISupports* aElement, uint32_t aIndex)
+{
+  // nsCOMArray::ReplaceObjectAt will grow the array if necessary. Instead
+  // we do the bounds check and only replace if it's in range.
+  if (aIndex < mArray.Length()) {
+    mArray.ReplaceElementAt(aIndex, aElement);
+    return true;
+  }
+  return false;
+}
+
+NS_IMETHODIMP_(bool)
+nsSupportsArray::RemoveElementAt(uint32_t aIndex)
+{
+  return mArray.RemoveObjectAt(aIndex);
+}
+
+NS_IMETHODIMP
+nsSupportsArray::RemoveElement(nsISupports* aElement)
+{
+  return mArray.RemoveObject(aElement) ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsSupportsArray::Clear(void)
+{
+  mArray.Clear();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsArray::DeprecatedEnumerate(nsIEnumerator** aResult)
+{
+  RefPtr<nsSupportsArrayEnumerator> e = new nsSupportsArrayEnumerator(this);
+  e.forget(aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsArray::Clone(nsISupportsArray** aResult)
+{
+  nsCOMPtr<nsISupportsArray> newArray;
+  nsresult rv = NS_NewISupportsArray(getter_AddRefs(newArray));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  for (size_t i = 0; i < mArray.Length(); i++) {
+    // AppendElement does an odd cast of bool to nsresult, we just cast back
+    // here.
+    if (!(bool)newArray->AppendElement(mArray[i])) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+  }
+
+  newArray.forget(aResult);
+  return NS_OK;
+}
+
+nsresult
+NS_NewISupportsArray(nsISupportsArray** aInstancePtrResult)
+{
+  nsresult rv;
+  rv = nsSupportsArray::Create(nullptr, NS_GET_IID(nsISupportsArray),
+                               (void**)aInstancePtrResult);
+  return rv;
+}
+
+/**
+ * nsIArray adapters.
+ */
+NS_IMETHODIMP
+nsSupportsArray::GetLength(uint32_t* aLength) {
+  return Count(aLength);
+}
+
+NS_IMETHODIMP
+nsSupportsArray::QueryElementAt(uint32_t aIndex, const nsIID& aIID, void** aResult)
+{
+  nsISupports* element = mArray.SafeElementAt(aIndex);
+  if (element) {
+    return element->QueryInterface(aIID, aResult);
+  }
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsSupportsArray::IndexOf(uint32_t aStartIndex, nsISupports* aElement, uint32_t* aResult)
+{
+  int32_t idx = mArray.IndexOf(aElement, aStartIndex);
+  if (idx < 0) {
+    return NS_ERROR_FAILURE;
+  }
+
+  *aResult = static_cast<uint32_t>(idx);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsArray::Enumerate(nsISimpleEnumerator** aResult)
+{
+  return NS_NewArrayEnumerator(aResult, this);
+}
+
+#if defined(__GNUC__)
+#pragma GCC diagnostic pop
+#elif defined(_MSC_VER)
+#pragma warning (pop)
+#endif
+
diff --git a/xpcom/ds/nsSupportsArray.h b/xpcom/ds/nsSupportsArray.h
new file mode 100644
index 000000000..eed611104
--- /dev/null
+++ b/xpcom/ds/nsSupportsArray.h
@@ -0,0 +1,107 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSupportsArray_h__
+#define nsSupportsArray_h__
+
+#include "nsIArray.h"
+#include "nsCOMArray.h"
+#include "mozilla/Attributes.h"
+
+
+// Disable deprecation warnings generated by nsISupportsArray and associated
+// classes.
+#if defined(__GNUC__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+#elif defined(_MSC_VER)
+#pragma warning (push)
+#pragma warning (disable : 4996)
+#endif
+
+#include "nsISupportsArray.h"
+
+class nsSupportsArray final : public nsISupportsArray,
+                              public nsIArray
+{
+  ~nsSupportsArray(void); // nonvirtual since we're not subclassed
+
+public:
+  nsSupportsArray(void);
+
+  static MOZ_MUST_USE nsresult
+  Create(nsISupports* aOuter, REFNSIID aIID, void** aResult);
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  NS_DECL_NSISERIALIZABLE
+
+  // nsICollection methods:
+  NS_IMETHOD Count(uint32_t* aResult) override
+  {
+    *aResult = mArray.Length();
+    return NS_OK;
+  }
+  NS_IMETHOD GetElementAt(uint32_t aIndex, nsISupports** aResult) override;
+  MOZ_MUST_USE NS_IMETHOD
+  SetElementAt(uint32_t aIndex, nsISupports* aValue) override
+  {
+    return ReplaceElementAt(aValue, aIndex) ? NS_OK : NS_ERROR_FAILURE;
+  }
+  MOZ_MUST_USE NS_IMETHOD AppendElement(nsISupports* aElement) override
+  {
+    // XXX Invalid cast of bool to nsresult (bug 778110)
+    return (nsresult)InsertElementAt(aElement, mArray.Length())/* ? NS_OK : NS_ERROR_FAILURE*/;
+  }
+  // XXX this is badly named - should be RemoveFirstElement
+  MOZ_MUST_USE NS_IMETHOD RemoveElement(nsISupports* aElement) override;
+  NS_IMETHOD DeprecatedEnumerate(nsIEnumerator** aResult) override;
+  NS_IMETHOD Clear(void) override;
+
+  // nsISupportsArray methods:
+  NS_IMETHOD_(int32_t) IndexOf(const nsISupports* aPossibleElement) override;
+
+  NS_IMETHOD GetIndexOf(nsISupports* aPossibleElement, int32_t* aResult) override
+  {
+    *aResult = IndexOf(aPossibleElement);
+    return NS_OK;
+  }
+
+  MOZ_MUST_USE NS_IMETHOD_(bool)
+  InsertElementAt(nsISupports* aElement, uint32_t aIndex) override;
+
+  MOZ_MUST_USE NS_IMETHOD_(bool)
+  ReplaceElementAt(nsISupports* aElement, uint32_t aIndex) override;
+
+  MOZ_MUST_USE NS_IMETHOD_(bool)
+  RemoveElementAt(uint32_t aIndex) override;
+
+  MOZ_MUST_USE NS_IMETHOD DeleteElementAt(uint32_t aIndex) override
+  {
+    return (RemoveElementAt(aIndex) ? NS_OK : NS_ERROR_FAILURE);
+  }
+
+  MOZ_MUST_USE NS_IMETHOD Clone(nsISupportsArray** aResult) override;
+
+  /**
+   * nsIArray adapters.
+   */
+  NS_DECL_NSIARRAY
+
+private:
+  // Copy constructors are not allowed
+  explicit nsSupportsArray(const nsISupportsArray& aOther);
+
+  nsCOMArray<nsISupports> mArray;
+};
+
+#if defined(__GNUC__)
+#pragma GCC diagnostic pop
+#elif defined(_MSC_VER)
+#pragma warning (pop)
+#endif
+
+#endif // nsSupportsArray_h__
diff --git a/xpcom/ds/nsSupportsArrayEnumerator.cpp b/xpcom/ds/nsSupportsArrayEnumerator.cpp
new file mode 100644
index 000000000..3eb6a7a58
--- /dev/null
+++ b/xpcom/ds/nsSupportsArrayEnumerator.cpp
@@ -0,0 +1,131 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsSupportsArrayEnumerator.h"
+
+// Disable deprecation warnings generated by nsISupportsArray and associated
+// classes.
+#if defined(__GNUC__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+#elif defined(_MSC_VER)
+#pragma warning (push)
+#pragma warning (disable : 4996)
+#endif
+
+#include "nsISupportsArray.h"
+
+nsSupportsArrayEnumerator::nsSupportsArrayEnumerator(nsISupportsArray* array)
+  : mArray(array)
+  , mCursor(0)
+{
+  NS_ASSERTION(array, "null array");
+}
+
+nsSupportsArrayEnumerator::~nsSupportsArrayEnumerator()
+{
+}
+
+NS_IMPL_ISUPPORTS(nsSupportsArrayEnumerator, nsIBidirectionalEnumerator,
+                  nsIEnumerator)
+
+NS_IMETHODIMP
+nsSupportsArrayEnumerator::First()
+{
+  mCursor = 0;
+  uint32_t cnt;
+  nsresult rv = mArray->Count(&cnt);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  int32_t end = (int32_t)cnt;
+  if (mCursor < end) {
+    return NS_OK;
+  } else {
+    return NS_ERROR_FAILURE;
+  }
+}
+
+NS_IMETHODIMP
+nsSupportsArrayEnumerator::Next()
+{
+  uint32_t cnt;
+  nsresult rv = mArray->Count(&cnt);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  int32_t end = (int32_t)cnt;
+  if (mCursor < end) { // don't count upward forever
+    mCursor++;
+  }
+  if (mCursor < end) {
+    return NS_OK;
+  } else {
+    return NS_ERROR_FAILURE;
+  }
+}
+
+NS_IMETHODIMP
+nsSupportsArrayEnumerator::CurrentItem(nsISupports** aItem)
+{
+  NS_ASSERTION(aItem, "null out parameter");
+  uint32_t cnt;
+  nsresult rv = mArray->Count(&cnt);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (mCursor >= 0 && mCursor < (int32_t)cnt) {
+    return mArray->GetElementAt(mCursor, aItem);
+  }
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsSupportsArrayEnumerator::IsDone()
+{
+  uint32_t cnt;
+  nsresult rv = mArray->Count(&cnt);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  // XXX This is completely incompatible with the meaning of nsresult.
+  // NS_ENUMERATOR_FALSE is defined to be 1.  (bug 778111)
+  return (mCursor >= 0 && mCursor < (int32_t)cnt)
+    ? (nsresult)NS_ENUMERATOR_FALSE : NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+NS_IMETHODIMP
+nsSupportsArrayEnumerator::Last()
+{
+  uint32_t cnt;
+  nsresult rv = mArray->Count(&cnt);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  mCursor = cnt - 1;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsArrayEnumerator::Prev()
+{
+  if (mCursor >= 0) {
+    --mCursor;
+  }
+  if (mCursor >= 0) {
+    return NS_OK;
+  } else {
+    return NS_ERROR_FAILURE;
+  }
+}
+
+#if defined(__GNUC__)
+#pragma GCC diagnostic pop
+#elif defined(_MSC_VER)
+#pragma warning (pop)
+#endif
diff --git a/xpcom/ds/nsSupportsArrayEnumerator.h b/xpcom/ds/nsSupportsArrayEnumerator.h
new file mode 100644
index 000000000..bd316d6b9
--- /dev/null
+++ b/xpcom/ds/nsSupportsArrayEnumerator.h
@@ -0,0 +1,56 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSupportsArrayEnumerator_h___
+#define nsSupportsArrayEnumerator_h___
+
+#include "nsCOMPtr.h"
+#include "mozilla/Attributes.h"
+
+// Disable deprecation warnings generated by nsISupportsArray and associated
+// classes.
+#if defined(__GNUC__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+#elif defined(_MSC_VER)
+#pragma warning (push)
+#pragma warning (disable : 4996)
+#endif
+
+#include "nsIEnumerator.h"
+
+class nsISupportsArray;
+
+class nsSupportsArrayEnumerator final : public nsIBidirectionalEnumerator
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  explicit nsSupportsArrayEnumerator(nsISupportsArray* aArray);
+
+  // nsIEnumerator methods:
+  NS_DECL_NSIENUMERATOR
+
+  // nsIBidirectionalEnumerator methods:
+  NS_DECL_NSIBIDIRECTIONALENUMERATOR
+
+private:
+  ~nsSupportsArrayEnumerator();
+
+protected:
+  nsCOMPtr<nsISupportsArray> mArray;
+  int32_t               mCursor;
+
+};
+
+#if defined(__GNUC__)
+#pragma GCC diagnostic pop
+#elif defined(_MSC_VER)
+#pragma warning (pop)
+#endif
+
+#endif // __nsSupportsArrayEnumerator_h
+
diff --git a/xpcom/ds/nsSupportsPrimitives.cpp b/xpcom/ds/nsSupportsPrimitives.cpp
new file mode 100644
index 000000000..aa929b9de
--- /dev/null
+++ b/xpcom/ds/nsSupportsPrimitives.cpp
@@ -0,0 +1,849 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsSupportsPrimitives.h"
+#include "nsMemory.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/IntegerPrintfMacros.h"
+#include "mozilla/Sprintf.h"
+#include <algorithm>
+
+template<typename T>
+static char*
+DataToString(const char* aFormat, T aData)
+{
+  static const int size = 32;
+  char buf[size];
+
+  int len = SprintfLiteral(buf, aFormat, aData);
+  MOZ_ASSERT(len >= 0);
+
+  return static_cast<char*>(nsMemory::Clone(buf, std::min(len + 1, size) *
+                                                 sizeof(char)));
+}
+
+/***************************************************************************/
+
+NS_IMPL_ISUPPORTS(nsSupportsID, nsISupportsID, nsISupportsPrimitive)
+
+nsSupportsID::nsSupportsID()
+  : mData(nullptr)
+{
+}
+
+NS_IMETHODIMP
+nsSupportsID::GetType(uint16_t* aType)
+{
+  NS_ASSERTION(aType, "Bad pointer");
+  *aType = TYPE_ID;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsID::GetData(nsID** aData)
+{
+  NS_ASSERTION(aData, "Bad pointer");
+
+  if (mData) {
+    *aData = static_cast<nsID*>(nsMemory::Clone(mData, sizeof(nsID)));
+  } else {
+    *aData = nullptr;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsID::SetData(const nsID* aData)
+{
+  if (mData) {
+    free(mData);
+  }
+
+  if (aData) {
+    mData = static_cast<nsID*>(nsMemory::Clone(aData, sizeof(nsID)));
+  } else {
+    mData = nullptr;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsID::ToString(char** aResult)
+{
+  NS_ASSERTION(aResult, "Bad pointer");
+
+  if (mData) {
+    *aResult = mData->ToString();
+  } else {
+    static const char nullStr[] = "null";
+    *aResult = static_cast<char*>(nsMemory::Clone(nullStr, sizeof(nullStr)));
+  }
+
+  return NS_OK;
+}
+
+/*****************************************************************************
+ * nsSupportsCString
+ *****************************************************************************/
+
+NS_IMPL_ISUPPORTS(nsSupportsCString, nsISupportsCString,
+                  nsISupportsPrimitive)
+
+NS_IMETHODIMP
+nsSupportsCString::GetType(uint16_t* aType)
+{
+  NS_ASSERTION(aType, "Bad pointer");
+  *aType = TYPE_CSTRING;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsCString::GetData(nsACString& aData)
+{
+  aData = mData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsCString::ToString(char** aResult)
+{
+  *aResult = ToNewCString(mData);
+  if (!*aResult) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsCString::SetData(const nsACString& aData)
+{
+  bool ok = mData.Assign(aData, mozilla::fallible);
+  if (!ok) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  return NS_OK;
+}
+
+/*****************************************************************************
+ * nsSupportsString
+ *****************************************************************************/
+
+NS_IMPL_ISUPPORTS(nsSupportsString, nsISupportsString,
+                  nsISupportsPrimitive)
+
+NS_IMETHODIMP
+nsSupportsString::GetType(uint16_t* aType)
+{
+  NS_ASSERTION(aType, "Bad pointer");
+  *aType = TYPE_STRING;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsString::GetData(nsAString& aData)
+{
+  aData = mData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsString::ToString(char16_t** aResult)
+{
+  *aResult = ToNewUnicode(mData);
+  if (!*aResult) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsString::SetData(const nsAString& aData)
+{
+  bool ok = mData.Assign(aData, mozilla::fallible);
+  if (!ok) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  return NS_OK;
+}
+
+/***************************************************************************/
+
+NS_IMPL_ISUPPORTS(nsSupportsPRBool, nsISupportsPRBool,
+                  nsISupportsPrimitive)
+
+nsSupportsPRBool::nsSupportsPRBool()
+  : mData(false)
+{
+}
+
+NS_IMETHODIMP
+nsSupportsPRBool::GetType(uint16_t* aType)
+{
+  NS_ASSERTION(aType, "Bad pointer");
+  *aType = TYPE_PRBOOL;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRBool::GetData(bool* aData)
+{
+  NS_ASSERTION(aData, "Bad pointer");
+  *aData = mData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRBool::SetData(bool aData)
+{
+  mData = aData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRBool::ToString(char** aResult)
+{
+  NS_ASSERTION(aResult, "Bad pointer");
+  const char* str = mData ? "true" : "false";
+  *aResult = static_cast<char*>(nsMemory::Clone(str, (strlen(str) + 1) *
+                                                     sizeof(char)));
+  return NS_OK;
+}
+
+/***************************************************************************/
+
+NS_IMPL_ISUPPORTS(nsSupportsPRUint8, nsISupportsPRUint8,
+                  nsISupportsPrimitive)
+
+nsSupportsPRUint8::nsSupportsPRUint8()
+  : mData(0)
+{
+}
+
+NS_IMETHODIMP
+nsSupportsPRUint8::GetType(uint16_t* aType)
+{
+  NS_ASSERTION(aType, "Bad pointer");
+  *aType = TYPE_PRUINT8;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRUint8::GetData(uint8_t* aData)
+{
+  NS_ASSERTION(aData, "Bad pointer");
+  *aData = mData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRUint8::SetData(uint8_t aData)
+{
+  mData = aData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRUint8::ToString(char** aResult)
+{
+  NS_ASSERTION(aResult, "Bad pointer");
+  *aResult = DataToString("%u", static_cast<unsigned int>(mData));
+  return NS_OK;
+}
+
+/***************************************************************************/
+
+NS_IMPL_ISUPPORTS(nsSupportsPRUint16, nsISupportsPRUint16,
+                  nsISupportsPrimitive)
+
+nsSupportsPRUint16::nsSupportsPRUint16()
+  : mData(0)
+{
+}
+
+NS_IMETHODIMP
+nsSupportsPRUint16::GetType(uint16_t* aType)
+{
+  NS_ASSERTION(aType, "Bad pointer");
+  *aType = TYPE_PRUINT16;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRUint16::GetData(uint16_t* aData)
+{
+  NS_ASSERTION(aData, "Bad pointer");
+  *aData = mData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRUint16::SetData(uint16_t aData)
+{
+  mData = aData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRUint16::ToString(char** aResult)
+{
+  NS_ASSERTION(aResult, "Bad pointer");
+  *aResult = DataToString("%u", static_cast<unsigned int>(mData));
+  return NS_OK;
+}
+
+/***************************************************************************/
+
+NS_IMPL_ISUPPORTS(nsSupportsPRUint32, nsISupportsPRUint32,
+                  nsISupportsPrimitive)
+
+nsSupportsPRUint32::nsSupportsPRUint32()
+  : mData(0)
+{
+}
+
+NS_IMETHODIMP
+nsSupportsPRUint32::GetType(uint16_t* aType)
+{
+  NS_ASSERTION(aType, "Bad pointer");
+  *aType = TYPE_PRUINT32;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRUint32::GetData(uint32_t* aData)
+{
+  NS_ASSERTION(aData, "Bad pointer");
+  *aData = mData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRUint32::SetData(uint32_t aData)
+{
+  mData = aData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRUint32::ToString(char** aResult)
+{
+  NS_ASSERTION(aResult, "Bad pointer");
+  *aResult = DataToString("%u", mData);
+  return NS_OK;
+}
+
+/***************************************************************************/
+
+NS_IMPL_ISUPPORTS(nsSupportsPRUint64, nsISupportsPRUint64,
+                  nsISupportsPrimitive)
+
+nsSupportsPRUint64::nsSupportsPRUint64()
+  : mData(0)
+{
+}
+
+NS_IMETHODIMP
+nsSupportsPRUint64::GetType(uint16_t* aType)
+{
+  NS_ASSERTION(aType, "Bad pointer");
+  *aType = TYPE_PRUINT64;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRUint64::GetData(uint64_t* aData)
+{
+  NS_ASSERTION(aData, "Bad pointer");
+  *aData = mData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRUint64::SetData(uint64_t aData)
+{
+  mData = aData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRUint64::ToString(char** aResult)
+{
+  NS_ASSERTION(aResult, "Bad pointer");
+  *aResult = DataToString("%llu", mData);
+  return NS_OK;
+}
+
+/***************************************************************************/
+
+NS_IMPL_ISUPPORTS(nsSupportsPRTime, nsISupportsPRTime,
+                  nsISupportsPrimitive)
+
+nsSupportsPRTime::nsSupportsPRTime()
+  : mData(0)
+{
+}
+
+NS_IMETHODIMP
+nsSupportsPRTime::GetType(uint16_t* aType)
+{
+  NS_ASSERTION(aType, "Bad pointer");
+  *aType = TYPE_PRTIME;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRTime::GetData(PRTime* aData)
+{
+  NS_ASSERTION(aData, "Bad pointer");
+  *aData = mData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRTime::SetData(PRTime aData)
+{
+  mData = aData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRTime::ToString(char** aResult)
+{
+  NS_ASSERTION(aResult, "Bad pointer");
+  *aResult = DataToString("%" PRIu64, mData);
+  return NS_OK;
+}
+
+/***************************************************************************/
+
+NS_IMPL_ISUPPORTS(nsSupportsChar, nsISupportsChar,
+                  nsISupportsPrimitive)
+
+nsSupportsChar::nsSupportsChar()
+  : mData(0)
+{
+}
+
+NS_IMETHODIMP
+nsSupportsChar::GetType(uint16_t* aType)
+{
+  NS_ASSERTION(aType, "Bad pointer");
+  *aType = TYPE_CHAR;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsChar::GetData(char* aData)
+{
+  NS_ASSERTION(aData, "Bad pointer");
+  *aData = mData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsChar::SetData(char aData)
+{
+  mData = aData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsChar::ToString(char** aResult)
+{
+  NS_ASSERTION(aResult, "Bad pointer");
+  *aResult = static_cast<char*>(moz_xmalloc(2 * sizeof(char)));
+  *aResult[0] = mData;
+  *aResult[1] = '\0';
+
+  return NS_OK;
+}
+
+/***************************************************************************/
+
+NS_IMPL_ISUPPORTS(nsSupportsPRInt16, nsISupportsPRInt16,
+                  nsISupportsPrimitive)
+
+nsSupportsPRInt16::nsSupportsPRInt16()
+  : mData(0)
+{
+}
+
+NS_IMETHODIMP
+nsSupportsPRInt16::GetType(uint16_t* aType)
+{
+  NS_ASSERTION(aType, "Bad pointer");
+  *aType = TYPE_PRINT16;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRInt16::GetData(int16_t* aData)
+{
+  NS_ASSERTION(aData, "Bad pointer");
+  *aData = mData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRInt16::SetData(int16_t aData)
+{
+  mData = aData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRInt16::ToString(char** aResult)
+{
+  NS_ASSERTION(aResult, "Bad pointer");
+  *aResult = DataToString("%d", static_cast<int>(mData));
+  return NS_OK;
+}
+
+/***************************************************************************/
+
+NS_IMPL_ISUPPORTS(nsSupportsPRInt32, nsISupportsPRInt32,
+                  nsISupportsPrimitive)
+
+nsSupportsPRInt32::nsSupportsPRInt32()
+  : mData(0)
+{
+}
+
+NS_IMETHODIMP
+nsSupportsPRInt32::GetType(uint16_t* aType)
+{
+  NS_ASSERTION(aType, "Bad pointer");
+  *aType = TYPE_PRINT32;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRInt32::GetData(int32_t* aData)
+{
+  NS_ASSERTION(aData, "Bad pointer");
+  *aData = mData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRInt32::SetData(int32_t aData)
+{
+  mData = aData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRInt32::ToString(char** aResult)
+{
+  NS_ASSERTION(aResult, "Bad pointer");
+  *aResult = DataToString("%d", mData);
+  return NS_OK;
+}
+
+/***************************************************************************/
+
+NS_IMPL_ISUPPORTS(nsSupportsPRInt64, nsISupportsPRInt64,
+                  nsISupportsPrimitive)
+
+nsSupportsPRInt64::nsSupportsPRInt64()
+  : mData(0)
+{
+}
+
+NS_IMETHODIMP
+nsSupportsPRInt64::GetType(uint16_t* aType)
+{
+  NS_ASSERTION(aType, "Bad pointer");
+  *aType = TYPE_PRINT64;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRInt64::GetData(int64_t* aData)
+{
+  NS_ASSERTION(aData, "Bad pointer");
+  *aData = mData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRInt64::SetData(int64_t aData)
+{
+  mData = aData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsPRInt64::ToString(char** aResult)
+{
+  NS_ASSERTION(aResult, "Bad pointer");
+  *aResult = DataToString("%" PRId64, mData);
+  return NS_OK;
+}
+
+/***************************************************************************/
+
+NS_IMPL_ISUPPORTS(nsSupportsFloat, nsISupportsFloat,
+                  nsISupportsPrimitive)
+
+nsSupportsFloat::nsSupportsFloat()
+  : mData(float(0.0))
+{
+}
+
+NS_IMETHODIMP
+nsSupportsFloat::GetType(uint16_t* aType)
+{
+  NS_ASSERTION(aType, "Bad pointer");
+  *aType = TYPE_FLOAT;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsFloat::GetData(float* aData)
+{
+  NS_ASSERTION(aData, "Bad pointer");
+  *aData = mData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsFloat::SetData(float aData)
+{
+  mData = aData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsFloat::ToString(char** aResult)
+{
+  NS_ASSERTION(aResult, "Bad pointer");
+  *aResult = DataToString("%f", static_cast<double>(mData));
+  return NS_OK;
+}
+
+/***************************************************************************/
+
+NS_IMPL_ISUPPORTS(nsSupportsDouble, nsISupportsDouble,
+                  nsISupportsPrimitive)
+
+nsSupportsDouble::nsSupportsDouble()
+  : mData(double(0.0))
+{
+}
+
+NS_IMETHODIMP
+nsSupportsDouble::GetType(uint16_t* aType)
+{
+  NS_ASSERTION(aType, "Bad pointer");
+  *aType = TYPE_DOUBLE;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsDouble::GetData(double* aData)
+{
+  NS_ASSERTION(aData, "Bad pointer");
+  *aData = mData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsDouble::SetData(double aData)
+{
+  mData = aData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsDouble::ToString(char** aResult)
+{
+  NS_ASSERTION(aResult, "Bad pointer");
+  *aResult = DataToString("%f", mData);
+  return  NS_OK;
+}
+
+/***************************************************************************/
+
+
+NS_IMPL_ISUPPORTS(nsSupportsVoid, nsISupportsVoid,
+                  nsISupportsPrimitive)
+
+nsSupportsVoid::nsSupportsVoid()
+  : mData(nullptr)
+{
+}
+
+NS_IMETHODIMP
+nsSupportsVoid::GetType(uint16_t* aType)
+{
+  NS_ASSERTION(aType, "Bad pointer");
+  *aType = TYPE_VOID;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsVoid::GetData(void** aData)
+{
+  NS_ASSERTION(aData, "Bad pointer");
+  *aData = mData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsVoid::SetData(void* aData)
+{
+  mData = aData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsVoid::ToString(char** aResult)
+{
+  NS_ASSERTION(aResult, "Bad pointer");
+  static const char str[] = "[raw data]";
+  *aResult = static_cast<char*>(nsMemory::Clone(str, sizeof(str)));
+  return NS_OK;
+}
+
+/***************************************************************************/
+
+
+NS_IMPL_ISUPPORTS(nsSupportsInterfacePointer,
+                  nsISupportsInterfacePointer,
+                  nsISupportsPrimitive)
+
+nsSupportsInterfacePointer::nsSupportsInterfacePointer()
+  : mIID(nullptr)
+{
+}
+
+nsSupportsInterfacePointer::~nsSupportsInterfacePointer()
+{
+  if (mIID) {
+    free(mIID);
+  }
+}
+
+NS_IMETHODIMP
+nsSupportsInterfacePointer::GetType(uint16_t* aType)
+{
+  NS_ASSERTION(aType, "Bad pointer");
+  *aType = TYPE_INTERFACE_POINTER;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsInterfacePointer::GetData(nsISupports** aData)
+{
+  NS_ASSERTION(aData, "Bad pointer");
+  *aData = mData;
+  NS_IF_ADDREF(*aData);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsInterfacePointer::SetData(nsISupports* aData)
+{
+  mData = aData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsInterfacePointer::GetDataIID(nsID** aIID)
+{
+  NS_ASSERTION(aIID, "Bad pointer");
+
+  if (mIID) {
+    *aIID = static_cast<nsID*>(nsMemory::Clone(mIID, sizeof(nsID)));
+  } else {
+    *aIID = nullptr;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsInterfacePointer::SetDataIID(const nsID* aIID)
+{
+  if (mIID) {
+    free(mIID);
+  }
+
+  if (aIID) {
+    mIID = static_cast<nsID*>(nsMemory::Clone(aIID, sizeof(nsID)));
+  } else {
+    mIID = nullptr;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsInterfacePointer::ToString(char** aResult)
+{
+  NS_ASSERTION(aResult, "Bad pointer");
+
+  static const char str[] = "[interface pointer]";
+  // jband sez: think about asking nsIInterfaceInfoManager whether
+  // the interface has a known human-readable name
+  *aResult = static_cast<char*>(nsMemory::Clone(str, sizeof(str)));
+  return  NS_OK;
+}
+
+/***************************************************************************/
+
+NS_IMPL_ISUPPORTS(nsSupportsDependentCString, nsISupportsCString,
+                  nsISupportsPrimitive)
+
+nsSupportsDependentCString::nsSupportsDependentCString(const char* aStr)
+  : mData(aStr)
+{ }
+
+NS_IMETHODIMP
+nsSupportsDependentCString::GetType(uint16_t* aType)
+{
+  if (NS_WARN_IF(!aType)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  *aType = TYPE_CSTRING;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsDependentCString::GetData(nsACString& aData)
+{
+  aData = mData;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsDependentCString::ToString(char** aResult)
+{
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  *aResult = ToNewCString(mData);
+  if (!*aResult) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSupportsDependentCString::SetData(const nsACString& aData)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
diff --git a/xpcom/ds/nsSupportsPrimitives.h b/xpcom/ds/nsSupportsPrimitives.h
new file mode 100644
index 000000000..17ed0f47f
--- /dev/null
+++ b/xpcom/ds/nsSupportsPrimitives.h
@@ -0,0 +1,327 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSupportsPrimitives_h__
+#define nsSupportsPrimitives_h__
+
+#include "mozilla/Attributes.h"
+
+#include "nsISupportsPrimitives.h"
+#include "nsCOMPtr.h"
+#include "nsString.h"
+
+class nsSupportsID final : public nsISupportsID
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSID
+
+  nsSupportsID();
+
+private:
+  ~nsSupportsID() {}
+
+  nsID* mData;
+};
+
+/***************************************************************************/
+
+class nsSupportsCString final : public nsISupportsCString
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSCSTRING
+
+  nsSupportsCString() {}
+
+private:
+  ~nsSupportsCString() {}
+
+  nsCString mData;
+};
+
+/***************************************************************************/
+
+class nsSupportsString final : public nsISupportsString
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSSTRING
+
+  nsSupportsString() {}
+
+private:
+  ~nsSupportsString() {}
+
+  nsString mData;
+};
+
+/***************************************************************************/
+
+class nsSupportsPRBool final : public nsISupportsPRBool
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSPRBOOL
+
+  nsSupportsPRBool();
+
+private:
+  ~nsSupportsPRBool() {}
+
+  bool mData;
+};
+
+/***************************************************************************/
+
+class nsSupportsPRUint8 final : public nsISupportsPRUint8
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSPRUINT8
+
+  nsSupportsPRUint8();
+
+private:
+  ~nsSupportsPRUint8() {}
+
+  uint8_t mData;
+};
+
+/***************************************************************************/
+
+class nsSupportsPRUint16 final : public nsISupportsPRUint16
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSPRUINT16
+
+  nsSupportsPRUint16();
+
+private:
+  ~nsSupportsPRUint16() {}
+
+  uint16_t mData;
+};
+
+/***************************************************************************/
+
+class nsSupportsPRUint32 final : public nsISupportsPRUint32
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSPRUINT32
+
+  nsSupportsPRUint32();
+
+private:
+  ~nsSupportsPRUint32() {}
+
+  uint32_t mData;
+};
+
+/***************************************************************************/
+
+class nsSupportsPRUint64 final : public nsISupportsPRUint64
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSPRUINT64
+
+  nsSupportsPRUint64();
+
+private:
+  ~nsSupportsPRUint64() {}
+
+  uint64_t mData;
+};
+
+/***************************************************************************/
+
+class nsSupportsPRTime final : public nsISupportsPRTime
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSPRTIME
+
+  nsSupportsPRTime();
+
+private:
+  ~nsSupportsPRTime() {}
+
+  PRTime mData;
+};
+
+/***************************************************************************/
+
+class nsSupportsChar final : public nsISupportsChar
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSCHAR
+
+  nsSupportsChar();
+
+private:
+  ~nsSupportsChar() {}
+
+  char mData;
+};
+
+/***************************************************************************/
+
+class nsSupportsPRInt16 final : public nsISupportsPRInt16
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSPRINT16
+
+  nsSupportsPRInt16();
+
+private:
+  ~nsSupportsPRInt16() {}
+
+  int16_t mData;
+};
+
+/***************************************************************************/
+
+class nsSupportsPRInt32 final : public nsISupportsPRInt32
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSPRINT32
+
+  nsSupportsPRInt32();
+
+private:
+  ~nsSupportsPRInt32() {}
+
+  int32_t mData;
+};
+
+/***************************************************************************/
+
+class nsSupportsPRInt64 final : public nsISupportsPRInt64
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSPRINT64
+
+  nsSupportsPRInt64();
+
+private:
+  ~nsSupportsPRInt64() {}
+
+  int64_t mData;
+};
+
+/***************************************************************************/
+
+class nsSupportsFloat final : public nsISupportsFloat
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSFLOAT
+
+  nsSupportsFloat();
+
+private:
+  ~nsSupportsFloat() {}
+
+  float mData;
+};
+
+/***************************************************************************/
+
+class nsSupportsDouble final : public nsISupportsDouble
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSDOUBLE
+
+  nsSupportsDouble();
+
+private:
+  ~nsSupportsDouble() {}
+
+  double mData;
+};
+
+/***************************************************************************/
+
+class nsSupportsVoid final : public nsISupportsVoid
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSVOID
+
+  nsSupportsVoid();
+
+private:
+  ~nsSupportsVoid() {}
+
+  void* mData;
+};
+
+/***************************************************************************/
+
+class nsSupportsInterfacePointer final : public nsISupportsInterfacePointer
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSINTERFACEPOINTER
+
+  nsSupportsInterfacePointer();
+
+private:
+  ~nsSupportsInterfacePointer();
+
+  nsCOMPtr<nsISupports> mData;
+  nsID* mIID;
+};
+
+/***************************************************************************/
+
+/**
+ * Wraps a static const char* buffer for use with nsISupportsCString
+ *
+ * Only use this class with static buffers, or arena-allocated buffers of
+ * permanent lifetime!
+ */
+class nsSupportsDependentCString final : public nsISupportsCString
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSCSTRING
+
+  explicit nsSupportsDependentCString(const char* aStr);
+
+private:
+  ~nsSupportsDependentCString() {}
+
+  nsDependentCString mData;
+};
+
+#endif /* nsSupportsPrimitives_h__ */
diff --git a/xpcom/ds/nsVariant.cpp b/xpcom/ds/nsVariant.cpp
new file mode 100644
index 000000000..edb020139
--- /dev/null
+++ b/xpcom/ds/nsVariant.cpp
@@ -0,0 +1,2220 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsVariant.h"
+#include "prprf.h"
+#include "prdtoa.h"
+#include <math.h>
+#include "nsCycleCollectionParticipant.h"
+#include "xpt_struct.h"
+#include "nsReadableUtils.h"
+#include "nsMemory.h"
+#include "nsString.h"
+#include "nsCRTGlue.h"
+
+/***************************************************************************/
+// Helpers for static convert functions...
+
+static nsresult
+String2Double(const char* aString, double* aResult)
+{
+  char* next;
+  double value = PR_strtod(aString, &next);
+  if (next == aString) {
+    return NS_ERROR_CANNOT_CONVERT_DATA;
+  }
+  *aResult = value;
+  return NS_OK;
+}
+
+static nsresult
+AString2Double(const nsAString& aString, double* aResult)
+{
+  char* pChars = ToNewCString(aString);
+  if (!pChars) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  nsresult rv = String2Double(pChars, aResult);
+  free(pChars);
+  return rv;
+}
+
+static nsresult
+AUTF8String2Double(const nsAUTF8String& aString, double* aResult)
+{
+  return String2Double(PromiseFlatUTF8String(aString).get(), aResult);
+}
+
+static nsresult
+ACString2Double(const nsACString& aString, double* aResult)
+{
+  return String2Double(PromiseFlatCString(aString).get(), aResult);
+}
+
+// Fills aOutData with double, uint32_t, or int32_t.
+// Returns NS_OK, an error code, or a non-NS_OK success code
+nsresult
+nsDiscriminatedUnion::ToManageableNumber(nsDiscriminatedUnion* aOutData) const
+{
+  nsresult rv;
+
+  switch (mType) {
+    // This group results in a int32_t...
+
+#define CASE__NUMBER_INT32(type_, member_)                                    \
+    case nsIDataType::type_ :                                                 \
+        aOutData->u.mInt32Value = u.member_ ;                                 \
+        aOutData->mType = nsIDataType::VTYPE_INT32;                           \
+        return NS_OK;
+
+    CASE__NUMBER_INT32(VTYPE_INT8,   mInt8Value)
+    CASE__NUMBER_INT32(VTYPE_INT16,  mInt16Value)
+    CASE__NUMBER_INT32(VTYPE_INT32,  mInt32Value)
+    CASE__NUMBER_INT32(VTYPE_UINT8,  mUint8Value)
+    CASE__NUMBER_INT32(VTYPE_UINT16, mUint16Value)
+    CASE__NUMBER_INT32(VTYPE_BOOL,   mBoolValue)
+    CASE__NUMBER_INT32(VTYPE_CHAR,   mCharValue)
+    CASE__NUMBER_INT32(VTYPE_WCHAR,  mWCharValue)
+
+#undef CASE__NUMBER_INT32
+
+    // This group results in a uint32_t...
+
+    case nsIDataType::VTYPE_UINT32:
+      aOutData->u.mInt32Value = u.mUint32Value;
+      aOutData->mType = nsIDataType::VTYPE_INT32;
+      return NS_OK;
+
+    // This group results in a double...
+
+    case nsIDataType::VTYPE_INT64:
+    case nsIDataType::VTYPE_UINT64:
+      // XXX Need boundary checking here.
+      // We may need to return NS_SUCCESS_LOSS_OF_INSIGNIFICANT_DATA
+      aOutData->u.mDoubleValue = double(u.mInt64Value);
+      aOutData->mType = nsIDataType::VTYPE_DOUBLE;
+      return NS_OK;
+    case nsIDataType::VTYPE_FLOAT:
+      aOutData->u.mDoubleValue = u.mFloatValue;
+      aOutData->mType = nsIDataType::VTYPE_DOUBLE;
+      return NS_OK;
+    case nsIDataType::VTYPE_DOUBLE:
+      aOutData->u.mDoubleValue = u.mDoubleValue;
+      aOutData->mType = nsIDataType::VTYPE_DOUBLE;
+      return NS_OK;
+    case nsIDataType::VTYPE_CHAR_STR:
+    case nsIDataType::VTYPE_STRING_SIZE_IS:
+      rv = String2Double(u.str.mStringValue, &aOutData->u.mDoubleValue);
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+      aOutData->mType = nsIDataType::VTYPE_DOUBLE;
+      return NS_OK;
+    case nsIDataType::VTYPE_DOMSTRING:
+    case nsIDataType::VTYPE_ASTRING:
+      rv = AString2Double(*u.mAStringValue, &aOutData->u.mDoubleValue);
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+      aOutData->mType = nsIDataType::VTYPE_DOUBLE;
+      return NS_OK;
+    case nsIDataType::VTYPE_UTF8STRING:
+      rv = AUTF8String2Double(*u.mUTF8StringValue,
+                              &aOutData->u.mDoubleValue);
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+      aOutData->mType = nsIDataType::VTYPE_DOUBLE;
+      return NS_OK;
+    case nsIDataType::VTYPE_CSTRING:
+      rv = ACString2Double(*u.mCStringValue,
+                           &aOutData->u.mDoubleValue);
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+      aOutData->mType = nsIDataType::VTYPE_DOUBLE;
+      return NS_OK;
+    case nsIDataType::VTYPE_WCHAR_STR:
+    case nsIDataType::VTYPE_WSTRING_SIZE_IS:
+      rv = AString2Double(nsDependentString(u.wstr.mWStringValue),
+                          &aOutData->u.mDoubleValue);
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+      aOutData->mType = nsIDataType::VTYPE_DOUBLE;
+      return NS_OK;
+
+    // This group fails...
+
+    case nsIDataType::VTYPE_VOID:
+    case nsIDataType::VTYPE_ID:
+    case nsIDataType::VTYPE_INTERFACE:
+    case nsIDataType::VTYPE_INTERFACE_IS:
+    case nsIDataType::VTYPE_ARRAY:
+    case nsIDataType::VTYPE_EMPTY_ARRAY:
+    case nsIDataType::VTYPE_EMPTY:
+    default:
+      return NS_ERROR_CANNOT_CONVERT_DATA;
+  }
+}
+
+/***************************************************************************/
+// Array helpers...
+
+void
+nsDiscriminatedUnion::FreeArray()
+{
+  NS_ASSERTION(mType == nsIDataType::VTYPE_ARRAY, "bad FreeArray call");
+  NS_ASSERTION(u.array.mArrayValue, "bad array");
+  NS_ASSERTION(u.array.mArrayCount, "bad array count");
+
+#define CASE__FREE_ARRAY_PTR(type_, ctype_)                                   \
+        case nsIDataType::type_ :                                             \
+        {                                                                     \
+            ctype_** p = (ctype_**) u.array.mArrayValue;                      \
+            for (uint32_t i = u.array.mArrayCount; i > 0; p++, i--)           \
+                if (*p)                                                       \
+                    free((char*)*p);                                          \
+            break;                                                            \
+        }
+
+#define CASE__FREE_ARRAY_IFACE(type_, ctype_)                                 \
+        case nsIDataType::type_ :                                             \
+        {                                                                     \
+            ctype_** p = (ctype_**) u.array.mArrayValue;                      \
+            for (uint32_t i = u.array.mArrayCount; i > 0; p++, i--)           \
+                if (*p)                                                       \
+                    (*p)->Release();                                          \
+            break;                                                            \
+        }
+
+  switch (u.array.mArrayType) {
+    case nsIDataType::VTYPE_INT8:
+    case nsIDataType::VTYPE_INT16:
+    case nsIDataType::VTYPE_INT32:
+    case nsIDataType::VTYPE_INT64:
+    case nsIDataType::VTYPE_UINT8:
+    case nsIDataType::VTYPE_UINT16:
+    case nsIDataType::VTYPE_UINT32:
+    case nsIDataType::VTYPE_UINT64:
+    case nsIDataType::VTYPE_FLOAT:
+    case nsIDataType::VTYPE_DOUBLE:
+    case nsIDataType::VTYPE_BOOL:
+    case nsIDataType::VTYPE_CHAR:
+    case nsIDataType::VTYPE_WCHAR:
+      break;
+
+    // XXX We ASSUME that "array of nsID" means "array of pointers to nsID".
+    CASE__FREE_ARRAY_PTR(VTYPE_ID, nsID)
+    CASE__FREE_ARRAY_PTR(VTYPE_CHAR_STR, char)
+    CASE__FREE_ARRAY_PTR(VTYPE_WCHAR_STR, char16_t)
+    CASE__FREE_ARRAY_IFACE(VTYPE_INTERFACE, nsISupports)
+    CASE__FREE_ARRAY_IFACE(VTYPE_INTERFACE_IS, nsISupports)
+
+    // The rest are illegal.
+    case nsIDataType::VTYPE_VOID:
+    case nsIDataType::VTYPE_ASTRING:
+    case nsIDataType::VTYPE_DOMSTRING:
+    case nsIDataType::VTYPE_UTF8STRING:
+    case nsIDataType::VTYPE_CSTRING:
+    case nsIDataType::VTYPE_WSTRING_SIZE_IS:
+    case nsIDataType::VTYPE_STRING_SIZE_IS:
+    case nsIDataType::VTYPE_ARRAY:
+    case nsIDataType::VTYPE_EMPTY_ARRAY:
+    case nsIDataType::VTYPE_EMPTY:
+    default:
+      NS_ERROR("bad type in array!");
+      break;
+  }
+
+  // Free the array memory.
+  free((char*)u.array.mArrayValue);
+
+#undef CASE__FREE_ARRAY_PTR
+#undef CASE__FREE_ARRAY_IFACE
+}
+
+static nsresult
+CloneArray(uint16_t aInType, const nsIID* aInIID,
+           uint32_t aInCount, void* aInValue,
+           uint16_t* aOutType, nsIID* aOutIID,
+           uint32_t* aOutCount, void** aOutValue)
+{
+  NS_ASSERTION(aInCount, "bad param");
+  NS_ASSERTION(aInValue, "bad param");
+  NS_ASSERTION(aOutType, "bad param");
+  NS_ASSERTION(aOutCount, "bad param");
+  NS_ASSERTION(aOutValue, "bad param");
+
+  uint32_t allocatedValueCount = 0;
+  nsresult rv = NS_OK;
+  uint32_t i;
+
+  // First we figure out the size of the elements for the new u.array.
+
+  size_t elementSize;
+  size_t allocSize;
+
+  switch (aInType) {
+    case nsIDataType::VTYPE_INT8:
+      elementSize = sizeof(int8_t);
+      break;
+    case nsIDataType::VTYPE_INT16:
+      elementSize = sizeof(int16_t);
+      break;
+    case nsIDataType::VTYPE_INT32:
+      elementSize = sizeof(int32_t);
+      break;
+    case nsIDataType::VTYPE_INT64:
+      elementSize = sizeof(int64_t);
+      break;
+    case nsIDataType::VTYPE_UINT8:
+      elementSize = sizeof(uint8_t);
+      break;
+    case nsIDataType::VTYPE_UINT16:
+      elementSize = sizeof(uint16_t);
+      break;
+    case nsIDataType::VTYPE_UINT32:
+      elementSize = sizeof(uint32_t);
+      break;
+    case nsIDataType::VTYPE_UINT64:
+      elementSize = sizeof(uint64_t);
+      break;
+    case nsIDataType::VTYPE_FLOAT:
+      elementSize = sizeof(float);
+      break;
+    case nsIDataType::VTYPE_DOUBLE:
+      elementSize = sizeof(double);
+      break;
+    case nsIDataType::VTYPE_BOOL:
+      elementSize = sizeof(bool);
+      break;
+    case nsIDataType::VTYPE_CHAR:
+      elementSize = sizeof(char);
+      break;
+    case nsIDataType::VTYPE_WCHAR:
+      elementSize = sizeof(char16_t);
+      break;
+
+    // XXX We ASSUME that "array of nsID" means "array of pointers to nsID".
+    case nsIDataType::VTYPE_ID:
+    case nsIDataType::VTYPE_CHAR_STR:
+    case nsIDataType::VTYPE_WCHAR_STR:
+    case nsIDataType::VTYPE_INTERFACE:
+    case nsIDataType::VTYPE_INTERFACE_IS:
+      elementSize = sizeof(void*);
+      break;
+
+    // The rest are illegal.
+    case nsIDataType::VTYPE_ASTRING:
+    case nsIDataType::VTYPE_DOMSTRING:
+    case nsIDataType::VTYPE_UTF8STRING:
+    case nsIDataType::VTYPE_CSTRING:
+    case nsIDataType::VTYPE_STRING_SIZE_IS:
+    case nsIDataType::VTYPE_WSTRING_SIZE_IS:
+    case nsIDataType::VTYPE_VOID:
+    case nsIDataType::VTYPE_ARRAY:
+    case nsIDataType::VTYPE_EMPTY_ARRAY:
+    case nsIDataType::VTYPE_EMPTY:
+    default:
+      NS_ERROR("bad type in array!");
+      return NS_ERROR_CANNOT_CONVERT_DATA;
+  }
+
+
+  // Alloc the u.array.
+
+  allocSize = aInCount * elementSize;
+  *aOutValue = moz_xmalloc(allocSize);
+  if (!*aOutValue) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  // Clone the elements.
+
+  switch (aInType) {
+    case nsIDataType::VTYPE_INT8:
+    case nsIDataType::VTYPE_INT16:
+    case nsIDataType::VTYPE_INT32:
+    case nsIDataType::VTYPE_INT64:
+    case nsIDataType::VTYPE_UINT8:
+    case nsIDataType::VTYPE_UINT16:
+    case nsIDataType::VTYPE_UINT32:
+    case nsIDataType::VTYPE_UINT64:
+    case nsIDataType::VTYPE_FLOAT:
+    case nsIDataType::VTYPE_DOUBLE:
+    case nsIDataType::VTYPE_BOOL:
+    case nsIDataType::VTYPE_CHAR:
+    case nsIDataType::VTYPE_WCHAR:
+      memcpy(*aOutValue, aInValue, allocSize);
+      break;
+
+    case nsIDataType::VTYPE_INTERFACE_IS:
+      if (aOutIID) {
+        *aOutIID = *aInIID;
+      }
+      MOZ_FALLTHROUGH;
+
+    case nsIDataType::VTYPE_INTERFACE: {
+      memcpy(*aOutValue, aInValue, allocSize);
+
+      nsISupports** p = (nsISupports**)*aOutValue;
+      for (i = aInCount; i > 0; ++p, --i)
+        if (*p) {
+          (*p)->AddRef();
+        }
+      break;
+    }
+
+    // XXX We ASSUME that "array of nsID" means "array of pointers to nsID".
+    case nsIDataType::VTYPE_ID: {
+      nsID** inp  = (nsID**)aInValue;
+      nsID** outp = (nsID**)*aOutValue;
+      for (i = aInCount; i > 0; --i) {
+        nsID* idp = *(inp++);
+        if (idp) {
+          if (!(*(outp++) = (nsID*)nsMemory::Clone((char*)idp, sizeof(nsID)))) {
+            goto bad;
+          }
+        } else {
+          *(outp++) = nullptr;
+        }
+        allocatedValueCount++;
+      }
+      break;
+    }
+
+    case nsIDataType::VTYPE_CHAR_STR: {
+      char** inp  = (char**)aInValue;
+      char** outp = (char**)*aOutValue;
+      for (i = aInCount; i > 0; i--) {
+        char* str = *(inp++);
+        if (str) {
+          if (!(*(outp++) = (char*)nsMemory::Clone(
+                              str, (strlen(str) + 1) * sizeof(char)))) {
+            goto bad;
+          }
+        } else {
+          *(outp++) = nullptr;
+        }
+        allocatedValueCount++;
+      }
+      break;
+    }
+
+    case nsIDataType::VTYPE_WCHAR_STR: {
+      char16_t** inp  = (char16_t**)aInValue;
+      char16_t** outp = (char16_t**)*aOutValue;
+      for (i = aInCount; i > 0; i--) {
+        char16_t* str = *(inp++);
+        if (str) {
+          if (!(*(outp++) = (char16_t*)nsMemory::Clone(
+                              str, (NS_strlen(str) + 1) * sizeof(char16_t)))) {
+            goto bad;
+          }
+        } else {
+          *(outp++) = nullptr;
+        }
+        allocatedValueCount++;
+      }
+      break;
+    }
+
+    // The rest are illegal.
+    case nsIDataType::VTYPE_VOID:
+    case nsIDataType::VTYPE_ARRAY:
+    case nsIDataType::VTYPE_EMPTY_ARRAY:
+    case nsIDataType::VTYPE_EMPTY:
+    case nsIDataType::VTYPE_ASTRING:
+    case nsIDataType::VTYPE_DOMSTRING:
+    case nsIDataType::VTYPE_UTF8STRING:
+    case nsIDataType::VTYPE_CSTRING:
+    case nsIDataType::VTYPE_STRING_SIZE_IS:
+    case nsIDataType::VTYPE_WSTRING_SIZE_IS:
+    default:
+      NS_ERROR("bad type in array!");
+      return NS_ERROR_CANNOT_CONVERT_DATA;
+  }
+
+  *aOutType = aInType;
+  *aOutCount = aInCount;
+  return NS_OK;
+
+bad:
+  if (*aOutValue) {
+    char** p = (char**)*aOutValue;
+    for (i = allocatedValueCount; i > 0; ++p, --i)
+      if (*p) {
+        free(*p);
+      }
+    free((char*)*aOutValue);
+    *aOutValue = nullptr;
+  }
+  return rv;
+}
+
+/***************************************************************************/
+
+#define TRIVIAL_DATA_CONVERTER(type_, member_, retval_)                       \
+    if (mType == nsIDataType::type_) {                                        \
+        *retval_ = u.member_;                                                 \
+        return NS_OK;                                                         \
+    }
+
+#define NUMERIC_CONVERSION_METHOD_BEGIN(type_, Ctype_, name_)                 \
+nsresult                                                                      \
+nsDiscriminatedUnion::ConvertTo##name_ (Ctype_* aResult) const                \
+{                                                                             \
+    TRIVIAL_DATA_CONVERTER(type_, m##name_##Value, aResult)                   \
+    nsDiscriminatedUnion tempData;                                            \
+    nsresult rv = ToManageableNumber(&tempData);                              \
+    /*                                                                     */ \
+    /* NOTE: rv may indicate a success code that we want to preserve       */ \
+    /* For the final return. So all the return cases below should return   */ \
+    /* this rv when indicating success.                                    */ \
+    /*                                                                     */ \
+    if (NS_FAILED(rv))                                                        \
+        return rv;                                                            \
+    switch(tempData.mType)                                                    \
+    {
+
+#define CASE__NUMERIC_CONVERSION_INT32_JUST_CAST(Ctype_)                      \
+    case nsIDataType::VTYPE_INT32:                                            \
+        *aResult = ( Ctype_ ) tempData.u.mInt32Value;                         \
+        return rv;
+
+#define CASE__NUMERIC_CONVERSION_INT32_MIN_MAX(Ctype_, min_, max_)            \
+    case nsIDataType::VTYPE_INT32:                                            \
+    {                                                                         \
+        int32_t value = tempData.u.mInt32Value;                               \
+        if (value < min_ || value > max_)                                     \
+            return NS_ERROR_LOSS_OF_SIGNIFICANT_DATA;                         \
+        *aResult = ( Ctype_ ) value;                                          \
+        return rv;                                                            \
+    }
+
+#define CASE__NUMERIC_CONVERSION_UINT32_JUST_CAST(Ctype_)                     \
+    case nsIDataType::VTYPE_UINT32:                                           \
+        *aResult = ( Ctype_ ) tempData.u.mUint32Value;                        \
+        return rv;
+
+#define CASE__NUMERIC_CONVERSION_UINT32_MAX(Ctype_, max_)                     \
+    case nsIDataType::VTYPE_UINT32:                                           \
+    {                                                                         \
+        uint32_t value = tempData.u.mUint32Value;                             \
+        if (value > max_)                                                     \
+            return NS_ERROR_LOSS_OF_SIGNIFICANT_DATA;                         \
+        *aResult = ( Ctype_ ) value;                                          \
+        return rv;                                                            \
+    }
+
+#define CASE__NUMERIC_CONVERSION_DOUBLE_JUST_CAST(Ctype_)                     \
+    case nsIDataType::VTYPE_DOUBLE:                                           \
+        *aResult = ( Ctype_ ) tempData.u.mDoubleValue;                        \
+        return rv;
+
+#define CASE__NUMERIC_CONVERSION_DOUBLE_MIN_MAX(Ctype_, min_, max_)           \
+    case nsIDataType::VTYPE_DOUBLE:                                           \
+    {                                                                         \
+        double value = tempData.u.mDoubleValue;                               \
+        if (value < min_ || value > max_)                                     \
+            return NS_ERROR_LOSS_OF_SIGNIFICANT_DATA;                         \
+        *aResult = ( Ctype_ ) value;                                          \
+        return rv;                                                            \
+    }
+
+#define CASE__NUMERIC_CONVERSION_DOUBLE_MIN_MAX_INT(Ctype_, min_, max_)       \
+    case nsIDataType::VTYPE_DOUBLE:                                           \
+    {                                                                         \
+        double value = tempData.u.mDoubleValue;                               \
+        if (value < min_ || value > max_)                                     \
+            return NS_ERROR_LOSS_OF_SIGNIFICANT_DATA;                         \
+        *aResult = ( Ctype_ ) value;                                          \
+        return (0.0 == fmod(value,1.0)) ?                                     \
+            rv : NS_SUCCESS_LOSS_OF_INSIGNIFICANT_DATA;                       \
+    }
+
+#define CASES__NUMERIC_CONVERSION_NORMAL(Ctype_, min_, max_)                  \
+    CASE__NUMERIC_CONVERSION_INT32_MIN_MAX(Ctype_, min_, max_)                \
+    CASE__NUMERIC_CONVERSION_UINT32_MAX(Ctype_, max_)                         \
+    CASE__NUMERIC_CONVERSION_DOUBLE_MIN_MAX_INT(Ctype_, min_, max_)
+
+#define NUMERIC_CONVERSION_METHOD_END                                         \
+    default:                                                                  \
+        NS_ERROR("bad type returned from ToManageableNumber");                \
+        return NS_ERROR_CANNOT_CONVERT_DATA;                                  \
+    }                                                                         \
+}
+
+#define NUMERIC_CONVERSION_METHOD_NORMAL(type_, Ctype_, name_, min_, max_)    \
+    NUMERIC_CONVERSION_METHOD_BEGIN(type_, Ctype_, name_)                     \
+        CASES__NUMERIC_CONVERSION_NORMAL(Ctype_, min_, max_)                  \
+    NUMERIC_CONVERSION_METHOD_END
+
+/***************************************************************************/
+// These expand into full public methods...
+
+NUMERIC_CONVERSION_METHOD_NORMAL(VTYPE_INT8, uint8_t, Int8, (-127 - 1), 127)
+NUMERIC_CONVERSION_METHOD_NORMAL(VTYPE_INT16, int16_t, Int16, (-32767 - 1), 32767)
+
+NUMERIC_CONVERSION_METHOD_BEGIN(VTYPE_INT32, int32_t, Int32)
+  CASE__NUMERIC_CONVERSION_INT32_JUST_CAST(int32_t)
+  CASE__NUMERIC_CONVERSION_UINT32_MAX(int32_t, 2147483647)
+  CASE__NUMERIC_CONVERSION_DOUBLE_MIN_MAX_INT(int32_t, (-2147483647 - 1), 2147483647)
+NUMERIC_CONVERSION_METHOD_END
+
+NUMERIC_CONVERSION_METHOD_NORMAL(VTYPE_UINT8, uint8_t, Uint8, 0, 255)
+NUMERIC_CONVERSION_METHOD_NORMAL(VTYPE_UINT16, uint16_t, Uint16, 0, 65535)
+
+NUMERIC_CONVERSION_METHOD_BEGIN(VTYPE_UINT32, uint32_t, Uint32)
+  CASE__NUMERIC_CONVERSION_INT32_MIN_MAX(uint32_t, 0, 2147483647)
+  CASE__NUMERIC_CONVERSION_UINT32_JUST_CAST(uint32_t)
+  CASE__NUMERIC_CONVERSION_DOUBLE_MIN_MAX_INT(uint32_t, 0, 4294967295U)
+NUMERIC_CONVERSION_METHOD_END
+
+// XXX toFloat convertions need to be fixed!
+NUMERIC_CONVERSION_METHOD_BEGIN(VTYPE_FLOAT, float, Float)
+  CASE__NUMERIC_CONVERSION_INT32_JUST_CAST(float)
+  CASE__NUMERIC_CONVERSION_UINT32_JUST_CAST(float)
+  CASE__NUMERIC_CONVERSION_DOUBLE_JUST_CAST(float)
+NUMERIC_CONVERSION_METHOD_END
+
+NUMERIC_CONVERSION_METHOD_BEGIN(VTYPE_DOUBLE, double, Double)
+  CASE__NUMERIC_CONVERSION_INT32_JUST_CAST(double)
+  CASE__NUMERIC_CONVERSION_UINT32_JUST_CAST(double)
+  CASE__NUMERIC_CONVERSION_DOUBLE_JUST_CAST(double)
+NUMERIC_CONVERSION_METHOD_END
+
+// XXX toChar convertions need to be fixed!
+NUMERIC_CONVERSION_METHOD_BEGIN(VTYPE_CHAR, char, Char)
+  CASE__NUMERIC_CONVERSION_INT32_JUST_CAST(char)
+  CASE__NUMERIC_CONVERSION_UINT32_JUST_CAST(char)
+  CASE__NUMERIC_CONVERSION_DOUBLE_JUST_CAST(char)
+NUMERIC_CONVERSION_METHOD_END
+
+// XXX toWChar convertions need to be fixed!
+NUMERIC_CONVERSION_METHOD_BEGIN(VTYPE_WCHAR, char16_t, WChar)
+  CASE__NUMERIC_CONVERSION_INT32_JUST_CAST(char16_t)
+  CASE__NUMERIC_CONVERSION_UINT32_JUST_CAST(char16_t)
+  CASE__NUMERIC_CONVERSION_DOUBLE_JUST_CAST(char16_t)
+NUMERIC_CONVERSION_METHOD_END
+
+#undef NUMERIC_CONVERSION_METHOD_BEGIN
+#undef CASE__NUMERIC_CONVERSION_INT32_JUST_CAST
+#undef CASE__NUMERIC_CONVERSION_INT32_MIN_MAX
+#undef CASE__NUMERIC_CONVERSION_UINT32_JUST_CAST
+#undef CASE__NUMERIC_CONVERSION_UINT32_MIN_MAX
+#undef CASE__NUMERIC_CONVERSION_DOUBLE_JUST_CAST
+#undef CASE__NUMERIC_CONVERSION_DOUBLE_MIN_MAX
+#undef CASE__NUMERIC_CONVERSION_DOUBLE_MIN_MAX_INT
+#undef CASES__NUMERIC_CONVERSION_NORMAL
+#undef NUMERIC_CONVERSION_METHOD_END
+#undef NUMERIC_CONVERSION_METHOD_NORMAL
+
+/***************************************************************************/
+
+// Just leverage a numeric converter for bool (but restrict the values).
+// XXX Is this really what we want to do?
+
+nsresult
+nsDiscriminatedUnion::ConvertToBool(bool* aResult) const
+{
+  TRIVIAL_DATA_CONVERTER(VTYPE_BOOL, mBoolValue, aResult)
+
+  double val;
+  nsresult rv = ConvertToDouble(&val);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  *aResult = 0.0 != val;
+  return rv;
+}
+
+/***************************************************************************/
+
+nsresult
+nsDiscriminatedUnion::ConvertToInt64(int64_t* aResult) const
+{
+  TRIVIAL_DATA_CONVERTER(VTYPE_INT64, mInt64Value, aResult)
+  TRIVIAL_DATA_CONVERTER(VTYPE_UINT64, mUint64Value, aResult)
+
+  nsDiscriminatedUnion tempData;
+  nsresult rv = ToManageableNumber(&tempData);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  switch (tempData.mType) {
+    case nsIDataType::VTYPE_INT32:
+      *aResult = tempData.u.mInt32Value;
+      return rv;
+    case nsIDataType::VTYPE_UINT32:
+      *aResult = tempData.u.mUint32Value;
+      return rv;
+    case nsIDataType::VTYPE_DOUBLE:
+      // XXX should check for data loss here!
+      *aResult = tempData.u.mDoubleValue;
+      return rv;
+    default:
+      NS_ERROR("bad type returned from ToManageableNumber");
+      return NS_ERROR_CANNOT_CONVERT_DATA;
+  }
+}
+
+nsresult
+nsDiscriminatedUnion::ConvertToUint64(uint64_t* aResult) const
+{
+  return ConvertToInt64((int64_t*)aResult);
+}
+
+/***************************************************************************/
+
+bool
+nsDiscriminatedUnion::String2ID(nsID* aPid) const
+{
+  nsAutoString tempString;
+  nsAString* pString;
+
+  switch (mType) {
+    case nsIDataType::VTYPE_CHAR_STR:
+    case nsIDataType::VTYPE_STRING_SIZE_IS:
+      return aPid->Parse(u.str.mStringValue);
+    case nsIDataType::VTYPE_CSTRING:
+      return aPid->Parse(PromiseFlatCString(*u.mCStringValue).get());
+    case nsIDataType::VTYPE_UTF8STRING:
+      return aPid->Parse(PromiseFlatUTF8String(*u.mUTF8StringValue).get());
+    case nsIDataType::VTYPE_ASTRING:
+    case nsIDataType::VTYPE_DOMSTRING:
+      pString = u.mAStringValue;
+      break;
+    case nsIDataType::VTYPE_WCHAR_STR:
+    case nsIDataType::VTYPE_WSTRING_SIZE_IS:
+      tempString.Assign(u.wstr.mWStringValue);
+      pString = &tempString;
+      break;
+    default:
+      NS_ERROR("bad type in call to String2ID");
+      return false;
+  }
+
+  char* pChars = ToNewCString(*pString);
+  if (!pChars) {
+    return false;
+  }
+  bool result = aPid->Parse(pChars);
+  free(pChars);
+  return result;
+}
+
+nsresult
+nsDiscriminatedUnion::ConvertToID(nsID* aResult) const
+{
+  nsID id;
+
+  switch (mType) {
+    case nsIDataType::VTYPE_ID:
+      *aResult = u.mIDValue;
+      return NS_OK;
+    case nsIDataType::VTYPE_INTERFACE:
+      *aResult = NS_GET_IID(nsISupports);
+      return NS_OK;
+    case nsIDataType::VTYPE_INTERFACE_IS:
+      *aResult = u.iface.mInterfaceID;
+      return NS_OK;
+    case nsIDataType::VTYPE_ASTRING:
+    case nsIDataType::VTYPE_DOMSTRING:
+    case nsIDataType::VTYPE_UTF8STRING:
+    case nsIDataType::VTYPE_CSTRING:
+    case nsIDataType::VTYPE_CHAR_STR:
+    case nsIDataType::VTYPE_WCHAR_STR:
+    case nsIDataType::VTYPE_STRING_SIZE_IS:
+    case nsIDataType::VTYPE_WSTRING_SIZE_IS:
+      if (!String2ID(&id)) {
+        return NS_ERROR_CANNOT_CONVERT_DATA;
+      }
+      *aResult = id;
+      return NS_OK;
+    default:
+      return NS_ERROR_CANNOT_CONVERT_DATA;
+  }
+}
+
+/***************************************************************************/
+
+nsresult
+nsDiscriminatedUnion::ToString(nsACString& aOutString) const
+{
+  char* ptr;
+
+  switch (mType) {
+    // all the stuff we don't handle...
+    case nsIDataType::VTYPE_ASTRING:
+    case nsIDataType::VTYPE_DOMSTRING:
+    case nsIDataType::VTYPE_UTF8STRING:
+    case nsIDataType::VTYPE_CSTRING:
+    case nsIDataType::VTYPE_CHAR_STR:
+    case nsIDataType::VTYPE_WCHAR_STR:
+    case nsIDataType::VTYPE_STRING_SIZE_IS:
+    case nsIDataType::VTYPE_WSTRING_SIZE_IS:
+    case nsIDataType::VTYPE_WCHAR:
+      NS_ERROR("ToString being called for a string type - screwy logic!");
+      MOZ_FALLTHROUGH;
+
+    // XXX We might want stringified versions of these... ???
+
+    case nsIDataType::VTYPE_VOID:
+    case nsIDataType::VTYPE_EMPTY:
+      aOutString.SetIsVoid(true);
+      return NS_OK;
+
+    case nsIDataType::VTYPE_EMPTY_ARRAY:
+    case nsIDataType::VTYPE_ARRAY:
+    case nsIDataType::VTYPE_INTERFACE:
+    case nsIDataType::VTYPE_INTERFACE_IS:
+    default:
+      return NS_ERROR_CANNOT_CONVERT_DATA;
+
+    // nsID has its own text formatter.
+
+    case nsIDataType::VTYPE_ID:
+      ptr = u.mIDValue.ToString();
+      if (!ptr) {
+        return NS_ERROR_OUT_OF_MEMORY;
+      }
+      aOutString.Assign(ptr);
+      free(ptr);
+      return NS_OK;
+
+    // Can't use PR_smprintf for floats, since it's locale-dependent
+#define CASE__APPENDFLOAT_NUMBER(type_, member_)                        \
+    case nsIDataType::type_ :                                           \
+    {                                                                   \
+        nsAutoCString str;                                              \
+        str.AppendFloat(u.member_);                                     \
+        aOutString.Assign(str);                                         \
+        return NS_OK;                                                   \
+    }
+
+    CASE__APPENDFLOAT_NUMBER(VTYPE_FLOAT,  mFloatValue)
+    CASE__APPENDFLOAT_NUMBER(VTYPE_DOUBLE, mDoubleValue)
+
+#undef CASE__APPENDFLOAT_NUMBER
+
+    // the rest can be PR_smprintf'd and use common code.
+
+#define CASE__SMPRINTF_NUMBER(type_, format_, cast_, member_)          \
+    case nsIDataType::type_:                                           \
+        ptr = PR_smprintf( format_ , (cast_) u.member_);               \
+        break;
+
+    CASE__SMPRINTF_NUMBER(VTYPE_INT8,   "%d",   int,      mInt8Value)
+    CASE__SMPRINTF_NUMBER(VTYPE_INT16,  "%d",   int,      mInt16Value)
+    CASE__SMPRINTF_NUMBER(VTYPE_INT32,  "%d",   int,      mInt32Value)
+    CASE__SMPRINTF_NUMBER(VTYPE_INT64,  "%lld", int64_t,  mInt64Value)
+
+    CASE__SMPRINTF_NUMBER(VTYPE_UINT8,  "%u",   unsigned, mUint8Value)
+    CASE__SMPRINTF_NUMBER(VTYPE_UINT16, "%u",   unsigned, mUint16Value)
+    CASE__SMPRINTF_NUMBER(VTYPE_UINT32, "%u",   unsigned, mUint32Value)
+    CASE__SMPRINTF_NUMBER(VTYPE_UINT64, "%llu", int64_t,  mUint64Value)
+
+    // XXX Would we rather print "true" / "false" ?
+    CASE__SMPRINTF_NUMBER(VTYPE_BOOL,   "%d",   int,      mBoolValue)
+
+    CASE__SMPRINTF_NUMBER(VTYPE_CHAR,   "%c",   char,     mCharValue)
+
+#undef CASE__SMPRINTF_NUMBER
+  }
+
+  if (!ptr) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  aOutString.Assign(ptr);
+  PR_smprintf_free(ptr);
+  return NS_OK;
+}
+
+nsresult
+nsDiscriminatedUnion::ConvertToAString(nsAString& aResult) const
+{
+  switch (mType) {
+    case nsIDataType::VTYPE_ASTRING:
+    case nsIDataType::VTYPE_DOMSTRING:
+      aResult.Assign(*u.mAStringValue);
+      return NS_OK;
+    case nsIDataType::VTYPE_CSTRING:
+      CopyASCIItoUTF16(*u.mCStringValue, aResult);
+      return NS_OK;
+    case nsIDataType::VTYPE_UTF8STRING:
+      CopyUTF8toUTF16(*u.mUTF8StringValue, aResult);
+      return NS_OK;
+    case nsIDataType::VTYPE_CHAR_STR:
+      CopyASCIItoUTF16(u.str.mStringValue, aResult);
+      return NS_OK;
+    case nsIDataType::VTYPE_WCHAR_STR:
+      aResult.Assign(u.wstr.mWStringValue);
+      return NS_OK;
+    case nsIDataType::VTYPE_STRING_SIZE_IS:
+      CopyASCIItoUTF16(nsDependentCString(u.str.mStringValue,
+                                          u.str.mStringLength),
+                       aResult);
+      return NS_OK;
+    case nsIDataType::VTYPE_WSTRING_SIZE_IS:
+      aResult.Assign(u.wstr.mWStringValue, u.wstr.mWStringLength);
+      return NS_OK;
+    case nsIDataType::VTYPE_WCHAR:
+      aResult.Assign(u.mWCharValue);
+      return NS_OK;
+    default: {
+      nsAutoCString tempCString;
+      nsresult rv = ToString(tempCString);
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+      CopyASCIItoUTF16(tempCString, aResult);
+      return NS_OK;
+    }
+  }
+}
+
+nsresult
+nsDiscriminatedUnion::ConvertToACString(nsACString& aResult) const
+{
+  switch (mType) {
+    case nsIDataType::VTYPE_ASTRING:
+    case nsIDataType::VTYPE_DOMSTRING:
+      LossyCopyUTF16toASCII(*u.mAStringValue, aResult);
+      return NS_OK;
+    case nsIDataType::VTYPE_CSTRING:
+      aResult.Assign(*u.mCStringValue);
+      return NS_OK;
+    case nsIDataType::VTYPE_UTF8STRING:
+      // XXX This is an extra copy that should be avoided
+      // once Jag lands support for UTF8String and associated
+      // conversion methods.
+      LossyCopyUTF16toASCII(NS_ConvertUTF8toUTF16(*u.mUTF8StringValue),
+                            aResult);
+      return NS_OK;
+    case nsIDataType::VTYPE_CHAR_STR:
+      aResult.Assign(*u.str.mStringValue);
+      return NS_OK;
+    case nsIDataType::VTYPE_WCHAR_STR:
+      LossyCopyUTF16toASCII(nsDependentString(u.wstr.mWStringValue),
+                            aResult);
+      return NS_OK;
+    case nsIDataType::VTYPE_STRING_SIZE_IS:
+      aResult.Assign(u.str.mStringValue, u.str.mStringLength);
+      return NS_OK;
+    case nsIDataType::VTYPE_WSTRING_SIZE_IS:
+      LossyCopyUTF16toASCII(nsDependentString(u.wstr.mWStringValue,
+                                              u.wstr.mWStringLength),
+                            aResult);
+      return NS_OK;
+    case nsIDataType::VTYPE_WCHAR: {
+      const char16_t* str = &u.mWCharValue;
+      LossyCopyUTF16toASCII(Substring(str, 1), aResult);
+      return NS_OK;
+    }
+    default:
+      return ToString(aResult);
+  }
+}
+
+nsresult
+nsDiscriminatedUnion::ConvertToAUTF8String(nsAUTF8String& aResult) const
+{
+  switch (mType) {
+    case nsIDataType::VTYPE_ASTRING:
+    case nsIDataType::VTYPE_DOMSTRING:
+      CopyUTF16toUTF8(*u.mAStringValue, aResult);
+      return NS_OK;
+    case nsIDataType::VTYPE_CSTRING:
+      // XXX Extra copy, can be removed if we're sure CSTRING can
+      //     only contain ASCII.
+      CopyUTF16toUTF8(NS_ConvertASCIItoUTF16(*u.mCStringValue),
+                      aResult);
+      return NS_OK;
+    case nsIDataType::VTYPE_UTF8STRING:
+      aResult.Assign(*u.mUTF8StringValue);
+      return NS_OK;
+    case nsIDataType::VTYPE_CHAR_STR:
+      // XXX Extra copy, can be removed if we're sure CHAR_STR can
+      //     only contain ASCII.
+      CopyUTF16toUTF8(NS_ConvertASCIItoUTF16(u.str.mStringValue),
+                      aResult);
+      return NS_OK;
+    case nsIDataType::VTYPE_WCHAR_STR:
+      CopyUTF16toUTF8(u.wstr.mWStringValue, aResult);
+      return NS_OK;
+    case nsIDataType::VTYPE_STRING_SIZE_IS:
+      // XXX Extra copy, can be removed if we're sure CHAR_STR can
+      //     only contain ASCII.
+      CopyUTF16toUTF8(NS_ConvertASCIItoUTF16(
+        nsDependentCString(u.str.mStringValue,
+                           u.str.mStringLength)), aResult);
+      return NS_OK;
+    case nsIDataType::VTYPE_WSTRING_SIZE_IS:
+      CopyUTF16toUTF8(nsDependentString(u.wstr.mWStringValue,
+                                        u.wstr.mWStringLength),
+                      aResult);
+      return NS_OK;
+    case nsIDataType::VTYPE_WCHAR: {
+      const char16_t* str = &u.mWCharValue;
+      CopyUTF16toUTF8(Substring(str, 1), aResult);
+      return NS_OK;
+    }
+    default: {
+      nsAutoCString tempCString;
+      nsresult rv = ToString(tempCString);
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+      // XXX Extra copy, can be removed if we're sure tempCString can
+      //     only contain ASCII.
+      CopyUTF16toUTF8(NS_ConvertASCIItoUTF16(tempCString), aResult);
+      return NS_OK;
+    }
+  }
+}
+
+nsresult
+nsDiscriminatedUnion::ConvertToString(char** aResult) const
+{
+  uint32_t ignored;
+  return ConvertToStringWithSize(&ignored, aResult);
+}
+
+nsresult
+nsDiscriminatedUnion::ConvertToWString(char16_t** aResult) const
+{
+  uint32_t ignored;
+  return ConvertToWStringWithSize(&ignored, aResult);
+}
+
+nsresult
+nsDiscriminatedUnion::ConvertToStringWithSize(uint32_t* aSize, char** aStr) const
+{
+  nsAutoString  tempString;
+  nsAutoCString tempCString;
+  nsresult rv;
+
+  switch (mType) {
+    case nsIDataType::VTYPE_ASTRING:
+    case nsIDataType::VTYPE_DOMSTRING:
+      *aSize = u.mAStringValue->Length();
+      *aStr = ToNewCString(*u.mAStringValue);
+      break;
+    case nsIDataType::VTYPE_CSTRING:
+      *aSize = u.mCStringValue->Length();
+      *aStr = ToNewCString(*u.mCStringValue);
+      break;
+    case nsIDataType::VTYPE_UTF8STRING: {
+      // XXX This is doing 1 extra copy.  Need to fix this
+      // when Jag lands UTF8String
+      // we want:
+      // *aSize = *mUTF8StringValue->Length();
+      // *aStr = ToNewCString(*mUTF8StringValue);
+      // But this will have to do for now.
+      const NS_ConvertUTF8toUTF16 tempString16(*u.mUTF8StringValue);
+      *aSize = tempString16.Length();
+      *aStr = ToNewCString(tempString16);
+      break;
+    }
+    case nsIDataType::VTYPE_CHAR_STR: {
+      nsDependentCString cString(u.str.mStringValue);
+      *aSize = cString.Length();
+      *aStr = ToNewCString(cString);
+      break;
+    }
+    case nsIDataType::VTYPE_WCHAR_STR: {
+      nsDependentString string(u.wstr.mWStringValue);
+      *aSize = string.Length();
+      *aStr = ToNewCString(string);
+      break;
+    }
+    case nsIDataType::VTYPE_STRING_SIZE_IS: {
+      nsDependentCString cString(u.str.mStringValue,
+                                 u.str.mStringLength);
+      *aSize = cString.Length();
+      *aStr = ToNewCString(cString);
+      break;
+    }
+    case nsIDataType::VTYPE_WSTRING_SIZE_IS: {
+      nsDependentString string(u.wstr.mWStringValue,
+                               u.wstr.mWStringLength);
+      *aSize = string.Length();
+      *aStr = ToNewCString(string);
+      break;
+    }
+    case nsIDataType::VTYPE_WCHAR:
+      tempString.Assign(u.mWCharValue);
+      *aSize = tempString.Length();
+      *aStr = ToNewCString(tempString);
+      break;
+    default:
+      rv = ToString(tempCString);
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+      *aSize = tempCString.Length();
+      *aStr = ToNewCString(tempCString);
+      break;
+  }
+
+  return *aStr ? NS_OK : NS_ERROR_OUT_OF_MEMORY;
+}
+nsresult
+nsDiscriminatedUnion::ConvertToWStringWithSize(uint32_t* aSize, char16_t** aStr) const
+{
+  nsAutoString  tempString;
+  nsAutoCString tempCString;
+  nsresult rv;
+
+  switch (mType) {
+    case nsIDataType::VTYPE_ASTRING:
+    case nsIDataType::VTYPE_DOMSTRING:
+      *aSize = u.mAStringValue->Length();
+      *aStr = ToNewUnicode(*u.mAStringValue);
+      break;
+    case nsIDataType::VTYPE_CSTRING:
+      *aSize = u.mCStringValue->Length();
+      *aStr = ToNewUnicode(*u.mCStringValue);
+      break;
+    case nsIDataType::VTYPE_UTF8STRING: {
+      *aStr = UTF8ToNewUnicode(*u.mUTF8StringValue, aSize);
+      break;
+    }
+    case nsIDataType::VTYPE_CHAR_STR: {
+      nsDependentCString cString(u.str.mStringValue);
+      *aSize = cString.Length();
+      *aStr = ToNewUnicode(cString);
+      break;
+    }
+    case nsIDataType::VTYPE_WCHAR_STR: {
+      nsDependentString string(u.wstr.mWStringValue);
+      *aSize = string.Length();
+      *aStr = ToNewUnicode(string);
+      break;
+    }
+    case nsIDataType::VTYPE_STRING_SIZE_IS: {
+      nsDependentCString cString(u.str.mStringValue,
+                                 u.str.mStringLength);
+      *aSize = cString.Length();
+      *aStr = ToNewUnicode(cString);
+      break;
+    }
+    case nsIDataType::VTYPE_WSTRING_SIZE_IS: {
+      nsDependentString string(u.wstr.mWStringValue,
+                               u.wstr.mWStringLength);
+      *aSize = string.Length();
+      *aStr = ToNewUnicode(string);
+      break;
+    }
+    case nsIDataType::VTYPE_WCHAR:
+      tempString.Assign(u.mWCharValue);
+      *aSize = tempString.Length();
+      *aStr = ToNewUnicode(tempString);
+      break;
+    default:
+      rv = ToString(tempCString);
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+      *aSize = tempCString.Length();
+      *aStr = ToNewUnicode(tempCString);
+      break;
+  }
+
+  return *aStr ? NS_OK : NS_ERROR_OUT_OF_MEMORY;
+}
+
+nsresult
+nsDiscriminatedUnion::ConvertToISupports(nsISupports** aResult) const
+{
+  switch (mType) {
+    case nsIDataType::VTYPE_INTERFACE:
+    case nsIDataType::VTYPE_INTERFACE_IS:
+      if (u.iface.mInterfaceValue) {
+        return u.iface.mInterfaceValue->
+          QueryInterface(NS_GET_IID(nsISupports), (void**)aResult);
+      } else {
+        *aResult = nullptr;
+        return NS_OK;
+      }
+    default:
+      return NS_ERROR_CANNOT_CONVERT_DATA;
+  }
+}
+
+nsresult
+nsDiscriminatedUnion::ConvertToInterface(nsIID** aIID,
+                                         void** aInterface) const
+{
+  const nsIID* piid;
+
+  switch (mType) {
+    case nsIDataType::VTYPE_INTERFACE:
+      piid = &NS_GET_IID(nsISupports);
+      break;
+    case nsIDataType::VTYPE_INTERFACE_IS:
+      piid = &u.iface.mInterfaceID;
+      break;
+    default:
+      return NS_ERROR_CANNOT_CONVERT_DATA;
+  }
+
+  *aIID = (nsIID*)nsMemory::Clone(piid, sizeof(nsIID));
+  if (!*aIID) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  if (u.iface.mInterfaceValue) {
+    return u.iface.mInterfaceValue->QueryInterface(*piid, aInterface);
+  }
+
+  *aInterface = nullptr;
+  return NS_OK;
+}
+
+nsresult
+nsDiscriminatedUnion::ConvertToArray(uint16_t* aType, nsIID* aIID,
+                                     uint32_t* aCount, void** aPtr) const
+{
+  // XXX perhaps we'd like to add support for converting each of the various
+  // types into an array containing one element of that type. We can leverage
+  // CloneArray to do this if we want to support this.
+
+  if (mType == nsIDataType::VTYPE_ARRAY) {
+    return CloneArray(u.array.mArrayType, &u.array.mArrayInterfaceID,
+                      u.array.mArrayCount, u.array.mArrayValue,
+                      aType, aIID, aCount, aPtr);
+  }
+  return NS_ERROR_CANNOT_CONVERT_DATA;
+}
+
+/***************************************************************************/
+// static setter functions...
+
+#define DATA_SETTER_PROLOGUE                                                  \
+    Cleanup()
+
+#define DATA_SETTER_EPILOGUE(type_)                                           \
+    mType = nsIDataType::type_;
+
+#define DATA_SETTER(type_, member_, value_)                                   \
+    DATA_SETTER_PROLOGUE;                                                     \
+    u.member_ = value_;                                                       \
+    DATA_SETTER_EPILOGUE(type_)
+
+#define DATA_SETTER_WITH_CAST(type_, member_, cast_, value_)                  \
+    DATA_SETTER_PROLOGUE;                                                     \
+    u.member_ = cast_ value_;                                                 \
+    DATA_SETTER_EPILOGUE(type_)
+
+
+/********************************************/
+
+#define CASE__SET_FROM_VARIANT_VTYPE_PROLOGUE(type_)                          \
+    {                                                                         \
+
+#define CASE__SET_FROM_VARIANT_VTYPE__GETTER(member_, name_)                  \
+        rv = aValue->GetAs##name_ (&(u.member_ ));
+
+#define CASE__SET_FROM_VARIANT_VTYPE__GETTER_CAST(cast_, member_, name_)      \
+        rv = aValue->GetAs##name_ ( cast_ &(u.member_ ));
+
+#define CASE__SET_FROM_VARIANT_VTYPE_EPILOGUE(type_)                          \
+        if (NS_SUCCEEDED(rv)) {                                               \
+          mType  = nsIDataType::type_ ;                                       \
+        }                                                                     \
+        break;                                                                \
+    }
+
+#define CASE__SET_FROM_VARIANT_TYPE(type_, member_, name_)                    \
+    case nsIDataType::type_:                                                  \
+        CASE__SET_FROM_VARIANT_VTYPE_PROLOGUE(type_)                          \
+        CASE__SET_FROM_VARIANT_VTYPE__GETTER(member_, name_)                  \
+        CASE__SET_FROM_VARIANT_VTYPE_EPILOGUE(type_)
+
+#define CASE__SET_FROM_VARIANT_VTYPE_CAST(type_, cast_, member_, name_)       \
+    case nsIDataType::type_ :                                                 \
+        CASE__SET_FROM_VARIANT_VTYPE_PROLOGUE(type_)                          \
+        CASE__SET_FROM_VARIANT_VTYPE__GETTER_CAST(cast_, member_, name_)      \
+        CASE__SET_FROM_VARIANT_VTYPE_EPILOGUE(type_)
+
+
+nsresult
+nsDiscriminatedUnion::SetFromVariant(nsIVariant* aValue)
+{
+  uint16_t type;
+  nsresult rv;
+
+  Cleanup();
+
+  rv = aValue->GetDataType(&type);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  switch (type) {
+    CASE__SET_FROM_VARIANT_VTYPE_CAST(VTYPE_INT8, (uint8_t*), mInt8Value,
+                                      Int8)
+    CASE__SET_FROM_VARIANT_TYPE(VTYPE_INT16,  mInt16Value,  Int16)
+    CASE__SET_FROM_VARIANT_TYPE(VTYPE_INT32,  mInt32Value,  Int32)
+    CASE__SET_FROM_VARIANT_TYPE(VTYPE_UINT8,  mUint8Value,  Uint8)
+    CASE__SET_FROM_VARIANT_TYPE(VTYPE_UINT16, mUint16Value, Uint16)
+    CASE__SET_FROM_VARIANT_TYPE(VTYPE_UINT32, mUint32Value, Uint32)
+    CASE__SET_FROM_VARIANT_TYPE(VTYPE_FLOAT,  mFloatValue,  Float)
+    CASE__SET_FROM_VARIANT_TYPE(VTYPE_DOUBLE, mDoubleValue, Double)
+    CASE__SET_FROM_VARIANT_TYPE(VTYPE_BOOL ,  mBoolValue,   Bool)
+    CASE__SET_FROM_VARIANT_TYPE(VTYPE_CHAR,   mCharValue,   Char)
+    CASE__SET_FROM_VARIANT_TYPE(VTYPE_WCHAR,  mWCharValue,  WChar)
+    CASE__SET_FROM_VARIANT_TYPE(VTYPE_ID,     mIDValue,     ID)
+
+    case nsIDataType::VTYPE_ASTRING:
+    case nsIDataType::VTYPE_DOMSTRING:
+    case nsIDataType::VTYPE_WCHAR_STR:
+    case nsIDataType::VTYPE_WSTRING_SIZE_IS:
+      CASE__SET_FROM_VARIANT_VTYPE_PROLOGUE(VTYPE_ASTRING);
+      u.mAStringValue = new nsString();
+      if (!u.mAStringValue) {
+        return NS_ERROR_OUT_OF_MEMORY;
+      }
+      rv = aValue->GetAsAString(*u.mAStringValue);
+      if (NS_FAILED(rv)) {
+        delete u.mAStringValue;
+      }
+      CASE__SET_FROM_VARIANT_VTYPE_EPILOGUE(VTYPE_ASTRING)
+
+    case nsIDataType::VTYPE_CSTRING:
+      CASE__SET_FROM_VARIANT_VTYPE_PROLOGUE(VTYPE_CSTRING);
+      u.mCStringValue = new nsCString();
+      if (!u.mCStringValue) {
+        return NS_ERROR_OUT_OF_MEMORY;
+      }
+      rv = aValue->GetAsACString(*u.mCStringValue);
+      if (NS_FAILED(rv)) {
+        delete u.mCStringValue;
+      }
+      CASE__SET_FROM_VARIANT_VTYPE_EPILOGUE(VTYPE_CSTRING)
+
+    case nsIDataType::VTYPE_UTF8STRING:
+      CASE__SET_FROM_VARIANT_VTYPE_PROLOGUE(VTYPE_UTF8STRING);
+      u.mUTF8StringValue = new nsUTF8String();
+      if (!u.mUTF8StringValue) {
+        return NS_ERROR_OUT_OF_MEMORY;
+      }
+      rv = aValue->GetAsAUTF8String(*u.mUTF8StringValue);
+      if (NS_FAILED(rv)) {
+        delete u.mUTF8StringValue;
+      }
+      CASE__SET_FROM_VARIANT_VTYPE_EPILOGUE(VTYPE_UTF8STRING)
+
+    case nsIDataType::VTYPE_CHAR_STR:
+    case nsIDataType::VTYPE_STRING_SIZE_IS:
+      CASE__SET_FROM_VARIANT_VTYPE_PROLOGUE(VTYPE_STRING_SIZE_IS);
+      rv = aValue->GetAsStringWithSize(&u.str.mStringLength,
+                                       &u.str.mStringValue);
+      CASE__SET_FROM_VARIANT_VTYPE_EPILOGUE(VTYPE_STRING_SIZE_IS)
+
+    case nsIDataType::VTYPE_INTERFACE:
+    case nsIDataType::VTYPE_INTERFACE_IS:
+      CASE__SET_FROM_VARIANT_VTYPE_PROLOGUE(VTYPE_INTERFACE_IS);
+      // XXX This iid handling is ugly!
+      nsIID* iid;
+      rv = aValue->GetAsInterface(&iid, (void**)&u.iface.mInterfaceValue);
+      if (NS_SUCCEEDED(rv)) {
+        u.iface.mInterfaceID = *iid;
+        free((char*)iid);
+      }
+      CASE__SET_FROM_VARIANT_VTYPE_EPILOGUE(VTYPE_INTERFACE_IS)
+
+    case nsIDataType::VTYPE_ARRAY:
+      CASE__SET_FROM_VARIANT_VTYPE_PROLOGUE(VTYPE_ARRAY);
+      rv = aValue->GetAsArray(&u.array.mArrayType,
+                              &u.array.mArrayInterfaceID,
+                              &u.array.mArrayCount,
+                              &u.array.mArrayValue);
+      CASE__SET_FROM_VARIANT_VTYPE_EPILOGUE(VTYPE_ARRAY)
+
+    case nsIDataType::VTYPE_VOID:
+      SetToVoid();
+      rv = NS_OK;
+      break;
+    case nsIDataType::VTYPE_EMPTY_ARRAY:
+      SetToEmptyArray();
+      rv = NS_OK;
+      break;
+    case nsIDataType::VTYPE_EMPTY:
+      SetToEmpty();
+      rv = NS_OK;
+      break;
+    default:
+      NS_ERROR("bad type in variant!");
+      rv = NS_ERROR_FAILURE;
+      break;
+  }
+  return rv;
+}
+
+void
+nsDiscriminatedUnion::SetFromInt8(uint8_t aValue)
+{
+  DATA_SETTER_WITH_CAST(VTYPE_INT8, mInt8Value, (uint8_t), aValue);
+}
+void
+nsDiscriminatedUnion::SetFromInt16(int16_t aValue)
+{
+  DATA_SETTER(VTYPE_INT16, mInt16Value, aValue);
+}
+void
+nsDiscriminatedUnion::SetFromInt32(int32_t aValue)
+{
+  DATA_SETTER(VTYPE_INT32, mInt32Value, aValue);
+}
+void
+nsDiscriminatedUnion::SetFromInt64(int64_t aValue)
+{
+  DATA_SETTER(VTYPE_INT64, mInt64Value, aValue);
+}
+void
+nsDiscriminatedUnion::SetFromUint8(uint8_t aValue)
+{
+  DATA_SETTER(VTYPE_UINT8, mUint8Value, aValue);
+}
+void
+nsDiscriminatedUnion::SetFromUint16(uint16_t aValue)
+{
+  DATA_SETTER(VTYPE_UINT16, mUint16Value, aValue);
+}
+void
+nsDiscriminatedUnion::SetFromUint32(uint32_t aValue)
+{
+  DATA_SETTER(VTYPE_UINT32, mUint32Value, aValue);
+}
+void
+nsDiscriminatedUnion::SetFromUint64(uint64_t aValue)
+{
+  DATA_SETTER(VTYPE_UINT64, mUint64Value, aValue);
+}
+void
+nsDiscriminatedUnion::SetFromFloat(float aValue)
+{
+  DATA_SETTER(VTYPE_FLOAT, mFloatValue, aValue);
+}
+void
+nsDiscriminatedUnion::SetFromDouble(double aValue)
+{
+  DATA_SETTER(VTYPE_DOUBLE, mDoubleValue, aValue);
+}
+void
+nsDiscriminatedUnion::SetFromBool(bool aValue)
+{
+  DATA_SETTER(VTYPE_BOOL, mBoolValue, aValue);
+}
+void
+nsDiscriminatedUnion::SetFromChar(char aValue)
+{
+  DATA_SETTER(VTYPE_CHAR, mCharValue, aValue);
+}
+void
+nsDiscriminatedUnion::SetFromWChar(char16_t aValue)
+{
+  DATA_SETTER(VTYPE_WCHAR, mWCharValue, aValue);
+}
+void
+nsDiscriminatedUnion::SetFromID(const nsID& aValue)
+{
+  DATA_SETTER(VTYPE_ID, mIDValue, aValue);
+}
+void
+nsDiscriminatedUnion::SetFromAString(const nsAString& aValue)
+{
+  DATA_SETTER_PROLOGUE;
+  u.mAStringValue = new nsString(aValue);
+  DATA_SETTER_EPILOGUE(VTYPE_ASTRING);
+}
+
+void
+nsDiscriminatedUnion::SetFromDOMString(const nsAString& aValue)
+{
+  DATA_SETTER_PROLOGUE;
+  u.mAStringValue = new nsString(aValue);
+  DATA_SETTER_EPILOGUE(VTYPE_DOMSTRING);
+}
+
+void
+nsDiscriminatedUnion::SetFromACString(const nsACString& aValue)
+{
+  DATA_SETTER_PROLOGUE;
+  u.mCStringValue = new nsCString(aValue);
+  DATA_SETTER_EPILOGUE(VTYPE_CSTRING);
+}
+
+void
+nsDiscriminatedUnion::SetFromAUTF8String(const nsAUTF8String& aValue)
+{
+  DATA_SETTER_PROLOGUE;
+  u.mUTF8StringValue = new nsUTF8String(aValue);
+  DATA_SETTER_EPILOGUE(VTYPE_UTF8STRING);
+}
+
+nsresult
+nsDiscriminatedUnion::SetFromString(const char* aValue)
+{
+  DATA_SETTER_PROLOGUE;
+  if (!aValue) {
+    return NS_ERROR_NULL_POINTER;
+  }
+  return SetFromStringWithSize(strlen(aValue), aValue);
+}
+nsresult
+nsDiscriminatedUnion::SetFromWString(const char16_t* aValue)
+{
+  DATA_SETTER_PROLOGUE;
+  if (!aValue) {
+    return NS_ERROR_NULL_POINTER;
+  }
+  return SetFromWStringWithSize(NS_strlen(aValue), aValue);
+}
+void
+nsDiscriminatedUnion::SetFromISupports(nsISupports* aValue)
+{
+  return SetFromInterface(NS_GET_IID(nsISupports), aValue);
+}
+void
+nsDiscriminatedUnion::SetFromInterface(const nsIID& aIID, nsISupports* aValue)
+{
+  DATA_SETTER_PROLOGUE;
+  NS_IF_ADDREF(aValue);
+  u.iface.mInterfaceValue = aValue;
+  u.iface.mInterfaceID = aIID;
+  DATA_SETTER_EPILOGUE(VTYPE_INTERFACE_IS);
+}
+nsresult
+nsDiscriminatedUnion::SetFromArray(uint16_t aType, const nsIID* aIID,
+                                   uint32_t aCount, void* aValue)
+{
+  DATA_SETTER_PROLOGUE;
+  if (!aValue || !aCount) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  nsresult rv = CloneArray(aType, aIID, aCount, aValue,
+                           &u.array.mArrayType,
+                           &u.array.mArrayInterfaceID,
+                           &u.array.mArrayCount,
+                           &u.array.mArrayValue);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  DATA_SETTER_EPILOGUE(VTYPE_ARRAY);
+  return NS_OK;
+}
+nsresult
+nsDiscriminatedUnion::SetFromStringWithSize(uint32_t aSize,
+                                            const char* aValue)
+{
+  DATA_SETTER_PROLOGUE;
+  if (!aValue) {
+    return NS_ERROR_NULL_POINTER;
+  }
+  if (!(u.str.mStringValue =
+        (char*)nsMemory::Clone(aValue, (aSize + 1) * sizeof(char)))) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  u.str.mStringLength = aSize;
+  DATA_SETTER_EPILOGUE(VTYPE_STRING_SIZE_IS);
+  return NS_OK;
+}
+nsresult
+nsDiscriminatedUnion::SetFromWStringWithSize(uint32_t aSize,
+                                             const char16_t* aValue)
+{
+  DATA_SETTER_PROLOGUE;
+  if (!aValue) {
+    return NS_ERROR_NULL_POINTER;
+  }
+  if (!(u.wstr.mWStringValue =
+        (char16_t*)nsMemory::Clone(aValue, (aSize + 1) * sizeof(char16_t)))) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  u.wstr.mWStringLength = aSize;
+  DATA_SETTER_EPILOGUE(VTYPE_WSTRING_SIZE_IS);
+  return NS_OK;
+}
+void
+nsDiscriminatedUnion::AllocateWStringWithSize(uint32_t aSize)
+{
+  DATA_SETTER_PROLOGUE;
+  u.wstr.mWStringValue = (char16_t*)moz_xmalloc((aSize + 1) * sizeof(char16_t));
+  u.wstr.mWStringValue[aSize] = '\0';
+  u.wstr.mWStringLength = aSize;
+  DATA_SETTER_EPILOGUE(VTYPE_WSTRING_SIZE_IS);
+}
+void
+nsDiscriminatedUnion::SetToVoid()
+{
+  DATA_SETTER_PROLOGUE;
+  DATA_SETTER_EPILOGUE(VTYPE_VOID);
+}
+void
+nsDiscriminatedUnion::SetToEmpty()
+{
+  DATA_SETTER_PROLOGUE;
+  DATA_SETTER_EPILOGUE(VTYPE_EMPTY);
+}
+void
+nsDiscriminatedUnion::SetToEmptyArray()
+{
+  DATA_SETTER_PROLOGUE;
+  DATA_SETTER_EPILOGUE(VTYPE_EMPTY_ARRAY);
+}
+
+/***************************************************************************/
+
+void
+nsDiscriminatedUnion::Cleanup()
+{
+  switch (mType) {
+    case nsIDataType::VTYPE_INT8:
+    case nsIDataType::VTYPE_INT16:
+    case nsIDataType::VTYPE_INT32:
+    case nsIDataType::VTYPE_INT64:
+    case nsIDataType::VTYPE_UINT8:
+    case nsIDataType::VTYPE_UINT16:
+    case nsIDataType::VTYPE_UINT32:
+    case nsIDataType::VTYPE_UINT64:
+    case nsIDataType::VTYPE_FLOAT:
+    case nsIDataType::VTYPE_DOUBLE:
+    case nsIDataType::VTYPE_BOOL:
+    case nsIDataType::VTYPE_CHAR:
+    case nsIDataType::VTYPE_WCHAR:
+    case nsIDataType::VTYPE_VOID:
+    case nsIDataType::VTYPE_ID:
+      break;
+    case nsIDataType::VTYPE_ASTRING:
+    case nsIDataType::VTYPE_DOMSTRING:
+      delete u.mAStringValue;
+      break;
+    case nsIDataType::VTYPE_CSTRING:
+      delete u.mCStringValue;
+      break;
+    case nsIDataType::VTYPE_UTF8STRING:
+      delete u.mUTF8StringValue;
+      break;
+    case nsIDataType::VTYPE_CHAR_STR:
+    case nsIDataType::VTYPE_STRING_SIZE_IS:
+      free((char*)u.str.mStringValue);
+      break;
+    case nsIDataType::VTYPE_WCHAR_STR:
+    case nsIDataType::VTYPE_WSTRING_SIZE_IS:
+      free((char*)u.wstr.mWStringValue);
+      break;
+    case nsIDataType::VTYPE_INTERFACE:
+    case nsIDataType::VTYPE_INTERFACE_IS:
+      NS_IF_RELEASE(u.iface.mInterfaceValue);
+      break;
+    case nsIDataType::VTYPE_ARRAY:
+      FreeArray();
+      break;
+    case nsIDataType::VTYPE_EMPTY_ARRAY:
+    case nsIDataType::VTYPE_EMPTY:
+      break;
+    default:
+      NS_ERROR("bad type in variant!");
+      break;
+  }
+
+  mType = nsIDataType::VTYPE_EMPTY;
+}
+
+void
+nsDiscriminatedUnion::Traverse(nsCycleCollectionTraversalCallback& aCb) const
+{
+  switch (mType) {
+    case nsIDataType::VTYPE_INTERFACE:
+    case nsIDataType::VTYPE_INTERFACE_IS:
+      NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(aCb, "mData");
+      aCb.NoteXPCOMChild(u.iface.mInterfaceValue);
+      break;
+    case nsIDataType::VTYPE_ARRAY:
+      switch (u.array.mArrayType) {
+        case nsIDataType::VTYPE_INTERFACE:
+        case nsIDataType::VTYPE_INTERFACE_IS: {
+          nsISupports** p = (nsISupports**)u.array.mArrayValue;
+          for (uint32_t i = u.array.mArrayCount; i > 0; ++p, --i) {
+            NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(aCb, "mData[i]");
+            aCb.NoteXPCOMChild(*p);
+          }
+          break;
+        }
+        default:
+          break;
+      }
+      break;
+    default:
+      break;
+  }
+}
+
+/***************************************************************************/
+/***************************************************************************/
+// members...
+
+nsVariantBase::nsVariantBase()
+  : mWritable(true)
+{
+#ifdef DEBUG
+  {
+    // Assert that the nsIDataType consts match the values #defined in
+    // xpt_struct.h. Bad things happen somewhere if they don't.
+    struct THE_TYPES
+    {
+      uint16_t a;
+      uint16_t b;
+    };
+    static const THE_TYPES array[] = {
+      {nsIDataType::VTYPE_INT8              , TD_INT8             },
+      {nsIDataType::VTYPE_INT16             , TD_INT16            },
+      {nsIDataType::VTYPE_INT32             , TD_INT32            },
+      {nsIDataType::VTYPE_INT64             , TD_INT64            },
+      {nsIDataType::VTYPE_UINT8             , TD_UINT8            },
+      {nsIDataType::VTYPE_UINT16            , TD_UINT16           },
+      {nsIDataType::VTYPE_UINT32            , TD_UINT32           },
+      {nsIDataType::VTYPE_UINT64            , TD_UINT64           },
+      {nsIDataType::VTYPE_FLOAT             , TD_FLOAT            },
+      {nsIDataType::VTYPE_DOUBLE            , TD_DOUBLE           },
+      {nsIDataType::VTYPE_BOOL              , TD_BOOL             },
+      {nsIDataType::VTYPE_CHAR              , TD_CHAR             },
+      {nsIDataType::VTYPE_WCHAR             , TD_WCHAR            },
+      {nsIDataType::VTYPE_VOID              , TD_VOID             },
+      {nsIDataType::VTYPE_ID                , TD_PNSIID           },
+      {nsIDataType::VTYPE_DOMSTRING         , TD_DOMSTRING        },
+      {nsIDataType::VTYPE_CHAR_STR          , TD_PSTRING          },
+      {nsIDataType::VTYPE_WCHAR_STR         , TD_PWSTRING         },
+      {nsIDataType::VTYPE_INTERFACE         , TD_INTERFACE_TYPE   },
+      {nsIDataType::VTYPE_INTERFACE_IS      , TD_INTERFACE_IS_TYPE},
+      {nsIDataType::VTYPE_ARRAY             , TD_ARRAY            },
+      {nsIDataType::VTYPE_STRING_SIZE_IS    , TD_PSTRING_SIZE_IS  },
+      {nsIDataType::VTYPE_WSTRING_SIZE_IS   , TD_PWSTRING_SIZE_IS },
+      {nsIDataType::VTYPE_UTF8STRING        , TD_UTF8STRING       },
+      {nsIDataType::VTYPE_CSTRING           , TD_CSTRING          },
+      {nsIDataType::VTYPE_ASTRING           , TD_ASTRING          }
+    };
+    static const int length = sizeof(array) / sizeof(array[0]);
+    static bool inited = false;
+    if (!inited) {
+      for (int i = 0; i < length; ++i) {
+        NS_ASSERTION(array[i].a == array[i].b, "bad const declaration");
+      }
+      inited = true;
+    }
+  }
+#endif
+}
+
+// For all the data getters we just forward to the static (and sharable)
+// 'ConvertTo' functions.
+
+NS_IMETHODIMP
+nsVariantBase::GetDataType(uint16_t* aDataType)
+{
+  *aDataType = mData.GetType();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsInt8(uint8_t* aResult)
+{
+  return mData.ConvertToInt8(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsInt16(int16_t* aResult)
+{
+  return mData.ConvertToInt16(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsInt32(int32_t* aResult)
+{
+  return mData.ConvertToInt32(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsInt64(int64_t* aResult)
+{
+  return mData.ConvertToInt64(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsUint8(uint8_t* aResult)
+{
+  return mData.ConvertToUint8(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsUint16(uint16_t* aResult)
+{
+  return mData.ConvertToUint16(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsUint32(uint32_t* aResult)
+{
+  return mData.ConvertToUint32(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsUint64(uint64_t* aResult)
+{
+  return mData.ConvertToUint64(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsFloat(float* aResult)
+{
+  return mData.ConvertToFloat(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsDouble(double* aResult)
+{
+  return mData.ConvertToDouble(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsBool(bool* aResult)
+{
+  return mData.ConvertToBool(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsChar(char* aResult)
+{
+  return mData.ConvertToChar(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsWChar(char16_t* aResult)
+{
+  return mData.ConvertToWChar(aResult);
+}
+
+NS_IMETHODIMP_(nsresult)
+nsVariantBase::GetAsID(nsID* aResult)
+{
+  return mData.ConvertToID(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsAString(nsAString& aResult)
+{
+  return mData.ConvertToAString(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsDOMString(nsAString& aResult)
+{
+  // A DOMString maps to an AString internally, so we can re-use
+  // ConvertToAString here.
+  return mData.ConvertToAString(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsACString(nsACString& aResult)
+{
+  return mData.ConvertToACString(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsAUTF8String(nsAUTF8String& aResult)
+{
+  return mData.ConvertToAUTF8String(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsString(char** aResult)
+{
+  return mData.ConvertToString(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsWString(char16_t** aResult)
+{
+  return mData.ConvertToWString(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsISupports(nsISupports** aResult)
+{
+  return mData.ConvertToISupports(aResult);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsJSVal(JS::MutableHandleValue)
+{
+  // Can only get the jsval from an XPCVariant.
+  return NS_ERROR_CANNOT_CONVERT_DATA;
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsInterface(nsIID** aIID, void** aInterface)
+{
+  return mData.ConvertToInterface(aIID, aInterface);
+}
+
+NS_IMETHODIMP_(nsresult)
+nsVariantBase::GetAsArray(uint16_t* aType, nsIID* aIID,
+                      uint32_t* aCount, void** aPtr)
+{
+  return mData.ConvertToArray(aType, aIID, aCount, aPtr);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsStringWithSize(uint32_t* aSize, char** aStr)
+{
+  return mData.ConvertToStringWithSize(aSize, aStr);
+}
+
+NS_IMETHODIMP
+nsVariantBase::GetAsWStringWithSize(uint32_t* aSize, char16_t** aStr)
+{
+  return mData.ConvertToWStringWithSize(aSize, aStr);
+}
+
+/***************************************************************************/
+
+NS_IMETHODIMP
+nsVariantBase::GetWritable(bool* aWritable)
+{
+  *aWritable = mWritable;
+  return NS_OK;
+}
+NS_IMETHODIMP
+nsVariantBase::SetWritable(bool aWritable)
+{
+  if (!mWritable && aWritable) {
+    return NS_ERROR_FAILURE;
+  }
+  mWritable = aWritable;
+  return NS_OK;
+}
+
+/***************************************************************************/
+
+// For all the data setters we just forward to the static (and sharable)
+// 'SetFrom' functions.
+
+NS_IMETHODIMP
+nsVariantBase::SetAsInt8(uint8_t aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromInt8(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsInt16(int16_t aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromInt16(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsInt32(int32_t aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromInt32(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsInt64(int64_t aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromInt64(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsUint8(uint8_t aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromUint8(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsUint16(uint16_t aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromUint16(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsUint32(uint32_t aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromUint32(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsUint64(uint64_t aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromUint64(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsFloat(float aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromFloat(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsDouble(double aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromDouble(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsBool(bool aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromBool(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsChar(char aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromChar(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsWChar(char16_t aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromWChar(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsID(const nsID& aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromID(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsAString(const nsAString& aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromAString(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsDOMString(const nsAString& aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+
+  mData.SetFromDOMString(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsACString(const nsACString& aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromACString(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsAUTF8String(const nsAUTF8String& aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromAUTF8String(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsString(const char* aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  return mData.SetFromString(aValue);
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsWString(const char16_t* aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  return mData.SetFromWString(aValue);
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsISupports(nsISupports* aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromISupports(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsInterface(const nsIID& aIID, void* aInterface)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetFromInterface(aIID, (nsISupports*)aInterface);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsArray(uint16_t aType, const nsIID* aIID,
+                      uint32_t aCount, void* aPtr)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  return mData.SetFromArray(aType, aIID, aCount, aPtr);
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsStringWithSize(uint32_t aSize, const char* aStr)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  return mData.SetFromStringWithSize(aSize, aStr);
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsWStringWithSize(uint32_t aSize, const char16_t* aStr)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  return mData.SetFromWStringWithSize(aSize, aStr);
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsVoid()
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetToVoid();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsEmpty()
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetToEmpty();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetAsEmptyArray()
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  mData.SetToEmptyArray();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsVariantBase::SetFromVariant(nsIVariant* aValue)
+{
+  if (!mWritable) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+  return mData.SetFromVariant(aValue);
+}
+
+/* nsVariant implementation */
+
+NS_IMPL_ISUPPORTS(nsVariant, nsIVariant, nsIWritableVariant)
+
+
+/* nsVariantCC implementation */
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsVariantCC)
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+  NS_INTERFACE_MAP_ENTRY(nsIVariant)
+  NS_INTERFACE_MAP_ENTRY(nsIWritableVariant)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(nsVariantCC)
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(nsVariantCC)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(nsVariantCC)
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsVariantCC)
+  tmp->mData.Traverse(cb);
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsVariantCC)
+  tmp->mData.Cleanup();
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
diff --git a/xpcom/ds/nsVariant.h b/xpcom/ds/nsVariant.h
new file mode 100644
index 000000000..5be2d18ee
--- /dev/null
+++ b/xpcom/ds/nsVariant.h
@@ -0,0 +1,229 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsVariant_h
+#define nsVariant_h
+
+#include "nsIVariant.h"
+#include "nsStringFwd.h"
+#include "mozilla/Attributes.h"
+#include "nsCycleCollectionParticipant.h"
+
+/**
+ * Map the nsAUTF8String, nsUTF8String classes to the nsACString and
+ * nsCString classes respectively for now.  These defines need to be removed
+ * once Jag lands his nsUTF8String implementation.
+ */
+#define nsAUTF8String nsACString
+#define nsUTF8String nsCString
+#define PromiseFlatUTF8String PromiseFlatCString
+
+/**
+ * nsDiscriminatedUnion is a class that nsIVariant implementors can use
+ * to hold the underlying data.
+ */
+
+class nsDiscriminatedUnion
+{
+public:
+
+  nsDiscriminatedUnion() : mType(nsIDataType::VTYPE_EMPTY) {}
+  nsDiscriminatedUnion(const nsDiscriminatedUnion&) = delete;
+  nsDiscriminatedUnion(nsDiscriminatedUnion&&) = delete;
+
+  ~nsDiscriminatedUnion() { Cleanup(); }
+
+  nsDiscriminatedUnion& operator=(const nsDiscriminatedUnion&) = delete;
+  nsDiscriminatedUnion& operator=(nsDiscriminatedUnion&&) = delete;
+
+  void Cleanup();
+
+  uint16_t GetType() const { return mType; }
+
+  MOZ_MUST_USE nsresult ConvertToInt8(uint8_t* aResult) const;
+  MOZ_MUST_USE nsresult ConvertToInt16(int16_t* aResult) const;
+  MOZ_MUST_USE nsresult ConvertToInt32(int32_t* aResult) const;
+  MOZ_MUST_USE nsresult ConvertToInt64(int64_t* aResult) const;
+  MOZ_MUST_USE nsresult ConvertToUint8(uint8_t* aResult) const;
+  MOZ_MUST_USE nsresult ConvertToUint16(uint16_t* aResult) const;
+  MOZ_MUST_USE nsresult ConvertToUint32(uint32_t* aResult) const;
+  MOZ_MUST_USE nsresult ConvertToUint64(uint64_t* aResult) const;
+  MOZ_MUST_USE nsresult ConvertToFloat(float* aResult) const;
+  MOZ_MUST_USE nsresult ConvertToDouble(double* aResult) const;
+  MOZ_MUST_USE nsresult ConvertToBool(bool* aResult) const;
+  MOZ_MUST_USE nsresult ConvertToChar(char* aResult) const;
+  MOZ_MUST_USE nsresult ConvertToWChar(char16_t* aResult) const;
+
+  MOZ_MUST_USE nsresult ConvertToID(nsID* aResult) const;
+
+  MOZ_MUST_USE nsresult ConvertToAString(nsAString& aResult) const;
+  MOZ_MUST_USE nsresult ConvertToAUTF8String(nsAUTF8String& aResult) const;
+  MOZ_MUST_USE nsresult ConvertToACString(nsACString& aResult) const;
+  MOZ_MUST_USE nsresult ConvertToString(char** aResult) const;
+  MOZ_MUST_USE nsresult ConvertToWString(char16_t** aResult) const;
+  MOZ_MUST_USE nsresult ConvertToStringWithSize(uint32_t* aSize, char** aStr) const;
+  MOZ_MUST_USE nsresult ConvertToWStringWithSize(uint32_t* aSize, char16_t** aStr) const;
+
+  MOZ_MUST_USE nsresult ConvertToISupports(nsISupports** aResult) const;
+  MOZ_MUST_USE nsresult ConvertToInterface(nsIID** aIID, void** aInterface) const;
+  MOZ_MUST_USE nsresult ConvertToArray(uint16_t* aType, nsIID* aIID,
+                                       uint32_t* aCount, void** aPtr) const;
+
+  MOZ_MUST_USE nsresult SetFromVariant(nsIVariant* aValue);
+
+  void SetFromInt8(uint8_t aValue);
+  void SetFromInt16(int16_t aValue);
+  void SetFromInt32(int32_t aValue);
+  void SetFromInt64(int64_t aValue);
+  void SetFromUint8(uint8_t aValue);
+  void SetFromUint16(uint16_t aValue);
+  void SetFromUint32(uint32_t aValue);
+  void SetFromUint64(uint64_t aValue);
+  void SetFromFloat(float aValue);
+  void SetFromDouble(double aValue);
+  void SetFromBool(bool aValue);
+  void SetFromChar(char aValue);
+  void SetFromWChar(char16_t aValue);
+  void SetFromID(const nsID& aValue);
+  void SetFromAString(const nsAString& aValue);
+  void SetFromDOMString(const nsAString& aValue);
+  void SetFromAUTF8String(const nsAUTF8String& aValue);
+  void SetFromACString(const nsACString& aValue);
+  MOZ_MUST_USE nsresult SetFromString(const char* aValue);
+  MOZ_MUST_USE nsresult SetFromWString(const char16_t* aValue);
+  void SetFromISupports(nsISupports* aValue);
+  void SetFromInterface(const nsIID& aIID, nsISupports* aValue);
+  MOZ_MUST_USE nsresult SetFromArray(uint16_t aType, const nsIID* aIID,
+                                     uint32_t aCount, void* aValue);
+  MOZ_MUST_USE nsresult SetFromStringWithSize(uint32_t aSize,
+                                              const char* aValue);
+  MOZ_MUST_USE nsresult SetFromWStringWithSize(uint32_t aSize,
+                                               const char16_t* aValue);
+
+  // Like SetFromWStringWithSize, but leaves the string uninitialized. It does
+  // does write the null-terminator.
+  void AllocateWStringWithSize(uint32_t aSize);
+
+  void SetToVoid();
+  void SetToEmpty();
+  void SetToEmptyArray();
+
+  void Traverse(nsCycleCollectionTraversalCallback& aCb) const;
+
+private:
+  MOZ_MUST_USE nsresult
+  ToManageableNumber(nsDiscriminatedUnion* aOutData) const;
+  void FreeArray();
+  MOZ_MUST_USE bool String2ID(nsID* aPid) const;
+  MOZ_MUST_USE nsresult ToString(nsACString& aOutString) const;
+
+public:
+  union
+  {
+    int8_t         mInt8Value;
+    int16_t        mInt16Value;
+    int32_t        mInt32Value;
+    int64_t        mInt64Value;
+    uint8_t        mUint8Value;
+    uint16_t       mUint16Value;
+    uint32_t       mUint32Value;
+    uint64_t       mUint64Value;
+    float          mFloatValue;
+    double         mDoubleValue;
+    bool           mBoolValue;
+    char           mCharValue;
+    char16_t       mWCharValue;
+    nsIID          mIDValue;
+    nsAString*     mAStringValue;
+    nsAUTF8String* mUTF8StringValue;
+    nsACString*    mCStringValue;
+    struct
+    {
+      // This is an owning reference that cannot be an nsCOMPtr because
+      // nsDiscriminatedUnion needs to be POD.  AddRef/Release are manually
+      // called on this.
+      nsISupports* MOZ_OWNING_REF mInterfaceValue;
+      nsIID        mInterfaceID;
+    } iface;
+    struct
+    {
+      nsIID        mArrayInterfaceID;
+      void*        mArrayValue;
+      uint32_t     mArrayCount;
+      uint16_t     mArrayType;
+    } array;
+    struct
+    {
+      char*        mStringValue;
+      uint32_t     mStringLength;
+    } str;
+    struct
+    {
+      char16_t*    mWStringValue;
+      uint32_t     mWStringLength;
+    } wstr;
+  } u;
+  uint16_t       mType;
+};
+
+/**
+ * nsVariant implements the generic variant support. The xpcom module registers
+ * a factory (see NS_VARIANT_CONTRACTID in nsIVariant.idl) that will create
+ * these objects. They are created 'empty' and 'writable'.
+ *
+ * nsIVariant users won't usually need to see this class.
+ */
+class nsVariantBase : public nsIWritableVariant
+{
+public:
+  NS_DECL_NSIVARIANT
+  NS_DECL_NSIWRITABLEVARIANT
+
+  nsVariantBase();
+
+protected:
+  ~nsVariantBase() {};
+
+  nsDiscriminatedUnion mData;
+  bool mWritable;
+};
+
+class nsVariant final : public nsVariantBase
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  nsVariant() {};
+
+private:
+  ~nsVariant() {};
+};
+
+class nsVariantCC final : public nsVariantBase
+{
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_CLASS(nsVariantCC)
+
+  nsVariantCC() {};
+
+private:
+  ~nsVariantCC() {};
+};
+
+/**
+ * Users of nsIVariant should be using the contractID and not this CID.
+ *  - see NS_VARIANT_CONTRACTID in nsIVariant.idl.
+ */
+
+#define NS_VARIANT_CID \
+{ /* 0D6EA1D0-879C-11d5-90EF-0010A4E73D9A */ \
+    0xd6ea1d0,                               \
+    0x879c,                                  \
+    0x11d5,                                  \
+    {0x90, 0xef, 0x0, 0x10, 0xa4, 0xe7, 0x3d, 0x9a}}
+
+#endif // nsVariant_h
diff --git a/xpcom/ds/nsWhitespaceTokenizer.h b/xpcom/ds/nsWhitespaceTokenizer.h
new file mode 100644
index 000000000..bfe32f8dc
--- /dev/null
+++ b/xpcom/ds/nsWhitespaceTokenizer.h
@@ -0,0 +1,110 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __nsWhitespaceTokenizer_h
+#define __nsWhitespaceTokenizer_h
+
+#include "mozilla/RangedPtr.h"
+#include "nsDependentSubstring.h"
+#include "nsCRT.h"
+
+template<typename DependentSubstringType, bool IsWhitespace(char16_t)>
+class nsTWhitespaceTokenizer
+{
+  typedef typename DependentSubstringType::char_type CharType;
+  typedef typename DependentSubstringType::substring_type SubstringType;
+
+public:
+  explicit nsTWhitespaceTokenizer(const SubstringType& aSource)
+    : mIter(aSource.Data(), aSource.Length())
+    , mEnd(aSource.Data() + aSource.Length(), aSource.Data(),
+           aSource.Length())
+    , mWhitespaceBeforeFirstToken(false)
+    , mWhitespaceAfterCurrentToken(false)
+  {
+    while (mIter < mEnd && IsWhitespace(*mIter)) {
+      mWhitespaceBeforeFirstToken = true;
+      ++mIter;
+    }
+  }
+
+  /**
+   * Checks if any more tokens are available.
+   */
+  bool hasMoreTokens() const
+  {
+    return mIter < mEnd;
+  }
+
+  /*
+   * Returns true if there is whitespace prior to the first token.
+   */
+  bool whitespaceBeforeFirstToken() const
+  {
+    return mWhitespaceBeforeFirstToken;
+  }
+
+  /*
+   * Returns true if there is any whitespace after the current token.
+   * This is always true unless we're reading the last token.
+   */
+  bool whitespaceAfterCurrentToken() const
+  {
+    return mWhitespaceAfterCurrentToken;
+  }
+
+  /**
+   * Returns the next token.
+   */
+  const DependentSubstringType nextToken()
+  {
+    const mozilla::RangedPtr<const CharType> tokenStart = mIter;
+    while (mIter < mEnd && !IsWhitespace(*mIter)) {
+      ++mIter;
+    }
+    const mozilla::RangedPtr<const CharType> tokenEnd = mIter;
+    mWhitespaceAfterCurrentToken = false;
+    while (mIter < mEnd && IsWhitespace(*mIter)) {
+      mWhitespaceAfterCurrentToken = true;
+      ++mIter;
+    }
+    return Substring(tokenStart.get(), tokenEnd.get());
+  }
+
+private:
+  mozilla::RangedPtr<const CharType> mIter;
+  const mozilla::RangedPtr<const CharType> mEnd;
+  bool mWhitespaceBeforeFirstToken;
+  bool mWhitespaceAfterCurrentToken;
+};
+
+template<bool IsWhitespace(char16_t) = NS_IsAsciiWhitespace>
+class nsWhitespaceTokenizerTemplate
+  : public nsTWhitespaceTokenizer<nsDependentSubstring, IsWhitespace>
+{
+public:
+  explicit nsWhitespaceTokenizerTemplate(const nsSubstring& aSource)
+    : nsTWhitespaceTokenizer<nsDependentSubstring, IsWhitespace>(aSource)
+  {
+  }
+};
+
+typedef nsWhitespaceTokenizerTemplate<> nsWhitespaceTokenizer;
+
+template<bool IsWhitespace(char16_t) = NS_IsAsciiWhitespace>
+class nsCWhitespaceTokenizerTemplate
+  : public nsTWhitespaceTokenizer<nsDependentCSubstring, IsWhitespace>
+{
+public:
+  explicit nsCWhitespaceTokenizerTemplate(const nsCSubstring& aSource)
+    : nsTWhitespaceTokenizer<nsDependentCSubstring, IsWhitespace>(aSource)
+  {
+  }
+};
+
+typedef nsCWhitespaceTokenizerTemplate<> nsCWhitespaceTokenizer;
+
+#endif /* __nsWhitespaceTokenizer_h */
diff --git a/xpcom/ds/nsWindowsRegKey.cpp b/xpcom/ds/nsWindowsRegKey.cpp
new file mode 100644
index 000000000..55571d8f9
--- /dev/null
+++ b/xpcom/ds/nsWindowsRegKey.cpp
@@ -0,0 +1,579 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <windows.h>
+#include <shlwapi.h>
+#include <stdlib.h>
+#include "nsWindowsRegKey.h"
+#include "nsString.h"
+#include "nsCOMPtr.h"
+#include "mozilla/Attributes.h"
+#include "nsAutoPtr.h"
+
+//-----------------------------------------------------------------------------
+
+// According to MSDN, the following limits apply (in characters excluding room
+// for terminating null character):
+#define MAX_KEY_NAME_LEN     255
+#define MAX_VALUE_NAME_LEN   16383
+
+class nsWindowsRegKey final : public nsIWindowsRegKey
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIWINDOWSREGKEY
+
+  nsWindowsRegKey()
+    : mKey(nullptr)
+    , mWatchEvent(nullptr)
+    , mWatchRecursive(FALSE)
+  {
+  }
+
+private:
+  ~nsWindowsRegKey()
+  {
+    Close();
+  }
+
+  HKEY   mKey;
+  HANDLE mWatchEvent;
+  BOOL   mWatchRecursive;
+};
+
+NS_IMPL_ISUPPORTS(nsWindowsRegKey, nsIWindowsRegKey)
+
+NS_IMETHODIMP
+nsWindowsRegKey::GetKey(HKEY* aKey)
+{
+  *aKey = mKey;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::SetKey(HKEY aKey)
+{
+  // We do not close the older aKey!
+  StopWatching();
+
+  mKey = aKey;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::Close()
+{
+  StopWatching();
+
+  if (mKey) {
+    RegCloseKey(mKey);
+    mKey = nullptr;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::Open(uint32_t aRootKey, const nsAString& aPath,
+                      uint32_t aMode)
+{
+  Close();
+
+  LONG rv = RegOpenKeyExW((HKEY)(intptr_t)aRootKey,
+                          PromiseFlatString(aPath).get(), 0, (REGSAM)aMode,
+                          &mKey);
+  return (rv == ERROR_SUCCESS) ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::Create(uint32_t aRootKey, const nsAString& aPath,
+                        uint32_t aMode)
+{
+  Close();
+
+  DWORD disposition;
+  LONG rv = RegCreateKeyExW((HKEY)(intptr_t)aRootKey,
+                            PromiseFlatString(aPath).get(), 0, nullptr,
+                            REG_OPTION_NON_VOLATILE, (REGSAM)aMode, nullptr,
+                            &mKey, &disposition);
+  return (rv == ERROR_SUCCESS) ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::OpenChild(const nsAString& aPath, uint32_t aMode,
+                           nsIWindowsRegKey** aResult)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  nsCOMPtr<nsIWindowsRegKey> child = new nsWindowsRegKey();
+
+  nsresult rv = child->Open((uintptr_t)mKey, aPath, aMode);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  child.swap(*aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::CreateChild(const nsAString& aPath, uint32_t aMode,
+                             nsIWindowsRegKey** aResult)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  nsCOMPtr<nsIWindowsRegKey> child = new nsWindowsRegKey();
+
+  nsresult rv = child->Create((uintptr_t)mKey, aPath, aMode);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  child.swap(*aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::GetChildCount(uint32_t* aResult)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  DWORD numSubKeys;
+  LONG rv = RegQueryInfoKeyW(mKey, nullptr, nullptr, nullptr, &numSubKeys,
+                             nullptr, nullptr, nullptr, nullptr, nullptr,
+                             nullptr, nullptr);
+  if (rv != ERROR_SUCCESS) {
+    return NS_ERROR_FAILURE;
+  }
+
+  *aResult = numSubKeys;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::GetChildName(uint32_t aIndex, nsAString& aResult)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  FILETIME lastWritten;
+
+  wchar_t nameBuf[MAX_KEY_NAME_LEN + 1];
+  DWORD nameLen = sizeof(nameBuf) / sizeof(nameBuf[0]);
+
+  LONG rv = RegEnumKeyExW(mKey, aIndex, nameBuf, &nameLen, nullptr, nullptr,
+                          nullptr, &lastWritten);
+  if (rv != ERROR_SUCCESS) {
+    return NS_ERROR_NOT_AVAILABLE;  // XXX what's the best error code here?
+  }
+
+  aResult.Assign(nameBuf, nameLen);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::HasChild(const nsAString& aName, bool* aResult)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  // Check for the existence of a child key by opening the key with minimal
+  // rights.  Perhaps there is a more efficient way to do this?
+
+  HKEY key;
+  LONG rv = RegOpenKeyExW(mKey, PromiseFlatString(aName).get(), 0,
+                          STANDARD_RIGHTS_READ, &key);
+
+  if ((*aResult = (rv == ERROR_SUCCESS && key))) {
+    RegCloseKey(key);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::GetValueCount(uint32_t* aResult)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  DWORD numValues;
+  LONG rv = RegQueryInfoKeyW(mKey, nullptr, nullptr, nullptr, nullptr,
+                             nullptr, nullptr, &numValues, nullptr, nullptr,
+                             nullptr, nullptr);
+  if (rv != ERROR_SUCCESS) {
+    return NS_ERROR_FAILURE;
+  }
+
+  *aResult = numValues;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::GetValueName(uint32_t aIndex, nsAString& aResult)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  wchar_t nameBuf[MAX_VALUE_NAME_LEN];
+  DWORD nameLen = sizeof(nameBuf) / sizeof(nameBuf[0]);
+
+  LONG rv = RegEnumValueW(mKey, aIndex, nameBuf, &nameLen, nullptr, nullptr,
+                          nullptr, nullptr);
+  if (rv != ERROR_SUCCESS) {
+    return NS_ERROR_NOT_AVAILABLE;  // XXX what's the best error code here?
+  }
+
+  aResult.Assign(nameBuf, nameLen);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::HasValue(const nsAString& aName, bool* aResult)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  LONG rv = RegQueryValueExW(mKey, PromiseFlatString(aName).get(), 0, nullptr,
+                             nullptr, nullptr);
+
+  *aResult = (rv == ERROR_SUCCESS);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::RemoveChild(const nsAString& aName)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  LONG rv = RegDeleteKeyW(mKey, PromiseFlatString(aName).get());
+
+  return (rv == ERROR_SUCCESS) ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::RemoveValue(const nsAString& aName)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  LONG rv = RegDeleteValueW(mKey, PromiseFlatString(aName).get());
+
+  return (rv == ERROR_SUCCESS) ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::GetValueType(const nsAString& aName, uint32_t* aResult)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  LONG rv = RegQueryValueExW(mKey, PromiseFlatString(aName).get(), 0,
+                             (LPDWORD)aResult, nullptr, nullptr);
+  return (rv == ERROR_SUCCESS) ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::ReadStringValue(const nsAString& aName, nsAString& aResult)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  DWORD type, size;
+
+  const nsString& flatName = PromiseFlatString(aName);
+
+  LONG rv = RegQueryValueExW(mKey, flatName.get(), 0, &type, nullptr, &size);
+  if (rv != ERROR_SUCCESS) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // This must be a string type in order to fetch the value as a string.
+  // We're being a bit forgiving here by allowing types other than REG_SZ.
+  if (type != REG_SZ && type != REG_EXPAND_SZ && type != REG_MULTI_SZ) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // The buffer size must be a multiple of 2.
+  if (size % 2 != 0) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (size == 0) {
+    aResult.Truncate();
+    return NS_OK;
+  }
+
+  // |size| may or may not include the terminating null character.
+  DWORD resultLen = size / 2;
+
+  if (!aResult.SetLength(resultLen, mozilla::fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  nsAString::iterator begin;
+  aResult.BeginWriting(begin);
+
+  rv = RegQueryValueExW(mKey, flatName.get(), 0, &type, (LPBYTE)begin.get(),
+                        &size);
+
+  if (!aResult.CharAt(resultLen - 1)) {
+    // The string passed to us had a null terminator in the final position.
+    aResult.Truncate(resultLen - 1);
+  }
+
+  // Expand the environment variables if needed
+  if (type == REG_EXPAND_SZ) {
+    const nsString& flatSource = PromiseFlatString(aResult);
+    resultLen = ExpandEnvironmentStringsW(flatSource.get(), nullptr, 0);
+    if (resultLen > 1) {
+      nsAutoString expandedResult;
+      // |resultLen| includes the terminating null character
+      --resultLen;
+      if (!expandedResult.SetLength(resultLen, mozilla::fallible)) {
+        return NS_ERROR_OUT_OF_MEMORY;
+      }
+
+      nsAString::iterator begin;
+      expandedResult.BeginWriting(begin);
+
+      resultLen = ExpandEnvironmentStringsW(flatSource.get(),
+                                            wwc(begin.get()),
+                                            resultLen + 1);
+      if (resultLen <= 0) {
+        rv = ERROR_UNKNOWN_FEATURE;
+        aResult.Truncate();
+      } else {
+        rv = ERROR_SUCCESS;
+        aResult = expandedResult;
+      }
+    } else if (resultLen == 1) {
+      // It apparently expands to nothing (just a null terminator).
+      aResult.Truncate();
+    }
+  }
+
+  return (rv == ERROR_SUCCESS) ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::ReadIntValue(const nsAString& aName, uint32_t* aResult)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  DWORD size = sizeof(*aResult);
+  LONG rv = RegQueryValueExW(mKey, PromiseFlatString(aName).get(), 0, nullptr,
+                             (LPBYTE)aResult, &size);
+  return (rv == ERROR_SUCCESS) ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::ReadInt64Value(const nsAString& aName, uint64_t* aResult)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  DWORD size = sizeof(*aResult);
+  LONG rv = RegQueryValueExW(mKey, PromiseFlatString(aName).get(), 0, nullptr,
+                             (LPBYTE)aResult, &size);
+  return (rv == ERROR_SUCCESS) ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::ReadBinaryValue(const nsAString& aName, nsACString& aResult)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  DWORD size;
+  LONG rv = RegQueryValueExW(mKey, PromiseFlatString(aName).get(), 0,
+                             nullptr, nullptr, &size);
+
+  if (rv != ERROR_SUCCESS) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (!size) {
+    aResult.Truncate();
+    return NS_OK;
+  }
+
+  if (!aResult.SetLength(size, mozilla::fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  nsACString::iterator begin;
+  aResult.BeginWriting(begin);
+
+  rv = RegQueryValueExW(mKey, PromiseFlatString(aName).get(), 0, nullptr,
+                        (LPBYTE)begin.get(), &size);
+  return (rv == ERROR_SUCCESS) ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::WriteStringValue(const nsAString& aName,
+                                  const nsAString& aValue)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  // Need to indicate complete size of buffer including null terminator.
+  const nsString& flatValue = PromiseFlatString(aValue);
+
+  LONG rv = RegSetValueExW(mKey, PromiseFlatString(aName).get(), 0, REG_SZ,
+                           (const BYTE*)flatValue.get(),
+                           (flatValue.Length() + 1) * sizeof(char16_t));
+  return (rv == ERROR_SUCCESS) ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::WriteIntValue(const nsAString& aName, uint32_t aValue)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  LONG rv = RegSetValueExW(mKey, PromiseFlatString(aName).get(), 0, REG_DWORD,
+                           (const BYTE*)&aValue, sizeof(aValue));
+  return (rv == ERROR_SUCCESS) ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::WriteInt64Value(const nsAString& aName, uint64_t aValue)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  LONG rv = RegSetValueExW(mKey, PromiseFlatString(aName).get(), 0, REG_QWORD,
+                           (const BYTE*)&aValue, sizeof(aValue));
+  return (rv == ERROR_SUCCESS) ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::WriteBinaryValue(const nsAString& aName,
+                                  const nsACString& aValue)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  const nsCString& flatValue = PromiseFlatCString(aValue);
+  LONG rv = RegSetValueExW(mKey, PromiseFlatString(aName).get(), 0, REG_BINARY,
+                           (const BYTE*)flatValue.get(), flatValue.Length());
+  return (rv == ERROR_SUCCESS) ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::StartWatching(bool aRecurse)
+{
+  if (NS_WARN_IF(!mKey)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  if (mWatchEvent) {
+    return NS_OK;
+  }
+
+  mWatchEvent = CreateEvent(nullptr, TRUE, FALSE, nullptr);
+  if (!mWatchEvent) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  DWORD filter = REG_NOTIFY_CHANGE_NAME |
+                 REG_NOTIFY_CHANGE_ATTRIBUTES |
+                 REG_NOTIFY_CHANGE_LAST_SET |
+                 REG_NOTIFY_CHANGE_SECURITY;
+
+  LONG rv = RegNotifyChangeKeyValue(mKey, aRecurse, filter, mWatchEvent, TRUE);
+  if (rv != ERROR_SUCCESS) {
+    StopWatching();
+    // On older versions of Windows, this call is not implemented, so simply
+    // return NS_OK in those cases and pretend that the watching is happening.
+    return (rv == ERROR_CALL_NOT_IMPLEMENTED) ? NS_OK : NS_ERROR_FAILURE;
+  }
+
+  mWatchRecursive = aRecurse;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::StopWatching()
+{
+  if (mWatchEvent) {
+    CloseHandle(mWatchEvent);
+    mWatchEvent = nullptr;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::HasChanged(bool* aResult)
+{
+  if (mWatchEvent && WaitForSingleObject(mWatchEvent, 0) == WAIT_OBJECT_0) {
+    // An event only gets signaled once, then it's done, so we have to set up
+    // another event to watch.
+    StopWatching();
+    StartWatching(mWatchRecursive);
+    *aResult = true;
+  } else {
+    *aResult = false;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWindowsRegKey::IsWatching(bool* aResult)
+{
+  *aResult = (mWatchEvent != nullptr);
+  return NS_OK;
+}
+
+//-----------------------------------------------------------------------------
+
+void
+NS_NewWindowsRegKey(nsIWindowsRegKey** aResult)
+{
+  RefPtr<nsWindowsRegKey> key = new nsWindowsRegKey();
+  key.forget(aResult);
+}
+
+//-----------------------------------------------------------------------------
+
+nsresult
+nsWindowsRegKeyConstructor(nsISupports* aDelegate, const nsIID& aIID,
+                           void** aResult)
+{
+  if (aDelegate) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+
+  nsCOMPtr<nsIWindowsRegKey> key;
+  NS_NewWindowsRegKey(getter_AddRefs(key));
+  return key->QueryInterface(aIID, aResult);
+}
diff --git a/xpcom/ds/nsWindowsRegKey.h b/xpcom/ds/nsWindowsRegKey.h
new file mode 100644
index 000000000..d7930579a
--- /dev/null
+++ b/xpcom/ds/nsWindowsRegKey.h
@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsWindowsRegKey_h__
+#define nsWindowsRegKey_h__
+
+//-----------------------------------------------------------------------------
+
+#include "nsIWindowsRegKey.h"
+
+/**
+ * This ContractID may be used to instantiate a windows registry key object
+ * via the XPCOM component manager.
+ */
+#define NS_WINDOWSREGKEY_CONTRACTID "@mozilla.org/windows-registry-key;1"
+
+/**
+ * This function may be used to instantiate a windows registry key object prior
+ * to XPCOM being initialized.
+ */
+extern "C" void NS_NewWindowsRegKey(nsIWindowsRegKey** aResult);
+
+//-----------------------------------------------------------------------------
+
+#ifdef IMPL_LIBXUL
+
+// a53bc624-d577-4839-b8ec-bb5040a52ff4
+#define NS_WINDOWSREGKEY_CID \
+  { 0xa53bc624, 0xd577, 0x4839, \
+    { 0xb8, 0xec, 0xbb, 0x50, 0x40, 0xa5, 0x2f, 0xf4 } }
+
+extern MOZ_MUST_USE nsresult nsWindowsRegKeyConstructor(nsISupports* aOuter,
+                                                        const nsIID& aIID,
+                                                        void** aResult);
+
+#endif  // IMPL_LIBXUL
+
+//-----------------------------------------------------------------------------
+
+#endif  // nsWindowsRegKey_h__
diff --git a/xpcom/glue/AppData.cpp b/xpcom/glue/AppData.cpp
new file mode 100644
index 000000000..845267e60
--- /dev/null
+++ b/xpcom/glue/AppData.cpp
@@ -0,0 +1,95 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/AppData.h"
+#include "nsXULAppAPI.h"
+#include "nsINIParser.h"
+#include "nsIFile.h"
+#include "nsCRTGlue.h"
+#include "nsAutoPtr.h"
+
+namespace mozilla {
+
+void
+SetAllocatedString(const char*& aStr, const char* aNewValue)
+{
+  NS_Free(const_cast<char*>(aStr));
+  if (aNewValue) {
+    aStr = NS_strdup(aNewValue);
+  } else {
+    aStr = nullptr;
+  }
+}
+
+void
+SetAllocatedString(const char*& aStr, const nsACString& aNewValue)
+{
+  NS_Free(const_cast<char*>(aStr));
+  if (aNewValue.IsEmpty()) {
+    aStr = nullptr;
+  } else {
+    aStr = ToNewCString(aNewValue);
+  }
+}
+
+ScopedAppData::ScopedAppData(const nsXREAppData* aAppData)
+{
+  Zero();
+
+  this->size = aAppData->size;
+
+  SetAllocatedString(this->vendor, aAppData->vendor);
+  SetAllocatedString(this->name, aAppData->name);
+  SetAllocatedString(this->remotingName, aAppData->remotingName);
+  SetAllocatedString(this->version, aAppData->version);
+  SetAllocatedString(this->buildID, aAppData->buildID);
+  SetAllocatedString(this->ID, aAppData->ID);
+  SetAllocatedString(this->copyright, aAppData->copyright);
+  SetAllocatedString(this->profile, aAppData->profile);
+  SetStrongPtr(this->directory, aAppData->directory);
+  this->flags = aAppData->flags;
+
+  if (aAppData->size > offsetof(nsXREAppData, xreDirectory)) {
+    SetStrongPtr(this->xreDirectory, aAppData->xreDirectory);
+    SetAllocatedString(this->minVersion, aAppData->minVersion);
+    SetAllocatedString(this->maxVersion, aAppData->maxVersion);
+  }
+
+  if (aAppData->size > offsetof(nsXREAppData, crashReporterURL)) {
+    SetAllocatedString(this->crashReporterURL, aAppData->crashReporterURL);
+  }
+
+  if (aAppData->size > offsetof(nsXREAppData, UAName)) {
+    SetAllocatedString(this->UAName, aAppData->UAName);
+  }
+
+#if defined(XP_WIN) && defined(MOZ_SANDBOX)
+  sandboxBrokerServices = aAppData->sandboxBrokerServices;
+#endif
+}
+
+ScopedAppData::~ScopedAppData()
+{
+  SetAllocatedString(this->vendor, nullptr);
+  SetAllocatedString(this->name, nullptr);
+  SetAllocatedString(this->remotingName, nullptr);
+  SetAllocatedString(this->version, nullptr);
+  SetAllocatedString(this->buildID, nullptr);
+  SetAllocatedString(this->ID, nullptr);
+  SetAllocatedString(this->copyright, nullptr);
+  SetAllocatedString(this->profile, nullptr);
+
+  NS_IF_RELEASE(this->directory);
+
+  SetStrongPtr(this->xreDirectory, (nsIFile*)nullptr);
+  SetAllocatedString(this->minVersion, nullptr);
+  SetAllocatedString(this->maxVersion, nullptr);
+
+  SetAllocatedString(this->crashReporterURL, nullptr);
+  SetAllocatedString(this->UAName, nullptr);
+}
+
+} // namespace mozilla
diff --git a/xpcom/glue/AppData.h b/xpcom/glue/AppData.h
new file mode 100644
index 000000000..0134df32c
--- /dev/null
+++ b/xpcom/glue/AppData.h
@@ -0,0 +1,63 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_AppData_h
+#define mozilla_AppData_h
+
+#include "nsXREAppData.h"
+#include "nscore.h"
+#include "nsStringGlue.h"
+#include "nsISupportsUtils.h"
+
+namespace mozilla {
+
+// Like nsXREAppData, but releases all strong refs/allocated memory
+// in the destructor.
+class ScopedAppData : public nsXREAppData
+{
+public:
+  ScopedAppData()
+  {
+    Zero();
+    this->size = sizeof(*this);
+  }
+
+  explicit ScopedAppData(const nsXREAppData* aAppData);
+
+  void Zero() { memset(this, 0, sizeof(*this)); }
+
+  ~ScopedAppData();
+};
+
+/**
+ * Given |aStr| is holding a string allocated with NS_Alloc, or null:
+ * replace the value in |aStr| with a new value.
+ *
+ * @param aNewValue Null is permitted. The string is cloned with NS_strdup.
+ */
+void SetAllocatedString(const char*& aStr, const char* aNewValue);
+
+/**
+ * Given "str" is holding a string allocated with NS_Alloc, or null:
+ * replace the value in "str" with a new value.
+ *
+ * @param aNewValue If |aNewValue| is the empty string, |aStr| will be set
+ *                  to null.
+ */
+void SetAllocatedString(const char*& aStr, const nsACString& aNewValue);
+
+template<class T>
+void
+SetStrongPtr(T*& aPtr, T* aNewValue)
+{
+  NS_IF_RELEASE(aPtr);
+  aPtr = aNewValue;
+  NS_IF_ADDREF(aPtr);
+}
+
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/glue/AutoRestore.h b/xpcom/glue/AutoRestore.h
new file mode 100644
index 000000000..20909c92c
--- /dev/null
+++ b/xpcom/glue/AutoRestore.h
@@ -0,0 +1,55 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* functions for restoring saved values at the end of a C++ scope */
+
+#ifndef mozilla_AutoRestore_h_
+#define mozilla_AutoRestore_h_
+
+#include "mozilla/Attributes.h" // MOZ_STACK_CLASS
+#include "mozilla/GuardObjects.h"
+
+namespace mozilla {
+
+/**
+ * Save the current value of a variable and restore it when the object
+ * goes out of scope.  For example:
+ *   {
+ *     AutoRestore<bool> savePainting(mIsPainting);
+ *     mIsPainting = true;
+ *
+ *     // ... your code here ...
+ *
+ *     // mIsPainting is reset to its old value at the end of this block
+ *   }
+ */
+template<class T>
+class MOZ_RAII AutoRestore
+{
+private:
+  T& mLocation;
+  T mValue;
+  MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
+public:
+  explicit AutoRestore(T& aValue MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
+    : mLocation(aValue)
+    , mValue(aValue)
+  {
+    MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+  }
+  ~AutoRestore()
+  {
+    mLocation = mValue;
+  }
+  T SavedValue() const
+  {
+    return mValue;
+  }
+};
+
+} // namespace mozilla
+
+#endif /* !defined(mozilla_AutoRestore_h_) */
diff --git a/xpcom/glue/BlockingResourceBase.cpp b/xpcom/glue/BlockingResourceBase.cpp
new file mode 100644
index 000000000..ada02c72c
--- /dev/null
+++ b/xpcom/glue/BlockingResourceBase.cpp
@@ -0,0 +1,511 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/BlockingResourceBase.h"
+
+#ifdef DEBUG
+#include "prthread.h"
+
+#include "nsAutoPtr.h"
+
+#ifndef MOZ_CALLSTACK_DISABLED
+#include "CodeAddressService.h"
+#include "nsHashKeys.h"
+#include "mozilla/StackWalk.h"
+#include "nsTHashtable.h"
+#endif
+
+#include "mozilla/CondVar.h"
+#include "mozilla/DeadlockDetector.h"
+#include "mozilla/ReentrantMonitor.h"
+#include "mozilla/Mutex.h"
+
+#if defined(MOZILLA_INTERNAL_API)
+#include "GeckoProfiler.h"
+#endif //MOZILLA_INTERNAL_API
+
+#endif // ifdef DEBUG
+
+namespace mozilla {
+//
+// BlockingResourceBase implementation
+//
+
+// static members
+const char* const BlockingResourceBase::kResourceTypeName[] = {
+  // needs to be kept in sync with BlockingResourceType
+  "Mutex", "ReentrantMonitor", "CondVar"
+};
+
+#ifdef DEBUG
+
+PRCallOnceType BlockingResourceBase::sCallOnce;
+unsigned BlockingResourceBase::sResourceAcqnChainFrontTPI = (unsigned)-1;
+BlockingResourceBase::DDT* BlockingResourceBase::sDeadlockDetector;
+
+
+void
+BlockingResourceBase::StackWalkCallback(uint32_t aFrameNumber, void* aPc,
+                                        void* aSp, void* aClosure)
+{
+#ifndef MOZ_CALLSTACK_DISABLED
+  AcquisitionState* state = (AcquisitionState*)aClosure;
+  state->AppendElement(aPc);
+#endif
+}
+
+void
+BlockingResourceBase::GetStackTrace(AcquisitionState& aState)
+{
+#ifndef MOZ_CALLSTACK_DISABLED
+  // Skip this function and the calling function.
+  const uint32_t kSkipFrames = 2;
+
+  aState.Clear();
+
+  // NB: Ignore the return value, there's nothing useful we can do if this
+  //     this fails.
+  MozStackWalk(StackWalkCallback, kSkipFrames, 24, &aState, 0, nullptr);
+#endif
+}
+
+/**
+ * PrintCycle
+ * Append to |aOut| detailed information about the circular
+ * dependency in |aCycle|.  Returns true if it *appears* that this
+ * cycle may represent an imminent deadlock, but this is merely a
+ * heuristic; the value returned may be a false positive or false
+ * negative.
+ *
+ * *NOT* thread safe.  Calls |Print()|.
+ *
+ * FIXME bug 456272 hack alert: because we can't write call
+ * contexts into strings, all info is written to stderr, but only
+ * some info is written into |aOut|
+ */
+bool
+PrintCycle(const BlockingResourceBase::DDT::ResourceAcquisitionArray* aCycle,
+           nsACString& aOut)
+{
+  NS_ASSERTION(aCycle->Length() > 1, "need > 1 element for cycle!");
+
+  bool maybeImminent = true;
+
+  fputs("=== Cyclical dependency starts at\n", stderr);
+  aOut += "Cyclical dependency starts at\n";
+
+  const BlockingResourceBase::DDT::ResourceAcquisitionArray::elem_type res =
+    aCycle->ElementAt(0);
+  maybeImminent &= res->Print(aOut);
+
+  BlockingResourceBase::DDT::ResourceAcquisitionArray::index_type i;
+  BlockingResourceBase::DDT::ResourceAcquisitionArray::size_type len =
+    aCycle->Length();
+  const BlockingResourceBase::DDT::ResourceAcquisitionArray::elem_type* it =
+    1 + aCycle->Elements();
+  for (i = 1; i < len - 1; ++i, ++it) {
+    fputs("\n--- Next dependency:\n", stderr);
+    aOut += "\nNext dependency:\n";
+
+    maybeImminent &= (*it)->Print(aOut);
+  }
+
+  fputs("\n=== Cycle completed at\n", stderr);
+  aOut += "Cycle completed at\n";
+  (*it)->Print(aOut);
+
+  return maybeImminent;
+}
+
+#ifndef MOZ_CALLSTACK_DISABLED
+struct CodeAddressServiceLock final
+{
+  static void Unlock() { }
+  static void Lock() { }
+  static bool IsLocked() { return true; }
+};
+
+struct CodeAddressServiceStringAlloc final
+{
+  static char* copy(const char* aString) { return ::strdup(aString); }
+  static void free(char* aString) { ::free(aString); }
+};
+
+class CodeAddressServiceStringTable final
+{
+public:
+  CodeAddressServiceStringTable() : mSet(32) {}
+
+  const char* Intern(const char* aString)
+  {
+    nsCharPtrHashKey* e = mSet.PutEntry(aString);
+    return e->GetKey();
+  }
+
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return mSet.SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+private:
+  typedef nsTHashtable<nsCharPtrHashKey> StringSet;
+  StringSet mSet;
+};
+
+typedef CodeAddressService<CodeAddressServiceStringTable,
+                           CodeAddressServiceStringAlloc,
+                           CodeAddressServiceLock> WalkTheStackCodeAddressService;
+#endif
+
+bool
+BlockingResourceBase::Print(nsACString& aOut) const
+{
+  fprintf(stderr, "--- %s : %s",
+          kResourceTypeName[mType], mName);
+  aOut += BlockingResourceBase::kResourceTypeName[mType];
+  aOut += " : ";
+  aOut += mName;
+
+  bool acquired = IsAcquired();
+
+  if (acquired) {
+    fputs(" (currently acquired)\n", stderr);
+    aOut += " (currently acquired)\n";
+  }
+
+  fputs(" calling context\n", stderr);
+#ifdef MOZ_CALLSTACK_DISABLED
+  fputs("  [stack trace unavailable]\n", stderr);
+#else
+  const AcquisitionState& state = acquired ? mAcquired : mFirstSeen;
+
+  WalkTheStackCodeAddressService addressService;
+
+  for (uint32_t i = 0; i < state.Length(); i++) {
+    const size_t kMaxLength = 1024;
+    char buffer[kMaxLength];
+    addressService.GetLocation(i + 1, state[i], buffer, kMaxLength);
+    const char* fmt = "    %s\n";
+    aOut.AppendLiteral("    ");
+    aOut.Append(buffer);
+    aOut.AppendLiteral("\n");
+    fprintf(stderr, fmt, buffer);
+  }
+
+#endif
+
+  return acquired;
+}
+
+
+BlockingResourceBase::BlockingResourceBase(
+    const char* aName,
+    BlockingResourceBase::BlockingResourceType aType)
+  : mName(aName)
+  , mType(aType)
+#ifdef MOZ_CALLSTACK_DISABLED
+  , mAcquired(false)
+#else
+  , mAcquired()
+#endif
+{
+  MOZ_ASSERT(mName, "Name must be nonnull");
+  // PR_CallOnce guaranatees that InitStatics is called in a
+  // thread-safe way
+  if (PR_SUCCESS != PR_CallOnce(&sCallOnce, InitStatics)) {
+    NS_RUNTIMEABORT("can't initialize blocking resource static members");
+  }
+
+  mChainPrev = 0;
+  sDeadlockDetector->Add(this);
+}
+
+
+BlockingResourceBase::~BlockingResourceBase()
+{
+  // we don't check for really obviously bad things like freeing
+  // Mutexes while they're still locked.  it is assumed that the
+  // base class, or its underlying primitive, will check for such
+  // stupid mistakes.
+  mChainPrev = 0;             // racy only for stupidly buggy client code
+  if (sDeadlockDetector) {
+    sDeadlockDetector->Remove(this);
+  }
+}
+
+
+size_t
+BlockingResourceBase::SizeOfDeadlockDetector(MallocSizeOf aMallocSizeOf)
+{
+  return sDeadlockDetector ?
+      sDeadlockDetector->SizeOfIncludingThis(aMallocSizeOf) : 0;
+}
+
+
+PRStatus
+BlockingResourceBase::InitStatics()
+{
+  PR_NewThreadPrivateIndex(&sResourceAcqnChainFrontTPI, 0);
+  sDeadlockDetector = new DDT();
+  if (!sDeadlockDetector) {
+    NS_RUNTIMEABORT("can't allocate deadlock detector");
+  }
+  return PR_SUCCESS;
+}
+
+
+void
+BlockingResourceBase::Shutdown()
+{
+  delete sDeadlockDetector;
+  sDeadlockDetector = 0;
+}
+
+
+void
+BlockingResourceBase::CheckAcquire()
+{
+  if (mType == eCondVar) {
+    NS_NOTYETIMPLEMENTED(
+      "FIXME bug 456272: annots. to allow CheckAcquire()ing condvars");
+    return;
+  }
+
+  BlockingResourceBase* chainFront = ResourceChainFront();
+  nsAutoPtr<DDT::ResourceAcquisitionArray> cycle(
+    sDeadlockDetector->CheckAcquisition(
+      chainFront ? chainFront : 0, this));
+  if (!cycle) {
+    return;
+  }
+
+#ifndef MOZ_CALLSTACK_DISABLED
+  // Update the current stack before printing.
+  GetStackTrace(mAcquired);
+#endif
+
+  fputs("###!!! ERROR: Potential deadlock detected:\n", stderr);
+  nsAutoCString out("Potential deadlock detected:\n");
+  bool maybeImminent = PrintCycle(cycle, out);
+
+  if (maybeImminent) {
+    fputs("\n###!!! Deadlock may happen NOW!\n\n", stderr);
+    out.AppendLiteral("\n###!!! Deadlock may happen NOW!\n\n");
+  } else {
+    fputs("\nDeadlock may happen for some other execution\n\n",
+          stderr);
+    out.AppendLiteral("\nDeadlock may happen for some other execution\n\n");
+  }
+
+  // XXX can customize behavior on whether we /think/ deadlock is
+  // XXX about to happen.  for example:
+  // XXX   if (maybeImminent)
+  //           NS_RUNTIMEABORT(out.get());
+  NS_ERROR(out.get());
+}
+
+
+void
+BlockingResourceBase::Acquire()
+{
+  if (mType == eCondVar) {
+    NS_NOTYETIMPLEMENTED(
+      "FIXME bug 456272: annots. to allow Acquire()ing condvars");
+    return;
+  }
+  NS_ASSERTION(!IsAcquired(),
+               "reacquiring already acquired resource");
+
+  ResourceChainAppend(ResourceChainFront());
+
+#ifdef MOZ_CALLSTACK_DISABLED
+  mAcquired = true;
+#else
+  // Take a stack snapshot.
+  GetStackTrace(mAcquired);
+  if (mFirstSeen.IsEmpty()) {
+    mFirstSeen = mAcquired;
+  }
+#endif
+}
+
+
+void
+BlockingResourceBase::Release()
+{
+  if (mType == eCondVar) {
+    NS_NOTYETIMPLEMENTED(
+      "FIXME bug 456272: annots. to allow Release()ing condvars");
+    return;
+  }
+
+  BlockingResourceBase* chainFront = ResourceChainFront();
+  NS_ASSERTION(chainFront && IsAcquired(),
+               "Release()ing something that hasn't been Acquire()ed");
+
+  if (chainFront == this) {
+    ResourceChainRemove();
+  } else {
+    // not an error, but makes code hard to reason about.
+    NS_WARNING("Resource acquired is being released in non-LIFO order; why?\n");
+    nsCString tmp;
+    Print(tmp);
+
+    // remove this resource from wherever it lives in the chain
+    // we walk backwards in order of acquisition:
+    //  (1)  ...node<-prev<-curr...
+    //              /     /
+    //  (2)  ...prev<-curr...
+    BlockingResourceBase* curr = chainFront;
+    BlockingResourceBase* prev = nullptr;
+    while (curr && (prev = curr->mChainPrev) && (prev != this)) {
+      curr = prev;
+    }
+    if (prev == this) {
+      curr->mChainPrev = prev->mChainPrev;
+    }
+  }
+
+  ClearAcquisitionState();
+}
+
+
+//
+// Debug implementation of (OffTheBooks)Mutex
+void
+OffTheBooksMutex::Lock()
+{
+  CheckAcquire();
+  PR_Lock(mLock);
+  Acquire();       // protected by mLock
+}
+
+void
+OffTheBooksMutex::Unlock()
+{
+  Release();                  // protected by mLock
+  PRStatus status = PR_Unlock(mLock);
+  NS_ASSERTION(PR_SUCCESS == status, "bad Mutex::Unlock()");
+}
+
+
+//
+// Debug implementation of ReentrantMonitor
+void
+ReentrantMonitor::Enter()
+{
+  BlockingResourceBase* chainFront = ResourceChainFront();
+
+  // the code below implements monitor reentrancy semantics
+
+  if (this == chainFront) {
+    // immediately re-entered the monitor: acceptable
+    PR_EnterMonitor(mReentrantMonitor);
+    ++mEntryCount;
+    return;
+  }
+
+  // this is sort of a hack around not recording the thread that
+  // owns this monitor
+  if (chainFront) {
+    for (BlockingResourceBase* br = ResourceChainPrev(chainFront);
+         br;
+         br = ResourceChainPrev(br)) {
+      if (br == this) {
+        NS_WARNING(
+          "Re-entering ReentrantMonitor after acquiring other resources.");
+
+        // show the caller why this is potentially bad
+        CheckAcquire();
+
+        PR_EnterMonitor(mReentrantMonitor);
+        ++mEntryCount;
+        return;
+      }
+    }
+  }
+
+  CheckAcquire();
+  PR_EnterMonitor(mReentrantMonitor);
+  NS_ASSERTION(mEntryCount == 0, "ReentrantMonitor isn't free!");
+  Acquire();       // protected by mReentrantMonitor
+  mEntryCount = 1;
+}
+
+void
+ReentrantMonitor::Exit()
+{
+  if (--mEntryCount == 0) {
+    Release();              // protected by mReentrantMonitor
+  }
+  PRStatus status = PR_ExitMonitor(mReentrantMonitor);
+  NS_ASSERTION(PR_SUCCESS == status, "bad ReentrantMonitor::Exit()");
+}
+
+nsresult
+ReentrantMonitor::Wait(PRIntervalTime aInterval)
+{
+  AssertCurrentThreadIn();
+
+  // save monitor state and reset it to empty
+  int32_t savedEntryCount = mEntryCount;
+  AcquisitionState savedAcquisitionState = GetAcquisitionState();
+  BlockingResourceBase* savedChainPrev = mChainPrev;
+  mEntryCount = 0;
+  ClearAcquisitionState();
+  mChainPrev = 0;
+
+  nsresult rv;
+#if defined(MOZILLA_INTERNAL_API)
+  {
+    GeckoProfilerSleepRAII profiler_sleep;
+#endif //MOZILLA_INTERNAL_API
+
+    // give up the monitor until we're back from Wait()
+    rv = PR_Wait(mReentrantMonitor, aInterval) == PR_SUCCESS ? NS_OK :
+                                                               NS_ERROR_FAILURE;
+
+#if defined(MOZILLA_INTERNAL_API)
+  }
+#endif //MOZILLA_INTERNAL_API
+
+  // restore saved state
+  mEntryCount = savedEntryCount;
+  SetAcquisitionState(savedAcquisitionState);
+  mChainPrev = savedChainPrev;
+
+  return rv;
+}
+
+
+//
+// Debug implementation of CondVar
+nsresult
+CondVar::Wait(PRIntervalTime aInterval)
+{
+  AssertCurrentThreadOwnsMutex();
+
+  // save mutex state and reset to empty
+  AcquisitionState savedAcquisitionState = mLock->GetAcquisitionState();
+  BlockingResourceBase* savedChainPrev = mLock->mChainPrev;
+  mLock->ClearAcquisitionState();
+  mLock->mChainPrev = 0;
+
+  // give up mutex until we're back from Wait()
+  nsresult rv =
+    PR_WaitCondVar(mCvar, aInterval) == PR_SUCCESS ? NS_OK : NS_ERROR_FAILURE;
+
+  // restore saved state
+  mLock->SetAcquisitionState(savedAcquisitionState);
+  mLock->mChainPrev = savedChainPrev;
+
+  return rv;
+}
+
+#endif // ifdef DEBUG
+
+
+} // namespace mozilla
diff --git a/xpcom/glue/BlockingResourceBase.h b/xpcom/glue/BlockingResourceBase.h
new file mode 100644
index 000000000..d70fbcbbf
--- /dev/null
+++ b/xpcom/glue/BlockingResourceBase.h
@@ -0,0 +1,344 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+#ifndef mozilla_BlockingResourceBase_h
+#define mozilla_BlockingResourceBase_h
+
+#include "mozilla/Logging.h"
+
+#include "nscore.h"
+#include "nsDebug.h"
+#include "nsError.h"
+#include "nsISupportsImpl.h"
+
+#ifdef DEBUG
+
+// NB: Comment this out to enable callstack tracking.
+#define MOZ_CALLSTACK_DISABLED
+
+#include "prinit.h"
+
+#include "nsStringGlue.h"
+
+#ifndef MOZ_CALLSTACK_DISABLED
+#include "nsTArray.h"
+#endif
+
+#include "nsXPCOM.h"
+#endif
+
+//
+// This header is not meant to be included by client code.
+//
+
+namespace mozilla {
+
+#ifdef DEBUG
+template <class T> class DeadlockDetector;
+#endif
+
+/**
+ * BlockingResourceBase
+ * Base class of resources that might block clients trying to acquire them.
+ * Does debugging and deadlock detection in DEBUG builds.
+ **/
+class BlockingResourceBase
+{
+public:
+  // Needs to be kept in sync with kResourceTypeNames.
+  enum BlockingResourceType { eMutex, eReentrantMonitor, eCondVar };
+
+  /**
+   * kResourceTypeName
+   * Human-readable version of BlockingResourceType enum.
+   */
+  static const char* const kResourceTypeName[];
+
+
+#ifdef DEBUG
+
+  static size_t
+  SizeOfDeadlockDetector(MallocSizeOf aMallocSizeOf);
+
+  /**
+   * Print
+   * Write a description of this blocking resource to |aOut|.  If
+   * the resource appears to be currently acquired, the current
+   * acquisition context is printed and true is returned.
+   * Otherwise, we print the context from |aFirstSeen|, the
+   * first acquisition from which the code calling |Print()|
+   * became interested in us, and return false.
+   *
+   * *NOT* thread safe.  Reads |mAcquisitionContext| without
+   * synchronization, but this will not cause correctness
+   * problems.
+   *
+   * FIXME bug 456272: hack alert: because we can't write call
+   * contexts into strings, all info is written to stderr, but
+   * only some info is written into |aOut|
+   */
+  bool Print(nsACString& aOut) const;
+
+  size_t
+  SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
+  {
+    // NB: |mName| is not reported as it's expected to be a static string.
+    //     If we switch to a nsString it should be added to the tally.
+    //     |mChainPrev| is not reported because its memory is not owned.
+    size_t n = aMallocSizeOf(this);
+    return n;
+  }
+
+  // ``DDT'' = ``Deadlock Detector Type''
+  typedef DeadlockDetector<BlockingResourceBase> DDT;
+
+protected:
+#ifdef MOZ_CALLSTACK_DISABLED
+  typedef bool AcquisitionState;
+#else
+  typedef AutoTArray<void*, 24> AcquisitionState;
+#endif
+
+  /**
+   * BlockingResourceBase
+   * Initialize this blocking resource.  Also hooks the resource into
+   * instrumentation code.
+   *
+   * Thread safe.
+   *
+   * @param aName A meaningful, unique name that can be used in
+   *              error messages, et al.
+   * @param aType The specific type of |this|, if any.
+   **/
+  BlockingResourceBase(const char* aName, BlockingResourceType aType);
+
+  ~BlockingResourceBase();
+
+  /**
+   * CheckAcquire
+   *
+   * Thread safe.
+   **/
+  void CheckAcquire();
+
+  /**
+   * Acquire
+   *
+   * *NOT* thread safe.  Requires ownership of underlying resource.
+   **/
+  void Acquire(); //NS_NEEDS_RESOURCE(this)
+
+  /**
+   * Release
+   * Remove this resource from the current thread's acquisition chain.
+   * The resource does not have to be at the front of the chain, although
+   * it is confusing to release resources in a different order than they
+   * are acquired.  This generates a warning.
+   *
+   * *NOT* thread safe.  Requires ownership of underlying resource.
+   **/
+  void Release();             //NS_NEEDS_RESOURCE(this)
+
+  /**
+   * ResourceChainFront
+   *
+   * Thread safe.
+   *
+   * @return the front of the resource acquisition chain, i.e., the last
+   *         resource acquired.
+   */
+  static BlockingResourceBase* ResourceChainFront()
+  {
+    return
+      (BlockingResourceBase*)PR_GetThreadPrivate(sResourceAcqnChainFrontTPI);
+  }
+
+  /**
+   * ResourceChainPrev
+   *
+   * *NOT* thread safe.  Requires ownership of underlying resource.
+   */
+  static BlockingResourceBase* ResourceChainPrev(
+      const BlockingResourceBase* aResource)
+  {
+    return aResource->mChainPrev;
+  } //NS_NEEDS_RESOURCE(this)
+
+  /**
+   * ResourceChainAppend
+   * Set |this| to the front of the resource acquisition chain, and link
+   * |this| to |aPrev|.
+   *
+   * *NOT* thread safe.  Requires ownership of underlying resource.
+   */
+  void ResourceChainAppend(BlockingResourceBase* aPrev)
+  {
+    mChainPrev = aPrev;
+    PR_SetThreadPrivate(sResourceAcqnChainFrontTPI, this);
+  } //NS_NEEDS_RESOURCE(this)
+
+  /**
+   * ResourceChainRemove
+   * Remove |this| from the front of the resource acquisition chain.
+   *
+   * *NOT* thread safe.  Requires ownership of underlying resource.
+   */
+  void ResourceChainRemove()
+  {
+    NS_ASSERTION(this == ResourceChainFront(), "not at chain front");
+    PR_SetThreadPrivate(sResourceAcqnChainFrontTPI, mChainPrev);
+  } //NS_NEEDS_RESOURCE(this)
+
+  /**
+   * GetAcquisitionState
+   * Return whether or not this resource was acquired.
+   *
+   * *NOT* thread safe.  Requires ownership of underlying resource.
+   */
+  AcquisitionState GetAcquisitionState()
+  {
+    return mAcquired;
+  }
+
+  /**
+   * SetAcquisitionState
+   * Set whether or not this resource was acquired.
+   *
+   * *NOT* thread safe.  Requires ownership of underlying resource.
+   */
+  void SetAcquisitionState(const AcquisitionState& aAcquisitionState)
+  {
+    mAcquired = aAcquisitionState;
+  }
+
+  /**
+   * ClearAcquisitionState
+   * Indicate this resource is not acquired.
+   *
+   * *NOT* thread safe.  Requires ownership of underlying resource.
+   */
+  void ClearAcquisitionState()
+  {
+#ifdef MOZ_CALLSTACK_DISABLED
+    mAcquired = false;
+#else
+    mAcquired.Clear();
+#endif
+  }
+
+  /**
+   * IsAcquired
+   * Indicates if this resource is acquired.
+   *
+   * *NOT* thread safe.  Requires ownership of underlying resource.
+   */
+  bool IsAcquired() const
+  {
+#ifdef MOZ_CALLSTACK_DISABLED
+    return mAcquired;
+#else
+    return !mAcquired.IsEmpty();
+#endif
+  }
+
+  /**
+   * mChainPrev
+   * A series of resource acquisitions creates a chain of orders.  This
+   * chain is implemented as a linked list; |mChainPrev| points to the
+   * resource most recently Acquire()'d before this one.
+   **/
+  BlockingResourceBase* mChainPrev;
+
+private:
+  /**
+   * mName
+   * A descriptive name for this resource.  Used in error
+   * messages etc.
+   */
+  const char* mName;
+
+  /**
+   * mType
+   * The more specific type of this resource.  Used to implement
+   * special semantics (e.g., reentrancy of monitors).
+   **/
+  BlockingResourceType mType;
+
+  /**
+   * mAcquired
+   * Indicates if this resource is currently acquired.
+   */
+  AcquisitionState mAcquired;
+
+#ifndef MOZ_CALLSTACK_DISABLED
+  /**
+   * mFirstSeen
+   * Inidicates where this resource was first acquired.
+   */
+  AcquisitionState mFirstSeen;
+#endif
+
+  /**
+   * sCallOnce
+   * Ensures static members are initialized only once, and in a
+   * thread-safe way.
+   */
+  static PRCallOnceType sCallOnce;
+
+  /**
+   * sResourceAcqnChainFrontTPI
+   * Thread-private index to the front of each thread's resource
+   * acquisition chain.
+   */
+  static unsigned sResourceAcqnChainFrontTPI;
+
+  /**
+   * sDeadlockDetector
+   * Does as named.
+   */
+  static DDT* sDeadlockDetector;
+
+  /**
+   * InitStatics
+   * Inititialize static members of BlockingResourceBase that can't
+   * be statically initialized.
+   *
+   * *NOT* thread safe.
+   */
+  static PRStatus InitStatics();
+
+  /**
+   * Shutdown
+   * Free static members.
+   *
+   * *NOT* thread safe.
+   */
+  static void Shutdown();
+
+  static void StackWalkCallback(uint32_t aFrameNumber, void* aPc,
+                                void* aSp, void* aClosure);
+  static void GetStackTrace(AcquisitionState& aState);
+
+#  ifdef MOZILLA_INTERNAL_API
+  // so it can call BlockingResourceBase::Shutdown()
+  friend void LogTerm();
+#  endif  // ifdef MOZILLA_INTERNAL_API
+
+#else  // non-DEBUG implementation
+
+  BlockingResourceBase(const char* aName, BlockingResourceType aType) {}
+
+  ~BlockingResourceBase() {}
+
+#endif
+};
+
+
+} // namespace mozilla
+
+
+#endif // mozilla_BlockingResourceBase_h
diff --git a/xpcom/glue/CondVar.h b/xpcom/glue/CondVar.h
new file mode 100644
index 000000000..5d05464ec
--- /dev/null
+++ b/xpcom/glue/CondVar.h
@@ -0,0 +1,144 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_CondVar_h
+#define mozilla_CondVar_h
+
+#include "prcvar.h"
+
+#include "mozilla/BlockingResourceBase.h"
+#include "mozilla/Mutex.h"
+
+#ifdef MOZILLA_INTERNAL_API
+#include "GeckoProfiler.h"
+#endif //MOZILLA_INTERNAL_API
+
+namespace mozilla {
+
+
+/**
+ * CondVar
+ * Vanilla condition variable.  Please don't use this unless you have a
+ * compelling reason --- Monitor provides a simpler API.
+ */
+class CondVar : BlockingResourceBase
+{
+public:
+  /**
+   * CondVar
+   *
+   * The CALLER owns |aLock|.
+   *
+   * @param aLock A Mutex to associate with this condition variable.
+   * @param aName A name which can reference this monitor
+   * @returns If failure, nullptr.
+   *          If success, a valid Monitor* which must be destroyed
+   *          by Monitor::DestroyMonitor()
+   **/
+  CondVar(Mutex& aLock, const char* aName)
+    : BlockingResourceBase(aName, eCondVar)
+    , mLock(&aLock)
+  {
+    MOZ_COUNT_CTOR(CondVar);
+    // |aLock| must necessarily already be known to the deadlock detector
+    mCvar = PR_NewCondVar(mLock->mLock);
+    if (!mCvar) {
+      NS_RUNTIMEABORT("Can't allocate mozilla::CondVar");
+    }
+  }
+
+  /**
+   * ~CondVar
+   * Clean up after this CondVar, but NOT its associated Mutex.
+   **/
+  ~CondVar()
+  {
+    NS_ASSERTION(mCvar && mLock,
+                 "improperly constructed CondVar or double free");
+    PR_DestroyCondVar(mCvar);
+    mCvar = 0;
+    mLock = 0;
+    MOZ_COUNT_DTOR(CondVar);
+  }
+
+#ifndef DEBUG
+  /**
+   * Wait
+   * @see prcvar.h
+   **/
+  nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT)
+  {
+
+#ifdef MOZILLA_INTERNAL_API
+    GeckoProfilerSleepRAII profiler_sleep;
+#endif //MOZILLA_INTERNAL_API
+    // NSPR checks for lock ownership
+    return PR_WaitCondVar(mCvar, aInterval) == PR_SUCCESS ? NS_OK :
+                                                            NS_ERROR_FAILURE;
+  }
+#else
+  nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT);
+#endif // ifndef DEBUG
+
+  /**
+   * Notify
+   * @see prcvar.h
+   **/
+  nsresult Notify()
+  {
+    // NSPR checks for lock ownership
+    return PR_NotifyCondVar(mCvar) == PR_SUCCESS ? NS_OK : NS_ERROR_FAILURE;
+  }
+
+  /**
+   * NotifyAll
+   * @see prcvar.h
+   **/
+  nsresult NotifyAll()
+  {
+    // NSPR checks for lock ownership
+    return PR_NotifyAllCondVar(mCvar) == PR_SUCCESS ? NS_OK : NS_ERROR_FAILURE;
+  }
+
+#ifdef DEBUG
+  /**
+   * AssertCurrentThreadOwnsMutex
+   * @see Mutex::AssertCurrentThreadOwns
+   **/
+  void AssertCurrentThreadOwnsMutex()
+  {
+    mLock->AssertCurrentThreadOwns();
+  }
+
+  /**
+   * AssertNotCurrentThreadOwnsMutex
+   * @see Mutex::AssertNotCurrentThreadOwns
+   **/
+  void AssertNotCurrentThreadOwnsMutex()
+  {
+    mLock->AssertNotCurrentThreadOwns();
+  }
+
+#else
+  void AssertCurrentThreadOwnsMutex() {}
+  void AssertNotCurrentThreadOwnsMutex() {}
+
+#endif  // ifdef DEBUG
+
+private:
+  CondVar();
+  CondVar(CondVar&);
+  CondVar& operator=(CondVar&);
+
+  Mutex* mLock;
+  PRCondVar* mCvar;
+};
+
+
+} // namespace mozilla
+
+
+#endif  // ifndef mozilla_CondVar_h  
diff --git a/xpcom/glue/DeadlockDetector.h b/xpcom/glue/DeadlockDetector.h
new file mode 100644
index 000000000..382e4ef4a
--- /dev/null
+++ b/xpcom/glue/DeadlockDetector.h
@@ -0,0 +1,382 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef mozilla_DeadlockDetector_h
+#define mozilla_DeadlockDetector_h
+
+#include "mozilla/Attributes.h"
+
+#include <stdlib.h>
+
+#include "prlock.h"
+
+#include "nsClassHashtable.h"
+#include "nsTArray.h"
+
+namespace mozilla {
+
+/**
+ * DeadlockDetector
+ *
+ * The following is an approximate description of how the deadlock detector
+ * works.
+ *
+ * The deadlock detector ensures that all blocking resources are
+ * acquired according to a partial order P.  One type of blocking
+ * resource is a lock.  If a lock l1 is acquired (locked) before l2,
+ * then we say that |l1 <_P l2|.  The detector flags an error if two
+ * locks l1 and l2 have an inconsistent ordering in P; that is, if
+ * both |l1 <_P l2| and |l2 <_P l1|.  This is a potential error
+ * because a thread acquiring l1,l2 according to the first order might
+ * race with a thread acquiring them according to the second order.
+ * If this happens under the right conditions, then the acquisitions
+ * will deadlock.
+ *
+ * This deadlock detector doesn't know at compile-time what P is.  So,
+ * it tries to discover the order at run time.  More precisely, it
+ * finds <i>some</i> order P, then tries to find chains of resource
+ * acquisitions that violate P.  An example acquisition sequence, and
+ * the orders they impose, is
+ *   l1.lock()   // current chain: [ l1 ]
+ *               // order: { }
+ *
+ *   l2.lock()   // current chain: [ l1, l2 ]
+ *               // order: { l1 <_P l2 }
+ *
+ *   l3.lock()   // current chain: [ l1, l2, l3 ]
+ *               // order: { l1 <_P l2, l2 <_P l3, l1 <_P l3 }
+ *               // (note: <_P is transitive, so also |l1 <_P l3|)
+ *
+ *   l2.unlock() // current chain: [ l1, l3 ]
+ *               // order: { l1 <_P l2, l2 <_P l3, l1 <_P l3 }
+ *               // (note: it's OK, but weird, that l2 was unlocked out
+ *               //  of order.  we still have l1 <_P l3).
+ *
+ *   l2.lock()   // current chain: [ l1, l3, l2 ]
+ *               // order: { l1 <_P l2, l2 <_P l3, l1 <_P l3,
+ *                                      l3 <_P l2 (!!!) }
+ * BEEP BEEP!  Here the detector will flag a potential error, since
+ * l2 and l3 were used inconsistently (and potentially in ways that
+ * would deadlock).
+ */
+template<typename T>
+class DeadlockDetector
+{
+public:
+  typedef nsTArray<const T*> ResourceAcquisitionArray;
+
+private:
+  struct OrderingEntry;
+  typedef nsTArray<OrderingEntry*> HashEntryArray;
+  typedef typename HashEntryArray::index_type index_type;
+  typedef typename HashEntryArray::size_type size_type;
+  static const index_type NoIndex = HashEntryArray::NoIndex;
+
+  /**
+   * Value type for the ordering table.  Contains the other
+   * resources on which an ordering constraint |key < other|
+   * exists.  The catch is that we also store the calling context at
+   * which the other resource was acquired; this improves the
+   * quality of error messages when potential deadlock is detected.
+   */
+  struct OrderingEntry
+  {
+    explicit OrderingEntry(const T* aResource)
+      : mOrderedLT()        // FIXME bug 456272: set to empirical dep size?
+      , mExternalRefs()
+      , mResource(aResource)
+    {
+    }
+    ~OrderingEntry()
+    {
+    }
+
+    size_t
+    SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
+    {
+      size_t n = aMallocSizeOf(this);
+      n += mOrderedLT.ShallowSizeOfExcludingThis(aMallocSizeOf);
+      n += mExternalRefs.ShallowSizeOfExcludingThis(aMallocSizeOf);
+      return n;
+    }
+
+    HashEntryArray mOrderedLT; // this <_o Other
+    HashEntryArray mExternalRefs; // hash entries that reference this
+    const T* mResource;
+  };
+
+  // Throwaway RAII lock to make the following code safer.
+  struct PRAutoLock
+  {
+    explicit PRAutoLock(PRLock* aLock) : mLock(aLock) { PR_Lock(mLock); }
+    ~PRAutoLock() { PR_Unlock(mLock); }
+    PRLock* mLock;
+  };
+
+public:
+  static const uint32_t kDefaultNumBuckets;
+
+  /**
+   * DeadlockDetector
+   * Create a new deadlock detector.
+   *
+   * @param aNumResourcesGuess Guess at approximate number of resources
+   *        that will be checked.
+   */
+  explicit DeadlockDetector(uint32_t aNumResourcesGuess = kDefaultNumBuckets)
+    : mOrdering(aNumResourcesGuess)
+  {
+    mLock = PR_NewLock();
+    if (!mLock) {
+      NS_RUNTIMEABORT("couldn't allocate deadlock detector lock");
+    }
+  }
+
+  /**
+   * ~DeadlockDetector
+   *
+   * *NOT* thread safe.
+   */
+  ~DeadlockDetector()
+  {
+    PR_DestroyLock(mLock);
+  }
+
+  size_t
+  SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
+  {
+    size_t n = aMallocSizeOf(this);
+
+    {
+      PRAutoLock _(mLock);
+      n += mOrdering.ShallowSizeOfExcludingThis(aMallocSizeOf);
+      for (auto iter = mOrdering.ConstIter(); !iter.Done(); iter.Next()) {
+        // NB: Key is accounted for in the entry.
+        n += iter.Data()->SizeOfIncludingThis(aMallocSizeOf);
+      }
+    }
+
+    return n;
+  }
+
+  /**
+   * Add
+   * Make the deadlock detector aware of |aResource|.
+   *
+   * WARNING: The deadlock detector owns |aResource|.
+   *
+   * Thread safe.
+   *
+   * @param aResource Resource to make deadlock detector aware of.
+   */
+  void Add(const T* aResource)
+  {
+    PRAutoLock _(mLock);
+    mOrdering.Put(aResource, new OrderingEntry(aResource));
+  }
+
+  void Remove(const T* aResource)
+  {
+    PRAutoLock _(mLock);
+
+    OrderingEntry* entry = mOrdering.Get(aResource);
+
+    // Iterate the external refs and remove the entry from them.
+    HashEntryArray& refs = entry->mExternalRefs;
+    for (index_type i = 0; i < refs.Length(); i++) {
+      refs[i]->mOrderedLT.RemoveElementSorted(entry);
+    }
+
+    // Iterate orders and remove this entry from their refs.
+    HashEntryArray& orders = entry->mOrderedLT;
+    for (index_type i = 0; i < orders.Length(); i++) {
+      orders[i]->mExternalRefs.RemoveElementSorted(entry);
+    }
+
+    // Now the entry can be safely removed.
+    mOrdering.Remove(aResource);
+  }
+
+  /**
+   * CheckAcquisition This method is called after acquiring |aLast|,
+   * but before trying to acquire |aProposed|.
+   * It determines whether actually trying to acquire |aProposed|
+   * will create problems.  It is OK if |aLast| is nullptr; this is
+   * interpreted as |aProposed| being the thread's first acquisition
+   * of its current chain.
+   *
+   * Iff acquiring |aProposed| may lead to deadlock for some thread
+   * interleaving (including the current one!), the cyclical
+   * dependency from which this was deduced is returned.  Otherwise,
+   * 0 is returned.
+   *
+   * If a potential deadlock is detected and a resource cycle is
+   * returned, it is the *caller's* responsibility to free it.
+   *
+   * Thread safe.
+   *
+   * @param aLast Last resource acquired by calling thread (or 0).
+   * @param aProposed Resource calling thread proposes to acquire.
+   */
+  ResourceAcquisitionArray* CheckAcquisition(const T* aLast,
+                                             const T* aProposed)
+  {
+    if (!aLast) {
+      // don't check if |0 < aProposed|; just vamoose
+      return 0;
+    }
+
+    NS_ASSERTION(aProposed, "null resource");
+    PRAutoLock _(mLock);
+
+    OrderingEntry* proposed = mOrdering.Get(aProposed);
+    NS_ASSERTION(proposed, "missing ordering entry");
+
+    OrderingEntry* current = mOrdering.Get(aLast);
+    NS_ASSERTION(current, "missing ordering entry");
+
+    // this is the crux of the deadlock detector algorithm
+
+    if (current == proposed) {
+      // reflexive deadlock.  fastpath b/c InTransitiveClosure is
+      // not applicable here.
+      ResourceAcquisitionArray* cycle = new ResourceAcquisitionArray();
+      if (!cycle) {
+        NS_RUNTIMEABORT("can't allocate dep. cycle array");
+      }
+      cycle->AppendElement(current->mResource);
+      cycle->AppendElement(aProposed);
+      return cycle;
+    }
+    if (InTransitiveClosure(current, proposed)) {
+      // we've already established |aLast < aProposed|.  all is well.
+      return 0;
+    }
+    if (InTransitiveClosure(proposed, current)) {
+      // the order |aProposed < aLast| has been deduced, perhaps
+      // transitively.  we're attempting to violate that
+      // constraint by acquiring resources in the order
+      // |aLast < aProposed|, and thus we may deadlock under the
+      // right conditions.
+      ResourceAcquisitionArray* cycle = GetDeductionChain(proposed, current);
+      // show how acquiring |aProposed| would complete the cycle
+      cycle->AppendElement(aProposed);
+      return cycle;
+    }
+    // |aLast|, |aProposed| are unordered according to our
+    // poset.  this is fine, but we now need to add this
+    // ordering constraint.
+    current->mOrderedLT.InsertElementSorted(proposed);
+    proposed->mExternalRefs.InsertElementSorted(current);
+    return 0;
+  }
+
+  /**
+   * Return true iff |aTarget| is in the transitive closure of |aStart|
+   * over the ordering relation `<_this'.
+   *
+   * @precondition |aStart != aTarget|
+   */
+  bool InTransitiveClosure(const OrderingEntry* aStart,
+                           const OrderingEntry* aTarget) const
+  {
+    // NB: Using a static comparator rather than default constructing one shows
+    //     a 9% improvement in scalability tests on some systems.
+    static nsDefaultComparator<const OrderingEntry*, const OrderingEntry*> comp;
+    if (aStart->mOrderedLT.BinaryIndexOf(aTarget, comp) != NoIndex) {
+      return true;
+    }
+
+    index_type i = 0;
+    size_type len = aStart->mOrderedLT.Length();
+    for (auto it = aStart->mOrderedLT.Elements(); i < len; ++i, ++it) {
+      if (InTransitiveClosure(*it, aTarget)) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  /**
+   * Return an array of all resource acquisitions
+   *   aStart <_this r1 <_this r2 <_ ... <_ aTarget
+   * from which |aStart <_this aTarget| was deduced, including
+   * |aStart| and |aTarget|.
+   *
+   * Nb: there may be multiple deductions of |aStart <_this
+   * aTarget|.  This function returns the first ordering found by
+   * depth-first search.
+   *
+   * Nb: |InTransitiveClosure| could be replaced by this function.
+   * However, this one is more expensive because we record the DFS
+   * search stack on the heap whereas the other doesn't.
+   *
+   * @precondition |aStart != aTarget|
+   */
+  ResourceAcquisitionArray* GetDeductionChain(const OrderingEntry* aStart,
+                                              const OrderingEntry* aTarget)
+  {
+    ResourceAcquisitionArray* chain = new ResourceAcquisitionArray();
+    if (!chain) {
+      NS_RUNTIMEABORT("can't allocate dep. cycle array");
+    }
+    chain->AppendElement(aStart->mResource);
+
+    NS_ASSERTION(GetDeductionChain_Helper(aStart, aTarget, chain),
+                 "GetDeductionChain called when there's no deadlock");
+    return chain;
+  }
+
+  // precondition: |aStart != aTarget|
+  // invariant: |aStart| is the last element in |aChain|
+  bool GetDeductionChain_Helper(const OrderingEntry* aStart,
+                                const OrderingEntry* aTarget,
+                                ResourceAcquisitionArray* aChain)
+  {
+    if (aStart->mOrderedLT.BinaryIndexOf(aTarget) != NoIndex) {
+      aChain->AppendElement(aTarget->mResource);
+      return true;
+    }
+
+    index_type i = 0;
+    size_type len = aStart->mOrderedLT.Length();
+    for (auto it = aStart->mOrderedLT.Elements(); i < len; ++i, ++it) {
+      aChain->AppendElement((*it)->mResource);
+      if (GetDeductionChain_Helper(*it, aTarget, aChain)) {
+        return true;
+      }
+      aChain->RemoveElementAt(aChain->Length() - 1);
+    }
+    return false;
+  }
+
+  /**
+   * The partial order on resource acquisitions used by the deadlock
+   * detector.
+   */
+  nsClassHashtable<nsPtrHashKey<const T>, OrderingEntry> mOrdering;
+
+
+  /**
+   * Protects contentious methods.
+   * Nb: can't use mozilla::Mutex since we are used as its deadlock
+   * detector.
+   */
+  PRLock* mLock;
+
+private:
+  DeadlockDetector(const DeadlockDetector& aDD) = delete;
+  DeadlockDetector& operator=(const DeadlockDetector& aDD) = delete;
+};
+
+
+template<typename T>
+// FIXME bug 456272: tune based on average workload
+const uint32_t DeadlockDetector<T>::kDefaultNumBuckets = 32;
+
+
+} // namespace mozilla
+
+#endif // ifndef mozilla_DeadlockDetector_h
diff --git a/xpcom/glue/EnumeratedArrayCycleCollection.h b/xpcom/glue/EnumeratedArrayCycleCollection.h
new file mode 100644
index 000000000..faabb5a52
--- /dev/null
+++ b/xpcom/glue/EnumeratedArrayCycleCollection.h
@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef EnumeratedArrayCycleCollection_h_
+#define EnumeratedArrayCycleCollection_h_
+
+#include "mozilla/EnumeratedArray.h"
+#include "nsCycleCollectionTraversalCallback.h"
+
+template<typename IndexType,
+         IndexType SizeAsEnumValue,
+         typename ValueType>
+inline void
+ImplCycleCollectionUnlink(mozilla::EnumeratedArray<IndexType,
+                                                   SizeAsEnumValue,
+                                                   ValueType>& aField)
+{
+  for (size_t i = 0; i < size_t(SizeAsEnumValue); ++i) {
+    aField[IndexType(i)] = nullptr;
+  }
+}
+
+template<typename IndexType,
+         IndexType SizeAsEnumValue,
+         typename ValueType>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            mozilla::EnumeratedArray<IndexType,
+                                                     SizeAsEnumValue,
+                                                     ValueType>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  aFlags |= CycleCollectionEdgeNameArrayFlag;
+  for (size_t i = 0; i < size_t(SizeAsEnumValue); ++i) {
+    ImplCycleCollectionTraverse(aCallback, aField[IndexType(i)], aName, aFlags);
+  }
+}
+
+#endif // EnumeratedArrayCycleCollection_h_
diff --git a/xpcom/glue/FileUtils.cpp b/xpcom/glue/FileUtils.cpp
new file mode 100644
index 000000000..699812461
--- /dev/null
+++ b/xpcom/glue/FileUtils.cpp
@@ -0,0 +1,568 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <errno.h>
+#include <stdio.h>
+
+#include "nscore.h"
+#include "nsStringGlue.h"
+#include "private/pprio.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/FileUtils.h"
+
+#if defined(XP_MACOSX)
+#include <fcntl.h>
+#include <unistd.h>
+#include <mach/machine.h>
+#include <mach-o/fat.h>
+#include <mach-o/loader.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <limits.h>
+#elif defined(XP_UNIX)
+#include <fcntl.h>
+#include <unistd.h>
+#if defined(LINUX)
+#include <elf.h>
+#endif
+#include <sys/types.h>
+#include <sys/stat.h>
+#elif defined(XP_WIN)
+#include <windows.h>
+#endif
+
+// Functions that are not to be used in standalone glue must be implemented
+// within this #if block
+#if !defined(XPCOM_GLUE)
+
+bool
+mozilla::fallocate(PRFileDesc* aFD, int64_t aLength)
+{
+#if defined(HAVE_POSIX_FALLOCATE)
+  return posix_fallocate(PR_FileDesc2NativeHandle(aFD), 0, aLength) == 0;
+#elif defined(XP_WIN)
+  int64_t oldpos = PR_Seek64(aFD, 0, PR_SEEK_CUR);
+  if (oldpos == -1) {
+    return false;
+  }
+
+  if (PR_Seek64(aFD, aLength, PR_SEEK_SET) != aLength) {
+    return false;
+  }
+
+  bool retval = (0 != SetEndOfFile((HANDLE)PR_FileDesc2NativeHandle(aFD)));
+
+  PR_Seek64(aFD, oldpos, PR_SEEK_SET);
+  return retval;
+#elif defined(XP_MACOSX)
+  int fd = PR_FileDesc2NativeHandle(aFD);
+  fstore_t store = {F_ALLOCATECONTIG, F_PEOFPOSMODE, 0, aLength};
+  // Try to get a continous chunk of disk space
+  int ret = fcntl(fd, F_PREALLOCATE, &store);
+  if (ret == -1) {
+    // OK, perhaps we are too fragmented, allocate non-continuous
+    store.fst_flags = F_ALLOCATEALL;
+    ret = fcntl(fd, F_PREALLOCATE, &store);
+    if (ret == -1) {
+      return false;
+    }
+  }
+  return ftruncate(fd, aLength) == 0;
+#elif defined(XP_UNIX)
+  // The following is copied from fcntlSizeHint in sqlite
+  /* If the OS does not have posix_fallocate(), fake it. First use
+  ** ftruncate() to set the file size, then write a single byte to
+  ** the last byte in each block within the extended region. This
+  ** is the same technique used by glibc to implement posix_fallocate()
+  ** on systems that do not have a real fallocate() system call.
+  */
+  int64_t oldpos = PR_Seek64(aFD, 0, PR_SEEK_CUR);
+  if (oldpos == -1) {
+    return false;
+  }
+
+  struct stat buf;
+  int fd = PR_FileDesc2NativeHandle(aFD);
+  if (fstat(fd, &buf)) {
+    return false;
+  }
+
+  if (buf.st_size >= aLength) {
+    return false;
+  }
+
+  const int nBlk = buf.st_blksize;
+
+  if (!nBlk) {
+    return false;
+  }
+
+  if (ftruncate(fd, aLength)) {
+    return false;
+  }
+
+  int nWrite; // Return value from write()
+  int64_t iWrite = ((buf.st_size + 2 * nBlk - 1) / nBlk) * nBlk - 1; // Next offset to write to
+  while (iWrite < aLength) {
+    nWrite = 0;
+    if (PR_Seek64(aFD, iWrite, PR_SEEK_SET) == iWrite) {
+      nWrite = PR_Write(aFD, "", 1);
+    }
+    if (nWrite != 1) {
+      break;
+    }
+    iWrite += nBlk;
+  }
+
+  PR_Seek64(aFD, oldpos, PR_SEEK_SET);
+  return nWrite == 1;
+#endif
+  return false;
+}
+
+#ifdef ReadSysFile_PRESENT
+
+bool
+mozilla::ReadSysFile(
+  const char* aFilename,
+  char* aBuf,
+  size_t aBufSize)
+{
+  int fd = MOZ_TEMP_FAILURE_RETRY(open(aFilename, O_RDONLY));
+  if (fd < 0) {
+    return false;
+  }
+  ScopedClose autoClose(fd);
+  if (aBufSize == 0) {
+    return true;
+  }
+  ssize_t bytesRead;
+  size_t offset = 0;
+  do {
+    bytesRead = MOZ_TEMP_FAILURE_RETRY(read(fd, aBuf + offset,
+                                            aBufSize - offset));
+    if (bytesRead == -1) {
+      return false;
+    }
+    offset += bytesRead;
+  } while (bytesRead > 0 && offset < aBufSize);
+  MOZ_ASSERT(offset <= aBufSize);
+  if (offset > 0 && aBuf[offset - 1] == '\n') {
+    offset--;
+  }
+  if (offset == aBufSize) {
+    MOZ_ASSERT(offset > 0);
+    offset--;
+  }
+  aBuf[offset] = '\0';
+  return true;
+}
+
+bool
+mozilla::ReadSysFile(
+  const char* aFilename,
+  int* aVal)
+{
+  char valBuf[32];
+  if (!ReadSysFile(aFilename, valBuf, sizeof(valBuf))) {
+    return false;
+  }
+  return sscanf(valBuf, "%d", aVal) == 1;
+}
+
+bool
+mozilla::ReadSysFile(
+  const char* aFilename,
+  bool* aVal)
+{
+  int v;
+  if (!ReadSysFile(aFilename, &v)) {
+    return false;
+  }
+  *aVal = (v != 0);
+  return true;
+}
+
+#endif /* ReadSysFile_PRESENT */
+
+#ifdef WriteSysFile_PRESENT
+
+bool
+mozilla::WriteSysFile(
+  const char* aFilename,
+  const char* aBuf)
+{
+  size_t aBufSize = strlen(aBuf);
+  int fd = MOZ_TEMP_FAILURE_RETRY(open(aFilename, O_WRONLY));
+  if (fd < 0) {
+    return false;
+  }
+  ScopedClose autoClose(fd);
+  ssize_t bytesWritten;
+  size_t offset = 0;
+  do {
+    bytesWritten = MOZ_TEMP_FAILURE_RETRY(write(fd, aBuf + offset,
+                                                aBufSize - offset));
+    if (bytesWritten == -1) {
+      return false;
+    }
+    offset += bytesWritten;
+  } while (bytesWritten > 0 && offset < aBufSize);
+  MOZ_ASSERT(offset == aBufSize);
+  return true;
+}
+
+#endif /* WriteSysFile_PRESENT */
+
+void
+mozilla::ReadAheadLib(nsIFile* aFile)
+{
+#if defined(XP_WIN)
+  nsAutoString path;
+  if (!aFile || NS_FAILED(aFile->GetPath(path))) {
+    return;
+  }
+  ReadAheadLib(path.get());
+#elif defined(LINUX) && !defined(ANDROID) || defined(XP_MACOSX)
+  nsAutoCString nativePath;
+  if (!aFile || NS_FAILED(aFile->GetNativePath(nativePath))) {
+    return;
+  }
+  ReadAheadLib(nativePath.get());
+#endif
+}
+
+void
+mozilla::ReadAheadFile(nsIFile* aFile, const size_t aOffset,
+                       const size_t aCount, mozilla::filedesc_t* aOutFd)
+{
+#if defined(XP_WIN)
+  nsAutoString path;
+  if (!aFile || NS_FAILED(aFile->GetPath(path))) {
+    return;
+  }
+  ReadAheadFile(path.get(), aOffset, aCount, aOutFd);
+#elif defined(LINUX) && !defined(ANDROID) || defined(XP_MACOSX)
+  nsAutoCString nativePath;
+  if (!aFile || NS_FAILED(aFile->GetNativePath(nativePath))) {
+    return;
+  }
+  ReadAheadFile(nativePath.get(), aOffset, aCount, aOutFd);
+#endif
+}
+
+#endif // !defined(XPCOM_GLUE)
+
+#if defined(LINUX) && !defined(ANDROID)
+
+static const unsigned int bufsize = 4096;
+
+#ifdef __LP64__
+typedef Elf64_Ehdr Elf_Ehdr;
+typedef Elf64_Phdr Elf_Phdr;
+static const unsigned char ELFCLASS = ELFCLASS64;
+typedef Elf64_Off Elf_Off;
+#else
+typedef Elf32_Ehdr Elf_Ehdr;
+typedef Elf32_Phdr Elf_Phdr;
+static const unsigned char ELFCLASS = ELFCLASS32;
+typedef Elf32_Off Elf_Off;
+#endif
+
+#elif defined(XP_MACOSX)
+
+#if defined(__i386__)
+static const uint32_t CPU_TYPE = CPU_TYPE_X86;
+#elif defined(__x86_64__)
+static const uint32_t CPU_TYPE = CPU_TYPE_X86_64;
+#elif defined(__ppc__)
+static const uint32_t CPU_TYPE = CPU_TYPE_POWERPC;
+#elif defined(__ppc64__)
+static const uint32_t CPU_TYPE = CPU_TYPE_POWERPC64;
+#else
+#error Unsupported CPU type
+#endif
+
+#ifdef __LP64__
+#undef LC_SEGMENT
+#define LC_SEGMENT LC_SEGMENT_64
+#undef MH_MAGIC
+#define MH_MAGIC MH_MAGIC_64
+#define cpu_mach_header mach_header_64
+#define segment_command segment_command_64
+#else
+#define cpu_mach_header mach_header
+#endif
+
+class ScopedMMap
+{
+public:
+  explicit ScopedMMap(const char* aFilePath)
+    : buf(nullptr)
+  {
+    fd = open(aFilePath, O_RDONLY);
+    if (fd < 0) {
+      return;
+    }
+    struct stat st;
+    if (fstat(fd, &st) < 0) {
+      return;
+    }
+    size = st.st_size;
+    buf = (char*)mmap(nullptr, size, PROT_READ, MAP_PRIVATE, fd, 0);
+  }
+  ~ScopedMMap()
+  {
+    if (buf) {
+      munmap(buf, size);
+    }
+    if (fd >= 0) {
+      close(fd);
+    }
+  }
+  operator char*() { return buf; }
+  int getFd() { return fd; }
+private:
+  int fd;
+  char* buf;
+  size_t size;
+};
+#endif
+
+void
+mozilla::ReadAhead(mozilla::filedesc_t aFd, const size_t aOffset,
+                   const size_t aCount)
+{
+#if defined(XP_WIN)
+
+  LARGE_INTEGER fpOriginal;
+  LARGE_INTEGER fpOffset;
+#if defined(HAVE_LONG_LONG)
+  fpOffset.QuadPart = 0;
+#else
+  fpOffset.u.LowPart = 0;
+  fpOffset.u.HighPart = 0;
+#endif
+
+  // Get the current file pointer so that we can restore it. This isn't
+  // really necessary other than to provide the same semantics regarding the
+  // file pointer that other platforms do
+  if (!SetFilePointerEx(aFd, fpOffset, &fpOriginal, FILE_CURRENT)) {
+    return;
+  }
+
+  if (aOffset) {
+#if defined(HAVE_LONG_LONG)
+    fpOffset.QuadPart = static_cast<LONGLONG>(aOffset);
+#else
+    fpOffset.u.LowPart = aOffset;
+    fpOffset.u.HighPart = 0;
+#endif
+
+    if (!SetFilePointerEx(aFd, fpOffset, nullptr, FILE_BEGIN)) {
+      return;
+    }
+  }
+
+  char buf[64 * 1024];
+  size_t totalBytesRead = 0;
+  DWORD dwBytesRead;
+  // Do dummy reads to trigger kernel-side readhead via FILE_FLAG_SEQUENTIAL_SCAN.
+  // Abort when underfilling because during testing the buffers are read fully
+  // A buffer that's not keeping up would imply that readahead isn't working right
+  while (totalBytesRead < aCount &&
+         ReadFile(aFd, buf, sizeof(buf), &dwBytesRead, nullptr) &&
+         dwBytesRead == sizeof(buf)) {
+    totalBytesRead += dwBytesRead;
+  }
+
+  // Restore the file pointer
+  SetFilePointerEx(aFd, fpOriginal, nullptr, FILE_BEGIN);
+
+#elif defined(LINUX) && !defined(ANDROID)
+
+  readahead(aFd, aOffset, aCount);
+
+#elif defined(XP_MACOSX)
+
+  struct radvisory ra;
+  ra.ra_offset = aOffset;
+  ra.ra_count = aCount;
+  // The F_RDADVISE fcntl is equivalent to Linux' readahead() system call.
+  fcntl(aFd, F_RDADVISE, &ra);
+
+#endif
+}
+
+void
+mozilla::ReadAheadLib(mozilla::pathstr_t aFilePath)
+{
+  if (!aFilePath) {
+    return;
+  }
+#if defined(XP_WIN)
+  ReadAheadFile(aFilePath);
+#elif defined(LINUX) && !defined(ANDROID)
+  int fd = open(aFilePath, O_RDONLY);
+  if (fd < 0) {
+    return;
+  }
+
+  union
+  {
+    char buf[bufsize];
+    Elf_Ehdr ehdr;
+  } elf;
+  // Read ELF header (ehdr) and program header table (phdr).
+  // We check that the ELF magic is found, that the ELF class matches
+  // our own, and that the program header table as defined in the ELF
+  // headers fits in the buffer we read.
+  if ((read(fd, elf.buf, bufsize) <= 0) ||
+      (memcmp(elf.buf, ELFMAG, 4)) ||
+      (elf.ehdr.e_ident[EI_CLASS] != ELFCLASS) ||
+      // Upcast e_phentsize so the multiplication is done in the same precision
+      // as the subsequent addition, to satisfy static analyzers and avoid
+      // issues with abnormally large program header tables.
+      (elf.ehdr.e_phoff + (static_cast<Elf_Off>(elf.ehdr.e_phentsize) *
+                           elf.ehdr.e_phnum) >= bufsize)) {
+    close(fd);
+    return;
+  }
+  // The program header table contains segment definitions. One such
+  // segment type is PT_LOAD, which describes how the dynamic loader
+  // is going to map the file in memory. We use that information to
+  // find the biggest offset from the library that will be mapped in
+  // memory.
+  Elf_Phdr* phdr = (Elf_Phdr*)&elf.buf[elf.ehdr.e_phoff];
+  Elf_Off end = 0;
+  for (int phnum = elf.ehdr.e_phnum; phnum; phdr++, phnum--) {
+    if ((phdr->p_type == PT_LOAD) &&
+        (end < phdr->p_offset + phdr->p_filesz)) {
+      end = phdr->p_offset + phdr->p_filesz;
+    }
+  }
+  // Let the kernel read ahead what the dynamic loader is going to
+  // map in memory soon after.
+  if (end > 0) {
+    ReadAhead(fd, 0, end);
+  }
+  close(fd);
+#elif defined(XP_MACOSX)
+  ScopedMMap buf(aFilePath);
+  char* base = buf;
+  if (!base) {
+    return;
+  }
+
+  // An OSX binary might either be a fat (universal) binary or a
+  // Mach-O binary. A fat binary actually embeds several Mach-O
+  // binaries. If we have a fat binary, find the offset where the
+  // Mach-O binary for our CPU type can be found.
+  struct fat_header* fh = (struct fat_header*)base;
+
+  if (OSSwapBigToHostInt32(fh->magic) == FAT_MAGIC) {
+    uint32_t nfat_arch = OSSwapBigToHostInt32(fh->nfat_arch);
+    struct fat_arch* arch = (struct fat_arch*)&buf[sizeof(struct fat_header)];
+    for (; nfat_arch; arch++, nfat_arch--) {
+      if (OSSwapBigToHostInt32(arch->cputype) == CPU_TYPE) {
+        base += OSSwapBigToHostInt32(arch->offset);
+        break;
+      }
+    }
+    if (base == buf) {
+      return;
+    }
+  }
+
+  // Check Mach-O magic in the Mach header
+  struct cpu_mach_header* mh = (struct cpu_mach_header*)base;
+  if (mh->magic != MH_MAGIC) {
+    return;
+  }
+
+  // The Mach header is followed by a sequence of load commands.
+  // Each command has a header containing the command type and the
+  // command size. LD_SEGMENT commands describes how the dynamic
+  // loader is going to map the file in memory. We use that
+  // information to find the biggest offset from the library that
+  // will be mapped in memory.
+  char* cmd = &base[sizeof(struct cpu_mach_header)];
+  uint32_t end = 0;
+  for (uint32_t ncmds = mh->ncmds; ncmds; ncmds--) {
+    struct segment_command* sh = (struct segment_command*)cmd;
+    if (sh->cmd != LC_SEGMENT) {
+      continue;
+    }
+    if (end < sh->fileoff + sh->filesize) {
+      end = sh->fileoff + sh->filesize;
+    }
+    cmd += sh->cmdsize;
+  }
+  // Let the kernel read ahead what the dynamic loader is going to
+  // map in memory soon after.
+  if (end > 0) {
+    ReadAhead(buf.getFd(), base - buf, end);
+  }
+#endif
+}
+
+void
+mozilla::ReadAheadFile(mozilla::pathstr_t aFilePath, const size_t aOffset,
+                       const size_t aCount, mozilla::filedesc_t* aOutFd)
+{
+#if defined(XP_WIN)
+  if (!aFilePath) {
+    if (aOutFd) {
+      *aOutFd = INVALID_HANDLE_VALUE;
+    }
+    return;
+  }
+  HANDLE fd = CreateFileW(aFilePath, GENERIC_READ, FILE_SHARE_READ, nullptr,
+                          OPEN_EXISTING, FILE_FLAG_SEQUENTIAL_SCAN, nullptr);
+  if (aOutFd) {
+    *aOutFd = fd;
+  }
+  if (fd == INVALID_HANDLE_VALUE) {
+    return;
+  }
+  ReadAhead(fd, aOffset, aCount);
+  if (!aOutFd) {
+    CloseHandle(fd);
+  }
+#elif defined(LINUX) && !defined(ANDROID) || defined(XP_MACOSX)
+  if (!aFilePath) {
+    if (aOutFd) {
+      *aOutFd = -1;
+    }
+    return;
+  }
+  int fd = open(aFilePath, O_RDONLY);
+  if (aOutFd) {
+    *aOutFd = fd;
+  }
+  if (fd < 0) {
+    return;
+  }
+  size_t count;
+  if (aCount == SIZE_MAX) {
+    struct stat st;
+    if (fstat(fd, &st) < 0) {
+      if (!aOutFd) {
+        close(fd);
+      }
+      return;
+    }
+    count = st.st_size;
+  } else {
+    count = aCount;
+  }
+  ReadAhead(fd, aOffset, count);
+  if (!aOutFd) {
+    close(fd);
+  }
+#endif
+}
+
diff --git a/xpcom/glue/FileUtils.h b/xpcom/glue/FileUtils.h
new file mode 100644
index 000000000..aaf912b21
--- /dev/null
+++ b/xpcom/glue/FileUtils.h
@@ -0,0 +1,220 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_FileUtils_h
+#define mozilla_FileUtils_h
+
+#include "nscore.h" // nullptr
+
+#if defined(XP_UNIX)
+# include <unistd.h>
+#elif defined(XP_WIN)
+# include <io.h>
+#endif
+#include "prio.h"
+
+#include "mozilla/Scoped.h"
+#include "nsIFile.h"
+#include <errno.h>
+#include <limits.h>
+
+namespace mozilla {
+
+#if defined(XP_WIN)
+typedef void* filedesc_t;
+typedef const wchar_t* pathstr_t;
+#else
+typedef int filedesc_t;
+typedef const char* pathstr_t;
+#endif
+
+/**
+ * ScopedCloseFD is a RAII wrapper for POSIX file descriptors
+ *
+ * Instances |close()| their fds when they go out of scope.
+ */
+struct ScopedCloseFDTraits
+{
+  typedef int type;
+  static type empty() { return -1; }
+  static void release(type aFd)
+  {
+    if (aFd != -1) {
+      while (close(aFd) == -1 && errno == EINTR) {
+      }
+    }
+  }
+};
+typedef Scoped<ScopedCloseFDTraits> ScopedClose;
+
+#if !defined(XPCOM_GLUE)
+
+/**
+ * AutoFDClose is a RAII wrapper for PRFileDesc.
+ *
+ * Instances |PR_Close| their fds when they go out of scope.
+ **/
+struct ScopedClosePRFDTraits
+{
+  typedef PRFileDesc* type;
+  static type empty() { return nullptr; }
+  static void release(type aFd)
+  {
+    if (aFd) {
+      PR_Close(aFd);
+    }
+  }
+};
+typedef Scoped<ScopedClosePRFDTraits> AutoFDClose;
+
+/* RAII wrapper for FILE descriptors */
+struct ScopedCloseFileTraits
+{
+  typedef FILE* type;
+  static type empty() { return nullptr; }
+  static void release(type aFile)
+  {
+    if (aFile) {
+      fclose(aFile);
+    }
+  }
+};
+typedef Scoped<ScopedCloseFileTraits> ScopedCloseFile;
+
+/**
+ * Fallocate efficiently and continuously allocates files via fallocate-type APIs.
+ * This is useful for avoiding fragmentation.
+ * On sucess the file be padded with zeros to grow to aLength.
+ *
+ * @param aFD file descriptor.
+ * @param aLength length of file to grow to.
+ * @return true on success.
+ */
+bool fallocate(PRFileDesc* aFD, int64_t aLength);
+
+/**
+ * Use readahead to preload shared libraries into the file cache before loading.
+ * WARNING: This function should not be used without a telemetry field trial
+ *          demonstrating a clear performance improvement!
+ *
+ * @param aFile nsIFile representing path to shared library
+ */
+void ReadAheadLib(nsIFile* aFile);
+
+/**
+ * Use readahead to preload a file into the file cache before reading.
+ * WARNING: This function should not be used without a telemetry field trial
+ *          demonstrating a clear performance improvement!
+ *
+ * @param aFile nsIFile representing path to shared library
+ * @param aOffset Offset into the file to begin preloading
+ * @param aCount Number of bytes to preload (SIZE_MAX implies file size)
+ * @param aOutFd Pointer to file descriptor. If specified, ReadAheadFile will
+ *        return its internal, opened file descriptor instead of closing it.
+ */
+void ReadAheadFile(nsIFile* aFile, const size_t aOffset = 0,
+                   const size_t aCount = SIZE_MAX,
+                   filedesc_t* aOutFd = nullptr);
+
+#endif // !defined(XPCOM_GLUE)
+
+/**
+ * Use readahead to preload shared libraries into the file cache before loading.
+ * WARNING: This function should not be used without a telemetry field trial
+ *          demonstrating a clear performance improvement!
+ *
+ * @param aFilePath path to shared library
+ */
+void ReadAheadLib(pathstr_t aFilePath);
+
+/**
+ * Use readahead to preload a file into the file cache before loading.
+ * WARNING: This function should not be used without a telemetry field trial
+ *          demonstrating a clear performance improvement!
+ *
+ * @param aFilePath path to shared library
+ * @param aOffset Offset into the file to begin preloading
+ * @param aCount Number of bytes to preload (SIZE_MAX implies file size)
+ * @param aOutFd Pointer to file descriptor. If specified, ReadAheadFile will
+ *        return its internal, opened file descriptor instead of closing it.
+ */
+void ReadAheadFile(pathstr_t aFilePath, const size_t aOffset = 0,
+                   const size_t aCount = SIZE_MAX,
+                   filedesc_t* aOutFd = nullptr);
+
+/**
+ * Use readahead to preload a file into the file cache before reading.
+ * When this function exits, the file pointer is guaranteed to be in the same
+ * position it was in before this function was called.
+ * WARNING: This function should not be used without a telemetry field trial
+ *          demonstrating a clear performance improvement!
+ *
+ * @param aFd file descriptor opened for read access
+ * (on Windows, file must be opened with FILE_FLAG_SEQUENTIAL_SCAN)
+ * @param aOffset Offset into the file to begin preloading
+ * @param aCount Number of bytes to preload (SIZE_MAX implies file size)
+ */
+void ReadAhead(filedesc_t aFd, const size_t aOffset = 0,
+               const size_t aCount = SIZE_MAX);
+
+
+#if defined(MOZ_WIDGET_GONK) || defined(XP_UNIX)
+#define MOZ_TEMP_FAILURE_RETRY(exp) (__extension__({ \
+  typeof (exp) _rc; \
+  do { \
+    _rc = (exp); \
+  } while (_rc == -1 && errno == EINTR); \
+  _rc; \
+}))
+#endif
+
+/* Define ReadSysFile() and WriteSysFile() only on GONK to avoid unnecessary
+ * libxul bloat. Also define it in debug builds, so that unit tests for it can
+ * be written and run in non-GONK builds. */
+#if (defined(MOZ_WIDGET_GONK) || defined(DEBUG)) && defined(XP_UNIX)
+
+#ifndef ReadSysFile_PRESENT
+#define ReadSysFile_PRESENT
+#endif /* ReadSysFile_PRESENT */
+
+#ifndef WriteSysFile_PRESENT
+#define WriteSysFile_PRESENT
+#endif /* WriteSysFile_PRESENT */
+
+/**
+ * Read the contents of a file.
+ * This function is intended for reading a single-lined text files from
+ * /sys/. If the file ends with a newline ('\n') then it will be discarded.
+ * The output buffer will always be '\0'-terminated on successful completion.
+ * If aBufSize == 0, then this function will return true if the file exists
+ * and is readable (it will not attempt to read anything from it).
+ * On failure the contents of aBuf after this call will be undefined and the
+ * value of the global variable errno will be set accordingly.
+ * @return true on success, notice that less than requested bytes could have
+ * been read if the file was smaller
+ */
+bool ReadSysFile(const char* aFilename, char* aBuf, size_t aBufSize);
+
+/**
+ * Parse the contents of a file, assuming it contains a decimal integer.
+ * @return true on success
+ */
+bool ReadSysFile(const char* aFilename, int* aVal);
+
+/**
+ * Parse the contents of a file, assuming it contains a boolean value
+ * (either 0 or 1).
+ * @return true on success
+ */
+bool ReadSysFile(const char* aFilename, bool* aVal);
+
+bool WriteSysFile(const char* aFilename, const char* aBuf);
+
+#endif /* (MOZ_WIDGET_GONK || DEBUG) && XP_UNIX */
+
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/glue/GenericFactory.cpp b/xpcom/glue/GenericFactory.cpp
new file mode 100644
index 000000000..5bf0b97a4
--- /dev/null
+++ b/xpcom/glue/GenericFactory.cpp
@@ -0,0 +1,27 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/GenericFactory.h"
+
+namespace mozilla {
+
+NS_IMPL_ISUPPORTS(GenericFactory, nsIFactory)
+
+NS_IMETHODIMP
+GenericFactory::CreateInstance(nsISupports* aOuter, REFNSIID aIID,
+                               void** aResult)
+{
+  return mCtor(aOuter, aIID, aResult);
+}
+
+NS_IMETHODIMP
+GenericFactory::LockFactory(bool aLock)
+{
+  NS_ERROR("Vestigial method, never called!");
+  return NS_ERROR_FAILURE;
+}
+
+} // namespace mozilla
diff --git a/xpcom/glue/GenericFactory.h b/xpcom/glue/GenericFactory.h
new file mode 100644
index 000000000..4561f2a2d
--- /dev/null
+++ b/xpcom/glue/GenericFactory.h
@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_GenericFactory_h
+#define mozilla_GenericFactory_h
+
+#include "mozilla/Attributes.h"
+
+#include "mozilla/Module.h"
+
+namespace mozilla {
+
+/**
+ * A generic factory which uses a constructor function to create instances.
+ * This class is intended for use by the component manager and the generic
+ * module.
+ */
+class GenericFactory final : public nsIFactory
+{
+  ~GenericFactory() {}
+
+public:
+  typedef Module::ConstructorProcPtr ConstructorProcPtr;
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIFACTORY
+
+  explicit GenericFactory(ConstructorProcPtr aCtor)
+    : mCtor(aCtor)
+  {
+    NS_ASSERTION(mCtor, "GenericFactory with no constructor");
+  }
+
+private:
+  ConstructorProcPtr mCtor;
+};
+
+} // namespace mozilla
+
+#endif // mozilla_GenericFactory_h
diff --git a/xpcom/glue/GenericModule.cpp b/xpcom/glue/GenericModule.cpp
new file mode 100644
index 000000000..0b5cd3a7c
--- /dev/null
+++ b/xpcom/glue/GenericModule.cpp
@@ -0,0 +1,98 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ModuleUtils.h"
+#include "mozilla/GenericFactory.h"
+
+#include "nsICategoryManager.h"
+#include "nsIComponentManager.h"
+#include "nsIComponentRegistrar.h"
+#include "nsServiceManagerUtils.h"
+#include "nsXPCOMCID.h"
+#include "nsStringAPI.h"
+
+namespace mozilla {
+
+NS_IMPL_ISUPPORTS(GenericModule, nsIModule)
+
+NS_IMETHODIMP
+GenericModule::GetClassObject(nsIComponentManager* aCompMgr,
+                              const nsCID& aCID,
+                              const nsIID& aIID,
+                              void** aResult)
+{
+  for (const Module::CIDEntry* e = mData->mCIDs; e->cid; ++e) {
+    if (e->cid->Equals(aCID)) {
+      nsCOMPtr<nsIFactory> f;
+      if (e->getFactoryProc) {
+        f = e->getFactoryProc(*mData, *e);
+      } else {
+        NS_ASSERTION(e->constructorProc, "No constructor proc?");
+        f = new GenericFactory(e->constructorProc);
+      }
+      if (!f) {
+        return NS_ERROR_FAILURE;
+      }
+
+      return f->QueryInterface(aIID, aResult);
+    }
+  }
+  NS_ERROR("Asking a module for a CID it doesn't implement.");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+GenericModule::RegisterSelf(nsIComponentManager* aCompMgr,
+                            nsIFile* aLocation,
+                            const char* aLoaderStr,
+                            const char* aType)
+{
+  nsCOMPtr<nsIComponentRegistrar> registrar = do_QueryInterface(aCompMgr);
+  for (const Module::CIDEntry* e = mData->mCIDs; e->cid; ++e) {
+    registrar->RegisterFactoryLocation(*e->cid, "", nullptr, aLocation,
+                                       aLoaderStr, aType);
+  }
+
+  for (const Module::ContractIDEntry* e = mData->mContractIDs;
+       e && e->contractid;
+       ++e) {
+    registrar->RegisterFactoryLocation(*e->cid, "", e->contractid, aLocation,
+                                       aLoaderStr, aType);
+  }
+
+  nsCOMPtr<nsICategoryManager> catman;
+  for (const Module::CategoryEntry* e = mData->mCategoryEntries;
+       e && e->category;
+       ++e) {
+    if (!catman) {
+      catman = do_GetService(NS_CATEGORYMANAGER_CONTRACTID);
+    }
+
+    nsAutoCString prevValue;
+    catman->AddCategoryEntry(e->category, e->entry, e->value, true, true,
+                             getter_Copies(prevValue));
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+GenericModule::UnregisterSelf(nsIComponentManager* aCompMgr,
+                              nsIFile* aFile,
+                              const char* aLoaderStr)
+{
+  NS_ERROR("Nobody should ever call UnregisterSelf!");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+GenericModule::CanUnload(nsIComponentManager* aCompMgr, bool* aResult)
+{
+  NS_ERROR("Nobody should ever call CanUnload!");
+  *aResult = false;
+  return NS_OK;
+}
+
+} // namespace mozilla
diff --git a/xpcom/glue/IntentionalCrash.h b/xpcom/glue/IntentionalCrash.h
new file mode 100644
index 000000000..d01006dff
--- /dev/null
+++ b/xpcom/glue/IntentionalCrash.h
@@ -0,0 +1,58 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <string>
+#include <sstream>
+#include <stdlib.h>
+#include <stdio.h>
+
+#ifdef XP_WIN
+#include <process.h>
+#define getpid _getpid
+#else
+#include <unistd.h>
+#endif
+
+#ifndef mozilla_IntentionalCrash_h
+#define mozilla_IntentionalCrash_h
+
+namespace mozilla {
+
+inline void
+NoteIntentionalCrash(const char* aProcessType)
+{
+  char* f = getenv("XPCOM_MEM_BLOAT_LOG");
+  if (!f) {
+    return;
+  }
+
+  fprintf(stderr, "XPCOM_MEM_BLOAT_LOG: %s\n", f);
+
+  std::string bloatLog(f);
+
+  bool hasExt = false;
+  if (bloatLog.size() >= 4 &&
+      bloatLog.compare(bloatLog.size() - 4, 4, ".log", 4) == 0) {
+    hasExt = true;
+    bloatLog.erase(bloatLog.size() - 4, 4);
+  }
+
+  std::ostringstream bloatName;
+  bloatName << bloatLog << "_" << aProcessType << "_pid" << getpid();
+  if (hasExt) {
+    bloatName << ".log";
+  }
+
+  fprintf(stderr, "Writing to log: %s\n", bloatName.str().c_str());
+
+  FILE* processfd = fopen(bloatName.str().c_str(), "a");
+  fprintf(processfd, "==> process %d will purposefully crash\n", getpid());
+  fclose(processfd);
+}
+
+} // namespace mozilla
+
+#endif // mozilla_IntentionalCrash_h
diff --git a/xpcom/glue/MainThreadUtils.h b/xpcom/glue/MainThreadUtils.h
new file mode 100644
index 000000000..8d76f84ec
--- /dev/null
+++ b/xpcom/glue/MainThreadUtils.h
@@ -0,0 +1,42 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MainThreadUtils_h_
+#define MainThreadUtils_h_
+
+#include "nscore.h"
+
+class nsIThread;
+
+/**
+ * Get a reference to the main thread.
+ *
+ * @param aResult
+ *   The resulting nsIThread object.
+ */
+extern nsresult NS_GetMainThread(nsIThread** aResult);
+
+#ifdef MOZILLA_INTERNAL_API
+// Fast access to the current thread.  Do not release the returned pointer!  If
+// you want to use this pointer from some other thread, then you will need to
+// AddRef it.  Otherwise, you should only consider this pointer valid from code
+// running on the current thread.
+extern nsIThread* NS_GetCurrentThread();
+#endif
+
+#ifdef MOZILLA_INTERNAL_API
+bool NS_IsMainThread();
+#else
+/**
+ * Test to see if the current thread is the main thread.
+ *
+ * @returns true if the current thread is the main thread, and false
+ * otherwise.
+ */
+extern bool NS_IsMainThread();
+#endif
+
+#endif // MainThreadUtils_h_
diff --git a/xpcom/glue/Monitor.h b/xpcom/glue/Monitor.h
new file mode 100644
index 000000000..60750acb3
--- /dev/null
+++ b/xpcom/glue/Monitor.h
@@ -0,0 +1,135 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_Monitor_h
+#define mozilla_Monitor_h
+
+#include "mozilla/CondVar.h"
+#include "mozilla/Mutex.h"
+
+namespace mozilla {
+
+/**
+ * Monitor provides a *non*-reentrant monitor: *not* a Java-style
+ * monitor.  If your code needs support for reentrancy, use
+ * ReentrantMonitor instead.  (Rarely should reentrancy be needed.)
+ *
+ * Instead of directly calling Monitor methods, it's safer and simpler
+ * to instead use the RAII wrappers MonitorAutoLock and
+ * MonitorAutoUnlock.
+ */
+class Monitor
+{
+public:
+  explicit Monitor(const char* aName)
+    : mMutex(aName)
+    , mCondVar(mMutex, "[Monitor.mCondVar]")
+  {
+  }
+
+  ~Monitor() {}
+
+  void Lock() { mMutex.Lock(); }
+  void Unlock() { mMutex.Unlock(); }
+
+  nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT)
+  {
+    return mCondVar.Wait(aInterval);
+  }
+
+  nsresult Notify() { return mCondVar.Notify(); }
+  nsresult NotifyAll() { return mCondVar.NotifyAll(); }
+
+  void AssertCurrentThreadOwns() const
+  {
+    mMutex.AssertCurrentThreadOwns();
+  }
+
+  void AssertNotCurrentThreadOwns() const
+  {
+    mMutex.AssertNotCurrentThreadOwns();
+  }
+
+private:
+  Monitor();
+  Monitor(const Monitor&);
+  Monitor& operator=(const Monitor&);
+
+  Mutex mMutex;
+  CondVar mCondVar;
+};
+
+/**
+ * Lock the monitor for the lexical scope instances of this class are
+ * bound to (except for MonitorAutoUnlock in nested scopes).
+ *
+ * The monitor must be unlocked when instances of this class are
+ * created.
+ */
+class MOZ_STACK_CLASS MonitorAutoLock
+{
+public:
+  explicit MonitorAutoLock(Monitor& aMonitor)
+    : mMonitor(&aMonitor)
+  {
+    mMonitor->Lock();
+  }
+
+  ~MonitorAutoLock()
+  {
+    mMonitor->Unlock();
+  }
+
+  nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT)
+  {
+    return mMonitor->Wait(aInterval);
+  }
+
+  nsresult Notify() { return mMonitor->Notify(); }
+  nsresult NotifyAll() { return mMonitor->NotifyAll(); }
+
+private:
+  MonitorAutoLock();
+  MonitorAutoLock(const MonitorAutoLock&);
+  MonitorAutoLock& operator=(const MonitorAutoLock&);
+  static void* operator new(size_t) CPP_THROW_NEW;
+
+  Monitor* mMonitor;
+};
+
+/**
+ * Unlock the monitor for the lexical scope instances of this class
+ * are bound to (except for MonitorAutoLock in nested scopes).
+ *
+ * The monitor must be locked by the current thread when instances of
+ * this class are created.
+ */
+class MOZ_STACK_CLASS MonitorAutoUnlock
+{
+public:
+  explicit MonitorAutoUnlock(Monitor& aMonitor)
+    : mMonitor(&aMonitor)
+  {
+    mMonitor->Unlock();
+  }
+
+  ~MonitorAutoUnlock()
+  {
+    mMonitor->Lock();
+  }
+
+private:
+  MonitorAutoUnlock();
+  MonitorAutoUnlock(const MonitorAutoUnlock&);
+  MonitorAutoUnlock& operator=(const MonitorAutoUnlock&);
+  static void* operator new(size_t) CPP_THROW_NEW;
+
+  Monitor* mMonitor;
+};
+
+} // namespace mozilla
+
+#endif // mozilla_Monitor_h
diff --git a/xpcom/glue/Mutex.h b/xpcom/glue/Mutex.h
new file mode 100644
index 000000000..16ad44f4c
--- /dev/null
+++ b/xpcom/glue/Mutex.h
@@ -0,0 +1,229 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_Mutex_h
+#define mozilla_Mutex_h
+
+#include "prlock.h"
+
+#include "mozilla/BlockingResourceBase.h"
+#include "mozilla/GuardObjects.h"
+
+//
+// Provides:
+//
+//  - Mutex, a non-recursive mutex
+//  - MutexAutoLock, an RAII class for ensuring that Mutexes are properly
+//    locked and unlocked
+//  - MutexAutoUnlock, complementary sibling to MutexAutoLock
+//
+//  - OffTheBooksMutex, a non-recursive mutex that doesn't do leak checking
+//  - OffTheBooksMutexAuto{Lock,Unlock} - Like MutexAuto{Lock,Unlock}, but for
+//    an OffTheBooksMutex.
+//
+// Using MutexAutoLock/MutexAutoUnlock etc. is MUCH preferred to making bare
+// calls to Lock and Unlock.
+//
+namespace mozilla {
+
+/**
+ * OffTheBooksMutex is identical to Mutex, except that OffTheBooksMutex doesn't
+ * include leak checking.  Sometimes you want to intentionally "leak" a mutex
+ * until shutdown; in these cases, OffTheBooksMutex is for you.
+ */
+class OffTheBooksMutex : BlockingResourceBase
+{
+public:
+  /**
+   * @param aName A name which can reference this lock
+   * @returns If failure, nullptr
+   *          If success, a valid Mutex* which must be destroyed
+   *          by Mutex::DestroyMutex()
+   **/
+  explicit OffTheBooksMutex(const char* aName)
+    : BlockingResourceBase(aName, eMutex)
+  {
+    mLock = PR_NewLock();
+    if (!mLock) {
+      NS_RUNTIMEABORT("Can't allocate mozilla::Mutex");
+    }
+  }
+
+  ~OffTheBooksMutex()
+  {
+    NS_ASSERTION(mLock,
+                 "improperly constructed Lock or double free");
+    // NSPR does consistency checks for us
+    PR_DestroyLock(mLock);
+    mLock = 0;
+  }
+
+#ifndef DEBUG
+  /**
+   * Lock
+   * @see prlock.h
+   **/
+  void Lock() { PR_Lock(mLock); }
+
+  /**
+   * Unlock
+   * @see prlock.h
+   **/
+  void Unlock() { PR_Unlock(mLock); }
+
+  /**
+   * AssertCurrentThreadOwns
+   * @see prlock.h
+   **/
+  void AssertCurrentThreadOwns() const {}
+
+  /**
+   * AssertNotCurrentThreadOwns
+   * @see prlock.h
+   **/
+  void AssertNotCurrentThreadOwns() const {}
+
+#else
+  void Lock();
+  void Unlock();
+
+  void AssertCurrentThreadOwns() const
+  {
+    PR_ASSERT_CURRENT_THREAD_OWNS_LOCK(mLock);
+  }
+
+  void AssertNotCurrentThreadOwns() const
+  {
+    // FIXME bug 476536
+  }
+
+#endif  // ifndef DEBUG
+
+private:
+  OffTheBooksMutex();
+  OffTheBooksMutex(const OffTheBooksMutex&);
+  OffTheBooksMutex& operator=(const OffTheBooksMutex&);
+
+  PRLock* mLock;
+
+  friend class CondVar;
+
+  // MozPromise needs to access mLock for debugging purpose.
+  template<typename, typename, bool>
+  friend class MozPromise;
+};
+
+/**
+ * Mutex
+ * When possible, use MutexAutoLock/MutexAutoUnlock to lock/unlock this
+ * mutex within a scope, instead of calling Lock/Unlock directly.
+ */
+class Mutex : public OffTheBooksMutex
+{
+public:
+  explicit Mutex(const char* aName)
+    : OffTheBooksMutex(aName)
+  {
+    MOZ_COUNT_CTOR(Mutex);
+  }
+
+  ~Mutex()
+  {
+    MOZ_COUNT_DTOR(Mutex);
+  }
+
+private:
+  Mutex();
+  Mutex(const Mutex&);
+  Mutex& operator=(const Mutex&);
+};
+
+/**
+ * MutexAutoLock
+ * Acquires the Mutex when it enters scope, and releases it when it leaves
+ * scope.
+ *
+ * MUCH PREFERRED to bare calls to Mutex.Lock and Unlock.
+ */
+template<typename T>
+class MOZ_RAII BaseAutoLock
+{
+public:
+  /**
+   * Constructor
+   * The constructor aquires the given lock.  The destructor
+   * releases the lock.
+   *
+   * @param aLock A valid mozilla::Mutex* returned by
+   *              mozilla::Mutex::NewMutex.
+   **/
+  explicit BaseAutoLock(T& aLock MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
+    : mLock(&aLock)
+  {
+    MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+    NS_ASSERTION(mLock, "null mutex");
+    mLock->Lock();
+  }
+
+  ~BaseAutoLock(void)
+  {
+    mLock->Unlock();
+  }
+
+private:
+  BaseAutoLock();
+  BaseAutoLock(BaseAutoLock&);
+  BaseAutoLock& operator=(BaseAutoLock&);
+  static void* operator new(size_t) CPP_THROW_NEW;
+
+  T* mLock;
+  MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
+};
+
+typedef BaseAutoLock<Mutex> MutexAutoLock;
+typedef BaseAutoLock<OffTheBooksMutex> OffTheBooksMutexAutoLock;
+
+/**
+ * MutexAutoUnlock
+ * Releases the Mutex when it enters scope, and re-acquires it when it leaves
+ * scope.
+ *
+ * MUCH PREFERRED to bare calls to Mutex.Unlock and Lock.
+ */
+template<typename T>
+class MOZ_RAII BaseAutoUnlock
+{
+public:
+  explicit BaseAutoUnlock(T& aLock MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
+    : mLock(&aLock)
+  {
+    MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+    NS_ASSERTION(mLock, "null lock");
+    mLock->Unlock();
+  }
+
+  ~BaseAutoUnlock()
+  {
+    mLock->Lock();
+  }
+
+private:
+  BaseAutoUnlock();
+  BaseAutoUnlock(BaseAutoUnlock&);
+  BaseAutoUnlock& operator=(BaseAutoUnlock&);
+  static void* operator new(size_t) CPP_THROW_NEW;
+
+  T* mLock;
+  MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
+};
+
+typedef BaseAutoUnlock<Mutex> MutexAutoUnlock;
+typedef BaseAutoUnlock<OffTheBooksMutex> OffTheBooksMutexAutoUnlock;
+
+} // namespace mozilla
+
+
+#endif // ifndef mozilla_Mutex_h
diff --git a/xpcom/glue/Observer.h b/xpcom/glue/Observer.h
new file mode 100644
index 000000000..958e5e4a9
--- /dev/null
+++ b/xpcom/glue/Observer.h
@@ -0,0 +1,83 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_Observer_h
+#define mozilla_Observer_h
+
+#include "nsTArray.h"
+
+namespace mozilla {
+
+/**
+ * Observer<T> provides a way for a class to observe something.
+ * When an event has to be broadcasted to all Observer<T>, Notify() method
+ * is called.
+ * T represents the type of the object passed in argument to Notify().
+ *
+ * @see ObserverList.
+ */
+template<class T>
+class Observer
+{
+public:
+  virtual ~Observer() {}
+  virtual void Notify(const T& aParam) = 0;
+};
+
+/**
+ * ObserverList<T> tracks Observer<T> and can notify them when Broadcast() is
+ * called.
+ * T represents the type of the object passed in argument to Broadcast() and
+ * sent to Observer<T> objects through Notify().
+ *
+ * @see Observer.
+ */
+template<class T>
+class ObserverList
+{
+public:
+  /**
+   * Note: When calling AddObserver, it's up to the caller to make sure the
+   * object isn't going to be release as long as RemoveObserver hasn't been
+   * called.
+   *
+   * @see RemoveObserver()
+   */
+  void AddObserver(Observer<T>* aObserver)
+  {
+    mObservers.AppendElement(aObserver);
+  }
+
+  /**
+   * Remove the observer from the observer list.
+   * @return Whether the observer has been found in the list.
+   */
+  bool RemoveObserver(Observer<T>* aObserver)
+  {
+    return mObservers.RemoveElement(aObserver);
+  }
+
+  uint32_t Length()
+  {
+    return mObservers.Length();
+  }
+
+  void Broadcast(const T& aParam)
+  {
+    nsTArray<Observer<T>*> observersCopy(mObservers);
+    uint32_t size = observersCopy.Length();
+    for (uint32_t i = 0; i < size; ++i) {
+      observersCopy[i]->Notify(aParam);
+    }
+  }
+
+protected:
+  nsTArray<Observer<T>*> mObservers;
+};
+
+} // namespace mozilla
+
+#endif // mozilla_Observer_h
diff --git a/xpcom/glue/PLDHashTable.cpp b/xpcom/glue/PLDHashTable.cpp
new file mode 100644
index 000000000..6152e9000
--- /dev/null
+++ b/xpcom/glue/PLDHashTable.cpp
@@ -0,0 +1,801 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <new>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "PLDHashTable.h"
+#include "mozilla/HashFunctions.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/OperatorNewExtensions.h"
+#include "nsAlgorithm.h"
+#include "mozilla/Likely.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/ChaosMode.h"
+
+using namespace mozilla;
+
+#ifdef DEBUG
+
+class AutoReadOp
+{
+  Checker& mChk;
+public:
+  explicit AutoReadOp(Checker& aChk) : mChk(aChk) { mChk.StartReadOp(); }
+  ~AutoReadOp() { mChk.EndReadOp(); }
+};
+
+class AutoWriteOp
+{
+  Checker& mChk;
+public:
+  explicit AutoWriteOp(Checker& aChk) : mChk(aChk) { mChk.StartWriteOp(); }
+  ~AutoWriteOp() { mChk.EndWriteOp(); }
+};
+
+class AutoIteratorRemovalOp
+{
+  Checker& mChk;
+public:
+  explicit AutoIteratorRemovalOp(Checker& aChk)
+    : mChk(aChk)
+  {
+    mChk.StartIteratorRemovalOp();
+  }
+  ~AutoIteratorRemovalOp() { mChk.EndIteratorRemovalOp(); }
+};
+
+class AutoDestructorOp
+{
+  Checker& mChk;
+public:
+  explicit AutoDestructorOp(Checker& aChk)
+    : mChk(aChk)
+  {
+    mChk.StartDestructorOp();
+  }
+  ~AutoDestructorOp() { mChk.EndDestructorOp(); }
+};
+
+#endif
+
+/* static */ PLDHashNumber
+PLDHashTable::HashStringKey(const void* aKey)
+{
+  return HashString(static_cast<const char*>(aKey));
+}
+
+/* static */ PLDHashNumber
+PLDHashTable::HashVoidPtrKeyStub(const void* aKey)
+{
+  return (PLDHashNumber)(ptrdiff_t)aKey >> 2;
+}
+
+/* static */ bool
+PLDHashTable::MatchEntryStub(const PLDHashEntryHdr* aEntry, const void* aKey)
+{
+  const PLDHashEntryStub* stub = (const PLDHashEntryStub*)aEntry;
+
+  return stub->key == aKey;
+}
+
+/* static */ bool
+PLDHashTable::MatchStringKey(const PLDHashEntryHdr* aEntry, const void* aKey)
+{
+  const PLDHashEntryStub* stub = (const PLDHashEntryStub*)aEntry;
+
+  // XXX tolerate null keys on account of sloppy Mozilla callers.
+  return stub->key == aKey ||
+         (stub->key && aKey &&
+          strcmp((const char*)stub->key, (const char*)aKey) == 0);
+}
+
+/* static */ void
+PLDHashTable::MoveEntryStub(PLDHashTable* aTable,
+                            const PLDHashEntryHdr* aFrom,
+                            PLDHashEntryHdr* aTo)
+{
+  memcpy(aTo, aFrom, aTable->mEntrySize);
+}
+
+/* static */ void
+PLDHashTable::ClearEntryStub(PLDHashTable* aTable, PLDHashEntryHdr* aEntry)
+{
+  memset(aEntry, 0, aTable->mEntrySize);
+}
+
+static const PLDHashTableOps gStubOps = {
+  PLDHashTable::HashVoidPtrKeyStub,
+  PLDHashTable::MatchEntryStub,
+  PLDHashTable::MoveEntryStub,
+  PLDHashTable::ClearEntryStub,
+  nullptr
+};
+
+/* static */ const PLDHashTableOps*
+PLDHashTable::StubOps()
+{
+  return &gStubOps;
+}
+
+static bool
+SizeOfEntryStore(uint32_t aCapacity, uint32_t aEntrySize, uint32_t* aNbytes)
+{
+  uint64_t nbytes64 = uint64_t(aCapacity) * uint64_t(aEntrySize);
+  *aNbytes = aCapacity * aEntrySize;
+  return uint64_t(*aNbytes) == nbytes64;   // returns false on overflow
+}
+
+// Compute max and min load numbers (entry counts). We have a secondary max
+// that allows us to overload a table reasonably if it cannot be grown further
+// (i.e. if ChangeTable() fails). The table slows down drastically if the
+// secondary max is too close to 1, but 0.96875 gives only a slight slowdown
+// while allowing 1.3x more elements.
+static inline uint32_t
+MaxLoad(uint32_t aCapacity)
+{
+  return aCapacity - (aCapacity >> 2);  // == aCapacity * 0.75
+}
+static inline uint32_t
+MaxLoadOnGrowthFailure(uint32_t aCapacity)
+{
+  return aCapacity - (aCapacity >> 5);  // == aCapacity * 0.96875
+}
+static inline uint32_t
+MinLoad(uint32_t aCapacity)
+{
+  return aCapacity >> 2;                // == aCapacity * 0.25
+}
+
+// Compute the minimum capacity (and the Log2 of that capacity) for a table
+// containing |aLength| elements while respecting the following contraints:
+// - table must be at most 75% full;
+// - capacity must be a power of two;
+// - capacity cannot be too small.
+static inline void
+BestCapacity(uint32_t aLength, uint32_t* aCapacityOut,
+             uint32_t* aLog2CapacityOut)
+{
+  // Compute the smallest capacity allowing |aLength| elements to be inserted
+  // without rehashing.
+  uint32_t capacity = (aLength * 4 + (3 - 1)) / 3; // == ceil(aLength * 4 / 3)
+  if (capacity < PLDHashTable::kMinCapacity) {
+    capacity = PLDHashTable::kMinCapacity;
+  }
+
+  // Round up capacity to next power-of-two.
+  uint32_t log2 = CeilingLog2(capacity);
+  capacity = 1u << log2;
+  MOZ_ASSERT(capacity <= PLDHashTable::kMaxCapacity);
+
+  *aCapacityOut = capacity;
+  *aLog2CapacityOut = log2;
+}
+
+/* static */ MOZ_ALWAYS_INLINE uint32_t
+PLDHashTable::HashShift(uint32_t aEntrySize, uint32_t aLength)
+{
+  if (aLength > kMaxInitialLength) {
+    MOZ_CRASH("Initial length is too large");
+  }
+
+  uint32_t capacity, log2;
+  BestCapacity(aLength, &capacity, &log2);
+
+  uint32_t nbytes;
+  if (!SizeOfEntryStore(capacity, aEntrySize, &nbytes)) {
+    MOZ_CRASH("Initial entry store size is too large");
+  }
+
+  // Compute the hashShift value.
+  return kHashBits - log2;
+}
+
+PLDHashTable::PLDHashTable(const PLDHashTableOps* aOps, uint32_t aEntrySize,
+                           uint32_t aLength)
+  : mOps(aOps)
+  , mHashShift(HashShift(aEntrySize, aLength))
+  , mEntrySize(aEntrySize)
+  , mEntryCount(0)
+  , mRemovedCount(0)
+  , mEntryStore()
+#ifdef DEBUG
+  , mChecker()
+#endif
+{
+}
+
+PLDHashTable&
+PLDHashTable::operator=(PLDHashTable&& aOther)
+{
+  if (this == &aOther) {
+    return *this;
+  }
+
+  // Destruct |this|.
+  this->~PLDHashTable();
+
+  // |mOps| and |mEntrySize| are const so we can't assign them. Instead, we
+  // require that they are equal. The justification for this is that they're
+  // conceptually part of the type -- indeed, if PLDHashTable was a templated
+  // type like nsTHashtable, they *would* be part of the type -- so it only
+  // makes sense to assign in cases where they match.
+  MOZ_RELEASE_ASSERT(mOps == aOther.mOps);
+  MOZ_RELEASE_ASSERT(mEntrySize == aOther.mEntrySize);
+
+  // Move non-const pieces over.
+  mHashShift = Move(aOther.mHashShift);
+  mEntryCount = Move(aOther.mEntryCount);
+  mRemovedCount = Move(aOther.mRemovedCount);
+  mEntryStore = Move(aOther.mEntryStore);
+#ifdef DEBUG
+  mChecker = Move(aOther.mChecker);
+#endif
+
+  // Clear up |aOther| so its destruction will be a no-op.
+  {
+#ifdef DEBUG
+    AutoDestructorOp op(mChecker);
+#endif
+    aOther.mEntryStore.Set(nullptr);
+  }
+
+  return *this;
+}
+
+PLDHashNumber
+PLDHashTable::Hash1(PLDHashNumber aHash0)
+{
+  return aHash0 >> mHashShift;
+}
+
+// Double hashing needs the second hash code to be relatively prime to table
+// size, so we simply make hash2 odd.
+void
+PLDHashTable::Hash2(PLDHashNumber aHash,
+                    uint32_t& aHash2Out, uint32_t& aSizeMaskOut)
+{
+  uint32_t sizeLog2 = kHashBits - mHashShift;
+  aHash2Out = ((aHash << sizeLog2) >> mHashShift) | 1;
+  aSizeMaskOut = (PLDHashNumber(1) << sizeLog2) - 1;
+}
+
+// Reserve mKeyHash 0 for free entries and 1 for removed-entry sentinels. Note
+// that a removed-entry sentinel need be stored only if the removed entry had
+// a colliding entry added after it. Therefore we can use 1 as the collision
+// flag in addition to the removed-entry sentinel value. Multiplicative hash
+// uses the high order bits of mKeyHash, so this least-significant reservation
+// should not hurt the hash function's effectiveness much.
+
+// Match an entry's mKeyHash against an unstored one computed from a key.
+/* static */ bool
+PLDHashTable::MatchEntryKeyhash(PLDHashEntryHdr* aEntry, PLDHashNumber aKeyHash)
+{
+  return (aEntry->mKeyHash & ~kCollisionFlag) == aKeyHash;
+}
+
+// Compute the address of the indexed entry in table.
+PLDHashEntryHdr*
+PLDHashTable::AddressEntry(uint32_t aIndex)
+{
+  return reinterpret_cast<PLDHashEntryHdr*>(
+    mEntryStore.Get() + aIndex * mEntrySize);
+}
+
+PLDHashTable::~PLDHashTable()
+{
+#ifdef DEBUG
+  AutoDestructorOp op(mChecker);
+#endif
+
+  if (!mEntryStore.Get()) {
+    return;
+  }
+
+  // Clear any remaining live entries.
+  char* entryAddr = mEntryStore.Get();
+  char* entryLimit = entryAddr + Capacity() * mEntrySize;
+  while (entryAddr < entryLimit) {
+    PLDHashEntryHdr* entry = (PLDHashEntryHdr*)entryAddr;
+    if (EntryIsLive(entry)) {
+      mOps->clearEntry(this, entry);
+    }
+    entryAddr += mEntrySize;
+  }
+
+  // Entry storage is freed last, by ~EntryStore().
+}
+
+void
+PLDHashTable::ClearAndPrepareForLength(uint32_t aLength)
+{
+  // Get these values before the destructor clobbers them.
+  const PLDHashTableOps* ops = mOps;
+  uint32_t entrySize = mEntrySize;
+
+  this->~PLDHashTable();
+  new (KnownNotNull, this) PLDHashTable(ops, entrySize, aLength);
+}
+
+void
+PLDHashTable::Clear()
+{
+  ClearAndPrepareForLength(kDefaultInitialLength);
+}
+
+// If |Reason| is |ForAdd|, the return value is always non-null and it may be
+// a previously-removed entry. If |Reason| is |ForSearchOrRemove|, the return
+// value is null on a miss, and will never be a previously-removed entry on a
+// hit. This distinction is a bit grotty but this function is hot enough that
+// these differences are worthwhile.
+template <PLDHashTable::SearchReason Reason>
+PLDHashEntryHdr* NS_FASTCALL
+PLDHashTable::SearchTable(const void* aKey, PLDHashNumber aKeyHash)
+{
+  MOZ_ASSERT(mEntryStore.Get());
+  NS_ASSERTION(!(aKeyHash & kCollisionFlag),
+               "!(aKeyHash & kCollisionFlag)");
+
+  // Compute the primary hash address.
+  PLDHashNumber hash1 = Hash1(aKeyHash);
+  PLDHashEntryHdr* entry = AddressEntry(hash1);
+
+  // Miss: return space for a new entry.
+  if (EntryIsFree(entry)) {
+    return (Reason == ForAdd) ? entry : nullptr;
+  }
+
+  // Hit: return entry.
+  PLDHashMatchEntry matchEntry = mOps->matchEntry;
+  if (MatchEntryKeyhash(entry, aKeyHash) &&
+      matchEntry(entry, aKey)) {
+    return entry;
+  }
+
+  // Collision: double hash.
+  PLDHashNumber hash2;
+  uint32_t sizeMask;
+  Hash2(aKeyHash, hash2, sizeMask);
+
+  // Save the first removed entry pointer so Add() can recycle it. (Only used
+  // if Reason==ForAdd.)
+  PLDHashEntryHdr* firstRemoved = nullptr;
+
+  for (;;) {
+    if (Reason == ForAdd) {
+      if (MOZ_UNLIKELY(EntryIsRemoved(entry))) {
+        if (!firstRemoved) {
+          firstRemoved = entry;
+        }
+      } else {
+        entry->mKeyHash |= kCollisionFlag;
+      }
+    }
+
+    hash1 -= hash2;
+    hash1 &= sizeMask;
+
+    entry = AddressEntry(hash1);
+    if (EntryIsFree(entry)) {
+      return (Reason == ForAdd) ? (firstRemoved ? firstRemoved : entry)
+                                : nullptr;
+    }
+
+    if (MatchEntryKeyhash(entry, aKeyHash) &&
+        matchEntry(entry, aKey)) {
+      return entry;
+    }
+  }
+
+  // NOTREACHED
+  return nullptr;
+}
+
+// This is a copy of SearchTable(), used by ChangeTable(), hardcoded to
+//   1. assume |Reason| is |ForAdd|,
+//   2. assume that |aKey| will never match an existing entry, and
+//   3. assume that no entries have been removed from the current table
+//      structure.
+// Avoiding the need for |aKey| means we can avoid needing a way to map entries
+// to keys, which means callers can use complex key types more easily.
+MOZ_ALWAYS_INLINE PLDHashEntryHdr*
+PLDHashTable::FindFreeEntry(PLDHashNumber aKeyHash)
+{
+  MOZ_ASSERT(mEntryStore.Get());
+  NS_ASSERTION(!(aKeyHash & kCollisionFlag),
+               "!(aKeyHash & kCollisionFlag)");
+
+  // Compute the primary hash address.
+  PLDHashNumber hash1 = Hash1(aKeyHash);
+  PLDHashEntryHdr* entry = AddressEntry(hash1);
+
+  // Miss: return space for a new entry.
+  if (EntryIsFree(entry)) {
+    return entry;
+  }
+
+  // Collision: double hash.
+  PLDHashNumber hash2;
+  uint32_t sizeMask;
+  Hash2(aKeyHash, hash2, sizeMask);
+
+  for (;;) {
+    NS_ASSERTION(!EntryIsRemoved(entry),
+                 "!EntryIsRemoved(entry)");
+    entry->mKeyHash |= kCollisionFlag;
+
+    hash1 -= hash2;
+    hash1 &= sizeMask;
+
+    entry = AddressEntry(hash1);
+    if (EntryIsFree(entry)) {
+      return entry;
+    }
+  }
+
+  // NOTREACHED
+}
+
+bool
+PLDHashTable::ChangeTable(int32_t aDeltaLog2)
+{
+  MOZ_ASSERT(mEntryStore.Get());
+
+  // Look, but don't touch, until we succeed in getting new entry store.
+  int32_t oldLog2 = kHashBits - mHashShift;
+  int32_t newLog2 = oldLog2 + aDeltaLog2;
+  uint32_t newCapacity = 1u << newLog2;
+  if (newCapacity > kMaxCapacity) {
+    return false;
+  }
+
+  uint32_t nbytes;
+  if (!SizeOfEntryStore(newCapacity, mEntrySize, &nbytes)) {
+    return false;   // overflowed
+  }
+
+  char* newEntryStore = (char*)malloc(nbytes);
+  if (!newEntryStore) {
+    return false;
+  }
+
+  // We can't fail from here on, so update table parameters.
+  mHashShift = kHashBits - newLog2;
+  mRemovedCount = 0;
+
+  // Assign the new entry store to table.
+  memset(newEntryStore, 0, nbytes);
+  char* oldEntryStore;
+  char* oldEntryAddr;
+  oldEntryAddr = oldEntryStore = mEntryStore.Get();
+  mEntryStore.Set(newEntryStore);
+  PLDHashMoveEntry moveEntry = mOps->moveEntry;
+
+  // Copy only live entries, leaving removed ones behind.
+  uint32_t oldCapacity = 1u << oldLog2;
+  for (uint32_t i = 0; i < oldCapacity; ++i) {
+    PLDHashEntryHdr* oldEntry = (PLDHashEntryHdr*)oldEntryAddr;
+    if (EntryIsLive(oldEntry)) {
+      oldEntry->mKeyHash &= ~kCollisionFlag;
+      PLDHashEntryHdr* newEntry = FindFreeEntry(oldEntry->mKeyHash);
+      NS_ASSERTION(EntryIsFree(newEntry), "EntryIsFree(newEntry)");
+      moveEntry(this, oldEntry, newEntry);
+      newEntry->mKeyHash = oldEntry->mKeyHash;
+    }
+    oldEntryAddr += mEntrySize;
+  }
+
+  free(oldEntryStore);
+  return true;
+}
+
+MOZ_ALWAYS_INLINE PLDHashNumber
+PLDHashTable::ComputeKeyHash(const void* aKey)
+{
+  MOZ_ASSERT(mEntryStore.Get());
+
+  PLDHashNumber keyHash = mOps->hashKey(aKey);
+  keyHash *= kGoldenRatio;
+
+  // Avoid 0 and 1 hash codes, they indicate free and removed entries.
+  if (keyHash < 2) {
+    keyHash -= 2;
+  }
+  keyHash &= ~kCollisionFlag;
+
+  return keyHash;
+}
+
+PLDHashEntryHdr*
+PLDHashTable::Search(const void* aKey)
+{
+#ifdef DEBUG
+  AutoReadOp op(mChecker);
+#endif
+
+  PLDHashEntryHdr* entry = mEntryStore.Get()
+                         ? SearchTable<ForSearchOrRemove>(aKey,
+                                                          ComputeKeyHash(aKey))
+                         : nullptr;
+  return entry;
+}
+
+PLDHashEntryHdr*
+PLDHashTable::Add(const void* aKey, const mozilla::fallible_t&)
+{
+#ifdef DEBUG
+  AutoWriteOp op(mChecker);
+#endif
+
+  // Allocate the entry storage if it hasn't already been allocated.
+  if (!mEntryStore.Get()) {
+    uint32_t nbytes;
+    // We already checked this in the constructor, so it must still be true.
+    MOZ_RELEASE_ASSERT(SizeOfEntryStore(CapacityFromHashShift(), mEntrySize,
+                                        &nbytes));
+    mEntryStore.Set((char*)malloc(nbytes));
+    if (!mEntryStore.Get()) {
+      return nullptr;
+    }
+    memset(mEntryStore.Get(), 0, nbytes);
+  }
+
+  // If alpha is >= .75, grow or compress the table. If aKey is already in the
+  // table, we may grow once more than necessary, but only if we are on the
+  // edge of being overloaded.
+  uint32_t capacity = Capacity();
+  if (mEntryCount + mRemovedCount >= MaxLoad(capacity)) {
+    // Compress if a quarter or more of all entries are removed.
+    int deltaLog2;
+    if (mRemovedCount >= capacity >> 2) {
+      deltaLog2 = 0;
+    } else {
+      deltaLog2 = 1;
+    }
+
+    // Grow or compress the table. If ChangeTable() fails, allow overloading up
+    // to the secondary max. Once we hit the secondary max, return null.
+    if (!ChangeTable(deltaLog2) &&
+        mEntryCount + mRemovedCount >= MaxLoadOnGrowthFailure(capacity)) {
+      return nullptr;
+    }
+  }
+
+  // Look for entry after possibly growing, so we don't have to add it,
+  // then skip it while growing the table and re-add it after.
+  PLDHashNumber keyHash = ComputeKeyHash(aKey);
+  PLDHashEntryHdr* entry = SearchTable<ForAdd>(aKey, keyHash);
+  if (!EntryIsLive(entry)) {
+    // Initialize the entry, indicating that it's no longer free.
+    if (EntryIsRemoved(entry)) {
+      mRemovedCount--;
+      keyHash |= kCollisionFlag;
+    }
+    if (mOps->initEntry) {
+      mOps->initEntry(entry, aKey);
+    }
+    entry->mKeyHash = keyHash;
+    mEntryCount++;
+  }
+
+  return entry;
+}
+
+PLDHashEntryHdr*
+PLDHashTable::Add(const void* aKey)
+{
+  PLDHashEntryHdr* entry = Add(aKey, fallible);
+  if (!entry) {
+    if (!mEntryStore.Get()) {
+      // We OOM'd while allocating the initial entry storage.
+      uint32_t nbytes;
+      (void) SizeOfEntryStore(CapacityFromHashShift(), mEntrySize, &nbytes);
+      NS_ABORT_OOM(nbytes);
+    } else {
+      // We failed to resize the existing entry storage, either due to OOM or
+      // because we exceeded the maximum table capacity or size; report it as
+      // an OOM. The multiplication by 2 gets us the size we tried to allocate,
+      // which is double the current size.
+      NS_ABORT_OOM(2 * EntrySize() * EntryCount());
+    }
+  }
+  return entry;
+}
+
+void
+PLDHashTable::Remove(const void* aKey)
+{
+#ifdef DEBUG
+  AutoWriteOp op(mChecker);
+#endif
+
+  PLDHashEntryHdr* entry = mEntryStore.Get()
+                         ? SearchTable<ForSearchOrRemove>(aKey,
+                                                          ComputeKeyHash(aKey))
+                         : nullptr;
+  if (entry) {
+    RawRemove(entry);
+    ShrinkIfAppropriate();
+  }
+}
+
+void
+PLDHashTable::RemoveEntry(PLDHashEntryHdr* aEntry)
+{
+#ifdef DEBUG
+  AutoWriteOp op(mChecker);
+#endif
+
+  RawRemove(aEntry);
+  ShrinkIfAppropriate();
+}
+
+void
+PLDHashTable::RawRemove(PLDHashEntryHdr* aEntry)
+{
+  // Unfortunately, we can only do weak checking here. That's because
+  // RawRemove() can be called legitimately while an Enumerate() call is
+  // active, which doesn't fit well into how Checker's mState variable works.
+  MOZ_ASSERT(mChecker.IsWritable());
+
+  MOZ_ASSERT(mEntryStore.Get());
+
+  MOZ_ASSERT(EntryIsLive(aEntry), "EntryIsLive(aEntry)");
+
+  // Load keyHash first in case clearEntry() goofs it.
+  PLDHashNumber keyHash = aEntry->mKeyHash;
+  mOps->clearEntry(this, aEntry);
+  if (keyHash & kCollisionFlag) {
+    MarkEntryRemoved(aEntry);
+    mRemovedCount++;
+  } else {
+    MarkEntryFree(aEntry);
+  }
+  mEntryCount--;
+}
+
+// Shrink or compress if a quarter or more of all entries are removed, or if the
+// table is underloaded according to the minimum alpha, and is not minimal-size
+// already.
+void
+PLDHashTable::ShrinkIfAppropriate()
+{
+  uint32_t capacity = Capacity();
+  if (mRemovedCount >= capacity >> 2 ||
+      (capacity > kMinCapacity && mEntryCount <= MinLoad(capacity))) {
+    uint32_t log2;
+    BestCapacity(mEntryCount, &capacity, &log2);
+
+    int32_t deltaLog2 = log2 - (kHashBits - mHashShift);
+    MOZ_ASSERT(deltaLog2 <= 0);
+
+    (void) ChangeTable(deltaLog2);
+  }
+}
+
+size_t
+PLDHashTable::ShallowSizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
+{
+#ifdef DEBUG
+  AutoReadOp op(mChecker);
+#endif
+
+  return aMallocSizeOf(mEntryStore.Get());
+}
+
+size_t
+PLDHashTable::ShallowSizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
+{
+  return aMallocSizeOf(this) + ShallowSizeOfExcludingThis(aMallocSizeOf);
+}
+
+PLDHashTable::Iterator::Iterator(Iterator&& aOther)
+  : mTable(aOther.mTable)
+  , mStart(aOther.mStart)
+  , mLimit(aOther.mLimit)
+  , mCurrent(aOther.mCurrent)
+  , mNexts(aOther.mNexts)
+  , mNextsLimit(aOther.mNextsLimit)
+  , mHaveRemoved(aOther.mHaveRemoved)
+{
+  // No need to change |mChecker| here.
+  aOther.mTable = nullptr;
+  aOther.mStart = nullptr;
+  aOther.mLimit = nullptr;
+  aOther.mCurrent = nullptr;
+  aOther.mNexts = 0;
+  aOther.mNextsLimit = 0;
+  aOther.mHaveRemoved = false;
+}
+
+PLDHashTable::Iterator::Iterator(PLDHashTable* aTable)
+  : mTable(aTable)
+  , mStart(mTable->mEntryStore.Get())
+  , mLimit(mTable->mEntryStore.Get() + mTable->Capacity() * mTable->mEntrySize)
+  , mCurrent(mTable->mEntryStore.Get())
+  , mNexts(0)
+  , mNextsLimit(mTable->EntryCount())
+  , mHaveRemoved(false)
+{
+#ifdef DEBUG
+  mTable->mChecker.StartReadOp();
+#endif
+
+  if (ChaosMode::isActive(ChaosFeature::HashTableIteration) &&
+      mTable->Capacity() > 0) {
+    // Start iterating at a random entry. It would be even more chaotic to
+    // iterate in fully random order, but that's harder.
+    mCurrent += ChaosMode::randomUint32LessThan(mTable->Capacity()) *
+                mTable->mEntrySize;
+  }
+
+  // Advance to the first live entry, if there is one.
+  if (!Done()) {
+    while (IsOnNonLiveEntry()) {
+      MoveToNextEntry();
+    }
+  }
+}
+
+PLDHashTable::Iterator::~Iterator()
+{
+  if (mTable) {
+    if (mHaveRemoved) {
+      mTable->ShrinkIfAppropriate();
+    }
+#ifdef DEBUG
+    mTable->mChecker.EndReadOp();
+#endif
+  }
+}
+
+MOZ_ALWAYS_INLINE bool
+PLDHashTable::Iterator::IsOnNonLiveEntry() const
+{
+  MOZ_ASSERT(!Done());
+  return !EntryIsLive(reinterpret_cast<PLDHashEntryHdr*>(mCurrent));
+}
+
+MOZ_ALWAYS_INLINE void
+PLDHashTable::Iterator::MoveToNextEntry()
+{
+  mCurrent += mTable->mEntrySize;
+  if (mCurrent == mLimit) {
+    mCurrent = mStart;  // Wrap-around. Possible due to Chaos Mode.
+  }
+}
+
+void
+PLDHashTable::Iterator::Next()
+{
+  MOZ_ASSERT(!Done());
+
+  mNexts++;
+
+  // Advance to the next live entry, if there is one.
+  if (!Done()) {
+    do {
+      MoveToNextEntry();
+    } while (IsOnNonLiveEntry());
+  }
+}
+
+void
+PLDHashTable::Iterator::Remove()
+{
+  // This cast is needed for the same reason as the one in the destructor.
+  mTable->RawRemove(Get());
+  mHaveRemoved = true;
+}
+
+#ifdef DEBUG
+void
+PLDHashTable::MarkImmutable()
+{
+  mChecker.SetNonWritable();
+}
+#endif
diff --git a/xpcom/glue/PLDHashTable.h b/xpcom/glue/PLDHashTable.h
new file mode 100644
index 000000000..cd1323dbe
--- /dev/null
+++ b/xpcom/glue/PLDHashTable.h
@@ -0,0 +1,621 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef PLDHashTable_h
+#define PLDHashTable_h
+
+#include "mozilla/Atomics.h"
+#include "mozilla/Attributes.h" // for MOZ_ALWAYS_INLINE
+#include "mozilla/fallible.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Move.h"
+#include "mozilla/Types.h"
+#include "nscore.h"
+
+typedef uint32_t PLDHashNumber;
+
+class PLDHashTable;
+struct PLDHashTableOps;
+
+// Table entry header structure.
+//
+// In order to allow in-line allocation of key and value, we do not declare
+// either here. Instead, the API uses const void *key as a formal parameter.
+// The key need not be stored in the entry; it may be part of the value, but
+// need not be stored at all.
+//
+// Callback types are defined below and grouped into the PLDHashTableOps
+// structure, for single static initialization per hash table sub-type.
+//
+// Each hash table sub-type should make its entry type a subclass of
+// PLDHashEntryHdr. The mKeyHash member contains the result of multiplying the
+// hash code returned from the hashKey callback (see below) by kGoldenRatio,
+// then constraining the result to avoid the magic 0 and 1 values. The stored
+// mKeyHash value is table size invariant, and it is maintained automatically
+// -- users need never access it.
+struct PLDHashEntryHdr
+{
+private:
+  friend class PLDHashTable;
+
+  PLDHashNumber mKeyHash;
+};
+
+#ifdef DEBUG
+
+// This class does three kinds of checking:
+//
+// - that calls to one of |mOps| or to an enumerator do not cause re-entry into
+//   the table in an unsafe way;
+//
+// - that multiple threads do not access the table in an unsafe way;
+//
+// - that a table marked as immutable is not modified.
+//
+// "Safe" here means that multiple concurrent read operations are ok, but a
+// write operation (i.e. one that can cause the entry storage to be reallocated
+// or destroyed) cannot safely run concurrently with another read or write
+// operation. This meaning of "safe" is only partial; for example, it does not
+// cover whether a single entry in the table is modified by two separate
+// threads. (Doing such checking would be much harder.)
+//
+// It does this with two variables:
+//
+// - mState, which embodies a tri-stage tagged union with the following
+//   variants:
+//   - Idle
+//   - Read(n), where 'n' is the number of concurrent read operations
+//   - Write
+//
+// - mIsWritable, which indicates if the table is mutable.
+//
+class Checker
+{
+public:
+  constexpr Checker() : mState(kIdle), mIsWritable(1) {}
+
+  Checker& operator=(Checker&& aOther) {
+    // Atomic<> doesn't have an |operator=(Atomic<>&&)|.
+    mState = uint32_t(aOther.mState);
+    mIsWritable = uint32_t(aOther.mIsWritable);
+
+    aOther.mState = kIdle;
+
+    return *this;
+  }
+
+  static bool IsIdle(uint32_t aState)  { return aState == kIdle; }
+  static bool IsRead(uint32_t aState)  { return kRead1 <= aState &&
+                                                aState <= kReadMax; }
+  static bool IsRead1(uint32_t aState) { return aState == kRead1; }
+  static bool IsWrite(uint32_t aState) { return aState == kWrite; }
+
+  bool IsIdle() const { return mState == kIdle; }
+
+  bool IsWritable() const { return !!mIsWritable; }
+
+  void SetNonWritable() { mIsWritable = 0; }
+
+  // NOTE: the obvious way to implement these functions is to (a) check
+  // |mState| is reasonable, and then (b) update |mState|. But the lack of
+  // atomicity in such an implementation can cause problems if we get unlucky
+  // thread interleaving between (a) and (b).
+  //
+  // So instead for |mState| we are careful to (a) first get |mState|'s old
+  // value and assign it a new value in single atomic operation, and only then
+  // (b) check the old value was reasonable. This ensures we don't have
+  // interleaving problems.
+  //
+  // For |mIsWritable| we don't need to be as careful because it can only in
+  // transition in one direction (from writable to non-writable).
+
+  void StartReadOp()
+  {
+    uint32_t oldState = mState++;     // this is an atomic increment
+    MOZ_ASSERT(IsIdle(oldState) || IsRead(oldState));
+    MOZ_ASSERT(oldState < kReadMax);  // check for overflow
+  }
+
+  void EndReadOp()
+  {
+    uint32_t oldState = mState--;     // this is an atomic decrement
+    MOZ_ASSERT(IsRead(oldState));
+  }
+
+  void StartWriteOp()
+  {
+    MOZ_ASSERT(IsWritable());
+    uint32_t oldState = mState.exchange(kWrite);
+    MOZ_ASSERT(IsIdle(oldState));
+  }
+
+  void EndWriteOp()
+  {
+    // Check again that the table is writable, in case it was marked as
+    // non-writable just after the IsWritable() assertion in StartWriteOp()
+    // occurred.
+    MOZ_ASSERT(IsWritable());
+    uint32_t oldState = mState.exchange(kIdle);
+    MOZ_ASSERT(IsWrite(oldState));
+  }
+
+  void StartIteratorRemovalOp()
+  {
+    // When doing removals at the end of iteration, we go from Read1 state to
+    // Write and then back.
+    MOZ_ASSERT(IsWritable());
+    uint32_t oldState = mState.exchange(kWrite);
+    MOZ_ASSERT(IsRead1(oldState));
+  }
+
+  void EndIteratorRemovalOp()
+  {
+    // Check again that the table is writable, in case it was marked as
+    // non-writable just after the IsWritable() assertion in
+    // StartIteratorRemovalOp() occurred.
+    MOZ_ASSERT(IsWritable());
+    uint32_t oldState = mState.exchange(kRead1);
+    MOZ_ASSERT(IsWrite(oldState));
+  }
+
+  void StartDestructorOp()
+  {
+    // A destructor op is like a write, but the table doesn't need to be
+    // writable.
+    uint32_t oldState = mState.exchange(kWrite);
+    MOZ_ASSERT(IsIdle(oldState));
+  }
+
+  void EndDestructorOp()
+  {
+    uint32_t oldState = mState.exchange(kIdle);
+    MOZ_ASSERT(IsWrite(oldState));
+  }
+
+private:
+  // Things of note about the representation of |mState|.
+  // - The values between kRead1..kReadMax represent valid Read(n) values.
+  // - kIdle and kRead1 are deliberately chosen so that incrementing the -
+  //   former gives the latter.
+  // - 9999 concurrent readers should be enough for anybody.
+  static const uint32_t kIdle    = 0;
+  static const uint32_t kRead1   = 1;
+  static const uint32_t kReadMax = 9999;
+  static const uint32_t kWrite   = 10000;
+
+  mutable mozilla::Atomic<uint32_t> mState;
+  mutable mozilla::Atomic<uint32_t> mIsWritable;
+};
+#endif
+
+// A PLDHashTable may be allocated on the stack or within another structure or
+// class. No entry storage is allocated until the first element is added. This
+// means that empty hash tables are cheap, which is good because they are
+// common.
+//
+// There used to be a long, math-heavy comment here about the merits of
+// double hashing vs. chaining; it was removed in bug 1058335. In short, double
+// hashing is more space-efficient unless the element size gets large (in which
+// case you should keep using double hashing but switch to using pointer
+// elements). Also, with double hashing, you can't safely hold an entry pointer
+// and use it after an add or remove operation, unless you sample Generation()
+// before adding or removing, and compare the sample after, dereferencing the
+// entry pointer only if Generation() has not changed.
+class PLDHashTable
+{
+private:
+  // This class maintains the invariant that every time the entry store is
+  // changed, the generation is updated.
+  class EntryStore
+  {
+  private:
+    char* mEntryStore;
+    uint32_t mGeneration;
+
+  public:
+    EntryStore() : mEntryStore(nullptr), mGeneration(0) {}
+
+    ~EntryStore()
+    {
+      free(mEntryStore);
+      mEntryStore = nullptr;
+      mGeneration++;    // a little paranoid, but why not be extra safe?
+    }
+
+    char* Get() { return mEntryStore; }
+    const char* Get() const { return mEntryStore; }
+
+    void Set(char* aEntryStore)
+    {
+      mEntryStore = aEntryStore;
+      mGeneration++;
+    }
+
+    uint32_t Generation() const { return mGeneration; }
+  };
+
+  const PLDHashTableOps* const mOps;  // Virtual operations; see below.
+  int16_t             mHashShift;     // Multiplicative hash shift.
+  const uint32_t      mEntrySize;     // Number of bytes in an entry.
+  uint32_t            mEntryCount;    // Number of entries in table.
+  uint32_t            mRemovedCount;  // Removed entry sentinels in table.
+  EntryStore          mEntryStore;    // (Lazy) entry storage and generation.
+
+#ifdef DEBUG
+  mutable Checker mChecker;
+#endif
+
+public:
+  // Table capacity limit; do not exceed. The max capacity used to be 1<<23 but
+  // that occasionally that wasn't enough. Making it much bigger than 1<<26
+  // probably isn't worthwhile -- tables that big are kind of ridiculous.
+  // Also, the growth operation will (deliberately) fail if |capacity *
+  // mEntrySize| overflows a uint32_t, and mEntrySize is always at least 8
+  // bytes.
+  static const uint32_t kMaxCapacity = ((uint32_t)1 << 26);
+
+  static const uint32_t kMinCapacity = 8;
+
+  // Making this half of kMaxCapacity ensures it'll fit. Nobody should need an
+  // initial length anywhere nearly this large, anyway.
+  static const uint32_t kMaxInitialLength = kMaxCapacity / 2;
+
+  // This gives a default initial capacity of 8.
+  static const uint32_t kDefaultInitialLength = 4;
+
+  // Initialize the table with |aOps| and |aEntrySize|. The table's initial
+  // capacity is chosen such that |aLength| elements can be inserted without
+  // rehashing; if |aLength| is a power-of-two, this capacity will be
+  // |2*length|. However, because entry storage is allocated lazily, this
+  // initial capacity won't be relevant until the first element is added; prior
+  // to that the capacity will be zero.
+  //
+  // This will crash if |aEntrySize| and/or |aLength| are too large.
+  PLDHashTable(const PLDHashTableOps* aOps, uint32_t aEntrySize,
+               uint32_t aLength = kDefaultInitialLength);
+
+  PLDHashTable(PLDHashTable&& aOther)
+      // These two fields are |const|. Initialize them here because the
+      // move assignment operator cannot modify them.
+    : mOps(aOther.mOps)
+    , mEntrySize(aOther.mEntrySize)
+      // Initialize this field because it is required for a safe call to the
+      // destructor, which the move assignment operator does.
+    , mEntryStore()
+#ifdef DEBUG
+    , mChecker()
+#endif
+  {
+    *this = mozilla::Move(aOther);
+  }
+
+  PLDHashTable& operator=(PLDHashTable&& aOther);
+
+  ~PLDHashTable();
+
+  // This should be used rarely.
+  const PLDHashTableOps* Ops() const { return mOps; }
+
+  // Size in entries (gross, not net of free and removed sentinels) for table.
+  // This can be zero if no elements have been added yet, in which case the
+  // entry storage will not have yet been allocated.
+  uint32_t Capacity() const
+  {
+    return mEntryStore.Get() ? CapacityFromHashShift() : 0;
+  }
+
+  uint32_t EntrySize()  const { return mEntrySize; }
+  uint32_t EntryCount() const { return mEntryCount; }
+  uint32_t Generation() const { return mEntryStore.Generation(); }
+
+  // To search for a |key| in |table|, call:
+  //
+  //   entry = table.Search(key);
+  //
+  // If |entry| is non-null, |key| was found. If |entry| is null, key was not
+  // found.
+  PLDHashEntryHdr* Search(const void* aKey);
+
+  // To add an entry identified by |key| to table, call:
+  //
+  //   entry = table.Add(key, mozilla::fallible);
+  //
+  // If |entry| is null upon return, then the table is severely overloaded and
+  // memory can't be allocated for entry storage.
+  //
+  // Otherwise, |aEntry->mKeyHash| has been set so that
+  // PLDHashTable::EntryIsFree(entry) is false, and it is up to the caller to
+  // initialize the key and value parts of the entry sub-type, if they have not
+  // been set already (i.e. if entry was not already in the table, and if the
+  // optional initEntry hook was not used).
+  PLDHashEntryHdr* Add(const void* aKey, const mozilla::fallible_t&);
+
+  // This is like the other Add() function, but infallible, and so never
+  // returns null.
+  PLDHashEntryHdr* Add(const void* aKey);
+
+  // To remove an entry identified by |key| from table, call:
+  //
+  //   table.Remove(key);
+  //
+  // If |key|'s entry is found, it is cleared (via table->mOps->clearEntry).
+  // The table's capacity may be reduced afterwards.
+  void Remove(const void* aKey);
+
+  // To remove an entry found by a prior search, call:
+  //
+  //   table.RemoveEntry(entry);
+  //
+  // The entry, which must be present and in use, is cleared (via
+  // table->mOps->clearEntry). The table's capacity may be reduced afterwards.
+  void RemoveEntry(PLDHashEntryHdr* aEntry);
+
+  // Remove an entry already accessed via Search() or Add().
+  //
+  // NB: this is a "raw" or low-level method. It does not shrink the table if
+  // it is underloaded. Don't use it unless necessary and you know what you are
+  // doing, and if so, please explain in a comment why it is necessary instead
+  // of RemoveEntry().
+  void RawRemove(PLDHashEntryHdr* aEntry);
+
+  // This function is equivalent to
+  // ClearAndPrepareForLength(kDefaultInitialLength).
+  void Clear();
+
+  // This function clears the table's contents and frees its entry storage,
+  // leaving it in a empty state ready to be used again. Afterwards, when the
+  // first element is added the entry storage that gets allocated will have a
+  // capacity large enough to fit |aLength| elements without rehashing.
+  //
+  // It's conceptually the same as calling the destructor and then re-calling
+  // the constructor with the original |aOps| and |aEntrySize| arguments, and
+  // a new |aLength| argument.
+  void ClearAndPrepareForLength(uint32_t aLength);
+
+  // Measure the size of the table's entry storage. If the entries contain
+  // pointers to other heap blocks, you have to iterate over the table and
+  // measure those separately; hence the "Shallow" prefix.
+  size_t ShallowSizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
+
+  // Like ShallowSizeOfExcludingThis(), but includes sizeof(*this).
+  size_t ShallowSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
+
+#ifdef DEBUG
+  // Mark a table as immutable for the remainder of its lifetime. This
+  // changes the implementation from asserting one set of invariants to
+  // asserting a different set.
+  void MarkImmutable();
+#endif
+
+  // If you use PLDHashEntryStub or a subclass of it as your entry struct, and
+  // if your entries move via memcpy and clear via memset(0), you can use these
+  // stub operations.
+  static const PLDHashTableOps* StubOps();
+
+  // The individual stub operations in StubOps().
+  static PLDHashNumber HashVoidPtrKeyStub(const void* aKey);
+  static bool MatchEntryStub(const PLDHashEntryHdr* aEntry, const void* aKey);
+  static void MoveEntryStub(PLDHashTable* aTable, const PLDHashEntryHdr* aFrom,
+                            PLDHashEntryHdr* aTo);
+  static void ClearEntryStub(PLDHashTable* aTable, PLDHashEntryHdr* aEntry);
+
+  // Hash/match operations for tables holding C strings.
+  static PLDHashNumber HashStringKey(const void* aKey);
+  static bool MatchStringKey(const PLDHashEntryHdr* aEntry, const void* aKey);
+
+  // This is an iterator for PLDHashtable. Assertions will detect some, but not
+  // all, mid-iteration table modifications that might invalidate (e.g.
+  // reallocate) the entry storage.
+  //
+  // Any element can be removed during iteration using Remove(). If any
+  // elements are removed, the table may be resized once iteration ends.
+  //
+  // Example usage:
+  //
+  //   for (auto iter = table.Iter(); !iter.Done(); iter.Next()) {
+  //     auto entry = static_cast<FooEntry*>(iter.Get());
+  //     // ... do stuff with |entry| ...
+  //     // ... possibly call iter.Remove() once ...
+  //   }
+  //
+  // or:
+  //
+  //   for (PLDHashTable::Iterator iter(&table); !iter.Done(); iter.Next()) {
+  //     auto entry = static_cast<FooEntry*>(iter.Get());
+  //     // ... do stuff with |entry| ...
+  //     // ... possibly call iter.Remove() once ...
+  //   }
+  //
+  // The latter form is more verbose but is easier to work with when
+  // making subclasses of Iterator.
+  //
+  class Iterator
+  {
+  public:
+    explicit Iterator(PLDHashTable* aTable);
+    Iterator(Iterator&& aOther);
+    ~Iterator();
+
+    // Have we finished?
+    bool Done() const { return mNexts == mNextsLimit; }
+
+    // Get the current entry.
+    PLDHashEntryHdr* Get() const
+    {
+      MOZ_ASSERT(!Done());
+
+      PLDHashEntryHdr* entry = reinterpret_cast<PLDHashEntryHdr*>(mCurrent);
+      MOZ_ASSERT(EntryIsLive(entry));
+      return entry;
+    }
+
+    // Advance to the next entry.
+    void Next();
+
+    // Remove the current entry. Must only be called once per entry, and Get()
+    // must not be called on that entry afterwards.
+    void Remove();
+
+  protected:
+    PLDHashTable* mTable;             // Main table pointer.
+
+  private:
+    char* mStart;                     // The first entry.
+    char* mLimit;                     // One past the last entry.
+    char* mCurrent;                   // Pointer to the current entry.
+    uint32_t mNexts;                  // Number of Next() calls.
+    uint32_t mNextsLimit;             // Next() call limit.
+
+    bool mHaveRemoved;                // Have any elements been removed?
+
+    bool IsOnNonLiveEntry() const;
+    void MoveToNextEntry();
+
+    Iterator() = delete;
+    Iterator(const Iterator&) = delete;
+    Iterator& operator=(const Iterator&) = delete;
+    Iterator& operator=(const Iterator&&) = delete;
+  };
+
+  Iterator Iter() { return Iterator(this); }
+
+  // Use this if you need to initialize an Iterator in a const method. If you
+  // use this case, you should not call Remove() on the iterator.
+  Iterator ConstIter() const
+  {
+    return Iterator(const_cast<PLDHashTable*>(this));
+  }
+
+private:
+  // Multiplicative hash uses an unsigned 32 bit integer and the golden ratio,
+  // expressed as a fixed-point 32-bit fraction.
+  static const uint32_t kHashBits = 32;
+  static const uint32_t kGoldenRatio = 0x9E3779B9U;
+
+  static uint32_t HashShift(uint32_t aEntrySize, uint32_t aLength);
+
+  static const PLDHashNumber kCollisionFlag = 1;
+
+  static bool EntryIsFree(PLDHashEntryHdr* aEntry)
+  {
+    return aEntry->mKeyHash == 0;
+  }
+  static bool EntryIsRemoved(PLDHashEntryHdr* aEntry)
+  {
+    return aEntry->mKeyHash == 1;
+  }
+  static bool EntryIsLive(PLDHashEntryHdr* aEntry)
+  {
+    return aEntry->mKeyHash >= 2;
+  }
+
+  static void MarkEntryFree(PLDHashEntryHdr* aEntry)
+  {
+    aEntry->mKeyHash = 0;
+  }
+  static void MarkEntryRemoved(PLDHashEntryHdr* aEntry)
+  {
+    aEntry->mKeyHash = 1;
+  }
+
+  PLDHashNumber Hash1(PLDHashNumber aHash0);
+  void Hash2(PLDHashNumber aHash, uint32_t& aHash2Out, uint32_t& aSizeMaskOut);
+
+  static bool MatchEntryKeyhash(PLDHashEntryHdr* aEntry, PLDHashNumber aHash);
+  PLDHashEntryHdr* AddressEntry(uint32_t aIndex);
+
+  // We store mHashShift rather than sizeLog2 to optimize the collision-free
+  // case in SearchTable.
+  uint32_t CapacityFromHashShift() const
+  {
+    return ((uint32_t)1 << (kHashBits - mHashShift));
+  }
+
+  PLDHashNumber ComputeKeyHash(const void* aKey);
+
+  enum SearchReason { ForSearchOrRemove, ForAdd };
+
+  template <SearchReason Reason>
+  PLDHashEntryHdr* NS_FASTCALL
+    SearchTable(const void* aKey, PLDHashNumber aKeyHash);
+
+  PLDHashEntryHdr* FindFreeEntry(PLDHashNumber aKeyHash);
+
+  bool ChangeTable(int aDeltaLog2);
+
+  void ShrinkIfAppropriate();
+
+  PLDHashTable(const PLDHashTable& aOther) = delete;
+  PLDHashTable& operator=(const PLDHashTable& aOther) = delete;
+};
+
+// Compute the hash code for a given key to be looked up, added, or removed.
+// A hash code may have any PLDHashNumber value.
+typedef PLDHashNumber (*PLDHashHashKey)(const void* aKey);
+
+// Compare the key identifying aEntry with the provided key parameter. Return
+// true if keys match, false otherwise.
+typedef bool (*PLDHashMatchEntry)(const PLDHashEntryHdr* aEntry,
+                                  const void* aKey);
+
+// Copy the data starting at aFrom to the new entry storage at aTo. Do not add
+// reference counts for any strong references in the entry, however, as this
+// is a "move" operation: the old entry storage at from will be freed without
+// any reference-decrementing callback shortly.
+typedef void (*PLDHashMoveEntry)(PLDHashTable* aTable,
+                                 const PLDHashEntryHdr* aFrom,
+                                 PLDHashEntryHdr* aTo);
+
+// Clear the entry and drop any strong references it holds. This callback is
+// invoked by Remove(), but only if the given key is found in the table.
+typedef void (*PLDHashClearEntry)(PLDHashTable* aTable,
+                                  PLDHashEntryHdr* aEntry);
+
+// Initialize a new entry, apart from mKeyHash. This function is called when
+// Add() finds no existing entry for the given key, and must add a new one. At
+// that point, |aEntry->mKeyHash| is not set yet, to avoid claiming the last
+// free entry in a severely overloaded table.
+typedef void (*PLDHashInitEntry)(PLDHashEntryHdr* aEntry, const void* aKey);
+
+// Finally, the "vtable" structure for PLDHashTable. The first four hooks
+// must be provided by implementations; they're called unconditionally by the
+// generic PLDHashTable.cpp code. Hooks after these may be null.
+//
+// Summary of allocation-related hook usage with C++ placement new emphasis:
+//  initEntry           Call placement new using default key-based ctor.
+//  moveEntry           Call placement new using copy ctor, run dtor on old
+//                      entry storage.
+//  clearEntry          Run dtor on entry.
+//
+// Note the reason why initEntry is optional: the default hooks (stubs) clear
+// entry storage:  On successful Add(tbl, key), the returned entry pointer
+// addresses an entry struct whose mKeyHash member has been set non-zero, but
+// all other entry members are still clear (null). Add() callers can test such
+// members to see whether the entry was newly created by the Add() call that
+// just succeeded. If placement new or similar initialization is required,
+// define an |initEntry| hook. Of course, the |clearEntry| hook must zero or
+// null appropriately.
+//
+// XXX assumes 0 is null for pointer types.
+struct PLDHashTableOps
+{
+  // Mandatory hooks. All implementations must provide these.
+  PLDHashHashKey      hashKey;
+  PLDHashMatchEntry   matchEntry;
+  PLDHashMoveEntry    moveEntry;
+  PLDHashClearEntry   clearEntry;
+
+  // Optional hooks start here. If null, these are not called.
+  PLDHashInitEntry    initEntry;
+};
+
+// A minimal entry is a subclass of PLDHashEntryHdr and has a void* key pointer.
+struct PLDHashEntryStub : public PLDHashEntryHdr
+{
+  const void* key;
+};
+
+#endif /* PLDHashTable_h */
diff --git a/xpcom/glue/ReentrantMonitor.h b/xpcom/glue/ReentrantMonitor.h
new file mode 100644
index 000000000..0798fe2af
--- /dev/null
+++ b/xpcom/glue/ReentrantMonitor.h
@@ -0,0 +1,249 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_ReentrantMonitor_h
+#define mozilla_ReentrantMonitor_h
+
+#include "prmon.h"
+
+#ifdef MOZILLA_INTERNAL_API
+#include "GeckoProfiler.h"
+#endif //MOZILLA_INTERNAL_API
+
+#include "mozilla/BlockingResourceBase.h"
+
+//
+// Provides:
+//
+//  - ReentrantMonitor, a Java-like monitor
+//  - ReentrantMonitorAutoEnter, an RAII class for ensuring that
+//    ReentrantMonitors are properly entered and exited
+//
+// Using ReentrantMonitorAutoEnter is MUCH preferred to making bare calls to
+// ReentrantMonitor.Enter and Exit.
+//
+namespace mozilla {
+
+
+/**
+ * ReentrantMonitor
+ * Java-like monitor.
+ * When possible, use ReentrantMonitorAutoEnter to hold this monitor within a
+ * scope, instead of calling Enter/Exit directly.
+ **/
+class ReentrantMonitor : BlockingResourceBase
+{
+public:
+  /**
+   * ReentrantMonitor
+   * @param aName A name which can reference this monitor
+   */
+  explicit ReentrantMonitor(const char* aName)
+    : BlockingResourceBase(aName, eReentrantMonitor)
+#ifdef DEBUG
+    , mEntryCount(0)
+#endif
+  {
+    MOZ_COUNT_CTOR(ReentrantMonitor);
+    mReentrantMonitor = PR_NewMonitor();
+    if (!mReentrantMonitor) {
+      NS_RUNTIMEABORT("Can't allocate mozilla::ReentrantMonitor");
+    }
+  }
+
+  /**
+   * ~ReentrantMonitor
+   **/
+  ~ReentrantMonitor()
+  {
+    NS_ASSERTION(mReentrantMonitor,
+                 "improperly constructed ReentrantMonitor or double free");
+    PR_DestroyMonitor(mReentrantMonitor);
+    mReentrantMonitor = 0;
+    MOZ_COUNT_DTOR(ReentrantMonitor);
+  }
+
+#ifndef DEBUG
+  /**
+   * Enter
+   * @see prmon.h
+   **/
+  void Enter() { PR_EnterMonitor(mReentrantMonitor); }
+
+  /**
+   * Exit
+   * @see prmon.h
+   **/
+  void Exit() { PR_ExitMonitor(mReentrantMonitor); }
+
+  /**
+   * Wait
+   * @see prmon.h
+   **/
+  nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT)
+  {
+#ifdef MOZILLA_INTERNAL_API
+    GeckoProfilerSleepRAII profiler_sleep;
+#endif //MOZILLA_INTERNAL_API
+    return PR_Wait(mReentrantMonitor, aInterval) == PR_SUCCESS ?
+      NS_OK : NS_ERROR_FAILURE;
+  }
+
+#else // ifndef DEBUG
+  void Enter();
+  void Exit();
+  nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT);
+
+#endif  // ifndef DEBUG
+
+  /**
+   * Notify
+   * @see prmon.h
+   **/
+  nsresult Notify()
+  {
+    return PR_Notify(mReentrantMonitor) == PR_SUCCESS ? NS_OK :
+                                                        NS_ERROR_FAILURE;
+  }
+
+  /**
+   * NotifyAll
+   * @see prmon.h
+   **/
+  nsresult NotifyAll()
+  {
+    return PR_NotifyAll(mReentrantMonitor) == PR_SUCCESS ? NS_OK :
+                                                           NS_ERROR_FAILURE;
+  }
+
+#ifdef DEBUG
+  /**
+   * AssertCurrentThreadIn
+   * @see prmon.h
+   **/
+  void AssertCurrentThreadIn()
+  {
+    PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mReentrantMonitor);
+  }
+
+  /**
+   * AssertNotCurrentThreadIn
+   * @see prmon.h
+   **/
+  void AssertNotCurrentThreadIn()
+  {
+    // FIXME bug 476536
+  }
+
+#else
+  void AssertCurrentThreadIn() {}
+  void AssertNotCurrentThreadIn() {}
+
+#endif  // ifdef DEBUG
+
+private:
+  ReentrantMonitor();
+  ReentrantMonitor(const ReentrantMonitor&);
+  ReentrantMonitor& operator=(const ReentrantMonitor&);
+
+  PRMonitor* mReentrantMonitor;
+#ifdef DEBUG
+  int32_t mEntryCount;
+#endif
+};
+
+
+/**
+ * ReentrantMonitorAutoEnter
+ * Enters the ReentrantMonitor when it enters scope, and exits it when
+ * it leaves scope.
+ *
+ * MUCH PREFERRED to bare calls to ReentrantMonitor.Enter and Exit.
+ */
+class MOZ_STACK_CLASS ReentrantMonitorAutoEnter
+{
+public:
+  /**
+   * Constructor
+   * The constructor aquires the given lock.  The destructor
+   * releases the lock.
+   *
+   * @param aReentrantMonitor A valid mozilla::ReentrantMonitor*.
+   **/
+  explicit ReentrantMonitorAutoEnter(mozilla::ReentrantMonitor& aReentrantMonitor)
+    : mReentrantMonitor(&aReentrantMonitor)
+  {
+    NS_ASSERTION(mReentrantMonitor, "null monitor");
+    mReentrantMonitor->Enter();
+  }
+
+  ~ReentrantMonitorAutoEnter(void)
+  {
+    mReentrantMonitor->Exit();
+  }
+
+  nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT)
+  {
+    return mReentrantMonitor->Wait(aInterval);
+  }
+
+  nsresult Notify() { return mReentrantMonitor->Notify(); }
+  nsresult NotifyAll() { return mReentrantMonitor->NotifyAll(); }
+
+private:
+  ReentrantMonitorAutoEnter();
+  ReentrantMonitorAutoEnter(const ReentrantMonitorAutoEnter&);
+  ReentrantMonitorAutoEnter& operator=(const ReentrantMonitorAutoEnter&);
+  static void* operator new(size_t) CPP_THROW_NEW;
+
+  mozilla::ReentrantMonitor* mReentrantMonitor;
+};
+
+/**
+ * ReentrantMonitorAutoExit
+ * Exit the ReentrantMonitor when it enters scope, and enters it when it leaves
+ * scope.
+ *
+ * MUCH PREFERRED to bare calls to ReentrantMonitor.Exit and Enter.
+ */
+class MOZ_STACK_CLASS ReentrantMonitorAutoExit
+{
+public:
+  /**
+   * Constructor
+   * The constructor releases the given lock.  The destructor
+   * acquires the lock. The lock must be held before constructing
+   * this object!
+   *
+   * @param aReentrantMonitor A valid mozilla::ReentrantMonitor*. It
+   *                 must be already locked.
+   **/
+  explicit ReentrantMonitorAutoExit(ReentrantMonitor& aReentrantMonitor)
+    : mReentrantMonitor(&aReentrantMonitor)
+  {
+    NS_ASSERTION(mReentrantMonitor, "null monitor");
+    mReentrantMonitor->AssertCurrentThreadIn();
+    mReentrantMonitor->Exit();
+  }
+
+  ~ReentrantMonitorAutoExit(void)
+  {
+    mReentrantMonitor->Enter();
+  }
+
+private:
+  ReentrantMonitorAutoExit();
+  ReentrantMonitorAutoExit(const ReentrantMonitorAutoExit&);
+  ReentrantMonitorAutoExit& operator=(const ReentrantMonitorAutoExit&);
+  static void* operator new(size_t) CPP_THROW_NEW;
+
+  ReentrantMonitor* mReentrantMonitor;
+};
+
+} // namespace mozilla
+
+
+#endif // ifndef mozilla_ReentrantMonitor_h
diff --git a/xpcom/glue/moz.build b/xpcom/glue/moz.build
new file mode 100644
index 000000000..95c18b273
--- /dev/null
+++ b/xpcom/glue/moz.build
@@ -0,0 +1,123 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+with Files('nsString*'):
+    BUG_COMPONENT = ('Core', 'String')
+
+DIRS += ['standalone']
+
+# On win we build two glue libs - glue linked to crt dlls here and in staticruntime we build
+# a statically linked glue lib.
+if CONFIG['OS_ARCH'] == 'WINNT':
+    DIRS += ['staticruntime']
+
+EXPORTS += [
+    'MainThreadUtils.h',
+    'nsArrayEnumerator.h',
+    'nsArrayUtils.h',
+    'nsBaseHashtable.h',
+    'nsCategoryCache.h',
+    'nsClassHashtable.h',
+    'nsCOMArray.h',
+    'nsComponentManagerUtils.h',
+    'nsCOMPtr.h',
+    'nsCRTGlue.h',
+    'nsCycleCollectionNoteChild.h',
+    'nsCycleCollectionNoteRootCallback.h',
+    'nsCycleCollectionParticipant.h',
+    'nsCycleCollectionTraversalCallback.h',
+    'nsDataHashtable.h',
+    'nsDebug.h',
+    'nsDeque.h',
+    'nsEnumeratorUtils.h',
+    'nsHashKeys.h',
+    'nsIClassInfoImpl.h',
+    'nsID.h',
+    'nsIInterfaceRequestorUtils.h',
+    'nsINIParser.h',
+    'nsInterfaceHashtable.h',
+    'nsISupportsImpl.h',
+    'nsISupportsUtils.h',
+    'nsIWeakReferenceUtils.h',
+    'nsJSThingHashtable.h',
+    'nsMemory.h',
+    'nsPointerHashKeys.h',
+    'nsProxyRelease.h',
+    'nsQuickSort.h',
+    'nsRefPtrHashtable.h',
+    'nsServiceManagerUtils.h',
+    'nsStringAPI.h',
+    'nsStringGlue.h',
+    'nsTArray-inl.h',
+    'nsTArray.h',
+    'nsTArrayForwardDeclare.h',
+    'nsTextFormatter.h',
+    'nsTHashtable.h',
+    'nsThreadUtils.h',
+    'nsTObserverArray.h',
+    'nsTPriorityQueue.h',
+    'nsTWeakRef.h',
+    'nsVersionComparator.h',
+    'nsWeakReference.h',
+    'nsXPTCUtils.h',
+    'PLDHashTable.h',
+]
+
+EXPORTS.mozilla += [
+    'AppData.h',
+    'AutoRestore.h',
+    'BlockingResourceBase.h',
+    'CondVar.h',
+    'DeadlockDetector.h',
+    'EnumeratedArrayCycleCollection.h',
+    'FileUtils.h',
+    'GenericFactory.h',
+    'IntentionalCrash.h',
+    'Monitor.h',
+    'Mutex.h',
+    'Observer.h',
+    'ReentrantMonitor.h',
+]
+
+include('objs.mozbuild')
+
+UNIFIED_SOURCES += xpcom_gluens_src_cppsrcs
+UNIFIED_SOURCES += xpcom_glue_src_cppsrcs
+
+UNIFIED_SOURCES += [
+    'GenericModule.cpp',
+    'nsStringAPI.cpp',
+]
+
+Library('xpcomglue_s')
+
+SDK_LIBRARY = True
+
+FORCE_STATIC_LIB = True
+
+if CONFIG['_MSC_VER']:
+    DEFINES['_USE_ANSI_CPP'] = True
+    # Don't include directives about which CRT to use
+    CFLAGS += ['-Zl']
+    CXXFLAGS += ['-Zl']
+
+LOCAL_INCLUDES += [
+    '../build',
+    '../threads',
+]
+
+if CONFIG['ENABLE_TESTS']:
+    DIRS += ['tests/gtest']
+
+# Include fallible for third party code using the xpcom glue
+USE_LIBS += [
+    'fallible',
+]
+
+# Force to build a static library only
+NO_EXPAND_LIBS = True
+
+DIST_INSTALL = True
diff --git a/xpcom/glue/nsArrayEnumerator.cpp b/xpcom/glue/nsArrayEnumerator.cpp
new file mode 100644
index 000000000..2d2ef6da7
--- /dev/null
+++ b/xpcom/glue/nsArrayEnumerator.cpp
@@ -0,0 +1,213 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Attributes.h"
+
+#include "nsArrayEnumerator.h"
+
+#include "nsIArray.h"
+#include "nsISimpleEnumerator.h"
+
+#include "nsCOMArray.h"
+#include "nsCOMPtr.h"
+#include "mozilla/RefPtr.h"
+
+class nsSimpleArrayEnumerator final : public nsISimpleEnumerator
+{
+public:
+  // nsISupports interface
+  NS_DECL_ISUPPORTS
+
+  // nsISimpleEnumerator interface
+  NS_DECL_NSISIMPLEENUMERATOR
+
+  // nsSimpleArrayEnumerator methods
+  explicit nsSimpleArrayEnumerator(nsIArray* aValueArray)
+    : mValueArray(aValueArray)
+    , mIndex(0)
+  {
+  }
+
+private:
+  ~nsSimpleArrayEnumerator() {}
+
+protected:
+  nsCOMPtr<nsIArray> mValueArray;
+  uint32_t mIndex;
+};
+
+NS_IMPL_ISUPPORTS(nsSimpleArrayEnumerator, nsISimpleEnumerator)
+
+NS_IMETHODIMP
+nsSimpleArrayEnumerator::HasMoreElements(bool* aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  if (!mValueArray) {
+    *aResult = false;
+    return NS_OK;
+  }
+
+  uint32_t cnt;
+  nsresult rv = mValueArray->GetLength(&cnt);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  *aResult = (mIndex < cnt);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSimpleArrayEnumerator::GetNext(nsISupports** aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  if (!mValueArray) {
+    *aResult = nullptr;
+    return NS_OK;
+  }
+
+  uint32_t cnt;
+  nsresult rv = mValueArray->GetLength(&cnt);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (mIndex >= cnt) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  return mValueArray->QueryElementAt(mIndex++, NS_GET_IID(nsISupports),
+                                     (void**)aResult);
+}
+
+nsresult
+NS_NewArrayEnumerator(nsISimpleEnumerator** aResult, nsIArray* aArray)
+{
+  RefPtr<nsSimpleArrayEnumerator> enumer = new nsSimpleArrayEnumerator(aArray);
+  enumer.forget(aResult);
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+// enumerator implementation for nsCOMArray
+// creates a snapshot of the array in question
+// you MUST use NS_NewArrayEnumerator to create this, so that
+// allocation is done correctly
+class nsCOMArrayEnumerator final : public nsISimpleEnumerator
+{
+public:
+  // nsISupports interface
+  NS_DECL_ISUPPORTS
+
+  // nsISimpleEnumerator interface
+  NS_DECL_NSISIMPLEENUMERATOR
+
+  // nsSimpleArrayEnumerator methods
+  nsCOMArrayEnumerator() : mIndex(0) {}
+
+  // specialized operator to make sure we make room for mValues
+  void* operator new(size_t aSize, const nsCOMArray_base& aArray) CPP_THROW_NEW;
+  void operator delete(void* aPtr) { ::operator delete(aPtr); }
+
+private:
+  ~nsCOMArrayEnumerator(void);
+
+protected:
+  uint32_t mIndex;            // current position
+  uint32_t mArraySize;        // size of the array
+
+  // this is actually bigger
+  nsISupports* mValueArray[1];
+};
+
+NS_IMPL_ISUPPORTS(nsCOMArrayEnumerator, nsISimpleEnumerator)
+
+nsCOMArrayEnumerator::~nsCOMArrayEnumerator()
+{
+  // only release the entries that we haven't visited yet
+  for (; mIndex < mArraySize; ++mIndex) {
+    NS_IF_RELEASE(mValueArray[mIndex]);
+  }
+}
+
+NS_IMETHODIMP
+nsCOMArrayEnumerator::HasMoreElements(bool* aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  *aResult = (mIndex < mArraySize);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsCOMArrayEnumerator::GetNext(nsISupports** aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  if (mIndex >= mArraySize) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  // pass the ownership of the reference to the caller. Since
+  // we AddRef'ed during creation of |this|, there is no need
+  // to AddRef here
+  *aResult = mValueArray[mIndex++];
+
+  // this really isn't necessary. just pretend this happens, since
+  // we'll never visit this value again!
+  // mValueArray[(mIndex-1)] = nullptr;
+
+  return NS_OK;
+}
+
+void*
+nsCOMArrayEnumerator::operator new(size_t aSize,
+                                   const nsCOMArray_base& aArray) CPP_THROW_NEW
+{
+  // create enough space such that mValueArray points to a large
+  // enough value. Note that the initial value of aSize gives us
+  // space for mValueArray[0], so we must subtract
+  aSize += (aArray.Count() - 1) * sizeof(aArray[0]);
+
+  // do the actual allocation
+  nsCOMArrayEnumerator* result =
+    static_cast<nsCOMArrayEnumerator*>(::operator new(aSize));
+
+  // now need to copy over the values, and addref each one
+  // now this might seem like a lot of work, but we're actually just
+  // doing all our AddRef's ahead of time since GetNext() doesn't
+  // need to AddRef() on the way out
+  uint32_t i;
+  uint32_t max = result->mArraySize = aArray.Count();
+  for (i = 0; i < max; ++i) {
+    result->mValueArray[i] = aArray[i];
+    NS_IF_ADDREF(result->mValueArray[i]);
+  }
+
+  return result;
+}
+
+nsresult
+NS_NewArrayEnumerator(nsISimpleEnumerator** aResult,
+                      const nsCOMArray_base& aArray)
+{
+  RefPtr<nsCOMArrayEnumerator> enumerator = new (aArray) nsCOMArrayEnumerator();
+  enumerator.forget(aResult);
+  return NS_OK;
+}
diff --git a/xpcom/glue/nsArrayEnumerator.h b/xpcom/glue/nsArrayEnumerator.h
new file mode 100644
index 000000000..341ae86ed
--- /dev/null
+++ b/xpcom/glue/nsArrayEnumerator.h
@@ -0,0 +1,32 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsArrayEnumerator_h__
+#define nsArrayEnumerator_h__
+
+// enumerator implementation for nsIArray
+
+#include "nscore.h"
+
+class nsISimpleEnumerator;
+class nsIArray;
+class nsCOMArray_base;
+
+// Create an enumerator for an existing nsIArray implementation
+// The enumerator holds an owning reference to the array.
+nsresult
+NS_NewArrayEnumerator(nsISimpleEnumerator** aResult,
+                      nsIArray* aArray);
+
+// create an enumerator for an existing nsCOMArray<T> implementation
+// The enumerator will hold an owning reference to each ELEMENT in
+// the array. This means that the nsCOMArray<T> can safely go away
+// without its objects going away.
+nsresult
+NS_NewArrayEnumerator(nsISimpleEnumerator** aResult,
+                      const nsCOMArray_base& aArray);
+
+#endif
diff --git a/xpcom/glue/nsArrayUtils.cpp b/xpcom/glue/nsArrayUtils.cpp
new file mode 100644
index 000000000..480863737
--- /dev/null
+++ b/xpcom/glue/nsArrayUtils.cpp
@@ -0,0 +1,23 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsArrayUtils.h"
+
+//
+// do_QueryElementAt helper stuff
+//
+nsresult
+nsQueryArrayElementAt::operator()(const nsIID& aIID, void** aResult) const
+{
+  nsresult status = mArray ? mArray->QueryElementAt(mIndex, aIID, aResult) :
+                             NS_ERROR_NULL_POINTER;
+
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+
+  return status;
+}
diff --git a/xpcom/glue/nsArrayUtils.h b/xpcom/glue/nsArrayUtils.h
new file mode 100644
index 000000000..68032e8c0
--- /dev/null
+++ b/xpcom/glue/nsArrayUtils.h
@@ -0,0 +1,40 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsArrayUtils_h__
+#define nsArrayUtils_h__
+
+#include "nsCOMPtr.h"
+#include "nsIArray.h"
+
+// helper class for do_QueryElementAt
+class MOZ_STACK_CLASS nsQueryArrayElementAt final : public nsCOMPtr_helper
+{
+public:
+  nsQueryArrayElementAt(nsIArray* aArray, uint32_t aIndex,
+                        nsresult* aErrorPtr)
+    : mArray(aArray)
+    , mIndex(aIndex)
+    , mErrorPtr(aErrorPtr)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID& aIID, void**) const
+    override;
+
+private:
+  nsIArray* MOZ_NON_OWNING_REF mArray;
+  uint32_t   mIndex;
+  nsresult*  mErrorPtr;
+};
+
+inline const nsQueryArrayElementAt
+do_QueryElementAt(nsIArray* aArray, uint32_t aIndex, nsresult* aErrorPtr = 0)
+{
+  return nsQueryArrayElementAt(aArray, aIndex, aErrorPtr);
+}
+
+#endif // nsArrayUtils_h__
diff --git a/xpcom/glue/nsBaseHashtable.h b/xpcom/glue/nsBaseHashtable.h
new file mode 100644
index 000000000..f52df3dd1
--- /dev/null
+++ b/xpcom/glue/nsBaseHashtable.h
@@ -0,0 +1,270 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsBaseHashtable_h__
+#define nsBaseHashtable_h__
+
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Move.h"
+#include "nsTHashtable.h"
+#include "nsDebug.h"
+
+template<class KeyClass, class DataType, class UserDataType>
+class nsBaseHashtable; // forward declaration
+
+/**
+ * the private nsTHashtable::EntryType class used by nsBaseHashtable
+ * @see nsTHashtable for the specification of this class
+ * @see nsBaseHashtable for template parameters
+ */
+template<class KeyClass, class DataType>
+class nsBaseHashtableET : public KeyClass
+{
+public:
+  DataType mData;
+  friend class nsTHashtable<nsBaseHashtableET<KeyClass, DataType>>;
+
+private:
+  typedef typename KeyClass::KeyType KeyType;
+  typedef typename KeyClass::KeyTypePointer KeyTypePointer;
+
+  explicit nsBaseHashtableET(KeyTypePointer aKey);
+  nsBaseHashtableET(nsBaseHashtableET<KeyClass, DataType>&& aToMove);
+  ~nsBaseHashtableET();
+};
+
+/**
+ * templated hashtable for simple data types
+ * This class manages simple data types that do not need construction or
+ * destruction.
+ *
+ * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
+ *   for a complete specification.
+ * @param DataType the datatype stored in the hashtable,
+ *   for example, uint32_t or nsCOMPtr.  If UserDataType is not the same,
+ *   DataType must implicitly cast to UserDataType
+ * @param UserDataType the user sees, for example uint32_t or nsISupports*
+ */
+template<class KeyClass, class DataType, class UserDataType>
+class nsBaseHashtable
+  : protected nsTHashtable<nsBaseHashtableET<KeyClass, DataType>>
+{
+  typedef mozilla::fallible_t fallible_t;
+
+public:
+  typedef typename KeyClass::KeyType KeyType;
+  typedef nsBaseHashtableET<KeyClass, DataType> EntryType;
+
+  using nsTHashtable<EntryType>::Contains;
+
+  nsBaseHashtable() {}
+  explicit nsBaseHashtable(uint32_t aInitLength)
+    : nsTHashtable<EntryType>(aInitLength)
+  {
+  }
+
+  /**
+   * Return the number of entries in the table.
+   * @return    number of entries
+   */
+  uint32_t Count() const { return nsTHashtable<EntryType>::Count(); }
+
+  /**
+   * retrieve the value for a key.
+   * @param aKey the key to retreive
+   * @param aData data associated with this key will be placed at this
+   *   pointer.  If you only need to check if the key exists, aData
+   *   may be null.
+   * @return true if the key exists. If key does not exist, aData is not
+   *   modified.
+   */
+  bool Get(KeyType aKey, UserDataType* aData) const
+  {
+    EntryType* ent = this->GetEntry(aKey);
+    if (!ent) {
+      return false;
+    }
+
+    if (aData) {
+      *aData = ent->mData;
+    }
+
+    return true;
+  }
+
+  /**
+   * Get the value, returning a zero-initialized POD or a default-initialized
+   * object if the entry is not present in the table.
+   *
+   * @param aKey the key to retrieve
+   * @return The found value, or UserDataType{} if no entry was found with the
+   *         given key.
+   * @note If zero/default-initialized values are stored in the table, it is
+   *       not possible to distinguish between such a value and a missing entry.
+   */
+  UserDataType Get(KeyType aKey) const
+  {
+    EntryType* ent = this->GetEntry(aKey);
+    if (!ent) {
+      return UserDataType{};
+    }
+
+    return ent->mData;
+  }
+
+  /**
+   * Add key to the table if not already present, and return a reference to its
+   * value.  If key is not already in the table then the value is default
+   * constructed.
+   */
+  DataType& GetOrInsert(const KeyType& aKey)
+  {
+    EntryType* ent = this->GetEntry(aKey);
+    if (ent) {
+      return ent->mData;
+    }
+
+    ent = this->PutEntry(aKey);
+    return ent->mData;
+  }
+
+  /**
+   * put a new value for the associated key
+   * @param aKey the key to put
+   * @param aData the new data
+   * @return always true, unless memory allocation failed
+   */
+  void Put(KeyType aKey, const UserDataType& aData)
+  {
+    if (!Put(aKey, aData, mozilla::fallible)) {
+      NS_ABORT_OOM(this->mTable.EntrySize() * this->mTable.EntryCount());
+    }
+  }
+
+  MOZ_MUST_USE bool Put(KeyType aKey, const UserDataType& aData,
+                        const fallible_t&)
+  {
+    EntryType* ent = this->PutEntry(aKey, mozilla::fallible);
+    if (!ent) {
+      return false;
+    }
+
+    ent->mData = aData;
+
+    return true;
+  }
+
+  /**
+   * remove the data for the associated key
+   * @param aKey the key to remove from the hashtable
+   */
+  void Remove(KeyType aKey) { this->RemoveEntry(aKey); }
+
+  // This is an iterator that also allows entry removal. Example usage:
+  //
+  //   for (auto iter = table.Iter(); !iter.Done(); iter.Next()) {
+  //     const KeyType key = iter.Key();
+  //     const UserDataType data = iter.UserData();
+  //     // or
+  //     const DataType& data = iter.Data();
+  //     // ... do stuff with |key| and/or |data| ...
+  //     // ... possibly call iter.Remove() once ...
+  //   }
+  //
+  class Iterator : public PLDHashTable::Iterator
+  {
+  public:
+    typedef PLDHashTable::Iterator Base;
+
+    explicit Iterator(nsBaseHashtable* aTable) : Base(&aTable->mTable) {}
+    Iterator(Iterator&& aOther) : Base(aOther.mTable) {}
+    ~Iterator() {}
+
+    KeyType Key() const { return static_cast<EntryType*>(Get())->GetKey(); }
+    UserDataType UserData() const
+    {
+      return static_cast<EntryType*>(Get())->mData;
+    }
+    DataType& Data() const { return static_cast<EntryType*>(Get())->mData; }
+
+  private:
+    Iterator() = delete;
+    Iterator(const Iterator&) = delete;
+    Iterator& operator=(const Iterator&) = delete;
+    Iterator& operator=(const Iterator&&) = delete;
+  };
+
+  Iterator Iter() { return Iterator(this); }
+
+  Iterator ConstIter() const
+  {
+    return Iterator(const_cast<nsBaseHashtable*>(this));
+  }
+
+  /**
+   * reset the hashtable, removing all entries
+   */
+  void Clear() { nsTHashtable<EntryType>::Clear(); }
+
+  /**
+   * Measure the size of the table's entry storage. The size of things pointed
+   * to by entries must be measured separately; hence the "Shallow" prefix.
+   *
+   * @param   aMallocSizeOf the function used to measure heap-allocated blocks
+   * @return  the summed size of the table's storage
+   */
+  size_t ShallowSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return this->mTable.ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  /**
+   * Like ShallowSizeOfExcludingThis, but includes sizeof(*this).
+   */
+  size_t ShallowSizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return aMallocSizeOf(this) + ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  /**
+   * Swap the elements in this hashtable with the elements in aOther.
+   */
+  void SwapElements(nsBaseHashtable& aOther)
+  {
+    nsTHashtable<EntryType>::SwapElements(aOther);
+  }
+
+
+#ifdef DEBUG
+  using nsTHashtable<EntryType>::MarkImmutable;
+#endif
+};
+
+//
+// nsBaseHashtableET definitions
+//
+
+template<class KeyClass, class DataType>
+nsBaseHashtableET<KeyClass, DataType>::nsBaseHashtableET(KeyTypePointer aKey)
+  : KeyClass(aKey)
+  , mData()
+{
+}
+
+template<class KeyClass, class DataType>
+nsBaseHashtableET<KeyClass, DataType>::nsBaseHashtableET(
+      nsBaseHashtableET<KeyClass, DataType>&& aToMove)
+  : KeyClass(mozilla::Move(aToMove))
+  , mData(mozilla::Move(aToMove.mData))
+{
+}
+
+template<class KeyClass, class DataType>
+nsBaseHashtableET<KeyClass, DataType>::~nsBaseHashtableET()
+{
+}
+
+#endif // nsBaseHashtable_h__
diff --git a/xpcom/glue/nsCOMArray.cpp b/xpcom/glue/nsCOMArray.cpp
new file mode 100644
index 000000000..3522f7b0d
--- /dev/null
+++ b/xpcom/glue/nsCOMArray.cpp
@@ -0,0 +1,323 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCOMArray.h"
+
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/OperatorNewExtensions.h"
+
+#include "nsCOMPtr.h"
+
+// This specialization is private to nsCOMArray.
+// It exists solely to automatically zero-out newly created array elements.
+template<>
+class nsTArrayElementTraits<nsISupports*>
+{
+  typedef nsISupports* E;
+public:
+  // Zero out the value
+  static inline void Construct(E* aE)
+  {
+    new (mozilla::KnownNotNull, static_cast<void*>(aE)) E();
+  }
+  // Invoke the copy-constructor in place.
+  template<class A>
+  static inline void Construct(E* aE, const A& aArg)
+  {
+    new (mozilla::KnownNotNull, static_cast<void*>(aE)) E(aArg);
+  }
+  // Invoke the destructor in place.
+  static inline void Destruct(E* aE)
+  {
+    aE->~E();
+  }
+};
+
+static void ReleaseObjects(nsTArray<nsISupports*>& aArray);
+
+// implementations of non-trivial methods in nsCOMArray_base
+
+nsCOMArray_base::nsCOMArray_base(const nsCOMArray_base& aOther)
+{
+  // make sure we do only one allocation
+  mArray.SetCapacity(aOther.Count());
+  AppendObjects(aOther);
+}
+
+nsCOMArray_base::~nsCOMArray_base()
+{
+  Clear();
+}
+
+int32_t
+nsCOMArray_base::IndexOf(nsISupports* aObject, uint32_t aStartIndex) const
+{
+  return mArray.IndexOf(aObject, aStartIndex);
+}
+
+int32_t
+nsCOMArray_base::IndexOfObject(nsISupports* aObject) const
+{
+  nsCOMPtr<nsISupports> supports = do_QueryInterface(aObject);
+  if (NS_WARN_IF(!supports)) {
+    return -1;
+  }
+
+  uint32_t i, count;
+  int32_t retval = -1;
+  count = mArray.Length();
+  for (i = 0; i < count; ++i) {
+    nsCOMPtr<nsISupports> arrayItem = do_QueryInterface(mArray[i]);
+    if (arrayItem == supports) {
+      retval = i;
+      break;
+    }
+  }
+  return retval;
+}
+
+bool
+nsCOMArray_base::EnumerateForwards(nsBaseArrayEnumFunc aFunc, void* aData) const
+{
+  for (uint32_t index = 0; index < mArray.Length(); ++index) {
+    if (!(*aFunc)(mArray[index], aData)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool
+nsCOMArray_base::EnumerateBackwards(nsBaseArrayEnumFunc aFunc, void* aData) const
+{
+  for (uint32_t index = mArray.Length(); index--; ) {
+    if (!(*aFunc)(mArray[index], aData)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+int
+nsCOMArray_base::nsCOMArrayComparator(const void* aElement1,
+                                      const void* aElement2,
+                                      void* aData)
+{
+  nsCOMArrayComparatorContext* ctx =
+    static_cast<nsCOMArrayComparatorContext*>(aData);
+  return (*ctx->mComparatorFunc)(*static_cast<nsISupports* const*>(aElement1),
+                                 *static_cast<nsISupports* const*>(aElement2),
+                                 ctx->mData);
+}
+
+void
+nsCOMArray_base::Sort(nsBaseArrayComparatorFunc aFunc, void* aData)
+{
+  if (mArray.Length() > 1) {
+    nsCOMArrayComparatorContext ctx = {aFunc, aData};
+    NS_QuickSort(mArray.Elements(), mArray.Length(), sizeof(nsISupports*),
+                 nsCOMArrayComparator, &ctx);
+  }
+}
+
+bool
+nsCOMArray_base::InsertObjectAt(nsISupports* aObject, int32_t aIndex)
+{
+  if ((uint32_t)aIndex > mArray.Length()) {
+    return false;
+  }
+
+  if (!mArray.InsertElementAt(aIndex, aObject)) {
+    return false;
+  }
+
+  NS_IF_ADDREF(aObject);
+  return true;
+}
+
+void
+nsCOMArray_base::InsertElementAt(uint32_t aIndex, nsISupports* aElement)
+{
+  mArray.InsertElementAt(aIndex, aElement);
+  NS_IF_ADDREF(aElement);
+}
+
+void
+nsCOMArray_base::InsertElementAt(uint32_t aIndex, already_AddRefed<nsISupports> aElement)
+{
+  mArray.InsertElementAt(aIndex, aElement.take());
+}
+
+bool
+nsCOMArray_base::InsertObjectsAt(const nsCOMArray_base& aObjects, int32_t aIndex)
+{
+  if ((uint32_t)aIndex > mArray.Length()) {
+    return false;
+  }
+
+  if (!mArray.InsertElementsAt(aIndex, aObjects.mArray)) {
+    return false;
+  }
+
+  // need to addref all these
+  uint32_t count = aObjects.Length();
+  for (uint32_t i = 0; i < count; ++i) {
+    NS_IF_ADDREF(aObjects[i]);
+  }
+
+  return true;
+}
+
+void
+nsCOMArray_base::InsertElementsAt(uint32_t aIndex,
+                                  const nsCOMArray_base& aElements)
+{
+  mArray.InsertElementsAt(aIndex, aElements.mArray);
+
+  // need to addref all these
+  uint32_t count = aElements.Length();
+  for (uint32_t i = 0; i < count; ++i) {
+    NS_IF_ADDREF(aElements[i]);
+  }
+}
+
+void
+nsCOMArray_base::InsertElementsAt(uint32_t aIndex,
+                                  nsISupports* const* aElements,
+                                  uint32_t aCount)
+{
+  mArray.InsertElementsAt(aIndex, aElements, aCount);
+
+  // need to addref all these
+  for (uint32_t i = 0; i < aCount; ++i) {
+    NS_IF_ADDREF(aElements[i]);
+  }
+}
+
+void
+nsCOMArray_base::ReplaceObjectAt(nsISupports* aObject, int32_t aIndex)
+{
+  mArray.EnsureLengthAtLeast(aIndex + 1);
+  nsISupports* oldObject = mArray[aIndex];
+  // Make sure to addref first, in case aObject == oldObject
+  NS_IF_ADDREF(mArray[aIndex] = aObject);
+  NS_IF_RELEASE(oldObject);
+}
+
+bool
+nsCOMArray_base::RemoveObject(nsISupports* aObject)
+{
+  bool result = mArray.RemoveElement(aObject);
+  if (result) {
+    NS_IF_RELEASE(aObject);
+  }
+  return result;
+}
+
+bool
+nsCOMArray_base::RemoveObjectAt(int32_t aIndex)
+{
+  if (uint32_t(aIndex) < mArray.Length()) {
+    nsISupports* element = mArray[aIndex];
+
+    mArray.RemoveElementAt(aIndex);
+    NS_IF_RELEASE(element);
+    return true;
+  }
+
+  return false;
+}
+
+void
+nsCOMArray_base::RemoveElementAt(uint32_t aIndex)
+{
+  nsISupports* element = mArray[aIndex];
+  mArray.RemoveElementAt(aIndex);
+  NS_IF_RELEASE(element);
+}
+
+bool
+nsCOMArray_base::RemoveObjectsAt(int32_t aIndex, int32_t aCount)
+{
+  if (uint32_t(aIndex) + uint32_t(aCount) <= mArray.Length()) {
+    nsTArray<nsISupports*> elementsToDestroy(aCount);
+    elementsToDestroy.AppendElements(mArray.Elements() + aIndex, aCount);
+    mArray.RemoveElementsAt(aIndex, aCount);
+    ReleaseObjects(elementsToDestroy);
+    return true;
+  }
+
+  return false;
+}
+
+void
+nsCOMArray_base::RemoveElementsAt(uint32_t aIndex, uint32_t aCount)
+{
+  nsTArray<nsISupports*> elementsToDestroy(aCount);
+  elementsToDestroy.AppendElements(mArray.Elements() + aIndex, aCount);
+  mArray.RemoveElementsAt(aIndex, aCount);
+  ReleaseObjects(elementsToDestroy);
+}
+
+// useful for destructors
+void
+ReleaseObjects(nsTArray<nsISupports*>& aArray)
+{
+  for (uint32_t i = 0; i < aArray.Length(); ++i) {
+    NS_IF_RELEASE(aArray[i]);
+  }
+}
+
+void
+nsCOMArray_base::Clear()
+{
+  nsTArray<nsISupports*> objects;
+  objects.SwapElements(mArray);
+  ReleaseObjects(objects);
+}
+
+bool
+nsCOMArray_base::SetCount(int32_t aNewCount)
+{
+  NS_ASSERTION(aNewCount >= 0, "SetCount(negative index)");
+  if (aNewCount < 0) {
+    return false;
+  }
+
+  int32_t count = mArray.Length();
+  if (count > aNewCount) {
+    RemoveObjectsAt(aNewCount, mArray.Length() - aNewCount);
+  }
+  mArray.SetLength(aNewCount);
+  return true;
+}
+
+void
+nsCOMArray_base::Adopt(nsISupports** aElements, uint32_t aSize)
+{
+  Clear();
+  mArray.AppendElements(aElements, aSize);
+
+  // Free the allocated array as well.
+  NS_Free(aElements);
+}
+
+uint32_t
+nsCOMArray_base::Forget(nsISupports*** aElements)
+{
+  uint32_t length = Length();
+  size_t array_size = sizeof(nsISupports*) * length;
+  nsISupports** array = static_cast<nsISupports**>(NS_Alloc(array_size));
+  memmove(array, Elements(), array_size);
+  *aElements = array;
+  // Don't Release the contained pointers; the caller of the method will
+  // do this eventually.
+  mArray.Clear();
+
+  return length;
+}
diff --git a/xpcom/glue/nsCOMArray.h b/xpcom/glue/nsCOMArray.h
new file mode 100644
index 000000000..56d077a2f
--- /dev/null
+++ b/xpcom/glue/nsCOMArray.h
@@ -0,0 +1,473 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCOMArray_h__
+#define nsCOMArray_h__
+
+#include "mozilla/Attributes.h"
+#include "mozilla/MemoryReporting.h"
+
+#include "nsCycleCollectionNoteChild.h"
+#include "nsTArray.h"
+#include "nsISupports.h"
+
+// See below for the definition of nsCOMArray<T>
+
+// a class that's nsISupports-specific, so that we can contain the
+// work of this class in the XPCOM dll
+class nsCOMArray_base
+{
+  friend class nsArrayBase;
+protected:
+  nsCOMArray_base() {}
+  explicit nsCOMArray_base(int32_t aCount) : mArray(aCount) {}
+  nsCOMArray_base(const nsCOMArray_base& aOther);
+  ~nsCOMArray_base();
+
+  int32_t IndexOf(nsISupports* aObject, uint32_t aStartIndex = 0) const;
+  bool Contains(nsISupports* aObject) const
+  {
+    return IndexOf(aObject) != -1;
+  }
+
+  int32_t IndexOfObject(nsISupports* aObject) const;
+  bool ContainsObject(nsISupports* aObject) const
+  {
+    return IndexOfObject(aObject) != -1;
+  }
+
+  typedef bool (*nsBaseArrayEnumFunc)(void* aElement, void* aData);
+
+  // enumerate through the array with a callback.
+  bool EnumerateForwards(nsBaseArrayEnumFunc aFunc, void* aData) const;
+
+  bool EnumerateBackwards(nsBaseArrayEnumFunc aFunc, void* aData) const;
+
+  typedef int (*nsBaseArrayComparatorFunc)(nsISupports* aElement1,
+                                           nsISupports* aElement2,
+                                           void* aData);
+
+  struct nsCOMArrayComparatorContext
+  {
+    nsBaseArrayComparatorFunc mComparatorFunc;
+    void* mData;
+  };
+
+  static int nsCOMArrayComparator(const void* aElement1, const void* aElement2,
+                                  void* aData);
+  void Sort(nsBaseArrayComparatorFunc aFunc, void* aData);
+
+  bool InsertObjectAt(nsISupports* aObject, int32_t aIndex);
+  void InsertElementAt(uint32_t aIndex, nsISupports* aElement);
+  void InsertElementAt(uint32_t aIndex, already_AddRefed<nsISupports> aElement);
+  bool InsertObjectsAt(const nsCOMArray_base& aObjects, int32_t aIndex);
+  void InsertElementsAt(uint32_t aIndex, const nsCOMArray_base& aElements);
+  void InsertElementsAt(uint32_t aIndex, nsISupports* const* aElements,
+                        uint32_t aCount);
+  void ReplaceObjectAt(nsISupports* aObject, int32_t aIndex);
+  void ReplaceElementAt(uint32_t aIndex, nsISupports* aElement)
+  {
+    nsISupports* oldElement = mArray[aIndex];
+    NS_IF_ADDREF(mArray[aIndex] = aElement);
+    NS_IF_RELEASE(oldElement);
+  }
+  bool AppendObject(nsISupports* aObject)
+  {
+    return InsertObjectAt(aObject, Count());
+  }
+  void AppendElement(nsISupports* aElement)
+  {
+    InsertElementAt(Length(), aElement);
+  }
+  void AppendElement(already_AddRefed<nsISupports> aElement)
+  {
+    InsertElementAt(Length(), mozilla::Move(aElement));
+  }
+
+  bool AppendObjects(const nsCOMArray_base& aObjects)
+  {
+    return InsertObjectsAt(aObjects, Count());
+  }
+  void AppendElements(const nsCOMArray_base& aElements)
+  {
+    return InsertElementsAt(Length(), aElements);
+  }
+  void AppendElements(nsISupports* const* aElements, uint32_t aCount)
+  {
+    return InsertElementsAt(Length(), aElements, aCount);
+  }
+  bool RemoveObject(nsISupports* aObject);
+  nsISupports** Elements() { return mArray.Elements(); }
+  void SwapElements(nsCOMArray_base& aOther)
+  {
+    mArray.SwapElements(aOther.mArray);
+  }
+
+  void Adopt(nsISupports** aElements, uint32_t aCount);
+  uint32_t Forget(nsISupports*** aElements);
+public:
+  // elements in the array (including null elements!)
+  int32_t Count() const { return mArray.Length(); }
+  // nsTArray-compatible version
+  uint32_t Length() const { return mArray.Length(); }
+  bool IsEmpty() const { return mArray.IsEmpty(); }
+
+  // If the array grows, the newly created entries will all be null;
+  // if the array shrinks, the excess entries will all be released.
+  bool SetCount(int32_t aNewCount);
+  // nsTArray-compatible version
+  void TruncateLength(uint32_t aNewLength)
+  {
+    if (mArray.Length() > aNewLength) {
+      RemoveElementsAt(aNewLength, mArray.Length() - aNewLength);
+    }
+  }
+
+  // remove all elements in the array, and call NS_RELEASE on each one
+  void Clear();
+
+  nsISupports* ObjectAt(int32_t aIndex) const { return mArray[aIndex]; }
+  // nsTArray-compatible version
+  nsISupports* ElementAt(uint32_t aIndex) const { return mArray[aIndex]; }
+
+  nsISupports* SafeObjectAt(int32_t aIndex) const
+  {
+    return mArray.SafeElementAt(aIndex, nullptr);
+  }
+  // nsTArray-compatible version
+  nsISupports* SafeElementAt(uint32_t aIndex) const
+  {
+    return mArray.SafeElementAt(aIndex, nullptr);
+  }
+
+  nsISupports* operator[](int32_t aIndex) const { return mArray[aIndex]; }
+
+  // remove an element at a specific position, shrinking the array
+  // as necessary
+  bool RemoveObjectAt(int32_t aIndex);
+  // nsTArray-compatible version
+  void RemoveElementAt(uint32_t aIndex);
+
+  // remove a range of elements at a specific position, shrinking the array
+  // as necessary
+  bool RemoveObjectsAt(int32_t aIndex, int32_t aCount);
+  // nsTArray-compatible version
+  void RemoveElementsAt(uint32_t aIndex, uint32_t aCount);
+
+  void SwapElementsAt(uint32_t aIndex1, uint32_t aIndex2)
+  {
+    nsISupports* tmp = mArray[aIndex1];
+    mArray[aIndex1] = mArray[aIndex2];
+    mArray[aIndex2] = tmp;
+  }
+
+  // Ensures there is enough space to store a total of aCapacity objects.
+  // This method never deletes any objects.
+  void SetCapacity(uint32_t aCapacity) { mArray.SetCapacity(aCapacity); }
+  uint32_t Capacity() { return mArray.Capacity(); }
+
+  // Measures the size of the array's element storage. If you want to measure
+  // anything hanging off the array, you must iterate over the elements and
+  // measure them individually; hence the "Shallow" prefix. Note that because
+  // each element in an nsCOMArray<T> is actually a T* any such iteration
+  // should use a SizeOfIncludingThis() function on each element rather than a
+  // SizeOfExcludingThis() function, so that the memory taken by the T itself
+  // is included as well as anything it points to.
+  size_t ShallowSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return mArray.ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+
+private:
+
+  // the actual storage
+  nsTArray<nsISupports*> mArray;
+
+  // don't implement these, defaults will muck with refcounts!
+  nsCOMArray_base& operator=(const nsCOMArray_base& aOther) = delete;
+};
+
+inline void
+ImplCycleCollectionUnlink(nsCOMArray_base& aField)
+{
+  aField.Clear();
+}
+
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            nsCOMArray_base& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  aFlags |= CycleCollectionEdgeNameArrayFlag;
+  int32_t length = aField.Count();
+  for (int32_t i = 0; i < length; ++i) {
+    CycleCollectionNoteChild(aCallback, aField[i], aName, aFlags);
+  }
+}
+
+
+// a non-XPCOM, refcounting array of XPCOM objects
+// used as a member variable or stack variable - this object is NOT
+// refcounted, but the objects that it holds are
+//
+// most of the read-only accessors like ObjectAt()/etc do NOT refcount
+// on the way out. This means that you can do one of two things:
+//
+// * does an addref, but holds onto a reference
+// nsCOMPtr<T> foo = array[i];
+//
+// * avoids the refcount, but foo might go stale if array[i] is ever
+// * modified/removed. Be careful not to NS_RELEASE(foo)!
+// T* foo = array[i];
+//
+// This array will accept null as an argument for any object, and will store
+// null in the array. But that also means that methods like ObjectAt() may
+// return null when referring to an existing, but null entry in the array.
+template<class T>
+class nsCOMArray : public nsCOMArray_base
+{
+public:
+  nsCOMArray() {}
+  explicit nsCOMArray(int32_t aCount) : nsCOMArray_base(aCount) {}
+  explicit nsCOMArray(const nsCOMArray<T>& aOther) : nsCOMArray_base(aOther) {}
+  nsCOMArray(nsCOMArray<T>&& aOther) { SwapElements(aOther); }
+  ~nsCOMArray() {}
+
+  // We have a move assignment operator, but no copy assignment operator.
+  nsCOMArray<T>& operator=(nsCOMArray<T> && aOther)
+  {
+    SwapElements(aOther);
+    return *this;
+  }
+
+  // these do NOT refcount on the way out, for speed
+  T* ObjectAt(int32_t aIndex) const
+  {
+    return static_cast<T*>(nsCOMArray_base::ObjectAt(aIndex));
+  }
+  // nsTArray-compatible version
+  T* ElementAt(uint32_t aIndex) const
+  {
+    return static_cast<T*>(nsCOMArray_base::ElementAt(aIndex));
+  }
+
+  // these do NOT refcount on the way out, for speed
+  T* SafeObjectAt(int32_t aIndex) const
+  {
+    return static_cast<T*>(nsCOMArray_base::SafeObjectAt(aIndex));
+  }
+  // nsTArray-compatible version
+  T* SafeElementAt(uint32_t aIndex) const
+  {
+    return static_cast<T*>(nsCOMArray_base::SafeElementAt(aIndex));
+  }
+
+  // indexing operator for syntactic sugar
+  T* operator[](int32_t aIndex) const { return ObjectAt(aIndex); }
+
+  // index of the element in question.. does NOT refcount
+  // note: this does not check COM object identity. Use
+  // IndexOfObject() for that purpose
+  int32_t IndexOf(T* aObject, uint32_t aStartIndex = 0) const
+  {
+    return nsCOMArray_base::IndexOf(aObject, aStartIndex);
+  }
+  bool Contains(T* aObject) const
+  {
+    return nsCOMArray_base::Contains(aObject);
+  }
+
+  // index of the element in question.. be careful!
+  // this is much slower than IndexOf() because it uses
+  // QueryInterface to determine actual COM identity of the object
+  // if you need to do this frequently then consider enforcing
+  // COM object identity before adding/comparing elements
+  int32_t IndexOfObject(T* aObject) const
+  {
+    return nsCOMArray_base::IndexOfObject(aObject);
+  }
+  bool ContainsObject(nsISupports* aObject) const
+  {
+    return nsCOMArray_base::ContainsObject(aObject);
+  }
+
+  // inserts aObject at aIndex, shifting the objects at aIndex and
+  // later to make space
+  bool InsertObjectAt(T* aObject, int32_t aIndex)
+  {
+    return nsCOMArray_base::InsertObjectAt(aObject, aIndex);
+  }
+  // nsTArray-compatible version
+  void InsertElementAt(uint32_t aIndex, T* aElement)
+  {
+    nsCOMArray_base::InsertElementAt(aIndex, aElement);
+  }
+
+  // inserts the objects from aObject at aIndex, shifting the
+  // objects at aIndex and later to make space
+  bool InsertObjectsAt(const nsCOMArray<T>& aObjects, int32_t aIndex)
+  {
+    return nsCOMArray_base::InsertObjectsAt(aObjects, aIndex);
+  }
+  // nsTArray-compatible version
+  void InsertElementsAt(uint32_t aIndex, const nsCOMArray<T>& aElements)
+  {
+    nsCOMArray_base::InsertElementsAt(aIndex, aElements);
+  }
+  void InsertElementsAt(uint32_t aIndex, T* const* aElements, uint32_t aCount)
+  {
+    nsCOMArray_base::InsertElementsAt(
+      aIndex, reinterpret_cast<nsISupports* const*>(aElements), aCount);
+  }
+
+  // replaces an existing element. Warning: if the array grows,
+  // the newly created entries will all be null
+  void ReplaceObjectAt(T* aObject, int32_t aIndex)
+  {
+    nsCOMArray_base::ReplaceObjectAt(aObject, aIndex);
+  }
+  // nsTArray-compatible version
+  void ReplaceElementAt(uint32_t aIndex, T* aElement)
+  {
+    nsCOMArray_base::ReplaceElementAt(aIndex, aElement);
+  }
+
+  // Enumerator callback function. Return false to stop
+  // Here's a more readable form:
+  // bool enumerate(T* aElement, void* aData)
+  typedef bool (*nsCOMArrayEnumFunc)(T* aElement, void* aData);
+
+  // enumerate through the array with a callback.
+  bool EnumerateForwards(nsCOMArrayEnumFunc aFunc, void* aData)
+  {
+    return nsCOMArray_base::EnumerateForwards(nsBaseArrayEnumFunc(aFunc),
+                                              aData);
+  }
+
+  bool EnumerateBackwards(nsCOMArrayEnumFunc aFunc, void* aData)
+  {
+    return nsCOMArray_base::EnumerateBackwards(nsBaseArrayEnumFunc(aFunc),
+                                               aData);
+  }
+
+  typedef int (*nsCOMArrayComparatorFunc)(T* aElement1, T* aElement2,
+                                          void* aData);
+
+  void Sort(nsCOMArrayComparatorFunc aFunc, void* aData)
+  {
+    nsCOMArray_base::Sort(nsBaseArrayComparatorFunc(aFunc), aData);
+  }
+
+  // append an object, growing the array as necessary
+  bool AppendObject(T* aObject)
+  {
+    return nsCOMArray_base::AppendObject(aObject);
+  }
+  // nsTArray-compatible version
+  void AppendElement(T* aElement)
+  {
+    nsCOMArray_base::AppendElement(aElement);
+  }
+  void AppendElement(already_AddRefed<T> aElement)
+  {
+    nsCOMArray_base::AppendElement(mozilla::Move(aElement));
+  }
+
+  // append objects, growing the array as necessary
+  bool AppendObjects(const nsCOMArray<T>& aObjects)
+  {
+    return nsCOMArray_base::AppendObjects(aObjects);
+  }
+  // nsTArray-compatible version
+  void AppendElements(const nsCOMArray<T>& aElements)
+  {
+    return nsCOMArray_base::AppendElements(aElements);
+  }
+  void AppendElements(T* const* aElements, uint32_t aCount)
+  {
+    InsertElementsAt(Length(), aElements, aCount);
+  }
+
+  // remove the first instance of the given object and shrink the
+  // array as necessary
+  // Warning: if you pass null here, it will remove the first null element
+  bool RemoveObject(T* aObject)
+  {
+    return nsCOMArray_base::RemoveObject(aObject);
+  }
+  // nsTArray-compatible version
+  bool RemoveElement(T* aElement)
+  {
+    return nsCOMArray_base::RemoveObject(aElement);
+  }
+
+  T** Elements()
+  {
+    return reinterpret_cast<T**>(nsCOMArray_base::Elements());
+  }
+  void SwapElements(nsCOMArray<T>& aOther)
+  {
+    nsCOMArray_base::SwapElements(aOther);
+  }
+
+  /**
+   * Adopt parameters that resulted from an XPIDL outparam. The aElements
+   * parameter will be freed as a result of the call.
+   *
+   * Example usage:
+   * nsCOMArray<nsISomeInterface> array;
+   * nsISomeInterface** elements;
+   * uint32_t length;
+   * ptr->GetSomeArray(&elements, &length);
+   * array.Adopt(elements, length);
+   */
+  void Adopt(T** aElements, uint32_t aSize)
+  {
+    nsCOMArray_base::Adopt(reinterpret_cast<nsISupports**>(aElements), aSize);
+  }
+
+  /**
+   * Export the contents of this array to an XPIDL outparam. The array will be
+   * Clear()'d after this operation.
+   *
+   * Example usage:
+   * nsCOMArray<nsISomeInterface> array;
+   * *length = array.Forget(retval);
+   */
+  uint32_t Forget(T*** aElements)
+  {
+    return nsCOMArray_base::Forget(reinterpret_cast<nsISupports***>(aElements));
+  }
+
+private:
+
+  // don't implement these!
+  nsCOMArray<T>& operator=(const nsCOMArray<T>& aOther) = delete;
+};
+
+template<typename T>
+inline void
+ImplCycleCollectionUnlink(nsCOMArray<T>& aField)
+{
+  aField.Clear();
+}
+
+template<typename E>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            nsCOMArray<E>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  aFlags |= CycleCollectionEdgeNameArrayFlag;
+  int32_t length = aField.Count();
+  for (int32_t i = 0; i < length; ++i) {
+    CycleCollectionNoteChild(aCallback, aField[i], aName, aFlags);
+  }
+}
+
+#endif
diff --git a/xpcom/glue/nsCOMPtr.cpp b/xpcom/glue/nsCOMPtr.cpp
new file mode 100644
index 000000000..263fa62c2
--- /dev/null
+++ b/xpcom/glue/nsCOMPtr.cpp
@@ -0,0 +1,128 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCOMPtr.h"
+
+nsresult
+nsQueryInterface::operator()(const nsIID& aIID, void** aAnswer) const
+{
+  nsresult status;
+  if (mRawPtr) {
+    status = mRawPtr->QueryInterface(aIID, aAnswer);
+  } else {
+    status = NS_ERROR_NULL_POINTER;
+  }
+
+  return status;
+}
+
+nsresult
+nsQueryInterfaceWithError::operator()(const nsIID& aIID, void** aAnswer) const
+{
+  nsresult status;
+  if (mRawPtr) {
+    status = mRawPtr->QueryInterface(aIID, aAnswer);
+  } else {
+    status = NS_ERROR_NULL_POINTER;
+  }
+
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
+
+void
+nsCOMPtr_base::assign_with_AddRef(nsISupports* aRawPtr)
+{
+  if (aRawPtr) {
+    NSCAP_ADDREF(this, aRawPtr);
+  }
+  assign_assuming_AddRef(aRawPtr);
+}
+
+void
+nsCOMPtr_base::assign_from_qi(const nsQueryInterface aQI, const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aQI(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<nsISupports*>(newRawPtr));
+}
+
+void
+nsCOMPtr_base::assign_from_qi_with_error(const nsQueryInterfaceWithError& aQI,
+                                         const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aQI(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<nsISupports*>(newRawPtr));
+}
+
+void
+nsCOMPtr_base::assign_from_gs_cid(const nsGetServiceByCID aGS,
+                                  const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aGS(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<nsISupports*>(newRawPtr));
+}
+
+void
+nsCOMPtr_base::assign_from_gs_cid_with_error(
+    const nsGetServiceByCIDWithError& aGS, const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aGS(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<nsISupports*>(newRawPtr));
+}
+
+void
+nsCOMPtr_base::assign_from_gs_contractid(const nsGetServiceByContractID aGS,
+                                         const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aGS(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<nsISupports*>(newRawPtr));
+}
+
+void
+nsCOMPtr_base::assign_from_gs_contractid_with_error(
+    const nsGetServiceByContractIDWithError& aGS, const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aGS(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<nsISupports*>(newRawPtr));
+}
+
+void
+nsCOMPtr_base::assign_from_helper(const nsCOMPtr_helper& aHelper,
+                                  const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aHelper(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<nsISupports*>(newRawPtr));
+}
+
+void**
+nsCOMPtr_base::begin_assignment()
+{
+  assign_assuming_AddRef(nullptr);
+  return reinterpret_cast<void**>(&mRawPtr);
+}
diff --git a/xpcom/glue/nsCOMPtr.h b/xpcom/glue/nsCOMPtr.h
new file mode 100644
index 000000000..373f55cbb
--- /dev/null
+++ b/xpcom/glue/nsCOMPtr.h
@@ -0,0 +1,1472 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCOMPtr_h___
+#define nsCOMPtr_h___
+
+/*
+ * Having problems?
+ *
+ * See the User Manual at:
+ *   http://www.mozilla.org/projects/xpcom/nsCOMPtr.html
+ *
+ *
+ * nsCOMPtr
+ *   better than a raw pointer
+ * for owning objects
+ *                      -- scc
+ */
+
+#include "mozilla/AlreadyAddRefed.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Move.h"
+#include "mozilla/TypeTraits.h"
+
+#include "nsDebug.h" // for |NS_ASSERTION|
+#include "nsISupportsUtils.h" // for |nsresult|, |NS_ADDREF|, |NS_GET_TEMPLATE_IID| et al
+#include "mozilla/RefPtr.h"
+
+#include "nsCycleCollectionNoteChild.h"
+
+
+/*
+ * WARNING: This file defines several macros for internal use only. These
+ * macros begin with the prefix |NSCAP_|. Do not use these macros in your own
+ * code. They are for internal use only for cross-platform compatibility, and
+ * are subject to change without notice.
+ */
+
+
+#ifdef _MSC_VER
+  // Under VC++, we win by inlining StartAssignment.
+  #define NSCAP_FEATURE_INLINE_STARTASSIGNMENT
+
+  // Also under VC++, at the highest warning level, we are overwhelmed with
+  // warnings about (unused) inline functions being removed. This is to be
+  // expected with templates, so we disable the warning.
+  #pragma warning( disable: 4514 )
+#endif
+
+#define NSCAP_FEATURE_USE_BASE
+
+#ifdef DEBUG
+  #define NSCAP_FEATURE_TEST_DONTQUERY_CASES
+  #undef NSCAP_FEATURE_USE_BASE
+#endif
+
+#ifdef __GNUC__
+  // Our use of nsCOMPtr_base::mRawPtr violates the C++ standard's aliasing
+  // rules. Mark it with the may_alias attribute so that gcc 3.3 and higher
+  // don't reorder instructions based on aliasing assumptions for
+  // this variable.  Fortunately, gcc versions < 3.3 do not do any
+  // optimizations that break nsCOMPtr.
+
+  #define NS_MAY_ALIAS_PTR(t)    t*  __attribute__((__may_alias__))
+#else
+  #define NS_MAY_ALIAS_PTR(t)    t*
+#endif
+
+#if defined(NSCAP_DISABLE_DEBUG_PTR_TYPES)
+  #define NSCAP_FEATURE_USE_BASE
+#endif
+
+/*
+ * The following three macros (NSCAP_ADDREF, NSCAP_RELEASE, and
+ * NSCAP_LOG_ASSIGNMENT) allow external clients the ability to add logging or
+ * other interesting debug facilities. In fact, if you want |nsCOMPtr| to
+ * participate in the standard logging facility, you provide
+ * (e.g., in "nsISupportsImpl.h") suitable definitions
+ *
+ *   #define NSCAP_ADDREF(this, ptr)         NS_ADDREF(ptr)
+ *   #define NSCAP_RELEASE(this, ptr)        NS_RELEASE(ptr)
+ */
+
+#ifndef NSCAP_ADDREF
+  #define NSCAP_ADDREF(this, ptr)     (ptr)->AddRef()
+#endif
+
+#ifndef NSCAP_RELEASE
+  #define NSCAP_RELEASE(this, ptr)    (ptr)->Release()
+#endif
+
+// Clients can define |NSCAP_LOG_ASSIGNMENT| to perform logging.
+#ifdef NSCAP_LOG_ASSIGNMENT
+  // Remember that |NSCAP_LOG_ASSIGNMENT| was defined by some client so that we
+  // know to instantiate |~nsGetterAddRefs| in turn to note the external
+  // assignment into the |nsCOMPtr|.
+  #define NSCAP_LOG_EXTERNAL_ASSIGNMENT
+#else
+    // ...otherwise, just strip it out of the code
+  #define NSCAP_LOG_ASSIGNMENT(this, ptr)
+#endif
+
+#ifndef NSCAP_LOG_RELEASE
+  #define NSCAP_LOG_RELEASE(this, ptr)
+#endif
+
+namespace mozilla {
+template<class T> class OwningNonNull;
+} // namespace mozilla
+
+template<class T>
+inline already_AddRefed<T>
+dont_AddRef(T* aRawPtr)
+{
+  return already_AddRefed<T>(aRawPtr);
+}
+
+template<class T>
+inline already_AddRefed<T>&&
+dont_AddRef(already_AddRefed<T>&& aAlreadyAddRefedPtr)
+{
+  return mozilla::Move(aAlreadyAddRefedPtr);
+}
+
+
+/*
+ * An nsCOMPtr_helper transforms commonly called getters into typesafe forms
+ * that are more convenient to call, and more efficient to use with |nsCOMPtr|s.
+ * Good candidates for helpers are |QueryInterface()|, |CreateInstance()|, etc.
+ *
+ * Here are the rules for a helper:
+ *   - it implements |operator()| to produce an interface pointer
+ *   - (except for its name) |operator()| is a valid [XP]COM `getter'
+ *   - the interface pointer that it returns is already |AddRef()|ed (as from
+ *     any good getter)
+ *   - it matches the type requested with the supplied |nsIID| argument
+ *   - its constructor provides an optional |nsresult*| that |operator()| can
+ *     fill in with an error when it is executed
+ *
+ * See |class nsGetInterface| for an example.
+ */
+class MOZ_STACK_CLASS nsCOMPtr_helper
+{
+public:
+  virtual nsresult NS_FASTCALL operator()(const nsIID&, void**) const = 0;
+};
+
+/*
+ * nsQueryInterface could have been implemented as an nsCOMPtr_helper to avoid
+ * adding specialized machinery in nsCOMPtr, but do_QueryInterface is called
+ * often enough that the codesize savings are big enough to warrant the
+ * specialcasing.
+ */
+class MOZ_STACK_CLASS nsQueryInterface final
+{
+public:
+  explicit
+  nsQueryInterface(nsISupports* aRawPtr) : mRawPtr(aRawPtr) {}
+
+  nsresult NS_FASTCALL operator()(const nsIID& aIID, void**) const;
+
+private:
+  nsISupports* MOZ_OWNING_REF mRawPtr;
+};
+
+class nsQueryInterfaceWithError final
+{
+public:
+  nsQueryInterfaceWithError(nsISupports* aRawPtr, nsresult* aError)
+    : mRawPtr(aRawPtr)
+    , mErrorPtr(aError)
+  {
+  }
+
+  nsresult NS_FASTCALL operator()(const nsIID& aIID, void**) const;
+
+private:
+  nsISupports* MOZ_OWNING_REF mRawPtr;
+  nsresult* mErrorPtr;
+};
+
+inline nsQueryInterface
+do_QueryInterface(nsISupports* aRawPtr)
+{
+  return nsQueryInterface(aRawPtr);
+}
+
+inline nsQueryInterfaceWithError
+do_QueryInterface(nsISupports* aRawPtr, nsresult* aError)
+{
+  return nsQueryInterfaceWithError(aRawPtr, aError);
+}
+
+template<class T>
+inline void
+do_QueryInterface(already_AddRefed<T>&)
+{
+  // This signature exists solely to _stop_ you from doing the bad thing.
+  // Saying |do_QueryInterface()| on a pointer that is not otherwise owned by
+  // someone else is an automatic leak. See bug 8221.
+}
+
+template<class T>
+inline void
+do_QueryInterface(already_AddRefed<T>&, nsresult*)
+{
+  // This signature exists solely to _stop_ you from doing the bad thing.
+  // Saying |do_QueryInterface()| on a pointer that is not otherwise owned by
+  // someone else is an automatic leak. See bug 8221.
+}
+
+
+////////////////////////////////////////////////////////////////////////////
+// Using servicemanager with COMPtrs
+class nsGetServiceByCID final
+{
+public:
+  explicit nsGetServiceByCID(const nsCID& aCID) : mCID(aCID) {}
+
+  nsresult NS_FASTCALL operator()(const nsIID&, void**) const;
+
+private:
+  const nsCID& mCID;
+};
+
+class nsGetServiceByCIDWithError final
+{
+public:
+  nsGetServiceByCIDWithError(const nsCID& aCID, nsresult* aErrorPtr)
+    : mCID(aCID)
+    , mErrorPtr(aErrorPtr)
+  {
+  }
+
+  nsresult NS_FASTCALL operator()(const nsIID&, void**) const;
+
+private:
+  const nsCID& mCID;
+  nsresult* mErrorPtr;
+};
+
+class nsGetServiceByContractID final
+{
+public:
+  explicit nsGetServiceByContractID(const char* aContractID)
+    : mContractID(aContractID)
+  {
+  }
+
+  nsresult NS_FASTCALL operator()(const nsIID&, void**) const;
+
+private:
+  const char* mContractID;
+};
+
+class nsGetServiceByContractIDWithError final
+{
+public:
+  nsGetServiceByContractIDWithError(const char* aContractID, nsresult* aErrorPtr)
+    : mContractID(aContractID)
+    , mErrorPtr(aErrorPtr)
+  {
+  }
+
+  nsresult NS_FASTCALL operator()(const nsIID&, void**) const;
+
+private:
+  const char* mContractID;
+  nsresult* mErrorPtr;
+};
+
+/**
+ * Factors implementation for all template versions of nsCOMPtr.
+ *
+ * Here's the way people normally do things like this:
+ *
+ *   template<class T> class Foo { ... };
+ *   template<> class Foo<void*> { ... };
+ *   template<class T> class Foo<T*> : private Foo<void*> { ... };
+ */
+class nsCOMPtr_base
+{
+public:
+  explicit nsCOMPtr_base(nsISupports* aRawPtr = nullptr) : mRawPtr(aRawPtr) {}
+
+  NS_CONSTRUCTOR_FASTCALL ~nsCOMPtr_base()
+  {
+    NSCAP_LOG_RELEASE(this, mRawPtr);
+    if (mRawPtr) {
+      NSCAP_RELEASE(this, mRawPtr);
+    }
+  }
+
+  void NS_FASTCALL
+  assign_with_AddRef(nsISupports*);
+  void NS_FASTCALL
+  assign_from_qi(const nsQueryInterface, const nsIID&);
+  void NS_FASTCALL
+  assign_from_qi_with_error(const nsQueryInterfaceWithError&, const nsIID&);
+  void NS_FASTCALL
+  assign_from_gs_cid(const nsGetServiceByCID, const nsIID&);
+  void NS_FASTCALL
+  assign_from_gs_cid_with_error(const nsGetServiceByCIDWithError&, const nsIID&);
+  void NS_FASTCALL
+  assign_from_gs_contractid(const nsGetServiceByContractID, const nsIID&);
+  void NS_FASTCALL
+  assign_from_gs_contractid_with_error(const nsGetServiceByContractIDWithError&,
+                                       const nsIID&);
+  void NS_FASTCALL
+  assign_from_helper(const nsCOMPtr_helper&, const nsIID&);
+  void** NS_FASTCALL
+  begin_assignment();
+
+protected:
+  NS_MAY_ALIAS_PTR(nsISupports) MOZ_OWNING_REF mRawPtr;
+
+  void assign_assuming_AddRef(nsISupports* aNewPtr)
+  {
+    // |AddRef()|ing the new value (before entering this function) before
+    // |Release()|ing the old lets us safely ignore the self-assignment case.
+    // We must, however, be careful only to |Release()| _after_ doing the
+    // assignment, in case the |Release()| leads to our _own_ destruction,
+    // which would, in turn, cause an incorrect second |Release()| of our old
+    // pointer. Thank <waterson@netscape.com> for discovering this.
+    nsISupports* oldPtr = mRawPtr;
+    mRawPtr = aNewPtr;
+    NSCAP_LOG_ASSIGNMENT(this, aNewPtr);
+    NSCAP_LOG_RELEASE(this, oldPtr);
+    if (oldPtr) {
+      NSCAP_RELEASE(this, oldPtr);
+    }
+  }
+};
+
+// template<class T> class nsGetterAddRefs;
+
+// Helper for assert_validity method
+template<class T>
+char (&TestForIID(decltype(&NS_GET_TEMPLATE_IID(T))))[2];
+template<class T>
+char TestForIID(...);
+
+template<class T>
+class nsCOMPtr final
+#ifdef NSCAP_FEATURE_USE_BASE
+  : private nsCOMPtr_base
+#endif
+{
+
+#ifdef NSCAP_FEATURE_USE_BASE
+  #define NSCAP_CTOR_BASE(x) nsCOMPtr_base(x)
+#else
+  #define NSCAP_CTOR_BASE(x) mRawPtr(x)
+
+private:
+  void assign_with_AddRef(nsISupports*);
+  void assign_from_qi(const nsQueryInterface, const nsIID&);
+  void assign_from_qi_with_error(const nsQueryInterfaceWithError&, const nsIID&);
+  void assign_from_gs_cid(const nsGetServiceByCID, const nsIID&);
+  void assign_from_gs_cid_with_error(const nsGetServiceByCIDWithError&,
+                                     const nsIID&);
+  void assign_from_gs_contractid(const nsGetServiceByContractID, const nsIID&);
+  void assign_from_gs_contractid_with_error(
+    const nsGetServiceByContractIDWithError&, const nsIID&);
+  void assign_from_helper(const nsCOMPtr_helper&, const nsIID&);
+  void** begin_assignment();
+
+  void assign_assuming_AddRef(T* aNewPtr)
+  {
+    T* oldPtr = mRawPtr;
+    mRawPtr = aNewPtr;
+    NSCAP_LOG_ASSIGNMENT(this, aNewPtr);
+    NSCAP_LOG_RELEASE(this, oldPtr);
+    if (oldPtr) {
+      NSCAP_RELEASE(this, oldPtr);
+    }
+  }
+
+private:
+  T* MOZ_OWNING_REF mRawPtr;
+#endif
+
+  void assert_validity()
+  {
+    static_assert(1 < sizeof(TestForIID<T>(nullptr)), "nsCOMPtr only works "
+                  "for types with IIDs.  Either use RefPtr; add an IID to "
+                  "your type with NS_DECLARE_STATIC_IID_ACCESSOR/"
+                  "NS_DEFINE_STATIC_IID_ACCESSOR; or make the nsCOMPtr point "
+                  "to a base class with an IID.");
+  }
+
+public:
+  typedef T element_type;
+
+#ifndef NSCAP_FEATURE_USE_BASE
+  ~nsCOMPtr()
+  {
+    NSCAP_LOG_RELEASE(this, mRawPtr);
+    if (mRawPtr) {
+      NSCAP_RELEASE(this, mRawPtr);
+    }
+  }
+#endif
+
+#ifdef NSCAP_FEATURE_TEST_DONTQUERY_CASES
+  void Assert_NoQueryNeeded()
+  {
+    if (mRawPtr) {
+      nsCOMPtr<T> query_result(do_QueryInterface(mRawPtr));
+      NS_ASSERTION(query_result.get() == mRawPtr, "QueryInterface needed");
+    }
+  }
+
+  #define NSCAP_ASSERT_NO_QUERY_NEEDED() Assert_NoQueryNeeded();
+#else
+  #define NSCAP_ASSERT_NO_QUERY_NEEDED()
+#endif
+
+
+  // Constructors
+
+  nsCOMPtr()
+    : NSCAP_CTOR_BASE(nullptr)
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+  }
+
+  MOZ_IMPLICIT nsCOMPtr(decltype(nullptr))
+    : NSCAP_CTOR_BASE(nullptr)
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+  }
+
+  nsCOMPtr(const nsCOMPtr<T>& aSmartPtr)
+    : NSCAP_CTOR_BASE(aSmartPtr.mRawPtr)
+  {
+    assert_validity();
+    if (mRawPtr) {
+      NSCAP_ADDREF(this, mRawPtr);
+    }
+    NSCAP_LOG_ASSIGNMENT(this, aSmartPtr.mRawPtr);
+  }
+
+  nsCOMPtr(nsCOMPtr<T>&& aSmartPtr)
+    : NSCAP_CTOR_BASE(aSmartPtr.mRawPtr)
+  {
+    assert_validity();
+    aSmartPtr.mRawPtr = nullptr;
+    NSCAP_LOG_ASSIGNMENT(this, mRawPtr);
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+  }
+
+  MOZ_IMPLICIT nsCOMPtr(T* aRawPtr)
+    : NSCAP_CTOR_BASE(aRawPtr)
+  {
+    assert_validity();
+    if (mRawPtr) {
+      NSCAP_ADDREF(this, mRawPtr);
+    }
+    NSCAP_LOG_ASSIGNMENT(this, aRawPtr);
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+  }
+
+  MOZ_IMPLICIT nsCOMPtr(already_AddRefed<T>& aSmartPtr)
+    : NSCAP_CTOR_BASE(aSmartPtr.take())
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, mRawPtr);
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+  }
+
+  // Construct from |otherComPtr.forget()|.
+  MOZ_IMPLICIT nsCOMPtr(already_AddRefed<T>&& aSmartPtr)
+    : NSCAP_CTOR_BASE(aSmartPtr.take())
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, mRawPtr);
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+  }
+
+  // Construct from |already_AddRefed|.
+  template<typename U>
+  MOZ_IMPLICIT nsCOMPtr(already_AddRefed<U>& aSmartPtr)
+    : NSCAP_CTOR_BASE(static_cast<T*>(aSmartPtr.take()))
+  {
+    assert_validity();
+    // But make sure that U actually inherits from T.
+    static_assert(mozilla::IsBaseOf<T, U>::value,
+                  "U is not a subclass of T");
+    NSCAP_LOG_ASSIGNMENT(this, static_cast<T*>(mRawPtr));
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+  }
+
+  // Construct from |otherComPtr.forget()|.
+  template<typename U>
+  MOZ_IMPLICIT nsCOMPtr(already_AddRefed<U>&& aSmartPtr)
+    : NSCAP_CTOR_BASE(static_cast<T*>(aSmartPtr.take()))
+  {
+    assert_validity();
+    // But make sure that U actually inherits from T.
+    static_assert(mozilla::IsBaseOf<T, U>::value,
+                  "U is not a subclass of T");
+    NSCAP_LOG_ASSIGNMENT(this, static_cast<T*>(mRawPtr));
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+  }
+
+  // Construct from |do_QueryInterface(expr)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsQueryInterface aQI)
+    : NSCAP_CTOR_BASE(nullptr)
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_qi(aQI, NS_GET_TEMPLATE_IID(T));
+  }
+
+  // Construct from |do_QueryInterface(expr, &rv)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsQueryInterfaceWithError& aQI)
+    : NSCAP_CTOR_BASE(nullptr)
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_qi_with_error(aQI, NS_GET_TEMPLATE_IID(T));
+  }
+
+  // Construct from |do_GetService(cid_expr)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByCID aGS)
+    : NSCAP_CTOR_BASE(nullptr)
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_gs_cid(aGS, NS_GET_TEMPLATE_IID(T));
+  }
+
+  // Construct from |do_GetService(cid_expr, &rv)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByCIDWithError& aGS)
+    : NSCAP_CTOR_BASE(nullptr)
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_gs_cid_with_error(aGS, NS_GET_TEMPLATE_IID(T));
+  }
+
+  // Construct from |do_GetService(contractid_expr)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByContractID aGS)
+    : NSCAP_CTOR_BASE(nullptr)
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_gs_contractid(aGS, NS_GET_TEMPLATE_IID(T));
+  }
+
+  // Construct from |do_GetService(contractid_expr, &rv)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByContractIDWithError& aGS)
+    : NSCAP_CTOR_BASE(nullptr)
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_gs_contractid_with_error(aGS, NS_GET_TEMPLATE_IID(T));
+  }
+
+  // And finally, anything else we might need to construct from can exploit the
+  // nsCOMPtr_helper facility.
+  MOZ_IMPLICIT nsCOMPtr(const nsCOMPtr_helper& aHelper)
+    : NSCAP_CTOR_BASE(nullptr)
+  {
+    assert_validity();
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_helper(aHelper, NS_GET_TEMPLATE_IID(T));
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+  }
+
+  // Defined in OwningNonNull.h
+  template<class U>
+  MOZ_IMPLICIT nsCOMPtr(const mozilla::OwningNonNull<U>& aOther);
+
+
+  // Assignment operators
+
+  nsCOMPtr<T>& operator=(const nsCOMPtr<T>& aRhs)
+  {
+    assign_with_AddRef(aRhs.mRawPtr);
+    return *this;
+  }
+
+  nsCOMPtr<T>& operator=(T* aRhs)
+  {
+    assign_with_AddRef(aRhs);
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+    return *this;
+  }
+
+  nsCOMPtr<T>& operator=(decltype(nullptr))
+  {
+    assign_assuming_AddRef(nullptr);
+    return *this;
+  }
+
+  // Assign from |already_AddRefed|.
+  template<typename U>
+  nsCOMPtr<T>& operator=(already_AddRefed<U>& aRhs)
+  {
+    // Make sure that U actually inherits from T
+    static_assert(mozilla::IsBaseOf<T, U>::value,
+                  "U is not a subclass of T");
+    assign_assuming_AddRef(static_cast<T*>(aRhs.take()));
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+    return *this;
+  }
+
+  // Assign from |otherComPtr.forget()|.
+  template<typename U>
+  nsCOMPtr<T>& operator=(already_AddRefed<U>&& aRhs)
+  {
+    // Make sure that U actually inherits from T
+    static_assert(mozilla::IsBaseOf<T, U>::value,
+                  "U is not a subclass of T");
+    assign_assuming_AddRef(static_cast<T*>(aRhs.take()));
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+    return *this;
+  }
+
+  // Assign from |do_QueryInterface(expr)|.
+  nsCOMPtr<T>& operator=(const nsQueryInterface aRhs)
+  {
+    assign_from_qi(aRhs, NS_GET_TEMPLATE_IID(T));
+    return *this;
+  }
+
+  // Assign from |do_QueryInterface(expr, &rv)|.
+  nsCOMPtr<T>& operator=(const nsQueryInterfaceWithError& aRhs)
+  {
+    assign_from_qi_with_error(aRhs, NS_GET_TEMPLATE_IID(T));
+    return *this;
+  }
+
+  // Assign from |do_GetService(cid_expr)|.
+  nsCOMPtr<T>& operator=(const nsGetServiceByCID aRhs)
+  {
+    assign_from_gs_cid(aRhs, NS_GET_TEMPLATE_IID(T));
+    return *this;
+  }
+
+  // Assign from |do_GetService(cid_expr, &rv)|.
+  nsCOMPtr<T>& operator=(const nsGetServiceByCIDWithError& aRhs)
+  {
+    assign_from_gs_cid_with_error(aRhs, NS_GET_TEMPLATE_IID(T));
+    return *this;
+  }
+
+  // Assign from |do_GetService(contractid_expr)|.
+  nsCOMPtr<T>& operator=(const nsGetServiceByContractID aRhs)
+  {
+    assign_from_gs_contractid(aRhs, NS_GET_TEMPLATE_IID(T));
+    return *this;
+  }
+
+  // Assign from |do_GetService(contractid_expr, &rv)|.
+  nsCOMPtr<T>& operator=(const nsGetServiceByContractIDWithError& aRhs)
+  {
+    assign_from_gs_contractid_with_error(aRhs, NS_GET_TEMPLATE_IID(T));
+    return *this;
+  }
+
+  // And finally, anything else we might need to assign from can exploit the
+  // nsCOMPtr_helper facility.
+  nsCOMPtr<T>& operator=(const nsCOMPtr_helper& aRhs)
+  {
+    assign_from_helper(aRhs, NS_GET_TEMPLATE_IID(T));
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+    return *this;
+  }
+
+  // Defined in OwningNonNull.h
+  template<class U>
+  nsCOMPtr<T>& operator=(const mozilla::OwningNonNull<U>& aOther);
+
+  // Exchange ownership with |aRhs|; can save a pair of refcount operations.
+  void swap(nsCOMPtr<T>& aRhs)
+  {
+#ifdef NSCAP_FEATURE_USE_BASE
+    nsISupports* temp = aRhs.mRawPtr;
+#else
+    T* temp = aRhs.mRawPtr;
+#endif
+    NSCAP_LOG_ASSIGNMENT(&aRhs, mRawPtr);
+    NSCAP_LOG_ASSIGNMENT(this, temp);
+    NSCAP_LOG_RELEASE(this, mRawPtr);
+    NSCAP_LOG_RELEASE(&aRhs, temp);
+    aRhs.mRawPtr = mRawPtr;
+    mRawPtr = temp;
+    // |aRhs| maintains the same invariants, so we don't need to |NSCAP_ASSERT_NO_QUERY_NEEDED|
+  }
+
+  // Exchange ownership with |aRhs|; can save a pair of refcount operations.
+  void swap(T*& aRhs)
+  {
+#ifdef NSCAP_FEATURE_USE_BASE
+    nsISupports* temp = aRhs;
+#else
+    T* temp = aRhs;
+#endif
+    NSCAP_LOG_ASSIGNMENT(this, temp);
+    NSCAP_LOG_RELEASE(this, mRawPtr);
+    aRhs = reinterpret_cast<T*>(mRawPtr);
+    mRawPtr = temp;
+    NSCAP_ASSERT_NO_QUERY_NEEDED();
+  }
+
+
+  // Other pointer operators
+
+  // Return the value of mRawPtr and null out mRawPtr. Useful for
+  // already_AddRefed return values.
+  already_AddRefed<T> forget()
+  {
+    T* temp = nullptr;
+    swap(temp);
+    return already_AddRefed<T>(temp);
+  }
+
+  // Set the target of aRhs to the value of mRawPtr and null out mRawPtr.
+  // Useful to avoid unnecessary AddRef/Release pairs with "out" parameters
+  // where aRhs bay be a T** or an I** where I is a base class of T.
+  template<typename I>
+  void forget(I** aRhs)
+  {
+    NS_ASSERTION(aRhs, "Null pointer passed to forget!");
+    NSCAP_LOG_RELEASE(this, mRawPtr);
+    *aRhs = get();
+    mRawPtr = nullptr;
+  }
+
+  // Prefer the implicit conversion provided automatically by
+  // |operator T*() const|. Use |get()| to resolve ambiguity or to get a
+  // castable pointer.
+  T* get() const { return reinterpret_cast<T*>(mRawPtr); }
+
+  // Makes an nsCOMPtr act like its underlying raw pointer type whenever it is
+  // used in a context where a raw pointer is expected. It is this operator
+  // that makes an nsCOMPtr substitutable for a raw pointer.
+  //
+  // Prefer the implicit use of this operator to calling |get()|, except where
+  // necessary to resolve ambiguity.
+  operator T*() const
+#ifdef MOZ_HAVE_REF_QUALIFIERS
+  &
+#endif
+  { return get(); }
+
+#ifdef MOZ_HAVE_REF_QUALIFIERS
+  // Don't allow implicit conversion of temporary nsCOMPtr to raw pointer,
+  // because the refcount might be one and the pointer will immediately become
+  // invalid.
+  operator T*() const && = delete;
+
+  // Needed to avoid the deleted operator above
+  explicit operator bool() const { return !!mRawPtr; }
+#endif
+
+  T* operator->() const MOZ_NO_ADDREF_RELEASE_ON_RETURN
+  {
+    MOZ_ASSERT(mRawPtr != nullptr,
+               "You can't dereference a NULL nsCOMPtr with operator->().");
+    return get();
+  }
+
+  // These are not intended to be used by clients. See |address_of| below.
+  nsCOMPtr<T>* get_address() { return this; }
+  const nsCOMPtr<T>* get_address() const { return this; }
+
+public:
+  T& operator*() const
+  {
+    MOZ_ASSERT(mRawPtr != nullptr,
+               "You can't dereference a NULL nsCOMPtr with operator*().");
+    return *get();
+  }
+
+  T** StartAssignment()
+  {
+#ifndef NSCAP_FEATURE_INLINE_STARTASSIGNMENT
+    return reinterpret_cast<T**>(begin_assignment());
+#else
+    assign_assuming_AddRef(nullptr);
+    return reinterpret_cast<T**>(&mRawPtr);
+#endif
+  }
+};
+
+
+/*
+ * Specializing nsCOMPtr for nsISupports allows us to use nsCOMPtr<nsISupports>
+ * the same way people use nsISupports* and void*, i.e., as a `catch-all'
+ * pointing to any valid [XP]COM interface. Otherwise, an nsCOMPtr<nsISupports>
+ * would only be able to point to the single [XP]COM-correct nsISupports
+ * instance within an object; extra querying ensues. Clients need to be able to
+ * pass around arbitrary interface pointers, without hassles, through
+ * intermediary code that doesn't know the exact type.
+ */
+template<>
+class nsCOMPtr<nsISupports>
+  : private nsCOMPtr_base
+{
+public:
+  typedef nsISupports element_type;
+
+  // Constructors
+
+  nsCOMPtr()
+    : nsCOMPtr_base(nullptr)
+  {
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+  }
+
+  MOZ_IMPLICIT nsCOMPtr(decltype(nullptr))
+    : nsCOMPtr_base(nullptr)
+  {
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+  }
+
+  nsCOMPtr(const nsCOMPtr<nsISupports>& aSmartPtr)
+    : nsCOMPtr_base(aSmartPtr.mRawPtr)
+  {
+    if (mRawPtr) {
+      NSCAP_ADDREF(this, mRawPtr);
+    }
+    NSCAP_LOG_ASSIGNMENT(this, aSmartPtr.mRawPtr);
+  }
+
+  MOZ_IMPLICIT nsCOMPtr(nsISupports* aRawPtr)
+    : nsCOMPtr_base(aRawPtr)
+  {
+    if (mRawPtr) {
+      NSCAP_ADDREF(this, mRawPtr);
+    }
+    NSCAP_LOG_ASSIGNMENT(this, aRawPtr);
+  }
+
+  // Construct from |already_AddRefed|.
+  MOZ_IMPLICIT nsCOMPtr(already_AddRefed<nsISupports>& aSmartPtr)
+    : nsCOMPtr_base(aSmartPtr.take())
+  {
+    NSCAP_LOG_ASSIGNMENT(this, mRawPtr);
+  }
+
+  // Construct from |otherComPtr.forget()|.
+  MOZ_IMPLICIT nsCOMPtr(already_AddRefed<nsISupports>&& aSmartPtr)
+    : nsCOMPtr_base(aSmartPtr.take())
+  {
+    NSCAP_LOG_ASSIGNMENT(this, mRawPtr);
+  }
+
+  // Construct from |do_QueryInterface(expr)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsQueryInterface aQI)
+    : nsCOMPtr_base(nullptr)
+  {
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_qi(aQI, NS_GET_IID(nsISupports));
+  }
+
+  // Construct from |do_QueryInterface(expr, &rv)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsQueryInterfaceWithError& aQI)
+    : nsCOMPtr_base(nullptr)
+  {
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_qi_with_error(aQI, NS_GET_IID(nsISupports));
+  }
+
+  // Construct from |do_GetService(cid_expr)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByCID aGS)
+    : nsCOMPtr_base(nullptr)
+  {
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_gs_cid(aGS, NS_GET_IID(nsISupports));
+  }
+
+  // Construct from |do_GetService(cid_expr, &rv)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByCIDWithError& aGS)
+    : nsCOMPtr_base(nullptr)
+  {
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_gs_cid_with_error(aGS, NS_GET_IID(nsISupports));
+  }
+
+  // Construct from |do_GetService(contractid_expr)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByContractID aGS)
+    : nsCOMPtr_base(nullptr)
+  {
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_gs_contractid(aGS, NS_GET_IID(nsISupports));
+  }
+
+  // Construct from |do_GetService(contractid_expr, &rv)|.
+  MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByContractIDWithError& aGS)
+    : nsCOMPtr_base(nullptr)
+  {
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_gs_contractid_with_error(aGS, NS_GET_IID(nsISupports));
+  }
+
+  // And finally, anything else we might need to construct from can exploit
+  // the |nsCOMPtr_helper| facility
+  MOZ_IMPLICIT nsCOMPtr(const nsCOMPtr_helper& aHelper)
+    : nsCOMPtr_base(nullptr)
+  {
+    NSCAP_LOG_ASSIGNMENT(this, nullptr);
+    assign_from_helper(aHelper, NS_GET_IID(nsISupports));
+  }
+
+
+  // Assignment operators
+
+  nsCOMPtr<nsISupports>& operator=(const nsCOMPtr<nsISupports>& aRhs)
+  {
+    assign_with_AddRef(aRhs.mRawPtr);
+    return *this;
+  }
+
+  nsCOMPtr<nsISupports>& operator=(nsISupports* aRhs)
+  {
+    assign_with_AddRef(aRhs);
+    return *this;
+  }
+
+  nsCOMPtr<nsISupports>& operator=(decltype(nullptr))
+  {
+    assign_assuming_AddRef(nullptr);
+    return *this;
+  }
+
+  // Assign from |already_AddRefed|.
+  nsCOMPtr<nsISupports>& operator=(already_AddRefed<nsISupports>& aRhs)
+  {
+    assign_assuming_AddRef(aRhs.take());
+    return *this;
+  }
+
+  // Assign from |otherComPtr.forget()|.
+  nsCOMPtr<nsISupports>& operator=(already_AddRefed<nsISupports>&& aRhs)
+  {
+    assign_assuming_AddRef(aRhs.take());
+    return *this;
+  }
+
+  // Assign from |do_QueryInterface(expr)|.
+  nsCOMPtr<nsISupports>& operator=(const nsQueryInterface aRhs)
+  {
+    assign_from_qi(aRhs, NS_GET_IID(nsISupports));
+    return *this;
+  }
+
+  // Assign from |do_QueryInterface(expr, &rv)|.
+  nsCOMPtr<nsISupports>& operator=(const nsQueryInterfaceWithError& aRhs)
+  {
+    assign_from_qi_with_error(aRhs, NS_GET_IID(nsISupports));
+    return *this;
+  }
+
+  // Assign from |do_GetService(cid_expr)|.
+  nsCOMPtr<nsISupports>& operator=(const nsGetServiceByCID aRhs)
+  {
+    assign_from_gs_cid(aRhs, NS_GET_IID(nsISupports));
+    return *this;
+  }
+
+  // Assign from |do_GetService(cid_expr, &rv)|.
+  nsCOMPtr<nsISupports>& operator=(const nsGetServiceByCIDWithError& aRhs)
+  {
+    assign_from_gs_cid_with_error(aRhs, NS_GET_IID(nsISupports));
+    return *this;
+  }
+
+  // Assign from |do_GetService(contractid_expr)|.
+  nsCOMPtr<nsISupports>& operator=(const nsGetServiceByContractID aRhs)
+  {
+    assign_from_gs_contractid(aRhs, NS_GET_IID(nsISupports));
+    return *this;
+  }
+
+  // Assign from |do_GetService(contractid_expr, &rv)|.
+  nsCOMPtr<nsISupports>& operator=(const nsGetServiceByContractIDWithError& aRhs)
+  {
+    assign_from_gs_contractid_with_error(aRhs, NS_GET_IID(nsISupports));
+    return *this;
+  }
+
+  // And finally, anything else we might need to assign from can exploit the
+  // nsCOMPtr_helper facility
+  nsCOMPtr<nsISupports>& operator=(const nsCOMPtr_helper& aRhs)
+  {
+    assign_from_helper(aRhs, NS_GET_IID(nsISupports));
+    return *this;
+  }
+
+  // Exchange ownership with |aRhs|; can save a pair of refcount operations.
+  void swap(nsCOMPtr<nsISupports>& aRhs)
+  {
+    nsISupports* temp = aRhs.mRawPtr;
+    NSCAP_LOG_ASSIGNMENT(&aRhs, mRawPtr);
+    NSCAP_LOG_ASSIGNMENT(this, temp);
+    NSCAP_LOG_RELEASE(this, mRawPtr);
+    NSCAP_LOG_RELEASE(&aRhs, temp);
+    aRhs.mRawPtr = mRawPtr;
+    mRawPtr = temp;
+  }
+
+  // Exchange ownership with |aRhs|; can save a pair of refcount operations.
+  void swap(nsISupports*& aRhs)
+  {
+    nsISupports* temp = aRhs;
+    NSCAP_LOG_ASSIGNMENT(this, temp);
+    NSCAP_LOG_RELEASE(this, mRawPtr);
+    aRhs = mRawPtr;
+    mRawPtr = temp;
+  }
+
+  // Return the value of mRawPtr and null out mRawPtr. Useful for
+  // already_AddRefed return values.
+  already_AddRefed<nsISupports> forget()
+  {
+    nsISupports* temp = nullptr;
+    swap(temp);
+    return already_AddRefed<nsISupports>(temp);
+  }
+
+  // Set the target of aRhs to the value of mRawPtr and null out mRawPtr.
+  // Useful to avoid unnecessary AddRef/Release pairs with "out"
+  // parameters.
+  void forget(nsISupports** aRhs)
+  {
+    NS_ASSERTION(aRhs, "Null pointer passed to forget!");
+    *aRhs = nullptr;
+    swap(*aRhs);
+  }
+
+  // Other pointer operators
+
+  // Prefer the implicit conversion provided automatically by
+  // |operator nsISupports*() const|. Use |get()| to resolve ambiguity or to
+  // get a castable pointer.
+  nsISupports* get() const { return reinterpret_cast<nsISupports*>(mRawPtr); }
+
+  // Makes an nsCOMPtr act like its underlying raw pointer type whenever it is
+  // used in a context where a raw pointer is expected. It is this operator
+  // that makes an nsCOMPtr substitutable for a raw pointer.
+  //
+  // Prefer the implicit use of this operator to calling |get()|, except where
+  // necessary to resolve ambiguity/
+  operator nsISupports* () const { return get(); }
+
+  nsISupports* operator->() const MOZ_NO_ADDREF_RELEASE_ON_RETURN
+  {
+    MOZ_ASSERT(mRawPtr != nullptr,
+               "You can't dereference a NULL nsCOMPtr with operator->().");
+    return get();
+  }
+
+  // These are not intended to be used by clients. See |address_of| below.
+  nsCOMPtr<nsISupports>* get_address() { return this; }
+  const nsCOMPtr<nsISupports>* get_address() const { return this; }
+
+public:
+
+  nsISupports& operator*() const
+  {
+    MOZ_ASSERT(mRawPtr != nullptr,
+               "You can't dereference a NULL nsCOMPtr with operator*().");
+    return *get();
+  }
+
+  nsISupports** StartAssignment()
+  {
+#ifndef NSCAP_FEATURE_INLINE_STARTASSIGNMENT
+    return reinterpret_cast<nsISupports**>(begin_assignment());
+#else
+    assign_assuming_AddRef(nullptr);
+    return reinterpret_cast<nsISupports**>(&mRawPtr);
+#endif
+  }
+};
+
+template<typename T>
+inline void
+ImplCycleCollectionUnlink(nsCOMPtr<T>& aField)
+{
+  aField = nullptr;
+}
+
+template<typename T>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            nsCOMPtr<T>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  CycleCollectionNoteChild(aCallback, aField.get(), aName, aFlags);
+}
+
+#ifndef NSCAP_FEATURE_USE_BASE
+template<class T>
+void
+nsCOMPtr<T>::assign_with_AddRef(nsISupports* aRawPtr)
+{
+  if (aRawPtr) {
+    NSCAP_ADDREF(this, aRawPtr);
+  }
+  assign_assuming_AddRef(reinterpret_cast<T*>(aRawPtr));
+}
+
+template<class T>
+void
+nsCOMPtr<T>::assign_from_qi(const nsQueryInterface aQI, const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aQI(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<T*>(newRawPtr));
+}
+
+template<class T>
+void
+nsCOMPtr<T>::assign_from_qi_with_error(const nsQueryInterfaceWithError& aQI,
+                                       const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aQI(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<T*>(newRawPtr));
+}
+
+template<class T>
+void
+nsCOMPtr<T>::assign_from_gs_cid(const nsGetServiceByCID aGS, const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aGS(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<T*>(newRawPtr));
+}
+
+template<class T>
+void
+nsCOMPtr<T>::assign_from_gs_cid_with_error(const nsGetServiceByCIDWithError& aGS,
+                                           const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aGS(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<T*>(newRawPtr));
+}
+
+template<class T>
+void
+nsCOMPtr<T>::assign_from_gs_contractid(const nsGetServiceByContractID aGS,
+                                       const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aGS(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<T*>(newRawPtr));
+}
+
+template<class T>
+void
+nsCOMPtr<T>::assign_from_gs_contractid_with_error(
+    const nsGetServiceByContractIDWithError& aGS, const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aGS(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<T*>(newRawPtr));
+}
+
+template<class T>
+void
+nsCOMPtr<T>::assign_from_helper(const nsCOMPtr_helper& helper, const nsIID& aIID)
+{
+  void* newRawPtr;
+  if (NS_FAILED(helper(aIID, &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<T*>(newRawPtr));
+}
+
+template<class T>
+void**
+nsCOMPtr<T>::begin_assignment()
+{
+  assign_assuming_AddRef(nullptr);
+  union
+  {
+    T** mT;
+    void** mVoid;
+  } result;
+  result.mT = &mRawPtr;
+  return result.mVoid;
+}
+#endif
+
+template<class T>
+inline nsCOMPtr<T>*
+address_of(nsCOMPtr<T>& aPtr)
+{
+  return aPtr.get_address();
+}
+
+template<class T>
+inline const nsCOMPtr<T>*
+address_of(const nsCOMPtr<T>& aPtr)
+{
+  return aPtr.get_address();
+}
+
+/**
+ * This class is designed to be used for anonymous temporary objects in the
+ * argument list of calls that return COM interface pointers, e.g.,
+ *
+ *   nsCOMPtr<IFoo> fooP;
+ *   ...->QueryInterface(iid, getter_AddRefs(fooP))
+ *
+ * DO NOT USE THIS TYPE DIRECTLY IN YOUR CODE. Use |getter_AddRefs()| instead.
+ *
+ * When initialized with a |nsCOMPtr|, as in the example above, it returns
+ * a |void**|, a |T**|, or an |nsISupports**| as needed, that the outer call
+ * (|QueryInterface| in this case) can fill in.
+ *
+ * This type should be a nested class inside |nsCOMPtr<T>|.
+ */
+template<class T>
+class nsGetterAddRefs
+{
+public:
+  explicit nsGetterAddRefs(nsCOMPtr<T>& aSmartPtr)
+    : mTargetSmartPtr(aSmartPtr)
+  {
+  }
+
+#if defined(NSCAP_FEATURE_TEST_DONTQUERY_CASES) || defined(NSCAP_LOG_EXTERNAL_ASSIGNMENT)
+  ~nsGetterAddRefs()
+  {
+#ifdef NSCAP_LOG_EXTERNAL_ASSIGNMENT
+    NSCAP_LOG_ASSIGNMENT(reinterpret_cast<void*>(address_of(mTargetSmartPtr)),
+                         mTargetSmartPtr.get());
+#endif
+
+#ifdef NSCAP_FEATURE_TEST_DONTQUERY_CASES
+    mTargetSmartPtr.Assert_NoQueryNeeded();
+#endif
+  }
+#endif
+
+  operator void**()
+  {
+    return reinterpret_cast<void**>(mTargetSmartPtr.StartAssignment());
+  }
+
+  operator T**() { return mTargetSmartPtr.StartAssignment(); }
+  T*& operator*() { return *(mTargetSmartPtr.StartAssignment()); }
+
+private:
+  nsCOMPtr<T>& mTargetSmartPtr;
+};
+
+
+template<>
+class nsGetterAddRefs<nsISupports>
+{
+public:
+  explicit nsGetterAddRefs(nsCOMPtr<nsISupports>& aSmartPtr)
+    : mTargetSmartPtr(aSmartPtr)
+  {
+  }
+
+#ifdef NSCAP_LOG_EXTERNAL_ASSIGNMENT
+  ~nsGetterAddRefs()
+  {
+    NSCAP_LOG_ASSIGNMENT(reinterpret_cast<void*>(address_of(mTargetSmartPtr)),
+                         mTargetSmartPtr.get());
+  }
+#endif
+
+  operator void**()
+  {
+    return reinterpret_cast<void**>(mTargetSmartPtr.StartAssignment());
+  }
+
+  operator nsISupports**() { return mTargetSmartPtr.StartAssignment(); }
+  nsISupports*& operator*() { return *(mTargetSmartPtr.StartAssignment()); }
+
+private:
+  nsCOMPtr<nsISupports>& mTargetSmartPtr;
+};
+
+template<class T>
+inline nsGetterAddRefs<T>
+getter_AddRefs(nsCOMPtr<T>& aSmartPtr)
+{
+  return nsGetterAddRefs<T>(aSmartPtr);
+}
+
+template<class T, class DestinationType>
+inline nsresult
+CallQueryInterface(T* aSource, nsGetterAddRefs<DestinationType> aDestination)
+{
+  return CallQueryInterface(aSource,
+                            static_cast<DestinationType**>(aDestination));
+}
+
+
+// Comparing two |nsCOMPtr|s
+
+template<class T, class U>
+inline bool
+operator==(const nsCOMPtr<T>& aLhs, const nsCOMPtr<U>& aRhs)
+{
+  return static_cast<const T*>(aLhs.get()) == static_cast<const U*>(aRhs.get());
+}
+
+
+template<class T, class U>
+inline bool
+operator!=(const nsCOMPtr<T>& aLhs, const nsCOMPtr<U>& aRhs)
+{
+  return static_cast<const T*>(aLhs.get()) != static_cast<const U*>(aRhs.get());
+}
+
+
+// Comparing an |nsCOMPtr| to a raw pointer
+
+template<class T, class U>
+inline bool
+operator==(const nsCOMPtr<T>& aLhs, const U* aRhs)
+{
+  return static_cast<const T*>(aLhs.get()) == aRhs;
+}
+
+template<class T, class U>
+inline bool
+operator==(const U* aLhs, const nsCOMPtr<T>& aRhs)
+{
+  return aLhs == static_cast<const T*>(aRhs.get());
+}
+
+template<class T, class U>
+inline bool
+operator!=(const nsCOMPtr<T>& aLhs, const U* aRhs)
+{
+  return static_cast<const T*>(aLhs.get()) != aRhs;
+}
+
+template<class T, class U>
+inline bool
+operator!=(const U* aLhs, const nsCOMPtr<T>& aRhs)
+{
+  return aLhs != static_cast<const T*>(aRhs.get());
+}
+
+template<class T, class U>
+inline bool
+operator==(const nsCOMPtr<T>& aLhs, U* aRhs)
+{
+  return static_cast<const T*>(aLhs.get()) == const_cast<const U*>(aRhs);
+}
+
+template<class T, class U>
+inline bool
+operator==(U* aLhs, const nsCOMPtr<T>& aRhs)
+{
+  return const_cast<const U*>(aLhs) == static_cast<const T*>(aRhs.get());
+}
+
+template<class T, class U>
+inline bool
+operator!=(const nsCOMPtr<T>& aLhs, U* aRhs)
+{
+  return static_cast<const T*>(aLhs.get()) != const_cast<const U*>(aRhs);
+}
+
+template<class T, class U>
+inline bool
+operator!=(U* aLhs, const nsCOMPtr<T>& aRhs)
+{
+  return const_cast<const U*>(aLhs) != static_cast<const T*>(aRhs.get());
+}
+
+
+
+// Comparing an |nsCOMPtr| to |nullptr|
+
+template<class T>
+inline bool
+operator==(const nsCOMPtr<T>& aLhs, decltype(nullptr))
+{
+  return aLhs.get() == nullptr;
+}
+
+template<class T>
+inline bool
+operator==(decltype(nullptr), const nsCOMPtr<T>& aRhs)
+{
+  return nullptr == aRhs.get();
+}
+
+template<class T>
+inline bool
+operator!=(const nsCOMPtr<T>& aLhs, decltype(nullptr))
+{
+  return aLhs.get() != nullptr;
+}
+
+template<class T>
+inline bool
+operator!=(decltype(nullptr), const nsCOMPtr<T>& aRhs)
+{
+  return nullptr != aRhs.get();
+}
+
+
+// Comparing any two [XP]COM objects for identity
+
+inline bool
+SameCOMIdentity(nsISupports* aLhs, nsISupports* aRhs)
+{
+  return nsCOMPtr<nsISupports>(do_QueryInterface(aLhs)) ==
+    nsCOMPtr<nsISupports>(do_QueryInterface(aRhs));
+}
+
+
+
+template<class SourceType, class DestinationType>
+inline nsresult
+CallQueryInterface(nsCOMPtr<SourceType>& aSourcePtr, DestinationType** aDestPtr)
+{
+  return CallQueryInterface(aSourcePtr.get(), aDestPtr);
+}
+
+template <class T>
+RefPtr<T>::RefPtr(const nsCOMPtr_helper& aHelper)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aHelper(NS_GET_TEMPLATE_IID(T), &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  mRawPtr = static_cast<T*>(newRawPtr);
+}
+
+template <class T>
+RefPtr<T>&
+RefPtr<T>::operator=(const nsCOMPtr_helper& aHelper)
+{
+  void* newRawPtr;
+  if (NS_FAILED(aHelper(NS_GET_TEMPLATE_IID(T), &newRawPtr))) {
+    newRawPtr = nullptr;
+  }
+  assign_assuming_AddRef(static_cast<T*>(newRawPtr));
+  return *this;
+}
+
+
+#endif // !defined(nsCOMPtr_h___)
diff --git a/xpcom/glue/nsCRTGlue.cpp b/xpcom/glue/nsCRTGlue.cpp
new file mode 100644
index 000000000..7a9f6db03
--- /dev/null
+++ b/xpcom/glue/nsCRTGlue.cpp
@@ -0,0 +1,441 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCRTGlue.h"
+#include "nsXPCOM.h"
+#include "nsDebug.h"
+#include "prtime.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdarg.h>
+
+#include "mozilla/Sprintf.h"
+
+#ifdef XP_WIN
+#include <io.h>
+#include <windows.h>
+#include "mozilla/UniquePtr.h"
+#endif
+
+#ifdef ANDROID
+#include <android/log.h>
+#include <unistd.h>
+#endif
+
+using namespace mozilla;
+
+const char*
+NS_strspnp(const char* aDelims, const char* aStr)
+{
+  const char* d;
+  do {
+    for (d = aDelims; *d != '\0'; ++d) {
+      if (*aStr == *d) {
+        ++aStr;
+        break;
+      }
+    }
+  } while (*d);
+
+  return aStr;
+}
+
+char*
+NS_strtok(const char* aDelims, char** aStr)
+{
+  if (!*aStr) {
+    return nullptr;
+  }
+
+  char* ret = (char*)NS_strspnp(aDelims, *aStr);
+
+  if (!*ret) {
+    *aStr = ret;
+    return nullptr;
+  }
+
+  char* i = ret;
+  do {
+    for (const char* d = aDelims; *d != '\0'; ++d) {
+      if (*i == *d) {
+        *i = '\0';
+        *aStr = ++i;
+        return ret;
+      }
+    }
+    ++i;
+  } while (*i);
+
+  *aStr = nullptr;
+  return ret;
+}
+
+uint32_t
+NS_strlen(const char16_t* aString)
+{
+  MOZ_ASSERT(aString);
+  const char16_t* end;
+
+  for (end = aString; *end; ++end) {
+    // empty loop
+  }
+
+  return end - aString;
+}
+
+int
+NS_strcmp(const char16_t* aStrA, const char16_t* aStrB)
+{
+  while (*aStrB) {
+    int r = *aStrA - *aStrB;
+    if (r) {
+      return r;
+    }
+
+    ++aStrA;
+    ++aStrB;
+  }
+
+  return *aStrA != '\0';
+}
+
+int
+NS_strncmp(const char16_t* aStrA, const char16_t* aStrB, size_t aLen)
+{
+  while (aLen && *aStrB) {
+    int r = *aStrA - *aStrB;
+    if (r) {
+      return r;
+    }
+
+    ++aStrA;
+    ++aStrB;
+    --aLen;
+  }
+
+  return aLen ? *aStrA != '\0' : *aStrA - *aStrB;
+}
+
+char16_t*
+NS_strdup(const char16_t* aString)
+{
+  uint32_t len = NS_strlen(aString);
+  return NS_strndup(aString, len);
+}
+
+template<typename CharT>
+CharT*
+NS_strndup(const CharT* aString, uint32_t aLen)
+{
+  auto newBuf = (CharT*)NS_Alloc((aLen + 1) * sizeof(CharT));
+  if (newBuf) {
+    memcpy(newBuf, aString, aLen * sizeof(CharT));
+    newBuf[aLen] = '\0';
+  }
+  return newBuf;
+}
+
+template char16_t* NS_strndup<char16_t>(const char16_t* aString, uint32_t aLen);
+template char* NS_strndup<char>(const char* aString, uint32_t aLen);
+
+char*
+NS_strdup(const char* aString)
+{
+  uint32_t len = strlen(aString);
+  char* str = (char*)NS_Alloc(len + 1);
+  if (str) {
+    memcpy(str, aString, len);
+    str[len] = '\0';
+  }
+  return str;
+}
+
+// This table maps uppercase characters to lower case characters;
+// characters that are neither upper nor lower case are unaffected.
+const unsigned char nsLowerUpperUtils::kUpper2Lower[256] = {
+    0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15,
+   16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
+   32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
+   48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63,
+   64,
+
+    // upper band mapped to lower [A-Z] => [a-z]
+       97, 98, 99,100,101,102,103,104,105,106,107,108,109,110,111,
+  112,113,114,115,116,117,118,119,120,121,122,
+
+                                               91, 92, 93, 94, 95,
+   96, 97, 98, 99,100,101,102,103,104,105,106,107,108,109,110,111,
+  112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,
+  128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,
+  144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,
+  160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,
+  176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,
+  192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,
+  208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,
+  224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,
+  240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255
+};
+
+const unsigned char nsLowerUpperUtils::kLower2Upper[256] = {
+    0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15,
+   16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
+   32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
+   48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63,
+   64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,
+   80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95,
+   96,
+
+    // lower band mapped to upper [a-z] => [A-Z]
+       65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,
+   80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90,
+
+                                              123,124,125,126,127,
+  128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,
+  144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,
+  160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,
+  176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,
+  192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,
+  208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,
+  224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,
+  240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255
+};
+
+bool
+NS_IsUpper(char aChar)
+{
+  return aChar != (char)nsLowerUpperUtils::kUpper2Lower[(unsigned char)aChar];
+}
+
+bool
+NS_IsLower(char aChar)
+{
+  return aChar != (char)nsLowerUpperUtils::kLower2Upper[(unsigned char)aChar];
+}
+
+bool
+NS_IsAscii(char16_t aChar)
+{
+  return (0x0080 > aChar);
+}
+
+bool
+NS_IsAscii(const char16_t* aString)
+{
+  while (*aString) {
+    if (0x0080 <= *aString) {
+      return false;
+    }
+    aString++;
+  }
+  return true;
+}
+
+bool
+NS_IsAscii(const char* aString)
+{
+  while (*aString) {
+    if (0x80 & *aString) {
+      return false;
+    }
+    aString++;
+  }
+  return true;
+}
+
+bool
+NS_IsAscii(const char* aString, uint32_t aLength)
+{
+  const char* end = aString + aLength;
+  while (aString < end) {
+    if (0x80 & *aString) {
+      return false;
+    }
+    ++aString;
+  }
+  return true;
+}
+
+bool
+NS_IsAsciiAlpha(char16_t aChar)
+{
+  return (aChar >= 'A' && aChar <= 'Z') ||
+         (aChar >= 'a' && aChar <= 'z');
+}
+
+bool
+NS_IsAsciiWhitespace(char16_t aChar)
+{
+  return aChar == ' ' ||
+         aChar == '\r' ||
+         aChar == '\n' ||
+         aChar == '\t';
+}
+
+bool
+NS_IsAsciiDigit(char16_t aChar)
+{
+  return aChar >= '0' && aChar <= '9';
+}
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+
+void
+NS_MakeRandomString(char* aBuf, int32_t aBufLen)
+{
+#define TABLE_SIZE 36
+  static const char table[] = {
+    'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
+    'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
+    'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3',
+    '4', '5', '6', '7', '8', '9'
+  };
+
+  // turn PR_Now() into milliseconds since epoch
+  // and salt rand with that.
+  static unsigned int seed = 0;
+  if (seed == 0) {
+    double fpTime = double(PR_Now());
+    seed = (unsigned int)(fpTime * 1e-6 + 0.5); // use 1e-6, granularity of PR_Now() on the mac is seconds
+    srand(seed);
+  }
+
+  int32_t i;
+  for (i = 0; i < aBufLen; ++i) {
+    *aBuf++ = table[rand() % TABLE_SIZE];
+  }
+  *aBuf = 0;
+}
+
+#endif
+
+static StderrCallback sStderrCallback = nullptr;
+
+void
+set_stderr_callback(StderrCallback aCallback)
+{
+  sStderrCallback = aCallback;
+}
+
+#if defined(ANDROID) && !defined(RELEASE_OR_BETA)
+static FILE* sStderrCopy = nullptr;
+
+void
+stderr_to_file(const char* aFmt, va_list aArgs)
+{
+  vfprintf(sStderrCopy, aFmt, aArgs);
+}
+
+void
+copy_stderr_to_file(const char* aFile)
+{
+  if (sStderrCopy) {
+    return;
+  }
+  size_t buflen = strlen(aFile) + 16;
+  char* buf = (char*)malloc(buflen);
+  snprintf(buf, buflen, "%s.%u", aFile, (uint32_t)getpid());
+  sStderrCopy = fopen(buf, "w");
+  free(buf);
+  set_stderr_callback(stderr_to_file);
+}
+#endif
+
+#ifdef HAVE_VA_COPY
+#define VARARGS_ASSIGN(foo, bar)        VA_COPY(foo,bar)
+#elif defined(HAVE_VA_LIST_AS_ARRAY)
+#define VARARGS_ASSIGN(foo, bar)     foo[0] = bar[0]
+#else
+#define VARARGS_ASSIGN(foo, bar)     (foo) = (bar)
+#endif
+
+#if defined(XP_WIN)
+void
+vprintf_stderr(const char* aFmt, va_list aArgs)
+{
+  if (sStderrCallback) {
+    va_list argsCpy;
+    VARARGS_ASSIGN(argsCpy, aArgs);
+    sStderrCallback(aFmt, aArgs);
+    va_end(argsCpy);
+  }
+
+  if (IsDebuggerPresent()) {
+    int lengthNeeded = _vscprintf(aFmt, aArgs);
+    if (lengthNeeded) {
+      lengthNeeded++;
+      auto buf = MakeUnique<char[]>(lengthNeeded);
+      if (buf) {
+        va_list argsCpy;
+        VARARGS_ASSIGN(argsCpy, aArgs);
+        vsnprintf(buf.get(), lengthNeeded, aFmt, argsCpy);
+        buf[lengthNeeded - 1] = '\0';
+        va_end(argsCpy);
+        OutputDebugStringA(buf.get());
+      }
+    }
+  }
+
+  FILE* fp = _fdopen(_dup(2), "a");
+  if (!fp) {
+    return;
+  }
+
+  vfprintf(fp, aFmt, aArgs);
+
+  fclose(fp);
+}
+
+#elif defined(ANDROID)
+void
+vprintf_stderr(const char* aFmt, va_list aArgs)
+{
+  if (sStderrCallback) {
+    va_list argsCpy;
+    VARARGS_ASSIGN(argsCpy, aArgs);
+    sStderrCallback(aFmt, aArgs);
+    va_end(argsCpy);
+  }
+
+  __android_log_vprint(ANDROID_LOG_INFO, "Gecko", aFmt, aArgs);
+}
+#else
+void
+vprintf_stderr(const char* aFmt, va_list aArgs)
+{
+  if (sStderrCallback) {
+    va_list argsCpy;
+    VARARGS_ASSIGN(argsCpy, aArgs);
+    sStderrCallback(aFmt, aArgs);
+    va_end(argsCpy);
+  }
+
+  vfprintf(stderr, aFmt, aArgs);
+}
+#endif
+
+void
+printf_stderr(const char* aFmt, ...)
+{
+  va_list args;
+  va_start(args, aFmt);
+  vprintf_stderr(aFmt, args);
+  va_end(args);
+}
+
+void
+fprintf_stderr(FILE* aFile, const char* aFmt, ...)
+{
+  va_list args;
+  va_start(args, aFmt);
+  if (aFile == stderr) {
+    vprintf_stderr(aFmt, args);
+  } else {
+    vfprintf(aFile, aFmt, args);
+  }
+  va_end(args);
+}
diff --git a/xpcom/glue/nsCRTGlue.h b/xpcom/glue/nsCRTGlue.h
new file mode 100644
index 000000000..8caa1ae27
--- /dev/null
+++ b/xpcom/glue/nsCRTGlue.h
@@ -0,0 +1,147 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCRTGlue_h__
+#define nsCRTGlue_h__
+
+#include "nscore.h"
+
+/**
+ * Scan a string for the first character that is *not* in a set of
+ * delimiters.  If the string is only delimiter characters, the end of the
+ * string is returned.
+ *
+ * @param aDelims The set of delimiters (null-terminated)
+ * @param aStr    The string to search (null-terminated)
+ */
+const char* NS_strspnp(const char* aDelims, const char* aStr);
+
+/**
+ * Tokenize a string. This function is similar to the strtok function in the
+ * C standard library, but it does not use static variables to maintain state
+ * and is therefore thread and reentrancy-safe.
+ *
+ * Any leading delimiters in str are skipped. Then the string is scanned
+ * until an additional delimiter or end-of-string is found. The final
+ * delimiter is set to '\0'.
+ *
+ * @param aDelims The set of delimiters.
+ * @param aStr    The string to search. This is an in-out parameter; it is
+ *                reset to the end of the found token + 1, or to the
+ *                end-of-string if there are no more tokens.
+ * @return        The token. If no token is found (the string is only
+ *                delimiter characters), nullptr is returned.
+ */
+char* NS_strtok(const char* aDelims, char** aStr);
+
+/**
+ * "strlen" for char16_t strings
+ */
+uint32_t NS_strlen(const char16_t* aString);
+
+/**
+ * "strcmp" for char16_t strings
+ */
+int NS_strcmp(const char16_t* aStrA, const char16_t* aStrB);
+
+/**
+ * "strncmp" for char16_t strings
+ */
+int NS_strncmp(const char16_t* aStrA, const char16_t* aStrB, size_t aLen);
+
+/**
+ * "strdup" for char16_t strings, uses the NS_Alloc allocator.
+ */
+char16_t* NS_strdup(const char16_t* aString);
+
+/**
+ * "strdup", but using the NS_Alloc allocator.
+ */
+char* NS_strdup(const char* aString);
+
+/**
+ * strndup for char16_t or char strings (normal strndup is not available on
+ * windows). This function will ensure that the new string is
+ * null-terminated. Uses the NS_Alloc allocator.
+ *
+ * CharT may be either char16_t or char.
+ */
+template<typename CharT>
+CharT* NS_strndup(const CharT* aString, uint32_t aLen);
+
+// The following case-conversion methods only deal in the ascii repertoire
+// A-Z and a-z
+
+// semi-private data declarations... don't use these directly.
+class nsLowerUpperUtils
+{
+public:
+  static const unsigned char kLower2Upper[256];
+  static const unsigned char kUpper2Lower[256];
+};
+
+inline char
+NS_ToUpper(char aChar)
+{
+  return (char)nsLowerUpperUtils::kLower2Upper[(unsigned char)aChar];
+}
+
+inline char
+NS_ToLower(char aChar)
+{
+  return (char)nsLowerUpperUtils::kUpper2Lower[(unsigned char)aChar];
+}
+
+bool NS_IsUpper(char aChar);
+bool NS_IsLower(char aChar);
+
+bool NS_IsAscii(char16_t aChar);
+bool NS_IsAscii(const char16_t* aString);
+bool NS_IsAsciiAlpha(char16_t aChar);
+bool NS_IsAsciiDigit(char16_t aChar);
+bool NS_IsAsciiWhitespace(char16_t aChar);
+bool NS_IsAscii(const char* aString);
+bool NS_IsAscii(const char* aString, uint32_t aLength);
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+void NS_MakeRandomString(char* aBuf, int32_t aBufLen);
+#endif
+
+#define FF '\f'
+#define TAB '\t'
+
+#define CRSTR "\015"
+#define LFSTR "\012"
+#define CRLF "\015\012"     /* A CR LF equivalent string */
+
+// We use the most restrictive filesystem as our default set of illegal filename
+// characters. This is currently Windows.
+#define OS_FILE_ILLEGAL_CHARACTERS "/:*?\"<>|"
+// We also provide a list of all known file path separators for all filesystems.
+// This can be used in replacement of FILE_PATH_SEPARATOR when you need to
+// identify or replace all known path separators.
+#define KNOWN_PATH_SEPARATORS "\\/"
+
+#if defined(XP_MACOSX)
+  #define FILE_PATH_SEPARATOR        "/"
+#elif defined(XP_WIN)
+  #define FILE_PATH_SEPARATOR        "\\"
+#elif defined(XP_UNIX)
+  #define FILE_PATH_SEPARATOR        "/"
+#else
+  #error need_to_define_your_file_path_separator_and_maybe_illegal_characters
+#endif
+
+// Not all these control characters are illegal in all OSs, but we don't really
+// want them appearing in filenames
+#define CONTROL_CHARACTERS     "\001\002\003\004\005\006\007" \
+                           "\010\011\012\013\014\015\016\017" \
+                           "\020\021\022\023\024\025\026\027" \
+                           "\030\031\032\033\034\035\036\037"
+
+#define FILE_ILLEGAL_CHARACTERS CONTROL_CHARACTERS OS_FILE_ILLEGAL_CHARACTERS
+
+#endif // nsCRTGlue_h__
diff --git a/xpcom/glue/nsCategoryCache.cpp b/xpcom/glue/nsCategoryCache.cpp
new file mode 100644
index 000000000..30501b8e3
--- /dev/null
+++ b/xpcom/glue/nsCategoryCache.cpp
@@ -0,0 +1,149 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIObserverService.h"
+#include "mozilla/Services.h"
+#include "nsISupportsPrimitives.h"
+#include "nsIStringEnumerator.h"
+
+#include "nsXPCOMCID.h"
+
+#include "nsCategoryCache.h"
+
+nsCategoryObserver::nsCategoryObserver(const char* aCategory)
+  : mCategory(aCategory)
+  , mObserversRemoved(false)
+{
+  // First, enumerate the currently existing entries
+  nsCOMPtr<nsICategoryManager> catMan =
+    do_GetService(NS_CATEGORYMANAGER_CONTRACTID);
+  if (!catMan) {
+    return;
+  }
+
+  nsCOMPtr<nsISimpleEnumerator> enumerator;
+  nsresult rv = catMan->EnumerateCategory(aCategory,
+                                          getter_AddRefs(enumerator));
+  if (NS_FAILED(rv)) {
+    return;
+  }
+
+  nsCOMPtr<nsIUTF8StringEnumerator> strings = do_QueryInterface(enumerator);
+  MOZ_ASSERT(strings);
+
+  bool more;
+  while (NS_SUCCEEDED(strings->HasMore(&more)) && more) {
+    nsAutoCString entryName;
+    strings->GetNext(entryName);
+
+    nsCString entryValue;
+    rv = catMan->GetCategoryEntry(aCategory,
+                                  entryName.get(),
+                                  getter_Copies(entryValue));
+    if (NS_SUCCEEDED(rv)) {
+      nsCOMPtr<nsISupports> service = do_GetService(entryValue.get());
+      if (service) {
+        mHash.Put(entryName, service);
+      }
+    }
+  }
+
+  // Now, listen for changes
+  nsCOMPtr<nsIObserverService> serv =
+    mozilla::services::GetObserverService();
+  if (serv) {
+    serv->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID, false);
+    serv->AddObserver(this, NS_XPCOM_CATEGORY_ENTRY_ADDED_OBSERVER_ID, false);
+    serv->AddObserver(this, NS_XPCOM_CATEGORY_ENTRY_REMOVED_OBSERVER_ID, false);
+    serv->AddObserver(this, NS_XPCOM_CATEGORY_CLEARED_OBSERVER_ID, false);
+  }
+}
+
+nsCategoryObserver::~nsCategoryObserver()
+{
+}
+
+NS_IMPL_ISUPPORTS(nsCategoryObserver, nsIObserver)
+
+void
+nsCategoryObserver::ListenerDied()
+{
+  RemoveObservers();
+}
+
+void
+nsCategoryObserver::RemoveObservers()
+{
+  if (mObserversRemoved) {
+    return;
+  }
+
+  mObserversRemoved = true;
+  nsCOMPtr<nsIObserverService> obsSvc =
+    mozilla::services::GetObserverService();
+  if (obsSvc) {
+    obsSvc->RemoveObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID);
+    obsSvc->RemoveObserver(this, NS_XPCOM_CATEGORY_ENTRY_ADDED_OBSERVER_ID);
+    obsSvc->RemoveObserver(this, NS_XPCOM_CATEGORY_ENTRY_REMOVED_OBSERVER_ID);
+    obsSvc->RemoveObserver(this, NS_XPCOM_CATEGORY_CLEARED_OBSERVER_ID);
+  }
+}
+
+NS_IMETHODIMP
+nsCategoryObserver::Observe(nsISupports* aSubject, const char* aTopic,
+                            const char16_t* aData)
+{
+  if (strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID) == 0) {
+    mHash.Clear();
+    RemoveObservers();
+
+    return NS_OK;
+  }
+
+  if (!aData ||
+      !nsDependentString(aData).Equals(NS_ConvertASCIItoUTF16(mCategory))) {
+    return NS_OK;
+  }
+
+  nsAutoCString str;
+  nsCOMPtr<nsISupportsCString> strWrapper(do_QueryInterface(aSubject));
+  if (strWrapper) {
+    strWrapper->GetData(str);
+  }
+
+  if (strcmp(aTopic, NS_XPCOM_CATEGORY_ENTRY_ADDED_OBSERVER_ID) == 0) {
+    // We may get an add notification even when we already have an entry. This
+    // is due to the notification happening asynchronously, so if the entry gets
+    // added and an nsCategoryObserver gets instantiated before events get
+    // processed, we'd get the notification for an existing entry.
+    // Do nothing in that case.
+    if (mHash.GetWeak(str)) {
+      return NS_OK;
+    }
+
+    nsCOMPtr<nsICategoryManager> catMan =
+      do_GetService(NS_CATEGORYMANAGER_CONTRACTID);
+    if (!catMan) {
+      return NS_OK;
+    }
+
+    nsCString entryValue;
+    catMan->GetCategoryEntry(mCategory.get(),
+                             str.get(),
+                             getter_Copies(entryValue));
+
+    nsCOMPtr<nsISupports> service = do_GetService(entryValue.get());
+
+    if (service) {
+      mHash.Put(str, service);
+    }
+  } else if (strcmp(aTopic, NS_XPCOM_CATEGORY_ENTRY_REMOVED_OBSERVER_ID) == 0) {
+    mHash.Remove(str);
+  } else if (strcmp(aTopic, NS_XPCOM_CATEGORY_CLEARED_OBSERVER_ID) == 0) {
+    mHash.Clear();
+  }
+  return NS_OK;
+}
diff --git a/xpcom/glue/nsCategoryCache.h b/xpcom/glue/nsCategoryCache.h
new file mode 100644
index 000000000..023aa7a75
--- /dev/null
+++ b/xpcom/glue/nsCategoryCache.h
@@ -0,0 +1,95 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCategoryCache_h_
+#define nsCategoryCache_h_
+
+#include "mozilla/Attributes.h"
+
+#include "nsICategoryManager.h"
+#include "nsIObserver.h"
+#include "nsISimpleEnumerator.h"
+#include "nsISupportsPrimitives.h"
+
+#include "nsServiceManagerUtils.h"
+
+#include "nsAutoPtr.h"
+#include "nsCOMArray.h"
+#include "nsInterfaceHashtable.h"
+
+#include "nsXPCOM.h"
+
+class nsCategoryObserver final : public nsIObserver
+{
+  ~nsCategoryObserver();
+
+public:
+  explicit nsCategoryObserver(const char* aCategory);
+
+  void ListenerDied();
+  nsInterfaceHashtable<nsCStringHashKey, nsISupports>& GetHash()
+  {
+    return mHash;
+  }
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+private:
+  void RemoveObservers();
+
+  nsInterfaceHashtable<nsCStringHashKey, nsISupports> mHash;
+  nsCString mCategory;
+  bool mObserversRemoved;
+};
+
+/**
+ * This is a helper class that caches services that are registered in a certain
+ * category. The intended usage is that a service stores a variable of type
+ * nsCategoryCache<nsIFoo> in a member variable, where nsIFoo is the interface
+ * that these services should implement. The constructor of this class should
+ * then get the name of the category.
+ */
+template<class T>
+class nsCategoryCache final
+{
+public:
+  explicit nsCategoryCache(const char* aCategory)
+    : mCategoryName(aCategory)
+  {
+  }
+  ~nsCategoryCache()
+  {
+    if (mObserver) {
+      mObserver->ListenerDied();
+    }
+  }
+
+  void GetEntries(nsCOMArray<T>& aResult)
+  {
+    // Lazy initialization, so that services in this category can't
+    // cause reentrant getService (bug 386376)
+    if (!mObserver) {
+      mObserver = new nsCategoryObserver(mCategoryName.get());
+    }
+
+    for (auto iter = mObserver->GetHash().Iter(); !iter.Done(); iter.Next()) {
+      nsISupports* entry = iter.UserData();
+      nsCOMPtr<T> service = do_QueryInterface(entry);
+      if (service) {
+        aResult.AppendElement(service.forget());
+      }
+    }
+  }
+
+private:
+  // Not to be implemented
+  nsCategoryCache(const nsCategoryCache<T>&);
+
+  nsCString mCategoryName;
+  RefPtr<nsCategoryObserver> mObserver;
+};
+
+#endif
diff --git a/xpcom/glue/nsClassHashtable.h b/xpcom/glue/nsClassHashtable.h
new file mode 100644
index 000000000..53ca5676b
--- /dev/null
+++ b/xpcom/glue/nsClassHashtable.h
@@ -0,0 +1,140 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsClassHashtable_h__
+#define nsClassHashtable_h__
+
+#include "mozilla/Move.h"
+#include "nsBaseHashtable.h"
+#include "nsHashKeys.h"
+#include "nsAutoPtr.h"
+
+/**
+ * templated hashtable class maps keys to C++ object pointers.
+ * See nsBaseHashtable for complete declaration.
+ * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
+ *   for a complete specification.
+ * @param Class the class-type being wrapped
+ * @see nsInterfaceHashtable, nsClassHashtable
+ */
+template<class KeyClass, class T>
+class nsClassHashtable
+  : public nsBaseHashtable<KeyClass, nsAutoPtr<T>, T*>
+{
+public:
+  typedef typename KeyClass::KeyType KeyType;
+  typedef T* UserDataType;
+  typedef nsBaseHashtable<KeyClass, nsAutoPtr<T>, T*> base_type;
+
+  using base_type::IsEmpty;
+
+  nsClassHashtable() {}
+  explicit nsClassHashtable(uint32_t aInitLength)
+    : nsBaseHashtable<KeyClass, nsAutoPtr<T>, T*>(aInitLength)
+  {
+  }
+
+  /**
+   * Looks up aKey in the hash table. If it doesn't exist a new object of
+   * KeyClass will be created (using the arguments provided) and then returned.
+   */
+  template<typename... Args>
+  UserDataType LookupOrAdd(KeyType aKey, Args&&... aConstructionArgs);
+
+  /**
+   * @copydoc nsBaseHashtable::Get
+   * @param aData if the key doesn't exist, pData will be set to nullptr.
+   */
+  bool Get(KeyType aKey, UserDataType* aData) const;
+
+  /**
+   * @copydoc nsBaseHashtable::Get
+   * @returns nullptr if the key is not present.
+   */
+  UserDataType Get(KeyType aKey) const;
+
+  /**
+   * Remove the entry for the given key from the hashtable and return it in
+   * aOut.  If the key is not in the hashtable, aOut's pointer is set to
+   * nullptr.
+   *
+   * Normally, an entry is deleted when it's removed from an nsClassHashtable,
+   * but this function transfers ownership of the entry back to the caller
+   * through aOut -- the entry will be deleted when aOut goes out of scope.
+   *
+   * @param aKey the key to get and remove from the hashtable
+   */
+  void RemoveAndForget(KeyType aKey, nsAutoPtr<T>& aOut);
+};
+
+//
+// nsClassHashtable definitions
+//
+
+template<class KeyClass, class T>
+template<typename... Args>
+T*
+nsClassHashtable<KeyClass, T>::LookupOrAdd(KeyType aKey,
+                                           Args&&... aConstructionArgs)
+{
+  typename base_type::EntryType* ent = this->PutEntry(aKey);
+  if (!ent->mData) {
+    ent->mData = new T(mozilla::Forward<Args>(aConstructionArgs)...);
+  }
+  return ent->mData;
+}
+
+template<class KeyClass, class T>
+bool
+nsClassHashtable<KeyClass, T>::Get(KeyType aKey, T** aRetVal) const
+{
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+
+  if (ent) {
+    if (aRetVal) {
+      *aRetVal = ent->mData;
+    }
+
+    return true;
+  }
+
+  if (aRetVal) {
+    *aRetVal = nullptr;
+  }
+
+  return false;
+}
+
+template<class KeyClass, class T>
+T*
+nsClassHashtable<KeyClass, T>::Get(KeyType aKey) const
+{
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+  if (!ent) {
+    return nullptr;
+  }
+
+  return ent->mData;
+}
+
+template<class KeyClass, class T>
+void
+nsClassHashtable<KeyClass, T>::RemoveAndForget(KeyType aKey, nsAutoPtr<T>& aOut)
+{
+  aOut = nullptr;
+
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+  if (!ent) {
+    return;
+  }
+
+  // Transfer ownership from ent->mData into aOut.
+  aOut = mozilla::Move(ent->mData);
+
+  this->Remove(aKey);
+}
+
+#endif // nsClassHashtable_h__
diff --git a/xpcom/glue/nsClassInfoImpl.cpp b/xpcom/glue/nsClassInfoImpl.cpp
new file mode 100644
index 000000000..6eb34f9f7
--- /dev/null
+++ b/xpcom/glue/nsClassInfoImpl.cpp
@@ -0,0 +1,73 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIClassInfoImpl.h"
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+GenericClassInfo::AddRef()
+{
+  return 2;
+}
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+GenericClassInfo::Release()
+{
+  return 1;
+}
+
+NS_IMPL_QUERY_INTERFACE(GenericClassInfo, nsIClassInfo)
+
+NS_IMETHODIMP
+GenericClassInfo::GetInterfaces(uint32_t* aCount, nsIID*** aArray)
+{
+  return mData->getinterfaces(aCount, aArray);
+}
+
+NS_IMETHODIMP
+GenericClassInfo::GetScriptableHelper(nsIXPCScriptable** aHelper)
+{
+  if (mData->getscriptablehelper) {
+    return mData->getscriptablehelper(aHelper);
+  }
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+GenericClassInfo::GetContractID(char** aContractID)
+{
+  NS_ERROR("GetContractID not implemented");
+  *aContractID = nullptr;
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+GenericClassInfo::GetClassDescription(char** aDescription)
+{
+  *aDescription = nullptr;
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+GenericClassInfo::GetClassID(nsCID** aClassID)
+{
+  NS_ERROR("GetClassID not implemented");
+  *aClassID = nullptr;
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+GenericClassInfo::GetFlags(uint32_t* aFlags)
+{
+  *aFlags = mData->flags;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+GenericClassInfo::GetClassIDNoAlloc(nsCID* aClassIDNoAlloc)
+{
+  *aClassIDNoAlloc = mData->cid;
+  return NS_OK;
+}
diff --git a/xpcom/glue/nsComponentManagerUtils.cpp b/xpcom/glue/nsComponentManagerUtils.cpp
new file mode 100644
index 000000000..d8a590fa7
--- /dev/null
+++ b/xpcom/glue/nsComponentManagerUtils.cpp
@@ -0,0 +1,301 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsXPCOM_h__
+#include "nsXPCOM.h"
+#endif
+
+#ifndef nsCOMPtr_h__
+#include "nsCOMPtr.h"
+#endif
+
+#include "nsComponentManagerUtils.h"
+#include "nsServiceManagerUtils.h"
+
+#include "nsIComponentManager.h"
+
+#ifndef MOZILLA_INTERNAL_API
+
+nsresult
+CallGetService(const nsCID& aCID, const nsIID& aIID, void** aResult)
+{
+  nsCOMPtr<nsIServiceManager> servMgr;
+  nsresult status = NS_GetServiceManager(getter_AddRefs(servMgr));
+  if (servMgr) {
+    status = servMgr->GetService(aCID, aIID, aResult);
+  }
+  return status;
+}
+
+nsresult
+CallGetService(const char* aContractID, const nsIID& aIID, void** aResult)
+{
+  nsCOMPtr<nsIServiceManager> servMgr;
+  nsresult status = NS_GetServiceManager(getter_AddRefs(servMgr));
+  if (servMgr) {
+    status = servMgr->GetServiceByContractID(aContractID, aIID, aResult);
+  }
+  return status;
+}
+
+#else
+
+#include "nsComponentManager.h"
+
+nsresult
+CallGetService(const nsCID& aCID, const nsIID& aIID, void** aResult)
+{
+  nsComponentManagerImpl* compMgr = nsComponentManagerImpl::gComponentManager;
+  if (NS_WARN_IF(!compMgr)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return compMgr->nsComponentManagerImpl::GetService(aCID, aIID, aResult);
+}
+
+nsresult
+CallGetService(const char* aContractID, const nsIID& aIID, void** aResult)
+{
+  nsComponentManagerImpl* compMgr = nsComponentManagerImpl::gComponentManager;
+  if (NS_WARN_IF(!compMgr)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return compMgr->nsComponentManagerImpl::GetServiceByContractID(aContractID,
+                                                                 aIID,
+                                                                 aResult);
+}
+
+#endif
+
+#ifndef MOZILLA_INTERNAL_API
+
+nsresult
+CallCreateInstance(const nsCID& aCID, nsISupports* aDelegate,
+                   const nsIID& aIID, void** aResult)
+{
+  nsCOMPtr<nsIComponentManager> compMgr;
+  nsresult status = NS_GetComponentManager(getter_AddRefs(compMgr));
+  if (compMgr) {
+    status = compMgr->CreateInstance(aCID, aDelegate, aIID, aResult);
+  }
+  return status;
+}
+
+nsresult
+CallCreateInstance(const char* aContractID, nsISupports* aDelegate,
+                   const nsIID& aIID, void** aResult)
+{
+  nsCOMPtr<nsIComponentManager> compMgr;
+  nsresult status = NS_GetComponentManager(getter_AddRefs(compMgr));
+  if (compMgr)
+    status = compMgr->CreateInstanceByContractID(aContractID, aDelegate,
+                                                 aIID, aResult);
+  return status;
+}
+
+nsresult
+CallGetClassObject(const nsCID& aCID, const nsIID& aIID, void** aResult)
+{
+  nsCOMPtr<nsIComponentManager> compMgr;
+  nsresult status = NS_GetComponentManager(getter_AddRefs(compMgr));
+  if (compMgr) {
+    status = compMgr->GetClassObject(aCID, aIID, aResult);
+  }
+  return status;
+}
+
+nsresult
+CallGetClassObject(const char* aContractID, const nsIID& aIID, void** aResult)
+{
+  nsCOMPtr<nsIComponentManager> compMgr;
+  nsresult status = NS_GetComponentManager(getter_AddRefs(compMgr));
+  if (compMgr)
+    status = compMgr->GetClassObjectByContractID(aContractID, aIID,
+                                                 aResult);
+  return status;
+}
+
+#else
+
+#include "nsComponentManager.h"
+
+nsresult
+CallCreateInstance(const nsCID& aCID, nsISupports* aDelegate,
+                   const nsIID& aIID, void** aResult)
+{
+  nsComponentManagerImpl* compMgr = nsComponentManagerImpl::gComponentManager;
+  if (NS_WARN_IF(!compMgr)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return compMgr->nsComponentManagerImpl::CreateInstance(aCID, aDelegate, aIID,
+                                                         aResult);
+}
+
+nsresult
+CallCreateInstance(const char* aContractID, nsISupports* aDelegate,
+                   const nsIID& aIID, void** aResult)
+{
+  nsComponentManagerImpl* compMgr = nsComponentManagerImpl::gComponentManager;
+  if (NS_WARN_IF(!compMgr)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return
+    compMgr->nsComponentManagerImpl::CreateInstanceByContractID(aContractID,
+                                                                aDelegate, aIID,
+                                                                aResult);
+}
+
+nsresult
+CallGetClassObject(const nsCID& aCID, const nsIID& aIID, void** aResult)
+{
+  nsComponentManagerImpl* compMgr = nsComponentManagerImpl::gComponentManager;
+  if (NS_WARN_IF(!compMgr)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return compMgr->nsComponentManagerImpl::GetClassObject(aCID, aIID, aResult);
+}
+
+nsresult
+CallGetClassObject(const char* aContractID, const nsIID& aIID, void** aResult)
+{
+  nsComponentManagerImpl* compMgr = nsComponentManagerImpl::gComponentManager;
+  if (NS_WARN_IF(!compMgr)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return
+    compMgr->nsComponentManagerImpl::GetClassObjectByContractID(aContractID,
+                                                                aIID, aResult);
+}
+
+#endif
+
+nsresult
+nsCreateInstanceByCID::operator()(const nsIID& aIID, void** aInstancePtr) const
+{
+  nsresult status = CallCreateInstance(mCID, nullptr, aIID, aInstancePtr);
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
+
+nsresult
+nsCreateInstanceByContractID::operator()(const nsIID& aIID,
+                                         void** aInstancePtr) const
+{
+  nsresult status = CallCreateInstance(mContractID, nullptr, aIID, aInstancePtr);
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
+
+nsresult
+nsCreateInstanceFromFactory::operator()(const nsIID& aIID,
+                                        void** aInstancePtr) const
+{
+  nsresult status = mFactory->CreateInstance(nullptr, aIID, aInstancePtr);
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
+
+
+nsresult
+nsGetClassObjectByCID::operator()(const nsIID& aIID, void** aInstancePtr) const
+{
+  nsresult status = CallGetClassObject(mCID, aIID, aInstancePtr);
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
+
+nsresult
+nsGetClassObjectByContractID::operator()(const nsIID& aIID,
+                                         void** aInstancePtr) const
+{
+  nsresult status = CallGetClassObject(mContractID, aIID, aInstancePtr);
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
+
+
+nsresult
+nsGetServiceByCID::operator()(const nsIID& aIID, void** aInstancePtr) const
+{
+  nsresult status = CallGetService(mCID, aIID, aInstancePtr);
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+
+  return status;
+}
+
+nsresult
+nsGetServiceByCIDWithError::operator()(const nsIID& aIID,
+                                       void** aInstancePtr) const
+{
+  nsresult status = CallGetService(mCID, aIID, aInstancePtr);
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
+
+nsresult
+nsGetServiceByContractID::operator()(const nsIID& aIID,
+                                     void** aInstancePtr) const
+{
+  nsresult status = CallGetService(mContractID, aIID, aInstancePtr);
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+
+  return status;
+}
+
+nsresult
+nsGetServiceByContractIDWithError::operator()(const nsIID& aIID,
+                                              void** aInstancePtr) const
+{
+  nsresult status = CallGetService(mContractID, aIID, aInstancePtr);
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
diff --git a/xpcom/glue/nsComponentManagerUtils.h b/xpcom/glue/nsComponentManagerUtils.h
new file mode 100644
index 000000000..2a7a4fbd7
--- /dev/null
+++ b/xpcom/glue/nsComponentManagerUtils.h
@@ -0,0 +1,247 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsComponentManagerUtils_h__
+#define nsComponentManagerUtils_h__
+
+#include "nscore.h"
+#include "nsCOMPtr.h"
+
+#include "nsIFactory.h"
+
+
+nsresult CallCreateInstance(const nsCID& aClass, nsISupports* aDelegate,
+                            const nsIID& aIID, void** aResult);
+
+nsresult CallCreateInstance(const char* aContractID, nsISupports* aDelegate,
+                            const nsIID& aIID, void** aResult);
+
+nsresult CallGetClassObject(const nsCID& aClass, const nsIID& aIID,
+                            void** aResult);
+
+nsresult CallGetClassObject(const char* aContractID, const nsIID& aIID,
+                            void** aResult);
+
+
+class MOZ_STACK_CLASS nsCreateInstanceByCID final : public nsCOMPtr_helper
+{
+public:
+  nsCreateInstanceByCID(const nsCID& aCID, nsresult* aErrorPtr)
+    : mCID(aCID)
+    , mErrorPtr(aErrorPtr)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID&, void**) const
+    override;
+
+private:
+  const nsCID&    mCID;
+  nsresult*       mErrorPtr;
+};
+
+class MOZ_STACK_CLASS nsCreateInstanceByContractID final : public nsCOMPtr_helper
+{
+public:
+  nsCreateInstanceByContractID(const char* aContractID, nsresult* aErrorPtr)
+    : mContractID(aContractID)
+    , mErrorPtr(aErrorPtr)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID&, void**) const override;
+
+private:
+  const char*   mContractID;
+  nsresult*     mErrorPtr;
+};
+
+class MOZ_STACK_CLASS nsCreateInstanceFromFactory final : public nsCOMPtr_helper
+{
+public:
+  nsCreateInstanceFromFactory(nsIFactory* aFactory, nsresult* aErrorPtr)
+    : mFactory(aFactory)
+    , mErrorPtr(aErrorPtr)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID&, void**) const override;
+
+private:
+  nsIFactory* MOZ_NON_OWNING_REF mFactory;
+  nsresult*     mErrorPtr;
+};
+
+
+inline const nsCreateInstanceByCID
+do_CreateInstance(const nsCID& aCID, nsresult* aError = 0)
+{
+  return nsCreateInstanceByCID(aCID, aError);
+}
+
+inline const nsCreateInstanceByContractID
+do_CreateInstance(const char* aContractID, nsresult* aError = 0)
+{
+  return nsCreateInstanceByContractID(aContractID, aError);
+}
+
+inline const nsCreateInstanceFromFactory
+do_CreateInstance(nsIFactory* aFactory, nsresult* aError = 0)
+{
+  return nsCreateInstanceFromFactory(aFactory, aError);
+}
+
+
+class MOZ_STACK_CLASS nsGetClassObjectByCID final : public nsCOMPtr_helper
+{
+public:
+  nsGetClassObjectByCID(const nsCID& aCID, nsresult* aErrorPtr)
+    : mCID(aCID)
+    , mErrorPtr(aErrorPtr)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID&, void**) const override;
+
+private:
+  const nsCID&    mCID;
+  nsresult*       mErrorPtr;
+};
+
+class MOZ_STACK_CLASS nsGetClassObjectByContractID final : public nsCOMPtr_helper
+{
+public:
+  nsGetClassObjectByContractID(const char* aContractID, nsresult* aErrorPtr)
+    : mContractID(aContractID)
+    , mErrorPtr(aErrorPtr)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID&, void**) const override;
+
+private:
+  const char*   mContractID;
+  nsresult*     mErrorPtr;
+};
+
+/**
+ * do_GetClassObject can be used to improve performance of callers
+ * that call |CreateInstance| many times.  They can cache the factory
+ * and call do_CreateInstance or CallCreateInstance with the cached
+ * factory rather than having the component manager retrieve it every
+ * time.
+ */
+inline const nsGetClassObjectByCID
+do_GetClassObject(const nsCID& aCID, nsresult* aError = 0)
+{
+  return nsGetClassObjectByCID(aCID, aError);
+}
+
+inline const nsGetClassObjectByContractID
+do_GetClassObject(const char* aContractID, nsresult* aError = 0)
+{
+  return nsGetClassObjectByContractID(aContractID, aError);
+}
+
+// type-safe shortcuts for calling |CreateInstance|
+template<class DestinationType>
+inline nsresult
+CallCreateInstance(const nsCID& aClass,
+                   nsISupports* aDelegate,
+                   DestinationType** aDestination)
+{
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return CallCreateInstance(aClass, aDelegate,
+                            NS_GET_TEMPLATE_IID(DestinationType),
+                            reinterpret_cast<void**>(aDestination));
+}
+
+template<class DestinationType>
+inline nsresult
+CallCreateInstance(const nsCID& aClass, DestinationType** aDestination)
+{
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return CallCreateInstance(aClass, nullptr,
+                            NS_GET_TEMPLATE_IID(DestinationType),
+                            reinterpret_cast<void**>(aDestination));
+}
+
+template<class DestinationType>
+inline nsresult
+CallCreateInstance(const char* aContractID,
+                   nsISupports* aDelegate,
+                   DestinationType** aDestination)
+{
+  NS_PRECONDITION(aContractID, "null parameter");
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return CallCreateInstance(aContractID,
+                            aDelegate,
+                            NS_GET_TEMPLATE_IID(DestinationType),
+                            reinterpret_cast<void**>(aDestination));
+}
+
+template<class DestinationType>
+inline nsresult
+CallCreateInstance(const char* aContractID, DestinationType** aDestination)
+{
+  NS_PRECONDITION(aContractID, "null parameter");
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return CallCreateInstance(aContractID, nullptr,
+                            NS_GET_TEMPLATE_IID(DestinationType),
+                            reinterpret_cast<void**>(aDestination));
+}
+
+template<class DestinationType>
+inline nsresult
+CallCreateInstance(nsIFactory* aFactory,
+                   nsISupports* aDelegate,
+                   DestinationType** aDestination)
+{
+  NS_PRECONDITION(aFactory, "null parameter");
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return aFactory->CreateInstance(aDelegate,
+                                  NS_GET_TEMPLATE_IID(DestinationType),
+                                  reinterpret_cast<void**>(aDestination));
+}
+
+template<class DestinationType>
+inline nsresult
+CallCreateInstance(nsIFactory* aFactory, DestinationType** aDestination)
+{
+  NS_PRECONDITION(aFactory, "null parameter");
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return aFactory->CreateInstance(nullptr,
+                                  NS_GET_TEMPLATE_IID(DestinationType),
+                                  reinterpret_cast<void**>(aDestination));
+}
+
+template<class DestinationType>
+inline nsresult
+CallGetClassObject(const nsCID& aClass, DestinationType** aDestination)
+{
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return CallGetClassObject(aClass, NS_GET_TEMPLATE_IID(DestinationType),
+                            reinterpret_cast<void**>(aDestination));
+}
+
+template<class DestinationType>
+inline nsresult
+CallGetClassObject(const char* aContractID, DestinationType** aDestination)
+{
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return CallGetClassObject(aContractID, NS_GET_TEMPLATE_IID(DestinationType),
+                            reinterpret_cast<void**>(aDestination));
+}
+
+#endif /* nsComponentManagerUtils_h__ */
diff --git a/xpcom/glue/nsCycleCollectionNoteChild.h b/xpcom/glue/nsCycleCollectionNoteChild.h
new file mode 100644
index 000000000..5d47caefd
--- /dev/null
+++ b/xpcom/glue/nsCycleCollectionNoteChild.h
@@ -0,0 +1,101 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// This header will be included by headers that define refpointer and array classes
+// in order to specialize CC helpers such as ImplCycleCollectionTraverse for them.
+
+#ifndef nsCycleCollectionNoteChild_h__
+#define nsCycleCollectionNoteChild_h__
+
+#include "nsCycleCollectionTraversalCallback.h"
+#include "mozilla/Likely.h"
+#include "mozilla/TypeTraits.h"
+
+enum
+{
+  CycleCollectionEdgeNameArrayFlag = 1
+};
+
+// Just a helper for appending "[i]". Didn't want to pull in string headers here.
+void
+CycleCollectionNoteEdgeNameImpl(nsCycleCollectionTraversalCallback& aCallback,
+                                const char* aName,
+                                uint32_t aFlags = 0);
+
+// Should be inlined so that in the no-debug-info case this is just a simple if().
+MOZ_ALWAYS_INLINE void
+CycleCollectionNoteEdgeName(nsCycleCollectionTraversalCallback& aCallback,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  if (MOZ_UNLIKELY(aCallback.WantDebugInfo())) {
+    CycleCollectionNoteEdgeNameImpl(aCallback, aName, aFlags);
+  }
+}
+
+#define NS_CYCLE_COLLECTION_INNERCLASS                                         \
+        cycleCollection
+
+#define NS_CYCLE_COLLECTION_INNERNAME                                          \
+        _cycleCollectorGlobal
+
+#define NS_CYCLE_COLLECTION_PARTICIPANT(_class)                                \
+        _class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant()
+
+template<typename T>
+nsISupports*
+ToSupports(T* aPtr, typename T::NS_CYCLE_COLLECTION_INNERCLASS* aDummy = 0)
+{
+  return T::NS_CYCLE_COLLECTION_INNERCLASS::Upcast(aPtr);
+}
+
+// The default implementation of this class template is empty, because it
+// should never be used: see the partial specializations below.
+template<typename T,
+         bool IsXPCOM = mozilla::IsBaseOf<nsISupports, T>::value>
+struct CycleCollectionNoteChildImpl
+{
+};
+
+template<typename T>
+struct CycleCollectionNoteChildImpl<T, true>
+{
+  static void Run(nsCycleCollectionTraversalCallback& aCallback, T* aChild)
+  {
+    aCallback.NoteXPCOMChild(ToSupports(aChild));
+  }
+};
+
+template<typename T>
+struct CycleCollectionNoteChildImpl<T, false>
+{
+  static void Run(nsCycleCollectionTraversalCallback& aCallback, T* aChild)
+  {
+    aCallback.NoteNativeChild(aChild, NS_CYCLE_COLLECTION_PARTICIPANT(T));
+  }
+};
+
+// We declare CycleCollectionNoteChild in 3-argument and 4-argument variants,
+// rather than using default arguments, so that forward declarations work
+// regardless of header inclusion order.
+template<typename T>
+inline void
+CycleCollectionNoteChild(nsCycleCollectionTraversalCallback& aCallback,
+                         T* aChild, const char* aName, uint32_t aFlags)
+{
+  CycleCollectionNoteEdgeName(aCallback, aName, aFlags);
+  CycleCollectionNoteChildImpl<T>::Run(aCallback, aChild);
+}
+
+template<typename T>
+inline void
+CycleCollectionNoteChild(nsCycleCollectionTraversalCallback& aCallback,
+                         T* aChild, const char* aName)
+{
+  CycleCollectionNoteChild(aCallback, aChild, aName, 0);
+}
+
+#endif // nsCycleCollectionNoteChild_h__
diff --git a/xpcom/glue/nsCycleCollectionNoteRootCallback.h b/xpcom/glue/nsCycleCollectionNoteRootCallback.h
new file mode 100644
index 000000000..42c43f301
--- /dev/null
+++ b/xpcom/glue/nsCycleCollectionNoteRootCallback.h
@@ -0,0 +1,31 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCycleCollectionNoteRootCallback_h__
+#define nsCycleCollectionNoteRootCallback_h__
+
+class nsCycleCollectionParticipant;
+class nsISupports;
+
+class nsCycleCollectionNoteRootCallback
+{
+public:
+  NS_IMETHOD_(void) NoteXPCOMRoot(nsISupports* aRoot) = 0;
+  NS_IMETHOD_(void) NoteJSRoot(JSObject* aRoot) = 0;
+  NS_IMETHOD_(void) NoteNativeRoot(void* aRoot,
+                                   nsCycleCollectionParticipant* aParticipant) = 0;
+
+  NS_IMETHOD_(void) NoteWeakMapping(JSObject* aMap, JS::GCCellPtr aKey,
+                                    JSObject* aKeyDelegate, JS::GCCellPtr aVal) = 0;
+
+  bool WantAllTraces() const { return mWantAllTraces; }
+protected:
+  nsCycleCollectionNoteRootCallback() : mWantAllTraces(false) {}
+
+  bool mWantAllTraces;
+};
+
+#endif // nsCycleCollectionNoteRootCallback_h__
diff --git a/xpcom/glue/nsCycleCollectionParticipant.cpp b/xpcom/glue/nsCycleCollectionParticipant.cpp
new file mode 100644
index 000000000..973ef2ff5
--- /dev/null
+++ b/xpcom/glue/nsCycleCollectionParticipant.cpp
@@ -0,0 +1,39 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCycleCollectionParticipant.h"
+#include "nsCOMPtr.h"
+
+NS_IMETHODIMP_(void)
+nsXPCOMCycleCollectionParticipant::Root(void* aPtr)
+{
+  nsISupports* s = static_cast<nsISupports*>(aPtr);
+  NS_ADDREF(s);
+}
+
+NS_IMETHODIMP_(void)
+nsXPCOMCycleCollectionParticipant::Unroot(void* aPtr)
+{
+  nsISupports* s = static_cast<nsISupports*>(aPtr);
+  NS_RELEASE(s);
+}
+
+// We define a default trace function because some participants don't need
+// to trace anything, so it is okay for them not to define one.
+NS_IMETHODIMP_(void)
+nsXPCOMCycleCollectionParticipant::Trace(void* aPtr, const TraceCallbacks& aCb,
+                                         void* aClosure)
+{
+}
+
+bool
+nsXPCOMCycleCollectionParticipant::CheckForRightISupports(nsISupports* aSupports)
+{
+  nsISupports* foo;
+  aSupports->QueryInterface(NS_GET_IID(nsCycleCollectionISupports),
+                            reinterpret_cast<void**>(&foo));
+  return aSupports == foo;
+}
diff --git a/xpcom/glue/nsCycleCollectionParticipant.h b/xpcom/glue/nsCycleCollectionParticipant.h
new file mode 100644
index 000000000..2dfbb6750
--- /dev/null
+++ b/xpcom/glue/nsCycleCollectionParticipant.h
@@ -0,0 +1,852 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCycleCollectionParticipant_h__
+#define nsCycleCollectionParticipant_h__
+
+#include "mozilla/MacroArgs.h"
+#include "mozilla/MacroForEach.h"
+#include "nsCycleCollectionNoteChild.h"
+#include "js/RootingAPI.h"
+
+#define NS_XPCOMCYCLECOLLECTIONPARTICIPANT_IID                                 \
+{                                                                              \
+    0x9674489b,                                                                \
+    0x1f6f,                                                                    \
+    0x4550,                                                                    \
+    { 0xa7, 0x30, 0xcc, 0xae, 0xdd, 0x10, 0x4c, 0xf9 }                         \
+}
+
+/**
+ * Special IID to get at the base nsISupports for a class. Usually this is the
+ * canonical nsISupports pointer, but in the case of tearoffs for example it is
+ * the base nsISupports pointer of the tearoff. This allow the cycle collector
+ * to have separate nsCycleCollectionParticipant's for tearoffs or aggregated
+ * classes.
+ */
+#define NS_CYCLECOLLECTIONISUPPORTS_IID                                        \
+{                                                                              \
+    0xc61eac14,                                                                \
+    0x5f7a,                                                                    \
+    0x4481,                                                                    \
+    { 0x96, 0x5e, 0x7e, 0xaa, 0x6e, 0xff, 0xa8, 0x5f }                         \
+}
+
+/**
+ * Just holds the IID so NS_GET_IID works.
+ */
+class nsCycleCollectionISupports
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_CYCLECOLLECTIONISUPPORTS_IID)
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsCycleCollectionISupports,
+                              NS_CYCLECOLLECTIONISUPPORTS_IID)
+
+namespace JS {
+template<class T> class Heap;
+} /* namespace JS */
+
+/*
+ * A struct defining pure virtual methods which are called when tracing cycle
+ * collection paticipants.  The appropriate method is called depending on the
+ * type of JS GC thing.
+ */
+struct TraceCallbacks
+{
+  virtual void Trace(JS::Heap<JS::Value>* aPtr, const char* aName,
+                     void* aClosure) const = 0;
+  virtual void Trace(JS::Heap<jsid>* aPtr, const char* aName,
+                     void* aClosure) const = 0;
+  virtual void Trace(JS::Heap<JSObject*>* aPtr, const char* aName,
+                     void* aClosure) const = 0;
+  virtual void Trace(JSObject** aPtr, const char* aName,
+                     void* aClosure) const = 0;
+  virtual void Trace(JS::TenuredHeap<JSObject*>* aPtr, const char* aName,
+                     void* aClosure) const = 0;
+  virtual void Trace(JS::Heap<JSString*>* aPtr, const char* aName,
+                     void* aClosure) const = 0;
+  virtual void Trace(JS::Heap<JSScript*>* aPtr, const char* aName,
+                     void* aClosure) const = 0;
+  virtual void Trace(JS::Heap<JSFunction*>* aPtr, const char* aName,
+                     void* aClosure) const = 0;
+};
+
+/*
+ * An implementation of TraceCallbacks that calls a single function for all JS
+ * GC thing types encountered. Implemented in nsCycleCollectorTraceJSHelpers.cpp.
+ */
+struct TraceCallbackFunc : public TraceCallbacks
+{
+  typedef void (*Func)(JS::GCCellPtr aPtr, const char* aName, void* aClosure);
+
+  explicit TraceCallbackFunc(Func aCb) : mCallback(aCb) {}
+
+  virtual void Trace(JS::Heap<JS::Value>* aPtr, const char* aName,
+                     void* aClosure) const override;
+  virtual void Trace(JS::Heap<jsid>* aPtr, const char* aName,
+                     void* aClosure) const override;
+  virtual void Trace(JS::Heap<JSObject*>* aPtr, const char* aName,
+                     void* aClosure) const override;
+  virtual void Trace(JSObject** aPtr, const char* aName,
+                     void* aClosure) const override;
+  virtual void Trace(JS::TenuredHeap<JSObject*>* aPtr, const char* aName,
+                     void* aClosure) const override;
+  virtual void Trace(JS::Heap<JSString*>* aPtr, const char* aName,
+                     void* aClosure) const override;
+  virtual void Trace(JS::Heap<JSScript*>* aPtr, const char* aName,
+                     void* aClosure) const override;
+  virtual void Trace(JS::Heap<JSFunction*>* aPtr, const char* aName,
+                     void* aClosure) const override;
+
+private:
+  Func mCallback;
+};
+
+/**
+ * Participant implementation classes
+ */
+class NS_NO_VTABLE nsCycleCollectionParticipant
+{
+public:
+  constexpr nsCycleCollectionParticipant() : mMightSkip(false) {}
+  constexpr explicit nsCycleCollectionParticipant(bool aSkip) : mMightSkip(aSkip) {}
+
+  NS_IMETHOD Traverse(void* aPtr, nsCycleCollectionTraversalCallback& aCb) = 0;
+
+  NS_IMETHOD_(void) Root(void* aPtr) = 0;
+  NS_IMETHOD_(void) Unlink(void* aPtr) = 0;
+  NS_IMETHOD_(void) Unroot(void* aPtr) = 0;
+  NS_IMETHOD_(const char*) ClassName() = 0;
+
+  NS_IMETHOD_(void) Trace(void* aPtr, const TraceCallbacks& aCb,
+                          void* aClosure) {}
+
+  // If CanSkip returns true, p is removed from the purple buffer during
+  // a call to nsCycleCollector_forgetSkippable().
+  // Note, calling CanSkip may remove objects from the purple buffer!
+  // If aRemovingAllowed is true, p can be removed from the purple buffer.
+  bool CanSkip(void* aPtr, bool aRemovingAllowed)
+  {
+    return mMightSkip ? CanSkipReal(aPtr, aRemovingAllowed) : false;
+  }
+
+  // If CanSkipInCC returns true, p is skipped when selecting roots for the
+  // cycle collector graph.
+  // Note, calling CanSkipInCC may remove other objects from the purple buffer!
+  bool CanSkipInCC(void* aPtr)
+  {
+    return mMightSkip ? CanSkipInCCReal(aPtr) : false;
+  }
+
+  // If CanSkipThis returns true, p is not added to the graph.
+  // This method is called during cycle collection, so don't
+  // change the state of any objects!
+  bool CanSkipThis(void* aPtr)
+  {
+    return mMightSkip ? CanSkipThisReal(aPtr) : false;
+  }
+
+  NS_IMETHOD_(void) DeleteCycleCollectable(void* aPtr) = 0;
+
+protected:
+  NS_IMETHOD_(bool) CanSkipReal(void* aPtr, bool aRemovingAllowed)
+  {
+    NS_ASSERTION(false, "Forgot to implement CanSkipReal?");
+    return false;
+  }
+  NS_IMETHOD_(bool) CanSkipInCCReal(void* aPtr)
+  {
+    NS_ASSERTION(false, "Forgot to implement CanSkipInCCReal?");
+    return false;
+  }
+  NS_IMETHOD_(bool) CanSkipThisReal(void* aPtr)
+  {
+    NS_ASSERTION(false, "Forgot to implement CanSkipThisReal?");
+    return false;
+  }
+
+private:
+  const bool mMightSkip;
+};
+
+class NS_NO_VTABLE nsScriptObjectTracer : public nsCycleCollectionParticipant
+{
+public:
+  constexpr nsScriptObjectTracer()
+    : nsCycleCollectionParticipant(false)
+  {
+  }
+  constexpr explicit nsScriptObjectTracer(bool aSkip)
+    : nsCycleCollectionParticipant(aSkip)
+  {
+  }
+
+  NS_IMETHOD_(void) Trace(void* aPtr, const TraceCallbacks& aCb,
+                          void* aClosure) override = 0;
+
+  // Implemented in nsCycleCollectorTraceJSHelpers.cpp.
+  static void NoteJSChild(JS::GCCellPtr aGCThing, const char* aName,
+                          void* aClosure);
+};
+
+class NS_NO_VTABLE nsXPCOMCycleCollectionParticipant : public nsScriptObjectTracer
+{
+public:
+  constexpr nsXPCOMCycleCollectionParticipant()
+    : nsScriptObjectTracer(false)
+  {
+  }
+  constexpr explicit nsXPCOMCycleCollectionParticipant(bool aSkip)
+    : nsScriptObjectTracer(aSkip)
+  {
+  }
+
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_XPCOMCYCLECOLLECTIONPARTICIPANT_IID)
+
+  NS_IMETHOD_(void) Root(void* aPtr) override;
+  NS_IMETHOD_(void) Unroot(void* aPtr) override;
+
+  NS_IMETHOD_(void) Trace(void* aPtr, const TraceCallbacks& aCb,
+                          void* aClosure) override;
+
+  static bool CheckForRightISupports(nsISupports* aSupports);
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsXPCOMCycleCollectionParticipant,
+                              NS_XPCOMCYCLECOLLECTIONPARTICIPANT_IID)
+
+///////////////////////////////////////////////////////////////////////////////
+// Helpers for implementing a QI to nsXPCOMCycleCollectionParticipant
+///////////////////////////////////////////////////////////////////////////////
+
+#define NS_CYCLE_COLLECTION_CLASSNAME(_class)                                  \
+        _class::NS_CYCLE_COLLECTION_INNERCLASS
+
+#define NS_IMPL_QUERY_CYCLE_COLLECTION(_class)                                 \
+  if ( aIID.Equals(NS_GET_IID(nsXPCOMCycleCollectionParticipant)) ) {          \
+    *aInstancePtr = NS_CYCLE_COLLECTION_PARTICIPANT(_class);                   \
+    return NS_OK;                                                              \
+  } else
+
+#define NS_IMPL_QUERY_CYCLE_COLLECTION_ISUPPORTS(_class)                       \
+  if ( aIID.Equals(NS_GET_IID(nsCycleCollectionISupports)) ) {                 \
+    *aInstancePtr = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this);       \
+    return NS_OK;                                                              \
+  } else
+
+#define NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION(_class)                        \
+  NS_IMPL_QUERY_CYCLE_COLLECTION(_class)
+
+#define NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION_ISUPPORTS(_class)              \
+  NS_IMPL_QUERY_CYCLE_COLLECTION_ISUPPORTS(_class)
+
+#define NS_INTERFACE_MAP_ENTRIES_CYCLE_COLLECTION(_class)                      \
+  NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION(_class)                              \
+  NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION_ISUPPORTS(_class)
+
+#define NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(_class)                        \
+  NS_INTERFACE_MAP_BEGIN(_class)                                               \
+    NS_INTERFACE_MAP_ENTRIES_CYCLE_COLLECTION(_class)
+
+#define NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(_class)              \
+  NS_INTERFACE_MAP_BEGIN(_class)                                               \
+    NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION(_class)
+
+#define NS_INTERFACE_TABLE_TO_MAP_SEGUE_CYCLE_COLLECTION(_class)  \
+  if (rv == NS_OK) return rv; \
+  nsISupports* foundInterface; \
+  NS_INTERFACE_MAP_ENTRIES_CYCLE_COLLECTION(_class)
+
+#define NS_INTERFACE_TABLE_HEAD_CYCLE_COLLECTION_INHERITED(_class)            \
+  NS_IMETHODIMP _class::QueryInterface(REFNSIID aIID, void** aInstancePtr)    \
+  {                                                                           \
+    NS_PRECONDITION(aInstancePtr, "null out param");                          \
+                                                                              \
+    if ( aIID.Equals(NS_GET_IID(nsXPCOMCycleCollectionParticipant)) ) {       \
+      *aInstancePtr = NS_CYCLE_COLLECTION_PARTICIPANT(_class);                \
+      return NS_OK;                                                           \
+    }                                                                         \
+    nsresult rv;
+
+#define NS_CYCLE_COLLECTION_UPCAST(obj, clazz)                                \
+  NS_CYCLE_COLLECTION_CLASSNAME(clazz)::Upcast(obj)
+
+#ifdef DEBUG
+#define NS_CHECK_FOR_RIGHT_PARTICIPANT(_ptr) _ptr->CheckForRightParticipant()
+#else
+#define NS_CHECK_FOR_RIGHT_PARTICIPANT(_ptr)
+#endif
+
+// The default implementation of this class template is empty, because it
+// should never be used: see the partial specializations below.
+template<typename T,
+         bool IsXPCOM = mozilla::IsBaseOf<nsISupports, T>::value>
+struct DowncastCCParticipantImpl
+{
+};
+
+// Specialization for XPCOM CC participants
+template<typename T>
+struct DowncastCCParticipantImpl<T, true>
+{
+  static T* Run(void* aPtr)
+  {
+    nsISupports* s = static_cast<nsISupports*>(aPtr);
+    MOZ_ASSERT(NS_CYCLE_COLLECTION_CLASSNAME(T)::CheckForRightISupports(s),
+               "not the nsISupports pointer we expect");
+    T* rval =  NS_CYCLE_COLLECTION_CLASSNAME(T)::Downcast(s);
+    NS_CHECK_FOR_RIGHT_PARTICIPANT(rval);
+    return rval;
+  }
+};
+
+// Specialization for native CC participants
+template<typename T>
+struct DowncastCCParticipantImpl<T, false>
+{
+  static T* Run(void* aPtr) { return static_cast<T*>(aPtr); }
+};
+
+template<typename T>
+T*
+DowncastCCParticipant(void* aPtr)
+{
+  return DowncastCCParticipantImpl<T>::Run(aPtr);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Helpers for implementing CanSkip methods
+///////////////////////////////////////////////////////////////////////////////
+
+#define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_BEGIN(_class)                        \
+  NS_IMETHODIMP_(bool)                                                         \
+  NS_CYCLE_COLLECTION_CLASSNAME(_class)::CanSkipReal(void *p,                  \
+                                                     bool aRemovingAllowed)    \
+  {                                                                            \
+    _class *tmp = DowncastCCParticipant<_class >(p);
+
+#define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_END                                  \
+    (void)tmp;                                                                 \
+    return false;                                                              \
+  }
+
+#define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_IN_CC_BEGIN(_class)                  \
+  NS_IMETHODIMP_(bool)                                                         \
+  NS_CYCLE_COLLECTION_CLASSNAME(_class)::CanSkipInCCReal(void *p)              \
+  {                                                                            \
+    _class *tmp = DowncastCCParticipant<_class >(p);
+
+#define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_IN_CC_END                            \
+    (void)tmp;                                                                 \
+    return false;                                                              \
+  }
+
+#define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_THIS_BEGIN(_class)                   \
+  NS_IMETHODIMP_(bool)                                                         \
+  NS_CYCLE_COLLECTION_CLASSNAME(_class)::CanSkipThisReal(void *p)              \
+  {                                                                            \
+    _class *tmp = DowncastCCParticipant<_class >(p);
+
+#define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_THIS_END                             \
+    (void)tmp;                                                                 \
+    return false;                                                              \
+  }
+
+///////////////////////////////////////////////////////////////////////////////
+// Helpers for implementing nsCycleCollectionParticipant::Unlink
+//
+// You need to use NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED if you want
+// the base class Unlink version to be called before your own implementation.
+// You can use NS_IMPL_CYCLE_COLLECTION_UNLINK_END_INHERITED if you want the
+// base class Unlink to get called after your own implementation.  You should
+// never use them together.
+///////////////////////////////////////////////////////////////////////////////
+
+#define NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class)                          \
+  NS_IMETHODIMP_(void)                                                         \
+  NS_CYCLE_COLLECTION_CLASSNAME(_class)::Unlink(void *p)                       \
+  {                                                                            \
+    _class *tmp = DowncastCCParticipant<_class >(p);
+
+#define NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(_class, _base_class)   \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class)                                \
+    nsISupports *s = static_cast<nsISupports*>(p);                             \
+    NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::Unlink(s);
+
+#define NS_IMPL_CYCLE_COLLECTION_UNLINK_HELPER(_field)                        \
+  ImplCycleCollectionUnlink(tmp->_field);
+
+#define NS_IMPL_CYCLE_COLLECTION_UNLINK(...)                                   \
+  MOZ_STATIC_ASSERT_VALID_ARG_COUNT(__VA_ARGS__);                              \
+  MOZ_FOR_EACH(NS_IMPL_CYCLE_COLLECTION_UNLINK_HELPER, (), (__VA_ARGS__))
+
+#define NS_IMPL_CYCLE_COLLECTION_UNLINK_END                                    \
+    (void)tmp;                                                                 \
+  }
+
+#define NS_IMPL_CYCLE_COLLECTION_UNLINK_END_INHERITED(_base_class)             \
+    nsISupports *s = static_cast<nsISupports*>(p);                             \
+    NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::Unlink(s);                     \
+    (void)tmp;                                                                 \
+  }
+
+#define NS_IMPL_CYCLE_COLLECTION_UNLINK_0(_class)                              \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class)                                \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+
+///////////////////////////////////////////////////////////////////////////////
+// Helpers for implementing nsCycleCollectionParticipant::Traverse
+///////////////////////////////////////////////////////////////////////////////
+
+#define NS_IMPL_CYCLE_COLLECTION_DESCRIBE(_class, _refcnt)                     \
+    cb.DescribeRefCountedNode(_refcnt, #_class);
+
+#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INTERNAL(_class)               \
+  NS_IMETHODIMP                                                                \
+  NS_CYCLE_COLLECTION_CLASSNAME(_class)::Traverse                              \
+                         (void *p, nsCycleCollectionTraversalCallback &cb)     \
+  {                                                                            \
+    _class *tmp = DowncastCCParticipant<_class >(p);
+
+#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(_class)                        \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INTERNAL(_class)                     \
+  NS_IMPL_CYCLE_COLLECTION_DESCRIBE(_class, tmp->mRefCnt.get())
+
+// Base class' CC participant should return NS_SUCCESS_INTERRUPTED_TRAVERSE
+// from Traverse if it wants derived classes to not traverse anything from
+// their CC participant.
+
+#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(_class, _base_class) \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INTERNAL(_class)                     \
+    nsISupports *s = static_cast<nsISupports*>(p);                             \
+    if (NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::Traverse(s, cb)            \
+        == NS_SUCCESS_INTERRUPTED_TRAVERSE) {                                  \
+      return NS_SUCCESS_INTERRUPTED_TRAVERSE;                                  \
+    }
+
+#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_HELPER(_field)                       \
+  ImplCycleCollectionTraverse(cb, tmp->_field, #_field, 0);
+
+#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE(...)                                 \
+  MOZ_STATIC_ASSERT_VALID_ARG_COUNT(__VA_ARGS__);                              \
+  MOZ_FOR_EACH(NS_IMPL_CYCLE_COLLECTION_TRAVERSE_HELPER, (), (__VA_ARGS__))
+
+#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_RAWPTR(_field)                       \
+  CycleCollectionNoteChild(cb, tmp->_field, #_field);
+
+#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS                       \
+  {                                                                            \
+  TraceCallbackFunc noteJsChild(&nsScriptObjectTracer::NoteJSChild);           \
+  Trace(p, noteJsChild, &cb);                                                  \
+  }
+
+#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END                                  \
+    (void)tmp;                                                                 \
+    return NS_OK;                                                              \
+  }
+
+///////////////////////////////////////////////////////////////////////////////
+// Helpers for implementing nsScriptObjectTracer::Trace
+///////////////////////////////////////////////////////////////////////////////
+
+#define NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(_class)                                 \
+  void                                                                               \
+  NS_CYCLE_COLLECTION_CLASSNAME(_class)::Trace(void *p,                              \
+                                               const TraceCallbacks &aCallbacks,     \
+                                               void *aClosure)                       \
+  {                                                                                  \
+    _class *tmp = DowncastCCParticipant<_class >(p);
+
+#define NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN_INHERITED(_class, _base_class)    \
+  NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(_class)                                 \
+    nsISupports *s = static_cast<nsISupports*>(p);                             \
+    NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::Trace(s, aCallbacks, aClosure);
+
+#define NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(_field)              \
+  aCallbacks.Trace(&tmp->_field, #_field, aClosure);
+
+// NB: The (void)tmp; hack in the TRACE_END macro exists to support
+// implementations that don't need to do anything in their Trace method.
+// Without this hack, some compilers warn about the unused tmp local.
+#define NS_IMPL_CYCLE_COLLECTION_TRACE_END                                     \
+      (void)tmp;                                                               \
+  }
+
+///////////////////////////////////////////////////////////////////////////////
+// Helpers for implementing a concrete nsCycleCollectionParticipant
+///////////////////////////////////////////////////////////////////////////////
+
+// If a class defines a participant, then QIing an instance of that class to
+// nsXPCOMCycleCollectionParticipant should produce that participant.
+#ifdef DEBUG
+#define NS_CHECK_FOR_RIGHT_PARTICIPANT_BASE                                    \
+    virtual void CheckForRightParticipant()
+#define NS_CHECK_FOR_RIGHT_PARTICIPANT_DERIVED                                 \
+    virtual void CheckForRightParticipant() override
+#define NS_CHECK_FOR_RIGHT_PARTICIPANT_BODY(_class)                            \
+    {                                                                          \
+      nsXPCOMCycleCollectionParticipant *p;                                    \
+      CallQueryInterface(this, &p);                                            \
+      MOZ_ASSERT(p == &NS_CYCLE_COLLECTION_INNERNAME,                          \
+                 #_class " should QI to its own CC participant");              \
+    }
+#define NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class)                            \
+    NS_CHECK_FOR_RIGHT_PARTICIPANT_BASE                                        \
+    NS_CHECK_FOR_RIGHT_PARTICIPANT_BODY(_class)
+#define NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL_INHERITED(_class)                  \
+    NS_CHECK_FOR_RIGHT_PARTICIPANT_DERIVED                                     \
+    NS_CHECK_FOR_RIGHT_PARTICIPANT_BODY(_class)
+#else
+#define NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class)
+#define NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL_INHERITED(_class)
+#endif
+
+#define NS_DECL_CYCLE_COLLECTION_CLASS_NAME_METHOD(_class) \
+  NS_IMETHOD_(const char*) ClassName() override { return #_class; };
+
+
+#define NS_DECL_CYCLE_COLLECTION_CLASS_BODY_NO_UNLINK(_class, _base)           \
+public:                                                                        \
+  NS_IMETHOD Traverse(void *p, nsCycleCollectionTraversalCallback &cb)         \
+    override;                                                                  \
+  NS_DECL_CYCLE_COLLECTION_CLASS_NAME_METHOD(_class)                           \
+  NS_IMETHOD_(void) DeleteCycleCollectable(void *p) override                   \
+  {                                                                            \
+    DowncastCCParticipant<_class>(p)->DeleteCycleCollectable();                \
+  }                                                                            \
+  static _class* Downcast(nsISupports* s)                                      \
+  {                                                                            \
+    return static_cast<_class*>(static_cast<_base*>(s));                       \
+  }                                                                            \
+  static nsISupports* Upcast(_class *p)                                        \
+  {                                                                            \
+    return NS_ISUPPORTS_CAST(_base*, p);                                       \
+  }                                                                            \
+  template<typename T>                                                         \
+  friend nsISupports*                                                          \
+  ToSupports(T* p, NS_CYCLE_COLLECTION_INNERCLASS* dummy);
+
+#define NS_DECL_CYCLE_COLLECTION_CLASS_BODY(_class, _base)                     \
+  NS_DECL_CYCLE_COLLECTION_CLASS_BODY_NO_UNLINK(_class, _base)                 \
+  NS_IMETHOD_(void) Unlink(void *p) override;
+
+#define NS_PARTICIPANT_AS(type, participant)                                   \
+  const_cast<type*>(reinterpret_cast<const type*>(participant))
+
+#define NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class)                 \
+  static constexpr nsXPCOMCycleCollectionParticipant* GetParticipant()         \
+  {                                                                            \
+    return &_class::NS_CYCLE_COLLECTION_INNERNAME;                             \
+  }
+
+/**
+ * We use this macro to force that classes that inherit from a ccable class and
+ * declare their own participant declare themselves as inherited cc classes.
+ * To avoid possibly unnecessary vtables we only do this checking in debug
+ * builds.
+ */
+#ifdef DEBUG
+#define NOT_INHERITED_CANT_OVERRIDE virtual void BaseCycleCollectable() final {}
+#else
+#define NOT_INHERITED_CANT_OVERRIDE
+#endif
+
+#define NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(_class, _base)                \
+class NS_CYCLE_COLLECTION_INNERCLASS                                           \
+ : public nsXPCOMCycleCollectionParticipant                                    \
+{                                                                              \
+  NS_DECL_CYCLE_COLLECTION_CLASS_BODY(_class, _base)                           \
+  NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class)                       \
+};                                                                             \
+NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class)                                    \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;           \
+  NOT_INHERITED_CANT_OVERRIDE
+
+#define NS_DECL_CYCLE_COLLECTION_CLASS(_class)                                 \
+  NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(_class, _class)
+
+// Cycle collector helper for ambiguous classes that can sometimes be skipped.
+#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_CLASS_AMBIGUOUS(_class, _base)        \
+class NS_CYCLE_COLLECTION_INNERCLASS                                             \
+ : public nsXPCOMCycleCollectionParticipant                                      \
+{                                                                                \
+public:                                                                          \
+  constexpr NS_CYCLE_COLLECTION_INNERCLASS ()                                    \
+  : nsXPCOMCycleCollectionParticipant(true) {}                                   \
+private:                                                                         \
+  NS_DECL_CYCLE_COLLECTION_CLASS_BODY(_class, _base)                             \
+  NS_IMETHOD_(bool) CanSkipReal(void *p, bool aRemovingAllowed) override;        \
+  NS_IMETHOD_(bool) CanSkipInCCReal(void *p) override;                           \
+  NS_IMETHOD_(bool) CanSkipThisReal(void *p) override;                           \
+  NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class)                         \
+};                                                                               \
+NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class)                                      \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;             \
+NOT_INHERITED_CANT_OVERRIDE
+
+#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_CLASS(_class)                       \
+        NS_DECL_CYCLE_COLLECTION_SKIPPABLE_CLASS_AMBIGUOUS(_class, _class)
+
+#define NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_AMBIGUOUS(_class, _base)          \
+class NS_CYCLE_COLLECTION_INNERCLASS                                                   \
+ : public nsXPCOMCycleCollectionParticipant                                            \
+{                                                                                      \
+  NS_DECL_CYCLE_COLLECTION_CLASS_BODY(_class, _base)                                   \
+  NS_IMETHOD_(void) Trace(void *p, const TraceCallbacks &cb, void *closure) override;  \
+  NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class)                               \
+};                                                                                     \
+NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class)                                            \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME; \
+NOT_INHERITED_CANT_OVERRIDE
+
+#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_SCRIPT_HOLDER_CLASS_AMBIGUOUS(_class, _base)   \
+class NS_CYCLE_COLLECTION_INNERCLASS                                                      \
+ : public nsXPCOMCycleCollectionParticipant                                               \
+{                                                                                         \
+public:                                                                                   \
+  constexpr NS_CYCLE_COLLECTION_INNERCLASS ()                                             \
+  : nsXPCOMCycleCollectionParticipant(true) {}                                            \
+private:                                                                                  \
+  NS_DECL_CYCLE_COLLECTION_CLASS_BODY(_class, _base)                                      \
+  NS_IMETHOD_(void) Trace(void *p, const TraceCallbacks &cb, void *closure) override;     \
+  NS_IMETHOD_(bool) CanSkipReal(void *p, bool aRemovingAllowed) override;                 \
+  NS_IMETHOD_(bool) CanSkipInCCReal(void *p) override;                                    \
+  NS_IMETHOD_(bool) CanSkipThisReal(void *p) override;                                    \
+  NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class)                                  \
+};                                                                                        \
+NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class)                                               \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME; \
+NOT_INHERITED_CANT_OVERRIDE
+
+#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_SCRIPT_HOLDER_CLASS(_class)  \
+  NS_DECL_CYCLE_COLLECTION_SKIPPABLE_SCRIPT_HOLDER_CLASS_AMBIGUOUS(_class, _class)
+
+#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_SCRIPT_HOLDER_CLASS_INHERITED(_class,       \
+                                                                         _base_class)  \
+class NS_CYCLE_COLLECTION_INNERCLASS                                                   \
+ : public NS_CYCLE_COLLECTION_CLASSNAME(_base_class)                                   \
+{                                                                                      \
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_BODY(_class, _base_class)                   \
+  NS_IMETHOD_(void) Trace(void *p, const TraceCallbacks &cb, void *closure) override;  \
+  NS_IMETHOD_(bool) CanSkipReal(void *p, bool aRemovingAllowed) override;              \
+  NS_IMETHOD_(bool) CanSkipInCCReal(void *p) override;                                 \
+  NS_IMETHOD_(bool) CanSkipThisReal(void *p) override;                                 \
+  NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class)                               \
+}; \
+NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL_INHERITED(_class)  \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
+
+#define NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(_class)  \
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_AMBIGUOUS(_class, _class)
+
+#define NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_BODY_NO_UNLINK(_class,        \
+                                                                _base_class)   \
+public:                                                                        \
+  NS_IMETHOD Traverse(void *p, nsCycleCollectionTraversalCallback &cb)         \
+    override;                                                                  \
+  NS_DECL_CYCLE_COLLECTION_CLASS_NAME_METHOD(_class)                           \
+  static _class* Downcast(nsISupports* s)                                      \
+  {                                                                            \
+    return static_cast<_class*>(static_cast<_base_class*>(                     \
+      NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::Downcast(s)));               \
+  }
+
+#define NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_BODY(_class, _base_class)     \
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_BODY_NO_UNLINK(_class, _base_class) \
+  NS_IMETHOD_(void) Unlink(void *p) override;
+
+#define NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(_class, _base_class)          \
+class NS_CYCLE_COLLECTION_INNERCLASS                                           \
+ : public NS_CYCLE_COLLECTION_CLASSNAME(_base_class)                           \
+{                                                                              \
+public:                                                                        \
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_BODY(_class, _base_class)           \
+  NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class)                       \
+};                                                                             \
+NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL_INHERITED(_class)                          \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
+
+#define NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_NO_UNLINK(_class,             \
+                                                           _base_class)        \
+class NS_CYCLE_COLLECTION_INNERCLASS                                           \
+ : public NS_CYCLE_COLLECTION_CLASSNAME(_base_class)                           \
+{                                                                              \
+public:                                                                        \
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_BODY_NO_UNLINK(_class, _base_class) \
+  NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class)                       \
+};                                                                             \
+NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL_INHERITED(_class)                          \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
+
+#define NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_INHERITED(_class,                 \
+                                                               _base_class)            \
+class NS_CYCLE_COLLECTION_INNERCLASS                                                   \
+ : public NS_CYCLE_COLLECTION_CLASSNAME(_base_class)                                   \
+{                                                                                      \
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_BODY(_class, _base_class)                   \
+  NS_IMETHOD_(void) Trace(void *p, const TraceCallbacks &cb, void *closure)            \
+    override;                                                                          \
+  NS_IMPL_GET_XPCOM_CYCLE_COLLECTION_PARTICIPANT(_class)                               \
+};                                                                                     \
+NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL_INHERITED(_class)                                  \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
+
+// Cycle collector participant declarations.
+
+#define NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS_BODY(_class)                     \
+  public:                                                                      \
+    NS_IMETHOD_(void) Root(void *n) override;                                  \
+    NS_IMETHOD_(void) Unlink(void *n) override;                                \
+    NS_IMETHOD_(void) Unroot(void *n) override;                                \
+    NS_IMETHOD Traverse(void *n, nsCycleCollectionTraversalCallback &cb)       \
+      override;                                                                \
+    NS_DECL_CYCLE_COLLECTION_CLASS_NAME_METHOD(_class)                         \
+    NS_IMETHOD_(void) DeleteCycleCollectable(void *n) override                 \
+    {                                                                          \
+      DowncastCCParticipant<_class>(n)->DeleteCycleCollectable();              \
+    }                                                                          \
+    static _class* Downcast(void* s)                                           \
+    {                                                                          \
+      return DowncastCCParticipant<_class>(s);                                 \
+    }                                                                          \
+    static void* Upcast(_class *p)                                             \
+    {                                                                          \
+      return static_cast<void*>(p);                                            \
+    }
+
+#define NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS(_class)                          \
+  void DeleteCycleCollectable(void)                                            \
+  {                                                                            \
+    delete this;                                                               \
+  }                                                                            \
+  class NS_CYCLE_COLLECTION_INNERCLASS                                         \
+   : public nsCycleCollectionParticipant                                       \
+  {                                                                            \
+    NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS_BODY(_class)                         \
+    static constexpr nsCycleCollectionParticipant* GetParticipant()            \
+    {                                                                          \
+      return &_class::NS_CYCLE_COLLECTION_INNERNAME;                           \
+    }                                                                          \
+  };                                                                           \
+  static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
+
+#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_NATIVE_CLASS(_class)                \
+  void DeleteCycleCollectable(void)                                            \
+  {                                                                            \
+    delete this;                                                               \
+  }                                                                            \
+  class NS_CYCLE_COLLECTION_INNERCLASS                                         \
+   : public nsCycleCollectionParticipant                                       \
+  {                                                                            \
+  public:                                                                      \
+    constexpr NS_CYCLE_COLLECTION_INNERCLASS ()                                \
+    : nsCycleCollectionParticipant(true) {}                                    \
+  private:                                                                     \
+    NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS_BODY(_class)                         \
+    NS_IMETHOD_(bool) CanSkipReal(void *p, bool aRemovingAllowed) override;    \
+    NS_IMETHOD_(bool) CanSkipInCCReal(void *p) override;                       \
+    NS_IMETHOD_(bool) CanSkipThisReal(void *p) override;                       \
+    static nsCycleCollectionParticipant* GetParticipant()                      \
+    {                                                                          \
+      return &_class::NS_CYCLE_COLLECTION_INNERNAME;                           \
+    }                                                                          \
+  };                                                                           \
+  static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
+
+#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_NATIVE_CLASS_WITH_CUSTOM_DELETE(_class) \
+class NS_CYCLE_COLLECTION_INNERCLASS                                           \
+ : public nsCycleCollectionParticipant                                         \
+{                                                                              \
+public:                                                                        \
+  constexpr NS_CYCLE_COLLECTION_INNERCLASS ()                                  \
+  : nsCycleCollectionParticipant(true) {}                                      \
+private:                                                                       \
+  NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS_BODY(_class)                           \
+  NS_IMETHOD_(bool) CanSkipReal(void *p, bool aRemovingAllowed) override;      \
+  NS_IMETHOD_(bool) CanSkipInCCReal(void *p) override;                         \
+  NS_IMETHOD_(bool) CanSkipThisReal(void *p) override;                         \
+  static nsCycleCollectionParticipant* GetParticipant()                        \
+  {                                                                            \
+    return &_class::NS_CYCLE_COLLECTION_INNERNAME;                             \
+  }                                                                            \
+};                                                                             \
+static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
+
+#define NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_NATIVE_CLASS(_class)            \
+  void DeleteCycleCollectable(void)                                            \
+  {                                                                            \
+    delete this;                                                               \
+  }                                                                            \
+  class NS_CYCLE_COLLECTION_INNERCLASS                                         \
+   : public nsScriptObjectTracer                                               \
+  {                                                                            \
+    NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS_BODY(_class)                         \
+    NS_IMETHOD_(void) Trace(void *p, const TraceCallbacks &cb, void *closure)  \
+      override;                                                                \
+    static constexpr nsScriptObjectTracer* GetParticipant()                    \
+    {                                                                          \
+      return &_class::NS_CYCLE_COLLECTION_INNERNAME;                           \
+    }                                                                          \
+  };                                                                           \
+  static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
+
+#define NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(_class, _root_function)           \
+  NS_IMETHODIMP_(void)                                                         \
+  NS_CYCLE_COLLECTION_CLASSNAME(_class)::Root(void *p)                         \
+  {                                                                            \
+    _class *tmp = static_cast<_class*>(p);                                     \
+    tmp->_root_function();                                                     \
+  }
+
+#define NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(_class, _unroot_function)       \
+  NS_IMETHODIMP_(void)                                                         \
+  NS_CYCLE_COLLECTION_CLASSNAME(_class)::Unroot(void *p)                       \
+  {                                                                            \
+    _class *tmp = static_cast<_class*>(p);                                     \
+    tmp->_unroot_function();                                                   \
+  }
+
+#define NS_IMPL_CYCLE_COLLECTION_CLASS(_class) \
+ _class::NS_CYCLE_COLLECTION_INNERCLASS _class::NS_CYCLE_COLLECTION_INNERNAME;
+
+// NB: This is not something you usually want to use.  It is here to allow
+// adding things to the CC graph to help debugging via CC logs, but it does not
+// traverse or unlink anything, so it is useless for anything else.
+#define NS_IMPL_CYCLE_COLLECTION_0(_class)                                     \
+  NS_IMPL_CYCLE_COLLECTION_CLASS(_class)                                       \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class)                                \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_END                                          \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(_class)                              \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+#define NS_IMPL_CYCLE_COLLECTION(_class, ...)                                  \
+  NS_IMPL_CYCLE_COLLECTION_CLASS(_class)                                       \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class)                                \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(__VA_ARGS__)                                 \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_END                                          \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(_class)                              \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(__VA_ARGS__)                               \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+// If you are looking for NS_IMPL_CYCLE_COLLECTION_INHERITED_0(_class, _base)
+// you should instead not declare any cycle collected stuff in _class, so it
+// will just inherit the CC declarations from _base.
+
+#define NS_IMPL_CYCLE_COLLECTION_INHERITED(_class, _base, ...)                 \
+  NS_IMPL_CYCLE_COLLECTION_CLASS(_class)                                       \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(_class, _base)               \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(__VA_ARGS__)                                 \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_END                                          \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(_class, _base)             \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(__VA_ARGS__)                               \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+#define NS_CYCLE_COLLECTION_NOTE_EDGE_NAME CycleCollectionNoteEdgeName
+
+#endif // nsCycleCollectionParticipant_h__
diff --git a/xpcom/glue/nsCycleCollectionTraversalCallback.h b/xpcom/glue/nsCycleCollectionTraversalCallback.h
new file mode 100644
index 000000000..9e314af9b
--- /dev/null
+++ b/xpcom/glue/nsCycleCollectionTraversalCallback.h
@@ -0,0 +1,62 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCycleCollectionTraversalCallback_h__
+#define nsCycleCollectionTraversalCallback_h__
+
+#include "jspubtd.h"
+#include "js/HeapAPI.h"
+#include "nsISupports.h"
+
+class nsCycleCollectionParticipant;
+
+class NS_NO_VTABLE nsCycleCollectionTraversalCallback
+{
+public:
+  // You must call DescribeRefCountedNode() with an accurate
+  // refcount, otherwise cycle collection will fail, and probably crash.
+  // If the callback cares about objname, it should put
+  // WANT_DEBUG_INFO in mFlags.
+  NS_IMETHOD_(void) DescribeRefCountedNode(nsrefcnt aRefcount,
+                                           const char* aObjName) = 0;
+  // Note, aCompartmentAddress is 0 if it is unknown.
+  NS_IMETHOD_(void) DescribeGCedNode(bool aIsMarked,
+                                     const char* aObjName,
+                                     uint64_t aCompartmentAddress = 0) = 0;
+
+  NS_IMETHOD_(void) NoteXPCOMChild(nsISupports* aChild) = 0;
+  NS_IMETHOD_(void) NoteJSChild(const JS::GCCellPtr& aThing) = 0;
+  NS_IMETHOD_(void) NoteNativeChild(void* aChild,
+                                    nsCycleCollectionParticipant* aHelper) = 0;
+
+  // Give a name to the edge associated with the next call to
+  // NoteXPCOMChild, NoteJSObject, NoteJSScript, or NoteNativeChild.
+  // Callbacks who care about this should set WANT_DEBUG_INFO in the
+  // flags.
+  NS_IMETHOD_(void) NoteNextEdgeName(const char* aName) = 0;
+
+  enum
+  {
+    // Values for flags:
+
+    // Caller should call NoteNextEdgeName and pass useful objName
+    // to DescribeRefCountedNode and DescribeGCedNode.
+    WANT_DEBUG_INFO = (1 << 0),
+
+    // Caller should not skip objects that we know will be
+    // uncollectable.
+    WANT_ALL_TRACES = (1 << 1)
+  };
+  uint32_t Flags() const { return mFlags; }
+  bool WantDebugInfo() const { return (mFlags & WANT_DEBUG_INFO) != 0; }
+  bool WantAllTraces() const { return (mFlags & WANT_ALL_TRACES) != 0; }
+protected:
+  nsCycleCollectionTraversalCallback() : mFlags(0) {}
+
+  uint32_t mFlags;
+};
+
+#endif // nsCycleCollectionTraversalCallback_h__
diff --git a/xpcom/glue/nsDataHashtable.h b/xpcom/glue/nsDataHashtable.h
new file mode 100644
index 000000000..19c0728b4
--- /dev/null
+++ b/xpcom/glue/nsDataHashtable.h
@@ -0,0 +1,58 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsDataHashtable_h__
+#define nsDataHashtable_h__
+
+#include "nsHashKeys.h"
+#include "nsBaseHashtable.h"
+#include "mozilla/Maybe.h"
+
+/**
+ * templated hashtable class maps keys to simple datatypes.
+ * See nsBaseHashtable for complete declaration
+ * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
+ *   for a complete specification.
+ * @param DataType the simple datatype being wrapped
+ * @see nsInterfaceHashtable, nsClassHashtable
+ */
+template<class KeyClass, class DataType>
+class nsDataHashtable
+  : public nsBaseHashtable<KeyClass, DataType, DataType>
+{
+private:
+  typedef nsBaseHashtable<KeyClass, DataType, DataType> BaseClass;
+
+public:
+  using typename BaseClass::KeyType;
+  using typename BaseClass::EntryType;
+
+  nsDataHashtable() {}
+  explicit nsDataHashtable(uint32_t aInitLength)
+    : BaseClass(aInitLength)
+  {
+  }
+
+  /**
+   * Retrieve the value for a key and remove the corresponding entry at
+   * the same time.
+   *
+   * @param aKey the key to retrieve and remove
+   * @return the found value, or Nothing if no entry was found with the
+   *   given key.
+   */
+  mozilla::Maybe<DataType> GetAndRemove(KeyType aKey)
+  {
+    mozilla::Maybe<DataType> value;
+    if (EntryType* ent = this->GetEntry(aKey)) {
+      value.emplace(mozilla::Move(ent->mData));
+      this->RemoveEntry(ent);
+    }
+    return value;
+  }
+};
+
+#endif // nsDataHashtable_h__
diff --git a/xpcom/glue/nsDebug.h b/xpcom/glue/nsDebug.h
new file mode 100644
index 000000000..7365f9ce3
--- /dev/null
+++ b/xpcom/glue/nsDebug.h
@@ -0,0 +1,460 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsDebug_h___
+#define nsDebug_h___
+
+#include "nscore.h"
+#include "nsError.h"
+
+#include "nsXPCOM.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Likely.h"
+#include <stdarg.h>
+
+#ifdef DEBUG
+#include "prprf.h"
+#endif
+
+/**
+ * Warn if the given condition is true. The condition is evaluated in both
+ * release and debug builds, and the result is an expression which can be
+ * used in subsequent expressions, such as:
+ *
+ * if (NS_WARN_IF(NS_FAILED(rv)) {
+ *   return rv;
+ * }
+ *
+ * This explicit warning and return is preferred to the NS_ENSURE_* macros
+ * which hide the warning and the return control flow.
+ *
+ * This macro can also be used outside of conditions just to issue a warning,
+ * like so:
+ *
+ *   Unused << NS_WARN_IF(NS_FAILED(FnWithSideEffects());
+ *
+ * (The |Unused <<| is necessary because of the MOZ_MUST_USE annotation.)
+ *
+ * However, note that the argument to this macro is evaluated in all builds. If
+ * you just want a warning assertion, it is better to use NS_WARNING_ASSERTION
+ * (which evaluates the condition only in debug builds) like so:
+ *
+ *   NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "operation failed");
+ *
+ * @note This is C++-only
+ */
+#ifdef __cplusplus
+#ifdef DEBUG
+inline MOZ_MUST_USE bool NS_warn_if_impl(bool aCondition, const char* aExpr,
+                                         const char* aFile, int32_t aLine)
+{
+  if (MOZ_UNLIKELY(aCondition)) {
+    NS_DebugBreak(NS_DEBUG_WARNING, nullptr, aExpr, aFile, aLine);
+  }
+  return aCondition;
+}
+#define NS_WARN_IF(condition) \
+  NS_warn_if_impl(condition, #condition, __FILE__, __LINE__)
+#else
+#define NS_WARN_IF(condition) (bool)(condition)
+#endif
+#endif
+
+/**
+ * Test an assertion for truth. If the expression is not true then
+ * emit a warning.
+ *
+ * Program execution continues past the usage of this macro.
+ *
+ * Note also that the non-debug version of this macro does <b>not</b>
+ * evaluate the message argument.
+ */
+#ifdef DEBUG
+#define NS_WARNING_ASSERTION(_expr, _msg)                     \
+  do {                                                        \
+    if (!(_expr)) {                                           \
+      NS_DebugBreak(NS_DEBUG_WARNING, _msg, #_expr, __FILE__, __LINE__); \
+    }                                                         \
+  } while(0)
+#else
+#define NS_WARNING_ASSERTION(_expr, _msg)  do { /* nothing */ } while(0)
+#endif
+
+/**
+ * Test an assertion for truth. If the expression is not true then
+ * trigger a program failure.
+ *
+ * Note that the non-debug version of this macro does <b>not</b>
+ * evaluate the message argument.
+ */
+#ifdef DEBUG
+inline void MOZ_PretendNoReturn()
+  MOZ_PRETEND_NORETURN_FOR_STATIC_ANALYSIS {}
+#define NS_ASSERTION(expr, str)                               \
+  do {                                                        \
+    if (!(expr)) {                                            \
+      NS_DebugBreak(NS_DEBUG_ASSERTION, str, #expr, __FILE__, __LINE__); \
+      MOZ_PretendNoReturn();                                         \
+    }                                                         \
+  } while(0)
+#else
+#define NS_ASSERTION(expr, str)        do { /* nothing */ } while(0)
+#endif
+
+/**
+ * NS_PRECONDITION/POSTCONDITION are synonyms for NS_ASSERTION.
+ */
+#define NS_PRECONDITION(expr, str) NS_ASSERTION(expr, str)
+#define NS_POSTCONDITION(expr, str) NS_ASSERTION(expr, str)
+
+/**
+ * This macros triggers a program failure if executed. It indicates that
+ * an attempt was made to execute some unimplemented functionality.
+ */
+#ifdef DEBUG
+#define NS_NOTYETIMPLEMENTED(str)                             \
+  do {                                                        \
+    NS_DebugBreak(NS_DEBUG_ASSERTION, str, "NotYetImplemented", __FILE__, __LINE__); \
+    MOZ_PretendNoReturn();                                    \
+  } while(0)
+#else
+#define NS_NOTYETIMPLEMENTED(str)      do { /* nothing */ } while(0)
+#endif
+
+/**
+ * This macros triggers a program failure if executed. It indicates that
+ * an attempt was made to execute a codepath which should not be reachable.
+ */
+#ifdef DEBUG
+#define NS_NOTREACHED(str)                                    \
+  do {                                                        \
+    NS_DebugBreak(NS_DEBUG_ASSERTION, str, "Not Reached", __FILE__, __LINE__); \
+    MOZ_PretendNoReturn();                                    \
+  } while(0)
+#else
+#define NS_NOTREACHED(str)             do { /* nothing */ } while(0)
+#endif
+
+/**
+ * Log an error message.
+ */
+#ifdef DEBUG
+#define NS_ERROR(str)                                         \
+  do {                                                        \
+    NS_DebugBreak(NS_DEBUG_ASSERTION, str, "Error", __FILE__, __LINE__); \
+    MOZ_PretendNoReturn();                                    \
+  } while(0)
+#else
+#define NS_ERROR(str)                  do { /* nothing */ } while(0)
+#endif
+
+/**
+ * Log a warning message.
+ */
+#ifdef DEBUG
+#define NS_WARNING(str)                                       \
+  NS_DebugBreak(NS_DEBUG_WARNING, str, nullptr, __FILE__, __LINE__)
+#else
+#define NS_WARNING(str)                do { /* nothing */ } while(0)
+#endif
+
+/**
+ * Trigger an debug-only abort.
+ *
+ * @see NS_RUNTIMEABORT for release-mode asserts.
+ */
+#ifdef DEBUG
+#define NS_ABORT()                                            \
+  do {                                                        \
+    NS_DebugBreak(NS_DEBUG_ABORT, nullptr, nullptr, __FILE__, __LINE__); \
+    MOZ_PretendNoReturn();                                    \
+  } while(0)
+#else
+#define NS_ABORT()                     do { /* nothing */ } while(0)
+#endif
+
+/**
+ * Trigger a debugger breakpoint, only in debug builds.
+ */
+#ifdef DEBUG
+#define NS_BREAK()                                            \
+  do {                                                        \
+    NS_DebugBreak(NS_DEBUG_BREAK, nullptr, nullptr, __FILE__, __LINE__); \
+    MOZ_PretendNoReturn();                                    \
+  } while(0)
+#else
+#define NS_BREAK()                     do { /* nothing */ } while(0)
+#endif
+
+/******************************************************************************
+** Macros for static assertions.  These are used by the sixgill tool.
+** When the tool is not running these macros are no-ops.
+******************************************************************************/
+
+/* Avoid name collision if included with other headers defining annotations. */
+#ifndef HAVE_STATIC_ANNOTATIONS
+#define HAVE_STATIC_ANNOTATIONS
+
+#ifdef XGILL_PLUGIN
+
+#define STATIC_PRECONDITION(COND)         __attribute__((precondition(#COND)))
+#define STATIC_PRECONDITION_ASSUME(COND)  __attribute__((precondition_assume(#COND)))
+#define STATIC_POSTCONDITION(COND)        __attribute__((postcondition(#COND)))
+#define STATIC_POSTCONDITION_ASSUME(COND) __attribute__((postcondition_assume(#COND)))
+#define STATIC_INVARIANT(COND)            __attribute__((invariant(#COND)))
+#define STATIC_INVARIANT_ASSUME(COND)     __attribute__((invariant_assume(#COND)))
+
+/* Used to make identifiers for assert/assume annotations in a function. */
+#define STATIC_PASTE2(X,Y) X ## Y
+#define STATIC_PASTE1(X,Y) STATIC_PASTE2(X,Y)
+
+#define STATIC_ASSUME(COND)                          \
+  do {                                               \
+    __attribute__((assume_static(#COND), unused))    \
+    int STATIC_PASTE1(assume_static_, __COUNTER__);  \
+  } while(0)
+
+#define STATIC_ASSERT_RUNTIME(COND)                         \
+  do {                                                      \
+    __attribute__((assert_static_runtime(#COND), unused))   \
+    int STATIC_PASTE1(assert_static_runtime_, __COUNTER__); \
+  } while(0)
+
+#else /* XGILL_PLUGIN */
+
+#define STATIC_PRECONDITION(COND)          /* nothing */
+#define STATIC_PRECONDITION_ASSUME(COND)   /* nothing */
+#define STATIC_POSTCONDITION(COND)         /* nothing */
+#define STATIC_POSTCONDITION_ASSUME(COND)  /* nothing */
+#define STATIC_INVARIANT(COND)             /* nothing */
+#define STATIC_INVARIANT_ASSUME(COND)      /* nothing */
+
+#define STATIC_ASSUME(COND)          do { /* nothing */ } while(0)
+#define STATIC_ASSERT_RUNTIME(COND)  do { /* nothing */ } while(0)
+
+#endif /* XGILL_PLUGIN */
+
+#define STATIC_SKIP_INFERENCE STATIC_INVARIANT(skip_inference())
+
+#endif /* HAVE_STATIC_ANNOTATIONS */
+
+/******************************************************************************
+** Macros for terminating execution when an unrecoverable condition is
+** reached.  These need to be compiled regardless of the DEBUG flag.
+******************************************************************************/
+
+/**
+ * Terminate execution <i>immediately</i>, and if possible on the current
+ * platform, in such a way that execution can't be continued by other
+ * code (e.g., by intercepting a signal).
+ */
+#define NS_RUNTIMEABORT(msg)                                    \
+  NS_DebugBreak(NS_DEBUG_ABORT, msg, nullptr, __FILE__, __LINE__)
+
+
+/* Macros for checking the trueness of an expression passed in within an
+ * interface implementation.  These need to be compiled regardless of the
+ * DEBUG flag. New code should use NS_WARN_IF(condition) instead!
+ * @status deprecated
+ */
+
+#define NS_ENSURE_TRUE(x, ret)                                \
+  do {                                                        \
+    if (MOZ_UNLIKELY(!(x))) {                                 \
+       NS_WARNING("NS_ENSURE_TRUE(" #x ") failed");           \
+       return ret;                                            \
+    }                                                         \
+  } while(0)
+
+#define NS_ENSURE_FALSE(x, ret)                               \
+  NS_ENSURE_TRUE(!(x), ret)
+
+#define NS_ENSURE_TRUE_VOID(x)                                \
+  do {                                                        \
+    if (MOZ_UNLIKELY(!(x))) {                                 \
+       NS_WARNING("NS_ENSURE_TRUE(" #x ") failed");           \
+       return;                                                \
+    }                                                         \
+  } while(0)
+
+#define NS_ENSURE_FALSE_VOID(x)                               \
+  NS_ENSURE_TRUE_VOID(!(x))
+
+/******************************************************************************
+** Macros for checking results
+******************************************************************************/
+
+#if defined(DEBUG) && !defined(XPCOM_GLUE_AVOID_NSPR)
+
+#define NS_ENSURE_SUCCESS_BODY(res, ret)                                  \
+    char *msg = PR_smprintf("NS_ENSURE_SUCCESS(%s, %s) failed with "      \
+                            "result 0x%X", #res, #ret, __rv);             \
+    NS_WARNING(msg);                                                      \
+    PR_smprintf_free(msg);
+
+#define NS_ENSURE_SUCCESS_BODY_VOID(res)                                  \
+    char *msg = PR_smprintf("NS_ENSURE_SUCCESS_VOID(%s) failed with "     \
+                            "result 0x%X", #res, __rv);                   \
+    NS_WARNING(msg);                                                      \
+    PR_smprintf_free(msg);
+
+#else
+
+#define NS_ENSURE_SUCCESS_BODY(res, ret)                                  \
+    NS_WARNING("NS_ENSURE_SUCCESS(" #res ", " #ret ") failed");
+
+#define NS_ENSURE_SUCCESS_BODY_VOID(res)                                  \
+    NS_WARNING("NS_ENSURE_SUCCESS_VOID(" #res ") failed");
+
+#endif
+
+#define NS_ENSURE_SUCCESS(res, ret)                                       \
+  do {                                                                    \
+    nsresult __rv = res; /* Don't evaluate |res| more than once */        \
+    if (NS_FAILED(__rv)) {                                                \
+      NS_ENSURE_SUCCESS_BODY(res, ret)                                    \
+      return ret;                                                         \
+    }                                                                     \
+  } while(0)
+
+#define NS_ENSURE_SUCCESS_VOID(res)                                       \
+  do {                                                                    \
+    nsresult __rv = res;                                                  \
+    if (NS_FAILED(__rv)) {                                                \
+      NS_ENSURE_SUCCESS_BODY_VOID(res)                                    \
+      return;                                                             \
+    }                                                                     \
+  } while(0)
+
+/******************************************************************************
+** Macros for checking state and arguments upon entering interface boundaries
+******************************************************************************/
+
+#define NS_ENSURE_ARG(arg)                                    \
+  NS_ENSURE_TRUE(arg, NS_ERROR_INVALID_ARG)
+
+#define NS_ENSURE_ARG_POINTER(arg)                            \
+  NS_ENSURE_TRUE(arg, NS_ERROR_INVALID_POINTER)
+
+#define NS_ENSURE_ARG_MIN(arg, min)                           \
+  NS_ENSURE_TRUE((arg) >= min, NS_ERROR_INVALID_ARG)
+
+#define NS_ENSURE_ARG_MAX(arg, max)                           \
+  NS_ENSURE_TRUE((arg) <= max, NS_ERROR_INVALID_ARG)
+
+#define NS_ENSURE_ARG_RANGE(arg, min, max)                    \
+  NS_ENSURE_TRUE(((arg) >= min) && ((arg) <= max), NS_ERROR_INVALID_ARG)
+
+#define NS_ENSURE_STATE(state)                                \
+  NS_ENSURE_TRUE(state, NS_ERROR_UNEXPECTED)
+
+#define NS_ENSURE_NO_AGGREGATION(outer)                       \
+  NS_ENSURE_FALSE(outer, NS_ERROR_NO_AGGREGATION)
+
+/*****************************************************************************/
+
+#if (defined(DEBUG) || (defined(NIGHTLY_BUILD) && !defined(MOZ_PROFILING))) && !defined(XPCOM_GLUE_AVOID_NSPR)
+  #define MOZ_THREAD_SAFETY_OWNERSHIP_CHECKS_SUPPORTED  1
+#endif
+
+#ifdef XPCOM_GLUE
+  #define NS_CheckThreadSafe(owningThread, msg)
+#else
+  #define NS_CheckThreadSafe(owningThread, msg)                 \
+    if (MOZ_UNLIKELY(owningThread != PR_GetCurrentThread())) {  \
+      MOZ_CRASH(msg);                                           \
+    }
+#endif
+
+#ifdef MOZILLA_INTERNAL_API
+void NS_ABORT_OOM(size_t aSize);
+#else
+inline void NS_ABORT_OOM(size_t)
+{
+  MOZ_CRASH();
+}
+#endif
+
+typedef void (*StderrCallback)(const char* aFmt, va_list aArgs);
+/* When compiling the XPCOM Glue on Windows, we pretend that it's going to
+ * be linked with a static CRT (-MT) even when it's not. This means that we
+ * cannot link to data exports from the CRT, only function exports. So,
+ * instead of referencing "stderr" directly, use fdopen.
+ */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * printf_stderr(...) is much like fprintf(stderr, ...), except that:
+ *  - it calls the callback set through set_stderr_callback
+ *  - on Android and Firefox OS, *instead* of printing to stderr, it
+ *    prints to logcat.  (Newlines in the string lead to multiple lines
+ *    of logcat, but each function call implicitly completes a line even
+ *    if the string does not end with a newline.)
+ *  - on Windows, if a debugger is present, it calls OutputDebugString
+ *    in *addition* to writing to stderr
+ */
+void printf_stderr(const char* aFmt, ...) MOZ_FORMAT_PRINTF(1, 2);
+
+/**
+ * Same as printf_stderr, but taking va_list instead of varargs
+ */
+void vprintf_stderr(const char* aFmt, va_list aArgs);
+
+/**
+ * fprintf_stderr is like fprintf, except that if its file argument
+ * is stderr, it invokes printf_stderr instead.
+ *
+ * This is useful for general debugging code that logs information to a
+ * file, but that you would like to be useful on Android and Firefox OS.
+ * If you use fprintf_stderr instead of fprintf in such debugging code,
+ * then callers can pass stderr to get logging that works on Android and
+ * Firefox OS (and also the other side-effects of using printf_stderr).
+ *
+ * Code that is structured this way needs to be careful not to split a
+ * line of output across multiple calls to fprintf_stderr, since doing
+ * so will cause it to appear in multiple lines in logcat output.
+ * (Producing multiple lines at once is fine.)
+ */
+void fprintf_stderr(FILE* aFile, const char* aFmt, ...) MOZ_FORMAT_PRINTF(2, 3);
+
+// used by the profiler to log stderr in the profiler for more
+// advanced performance debugging and display/layers visualization.
+void set_stderr_callback(StderrCallback aCallback);
+
+#if defined(ANDROID) && !defined(RELEASE_OR_BETA)
+// Call this if you want a copy of stderr logging sent to a file. This is
+// useful to get around logcat overflow problems on android devices, which use
+// a circular logcat buffer and can intermittently drop messages if there's too
+// much spew.
+//
+// This is intended for local debugging only, DO NOT USE IN PRODUCTION CODE.
+// (This is ifndef RELEASE_OR_BETA to catch uses of it that accidentally get
+// checked in). Using this will also prevent the profiler from getting a copy of
+// the stderr messages which it uses for various visualization features.
+//
+// This function can be called from any thread, but if it is called multiple
+// times all invocations must be on the same thread. Invocations after the
+// first one are ignored, so you can safely put it inside a loop, for example.
+// Once this is called there is no way to turn it off; all stderr output from
+// that point forward will go to the file. Note that the output is subject to
+// buffering so make sure you have enough output to flush the messages you care
+// about before you terminate the process.
+//
+// The file passed in should be writable, so on Android devices a path like
+// "/data/local/tmp/blah" is a good one to use as it is world-writable and will
+// work even in B2G child processes which have reduced privileges. Note that the
+// actual file created will have the PID appended to the path you pass in, so
+// that on B2G the output from each process goes to a separate file.
+void copy_stderr_to_file(const char* aFile);
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* nsDebug_h___ */
diff --git a/xpcom/glue/nsDeque.cpp b/xpcom/glue/nsDeque.cpp
new file mode 100644
index 000000000..f9eb18b40
--- /dev/null
+++ b/xpcom/glue/nsDeque.cpp
@@ -0,0 +1,361 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsDeque.h"
+#include "nsISupportsImpl.h"
+#include <string.h>
+#ifdef DEBUG_rickg
+#include <stdio.h>
+#endif
+
+#include "mozilla/CheckedInt.h"
+
+#define modulus(x,y) ((x)%(y))
+
+/**
+ * Standard constructor
+ * @param deallocator, called by Erase and ~nsDeque
+ */
+nsDeque::nsDeque(nsDequeFunctor* aDeallocator)
+{
+  MOZ_COUNT_CTOR(nsDeque);
+  mDeallocator = aDeallocator;
+  mOrigin = mSize = 0;
+  mData = mBuffer; // don't allocate space until you must
+  mCapacity = sizeof(mBuffer) / sizeof(mBuffer[0]);
+  memset(mData, 0, mCapacity * sizeof(mBuffer[0]));
+}
+
+/**
+ * Destructor
+ */
+nsDeque::~nsDeque()
+{
+  MOZ_COUNT_DTOR(nsDeque);
+
+#ifdef DEBUG_rickg
+  char buffer[30];
+  printf("Capacity: %i\n", mCapacity);
+
+  static int mCaps[15] = {0};
+  switch (mCapacity) {
+    case 4:     mCaps[0]++; break;
+    case 8:     mCaps[1]++; break;
+    case 16:    mCaps[2]++; break;
+    case 32:    mCaps[3]++; break;
+    case 64:    mCaps[4]++; break;
+    case 128:   mCaps[5]++; break;
+    case 256:   mCaps[6]++; break;
+    case 512:   mCaps[7]++; break;
+    case 1024:  mCaps[8]++; break;
+    case 2048:  mCaps[9]++; break;
+    case 4096:  mCaps[10]++; break;
+    default:
+      break;
+  }
+#endif
+
+  Erase();
+  if (mData && mData != mBuffer) {
+    free(mData);
+  }
+  mData = 0;
+  SetDeallocator(0);
+}
+
+size_t
+nsDeque::SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+{
+  size_t size = 0;
+  if (mData != mBuffer) {
+    size += aMallocSizeOf(mData);
+  }
+
+  if (mDeallocator) {
+    size += aMallocSizeOf(mDeallocator);
+  }
+
+  return size;
+}
+
+size_t
+nsDeque::SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+{
+  return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+}
+
+/**
+ * Set the functor to be called by Erase()
+ * The deque owns the functor.
+ *
+ * @param   aDeallocator functor object for use by Erase()
+ */
+void
+nsDeque::SetDeallocator(nsDequeFunctor* aDeallocator)
+{
+  delete mDeallocator;
+  mDeallocator = aDeallocator;
+}
+
+/**
+ * Remove all items from container without destroying them.
+ */
+void
+nsDeque::Empty()
+{
+  if (mSize && mData) {
+    memset(mData, 0, mCapacity * sizeof(*mData));
+  }
+  mSize = 0;
+  mOrigin = 0;
+}
+
+/**
+ * Remove and delete all items from container
+ */
+void
+nsDeque::Erase()
+{
+  if (mDeallocator && mSize) {
+    ForEach(*mDeallocator);
+  }
+  Empty();
+}
+
+/**
+ * This method quadruples the size of the deque
+ * Elements in the deque are resequenced so that elements
+ * in the deque are stored sequentially
+ *
+ * @return  whether growing succeeded
+ */
+bool
+nsDeque::GrowCapacity()
+{
+  mozilla::CheckedInt<size_t> newCapacity = mCapacity;
+  newCapacity *= 4;
+
+  NS_ASSERTION(newCapacity.isValid(), "Overflow");
+  if (!newCapacity.isValid()) {
+    return false;
+  }
+
+  // Sanity check the new byte size.
+  mozilla::CheckedInt<size_t> newByteSize = newCapacity;
+  newByteSize *= sizeof(void*);
+
+  NS_ASSERTION(newByteSize.isValid(), "Overflow");
+  if (!newByteSize.isValid()) {
+    return false;
+  }
+
+  void** temp = (void**)malloc(newByteSize.value());
+  if (!temp) {
+    return false;
+  }
+
+  //Here's the interesting part: You can't just move the elements
+  //directly (in situ) from the old buffer to the new one.
+  //Since capacity has changed, the old origin doesn't make
+  //sense anymore. It's better to resequence the elements now.
+
+  memcpy(temp, mData + mOrigin, sizeof(void*) * (mCapacity - mOrigin));
+  memcpy(temp + (mCapacity - mOrigin), mData, sizeof(void*) * mOrigin);
+
+  if (mData != mBuffer) {
+    free(mData);
+  }
+
+  mCapacity = newCapacity.value();
+  mOrigin = 0; //now realign the origin...
+  mData = temp;
+
+  return true;
+}
+
+/**
+ * This method adds an item to the end of the deque.
+ * This operation has the potential to cause the
+ * underlying buffer to resize.
+ *
+ * @param   aItem: new item to be added to deque
+ */
+bool
+nsDeque::Push(void* aItem, const fallible_t&)
+{
+  if (mSize == mCapacity && !GrowCapacity()) {
+    return false;
+  }
+  mData[modulus(mOrigin + mSize, mCapacity)] = aItem;
+  mSize++;
+  return true;
+}
+
+/**
+ * This method adds an item to the front of the deque.
+ * This operation has the potential to cause the
+ * underlying buffer to resize.
+ *
+ * --Commments for GrowCapacity() case
+ * We've grown and shifted which means that the old
+ * final element in the deque is now the first element
+ * in the deque.  This is temporary.
+ * We haven't inserted the new element at the front.
+ *
+ * To continue with the idea of having the front at zero
+ * after a grow, we move the old final item (which through
+ * the voodoo of mOrigin-- is now the first) to its final
+ * position which is conveniently the old length.
+ *
+ * Note that this case only happens when the deque is full.
+ * [And that pieces of this magic only work if the deque is full.]
+ * picture:
+ *   [ABCDEFGH] @[mOrigin:3]:D.
+ * Task: PushFront("Z")
+ * shift mOrigin so, @[mOrigin:2]:C
+ * stretch and rearrange: (mOrigin:0)
+ *   [CDEFGHAB ________ ________ ________]
+ * copy: (The second C is currently out of bounds)
+ *   [CDEFGHAB C_______ ________ ________]
+ * later we will insert Z:
+ *   [ZDEFGHAB C_______ ________ ________]
+ * and increment size: 9. (C is no longer out of bounds)
+ * --
+ * @param   aItem: new item to be added to deque
+ */
+bool
+nsDeque::PushFront(void* aItem, const fallible_t&)
+{
+  
+  if (mOrigin == 0) {
+    mOrigin = mCapacity - 1;
+  } else {
+    mOrigin--;
+  }
+  
+  if (mSize == mCapacity) {
+    if (!GrowCapacity()) {
+      return false;
+    }
+    /* Comments explaining this are above*/
+    mData[mSize] = mData[mOrigin];
+  }
+  mData[mOrigin] = aItem;
+  mSize++;
+  return true;
+}
+
+/**
+ * Remove and return the last item in the container.
+ *
+ * @return  ptr to last item in container
+ */
+void*
+nsDeque::Pop()
+{
+  void* result = 0;
+  if (mSize > 0) {
+    --mSize;
+    size_t offset = modulus(mSize + mOrigin, mCapacity);
+    result = mData[offset];
+    mData[offset] = 0;
+    if (!mSize) {
+      mOrigin = 0;
+    }
+  }
+  return result;
+}
+
+/**
+ * This method gets called you want to remove and return
+ * the first member in the container.
+ *
+ * @return  last item in container
+ */
+void*
+nsDeque::PopFront()
+{
+  void* result = 0;
+  if (mSize > 0) {
+    NS_ASSERTION(mOrigin < mCapacity, "Error: Bad origin");
+    result = mData[mOrigin];
+    mData[mOrigin++] = 0;   //zero it out for debugging purposes.
+    mSize--;
+    // Cycle around if we pop off the end
+    // and reset origin if when we pop the last element
+    if (mCapacity == mOrigin || !mSize) {
+      mOrigin = 0;
+    }
+  }
+  return result;
+}
+
+/**
+ * This method gets called you want to peek at the bottom
+ * member without removing it.
+ *
+ * @return  last item in container
+ */
+void*
+nsDeque::Peek() const
+{
+  void* result = 0;
+  if (mSize > 0) {
+    result = mData[modulus(mSize - 1 + mOrigin, mCapacity)];
+  }
+  return result;
+}
+
+/**
+ * This method gets called you want to peek at the topmost
+ * member without removing it.
+ *
+ * @return  last item in container
+ */
+void*
+nsDeque::PeekFront() const
+{
+  void* result = 0;
+  if (mSize > 0) {
+    result = mData[mOrigin];
+  }
+  return result;
+}
+
+/**
+ * Call this to retrieve the ith element from this container.
+ * Keep in mind that accessing the underlying elements is
+ * done in a relative fashion. Object 0 is not necessarily
+ * the first element (the first element is at mOrigin).
+ *
+ * @param   aIndex : 0 relative offset of item you want
+ * @return  void* or null
+ */
+void*
+nsDeque::ObjectAt(size_t aIndex) const
+{
+  void* result = 0;
+  if (aIndex < mSize) {
+    result = mData[modulus(mOrigin + aIndex, mCapacity)];
+  }
+  return result;
+}
+
+/**
+ * Call this method when you want to iterate all the
+ * members of the container, passing a functor along
+ * to call your code.
+ *
+ * @param   aFunctor object to call for each member
+ * @return  *this
+ */
+void
+nsDeque::ForEach(nsDequeFunctor& aFunctor) const
+{
+  for (size_t i = 0; i < mSize; ++i) {
+    aFunctor(ObjectAt(i));
+  }
+}
diff --git a/xpcom/glue/nsDeque.h b/xpcom/glue/nsDeque.h
new file mode 100644
index 000000000..ace7607d3
--- /dev/null
+++ b/xpcom/glue/nsDeque.h
@@ -0,0 +1,195 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * MODULE NOTES:
+ *
+ * The Deque is a very small, very efficient container object
+ * than can hold elements of type void*, offering the following features:
+ *    Its interface supports pushing and popping of elements.
+ *    It can iterate (via an interator class) its elements.
+ *    When full, it can efficiently resize dynamically.
+ *
+ *
+ * NOTE: The only bit of trickery here is that this deque is
+ * built upon a ring-buffer. Like all ring buffers, the first
+ * element may not be at index[0]. The mOrigin member determines
+ * where the first child is. This point is quietly hidden from
+ * customers of this class.
+ *
+ */
+
+#ifndef _NSDEQUE
+#define _NSDEQUE
+
+#include "nscore.h"
+#include "nsDebug.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/fallible.h"
+#include "mozilla/MemoryReporting.h"
+
+/**
+ * The nsDequeFunctor class is used when you want to create
+ * callbacks between the deque and your generic code.
+ * Use these objects in a call to ForEach();
+ *
+ */
+
+class nsDequeFunctor
+{
+public:
+  virtual void* operator()(void* aObject) = 0;
+  virtual ~nsDequeFunctor() {}
+};
+
+/******************************************************
+ * Here comes the nsDeque class itself...
+ ******************************************************/
+
+/**
+ * The deque (double-ended queue) class is a common container type,
+ * whose behavior mimics a line in your favorite checkout stand.
+ * Classic CS describes the common behavior of a queue as FIFO.
+ * A deque allows insertion and removal at both ends of
+ * the container.
+ *
+ * The deque stores pointers to items.
+ */
+
+class nsDequeIterator;
+
+class nsDeque
+{
+  typedef mozilla::fallible_t fallible_t;
+public:
+  explicit nsDeque(nsDequeFunctor* aDeallocator = nullptr);
+  ~nsDeque();
+
+  /**
+   * Returns the number of elements currently stored in
+   * this deque.
+   *
+   * @return  number of elements currently in the deque
+   */
+  inline size_t GetSize() const { return mSize; }
+
+  /**
+   * Appends new member at the end of the deque.
+   *
+   * @param   item to store in deque
+   */
+  void Push(void* aItem)
+  {
+    if (!Push(aItem, mozilla::fallible)) {
+      NS_ABORT_OOM(mSize * sizeof(void*));
+    }
+  }
+
+  MOZ_MUST_USE bool Push(void* aItem, const fallible_t&);
+
+  /**
+   * Inserts new member at the front of the deque.
+   *
+   * @param   item to store in deque
+   */
+  void PushFront(void* aItem)
+  {
+    if (!PushFront(aItem, mozilla::fallible)) {
+      NS_ABORT_OOM(mSize * sizeof(void*));
+    }
+  }
+
+  MOZ_MUST_USE bool PushFront(void* aItem, const fallible_t&);
+
+  /**
+   * Remove and return the last item in the container.
+   *
+   * @return  the item that was the last item in container
+   */
+  void* Pop();
+
+  /**
+   * Remove and return the first item in the container.
+   *
+   * @return  the item that was first item in container
+   */
+  void* PopFront();
+
+  /**
+   * Retrieve the bottom item without removing it.
+   *
+   * @return  the first item in container
+   */
+
+  void* Peek() const;
+  /**
+   * Return topmost item without removing it.
+   *
+   * @return  the first item in container
+   */
+  void* PeekFront() const;
+
+  /**
+   * Retrieve a member from the deque without removing it.
+   *
+   * @param   index of desired item
+   * @return  element in list
+   */
+  void* ObjectAt(size_t aIndex) const;
+
+  /**
+   * Remove and delete all items from container.
+   * Deletes are handled by the deallocator nsDequeFunctor
+   * which is specified at deque construction.
+   */
+  void Erase();
+
+  /**
+   * Call this method when you want to iterate all the
+   * members of the container, passing a functor along
+   * to call your code.
+   *
+   * @param   aFunctor object to call for each member
+   */
+  void ForEach(nsDequeFunctor& aFunctor) const;
+
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
+
+protected:
+  size_t         mSize;
+  size_t         mCapacity;
+  size_t         mOrigin;
+  nsDequeFunctor* mDeallocator;
+  void*           mBuffer[8];
+  void**          mData;
+
+private:
+
+  /**
+   * Copy constructor (PRIVATE)
+   *
+   * @param aOther another deque
+   */
+  nsDeque(const nsDeque& aOther);
+
+  /**
+   * Deque assignment operator (PRIVATE)
+   *
+   * @param aOther another deque
+   * @return *this
+   */
+  nsDeque& operator=(const nsDeque& aOther);
+
+  bool GrowCapacity();
+  void SetDeallocator(nsDequeFunctor* aDeallocator);
+
+  /**
+   * Remove all items from container without destroying them.
+   */
+  void Empty();
+};
+#endif
diff --git a/xpcom/glue/nsEnumeratorUtils.cpp b/xpcom/glue/nsEnumeratorUtils.cpp
new file mode 100644
index 000000000..d1843a78a
--- /dev/null
+++ b/xpcom/glue/nsEnumeratorUtils.cpp
@@ -0,0 +1,291 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Attributes.h"
+
+#include "nsEnumeratorUtils.h"
+
+#include "nsISimpleEnumerator.h"
+#include "nsIStringEnumerator.h"
+
+#include "nsCOMPtr.h"
+#include "mozilla/RefPtr.h"
+
+class EmptyEnumeratorImpl
+  : public nsISimpleEnumerator
+  , public nsIUTF8StringEnumerator
+  , public nsIStringEnumerator
+{
+public:
+  EmptyEnumeratorImpl() {}
+
+  // nsISupports interface
+  NS_DECL_ISUPPORTS_INHERITED  // not really inherited, but no mRefCnt
+
+  // nsISimpleEnumerator
+  NS_DECL_NSISIMPLEENUMERATOR
+  NS_DECL_NSIUTF8STRINGENUMERATOR
+  // can't use NS_DECL_NSISTRINGENUMERATOR because they share the
+  // HasMore() signature
+  NS_IMETHOD GetNext(nsAString& aResult) override;
+
+  static EmptyEnumeratorImpl* GetInstance()
+  {
+    static const EmptyEnumeratorImpl kInstance;
+    return const_cast<EmptyEnumeratorImpl*>(&kInstance);
+  }
+};
+
+// nsISupports interface
+NS_IMETHODIMP_(MozExternalRefCountType)
+EmptyEnumeratorImpl::AddRef(void)
+{
+  return 2;
+}
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+EmptyEnumeratorImpl::Release(void)
+{
+  return 1;
+}
+
+NS_IMPL_QUERY_INTERFACE(EmptyEnumeratorImpl, nsISimpleEnumerator,
+                        nsIUTF8StringEnumerator, nsIStringEnumerator)
+
+// nsISimpleEnumerator interface
+NS_IMETHODIMP
+EmptyEnumeratorImpl::HasMoreElements(bool* aResult)
+{
+  *aResult = false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+EmptyEnumeratorImpl::HasMore(bool* aResult)
+{
+  *aResult = false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+EmptyEnumeratorImpl::GetNext(nsISupports** aResult)
+{
+  return NS_ERROR_UNEXPECTED;
+}
+
+NS_IMETHODIMP
+EmptyEnumeratorImpl::GetNext(nsACString& aResult)
+{
+  return NS_ERROR_UNEXPECTED;
+}
+
+NS_IMETHODIMP
+EmptyEnumeratorImpl::GetNext(nsAString& aResult)
+{
+  return NS_ERROR_UNEXPECTED;
+}
+
+nsresult
+NS_NewEmptyEnumerator(nsISimpleEnumerator** aResult)
+{
+  *aResult = EmptyEnumeratorImpl::GetInstance();
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+class nsSingletonEnumerator final : public nsISimpleEnumerator
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  // nsISimpleEnumerator methods
+  NS_IMETHOD HasMoreElements(bool* aResult) override;
+  NS_IMETHOD GetNext(nsISupports** aResult) override;
+
+  explicit nsSingletonEnumerator(nsISupports* aValue);
+
+private:
+  ~nsSingletonEnumerator();
+
+protected:
+  nsCOMPtr<nsISupports> mValue;
+  bool mConsumed;
+};
+
+nsSingletonEnumerator::nsSingletonEnumerator(nsISupports* aValue)
+  : mValue(aValue)
+{
+  mConsumed = (mValue ? false : true);
+}
+
+nsSingletonEnumerator::~nsSingletonEnumerator()
+{
+}
+
+NS_IMPL_ISUPPORTS(nsSingletonEnumerator, nsISimpleEnumerator)
+
+NS_IMETHODIMP
+nsSingletonEnumerator::HasMoreElements(bool* aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  *aResult = !mConsumed;
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsSingletonEnumerator::GetNext(nsISupports** aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  if (mConsumed) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  mConsumed = true;
+
+  *aResult = mValue;
+  NS_ADDREF(*aResult);
+  return NS_OK;
+}
+
+nsresult
+NS_NewSingletonEnumerator(nsISimpleEnumerator** aResult,
+                          nsISupports* aSingleton)
+{
+  RefPtr<nsSingletonEnumerator> enumer = new nsSingletonEnumerator(aSingleton);
+  enumer.forget(aResult);
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+class nsUnionEnumerator final : public nsISimpleEnumerator
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  // nsISimpleEnumerator methods
+  NS_IMETHOD HasMoreElements(bool* aResult) override;
+  NS_IMETHOD GetNext(nsISupports** aResult) override;
+
+  nsUnionEnumerator(nsISimpleEnumerator* aFirstEnumerator,
+                    nsISimpleEnumerator* aSecondEnumerator);
+
+private:
+  ~nsUnionEnumerator();
+
+protected:
+  nsCOMPtr<nsISimpleEnumerator> mFirstEnumerator, mSecondEnumerator;
+  bool mConsumed;
+  bool mAtSecond;
+};
+
+nsUnionEnumerator::nsUnionEnumerator(nsISimpleEnumerator* aFirstEnumerator,
+                                     nsISimpleEnumerator* aSecondEnumerator)
+  : mFirstEnumerator(aFirstEnumerator)
+  , mSecondEnumerator(aSecondEnumerator)
+  , mConsumed(false)
+  , mAtSecond(false)
+{
+}
+
+nsUnionEnumerator::~nsUnionEnumerator()
+{
+}
+
+NS_IMPL_ISUPPORTS(nsUnionEnumerator, nsISimpleEnumerator)
+
+NS_IMETHODIMP
+nsUnionEnumerator::HasMoreElements(bool* aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  nsresult rv;
+
+  if (mConsumed) {
+    *aResult = false;
+    return NS_OK;
+  }
+
+  if (!mAtSecond) {
+    rv = mFirstEnumerator->HasMoreElements(aResult);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    if (*aResult) {
+      return NS_OK;
+    }
+
+    mAtSecond = true;
+  }
+
+  rv = mSecondEnumerator->HasMoreElements(aResult);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (*aResult) {
+    return NS_OK;
+  }
+
+  *aResult = false;
+  mConsumed = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsUnionEnumerator::GetNext(nsISupports** aResult)
+{
+  NS_PRECONDITION(aResult != 0, "null ptr");
+  if (!aResult) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  if (mConsumed) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (!mAtSecond) {
+    return mFirstEnumerator->GetNext(aResult);
+  }
+
+  return mSecondEnumerator->GetNext(aResult);
+}
+
+nsresult
+NS_NewUnionEnumerator(nsISimpleEnumerator** aResult,
+                      nsISimpleEnumerator* aFirstEnumerator,
+                      nsISimpleEnumerator* aSecondEnumerator)
+{
+  *aResult = nullptr;
+  if (!aFirstEnumerator) {
+    *aResult = aSecondEnumerator;
+  } else if (!aSecondEnumerator) {
+    *aResult = aFirstEnumerator;
+  } else {
+    nsUnionEnumerator* enumer = new nsUnionEnumerator(aFirstEnumerator,
+                                                      aSecondEnumerator);
+    if (!enumer) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    *aResult = enumer;
+  }
+  NS_ADDREF(*aResult);
+  return NS_OK;
+}
diff --git a/xpcom/glue/nsEnumeratorUtils.h b/xpcom/glue/nsEnumeratorUtils.h
new file mode 100644
index 000000000..f7a0db099
--- /dev/null
+++ b/xpcom/glue/nsEnumeratorUtils.h
@@ -0,0 +1,24 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsEnumeratorUtils_h__
+#define nsEnumeratorUtils_h__
+
+#include "nscore.h"
+
+class nsISupports;
+class nsISimpleEnumerator;
+
+nsresult NS_NewEmptyEnumerator(nsISimpleEnumerator** aResult);
+
+nsresult NS_NewSingletonEnumerator(nsISimpleEnumerator** aResult,
+                                   nsISupports* aSingleton);
+
+nsresult NS_NewUnionEnumerator(nsISimpleEnumerator** aResult,
+                               nsISimpleEnumerator* aFirstEnumerator,
+                               nsISimpleEnumerator* aSecondEnumerator);
+
+#endif /* nsEnumeratorUtils_h__ */
diff --git a/xpcom/glue/nsHashKeys.h b/xpcom/glue/nsHashKeys.h
new file mode 100644
index 000000000..9c688691f
--- /dev/null
+++ b/xpcom/glue/nsHashKeys.h
@@ -0,0 +1,660 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTHashKeys_h__
+#define nsTHashKeys_h__
+
+#include "nsID.h"
+#include "nsISupports.h"
+#include "nsIHashable.h"
+#include "nsAutoPtr.h"
+#include "nsCOMPtr.h"
+#include "PLDHashTable.h"
+#include <new>
+
+#include "nsStringGlue.h"
+#include "nsCRTGlue.h"
+#include "nsUnicharUtils.h"
+#include "nsPointerHashKeys.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "mozilla/HashFunctions.h"
+#include "mozilla/Move.h"
+
+namespace mozilla {
+
+// These are defined analogously to the HashString overloads in mfbt.
+
+inline uint32_t
+HashString(const nsAString& aStr)
+{
+  return HashString(aStr.BeginReading(), aStr.Length());
+}
+
+inline uint32_t
+HashString(const nsACString& aStr)
+{
+  return HashString(aStr.BeginReading(), aStr.Length());
+}
+
+} // namespace mozilla
+
+/** @file nsHashKeys.h
+ * standard HashKey classes for nsBaseHashtable and relatives. Each of these
+ * classes follows the nsTHashtable::EntryType specification
+ *
+ * Lightweight keytypes provided here:
+ * nsStringHashKey
+ * nsCStringHashKey
+ * nsUint32HashKey
+ * nsUint64HashKey
+ * nsFloatHashKey
+ * nsPtrHashKey
+ * nsClearingPtrHashKey
+ * nsVoidPtrHashKey
+ * nsClearingVoidPtrHashKey
+ * nsISupportsHashKey
+ * nsIDHashKey
+ * nsDepCharHashKey
+ * nsCharPtrHashKey
+ * nsUnicharPtrHashKey
+ * nsHashableHashKey
+ * nsGenericHashKey
+ */
+
+/**
+ * hashkey wrapper using nsAString KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+class nsStringHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const nsAString& KeyType;
+  typedef const nsAString* KeyTypePointer;
+
+  explicit nsStringHashKey(KeyTypePointer aStr) : mStr(*aStr) {}
+  nsStringHashKey(const nsStringHashKey& aToCopy) : mStr(aToCopy.mStr) {}
+  ~nsStringHashKey() {}
+
+  KeyType GetKey() const { return mStr; }
+  bool KeyEquals(const KeyTypePointer aKey) const
+  {
+    return mStr.Equals(*aKey);
+  }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(const KeyTypePointer aKey)
+  {
+    return mozilla::HashString(*aKey);
+  }
+
+#ifdef MOZILLA_INTERNAL_API
+  // To avoid double-counting, only measure the string if it is unshared.
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return GetKey().SizeOfExcludingThisIfUnshared(aMallocSizeOf);
+  }
+#endif
+
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  const nsString mStr;
+};
+
+#ifdef MOZILLA_INTERNAL_API
+
+/**
+ * hashkey wrapper using nsAString KeyType
+ *
+ * This is internal-API only because nsCaseInsensitiveStringComparator is
+ * internal-only.
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+class nsStringCaseInsensitiveHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const nsAString& KeyType;
+  typedef const nsAString* KeyTypePointer;
+
+  explicit nsStringCaseInsensitiveHashKey(KeyTypePointer aStr)
+    : mStr(*aStr)
+  {
+    // take it easy just deal HashKey
+  }
+  nsStringCaseInsensitiveHashKey(const nsStringCaseInsensitiveHashKey& aToCopy)
+    : mStr(aToCopy.mStr)
+  {
+  }
+  ~nsStringCaseInsensitiveHashKey() {}
+
+  KeyType GetKey() const { return mStr; }
+  bool KeyEquals(const KeyTypePointer aKey) const
+  {
+    return mStr.Equals(*aKey, nsCaseInsensitiveStringComparator());
+  }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(const KeyTypePointer aKey)
+  {
+    nsAutoString tmKey(*aKey);
+    ToLowerCase(tmKey);
+    return mozilla::HashString(tmKey);
+  }
+  enum { ALLOW_MEMMOVE = true };
+
+  // To avoid double-counting, only measure the string if it is unshared.
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return GetKey().SizeOfExcludingThisIfUnshared(aMallocSizeOf);
+  }
+
+private:
+  const nsString mStr;
+};
+
+#endif
+
+/**
+ * hashkey wrapper using nsACString KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+class nsCStringHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const nsACString& KeyType;
+  typedef const nsACString* KeyTypePointer;
+
+  explicit nsCStringHashKey(const nsACString* aStr) : mStr(*aStr) {}
+  nsCStringHashKey(const nsCStringHashKey& aToCopy) : mStr(aToCopy.mStr) {}
+  ~nsCStringHashKey() {}
+
+  KeyType GetKey() const { return mStr; }
+  bool KeyEquals(KeyTypePointer aKey) const { return mStr.Equals(*aKey); }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return mozilla::HashString(*aKey);
+  }
+
+#ifdef MOZILLA_INTERNAL_API
+  // To avoid double-counting, only measure the string if it is unshared.
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return GetKey().SizeOfExcludingThisIfUnshared(aMallocSizeOf);
+  }
+#endif
+
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  const nsCString mStr;
+};
+
+/**
+ * hashkey wrapper using uint32_t KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+class nsUint32HashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const uint32_t& KeyType;
+  typedef const uint32_t* KeyTypePointer;
+
+  explicit nsUint32HashKey(KeyTypePointer aKey) : mValue(*aKey) {}
+  nsUint32HashKey(const nsUint32HashKey& aToCopy) : mValue(aToCopy.mValue) {}
+  ~nsUint32HashKey() {}
+
+  KeyType GetKey() const { return mValue; }
+  bool KeyEquals(KeyTypePointer aKey) const { return *aKey == mValue; }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey) { return *aKey; }
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  const uint32_t mValue;
+};
+
+/**
+ * hashkey wrapper using uint64_t KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+class nsUint64HashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const uint64_t& KeyType;
+  typedef const uint64_t* KeyTypePointer;
+
+  explicit nsUint64HashKey(KeyTypePointer aKey) : mValue(*aKey) {}
+  nsUint64HashKey(const nsUint64HashKey& aToCopy) : mValue(aToCopy.mValue) {}
+  ~nsUint64HashKey() {}
+
+  KeyType GetKey() const { return mValue; }
+  bool KeyEquals(KeyTypePointer aKey) const { return *aKey == mValue; }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return PLDHashNumber(*aKey);
+  }
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  const uint64_t mValue;
+};
+
+/**
+ * hashkey wrapper using float KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+class nsFloatHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const float& KeyType;
+  typedef const float* KeyTypePointer;
+
+  explicit nsFloatHashKey(KeyTypePointer aKey) : mValue(*aKey) {}
+  nsFloatHashKey(const nsFloatHashKey& aToCopy) : mValue(aToCopy.mValue) {}
+  ~nsFloatHashKey() {}
+
+  KeyType GetKey() const { return mValue; }
+  bool KeyEquals(KeyTypePointer aKey) const { return *aKey == mValue; }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return *reinterpret_cast<const uint32_t*>(aKey);
+  }
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  const float mValue;
+};
+
+/**
+ * hashkey wrapper using nsISupports* KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+class nsISupportsHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef nsISupports* KeyType;
+  typedef const nsISupports* KeyTypePointer;
+
+  explicit nsISupportsHashKey(const nsISupports* aKey)
+    : mSupports(const_cast<nsISupports*>(aKey))
+  {
+  }
+  nsISupportsHashKey(const nsISupportsHashKey& aToCopy)
+    : mSupports(aToCopy.mSupports)
+  {
+  }
+  ~nsISupportsHashKey() {}
+
+  KeyType GetKey() const { return mSupports; }
+  bool KeyEquals(KeyTypePointer aKey) const { return aKey == mSupports; }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return NS_PTR_TO_UINT32(aKey) >> 2;
+  }
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  nsCOMPtr<nsISupports> mSupports;
+};
+
+/**
+ * hashkey wrapper using refcounted * KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+template<class T>
+class nsRefPtrHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef T* KeyType;
+  typedef const T* KeyTypePointer;
+
+  explicit nsRefPtrHashKey(const T* aKey) : mKey(const_cast<T*>(aKey)) {}
+  nsRefPtrHashKey(const nsRefPtrHashKey& aToCopy) : mKey(aToCopy.mKey) {}
+  ~nsRefPtrHashKey() {}
+
+  KeyType GetKey() const { return mKey; }
+  bool KeyEquals(KeyTypePointer aKey) const { return aKey == mKey; }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return NS_PTR_TO_UINT32(aKey) >> 2;
+  }
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  RefPtr<T> mKey;
+};
+
+template<class T>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            nsRefPtrHashKey<T>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  CycleCollectionNoteChild(aCallback, aField.GetKey(), aName, aFlags);
+}
+
+/**
+ * hashkey wrapper using T* KeyType that sets key to nullptr upon
+ * destruction. Relevant only in cases where a memory pointer-scanner
+ * like valgrind might get confused about stale references.
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+
+template<class T>
+class nsClearingPtrHashKey : public nsPtrHashKey<T>
+{
+public:
+  explicit nsClearingPtrHashKey(const T* aKey) : nsPtrHashKey<T>(aKey) {}
+  nsClearingPtrHashKey(const nsClearingPtrHashKey<T>& aToCopy)
+    : nsPtrHashKey<T>(aToCopy)
+  {
+  }
+  ~nsClearingPtrHashKey() { nsPtrHashKey<T>::mKey = nullptr; }
+};
+
+typedef nsClearingPtrHashKey<const void> nsClearingVoidPtrHashKey;
+
+/**
+ * hashkey wrapper using a function pointer KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+template<class T>
+class nsFuncPtrHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef T& KeyType;
+  typedef const T* KeyTypePointer;
+
+  explicit nsFuncPtrHashKey(const T* aKey) : mKey(*const_cast<T*>(aKey)) {}
+  nsFuncPtrHashKey(const nsFuncPtrHashKey<T>& aToCopy) : mKey(aToCopy.mKey) {}
+  ~nsFuncPtrHashKey() {}
+
+  KeyType GetKey() const { return const_cast<T&>(mKey); }
+  bool KeyEquals(KeyTypePointer aKey) const { return *aKey == mKey; }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return NS_PTR_TO_UINT32(*aKey) >> 2;
+  }
+  enum { ALLOW_MEMMOVE = true };
+
+protected:
+  T mKey;
+};
+
+/**
+ * hashkey wrapper using nsID KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+class nsIDHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const nsID& KeyType;
+  typedef const nsID* KeyTypePointer;
+
+  explicit nsIDHashKey(const nsID* aInID) : mID(*aInID) {}
+  nsIDHashKey(const nsIDHashKey& aToCopy) : mID(aToCopy.mID) {}
+  ~nsIDHashKey() {}
+
+  KeyType GetKey() const { return mID; }
+  bool KeyEquals(KeyTypePointer aKey) const { return aKey->Equals(mID); }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    // Hash the nsID object's raw bytes.
+    return mozilla::HashBytes(aKey, sizeof(KeyType));
+  }
+
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  const nsID mID;
+};
+
+/**
+ * hashkey wrapper for "dependent" const char*; this class does not "own"
+ * its string pointer.
+ *
+ * This class must only be used if the strings have a lifetime longer than
+ * the hashtable they occupy. This normally occurs only for static
+ * strings or strings that have been arena-allocated.
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+class nsDepCharHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const char* KeyType;
+  typedef const char* KeyTypePointer;
+
+  explicit nsDepCharHashKey(const char* aKey) : mKey(aKey) {}
+  nsDepCharHashKey(const nsDepCharHashKey& aToCopy) : mKey(aToCopy.mKey) {}
+  ~nsDepCharHashKey() {}
+
+  const char* GetKey() const { return mKey; }
+  bool KeyEquals(const char* aKey) const { return !strcmp(mKey, aKey); }
+
+  static const char* KeyToPointer(const char* aKey) { return aKey; }
+  static PLDHashNumber HashKey(const char* aKey)
+  {
+    return mozilla::HashString(aKey);
+  }
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  const char* mKey;
+};
+
+/**
+ * hashkey wrapper for const char*; at construction, this class duplicates
+ * a string pointed to by the pointer so that it doesn't matter whether or not
+ * the string lives longer than the hash table.
+ */
+class nsCharPtrHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const char* KeyType;
+  typedef const char* KeyTypePointer;
+
+  explicit nsCharPtrHashKey(const char* aKey) : mKey(strdup(aKey)) {}
+  nsCharPtrHashKey(const nsCharPtrHashKey& aToCopy)
+    : mKey(strdup(aToCopy.mKey))
+  {
+  }
+
+  nsCharPtrHashKey(nsCharPtrHashKey&& aOther)
+    : mKey(aOther.mKey)
+  {
+    aOther.mKey = nullptr;
+  }
+
+  ~nsCharPtrHashKey()
+  {
+    if (mKey) {
+      free(const_cast<char*>(mKey));
+    }
+  }
+
+  const char* GetKey() const { return mKey; }
+  bool KeyEquals(KeyTypePointer aKey) const { return !strcmp(mKey, aKey); }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return mozilla::HashString(aKey);
+  }
+
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return aMallocSizeOf(mKey);
+  }
+
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  const char* mKey;
+};
+
+/**
+ * hashkey wrapper for const char16_t*; at construction, this class duplicates
+ * a string pointed to by the pointer so that it doesn't matter whether or not
+ * the string lives longer than the hash table.
+ */
+class nsUnicharPtrHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const char16_t* KeyType;
+  typedef const char16_t* KeyTypePointer;
+
+  explicit nsUnicharPtrHashKey(const char16_t* aKey) : mKey(NS_strdup(aKey)) {}
+  nsUnicharPtrHashKey(const nsUnicharPtrHashKey& aToCopy)
+    : mKey(NS_strdup(aToCopy.mKey))
+  {
+  }
+
+  nsUnicharPtrHashKey(nsUnicharPtrHashKey&& aOther)
+    : mKey(aOther.mKey)
+  {
+    aOther.mKey = nullptr;
+  }
+
+  ~nsUnicharPtrHashKey()
+  {
+    if (mKey) {
+      NS_Free(const_cast<char16_t*>(mKey));
+    }
+  }
+
+  const char16_t* GetKey() const { return mKey; }
+  bool KeyEquals(KeyTypePointer aKey) const { return !NS_strcmp(mKey, aKey); }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return mozilla::HashString(aKey);
+  }
+
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return aMallocSizeOf(mKey);
+  }
+
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  const char16_t* mKey;
+};
+
+/**
+ * Hashtable key class to use with objects that support nsIHashable
+ */
+class nsHashableHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef nsIHashable* KeyType;
+  typedef const nsIHashable* KeyTypePointer;
+
+  explicit nsHashableHashKey(const nsIHashable* aKey)
+    : mKey(const_cast<nsIHashable*>(aKey))
+  {
+  }
+  nsHashableHashKey(const nsHashableHashKey& aToCopy) : mKey(aToCopy.mKey) {}
+  ~nsHashableHashKey() {}
+
+  nsIHashable* GetKey() const { return mKey; }
+
+  bool KeyEquals(const nsIHashable* aKey) const
+  {
+    bool eq;
+    if (NS_SUCCEEDED(mKey->Equals(const_cast<nsIHashable*>(aKey), &eq))) {
+      return eq;
+    }
+    return false;
+  }
+
+  static const nsIHashable* KeyToPointer(nsIHashable* aKey) { return aKey; }
+  static PLDHashNumber HashKey(const nsIHashable* aKey)
+  {
+    uint32_t code = 8888; // magic number if GetHashCode fails :-(
+#ifdef DEBUG
+    nsresult rv =
+#endif
+      const_cast<nsIHashable*>(aKey)->GetHashCode(&code);
+    NS_ASSERTION(NS_SUCCEEDED(rv), "GetHashCode should not throw!");
+    return code;
+  }
+
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  nsCOMPtr<nsIHashable> mKey;
+};
+
+namespace mozilla {
+
+template <typename T>
+PLDHashNumber
+Hash(const T& aValue)
+{
+  return aValue.Hash();
+}
+
+} // namespace mozilla
+
+/**
+ * Hashtable key class to use with objects for which Hash() and operator==()
+ * are defined.
+ */
+template<typename T>
+class nsGenericHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef const T& KeyType;
+  typedef const T* KeyTypePointer;
+
+  explicit nsGenericHashKey(KeyTypePointer aKey) : mKey(*aKey) {}
+  nsGenericHashKey(const nsGenericHashKey<T>& aOther) : mKey(aOther.mKey) {}
+
+  KeyType GetKey() const { return mKey; }
+  bool KeyEquals(KeyTypePointer aKey) const { return *aKey == mKey; }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey) { return ::mozilla::Hash(*aKey); }
+  enum { ALLOW_MEMMOVE = true };
+
+private:
+  T mKey;
+};
+
+#endif // nsTHashKeys_h__
diff --git a/xpcom/glue/nsIClassInfoImpl.h b/xpcom/glue/nsIClassInfoImpl.h
new file mode 100644
index 000000000..44303f2be
--- /dev/null
+++ b/xpcom/glue/nsIClassInfoImpl.h
@@ -0,0 +1,179 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsIClassInfoImpl_h__
+#define nsIClassInfoImpl_h__
+
+#include "mozilla/Alignment.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/MacroArgs.h"
+#include "mozilla/MacroForEach.h"
+#include "nsIClassInfo.h"
+#include "nsISupportsImpl.h"
+
+#include <new>
+
+/**
+ * This header file provides macros which help you make your class implement
+ * nsIClassInfo.  Implementing nsIClassInfo is particularly helpful if you have
+ * a C++ class which implements multiple interfaces and which you access from
+ * JavaScript.  If that class implements nsIClassInfo, the JavaScript code
+ * won't have to call QueryInterface on instances of the class; all methods
+ * from all interfaces returned by GetInterfaces() will be available
+ * automagically.
+ *
+ * Here's all you need to do.  Given a class
+ *
+ *   class nsFooBar : public nsIFoo, public nsIBar { };
+ *
+ * you should already have the following nsISupports implementation in its cpp
+ * file:
+ *
+ *   NS_IMPL_ISUPPORTS(nsFooBar, nsIFoo, nsIBar).
+ *
+ * Change this to
+ *
+ *   NS_IMPL_CLASSINFO(nsFooBar, nullptr, 0, NS_FOOBAR_CID)
+ *   NS_IMPL_ISUPPORTS_CI(nsFooBar, nsIFoo, nsIBar)
+ *
+ * If nsFooBar is threadsafe, change the 0 above to nsIClassInfo::THREADSAFE.
+ * If it's a singleton, use nsIClassInfo::SINGLETON.  The full list of flags is
+ * in nsIClassInfo.idl.
+ *
+ * The nullptr parameter is there so you can pass a function for converting
+ * from an XPCOM object to a scriptable helper.  Unless you're doing
+ * specialized JS work, you can probably leave this as nullptr.
+ *
+ * This file also defines the NS_IMPL_QUERY_INTERFACE_CI macro, which you can
+ * use to replace NS_IMPL_QUERY_INTERFACE, if you use that instead of
+ * NS_IMPL_ISUPPORTS.
+ *
+ * That's it!  The rest is gory details.
+ *
+ *
+ * Notice that nsFooBar didn't need to inherit from nsIClassInfo in order to
+ * "implement" it.  However, after adding these macros to nsFooBar, you you can
+ * QueryInterface an instance of nsFooBar to nsIClassInfo.  How can this be?
+ *
+ * The answer lies in the NS_IMPL_ISUPPORTS_CI macro.  It modifies nsFooBar's
+ * QueryInterface implementation such that, if we ask to QI to nsIClassInfo, it
+ * returns a singleton object associated with the class.  (That singleton is
+ * defined by NS_IMPL_CLASSINFO.)  So all nsFooBar instances will return the
+ * same object when QI'ed to nsIClassInfo.  (You can see this in
+ * NS_IMPL_QUERY_CLASSINFO below.)
+ *
+ * This hack breaks XPCOM's rules, since if you take an instance of nsFooBar,
+ * QI it to nsIClassInfo, and then try to QI to nsIFoo, that will fail.  On the
+ * upside, implementing nsIClassInfo doesn't add a vtable pointer to instances
+ * of your class.
+ *
+ * In principal, you can also implement nsIClassInfo by inheriting from the
+ * interface.  But some code expects that when it QI's an object to
+ * nsIClassInfo, it gets back a singleton which isn't attached to any
+ * particular object.  If a class were to implement nsIClassInfo through
+ * inheritance, that code might QI to nsIClassInfo and keep the resulting
+ * object alive, thinking it was only keeping alive the classinfo singleton,
+ * but in fact keeping a whole instance of the class alive.  See, e.g., bug
+ * 658632.
+ *
+ * Unless you specifically need to have a different nsIClassInfo instance for
+ * each instance of your class, you should probably just implement nsIClassInfo
+ * as a singleton.
+ */
+
+class GenericClassInfo : public nsIClassInfo
+{
+public:
+  struct ClassInfoData
+  {
+    // This function pointer uses NS_CALLBACK because it's always set to an
+    // NS_IMETHOD function, which uses __stdcall on Win32.
+    typedef NS_CALLBACK(GetInterfacesProc)(uint32_t* aCountP, nsIID*** aArray);
+    GetInterfacesProc getinterfaces;
+
+    // This function pointer doesn't use NS_CALLBACK because it's always set to
+    // a vanilla function.
+    typedef nsresult (*GetScriptableHelperProc)(nsIXPCScriptable** aHelper);
+    GetScriptableHelperProc getscriptablehelper;
+
+    uint32_t flags;
+    nsCID cid;
+  };
+
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSICLASSINFO
+
+  explicit GenericClassInfo(const ClassInfoData* aData) : mData(aData) {}
+
+private:
+  const ClassInfoData* mData;
+};
+
+#define NS_CLASSINFO_NAME(_class) g##_class##_classInfoGlobal
+#define NS_CI_INTERFACE_GETTER_NAME(_class) _class##_GetInterfacesHelper
+#define NS_DECL_CI_INTERFACE_GETTER(_class)                                   \
+  extern NS_IMETHODIMP NS_CI_INTERFACE_GETTER_NAME(_class)                    \
+     (uint32_t *, nsIID ***);
+
+#define NS_IMPL_CLASSINFO(_class, _getscriptablehelper, _flags, _cid)   \
+  NS_DECL_CI_INTERFACE_GETTER(_class)                                   \
+  static const GenericClassInfo::ClassInfoData k##_class##ClassInfoData = { \
+    NS_CI_INTERFACE_GETTER_NAME(_class),                                \
+    _getscriptablehelper,                                               \
+    _flags | nsIClassInfo::SINGLETON_CLASSINFO,                         \
+    _cid,                                                               \
+  };                                                                    \
+  mozilla::AlignedStorage2<GenericClassInfo> k##_class##ClassInfoDataPlace;   \
+  nsIClassInfo* NS_CLASSINFO_NAME(_class) = nullptr;
+
+#define NS_IMPL_QUERY_CLASSINFO(_class)                                       \
+  if ( aIID.Equals(NS_GET_IID(nsIClassInfo)) ) {                              \
+    if (!NS_CLASSINFO_NAME(_class))                                           \
+      NS_CLASSINFO_NAME(_class) = new (k##_class##ClassInfoDataPlace.addr())  \
+        GenericClassInfo(&k##_class##ClassInfoData);                          \
+    foundInterface = NS_CLASSINFO_NAME(_class);                               \
+  } else
+
+#define NS_CLASSINFO_HELPER_BEGIN(_class, _c)                                 \
+NS_IMETHODIMP                                                                 \
+NS_CI_INTERFACE_GETTER_NAME(_class)(uint32_t *count, nsIID ***array)          \
+{                                                                             \
+    *count = _c;                                                              \
+    *array = (nsIID **)moz_xmalloc(sizeof (nsIID *) * _c);                \
+    uint32_t i = 0;
+
+#define NS_CLASSINFO_HELPER_ENTRY(_interface)                                 \
+    (*array)[i++] = (nsIID*)nsMemory::Clone(&NS_GET_IID(_interface),          \
+                                            sizeof(nsIID));
+
+#define NS_CLASSINFO_HELPER_END                                               \
+    MOZ_ASSERT(i == *count, "Incorrent number of entries");                   \
+    return NS_OK;                                                             \
+}
+
+#define NS_IMPL_CI_INTERFACE_GETTER(aClass, ...)                              \
+  MOZ_STATIC_ASSERT_VALID_ARG_COUNT(__VA_ARGS__);                             \
+  NS_CLASSINFO_HELPER_BEGIN(aClass,                                           \
+                            MOZ_PASTE_PREFIX_AND_ARG_COUNT(/* No prefix */,   \
+                                                           __VA_ARGS__))      \
+    MOZ_FOR_EACH(NS_CLASSINFO_HELPER_ENTRY, (), (__VA_ARGS__))                \
+  NS_CLASSINFO_HELPER_END
+
+#define NS_IMPL_QUERY_INTERFACE_CI(aClass, ...)                               \
+  MOZ_STATIC_ASSERT_VALID_ARG_COUNT(__VA_ARGS__);                             \
+  NS_INTERFACE_MAP_BEGIN(aClass)                                              \
+    MOZ_FOR_EACH(NS_INTERFACE_MAP_ENTRY, (), (__VA_ARGS__))                   \
+    NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, MOZ_ARG_1(__VA_ARGS__))     \
+    NS_IMPL_QUERY_CLASSINFO(aClass)                                           \
+  NS_INTERFACE_MAP_END
+
+#define NS_IMPL_ISUPPORTS_CI(aClass, ...)                                     \
+  NS_IMPL_ADDREF(aClass)                                                      \
+  NS_IMPL_RELEASE(aClass)                                                     \
+  NS_IMPL_QUERY_INTERFACE_CI(aClass, __VA_ARGS__)                             \
+  NS_IMPL_CI_INTERFACE_GETTER(aClass, __VA_ARGS__)
+
+#endif // nsIClassInfoImpl_h__
diff --git a/xpcom/glue/nsID.cpp b/xpcom/glue/nsID.cpp
new file mode 100644
index 000000000..0a73bf6c3
--- /dev/null
+++ b/xpcom/glue/nsID.cpp
@@ -0,0 +1,133 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsID.h"
+#include "nsMemory.h"
+#include "mozilla/Sprintf.h"
+
+void nsID::Clear()
+{
+  m0 = 0;
+  m1 = 0;
+  m2 = 0;
+  for (int i = 0; i < 8; ++i) {
+    m3[i] = 0;
+  }
+}
+
+/**
+ * Multiplies the_int_var with 16 (0x10) and adds the value of the
+ * hexadecimal digit the_char. If it fails it returns false from
+ * the function it's used in.
+ */
+
+#define ADD_HEX_CHAR_TO_INT_OR_RETURN_FALSE(the_char, the_int_var) \
+    the_int_var = (the_int_var << 4) + the_char; \
+    if(the_char >= '0' && the_char <= '9') the_int_var -= '0'; \
+    else if(the_char >= 'a' && the_char <= 'f') the_int_var -= 'a'-10; \
+    else if(the_char >= 'A' && the_char <= 'F') the_int_var -= 'A'-10; \
+    else return false
+
+
+/**
+ * Parses number_of_chars characters from the char_pointer pointer and
+ * puts the number in the dest_variable. The pointer is moved to point
+ * at the first character after the parsed ones. If it fails it returns
+ * false from the function the macro is used in.
+ */
+
+#define PARSE_CHARS_TO_NUM(char_pointer, dest_variable, number_of_chars) \
+  do { int32_t _i=number_of_chars; \
+  dest_variable = 0; \
+  while(_i) { \
+    ADD_HEX_CHAR_TO_INT_OR_RETURN_FALSE(*char_pointer, dest_variable); \
+    char_pointer++; \
+    _i--; \
+  } } while(0)
+
+
+/**
+ * Parses a hyphen from the char_pointer string. If there is no hyphen there
+ * the function returns false from the function it's used in. The
+ * char_pointer is advanced one step.
+ */
+
+#define PARSE_HYPHEN(char_pointer) if (*(char_pointer++) != '-') return false
+
+/*
+ * Turns a {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx} string into
+ * an nsID. It can also handle the old format without the { and }.
+ */
+
+bool
+nsID::Parse(const char* aIDStr)
+{
+  /* Optimized for speed */
+  if (!aIDStr) {
+    return false;
+  }
+
+  bool expectFormat1 = (aIDStr[0] == '{');
+  if (expectFormat1) {
+    ++aIDStr;
+  }
+
+  PARSE_CHARS_TO_NUM(aIDStr, m0, 8);
+  PARSE_HYPHEN(aIDStr);
+  PARSE_CHARS_TO_NUM(aIDStr, m1, 4);
+  PARSE_HYPHEN(aIDStr);
+  PARSE_CHARS_TO_NUM(aIDStr, m2, 4);
+  PARSE_HYPHEN(aIDStr);
+  int i;
+  for (i = 0; i < 2; ++i) {
+    PARSE_CHARS_TO_NUM(aIDStr, m3[i], 2);
+  }
+  PARSE_HYPHEN(aIDStr);
+  while (i < 8) {
+    PARSE_CHARS_TO_NUM(aIDStr, m3[i], 2);
+    i++;
+  }
+
+  return expectFormat1 ? *aIDStr == '}' : true;
+}
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+
+static const char gIDFormat[] =
+  "{%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x}";
+
+/*
+ * Returns an allocated string in {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}
+ * format. The string is allocated with NS_Alloc and should be freed by
+ * the caller.
+ */
+
+char*
+nsID::ToString() const
+{
+  char* res = (char*)NS_Alloc(NSID_LENGTH);
+
+  if (res) {
+    snprintf(res, NSID_LENGTH, gIDFormat,
+             m0, (uint32_t)m1, (uint32_t)m2,
+             (uint32_t)m3[0], (uint32_t)m3[1], (uint32_t)m3[2],
+             (uint32_t)m3[3], (uint32_t)m3[4], (uint32_t)m3[5],
+             (uint32_t)m3[6], (uint32_t)m3[7]);
+  }
+  return res;
+}
+
+void
+nsID::ToProvidedString(char (&aDest)[NSID_LENGTH]) const
+{
+  SprintfLiteral(aDest, gIDFormat,
+                 m0, (uint32_t)m1, (uint32_t)m2,
+                 (uint32_t)m3[0], (uint32_t)m3[1], (uint32_t)m3[2],
+                 (uint32_t)m3[3], (uint32_t)m3[4], (uint32_t)m3[5],
+                 (uint32_t)m3[6], (uint32_t)m3[7]);
+}
+
+#endif // XPCOM_GLUE_AVOID_NSPR
diff --git a/xpcom/glue/nsID.h b/xpcom/glue/nsID.h
new file mode 100644
index 000000000..c04007d4e
--- /dev/null
+++ b/xpcom/glue/nsID.h
@@ -0,0 +1,179 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsID_h__
+#define nsID_h__
+
+#include <string.h>
+
+#include "nscore.h"
+
+#define NSID_LENGTH 39
+
+/**
+ * A "unique identifier". This is modeled after OSF DCE UUIDs.
+ */
+
+struct nsID
+{
+  /**
+   * @name Identifier values
+   */
+
+  //@{
+  uint32_t m0;
+  uint16_t m1;
+  uint16_t m2;
+  uint8_t m3[8];
+  //@}
+
+  /**
+   * @name Methods
+   */
+
+  //@{
+  /**
+   * Ensures everything is zeroed out.
+   */
+  void Clear();
+
+  /**
+   * Equivalency method. Compares this nsID with another.
+   * @return <b>true</b> if they are the same, <b>false</b> if not.
+   */
+
+  inline bool Equals(const nsID& aOther) const
+  {
+    // Unfortunately memcmp isn't faster than this.
+    return
+      (((uint32_t*)&m0)[0] == ((uint32_t*)&aOther.m0)[0]) &&
+      (((uint32_t*)&m0)[1] == ((uint32_t*)&aOther.m0)[1]) &&
+      (((uint32_t*)&m0)[2] == ((uint32_t*)&aOther.m0)[2]) &&
+      (((uint32_t*)&m0)[3] == ((uint32_t*)&aOther.m0)[3]);
+  }
+
+  inline bool operator==(const nsID& aOther) const
+  {
+    return Equals(aOther);
+  }
+
+  /**
+   * nsID Parsing method. Turns a {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}
+   * string into an nsID
+   */
+  bool Parse(const char* aIDStr);
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+  /**
+   * nsID string encoder. Returns an allocated string in
+   * {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx} format. Caller should free string.
+   * YOU SHOULD ONLY USE THIS IF YOU CANNOT USE ToProvidedString() BELOW.
+   */
+  char* ToString() const;
+
+  /**
+   * nsID string encoder. Builds a string in
+   * {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx} format, into a char[NSID_LENGTH]
+   * buffer provided by the caller (for instance, on the stack).
+   */
+  void ToProvidedString(char (&aDest)[NSID_LENGTH]) const;
+
+#endif // XPCOM_GLUE_AVOID_NSPR
+
+  //@}
+};
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+/**
+ * A stack helper class to convert a nsID to a string.  Useful
+ * for printing nsIDs.  For example:
+ *   nsID aID = ...;
+ *   printf("%s", nsIDToCString(aID).get());
+ */
+class nsIDToCString
+{
+public:
+  explicit nsIDToCString(const nsID& aID)
+  {
+    aID.ToProvidedString(mStringBytes);
+  }
+
+  const char *get() const
+  {
+    return mStringBytes;
+  }
+
+protected:
+  char mStringBytes[NSID_LENGTH];
+};
+#endif
+
+/*
+ * Class IDs
+ */
+
+typedef nsID nsCID;
+
+// Define an CID
+#define NS_DEFINE_CID(_name, _cidspec) \
+  const nsCID _name = _cidspec
+
+#define NS_DEFINE_NAMED_CID(_name) \
+  static const nsCID k##_name = _name
+
+#define REFNSCID const nsCID&
+
+/**
+ * An "interface id" which can be used to uniquely identify a given
+ * interface.
+ */
+
+typedef nsID nsIID;
+
+/**
+ * A macro shorthand for <tt>const nsIID&<tt>
+ */
+
+#define REFNSIID const nsIID&
+
+/**
+ * Define an IID
+ * obsolete - do not use this macro
+ */
+
+#define NS_DEFINE_IID(_name, _iidspec) \
+  const nsIID _name = _iidspec
+
+/**
+ * A macro to build the static const IID accessor method. The Dummy
+ * template parameter only exists so that the kIID symbol will be linked
+ * properly (weak symbol on linux, gnu_linkonce on mac, multiple-definitions
+ * merged on windows). Dummy should always be instantiated as "void".
+ */
+
+#define NS_DECLARE_STATIC_IID_ACCESSOR(the_iid)                         \
+  template<typename T, typename U>                                      \
+  struct COMTypeInfo;
+
+#define NS_DEFINE_STATIC_IID_ACCESSOR(the_interface, the_iid)           \
+  template<typename T>                                                  \
+  struct the_interface::COMTypeInfo<the_interface, T> {                 \
+    static const nsIID kIID NS_HIDDEN;                                  \
+  };                                                                    \
+  template<typename T>                                                  \
+  const nsIID the_interface::COMTypeInfo<the_interface, T>::kIID NS_HIDDEN = the_iid;
+
+/**
+ * A macro to build the static const CID accessor method
+ */
+
+#define NS_DEFINE_STATIC_CID_ACCESSOR(the_cid) \
+  static const nsID& GetCID() {static const nsID cid = the_cid; return cid;}
+
+#define NS_GET_IID(T) (T::COMTypeInfo<T, void>::kIID)
+#define NS_GET_TEMPLATE_IID(T) (T::template COMTypeInfo<T, void>::kIID)
+
+#endif
diff --git a/xpcom/glue/nsIInterfaceRequestorUtils.cpp b/xpcom/glue/nsIInterfaceRequestorUtils.cpp
new file mode 100644
index 000000000..8a2dfe3f8
--- /dev/null
+++ b/xpcom/glue/nsIInterfaceRequestorUtils.cpp
@@ -0,0 +1,33 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIInterfaceRequestor.h"
+#include "nsIInterfaceRequestorUtils.h"
+
+nsresult
+nsGetInterface::operator()(const nsIID& aIID, void** aInstancePtr) const
+{
+  nsresult status;
+
+  if (mSource) {
+    nsCOMPtr<nsIInterfaceRequestor> factoryPtr = do_QueryInterface(mSource);
+    if (factoryPtr) {
+      status = factoryPtr->GetInterface(aIID, aInstancePtr);
+    } else {
+      status = NS_ERROR_NO_INTERFACE;
+    }
+  } else {
+    status = NS_ERROR_NULL_POINTER;
+  }
+
+  if (NS_FAILED(status)) {
+    *aInstancePtr = 0;
+  }
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
diff --git a/xpcom/glue/nsIInterfaceRequestorUtils.h b/xpcom/glue/nsIInterfaceRequestorUtils.h
new file mode 100644
index 000000000..718cf387b
--- /dev/null
+++ b/xpcom/glue/nsIInterfaceRequestorUtils.h
@@ -0,0 +1,49 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __nsInterfaceRequestorUtils_h
+#define __nsInterfaceRequestorUtils_h
+
+#include "nsCOMPtr.h"
+
+// a type-safe shortcut for calling the |GetInterface()| member function
+// T must inherit from nsIInterfaceRequestor, but the cast may be ambiguous.
+template<class T, class DestinationType>
+inline nsresult
+CallGetInterface(T* aSource, DestinationType** aDestination)
+{
+  NS_PRECONDITION(aSource, "null parameter");
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return aSource->GetInterface(NS_GET_TEMPLATE_IID(DestinationType),
+                               reinterpret_cast<void**>(aDestination));
+}
+
+class MOZ_STACK_CLASS nsGetInterface final : public nsCOMPtr_helper
+{
+public:
+  nsGetInterface(nsISupports* aSource, nsresult* aError)
+    : mSource(aSource)
+    , mErrorPtr(aError)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID&, void**) const
+    override;
+
+private:
+  nsISupports* MOZ_NON_OWNING_REF mSource;
+  nsresult* mErrorPtr;
+};
+
+inline const nsGetInterface
+do_GetInterface(nsISupports* aSource, nsresult* aError = 0)
+{
+  return nsGetInterface(aSource, aError);
+}
+
+#endif // __nsInterfaceRequestorUtils_h
+
diff --git a/xpcom/glue/nsINIParser.cpp b/xpcom/glue/nsINIParser.cpp
new file mode 100644
index 000000000..53eae7292
--- /dev/null
+++ b/xpcom/glue/nsINIParser.cpp
@@ -0,0 +1,331 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Moz headers (alphabetical)
+#include "nsCRTGlue.h"
+#include "nsError.h"
+#include "nsIFile.h"
+#include "nsINIParser.h"
+#include "mozilla/FileUtils.h" // AutoFILE
+
+// System headers (alphabetical)
+#include <stdio.h>
+#include <stdlib.h>
+#ifdef XP_WIN
+#include <windows.h>
+#endif
+
+#if defined(XP_WIN)
+#define READ_BINARYMODE L"rb"
+#else
+#define READ_BINARYMODE "r"
+#endif
+
+using namespace mozilla;
+
+#ifdef XP_WIN
+inline FILE*
+TS_tfopen(const char* aPath, const wchar_t* aMode)
+{
+  wchar_t wPath[MAX_PATH];
+  MultiByteToWideChar(CP_UTF8, 0, aPath, -1, wPath, MAX_PATH);
+  return _wfopen(wPath, aMode);
+}
+#else
+inline FILE*
+TS_tfopen(const char* aPath, const char* aMode)
+{
+  return fopen(aPath, aMode);
+}
+#endif
+
+// Stack based FILE wrapper to ensure that fclose is called, copied from
+// toolkit/mozapps/update/updater/readstrings.cpp
+
+class AutoFILE
+{
+public:
+  explicit AutoFILE(FILE* aFp = nullptr) : fp_(aFp) {}
+  ~AutoFILE()
+  {
+    if (fp_) {
+      fclose(fp_);
+    }
+  }
+  operator FILE*() { return fp_; }
+  FILE** operator&() { return &fp_; }
+  void operator=(FILE* aFp) { fp_ = aFp; }
+private:
+  FILE* fp_;
+};
+
+nsresult
+nsINIParser::Init(nsIFile* aFile)
+{
+  /* open the file. Don't use OpenANSIFileDesc, because you mustn't
+     pass FILE* across shared library boundaries, which may be using
+     different CRTs */
+
+  AutoFILE fd;
+
+#ifdef XP_WIN
+  nsAutoString path;
+  nsresult rv = aFile->GetPath(path);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  fd = _wfopen(path.get(), READ_BINARYMODE);
+#else
+  nsAutoCString path;
+  aFile->GetNativePath(path);
+
+  fd = fopen(path.get(), READ_BINARYMODE);
+#endif
+
+  if (!fd) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return InitFromFILE(fd);
+}
+
+nsresult
+nsINIParser::Init(const char* aPath)
+{
+  /* open the file */
+  AutoFILE fd(TS_tfopen(aPath, READ_BINARYMODE));
+  if (!fd) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return InitFromFILE(fd);
+}
+
+static const char kNL[] = "\r\n";
+static const char kEquals[] = "=";
+static const char kWhitespace[] = " \t";
+static const char kRBracket[] = "]";
+
+nsresult
+nsINIParser::InitFromFILE(FILE* aFd)
+{
+  /* get file size */
+  if (fseek(aFd, 0, SEEK_END) != 0) {
+    return NS_ERROR_FAILURE;
+  }
+
+  long flen = ftell(aFd);
+  /* zero-sized file, or an error */
+  if (flen <= 0) {
+    return NS_ERROR_FAILURE;
+  }
+
+  /* malloc an internal buf the size of the file */
+  mFileContents = MakeUnique<char[]>(flen + 2);
+  if (!mFileContents) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  /* read the file in one swoop */
+  if (fseek(aFd, 0, SEEK_SET) != 0) {
+    return NS_BASE_STREAM_OSERROR;
+  }
+
+  int rd = fread(mFileContents.get(), sizeof(char), flen, aFd);
+  if (rd != flen) {
+    return NS_BASE_STREAM_OSERROR;
+  }
+
+  // We write a UTF16 null so that the file is easier to convert to UTF8
+  mFileContents[flen] = mFileContents[flen + 1] = '\0';
+
+  char* buffer = &mFileContents[0];
+
+  if (flen >= 3 &&
+      mFileContents[0] == '\xEF' &&
+      mFileContents[1] == '\xBB' &&
+      mFileContents[2] == '\xBF') {
+    // Someone set us up the Utf-8 BOM
+    // This case is easy, since we assume that BOM-less
+    // files are Utf-8 anyway.  Just skip the BOM and process as usual.
+    buffer = &mFileContents[3];
+  }
+
+#ifdef XP_WIN
+  if (flen >= 2 &&
+      mFileContents[0] == '\xFF' &&
+      mFileContents[1] == '\xFE') {
+    // Someone set us up the Utf-16LE BOM
+    buffer = &mFileContents[2];
+    // Get the size required for our Utf8 buffer
+    flen = WideCharToMultiByte(CP_UTF8,
+                               0,
+                               reinterpret_cast<LPWSTR>(buffer),
+                               -1,
+                               nullptr,
+                               0,
+                               nullptr,
+                               nullptr);
+    if (flen == 0) {
+      return NS_ERROR_FAILURE;
+    }
+
+    UniquePtr<char[]> utf8Buffer(new char[flen]);
+    if (WideCharToMultiByte(CP_UTF8, 0, reinterpret_cast<LPWSTR>(buffer), -1,
+                            utf8Buffer.get(), flen, nullptr, nullptr) == 0) {
+      return NS_ERROR_FAILURE;
+    }
+    mFileContents = Move(utf8Buffer);
+    buffer = mFileContents.get();
+  }
+#endif
+
+  char* currSection = nullptr;
+
+  // outer loop tokenizes into lines
+  while (char* token = NS_strtok(kNL, &buffer)) {
+    if (token[0] == '#' || token[0] == ';') { // it's a comment
+      continue;
+    }
+
+    token = (char*)NS_strspnp(kWhitespace, token);
+    if (!*token) { // empty line
+      continue;
+    }
+
+    if (token[0] == '[') { // section header!
+      ++token;
+      currSection = token;
+
+      char* rb = NS_strtok(kRBracket, &token);
+      if (!rb || NS_strtok(kWhitespace, &token)) {
+        // there's either an unclosed [Section or a [Section]Moretext!
+        // we could frankly decide that this INI file is malformed right
+        // here and stop, but we won't... keep going, looking for
+        // a well-formed [section] to continue working with
+        currSection = nullptr;
+      }
+
+      continue;
+    }
+
+    if (!currSection) {
+      // If we haven't found a section header (or we found a malformed
+      // section header), don't bother parsing this line.
+      continue;
+    }
+
+    char* key = token;
+    char* e = NS_strtok(kEquals, &token);
+    if (!e || !token) {
+      continue;
+    }
+
+    INIValue* v;
+    if (!mSections.Get(currSection, &v)) {
+      v = new INIValue(key, token);
+      if (!v) {
+        return NS_ERROR_OUT_OF_MEMORY;
+      }
+
+      mSections.Put(currSection, v);
+      continue;
+    }
+
+    // Check whether this key has already been specified; overwrite
+    // if so, or append if not.
+    while (v) {
+      if (!strcmp(key, v->key)) {
+        v->value = token;
+        break;
+      }
+      if (!v->next) {
+        v->next = MakeUnique<INIValue>(key, token);
+        if (!v->next) {
+          return NS_ERROR_OUT_OF_MEMORY;
+        }
+        break;
+      }
+      v = v->next.get();
+    }
+    NS_ASSERTION(v, "v should never be null coming out of this loop");
+  }
+
+  return NS_OK;
+}
+
+nsresult
+nsINIParser::GetString(const char* aSection, const char* aKey,
+                       nsACString& aResult)
+{
+  INIValue* val;
+  mSections.Get(aSection, &val);
+
+  while (val) {
+    if (strcmp(val->key, aKey) == 0) {
+      aResult.Assign(val->value);
+      return NS_OK;
+    }
+
+    val = val->next.get();
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+nsresult
+nsINIParser::GetString(const char* aSection, const char* aKey,
+                       char* aResult, uint32_t aResultLen)
+{
+  INIValue* val;
+  mSections.Get(aSection, &val);
+
+  while (val) {
+    if (strcmp(val->key, aKey) == 0) {
+      strncpy(aResult, val->value, aResultLen);
+      aResult[aResultLen - 1] = '\0';
+      if (strlen(val->value) >= aResultLen) {
+        return NS_ERROR_LOSS_OF_SIGNIFICANT_DATA;
+      }
+
+      return NS_OK;
+    }
+
+    val = val->next.get();
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+nsresult
+nsINIParser::GetSections(INISectionCallback aCB, void* aClosure)
+{
+  for (auto iter = mSections.Iter(); !iter.Done(); iter.Next()) {
+    if (!aCB(iter.Key(), aClosure)) {
+      break;
+    }
+  }
+  return NS_OK;
+}
+
+nsresult
+nsINIParser::GetStrings(const char* aSection,
+                        INIStringCallback aCB, void* aClosure)
+{
+  INIValue* val;
+
+  for (mSections.Get(aSection, &val);
+       val;
+       val = val->next.get()) {
+
+    if (!aCB(val->key, val->value, aClosure)) {
+      return NS_OK;
+    }
+  }
+
+  return NS_OK;
+}
diff --git a/xpcom/glue/nsINIParser.h b/xpcom/glue/nsINIParser.h
new file mode 100644
index 000000000..d0f553d49
--- /dev/null
+++ b/xpcom/glue/nsINIParser.h
@@ -0,0 +1,118 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// This file was shamelessly copied from mozilla/xpinstall/wizard/unix/src2
+
+#ifndef nsINIParser_h__
+#define nsINIParser_h__
+
+#ifdef MOZILLA_INTERNAL_API
+#define nsINIParser nsINIParser_internal
+#endif
+
+#include "nscore.h"
+#include "nsClassHashtable.h"
+#include "mozilla/UniquePtr.h"
+
+#include <stdio.h>
+
+class nsIFile;
+
+class nsINIParser
+{
+public:
+  nsINIParser() {}
+  ~nsINIParser() {}
+
+  /**
+   * Initialize the INIParser with a nsIFile. If this method fails, no
+   * other methods should be called. This method reads and parses the file,
+   * the class does not hold a file handle open. An instance must only be
+   * initialized once.
+   */
+  nsresult Init(nsIFile* aFile);
+
+  /**
+   * Initialize the INIParser with a file path. If this method fails, no
+   * other methods should be called. This method reads and parses the file,
+   * the class does not hold a file handle open. An instance must only
+   * be initialized once.
+   */
+  nsresult Init(const char* aPath);
+
+  /**
+   * Callback for GetSections
+   * @return false to stop enumeration, or true to continue.
+   */
+  typedef bool (*INISectionCallback)(const char* aSection, void* aClosure);
+
+  /**
+   * Enumerate the sections within the INI file.
+   */
+  nsresult GetSections(INISectionCallback aCB, void* aClosure);
+
+  /**
+   * Callback for GetStrings
+   * @return false to stop enumeration, or true to continue
+   */
+  typedef bool (*INIStringCallback)(const char* aString, const char* aValue,
+                                    void* aClosure);
+
+  /**
+   * Enumerate the strings within a section. If the section does
+   * not exist, this function will silently return.
+   */
+  nsresult GetStrings(const char* aSection,
+                      INIStringCallback aCB, void* aClosure);
+
+  /**
+   * Get the value of the specified key in the specified section
+   * of the INI file represented by this instance.
+   *
+   * @param aSection      section name
+   * @param aKey          key name
+   * @param aResult       the value found
+   * @throws NS_ERROR_FAILURE if the specified section/key could not be
+   *                          found.
+   */
+  nsresult GetString(const char* aSection, const char* aKey,
+                     nsACString& aResult);
+
+  /**
+   * Alternate signature of GetString that uses a pre-allocated buffer
+   * instead of a nsACString (for use in the standalone glue before
+   * the glue is initialized).
+   *
+   * @throws NS_ERROR_LOSS_OF_SIGNIFICANT_DATA if the aResult buffer is not
+   *         large enough for the data. aResult will be filled with as
+   *         much data as possible.
+   *
+   * @see GetString [1]
+   */
+  nsresult GetString(const char* aSection, const char* aKey,
+                     char* aResult, uint32_t aResultLen);
+
+private:
+  struct INIValue
+  {
+    INIValue(const char* aKey, const char* aValue)
+      : key(aKey)
+      , value(aValue)
+    {
+    }
+
+    const char* key;
+    const char* value;
+    mozilla::UniquePtr<INIValue> next;
+  };
+
+  nsClassHashtable<nsDepCharHashKey, INIValue> mSections;
+  mozilla::UniquePtr<char[]> mFileContents;
+
+  nsresult InitFromFILE(FILE* aFd);
+};
+
+#endif /* nsINIParser_h__ */
diff --git a/xpcom/glue/nsISupportsImpl.cpp b/xpcom/glue/nsISupportsImpl.cpp
new file mode 100644
index 000000000..c60c0bfa7
--- /dev/null
+++ b/xpcom/glue/nsISupportsImpl.cpp
@@ -0,0 +1,27 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupportsImpl.h"
+
+nsresult NS_FASTCALL
+NS_TableDrivenQI(void* aThis, REFNSIID aIID, void** aInstancePtr,
+                 const QITableEntry* aEntries)
+{
+  do {
+    if (aIID.Equals(*aEntries->iid)) {
+      nsISupports* r = reinterpret_cast<nsISupports*>(
+        reinterpret_cast<char*>(aThis) + aEntries->offset);
+      NS_ADDREF(r);
+      *aInstancePtr = r;
+      return NS_OK;
+    }
+
+    ++aEntries;
+  } while (aEntries->iid);
+
+  *aInstancePtr = nullptr;
+  return NS_ERROR_NO_INTERFACE;
+}
diff --git a/xpcom/glue/nsISupportsImpl.h b/xpcom/glue/nsISupportsImpl.h
new file mode 100644
index 000000000..26db3c525
--- /dev/null
+++ b/xpcom/glue/nsISupportsImpl.h
@@ -0,0 +1,1090 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+// IWYU pragma: private, include "nsISupports.h"
+
+
+#ifndef nsISupportsImpl_h__
+#define nsISupportsImpl_h__
+
+#include "nscore.h"
+#include "nsISupportsBase.h"
+#include "nsISupportsUtils.h"
+
+
+#if !defined(XPCOM_GLUE_AVOID_NSPR)
+#include "prthread.h" /* needed for thread-safety checks */
+#endif // !XPCOM_GLUE_AVOID_NSPR
+
+#include "nsDebug.h"
+#include "nsXPCOM.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Compiler.h"
+#include "mozilla/Likely.h"
+#include "mozilla/MacroArgs.h"
+#include "mozilla/MacroForEach.h"
+#include "mozilla/TypeTraits.h"
+
+#define MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(X) \
+  static_assert(!mozilla::IsDestructible<X>::value, \
+                "Reference-counted class " #X " should not have a public destructor. " \
+                "Make this class's destructor non-public");
+
+inline nsISupports*
+ToSupports(nsISupports* aSupports)
+{
+  return aSupports;
+}
+
+inline nsISupports*
+ToCanonicalSupports(nsISupports* aSupports)
+{
+  return nullptr;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Macros to help detect thread-safety:
+
+#ifdef MOZ_THREAD_SAFETY_OWNERSHIP_CHECKS_SUPPORTED
+
+class nsAutoOwningThread
+{
+public:
+  nsAutoOwningThread() { mThread = PR_GetCurrentThread(); }
+  void* GetThread() const { return mThread; }
+
+private:
+  void* mThread;
+};
+
+#define NS_DECL_OWNINGTHREAD            nsAutoOwningThread _mOwningThread;
+#define NS_ASSERT_OWNINGTHREAD_AGGREGATE(agg, _class) \
+  NS_CheckThreadSafe(agg->_mOwningThread.GetThread(), #_class " not thread-safe")
+#define NS_ASSERT_OWNINGTHREAD(_class) NS_ASSERT_OWNINGTHREAD_AGGREGATE(this, _class)
+#else // !DEBUG && !(NIGHTLY_BUILD && !MOZ_PROFILING)
+
+#define NS_DECL_OWNINGTHREAD            /* nothing */
+#define NS_ASSERT_OWNINGTHREAD_AGGREGATE(agg, _class) ((void)0)
+#define NS_ASSERT_OWNINGTHREAD(_class)  ((void)0)
+
+#endif // DEBUG || (NIGHTLY_BUILD && !MOZ_PROFILING)
+
+
+// Macros for reference-count and constructor logging
+
+#if defined(NS_BUILD_REFCNT_LOGGING)
+
+#define NS_LOG_ADDREF(_p, _rc, _type, _size) \
+  NS_LogAddRef((_p), (_rc), (_type), (uint32_t) (_size))
+
+#define NS_LOG_RELEASE(_p, _rc, _type) \
+  NS_LogRelease((_p), (_rc), (_type))
+
+#include "mozilla/TypeTraits.h"
+#define MOZ_ASSERT_CLASSNAME(_type)                         \
+  static_assert(mozilla::IsClass<_type>::value,             \
+                "Token '" #_type "' is not a class type.")
+
+// Note that the following constructor/destructor logging macros are redundant
+// for refcounted objects that log via the NS_LOG_ADDREF/NS_LOG_RELEASE macros.
+// Refcount logging is preferred.
+#define MOZ_COUNT_CTOR(_type)                                 \
+do {                                                          \
+  MOZ_ASSERT_CLASSNAME(_type);                                \
+  NS_LogCtor((void*)this, #_type, sizeof(*this));             \
+} while (0)
+
+#define MOZ_COUNT_CTOR_INHERITED(_type, _base)                    \
+do {                                                              \
+  MOZ_ASSERT_CLASSNAME(_type);                                    \
+  MOZ_ASSERT_CLASSNAME(_base);                                    \
+  NS_LogCtor((void*)this, #_type, sizeof(*this) - sizeof(_base)); \
+} while (0)
+
+#define MOZ_LOG_CTOR(_ptr, _name, _size) \
+do {                                     \
+  NS_LogCtor((void*)_ptr, _name, _size); \
+} while (0)
+
+#define MOZ_COUNT_DTOR(_type)                                 \
+do {                                                          \
+  MOZ_ASSERT_CLASSNAME(_type);                                \
+  NS_LogDtor((void*)this, #_type, sizeof(*this));             \
+} while (0)
+
+#define MOZ_COUNT_DTOR_INHERITED(_type, _base)                    \
+do {                                                              \
+  MOZ_ASSERT_CLASSNAME(_type);                                    \
+  MOZ_ASSERT_CLASSNAME(_base);                                    \
+  NS_LogDtor((void*)this, #_type, sizeof(*this) - sizeof(_base)); \
+} while (0)
+
+#define MOZ_LOG_DTOR(_ptr, _name, _size) \
+do {                                     \
+  NS_LogDtor((void*)_ptr, _name, _size); \
+} while (0)
+
+/* nsCOMPtr.h allows these macros to be defined by clients
+ * These logging functions require dynamic_cast<void*>, so they don't
+ * do anything useful if we don't have dynamic_cast<void*>.
+ * Note: The explicit comparison to nullptr is needed to avoid warnings
+ *       when _p is a nullptr itself. */
+#define NSCAP_LOG_ASSIGNMENT(_c, _p)                                \
+  if (_p != nullptr)                                                \
+    NS_LogCOMPtrAddRef((_c),static_cast<nsISupports*>(_p))
+
+#define NSCAP_LOG_RELEASE(_c, _p)                                   \
+  if (_p)                                                           \
+    NS_LogCOMPtrRelease((_c), static_cast<nsISupports*>(_p))
+
+#else /* !NS_BUILD_REFCNT_LOGGING */
+
+#define NS_LOG_ADDREF(_p, _rc, _type, _size)
+#define NS_LOG_RELEASE(_p, _rc, _type)
+#define MOZ_COUNT_CTOR(_type)
+#define MOZ_COUNT_CTOR_INHERITED(_type, _base)
+#define MOZ_LOG_CTOR(_ptr, _name, _size)
+#define MOZ_COUNT_DTOR(_type)
+#define MOZ_COUNT_DTOR_INHERITED(_type, _base)
+#define MOZ_LOG_DTOR(_ptr, _name, _size)
+
+#endif /* NS_BUILD_REFCNT_LOGGING */
+
+
+// Support for ISupports classes which interact with cycle collector.
+
+#define NS_NUMBER_OF_FLAGS_IN_REFCNT 2
+#define NS_IN_PURPLE_BUFFER (1 << 0)
+#define NS_IS_PURPLE (1 << 1)
+#define NS_REFCOUNT_CHANGE (1 << NS_NUMBER_OF_FLAGS_IN_REFCNT)
+#define NS_REFCOUNT_VALUE(_val) (_val >> NS_NUMBER_OF_FLAGS_IN_REFCNT)
+
+class nsCycleCollectingAutoRefCnt
+{
+public:
+  nsCycleCollectingAutoRefCnt() : mRefCntAndFlags(0) {}
+
+  explicit nsCycleCollectingAutoRefCnt(uintptr_t aValue)
+    : mRefCntAndFlags(aValue << NS_NUMBER_OF_FLAGS_IN_REFCNT)
+  {
+  }
+
+  nsCycleCollectingAutoRefCnt(const nsCycleCollectingAutoRefCnt&) = delete;
+  void operator=(const nsCycleCollectingAutoRefCnt&) = delete;
+
+  MOZ_ALWAYS_INLINE uintptr_t incr(nsISupports* aOwner)
+  {
+    return incr(aOwner, nullptr);
+  }
+
+  MOZ_ALWAYS_INLINE uintptr_t incr(void* aOwner,
+                                   nsCycleCollectionParticipant* aCp)
+  {
+    mRefCntAndFlags += NS_REFCOUNT_CHANGE;
+    mRefCntAndFlags &= ~NS_IS_PURPLE;
+    // For incremental cycle collection, use the purple buffer to track objects
+    // that have been AddRef'd.
+    if (!IsInPurpleBuffer()) {
+      mRefCntAndFlags |= NS_IN_PURPLE_BUFFER;
+      // Refcount isn't zero, so Suspect won't delete anything.
+      MOZ_ASSERT(get() > 0);
+      NS_CycleCollectorSuspect3(aOwner, aCp, this, nullptr);
+    }
+    return NS_REFCOUNT_VALUE(mRefCntAndFlags);
+  }
+
+  MOZ_ALWAYS_INLINE void stabilizeForDeletion()
+  {
+    // Set refcnt to 1 and mark us to be in the purple buffer.
+    // This way decr won't call suspect again.
+    mRefCntAndFlags = NS_REFCOUNT_CHANGE | NS_IN_PURPLE_BUFFER;
+  }
+
+  MOZ_ALWAYS_INLINE uintptr_t decr(nsISupports* aOwner,
+                                   bool* aShouldDelete = nullptr)
+  {
+    return decr(aOwner, nullptr, aShouldDelete);
+  }
+
+  MOZ_ALWAYS_INLINE uintptr_t decr(void* aOwner,
+                                   nsCycleCollectionParticipant* aCp,
+                                   bool* aShouldDelete = nullptr)
+  {
+    MOZ_ASSERT(get() > 0);
+    if (!IsInPurpleBuffer()) {
+      mRefCntAndFlags -= NS_REFCOUNT_CHANGE;
+      mRefCntAndFlags |= (NS_IN_PURPLE_BUFFER | NS_IS_PURPLE);
+      uintptr_t retval = NS_REFCOUNT_VALUE(mRefCntAndFlags);
+      // Suspect may delete 'aOwner' and 'this'!
+      NS_CycleCollectorSuspect3(aOwner, aCp, this, aShouldDelete);
+      return retval;
+    }
+    mRefCntAndFlags -= NS_REFCOUNT_CHANGE;
+    mRefCntAndFlags |= (NS_IN_PURPLE_BUFFER | NS_IS_PURPLE);
+    return NS_REFCOUNT_VALUE(mRefCntAndFlags);
+  }
+
+  MOZ_ALWAYS_INLINE void RemovePurple()
+  {
+    MOZ_ASSERT(IsPurple(), "must be purple");
+    mRefCntAndFlags &= ~NS_IS_PURPLE;
+  }
+
+  MOZ_ALWAYS_INLINE void RemoveFromPurpleBuffer()
+  {
+    MOZ_ASSERT(IsInPurpleBuffer());
+    mRefCntAndFlags &= ~(NS_IS_PURPLE | NS_IN_PURPLE_BUFFER);
+  }
+
+  MOZ_ALWAYS_INLINE bool IsPurple() const
+  {
+    return !!(mRefCntAndFlags & NS_IS_PURPLE);
+  }
+
+  MOZ_ALWAYS_INLINE bool IsInPurpleBuffer() const
+  {
+    return !!(mRefCntAndFlags & NS_IN_PURPLE_BUFFER);
+  }
+
+  MOZ_ALWAYS_INLINE nsrefcnt get() const
+  {
+    return NS_REFCOUNT_VALUE(mRefCntAndFlags);
+  }
+
+  MOZ_ALWAYS_INLINE operator nsrefcnt() const
+  {
+    return get();
+  }
+
+private:
+  uintptr_t mRefCntAndFlags;
+};
+
+class nsAutoRefCnt
+{
+public:
+  nsAutoRefCnt() : mValue(0) {}
+  explicit nsAutoRefCnt(nsrefcnt aValue) : mValue(aValue) {}
+
+  nsAutoRefCnt(const nsAutoRefCnt&) = delete;
+  void operator=(const nsAutoRefCnt&) = delete;
+
+  // only support prefix increment/decrement
+  nsrefcnt operator++() { return ++mValue; }
+  nsrefcnt operator--() { return --mValue; }
+
+  nsrefcnt operator=(nsrefcnt aValue) { return (mValue = aValue); }
+  operator nsrefcnt() const { return mValue; }
+  nsrefcnt get() const { return mValue; }
+
+  static const bool isThreadSafe = false;
+private:
+  nsrefcnt operator++(int) = delete;
+  nsrefcnt operator--(int) = delete;
+  nsrefcnt mValue;
+};
+
+namespace mozilla {
+class ThreadSafeAutoRefCnt
+{
+public:
+  ThreadSafeAutoRefCnt() : mValue(0) {}
+  explicit ThreadSafeAutoRefCnt(nsrefcnt aValue) : mValue(aValue) {}
+
+  ThreadSafeAutoRefCnt(const ThreadSafeAutoRefCnt&) = delete;
+  void operator=(const ThreadSafeAutoRefCnt&) = delete;
+
+  // only support prefix increment/decrement
+  MOZ_ALWAYS_INLINE nsrefcnt operator++() { return ++mValue; }
+  MOZ_ALWAYS_INLINE nsrefcnt operator--() { return --mValue; }
+
+  MOZ_ALWAYS_INLINE nsrefcnt operator=(nsrefcnt aValue)
+  {
+    return (mValue = aValue);
+  }
+  MOZ_ALWAYS_INLINE operator nsrefcnt() const { return mValue; }
+  MOZ_ALWAYS_INLINE nsrefcnt get() const { return mValue; }
+
+  static const bool isThreadSafe = true;
+private:
+  nsrefcnt operator++(int) = delete;
+  nsrefcnt operator--(int) = delete;
+  // In theory, RelaseAcquire consistency (but no weaker) is sufficient for
+  // the counter. Making it weaker could speed up builds on ARM (but not x86),
+  // but could break pre-existing code that assumes sequential consistency.
+  Atomic<nsrefcnt> mValue;
+};
+} // namespace mozilla
+
+///////////////////////////////////////////////////////////////////////////////
+
+/**
+ * Declare the reference count variable and the implementations of the
+ * AddRef and QueryInterface methods.
+ */
+
+#define NS_DECL_ISUPPORTS                                                     \
+public:                                                                       \
+  NS_IMETHOD QueryInterface(REFNSIID aIID,                                    \
+                            void** aInstancePtr) override;                    \
+  NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override;                 \
+  NS_IMETHOD_(MozExternalRefCountType) Release(void) override;                \
+  typedef mozilla::FalseType HasThreadSafeRefCnt;                             \
+protected:                                                                    \
+  nsAutoRefCnt mRefCnt;                                                       \
+  NS_DECL_OWNINGTHREAD                                                        \
+public:
+
+#define NS_DECL_THREADSAFE_ISUPPORTS                                          \
+public:                                                                       \
+  NS_IMETHOD QueryInterface(REFNSIID aIID,                                    \
+                            void** aInstancePtr) override;                    \
+  NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override;                 \
+  NS_IMETHOD_(MozExternalRefCountType) Release(void) override;                \
+  typedef mozilla::TrueType HasThreadSafeRefCnt;                              \
+protected:                                                                    \
+  ::mozilla::ThreadSafeAutoRefCnt mRefCnt;                                    \
+  NS_DECL_OWNINGTHREAD                                                        \
+public:
+
+#define NS_DECL_CYCLE_COLLECTING_ISUPPORTS                                    \
+public:                                                                       \
+  NS_IMETHOD QueryInterface(REFNSIID aIID,                                    \
+                            void** aInstancePtr) override;                    \
+  NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override;                 \
+  NS_IMETHOD_(MozExternalRefCountType) Release(void) override;                \
+  NS_IMETHOD_(void) DeleteCycleCollectable(void);                             \
+  typedef mozilla::FalseType HasThreadSafeRefCnt;                             \
+protected:                                                                    \
+  nsCycleCollectingAutoRefCnt mRefCnt;                                        \
+  NS_DECL_OWNINGTHREAD                                                        \
+public:
+
+
+///////////////////////////////////////////////////////////////////////////////
+
+/*
+ * Implementation of AddRef and Release for non-nsISupports (ie "native")
+ * cycle-collected classes that use the purple buffer to avoid leaks.
+ */
+
+#define NS_IMPL_CC_NATIVE_ADDREF_BODY(_class)                                 \
+    MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                                \
+    MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");                      \
+    NS_ASSERT_OWNINGTHREAD(_class);                                           \
+    nsrefcnt count =                                                          \
+      mRefCnt.incr(static_cast<void*>(this),                                  \
+                   _class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant()); \
+    NS_LOG_ADDREF(this, count, #_class, sizeof(*this));                       \
+    return count;
+
+#define NS_IMPL_CC_NATIVE_RELEASE_BODY(_class)                                \
+    MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                          \
+    NS_ASSERT_OWNINGTHREAD(_class);                                           \
+    nsrefcnt count =                                                          \
+      mRefCnt.decr(static_cast<void*>(this),                                  \
+                   _class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant()); \
+    NS_LOG_RELEASE(this, count, #_class);                                     \
+    return count;
+
+#define NS_IMPL_CYCLE_COLLECTING_NATIVE_ADDREF(_class)                        \
+NS_METHOD_(MozExternalRefCountType) _class::AddRef(void)                      \
+{                                                                             \
+  NS_IMPL_CC_NATIVE_ADDREF_BODY(_class)                                       \
+}
+
+#define NS_IMPL_CYCLE_COLLECTING_NATIVE_RELEASE_WITH_LAST_RELEASE(_class, _last) \
+NS_METHOD_(MozExternalRefCountType) _class::Release(void)                        \
+{                                                                                \
+    MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                             \
+    NS_ASSERT_OWNINGTHREAD(_class);                                              \
+    bool shouldDelete = false;                                                   \
+    nsrefcnt count =                                                             \
+      mRefCnt.decr(static_cast<void*>(this),                                     \
+                   _class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant(),     \
+                   &shouldDelete);                                               \
+    NS_LOG_RELEASE(this, count, #_class);                                        \
+    if (count == 0) {                                                            \
+        mRefCnt.incr(static_cast<void*>(this),                                   \
+                     _class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant());  \
+        _last;                                                                   \
+        mRefCnt.decr(static_cast<void*>(this),                                   \
+                     _class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant());  \
+        if (shouldDelete) {                                                      \
+            mRefCnt.stabilizeForDeletion();                                      \
+            DeleteCycleCollectable();                                            \
+        }                                                                        \
+    }                                                                            \
+    return count;                                                                \
+}
+
+#define NS_IMPL_CYCLE_COLLECTING_NATIVE_RELEASE(_class)                       \
+NS_METHOD_(MozExternalRefCountType) _class::Release(void)                     \
+{                                                                             \
+  NS_IMPL_CC_NATIVE_RELEASE_BODY(_class)                                      \
+}
+
+#define NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(_class)            \
+public:                                                                       \
+  NS_METHOD_(MozExternalRefCountType) AddRef(void) {                          \
+    NS_IMPL_CC_NATIVE_ADDREF_BODY(_class)                                     \
+  }                                                                           \
+  NS_METHOD_(MozExternalRefCountType) Release(void) {                         \
+    NS_IMPL_CC_NATIVE_RELEASE_BODY(_class)                                    \
+  }                                                                           \
+  typedef mozilla::FalseType HasThreadSafeRefCnt;                             \
+protected:                                                                    \
+  nsCycleCollectingAutoRefCnt mRefCnt;                                        \
+  NS_DECL_OWNINGTHREAD                                                        \
+public:
+
+
+///////////////////////////////////////////////////////////////////////////////
+
+/**
+ * Use this macro to declare and implement the AddRef & Release methods for a
+ * given non-XPCOM <i>_class</i>.
+ *
+ * @param _class The name of the class implementing the method
+ * @param _destroy A statement that is executed when the object's
+ *   refcount drops to zero.
+ * @param optional override Mark the AddRef & Release methods as overrides.
+ */
+#define NS_INLINE_DECL_REFCOUNTING_WITH_DESTROY(_class, _destroy, ...)        \
+public:                                                                       \
+  NS_METHOD_(MozExternalRefCountType) AddRef(void) __VA_ARGS__ {              \
+    MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                                \
+    MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");                      \
+    NS_ASSERT_OWNINGTHREAD(_class);                                           \
+    ++mRefCnt;                                                                \
+    NS_LOG_ADDREF(this, mRefCnt, #_class, sizeof(*this));                     \
+    return mRefCnt;                                                           \
+  }                                                                           \
+  NS_METHOD_(MozExternalRefCountType) Release(void) __VA_ARGS__ {             \
+    MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                          \
+    NS_ASSERT_OWNINGTHREAD(_class);                                           \
+    --mRefCnt;                                                                \
+    NS_LOG_RELEASE(this, mRefCnt, #_class);                                   \
+    if (mRefCnt == 0) {                                                       \
+      mRefCnt = 1; /* stabilize */                                            \
+      _destroy;                                                               \
+      return 0;                                                               \
+    }                                                                         \
+    return mRefCnt;                                                           \
+  }                                                                           \
+  typedef mozilla::FalseType HasThreadSafeRefCnt;                             \
+protected:                                                                    \
+  nsAutoRefCnt mRefCnt;                                                       \
+  NS_DECL_OWNINGTHREAD                                                        \
+public:
+
+/**
+ * Use this macro to declare and implement the AddRef & Release methods for a
+ * given non-XPCOM <i>_class</i>.
+ *
+ * @param _class The name of the class implementing the method
+ * @param optional override Mark the AddRef & Release methods as overrides.
+ */
+#define NS_INLINE_DECL_REFCOUNTING(_class, ...)                               \
+  NS_INLINE_DECL_REFCOUNTING_WITH_DESTROY(_class, delete(this), __VA_ARGS__)
+
+#define NS_INLINE_DECL_THREADSAFE_REFCOUNTING_META(_class, _decl, ...)        \
+public:                                                                       \
+  _decl(MozExternalRefCountType) AddRef(void) __VA_ARGS__ {                   \
+    MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                                \
+    MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");                      \
+    nsrefcnt count = ++mRefCnt;                                               \
+    NS_LOG_ADDREF(this, count, #_class, sizeof(*this));                       \
+    return (nsrefcnt) count;                                                  \
+  }                                                                           \
+  _decl(MozExternalRefCountType) Release(void) __VA_ARGS__ {                  \
+    MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                          \
+    nsrefcnt count = --mRefCnt;                                               \
+    NS_LOG_RELEASE(this, count, #_class);                                     \
+    if (count == 0) {                                                         \
+      delete (this);                                                          \
+      return 0;                                                               \
+    }                                                                         \
+    return count;                                                             \
+  }                                                                           \
+  typedef mozilla::TrueType HasThreadSafeRefCnt;                              \
+protected:                                                                    \
+  ::mozilla::ThreadSafeAutoRefCnt mRefCnt;                                    \
+public:
+
+/**
+ * Use this macro to declare and implement the AddRef & Release methods for a
+ * given non-XPCOM <i>_class</i> in a threadsafe manner.
+ *
+ * DOES NOT DO REFCOUNT STABILIZATION!
+ *
+ * @param _class The name of the class implementing the method
+ */
+#define NS_INLINE_DECL_THREADSAFE_REFCOUNTING(_class, ...)                    \
+NS_INLINE_DECL_THREADSAFE_REFCOUNTING_META(_class, NS_METHOD_, __VA_ARGS__)
+
+/**
+ * Like NS_INLINE_DECL_THREADSAFE_REFCOUNTING with AddRef & Release declared
+ * virtual.
+ */
+#define NS_INLINE_DECL_THREADSAFE_VIRTUAL_REFCOUNTING(_class, ...)            \
+NS_INLINE_DECL_THREADSAFE_REFCOUNTING_META(_class, NS_IMETHOD_, __VA_ARGS__)
+
+/**
+ * Use this macro to implement the AddRef method for a given <i>_class</i>
+ * @param _class The name of the class implementing the method
+ */
+#define NS_IMPL_ADDREF(_class)                                                \
+NS_IMETHODIMP_(MozExternalRefCountType) _class::AddRef(void)                  \
+{                                                                             \
+  MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                                  \
+  MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");                        \
+  if (!mRefCnt.isThreadSafe)                                                  \
+    NS_ASSERT_OWNINGTHREAD(_class);                                           \
+  nsrefcnt count = ++mRefCnt;                                                 \
+  NS_LOG_ADDREF(this, count, #_class, sizeof(*this));                         \
+  return count;                                                               \
+}
+
+/**
+ * Use this macro to implement the AddRef method for a given <i>_class</i>
+ * implemented as a wholly owned aggregated object intended to implement
+ * interface(s) for its owner
+ * @param _class The name of the class implementing the method
+ * @param _aggregator the owning/containing object
+ */
+#define NS_IMPL_ADDREF_USING_AGGREGATOR(_class, _aggregator)                  \
+NS_IMETHODIMP_(MozExternalRefCountType) _class::AddRef(void)                  \
+{                                                                             \
+  MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                                  \
+  NS_PRECONDITION(_aggregator, "null aggregator");                            \
+  return (_aggregator)->AddRef();                                             \
+}
+
+/**
+ * Use this macro to implement the Release method for a given
+ * <i>_class</i>.
+ * @param _class The name of the class implementing the method
+ * @param _destroy A statement that is executed when the object's
+ *   refcount drops to zero.
+ *
+ * For example,
+ *
+ *   NS_IMPL_RELEASE_WITH_DESTROY(Foo, Destroy(this))
+ *
+ * will cause
+ *
+ *   Destroy(this);
+ *
+ * to be invoked when the object's refcount drops to zero. This
+ * allows for arbitrary teardown activity to occur (e.g., deallocation
+ * of object allocated with placement new).
+ */
+#define NS_IMPL_RELEASE_WITH_DESTROY(_class, _destroy)                        \
+NS_IMETHODIMP_(MozExternalRefCountType) _class::Release(void)                 \
+{                                                                             \
+  MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                            \
+  if (!mRefCnt.isThreadSafe)                                                  \
+    NS_ASSERT_OWNINGTHREAD(_class);                                           \
+  nsrefcnt count = --mRefCnt;                                                 \
+  NS_LOG_RELEASE(this, count, #_class);                                       \
+  if (count == 0) {                                                           \
+    mRefCnt = 1; /* stabilize */                                              \
+    _destroy;                                                                 \
+    return 0;                                                                 \
+  }                                                                           \
+  return count;                                                               \
+}
+
+/**
+ * Use this macro to implement the Release method for a given <i>_class</i>
+ * @param _class The name of the class implementing the method
+ *
+ * A note on the 'stabilization' of the refcnt to one. At that point,
+ * the object's refcount will have gone to zero. The object's
+ * destructor may trigger code that attempts to QueryInterface() and
+ * Release() 'this' again. Doing so will temporarily increment and
+ * decrement the refcount. (Only a logic error would make one try to
+ * keep a permanent hold on 'this'.)  To prevent re-entering the
+ * destructor, we make sure that no balanced refcounting can return
+ * the refcount to |0|.
+ */
+#define NS_IMPL_RELEASE(_class) \
+  NS_IMPL_RELEASE_WITH_DESTROY(_class, delete (this))
+
+/**
+ * Use this macro to implement the Release method for a given <i>_class</i>
+ * implemented as a wholly owned aggregated object intended to implement
+ * interface(s) for its owner
+ * @param _class The name of the class implementing the method
+ * @param _aggregator the owning/containing object
+ */
+#define NS_IMPL_RELEASE_USING_AGGREGATOR(_class, _aggregator)                 \
+NS_IMETHODIMP_(MozExternalRefCountType) _class::Release(void)                 \
+{                                                                             \
+  NS_PRECONDITION(_aggregator, "null aggregator");                            \
+  return (_aggregator)->Release();                                            \
+}
+
+
+#define NS_IMPL_CYCLE_COLLECTING_ADDREF(_class)                               \
+NS_IMETHODIMP_(MozExternalRefCountType) _class::AddRef(void)                  \
+{                                                                             \
+  MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                                  \
+  MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");                        \
+  NS_ASSERT_OWNINGTHREAD(_class);                                             \
+  nsISupports *base = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this);    \
+  nsrefcnt count = mRefCnt.incr(base);                                        \
+  NS_LOG_ADDREF(this, count, #_class, sizeof(*this));                         \
+  return count;                                                               \
+}
+
+#define NS_IMPL_CYCLE_COLLECTING_RELEASE_WITH_DESTROY(_class, _destroy)       \
+NS_IMETHODIMP_(MozExternalRefCountType) _class::Release(void)                 \
+{                                                                             \
+  MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                            \
+  NS_ASSERT_OWNINGTHREAD(_class);                                             \
+  nsISupports *base = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this);    \
+  nsrefcnt count = mRefCnt.decr(base);                                        \
+  NS_LOG_RELEASE(this, count, #_class);                                       \
+  return count;                                                               \
+}                                                                             \
+NS_IMETHODIMP_(void) _class::DeleteCycleCollectable(void)                     \
+{                                                                             \
+  _destroy;                                                                   \
+}
+
+#define NS_IMPL_CYCLE_COLLECTING_RELEASE(_class)                              \
+  NS_IMPL_CYCLE_COLLECTING_RELEASE_WITH_DESTROY(_class, delete (this))
+
+// _LAST_RELEASE can be useful when certain resources should be released
+// as soon as we know the object will be deleted.
+#define NS_IMPL_CYCLE_COLLECTING_RELEASE_WITH_LAST_RELEASE(_class, _last)     \
+NS_IMETHODIMP_(MozExternalRefCountType) _class::Release(void)                 \
+{                                                                             \
+  MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");                            \
+  NS_ASSERT_OWNINGTHREAD(_class);                                             \
+  bool shouldDelete = false;                                                  \
+  nsISupports *base = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this);    \
+  nsrefcnt count = mRefCnt.decr(base, &shouldDelete);                         \
+  NS_LOG_RELEASE(this, count, #_class);                                       \
+  if (count == 0) {                                                           \
+      mRefCnt.incr(base);                                                     \
+      _last;                                                                  \
+      mRefCnt.decr(base);                                                     \
+      if (shouldDelete) {                                                     \
+          mRefCnt.stabilizeForDeletion();                                     \
+          DeleteCycleCollectable();                                           \
+      }                                                                       \
+  }                                                                           \
+  return count;                                                               \
+}                                                                             \
+NS_IMETHODIMP_(void) _class::DeleteCycleCollectable(void)                     \
+{                                                                             \
+  delete this;                                                                \
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+/**
+ * There are two ways of implementing QueryInterface, and we use both:
+ *
+ * Table-driven QueryInterface uses a static table of IID->offset mappings
+ * and a shared helper function. Using it tends to reduce codesize and improve
+ * runtime performance (due to processor cache hits).
+ *
+ * Macro-driven QueryInterface generates a QueryInterface function directly
+ * using common macros. This is necessary if special QueryInterface features
+ * are being used (such as tearoffs and conditional interfaces).
+ *
+ * These methods can be combined into a table-driven function call followed
+ * by custom code for tearoffs and conditionals.
+ */
+
+struct QITableEntry
+{
+  const nsIID* iid;     // null indicates end of the QITableEntry array
+  int32_t   offset;
+};
+
+nsresult NS_FASTCALL
+NS_TableDrivenQI(void* aThis, REFNSIID aIID,
+                 void** aInstancePtr, const QITableEntry* aEntries);
+
+/**
+ * Implement table-driven queryinterface
+ */
+
+#define NS_INTERFACE_TABLE_HEAD(_class)                                       \
+NS_IMETHODIMP _class::QueryInterface(REFNSIID aIID, void** aInstancePtr)      \
+{                                                                             \
+  NS_ASSERTION(aInstancePtr,                                                  \
+               "QueryInterface requires a non-NULL destination!");            \
+  nsresult rv = NS_ERROR_FAILURE;
+
+#define NS_INTERFACE_TABLE_BEGIN                                              \
+  static const QITableEntry table[] = {
+
+#define NS_INTERFACE_TABLE_ENTRY(_class, _interface)                          \
+  { &NS_GET_IID(_interface),                                                  \
+    int32_t(reinterpret_cast<char*>(                                          \
+                        static_cast<_interface*>((_class*) 0x1000)) -         \
+               reinterpret_cast<char*>((_class*) 0x1000))                     \
+  },
+
+#define NS_INTERFACE_TABLE_ENTRY_AMBIGUOUS(_class, _interface, _implClass)    \
+  { &NS_GET_IID(_interface),                                                  \
+    int32_t(reinterpret_cast<char*>(                                          \
+                        static_cast<_interface*>(                             \
+                                       static_cast<_implClass*>(              \
+                                                      (_class*) 0x1000))) -   \
+               reinterpret_cast<char*>((_class*) 0x1000))                     \
+  },
+
+/*
+ * XXX: we want to use mozilla::ArrayLength (or equivalent,
+ * MOZ_ARRAY_LENGTH) in this condition, but some versions of GCC don't
+ * see that the static_assert condition is actually constant in those
+ * cases, even with constexpr support (?).
+ */
+#define NS_INTERFACE_TABLE_END_WITH_PTR(_ptr)                                 \
+  { nullptr, 0 } };                                                           \
+  static_assert((sizeof(table)/sizeof(table[0])) > 1, "need at least 1 interface"); \
+  rv = NS_TableDrivenQI(static_cast<void*>(_ptr),                             \
+                        aIID, aInstancePtr, table);
+
+#define NS_INTERFACE_TABLE_END                                                \
+  NS_INTERFACE_TABLE_END_WITH_PTR(this)
+
+#define NS_INTERFACE_TABLE_TAIL                                               \
+  return rv;                                                                  \
+}
+
+#define NS_INTERFACE_TABLE_TAIL_INHERITING(_baseclass)                        \
+  if (NS_SUCCEEDED(rv))                                                       \
+    return rv;                                                                \
+  return _baseclass::QueryInterface(aIID, aInstancePtr);                      \
+}
+
+#define NS_INTERFACE_TABLE_TAIL_USING_AGGREGATOR(_aggregator)                 \
+  if (NS_SUCCEEDED(rv))                                                       \
+    return rv;                                                                \
+  NS_ASSERTION(_aggregator, "null aggregator");                               \
+  return _aggregator->QueryInterface(aIID, aInstancePtr)                      \
+}
+
+/**
+ * This implements query interface with two assumptions: First, the
+ * class in question implements nsISupports and its own interface and
+ * nothing else. Second, the implementation of the class's primary
+ * inheritance chain leads to its own interface.
+ *
+ * @param _class The name of the class implementing the method
+ * @param _classiiddef The name of the #define symbol that defines the IID
+ * for the class (e.g. NS_ISUPPORTS_IID)
+ */
+
+#define NS_IMPL_QUERY_HEAD(_class)                                            \
+NS_IMETHODIMP _class::QueryInterface(REFNSIID aIID, void** aInstancePtr)      \
+{                                                                             \
+  NS_ASSERTION(aInstancePtr,                                                  \
+               "QueryInterface requires a non-NULL destination!");            \
+  nsISupports* foundInterface;
+
+#define NS_IMPL_QUERY_BODY(_interface)                                        \
+  if ( aIID.Equals(NS_GET_IID(_interface)) )                                  \
+    foundInterface = static_cast<_interface*>(this);                          \
+  else
+
+#define NS_IMPL_QUERY_BODY_CONDITIONAL(_interface, condition)                 \
+  if ( (condition) && aIID.Equals(NS_GET_IID(_interface)))                    \
+    foundInterface = static_cast<_interface*>(this);                          \
+  else
+
+#define NS_IMPL_QUERY_BODY_AMBIGUOUS(_interface, _implClass)                  \
+  if ( aIID.Equals(NS_GET_IID(_interface)) )                                  \
+    foundInterface = static_cast<_interface*>(                                \
+                                    static_cast<_implClass*>(this));          \
+  else
+
+#define NS_IMPL_QUERY_BODY_AGGREGATED(_interface, _aggregate)                 \
+  if ( aIID.Equals(NS_GET_IID(_interface)) )                                  \
+    foundInterface = static_cast<_interface*>(_aggregate);                    \
+  else
+
+#define NS_IMPL_QUERY_TAIL_GUTS                                               \
+    foundInterface = 0;                                                       \
+  nsresult status;                                                            \
+  if ( !foundInterface )                                                      \
+    {                                                                         \
+      /* nsISupports should be handled by this point. If not, fail. */        \
+      MOZ_ASSERT(!aIID.Equals(NS_GET_IID(nsISupports)));                      \
+      status = NS_NOINTERFACE;                                                \
+    }                                                                         \
+  else                                                                        \
+    {                                                                         \
+      NS_ADDREF(foundInterface);                                              \
+      status = NS_OK;                                                         \
+    }                                                                         \
+  *aInstancePtr = foundInterface;                                             \
+  return status;                                                              \
+}
+
+#define NS_IMPL_QUERY_TAIL_INHERITING(_baseclass)                             \
+    foundInterface = 0;                                                       \
+  nsresult status;                                                            \
+  if ( !foundInterface )                                                      \
+    status = _baseclass::QueryInterface(aIID, (void**)&foundInterface);       \
+  else                                                                        \
+    {                                                                         \
+      NS_ADDREF(foundInterface);                                              \
+      status = NS_OK;                                                         \
+    }                                                                         \
+  *aInstancePtr = foundInterface;                                             \
+  return status;                                                              \
+}
+
+#define NS_IMPL_QUERY_TAIL_USING_AGGREGATOR(_aggregator)                      \
+    foundInterface = 0;                                                       \
+  nsresult status;                                                            \
+  if ( !foundInterface ) {                                                    \
+    NS_ASSERTION(_aggregator, "null aggregator");                             \
+    status = _aggregator->QueryInterface(aIID, (void**)&foundInterface);      \
+  } else                                                                      \
+    {                                                                         \
+      NS_ADDREF(foundInterface);                                              \
+      status = NS_OK;                                                         \
+    }                                                                         \
+  *aInstancePtr = foundInterface;                                             \
+  return status;                                                              \
+}
+
+#define NS_IMPL_QUERY_TAIL(_supports_interface)                               \
+  NS_IMPL_QUERY_BODY_AMBIGUOUS(nsISupports, _supports_interface)              \
+  NS_IMPL_QUERY_TAIL_GUTS
+
+
+/*
+  This is the new scheme.  Using this notation now will allow us to switch to
+  a table driven mechanism when it's ready.  Note the difference between this
+  and the (currently) underlying NS_IMPL_QUERY_INTERFACE mechanism.  You must
+  explicitly mention |nsISupports| when using the interface maps.
+*/
+#define NS_INTERFACE_MAP_BEGIN(_implClass)      NS_IMPL_QUERY_HEAD(_implClass)
+#define NS_INTERFACE_MAP_ENTRY(_interface)      NS_IMPL_QUERY_BODY(_interface)
+#define NS_INTERFACE_MAP_ENTRY_CONDITIONAL(_interface, condition)             \
+  NS_IMPL_QUERY_BODY_CONDITIONAL(_interface, condition)
+#define NS_INTERFACE_MAP_ENTRY_AGGREGATED(_interface,_aggregate)              \
+  NS_IMPL_QUERY_BODY_AGGREGATED(_interface,_aggregate)
+
+#define NS_INTERFACE_MAP_END                    NS_IMPL_QUERY_TAIL_GUTS
+#define NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(_interface, _implClass)              \
+  NS_IMPL_QUERY_BODY_AMBIGUOUS(_interface, _implClass)
+#define NS_INTERFACE_MAP_END_INHERITING(_baseClass)                           \
+  NS_IMPL_QUERY_TAIL_INHERITING(_baseClass)
+#define NS_INTERFACE_MAP_END_AGGREGATED(_aggregator)                          \
+  NS_IMPL_QUERY_TAIL_USING_AGGREGATOR(_aggregator)
+
+#define NS_INTERFACE_TABLE0(_class)                                           \
+  NS_INTERFACE_TABLE_BEGIN                                                    \
+    NS_INTERFACE_TABLE_ENTRY(_class, nsISupports)                             \
+  NS_INTERFACE_TABLE_END
+
+#define NS_INTERFACE_TABLE(aClass, ...)                                       \
+  MOZ_STATIC_ASSERT_VALID_ARG_COUNT(__VA_ARGS__);                             \
+  NS_INTERFACE_TABLE_BEGIN                                                    \
+    MOZ_FOR_EACH(NS_INTERFACE_TABLE_ENTRY, (aClass,), (__VA_ARGS__))          \
+    NS_INTERFACE_TABLE_ENTRY_AMBIGUOUS(aClass, nsISupports,                   \
+                                       MOZ_ARG_1(__VA_ARGS__))                \
+  NS_INTERFACE_TABLE_END
+
+#define NS_IMPL_QUERY_INTERFACE0(_class)                                      \
+  NS_INTERFACE_TABLE_HEAD(_class)                                             \
+  NS_INTERFACE_TABLE0(_class)                                                 \
+  NS_INTERFACE_TABLE_TAIL
+
+#define NS_IMPL_QUERY_INTERFACE(aClass, ...)                                  \
+  NS_INTERFACE_TABLE_HEAD(aClass)                                             \
+  NS_INTERFACE_TABLE(aClass, __VA_ARGS__)                                     \
+  NS_INTERFACE_TABLE_TAIL
+
+/**
+ * Declare that you're going to inherit from something that already
+ * implements nsISupports, but also implements an additional interface, thus
+ * causing an ambiguity. In this case you don't need another mRefCnt, you
+ * just need to forward the definitions to the appropriate superclass. E.g.
+ *
+ * class Bar : public Foo, public nsIBar {  // both provide nsISupports
+ * public:
+ *   NS_DECL_ISUPPORTS_INHERITED
+ *   ...other nsIBar and Bar methods...
+ * };
+ */
+#define NS_DECL_ISUPPORTS_INHERITED                                           \
+public:                                                                       \
+  NS_IMETHOD QueryInterface(REFNSIID aIID,                                    \
+                            void** aInstancePtr) override;                \
+  NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override;             \
+  NS_IMETHOD_(MozExternalRefCountType) Release(void) override;            \
+
+/**
+ * These macros can be used in conjunction with NS_DECL_ISUPPORTS_INHERITED
+ * to implement the nsISupports methods, forwarding the invocations to a
+ * superclass that already implements nsISupports.
+ *
+ * Note that I didn't make these inlined because they're virtual methods.
+ */
+
+#define NS_IMPL_ADDREF_INHERITED(Class, Super)                                \
+NS_IMETHODIMP_(MozExternalRefCountType) Class::AddRef(void)                   \
+{                                                                             \
+  MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(Class)                                   \
+  nsrefcnt r = Super::AddRef();                                               \
+  NS_LOG_ADDREF(this, r, #Class, sizeof(*this));                              \
+  return r;                                                                   \
+}
+
+#define NS_IMPL_RELEASE_INHERITED(Class, Super)                               \
+NS_IMETHODIMP_(MozExternalRefCountType) Class::Release(void)                  \
+{                                                                             \
+  nsrefcnt r = Super::Release();                                              \
+  NS_LOG_RELEASE(this, r, #Class);                                            \
+  return r;                                                                   \
+}
+
+/**
+ * As above but not logging the addref/release; needed if the base
+ * class might be aggregated.
+ */
+#define NS_IMPL_NONLOGGING_ADDREF_INHERITED(Class, Super)                     \
+NS_IMETHODIMP_(MozExternalRefCountType) Class::AddRef(void)                   \
+{                                                                             \
+  MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(Class)                                   \
+  return Super::AddRef();                                                     \
+}
+
+#define NS_IMPL_NONLOGGING_RELEASE_INHERITED(Class, Super)                    \
+NS_IMETHODIMP_(MozExternalRefCountType) Class::Release(void)                  \
+{                                                                             \
+  return Super::Release();                                                    \
+}
+
+#define NS_INTERFACE_TABLE_INHERITED0(Class) /* Nothing to do here */
+
+#define NS_INTERFACE_TABLE_INHERITED(aClass, ...)                             \
+  MOZ_STATIC_ASSERT_VALID_ARG_COUNT(__VA_ARGS__);                             \
+  NS_INTERFACE_TABLE_BEGIN                                                    \
+    MOZ_FOR_EACH(NS_INTERFACE_TABLE_ENTRY, (aClass,), (__VA_ARGS__))          \
+  NS_INTERFACE_TABLE_END
+
+#define NS_IMPL_QUERY_INTERFACE_INHERITED(aClass, aSuper, ...)                \
+  NS_INTERFACE_TABLE_HEAD(aClass)                                             \
+  NS_INTERFACE_TABLE_INHERITED(aClass, __VA_ARGS__)                           \
+  NS_INTERFACE_TABLE_TAIL_INHERITING(aSuper)
+
+/**
+ * Convenience macros for implementing all nsISupports methods for
+ * a simple class.
+ * @param _class The name of the class implementing the method
+ * @param _classiiddef The name of the #define symbol that defines the IID
+ * for the class (e.g. NS_ISUPPORTS_IID)
+ */
+
+#define NS_IMPL_ISUPPORTS0(_class)                                            \
+  NS_IMPL_ADDREF(_class)                                                      \
+  NS_IMPL_RELEASE(_class)                                                     \
+  NS_IMPL_QUERY_INTERFACE0(_class)
+
+#define NS_IMPL_ISUPPORTS(aClass, ...)                                        \
+  NS_IMPL_ADDREF(aClass)                                                      \
+  NS_IMPL_RELEASE(aClass)                                                     \
+  NS_IMPL_QUERY_INTERFACE(aClass, __VA_ARGS__)
+
+#define NS_IMPL_ISUPPORTS_INHERITED0(aClass, aSuper)                          \
+    NS_INTERFACE_TABLE_HEAD(aClass)                                           \
+    NS_INTERFACE_TABLE_TAIL_INHERITING(aSuper)                                \
+    NS_IMPL_ADDREF_INHERITED(aClass, aSuper)                                  \
+    NS_IMPL_RELEASE_INHERITED(aClass, aSuper)                                 \
+
+#define NS_IMPL_ISUPPORTS_INHERITED(aClass, aSuper, ...)                      \
+  NS_IMPL_QUERY_INTERFACE_INHERITED(aClass, aSuper, __VA_ARGS__)              \
+  NS_IMPL_ADDREF_INHERITED(aClass, aSuper)                                    \
+  NS_IMPL_RELEASE_INHERITED(aClass, aSuper)
+
+/*
+ * Macro to glue together a QI that starts with an interface table
+ * and segues into an interface map (e.g. it uses singleton classinfo
+ * or tearoffs).
+ */
+#define NS_INTERFACE_TABLE_TO_MAP_SEGUE \
+  if (rv == NS_OK) return rv; \
+  nsISupports* foundInterface;
+
+
+///////////////////////////////////////////////////////////////////////////////
+/**
+ *
+ * Threadsafe implementations of the ISupports convenience macros.
+ *
+ * @note  These are not available when linking against the standalone glue,
+ *        because the implementation requires PR_ symbols.
+ */
+#define NS_INTERFACE_MAP_END_THREADSAFE NS_IMPL_QUERY_TAIL_GUTS
+
+/**
+ * Macro to generate nsIClassInfo methods for classes which do not have
+ * corresponding nsIFactory implementations.
+ */
+#define NS_IMPL_THREADSAFE_CI(_class)                                         \
+NS_IMETHODIMP                                                                 \
+_class::GetInterfaces(uint32_t* _count, nsIID*** _array)                      \
+{                                                                             \
+  return NS_CI_INTERFACE_GETTER_NAME(_class)(_count, _array);                 \
+}                                                                             \
+                                                                              \
+NS_IMETHODIMP                                                                 \
+_class::GetScriptableHelper(nsIXPCScriptable** _retval)                       \
+{                                                                             \
+  *_retval = nullptr;                                                         \
+  return NS_OK;                                                               \
+}                                                                             \
+                                                                              \
+NS_IMETHODIMP                                                                 \
+_class::GetContractID(char** _contractID)                                     \
+{                                                                             \
+  *_contractID = nullptr;                                                     \
+  return NS_OK;                                                               \
+}                                                                             \
+                                                                              \
+NS_IMETHODIMP                                                                 \
+_class::GetClassDescription(char** _classDescription)                         \
+{                                                                             \
+  *_classDescription = nullptr;                                               \
+  return NS_OK;                                                               \
+}                                                                             \
+                                                                              \
+NS_IMETHODIMP                                                                 \
+_class::GetClassID(nsCID** _classID)                                          \
+{                                                                             \
+  *_classID = nullptr;                                                        \
+  return NS_OK;                                                               \
+}                                                                             \
+                                                                              \
+NS_IMETHODIMP                                                                 \
+_class::GetFlags(uint32_t* _flags)                                            \
+{                                                                             \
+  *_flags = nsIClassInfo::THREADSAFE;                                         \
+  return NS_OK;                                                               \
+}                                                                             \
+                                                                              \
+NS_IMETHODIMP                                                                 \
+_class::GetClassIDNoAlloc(nsCID* _classIDNoAlloc)                             \
+{                                                                             \
+  return NS_ERROR_NOT_AVAILABLE;                                              \
+}
+
+#endif
diff --git a/xpcom/glue/nsISupportsUtils.h b/xpcom/glue/nsISupportsUtils.h
new file mode 100644
index 000000000..4d306d3d1
--- /dev/null
+++ b/xpcom/glue/nsISupportsUtils.h
@@ -0,0 +1,145 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsISupportsUtils_h__
+#define nsISupportsUtils_h__
+
+#include "nscore.h"
+#include "nsISupportsBase.h"
+#include "nsError.h"
+#include "nsDebug.h"
+#include "nsISupportsImpl.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/TypeTraits.h"
+
+/**
+ * Macro for adding a reference to an interface.
+ * @param _ptr The interface pointer.
+ */
+#define NS_ADDREF(_ptr) \
+  (_ptr)->AddRef()
+
+/**
+ * Macro for adding a reference to this. This macro should be used
+ * because NS_ADDREF (when tracing) may require an ambiguous cast
+ * from the pointers primary type to nsISupports. This macro sidesteps
+ * that entire problem.
+ */
+#define NS_ADDREF_THIS() \
+  AddRef()
+
+
+// Making this a |inline| |template| allows |aExpr| to be evaluated only once,
+// yet still denies you the ability to |AddRef()| an |nsCOMPtr|.
+template<class T>
+inline void
+ns_if_addref(T aExpr)
+{
+  if (aExpr) {
+    aExpr->AddRef();
+  }
+}
+
+/**
+ * Macro for adding a reference to an interface that checks for nullptr.
+ * @param _expr The interface pointer.
+ */
+#define NS_IF_ADDREF(_expr) ns_if_addref(_expr)
+
+/*
+ * Given these declarations, it explicitly OK and efficient to end a `getter' with:
+ *
+ *    NS_IF_ADDREF(*result = mThing);
+ *
+ * even if |mThing| is an |nsCOMPtr|.  If |mThing| is an |nsCOMPtr|, however, it is still
+ * _illegal_ to say |NS_IF_ADDREF(mThing)|.
+ */
+
+/**
+ * Macro for releasing a reference to an interface.
+ * @param _ptr The interface pointer.
+ */
+#define NS_RELEASE(_ptr)                                                      \
+  do {                                                                        \
+    (_ptr)->Release();                                                        \
+    (_ptr) = 0;                                                               \
+  } while (0)
+
+/**
+ * Macro for releasing a reference to this interface.
+ */
+#define NS_RELEASE_THIS() \
+    Release()
+
+/**
+ * Macro for releasing a reference to an interface, except that this
+ * macro preserves the return value from the underlying Release call.
+ * The interface pointer argument will only be NULLed if the reference count
+ * goes to zero.
+ *
+ * @param _ptr The interface pointer.
+ * @param _rc  The reference count.
+ */
+#define NS_RELEASE2(_ptr, _rc)                                                \
+  do {                                                                        \
+    _rc = (_ptr)->Release();                                                  \
+    if (0 == (_rc)) (_ptr) = 0;                                               \
+  } while (0)
+
+/**
+ * Macro for releasing a reference to an interface that checks for nullptr;
+ * @param _ptr The interface pointer.
+ */
+#define NS_IF_RELEASE(_ptr)                                                   \
+  do {                                                                        \
+    if (_ptr) {                                                               \
+      (_ptr)->Release();                                                      \
+      (_ptr) = 0;                                                             \
+    }                                                                         \
+  } while (0)
+
+/*
+ * Often you have to cast an implementation pointer, e.g., |this|, to an
+ * |nsISupports*|, but because you have multiple inheritance, a simple cast
+ * is ambiguous.  One could simply say, e.g., (given a base |nsIBase|),
+ * |static_cast<nsIBase*>(this)|; but that disguises the fact that what
+ * you are really doing is disambiguating the |nsISupports|.  You could make
+ * that more obvious with a double cast, e.g., |static_cast<nsISupports*>
+                                                           (* static_cast<nsIBase*>(this))|, but that is bulky and harder to read...
+ *
+ * The following macro is clean, short, and obvious.  In the example above,
+ * you would use it like this: |NS_ISUPPORTS_CAST(nsIBase*, this)|.
+ */
+
+#define NS_ISUPPORTS_CAST(__unambiguousBase, __expr) \
+  static_cast<nsISupports*>(static_cast<__unambiguousBase>(__expr))
+
+// a type-safe shortcut for calling the |QueryInterface()| member function
+template<class T, class DestinationType>
+inline nsresult
+CallQueryInterface(T* aSource, DestinationType** aDestination)
+{
+  // We permit nsISupports-to-nsISupports here so that one can still obtain
+  // the canonical nsISupports pointer with CallQueryInterface.
+  static_assert(!mozilla::IsSame<T, DestinationType>::value ||
+                mozilla::IsSame<DestinationType, nsISupports>::value,
+                "don't use CallQueryInterface for compile-time-determinable casts");
+
+  NS_PRECONDITION(aSource, "null parameter");
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return aSource->QueryInterface(NS_GET_TEMPLATE_IID(DestinationType),
+                                 reinterpret_cast<void**>(aDestination));
+}
+
+template <class SourceType, class DestinationType>
+inline nsresult
+CallQueryInterface(RefPtr<SourceType>& aSourcePtr, DestinationType** aDestPtr)
+{
+  return CallQueryInterface(aSourcePtr.get(), aDestPtr);
+}
+
+#endif /* __nsISupportsUtils_h */
diff --git a/xpcom/glue/nsIWeakReferenceUtils.h b/xpcom/glue/nsIWeakReferenceUtils.h
new file mode 100644
index 000000000..1c84e00df
--- /dev/null
+++ b/xpcom/glue/nsIWeakReferenceUtils.h
@@ -0,0 +1,102 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsIWeakReferenceUtils_h__
+#define nsIWeakReferenceUtils_h__
+
+#include "nsCOMPtr.h"
+#include "nsIWeakReference.h"
+
+typedef nsCOMPtr<nsIWeakReference> nsWeakPtr;
+
+/**
+ *
+ */
+
+// a type-safe shortcut for calling the |QueryReferent()| member function
+// T must inherit from nsIWeakReference, but the cast may be ambiguous.
+template<class T, class DestinationType>
+inline nsresult
+CallQueryReferent(T* aSource, DestinationType** aDestination)
+{
+  NS_PRECONDITION(aSource, "null parameter");
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return aSource->QueryReferent(NS_GET_TEMPLATE_IID(DestinationType),
+                                reinterpret_cast<void**>(aDestination));
+}
+
+
+class MOZ_STACK_CLASS nsQueryReferent final : public nsCOMPtr_helper
+{
+public:
+  nsQueryReferent(nsIWeakReference* aWeakPtr, nsresult* aError)
+    : mWeakPtr(aWeakPtr)
+    , mErrorPtr(aError)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID& aIID, void**) const
+    override;
+
+private:
+  nsIWeakReference* MOZ_NON_OWNING_REF mWeakPtr;
+  nsresult*          mErrorPtr;
+};
+
+inline const nsQueryReferent
+do_QueryReferent(nsIWeakReference* aRawPtr, nsresult* aError = 0)
+{
+  return nsQueryReferent(aRawPtr, aError);
+}
+
+
+/**
+ * Deprecated, use |do_GetWeakReference| instead.
+ */
+extern nsIWeakReference* NS_GetWeakReference(nsISupports*,
+                                             nsresult* aResult = 0);
+
+/**
+ * |do_GetWeakReference| is a convenience function that bundles up all the work needed
+ * to get a weak reference to an arbitrary object, i.e., the |QueryInterface|, test, and
+ * call through to |GetWeakReference|, and put it into your |nsCOMPtr|.
+ * It is specifically designed to cooperate with |nsCOMPtr| (or |nsWeakPtr|) like so:
+ * |nsWeakPtr myWeakPtr = do_GetWeakReference(aPtr);|.
+ */
+inline already_AddRefed<nsIWeakReference>
+do_GetWeakReference(nsISupports* aRawPtr, nsresult* aError = 0)
+{
+  return dont_AddRef(NS_GetWeakReference(aRawPtr, aError));
+}
+
+inline void
+do_GetWeakReference(nsIWeakReference* aRawPtr, nsresult* aError = 0)
+{
+  // This signature exists solely to _stop_ you from doing a bad thing.
+  //  Saying |do_GetWeakReference()| on a weak reference itself,
+  //  is very likely to be a programmer error.
+}
+
+template<class T>
+inline void
+do_GetWeakReference(already_AddRefed<T>&)
+{
+  // This signature exists solely to _stop_ you from doing the bad thing.
+  //  Saying |do_GetWeakReference()| on a pointer that is not otherwise owned by
+  //  someone else is an automatic leak.  See <http://bugzilla.mozilla.org/show_bug.cgi?id=8221>.
+}
+
+template<class T>
+inline void
+do_GetWeakReference(already_AddRefed<T>&, nsresult*)
+{
+  // This signature exists solely to _stop_ you from doing the bad thing.
+  //  Saying |do_GetWeakReference()| on a pointer that is not otherwise owned by
+  //  someone else is an automatic leak.  See <http://bugzilla.mozilla.org/show_bug.cgi?id=8221>.
+}
+
+#endif
diff --git a/xpcom/glue/nsInterfaceHashtable.h b/xpcom/glue/nsInterfaceHashtable.h
new file mode 100644
index 000000000..14368af63
--- /dev/null
+++ b/xpcom/glue/nsInterfaceHashtable.h
@@ -0,0 +1,142 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsInterfaceHashtable_h__
+#define nsInterfaceHashtable_h__
+
+#include "nsBaseHashtable.h"
+#include "nsHashKeys.h"
+#include "nsCOMPtr.h"
+
+/**
+ * templated hashtable class maps keys to interface pointers.
+ * See nsBaseHashtable for complete declaration.
+ * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
+ *   for a complete specification.
+ * @param Interface the interface-type being wrapped
+ * @see nsDataHashtable, nsClassHashtable
+ */
+template<class KeyClass, class Interface>
+class nsInterfaceHashtable
+  : public nsBaseHashtable<KeyClass, nsCOMPtr<Interface>, Interface*>
+{
+public:
+  typedef typename KeyClass::KeyType KeyType;
+  typedef Interface* UserDataType;
+  typedef nsBaseHashtable<KeyClass, nsCOMPtr<Interface>, Interface*> base_type;
+
+  nsInterfaceHashtable() {}
+  explicit nsInterfaceHashtable(uint32_t aInitLength)
+    : nsBaseHashtable<KeyClass, nsCOMPtr<Interface>, Interface*>(aInitLength)
+  {
+  }
+
+  /**
+   * @copydoc nsBaseHashtable::Get
+   * @param aData This is an XPCOM getter, so aData is already_addrefed.
+   *   If the key doesn't exist, aData will be set to nullptr.
+   */
+  bool Get(KeyType aKey, UserDataType* aData) const;
+
+  /**
+   * @copydoc nsBaseHashtable::Get
+   */
+  already_AddRefed<Interface> Get(KeyType aKey) const;
+
+  /**
+   * Gets a weak reference to the hashtable entry.
+   * @param aFound If not nullptr, will be set to true if the entry is found,
+   *               to false otherwise.
+   * @return The entry, or nullptr if not found. Do not release this pointer!
+   */
+  Interface* GetWeak(KeyType aKey, bool* aFound = nullptr) const;
+};
+
+template<typename K, typename T>
+inline void
+ImplCycleCollectionUnlink(nsInterfaceHashtable<K, T>& aField)
+{
+  aField.Clear();
+}
+
+template<typename K, typename T>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            const nsInterfaceHashtable<K, T>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  for (auto iter = aField.ConstIter(); !iter.Done(); iter.Next()) {
+    CycleCollectionNoteChild(aCallback, iter.UserData(), aName, aFlags);
+  }
+}
+
+//
+// nsInterfaceHashtable definitions
+//
+
+template<class KeyClass, class Interface>
+bool
+nsInterfaceHashtable<KeyClass, Interface>::Get(KeyType aKey,
+                                               UserDataType* aInterface) const
+{
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+
+  if (ent) {
+    if (aInterface) {
+      *aInterface = ent->mData;
+
+      NS_IF_ADDREF(*aInterface);
+    }
+
+    return true;
+  }
+
+  // if the key doesn't exist, set *aInterface to null
+  // so that it is a valid XPCOM getter
+  if (aInterface) {
+    *aInterface = nullptr;
+  }
+
+  return false;
+}
+
+template<class KeyClass, class Interface>
+already_AddRefed<Interface>
+nsInterfaceHashtable<KeyClass, Interface>::Get(KeyType aKey) const
+{
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+  if (!ent) {
+    return nullptr;
+  }
+
+  nsCOMPtr<Interface> copy = ent->mData;
+  return copy.forget();
+}
+
+template<class KeyClass, class Interface>
+Interface*
+nsInterfaceHashtable<KeyClass, Interface>::GetWeak(KeyType aKey,
+                                                   bool* aFound) const
+{
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+
+  if (ent) {
+    if (aFound) {
+      *aFound = true;
+    }
+
+    return ent->mData;
+  }
+
+  // Key does not exist, return nullptr and set aFound to false
+  if (aFound) {
+    *aFound = false;
+  }
+  return nullptr;
+}
+
+#endif // nsInterfaceHashtable_h__
diff --git a/xpcom/glue/nsJSThingHashtable.h b/xpcom/glue/nsJSThingHashtable.h
new file mode 100644
index 000000000..8c1b1447d
--- /dev/null
+++ b/xpcom/glue/nsJSThingHashtable.h
@@ -0,0 +1,61 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsJSThingHashtable_h__
+#define nsJSThingHashtable_h__
+
+#include "nsHashKeys.h"
+#include "nsBaseHashtable.h"
+
+namespace JS {
+template<class T>
+class Heap;
+} /* namespace JS */
+
+/**
+ * A wrapper for hash keys that sets ALLOW_MEMMOVE to false.
+ *
+ * This is used in the implementation of nsJSThingHashtable and is not intended
+ * to be used directly.
+ *
+ * It is necessary for hash tables containing JS::Heap<T> values as these must
+ * be copied rather than memmoved.
+ */
+template<class T>
+class nsHashKeyDisallowMemmove : public T
+{
+public:
+  explicit nsHashKeyDisallowMemmove(const typename T::KeyTypePointer aKey) : T(aKey) {}
+  enum { ALLOW_MEMMOVE = false };
+};
+
+
+/**
+ * Templated hashtable class for use on the heap where the values are JS GC things.
+ *
+ * Storing JS GC thing pointers on the heap requires wrapping them in a
+ * JS::Heap<T>, and this class takes care of that while presenting an interface
+ * in terms of the wrapped type T.
+ *
+ * For example, to store a hashtable mapping strings to JSObject pointers, you
+ * can declare a data member like this:
+ *
+ *   nsJSThingHashtable<nsStringHashKey, JSObject*> mStringToObjectMap;
+ *
+ * See nsBaseHashtable for complete declaration
+ * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
+ *   for a complete specification.
+ * @param DataType the datatype being wrapped, must be a JS GC thing.
+ * @see nsInterfaceHashtable, nsClassHashtable
+ */
+template<class KeyClass, class DataType>
+class nsJSThingHashtable
+  : public nsBaseHashtable<nsHashKeyDisallowMemmove<KeyClass>,
+                           JS::Heap<DataType>, DataType>
+{
+};
+
+#endif // nsJSThingHashtable_h__
diff --git a/xpcom/glue/nsMemory.cpp b/xpcom/glue/nsMemory.cpp
new file mode 100644
index 000000000..3bf7c1f0f
--- /dev/null
+++ b/xpcom/glue/nsMemory.cpp
@@ -0,0 +1,53 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsXPCOM.h"
+#include "nsMemory.h"
+#include "nsIMemory.h"
+#include "nsXPCOMPrivate.h"
+#include "nsDebug.h"
+#include "nsISupportsUtils.h"
+#include "nsCOMPtr.h"
+
+////////////////////////////////////////////////////////////////////////////////
+// nsMemory static helper routines
+
+nsresult
+nsMemory::HeapMinimize(bool aImmediate)
+{
+  nsCOMPtr<nsIMemory> mem;
+  nsresult rv = NS_GetMemoryManager(getter_AddRefs(mem));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  return mem->HeapMinimize(aImmediate);
+}
+
+void*
+nsMemory::Clone(const void* aPtr, size_t aSize)
+{
+  void* newPtr = NS_Alloc(aSize);
+  if (newPtr) {
+    memcpy(newPtr, aPtr, aSize);
+  }
+  return newPtr;
+}
+
+nsIMemory*
+nsMemory::GetGlobalMemoryService()
+{
+  nsIMemory* mem;
+  nsresult rv = NS_GetMemoryManager(&mem);
+  if (NS_FAILED(rv)) {
+    return nullptr;
+  }
+
+  return mem;
+}
+
+//----------------------------------------------------------------------
+
diff --git a/xpcom/glue/nsMemory.h b/xpcom/glue/nsMemory.h
new file mode 100644
index 000000000..6f19b8117
--- /dev/null
+++ b/xpcom/glue/nsMemory.h
@@ -0,0 +1,136 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMemory_h__
+#define nsMemory_h__
+
+#include "nsXPCOM.h"
+
+class nsIMemory;
+
+#define NS_MEMORY_CONTRACTID "@mozilla.org/xpcom/memory-service;1"
+#define NS_MEMORY_CID                                \
+{ /* 30a04e40-38e7-11d4-8cf5-0060b0fc14a3 */         \
+    0x30a04e40,                                      \
+    0x38e7,                                          \
+    0x11d4,                                          \
+    {0x8c, 0xf5, 0x00, 0x60, 0xb0, 0xfc, 0x14, 0xa3} \
+}
+
+
+/**
+ * Static helper routines to manage memory. These routines allow easy access
+ * to xpcom's built-in (global) nsIMemory implementation, without needing
+ * to go through the service manager to get it. However this requires clients
+ * to link with the xpcom DLL.
+ *
+ * This class is not threadsafe and is intented for use only on the main
+ * thread.
+ */
+class nsMemory
+{
+public:
+  static nsresult   HeapMinimize(bool aImmediate);
+  static void*      Clone(const void* aPtr, size_t aSize);
+  static nsIMemory* GetGlobalMemoryService();       // AddRefs
+};
+
+/**
+ * Macro to free all elements of an XPCOM array of a given size using
+ * freeFunc, then frees the array itself using free().
+ *
+ * Note that this macro (and its wrappers) can be used to deallocate a
+ * partially- or completely-built array while unwinding an error
+ * condition inside the XPCOM routine that was going to return the
+ * array.  For this to work on a partially-built array, your code
+ * needs to be building the array from index 0 upwards, and simply
+ * pass the number of elements that have already been built (and thus
+ * need to be freed) as |size|.
+ *
+ * Thanks to <alecf@netscape.com> for suggesting this form, which
+ * allows the macro to be used with NS_RELEASE / NS_RELEASE_IF in
+ * addition to free.
+ *
+ * @param size      Number of elements in the array.  If not a constant, this
+ *                  should be a int32_t.  Note that this means this macro
+ *                  will not work if size >= 2^31.
+ * @param array     The array to be freed.
+ * @param freeFunc  The function or macro to be used to free it.
+ *                  For arrays of nsISupports (or any class derived
+ *                  from it), NS_IF_RELEASE (or NS_RELEASE) should be
+ *                  passed as freeFunc.  For most (all?) other pointer
+ *                  types (including XPCOM strings and wstrings),
+ *                  free should be used.
+ */
+#define NS_FREE_XPCOM_POINTER_ARRAY(size, array, freeFunc)                    \
+    PR_BEGIN_MACRO                                                            \
+        int32_t iter_ = int32_t(size);                                        \
+        while (--iter_ >= 0)                                                  \
+            freeFunc((array)[iter_]);                                         \
+        NS_Free((array));                                                     \
+    PR_END_MACRO
+
+// convenience macros for commonly used calls.  mmmmm.  syntactic sugar.
+
+/**
+ * Macro to free arrays of non-refcounted objects allocated by the
+ * shared allocator (nsMemory) such as strings and wstrings.  A
+ * convenience wrapper around NS_FREE_XPCOM_POINTER_ARRAY.
+ *
+ * @param size      Number of elements in the array.  If not a constant, this
+ *                  should be a int32_t.  Note that this means this macro
+ *                  will not work if size >= 2^31.
+ * @param array     The array to be freed.
+ */
+#define NS_FREE_XPCOM_ALLOCATED_POINTER_ARRAY(size, array)                    \
+    NS_FREE_XPCOM_POINTER_ARRAY((size), (array), NS_Free)
+
+/**
+ * Macro to free an array of pointers to nsISupports (or classes
+ * derived from it).  A convenience wrapper around
+ * NS_FREE_XPCOM_POINTER_ARRAY.
+ *
+ * Note that if you know that none of your nsISupports pointers are
+ * going to be 0, you can gain a bit of speed by calling
+ * NS_FREE_XPCOM_POINTER_ARRAY directly and using NS_RELEASE as your
+ * free function.
+ *
+ * @param size      Number of elements in the array.  If not a constant, this
+ *                  should be a int32_t.  Note that this means this macro
+ *                  will not work if size >= 2^31.
+ * @param array     The array to be freed.
+ */
+#define NS_FREE_XPCOM_ISUPPORTS_POINTER_ARRAY(size, array)                    \
+    NS_FREE_XPCOM_POINTER_ARRAY((size), (array), NS_IF_RELEASE)
+
+/**
+ * A macro, NS_ALIGNMENT_OF(t_) that determines the alignment
+ * requirements of a type.
+ */
+namespace mozilla {
+template<class T>
+struct AlignmentTestStruct
+{
+  char c;
+  T t;
+};
+} // namespace mozilla
+
+#define NS_ALIGNMENT_OF(t_) \
+  (sizeof(mozilla::AlignmentTestStruct<t_>) - sizeof(t_))
+
+/**
+ * An enumeration type used to represent a method of assignment.
+ */
+enum nsAssignmentType
+{
+  NS_ASSIGNMENT_COPY,   // copy by value
+  NS_ASSIGNMENT_DEPEND, // copy by reference
+  NS_ASSIGNMENT_ADOPT   // copy by reference (take ownership of resource)
+};
+
+#endif // nsMemory_h__
+
diff --git a/xpcom/glue/nsPointerHashKeys.h b/xpcom/glue/nsPointerHashKeys.h
new file mode 100644
index 000000000..a89843101
--- /dev/null
+++ b/xpcom/glue/nsPointerHashKeys.h
@@ -0,0 +1,48 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Definitions for nsPtrHashKey<T> and nsVoidPtrHashKey.  */
+
+#ifndef nsPointerHashKeys_h
+#define nsPointerHashKeys_h
+
+#include "nscore.h"
+
+#include "mozilla/Attributes.h"
+
+/**
+ * hashkey wrapper using T* KeyType
+ *
+ * @see nsTHashtable::EntryType for specification
+ */
+template<class T>
+class nsPtrHashKey : public PLDHashEntryHdr
+{
+public:
+  typedef T* KeyType;
+  typedef const T* KeyTypePointer;
+
+  explicit nsPtrHashKey(const T* aKey) : mKey(const_cast<T*>(aKey)) {}
+  nsPtrHashKey(const nsPtrHashKey<T>& aToCopy) : mKey(aToCopy.mKey) {}
+  ~nsPtrHashKey() {}
+
+  KeyType GetKey() const { return mKey; }
+  bool KeyEquals(KeyTypePointer aKey) const { return aKey == mKey; }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey) { return aKey; }
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return NS_PTR_TO_UINT32(aKey) >> 2;
+  }
+  enum { ALLOW_MEMMOVE = true };
+
+protected:
+  T* MOZ_NON_OWNING_REF mKey;
+};
+
+typedef nsPtrHashKey<const void> nsVoidPtrHashKey;
+
+#endif // nsPointerHashKeys_h
diff --git a/xpcom/glue/nsProxyRelease.cpp b/xpcom/glue/nsProxyRelease.cpp
new file mode 100644
index 000000000..1a8150cc6
--- /dev/null
+++ b/xpcom/glue/nsProxyRelease.cpp
@@ -0,0 +1,21 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsProxyRelease.h"
+#include "nsThreadUtils.h"
+
+namespace detail {
+
+/* static */ void
+ProxyReleaseChooser<true>::ProxyReleaseISupports(nsIEventTarget* aTarget,
+                                                 nsISupports* aDoomed,
+                                                 bool aAlwaysProxy)
+{
+  ::detail::ProxyRelease<nsISupports>(aTarget, dont_AddRef(aDoomed),
+                                      aAlwaysProxy);
+}
+
+} // namespace detail
diff --git a/xpcom/glue/nsProxyRelease.h b/xpcom/glue/nsProxyRelease.h
new file mode 100644
index 000000000..d99f970b9
--- /dev/null
+++ b/xpcom/glue/nsProxyRelease.h
@@ -0,0 +1,353 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsProxyRelease_h__
+#define nsProxyRelease_h__
+
+#include "nsIEventTarget.h"
+#include "nsIThread.h"
+#include "nsCOMPtr.h"
+#include "nsAutoPtr.h"
+#include "MainThreadUtils.h"
+#include "nsThreadUtils.h"
+#include "mozilla/Likely.h"
+#include "mozilla/Move.h"
+#include "mozilla/TypeTraits.h"
+#include "mozilla/Unused.h"
+
+#ifdef XPCOM_GLUE_AVOID_NSPR
+#error NS_ProxyRelease implementation depends on NSPR.
+#endif
+
+namespace detail {
+
+template<typename T>
+class ProxyReleaseEvent : public mozilla::Runnable
+{
+public:
+  explicit ProxyReleaseEvent(already_AddRefed<T> aDoomed)
+  : mDoomed(aDoomed.take()) {}
+
+  NS_IMETHOD Run() override
+  {
+    NS_IF_RELEASE(mDoomed);
+    return NS_OK;
+  }
+
+private:
+  T* MOZ_OWNING_REF mDoomed;
+};
+
+template<typename T>
+void
+ProxyRelease(nsIEventTarget* aTarget, already_AddRefed<T> aDoomed, bool aAlwaysProxy)
+{
+  // Auto-managing release of the pointer.
+  RefPtr<T> doomed = aDoomed;
+  nsresult rv;
+
+  if (!doomed || !aTarget) {
+    return;
+  }
+
+  if (!aAlwaysProxy) {
+    bool onCurrentThread = false;
+    rv = aTarget->IsOnCurrentThread(&onCurrentThread);
+    if (NS_SUCCEEDED(rv) && onCurrentThread) {
+      return;
+    }
+  }
+
+  nsCOMPtr<nsIRunnable> ev = new ProxyReleaseEvent<T>(doomed.forget());
+
+  rv = aTarget->Dispatch(ev, NS_DISPATCH_NORMAL);
+  if (NS_FAILED(rv)) {
+    NS_WARNING("failed to post proxy release event, leaking!");
+    // It is better to leak the aDoomed object than risk crashing as
+    // a result of deleting it on the wrong thread.
+  }
+}
+
+template<bool nsISupportsBased>
+struct ProxyReleaseChooser
+{
+  template<typename T>
+  static void ProxyRelease(nsIEventTarget* aTarget,
+                           already_AddRefed<T> aDoomed,
+                           bool aAlwaysProxy)
+  {
+    ::detail::ProxyRelease(aTarget, mozilla::Move(aDoomed), aAlwaysProxy);
+  }
+};
+
+template<>
+struct ProxyReleaseChooser<true>
+{
+  // We need an intermediate step for handling classes with ambiguous
+  // inheritance to nsISupports.
+  template<typename T>
+  static void ProxyRelease(nsIEventTarget* aTarget,
+                           already_AddRefed<T> aDoomed,
+                           bool aAlwaysProxy)
+  {
+    ProxyReleaseISupports(aTarget, ToSupports(aDoomed.take()), aAlwaysProxy);
+  }
+
+  static void ProxyReleaseISupports(nsIEventTarget* aTarget,
+                                    nsISupports* aDoomed,
+                                    bool aAlwaysProxy);
+};
+
+} // namespace detail
+
+/**
+ * Ensures that the delete of a smart pointer occurs on the target thread.
+ *
+ * @param aTarget
+ *        the target thread where the doomed object should be released.
+ * @param aDoomed
+ *        the doomed object; the object to be released on the target thread.
+ * @param aAlwaysProxy
+ *        normally, if NS_ProxyRelease is called on the target thread, then the
+ *        doomed object will be released directly. However, if this parameter is
+ *        true, then an event will always be posted to the target thread for
+ *        asynchronous release.
+ */
+template<class T>
+inline NS_HIDDEN_(void)
+NS_ProxyRelease(nsIEventTarget* aTarget, already_AddRefed<T> aDoomed,
+                bool aAlwaysProxy = false)
+{
+  ::detail::ProxyReleaseChooser<mozilla::IsBaseOf<nsISupports, T>::value>
+    ::ProxyRelease(aTarget, mozilla::Move(aDoomed), aAlwaysProxy);
+}
+
+/**
+ * Ensures that the delete of a smart pointer occurs on the main thread.
+ *
+ * @param aDoomed
+ *        the doomed object; the object to be released on the main thread.
+ * @param aAlwaysProxy
+ *        normally, if NS_ReleaseOnMainThread is called on the main thread,
+ *        then the doomed object will be released directly. However, if this
+ *        parameter is true, then an event will always be posted to the main
+ *        thread for asynchronous release.
+ */
+template<class T>
+inline NS_HIDDEN_(void)
+NS_ReleaseOnMainThread(already_AddRefed<T> aDoomed,
+                       bool aAlwaysProxy = false)
+{
+  // NS_ProxyRelease treats a null event target as "the current thread".  So a
+  // handle on the main thread is only necessary when we're not already on the
+  // main thread or the release must happen asynchronously.
+  nsCOMPtr<nsIThread> mainThread;
+  if (!NS_IsMainThread() || aAlwaysProxy) {
+    nsresult rv = NS_GetMainThread(getter_AddRefs(mainThread));
+
+    if (NS_FAILED(rv)) {
+      MOZ_ASSERT_UNREACHABLE("Could not get main thread; leaking an object!");
+      mozilla::Unused << aDoomed.take();
+      return;
+    }
+  }
+
+  NS_ProxyRelease(mainThread, mozilla::Move(aDoomed), aAlwaysProxy);
+}
+
+/**
+ * Class to safely handle main-thread-only pointers off the main thread.
+ *
+ * Classes like XPCWrappedJS are main-thread-only, which means that it is
+ * forbidden to call methods on instances of these classes off the main thread.
+ * For various reasons (see bug 771074), this restriction recently began to
+ * apply to AddRef/Release as well.
+ *
+ * This presents a problem for consumers that wish to hold a callback alive
+ * on non-main-thread code. A common example of this is the proxy callback
+ * pattern, where non-main-thread code holds a strong-reference to the callback
+ * object, and dispatches new Runnables (also with a strong reference) to the
+ * main thread in order to execute the callback. This involves several AddRef
+ * and Release calls on the other thread, which is (now) verboten.
+ *
+ * The basic idea of this class is to introduce a layer of indirection.
+ * nsMainThreadPtrHolder is a threadsafe reference-counted class that internally
+ * maintains one strong reference to the main-thread-only object. It must be
+ * instantiated on the main thread (so that the AddRef of the underlying object
+ * happens on the main thread), but consumers may subsequently pass references
+ * to the holder anywhere they please. These references are meant to be opaque
+ * when accessed off-main-thread (assertions enforce this).
+ *
+ * The semantics of RefPtr<nsMainThreadPtrHolder<T> > would be cumbersome, so
+ * we also introduce nsMainThreadPtrHandle<T>, which is conceptually identical
+ * to the above (though it includes various convenience methods). The basic
+ * pattern is as follows.
+ *
+ * // On the main thread:
+ * nsCOMPtr<nsIFooCallback> callback = ...;
+ * nsMainThreadPtrHandle<nsIFooCallback> callbackHandle =
+ *   new nsMainThreadPtrHolder<nsIFooCallback>(callback);
+ * // Pass callbackHandle to structs/classes that might be accessed on other
+ * // threads.
+ *
+ * All structs and classes that might be accessed on other threads should store
+ * an nsMainThreadPtrHandle<T> rather than an nsCOMPtr<T>.
+ */
+template<class T>
+class nsMainThreadPtrHolder final
+{
+public:
+  // We can only acquire a pointer on the main thread. We to fail fast for
+  // threading bugs, so by default we assert if our pointer is used or acquired
+  // off-main-thread. But some consumers need to use the same pointer for
+  // multiple classes, some of which are main-thread-only and some of which
+  // aren't. So we allow them to explicitly disable this strict checking.
+  explicit nsMainThreadPtrHolder(T* aPtr, bool aStrict = true)
+    : mRawPtr(nullptr)
+    , mStrict(aStrict)
+  {
+    // We can only AddRef our pointer on the main thread, which means that the
+    // holder must be constructed on the main thread.
+    MOZ_ASSERT(!mStrict || NS_IsMainThread());
+    NS_IF_ADDREF(mRawPtr = aPtr);
+  }
+  explicit nsMainThreadPtrHolder(already_AddRefed<T> aPtr, bool aString = true)
+    : mRawPtr(aPtr.take())
+    , mStrict(aString)
+  {
+    // Since we don't need to AddRef the pointer, this constructor is safe to
+    // call on any thread.
+  }
+
+private:
+  // We can be released on any thread.
+  ~nsMainThreadPtrHolder()
+  {
+    if (NS_IsMainThread()) {
+      NS_IF_RELEASE(mRawPtr);
+    } else if (mRawPtr) {
+      NS_ReleaseOnMainThread(dont_AddRef(mRawPtr));
+    }
+  }
+
+public:
+  T* get()
+  {
+    // Nobody should be touching the raw pointer off-main-thread.
+    if (mStrict && MOZ_UNLIKELY(!NS_IsMainThread())) {
+      NS_ERROR("Can't dereference nsMainThreadPtrHolder off main thread");
+      MOZ_CRASH();
+    }
+    return mRawPtr;
+  }
+
+  bool operator==(const nsMainThreadPtrHolder<T>& aOther) const
+  {
+    return mRawPtr == aOther.mRawPtr;
+  }
+  bool operator!() const
+  {
+    return !mRawPtr;
+  }
+
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(nsMainThreadPtrHolder<T>)
+
+private:
+  // Our wrapped pointer.
+  T* mRawPtr;
+
+  // Whether to strictly enforce thread invariants in this class.
+  bool mStrict;
+
+  // Copy constructor and operator= not implemented. Once constructed, the
+  // holder is immutable.
+  T& operator=(nsMainThreadPtrHolder& aOther);
+  nsMainThreadPtrHolder(const nsMainThreadPtrHolder& aOther);
+};
+
+template<class T>
+class nsMainThreadPtrHandle
+{
+  RefPtr<nsMainThreadPtrHolder<T>> mPtr;
+
+public:
+  nsMainThreadPtrHandle() : mPtr(nullptr) {}
+  MOZ_IMPLICIT nsMainThreadPtrHandle(decltype(nullptr)) : mPtr(nullptr) {}
+  explicit nsMainThreadPtrHandle(nsMainThreadPtrHolder<T>* aHolder)
+    : mPtr(aHolder)
+  {
+  }
+  explicit nsMainThreadPtrHandle(
+      already_AddRefed<nsMainThreadPtrHolder<T>> aHolder)
+    : mPtr(aHolder)
+  {
+  }
+  nsMainThreadPtrHandle(const nsMainThreadPtrHandle& aOther)
+    : mPtr(aOther.mPtr)
+  {
+  }
+  nsMainThreadPtrHandle& operator=(const nsMainThreadPtrHandle& aOther)
+  {
+    mPtr = aOther.mPtr;
+    return *this;
+  }
+  nsMainThreadPtrHandle& operator=(nsMainThreadPtrHolder<T>* aHolder)
+  {
+    mPtr = aHolder;
+    return *this;
+  }
+
+  // These all call through to nsMainThreadPtrHolder, and thus implicitly
+  // assert that we're on the main thread. Off-main-thread consumers must treat
+  // these handles as opaque.
+  T* get()
+  {
+    if (mPtr) {
+      return mPtr.get()->get();
+    }
+    return nullptr;
+  }
+  const T* get() const
+  {
+    if (mPtr) {
+      return mPtr.get()->get();
+    }
+    return nullptr;
+  }
+
+  operator T*() { return get(); }
+  T* operator->() MOZ_NO_ADDREF_RELEASE_ON_RETURN { return get(); }
+
+  // These are safe to call on other threads with appropriate external locking.
+  bool operator==(const nsMainThreadPtrHandle<T>& aOther) const
+  {
+    if (!mPtr || !aOther.mPtr) {
+      return mPtr == aOther.mPtr;
+    }
+    return *mPtr == *aOther.mPtr;
+  }
+  bool operator!=(const nsMainThreadPtrHandle<T>& aOther) const
+  {
+    return !operator==(aOther);
+  }
+  bool operator==(decltype(nullptr)) const { return mPtr == nullptr; }
+  bool operator!=(decltype(nullptr)) const { return mPtr != nullptr; }
+  bool operator!() const {
+    return !mPtr || !*mPtr;
+  }
+};
+
+namespace mozilla {
+
+template<typename T>
+using PtrHolder = nsMainThreadPtrHolder<T>;
+
+template<typename T>
+using PtrHandle = nsMainThreadPtrHandle<T>;
+
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/glue/nsQuickSort.cpp b/xpcom/glue/nsQuickSort.cpp
new file mode 100644
index 000000000..f409b875e
--- /dev/null
+++ b/xpcom/glue/nsQuickSort.cpp
@@ -0,0 +1,187 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+
+/*-
+ * Copyright (c) 1992, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/* We need this because Solaris' version of qsort is broken and
+ * causes array bounds reads.
+ */
+
+#include <stdlib.h>
+#include "nsAlgorithm.h"
+#include "nsQuickSort.h"
+
+extern "C" {
+
+#if !defined(DEBUG) && (defined(__cplusplus) || defined(__gcc))
+# ifndef INLINE
+#  define INLINE inline
+# endif
+#else
+# define INLINE
+#endif
+
+typedef int		 cmp_t(const void *, const void *, void *);
+static INLINE char	*med3(char *, char *, char *, cmp_t *, void *);
+static INLINE void	swapfunc(char *, char *, int, int);
+
+/*
+ * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
+ */
+#define swapcode(TYPE, parmi, parmj, n) { 		\
+	long i = (n) / sizeof (TYPE); 			\
+	TYPE *pi = (TYPE *) (parmi); 			\
+	TYPE *pj = (TYPE *) (parmj); 			\
+	do { 						\
+		TYPE	t = *pi;			\
+		*pi++ = *pj;				\
+		*pj++ = t;				\
+        } while (--i > 0);				\
+}
+
+#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
+	es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
+
+static INLINE void
+swapfunc(char *a, char *b, int n, int swaptype)
+{
+	if(swaptype <= 1)
+		swapcode(long, a, b, n)
+	else
+		swapcode(char, a, b, n)
+}
+
+#define swap(a, b)					\
+	if (swaptype == 0) {				\
+		long t = *(long *)(a);			\
+		*(long *)(a) = *(long *)(b);		\
+		*(long *)(b) = t;			\
+	} else						\
+		swapfunc((char *)a, (char*)b, (int)es, swaptype)
+
+#define vecswap(a, b, n) 	if ((n) > 0) swapfunc((char *)a, (char *)b, (int)n, swaptype)
+
+static INLINE char *
+med3(char *a, char *b, char *c, cmp_t* cmp, void *data)
+{
+	return cmp(a, b, data) < 0 ?
+	       (cmp(b, c, data) < 0 ? b : (cmp(a, c, data) < 0 ? c : a ))
+              :(cmp(b, c, data) > 0 ? b : (cmp(a, c, data) < 0 ? a : c ));
+}
+
+void NS_QuickSort (
+	void *a,
+	unsigned int n,
+    unsigned int es,
+	cmp_t *cmp,
+	void *data
+    )
+{
+	char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
+	int d, r, swaptype;
+
+loop:	SWAPINIT(a, es);
+	/* Use insertion sort when input is small */
+	if (n < 7) {
+		for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
+			for (pl = pm; pl > (char *)a && cmp(pl - es, pl, data) > 0;
+			     pl -= es)
+				swap(pl, pl - es);
+		return;
+	}
+	/* Choose pivot */
+	pm = (char *)a + (n / 2) * es;
+	if (n > 7) {
+		pl = (char *)a;
+		pn = (char *)a + (n - 1) * es;
+		if (n > 40) {
+			d = (n / 8) * es;
+			pl = med3(pl, pl + d, pl + 2 * d, cmp, data);
+			pm = med3(pm - d, pm, pm + d, cmp, data);
+			pn = med3(pn - 2 * d, pn - d, pn, cmp, data);
+		}
+		pm = med3(pl, pm, pn, cmp, data);
+	}
+	swap(a, pm);
+	pa = pb = (char *)a + es;
+
+	pc = pd = (char *)a + (n - 1) * es;
+	/* loop invariants:
+	 * [a, pa) = pivot
+	 * [pa, pb) < pivot
+	 * [pb, pc + es) unprocessed
+	 * [pc + es, pd + es) > pivot
+	 * [pd + es, pn) = pivot
+	 */
+	for (;;) {
+		while (pb <= pc && (r = cmp(pb, a, data)) <= 0) {
+			if (r == 0) {
+				swap(pa, pb);
+				pa += es;
+			}
+			pb += es;
+		}
+		while (pb <= pc && (r = cmp(pc, a, data)) >= 0) {
+			if (r == 0) {
+				swap(pc, pd);
+				pd -= es;
+			}
+			pc -= es;
+		}
+		if (pb > pc)
+			break;
+		swap(pb, pc);
+		pb += es;
+		pc -= es;
+	}
+	/* Move pivot values */
+	pn = (char *)a + n * es;
+	r = XPCOM_MIN(pa - (char *)a, pb - pa);
+	vecswap(a, pb - r, r);
+	r = XPCOM_MIN<size_t>(pd - pc, pn - pd - es);
+	vecswap(pb, pn - r, r);
+	/* Recursively process partitioned items */
+	if ((r = pb - pa) > (int)es)
+        NS_QuickSort(a, r / es, es, cmp, data);
+	if ((r = pd - pc) > (int)es) {
+		/* Iterate rather than recurse to save stack space */
+		a = pn - r;
+		n = r / es;
+		goto loop;
+	}
+/*		NS_QuickSort(pn - r, r / es, es, cmp, data);*/
+}
+
+}
+
+#undef INLINE
+#undef swapcode
+#undef SWAPINIT
+#undef swap
+#undef vecswap
diff --git a/xpcom/glue/nsQuickSort.h b/xpcom/glue/nsQuickSort.h
new file mode 100644
index 000000000..e8d8ed870
--- /dev/null
+++ b/xpcom/glue/nsQuickSort.h
@@ -0,0 +1,41 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+/* We need this because Solaris' version of qsort is broken and
+ * causes array bounds reads.
+ */
+
+#ifndef nsQuickSort_h___
+#define nsQuickSort_h___
+
+#include "nscore.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Parameters:
+ *  1. the array to sort
+ *  2. the number of elements in the array
+ *  3. the size of each array element
+ *  4. comparison function taking two elements and parameter #5 and
+ *     returning an integer:
+ *      + less than zero if the first element should be before the second
+ *      + 0 if the order of the elements does not matter
+ *      + greater than zero if the second element should be before the first
+ *  5. extra data to pass to comparison function
+ */
+void NS_QuickSort(void*, unsigned int, unsigned int,
+                  int (*)(const void*, const void*, void*),
+                  void*);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* nsQuickSort_h___ */
diff --git a/xpcom/glue/nsRefPtrHashtable.h b/xpcom/glue/nsRefPtrHashtable.h
new file mode 100644
index 000000000..0ff1e0181
--- /dev/null
+++ b/xpcom/glue/nsRefPtrHashtable.h
@@ -0,0 +1,191 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsRefPtrHashtable_h__
+#define nsRefPtrHashtable_h__
+
+#include "nsBaseHashtable.h"
+#include "nsHashKeys.h"
+#include "nsAutoPtr.h"
+
+/**
+ * templated hashtable class maps keys to reference pointers.
+ * See nsBaseHashtable for complete declaration.
+ * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
+ *   for a complete specification.
+ * @param PtrType the reference-type being wrapped
+ * @see nsDataHashtable, nsClassHashtable
+ */
+template<class KeyClass, class PtrType>
+class nsRefPtrHashtable
+  : public nsBaseHashtable<KeyClass, RefPtr<PtrType>, PtrType*>
+{
+public:
+  typedef typename KeyClass::KeyType KeyType;
+  typedef PtrType* UserDataType;
+  typedef nsBaseHashtable<KeyClass, RefPtr<PtrType>, PtrType*> base_type;
+
+  nsRefPtrHashtable() {}
+  explicit nsRefPtrHashtable(uint32_t aInitLength)
+    : nsBaseHashtable<KeyClass, RefPtr<PtrType>, PtrType*>(aInitLength)
+  {
+  }
+
+  /**
+   * @copydoc nsBaseHashtable::Get
+   * @param aData This is an XPCOM getter, so aData is already_addrefed.
+   *   If the key doesn't exist, aData will be set to nullptr.
+   */
+  bool Get(KeyType aKey, UserDataType* aData) const;
+
+  /**
+   * Gets a weak reference to the hashtable entry.
+   * @param aFound If not nullptr, will be set to true if the entry is found,
+   *               to false otherwise.
+   * @return The entry, or nullptr if not found. Do not release this pointer!
+   */
+  PtrType* GetWeak(KeyType aKey, bool* aFound = nullptr) const;
+
+  // Overload Put, rather than overriding it.
+  using base_type::Put;
+
+  void Put(KeyType aKey, already_AddRefed<PtrType> aData);
+
+  MOZ_MUST_USE bool Put(KeyType aKey, already_AddRefed<PtrType> aData,
+                        const mozilla::fallible_t&);
+
+  // Overload Remove, rather than overriding it.
+  using base_type::Remove;
+
+  /**
+   * Remove the data for the associated key, swapping the current value into
+   * pData, thereby avoiding calls to AddRef and Release.
+   * @param aKey the key to remove from the hashtable
+   * @param aData This is an XPCOM getter, so aData is already_addrefed.
+   *   If the key doesn't exist, aData will be set to nullptr. Must be non-null.
+   */
+  bool Remove(KeyType aKey, UserDataType* aData);
+};
+
+template<typename K, typename T>
+inline void
+ImplCycleCollectionUnlink(nsRefPtrHashtable<K, T>& aField)
+{
+  aField.Clear();
+}
+
+template<typename K, typename T>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            nsRefPtrHashtable<K, T>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  for (auto iter = aField.ConstIter(); !iter.Done(); iter.Next()) {
+    CycleCollectionNoteChild(aCallback, iter.UserData(), aName, aFlags);
+  }
+}
+
+//
+// nsRefPtrHashtable definitions
+//
+
+template<class KeyClass, class PtrType>
+bool
+nsRefPtrHashtable<KeyClass, PtrType>::Get(KeyType aKey,
+                                          UserDataType* aRefPtr) const
+{
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+
+  if (ent) {
+    if (aRefPtr) {
+      *aRefPtr = ent->mData;
+
+      NS_IF_ADDREF(*aRefPtr);
+    }
+
+    return true;
+  }
+
+  // if the key doesn't exist, set *aRefPtr to null
+  // so that it is a valid XPCOM getter
+  if (aRefPtr) {
+    *aRefPtr = nullptr;
+  }
+
+  return false;
+}
+
+template<class KeyClass, class PtrType>
+PtrType*
+nsRefPtrHashtable<KeyClass, PtrType>::GetWeak(KeyType aKey, bool* aFound) const
+{
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+
+  if (ent) {
+    if (aFound) {
+      *aFound = true;
+    }
+
+    return ent->mData;
+  }
+
+  // Key does not exist, return nullptr and set aFound to false
+  if (aFound) {
+    *aFound = false;
+  }
+
+  return nullptr;
+}
+
+template<class KeyClass, class PtrType>
+void
+nsRefPtrHashtable<KeyClass, PtrType>::Put(KeyType aKey,
+                                          already_AddRefed<PtrType> aData)
+{
+  if (!Put(aKey, mozilla::Move(aData), mozilla::fallible)) {
+    NS_ABORT_OOM(this->mTable.EntrySize() * this->mTable.EntryCount());
+  }
+}
+
+template<class KeyClass, class PtrType>
+bool
+nsRefPtrHashtable<KeyClass, PtrType>::Put(KeyType aKey,
+                                          already_AddRefed<PtrType> aData,
+                                          const mozilla::fallible_t&)
+{
+  typename base_type::EntryType* ent = this->PutEntry(aKey);
+
+  if (!ent) {
+    return false;
+  }
+
+  ent->mData = aData;
+
+  return true;
+}
+
+template<class KeyClass, class PtrType>
+bool
+nsRefPtrHashtable<KeyClass, PtrType>::Remove(KeyType aKey,
+                                             UserDataType* aRefPtr)
+{
+  MOZ_ASSERT(aRefPtr);
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+
+  if (ent) {
+    ent->mData.forget(aRefPtr);
+    this->Remove(aKey);
+    return true;
+  }
+
+  // If the key doesn't exist, set *aRefPtr to null
+  // so that it is a valid XPCOM getter.
+  *aRefPtr = nullptr;
+  return false;
+}
+
+#endif // nsRefPtrHashtable_h__
diff --git a/xpcom/glue/nsServiceManagerUtils.h b/xpcom/glue/nsServiceManagerUtils.h
new file mode 100644
index 000000000..d1ea408a2
--- /dev/null
+++ b/xpcom/glue/nsServiceManagerUtils.h
@@ -0,0 +1,94 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsServiceManagerUtils_h__
+#define nsServiceManagerUtils_h__
+
+#include "nsIServiceManager.h"
+#include "nsCOMPtr.h"
+
+inline const nsGetServiceByCID
+do_GetService(const nsCID& aCID)
+{
+  return nsGetServiceByCID(aCID);
+}
+
+inline const nsGetServiceByCIDWithError
+do_GetService(const nsCID& aCID, nsresult* aError)
+{
+  return nsGetServiceByCIDWithError(aCID, aError);
+}
+
+inline const nsGetServiceByContractID
+do_GetService(const char* aContractID)
+{
+  return nsGetServiceByContractID(aContractID);
+}
+
+inline const nsGetServiceByContractIDWithError
+do_GetService(const char* aContractID, nsresult* aError)
+{
+  return nsGetServiceByContractIDWithError(aContractID, aError);
+}
+
+class MOZ_STACK_CLASS nsGetServiceFromCategory final : public nsCOMPtr_helper
+{
+public:
+  nsGetServiceFromCategory(const char* aCategory, const char* aEntry,
+                           nsresult* aErrorPtr)
+    : mCategory(aCategory)
+    , mEntry(aEntry)
+    , mErrorPtr(aErrorPtr)
+  {
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID&, void**) const
+    override;
+protected:
+  const char*                 mCategory;
+  const char*                 mEntry;
+  nsresult*                   mErrorPtr;
+};
+
+inline const nsGetServiceFromCategory
+do_GetServiceFromCategory(const char* aCategory, const char* aEntry,
+                          nsresult* aError = 0)
+{
+  return nsGetServiceFromCategory(aCategory, aEntry, aError);
+}
+
+nsresult CallGetService(const nsCID& aClass, const nsIID& aIID, void** aResult);
+
+nsresult CallGetService(const char* aContractID, const nsIID& aIID,
+                        void** aResult);
+
+// type-safe shortcuts for calling |GetService|
+template<class DestinationType>
+inline nsresult
+CallGetService(const nsCID& aClass,
+               DestinationType** aDestination)
+{
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return CallGetService(aClass,
+                        NS_GET_TEMPLATE_IID(DestinationType),
+                        reinterpret_cast<void**>(aDestination));
+}
+
+template<class DestinationType>
+inline nsresult
+CallGetService(const char* aContractID,
+               DestinationType** aDestination)
+{
+  NS_PRECONDITION(aContractID, "null parameter");
+  NS_PRECONDITION(aDestination, "null parameter");
+
+  return CallGetService(aContractID,
+                        NS_GET_TEMPLATE_IID(DestinationType),
+                        reinterpret_cast<void**>(aDestination));
+}
+
+#endif
diff --git a/xpcom/glue/nsStringAPI.cpp b/xpcom/glue/nsStringAPI.cpp
new file mode 100644
index 000000000..e5114a149
--- /dev/null
+++ b/xpcom/glue/nsStringAPI.cpp
@@ -0,0 +1,1304 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nscore.h"
+#include "nsCRTGlue.h"
+#include "prprf.h"
+#include "nsStringAPI.h"
+#include "nsXPCOMStrings.h"
+#include "nsDebug.h"
+
+#include "mozilla/Sprintf.h"
+
+#include <stdio.h>
+
+// nsAString
+
+uint32_t
+nsAString::BeginReading(const char_type** aBegin, const char_type** aEnd) const
+{
+  uint32_t len = NS_StringGetData(*this, aBegin);
+  if (aEnd) {
+    *aEnd = *aBegin + len;
+  }
+
+  return len;
+}
+
+const nsAString::char_type*
+nsAString::BeginReading() const
+{
+  const char_type* data;
+  NS_StringGetData(*this, &data);
+  return data;
+}
+
+const nsAString::char_type*
+nsAString::EndReading() const
+{
+  const char_type* data;
+  uint32_t len = NS_StringGetData(*this, &data);
+  return data + len;
+}
+
+uint32_t
+nsAString::BeginWriting(char_type** aBegin, char_type** aEnd, uint32_t aNewSize)
+{
+  uint32_t len = NS_StringGetMutableData(*this, aNewSize, aBegin);
+  if (aEnd) {
+    *aEnd = *aBegin + len;
+  }
+
+  return len;
+}
+
+nsAString::char_type*
+nsAString::BeginWriting(uint32_t aLen)
+{
+  char_type* data;
+  NS_StringGetMutableData(*this, aLen, &data);
+  return data;
+}
+
+nsAString::char_type*
+nsAString::EndWriting()
+{
+  char_type* data;
+  uint32_t len = NS_StringGetMutableData(*this, UINT32_MAX, &data);
+  return data + len;
+}
+
+bool
+nsAString::SetLength(uint32_t aLen)
+{
+  char_type* data;
+  NS_StringGetMutableData(*this, aLen, &data);
+  return data != nullptr;
+}
+
+void
+nsAString::AssignLiteral(const char* aStr)
+{
+  uint32_t len = strlen(aStr);
+  char16_t* buf = BeginWriting(len);
+  if (!buf) {
+    return;
+  }
+
+  for (; *aStr; ++aStr, ++buf) {
+    *buf = *aStr;
+  }
+}
+
+void
+nsAString::AppendLiteral(const char* aASCIIStr)
+{
+  uint32_t appendLen = strlen(aASCIIStr);
+
+  uint32_t thisLen = Length();
+  char16_t* begin;
+  char16_t* end;
+  BeginWriting(&begin, &end, appendLen + thisLen);
+  if (!begin) {
+    return;
+  }
+
+  for (begin += thisLen; begin < end; ++begin, ++aASCIIStr) {
+    *begin = *aASCIIStr;
+  }
+}
+
+void
+nsAString::StripChars(const char* aSet)
+{
+  nsString copy(*this);
+
+  const char_type* source;
+  const char_type* sourceEnd;
+  copy.BeginReading(&source, &sourceEnd);
+
+  char_type* dest;
+  BeginWriting(&dest);
+  if (!dest) {
+    return;
+  }
+
+  char_type* curDest = dest;
+
+  for (; source < sourceEnd; ++source) {
+    const char* test;
+    for (test = aSet; *test; ++test) {
+      if (*source == char_type(*test)) {
+        break;
+      }
+    }
+
+    if (!*test) {
+      // not stripped, copy this char
+      *curDest = *source;
+      ++curDest;
+    }
+  }
+
+  SetLength(curDest - dest);
+}
+
+void
+nsAString::Trim(const char* aSet, bool aLeading, bool aTrailing)
+{
+  NS_ASSERTION(aLeading || aTrailing, "Ineffective Trim");
+
+  const char16_t* start;
+  const char16_t* end;
+  uint32_t cutLen;
+
+  if (aLeading) {
+    BeginReading(&start, &end);
+    for (cutLen = 0; start < end; ++start, ++cutLen) {
+      const char* test;
+      for (test = aSet; *test; ++test) {
+        if (*test == *start) {
+          break;
+        }
+      }
+      if (!*test) {
+        break;
+      }
+    }
+    if (cutLen) {
+      NS_StringCutData(*this, 0, cutLen);
+    }
+  }
+  if (aTrailing) {
+    uint32_t len = BeginReading(&start, &end);
+    --end;
+    for (cutLen = 0; end >= start; --end, ++cutLen) {
+      const char* test;
+      for (test = aSet; *test; ++test) {
+        if (*test == *end) {
+          break;
+        }
+      }
+      if (!*test) {
+        break;
+      }
+    }
+    if (cutLen) {
+      NS_StringCutData(*this, len - cutLen, cutLen);
+    }
+  }
+}
+
+int32_t
+nsAString::DefaultComparator(const char_type* aStrA, const char_type* aStrB,
+                             uint32_t aLen)
+{
+  for (const char_type* end = aStrA + aLen; aStrA < end; ++aStrA, ++aStrB) {
+    if (*aStrA == *aStrB) {
+      continue;
+    }
+
+    return *aStrA < *aStrB ? -1 : 1;
+  }
+
+  return 0;
+}
+
+int32_t
+nsAString::Compare(const char_type* aOther, ComparatorFunc aComparator) const
+{
+  const char_type* cself;
+  uint32_t selflen = NS_StringGetData(*this, &cself);
+  uint32_t otherlen = NS_strlen(aOther);
+  uint32_t comparelen = selflen <= otherlen ? selflen : otherlen;
+
+  int32_t result = aComparator(cself, aOther, comparelen);
+  if (result == 0) {
+    if (selflen < otherlen) {
+      return -1;
+    } else if (selflen > otherlen) {
+      return 1;
+    }
+  }
+  return result;
+}
+
+int32_t
+nsAString::Compare(const self_type& aOther, ComparatorFunc aComparator) const
+{
+  const char_type* cself;
+  const char_type* cother;
+  uint32_t selflen = NS_StringGetData(*this, &cself);
+  uint32_t otherlen = NS_StringGetData(aOther, &cother);
+  uint32_t comparelen = selflen <= otherlen ? selflen : otherlen;
+
+  int32_t result = aComparator(cself, cother, comparelen);
+  if (result == 0) {
+    if (selflen < otherlen) {
+      return -1;
+    } else if (selflen > otherlen) {
+      return 1;
+    }
+  }
+  return result;
+}
+
+bool
+nsAString::Equals(const char_type* aOther, ComparatorFunc aComparator) const
+{
+  const char_type* cself;
+  uint32_t selflen = NS_StringGetData(*this, &cself);
+  uint32_t otherlen = NS_strlen(aOther);
+
+  if (selflen != otherlen) {
+    return false;
+  }
+
+  return aComparator(cself, aOther, selflen) == 0;
+}
+
+bool
+nsAString::Equals(const self_type& aOther, ComparatorFunc aComparator) const
+{
+  const char_type* cself;
+  const char_type* cother;
+  uint32_t selflen = NS_StringGetData(*this, &cself);
+  uint32_t otherlen = NS_StringGetData(aOther, &cother);
+
+  if (selflen != otherlen) {
+    return false;
+  }
+
+  return aComparator(cself, cother, selflen) == 0;
+}
+
+bool
+nsAString::EqualsLiteral(const char* aASCIIString) const
+{
+  const char16_t* begin;
+  const char16_t* end;
+  BeginReading(&begin, &end);
+
+  for (; begin < end; ++begin, ++aASCIIString) {
+    if (!*aASCIIString || !NS_IsAscii(*begin) ||
+        (char)*begin != *aASCIIString) {
+      return false;
+    }
+  }
+
+  return *aASCIIString == '\0';
+}
+
+bool
+nsAString::LowerCaseEqualsLiteral(const char* aASCIIString) const
+{
+  const char16_t* begin;
+  const char16_t* end;
+  BeginReading(&begin, &end);
+
+  for (; begin < end; ++begin, ++aASCIIString) {
+    if (!*aASCIIString || !NS_IsAscii(*begin) ||
+        NS_ToLower((char)*begin) != *aASCIIString) {
+      return false;
+    }
+  }
+
+  return *aASCIIString == '\0';
+}
+
+int32_t
+nsAString::Find(const self_type& aStr, uint32_t aOffset,
+                ComparatorFunc aComparator) const
+{
+  const char_type* begin;
+  const char_type* end;
+  uint32_t selflen = BeginReading(&begin, &end);
+
+  if (aOffset > selflen) {
+    return -1;
+  }
+
+  const char_type* other;
+  uint32_t otherlen = aStr.BeginReading(&other);
+
+  if (otherlen > selflen - aOffset) {
+    return -1;
+  }
+
+  // We want to stop searching otherlen characters before the end of the string
+  end -= otherlen;
+
+  for (const char_type* cur = begin + aOffset; cur <= end; ++cur) {
+    if (!aComparator(cur, other, otherlen)) {
+      return cur - begin;
+    }
+  }
+  return -1;
+}
+
+static bool
+ns_strnmatch(const char16_t* aStr, const char* aSubstring, uint32_t aLen)
+{
+  for (; aLen; ++aStr, ++aSubstring, --aLen) {
+    if (!NS_IsAscii(*aStr)) {
+      return false;
+    }
+
+    if ((char)*aStr != *aSubstring) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+static bool
+ns_strnimatch(const char16_t* aStr, const char* aSubstring, uint32_t aLen)
+{
+  for (; aLen; ++aStr, ++aSubstring, --aLen) {
+    if (!NS_IsAscii(*aStr)) {
+      return false;
+    }
+
+    if (NS_ToLower((char)*aStr) != NS_ToLower(*aSubstring)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+int32_t
+nsAString::Find(const char* aStr, uint32_t aOffset, bool aIgnoreCase) const
+{
+  bool (*match)(const char16_t*, const char*, uint32_t) =
+    aIgnoreCase ? ns_strnimatch : ns_strnmatch;
+
+  const char_type* begin;
+  const char_type* end;
+  uint32_t selflen = BeginReading(&begin, &end);
+
+  if (aOffset > selflen) {
+    return -1;
+  }
+
+  uint32_t otherlen = strlen(aStr);
+
+  if (otherlen > selflen - aOffset) {
+    return -1;
+  }
+
+  // We want to stop searching otherlen characters before the end of the string
+  end -= otherlen;
+
+  for (const char_type* cur = begin + aOffset; cur <= end; ++cur) {
+    if (match(cur, aStr, otherlen)) {
+      return cur - begin;
+    }
+  }
+  return -1;
+}
+
+int32_t
+nsAString::RFind(const self_type& aStr, int32_t aOffset,
+                 ComparatorFunc aComparator) const
+{
+  const char_type* begin;
+  const char_type* end;
+  uint32_t selflen = BeginReading(&begin, &end);
+
+  const char_type* other;
+  uint32_t otherlen = aStr.BeginReading(&other);
+
+  if (selflen < otherlen) {
+    return -1;
+  }
+
+  if (aOffset < 0 || uint32_t(aOffset) > (selflen - otherlen)) {
+    end -= otherlen;
+  } else {
+    end = begin + aOffset;
+  }
+
+  for (const char_type* cur = end; cur >= begin; --cur) {
+    if (!aComparator(cur, other, otherlen)) {
+      return cur - begin;
+    }
+  }
+  return -1;
+}
+
+int32_t
+nsAString::RFind(const char* aStr, int32_t aOffset, bool aIgnoreCase) const
+{
+  bool (*match)(const char16_t*, const char*, uint32_t) =
+    aIgnoreCase ? ns_strnimatch : ns_strnmatch;
+
+  const char_type* begin;
+  const char_type* end;
+  uint32_t selflen = BeginReading(&begin, &end);
+  uint32_t otherlen = strlen(aStr);
+
+  if (selflen < otherlen) {
+    return -1;
+  }
+
+  if (aOffset < 0 || uint32_t(aOffset) > (selflen - otherlen)) {
+    end -= otherlen;
+  } else {
+    end = begin + aOffset;
+  }
+
+  for (const char_type* cur = end; cur >= begin; --cur) {
+    if (match(cur, aStr, otherlen)) {
+      return cur - begin;
+    }
+  }
+  return -1;
+}
+
+int32_t
+nsAString::FindChar(char_type aChar, uint32_t aOffset) const
+{
+  const char_type* start;
+  const char_type* end;
+  uint32_t len = BeginReading(&start, &end);
+  if (aOffset > len) {
+    return -1;
+  }
+
+  const char_type* cur;
+
+  for (cur = start + aOffset; cur < end; ++cur) {
+    if (*cur == aChar) {
+      return cur - start;
+    }
+  }
+
+  return -1;
+}
+
+int32_t
+nsAString::RFindChar(char_type aChar) const
+{
+  const char16_t* start;
+  const char16_t* end;
+  BeginReading(&start, &end);
+
+  do {
+    --end;
+
+    if (*end == aChar) {
+      return end - start;
+    }
+
+  } while (end >= start);
+
+  return -1;
+}
+
+void
+nsAString::AppendInt(int aInt, int32_t aRadix)
+{
+  const char* fmt;
+  switch (aRadix) {
+    case 8:
+      fmt = "%o";
+      break;
+
+    case 10:
+      fmt = "%d";
+      break;
+
+    case 16:
+      fmt = "%x";
+      break;
+
+    default:
+      NS_ERROR("Unrecognized radix");
+      fmt = "";
+  }
+
+  char buf[20];
+  int len = SprintfLiteral(buf, fmt, aInt);
+  Append(NS_ConvertASCIItoUTF16(buf, len));
+}
+
+// Strings
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+int32_t
+nsAString::ToInteger(nsresult* aErrorCode, uint32_t aRadix) const
+{
+  NS_ConvertUTF16toUTF8 narrow(*this);
+
+  const char* fmt;
+  switch (aRadix) {
+    case 10:
+      fmt = "%i";
+      break;
+
+    case 16:
+      fmt = "%x";
+      break;
+
+    default:
+      NS_ERROR("Unrecognized radix!");
+      *aErrorCode = NS_ERROR_INVALID_ARG;
+      return 0;
+  }
+
+  int32_t result = 0;
+  if (PR_sscanf(narrow.get(), fmt, &result) == 1) {
+    *aErrorCode = NS_OK;
+  } else {
+    *aErrorCode = NS_ERROR_FAILURE;
+  }
+
+  return result;
+}
+
+int64_t
+nsAString::ToInteger64(nsresult* aErrorCode, uint32_t aRadix) const
+{
+  NS_ConvertUTF16toUTF8 narrow(*this);
+
+  const char* fmt;
+  switch (aRadix) {
+    case 10:
+      fmt = "%lli";
+      break;
+
+    case 16:
+      fmt = "%llx";
+      break;
+
+    default:
+      NS_ERROR("Unrecognized radix!");
+      *aErrorCode = NS_ERROR_INVALID_ARG;
+      return 0;
+  }
+
+  int64_t result = 0;
+  if (PR_sscanf(narrow.get(), fmt, &result) == 1) {
+    *aErrorCode = NS_OK;
+  } else {
+    *aErrorCode = NS_ERROR_FAILURE;
+  }
+
+  return result;
+}
+#endif // XPCOM_GLUE_AVOID_NSPR
+
+// nsACString
+
+uint32_t
+nsACString::BeginReading(const char_type** aBegin, const char_type** aEnd) const
+{
+  uint32_t len = NS_CStringGetData(*this, aBegin);
+  if (aEnd) {
+    *aEnd = *aBegin + len;
+  }
+
+  return len;
+}
+
+const nsACString::char_type*
+nsACString::BeginReading() const
+{
+  const char_type* data;
+  NS_CStringGetData(*this, &data);
+  return data;
+}
+
+const nsACString::char_type*
+nsACString::EndReading() const
+{
+  const char_type* data;
+  uint32_t len = NS_CStringGetData(*this, &data);
+  return data + len;
+}
+
+uint32_t
+nsACString::BeginWriting(char_type** aBegin, char_type** aEnd,
+                         uint32_t aNewSize)
+{
+  uint32_t len = NS_CStringGetMutableData(*this, aNewSize, aBegin);
+  if (aEnd) {
+    *aEnd = *aBegin + len;
+  }
+
+  return len;
+}
+
+nsACString::char_type*
+nsACString::BeginWriting(uint32_t aLen)
+{
+  char_type* data;
+  NS_CStringGetMutableData(*this, aLen, &data);
+  return data;
+}
+
+nsACString::char_type*
+nsACString::EndWriting()
+{
+  char_type* data;
+  uint32_t len = NS_CStringGetMutableData(*this, UINT32_MAX, &data);
+  return data + len;
+}
+
+bool
+nsACString::SetLength(uint32_t aLen)
+{
+  char_type* data;
+  NS_CStringGetMutableData(*this, aLen, &data);
+  return data != nullptr;
+}
+
+void
+nsACString::StripChars(const char* aSet)
+{
+  nsCString copy(*this);
+
+  const char_type* source;
+  const char_type* sourceEnd;
+  copy.BeginReading(&source, &sourceEnd);
+
+  char_type* dest;
+  BeginWriting(&dest);
+  if (!dest) {
+    return;
+  }
+
+  char_type* curDest = dest;
+
+  for (; source < sourceEnd; ++source) {
+    const char* test;
+    for (test = aSet; *test; ++test) {
+      if (*source == char_type(*test)) {
+        break;
+      }
+    }
+
+    if (!*test) {
+      // not stripped, copy this char
+      *curDest = *source;
+      ++curDest;
+    }
+  }
+
+  SetLength(curDest - dest);
+}
+
+void
+nsACString::Trim(const char* aSet, bool aLeading, bool aTrailing)
+{
+  NS_ASSERTION(aLeading || aTrailing, "Ineffective Trim");
+
+  const char* start;
+  const char* end;
+  uint32_t cutLen;
+
+  if (aLeading) {
+    BeginReading(&start, &end);
+    for (cutLen = 0; start < end; ++start, ++cutLen) {
+      const char* test;
+      for (test = aSet; *test; ++test) {
+        if (*test == *start) {
+          break;
+        }
+      }
+      if (!*test) {
+        break;
+      }
+    }
+    if (cutLen) {
+      NS_CStringCutData(*this, 0, cutLen);
+    }
+  }
+  if (aTrailing) {
+    uint32_t len = BeginReading(&start, &end);
+    --end;
+    for (cutLen = 0; end >= start; --end, ++cutLen) {
+      const char* test;
+      for (test = aSet; *test; ++test) {
+        if (*test == *end) {
+          break;
+        }
+      }
+      if (!*test) {
+        break;
+      }
+    }
+    if (cutLen) {
+      NS_CStringCutData(*this, len - cutLen, cutLen);
+    }
+  }
+}
+
+int32_t
+nsACString::DefaultComparator(const char_type* aStrA, const char_type* aStrB,
+                              uint32_t aLen)
+{
+  return memcmp(aStrA, aStrB, aLen);
+}
+
+int32_t
+nsACString::Compare(const char_type* aOther, ComparatorFunc aComparator) const
+{
+  const char_type* cself;
+  uint32_t selflen = NS_CStringGetData(*this, &cself);
+  uint32_t otherlen = strlen(aOther);
+  uint32_t comparelen = selflen <= otherlen ? selflen : otherlen;
+
+  int32_t result = aComparator(cself, aOther, comparelen);
+  if (result == 0) {
+    if (selflen < otherlen) {
+      return -1;
+    } else if (selflen > otherlen) {
+      return 1;
+    }
+  }
+  return result;
+}
+
+int32_t
+nsACString::Compare(const self_type& aOther, ComparatorFunc aComparator) const
+{
+  const char_type* cself;
+  const char_type* cother;
+  uint32_t selflen = NS_CStringGetData(*this, &cself);
+  uint32_t otherlen = NS_CStringGetData(aOther, &cother);
+  uint32_t comparelen = selflen <= otherlen ? selflen : otherlen;
+
+  int32_t result = aComparator(cself, cother, comparelen);
+  if (result == 0) {
+    if (selflen < otherlen) {
+      return -1;
+    } else if (selflen > otherlen) {
+      return 1;
+    }
+  }
+  return result;
+}
+
+bool
+nsACString::Equals(const char_type* aOther, ComparatorFunc aComparator) const
+{
+  const char_type* cself;
+  uint32_t selflen = NS_CStringGetData(*this, &cself);
+  uint32_t otherlen = strlen(aOther);
+
+  if (selflen != otherlen) {
+    return false;
+  }
+
+  return aComparator(cself, aOther, selflen) == 0;
+}
+
+bool
+nsACString::Equals(const self_type& aOther, ComparatorFunc aComparator) const
+{
+  const char_type* cself;
+  const char_type* cother;
+  uint32_t selflen = NS_CStringGetData(*this, &cself);
+  uint32_t otherlen = NS_CStringGetData(aOther, &cother);
+
+  if (selflen != otherlen) {
+    return false;
+  }
+
+  return aComparator(cself, cother, selflen) == 0;
+}
+
+int32_t
+nsACString::Find(const self_type& aStr, uint32_t aOffset,
+                 ComparatorFunc aComparator) const
+{
+  const char_type* begin;
+  const char_type* end;
+  uint32_t selflen = BeginReading(&begin, &end);
+
+  if (aOffset > selflen) {
+    return -1;
+  }
+
+  const char_type* other;
+  uint32_t otherlen = aStr.BeginReading(&other);
+
+  if (otherlen > selflen - aOffset) {
+    return -1;
+  }
+
+  // We want to stop searching otherlen characters before the end of the string
+  end -= otherlen;
+
+  for (const char_type* cur = begin + aOffset; cur <= end; ++cur) {
+    if (!aComparator(cur, other, otherlen)) {
+      return cur - begin;
+    }
+  }
+  return -1;
+}
+
+int32_t
+nsACString::Find(const char_type* aStr, ComparatorFunc aComparator) const
+{
+  return Find(aStr, strlen(aStr), aComparator);
+}
+
+int32_t
+nsACString::Find(const char_type* aStr, uint32_t aLen,
+                 ComparatorFunc aComparator) const
+{
+  const char_type* begin;
+  const char_type* end;
+  uint32_t selflen = BeginReading(&begin, &end);
+
+  if (aLen == 0) {
+    NS_WARNING("Searching for zero-length string.");
+    return -1;
+  }
+
+  if (aLen > selflen) {
+    return -1;
+  }
+
+  // We want to stop searching otherlen characters before the end of the string
+  end -= aLen;
+
+  for (const char_type* cur = begin; cur <= end; ++cur) {
+    if (!aComparator(cur, aStr, aLen)) {
+      return cur - begin;
+    }
+  }
+  return -1;
+}
+
+int32_t
+nsACString::RFind(const self_type& aStr, int32_t aOffset,
+                  ComparatorFunc aComparator) const
+{
+  const char_type* begin;
+  const char_type* end;
+  uint32_t selflen = BeginReading(&begin, &end);
+
+  const char_type* other;
+  uint32_t otherlen = aStr.BeginReading(&other);
+
+  if (selflen < otherlen) {
+    return -1;
+  }
+
+  if (aOffset < 0 || uint32_t(aOffset) > (selflen - otherlen)) {
+    end -= otherlen;
+  } else {
+    end = begin + aOffset;
+  }
+
+  for (const char_type* cur = end; cur >= begin; --cur) {
+    if (!aComparator(cur, other, otherlen)) {
+      return cur - begin;
+    }
+  }
+  return -1;
+}
+
+int32_t
+nsACString::RFind(const char_type* aStr, ComparatorFunc aComparator) const
+{
+  return RFind(aStr, strlen(aStr), aComparator);
+}
+
+int32_t
+nsACString::RFind(const char_type* aStr, int32_t aLen,
+                  ComparatorFunc aComparator) const
+{
+  const char_type* begin;
+  const char_type* end;
+  uint32_t selflen = BeginReading(&begin, &end);
+
+  if (aLen <= 0) {
+    NS_WARNING("Searching for zero-length string.");
+    return -1;
+  }
+
+  if (uint32_t(aLen) > selflen) {
+    return -1;
+  }
+
+  // We want to start searching otherlen characters before the end of the string
+  end -= aLen;
+
+  for (const char_type* cur = end; cur >= begin; --cur) {
+    if (!aComparator(cur, aStr, aLen)) {
+      return cur - begin;
+    }
+  }
+  return -1;
+}
+
+int32_t
+nsACString::FindChar(char_type aChar, uint32_t aOffset) const
+{
+  const char_type* start;
+  const char_type* end;
+  uint32_t len = BeginReading(&start, &end);
+  if (aOffset > len) {
+    return -1;
+  }
+
+  const char_type* cur;
+
+  for (cur = start + aOffset; cur < end; ++cur) {
+    if (*cur == aChar) {
+      return cur - start;
+    }
+  }
+
+  return -1;
+}
+
+int32_t
+nsACString::RFindChar(char_type aChar) const
+{
+  const char* start;
+  const char* end;
+  BeginReading(&start, &end);
+
+  for (; end >= start; --end) {
+    if (*end == aChar) {
+      return end - start;
+    }
+  }
+
+  return -1;
+}
+
+void
+nsACString::AppendInt(int aInt, int32_t aRadix)
+{
+  const char* fmt;
+  switch (aRadix) {
+    case 8:
+      fmt = "%o";
+      break;
+
+    case 10:
+      fmt = "%d";
+      break;
+
+    case 16:
+      fmt = "%x";
+      break;
+
+    default:
+      NS_ERROR("Unrecognized radix");
+      fmt = "";
+  }
+
+  char buf[20];
+  int len = SprintfLiteral(buf, fmt, aInt);
+  Append(buf, len);
+}
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+int32_t
+nsACString::ToInteger(nsresult* aErrorCode, uint32_t aRadix) const
+{
+  const char* fmt;
+  switch (aRadix) {
+    case 10:
+      fmt = "%i";
+      break;
+
+    case 16:
+      fmt = "%x";
+      break;
+
+    default:
+      NS_ERROR("Unrecognized radix!");
+      *aErrorCode = NS_ERROR_INVALID_ARG;
+      return 0;
+  }
+
+  int32_t result = 0;
+  if (PR_sscanf(nsCString(*this).get(), fmt, &result) == 1) {
+    *aErrorCode = NS_OK;
+  } else {
+    *aErrorCode = NS_ERROR_FAILURE;
+  }
+
+  return result;
+}
+
+int64_t
+nsACString::ToInteger64(nsresult* aErrorCode, uint32_t aRadix) const
+{
+  const char* fmt;
+  switch (aRadix) {
+    case 10:
+      fmt = "%lli";
+      break;
+
+    case 16:
+      fmt = "%llx";
+      break;
+
+    default:
+      NS_ERROR("Unrecognized radix!");
+      *aErrorCode = NS_ERROR_INVALID_ARG;
+      return 0;
+  }
+
+  int64_t result = 0;
+  if (PR_sscanf(nsCString(*this).get(), fmt, &result) == 1) {
+    *aErrorCode = NS_OK;
+  } else {
+    *aErrorCode = NS_ERROR_FAILURE;
+  }
+
+  return result;
+}
+#endif // XPCOM_GLUE_AVOID_NSPR
+
+// Substrings
+
+nsDependentSubstring::nsDependentSubstring(const abstract_string_type& aStr,
+                                           uint32_t aStartPos)
+{
+  const char16_t* data;
+  uint32_t len = NS_StringGetData(aStr, &data);
+
+  if (aStartPos > len) {
+    aStartPos = len;
+  }
+
+  NS_StringContainerInit2(*this, data + aStartPos, len - aStartPos,
+                          NS_STRING_CONTAINER_INIT_DEPEND |
+                          NS_STRING_CONTAINER_INIT_SUBSTRING);
+}
+
+nsDependentSubstring::nsDependentSubstring(const abstract_string_type& aStr,
+                                           uint32_t aStartPos,
+                                           uint32_t aLength)
+{
+  const char16_t* data;
+  uint32_t len = NS_StringGetData(aStr, &data);
+
+  if (aStartPos > len) {
+    aStartPos = len;
+  }
+
+  if (aStartPos + aLength > len) {
+    aLength = len - aStartPos;
+  }
+
+  NS_StringContainerInit2(*this, data + aStartPos, aLength,
+                          NS_STRING_CONTAINER_INIT_DEPEND |
+                            NS_STRING_CONTAINER_INIT_SUBSTRING);
+}
+
+nsDependentCSubstring::nsDependentCSubstring(const abstract_string_type& aStr,
+                                             uint32_t aStartPos)
+{
+  const char* data;
+  uint32_t len = NS_CStringGetData(aStr, &data);
+
+  if (aStartPos > len) {
+    aStartPos = len;
+  }
+
+  NS_CStringContainerInit2(*this, data + aStartPos, len - aStartPos,
+                           NS_CSTRING_CONTAINER_INIT_DEPEND |
+                           NS_CSTRING_CONTAINER_INIT_SUBSTRING);
+}
+
+nsDependentCSubstring::nsDependentCSubstring(const abstract_string_type& aStr,
+                                             uint32_t aStartPos,
+                                             uint32_t aLength)
+{
+  const char* data;
+  uint32_t len = NS_CStringGetData(aStr, &data);
+
+  if (aStartPos > len) {
+    aStartPos = len;
+  }
+
+  if (aStartPos + aLength > len) {
+    aLength = len - aStartPos;
+  }
+
+  NS_CStringContainerInit2(*this, data + aStartPos, aLength,
+                           NS_CSTRING_CONTAINER_INIT_DEPEND |
+                           NS_CSTRING_CONTAINER_INIT_SUBSTRING);
+}
+
+// Utils
+
+char*
+ToNewUTF8String(const nsAString& aSource)
+{
+  nsCString temp;
+  CopyUTF16toUTF8(aSource, temp);
+  return NS_CStringCloneData(temp);
+}
+
+void
+CompressWhitespace(nsAString& aString)
+{
+  char16_t* start;
+  uint32_t len = NS_StringGetMutableData(aString, UINT32_MAX, &start);
+  char16_t* end = start + len;
+  char16_t* from = start;
+  char16_t* to = start;
+
+  // Skip any leading whitespace
+  while (from < end && NS_IsAsciiWhitespace(*from)) {
+    from++;
+  }
+
+  while (from < end) {
+    char16_t theChar = *from++;
+
+    if (NS_IsAsciiWhitespace(theChar)) {
+      // We found a whitespace char, so skip over any more
+      while (from < end && NS_IsAsciiWhitespace(*from)) {
+        from++;
+      }
+
+      // Turn all whitespace into spaces
+      theChar = ' ';
+    }
+
+    *to++ = theChar;
+  }
+
+  // Drop any trailing space
+  if (to > start && to[-1] == ' ') {
+    to--;
+  }
+
+  // Re-terminate the string
+  *to = '\0';
+
+  // Set the new length
+  aString.SetLength(to - start);
+}
+
+uint32_t
+ToLowerCase(nsACString& aStr)
+{
+  char* begin;
+  char* end;
+  uint32_t len = aStr.BeginWriting(&begin, &end);
+
+  for (; begin < end; ++begin) {
+    *begin = NS_ToLower(*begin);
+  }
+
+  return len;
+}
+
+uint32_t
+ToUpperCase(nsACString& aStr)
+{
+  char* begin;
+  char* end;
+  uint32_t len = aStr.BeginWriting(&begin, &end);
+
+  for (; begin < end; ++begin) {
+    *begin = NS_ToUpper(*begin);
+  }
+
+  return len;
+}
+
+uint32_t
+ToLowerCase(const nsACString& aSrc, nsACString& aDest)
+{
+  const char* begin;
+  const char* end;
+  uint32_t len = aSrc.BeginReading(&begin, &end);
+
+  char* dest;
+  NS_CStringGetMutableData(aDest, len, &dest);
+
+  for (; begin < end; ++begin, ++dest) {
+    *dest = NS_ToLower(*begin);
+  }
+
+  return len;
+}
+
+uint32_t
+ToUpperCase(const nsACString& aSrc, nsACString& aDest)
+{
+  const char* begin;
+  const char* end;
+  uint32_t len = aSrc.BeginReading(&begin, &end);
+
+  char* dest;
+  NS_CStringGetMutableData(aDest, len, &dest);
+
+  for (; begin < end; ++begin, ++dest) {
+    *dest = NS_ToUpper(*begin);
+  }
+
+  return len;
+}
+
+int32_t
+CaseInsensitiveCompare(const char* aStrA, const char* aStrB,
+                       uint32_t aLen)
+{
+  for (const char* aend = aStrA + aLen; aStrA < aend; ++aStrA, ++aStrB) {
+    char la = NS_ToLower(*aStrA);
+    char lb = NS_ToLower(*aStrB);
+
+    if (la == lb) {
+      continue;
+    }
+
+    return la < lb ? -1 : 1;
+  }
+
+  return 0;
+}
+
+bool
+ParseString(const nsACString& aSource, char aDelimiter,
+            nsTArray<nsCString>& aArray)
+{
+  int32_t start = 0;
+  int32_t end = aSource.Length();
+
+  uint32_t oldLength = aArray.Length();
+
+  for (;;) {
+    int32_t delimiter = aSource.FindChar(aDelimiter, start);
+    if (delimiter < 0) {
+      delimiter = end;
+    }
+
+    if (delimiter != start) {
+      if (!aArray.AppendElement(Substring(aSource, start, delimiter - start))) {
+        aArray.RemoveElementsAt(oldLength, aArray.Length() - oldLength);
+        return false;
+      }
+    }
+
+    if (delimiter == end) {
+      break;
+    }
+    start = ++delimiter;
+    if (start == end) {
+      break;
+    }
+  }
+
+  return true;
+}
diff --git a/xpcom/glue/nsStringAPI.h b/xpcom/glue/nsStringAPI.h
new file mode 100644
index 000000000..d5e368695
--- /dev/null
+++ b/xpcom/glue/nsStringAPI.h
@@ -0,0 +1,1596 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * This header provides wrapper classes around the frozen string API
+ * which are roughly equivalent to the internal string classes.
+ */
+
+#ifdef MOZILLA_INTERNAL_API
+#error nsStringAPI.h is only usable from non-MOZILLA_INTERNAL_API code!
+#endif
+
+#ifndef nsStringAPI_h__
+#define nsStringAPI_h__
+
+#include "mozilla/Attributes.h"
+#include "mozilla/Char16.h"
+
+#include "nsXPCOMStrings.h"
+#include "nsISupportsImpl.h"
+#include "mozilla/Logging.h"
+#include "nsTArray.h"
+
+/**
+ * Comparison function for use with nsACString::Equals
+ */
+NS_HIDDEN_(int32_t) CaseInsensitiveCompare(const char* aStrA, const char* aStrB,
+                                           uint32_t aLength);
+
+class nsAString
+{
+public:
+  typedef char16_t  char_type;
+  typedef nsAString self_type;
+  typedef uint32_t  size_type;
+  typedef uint32_t  index_type;
+
+  /**
+   * Returns the length, beginning, and end of a string in one operation.
+   */
+  NS_HIDDEN_(uint32_t) BeginReading(const char_type** aBegin,
+                                    const char_type** aEnd = nullptr) const;
+
+  NS_HIDDEN_(const char_type*) BeginReading() const;
+  NS_HIDDEN_(const char_type*) EndReading() const;
+
+  NS_HIDDEN_(char_type) CharAt(uint32_t aPos) const
+  {
+    NS_ASSERTION(aPos < Length(), "Out of bounds");
+    return BeginReading()[aPos];
+  }
+  NS_HIDDEN_(char_type) operator [](uint32_t aPos) const
+  {
+    return CharAt(aPos);
+  }
+  NS_HIDDEN_(char_type) First() const
+  {
+    return CharAt(0);
+  }
+  NS_HIDDEN_(char_type) Last() const
+  {
+    const char_type* data;
+    uint32_t dataLen = NS_StringGetData(*this, &data);
+    return data[dataLen - 1];
+  }
+
+  /**
+   * Get the length, begin writing, and optionally set the length of a
+   * string all in one operation.
+   *
+   * @param   newSize Size the string to this length. Pass UINT32_MAX
+   *                  to leave the length unchanged.
+   * @return  The new length of the string, or 0 if resizing failed.
+   */
+  NS_HIDDEN_(uint32_t) BeginWriting(char_type** aBegin,
+                                    char_type** aEnd = nullptr,
+                                    uint32_t aNewSize = UINT32_MAX);
+
+  NS_HIDDEN_(char_type*) BeginWriting(uint32_t = UINT32_MAX);
+  NS_HIDDEN_(char_type*) EndWriting();
+
+  NS_HIDDEN_(bool) SetLength(uint32_t aLen);
+
+  NS_HIDDEN_(size_type) Length() const
+  {
+    const char_type* data;
+    return NS_StringGetData(*this, &data);
+  }
+
+  NS_HIDDEN_(bool) IsEmpty() const { return Length() == 0; }
+
+  NS_HIDDEN_(void) SetIsVoid(bool aVal) { NS_StringSetIsVoid(*this, aVal); }
+  NS_HIDDEN_(bool) IsVoid() const { return NS_StringGetIsVoid(*this); }
+
+  NS_HIDDEN_(void) Assign(const self_type& aString)
+  {
+    NS_StringCopy(*this, aString);
+  }
+  NS_HIDDEN_(void) Assign(const char_type* aData, size_type aLength = UINT32_MAX)
+  {
+    NS_StringSetData(*this, aData, aLength);
+  }
+  NS_HIDDEN_(void) Assign(char_type aChar)
+  {
+    NS_StringSetData(*this, &aChar, 1);
+  }
+#ifdef MOZ_USE_CHAR16_WRAPPER
+  NS_HIDDEN_(void) Assign(char16ptr_t aData, size_type aLength = UINT32_MAX)
+  {
+    NS_StringSetData(*this, aData, aLength);
+  }
+#endif
+
+  NS_HIDDEN_(void) AssignLiteral(const char* aStr);
+  NS_HIDDEN_(void) AssignASCII(const char* aStr)
+  {
+    AssignLiteral(aStr);
+  }
+
+  NS_HIDDEN_(self_type&) operator=(const self_type& aString)
+  {
+    Assign(aString);
+    return *this;
+  }
+  NS_HIDDEN_(self_type&) operator=(const char_type* aPtr)
+  {
+    Assign(aPtr);
+    return *this;
+  }
+  NS_HIDDEN_(self_type&) operator=(char_type aChar)
+  {
+    Assign(aChar);
+    return *this;
+  }
+#ifdef MOZ_USE_CHAR16_WRAPPER
+  NS_HIDDEN_(self_type&) operator=(char16ptr_t aPtr)
+  {
+    Assign(aPtr);
+    return *this;
+  }
+#endif
+
+  NS_HIDDEN_(void) Replace(index_type aCutStart, size_type aCutLength,
+                           const char_type* aData,
+                           size_type aLength = size_type(-1))
+  {
+    NS_StringSetDataRange(*this, aCutStart, aCutLength, aData, aLength);
+  }
+  NS_HIDDEN_(void) Replace(index_type aCutStart, size_type aCutLength,
+                           char_type aChar)
+  {
+    Replace(aCutStart, aCutLength, &aChar, 1);
+  }
+  NS_HIDDEN_(void) Replace(index_type aCutStart, size_type aCutLength,
+                           const self_type& aReadable)
+  {
+    const char_type* data;
+    uint32_t dataLen = NS_StringGetData(aReadable, &data);
+    NS_StringSetDataRange(*this, aCutStart, aCutLength, data, dataLen);
+  }
+  NS_HIDDEN_(void) SetCharAt(char_type aChar, index_type aPos)
+  {
+    Replace(aPos, 1, &aChar, 1);
+  }
+
+  NS_HIDDEN_(void) Append(char_type aChar)
+  {
+    Replace(size_type(-1), 0, aChar);
+  }
+  NS_HIDDEN_(void) Append(const char_type* aData,
+                          size_type aLength = size_type(-1))
+  {
+    Replace(size_type(-1), 0, aData, aLength);
+  }
+#ifdef MOZ_USE_CHAR16_WRAPPER
+  NS_HIDDEN_(void) Append(char16ptr_t aData, size_type aLength = size_type(-1))
+  {
+    Append(static_cast<const char16_t*>(aData), aLength);
+  }
+#endif
+  NS_HIDDEN_(void) Append(const self_type& aReadable)
+  {
+    Replace(size_type(-1), 0, aReadable);
+  }
+  NS_HIDDEN_(void) AppendLiteral(const char* aASCIIStr);
+  NS_HIDDEN_(void) AppendASCII(const char* aASCIIStr)
+  {
+    AppendLiteral(aASCIIStr);
+  }
+
+  NS_HIDDEN_(self_type&) operator+=(char_type aChar)
+  {
+    Append(aChar);
+    return *this;
+  }
+  NS_HIDDEN_(self_type&) operator+=(const char_type* aData)
+  {
+    Append(aData);
+    return *this;
+  }
+  NS_HIDDEN_(self_type&) operator+=(const self_type& aReadable)
+  {
+    Append(aReadable);
+    return *this;
+  }
+
+  NS_HIDDEN_(void) Insert(char_type aChar, index_type aPos)
+  {
+    Replace(aPos, 0, aChar);
+  }
+  NS_HIDDEN_(void) Insert(const char_type* aData, index_type aPos,
+                          size_type aLength = size_type(-1))
+  {
+    Replace(aPos, 0, aData, aLength);
+  }
+  NS_HIDDEN_(void) Insert(const self_type& aReadable, index_type aPos)
+  {
+    Replace(aPos, 0, aReadable);
+  }
+
+  NS_HIDDEN_(void) Cut(index_type aCutStart, size_type aCutLength)
+  {
+    Replace(aCutStart, aCutLength, nullptr, 0);
+  }
+
+  NS_HIDDEN_(void) Truncate(size_type aNewLength = 0)
+  {
+    NS_ASSERTION(aNewLength <= Length(), "Truncate cannot make string longer");
+    SetLength(aNewLength);
+  }
+
+  /**
+   * Remove all occurences of characters in aSet from the string.
+   */
+  NS_HIDDEN_(void) StripChars(const char* aSet);
+
+  /**
+   * Strip whitespace characters from the string.
+   */
+  NS_HIDDEN_(void) StripWhitespace() { StripChars("\b\t\r\n "); }
+
+  NS_HIDDEN_(void) Trim(const char* aSet, bool aLeading = true,
+                        bool aTrailing = true);
+
+  /**
+   * Compare strings of characters. Return 0 if the characters are equal,
+   */
+  typedef int32_t (*ComparatorFunc)(const char_type* aStrA,
+                                    const char_type* aStrB,
+                                    uint32_t aLength);
+
+  static NS_HIDDEN_(int32_t) DefaultComparator(const char_type* aStrA,
+                                               const char_type* aStrB,
+                                               uint32_t aLength);
+
+  NS_HIDDEN_(int32_t) Compare(const char_type* aOther,
+                              ComparatorFunc aComparator = DefaultComparator) const;
+
+  NS_HIDDEN_(int32_t) Compare(const self_type& aOther,
+                              ComparatorFunc aComparator = DefaultComparator) const;
+
+  NS_HIDDEN_(bool) Equals(const char_type* aOther,
+                          ComparatorFunc aComparator = DefaultComparator) const;
+
+  NS_HIDDEN_(bool) Equals(const self_type& aOther,
+                          ComparatorFunc aComparator = DefaultComparator) const;
+
+  NS_HIDDEN_(bool) operator<(const self_type& aOther) const
+  {
+    return Compare(aOther) < 0;
+  }
+  NS_HIDDEN_(bool) operator<(const char_type* aOther) const
+  {
+    return Compare(aOther) < 0;
+  }
+
+  NS_HIDDEN_(bool) operator<=(const self_type& aOther) const
+  {
+    return Compare(aOther) <= 0;
+  }
+  NS_HIDDEN_(bool) operator<=(const char_type* aOther) const
+  {
+    return Compare(aOther) <= 0;
+  }
+
+  NS_HIDDEN_(bool) operator==(const self_type& aOther) const
+  {
+    return Equals(aOther);
+  }
+  NS_HIDDEN_(bool) operator==(const char_type* aOther) const
+  {
+    return Equals(aOther);
+  }
+#ifdef MOZ_USE_CHAR16_WRAPPER
+  NS_HIDDEN_(bool) operator==(char16ptr_t aOther) const
+  {
+    return Equals(aOther);
+  }
+#endif
+
+  NS_HIDDEN_(bool) operator>=(const self_type& aOther) const
+  {
+    return Compare(aOther) >= 0;
+  }
+  NS_HIDDEN_(bool) operator>=(const char_type* aOther) const
+  {
+    return Compare(aOther) >= 0;
+  }
+
+  NS_HIDDEN_(bool) operator>(const self_type& aOther) const
+  {
+    return Compare(aOther) > 0;
+  }
+  NS_HIDDEN_(bool) operator>(const char_type* aOther) const
+  {
+    return Compare(aOther) > 0;
+  }
+
+  NS_HIDDEN_(bool) operator!=(const self_type& aOther) const
+  {
+    return !Equals(aOther);
+  }
+  NS_HIDDEN_(bool) operator!=(const char_type* aOther) const
+  {
+    return !Equals(aOther);
+  }
+
+  NS_HIDDEN_(bool) EqualsLiteral(const char* aASCIIString) const;
+  NS_HIDDEN_(bool) EqualsASCII(const char* aASCIIString) const
+  {
+    return EqualsLiteral(aASCIIString);
+  }
+
+  /**
+   * Case-insensitive match this string to a lowercase ASCII string.
+   */
+  NS_HIDDEN_(bool) LowerCaseEqualsLiteral(const char* aASCIIString) const;
+
+  /**
+   * Find the first occurrence of aStr in this string.
+   *
+   * @return the offset of aStr, or -1 if not found
+   */
+  NS_HIDDEN_(int32_t) Find(const self_type& aStr,
+                           ComparatorFunc aComparator = DefaultComparator) const
+  {
+    return Find(aStr, 0, aComparator);
+  }
+
+  /**
+   * Find the first occurrence of aStr in this string, beginning at aOffset.
+   *
+   * @return the offset of aStr, or -1 if not found
+   */
+  NS_HIDDEN_(int32_t) Find(const self_type& aStr, uint32_t aOffset,
+                           ComparatorFunc aComparator = DefaultComparator) const;
+
+  /**
+   * Find an ASCII string within this string.
+   *
+   * @return the offset of aStr, or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) Find(const char* aStr, bool aIgnoreCase = false) const
+  {
+    return Find(aStr, 0, aIgnoreCase);
+  }
+
+  NS_HIDDEN_(int32_t) Find(const char* aStr, uint32_t aOffset,
+                           bool aIgnoreCase = false) const;
+
+  /**
+   * Find the last occurrence of aStr in this string.
+   *
+   * @return The offset of aStr from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFind(const self_type& aStr,
+                            ComparatorFunc aComparator = DefaultComparator) const
+  {
+    return RFind(aStr, -1, aComparator);
+  }
+
+  /**
+   * Find the last occurrence of aStr in this string, beginning at aOffset.
+   *
+   * @param aOffset the offset from the beginning of the string to begin
+   *        searching. If aOffset < 0, search from end of this string.
+   * @return The offset of aStr from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFind(const self_type& aStr, int32_t aOffset,
+                            ComparatorFunc aComparator = DefaultComparator) const;
+
+  /**
+   * Find the last occurrence of an ASCII string within this string.
+   *
+   * @return The offset of aStr from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFind(const char* aStr, bool aIgnoreCase = false) const
+  {
+    return RFind(aStr, -1, aIgnoreCase);
+  }
+
+  /**
+   * Find the last occurrence of an ASCII string beginning at aOffset.
+   *
+   * @param aOffset the offset from the beginning of the string to begin
+   *        searching. If aOffset < 0, search from end of this string.
+   * @return The offset of aStr from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFind(const char* aStr, int32_t aOffset,
+                            bool aIgnoreCase) const;
+
+  /**
+   * Search for the offset of the first occurrence of a character in a
+   * string.
+   *
+   * @param aOffset the offset from the beginning of the string to begin
+   *        searching
+   * @return The offset of the character from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) FindChar(char_type aChar, uint32_t aOffset = 0) const;
+
+  /**
+   * Search for the offset of the last occurrence of a character in a
+   * string.
+   *
+   * @return The offset of the character from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFindChar(char_type aChar) const;
+
+  /**
+   * Append a string representation of a number.
+   */
+  NS_HIDDEN_(void) AppendInt(int aInt, int32_t aRadix = 10);
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+  /**
+   * Convert this string to an integer.
+   *
+   * @param aErrorCode pointer to contain result code.
+   * @param aRadix must be 10 or 16
+   */
+  NS_HIDDEN_(int32_t) ToInteger(nsresult* aErrorCode,
+                                uint32_t aRadix = 10) const;
+  /**
+   * Convert this string to a 64-bit integer.
+   *
+   * @param aErrorCode pointer to contain result code.
+   * @param aRadix must be 10 or 16
+   */
+  NS_HIDDEN_(int64_t) ToInteger64(nsresult* aErrorCode,
+                                  uint32_t aRadix = 10) const;
+#endif // XPCOM_GLUE_AVOID_NSPR
+
+protected:
+  // Prevent people from allocating a nsAString directly.
+  ~nsAString() {}
+};
+
+class nsACString
+{
+public:
+  typedef char       char_type;
+  typedef nsACString self_type;
+  typedef uint32_t   size_type;
+  typedef uint32_t   index_type;
+
+  /**
+   * Returns the length, beginning, and end of a string in one operation.
+   */
+  NS_HIDDEN_(uint32_t) BeginReading(const char_type** aBegin,
+                                    const char_type** aEnd = nullptr) const;
+
+  NS_HIDDEN_(const char_type*) BeginReading() const;
+  NS_HIDDEN_(const char_type*) EndReading() const;
+
+  NS_HIDDEN_(char_type) CharAt(uint32_t aPos) const
+  {
+    NS_ASSERTION(aPos < Length(), "Out of bounds");
+    return BeginReading()[aPos];
+  }
+  NS_HIDDEN_(char_type) operator [](uint32_t aPos) const
+  {
+    return CharAt(aPos);
+  }
+  NS_HIDDEN_(char_type) First() const
+  {
+    return CharAt(0);
+  }
+  NS_HIDDEN_(char_type) Last() const
+  {
+    const char_type* data;
+    uint32_t dataLen = NS_CStringGetData(*this, &data);
+    return data[dataLen - 1];
+  }
+
+  /**
+   * Get the length, begin writing, and optionally set the length of a
+   * string all in one operation.
+   *
+   * @param   newSize Size the string to this length. Pass UINT32_MAX
+   *                  to leave the length unchanged.
+   * @return  The new length of the string, or 0 if resizing failed.
+   */
+  NS_HIDDEN_(uint32_t) BeginWriting(char_type** aBegin,
+                                    char_type** aEnd = nullptr,
+                                    uint32_t aNewSize = UINT32_MAX);
+
+  NS_HIDDEN_(char_type*) BeginWriting(uint32_t aLen = UINT32_MAX);
+  NS_HIDDEN_(char_type*) EndWriting();
+
+  NS_HIDDEN_(bool) SetLength(uint32_t aLen);
+
+  NS_HIDDEN_(size_type) Length() const
+  {
+    const char_type* data;
+    return NS_CStringGetData(*this, &data);
+  }
+
+  NS_HIDDEN_(bool) IsEmpty() const { return Length() == 0; }
+
+  NS_HIDDEN_(void) SetIsVoid(bool aVal) { NS_CStringSetIsVoid(*this, aVal); }
+  NS_HIDDEN_(bool) IsVoid() const { return NS_CStringGetIsVoid(*this); }
+
+  NS_HIDDEN_(void) Assign(const self_type& aString)
+  {
+    NS_CStringCopy(*this, aString);
+  }
+  NS_HIDDEN_(void) Assign(const char_type* aData, size_type aLength = UINT32_MAX)
+  {
+    NS_CStringSetData(*this, aData, aLength);
+  }
+  NS_HIDDEN_(void) Assign(char_type aChar)
+  {
+    NS_CStringSetData(*this, &aChar, 1);
+  }
+  NS_HIDDEN_(void) AssignLiteral(const char_type* aData)
+  {
+    Assign(aData);
+  }
+  NS_HIDDEN_(void) AssignASCII(const char_type* aData)
+  {
+    Assign(aData);
+  }
+
+  NS_HIDDEN_(self_type&) operator=(const self_type& aString)
+  {
+    Assign(aString);
+    return *this;
+  }
+  NS_HIDDEN_(self_type&) operator=(const char_type* aPtr)
+  {
+    Assign(aPtr);
+    return *this;
+  }
+  NS_HIDDEN_(self_type&) operator=(char_type aChar)
+  {
+    Assign(aChar);
+    return *this;
+  }
+
+  NS_HIDDEN_(void) Replace(index_type aCutStart, size_type aCutLength,
+                           const char_type* aData,
+                           size_type aLength = size_type(-1))
+  {
+    NS_CStringSetDataRange(*this, aCutStart, aCutLength, aData, aLength);
+  }
+  NS_HIDDEN_(void) Replace(index_type aCutStart, size_type aCutLength,
+                           char_type aChar)
+  {
+    Replace(aCutStart, aCutLength, &aChar, 1);
+  }
+  NS_HIDDEN_(void) Replace(index_type aCutStart, size_type aCutLength,
+                           const self_type& aReadable)
+  {
+    const char_type* data;
+    uint32_t dataLen = NS_CStringGetData(aReadable, &data);
+    NS_CStringSetDataRange(*this, aCutStart, aCutLength, data, dataLen);
+  }
+  NS_HIDDEN_(void) SetCharAt(char_type aChar, index_type aPos)
+  {
+    Replace(aPos, 1, &aChar, 1);
+  }
+
+  NS_HIDDEN_(void) Append(char_type aChar)
+  {
+    Replace(size_type(-1), 0, aChar);
+  }
+  NS_HIDDEN_(void) Append(const char_type* aData,
+                          size_type aLength = size_type(-1))
+  {
+    Replace(size_type(-1), 0, aData, aLength);
+  }
+  NS_HIDDEN_(void) Append(const self_type& aReadable)
+  {
+    Replace(size_type(-1), 0, aReadable);
+  }
+  NS_HIDDEN_(void) AppendLiteral(const char* aASCIIStr)
+  {
+    Append(aASCIIStr);
+  }
+  NS_HIDDEN_(void) AppendASCII(const char* aASCIIStr)
+  {
+    Append(aASCIIStr);
+  }
+
+  NS_HIDDEN_(self_type&) operator+=(char_type aChar)
+  {
+    Append(aChar);
+    return *this;
+  }
+  NS_HIDDEN_(self_type&) operator+=(const char_type* aData)
+  {
+    Append(aData);
+    return *this;
+  }
+  NS_HIDDEN_(self_type&) operator+=(const self_type& aReadable)
+  {
+    Append(aReadable);
+    return *this;
+  }
+
+  NS_HIDDEN_(void) Insert(char_type aChar, index_type aPos)
+  {
+    Replace(aPos, 0, aChar);
+  }
+  NS_HIDDEN_(void) Insert(const char_type* aData, index_type aPos,
+                          size_type aLength = size_type(-1))
+  {
+    Replace(aPos, 0, aData, aLength);
+  }
+  NS_HIDDEN_(void) Insert(const self_type& aReadable, index_type aPos)
+  {
+    Replace(aPos, 0, aReadable);
+  }
+
+  NS_HIDDEN_(void) Cut(index_type aCutStart, size_type aCutLength)
+  {
+    Replace(aCutStart, aCutLength, nullptr, 0);
+  }
+
+  NS_HIDDEN_(void) Truncate(size_type aNewLength = 0)
+  {
+    NS_ASSERTION(aNewLength <= Length(), "Truncate cannot make string longer");
+    SetLength(aNewLength);
+  }
+
+  /**
+   * Remove all occurences of characters in aSet from the string.
+   */
+  NS_HIDDEN_(void) StripChars(const char* aSet);
+
+  /**
+   * Strip whitespace characters from the string.
+   */
+  NS_HIDDEN_(void) StripWhitespace() { StripChars("\b\t\r\n "); }
+
+  NS_HIDDEN_(void) Trim(const char* aSet, bool aLeading = true,
+                        bool aTrailing = true);
+
+  /**
+   * Compare strings of characters. Return 0 if the characters are equal,
+   */
+  typedef int32_t (*ComparatorFunc)(const char_type* a,
+                                    const char_type* b,
+                                    uint32_t length);
+
+  static NS_HIDDEN_(int32_t) DefaultComparator(const char_type* aStrA,
+                                               const char_type* aStrB,
+                                               uint32_t aLength);
+
+  NS_HIDDEN_(int32_t) Compare(const char_type* aOther,
+                              ComparatorFunc aComparator = DefaultComparator) const;
+
+  NS_HIDDEN_(int32_t) Compare(const self_type& aOther,
+                              ComparatorFunc aComparator = DefaultComparator) const;
+
+  NS_HIDDEN_(bool) Equals(const char_type* aOther,
+                          ComparatorFunc aComparator = DefaultComparator) const;
+
+  NS_HIDDEN_(bool) Equals(const self_type& aOther,
+                          ComparatorFunc aComparator = DefaultComparator) const;
+
+  NS_HIDDEN_(bool) operator<(const self_type& aOther) const
+  {
+    return Compare(aOther) < 0;
+  }
+  NS_HIDDEN_(bool) operator<(const char_type* aOther) const
+  {
+    return Compare(aOther) < 0;
+  }
+
+  NS_HIDDEN_(bool) operator<=(const self_type& aOther) const
+  {
+    return Compare(aOther) <= 0;
+  }
+  NS_HIDDEN_(bool) operator<=(const char_type* aOther) const
+  {
+    return Compare(aOther) <= 0;
+  }
+
+  NS_HIDDEN_(bool) operator==(const self_type& aOther) const
+  {
+    return Equals(aOther);
+  }
+  NS_HIDDEN_(bool) operator==(const char_type* aOther) const
+  {
+    return Equals(aOther);
+  }
+
+  NS_HIDDEN_(bool) operator>=(const self_type& aOther) const
+  {
+    return Compare(aOther) >= 0;
+  }
+  NS_HIDDEN_(bool) operator>=(const char_type* aOther) const
+  {
+    return Compare(aOther) >= 0;
+  }
+
+  NS_HIDDEN_(bool) operator>(const self_type& aOther) const
+  {
+    return Compare(aOther) > 0;
+  }
+  NS_HIDDEN_(bool) operator>(const char_type* aOther) const
+  {
+    return Compare(aOther) > 0;
+  }
+
+  NS_HIDDEN_(bool) operator!=(const self_type& aOther) const
+  {
+    return !Equals(aOther);
+  }
+  NS_HIDDEN_(bool) operator!=(const char_type* aOther) const
+  {
+    return !Equals(aOther);
+  }
+
+  NS_HIDDEN_(bool) EqualsLiteral(const char_type* aOther) const
+  {
+    return Equals(aOther);
+  }
+  NS_HIDDEN_(bool) EqualsASCII(const char_type* aOther) const
+  {
+    return Equals(aOther);
+  }
+
+  /**
+   * Case-insensitive match this string to a lowercase ASCII string.
+   */
+  NS_HIDDEN_(bool) LowerCaseEqualsLiteral(const char* aASCIIString) const
+  {
+    return Equals(aASCIIString, CaseInsensitiveCompare);
+  }
+
+  /**
+   * Find the first occurrence of aStr in this string.
+   *
+   * @return the offset of aStr, or -1 if not found
+   */
+  NS_HIDDEN_(int32_t) Find(const self_type& aStr,
+                           ComparatorFunc aComparator = DefaultComparator) const
+  {
+    return Find(aStr, 0, aComparator);
+  }
+
+  /**
+   * Find the first occurrence of aStr in this string, beginning at aOffset.
+   *
+   * @return the offset of aStr, or -1 if not found
+   */
+  NS_HIDDEN_(int32_t) Find(const self_type& aStr, uint32_t aOffset,
+                           ComparatorFunc aComparator = DefaultComparator) const;
+
+  /**
+   * Find the first occurrence of aStr in this string.
+   *
+   * @return the offset of aStr, or -1 if not found
+   */
+  NS_HIDDEN_(int32_t) Find(const char_type* aStr,
+                           ComparatorFunc aComparator = DefaultComparator) const;
+
+  NS_HIDDEN_(int32_t) Find(const char_type* aStr, uint32_t aLen,
+                           ComparatorFunc aComparator = DefaultComparator) const;
+
+  /**
+   * Find the last occurrence of aStr in this string.
+   *
+   * @return The offset of the character from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFind(const self_type& aStr,
+                            ComparatorFunc aComparator = DefaultComparator) const
+  {
+    return RFind(aStr, -1, aComparator);
+  }
+
+  /**
+   * Find the last occurrence of aStr in this string, beginning at aOffset.
+   *
+   * @param aOffset the offset from the beginning of the string to begin
+   *        searching. If aOffset < 0, search from end of this string.
+   * @return The offset of aStr from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFind(const self_type& aStr, int32_t aOffset,
+                            ComparatorFunc aComparator = DefaultComparator) const;
+
+  /**
+   * Find the last occurrence of aStr in this string.
+   *
+   * @return The offset of aStr from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFind(const char_type* aStr,
+                            ComparatorFunc aComparator = DefaultComparator) const;
+
+  /**
+   * Find the last occurrence of an ASCII string in this string,
+   * beginning at aOffset.
+   *
+   * @param aLen is the length of aStr
+   * @return The offset of aStr from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFind(const char_type* aStr, int32_t aLen,
+                            ComparatorFunc aComparator = DefaultComparator) const;
+
+  /**
+   * Search for the offset of the first occurrence of a character in a
+   * string.
+   *
+   * @param aOffset the offset from the beginning of the string to begin
+   *        searching
+   * @return The offset of the character from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) FindChar(char_type aChar, uint32_t aOffset = 0) const;
+
+  /**
+   * Search for the offset of the last occurrence of a character in a
+   * string.
+   *
+   * @return The offset of the character from the beginning of the string,
+   *         or -1 if not found.
+   */
+  NS_HIDDEN_(int32_t) RFindChar(char_type aChar) const;
+
+  /**
+   * Append a string representation of a number.
+   */
+  NS_HIDDEN_(void) AppendInt(int aInt, int32_t aRadix = 10);
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+  /**
+   * Convert this string to an integer.
+   *
+   * @param aErrorCode pointer to contain result code.
+   * @param aRadix must be 10 or 16
+   */
+  NS_HIDDEN_(int32_t) ToInteger(nsresult* aErrorCode,
+                                uint32_t aRadix = 10) const;
+  /**
+   * Convert this string to a 64-bit integer.
+   *
+   * @param aErrorCode pointer to contain result code.
+   * @param aRadix must be 10 or 16
+   */
+  NS_HIDDEN_(int64_t) ToInteger64(nsresult* aErrorCode,
+                                  uint32_t aRadix = 10) const;
+#endif // XPCOM_GLUE_AVOID_NSPR
+
+protected:
+  // Prevent people from allocating a nsAString directly.
+  ~nsACString() {}
+};
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Below we define nsStringContainer and nsCStringContainer.  These classes
+ * have unspecified structure.  In most cases, your code should use
+ * nsString/nsCString instead of these classes; if you prefer C-style
+ * programming, then look no further.
+ */
+
+class nsStringContainer
+  : public nsAString
+  , private nsStringContainer_base
+{
+};
+
+class nsCStringContainer
+  : public nsACString
+  , private nsStringContainer_base
+{
+};
+
+/**
+ * The following classes are C++ helper classes that make the frozen string
+ * API easier to use.
+ */
+
+/**
+ * Rename symbols to avoid conflicting with internal versions.
+ */
+#define nsString                       nsString_external
+#define nsCString                      nsCString_external
+#define nsDependentString              nsDependentString_external
+#define nsDependentCString             nsDependentCString_external
+#define NS_ConvertASCIItoUTF16         NS_ConvertASCIItoUTF16_external
+#define NS_ConvertUTF8toUTF16          NS_ConvertUTF8toUTF16_external
+#define NS_ConvertUTF16toUTF8          NS_ConvertUTF16toUTF8_external
+#define NS_LossyConvertUTF16toASCII    NS_LossyConvertUTF16toASCII_external
+#define nsGetterCopies                 nsGetterCopies_external
+#define nsCGetterCopies                nsCGetterCopies_external
+#define nsDependentSubstring           nsDependentSubstring_external
+#define nsDependentCSubstring          nsDependentCSubstring_external
+
+/**
+ * basic strings
+ */
+
+class nsString : public nsStringContainer
+{
+public:
+  typedef nsString         self_type;
+  typedef nsAString        abstract_string_type;
+
+  nsString()
+  {
+    NS_StringContainerInit(*this);
+  }
+
+  nsString(const self_type& aString)
+  {
+    NS_StringContainerInit(*this);
+    NS_StringCopy(*this, aString);
+  }
+
+  explicit nsString(const abstract_string_type& aReadable)
+  {
+    NS_StringContainerInit(*this);
+    NS_StringCopy(*this, aReadable);
+  }
+
+  explicit nsString(const char_type* aData, size_type aLength = UINT32_MAX)
+  {
+    NS_StringContainerInit2(*this, aData, aLength, 0);
+  }
+
+#ifdef MOZ_USE_CHAR16_WRAPPER
+  explicit nsString(char16ptr_t aData, size_type aLength = UINT32_MAX)
+    : nsString(static_cast<const char16_t*>(aData), aLength)
+  {
+  }
+#endif
+
+  ~nsString()
+  {
+    NS_StringContainerFinish(*this);
+  }
+
+  char16ptr_t get() const
+  {
+    return char16ptr_t(BeginReading());
+  }
+
+  self_type& operator=(const self_type& aString)
+  {
+    Assign(aString);
+    return *this;
+  }
+  self_type& operator=(const abstract_string_type& aReadable)
+  {
+    Assign(aReadable);
+    return *this;
+  }
+  self_type& operator=(const char_type* aPtr)
+  {
+    Assign(aPtr);
+    return *this;
+  }
+  self_type& operator=(char_type aChar)
+  {
+    Assign(aChar);
+    return *this;
+  }
+
+  void Adopt(const char_type* aData, size_type aLength = UINT32_MAX)
+  {
+    NS_StringContainerFinish(*this);
+    NS_StringContainerInit2(*this, aData, aLength,
+                            NS_STRING_CONTAINER_INIT_ADOPT);
+  }
+
+protected:
+  nsString(const char_type* aData, size_type aLength, uint32_t aFlags)
+  {
+    NS_StringContainerInit2(*this, aData, aLength, aFlags);
+  }
+};
+
+class nsCString : public nsCStringContainer
+{
+public:
+  typedef nsCString        self_type;
+  typedef nsACString       abstract_string_type;
+
+  nsCString()
+  {
+    NS_CStringContainerInit(*this);
+  }
+
+  nsCString(const self_type& aString)
+  {
+    NS_CStringContainerInit(*this);
+    NS_CStringCopy(*this, aString);
+  }
+
+  explicit nsCString(const abstract_string_type& aReadable)
+  {
+    NS_CStringContainerInit(*this);
+    NS_CStringCopy(*this, aReadable);
+  }
+
+  explicit nsCString(const char_type* aData, size_type aLength = UINT32_MAX)
+  {
+    NS_CStringContainerInit(*this);
+    NS_CStringSetData(*this, aData, aLength);
+  }
+
+  ~nsCString()
+  {
+    NS_CStringContainerFinish(*this);
+  }
+
+  const char_type* get() const
+  {
+    return BeginReading();
+  }
+
+  self_type& operator=(const self_type& aString)
+  {
+    Assign(aString);
+    return *this;
+  }
+  self_type& operator=(const abstract_string_type& aReadable)
+  {
+    Assign(aReadable);
+    return *this;
+  }
+  self_type& operator=(const char_type* aPtr)
+  {
+    Assign(aPtr);
+    return *this;
+  }
+  self_type& operator=(char_type aChar)
+  {
+    Assign(aChar);
+    return *this;
+  }
+
+  void Adopt(const char_type* aData, size_type aLength = UINT32_MAX)
+  {
+    NS_CStringContainerFinish(*this);
+    NS_CStringContainerInit2(*this, aData, aLength,
+                             NS_CSTRING_CONTAINER_INIT_ADOPT);
+  }
+
+protected:
+  nsCString(const char_type* aData, size_type aLength, uint32_t aFlags)
+  {
+    NS_CStringContainerInit2(*this, aData, aLength, aFlags);
+  }
+};
+
+
+/**
+ * dependent strings
+ */
+
+class nsDependentString : public nsString
+{
+public:
+  typedef nsDependentString         self_type;
+
+  nsDependentString() {}
+
+  explicit nsDependentString(const char_type* aData,
+                             size_type aLength = UINT32_MAX)
+    : nsString(aData, aLength, NS_CSTRING_CONTAINER_INIT_DEPEND)
+  {
+  }
+
+#ifdef MOZ_USE_CHAR16_WRAPPER
+  explicit nsDependentString(char16ptr_t aData, size_type aLength = UINT32_MAX)
+    : nsDependentString(static_cast<const char16_t*>(aData), aLength)
+  {
+  }
+#endif
+
+  void Rebind(const char_type* aData, size_type aLength = UINT32_MAX)
+  {
+    NS_StringContainerFinish(*this);
+    NS_StringContainerInit2(*this, aData, aLength,
+                            NS_STRING_CONTAINER_INIT_DEPEND);
+  }
+
+private:
+  self_type& operator=(const self_type& aString) = delete;
+};
+
+class nsDependentCString : public nsCString
+{
+public:
+  typedef nsDependentCString        self_type;
+
+  nsDependentCString() {}
+
+  explicit nsDependentCString(const char_type* aData,
+                              size_type aLength = UINT32_MAX)
+    : nsCString(aData, aLength, NS_CSTRING_CONTAINER_INIT_DEPEND)
+  {
+  }
+
+  void Rebind(const char_type* aData, size_type aLength = UINT32_MAX)
+  {
+    NS_CStringContainerFinish(*this);
+    NS_CStringContainerInit2(*this, aData, aLength,
+                             NS_CSTRING_CONTAINER_INIT_DEPEND);
+  }
+
+private:
+  self_type& operator=(const self_type& aString) = delete;
+};
+
+
+/**
+ * conversion classes
+ */
+
+inline void
+CopyUTF16toUTF8(const nsAString& aSource, nsACString& aDest)
+{
+  NS_UTF16ToCString(aSource, NS_CSTRING_ENCODING_UTF8, aDest);
+}
+
+inline void
+CopyUTF8toUTF16(const nsACString& aSource, nsAString& aDest)
+{
+  NS_CStringToUTF16(aSource, NS_CSTRING_ENCODING_UTF8, aDest);
+}
+
+inline void
+LossyCopyUTF16toASCII(const nsAString& aSource, nsACString& aDest)
+{
+  NS_UTF16ToCString(aSource, NS_CSTRING_ENCODING_ASCII, aDest);
+}
+
+inline void
+CopyASCIItoUTF16(const nsACString& aSource, nsAString& aDest)
+{
+  NS_CStringToUTF16(aSource, NS_CSTRING_ENCODING_ASCII, aDest);
+}
+
+char*
+ToNewUTF8String(const nsAString& aSource);
+
+class NS_ConvertASCIItoUTF16 : public nsString
+{
+public:
+  typedef NS_ConvertASCIItoUTF16    self_type;
+
+  explicit NS_ConvertASCIItoUTF16(const nsACString& aStr)
+  {
+    NS_CStringToUTF16(aStr, NS_CSTRING_ENCODING_ASCII, *this);
+  }
+
+  explicit NS_ConvertASCIItoUTF16(const char* aData,
+                                  uint32_t aLength = UINT32_MAX)
+  {
+    NS_CStringToUTF16(nsDependentCString(aData, aLength),
+                      NS_CSTRING_ENCODING_ASCII, *this);
+  }
+
+private:
+  self_type& operator=(const self_type& aString) = delete;
+};
+
+class NS_ConvertUTF8toUTF16 : public nsString
+{
+public:
+  typedef NS_ConvertUTF8toUTF16    self_type;
+
+  explicit NS_ConvertUTF8toUTF16(const nsACString& aStr)
+  {
+    NS_CStringToUTF16(aStr, NS_CSTRING_ENCODING_UTF8, *this);
+  }
+
+  explicit NS_ConvertUTF8toUTF16(const char* aData,
+                                 uint32_t aLength = UINT32_MAX)
+  {
+    NS_CStringToUTF16(nsDependentCString(aData, aLength),
+                      NS_CSTRING_ENCODING_UTF8, *this);
+  }
+
+private:
+  self_type& operator=(const self_type& aString) = delete;
+};
+
+class NS_ConvertUTF16toUTF8 : public nsCString
+{
+public:
+  typedef NS_ConvertUTF16toUTF8    self_type;
+
+  explicit NS_ConvertUTF16toUTF8(const nsAString& aStr)
+  {
+    NS_UTF16ToCString(aStr, NS_CSTRING_ENCODING_UTF8, *this);
+  }
+
+  explicit NS_ConvertUTF16toUTF8(const char16ptr_t aData,
+                                 uint32_t aLength = UINT32_MAX)
+  {
+    NS_UTF16ToCString(nsDependentString(aData, aLength),
+                      NS_CSTRING_ENCODING_UTF8, *this);
+  }
+
+private:
+  self_type& operator=(const self_type& aString) = delete;
+};
+
+class NS_LossyConvertUTF16toASCII : public nsCString
+{
+public:
+  typedef NS_LossyConvertUTF16toASCII    self_type;
+
+  explicit NS_LossyConvertUTF16toASCII(const nsAString& aStr)
+  {
+    NS_UTF16ToCString(aStr, NS_CSTRING_ENCODING_ASCII, *this);
+  }
+
+  explicit NS_LossyConvertUTF16toASCII(const char16ptr_t aData,
+                                       uint32_t aLength = UINT32_MAX)
+  {
+    NS_UTF16ToCString(nsDependentString(aData, aLength),
+                      NS_CSTRING_ENCODING_ASCII, *this);
+  }
+
+private:
+  self_type& operator=(const self_type& aString) = delete;
+};
+
+
+/**
+ * literal strings
+ */
+static_assert(sizeof(char16_t) == 2, "size of char16_t must be 2");
+static_assert(char16_t(-1) > char16_t(0), "char16_t must be unsigned");
+
+#define NS_MULTILINE_LITERAL_STRING(s) \
+  nsDependentString(reinterpret_cast<const nsAString::char_type*>(s), \
+                    uint32_t((sizeof(s) / 2) - 1))
+#define NS_MULTILINE_LITERAL_STRING_INIT(n, s) \
+  n(reinterpret_cast<const nsAString::char_type*>(s), \
+    uint32_t((sizeof(s) / 2) - 1))
+#define NS_NAMED_MULTILINE_LITERAL_STRING(n,s) \
+  const nsDependentString n(reinterpret_cast<const nsAString::char_type*>(s), \
+                            uint32_t((sizeof(s) / 2) - 1))
+typedef nsDependentString nsLiteralString;
+
+#define NS_LITERAL_STRING(s) \
+  static_cast<const nsString&>(NS_MULTILINE_LITERAL_STRING(u"" s))
+#define NS_LITERAL_STRING_INIT(n, s) \
+  NS_MULTILINE_LITERAL_STRING_INIT(n, (u"" s))
+#define NS_NAMED_LITERAL_STRING(n, s) \
+  NS_NAMED_MULTILINE_LITERAL_STRING(n, (u"" s))
+
+#define NS_LITERAL_CSTRING(s) \
+  static_cast<const nsDependentCString&>(nsDependentCString(s, uint32_t(sizeof(s) - 1)))
+#define NS_LITERAL_CSTRING_INIT(n, s) \
+  n(s, uint32_t(sizeof(s)-1))
+#define NS_NAMED_LITERAL_CSTRING(n, s) \
+  const nsDependentCString n(s, uint32_t(sizeof(s)-1))
+
+typedef nsDependentCString nsLiteralCString;
+
+
+/**
+ * getter_Copies support
+ *
+ *    NS_IMETHOD GetBlah(char16_t**);
+ *
+ *    void some_function()
+ *    {
+ *      nsString blah;
+ *      GetBlah(getter_Copies(blah));
+ *      // ...
+ *    }
+ */
+
+class nsGetterCopies
+{
+public:
+  typedef char16_t char_type;
+
+  explicit nsGetterCopies(nsString& aStr)
+    : mString(aStr)
+    , mData(nullptr)
+  {
+  }
+
+  ~nsGetterCopies() { mString.Adopt(mData); }
+
+  operator char_type**() { return &mData; }
+
+private:
+  nsString&  mString;
+  char_type* mData;
+};
+
+inline nsGetterCopies
+getter_Copies(nsString& aString)
+{
+  return nsGetterCopies(aString);
+}
+
+class nsCGetterCopies
+{
+public:
+  typedef char char_type;
+
+  explicit nsCGetterCopies(nsCString& aStr)
+    : mString(aStr)
+    , mData(nullptr)
+  {
+  }
+
+  ~nsCGetterCopies() { mString.Adopt(mData); }
+
+  operator char_type**() { return &mData; }
+
+private:
+  nsCString& mString;
+  char_type* mData;
+};
+
+inline nsCGetterCopies
+getter_Copies(nsCString& aString)
+{
+  return nsCGetterCopies(aString);
+}
+
+
+/**
+* substrings
+*/
+
+class nsDependentSubstring : public nsStringContainer
+{
+public:
+  typedef nsDependentSubstring self_type;
+  typedef nsAString            abstract_string_type;
+
+  ~nsDependentSubstring() { NS_StringContainerFinish(*this); }
+  nsDependentSubstring() { NS_StringContainerInit(*this); }
+
+  nsDependentSubstring(const char_type* aStart, uint32_t aLength)
+  {
+    NS_StringContainerInit2(*this, aStart, aLength,
+                            NS_STRING_CONTAINER_INIT_DEPEND |
+                            NS_STRING_CONTAINER_INIT_SUBSTRING);
+  }
+
+  nsDependentSubstring(const abstract_string_type& aStr,
+                       uint32_t aStartPos);
+  nsDependentSubstring(const abstract_string_type& aStr,
+                       uint32_t aStartPos, uint32_t aLength);
+
+  void Rebind(const char_type* aStart, uint32_t aLength)
+  {
+    NS_StringContainerFinish(*this);
+    NS_StringContainerInit2(*this, aStart, aLength,
+                            NS_STRING_CONTAINER_INIT_DEPEND |
+                            NS_STRING_CONTAINER_INIT_SUBSTRING);
+  }
+
+private:
+  self_type& operator=(const self_type& aString) = delete;
+};
+
+class nsDependentCSubstring : public nsCStringContainer
+{
+public:
+  typedef nsDependentCSubstring self_type;
+  typedef nsACString            abstract_string_type;
+
+  ~nsDependentCSubstring() { NS_CStringContainerFinish(*this); }
+  nsDependentCSubstring() { NS_CStringContainerInit(*this); }
+
+  nsDependentCSubstring(const char_type* aStart, uint32_t aLength)
+  {
+    NS_CStringContainerInit2(*this, aStart, aLength,
+                             NS_CSTRING_CONTAINER_INIT_DEPEND |
+                             NS_CSTRING_CONTAINER_INIT_SUBSTRING);
+  }
+
+  nsDependentCSubstring(const abstract_string_type& aStr,
+                        uint32_t aStartPos);
+  nsDependentCSubstring(const abstract_string_type& aStr,
+                        uint32_t aStartPos, uint32_t aLength);
+
+  void Rebind(const char_type* aStart, uint32_t aLength)
+  {
+    NS_CStringContainerFinish(*this);
+    NS_CStringContainerInit2(*this, aStart, aLength,
+                             NS_CSTRING_CONTAINER_INIT_DEPEND |
+                             NS_CSTRING_CONTAINER_INIT_SUBSTRING);
+  }
+
+private:
+  self_type& operator=(const self_type& aString) = delete;
+};
+
+
+/**
+ * Various nsDependentC?Substring constructor functions
+ */
+
+// char16_t
+inline const nsDependentSubstring
+Substring(const nsAString& aStr, uint32_t aStartPos)
+{
+  return nsDependentSubstring(aStr, aStartPos);
+}
+
+inline const nsDependentSubstring
+Substring(const nsAString& aStr, uint32_t aStartPos, uint32_t aLength)
+{
+  return nsDependentSubstring(aStr, aStartPos, aLength);
+}
+
+inline const nsDependentSubstring
+Substring(const char16_t* aStart, const char16_t* aEnd)
+{
+  MOZ_ASSERT(uint32_t(aEnd - aStart) == uintptr_t(aEnd - aStart),
+             "string too long");
+  return nsDependentSubstring(aStart, uint32_t(aEnd - aStart));
+}
+
+inline const nsDependentSubstring
+Substring(const char16_t* aStart, uint32_t aLength)
+{
+  return nsDependentSubstring(aStart, aLength);
+}
+
+inline const nsDependentSubstring
+StringHead(const nsAString& aStr, uint32_t aCount)
+{
+  return nsDependentSubstring(aStr, 0, aCount);
+}
+
+inline const nsDependentSubstring
+StringTail(const nsAString& aStr, uint32_t aCount)
+{
+  return nsDependentSubstring(aStr, aStr.Length() - aCount, aCount);
+}
+
+// char
+inline const nsDependentCSubstring
+Substring(const nsACString& aStr, uint32_t aStartPos)
+{
+  return nsDependentCSubstring(aStr, aStartPos);
+}
+
+inline const nsDependentCSubstring
+Substring(const nsACString& aStr, uint32_t aStartPos, uint32_t aLength)
+{
+  return nsDependentCSubstring(aStr, aStartPos, aLength);
+}
+
+inline const nsDependentCSubstring
+Substring(const char* aStart, const char* aEnd)
+{
+  MOZ_ASSERT(uint32_t(aEnd - aStart) == uintptr_t(aEnd - aStart),
+             "string too long");
+  return nsDependentCSubstring(aStart, uint32_t(aEnd - aStart));
+}
+
+inline const nsDependentCSubstring
+Substring(const char* aStart, uint32_t aLength)
+{
+  return nsDependentCSubstring(aStart, aLength);
+}
+
+inline const nsDependentCSubstring
+StringHead(const nsACString& aStr, uint32_t aCount)
+{
+  return nsDependentCSubstring(aStr, 0, aCount);
+}
+
+inline const nsDependentCSubstring
+StringTail(const nsACString& aStr, uint32_t aCount)
+{
+  return nsDependentCSubstring(aStr, aStr.Length() - aCount, aCount);
+}
+
+
+inline bool
+StringBeginsWith(const nsAString& aSource, const nsAString& aSubstring,
+                 nsAString::ComparatorFunc aComparator = nsAString::DefaultComparator)
+{
+  return aSubstring.Length() <= aSource.Length() &&
+    StringHead(aSource, aSubstring.Length()).Equals(aSubstring, aComparator);
+}
+
+inline bool
+StringEndsWith(const nsAString& aSource, const nsAString& aSubstring,
+               nsAString::ComparatorFunc aComparator = nsAString::DefaultComparator)
+{
+  return aSubstring.Length() <= aSource.Length() &&
+    StringTail(aSource, aSubstring.Length()).Equals(aSubstring, aComparator);
+}
+
+inline bool
+StringBeginsWith(const nsACString& aSource, const nsACString& aSubstring,
+                 nsACString::ComparatorFunc aComparator = nsACString::DefaultComparator)
+{
+  return aSubstring.Length() <= aSource.Length() &&
+    StringHead(aSource, aSubstring.Length()).Equals(aSubstring, aComparator);
+}
+
+inline bool
+StringEndsWith(const nsACString& aSource, const nsACString& aSubstring,
+               nsACString::ComparatorFunc aComparator = nsACString::DefaultComparator)
+{
+  return aSubstring.Length() <= aSource.Length() &&
+    StringTail(aSource, aSubstring.Length()).Equals(aSubstring, aComparator);
+}
+
+/**
+ * Trim whitespace from the beginning and end of a string; then compress
+ * remaining runs of whitespace characters to a single space.
+ */
+NS_HIDDEN_(void) CompressWhitespace(nsAString& aString);
+
+#define EmptyCString() nsCString()
+#define EmptyString() nsString()
+
+/**
+ * Convert an ASCII string to all upper/lowercase (a-z,A-Z only). As a bonus,
+ * returns the string length.
+ */
+NS_HIDDEN_(uint32_t) ToLowerCase(nsACString& aStr);
+
+NS_HIDDEN_(uint32_t) ToUpperCase(nsACString& aStr);
+
+NS_HIDDEN_(uint32_t) ToLowerCase(const nsACString& aSrc, nsACString& aDest);
+
+NS_HIDDEN_(uint32_t) ToUpperCase(const nsACString& aSrc, nsACString& aDest);
+
+/**
+ * The following declarations are *deprecated*, and are included here only
+ * to make porting from existing code that doesn't use the frozen string API
+ * easier. They may disappear in the future.
+ */
+
+inline char*
+ToNewCString(const nsACString& aStr)
+{
+  return NS_CStringCloneData(aStr);
+}
+
+inline char16_t*
+ToNewUnicode(const nsAString& aStr)
+{
+  return NS_StringCloneData(aStr);
+}
+
+typedef nsString PromiseFlatString;
+typedef nsCString PromiseFlatCString;
+
+typedef nsCString nsAutoCString;
+typedef nsString nsAutoString;
+
+NS_HIDDEN_(bool) ParseString(const nsACString& aAstring, char aDelimiter,
+                             nsTArray<nsCString>& aArray);
+
+#endif // nsStringAPI_h__
diff --git a/xpcom/glue/nsStringGlue.h b/xpcom/glue/nsStringGlue.h
new file mode 100644
index 000000000..a444eb8a1
--- /dev/null
+++ b/xpcom/glue/nsStringGlue.h
@@ -0,0 +1,24 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+// IWYU pragma: private, include "nsString.h"
+
+/**
+ * @file nsStringGlue.h
+ * This header exists solely to #include the proper internal/frozen string
+ * headers, depending on whether MOZILLA_INTERNAL_API is defined.
+ */
+
+#ifndef nsStringGlue_h__
+#define nsStringGlue_h__
+
+#ifdef MOZILLA_INTERNAL_API
+#include "nsString.h"
+#include "nsReadableUtils.h"
+#else
+#include "nsStringAPI.h"
+#endif
+
+#endif // nsStringGlue_h__
diff --git a/xpcom/glue/nsTArray-inl.h b/xpcom/glue/nsTArray-inl.h
new file mode 100644
index 000000000..af57c9866
--- /dev/null
+++ b/xpcom/glue/nsTArray-inl.h
@@ -0,0 +1,463 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTArray_h__
+#  error "Don't include this file directly"
+#endif
+
+template<class Alloc, class Copy>
+nsTArray_base<Alloc, Copy>::nsTArray_base()
+  : mHdr(EmptyHdr())
+{
+  MOZ_COUNT_CTOR(nsTArray_base);
+}
+
+template<class Alloc, class Copy>
+nsTArray_base<Alloc, Copy>::~nsTArray_base()
+{
+  if (mHdr != EmptyHdr() && !UsesAutoArrayBuffer()) {
+    Alloc::Free(mHdr);
+  }
+  MOZ_COUNT_DTOR(nsTArray_base);
+}
+
+template<class Alloc, class Copy>
+const nsTArrayHeader*
+nsTArray_base<Alloc, Copy>::GetAutoArrayBufferUnsafe(size_t aElemAlign) const
+{
+  // Assuming |this| points to an nsAutoArray, we want to get a pointer to
+  // mAutoBuf.  So just cast |this| to nsAutoArray* and read &mAutoBuf!
+
+  const void* autoBuf =
+    &reinterpret_cast<const AutoTArray<nsTArray<uint32_t>, 1>*>(this)->mAutoBuf;
+
+  // If we're on a 32-bit system and aElemAlign is 8, we need to adjust our
+  // pointer to take into account the extra alignment in the auto array.
+
+  static_assert(sizeof(void*) != 4 ||
+                (MOZ_ALIGNOF(mozilla::AlignedElem<8>) == 8 &&
+                 sizeof(AutoTArray<mozilla::AlignedElem<8>, 1>) ==
+                   sizeof(void*) + sizeof(nsTArrayHeader) +
+                   4 + sizeof(mozilla::AlignedElem<8>)),
+                "auto array padding wasn't what we expected");
+
+  // We don't support alignments greater than 8 bytes.
+  MOZ_ASSERT(aElemAlign <= 4 || aElemAlign == 8,
+             "unsupported alignment.");
+  if (sizeof(void*) == 4 && aElemAlign == 8) {
+    autoBuf = reinterpret_cast<const char*>(autoBuf) + 4;
+  }
+
+  return reinterpret_cast<const Header*>(autoBuf);
+}
+
+template<class Alloc, class Copy>
+bool
+nsTArray_base<Alloc, Copy>::UsesAutoArrayBuffer() const
+{
+  if (!mHdr->mIsAutoArray) {
+    return false;
+  }
+
+  // This is nuts.  If we were sane, we'd pass aElemAlign as a parameter to
+  // this function.  Unfortunately this function is called in nsTArray_base's
+  // destructor, at which point we don't know elem_type's alignment.
+  //
+  // We'll fall on our face and return true when we should say false if
+  //
+  //   * we're not using our auto buffer,
+  //   * aElemAlign == 4, and
+  //   * mHdr == GetAutoArrayBuffer(8).
+  //
+  // This could happen if |*this| lives on the heap and malloc allocated our
+  // buffer on the heap adjacent to |*this|.
+  //
+  // However, we can show that this can't happen.  If |this| is an auto array
+  // (as we ensured at the beginning of the method), GetAutoArrayBuffer(8)
+  // always points to memory owned by |*this|, because (as we assert below)
+  //
+  //   * GetAutoArrayBuffer(8) is at most 4 bytes past GetAutoArrayBuffer(4), and
+  //   * sizeof(nsTArrayHeader) > 4.
+  //
+  // Since AutoTArray always contains an nsTArrayHeader,
+  // GetAutoArrayBuffer(8) will always point inside the auto array object,
+  // even if it doesn't point at the beginning of the header.
+  //
+  // Note that this means that we can't store elements with alignment 16 in an
+  // nsTArray, because GetAutoArrayBuffer(16) could lie outside the memory
+  // owned by this AutoTArray.  We statically assert that elem_type's
+  // alignment is 8 bytes or less in AutoTArray.
+
+  static_assert(sizeof(nsTArrayHeader) > 4,
+                "see comment above");
+
+#ifdef DEBUG
+  ptrdiff_t diff = reinterpret_cast<const char*>(GetAutoArrayBuffer(8)) -
+                   reinterpret_cast<const char*>(GetAutoArrayBuffer(4));
+  MOZ_ASSERT(diff >= 0 && diff <= 4,
+             "GetAutoArrayBuffer doesn't do what we expect.");
+#endif
+
+  return mHdr == GetAutoArrayBuffer(4) || mHdr == GetAutoArrayBuffer(8);
+}
+
+// defined in nsTArray.cpp
+bool IsTwiceTheRequiredBytesRepresentableAsUint32(size_t aCapacity,
+                                                  size_t aElemSize);
+
+template<class Alloc, class Copy>
+template<typename ActualAlloc>
+typename ActualAlloc::ResultTypeProxy
+nsTArray_base<Alloc, Copy>::EnsureCapacity(size_type aCapacity,
+                                           size_type aElemSize)
+{
+  // This should be the most common case so test this first
+  if (aCapacity <= mHdr->mCapacity) {
+    return ActualAlloc::SuccessResult();
+  }
+
+  // If the requested memory allocation exceeds size_type(-1)/2, then
+  // our doubling algorithm may not be able to allocate it.
+  // Additionally, if it exceeds uint32_t(-1) then we couldn't fit in the
+  // Header::mCapacity member. Just bail out in cases like that.  We don't want
+  // to be allocating 2 GB+ arrays anyway.
+  if (!IsTwiceTheRequiredBytesRepresentableAsUint32(aCapacity, aElemSize)) {
+    ActualAlloc::SizeTooBig((size_t)aCapacity * aElemSize);
+    return ActualAlloc::FailureResult();
+  }
+
+  size_t reqSize = sizeof(Header) + aCapacity * aElemSize;
+
+  if (mHdr == EmptyHdr()) {
+    // Malloc() new data
+    Header* header = static_cast<Header*>(ActualAlloc::Malloc(reqSize));
+    if (!header) {
+      return ActualAlloc::FailureResult();
+    }
+    header->mLength = 0;
+    header->mCapacity = aCapacity;
+    header->mIsAutoArray = 0;
+    mHdr = header;
+
+    return ActualAlloc::SuccessResult();
+  }
+
+  // We increase our capacity so that the allocated buffer grows exponentially,
+  // which gives us amortized O(1) appending. Below the threshold, we use
+  // powers-of-two. Above the threshold, we grow by at least 1.125, rounding up
+  // to the nearest MiB.
+  const size_t slowGrowthThreshold = 8 * 1024 * 1024;
+
+  size_t bytesToAlloc;
+  if (reqSize >= slowGrowthThreshold) {
+    size_t currSize = sizeof(Header) + Capacity() * aElemSize;
+    size_t minNewSize = currSize + (currSize >> 3); // multiply by 1.125
+    bytesToAlloc = reqSize > minNewSize ? reqSize : minNewSize;
+
+    // Round up to the next multiple of MiB.
+    const size_t MiB = 1 << 20;
+    bytesToAlloc = MiB * ((bytesToAlloc + MiB - 1) / MiB);
+  } else {
+    // Round up to the next power of two.
+    bytesToAlloc = mozilla::RoundUpPow2(reqSize);
+  }
+
+  Header* header;
+  if (UsesAutoArrayBuffer() || !Copy::allowRealloc) {
+    // Malloc() and copy
+    header = static_cast<Header*>(ActualAlloc::Malloc(bytesToAlloc));
+    if (!header) {
+      return ActualAlloc::FailureResult();
+    }
+
+    Copy::MoveNonOverlappingRegionWithHeader(header, mHdr, Length(), aElemSize);
+
+    if (!UsesAutoArrayBuffer()) {
+      ActualAlloc::Free(mHdr);
+    }
+  } else {
+    // Realloc() existing data
+    header = static_cast<Header*>(ActualAlloc::Realloc(mHdr, bytesToAlloc));
+    if (!header) {
+      return ActualAlloc::FailureResult();
+    }
+  }
+
+  // How many elements can we fit in bytesToAlloc?
+  size_t newCapacity = (bytesToAlloc - sizeof(Header)) / aElemSize;
+  MOZ_ASSERT(newCapacity >= aCapacity, "Didn't enlarge the array enough!");
+  header->mCapacity = newCapacity;
+
+  mHdr = header;
+
+  return ActualAlloc::SuccessResult();
+}
+
+// We don't need use Alloc template parameter specified here because failure to
+// shrink the capacity will leave the array unchanged.
+template<class Alloc, class Copy>
+void
+nsTArray_base<Alloc, Copy>::ShrinkCapacity(size_type aElemSize,
+                                           size_t aElemAlign)
+{
+  if (mHdr == EmptyHdr() || UsesAutoArrayBuffer()) {
+    return;
+  }
+
+  if (mHdr->mLength >= mHdr->mCapacity) { // should never be greater than...
+    return;
+  }
+
+  size_type length = Length();
+
+  if (IsAutoArray() && GetAutoArrayBuffer(aElemAlign)->mCapacity >= length) {
+    Header* header = GetAutoArrayBuffer(aElemAlign);
+
+    // Move the data, but don't copy the header to avoid overwriting mCapacity.
+    header->mLength = length;
+    Copy::MoveNonOverlappingRegion(header + 1, mHdr + 1, length, aElemSize);
+
+    nsTArrayFallibleAllocator::Free(mHdr);
+    mHdr = header;
+    return;
+  }
+
+  if (length == 0) {
+    MOZ_ASSERT(!IsAutoArray(), "autoarray should have fit 0 elements");
+    nsTArrayFallibleAllocator::Free(mHdr);
+    mHdr = EmptyHdr();
+    return;
+  }
+
+  size_type size = sizeof(Header) + length * aElemSize;
+  void* ptr = nsTArrayFallibleAllocator::Realloc(mHdr, size);
+  if (!ptr) {
+    return;
+  }
+  mHdr = static_cast<Header*>(ptr);
+  mHdr->mCapacity = length;
+}
+
+template<class Alloc, class Copy>
+template<typename ActualAlloc>
+void
+nsTArray_base<Alloc, Copy>::ShiftData(index_type aStart,
+                                      size_type aOldLen, size_type aNewLen,
+                                      size_type aElemSize, size_t aElemAlign)
+{
+  if (aOldLen == aNewLen) {
+    return;
+  }
+
+  // Determine how many elements need to be shifted
+  size_type num = mHdr->mLength - (aStart + aOldLen);
+
+  // Compute the resulting length of the array
+  mHdr->mLength += aNewLen - aOldLen;
+  if (mHdr->mLength == 0) {
+    ShrinkCapacity(aElemSize, aElemAlign);
+  } else {
+    // Maybe nothing needs to be shifted
+    if (num == 0) {
+      return;
+    }
+    // Perform shift (change units to bytes first)
+    aStart *= aElemSize;
+    aNewLen *= aElemSize;
+    aOldLen *= aElemSize;
+    char* baseAddr = reinterpret_cast<char*>(mHdr + 1) + aStart;
+    Copy::MoveOverlappingRegion(baseAddr + aNewLen, baseAddr + aOldLen, num, aElemSize);
+  }
+}
+
+template<class Alloc, class Copy>
+template<typename ActualAlloc>
+bool
+nsTArray_base<Alloc, Copy>::InsertSlotsAt(index_type aIndex, size_type aCount,
+                                          size_type aElemSize,
+                                          size_t aElemAlign)
+{
+  MOZ_ASSERT(aIndex <= Length(), "Bogus insertion index");
+  size_type newLen = Length() + aCount;
+
+  EnsureCapacity<ActualAlloc>(newLen, aElemSize);
+
+  // Check for out of memory conditions
+  if (Capacity() < newLen) {
+    return false;
+  }
+
+  // Move the existing elements as needed.  Note that this will
+  // change our mLength, so no need to call IncrementLength.
+  ShiftData<ActualAlloc>(aIndex, 0, aCount, aElemSize, aElemAlign);
+
+  return true;
+}
+
+// nsTArray_base::IsAutoArrayRestorer is an RAII class which takes
+// |nsTArray_base &array| in its constructor.  When it's destructed, it ensures
+// that
+//
+//   * array.mIsAutoArray has the same value as it did when we started, and
+//   * if array has an auto buffer and mHdr would otherwise point to sEmptyHdr,
+//     array.mHdr points to array's auto buffer.
+
+template<class Alloc, class Copy>
+nsTArray_base<Alloc, Copy>::IsAutoArrayRestorer::IsAutoArrayRestorer(
+      nsTArray_base<Alloc, Copy>& aArray,
+      size_t aElemAlign)
+  : mArray(aArray)
+  , mElemAlign(aElemAlign)
+  , mIsAuto(aArray.IsAutoArray())
+{
+}
+
+template<class Alloc, class Copy>
+nsTArray_base<Alloc, Copy>::IsAutoArrayRestorer::~IsAutoArrayRestorer()
+{
+  // Careful: We don't want to set mIsAutoArray = 1 on sEmptyHdr.
+  if (mIsAuto && mArray.mHdr == mArray.EmptyHdr()) {
+    // Call GetAutoArrayBufferUnsafe() because GetAutoArrayBuffer() asserts
+    // that mHdr->mIsAutoArray is true, which surely isn't the case here.
+    mArray.mHdr = mArray.GetAutoArrayBufferUnsafe(mElemAlign);
+    mArray.mHdr->mLength = 0;
+  } else if (mArray.mHdr != mArray.EmptyHdr()) {
+    mArray.mHdr->mIsAutoArray = mIsAuto;
+  }
+}
+
+template<class Alloc, class Copy>
+template<typename ActualAlloc, class Allocator>
+typename ActualAlloc::ResultTypeProxy
+nsTArray_base<Alloc, Copy>::SwapArrayElements(nsTArray_base<Allocator,
+                                                            Copy>& aOther,
+                                              size_type aElemSize,
+                                              size_t aElemAlign)
+{
+
+  // EnsureNotUsingAutoArrayBuffer will set mHdr = sEmptyHdr even if we have an
+  // auto buffer.  We need to point mHdr back to our auto buffer before we
+  // return, otherwise we'll forget that we have an auto buffer at all!
+  // IsAutoArrayRestorer takes care of this for us.
+
+  IsAutoArrayRestorer ourAutoRestorer(*this, aElemAlign);
+  typename nsTArray_base<Allocator, Copy>::IsAutoArrayRestorer
+    otherAutoRestorer(aOther, aElemAlign);
+
+  // If neither array uses an auto buffer which is big enough to store the
+  // other array's elements, then ensure that both arrays use malloc'ed storage
+  // and swap their mHdr pointers.
+  if ((!UsesAutoArrayBuffer() || Capacity() < aOther.Length()) &&
+      (!aOther.UsesAutoArrayBuffer() || aOther.Capacity() < Length())) {
+
+    if (!EnsureNotUsingAutoArrayBuffer<ActualAlloc>(aElemSize) ||
+        !aOther.template EnsureNotUsingAutoArrayBuffer<ActualAlloc>(aElemSize)) {
+      return ActualAlloc::FailureResult();
+    }
+
+    Header* temp = mHdr;
+    mHdr = aOther.mHdr;
+    aOther.mHdr = temp;
+
+    return ActualAlloc::SuccessResult();
+  }
+
+  // Swap the two arrays by copying, since at least one is using an auto
+  // buffer which is large enough to hold all of the aOther's elements.  We'll
+  // copy the shorter array into temporary storage.
+  //
+  // (We could do better than this in some circumstances.  Suppose we're
+  // swapping arrays X and Y.  X has space for 2 elements in its auto buffer,
+  // but currently has length 4, so it's using malloc'ed storage.  Y has length
+  // 2.  When we swap X and Y, we don't need to use a temporary buffer; we can
+  // write Y straight into X's auto buffer, write X's malloc'ed buffer on top
+  // of Y, and then switch X to using its auto buffer.)
+
+  if (!ActualAlloc::Successful(EnsureCapacity<ActualAlloc>(aOther.Length(), aElemSize)) ||
+      !Allocator::Successful(aOther.template EnsureCapacity<Allocator>(Length(), aElemSize))) {
+    return ActualAlloc::FailureResult();
+  }
+
+  // The EnsureCapacity calls above shouldn't have caused *both* arrays to
+  // switch from their auto buffers to malloc'ed space.
+  MOZ_ASSERT(UsesAutoArrayBuffer() || aOther.UsesAutoArrayBuffer(),
+             "One of the arrays should be using its auto buffer.");
+
+  size_type smallerLength = XPCOM_MIN(Length(), aOther.Length());
+  size_type largerLength = XPCOM_MAX(Length(), aOther.Length());
+  void* smallerElements;
+  void* largerElements;
+  if (Length() <= aOther.Length()) {
+    smallerElements = Hdr() + 1;
+    largerElements = aOther.Hdr() + 1;
+  } else {
+    smallerElements = aOther.Hdr() + 1;
+    largerElements = Hdr() + 1;
+  }
+
+  // Allocate temporary storage for the smaller of the two arrays.  We want to
+  // allocate this space on the stack, if it's not too large.  Sounds like a
+  // job for AutoTArray!  (One of the two arrays we're swapping is using an
+  // auto buffer, so we're likely not allocating a lot of space here.  But one
+  // could, in theory, allocate a huge AutoTArray on the heap.)
+  AutoTArray<nsTArray_Impl<uint8_t, ActualAlloc>, 64> temp;
+  if (!ActualAlloc::Successful(temp.template EnsureCapacity<ActualAlloc>(smallerLength,
+                                                                         aElemSize))) {
+    return ActualAlloc::FailureResult();
+  }
+
+  Copy::MoveNonOverlappingRegion(temp.Elements(), smallerElements, smallerLength, aElemSize);
+  Copy::MoveNonOverlappingRegion(smallerElements, largerElements, largerLength, aElemSize);
+  Copy::MoveNonOverlappingRegion(largerElements, temp.Elements(), smallerLength, aElemSize);
+
+  // Swap the arrays' lengths.
+  MOZ_ASSERT((aOther.Length() == 0 || mHdr != EmptyHdr()) &&
+             (Length() == 0 || aOther.mHdr != EmptyHdr()),
+             "Don't set sEmptyHdr's length.");
+  size_type tempLength = Length();
+
+  // Avoid writing to EmptyHdr, since it can trigger false
+  // positives with TSan.
+  if (mHdr != EmptyHdr()) {
+    mHdr->mLength = aOther.Length();
+  }
+  if (aOther.mHdr != EmptyHdr()) {
+    aOther.mHdr->mLength = tempLength;
+  }
+
+  return ActualAlloc::SuccessResult();
+}
+
+template<class Alloc, class Copy>
+template<typename ActualAlloc>
+bool
+nsTArray_base<Alloc, Copy>::EnsureNotUsingAutoArrayBuffer(size_type aElemSize)
+{
+  if (UsesAutoArrayBuffer()) {
+
+    // If you call this on a 0-length array, we'll set that array's mHdr to
+    // sEmptyHdr, in flagrant violation of the AutoTArray invariants.  It's
+    // up to you to set it back!  (If you don't, the AutoTArray will forget
+    // that it has an auto buffer.)
+    if (Length() == 0) {
+      mHdr = EmptyHdr();
+      return true;
+    }
+
+    size_type size = sizeof(Header) + Length() * aElemSize;
+
+    Header* header = static_cast<Header*>(ActualAlloc::Malloc(size));
+    if (!header) {
+      return false;
+    }
+
+    Copy::MoveNonOverlappingRegionWithHeader(header, mHdr, Length(), aElemSize);
+    header->mCapacity = Length();
+    mHdr = header;
+  }
+
+  return true;
+}
diff --git a/xpcom/glue/nsTArray.cpp b/xpcom/glue/nsTArray.cpp
new file mode 100644
index 000000000..fd8422ec7
--- /dev/null
+++ b/xpcom/glue/nsTArray.cpp
@@ -0,0 +1,29 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <string.h>
+#include "nsTArray.h"
+#include "nsXPCOM.h"
+#include "nsDebug.h"
+#include "mozilla/CheckedInt.h"
+#include "mozilla/IntegerPrintfMacros.h"
+
+nsTArrayHeader nsTArrayHeader::sEmptyHdr = { 0, 0, 0 };
+
+bool
+IsTwiceTheRequiredBytesRepresentableAsUint32(size_t aCapacity, size_t aElemSize)
+{
+  using mozilla::CheckedUint32;
+  return ((CheckedUint32(aCapacity) * aElemSize) * 2).isValid();
+}
+
+MOZ_NORETURN MOZ_COLD void
+InvalidArrayIndex_CRASH(size_t aIndex, size_t aLength)
+{
+  MOZ_CRASH_UNSAFE_PRINTF(
+    "ElementAt(aIndex = %" PRIu64 ", aLength = %" PRIu64 ")",
+    static_cast<uint64_t>(aIndex), static_cast<uint64_t>(aLength));
+}
diff --git a/xpcom/glue/nsTArray.h b/xpcom/glue/nsTArray.h
new file mode 100644
index 000000000..ca74a41f7
--- /dev/null
+++ b/xpcom/glue/nsTArray.h
@@ -0,0 +1,2371 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTArray_h__
+#define nsTArray_h__
+
+#include "nsTArrayForwardDeclare.h"
+#include "mozilla/Alignment.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/BinarySearch.h"
+#include "mozilla/fallible.h"
+#include "mozilla/Function.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Move.h"
+#include "mozilla/ReverseIterator.h"
+#include "mozilla/TypeTraits.h"
+
+#include <string.h>
+
+#include "nsCycleCollectionNoteChild.h"
+#include "nsAlgorithm.h"
+#include "nscore.h"
+#include "nsQuickSort.h"
+#include "nsDebug.h"
+#include "nsISupportsImpl.h"
+#include "nsRegionFwd.h"
+#include <initializer_list>
+#include <new>
+
+namespace JS {
+template<class T>
+class Heap;
+class ObjectPtr;
+} /* namespace JS */
+
+class nsRegion;
+namespace mozilla {
+namespace layers {
+struct TileClient;
+} // namespace layers
+} // namespace mozilla
+
+namespace mozilla {
+struct SerializedStructuredCloneBuffer;
+} // namespace mozilla
+
+namespace mozilla {
+namespace dom {
+namespace ipc {
+class StructuredCloneData;
+} // namespace ipc
+} // namespace dom
+} // namespace mozilla
+
+namespace mozilla {
+namespace dom {
+class ClonedMessageData;
+class MessagePortMessage;
+namespace indexedDB {
+struct StructuredCloneReadInfo;
+class SerializedStructuredCloneReadInfo;
+class ObjectStoreCursorResponse;
+} // namespace indexedDB
+} // namespace dom
+} // namespace mozilla
+
+class JSStructuredCloneData;
+
+//
+// nsTArray is a resizable array class, like std::vector.
+//
+// Unlike std::vector, which follows C++'s construction/destruction rules,
+// nsTArray assumes that your "T" can be memmoved()'ed safely.
+//
+// The public classes defined in this header are
+//
+//   nsTArray<T>,
+//   FallibleTArray<T>,
+//   AutoTArray<T, N>, and
+//
+// nsTArray and AutoTArray are infallible by default. To opt-in to fallible
+// behaviour, use the `mozilla::fallible` parameter and check the return value.
+//
+// If you just want to declare the nsTArray types (e.g., if you're in a header
+// file and don't need the full nsTArray definitions) consider including
+// nsTArrayForwardDeclare.h instead of nsTArray.h.
+//
+// The template parameter (i.e., T in nsTArray<T>) specifies the type of the
+// elements and has the following requirements:
+//
+//   T MUST be safely memmove()'able.
+//   T MUST define a copy-constructor.
+//   T MAY define operator< for sorting.
+//   T MAY define operator== for searching.
+//
+// (Note that the memmove requirement may be relaxed for certain types - see
+// nsTArray_CopyChooser below.)
+//
+// For methods taking a Comparator instance, the Comparator must be a class
+// defining the following methods:
+//
+//   class Comparator {
+//     public:
+//       /** @return True if the elements are equals; false otherwise. */
+//       bool Equals(const elem_type& a, const Item& b) const;
+//
+//       /** @return True if (a < b); false otherwise. */
+//       bool LessThan(const elem_type& a, const Item& b) const;
+//   };
+//
+// The Equals method is used for searching, and the LessThan method is used for
+// searching and sorting.  The |Item| type above can be arbitrary, but must
+// match the Item type passed to the sort or search function.
+//
+
+
+//
+// nsTArrayFallibleResult and nsTArrayInfallibleResult types are proxy types
+// which are used because you cannot use a templated type which is bound to
+// void as an argument to a void function.  In order to work around that, we
+// encode either a void or a boolean inside these proxy objects, and pass them
+// to the aforementioned function instead, and then use the type information to
+// decide what to do in the function.
+//
+// Note that public nsTArray methods should never return a proxy type.  Such
+// types are only meant to be used in the internal nsTArray helper methods.
+// Public methods returning non-proxy types cannot be called from other
+// nsTArray members.
+//
+struct nsTArrayFallibleResult
+{
+  // Note: allows implicit conversions from and to bool
+  MOZ_IMPLICIT nsTArrayFallibleResult(bool aResult) : mResult(aResult) {}
+
+  MOZ_IMPLICIT operator bool() { return mResult; }
+
+private:
+  bool mResult;
+};
+
+struct nsTArrayInfallibleResult
+{
+};
+
+//
+// nsTArray*Allocators must all use the same |free()|, to allow swap()'ing
+// between fallible and infallible variants.
+//
+
+struct nsTArrayFallibleAllocatorBase
+{
+  typedef bool ResultType;
+  typedef nsTArrayFallibleResult ResultTypeProxy;
+
+  static ResultType Result(ResultTypeProxy aResult) { return aResult; }
+  static bool Successful(ResultTypeProxy aResult) { return aResult; }
+  static ResultTypeProxy SuccessResult() { return true; }
+  static ResultTypeProxy FailureResult() { return false; }
+  static ResultType ConvertBoolToResultType(bool aValue) { return aValue; }
+};
+
+struct nsTArrayInfallibleAllocatorBase
+{
+  typedef void ResultType;
+  typedef nsTArrayInfallibleResult ResultTypeProxy;
+
+  static ResultType Result(ResultTypeProxy aResult) {}
+  static bool Successful(ResultTypeProxy) { return true; }
+  static ResultTypeProxy SuccessResult() { return ResultTypeProxy(); }
+
+  static ResultTypeProxy FailureResult()
+  {
+    NS_RUNTIMEABORT("Infallible nsTArray should never fail");
+    return ResultTypeProxy();
+  }
+
+  static ResultType ConvertBoolToResultType(bool aValue)
+  {
+    if (!aValue) {
+      NS_RUNTIMEABORT("infallible nsTArray should never convert false to ResultType");
+    }
+  }
+};
+
+struct nsTArrayFallibleAllocator : nsTArrayFallibleAllocatorBase
+{
+  static void* Malloc(size_t aSize) { return malloc(aSize); }
+  static void* Realloc(void* aPtr, size_t aSize)
+  {
+    return realloc(aPtr, aSize);
+  }
+
+  static void Free(void* aPtr) { free(aPtr); }
+  static void SizeTooBig(size_t) {}
+};
+
+#if defined(MOZALLOC_HAVE_XMALLOC)
+#include "mozilla/mozalloc_abort.h"
+
+struct nsTArrayInfallibleAllocator : nsTArrayInfallibleAllocatorBase
+{
+  static void* Malloc(size_t aSize) { return moz_xmalloc(aSize); }
+  static void* Realloc(void* aPtr, size_t aSize)
+  {
+    return moz_xrealloc(aPtr, aSize);
+  }
+
+  static void Free(void* aPtr) { free(aPtr); }
+  static void SizeTooBig(size_t aSize) { NS_ABORT_OOM(aSize); }
+};
+
+#else
+#include <stdlib.h>
+
+struct nsTArrayInfallibleAllocator : nsTArrayInfallibleAllocatorBase
+{
+  static void* Malloc(size_t aSize)
+  {
+    void* ptr = malloc(aSize);
+    if (MOZ_UNLIKELY(!ptr)) {
+      NS_ABORT_OOM(aSize);
+    }
+    return ptr;
+  }
+
+  static void* Realloc(void* aPtr, size_t aSize)
+  {
+    void* newptr = realloc(aPtr, aSize);
+    if (MOZ_UNLIKELY(!newptr && aSize)) {
+      NS_ABORT_OOM(aSize);
+    }
+    return newptr;
+  }
+
+  static void Free(void* aPtr) { free(aPtr); }
+  static void SizeTooBig(size_t aSize) { NS_ABORT_OOM(aSize); }
+};
+
+#endif
+
+// nsTArray_base stores elements into the space allocated beyond
+// sizeof(*this).  This is done to minimize the size of the nsTArray
+// object when it is empty.
+struct nsTArrayHeader
+{
+  static nsTArrayHeader sEmptyHdr;
+
+  uint32_t mLength;
+  uint32_t mCapacity : 31;
+  uint32_t mIsAutoArray : 1;
+};
+
+// This class provides a SafeElementAt method to nsTArray<T*> which does
+// not take a second default value parameter.
+template<class E, class Derived>
+struct nsTArray_SafeElementAtHelper
+{
+  typedef E*       elem_type;
+  typedef size_t   index_type;
+
+  // No implementation is provided for these two methods, and that is on
+  // purpose, since we don't support these functions on non-pointer type
+  // instantiations.
+  elem_type& SafeElementAt(index_type aIndex);
+  const elem_type& SafeElementAt(index_type aIndex) const;
+};
+
+template<class E, class Derived>
+struct nsTArray_SafeElementAtHelper<E*, Derived>
+{
+  typedef E*       elem_type;
+  //typedef const E* const_elem_type;   XXX: see below
+  typedef size_t   index_type;
+
+  elem_type SafeElementAt(index_type aIndex)
+  {
+    return static_cast<Derived*>(this)->SafeElementAt(aIndex, nullptr);
+  }
+
+  // XXX: Probably should return const_elem_type, but callsites must be fixed.
+  // Also, the use of const_elem_type for nsTArray<xpcGCCallback> in
+  // xpcprivate.h causes build failures on Windows because xpcGCCallback is a
+  // function pointer and MSVC doesn't like qualifying it with |const|.
+  elem_type SafeElementAt(index_type aIndex) const
+  {
+    return static_cast<const Derived*>(this)->SafeElementAt(aIndex, nullptr);
+  }
+};
+
+// E is the base type that the smart pointer is templated over; the
+// smart pointer can act as E*.
+template<class E, class Derived>
+struct nsTArray_SafeElementAtSmartPtrHelper
+{
+  typedef E*       elem_type;
+  typedef const E* const_elem_type;
+  typedef size_t   index_type;
+
+  elem_type SafeElementAt(index_type aIndex)
+  {
+    return static_cast<Derived*>(this)->SafeElementAt(aIndex, nullptr);
+  }
+
+  // XXX: Probably should return const_elem_type, but callsites must be fixed.
+  elem_type SafeElementAt(index_type aIndex) const
+  {
+    return static_cast<const Derived*>(this)->SafeElementAt(aIndex, nullptr);
+  }
+};
+
+template<class T> class nsCOMPtr;
+
+template<class E, class Derived>
+struct nsTArray_SafeElementAtHelper<nsCOMPtr<E>, Derived>
+  : public nsTArray_SafeElementAtSmartPtrHelper<E, Derived>
+{
+};
+
+template<class E, class Derived>
+struct nsTArray_SafeElementAtHelper<RefPtr<E>, Derived>
+  : public nsTArray_SafeElementAtSmartPtrHelper<E, Derived>
+{
+};
+
+namespace mozilla {
+template<class T> class OwningNonNull;
+} // namespace mozilla
+
+template<class E, class Derived>
+struct nsTArray_SafeElementAtHelper<mozilla::OwningNonNull<E>, Derived>
+{
+  typedef E*       elem_type;
+  typedef const E* const_elem_type;
+  typedef size_t   index_type;
+
+  elem_type SafeElementAt(index_type aIndex)
+  {
+    if (aIndex < static_cast<Derived*>(this)->Length()) {
+      return static_cast<Derived*>(this)->ElementAt(aIndex);
+    }
+    return nullptr;
+  }
+
+  // XXX: Probably should return const_elem_type, but callsites must be fixed.
+  elem_type SafeElementAt(index_type aIndex) const
+  {
+    if (aIndex < static_cast<const Derived*>(this)->Length()) {
+      return static_cast<const Derived*>(this)->ElementAt(aIndex);
+    }
+    return nullptr;
+  }
+};
+
+// Servo bindings.
+extern "C" void Gecko_EnsureTArrayCapacity(void* aArray,
+                                           size_t aCapacity,
+                                           size_t aElementSize);
+extern "C" void Gecko_ClearPODTArray(void* aArray,
+                                     size_t aElementSize,
+                                     size_t aElementAlign);
+
+MOZ_NORETURN MOZ_COLD void
+InvalidArrayIndex_CRASH(size_t aIndex, size_t aLength);
+
+//
+// This class serves as a base class for nsTArray.  It shouldn't be used
+// directly.  It holds common implementation code that does not depend on the
+// element type of the nsTArray.
+//
+template<class Alloc, class Copy>
+class nsTArray_base
+{
+  // Allow swapping elements with |nsTArray_base|s created using a
+  // different allocator.  This is kosher because all allocators use
+  // the same free().
+  template<class Allocator, class Copier>
+  friend class nsTArray_base;
+  friend void Gecko_EnsureTArrayCapacity(void* aArray, size_t aCapacity,
+                                         size_t aElemSize);
+  friend void Gecko_ClearPODTArray(void* aTArray, size_t aElementSize,
+                                   size_t aElementAlign);
+
+protected:
+  typedef nsTArrayHeader Header;
+
+public:
+  typedef size_t size_type;
+  typedef size_t index_type;
+
+  // @return The number of elements in the array.
+  size_type Length() const { return mHdr->mLength; }
+
+  // @return True if the array is empty or false otherwise.
+  bool IsEmpty() const { return Length() == 0; }
+
+  // @return The number of elements that can fit in the array without forcing
+  // the array to be re-allocated.  The length of an array is always less
+  // than or equal to its capacity.
+  size_type Capacity() const {  return mHdr->mCapacity; }
+
+#ifdef DEBUG
+  void* DebugGetHeader() const { return mHdr; }
+#endif
+
+protected:
+  nsTArray_base();
+
+  ~nsTArray_base();
+
+  // Resize the storage if necessary to achieve the requested capacity.
+  // @param aCapacity The requested number of array elements.
+  // @param aElemSize The size of an array element.
+  // @return False if insufficient memory is available; true otherwise.
+  template<typename ActualAlloc>
+  typename ActualAlloc::ResultTypeProxy EnsureCapacity(size_type aCapacity,
+                                                       size_type aElemSize);
+
+  // Tries to resize the storage to the minimum required amount. If this fails,
+  // the array is left as-is.
+  // @param aElemSize  The size of an array element.
+  // @param aElemAlign The alignment in bytes of an array element.
+  void ShrinkCapacity(size_type aElemSize, size_t aElemAlign);
+
+  // This method may be called to resize a "gap" in the array by shifting
+  // elements around.  It updates mLength appropriately.  If the resulting
+  // array has zero elements, then the array's memory is free'd.
+  // @param aStart     The starting index of the gap.
+  // @param aOldLen    The current length of the gap.
+  // @param aNewLen    The desired length of the gap.
+  // @param aElemSize  The size of an array element.
+  // @param aElemAlign The alignment in bytes of an array element.
+  template<typename ActualAlloc>
+  void ShiftData(index_type aStart, size_type aOldLen, size_type aNewLen,
+                 size_type aElemSize, size_t aElemAlign);
+
+  // This method increments the length member of the array's header.
+  // Note that mHdr may actually be sEmptyHdr in the case where a
+  // zero-length array is inserted into our array. But then aNum should
+  // always be 0.
+  void IncrementLength(size_t aNum)
+  {
+    if (mHdr == EmptyHdr()) {
+      if (MOZ_UNLIKELY(aNum != 0)) {
+        // Writing a non-zero length to the empty header would be extremely bad.
+        MOZ_CRASH();
+      }
+    } else {
+      mHdr->mLength += aNum;
+    }
+  }
+
+  // This method inserts blank slots into the array.
+  // @param aIndex the place to insert the new elements. This must be no
+  //               greater than the current length of the array.
+  // @param aCount the number of slots to insert
+  // @param aElementSize the size of an array element.
+  // @param aElemAlign the alignment in bytes of an array element.
+  template<typename ActualAlloc>
+  bool InsertSlotsAt(index_type aIndex, size_type aCount,
+                     size_type aElementSize, size_t aElemAlign);
+
+  template<typename ActualAlloc, class Allocator>
+  typename ActualAlloc::ResultTypeProxy
+  SwapArrayElements(nsTArray_base<Allocator, Copy>& aOther,
+                    size_type aElemSize,
+                    size_t aElemAlign);
+
+  // This is an RAII class used in SwapArrayElements.
+  class IsAutoArrayRestorer
+  {
+  public:
+    IsAutoArrayRestorer(nsTArray_base<Alloc, Copy>& aArray, size_t aElemAlign);
+    ~IsAutoArrayRestorer();
+
+  private:
+    nsTArray_base<Alloc, Copy>& mArray;
+    size_t mElemAlign;
+    bool mIsAuto;
+  };
+
+  // Helper function for SwapArrayElements. Ensures that if the array
+  // is an AutoTArray that it doesn't use the built-in buffer.
+  template<typename ActualAlloc>
+  bool EnsureNotUsingAutoArrayBuffer(size_type aElemSize);
+
+  // Returns true if this nsTArray is an AutoTArray with a built-in buffer.
+  bool IsAutoArray() const { return mHdr->mIsAutoArray; }
+
+  // Returns a Header for the built-in buffer of this AutoTArray.
+  Header* GetAutoArrayBuffer(size_t aElemAlign)
+  {
+    MOZ_ASSERT(IsAutoArray(), "Should be an auto array to call this");
+    return GetAutoArrayBufferUnsafe(aElemAlign);
+  }
+  const Header* GetAutoArrayBuffer(size_t aElemAlign) const
+  {
+    MOZ_ASSERT(IsAutoArray(), "Should be an auto array to call this");
+    return GetAutoArrayBufferUnsafe(aElemAlign);
+  }
+
+  // Returns a Header for the built-in buffer of this AutoTArray, but doesn't
+  // assert that we are an AutoTArray.
+  Header* GetAutoArrayBufferUnsafe(size_t aElemAlign)
+  {
+    return const_cast<Header*>(static_cast<const nsTArray_base<Alloc, Copy>*>(
+      this)->GetAutoArrayBufferUnsafe(aElemAlign));
+  }
+  const Header* GetAutoArrayBufferUnsafe(size_t aElemAlign) const;
+
+  // Returns true if this is an AutoTArray and it currently uses the
+  // built-in buffer to store its elements.
+  bool UsesAutoArrayBuffer() const;
+
+  // The array's elements (prefixed with a Header).  This pointer is never
+  // null.  If the array is empty, then this will point to sEmptyHdr.
+  Header* mHdr;
+
+  Header* Hdr() const { return mHdr; }
+  Header** PtrToHdr() { return &mHdr; }
+  static Header* EmptyHdr() { return &Header::sEmptyHdr; }
+};
+
+//
+// This class defines convenience functions for element specific operations.
+// Specialize this template if necessary.
+//
+template<class E>
+class nsTArrayElementTraits
+{
+public:
+  // Invoke the default constructor in place.
+  static inline void Construct(E* aE)
+  {
+    // Do NOT call "E()"! That triggers C++ "default initialization"
+    // which zeroes out POD ("plain old data") types such as regular
+    // ints.  We don't want that because it can be a performance issue
+    // and people don't expect it; nsTArray should work like a regular
+    // C/C++ array in this respect.
+    new (static_cast<void*>(aE)) E;
+  }
+  // Invoke the copy-constructor in place.
+  template<class A>
+  static inline void Construct(E* aE, A&& aArg)
+  {
+    typedef typename mozilla::RemoveCV<E>::Type E_NoCV;
+    typedef typename mozilla::RemoveCV<A>::Type A_NoCV;
+    static_assert(!mozilla::IsSame<E_NoCV*, A_NoCV>::value,
+                  "For safety, we disallow constructing nsTArray<E> elements "
+                  "from E* pointers. See bug 960591.");
+    new (static_cast<void*>(aE)) E(mozilla::Forward<A>(aArg));
+  }
+  // Invoke the destructor in place.
+  static inline void Destruct(E* aE) { aE->~E(); }
+};
+
+// The default comparator used by nsTArray
+template<class A, class B>
+class nsDefaultComparator
+{
+public:
+  bool Equals(const A& aA, const B& aB) const { return aA == aB; }
+  bool LessThan(const A& aA, const B& aB) const { return aA < aB; }
+};
+
+template<bool IsPod, bool IsSameType>
+struct AssignRangeAlgorithm
+{
+  template<class Item, class ElemType, class IndexType, class SizeType>
+  static void implementation(ElemType* aElements, IndexType aStart,
+                             SizeType aCount, const Item* aValues)
+  {
+    ElemType* iter = aElements + aStart;
+    ElemType* end = iter + aCount;
+    for (; iter != end; ++iter, ++aValues) {
+      nsTArrayElementTraits<ElemType>::Construct(iter, *aValues);
+    }
+  }
+};
+
+template<>
+struct AssignRangeAlgorithm<true, true>
+{
+  template<class Item, class ElemType, class IndexType, class SizeType>
+  static void implementation(ElemType* aElements, IndexType aStart,
+                             SizeType aCount, const Item* aValues)
+  {
+    memcpy(aElements + aStart, aValues, aCount * sizeof(ElemType));
+  }
+};
+
+//
+// Normally elements are copied with memcpy and memmove, but for some element
+// types that is problematic.  The nsTArray_CopyChooser template class can be
+// specialized to ensure that copying calls constructors and destructors
+// instead, as is done below for JS::Heap<E> elements.
+//
+
+//
+// A class that defines how to copy elements using memcpy/memmove.
+//
+struct nsTArray_CopyWithMemutils
+{
+  const static bool allowRealloc = true;
+
+  static void MoveNonOverlappingRegionWithHeader(void* aDest, const void* aSrc,
+                                                 size_t aCount, size_t aElemSize)
+  {
+    memcpy(aDest, aSrc, sizeof(nsTArrayHeader) + aCount * aElemSize);
+  }
+
+  static void MoveOverlappingRegion(void* aDest, void* aSrc, size_t aCount,
+                                    size_t aElemSize)
+  {
+    memmove(aDest, aSrc, aCount * aElemSize);
+  }
+
+  static void MoveNonOverlappingRegion(void* aDest, void* aSrc, size_t aCount,
+                                       size_t aElemSize)
+  {
+    memcpy(aDest, aSrc, aCount * aElemSize);
+  }
+};
+
+//
+// A template class that defines how to copy elements calling their constructors
+// and destructors appropriately.
+//
+template<class ElemType>
+struct nsTArray_CopyWithConstructors
+{
+  typedef nsTArrayElementTraits<ElemType> traits;
+
+  const static bool allowRealloc = false;
+
+  static void MoveNonOverlappingRegionWithHeader(void* aDest, void* aSrc, size_t aCount,
+                                                 size_t aElemSize)
+  {
+    nsTArrayHeader* destHeader = static_cast<nsTArrayHeader*>(aDest);
+    nsTArrayHeader* srcHeader = static_cast<nsTArrayHeader*>(aSrc);
+    *destHeader = *srcHeader;
+    MoveNonOverlappingRegion(static_cast<uint8_t*>(aDest) + sizeof(nsTArrayHeader),
+                             static_cast<uint8_t*>(aSrc) + sizeof(nsTArrayHeader),
+                             aCount, aElemSize);
+  }
+
+  // These functions are defined by analogy with memmove and memcpy.
+  // What they actually do is slightly different: MoveOverlappingRegion
+  // checks to see which direction the movement needs to take place,
+  // whether from back-to-front of the range to be moved or from
+  // front-to-back.  MoveNonOverlappingRegion assumes that moving
+  // front-to-back is always valid.  So they're really more like
+  // std::move{_backward,} in that respect.  We keep these names because
+  // we think they read slightly better, and MoveNonOverlappingRegion is
+  // only ever called on overlapping regions from MoveOverlappingRegion.
+  static void MoveOverlappingRegion(void* aDest, void* aSrc, size_t aCount,
+                                    size_t aElemSize)
+  {
+    ElemType* destElem = static_cast<ElemType*>(aDest);
+    ElemType* srcElem = static_cast<ElemType*>(aSrc);
+    ElemType* destElemEnd = destElem + aCount;
+    ElemType* srcElemEnd = srcElem + aCount;
+    if (destElem == srcElem) {
+      return;  // In practice, we don't do this.
+    }
+
+    // Figure out whether to copy back-to-front or front-to-back.
+    if (srcElemEnd > destElem && srcElemEnd < destElemEnd) {
+      while (destElemEnd != destElem) {
+        --destElemEnd;
+        --srcElemEnd;
+        traits::Construct(destElemEnd, mozilla::Move(*srcElemEnd));
+        traits::Destruct(srcElemEnd);
+      }
+    } else {
+      MoveNonOverlappingRegion(aDest, aSrc, aCount, aElemSize);
+    }
+  }
+
+  static void MoveNonOverlappingRegion(void* aDest, void* aSrc, size_t aCount,
+                                       size_t aElemSize)
+  {
+    ElemType* destElem = static_cast<ElemType*>(aDest);
+    ElemType* srcElem = static_cast<ElemType*>(aSrc);
+    ElemType* destElemEnd = destElem + aCount;
+#ifdef DEBUG
+    ElemType* srcElemEnd = srcElem + aCount;
+    MOZ_ASSERT(srcElemEnd <= destElem || srcElemEnd > destElemEnd);
+#endif
+    while (destElem != destElemEnd) {
+      traits::Construct(destElem, mozilla::Move(*srcElem));
+      traits::Destruct(srcElem);
+      ++destElem;
+      ++srcElem;
+    }
+  }
+};
+
+//
+// The default behaviour is to use memcpy/memmove for everything.
+//
+template<class E>
+struct MOZ_NEEDS_MEMMOVABLE_TYPE nsTArray_CopyChooser
+{
+  using Type = nsTArray_CopyWithMemutils;
+};
+
+//
+// Some classes require constructors/destructors to be called, so they are
+// specialized here.
+//
+#define DECLARE_USE_COPY_CONSTRUCTORS(T)                \
+  template<>                                            \
+  struct nsTArray_CopyChooser<T>                        \
+  {                                                     \
+    using Type = nsTArray_CopyWithConstructors<T>;      \
+  };
+
+#define DECLARE_USE_COPY_CONSTRUCTORS_FOR_TEMPLATE(T)   \
+  template<typename S>                                  \
+  struct nsTArray_CopyChooser<T<S>>                     \
+  {                                                     \
+    using Type = nsTArray_CopyWithConstructors<T<S>>;   \
+  };
+
+DECLARE_USE_COPY_CONSTRUCTORS_FOR_TEMPLATE(JS::Heap)
+
+DECLARE_USE_COPY_CONSTRUCTORS(nsRegion)
+DECLARE_USE_COPY_CONSTRUCTORS(nsIntRegion)
+DECLARE_USE_COPY_CONSTRUCTORS(mozilla::layers::TileClient)
+DECLARE_USE_COPY_CONSTRUCTORS(mozilla::SerializedStructuredCloneBuffer)
+DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::ipc::StructuredCloneData)
+DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::ClonedMessageData)
+DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::indexedDB::StructuredCloneReadInfo);
+DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::indexedDB::ObjectStoreCursorResponse)
+DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::indexedDB::SerializedStructuredCloneReadInfo);
+DECLARE_USE_COPY_CONSTRUCTORS(JSStructuredCloneData)
+DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::MessagePortMessage)
+DECLARE_USE_COPY_CONSTRUCTORS(JS::ObjectPtr)
+
+
+//
+// Base class for nsTArray_Impl that is templated on element type and derived
+// nsTArray_Impl class, to allow extra conversions to be added for specific
+// types.
+//
+template<class E, class Derived>
+struct nsTArray_TypedBase : public nsTArray_SafeElementAtHelper<E, Derived>
+{
+};
+
+//
+// Specialization of nsTArray_TypedBase for arrays containing JS::Heap<E>
+// elements.
+//
+// These conversions are safe because JS::Heap<E> and E share the same
+// representation, and since the result of the conversions are const references
+// we won't miss any barriers.
+//
+// The static_cast is necessary to obtain the correct address for the derived
+// class since we are a base class used in multiple inheritance.
+//
+template<class E, class Derived>
+struct nsTArray_TypedBase<JS::Heap<E>, Derived>
+  : public nsTArray_SafeElementAtHelper<JS::Heap<E>, Derived>
+{
+  operator const nsTArray<E>&()
+  {
+    static_assert(sizeof(E) == sizeof(JS::Heap<E>),
+                  "JS::Heap<E> must be binary compatible with E.");
+    Derived* self = static_cast<Derived*>(this);
+    return *reinterpret_cast<nsTArray<E> *>(self);
+  }
+
+  operator const FallibleTArray<E>&()
+  {
+    Derived* self = static_cast<Derived*>(this);
+    return *reinterpret_cast<FallibleTArray<E> *>(self);
+  }
+};
+
+namespace detail {
+
+template<class Item, class Comparator>
+struct ItemComparatorEq
+{
+  const Item& mItem;
+  const Comparator& mComp;
+  ItemComparatorEq(const Item& aItem, const Comparator& aComp)
+    : mItem(aItem)
+    , mComp(aComp)
+  {}
+  template<class T>
+  int operator()(const T& aElement) const {
+    if (mComp.Equals(aElement, mItem)) {
+      return 0;
+    }
+
+    return mComp.LessThan(aElement, mItem) ? 1 : -1;
+  }
+};
+
+template<class Item, class Comparator>
+struct ItemComparatorFirstElementGT
+{
+  const Item& mItem;
+  const Comparator& mComp;
+  ItemComparatorFirstElementGT(const Item& aItem, const Comparator& aComp)
+    : mItem(aItem)
+    , mComp(aComp)
+  {}
+  template<class T>
+  int operator()(const T& aElement) const {
+    if (mComp.LessThan(aElement, mItem) ||
+        mComp.Equals(aElement, mItem)) {
+      return 1;
+    } else {
+      return -1;
+    }
+  }
+};
+
+} // namespace detail
+
+//
+// nsTArray_Impl contains most of the guts supporting nsTArray, FallibleTArray,
+// AutoTArray.
+//
+// The only situation in which you might need to use nsTArray_Impl in your code
+// is if you're writing code which mutates a TArray which may or may not be
+// infallible.
+//
+// Code which merely reads from a TArray which may or may not be infallible can
+// simply cast the TArray to |const nsTArray&|; both fallible and infallible
+// TArrays can be cast to |const nsTArray&|.
+//
+template<class E, class Alloc>
+class nsTArray_Impl
+  : public nsTArray_base<Alloc, typename nsTArray_CopyChooser<E>::Type>
+  , public nsTArray_TypedBase<E, nsTArray_Impl<E, Alloc>>
+{
+private:
+  typedef nsTArrayFallibleAllocator FallibleAlloc;
+  typedef nsTArrayInfallibleAllocator InfallibleAlloc;
+
+public:
+  typedef typename nsTArray_CopyChooser<E>::Type     copy_type;
+  typedef nsTArray_base<Alloc, copy_type>            base_type;
+  typedef typename base_type::size_type              size_type;
+  typedef typename base_type::index_type             index_type;
+  typedef E                                          elem_type;
+  typedef nsTArray_Impl<E, Alloc>                    self_type;
+  typedef nsTArrayElementTraits<E>                   elem_traits;
+  typedef nsTArray_SafeElementAtHelper<E, self_type> safeelementat_helper_type;
+  typedef elem_type*                                 iterator;
+  typedef const elem_type*                           const_iterator;
+  typedef mozilla::ReverseIterator<elem_type*>       reverse_iterator;
+  typedef mozilla::ReverseIterator<const elem_type*> const_reverse_iterator;
+
+  using safeelementat_helper_type::SafeElementAt;
+  using base_type::EmptyHdr;
+
+  // A special value that is used to indicate an invalid or unknown index
+  // into the array.
+  static const index_type NoIndex = index_type(-1);
+
+  using base_type::Length;
+
+  //
+  // Finalization method
+  //
+
+  ~nsTArray_Impl() { Clear(); }
+
+  //
+  // Initialization methods
+  //
+
+  nsTArray_Impl() {}
+
+  // Initialize this array and pre-allocate some number of elements.
+  explicit nsTArray_Impl(size_type aCapacity) { SetCapacity(aCapacity); }
+
+  // Initialize this array with an r-value.
+  // Allow different types of allocators, since the allocator doesn't matter.
+  template<typename Allocator>
+  explicit nsTArray_Impl(nsTArray_Impl<E, Allocator>&& aOther)
+  {
+    SwapElements(aOther);
+  }
+
+  // The array's copy-constructor performs a 'deep' copy of the given array.
+  // @param aOther The array object to copy.
+  //
+  // It's very important that we declare this method as taking |const
+  // self_type&| as opposed to taking |const nsTArray_Impl<E, OtherAlloc>| for
+  // an arbitrary OtherAlloc.
+  //
+  // If we don't declare a constructor taking |const self_type&|, C++ generates
+  // a copy-constructor for this class which merely copies the object's
+  // members, which is obviously wrong.
+  //
+  // You can pass an nsTArray_Impl<E, OtherAlloc> to this method because
+  // nsTArray_Impl<E, X> can be cast to const nsTArray_Impl<E, Y>&.  So the
+  // effect on the API is the same as if we'd declared this method as taking
+  // |const nsTArray_Impl<E, OtherAlloc>&|.
+  explicit nsTArray_Impl(const self_type& aOther) { AppendElements(aOther); }
+
+  explicit nsTArray_Impl(std::initializer_list<E> aIL) { AppendElements(aIL.begin(), aIL.size()); }
+  // Allow converting to a const array with a different kind of allocator,
+  // Since the allocator doesn't matter for const arrays
+  template<typename Allocator>
+  operator const nsTArray_Impl<E, Allocator>&() const
+  {
+    return *reinterpret_cast<const nsTArray_Impl<E, Allocator>*>(this);
+  }
+  // And we have to do this for our subclasses too
+  operator const nsTArray<E>&() const
+  {
+    return *reinterpret_cast<const InfallibleTArray<E>*>(this);
+  }
+  operator const FallibleTArray<E>&() const
+  {
+    return *reinterpret_cast<const FallibleTArray<E>*>(this);
+  }
+
+  // The array's assignment operator performs a 'deep' copy of the given
+  // array.  It is optimized to reuse existing storage if possible.
+  // @param aOther The array object to copy.
+  self_type& operator=(const self_type& aOther)
+  {
+    if (this != &aOther) {
+      ReplaceElementsAt(0, Length(), aOther.Elements(), aOther.Length());
+    }
+    return *this;
+  }
+
+  // The array's move assignment operator steals the underlying data from
+  // the other array.
+  // @param other  The array object to move from.
+  self_type& operator=(self_type&& aOther)
+  {
+    if (this != &aOther) {
+      Clear();
+      SwapElements(aOther);
+    }
+    return *this;
+  }
+
+  // Return true if this array has the same length and the same
+  // elements as |aOther|.
+  template<typename Allocator>
+  bool operator==(const nsTArray_Impl<E, Allocator>& aOther) const
+  {
+    size_type len = Length();
+    if (len != aOther.Length()) {
+      return false;
+    }
+
+    // XXX std::equal would be as fast or faster here
+    for (index_type i = 0; i < len; ++i) {
+      if (!(operator[](i) == aOther[i])) {
+        return false;
+      }
+    }
+
+    return true;
+  }
+
+  // Return true if this array does not have the same length and the same
+  // elements as |aOther|.
+  bool operator!=(const self_type& aOther) const { return !operator==(aOther); }
+
+  template<typename Allocator>
+  self_type& operator=(const nsTArray_Impl<E, Allocator>& aOther)
+  {
+    ReplaceElementsAt(0, Length(), aOther.Elements(), aOther.Length());
+    return *this;
+  }
+
+  template<typename Allocator>
+  self_type& operator=(nsTArray_Impl<E, Allocator>&& aOther)
+  {
+    Clear();
+    SwapElements(aOther);
+    return *this;
+  }
+
+  // @return The amount of memory used by this nsTArray_Impl, excluding
+  // sizeof(*this). If you want to measure anything hanging off the array, you
+  // must iterate over the elements and measure them individually; hence the
+  // "Shallow" prefix.
+  size_t ShallowSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    if (this->UsesAutoArrayBuffer() || Hdr() == EmptyHdr()) {
+      return 0;
+    }
+    return aMallocSizeOf(this->Hdr());
+  }
+
+  // @return The amount of memory used by this nsTArray_Impl, including
+  // sizeof(*this). If you want to measure anything hanging off the array, you
+  // must iterate over the elements and measure them individually; hence the
+  // "Shallow" prefix.
+  size_t ShallowSizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return aMallocSizeOf(this) + ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  //
+  // Accessor methods
+  //
+
+  // This method provides direct access to the array elements.
+  // @return A pointer to the first element of the array.  If the array is
+  // empty, then this pointer must not be dereferenced.
+  elem_type* Elements() { return reinterpret_cast<elem_type*>(Hdr() + 1); }
+
+  // This method provides direct, readonly access to the array elements.
+  // @return A pointer to the first element of the array.  If the array is
+  // empty, then this pointer must not be dereferenced.
+  const elem_type* Elements() const
+  {
+    return reinterpret_cast<const elem_type*>(Hdr() + 1);
+  }
+
+  // This method provides direct access to an element of the array. The given
+  // index must be within the array bounds.
+  // @param aIndex The index of an element in the array.
+  // @return A reference to the i'th element of the array.
+  elem_type& ElementAt(index_type aIndex)
+  {
+    if (MOZ_UNLIKELY(aIndex >= Length())) {
+      InvalidArrayIndex_CRASH(aIndex, Length());
+    }
+    return Elements()[aIndex];
+  }
+
+  // This method provides direct, readonly access to an element of the array
+  // The given index must be within the array bounds.
+  // @param aIndex The index of an element in the array.
+  // @return A const reference to the i'th element of the array.
+  const elem_type& ElementAt(index_type aIndex) const
+  {
+    if (MOZ_UNLIKELY(aIndex >= Length())) {
+      InvalidArrayIndex_CRASH(aIndex, Length());
+    }
+    return Elements()[aIndex];
+  }
+
+  // This method provides direct access to an element of the array in a bounds
+  // safe manner. If the requested index is out of bounds the provided default
+  // value is returned.
+  // @param aIndex The index of an element in the array.
+  // @param aDef   The value to return if the index is out of bounds.
+  elem_type& SafeElementAt(index_type aIndex, elem_type& aDef)
+  {
+    return aIndex < Length() ? Elements()[aIndex] : aDef;
+  }
+
+  // This method provides direct access to an element of the array in a bounds
+  // safe manner. If the requested index is out of bounds the provided default
+  // value is returned.
+  // @param aIndex The index of an element in the array.
+  // @param aDef   The value to return if the index is out of bounds.
+  const elem_type& SafeElementAt(index_type aIndex, const elem_type& aDef) const
+  {
+    return aIndex < Length() ? Elements()[aIndex] : aDef;
+  }
+
+  // Shorthand for ElementAt(aIndex)
+  elem_type& operator[](index_type aIndex) { return ElementAt(aIndex); }
+
+  // Shorthand for ElementAt(aIndex)
+  const elem_type& operator[](index_type aIndex) const { return ElementAt(aIndex); }
+
+  // Shorthand for ElementAt(length - 1)
+  elem_type& LastElement() { return ElementAt(Length() - 1); }
+
+  // Shorthand for ElementAt(length - 1)
+  const elem_type& LastElement() const { return ElementAt(Length() - 1); }
+
+  // Shorthand for SafeElementAt(length - 1, def)
+  elem_type& SafeLastElement(elem_type& aDef)
+  {
+    return SafeElementAt(Length() - 1, aDef);
+  }
+
+  // Shorthand for SafeElementAt(length - 1, def)
+  const elem_type& SafeLastElement(const elem_type& aDef) const
+  {
+    return SafeElementAt(Length() - 1, aDef);
+  }
+
+  // Methods for range-based for loops.
+  iterator begin() { return Elements(); }
+  const_iterator begin() const { return Elements(); }
+  const_iterator cbegin() const { return begin(); }
+  iterator end() { return Elements() + Length(); }
+  const_iterator end() const { return Elements() + Length(); }
+  const_iterator cend() const { return end(); }
+
+  // Methods for reverse iterating.
+  reverse_iterator rbegin() { return reverse_iterator(end()); }
+  const_reverse_iterator rbegin() const { return const_reverse_iterator(end()); }
+  const_reverse_iterator crbegin() const { return rbegin(); }
+  reverse_iterator rend() { return reverse_iterator(begin()); }
+  const_reverse_iterator rend() const { return const_reverse_iterator(begin()); }
+  const_reverse_iterator crend() const { return rend(); }
+
+  //
+  // Search methods
+  //
+
+  // This method searches for the first element in this array that is equal
+  // to the given element.
+  // @param aItem  The item to search for.
+  // @param aComp  The Comparator used to determine element equality.
+  // @return       true if the element was found.
+  template<class Item, class Comparator>
+  bool Contains(const Item& aItem, const Comparator& aComp) const
+  {
+    return IndexOf(aItem, 0, aComp) != NoIndex;
+  }
+
+  // This method searches for the first element in this array that is equal
+  // to the given element.  This method assumes that 'operator==' is defined
+  // for elem_type.
+  // @param aItem  The item to search for.
+  // @return       true if the element was found.
+  template<class Item>
+  bool Contains(const Item& aItem) const
+  {
+    return IndexOf(aItem) != NoIndex;
+  }
+
+  // This method searches for the offset of the first element in this
+  // array that is equal to the given element.
+  // @param aItem  The item to search for.
+  // @param aStart The index to start from.
+  // @param aComp  The Comparator used to determine element equality.
+  // @return       The index of the found element or NoIndex if not found.
+  template<class Item, class Comparator>
+  index_type IndexOf(const Item& aItem, index_type aStart,
+                     const Comparator& aComp) const
+  {
+    const elem_type* iter = Elements() + aStart;
+    const elem_type* iend = Elements() + Length();
+    for (; iter != iend; ++iter) {
+      if (aComp.Equals(*iter, aItem)) {
+        return index_type(iter - Elements());
+      }
+    }
+    return NoIndex;
+  }
+
+  // This method searches for the offset of the first element in this
+  // array that is equal to the given element.  This method assumes
+  // that 'operator==' is defined for elem_type.
+  // @param aItem  The item to search for.
+  // @param aStart The index to start from.
+  // @return       The index of the found element or NoIndex if not found.
+  template<class Item>
+  index_type IndexOf(const Item& aItem, index_type aStart = 0) const
+  {
+    return IndexOf(aItem, aStart, nsDefaultComparator<elem_type, Item>());
+  }
+
+  // This method searches for the offset of the last element in this
+  // array that is equal to the given element.
+  // @param aItem  The item to search for.
+  // @param aStart The index to start from.  If greater than or equal to the
+  //               length of the array, then the entire array is searched.
+  // @param aComp  The Comparator used to determine element equality.
+  // @return       The index of the found element or NoIndex if not found.
+  template<class Item, class Comparator>
+  index_type LastIndexOf(const Item& aItem, index_type aStart,
+                         const Comparator& aComp) const
+  {
+    size_type endOffset = aStart >= Length() ? Length() : aStart + 1;
+    const elem_type* iend = Elements() - 1;
+    const elem_type* iter = iend + endOffset;
+    for (; iter != iend; --iter) {
+      if (aComp.Equals(*iter, aItem)) {
+        return index_type(iter - Elements());
+      }
+    }
+    return NoIndex;
+  }
+
+  // This method searches for the offset of the last element in this
+  // array that is equal to the given element.  This method assumes
+  // that 'operator==' is defined for elem_type.
+  // @param aItem  The item to search for.
+  // @param aStart The index to start from.  If greater than or equal to the
+  //               length of the array, then the entire array is searched.
+  // @return       The index of the found element or NoIndex if not found.
+  template<class Item>
+  index_type LastIndexOf(const Item& aItem,
+                         index_type aStart = NoIndex) const
+  {
+    return LastIndexOf(aItem, aStart, nsDefaultComparator<elem_type, Item>());
+  }
+
+  // This method searches for the offset for the element in this array
+  // that is equal to the given element. The array is assumed to be sorted.
+  // If there is more than one equivalent element, there is no guarantee
+  // on which one will be returned.
+  // @param aItem  The item to search for.
+  // @param aComp  The Comparator used.
+  // @return       The index of the found element or NoIndex if not found.
+  template<class Item, class Comparator>
+  index_type BinaryIndexOf(const Item& aItem, const Comparator& aComp) const
+  {
+    using mozilla::BinarySearchIf;
+    typedef ::detail::ItemComparatorEq<Item, Comparator> Cmp;
+
+    size_t index;
+    bool found = BinarySearchIf(*this, 0, Length(), Cmp(aItem, aComp), &index);
+    return found ? index : NoIndex;
+  }
+
+  // This method searches for the offset for the element in this array
+  // that is equal to the given element. The array is assumed to be sorted.
+  // This method assumes that 'operator==' and 'operator<' are defined.
+  // @param aItem  The item to search for.
+  // @return       The index of the found element or NoIndex if not found.
+  template<class Item>
+  index_type BinaryIndexOf(const Item& aItem) const
+  {
+    return BinaryIndexOf(aItem, nsDefaultComparator<elem_type, Item>());
+  }
+
+  //
+  // Mutation methods
+  //
+
+  template<class Allocator, typename ActualAlloc = Alloc>
+  typename ActualAlloc::ResultType Assign(
+      const nsTArray_Impl<E, Allocator>& aOther)
+  {
+    return ActualAlloc::ConvertBoolToResultType(
+      !!ReplaceElementsAt<E, ActualAlloc>(0, Length(),
+                                          aOther.Elements(), aOther.Length()));
+  }
+
+  template<class Allocator>
+  MOZ_MUST_USE
+  bool Assign(const nsTArray_Impl<E, Allocator>& aOther,
+              const mozilla::fallible_t&)
+  {
+    return Assign<Allocator, FallibleAlloc>(aOther);
+  }
+
+  template<class Allocator>
+  void Assign(nsTArray_Impl<E, Allocator>&& aOther)
+  {
+    Clear();
+    SwapElements(aOther);
+  }
+
+  // This method call the destructor on each element of the array, empties it,
+  // but does not shrink the array's capacity.
+  // See also SetLengthAndRetainStorage.
+  // Make sure to call Compact() if needed to avoid keeping a huge array
+  // around.
+  void ClearAndRetainStorage()
+  {
+    if (base_type::mHdr == EmptyHdr()) {
+      return;
+    }
+
+    DestructRange(0, Length());
+    base_type::mHdr->mLength = 0;
+  }
+
+  // This method modifies the length of the array, but unlike SetLength
+  // it doesn't deallocate/reallocate the current internal storage.
+  // The new length MUST be shorter than or equal to the current capacity.
+  // If the new length is larger than the existing length of the array,
+  // then new elements will be constructed using elem_type's default
+  // constructor.  If shorter, elements will be destructed and removed.
+  // See also ClearAndRetainStorage.
+  // @param aNewLen  The desired length of this array.
+  void SetLengthAndRetainStorage(size_type aNewLen)
+  {
+    MOZ_ASSERT(aNewLen <= base_type::Capacity());
+    size_type oldLen = Length();
+    if (aNewLen > oldLen) {
+      InsertElementsAt(oldLen, aNewLen - oldLen);
+      return;
+    }
+    if (aNewLen < oldLen) {
+      DestructRange(aNewLen, oldLen - aNewLen);
+      base_type::mHdr->mLength = aNewLen;
+    }
+  }
+
+  // This method replaces a range of elements in this array.
+  // @param aStart    The starting index of the elements to replace.
+  // @param aCount    The number of elements to replace.  This may be zero to
+  //                  insert elements without removing any existing elements.
+  // @param aArray    The values to copy into this array.  Must be non-null,
+  //                  and these elements must not already exist in the array
+  //                  being modified.
+  // @param aArrayLen The number of values to copy into this array.
+  // @return          A pointer to the new elements in the array, or null if
+  //                  the operation failed due to insufficient memory.
+protected:
+  template<class Item, typename ActualAlloc = Alloc>
+  elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
+                               const Item* aArray, size_type aArrayLen);
+
+public:
+
+  template<class Item>
+  MOZ_MUST_USE
+  elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
+                               const Item* aArray, size_type aArrayLen,
+                               const mozilla::fallible_t&)
+  {
+    return ReplaceElementsAt<Item, FallibleAlloc>(aStart, aCount,
+                                                  aArray, aArrayLen);
+  }
+
+  // A variation on the ReplaceElementsAt method defined above.
+protected:
+  template<class Item, typename ActualAlloc = Alloc>
+  elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
+                               const nsTArray<Item>& aArray)
+  {
+    return ReplaceElementsAt<Item, ActualAlloc>(
+      aStart, aCount, aArray.Elements(), aArray.Length());
+  }
+public:
+
+  template<class Item>
+  MOZ_MUST_USE
+  elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
+                               const nsTArray<Item>& aArray,
+                               const mozilla::fallible_t&)
+  {
+    return ReplaceElementsAt<Item, FallibleAlloc>(aStart, aCount, aArray);
+  }
+
+  // A variation on the ReplaceElementsAt method defined above.
+protected:
+  template<class Item, typename ActualAlloc = Alloc>
+  elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
+                               const Item& aItem)
+  {
+    return ReplaceElementsAt<Item, ActualAlloc>(aStart, aCount, &aItem, 1);
+  }
+public:
+
+  template<class Item>
+  MOZ_MUST_USE
+  elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
+                               const Item& aItem, const mozilla::fallible_t&)
+  {
+    return ReplaceElementsAt<Item, FallibleAlloc>(aStart, aCount, aItem);
+  }
+
+  // A variation on the ReplaceElementsAt method defined above.
+  template<class Item>
+  elem_type* ReplaceElementAt(index_type aIndex, const Item& aItem)
+  {
+    return ReplaceElementsAt(aIndex, 1, &aItem, 1);
+  }
+
+  // A variation on the ReplaceElementsAt method defined above.
+protected:
+  template<class Item, typename ActualAlloc = Alloc>
+  elem_type* InsertElementsAt(index_type aIndex, const Item* aArray,
+                              size_type aArrayLen)
+  {
+    return ReplaceElementsAt<Item, ActualAlloc>(aIndex, 0, aArray, aArrayLen);
+  }
+public:
+
+  template<class Item>
+  MOZ_MUST_USE
+  elem_type* InsertElementsAt(index_type aIndex, const Item* aArray,
+                              size_type aArrayLen, const mozilla::fallible_t&)
+  {
+    return InsertElementsAt<Item, FallibleAlloc>(aIndex, aArray, aArrayLen);
+  }
+
+  // A variation on the ReplaceElementsAt method defined above.
+protected:
+  template<class Item, class Allocator, typename ActualAlloc = Alloc>
+  elem_type* InsertElementsAt(index_type aIndex,
+                              const nsTArray_Impl<Item, Allocator>& aArray)
+  {
+    return ReplaceElementsAt<Item, ActualAlloc>(
+      aIndex, 0, aArray.Elements(), aArray.Length());
+  }
+public:
+
+  template<class Item, class Allocator>
+  MOZ_MUST_USE
+  elem_type* InsertElementsAt(index_type aIndex,
+                              const nsTArray_Impl<Item, Allocator>& aArray,
+                              const mozilla::fallible_t&)
+  {
+    return InsertElementsAt<Item, Allocator, FallibleAlloc>(aIndex, aArray);
+  }
+
+  // Insert a new element without copy-constructing. This is useful to avoid
+  // temporaries.
+  // @return A pointer to the newly inserted element, or null on OOM.
+protected:
+  template<typename ActualAlloc = Alloc>
+  elem_type* InsertElementAt(index_type aIndex);
+
+public:
+
+  MOZ_MUST_USE
+  elem_type* InsertElementAt(index_type aIndex, const mozilla::fallible_t&)
+  {
+    return InsertElementAt<FallibleAlloc>(aIndex);
+  }
+
+  // Insert a new element, move constructing if possible.
+protected:
+  template<class Item, typename ActualAlloc = Alloc>
+  elem_type* InsertElementAt(index_type aIndex, Item&& aItem);
+
+public:
+
+  template<class Item>
+  MOZ_MUST_USE
+  elem_type* InsertElementAt(index_type aIndex, Item&& aItem,
+                             const mozilla::fallible_t&)
+  {
+    return InsertElementAt<Item, FallibleAlloc>(aIndex,
+                                                mozilla::Forward<Item>(aItem));
+  }
+
+  // This method searches for the smallest index of an element that is strictly
+  // greater than |aItem|. If |aItem| is inserted at this index, the array will
+  // remain sorted and |aItem| would come after all elements that are equal to
+  // it. If |aItem| is greater than or equal to all elements in the array, the
+  // array length is returned.
+  //
+  // Note that consumers who want to know whether there are existing items equal
+  // to |aItem| in the array can just check that the return value here is > 0
+  // and indexing into the previous slot gives something equal to |aItem|.
+  //
+  //
+  // @param aItem  The item to search for.
+  // @param aComp  The Comparator used.
+  // @return        The index of greatest element <= to |aItem|
+  // @precondition The array is sorted
+  template<class Item, class Comparator>
+  index_type IndexOfFirstElementGt(const Item& aItem,
+                                   const Comparator& aComp) const
+  {
+    using mozilla::BinarySearchIf;
+    typedef ::detail::ItemComparatorFirstElementGT<Item, Comparator> Cmp;
+
+    size_t index;
+    BinarySearchIf(*this, 0, Length(), Cmp(aItem, aComp), &index);
+    return index;
+  }
+
+  // A variation on the IndexOfFirstElementGt method defined above.
+  template<class Item>
+  index_type
+  IndexOfFirstElementGt(const Item& aItem) const
+  {
+    return IndexOfFirstElementGt(aItem, nsDefaultComparator<elem_type, Item>());
+  }
+
+  // Inserts |aItem| at such an index to guarantee that if the array
+  // was previously sorted, it will remain sorted after this
+  // insertion.
+protected:
+  template<class Item, class Comparator, typename ActualAlloc = Alloc>
+  elem_type* InsertElementSorted(Item&& aItem, const Comparator& aComp)
+  {
+    index_type index = IndexOfFirstElementGt<Item, Comparator>(aItem, aComp);
+    return InsertElementAt<Item, ActualAlloc>(
+      index, mozilla::Forward<Item>(aItem));
+  }
+public:
+
+  template<class Item, class Comparator>
+  MOZ_MUST_USE
+  elem_type* InsertElementSorted(Item&& aItem, const Comparator& aComp,
+                                 const mozilla::fallible_t&)
+  {
+    return InsertElementSorted<Item, Comparator, FallibleAlloc>(
+      mozilla::Forward<Item>(aItem), aComp);
+  }
+
+  // A variation on the InsertElementSorted method defined above.
+protected:
+  template<class Item, typename ActualAlloc = Alloc>
+  elem_type* InsertElementSorted(Item&& aItem)
+  {
+    nsDefaultComparator<elem_type, Item> comp;
+    return InsertElementSorted<Item, decltype(comp), ActualAlloc>(
+      mozilla::Forward<Item>(aItem), comp);
+  }
+public:
+
+  template<class Item>
+  MOZ_MUST_USE
+  elem_type* InsertElementSorted(Item&& aItem, const mozilla::fallible_t&)
+  {
+    return InsertElementSorted<Item, FallibleAlloc>(
+      mozilla::Forward<Item>(aItem));
+  }
+
+  // This method appends elements to the end of this array.
+  // @param aArray    The elements to append to this array.
+  // @param aArrayLen The number of elements to append to this array.
+  // @return          A pointer to the new elements in the array, or null if
+  //                  the operation failed due to insufficient memory.
+protected:
+  template<class Item, typename ActualAlloc = Alloc>
+  elem_type* AppendElements(const Item* aArray, size_type aArrayLen);
+
+public:
+
+  template<class Item>
+  /* MOZ_MUST_USE */
+  elem_type* AppendElements(const Item* aArray, size_type aArrayLen,
+                            const mozilla::fallible_t&)
+  {
+    return AppendElements<Item, FallibleAlloc>(aArray, aArrayLen);
+  }
+
+  // A variation on the AppendElements method defined above.
+protected:
+  template<class Item, class Allocator, typename ActualAlloc = Alloc>
+  elem_type* AppendElements(const nsTArray_Impl<Item, Allocator>& aArray)
+  {
+    return AppendElements<Item, ActualAlloc>(aArray.Elements(), aArray.Length());
+  }
+public:
+
+  template<class Item, class Allocator>
+  /* MOZ_MUST_USE */
+  elem_type* AppendElements(const nsTArray_Impl<Item, Allocator>& aArray,
+                            const mozilla::fallible_t&)
+  {
+    return AppendElements<Item, Allocator, FallibleAlloc>(aArray);
+  }
+
+  // Move all elements from another array to the end of this array.
+  // @return A pointer to the newly appended elements, or null on OOM.
+protected:
+  template<class Item, class Allocator, typename ActualAlloc = Alloc>
+  elem_type* AppendElements(nsTArray_Impl<Item, Allocator>&& aArray);
+
+public:
+
+  template<class Item, class Allocator, typename ActualAlloc = Alloc>
+  /* MOZ_MUST_USE */
+  elem_type* AppendElements(nsTArray_Impl<Item, Allocator>&& aArray,
+                            const mozilla::fallible_t&)
+  {
+    return AppendElements<Item, Allocator>(mozilla::Move(aArray));
+  }
+
+  // Append a new element, move constructing if possible.
+protected:
+  template<class Item, typename ActualAlloc = Alloc>
+  elem_type* AppendElement(Item&& aItem);
+
+public:
+
+  template<class Item>
+  /* MOZ_MUST_USE */
+  elem_type* AppendElement(Item&& aItem,
+                           const mozilla::fallible_t&)
+  {
+    return AppendElement<Item, FallibleAlloc>(mozilla::Forward<Item>(aItem));
+  }
+
+  // Append new elements without copy-constructing. This is useful to avoid
+  // temporaries.
+  // @return A pointer to the newly appended elements, or null on OOM.
+protected:
+  template<typename ActualAlloc = Alloc>
+  elem_type* AppendElements(size_type aCount) {
+    if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>(
+          Length() + aCount, sizeof(elem_type)))) {
+      return nullptr;
+    }
+    elem_type* elems = Elements() + Length();
+    size_type i;
+    for (i = 0; i < aCount; ++i) {
+      elem_traits::Construct(elems + i);
+    }
+    this->IncrementLength(aCount);
+    return elems;
+  }
+public:
+
+  /* MOZ_MUST_USE */
+  elem_type* AppendElements(size_type aCount,
+                            const mozilla::fallible_t&)
+  {
+    return AppendElements<FallibleAlloc>(aCount);
+  }
+
+  // Append a new element without copy-constructing. This is useful to avoid
+  // temporaries.
+  // @return A pointer to the newly appended element, or null on OOM.
+protected:
+  template<typename ActualAlloc = Alloc>
+  elem_type* AppendElement()
+  {
+    return AppendElements<ActualAlloc>(1);
+  }
+public:
+
+  /* MOZ_MUST_USE */
+  elem_type* AppendElement(const mozilla::fallible_t&)
+  {
+    return AppendElement<FallibleAlloc>();
+  }
+
+  // This method removes a range of elements from this array.
+  // @param aStart The starting index of the elements to remove.
+  // @param aCount The number of elements to remove.
+  void RemoveElementsAt(index_type aStart, size_type aCount);
+
+  // A variation on the RemoveElementsAt method defined above.
+  void RemoveElementAt(index_type aIndex) { RemoveElementsAt(aIndex, 1); }
+
+  // A variation on the RemoveElementsAt method defined above.
+  void Clear() { RemoveElementsAt(0, Length()); }
+
+  // This method removes elements based on the return value of the
+  // callback function aPredicate. If the function returns true for
+  // an element, the element is removed. aPredicate will be called
+  // for each element in order. It is not safe to access the array
+  // inside aPredicate.
+  template<typename Predicate>
+  void RemoveElementsBy(Predicate aPredicate);
+
+  // This helper function combines IndexOf with RemoveElementAt to "search
+  // and destroy" the first element that is equal to the given element.
+  // @param aItem The item to search for.
+  // @param aComp The Comparator used to determine element equality.
+  // @return true if the element was found
+  template<class Item, class Comparator>
+  bool RemoveElement(const Item& aItem, const Comparator& aComp)
+  {
+    index_type i = IndexOf(aItem, 0, aComp);
+    if (i == NoIndex) {
+      return false;
+    }
+
+    RemoveElementAt(i);
+    return true;
+  }
+
+  // A variation on the RemoveElement method defined above that assumes
+  // that 'operator==' is defined for elem_type.
+  template<class Item>
+  bool RemoveElement(const Item& aItem)
+  {
+    return RemoveElement(aItem, nsDefaultComparator<elem_type, Item>());
+  }
+
+  // This helper function combines IndexOfFirstElementGt with
+  // RemoveElementAt to "search and destroy" the last element that
+  // is equal to the given element.
+  // @param aItem The item to search for.
+  // @param aComp The Comparator used to determine element equality.
+  // @return true if the element was found
+  template<class Item, class Comparator>
+  bool RemoveElementSorted(const Item& aItem, const Comparator& aComp)
+  {
+    index_type index = IndexOfFirstElementGt(aItem, aComp);
+    if (index > 0 && aComp.Equals(ElementAt(index - 1), aItem)) {
+      RemoveElementAt(index - 1);
+      return true;
+    }
+    return false;
+  }
+
+  // A variation on the RemoveElementSorted method defined above.
+  template<class Item>
+  bool RemoveElementSorted(const Item& aItem)
+  {
+    return RemoveElementSorted(aItem, nsDefaultComparator<elem_type, Item>());
+  }
+
+  // This method causes the elements contained in this array and the given
+  // array to be swapped.
+  template<class Allocator>
+  typename Alloc::ResultType SwapElements(nsTArray_Impl<E, Allocator>& aOther)
+  {
+    return Alloc::Result(this->template SwapArrayElements<Alloc>(
+      aOther, sizeof(elem_type), MOZ_ALIGNOF(elem_type)));
+  }
+
+  //
+  // Allocation
+  //
+
+  // This method may increase the capacity of this array object by the
+  // specified amount.  This method may be called in advance of several
+  // AppendElement operations to minimize heap re-allocations.  This method
+  // will not reduce the number of elements in this array.
+  // @param aCapacity The desired capacity of this array.
+  // @return True if the operation succeeded; false if we ran out of memory
+protected:
+  template<typename ActualAlloc = Alloc>
+  typename ActualAlloc::ResultType SetCapacity(size_type aCapacity)
+  {
+    return ActualAlloc::Result(this->template EnsureCapacity<ActualAlloc>(
+      aCapacity, sizeof(elem_type)));
+  }
+public:
+
+  MOZ_MUST_USE
+  bool SetCapacity(size_type aCapacity, const mozilla::fallible_t&)
+  {
+    return SetCapacity<FallibleAlloc>(aCapacity);
+  }
+
+  // This method modifies the length of the array.  If the new length is
+  // larger than the existing length of the array, then new elements will be
+  // constructed using elem_type's default constructor.  Otherwise, this call
+  // removes elements from the array (see also RemoveElementsAt).
+  // @param aNewLen The desired length of this array.
+  // @return True if the operation succeeded; false otherwise.
+  // See also TruncateLength if the new length is guaranteed to be smaller than
+  // the old.
+protected:
+  template<typename ActualAlloc = Alloc>
+  typename ActualAlloc::ResultType SetLength(size_type aNewLen)
+  {
+    size_type oldLen = Length();
+    if (aNewLen > oldLen) {
+      return ActualAlloc::ConvertBoolToResultType(
+        InsertElementsAt<ActualAlloc>(oldLen, aNewLen - oldLen) != nullptr);
+    }
+
+    TruncateLength(aNewLen);
+    return ActualAlloc::ConvertBoolToResultType(true);
+  }
+public:
+
+  MOZ_MUST_USE
+  bool SetLength(size_type aNewLen, const mozilla::fallible_t&)
+  {
+    return SetLength<FallibleAlloc>(aNewLen);
+  }
+
+  // This method modifies the length of the array, but may only be
+  // called when the new length is shorter than the old.  It can
+  // therefore be called when elem_type has no default constructor,
+  // unlike SetLength.  It removes elements from the array (see also
+  // RemoveElementsAt).
+  // @param aNewLen The desired length of this array.
+  void TruncateLength(size_type aNewLen)
+  {
+    size_type oldLen = Length();
+    MOZ_ASSERT(aNewLen <= oldLen,
+               "caller should use SetLength instead");
+    RemoveElementsAt(aNewLen, oldLen - aNewLen);
+  }
+
+  // This method ensures that the array has length at least the given
+  // length.  If the current length is shorter than the given length,
+  // then new elements will be constructed using elem_type's default
+  // constructor.
+  // @param aMinLen The desired minimum length of this array.
+  // @return True if the operation succeeded; false otherwise.
+protected:
+  template<typename ActualAlloc = Alloc>
+  typename ActualAlloc::ResultType EnsureLengthAtLeast(size_type aMinLen)
+  {
+    size_type oldLen = Length();
+    if (aMinLen > oldLen) {
+      return ActualAlloc::ConvertBoolToResultType(
+        !!InsertElementsAt<ActualAlloc>(oldLen, aMinLen - oldLen));
+    }
+    return ActualAlloc::ConvertBoolToResultType(true);
+  }
+public:
+
+  MOZ_MUST_USE
+  bool EnsureLengthAtLeast(size_type aMinLen, const mozilla::fallible_t&)
+  {
+    return EnsureLengthAtLeast<FallibleAlloc>(aMinLen);
+  }
+
+  // This method inserts elements into the array, constructing
+  // them using elem_type's default constructor.
+  // @param aIndex the place to insert the new elements. This must be no
+  //               greater than the current length of the array.
+  // @param aCount the number of elements to insert
+protected:
+  template<typename ActualAlloc = Alloc>
+  elem_type* InsertElementsAt(index_type aIndex, size_type aCount)
+  {
+    if (!base_type::template InsertSlotsAt<ActualAlloc>(aIndex, aCount,
+                                                        sizeof(elem_type),
+                                                        MOZ_ALIGNOF(elem_type))) {
+      return nullptr;
+    }
+
+    // Initialize the extra array elements
+    elem_type* iter = Elements() + aIndex;
+    elem_type* iend = iter + aCount;
+    for (; iter != iend; ++iter) {
+      elem_traits::Construct(iter);
+    }
+
+    return Elements() + aIndex;
+  }
+public:
+
+  MOZ_MUST_USE
+  elem_type* InsertElementsAt(index_type aIndex, size_type aCount,
+                              const mozilla::fallible_t&)
+  {
+    return InsertElementsAt<FallibleAlloc>(aIndex, aCount);
+  }
+
+  // This method inserts elements into the array, constructing them
+  // elem_type's copy constructor (or whatever one-arg constructor
+  // happens to match the Item type).
+  // @param aIndex the place to insert the new elements. This must be no
+  //               greater than the current length of the array.
+  // @param aCount the number of elements to insert.
+  // @param aItem the value to use when constructing the new elements.
+protected:
+  template<class Item, typename ActualAlloc = Alloc>
+  elem_type* InsertElementsAt(index_type aIndex, size_type aCount,
+                              const Item& aItem);
+
+public:
+
+  template<class Item>
+  MOZ_MUST_USE
+  elem_type* InsertElementsAt(index_type aIndex, size_type aCount,
+                              const Item& aItem, const mozilla::fallible_t&)
+  {
+    return InsertElementsAt<Item, FallibleAlloc>(aIndex, aCount, aItem);
+  }
+
+  // This method may be called to minimize the memory used by this array.
+  void Compact()
+  {
+    ShrinkCapacity(sizeof(elem_type), MOZ_ALIGNOF(elem_type));
+  }
+
+  //
+  // Sorting
+  //
+
+  // This function is meant to be used with the NS_QuickSort function.  It
+  // maps the callback API expected by NS_QuickSort to the Comparator API
+  // used by nsTArray_Impl.  See nsTArray_Impl::Sort.
+  template<class Comparator>
+  static int Compare(const void* aE1, const void* aE2, void* aData)
+  {
+    const Comparator* c = reinterpret_cast<const Comparator*>(aData);
+    const elem_type* a = static_cast<const elem_type*>(aE1);
+    const elem_type* b = static_cast<const elem_type*>(aE2);
+    return c->LessThan(*a, *b) ? -1 : (c->Equals(*a, *b) ? 0 : 1);
+  }
+
+  // This method sorts the elements of the array.  It uses the LessThan
+  // method defined on the given Comparator object to collate elements.
+  // @param aComp The Comparator used to collate elements.
+  template<class Comparator>
+  void Sort(const Comparator& aComp)
+  {
+    NS_QuickSort(Elements(), Length(), sizeof(elem_type),
+                 Compare<Comparator>, const_cast<Comparator*>(&aComp));
+  }
+
+  // A variation on the Sort method defined above that assumes that
+  // 'operator<' is defined for elem_type.
+  void Sort() { Sort(nsDefaultComparator<elem_type, elem_type>()); }
+
+protected:
+  using base_type::Hdr;
+  using base_type::ShrinkCapacity;
+
+  // This method invokes elem_type's destructor on a range of elements.
+  // @param aStart The index of the first element to destroy.
+  // @param aCount The number of elements to destroy.
+  void DestructRange(index_type aStart, size_type aCount)
+  {
+    elem_type* iter = Elements() + aStart;
+    elem_type *iend = iter + aCount;
+    for (; iter != iend; ++iter) {
+      elem_traits::Destruct(iter);
+    }
+  }
+
+  // This method invokes elem_type's copy-constructor on a range of elements.
+  // @param aStart  The index of the first element to construct.
+  // @param aCount  The number of elements to construct.
+  // @param aValues The array of elements to copy.
+  template<class Item>
+  void AssignRange(index_type aStart, size_type aCount, const Item* aValues)
+  {
+    AssignRangeAlgorithm<mozilla::IsPod<Item>::value,
+                         mozilla::IsSame<Item, elem_type>::value>
+                         ::implementation(Elements(), aStart, aCount, aValues);
+  }
+};
+
+template<typename E, class Alloc>
+template<class Item, typename ActualAlloc>
+auto
+nsTArray_Impl<E, Alloc>::ReplaceElementsAt(index_type aStart, size_type aCount,
+                                           const Item* aArray, size_type aArrayLen) -> elem_type*
+{
+  // Adjust memory allocation up-front to catch errors.
+  if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>(
+        Length() + aArrayLen - aCount, sizeof(elem_type)))) {
+    return nullptr;
+  }
+  DestructRange(aStart, aCount);
+  this->template ShiftData<ActualAlloc>(aStart, aCount, aArrayLen,
+                                        sizeof(elem_type),
+                                        MOZ_ALIGNOF(elem_type));
+  AssignRange(aStart, aArrayLen, aArray);
+  return Elements() + aStart;
+}
+
+template<typename E, class Alloc>
+void
+nsTArray_Impl<E, Alloc>::RemoveElementsAt(index_type aStart, size_type aCount)
+{
+  MOZ_ASSERT(aCount == 0 || aStart < Length(), "Invalid aStart index");
+  MOZ_ASSERT(aStart + aCount <= Length(), "Invalid length");
+  // Check that the previous assert didn't overflow
+  MOZ_ASSERT(aStart <= aStart + aCount, "Start index plus length overflows");
+  DestructRange(aStart, aCount);
+  this->template ShiftData<InfallibleAlloc>(aStart, aCount, 0,
+                                            sizeof(elem_type),
+                                            MOZ_ALIGNOF(elem_type));
+}
+
+template<typename E, class Alloc>
+template<typename Predicate>
+void
+nsTArray_Impl<E, Alloc>::RemoveElementsBy(Predicate aPredicate)
+{
+  if (base_type::mHdr == EmptyHdr()) {
+    return;
+  }
+
+  index_type j = 0;
+  index_type len = Length();
+  for (index_type i = 0; i < len; ++i) {
+    if (aPredicate(Elements()[i])) {
+      elem_traits::Destruct(Elements() + i);
+    } else {
+      if (j < i) {
+        copy_type::MoveNonOverlappingRegion(Elements() + j, Elements() + i,
+                                            1, sizeof(elem_type));
+      }
+      ++j;
+    }
+  }
+  base_type::mHdr->mLength = j;
+}
+
+template<typename E, class Alloc>
+template<class Item, typename ActualAlloc>
+auto
+nsTArray_Impl<E, Alloc>::InsertElementsAt(index_type aIndex, size_type aCount,
+                                          const Item& aItem) -> elem_type*
+{
+  if (!base_type::template InsertSlotsAt<ActualAlloc>(aIndex, aCount,
+                                                      sizeof(elem_type),
+                                                      MOZ_ALIGNOF(elem_type))) {
+    return nullptr;
+  }
+
+  // Initialize the extra array elements
+  elem_type* iter = Elements() + aIndex;
+  elem_type* iend = iter + aCount;
+  for (; iter != iend; ++iter) {
+    elem_traits::Construct(iter, aItem);
+  }
+
+  return Elements() + aIndex;
+}
+
+template<typename E, class Alloc>
+template<typename ActualAlloc>
+auto
+nsTArray_Impl<E, Alloc>::InsertElementAt(index_type aIndex) -> elem_type*
+{
+  if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>(
+        Length() + 1, sizeof(elem_type)))) {
+    return nullptr;
+  }
+  this->template ShiftData<ActualAlloc>(aIndex, 0, 1, sizeof(elem_type),
+                                        MOZ_ALIGNOF(elem_type));
+  elem_type* elem = Elements() + aIndex;
+  elem_traits::Construct(elem);
+  return elem;
+}
+
+template<typename E, class Alloc>
+template<class Item, typename ActualAlloc>
+auto
+nsTArray_Impl<E, Alloc>::InsertElementAt(index_type aIndex, Item&& aItem) -> elem_type*
+{
+  if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>(
+         Length() + 1, sizeof(elem_type)))) {
+    return nullptr;
+  }
+  this->template ShiftData<ActualAlloc>(aIndex, 0, 1, sizeof(elem_type),
+                                        MOZ_ALIGNOF(elem_type));
+  elem_type* elem = Elements() + aIndex;
+  elem_traits::Construct(elem, mozilla::Forward<Item>(aItem));
+  return elem;
+}
+
+template<typename E, class Alloc>
+template<class Item, typename ActualAlloc>
+auto
+nsTArray_Impl<E, Alloc>::AppendElements(const Item* aArray, size_type aArrayLen) -> elem_type*
+{
+  if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>(
+        Length() + aArrayLen, sizeof(elem_type)))) {
+    return nullptr;
+  }
+  index_type len = Length();
+  AssignRange(len, aArrayLen, aArray);
+  this->IncrementLength(aArrayLen);
+  return Elements() + len;
+}
+
+template<typename E, class Alloc>
+template<class Item, class Allocator, typename ActualAlloc>
+auto
+nsTArray_Impl<E, Alloc>::AppendElements(nsTArray_Impl<Item, Allocator>&& aArray) -> elem_type*
+{
+  MOZ_ASSERT(&aArray != this, "argument must be different aArray");
+  if (Length() == 0) {
+    SwapElements<ActualAlloc>(aArray);
+    return Elements();
+  }
+
+  index_type len = Length();
+  index_type otherLen = aArray.Length();
+  if (!Alloc::Successful(this->template EnsureCapacity<Alloc>(
+        len + otherLen, sizeof(elem_type)))) {
+    return nullptr;
+  }
+  copy_type::MoveNonOverlappingRegion(Elements() + len, aArray.Elements(), otherLen,
+                                      sizeof(elem_type));
+  this->IncrementLength(otherLen);
+  aArray.template ShiftData<Alloc>(0, otherLen, 0, sizeof(elem_type),
+                                   MOZ_ALIGNOF(elem_type));
+  return Elements() + len;
+}
+
+template<typename E, class Alloc>
+template<class Item, typename ActualAlloc>
+auto
+nsTArray_Impl<E, Alloc>::AppendElement(Item&& aItem) -> elem_type*
+{
+  if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>(
+         Length() + 1, sizeof(elem_type)))) {
+    return nullptr;
+  }
+  elem_type* elem = Elements() + Length();
+  elem_traits::Construct(elem, mozilla::Forward<Item>(aItem));
+  this->IncrementLength(1);
+  return elem;
+}
+
+template<typename E, typename Alloc>
+inline void
+ImplCycleCollectionUnlink(nsTArray_Impl<E, Alloc>& aField)
+{
+  aField.Clear();
+}
+
+template<typename E, typename Alloc>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            nsTArray_Impl<E, Alloc>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  aFlags |= CycleCollectionEdgeNameArrayFlag;
+  size_t length = aField.Length();
+  for (size_t i = 0; i < length; ++i) {
+    ImplCycleCollectionTraverse(aCallback, aField[i], aName, aFlags);
+  }
+}
+
+//
+// nsTArray is an infallible vector class.  See the comment at the top of this
+// file for more details.
+//
+template<class E>
+class nsTArray : public nsTArray_Impl<E, nsTArrayInfallibleAllocator>
+{
+public:
+  typedef nsTArray_Impl<E, nsTArrayInfallibleAllocator> base_type;
+  typedef nsTArray<E>                                   self_type;
+  typedef typename base_type::size_type                 size_type;
+
+  nsTArray() {}
+  explicit nsTArray(size_type aCapacity) : base_type(aCapacity) {}
+  explicit nsTArray(const nsTArray& aOther) : base_type(aOther) {}
+  MOZ_IMPLICIT nsTArray(nsTArray&& aOther) : base_type(mozilla::Move(aOther)) {}
+  MOZ_IMPLICIT nsTArray(std::initializer_list<E> aIL) : base_type(aIL) {}
+
+  template<class Allocator>
+  explicit nsTArray(const nsTArray_Impl<E, Allocator>& aOther)
+    : base_type(aOther)
+  {
+  }
+  template<class Allocator>
+  MOZ_IMPLICIT nsTArray(nsTArray_Impl<E, Allocator>&& aOther)
+    : base_type(mozilla::Move(aOther))
+  {
+  }
+
+  self_type& operator=(const self_type& aOther)
+  {
+    base_type::operator=(aOther);
+    return *this;
+  }
+  template<class Allocator>
+  self_type& operator=(const nsTArray_Impl<E, Allocator>& aOther)
+  {
+    base_type::operator=(aOther);
+    return *this;
+  }
+  self_type& operator=(self_type&& aOther)
+  {
+    base_type::operator=(mozilla::Move(aOther));
+    return *this;
+  }
+  template<class Allocator>
+  self_type& operator=(nsTArray_Impl<E, Allocator>&& aOther)
+  {
+    base_type::operator=(mozilla::Move(aOther));
+    return *this;
+  }
+
+  using base_type::AppendElement;
+  using base_type::AppendElements;
+  using base_type::EnsureLengthAtLeast;
+  using base_type::InsertElementAt;
+  using base_type::InsertElementsAt;
+  using base_type::InsertElementSorted;
+  using base_type::ReplaceElementsAt;
+  using base_type::SetCapacity;
+  using base_type::SetLength;
+};
+
+//
+// FallibleTArray is a fallible vector class.
+//
+template<class E>
+class FallibleTArray : public nsTArray_Impl<E, nsTArrayFallibleAllocator>
+{
+public:
+  typedef nsTArray_Impl<E, nsTArrayFallibleAllocator>   base_type;
+  typedef FallibleTArray<E>                             self_type;
+  typedef typename base_type::size_type                 size_type;
+
+  FallibleTArray() {}
+  explicit FallibleTArray(size_type aCapacity) : base_type(aCapacity) {}
+  explicit FallibleTArray(const FallibleTArray<E>& aOther) : base_type(aOther) {}
+  FallibleTArray(FallibleTArray<E>&& aOther)
+    : base_type(mozilla::Move(aOther))
+  {
+  }
+
+  template<class Allocator>
+  explicit FallibleTArray(const nsTArray_Impl<E, Allocator>& aOther)
+    : base_type(aOther)
+  {
+  }
+  template<class Allocator>
+  explicit FallibleTArray(nsTArray_Impl<E, Allocator>&& aOther)
+    : base_type(mozilla::Move(aOther))
+  {
+  }
+
+  self_type& operator=(const self_type& aOther)
+  {
+    base_type::operator=(aOther);
+    return *this;
+  }
+  template<class Allocator>
+  self_type& operator=(const nsTArray_Impl<E, Allocator>& aOther)
+  {
+    base_type::operator=(aOther);
+    return *this;
+  }
+  self_type& operator=(self_type&& aOther)
+  {
+    base_type::operator=(mozilla::Move(aOther));
+    return *this;
+  }
+  template<class Allocator>
+  self_type& operator=(nsTArray_Impl<E, Allocator>&& aOther)
+  {
+    base_type::operator=(mozilla::Move(aOther));
+    return *this;
+  }
+};
+
+//
+// AutoTArray<E, N> is like nsTArray<E>, but with N elements of inline storage.
+// Storing more than N elements is fine, but it will cause a heap allocation.
+//
+template<class E, size_t N>
+class MOZ_NON_MEMMOVABLE AutoTArray : public nsTArray<E>
+{
+  static_assert(N != 0, "AutoTArray<E, 0> should be specialized");
+public:
+  typedef AutoTArray<E, N> self_type;
+  typedef nsTArray<E> base_type;
+  typedef typename base_type::Header Header;
+  typedef typename base_type::elem_type elem_type;
+
+  AutoTArray()
+  {
+    Init();
+  }
+
+  AutoTArray(const self_type& aOther)
+  {
+    Init();
+    this->AppendElements(aOther);
+  }
+
+  explicit AutoTArray(const base_type& aOther)
+  {
+    Init();
+    this->AppendElements(aOther);
+  }
+
+  explicit AutoTArray(base_type&& aOther)
+  {
+    Init();
+    this->SwapElements(aOther);
+  }
+
+  template<typename Allocator>
+  explicit AutoTArray(nsTArray_Impl<elem_type, Allocator>&& aOther)
+  {
+    Init();
+    this->SwapElements(aOther);
+  }
+
+  MOZ_IMPLICIT AutoTArray(std::initializer_list<E> aIL)
+  {
+    Init();
+    this->AppendElements(aIL.begin(), aIL.size());
+  }
+
+  self_type& operator=(const self_type& aOther)
+  {
+    base_type::operator=(aOther);
+    return *this;
+  }
+
+  template<typename Allocator>
+  self_type& operator=(const nsTArray_Impl<elem_type, Allocator>& aOther)
+  {
+    base_type::operator=(aOther);
+    return *this;
+  }
+
+private:
+  // nsTArray_base casts itself as an nsAutoArrayBase in order to get a pointer
+  // to mAutoBuf.
+  template<class Allocator, class Copier>
+  friend class nsTArray_base;
+
+  void Init()
+  {
+    static_assert(MOZ_ALIGNOF(elem_type) <= 8,
+                  "can't handle alignments greater than 8, "
+                  "see nsTArray_base::UsesAutoArrayBuffer()");
+    // Temporary work around for VS2012 RC compiler crash
+    Header** phdr = base_type::PtrToHdr();
+    *phdr = reinterpret_cast<Header*>(&mAutoBuf);
+    (*phdr)->mLength = 0;
+    (*phdr)->mCapacity = N;
+    (*phdr)->mIsAutoArray = 1;
+
+    MOZ_ASSERT(base_type::GetAutoArrayBuffer(MOZ_ALIGNOF(elem_type)) ==
+               reinterpret_cast<Header*>(&mAutoBuf),
+               "GetAutoArrayBuffer needs to be fixed");
+  }
+
+  // Declare mAutoBuf aligned to the maximum of the header's alignment and
+  // elem_type's alignment.  We need to use a union rather than
+  // MOZ_ALIGNED_DECL because GCC is picky about what goes into
+  // __attribute__((aligned(foo))).
+  union
+  {
+    char mAutoBuf[sizeof(nsTArrayHeader) + N * sizeof(elem_type)];
+    // Do the max operation inline to ensure that it is a compile-time constant.
+    mozilla::AlignedElem<(MOZ_ALIGNOF(Header) > MOZ_ALIGNOF(elem_type)) ?
+                         MOZ_ALIGNOF(Header) : MOZ_ALIGNOF(elem_type)> mAlign;
+  };
+};
+
+//
+// Specialization of AutoTArray<E, N> for the case where N == 0.
+// AutoTArray<E, 0> behaves exactly like nsTArray<E>, but without this
+// specialization, it stores a useless inline header.
+//
+// We do have many AutoTArray<E, 0> objects in memory: about 2,000 per tab as
+// of May 2014. These are typically not explicitly AutoTArray<E, 0> but rather
+// AutoTArray<E, N> for some value N depending on template parameters, in
+// generic code.
+//
+// For that reason, we optimize this case with the below partial specialization,
+// which ensures that AutoTArray<E, 0> is just like nsTArray<E>, without any
+// inline header overhead.
+//
+template<class E>
+class AutoTArray<E, 0> : public nsTArray<E>
+{
+};
+
+template<class E, size_t N>
+struct nsTArray_CopyChooser<AutoTArray<E, N>>
+{
+  typedef nsTArray_CopyWithConstructors<AutoTArray<E, N>> Type;
+};
+
+// Assert that AutoTArray doesn't have any extra padding inside.
+//
+// It's important that the data stored in this auto array takes up a multiple of
+// 8 bytes; e.g. AutoTArray<uint32_t, 1> wouldn't work.  Since AutoTArray
+// contains a pointer, its size must be a multiple of alignof(void*).  (This is
+// because any type may be placed into an array, and there's no padding between
+// elements of an array.)  The compiler pads the end of the structure to
+// enforce this rule.
+//
+// If we used AutoTArray<uint32_t, 1> below, this assertion would fail on a
+// 64-bit system, where the compiler inserts 4 bytes of padding at the end of
+// the auto array to make its size a multiple of alignof(void*) == 8 bytes.
+
+static_assert(sizeof(AutoTArray<uint32_t, 2>) ==
+              sizeof(void*) + sizeof(nsTArrayHeader) + sizeof(uint32_t) * 2,
+              "AutoTArray shouldn't contain any extra padding, "
+              "see the comment");
+
+// Definitions of nsTArray_Impl methods
+#include "nsTArray-inl.h"
+
+#endif  // nsTArray_h__
diff --git a/xpcom/glue/nsTArrayForwardDeclare.h b/xpcom/glue/nsTArrayForwardDeclare.h
new file mode 100644
index 000000000..f63ef5f59
--- /dev/null
+++ b/xpcom/glue/nsTArrayForwardDeclare.h
@@ -0,0 +1,36 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTArrayForwardDeclare_h__
+#define nsTArrayForwardDeclare_h__
+
+//
+// This simple header file contains forward declarations for the TArray family
+// of classes.
+//
+// Including this header is preferable to writing
+//
+//   template<class E> class nsTArray;
+//
+// yourself, since this header gives us flexibility to e.g. change the default
+// template parameters.
+//
+
+#include <stddef.h>
+
+template<class E>
+class nsTArray;
+
+template<class E>
+class FallibleTArray;
+
+template<class E, size_t N>
+class AutoTArray;
+
+template<class E>
+using InfallibleTArray = nsTArray<E>;
+
+#endif
diff --git a/xpcom/glue/nsTHashtable.h b/xpcom/glue/nsTHashtable.h
new file mode 100644
index 000000000..705b0294e
--- /dev/null
+++ b/xpcom/glue/nsTHashtable.h
@@ -0,0 +1,577 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTHashtable_h__
+#define nsTHashtable_h__
+
+#include "PLDHashTable.h"
+#include "nsPointerHashKeys.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/fallible.h"
+#include "mozilla/MemoryChecking.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Move.h"
+#include "mozilla/OperatorNewExtensions.h"
+#include "mozilla/PodOperations.h"
+#include "mozilla/TypeTraits.h"
+
+#include <new>
+
+/**
+ * a base class for templated hashtables.
+ *
+ * Clients will rarely need to use this class directly. Check the derived
+ * classes first, to see if they will meet your needs.
+ *
+ * @param EntryType  the templated entry-type class that is managed by the
+ *   hashtable. <code>EntryType</code> must extend the following declaration,
+ *   and <strong>must not declare any virtual functions or derive from classes
+ *   with virtual functions.</strong>  Any vtable pointer would break the
+ *   PLDHashTable code.
+ *<pre>   class EntryType : public PLDHashEntryHdr
+ *   {
+ *   public: or friend nsTHashtable<EntryType>;
+ *     // KeyType is what we use when Get()ing or Put()ing this entry
+ *     // this should either be a simple datatype (uint32_t, nsISupports*) or
+ *     // a const reference (const nsAString&)
+ *     typedef something KeyType;
+ *     // KeyTypePointer is the pointer-version of KeyType, because
+ *     // PLDHashTable.h requires keys to cast to <code>const void*</code>
+ *     typedef const something* KeyTypePointer;
+ *
+ *     EntryType(KeyTypePointer aKey);
+ *
+ *     // A copy or C++11 Move constructor must be defined, even if
+ *     // AllowMemMove() == true, otherwise you will cause link errors.
+ *     EntryType(const EntryType& aEnt);  // Either this...
+ *     EntryType(EntryType&& aEnt);       // ...or this
+ *
+ *     // the destructor must be defined... or you will cause link errors!
+ *     ~EntryType();
+ *
+ *     // KeyEquals(): does this entry match this key?
+ *     bool KeyEquals(KeyTypePointer aKey) const;
+ *
+ *     // KeyToPointer(): Convert KeyType to KeyTypePointer
+ *     static KeyTypePointer KeyToPointer(KeyType aKey);
+ *
+ *     // HashKey(): calculate the hash number
+ *     static PLDHashNumber HashKey(KeyTypePointer aKey);
+ *
+ *     // ALLOW_MEMMOVE can we move this class with memmove(), or do we have
+ *     // to use the copy constructor?
+ *     enum { ALLOW_MEMMOVE = true/false };
+ *   }</pre>
+ *
+ * @see nsInterfaceHashtable
+ * @see nsDataHashtable
+ * @see nsClassHashtable
+ * @author "Benjamin Smedberg <bsmedberg@covad.net>"
+ */
+
+template<class EntryType>
+class MOZ_NEEDS_NO_VTABLE_TYPE nsTHashtable
+{
+  typedef mozilla::fallible_t fallible_t;
+  static_assert(mozilla::IsPointer<typename EntryType::KeyTypePointer>::value,
+                "KeyTypePointer should be a pointer");
+
+public:
+  // Separate constructors instead of default aInitLength parameter since
+  // otherwise the default no-arg constructor isn't found.
+  nsTHashtable()
+    : mTable(Ops(), sizeof(EntryType), PLDHashTable::kDefaultInitialLength)
+  {}
+  explicit nsTHashtable(uint32_t aInitLength)
+    : mTable(Ops(), sizeof(EntryType), aInitLength)
+  {}
+
+  /**
+   * destructor, cleans up and deallocates
+   */
+  ~nsTHashtable();
+
+  nsTHashtable(nsTHashtable<EntryType>&& aOther);
+
+  /**
+   * Return the generation number for the table. This increments whenever
+   * the table data items are moved.
+   */
+  uint32_t GetGeneration() const { return mTable.Generation(); }
+
+  /**
+   * KeyType is typedef'ed for ease of use.
+   */
+  typedef typename EntryType::KeyType KeyType;
+
+  /**
+   * KeyTypePointer is typedef'ed for ease of use.
+   */
+  typedef typename EntryType::KeyTypePointer KeyTypePointer;
+
+  /**
+   * Return the number of entries in the table.
+   * @return    number of entries
+   */
+  uint32_t Count() const { return mTable.EntryCount(); }
+
+  /**
+   * Return true if the hashtable is empty.
+   */
+  bool IsEmpty() const { return Count() == 0; }
+
+  /**
+   * Get the entry associated with a key.
+   * @param     aKey the key to retrieve
+   * @return    pointer to the entry class, if the key exists; nullptr if the
+   *            key doesn't exist
+   */
+  EntryType* GetEntry(KeyType aKey) const
+  {
+    return static_cast<EntryType*>(
+      const_cast<PLDHashTable*>(&mTable)->Search(EntryType::KeyToPointer(aKey)));
+  }
+
+  /**
+   * Return true if an entry for the given key exists, false otherwise.
+   * @param     aKey the key to retrieve
+   * @return    true if the key exists, false if the key doesn't exist
+   */
+  bool Contains(KeyType aKey) const { return !!GetEntry(aKey); }
+
+  /**
+   * Get the entry associated with a key, or create a new entry,
+   * @param     aKey the key to retrieve
+   * @return    pointer to the entry class retreived; nullptr only if memory
+                can't be allocated
+   */
+  EntryType* PutEntry(KeyType aKey)
+  {
+    // infallible add
+    return static_cast<EntryType*>(mTable.Add(EntryType::KeyToPointer(aKey)));
+  }
+
+  MOZ_MUST_USE
+  EntryType* PutEntry(KeyType aKey, const fallible_t&)
+  {
+    return static_cast<EntryType*>(mTable.Add(EntryType::KeyToPointer(aKey),
+                                              mozilla::fallible));
+  }
+
+  /**
+   * Remove the entry associated with a key.
+   * @param     aKey of the entry to remove
+   */
+  void RemoveEntry(KeyType aKey)
+  {
+    mTable.Remove(EntryType::KeyToPointer(aKey));
+  }
+
+  /**
+   * Remove the entry associated with a key.
+   * @param aEntry   the entry-pointer to remove (obtained from GetEntry)
+   */
+  void RemoveEntry(EntryType* aEntry)
+  {
+    mTable.RemoveEntry(aEntry);
+  }
+
+  /**
+   * Remove the entry associated with a key, but don't resize the hashtable.
+   * This is a low-level method, and is not recommended unless you know what
+   * you're doing. If you use it, please add a comment explaining why you
+   * didn't use RemoveEntry().
+   * @param aEntry   the entry-pointer to remove (obtained from GetEntry)
+   */
+  void RawRemoveEntry(EntryType* aEntry)
+  {
+    mTable.RawRemove(aEntry);
+  }
+
+  // This is an iterator that also allows entry removal. Example usage:
+  //
+  //   for (auto iter = table.Iter(); !iter.Done(); iter.Next()) {
+  //     Entry* entry = iter.Get();
+  //     // ... do stuff with |entry| ...
+  //     // ... possibly call iter.Remove() once ...
+  //   }
+  //
+  class Iterator : public PLDHashTable::Iterator
+  {
+  public:
+    typedef PLDHashTable::Iterator Base;
+
+    explicit Iterator(nsTHashtable* aTable) : Base(&aTable->mTable) {}
+    Iterator(Iterator&& aOther) : Base(aOther.mTable) {}
+    ~Iterator() {}
+
+    EntryType* Get() const { return static_cast<EntryType*>(Base::Get()); }
+
+  private:
+    Iterator() = delete;
+    Iterator(const Iterator&) = delete;
+    Iterator& operator=(const Iterator&) = delete;
+    Iterator& operator=(const Iterator&&) = delete;
+  };
+
+  Iterator Iter() { return Iterator(this); }
+
+  Iterator ConstIter() const
+  {
+    return Iterator(const_cast<nsTHashtable*>(this));
+  }
+
+  /**
+   * Remove all entries, return hashtable to "pristine" state. It's
+   * conceptually the same as calling the destructor and then re-calling the
+   * constructor.
+   */
+  void Clear()
+  {
+    mTable.Clear();
+  }
+
+  /**
+   * Measure the size of the table's entry storage. Does *not* measure anything
+   * hanging off table entries; hence the "Shallow" prefix. To measure that,
+   * either use SizeOfExcludingThis() or iterate manually over the entries,
+   * calling SizeOfExcludingThis() on each one.
+   *
+   * @param     aMallocSizeOf the function used to measure heap-allocated blocks
+   * @return    the measured shallow size of the table
+   */
+  size_t ShallowSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return mTable.ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  /**
+   * Like ShallowSizeOfExcludingThis, but includes sizeof(*this).
+   */
+  size_t ShallowSizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return aMallocSizeOf(this) + ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  /**
+   * This is a "deep" measurement of the table. To use it, |EntryType| must
+   * define SizeOfExcludingThis, and that method will be called on all live
+   * entries.
+   */
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    size_t n = ShallowSizeOfExcludingThis(aMallocSizeOf);
+    for (auto iter = ConstIter(); !iter.Done(); iter.Next()) {
+      n += (*iter.Get()).SizeOfExcludingThis(aMallocSizeOf);
+    }
+    return n;
+  }
+
+  /**
+   * Like SizeOfExcludingThis, but includes sizeof(*this).
+   */
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  /**
+   * Swap the elements in this hashtable with the elements in aOther.
+   */
+  void SwapElements(nsTHashtable<EntryType>& aOther)
+  {
+    MOZ_ASSERT_IF(this->mTable.Ops() && aOther.mTable.Ops(),
+                  this->mTable.Ops() == aOther.mTable.Ops());
+    mozilla::Swap(this->mTable, aOther.mTable);
+  }
+
+#ifdef DEBUG
+  /**
+   * Mark the table as constant after initialization.
+   *
+   * This will prevent assertions when a read-only hash is accessed on multiple
+   * threads without synchronization.
+   */
+  void MarkImmutable()
+  {
+    mTable.MarkImmutable();
+  }
+#endif
+
+protected:
+  PLDHashTable mTable;
+
+  static PLDHashNumber s_HashKey(const void* aKey);
+
+  static bool s_MatchEntry(const PLDHashEntryHdr* aEntry,
+                           const void* aKey);
+
+  static void s_CopyEntry(PLDHashTable* aTable, const PLDHashEntryHdr* aFrom,
+                          PLDHashEntryHdr* aTo);
+
+  static void s_ClearEntry(PLDHashTable* aTable, PLDHashEntryHdr* aEntry);
+
+  static void s_InitEntry(PLDHashEntryHdr* aEntry, const void* aKey);
+
+private:
+  // copy constructor, not implemented
+  nsTHashtable(nsTHashtable<EntryType>& aToCopy) = delete;
+
+  /**
+   * Gets the table's ops.
+   */
+  static const PLDHashTableOps* Ops();
+
+  // assignment operator, not implemented
+  nsTHashtable<EntryType>& operator=(nsTHashtable<EntryType>& aToEqual) = delete;
+};
+
+//
+// template definitions
+//
+
+template<class EntryType>
+nsTHashtable<EntryType>::nsTHashtable(nsTHashtable<EntryType>&& aOther)
+  : mTable(mozilla::Move(aOther.mTable))
+{
+  // aOther shouldn't touch mTable after this, because we've stolen the table's
+  // pointers but not overwitten them.
+  MOZ_MAKE_MEM_UNDEFINED(&aOther.mTable, sizeof(aOther.mTable));
+}
+
+template<class EntryType>
+nsTHashtable<EntryType>::~nsTHashtable()
+{
+}
+
+template<class EntryType>
+/* static */ const PLDHashTableOps*
+nsTHashtable<EntryType>::Ops()
+{
+  // If this variable is a global variable, we get strange start-up failures on
+  // WindowsCrtPatch.h (see bug 1166598 comment 20). But putting it inside a
+  // function avoids that problem.
+  static const PLDHashTableOps sOps =
+  {
+    s_HashKey,
+    s_MatchEntry,
+    EntryType::ALLOW_MEMMOVE ? PLDHashTable::MoveEntryStub : s_CopyEntry,
+    s_ClearEntry,
+    s_InitEntry
+  };
+  return &sOps;
+}
+
+// static definitions
+
+template<class EntryType>
+PLDHashNumber
+nsTHashtable<EntryType>::s_HashKey(const void* aKey)
+{
+  return EntryType::HashKey(static_cast<const KeyTypePointer>(aKey));
+}
+
+template<class EntryType>
+bool
+nsTHashtable<EntryType>::s_MatchEntry(const PLDHashEntryHdr* aEntry,
+                                      const void* aKey)
+{
+  return ((const EntryType*)aEntry)->KeyEquals(
+    static_cast<const KeyTypePointer>(aKey));
+}
+
+template<class EntryType>
+void
+nsTHashtable<EntryType>::s_CopyEntry(PLDHashTable* aTable,
+                                     const PLDHashEntryHdr* aFrom,
+                                     PLDHashEntryHdr* aTo)
+{
+  EntryType* fromEntry =
+    const_cast<EntryType*>(static_cast<const EntryType*>(aFrom));
+
+  new (mozilla::KnownNotNull, aTo) EntryType(mozilla::Move(*fromEntry));
+
+  fromEntry->~EntryType();
+}
+
+template<class EntryType>
+void
+nsTHashtable<EntryType>::s_ClearEntry(PLDHashTable* aTable,
+                                      PLDHashEntryHdr* aEntry)
+{
+  static_cast<EntryType*>(aEntry)->~EntryType();
+}
+
+template<class EntryType>
+void
+nsTHashtable<EntryType>::s_InitEntry(PLDHashEntryHdr* aEntry,
+                                     const void* aKey)
+{
+  new (mozilla::KnownNotNull, aEntry) EntryType(static_cast<KeyTypePointer>(aKey));
+}
+
+class nsCycleCollectionTraversalCallback;
+
+template<class EntryType>
+inline void
+ImplCycleCollectionUnlink(nsTHashtable<EntryType>& aField)
+{
+  aField.Clear();
+}
+
+template<class EntryType>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            nsTHashtable<EntryType>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  for (auto iter = aField.Iter(); !iter.Done(); iter.Next()) {
+    EntryType* entry = iter.Get();
+    ImplCycleCollectionTraverse(aCallback, *entry, aName, aFlags);
+  }
+}
+
+/**
+ * For nsTHashtable with pointer entries, we can have a template specialization
+ * that layers a typed T* interface on top of a common implementation that
+ * works internally with void pointers.  This arrangement saves code size and
+ * might slightly improve performance as well.
+ */
+
+/**
+ * We need a separate entry type class for the inheritance structure of the
+ * nsTHashtable specialization below; nsVoidPtrHashKey is simply typedefed to a
+ * specialization of nsPtrHashKey, and the formulation:
+ *
+ * class nsTHashtable<nsPtrHashKey<T>> : protected nsTHashtable<nsPtrHashKey<const void>
+ *
+ * is not going to turn out very well, since we'd wind up with an nsTHashtable
+ * instantiation that is its own base class.
+ */
+namespace detail {
+
+class VoidPtrHashKey : public nsPtrHashKey<const void>
+{
+  typedef nsPtrHashKey<const void> Base;
+
+public:
+  explicit VoidPtrHashKey(const void* aKey) : Base(aKey) {}
+};
+
+} // namespace detail
+
+/**
+ * See the main nsTHashtable documentation for descriptions of this class's
+ * methods.
+ */
+template<typename T>
+class nsTHashtable<nsPtrHashKey<T>> : protected nsTHashtable<::detail::VoidPtrHashKey>
+{
+  typedef nsTHashtable<::detail::VoidPtrHashKey> Base;
+  typedef nsPtrHashKey<T> EntryType;
+
+  // We play games with reinterpret_cast'ing between these two classes, so
+  // try to ensure that playing said games is reasonable.
+  static_assert(sizeof(nsPtrHashKey<T>) == sizeof(::detail::VoidPtrHashKey),
+                "hash keys must be the same size");
+
+  nsTHashtable(const nsTHashtable& aOther) = delete;
+  nsTHashtable& operator=(const nsTHashtable& aOther) = delete;
+
+public:
+  nsTHashtable() = default;
+  explicit nsTHashtable(uint32_t aInitLength)
+    : Base(aInitLength)
+  {}
+
+  ~nsTHashtable() = default;
+
+  nsTHashtable(nsTHashtable&&) = default;
+
+  /* Wrapper functions */
+  using Base::GetGeneration;
+  using Base::Count;
+  using Base::IsEmpty;
+  using Base::Clear;
+
+  using Base::ShallowSizeOfExcludingThis;
+  using Base::ShallowSizeOfIncludingThis;
+
+#ifdef DEBUG
+  using Base::MarkImmutable;
+#endif
+
+  EntryType* GetEntry(T* aKey) const
+  {
+    return reinterpret_cast<EntryType*>(Base::GetEntry(aKey));
+  }
+
+  bool Contains(T* aKey) const
+  {
+    return Base::Contains(aKey);
+  }
+
+  EntryType* PutEntry(T* aKey)
+  {
+    return reinterpret_cast<EntryType*>(Base::PutEntry(aKey));
+  }
+
+  MOZ_MUST_USE
+  EntryType* PutEntry(T* aKey, const mozilla::fallible_t&)
+  {
+    return reinterpret_cast<EntryType*>(
+      Base::PutEntry(aKey, mozilla::fallible));
+  }
+
+  void RemoveEntry(T* aKey)
+  {
+    Base::RemoveEntry(aKey);
+  }
+
+  void RemoveEntry(EntryType* aEntry)
+  {
+    Base::RemoveEntry(reinterpret_cast<::detail::VoidPtrHashKey*>(aEntry));
+  }
+
+  void RawRemoveEntry(EntryType* aEntry)
+  {
+    Base::RawRemoveEntry(reinterpret_cast<::detail::VoidPtrHashKey*>(aEntry));
+  }
+
+  class Iterator : public Base::Iterator
+  {
+  public:
+    typedef nsTHashtable::Base::Iterator Base;
+
+    explicit Iterator(nsTHashtable* aTable) : Base(aTable) {}
+    Iterator(Iterator&& aOther) : Base(mozilla::Move(aOther)) {}
+    ~Iterator() = default;
+
+    EntryType* Get() const { return reinterpret_cast<EntryType*>(Base::Get()); }
+
+  private:
+    Iterator() = delete;
+    Iterator(const Iterator&) = delete;
+    Iterator& operator=(const Iterator&) = delete;
+    Iterator& operator=(Iterator&&) = delete;
+  };
+
+  Iterator Iter() { return Iterator(this); }
+
+  Iterator ConstIter() const
+  {
+    return Iterator(const_cast<nsTHashtable*>(this));
+  }
+
+  void SwapElements(nsTHashtable& aOther)
+  {
+    Base::SwapElements(aOther);
+  }
+};
+
+#endif // nsTHashtable_h__
diff --git a/xpcom/glue/nsTObserverArray.cpp b/xpcom/glue/nsTObserverArray.cpp
new file mode 100644
index 000000000..dd68631f4
--- /dev/null
+++ b/xpcom/glue/nsTObserverArray.cpp
@@ -0,0 +1,31 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsTObserverArray.h"
+
+void
+nsTObserverArray_base::AdjustIterators(index_type aModPos,
+                                       diff_type aAdjustment)
+{
+  NS_PRECONDITION(aAdjustment == -1 || aAdjustment == 1, "invalid adjustment");
+  Iterator_base* iter = mIterators;
+  while (iter) {
+    if (iter->mPosition > aModPos) {
+      iter->mPosition += aAdjustment;
+    }
+    iter = iter->mNext;
+  }
+}
+
+void
+nsTObserverArray_base::ClearIterators()
+{
+  Iterator_base* iter = mIterators;
+  while (iter) {
+    iter->mPosition = 0;
+    iter = iter->mNext;
+  }
+}
diff --git a/xpcom/glue/nsTObserverArray.h b/xpcom/glue/nsTObserverArray.h
new file mode 100644
index 000000000..e9966d080
--- /dev/null
+++ b/xpcom/glue/nsTObserverArray.h
@@ -0,0 +1,520 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTObserverArray_h___
+#define nsTObserverArray_h___
+
+#include "mozilla/MemoryReporting.h"
+#include "nsTArray.h"
+#include "nsCycleCollectionNoteChild.h"
+
+/**
+ * An array of observers. Like a normal array, but supports iterators that are
+ * stable even if the array is modified during iteration.
+ * The template parameter T is the observer type the array will hold;
+ * N is the number of built-in storage slots that come with the array.
+ * NOTE: You probably want to use nsTObserverArray, unless you specifically
+ * want built-in storage. See below.
+ * @see nsTObserverArray, nsTArray
+ */
+
+class nsTObserverArray_base
+{
+public:
+  typedef size_t index_type;
+  typedef size_t size_type;
+  typedef ptrdiff_t diff_type;
+
+protected:
+  class Iterator_base
+  {
+  protected:
+    friend class nsTObserverArray_base;
+
+    Iterator_base(index_type aPosition, Iterator_base* aNext)
+      : mPosition(aPosition)
+      , mNext(aNext)
+    {
+    }
+
+    // The current position of the iterator. Its exact meaning differs
+    // depending on iterator. See nsTObserverArray<T>::ForwardIterator.
+    index_type mPosition;
+
+    // The next iterator currently iterating the same array
+    Iterator_base* mNext;
+  };
+
+  nsTObserverArray_base() : mIterators(nullptr) {}
+
+  ~nsTObserverArray_base()
+  {
+    NS_ASSERTION(mIterators == nullptr, "iterators outlasting array");
+  }
+
+  /**
+   * Adjusts iterators after an element has been inserted or removed
+   * from the array.
+   * @param aModPos     Position where elements were added or removed.
+   * @param aAdjustment -1 if an element was removed, 1 if an element was
+   *                    added.
+   */
+  void AdjustIterators(index_type aModPos, diff_type aAdjustment);
+
+  /**
+   * Clears iterators when the array is destroyed.
+   */
+  void ClearIterators();
+
+  mutable Iterator_base* mIterators;
+};
+
+template<class T, size_t N>
+class nsAutoTObserverArray : protected nsTObserverArray_base
+{
+public:
+  typedef T           elem_type;
+  typedef nsTArray<T> array_type;
+
+  nsAutoTObserverArray() {}
+
+  //
+  // Accessor methods
+  //
+
+  // @return The number of elements in the array.
+  size_type Length() const { return mArray.Length(); }
+
+  // @return True if the array is empty or false otherwise.
+  bool IsEmpty() const { return mArray.IsEmpty(); }
+
+  // This method provides direct access to an element of the array. The given
+  // index must be within the array bounds. If the underlying array may change
+  // during iteration, use an iterator instead of this function.
+  // @param aIndex The index of an element in the array.
+  // @return A reference to the i'th element of the array.
+  elem_type& ElementAt(index_type aIndex)
+  {
+    return mArray.ElementAt(aIndex);
+  }
+
+  // Same as above, but readonly.
+  const elem_type& ElementAt(index_type aIndex) const
+  {
+    return mArray.ElementAt(aIndex);
+  }
+
+  // This method provides direct access to an element of the array in a bounds
+  // safe manner. If the requested index is out of bounds the provided default
+  // value is returned.
+  // @param aIndex The index of an element in the array.
+  // @param aDef   The value to return if the index is out of bounds.
+  elem_type& SafeElementAt(index_type aIndex, elem_type& aDef)
+  {
+    return mArray.SafeElementAt(aIndex, aDef);
+  }
+
+  // Same as above, but readonly.
+  const elem_type& SafeElementAt(index_type aIndex, const elem_type& aDef) const
+  {
+    return mArray.SafeElementAt(aIndex, aDef);
+  }
+
+  // No operator[] is provided because the point of this class is to support
+  // allow modifying the array during iteration, and ElementAt() is not safe
+  // in those conditions.
+
+  //
+  // Search methods
+  //
+
+  // This method searches, starting from the beginning of the array,
+  // for the first element in this array that is equal to the given element.
+  // 'operator==' must be defined for elem_type.
+  // @param aItem The item to search for.
+  // @return      true if the element was found.
+  template<class Item>
+  bool Contains(const Item& aItem) const
+  {
+    return IndexOf(aItem) != array_type::NoIndex;
+  }
+
+  // This method searches for the offset of the first element in this
+  // array that is equal to the given element.
+  // 'operator==' must be defined for elem_type.
+  // @param aItem  The item to search for.
+  // @param aStart The index to start from.
+  // @return The index of the found element or NoIndex if not found.
+  template<class Item>
+  index_type IndexOf(const Item& aItem, index_type aStart = 0) const
+  {
+    return mArray.IndexOf(aItem, aStart);
+  }
+
+  //
+  // Mutation methods
+  //
+
+  // Insert a given element at the given index.
+  // @param aIndex The index at which to insert item.
+  // @param aItem  The item to insert,
+  // @return A pointer to the newly inserted element, or a null on DOM
+  template<class Item>
+  elem_type* InsertElementAt(index_type aIndex, const Item& aItem)
+  {
+    elem_type* item = mArray.InsertElementAt(aIndex, aItem);
+    AdjustIterators(aIndex, 1);
+    return item;
+  }
+
+  // Same as above but without copy constructing.
+  // This is useful to avoid temporaries.
+  elem_type* InsertElementAt(index_type aIndex)
+  {
+    elem_type* item = mArray.InsertElementAt(aIndex);
+    AdjustIterators(aIndex, 1);
+    return item;
+  }
+
+  // Prepend an element to the array unless it already exists in the array.
+  // 'operator==' must be defined for elem_type.
+  // @param aItem The item to prepend.
+  // @return true if the element was found, or inserted successfully.
+  template<class Item>
+  bool PrependElementUnlessExists(const Item& aItem)
+  {
+    if (Contains(aItem)) {
+      return true;
+    }
+
+    bool inserted = mArray.InsertElementAt(0, aItem) != nullptr;
+    AdjustIterators(0, 1);
+    return inserted;
+  }
+
+  // Append an element to the array.
+  // @param aItem The item to append.
+  // @return A pointer to the newly appended element, or null on OOM.
+  template<class Item>
+  elem_type* AppendElement(const Item& aItem)
+  {
+    return mArray.AppendElement(aItem);
+  }
+
+  // Same as above, but without copy-constructing. This is useful to avoid
+  // temporaries.
+  elem_type* AppendElement()
+  {
+    return mArray.AppendElement();
+  }
+
+  // Append an element to the array unless it already exists in the array.
+  // 'operator==' must be defined for elem_type.
+  // @param aItem The item to append.
+  // @return true if the element was found, or inserted successfully.
+  template<class Item>
+  bool AppendElementUnlessExists(const Item& aItem)
+  {
+    return Contains(aItem) || AppendElement(aItem) != nullptr;
+  }
+
+  // Remove an element from the array.
+  // @param aIndex The index of the item to remove.
+  void RemoveElementAt(index_type aIndex)
+  {
+    NS_ASSERTION(aIndex < mArray.Length(), "invalid index");
+    mArray.RemoveElementAt(aIndex);
+    AdjustIterators(aIndex, -1);
+  }
+
+  // This helper function combines IndexOf with RemoveElementAt to "search
+  // and destroy" the first element that is equal to the given element.
+  // 'operator==' must be defined for elem_type.
+  // @param aItem The item to search for.
+  // @return true if the element was found and removed.
+  template<class Item>
+  bool RemoveElement(const Item& aItem)
+  {
+    index_type index = mArray.IndexOf(aItem, 0);
+    if (index == array_type::NoIndex) {
+      return false;
+    }
+
+    mArray.RemoveElementAt(index);
+    AdjustIterators(index, -1);
+    return true;
+  }
+
+  // See nsTArray::RemoveElementsBy.
+  void RemoveElementsBy(mozilla::function<bool(const elem_type&)> aPredicate)
+  {
+    index_type i = 0;
+    mArray.RemoveElementsBy([&](const elem_type& aItem) {
+      if (aPredicate(aItem)) {
+        // This element is going to be removed.
+        AdjustIterators(i, -1);
+        return true;
+      }
+      ++i;
+      return false;
+    });
+  }
+
+  // Removes all observers and collapses all iterators to the beginning of
+  // the array. The result is that forward iterators will see all elements
+  // in the array.
+  void Clear()
+  {
+    mArray.Clear();
+    ClearIterators();
+  }
+
+  // Compact the array to minimize the memory it uses
+  void Compact() { mArray.Compact(); }
+
+  // Returns the number of bytes on the heap taken up by this object, not
+  // including sizeof(*this). If you want to measure anything hanging off the
+  // array, you must iterate over the elements and measure them individually;
+  // hence the "Shallow" prefix.
+  size_t ShallowSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return mArray.ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  //
+  // Iterators
+  //
+
+  // Base class for iterators. Do not use this directly.
+  class Iterator : public Iterator_base
+  {
+  protected:
+    friend class nsAutoTObserverArray;
+    typedef nsAutoTObserverArray<T, N> array_type;
+
+    Iterator(index_type aPosition, const array_type& aArray)
+      : Iterator_base(aPosition, aArray.mIterators)
+      , mArray(const_cast<array_type&>(aArray))
+    {
+      aArray.mIterators = this;
+    }
+
+    ~Iterator()
+    {
+      NS_ASSERTION(mArray.mIterators == this,
+                   "Iterators must currently be destroyed in opposite order "
+                   "from the construction order. It is suggested that you "
+                   "simply put them on the stack");
+      mArray.mIterators = mNext;
+    }
+
+    // The array we're iterating
+    array_type& mArray;
+  };
+
+  // Iterates the array forward from beginning to end. mPosition points
+  // to the element that will be returned on next call to GetNext.
+  // Elements:
+  // - prepended to the array during iteration *will not* be traversed
+  // - appended during iteration *will* be traversed
+  // - removed during iteration *will not* be traversed.
+  // @see EndLimitedIterator
+  class ForwardIterator : protected Iterator
+  {
+  public:
+    typedef nsAutoTObserverArray<T, N> array_type;
+    typedef Iterator                   base_type;
+
+    explicit ForwardIterator(const array_type& aArray)
+      : Iterator(0, aArray)
+    {
+    }
+
+    ForwardIterator(const array_type& aArray, index_type aPos)
+      : Iterator(aPos, aArray)
+    {
+    }
+
+    bool operator<(const ForwardIterator& aOther) const
+    {
+      NS_ASSERTION(&this->mArray == &aOther.mArray,
+                   "not iterating the same array");
+      return base_type::mPosition < aOther.mPosition;
+    }
+
+    // Returns true if there are more elements to iterate.
+    // This must precede a call to GetNext(). If false is
+    // returned, GetNext() must not be called.
+    bool HasMore() const
+    {
+      return base_type::mPosition < base_type::mArray.Length();
+    }
+
+    // Returns the next element and steps one step. This must
+    // be preceded by a call to HasMore().
+    // @return The next observer.
+    elem_type& GetNext()
+    {
+      NS_ASSERTION(HasMore(), "iterating beyond end of array");
+      return base_type::mArray.ElementAt(base_type::mPosition++);
+    }
+  };
+
+  // EndLimitedIterator works like ForwardIterator, but will not iterate new
+  // observers appended to the array after the iterator was created.
+  class EndLimitedIterator : protected ForwardIterator
+  {
+  public:
+    typedef nsAutoTObserverArray<T, N> array_type;
+    typedef Iterator                   base_type;
+
+    explicit EndLimitedIterator(const array_type& aArray)
+      : ForwardIterator(aArray)
+      , mEnd(aArray, aArray.Length())
+    {
+    }
+
+    // Returns true if there are more elements to iterate.
+    // This must precede a call to GetNext(). If false is
+    // returned, GetNext() must not be called.
+    bool HasMore() const { return *this < mEnd; }
+
+    // Returns the next element and steps one step. This must
+    // be preceded by a call to HasMore().
+    // @return The next observer.
+    elem_type& GetNext()
+    {
+      NS_ASSERTION(HasMore(), "iterating beyond end of array");
+      return base_type::mArray.ElementAt(base_type::mPosition++);
+    }
+
+  private:
+    ForwardIterator mEnd;
+  };
+
+  // Iterates the array backward from end to start. mPosition points
+  // to the element that was returned last.
+  // Elements:
+  // - prepended to the array during iteration *will* be traversed,
+  //   unless the iteration already arrived at the first element
+  // - appended during iteration *will not* be traversed
+  // - removed during iteration *will not* be traversed.
+  class BackwardIterator : protected Iterator
+  {
+  public:
+    typedef nsAutoTObserverArray<T, N> array_type;
+    typedef Iterator                   base_type;
+
+    explicit BackwardIterator(const array_type& aArray)
+      : Iterator(aArray.Length(), aArray)
+    {
+    }
+
+    // Returns true if there are more elements to iterate.
+    // This must precede a call to GetNext(). If false is
+    // returned, GetNext() must not be called.
+    bool HasMore() const { return base_type::mPosition > 0; }
+
+    // Returns the next element and steps one step. This must
+    // be preceded by a call to HasMore().
+    // @return The next observer.
+    elem_type& GetNext()
+    {
+      NS_ASSERTION(HasMore(), "iterating beyond start of array");
+      return base_type::mArray.ElementAt(--base_type::mPosition);
+    }
+
+    // Removes the element at the current iterator position.
+    // (the last element returned from |GetNext()|)
+    // This will not affect the next call to |GetNext()|
+    void Remove()
+    {
+      return base_type::mArray.RemoveElementAt(base_type::mPosition);
+    }
+  };
+
+protected:
+  AutoTArray<T, N> mArray;
+};
+
+template<class T>
+class nsTObserverArray : public nsAutoTObserverArray<T, 0>
+{
+public:
+  typedef nsAutoTObserverArray<T, 0>       base_type;
+  typedef nsTObserverArray_base::size_type size_type;
+
+  //
+  // Initialization methods
+  //
+
+  nsTObserverArray() {}
+
+  // Initialize this array and pre-allocate some number of elements.
+  explicit nsTObserverArray(size_type aCapacity)
+  {
+    base_type::mArray.SetCapacity(aCapacity);
+  }
+};
+
+template<typename T, size_t N>
+inline void
+ImplCycleCollectionUnlink(nsAutoTObserverArray<T, N>& aField)
+{
+  aField.Clear();
+}
+
+template<typename T, size_t N>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            nsAutoTObserverArray<T, N>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  aFlags |= CycleCollectionEdgeNameArrayFlag;
+  size_t length = aField.Length();
+  for (size_t i = 0; i < length; ++i) {
+    ImplCycleCollectionTraverse(aCallback, aField.ElementAt(i), aName, aFlags);
+  }
+}
+
+// XXXbz I wish I didn't have to pass in the observer type, but I
+// don't see a way to get it out of array_.
+// Note that this macro only works if the array holds pointers to XPCOM objects.
+#define NS_OBSERVER_ARRAY_NOTIFY_XPCOM_OBSERVERS(array_, obstype_, func_, params_) \
+  PR_BEGIN_MACRO                                                             \
+    nsTObserverArray<obstype_ *>::ForwardIterator iter_(array_);             \
+    RefPtr<obstype_> obs_;                                                 \
+    while (iter_.HasMore()) {                                                 \
+      obs_ = iter_.GetNext();                                                \
+      obs_ -> func_ params_ ;                                                \
+    }                                                                        \
+  PR_END_MACRO
+
+// Note that this macro only works if the array holds pointers to XPCOM objects.
+#define NS_OBSERVER_ARRAY_NOTIFY_OBSERVERS(array_, obstype_, func_, params_) \
+  PR_BEGIN_MACRO                                                             \
+    nsTObserverArray<obstype_ *>::ForwardIterator iter_(array_);             \
+    obstype_* obs_;                                                          \
+    while (iter_.HasMore()) {                                                \
+      obs_ = iter_.GetNext();                                                \
+      obs_ -> func_ params_ ;                                                \
+    }                                                                        \
+  PR_END_MACRO
+
+#define NS_OBSERVER_ARRAY_NOTIFY_OBSERVERS_WITH_QI(array_, basetype_, obstype_, func_, params_) \
+  PR_BEGIN_MACRO                                                             \
+    nsTObserverArray<basetype_ *>::ForwardIterator iter_(array_);            \
+    basetype_* obsbase_;                                                     \
+    while (iter_.HasMore()) {                                                \
+      obsbase_ = iter_.GetNext();                                            \
+      nsCOMPtr<obstype_> obs_ = do_QueryInterface(obsbase_);                 \
+      if (obs_) {                                                            \
+        obs_ -> func_ params_ ;                                              \
+      }                                                                      \
+    }                                                                        \
+  PR_END_MACRO
+#endif // nsTObserverArray_h___
diff --git a/xpcom/glue/nsTPriorityQueue.h b/xpcom/glue/nsTPriorityQueue.h
new file mode 100644
index 000000000..20a0fc8a5
--- /dev/null
+++ b/xpcom/glue/nsTPriorityQueue.h
@@ -0,0 +1,161 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef NS_TPRIORITY_QUEUE_H_
+#define NS_TPRIORITY_QUEUE_H_
+
+#include "nsTArray.h"
+#include "nsDebug.h"
+
+/**
+ * A templatized priority queue data structure that uses an nsTArray to serve as
+ * a binary heap. The default comparator causes this to act like a min-heap.
+ * Only the LessThan method of the comparator is used.
+ */
+template<class T, class Compare = nsDefaultComparator<T, T>>
+class nsTPriorityQueue
+{
+public:
+  typedef typename nsTArray<T>::size_type size_type;
+
+  /**
+   * Default constructor also creates a comparator object using the default
+   * constructor for type Compare.
+   */
+  nsTPriorityQueue() : mCompare(Compare()) {}
+
+  /**
+   * Constructor to allow a specific instance of a comparator object to be
+   * used.
+   */
+  explicit nsTPriorityQueue(const Compare& aComp) : mCompare(aComp) {}
+
+  /**
+   * Copy constructor
+   */
+  nsTPriorityQueue(const nsTPriorityQueue& aOther)
+    : mElements(aOther.mElements)
+    , mCompare(aOther.mCompare)
+  {
+  }
+
+  /**
+   * @return True if the queue is empty or false otherwise.
+   */
+  bool IsEmpty() const { return mElements.IsEmpty(); }
+
+  /**
+   * @return The number of elements in the queue.
+   */
+  size_type Length() const { return mElements.Length(); }
+
+  /**
+   * @return The topmost element in the queue without changing the queue. This
+   * is the element 'a' such that there is no other element 'b' in the queue for
+   * which Compare(b, a) returns true. (Since this container does not check
+   * for duplicate entries there may exist 'b' for which Compare(a, b) returns
+   * false.)
+   */
+  const T& Top() const
+  {
+    MOZ_ASSERT(!mElements.IsEmpty(), "Empty queue");
+    return mElements[0];
+  }
+
+  /**
+   * Adds an element to the queue
+   * @param aElement The element to add
+   * @return true on success, false on out of memory.
+   */
+  bool Push(const T& aElement)
+  {
+    T* elem = mElements.AppendElement(aElement);
+    if (!elem) {
+      return false;  // Out of memory
+    }
+
+    // Sift up
+    size_type i = mElements.Length() - 1;
+    while (i) {
+      size_type parent = (size_type)((i - 1) / 2);
+      if (mCompare.LessThan(mElements[parent], mElements[i])) {
+        break;
+      }
+      Swap(i, parent);
+      i = parent;
+    }
+
+    return true;
+  }
+
+  /**
+   * Removes and returns the top-most element from the queue.
+   * @return The topmost element, that is, the element 'a' such that there is no
+   * other element 'b' in the queue for which Compare(b, a) returns true.
+   * @see Top()
+   */
+  T Pop()
+  {
+    MOZ_ASSERT(!mElements.IsEmpty(), "Empty queue");
+    T pop = mElements[0];
+
+    // Move last to front
+    mElements[0] = mElements[mElements.Length() - 1];
+    mElements.TruncateLength(mElements.Length() - 1);
+
+    // Sift down
+    size_type i = 0;
+    while (2 * i + 1 < mElements.Length()) {
+      size_type swap = i;
+      size_type l_child = 2 * i + 1;
+      if (mCompare.LessThan(mElements[l_child], mElements[i])) {
+        swap = l_child;
+      }
+      size_type r_child = l_child + 1;
+      if (r_child < mElements.Length() &&
+          mCompare.LessThan(mElements[r_child], mElements[swap])) {
+        swap = r_child;
+      }
+      if (swap == i) {
+        break;
+      }
+      Swap(i, swap);
+      i = swap;
+    }
+
+    return pop;
+  }
+
+  /**
+   * Removes all elements from the queue.
+   */
+  void Clear() { mElements.Clear(); }
+
+  /**
+   * Provides readonly access to the queue elements as an array. Generally this
+   * should be avoided but may be needed in some situations such as when the
+   * elements contained in the queue need to be enumerated for cycle-collection.
+   * @return A pointer to the first element of the array.  If the array is
+   * empty, then this pointer must not be dereferenced.
+   */
+  const T* Elements() const { return mElements.Elements(); }
+
+protected:
+  /**
+   * Swaps the elements at the specified indices.
+   */
+  void Swap(size_type aIndexA, size_type aIndexB)
+  {
+    T temp = mElements[aIndexA];
+    mElements[aIndexA] = mElements[aIndexB];
+    mElements[aIndexB] = temp;
+  }
+
+  nsTArray<T> mElements;
+  Compare mCompare; // Comparator object
+};
+
+#endif // NS_TPRIORITY_QUEUE_H_
diff --git a/xpcom/glue/nsTWeakRef.h b/xpcom/glue/nsTWeakRef.h
new file mode 100644
index 000000000..6c9a5e8eb
--- /dev/null
+++ b/xpcom/glue/nsTWeakRef.h
@@ -0,0 +1,176 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTWeakRef_h__
+#define nsTWeakRef_h__
+
+#ifndef nsDebug_h___
+#include "nsDebug.h"
+#endif
+
+/**
+ * A weak reference class for use with generic C++ objects.  NOT THREADSAFE!
+ *
+ * Example usage:
+ *
+ *   class A {
+ *   public:
+ *     A() : mWeakSelf(this) {
+ *     }
+ *     ~A() {
+ *       mWeakSelf.forget();
+ *     }
+ *     void Bar() { printf("Bar!\n"); }
+ *     const nsTWeakRef<A> &AsWeakRef() const { return mWeakSelf; }
+ *   private:
+ *     nsTWeakRef<A> mWeakSelf;
+ *   };
+ *
+ *   class B {
+ *   public:
+ *     void SetA(const nsTWeakRef<A> &a) {
+ *       mA = a;
+ *     }
+ *     void Foo() {
+ *       if (mA)
+ *         mA->Bar();
+ *     }
+ *   private:
+ *     nsTWeakRef<A> mA;
+ *   };
+ *
+ *   void Test() {
+ *     B b;
+ *     {
+ *       A a;
+ *       b.SetA(a.AsWeakRef());
+ *       b.Foo();  // prints "Bar!"
+ *     }
+ *     b.Foo();  // prints nothing because |a| has already been destroyed
+ *   }
+ *
+ * One can imagine much more complex examples, especially when asynchronous
+ * event processing is involved.
+ *
+ * Keep in mind that you should only ever need a class like this when you have
+ * multiple instances of B, such that it is not possible for A and B to simply
+ * have pointers to one another.
+ */
+template<class Type>
+class nsTWeakRef
+{
+public:
+  ~nsTWeakRef()
+  {}
+
+  /**
+   * Construct from an object pointer (may be null).
+   */
+  explicit nsTWeakRef(Type* aObj = nullptr)
+  {
+    if (aObj) {
+      mRef = new Inner(aObj);
+    } else {
+      mRef = nullptr;
+    }
+  }
+
+  /**
+   * Construct from another weak reference object.
+   */
+  explicit nsTWeakRef(const nsTWeakRef<Type>& aOther) : mRef(aOther.mRef)
+  {}
+
+  /**
+   * Assign from an object pointer.
+   */
+  nsTWeakRef<Type>& operator=(Type* aObj)
+  {
+    if (aObj) {
+      mRef = new Inner(aObj);
+    } else {
+      mRef = nullptr;
+    }
+    return *this;
+  }
+
+  /**
+   * Assign from another weak reference object.
+   */
+  nsTWeakRef<Type>& operator=(const nsTWeakRef<Type>& aOther)
+  {
+    mRef = aOther.mRef;
+    return *this;
+  }
+
+  /**
+   * Get the referenced object.  This method may return null if the reference
+   * has been cleared or if an out-of-memory error occurred at assignment.
+   */
+  Type* get() const { return mRef ? mRef->mObj : nullptr; }
+
+  /**
+   * Called to "null out" the weak reference.  Typically, the object referenced
+   * by this weak reference calls this method when it is being destroyed.
+   * @returns The former referenced object.
+   */
+  Type* forget()
+  {
+    Type* obj;
+    if (mRef) {
+      obj = mRef->mObj;
+      mRef->mObj = nullptr;
+      mRef = nullptr;
+    } else {
+      obj = nullptr;
+    }
+    return obj;
+  }
+
+  /**
+   * Allow |*this| to be treated as a |Type*| for convenience.
+   */
+  operator Type*() const { return get(); }
+
+  /**
+   * Allow |*this| to be treated as a |Type*| for convenience.  Use with
+   * caution since this method will crash if the referenced object is null.
+   */
+  Type* operator->() const MOZ_NO_ADDREF_RELEASE_ON_RETURN
+  {
+    NS_ASSERTION(mRef && mRef->mObj,
+                 "You can't dereference a null weak reference with operator->().");
+    return get();
+  }
+
+private:
+
+  struct Inner
+  {
+    int     mCnt;
+    Type*   mObj;
+
+    explicit Inner(Type* aObj)
+      : mCnt(1)
+      , mObj(aObj)
+    {
+    }
+    void AddRef()
+    {
+      ++mCnt;
+    }
+    void Release()
+    {
+      if (--mCnt == 0) {
+        delete this;
+      }
+    }
+  };
+
+  RefPtr<Inner> mRef;
+};
+
+#endif  // nsTWeakRef_h__
diff --git a/xpcom/glue/nsTextFormatter.cpp b/xpcom/glue/nsTextFormatter.cpp
new file mode 100644
index 000000000..ab9941d15
--- /dev/null
+++ b/xpcom/glue/nsTextFormatter.cpp
@@ -0,0 +1,1394 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Portable safe sprintf code.
+ *
+ * Code based on mozilla/nsprpub/src/io/prprf.c rev 3.7
+ *
+ * Contributor(s):
+ *   Kipp E.B. Hickman  <kipp@netscape.com>  (original author)
+ *   Frank Yung-Fong Tang  <ftang@netscape.com>
+ *   Daniele Nicolodi  <daniele@grinta.net>
+ */
+
+/*
+ * Copied from xpcom/ds/nsTextFormatter.cpp r1.22
+ *     Changed to use nsMemory and Frozen linkage
+ *                  -- Prasad <prasad@medhas.org>
+ */
+
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+#include "prdtoa.h"
+#include "mozilla/Logging.h"
+#include "mozilla/Sprintf.h"
+#include "prmem.h"
+#include "nsCRTGlue.h"
+#include "nsTextFormatter.h"
+#include "nsMemory.h"
+
+/*
+** Note: on some platforms va_list is defined as an array,
+** and requires array notation.
+*/
+
+#ifdef HAVE_VA_COPY
+#define VARARGS_ASSIGN(foo, bar)        VA_COPY(foo,bar)
+#elif defined(HAVE_VA_LIST_AS_ARRAY)
+#define VARARGS_ASSIGN(foo, bar)	foo[0] = bar[0]
+#else
+#define VARARGS_ASSIGN(foo, bar)	(foo) = (bar)
+#endif
+
+typedef struct SprintfStateStr SprintfState;
+
+struct SprintfStateStr
+{
+  int (*stuff)(SprintfState* aState, const char16_t* aStr, uint32_t aLen);
+
+  char16_t* base;
+  char16_t* cur;
+  uint32_t maxlen;
+
+  void* stuffclosure;
+};
+
+/*
+** Numbered Arguement State
+*/
+struct NumArgState
+{
+  int type;    /* type of the current ap */
+  va_list ap;  /* point to the corresponding position on ap */
+
+  enum Type
+  {
+    INT16,
+    UINT16,
+    INTN,
+    UINTN,
+    INT32,
+    UINT32,
+    INT64,
+    UINT64,
+    STRING,
+    DOUBLE,
+    INTSTR,
+    UNISTRING,
+    UNKNOWN
+  };
+};
+
+#define NAS_DEFAULT_NUM 20  /* default number of NumberedArgumentState array */
+
+#define _LEFT		0x1
+#define _SIGNED		0x2
+#define _SPACED		0x4
+#define _ZEROS		0x8
+#define _NEG		0x10
+
+#define ELEMENTS_OF(array_) (sizeof(array_) / sizeof(array_[0]))
+
+#define PR_CHECK_DELETE(nas) if (nas && (nas != nasArray)) { PR_DELETE(nas); }
+
+/*
+** Fill into the buffer using the data in src
+*/
+static int
+fill2(SprintfState* aState, const char16_t* aSrc, int aSrcLen, int aWidth,
+      int aFlags)
+{
+  char16_t space = ' ';
+  int rv;
+
+  aWidth -= aSrcLen;
+  /* Right adjusting */
+  if ((aWidth > 0) && ((aFlags & _LEFT) == 0)) {
+    if (aFlags & _ZEROS) {
+      space = '0';
+    }
+    while (--aWidth >= 0) {
+      rv = (*aState->stuff)(aState, &space, 1);
+      if (rv < 0) {
+        return rv;
+      }
+    }
+  }
+
+  /* Copy out the source data */
+  rv = (*aState->stuff)(aState, aSrc, aSrcLen);
+  if (rv < 0) {
+    return rv;
+  }
+
+  /* Left adjusting */
+  if ((aWidth > 0) && ((aFlags & _LEFT) != 0)) {
+    while (--aWidth >= 0) {
+      rv = (*aState->stuff)(aState, &space, 1);
+      if (rv < 0) {
+        return rv;
+      }
+    }
+  }
+  return 0;
+}
+
+/*
+** Fill a number. The order is: optional-sign zero-filling conversion-digits
+*/
+static int
+fill_n(SprintfState* aState, const char16_t* aSrc, int aSrcLen, int aWidth,
+       int aPrec, int aType, int aFlags)
+{
+  int zerowidth   = 0;
+  int precwidth   = 0;
+  int signwidth   = 0;
+  int leftspaces  = 0;
+  int rightspaces = 0;
+  int cvtwidth;
+  int rv;
+  char16_t sign;
+  char16_t space = ' ';
+  char16_t zero = '0';
+
+  if ((aType & 1) == 0) {
+    if (aFlags & _NEG) {
+      sign = '-';
+      signwidth = 1;
+    } else if (aFlags & _SIGNED) {
+      sign = '+';
+      signwidth = 1;
+    } else if (aFlags & _SPACED) {
+      sign = ' ';
+      signwidth = 1;
+    }
+  }
+  cvtwidth = signwidth + aSrcLen;
+
+  if (aPrec > 0) {
+    if (aPrec > aSrcLen) {
+      /* Need zero filling */
+      precwidth = aPrec - aSrcLen;
+      cvtwidth += precwidth;
+    }
+  }
+
+  if ((aFlags & _ZEROS) && (aPrec < 0)) {
+    if (aWidth > cvtwidth) {
+      /* Zero filling */
+      zerowidth = aWidth - cvtwidth;
+      cvtwidth += zerowidth;
+    }
+  }
+
+  if (aFlags & _LEFT) {
+    if (aWidth > cvtwidth) {
+      /* Space filling on the right (i.e. left adjusting) */
+      rightspaces = aWidth - cvtwidth;
+    }
+  } else {
+    if (aWidth > cvtwidth) {
+      /* Space filling on the left (i.e. right adjusting) */
+      leftspaces = aWidth - cvtwidth;
+    }
+  }
+  while (--leftspaces >= 0) {
+    rv = (*aState->stuff)(aState, &space, 1);
+    if (rv < 0) {
+      return rv;
+    }
+  }
+  if (signwidth) {
+    rv = (*aState->stuff)(aState, &sign, 1);
+    if (rv < 0) {
+      return rv;
+    }
+  }
+  while (--precwidth >= 0) {
+    rv = (*aState->stuff)(aState,  &space, 1);
+    if (rv < 0) {
+      return rv;
+    }
+  }
+  while (--zerowidth >= 0) {
+    rv = (*aState->stuff)(aState,  &zero, 1);
+    if (rv < 0) {
+      return rv;
+    }
+  }
+  rv = (*aState->stuff)(aState, aSrc, aSrcLen);
+  if (rv < 0) {
+    return rv;
+  }
+  while (--rightspaces >= 0) {
+    rv = (*aState->stuff)(aState,  &space, 1);
+    if (rv < 0) {
+      return rv;
+    }
+  }
+  return 0;
+}
+
+/*
+** Convert a long into its printable form
+*/
+static int
+cvt_l(SprintfState* aState, long aNum, int aWidth, int aPrec, int aRadix,
+      int aType, int aFlags, const char16_t* aHexStr)
+{
+  char16_t cvtbuf[100];
+  char16_t* cvt;
+  int digits;
+
+  /* according to the man page this needs to happen */
+  if ((aPrec == 0) && (aNum == 0)) {
+    return 0;
+  }
+
+  /*
+  ** Converting decimal is a little tricky. In the unsigned case we
+  ** need to stop when we hit 10 digits. In the signed case, we can
+  ** stop when the number is zero.
+  */
+  cvt = &cvtbuf[0] + ELEMENTS_OF(cvtbuf);
+  digits = 0;
+  while (aNum) {
+    int digit = (((unsigned long)aNum) % aRadix) & 0xF;
+    *--cvt = aHexStr[digit];
+    digits++;
+    aNum = (long)(((unsigned long)aNum) / aRadix);
+  }
+  if (digits == 0) {
+    *--cvt = '0';
+    digits++;
+  }
+
+  /*
+  ** Now that we have the number converted without its sign, deal with
+  ** the sign and zero padding.
+  */
+  return fill_n(aState, cvt, digits, aWidth, aPrec, aType, aFlags);
+}
+
+/*
+** Convert a 64-bit integer into its printable form
+*/
+static int
+cvt_ll(SprintfState* aState, int64_t aNum, int aWidth, int aPrec, int aRadix,
+       int aType, int aFlags, const char16_t* aHexStr)
+{
+  char16_t cvtbuf[100];
+  char16_t* cvt;
+  int digits;
+  int64_t rad;
+
+  /* according to the man page this needs to happen */
+  if (aPrec == 0 && aNum == 0) {
+    return 0;
+  }
+
+  /*
+  ** Converting decimal is a little tricky. In the unsigned case we
+  ** need to stop when we hit 10 digits. In the signed case, we can
+  ** stop when the number is zero.
+  */
+  rad = aRadix;
+  cvt = &cvtbuf[0] + ELEMENTS_OF(cvtbuf);
+  digits = 0;
+  while (aNum != 0) {
+    *--cvt = aHexStr[int32_t(aNum % rad) & 0xf];
+    digits++;
+    aNum /= rad;
+  }
+  if (digits == 0) {
+    *--cvt = '0';
+    digits++;
+  }
+
+  /*
+  ** Now that we have the number converted without its sign, deal with
+  ** the sign and zero padding.
+  */
+  return fill_n(aState, cvt, digits, aWidth, aPrec, aType, aFlags);
+}
+
+/*
+** Convert a double precision floating point number into its printable
+** form.
+*/
+static int
+cvt_f(SprintfState* aState, double aDouble, int aWidth, int aPrec,
+      const char16_t aType, int aFlags)
+{
+  int    mode = 2;
+  int    decpt;
+  int    sign;
+  char   buf[256];
+  char*  bufp = buf;
+  int    bufsz = 256;
+  char   num[256];
+  char*  nump;
+  char*  endnum;
+  int    numdigits = 0;
+  char   exp = 'e';
+
+  if (aPrec == -1) {
+    aPrec = 6;
+  } else if (aPrec > 50) {
+    // limit precision to avoid PR_dtoa bug 108335
+    // and to prevent buffers overflows
+    aPrec = 50;
+  }
+
+  switch (aType) {
+    case 'f':
+      numdigits = aPrec;
+      mode = 3;
+      break;
+    case 'E':
+      exp = 'E';
+      MOZ_FALLTHROUGH;
+    case 'e':
+      numdigits = aPrec + 1;
+      mode = 2;
+      break;
+    case 'G':
+      exp = 'E';
+      MOZ_FALLTHROUGH;
+    case 'g':
+      if (aPrec == 0) {
+        aPrec = 1;
+      }
+      numdigits = aPrec;
+      mode = 2;
+      break;
+    default:
+      NS_ERROR("invalid aType passed to cvt_f");
+  }
+
+  if (PR_dtoa(aDouble, mode, numdigits, &decpt, &sign,
+              &endnum, num, bufsz) == PR_FAILURE) {
+    buf[0] = '\0';
+    return -1;
+  }
+  numdigits = endnum - num;
+  nump = num;
+
+  if (sign) {
+    *bufp++ = '-';
+  } else if (aFlags & _SIGNED) {
+    *bufp++ = '+';
+  }
+
+  if (decpt == 9999) {
+    while ((*bufp++ = *nump++)) {
+    }
+  } else {
+
+    switch (aType) {
+
+      case 'E':
+      case 'e':
+
+        *bufp++ = *nump++;
+        if (aPrec > 0) {
+          *bufp++ = '.';
+          while (*nump) {
+            *bufp++ = *nump++;
+            aPrec--;
+          }
+          while (aPrec-- > 0) {
+            *bufp++ = '0';
+          }
+        }
+        *bufp++ = exp;
+
+        snprintf(bufp, bufsz - (bufp - buf), "%+03d", decpt - 1);
+        break;
+
+      case 'f':
+
+        if (decpt < 1) {
+          *bufp++ = '0';
+          if (aPrec > 0) {
+            *bufp++ = '.';
+            while (decpt++ && aPrec-- > 0) {
+              *bufp++ = '0';
+            }
+            while (*nump && aPrec-- > 0) {
+              *bufp++ = *nump++;
+            }
+            while (aPrec-- > 0) {
+              *bufp++ = '0';
+            }
+          }
+        } else {
+          while (*nump && decpt-- > 0) {
+            *bufp++ = *nump++;
+          }
+          while (decpt-- > 0) {
+            *bufp++ = '0';
+          }
+          if (aPrec > 0) {
+            *bufp++ = '.';
+            while (*nump && aPrec-- > 0) {
+              *bufp++ = *nump++;
+            }
+            while (aPrec-- > 0) {
+              *bufp++ = '0';
+            }
+          }
+        }
+        *bufp = '\0';
+        break;
+
+      case 'G':
+      case 'g':
+
+        if ((decpt < -3) || ((decpt - 1) >= aPrec)) {
+          *bufp++ = *nump++;
+          numdigits--;
+          if (numdigits > 0) {
+            *bufp++ = '.';
+            while (*nump) {
+              *bufp++ = *nump++;
+            }
+          }
+          *bufp++ = exp;
+          snprintf(bufp, bufsz - (bufp - buf), "%+03d", decpt - 1);
+        } else {
+          if (decpt < 1) {
+            *bufp++ = '0';
+            if (aPrec > 0) {
+              *bufp++ = '.';
+              while (decpt++) {
+                *bufp++ = '0';
+              }
+              while (*nump) {
+                *bufp++ = *nump++;
+              }
+            }
+          } else {
+            while (*nump && decpt-- > 0) {
+              *bufp++ = *nump++;
+              numdigits--;
+            }
+            while (decpt-- > 0) {
+              *bufp++ = '0';
+            }
+            if (numdigits > 0) {
+              *bufp++ = '.';
+              while (*nump) {
+                *bufp++ = *nump++;
+              }
+            }
+          }
+          *bufp = '\0';
+        }
+    }
+  }
+
+  char16_t rbuf[256];
+  char16_t* rbufp = rbuf;
+  bufp = buf;
+  // cast to char16_t
+  while ((*rbufp++ = *bufp++)) {
+  }
+  *rbufp = '\0';
+
+  return fill2(aState, rbuf, NS_strlen(rbuf), aWidth, aFlags);
+}
+
+/*
+** Convert a string into its printable form. |aWidth| is the output
+** width. |aPrec| is the maximum number of characters of |aStr| to output,
+** where -1 means until NUL.
+*/
+static int
+cvt_S(SprintfState* aState, const char16_t* aStr, int aWidth, int aPrec,
+      int aFlags)
+{
+  int slen;
+
+  if (aPrec == 0) {
+    return 0;
+  }
+
+  /* Limit string length by precision value */
+  slen = aStr ? NS_strlen(aStr) : 6;
+  if (aPrec > 0) {
+    if (aPrec < slen) {
+      slen = aPrec;
+    }
+  }
+
+  /* and away we go */
+  return fill2(aState, aStr ? aStr : u"(null)", slen, aWidth, aFlags);
+}
+
+/*
+** Convert a string into its printable form.  |aWidth| is the output
+** width. |aPrec| is the maximum number of characters of |aStr| to output,
+** where -1 means until NUL.
+*/
+static int
+cvt_s(SprintfState* aState, const char* aStr, int aWidth, int aPrec, int aFlags)
+{
+  NS_ConvertUTF8toUTF16 utf16Val(aStr);
+  return cvt_S(aState, utf16Val.get(), aWidth, aPrec, aFlags);
+}
+
+/*
+** BuildArgArray stands for Numbered Argument list Sprintf
+** for example,
+**	fmp = "%4$i, %2$d, %3s, %1d";
+** the number must start from 1, and no gap among them
+*/
+
+static struct NumArgState*
+BuildArgArray(const char16_t* aFmt, va_list aAp, int* aRv,
+              struct NumArgState* aNasArray)
+{
+  int number = 0, cn = 0, i;
+  const char16_t* p;
+  char16_t  c;
+  struct NumArgState* nas;
+
+  /*
+  **	first pass:
+  **	detemine how many legal % I have got, then allocate space
+  */
+  p = aFmt;
+  *aRv = 0;
+  i = 0;
+  while ((c = *p++) != 0) {
+    if (c != '%') {
+      continue;
+    }
+    /* skip %% case */
+    if ((c = *p++) == '%') {
+      continue;
+    }
+
+    while (c != 0) {
+      if (c > '9' || c < '0') {
+        /* numbered argument csae */
+        if (c == '$') {
+          if (i > 0) {
+            *aRv = -1;
+            return nullptr;
+          }
+          number++;
+          break;
+
+        } else {
+          /* non-numbered argument case */
+          if (number > 0) {
+            *aRv = -1;
+            return nullptr;
+          }
+          i = 1;
+          break;
+        }
+      }
+      c = *p++;
+    }
+  }
+
+  if (number == 0) {
+    return nullptr;
+  }
+
+  if (number > NAS_DEFAULT_NUM) {
+    nas = (struct NumArgState*)moz_xmalloc(number * sizeof(struct NumArgState));
+    if (!nas) {
+      *aRv = -1;
+      return nullptr;
+    }
+  } else {
+    nas = aNasArray;
+  }
+
+  for (i = 0; i < number; i++) {
+    nas[i].type = NumArgState::UNKNOWN;
+  }
+
+  /*
+  ** second pass:
+  ** set nas[].type
+  */
+  p = aFmt;
+  while ((c = *p++) != 0) {
+    if (c != '%') {
+      continue;
+    }
+    c = *p++;
+    if (c == '%') {
+      continue;
+    }
+    cn = 0;
+    /* should improve error check later */
+    while (c && c != '$') {
+      cn = cn * 10 + c - '0';
+      c = *p++;
+    }
+
+    if (!c || cn < 1 || cn > number) {
+      *aRv = -1;
+      break;
+    }
+
+    /* nas[cn] starts from 0, and make sure
+             nas[cn].type is not assigned */
+    cn--;
+    if (nas[cn].type != NumArgState::UNKNOWN) {
+      continue;
+    }
+
+    c = *p++;
+
+    /* width */
+    if (c == '*') {
+      /* not supported feature, for the argument is not numbered */
+      *aRv = -1;
+      break;
+    } else {
+      while ((c >= '0') && (c <= '9')) {
+        c = *p++;
+      }
+    }
+
+    /* precision */
+    if (c == '.') {
+      c = *p++;
+      if (c == '*') {
+        /* not supported feature, for the argument is not numbered */
+        *aRv = -1;
+        break;
+      } else {
+        while ((c >= '0') && (c <= '9')) {
+          c = *p++;
+        }
+      }
+    }
+
+    /* size */
+    nas[cn].type = NumArgState::INTN;
+    if (c == 'h') {
+      nas[cn].type = NumArgState::INT16;
+      c = *p++;
+    } else if (c == 'L') {
+      /* XXX not quite sure here */
+      nas[cn].type = NumArgState::INT64;
+      c = *p++;
+    } else if (c == 'l') {
+      nas[cn].type = NumArgState::INT32;
+      c = *p++;
+      if (c == 'l') {
+        nas[cn].type = NumArgState::INT64;
+        c = *p++;
+      }
+    }
+
+    /* format */
+    switch (c) {
+      case 'd':
+      case 'c':
+      case 'i':
+      case 'o':
+      case 'u':
+      case 'x':
+      case 'X':
+        break;
+
+      case 'e':
+      case 'f':
+      case 'g':
+        nas[cn].type = NumArgState::DOUBLE;
+        break;
+
+      case 'p':
+        /* XXX should use cpp */
+        if (sizeof(void*) == sizeof(int32_t)) {
+          nas[cn].type = NumArgState::UINT32;
+        } else if (sizeof(void*) == sizeof(int64_t)) {
+          nas[cn].type = NumArgState::UINT64;
+        } else if (sizeof(void*) == sizeof(int)) {
+          nas[cn].type = NumArgState::UINTN;
+        } else {
+          nas[cn].type = NumArgState::UNKNOWN;
+        }
+        break;
+
+      case 'C':
+        /* XXX not supported I suppose */
+        PR_ASSERT(0);
+        nas[cn].type = NumArgState::UNKNOWN;
+        break;
+
+      case 'S':
+        nas[cn].type = NumArgState::UNISTRING;
+        break;
+
+      case 's':
+        nas[cn].type = NumArgState::STRING;
+        break;
+
+      case 'n':
+        nas[cn].type = NumArgState::INTSTR;
+        break;
+
+      default:
+        PR_ASSERT(0);
+        nas[cn].type = NumArgState::UNKNOWN;
+        break;
+    }
+
+    /* get a legal para. */
+    if (nas[cn].type == NumArgState::UNKNOWN) {
+      *aRv = -1;
+      break;
+    }
+  }
+
+
+  /*
+  ** third pass
+  ** fill the nas[cn].ap
+  */
+  if (*aRv < 0) {
+    if (nas != aNasArray) {
+      PR_DELETE(nas);
+    }
+    return nullptr;
+  }
+
+  cn = 0;
+  while (cn < number) {
+    if (nas[cn].type == NumArgState::UNKNOWN) {
+      cn++;
+      continue;
+    }
+
+    VARARGS_ASSIGN(nas[cn].ap, aAp);
+
+    switch (nas[cn].type) {
+      case NumArgState::INT16:
+      case NumArgState::UINT16:
+      case NumArgState::INTN:
+      case NumArgState::UINTN:     (void)va_arg(aAp, int);         break;
+
+      case NumArgState::INT32:     (void)va_arg(aAp, int32_t);     break;
+
+      case NumArgState::UINT32:    (void)va_arg(aAp, uint32_t);    break;
+
+      case NumArgState::INT64:     (void)va_arg(aAp, int64_t);     break;
+
+      case NumArgState::UINT64:    (void)va_arg(aAp, uint64_t);    break;
+
+      case NumArgState::STRING:    (void)va_arg(aAp, char*);       break;
+
+      case NumArgState::INTSTR:    (void)va_arg(aAp, int*);        break;
+
+      case NumArgState::DOUBLE:    (void)va_arg(aAp, double);      break;
+
+      case NumArgState::UNISTRING: (void)va_arg(aAp, char16_t*);   break;
+
+      default:
+        if (nas != aNasArray) {
+          PR_DELETE(nas);
+        }
+        *aRv = -1;
+        va_end(aAp);
+        return nullptr;
+    }
+    cn++;
+  }
+  va_end(aAp);
+  return nas;
+}
+
+
+/*
+** The workhorse sprintf code.
+*/
+static int
+dosprintf(SprintfState* aState, const char16_t* aFmt, va_list aAp)
+{
+  char16_t c;
+  int flags, width, prec, radix, type;
+  union
+  {
+    char16_t ch;
+    int i;
+    long l;
+    int64_t ll;
+    double d;
+    const char* s;
+    const char16_t* S;
+    int* ip;
+  } u;
+  char16_t space = ' ';
+
+  nsAutoString hex;
+  hex.AssignLiteral("0123456789abcdef");
+
+  nsAutoString HEX;
+  HEX.AssignLiteral("0123456789ABCDEF");
+
+  const char16_t* hexp;
+  int rv, i;
+  struct NumArgState* nas = nullptr;
+  struct NumArgState  nasArray[NAS_DEFAULT_NUM];
+
+
+  /*
+  ** build an argument array, IF the aFmt is numbered argument
+  ** list style, to contain the Numbered Argument list pointers
+  */
+  nas = BuildArgArray(aFmt, aAp, &rv, nasArray);
+  if (rv < 0) {
+    /* the aFmt contains error Numbered Argument format, jliu@netscape.com */
+    PR_ASSERT(0);
+    return rv;
+  }
+
+  while ((c = *aFmt++) != 0) {
+    if (c != '%') {
+      rv = (*aState->stuff)(aState, aFmt - 1, 1);
+      if (rv < 0) {
+        va_end(aAp);
+        PR_CHECK_DELETE(nas);
+        return rv;
+      }
+      continue;
+    }
+
+    /*
+    ** Gobble up the % format string. Hopefully we have handled all
+    ** of the strange cases!
+    */
+    flags = 0;
+    c = *aFmt++;
+    if (c == '%') {
+      /* quoting a % with %% */
+      rv = (*aState->stuff)(aState, aFmt - 1, 1);
+      if (rv < 0) {
+        va_end(aAp);
+        PR_CHECK_DELETE(nas);
+        return rv;
+      }
+      continue;
+    }
+
+    if (nas) {
+      /* the aFmt contains the Numbered Arguments feature */
+      i = 0;
+      /* should improve error check later */
+      while (c && c != '$') {
+        i = (i * 10) + (c - '0');
+        c = *aFmt++;
+      }
+
+      if (nas[i - 1].type == NumArgState::UNKNOWN) {
+        if (nas != nasArray) {
+          PR_DELETE(nas);
+        }
+        va_end(aAp);
+        return -1;
+      }
+
+      VARARGS_ASSIGN(aAp, nas[i - 1].ap);
+      c = *aFmt++;
+    }
+
+    /*
+     * Examine optional flags.  Note that we do not implement the
+     * '#' flag of sprintf().  The ANSI C spec. of the '#' flag is
+     * somewhat ambiguous and not ideal, which is perhaps why
+     * the various sprintf() implementations are inconsistent
+     * on this feature.
+     */
+    while ((c == '-') || (c == '+') || (c == ' ') || (c == '0')) {
+      if (c == '-') {
+        flags |= _LEFT;
+      }
+      if (c == '+') {
+        flags |= _SIGNED;
+      }
+      if (c == ' ') {
+        flags |= _SPACED;
+      }
+      if (c == '0') {
+        flags |= _ZEROS;
+      }
+      c = *aFmt++;
+    }
+    if (flags & _SIGNED) {
+      flags &= ~_SPACED;
+    }
+    if (flags & _LEFT) {
+      flags &= ~_ZEROS;
+    }
+
+    /* width */
+    if (c == '*') {
+      c = *aFmt++;
+      width = va_arg(aAp, int);
+    } else {
+      width = 0;
+      while ((c >= '0') && (c <= '9')) {
+        width = (width * 10) + (c - '0');
+        c = *aFmt++;
+      }
+    }
+
+    /* precision */
+    prec = -1;
+    if (c == '.') {
+      c = *aFmt++;
+      if (c == '*') {
+        c = *aFmt++;
+        prec = va_arg(aAp, int);
+      } else {
+        prec = 0;
+        while ((c >= '0') && (c <= '9')) {
+          prec = (prec * 10) + (c - '0');
+          c = *aFmt++;
+        }
+      }
+    }
+
+    /* size */
+    type = NumArgState::INTN;
+    if (c == 'h') {
+      type = NumArgState::INT16;
+      c = *aFmt++;
+    } else if (c == 'L') {
+      /* XXX not quite sure here */
+      type = NumArgState::INT64;
+      c = *aFmt++;
+    } else if (c == 'l') {
+      type = NumArgState::INT32;
+      c = *aFmt++;
+      if (c == 'l') {
+        type = NumArgState::INT64;
+        c = *aFmt++;
+      }
+    }
+
+    /* format */
+    hexp = hex.get();
+    switch (c) {
+      case 'd':
+      case 'i':                               /* decimal/integer */
+        radix = 10;
+        goto fetch_and_convert;
+
+      case 'o':                               /* octal */
+        radix = 8;
+        type |= 1;
+        goto fetch_and_convert;
+
+      case 'u':                               /* unsigned decimal */
+        radix = 10;
+        type |= 1;
+        goto fetch_and_convert;
+
+      case 'x':                               /* unsigned hex */
+        radix = 16;
+        type |= 1;
+        goto fetch_and_convert;
+
+      case 'X':                               /* unsigned HEX */
+        radix = 16;
+        hexp = HEX.get();
+        type |= 1;
+        goto fetch_and_convert;
+
+        fetch_and_convert:
+        switch (type) {
+          case NumArgState::INT16:
+            u.l = va_arg(aAp, int);
+            if (u.l < 0) {
+              u.l = -u.l;
+              flags |= _NEG;
+            }
+            goto do_long;
+          case NumArgState::UINT16:
+            u.l = va_arg(aAp, int) & 0xffff;
+            goto do_long;
+          case NumArgState::INTN:
+            u.l = va_arg(aAp, int);
+            if (u.l < 0) {
+              u.l = -u.l;
+              flags |= _NEG;
+            }
+            goto do_long;
+          case NumArgState::UINTN:
+            u.l = (long)va_arg(aAp, unsigned int);
+            goto do_long;
+
+          case NumArgState::INT32:
+            u.l = va_arg(aAp, int32_t);
+            if (u.l < 0) {
+              u.l = -u.l;
+              flags |= _NEG;
+            }
+            goto do_long;
+          case NumArgState::UINT32:
+            u.l = (long)va_arg(aAp, uint32_t);
+          do_long:
+            rv = cvt_l(aState, u.l, width, prec, radix, type, flags, hexp);
+            if (rv < 0) {
+              va_end(aAp);
+              PR_CHECK_DELETE(nas);
+              return rv;
+            }
+            break;
+
+          case NumArgState::INT64:
+            u.ll = va_arg(aAp, int64_t);
+            if (u.ll < 0) {
+              u.ll = -u.ll;
+              flags |= _NEG;
+            }
+            goto do_longlong;
+          case NumArgState::UINT64:
+            u.ll = va_arg(aAp, uint64_t);
+          do_longlong:
+            rv = cvt_ll(aState, u.ll, width, prec, radix, type, flags, hexp);
+            if (rv < 0) {
+              va_end(aAp);
+              PR_CHECK_DELETE(nas);
+              return rv;
+            }
+            break;
+        }
+        break;
+
+      case 'e':
+      case 'E':
+      case 'f':
+      case 'g':
+      case 'G':
+        u.d = va_arg(aAp, double);
+        rv = cvt_f(aState, u.d, width, prec, c, flags);
+        if (rv < 0) {
+          return rv;
+        }
+        break;
+
+      case 'c':
+        u.ch = va_arg(aAp, int);
+        if ((flags & _LEFT) == 0) {
+          while (width-- > 1) {
+            rv = (*aState->stuff)(aState, &space, 1);
+            if (rv < 0) {
+              va_end(aAp);
+              PR_CHECK_DELETE(nas);
+              return rv;
+            }
+          }
+        }
+        rv = (*aState->stuff)(aState, &u.ch, 1);
+        if (rv < 0) {
+          va_end(aAp);
+          PR_CHECK_DELETE(nas);
+          return rv;
+        }
+        if (flags & _LEFT) {
+          while (width-- > 1) {
+            rv = (*aState->stuff)(aState, &space, 1);
+            if (rv < 0) {
+              va_end(aAp);
+              PR_CHECK_DELETE(nas);
+              return rv;
+            }
+          }
+        }
+        break;
+
+      case 'p':
+        if (sizeof(void*) == sizeof(int32_t)) {
+          type = NumArgState::UINT32;
+        } else if (sizeof(void*) == sizeof(int64_t)) {
+          type = NumArgState::UINT64;
+        } else if (sizeof(void*) == sizeof(int)) {
+          type = NumArgState::UINTN;
+        } else {
+          PR_ASSERT(0);
+          break;
+        }
+        radix = 16;
+        goto fetch_and_convert;
+
+#if 0
+      case 'C':
+        /* XXX not supported I suppose */
+        PR_ASSERT(0);
+        break;
+#endif
+
+      case 'S':
+        u.S = va_arg(aAp, const char16_t*);
+        rv = cvt_S(aState, u.S, width, prec, flags);
+        if (rv < 0) {
+          va_end(aAp);
+          PR_CHECK_DELETE(nas);
+          return rv;
+        }
+        break;
+
+      case 's':
+        u.s = va_arg(aAp, const char*);
+        rv = cvt_s(aState, u.s, width, prec, flags);
+        if (rv < 0) {
+          va_end(aAp);
+          PR_CHECK_DELETE(nas);
+          return rv;
+        }
+        break;
+
+      case 'n':
+        u.ip = va_arg(aAp, int*);
+        if (u.ip) {
+          *u.ip = aState->cur - aState->base;
+        }
+        break;
+
+      default:
+        /* Not a % token after all... skip it */
+#if 0
+        PR_ASSERT(0);
+#endif
+        char16_t perct = '%';
+        rv = (*aState->stuff)(aState, &perct, 1);
+        if (rv < 0) {
+          va_end(aAp);
+          PR_CHECK_DELETE(nas);
+          return rv;
+        }
+        rv = (*aState->stuff)(aState, aFmt - 1, 1);
+        if (rv < 0) {
+          va_end(aAp);
+          PR_CHECK_DELETE(nas);
+          return rv;
+        }
+    }
+  }
+
+  /* Stuff trailing NUL */
+  char16_t null = '\0';
+
+  rv = (*aState->stuff)(aState, &null, 1);
+
+  va_end(aAp);
+  PR_CHECK_DELETE(nas);
+
+  return rv;
+}
+
+/************************************************************************/
+
+static int
+StringStuff(SprintfState* aState, const char16_t* aStr, uint32_t aLen)
+{
+  if (*aStr == '\0') {
+    return 0;
+  }
+
+  ptrdiff_t off = aState->cur - aState->base;
+
+  nsAString* str = static_cast<nsAString*>(aState->stuffclosure);
+  str->Append(aStr, aLen);
+
+  aState->base = str->BeginWriting();
+  aState->cur = aState->base + off;
+
+  return 0;
+}
+
+/*
+** Stuff routine that automatically grows the malloc'd output buffer
+** before it overflows.
+*/
+static int
+GrowStuff(SprintfState* aState, const char16_t* aStr, uint32_t aLen)
+{
+  ptrdiff_t off;
+  char16_t* newbase;
+  uint32_t newlen;
+
+  off = aState->cur - aState->base;
+  if (off + aLen >= aState->maxlen) {
+    /* Grow the buffer */
+    newlen = aState->maxlen + ((aLen > 32) ? aLen : 32);
+    if (aState->base) {
+      newbase = (char16_t*)moz_xrealloc(aState->base,
+                                        newlen * sizeof(char16_t));
+    } else {
+      newbase = (char16_t*)moz_xmalloc(newlen * sizeof(char16_t));
+    }
+    if (!newbase) {
+      /* Ran out of memory */
+      return -1;
+    }
+    aState->base = newbase;
+    aState->maxlen = newlen;
+    aState->cur = aState->base + off;
+  }
+
+  /* Copy data */
+  while (aLen) {
+    --aLen;
+    *aState->cur++ = *aStr++;
+  }
+  MOZ_ASSERT((uint32_t)(aState->cur - aState->base) <= aState->maxlen);
+  return 0;
+}
+
+/*
+** sprintf into a malloc'd buffer
+*/
+char16_t*
+nsTextFormatter::smprintf(const char16_t* aFmt, ...)
+{
+  va_list ap;
+  char16_t* rv;
+
+  va_start(ap, aFmt);
+  rv = nsTextFormatter::vsmprintf(aFmt, ap);
+  va_end(ap);
+  return rv;
+}
+
+uint32_t
+nsTextFormatter::ssprintf(nsAString& aOut, const char16_t* aFmt, ...)
+{
+  va_list ap;
+  uint32_t rv;
+
+  va_start(ap, aFmt);
+  rv = nsTextFormatter::vssprintf(aOut, aFmt, ap);
+  va_end(ap);
+  return rv;
+}
+
+uint32_t
+nsTextFormatter::vssprintf(nsAString& aOut, const char16_t* aFmt, va_list aAp)
+{
+  SprintfState ss;
+  ss.stuff = StringStuff;
+  ss.base = 0;
+  ss.cur = 0;
+  ss.maxlen = 0;
+  ss.stuffclosure = &aOut;
+
+  aOut.Truncate();
+  int n = dosprintf(&ss, aFmt, aAp);
+  return n ? n - 1 : n;
+}
+
+char16_t*
+nsTextFormatter::vsmprintf(const char16_t* aFmt, va_list aAp)
+{
+  SprintfState ss;
+  int rv;
+
+  ss.stuff = GrowStuff;
+  ss.base = 0;
+  ss.cur = 0;
+  ss.maxlen = 0;
+  rv = dosprintf(&ss, aFmt, aAp);
+  if (rv < 0) {
+    if (ss.base) {
+      PR_DELETE(ss.base);
+    }
+    return 0;
+  }
+  return ss.base;
+}
+
+/*
+** Stuff routine that discards overflow data
+*/
+static int
+LimitStuff(SprintfState* aState, const char16_t* aStr, uint32_t aLen)
+{
+  uint32_t limit = aState->maxlen - (aState->cur - aState->base);
+
+  if (aLen > limit) {
+    aLen = limit;
+  }
+  while (aLen) {
+    --aLen;
+    *aState->cur++ = *aStr++;
+  }
+  return 0;
+}
+
+/*
+** sprintf into a fixed size buffer. Make sure there is a NUL at the end
+** when finished.
+*/
+uint32_t
+nsTextFormatter::snprintf(char16_t* aOut, uint32_t aOutLen,
+                          const char16_t* aFmt, ...)
+{
+  va_list ap;
+  uint32_t rv;
+
+  MOZ_ASSERT((int32_t)aOutLen > 0);
+  if ((int32_t)aOutLen <= 0) {
+    return 0;
+  }
+
+  va_start(ap, aFmt);
+  rv = nsTextFormatter::vsnprintf(aOut, aOutLen, aFmt, ap);
+  va_end(ap);
+  return rv;
+}
+
+uint32_t
+nsTextFormatter::vsnprintf(char16_t* aOut, uint32_t aOutLen,
+                           const char16_t* aFmt, va_list aAp)
+{
+  SprintfState ss;
+  uint32_t n;
+
+  MOZ_ASSERT((int32_t)aOutLen > 0);
+  if ((int32_t)aOutLen <= 0) {
+    return 0;
+  }
+
+  ss.stuff = LimitStuff;
+  ss.base = aOut;
+  ss.cur = aOut;
+  ss.maxlen = aOutLen;
+  (void) dosprintf(&ss, aFmt, aAp);
+
+  /* If we added chars, and we didn't append a null, do it now. */
+  if ((ss.cur != ss.base) && (*(ss.cur - 1) != '\0')) {
+    *(--ss.cur) = '\0';
+  }
+
+  n = ss.cur - ss.base;
+  return n ? n - 1 : n;
+}
+
+/*
+ * Free memory allocated, for the caller, by smprintf
+ */
+void
+nsTextFormatter::smprintf_free(char16_t* aMem)
+{
+  free(aMem);
+}
+
diff --git a/xpcom/glue/nsTextFormatter.h b/xpcom/glue/nsTextFormatter.h
new file mode 100644
index 000000000..4cd44be32
--- /dev/null
+++ b/xpcom/glue/nsTextFormatter.h
@@ -0,0 +1,80 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * This code was copied from xpcom/ds/nsTextFormatter r1.3
+ *           Memory model and Frozen linkage changes only.
+ *                           -- Prasad <prasad@medhas.org>
+ */
+
+#ifndef nsTextFormatter_h___
+#define nsTextFormatter_h___
+
+/*
+ ** API for PR printf like routines. Supports the following formats
+ **	%d - decimal
+ **	%u - unsigned decimal
+ **	%x - unsigned hex
+ **	%X - unsigned uppercase hex
+ **	%o - unsigned octal
+ **	%hd, %hu, %hx, %hX, %ho - 16-bit versions of above
+ **	%ld, %lu, %lx, %lX, %lo - 32-bit versions of above
+ **	%lld, %llu, %llx, %llX, %llo - 64 bit versions of above
+ **	%s - utf8 string
+ **	%S - char16_t string
+ **	%c - character
+ **	%p - pointer (deals with machine dependent pointer size)
+ **	%f - float
+ **	%g - float
+ */
+#include "prio.h"
+#include <stdio.h>
+#include <stdarg.h>
+#include "nscore.h"
+#include "nsStringGlue.h"
+
+#ifdef XPCOM_GLUE
+#error "nsTextFormatter is not available in the standalone glue due to NSPR dependencies."
+#endif
+
+class nsTextFormatter
+{
+public:
+
+  /*
+   * sprintf into a fixed size buffer. Guarantees that the buffer is null
+   * terminated. Returns the length of the written output, NOT including the
+   * null terminator, or (uint32_t)-1 if an error occurs.
+   */
+  static uint32_t snprintf(char16_t* aOut, uint32_t aOutLen,
+                           const char16_t* aFmt, ...);
+
+  /*
+   * sprintf into a moz_xmalloc'd buffer. Return a pointer to
+   * buffer on success, nullptr on failure.
+   */
+  static char16_t* smprintf(const char16_t* aFmt, ...);
+
+  static uint32_t ssprintf(nsAString& aOut, const char16_t* aFmt, ...);
+
+  /*
+   * va_list forms of the above.
+   */
+  static uint32_t vsnprintf(char16_t* aOut, uint32_t aOutLen, const char16_t* aFmt,
+                            va_list aAp);
+  static char16_t* vsmprintf(const char16_t* aFmt, va_list aAp);
+  static uint32_t vssprintf(nsAString& aOut, const char16_t* aFmt, va_list aAp);
+
+  /*
+   * Free the memory allocated, for the caller, by smprintf.
+   * -- Deprecated --
+   * Callers can substitute calling smprintf_free with free
+   */
+  static void smprintf_free(char16_t* aMem);
+
+};
+
+#endif /* nsTextFormatter_h___ */
diff --git a/xpcom/glue/nsThreadUtils.cpp b/xpcom/glue/nsThreadUtils.cpp
new file mode 100644
index 000000000..287ada7be
--- /dev/null
+++ b/xpcom/glue/nsThreadUtils.cpp
@@ -0,0 +1,472 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsThreadUtils.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Likely.h"
+#include "mozilla/TimeStamp.h"
+#include "LeakRefPtr.h"
+
+#ifdef MOZILLA_INTERNAL_API
+# include "nsThreadManager.h"
+#else
+# include "nsXPCOMCIDInternal.h"
+# include "nsIThreadManager.h"
+# include "nsServiceManagerUtils.h"
+#endif
+
+#ifdef XP_WIN
+#include <windows.h>
+#include "mozilla/WindowsVersion.h"
+using mozilla::IsVistaOrLater;
+#elif defined(XP_MACOSX)
+#include <sys/resource.h>
+#endif
+
+#include <pratom.h>
+#include <prthread.h>
+
+using namespace mozilla;
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+
+NS_IMPL_ISUPPORTS(IdlePeriod, nsIIdlePeriod)
+
+NS_IMETHODIMP
+IdlePeriod::GetIdlePeriodHint(TimeStamp* aIdleDeadline)
+{
+  *aIdleDeadline = TimeStamp();
+  return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS(Runnable, nsIRunnable)
+
+NS_IMETHODIMP
+Runnable::Run()
+{
+  // Do nothing
+  return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS_INHERITED(CancelableRunnable, Runnable,
+                            nsICancelableRunnable)
+
+nsresult
+CancelableRunnable::Cancel()
+{
+  // Do nothing
+  return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS_INHERITED(IncrementalRunnable, CancelableRunnable,
+                            nsIIncrementalRunnable)
+
+void
+IncrementalRunnable::SetDeadline(TimeStamp aDeadline)
+{
+  // Do nothing
+}
+
+#endif  // XPCOM_GLUE_AVOID_NSPR
+
+//-----------------------------------------------------------------------------
+
+nsresult
+NS_NewThread(nsIThread** aResult, nsIRunnable* aEvent, uint32_t aStackSize)
+{
+  nsCOMPtr<nsIThread> thread;
+#ifdef MOZILLA_INTERNAL_API
+  nsresult rv =
+    nsThreadManager::get().nsThreadManager::NewThread(0, aStackSize,
+                                                      getter_AddRefs(thread));
+#else
+  nsresult rv;
+  nsCOMPtr<nsIThreadManager> mgr =
+    do_GetService(NS_THREADMANAGER_CONTRACTID, &rv);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = mgr->NewThread(0, aStackSize, getter_AddRefs(thread));
+#endif
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  if (aEvent) {
+    rv = thread->Dispatch(aEvent, NS_DISPATCH_NORMAL);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+  *aResult = nullptr;
+  thread.swap(*aResult);
+  return NS_OK;
+}
+
+nsresult
+NS_GetCurrentThread(nsIThread** aResult)
+{
+#ifdef MOZILLA_INTERNAL_API
+  return nsThreadManager::get().nsThreadManager::GetCurrentThread(aResult);
+#else
+  nsresult rv;
+  nsCOMPtr<nsIThreadManager> mgr =
+    do_GetService(NS_THREADMANAGER_CONTRACTID, &rv);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+  return mgr->GetCurrentThread(aResult);
+#endif
+}
+
+nsresult
+NS_GetMainThread(nsIThread** aResult)
+{
+#ifdef MOZILLA_INTERNAL_API
+  return nsThreadManager::get().nsThreadManager::GetMainThread(aResult);
+#else
+  nsresult rv;
+  nsCOMPtr<nsIThreadManager> mgr =
+    do_GetService(NS_THREADMANAGER_CONTRACTID, &rv);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+  return mgr->GetMainThread(aResult);
+#endif
+}
+
+#ifndef MOZILLA_INTERNAL_API
+bool
+NS_IsMainThread()
+{
+  bool result = false;
+  nsCOMPtr<nsIThreadManager> mgr =
+    do_GetService(NS_THREADMANAGER_CONTRACTID);
+  if (mgr) {
+    mgr->GetIsMainThread(&result);
+  }
+  return bool(result);
+}
+#endif
+
+nsresult
+NS_DispatchToCurrentThread(already_AddRefed<nsIRunnable>&& aEvent)
+{
+  nsresult rv;
+  nsCOMPtr<nsIRunnable> event(aEvent);
+#ifdef MOZILLA_INTERNAL_API
+  nsIThread* thread = NS_GetCurrentThread();
+  if (!thread) {
+    return NS_ERROR_UNEXPECTED;
+  }
+#else
+  nsCOMPtr<nsIThread> thread;
+  rv = NS_GetCurrentThread(getter_AddRefs(thread));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+#endif
+  // To keep us from leaking the runnable if dispatch method fails,
+  // we grab the reference on failures and release it.
+  nsIRunnable* temp = event.get();
+  rv = thread->Dispatch(event.forget(), NS_DISPATCH_NORMAL);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    // Dispatch() leaked the reference to the event, but due to caller's
+    // assumptions, we shouldn't leak here. And given we are on the same
+    // thread as the dispatch target, it's mostly safe to do it here.
+    NS_RELEASE(temp);
+  }
+  return rv;
+}
+
+// It is common to call NS_DispatchToCurrentThread with a newly
+// allocated runnable with a refcount of zero. To keep us from leaking
+// the runnable if the dispatch method fails, we take a death grip.
+nsresult
+NS_DispatchToCurrentThread(nsIRunnable* aEvent)
+{
+  nsCOMPtr<nsIRunnable> event(aEvent);
+  return NS_DispatchToCurrentThread(event.forget());
+}
+
+nsresult
+NS_DispatchToMainThread(already_AddRefed<nsIRunnable>&& aEvent, uint32_t aDispatchFlags)
+{
+  LeakRefPtr<nsIRunnable> event(Move(aEvent));
+  nsCOMPtr<nsIThread> thread;
+  nsresult rv = NS_GetMainThread(getter_AddRefs(thread));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    NS_ASSERTION(false, "Failed NS_DispatchToMainThread() in shutdown; leaking");
+    // NOTE: if you stop leaking here, adjust Promise::MaybeReportRejected(),
+    // which assumes a leak here, or split into leaks and no-leaks versions
+    return rv;
+  }
+  return thread->Dispatch(event.take(), aDispatchFlags);
+}
+
+// In the case of failure with a newly allocated runnable with a
+// refcount of zero, we intentionally leak the runnable, because it is
+// likely that the runnable is being dispatched to the main thread
+// because it owns main thread only objects, so it is not safe to
+// release them here.
+nsresult
+NS_DispatchToMainThread(nsIRunnable* aEvent, uint32_t aDispatchFlags)
+{
+  nsCOMPtr<nsIRunnable> event(aEvent);
+  return NS_DispatchToMainThread(event.forget(), aDispatchFlags);
+}
+
+nsresult
+NS_DelayedDispatchToCurrentThread(already_AddRefed<nsIRunnable>&& aEvent, uint32_t aDelayMs)
+{
+  nsCOMPtr<nsIRunnable> event(aEvent);
+#ifdef MOZILLA_INTERNAL_API
+  nsIThread* thread = NS_GetCurrentThread();
+  if (!thread) {
+    return NS_ERROR_UNEXPECTED;
+  }
+#else
+  nsresult rv;
+  nsCOMPtr<nsIThread> thread;
+  rv = NS_GetCurrentThread(getter_AddRefs(thread));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+#endif
+
+  return thread->DelayedDispatch(event.forget(), aDelayMs);
+}
+
+nsresult
+NS_IdleDispatchToCurrentThread(already_AddRefed<nsIRunnable>&& aEvent)
+{
+  nsresult rv;
+  nsCOMPtr<nsIRunnable> event(aEvent);
+#ifdef MOZILLA_INTERNAL_API
+  nsIThread* thread = NS_GetCurrentThread();
+  if (!thread) {
+    return NS_ERROR_UNEXPECTED;
+  }
+#else
+  nsCOMPtr<nsIThread> thread;
+  rv = NS_GetCurrentThread(getter_AddRefs(thread));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+#endif
+  // To keep us from leaking the runnable if dispatch method fails,
+  // we grab the reference on failures and release it.
+  nsIRunnable* temp = event.get();
+  rv = thread->IdleDispatch(event.forget());
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    // Dispatch() leaked the reference to the event, but due to caller's
+    // assumptions, we shouldn't leak here. And given we are on the same
+    // thread as the dispatch target, it's mostly safe to do it here.
+    NS_RELEASE(temp);
+  }
+
+  return rv;
+}
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+nsresult
+NS_ProcessPendingEvents(nsIThread* aThread, PRIntervalTime aTimeout)
+{
+  nsresult rv = NS_OK;
+
+#ifdef MOZILLA_INTERNAL_API
+  if (!aThread) {
+    aThread = NS_GetCurrentThread();
+    if (NS_WARN_IF(!aThread)) {
+      return NS_ERROR_UNEXPECTED;
+    }
+  }
+#else
+  nsCOMPtr<nsIThread> current;
+  if (!aThread) {
+    rv = NS_GetCurrentThread(getter_AddRefs(current));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+    aThread = current.get();
+  }
+#endif
+
+  PRIntervalTime start = PR_IntervalNow();
+  for (;;) {
+    bool processedEvent;
+    rv = aThread->ProcessNextEvent(false, &processedEvent);
+    if (NS_FAILED(rv) || !processedEvent) {
+      break;
+    }
+    if (PR_IntervalNow() - start > aTimeout) {
+      break;
+    }
+  }
+  return rv;
+}
+#endif // XPCOM_GLUE_AVOID_NSPR
+
+inline bool
+hasPendingEvents(nsIThread* aThread)
+{
+  bool val;
+  return NS_SUCCEEDED(aThread->HasPendingEvents(&val)) && val;
+}
+
+bool
+NS_HasPendingEvents(nsIThread* aThread)
+{
+  if (!aThread) {
+#ifndef MOZILLA_INTERNAL_API
+    nsCOMPtr<nsIThread> current;
+    NS_GetCurrentThread(getter_AddRefs(current));
+    return hasPendingEvents(current);
+#else
+    aThread = NS_GetCurrentThread();
+    if (NS_WARN_IF(!aThread)) {
+      return false;
+    }
+#endif
+  }
+  return hasPendingEvents(aThread);
+}
+
+bool
+NS_ProcessNextEvent(nsIThread* aThread, bool aMayWait)
+{
+#ifdef MOZILLA_INTERNAL_API
+  if (!aThread) {
+    aThread = NS_GetCurrentThread();
+    if (NS_WARN_IF(!aThread)) {
+      return false;
+    }
+  }
+#else
+  nsCOMPtr<nsIThread> current;
+  if (!aThread) {
+    NS_GetCurrentThread(getter_AddRefs(current));
+    if (NS_WARN_IF(!current)) {
+      return false;
+    }
+    aThread = current.get();
+  }
+#endif
+  bool val;
+  return NS_SUCCEEDED(aThread->ProcessNextEvent(aMayWait, &val)) && val;
+}
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+
+namespace {
+
+class nsNameThreadRunnable final : public nsIRunnable
+{
+  ~nsNameThreadRunnable() {}
+
+public:
+  explicit nsNameThreadRunnable(const nsACString& aName) : mName(aName) {}
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIRUNNABLE
+
+protected:
+  const nsCString mName;
+};
+
+NS_IMPL_ISUPPORTS(nsNameThreadRunnable, nsIRunnable)
+
+NS_IMETHODIMP
+nsNameThreadRunnable::Run()
+{
+  PR_SetCurrentThreadName(mName.BeginReading());
+  return NS_OK;
+}
+
+} // namespace
+
+void
+NS_SetThreadName(nsIThread* aThread, const nsACString& aName)
+{
+  if (!aThread) {
+    return;
+  }
+
+  aThread->Dispatch(new nsNameThreadRunnable(aName),
+                    nsIEventTarget::DISPATCH_NORMAL);
+}
+
+#else // !XPCOM_GLUE_AVOID_NSPR
+
+void
+NS_SetThreadName(nsIThread* aThread, const nsACString& aName)
+{
+  // No NSPR, no love.
+}
+
+#endif
+
+#ifdef MOZILLA_INTERNAL_API
+nsIThread*
+NS_GetCurrentThread()
+{
+  return nsThreadManager::get().GetCurrentThread();
+}
+#endif
+
+// nsThreadPoolNaming
+void
+nsThreadPoolNaming::SetThreadPoolName(const nsACString& aPoolName,
+                                      nsIThread* aThread)
+{
+  nsCString name(aPoolName);
+  name.AppendLiteral(" #");
+  name.AppendInt(++mCounter, 10); // The counter is declared as volatile
+
+  if (aThread) {
+    // Set on the target thread
+    NS_SetThreadName(aThread, name);
+  } else {
+    // Set on the current thread
+#ifndef XPCOM_GLUE_AVOID_NSPR
+    PR_SetCurrentThreadName(name.BeginReading());
+#endif
+  }
+}
+
+// nsAutoLowPriorityIO
+nsAutoLowPriorityIO::nsAutoLowPriorityIO()
+{
+#if defined(XP_WIN)
+  lowIOPrioritySet = IsVistaOrLater() &&
+                     SetThreadPriority(GetCurrentThread(),
+                                       THREAD_MODE_BACKGROUND_BEGIN);
+#elif defined(XP_MACOSX)
+  oldPriority = getiopolicy_np(IOPOL_TYPE_DISK, IOPOL_SCOPE_THREAD);
+  lowIOPrioritySet = oldPriority != -1 &&
+                     setiopolicy_np(IOPOL_TYPE_DISK,
+                                    IOPOL_SCOPE_THREAD,
+                                    IOPOL_THROTTLE) != -1;
+#else
+  lowIOPrioritySet = false;
+#endif
+}
+
+nsAutoLowPriorityIO::~nsAutoLowPriorityIO()
+{
+#if defined(XP_WIN)
+  if (MOZ_LIKELY(lowIOPrioritySet)) {
+    // On Windows the old thread priority is automatically restored
+    SetThreadPriority(GetCurrentThread(), THREAD_MODE_BACKGROUND_END);
+  }
+#elif defined(XP_MACOSX)
+  if (MOZ_LIKELY(lowIOPrioritySet)) {
+    setiopolicy_np(IOPOL_TYPE_DISK, IOPOL_SCOPE_THREAD, oldPriority);
+  }
+#endif
+}
diff --git a/xpcom/glue/nsThreadUtils.h b/xpcom/glue/nsThreadUtils.h
new file mode 100644
index 000000000..cbd7f7842
--- /dev/null
+++ b/xpcom/glue/nsThreadUtils.h
@@ -0,0 +1,1049 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsThreadUtils_h__
+#define nsThreadUtils_h__
+
+#include "prthread.h"
+#include "prinrval.h"
+#include "MainThreadUtils.h"
+#include "nsIThreadManager.h"
+#include "nsIThread.h"
+#include "nsIRunnable.h"
+#include "nsICancelableRunnable.h"
+#include "nsIIdlePeriod.h"
+#include "nsIIncrementalRunnable.h"
+#include "nsStringGlue.h"
+#include "nsCOMPtr.h"
+#include "nsAutoPtr.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/IndexSequence.h"
+#include "mozilla/Likely.h"
+#include "mozilla/Move.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/Tuple.h"
+#include "mozilla/TypeTraits.h"
+
+//-----------------------------------------------------------------------------
+// These methods are alternatives to the methods on nsIThreadManager, provided
+// for convenience.
+
+/**
+ * Set name of the target thread.  This operation is asynchronous.
+ */
+extern void NS_SetThreadName(nsIThread* aThread, const nsACString& aName);
+
+/**
+ * Static length version of the above function checking length of the
+ * name at compile time.
+ */
+template<size_t LEN>
+inline void
+NS_SetThreadName(nsIThread* aThread, const char (&aName)[LEN])
+{
+  static_assert(LEN <= 16,
+                "Thread name must be no more than 16 characters");
+  NS_SetThreadName(aThread, nsDependentCString(aName));
+}
+
+/**
+ * Create a new thread, and optionally provide an initial event for the thread.
+ *
+ * @param aResult
+ *   The resulting nsIThread object.
+ * @param aInitialEvent
+ *   The initial event to run on this thread.  This parameter may be null.
+ * @param aStackSize
+ *   The size in bytes to reserve for the thread's stack.
+ *
+ * @returns NS_ERROR_INVALID_ARG
+ *   Indicates that the given name is not unique.
+ */
+extern nsresult
+NS_NewThread(nsIThread** aResult,
+             nsIRunnable* aInitialEvent = nullptr,
+             uint32_t aStackSize = nsIThreadManager::DEFAULT_STACK_SIZE);
+
+/**
+ * Creates a named thread, otherwise the same as NS_NewThread
+ */
+template<size_t LEN>
+inline nsresult
+NS_NewNamedThread(const char (&aName)[LEN],
+                  nsIThread** aResult,
+                  nsIRunnable* aInitialEvent = nullptr,
+                  uint32_t aStackSize = nsIThreadManager::DEFAULT_STACK_SIZE)
+{
+  // Hold a ref while dispatching the initial event to match NS_NewThread()
+  nsCOMPtr<nsIThread> thread;
+  nsresult rv = NS_NewThread(getter_AddRefs(thread), nullptr, aStackSize);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+  NS_SetThreadName<LEN>(thread, aName);
+  if (aInitialEvent) {
+    rv = thread->Dispatch(aInitialEvent, NS_DISPATCH_NORMAL);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "Initial event dispatch failed");
+  }
+
+  *aResult = nullptr;
+  thread.swap(*aResult);
+  return rv;
+}
+
+/**
+ * Get a reference to the current thread.
+ *
+ * @param aResult
+ *   The resulting nsIThread object.
+ */
+extern nsresult NS_GetCurrentThread(nsIThread** aResult);
+
+/**
+ * Dispatch the given event to the current thread.
+ *
+ * @param aEvent
+ *   The event to dispatch.
+ *
+ * @returns NS_ERROR_INVALID_ARG
+ *   If event is null.
+ */
+extern nsresult NS_DispatchToCurrentThread(nsIRunnable* aEvent);
+extern nsresult
+NS_DispatchToCurrentThread(already_AddRefed<nsIRunnable>&& aEvent);
+
+/**
+ * Dispatch the given event to the main thread.
+ *
+ * @param aEvent
+ *   The event to dispatch.
+ * @param aDispatchFlags
+ *   The flags to pass to the main thread's dispatch method.
+ *
+ * @returns NS_ERROR_INVALID_ARG
+ *   If event is null.
+ */
+extern nsresult
+NS_DispatchToMainThread(nsIRunnable* aEvent,
+                        uint32_t aDispatchFlags = NS_DISPATCH_NORMAL);
+extern nsresult
+NS_DispatchToMainThread(already_AddRefed<nsIRunnable>&& aEvent,
+                        uint32_t aDispatchFlags = NS_DISPATCH_NORMAL);
+
+extern nsresult
+NS_DelayedDispatchToCurrentThread(
+  already_AddRefed<nsIRunnable>&& aEvent, uint32_t aDelayMs);
+
+extern nsresult
+NS_IdleDispatchToCurrentThread(already_AddRefed<nsIRunnable>&& aEvent);
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+/**
+ * Process all pending events for the given thread before returning.  This
+ * method simply calls ProcessNextEvent on the thread while HasPendingEvents
+ * continues to return true and the time spent in NS_ProcessPendingEvents
+ * does not exceed the given timeout value.
+ *
+ * @param aThread
+ *   The thread object for which to process pending events.  If null, then
+ *   events will be processed for the current thread.
+ * @param aTimeout
+ *   The maximum number of milliseconds to spend processing pending events.
+ *   Events are not pre-empted to honor this timeout.  Rather, the timeout
+ *   value is simply used to determine whether or not to process another event.
+ *   Pass PR_INTERVAL_NO_TIMEOUT to specify no timeout.
+ */
+extern nsresult
+NS_ProcessPendingEvents(nsIThread* aThread,
+                        PRIntervalTime aTimeout = PR_INTERVAL_NO_TIMEOUT);
+#endif
+
+/**
+ * Shortcut for nsIThread::HasPendingEvents.
+ *
+ * It is an error to call this function when the given thread is not the
+ * current thread.  This function will return false if called from some
+ * other thread.
+ *
+ * @param aThread
+ *   The current thread or null.
+ *
+ * @returns
+ *   A boolean value that if "true" indicates that there are pending events
+ *   in the current thread's event queue.
+ */
+extern bool NS_HasPendingEvents(nsIThread* aThread = nullptr);
+
+/**
+ * Shortcut for nsIThread::ProcessNextEvent.
+ *
+ * It is an error to call this function when the given thread is not the
+ * current thread.  This function will simply return false if called
+ * from some other thread.
+ *
+ * @param aThread
+ *   The current thread or null.
+ * @param aMayWait
+ *   A boolean parameter that if "true" indicates that the method may block
+ *   the calling thread to wait for a pending event.
+ *
+ * @returns
+ *   A boolean value that if "true" indicates that an event from the current
+ *   thread's event queue was processed.
+ */
+extern bool NS_ProcessNextEvent(nsIThread* aThread = nullptr,
+                                bool aMayWait = true);
+
+//-----------------------------------------------------------------------------
+// Helpers that work with nsCOMPtr:
+
+inline already_AddRefed<nsIThread>
+do_GetCurrentThread()
+{
+  nsIThread* thread = nullptr;
+  NS_GetCurrentThread(&thread);
+  return already_AddRefed<nsIThread>(thread);
+}
+
+inline already_AddRefed<nsIThread>
+do_GetMainThread()
+{
+  nsIThread* thread = nullptr;
+  NS_GetMainThread(&thread);
+  return already_AddRefed<nsIThread>(thread);
+}
+
+//-----------------------------------------------------------------------------
+
+#ifdef MOZILLA_INTERNAL_API
+// Fast access to the current thread.  Do not release the returned pointer!  If
+// you want to use this pointer from some other thread, then you will need to
+// AddRef it.  Otherwise, you should only consider this pointer valid from code
+// running on the current thread.
+extern nsIThread* NS_GetCurrentThread();
+#endif
+
+//-----------------------------------------------------------------------------
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+
+namespace mozilla {
+
+// This class is designed to be subclassed.
+class IdlePeriod : public nsIIdlePeriod
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIIDLEPERIOD
+
+  IdlePeriod() {}
+
+protected:
+  virtual ~IdlePeriod() {}
+private:
+  IdlePeriod(const IdlePeriod&) = delete;
+  IdlePeriod& operator=(const IdlePeriod&) = delete;
+  IdlePeriod& operator=(const IdlePeriod&&) = delete;
+};
+
+// This class is designed to be subclassed.
+class Runnable : public nsIRunnable
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIRUNNABLE
+
+  Runnable() {}
+
+protected:
+  virtual ~Runnable() {}
+private:
+  Runnable(const Runnable&) = delete;
+  Runnable& operator=(const Runnable&) = delete;
+  Runnable& operator=(const Runnable&&) = delete;
+};
+
+// This class is designed to be subclassed.
+class CancelableRunnable : public Runnable,
+                           public nsICancelableRunnable
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  // nsICancelableRunnable
+  virtual nsresult Cancel() override;
+
+  CancelableRunnable() {}
+
+protected:
+  virtual ~CancelableRunnable() {}
+private:
+  CancelableRunnable(const CancelableRunnable&) = delete;
+  CancelableRunnable& operator=(const CancelableRunnable&) = delete;
+  CancelableRunnable& operator=(const CancelableRunnable&&) = delete;
+};
+
+// This class is designed to be subclassed.
+class IncrementalRunnable : public CancelableRunnable,
+                            public nsIIncrementalRunnable
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  // nsIIncrementalRunnable
+  virtual void SetDeadline(TimeStamp aDeadline) override;
+
+  IncrementalRunnable() {}
+
+protected:
+  virtual ~IncrementalRunnable() {}
+private:
+  IncrementalRunnable(const IncrementalRunnable&) = delete;
+  IncrementalRunnable& operator=(const IncrementalRunnable&) = delete;
+  IncrementalRunnable& operator=(const IncrementalRunnable&&) = delete;
+};
+
+namespace detail {
+
+// An event that can be used to call a C++11 functions or function objects,
+// including lambdas. The function must have no required arguments, and must
+// return void.
+template<typename StoredFunction>
+class RunnableFunction : public Runnable
+{
+public:
+  template <typename F>
+  explicit RunnableFunction(F&& aFunction)
+    : mFunction(Forward<F>(aFunction))
+  { }
+
+  NS_IMETHOD Run() override {
+    static_assert(IsVoid<decltype(mFunction())>::value,
+                  "The lambda must return void!");
+    mFunction();
+    return NS_OK;
+  }
+private:
+  StoredFunction mFunction;
+};
+
+} // namespace detail
+
+} // namespace mozilla
+
+template<typename Function>
+already_AddRefed<mozilla::Runnable>
+NS_NewRunnableFunction(Function&& aFunction)
+{
+  return do_AddRef(new mozilla::detail::RunnableFunction
+                   // Make sure we store a non-reference in nsRunnableFunction.
+                   <typename mozilla::RemoveReference<Function>::Type>
+                   // But still forward aFunction to move if possible.
+                   (mozilla::Forward<Function>(aFunction)));
+}
+
+// An event that can be used to call a method on a class.  The class type must
+// support reference counting. This event supports Revoke for use
+// with nsRevocableEventPtr.
+template<class ClassType,
+         typename ReturnType = void,
+         bool Owning = true,
+         bool Cancelable = false>
+class nsRunnableMethod : public mozilla::Conditional<!Cancelable,
+                                                     mozilla::Runnable,
+                                                     mozilla::CancelableRunnable>::Type
+{
+public:
+  virtual void Revoke() = 0;
+
+  // These ReturnTypeEnforcer classes set up a blacklist for return types that
+  // we know are not safe. The default ReturnTypeEnforcer compiles just fine but
+  // already_AddRefed will not.
+  template<typename OtherReturnType>
+  class ReturnTypeEnforcer
+  {
+  public:
+    typedef int ReturnTypeIsSafe;
+  };
+
+  template<class T>
+  class ReturnTypeEnforcer<already_AddRefed<T>>
+  {
+    // No ReturnTypeIsSafe makes this illegal!
+  };
+
+  // Make sure this return type is safe.
+  typedef typename ReturnTypeEnforcer<ReturnType>::ReturnTypeIsSafe check;
+};
+
+template<class ClassType, bool Owning>
+struct nsRunnableMethodReceiver
+{
+  RefPtr<ClassType> mObj;
+  explicit nsRunnableMethodReceiver(ClassType* aObj) : mObj(aObj) {}
+  ~nsRunnableMethodReceiver() { Revoke(); }
+  ClassType* Get() const { return mObj.get(); }
+  void Revoke() { mObj = nullptr; }
+};
+
+template<class ClassType>
+struct nsRunnableMethodReceiver<ClassType, false>
+{
+  ClassType* MOZ_NON_OWNING_REF mObj;
+  explicit nsRunnableMethodReceiver(ClassType* aObj) : mObj(aObj) {}
+  ClassType* Get() const { return mObj; }
+  void Revoke() { mObj = nullptr; }
+};
+
+template<typename Method, bool Owning, bool Cancelable> struct nsRunnableMethodTraits;
+
+template<class C, typename R, bool Owning, bool Cancelable, typename... As>
+struct nsRunnableMethodTraits<R(C::*)(As...), Owning, Cancelable>
+{
+  typedef C class_type;
+  typedef R return_type;
+  typedef nsRunnableMethod<C, R, Owning, Cancelable> base_type;
+  static const bool can_cancel = Cancelable;
+};
+
+template<class C, typename R, bool Owning, bool Cancelable, typename... As>
+struct nsRunnableMethodTraits<R(C::*)(As...) const, Owning, Cancelable>
+{
+  typedef const C class_type;
+  typedef R return_type;
+  typedef nsRunnableMethod<C, R, Owning, Cancelable> base_type;
+  static const bool can_cancel = Cancelable;
+};
+
+#ifdef NS_HAVE_STDCALL
+template<class C, typename R, bool Owning, bool Cancelable, typename... As>
+struct nsRunnableMethodTraits<R(__stdcall C::*)(As...), Owning, Cancelable>
+{
+  typedef C class_type;
+  typedef R return_type;
+  typedef nsRunnableMethod<C, R, Owning, Cancelable> base_type;
+  static const bool can_cancel = Cancelable;
+};
+
+template<class C, typename R, bool Owning, bool Cancelable>
+struct nsRunnableMethodTraits<R(NS_STDCALL C::*)(), Owning, Cancelable>
+{
+  typedef C class_type;
+  typedef R return_type;
+  typedef nsRunnableMethod<C, R, Owning, Cancelable> base_type;
+  static const bool can_cancel = Cancelable;
+};
+template<class C, typename R, bool Owning, bool Cancelable, typename... As>
+struct nsRunnableMethodTraits<R(__stdcall C::*)(As...) const, Owning, Cancelable>
+{
+  typedef const C class_type;
+  typedef R return_type;
+  typedef nsRunnableMethod<C, R, Owning, Cancelable> base_type;
+  static const bool can_cancel = Cancelable;
+};
+
+template<class C, typename R, bool Owning, bool Cancelable>
+struct nsRunnableMethodTraits<R(NS_STDCALL C::*)() const, Owning, Cancelable>
+{
+  typedef const C class_type;
+  typedef R return_type;
+  typedef nsRunnableMethod<C, R, Owning, Cancelable> base_type;
+  static const bool can_cancel = Cancelable;
+};
+#endif
+
+
+// IsParameterStorageClass<T>::value is true if T is a parameter-storage class
+// that will be recognized by NS_New[NonOwning]RunnableMethodWithArg[s] to
+// force a specific storage&passing strategy (instead of inferring one,
+// see ParameterStorage).
+// When creating a new storage class, add a specialization for it to be
+// recognized.
+template<typename T>
+struct IsParameterStorageClass : public mozilla::FalseType {};
+
+// StoreXPassByY structs used to inform nsRunnableMethodArguments how to
+// store arguments, and how to pass them to the target method.
+
+template<typename T>
+struct StoreCopyPassByValue
+{
+  typedef T stored_type;
+  typedef T passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreCopyPassByValue(A&& a) : m(mozilla::Forward<A>(a)) {}
+  passed_type PassAsParameter() { return m; }
+};
+template<typename S>
+struct IsParameterStorageClass<StoreCopyPassByValue<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StoreCopyPassByConstLRef
+{
+  typedef T stored_type;
+  typedef const T& passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreCopyPassByConstLRef(A&& a) : m(mozilla::Forward<A>(a)) {}
+  passed_type PassAsParameter() { return m; }
+};
+template<typename S>
+struct IsParameterStorageClass<StoreCopyPassByConstLRef<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StoreCopyPassByLRef
+{
+  typedef T stored_type;
+  typedef T& passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreCopyPassByLRef(A&& a) : m(mozilla::Forward<A>(a)) {}
+  passed_type PassAsParameter() { return m; }
+};
+template<typename S>
+struct IsParameterStorageClass<StoreCopyPassByLRef<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StoreCopyPassByRRef
+{
+  typedef T stored_type;
+  typedef T&& passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreCopyPassByRRef(A&& a) : m(mozilla::Forward<A>(a)) {}
+  passed_type PassAsParameter() { return mozilla::Move(m); }
+};
+template<typename S>
+struct IsParameterStorageClass<StoreCopyPassByRRef<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StoreRefPassByLRef
+{
+  typedef T& stored_type;
+  typedef T& passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreRefPassByLRef(A& a) : m(a) {}
+  passed_type PassAsParameter() { return m; }
+};
+template<typename S>
+struct IsParameterStorageClass<StoreRefPassByLRef<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StoreConstRefPassByConstLRef
+{
+  typedef const T& stored_type;
+  typedef const T& passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreConstRefPassByConstLRef(const A& a) : m(a) {}
+  passed_type PassAsParameter() { return m; }
+};
+template<typename S>
+struct IsParameterStorageClass<StoreConstRefPassByConstLRef<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StorensRefPtrPassByPtr
+{
+  typedef RefPtr<T> stored_type;
+  typedef T* passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StorensRefPtrPassByPtr(A&& a) : m(mozilla::Forward<A>(a)) {}
+  passed_type PassAsParameter() { return m.get(); }
+};
+template<typename S>
+struct IsParameterStorageClass<StorensRefPtrPassByPtr<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StorePtrPassByPtr
+{
+  typedef T* stored_type;
+  typedef T* passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StorePtrPassByPtr(A a) : m(a) {}
+  passed_type PassAsParameter() { return m; }
+};
+template<typename S>
+struct IsParameterStorageClass<StorePtrPassByPtr<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StoreConstPtrPassByConstPtr
+{
+  typedef const T* stored_type;
+  typedef const T* passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreConstPtrPassByConstPtr(A a) : m(a) {}
+  passed_type PassAsParameter() { return m; }
+};
+template<typename S>
+struct IsParameterStorageClass<StoreConstPtrPassByConstPtr<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StoreCopyPassByConstPtr
+{
+  typedef T stored_type;
+  typedef const T* passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreCopyPassByConstPtr(A&& a) : m(mozilla::Forward<A>(a)) {}
+  passed_type PassAsParameter() { return &m; }
+};
+template<typename S>
+struct IsParameterStorageClass<StoreCopyPassByConstPtr<S>>
+  : public mozilla::TrueType {};
+
+template<typename T>
+struct StoreCopyPassByPtr
+{
+  typedef T stored_type;
+  typedef T* passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreCopyPassByPtr(A&& a) : m(mozilla::Forward<A>(a)) {}
+  passed_type PassAsParameter() { return &m; }
+};
+template<typename S>
+struct IsParameterStorageClass<StoreCopyPassByPtr<S>>
+  : public mozilla::TrueType {};
+
+namespace detail {
+
+template<typename TWithoutPointer>
+struct NonnsISupportsPointerStorageClass
+  : mozilla::Conditional<mozilla::IsConst<TWithoutPointer>::value,
+                         StoreConstPtrPassByConstPtr<
+                           typename mozilla::RemoveConst<TWithoutPointer>::Type>,
+                         StorePtrPassByPtr<TWithoutPointer>>
+{};
+
+template<typename>
+struct SFINAE1True : mozilla::TrueType
+{};
+
+template<class T>
+static auto HasRefCountMethodsTest(int)
+    -> SFINAE1True<decltype(mozilla::DeclVal<T>().AddRef(),
+                            mozilla::DeclVal<T>().Release())>;
+template<class>
+static auto HasRefCountMethodsTest(long) -> mozilla::FalseType;
+
+template<class T>
+struct HasRefCountMethods : decltype(HasRefCountMethodsTest<T>(0))
+{};
+
+template<typename T>
+struct IsRefcountedSmartPointer : public mozilla::FalseType
+{};
+
+template<typename T>
+struct IsRefcountedSmartPointer<RefPtr<T>> : public mozilla::TrueType
+{};
+
+template<typename T>
+struct IsRefcountedSmartPointer<nsCOMPtr<T>> : public mozilla::TrueType
+{};
+
+template<typename T>
+struct StripSmartPointer
+{
+  typedef void Type;
+};
+
+template<typename T>
+struct StripSmartPointer<RefPtr<T>>
+{
+  typedef T Type;
+};
+
+template<typename T>
+struct StripSmartPointer<nsCOMPtr<T>>
+{
+  typedef T Type;
+};
+
+template<typename TWithoutPointer>
+struct PointerStorageClass
+  : mozilla::Conditional<HasRefCountMethods<TWithoutPointer>::value,
+                         StorensRefPtrPassByPtr<TWithoutPointer>,
+                         typename NonnsISupportsPointerStorageClass<
+                           TWithoutPointer
+                         >::Type>
+{};
+
+template<typename TWithoutRef>
+struct LValueReferenceStorageClass
+  : mozilla::Conditional<mozilla::IsConst<TWithoutRef>::value,
+                         StoreConstRefPassByConstLRef<
+                           typename mozilla::RemoveConst<TWithoutRef>::Type>,
+                         StoreRefPassByLRef<TWithoutRef>>
+{};
+
+template<typename T>
+struct SmartPointerStorageClass
+  : mozilla::Conditional<IsRefcountedSmartPointer<T>::value,
+                         StorensRefPtrPassByPtr<
+                           typename StripSmartPointer<T>::Type>,
+                         StoreCopyPassByValue<T>>
+{};
+
+template<typename T>
+struct NonLValueReferenceStorageClass
+  : mozilla::Conditional<mozilla::IsRvalueReference<T>::value,
+                         StoreCopyPassByRRef<
+                           typename mozilla::RemoveReference<T>::Type>,
+                         typename SmartPointerStorageClass<T>::Type>
+{};
+
+template<typename T>
+struct NonPointerStorageClass
+  : mozilla::Conditional<mozilla::IsLvalueReference<T>::value,
+                         typename LValueReferenceStorageClass<
+                           typename mozilla::RemoveReference<T>::Type
+                         >::Type,
+                         typename NonLValueReferenceStorageClass<T>::Type>
+{};
+
+template<typename T>
+struct NonParameterStorageClass
+  : mozilla::Conditional<mozilla::IsPointer<T>::value,
+                         typename PointerStorageClass<
+                           typename mozilla::RemovePointer<T>::Type
+                         >::Type,
+                         typename NonPointerStorageClass<T>::Type>
+{};
+
+// Choose storage&passing strategy based on preferred storage type:
+// - If IsParameterStorageClass<T>::value is true, use as-is.
+// - RC*       -> StorensRefPtrPassByPtr<RC>     : Store RefPtr<RC>, pass RC*
+//   ^^ RC quacks like a ref-counted type (i.e., has AddRef and Release methods)
+// - const T*  -> StoreConstPtrPassByConstPtr<T> : Store const T*, pass const T*
+// - T*        -> StorePtrPassByPtr<T>           : Store T*, pass T*.
+// - const T&  -> StoreConstRefPassByConstLRef<T>: Store const T&, pass const T&.
+// - T&        -> StoreRefPassByLRef<T>          : Store T&, pass T&.
+// - T&&       -> StoreCopyPassByRRef<T>         : Store T, pass Move(T).
+// - RefPtr<T>, nsCOMPtr<T>
+//             -> StorensRefPtrPassByPtr<T>      : Store RefPtr<T>, pass T*
+// - Other T   -> StoreCopyPassByValue<T>        : Store T, pass T.
+// Other available explicit options:
+// -              StoreCopyPassByConstLRef<T>    : Store T, pass const T&.
+// -              StoreCopyPassByLRef<T>         : Store T, pass T& (of copy!)
+// -              StoreCopyPassByConstPtr<T>     : Store T, pass const T*
+// -              StoreCopyPassByPtr<T>          : Store T, pass T* (of copy!)
+// Or create your own class with PassAsParameter() method, optional
+// clean-up in destructor, and with associated IsParameterStorageClass<>.
+template<typename T>
+struct ParameterStorage
+  : mozilla::Conditional<IsParameterStorageClass<T>::value,
+                         T,
+                         typename NonParameterStorageClass<T>::Type>
+{};
+
+} /* namespace detail */
+
+namespace mozilla {
+
+namespace detail {
+
+// struct used to store arguments and later apply them to a method.
+template <typename... Ts>
+struct RunnableMethodArguments final
+{
+  Tuple<typename ::detail::ParameterStorage<Ts>::Type...> mArguments;
+  template <typename... As>
+  explicit RunnableMethodArguments(As&&... aArguments)
+    : mArguments(Forward<As>(aArguments)...)
+  {}
+  template<typename C, typename M, typename... Args, size_t... Indices>
+  static auto
+  applyImpl(C* o, M m, Tuple<Args...>& args, IndexSequence<Indices...>)
+      -> decltype(((*o).*m)(Get<Indices>(args).PassAsParameter()...))
+  {
+    return ((*o).*m)(Get<Indices>(args).PassAsParameter()...);
+  }
+  template<class C, typename M> auto apply(C* o, M m)
+      -> decltype(applyImpl(o, m, mArguments,
+                  typename IndexSequenceFor<Ts...>::Type()))
+  {
+    return applyImpl(o, m, mArguments,
+        typename IndexSequenceFor<Ts...>::Type());
+  }
+};
+
+template<typename Method, bool Owning, bool Cancelable, typename... Storages>
+class RunnableMethodImpl final
+  : public ::nsRunnableMethodTraits<Method, Owning, Cancelable>::base_type
+{
+  typedef typename ::nsRunnableMethodTraits<Method, Owning, Cancelable>::class_type
+      ClassType;
+  ::nsRunnableMethodReceiver<ClassType, Owning> mReceiver;
+  Method mMethod;
+  RunnableMethodArguments<Storages...> mArgs;
+private:
+  virtual ~RunnableMethodImpl() { Revoke(); };
+public:
+  template<typename... Args>
+  explicit RunnableMethodImpl(ClassType* aObj, Method aMethod,
+                              Args&&... aArgs)
+    : mReceiver(aObj)
+    , mMethod(aMethod)
+    , mArgs(Forward<Args>(aArgs)...)
+  {
+    static_assert(sizeof...(Storages) == sizeof...(Args), "Storages and Args should have equal sizes");
+  }
+  NS_IMETHOD Run()
+  {
+    if (MOZ_LIKELY(mReceiver.Get())) {
+      mArgs.apply(mReceiver.Get(), mMethod);
+    }
+    return NS_OK;
+  }
+  nsresult Cancel() {
+    static_assert(Cancelable, "Don't use me!");
+    Revoke();
+    return NS_OK;
+  }
+  void Revoke() { mReceiver.Revoke(); }
+};
+
+} // namespace detail
+
+// Use this template function like so:
+//
+//   nsCOMPtr<nsIRunnable> event =
+//     mozilla::NewRunnableMethod(myObject, &MyClass::HandleEvent);
+//   NS_DispatchToCurrentThread(event);
+//
+// Statically enforced constraints:
+//  - myObject must be of (or implicitly convertible to) type MyClass
+//  - MyClass must define AddRef and Release methods
+//
+
+template<typename PtrType, typename Method>
+already_AddRefed<typename ::nsRunnableMethodTraits<Method, true, false>::base_type>
+NewRunnableMethod(PtrType aPtr, Method aMethod)
+{
+  return do_AddRef(new detail::RunnableMethodImpl<Method, true, false>(aPtr, aMethod));
+}
+
+template<typename PtrType, typename Method>
+already_AddRefed<typename ::nsRunnableMethodTraits<Method, true, true>::base_type>
+NewCancelableRunnableMethod(PtrType aPtr, Method aMethod)
+{
+  return do_AddRef(new detail::RunnableMethodImpl<Method, true, true>(aPtr, aMethod));
+}
+
+template<typename PtrType, typename Method>
+already_AddRefed<typename ::nsRunnableMethodTraits<Method, false, false>::base_type>
+NewNonOwningRunnableMethod(PtrType&& aPtr, Method aMethod)
+{
+  return do_AddRef(new detail::RunnableMethodImpl<Method, false, false>(aPtr, aMethod));
+}
+
+template<typename PtrType, typename Method>
+already_AddRefed<typename ::nsRunnableMethodTraits<Method, false, true>::base_type>
+NewNonOwningCancelableRunnableMethod(PtrType&& aPtr, Method aMethod)
+{
+  return do_AddRef(new detail::RunnableMethodImpl<Method, false, true>(aPtr, aMethod));
+}
+
+// Similar to NewRunnableMethod. Call like so:
+// nsCOMPtr<nsIRunnable> event =
+//   NewRunnableMethod<Types,...>(myObject, &MyClass::HandleEvent, myArg1,...);
+// 'Types' are the stored type for each argument, see ParameterStorage for details.
+template<typename... Storages, typename Method, typename PtrType, typename... Args>
+already_AddRefed<typename ::nsRunnableMethodTraits<Method, true, false>::base_type>
+NewRunnableMethod(PtrType&& aPtr, Method aMethod, Args&&... aArgs)
+{
+  static_assert(sizeof...(Storages) == sizeof...(Args),
+                "<Storages...> size should be equal to number of arguments");
+  return do_AddRef(new detail::RunnableMethodImpl<Method, true, false, Storages...>(
+      aPtr, aMethod, mozilla::Forward<Args>(aArgs)...));
+}
+
+template<typename... Storages, typename Method, typename PtrType, typename... Args>
+already_AddRefed<typename ::nsRunnableMethodTraits<Method, false, false>::base_type>
+NewNonOwningRunnableMethod(PtrType&& aPtr, Method aMethod, Args&&... aArgs)
+{
+  static_assert(sizeof...(Storages) == sizeof...(Args),
+                "<Storages...> size should be equal to number of arguments");
+  return do_AddRef(new detail::RunnableMethodImpl<Method, false, false, Storages...>(
+      aPtr, aMethod, mozilla::Forward<Args>(aArgs)...));
+}
+
+template<typename... Storages, typename Method, typename PtrType, typename... Args>
+already_AddRefed<typename ::nsRunnableMethodTraits<Method, true, true>::base_type>
+NewCancelableRunnableMethod(PtrType&& aPtr, Method aMethod, Args&&... aArgs)
+{
+  static_assert(sizeof...(Storages) == sizeof...(Args),
+                "<Storages...> size should be equal to number of arguments");
+  return do_AddRef(new detail::RunnableMethodImpl<Method, true, true, Storages...>(
+      aPtr, aMethod, mozilla::Forward<Args>(aArgs)...));
+}
+
+template<typename... Storages, typename Method, typename PtrType, typename... Args>
+already_AddRefed<typename ::nsRunnableMethodTraits<Method, false, true>::base_type>
+NewNonOwningCancelableRunnableMethod(PtrType&& aPtr, Method aMethod,
+                                                Args&&... aArgs)
+{
+  static_assert(sizeof...(Storages) == sizeof...(Args),
+                "<Storages...> size should be equal to number of arguments");
+  return do_AddRef(new detail::RunnableMethodImpl<Method, false, true, Storages...>(
+      aPtr, aMethod, mozilla::Forward<Args>(aArgs)...));
+}
+
+} // namespace mozilla
+
+#endif  // XPCOM_GLUE_AVOID_NSPR
+
+// This class is designed to be used when you have an event class E that has a
+// pointer back to resource class R.  If R goes away while E is still pending,
+// then it is important to "revoke" E so that it does not try use R after R has
+// been destroyed.  nsRevocableEventPtr makes it easy for R to manage such
+// situations:
+//
+//   class R;
+//
+//   class E : public mozilla::Runnable {
+//   public:
+//     void Revoke() {
+//       mResource = nullptr;
+//     }
+//   private:
+//     R *mResource;
+//   };
+//
+//   class R {
+//   public:
+//     void EventHandled() {
+//       mEvent.Forget();
+//     }
+//   private:
+//     nsRevocableEventPtr<E> mEvent;
+//   };
+//
+//   void R::PostEvent() {
+//     // Make sure any pending event is revoked.
+//     mEvent->Revoke();
+//
+//     nsCOMPtr<nsIRunnable> event = new E();
+//     if (NS_SUCCEEDED(NS_DispatchToCurrentThread(event))) {
+//       // Keep pointer to event so we can revoke it.
+//       mEvent = event;
+//     }
+//   }
+//
+//   NS_IMETHODIMP E::Run() {
+//     if (!mResource)
+//       return NS_OK;
+//     ...
+//     mResource->EventHandled();
+//     return NS_OK;
+//   }
+//
+template<class T>
+class nsRevocableEventPtr
+{
+public:
+  nsRevocableEventPtr() : mEvent(nullptr) {}
+  ~nsRevocableEventPtr() { Revoke(); }
+
+  const nsRevocableEventPtr& operator=(T* aEvent)
+  {
+    if (mEvent != aEvent) {
+      Revoke();
+      mEvent = aEvent;
+    }
+    return *this;
+  }
+
+  const nsRevocableEventPtr& operator=(already_AddRefed<T> aEvent)
+  {
+    RefPtr<T> event = aEvent;
+    if (mEvent != event) {
+      Revoke();
+      mEvent = event.forget();
+    }
+    return *this;
+  }
+
+  void Revoke()
+  {
+    if (mEvent) {
+      mEvent->Revoke();
+      mEvent = nullptr;
+    }
+  }
+
+  void Forget() { mEvent = nullptr; }
+  bool IsPending() { return mEvent != nullptr; }
+  T* get() { return mEvent; }
+
+private:
+  // Not implemented
+  nsRevocableEventPtr(const nsRevocableEventPtr&);
+  nsRevocableEventPtr& operator=(const nsRevocableEventPtr&);
+
+  RefPtr<T> mEvent;
+};
+
+/**
+ * A simple helper to suffix thread pool name
+ * with incremental numbers.
+ */
+class nsThreadPoolNaming
+{
+public:
+  nsThreadPoolNaming() : mCounter(0) {}
+
+  /**
+   * Creates and sets next thread name as "<aPoolName> #<n>"
+   * on the specified thread.  If no thread is specified (aThread
+   * is null) then the name is synchronously set on the current thread.
+   */
+  void SetThreadPoolName(const nsACString& aPoolName,
+                         nsIThread* aThread = nullptr);
+
+private:
+  mozilla::Atomic<uint32_t> mCounter;
+
+  nsThreadPoolNaming(const nsThreadPoolNaming&) = delete;
+  void operator=(const nsThreadPoolNaming&) = delete;
+};
+
+/**
+ * Thread priority in most operating systems affect scheduling, not IO.  This
+ * helper is used to set the current thread to low IO priority for the lifetime
+ * of the created object.  You can only use this low priority IO setting within
+ * the context of the current thread.
+ */
+class MOZ_STACK_CLASS nsAutoLowPriorityIO
+{
+public:
+  nsAutoLowPriorityIO();
+  ~nsAutoLowPriorityIO();
+
+private:
+  bool lowIOPrioritySet;
+#if defined(XP_MACOSX)
+  int oldPriority;
+#endif
+};
+
+void
+NS_SetMainThread();
+
+#endif  // nsThreadUtils_h__
diff --git a/xpcom/glue/nsVersionComparator.cpp b/xpcom/glue/nsVersionComparator.cpp
new file mode 100644
index 000000000..6be32b974
--- /dev/null
+++ b/xpcom/glue/nsVersionComparator.cpp
@@ -0,0 +1,379 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsVersionComparator.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#if defined(XP_WIN) && !defined(UPDATER_NO_STRING_GLUE_STL)
+#include <wchar.h>
+#include "nsStringGlue.h"
+#endif
+
+struct VersionPart
+{
+  int32_t     numA;
+
+  const char* strB;    // NOT null-terminated, can be a null pointer
+  uint32_t    strBlen;
+
+  int32_t     numC;
+
+  char*       extraD;  // null-terminated
+};
+
+#ifdef XP_WIN
+struct VersionPartW
+{
+  int32_t     numA;
+
+  wchar_t*    strB;    // NOT null-terminated, can be a null pointer
+  uint32_t    strBlen;
+
+  int32_t     numC;
+
+  wchar_t*    extraD;  // null-terminated
+
+};
+#endif
+
+/**
+ * Parse a version part into a number and "extra text".
+ *
+ * @returns A pointer to the next versionpart, or null if none.
+ */
+static char*
+ParseVP(char* aPart, VersionPart& aResult)
+{
+  char* dot;
+
+  aResult.numA = 0;
+  aResult.strB = nullptr;
+  aResult.strBlen = 0;
+  aResult.numC = 0;
+  aResult.extraD = nullptr;
+
+  if (!aPart) {
+    return aPart;
+  }
+
+  dot = strchr(aPart, '.');
+  if (dot) {
+    *dot = '\0';
+  }
+
+  if (aPart[0] == '*' && aPart[1] == '\0') {
+    aResult.numA = INT32_MAX;
+    aResult.strB = "";
+  } else {
+    aResult.numA = strtol(aPart, const_cast<char**>(&aResult.strB), 10);
+  }
+
+  if (!*aResult.strB) {
+    aResult.strB = nullptr;
+    aResult.strBlen = 0;
+  } else {
+    if (aResult.strB[0] == '+') {
+      static const char kPre[] = "pre";
+
+      ++aResult.numA;
+      aResult.strB = kPre;
+      aResult.strBlen = sizeof(kPre) - 1;
+    } else {
+      const char* numstart = strpbrk(aResult.strB, "0123456789+-");
+      if (!numstart) {
+        aResult.strBlen = strlen(aResult.strB);
+      } else {
+        aResult.strBlen = numstart - aResult.strB;
+
+        aResult.numC = strtol(numstart, &aResult.extraD, 10);
+        if (!*aResult.extraD) {
+          aResult.extraD = nullptr;
+        }
+      }
+    }
+  }
+
+  if (dot) {
+    ++dot;
+
+    if (!*dot) {
+      dot = nullptr;
+    }
+  }
+
+  return dot;
+}
+
+
+/**
+ * Parse a version part into a number and "extra text".
+ *
+ * @returns A pointer to the next versionpart, or null if none.
+ */
+#ifdef XP_WIN
+static wchar_t*
+ParseVP(wchar_t* aPart, VersionPartW& aResult)
+{
+
+  wchar_t* dot;
+
+  aResult.numA = 0;
+  aResult.strB = nullptr;
+  aResult.strBlen = 0;
+  aResult.numC = 0;
+  aResult.extraD = nullptr;
+
+  if (!aPart) {
+    return aPart;
+  }
+
+  dot = wcschr(aPart, '.');
+  if (dot) {
+    *dot = '\0';
+  }
+
+  if (aPart[0] == '*' && aPart[1] == '\0') {
+    aResult.numA = INT32_MAX;
+    aResult.strB = L"";
+  } else {
+    aResult.numA = wcstol(aPart, const_cast<wchar_t**>(&aResult.strB), 10);
+  }
+
+  if (!*aResult.strB) {
+    aResult.strB = nullptr;
+    aResult.strBlen = 0;
+  } else {
+    if (aResult.strB[0] == '+') {
+      static wchar_t kPre[] = L"pre";
+
+      ++aResult.numA;
+      aResult.strB = kPre;
+      aResult.strBlen = sizeof(kPre) - 1;
+    } else {
+      const wchar_t* numstart = wcspbrk(aResult.strB, L"0123456789+-");
+      if (!numstart) {
+        aResult.strBlen = wcslen(aResult.strB);
+      } else {
+        aResult.strBlen = numstart - aResult.strB;
+
+        aResult.numC = wcstol(numstart, &aResult.extraD, 10);
+        if (!*aResult.extraD) {
+          aResult.extraD = nullptr;
+        }
+      }
+    }
+  }
+
+  if (dot) {
+    ++dot;
+
+    if (!*dot) {
+      dot = nullptr;
+    }
+  }
+
+  return dot;
+}
+#endif
+
+// compare two null-terminated strings, which may be null pointers
+static int32_t
+ns_strcmp(const char* aStr1, const char* aStr2)
+{
+  // any string is *before* no string
+  if (!aStr1) {
+    return aStr2 != 0;
+  }
+
+  if (!aStr2) {
+    return -1;
+  }
+
+  return strcmp(aStr1, aStr2);
+}
+
+// compare two length-specified string, which may be null pointers
+static int32_t
+ns_strnncmp(const char* aStr1, uint32_t aLen1,
+            const char* aStr2, uint32_t aLen2)
+{
+  // any string is *before* no string
+  if (!aStr1) {
+    return aStr2 != 0;
+  }
+
+  if (!aStr2) {
+    return -1;
+  }
+
+  for (; aLen1 && aLen2; --aLen1, --aLen2, ++aStr1, ++aStr2) {
+    if (*aStr1 < *aStr2) {
+      return -1;
+    }
+
+    if (*aStr1 > *aStr2) {
+      return 1;
+    }
+  }
+
+  if (aLen1 == 0) {
+    return aLen2 == 0 ? 0 : -1;
+  }
+
+  return 1;
+}
+
+// compare two int32_t
+static int32_t
+ns_cmp(int32_t aNum1, int32_t aNum2)
+{
+  if (aNum1 < aNum2) {
+    return -1;
+  }
+
+  return aNum1 != aNum2;
+}
+
+/**
+ * Compares two VersionParts
+ */
+static int32_t
+CompareVP(VersionPart& aVer1, VersionPart& aVer2)
+{
+  int32_t r = ns_cmp(aVer1.numA, aVer2.numA);
+  if (r) {
+    return r;
+  }
+
+  r = ns_strnncmp(aVer1.strB, aVer1.strBlen, aVer2.strB, aVer2.strBlen);
+  if (r) {
+    return r;
+  }
+
+  r = ns_cmp(aVer1.numC, aVer2.numC);
+  if (r) {
+    return r;
+  }
+
+  return ns_strcmp(aVer1.extraD, aVer2.extraD);
+}
+
+/**
+ * Compares two VersionParts
+ */
+#ifdef XP_WIN
+static int32_t
+CompareVP(VersionPartW& aVer1, VersionPartW& aVer2)
+{
+  int32_t r = ns_cmp(aVer1.numA, aVer2.numA);
+  if (r) {
+    return r;
+  }
+
+  r = wcsncmp(aVer1.strB, aVer2.strB, XPCOM_MIN(aVer1.strBlen, aVer2.strBlen));
+  if (r) {
+    return r;
+  }
+
+  r = ns_cmp(aVer1.numC, aVer2.numC);
+  if (r) {
+    return r;
+  }
+
+  if (!aVer1.extraD) {
+    return aVer2.extraD != 0;
+  }
+
+  if (!aVer2.extraD) {
+    return -1;
+  }
+
+  return wcscmp(aVer1.extraD, aVer2.extraD);
+}
+#endif
+
+namespace mozilla {
+
+#ifdef XP_WIN
+int32_t
+CompareVersions(const char16_t* aStrA, const char16_t* aStrB)
+{
+  wchar_t* A2 = wcsdup(char16ptr_t(aStrA));
+  if (!A2) {
+    return 1;
+  }
+
+  wchar_t* B2 = wcsdup(char16ptr_t(aStrB));
+  if (!B2) {
+    free(A2);
+    return 1;
+  }
+
+  int32_t result;
+  wchar_t* a = A2;
+  wchar_t* b = B2;
+
+  do {
+    VersionPartW va, vb;
+
+    a = ParseVP(a, va);
+    b = ParseVP(b, vb);
+
+    result = CompareVP(va, vb);
+    if (result) {
+      break;
+    }
+
+  } while (a || b);
+
+  free(A2);
+  free(B2);
+
+  return result;
+}
+#endif
+
+int32_t
+CompareVersions(const char* aStrA, const char* aStrB)
+{
+  char* A2 = strdup(aStrA);
+  if (!A2) {
+    return 1;
+  }
+
+  char* B2 = strdup(aStrB);
+  if (!B2) {
+    free(A2);
+    return 1;
+  }
+
+  int32_t result;
+  char* a = A2;
+  char* b = B2;
+
+  do {
+    VersionPart va, vb;
+
+    a = ParseVP(a, va);
+    b = ParseVP(b, vb);
+
+    result = CompareVP(va, vb);
+    if (result) {
+      break;
+    }
+
+  } while (a || b);
+
+  free(A2);
+  free(B2);
+
+  return result;
+}
+
+} // namespace mozilla
+
diff --git a/xpcom/glue/nsVersionComparator.h b/xpcom/glue/nsVersionComparator.h
new file mode 100644
index 000000000..0dbf8532b
--- /dev/null
+++ b/xpcom/glue/nsVersionComparator.h
@@ -0,0 +1,174 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsVersionComparator_h__
+#define nsVersionComparator_h__
+
+#include "nscore.h"
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#if defined(XP_WIN) && !defined(UPDATER_NO_STRING_GLUE_STL)
+#include <wchar.h>
+#include "nsStringGlue.h"
+#endif
+
+/**
+ * In order to compare version numbers in Mozilla, you need to use the
+ * mozilla::Version class.  You can construct an object of this type by passing
+ * in a string version number to the constructor.  Objects of this type can be
+ * compared using the standard comparison operators.
+ *
+ * For example, let's say that you want to make sure that a given version
+ * number is not older than 15.a2.  Here's how you would write a function to
+ * do that.
+ *
+ * bool IsVersionValid(const char* version) {
+ *   return mozilla::Version("15.a2") <= mozilla::Version(version);
+ * }
+ *
+ * Or, since Version's constructor is implicit, you can simplify this code:
+ *
+ * bool IsVersionValid(const char* version) {
+ *   return mozilla::Version("15.a2") <= version;
+ * }
+ *
+ * On Windows, if your version strings are wide characters, you should use the
+ * mozilla::VersionW variant instead.  The semantics of that class is the same
+ * as Version.
+ */
+
+namespace mozilla {
+
+int32_t CompareVersions(const char* aStrA, const char* aStrB);
+
+#ifdef XP_WIN
+int32_t CompareVersions(const char16_t* aStrA, const char16_t* aStrB);
+#endif
+
+struct Version
+{
+  explicit Version(const char* aVersionString)
+  {
+    versionContent = strdup(aVersionString);
+  }
+
+  const char* ReadContent() const
+  {
+    return versionContent;
+  }
+
+  ~Version()
+  {
+    free(versionContent);
+  }
+
+  bool operator<(const Version& aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs.ReadContent()) == -1;
+  }
+  bool operator<=(const Version& aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs.ReadContent()) < 1;
+  }
+  bool operator>(const Version& aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs.ReadContent()) == 1;
+  }
+  bool operator>=(const Version& aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs.ReadContent()) > -1;
+  }
+  bool operator==(const Version& aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs.ReadContent()) == 0;
+  }
+  bool operator!=(const Version& aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs.ReadContent()) != 0;
+  }
+  bool operator<(const char* aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs) == -1;
+  }
+  bool operator<=(const char* aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs) < 1;
+  }
+  bool operator>(const char* aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs) == 1;
+  }
+  bool operator>=(const char* aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs) > -1;
+  }
+  bool operator==(const char* aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs) == 0;
+  }
+  bool operator!=(const char* aRhs) const
+  {
+    return CompareVersions(versionContent, aRhs) != 0;
+  }
+
+private:
+  char* versionContent;
+};
+
+#ifdef XP_WIN
+struct VersionW
+{
+  VersionW(const char16_t* aVersionStringW)
+  {
+    versionContentW =
+      reinterpret_cast<char16_t*>(wcsdup(char16ptr_t(aVersionStringW)));
+  }
+
+  const char16_t* ReadContentW() const
+  {
+    return versionContentW;
+  }
+
+  ~VersionW()
+  {
+    free(versionContentW);
+  }
+
+  bool operator<(const VersionW& aRhs) const
+  {
+    return CompareVersions(versionContentW, aRhs.ReadContentW()) == -1;
+  }
+  bool operator<=(const VersionW& aRhs) const
+  {
+    return CompareVersions(versionContentW, aRhs.ReadContentW()) < 1;
+  }
+  bool operator>(const VersionW& aRhs) const
+  {
+    return CompareVersions(versionContentW, aRhs.ReadContentW()) == 1;
+  }
+  bool operator>=(const VersionW& aRhs) const
+  {
+    return CompareVersions(versionContentW, aRhs.ReadContentW()) > -1;
+  }
+  bool operator==(const VersionW& aRhs) const
+  {
+    return CompareVersions(versionContentW, aRhs.ReadContentW()) == 0;
+  }
+  bool operator!=(const VersionW& aRhs) const
+  {
+    return CompareVersions(versionContentW, aRhs.ReadContentW()) != 0;
+  }
+
+private:
+  char16_t* versionContentW;
+};
+#endif
+
+} // namespace mozilla
+
+#endif // nsVersionComparator_h__
+
diff --git a/xpcom/glue/nsWeakReference.cpp b/xpcom/glue/nsWeakReference.cpp
new file mode 100644
index 000000000..57f372641
--- /dev/null
+++ b/xpcom/glue/nsWeakReference.cpp
@@ -0,0 +1,164 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// nsWeakReference.cpp
+
+#include "mozilla/Attributes.h"
+
+#include "nsWeakReference.h"
+#include "nsCOMPtr.h"
+#include "nsDebug.h"
+
+#ifdef MOZ_THREAD_SAFETY_OWNERSHIP_CHECKS_SUPPORTED
+
+#define MOZ_WEAKREF_DECL_OWNINGTHREAD nsAutoOwningThread _mWeakRefOwningThread;
+#define MOZ_WEAKREF_ASSERT_OWNINGTHREAD \
+  NS_CheckThreadSafe(_mWeakRefOwningThread.GetThread(), "nsWeakReference not thread-safe")
+#define MOZ_WEAKREF_ASSERT_OWNINGTHREAD_DELEGATED(that) \
+  NS_CheckThreadSafe((that)->_mWeakRefOwningThread.GetThread(), "nsWeakReference not thread-safe")
+
+#else
+
+#define MOZ_WEAKREF_DECL_OWNINGTHREAD
+#define MOZ_WEAKREF_ASSERT_OWNINGTHREAD do { } while (false)
+#define MOZ_WEAKREF_ASSERT_OWNINGTHREAD_DELEGATED(that) do { } while (false)
+
+#endif
+
+class nsWeakReference final : public nsIWeakReference
+{
+public:
+  // nsISupports...
+  NS_DECL_ISUPPORTS
+
+  // nsIWeakReference...
+  NS_DECL_NSIWEAKREFERENCE
+  virtual size_t SizeOfOnlyThis(mozilla::MallocSizeOf aMallocSizeOf) const override;
+
+private:
+  MOZ_WEAKREF_DECL_OWNINGTHREAD
+
+  friend class nsSupportsWeakReference;
+
+  explicit nsWeakReference(nsSupportsWeakReference* aReferent)
+    : mReferent(aReferent)
+    // ...I can only be constructed by an |nsSupportsWeakReference|
+  {
+  }
+
+  ~nsWeakReference()
+  // ...I will only be destroyed by calling |delete| myself.
+  {
+    MOZ_WEAKREF_ASSERT_OWNINGTHREAD;
+    if (mReferent) {
+      mReferent->NoticeProxyDestruction();
+    }
+  }
+
+  void
+  NoticeReferentDestruction()
+  // ...called (only) by an |nsSupportsWeakReference| from _its_ dtor.
+  {
+    MOZ_WEAKREF_ASSERT_OWNINGTHREAD;
+    mReferent = nullptr;
+  }
+
+  nsSupportsWeakReference* MOZ_NON_OWNING_REF mReferent;
+};
+
+nsresult
+nsQueryReferent::operator()(const nsIID& aIID, void** aAnswer) const
+{
+  nsresult status;
+  if (mWeakPtr) {
+    if (NS_FAILED(status = mWeakPtr->QueryReferent(aIID, aAnswer))) {
+      *aAnswer = 0;
+    }
+  } else {
+    status = NS_ERROR_NULL_POINTER;
+  }
+
+  if (mErrorPtr) {
+    *mErrorPtr = status;
+  }
+  return status;
+}
+
+nsIWeakReference*  // or else |already_AddRefed<nsIWeakReference>|
+NS_GetWeakReference(nsISupports* aInstancePtr, nsresult* aErrorPtr)
+{
+  nsresult status;
+
+  nsIWeakReference* result = nullptr;
+
+  if (aInstancePtr) {
+    nsCOMPtr<nsISupportsWeakReference> factoryPtr =
+      do_QueryInterface(aInstancePtr, &status);
+    if (factoryPtr) {
+      status = factoryPtr->GetWeakReference(&result);
+    }
+    // else, |status| has already been set by |do_QueryInterface|
+  } else {
+    status = NS_ERROR_NULL_POINTER;
+  }
+
+  if (aErrorPtr) {
+    *aErrorPtr = status;
+  }
+  return result;
+}
+
+nsresult
+nsSupportsWeakReference::GetWeakReference(nsIWeakReference** aInstancePtr)
+{
+  if (!aInstancePtr) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  if (!mProxy) {
+    mProxy = new nsWeakReference(this);
+  } else {
+    MOZ_WEAKREF_ASSERT_OWNINGTHREAD_DELEGATED(mProxy);
+  }
+  *aInstancePtr = mProxy;
+
+  nsresult status;
+  if (!*aInstancePtr) {
+    status = NS_ERROR_OUT_OF_MEMORY;
+  } else {
+    NS_ADDREF(*aInstancePtr);
+    status = NS_OK;
+  }
+
+  return status;
+}
+
+NS_IMPL_ISUPPORTS(nsWeakReference, nsIWeakReference)
+
+NS_IMETHODIMP
+nsWeakReference::QueryReferent(const nsIID& aIID, void** aInstancePtr)
+{
+  MOZ_WEAKREF_ASSERT_OWNINGTHREAD;
+
+  return mReferent ? mReferent->QueryInterface(aIID, aInstancePtr) :
+                     NS_ERROR_NULL_POINTER;
+}
+
+size_t
+nsWeakReference::SizeOfOnlyThis(mozilla::MallocSizeOf aMallocSizeOf) const
+{
+  return aMallocSizeOf(this);
+}
+
+void
+nsSupportsWeakReference::ClearWeakReferences()
+{
+  if (mProxy) {
+    mProxy->NoticeReferentDestruction();
+    mProxy = nullptr;
+  }
+}
+
diff --git a/xpcom/glue/nsWeakReference.h b/xpcom/glue/nsWeakReference.h
new file mode 100644
index 000000000..fc875ba96
--- /dev/null
+++ b/xpcom/glue/nsWeakReference.h
@@ -0,0 +1,49 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsWeakReference_h__
+#define nsWeakReference_h__
+
+// nsWeakReference.h
+
+// See mfbt/WeakPtr.h for a more typesafe C++ implementation of weak references
+
+#include "nsIWeakReferenceUtils.h"
+
+class nsWeakReference;
+
+class nsSupportsWeakReference : public nsISupportsWeakReference
+{
+public:
+  nsSupportsWeakReference() : mProxy(0) {}
+
+  NS_DECL_NSISUPPORTSWEAKREFERENCE
+
+protected:
+  inline ~nsSupportsWeakReference();
+
+private:
+  friend class nsWeakReference;
+
+  // Called (only) by an |nsWeakReference| from _its_ dtor.
+  // The thread safety check is made by the caller.
+  void NoticeProxyDestruction() { mProxy = nullptr; }
+
+  nsWeakReference* MOZ_NON_OWNING_REF mProxy;
+
+protected:
+
+  void ClearWeakReferences();
+  bool HasWeakReferences() const { return !!mProxy; }
+};
+
+inline
+nsSupportsWeakReference::~nsSupportsWeakReference()
+{
+  ClearWeakReferences();
+}
+
+#endif
diff --git a/xpcom/glue/nsXPTCUtils.h b/xpcom/glue/nsXPTCUtils.h
new file mode 100644
index 000000000..8922aca16
--- /dev/null
+++ b/xpcom/glue/nsXPTCUtils.h
@@ -0,0 +1,45 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsXPTCUtils_h__
+#define nsXPTCUtils_h__
+
+#include "xptcall.h"
+#include "mozilla/MemoryReporting.h"
+
+/**
+ * A helper class that initializes an xptcall helper at construction
+ * and releases it at destruction.
+ */
+class nsAutoXPTCStub : protected nsIXPTCProxy
+{
+public:
+  nsISomeInterface* mXPTCStub;
+
+protected:
+  nsAutoXPTCStub() : mXPTCStub(nullptr) {}
+
+  nsresult
+  InitStub(const nsIID& aIID)
+  {
+    return NS_GetXPTCallStub(aIID, this, &mXPTCStub);
+  }
+
+  ~nsAutoXPTCStub()
+  {
+    if (mXPTCStub) {
+      NS_DestroyXPTCallStub(mXPTCStub);
+    }
+  }
+
+  size_t
+  SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return mXPTCStub ? NS_SizeOfIncludingThisXPTCallStub(mXPTCStub, aMallocSizeOf) : 0;
+  }
+};
+
+#endif // nsXPTCUtils_h__
diff --git a/xpcom/glue/objs.mozbuild b/xpcom/glue/objs.mozbuild
new file mode 100644
index 000000000..8161e1ebc
--- /dev/null
+++ b/xpcom/glue/objs.mozbuild
@@ -0,0 +1,48 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+xpcom_glue_src_lcppsrcs = [
+    'AppData.cpp',
+    'FileUtils.cpp',
+    'nsArrayEnumerator.cpp',
+    'nsArrayUtils.cpp',
+    'nsCategoryCache.cpp',
+    'nsClassInfoImpl.cpp',
+    'nsCOMArray.cpp',
+    'nsComponentManagerUtils.cpp',
+    'nsCOMPtr.cpp',
+    'nsCRTGlue.cpp',
+    'nsCycleCollectionParticipant.cpp',
+    'nsDeque.cpp',
+    'nsEnumeratorUtils.cpp',
+    'nsID.cpp',
+    'nsIInterfaceRequestorUtils.cpp',
+    'nsINIParser.cpp',
+    'nsISupportsImpl.cpp',
+    'nsMemory.cpp',
+    'nsQuickSort.cpp',
+    'nsTArray.cpp',
+    'nsThreadUtils.cpp',
+    'nsTObserverArray.cpp',
+    'nsVersionComparator.cpp',
+    'nsWeakReference.cpp',
+    'PLDHashTable.cpp',
+]
+
+xpcom_glue_src_cppsrcs = [
+    '/xpcom/glue/%s' % s for s in xpcom_glue_src_lcppsrcs
+]
+
+xpcom_gluens_src_lcppsrcs = [
+    'BlockingResourceBase.cpp',
+    'GenericFactory.cpp',
+    'nsProxyRelease.cpp',
+    'nsTextFormatter.cpp',
+]
+
+xpcom_gluens_src_cppsrcs = [
+    '/xpcom/glue/%s' % s for s in xpcom_gluens_src_lcppsrcs
+]
diff --git a/xpcom/glue/standalone/moz.build b/xpcom/glue/standalone/moz.build
new file mode 100644
index 000000000..fd91fa0bb
--- /dev/null
+++ b/xpcom/glue/standalone/moz.build
@@ -0,0 +1,58 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# On win we build two glue libs - glue linked to crt dlls here and in staticruntime we build
+# a statically linked glue lib.
+if CONFIG['OS_ARCH'] == 'WINNT':
+    DIRS += ['staticruntime']
+
+include('../objs.mozbuild')
+
+SOURCES += xpcom_glue_src_cppsrcs
+
+SOURCES += [
+    '../nsStringAPI.cpp',
+    'nsXPCOMGlue.cpp',
+]
+
+Library('xpcomglue')
+
+EXPORTS += [
+    'nsXPCOMGlue.h',
+]
+
+SDK_LIBRARY = True
+
+FORCE_STATIC_LIB = True
+
+if CONFIG['_MSC_VER']:
+    DEFINES['_USE_ANSI_CPP'] = True
+    # Don't include directives about which CRT to use
+    CFLAGS += ['-Zl']
+    CXXFLAGS += ['-Zl']
+
+DEFINES['XPCOM_GLUE'] = True
+
+LOCAL_INCLUDES += [
+    '../../build',
+    '../../threads',
+]
+
+# Don't use STL wrappers here (i.e. wrapped <new>); they require mozalloc
+DISABLE_STL_WRAPPING = True
+
+# Include fallible for third party code using the xpcom glue
+USE_LIBS += [
+    'fallible',
+]
+
+# Force to build a static library only
+NO_EXPAND_LIBS = True
+
+DIST_INSTALL = True
+
+if CONFIG['MOZ_WIDGET_TOOLKIT'] in ('gtk2', 'gtk3'):
+    CXXFLAGS += CONFIG['GLIB_CFLAGS']
diff --git a/xpcom/glue/standalone/nsXPCOMGlue.cpp b/xpcom/glue/standalone/nsXPCOMGlue.cpp
new file mode 100644
index 000000000..b657d7050
--- /dev/null
+++ b/xpcom/glue/standalone/nsXPCOMGlue.cpp
@@ -0,0 +1,927 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsXPCOMGlue.h"
+
+#include "nspr.h"
+#include "nsDebug.h"
+#include "nsIServiceManager.h"
+#include "nsXPCOMPrivate.h"
+#include "nsCOMPtr.h"
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "mozilla/FileUtils.h"
+#include "mozilla/Sprintf.h"
+
+using namespace mozilla;
+
+#define XPCOM_DEPENDENT_LIBS_LIST "dependentlibs.list"
+
+static XPCOMFunctions xpcomFunctions;
+static bool do_preload = false;
+
+#if defined(XP_WIN)
+#define READ_TEXTMODE L"rt"
+#else
+#define READ_TEXTMODE "r"
+#endif
+
+#if defined(XP_WIN)
+#include <windows.h>
+#include <mbstring.h>
+
+typedef HINSTANCE LibHandleType;
+
+static LibHandleType
+GetLibHandle(pathstr_t aDependentLib)
+{
+  LibHandleType libHandle =
+    LoadLibraryExW(aDependentLib, nullptr, LOAD_WITH_ALTERED_SEARCH_PATH);
+
+#ifdef DEBUG
+  if (!libHandle) {
+    DWORD err = GetLastError();
+    LPWSTR lpMsgBuf;
+    FormatMessageW(
+      FORMAT_MESSAGE_ALLOCATE_BUFFER |
+      FORMAT_MESSAGE_FROM_SYSTEM |
+      FORMAT_MESSAGE_IGNORE_INSERTS,
+      nullptr,
+      err,
+      MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+      (LPWSTR)&lpMsgBuf,
+      0,
+      nullptr
+    );
+    wprintf(L"Error loading %ls: %s\n", aDependentLib, lpMsgBuf);
+    LocalFree(lpMsgBuf);
+  }
+#endif
+
+  return libHandle;
+}
+
+static NSFuncPtr
+GetSymbol(LibHandleType aLibHandle, const char* aSymbol)
+{
+  return (NSFuncPtr)GetProcAddress(aLibHandle, aSymbol);
+}
+
+static void
+CloseLibHandle(LibHandleType aLibHandle)
+{
+  FreeLibrary(aLibHandle);
+}
+
+#else
+#include <dlfcn.h>
+
+#if defined(MOZ_LINKER) && !defined(ANDROID)
+extern "C" {
+NS_HIDDEN __typeof(dlopen) __wrap_dlopen;
+NS_HIDDEN __typeof(dlsym) __wrap_dlsym;
+NS_HIDDEN __typeof(dlclose) __wrap_dlclose;
+}
+
+#define dlopen __wrap_dlopen
+#define dlsym __wrap_dlsym
+#define dlclose __wrap_dlclose
+#endif
+
+typedef void* LibHandleType;
+
+static LibHandleType
+GetLibHandle(pathstr_t aDependentLib)
+{
+  LibHandleType libHandle = dlopen(aDependentLib,
+                                   RTLD_GLOBAL | RTLD_LAZY
+#ifdef XP_MACOSX
+                                   | RTLD_FIRST
+#endif
+                                   );
+  if (!libHandle) {
+    fprintf(stderr, "XPCOMGlueLoad error for file %s:\n%s\n", aDependentLib,
+            dlerror());
+  }
+  return libHandle;
+}
+
+static NSFuncPtr
+GetSymbol(LibHandleType aLibHandle, const char* aSymbol)
+{
+  return (NSFuncPtr)dlsym(aLibHandle, aSymbol);
+}
+
+static void
+CloseLibHandle(LibHandleType aLibHandle)
+{
+  dlclose(aLibHandle);
+}
+#endif
+
+struct DependentLib
+{
+  LibHandleType libHandle;
+  DependentLib* next;
+};
+
+static DependentLib* sTop;
+
+static void
+AppendDependentLib(LibHandleType aLibHandle)
+{
+  DependentLib* d = new DependentLib;
+  if (!d) {
+    return;
+  }
+
+  d->next = sTop;
+  d->libHandle = aLibHandle;
+
+  sTop = d;
+}
+
+static bool
+ReadDependentCB(pathstr_t aDependentLib, bool aDoPreload)
+{
+  if (aDoPreload) {
+    ReadAheadLib(aDependentLib);
+  }
+  LibHandleType libHandle = GetLibHandle(aDependentLib);
+  if (libHandle) {
+    AppendDependentLib(libHandle);
+  }
+
+  return libHandle;
+}
+
+#ifdef XP_WIN
+static bool
+ReadDependentCB(const char* aDependentLib, bool do_preload)
+{
+  wchar_t wideDependentLib[MAX_PATH];
+  MultiByteToWideChar(CP_UTF8, 0, aDependentLib, -1, wideDependentLib, MAX_PATH);
+  return ReadDependentCB(wideDependentLib, do_preload);
+}
+
+inline FILE*
+TS_tfopen(const char* path, const wchar_t* mode)
+{
+  wchar_t wPath[MAX_PATH];
+  MultiByteToWideChar(CP_UTF8, 0, path, -1, wPath, MAX_PATH);
+  return _wfopen(wPath, mode);
+}
+#else
+inline FILE*
+TS_tfopen(const char* aPath, const char* aMode)
+{
+  return fopen(aPath, aMode);
+}
+#endif
+
+/* RAII wrapper for FILE descriptors */
+struct ScopedCloseFileTraits
+{
+  typedef FILE* type;
+  static type empty() { return nullptr; }
+  static void release(type aFile)
+  {
+    if (aFile) {
+      fclose(aFile);
+    }
+  }
+};
+typedef Scoped<ScopedCloseFileTraits> ScopedCloseFile;
+
+static void
+XPCOMGlueUnload()
+{
+  while (sTop) {
+    CloseLibHandle(sTop->libHandle);
+
+    DependentLib* temp = sTop;
+    sTop = sTop->next;
+
+    delete temp;
+  }
+}
+
+#if defined(XP_WIN)
+// like strpbrk but finds the *last* char, not the first
+static const char*
+ns_strrpbrk(const char* string, const char* strCharSet)
+{
+  const char* found = nullptr;
+  for (; *string; ++string) {
+    for (const char* search = strCharSet; *search; ++search) {
+      if (*search == *string) {
+        found = string;
+        // Since we're looking for the last char, we save "found"
+        // until we're at the end of the string.
+      }
+    }
+  }
+
+  return found;
+}
+#endif
+
+static GetFrozenFunctionsFunc
+XPCOMGlueLoad(const char* aXPCOMFile)
+{
+  char xpcomDir[MAXPATHLEN];
+#ifdef XP_WIN
+  const char* lastSlash = ns_strrpbrk(aXPCOMFile, "/\\");
+#elif XP_MACOSX
+  // On OSX, the dependentlibs.list file lives under Contents/Resources.
+  // However, the actual libraries listed in dependentlibs.list live under
+  // Contents/MacOS. We want to read the list from Contents/Resources, then
+  // load the libraries from Contents/MacOS.
+  const char *tempSlash = strrchr(aXPCOMFile, '/');
+  size_t tempLen = size_t(tempSlash - aXPCOMFile);
+  if (tempLen > MAXPATHLEN) {
+    return nullptr;
+  }
+  char tempBuffer[MAXPATHLEN];
+  memcpy(tempBuffer, aXPCOMFile, tempLen);
+  tempBuffer[tempLen] = '\0';
+  const char *slash = strrchr(tempBuffer, '/');
+  tempLen = size_t(slash - tempBuffer);
+  const char *lastSlash = aXPCOMFile + tempLen;
+#else
+  const char* lastSlash = strrchr(aXPCOMFile, '/');
+#endif
+  char* cursor;
+  if (lastSlash) {
+    size_t len = size_t(lastSlash - aXPCOMFile);
+
+    if (len > MAXPATHLEN - sizeof(XPCOM_FILE_PATH_SEPARATOR
+#ifdef XP_MACOSX
+                                  "Resources"
+                                  XPCOM_FILE_PATH_SEPARATOR
+#endif
+                                  XPCOM_DEPENDENT_LIBS_LIST)) {
+      return nullptr;
+    }
+    memcpy(xpcomDir, aXPCOMFile, len);
+    strcpy(xpcomDir + len, XPCOM_FILE_PATH_SEPARATOR
+#ifdef XP_MACOSX
+                           "Resources"
+                           XPCOM_FILE_PATH_SEPARATOR
+#endif
+                           XPCOM_DEPENDENT_LIBS_LIST);
+    cursor = xpcomDir + len + 1;
+  } else {
+    strcpy(xpcomDir, XPCOM_DEPENDENT_LIBS_LIST);
+    cursor = xpcomDir;
+  }
+
+  if (getenv("MOZ_RUN_GTEST")) {
+    strcat(xpcomDir, ".gtest");
+  }
+
+  ScopedCloseFile flist;
+  flist = TS_tfopen(xpcomDir, READ_TEXTMODE);
+  if (!flist) {
+    return nullptr;
+  }
+
+#ifdef XP_MACOSX
+  tempLen = size_t(cursor - xpcomDir);
+  if (tempLen > MAXPATHLEN - sizeof("MacOS" XPCOM_FILE_PATH_SEPARATOR) - 1) {
+    return nullptr;
+  }
+  strcpy(cursor, "MacOS" XPCOM_FILE_PATH_SEPARATOR);
+  cursor += strlen(cursor);
+#endif
+  *cursor = '\0';
+
+  char buffer[MAXPATHLEN];
+
+  while (fgets(buffer, sizeof(buffer), flist)) {
+    int l = strlen(buffer);
+
+    // ignore empty lines and comments
+    if (l == 0 || *buffer == '#') {
+      continue;
+    }
+
+    // cut the trailing newline, if present
+    if (buffer[l - 1] == '\n') {
+      buffer[l - 1] = '\0';
+    }
+
+    if (l + size_t(cursor - xpcomDir) > MAXPATHLEN) {
+      return nullptr;
+    }
+
+    strcpy(cursor, buffer);
+    if (!ReadDependentCB(xpcomDir, do_preload)) {
+      XPCOMGlueUnload();
+      return nullptr;
+    }
+  }
+
+  GetFrozenFunctionsFunc sym =
+    (GetFrozenFunctionsFunc)GetSymbol(sTop->libHandle,
+                                      "NS_GetFrozenFunctions");
+
+  if (!sym) { // No symbol found.
+    XPCOMGlueUnload();
+    return nullptr;
+  }
+
+  return sym;
+}
+
+nsresult
+XPCOMGlueLoadXULFunctions(const nsDynamicFunctionLoad* aSymbols)
+{
+  // We don't null-check sXULLibHandle because this might work even
+  // if it is null (same as RTLD_DEFAULT)
+
+  nsresult rv = NS_OK;
+  while (aSymbols->functionName) {
+    char buffer[512];
+    SprintfLiteral(buffer, "%s", aSymbols->functionName);
+
+    *aSymbols->function = (NSFuncPtr)GetSymbol(sTop->libHandle, buffer);
+    if (!*aSymbols->function) {
+      rv = NS_ERROR_LOSS_OF_SIGNIFICANT_DATA;
+    }
+
+    ++aSymbols;
+  }
+  return rv;
+}
+
+void
+XPCOMGlueEnablePreload()
+{
+  do_preload = true;
+}
+
+#if defined(MOZ_WIDGET_GTK) && (defined(MOZ_MEMORY) || defined(__FreeBSD__) || defined(__NetBSD__))
+#define MOZ_GSLICE_INIT
+#endif
+
+#ifdef MOZ_GSLICE_INIT
+#include <glib.h>
+
+class GSliceInit {
+public:
+  GSliceInit() {
+    mHadGSlice = bool(getenv("G_SLICE"));
+    if (!mHadGSlice) {
+      // Disable the slice allocator, since jemalloc already uses similar layout
+      // algorithms, and using a sub-allocator tends to increase fragmentation.
+      // This must be done before g_thread_init() is called.
+      // glib >= 2.36 initializes g_slice as a side effect of its various static
+      // initializers, so this needs to happen before glib is loaded, which is
+      // this is hooked in XPCOMGlueStartup before libxul is loaded. This
+      // relies on the main executable not depending on glib.
+      setenv("G_SLICE", "always-malloc", 1);
+    }
+  }
+
+  ~GSliceInit() {
+#if MOZ_WIDGET_GTK == 2
+    if (sTop) {
+      auto XRE_GlibInit = (void (*)(void)) GetSymbol(sTop->libHandle,
+        "XRE_GlibInit");
+      // Initialize glib enough for G_SLICE to have an effect before it is unset.
+      // unset.
+      XRE_GlibInit();
+    }
+#endif
+    if (!mHadGSlice) {
+      unsetenv("G_SLICE");
+    }
+  }
+
+private:
+  bool mHadGSlice;
+};
+#endif
+
+nsresult
+XPCOMGlueStartup(const char* aXPCOMFile)
+{
+#ifdef MOZ_GSLICE_INIT
+  GSliceInit gSliceInit;
+#endif
+  xpcomFunctions.version = XPCOM_GLUE_VERSION;
+  xpcomFunctions.size    = sizeof(XPCOMFunctions);
+
+  if (!aXPCOMFile) {
+    aXPCOMFile = XPCOM_DLL;
+  }
+
+  GetFrozenFunctionsFunc func = XPCOMGlueLoad(aXPCOMFile);
+  if (!func) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  nsresult rv = (*func)(&xpcomFunctions, nullptr);
+  if (NS_FAILED(rv)) {
+    XPCOMGlueUnload();
+    return rv;
+  }
+
+  return NS_OK;
+}
+
+XPCOM_API(nsresult)
+NS_InitXPCOM2(nsIServiceManager** aResult,
+              nsIFile* aBinDirectory,
+              nsIDirectoryServiceProvider* aAppFileLocationProvider)
+{
+  if (!xpcomFunctions.init) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.init(aResult, aBinDirectory, aAppFileLocationProvider);
+}
+
+XPCOM_API(nsresult)
+NS_ShutdownXPCOM(nsIServiceManager* aServMgr)
+{
+  if (!xpcomFunctions.shutdown) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.shutdown(aServMgr);
+}
+
+XPCOM_API(nsresult)
+NS_GetServiceManager(nsIServiceManager** aResult)
+{
+  if (!xpcomFunctions.getServiceManager) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.getServiceManager(aResult);
+}
+
+XPCOM_API(nsresult)
+NS_GetComponentManager(nsIComponentManager** aResult)
+{
+  if (!xpcomFunctions.getComponentManager) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.getComponentManager(aResult);
+}
+
+XPCOM_API(nsresult)
+NS_GetComponentRegistrar(nsIComponentRegistrar** aResult)
+{
+  if (!xpcomFunctions.getComponentRegistrar) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.getComponentRegistrar(aResult);
+}
+
+XPCOM_API(nsresult)
+NS_GetMemoryManager(nsIMemory** aResult)
+{
+  if (!xpcomFunctions.getMemoryManager) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.getMemoryManager(aResult);
+}
+
+XPCOM_API(nsresult)
+NS_NewLocalFile(const nsAString& aPath, bool aFollowLinks, nsIFile** aResult)
+{
+  if (!xpcomFunctions.newLocalFile) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.newLocalFile(aPath, aFollowLinks, aResult);
+}
+
+XPCOM_API(nsresult)
+NS_NewNativeLocalFile(const nsACString& aPath, bool aFollowLinks,
+                      nsIFile** aResult)
+{
+  if (!xpcomFunctions.newNativeLocalFile) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.newNativeLocalFile(aPath, aFollowLinks, aResult);
+}
+
+XPCOM_API(nsresult)
+NS_GetDebug(nsIDebug2** aResult)
+{
+  if (!xpcomFunctions.getDebug) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.getDebug(aResult);
+}
+
+
+XPCOM_API(nsresult)
+NS_StringContainerInit(nsStringContainer& aStr)
+{
+  if (!xpcomFunctions.stringContainerInit) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.stringContainerInit(aStr);
+}
+
+XPCOM_API(nsresult)
+NS_StringContainerInit2(nsStringContainer& aStr, const char16_t* aData,
+                        uint32_t aDataLength, uint32_t aFlags)
+{
+  if (!xpcomFunctions.stringContainerInit2) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.stringContainerInit2(aStr, aData, aDataLength, aFlags);
+}
+
+XPCOM_API(void)
+NS_StringContainerFinish(nsStringContainer& aStr)
+{
+  if (xpcomFunctions.stringContainerFinish) {
+    xpcomFunctions.stringContainerFinish(aStr);
+  }
+}
+
+XPCOM_API(uint32_t)
+NS_StringGetData(const nsAString& aStr, const char16_t** aBuf, bool* aTerm)
+{
+  if (!xpcomFunctions.stringGetData) {
+    *aBuf = nullptr;
+    return 0;
+  }
+  return xpcomFunctions.stringGetData(aStr, aBuf, aTerm);
+}
+
+XPCOM_API(uint32_t)
+NS_StringGetMutableData(nsAString& aStr, uint32_t aLen, char16_t** aBuf)
+{
+  if (!xpcomFunctions.stringGetMutableData) {
+    *aBuf = nullptr;
+    return 0;
+  }
+  return xpcomFunctions.stringGetMutableData(aStr, aLen, aBuf);
+}
+
+XPCOM_API(char16_t*)
+NS_StringCloneData(const nsAString& aStr)
+{
+  if (!xpcomFunctions.stringCloneData) {
+    return nullptr;
+  }
+  return xpcomFunctions.stringCloneData(aStr);
+}
+
+XPCOM_API(nsresult)
+NS_StringSetData(nsAString& aStr, const char16_t* aBuf, uint32_t aCount)
+{
+  if (!xpcomFunctions.stringSetData) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return xpcomFunctions.stringSetData(aStr, aBuf, aCount);
+}
+
+XPCOM_API(nsresult)
+NS_StringSetDataRange(nsAString& aStr, uint32_t aCutStart, uint32_t aCutLength,
+                      const char16_t* aBuf, uint32_t aCount)
+{
+  if (!xpcomFunctions.stringSetDataRange) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.stringSetDataRange(aStr, aCutStart, aCutLength, aBuf,
+                                           aCount);
+}
+
+XPCOM_API(nsresult)
+NS_StringCopy(nsAString& aDest, const nsAString& aSrc)
+{
+  if (!xpcomFunctions.stringCopy) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.stringCopy(aDest, aSrc);
+}
+
+XPCOM_API(void)
+NS_StringSetIsVoid(nsAString& aStr, const bool aIsVoid)
+{
+  if (xpcomFunctions.stringSetIsVoid) {
+    xpcomFunctions.stringSetIsVoid(aStr, aIsVoid);
+  }
+}
+
+XPCOM_API(bool)
+NS_StringGetIsVoid(const nsAString& aStr)
+{
+  if (!xpcomFunctions.stringGetIsVoid) {
+    return false;
+  }
+  return xpcomFunctions.stringGetIsVoid(aStr);
+}
+
+XPCOM_API(nsresult)
+NS_CStringContainerInit(nsCStringContainer& aStr)
+{
+  if (!xpcomFunctions.cstringContainerInit) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.cstringContainerInit(aStr);
+}
+
+XPCOM_API(nsresult)
+NS_CStringContainerInit2(nsCStringContainer& aStr, const char* aData,
+                         uint32_t aDataLength, uint32_t aFlags)
+{
+  if (!xpcomFunctions.cstringContainerInit2) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.cstringContainerInit2(aStr, aData, aDataLength, aFlags);
+}
+
+XPCOM_API(void)
+NS_CStringContainerFinish(nsCStringContainer& aStr)
+{
+  if (xpcomFunctions.cstringContainerFinish) {
+    xpcomFunctions.cstringContainerFinish(aStr);
+  }
+}
+
+XPCOM_API(uint32_t)
+NS_CStringGetData(const nsACString& aStr, const char** aBuf, bool* aTerm)
+{
+  if (!xpcomFunctions.cstringGetData) {
+    *aBuf = nullptr;
+    return 0;
+  }
+  return xpcomFunctions.cstringGetData(aStr, aBuf, aTerm);
+}
+
+XPCOM_API(uint32_t)
+NS_CStringGetMutableData(nsACString& aStr, uint32_t aLen, char** aBuf)
+{
+  if (!xpcomFunctions.cstringGetMutableData) {
+    *aBuf = nullptr;
+    return 0;
+  }
+  return xpcomFunctions.cstringGetMutableData(aStr, aLen, aBuf);
+}
+
+XPCOM_API(char*)
+NS_CStringCloneData(const nsACString& aStr)
+{
+  if (!xpcomFunctions.cstringCloneData) {
+    return nullptr;
+  }
+  return xpcomFunctions.cstringCloneData(aStr);
+}
+
+XPCOM_API(nsresult)
+NS_CStringSetData(nsACString& aStr, const char* aBuf, uint32_t aCount)
+{
+  if (!xpcomFunctions.cstringSetData) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.cstringSetData(aStr, aBuf, aCount);
+}
+
+XPCOM_API(nsresult)
+NS_CStringSetDataRange(nsACString& aStr, uint32_t aCutStart,
+                       uint32_t aCutLength, const char* aBuf, uint32_t aCount)
+{
+  if (!xpcomFunctions.cstringSetDataRange) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.cstringSetDataRange(aStr, aCutStart, aCutLength, aBuf,
+                                            aCount);
+}
+
+XPCOM_API(nsresult)
+NS_CStringCopy(nsACString& aDest, const nsACString& aSrc)
+{
+  if (!xpcomFunctions.cstringCopy) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.cstringCopy(aDest, aSrc);
+}
+
+XPCOM_API(void)
+NS_CStringSetIsVoid(nsACString& aStr, const bool aIsVoid)
+{
+  if (xpcomFunctions.cstringSetIsVoid) {
+    xpcomFunctions.cstringSetIsVoid(aStr, aIsVoid);
+  }
+}
+
+XPCOM_API(bool)
+NS_CStringGetIsVoid(const nsACString& aStr)
+{
+  if (!xpcomFunctions.cstringGetIsVoid) {
+    return false;
+  }
+  return xpcomFunctions.cstringGetIsVoid(aStr);
+}
+
+XPCOM_API(nsresult)
+NS_CStringToUTF16(const nsACString& aSrc, nsCStringEncoding aSrcEncoding,
+                  nsAString& aDest)
+{
+  if (!xpcomFunctions.cstringToUTF16) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.cstringToUTF16(aSrc, aSrcEncoding, aDest);
+}
+
+XPCOM_API(nsresult)
+NS_UTF16ToCString(const nsAString& aSrc, nsCStringEncoding aDestEncoding,
+                  nsACString& aDest)
+{
+  if (!xpcomFunctions.utf16ToCString) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return xpcomFunctions.utf16ToCString(aSrc, aDestEncoding, aDest);
+}
+
+XPCOM_API(void*)
+NS_Alloc(size_t aSize)
+{
+  if (!xpcomFunctions.allocFunc) {
+    return nullptr;
+  }
+  return xpcomFunctions.allocFunc(aSize);
+}
+
+XPCOM_API(void*)
+NS_Realloc(void* aPtr, size_t aSize)
+{
+  if (!xpcomFunctions.reallocFunc) {
+    return nullptr;
+  }
+  return xpcomFunctions.reallocFunc(aPtr, aSize);
+}
+
+XPCOM_API(void)
+NS_Free(void* aPtr)
+{
+  if (xpcomFunctions.freeFunc) {
+    xpcomFunctions.freeFunc(aPtr);
+  }
+}
+
+XPCOM_API(void)
+NS_DebugBreak(uint32_t aSeverity, const char* aStr, const char* aExpr,
+              const char* aFile, int32_t aLine)
+{
+  if (xpcomFunctions.debugBreakFunc) {
+    xpcomFunctions.debugBreakFunc(aSeverity, aStr, aExpr, aFile, aLine);
+  }
+}
+
+XPCOM_API(void)
+NS_LogInit()
+{
+  if (xpcomFunctions.logInitFunc) {
+    xpcomFunctions.logInitFunc();
+  }
+}
+
+XPCOM_API(void)
+NS_LogTerm()
+{
+  if (xpcomFunctions.logTermFunc) {
+    xpcomFunctions.logTermFunc();
+  }
+}
+
+XPCOM_API(void)
+NS_LogAddRef(void* aPtr, nsrefcnt aNewRefCnt,
+             const char* aTypeName, uint32_t aInstanceSize)
+{
+  if (xpcomFunctions.logAddRefFunc)
+    xpcomFunctions.logAddRefFunc(aPtr, aNewRefCnt,
+                                 aTypeName, aInstanceSize);
+}
+
+XPCOM_API(void)
+NS_LogRelease(void* aPtr, nsrefcnt aNewRefCnt, const char* aTypeName)
+{
+  if (xpcomFunctions.logReleaseFunc) {
+    xpcomFunctions.logReleaseFunc(aPtr, aNewRefCnt, aTypeName);
+  }
+}
+
+XPCOM_API(void)
+NS_LogCtor(void* aPtr, const char* aTypeName, uint32_t aInstanceSize)
+{
+  if (xpcomFunctions.logCtorFunc) {
+    xpcomFunctions.logCtorFunc(aPtr, aTypeName, aInstanceSize);
+  }
+}
+
+XPCOM_API(void)
+NS_LogDtor(void* aPtr, const char* aTypeName, uint32_t aInstanceSize)
+{
+  if (xpcomFunctions.logDtorFunc) {
+    xpcomFunctions.logDtorFunc(aPtr, aTypeName, aInstanceSize);
+  }
+}
+
+XPCOM_API(void)
+NS_LogCOMPtrAddRef(void* aCOMPtr, nsISupports* aObject)
+{
+  if (xpcomFunctions.logCOMPtrAddRefFunc) {
+    xpcomFunctions.logCOMPtrAddRefFunc(aCOMPtr, aObject);
+  }
+}
+
+XPCOM_API(void)
+NS_LogCOMPtrRelease(void* aCOMPtr, nsISupports* aObject)
+{
+  if (xpcomFunctions.logCOMPtrReleaseFunc) {
+    xpcomFunctions.logCOMPtrReleaseFunc(aCOMPtr, aObject);
+  }
+}
+
+XPCOM_API(nsresult)
+NS_GetXPTCallStub(REFNSIID aIID, nsIXPTCProxy* aOuter,
+                  nsISomeInterface** aStub)
+{
+  if (!xpcomFunctions.getXPTCallStubFunc) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return xpcomFunctions.getXPTCallStubFunc(aIID, aOuter, aStub);
+}
+
+XPCOM_API(void)
+NS_DestroyXPTCallStub(nsISomeInterface* aStub)
+{
+  if (xpcomFunctions.destroyXPTCallStubFunc) {
+    xpcomFunctions.destroyXPTCallStubFunc(aStub);
+  }
+}
+
+XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports* aThat, uint32_t aMethodIndex,
+                 uint32_t aParamCount, nsXPTCVariant* aParams)
+{
+  if (!xpcomFunctions.invokeByIndexFunc) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return xpcomFunctions.invokeByIndexFunc(aThat, aMethodIndex,
+                                          aParamCount, aParams);
+}
+
+XPCOM_API(bool)
+NS_CycleCollectorSuspect(nsISupports* aObj)
+{
+  if (!xpcomFunctions.cycleSuspectFunc) {
+    return false;
+  }
+
+  return xpcomFunctions.cycleSuspectFunc(aObj);
+}
+
+XPCOM_API(bool)
+NS_CycleCollectorForget(nsISupports* aObj)
+{
+  if (!xpcomFunctions.cycleForgetFunc) {
+    return false;
+  }
+
+  return xpcomFunctions.cycleForgetFunc(aObj);
+}
+
+XPCOM_API(nsPurpleBufferEntry*)
+NS_CycleCollectorSuspect2(void* aObj, nsCycleCollectionParticipant* aCp)
+{
+  if (!xpcomFunctions.cycleSuspect2Func) {
+    return nullptr;
+  }
+
+  return xpcomFunctions.cycleSuspect2Func(aObj, aCp);
+}
+
+XPCOM_API(void)
+NS_CycleCollectorSuspect3(void* aObj, nsCycleCollectionParticipant* aCp,
+                          nsCycleCollectingAutoRefCnt* aRefCnt,
+                          bool* aShouldDelete)
+{
+  if (xpcomFunctions.cycleSuspect3Func) {
+    xpcomFunctions.cycleSuspect3Func(aObj, aCp, aRefCnt, aShouldDelete);
+  }
+}
+
+XPCOM_API(bool)
+NS_CycleCollectorForget2(nsPurpleBufferEntry* aEntry)
+{
+  if (!xpcomFunctions.cycleForget2Func) {
+    return false;
+  }
+
+  return xpcomFunctions.cycleForget2Func(aEntry);
+}
diff --git a/xpcom/glue/standalone/nsXPCOMGlue.h b/xpcom/glue/standalone/nsXPCOMGlue.h
new file mode 100644
index 000000000..e23bfa498
--- /dev/null
+++ b/xpcom/glue/standalone/nsXPCOMGlue.h
@@ -0,0 +1,49 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsXPCOMGlue_h__
+#define nsXPCOMGlue_h__
+
+#include "nscore.h"
+
+#ifdef XPCOM_GLUE
+
+/**
+ * The following functions are only available in the standalone glue.
+ */
+
+/**
+ * Enabled preloading of dynamically loaded libraries
+ */
+extern "C" NS_HIDDEN_(void) XPCOMGlueEnablePreload();
+
+/**
+ * Initialize the XPCOM glue by dynamically linking against the XPCOM
+ * shared library indicated by xpcomFile.
+ */
+extern "C" NS_HIDDEN_(nsresult) XPCOMGlueStartup(const char* aXPCOMFile);
+
+typedef void (*NSFuncPtr)();
+
+struct nsDynamicFunctionLoad
+{
+  const char* functionName;
+  NSFuncPtr* function;
+};
+
+/**
+ * Dynamically load functions from libxul.
+ *
+ * @throws NS_ERROR_NOT_INITIALIZED if XPCOMGlueStartup() was not called or
+ *         if the libxul DLL was not found.
+ * @throws NS_ERROR_LOSS_OF_SIGNIFICANT_DATA if only some of the required
+ *         functions were found.
+ */
+extern "C" NS_HIDDEN_(nsresult)
+XPCOMGlueLoadXULFunctions(const nsDynamicFunctionLoad* aSymbols);
+
+#endif // XPCOM_GLUE
+#endif // nsXPCOMGlue_h__
diff --git a/xpcom/glue/standalone/staticruntime/moz.build b/xpcom/glue/standalone/staticruntime/moz.build
new file mode 100644
index 000000000..735086ab0
--- /dev/null
+++ b/xpcom/glue/standalone/staticruntime/moz.build
@@ -0,0 +1,50 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include('../../objs.mozbuild')
+
+SOURCES += xpcom_glue_src_cppsrcs
+
+SOURCES += [
+    '../../nsStringAPI.cpp',
+    '../nsXPCOMGlue.cpp',
+]
+
+Library('xpcomglue_staticruntime')
+
+SDK_LIBRARY = True
+
+# create a static lib
+FORCE_STATIC_LIB = True
+
+if CONFIG['_MSC_VER']:
+    DEFINES['_USE_ANSI_CPP'] = True
+    # Don't include directives about which CRT to use
+    CFLAGS += ['-Zl']
+    CXXFLAGS += ['-Zl']
+
+DEFINES['XPCOM_GLUE'] = True
+
+LOCAL_INCLUDES += [
+    '../../../build',
+    '../../../threads',
+]
+
+# Statically link to the CRT on Windows
+USE_STATIC_LIBS = True
+
+# Don't use STL wrappers here (i.e. wrapped <new>); they require mozalloc
+DISABLE_STL_WRAPPING = True
+
+# Include fallible for third party code using the xpcom glue
+USE_LIBS += [
+    'fallible',
+]
+
+# Force to build a static library only
+NO_EXPAND_LIBS = True
+
+DIST_INSTALL = True
diff --git a/xpcom/glue/staticruntime/moz.build b/xpcom/glue/staticruntime/moz.build
new file mode 100644
index 000000000..384bc6878
--- /dev/null
+++ b/xpcom/glue/staticruntime/moz.build
@@ -0,0 +1,48 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include('../objs.mozbuild')
+
+UNIFIED_SOURCES += xpcom_gluens_src_cppsrcs
+UNIFIED_SOURCES += xpcom_glue_src_cppsrcs
+
+UNIFIED_SOURCES += [
+    '../GenericModule.cpp',
+    '../nsStringAPI.cpp',
+]
+
+Library('xpcomglue_staticruntime_s')
+
+SDK_LIBRARY = True
+
+FORCE_STATIC_LIB = True
+
+if CONFIG['_MSC_VER']:
+    DEFINES['_USE_ANSI_CPP'] = True
+    # Don't include directives about which CRT to use
+    CFLAGS += ['-Zl']
+    CXXFLAGS += ['-Zl']
+
+LOCAL_INCLUDES += [
+    '../../build',
+    '../../threads',
+]
+
+# Statically link to the CRT on Windows
+USE_STATIC_LIBS = True
+
+# Don't use STL wrappers here (i.e. wrapped <new>); they require mozalloc
+DISABLE_STL_WRAPPING = True
+
+# Include fallible for third party code using the xpcom glue
+USE_LIBS += [
+    'fallible',
+]
+
+# Force to build a static library only
+NO_EXPAND_LIBS = True
+
+DIST_INSTALL = True
diff --git a/xpcom/glue/tests/gtest/TestArray.cpp b/xpcom/glue/tests/gtest/TestArray.cpp
new file mode 100644
index 000000000..72d28b4df
--- /dev/null
+++ b/xpcom/glue/tests/gtest/TestArray.cpp
@@ -0,0 +1,169 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "gtest/gtest.h"
+
+// Disable deprecation warnings generated by nsISupportsArray and associated
+// classes.
+#if defined(__GNUC__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+#elif defined(_MSC_VER)
+#pragma warning (push)
+#pragma warning (disable : 4996)
+#endif
+
+#include "nsISupportsArray.h"
+
+// {9e70a320-be02-11d1-8031-006008159b5a}
+#define NS_IFOO_IID \
+  {0x9e70a320, 0xbe02, 0x11d1,    \
+    {0x80, 0x31, 0x00, 0x60, 0x08, 0x15, 0x9b, 0x5a}}
+
+namespace TestArray {
+
+class IFoo : public nsISupports {
+public:
+
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_IFOO_IID)
+
+  NS_IMETHOD_(nsrefcnt) RefCnt() = 0;
+  NS_IMETHOD_(int32_t) ID() = 0;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(IFoo, NS_IFOO_IID)
+
+class Foo final : public IFoo {
+public:
+
+  explicit Foo(int32_t aID);
+
+  // nsISupports implementation
+  NS_DECL_ISUPPORTS
+
+  // IFoo implementation
+  NS_IMETHOD_(nsrefcnt) RefCnt() override { return mRefCnt; }
+  NS_IMETHOD_(int32_t) ID() override { return mID; }
+
+  static int32_t gCount;
+
+  int32_t mID;
+
+private:
+  ~Foo();
+};
+
+int32_t Foo::gCount;
+
+Foo::Foo(int32_t aID)
+{
+  mID = aID;
+  ++gCount;
+}
+
+Foo::~Foo()
+{
+  --gCount;
+}
+
+NS_IMPL_ISUPPORTS(Foo, IFoo)
+
+void CheckArray(nsISupportsArray* aArray, int32_t aExpectedCount, int32_t aElementIDs[], int32_t aExpectedTotal)
+{
+  uint32_t cnt = 0;
+#ifdef DEBUG
+  nsresult rv =
+#endif
+    aArray->Count(&cnt);
+  NS_ASSERTION(NS_SUCCEEDED(rv), "Count failed");
+  int32_t count = cnt;
+  int32_t index;
+
+  EXPECT_EQ(Foo::gCount, aExpectedTotal);
+  EXPECT_EQ(count, aExpectedCount);
+
+  for (index = 0; (index < count) && (index < aExpectedCount); index++) {
+    nsCOMPtr<IFoo> foo = do_QueryElementAt(aArray, index);
+    EXPECT_EQ(foo->ID(), aElementIDs[index]);
+  }
+}
+
+void FillArray(nsISupportsArray* aArray, int32_t aCount)
+{
+  int32_t index;
+  for (index = 0; index < aCount; index++) {
+    nsCOMPtr<IFoo> foo = new Foo(index);
+    aArray->AppendElement(foo);
+  }
+}
+
+} // namespace TestArray
+
+using namespace TestArray;
+
+TEST(Array, main)
+{
+  nsISupportsArray* array;
+  nsresult  rv;
+
+  if (NS_OK == (rv = NS_NewISupportsArray(&array))) {
+    FillArray(array, 10);
+    int32_t   fillResult[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
+    CheckArray(array, 10, fillResult, 10);
+
+    // test insert
+    nsCOMPtr<IFoo> foo = do_QueryElementAt(array, 3);
+    array->InsertElementAt(foo, 5);
+    int32_t   insertResult[11] = {0, 1, 2, 3, 4, 3, 5, 6, 7, 8, 9};
+    CheckArray(array, 11, insertResult, 10);
+    array->InsertElementAt(foo, 0);
+    int32_t   insertResult2[12] = {3, 0, 1, 2, 3, 4, 3, 5, 6, 7, 8, 9};
+    CheckArray(array, 12, insertResult2, 10);
+    array->AppendElement(foo);
+    int32_t   appendResult[13] = {3, 0, 1, 2, 3, 4, 3, 5, 6, 7, 8, 9, 3};
+    CheckArray(array, 13, appendResult, 10);
+
+
+    // test IndexOf
+    int32_t expectedIndex = 0;
+    int32_t index = array->IndexOf(foo);
+    EXPECT_EQ(index, expectedIndex);
+
+    // test ReplaceElementAt
+    array->ReplaceElementAt(foo, 8);
+    int32_t   replaceResult[13] = {3, 0, 1, 2, 3, 4, 3, 5, 3, 7, 8, 9, 3};
+    CheckArray(array, 13, replaceResult, 9);
+
+    // test RemoveElementAt, RemoveElement
+    array->RemoveElementAt(0);
+    int32_t   removeResult[12] = {0, 1, 2, 3, 4, 3, 5, 3, 7, 8, 9, 3};
+    CheckArray(array, 12, removeResult, 9);
+    array->RemoveElementAt(7);
+    int32_t   removeResult2[11] = {0, 1, 2, 3, 4, 3, 5, 7, 8, 9, 3};
+    CheckArray(array, 11, removeResult2, 9);
+    array->RemoveElement(foo);
+    int32_t   removeResult3[10] = {0, 1, 2, 4, 3, 5, 7, 8, 9, 3};
+    CheckArray(array, 10, removeResult3, 9);
+
+    foo = nullptr;
+
+    // test clear
+    array->Clear();
+    FillArray(array, 4);
+    CheckArray(array, 4, fillResult, 4);
+
+    // test delete
+    NS_RELEASE(array);
+  }
+}
+
+#if defined(__GNUC__)
+#pragma GCC diagnostic pop
+#elif defined(_MSC_VER)
+#pragma warning (pop)
+#endif
diff --git a/xpcom/glue/tests/gtest/TestFileUtils.cpp b/xpcom/glue/tests/gtest/TestFileUtils.cpp
new file mode 100644
index 000000000..55106c6c5
--- /dev/null
+++ b/xpcom/glue/tests/gtest/TestFileUtils.cpp
@@ -0,0 +1,283 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+/* Test ReadSysFile() */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "FileUtils.h"
+
+#include "gtest/gtest.h"
+
+namespace mozilla {
+
+#ifdef ReadSysFile_PRESENT
+
+/**
+ * Create a file with the specified contents.
+ */
+static bool
+WriteFile(
+  const char* aFilename,
+  const void* aContents,
+  size_t aContentsLen)
+{
+  int fd;
+  ssize_t ret;
+  size_t offt;
+
+  fd = MOZ_TEMP_FAILURE_RETRY(
+    open(aFilename, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR));
+  if (fd == -1) {
+    fprintf(stderr, "open(): %s: %s\n", aFilename, strerror(errno));
+    return false;
+  }
+
+  offt = 0;
+  do {
+    ret = MOZ_TEMP_FAILURE_RETRY(
+      write(fd, (char*)aContents + offt, aContentsLen - offt));
+    if (ret == -1) {
+      fprintf(stderr, "write(): %s: %s\n", aFilename, strerror(errno));
+      close(fd);
+      return false;
+    }
+    offt += ret;
+  } while (offt < aContentsLen);
+
+  ret = MOZ_TEMP_FAILURE_RETRY(close(fd));
+  if (ret == -1) {
+    fprintf(stderr, "close(): %s: %s\n", aFilename, strerror(errno));
+    return false;
+  }
+  return true;
+}
+
+TEST(ReadSysFile, Nonexistent) {
+  bool ret;
+  int errno_saved;
+
+  ret = ReadSysFile("/nonexistent", nullptr, 0);
+  errno_saved = errno;
+
+  ASSERT_FALSE(ret);
+  ASSERT_EQ(errno_saved, ENOENT);
+}
+
+TEST(ReadSysFile, Main) {
+  /* Use a different file name for each test since different tests could be
+  executed concurrently. */
+  static const char* fn = "TestReadSysFileMain";
+  /* If we have a file which contains "abcd" and we read it with ReadSysFile(),
+  providing a buffer of size 10 bytes, we would expect 5 bytes to be written
+  to that buffer: "abcd\0". */
+  struct
+  {
+    /* input (file contents), e.g. "abcd" */
+    const char* input;
+    /* pretended output buffer size, e.g. 10; the actual buffer is larger
+    and we check if anything was written past the end of the allowed length */
+    size_t output_size;
+    /* expected number of bytes written to the output buffer, including the
+    terminating '\0', e.g. 5 */
+    size_t output_len;
+    /* expected output buffer contents, e.g. "abcd\0", the first output_len
+    bytes of the output buffer should match the first 'output_len' bytes from
+    'output', the rest of the output buffer should be untouched. */
+    const char* output;
+  } tests[] = {
+    /* No new lines */
+    {"", 0, 0, ""},
+    {"", 1, 1, "\0"}, /* \0 is redundant, but we write it for clarity */
+    {"", 9, 1, "\0"},
+
+    {"a", 0, 0, ""},
+    {"a", 1, 1, "\0"},
+    {"a", 2, 2, "a\0"},
+    {"a", 9, 2, "a\0"},
+
+    {"abcd", 0, 0, ""},
+    {"abcd", 1, 1, "\0"},
+    {"abcd", 2, 2, "a\0"},
+    {"abcd", 3, 3, "ab\0"},
+    {"abcd", 4, 4, "abc\0"},
+    {"abcd", 5, 5, "abcd\0"},
+    {"abcd", 9, 5, "abcd\0"},
+
+    /* A single trailing new line */
+    {"\n", 0, 0, ""},
+    {"\n", 1, 1, "\0"},
+    {"\n", 2, 1, "\0"},
+    {"\n", 9, 1, "\0"},
+
+    {"a\n", 0, 0, ""},
+    {"a\n", 1, 1, "\0"},
+    {"a\n", 2, 2, "a\0"},
+    {"a\n", 3, 2, "a\0"},
+    {"a\n", 9, 2, "a\0"},
+
+    {"abcd\n", 0, 0, ""},
+    {"abcd\n", 1, 1, "\0"},
+    {"abcd\n", 2, 2, "a\0"},
+    {"abcd\n", 3, 3, "ab\0"},
+    {"abcd\n", 4, 4, "abc\0"},
+    {"abcd\n", 5, 5, "abcd\0"},
+    {"abcd\n", 6, 5, "abcd\0"},
+    {"abcd\n", 9, 5, "abcd\0"},
+
+    /* Multiple trailing new lines */
+    {"\n\n", 0, 0, ""},
+    {"\n\n", 1, 1, "\0"},
+    {"\n\n", 2, 2, "\n\0"},
+    {"\n\n", 3, 2, "\n\0"},
+    {"\n\n", 9, 2, "\n\0"},
+
+    {"a\n\n", 0, 0, ""},
+    {"a\n\n", 1, 1, "\0"},
+    {"a\n\n", 2, 2, "a\0"},
+    {"a\n\n", 3, 3, "a\n\0"},
+    {"a\n\n", 4, 3, "a\n\0"},
+    {"a\n\n", 9, 3, "a\n\0"},
+
+    {"abcd\n\n", 0, 0, ""},
+    {"abcd\n\n", 1, 1, "\0"},
+    {"abcd\n\n", 2, 2, "a\0"},
+    {"abcd\n\n", 3, 3, "ab\0"},
+    {"abcd\n\n", 4, 4, "abc\0"},
+    {"abcd\n\n", 5, 5, "abcd\0"},
+    {"abcd\n\n", 6, 6, "abcd\n\0"},
+    {"abcd\n\n", 7, 6, "abcd\n\0"},
+    {"abcd\n\n", 9, 6, "abcd\n\0"},
+
+    /* New line in the middle */
+    {"ab\ncd", 9, 6, "ab\ncd\0"},
+  };
+
+  for (size_t i = 0; i < sizeof(tests) / sizeof(tests[0]); i++) {
+    ASSERT_TRUE(WriteFile(fn, tests[i].input, strlen(tests[i].input)));
+    /* Leave the file to exist if some of the assertions fail. */
+
+    char buf[128];
+    static const char unmodified = 'X';
+
+    memset(buf, unmodified, sizeof(buf));
+
+    ASSERT_TRUE(ReadSysFile(fn, buf, tests[i].output_size));
+
+    if (tests[i].output_size == 0) {
+      /* The buffer must be unmodified. We check only the first byte. */
+      ASSERT_EQ(unmodified, buf[0]);
+    } else {
+      ASSERT_EQ(tests[i].output_len, strlen(buf) + 1);
+      ASSERT_STREQ(tests[i].output, buf);
+      /* Check that the first byte after the trailing '\0' has not been
+      modified. */
+      ASSERT_EQ(unmodified, buf[tests[i].output_len]);
+    }
+  }
+
+  unlink(fn);
+}
+
+TEST(ReadSysFile, Int) {
+  static const char* fn = "TestReadSysFileInt";
+  struct
+  {
+    /* input (file contents), e.g. "5" */
+    const char* input;
+    /* expected return value, if false, then the output is not checked */
+    bool ret;
+    /* expected result */
+    int output;
+  } tests[] = {
+    {"0", true, 0},
+    {"00", true, 0},
+    {"1", true, 1},
+    {"5", true, 5},
+    {"55", true, 55},
+
+    {" 123", true, 123},
+    {"123 ", true, 123},
+    {" 123 ", true, 123},
+    {"123\n", true, 123},
+
+    {"", false, 0},
+    {" ", false, 0},
+    {"a", false, 0},
+
+    {"-1", true, -1},
+    {" -456 ", true, -456},
+    {" -78.9 ", true, -78},
+  };
+
+  for (size_t i = 0; i < sizeof(tests) / sizeof(tests[0]); i++) {
+    ASSERT_TRUE(WriteFile(fn, tests[i].input, strlen(tests[i].input)));
+    /* Leave the file to exist if some of the assertions fail. */
+
+    bool ret;
+    int output = 424242;
+
+    ret = ReadSysFile(fn, &output);
+
+    ASSERT_EQ(tests[i].ret, ret);
+
+    if (ret) {
+      ASSERT_EQ(tests[i].output, output);
+    }
+  }
+
+  unlink(fn);
+}
+
+TEST(ReadSysFile, Bool) {
+  static const char* fn = "TestReadSysFileBool";
+  struct
+  {
+    /* input (file contents), e.g. "1" */
+    const char* input;
+    /* expected return value */
+    bool ret;
+    /* expected result */
+    bool output;
+  } tests[] = {
+    {"0", true, false},
+    {"00", true, false},
+    {"1", true, true},
+    {"5", true, true},
+    {"23", true, true},
+    {"-1", true, true},
+
+    {"", false, true /* unused */},
+  };
+
+  for (size_t i = 0; i < sizeof(tests) / sizeof(tests[0]); i++) {
+    ASSERT_TRUE(WriteFile(fn, tests[i].input, strlen(tests[i].input)));
+    /* Leave the file to exist if some of the assertions fail. */
+
+    bool ret;
+    bool output;
+
+    ret = ReadSysFile(fn, &output);
+
+    ASSERT_EQ(tests[i].ret, ret);
+
+    if (ret) {
+      ASSERT_EQ(tests[i].output, output);
+    }
+  }
+
+  unlink(fn);
+}
+
+#endif /* ReadSysFile_PRESENT */
+
+} // namespace mozilla
diff --git a/xpcom/glue/tests/gtest/TestGCPostBarriers.cpp b/xpcom/glue/tests/gtest/TestGCPostBarriers.cpp
new file mode 100644
index 000000000..5bf10ab05
--- /dev/null
+++ b/xpcom/glue/tests/gtest/TestGCPostBarriers.cpp
@@ -0,0 +1,140 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Tests that generational garbage collection post-barriers are correctly
+ * implemented for nsTArrays that contain JavaScript Values.
+ */
+
+#include "jsapi.h"
+#include "nsTArray.h"
+
+#include "gtest/gtest.h"
+
+#include "js/TracingAPI.h"
+#include "js/HeapAPI.h"
+
+#include "mozilla/CycleCollectedJSContext.h"
+
+using namespace JS;
+using namespace mozilla;
+
+template<class ArrayT>
+static void
+TraceArray(JSTracer* trc, void* data)
+{
+  ArrayT* array = static_cast<ArrayT *>(data);
+  for (unsigned i = 0; i < array->Length(); ++i)
+    JS::TraceEdge(trc, &array->ElementAt(i), "array-element");
+}
+
+/*
+ * Use arrays with initial size much smaller than the final number of elements
+ * to test that moving Heap<T> elements works correctly.
+ */
+const size_t ElementCount = 100;
+const size_t InitialElements = ElementCount / 10;
+
+template<class ArrayT>
+static void
+RunTest(JSContext* cx, ArrayT* array)
+{
+  JS_GC(cx);
+
+  ASSERT_TRUE(array != nullptr);
+  JS_AddExtraGCRootsTracer(cx, TraceArray<ArrayT>, array);
+
+  /*
+   * Create the array and fill it with new JS objects. With GGC these will be
+   * allocated in the nursery.
+   */
+  RootedValue value(cx);
+  const char* property = "foo";
+  for (size_t i = 0; i < ElementCount; ++i) {
+    RootedObject obj(cx, JS_NewPlainObject(cx));
+    ASSERT_FALSE(JS::ObjectIsTenured(obj));
+    value = Int32Value(i);
+    ASSERT_TRUE(JS_SetProperty(cx, obj, property, value));
+    ASSERT_TRUE(array->AppendElement(obj, fallible));
+  }
+
+  /*
+   * If postbarriers are not working, we will crash here when we try to mark
+   * objects that have been moved to the tenured heap.
+   */
+  JS_GC(cx);
+
+  /*
+   * Sanity check that our array contains what we expect.
+   */
+  for (size_t i = 0; i < ElementCount; ++i) {
+    RootedObject obj(cx, array->ElementAt(i));
+    ASSERT_TRUE(JS::ObjectIsTenured(obj));
+    ASSERT_TRUE(JS_GetProperty(cx, obj, property, &value));
+    ASSERT_TRUE(value.isInt32());
+    ASSERT_EQ(static_cast<int32_t>(i), value.toInt32());
+  }
+
+  JS_RemoveExtraGCRootsTracer(cx, TraceArray<ArrayT>, array);
+}
+
+static void
+CreateGlobalAndRunTest(JSContext* cx)
+{
+  static const JSClassOps GlobalClassOps = {
+    nullptr, nullptr, nullptr, nullptr,
+    nullptr, nullptr, nullptr, nullptr,
+    nullptr, nullptr, nullptr,
+    JS_GlobalObjectTraceHook
+  };
+
+  static const JSClass GlobalClass = {
+    "global", JSCLASS_GLOBAL_FLAGS,
+    &GlobalClassOps
+  };
+
+  JS::CompartmentOptions options;
+  options.behaviors().setVersion(JSVERSION_LATEST);
+  JS::PersistentRootedObject global(cx);
+  global = JS_NewGlobalObject(cx, &GlobalClass, nullptr, JS::FireOnNewGlobalHook, options);
+  ASSERT_TRUE(global != nullptr);
+
+  JSCompartment *oldCompartment = JS_EnterCompartment(cx, global);
+
+  typedef Heap<JSObject*> ElementT;
+
+  {
+    nsTArray<ElementT>* array = new nsTArray<ElementT>(InitialElements);
+    RunTest(cx, array);
+    delete array;
+  }
+
+  {
+    FallibleTArray<ElementT>* array = new FallibleTArray<ElementT>(InitialElements);
+    RunTest(cx, array);
+    delete array;
+  }
+
+  {
+    AutoTArray<ElementT, InitialElements> array;
+    RunTest(cx, &array);
+  }
+
+  JS_LeaveCompartment(cx, oldCompartment);
+}
+
+TEST(GCPostBarriers, nsTArray) {
+  CycleCollectedJSContext* ccjscx = CycleCollectedJSContext::Get();
+  ASSERT_TRUE(ccjscx != nullptr);
+  JSContext* cx = ccjscx->Context();
+  ASSERT_TRUE(cx != nullptr);
+
+  JS_BeginRequest(cx);
+
+  CreateGlobalAndRunTest(cx);
+
+  JS_EndRequest(cx);
+}
diff --git a/xpcom/glue/tests/gtest/TestNsDeque.cpp b/xpcom/glue/tests/gtest/TestNsDeque.cpp
new file mode 100644
index 000000000..b84e1b781
--- /dev/null
+++ b/xpcom/glue/tests/gtest/TestNsDeque.cpp
@@ -0,0 +1,342 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "gtest/gtest.h"
+#include "nsDeque.h"
+#include "nsCRT.h"
+#include <stdio.h>
+
+/**************************************************************
+  Now define the token deallocator class...
+ **************************************************************/
+namespace TestNsDeque {
+  
+  class _Dealloc: public nsDequeFunctor 
+  {
+    virtual void* operator()(void* aObject) {
+      return 0;
+    }
+  };
+
+  static bool VerifyContents(const nsDeque& aDeque, const int* aContents, size_t aLength) 
+  {
+    for (size_t i=0; i<aLength; ++i) {
+      if (*(int*)aDeque.ObjectAt(i) != aContents[i]) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  class Deallocator: public nsDequeFunctor
+  {
+    virtual void* operator()(void* aObject) 
+    {
+      if (aObject) 
+      {
+        // Set value to -1, to use in test function.
+        *((int*)aObject) = -1;
+      }
+
+      return nullptr;
+    }
+  };
+
+  class ForEachAdder: public nsDequeFunctor
+  {
+    virtual void* operator()(void* aObject) 
+    {
+      if (aObject) 
+      {
+        sum += *(int*)aObject;
+      }
+
+      return aObject;
+    }
+
+    private:
+     int sum = 0;
+    
+    public:
+     int GetSum() { return sum; }
+    
+  };
+}
+
+using namespace TestNsDeque;
+
+TEST(NsDeque, OriginalTest)
+{
+  const size_t size = 200;
+  int ints[size];
+  size_t i=0;
+  int temp;
+  nsDeque theDeque(new _Dealloc); //construct a simple one...
+ 
+  // ints = [0...199]
+  for (i=0;i<size;i++) { //initialize'em
+    ints[i]=static_cast<int>(i);
+  }
+  // queue = [0...69]
+  for (i=0;i<70;i++) {
+    theDeque.Push(&ints[i]);
+    temp=*(int*)theDeque.Peek();
+    EXPECT_EQ(static_cast<int>(i), temp) << "Verify end after push #1";
+    EXPECT_EQ(i + 1, theDeque.GetSize()) << "Verify size after push #1";
+  }
+
+  EXPECT_EQ(70u,theDeque.GetSize()) << "Verify overall size after pushes #1";
+
+  // queue = [0...14]
+  for (i=1;i<=55;i++) {
+    temp=*(int*)theDeque.Pop();
+    EXPECT_EQ(70-static_cast<int>(i),temp) << "Verify end after pop # 1";
+    EXPECT_EQ(70u - i,theDeque.GetSize()) << "Verify size after pop # 1";
+  }
+  EXPECT_EQ(15u,theDeque.GetSize()) << "Verify overall size after pops";
+
+  // queue = [0...14,0...54]
+  for (i=0;i<55;i++) {
+    theDeque.Push(&ints[i]);
+    temp=*(int*)theDeque.Peek();
+    EXPECT_EQ(static_cast<int>(i),temp) << "Verify end after push #2";
+    EXPECT_EQ(i + 15u + 1,theDeque.GetSize()) << "Verify size after push # 2";
+  }
+  EXPECT_EQ(70u,theDeque.GetSize()) << "Verify size after end of all pushes #2";
+
+  // queue = [0...14,0...19]
+  for (i=1;i<=35;i++) {
+    temp=*(int*)theDeque.Pop();
+    EXPECT_EQ(55-static_cast<int>(i),temp ) << "Verify end after pop # 2";
+    EXPECT_EQ(70u - i,theDeque.GetSize()) << "Verify size after pop #2";
+  }
+  EXPECT_EQ(35u,theDeque.GetSize()) << "Verify overall size after end of all pops #2";
+
+  // queue = [0...14,0...19,0...34]
+  for (i=0;i<35;i++) {
+    theDeque.Push(&ints[i]);
+    temp = *(int*)theDeque.Peek();
+    EXPECT_EQ(static_cast<int>(i),temp) << "Verify end after push # 3";
+    EXPECT_EQ(35u + 1u + i,theDeque.GetSize()) << "Verify size after push #3";
+  }
+
+  // queue = [0...14,0...19]
+  for (i=0;i<35;i++) {
+    temp=*(int*)theDeque.Pop();
+    EXPECT_EQ(34 - static_cast<int>(i), temp) << "Verify end after pop # 3";
+  }
+
+  // queue = [0...14]
+  for (i=0;i<20;i++) {
+    temp=*(int*)theDeque.Pop();
+    EXPECT_EQ(19 - static_cast<int>(i),temp) << "Verify end after pop # 4";
+  }
+
+  // queue = []
+  for (i=0;i<15;i++) {
+    temp=*(int*)theDeque.Pop();
+    EXPECT_EQ(14 - static_cast<int>(i),temp) << "Verify end after pop # 5";
+  }
+
+  EXPECT_EQ(0u,theDeque.GetSize()) << "Deque should finish empty.";
+}
+
+TEST(NsDeque, OriginalFlaw)
+{
+  int ints[200];
+  int i=0;
+  int temp;
+  nsDeque d(new _Dealloc);
+  /**
+   * Test 1. Origin near end, semi full, call Peek().
+   * you start, mCapacity is 8
+   */
+  for (i=0; i<30; i++)
+    ints[i]=i;
+
+  for (i=0; i<6; i++) {
+    d.Push(&ints[i]);
+    temp = *(int*)d.Peek();
+    EXPECT_EQ(i, temp) << "OriginalFlaw push #1";
+  }
+  EXPECT_EQ(6u, d.GetSize()) << "OriginalFlaw size check #1";
+
+  for (i=0; i<4; i++) {
+    temp=*(int*)d.PopFront();
+    EXPECT_EQ(i, temp) << "PopFront test";
+  }
+  // d = [4,5]
+  EXPECT_EQ(2u, d.GetSize()) << "OriginalFlaw size check #2";
+
+  for (i=0; i<4; i++) {
+    d.Push(&ints[6 + i]);
+  }
+
+  // d = [4...9]
+  for (i=4; i<=9; i++) {
+    temp=*(int*)d.PopFront();
+    EXPECT_EQ(i, temp) << "OriginalFlaw empty check";
+  }
+}
+
+TEST(NsDeque, TestObjectAt)
+{
+  nsDeque d;
+  const int count = 10;
+  int ints[count];
+  for (int i=0; i<count; i++) {
+    ints[i] = i;
+  }
+
+  for (int i=0; i<6; i++) {
+    d.Push(&ints[i]);
+  }
+  // d = [0...5]
+  d.PopFront();
+  d.PopFront();
+
+  // d = [2..5]
+  for (size_t i=2; i<=5; i++) {
+    int t = *(int*)d.ObjectAt(i-2);
+    EXPECT_EQ(static_cast<int>(i),t) << "Verify ObjectAt()";
+  }
+}
+
+TEST(NsDeque, TestPushFront)
+{
+  // PushFront has some interesting corner cases, primarily we're interested in whether:
+  // - wrapping around works properly
+  // - growing works properly
+
+  nsDeque d;
+
+  const int kPoolSize = 10;
+  const size_t kMaxSizeBeforeGrowth = 8;
+
+  int pool[kPoolSize];
+  for (int i = 0; i < kPoolSize; i++) {
+    pool[i] = i;
+  }
+
+  for (size_t i = 0; i < kMaxSizeBeforeGrowth; i++) {
+    d.PushFront(pool + i);
+  }
+
+  EXPECT_EQ(kMaxSizeBeforeGrowth, d.GetSize()) << "verify size";
+
+  static const int t1[] = {7,6,5,4,3,2,1,0};
+  EXPECT_TRUE(VerifyContents(d, t1, kMaxSizeBeforeGrowth)) << "verify pushfront 1";
+
+  // Now push one more so it grows
+  d.PushFront(pool + kMaxSizeBeforeGrowth);
+  EXPECT_EQ(kMaxSizeBeforeGrowth + 1, d.GetSize()) << "verify size";
+
+  static const int t2[] = {8,7,6,5,4,3,2,1,0};
+  EXPECT_TRUE(VerifyContents(d, t2, kMaxSizeBeforeGrowth + 1)) << "verify pushfront 2";
+
+  // And one more so that it wraps again
+  d.PushFront(pool + kMaxSizeBeforeGrowth + 1);
+  EXPECT_EQ(kMaxSizeBeforeGrowth + 2, d.GetSize()) << "verify size";
+
+  static const int t3[] = {9,8,7,6,5,4,3,2,1,0};
+  EXPECT_TRUE(VerifyContents(d, t3, kMaxSizeBeforeGrowth + 2)) <<"verify pushfront 3";
+}
+
+void CheckIfQueueEmpty(nsDeque& d)
+{
+  EXPECT_EQ(0u, d.GetSize())         << "Size should be 0";
+  EXPECT_EQ(nullptr, d.Pop())       <<  "Invalid operation should return nullptr";
+  EXPECT_EQ(nullptr, d.PopFront())  <<  "Invalid operation should return nullptr";
+  EXPECT_EQ(nullptr, d.Peek())      <<  "Invalid operation should return nullptr";
+  EXPECT_EQ(nullptr, d.PeekFront()) <<  "Invalid operation should return nullptr";
+  EXPECT_EQ(nullptr, d.ObjectAt(0u)) <<  "Invalid operation should return nullptr";
+}
+
+TEST(NsDeque,TestEmpty)
+{
+  // Make sure nsDeque gives sane results if it's empty.
+  nsDeque d;
+  size_t numberOfEntries = 8;
+
+  CheckIfQueueEmpty(d);
+
+  // Fill it up and drain it.
+  for (size_t i = 0; i < numberOfEntries; i++) {
+    d.Push((void*)0xAA);
+  }
+
+  EXPECT_EQ(numberOfEntries, d.GetSize());
+
+  for (size_t i = 0; i < numberOfEntries; i++) {
+    (void)d.Pop();
+  }
+
+  // Now check it again.
+  CheckIfQueueEmpty(d);
+}
+
+TEST(NsDeque,TestEraseMethod)
+{
+  nsDeque d;
+  const size_t numberOfEntries = 8;
+
+  // Fill it up before calling Erase
+  for (size_t i = 0; i < numberOfEntries; i++) {
+    d.Push((void*)0xAA);
+  }
+
+  // Call Erase
+  d.Erase();
+
+  // Now check it again.
+  CheckIfQueueEmpty(d);
+}
+
+TEST(NsDeque,TestEraseShouldCallDeallocator)
+{
+  nsDeque d(new Deallocator());
+  const size_t NumTestValues = 8;
+
+  int* testArray[NumTestValues];
+  for (size_t i=0; i < NumTestValues; i++)
+  {
+    testArray[i] = new int();
+    *(testArray[i]) = i;
+    d.Push((void*)testArray[i]);
+  }
+
+  d.Erase();
+
+  // Now check it again.
+  CheckIfQueueEmpty(d);
+  
+  for (size_t i=0; i < NumTestValues; i++)
+  {
+    EXPECT_EQ(-1, *(testArray[i])) << "Erase should call deallocator: " << *(testArray[i]);
+  }
+}
+
+TEST(NsDeque, TestForEach)
+{
+  nsDeque d(new Deallocator());
+  const size_t NumTestValues = 8;
+  int sum = 0;
+
+  int* testArray[NumTestValues];
+  for (size_t i=0; i < NumTestValues; i++)
+  {
+    testArray[i] = new int();
+    *(testArray[i]) = i;
+    sum += i;
+    d.Push((void*)testArray[i]);
+  }
+
+  ForEachAdder adder;
+  d.ForEach(adder);
+  EXPECT_EQ(sum, adder.GetSum()) << "For each should iterate over values";
+
+  d.Erase();
+}
diff --git a/xpcom/glue/tests/gtest/TestThreadUtils.cpp b/xpcom/glue/tests/gtest/TestThreadUtils.cpp
new file mode 100644
index 000000000..728bae612
--- /dev/null
+++ b/xpcom/glue/tests/gtest/TestThreadUtils.cpp
@@ -0,0 +1,937 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "nsThreadUtils.h"
+#include "gtest/gtest.h"
+
+// {9e70a320-be02-11d1-8031-006008159b5a}
+#define NS_IFOO_IID \
+  {0x9e70a320, 0xbe02, 0x11d1,    \
+    {0x80, 0x31, 0x00, 0x60, 0x08, 0x15, 0x9b, 0x5a}}
+
+namespace TestThreadUtils {
+
+static bool gDebug = false;
+static int gAlive, gZombies;
+static int gAllConstructions, gConstructions, gCopyConstructions,
+           gMoveConstructions, gDestructions, gAssignments, gMoves;
+struct Spy
+{
+  static void ClearActions()
+  {
+    gAllConstructions = gConstructions = gCopyConstructions
+        = gMoveConstructions = gDestructions = gAssignments = gMoves = 0;
+  }
+  static void ClearAll()
+  {
+    ClearActions();
+    gAlive = 0;
+  }
+
+  explicit Spy(int aID) : mID(aID)
+  {
+    ++gAlive; ++gAllConstructions; ++gConstructions;
+    if (gDebug) { printf("Spy[%d@%p]()\n", mID, this); }
+  }
+  Spy(const Spy& o) : mID(o.mID)
+  {
+    ++gAlive; ++gAllConstructions; ++gCopyConstructions;
+    if (gDebug) { printf("Spy[%d@%p](&[%d@%p])\n", mID, this, o.mID, &o); }
+  }
+  Spy(Spy&& o) : mID(o.mID)
+  {
+    o.mID = -o.mID;
+    ++gZombies; ++gAllConstructions; ++gMoveConstructions;
+    if (gDebug) { printf("Spy[%d@%p](&&[%d->%d@%p])\n", mID, this, -o.mID, o.mID, &o); }
+  }
+  ~Spy()
+  {
+    if (mID >= 0) { --gAlive; } else { --gZombies; } ++gDestructions;
+    if (gDebug) { printf("~Spy[%d@%p]()\n", mID, this); }
+    mID = 0;
+  }
+  Spy& operator=(const Spy& o)
+  {
+    ++gAssignments;
+    if (gDebug) { printf("Spy[%d->%d@%p] = &[%d@%p]\n", mID, o.mID, this, o.mID, &o); }
+    mID = o.mID;
+    return *this;
+  };
+  Spy& operator=(Spy&& o)
+  {
+    --gAlive; ++gZombies;
+    ++gMoves;
+    if (gDebug) { printf("Spy[%d->%d@%p] = &&[%d->%d@%p]\n", mID, o.mID, this, o.mID, -o.mID, &o); }
+    mID = o.mID; o.mID = -o.mID;
+    return *this;
+  };
+
+  int mID; // ID given at construction, or negation if was moved from; 0 when destroyed.
+};
+
+struct ISpyWithISupports : public nsISupports
+{
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_IFOO_IID)
+  NS_IMETHOD_(nsrefcnt) RefCnt() = 0;
+  NS_IMETHOD_(int32_t) ID() = 0;
+};
+NS_DEFINE_STATIC_IID_ACCESSOR(ISpyWithISupports, NS_IFOO_IID)
+struct SpyWithISupports : public ISpyWithISupports, public Spy
+{
+private:
+  virtual ~SpyWithISupports() = default;
+public:
+  explicit SpyWithISupports(int aID) : Spy(aID) {};
+  NS_DECL_ISUPPORTS
+  NS_IMETHOD_(nsrefcnt) RefCnt() override { return mRefCnt; }
+  NS_IMETHOD_(int32_t) ID() override { return mID; }
+};
+NS_IMPL_ISUPPORTS(SpyWithISupports, ISpyWithISupports)
+
+
+class IThreadUtilsObject : public nsISupports
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_IFOO_IID)
+
+  NS_IMETHOD_(nsrefcnt) RefCnt() = 0;
+  NS_IMETHOD_(int32_t) ID() = 0;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(IThreadUtilsObject, NS_IFOO_IID)
+
+struct ThreadUtilsObject : public IThreadUtilsObject
+{
+  // nsISupports implementation
+  NS_DECL_ISUPPORTS
+
+  // IThreadUtilsObject implementation
+  NS_IMETHOD_(nsrefcnt) RefCnt() override { return mRefCnt; }
+  NS_IMETHOD_(int32_t) ID() override { return 0; }
+
+  int mCount; // Number of calls + arguments processed.
+  int mA0, mA1, mA2, mA3;
+  Spy mSpy; const Spy* mSpyPtr;
+  ThreadUtilsObject()
+    : mCount(0)
+    , mA0(0), mA1(0), mA2(0), mA3(0)
+    , mSpy(1), mSpyPtr(nullptr)
+  {}
+private:
+  virtual ~ThreadUtilsObject() = default;
+public:
+  void Test0() { mCount += 1; }
+  void Test1i(int a0) { mCount += 2; mA0 = a0; }
+  void Test2i(int a0, int a1) { mCount += 3; mA0 = a0; mA1 = a1; }
+  void Test3i(int a0, int a1, int a2)
+  {
+    mCount += 4; mA0 = a0; mA1 = a1; mA2 = a2;
+  }
+  void Test4i(int a0, int a1, int a2, int a3)
+  {
+    mCount += 5; mA0 = a0; mA1 = a1; mA2 = a2; mA3 = a3;
+  }
+  void Test1pi(int* ap)
+  {
+    mCount += 2; mA0 = ap ? *ap : -1;
+  }
+  void Test1pci(const int* ap)
+  {
+    mCount += 2; mA0 = ap ? *ap : -1;
+  }
+  void Test1ri(int& ar)
+  {
+    mCount += 2; mA0 = ar;
+  }
+  void Test1rri(int&& arr)
+  {
+    mCount += 2; mA0 = arr;
+  }
+  void Test1upi(mozilla::UniquePtr<int> aup)
+  {
+    mCount += 2; mA0 = aup ? *aup : -1;
+  }
+  void Test1rupi(mozilla::UniquePtr<int>& aup)
+  {
+    mCount += 2; mA0 = aup ? *aup : -1;
+  }
+  void Test1rrupi(mozilla::UniquePtr<int>&& aup)
+  {
+    mCount += 2; mA0 = aup ? *aup : -1;
+  }
+
+  void Test1s(Spy) { mCount += 2; }
+  void Test1ps(Spy*) { mCount += 2; }
+  void Test1rs(Spy&) { mCount += 2; }
+  void Test1rrs(Spy&&) { mCount += 2; }
+  void Test1ups(mozilla::UniquePtr<Spy>) { mCount += 2; }
+  void Test1rups(mozilla::UniquePtr<Spy>&) { mCount += 2; }
+  void Test1rrups(mozilla::UniquePtr<Spy>&&) { mCount += 2; }
+
+  // Possible parameter passing styles:
+  void TestByValue(Spy s)
+  {
+    if (gDebug) { printf("TestByValue(Spy[%d@%p])\n", s.mID, &s); }
+    mSpy = s;
+  };
+  void TestByConstLRef(const Spy& s)
+  {
+    if (gDebug) { printf("TestByConstLRef(Spy[%d@%p]&)\n", s.mID, &s); }
+    mSpy = s;
+  };
+  void TestByRRef(Spy&& s)
+  {
+    if (gDebug) { printf("TestByRRef(Spy[%d@%p]&&)\n", s.mID, &s); }
+    mSpy = mozilla::Move(s);
+  };
+  void TestByLRef(Spy& s)
+  {
+    if (gDebug) { printf("TestByLRef(Spy[%d@%p]&)\n", s.mID, &s); }
+    mSpy = s;
+    mSpyPtr = &s;
+  };
+  void TestByPointer(Spy* p)
+  {
+    if (p) {
+      if (gDebug) { printf("TestByPointer(&Spy[%d@%p])\n", p->mID, p); }
+      mSpy = *p;
+    } else {
+      if (gDebug) { printf("TestByPointer(nullptr)\n"); }
+    }
+    mSpyPtr = p;
+  };
+  void TestByPointerToConst(const Spy* p)
+  {
+    if (p) {
+      if (gDebug) { printf("TestByPointerToConst(&Spy[%d@%p])\n", p->mID, p); }
+      mSpy = *p;
+    } else {
+      if (gDebug) { printf("TestByPointerToConst(nullptr)\n"); }
+    }
+    mSpyPtr = p;
+  };
+};
+
+NS_IMPL_ISUPPORTS(ThreadUtilsObject, IThreadUtilsObject)
+
+class ThreadUtilsRefCountedFinal final
+{
+public:
+  ThreadUtilsRefCountedFinal() : m_refCount(0) {}
+  ~ThreadUtilsRefCountedFinal() {}
+  // 'AddRef' and 'Release' methods with different return types, to verify
+  // that the return type doesn't influence storage selection.
+  long AddRef(void) { return ++m_refCount; }
+  void Release(void) { --m_refCount; }
+private:
+  long m_refCount;
+};
+
+class ThreadUtilsRefCountedBase
+{
+public:
+  ThreadUtilsRefCountedBase() : m_refCount(0) {}
+  virtual ~ThreadUtilsRefCountedBase() {}
+  // 'AddRef' and 'Release' methods with different return types, to verify
+  // that the return type doesn't influence storage selection.
+  virtual void AddRef(void) { ++m_refCount; }
+  virtual MozExternalRefCountType Release(void) { return --m_refCount; }
+private:
+  MozExternalRefCountType m_refCount;
+};
+
+class ThreadUtilsRefCountedDerived
+  : public ThreadUtilsRefCountedBase
+{};
+
+class ThreadUtilsNonRefCounted
+{};
+
+} // namespace TestThreadUtils
+
+TEST(ThreadUtils, main)
+{
+#ifndef XPCOM_GLUE_AVOID_NSPR
+  using namespace TestThreadUtils;
+
+  static_assert(!IsParameterStorageClass<int>::value,
+                "'int' should not be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StoreCopyPassByValue<int>>::value,
+                "StoreCopyPassByValue<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StoreCopyPassByConstLRef<int>>::value,
+                "StoreCopyPassByConstLRef<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StoreCopyPassByLRef<int>>::value,
+                "StoreCopyPassByLRef<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StoreCopyPassByRRef<int>>::value,
+                "StoreCopyPassByRRef<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StoreRefPassByLRef<int>>::value,
+                "StoreRefPassByLRef<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StoreConstRefPassByConstLRef<int>>::value,
+                "StoreConstRefPassByConstLRef<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StorensRefPtrPassByPtr<int>>::value,
+                "StorensRefPtrPassByPtr<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StorePtrPassByPtr<int>>::value,
+                "StorePtrPassByPtr<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StoreConstPtrPassByConstPtr<int>>::value,
+                "StoreConstPtrPassByConstPtr<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StoreCopyPassByConstPtr<int>>::value,
+                "StoreCopyPassByConstPtr<int> should be recognized as Storage Class");
+  static_assert(IsParameterStorageClass<StoreCopyPassByPtr<int>>::value,
+                "StoreCopyPassByPtr<int> should be recognized as Storage Class");
+
+  RefPtr<ThreadUtilsObject> rpt(new ThreadUtilsObject);
+  int count = 0;
+
+  // Test legacy functions.
+
+  nsCOMPtr<nsIRunnable> r1 =
+    NewRunnableMethod(rpt, &ThreadUtilsObject::Test0);
+  r1->Run();
+  EXPECT_EQ(count += 1, rpt->mCount);
+
+  r1 = NewRunnableMethod<int>(rpt, &ThreadUtilsObject::Test1i, 11);
+  r1->Run();
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(11, rpt->mA0);
+
+  // Test variadic function with simple POD arguments.
+
+  r1 = NewRunnableMethod(rpt, &ThreadUtilsObject::Test0);
+  r1->Run();
+  EXPECT_EQ(count += 1, rpt->mCount);
+
+  static_assert(
+      mozilla::IsSame< ::detail::ParameterStorage<int>::Type,
+                      StoreCopyPassByValue<int>>::value,
+      "detail::ParameterStorage<int>::Type should be StoreCopyPassByValue<int>");
+  static_assert(
+      mozilla::IsSame< ::detail::ParameterStorage<StoreCopyPassByValue<int>>::Type,
+                      StoreCopyPassByValue<int>>::value,
+      "detail::ParameterStorage<StoreCopyPassByValue<int>>::Type should be StoreCopyPassByValue<int>");
+
+  r1 = NewRunnableMethod<int>(rpt, &ThreadUtilsObject::Test1i, 12);
+  r1->Run();
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(12, rpt->mA0);
+
+  r1 = NewRunnableMethod<int, int>(
+       rpt, &ThreadUtilsObject::Test2i, 21, 22);
+  r1->Run();
+  EXPECT_EQ(count += 3, rpt->mCount);
+  EXPECT_EQ(21, rpt->mA0);
+  EXPECT_EQ(22, rpt->mA1);
+
+  r1 = NewRunnableMethod<int, int, int>(
+       rpt, &ThreadUtilsObject::Test3i, 31, 32, 33);
+  r1->Run();
+  EXPECT_EQ(count += 4, rpt->mCount);
+  EXPECT_EQ(31, rpt->mA0);
+  EXPECT_EQ(32, rpt->mA1);
+  EXPECT_EQ(33, rpt->mA2);
+
+  r1 = NewRunnableMethod<int, int, int, int>(
+       rpt, &ThreadUtilsObject::Test4i, 41, 42, 43, 44);
+  r1->Run();
+  EXPECT_EQ(count += 5, rpt->mCount);
+  EXPECT_EQ(41, rpt->mA0);
+  EXPECT_EQ(42, rpt->mA1);
+  EXPECT_EQ(43, rpt->mA2);
+  EXPECT_EQ(44, rpt->mA3);
+
+  // More interesting types of arguments.
+
+  // Passing a short to make sure forwarding works with an inexact type match.
+  short int si = 11;
+  r1 = NewRunnableMethod<int>(rpt, &ThreadUtilsObject::Test1i, si);
+  r1->Run();
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(si, rpt->mA0);
+
+  // Raw pointer, possible cv-qualified.
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int*>::Type,
+                                StorePtrPassByPtr<int>>::value,
+                "detail::ParameterStorage<int*>::Type should be StorePtrPassByPtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int* const>::Type,
+                                StorePtrPassByPtr<int>>::value,
+                "detail::ParameterStorage<int* const>::Type should be StorePtrPassByPtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int* volatile>::Type,
+                                StorePtrPassByPtr<int>>::value,
+                "detail::ParameterStorage<int* volatile>::Type should be StorePtrPassByPtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int* const volatile>::Type,
+                                StorePtrPassByPtr<int>>::value,
+                "detail::ParameterStorage<int* const volatile>::Type should be StorePtrPassByPtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int*>::Type::stored_type,
+                                int*>::value,
+                "detail::ParameterStorage<int*>::Type::stored_type should be int*");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int*>::Type::passed_type,
+                                int*>::value,
+                "detail::ParameterStorage<int*>::Type::passed_type should be int*");
+  {
+    int i = 12;
+    r1 = NewRunnableMethod<int*>(rpt, &ThreadUtilsObject::Test1pi, &i);
+    r1->Run();
+    EXPECT_EQ(count += 2, rpt->mCount);
+    EXPECT_EQ(i, rpt->mA0);
+  }
+
+  // Raw pointer to const.
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<const int*>::Type,
+                                StoreConstPtrPassByConstPtr<int>>::value,
+                "detail::ParameterStorage<const int*>::Type should be StoreConstPtrPassByConstPtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<const int* const>::Type,
+                                StoreConstPtrPassByConstPtr<int>>::value,
+                "detail::ParameterStorage<const int* const>::Type should be StoreConstPtrPassByConstPtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<const int* volatile>::Type,
+                                StoreConstPtrPassByConstPtr<int>>::value,
+                "detail::ParameterStorage<const int* volatile>::Type should be StoreConstPtrPassByConstPtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<const int* const volatile>::Type,
+                                StoreConstPtrPassByConstPtr<int>>::value,
+                "detail::ParameterStorage<const int* const volatile>::Type should be StoreConstPtrPassByConstPtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<const int*>::Type::stored_type,
+                                const int*>::value,
+                "detail::ParameterStorage<const int*>::Type::stored_type should be const int*");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<const int*>::Type::passed_type,
+                                const int*>::value,
+                "detail::ParameterStorage<const int*>::Type::passed_type should be const int*");
+  {
+    int i = 1201;
+    r1 = NewRunnableMethod<const int*>(rpt, &ThreadUtilsObject::Test1pci, &i);
+    r1->Run();
+    EXPECT_EQ(count += 2, rpt->mCount);
+    EXPECT_EQ(i, rpt->mA0);
+  }
+
+  // Raw pointer to copy.
+  static_assert(mozilla::IsSame<StoreCopyPassByPtr<int>::stored_type,
+                                int>::value,
+                "StoreCopyPassByPtr<int>::stored_type should be int");
+  static_assert(mozilla::IsSame<StoreCopyPassByPtr<int>::passed_type,
+                                int*>::value,
+                "StoreCopyPassByPtr<int>::passed_type should be int*");
+  {
+    int i = 1202;
+    r1 = NewRunnableMethod<StoreCopyPassByPtr<int>>(
+         rpt, &ThreadUtilsObject::Test1pi, i);
+    r1->Run();
+    EXPECT_EQ(count += 2, rpt->mCount);
+    EXPECT_EQ(i, rpt->mA0);
+  }
+
+  // Raw pointer to const copy.
+  static_assert(mozilla::IsSame<StoreCopyPassByConstPtr<int>::stored_type,
+                                int>::value,
+                "StoreCopyPassByConstPtr<int>::stored_type should be int");
+  static_assert(mozilla::IsSame<StoreCopyPassByConstPtr<int>::passed_type,
+                                const int*>::value,
+                "StoreCopyPassByConstPtr<int>::passed_type should be const int*");
+  {
+    int i = 1203;
+    r1 = NewRunnableMethod<StoreCopyPassByConstPtr<int>>(
+         rpt, &ThreadUtilsObject::Test1pci, i);
+    r1->Run();
+    EXPECT_EQ(count += 2, rpt->mCount);
+    EXPECT_EQ(i, rpt->mA0);
+  }
+
+  // nsRefPtr to pointer.
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<StorensRefPtrPassByPtr<SpyWithISupports>>::Type,
+                                StorensRefPtrPassByPtr<SpyWithISupports>>::value,
+                "ParameterStorage<StorensRefPtrPassByPtr<SpyWithISupports>>::Type should be StorensRefPtrPassByPtr<SpyWithISupports>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<SpyWithISupports*>::Type,
+                                StorensRefPtrPassByPtr<SpyWithISupports>>::value,
+                "ParameterStorage<SpyWithISupports*>::Type should be StorensRefPtrPassByPtr<SpyWithISupports>");
+  static_assert(mozilla::IsSame<StorensRefPtrPassByPtr<SpyWithISupports>::stored_type,
+                                RefPtr<SpyWithISupports>>::value,
+                "StorensRefPtrPassByPtr<SpyWithISupports>::stored_type should be RefPtr<SpyWithISupports>");
+  static_assert(mozilla::IsSame<StorensRefPtrPassByPtr<SpyWithISupports>::passed_type,
+                                SpyWithISupports*>::value,
+                "StorensRefPtrPassByPtr<SpyWithISupports>::passed_type should be SpyWithISupports*");
+  // (more nsRefPtr tests below)
+
+  // nsRefPtr for ref-countable classes that do not derive from ISupports.
+  static_assert(::detail::HasRefCountMethods<ThreadUtilsRefCountedFinal>::value,
+                "ThreadUtilsRefCountedFinal has AddRef() and Release()");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<ThreadUtilsRefCountedFinal*>::Type,
+                                StorensRefPtrPassByPtr<ThreadUtilsRefCountedFinal>>::value,
+                "ParameterStorage<ThreadUtilsRefCountedFinal*>::Type should be StorensRefPtrPassByPtr<ThreadUtilsRefCountedFinal>");
+  static_assert(::detail::HasRefCountMethods<ThreadUtilsRefCountedBase>::value,
+                "ThreadUtilsRefCountedBase has AddRef() and Release()");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<ThreadUtilsRefCountedBase*>::Type,
+                                StorensRefPtrPassByPtr<ThreadUtilsRefCountedBase>>::value,
+                "ParameterStorage<ThreadUtilsRefCountedBase*>::Type should be StorensRefPtrPassByPtr<ThreadUtilsRefCountedBase>");
+  static_assert(::detail::HasRefCountMethods<ThreadUtilsRefCountedDerived>::value,
+                "ThreadUtilsRefCountedDerived has AddRef() and Release()");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<ThreadUtilsRefCountedDerived*>::Type,
+                                StorensRefPtrPassByPtr<ThreadUtilsRefCountedDerived>>::value,
+                "ParameterStorage<ThreadUtilsRefCountedDerived*>::Type should be StorensRefPtrPassByPtr<ThreadUtilsRefCountedDerived>");
+
+  static_assert(!::detail::HasRefCountMethods<ThreadUtilsNonRefCounted>::value,
+                "ThreadUtilsNonRefCounted doesn't have AddRef() and Release()");
+  static_assert(!mozilla::IsSame< ::detail::ParameterStorage<ThreadUtilsNonRefCounted*>::Type,
+                                 StorensRefPtrPassByPtr<ThreadUtilsNonRefCounted>>::value,
+                "ParameterStorage<ThreadUtilsNonRefCounted*>::Type should NOT be StorensRefPtrPassByPtr<ThreadUtilsNonRefCounted>");
+
+  // Lvalue reference.
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int&>::Type,
+                                StoreRefPassByLRef<int>>::value,
+                "ParameterStorage<int&>::Type should be StoreRefPassByLRef<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int&>::Type::stored_type,
+                                StoreRefPassByLRef<int>::stored_type>::value,
+                "ParameterStorage<int&>::Type::stored_type should be StoreRefPassByLRef<int>::stored_type");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int&>::Type::stored_type,
+                                int&>::value,
+                "ParameterStorage<int&>::Type::stored_type should be int&");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int&>::Type::passed_type,
+                                int&>::value,
+                "ParameterStorage<int&>::Type::passed_type should be int&");
+  {
+    int i = 13;
+    r1 = NewRunnableMethod<int&>(rpt, &ThreadUtilsObject::Test1ri, i);
+    r1->Run();
+    EXPECT_EQ(count += 2, rpt->mCount);
+    EXPECT_EQ(i, rpt->mA0);
+  }
+
+  // Rvalue reference -- Actually storing a copy and then moving it.
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int&&>::Type,
+                                StoreCopyPassByRRef<int>>::value,
+                "ParameterStorage<int&&>::Type should be StoreCopyPassByRRef<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int&&>::Type::stored_type,
+                                StoreCopyPassByRRef<int>::stored_type>::value,
+                "ParameterStorage<int&&>::Type::stored_type should be StoreCopyPassByRRef<int>::stored_type");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int&&>::Type::stored_type,
+                                int>::value,
+                "ParameterStorage<int&&>::Type::stored_type should be int");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<int&&>::Type::passed_type,
+                                int&&>::value,
+                "ParameterStorage<int&&>::Type::passed_type should be int&&");
+  {
+    int i = 14;
+    r1 = NewRunnableMethod<int&&>(
+          rpt, &ThreadUtilsObject::Test1rri, mozilla::Move(i));
+  }
+  r1->Run();
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(14, rpt->mA0);
+
+  // Null unique pointer, by semi-implicit store&move with "T&&" syntax.
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<mozilla::UniquePtr<int>&&>::Type,
+                                StoreCopyPassByRRef<mozilla::UniquePtr<int>>>::value,
+                "ParameterStorage<UniquePtr<int>&&>::Type should be StoreCopyPassByRRef<UniquePtr<int>>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<mozilla::UniquePtr<int>&&>::Type::stored_type,
+                                StoreCopyPassByRRef<mozilla::UniquePtr<int>>::stored_type>::value,
+                "ParameterStorage<UniquePtr<int>&&>::Type::stored_type should be StoreCopyPassByRRef<UniquePtr<int>>::stored_type");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<mozilla::UniquePtr<int>&&>::Type::stored_type,
+                                mozilla::UniquePtr<int>>::value,
+                "ParameterStorage<UniquePtr<int>&&>::Type::stored_type should be UniquePtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<mozilla::UniquePtr<int>&&>::Type::passed_type,
+                                mozilla::UniquePtr<int>&&>::value,
+                "ParameterStorage<UniquePtr<int>&&>::Type::passed_type should be UniquePtr<int>&&");
+  {
+    mozilla::UniquePtr<int> upi;
+    r1 = NewRunnableMethod<mozilla::UniquePtr<int>&&>(
+          rpt, &ThreadUtilsObject::Test1upi, mozilla::Move(upi));
+  }
+  r1->Run();
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(-1, rpt->mA0);
+  rpt->mA0 = 0;
+
+  // Null unique pointer, by explicit store&move with "StoreCopyPassByRRef<T>" syntax.
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<StoreCopyPassByRRef<mozilla::UniquePtr<int>>>::Type::stored_type,
+                                StoreCopyPassByRRef<mozilla::UniquePtr<int>>::stored_type>::value,
+                "ParameterStorage<StoreCopyPassByRRef<UniquePtr<int>>>::Type::stored_type should be StoreCopyPassByRRef<UniquePtr<int>>::stored_type");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<StoreCopyPassByRRef<mozilla::UniquePtr<int>>>::Type::stored_type,
+                                StoreCopyPassByRRef<mozilla::UniquePtr<int>>::stored_type>::value,
+                "ParameterStorage<StoreCopyPassByRRef<UniquePtr<int>>>::Type::stored_type should be StoreCopyPassByRRef<UniquePtr<int>>::stored_type");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<StoreCopyPassByRRef<mozilla::UniquePtr<int>>>::Type::stored_type,
+                                mozilla::UniquePtr<int>>::value,
+                "ParameterStorage<StoreCopyPassByRRef<UniquePtr<int>>>::Type::stored_type should be UniquePtr<int>");
+  static_assert(mozilla::IsSame< ::detail::ParameterStorage<StoreCopyPassByRRef<mozilla::UniquePtr<int>>>::Type::passed_type,
+                                mozilla::UniquePtr<int>&&>::value,
+                "ParameterStorage<StoreCopyPassByRRef<UniquePtr<int>>>::Type::passed_type should be UniquePtr<int>&&");
+  {
+    mozilla::UniquePtr<int> upi;
+    r1 = NewRunnableMethod
+         <StoreCopyPassByRRef<mozilla::UniquePtr<int>>>(
+           rpt, &ThreadUtilsObject::Test1upi, mozilla::Move(upi));
+  }
+  r1->Run();
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(-1, rpt->mA0);
+
+  // Unique pointer as xvalue.
+  {
+    mozilla::UniquePtr<int> upi = mozilla::MakeUnique<int>(1);
+    r1 = NewRunnableMethod<mozilla::UniquePtr<int>&&>(
+           rpt, &ThreadUtilsObject::Test1upi, mozilla::Move(upi));
+  }
+  r1->Run();
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(1, rpt->mA0);
+
+  {
+    mozilla::UniquePtr<int> upi = mozilla::MakeUnique<int>(1);
+    r1 = NewRunnableMethod
+         <StoreCopyPassByRRef<mozilla::UniquePtr<int>>>
+         (rpt, &ThreadUtilsObject::Test1upi, mozilla::Move(upi));
+  }
+  r1->Run();
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(1, rpt->mA0);
+
+  // Unique pointer as prvalue.
+  r1 = NewRunnableMethod<mozilla::UniquePtr<int>&&>(
+         rpt, &ThreadUtilsObject::Test1upi, mozilla::MakeUnique<int>(2));
+  r1->Run();
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(2, rpt->mA0);
+
+  // Unique pointer as lvalue to lref.
+  {
+    mozilla::UniquePtr<int> upi;
+    r1 = NewRunnableMethod<mozilla::UniquePtr<int>&>(
+           rpt, &ThreadUtilsObject::Test1rupi, upi);
+    // Passed as lref, so Run() must be called while local upi is still alive!
+    r1->Run();
+  }
+  EXPECT_EQ(count += 2, rpt->mCount);
+  EXPECT_EQ(-1, rpt->mA0);
+
+  // Verify copy/move assumptions.
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store copy from lvalue, pass by value\n", __LINE__); }
+  { // Block around nsCOMPtr lifetime.
+    nsCOMPtr<nsIRunnable> r2;
+    { // Block around Spy lifetime.
+      if (gDebug) { printf("%d - Spy s(10)\n", __LINE__); }
+      Spy s(10);
+      EXPECT_EQ(1, gConstructions);
+      EXPECT_EQ(1, gAlive);
+      if (gDebug) { printf("%d - r2 = NewRunnableMethod<StoreCopyPassByValue<Spy>>(&TestByValue, s)\n", __LINE__); }
+      r2 = NewRunnableMethod<StoreCopyPassByValue<Spy>>(
+           rpt, &ThreadUtilsObject::TestByValue, s);
+      EXPECT_EQ(2, gAlive);
+      EXPECT_LE(1, gCopyConstructions); // At least 1 copy-construction.
+      Spy::ClearActions();
+      if (gDebug) { printf("%d - End block with Spy s(10)\n", __LINE__); }
+    }
+    EXPECT_EQ(1, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r2->Run();
+    EXPECT_LE(1, gCopyConstructions); // Another copy-construction in call.
+    EXPECT_EQ(10, rpt->mSpy.mID);
+    EXPECT_LE(1, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store copy from prvalue, pass by value\n", __LINE__); }
+  {
+    if (gDebug) { printf("%d - r3 = NewRunnableMethod<StoreCopyPassByValue<Spy>>(&TestByValue, Spy(11))\n", __LINE__); }
+    nsCOMPtr<nsIRunnable> r3 =
+      NewRunnableMethod<StoreCopyPassByValue<Spy>>(
+        rpt, &ThreadUtilsObject::TestByValue, Spy(11));
+    EXPECT_EQ(1, gAlive);
+    EXPECT_EQ(1, gConstructions);
+    EXPECT_LE(1, gMoveConstructions);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r3->Run();
+    EXPECT_LE(1, gCopyConstructions); // Another copy-construction in call.
+    EXPECT_EQ(11, rpt->mSpy.mID);
+    EXPECT_LE(1, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+
+  Spy::ClearAll();
+  { // Store copy from xvalue, pass by value.
+    nsCOMPtr<nsIRunnable> r4;
+    {
+      Spy s(12);
+      EXPECT_EQ(1, gConstructions);
+      EXPECT_EQ(1, gAlive);
+      Spy::ClearActions();
+      r4 = NewRunnableMethod<StoreCopyPassByValue<Spy>>(
+          rpt, &ThreadUtilsObject::TestByValue, mozilla::Move(s));
+      EXPECT_LE(1, gMoveConstructions);
+      EXPECT_EQ(1, gAlive);
+      EXPECT_EQ(1, gZombies);
+      Spy::ClearActions();
+    }
+    EXPECT_EQ(1, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    EXPECT_EQ(0, gZombies);
+    Spy::ClearActions();
+    r4->Run();
+    EXPECT_LE(1, gCopyConstructions); // Another copy-construction in call.
+    EXPECT_EQ(12, rpt->mSpy.mID);
+    EXPECT_LE(1, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+  }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+  // Won't test xvalues anymore, prvalues are enough to verify all rvalues.
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store copy from lvalue, pass by const lvalue ref\n", __LINE__); }
+  { // Block around nsCOMPtr lifetime.
+    nsCOMPtr<nsIRunnable> r5;
+    { // Block around Spy lifetime.
+      if (gDebug) { printf("%d - Spy s(20)\n", __LINE__); }
+      Spy s(20);
+      EXPECT_EQ(1, gConstructions);
+      EXPECT_EQ(1, gAlive);
+      if (gDebug) { printf("%d - r5 = NewRunnableMethod<StoreCopyPassByConstLRef<Spy>>(&TestByConstLRef, s)\n", __LINE__); }
+      r5 = NewRunnableMethod<StoreCopyPassByConstLRef<Spy>>(
+           rpt, &ThreadUtilsObject::TestByConstLRef, s);
+      EXPECT_EQ(2, gAlive);
+      EXPECT_LE(1, gCopyConstructions); // At least 1 copy-construction.
+      Spy::ClearActions();
+      if (gDebug) { printf("%d - End block with Spy s(20)\n", __LINE__); }
+    }
+    EXPECT_EQ(1, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r5->Run();
+    EXPECT_EQ(0, gCopyConstructions); // No copies in call.
+    EXPECT_EQ(20, rpt->mSpy.mID);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store copy from prvalue, pass by const lvalue ref\n", __LINE__); }
+  {
+    if (gDebug) { printf("%d - r6 = NewRunnableMethod<StoreCopyPassByConstLRef<Spy>>(&TestByConstLRef, Spy(21))\n", __LINE__); }
+    nsCOMPtr<nsIRunnable> r6 =
+      NewRunnableMethod<StoreCopyPassByConstLRef<Spy>>(
+        rpt, &ThreadUtilsObject::TestByConstLRef, Spy(21));
+    EXPECT_EQ(1, gAlive);
+    EXPECT_EQ(1, gConstructions);
+    EXPECT_LE(1, gMoveConstructions);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r6->Run();
+    EXPECT_EQ(0, gCopyConstructions); // No copies in call.
+    EXPECT_EQ(21, rpt->mSpy.mID);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store copy from lvalue, pass by rvalue ref\n", __LINE__); }
+  { // Block around nsCOMPtr lifetime.
+    nsCOMPtr<nsIRunnable> r7;
+    { // Block around Spy lifetime.
+      if (gDebug) { printf("%d - Spy s(30)\n", __LINE__); }
+      Spy s(30);
+      EXPECT_EQ(1, gConstructions);
+      EXPECT_EQ(1, gAlive);
+      if (gDebug) { printf("%d - r7 = NewRunnableMethod<StoreCopyPassByRRef<Spy>>(&TestByRRef, s)\n", __LINE__); }
+      r7 = NewRunnableMethod<StoreCopyPassByRRef<Spy>>(
+           rpt, &ThreadUtilsObject::TestByRRef, s);
+      EXPECT_EQ(2, gAlive);
+      EXPECT_LE(1, gCopyConstructions); // At least 1 copy-construction.
+      Spy::ClearActions();
+      if (gDebug) { printf("%d - End block with Spy s(30)\n", __LINE__); }
+    }
+    EXPECT_EQ(1, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r7->Run();
+    EXPECT_LE(1, gMoves); // Move in call.
+    EXPECT_EQ(30, rpt->mSpy.mID);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(0, gAlive); // Spy inside Test is not counted.
+    EXPECT_EQ(1, gZombies); // Our local spy should now be a zombie.
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store copy from prvalue, pass by rvalue ref\n", __LINE__); }
+  {
+    if (gDebug) { printf("%d - r8 = NewRunnableMethod<StoreCopyPassByRRef<Spy>>(&TestByRRef, Spy(31))\n", __LINE__); }
+    nsCOMPtr<nsIRunnable> r8 =
+      NewRunnableMethod<StoreCopyPassByRRef<Spy>>(
+        rpt, &ThreadUtilsObject::TestByRRef, Spy(31));
+    EXPECT_EQ(1, gAlive);
+    EXPECT_EQ(1, gConstructions);
+    EXPECT_LE(1, gMoveConstructions);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r8->Run();
+    EXPECT_LE(1, gMoves); // Move in call.
+    EXPECT_EQ(31, rpt->mSpy.mID);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(0, gAlive); // Spy inside Test is not counted.
+    EXPECT_EQ(1, gZombies); // Our local spy should now be a zombie.
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store lvalue ref, pass lvalue ref\n", __LINE__); }
+  {
+    if (gDebug) { printf("%d - Spy s(40)\n", __LINE__); }
+    Spy s(40);
+    EXPECT_EQ(1, gConstructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - r9 = NewRunnableMethod<Spy&>(&TestByLRef, s)\n", __LINE__); }
+    nsCOMPtr<nsIRunnable> r9 =
+      NewRunnableMethod<Spy&>(
+        rpt, &ThreadUtilsObject::TestByLRef, s);
+    EXPECT_EQ(0, gAllConstructions);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r9->Run();
+    EXPECT_LE(1, gAssignments); // Assignment from reference in call.
+    EXPECT_EQ(40, rpt->mSpy.mID);
+    EXPECT_EQ(&s, rpt->mSpyPtr);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive); // Spy inside Test is not counted.
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store nsRefPtr, pass by pointer\n", __LINE__); }
+  { // Block around nsCOMPtr lifetime.
+    nsCOMPtr<nsIRunnable> r10;
+    SpyWithISupports* ptr = 0;
+    { // Block around RefPtr<Spy> lifetime.
+      if (gDebug) { printf("%d - RefPtr<SpyWithISupports> s(new SpyWithISupports(45))\n", __LINE__); }
+      RefPtr<SpyWithISupports> s(new SpyWithISupports(45));
+      ptr = s.get();
+      EXPECT_EQ(1, gConstructions);
+      EXPECT_EQ(1, gAlive);
+      if (gDebug) { printf("%d - r10 = NewRunnableMethod<StorensRefPtrPassByPtr<Spy>>(&TestByRRef, s.get())\n", __LINE__); }
+      r10 = NewRunnableMethod<StorensRefPtrPassByPtr<SpyWithISupports>>(
+            rpt, &ThreadUtilsObject::TestByPointer, s.get());
+      EXPECT_LE(0, gAllConstructions);
+      EXPECT_EQ(1, gAlive);
+      Spy::ClearActions();
+      if (gDebug) { printf("%d - End block with RefPtr<Spy> s\n", __LINE__); }
+    }
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r10->Run();
+    EXPECT_LE(1, gAssignments); // Assignment from pointee in call.
+    EXPECT_EQ(45, rpt->mSpy.mID);
+    EXPECT_EQ(ptr, rpt->mSpyPtr);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive); // Spy inside Test is not counted.
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store pointer to lvalue, pass by pointer\n", __LINE__); }
+  {
+    if (gDebug) { printf("%d - Spy s(55)\n", __LINE__); }
+    Spy s(55);
+    EXPECT_EQ(1, gConstructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - r11 = NewRunnableMethod<Spy*>(&TestByPointer, s)\n", __LINE__); }
+    nsCOMPtr<nsIRunnable> r11 =
+      NewRunnableMethod<Spy*>(
+        rpt, &ThreadUtilsObject::TestByPointer, &s);
+    EXPECT_EQ(0, gAllConstructions);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r11->Run();
+    EXPECT_LE(1, gAssignments); // Assignment from pointee in call.
+    EXPECT_EQ(55, rpt->mSpy.mID);
+    EXPECT_EQ(&s, rpt->mSpyPtr);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive); // Spy inside Test is not counted.
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+
+  Spy::ClearAll();
+  if (gDebug) { printf("%d - Test: Store pointer to const lvalue, pass by pointer\n", __LINE__); }
+  {
+    if (gDebug) { printf("%d - Spy s(60)\n", __LINE__); }
+    Spy s(60);
+    EXPECT_EQ(1, gConstructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - r12 = NewRunnableMethod<Spy*>(&TestByPointer, s)\n", __LINE__); }
+    nsCOMPtr<nsIRunnable> r12 =
+      NewRunnableMethod<const Spy*>(
+        rpt, &ThreadUtilsObject::TestByPointerToConst, &s);
+    EXPECT_EQ(0, gAllConstructions);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive);
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - Run()\n", __LINE__); }
+    r12->Run();
+    EXPECT_LE(1, gAssignments); // Assignment from pointee in call.
+    EXPECT_EQ(60, rpt->mSpy.mID);
+    EXPECT_EQ(&s, rpt->mSpyPtr);
+    EXPECT_EQ(0, gDestructions);
+    EXPECT_EQ(1, gAlive); // Spy inside Test is not counted.
+    Spy::ClearActions();
+    if (gDebug) { printf("%d - End block with r\n", __LINE__); }
+  }
+  if (gDebug) { printf("%d - After end block with r\n", __LINE__); }
+  EXPECT_EQ(1, gDestructions);
+  EXPECT_EQ(0, gAlive);
+#endif // XPCOM_GLUE_AVOID_NSPR
+}
diff --git a/xpcom/glue/tests/gtest/moz.build b/xpcom/glue/tests/gtest/moz.build
new file mode 100644
index 000000000..9f4d83a3e
--- /dev/null
+++ b/xpcom/glue/tests/gtest/moz.build
@@ -0,0 +1,22 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+UNIFIED_SOURCES += [
+    'TestArray.cpp',
+    'TestFileUtils.cpp',
+    'TestGCPostBarriers.cpp',
+    'TestNsDeque.cpp',
+    'TestThreadUtils.cpp',
+]
+
+LOCAL_INCLUDES = [
+    '../..',
+]
+
+FINAL_LIBRARY = 'xul-gtest'
+
+if CONFIG['GNU_CXX']:
+    CXXFLAGS += ['-Wno-error=shadow']
diff --git a/xpcom/idl-parser/setup.py b/xpcom/idl-parser/setup.py
new file mode 100644
index 000000000..f42edbb99
--- /dev/null
+++ b/xpcom/idl-parser/setup.py
@@ -0,0 +1,15 @@
+from setuptools import setup, find_packages
+
+
+setup(
+    name='xpidl',
+    version='1.0',
+    description='Parser and header generator for xpidl files.',
+    author='Mozilla Foundation',
+    license='MPL 2.0',
+    packages=find_packages(),
+    install_requires=['ply>=3.6,<4.0'],
+    url='https://github.com/pelmers/xpidl',
+    entry_points={'console_scripts': ['header.py = xpidl.header:main']},
+    keywords=['xpidl', 'parser']
+)
diff --git a/xpcom/idl-parser/xpidl/__init__.py b/xpcom/idl-parser/xpidl/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/xpcom/idl-parser/xpidl/__init__.py
diff --git a/xpcom/idl-parser/xpidl/header.py b/xpcom/idl-parser/xpidl/header.py
new file mode 100644
index 000000000..8e02a7d11
--- /dev/null
+++ b/xpcom/idl-parser/xpidl/header.py
@@ -0,0 +1,566 @@
+#!/usr/bin/env python
+# header.py - Generate C++ header files from IDL.
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+"""Print a C++ header file for the IDL files specified on the command line"""
+
+import sys
+import os.path
+import re
+import xpidl
+import itertools
+import glob
+
+printdoccomments = False
+
+if printdoccomments:
+    def printComments(fd, clist, indent):
+        for c in clist:
+            fd.write("%s%s\n" % (indent, c))
+else:
+    def printComments(fd, clist, indent):
+        pass
+
+
+def firstCap(str):
+    return str[0].upper() + str[1:]
+
+
+def attributeParamName(a):
+    return "a" + firstCap(a.name)
+
+
+def attributeParamNames(a):
+    l = [attributeParamName(a)]
+    if a.implicit_jscontext:
+        l.insert(0, "cx")
+    return ", ".join(l)
+
+
+def attributeNativeName(a, getter):
+    binaryname = a.binaryname is not None and a.binaryname or firstCap(a.name)
+    return "%s%s" % (getter and 'Get' or 'Set', binaryname)
+
+
+def attributeReturnType(a, macro):
+    """macro should be NS_IMETHOD or NS_IMETHODIMP"""
+    if a.nostdcall:
+        ret = macro == "NS_IMETHOD" and "virtual nsresult" or "nsresult"
+    else:
+        ret = macro
+    if a.must_use:
+        ret = "MOZ_MUST_USE " + ret
+    return ret
+
+
+def attributeParamlist(a, getter):
+    l = ["%s%s" % (a.realtype.nativeType(getter and 'out' or 'in'),
+                   attributeParamName(a))]
+    if a.implicit_jscontext:
+        l.insert(0, "JSContext* cx")
+
+    return ", ".join(l)
+
+
+def attributeAsNative(a, getter, declType = 'NS_IMETHOD'):
+        deprecated = a.deprecated and "NS_DEPRECATED " or ""
+        params = {'deprecated': deprecated,
+                  'returntype': attributeReturnType(a, declType),
+                  'binaryname': attributeNativeName(a, getter),
+                  'paramlist': attributeParamlist(a, getter)}
+        return "%(deprecated)s%(returntype)s %(binaryname)s(%(paramlist)s)" % params
+
+
+def methodNativeName(m):
+    return m.binaryname is not None and m.binaryname or firstCap(m.name)
+
+
+def methodReturnType(m, macro):
+    """macro should be NS_IMETHOD or NS_IMETHODIMP"""
+    if m.nostdcall and m.notxpcom:
+        ret = "%s%s" % (macro == "NS_IMETHOD" and "virtual " or "",
+                        m.realtype.nativeType('in').strip())
+    elif m.nostdcall:
+        ret = "%snsresult" % (macro == "NS_IMETHOD" and "virtual " or "")
+    elif m.notxpcom:
+        ret = "%s_(%s)" % (macro, m.realtype.nativeType('in').strip())
+    else:
+        ret = macro
+    if m.must_use:
+        ret = "MOZ_MUST_USE " + ret
+    return ret
+
+
+def methodAsNative(m, declType = 'NS_IMETHOD'):
+    return "%s %s(%s)" % (methodReturnType(m, declType),
+                          methodNativeName(m),
+                          paramlistAsNative(m))
+
+
+def paramlistAsNative(m, empty='void'):
+    l = [paramAsNative(p) for p in m.params]
+
+    if m.implicit_jscontext:
+        l.append("JSContext* cx")
+
+    if m.optional_argc:
+        l.append('uint8_t _argc')
+
+    if not m.notxpcom and m.realtype.name != 'void':
+        l.append(paramAsNative(xpidl.Param(paramtype='out',
+                                           type=None,
+                                           name='_retval',
+                                           attlist=[],
+                                           location=None,
+                                           realtype=m.realtype)))
+
+    # Set any optional out params to default to nullptr. Skip if we just added
+    # extra non-optional args to l.
+    if len(l) == len(m.params):
+        paramIter = len(m.params) - 1
+        while (paramIter >= 0 and m.params[paramIter].optional and
+                m.params[paramIter].paramtype == "out"):
+            t = m.params[paramIter].type
+            # Strings can't be optional, so this shouldn't happen, but let's make sure:
+            if t == "AString" or t == "ACString" or t == "DOMString" or t == "AUTF8String":
+                break
+            l[paramIter] += " = nullptr"
+            paramIter -= 1
+
+    if len(l) == 0:
+        return empty
+
+    return ", ".join(l)
+
+
+def paramAsNative(p):
+    return "%s%s" % (p.nativeType(),
+                     p.name)
+
+
+def paramlistNames(m):
+    names = [p.name for p in m.params]
+
+    if m.implicit_jscontext:
+        names.append('cx')
+
+    if m.optional_argc:
+        names.append('_argc')
+
+    if not m.notxpcom and m.realtype.name != 'void':
+        names.append('_retval')
+
+    if len(names) == 0:
+        return ''
+    return ', '.join(names)
+
+header = """/*
+ * DO NOT EDIT.  THIS FILE IS GENERATED FROM %(filename)s
+ */
+
+#ifndef __gen_%(basename)s_h__
+#define __gen_%(basename)s_h__
+"""
+
+include = """
+#ifndef __gen_%(basename)s_h__
+#include "%(basename)s.h"
+#endif
+"""
+
+jsvalue_include = """
+#include "js/Value.h"
+"""
+
+infallible_includes = """
+#include "mozilla/Assertions.h"
+#include "mozilla/DebugOnly.h"
+"""
+
+header_end = """/* For IDL files that don't want to include root IDL files. */
+#ifndef NS_NO_VTABLE
+#define NS_NO_VTABLE
+#endif
+"""
+
+footer = """
+#endif /* __gen_%(basename)s_h__ */
+"""
+
+forward_decl = """class %(name)s; /* forward declaration */
+
+"""
+
+
+def idl_basename(f):
+    """returns the base name of a file with the last extension stripped"""
+    return os.path.basename(f).rpartition('.')[0]
+
+
+def print_header(idl, fd, filename):
+    fd.write(header % {'filename': filename,
+                       'basename': idl_basename(filename)})
+
+    foundinc = False
+    for inc in idl.includes():
+        if not foundinc:
+            foundinc = True
+            fd.write('\n')
+        fd.write(include % {'basename': idl_basename(inc.filename)})
+
+    if idl.needsJSTypes():
+        fd.write(jsvalue_include)
+
+    # Include some extra files if any attributes are infallible.
+    for iface in [p for p in idl.productions if p.kind == 'interface']:
+        for attr in [m for m in iface.members if isinstance(m, xpidl.Attribute)]:
+            if attr.infallible:
+                fd.write(infallible_includes)
+                break
+
+    fd.write('\n')
+    fd.write(header_end)
+
+    for p in idl.productions:
+        if p.kind == 'include':
+            continue
+        if p.kind == 'cdata':
+            fd.write(p.data)
+            continue
+
+        if p.kind == 'forward':
+            fd.write(forward_decl % {'name': p.name})
+            continue
+        if p.kind == 'interface':
+            write_interface(p, fd)
+            continue
+        if p.kind == 'typedef':
+            printComments(fd, p.doccomments, '')
+            fd.write("typedef %s %s;\n\n" % (p.realtype.nativeType('in'),
+                                             p.name))
+
+    fd.write(footer % {'basename': idl_basename(filename)})
+
+iface_header = r"""
+/* starting interface:    %(name)s */
+#define %(defname)s_IID_STR "%(iid)s"
+
+#define %(defname)s_IID \
+  {0x%(m0)s, 0x%(m1)s, 0x%(m2)s, \
+    { %(m3joined)s }}
+
+"""
+
+uuid_decoder = re.compile(r"""(?P<m0>[a-f0-9]{8})-
+                              (?P<m1>[a-f0-9]{4})-
+                              (?P<m2>[a-f0-9]{4})-
+                              (?P<m3>[a-f0-9]{4})-
+                              (?P<m4>[a-f0-9]{12})$""", re.X)
+
+iface_prolog = """ {
+ public:
+
+  NS_DECLARE_STATIC_IID_ACCESSOR(%(defname)s_IID)
+
+"""
+
+iface_epilog = """};
+
+  NS_DEFINE_STATIC_IID_ACCESSOR(%(name)s, %(defname)s_IID)
+
+/* Use this macro when declaring classes that implement this interface. */
+#define NS_DECL_%(macroname)s """
+
+iface_nonvirtual = """
+
+/* Use this macro when declaring the members of this interface when the
+   class doesn't implement the interface. This is useful for forwarding. */
+#define NS_DECL_NON_VIRTUAL_%(macroname)s """
+
+iface_forward = """
+
+/* Use this macro to declare functions that forward the behavior of this interface to another object. */
+#define NS_FORWARD_%(macroname)s(_to) """
+
+iface_forward_safe = """
+
+/* Use this macro to declare functions that forward the behavior of this interface to another object in a safe way. */
+#define NS_FORWARD_SAFE_%(macroname)s(_to) """
+
+iface_template_prolog = """
+
+#if 0
+/* Use the code below as a template for the implementation class for this interface. */
+
+/* Header file */
+class %(implclass)s : public %(name)s
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_%(macroname)s
+
+  %(implclass)s();
+
+private:
+  ~%(implclass)s();
+
+protected:
+  /* additional members */
+};
+
+/* Implementation file */
+NS_IMPL_ISUPPORTS(%(implclass)s, %(name)s)
+
+%(implclass)s::%(implclass)s()
+{
+  /* member initializers and constructor code */
+}
+
+%(implclass)s::~%(implclass)s()
+{
+  /* destructor code */
+}
+
+"""
+
+example_tmpl = """%(returntype)s %(implclass)s::%(nativeName)s(%(paramList)s)
+{
+    return NS_ERROR_NOT_IMPLEMENTED;
+}
+"""
+
+iface_template_epilog = """/* End of implementation class template. */
+#endif
+
+"""
+
+attr_infallible_tmpl = """\
+  inline %(realtype)s%(nativename)s(%(args)s)
+  {
+    %(realtype)sresult;
+    mozilla::DebugOnly<nsresult> rv = %(nativename)s(%(argnames)s&result);
+    MOZ_ASSERT(NS_SUCCEEDED(rv));
+    return result;
+  }
+"""
+
+
+def write_interface(iface, fd):
+    if iface.namemap is None:
+        raise Exception("Interface was not resolved.")
+
+    # Confirm that no names of methods will overload in this interface
+    names = set()
+    def record_name(name):
+        if name in names:
+            raise Exception("Unexpected overloaded virtual method %s in interface %s"
+                            % (name, iface.name))
+        names.add(name)
+    for m in iface.members:
+        if type(m) == xpidl.Attribute:
+            record_name(attributeNativeName(m, getter=True))
+            if not m.readonly:
+                record_name(attributeNativeName(m, getter=False))
+        elif type(m) == xpidl.Method:
+            record_name(methodNativeName(m))
+
+    def write_const_decls(g):
+        fd.write("  enum {\n")
+        enums = []
+        for c in g:
+            printComments(fd, c.doccomments, '  ')
+            basetype = c.basetype
+            value = c.getValue()
+            enums.append("    %(name)s = %(value)s%(signed)s" % {
+                         'name': c.name,
+                         'value': value,
+                         'signed': (not basetype.signed) and 'U' or ''})
+        fd.write(",\n".join(enums))
+        fd.write("\n  };\n\n")
+
+    def write_method_decl(m):
+        printComments(fd, m.doccomments, '  ')
+
+        fd.write("  /* %s */\n" % m.toIDL())
+        fd.write("  %s = 0;\n\n" % methodAsNative(m))
+
+    def write_attr_decl(a):
+        printComments(fd, a.doccomments, '  ')
+
+        fd.write("  /* %s */\n" % a.toIDL())
+
+        fd.write("  %s = 0;\n" % attributeAsNative(a, True))
+        if a.infallible:
+            fd.write(attr_infallible_tmpl %
+                     {'realtype': a.realtype.nativeType('in'),
+                      'nativename': attributeNativeName(a, getter=True),
+                      'args': '' if not a.implicit_jscontext else 'JSContext* cx',
+                      'argnames': '' if not a.implicit_jscontext else 'cx, '})
+
+        if not a.readonly:
+            fd.write("  %s = 0;\n" % attributeAsNative(a, False))
+        fd.write("\n")
+
+    defname = iface.name.upper()
+    if iface.name[0:2] == 'ns':
+        defname = 'NS_' + defname[2:]
+
+    names = uuid_decoder.match(iface.attributes.uuid).groupdict()
+    m3str = names['m3'] + names['m4']
+    names['m3joined'] = ", ".join(["0x%s" % m3str[i:i+2] for i in xrange(0, 16, 2)])
+
+    if iface.name[2] == 'I':
+        implclass = iface.name[:2] + iface.name[3:]
+    else:
+        implclass = '_MYCLASS_'
+
+    names.update({'defname': defname,
+                  'macroname': iface.name.upper(),
+                  'name': iface.name,
+                  'iid': iface.attributes.uuid,
+                  'implclass': implclass})
+
+    fd.write(iface_header % names)
+
+    printComments(fd, iface.doccomments, '')
+
+    fd.write("class ")
+    foundcdata = False
+    for m in iface.members:
+        if isinstance(m, xpidl.CDATA):
+            foundcdata = True
+
+    if not foundcdata:
+        fd.write("NS_NO_VTABLE ")
+
+    if iface.attributes.deprecated:
+        fd.write("MOZ_DEPRECATED ")
+    fd.write(iface.name)
+    if iface.base:
+        fd.write(" : public %s" % iface.base)
+    fd.write(iface_prolog % names)
+
+    for key, group in itertools.groupby(iface.members, key=type):
+        if key == xpidl.ConstMember:
+            write_const_decls(group)  # iterator of all the consts
+        else:
+            for member in group:
+                if key == xpidl.Attribute:
+                    write_attr_decl(member)
+                elif key == xpidl.Method:
+                    write_method_decl(member)
+                elif key == xpidl.CDATA:
+                    fd.write(" %s" % member.data)
+                else:
+                    raise Exception("Unexpected interface member: %s" % member)
+
+    fd.write(iface_epilog % names)
+
+    def writeDeclaration(fd, iface, virtual):
+        declType = "NS_IMETHOD" if virtual else "NS_METHOD"
+        suffix = " override" if virtual else ""
+        for member in iface.members:
+            if isinstance(member, xpidl.Attribute):
+                if member.infallible:
+                    fd.write("\\\n  using %s::%s; " % (iface.name, attributeNativeName(member, True)))
+                fd.write("\\\n  %s%s; " % (attributeAsNative(member, True, declType), suffix))
+                if not member.readonly:
+                    fd.write("\\\n  %s%s; " % (attributeAsNative(member, False, declType), suffix))
+            elif isinstance(member, xpidl.Method):
+                fd.write("\\\n  %s%s; " % (methodAsNative(member, declType), suffix))
+        if len(iface.members) == 0:
+            fd.write('\\\n  /* no methods! */')
+        elif not member.kind in ('attribute', 'method'):
+            fd.write('\\')
+
+    writeDeclaration(fd, iface, True);
+    fd.write(iface_nonvirtual % names)
+    writeDeclaration(fd, iface, False);
+    fd.write(iface_forward % names)
+
+    def emitTemplate(forward_infallible, tmpl, tmpl_notxpcom=None):
+        if tmpl_notxpcom is None:
+            tmpl_notxpcom = tmpl
+        for member in iface.members:
+            if isinstance(member, xpidl.Attribute):
+                if forward_infallible and member.infallible:
+                    fd.write("\\\n  using %s::%s; " % (iface.name, attributeNativeName(member, True)))
+                fd.write(tmpl % {'asNative': attributeAsNative(member, True),
+                                 'nativeName': attributeNativeName(member, True),
+                                 'paramList': attributeParamNames(member)})
+                if not member.readonly:
+                    fd.write(tmpl % {'asNative': attributeAsNative(member, False),
+                                     'nativeName': attributeNativeName(member, False),
+                                     'paramList': attributeParamNames(member)})
+            elif isinstance(member, xpidl.Method):
+                if member.notxpcom:
+                    fd.write(tmpl_notxpcom % {'asNative': methodAsNative(member),
+                                              'nativeName': methodNativeName(member),
+                                              'paramList': paramlistNames(member)})
+                else:
+                    fd.write(tmpl % {'asNative': methodAsNative(member),
+                                     'nativeName': methodNativeName(member),
+                                     'paramList': paramlistNames(member)})
+        if len(iface.members) == 0:
+            fd.write('\\\n  /* no methods! */')
+        elif not member.kind in ('attribute', 'method'):
+            fd.write('\\')
+
+    emitTemplate(True,
+                 "\\\n  %(asNative)s override { return _to %(nativeName)s(%(paramList)s); } ")
+
+    fd.write(iface_forward_safe % names)
+
+    # Don't try to safely forward notxpcom functions, because we have no
+    # sensible default error return.  Instead, the caller will have to
+    # implement them.
+    emitTemplate(False,
+                 "\\\n  %(asNative)s override { return !_to ? NS_ERROR_NULL_POINTER : _to->%(nativeName)s(%(paramList)s); } ",
+                 "\\\n  %(asNative)s override; ")
+
+    fd.write(iface_template_prolog % names)
+
+    for member in iface.members:
+        if isinstance(member, xpidl.ConstMember) or isinstance(member, xpidl.CDATA):
+            continue
+        fd.write("/* %s */\n" % member.toIDL())
+        if isinstance(member, xpidl.Attribute):
+            fd.write(example_tmpl % {'implclass': implclass,
+                                     'returntype': attributeReturnType(member, 'NS_IMETHODIMP'),
+                                     'nativeName': attributeNativeName(member, True),
+                                     'paramList': attributeParamlist(member, True)})
+            if not member.readonly:
+                fd.write(example_tmpl % {'implclass': implclass,
+                                         'returntype': attributeReturnType(member, 'NS_IMETHODIMP'),
+                                         'nativeName': attributeNativeName(member, False),
+                                         'paramList': attributeParamlist(member, False)})
+        elif isinstance(member, xpidl.Method):
+            fd.write(example_tmpl % {'implclass': implclass,
+                                     'returntype': methodReturnType(member, 'NS_IMETHODIMP'),
+                                     'nativeName': methodNativeName(member),
+                                     'paramList': paramlistAsNative(member, empty='')})
+        fd.write('\n')
+
+    fd.write(iface_template_epilog)
+
+
+def main(outputfile):
+    cachedir = '.'
+    if not os.path.isdir(cachedir):
+        os.mkdir(cachedir)
+    sys.path.append(cachedir)
+
+    # Delete the lex/yacc files.  Ply is too stupid to regenerate them
+    # properly
+    for fileglobs in [os.path.join(cachedir, f) for f in ["xpidllex.py*", "xpidlyacc.py*"]]:
+        for filename in glob.glob(fileglobs):
+            os.remove(filename)
+
+    # Instantiate the parser.
+    p = xpidl.IDLParser(outputdir=cachedir)
+
+if __name__ == '__main__':
+    main(None)
diff --git a/xpcom/idl-parser/xpidl/moz.build b/xpcom/idl-parser/xpidl/moz.build
new file mode 100644
index 000000000..33c1e7b13
--- /dev/null
+++ b/xpcom/idl-parser/xpidl/moz.build
@@ -0,0 +1,29 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+PYTHON_UNIT_TESTS += [
+    'runtests.py',
+]
+
+GENERATED_FILES += [
+    ('xpidl.stub', 'xpidllex.py', 'xpidlyacc.py'),
+]
+
+GENERATED_FILES[('xpidl.stub', 'xpidllex.py', 'xpidlyacc.py')].script = 'header.py:main'
+
+SDK_FILES.bin += [
+    '!xpidllex.py',
+    '!xpidlyacc.py',
+    'header.py',
+    'typelib.py',
+    'xpidl.py',
+]
+
+SDK_FILES.bin.ply += [
+    '/other-licenses/ply/ply/__init__.py',
+    '/other-licenses/ply/ply/lex.py',
+    '/other-licenses/ply/ply/yacc.py',
+]
diff --git a/xpcom/idl-parser/xpidl/runtests.py b/xpcom/idl-parser/xpidl/runtests.py
new file mode 100644
index 000000000..89222d546
--- /dev/null
+++ b/xpcom/idl-parser/xpidl/runtests.py
@@ -0,0 +1,114 @@
+#!/usr/bin/env python
+#
+# Any copyright is dedicated to the Public Domain.
+# http://creativecommons.org/publicdomain/zero/1.0/
+#
+# Unit tests for xpidl.py
+
+import mozunit
+import unittest
+import xpidl
+import header
+
+
+class TestParser(unittest.TestCase):
+    def setUp(self):
+        self.p = xpidl.IDLParser()
+
+    def testEmpty(self):
+        i = self.p.parse("", filename='f')
+        self.assertTrue(isinstance(i, xpidl.IDL))
+        self.assertEqual([], i.productions)
+
+    def testForwardInterface(self):
+        i = self.p.parse("interface foo;", filename='f')
+        self.assertTrue(isinstance(i, xpidl.IDL))
+        self.assertTrue(isinstance(i.productions[0], xpidl.Forward))
+        self.assertEqual("foo", i.productions[0].name)
+
+    def testInterface(self):
+        i = self.p.parse("[uuid(abc)] interface foo {};", filename='f')
+        self.assertTrue(isinstance(i, xpidl.IDL))
+        self.assertTrue(isinstance(i.productions[0], xpidl.Interface))
+        self.assertEqual("foo", i.productions[0].name)
+
+    def testAttributes(self):
+        i = self.p.parse("[scriptable, builtinclass, function, deprecated, uuid(abc)] interface foo {};", filename='f')
+        self.assertTrue(isinstance(i, xpidl.IDL))
+        self.assertTrue(isinstance(i.productions[0], xpidl.Interface))
+        iface = i.productions[0]
+        self.assertEqual("foo", iface.name)
+        self.assertTrue(iface.attributes.scriptable)
+        self.assertTrue(iface.attributes.builtinclass)
+        self.assertTrue(iface.attributes.function)
+        self.assertTrue(iface.attributes.deprecated)
+
+        i = self.p.parse("[noscript, uuid(abc)] interface foo {};", filename='f')
+        self.assertTrue(isinstance(i, xpidl.IDL))
+        self.assertTrue(isinstance(i.productions[0], xpidl.Interface))
+        iface = i.productions[0]
+        self.assertEqual("foo", iface.name)
+        self.assertTrue(iface.attributes.noscript)
+
+    def testMethod(self):
+        i = self.p.parse("""[uuid(abc)] interface foo {
+void bar();
+};""", filename='f')
+        self.assertTrue(isinstance(i, xpidl.IDL))
+        self.assertTrue(isinstance(i.productions[0], xpidl.Interface))
+        iface = i.productions[0]
+        m = iface.members[0]
+        self.assertTrue(isinstance(m, xpidl.Method))
+        self.assertEqual("bar", m.name)
+        self.assertEqual("void", m.type)
+
+    def testMethodParams(self):
+        i = self.p.parse("""[uuid(abc)] interface foo {
+long bar(in long a, in float b, [array] in long c);
+};""", filename='f')
+        i.resolve([], self.p)
+        self.assertTrue(isinstance(i, xpidl.IDL))
+        self.assertTrue(isinstance(i.productions[0], xpidl.Interface))
+        iface = i.productions[0]
+        m = iface.members[0]
+        self.assertTrue(isinstance(m, xpidl.Method))
+        self.assertEqual("bar", m.name)
+        self.assertEqual("long", m.type)
+        self.assertEqual(3, len(m.params))
+        self.assertEqual("long", m.params[0].type)
+        self.assertEqual("in", m.params[0].paramtype)
+        self.assertEqual("float", m.params[1].type)
+        self.assertEqual("in", m.params[1].paramtype)
+        self.assertEqual("long", m.params[2].type)
+        self.assertEqual("in", m.params[2].paramtype)
+        self.assertTrue(isinstance(m.params[2].realtype, xpidl.Array))
+        self.assertEqual("long", m.params[2].realtype.type.name)
+
+    def testAttribute(self):
+        i = self.p.parse("""[uuid(abc)] interface foo {
+attribute long bar;
+};""", filename='f')
+        self.assertTrue(isinstance(i, xpidl.IDL))
+        self.assertTrue(isinstance(i.productions[0], xpidl.Interface))
+        iface = i.productions[0]
+        a = iface.members[0]
+        self.assertTrue(isinstance(a, xpidl.Attribute))
+        self.assertEqual("bar", a.name)
+        self.assertEqual("long", a.type)
+
+    def testOverloadedVirtual(self):
+        i = self.p.parse("""[uuid(abc)] interface foo {
+attribute long bar;
+void getBar();
+};""", filename='f')
+        self.assertTrue(isinstance(i, xpidl.IDL))
+        class FdMock:
+            def write(self, s):
+                pass
+        try:
+            header.print_header(i, FdMock(), filename='f')
+        except Exception as e:
+            self.assertEqual(e.args[0], "Unexpected overloaded virtual method GetBar in interface foo")
+
+if __name__ == '__main__':
+    mozunit.main()
diff --git a/xpcom/idl-parser/xpidl/typelib.py b/xpcom/idl-parser/xpidl/typelib.py
new file mode 100644
index 000000000..911e3873d
--- /dev/null
+++ b/xpcom/idl-parser/xpidl/typelib.py
@@ -0,0 +1,307 @@
+#!/usr/bin/env python
+# typelib.py - Generate XPCOM typelib files from IDL.
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+"""Generate an XPIDL typelib for the IDL files specified on the command line"""
+
+import os
+import sys
+import xpidl
+import xpt
+
+# A map of xpidl.py types to xpt.py types
+TypeMap = {
+    # nsresult is not strictly an xpidl.py type, but it's useful here
+    'nsresult':           xpt.Type.Tags.uint32,
+    # builtins
+    'boolean':            xpt.Type.Tags.boolean,
+    'void':               xpt.Type.Tags.void,
+    'int16_t':            xpt.Type.Tags.int16,
+    'int32_t':            xpt.Type.Tags.int32,
+    'int64_t':            xpt.Type.Tags.int64,
+    'uint8_t':            xpt.Type.Tags.uint8,
+    'uint16_t':           xpt.Type.Tags.uint16,
+    'uint32_t':           xpt.Type.Tags.uint32,
+    'uint64_t':           xpt.Type.Tags.uint64,
+    'octet':              xpt.Type.Tags.uint8,
+    'short':              xpt.Type.Tags.int16,
+    'long':               xpt.Type.Tags.int32,
+    'long long':          xpt.Type.Tags.int64,
+    'unsigned short':     xpt.Type.Tags.uint16,
+    'unsigned long':      xpt.Type.Tags.uint32,
+    'unsigned long long': xpt.Type.Tags.uint64,
+    'float':              xpt.Type.Tags.float,
+    'double':             xpt.Type.Tags.double,
+    'char':               xpt.Type.Tags.char,
+    'string':             xpt.Type.Tags.char_ptr,
+    'wchar':              xpt.Type.Tags.wchar_t,
+    'wstring':            xpt.Type.Tags.wchar_t_ptr,
+    # special types
+    'nsid':               xpt.Type.Tags.nsIID,
+    'domstring':          xpt.Type.Tags.DOMString,
+    'astring':            xpt.Type.Tags.AString,
+    'utf8string':         xpt.Type.Tags.UTF8String,
+    'cstring':            xpt.Type.Tags.CString,
+    'jsval':              xpt.Type.Tags.jsval
+}
+
+
+# XXXkhuey dipper types should go away (bug 677784)
+def isDipperType(type):
+    return type == xpt.Type.Tags.DOMString or type == xpt.Type.Tags.AString or type == xpt.Type.Tags.CString or type == xpt.Type.Tags.UTF8String
+
+
+def build_interface(iface, ifaces):
+    def get_type(type, calltype, iid_is=None, size_is=None):
+        """ Return the appropriate xpt.Type object for this param """
+
+        while isinstance(type, xpidl.Typedef):
+            type = type.realtype
+
+        if isinstance(type, xpidl.Builtin):
+            if type.name == 'string' and size_is is not None:
+                return xpt.StringWithSizeType(size_is, size_is)
+            elif type.name == 'wstring' and size_is is not None:
+                return xpt.WideStringWithSizeType(size_is, size_is)
+            else:
+                tag = TypeMap[type.name]
+                isPtr = (tag == xpt.Type.Tags.char_ptr or tag == xpt.Type.Tags.wchar_t_ptr)
+                return xpt.SimpleType(tag,
+                                      pointer=isPtr,
+                                      reference=False)
+
+        if isinstance(type, xpidl.Array):
+            # NB: For an Array<T> we pass down the iid_is to get the type of T.
+            #     This allows Arrays of InterfaceIs types to work.
+            return xpt.ArrayType(get_type(type.type, calltype, iid_is), size_is,
+                                 #XXXkhuey length_is duplicates size_is (bug 677788),
+                                 size_is)
+
+        if isinstance(type, xpidl.Interface) or isinstance(type, xpidl.Forward):
+            xptiface = None
+            for i in ifaces:
+                if i.name == type.name:
+                    xptiface = i
+
+            if not xptiface:
+                xptiface = xpt.Interface(name=type.name)
+                ifaces.append(xptiface)
+
+            return xpt.InterfaceType(xptiface)
+
+        if isinstance(type, xpidl.Native):
+            if type.specialtype:
+                # XXXkhuey jsval is marked differently in the typelib and in the headers :-(
+                isPtr = (type.isPtr(calltype) or type.isRef(calltype)) and not type.specialtype == 'jsval'
+                isRef = type.isRef(calltype) and not type.specialtype == 'jsval'
+                return xpt.SimpleType(TypeMap[type.specialtype],
+                                      pointer=isPtr,
+                                      reference=isRef)
+            elif iid_is is not None:
+                return xpt.InterfaceIsType(iid_is)
+            else:
+                # void ptr
+                return xpt.SimpleType(TypeMap['void'],
+                                      pointer=True,
+                                      reference=False)
+
+        raise Exception("Unknown type!")
+
+    def get_nsresult():
+        return xpt.SimpleType(TypeMap['nsresult'])
+
+    def build_nsresult_param():
+        return xpt.Param(get_nsresult())
+
+    def get_result_type(m):
+        if not m.notxpcom:
+            return get_nsresult()
+
+        return get_type(m.realtype, '')
+
+    def build_result_param(m):
+        return xpt.Param(get_result_type(m))
+
+    def build_retval_param(m):
+        type = get_type(m.realtype, 'out')
+        if isDipperType(type.tag):
+            # NB: The retval bit needs to be set here, contrary to what the
+            # xpt spec says.
+            return xpt.Param(type, in_=True, retval=True, dipper=True)
+        return xpt.Param(type, in_=False, out=True, retval=True)
+
+    def build_attr_param(a, getter=False, setter=False):
+        if not (getter or setter):
+            raise Exception("Attribute param must be for a getter or a setter!")
+
+        type = get_type(a.realtype, getter and 'out' or 'in')
+        if setter:
+            return xpt.Param(type)
+        else:
+            if isDipperType(type.tag):
+                # NB: The retval bit needs to be set here, contrary to what the
+                # xpt spec says.
+                return xpt.Param(type, in_=True, retval=True, dipper=True)
+            return xpt.Param(type, in_=False, out=True, retval=True)
+
+    if iface.namemap is None:
+        raise Exception("Interface was not resolved.")
+
+    consts = []
+    methods = []
+
+    def build_const(c):
+        consts.append(xpt.Constant(c.name, get_type(c.basetype, ''), c.getValue()))
+
+    def build_method(m):
+        params = []
+
+        def build_param(p):
+            def findattr(p, attr):
+                if hasattr(p, attr) and getattr(p, attr):
+                    for i, param in enumerate(m.params):
+                        if param.name == getattr(p, attr):
+                            return i
+                    return None
+
+            iid_is = findattr(p, 'iid_is')
+            size_is = findattr(p, 'size_is')
+
+            in_ = p.paramtype.count("in")
+            out = p.paramtype.count("out")
+            dipper = False
+            type = get_type(p.realtype, p.paramtype, iid_is=iid_is, size_is=size_is)
+            if out and isDipperType(type.tag):
+                out = False
+                dipper = True
+
+            return xpt.Param(type, in_, out, p.retval, p.shared, dipper, p.optional)
+
+        for p in m.params:
+            params.append(build_param(p))
+
+        if not m.notxpcom and m.realtype.name != 'void':
+            params.append(build_retval_param(m))
+
+        methods.append(xpt.Method(m.name, build_result_param(m), params,
+                                  getter=False, setter=False, notxpcom=m.notxpcom,
+                                  constructor=False, hidden=m.noscript,
+                                  optargc=m.optional_argc,
+                                  implicit_jscontext=m.implicit_jscontext))
+
+    def build_attr(a):
+        # Write the getter
+        methods.append(xpt.Method(a.name, build_nsresult_param(),
+                                  [build_attr_param(a, getter=True)],
+                                  getter=True, setter=False,
+                                  constructor=False, hidden=a.noscript,
+                                  optargc=False,
+                                  implicit_jscontext=a.implicit_jscontext))
+
+        # And maybe the setter
+        if not a.readonly:
+            methods.append(xpt.Method(a.name, build_nsresult_param(),
+                                      [build_attr_param(a, setter=True)],
+                                      getter=False, setter=True,
+                                      constructor=False, hidden=a.noscript,
+                                      optargc=False,
+                                      implicit_jscontext=a.implicit_jscontext))
+
+    for member in iface.members:
+        if isinstance(member, xpidl.ConstMember):
+            build_const(member)
+        elif isinstance(member, xpidl.Attribute):
+            build_attr(member)
+        elif isinstance(member, xpidl.Method):
+            build_method(member)
+        elif isinstance(member, xpidl.CDATA):
+            pass
+        else:
+            raise Exception("Unexpected interface member: %s" % member)
+
+    parent = None
+    if iface.base:
+        for i in ifaces:
+            if i.name == iface.base:
+                parent = i
+        if not parent:
+            parent = xpt.Interface(name=iface.base)
+            ifaces.append(parent)
+
+    return xpt.Interface(iface.name, iface.attributes.uuid, methods=methods,
+                         constants=consts, resolved=True, parent=parent,
+                         scriptable=iface.attributes.scriptable,
+                         function=iface.attributes.function,
+                         builtinclass=iface.attributes.builtinclass,
+                         main_process_scriptable_only=iface.attributes.main_process_scriptable_only)
+
+
+def write_typelib(idl, fd, filename):
+    """ Generate the typelib. """
+
+    # We only care about interfaces that are scriptable.
+    ifaces = []
+    for p in idl.productions:
+        if p.kind == 'interface' and p.attributes.scriptable:
+            ifaces.append(build_interface(p, ifaces))
+
+    typelib = xpt.Typelib(interfaces=ifaces)
+    typelib.writefd(fd)
+
+if __name__ == '__main__':
+    from optparse import OptionParser
+    o = OptionParser()
+    o.add_option('-I', action='append', dest='incdirs', default=['.'],
+                 help="Directory to search for imported files")
+    o.add_option('--cachedir', dest='cachedir', default=None,
+                 help="Directory in which to cache lex/parse tables.")
+    o.add_option('-o', dest='outfile', default=None,
+                 help="Output file")
+    o.add_option('-d', dest='depfile', default=None,
+                 help="Generate a make dependency file")
+    o.add_option('--regen', action='store_true', dest='regen', default=False,
+                 help="Regenerate IDL Parser cache")
+    options, args = o.parse_args()
+    file = args[0] if args else None
+
+    if options.cachedir is not None:
+        if not os.path.isdir(options.cachedir):
+            os.mkdir(options.cachedir)
+        sys.path.append(options.cachedir)
+
+    if options.regen:
+        if options.cachedir is None:
+            print >>sys.stderr, "--regen requires --cachedir"
+            sys.exit(1)
+
+        p = xpidl.IDLParser(outputdir=options.cachedir, regen=True)
+        sys.exit(0)
+
+    if options.depfile is not None and options.outfile is None:
+        print >>sys.stderr, "-d requires -o"
+        sys.exit(1)
+
+    if options.outfile is not None:
+        outfd = open(options.outfile, 'wb')
+        closeoutfd = True
+    else:
+        raise "typelib generation requires an output file"
+
+    p = xpidl.IDLParser(outputdir=options.cachedir)
+    idl = p.parse(open(file).read(), filename=file)
+    idl.resolve(options.incdirs, p)
+    write_typelib(idl, outfd, file)
+
+    if closeoutfd:
+        outfd.close()
+
+    if options.depfile is not None:
+        depfd = open(options.depfile, 'w')
+        deps = [dep.replace('\\', '/') for dep in idl.deps]
+
+        print >>depfd, "%s: %s" % (options.outfile, " ".join(deps))
+        for dep in deps:
+            print >>depfd, "%s:" % dep
diff --git a/xpcom/idl-parser/xpidl/xpidl.py b/xpcom/idl-parser/xpidl/xpidl.py
new file mode 100755
index 000000000..8b2d8c884
--- /dev/null
+++ b/xpcom/idl-parser/xpidl/xpidl.py
@@ -0,0 +1,1465 @@
+#!/usr/bin/env python
+# xpidl.py - A parser for cross-platform IDL (XPIDL) files.
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+"""A parser for cross-platform IDL (XPIDL) files."""
+
+import sys
+import os.path
+import re
+from ply import lex
+from ply import yacc
+
+"""A type conforms to the following pattern:
+
+    def isScriptable(self):
+        'returns True or False'
+
+    def nativeType(self, calltype):
+        'returns a string representation of the native type
+        calltype must be 'in', 'out', or 'inout'
+
+Interface members const/method/attribute conform to the following pattern:
+
+    name = 'string'
+
+    def toIDL(self):
+        'returns the member signature as IDL'
+"""
+
+
+def attlistToIDL(attlist):
+    if len(attlist) == 0:
+        return ''
+
+    attlist = list(attlist)
+    attlist.sort(cmp=lambda a, b: cmp(a[0], b[0]))
+
+    return '[%s] ' % ','.join(["%s%s" % (name, value is not None and '(%s)' % value or '')
+                              for name, value, aloc in attlist])
+
+_paramsHardcode = {
+    2: ('array', 'shared', 'iid_is', 'size_is', 'retval'),
+    3: ('array', 'size_is', 'const'),
+}
+
+
+def paramAttlistToIDL(attlist):
+    if len(attlist) == 0:
+        return ''
+
+    # Hack alert: g_hash_table_foreach is pretty much unimitatable... hardcode
+    # quirk
+    attlist = list(attlist)
+    sorted = []
+    if len(attlist) in _paramsHardcode:
+        for p in _paramsHardcode[len(attlist)]:
+            i = 0
+            while i < len(attlist):
+                if attlist[i][0] == p:
+                    sorted.append(attlist[i])
+                    del attlist[i]
+                    continue
+
+                i += 1
+
+    sorted.extend(attlist)
+
+    return '[%s] ' % ', '.join(["%s%s" % (name, value is not None and ' (%s)' % value or '')
+                                for name, value, aloc in sorted])
+
+
+def unaliasType(t):
+    while t.kind == 'typedef':
+        t = t.realtype
+    assert t is not None
+    return t
+
+
+def getBuiltinOrNativeTypeName(t):
+    t = unaliasType(t)
+    if t.kind == 'builtin':
+        return t.name
+    elif t.kind == 'native':
+        assert t.specialtype is not None
+        return '[%s]' % t.specialtype
+    else:
+        return None
+
+
+class BuiltinLocation(object):
+    def get(self):
+        return "<builtin type>"
+
+    def __str__(self):
+        return self.get()
+
+
+class Builtin(object):
+    kind = 'builtin'
+    location = BuiltinLocation
+
+    def __init__(self, name, nativename, signed=False, maybeConst=False):
+        self.name = name
+        self.nativename = nativename
+        self.signed = signed
+        self.maybeConst = maybeConst
+
+    def isScriptable(self):
+        return True
+
+    def nativeType(self, calltype, shared=False, const=False):
+        if const:
+            print >>sys.stderr, IDLError("[const] doesn't make sense on builtin types.", self.location, warning=True)
+            const = 'const '
+        elif calltype == 'in' and self.nativename.endswith('*'):
+            const = 'const '
+        elif shared:
+            if not self.nativename.endswith('*'):
+                raise IDLError("[shared] not applicable to non-pointer types.", self.location)
+            const = 'const '
+        else:
+            const = ''
+        return "%s%s %s" % (const, self.nativename,
+                            calltype != 'in' and '*' or '')
+
+builtinNames = [
+    Builtin('boolean', 'bool'),
+    Builtin('void', 'void'),
+    Builtin('octet', 'uint8_t'),
+    Builtin('short', 'int16_t', True, True),
+    Builtin('long', 'int32_t', True, True),
+    Builtin('long long', 'int64_t', True, False),
+    Builtin('unsigned short', 'uint16_t', False, True),
+    Builtin('unsigned long', 'uint32_t', False, True),
+    Builtin('unsigned long long', 'uint64_t', False, False),
+    Builtin('float', 'float', True, False),
+    Builtin('double', 'double', True, False),
+    Builtin('char', 'char', True, False),
+    Builtin('string', 'char *', False, False),
+    Builtin('wchar', 'char16_t', False, False),
+    Builtin('wstring', 'char16_t *', False, False),
+]
+
+builtinMap = {}
+for b in builtinNames:
+    builtinMap[b.name] = b
+
+
+class Location(object):
+    _line = None
+
+    def __init__(self, lexer, lineno, lexpos):
+        self._lineno = lineno
+        self._lexpos = lexpos
+        self._lexdata = lexer.lexdata
+        self._file = getattr(lexer, 'filename', "<unknown>")
+
+    def __eq__(self, other):
+        return (self._lexpos == other._lexpos and
+                self._file == other._file)
+
+    def resolve(self):
+        if self._line:
+            return
+
+        startofline = self._lexdata.rfind('\n', 0, self._lexpos) + 1
+        endofline = self._lexdata.find('\n', self._lexpos, self._lexpos + 80)
+        self._line = self._lexdata[startofline:endofline]
+        self._colno = self._lexpos - startofline
+
+    def pointerline(self):
+        def i():
+            for i in xrange(0, self._colno):
+                yield " "
+            yield "^"
+
+        return "".join(i())
+
+    def get(self):
+        self.resolve()
+        return "%s line %s:%s" % (self._file, self._lineno, self._colno)
+
+    def __str__(self):
+        self.resolve()
+        return "%s line %s:%s\n%s\n%s" % (self._file, self._lineno, self._colno,
+                                          self._line, self.pointerline())
+
+
+class NameMap(object):
+    """Map of name -> object. Each object must have a .name and .location property.
+    Setting the same name twice throws an error."""
+    def __init__(self):
+        self._d = {}
+
+    def __getitem__(self, key):
+        if key in builtinMap:
+            return builtinMap[key]
+        return self._d[key]
+
+    def __iter__(self):
+        return self._d.itervalues()
+
+    def __contains__(self, key):
+        return key in builtinMap or key in self._d
+
+    def set(self, object):
+        if object.name in builtinMap:
+            raise IDLError("name '%s' is a builtin and cannot be redeclared" % (object.name), object.location)
+        if object.name.startswith("_"):
+            object.name = object.name[1:]
+        if object.name in self._d:
+            old = self._d[object.name]
+            if old == object:
+                return
+            if isinstance(old, Forward) and isinstance(object, Interface):
+                self._d[object.name] = object
+            elif isinstance(old, Interface) and isinstance(object, Forward):
+                pass
+            else:
+                raise IDLError("name '%s' specified twice. Previous location: %s" % (object.name, self._d[object.name].location), object.location)
+        else:
+            self._d[object.name] = object
+
+    def get(self, id, location):
+        try:
+            return self[id]
+        except KeyError:
+            raise IDLError("Name '%s' not found", location)
+
+
+class IDLError(Exception):
+    def __init__(self, message, location, warning=False):
+        self.message = message
+        self.location = location
+        self.warning = warning
+
+    def __str__(self):
+        return "%s: %s, %s" % (self.warning and 'warning' or 'error',
+                               self.message, self.location)
+
+
+class Include(object):
+    kind = 'include'
+
+    def __init__(self, filename, location):
+        self.filename = filename
+        self.location = location
+
+    def __str__(self):
+        return "".join(["include '%s'\n" % self.filename])
+
+    def resolve(self, parent):
+        def incfiles():
+            yield self.filename
+            for dir in parent.incdirs:
+                yield os.path.join(dir, self.filename)
+
+        for file in incfiles():
+            if not os.path.exists(file):
+                continue
+
+            self.IDL = parent.parser.parse(open(file).read(), filename=file)
+            self.IDL.resolve(parent.incdirs, parent.parser)
+            for type in self.IDL.getNames():
+                parent.setName(type)
+            parent.deps.extend(self.IDL.deps)
+            return
+
+        raise IDLError("File '%s' not found" % self.filename, self.location)
+
+
+class IDL(object):
+    def __init__(self, productions):
+        self.productions = productions
+        self.deps = []
+
+    def setName(self, object):
+        self.namemap.set(object)
+
+    def getName(self, id, location):
+        try:
+            return self.namemap[id]
+        except KeyError:
+            raise IDLError("type '%s' not found" % id, location)
+
+    def hasName(self, id):
+        return id in self.namemap
+
+    def getNames(self):
+        return iter(self.namemap)
+
+    def __str__(self):
+        return "".join([str(p) for p in self.productions])
+
+    def resolve(self, incdirs, parser):
+        self.namemap = NameMap()
+        self.incdirs = incdirs
+        self.parser = parser
+        for p in self.productions:
+            p.resolve(self)
+
+    def includes(self):
+        for p in self.productions:
+            if p.kind == 'include':
+                yield p
+
+    def needsJSTypes(self):
+        for p in self.productions:
+            if p.kind == 'interface' and p.needsJSTypes():
+                return True
+        return False
+
+
+class CDATA(object):
+    kind = 'cdata'
+    _re = re.compile(r'\n+')
+
+    def __init__(self, data, location):
+        self.data = self._re.sub('\n', data)
+        self.location = location
+
+    def resolve(self, parent):
+        pass
+
+    def __str__(self):
+        return "cdata: %s\n\t%r\n" % (self.location.get(), self.data)
+
+    def count(self):
+        return 0
+
+
+class Typedef(object):
+    kind = 'typedef'
+
+    def __init__(self, type, name, location, doccomments):
+        self.type = type
+        self.name = name
+        self.location = location
+        self.doccomments = doccomments
+
+    def __eq__(self, other):
+        return self.name == other.name and self.type == other.type
+
+    def resolve(self, parent):
+        parent.setName(self)
+        self.realtype = parent.getName(self.type, self.location)
+
+    def isScriptable(self):
+        return self.realtype.isScriptable()
+
+    def nativeType(self, calltype):
+        return "%s %s" % (self.name,
+                          calltype != 'in' and '*' or '')
+
+    def __str__(self):
+        return "typedef %s %s\n" % (self.type, self.name)
+
+
+class Forward(object):
+    kind = 'forward'
+
+    def __init__(self, name, location, doccomments):
+        self.name = name
+        self.location = location
+        self.doccomments = doccomments
+
+    def __eq__(self, other):
+        return other.kind == 'forward' and other.name == self.name
+
+    def resolve(self, parent):
+        # Hack alert: if an identifier is already present, move the doccomments
+        # forward.
+        if parent.hasName(self.name):
+            for i in xrange(0, len(parent.productions)):
+                if parent.productions[i] is self:
+                    break
+            for i in xrange(i + 1, len(parent.productions)):
+                if hasattr(parent.productions[i], 'doccomments'):
+                    parent.productions[i].doccomments[0:0] = self.doccomments
+                    break
+
+        parent.setName(self)
+
+    def isScriptable(self):
+        return True
+
+    def nativeType(self, calltype):
+        return "%s %s" % (self.name,
+                          calltype != 'in' and '* *' or '*')
+
+    def __str__(self):
+        return "forward-declared %s\n" % self.name
+
+
+class Native(object):
+    kind = 'native'
+
+    modifier = None
+    specialtype = None
+
+    specialtypes = {
+        'nsid': None,
+        'domstring': 'nsAString',
+        'utf8string': 'nsACString',
+        'cstring': 'nsACString',
+        'astring': 'nsAString',
+        'jsval': 'JS::Value'
+        }
+
+    def __init__(self, name, nativename, attlist, location):
+        self.name = name
+        self.nativename = nativename
+        self.location = location
+
+        for name, value, aloc in attlist:
+            if value is not None:
+                raise IDLError("Unexpected attribute value", aloc)
+            if name in ('ptr', 'ref'):
+                if self.modifier is not None:
+                    raise IDLError("More than one ptr/ref modifier", aloc)
+                self.modifier = name
+            elif name in self.specialtypes.keys():
+                if self.specialtype is not None:
+                    raise IDLError("More than one special type", aloc)
+                self.specialtype = name
+                if self.specialtypes[name] is not None:
+                    self.nativename = self.specialtypes[name]
+            else:
+                raise IDLError("Unexpected attribute", aloc)
+
+    def __eq__(self, other):
+        return (self.name == other.name and
+                self.nativename == other.nativename and
+                self.modifier == other.modifier and
+                self.specialtype == other.specialtype)
+
+    def resolve(self, parent):
+        parent.setName(self)
+
+    def isScriptable(self):
+        if self.specialtype is None:
+            return False
+
+        if self.specialtype == 'nsid':
+            return self.modifier is not None
+
+        return self.modifier == 'ref'
+
+    def isPtr(self, calltype):
+        return self.modifier == 'ptr'
+
+    def isRef(self, calltype):
+        return self.modifier == 'ref'
+
+    def nativeType(self, calltype, const=False, shared=False):
+        if shared:
+            if calltype != 'out':
+                raise IDLError("[shared] only applies to out parameters.")
+            const = True
+
+        if self.specialtype is not None and calltype == 'in':
+            const = True
+
+        if self.specialtype == 'jsval':
+            if calltype == 'out' or calltype == 'inout':
+                return "JS::MutableHandleValue "
+            return "JS::HandleValue "
+
+        if self.isRef(calltype):
+            m = '& '
+        elif self.isPtr(calltype):
+            m = '*' + ((self.modifier == 'ptr' and calltype != 'in') and '*' or '')
+        else:
+            m = calltype != 'in' and '*' or ''
+        return "%s%s %s" % (const and 'const ' or '', self.nativename, m)
+
+    def __str__(self):
+        return "native %s(%s)\n" % (self.name, self.nativename)
+
+
+class Interface(object):
+    kind = 'interface'
+
+    def __init__(self, name, attlist, base, members, location, doccomments):
+        self.name = name
+        self.attributes = InterfaceAttributes(attlist, location)
+        self.base = base
+        self.members = members
+        self.location = location
+        self.namemap = NameMap()
+        self.doccomments = doccomments
+        self.nativename = name
+
+        for m in members:
+            if not isinstance(m, CDATA):
+                self.namemap.set(m)
+
+    def __eq__(self, other):
+        return self.name == other.name and self.location == other.location
+
+    def resolve(self, parent):
+        self.idl = parent
+
+        # Hack alert: if an identifier is already present, libIDL assigns
+        # doc comments incorrectly. This is quirks-mode extraordinaire!
+        if parent.hasName(self.name):
+            for member in self.members:
+                if hasattr(member, 'doccomments'):
+                    member.doccomments[0:0] = self.doccomments
+                    break
+            self.doccomments = parent.getName(self.name, None).doccomments
+
+        if self.attributes.function:
+            has_method = False
+            for member in self.members:
+                if member.kind is 'method':
+                    if has_method:
+                        raise IDLError("interface '%s' has multiple methods, but marked 'function'" % self.name, self.location)
+                    else:
+                        has_method = True
+
+        parent.setName(self)
+        if self.base is not None:
+            realbase = parent.getName(self.base, self.location)
+            if realbase.kind != 'interface':
+                raise IDLError("interface '%s' inherits from non-interface type '%s'" % (self.name, self.base), self.location)
+
+            if self.attributes.scriptable and not realbase.attributes.scriptable:
+                print >>sys.stderr, IDLError("interface '%s' is scriptable but derives from non-scriptable '%s'" % (self.name, self.base), self.location, warning=True)
+
+            if self.attributes.scriptable and realbase.attributes.builtinclass and not self.attributes.builtinclass:
+                raise IDLError("interface '%s' is not builtinclass but derives from builtinclass '%s'" % (self.name, self.base), self.location)
+
+        for member in self.members:
+            member.resolve(self)
+
+        # The number 250 is NOT arbitrary; this number is the maximum number of
+        # stub entries defined in xpcom/reflect/xptcall/genstubs.pl
+        # Do not increase this value without increasing the number in that
+        # location, or you WILL cause otherwise unknown problems!
+        if self.countEntries() > 250 and not self.attributes.builtinclass:
+            raise IDLError("interface '%s' has too many entries" % self.name, self.location)
+
+    def isScriptable(self):
+        # NOTE: this is not whether *this* interface is scriptable... it's
+        # whether, when used as a type, it's scriptable, which is true of all
+        # interfaces.
+        return True
+
+    def nativeType(self, calltype, const=False):
+        return "%s%s %s" % (const and 'const ' or '',
+                            self.name,
+                            calltype != 'in' and '* *' or '*')
+
+    def __str__(self):
+        l = ["interface %s\n" % self.name]
+        if self.base is not None:
+            l.append("\tbase %s\n" % self.base)
+        l.append(str(self.attributes))
+        if self.members is None:
+            l.append("\tincomplete type\n")
+        else:
+            for m in self.members:
+                l.append(str(m))
+        return "".join(l)
+
+    def getConst(self, name, location):
+        # The constant may be in a base class
+        iface = self
+        while name not in iface.namemap and iface is not None:
+            iface = self.idl.getName(self.base, self.location)
+        if iface is None:
+            raise IDLError("cannot find symbol '%s'" % name)
+        c = iface.namemap.get(name, location)
+        if c.kind != 'const':
+            raise IDLError("symbol '%s' is not a constant", c.location)
+
+        return c.getValue()
+
+    def needsJSTypes(self):
+        for m in self.members:
+            if m.kind == "attribute" and m.type == "jsval":
+                return True
+            if m.kind == "method" and m.needsJSTypes():
+                return True
+        return False
+
+    def countEntries(self):
+        ''' Returns the number of entries in the vtable for this interface. '''
+        total = sum(member.count() for member in self.members)
+        if self.base is not None:
+            realbase = self.idl.getName(self.base, self.location)
+            total += realbase.countEntries()
+        return total
+
+
+class InterfaceAttributes(object):
+    uuid = None
+    scriptable = False
+    builtinclass = False
+    function = False
+    deprecated = False
+    noscript = False
+    main_process_scriptable_only = False
+
+    def setuuid(self, value):
+        self.uuid = value.lower()
+
+    def setscriptable(self):
+        self.scriptable = True
+
+    def setfunction(self):
+        self.function = True
+
+    def setnoscript(self):
+        self.noscript = True
+
+    def setbuiltinclass(self):
+        self.builtinclass = True
+
+    def setdeprecated(self):
+        self.deprecated = True
+
+    def setmain_process_scriptable_only(self):
+        self.main_process_scriptable_only = True
+
+    actions = {
+        'uuid':       (True, setuuid),
+        'scriptable': (False, setscriptable),
+        'builtinclass': (False, setbuiltinclass),
+        'function':   (False, setfunction),
+        'noscript':   (False, setnoscript),
+        'deprecated': (False, setdeprecated),
+        'object':     (False, lambda self: True),
+        'main_process_scriptable_only': (False, setmain_process_scriptable_only),
+        }
+
+    def __init__(self, attlist, location):
+        def badattribute(self):
+            raise IDLError("Unexpected interface attribute '%s'" % name, location)
+
+        for name, val, aloc in attlist:
+            hasval, action = self.actions.get(name, (False, badattribute))
+            if hasval:
+                if val is None:
+                    raise IDLError("Expected value for attribute '%s'" % name,
+                                   aloc)
+
+                action(self, val)
+            else:
+                if val is not None:
+                    raise IDLError("Unexpected value for attribute '%s'" % name,
+                                   aloc)
+
+                action(self)
+
+        if self.uuid is None:
+            raise IDLError("interface has no uuid", location)
+
+    def __str__(self):
+        l = []
+        if self.uuid:
+            l.append("\tuuid: %s\n" % self.uuid)
+        if self.scriptable:
+            l.append("\tscriptable\n")
+        if self.builtinclass:
+            l.append("\tbuiltinclass\n")
+        if self.function:
+            l.append("\tfunction\n")
+        if self.main_process_scriptable_only:
+            l.append("\tmain_process_scriptable_only\n")
+        return "".join(l)
+
+
+class ConstMember(object):
+    kind = 'const'
+
+    def __init__(self, type, name, value, location, doccomments):
+        self.type = type
+        self.name = name
+        self.value = value
+        self.location = location
+        self.doccomments = doccomments
+
+    def resolve(self, parent):
+        self.realtype = parent.idl.getName(self.type, self.location)
+        self.iface = parent
+        basetype = self.realtype
+        while isinstance(basetype, Typedef):
+            basetype = basetype.realtype
+        if not isinstance(basetype, Builtin) or not basetype.maybeConst:
+            raise IDLError("const may only be a short or long type, not %s" % self.type, self.location)
+
+        self.basetype = basetype
+
+    def getValue(self):
+        return self.value(self.iface)
+
+    def __str__(self):
+        return "\tconst %s %s = %s\n" % (self.type, self.name, self.getValue())
+
+    def count(self):
+        return 0
+
+
+class Attribute(object):
+    kind = 'attribute'
+    noscript = False
+    readonly = False
+    implicit_jscontext = False
+    nostdcall = False
+    must_use = False
+    binaryname = None
+    null = None
+    undefined = None
+    deprecated = False
+    infallible = False
+
+    def __init__(self, type, name, attlist, readonly, location, doccomments):
+        self.type = type
+        self.name = name
+        self.attlist = attlist
+        self.readonly = readonly
+        self.location = location
+        self.doccomments = doccomments
+
+        for name, value, aloc in attlist:
+            if name == 'binaryname':
+                if value is None:
+                    raise IDLError("binaryname attribute requires a value",
+                                   aloc)
+
+                self.binaryname = value
+                continue
+
+            if name == 'Null':
+                if value is None:
+                    raise IDLError("'Null' attribute requires a value", aloc)
+                if readonly:
+                    raise IDLError("'Null' attribute only makes sense for setters",
+                                   aloc)
+                if value not in ('Empty', 'Null', 'Stringify'):
+                    raise IDLError("'Null' attribute value must be 'Empty', 'Null' or 'Stringify'",
+                                   aloc)
+                self.null = value
+            elif name == 'Undefined':
+                if value is None:
+                    raise IDLError("'Undefined' attribute requires a value", aloc)
+                if readonly:
+                    raise IDLError("'Undefined' attribute only makes sense for setters",
+                                   aloc)
+                if value not in ('Empty', 'Null'):
+                    raise IDLError("'Undefined' attribute value must be 'Empty' or 'Null'",
+                                   aloc)
+                self.undefined = value
+            else:
+                if value is not None:
+                    raise IDLError("Unexpected attribute value", aloc)
+
+                if name == 'noscript':
+                    self.noscript = True
+                elif name == 'implicit_jscontext':
+                    self.implicit_jscontext = True
+                elif name == 'deprecated':
+                    self.deprecated = True
+                elif name == 'nostdcall':
+                    self.nostdcall = True
+                elif name == 'must_use':
+                    self.must_use = True
+                elif name == 'infallible':
+                    self.infallible = True
+                else:
+                    raise IDLError("Unexpected attribute '%s'" % name, aloc)
+
+    def resolve(self, iface):
+        self.iface = iface
+        self.realtype = iface.idl.getName(self.type, self.location)
+        if (self.null is not None and
+                getBuiltinOrNativeTypeName(self.realtype) != '[domstring]'):
+            raise IDLError("'Null' attribute can only be used on DOMString",
+                           self.location)
+        if (self.undefined is not None and
+                getBuiltinOrNativeTypeName(self.realtype) != '[domstring]'):
+            raise IDLError("'Undefined' attribute can only be used on DOMString",
+                           self.location)
+        if self.infallible and not self.realtype.kind == 'builtin':
+            raise IDLError('[infallible] only works on builtin types '
+                           '(numbers, booleans, and raw char types)',
+                           self.location)
+        if self.infallible and not iface.attributes.builtinclass:
+            raise IDLError('[infallible] attributes are only allowed on '
+                           '[builtinclass] interfaces',
+                           self.location)
+
+    def toIDL(self):
+        attribs = attlistToIDL(self.attlist)
+        readonly = self.readonly and 'readonly ' or ''
+        return "%s%sattribute %s %s;" % (attribs, readonly, self.type, self.name)
+
+    def isScriptable(self):
+        if not self.iface.attributes.scriptable:
+            return False
+        return not self.noscript
+
+    def __str__(self):
+        return "\t%sattribute %s %s\n" % (self.readonly and 'readonly ' or '',
+                                          self.type, self.name)
+
+    def count(self):
+        return self.readonly and 1 or 2
+
+
+class Method(object):
+    kind = 'method'
+    noscript = False
+    notxpcom = False
+    binaryname = None
+    implicit_jscontext = False
+    nostdcall = False
+    must_use = False
+    optional_argc = False
+    deprecated = False
+
+    def __init__(self, type, name, attlist, paramlist, location, doccomments, raises):
+        self.type = type
+        self.name = name
+        self.attlist = attlist
+        self.params = paramlist
+        self.location = location
+        self.doccomments = doccomments
+        self.raises = raises
+
+        for name, value, aloc in attlist:
+            if name == 'binaryname':
+                if value is None:
+                    raise IDLError("binaryname attribute requires a value",
+                                   aloc)
+
+                self.binaryname = value
+                continue
+
+            if value is not None:
+                raise IDLError("Unexpected attribute value", aloc)
+
+            if name == 'noscript':
+                self.noscript = True
+            elif name == 'notxpcom':
+                self.notxpcom = True
+            elif name == 'implicit_jscontext':
+                self.implicit_jscontext = True
+            elif name == 'optional_argc':
+                self.optional_argc = True
+            elif name == 'deprecated':
+                self.deprecated = True
+            elif name == 'nostdcall':
+                self.nostdcall = True
+            elif name == 'must_use':
+                self.must_use = True
+            else:
+                raise IDLError("Unexpected attribute '%s'" % name, aloc)
+
+        self.namemap = NameMap()
+        for p in paramlist:
+            self.namemap.set(p)
+
+    def resolve(self, iface):
+        self.iface = iface
+        self.realtype = self.iface.idl.getName(self.type, self.location)
+        for p in self.params:
+            p.resolve(self)
+        for p in self.params:
+            if p.retval and p != self.params[-1]:
+                raise IDLError("'retval' parameter '%s' is not the last parameter" % p.name, self.location)
+            if p.size_is:
+                found_size_param = False
+                for size_param in self.params:
+                    if p.size_is == size_param.name:
+                        found_size_param = True
+                        if getBuiltinOrNativeTypeName(size_param.realtype) != 'unsigned long':
+                            raise IDLError("is_size parameter must have type 'unsigned long'", self.location)
+                if not found_size_param:
+                    raise IDLError("could not find is_size parameter '%s'" % p.size_is, self.location)
+
+    def isScriptable(self):
+        if not self.iface.attributes.scriptable:
+            return False
+        return not (self.noscript or self.notxpcom)
+
+    def __str__(self):
+        return "\t%s %s(%s)\n" % (self.type, self.name, ", ".join([p.name for p in self.params]))
+
+    def toIDL(self):
+        if len(self.raises):
+            raises = ' raises (%s)' % ','.join(self.raises)
+        else:
+            raises = ''
+
+        return "%s%s %s (%s)%s;" % (attlistToIDL(self.attlist),
+                                    self.type,
+                                    self.name,
+                                    ", ".join([p.toIDL()
+                                               for p in self.params]),
+                                    raises)
+
+    def needsJSTypes(self):
+        if self.implicit_jscontext:
+            return True
+        if self.type == "jsval":
+            return True
+        for p in self.params:
+            t = p.realtype
+            if isinstance(t, Native) and t.specialtype == "jsval":
+                return True
+        return False
+
+    def count(self):
+        return 1
+
+
+class Param(object):
+    size_is = None
+    iid_is = None
+    const = False
+    array = False
+    retval = False
+    shared = False
+    optional = False
+    null = None
+    undefined = None
+
+    def __init__(self, paramtype, type, name, attlist, location, realtype=None):
+        self.paramtype = paramtype
+        self.type = type
+        self.name = name
+        self.attlist = attlist
+        self.location = location
+        self.realtype = realtype
+
+        for name, value, aloc in attlist:
+            # Put the value-taking attributes first!
+            if name == 'size_is':
+                if value is None:
+                    raise IDLError("'size_is' must specify a parameter", aloc)
+                self.size_is = value
+            elif name == 'iid_is':
+                if value is None:
+                    raise IDLError("'iid_is' must specify a parameter", aloc)
+                self.iid_is = value
+            elif name == 'Null':
+                if value is None:
+                    raise IDLError("'Null' must specify a parameter", aloc)
+                if value not in ('Empty', 'Null', 'Stringify'):
+                    raise IDLError("'Null' parameter value must be 'Empty', 'Null', or 'Stringify'",
+                                   aloc)
+                self.null = value
+            elif name == 'Undefined':
+                if value is None:
+                    raise IDLError("'Undefined' must specify a parameter", aloc)
+                if value not in ('Empty', 'Null'):
+                    raise IDLError("'Undefined' parameter value must be 'Empty' or 'Null'",
+                                   aloc)
+                self.undefined = value
+            else:
+                if value is not None:
+                    raise IDLError("Unexpected value for attribute '%s'" % name,
+                                   aloc)
+
+                if name == 'const':
+                    self.const = True
+                elif name == 'array':
+                    self.array = True
+                elif name == 'retval':
+                    self.retval = True
+                elif name == 'shared':
+                    self.shared = True
+                elif name == 'optional':
+                    self.optional = True
+                else:
+                    raise IDLError("Unexpected attribute '%s'" % name, aloc)
+
+    def resolve(self, method):
+        self.realtype = method.iface.idl.getName(self.type, self.location)
+        if self.array:
+            self.realtype = Array(self.realtype)
+        if (self.null is not None and
+                getBuiltinOrNativeTypeName(self.realtype) != '[domstring]'):
+            raise IDLError("'Null' attribute can only be used on DOMString",
+                           self.location)
+        if (self.undefined is not None and
+                getBuiltinOrNativeTypeName(self.realtype) != '[domstring]'):
+            raise IDLError("'Undefined' attribute can only be used on DOMString",
+                           self.location)
+
+    def nativeType(self):
+        kwargs = {}
+        if self.shared:
+            kwargs['shared'] = True
+        if self.const:
+            kwargs['const'] = True
+
+        try:
+            return self.realtype.nativeType(self.paramtype, **kwargs)
+        except IDLError, e:
+            raise IDLError(e.message, self.location)
+        except TypeError, e:
+            raise IDLError("Unexpected parameter attribute", self.location)
+
+    def toIDL(self):
+        return "%s%s %s %s" % (paramAttlistToIDL(self.attlist),
+                               self.paramtype,
+                               self.type,
+                               self.name)
+
+
+class Array(object):
+    def __init__(self, basetype):
+        self.type = basetype
+
+    def isScriptable(self):
+        return self.type.isScriptable()
+
+    def nativeType(self, calltype, const=False):
+        return "%s%s*" % (const and 'const ' or '',
+                          self.type.nativeType(calltype))
+
+
+class IDLParser(object):
+    keywords = {
+        'const': 'CONST',
+        'interface': 'INTERFACE',
+        'in': 'IN',
+        'inout': 'INOUT',
+        'out': 'OUT',
+        'attribute': 'ATTRIBUTE',
+        'raises': 'RAISES',
+        'readonly': 'READONLY',
+        'native': 'NATIVE',
+        'typedef': 'TYPEDEF',
+        }
+
+    tokens = [
+        'IDENTIFIER',
+        'CDATA',
+        'INCLUDE',
+        'IID',
+        'NUMBER',
+        'HEXNUM',
+        'LSHIFT',
+        'RSHIFT',
+        'NATIVEID',
+        ]
+
+    tokens.extend(keywords.values())
+
+    states = (
+        ('nativeid', 'exclusive'),
+    )
+
+    hexchar = r'[a-fA-F0-9]'
+
+    t_NUMBER = r'-?\d+'
+    t_HEXNUM = r'0x%s+' % hexchar
+    t_LSHIFT = r'<<'
+    t_RSHIFT = r'>>'
+
+    literals = '"(){}[],;:=|+-*'
+
+    t_ignore = ' \t'
+
+    def t_multilinecomment(self, t):
+        r'/\*(?s).*?\*/'
+        t.lexer.lineno += t.value.count('\n')
+        if t.value.startswith("/**"):
+            self._doccomments.append(t.value)
+
+    def t_singlelinecomment(self, t):
+        r'(?m)//.*?$'
+
+    def t_IID(self, t):
+        return t
+    t_IID.__doc__ = r'%(c)s{8}-%(c)s{4}-%(c)s{4}-%(c)s{4}-%(c)s{12}' % {'c': hexchar}
+
+    def t_IDENTIFIER(self, t):
+        r'(unsigned\ long\ long|unsigned\ short|unsigned\ long|long\ long)(?!_?[A-Za-z][A-Za-z_0-9])|_?[A-Za-z][A-Za-z_0-9]*'
+        t.type = self.keywords.get(t.value, 'IDENTIFIER')
+        return t
+
+    def t_LCDATA(self, t):
+        r'(?s)%\{[ ]*C\+\+[ ]*\n(?P<cdata>.*?\n?)%\}[ ]*(C\+\+)?'
+        t.type = 'CDATA'
+        t.value = t.lexer.lexmatch.group('cdata')
+        t.lexer.lineno += t.value.count('\n')
+        return t
+
+    def t_INCLUDE(self, t):
+        r'\#include[ \t]+"[^"\n]+"'
+        inc, value, end = t.value.split('"')
+        t.value = value
+        return t
+
+    def t_directive(self, t):
+        r'\#(?P<directive>[a-zA-Z]+)[^\n]+'
+        raise IDLError("Unrecognized directive %s" % t.lexer.lexmatch.group('directive'),
+                       Location(lexer=self.lexer, lineno=self.lexer.lineno,
+                                lexpos=self.lexer.lexpos))
+
+    def t_newline(self, t):
+        r'\n+'
+        t.lexer.lineno += len(t.value)
+
+    def t_nativeid_NATIVEID(self, t):
+        r'[^()\n]+(?=\))'
+        t.lexer.begin('INITIAL')
+        return t
+
+    t_nativeid_ignore = ''
+
+    def t_ANY_error(self, t):
+        raise IDLError("unrecognized input",
+                       Location(lexer=self.lexer,
+                                lineno=self.lexer.lineno,
+                                lexpos=self.lexer.lexpos))
+
+    precedence = (
+        ('left', '|'),
+        ('left', 'LSHIFT', 'RSHIFT'),
+        ('left', '+', '-'),
+        ('left', '*'),
+        ('left', 'UMINUS'),
+    )
+
+    def p_idlfile(self, p):
+        """idlfile : productions"""
+        p[0] = IDL(p[1])
+
+    def p_productions_start(self, p):
+        """productions : """
+        p[0] = []
+
+    def p_productions_cdata(self, p):
+        """productions : CDATA productions"""
+        p[0] = list(p[2])
+        p[0].insert(0, CDATA(p[1], self.getLocation(p, 1)))
+
+    def p_productions_include(self, p):
+        """productions : INCLUDE productions"""
+        p[0] = list(p[2])
+        p[0].insert(0, Include(p[1], self.getLocation(p, 1)))
+
+    def p_productions_interface(self, p):
+        """productions : interface productions
+                       | typedef productions
+                       | native productions"""
+        p[0] = list(p[2])
+        p[0].insert(0, p[1])
+
+    def p_typedef(self, p):
+        """typedef : TYPEDEF IDENTIFIER IDENTIFIER ';'"""
+        p[0] = Typedef(type=p[2],
+                       name=p[3],
+                       location=self.getLocation(p, 1),
+                       doccomments=p.slice[1].doccomments)
+
+    def p_native(self, p):
+        """native : attributes NATIVE IDENTIFIER afternativeid '(' NATIVEID ')' ';'"""
+        p[0] = Native(name=p[3],
+                      nativename=p[6],
+                      attlist=p[1]['attlist'],
+                      location=self.getLocation(p, 2))
+
+    def p_afternativeid(self, p):
+        """afternativeid : """
+        # this is a place marker: we switch the lexer into literal identifier
+        # mode here, to slurp up everything until the closeparen
+        self.lexer.begin('nativeid')
+
+    def p_anyident(self, p):
+        """anyident : IDENTIFIER
+                    | CONST"""
+        p[0] = {'value': p[1],
+                'location': self.getLocation(p, 1)}
+
+    def p_attributes(self, p):
+        """attributes : '[' attlist ']'
+                      | """
+        if len(p) == 1:
+            p[0] = {'attlist': []}
+        else:
+            p[0] = {'attlist': p[2],
+                    'doccomments': p.slice[1].doccomments}
+
+    def p_attlist_start(self, p):
+        """attlist : attribute"""
+        p[0] = [p[1]]
+
+    def p_attlist_continue(self, p):
+        """attlist : attribute ',' attlist"""
+        p[0] = list(p[3])
+        p[0].insert(0, p[1])
+
+    def p_attribute(self, p):
+        """attribute : anyident attributeval"""
+        p[0] = (p[1]['value'], p[2], p[1]['location'])
+
+    def p_attributeval(self, p):
+        """attributeval : '(' IDENTIFIER ')'
+                        | '(' IID ')'
+                        | """
+        if len(p) > 1:
+            p[0] = p[2]
+
+    def p_interface(self, p):
+        """interface : attributes INTERFACE IDENTIFIER ifacebase ifacebody ';'"""
+        atts, INTERFACE, name, base, body, SEMI = p[1:]
+        attlist = atts['attlist']
+        doccomments = []
+        if 'doccomments' in atts:
+            doccomments.extend(atts['doccomments'])
+        doccomments.extend(p.slice[2].doccomments)
+
+        l = lambda: self.getLocation(p, 2)
+
+        if body is None:
+            # forward-declared interface... must not have attributes!
+            if len(attlist) != 0:
+                raise IDLError("Forward-declared interface must not have attributes",
+                               list[0][3])
+
+            if base is not None:
+                raise IDLError("Forward-declared interface must not have a base",
+                               l())
+            p[0] = Forward(name=name, location=l(), doccomments=doccomments)
+        else:
+            p[0] = Interface(name=name,
+                             attlist=attlist,
+                             base=base,
+                             members=body,
+                             location=l(),
+                             doccomments=doccomments)
+
+    def p_ifacebody(self, p):
+        """ifacebody : '{' members '}'
+                     | """
+        if len(p) > 1:
+            p[0] = p[2]
+
+    def p_ifacebase(self, p):
+        """ifacebase : ':' IDENTIFIER
+                     | """
+        if len(p) == 3:
+            p[0] = p[2]
+
+    def p_members_start(self, p):
+        """members : """
+        p[0] = []
+
+    def p_members_continue(self, p):
+        """members : member members"""
+        p[0] = list(p[2])
+        p[0].insert(0, p[1])
+
+    def p_member_cdata(self, p):
+        """member : CDATA"""
+        p[0] = CDATA(p[1], self.getLocation(p, 1))
+
+    def p_member_const(self, p):
+        """member : CONST IDENTIFIER IDENTIFIER '=' number ';' """
+        p[0] = ConstMember(type=p[2], name=p[3],
+                           value=p[5], location=self.getLocation(p, 1),
+                           doccomments=p.slice[1].doccomments)
+
+# All "number" products return a function(interface)
+
+    def p_number_decimal(self, p):
+        """number : NUMBER"""
+        n = int(p[1])
+        p[0] = lambda i: n
+
+    def p_number_hex(self, p):
+        """number : HEXNUM"""
+        n = int(p[1], 16)
+        p[0] = lambda i: n
+
+    def p_number_identifier(self, p):
+        """number : IDENTIFIER"""
+        id = p[1]
+        loc = self.getLocation(p, 1)
+        p[0] = lambda i: i.getConst(id, loc)
+
+    def p_number_paren(self, p):
+        """number : '(' number ')'"""
+        p[0] = p[2]
+
+    def p_number_neg(self, p):
+        """number : '-' number %prec UMINUS"""
+        n = p[2]
+        p[0] = lambda i: - n(i)
+
+    def p_number_add(self, p):
+        """number : number '+' number
+                  | number '-' number
+                  | number '*' number"""
+        n1 = p[1]
+        n2 = p[3]
+        if p[2] == '+':
+            p[0] = lambda i: n1(i) + n2(i)
+        elif p[2] == '-':
+            p[0] = lambda i: n1(i) - n2(i)
+        else:
+            p[0] = lambda i: n1(i) * n2(i)
+
+    def p_number_shift(self, p):
+        """number : number LSHIFT number
+                  | number RSHIFT number"""
+        n1 = p[1]
+        n2 = p[3]
+        if p[2] == '<<':
+            p[0] = lambda i: n1(i) << n2(i)
+        else:
+            p[0] = lambda i: n1(i) >> n2(i)
+
+    def p_number_bitor(self, p):
+        """number : number '|' number"""
+        n1 = p[1]
+        n2 = p[3]
+        p[0] = lambda i: n1(i) | n2(i)
+
+    def p_member_att(self, p):
+        """member : attributes optreadonly ATTRIBUTE IDENTIFIER IDENTIFIER ';'"""
+        if 'doccomments' in p[1]:
+            doccomments = p[1]['doccomments']
+        elif p[2] is not None:
+            doccomments = p[2]
+        else:
+            doccomments = p.slice[3].doccomments
+
+        p[0] = Attribute(type=p[4],
+                         name=p[5],
+                         attlist=p[1]['attlist'],
+                         readonly=p[2] is not None,
+                         location=self.getLocation(p, 3),
+                         doccomments=doccomments)
+
+    def p_member_method(self, p):
+        """member : attributes IDENTIFIER IDENTIFIER '(' paramlist ')' raises ';'"""
+        if 'doccomments' in p[1]:
+            doccomments = p[1]['doccomments']
+        else:
+            doccomments = p.slice[2].doccomments
+
+        p[0] = Method(type=p[2],
+                      name=p[3],
+                      attlist=p[1]['attlist'],
+                      paramlist=p[5],
+                      location=self.getLocation(p, 3),
+                      doccomments=doccomments,
+                      raises=p[7])
+
+    def p_paramlist(self, p):
+        """paramlist : param moreparams
+                     | """
+        if len(p) == 1:
+            p[0] = []
+        else:
+            p[0] = list(p[2])
+            p[0].insert(0, p[1])
+
+    def p_moreparams_start(self, p):
+        """moreparams :"""
+        p[0] = []
+
+    def p_moreparams_continue(self, p):
+        """moreparams : ',' param moreparams"""
+        p[0] = list(p[3])
+        p[0].insert(0, p[2])
+
+    def p_param(self, p):
+        """param : attributes paramtype IDENTIFIER IDENTIFIER"""
+        p[0] = Param(paramtype=p[2],
+                     type=p[3],
+                     name=p[4],
+                     attlist=p[1]['attlist'],
+                     location=self.getLocation(p, 3))
+
+    def p_paramtype(self, p):
+        """paramtype : IN
+                     | INOUT
+                     | OUT"""
+        p[0] = p[1]
+
+    def p_optreadonly(self, p):
+        """optreadonly : READONLY
+                       | """
+        if len(p) > 1:
+            p[0] = p.slice[1].doccomments
+        else:
+            p[0] = None
+
+    def p_raises(self, p):
+        """raises : RAISES '(' idlist ')'
+                  | """
+        if len(p) == 1:
+            p[0] = []
+        else:
+            p[0] = p[3]
+
+    def p_idlist(self, p):
+        """idlist : IDENTIFIER"""
+        p[0] = [p[1]]
+
+    def p_idlist_continue(self, p):
+        """idlist : IDENTIFIER ',' idlist"""
+        p[0] = list(p[3])
+        p[0].insert(0, p[1])
+
+    def p_error(self, t):
+        if not t:
+            raise IDLError("Syntax Error at end of file. Possibly due to missing semicolon(;), braces(}) or both", None)
+        else:
+            location = Location(self.lexer, t.lineno, t.lexpos)
+            raise IDLError("invalid syntax", location)
+
+    def __init__(self, outputdir=''):
+        self._doccomments = []
+        self.lexer = lex.lex(object=self,
+                             outputdir=outputdir,
+                             lextab='xpidllex',
+                             optimize=1)
+        self.parser = yacc.yacc(module=self,
+                                outputdir=outputdir,
+                                debug=0,
+                                tabmodule='xpidlyacc',
+                                optimize=1)
+
+    def clearComments(self):
+        self._doccomments = []
+
+    def token(self):
+        t = self.lexer.token()
+        if t is not None and t.type != 'CDATA':
+            t.doccomments = self._doccomments
+            self._doccomments = []
+        return t
+
+    def parse(self, data, filename=None):
+        if filename is not None:
+            self.lexer.filename = filename
+        self.lexer.lineno = 1
+        self.lexer.input(data)
+        idl = self.parser.parse(lexer=self)
+        if filename is not None:
+            idl.deps.append(filename)
+        return idl
+
+    def getLocation(self, p, i):
+        return Location(self.lexer, p.lineno(i), p.lexpos(i))
+
+if __name__ == '__main__':
+    p = IDLParser()
+    for f in sys.argv[1:]:
+        print "Parsing %s" % f
+        p.parse(open(f).read(), filename=f)
diff --git a/xpcom/io/Base64.cpp b/xpcom/io/Base64.cpp
new file mode 100644
index 000000000..911c0595a
--- /dev/null
+++ b/xpcom/io/Base64.cpp
@@ -0,0 +1,645 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "Base64.h"
+
+#include "mozilla/UniquePtrExtensions.h"
+#include "nsIInputStream.h"
+#include "nsString.h"
+#include "nsTArray.h"
+
+#include "plbase64.h"
+
+namespace {
+
+// BEGIN base64 encode code copied and modified from NSPR
+const unsigned char* base =
+  (unsigned char*)"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+                  "abcdefghijklmnopqrstuvwxyz"
+                  "0123456789+/";
+
+template<typename T>
+static void
+Encode3to4(const unsigned char* aSrc, T* aDest)
+{
+  uint32_t b32 = (uint32_t)0;
+  int i, j = 18;
+
+  for (i = 0; i < 3; ++i) {
+    b32 <<= 8;
+    b32 |= (uint32_t)aSrc[i];
+  }
+
+  for (i = 0; i < 4; ++i) {
+    aDest[i] = base[(uint32_t)((b32 >> j) & 0x3F)];
+    j -= 6;
+  }
+}
+
+template<typename T>
+static void
+Encode2to4(const unsigned char* aSrc, T* aDest)
+{
+  aDest[0] = base[(uint32_t)((aSrc[0] >> 2) & 0x3F)];
+  aDest[1] = base[(uint32_t)(((aSrc[0] & 0x03) << 4) | ((aSrc[1] >> 4) & 0x0F))];
+  aDest[2] = base[(uint32_t)((aSrc[1] & 0x0F) << 2)];
+  aDest[3] = (unsigned char)'=';
+}
+
+template<typename T>
+static void
+Encode1to4(const unsigned char* aSrc, T* aDest)
+{
+  aDest[0] = base[(uint32_t)((aSrc[0] >> 2) & 0x3F)];
+  aDest[1] = base[(uint32_t)((aSrc[0] & 0x03) << 4)];
+  aDest[2] = (unsigned char)'=';
+  aDest[3] = (unsigned char)'=';
+}
+
+template<typename T>
+static void
+Encode(const unsigned char* aSrc, uint32_t aSrcLen, T* aDest)
+{
+  while (aSrcLen >= 3) {
+    Encode3to4(aSrc, aDest);
+    aSrc += 3;
+    aDest += 4;
+    aSrcLen -= 3;
+  }
+
+  switch (aSrcLen) {
+    case 2:
+      Encode2to4(aSrc, aDest);
+      break;
+    case 1:
+      Encode1to4(aSrc, aDest);
+      break;
+    case 0:
+      break;
+    default:
+      NS_NOTREACHED("coding error");
+  }
+}
+
+// END base64 encode code copied and modified from NSPR.
+
+template<typename T>
+struct EncodeInputStream_State
+{
+  unsigned char c[3];
+  uint8_t charsOnStack;
+  typename T::char_type* buffer;
+};
+
+template<typename T>
+nsresult
+EncodeInputStream_Encoder(nsIInputStream* aStream,
+                          void* aClosure,
+                          const char* aFromSegment,
+                          uint32_t aToOffset,
+                          uint32_t aCount,
+                          uint32_t* aWriteCount)
+{
+  NS_ASSERTION(aCount > 0, "Er, what?");
+
+  EncodeInputStream_State<T>* state =
+    static_cast<EncodeInputStream_State<T>*>(aClosure);
+
+  // If we have any data left from last time, encode it now.
+  uint32_t countRemaining = aCount;
+  const unsigned char* src = (const unsigned char*)aFromSegment;
+  if (state->charsOnStack) {
+    unsigned char firstSet[4];
+    if (state->charsOnStack == 1) {
+      firstSet[0] = state->c[0];
+      firstSet[1] = src[0];
+      firstSet[2] = (countRemaining > 1) ? src[1] : '\0';
+      firstSet[3] = '\0';
+    } else /* state->charsOnStack == 2 */ {
+      firstSet[0] = state->c[0];
+      firstSet[1] = state->c[1];
+      firstSet[2] = src[0];
+      firstSet[3] = '\0';
+    }
+    Encode(firstSet, 3, state->buffer);
+    state->buffer += 4;
+    countRemaining -= (3 - state->charsOnStack);
+    src += (3 - state->charsOnStack);
+    state->charsOnStack = 0;
+  }
+
+  // Encode the bulk of the
+  uint32_t encodeLength = countRemaining - countRemaining % 3;
+  MOZ_ASSERT(encodeLength % 3 == 0,
+             "Should have an exact number of triplets!");
+  Encode(src, encodeLength, state->buffer);
+  state->buffer += (encodeLength / 3) * 4;
+  src += encodeLength;
+  countRemaining -= encodeLength;
+
+  // We must consume all data, so if there's some data left stash it
+  *aWriteCount = aCount;
+
+  if (countRemaining) {
+    // We should never have a full triplet left at this point.
+    MOZ_ASSERT(countRemaining < 3, "We should have encoded more!");
+    state->c[0] = src[0];
+    state->c[1] = (countRemaining == 2) ? src[1] : '\0';
+    state->charsOnStack = countRemaining;
+  }
+
+  return NS_OK;
+}
+
+template<typename T>
+nsresult
+EncodeInputStream(nsIInputStream* aInputStream,
+                  T& aDest,
+                  uint32_t aCount,
+                  uint32_t aOffset)
+{
+  nsresult rv;
+  uint64_t count64 = aCount;
+
+  if (!aCount) {
+    rv = aInputStream->Available(&count64);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+    // if count64 is over 4GB, it will be failed at the below condition,
+    // then will return NS_ERROR_OUT_OF_MEMORY
+    aCount = (uint32_t)count64;
+  }
+
+  uint64_t countlong =
+    (count64 + 2) / 3 * 4; // +2 due to integer math.
+  if (countlong + aOffset > UINT32_MAX) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  uint32_t count = uint32_t(countlong);
+
+  if (!aDest.SetLength(count + aOffset, mozilla::fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  EncodeInputStream_State<T> state;
+  state.charsOnStack = 0;
+  state.c[2] = '\0';
+  state.buffer = aOffset + aDest.BeginWriting();
+
+  while (1) {
+    uint32_t read = 0;
+
+    rv = aInputStream->ReadSegments(&EncodeInputStream_Encoder<T>,
+                                    (void*)&state,
+                                    aCount,
+                                    &read);
+    if (NS_FAILED(rv)) {
+      if (rv == NS_BASE_STREAM_WOULD_BLOCK) {
+        NS_RUNTIMEABORT("Not implemented for async streams!");
+      }
+      if (rv == NS_ERROR_NOT_IMPLEMENTED) {
+        NS_RUNTIMEABORT("Requires a stream that implements ReadSegments!");
+      }
+      return rv;
+    }
+
+    if (!read) {
+      break;
+    }
+  }
+
+  // Finish encoding if anything is left
+  if (state.charsOnStack) {
+    Encode(state.c, state.charsOnStack, state.buffer);
+  }
+
+  if (aDest.Length()) {
+    // May belong to an nsCString with an unallocated buffer, so only null
+    // terminate if there is a need to.
+    *aDest.EndWriting() = '\0';
+  }
+
+  return NS_OK;
+}
+
+static const char kBase64URLAlphabet[] =
+  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
+
+// Maps an encoded character to a value in the Base64 URL alphabet, per
+// RFC 4648, Table 2. Invalid input characters map to UINT8_MAX.
+static const uint8_t kBase64URLDecodeTable[] = {
+  255, 255, 255, 255, 255, 255, 255, 255,
+  255, 255, 255, 255, 255, 255, 255, 255,
+  255, 255, 255, 255, 255, 255, 255, 255,
+  255, 255, 255, 255, 255, 255, 255, 255,
+  255, 255, 255, 255, 255, 255, 255, 255,
+  255, 255, 255, 255, 255,
+  62 /* - */,
+  255, 255,
+  52, 53, 54, 55, 56, 57, 58, 59, 60, 61, /* 0 - 9 */
+  255, 255, 255, 255, 255, 255, 255,
+  0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
+  16, 17, 18, 19, 20, 21, 22, 23, 24, 25, /* A - Z */
+  255, 255, 255, 255,
+  63 /* _ */,
+  255,
+  26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41,
+  42, 43, 44, 45, 46, 47, 48, 49, 50, 51, /* a - z */
+  255, 255, 255, 255,
+};
+
+bool
+Base64URLCharToValue(char aChar, uint8_t* aValue) {
+  uint8_t index = static_cast<uint8_t>(aChar);
+  *aValue = kBase64URLDecodeTable[index & 0x7f];
+  return (*aValue != 255) && !(index & ~0x7f);
+}
+
+} // namespace
+
+namespace mozilla {
+
+nsresult
+Base64EncodeInputStream(nsIInputStream* aInputStream,
+                        nsACString& aDest,
+                        uint32_t aCount,
+                        uint32_t aOffset)
+{
+  return EncodeInputStream<nsACString>(aInputStream, aDest, aCount, aOffset);
+}
+
+nsresult
+Base64EncodeInputStream(nsIInputStream* aInputStream,
+                        nsAString& aDest,
+                        uint32_t aCount,
+                        uint32_t aOffset)
+{
+  return EncodeInputStream<nsAString>(aInputStream, aDest, aCount, aOffset);
+}
+
+nsresult
+Base64Encode(const char* aBinary, uint32_t aBinaryLen, char** aBase64)
+{
+  // Check for overflow.
+  if (aBinaryLen > (UINT32_MAX / 4) * 3) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Don't ask PR_Base64Encode to encode empty strings.
+  if (aBinaryLen == 0) {
+    *aBase64 = (char*)moz_xmalloc(1);
+    (*aBase64)[0] = '\0';
+    return NS_OK;
+  }
+
+  *aBase64 = nullptr;
+  uint32_t base64Len = ((aBinaryLen + 2) / 3) * 4;
+
+  // Add one byte for null termination.
+  UniqueFreePtr<char[]> base64((char*)malloc(base64Len + 1));
+  if (!base64) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  if (!PL_Base64Encode(aBinary, aBinaryLen, base64.get())) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // PL_Base64Encode doesn't null terminate the buffer for us when we pass
+  // the buffer in. Do that manually.
+  base64[base64Len] = '\0';
+
+  *aBase64 = base64.release();
+  return NS_OK;
+}
+
+nsresult
+Base64Encode(const nsACString& aBinary, nsACString& aBase64)
+{
+  // Check for overflow.
+  if (aBinary.Length() > (UINT32_MAX / 4) * 3) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Don't ask PR_Base64Encode to encode empty strings.
+  if (aBinary.IsEmpty()) {
+    aBase64.Truncate();
+    return NS_OK;
+  }
+
+  uint32_t base64Len = ((aBinary.Length() + 2) / 3) * 4;
+
+  // Add one byte for null termination.
+  if (!aBase64.SetCapacity(base64Len + 1, fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  char* base64 = aBase64.BeginWriting();
+  if (!PL_Base64Encode(aBinary.BeginReading(), aBinary.Length(), base64)) {
+    aBase64.Truncate();
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // PL_Base64Encode doesn't null terminate the buffer for us when we pass
+  // the buffer in. Do that manually.
+  base64[base64Len] = '\0';
+
+  aBase64.SetLength(base64Len);
+  return NS_OK;
+}
+
+nsresult
+Base64Encode(const nsAString& aBinary, nsAString& aBase64)
+{
+  NS_LossyConvertUTF16toASCII binary(aBinary);
+  nsAutoCString base64;
+
+  nsresult rv = Base64Encode(binary, base64);
+  if (NS_SUCCEEDED(rv)) {
+    CopyASCIItoUTF16(base64, aBase64);
+  } else {
+    aBase64.Truncate();
+  }
+
+  return rv;
+}
+
+static nsresult
+Base64DecodeHelper(const char* aBase64, uint32_t aBase64Len, char* aBinary,
+                   uint32_t* aBinaryLen)
+{
+  MOZ_ASSERT(aBinary);
+  if (!PL_Base64Decode(aBase64, aBase64Len, aBinary)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // PL_Base64Decode doesn't null terminate the buffer for us when we pass
+  // the buffer in. Do that manually, taking into account the number of '='
+  // characters we were passed.
+  if (aBase64Len != 0 && aBase64[aBase64Len - 1] == '=') {
+    if (aBase64Len > 1 && aBase64[aBase64Len - 2] == '=') {
+      *aBinaryLen -= 2;
+    } else {
+      *aBinaryLen -= 1;
+    }
+  }
+  aBinary[*aBinaryLen] = '\0';
+  return NS_OK;
+}
+
+nsresult
+Base64Decode(const char* aBase64, uint32_t aBase64Len, char** aBinary,
+             uint32_t* aBinaryLen)
+{
+  // Check for overflow.
+  if (aBase64Len > UINT32_MAX / 3) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Don't ask PR_Base64Decode to decode the empty string.
+  if (aBase64Len == 0) {
+    *aBinary = (char*)moz_xmalloc(1);
+    (*aBinary)[0] = '\0';
+    *aBinaryLen = 0;
+    return NS_OK;
+  }
+
+  *aBinary = nullptr;
+  *aBinaryLen = (aBase64Len * 3) / 4;
+
+  // Add one byte for null termination.
+  UniqueFreePtr<char[]> binary((char*)malloc(*aBinaryLen + 1));
+  if (!binary) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  nsresult rv =
+    Base64DecodeHelper(aBase64, aBase64Len, binary.get(), aBinaryLen);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  *aBinary = binary.release();
+  return NS_OK;
+}
+
+nsresult
+Base64Decode(const nsACString& aBase64, nsACString& aBinary)
+{
+  // Check for overflow.
+  if (aBase64.Length() > UINT32_MAX / 3) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Don't ask PR_Base64Decode to decode the empty string
+  if (aBase64.IsEmpty()) {
+    aBinary.Truncate();
+    return NS_OK;
+  }
+
+  uint32_t binaryLen = ((aBase64.Length() * 3) / 4);
+
+  // Add one byte for null termination.
+  if (!aBinary.SetCapacity(binaryLen + 1, fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  char* binary = aBinary.BeginWriting();
+  nsresult rv = Base64DecodeHelper(aBase64.BeginReading(), aBase64.Length(),
+                                   binary, &binaryLen);
+  if (NS_FAILED(rv)) {
+    aBinary.Truncate();
+    return rv;
+  }
+
+  aBinary.SetLength(binaryLen);
+  return NS_OK;
+}
+
+nsresult
+Base64Decode(const nsAString& aBase64, nsAString& aBinary)
+{
+  NS_LossyConvertUTF16toASCII base64(aBase64);
+  nsAutoCString binary;
+
+  nsresult rv = Base64Decode(base64, binary);
+  if (NS_SUCCEEDED(rv)) {
+    CopyASCIItoUTF16(binary, aBinary);
+  } else {
+    aBinary.Truncate();
+  }
+
+  return rv;
+}
+
+nsresult
+Base64URLDecode(const nsACString& aBase64,
+                Base64URLDecodePaddingPolicy aPaddingPolicy,
+                FallibleTArray<uint8_t>& aBinary)
+{
+  // Don't decode empty strings.
+  if (aBase64.IsEmpty()) {
+    aBinary.Clear();
+    return NS_OK;
+  }
+
+  // Check for overflow.
+  uint32_t base64Len = aBase64.Length();
+  if (base64Len > UINT32_MAX / 3) {
+    return NS_ERROR_FAILURE;
+  }
+  const char* base64 = aBase64.BeginReading();
+
+  // The decoded length may be 1-2 bytes over, depending on the final quantum.
+  uint32_t binaryLen = (base64Len * 3) / 4;
+
+  // Determine whether to check for and ignore trailing padding.
+  bool maybePadded = false;
+  switch (aPaddingPolicy) {
+    case Base64URLDecodePaddingPolicy::Require:
+      if (base64Len % 4) {
+        // Padded input length must be a multiple of 4.
+        return NS_ERROR_INVALID_ARG;
+      }
+      maybePadded = true;
+      break;
+
+    case Base64URLDecodePaddingPolicy::Ignore:
+      // Check for padding only if the length is a multiple of 4.
+      maybePadded = !(base64Len % 4);
+      break;
+
+    // If we're expecting unpadded input, no need for additional checks.
+    // `=` isn't in the decode table, so padded strings will fail to decode.
+    default:
+      MOZ_FALLTHROUGH_ASSERT("Invalid decode padding policy");
+    case Base64URLDecodePaddingPolicy::Reject:
+      break;
+  }
+  if (maybePadded && base64[base64Len - 1] == '=') {
+    if (base64[base64Len - 2] == '=') {
+      base64Len -= 2;
+    } else {
+      base64Len -= 1;
+    }
+  }
+
+  if (NS_WARN_IF(!aBinary.SetCapacity(binaryLen, mozilla::fallible))) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  aBinary.SetLengthAndRetainStorage(binaryLen);
+  uint8_t* binary = aBinary.Elements();
+
+  for (; base64Len >= 4; base64Len -= 4) {
+    uint8_t w, x, y, z;
+    if (!Base64URLCharToValue(*base64++, &w) ||
+        !Base64URLCharToValue(*base64++, &x) ||
+        !Base64URLCharToValue(*base64++, &y) ||
+        !Base64URLCharToValue(*base64++, &z)) {
+      return NS_ERROR_INVALID_ARG;
+    }
+    *binary++ = w << 2 | x >> 4;
+    *binary++ = x << 4 | y >> 2;
+    *binary++ = y << 6 | z;
+  }
+
+  if (base64Len == 3) {
+    uint8_t w, x, y;
+    if (!Base64URLCharToValue(*base64++, &w) ||
+        !Base64URLCharToValue(*base64++, &x) ||
+        !Base64URLCharToValue(*base64++, &y)) {
+      return NS_ERROR_INVALID_ARG;
+    }
+    *binary++ = w << 2 | x >> 4;
+    *binary++ = x << 4 | y >> 2;
+  } else if (base64Len == 2) {
+    uint8_t w, x;
+    if (!Base64URLCharToValue(*base64++, &w) ||
+        !Base64URLCharToValue(*base64++, &x)) {
+      return NS_ERROR_INVALID_ARG;
+    }
+    *binary++ = w << 2 | x >> 4;
+  } else if (base64Len) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // Set the length to the actual number of decoded bytes.
+  aBinary.TruncateLength(binary - aBinary.Elements());
+  return NS_OK;
+}
+
+nsresult
+Base64URLEncode(uint32_t aBinaryLen, const uint8_t* aBinary,
+                Base64URLEncodePaddingPolicy aPaddingPolicy,
+                nsACString& aBase64)
+{
+  // Don't encode empty strings.
+  if (aBinaryLen == 0) {
+    aBase64.Truncate();
+    return NS_OK;
+  }
+
+  // Check for overflow.
+  if (aBinaryLen > (UINT32_MAX / 4) * 3) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Allocate a buffer large enough to hold the encoded string with padding.
+  // Add one byte for null termination.
+  uint32_t base64Len = ((aBinaryLen + 2) / 3) * 4;
+  if (NS_WARN_IF(!aBase64.SetCapacity(base64Len + 1, fallible))) {
+    aBase64.Truncate();
+    return NS_ERROR_FAILURE;
+  }
+
+  char* base64 = aBase64.BeginWriting();
+
+  uint32_t index = 0;
+  for (; index + 3 <= aBinaryLen; index += 3) {
+    *base64++ = kBase64URLAlphabet[aBinary[index] >> 2];
+    *base64++ = kBase64URLAlphabet[((aBinary[index] & 0x3) << 4) |
+                                   (aBinary[index + 1] >> 4)];
+    *base64++ = kBase64URLAlphabet[((aBinary[index + 1] & 0xf) << 2) |
+                                   (aBinary[index + 2] >> 6)];
+    *base64++ = kBase64URLAlphabet[aBinary[index + 2] & 0x3f];
+  }
+
+  uint32_t remaining = aBinaryLen - index;
+  if (remaining == 1) {
+    *base64++ = kBase64URLAlphabet[aBinary[index] >> 2];
+    *base64++ = kBase64URLAlphabet[((aBinary[index] & 0x3) << 4)];
+  } else if (remaining == 2) {
+    *base64++ = kBase64URLAlphabet[aBinary[index] >> 2];
+    *base64++ = kBase64URLAlphabet[((aBinary[index] & 0x3) << 4) |
+                                   (aBinary[index + 1] >> 4)];
+    *base64++ = kBase64URLAlphabet[((aBinary[index + 1] & 0xf) << 2)];
+  }
+
+  uint32_t length = base64 - aBase64.BeginWriting();
+  if (aPaddingPolicy == Base64URLEncodePaddingPolicy::Include) {
+    if (length % 4 == 2) {
+      *base64++ = '=';
+      *base64++ = '=';
+      length += 2;
+    } else if (length % 4 == 3) {
+      *base64++ = '=';
+      length += 1;
+    }
+  } else {
+    MOZ_ASSERT(aPaddingPolicy == Base64URLEncodePaddingPolicy::Omit,
+               "Invalid encode padding policy");
+  }
+
+  // Null terminate and truncate to the actual number of characters.
+  *base64 = '\0';
+  aBase64.SetLength(length);
+
+  return NS_OK;
+}
+
+} // namespace mozilla
diff --git a/xpcom/io/Base64.h b/xpcom/io/Base64.h
new file mode 100644
index 000000000..0c3f1e140
--- /dev/null
+++ b/xpcom/io/Base64.h
@@ -0,0 +1,73 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_Base64_h__
+#define mozilla_Base64_h__
+
+#include "nsString.h"
+
+class nsIInputStream;
+
+namespace mozilla {
+
+MOZ_MUST_USE nsresult
+Base64EncodeInputStream(nsIInputStream* aInputStream,
+                        nsACString& aDest,
+                        uint32_t aCount,
+                        uint32_t aOffset = 0);
+MOZ_MUST_USE nsresult
+Base64EncodeInputStream(nsIInputStream* aInputStream,
+                        nsAString& aDest,
+                        uint32_t aCount,
+                        uint32_t aOffset = 0);
+
+MOZ_MUST_USE nsresult
+Base64Encode(const char* aBinary, uint32_t aBinaryLen, char** aBase64);
+MOZ_MUST_USE nsresult
+Base64Encode(const nsACString& aBinary, nsACString& aBase64);
+MOZ_MUST_USE nsresult
+Base64Encode(const nsAString& aBinary, nsAString& aBase64);
+
+MOZ_MUST_USE nsresult
+Base64Decode(const char* aBase64, uint32_t aBase64Len, char** aBinary,
+             uint32_t* aBinaryLen);
+MOZ_MUST_USE nsresult
+Base64Decode(const nsACString& aBase64, nsACString& aBinary);
+MOZ_MUST_USE nsresult
+Base64Decode(const nsAString& aBase64, nsAString& aBinary);
+
+enum class Base64URLEncodePaddingPolicy {
+  Include,
+  Omit,
+};
+
+/**
+ * Converts |aBinary| to an unpadded, Base64 URL-encoded string per RFC 4648.
+ * Aims to encode the data in constant time. The caller retains ownership
+ * of |aBinary|.
+ */
+MOZ_MUST_USE nsresult
+Base64URLEncode(uint32_t aBinaryLen, const uint8_t* aBinary,
+                Base64URLEncodePaddingPolicy aPaddingPolicy,
+                nsACString& aBase64);
+
+enum class Base64URLDecodePaddingPolicy {
+  Require,
+  Ignore,
+  Reject,
+};
+
+/**
+ * Decodes a Base64 URL-encoded |aBase64| into |aBinary|.
+ */
+MOZ_MUST_USE nsresult
+Base64URLDecode(const nsACString& aBase64,
+                Base64URLDecodePaddingPolicy aPaddingPolicy,
+                FallibleTArray<uint8_t>& aBinary);
+
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/io/CocoaFileUtils.h b/xpcom/io/CocoaFileUtils.h
new file mode 100644
index 000000000..7127cb65d
--- /dev/null
+++ b/xpcom/io/CocoaFileUtils.h
@@ -0,0 +1,35 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// This namespace contains methods with Obj-C/Cocoa implementations. The header
+// is C/C++ for inclusion in C/C++-only files.
+
+#ifndef CocoaFileUtils_h_
+#define CocoaFileUtils_h_
+
+#include "nscore.h"
+#include <CoreFoundation/CoreFoundation.h>
+
+namespace CocoaFileUtils {
+
+nsresult RevealFileInFinder(CFURLRef aUrl);
+nsresult OpenURL(CFURLRef aUrl);
+nsresult GetFileCreatorCode(CFURLRef aUrl, OSType* aCreatorCode);
+nsresult SetFileCreatorCode(CFURLRef aUrl, OSType aCreatorCode);
+nsresult GetFileTypeCode(CFURLRef aUrl, OSType* aTypeCode);
+nsresult SetFileTypeCode(CFURLRef aUrl, OSType aTypeCode);
+void     AddOriginMetadataToFile(const CFStringRef filePath,
+                                 const CFURLRef sourceURL,
+                                 const CFURLRef referrerURL);
+void     AddQuarantineMetadataToFile(const CFStringRef filePath,
+                                     const CFURLRef sourceURL,
+                                     const CFURLRef referrerURL,
+                                     const bool isFromWeb);
+CFURLRef GetTemporaryFolderCFURLRef();
+
+} // namespace CocoaFileUtils
+
+#endif
diff --git a/xpcom/io/CocoaFileUtils.mm b/xpcom/io/CocoaFileUtils.mm
new file mode 100644
index 000000000..a02b82ac1
--- /dev/null
+++ b/xpcom/io/CocoaFileUtils.mm
@@ -0,0 +1,267 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+// vim:set ts=2 sts=2 sw=2 et cin:
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "CocoaFileUtils.h"
+#include "nsCocoaFeatures.h"
+#include "nsCocoaUtils.h"
+#include <Cocoa/Cocoa.h>
+#include "nsObjCExceptions.h"
+#include "nsDebug.h"
+
+// Need to cope with us using old versions of the SDK and needing this on 10.10+
+#if !defined(MAC_OS_X_VERSION_10_10) || (MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_10)
+const CFStringRef kCFURLQuarantinePropertiesKey = CFSTR("NSURLQuarantinePropertiesKey");
+#endif
+
+namespace CocoaFileUtils {
+
+nsresult RevealFileInFinder(CFURLRef url)
+{
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
+
+  if (NS_WARN_IF(!url))
+    return NS_ERROR_INVALID_ARG;
+
+  NSAutoreleasePool* ap = [[NSAutoreleasePool alloc] init];
+  BOOL success = [[NSWorkspace sharedWorkspace] selectFile:[(NSURL*)url path] inFileViewerRootedAtPath:@""];
+  [ap release];
+
+  return (success ? NS_OK : NS_ERROR_FAILURE);
+
+  NS_OBJC_END_TRY_ABORT_BLOCK_NSRESULT;
+}
+
+nsresult OpenURL(CFURLRef url)
+{
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
+
+  if (NS_WARN_IF(!url))
+    return NS_ERROR_INVALID_ARG;
+
+  NSAutoreleasePool* ap = [[NSAutoreleasePool alloc] init];
+  BOOL success = [[NSWorkspace sharedWorkspace] openURL:(NSURL*)url];
+  [ap release];
+
+  return (success ? NS_OK : NS_ERROR_FAILURE);
+
+  NS_OBJC_END_TRY_ABORT_BLOCK_NSRESULT;
+}
+
+nsresult GetFileCreatorCode(CFURLRef url, OSType *creatorCode)
+{
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
+
+  if (NS_WARN_IF(!url) || NS_WARN_IF(!creatorCode))
+    return NS_ERROR_INVALID_ARG;
+
+  nsAutoreleasePool localPool;
+
+  NSString *resolvedPath = [[(NSURL*)url path] stringByResolvingSymlinksInPath];
+  if (!resolvedPath) {
+    return NS_ERROR_FAILURE;
+  }
+
+  NSDictionary* dict = [[NSFileManager defaultManager] attributesOfItemAtPath:resolvedPath error:nil];
+  if (!dict) {
+    return NS_ERROR_FAILURE;
+  }
+
+  NSNumber* creatorNum = (NSNumber*)[dict objectForKey:NSFileHFSCreatorCode];
+  if (!creatorNum) {
+    return NS_ERROR_FAILURE;
+  }
+
+  *creatorCode = [creatorNum unsignedLongValue];
+  return NS_OK;
+
+  NS_OBJC_END_TRY_ABORT_BLOCK_NSRESULT;
+}
+
+nsresult SetFileCreatorCode(CFURLRef url, OSType creatorCode)
+{
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
+
+  if (NS_WARN_IF(!url))
+    return NS_ERROR_INVALID_ARG;
+
+  NSAutoreleasePool* ap = [[NSAutoreleasePool alloc] init];
+  NSDictionary* dict = [NSDictionary dictionaryWithObject:[NSNumber numberWithUnsignedLong:creatorCode] forKey:NSFileHFSCreatorCode];
+  BOOL success = [[NSFileManager defaultManager] setAttributes:dict ofItemAtPath:[(NSURL*)url path] error:nil];
+  [ap release];
+  return (success ? NS_OK : NS_ERROR_FAILURE);
+
+  NS_OBJC_END_TRY_ABORT_BLOCK_NSRESULT;
+}
+
+nsresult GetFileTypeCode(CFURLRef url, OSType *typeCode)
+{
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
+
+  if (NS_WARN_IF(!url) || NS_WARN_IF(!typeCode))
+    return NS_ERROR_INVALID_ARG;
+
+  nsAutoreleasePool localPool;
+
+  NSString *resolvedPath = [[(NSURL*)url path] stringByResolvingSymlinksInPath];
+  if (!resolvedPath) {
+    return NS_ERROR_FAILURE;
+  }
+
+  NSDictionary* dict = [[NSFileManager defaultManager] attributesOfItemAtPath:resolvedPath error:nil];
+  if (!dict) {
+    return NS_ERROR_FAILURE;
+  }
+
+  NSNumber* typeNum = (NSNumber*)[dict objectForKey:NSFileHFSTypeCode];
+  if (!typeNum) {
+    return NS_ERROR_FAILURE;
+  }
+
+  *typeCode = [typeNum unsignedLongValue];
+  return NS_OK;
+
+  NS_OBJC_END_TRY_ABORT_BLOCK_NSRESULT;
+}
+
+nsresult SetFileTypeCode(CFURLRef url, OSType typeCode)
+{
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
+
+  if (NS_WARN_IF(!url))
+    return NS_ERROR_INVALID_ARG;
+
+  NSAutoreleasePool* ap = [[NSAutoreleasePool alloc] init];
+  NSDictionary* dict = [NSDictionary dictionaryWithObject:[NSNumber numberWithUnsignedLong:typeCode] forKey:NSFileHFSTypeCode];
+  BOOL success = [[NSFileManager defaultManager] setAttributes:dict ofItemAtPath:[(NSURL*)url path] error:nil];
+  [ap release];
+  return (success ? NS_OK : NS_ERROR_FAILURE);
+
+  NS_OBJC_END_TRY_ABORT_BLOCK_NSRESULT;
+}
+
+void AddOriginMetadataToFile(const CFStringRef filePath,
+                             const CFURLRef sourceURL,
+                             const CFURLRef referrerURL) {
+  typedef OSStatus (*MDItemSetAttribute_type)(MDItemRef, CFStringRef, CFTypeRef);
+  static MDItemSetAttribute_type mdItemSetAttributeFunc = NULL;
+
+  static bool did_symbol_lookup = false;
+  if (!did_symbol_lookup) {
+    did_symbol_lookup = true;
+
+    CFBundleRef metadata_bundle = ::CFBundleGetBundleWithIdentifier(CFSTR("com.apple.Metadata"));
+    if (!metadata_bundle) {
+      return;
+    }
+
+    mdItemSetAttributeFunc = (MDItemSetAttribute_type)
+        ::CFBundleGetFunctionPointerForName(metadata_bundle, CFSTR("MDItemSetAttribute"));
+  }
+  if (!mdItemSetAttributeFunc) {
+    return;
+  }
+
+  MDItemRef mdItem = ::MDItemCreate(NULL, filePath);
+  if (!mdItem) {
+    return;
+  }
+
+  CFMutableArrayRef list = ::CFArrayCreateMutable(kCFAllocatorDefault, 2, NULL);
+  if (!list) {
+    ::CFRelease(mdItem);
+    return;
+  }
+
+  // The first item in the list is the source URL of the downloaded file.
+  if (sourceURL) {
+    ::CFArrayAppendValue(list, ::CFURLGetString(sourceURL));
+  }
+
+  // If the referrer is known, store that in the second position.
+  if (referrerURL) {
+    ::CFArrayAppendValue(list, ::CFURLGetString(referrerURL));
+  }
+
+  mdItemSetAttributeFunc(mdItem, kMDItemWhereFroms, list);
+
+  ::CFRelease(list);
+  ::CFRelease(mdItem);
+}
+
+void AddQuarantineMetadataToFile(const CFStringRef filePath,
+                                 const CFURLRef sourceURL,
+                                 const CFURLRef referrerURL,
+                                 const bool isFromWeb) {
+  CFURLRef fileURL = ::CFURLCreateWithFileSystemPath(kCFAllocatorDefault,
+                                                     filePath,
+                                                     kCFURLPOSIXPathStyle,
+                                                     false);
+
+  // The properties key changed in 10.10:
+  CFStringRef quarantinePropKey;
+  if (nsCocoaFeatures::OnYosemiteOrLater()) {
+    quarantinePropKey = kCFURLQuarantinePropertiesKey;
+  } else {
+    quarantinePropKey = kLSItemQuarantineProperties;
+  }
+  CFDictionaryRef quarantineProps = NULL;
+  Boolean success = ::CFURLCopyResourcePropertyForKey(fileURL,
+                                                      quarantinePropKey,
+                                                      &quarantineProps,
+                                                      NULL);
+
+  // If there aren't any quarantine properties then the user probably
+  // set up an exclusion and we don't need to add metadata.
+  if (!success || !quarantineProps) {
+    ::CFRelease(fileURL);
+    return;
+  }
+
+  // We don't know what to do if the props aren't a dictionary.
+  if (::CFGetTypeID(quarantineProps) != ::CFDictionaryGetTypeID()) {
+    ::CFRelease(fileURL);
+    ::CFRelease(quarantineProps);
+    return;
+  }
+
+  // Make a mutable copy of the properties.
+  CFMutableDictionaryRef mutQuarantineProps =
+    ::CFDictionaryCreateMutableCopy(kCFAllocatorDefault, 0, (CFDictionaryRef)quarantineProps);
+  ::CFRelease(quarantineProps);
+
+  // Add metadata that the OS couldn't infer.
+
+  if (!::CFDictionaryGetValue(mutQuarantineProps, kLSQuarantineTypeKey)) {
+    CFStringRef type = isFromWeb ? kLSQuarantineTypeWebDownload : kLSQuarantineTypeOtherDownload;
+    ::CFDictionarySetValue(mutQuarantineProps, kLSQuarantineTypeKey, type);
+  }
+
+  if (!::CFDictionaryGetValue(mutQuarantineProps, kLSQuarantineOriginURLKey) && referrerURL) {
+    ::CFDictionarySetValue(mutQuarantineProps, kLSQuarantineOriginURLKey, referrerURL);
+  }
+
+  if (!::CFDictionaryGetValue(mutQuarantineProps, kLSQuarantineDataURLKey) && sourceURL) {
+    ::CFDictionarySetValue(mutQuarantineProps, kLSQuarantineDataURLKey, sourceURL);
+  }
+
+  // Set quarantine properties on file.
+  ::CFURLSetResourcePropertyForKey(fileURL,
+                                   quarantinePropKey,
+                                   mutQuarantineProps,
+                                   NULL);
+
+  ::CFRelease(fileURL);
+  ::CFRelease(mutQuarantineProps);
+}
+
+CFURLRef GetTemporaryFolderCFURLRef()
+{
+  NSString* tempDir = ::NSTemporaryDirectory();
+  return tempDir == nil ? NULL : (CFURLRef)[NSURL fileURLWithPath:tempDir
+                                                      isDirectory:YES];
+}
+
+} // namespace CocoaFileUtils
diff --git a/xpcom/io/FileUtilsWin.cpp b/xpcom/io/FileUtilsWin.cpp
new file mode 100644
index 000000000..732c074f7
--- /dev/null
+++ b/xpcom/io/FileUtilsWin.cpp
@@ -0,0 +1,75 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "FileUtilsWin.h"
+
+#include <windows.h>
+#include <psapi.h>
+
+#include "mozilla/Unused.h"
+#include "nsWindowsHelpers.h"
+#include "GeckoProfiler.h"
+
+namespace {
+
+// Scoped type used by HandleToFilename
+struct ScopedMappedViewTraits
+{
+  typedef void* type;
+  static void* empty()
+  {
+    return nullptr;
+  }
+  static void release(void* aPtr)
+  {
+    if (aPtr) {
+      mozilla::Unused << UnmapViewOfFile(aPtr);
+    }
+  }
+};
+typedef mozilla::Scoped<ScopedMappedViewTraits> ScopedMappedView;
+
+} // namespace
+
+namespace mozilla {
+
+bool
+HandleToFilename(HANDLE aHandle, const LARGE_INTEGER& aOffset,
+                 nsAString& aFilename)
+{
+  PROFILER_LABEL_FUNC(js::ProfileEntry::Category::NETWORK);
+
+  aFilename.Truncate();
+  // This implementation is nice because it uses fully documented APIs that
+  // are available on all Windows versions that we support.
+  nsAutoHandle fileMapping(CreateFileMapping(aHandle, nullptr, PAGE_READONLY,
+                                             0, 1, nullptr));
+  if (!fileMapping) {
+    return false;
+  }
+  ScopedMappedView view(MapViewOfFile(fileMapping, FILE_MAP_READ,
+                                      aOffset.HighPart, aOffset.LowPart, 1));
+  if (!view) {
+    return false;
+  }
+  nsAutoString mappedFilename;
+  DWORD len = 0;
+  SetLastError(ERROR_SUCCESS);
+  do {
+    mappedFilename.SetLength(mappedFilename.Length() + MAX_PATH);
+    len = GetMappedFileNameW(GetCurrentProcess(), view,
+                             wwc(mappedFilename.BeginWriting()),
+                             mappedFilename.Length());
+  } while (!len && GetLastError() == ERROR_INSUFFICIENT_BUFFER);
+  if (!len) {
+    return false;
+  }
+  mappedFilename.Truncate(len);
+  return NtPathToDosPath(mappedFilename, aFilename);
+}
+
+} // namespace mozilla
+
diff --git a/xpcom/io/FileUtilsWin.h b/xpcom/io/FileUtilsWin.h
new file mode 100644
index 000000000..e32e9fd6e
--- /dev/null
+++ b/xpcom/io/FileUtilsWin.h
@@ -0,0 +1,144 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_FileUtilsWin_h
+#define mozilla_FileUtilsWin_h
+
+#include <windows.h>
+
+#include "mozilla/Scoped.h"
+#include "nsStringGlue.h"
+
+namespace mozilla {
+
+inline bool
+EnsureLongPath(nsAString& aDosPath)
+{
+  uint32_t aDosPathOriginalLen = aDosPath.Length();
+  auto inputPath = PromiseFlatString(aDosPath);
+  // Try to get the long path, or else get the required length of the long path
+  DWORD longPathLen = GetLongPathNameW(inputPath.get(),
+                                       reinterpret_cast<wchar_t*>(aDosPath.BeginWriting()),
+                                       aDosPathOriginalLen);
+  if (longPathLen == 0) {
+    return false;
+  }
+  aDosPath.SetLength(longPathLen);
+  if (longPathLen <= aDosPathOriginalLen) {
+    // Our string happened to be long enough for the first call to succeed.
+    return true;
+  }
+  // Now we have a large enough buffer, get the actual string
+  longPathLen = GetLongPathNameW(inputPath.get(),
+                                 reinterpret_cast<wchar_t*>(aDosPath.BeginWriting()), aDosPath.Length());
+  if (longPathLen == 0) {
+    return false;
+  }
+  // This success check should always be less-than because longPathLen excludes
+  // the null terminator on success, but includes it in the first call that
+  // returned the required size.
+  if (longPathLen < aDosPath.Length()) {
+    aDosPath.SetLength(longPathLen);
+    return true;
+  }
+  // We shouldn't reach this, but if we do then it's a failure!
+  return false;
+}
+
+inline bool
+NtPathToDosPath(const nsAString& aNtPath, nsAString& aDosPath)
+{
+  aDosPath.Truncate();
+  if (aNtPath.IsEmpty()) {
+    return true;
+  }
+  NS_NAMED_LITERAL_STRING(symLinkPrefix, "\\??\\");
+  uint32_t ntPathLen = aNtPath.Length();
+  uint32_t symLinkPrefixLen = symLinkPrefix.Length();
+  if (ntPathLen >= 6 && aNtPath.CharAt(5) == L':' &&
+      ntPathLen >= symLinkPrefixLen &&
+      Substring(aNtPath, 0, symLinkPrefixLen).Equals(symLinkPrefix)) {
+    // Symbolic link for DOS device. Just strip off the prefix.
+    aDosPath = aNtPath;
+    aDosPath.Cut(0, 4);
+    return true;
+  }
+  nsAutoString logicalDrives;
+  DWORD len = 0;
+  while (true) {
+    len = GetLogicalDriveStringsW(
+      len, reinterpret_cast<wchar_t*>(logicalDrives.BeginWriting()));
+    if (!len) {
+      return false;
+    } else if (len > logicalDrives.Length()) {
+      logicalDrives.SetLength(len);
+    } else {
+      break;
+    }
+  }
+  const char16_t* cur = logicalDrives.BeginReading();
+  const char16_t* end = logicalDrives.EndReading();
+  nsString targetPath;
+  targetPath.SetLength(MAX_PATH);
+  wchar_t driveTemplate[] = L" :";
+  do {
+    // Unfortunately QueryDosDevice doesn't support the idiom for querying the
+    // output buffer size, so it may require retries.
+    driveTemplate[0] = *cur;
+    DWORD targetPathLen = 0;
+    SetLastError(ERROR_SUCCESS);
+    while (true) {
+      targetPathLen = QueryDosDeviceW(driveTemplate,
+                                      reinterpret_cast<wchar_t*>(targetPath.BeginWriting()),
+                                      targetPath.Length());
+      if (targetPathLen || GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
+        break;
+      }
+      targetPath.SetLength(targetPath.Length() * 2);
+    }
+    if (targetPathLen) {
+      // Need to use wcslen here because targetPath contains embedded NULL chars
+      size_t firstTargetPathLen = wcslen(targetPath.get());
+      const char16_t* pathComponent = aNtPath.BeginReading() +
+                                      firstTargetPathLen;
+      bool found = _wcsnicmp(char16ptr_t(aNtPath.BeginReading()), targetPath.get(),
+                             firstTargetPathLen) == 0 &&
+                   *pathComponent == L'\\';
+      if (found) {
+        aDosPath = driveTemplate;
+        aDosPath += pathComponent;
+        return EnsureLongPath(aDosPath);
+      }
+    }
+    // Advance to the next NUL character in logicalDrives
+    while (*cur++);
+  } while (cur != end);
+  // Try to handle UNC paths. NB: This must happen after we've checked drive
+  // mappings in case a UNC path is mapped to a drive!
+  NS_NAMED_LITERAL_STRING(uncPrefix, "\\\\");
+  NS_NAMED_LITERAL_STRING(deviceMupPrefix, "\\Device\\Mup\\");
+  if (StringBeginsWith(aNtPath, deviceMupPrefix)) {
+    aDosPath = uncPrefix;
+    aDosPath += Substring(aNtPath, deviceMupPrefix.Length());
+    return true;
+  }
+  NS_NAMED_LITERAL_STRING(deviceLanmanRedirectorPrefix,
+                          "\\Device\\LanmanRedirector\\");
+  if (StringBeginsWith(aNtPath, deviceLanmanRedirectorPrefix)) {
+    aDosPath = uncPrefix;
+    aDosPath += Substring(aNtPath, deviceLanmanRedirectorPrefix.Length());
+    return true;
+  }
+  return false;
+}
+
+bool
+HandleToFilename(HANDLE aHandle, const LARGE_INTEGER& aOffset,
+                 nsAString& aFilename);
+
+} // namespace mozilla
+
+#endif // mozilla_FileUtilsWin_h
diff --git a/xpcom/io/SlicedInputStream.cpp b/xpcom/io/SlicedInputStream.cpp
new file mode 100644
index 000000000..7d5fc2b05
--- /dev/null
+++ b/xpcom/io/SlicedInputStream.cpp
@@ -0,0 +1,209 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "SlicedInputStream.h"
+#include "nsISeekableStream.h"
+#include "nsStreamUtils.h"
+
+NS_IMPL_ISUPPORTS(SlicedInputStream, nsIInputStream,
+                  nsICloneableInputStream, nsIAsyncInputStream)
+
+SlicedInputStream::SlicedInputStream(nsIInputStream* aInputStream,
+                                     uint64_t aStart, uint64_t aLength)
+  : mInputStream(aInputStream)
+  , mStart(aStart)
+  , mLength(aLength)
+  , mCurPos(0)
+  , mClosed(false)
+{
+  MOZ_ASSERT(aInputStream);
+}
+
+SlicedInputStream::~SlicedInputStream()
+{}
+
+NS_IMETHODIMP
+SlicedInputStream::Close()
+{
+  mClosed = true;
+  return NS_OK;
+}
+
+// nsIInputStream interface
+
+NS_IMETHODIMP
+SlicedInputStream::Available(uint64_t* aLength)
+{
+  if (mClosed) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  nsresult rv = mInputStream->Available(aLength);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  // Let's remove extra length from the end.
+  if (*aLength + mCurPos > mStart + mLength) {
+    *aLength -= XPCOM_MIN(*aLength, (*aLength + mCurPos) - (mStart + mLength));
+  }
+
+  // Let's remove extra length from the begin.
+  if (mCurPos < mStart) {
+    *aLength -= XPCOM_MIN(*aLength, mStart - mCurPos);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+SlicedInputStream::Read(char* aBuffer, uint32_t aCount, uint32_t* aReadCount)
+{
+  return ReadSegments(NS_CopySegmentToBuffer, aBuffer, aCount, aReadCount);
+}
+
+NS_IMETHODIMP
+SlicedInputStream::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
+                                uint32_t aCount, uint32_t *aResult)
+{
+  uint32_t result;
+
+  if (!aResult) {
+    aResult = &result;
+  }
+
+  *aResult = 0;
+
+  if (mClosed) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  if (mCurPos < mStart) {
+    nsCOMPtr<nsISeekableStream> seekableStream =
+      do_QueryInterface(mInputStream);
+    if (seekableStream) {
+      nsresult rv = seekableStream->Seek(nsISeekableStream::NS_SEEK_SET,
+                                         mStart);
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        return rv;
+      }
+
+      mCurPos = mStart;
+    } else {
+      char buf[4096];
+      while (mCurPos < mStart) {
+	uint32_t bytesRead;
+	uint64_t bufCount = XPCOM_MIN(mStart - mCurPos, (uint64_t)sizeof(buf));
+	nsresult rv = mInputStream->Read(buf, bufCount, &bytesRead);
+	if (NS_WARN_IF(NS_FAILED(rv)) || bytesRead == 0) {
+	  return rv;
+	}
+
+         mCurPos += bytesRead;
+      }
+    }
+  }
+
+  // Let's reduce aCount in case it's too big.
+  if (mCurPos + aCount > mStart + mLength) {
+    aCount = mStart + mLength - mCurPos;
+  }
+
+  char buf[4096];
+  while (mCurPos < mStart + mLength && *aResult < aCount) {
+    uint32_t bytesRead;
+    uint64_t bufCount = XPCOM_MIN(aCount - *aResult, (uint32_t)sizeof(buf));
+    nsresult rv = mInputStream->Read(buf, bufCount, &bytesRead);
+    if (NS_WARN_IF(NS_FAILED(rv)) || bytesRead == 0) {
+      return rv;
+    }
+
+    mCurPos += bytesRead;
+
+    uint32_t bytesWritten = 0;
+    while (bytesWritten < bytesRead) {
+      uint32_t writerCount = 0;
+      rv = aWriter(this, aClosure, buf + bytesWritten, *aResult,
+                   bytesRead - bytesWritten, &writerCount);
+      if (NS_FAILED(rv) || writerCount == 0) {
+	return NS_OK;
+      }
+
+      MOZ_ASSERT(writerCount <= bytesRead - bytesWritten);
+      bytesWritten += writerCount;
+      *aResult += writerCount;
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+SlicedInputStream::IsNonBlocking(bool* aNonBlocking)
+{
+  return mInputStream->IsNonBlocking(aNonBlocking);
+}
+
+// nsICloneableInputStream interface
+
+NS_IMETHODIMP
+SlicedInputStream::GetCloneable(bool* aCloneable)
+{
+  *aCloneable = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+SlicedInputStream::Clone(nsIInputStream** aResult)
+{
+  nsCOMPtr<nsIInputStream> clonedStream;
+  nsCOMPtr<nsIInputStream> replacementStream;
+
+  nsresult rv = NS_CloneInputStream(mInputStream, getter_AddRefs(clonedStream),
+                                    getter_AddRefs(replacementStream));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  if (replacementStream) {
+    mInputStream = replacementStream.forget();
+  }
+
+  nsCOMPtr<nsIInputStream> sis =
+    new SlicedInputStream(clonedStream, mStart, mLength);
+
+  sis.forget(aResult);
+  return NS_OK;
+}
+
+// nsIAsyncInputStream interface
+
+NS_IMETHODIMP
+SlicedInputStream::CloseWithStatus(nsresult aStatus)
+{
+  nsCOMPtr<nsIAsyncInputStream> asyncStream =
+    do_QueryInterface(mInputStream);
+  if (!asyncStream) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return asyncStream->CloseWithStatus(aStatus);
+}
+
+NS_IMETHODIMP
+SlicedInputStream::AsyncWait(nsIInputStreamCallback* aCallback,
+                             uint32_t aFlags,
+                             uint32_t aRequestedCount,
+                             nsIEventTarget* aEventTarget)
+{
+  nsCOMPtr<nsIAsyncInputStream> asyncStream =
+    do_QueryInterface(mInputStream);
+  if (!asyncStream) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return asyncStream->AsyncWait(aCallback, aFlags, aRequestedCount,
+                                aEventTarget);
+}
diff --git a/xpcom/io/SlicedInputStream.h b/xpcom/io/SlicedInputStream.h
new file mode 100644
index 000000000..6c38fc39f
--- /dev/null
+++ b/xpcom/io/SlicedInputStream.h
@@ -0,0 +1,50 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef SlicedInputStream_h
+#define SlicedInputStream_h
+
+#include "mozilla/Attributes.h"
+#include "nsCOMPtr.h"
+#include "nsIAsyncInputStream.h"
+#include "nsICloneableInputStream.h"
+
+// A wrapper for a slice of an underlying input stream.
+
+class SlicedInputStream final : public nsIAsyncInputStream
+                              , public nsICloneableInputStream
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIINPUTSTREAM
+  NS_DECL_NSICLONEABLEINPUTSTREAM
+  NS_DECL_NSIASYNCINPUTSTREAM
+
+  // Create an input stream whose data comes from a slice of aInputStream.  The
+  // slice begins at aStart bytes beyond aInputStream's current position, and
+  // extends for a maximum of aLength bytes.  If aInputStream contains fewer
+  // than aStart bytes, reading from SlicedInputStream returns no data.  If
+  // aInputStream contains more than aStart bytes, but fewer than aStart +
+  // aLength bytes, reading from SlicedInputStream returns as many bytes as can
+  // be consumed from aInputStream after reading aLength bytes.
+  //
+  // aInputStream should not be read from after constructing a
+  // SlicedInputStream wrapper around it.
+
+  SlicedInputStream(nsIInputStream* aInputStream,
+                    uint64_t aStart, uint64_t aLength);
+
+private:
+  ~SlicedInputStream();
+
+  nsCOMPtr<nsIInputStream> mInputStream;
+  uint64_t mStart;
+  uint64_t mLength;
+  uint64_t mCurPos;
+
+  bool mClosed;
+};
+
+#endif // SlicedInputStream_h
diff --git a/xpcom/io/SnappyCompressOutputStream.cpp b/xpcom/io/SnappyCompressOutputStream.cpp
new file mode 100644
index 000000000..89b8a0808
--- /dev/null
+++ b/xpcom/io/SnappyCompressOutputStream.cpp
@@ -0,0 +1,256 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/SnappyCompressOutputStream.h"
+
+#include <algorithm>
+#include "nsStreamUtils.h"
+#include "snappy/snappy.h"
+
+namespace mozilla {
+
+NS_IMPL_ISUPPORTS(SnappyCompressOutputStream, nsIOutputStream);
+
+// static
+const size_t
+SnappyCompressOutputStream::kMaxBlockSize = snappy::kBlockSize;
+
+SnappyCompressOutputStream::SnappyCompressOutputStream(nsIOutputStream* aBaseStream,
+                                                       size_t aBlockSize)
+ : mBaseStream(aBaseStream)
+ , mBlockSize(std::min(aBlockSize, kMaxBlockSize))
+ , mNextByte(0)
+ , mCompressedBufferLength(0)
+ , mStreamIdentifierWritten(false)
+{
+  MOZ_ASSERT(mBlockSize > 0);
+
+  // This implementation only supports sync base streams.  Verify this in debug
+  // builds.  Note, this can be simpler than the check in
+  // SnappyUncompressInputStream because we don't have to deal with the
+  // nsStringInputStream oddness of being non-blocking and sync.
+#ifdef DEBUG
+  bool baseNonBlocking;
+  nsresult rv = mBaseStream->IsNonBlocking(&baseNonBlocking);
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+  MOZ_ASSERT(!baseNonBlocking);
+#endif
+}
+
+size_t
+SnappyCompressOutputStream::BlockSize() const
+{
+  return mBlockSize;
+}
+
+NS_IMETHODIMP
+SnappyCompressOutputStream::Close()
+{
+  if (!mBaseStream) {
+    return NS_OK;
+  }
+
+  nsresult rv = Flush();
+  if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+
+  mBaseStream->Close();
+  mBaseStream = nullptr;
+
+  mBuffer = nullptr;
+  mCompressedBuffer = nullptr;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+SnappyCompressOutputStream::Flush()
+{
+  if (!mBaseStream) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  nsresult rv = FlushToBaseStream();
+  if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+
+  mBaseStream->Flush();
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+SnappyCompressOutputStream::Write(const char* aBuf, uint32_t aCount,
+                                  uint32_t* aResultOut)
+{
+  return WriteSegments(NS_CopySegmentToBuffer, const_cast<char*>(aBuf), aCount,
+                       aResultOut);
+}
+
+NS_IMETHODIMP
+SnappyCompressOutputStream::WriteFrom(nsIInputStream*, uint32_t, uint32_t*)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+SnappyCompressOutputStream::WriteSegments(nsReadSegmentFun aReader,
+                                          void* aClosure,
+                                          uint32_t aCount,
+                                          uint32_t* aBytesWrittenOut)
+{
+  *aBytesWrittenOut = 0;
+
+  if (!mBaseStream) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  if (!mBuffer) {
+    mBuffer.reset(new (fallible) char[mBlockSize]);
+    if (NS_WARN_IF(!mBuffer)) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+  }
+
+  while (aCount > 0) {
+    // Determine how much space is left in our flat, uncompressed buffer.
+    MOZ_ASSERT(mNextByte <= mBlockSize);
+    uint32_t remaining = mBlockSize - mNextByte;
+
+    // If it is full, then compress and flush the data to the base stream.
+    if (remaining == 0) {
+      nsresult rv = FlushToBaseStream();
+      if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+
+      // Now the entire buffer should be available for copying.
+      MOZ_ASSERT(!mNextByte);
+      remaining = mBlockSize;
+    }
+
+    uint32_t numToRead = std::min(remaining, aCount);
+    uint32_t numRead = 0;
+
+    nsresult rv = aReader(this, aClosure, &mBuffer[mNextByte],
+                          *aBytesWrittenOut, numToRead, &numRead);
+
+    // As defined in nsIOutputStream.idl, do not pass reader func errors.
+    if (NS_FAILED(rv)) {
+      return NS_OK;
+    }
+
+    // End-of-file
+    if (numRead == 0) {
+      return NS_OK;
+    }
+
+    mNextByte += numRead;
+    *aBytesWrittenOut += numRead;
+    aCount -= numRead;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+SnappyCompressOutputStream::IsNonBlocking(bool* aNonBlockingOut)
+{
+  *aNonBlockingOut = false;
+  return NS_OK;
+}
+
+SnappyCompressOutputStream::~SnappyCompressOutputStream()
+{
+  Close();
+}
+
+nsresult
+SnappyCompressOutputStream::FlushToBaseStream()
+{
+  MOZ_ASSERT(mBaseStream);
+
+  // Lazily create the compressed buffer on our first flush.  This
+  // allows us to report OOM during stream operation.  This buffer
+  // will then get re-used until the stream is closed.
+  if (!mCompressedBuffer) {
+    mCompressedBufferLength = MaxCompressedBufferLength(mBlockSize);
+    mCompressedBuffer.reset(new (fallible) char[mCompressedBufferLength]);
+    if (NS_WARN_IF(!mCompressedBuffer)) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+  }
+
+  // The first chunk must be a StreamIdentifier chunk.  Write it out
+  // if we have not done so already.
+  nsresult rv = MaybeFlushStreamIdentifier();
+  if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+
+  // Compress the data to our internal compressed buffer.
+  size_t compressedLength;
+  rv = WriteCompressedData(mCompressedBuffer.get(), mCompressedBufferLength,
+                           mBuffer.get(), mNextByte, &compressedLength);
+  if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+  MOZ_ASSERT(compressedLength > 0);
+
+  mNextByte = 0;
+
+  // Write the compressed buffer out to the base stream.
+  uint32_t numWritten = 0;
+  rv = WriteAll(mCompressedBuffer.get(), compressedLength, &numWritten);
+  if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+  MOZ_ASSERT(compressedLength == numWritten);
+
+  return NS_OK;
+}
+
+nsresult
+SnappyCompressOutputStream::MaybeFlushStreamIdentifier()
+{
+  MOZ_ASSERT(mCompressedBuffer);
+
+  if (mStreamIdentifierWritten) {
+    return NS_OK;
+  }
+
+  // Build the StreamIdentifier in our compressed buffer.
+  size_t compressedLength;
+  nsresult rv = WriteStreamIdentifier(mCompressedBuffer.get(),
+                                      mCompressedBufferLength,
+                                      &compressedLength);
+  if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+
+  // Write the compressed buffer out to the base stream.
+  uint32_t numWritten = 0;
+  rv = WriteAll(mCompressedBuffer.get(), compressedLength, &numWritten);
+  if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+  MOZ_ASSERT(compressedLength == numWritten);
+
+  mStreamIdentifierWritten = true;
+
+  return NS_OK;
+}
+
+nsresult
+SnappyCompressOutputStream::WriteAll(const char* aBuf, uint32_t aCount,
+                                     uint32_t* aBytesWrittenOut)
+{
+  *aBytesWrittenOut = 0;
+
+  if (!mBaseStream) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  uint32_t offset = 0;
+  while (aCount > 0) {
+    uint32_t numWritten = 0;
+    nsresult rv = mBaseStream->Write(aBuf + offset, aCount, &numWritten);
+    if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+    offset += numWritten;
+    aCount -= numWritten;
+    *aBytesWrittenOut += numWritten;
+  }
+
+  return NS_OK;
+}
+
+} // namespace mozilla
diff --git a/xpcom/io/SnappyCompressOutputStream.h b/xpcom/io/SnappyCompressOutputStream.h
new file mode 100644
index 000000000..36c47e66e
--- /dev/null
+++ b/xpcom/io/SnappyCompressOutputStream.h
@@ -0,0 +1,69 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_SnappyCompressOutputStream_h__
+#define mozilla_SnappyCompressOutputStream_h__
+
+#include "mozilla/Attributes.h"
+#include "mozilla/UniquePtr.h"
+#include "nsCOMPtr.h"
+#include "nsIOutputStream.h"
+#include "nsISupportsImpl.h"
+#include "SnappyFrameUtils.h"
+
+namespace mozilla {
+
+class SnappyCompressOutputStream final : public nsIOutputStream
+                                       , protected detail::SnappyFrameUtils
+{
+public:
+  // Maximum compression block size.
+  static const size_t kMaxBlockSize;
+
+  // Construct a new blocking output stream to compress data to
+  // the given base stream.  The base stream must also be blocking.
+  // The compression block size may optionally be set to a value
+  // up to kMaxBlockSize.
+  explicit SnappyCompressOutputStream(nsIOutputStream* aBaseStream,
+                                      size_t aBlockSize = kMaxBlockSize);
+
+  // The compression block size.  To optimize stream performance
+  // try to write to the stream in segments at least this size.
+  size_t BlockSize() const;
+
+private:
+  virtual ~SnappyCompressOutputStream();
+
+  nsresult FlushToBaseStream();
+  nsresult MaybeFlushStreamIdentifier();
+  nsresult WriteAll(const char* aBuf, uint32_t aCount,
+                    uint32_t* aBytesWrittenOut);
+
+  nsCOMPtr<nsIOutputStream> mBaseStream;
+  const size_t mBlockSize;
+
+  // Buffer holding copied uncompressed data.  This must be copied here
+  // so that the compression can be performed on a single flat buffer.
+  mozilla::UniquePtr<char[]> mBuffer;
+
+  // The next byte in the uncompressed data to copy incoming data to.
+  size_t mNextByte;
+
+  // Buffer holding the resulting compressed data.
+  mozilla::UniquePtr<char[]> mCompressedBuffer;
+  size_t mCompressedBufferLength;
+
+  // The first thing written to the stream must be a stream identifier.
+  bool mStreamIdentifierWritten;
+
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIOUTPUTSTREAM
+};
+
+} // namespace mozilla
+
+#endif // mozilla_SnappyCompressOutputStream_h__
diff --git a/xpcom/io/SnappyFrameUtils.cpp b/xpcom/io/SnappyFrameUtils.cpp
new file mode 100644
index 000000000..97883a362
--- /dev/null
+++ b/xpcom/io/SnappyFrameUtils.cpp
@@ -0,0 +1,258 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/SnappyFrameUtils.h"
+
+#include "crc32c.h"
+#include "mozilla/EndianUtils.h"
+#include "nsDebug.h"
+#include "snappy/snappy.h"
+
+namespace {
+
+using mozilla::detail::SnappyFrameUtils;
+using mozilla::NativeEndian;
+
+SnappyFrameUtils::ChunkType ReadChunkType(uint8_t aByte)
+{
+  if (aByte == 0xff)  {
+    return SnappyFrameUtils::StreamIdentifier;
+  } else if (aByte == 0x00) {
+    return SnappyFrameUtils::CompressedData;
+  } else if (aByte == 0x01) {
+    return SnappyFrameUtils::UncompressedData;
+  } else if (aByte == 0xfe) {
+    return SnappyFrameUtils::Padding;
+  }
+
+  return SnappyFrameUtils::Reserved;
+}
+
+void WriteChunkType(char* aDest, SnappyFrameUtils::ChunkType aType)
+{
+  unsigned char* dest = reinterpret_cast<unsigned char*>(aDest);
+  if (aType == SnappyFrameUtils::StreamIdentifier) {
+    *dest = 0xff;
+  } else if (aType == SnappyFrameUtils::CompressedData) {
+    *dest = 0x00;
+  } else if (aType == SnappyFrameUtils::UncompressedData) {
+    *dest = 0x01;
+  } else if (aType == SnappyFrameUtils::Padding) {
+    *dest = 0xfe;
+  } else {
+    *dest = 0x02;
+  }
+}
+
+void WriteUInt24(char* aBuf, uint32_t aVal)
+{
+  MOZ_ASSERT(!(aVal & 0xff000000));
+  uint32_t tmp = NativeEndian::swapToLittleEndian(aVal);
+  memcpy(aBuf, &tmp, 3);
+}
+
+uint32_t ReadUInt24(const char* aBuf)
+{
+  uint32_t val = 0;
+  memcpy(&val, aBuf, 3);
+  return NativeEndian::swapFromLittleEndian(val);
+}
+
+// This mask is explicitly defined in the snappy framing_format.txt file.
+uint32_t MaskChecksum(uint32_t aValue)
+{
+  return ((aValue >> 15) | (aValue << 17)) + 0xa282ead8;
+}
+
+} // namespace
+
+namespace mozilla {
+namespace detail {
+
+using mozilla::LittleEndian;
+
+// static
+nsresult
+SnappyFrameUtils::WriteStreamIdentifier(char* aDest, size_t aDestLength,
+                                        size_t* aBytesWrittenOut)
+{
+  if (NS_WARN_IF(aDestLength < (kHeaderLength + kStreamIdentifierDataLength))) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  WriteChunkType(aDest, StreamIdentifier);
+  aDest[1] = 0x06;  // Data length
+  aDest[2] = 0x00;
+  aDest[3] = 0x00;
+  aDest[4] = 0x73;  // "sNaPpY"
+  aDest[5] = 0x4e;
+  aDest[6] = 0x61;
+  aDest[7] = 0x50;
+  aDest[8] = 0x70;
+  aDest[9] = 0x59;
+
+  static_assert(kHeaderLength + kStreamIdentifierDataLength == 10,
+                "StreamIdentifier chunk should be exactly 10 bytes long");
+  *aBytesWrittenOut = kHeaderLength + kStreamIdentifierDataLength;
+
+  return NS_OK;
+}
+
+// static
+nsresult
+SnappyFrameUtils::WriteCompressedData(char* aDest, size_t aDestLength,
+                                      const char* aData, size_t aDataLength,
+                                      size_t* aBytesWrittenOut)
+{
+  *aBytesWrittenOut = 0;
+
+  size_t neededLength = MaxCompressedBufferLength(aDataLength);
+  if (NS_WARN_IF(aDestLength < neededLength)) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  size_t offset = 0;
+
+  WriteChunkType(aDest, CompressedData);
+  offset += kChunkTypeLength;
+
+  // Skip length for now and write it out after we know the compressed length.
+  size_t lengthOffset = offset;
+  offset += kChunkLengthLength;
+
+  uint32_t crc = ComputeCrc32c(~0, reinterpret_cast<const unsigned char*>(aData),
+                               aDataLength);
+  uint32_t maskedCrc = MaskChecksum(crc);
+  LittleEndian::writeUint32(aDest + offset, maskedCrc);
+  offset += kCRCLength;
+
+  size_t compressedLength;
+  snappy::RawCompress(aData, aDataLength, aDest + offset, &compressedLength);
+
+  // Go back and write the data length.
+  size_t dataLength = compressedLength + kCRCLength;
+  WriteUInt24(aDest + lengthOffset, dataLength);
+
+  *aBytesWrittenOut = kHeaderLength + dataLength;
+
+  return NS_OK;
+}
+
+// static
+nsresult
+SnappyFrameUtils::ParseHeader(const char* aSource, size_t aSourceLength,
+                              ChunkType* aTypeOut, size_t* aDataLengthOut)
+{
+  if (NS_WARN_IF(aSourceLength < kHeaderLength)) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  *aTypeOut = ReadChunkType(aSource[0]);
+  *aDataLengthOut = ReadUInt24(aSource + kChunkTypeLength);
+
+  return NS_OK;
+}
+
+// static
+nsresult
+SnappyFrameUtils::ParseData(char* aDest, size_t aDestLength,
+                            ChunkType aType, const char* aData,
+                            size_t aDataLength,
+                            size_t* aBytesWrittenOut, size_t* aBytesReadOut)
+{
+  switch(aType) {
+    case StreamIdentifier:
+      return ParseStreamIdentifier(aDest, aDestLength, aData, aDataLength,
+                                   aBytesWrittenOut, aBytesReadOut);
+
+    case CompressedData:
+      return ParseCompressedData(aDest, aDestLength, aData, aDataLength,
+                                 aBytesWrittenOut, aBytesReadOut);
+
+    // TODO: support other snappy chunk types
+    default:
+      MOZ_ASSERT_UNREACHABLE("Unsupported snappy framing chunk type.");
+      return NS_ERROR_NOT_IMPLEMENTED;
+  }
+}
+
+// static
+nsresult
+SnappyFrameUtils::ParseStreamIdentifier(char*, size_t,
+                                        const char* aData, size_t aDataLength,
+                                        size_t* aBytesWrittenOut,
+                                        size_t* aBytesReadOut)
+{
+  *aBytesWrittenOut = 0;
+  *aBytesReadOut = 0;
+  if (NS_WARN_IF(aDataLength != kStreamIdentifierDataLength ||
+                 aData[0] != 0x73 ||
+                 aData[1] != 0x4e ||
+                 aData[2] != 0x61 ||
+                 aData[3] != 0x50 ||
+                 aData[4] != 0x70 ||
+                 aData[5] != 0x59)) {
+    return NS_ERROR_CORRUPTED_CONTENT;
+  }
+  *aBytesReadOut = aDataLength;
+  return NS_OK;
+}
+
+// static
+nsresult
+SnappyFrameUtils::ParseCompressedData(char* aDest, size_t aDestLength,
+                                      const char* aData, size_t aDataLength,
+                                      size_t* aBytesWrittenOut,
+                                      size_t* aBytesReadOut)
+{
+  *aBytesWrittenOut = 0;
+  *aBytesReadOut = 0;
+  size_t offset = 0;
+
+  uint32_t readCrc = LittleEndian::readUint32(aData + offset);
+  offset += kCRCLength;
+
+  size_t uncompressedLength;
+  if (NS_WARN_IF(!snappy::GetUncompressedLength(aData + offset,
+                                                aDataLength - offset,
+                                                &uncompressedLength))) {
+    return NS_ERROR_CORRUPTED_CONTENT;
+  }
+
+  if (NS_WARN_IF(aDestLength < uncompressedLength)) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  if (NS_WARN_IF(!snappy::RawUncompress(aData + offset, aDataLength - offset,
+                                        aDest))) {
+    return NS_ERROR_CORRUPTED_CONTENT;
+  }
+
+  uint32_t crc = ComputeCrc32c(~0, reinterpret_cast<const unsigned char*>(aDest),
+                               uncompressedLength);
+  uint32_t maskedCrc = MaskChecksum(crc);
+  if (NS_WARN_IF(readCrc != maskedCrc)) {
+    return NS_ERROR_CORRUPTED_CONTENT;
+  }
+
+  *aBytesWrittenOut = uncompressedLength;
+  *aBytesReadOut = aDataLength;
+
+  return NS_OK;
+}
+
+// static
+size_t
+SnappyFrameUtils::MaxCompressedBufferLength(size_t aSourceLength)
+{
+  size_t neededLength = kHeaderLength;
+  neededLength += kCRCLength;
+  neededLength += snappy::MaxCompressedLength(aSourceLength);
+  return neededLength;
+}
+
+} // namespace detail
+} // namespace mozilla
diff --git a/xpcom/io/SnappyFrameUtils.h b/xpcom/io/SnappyFrameUtils.h
new file mode 100644
index 000000000..41479b14d
--- /dev/null
+++ b/xpcom/io/SnappyFrameUtils.h
@@ -0,0 +1,85 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_SnappyFrameUtils_h__
+#define mozilla_SnappyFrameUtils_h__
+
+#include "mozilla/Attributes.h"
+#include "nsError.h"
+
+namespace mozilla {
+namespace detail {
+
+//
+// Utility class providing primitives necessary to build streams based
+// on the snappy compressor.  This essentially abstracts the framing format
+// defined in:
+//
+//  other-licences/snappy/src/framing_format.txt
+//
+// NOTE: Currently only the StreamIdentifier and CompressedData chunks are
+//       supported.
+//
+class SnappyFrameUtils
+{
+public:
+  enum ChunkType
+  {
+    Unknown,
+    StreamIdentifier,
+    CompressedData,
+    UncompressedData,
+    Padding,
+    Reserved,
+    ChunkTypeCount
+  };
+
+  static const size_t kChunkTypeLength = 1;
+  static const size_t kChunkLengthLength = 3;
+  static const size_t kHeaderLength = kChunkTypeLength + kChunkLengthLength;
+  static const size_t kStreamIdentifierDataLength = 6;
+  static const size_t kCRCLength = 4;
+
+  static nsresult
+  WriteStreamIdentifier(char* aDest, size_t aDestLength,
+                        size_t* aBytesWrittenOut);
+
+  static nsresult
+  WriteCompressedData(char* aDest, size_t aDestLength,
+                      const char* aData, size_t aDataLength,
+                      size_t* aBytesWrittenOut);
+
+  static nsresult
+  ParseHeader(const char* aSource, size_t aSourceLength, ChunkType* aTypeOut,
+              size_t* aDataLengthOut);
+
+  static nsresult
+  ParseData(char* aDest, size_t aDestLength,
+            ChunkType aType, const char* aData, size_t aDataLength,
+            size_t* aBytesWrittenOut, size_t* aBytesReadOut);
+
+  static nsresult
+  ParseStreamIdentifier(char* aDest, size_t aDestLength,
+                        const char* aData, size_t aDataLength,
+                        size_t* aBytesWrittenOut, size_t* aBytesReadOut);
+
+  static nsresult
+  ParseCompressedData(char* aDest, size_t aDestLength,
+                      const char* aData, size_t aDataLength,
+                      size_t* aBytesWrittenOut, size_t* aBytesReadOut);
+
+  static size_t
+  MaxCompressedBufferLength(size_t aSourceLength);
+
+protected:
+  SnappyFrameUtils() { }
+  virtual ~SnappyFrameUtils() { }
+};
+
+} // namespace detail
+} // namespace mozilla
+
+#endif // mozilla_SnappyFrameUtils_h__
diff --git a/xpcom/io/SnappyUncompressInputStream.cpp b/xpcom/io/SnappyUncompressInputStream.cpp
new file mode 100644
index 000000000..e0a1b6f4c
--- /dev/null
+++ b/xpcom/io/SnappyUncompressInputStream.cpp
@@ -0,0 +1,362 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/SnappyUncompressInputStream.h"
+
+#include <algorithm>
+#include "nsIAsyncInputStream.h"
+#include "nsStreamUtils.h"
+#include "snappy/snappy.h"
+
+namespace mozilla {
+
+NS_IMPL_ISUPPORTS(SnappyUncompressInputStream,
+                  nsIInputStream);
+
+// Putting kCompressedBufferLength inside a function avoids a static
+// constructor.
+static size_t CompressedBufferLength()
+{
+  static size_t kCompressedBufferLength =
+      detail::SnappyFrameUtils::MaxCompressedBufferLength(snappy::kBlockSize);
+
+  MOZ_ASSERT(kCompressedBufferLength > 0);
+  return kCompressedBufferLength;
+}
+
+SnappyUncompressInputStream::SnappyUncompressInputStream(nsIInputStream* aBaseStream)
+  : mBaseStream(aBaseStream)
+  , mUncompressedBytes(0)
+  , mNextByte(0)
+  , mNextChunkType(Unknown)
+  , mNextChunkDataLength(0)
+  , mNeedFirstStreamIdentifier(true)
+{
+  // This implementation only supports sync base streams.  Verify this in debug
+  // builds.  Note, this is a bit complicated because the streams we support
+  // advertise different capabilities:
+  //  - nsFileInputStream - blocking and sync
+  //  - nsStringInputStream - non-blocking and sync
+  //  - nsPipeInputStream - can be blocking, but provides async interface
+#ifdef DEBUG
+  bool baseNonBlocking;
+  nsresult rv = mBaseStream->IsNonBlocking(&baseNonBlocking);
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+  if (baseNonBlocking) {
+    nsCOMPtr<nsIAsyncInputStream> async = do_QueryInterface(mBaseStream);
+    MOZ_ASSERT(!async);
+  }
+#endif
+}
+
+NS_IMETHODIMP
+SnappyUncompressInputStream::Close()
+{
+  if (!mBaseStream) {
+    return NS_OK;
+  }
+
+  mBaseStream->Close();
+  mBaseStream = nullptr;
+
+  mUncompressedBuffer = nullptr;
+  mCompressedBuffer = nullptr;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+SnappyUncompressInputStream::Available(uint64_t* aLengthOut)
+{
+  if (!mBaseStream) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  // If we have uncompressed bytes, then we are done.
+  *aLengthOut = UncompressedLength();
+  if (*aLengthOut > 0) {
+    return NS_OK;
+  }
+
+  // Otherwise, attempt to uncompress bytes until we get something or the
+  // underlying stream is drained.  We loop here because some chunks can
+  // be StreamIdentifiers, padding, etc with no data.
+  uint32_t bytesRead;
+  do {
+    nsresult rv = ParseNextChunk(&bytesRead);
+    if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+    *aLengthOut = UncompressedLength();
+  } while(*aLengthOut == 0 && bytesRead);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+SnappyUncompressInputStream::Read(char* aBuf, uint32_t aCount,
+                                  uint32_t* aBytesReadOut)
+{
+  return ReadSegments(NS_CopySegmentToBuffer, aBuf, aCount, aBytesReadOut);
+}
+
+NS_IMETHODIMP
+SnappyUncompressInputStream::ReadSegments(nsWriteSegmentFun aWriter,
+                                          void* aClosure, uint32_t aCount,
+                                          uint32_t* aBytesReadOut)
+{
+  *aBytesReadOut = 0;
+
+  if (!mBaseStream) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  nsresult rv;
+
+  // Do not try to use the base stream's ReadSegements here.  Its very
+  // unlikely we will get a single buffer that contains all of the compressed
+  // data and therefore would have to copy into our own buffer anyways.
+  // Instead, focus on making efficient use of the Read() interface.
+
+  while (aCount > 0) {
+    // We have some decompressed data in our buffer.  Provide it to the
+    // callers writer function.
+    if (mUncompressedBytes > 0) {
+      MOZ_ASSERT(mUncompressedBuffer);
+      uint32_t remaining = UncompressedLength();
+      uint32_t numToWrite = std::min(aCount, remaining);
+      uint32_t numWritten;
+      rv = aWriter(this, aClosure, &mUncompressedBuffer[mNextByte], *aBytesReadOut,
+                   numToWrite, &numWritten);
+
+      // As defined in nsIInputputStream.idl, do not pass writer func errors.
+      if (NS_FAILED(rv)) {
+        return NS_OK;
+      }
+
+      // End-of-file
+      if (numWritten == 0) {
+        return NS_OK;
+      }
+
+      *aBytesReadOut += numWritten;
+      mNextByte += numWritten;
+      MOZ_ASSERT(mNextByte <= mUncompressedBytes);
+
+      if (mNextByte == mUncompressedBytes) {
+        mNextByte = 0;
+        mUncompressedBytes = 0;
+      }
+
+      aCount -= numWritten;
+
+      continue;
+    }
+
+    // Otherwise uncompress the next chunk and loop.  Any resulting data
+    // will set mUncompressedBytes which we check at the top of the loop.
+    uint32_t bytesRead;
+    rv = ParseNextChunk(&bytesRead);
+    if (NS_FAILED(rv)) { return rv; }
+
+    // If we couldn't read anything and there is no more data to provide
+    // to the caller, then this is eof.
+    if (bytesRead == 0 && mUncompressedBytes == 0) {
+      return NS_OK;
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+SnappyUncompressInputStream::IsNonBlocking(bool* aNonBlockingOut)
+{
+  *aNonBlockingOut = false;
+  return NS_OK;
+}
+
+SnappyUncompressInputStream::~SnappyUncompressInputStream()
+{
+  Close();
+}
+
+nsresult
+SnappyUncompressInputStream::ParseNextChunk(uint32_t* aBytesReadOut)
+{
+  // There must not be any uncompressed data already in mUncompressedBuffer.
+  MOZ_ASSERT(mUncompressedBytes == 0);
+  MOZ_ASSERT(mNextByte == 0);
+
+  nsresult rv;
+  *aBytesReadOut = 0;
+
+  // Lazily create our two buffers so we can report OOM during stream
+  // operation.  These allocations only happens once.  The buffers are reused
+  // until the stream is closed.
+  if (!mUncompressedBuffer) {
+    mUncompressedBuffer.reset(new (fallible) char[snappy::kBlockSize]);
+    if (NS_WARN_IF(!mUncompressedBuffer)) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+  }
+
+  if (!mCompressedBuffer) {
+    mCompressedBuffer.reset(new (fallible) char[CompressedBufferLength()]);
+    if (NS_WARN_IF(!mCompressedBuffer)) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+  }
+
+  // We have no decompressed data and we also have not seen the start of stream
+  // yet. Read and validate the StreamIdentifier chunk.  Also read the next
+  // header to determine the size of the first real data chunk.
+  if (mNeedFirstStreamIdentifier) {
+    const uint32_t firstReadLength = kHeaderLength +
+                                     kStreamIdentifierDataLength +
+                                     kHeaderLength;
+    MOZ_ASSERT(firstReadLength <= CompressedBufferLength());
+
+    rv = ReadAll(mCompressedBuffer.get(), firstReadLength, firstReadLength,
+                 aBytesReadOut);
+    if (NS_WARN_IF(NS_FAILED(rv)) || *aBytesReadOut == 0) { return rv; }
+
+    rv = ParseHeader(mCompressedBuffer.get(), kHeaderLength,
+                     &mNextChunkType, &mNextChunkDataLength);
+    if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+    if (NS_WARN_IF(mNextChunkType != StreamIdentifier ||
+                   mNextChunkDataLength != kStreamIdentifierDataLength)) {
+      return NS_ERROR_CORRUPTED_CONTENT;
+    }
+    size_t offset = kHeaderLength;
+
+    mNeedFirstStreamIdentifier = false;
+
+    size_t numRead;
+    size_t numWritten;
+    rv = ParseData(mUncompressedBuffer.get(), snappy::kBlockSize, mNextChunkType,
+                   &mCompressedBuffer[offset],
+                   mNextChunkDataLength, &numWritten, &numRead);
+    if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+    MOZ_ASSERT(numWritten == 0);
+    MOZ_ASSERT(numRead == mNextChunkDataLength);
+    offset += numRead;
+
+    rv = ParseHeader(&mCompressedBuffer[offset], *aBytesReadOut - offset,
+                     &mNextChunkType, &mNextChunkDataLength);
+    if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+
+    return NS_OK;
+  }
+
+  // We have no compressed data and we don't know how big the next chunk is.
+  // This happens when we get an EOF pause in the middle of a stream and also
+  // at the end of the stream.  Simply read the next header and return.  The
+  // chunk body will be read on the next entry into this method.
+  if (mNextChunkType == Unknown) {
+    rv = ReadAll(mCompressedBuffer.get(), kHeaderLength, kHeaderLength,
+                 aBytesReadOut);
+    if (NS_WARN_IF(NS_FAILED(rv)) || *aBytesReadOut == 0) { return rv; }
+
+    rv = ParseHeader(mCompressedBuffer.get(), kHeaderLength,
+                     &mNextChunkType, &mNextChunkDataLength);
+    if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+
+    return NS_OK;
+  }
+
+  // We have no decompressed data, but we do know the size of the next chunk.
+  // Read at least that much from the base stream.
+  uint32_t readLength = mNextChunkDataLength;
+  MOZ_ASSERT(readLength <= CompressedBufferLength());
+
+  // However, if there is enough data in the base stream, also read the next
+  // chunk header.  This helps optimize the stream by avoiding many small reads.
+  uint64_t avail;
+  rv = mBaseStream->Available(&avail);
+  if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+  if (avail >= (readLength + kHeaderLength)) {
+    readLength += kHeaderLength;
+    MOZ_ASSERT(readLength <= CompressedBufferLength());
+  }
+
+  rv = ReadAll(mCompressedBuffer.get(), readLength, mNextChunkDataLength,
+               aBytesReadOut);
+  if (NS_WARN_IF(NS_FAILED(rv)) || *aBytesReadOut == 0) { return rv; }
+
+  size_t numRead;
+  size_t numWritten;
+  rv = ParseData(mUncompressedBuffer.get(), snappy::kBlockSize, mNextChunkType,
+                 mCompressedBuffer.get(), mNextChunkDataLength,
+                 &numWritten, &numRead);
+  if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+  MOZ_ASSERT(numRead == mNextChunkDataLength);
+
+  mUncompressedBytes = numWritten;
+
+  // If we were unable to directly read the next chunk header, then clear
+  // our internal state.  We will have to perform a small read to get the
+  // header the next time we enter this method.
+  if (*aBytesReadOut <= mNextChunkDataLength) {
+    mNextChunkType = Unknown;
+    mNextChunkDataLength = 0;
+    return NS_OK;
+  }
+
+  // We got the next chunk header.  Parse it so that we are ready to for the
+  // next call into this method.
+  rv = ParseHeader(&mCompressedBuffer[numRead], *aBytesReadOut - numRead,
+                   &mNextChunkType, &mNextChunkDataLength);
+  if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+
+  return NS_OK;
+}
+
+nsresult
+SnappyUncompressInputStream::ReadAll(char* aBuf, uint32_t aCount,
+                                     uint32_t aMinValidCount,
+                                     uint32_t* aBytesReadOut)
+{
+  MOZ_ASSERT(aCount >= aMinValidCount);
+
+  *aBytesReadOut = 0;
+
+  if (!mBaseStream) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  uint32_t offset = 0;
+  while (aCount > 0) {
+    uint32_t bytesRead = 0;
+    nsresult rv = mBaseStream->Read(aBuf + offset, aCount, &bytesRead);
+    if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+
+    // EOF, but don't immediately return.  We need to validate min read bytes
+    // below.
+    if (bytesRead == 0) {
+      break;
+    }
+
+    *aBytesReadOut += bytesRead;
+    offset += bytesRead;
+    aCount -= bytesRead;
+  }
+
+  // Reading zero bytes is not an error.  Its the expected EOF condition.
+  // Only compare to the minimum valid count if we read at least one byte.
+  if (*aBytesReadOut != 0 && *aBytesReadOut < aMinValidCount) {
+    return NS_ERROR_CORRUPTED_CONTENT;
+  }
+
+  return NS_OK;
+}
+
+size_t
+SnappyUncompressInputStream::UncompressedLength() const
+{
+  MOZ_ASSERT(mNextByte <= mUncompressedBytes);
+  return mUncompressedBytes - mNextByte;
+}
+
+} // namespace mozilla
diff --git a/xpcom/io/SnappyUncompressInputStream.h b/xpcom/io/SnappyUncompressInputStream.h
new file mode 100644
index 000000000..0d24c0d11
--- /dev/null
+++ b/xpcom/io/SnappyUncompressInputStream.h
@@ -0,0 +1,90 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_SnappyUncompressInputStream_h__
+#define mozilla_SnappyUncompressInputStream_h__
+
+#include "mozilla/Attributes.h"
+#include "mozilla/UniquePtr.h"
+#include "nsCOMPtr.h"
+#include "nsIInputStream.h"
+#include "nsISupportsImpl.h"
+#include "SnappyFrameUtils.h"
+
+namespace mozilla {
+
+class SnappyUncompressInputStream final : public nsIInputStream
+                                        , protected detail::SnappyFrameUtils
+{
+public:
+  // Construct a new blocking stream to uncompress the given base stream.  The
+  // base stream must also be blocking.  The base stream does not have to be
+  // buffered.
+  explicit SnappyUncompressInputStream(nsIInputStream* aBaseStream);
+
+private:
+  virtual ~SnappyUncompressInputStream();
+
+  // Parse the next chunk of data.  This may populate mBuffer and set
+  // mBufferFillSize.  This should not be called when mBuffer already
+  // contains data.
+  nsresult ParseNextChunk(uint32_t* aBytesReadOut);
+
+  // Convenience routine to Read() from the base stream until we get
+  // the given number of bytes or reach EOF.
+  //
+  // aBuf           - The buffer to write the bytes into.
+  // aCount         - Max number of bytes to read. If the stream closes
+  //                  fewer bytes my be read.
+  // aMinValidCount - A minimum expected number of bytes.  If we find
+  //                  fewer than this many bytes, then return
+  //                  NS_ERROR_CORRUPTED_CONTENT.  If nothing was read due
+  //                  due to EOF (aBytesReadOut == 0), then NS_OK is returned.
+  // aBytesReadOut  - An out parameter indicating how many bytes were read.
+  nsresult ReadAll(char* aBuf, uint32_t aCount, uint32_t aMinValidCount,
+                   uint32_t* aBytesReadOut);
+
+  // Convenience routine to determine how many bytes of uncompressed data
+  // we currently have in our buffer.
+  size_t UncompressedLength() const;
+
+  nsCOMPtr<nsIInputStream> mBaseStream;
+
+  // Buffer to hold compressed data.  Must copy here since we need a large
+  // flat buffer to run the uncompress process on. Always the same length
+  // of SnappyFrameUtils::MaxCompressedBufferLength(snappy::kBlockSize)
+  // bytes long.
+  mozilla::UniquePtr<char[]> mCompressedBuffer;
+
+  // Buffer storing the resulting uncompressed data.  Exactly snappy::kBlockSize
+  // bytes long.
+  mozilla::UniquePtr<char[]> mUncompressedBuffer;
+
+  // Number of bytes of uncompressed data in mBuffer.
+  size_t mUncompressedBytes;
+
+  // Next byte of mBuffer to return in ReadSegments().  Must be less than
+  // mBufferFillSize
+  size_t mNextByte;
+
+  // Next chunk in the stream that has been parsed during read-ahead.
+  ChunkType mNextChunkType;
+
+  // Length of next chunk's length that has been determined during read-ahead.
+  size_t mNextChunkDataLength;
+
+  // The stream must begin with a StreamIdentifier chunk.  Are we still
+  // expecting it?
+  bool mNeedFirstStreamIdentifier;
+
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIINPUTSTREAM
+};
+
+} // namespace mozilla
+
+#endif // mozilla_SnappyUncompressInputStream_h__
diff --git a/xpcom/io/SpecialSystemDirectory.cpp b/xpcom/io/SpecialSystemDirectory.cpp
new file mode 100644
index 000000000..9ce8eb85b
--- /dev/null
+++ b/xpcom/io/SpecialSystemDirectory.cpp
@@ -0,0 +1,830 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "SpecialSystemDirectory.h"
+#include "nsString.h"
+#include "nsDependentString.h"
+#include "nsAutoPtr.h"
+
+#if defined(XP_WIN)
+
+#include <windows.h>
+#include <shlobj.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <direct.h>
+#include <shlobj.h>
+#include <knownfolders.h>
+#include <guiddef.h>
+#include "mozilla/WindowsVersion.h"
+
+using mozilla::IsWin7OrLater;
+
+#elif defined(XP_UNIX)
+
+#include <limits.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/param.h>
+#include "prenv.h"
+#if defined(MOZ_WIDGET_COCOA)
+#include "CocoaFileUtils.h"
+#endif
+
+#endif
+
+#ifndef MAXPATHLEN
+#ifdef PATH_MAX
+#define MAXPATHLEN PATH_MAX
+#elif defined(MAX_PATH)
+#define MAXPATHLEN MAX_PATH
+#elif defined(_MAX_PATH)
+#define MAXPATHLEN _MAX_PATH
+#elif defined(CCHMAXPATH)
+#define MAXPATHLEN CCHMAXPATH
+#else
+#define MAXPATHLEN 1024
+#endif
+#endif
+
+#ifdef XP_WIN
+typedef HRESULT (WINAPI* nsGetKnownFolderPath)(GUID& rfid,
+                                               DWORD dwFlags,
+                                               HANDLE hToken,
+                                               PWSTR* ppszPath);
+
+static nsGetKnownFolderPath gGetKnownFolderPath = nullptr;
+#endif
+
+void
+StartupSpecialSystemDirectory()
+{
+#if defined (XP_WIN)
+  // SHGetKnownFolderPath is only available on Windows Vista
+  // so that we need to use GetProcAddress to get the pointer.
+  HMODULE hShell32DLLInst = GetModuleHandleW(L"shell32.dll");
+  if (hShell32DLLInst) {
+    gGetKnownFolderPath = (nsGetKnownFolderPath)
+      GetProcAddress(hShell32DLLInst, "SHGetKnownFolderPath");
+  }
+#endif
+}
+
+#if defined (XP_WIN)
+
+static nsresult
+GetKnownFolder(GUID* aGuid, nsIFile** aFile)
+{
+  if (!aGuid || !gGetKnownFolderPath) {
+    return NS_ERROR_FAILURE;
+  }
+
+  PWSTR path = nullptr;
+  gGetKnownFolderPath(*aGuid, 0, nullptr, &path);
+
+  if (!path) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsresult rv = NS_NewLocalFile(nsDependentString(path),
+                                true,
+                                aFile);
+
+  CoTaskMemFree(path);
+  return rv;
+}
+
+static nsresult
+GetWindowsFolder(int aFolder, nsIFile** aFile)
+{
+  WCHAR path_orig[MAX_PATH + 3];
+  WCHAR* path = path_orig + 1;
+  HRESULT result = SHGetSpecialFolderPathW(nullptr, path, aFolder, true);
+
+  if (!SUCCEEDED(result)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Append the trailing slash
+  int len = wcslen(path);
+  if (len > 1 && path[len - 1] != L'\\') {
+    path[len]   = L'\\';
+    path[++len] = L'\0';
+  }
+
+  return NS_NewLocalFile(nsDependentString(path, len), true, aFile);
+}
+
+__inline HRESULT
+SHLoadLibraryFromKnownFolder(REFKNOWNFOLDERID aFolderId, DWORD aMode,
+                             REFIID riid, void** ppv)
+{
+  *ppv = nullptr;
+  IShellLibrary* plib;
+  HRESULT hr = CoCreateInstance(CLSID_ShellLibrary, nullptr,
+                                CLSCTX_INPROC_SERVER,
+                                IID_PPV_ARGS(&plib));
+  if (SUCCEEDED(hr)) {
+    hr = plib->LoadLibraryFromKnownFolder(aFolderId, aMode);
+    if (SUCCEEDED(hr)) {
+      hr = plib->QueryInterface(riid, ppv);
+    }
+    plib->Release();
+  }
+  return hr;
+}
+
+/*
+ * Check to see if we're on Win7 and up, and if so, returns the default
+ * save-to location for the Windows Library passed in through aFolderId.
+ * Otherwise falls back on pre-win7 GetWindowsFolder.
+ */
+static nsresult
+GetLibrarySaveToPath(int aFallbackFolderId, REFKNOWNFOLDERID aFolderId,
+                     nsIFile** aFile)
+{
+  // Skip off checking for library support if the os is Vista or lower.
+  if (!IsWin7OrLater()) {
+    return GetWindowsFolder(aFallbackFolderId, aFile);
+  }
+
+  RefPtr<IShellLibrary> shellLib;
+  RefPtr<IShellItem> savePath;
+  HRESULT hr =
+    SHLoadLibraryFromKnownFolder(aFolderId, STGM_READ,
+                                 IID_IShellLibrary, getter_AddRefs(shellLib));
+
+  if (shellLib &&
+      SUCCEEDED(shellLib->GetDefaultSaveFolder(DSFT_DETECT, IID_IShellItem,
+                                               getter_AddRefs(savePath)))) {
+    wchar_t* str = nullptr;
+    if (SUCCEEDED(savePath->GetDisplayName(SIGDN_FILESYSPATH, &str))) {
+      nsAutoString path;
+      path.Assign(str);
+      path.Append('\\');
+      nsresult rv =
+        NS_NewLocalFile(path, false, aFile);
+      CoTaskMemFree(str);
+      return rv;
+    }
+  }
+
+  return GetWindowsFolder(aFallbackFolderId, aFile);
+}
+
+/**
+ * Provides a fallback for getting the path to APPDATA or LOCALAPPDATA by
+ * querying the registry when the call to SHGetSpecialFolderPathW is unable to
+ * provide these paths (Bug 513958).
+ */
+static nsresult
+GetRegWindowsAppDataFolder(bool aLocal, nsIFile** aFile)
+{
+  HKEY key;
+  NS_NAMED_LITERAL_STRING(keyName,
+    "Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\Shell Folders");
+  DWORD res = ::RegOpenKeyExW(HKEY_CURRENT_USER, keyName.get(), 0, KEY_READ,
+                              &key);
+  if (res != ERROR_SUCCESS) {
+    return NS_ERROR_FAILURE;
+  }
+
+  WCHAR path[MAX_PATH + 2];
+  DWORD type, size;
+  res = RegQueryValueExW(key, (aLocal ? L"Local AppData" : L"AppData"),
+                         nullptr, &type, (LPBYTE)&path, &size);
+  ::RegCloseKey(key);
+  // The call to RegQueryValueExW must succeed, the type must be REG_SZ, the
+  // buffer size must not equal 0, and the buffer size be a multiple of 2.
+  if (res != ERROR_SUCCESS || type != REG_SZ || size == 0 || size % 2 != 0) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Append the trailing slash
+  int len = wcslen(path);
+  if (len > 1 && path[len - 1] != L'\\') {
+    path[len]   = L'\\';
+    path[++len] = L'\0';
+  }
+
+  return NS_NewLocalFile(nsDependentString(path, len), true, aFile);
+}
+
+#endif // XP_WIN
+
+#if defined(XP_UNIX)
+static nsresult
+GetUnixHomeDir(nsIFile** aFile)
+{
+#if defined(ANDROID)
+  // XXX no home dir on android; maybe we should return the sdcard if present?
+  return NS_ERROR_FAILURE;
+#else
+  return NS_NewNativeLocalFile(nsDependentCString(PR_GetEnv("HOME")),
+                               true, aFile);
+#endif
+}
+
+/*
+  The following license applies to the xdg_user_dir_lookup function:
+
+  Copyright (c) 2007 Red Hat, Inc.
+
+  Permission is hereby granted, free of charge, to any person
+  obtaining a copy of this software and associated documentation files
+  (the "Software"), to deal in the Software without restriction,
+  including without limitation the rights to use, copy, modify, merge,
+  publish, distribute, sublicense, and/or sell copies of the Software,
+  and to permit persons to whom the Software is furnished to do so,
+  subject to the following conditions:
+
+  The above copyright notice and this permission notice shall be
+  included in all copies or substantial portions of the Software.
+
+  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+  BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+  SOFTWARE.
+*/
+
+static char*
+xdg_user_dir_lookup(const char* aType)
+{
+  FILE* file;
+  char* home_dir;
+  char* config_home;
+  char* config_file;
+  char buffer[512];
+  char* user_dir;
+  char* p;
+  char* d;
+  int len;
+  int relative;
+
+  home_dir = getenv("HOME");
+
+  if (!home_dir) {
+    goto error;
+  }
+
+  config_home = getenv("XDG_CONFIG_HOME");
+  if (!config_home || config_home[0] == 0) {
+    config_file = (char*)malloc(strlen(home_dir) +
+                                strlen("/.config/user-dirs.dirs") + 1);
+    if (!config_file) {
+      goto error;
+    }
+
+    strcpy(config_file, home_dir);
+    strcat(config_file, "/.config/user-dirs.dirs");
+  } else {
+    config_file = (char*)malloc(strlen(config_home) +
+                                strlen("/user-dirs.dirs") + 1);
+    if (!config_file) {
+      goto error;
+    }
+
+    strcpy(config_file, config_home);
+    strcat(config_file, "/user-dirs.dirs");
+  }
+
+  file = fopen(config_file, "r");
+  free(config_file);
+  if (!file) {
+    goto error;
+  }
+
+  user_dir = nullptr;
+  while (fgets(buffer, sizeof(buffer), file)) {
+    /* Remove newline at end */
+    len = strlen(buffer);
+    if (len > 0 && buffer[len - 1] == '\n') {
+      buffer[len - 1] = 0;
+    }
+
+    p = buffer;
+    while (*p == ' ' || *p == '\t') {
+      p++;
+    }
+
+    if (strncmp(p, "XDG_", 4) != 0) {
+      continue;
+    }
+    p += 4;
+    if (strncmp(p, aType, strlen(aType)) != 0) {
+      continue;
+    }
+    p += strlen(aType);
+    if (strncmp(p, "_DIR", 4) != 0) {
+      continue;
+    }
+    p += 4;
+
+    while (*p == ' ' || *p == '\t') {
+      p++;
+    }
+
+    if (*p != '=') {
+      continue;
+    }
+    p++;
+
+    while (*p == ' ' || *p == '\t') {
+      p++;
+    }
+
+    if (*p != '"') {
+      continue;
+    }
+    p++;
+
+    relative = 0;
+    if (strncmp(p, "$HOME/", 6) == 0) {
+      p += 6;
+      relative = 1;
+    } else if (*p != '/') {
+      continue;
+    }
+
+    if (relative) {
+      user_dir = (char*)malloc(strlen(home_dir) + 1 + strlen(p) + 1);
+      if (!user_dir) {
+        goto error2;
+      }
+
+      strcpy(user_dir, home_dir);
+      strcat(user_dir, "/");
+    } else {
+      user_dir = (char*)malloc(strlen(p) + 1);
+      if (!user_dir) {
+        goto error2;
+      }
+
+      *user_dir = 0;
+    }
+
+    d = user_dir + strlen(user_dir);
+    while (*p && *p != '"') {
+      if ((*p == '\\') && (*(p + 1) != 0)) {
+        p++;
+      }
+      *d++ = *p++;
+    }
+    *d = 0;
+  }
+error2:
+  fclose(file);
+
+  if (user_dir) {
+    return user_dir;
+  }
+
+error:
+  return nullptr;
+}
+
+static const char xdg_user_dirs[] =
+  "DESKTOP\0"
+  "DOCUMENTS\0"
+  "DOWNLOAD\0"
+  "MUSIC\0"
+  "PICTURES\0"
+  "PUBLICSHARE\0"
+  "TEMPLATES\0"
+  "VIDEOS";
+
+static const uint8_t xdg_user_dir_offsets[] = {
+  0,
+  8,
+  18,
+  27,
+  33,
+  42,
+  54,
+  64
+};
+
+static nsresult
+GetUnixXDGUserDirectory(SystemDirectories aSystemDirectory,
+                        nsIFile** aFile)
+{
+  char* dir = xdg_user_dir_lookup(
+    xdg_user_dirs + xdg_user_dir_offsets[aSystemDirectory - Unix_XDG_Desktop]);
+
+  nsresult rv;
+  nsCOMPtr<nsIFile> file;
+  if (dir) {
+    rv = NS_NewNativeLocalFile(nsDependentCString(dir), true,
+                               getter_AddRefs(file));
+    free(dir);
+  } else if (Unix_XDG_Desktop == aSystemDirectory) {
+    // for the XDG desktop dir, fall back to HOME/Desktop
+    // (for historical compatibility)
+    rv = GetUnixHomeDir(getter_AddRefs(file));
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    rv = file->AppendNative(NS_LITERAL_CSTRING("Desktop"));
+  } else {
+    // no fallback for the other XDG dirs
+    rv = NS_ERROR_FAILURE;
+  }
+
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  bool exists;
+  rv = file->Exists(&exists);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (!exists) {
+    rv = file->Create(nsIFile::DIRECTORY_TYPE, 0755);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+  }
+
+  *aFile = nullptr;
+  file.swap(*aFile);
+
+  return NS_OK;
+}
+#endif
+
+nsresult
+GetSpecialSystemDirectory(SystemDirectories aSystemSystemDirectory,
+                          nsIFile** aFile)
+{
+#if defined(XP_WIN)
+  WCHAR path[MAX_PATH];
+#else
+  char path[MAXPATHLEN];
+#endif
+
+  switch (aSystemSystemDirectory) {
+    case OS_CurrentWorkingDirectory:
+#if defined(XP_WIN)
+      if (!_wgetcwd(path, MAX_PATH)) {
+        return NS_ERROR_FAILURE;
+      }
+      return NS_NewLocalFile(nsDependentString(path),
+                             true,
+                             aFile);
+#else
+      if (!getcwd(path, MAXPATHLEN)) {
+        return NS_ERROR_FAILURE;
+      }
+#endif
+
+#if !defined(XP_WIN)
+      return NS_NewNativeLocalFile(nsDependentCString(path),
+                                   true,
+                                   aFile);
+#endif
+
+    case OS_DriveDirectory:
+#if defined (XP_WIN)
+    {
+      int32_t len = ::GetWindowsDirectoryW(path, MAX_PATH);
+      if (len == 0) {
+        break;
+      }
+      if (path[1] == char16_t(':') && path[2] == char16_t('\\')) {
+        path[3] = 0;
+      }
+
+      return NS_NewLocalFile(nsDependentString(path),
+                             true,
+                             aFile);
+    }
+#else
+    return NS_NewNativeLocalFile(nsDependentCString("/"),
+                                 true,
+                                 aFile);
+
+#endif
+
+    case OS_TemporaryDirectory:
+#if defined (XP_WIN)
+    {
+      DWORD len = ::GetTempPathW(MAX_PATH, path);
+      if (len == 0) {
+        break;
+      }
+      return NS_NewLocalFile(nsDependentString(path, len),
+                             true,
+                             aFile);
+    }
+#elif defined(MOZ_WIDGET_COCOA)
+    {
+      return GetOSXFolderType(kUserDomain, kTemporaryFolderType, aFile);
+    }
+
+#elif defined(XP_UNIX)
+    {
+      static const char* tPath = nullptr;
+      if (!tPath) {
+        tPath = PR_GetEnv("TMPDIR");
+        if (!tPath || !*tPath) {
+          tPath = PR_GetEnv("TMP");
+          if (!tPath || !*tPath) {
+            tPath = PR_GetEnv("TEMP");
+            if (!tPath || !*tPath) {
+              tPath = "/tmp/";
+            }
+          }
+        }
+      }
+      return NS_NewNativeLocalFile(nsDependentCString(tPath),
+                                   true,
+                                   aFile);
+    }
+#else
+    break;
+#endif
+#if defined (XP_WIN)
+    case Win_SystemDirectory: {
+      int32_t len = ::GetSystemDirectoryW(path, MAX_PATH);
+
+      // Need enough space to add the trailing backslash
+      if (!len || len > MAX_PATH - 2) {
+        break;
+      }
+      path[len]   = L'\\';
+      path[++len] = L'\0';
+
+      return NS_NewLocalFile(nsDependentString(path, len),
+                             true,
+                             aFile);
+    }
+
+    case Win_WindowsDirectory: {
+      int32_t len = ::GetWindowsDirectoryW(path, MAX_PATH);
+
+      // Need enough space to add the trailing backslash
+      if (!len || len > MAX_PATH - 2) {
+        break;
+      }
+
+      path[len]   = L'\\';
+      path[++len] = L'\0';
+
+      return NS_NewLocalFile(nsDependentString(path, len),
+                             true,
+                             aFile);
+    }
+
+    case Win_ProgramFiles: {
+      return GetWindowsFolder(CSIDL_PROGRAM_FILES, aFile);
+    }
+
+    case Win_HomeDirectory: {
+      nsresult rv = GetWindowsFolder(CSIDL_PROFILE, aFile);
+      if (NS_SUCCEEDED(rv)) {
+        return rv;
+      }
+
+      int32_t len;
+      if ((len = ::GetEnvironmentVariableW(L"HOME", path, MAX_PATH)) > 0) {
+        // Need enough space to add the trailing backslash
+        if (len > MAX_PATH - 2) {
+          break;
+        }
+
+        path[len]   = L'\\';
+        path[++len] = L'\0';
+
+        rv = NS_NewLocalFile(nsDependentString(path, len),
+                             true,
+                             aFile);
+        if (NS_SUCCEEDED(rv)) {
+          return rv;
+        }
+      }
+
+      len = ::GetEnvironmentVariableW(L"HOMEDRIVE", path, MAX_PATH);
+      if (0 < len && len < MAX_PATH) {
+        WCHAR temp[MAX_PATH];
+        DWORD len2 = ::GetEnvironmentVariableW(L"HOMEPATH", temp, MAX_PATH);
+        if (0 < len2 && len + len2 < MAX_PATH) {
+          wcsncat(path, temp, len2);
+        }
+
+        len = wcslen(path);
+
+        // Need enough space to add the trailing backslash
+        if (len > MAX_PATH - 2) {
+          break;
+        }
+
+        path[len]   = L'\\';
+        path[++len] = L'\0';
+
+        return NS_NewLocalFile(nsDependentString(path, len),
+                               true,
+                               aFile);
+      }
+    }
+    case Win_Desktop: {
+      return GetWindowsFolder(CSIDL_DESKTOP, aFile);
+    }
+    case Win_Programs: {
+      return GetWindowsFolder(CSIDL_PROGRAMS, aFile);
+    }
+
+    case Win_Downloads: {
+      // Defined in KnownFolders.h.
+      GUID folderid_downloads = {
+        0x374de290, 0x123f, 0x4565,
+        { 0x91, 0x64, 0x39, 0xc4, 0x92, 0x5e, 0x46, 0x7b }
+      };
+      nsresult rv = GetKnownFolder(&folderid_downloads, aFile);
+      // On WinXP, there is no downloads folder, default
+      // to 'Desktop'.
+      if (NS_ERROR_FAILURE == rv) {
+        rv = GetWindowsFolder(CSIDL_DESKTOP, aFile);
+      }
+      return rv;
+    }
+
+    case Win_Controls: {
+      return GetWindowsFolder(CSIDL_CONTROLS, aFile);
+    }
+    case Win_Printers: {
+      return GetWindowsFolder(CSIDL_PRINTERS, aFile);
+    }
+    case Win_Personal: {
+      return GetWindowsFolder(CSIDL_PERSONAL, aFile);
+    }
+    case Win_Favorites: {
+      return GetWindowsFolder(CSIDL_FAVORITES, aFile);
+    }
+    case Win_Startup: {
+      return GetWindowsFolder(CSIDL_STARTUP, aFile);
+    }
+    case Win_Recent: {
+      return GetWindowsFolder(CSIDL_RECENT, aFile);
+    }
+    case Win_Sendto: {
+      return GetWindowsFolder(CSIDL_SENDTO, aFile);
+    }
+    case Win_Bitbucket: {
+      return GetWindowsFolder(CSIDL_BITBUCKET, aFile);
+    }
+    case Win_Startmenu: {
+      return GetWindowsFolder(CSIDL_STARTMENU, aFile);
+    }
+    case Win_Desktopdirectory: {
+      return GetWindowsFolder(CSIDL_DESKTOPDIRECTORY, aFile);
+    }
+    case Win_Drives: {
+      return GetWindowsFolder(CSIDL_DRIVES, aFile);
+    }
+    case Win_Network: {
+      return GetWindowsFolder(CSIDL_NETWORK, aFile);
+    }
+    case Win_Nethood: {
+      return GetWindowsFolder(CSIDL_NETHOOD, aFile);
+    }
+    case Win_Fonts: {
+      return GetWindowsFolder(CSIDL_FONTS, aFile);
+    }
+    case Win_Templates: {
+      return GetWindowsFolder(CSIDL_TEMPLATES, aFile);
+    }
+    case Win_Common_Startmenu: {
+      return GetWindowsFolder(CSIDL_COMMON_STARTMENU, aFile);
+    }
+    case Win_Common_Programs: {
+      return GetWindowsFolder(CSIDL_COMMON_PROGRAMS, aFile);
+    }
+    case Win_Common_Startup: {
+      return GetWindowsFolder(CSIDL_COMMON_STARTUP, aFile);
+    }
+    case Win_Common_Desktopdirectory: {
+      return GetWindowsFolder(CSIDL_COMMON_DESKTOPDIRECTORY, aFile);
+    }
+    case Win_Common_AppData: {
+      return GetWindowsFolder(CSIDL_COMMON_APPDATA, aFile);
+    }
+    case Win_Printhood: {
+      return GetWindowsFolder(CSIDL_PRINTHOOD, aFile);
+    }
+    case Win_Cookies: {
+      return GetWindowsFolder(CSIDL_COOKIES, aFile);
+    }
+    case Win_Appdata: {
+      nsresult rv = GetWindowsFolder(CSIDL_APPDATA, aFile);
+      if (NS_FAILED(rv)) {
+        rv = GetRegWindowsAppDataFolder(false, aFile);
+      }
+      return rv;
+    }
+    case Win_LocalAppdata: {
+      nsresult rv = GetWindowsFolder(CSIDL_LOCAL_APPDATA, aFile);
+      if (NS_FAILED(rv)) {
+        rv = GetRegWindowsAppDataFolder(true, aFile);
+      }
+      return rv;
+    }
+#if defined(MOZ_CONTENT_SANDBOX)
+    case Win_LocalAppdataLow: {
+      // This should only really fail on versions pre-Vista, in which case this
+      // shouldn't have been used in the first place.
+      GUID localAppDataLowGuid = FOLDERID_LocalAppDataLow;
+      return GetKnownFolder(&localAppDataLowGuid, aFile);
+    }
+#endif
+    case Win_Documents: {
+      return GetLibrarySaveToPath(CSIDL_MYDOCUMENTS,
+                                  FOLDERID_DocumentsLibrary,
+                                  aFile);
+    }
+    case Win_Pictures: {
+      return GetLibrarySaveToPath(CSIDL_MYPICTURES,
+                                  FOLDERID_PicturesLibrary,
+                                  aFile);
+    }
+    case Win_Music: {
+      return GetLibrarySaveToPath(CSIDL_MYMUSIC,
+                                  FOLDERID_MusicLibrary,
+                                  aFile);
+    }
+    case Win_Videos: {
+      return GetLibrarySaveToPath(CSIDL_MYVIDEO,
+                                  FOLDERID_VideosLibrary,
+                                  aFile);
+    }
+#endif  // XP_WIN
+
+#if defined(XP_UNIX)
+    case Unix_LocalDirectory:
+      return NS_NewNativeLocalFile(nsDependentCString("/usr/local/netscape/"),
+                                   true,
+                                   aFile);
+    case Unix_LibDirectory:
+      return NS_NewNativeLocalFile(nsDependentCString("/usr/local/lib/netscape/"),
+                                   true,
+                                   aFile);
+
+    case Unix_HomeDirectory:
+      return GetUnixHomeDir(aFile);
+
+    case Unix_XDG_Desktop:
+    case Unix_XDG_Documents:
+    case Unix_XDG_Download:
+    case Unix_XDG_Music:
+    case Unix_XDG_Pictures:
+    case Unix_XDG_PublicShare:
+    case Unix_XDG_Templates:
+    case Unix_XDG_Videos:
+      return GetUnixXDGUserDirectory(aSystemSystemDirectory, aFile);
+#endif
+
+    default:
+      break;
+  }
+  return NS_ERROR_NOT_AVAILABLE;
+}
+
+#if defined (MOZ_WIDGET_COCOA)
+nsresult
+GetOSXFolderType(short aDomain, OSType aFolderType, nsIFile** aLocalFile)
+{
+  nsresult rv = NS_ERROR_FAILURE;
+
+  if (aFolderType == kTemporaryFolderType) {
+    NS_NewLocalFile(EmptyString(), true, aLocalFile);
+    nsCOMPtr<nsILocalFileMac> localMacFile(do_QueryInterface(*aLocalFile));
+    if (localMacFile) {
+      rv = localMacFile->InitWithCFURL(
+             CocoaFileUtils::GetTemporaryFolderCFURLRef());
+    }
+    return rv;
+  }
+
+  OSErr err;
+  FSRef fsRef;
+  err = ::FSFindFolder(aDomain, aFolderType, kCreateFolder, &fsRef);
+  if (err == noErr) {
+    NS_NewLocalFile(EmptyString(), true, aLocalFile);
+    nsCOMPtr<nsILocalFileMac> localMacFile(do_QueryInterface(*aLocalFile));
+    if (localMacFile) {
+      rv = localMacFile->InitWithFSRef(&fsRef);
+    }
+  }
+  return rv;
+}
+#endif
+
diff --git a/xpcom/io/SpecialSystemDirectory.h b/xpcom/io/SpecialSystemDirectory.h
new file mode 100644
index 000000000..dd3d88379
--- /dev/null
+++ b/xpcom/io/SpecialSystemDirectory.h
@@ -0,0 +1,107 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef _SPECIALSYSTEMDIRECTORY_H_
+#define _SPECIALSYSTEMDIRECTORY_H_
+
+#include "nscore.h"
+#include "nsIFile.h"
+
+#ifdef MOZ_WIDGET_COCOA
+#include <Carbon/Carbon.h>
+#include "nsILocalFileMac.h"
+#include "prenv.h"
+#endif
+
+extern void StartupSpecialSystemDirectory();
+
+
+enum SystemDirectories {
+  OS_DriveDirectory         =   1,
+  OS_TemporaryDirectory     =   2,
+  OS_CurrentProcessDirectory =  3,
+  OS_CurrentWorkingDirectory =  4,
+  XPCOM_CurrentProcessComponentDirectory = 5,
+  XPCOM_CurrentProcessComponentRegistry =  6,
+
+  Moz_BinDirectory          =   100 ,
+  Mac_SystemDirectory       =   101,
+  Mac_DesktopDirectory      =   102,
+  Mac_TrashDirectory        =   103,
+  Mac_StartupDirectory      =   104,
+  Mac_ShutdownDirectory     =   105,
+  Mac_AppleMenuDirectory    =   106,
+  Mac_ControlPanelDirectory =   107,
+  Mac_ExtensionDirectory    =   108,
+  Mac_FontsDirectory        =   109,
+  Mac_ClassicPreferencesDirectory =   110,
+  Mac_DocumentsDirectory          =   111,
+  Mac_InternetSearchDirectory     =   112,
+  Mac_DefaultDownloadDirectory    =   113,
+  Mac_UserLibDirectory      =   114,
+  Mac_PreferencesDirectory  =   115,
+
+  Win_SystemDirectory       =   201,
+  Win_WindowsDirectory      =   202,
+  Win_HomeDirectory         =   203,
+  Win_Desktop               =   204,
+  Win_Programs              =   205,
+  Win_Controls              =   206,
+  Win_Printers              =   207,
+  Win_Personal              =   208,
+  Win_Favorites             =   209,
+  Win_Startup               =   210,
+  Win_Recent                =   211,
+  Win_Sendto                =   212,
+  Win_Bitbucket             =   213,
+  Win_Startmenu             =   214,
+  Win_Desktopdirectory      =   215,
+  Win_Drives                =   216,
+  Win_Network               =   217,
+  Win_Nethood               =   218,
+  Win_Fonts                 =   219,
+  Win_Templates             =   220,
+  Win_Common_Startmenu      =   221,
+  Win_Common_Programs       =   222,
+  Win_Common_Startup        =   223,
+  Win_Common_Desktopdirectory = 224,
+  Win_Appdata               =   225,
+  Win_Printhood             =   226,
+  Win_Cookies               =   227,
+  Win_LocalAppdata          =   228,
+  Win_ProgramFiles          =   229,
+  Win_Downloads             =   230,
+  Win_Common_AppData        =   231,
+  Win_Documents             =   232,
+  Win_Pictures              =   233,
+  Win_Music                 =   234,
+  Win_Videos                =   235,
+#if defined(MOZ_CONTENT_SANDBOX)
+  Win_LocalAppdataLow       =   236,
+#endif
+
+  Unix_LocalDirectory       =   301,
+  Unix_LibDirectory         =   302,
+  Unix_HomeDirectory        =   303,
+  Unix_XDG_Desktop          =   304,
+  Unix_XDG_Documents        =   305,
+  Unix_XDG_Download         =   306,
+  Unix_XDG_Music            =   307,
+  Unix_XDG_Pictures         =   308,
+  Unix_XDG_PublicShare      =   309,
+  Unix_XDG_Templates        =   310,
+  Unix_XDG_Videos           =   311
+};
+
+nsresult
+GetSpecialSystemDirectory(SystemDirectories aSystemSystemDirectory,
+                          nsIFile** aFile);
+#ifdef MOZ_WIDGET_COCOA
+nsresult
+GetOSXFolderType(short aDomain, OSType aFolderType, nsIFile** aLocalFile);
+#endif
+
+#endif
diff --git a/xpcom/io/crc32c.c b/xpcom/io/crc32c.c
new file mode 100644
index 000000000..3494945c0
--- /dev/null
+++ b/xpcom/io/crc32c.c
@@ -0,0 +1,154 @@
+/*
+ * Based on file found here:
+ *
+ *   https://svnweb.freebsd.org/base/stable/10/sys/libkern/crc32.c?revision=256281
+ */
+
+/*-
+ *  COPYRIGHT (C) 1986 Gary S. Brown.  You may use this program, or
+ *  code or tables extracted from it, as desired without restriction.
+ */
+
+/*
+ *  First, the polynomial itself and its table of feedback terms.  The
+ *  polynomial is
+ *  X^32+X^26+X^23+X^22+X^16+X^12+X^11+X^10+X^8+X^7+X^5+X^4+X^2+X^1+X^0
+ *
+ *  Note that we take it "backwards" and put the highest-order term in
+ *  the lowest-order bit.  The X^32 term is "implied"; the LSB is the
+ *  X^31 term, etc.  The X^0 term (usually shown as "+1") results in
+ *  the MSB being 1
+ *
+ *  Note that the usual hardware shift register implementation, which
+ *  is what we're using (we're merely optimizing it by doing eight-bit
+ *  chunks at a time) shifts bits into the lowest-order term.  In our
+ *  implementation, that means shifting towards the right.  Why do we
+ *  do it this way?  Because the calculated CRC must be transmitted in
+ *  order from highest-order term to lowest-order term.  UARTs transmit
+ *  characters in order from LSB to MSB.  By storing the CRC this way
+ *  we hand it to the UART in the order low-byte to high-byte; the UART
+ *  sends each low-bit to hight-bit; and the result is transmission bit
+ *  by bit from highest- to lowest-order term without requiring any bit
+ *  shuffling on our part.  Reception works similarly
+ *
+ *  The feedback terms table consists of 256, 32-bit entries.  Notes
+ *
+ *      The table can be generated at runtime if desired; code to do so
+ *      is shown later.  It might not be obvious, but the feedback
+ *      terms simply represent the results of eight shift/xor opera
+ *      tions for all combinations of data and CRC register values
+ *
+ *      The values must be right-shifted by eight bits by the "updcrc
+ *      logic; the shift must be unsigned (bring in zeroes).  On some
+ *      hardware you could probably optimize the shift in assembler by
+ *      using byte-swap instructions
+ *      polynomial $edb88320
+ *
+ *
+ * CRC32 code derived from work by Gary S. Brown.
+ */
+
+#include "crc32c.h"
+
+/* CRC32C routines, these use a different polynomial */
+/*****************************************************************/
+/*                                                               */
+/* CRC LOOKUP TABLE                                              */
+/* ================                                              */
+/* The following CRC lookup table was generated automagically    */
+/* by the Rocksoft^tm Model CRC Algorithm Table Generation       */
+/* Program V1.0 using the following model parameters:            */
+/*                                                               */
+/*    Width   : 4 bytes.                                         */
+/*    Poly    : 0x1EDC6F41L                                      */
+/*    Reverse : TRUE.                                            */
+/*                                                               */
+/* For more information on the Rocksoft^tm Model CRC Algorithm,  */
+/* see the document titled "A Painless Guide to CRC Error        */
+/* Detection Algorithms" by Ross Williams                        */
+/* (ross@guest.adelaide.edu.au.). This document is likely to be  */
+/* in the FTP archive "ftp.adelaide.edu.au/pub/rocksoft".        */
+/*                                                               */
+/*****************************************************************/
+
+static const uint32_t crc32Table[256] = {
+	0x00000000L, 0xF26B8303L, 0xE13B70F7L, 0x1350F3F4L,
+	0xC79A971FL, 0x35F1141CL, 0x26A1E7E8L, 0xD4CA64EBL,
+	0x8AD958CFL, 0x78B2DBCCL, 0x6BE22838L, 0x9989AB3BL,
+	0x4D43CFD0L, 0xBF284CD3L, 0xAC78BF27L, 0x5E133C24L,
+	0x105EC76FL, 0xE235446CL, 0xF165B798L, 0x030E349BL,
+	0xD7C45070L, 0x25AFD373L, 0x36FF2087L, 0xC494A384L,
+	0x9A879FA0L, 0x68EC1CA3L, 0x7BBCEF57L, 0x89D76C54L,
+	0x5D1D08BFL, 0xAF768BBCL, 0xBC267848L, 0x4E4DFB4BL,
+	0x20BD8EDEL, 0xD2D60DDDL, 0xC186FE29L, 0x33ED7D2AL,
+	0xE72719C1L, 0x154C9AC2L, 0x061C6936L, 0xF477EA35L,
+	0xAA64D611L, 0x580F5512L, 0x4B5FA6E6L, 0xB93425E5L,
+	0x6DFE410EL, 0x9F95C20DL, 0x8CC531F9L, 0x7EAEB2FAL,
+	0x30E349B1L, 0xC288CAB2L, 0xD1D83946L, 0x23B3BA45L,
+	0xF779DEAEL, 0x05125DADL, 0x1642AE59L, 0xE4292D5AL,
+	0xBA3A117EL, 0x4851927DL, 0x5B016189L, 0xA96AE28AL,
+	0x7DA08661L, 0x8FCB0562L, 0x9C9BF696L, 0x6EF07595L,
+	0x417B1DBCL, 0xB3109EBFL, 0xA0406D4BL, 0x522BEE48L,
+	0x86E18AA3L, 0x748A09A0L, 0x67DAFA54L, 0x95B17957L,
+	0xCBA24573L, 0x39C9C670L, 0x2A993584L, 0xD8F2B687L,
+	0x0C38D26CL, 0xFE53516FL, 0xED03A29BL, 0x1F682198L,
+	0x5125DAD3L, 0xA34E59D0L, 0xB01EAA24L, 0x42752927L,
+	0x96BF4DCCL, 0x64D4CECFL, 0x77843D3BL, 0x85EFBE38L,
+	0xDBFC821CL, 0x2997011FL, 0x3AC7F2EBL, 0xC8AC71E8L,
+	0x1C661503L, 0xEE0D9600L, 0xFD5D65F4L, 0x0F36E6F7L,
+	0x61C69362L, 0x93AD1061L, 0x80FDE395L, 0x72966096L,
+	0xA65C047DL, 0x5437877EL, 0x4767748AL, 0xB50CF789L,
+	0xEB1FCBADL, 0x197448AEL, 0x0A24BB5AL, 0xF84F3859L,
+	0x2C855CB2L, 0xDEEEDFB1L, 0xCDBE2C45L, 0x3FD5AF46L,
+	0x7198540DL, 0x83F3D70EL, 0x90A324FAL, 0x62C8A7F9L,
+	0xB602C312L, 0x44694011L, 0x5739B3E5L, 0xA55230E6L,
+	0xFB410CC2L, 0x092A8FC1L, 0x1A7A7C35L, 0xE811FF36L,
+	0x3CDB9BDDL, 0xCEB018DEL, 0xDDE0EB2AL, 0x2F8B6829L,
+	0x82F63B78L, 0x709DB87BL, 0x63CD4B8FL, 0x91A6C88CL,
+	0x456CAC67L, 0xB7072F64L, 0xA457DC90L, 0x563C5F93L,
+	0x082F63B7L, 0xFA44E0B4L, 0xE9141340L, 0x1B7F9043L,
+	0xCFB5F4A8L, 0x3DDE77ABL, 0x2E8E845FL, 0xDCE5075CL,
+	0x92A8FC17L, 0x60C37F14L, 0x73938CE0L, 0x81F80FE3L,
+	0x55326B08L, 0xA759E80BL, 0xB4091BFFL, 0x466298FCL,
+	0x1871A4D8L, 0xEA1A27DBL, 0xF94AD42FL, 0x0B21572CL,
+	0xDFEB33C7L, 0x2D80B0C4L, 0x3ED04330L, 0xCCBBC033L,
+	0xA24BB5A6L, 0x502036A5L, 0x4370C551L, 0xB11B4652L,
+	0x65D122B9L, 0x97BAA1BAL, 0x84EA524EL, 0x7681D14DL,
+	0x2892ED69L, 0xDAF96E6AL, 0xC9A99D9EL, 0x3BC21E9DL,
+	0xEF087A76L, 0x1D63F975L, 0x0E330A81L, 0xFC588982L,
+	0xB21572C9L, 0x407EF1CAL, 0x532E023EL, 0xA145813DL,
+	0x758FE5D6L, 0x87E466D5L, 0x94B49521L, 0x66DF1622L,
+	0x38CC2A06L, 0xCAA7A905L, 0xD9F75AF1L, 0x2B9CD9F2L,
+	0xFF56BD19L, 0x0D3D3E1AL, 0x1E6DCDEEL, 0xEC064EEDL,
+	0xC38D26C4L, 0x31E6A5C7L, 0x22B65633L, 0xD0DDD530L,
+	0x0417B1DBL, 0xF67C32D8L, 0xE52CC12CL, 0x1747422FL,
+	0x49547E0BL, 0xBB3FFD08L, 0xA86F0EFCL, 0x5A048DFFL,
+	0x8ECEE914L, 0x7CA56A17L, 0x6FF599E3L, 0x9D9E1AE0L,
+	0xD3D3E1ABL, 0x21B862A8L, 0x32E8915CL, 0xC083125FL,
+	0x144976B4L, 0xE622F5B7L, 0xF5720643L, 0x07198540L,
+	0x590AB964L, 0xAB613A67L, 0xB831C993L, 0x4A5A4A90L,
+	0x9E902E7BL, 0x6CFBAD78L, 0x7FAB5E8CL, 0x8DC0DD8FL,
+	0xE330A81AL, 0x115B2B19L, 0x020BD8EDL, 0xF0605BEEL,
+	0x24AA3F05L, 0xD6C1BC06L, 0xC5914FF2L, 0x37FACCF1L,
+	0x69E9F0D5L, 0x9B8273D6L, 0x88D28022L, 0x7AB90321L,
+	0xAE7367CAL, 0x5C18E4C9L, 0x4F48173DL, 0xBD23943EL,
+	0xF36E6F75L, 0x0105EC76L, 0x12551F82L, 0xE03E9C81L,
+	0x34F4F86AL, 0xC69F7B69L, 0xD5CF889DL, 0x27A40B9EL,
+	0x79B737BAL, 0x8BDCB4B9L, 0x988C474DL, 0x6AE7C44EL,
+	0xBE2DA0A5L, 0x4C4623A6L, 0x5F16D052L, 0xAD7D5351L
+};
+
+// NOTE: See source URL at top of this file for multitable implementation which
+//       offers a performance boost at the cost of ~8KB of static tables.
+
+uint32_t
+ComputeCrc32c(uint32_t crc, const void *buf, size_t size)
+{
+	const uint8_t *p = buf;
+
+
+	while (size--)
+		crc = crc32Table[(crc ^ *p++) & 0xff] ^ (crc >> 8);
+
+	return crc;
+}
diff --git a/xpcom/io/crc32c.h b/xpcom/io/crc32c.h
new file mode 100644
index 000000000..f7035fa15
--- /dev/null
+++ b/xpcom/io/crc32c.h
@@ -0,0 +1,23 @@
+#ifndef crc32c_h
+#define crc32c_h
+
+#include <stdint.h>
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// Compute a CRC32c as defined in RFC3720.  This is a different polynomial than
+// what is used in the crc for zlib, etc.  Typical usage to calculate a new CRC:
+//
+//    ComputeCrc32c(~0, buffer, bufferLength);
+//
+uint32_t
+ComputeCrc32c(uint32_t aCrc, const void *aBuf, size_t aSize);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#endif // crc32c_h
diff --git a/xpcom/io/moz.build b/xpcom/io/moz.build
new file mode 100644
index 000000000..6f21e0a72
--- /dev/null
+++ b/xpcom/io/moz.build
@@ -0,0 +1,140 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+XPIDL_SOURCES += [
+    'nsIAsyncInputStream.idl',
+    'nsIAsyncOutputStream.idl',
+    'nsIBinaryInputStream.idl',
+    'nsIBinaryOutputStream.idl',
+    'nsICloneableInputStream.idl',
+    'nsIConverterInputStream.idl',
+    'nsIConverterOutputStream.idl',
+    'nsIDirectoryEnumerator.idl',
+    'nsIDirectoryService.idl',
+    'nsIFile.idl',
+    'nsIInputStream.idl',
+    'nsIInputStreamTee.idl',
+    'nsIIOUtil.idl',
+    'nsILineInputStream.idl',
+    'nsILocalFile.idl',
+    'nsILocalFileWin.idl',
+    'nsIMultiplexInputStream.idl',
+    'nsIObjectInputStream.idl',
+    'nsIObjectOutputStream.idl',
+    'nsIOutputStream.idl',
+    'nsIPipe.idl',
+    'nsISafeOutputStream.idl',
+    'nsIScriptableBase64Encoder.idl',
+    'nsIScriptableInputStream.idl',
+    'nsISeekableStream.idl',
+    'nsIStorageStream.idl',
+    'nsIStreamBufferAccess.idl',
+    'nsIStringStream.idl',
+    'nsIUnicharInputStream.idl',
+    'nsIUnicharLineInputStream.idl',
+    'nsIUnicharOutputStream.idl',
+]
+
+if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa':
+    XPIDL_SOURCES += [
+        'nsILocalFileMac.idl',
+    ]
+
+if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'windows':
+    EXPORTS += ['nsLocalFileWin.h']
+    EXPORTS.mozilla += [
+      'FileUtilsWin.h',
+    ]
+    SOURCES += [
+        'FileUtilsWin.cpp',
+        'nsLocalFileWin.cpp',
+    ]
+else:
+    EXPORTS += ['nsLocalFileUnix.h']
+    SOURCES += [
+        'nsLocalFileUnix.cpp',
+    ]
+
+XPIDL_MODULE = 'xpcom_io'
+
+EXPORTS += [
+    'nsAnonymousTemporaryFile.h',
+    'nsAppDirectoryServiceDefs.h',
+    'nsDirectoryService.h',
+    'nsDirectoryServiceAtomList.h',
+    'nsDirectoryServiceDefs.h',
+    'nsDirectoryServiceUtils.h',
+    'nsEscape.h',
+    'nsLinebreakConverter.h',
+    'nsLocalFile.h',
+    'nsMultiplexInputStream.h',
+    'nsNativeCharsetUtils.h',
+    'nsScriptableInputStream.h',
+    'nsStorageStream.h',
+    'nsStreamUtils.h',
+    'nsStringStream.h',
+    'nsUnicharInputStream.h',
+    'nsWildCard.h',
+    'SlicedInputStream.h',
+    'SpecialSystemDirectory.h',
+]
+
+EXPORTS.mozilla += [
+    'Base64.h',
+    'SnappyCompressOutputStream.h',
+    'SnappyFrameUtils.h',
+    'SnappyUncompressInputStream.h',
+]
+
+UNIFIED_SOURCES += [
+    'Base64.cpp',
+    'crc32c.c',
+    'nsAnonymousTemporaryFile.cpp',
+    'nsAppFileLocationProvider.cpp',
+    'nsBinaryStream.cpp',
+    'nsDirectoryService.cpp',
+    'nsEscape.cpp',
+    'nsInputStreamTee.cpp',
+    'nsIOUtil.cpp',
+    'nsLinebreakConverter.cpp',
+    'nsLocalFileCommon.cpp',
+    'nsMultiplexInputStream.cpp',
+    'nsNativeCharsetUtils.cpp',
+    'nsPipe3.cpp',
+    'nsScriptableBase64Encoder.cpp',
+    'nsScriptableInputStream.cpp',
+    'nsSegmentedBuffer.cpp',
+    'nsStorageStream.cpp',
+    'nsStreamUtils.cpp',
+    'nsStringStream.cpp',
+    'nsUnicharInputStream.cpp',
+    'nsWildCard.cpp',
+    'SlicedInputStream.cpp',
+    'SnappyCompressOutputStream.cpp',
+    'SnappyFrameUtils.cpp',
+    'SnappyUncompressInputStream.cpp',
+    'SpecialSystemDirectory.cpp',
+]
+
+if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa':
+    SOURCES += [
+        'CocoaFileUtils.mm',
+    ]
+
+include('/ipc/chromium/chromium-config.mozbuild')
+
+FINAL_LIBRARY = 'xul'
+
+if CONFIG['OS_ARCH'] == 'Linux' and 'lib64' in CONFIG['libdir']:
+    DEFINES['HAVE_USR_LIB64_DIR'] = True
+
+LOCAL_INCLUDES += ['!..']
+
+if CONFIG['_MSC_VER']:
+    # This is intended as a temporary hack to support building with VS2015.
+    # '_snwprintf' : format string '%s' requires an argument of type 'wchar_t *',
+    # but variadic argument 3 has type 'char16ptr_t'
+    CXXFLAGS += ['-wd4477']
diff --git a/xpcom/io/nsAnonymousTemporaryFile.cpp b/xpcom/io/nsAnonymousTemporaryFile.cpp
new file mode 100644
index 000000000..586e552c4
--- /dev/null
+++ b/xpcom/io/nsAnonymousTemporaryFile.cpp
@@ -0,0 +1,314 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+#include "mozilla/dom/ContentChild.h"
+#include "mozilla/SyncRunnable.h"
+#include "nsAnonymousTemporaryFile.h"
+#include "nsDirectoryServiceUtils.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsXULAppAPI.h"
+#include "nsCOMPtr.h"
+#include "nsString.h"
+#include "nsAppDirectoryServiceDefs.h"
+#include "prio.h"
+#include "private/pprio.h"
+
+#ifdef XP_WIN
+#include "nsIObserver.h"
+#include "nsIObserverService.h"
+#include "mozilla/Services.h"
+#include "nsIIdleService.h"
+#include "nsISimpleEnumerator.h"
+#include "nsIFile.h"
+#include "nsAutoPtr.h"
+#include "nsITimer.h"
+#include "nsCRT.h"
+
+#endif
+
+using namespace mozilla;
+
+// We store the temp files in the system temp dir.
+//
+// On Windows systems in particular we use a sub-directory of the temp
+// directory, because:
+//   1. DELETE_ON_CLOSE is unreliable on Windows, in particular if we power
+//      cycle (and perhaps if we crash) the files are not deleted. We store
+//      the temporary files in a known sub-dir so that we can find and delete
+//      them easily and quickly.
+//   2. On Windows NT the system temp dir is in the user's $HomeDir/AppData,
+//      so we can be sure the user always has write privileges to that directory;
+//      if the sub-dir for our temp files was in some shared location and
+//      was created by a privileged user, it's possible that other users
+//      wouldn't have write access to that sub-dir. (Non-Windows systems
+//      don't store their temp files in a sub-dir, so this isn't an issue on
+//      those platforms).
+//   3. Content processes can access the system temp dir
+//      (NS_GetSpecialDirectory fails on NS_APP_USER_PROFILE_LOCAL_50_DIR
+//      for content process for example, which is where we previously stored
+//      temp files on Windows). This argument applies to all platforms, not
+//      just Windows.
+static nsresult
+GetTempDir(nsIFile** aTempDir)
+{
+  if (NS_WARN_IF(!aTempDir)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  nsCOMPtr<nsIFile> tmpFile;
+  nsresult rv = NS_GetSpecialDirectory(NS_OS_TEMP_DIR, getter_AddRefs(tmpFile));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+#ifdef XP_WIN
+  // On windows DELETE_ON_CLOSE is unreliable, so we store temporary files
+  // in a subdir of the temp dir and delete that in an idle service observer
+  // to ensure it's been cleared.
+  rv = tmpFile->AppendNative(nsDependentCString("mozilla-temp-files"));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+  rv = tmpFile->Create(nsIFile::DIRECTORY_TYPE, 0700);
+  if (rv != NS_ERROR_FILE_ALREADY_EXISTS && NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+#endif
+
+  tmpFile.forget(aTempDir);
+
+  return NS_OK;
+}
+
+namespace {
+
+class nsRemoteAnonymousTemporaryFileRunnable : public Runnable
+{
+public:
+  dom::FileDescOrError *mResultPtr;
+  explicit nsRemoteAnonymousTemporaryFileRunnable(dom::FileDescOrError *aResultPtr)
+  : mResultPtr(aResultPtr)
+  { }
+
+protected:
+  NS_IMETHOD Run() override {
+    dom::ContentChild* child = dom::ContentChild::GetSingleton();
+    MOZ_ASSERT(child);
+    child->SendOpenAnonymousTemporaryFile(mResultPtr);
+    return NS_OK;
+  }
+};
+
+} // namespace
+
+nsresult
+NS_OpenAnonymousTemporaryFile(PRFileDesc** aOutFileDesc)
+{
+  if (NS_WARN_IF(!aOutFileDesc)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  if (dom::ContentChild* child = dom::ContentChild::GetSingleton()) {
+    dom::FileDescOrError fd = NS_OK;
+    if (NS_IsMainThread()) {
+      child->SendOpenAnonymousTemporaryFile(&fd);
+    } else {
+      nsCOMPtr<nsIThread> mainThread = do_GetMainThread();
+      MOZ_ASSERT(mainThread);
+      SyncRunnable::DispatchToThread(mainThread,
+        new nsRemoteAnonymousTemporaryFileRunnable(&fd));
+    }
+    if (fd.type() == dom::FileDescOrError::Tnsresult) {
+      nsresult rv = fd.get_nsresult();
+      MOZ_ASSERT(NS_FAILED(rv));
+      return rv;
+    }
+    auto rawFD = fd.get_FileDescriptor().ClonePlatformHandle();
+    *aOutFileDesc = PR_ImportFile(PROsfd(rawFD.release()));
+    return NS_OK;
+  }
+
+  nsresult rv;
+  nsCOMPtr<nsIFile> tmpFile;
+  rv = GetTempDir(getter_AddRefs(tmpFile));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  // Give the temp file a name with a random element. CreateUnique will also
+  // append a counter to the name if it encounters a name collision. Adding
+  // a random element to the name reduces the likelihood of a name collision,
+  // so that CreateUnique() doesn't end up trying a lot of name variants in
+  // its "try appending an incrementing counter" loop, as file IO can be
+  // expensive on some mobile flash drives.
+  nsAutoCString name("mozilla-temp-");
+  name.AppendInt(rand());
+
+  rv = tmpFile->AppendNative(name);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = tmpFile->CreateUnique(nsIFile::NORMAL_FILE_TYPE, 0700);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = tmpFile->OpenNSPRFileDesc(PR_RDWR | nsIFile::DELETE_ON_CLOSE,
+                                 PR_IRWXU, aOutFileDesc);
+
+  return rv;
+}
+
+#ifdef XP_WIN
+
+// On Windows we have an idle service observer that runs some time after
+// startup and deletes any stray anonymous temporary files...
+
+// Duration of idle time before we'll get a callback whereupon we attempt to
+// remove any stray and unused anonymous temp files.
+#define TEMP_FILE_IDLE_TIME_S 30
+
+// The nsAnonTempFileRemover is created in a timer, which sets an idle observer.
+// This is expiration time (in ms) which initial timer is set for (3 minutes).
+#define SCHEDULE_TIMEOUT_MS 3 * 60 * 1000
+
+#define XPCOM_SHUTDOWN_TOPIC "xpcom-shutdown"
+
+// This class adds itself as an idle observer. When the application has
+// been idle for about 30 seconds we'll get a notification, whereupon we'll
+// attempt to delete ${TempDir}/mozilla-temp-files/. This is to ensure all
+// temp files that were supposed to be deleted on application exit were actually
+// deleted, as they may not be if we previously crashed. See bugs 572579 and
+// 785662. This is only needed on some versions of Windows,
+// nsIFile::DELETE_ON_CLOSE works on other platforms.
+// This class adds itself as a shutdown observer so that it can cancel the
+// idle observer and its timer on shutdown. Note: the observer and idle
+// services hold references to instances of this object, and those references
+// are what keep this object alive.
+class nsAnonTempFileRemover final : public nsIObserver
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  nsAnonTempFileRemover() {}
+
+  nsresult Init()
+  {
+    // We add the idle observer in a timer, so that the app has enough
+    // time to start up before we add the idle observer. If we register the
+    // idle observer too early, it will be registered before the fake idle
+    // service is installed when running in xpcshell, and this interferes with
+    // the fake idle service, causing xpcshell-test failures.
+    mTimer = do_CreateInstance(NS_TIMER_CONTRACTID);
+    if (NS_WARN_IF(!mTimer)) {
+      return NS_ERROR_FAILURE;
+    }
+    nsresult rv = mTimer->Init(this,
+                               SCHEDULE_TIMEOUT_MS,
+                               nsITimer::TYPE_ONE_SHOT);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    // Register shutdown observer so we can cancel the timer if we shutdown before
+    // the timer runs.
+    nsCOMPtr<nsIObserverService> obsSrv = services::GetObserverService();
+    if (NS_WARN_IF(!obsSrv)) {
+      return NS_ERROR_FAILURE;
+    }
+    return obsSrv->AddObserver(this, XPCOM_SHUTDOWN_TOPIC, false);
+  }
+
+  void Cleanup()
+  {
+    // Cancel timer.
+    if (mTimer) {
+      mTimer->Cancel();
+      mTimer = nullptr;
+    }
+    // Remove idle service observer.
+    nsCOMPtr<nsIIdleService> idleSvc =
+      do_GetService("@mozilla.org/widget/idleservice;1");
+    if (idleSvc) {
+      idleSvc->RemoveIdleObserver(this, TEMP_FILE_IDLE_TIME_S);
+    }
+    // Remove shutdown observer.
+    nsCOMPtr<nsIObserverService> obsSrv = services::GetObserverService();
+    if (obsSrv) {
+      obsSrv->RemoveObserver(this, XPCOM_SHUTDOWN_TOPIC);
+    }
+  }
+
+  NS_IMETHODIMP Observe(nsISupports* aSubject,
+                        const char* aTopic,
+                        const char16_t* aData)
+  {
+    if (nsCRT::strcmp(aTopic, NS_TIMER_CALLBACK_TOPIC) == 0 &&
+        NS_FAILED(RegisterIdleObserver())) {
+      Cleanup();
+    } else if (nsCRT::strcmp(aTopic, OBSERVER_TOPIC_IDLE) == 0) {
+      // The user has been idle for a while, clean up the temp files.
+      // The idle service will drop its reference to this object after
+      // we exit, destroying this object.
+      RemoveAnonTempFileFiles();
+      Cleanup();
+    } else if (nsCRT::strcmp(aTopic, XPCOM_SHUTDOWN_TOPIC) == 0) {
+      Cleanup();
+    }
+    return NS_OK;
+  }
+
+  nsresult RegisterIdleObserver()
+  {
+    // Add this as an idle observer. When we've been idle for
+    // TEMP_FILE_IDLE_TIME_S seconds, we'll get a notification, and we'll then
+    // try to delete any stray temp files.
+    nsCOMPtr<nsIIdleService> idleSvc =
+      do_GetService("@mozilla.org/widget/idleservice;1");
+    if (!idleSvc) {
+      return NS_ERROR_FAILURE;
+    }
+    return idleSvc->AddIdleObserver(this, TEMP_FILE_IDLE_TIME_S);
+  }
+
+  void RemoveAnonTempFileFiles()
+  {
+    nsCOMPtr<nsIFile> tmpDir;
+    nsresult rv = GetTempDir(getter_AddRefs(tmpDir));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return;
+    }
+
+    // Remove the directory recursively.
+    tmpDir->Remove(true);
+  }
+
+private:
+  ~nsAnonTempFileRemover() {}
+
+  nsCOMPtr<nsITimer> mTimer;
+};
+
+NS_IMPL_ISUPPORTS(nsAnonTempFileRemover, nsIObserver)
+
+nsresult
+CreateAnonTempFileRemover()
+{
+  // Create a temp file remover. If Init() succeeds, the temp file remover is kept
+  // alive by a reference held by the observer service, since the temp file remover
+  // is a shutdown observer. We only create the temp file remover if we're running
+  // in the main process; there's no point in doing the temp file removal multiple
+  // times per startup.
+  if (!XRE_IsParentProcess()) {
+    return NS_OK;
+  }
+  RefPtr<nsAnonTempFileRemover> tempRemover = new nsAnonTempFileRemover();
+  return tempRemover->Init();
+}
+
+#endif
+
diff --git a/xpcom/io/nsAnonymousTemporaryFile.h b/xpcom/io/nsAnonymousTemporaryFile.h
new file mode 100644
index 000000000..d2f39528f
--- /dev/null
+++ b/xpcom/io/nsAnonymousTemporaryFile.h
@@ -0,0 +1,31 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#pragma once
+
+#include "prio.h"
+#include "nscore.h"
+
+/**
+ * OpenAnonymousTemporaryFile
+ *
+ * Creates and opens a temporary file which has a random name. Callers have no
+ * control over the file name, and the file is opened in a temporary location
+ * which is appropriate for the platform.
+ *
+ * Upon success, aOutFileDesc contains an opened handle to the temporary file.
+ * The caller is responsible for closing the file when they're finished with it.
+ *
+ * The file will be deleted when the file handle is closed. On non-Windows
+ * platforms the file will be unlinked before this function returns. On Windows
+ * the OS supplied delete-on-close mechanism is unreliable if the application
+ * crashes or the computer power cycles unexpectedly, so unopened temporary
+ * files are purged at some time after application startup.
+ *
+ */
+nsresult
+NS_OpenAnonymousTemporaryFile(PRFileDesc** aOutFileDesc);
+
diff --git a/xpcom/io/nsAppDirectoryServiceDefs.h b/xpcom/io/nsAppDirectoryServiceDefs.h
new file mode 100644
index 000000000..aa0a68816
--- /dev/null
+++ b/xpcom/io/nsAppDirectoryServiceDefs.h
@@ -0,0 +1,118 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsAppDirectoryServiceDefs_h___
+#define nsAppDirectoryServiceDefs_h___
+
+//========================================================================================
+//
+// Defines property names for directories available from standard nsIDirectoryServiceProviders.
+// These keys are not guaranteed to exist because the nsIDirectoryServiceProviders which
+// provide them are optional.
+//
+// Keys whose definition ends in "DIR" or "FILE" return a single nsIFile (or subclass).
+// Keys whose definition ends in "LIST" return an nsISimpleEnumerator which enumerates a
+// list of file objects.
+//
+// System and XPCOM level properties are defined in nsDirectoryServiceDefs.h.
+//
+//========================================================================================
+
+
+// --------------------------------------------------------------------------------------
+// Files and directories which exist on a per-product basis
+// --------------------------------------------------------------------------------------
+
+#define NS_APP_APPLICATION_REGISTRY_FILE        "AppRegF"
+#define NS_APP_APPLICATION_REGISTRY_DIR         "AppRegD"
+
+#define NS_APP_DEFAULTS_50_DIR                  "DefRt"         // The root dir of all defaults dirs
+#define NS_APP_PREF_DEFAULTS_50_DIR             "PrfDef"
+                                                                                                                       
+#define NS_APP_USER_PROFILES_ROOT_DIR           "DefProfRt"     // The dir where user profile dirs live.
+#define NS_APP_USER_PROFILES_LOCAL_ROOT_DIR     "DefProfLRt"  // The dir where user profile temp dirs live.
+
+#define NS_APP_RES_DIR                          "ARes"
+#define NS_APP_CHROME_DIR                       "AChrom"
+#define NS_APP_PLUGINS_DIR                      "APlugns"       // Deprecated - use NS_APP_PLUGINS_DIR_LIST
+#define NS_APP_SEARCH_DIR                       "SrchPlugns"
+
+#define NS_APP_CHROME_DIR_LIST                  "AChromDL"
+#define NS_APP_PLUGINS_DIR_LIST                 "APluginsDL"
+#define NS_APP_SEARCH_DIR_LIST                  "SrchPluginsDL"
+#define NS_APP_DISTRIBUTION_SEARCH_DIR_LIST     "SrchPluginsDistDL"
+
+// --------------------------------------------------------------------------------------
+// Files and directories which exist on a per-profile basis
+// These locations are typically provided by the profile mgr
+// --------------------------------------------------------------------------------------
+
+// In a shared profile environment, prefixing a profile-relative
+// key with NS_SHARED returns a location that is shared by
+// other users of the profile. Without this prefix, the consumer
+// has exclusive access to this location.
+
+#define NS_SHARED                               "SHARED"
+
+#define NS_APP_PREFS_50_DIR                     "PrefD"         // Directory which contains user prefs       
+#define NS_APP_PREFS_50_FILE                    "PrefF"
+#define NS_APP_PREFS_DEFAULTS_DIR_LIST          "PrefDL"
+#define NS_EXT_PREFS_DEFAULTS_DIR_LIST          "ExtPrefDL"
+#define NS_APP_PREFS_OVERRIDE_DIR               "PrefDOverride" // Directory for per-profile defaults
+
+#define NS_APP_USER_PROFILE_50_DIR              "ProfD"
+#define NS_APP_USER_PROFILE_LOCAL_50_DIR        "ProfLD"
+
+#define NS_APP_USER_CHROME_DIR                  "UChrm"
+#define NS_APP_USER_SEARCH_DIR                  "UsrSrchPlugns"
+
+#define NS_APP_LOCALSTORE_50_FILE               "LclSt"
+#define NS_APP_USER_PANELS_50_FILE              "UPnls"
+#define NS_APP_USER_MIMETYPES_50_FILE           "UMimTyp"
+#define NS_APP_CACHE_PARENT_DIR                 "cachePDir"
+
+#define NS_APP_DOWNLOADS_50_FILE                "DLoads"
+
+#define NS_APP_SEARCH_50_FILE                   "SrchF"
+
+#define NS_APP_INSTALL_CLEANUP_DIR              "XPIClnupD"  //location of xpicleanup.dat xpicleanup.exe 
+
+#define NS_APP_INDEXEDDB_PARENT_DIR             "indexedDBPDir"
+
+#define NS_APP_PERMISSION_PARENT_DIR            "permissionDBPDir"
+
+#if (defined(XP_WIN) || defined(XP_MACOSX)) && defined(MOZ_CONTENT_SANDBOX)
+//
+// NS_APP_CONTENT_PROCESS_TEMP_DIR refers to a directory that is read and
+// write accessible from a sandboxed content process. The key may be used in
+// either process, but the directory is intended to be used for short-lived
+// files that need to be saved to the filesystem by the content process and
+// don't need to survive browser restarts. The directory is reset on startup.
+// The key is only valid when MOZ_CONTENT_SANDBOX is defined. When
+// MOZ_CONTENT_SANDBOX is defined, the directory the key refers to differs
+// depending on whether or not content sandboxing is enabled.
+//
+// When MOZ_CONTENT_SANDBOX is defined and sandboxing is enabled (versus
+// manually disabled via prefs), the content process replaces NS_OS_TEMP_DIR
+// with NS_APP_CONTENT_PROCESS_TEMP_DIR so that legacy code in content
+// attempting to write to NS_OS_TEMP_DIR will write to
+// NS_APP_CONTENT_PROCESS_TEMP_DIR instead. When MOZ_CONTENT_SANDBOX is
+// defined but sandboxing is disabled, NS_APP_CONTENT_PROCESS_TEMP_DIR
+// falls back to NS_OS_TEMP_DIR in both content and chrome processes.
+//
+// New code should avoid writing to the filesystem from the content process
+// and should instead proxy through the parent process whenever possible.
+//
+// At present, all sandboxed content processes use the same directory for
+// NS_APP_CONTENT_PROCESS_TEMP_DIR, but that should not be relied upon.
+//
+#define NS_APP_CONTENT_PROCESS_TEMP_DIR         "ContentTmpD"
+#else
+// Otherwise NS_APP_CONTENT_PROCESS_TEMP_DIR must match NS_OS_TEMP_DIR.
+#define NS_APP_CONTENT_PROCESS_TEMP_DIR         "TmpD"
+#endif // (defined(XP_WIN) || defined(XP_MACOSX)) && defined(MOZ_CONTENT_SANDBOX)
+
+#endif // nsAppDirectoryServiceDefs_h___
diff --git a/xpcom/io/nsAppFileLocationProvider.cpp b/xpcom/io/nsAppFileLocationProvider.cpp
new file mode 100644
index 000000000..27ccd56dc
--- /dev/null
+++ b/xpcom/io/nsAppFileLocationProvider.cpp
@@ -0,0 +1,609 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsAppFileLocationProvider.h"
+#include "nsAppDirectoryServiceDefs.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsEnumeratorUtils.h"
+#include "nsIAtom.h"
+#include "nsIFile.h"
+#include "nsString.h"
+#include "nsXPIDLString.h"
+#include "nsISimpleEnumerator.h"
+#include "prenv.h"
+#include "nsCRT.h"
+
+#if defined(MOZ_WIDGET_COCOA)
+#include <Carbon/Carbon.h>
+#include "nsILocalFileMac.h"
+#elif defined(XP_WIN)
+#include <windows.h>
+#include <shlobj.h>
+#elif defined(XP_UNIX)
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/param.h>
+#endif
+
+
+// WARNING: These hard coded names need to go away. They need to
+// come from localizable resources
+
+#if defined(MOZ_WIDGET_COCOA)
+#define APP_REGISTRY_NAME NS_LITERAL_CSTRING("Application Registry")
+#define ESSENTIAL_FILES   NS_LITERAL_CSTRING("Essential Files")
+#elif defined(XP_WIN)
+#define APP_REGISTRY_NAME NS_LITERAL_CSTRING("registry.dat")
+#else
+#define APP_REGISTRY_NAME NS_LITERAL_CSTRING("appreg")
+#endif
+
+// define default product directory
+#define DEFAULT_PRODUCT_DIR NS_LITERAL_CSTRING(MOZ_USER_DIR)
+
+// Locally defined keys used by nsAppDirectoryEnumerator
+#define NS_ENV_PLUGINS_DIR          "EnvPlugins"    // env var MOZ_PLUGIN_PATH
+#define NS_USER_PLUGINS_DIR         "UserPlugins"
+
+#ifdef MOZ_WIDGET_COCOA
+#define NS_MACOSX_USER_PLUGIN_DIR   "OSXUserPlugins"
+#define NS_MACOSX_LOCAL_PLUGIN_DIR  "OSXLocalPlugins"
+#define NS_MACOSX_JAVA2_PLUGIN_DIR  "OSXJavaPlugins"
+#elif XP_UNIX
+#define NS_SYSTEM_PLUGINS_DIR       "SysPlugins"
+#endif
+
+#define DEFAULTS_DIR_NAME           NS_LITERAL_CSTRING("defaults")
+#define DEFAULTS_PREF_DIR_NAME      NS_LITERAL_CSTRING("pref")
+#define RES_DIR_NAME                NS_LITERAL_CSTRING("res")
+#define CHROME_DIR_NAME             NS_LITERAL_CSTRING("chrome")
+#define PLUGINS_DIR_NAME            NS_LITERAL_CSTRING("plugins")
+#define SEARCH_DIR_NAME             NS_LITERAL_CSTRING("searchplugins")
+
+//*****************************************************************************
+// nsAppFileLocationProvider::Constructor/Destructor
+//*****************************************************************************
+
+nsAppFileLocationProvider::nsAppFileLocationProvider()
+{
+}
+
+//*****************************************************************************
+// nsAppFileLocationProvider::nsISupports
+//*****************************************************************************
+
+NS_IMPL_ISUPPORTS(nsAppFileLocationProvider,
+                  nsIDirectoryServiceProvider,
+                  nsIDirectoryServiceProvider2)
+
+//*****************************************************************************
+// nsAppFileLocationProvider::nsIDirectoryServiceProvider
+//*****************************************************************************
+
+NS_IMETHODIMP
+nsAppFileLocationProvider::GetFile(const char* aProp, bool* aPersistent,
+                                   nsIFile** aResult)
+{
+  if (NS_WARN_IF(!aProp)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsCOMPtr<nsIFile>  localFile;
+  nsresult rv = NS_ERROR_FAILURE;
+
+  *aResult = nullptr;
+  *aPersistent = true;
+
+#ifdef MOZ_WIDGET_COCOA
+  FSRef fileRef;
+  nsCOMPtr<nsILocalFileMac> macFile;
+#endif
+
+  if (nsCRT::strcmp(aProp, NS_APP_APPLICATION_REGISTRY_DIR) == 0) {
+    rv = GetProductDirectory(getter_AddRefs(localFile));
+  } else if (nsCRT::strcmp(aProp, NS_APP_APPLICATION_REGISTRY_FILE) == 0) {
+    rv = GetProductDirectory(getter_AddRefs(localFile));
+    if (NS_SUCCEEDED(rv)) {
+      rv = localFile->AppendNative(APP_REGISTRY_NAME);
+    }
+  } else if (nsCRT::strcmp(aProp, NS_APP_DEFAULTS_50_DIR) == 0) {
+    rv = CloneMozBinDirectory(getter_AddRefs(localFile));
+    if (NS_SUCCEEDED(rv)) {
+      rv = localFile->AppendRelativeNativePath(DEFAULTS_DIR_NAME);
+    }
+  } else if (nsCRT::strcmp(aProp, NS_APP_PREF_DEFAULTS_50_DIR) == 0) {
+    rv = CloneMozBinDirectory(getter_AddRefs(localFile));
+    if (NS_SUCCEEDED(rv)) {
+      rv = localFile->AppendRelativeNativePath(DEFAULTS_DIR_NAME);
+      if (NS_SUCCEEDED(rv)) {
+        rv = localFile->AppendRelativeNativePath(DEFAULTS_PREF_DIR_NAME);
+      }
+    }
+  } else if (nsCRT::strcmp(aProp, NS_APP_USER_PROFILES_ROOT_DIR) == 0) {
+    rv = GetDefaultUserProfileRoot(getter_AddRefs(localFile));
+  } else if (nsCRT::strcmp(aProp, NS_APP_USER_PROFILES_LOCAL_ROOT_DIR) == 0) {
+    rv = GetDefaultUserProfileRoot(getter_AddRefs(localFile), true);
+  } else if (nsCRT::strcmp(aProp, NS_APP_RES_DIR) == 0) {
+    rv = CloneMozBinDirectory(getter_AddRefs(localFile));
+    if (NS_SUCCEEDED(rv)) {
+      rv = localFile->AppendRelativeNativePath(RES_DIR_NAME);
+    }
+  } else if (nsCRT::strcmp(aProp, NS_APP_CHROME_DIR) == 0) {
+    rv = CloneMozBinDirectory(getter_AddRefs(localFile));
+    if (NS_SUCCEEDED(rv)) {
+      rv = localFile->AppendRelativeNativePath(CHROME_DIR_NAME);
+    }
+  } else if (nsCRT::strcmp(aProp, NS_APP_PLUGINS_DIR) == 0) {
+    rv = CloneMozBinDirectory(getter_AddRefs(localFile));
+    if (NS_SUCCEEDED(rv)) {
+      rv = localFile->AppendRelativeNativePath(PLUGINS_DIR_NAME);
+    }
+  }
+#ifdef MOZ_WIDGET_COCOA
+  else if (nsCRT::strcmp(aProp, NS_MACOSX_USER_PLUGIN_DIR) == 0) {
+    if (::FSFindFolder(kUserDomain, kInternetPlugInFolderType, false,
+                       &fileRef) == noErr) {
+      rv = NS_NewLocalFileWithFSRef(&fileRef, true, getter_AddRefs(macFile));
+      if (NS_SUCCEEDED(rv)) {
+        localFile = macFile;
+      }
+    }
+  } else if (nsCRT::strcmp(aProp, NS_MACOSX_LOCAL_PLUGIN_DIR) == 0) {
+    if (::FSFindFolder(kLocalDomain, kInternetPlugInFolderType, false,
+                       &fileRef) == noErr) {
+      rv = NS_NewLocalFileWithFSRef(&fileRef, true, getter_AddRefs(macFile));
+      if (NS_SUCCEEDED(rv)) {
+        localFile = macFile;
+      }
+    }
+  } else if (nsCRT::strcmp(aProp, NS_MACOSX_JAVA2_PLUGIN_DIR) == 0) {
+    static const char* const java2PluginDirPath =
+      "/System/Library/Java/Support/Deploy.bundle/Contents/Resources/";
+    rv = NS_NewNativeLocalFile(nsDependentCString(java2PluginDirPath), true,
+                               getter_AddRefs(localFile));
+  }
+#else
+  else if (nsCRT::strcmp(aProp, NS_ENV_PLUGINS_DIR) == 0) {
+    NS_ERROR("Don't use nsAppFileLocationProvider::GetFile(NS_ENV_PLUGINS_DIR, ...). "
+             "Use nsAppFileLocationProvider::GetFiles(...).");
+    const char* pathVar = PR_GetEnv("MOZ_PLUGIN_PATH");
+    if (pathVar && *pathVar)
+      rv = NS_NewNativeLocalFile(nsDependentCString(pathVar), true,
+                                 getter_AddRefs(localFile));
+  } else if (nsCRT::strcmp(aProp, NS_USER_PLUGINS_DIR) == 0) {
+#ifdef ENABLE_SYSTEM_EXTENSION_DIRS
+    rv = GetProductDirectory(getter_AddRefs(localFile));
+    if (NS_SUCCEEDED(rv)) {
+      rv = localFile->AppendRelativeNativePath(PLUGINS_DIR_NAME);
+    }
+#else
+    rv = NS_ERROR_FAILURE;
+#endif
+  }
+#ifdef XP_UNIX
+  else if (nsCRT::strcmp(aProp, NS_SYSTEM_PLUGINS_DIR) == 0) {
+#ifdef ENABLE_SYSTEM_EXTENSION_DIRS
+    static const char* const sysLPlgDir =
+#if defined(HAVE_USR_LIB64_DIR) && defined(__LP64__)
+      "/usr/lib64/mozilla/plugins";
+#elif defined(__OpenBSD__) || defined (__FreeBSD__)
+      "/usr/local/lib/mozilla/plugins";
+#else
+      "/usr/lib/mozilla/plugins";
+#endif
+    rv = NS_NewNativeLocalFile(nsDependentCString(sysLPlgDir),
+                               false, getter_AddRefs(localFile));
+#else
+    rv = NS_ERROR_FAILURE;
+#endif
+  }
+#endif
+#endif
+  else if (nsCRT::strcmp(aProp, NS_APP_SEARCH_DIR) == 0) {
+    rv = CloneMozBinDirectory(getter_AddRefs(localFile));
+    if (NS_SUCCEEDED(rv)) {
+      rv = localFile->AppendRelativeNativePath(SEARCH_DIR_NAME);
+    }
+  } else if (nsCRT::strcmp(aProp, NS_APP_USER_SEARCH_DIR) == 0) {
+    rv = NS_GetSpecialDirectory(NS_APP_USER_PROFILE_50_DIR, aResult);
+    if (NS_SUCCEEDED(rv)) {
+      rv = (*aResult)->AppendNative(SEARCH_DIR_NAME);
+    }
+  } else if (nsCRT::strcmp(aProp, NS_APP_INSTALL_CLEANUP_DIR) == 0) {
+    // This is cloned so that embeddors will have a hook to override
+    // with their own cleanup dir.  See bugzilla bug #105087
+    rv = CloneMozBinDirectory(getter_AddRefs(localFile));
+  }
+
+  if (localFile && NS_SUCCEEDED(rv)) {
+    localFile.forget(aResult);
+    return NS_OK;
+  }
+
+  return rv;
+}
+
+
+nsresult
+nsAppFileLocationProvider::CloneMozBinDirectory(nsIFile** aLocalFile)
+{
+  if (NS_WARN_IF(!aLocalFile)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  nsresult rv;
+
+  if (!mMozBinDirectory) {
+    // Get the mozilla bin directory
+    // 1. Check the directory service first for NS_XPCOM_CURRENT_PROCESS_DIR
+    //    This will be set if a directory was passed to NS_InitXPCOM
+    // 2. If that doesn't work, set it to be the current process directory
+    nsCOMPtr<nsIProperties>
+    directoryService(do_GetService(NS_DIRECTORY_SERVICE_CONTRACTID, &rv));
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    rv = directoryService->Get(NS_XPCOM_CURRENT_PROCESS_DIR, NS_GET_IID(nsIFile),
+                               getter_AddRefs(mMozBinDirectory));
+    if (NS_FAILED(rv)) {
+      rv = directoryService->Get(NS_OS_CURRENT_PROCESS_DIR, NS_GET_IID(nsIFile),
+                                 getter_AddRefs(mMozBinDirectory));
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+    }
+  }
+
+  nsCOMPtr<nsIFile> aFile;
+  rv = mMozBinDirectory->Clone(getter_AddRefs(aFile));
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  NS_IF_ADDREF(*aLocalFile = aFile);
+  return NS_OK;
+}
+
+
+//----------------------------------------------------------------------------------------
+// GetProductDirectory - Gets the directory which contains the application data folder
+//
+// UNIX   : ~/.mozilla/
+// WIN    : <Application Data folder on user's machine>\Mozilla
+// Mac    : :Documents:Mozilla:
+//----------------------------------------------------------------------------------------
+nsresult
+nsAppFileLocationProvider::GetProductDirectory(nsIFile** aLocalFile,
+                                               bool aLocal)
+{
+  if (NS_WARN_IF(!aLocalFile)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsresult rv;
+  bool exists;
+  nsCOMPtr<nsIFile> localDir;
+
+#if defined(MOZ_WIDGET_COCOA)
+  FSRef fsRef;
+  OSType folderType = aLocal ? (OSType)kCachedDataFolderType :
+                               (OSType)kDomainLibraryFolderType;
+  OSErr err = ::FSFindFolder(kUserDomain, folderType, kCreateFolder, &fsRef);
+  if (err) {
+    return NS_ERROR_FAILURE;
+  }
+  NS_NewLocalFile(EmptyString(), true, getter_AddRefs(localDir));
+  if (!localDir) {
+    return NS_ERROR_FAILURE;
+  }
+  nsCOMPtr<nsILocalFileMac> localDirMac(do_QueryInterface(localDir));
+  rv = localDirMac->InitWithFSRef(&fsRef);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+#elif defined(XP_WIN)
+  nsCOMPtr<nsIProperties> directoryService =
+    do_GetService(NS_DIRECTORY_SERVICE_CONTRACTID, &rv);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  const char* prop = aLocal ? NS_WIN_LOCAL_APPDATA_DIR : NS_WIN_APPDATA_DIR;
+  rv = directoryService->Get(prop, NS_GET_IID(nsIFile), getter_AddRefs(localDir));
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+#elif defined(XP_UNIX)
+  rv = NS_NewNativeLocalFile(nsDependentCString(PR_GetEnv("HOME")), true,
+                             getter_AddRefs(localDir));
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+#else
+#error dont_know_how_to_get_product_dir_on_your_platform
+#endif
+
+  rv = localDir->AppendRelativeNativePath(DEFAULT_PRODUCT_DIR);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  rv = localDir->Exists(&exists);
+
+  if (NS_SUCCEEDED(rv) && !exists) {
+    rv = localDir->Create(nsIFile::DIRECTORY_TYPE, 0700);
+  }
+
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  localDir.forget(aLocalFile);
+
+  return rv;
+}
+
+
+//----------------------------------------------------------------------------------------
+// GetDefaultUserProfileRoot - Gets the directory which contains each user profile dir
+//
+// UNIX   : ~/.mozilla/
+// WIN    : <Application Data folder on user's machine>\Mozilla\Profiles
+// Mac    : :Documents:Mozilla:Profiles:
+//----------------------------------------------------------------------------------------
+nsresult
+nsAppFileLocationProvider::GetDefaultUserProfileRoot(nsIFile** aLocalFile,
+                                                     bool aLocal)
+{
+  if (NS_WARN_IF(!aLocalFile)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsresult rv;
+  nsCOMPtr<nsIFile> localDir;
+
+  rv = GetProductDirectory(getter_AddRefs(localDir), aLocal);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+#if defined(MOZ_WIDGET_COCOA) || defined(XP_WIN)
+  // These 3 platforms share this part of the path - do them as one
+  rv = localDir->AppendRelativeNativePath(NS_LITERAL_CSTRING("Profiles"));
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  bool exists;
+  rv = localDir->Exists(&exists);
+  if (NS_SUCCEEDED(rv) && !exists) {
+    rv = localDir->Create(nsIFile::DIRECTORY_TYPE, 0775);
+  }
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+#endif
+
+  localDir.forget(aLocalFile);
+
+  return rv;
+}
+
+//*****************************************************************************
+// nsAppFileLocationProvider::nsIDirectoryServiceProvider2
+//*****************************************************************************
+
+class nsAppDirectoryEnumerator : public nsISimpleEnumerator
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  /**
+   * aKeyList is a null-terminated list of properties which are provided by aProvider
+   * They do not need to be publicly defined keys.
+   */
+  nsAppDirectoryEnumerator(nsIDirectoryServiceProvider* aProvider,
+                           const char* aKeyList[]) :
+    mProvider(aProvider),
+    mCurrentKey(aKeyList)
+  {
+  }
+
+  NS_IMETHOD HasMoreElements(bool* aResult) override
+  {
+    while (!mNext && *mCurrentKey) {
+      bool dontCare;
+      nsCOMPtr<nsIFile> testFile;
+      (void)mProvider->GetFile(*mCurrentKey++, &dontCare, getter_AddRefs(testFile));
+      // Don't return a file which does not exist.
+      bool exists;
+      if (testFile && NS_SUCCEEDED(testFile->Exists(&exists)) && exists) {
+        mNext = testFile;
+      }
+    }
+    *aResult = mNext != nullptr;
+    return NS_OK;
+  }
+
+  NS_IMETHOD GetNext(nsISupports** aResult) override
+  {
+    if (NS_WARN_IF(!aResult)) {
+      return NS_ERROR_INVALID_ARG;
+    }
+    *aResult = nullptr;
+
+    bool hasMore;
+    HasMoreElements(&hasMore);
+    if (!hasMore) {
+      return NS_ERROR_FAILURE;
+    }
+
+    *aResult = mNext;
+    NS_IF_ADDREF(*aResult);
+    mNext = nullptr;
+
+    return *aResult ? NS_OK : NS_ERROR_FAILURE;
+  }
+
+protected:
+  nsCOMPtr<nsIDirectoryServiceProvider> mProvider;
+  const char** mCurrentKey;
+  nsCOMPtr<nsIFile> mNext;
+
+  // Virtual destructor since subclass nsPathsDirectoryEnumerator
+  // does not re-implement Release()
+  virtual ~nsAppDirectoryEnumerator()
+  {
+  }
+};
+
+NS_IMPL_ISUPPORTS(nsAppDirectoryEnumerator, nsISimpleEnumerator)
+
+/* nsPathsDirectoryEnumerator and PATH_SEPARATOR
+ * are not used on MacOS/X. */
+
+#if defined(XP_WIN) /* Win32 */
+#define PATH_SEPARATOR ';'
+#else
+#define PATH_SEPARATOR ':'
+#endif
+
+class nsPathsDirectoryEnumerator final
+  : public nsAppDirectoryEnumerator
+{
+  ~nsPathsDirectoryEnumerator() {}
+
+public:
+  /**
+   * aKeyList is a null-terminated list.
+   * The first element is a path list.
+   * The remainder are properties provided by aProvider.
+   * They do not need to be publicly defined keys.
+   */
+  nsPathsDirectoryEnumerator(nsIDirectoryServiceProvider* aProvider,
+                             const char* aKeyList[]) :
+    nsAppDirectoryEnumerator(aProvider, aKeyList + 1),
+    mEndPath(aKeyList[0])
+  {
+  }
+
+  NS_IMETHOD HasMoreElements(bool* aResult)
+  {
+    if (mEndPath)
+      while (!mNext && *mEndPath) {
+        const char* pathVar = mEndPath;
+
+        // skip PATH_SEPARATORs at the begining of the mEndPath
+        while (*pathVar == PATH_SEPARATOR) {
+          ++pathVar;
+        }
+
+        do {
+          ++mEndPath;
+        } while (*mEndPath && *mEndPath != PATH_SEPARATOR);
+
+        nsCOMPtr<nsIFile> localFile;
+        NS_NewNativeLocalFile(Substring(pathVar, mEndPath),
+                              true,
+                              getter_AddRefs(localFile));
+        if (*mEndPath == PATH_SEPARATOR) {
+          ++mEndPath;
+        }
+        // Don't return a "file" (directory) which does not exist.
+        bool exists;
+        if (localFile &&
+            NS_SUCCEEDED(localFile->Exists(&exists)) &&
+            exists) {
+          mNext = localFile;
+        }
+      }
+    if (mNext) {
+      *aResult = true;
+    } else {
+      nsAppDirectoryEnumerator::HasMoreElements(aResult);
+    }
+
+    return NS_OK;
+  }
+
+protected:
+  const char* mEndPath;
+};
+
+NS_IMETHODIMP
+nsAppFileLocationProvider::GetFiles(const char* aProp,
+                                    nsISimpleEnumerator** aResult)
+{
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  *aResult = nullptr;
+  nsresult rv = NS_ERROR_FAILURE;
+
+  if (!nsCRT::strcmp(aProp, NS_APP_PLUGINS_DIR_LIST)) {
+#ifdef MOZ_WIDGET_COCOA
+    // As of Java for Mac OS X 10.5 Update 10, Apple has (in effect) deprecated Java Plugin2 on
+    // on OS X 10.5, and removed the soft link to it from /Library/Internet Plug-Ins/.  Java
+    // Plugin2 is still present and usable, but there are no longer any links to it in the
+    // "normal" locations.  So we won't be able to find it unless we look in the "non-normal"
+    // location where it actually is.  Safari can use the WebKit-specific JavaPluginCocoa.bundle,
+    // which (of course) is still fully supported on OS X 10.5.  But we have no alternative to
+    // using Java Plugin2.  For more information see bug 668639.
+    static const char* keys[] = {
+      NS_APP_PLUGINS_DIR,
+      NS_MACOSX_USER_PLUGIN_DIR,
+      NS_MACOSX_LOCAL_PLUGIN_DIR,
+      IsOSXLeopard() ? NS_MACOSX_JAVA2_PLUGIN_DIR : nullptr,
+      nullptr
+    };
+    *aResult = new nsAppDirectoryEnumerator(this, keys);
+#else
+#ifdef XP_UNIX
+    static const char* keys[] = { nullptr, NS_USER_PLUGINS_DIR, NS_APP_PLUGINS_DIR, NS_SYSTEM_PLUGINS_DIR, nullptr };
+#else
+    static const char* keys[] = { nullptr, NS_USER_PLUGINS_DIR, NS_APP_PLUGINS_DIR, nullptr };
+#endif
+    if (!keys[0] && !(keys[0] = PR_GetEnv("MOZ_PLUGIN_PATH"))) {
+      static const char nullstr = 0;
+      keys[0] = &nullstr;
+    }
+    *aResult = new nsPathsDirectoryEnumerator(this, keys);
+#endif
+    NS_ADDREF(*aResult);
+    rv = NS_OK;
+  }
+  if (!nsCRT::strcmp(aProp, NS_APP_SEARCH_DIR_LIST)) {
+    static const char* keys[] = { nullptr, NS_APP_USER_SEARCH_DIR, nullptr };
+    if (!keys[0] && !(keys[0] = PR_GetEnv("MOZ_SEARCH_ENGINE_PATH"))) {
+      static const char nullstr = 0;
+      keys[0] = &nullstr;
+    }
+    *aResult = new nsPathsDirectoryEnumerator(this, keys);
+    NS_ADDREF(*aResult);
+    rv = NS_OK;
+  }
+  if (!strcmp(aProp, NS_APP_DISTRIBUTION_SEARCH_DIR_LIST)) {
+    return NS_NewEmptyEnumerator(aResult);
+  }
+  return rv;
+}
+
+#if defined(MOZ_WIDGET_COCOA)
+bool
+nsAppFileLocationProvider::IsOSXLeopard()
+{
+  static SInt32 version = 0;
+
+  if (!version) {
+    OSErr err = ::Gestalt(gestaltSystemVersion, &version);
+    if (err != noErr) {
+      version = 0;
+    } else {
+      version &= 0xFFFF; // The system version is in the low order word
+    }
+  }
+
+  return ((version >= 0x1050) && (version < 0x1060));
+}
+#endif
diff --git a/xpcom/io/nsAppFileLocationProvider.h b/xpcom/io/nsAppFileLocationProvider.h
new file mode 100644
index 000000000..248c5b828
--- /dev/null
+++ b/xpcom/io/nsAppFileLocationProvider.h
@@ -0,0 +1,55 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsAppFileLocationProvider_h
+#define nsAppFileLocationProvider_h
+
+#include "nsIDirectoryService.h"
+#include "nsIFile.h"
+#include "mozilla/Attributes.h"
+
+class nsIFile;
+
+//*****************************************************************************
+// class nsAppFileLocationProvider
+//*****************************************************************************
+
+class nsAppFileLocationProvider final : public nsIDirectoryServiceProvider2
+{
+public:
+  nsAppFileLocationProvider();
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIDIRECTORYSERVICEPROVIDER
+  NS_DECL_NSIDIRECTORYSERVICEPROVIDER2
+
+private:
+  ~nsAppFileLocationProvider()
+  {
+  }
+
+protected:
+  nsresult CloneMozBinDirectory(nsIFile** aLocalFile);
+  /**
+  * Get the product directory. This is a user-specific directory for storing
+  * application settings (e.g. the Application Data directory on windows
+  * systems).
+  * @param aLocal If true, should try to get a directory that is only stored
+  *               locally (ie not transferred with roaming profiles)
+  */
+  nsresult GetProductDirectory(nsIFile** aLocalFile,
+                               bool aLocal = false);
+  nsresult GetDefaultUserProfileRoot(nsIFile** aLocalFile,
+                                     bool aLocal = false);
+
+#if defined(MOZ_WIDGET_COCOA)
+  static bool IsOSXLeopard();
+#endif
+
+  nsCOMPtr<nsIFile> mMozBinDirectory;
+};
+
+#endif
diff --git a/xpcom/io/nsBinaryStream.cpp b/xpcom/io/nsBinaryStream.cpp
new file mode 100644
index 000000000..82159952e
--- /dev/null
+++ b/xpcom/io/nsBinaryStream.cpp
@@ -0,0 +1,1016 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * This file contains implementations of the nsIBinaryInputStream and
+ * nsIBinaryOutputStream interfaces.  Together, these interfaces allows reading
+ * and writing of primitive data types (integers, floating-point values,
+ * booleans, etc.) to a stream in a binary, untagged, fixed-endianness format.
+ * This might be used, for example, to implement network protocols or to
+ * produce architecture-neutral binary disk files, i.e. ones that can be read
+ * and written by both big-endian and little-endian platforms.  Output is
+ * written in big-endian order (high-order byte first), as this is traditional
+ * network order.
+ *
+ * @See nsIBinaryInputStream
+ * @See nsIBinaryOutputStream
+ */
+#include <algorithm>
+#include <string.h>
+
+#include "nsBinaryStream.h"
+
+#include "mozilla/EndianUtils.h"
+#include "mozilla/PodOperations.h"
+#include "mozilla/UniquePtr.h"
+
+#include "nsCRT.h"
+#include "nsString.h"
+#include "nsISerializable.h"
+#include "nsIClassInfo.h"
+#include "nsComponentManagerUtils.h"
+#include "nsIURI.h" // for NS_IURI_IID
+#include "nsIX509Cert.h" // for NS_IX509CERT_IID
+
+#include "jsfriendapi.h"
+
+using mozilla::MakeUnique;
+using mozilla::PodCopy;
+using mozilla::UniquePtr;
+
+NS_IMPL_ISUPPORTS(nsBinaryOutputStream,
+                  nsIObjectOutputStream,
+                  nsIBinaryOutputStream,
+                  nsIOutputStream)
+
+NS_IMETHODIMP
+nsBinaryOutputStream::Flush()
+{
+  if (NS_WARN_IF(!mOutputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mOutputStream->Flush();
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::Close()
+{
+  if (NS_WARN_IF(!mOutputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mOutputStream->Close();
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::Write(const char* aBuf, uint32_t aCount,
+                            uint32_t* aActualBytes)
+{
+  if (NS_WARN_IF(!mOutputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mOutputStream->Write(aBuf, aCount, aActualBytes);
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteFrom(nsIInputStream* aInStr, uint32_t aCount,
+                                uint32_t* aResult)
+{
+  NS_NOTREACHED("WriteFrom");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteSegments(nsReadSegmentFun aReader, void* aClosure,
+                                    uint32_t aCount, uint32_t* aResult)
+{
+  NS_NOTREACHED("WriteSegments");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::IsNonBlocking(bool* aNonBlocking)
+{
+  if (NS_WARN_IF(!mOutputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mOutputStream->IsNonBlocking(aNonBlocking);
+}
+
+nsresult
+nsBinaryOutputStream::WriteFully(const char* aBuf, uint32_t aCount)
+{
+  if (NS_WARN_IF(!mOutputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  nsresult rv;
+  uint32_t bytesWritten;
+
+  rv = mOutputStream->Write(aBuf, aCount, &bytesWritten);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (bytesWritten != aCount) {
+    return NS_ERROR_FAILURE;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::SetOutputStream(nsIOutputStream* aOutputStream)
+{
+  if (NS_WARN_IF(!aOutputStream)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  mOutputStream = aOutputStream;
+  mBufferAccess = do_QueryInterface(aOutputStream);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteBoolean(bool aBoolean)
+{
+  return Write8(aBoolean);
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::Write8(uint8_t aByte)
+{
+  return WriteFully((const char*)&aByte, sizeof(aByte));
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::Write16(uint16_t aNum)
+{
+  aNum = mozilla::NativeEndian::swapToBigEndian(aNum);
+  return WriteFully((const char*)&aNum, sizeof(aNum));
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::Write32(uint32_t aNum)
+{
+  aNum = mozilla::NativeEndian::swapToBigEndian(aNum);
+  return WriteFully((const char*)&aNum, sizeof(aNum));
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::Write64(uint64_t aNum)
+{
+  nsresult rv;
+  uint32_t bytesWritten;
+
+  aNum = mozilla::NativeEndian::swapToBigEndian(aNum);
+  rv = Write(reinterpret_cast<char*>(&aNum), sizeof(aNum), &bytesWritten);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (bytesWritten != sizeof(aNum)) {
+    return NS_ERROR_FAILURE;
+  }
+  return rv;
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteFloat(float aFloat)
+{
+  NS_ASSERTION(sizeof(float) == sizeof(uint32_t),
+               "False assumption about sizeof(float)");
+  return Write32(*reinterpret_cast<uint32_t*>(&aFloat));
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteDouble(double aDouble)
+{
+  NS_ASSERTION(sizeof(double) == sizeof(uint64_t),
+               "False assumption about sizeof(double)");
+  return Write64(*reinterpret_cast<uint64_t*>(&aDouble));
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteStringZ(const char* aString)
+{
+  uint32_t length;
+  nsresult rv;
+
+  length = strlen(aString);
+  rv = Write32(length);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  return WriteFully(aString, length);
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteWStringZ(const char16_t* aString)
+{
+  uint32_t length, byteCount;
+  nsresult rv;
+
+  length = NS_strlen(aString);
+  rv = Write32(length);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (length == 0) {
+    return NS_OK;
+  }
+  byteCount = length * sizeof(char16_t);
+
+#ifdef IS_BIG_ENDIAN
+  rv = WriteBytes(reinterpret_cast<const char*>(aString), byteCount);
+#else
+  // XXX use WriteSegments here to avoid copy!
+  char16_t* copy;
+  char16_t temp[64];
+  if (length <= 64) {
+    copy = temp;
+  } else {
+    copy = reinterpret_cast<char16_t*>(malloc(byteCount));
+    if (!copy) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+  }
+  NS_ASSERTION((uintptr_t(aString) & 0x1) == 0, "aString not properly aligned");
+  mozilla::NativeEndian::copyAndSwapToBigEndian(copy, aString, length);
+  rv = WriteBytes(reinterpret_cast<const char*>(copy), byteCount);
+  if (copy != temp) {
+    free(copy);
+  }
+#endif
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteUtf8Z(const char16_t* aString)
+{
+  return WriteStringZ(NS_ConvertUTF16toUTF8(aString).get());
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteBytes(const char* aString, uint32_t aLength)
+{
+  nsresult rv;
+  uint32_t bytesWritten;
+
+  rv = Write(aString, aLength, &bytesWritten);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (bytesWritten != aLength) {
+    return NS_ERROR_FAILURE;
+  }
+  return rv;
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteByteArray(uint8_t* aBytes, uint32_t aLength)
+{
+  return WriteBytes(reinterpret_cast<char*>(aBytes), aLength);
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteObject(nsISupports* aObject, bool aIsStrongRef)
+{
+  return WriteCompoundObject(aObject, NS_GET_IID(nsISupports),
+                             aIsStrongRef);
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteSingleRefObject(nsISupports* aObject)
+{
+  return WriteCompoundObject(aObject, NS_GET_IID(nsISupports),
+                             true);
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteCompoundObject(nsISupports* aObject,
+                                          const nsIID& aIID,
+                                          bool aIsStrongRef)
+{
+  nsCOMPtr<nsIClassInfo> classInfo = do_QueryInterface(aObject);
+  nsCOMPtr<nsISerializable> serializable = do_QueryInterface(aObject);
+
+  // Can't deal with weak refs
+  if (NS_WARN_IF(!aIsStrongRef)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  if (NS_WARN_IF(!classInfo) || NS_WARN_IF(!serializable)) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  nsCID cid;
+  nsresult rv = classInfo->GetClassIDNoAlloc(&cid);
+  if (NS_SUCCEEDED(rv)) {
+    rv = WriteID(cid);
+  } else {
+    nsCID* cidptr = nullptr;
+    rv = classInfo->GetClassID(&cidptr);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    rv = WriteID(*cidptr);
+
+    free(cidptr);
+  }
+
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = WriteID(aIID);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  return serializable->Write(this);
+}
+
+NS_IMETHODIMP
+nsBinaryOutputStream::WriteID(const nsIID& aIID)
+{
+  nsresult rv = Write32(aIID.m0);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = Write16(aIID.m1);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = Write16(aIID.m2);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  for (int i = 0; i < 8; ++i) {
+    rv = Write8(aIID.m3[i]);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP_(char*)
+nsBinaryOutputStream::GetBuffer(uint32_t aLength, uint32_t aAlignMask)
+{
+  if (mBufferAccess) {
+    return mBufferAccess->GetBuffer(aLength, aAlignMask);
+  }
+  return nullptr;
+}
+
+NS_IMETHODIMP_(void)
+nsBinaryOutputStream::PutBuffer(char* aBuffer, uint32_t aLength)
+{
+  if (mBufferAccess) {
+    mBufferAccess->PutBuffer(aBuffer, aLength);
+  }
+}
+
+NS_IMPL_ISUPPORTS(nsBinaryInputStream,
+                  nsIObjectInputStream,
+                  nsIBinaryInputStream,
+                  nsIInputStream)
+
+NS_IMETHODIMP
+nsBinaryInputStream::Available(uint64_t* aResult)
+{
+  if (NS_WARN_IF(!mInputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mInputStream->Available(aResult);
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::Read(char* aBuffer, uint32_t aCount, uint32_t* aNumRead)
+{
+  if (NS_WARN_IF(!mInputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  // mInputStream might give us short reads, so deal with that.
+  uint32_t totalRead = 0;
+
+  uint32_t bytesRead;
+  do {
+    nsresult rv = mInputStream->Read(aBuffer, aCount, &bytesRead);
+    if (rv == NS_BASE_STREAM_WOULD_BLOCK && totalRead != 0) {
+      // We already read some data.  Return it.
+      break;
+    }
+
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    totalRead += bytesRead;
+    aBuffer += bytesRead;
+    aCount -= bytesRead;
+  } while (aCount != 0 && bytesRead != 0);
+
+  *aNumRead = totalRead;
+
+  return NS_OK;
+}
+
+
+// when forwarding ReadSegments to mInputStream, we need to make sure
+// 'this' is being passed to the writer each time. To do this, we need
+// a thunking function which keeps the real input stream around.
+
+// the closure wrapper
+struct MOZ_STACK_CLASS ReadSegmentsClosure
+{
+  nsCOMPtr<nsIInputStream> mRealInputStream;
+  void* mRealClosure;
+  nsWriteSegmentFun mRealWriter;
+  nsresult mRealResult;
+  uint32_t mBytesRead;  // to properly implement aToOffset
+};
+
+// the thunking function
+static nsresult
+ReadSegmentForwardingThunk(nsIInputStream* aStream,
+                           void* aClosure,
+                           const char* aFromSegment,
+                           uint32_t aToOffset,
+                           uint32_t aCount,
+                           uint32_t* aWriteCount)
+{
+  ReadSegmentsClosure* thunkClosure =
+    reinterpret_cast<ReadSegmentsClosure*>(aClosure);
+
+  NS_ASSERTION(NS_SUCCEEDED(thunkClosure->mRealResult),
+               "How did this get to be a failure status?");
+
+  thunkClosure->mRealResult =
+    thunkClosure->mRealWriter(thunkClosure->mRealInputStream,
+                              thunkClosure->mRealClosure,
+                              aFromSegment,
+                              thunkClosure->mBytesRead + aToOffset,
+                              aCount, aWriteCount);
+
+  return thunkClosure->mRealResult;
+}
+
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
+                                  uint32_t aCount, uint32_t* aResult)
+{
+  if (NS_WARN_IF(!mInputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  ReadSegmentsClosure thunkClosure = { this, aClosure, aWriter, NS_OK, 0 };
+
+  // mInputStream might give us short reads, so deal with that.
+  uint32_t bytesRead;
+  do {
+    nsresult rv = mInputStream->ReadSegments(ReadSegmentForwardingThunk,
+                                             &thunkClosure,
+                                             aCount, &bytesRead);
+
+    if (rv == NS_BASE_STREAM_WOULD_BLOCK && thunkClosure.mBytesRead != 0) {
+      // We already read some data.  Return it.
+      break;
+    }
+
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    thunkClosure.mBytesRead += bytesRead;
+    aCount -= bytesRead;
+  } while (aCount != 0 && bytesRead != 0 &&
+           NS_SUCCEEDED(thunkClosure.mRealResult));
+
+  *aResult = thunkClosure.mBytesRead;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::IsNonBlocking(bool* aNonBlocking)
+{
+  if (NS_WARN_IF(!mInputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mInputStream->IsNonBlocking(aNonBlocking);
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::Close()
+{
+  if (NS_WARN_IF(!mInputStream)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mInputStream->Close();
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::SetInputStream(nsIInputStream* aInputStream)
+{
+  if (NS_WARN_IF(!aInputStream)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  mInputStream = aInputStream;
+  mBufferAccess = do_QueryInterface(aInputStream);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadBoolean(bool* aBoolean)
+{
+  uint8_t byteResult;
+  nsresult rv = Read8(&byteResult);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  *aBoolean = !!byteResult;
+  return rv;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::Read8(uint8_t* aByte)
+{
+  nsresult rv;
+  uint32_t bytesRead;
+
+  rv = Read(reinterpret_cast<char*>(aByte), sizeof(*aByte), &bytesRead);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (bytesRead != 1) {
+    return NS_ERROR_FAILURE;
+  }
+  return rv;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::Read16(uint16_t* aNum)
+{
+  uint32_t bytesRead;
+  nsresult rv = Read(reinterpret_cast<char*>(aNum), sizeof(*aNum), &bytesRead);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (bytesRead != sizeof(*aNum)) {
+    return NS_ERROR_FAILURE;
+  }
+  *aNum = mozilla::NativeEndian::swapFromBigEndian(*aNum);
+  return rv;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::Read32(uint32_t* aNum)
+{
+  uint32_t bytesRead;
+  nsresult rv = Read(reinterpret_cast<char*>(aNum), sizeof(*aNum), &bytesRead);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (bytesRead != sizeof(*aNum)) {
+    return NS_ERROR_FAILURE;
+  }
+  *aNum = mozilla::NativeEndian::swapFromBigEndian(*aNum);
+  return rv;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::Read64(uint64_t* aNum)
+{
+  uint32_t bytesRead;
+  nsresult rv = Read(reinterpret_cast<char*>(aNum), sizeof(*aNum), &bytesRead);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (bytesRead != sizeof(*aNum)) {
+    return NS_ERROR_FAILURE;
+  }
+  *aNum = mozilla::NativeEndian::swapFromBigEndian(*aNum);
+  return rv;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadFloat(float* aFloat)
+{
+  NS_ASSERTION(sizeof(float) == sizeof(uint32_t),
+               "False assumption about sizeof(float)");
+  return Read32(reinterpret_cast<uint32_t*>(aFloat));
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadDouble(double* aDouble)
+{
+  NS_ASSERTION(sizeof(double) == sizeof(uint64_t),
+               "False assumption about sizeof(double)");
+  return Read64(reinterpret_cast<uint64_t*>(aDouble));
+}
+
+static nsresult
+WriteSegmentToCString(nsIInputStream* aStream,
+                      void* aClosure,
+                      const char* aFromSegment,
+                      uint32_t aToOffset,
+                      uint32_t aCount,
+                      uint32_t* aWriteCount)
+{
+  nsACString* outString = static_cast<nsACString*>(aClosure);
+
+  outString->Append(aFromSegment, aCount);
+
+  *aWriteCount = aCount;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadCString(nsACString& aString)
+{
+  nsresult rv;
+  uint32_t length, bytesRead;
+
+  rv = Read32(&length);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  aString.Truncate();
+  rv = ReadSegments(WriteSegmentToCString, &aString, length, &bytesRead);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (bytesRead != length) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+
+// sometimes, WriteSegmentToString will be handed an odd-number of
+// bytes, which means we only have half of the last char16_t
+struct WriteStringClosure
+{
+  char16_t* mWriteCursor;
+  bool mHasCarryoverByte;
+  char mCarryoverByte;
+};
+
+// there are a few cases we have to account for here:
+// * even length buffer, no carryover - easy, just append
+// * odd length buffer, no carryover - the last byte needs to be saved
+//                                     for carryover
+// * odd length buffer, with carryover - first byte needs to be used
+//                              with the carryover byte, and
+//                              the rest of the even length
+//                              buffer is appended as normal
+// * even length buffer, with carryover - the first byte needs to be
+//                              used with the previous carryover byte.
+//                              this gives you an odd length buffer,
+//                              so you have to save the last byte for
+//                              the next carryover
+
+
+// same version of the above, but with correct casting and endian swapping
+static nsresult
+WriteSegmentToString(nsIInputStream* aStream,
+                     void* aClosure,
+                     const char* aFromSegment,
+                     uint32_t aToOffset,
+                     uint32_t aCount,
+                     uint32_t* aWriteCount)
+{
+  NS_PRECONDITION(aCount > 0, "Why are we being told to write 0 bytes?");
+  NS_PRECONDITION(sizeof(char16_t) == 2, "We can't handle other sizes!");
+
+  WriteStringClosure* closure = static_cast<WriteStringClosure*>(aClosure);
+  char16_t* cursor = closure->mWriteCursor;
+
+  // we're always going to consume the whole buffer no matter what
+  // happens, so take care of that right now.. that allows us to
+  // tweak aCount later. Do NOT move this!
+  *aWriteCount = aCount;
+
+  // if the last Write had an odd-number of bytes read, then
+  if (closure->mHasCarryoverByte) {
+    // re-create the two-byte sequence we want to work with
+    char bytes[2] = { closure->mCarryoverByte, *aFromSegment };
+    *cursor = *(char16_t*)bytes;
+    // Now the little endianness dance
+    mozilla::NativeEndian::swapToBigEndianInPlace(cursor, 1);
+    ++cursor;
+
+    // now skip past the first byte of the buffer.. code from here
+    // can assume normal operations, but should not assume aCount
+    // is relative to the ORIGINAL buffer
+    ++aFromSegment;
+    --aCount;
+
+    closure->mHasCarryoverByte = false;
+  }
+
+  // this array is possibly unaligned... be careful how we access it!
+  const char16_t* unicodeSegment =
+    reinterpret_cast<const char16_t*>(aFromSegment);
+
+  // calculate number of full characters in segment (aCount could be odd!)
+  uint32_t segmentLength = aCount / sizeof(char16_t);
+
+  // copy all data into our aligned buffer.  byte swap if necessary.
+  // cursor may be unaligned, so we cannot use copyAndSwapToBigEndian directly
+  memcpy(cursor, unicodeSegment, segmentLength * sizeof(char16_t));
+  char16_t* end = cursor + segmentLength;
+  mozilla::NativeEndian::swapToBigEndianInPlace(cursor, segmentLength);
+  closure->mWriteCursor = end;
+
+  // remember this is the modifed aCount and aFromSegment,
+  // so that will take into account the fact that we might have
+  // skipped the first byte in the buffer
+  if (aCount % sizeof(char16_t) != 0) {
+    // we must have had a carryover byte, that we'll need the next
+    // time around
+    closure->mCarryoverByte = aFromSegment[aCount - 1];
+    closure->mHasCarryoverByte = true;
+  }
+
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadString(nsAString& aString)
+{
+  nsresult rv;
+  uint32_t length, bytesRead;
+
+  rv = Read32(&length);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (length == 0) {
+    aString.Truncate();
+    return NS_OK;
+  }
+
+  // pre-allocate output buffer, and get direct access to buffer...
+  if (!aString.SetLength(length, mozilla::fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  nsAString::iterator start;
+  aString.BeginWriting(start);
+
+  WriteStringClosure closure;
+  closure.mWriteCursor = start.get();
+  closure.mHasCarryoverByte = false;
+
+  rv = ReadSegments(WriteSegmentToString, &closure,
+                    length * sizeof(char16_t), &bytesRead);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  NS_ASSERTION(!closure.mHasCarryoverByte, "some strange stream corruption!");
+
+  if (bytesRead != length * sizeof(char16_t)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadBytes(uint32_t aLength, char** aResult)
+{
+  nsresult rv;
+  uint32_t bytesRead;
+  char* s;
+
+  s = reinterpret_cast<char*>(malloc(aLength));
+  if (!s) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  rv = Read(s, aLength, &bytesRead);
+  if (NS_FAILED(rv)) {
+    free(s);
+    return rv;
+  }
+  if (bytesRead != aLength) {
+    free(s);
+    return NS_ERROR_FAILURE;
+  }
+
+  *aResult = s;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadByteArray(uint32_t aLength, uint8_t** aResult)
+{
+  return ReadBytes(aLength, reinterpret_cast<char**>(aResult));
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadArrayBuffer(uint32_t aLength,
+                                     JS::Handle<JS::Value> aBuffer,
+                                     JSContext* aCx, uint32_t* aReadLength)
+{
+  if (!aBuffer.isObject()) {
+    return NS_ERROR_FAILURE;
+  }
+  JS::RootedObject buffer(aCx, &aBuffer.toObject());
+  if (!JS_IsArrayBufferObject(buffer)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  uint32_t bufferLength = JS_GetArrayBufferByteLength(buffer);
+  if (bufferLength < aLength) {
+    return NS_ERROR_FAILURE;
+  }
+
+  uint32_t bufSize = std::min<uint32_t>(aLength, 4096);
+  UniquePtr<char[]> buf = MakeUnique<char[]>(bufSize);
+
+  uint32_t pos = 0;
+  *aReadLength = 0;
+  do {
+    // Read data into temporary buffer.
+    uint32_t bytesRead;
+    uint32_t amount = std::min(aLength - pos, bufSize);
+    nsresult rv = Read(buf.get(), amount, &bytesRead);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+    MOZ_ASSERT(bytesRead <= amount);
+
+    if (bytesRead == 0) {
+      break;
+    }
+
+    // Copy data into actual buffer.
+
+    JS::AutoCheckCannotGC nogc;
+    bool isShared;
+    if (bufferLength != JS_GetArrayBufferByteLength(buffer)) {
+      return NS_ERROR_FAILURE;
+    }
+
+    char* data = reinterpret_cast<char*>(JS_GetArrayBufferData(buffer, &isShared, nogc));
+    MOZ_ASSERT(!isShared);      // Implied by JS_GetArrayBufferData()
+    if (!data) {
+      return NS_ERROR_FAILURE;
+    }
+
+    *aReadLength += bytesRead;
+    PodCopy(data + pos, buf.get(), bytesRead);
+
+    pos += bytesRead;
+  } while (pos < aLength);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadObject(bool aIsStrongRef, nsISupports** aObject)
+{
+  nsCID cid;
+  nsIID iid;
+  nsresult rv = ReadID(&cid);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = ReadID(&iid);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  // HACK: Intercept old (pre-gecko6) nsIURI IID, and replace with
+  // the updated IID, so that we're QI'ing to an actual interface.
+  // (As soon as we drop support for upgrading from pre-gecko6, we can
+  // remove this chunk.)
+  static const nsIID oldURIiid = {
+    0x7a22cc0, 0xce5, 0x11d3,
+    { 0x93, 0x31, 0x0, 0x10, 0x4b, 0xa0, 0xfd, 0x40 }
+  };
+
+  // hackaround for bug 670542
+  static const nsIID oldURIiid2 = {
+    0xd6d04c36, 0x0fa4, 0x4db3,
+    { 0xbe, 0x05, 0x4a, 0x18, 0x39, 0x71, 0x03, 0xe2 }
+  };
+
+  // hackaround for bug 682031
+  static const nsIID oldURIiid3 = {
+    0x12120b20, 0x0929, 0x40e9,
+    { 0x88, 0xcf, 0x6e, 0x08, 0x76, 0x6e, 0x8b, 0x23 }
+  };
+
+  // hackaround for bug 1195415
+  static const nsIID oldURIiid4 = {
+    0x395fe045, 0x7d18, 0x4adb,
+    { 0xa3, 0xfd, 0xaf, 0x98, 0xc8, 0xa1, 0xaf, 0x11 }
+  };
+
+  if (iid.Equals(oldURIiid) ||
+      iid.Equals(oldURIiid2) ||
+      iid.Equals(oldURIiid3) ||
+      iid.Equals(oldURIiid4)) {
+    const nsIID newURIiid = NS_IURI_IID;
+    iid = newURIiid;
+  }
+  // END HACK
+
+  // HACK:  Service workers store resource security info on disk in the dom
+  //        Cache API.  When the uuid of the nsIX509Cert interface changes
+  //        these serialized objects cannot be loaded any more.  This hack
+  //        works around this issue.
+
+  // hackaround for bug 1247580 (FF45 to FF46 transition)
+  static const nsIID oldCertIID = {
+    0xf8ed8364, 0xced9, 0x4c6e,
+    { 0x86, 0xba, 0x48, 0xaf, 0x53, 0xc3, 0x93, 0xe6 }
+  };
+
+  if (iid.Equals(oldCertIID)) {
+    const nsIID newCertIID = NS_IX509CERT_IID;
+    iid = newCertIID;
+  }
+  // END HACK
+
+  nsCOMPtr<nsISupports> object = do_CreateInstance(cid, &rv);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  nsCOMPtr<nsISerializable> serializable = do_QueryInterface(object);
+  if (NS_WARN_IF(!serializable)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  rv = serializable->Read(this);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  return object->QueryInterface(iid, reinterpret_cast<void**>(aObject));
+}
+
+NS_IMETHODIMP
+nsBinaryInputStream::ReadID(nsID* aResult)
+{
+  nsresult rv = Read32(&aResult->m0);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = Read16(&aResult->m1);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = Read16(&aResult->m2);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  for (int i = 0; i < 8; ++i) {
+    rv = Read8(&aResult->m3[i]);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP_(char*)
+nsBinaryInputStream::GetBuffer(uint32_t aLength, uint32_t aAlignMask)
+{
+  if (mBufferAccess) {
+    return mBufferAccess->GetBuffer(aLength, aAlignMask);
+  }
+  return nullptr;
+}
+
+NS_IMETHODIMP_(void)
+nsBinaryInputStream::PutBuffer(char* aBuffer, uint32_t aLength)
+{
+  if (mBufferAccess) {
+    mBufferAccess->PutBuffer(aBuffer, aLength);
+  }
+}
diff --git a/xpcom/io/nsBinaryStream.h b/xpcom/io/nsBinaryStream.h
new file mode 100644
index 000000000..2520d9201
--- /dev/null
+++ b/xpcom/io/nsBinaryStream.h
@@ -0,0 +1,101 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsBinaryStream_h___
+#define nsBinaryStream_h___
+
+#include "nsCOMPtr.h"
+#include "nsAString.h"
+#include "nsIObjectInputStream.h"
+#include "nsIObjectOutputStream.h"
+#include "nsIStreamBufferAccess.h"
+
+#define NS_BINARYOUTPUTSTREAM_CID        \
+{ /* 86c37b9a-74e7-4672-844e-6e7dd83ba484 */         \
+     0x86c37b9a,                                     \
+     0x74e7,                                         \
+     0x4672,                                         \
+    {0x84, 0x4e, 0x6e, 0x7d, 0xd8, 0x3b, 0xa4, 0x84} \
+}
+
+#define NS_BINARYOUTPUTSTREAM_CONTRACTID "@mozilla.org/binaryoutputstream;1"
+
+// Derive from nsIObjectOutputStream so this class can be used as a superclass
+// by nsObjectOutputStream.
+class nsBinaryOutputStream final : public nsIObjectOutputStream
+{
+public:
+  nsBinaryOutputStream()
+  {
+  }
+
+protected:
+  // nsISupports methods
+  NS_DECL_ISUPPORTS
+
+  // nsIOutputStream methods
+  NS_DECL_NSIOUTPUTSTREAM
+
+  // nsIBinaryOutputStream methods
+  NS_DECL_NSIBINARYOUTPUTSTREAM
+
+  // nsIObjectOutputStream methods
+  NS_DECL_NSIOBJECTOUTPUTSTREAM
+
+  // Call Write(), ensuring that all proffered data is written
+  nsresult WriteFully(const char* aBuf, uint32_t aCount);
+
+  nsCOMPtr<nsIOutputStream>       mOutputStream;
+  nsCOMPtr<nsIStreamBufferAccess> mBufferAccess;
+
+private:
+  // virtual dtor since subclasses call our Release()
+  virtual ~nsBinaryOutputStream()
+  {
+  }
+};
+
+#define NS_BINARYINPUTSTREAM_CID        \
+{ /* c521a612-2aad-46db-b6ab-3b821fb150b1 */       \
+   0xc521a612,                                     \
+   0x2aad,                                         \
+   0x46db,                                         \
+  {0xb6, 0xab, 0x3b, 0x82, 0x1f, 0xb1, 0x50, 0xb1} \
+}
+
+#define NS_BINARYINPUTSTREAM_CONTRACTID "@mozilla.org/binaryinputstream;1"
+
+class nsBinaryInputStream final : public nsIObjectInputStream
+{
+public:
+  nsBinaryInputStream()
+  {
+  }
+
+protected:
+  // nsISupports methods
+  NS_DECL_ISUPPORTS
+
+  // nsIInputStream methods
+  NS_DECL_NSIINPUTSTREAM
+
+  // nsIBinaryInputStream methods
+  NS_DECL_NSIBINARYINPUTSTREAM
+
+  // nsIObjectInputStream methods
+  NS_DECL_NSIOBJECTINPUTSTREAM
+
+  nsCOMPtr<nsIInputStream>        mInputStream;
+  nsCOMPtr<nsIStreamBufferAccess> mBufferAccess;
+
+private:
+  // virtual dtor since subclasses call our Release()
+  virtual ~nsBinaryInputStream()
+  {
+  }
+};
+
+#endif // nsBinaryStream_h___
diff --git a/xpcom/io/nsDirectoryService.cpp b/xpcom/io/nsDirectoryService.cpp
new file mode 100644
index 000000000..a4d962395
--- /dev/null
+++ b/xpcom/io/nsDirectoryService.cpp
@@ -0,0 +1,766 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ArrayUtils.h"
+
+#include "nsCOMPtr.h"
+#include "nsAutoPtr.h"
+#include "nsDirectoryService.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsLocalFile.h"
+#include "nsDebug.h"
+#include "nsStaticAtom.h"
+#include "nsEnumeratorUtils.h"
+
+#include "nsICategoryManager.h"
+#include "nsISimpleEnumerator.h"
+#include "nsIStringEnumerator.h"
+
+#if defined(XP_WIN)
+#include <windows.h>
+#include <shlobj.h>
+#include <stdlib.h>
+#include <stdio.h>
+#elif defined(XP_UNIX)
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/param.h>
+#include "prenv.h"
+#ifdef MOZ_WIDGET_COCOA
+#include <CoreServices/CoreServices.h>
+#include <Carbon/Carbon.h>
+#endif
+#endif
+
+#include "SpecialSystemDirectory.h"
+#include "nsAppFileLocationProvider.h"
+
+using namespace mozilla;
+
+// define home directory
+// For Windows platform, We are choosing Appdata folder as HOME
+#if defined (XP_WIN)
+#define HOME_DIR NS_WIN_APPDATA_DIR
+#elif defined (MOZ_WIDGET_COCOA)
+#define HOME_DIR NS_OSX_HOME_DIR
+#elif defined (XP_UNIX)
+#define HOME_DIR NS_UNIX_HOME_DIR
+#endif
+
+//----------------------------------------------------------------------------------------
+nsresult
+nsDirectoryService::GetCurrentProcessDirectory(nsIFile** aFile)
+//----------------------------------------------------------------------------------------
+{
+  if (NS_WARN_IF(!aFile)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  *aFile = nullptr;
+
+  //  Set the component registry location:
+  if (!gService) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsresult rv;
+
+  nsCOMPtr<nsIProperties> dirService;
+  rv = nsDirectoryService::Create(nullptr,
+                                  NS_GET_IID(nsIProperties),
+                                  getter_AddRefs(dirService));  // needs to be around for life of product
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (dirService) {
+    nsCOMPtr<nsIFile> localFile;
+    dirService->Get(NS_XPCOM_INIT_CURRENT_PROCESS_DIR, NS_GET_IID(nsIFile),
+                    getter_AddRefs(localFile));
+    if (localFile) {
+      localFile.forget(aFile);
+      return NS_OK;
+    }
+  }
+
+  RefPtr<nsLocalFile> localFile = new nsLocalFile;
+
+#ifdef XP_WIN
+  wchar_t buf[MAX_PATH + 1];
+  SetLastError(ERROR_SUCCESS);
+  if (GetModuleFileNameW(0, buf, mozilla::ArrayLength(buf)) &&
+      GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
+    // chop off the executable name by finding the rightmost backslash
+    wchar_t* lastSlash = wcsrchr(buf, L'\\');
+    if (lastSlash) {
+      *(lastSlash + 1) = L'\0';
+    }
+
+    localFile->InitWithPath(nsDependentString(buf));
+    localFile.forget(aFile);
+    return NS_OK;
+  }
+
+#elif defined(MOZ_WIDGET_COCOA)
+  // Works even if we're not bundled.
+  CFBundleRef appBundle = CFBundleGetMainBundle();
+  if (appBundle) {
+    CFURLRef bundleURL = CFBundleCopyExecutableURL(appBundle);
+    if (bundleURL) {
+      CFURLRef parentURL = CFURLCreateCopyDeletingLastPathComponent(
+        kCFAllocatorDefault, bundleURL);
+      if (parentURL) {
+        // Pass true for the "resolveAgainstBase" arg to CFURLGetFileSystemRepresentation.
+        // This will resolve the relative portion of the CFURL against it base, giving a full
+        // path, which CFURLCopyFileSystemPath doesn't do.
+        char buffer[PATH_MAX];
+        if (CFURLGetFileSystemRepresentation(parentURL, true,
+                                             (UInt8*)buffer, sizeof(buffer))) {
+#ifdef DEBUG_conrad
+          printf("nsDirectoryService - CurrentProcessDir is: %s\n", buffer);
+#endif
+          rv = localFile->InitWithNativePath(nsDependentCString(buffer));
+          if (NS_SUCCEEDED(rv)) {
+            localFile.forget(aFile);
+          }
+        }
+        CFRelease(parentURL);
+      }
+      CFRelease(bundleURL);
+    }
+  }
+
+  NS_ASSERTION(*aFile, "nsDirectoryService - Could not determine CurrentProcessDir.\n");
+  if (*aFile) {
+    return NS_OK;
+  }
+
+#elif defined(XP_UNIX)
+
+  // In the absence of a good way to get the executable directory let
+  // us try this for unix:
+  //    - if MOZILLA_FIVE_HOME is defined, that is it
+  //    - else give the current directory
+  char buf[MAXPATHLEN];
+
+  // The MOZ_DEFAULT_MOZILLA_FIVE_HOME variable can be set at configure time with
+  // a --with-default-mozilla-five-home=foo autoconf flag.
+  //
+  // The idea here is to allow for builds that have a default MOZILLA_FIVE_HOME
+  // regardless of the environment.  This makes it easier to write apps that
+  // embed mozilla without having to worry about setting up the environment
+  //
+  // We do this by putenv()ing the default value into the environment.  Note that
+  // we only do this if it is not already set.
+#ifdef MOZ_DEFAULT_MOZILLA_FIVE_HOME
+  const char* home = PR_GetEnv("MOZILLA_FIVE_HOME");
+  if (!home || !*home) {
+    putenv("MOZILLA_FIVE_HOME=" MOZ_DEFAULT_MOZILLA_FIVE_HOME);
+  }
+#endif
+
+  char* moz5 = PR_GetEnv("MOZILLA_FIVE_HOME");
+  if (moz5 && *moz5) {
+    if (realpath(moz5, buf)) {
+      localFile->InitWithNativePath(nsDependentCString(buf));
+      localFile.forget(aFile);
+      return NS_OK;
+    }
+  }
+#if defined(DEBUG)
+  static bool firstWarning = true;
+
+  if ((!moz5 || !*moz5) && firstWarning) {
+    // Warn that MOZILLA_FIVE_HOME not set, once.
+    printf("Warning: MOZILLA_FIVE_HOME not set.\n");
+    firstWarning = false;
+  }
+#endif /* DEBUG */
+
+  // Fall back to current directory.
+  if (getcwd(buf, sizeof(buf))) {
+    localFile->InitWithNativePath(nsDependentCString(buf));
+    localFile.forget(aFile);
+    return NS_OK;
+  }
+
+#endif
+
+  NS_ERROR("unable to get current process directory");
+  return NS_ERROR_FAILURE;
+} // GetCurrentProcessDirectory()
+
+StaticRefPtr<nsDirectoryService> nsDirectoryService::gService;
+
+nsDirectoryService::nsDirectoryService()
+  : mHashtable(128)
+{
+}
+
+nsresult
+nsDirectoryService::Create(nsISupports* aOuter, REFNSIID aIID, void** aResult)
+{
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  if (NS_WARN_IF(aOuter)) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+
+  if (!gService) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  return gService->QueryInterface(aIID, aResult);
+}
+
+#define DIR_ATOM(name_, value_) nsIAtom* nsDirectoryService::name_ = nullptr;
+#include "nsDirectoryServiceAtomList.h"
+#undef DIR_ATOM
+
+#define DIR_ATOM(name_, value_) NS_STATIC_ATOM_BUFFER(name_##_buffer, value_)
+#include "nsDirectoryServiceAtomList.h"
+#undef DIR_ATOM
+
+static const nsStaticAtom directory_atoms[] = {
+#define DIR_ATOM(name_, value_) NS_STATIC_ATOM(name_##_buffer, &nsDirectoryService::name_),
+#include "nsDirectoryServiceAtomList.h"
+#undef DIR_ATOM
+};
+
+NS_IMETHODIMP
+nsDirectoryService::Init()
+{
+  NS_NOTREACHED("nsDirectoryService::Init() for internal use only!");
+  return NS_OK;
+}
+
+void
+nsDirectoryService::RealInit()
+{
+  NS_ASSERTION(!gService,
+               "nsDirectoryService::RealInit Mustn't initialize twice!");
+
+  gService = new nsDirectoryService();
+
+  NS_RegisterStaticAtoms(directory_atoms);
+
+  // Let the list hold the only reference to the provider.
+  nsAppFileLocationProvider* defaultProvider = new nsAppFileLocationProvider;
+  gService->mProviders.AppendElement(defaultProvider);
+}
+
+nsDirectoryService::~nsDirectoryService()
+{
+}
+
+NS_IMPL_ISUPPORTS(nsDirectoryService,
+                  nsIProperties,
+                  nsIDirectoryService,
+                  nsIDirectoryServiceProvider,
+                  nsIDirectoryServiceProvider2)
+
+
+NS_IMETHODIMP
+nsDirectoryService::Undefine(const char* aProp)
+{
+  if (NS_WARN_IF(!aProp)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsDependentCString key(aProp);
+  if (!mHashtable.Get(key, nullptr)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  mHashtable.Remove(key);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDirectoryService::GetKeys(uint32_t* aCount, char*** aKeys)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+struct MOZ_STACK_CLASS FileData
+{
+  FileData(const char* aProperty, const nsIID& aUUID)
+    : property(aProperty)
+    , data(nullptr)
+    , persistent(true)
+    , uuid(aUUID)
+  {
+  }
+
+  const char*   property;
+  nsCOMPtr<nsISupports> data;
+  bool          persistent;
+  const nsIID&  uuid;
+};
+
+static bool
+FindProviderFile(nsIDirectoryServiceProvider* aElement, FileData* aData)
+{
+  nsresult rv;
+  if (aData->uuid.Equals(NS_GET_IID(nsISimpleEnumerator))) {
+    // Not all providers implement this iface
+    nsCOMPtr<nsIDirectoryServiceProvider2> prov2 = do_QueryInterface(aElement);
+    if (prov2) {
+      nsCOMPtr<nsISimpleEnumerator> newFiles;
+      rv = prov2->GetFiles(aData->property, getter_AddRefs(newFiles));
+      if (NS_SUCCEEDED(rv) && newFiles) {
+        if (aData->data) {
+          nsCOMPtr<nsISimpleEnumerator> unionFiles;
+
+          NS_NewUnionEnumerator(getter_AddRefs(unionFiles),
+                                (nsISimpleEnumerator*)aData->data.get(), newFiles);
+
+          if (unionFiles) {
+            unionFiles.swap(*(nsISimpleEnumerator**)&aData->data);
+          }
+        } else {
+          aData->data = newFiles;
+        }
+
+        aData->persistent = false; // Enumerators can never be persistent
+        return rv == NS_SUCCESS_AGGREGATE_RESULT;
+      }
+    }
+  } else {
+    rv = aElement->GetFile(aData->property, &aData->persistent,
+                           (nsIFile**)&aData->data);
+    if (NS_SUCCEEDED(rv) && aData->data) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+NS_IMETHODIMP
+nsDirectoryService::Get(const char* aProp, const nsIID& aUuid, void** aResult)
+{
+  if (NS_WARN_IF(!aProp)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsDependentCString key(aProp);
+
+  nsCOMPtr<nsIFile> cachedFile = mHashtable.Get(key);
+
+  if (cachedFile) {
+    nsCOMPtr<nsIFile> cloneFile;
+    cachedFile->Clone(getter_AddRefs(cloneFile));
+    return cloneFile->QueryInterface(aUuid, aResult);
+  }
+
+  // it is not one of our defaults, lets check any providers
+  FileData fileData(aProp, aUuid);
+
+  for (int32_t i = mProviders.Length() - 1; i >= 0; i--) {
+    if (!FindProviderFile(mProviders[i], &fileData)) {
+      break;
+    }
+  }
+  if (fileData.data) {
+    if (fileData.persistent) {
+      Set(aProp, static_cast<nsIFile*>(fileData.data.get()));
+    }
+    nsresult rv = (fileData.data)->QueryInterface(aUuid, aResult);
+    fileData.data = nullptr; // AddRef occurs in FindProviderFile()
+    return rv;
+  }
+
+  FindProviderFile(static_cast<nsIDirectoryServiceProvider*>(this), &fileData);
+  if (fileData.data) {
+    if (fileData.persistent) {
+      Set(aProp, static_cast<nsIFile*>(fileData.data.get()));
+    }
+    nsresult rv = (fileData.data)->QueryInterface(aUuid, aResult);
+    fileData.data = nullptr; // AddRef occurs in FindProviderFile()
+    return rv;
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsDirectoryService::Set(const char* aProp, nsISupports* aValue)
+{
+  if (NS_WARN_IF(!aProp)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsDependentCString key(aProp);
+  if (mHashtable.Get(key, nullptr) || !aValue) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsCOMPtr<nsIFile> ourFile = do_QueryInterface(aValue);
+  if (ourFile) {
+    nsCOMPtr<nsIFile> cloneFile;
+    ourFile->Clone(getter_AddRefs(cloneFile));
+    mHashtable.Put(key, cloneFile);
+
+    return NS_OK;
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsDirectoryService::Has(const char* aProp, bool* aResult)
+{
+  if (NS_WARN_IF(!aProp)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  *aResult = false;
+  nsCOMPtr<nsIFile> value;
+  nsresult rv = Get(aProp, NS_GET_IID(nsIFile), getter_AddRefs(value));
+  if (NS_FAILED(rv)) {
+    return NS_OK;
+  }
+
+  if (value) {
+    *aResult = true;
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsDirectoryService::RegisterProvider(nsIDirectoryServiceProvider* aProv)
+{
+  if (!aProv) {
+    return NS_ERROR_FAILURE;
+  }
+
+  mProviders.AppendElement(aProv);
+  return NS_OK;
+}
+
+void
+nsDirectoryService::RegisterCategoryProviders()
+{
+  nsCOMPtr<nsICategoryManager> catman
+  (do_GetService(NS_CATEGORYMANAGER_CONTRACTID));
+  if (!catman) {
+    return;
+  }
+
+  nsCOMPtr<nsISimpleEnumerator> entries;
+  catman->EnumerateCategory(XPCOM_DIRECTORY_PROVIDER_CATEGORY,
+                            getter_AddRefs(entries));
+
+  nsCOMPtr<nsIUTF8StringEnumerator> strings(do_QueryInterface(entries));
+  if (!strings) {
+    return;
+  }
+
+  bool more;
+  while (NS_SUCCEEDED(strings->HasMore(&more)) && more) {
+    nsAutoCString entry;
+    strings->GetNext(entry);
+
+    nsXPIDLCString contractID;
+    catman->GetCategoryEntry(XPCOM_DIRECTORY_PROVIDER_CATEGORY, entry.get(),
+                             getter_Copies(contractID));
+
+    if (contractID) {
+      nsCOMPtr<nsIDirectoryServiceProvider> provider = do_GetService(contractID.get());
+      if (provider) {
+        RegisterProvider(provider);
+      }
+    }
+  }
+}
+
+NS_IMETHODIMP
+nsDirectoryService::UnregisterProvider(nsIDirectoryServiceProvider* aProv)
+{
+  if (!aProv) {
+    return NS_ERROR_FAILURE;
+  }
+
+  mProviders.RemoveElement(aProv);
+  return NS_OK;
+}
+
+#if defined(MOZ_CONTENT_SANDBOX) && defined(XP_WIN)
+static nsresult
+GetLowIntegrityTempBase(nsIFile** aLowIntegrityTempBase)
+{
+  nsCOMPtr<nsIFile> localFile;
+  nsresult rv = GetSpecialSystemDirectory(Win_LocalAppdataLow,
+                                          getter_AddRefs(localFile));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = localFile->Append(NS_LITERAL_STRING(MOZ_USER_DIR));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  localFile.forget(aLowIntegrityTempBase);
+  return rv;
+}
+#endif
+
+// DO NOT ADD ANY LOCATIONS TO THIS FUNCTION UNTIL YOU TALK TO: dougt@netscape.com.
+// This is meant to be a place of xpcom or system specific file locations, not
+// application specific locations.  If you need the later, register a callback for
+// your application.
+
+NS_IMETHODIMP
+nsDirectoryService::GetFile(const char* aProp, bool* aPersistent,
+                            nsIFile** aResult)
+{
+  nsCOMPtr<nsIFile> localFile;
+  nsresult rv = NS_ERROR_FAILURE;
+
+  *aResult = nullptr;
+  *aPersistent = true;
+
+  nsCOMPtr<nsIAtom> inAtom = NS_Atomize(aProp);
+
+  // check to see if it is one of our defaults
+
+  if (inAtom == nsDirectoryService::sCurrentProcess ||
+      inAtom == nsDirectoryService::sOS_CurrentProcessDirectory) {
+    rv = GetCurrentProcessDirectory(getter_AddRefs(localFile));
+  }
+
+  // Unless otherwise set, the core pieces of the GRE exist
+  // in the current process directory.
+  else if (inAtom == nsDirectoryService::sGRE_Directory ||
+           inAtom == nsDirectoryService::sGRE_BinDirectory) {
+    rv = GetCurrentProcessDirectory(getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sOS_DriveDirectory) {
+    rv = GetSpecialSystemDirectory(OS_DriveDirectory, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sOS_TemporaryDirectory) {
+    rv = GetSpecialSystemDirectory(OS_TemporaryDirectory, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sOS_CurrentProcessDirectory) {
+    rv = GetSpecialSystemDirectory(OS_CurrentProcessDirectory, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sOS_CurrentWorkingDirectory) {
+    rv = GetSpecialSystemDirectory(OS_CurrentWorkingDirectory, getter_AddRefs(localFile));
+  }
+
+#if defined(MOZ_WIDGET_COCOA)
+  else if (inAtom == nsDirectoryService::sDirectory) {
+    rv = GetOSXFolderType(kClassicDomain, kSystemFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sTrashDirectory) {
+    rv = GetOSXFolderType(kClassicDomain, kTrashFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sStartupDirectory) {
+    rv = GetOSXFolderType(kClassicDomain, kStartupFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sShutdownDirectory) {
+    rv = GetOSXFolderType(kClassicDomain, kShutdownFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sAppleMenuDirectory) {
+    rv = GetOSXFolderType(kClassicDomain, kAppleMenuFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sControlPanelDirectory) {
+    rv = GetOSXFolderType(kClassicDomain, kControlPanelFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sExtensionDirectory) {
+    rv = GetOSXFolderType(kClassicDomain, kExtensionFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sFontsDirectory) {
+    rv = GetOSXFolderType(kClassicDomain, kFontsFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sPreferencesDirectory) {
+    rv = GetOSXFolderType(kClassicDomain, kPreferencesFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sDocumentsDirectory) {
+    rv = GetOSXFolderType(kClassicDomain, kDocumentsFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sInternetSearchDirectory) {
+    rv = GetOSXFolderType(kClassicDomain, kInternetSearchSitesFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sUserLibDirectory) {
+    rv = GetOSXFolderType(kUserDomain, kDomainLibraryFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sOS_HomeDirectory) {
+    rv = GetOSXFolderType(kUserDomain, kDomainTopLevelFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sDefaultDownloadDirectory) {
+    // 10.5 and later, we can use kDownloadsFolderType which is defined in
+    // Folders.h as "down".  However, in order to support 10.4 still, we
+    // cannot use the named constant.  We'll use it's value, and if it
+    // fails, fall back to the desktop.
+#ifndef kDownloadsFolderType
+#define kDownloadsFolderType 'down'
+#endif
+
+    rv = GetOSXFolderType(kUserDomain, kDownloadsFolderType,
+                          getter_AddRefs(localFile));
+    if (NS_FAILED(rv)) {
+      rv = GetOSXFolderType(kUserDomain, kDesktopFolderType,
+                            getter_AddRefs(localFile));
+    }
+  } else if (inAtom == nsDirectoryService::sUserDesktopDirectory ||
+             inAtom == nsDirectoryService::sOS_DesktopDirectory) {
+    rv = GetOSXFolderType(kUserDomain, kDesktopFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sLocalDesktopDirectory) {
+    rv = GetOSXFolderType(kLocalDomain, kDesktopFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sUserApplicationsDirectory) {
+    rv = GetOSXFolderType(kUserDomain, kApplicationsFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sLocalApplicationsDirectory) {
+    rv = GetOSXFolderType(kLocalDomain, kApplicationsFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sUserDocumentsDirectory) {
+    rv = GetOSXFolderType(kUserDomain, kDocumentsFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sLocalDocumentsDirectory) {
+    rv = GetOSXFolderType(kLocalDomain, kDocumentsFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sUserInternetPlugInDirectory) {
+    rv = GetOSXFolderType(kUserDomain, kInternetPlugInFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sLocalInternetPlugInDirectory) {
+    rv = GetOSXFolderType(kLocalDomain, kInternetPlugInFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sUserFrameworksDirectory) {
+    rv = GetOSXFolderType(kUserDomain, kFrameworksFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sLocalFrameworksDirectory) {
+    rv = GetOSXFolderType(kLocalDomain, kFrameworksFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sUserPreferencesDirectory) {
+    rv = GetOSXFolderType(kUserDomain, kPreferencesFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sLocalPreferencesDirectory) {
+    rv = GetOSXFolderType(kLocalDomain, kPreferencesFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sPictureDocumentsDirectory) {
+    rv = GetOSXFolderType(kUserDomain, kPictureDocumentsFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sMovieDocumentsDirectory) {
+    rv = GetOSXFolderType(kUserDomain, kMovieDocumentsFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sMusicDocumentsDirectory) {
+    rv = GetOSXFolderType(kUserDomain, kMusicDocumentsFolderType, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sInternetSitesDirectory) {
+    rv = GetOSXFolderType(kUserDomain, kInternetSitesFolderType, getter_AddRefs(localFile));
+  }
+#elif defined (XP_WIN)
+  else if (inAtom == nsDirectoryService::sSystemDirectory) {
+    rv = GetSpecialSystemDirectory(Win_SystemDirectory, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sWindowsDirectory) {
+    rv = GetSpecialSystemDirectory(Win_WindowsDirectory, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sWindowsProgramFiles) {
+    rv = GetSpecialSystemDirectory(Win_ProgramFiles, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sOS_HomeDirectory) {
+    rv = GetSpecialSystemDirectory(Win_HomeDirectory, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sDesktop) {
+    rv = GetSpecialSystemDirectory(Win_Desktop, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sPrograms) {
+    rv = GetSpecialSystemDirectory(Win_Programs, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sControls) {
+    rv = GetSpecialSystemDirectory(Win_Controls, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sPrinters) {
+    rv = GetSpecialSystemDirectory(Win_Printers, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sPersonal) {
+    rv = GetSpecialSystemDirectory(Win_Personal, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sFavorites) {
+    rv = GetSpecialSystemDirectory(Win_Favorites, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sStartup) {
+    rv = GetSpecialSystemDirectory(Win_Startup, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sRecent) {
+    rv = GetSpecialSystemDirectory(Win_Recent, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sSendto) {
+    rv = GetSpecialSystemDirectory(Win_Sendto, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sBitbucket) {
+    rv = GetSpecialSystemDirectory(Win_Bitbucket, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sStartmenu) {
+    rv = GetSpecialSystemDirectory(Win_Startmenu, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sDesktopdirectory ||
+             inAtom == nsDirectoryService::sOS_DesktopDirectory) {
+    rv = GetSpecialSystemDirectory(Win_Desktopdirectory, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sDrives) {
+    rv = GetSpecialSystemDirectory(Win_Drives, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sNetwork) {
+    rv = GetSpecialSystemDirectory(Win_Network, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sNethood) {
+    rv = GetSpecialSystemDirectory(Win_Nethood, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sFonts) {
+    rv = GetSpecialSystemDirectory(Win_Fonts, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sTemplates) {
+    rv = GetSpecialSystemDirectory(Win_Templates, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sCommon_Startmenu) {
+    rv = GetSpecialSystemDirectory(Win_Common_Startmenu, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sCommon_Programs) {
+    rv = GetSpecialSystemDirectory(Win_Common_Programs, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sCommon_Startup) {
+    rv = GetSpecialSystemDirectory(Win_Common_Startup, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sCommon_Desktopdirectory) {
+    rv = GetSpecialSystemDirectory(Win_Common_Desktopdirectory, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sCommon_AppData) {
+    rv = GetSpecialSystemDirectory(Win_Common_AppData, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sAppdata) {
+    rv = GetSpecialSystemDirectory(Win_Appdata, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sLocalAppdata) {
+    rv = GetSpecialSystemDirectory(Win_LocalAppdata, getter_AddRefs(localFile));
+#if defined(MOZ_CONTENT_SANDBOX)
+  } else if (inAtom == nsDirectoryService::sLocalAppdataLow) {
+    rv = GetSpecialSystemDirectory(Win_LocalAppdataLow, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sLowIntegrityTempBase) {
+    rv = GetLowIntegrityTempBase(getter_AddRefs(localFile));
+#endif
+  } else if (inAtom == nsDirectoryService::sPrinthood) {
+    rv = GetSpecialSystemDirectory(Win_Printhood, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sWinCookiesDirectory) {
+    rv = GetSpecialSystemDirectory(Win_Cookies, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sDefaultDownloadDirectory) {
+    rv = GetSpecialSystemDirectory(Win_Downloads, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sDocs) {
+    rv = GetSpecialSystemDirectory(Win_Documents, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sPictures) {
+    rv = GetSpecialSystemDirectory(Win_Pictures, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sMusic) {
+    rv = GetSpecialSystemDirectory(Win_Music, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sVideos) {
+    rv = GetSpecialSystemDirectory(Win_Videos, getter_AddRefs(localFile));
+  }
+#elif defined (XP_UNIX)
+
+  else if (inAtom == nsDirectoryService::sLocalDirectory) {
+    rv = GetSpecialSystemDirectory(Unix_LocalDirectory, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sLibDirectory) {
+    rv = GetSpecialSystemDirectory(Unix_LibDirectory, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sOS_HomeDirectory) {
+    rv = GetSpecialSystemDirectory(Unix_HomeDirectory, getter_AddRefs(localFile));
+  } else if (inAtom == nsDirectoryService::sXDGDesktop ||
+             inAtom == nsDirectoryService::sOS_DesktopDirectory) {
+    rv = GetSpecialSystemDirectory(Unix_XDG_Desktop, getter_AddRefs(localFile));
+    *aPersistent = false;
+  } else if (inAtom == nsDirectoryService::sXDGDocuments) {
+    rv = GetSpecialSystemDirectory(Unix_XDG_Documents, getter_AddRefs(localFile));
+    *aPersistent = false;
+  } else if (inAtom == nsDirectoryService::sXDGDownload ||
+             inAtom == nsDirectoryService::sDefaultDownloadDirectory) {
+    rv = GetSpecialSystemDirectory(Unix_XDG_Download, getter_AddRefs(localFile));
+    *aPersistent = false;
+  } else if (inAtom == nsDirectoryService::sXDGMusic) {
+    rv = GetSpecialSystemDirectory(Unix_XDG_Music, getter_AddRefs(localFile));
+    *aPersistent = false;
+  } else if (inAtom == nsDirectoryService::sXDGPictures) {
+    rv = GetSpecialSystemDirectory(Unix_XDG_Pictures, getter_AddRefs(localFile));
+    *aPersistent = false;
+  } else if (inAtom == nsDirectoryService::sXDGPublicShare) {
+    rv = GetSpecialSystemDirectory(Unix_XDG_PublicShare, getter_AddRefs(localFile));
+    *aPersistent = false;
+  } else if (inAtom == nsDirectoryService::sXDGTemplates) {
+    rv = GetSpecialSystemDirectory(Unix_XDG_Templates, getter_AddRefs(localFile));
+    *aPersistent = false;
+  } else if (inAtom == nsDirectoryService::sXDGVideos) {
+    rv = GetSpecialSystemDirectory(Unix_XDG_Videos, getter_AddRefs(localFile));
+    *aPersistent = false;
+  }
+#endif
+
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (!localFile) {
+    return NS_ERROR_FAILURE;
+  }
+
+  localFile.forget(aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDirectoryService::GetFiles(const char* aProp, nsISimpleEnumerator** aResult)
+{
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  *aResult = nullptr;
+
+  return NS_ERROR_FAILURE;
+}
diff --git a/xpcom/io/nsDirectoryService.h b/xpcom/io/nsDirectoryService.h
new file mode 100644
index 000000000..d0f92b75a
--- /dev/null
+++ b/xpcom/io/nsDirectoryService.h
@@ -0,0 +1,66 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsDirectoryService_h___
+#define nsDirectoryService_h___
+
+#include "nsIDirectoryService.h"
+#include "nsInterfaceHashtable.h"
+#include "nsIFile.h"
+#include "nsIAtom.h"
+#include "nsTArray.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/StaticPtr.h"
+
+#define NS_XPCOM_INIT_CURRENT_PROCESS_DIR       "MozBinD"   // Can be used to set NS_XPCOM_CURRENT_PROCESS_DIR
+                                                            // CANNOT be used to GET a location
+#define NS_DIRECTORY_SERVICE_CID  {0xf00152d0,0xb40b,0x11d3,{0x8c, 0x9c, 0x00, 0x00, 0x64, 0x65, 0x73, 0x74}}
+
+class nsDirectoryService final
+  : public nsIDirectoryService
+  , public nsIProperties
+  , public nsIDirectoryServiceProvider2
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  NS_DECL_NSIPROPERTIES
+
+  NS_DECL_NSIDIRECTORYSERVICE
+
+  NS_DECL_NSIDIRECTORYSERVICEPROVIDER
+
+  NS_DECL_NSIDIRECTORYSERVICEPROVIDER2
+
+  nsDirectoryService();
+
+  static void RealInit();
+  void RegisterCategoryProviders();
+
+  static nsresult
+  Create(nsISupports* aOuter, REFNSIID aIID, void** aResult);
+
+  static mozilla::StaticRefPtr<nsDirectoryService> gService;
+
+private:
+  ~nsDirectoryService();
+
+  nsresult GetCurrentProcessDirectory(nsIFile** aFile);
+
+  nsInterfaceHashtable<nsCStringHashKey, nsIFile> mHashtable;
+  nsTArray<nsCOMPtr<nsIDirectoryServiceProvider>> mProviders;
+
+public:
+
+#define DIR_ATOM(name_, value_) static nsIAtom* name_;
+#include "nsDirectoryServiceAtomList.h"
+#undef DIR_ATOM
+
+};
+
+
+#endif
+
diff --git a/xpcom/io/nsDirectoryServiceAtomList.h b/xpcom/io/nsDirectoryServiceAtomList.h
new file mode 100644
index 000000000..38a2f0e9d
--- /dev/null
+++ b/xpcom/io/nsDirectoryServiceAtomList.h
@@ -0,0 +1,98 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+DIR_ATOM(sCurrentProcess, NS_XPCOM_CURRENT_PROCESS_DIR)
+DIR_ATOM(sGRE_Directory, NS_GRE_DIR)
+DIR_ATOM(sGRE_BinDirectory, NS_GRE_BIN_DIR)
+DIR_ATOM(sOS_DriveDirectory, NS_OS_DRIVE_DIR)
+DIR_ATOM(sOS_TemporaryDirectory, NS_OS_TEMP_DIR)
+DIR_ATOM(sOS_CurrentProcessDirectory, NS_OS_CURRENT_PROCESS_DIR)
+DIR_ATOM(sOS_CurrentWorkingDirectory, NS_OS_CURRENT_WORKING_DIR)
+DIR_ATOM(sOS_HomeDirectory, NS_OS_HOME_DIR)
+DIR_ATOM(sOS_DesktopDirectory, NS_OS_DESKTOP_DIR)
+DIR_ATOM(sInitCurrentProcess_dummy, NS_XPCOM_INIT_CURRENT_PROCESS_DIR)
+#if defined (MOZ_WIDGET_COCOA)
+DIR_ATOM(sDirectory, NS_OS_SYSTEM_DIR)
+DIR_ATOM(sTrashDirectory, NS_MAC_TRASH_DIR)
+DIR_ATOM(sStartupDirectory, NS_MAC_STARTUP_DIR)
+DIR_ATOM(sShutdownDirectory, NS_MAC_SHUTDOWN_DIR)
+DIR_ATOM(sAppleMenuDirectory, NS_MAC_APPLE_MENU_DIR)
+DIR_ATOM(sControlPanelDirectory, NS_MAC_CONTROL_PANELS_DIR)
+DIR_ATOM(sExtensionDirectory, NS_MAC_EXTENSIONS_DIR)
+DIR_ATOM(sFontsDirectory, NS_MAC_FONTS_DIR)
+DIR_ATOM(sPreferencesDirectory, NS_MAC_PREFS_DIR)
+DIR_ATOM(sDocumentsDirectory, NS_MAC_DOCUMENTS_DIR)
+DIR_ATOM(sInternetSearchDirectory, NS_MAC_INTERNET_SEARCH_DIR)
+DIR_ATOM(sUserLibDirectory, NS_MAC_USER_LIB_DIR)
+DIR_ATOM(sDefaultDownloadDirectory, NS_OSX_DEFAULT_DOWNLOAD_DIR)
+DIR_ATOM(sUserDesktopDirectory, NS_OSX_USER_DESKTOP_DIR)
+DIR_ATOM(sLocalDesktopDirectory, NS_OSX_LOCAL_DESKTOP_DIR)
+DIR_ATOM(sUserApplicationsDirectory, NS_OSX_USER_APPLICATIONS_DIR)
+DIR_ATOM(sLocalApplicationsDirectory, NS_OSX_LOCAL_APPLICATIONS_DIR)
+DIR_ATOM(sUserDocumentsDirectory, NS_OSX_USER_DOCUMENTS_DIR)
+DIR_ATOM(sLocalDocumentsDirectory, NS_OSX_LOCAL_DOCUMENTS_DIR)
+DIR_ATOM(sUserInternetPlugInDirectory, NS_OSX_USER_INTERNET_PLUGIN_DIR)
+DIR_ATOM(sLocalInternetPlugInDirectory, NS_OSX_LOCAL_INTERNET_PLUGIN_DIR)
+DIR_ATOM(sUserFrameworksDirectory, NS_OSX_USER_FRAMEWORKS_DIR)
+DIR_ATOM(sLocalFrameworksDirectory, NS_OSX_LOCAL_FRAMEWORKS_DIR)
+DIR_ATOM(sUserPreferencesDirectory, NS_OSX_USER_PREFERENCES_DIR)
+DIR_ATOM(sLocalPreferencesDirectory, NS_OSX_LOCAL_PREFERENCES_DIR)
+DIR_ATOM(sPictureDocumentsDirectory, NS_OSX_PICTURE_DOCUMENTS_DIR)
+DIR_ATOM(sMovieDocumentsDirectory, NS_OSX_MOVIE_DOCUMENTS_DIR)
+DIR_ATOM(sMusicDocumentsDirectory, NS_OSX_MUSIC_DOCUMENTS_DIR)
+DIR_ATOM(sInternetSitesDirectory, NS_OSX_INTERNET_SITES_DIR)
+#elif defined (XP_WIN)
+DIR_ATOM(sSystemDirectory, NS_OS_SYSTEM_DIR)
+DIR_ATOM(sWindowsDirectory, NS_WIN_WINDOWS_DIR)
+DIR_ATOM(sWindowsProgramFiles, NS_WIN_PROGRAM_FILES_DIR)
+DIR_ATOM(sDesktop, NS_WIN_DESKTOP_DIR)
+DIR_ATOM(sPrograms, NS_WIN_PROGRAMS_DIR)
+DIR_ATOM(sControls, NS_WIN_CONTROLS_DIR)
+DIR_ATOM(sPrinters, NS_WIN_PRINTERS_DIR)
+DIR_ATOM(sPersonal, NS_WIN_PERSONAL_DIR)
+DIR_ATOM(sFavorites, NS_WIN_FAVORITES_DIR)
+DIR_ATOM(sStartup, NS_WIN_STARTUP_DIR)
+DIR_ATOM(sRecent, NS_WIN_RECENT_DIR)
+DIR_ATOM(sSendto, NS_WIN_SEND_TO_DIR)
+DIR_ATOM(sBitbucket, NS_WIN_BITBUCKET_DIR)
+DIR_ATOM(sStartmenu, NS_WIN_STARTMENU_DIR)
+DIR_ATOM(sDesktopdirectory, NS_WIN_DESKTOP_DIRECTORY)
+DIR_ATOM(sDrives, NS_WIN_DRIVES_DIR)
+DIR_ATOM(sNetwork, NS_WIN_NETWORK_DIR)
+DIR_ATOM(sNethood, NS_WIN_NETHOOD_DIR)
+DIR_ATOM(sFonts, NS_WIN_FONTS_DIR)
+DIR_ATOM(sTemplates, NS_WIN_TEMPLATES_DIR)
+DIR_ATOM(sCommon_Startmenu, NS_WIN_COMMON_STARTMENU_DIR)
+DIR_ATOM(sCommon_Programs, NS_WIN_COMMON_PROGRAMS_DIR)
+DIR_ATOM(sCommon_Startup, NS_WIN_COMMON_STARTUP_DIR)
+DIR_ATOM(sCommon_Desktopdirectory, NS_WIN_COMMON_DESKTOP_DIRECTORY)
+DIR_ATOM(sCommon_AppData, NS_WIN_COMMON_APPDATA_DIR)
+DIR_ATOM(sAppdata, NS_WIN_APPDATA_DIR)
+DIR_ATOM(sLocalAppdata, NS_WIN_LOCAL_APPDATA_DIR)
+#if defined(MOZ_CONTENT_SANDBOX)
+DIR_ATOM(sLocalAppdataLow, NS_WIN_LOCAL_APPDATA_LOW_DIR)
+DIR_ATOM(sLowIntegrityTempBase, NS_WIN_LOW_INTEGRITY_TEMP_BASE)
+#endif
+DIR_ATOM(sPrinthood, NS_WIN_PRINTHOOD)
+DIR_ATOM(sWinCookiesDirectory, NS_WIN_COOKIES_DIR)
+DIR_ATOM(sDefaultDownloadDirectory, NS_WIN_DEFAULT_DOWNLOAD_DIR)
+DIR_ATOM(sDocs, NS_WIN_DOCUMENTS_DIR)
+DIR_ATOM(sPictures, NS_WIN_PICTURES_DIR)
+DIR_ATOM(sMusic, NS_WIN_MUSIC_DIR)
+DIR_ATOM(sVideos, NS_WIN_VIDEOS_DIR)
+#elif defined (XP_UNIX)
+DIR_ATOM(sLocalDirectory, NS_UNIX_LOCAL_DIR)
+DIR_ATOM(sLibDirectory, NS_UNIX_LIB_DIR)
+DIR_ATOM(sDefaultDownloadDirectory, NS_UNIX_DEFAULT_DOWNLOAD_DIR)
+DIR_ATOM(sXDGDesktop, NS_UNIX_XDG_DESKTOP_DIR)
+DIR_ATOM(sXDGDocuments, NS_UNIX_XDG_DOCUMENTS_DIR)
+DIR_ATOM(sXDGDownload, NS_UNIX_XDG_DOWNLOAD_DIR)
+DIR_ATOM(sXDGMusic, NS_UNIX_XDG_MUSIC_DIR)
+DIR_ATOM(sXDGPictures, NS_UNIX_XDG_PICTURES_DIR)
+DIR_ATOM(sXDGPublicShare, NS_UNIX_XDG_PUBLIC_SHARE_DIR)
+DIR_ATOM(sXDGTemplates, NS_UNIX_XDG_TEMPLATES_DIR)
+DIR_ATOM(sXDGVideos, NS_UNIX_XDG_VIDEOS_DIR)
+#endif
diff --git a/xpcom/io/nsDirectoryServiceDefs.h b/xpcom/io/nsDirectoryServiceDefs.h
new file mode 100644
index 000000000..0bdc5e390
--- /dev/null
+++ b/xpcom/io/nsDirectoryServiceDefs.h
@@ -0,0 +1,168 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * Defines the property names for directories available from
+ * nsIDirectoryService. These dirs are always available even if no
+ * nsIDirectoryServiceProviders have been registered with the service.
+ * Application level keys are defined in nsAppDirectoryServiceDefs.h.
+ *
+ * Keys whose definition ends in "DIR" or "FILE" return a single nsIFile (or
+ * subclass). Keys whose definition ends in "LIST" return an nsISimpleEnumerator
+ * which enumerates a list of file objects.
+ *
+ * Defines listed in this file are FROZEN.  This list may grow.
+ */
+
+#ifndef nsDirectoryServiceDefs_h___
+#define nsDirectoryServiceDefs_h___
+
+/* General OS specific locations */
+
+#define NS_OS_HOME_DIR                          "Home"
+#define NS_OS_TEMP_DIR                          "TmpD"
+#define NS_OS_CURRENT_WORKING_DIR               "CurWorkD"
+/* Files stored in this directory will appear on the user's desktop,
+ * if there is one, otherwise it's just the same as "Home"
+ */
+#define NS_OS_DESKTOP_DIR                       "Desk"
+
+/* Property returns the directory in which the procces was started from.
+ * On Unix this will be the path in the MOZILLA_FIVE_HOME env var and if
+ * unset will be the current working directory.
+ */
+#define NS_OS_CURRENT_PROCESS_DIR               "CurProcD"
+
+/* This location is similar to NS_OS_CURRENT_PROCESS_DIR, however,
+ * NS_XPCOM_CURRENT_PROCESS_DIR can be overriden by passing a "bin
+ * directory" to NS_InitXPCOM2().
+ */
+#define NS_XPCOM_CURRENT_PROCESS_DIR            "XCurProcD"
+
+/* Property will return the location of the the XPCOM Shared Library.
+ */
+#define NS_XPCOM_LIBRARY_FILE                   "XpcomLib"
+
+/* Property will return the current location of the GRE directory.
+ * On OSX, this typically points to Contents/Resources in the app bundle.
+ * If no GRE is used, this propery will behave like
+ * NS_XPCOM_CURRENT_PROCESS_DIR.
+ */
+#define NS_GRE_DIR                              "GreD"
+
+/* Property will return the current location of the GRE-binaries directory.
+ * On OSX, this typically points to Contents/MacOS in the app bundle. On
+ * all other platforms, this will be identical to NS_GRE_DIR.
+ * Since this property is based on the NS_GRE_DIR, if no GRE is used, this
+ * propery will behave like NS_XPCOM_CURRENT_PROCESS_DIR.
+ */
+#define NS_GRE_BIN_DIR                          "GreBinD"
+
+/* Platform Specific Locations */
+
+#if !defined (XP_UNIX) || defined(MOZ_WIDGET_COCOA)
+    #define NS_OS_SYSTEM_DIR                    "SysD"
+#endif
+
+#if defined (MOZ_WIDGET_COCOA)
+  #define NS_MAC_DESKTOP_DIR                  NS_OS_DESKTOP_DIR
+  #define NS_MAC_TRASH_DIR                    "Trsh"
+  #define NS_MAC_STARTUP_DIR                  "Strt"
+  #define NS_MAC_SHUTDOWN_DIR                 "Shdwn"
+  #define NS_MAC_APPLE_MENU_DIR               "ApplMenu"
+  #define NS_MAC_CONTROL_PANELS_DIR           "CntlPnl"
+  #define NS_MAC_EXTENSIONS_DIR               "Exts"
+  #define NS_MAC_FONTS_DIR                    "Fnts"
+  #define NS_MAC_PREFS_DIR                    "Prfs"
+  #define NS_MAC_DOCUMENTS_DIR                "Docs"
+  #define NS_MAC_INTERNET_SEARCH_DIR          "ISrch"
+  #define NS_OSX_HOME_DIR                     NS_OS_HOME_DIR
+  #define NS_MAC_HOME_DIR                     NS_OS_HOME_DIR
+  #define NS_MAC_DEFAULT_DOWNLOAD_DIR         "DfltDwnld"
+  #define NS_MAC_USER_LIB_DIR                 "ULibDir"   // Only available under OS X
+  #define NS_OSX_DEFAULT_DOWNLOAD_DIR         NS_MAC_DEFAULT_DOWNLOAD_DIR
+  #define NS_OSX_USER_DESKTOP_DIR             "UsrDsk"
+  #define NS_OSX_LOCAL_DESKTOP_DIR            "LocDsk"
+  #define NS_OSX_USER_APPLICATIONS_DIR        "UsrApp"
+  #define NS_OSX_LOCAL_APPLICATIONS_DIR       "LocApp"
+  #define NS_OSX_USER_DOCUMENTS_DIR           "UsrDocs"
+  #define NS_OSX_LOCAL_DOCUMENTS_DIR          "LocDocs"
+  #define NS_OSX_USER_INTERNET_PLUGIN_DIR     "UsrIntrntPlgn"
+  #define NS_OSX_LOCAL_INTERNET_PLUGIN_DIR    "LoclIntrntPlgn"
+  #define NS_OSX_USER_FRAMEWORKS_DIR          "UsrFrmwrks"
+  #define NS_OSX_LOCAL_FRAMEWORKS_DIR         "LocFrmwrks"
+  #define NS_OSX_USER_PREFERENCES_DIR         "UsrPrfs"
+  #define NS_OSX_LOCAL_PREFERENCES_DIR        "LocPrfs"
+  #define NS_OSX_PICTURE_DOCUMENTS_DIR        "Pct"
+  #define NS_OSX_MOVIE_DOCUMENTS_DIR          "Mov"
+  #define NS_OSX_MUSIC_DOCUMENTS_DIR          "Music"
+  #define NS_OSX_INTERNET_SITES_DIR           "IntrntSts"
+#elif defined (XP_WIN)
+  #define NS_WIN_WINDOWS_DIR                  "WinD"
+  #define NS_WIN_PROGRAM_FILES_DIR            "ProgF"
+  #define NS_WIN_HOME_DIR                     NS_OS_HOME_DIR
+  #define NS_WIN_DESKTOP_DIR                  "DeskV" // virtual folder at the root of the namespace
+  #define NS_WIN_PROGRAMS_DIR                 "Progs" // User start menu programs directory!
+  #define NS_WIN_CONTROLS_DIR                 "Cntls"
+  #define NS_WIN_PRINTERS_DIR                 "Prnts"
+  #define NS_WIN_PERSONAL_DIR                 "Pers"
+  #define NS_WIN_FAVORITES_DIR                "Favs"
+  #define NS_WIN_STARTUP_DIR                  "Strt"
+  #define NS_WIN_RECENT_DIR                   "Rcnt"
+  #define NS_WIN_SEND_TO_DIR                  "SndTo"
+  #define NS_WIN_BITBUCKET_DIR                "Buckt"
+  #define NS_WIN_STARTMENU_DIR                "Strt"
+// This gives the same thing as NS_OS_DESKTOP_DIR
+  #define NS_WIN_DESKTOP_DIRECTORY            "DeskP" // file sys dir which physically stores objects on desktop
+  #define NS_WIN_DRIVES_DIR                   "Drivs"
+  #define NS_WIN_NETWORK_DIR                  "NetW"
+  #define NS_WIN_NETHOOD_DIR                  "netH"
+  #define NS_WIN_FONTS_DIR                    "Fnts"
+  #define NS_WIN_TEMPLATES_DIR                "Tmpls"
+  #define NS_WIN_COMMON_STARTMENU_DIR         "CmStrt"
+  #define NS_WIN_COMMON_PROGRAMS_DIR          "CmPrgs"
+  #define NS_WIN_COMMON_STARTUP_DIR           "CmStrt"
+  #define NS_WIN_COMMON_DESKTOP_DIRECTORY     "CmDeskP"
+  #define NS_WIN_COMMON_APPDATA_DIR           "CmAppData"
+  #define NS_WIN_APPDATA_DIR                  "AppData"
+  #define NS_WIN_LOCAL_APPDATA_DIR            "LocalAppData"
+#if defined(MOZ_CONTENT_SANDBOX)
+  #define NS_WIN_LOCAL_APPDATA_LOW_DIR        "LocalAppDataLow"
+  #define NS_WIN_LOW_INTEGRITY_TEMP_BASE      "LowTmpDBase"
+#endif
+  #define NS_WIN_PRINTHOOD                    "PrntHd"
+  #define NS_WIN_COOKIES_DIR                  "CookD"
+  #define NS_WIN_DEFAULT_DOWNLOAD_DIR         "DfltDwnld"
+  // On Win7 and up these ids will return the default save-to location for
+  // Windows Libraries associated with the specific content type. For other
+  // os they return the local user folder. Note these can return network file
+  // paths which can jank the ui thread so be careful how you access them.
+  #define NS_WIN_DOCUMENTS_DIR                "Docs"
+  #define NS_WIN_PICTURES_DIR                 "Pict"
+  #define NS_WIN_MUSIC_DIR                    "Music"
+  #define NS_WIN_VIDEOS_DIR                   "Vids"
+#elif defined (XP_UNIX)
+  #define NS_UNIX_LOCAL_DIR                   "Locl"
+  #define NS_UNIX_LIB_DIR                     "LibD"
+  #define NS_UNIX_HOME_DIR                    NS_OS_HOME_DIR
+  #define NS_UNIX_XDG_DESKTOP_DIR             "XDGDesk"
+  #define NS_UNIX_XDG_DOCUMENTS_DIR           "XDGDocs"
+  #define NS_UNIX_XDG_DOWNLOAD_DIR            "XDGDwnld"
+  #define NS_UNIX_XDG_MUSIC_DIR               "XDGMusic"
+  #define NS_UNIX_XDG_PICTURES_DIR            "XDGPict"
+  #define NS_UNIX_XDG_PUBLIC_SHARE_DIR        "XDGPubSh"
+  #define NS_UNIX_XDG_TEMPLATES_DIR           "XDGTempl"
+  #define NS_UNIX_XDG_VIDEOS_DIR              "XDGVids"
+  #define NS_UNIX_DEFAULT_DOWNLOAD_DIR        "DfltDwnld"
+#endif
+
+/* Deprecated */
+
+#define NS_OS_DRIVE_DIR                         "DrvD"
+
+
+
+#endif
diff --git a/xpcom/io/nsDirectoryServiceUtils.h b/xpcom/io/nsDirectoryServiceUtils.h
new file mode 100644
index 000000000..6100e7565
--- /dev/null
+++ b/xpcom/io/nsDirectoryServiceUtils.h
@@ -0,0 +1,31 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsDirectoryServiceUtils_h___
+#define nsDirectoryServiceUtils_h___
+
+#include "nsIServiceManager.h"
+#include "nsIProperties.h"
+#include "nsServiceManagerUtils.h"
+#include "nsCOMPtr.h"
+#include "nsXPCOMCID.h"
+#include "nsIFile.h"
+
+inline nsresult
+NS_GetSpecialDirectory(const char* aSpecialDirName, nsIFile** aResult)
+{
+  nsresult rv;
+  nsCOMPtr<nsIProperties> serv(do_GetService(NS_DIRECTORY_SERVICE_CONTRACTID,
+                                             &rv));
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  return serv->Get(aSpecialDirName, NS_GET_IID(nsIFile),
+                   reinterpret_cast<void**>(aResult));
+}
+
+#endif
diff --git a/xpcom/io/nsEscape.cpp b/xpcom/io/nsEscape.cpp
new file mode 100644
index 000000000..f16edc4ce
--- /dev/null
+++ b/xpcom/io/nsEscape.cpp
@@ -0,0 +1,633 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsEscape.h"
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/BinarySearch.h"
+#include "nsTArray.h"
+#include "nsCRT.h"
+#include "plstr.h"
+
+static const char hexCharsUpper[] = "0123456789ABCDEF";
+static const char hexCharsUpperLower[] = "0123456789ABCDEFabcdef";
+
+static const int netCharType[256] =
+/*  Bit 0       xalpha      -- the alphas
+**  Bit 1       xpalpha     -- as xalpha but
+**                             converts spaces to plus and plus to %2B
+**  Bit 3 ...   path        -- as xalphas but doesn't escape '/'
+*/
+  /* 0 1 2 3 4 5 6 7 8 9 A B C D E F */
+  {  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,   /* 0x */
+     0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,   /* 1x */
+     0,0,0,0,0,0,0,0,0,0,7,4,0,7,7,4,   /* 2x   !"#$%&'()*+,-./  */
+     7,7,7,7,7,7,7,7,7,7,0,0,0,0,0,0,   /* 3x  0123456789:;<=>?  */
+     0,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,   /* 4x  @ABCDEFGHIJKLMNO  */
+     /* bits for '@' changed from 7 to 0 so '@' can be escaped   */
+     /* in usernames and passwords in publishing.                */
+     7,7,7,7,7,7,7,7,7,7,7,0,0,0,0,7,   /* 5X  PQRSTUVWXYZ[\]^_  */
+     0,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,   /* 6x  `abcdefghijklmno  */
+     7,7,7,7,7,7,7,7,7,7,7,0,0,0,0,0,   /* 7X  pqrstuvwxyz{\}~  DEL */
+     0, };
+
+/* decode % escaped hex codes into character values
+ */
+#define UNHEX(C) \
+    ((C >= '0' && C <= '9') ? C - '0' : \
+     ((C >= 'A' && C <= 'F') ? C - 'A' + 10 : \
+     ((C >= 'a' && C <= 'f') ? C - 'a' + 10 : 0)))
+
+
+#define IS_OK(C) (netCharType[((unsigned int)(C))] & (aFlags))
+#define HEX_ESCAPE '%'
+
+static const uint32_t ENCODE_MAX_LEN = 6; // %uABCD
+
+static uint32_t
+AppendPercentHex(char* aBuffer, unsigned char aChar)
+{
+  uint32_t i = 0;
+  aBuffer[i++] = '%';
+  aBuffer[i++] = hexCharsUpper[aChar >> 4]; // high nibble
+  aBuffer[i++] = hexCharsUpper[aChar & 0xF]; // low nibble
+  return i;
+}
+
+static uint32_t
+AppendPercentHex(char16_t* aBuffer, char16_t aChar)
+{
+  uint32_t i = 0;
+  aBuffer[i++] = '%';
+  if (aChar & 0xff00) {
+    aBuffer[i++] = 'u';
+    aBuffer[i++] = hexCharsUpper[aChar >> 12]; // high-byte high nibble
+    aBuffer[i++] = hexCharsUpper[(aChar >> 8) & 0xF]; // high-byte low nibble
+  }
+  aBuffer[i++] = hexCharsUpper[(aChar >> 4) & 0xF]; // low-byte high nibble
+  aBuffer[i++] = hexCharsUpper[aChar & 0xF]; // low-byte low nibble
+  return i;
+}
+
+//----------------------------------------------------------------------------------------
+char*
+nsEscape(const char* aStr, size_t aLength, size_t* aOutputLength,
+         nsEscapeMask aFlags)
+//----------------------------------------------------------------------------------------
+{
+  if (!aStr) {
+    return nullptr;
+  }
+
+  size_t charsToEscape = 0;
+
+  const unsigned char* src = (const unsigned char*)aStr;
+  for (size_t i = 0; i < aLength; ++i) {
+    if (!IS_OK(src[i])) {
+      charsToEscape++;
+    }
+  }
+
+  // calculate how much memory should be allocated
+  // original length + 2 bytes for each escaped character + terminating '\0'
+  // do the sum in steps to check for overflow
+  size_t dstSize = aLength + 1 + charsToEscape;
+  if (dstSize <= aLength) {
+    return nullptr;
+  }
+  dstSize += charsToEscape;
+  if (dstSize < aLength) {
+    return nullptr;
+  }
+
+  // fail if we need more than 4GB
+  if (dstSize > UINT32_MAX) {
+    return nullptr;
+  }
+
+  char* result = (char*)moz_xmalloc(dstSize);
+  if (!result) {
+    return nullptr;
+  }
+
+  unsigned char* dst = (unsigned char*)result;
+  src = (const unsigned char*)aStr;
+  if (aFlags == url_XPAlphas) {
+    for (size_t i = 0; i < aLength; ++i) {
+      unsigned char c = *src++;
+      if (IS_OK(c)) {
+        *dst++ = c;
+      } else if (c == ' ') {
+        *dst++ = '+';  /* convert spaces to pluses */
+      } else {
+        *dst++ = HEX_ESCAPE;
+        *dst++ = hexCharsUpper[c >> 4];  /* high nibble */
+        *dst++ = hexCharsUpper[c & 0x0f];  /* low nibble */
+      }
+    }
+  } else {
+    for (size_t i = 0; i < aLength; ++i) {
+      unsigned char c = *src++;
+      if (IS_OK(c)) {
+        *dst++ = c;
+      } else {
+        *dst++ = HEX_ESCAPE;
+        *dst++ = hexCharsUpper[c >> 4];  /* high nibble */
+        *dst++ = hexCharsUpper[c & 0x0f];  /* low nibble */
+      }
+    }
+  }
+
+  *dst = '\0';     /* tack on eos */
+  if (aOutputLength) {
+    *aOutputLength = dst - (unsigned char*)result;
+  }
+
+  return result;
+}
+
+//----------------------------------------------------------------------------------------
+char*
+nsUnescape(char* aStr)
+//----------------------------------------------------------------------------------------
+{
+  nsUnescapeCount(aStr);
+  return aStr;
+}
+
+//----------------------------------------------------------------------------------------
+int32_t
+nsUnescapeCount(char* aStr)
+//----------------------------------------------------------------------------------------
+{
+  char* src = aStr;
+  char* dst = aStr;
+
+  char c1[] = " ";
+  char c2[] = " ";
+  char* const pc1 = c1;
+  char* const pc2 = c2;
+
+  if (!*src) {
+    // A null string was passed in.  Nothing to escape.
+    // Returns early as the string might not actually be mutable with
+    // length 0.
+    return 0;
+  }
+
+  while (*src) {
+    c1[0] = *(src + 1);
+    if (*(src + 1) == '\0') {
+      c2[0] = '\0';
+    } else {
+      c2[0] = *(src + 2);
+    }
+
+    if (*src != HEX_ESCAPE || PL_strpbrk(pc1, hexCharsUpperLower) == 0 ||
+        PL_strpbrk(pc2, hexCharsUpperLower) == 0) {
+      *dst++ = *src++;
+    } else {
+      src++; /* walk over escape */
+      if (*src) {
+        *dst = UNHEX(*src) << 4;
+        src++;
+      }
+      if (*src) {
+        *dst = (*dst + UNHEX(*src));
+        src++;
+      }
+      dst++;
+    }
+  }
+
+  *dst = 0;
+  return (int)(dst - aStr);
+
+} /* NET_UnEscapeCnt */
+
+
+char*
+nsEscapeHTML(const char* aString)
+{
+  char* rv = nullptr;
+  /* XXX Hardcoded max entity len. The +1 is for the trailing null. */
+  uint32_t len = strlen(aString);
+  if (len >= (UINT32_MAX / 6)) {
+    return nullptr;
+  }
+
+  rv = (char*)moz_xmalloc((6 * len) + 1);
+  char* ptr = rv;
+
+  if (rv) {
+    for (; *aString != '\0'; ++aString) {
+      if (*aString == '<') {
+        *ptr++ = '&';
+        *ptr++ = 'l';
+        *ptr++ = 't';
+        *ptr++ = ';';
+      } else if (*aString == '>') {
+        *ptr++ = '&';
+        *ptr++ = 'g';
+        *ptr++ = 't';
+        *ptr++ = ';';
+      } else if (*aString == '&') {
+        *ptr++ = '&';
+        *ptr++ = 'a';
+        *ptr++ = 'm';
+        *ptr++ = 'p';
+        *ptr++ = ';';
+      } else if (*aString == '"') {
+        *ptr++ = '&';
+        *ptr++ = 'q';
+        *ptr++ = 'u';
+        *ptr++ = 'o';
+        *ptr++ = 't';
+        *ptr++ = ';';
+      } else if (*aString == '\'') {
+        *ptr++ = '&';
+        *ptr++ = '#';
+        *ptr++ = '3';
+        *ptr++ = '9';
+        *ptr++ = ';';
+      } else {
+        *ptr++ = *aString;
+      }
+    }
+    *ptr = '\0';
+  }
+
+  return rv;
+}
+
+char16_t*
+nsEscapeHTML2(const char16_t* aSourceBuffer, int32_t aSourceBufferLen)
+{
+  // Calculate the length, if the caller didn't.
+  if (aSourceBufferLen < 0) {
+    aSourceBufferLen = NS_strlen(aSourceBuffer);
+  }
+
+  /* XXX Hardcoded max entity len. */
+  if (uint32_t(aSourceBufferLen) >=
+      ((UINT32_MAX - sizeof(char16_t)) / (6 * sizeof(char16_t)))) {
+    return nullptr;
+  }
+
+  char16_t* resultBuffer = (char16_t*)moz_xmalloc(
+    aSourceBufferLen * 6 * sizeof(char16_t) + sizeof(char16_t('\0')));
+  char16_t* ptr = resultBuffer;
+
+  if (resultBuffer) {
+    int32_t i;
+
+    for (i = 0; i < aSourceBufferLen; ++i) {
+      if (aSourceBuffer[i] == '<') {
+        *ptr++ = '&';
+        *ptr++ = 'l';
+        *ptr++ = 't';
+        *ptr++ = ';';
+      } else if (aSourceBuffer[i] == '>') {
+        *ptr++ = '&';
+        *ptr++ = 'g';
+        *ptr++ = 't';
+        *ptr++ = ';';
+      } else if (aSourceBuffer[i] == '&') {
+        *ptr++ = '&';
+        *ptr++ = 'a';
+        *ptr++ = 'm';
+        *ptr++ = 'p';
+        *ptr++ = ';';
+      } else if (aSourceBuffer[i] == '"') {
+        *ptr++ = '&';
+        *ptr++ = 'q';
+        *ptr++ = 'u';
+        *ptr++ = 'o';
+        *ptr++ = 't';
+        *ptr++ = ';';
+      } else if (aSourceBuffer[i] == '\'') {
+        *ptr++ = '&';
+        *ptr++ = '#';
+        *ptr++ = '3';
+        *ptr++ = '9';
+        *ptr++ = ';';
+      } else {
+        *ptr++ = aSourceBuffer[i];
+      }
+    }
+    *ptr = 0;
+  }
+
+  return resultBuffer;
+}
+
+//----------------------------------------------------------------------------------------
+//
+// The following table encodes which characters needs to be escaped for which
+// parts of an URL.  The bits are the "url components" in the enum EscapeMask,
+// see nsEscape.h.
+//
+// esc_Scheme        =     1
+// esc_Username      =     2
+// esc_Password      =     4
+// esc_Host          =     8
+// esc_Directory     =    16
+// esc_FileBaseName  =    32
+// esc_FileExtension =    64
+// esc_Param         =   128
+// esc_Query         =   256
+// esc_Ref           =   512
+
+static const uint32_t EscapeChars[256] =
+//   0    1    2    3    4    5    6    7    8    9    A    B    C    D    E    F
+{
+     0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,  // 0x
+     0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,  // 1x
+     0,1023,   0, 512,1023,   0,1023, 112,1023,1023,1023,1023,1023,1023, 953, 784,  // 2x   !"#$%&'()*+,-./
+  1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1008,1008,   0,1008,   0, 768,  // 3x  0123456789:;<=>?
+  1008,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,  // 4x  @ABCDEFGHIJKLMNO
+  1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1008, 896,1008, 896,1023,  // 5x  PQRSTUVWXYZ[\]^_
+   384,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,  // 6x  `abcdefghijklmno
+  1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023, 896,1012, 896,1023,   0,  // 7x  pqrstuvwxyz{|}~ DEL
+     0                                                                              // 80 to FF are zero
+};
+
+static uint16_t dontNeedEscape(unsigned char aChar, uint32_t aFlags)
+{
+  return EscapeChars[(uint32_t)aChar] & aFlags;
+}
+static uint16_t dontNeedEscape(uint16_t aChar, uint32_t aFlags)
+{
+  return aChar < mozilla::ArrayLength(EscapeChars) ?
+    (EscapeChars[(uint32_t)aChar]  & aFlags) : 0;
+}
+
+//----------------------------------------------------------------------------------------
+
+/**
+ * Templated helper for URL escaping a portion of a string.
+ *
+ * @param aPart The pointer to the beginning of the portion of the string to
+ *  escape.
+ * @param aPartLen The length of the string to escape.
+ * @param aFlags Flags used to configure escaping. @see EscapeMask
+ * @param aResult String that has the URL escaped portion appended to. Only
+ *  altered if the string is URL escaped or |esc_AlwaysCopy| is specified.
+ * @param aDidAppend Indicates whether or not data was appended to |aResult|.
+ * @return NS_ERROR_INVALID_ARG, NS_ERROR_OUT_OF_MEMORY on failure.
+ */
+template<class T>
+static nsresult
+T_EscapeURL(const typename T::char_type* aPart, size_t aPartLen,
+            uint32_t aFlags, T& aResult, bool& aDidAppend)
+{
+  typedef nsCharTraits<typename T::char_type> traits;
+  typedef typename traits::unsigned_char_type unsigned_char_type;
+  static_assert(sizeof(*aPart) == 1 || sizeof(*aPart) == 2,
+                "unexpected char type");
+
+  if (!aPart) {
+    NS_NOTREACHED("null pointer");
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  bool forced = !!(aFlags & esc_Forced);
+  bool ignoreNonAscii = !!(aFlags & esc_OnlyASCII);
+  bool ignoreAscii = !!(aFlags & esc_OnlyNonASCII);
+  bool writing = !!(aFlags & esc_AlwaysCopy);
+  bool colon = !!(aFlags & esc_Colon);
+
+  auto src = reinterpret_cast<const unsigned_char_type*>(aPart);
+
+  typename T::char_type tempBuffer[100];
+  unsigned int tempBufferPos = 0;
+
+  bool previousIsNonASCII = false;
+  for (size_t i = 0; i < aPartLen; ++i) {
+    unsigned_char_type c = *src++;
+
+    // if the char has not to be escaped or whatever follows % is
+    // a valid escaped string, just copy the char.
+    //
+    // Also the % will not be escaped until forced
+    // See bugzilla bug 61269 for details why we changed this
+    //
+    // And, we will not escape non-ascii characters if requested.
+    // On special request we will also escape the colon even when
+    // not covered by the matrix.
+    // ignoreAscii is not honored for control characters (C0 and DEL)
+    //
+    // And, we should escape the '|' character when it occurs after any
+    // non-ASCII character as it may be aPart of a multi-byte character.
+    //
+    // 0x20..0x7e are the valid ASCII characters. We also escape spaces
+    // (0x20) since they are not legal in URLs.
+    if ((dontNeedEscape(c, aFlags) || (c == HEX_ESCAPE && !forced)
+         || (c > 0x7f && ignoreNonAscii)
+         || (c > 0x20 && c < 0x7f && ignoreAscii))
+        && !(c == ':' && colon)
+        && !(previousIsNonASCII && c == '|' && !ignoreNonAscii)) {
+      if (writing) {
+        tempBuffer[tempBufferPos++] = c;
+      }
+    } else { /* do the escape magic */
+      if (!writing) {
+        if (!aResult.Append(aPart, i, fallible)) {
+          return NS_ERROR_OUT_OF_MEMORY;
+        }
+        writing = true;
+      }
+      uint32_t len = ::AppendPercentHex(tempBuffer + tempBufferPos, c);
+      tempBufferPos += len;
+      MOZ_ASSERT(len <= ENCODE_MAX_LEN, "potential buffer overflow");
+    }
+
+    // Flush the temp buffer if it doesnt't have room for another encoded char.
+    if (tempBufferPos >= mozilla::ArrayLength(tempBuffer) - ENCODE_MAX_LEN) {
+      NS_ASSERTION(writing, "should be writing");
+      if (!aResult.Append(tempBuffer, tempBufferPos, fallible)) {
+        return NS_ERROR_OUT_OF_MEMORY;
+      }
+      tempBufferPos = 0;
+    }
+
+    previousIsNonASCII = (c > 0x7f);
+  }
+  if (writing) {
+    if (!aResult.Append(tempBuffer, tempBufferPos, fallible)) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+  }
+  aDidAppend = writing;
+  return NS_OK;
+}
+
+bool
+NS_EscapeURL(const char* aPart, int32_t aPartLen, uint32_t aFlags,
+             nsACString& aResult)
+{
+  if (aPartLen < 0) {
+    aPartLen = strlen(aPart);
+  }
+
+  bool result = false;
+  nsresult rv = T_EscapeURL(aPart, aPartLen, aFlags, aResult, result);
+  if (NS_FAILED(rv)) {
+    ::NS_ABORT_OOM(aResult.Length() * sizeof(nsACString::char_type));
+  }
+
+  return result;
+}
+
+nsresult
+NS_EscapeURL(const nsCSubstring& aStr, uint32_t aFlags, nsCSubstring& aResult,
+             const mozilla::fallible_t&)
+{
+  bool appended = false;
+  nsresult rv = T_EscapeURL(aStr.Data(), aStr.Length(), aFlags, aResult, appended);
+  if (NS_FAILED(rv)) {
+    aResult.Truncate();
+    return rv;
+  }
+
+  if (!appended) {
+    aResult = aStr;
+  }
+
+  return rv;
+}
+
+const nsSubstring&
+NS_EscapeURL(const nsSubstring& aStr, uint32_t aFlags, nsSubstring& aResult)
+{
+  bool result = false;
+  nsresult rv = T_EscapeURL<nsSubstring>(aStr.Data(), aStr.Length(), aFlags, aResult, result);
+
+  if (NS_FAILED(rv)) {
+    ::NS_ABORT_OOM(aResult.Length() * sizeof(nsSubstring::char_type));
+  }
+
+  if (result) {
+    return aResult;
+  }
+  return aStr;
+}
+
+// Starting at aStr[aStart] find the first index in aStr that matches any
+// character in aForbidden. Return false if not found.
+static bool
+FindFirstMatchFrom(const nsAFlatString& aStr, size_t aStart,
+                   const nsTArray<char16_t>& aForbidden, size_t* aIndex)
+{
+  const size_t len = aForbidden.Length();
+  for (size_t j = aStart, l = aStr.Length(); j < l; ++j) {
+    size_t unused;
+    if (mozilla::BinarySearch(aForbidden, 0, len, aStr[j], &unused)) {
+      *aIndex = j;
+      return true;
+    }
+  }
+  return false;
+}
+
+const nsSubstring&
+NS_EscapeURL(const nsAFlatString& aStr, const nsTArray<char16_t>& aForbidden,
+             nsSubstring& aResult)
+{
+  bool didEscape = false;
+  for (size_t i = 0, strLen = aStr.Length(); i < strLen; ) {
+    size_t j;
+    if (MOZ_UNLIKELY(FindFirstMatchFrom(aStr, i, aForbidden, &j))) {
+      if (i == 0) {
+        didEscape = true;
+        aResult.Truncate();
+        aResult.SetCapacity(aStr.Length());
+      }
+      if (j != i) {
+        // The substring from 'i' up to 'j' that needs no escaping.
+        aResult.Append(nsDependentSubstring(aStr, i, j - i));
+      }
+      char16_t buffer[ENCODE_MAX_LEN];
+      uint32_t bufferLen = ::AppendPercentHex(buffer, aStr[j]);
+      MOZ_ASSERT(bufferLen <= ENCODE_MAX_LEN, "buffer overflow");
+      aResult.Append(buffer, bufferLen);
+      i = j + 1;
+    } else {
+      if (MOZ_UNLIKELY(didEscape)) {
+        // The tail of the string that needs no escaping.
+        aResult.Append(nsDependentSubstring(aStr, i, strLen - i));
+      }
+      break;
+    }
+  }
+  if (MOZ_UNLIKELY(didEscape)) {
+    return aResult;
+  }
+  return aStr;
+}
+
+#define ISHEX(c) memchr(hexCharsUpperLower, c, sizeof(hexCharsUpperLower)-1)
+
+bool
+NS_UnescapeURL(const char* aStr, int32_t aLen, uint32_t aFlags,
+               nsACString& aResult)
+{
+  if (!aStr) {
+    NS_NOTREACHED("null pointer");
+    return false;
+  }
+
+  MOZ_ASSERT(aResult.IsEmpty(),
+             "Passing a non-empty string as an out parameter!");
+
+  if (aLen < 0) {
+    aLen = strlen(aStr);
+  }
+
+  bool ignoreNonAscii = !!(aFlags & esc_OnlyASCII);
+  bool ignoreAscii = !!(aFlags & esc_OnlyNonASCII);
+  bool writing = !!(aFlags & esc_AlwaysCopy);
+  bool skipControl = !!(aFlags & esc_SkipControl);
+  bool skipInvalidHostChar = !!(aFlags & esc_Host);
+
+  if (writing) {
+    aResult.SetCapacity(aLen);
+  }
+
+  const char* last = aStr;
+  const char* p = aStr;
+
+  for (int i = 0; i < aLen; ++i, ++p) {
+    if (*p == HEX_ESCAPE && i < aLen - 2) {
+      unsigned char c1 = *((unsigned char*)p + 1);
+      unsigned char c2 = *((unsigned char*)p + 2);
+      unsigned char u = (UNHEX(c1) << 4) + UNHEX(c2);
+      if (ISHEX(c1) && ISHEX(c2) &&
+          (!skipInvalidHostChar || dontNeedEscape(u, aFlags) || c1 >= '8') &&
+          ((c1 < '8' && !ignoreAscii) || (c1 >= '8' && !ignoreNonAscii)) &&
+          !(skipControl &&
+            (c1 < '2' || (c1 == '7' && (c2 == 'f' || c2 == 'F'))))) {
+        if (!writing) {
+          writing = true;
+          aResult.SetCapacity(aLen);
+        }
+        if (p > last) {
+          aResult.Append(last, p - last);
+          last = p;
+        }
+        aResult.Append(u);
+        i += 2;
+        p += 2;
+        last += 3;
+      }
+    }
+  }
+  if (writing && last < aStr + aLen) {
+    aResult.Append(last, aStr + aLen - last);
+  }
+
+  return writing;
+}
diff --git a/xpcom/io/nsEscape.h b/xpcom/io/nsEscape.h
new file mode 100644
index 000000000..bf89b737a
--- /dev/null
+++ b/xpcom/io/nsEscape.h
@@ -0,0 +1,224 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*	First checked in on 98/12/03 by John R. McMullen, derived from net.h/mkparse.c. */
+
+#ifndef _ESCAPE_H_
+#define _ESCAPE_H_
+
+#include "nscore.h"
+#include "nsError.h"
+#include "nsString.h"
+
+/**
+ * Valid mask values for nsEscape
+ * Note: these values are copied in nsINetUtil.idl. Any changes should be kept
+ * in sync.
+ */
+typedef enum {
+  url_All       = 0,       // %-escape every byte unconditionally
+  url_XAlphas   = 1u << 0, // Normal escape - leave alphas intact, escape the rest
+  url_XPAlphas  = 1u << 1, // As url_XAlphas, but convert spaces (0x20) to '+' and plus to %2B
+  url_Path      = 1u << 2  // As url_XAlphas, but don't escape slash ('/')
+} nsEscapeMask;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Escape the given string according to mask
+ * @param aSstr The string to escape
+ * @param aLength The length of the string to escape
+ * @param aOutputLen A pointer that will be used to store the length of the
+ *        output string, if not null
+ * @param aMask How to escape the string
+ * @return A newly allocated escaped string that must be free'd with
+ *         nsCRT::free, or null on failure
+ * @note: Please, don't use this function. Use NS_Escape instead!
+ */
+char* nsEscape(const char* aStr, size_t aLength, size_t* aOutputLen,
+               nsEscapeMask aMask);
+
+char* nsUnescape(char* aStr);
+/* decode % escaped hex codes into character values,
+ * modifies the parameter, returns the same buffer
+ */
+
+int32_t nsUnescapeCount(char* aStr);
+/* decode % escaped hex codes into character values,
+ * modifies the parameter buffer, returns the length of the result
+ * (result may contain \0's).
+ */
+
+char*
+nsEscapeHTML(const char* aString);
+
+char16_t*
+nsEscapeHTML2(const char16_t* aSourceBuffer,
+              int32_t aSourceBufferLen = -1);
+/*
+ * Escape problem char's for HTML display
+ */
+
+
+#ifdef __cplusplus
+}
+#endif
+
+
+/**
+ * NS_EscapeURL/NS_UnescapeURL constants for |flags| parameter:
+ *
+ * Note: These values are copied to nsINetUtil.idl
+ *       Any changes should be kept in sync
+ */
+enum EscapeMask {
+  /** url components **/
+  esc_Scheme         = 1u << 0,
+  esc_Username       = 1u << 1,
+  esc_Password       = 1u << 2,
+  esc_Host           = 1u << 3,
+  esc_Directory      = 1u << 4,
+  esc_FileBaseName   = 1u << 5,
+  esc_FileExtension  = 1u << 6,
+  esc_FilePath       = esc_Directory | esc_FileBaseName | esc_FileExtension,
+  esc_Param          = 1u << 7,
+  esc_Query          = 1u << 8,
+  esc_Ref            = 1u << 9,
+  /** special flags **/
+  esc_Minimal        = esc_Scheme | esc_Username | esc_Password | esc_Host | esc_FilePath | esc_Param | esc_Query | esc_Ref,
+  esc_Forced         = 1u << 10, /* forces escaping of existing escape sequences */
+  esc_OnlyASCII      = 1u << 11, /* causes non-ascii octets to be skipped */
+  esc_OnlyNonASCII   = 1u << 12, /* causes _graphic_ ascii octets (0x20-0x7E)
+                                    * to be skipped when escaping. causes all
+                                    * ascii octets (<= 0x7F) to be skipped when unescaping */
+  esc_AlwaysCopy     = 1u << 13, /* copy input to result buf even if escaping is unnecessary */
+  esc_Colon          = 1u << 14, /* forces escape of colon */
+  esc_SkipControl    = 1u << 15  /* skips C0 and DEL from unescaping */
+};
+
+/**
+ * NS_EscapeURL
+ *
+ * Escapes invalid char's in an URL segment.  Has no side-effect if the URL
+ * segment is already escaped, unless aFlags has the esc_Forced bit in which
+ * case % will also be escaped.  Iff some part of aStr is escaped is the
+ * final result appended to aResult.  You can also request that aStr is
+ * always appended to aResult with esc_AlwaysCopy.
+ *
+ * @param aStr     url segment string
+ * @param aLen     url segment string length (-1 if unknown)
+ * @param aFlags   url segment type flag (see EscapeMask above)
+ * @param aResult  result buffer, untouched if aStr is already escaped unless
+ *                 aFlags has esc_AlwaysCopy
+ *
+ * @return true if aResult was written to (i.e. at least one character was
+ *              escaped or esc_AlwaysCopy was requested), false otherwise.
+ */
+bool NS_EscapeURL(const char* aStr,
+                  int32_t aLen,
+                  uint32_t aFlags,
+                  nsACString& aResult);
+
+/**
+ * Expands URL escape sequences... beware embedded null bytes!
+ *
+ * @param aStr     url string to unescape
+ * @param aLen     length of aStr
+ * @param aFlags   only esc_OnlyNonASCII, esc_SkipControl and esc_AlwaysCopy
+ *                 are recognized
+ * @param aResult  result buffer, untouched if aStr is already unescaped unless
+ *                 aFlags has esc_AlwaysCopy
+ *
+ * @return true if aResult was written to (i.e. at least one character was
+ *              unescaped or esc_AlwaysCopy was requested), false otherwise.
+ */
+bool NS_UnescapeURL(const char* aStr,
+                    int32_t aLen,
+                    uint32_t aFlags,
+                    nsACString& aResult);
+
+/** returns resultant string length **/
+inline int32_t
+NS_UnescapeURL(char* aStr)
+{
+  return nsUnescapeCount(aStr);
+}
+
+/**
+ * String friendly versions...
+ */
+inline const nsCSubstring&
+NS_EscapeURL(const nsCSubstring& aStr, uint32_t aFlags, nsCSubstring& aResult)
+{
+  if (NS_EscapeURL(aStr.Data(), aStr.Length(), aFlags, aResult)) {
+    return aResult;
+  }
+  return aStr;
+}
+
+/**
+ * Fallible version of NS_EscapeURL. On success aResult will point to either
+ * the original string or an escaped copy.
+ */
+nsresult
+NS_EscapeURL(const nsCSubstring& aStr, uint32_t aFlags, nsCSubstring& aResult,
+             const mozilla::fallible_t&);
+
+inline const nsCSubstring&
+NS_UnescapeURL(const nsCSubstring& aStr, uint32_t aFlags, nsCSubstring& aResult)
+{
+  if (NS_UnescapeURL(aStr.Data(), aStr.Length(), aFlags, aResult)) {
+    return aResult;
+  }
+  return aStr;
+}
+const nsSubstring&
+NS_EscapeURL(const nsSubstring& aStr, uint32_t aFlags, nsSubstring& aResult);
+
+/**
+ * Percent-escapes all characters in aStr that occurs in aForbidden.
+ * @param aStr the input URL string
+ * @param aForbidden the characters that should be escaped if found in aStr
+ * @note that aForbidden MUST be sorted (low to high)
+ * @param aResult the result if some characters were escaped
+ * @return aResult if some characters were escaped, or aStr otherwise (aResult
+ *         is unmodified in that case)
+ */
+const nsSubstring&
+NS_EscapeURL(const nsAFlatString& aStr, const nsTArray<char16_t>& aForbidden,
+             nsSubstring& aResult);
+
+/**
+ * CString version of nsEscape. Returns true on success, false
+ * on out of memory. To reverse this function, use NS_UnescapeURL.
+ */
+inline bool
+NS_Escape(const nsACString& aOriginal, nsACString& aEscaped,
+          nsEscapeMask aMask)
+{
+  size_t escLen = 0;
+  char* esc = nsEscape(aOriginal.BeginReading(), aOriginal.Length(), &escLen,
+                       aMask);
+  if (! esc) {
+    return false;
+  }
+  aEscaped.Adopt(esc, escLen);
+  return true;
+}
+
+/**
+ * Inline unescape of mutable string object.
+ */
+inline nsACString&
+NS_UnescapeURL(nsACString& aStr)
+{
+  aStr.SetLength(nsUnescapeCount(aStr.BeginWriting()));
+  return aStr;
+}
+
+#endif //  _ESCAPE_H_
diff --git a/xpcom/io/nsIAsyncInputStream.idl b/xpcom/io/nsIAsyncInputStream.idl
new file mode 100644
index 000000000..5570817dd
--- /dev/null
+++ b/xpcom/io/nsIAsyncInputStream.idl
@@ -0,0 +1,104 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIInputStream.idl"
+
+interface nsIInputStreamCallback;
+interface nsIEventTarget;
+
+/**
+ * If an input stream is non-blocking, it may return NS_BASE_STREAM_WOULD_BLOCK
+ * when read.  The caller must then wait for the stream to have some data to 
+ * read.  If the stream implements nsIAsyncInputStream, then the caller can use 
+ * this interface to request an asynchronous notification when the stream
+ * becomes readable or closed (via the AsyncWait method).
+ *
+ * While this interface is almost exclusively used with non-blocking streams, it
+ * is not necessary that nsIInputStream::isNonBlocking return true.  Nor is it
+ * necessary that a non-blocking nsIInputStream implementation also implement
+ * nsIAsyncInputStream.
+ */
+[scriptable, uuid(a5f255ab-4801-4161-8816-277ac92f6ad1)]
+interface nsIAsyncInputStream : nsIInputStream
+{
+    /**
+     * This method closes the stream and sets its internal status.  If the 
+     * stream is already closed, then this method is ignored.  Once the stream
+     * is closed, the stream's status cannot be changed.  Any successful status
+     * code passed to this method is treated as NS_BASE_STREAM_CLOSED, which
+     * has an effect equivalent to nsIInputStream::close. 
+     *
+     * NOTE: this method exists in part to support pipes, which have both an 
+     * input end and an output end.  If the input end of a pipe is closed, then
+     * writes to the output end of the pipe will fail.  The error code returned 
+     * when an attempt is made to write to a "broken" pipe corresponds to the
+     * status code passed in when the input end of the pipe was closed, which
+     * greatly simplifies working with pipes in some cases.
+     *
+     * @param aStatus
+     *        The error that will be reported if this stream is accessed after
+     *        it has been closed.
+     */
+    void closeWithStatus(in nsresult aStatus);
+
+    /**
+     * Asynchronously wait for the stream to be readable or closed.  The
+     * notification is one-shot, meaning that each asyncWait call will result
+     * in exactly one notification callback.  After the OnInputStreamReady event
+     * is dispatched, the stream releases its reference to the 
+     * nsIInputStreamCallback object.  It is safe to call asyncWait again from the
+     * notification handler.
+     *
+     * This method may be called at any time (even if read has not been called).
+     * In other words, this method may be called when the stream already has
+     * data to read.  It may also be called when the stream is closed.  If the
+     * stream is already readable or closed when AsyncWait is called, then the
+     * OnInputStreamReady event will be dispatched immediately.  Otherwise, the
+     * event will be dispatched when the stream becomes readable or closed.
+     * 
+     * @param aCallback
+     *        This object is notified when the stream becomes ready.  This
+     *        parameter may be null to clear an existing callback.
+     * @param aFlags
+     *        This parameter specifies optional flags passed in to configure
+     *        the behavior of this method.  Pass zero to specify no flags.
+     * @param aRequestedCount
+     *        Wait until at least this many bytes can be read.  This is only
+     *        a suggestion to the underlying stream; it may be ignored.  The
+     *        caller may pass zero to indicate no preference.
+     * @param aEventTarget
+     *        Specify NULL to receive notification on ANY thread (possibly even
+     *        recursively on the calling thread -- i.e., synchronously), or
+     *        specify that the notification be delivered to a specific event
+     *        target.
+     */
+    void asyncWait(in nsIInputStreamCallback aCallback,
+                   in unsigned long aFlags,
+                   in unsigned long aRequestedCount,
+                   in nsIEventTarget aEventTarget);
+
+    /**
+     * If passed to asyncWait, this flag overrides the default behavior,
+     * causing the OnInputStreamReady notification to be suppressed until the
+     * stream becomes closed (either as a result of closeWithStatus/close being
+     * called on the stream or possibly due to some error in the underlying
+     * stream).
+     */
+    const unsigned long WAIT_CLOSURE_ONLY = (1<<0);
+};
+
+/**
+ * This is a companion interface for nsIAsyncInputStream::asyncWait.
+ */
+[function, scriptable, uuid(d1f28e94-3a6e-4050-a5f5-2e81b1fc2a43)]
+interface nsIInputStreamCallback : nsISupports
+{
+    /**
+     * Called to indicate that the stream is either readable or closed.
+     *
+     * @param aStream
+     *        The stream whose asyncWait method was called.
+     */
+    void onInputStreamReady(in nsIAsyncInputStream aStream);
+};
diff --git a/xpcom/io/nsIAsyncOutputStream.idl b/xpcom/io/nsIAsyncOutputStream.idl
new file mode 100644
index 000000000..7e74579c6
--- /dev/null
+++ b/xpcom/io/nsIAsyncOutputStream.idl
@@ -0,0 +1,104 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIOutputStream.idl"
+
+interface nsIOutputStreamCallback;
+interface nsIEventTarget;
+
+/**
+ * If an output stream is non-blocking, it may return NS_BASE_STREAM_WOULD_BLOCK
+ * when written to.  The caller must then wait for the stream to become
+ * writable.  If the stream implements nsIAsyncOutputStream, then the caller can
+ * use this interface to request an asynchronous notification when the stream
+ * becomes writable or closed (via the AsyncWait method).
+ *
+ * While this interface is almost exclusively used with non-blocking streams, it
+ * is not necessary that nsIOutputStream::isNonBlocking return true.  Nor is it
+ * necessary that a non-blocking nsIOutputStream implementation also implement
+ * nsIAsyncOutputStream.
+ */
+[scriptable, uuid(beb632d3-d77a-4e90-9134-f9ece69e8200)]
+interface nsIAsyncOutputStream : nsIOutputStream
+{
+    /**
+     * This method closes the stream and sets its internal status.  If the 
+     * stream is already closed, then this method is ignored.  Once the stream
+     * is closed, the stream's status cannot be changed.  Any successful status
+     * code passed to this method is treated as NS_BASE_STREAM_CLOSED, which
+     * is equivalent to nsIInputStream::close. 
+     *
+     * NOTE: this method exists in part to support pipes, which have both an 
+     * input end and an output end.  If the output end of a pipe is closed, then
+     * reads from the input end of the pipe will fail.  The error code returned 
+     * when an attempt is made to read from a "closed" pipe corresponds to the
+     * status code passed in when the output end of the pipe is closed, which
+     * greatly simplifies working with pipes in some cases.
+     *
+     * @param aStatus
+     *        The error that will be reported if this stream is accessed after
+     *        it has been closed.
+     */
+    void closeWithStatus(in nsresult reason);
+
+    /**
+     * Asynchronously wait for the stream to be writable or closed.  The
+     * notification is one-shot, meaning that each asyncWait call will result
+     * in exactly one notification callback.  After the OnOutputStreamReady event
+     * is dispatched, the stream releases its reference to the 
+     * nsIOutputStreamCallback object.  It is safe to call asyncWait again from the
+     * notification handler.
+     *
+     * This method may be called at any time (even if write has not been called).
+     * In other words, this method may be called when the stream already has
+     * room for more data.  It may also be called when the stream is closed.  If
+     * the stream is already writable or closed when AsyncWait is called, then the
+     * OnOutputStreamReady event will be dispatched immediately.  Otherwise, the
+     * event will be dispatched when the stream becomes writable or closed.
+     * 
+     * @param aCallback
+     *        This object is notified when the stream becomes ready.  This
+     *        parameter may be null to clear an existing callback.
+     * @param aFlags
+     *        This parameter specifies optional flags passed in to configure
+     *        the behavior of this method.  Pass zero to specify no flags.
+     * @param aRequestedCount
+     *        Wait until at least this many bytes can be written.  This is only
+     *        a suggestion to the underlying stream; it may be ignored.  The
+     *        caller may pass zero to indicate no preference.
+     * @param aEventTarget
+     *        Specify NULL to receive notification on ANY thread (possibly even
+     *        recursively on the calling thread -- i.e., synchronously), or
+     *        specify that the notification be delivered to a specific event
+     *        target.
+     */
+    void asyncWait(in nsIOutputStreamCallback aCallback,
+                   in unsigned long aFlags,
+                   in unsigned long aRequestedCount,
+                   in nsIEventTarget aEventTarget);
+
+    /**
+     * If passed to asyncWait, this flag overrides the default behavior,
+     * causing the OnOutputStreamReady notification to be suppressed until the
+     * stream becomes closed (either as a result of closeWithStatus/close being
+     * called on the stream or possibly due to some error in the underlying
+     * stream).
+     */
+    const unsigned long WAIT_CLOSURE_ONLY = (1<<0);
+};
+
+/**
+ * This is a companion interface for nsIAsyncOutputStream::asyncWait.
+ */
+[function, scriptable, uuid(40dbcdff-9053-42c5-a57c-3ec910d0f148)]
+interface nsIOutputStreamCallback : nsISupports
+{
+    /**
+     * Called to indicate that the stream is either writable or closed.
+     *
+     * @param aStream
+     *        The stream whose asyncWait method was called.
+     */
+    void onOutputStreamReady(in nsIAsyncOutputStream aStream);
+};
diff --git a/xpcom/io/nsIBinaryInputStream.idl b/xpcom/io/nsIBinaryInputStream.idl
new file mode 100644
index 000000000..c3a27e203
--- /dev/null
+++ b/xpcom/io/nsIBinaryInputStream.idl
@@ -0,0 +1,119 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIInputStream.idl"
+
+/**
+ * This interface allows consumption of primitive data types from a "binary
+ * stream" containing untagged, big-endian binary data, i.e. as produced by an
+ * implementation of nsIBinaryOutputStream.  This might be used, for example,
+ * to implement network protocols or to read from architecture-neutral disk
+ * files, i.e. ones that can be read and written by both big-endian and
+ * little-endian platforms.
+ *
+ * @See nsIBinaryOutputStream
+ */
+
+[scriptable, uuid(899b826b-2eb3-469c-8b31-4c29f5d341a6)]
+interface nsIBinaryInputStream : nsIInputStream {
+    void setInputStream(in nsIInputStream aInputStream);
+    
+    /**
+     * Read 8-bits from the stream.
+     *
+     * @return that byte to be treated as a boolean.
+     */
+    boolean readBoolean();
+
+    uint8_t read8();
+    uint16_t read16();
+    uint32_t read32();
+    uint64_t read64();
+
+    float readFloat();
+    double readDouble();
+
+    /**
+     * Read an 8-bit pascal style string from the stream.
+     * 32-bit length field, followed by length 8-bit chars.
+     */
+    ACString readCString();
+
+    /**
+     * Read an 16-bit pascal style string from the stream.
+     * 32-bit length field, followed by length PRUnichars.
+     */
+    AString readString();
+
+    /**
+     * Read an opaque byte array from the stream.
+     *
+     * @param aLength the number of bytes that must be read.
+     *
+     * @throws NS_ERROR_FAILURE if it can't read aLength bytes
+     */
+    void readBytes(in uint32_t aLength,
+                   [size_is(aLength), retval] out string aString);
+
+    /**
+     * Read an opaque byte array from the stream, storing the results
+     * as an array of PRUint8s.
+     *
+     * @param aLength the number of bytes that must be read.
+     *
+     * @throws NS_ERROR_FAILURE if it can't read aLength bytes
+     */
+    void readByteArray(in uint32_t aLength,
+                       [array, size_is(aLength), retval] out uint8_t aBytes);
+
+    /**
+     * Read opaque bytes from the stream, storing the results in an ArrayBuffer.
+     *
+     * @param aLength the number of bytes that must be read
+     * @param aArrayBuffer the arraybuffer in which to store the results
+     * Note: passing view.buffer, where view is an ArrayBufferView of an
+     *       ArrayBuffer, is not valid unless view.byteOffset == 0.
+     *
+     * @return The number of bytes actually read into aArrayBuffer.
+     */
+    [implicit_jscontext]
+    unsigned long readArrayBuffer(in uint32_t aLength, in jsval aArrayBuffer);
+};
+
+%{C++
+
+#ifdef MOZILLA_INTERNAL_API
+#include "nsString.h"
+
+inline nsresult
+NS_ReadOptionalCString(nsIBinaryInputStream* aStream, nsACString& aResult)
+{
+    bool nonnull;
+    nsresult rv = aStream->ReadBoolean(&nonnull);
+    if (NS_SUCCEEDED(rv)) {
+        if (nonnull)
+            rv = aStream->ReadCString(aResult);
+        else
+            aResult.Truncate();
+    }
+    return rv;
+}
+
+inline nsresult
+NS_ReadOptionalString(nsIBinaryInputStream* aStream, nsAString& aResult)
+{
+    bool nonnull;
+    nsresult rv = aStream->ReadBoolean(&nonnull);
+    if (NS_SUCCEEDED(rv)) {
+        if (nonnull)
+            rv = aStream->ReadString(aResult);
+        else
+            aResult.Truncate();
+    }
+    return rv;
+}
+#endif
+
+%}
diff --git a/xpcom/io/nsIBinaryOutputStream.idl b/xpcom/io/nsIBinaryOutputStream.idl
new file mode 100644
index 000000000..4d426d580
--- /dev/null
+++ b/xpcom/io/nsIBinaryOutputStream.idl
@@ -0,0 +1,90 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIOutputStream.idl"
+
+/**
+ * This interface allows writing of primitive data types (integers,
+ * floating-point values, booleans, etc.) to a stream in a binary, untagged,
+ * fixed-endianness format.  This might be used, for example, to implement
+ * network protocols or to produce architecture-neutral binary disk files,
+ * i.e. ones that can be read and written by both big-endian and little-endian
+ * platforms.  Output is written in big-endian order (high-order byte first),
+ * as this is traditional network order.
+ *
+ * @See nsIBinaryInputStream
+ */
+
+[scriptable, uuid(204ee610-8765-11d3-90cf-0040056a906e)]
+interface nsIBinaryOutputStream : nsIOutputStream {
+    void setOutputStream(in nsIOutputStream aOutputStream);
+    
+    /**
+     * Write a boolean as an 8-bit char to the stream.
+     */
+    void writeBoolean(in boolean aBoolean);
+
+    void write8(in uint8_t aByte);
+    void write16(in uint16_t a16);
+    void write32(in uint32_t a32);
+    void write64(in uint64_t a64);
+
+    void writeFloat(in float aFloat);
+    void writeDouble(in double aDouble);
+
+    /**
+     * Write an 8-bit pascal style string to the stream.
+     * 32-bit length field, followed by length 8-bit chars.
+     */
+    void writeStringZ(in string aString);
+
+    /**
+     * Write a 16-bit pascal style string to the stream.
+     * 32-bit length field, followed by length PRUnichars.
+     */
+    void writeWStringZ(in wstring aString);
+
+    /**
+     * Write an 8-bit pascal style string (UTF8-encoded) to the stream.
+     * 32-bit length field, followed by length 8-bit chars.
+     */
+    void writeUtf8Z(in wstring aString);
+
+    /**
+     * Write an opaque byte array to the stream.
+     */
+    void writeBytes([size_is(aLength)] in string aString, in uint32_t aLength);
+
+    /**
+     * Write an opaque byte array to the stream.
+     */
+    void writeByteArray([array, size_is(aLength)] in uint8_t aBytes,
+                        in uint32_t aLength);
+
+};
+
+%{C++
+
+inline nsresult
+NS_WriteOptionalStringZ(nsIBinaryOutputStream* aStream, const char* aString)
+{
+    bool nonnull = (aString != nullptr);
+    nsresult rv = aStream->WriteBoolean(nonnull);
+    if (NS_SUCCEEDED(rv) && nonnull)
+        rv = aStream->WriteStringZ(aString);
+    return rv;
+}
+
+inline nsresult
+NS_WriteOptionalWStringZ(nsIBinaryOutputStream* aStream, const char16_t* aString)
+{
+    bool nonnull = (aString != nullptr);
+    nsresult rv = aStream->WriteBoolean(nonnull);
+    if (NS_SUCCEEDED(rv) && nonnull)
+        rv = aStream->WriteWStringZ(aString);
+    return rv;
+}
+
+%}
diff --git a/xpcom/io/nsICloneableInputStream.idl b/xpcom/io/nsICloneableInputStream.idl
new file mode 100644
index 000000000..4fd9a74f7
--- /dev/null
+++ b/xpcom/io/nsICloneableInputStream.idl
@@ -0,0 +1,22 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIInputStream.idl"
+
+[scriptable, builtinclass, uuid(8149be1f-44d3-4f14-8b65-a57a5fbbeb97)]
+interface nsICloneableInputStream : nsISupports
+{
+  // Allow streams that implement the interface to determine if cloning
+  // possible at runtime.  For example, this allows wrappers to check if
+  // their base stream supports cloning.
+  [infallible] readonly attribute boolean cloneable;
+
+  // Produce a copy of the current stream in the most efficient way possible.
+  // In this case "copy" means that both the original and cloned streams
+  // should produce the same bytes for all future reads.  Bytes that have
+  // already been consumed from the original stream are not copied to the
+  // clone.  Operations on the two streams should be completely independent
+  // after the clone() occurs.
+  nsIInputStream clone();
+};
diff --git a/xpcom/io/nsIConverterInputStream.idl b/xpcom/io/nsIConverterInputStream.idl
new file mode 100644
index 000000000..7f35d8c5c
--- /dev/null
+++ b/xpcom/io/nsIConverterInputStream.idl
@@ -0,0 +1,40 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIUnicharInputStream.idl"
+
+interface nsIInputStream;
+
+/**
+ * A unichar input stream that wraps an input stream.
+ * This allows reading unicode strings from a stream, automatically converting
+ * the bytes from a selected character encoding.
+ */
+[scriptable, uuid(FC66FFB6-5404-4908-A4A3-27F92FA0579D)]
+interface nsIConverterInputStream : nsIUnicharInputStream {
+    /**
+     * Default replacement char value, U+FFFD REPLACEMENT CHARACTER.
+     */
+    const char16_t DEFAULT_REPLACEMENT_CHARACTER = 0xFFFD;
+
+    /**
+     * Initialize this stream.
+     * @param aStream 
+     *        The underlying stream to read from.
+     * @param aCharset
+     *        The character encoding to use for converting the bytes of the
+     *        stream. A null charset will be interpreted as UTF-8.
+     * @param aBufferSize
+     *        How many bytes to buffer.
+     * @param aReplacementChar
+     *        The character to replace unknown byte sequences in the stream
+     *        with. The standard replacement character is U+FFFD.
+     *        A value of 0x0000 will cause an exception to be thrown if unknown
+     *        byte sequences are encountered in the stream.
+     */
+    void init (in nsIInputStream aStream, in string aCharset,
+               in long aBufferSize, in char16_t aReplacementChar);
+};
+
diff --git a/xpcom/io/nsIConverterOutputStream.idl b/xpcom/io/nsIConverterOutputStream.idl
new file mode 100644
index 000000000..a93d3cfa6
--- /dev/null
+++ b/xpcom/io/nsIConverterOutputStream.idl
@@ -0,0 +1,44 @@
+/* vim:set expandtab ts=4 sw=4 sts=4 cin: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIUnicharOutputStream.idl"
+
+interface nsIOutputStream;
+
+/**
+ * This interface allows writing strings to a stream, doing automatic
+ * character encoding conversion.
+ */
+[scriptable, uuid(4b71113a-cb0d-479f-8ed5-01daeba2e8d4)]
+interface nsIConverterOutputStream : nsIUnicharOutputStream
+{
+    /**
+     * Initialize this stream. Must be called before any other method on this
+     * interface, or you will crash. The output stream passed to this method
+     * must not be null, or you will crash.
+     *
+     * @param aOutStream
+     *        The underlying output stream to which the converted strings will
+     *        be written.
+     * @param aCharset
+     *        The character set to use for encoding the characters. A null
+     *        charset will be interpreted as UTF-8.
+     * @param aBufferSize
+     *        How many bytes to buffer. A value of 0 means that no bytes will be
+     *        buffered. Implementations not supporting buffering may ignore
+     *        this parameter.
+     * @param aReplacementCharacter
+     *        The replacement character to use when an unsupported character is found.
+     *        The character must be encodable in the selected character
+     *        encoding; otherwise, attempts to write an unsupported character
+     *        will throw NS_ERROR_LOSS_OF_SIGNIFICANT_DATA.
+     *
+     *        A value of 0x0000 will cause an exception to be thrown upon
+     *        attempts to write unsupported characters.
+     */
+    void init(in nsIOutputStream aOutStream, in string aCharset,
+              in unsigned long aBufferSize,
+              in char16_t aReplacementCharacter);
+};
diff --git a/xpcom/io/nsIDirectoryEnumerator.idl b/xpcom/io/nsIDirectoryEnumerator.idl
new file mode 100644
index 000000000..7a1135fda
--- /dev/null
+++ b/xpcom/io/nsIDirectoryEnumerator.idl
@@ -0,0 +1,34 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ 
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIFile;
+
+/**
+ * This interface provides a means for enumerating the contents of a directory.
+ * It is similar to nsISimpleEnumerator except the retrieved entries are QI'ed 
+ * to nsIFile, and there is a mechanism for closing the directory when the 
+ * enumeration is complete.
+ */
+[scriptable, uuid(31f7f4ae-6916-4f2d-a81e-926a4e3022ee)]
+interface nsIDirectoryEnumerator : nsISupports
+{
+  /**
+   * Retrieves the next file in the sequence. The "nextFile" element is the 
+   * first element upon the first call. This attribute is null if there is no 
+   * next element.
+   */
+  readonly attribute nsIFile nextFile;
+
+  /**
+   * Closes the directory being enumerated, releasing the system resource.
+   * @throws NS_OK if the call succeeded and the directory was closed.
+   *         NS_ERROR_FAILURE if the directory close failed. 
+   *         It is safe to call this function many times. 
+   */
+  void close();
+};
+
diff --git a/xpcom/io/nsIDirectoryService.idl b/xpcom/io/nsIDirectoryService.idl
new file mode 100644
index 000000000..6f58e37b9
--- /dev/null
+++ b/xpcom/io/nsIDirectoryService.idl
@@ -0,0 +1,103 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIFile;
+interface nsISimpleEnumerator;
+
+/**
+ * nsIDirectoryServiceProvider
+ *
+ * Used by Directory Service to get file locations.
+ */
+
+[scriptable, uuid(bbf8cab0-d43a-11d3-8cc2-00609792278c)]
+interface nsIDirectoryServiceProvider: nsISupports
+{
+ /**
+  * getFile
+  *
+  * Directory Service calls this when it gets the first request for
+  * a prop or on every request if the prop is not persistent.
+  *
+  * @param prop         The symbolic name of the file.
+  * @param persistent   TRUE - The returned file will be cached by Directory
+  *                     Service. Subsequent requests for this prop will
+  *                     bypass the provider and use the cache.
+  *                     FALSE - The provider will be asked for this prop
+  *                     each time it is requested.
+  *
+  * @return             The file represented by the property.
+  *
+  */ 
+  nsIFile getFile(in string prop, out boolean persistent);
+};
+
+/**
+ * nsIDirectoryServiceProvider2
+ *
+ * An extension of nsIDirectoryServiceProvider which allows
+ * multiple files to be returned for the given key.
+ */
+
+[scriptable, uuid(2f977d4b-5485-11d4-87e2-0010a4e75ef2)]
+interface nsIDirectoryServiceProvider2: nsIDirectoryServiceProvider
+{
+ /**
+  * getFiles
+  *
+  * Directory Service calls this when it gets a request for
+  * a prop and the requested type is nsISimpleEnumerator.
+  *
+  * @param prop         The symbolic name of the file list.
+  *
+  * @return             An enumerator for a list of file locations.
+  *                     The elements in the enumeration are nsIFile
+  * @returnCode         NS_SUCCESS_AGGREGATE_RESULT if this result should be
+  *                     aggregated with other "lower" providers.
+  */
+  nsISimpleEnumerator getFiles(in string prop);
+};
+
+/**
+ * nsIDirectoryService
+ */
+
+[scriptable, uuid(57a66a60-d43a-11d3-8cc2-00609792278c)]
+interface nsIDirectoryService: nsISupports
+{
+ /**
+  * init
+  *
+  * Must be called. Used internally by XPCOM initialization.
+  *
+  */
+  void init();
+
+ /**
+  * registerProvider
+  *
+  * Register a provider with the service.
+  *
+  * @param prov            The service will keep a strong reference
+  *                        to this object. It will be released when
+  *                        the service is released.
+  *
+  */  
+  void registerProvider(in nsIDirectoryServiceProvider prov);
+  
+ /**
+  * unregisterProvider
+  *
+  * Unregister a provider with the service.
+  *
+  * @param prov            
+  *
+  */  
+  void unregisterProvider(in nsIDirectoryServiceProvider prov);
+};
+
+
diff --git a/xpcom/io/nsIFile.idl b/xpcom/io/nsIFile.idl
new file mode 100644
index 000000000..fc07106b9
--- /dev/null
+++ b/xpcom/io/nsIFile.idl
@@ -0,0 +1,521 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+%{C++
+struct PRFileDesc;
+struct PRLibrary;
+#include <stdio.h>
+%}
+
+[ptr] native PRFileDescStar(PRFileDesc);
+[ptr] native PRLibraryStar(PRLibrary);
+[ptr] native FILE(FILE);
+
+interface nsISimpleEnumerator;
+
+/**
+ * An nsIFile is an abstract representation of a filename. It manages
+ * filename encoding issues, pathname component separators ('/' vs. '\\'
+ * vs. ':') and weird stuff like differing volumes with identical names, as
+ * on pre-Darwin Macintoshes.
+ *
+ * This file has long introduced itself to new hackers with this opening
+ * paragraph:
+ *
+ *    This is the only correct cross-platform way to specify a file.
+ *    Strings are not such a way. If you grew up on windows or unix, you
+ *    may think they are.  Welcome to reality.
+ *
+ * While taking the pose struck here to heart would be uncalled for, one
+ * may safely conclude that writing cross-platform code is an embittering
+ * experience.
+ *
+ * All methods with string parameters have two forms.  The preferred
+ * form operates on UCS-2 encoded characters strings.  An alternate
+ * form operates on characters strings encoded in the "native" charset.
+ *
+ * A string containing characters encoded in the native charset cannot
+ * be safely passed to javascript via xpconnect.  Therefore, the "native
+ * methods" are not scriptable.
+ */
+[scriptable, main_process_scriptable_only, uuid(2fa6884a-ae65-412a-9d4c-ce6e34544ba1), builtinclass]
+interface nsIFile : nsISupports
+{
+    /**
+     *  Create Types
+     *
+     *  NORMAL_FILE_TYPE - A normal file.
+     *  DIRECTORY_TYPE   - A directory/folder.
+     */
+    const unsigned long NORMAL_FILE_TYPE = 0;
+    const unsigned long DIRECTORY_TYPE   = 1;
+
+    /**
+     *  append[Native]
+     *
+     *  This function is used for constructing a descendent of the
+     *  current nsIFile.
+     *
+     *   @param node
+     *       A string which is intended to be a child node of the nsIFile.
+     *       For the |appendNative| method, the node must be in the native
+     *       filesystem charset.
+     */
+    void append(in AString node);
+    [noscript] void appendNative(in ACString node);
+
+    /**
+     *  Normalize the pathName (e.g. removing .. and . components on Unix).
+     */
+    void normalize();
+
+    /**
+     *  create
+     *
+     *  This function will create a new file or directory in the
+     *  file system. Any nodes that have not been created or
+     *  resolved, will be.  If the file or directory already
+     *  exists create() will return NS_ERROR_FILE_ALREADY_EXISTS.
+     *
+     *   @param type
+     *       This specifies the type of file system object
+     *       to be made.  The only two types at this time
+     *       are file and directory which are defined above.
+     *       If the type is unrecongnized, we will return an
+     *       error (NS_ERROR_FILE_UNKNOWN_TYPE).
+     *
+     *   @param permissions
+     *       The unix style octal permissions.  This may
+     *       be ignored on systems that do not need to do
+     *       permissions.
+     */
+    [must_use] void create(in unsigned long type, in unsigned long permissions);
+
+    /**
+     *  Accessor to the leaf name of the file itself.      
+     *  For the |nativeLeafName| method, the nativeLeafName must 
+     *  be in the native filesystem charset.
+     */
+    attribute AString leafName;
+    [noscript] attribute ACString nativeLeafName;
+
+    /**
+     *  copyTo[Native]
+     *
+     *  This will copy this file to the specified newParentDir.
+     *  If a newName is specified, the file will be renamed.
+     *  If 'this' is not created we will return an error
+     *  (NS_ERROR_FILE_TARGET_DOES_NOT_EXIST).
+     *
+     *  copyTo may fail if the file already exists in the destination 
+     *  directory.
+     *
+     *  copyTo will NOT resolve aliases/shortcuts during the copy.
+     *
+     *   @param newParentDir
+     *       This param is the destination directory. If the
+     *       newParentDir is null, copyTo() will use the parent
+     *       directory of this file. If the newParentDir is not
+     *       empty and is not a directory, an error will be
+     *       returned (NS_ERROR_FILE_DESTINATION_NOT_DIR). For the 
+     *       |CopyToNative| method, the newName must be in the 
+     *       native filesystem charset.
+     *
+     *   @param newName
+     *       This param allows you to specify a new name for
+     *       the file to be copied. This param may be empty, in
+     *       which case the current leaf name will be used.
+     */
+    void copyTo(in nsIFile newParentDir, in AString newName);
+    [noscript] void CopyToNative(in nsIFile newParentDir, in ACString newName);
+
+    /**
+     *  copyToFollowingLinks[Native]
+     *
+     *  This function is identical to copyTo with the exception that,
+     *  as the name implies, it follows symbolic links.  The XP_UNIX
+     *  implementation always follow symbolic links when copying.  For 
+     *  the |CopyToFollowingLinks| method, the newName must be in the 
+     *  native filesystem charset.
+     */
+    void copyToFollowingLinks(in nsIFile newParentDir, in AString newName);
+    [noscript] void copyToFollowingLinksNative(in nsIFile newParentDir, in ACString newName);
+
+    /**
+     *  moveTo[Native]
+     *
+     *  A method to move this file or directory to newParentDir.
+     *  If a newName is specified, the file or directory will be renamed.
+     *  If 'this' is not created we will return an error
+     *  (NS_ERROR_FILE_TARGET_DOES_NOT_EXIST).
+     *  If 'this' is a file, and the destination file already exists, moveTo
+     *  will replace the old file.
+     *  This object is updated to refer to the new file.
+     *
+     *  moveTo will NOT resolve aliases/shortcuts during the copy.
+     *  moveTo will do the right thing and allow copies across volumes.
+     *  moveTo will return an error (NS_ERROR_FILE_DIR_NOT_EMPTY) if 'this' is
+     *  a directory and the destination directory is not empty.
+     *  moveTo will return an error (NS_ERROR_FILE_ACCESS_DENIED) if 'this' is
+     *  a directory and the destination directory is not writable.
+     *
+     *   @param newParentDir
+     *       This param is the destination directory. If the
+     *       newParentDir is empty, moveTo() will rename the file
+     *       within its current directory. If the newParentDir is
+     *       not empty and does not name a directory, an error will
+     *       be returned (NS_ERROR_FILE_DESTINATION_NOT_DIR).  For 
+     *       the |moveToNative| method, the newName must be in the 
+     *       native filesystem charset.
+     *
+     *   @param newName
+     *       This param allows you to specify a new name for
+     *       the file to be moved. This param may be empty, in
+     *       which case the current leaf name will be used.
+     */
+    void moveTo(in nsIFile newParentDir, in AString newName);
+    [noscript] void moveToNative(in nsIFile newParentDir, in ACString newName);
+
+    /**
+     *  renameTo
+     *
+     *  This method is identical to moveTo except that if this file or directory
+     *  is moved to a a different volume, it fails and returns an error
+     *  (NS_ERROR_FILE_ACCESS_DENIED).
+     *  This object will still point to the old location after renaming.
+     */
+    void renameTo(in nsIFile newParentDir, in AString newName);
+    [noscript] void renameToNative(in nsIFile newParentDir, in ACString newName);
+
+    /**
+     *  This will try to delete this file.  The 'recursive' flag
+     *  must be PR_TRUE to delete directories which are not empty.
+     *
+     *  This will not resolve any symlinks.
+     */
+    void remove(in boolean recursive);
+
+    /**
+     *  Attributes of nsIFile.
+     */
+
+    attribute unsigned long permissions;
+    attribute unsigned long permissionsOfLink;
+
+    /**
+     *  File Times are to be in milliseconds from
+     *  midnight (00:00:00), January 1, 1970 Greenwich Mean
+     *  Time (GMT).
+     */
+    attribute PRTime lastModifiedTime;
+    attribute PRTime lastModifiedTimeOfLink;
+
+    /**
+     *  WARNING!  On the Mac, getting/setting the file size with nsIFile
+     *  only deals with the size of the data fork.  If you need to
+     *  know the size of the combined data and resource forks use the
+     *  GetFileSizeWithResFork() method defined on nsILocalFileMac.
+     */
+    attribute int64_t fileSize;
+    readonly attribute int64_t fileSizeOfLink;
+
+    /**
+     *  target & path
+     *
+     *  Accessor to the string path.  The native version of these
+     *  strings are not guaranteed to be a usable path to pass to
+     *  NSPR or the C stdlib.  There are problems that affect
+     *  platforms on which a path does not fully specify a file
+     *  because two volumes can have the same name (e.g., mac).
+     *  This is solved by holding "private", native data in the
+     *  nsIFile implementation.  This native data is lost when
+     *  you convert to a string.
+     *
+     *      DO NOT PASS TO USE WITH NSPR OR STDLIB!
+     *
+     *  target
+     *      Find out what the symlink points at.  Will give error
+     *      (NS_ERROR_FILE_INVALID_PATH) if not a symlink.
+     *
+     *  path
+     *      Find out what the nsIFile points at.
+     *
+     *  Note that the ACString attributes are returned in the 
+     *  native filesystem charset.
+     *
+     */
+    readonly attribute AString target;
+    [noscript] readonly attribute ACString nativeTarget;
+    readonly attribute AString path;
+    [noscript] readonly attribute ACString nativePath;
+
+    boolean exists();
+    boolean isWritable();
+    boolean isReadable();
+    boolean isExecutable();
+    boolean isHidden();
+    boolean isDirectory();
+    boolean isFile();
+    boolean isSymlink();
+    /**
+     * Not a regular file, not a directory, not a symlink.
+     */
+    boolean isSpecial();
+
+    /**
+     *  createUnique
+     *  
+     *  This function will create a new file or directory in the
+     *  file system. Any nodes that have not been created or
+     *  resolved, will be.  If this file already exists, we try
+     *  variations on the leaf name "suggestedName" until we find
+     *  one that did not already exist.
+     *
+     *  If the search for nonexistent files takes too long
+     *  (thousands of the variants already exist), we give up and
+     *  return NS_ERROR_FILE_TOO_BIG.
+     *
+     *   @param type
+     *       This specifies the type of file system object
+     *       to be made.  The only two types at this time
+     *       are file and directory which are defined above.
+     *       If the type is unrecongnized, we will return an
+     *       error (NS_ERROR_FILE_UNKNOWN_TYPE).
+     *
+     *   @param permissions
+     *       The unix style octal permissions.  This may
+     *       be ignored on systems that do not need to do
+     *       permissions.
+     */
+    [must_use]
+    void createUnique(in unsigned long type, in unsigned long permissions);
+
+    /**
+      * clone()
+      *
+      * This function will allocate and initialize a nsIFile object to the
+      * exact location of the |this| nsIFile.
+      *
+      *   @param file
+      *          A nsIFile which this object will be initialize
+      *          with.
+      *
+      */
+    nsIFile clone();
+
+    /**
+     *  Will determine if the inFile equals this.
+     */
+    boolean equals(in nsIFile inFile);
+
+    /**
+     *  Will determine if inFile is a descendant of this file.
+     *  This routine looks in subdirectories too.
+     */
+    boolean contains(in nsIFile inFile);
+
+    /**
+     *  Parent will be null when this is at the top of the volume.
+     */
+    readonly attribute nsIFile parent;
+    
+    /**
+     *  Returns an enumeration of the elements in a directory. Each
+     *  element in the enumeration is an nsIFile.
+     *
+     *   @throws NS_ERROR_FILE_NOT_DIRECTORY if the current nsIFile does
+     *           not specify a directory.
+     */
+    readonly attribute nsISimpleEnumerator directoryEntries;
+
+    /**
+     *  initWith[Native]Path
+     *
+     *  This function will initialize the nsIFile object.  Any
+     *  internal state information will be reset.
+     *
+     *   @param filePath       
+     *       A string which specifies a full file path to a 
+     *       location.  Relative paths will be treated as an
+     *       error (NS_ERROR_FILE_UNRECOGNIZED_PATH).  For 
+     *       initWithNativePath, the filePath must be in the native
+     *       filesystem charset.
+     */
+    void initWithPath(in AString filePath);
+    [noscript] void initWithNativePath(in ACString filePath);
+    
+    /**
+     *  initWithFile
+     *
+     *  Initialize this object with another file
+     *
+     *   @param aFile
+     *       the file this becomes equivalent to
+     */
+    void initWithFile(in nsIFile aFile);
+    
+    /**
+     *  followLinks
+     *
+     *  This attribute will determine if the nsLocalFile will auto
+     *  resolve symbolic links.  By default, this value will be false
+     *  on all non unix systems.  On unix, this attribute is effectively
+     *  a noop.  
+     */
+    attribute boolean followLinks;  
+
+    /**
+     * Flag for openNSPRFileDesc(), to hint to the OS that the file will be
+     * read sequentially with agressive readahead.
+     */
+    const unsigned long OS_READAHEAD = 0x40000000;
+    
+    /**
+     * Flag for openNSPRFileDesc(). Deprecated and unreliable!
+     * Instead use NS_OpenAnonymousTemporaryFile() to create a temporary
+     * file which will be deleted upon close!
+     */
+    const unsigned long DELETE_ON_CLOSE = 0x80000000;
+
+    /**
+     * Return the result of PR_Open on the file.  The caller is
+     * responsible for calling PR_Close on the result.  On success, the
+     * returned PRFileDescr must be non-null.
+     *
+     * @param flags the PR_Open flags from prio.h, plus optionally
+     * OS_READAHEAD or DELETE_ON_CLOSE. OS_READAHEAD is a hint to the
+     * OS that the file will be read sequentially with agressive
+     * readahead. DELETE_ON_CLOSE is unreliable on Windows and is deprecated.
+     * Instead use NS_OpenAnonymousTemporaryFile() to create a temporary
+     * file which will be deleted upon close.
+     */
+    [noscript, must_use] PRFileDescStar openNSPRFileDesc(in long flags,
+                                                         in long mode);
+
+    /**
+     * Return the result of fopen on the file.  The caller is
+     * responsible for calling fclose on the result.  On success, the
+     * returned FILE pointer must be non-null.
+     */
+    [noscript, must_use] FILE openANSIFileDesc(in string mode);
+
+    /**
+     * Return the result of PR_LoadLibrary on the file.  The caller is
+     * responsible for calling PR_UnloadLibrary on the result.
+     */
+    [noscript, must_use] PRLibraryStar  load();
+
+    // number of bytes available on disk to non-superuser
+    [must_use] readonly attribute int64_t diskSpaceAvailable;
+
+    /**
+     *  appendRelative[Native]Path
+     *
+     *  Append a relative path to the current path of the nsIFile object.
+     *
+     *   @param relativeFilePath
+     *       relativeFilePath is a native relative path. For security reasons,
+     *       this cannot contain .. or cannot start with a directory separator.
+     *       For the |appendRelativeNativePath| method, the relativeFilePath 
+     *       must be in the native filesystem charset.
+     */
+    void appendRelativePath(in AString relativeFilePath);
+    [noscript] void appendRelativeNativePath(in ACString relativeFilePath);
+    
+    /**
+     *  Accessor to a null terminated string which will specify
+     *  the file in a persistent manner for disk storage.
+     *
+     *  The character set of this attribute is undefined.  DO NOT TRY TO
+     *  INTERPRET IT AS HUMAN READABLE TEXT!
+     */
+    [must_use] attribute ACString persistentDescriptor;
+
+    /**
+     *  reveal
+     *
+     *  Ask the operating system to open the folder which contains
+     *  this file or folder. This routine only works on platforms which
+     *  support the ability to open a folder and is run async on Windows.
+     *  This routine must be called on the main.
+     */
+    [must_use] void reveal();
+
+    /**
+     *  launch
+     *
+     *  Ask the operating system to attempt to open the file.
+     *  this really just simulates "double clicking" the file on your platform.
+     *  This routine only works on platforms which support this functionality
+     *  and is run async on Windows.  This routine must be called on the
+     *  main thread.
+     */
+    [must_use] void launch();
+
+    /**
+     *  getRelativeDescriptor
+     *
+     *  Returns a relative file path in an opaque, XP format. It is therefore
+     *  not a native path.
+     *
+     *  The character set of the string returned from this function is
+     *  undefined.  DO NOT TRY TO INTERPRET IT AS HUMAN READABLE TEXT!
+     *
+     *   @param fromFile
+     *       the file from which the descriptor is relative.
+     *       Throws if fromFile is null.
+     */
+    [must_use] ACString getRelativeDescriptor(in nsIFile fromFile);
+
+    /**
+     *  setRelativeDescriptor
+     *
+     *  Initializes the file to the location relative to fromFile using
+     *  a string returned by getRelativeDescriptor.
+     *
+     *   @param fromFile
+     *       the file to which the descriptor is relative
+     *   @param relative
+     *       the relative descriptor obtained from getRelativeDescriptor
+     */
+    [must_use]
+    void setRelativeDescriptor(in nsIFile fromFile, in ACString relativeDesc);
+
+    /**
+     *  getRelativePath
+     *
+     *  Returns a relative file from 'fromFile' to this file as a UTF-8 string.
+     *  Going up the directory tree is represented via "../".  '/' is used as
+     *  the path segment separator.  This is not a native path, since it's UTF-8
+     *  encoded.
+     *
+     *   @param fromFile
+     *       the file from which the path is relative.
+     *       Throws if fromFile is null.
+     */
+    [must_use] AUTF8String getRelativePath(in nsIFile fromFile);
+
+    /**
+     *  setRelativePath
+     *
+     *  Initializes the file to the location relative to fromFile using
+     *  a string returned by getRelativePath.
+     *
+     *   @param fromFile
+     *       the file from which the path is relative
+     *   @param relative
+     *       the relative path obtained from getRelativePath
+     */
+    [must_use]
+    void setRelativePath(in nsIFile fromFile, in AUTF8String relativeDesc);
+};
+
+%{C++
+#ifdef MOZILLA_INTERNAL_API
+#include "nsDirectoryServiceUtils.h"
+#endif
+%}
diff --git a/xpcom/io/nsIIOUtil.idl b/xpcom/io/nsIIOUtil.idl
new file mode 100644
index 000000000..577ba4046
--- /dev/null
+++ b/xpcom/io/nsIIOUtil.idl
@@ -0,0 +1,34 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIInputStream;
+interface nsIOutputStream;
+
+/**
+ * nsIIOUtil provdes various xpcom/io-related utility methods.
+ */
+[scriptable, uuid(e8152f7f-4209-4c63-ad23-c3d2aa0c5a49)]
+interface nsIIOUtil : nsISupports
+{
+  /**
+   * Test whether an input stream is buffered.  See nsStreamUtils.h
+   * documentation for NS_InputStreamIsBuffered for the definition of
+   * "buffered" used here and for edge-case behavior.
+   *
+   * @throws NS_ERROR_INVALID_POINTER if null is passed in.
+   */
+  boolean inputStreamIsBuffered(in nsIInputStream aStream);
+
+  /**
+   * Test whether an output stream is buffered.  See nsStreamUtils.h
+   * documentation for NS_OutputStreamIsBuffered for the definition of
+   * "buffered" used here and for edge-case behavior.
+   *
+   * @throws NS_ERROR_INVALID_POINTER if null is passed in.
+   */
+  boolean outputStreamIsBuffered(in nsIOutputStream aStream);
+};
diff --git a/xpcom/io/nsIInputStream.idl b/xpcom/io/nsIInputStream.idl
new file mode 100644
index 000000000..b2f165274
--- /dev/null
+++ b/xpcom/io/nsIInputStream.idl
@@ -0,0 +1,147 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIInputStream;
+
+%{C++
+/**
+ * The signature of the writer function passed to ReadSegments. This
+ * is the "consumer" of data that gets read from the stream's buffer.
+ *
+ * @param aInStream stream being read
+ * @param aClosure opaque parameter passed to ReadSegments
+ * @param aFromSegment pointer to memory owned by the input stream.  This is
+ *                     where the writer function should start consuming data.
+ * @param aToOffset amount of data already consumed by this writer during this
+ *                  ReadSegments call.  This is also the sum of the aWriteCount
+ *                  returns from this writer over the previous invocations of
+ *                  the writer by this ReadSegments call.
+ * @param aCount Number of bytes available to be read starting at aFromSegment
+ * @param [out] aWriteCount number of bytes read by this writer function call
+ *
+ * Implementers should return the following:
+ *
+ * @return NS_OK and (*aWriteCount > 0) if consumed some data
+ * @return <any-error> if not interested in consuming any data
+ *
+ * Errors are never passed to the caller of ReadSegments.
+ *
+ * NOTE: returning NS_OK and (*aWriteCount = 0) has undefined behavior.
+ */
+typedef nsresult (*nsWriteSegmentFun)(nsIInputStream *aInStream,
+                                      void *aClosure,
+                                      const char *aFromSegment,
+                                      uint32_t aToOffset,
+                                      uint32_t aCount,
+                                      uint32_t *aWriteCount);
+%}
+
+native nsWriteSegmentFun(nsWriteSegmentFun);
+
+/**
+ * nsIInputStream
+ *
+ * An interface describing a readable stream of data.  An input stream may be
+ * "blocking" or "non-blocking" (see the IsNonBlocking method).  A blocking
+ * input stream may suspend the calling thread in order to satisfy a call to
+ * Close, Available, Read, or ReadSegments.  A non-blocking input stream, on
+ * the other hand, must not block the calling thread of execution.
+ *
+ * NOTE: blocking input streams are often read on a background thread to avoid
+ * locking up the main application thread.  For this reason, it is generally
+ * the case that a blocking input stream should be implemented using thread-
+ * safe AddRef and Release.
+ */
+[scriptable, uuid(53cdbc97-c2d7-4e30-b2c3-45b2ee79db18)]
+interface nsIInputStream : nsISupports
+{
+    /** 
+     * Close the stream.  This method causes subsequent calls to Read and
+     * ReadSegments to return 0 bytes read to indicate end-of-file.  Any
+     * subsequent calls to Available should throw NS_BASE_STREAM_CLOSED.
+     */
+    void close();
+
+    /**
+     * Determine number of bytes available in the stream.  A non-blocking
+     * stream that does not yet have any data to read should return 0 bytes
+     * from this method (i.e., it must not throw the NS_BASE_STREAM_WOULD_BLOCK
+     * exception).
+     * 
+     * In addition to the number of bytes available in the stream, this method
+     * also informs the caller of the current status of the stream.  A stream
+     * that is closed will throw an exception when this method is called.  That
+     * enables the caller to know the condition of the stream before attempting
+     * to read from it.  If a stream is at end-of-file, but not closed, then
+     * this method returns 0 bytes available.  (Note: some nsIInputStream
+     * implementations automatically close when eof is reached; some do not).
+     *
+     * @return number of bytes currently available in the stream.
+     *
+     * @throws NS_BASE_STREAM_CLOSED if the stream is closed normally.
+     * @throws <other-error> if the stream is closed due to some error
+     *   condition
+     */
+    unsigned long long available();
+
+    /** 
+     * Read data from the stream.
+     *
+     * @param aBuf the buffer into which the data is to be read
+     * @param aCount the maximum number of bytes to be read
+     *
+     * @return number of bytes read (may be less than aCount).
+     * @return 0 if reached end-of-file
+     *
+     * @throws NS_BASE_STREAM_WOULD_BLOCK if reading from the input stream would
+     *   block the calling thread (non-blocking mode only)
+     * @throws <other-error> on failure
+     *
+     * NOTE: this method should not throw NS_BASE_STREAM_CLOSED.
+     */
+    [noscript] unsigned long read(in charPtr aBuf, in unsigned long aCount);
+
+    /**
+     * Low-level read method that provides access to the stream's underlying
+     * buffer.  The writer function may be called multiple times for segmented
+     * buffers.  ReadSegments is expected to keep calling the writer until
+     * either there is nothing left to read or the writer returns an error.
+     * ReadSegments should not call the writer with zero bytes to consume.
+     *
+     * @param aWriter the "consumer" of the data to be read
+     * @param aClosure opaque parameter passed to writer 
+     * @param aCount the maximum number of bytes to be read
+     *
+     * @return number of bytes read (may be less than aCount)
+     * @return 0 if reached end-of-file (or if aWriter refused to consume data)
+     *
+     * @throws NS_BASE_STREAM_WOULD_BLOCK if reading from the input stream would
+     *   block the calling thread (non-blocking mode only)
+     * @throws NS_ERROR_NOT_IMPLEMENTED if the stream has no underlying buffer
+     * @throws <other-error> on failure
+     *
+     * NOTE: this function may be unimplemented if a stream has no underlying
+     * buffer (e.g., socket input stream).
+     *
+     * NOTE: this method should not throw NS_BASE_STREAM_CLOSED.
+     */
+    [noscript] unsigned long readSegments(in nsWriteSegmentFun aWriter,
+                                          in voidPtr aClosure,
+                                          in unsigned long aCount);
+
+    /**
+     * @return true if stream is non-blocking
+     *
+     * NOTE: reading from a blocking input stream will block the calling thread
+     * until at least one byte of data can be extracted from the stream.
+     *
+     * NOTE: a non-blocking input stream may implement nsIAsyncInputStream to
+     * provide consumers with a way to wait for the stream to have more data
+     * once its read method is unable to return any data without blocking.
+     */
+    boolean isNonBlocking();
+};
diff --git a/xpcom/io/nsIInputStreamTee.idl b/xpcom/io/nsIInputStreamTee.idl
new file mode 100644
index 000000000..953be7a7c
--- /dev/null
+++ b/xpcom/io/nsIInputStreamTee.idl
@@ -0,0 +1,42 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIInputStream.idl"
+
+interface nsIOutputStream;
+interface nsIEventTarget;
+
+/**
+ * A nsIInputStreamTee is a wrapper for an input stream, that when read
+ * reads the specified amount of data from its |source| and copies that
+ * data to its |sink|.  |sink| must be a blocking output stream.
+ */
+[scriptable, uuid(90a9d790-3bca-421e-a73b-98f68e13c917)]
+interface nsIInputStreamTee : nsIInputStream
+{
+    attribute nsIInputStream source;
+    attribute nsIOutputStream sink;
+    
+    /**
+     * If |eventTarget| is set, copying to sink is done asynchronously using
+     * the event-target (e.g. a thread). If |eventTarget| is not set, copying
+     * to sink happens synchronously while reading from the source.
+     */
+    attribute nsIEventTarget eventTarget;
+};
+
+%{C++
+// factory methods
+extern nsresult
+NS_NewInputStreamTee(nsIInputStream **tee, // read from this input stream
+                     nsIInputStream *source,
+                     nsIOutputStream *sink);
+                     
+extern nsresult
+NS_NewInputStreamTeeAsync(nsIInputStream **tee, // read from this input stream
+                     nsIInputStream *source,
+                     nsIOutputStream *sink,
+                     nsIEventTarget *eventTarget);
+%}
diff --git a/xpcom/io/nsILineInputStream.idl b/xpcom/io/nsILineInputStream.idl
new file mode 100644
index 000000000..4a8eff42b
--- /dev/null
+++ b/xpcom/io/nsILineInputStream.idl
@@ -0,0 +1,26 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+[scriptable, uuid(c97b466c-1e6e-4773-a4ab-2b2b3190a7a6)]
+interface nsILineInputStream : nsISupports
+{
+  /**
+   * Read a single line from the stream, where a line is a 
+   * possibly zero length sequence of 8bit chars terminated by a
+   * CR, LF, CRLF, LFCR, or eof.
+   * The line terminator is not returned.
+   * @retval false
+   *         End of file. This line is the last line of the file
+   *         (aLine is valid).
+   * @retval true
+   *         The file contains further lines.
+   * @note Do not mix readLine with other read functions.
+   *       Doing so can cause various problems and is not supported.
+   */
+  boolean readLine(out ACString aLine);
+};
diff --git a/xpcom/io/nsILocalFile.idl b/xpcom/io/nsILocalFile.idl
new file mode 100644
index 000000000..cead3e3f4
--- /dev/null
+++ b/xpcom/io/nsILocalFile.idl
@@ -0,0 +1,17 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIFile.idl"
+
+/**
+ * An empty interface to provide backwards compatibility for existing code.
+ *
+ * @see nsIFile
+ */
+[scriptable, builtinclass, uuid(7ba8c6ba-2ce2-48b1-bd60-4c32aac35f9c)]
+interface nsILocalFile : nsIFile
+{
+};
+
diff --git a/xpcom/io/nsILocalFileMac.idl b/xpcom/io/nsILocalFileMac.idl
new file mode 100644
index 000000000..d8655449b
--- /dev/null
+++ b/xpcom/io/nsILocalFileMac.idl
@@ -0,0 +1,179 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsILocalFile.idl"
+
+%{C++
+#include <Carbon/Carbon.h>
+#include <CoreFoundation/CoreFoundation.h>
+%}
+
+      native OSType(OSType);
+      native FSSpec(FSSpec);
+      native FSRef(FSRef);
+[ptr] native FSRefPtr(FSRef);
+      native CFURLRef(CFURLRef);
+
+[scriptable, builtinclass, uuid(623eca5b-c25d-4e27-be5a-789a66c4b2f7)]
+interface nsILocalFileMac : nsILocalFile
+{
+   /**
+    * initWithCFURL
+    *
+    * Init this object with a CFURLRef
+    *
+    * NOTE: Supported only for XP_MACOSX
+    * NOTE: If the path of the CFURL is /a/b/c, at least a/b must exist beforehand.
+    *
+    * @param   aCFURL         the CoreFoundation URL
+    *
+    */
+  [noscript] void initWithCFURL(in CFURLRef aCFURL);
+
+   /**
+    * initWithFSRef
+    *
+    * Init this object with an FSRef
+    *
+    * NOTE: Supported only for XP_MACOSX
+    *
+    * @param   aFSRef         the native FSRef
+    *
+    */
+  [noscript] void initWithFSRef([const] in FSRefPtr aFSRef);
+
+    /**
+    * getCFURL
+    *
+    * Returns the CFURLRef of the file object. The caller is
+    * responsible for calling CFRelease() on it.
+    *
+    * NOTE: Observes the state of the followLinks attribute.
+    * If the file object is an alias and followLinks is TRUE, returns
+    * the target of the alias. If followLinks is FALSE, returns
+    * the unresolved alias file.
+    *
+    * NOTE: Supported only for XP_MACOSX
+    *
+    * @return
+    *  
+    */ 
+  [noscript] CFURLRef getCFURL();
+ 
+    /**
+    * getFSRef
+    *
+    * Returns the FSRef of the file object.
+    *
+    * NOTE: Observes the state of the followLinks attribute.
+    * If the file object is an alias and followLinks is TRUE, returns
+    * the target of the alias. If followLinks is FALSE, returns
+    * the unresolved alias file.
+    *
+    * NOTE: Supported only for XP_MACOSX
+    *
+    * @return
+    *  
+    */ 
+  [noscript] FSRef getFSRef();
+   
+   /**
+    * getFSSpec
+    *
+    * Returns the FSSpec of the file object.
+    *
+    * NOTE: Observes the state of the followLinks attribute.
+    * If the file object is an alias and followLinks is TRUE, returns
+    * the target of the alias. If followLinks is FALSE, returns
+    * the unresolved alias file.
+    *
+    * @return
+    *  
+    */ 
+  [noscript] FSSpec getFSSpec();
+
+   /**
+    * fileSizeWithResFork
+    * 
+    * Returns the combined size of both the data fork and the resource
+    * fork (if present) rather than just the size of the data fork
+    * as returned by GetFileSize()
+    *
+    */
+   readonly attribute int64_t fileSizeWithResFork;
+
+   /**
+    * fileType, creator
+    *
+    * File type and creator attributes
+    *
+    */
+   [noscript] attribute OSType fileType;
+   [noscript] attribute OSType fileCreator;
+
+   /**
+    * launchWithDoc
+    *
+    * Launch the application that this file points to with a document.
+    *
+    * @param   aDocToLoad          Must not be NULL. If no document, use nsIFile::launch
+    * @param   aLaunchInBackground TRUE if the application should not come to the front.
+    *
+    */
+   void launchWithDoc(in nsIFile aDocToLoad, in boolean aLaunchInBackground);
+
+   /**
+    * openDocWithApp
+    *
+    * Open the document that this file points to with the given application.
+    *
+    * @param   aAppToOpenWith      The application with  which to open the document.
+    *                              If NULL, the creator code of the document is used
+    *                              to determine the application.
+    * @param   aLaunchInBackground TRUE if the application should not come to the front.
+    *
+    */
+   void openDocWithApp(in nsIFile aAppToOpenWith, in boolean aLaunchInBackground);
+
+   /**
+    * isPackage
+    *
+    * returns true if a directory is determined to be a package under Mac OS 9/X
+    *
+    */
+   boolean isPackage();
+
+   /**
+    * bundleDisplayName
+    *
+    * returns the display name of the application bundle (usually the human 
+    * readable name of the application)
+    */
+   readonly attribute AString bundleDisplayName;
+
+   /**
+    * bundleIdentifier
+    *
+    * returns the identifier of the bundle
+    */
+   readonly attribute AUTF8String bundleIdentifier;
+
+    /**
+     * Last modified time of a bundle's contents (as opposed to its package
+     * directory).  Our convention is to make the bundle's Info.plist file
+     * stand in for the rest of its contents -- since this file contains the
+     * bundle's version information and other identifiers.  For non-bundles
+     * this is the same as lastModifiedTime.
+     */
+    readonly attribute int64_t bundleContentsLastModifiedTime;
+};
+
+%{C++
+extern "C"
+{
+NS_EXPORT nsresult NS_NewLocalFileWithFSRef(const FSRef* aFSRef, bool aFollowSymlinks, nsILocalFileMac** result);
+NS_EXPORT nsresult NS_NewLocalFileWithCFURL(const CFURLRef aURL, bool aFollowSymlinks, nsILocalFileMac** result);
+}
+%}
diff --git a/xpcom/io/nsILocalFileWin.idl b/xpcom/io/nsILocalFileWin.idl
new file mode 100644
index 000000000..c036cb96b
--- /dev/null
+++ b/xpcom/io/nsILocalFileWin.idl
@@ -0,0 +1,121 @@
+/* -*- Mode: Java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include "nsILocalFile.idl"
+
+%{C++
+struct PRFileDesc;
+%}
+
+[ptr] native PRFileDescStar(PRFileDesc);
+
+[scriptable, builtinclass, uuid(e7a3a954-384b-4aeb-a5f7-55626b0de9be)]
+interface nsILocalFileWin : nsILocalFile
+{
+    /**
+     *  initWithCommandLine
+     *
+     *  Initialize this object based on the main app path of a commandline
+     *  handler.
+     *
+     *   @param aCommandLine
+     *       the commandline to parse an app path out of.
+     */
+    void initWithCommandLine(in AString aCommandLine);
+   /**
+    * getVersionInfoValue
+    *
+    * Retrieve a metadata field from the file's VERSIONINFO block.
+    * Throws NS_ERROR_FAILURE if no value is found, or the value is empty.
+    *
+    * @param   aField         The field to look up.
+    *
+    */
+    AString getVersionInfoField(in string aField);
+
+    /**
+     * The canonical path of the file, which avoids short/long
+     * pathname inconsistencies. The nsIFile persistent
+     * descriptor is not guaranteed to be canonicalized (it may
+     * persist either the long or the short path name). The format of
+     * the canonical path will vary with the underlying file system:
+     * it will typically be the short pathname on filesystems that
+     * support both short and long path forms.
+     */
+    readonly attribute AString canonicalPath;
+    [noscript] readonly attribute ACString nativeCanonicalPath;
+
+    /**
+     * Windows specific file attributes.
+     */
+
+    /*
+     * WFA_SEARCH_INDEXED: Generally the default on files in Windows except
+     * those created in temp locations. Valid on XP and up. When set the
+     * file or directory is marked to be indexed by desktop search services.
+     */
+    const unsigned long WFA_SEARCH_INDEXED = 1;
+
+    /*
+     * WFA_READONLY: Whether the file is readonly or not.
+     */
+    const unsigned long WFA_READONLY = 2;
+
+    /*
+     * WFA_READWRITE: Used to clear the readonly attribute.
+     */
+    const unsigned long WFA_READWRITE = 4;
+
+    /**
+     * fileAttributesWin
+     *
+     * Set or get windows specific file attributes.
+     * 
+     * Throws NS_ERROR_FILE_INVALID_PATH for an invalid file.
+     * Throws NS_ERROR_FAILURE if the set or get fails.
+     */
+    attribute unsigned long fileAttributesWin;
+
+    /**
+     * setShortcut
+     *
+     * Creates the specified shortcut, or updates it if it already exists.
+     *
+     * If the shortcut is being updated (i.e. the shortcut already exists),
+     * any excluded parameters will remain unchanged in the shortcut file.
+     * For example, if you want to change the description of a specific
+     * shortcut but keep the target, working dir, args, and icon the same,
+     * pass null for those parameters and only pass in a value for the
+     * description.
+     *
+     * If the shortcut does not already exist and targetFile is not specified,
+     * setShortcut will throw NS_ERROR_FILE_TARGET_DOES_NOT_EXIST.
+     *
+     * @param targetFile      the path that the shortcut should target
+     * @param workingDir      the working dir that should be set for the shortcut
+     * @param args            the args string that should be set for the shortcut
+     * @param description     the description that should be set for the shortcut
+     * @param iconFile        the file containing an icon to be used for this
+                              shortcut
+     * @param iconIndex       this value selects a specific icon from within
+                              iconFile.  If iconFile contains only one icon, this
+                              value should be 0.
+     */
+     void setShortcut([optional] in nsIFile targetFile,
+                      [optional] in nsIFile workingDir,
+                      [optional] in wstring args,
+                      [optional] in wstring description,
+                      [optional] in nsIFile iconFile,
+                      [optional] in long iconIndex);
+
+    /**
+     * Identical to nsIFile::openNSPRFileDesc except it also uses the
+     * FILE_SHARE_DELETE flag.
+    */
+    [noscript] PRFileDescStar openNSPRFileDescShareDelete(in long flags,
+                                                          in long mode);
+};
+
diff --git a/xpcom/io/nsIMultiplexInputStream.idl b/xpcom/io/nsIMultiplexInputStream.idl
new file mode 100644
index 000000000..d42adcbd4
--- /dev/null
+++ b/xpcom/io/nsIMultiplexInputStream.idl
@@ -0,0 +1,55 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIInputStream.idl"
+
+/**
+ * The multiplex stream concatenates a list of input streams into a single
+ * stream.
+ */
+
+[scriptable, uuid(a076fd12-1dd1-11b2-b19a-d53b5dffaade)]
+interface nsIMultiplexInputStream : nsIInputStream
+{
+    /**
+     * Number of streams in this multiplex-stream
+     */
+    readonly attribute unsigned long count;
+
+    /**
+     * Appends a stream to the end of the streams. The cursor of the stream
+     * should be located at the beginning of the stream if the implementation
+     * of this nsIMultiplexInputStream also is used as an nsISeekableStream.
+     * @param stream  stream to append
+     */
+    void appendStream(in nsIInputStream stream);
+
+    /**
+     * Insert a stream at specified index.  If the cursor of this stream is at
+     * the beginning of the stream at index, the cursor will be placed at the
+     * beginning of the inserted stream instead.
+     * The cursor of the new stream should be located at the beginning of the
+     * stream if the implementation of this nsIMultiplexInputStream also is
+     * used as an nsISeekableStream.
+     * @param stream  stream to insert
+     * @param index   index to insert stream at, must be <= count
+     */
+    void insertStream(in nsIInputStream stream, in unsigned long index);
+
+    /**
+     * Remove stream at specified index. If this stream is the one currently
+     * being read the readcursor is moved to the beginning of the next
+     * stream
+     * @param index   remove stream at this index, must be < count
+     */
+    void removeStream(in unsigned long index);
+
+    /**
+     * Get stream at specified index.
+     * @param index   return stream at this index, must be < count
+     * @return        stream at specified index
+     */
+    nsIInputStream getStream(in unsigned long index);
+};
diff --git a/xpcom/io/nsIOUtil.cpp b/xpcom/io/nsIOUtil.cpp
new file mode 100644
index 000000000..d583dd75b
--- /dev/null
+++ b/xpcom/io/nsIOUtil.cpp
@@ -0,0 +1,32 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIOUtil.h"
+#include "nsIInputStream.h"
+#include "nsIOutputStream.h"
+#include "nsStreamUtils.h"
+
+NS_IMPL_ISUPPORTS(nsIOUtil, nsIIOUtil)
+
+NS_IMETHODIMP
+nsIOUtil::InputStreamIsBuffered(nsIInputStream* aStream, bool* aResult)
+{
+  if (NS_WARN_IF(!aStream)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  *aResult = NS_InputStreamIsBuffered(aStream);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsIOUtil::OutputStreamIsBuffered(nsIOutputStream* aStream, bool* aResult)
+{
+  if (NS_WARN_IF(!aStream)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  *aResult = NS_OutputStreamIsBuffered(aStream);
+  return NS_OK;
+}
diff --git a/xpcom/io/nsIOUtil.h b/xpcom/io/nsIOUtil.h
new file mode 100644
index 000000000..47b02a02e
--- /dev/null
+++ b/xpcom/io/nsIOUtil.h
@@ -0,0 +1,27 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsIOUtil_h__
+#define nsIOUtil_h__
+
+#define NS_IOUTIL_CID                                                \
+{ 0xeb833911, 0x4f49, 0x4623,                                        \
+    { 0x84, 0x5f, 0xe5, 0x8a, 0x8e, 0x6d, 0xe4, 0xc2 } }
+
+
+#include "nsIIOUtil.h"
+#include "mozilla/Attributes.h"
+
+class nsIOUtil final : public nsIIOUtil
+{
+  ~nsIOUtil() {}
+
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIIOUTIL
+};
+
+#endif /* nsIOUtil_h__ */
diff --git a/xpcom/io/nsIObjectInputStream.idl b/xpcom/io/nsIObjectInputStream.idl
new file mode 100644
index 000000000..c482d3b89
--- /dev/null
+++ b/xpcom/io/nsIObjectInputStream.idl
@@ -0,0 +1,53 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIBinaryInputStream.idl"
+
+/**
+ * @see nsIObjectOutputStream
+ * @see nsIBinaryInputStream
+ */
+
+[scriptable, uuid(6c248606-4eae-46fa-9df0-ba58502368eb)]
+interface nsIObjectInputStream : nsIBinaryInputStream
+{
+    /**
+     * Read an object from this stream to satisfy a strong or weak reference
+     * to one of its interfaces.  If the interface was not along the primary
+     * inheritance chain ending in the "root" or XPCOM-identity nsISupports,
+     * readObject will QueryInterface from the deserialized object root to the
+     * correct interface, which was specified when the object was serialized.
+     *
+     * @see nsIObjectOutputStream
+     */
+    nsISupports readObject(in boolean aIsStrongRef);
+
+    [notxpcom] nsresult readID(out nsID aID);
+
+    /**
+     * Optimized deserialization support -- see nsIStreamBufferAccess.idl.
+     */
+    [notxpcom] charPtr getBuffer(in uint32_t aLength, in uint32_t aAlignMask);
+    [notxpcom] void    putBuffer(in charPtr aBuffer, in uint32_t aLength);
+};
+
+%{C++
+
+inline nsresult
+NS_ReadOptionalObject(nsIObjectInputStream* aStream, bool aIsStrongRef,
+                      nsISupports* *aResult)
+{
+    bool nonnull;
+    nsresult rv = aStream->ReadBoolean(&nonnull);
+    if (NS_SUCCEEDED(rv)) {
+        if (nonnull)
+            rv = aStream->ReadObject(aIsStrongRef, aResult);
+        else
+            *aResult = nullptr;
+    }
+    return rv;
+}
+
+%}
diff --git a/xpcom/io/nsIObjectOutputStream.idl b/xpcom/io/nsIObjectOutputStream.idl
new file mode 100644
index 000000000..3ef6711d4
--- /dev/null
+++ b/xpcom/io/nsIObjectOutputStream.idl
@@ -0,0 +1,97 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIBinaryOutputStream.idl"
+
+/**
+ * @See nsIObjectInputStream
+ * @See nsIBinaryOutputStream
+ */
+
+[scriptable, uuid(92c898ac-5fde-4b99-87b3-5d486422094b)]
+interface nsIObjectOutputStream : nsIBinaryOutputStream
+{
+    /**
+     * Write the object whose "root" or XPCOM-identity nsISupports is aObject.
+     * The cause for writing this object is a strong or weak reference, so the
+     * aIsStrongRef argument must tell which kind of pointer is being followed
+     * here during serialization.
+     *
+     * If the object has only one strong reference in the serialization and no
+     * weak refs, use writeSingleRefObject.  This is a valuable optimization:
+     * it saves space in the stream, and cycles on both ends of the process.
+     *
+     * If the reference being serialized is a pointer to an interface not on
+     * the primary inheritance chain ending in the root nsISupports, you must
+     * call writeCompoundObject instead of this method.
+     */
+    void writeObject(in nsISupports aObject, in boolean aIsStrongRef);
+
+    /**
+     * Write an object referenced singly and strongly via its root nsISupports
+     * or a subclass of its root nsISupports.  There must not be other refs to
+     * aObject in memory, or in the serialization.
+     */
+    void writeSingleRefObject(in nsISupports aObject);
+
+    /**
+     * Write the object referenced by an interface pointer at aObject that
+     * inherits from a non-primary nsISupports, i.e., a reference to one of
+     * the multiply inherited interfaces derived from an nsISupports other
+     * than the root or XPCOM-identity nsISupports; or a reference to an
+     * inner object in the case of true XPCOM aggregation.  aIID identifies
+     * this interface.
+     */
+    void writeCompoundObject(in nsISupports aObject,
+                             in nsIIDRef aIID,
+                             in boolean aIsStrongRef);
+
+    void writeID(in nsIDRef aID);
+
+    /**
+     * Optimized serialization support -- see nsIStreamBufferAccess.idl.
+     */
+    [notxpcom] charPtr getBuffer(in uint32_t aLength, in uint32_t aAlignMask);
+    [notxpcom] void    putBuffer(in charPtr aBuffer, in uint32_t aLength);
+};
+
+%{C++
+
+inline nsresult
+NS_WriteOptionalObject(nsIObjectOutputStream* aStream, nsISupports* aObject,
+                       bool aIsStrongRef)
+{
+    bool nonnull = (aObject != nullptr);
+    nsresult rv = aStream->WriteBoolean(nonnull);
+    if (NS_SUCCEEDED(rv) && nonnull)
+        rv = aStream->WriteObject(aObject, aIsStrongRef);
+    return rv;
+}
+
+inline nsresult
+NS_WriteOptionalSingleRefObject(nsIObjectOutputStream* aStream,
+                                nsISupports* aObject)
+{
+    bool nonnull = (aObject != nullptr);
+    nsresult rv = aStream->WriteBoolean(nonnull);
+    if (NS_SUCCEEDED(rv) && nonnull)
+        rv = aStream->WriteSingleRefObject(aObject);
+    return rv;
+}
+
+inline nsresult
+NS_WriteOptionalCompoundObject(nsIObjectOutputStream* aStream,
+                               nsISupports* aObject,
+                               const nsIID& aIID,
+                               bool aIsStrongRef)
+{
+    bool nonnull = (aObject != nullptr);
+    nsresult rv = aStream->WriteBoolean(nonnull);
+    if (NS_SUCCEEDED(rv) && nonnull)
+        rv = aStream->WriteCompoundObject(aObject, aIID, aIsStrongRef);
+    return rv;
+}
+
+%}
diff --git a/xpcom/io/nsIOutputStream.idl b/xpcom/io/nsIOutputStream.idl
new file mode 100644
index 000000000..0e04a3910
--- /dev/null
+++ b/xpcom/io/nsIOutputStream.idl
@@ -0,0 +1,145 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIOutputStream;
+interface nsIInputStream;
+
+%{C++
+/**
+ * The signature for the reader function passed to WriteSegments. This 
+ * is the "provider" of data that gets written into the stream's buffer.
+ *
+ * @param aOutStream stream being written to
+ * @param aClosure opaque parameter passed to WriteSegments
+ * @param aToSegment pointer to memory owned by the output stream
+ * @param aFromOffset amount already written (since WriteSegments was called)
+ * @param aCount length of toSegment
+ * @param aReadCount number of bytes written
+ *
+ * Implementers should return the following:
+ *
+ * @throws <any-error> if not interested in providing any data
+ *
+ * Errors are never passed to the caller of WriteSegments.
+ */
+typedef nsresult (*nsReadSegmentFun)(nsIOutputStream *aOutStream,
+                                     void *aClosure,
+                                     char *aToSegment,
+                                     uint32_t aFromOffset,
+                                     uint32_t aCount,
+                                     uint32_t *aReadCount);
+%}
+
+native nsReadSegmentFun(nsReadSegmentFun);
+
+/**
+ * nsIOutputStream
+ *
+ * An interface describing a writable stream of data.  An output stream may be
+ * "blocking" or "non-blocking" (see the IsNonBlocking method).  A blocking
+ * output stream may suspend the calling thread in order to satisfy a call to
+ * Close, Flush, Write, WriteFrom, or WriteSegments.  A non-blocking output
+ * stream, on the other hand, must not block the calling thread of execution.
+ *
+ * NOTE: blocking output streams are often written to on a background thread to
+ * avoid locking up the main application thread.  For this reason, it is
+ * generally the case that a blocking output stream should be implemented using
+ * thread- safe AddRef and Release.
+ */
+[scriptable, uuid(0d0acd2a-61b4-11d4-9877-00c04fa0cf4a)]
+interface nsIOutputStream : nsISupports
+{
+    /** 
+     * Close the stream. Forces the output stream to flush any buffered data.
+     *
+     * @throws NS_BASE_STREAM_WOULD_BLOCK if unable to flush without blocking 
+     *   the calling thread (non-blocking mode only)
+     */
+    void close();
+
+    /**
+     * Flush the stream.
+     *
+     * @throws NS_BASE_STREAM_WOULD_BLOCK if unable to flush without blocking 
+     *   the calling thread (non-blocking mode only)
+     */
+    void flush();
+
+    /**
+     * Write data into the stream.
+     *
+     * @param aBuf the buffer containing the data to be written
+     * @param aCount the maximum number of bytes to be written
+     *
+     * @return number of bytes written (may be less than aCount)
+     *
+     * @throws NS_BASE_STREAM_WOULD_BLOCK if writing to the output stream would
+     *   block the calling thread (non-blocking mode only)
+     * @throws <other-error> on failure
+     */
+    unsigned long write(in string aBuf, in unsigned long aCount);
+
+    /**
+     * Writes data into the stream from an input stream.
+     *
+     * @param aFromStream the stream containing the data to be written
+     * @param aCount the maximum number of bytes to be written
+     *
+     * @return number of bytes written (may be less than aCount)
+     *
+     * @throws NS_BASE_STREAM_WOULD_BLOCK if writing to the output stream would
+     *    block the calling thread (non-blocking mode only). This failure
+     *    means no bytes were transferred.
+     * @throws <other-error> on failure
+     *
+     * NOTE: This method is defined by this interface in order to allow the
+     * output stream to efficiently copy the data from the input stream into
+     * its internal buffer (if any). If this method was provided as an external
+     * facility, a separate char* buffer would need to be used in order to call
+     * the output stream's other Write method.
+     */
+    unsigned long writeFrom(in nsIInputStream aFromStream,
+                            in unsigned long aCount);
+
+    /**
+     * Low-level write method that has access to the stream's underlying buffer.
+     * The reader function may be called multiple times for segmented buffers.
+     * WriteSegments is expected to keep calling the reader until either there
+     * is nothing left to write or the reader returns an error.  WriteSegments
+     * should not call the reader with zero bytes to provide.
+     *
+     * @param aReader the "provider" of the data to be written
+     * @param aClosure opaque parameter passed to reader
+     * @param aCount the maximum number of bytes to be written
+     *
+     * @return number of bytes written (may be less than aCount)
+     *
+     * @throws NS_BASE_STREAM_WOULD_BLOCK if writing to the output stream would
+     *    block the calling thread (non-blocking mode only). This failure
+     *    means no bytes were transferred.
+     * @throws NS_ERROR_NOT_IMPLEMENTED if the stream has no underlying buffer
+     * @throws <other-error> on failure
+     *
+     * NOTE: this function may be unimplemented if a stream has no underlying
+     * buffer (e.g., socket output stream).
+     */
+    [noscript] unsigned long writeSegments(in nsReadSegmentFun aReader,
+                                           in voidPtr aClosure,
+                                           in unsigned long aCount);
+
+    /**
+     * @return true if stream is non-blocking
+     *
+     * NOTE: writing to a blocking output stream will block the calling thread
+     * until all given data can be consumed by the stream.
+     *
+     * NOTE: a non-blocking output stream may implement nsIAsyncOutputStream to
+     * provide consumers with a way to wait for the stream to accept more data
+     * once its write method is unable to accept any data without blocking.
+     */
+    boolean isNonBlocking();
+};
diff --git a/xpcom/io/nsIPipe.idl b/xpcom/io/nsIPipe.idl
new file mode 100644
index 000000000..596be92e9
--- /dev/null
+++ b/xpcom/io/nsIPipe.idl
@@ -0,0 +1,171 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIAsyncInputStream;
+interface nsIAsyncOutputStream;
+
+/**
+ * nsIPipe represents an in-process buffer that can be read using nsIInputStream
+ * and written using nsIOutputStream.  The reader and writer of a pipe do not
+ * have to be on the same thread.  As a result, the pipe is an ideal mechanism
+ * to bridge data exchange between two threads.  For example, a worker thread
+ * might write data to a pipe from which the main thread will read.
+ *
+ * Each end of the pipe can be either blocking or non-blocking.  Recall that a
+ * non-blocking stream will return NS_BASE_STREAM_WOULD_BLOCK if it cannot be
+ * read or written to without blocking the calling thread.  For example, if you
+ * try to read from an empty pipe that has not yet been closed, then if that
+ * pipe's input end is non-blocking, then the read call will fail immediately
+ * with NS_BASE_STREAM_WOULD_BLOCK as the error condition.  However, if that
+ * pipe's input end is blocking, then the read call will not return until the
+ * pipe has data or until the pipe is closed.  This example presumes that the
+ * pipe is being filled asynchronously on some background thread.
+ *
+ * The pipe supports nsIAsyncInputStream and nsIAsyncOutputStream, which give
+ * the user of a non-blocking pipe the ability to wait for the pipe to become
+ * ready again.  For example, in the case of an empty non-blocking pipe, the
+ * user can call AsyncWait on the input end of the pipe to be notified when 
+ * the pipe has data to read (or when the pipe becomes closed).
+ *
+ * NS_NewPipe2 and NS_NewPipe provide convenient pipe constructors.  In most
+ * cases nsIPipe is not actually used.  It is usually enough to just get
+ * references to the pipe's input and output end.  In which case, the pipe is
+ * automatically closed when the respective pipe ends are released.
+ */
+[scriptable, uuid(25d0de93-685e-4ea4-95d3-d884e31df63c)]
+interface nsIPipe : nsISupports
+{
+    /**
+     * initialize this pipe
+     *
+     * @param nonBlockingInput
+     *        true specifies non-blocking input stream behavior
+     * @param nonBlockingOutput
+     *        true specifies non-blocking output stream behavior
+     * @param segmentSize
+     *        specifies the segment size in bytes (pass 0 to use default value)
+     * @param segmentCount
+     *        specifies the max number of segments (pass 0 to use default
+     *        value).   Passing UINT32_MAX here causes the pipe to have
+     *        "infinite" space.  This mode can be useful in some cases, but
+     *        should always be used with caution.  The default value for this
+     *        parameter is a finite value.
+     */
+    [must_use] void init(in boolean nonBlockingInput,
+                         in boolean nonBlockingOutput,
+                         in unsigned long segmentSize,
+                         in unsigned long segmentCount);
+
+    /**
+     * The pipe's input end, which also implements nsISearchableInputStream.
+     * Getting fails if the pipe hasn't been initialized.
+     */
+    [must_use] readonly attribute nsIAsyncInputStream inputStream;
+
+    /**
+     * The pipe's output end. Getting fails if the pipe hasn't been
+     * initialized.
+     */
+    [must_use] readonly attribute nsIAsyncOutputStream outputStream;
+};
+
+/**
+ * XXX this interface doesn't really belong in here.  It is here because
+ * currently nsPipeInputStream is the only implementation of this interface.
+ */
+[scriptable, uuid(8C39EF62-F7C9-11d4-98F5-001083010E9B)] 
+interface nsISearchableInputStream : nsISupports
+{
+    /**
+     * Searches for a string in the input stream. Since the stream has a notion
+     * of EOF, it is possible that the string may at some time be in the 
+     * buffer, but is is not currently found up to some offset. Consequently,
+     * both the found and not found cases return an offset:
+     *    if found, return offset where it was found
+     *    if not found, return offset of the first byte not searched
+     * In the case the stream is at EOF and the string is not found, the first
+     * byte not searched will correspond to the length of the buffer.
+     */
+    void search(in string forString, 
+                in boolean ignoreCase, 
+                out boolean found,
+                out unsigned long offsetSearchedTo);
+};
+
+%{C++
+
+class nsIInputStream;
+class nsIOutputStream;
+
+/**
+ * NS_NewPipe2
+ *
+ * This function supersedes NS_NewPipe.  It differs from NS_NewPipe in two
+ * major ways:
+ *  (1) returns nsIAsyncInputStream and nsIAsyncOutputStream, so it is
+ *      not necessary to QI in order to access these interfaces.
+ *  (2) the size of the pipe is determined by the number of segments
+ *      times the size of each segment.
+ *
+ * @param pipeIn
+ *        resulting input end of the pipe
+ * @param pipeOut
+ *        resulting output end of the pipe
+ * @param nonBlockingInput
+ *        true specifies non-blocking input stream behavior
+ * @param nonBlockingOutput
+ *        true specifies non-blocking output stream behavior
+ * @param segmentSize
+ *        specifies the segment size in bytes (pass 0 to use default value)
+ * @param segmentCount
+ *        specifies the max number of segments (pass 0 to use default value)
+ *        passing UINT32_MAX here causes the pipe to have "infinite" space.
+ *        this mode can be useful in some cases, but should always be used with
+ *        caution.  the default value for this parameter is a finite value.
+ */
+extern MOZ_MUST_USE nsresult
+NS_NewPipe2(nsIAsyncInputStream **pipeIn,
+            nsIAsyncOutputStream **pipeOut,
+            bool nonBlockingInput = false,
+            bool nonBlockingOutput = false,
+            uint32_t segmentSize = 0,
+            uint32_t segmentCount = 0);
+
+/**
+ * NS_NewPipe
+ *
+ * Preserved for backwards compatibility.  Plus, this interface is more
+ * amiable in certain contexts (e.g., when you don't need the pipe's async
+ * capabilities).
+ *
+ * @param pipeIn
+ *        resulting input end of the pipe
+ * @param pipeOut
+ *        resulting output end of the pipe
+ * @param segmentSize
+ *        specifies the segment size in bytes (pass 0 to use default value)
+ * @param maxSize
+ *        specifies the max size of the pipe (pass 0 to use default value)
+ *        number of segments is maxSize / segmentSize, and maxSize must be a
+ *        multiple of segmentSize.  passing UINT32_MAX here causes the
+ *        pipe to have "infinite" space.  this mode can be useful in some
+ *        cases, but should always be used with caution.  the default value
+ *        for this parameter is a finite value.
+ * @param nonBlockingInput
+ *        true specifies non-blocking input stream behavior
+ * @param nonBlockingOutput
+ *        true specifies non-blocking output stream behavior
+ */
+extern MOZ_MUST_USE nsresult
+NS_NewPipe(nsIInputStream **pipeIn,
+           nsIOutputStream **pipeOut,
+           uint32_t segmentSize = 0,
+           uint32_t maxSize = 0,
+           bool nonBlockingInput = false,
+           bool nonBlockingOutput = false);
+
+%}
diff --git a/xpcom/io/nsISafeOutputStream.idl b/xpcom/io/nsISafeOutputStream.idl
new file mode 100644
index 000000000..c62d85f07
--- /dev/null
+++ b/xpcom/io/nsISafeOutputStream.idl
@@ -0,0 +1,39 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * This interface provides a mechanism to control an output stream
+ * that takes care not to overwrite an existing target until it is known
+ * that all writes to the destination succeeded.
+ * 
+ * An object that supports this interface is intended to also support
+ * nsIOutputStream.
+ *
+ * For example, a file output stream that supports this interface writes to
+ * a temporary file, and moves it over the original file when |finish| is
+ * called only if the stream can be successfully closed and all writes
+ * succeeded.  If |finish| is called but something went wrong during
+ * writing, it will delete the temporary file and not touch the original.
+ * If the stream is closed by calling |close| directly, or the stream
+ * goes away, the original file will not be overwritten, and the temporary
+ * file will be deleted.
+ *
+ * Currently, this interface is implemented only for file output streams.
+ */
+[scriptable, uuid(5f914307-5c34-4e1f-8e32-ec749d25b27a)]
+interface nsISafeOutputStream : nsISupports
+{
+    /**
+     * Call this method to close the stream and cause the original target
+     * to be overwritten. Note: if any call to |write| failed to write out
+     * all of the data given to it, then calling this method will |close| the
+     * stream and return failure. Further, if closing the stream fails, this
+     * method will return failure. The original target will be overwritten only
+     * if all calls to |write| succeeded and the stream was successfully closed.
+     */
+    void finish();
+};
diff --git a/xpcom/io/nsIScriptableBase64Encoder.idl b/xpcom/io/nsIScriptableBase64Encoder.idl
new file mode 100644
index 000000000..641451805
--- /dev/null
+++ b/xpcom/io/nsIScriptableBase64Encoder.idl
@@ -0,0 +1,32 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIInputStream;
+
+/**
+ * nsIScriptableBase64Encoder efficiently encodes the contents
+ * of a nsIInputStream to a Base64 string.  This avoids the need
+ * to read the entire stream into a buffer, and only then do the
+ * Base64 encoding.
+ *
+ *  If you already have a buffer full of data, you should use
+ *  btoa instead!
+ */
+[scriptable, uuid(9479c864-d1f9-45ab-b7b9-28b907bd2ba9)]
+interface nsIScriptableBase64Encoder : nsISupports
+{
+  /**
+   *  These methods take an nsIInputStream and return a narrow or wide
+   *  string with the contents of the nsIInputStream base64 encoded.
+   *
+   *  The stream passed in must support ReadSegments and must not be
+   *  a non-blocking stream that will return NS_BASE_STREAM_WOULD_BLOCK.
+   *  If either of these restrictions are violated we will abort.
+   */
+  ACString encodeToCString(in nsIInputStream stream, in unsigned long length);
+  AString encodeToString(in nsIInputStream stream, in unsigned long length);
+};
diff --git a/xpcom/io/nsIScriptableInputStream.idl b/xpcom/io/nsIScriptableInputStream.idl
new file mode 100644
index 000000000..d9248f425
--- /dev/null
+++ b/xpcom/io/nsIScriptableInputStream.idl
@@ -0,0 +1,67 @@
+/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIInputStream;
+
+/**
+ * nsIScriptableInputStream provides scriptable access to an nsIInputStream
+ * instance.
+ */
+[scriptable, uuid(3fce9015-472a-4080-ac3e-cd875dbe361e)]
+interface nsIScriptableInputStream : nsISupports
+{ 
+    /** 
+     * Closes the stream. 
+     */
+    void close();
+
+    /**
+     * Wrap the given nsIInputStream with this nsIScriptableInputStream. 
+     *
+     * @param aInputStream parameter providing the stream to wrap 
+     */ 
+    void init(in nsIInputStream aInputStream); 
+
+    /**
+     * Return the number of bytes currently available in the stream 
+     *
+     * @return the number of bytes 
+     *
+     * @throws NS_BASE_STREAM_CLOSED if called after the stream has been closed
+     */ 
+    unsigned long long available(); 
+
+    /**
+     * Read data from the stream.
+     *
+     * WARNING: If the data contains a null byte, then this method will return
+     * a truncated string.
+     *
+     * @param aCount the maximum number of bytes to read 
+     *
+     * @return the data, which will be an empty string if the stream is at EOF.
+     *
+     * @throws NS_BASE_STREAM_CLOSED if called after the stream has been closed
+     * @throws NS_ERROR_NOT_INITIALIZED if init was not called
+     */ 
+    string read(in unsigned long aCount); 
+
+    /**
+     * Read data from the stream, including NULL bytes.
+     *
+     * @param aCount the maximum number of bytes to read.
+     *
+     * @return the data from the stream, which will be an empty string if EOF
+     *         has been reached.
+     *
+     * @throws NS_BASE_STREAM_WOULD_BLOCK if reading from the input stream
+     *         would block the calling thread (non-blocking mode only).
+     * @throws NS_ERROR_FAILURE if there are not enough bytes available to read
+     *         aCount amount of data.
+     */
+    ACString readBytes(in unsigned long aCount);
+};
diff --git a/xpcom/io/nsISeekableStream.idl b/xpcom/io/nsISeekableStream.idl
new file mode 100644
index 000000000..1be7ea60c
--- /dev/null
+++ b/xpcom/io/nsISeekableStream.idl
@@ -0,0 +1,74 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+/*
+ * nsISeekableStream
+ *
+ * Note that a stream might not implement all methods (e.g., a readonly stream 
+ * won't implement setEOF)
+ */
+
+#include "nsISupports.idl"
+
+[scriptable, uuid(8429d350-1040-4661-8b71-f2a6ba455980)]
+interface nsISeekableStream : nsISupports
+{
+    /* 
+     * Sets the stream pointer to the value of the 'offset' parameter 
+     */
+    const int32_t NS_SEEK_SET = 0;
+
+    /*  
+     * Sets the stream pointer to its current location plus the value 
+     * of the offset parameter. 
+     */
+    const int32_t NS_SEEK_CUR = 1;
+
+    /* 
+     * Sets the stream pointer to the size of the stream plus the value 
+     * of the offset parameter. 
+     */
+    const int32_t NS_SEEK_END = 2;
+
+    /**
+     *  seek
+     *
+     *  This method moves the stream offset of the steam implementing this
+     *  interface.
+     *
+     *   @param whence specifies how to interpret the 'offset' parameter in
+     *                 setting the stream offset associated with the implementing
+     *                 stream.
+     *     
+     *   @param offset specifies a value, in bytes, that is used in conjunction
+     *                 with the 'whence' parameter to set the stream offset of the 
+     *                 implementing stream.  A negative value causes seeking in 
+     *                 the reverse direction.
+     *
+     *   @throws NS_BASE_STREAM_CLOSED if called on a closed stream.
+     */
+    void seek(in long whence, in long long offset);
+
+    /**
+     *  tell
+     *
+     *  This method reports the current offset, in bytes, from the start of the 
+     *  stream. 
+     *
+     *   @throws NS_BASE_STREAM_CLOSED if called on a closed stream.
+     */
+    long long tell();
+
+
+    /**
+     *  setEOF
+     *
+     *  This method truncates the stream at the current offset.
+     *
+     *   @throws NS_BASE_STREAM_CLOSED if called on a closed stream.
+     */
+    void setEOF();
+};
diff --git a/xpcom/io/nsIStorageStream.idl b/xpcom/io/nsIStorageStream.idl
new file mode 100644
index 000000000..7d5061e23
--- /dev/null
+++ b/xpcom/io/nsIStorageStream.idl
@@ -0,0 +1,69 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIInputStream;
+interface nsIOutputStream;
+
+/**
+ * The nsIStorageStream interface maintains an internal data buffer that can be
+ * filled using a single output stream.  One or more independent input streams
+ * can be created to read the data from the buffer non-destructively.
+ */
+
+[scriptable, uuid(44a200fe-6c2b-4b41-b4e3-63e8c14e7c0d)]
+interface nsIStorageStream : nsISupports
+{
+    /**
+     *
+     * Initialize the stream, setting up the amount of space that will be
+     * allocated for the stream's backing-store.
+     *
+     * @param segmentSize
+     *        Size of each segment. Must be a power of two.
+     * @param maxSize
+     *        Maximum total size of this stream. length will always be less
+     *        than or equal to this value. Passing UINT32_MAX is safe.
+     */
+    void init(in uint32_t segmentSize, in uint32_t maxSize);
+
+    /**
+     * Get a reference to the one and only output stream for this instance.
+     * The zero-based startPosition argument is used is used to set the initial
+     * write cursor position.  The startPosition cannot be set larger than the
+     * current buffer length.  Calling this method has the side-effect of
+     * truncating the internal buffer to startPosition bytes.
+     */
+    nsIOutputStream getOutputStream(in int32_t startPosition);
+
+    /**
+     * Create a new input stream to read data (written by the singleton output
+     * stream) from the internal buffer.  Multiple, independent input streams
+     * can be created.
+     */
+    nsIInputStream newInputStream(in int32_t startPosition);
+
+    /** 
+     * The length attribute indicates the total number of bytes stored in the
+     * nsIStorageStream internal buffer, regardless of any consumption by input
+     * streams.  Assigning to the length field can be used to truncate the
+     * buffer data, but can not be used when either the instance's output
+     * stream is in use.
+     *
+     * @See #writeInProgress */
+    attribute uint32_t length;
+
+    /**
+     * True, when output stream has not yet been Close'ed
+     */
+    readonly attribute boolean writeInProgress;
+};
+
+%{C++
+// Factory method
+nsresult
+NS_NewStorageStream(uint32_t segmentSize, uint32_t maxSize, nsIStorageStream **result);
+%}
diff --git a/xpcom/io/nsIStreamBufferAccess.idl b/xpcom/io/nsIStreamBufferAccess.idl
new file mode 100644
index 000000000..c37afd8dc
--- /dev/null
+++ b/xpcom/io/nsIStreamBufferAccess.idl
@@ -0,0 +1,88 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * An interface for access to a buffering stream implementation's underlying
+ * memory buffer.
+ *
+ * Stream implementations that QueryInterface to nsIStreamBufferAccess must
+ * ensure that all buffers are aligned on the most restrictive type size for
+ * the current architecture (e.g., sizeof(double) for RISCy CPUs).  malloc(3)
+ * satisfies this requirement.
+ */
+[scriptable, uuid(ac923b72-ac87-4892-ac7a-ca385d429435)]
+interface nsIStreamBufferAccess : nsISupports
+{
+    /**
+     * Get access to a contiguous, aligned run of bytes in the stream's buffer.
+     * Exactly one successful getBuffer call must occur before a putBuffer call
+     * taking the non-null pointer returned by the successful getBuffer.
+     *
+     * The run of bytes are the next bytes (modulo alignment padding) to read
+     * for an input stream, and the next bytes (modulo alignment padding) to
+     * store before (eventually) writing buffered data to an output stream.
+     * There can be space beyond this run of bytes in the buffer for further
+     * accesses before the fill or flush point is reached.
+     *
+     * @param aLength
+     *    Count of contiguous bytes requested at the address A that satisfies
+     *    (A & aAlignMask) == 0 in the buffer, starting from the current stream
+     *    position, mapped to a buffer address B.  The stream implementation
+     *    must pad from B to A by skipping bytes (if input stream) or storing
+     *    zero bytes (if output stream).
+     *
+     * @param aAlignMask
+     *    Bit-mask computed by subtracting 1 from the power-of-two alignment
+     *    modulus (e.g., 3 or sizeof(uint32_t)-1 for uint32_t alignment).
+     *
+     * @return
+     *    The aligned pointer to aLength bytes in the buffer, or null if the
+     *    buffer has no room for aLength bytes starting at the next address A
+     *    after the current position that satisfies (A & aAlignMask) == 0.
+     */
+    [notxpcom,noscript] charPtr getBuffer(in uint32_t aLength, in uint32_t aAlignMask);
+
+    /**
+     * Relinquish access to the stream's buffer, filling if at end of an input
+     * buffer, flushing if completing an output buffer.  After a getBuffer call
+     * that returns non-null, putBuffer must be called.
+     *
+     * @param aBuffer
+     *    A non-null pointer returned by getBuffer on the same stream buffer
+     *    access object.
+     *
+     * @param aLength
+     *    The same count of contiguous bytes passed to the getBuffer call that
+     *    returned aBuffer.
+     */
+    [notxpcom,noscript] void putBuffer(in charPtr aBuffer, in uint32_t aLength);
+
+    /**
+     * Disable and enable buffering on the stream implementing this interface.
+     * DisableBuffering flushes an output stream's buffer, and invalidates an
+     * input stream's buffer.
+     */
+    void disableBuffering();
+    void enableBuffering();
+
+    /**
+     * The underlying, unbuffered input or output stream.
+     */
+    readonly attribute nsISupports unbufferedStream;
+};
+
+%{C++
+
+/**
+ * These macros get and put a buffer given either an sba parameter that may
+ * point to an object implementing nsIStreamBufferAccess, nsIObjectInputStream,
+ * or nsIObjectOutputStream.
+ */
+#define NS_GET_BUFFER(sba,n,a)  ((sba)->GetBuffer(n, a))
+#define NS_PUT_BUFFER(sba,p,n)  ((sba)->PutBuffer(p, n))
+
+%}
diff --git a/xpcom/io/nsIStringStream.idl b/xpcom/io/nsIStringStream.idl
new file mode 100644
index 000000000..d43200382
--- /dev/null
+++ b/xpcom/io/nsIStringStream.idl
@@ -0,0 +1,66 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIInputStream.idl"
+
+%{C++
+#include "mozilla/MemoryReporting.h"
+%}
+
+native MallocSizeOf(mozilla::MallocSizeOf);
+
+/**
+ * nsIStringInputStream
+ *
+ * Provides scriptable and specialized C++-only methods for initializing a
+ * nsIInputStream implementation with a simple character array.
+ */
+[scriptable, builtinclass, uuid(450cd2d4-f0fd-424d-b365-b1251f80fd53)]
+interface nsIStringInputStream : nsIInputStream
+{
+    /**
+     * SetData - assign data to the input stream (copied on assignment).
+     *
+     * @param data    - stream data
+     * @param dataLen - stream data length (-1 if length should be computed)
+     *
+     * NOTE: C++ code should consider using AdoptData or ShareData to avoid
+     * making an extra copy of the stream data.
+     *
+     * NOTE: For JS callers, the given data must not contain null characters
+     * (other than a null terminator) because a null character in the middle of
+     * the data string will be seen as a terminator when the data is converted
+     * from a JS string to a C++ character array.
+     */
+    void setData(in string data, in long dataLen);
+
+    /**
+     * NOTE: the following methods are designed to give C++ code added control
+     * over the ownership and lifetime of the stream data.  Use with care :-)
+     */
+
+    /**
+     * AdoptData - assign data to the input stream.  the input stream takes
+     * ownership of the given data buffer and will free it when
+     * the input stream is destroyed.
+     *
+     * @param data      - stream data
+     * @param dataLen   - stream data length (-1 if length should be computed)
+     */
+    [noscript] void adoptData(in charPtr data, in long dataLen);
+
+    /**
+     * ShareData - assign data to the input stream.  the input stream references
+     * the given data buffer until the input stream is destroyed.  the given
+     * data buffer must outlive the input stream.
+     *
+     * @param data      - stream data
+     * @param dataLen   - stream data length (-1 if length should be computed)
+     */
+    [noscript] void shareData(in string data, in long dataLen);
+
+    [noscript, notxpcom]
+    size_t SizeOfIncludingThis(in MallocSizeOf aMallocSizeOf);
+};
diff --git a/xpcom/io/nsIUnicharInputStream.idl b/xpcom/io/nsIUnicharInputStream.idl
new file mode 100644
index 000000000..8d0459fed
--- /dev/null
+++ b/xpcom/io/nsIUnicharInputStream.idl
@@ -0,0 +1,95 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIUnicharInputStream;
+interface nsIInputStream;
+
+%{C++
+/**
+ * The signature of the writer function passed to ReadSegments. This
+ * is the "consumer" of data that gets read from the stream's buffer.
+ *
+ * @param aInStream stream being read
+ * @param aClosure opaque parameter passed to ReadSegments
+ * @param aFromSegment pointer to memory owned by the input stream
+ * @param aToOffset amount already read (since ReadSegments was called)
+ * @param aCount length of fromSegment
+ * @param aWriteCount number of bytes read
+ *
+ * Implementers should return the following:
+ *
+ * @throws <any-error> if not interested in consuming any data
+ *
+ * Errors are never passed to the caller of ReadSegments.
+ *
+ * NOTE: returning NS_OK and (*aWriteCount = 0) has undefined behavior.
+ */
+typedef nsresult (*nsWriteUnicharSegmentFun)(nsIUnicharInputStream *aInStream,
+                                             void *aClosure,
+                                             const char16_t *aFromSegment,
+                                             uint32_t aToOffset,
+                                             uint32_t aCount,
+                                             uint32_t *aWriteCount);
+%}
+native nsWriteUnicharSegmentFun(nsWriteUnicharSegmentFun);
+
+/**
+ * Abstract unicode character input stream
+ * @see nsIInputStream
+ */
+[scriptable, uuid(d5e3bd80-6723-4b92-b0c9-22f6162fd94f)]
+interface nsIUnicharInputStream : nsISupports {
+  /**
+   * Reads into a caller-provided character array.
+   *
+   * @return The number of characters that were successfully read. May be less
+   *         than aCount, even if there is more data in the input stream.
+   *         A return value of 0 means EOF.
+   *
+   * @note To read more than 2^32 characters, call this method multiple times.
+   */
+  [noscript] unsigned long read([array, size_is(aCount)] in char16_t aBuf,
+                                in unsigned long aCount);
+
+  /**
+   * Low-level read method that has access to the stream's underlying buffer.
+   * The writer function may be called multiple times for segmented buffers.
+   * ReadSegments is expected to keep calling the writer until either there is
+   * nothing left to read or the writer returns an error.  ReadSegments should
+   * not call the writer with zero characters to consume.
+   *
+   * @param aWriter the "consumer" of the data to be read
+   * @param aClosure opaque parameter passed to writer 
+   * @param aCount the maximum number of characters to be read
+   *
+   * @return number of characters read (may be less than aCount)
+   * @return 0 if reached end of file (or if aWriter refused to consume data)
+   *
+   * @throws NS_BASE_STREAM_WOULD_BLOCK if reading from the input stream would
+   *   block the calling thread (non-blocking mode only)
+   * @throws <other-error> on failure
+   *
+   * NOTE: this function may be unimplemented if a stream has no underlying
+   * buffer
+   */
+  [noscript] unsigned long readSegments(in nsWriteUnicharSegmentFun aWriter,
+                                        in voidPtr aClosure,
+                                        in unsigned long aCount);
+
+  /**
+   * Read into a string object.
+   * @param aCount The number of characters that should be read
+   * @return The number of characters that were read.
+   */
+  unsigned long readString(in unsigned long aCount, out AString aString);
+
+ /**
+  * Close the stream and free associated resources. This also closes the
+  * underlying stream, if any.
+  */
+  void close();
+};
diff --git a/xpcom/io/nsIUnicharLineInputStream.idl b/xpcom/io/nsIUnicharLineInputStream.idl
new file mode 100644
index 000000000..34a67f099
--- /dev/null
+++ b/xpcom/io/nsIUnicharLineInputStream.idl
@@ -0,0 +1,26 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+[scriptable, uuid(67f42475-ba80-40f8-ac0b-649c89230184)]
+interface nsIUnicharLineInputStream : nsISupports
+{
+  /**
+   * Read a single line from the stream, where a line is a 
+   * possibly zero length sequence of characters terminated by a
+   * CR, LF, CRLF, LFCR, or eof.
+   * The line terminator is not returned.
+   * @retval false
+   *         End of file. This line is the last line of the file
+   *         (aLine is valid).
+   * @retval true
+   *         The file contains further lines.
+   * @note Do not mix readLine with other read functions.
+   *       Doing so can cause various problems and is not supported.
+   */
+  boolean readLine(out AString aLine);
+};
diff --git a/xpcom/io/nsIUnicharOutputStream.idl b/xpcom/io/nsIUnicharOutputStream.idl
new file mode 100644
index 000000000..599224dd0
--- /dev/null
+++ b/xpcom/io/nsIUnicharOutputStream.idl
@@ -0,0 +1,47 @@
+/* vim:set expandtab ts=4 sw=4 sts=4 cin: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * An interface that allows writing unicode data.
+ */
+[scriptable, uuid(2d00b1bb-8b21-4a63-bcc6-7213f513ac2e)]
+interface nsIUnicharOutputStream : nsISupports
+{
+    /**
+     * Write a single character to the stream. When writing many characters,
+     * prefer the string-taking write method.
+     *
+     * @retval true The character was written successfully
+     * @retval false Not all bytes of the character could be written.
+     */
+    boolean write(in unsigned long aCount,
+                  [const, array, size_is(aCount)] in char16_t c);
+
+    /**
+     * Write a string to the stream.
+     *
+     * @retval true The string was written successfully
+     * @retval false Not all bytes of the string could be written.
+     */
+    boolean writeString(in AString str);
+
+    /**
+     * Flush the stream. This finishes the conversion and writes any bytes that
+     * finish the current byte sequence.
+     *
+     * It does NOT flush the underlying stream.
+     *
+     * @see nsIUnicodeEncoder::Finish
+     */
+    void flush();
+
+    /**
+     * Close the stream and free associated resources. This also closes the
+     * underlying stream.
+     */
+    void close();
+};
diff --git a/xpcom/io/nsInputStreamTee.cpp b/xpcom/io/nsInputStreamTee.cpp
new file mode 100644
index 000000000..8f01cb87e
--- /dev/null
+++ b/xpcom/io/nsInputStreamTee.cpp
@@ -0,0 +1,366 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdlib.h>
+#include "mozilla/Logging.h"
+
+#include "mozilla/Mutex.h"
+#include "mozilla/Attributes.h"
+#include "nsIInputStreamTee.h"
+#include "nsIInputStream.h"
+#include "nsIOutputStream.h"
+#include "nsCOMPtr.h"
+#include "nsAutoPtr.h"
+#include "nsIEventTarget.h"
+#include "nsThreadUtils.h"
+
+using namespace mozilla;
+
+#ifdef LOG
+#undef LOG
+#endif
+
+static LazyLogModule sTeeLog("nsInputStreamTee");
+#define LOG(args) MOZ_LOG(sTeeLog, mozilla::LogLevel::Debug, args)
+
+class nsInputStreamTee final : public nsIInputStreamTee
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIINPUTSTREAM
+  NS_DECL_NSIINPUTSTREAMTEE
+
+  nsInputStreamTee();
+  bool SinkIsValid();
+  void InvalidateSink();
+
+private:
+  ~nsInputStreamTee()
+  {
+  }
+
+  nsresult TeeSegment(const char* aBuf, uint32_t aCount);
+
+  static nsresult WriteSegmentFun(nsIInputStream*, void*, const char*,
+                                  uint32_t, uint32_t, uint32_t*);
+
+private:
+  nsCOMPtr<nsIInputStream>  mSource;
+  nsCOMPtr<nsIOutputStream> mSink;
+  nsCOMPtr<nsIEventTarget>  mEventTarget;
+  nsWriteSegmentFun         mWriter;  // for implementing ReadSegments
+  void*                     mClosure; // for implementing ReadSegments
+  nsAutoPtr<Mutex>          mLock; // synchronize access to mSinkIsValid
+  bool                      mSinkIsValid; // False if TeeWriteEvent fails
+};
+
+class nsInputStreamTeeWriteEvent : public Runnable
+{
+public:
+  // aTee's lock is held across construction of this object
+  nsInputStreamTeeWriteEvent(const char* aBuf, uint32_t aCount,
+                             nsIOutputStream* aSink, nsInputStreamTee* aTee)
+  {
+    // copy the buffer - will be free'd by dtor
+    mBuf = (char*)malloc(aCount);
+    if (mBuf) {
+      memcpy(mBuf, (char*)aBuf, aCount);
+    }
+    mCount = aCount;
+    mSink = aSink;
+    bool isNonBlocking;
+    mSink->IsNonBlocking(&isNonBlocking);
+    NS_ASSERTION(isNonBlocking == false, "mSink is nonblocking");
+    mTee = aTee;
+  }
+
+  NS_IMETHOD Run() override
+  {
+    if (!mBuf) {
+      NS_WARNING("nsInputStreamTeeWriteEvent::Run() "
+                 "memory not allocated\n");
+      return NS_OK;
+    }
+    MOZ_ASSERT(mSink, "mSink is null!");
+
+    //  The output stream could have been invalidated between when
+    //  this event was dispatched and now, so check before writing.
+    if (!mTee->SinkIsValid()) {
+      return NS_OK;
+    }
+
+    LOG(("nsInputStreamTeeWriteEvent::Run() [%p]"
+         "will write %u bytes to %p\n",
+         this, mCount, mSink.get()));
+
+    uint32_t totalBytesWritten = 0;
+    while (mCount) {
+      nsresult rv;
+      uint32_t bytesWritten = 0;
+      rv = mSink->Write(mBuf + totalBytesWritten, mCount, &bytesWritten);
+      if (NS_FAILED(rv)) {
+        LOG(("nsInputStreamTeeWriteEvent::Run[%p] error %x in writing",
+             this, rv));
+        mTee->InvalidateSink();
+        break;
+      }
+      totalBytesWritten += bytesWritten;
+      NS_ASSERTION(bytesWritten <= mCount, "wrote too much");
+      mCount -= bytesWritten;
+    }
+    return NS_OK;
+  }
+
+protected:
+  virtual ~nsInputStreamTeeWriteEvent()
+  {
+    if (mBuf) {
+      free(mBuf);
+    }
+    mBuf = nullptr;
+  }
+
+private:
+  char* mBuf;
+  uint32_t mCount;
+  nsCOMPtr<nsIOutputStream> mSink;
+  // back pointer to the tee that created this runnable
+  RefPtr<nsInputStreamTee> mTee;
+};
+
+nsInputStreamTee::nsInputStreamTee(): mLock(nullptr)
+  , mSinkIsValid(true)
+{
+}
+
+bool
+nsInputStreamTee::SinkIsValid()
+{
+  MutexAutoLock lock(*mLock);
+  return mSinkIsValid;
+}
+
+void
+nsInputStreamTee::InvalidateSink()
+{
+  MutexAutoLock lock(*mLock);
+  mSinkIsValid = false;
+}
+
+nsresult
+nsInputStreamTee::TeeSegment(const char* aBuf, uint32_t aCount)
+{
+  if (!mSink) {
+    return NS_OK;  // nothing to do
+  }
+  if (mLock) { // asynchronous case
+    NS_ASSERTION(mEventTarget, "mEventTarget is null, mLock is not null.");
+    if (!SinkIsValid()) {
+      return NS_OK; // nothing to do
+    }
+    nsCOMPtr<nsIRunnable> event =
+      new nsInputStreamTeeWriteEvent(aBuf, aCount, mSink, this);
+    LOG(("nsInputStreamTee::TeeSegment [%p] dispatching write %u bytes\n",
+         this, aCount));
+    return mEventTarget->Dispatch(event, NS_DISPATCH_NORMAL);
+  } else { // synchronous case
+    NS_ASSERTION(!mEventTarget, "mEventTarget is not null, mLock is null.");
+    nsresult rv;
+    uint32_t totalBytesWritten = 0;
+    while (aCount) {
+      uint32_t bytesWritten = 0;
+      rv = mSink->Write(aBuf + totalBytesWritten, aCount, &bytesWritten);
+      if (NS_FAILED(rv)) {
+        // ok, this is not a fatal error... just drop our reference to mSink
+        // and continue on as if nothing happened.
+        NS_WARNING("Write failed (non-fatal)");
+        // catch possible misuse of the input stream tee
+        NS_ASSERTION(rv != NS_BASE_STREAM_WOULD_BLOCK, "sink must be a blocking stream");
+        mSink = nullptr;
+        break;
+      }
+      totalBytesWritten += bytesWritten;
+      NS_ASSERTION(bytesWritten <= aCount, "wrote too much");
+      aCount -= bytesWritten;
+    }
+    return NS_OK;
+  }
+}
+
+nsresult
+nsInputStreamTee::WriteSegmentFun(nsIInputStream* aIn, void* aClosure,
+                                  const char* aFromSegment, uint32_t aOffset,
+                                  uint32_t aCount, uint32_t* aWriteCount)
+{
+  nsInputStreamTee* tee = reinterpret_cast<nsInputStreamTee*>(aClosure);
+  nsresult rv = tee->mWriter(aIn, tee->mClosure, aFromSegment, aOffset,
+                             aCount, aWriteCount);
+  if (NS_FAILED(rv) || (*aWriteCount == 0)) {
+    NS_ASSERTION((NS_FAILED(rv) ? (*aWriteCount == 0) : true),
+                 "writer returned an error with non-zero writeCount");
+    return rv;
+  }
+
+  return tee->TeeSegment(aFromSegment, *aWriteCount);
+}
+
+NS_IMPL_ISUPPORTS(nsInputStreamTee,
+                  nsIInputStreamTee,
+                  nsIInputStream)
+NS_IMETHODIMP
+nsInputStreamTee::Close()
+{
+  if (NS_WARN_IF(!mSource)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  nsresult rv = mSource->Close();
+  mSource = nullptr;
+  mSink = nullptr;
+  return rv;
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::Available(uint64_t* aAvail)
+{
+  if (NS_WARN_IF(!mSource)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return mSource->Available(aAvail);
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::Read(char* aBuf, uint32_t aCount, uint32_t* aBytesRead)
+{
+  if (NS_WARN_IF(!mSource)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  nsresult rv = mSource->Read(aBuf, aCount, aBytesRead);
+  if (NS_FAILED(rv) || (*aBytesRead == 0)) {
+    return rv;
+  }
+
+  return TeeSegment(aBuf, *aBytesRead);
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::ReadSegments(nsWriteSegmentFun aWriter,
+                               void* aClosure,
+                               uint32_t aCount,
+                               uint32_t* aBytesRead)
+{
+  if (NS_WARN_IF(!mSource)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  mWriter = aWriter;
+  mClosure = aClosure;
+
+  return mSource->ReadSegments(WriteSegmentFun, this, aCount, aBytesRead);
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::IsNonBlocking(bool* aResult)
+{
+  if (NS_WARN_IF(!mSource)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return mSource->IsNonBlocking(aResult);
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::SetSource(nsIInputStream* aSource)
+{
+  mSource = aSource;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::GetSource(nsIInputStream** aSource)
+{
+  NS_IF_ADDREF(*aSource = mSource);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::SetSink(nsIOutputStream* aSink)
+{
+#ifdef DEBUG
+  if (aSink) {
+    bool nonBlocking;
+    nsresult rv = aSink->IsNonBlocking(&nonBlocking);
+    if (NS_FAILED(rv) || nonBlocking) {
+      NS_ERROR("aSink should be a blocking stream");
+    }
+  }
+#endif
+  mSink = aSink;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::GetSink(nsIOutputStream** aSink)
+{
+  NS_IF_ADDREF(*aSink = mSink);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::SetEventTarget(nsIEventTarget* aEventTarget)
+{
+  mEventTarget = aEventTarget;
+  if (mEventTarget) {
+    // Only need synchronization if this is an async tee
+    mLock = new Mutex("nsInputStreamTee.mLock");
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsInputStreamTee::GetEventTarget(nsIEventTarget** aEventTarget)
+{
+  NS_IF_ADDREF(*aEventTarget = mEventTarget);
+  return NS_OK;
+}
+
+
+nsresult
+NS_NewInputStreamTeeAsync(nsIInputStream** aResult,
+                          nsIInputStream* aSource,
+                          nsIOutputStream* aSink,
+                          nsIEventTarget* aEventTarget)
+{
+  nsresult rv;
+
+  nsCOMPtr<nsIInputStreamTee> tee = new nsInputStreamTee();
+  rv = tee->SetSource(aSource);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  rv = tee->SetSink(aSink);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  rv = tee->SetEventTarget(aEventTarget);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  tee.forget(aResult);
+  return rv;
+}
+
+nsresult
+NS_NewInputStreamTee(nsIInputStream** aResult,
+                     nsIInputStream* aSource,
+                     nsIOutputStream* aSink)
+{
+  return NS_NewInputStreamTeeAsync(aResult, aSource, aSink, nullptr);
+}
+
+#undef LOG
diff --git a/xpcom/io/nsLinebreakConverter.cpp b/xpcom/io/nsLinebreakConverter.cpp
new file mode 100644
index 000000000..007685a6a
--- /dev/null
+++ b/xpcom/io/nsLinebreakConverter.cpp
@@ -0,0 +1,488 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsLinebreakConverter.h"
+
+#include "nsMemory.h"
+#include "nsCRT.h"
+
+
+/*----------------------------------------------------------------------------
+  GetLinebreakString
+
+  Could make this inline
+----------------------------------------------------------------------------*/
+static const char*
+GetLinebreakString(nsLinebreakConverter::ELinebreakType aBreakType)
+{
+  static const char* const sLinebreaks[] = {
+    "",             // any
+    NS_LINEBREAK,   // platform
+    LFSTR,          // content
+    CRLF,           // net
+    CRSTR,          // Mac
+    LFSTR,          // Unix
+    CRLF,           // Windows
+    " ",            // space
+    nullptr
+  };
+
+  return sLinebreaks[aBreakType];
+}
+
+
+/*----------------------------------------------------------------------------
+  AppendLinebreak
+
+  Wee inline method to append a line break. Modifies ioDest.
+----------------------------------------------------------------------------*/
+template<class T>
+void
+AppendLinebreak(T*& aIoDest, const char* aLineBreakStr)
+{
+  *aIoDest++ = *aLineBreakStr;
+
+  if (aLineBreakStr[1]) {
+    *aIoDest++ = aLineBreakStr[1];
+  }
+}
+
+/*----------------------------------------------------------------------------
+  CountChars
+
+  Counts occurrences of breakStr in aSrc
+----------------------------------------------------------------------------*/
+template<class T>
+int32_t
+CountLinebreaks(const T* aSrc, int32_t aInLen, const char* aBreakStr)
+{
+  const T* src = aSrc;
+  const T* srcEnd = aSrc + aInLen;
+  int32_t theCount = 0;
+
+  while (src < srcEnd) {
+    if (*src == *aBreakStr) {
+      src++;
+
+      if (aBreakStr[1]) {
+        if (src < srcEnd && *src == aBreakStr[1]) {
+          src++;
+          theCount++;
+        }
+      } else {
+        theCount++;
+      }
+    } else {
+      src++;
+    }
+  }
+
+  return theCount;
+}
+
+
+/*----------------------------------------------------------------------------
+  ConvertBreaks
+
+  ioLen *includes* a terminating null, if any
+----------------------------------------------------------------------------*/
+template<class T>
+static T*
+ConvertBreaks(const T* aInSrc, int32_t& aIoLen, const char* aSrcBreak,
+              const char* aDestBreak)
+{
+  NS_ASSERTION(aInSrc && aSrcBreak && aDestBreak, "Got a null string");
+
+  T* resultString = nullptr;
+
+  // handle the no conversion case
+  if (nsCRT::strcmp(aSrcBreak, aDestBreak) == 0) {
+    resultString = (T*)malloc(sizeof(T) * aIoLen);
+    if (!resultString) {
+      return nullptr;
+    }
+    memcpy(resultString, aInSrc, sizeof(T) * aIoLen); // includes the null, if any
+    return resultString;
+  }
+
+  int32_t srcBreakLen = strlen(aSrcBreak);
+  int32_t destBreakLen = strlen(aDestBreak);
+
+  // handle the easy case, where the string length does not change, and the
+  // breaks are only 1 char long, i.e. CR <-> LF
+  if (srcBreakLen == destBreakLen && srcBreakLen == 1) {
+    resultString = (T*)malloc(sizeof(T) * aIoLen);
+    if (!resultString) {
+      return nullptr;
+    }
+
+    const T* src = aInSrc;
+    const T* srcEnd = aInSrc + aIoLen;  // includes null, if any
+    T* dst = resultString;
+
+    char srcBreakChar = *aSrcBreak;  // we know it's one char long already
+    char dstBreakChar = *aDestBreak;
+
+    while (src < srcEnd) {
+      if (*src == srcBreakChar) {
+        *dst++ = dstBreakChar;
+        src++;
+      } else {
+        *dst++ = *src++;
+      }
+    }
+
+    // aIoLen does not change
+  } else {
+    // src and dest termination is different length. Do it a slower way.
+
+    // count linebreaks in src. Assumes that chars in 2-char linebreaks are unique.
+    int32_t numLinebreaks = CountLinebreaks(aInSrc, aIoLen, aSrcBreak);
+
+    int32_t newBufLen =
+      aIoLen - (numLinebreaks * srcBreakLen) + (numLinebreaks * destBreakLen);
+    resultString = (T*)malloc(sizeof(T) * newBufLen);
+    if (!resultString) {
+      return nullptr;
+    }
+
+    const T* src = aInSrc;
+    const T* srcEnd = aInSrc + aIoLen;  // includes null, if any
+    T* dst = resultString;
+
+    while (src < srcEnd) {
+      if (*src == *aSrcBreak) {
+        *dst++ = *aDestBreak;
+        if (aDestBreak[1]) {
+          *dst++ = aDestBreak[1];
+        }
+
+        src++;
+        if (src < srcEnd && aSrcBreak[1] && *src == aSrcBreak[1]) {
+          src++;
+        }
+      } else {
+        *dst++ = *src++;
+      }
+    }
+
+    aIoLen = newBufLen;
+  }
+
+  return resultString;
+}
+
+
+/*----------------------------------------------------------------------------
+  ConvertBreaksInSitu
+
+  Convert breaks in situ. Can only do this if the linebreak length
+  does not change.
+----------------------------------------------------------------------------*/
+template<class T>
+static void
+ConvertBreaksInSitu(T* aInSrc, int32_t aInLen, char aSrcBreak, char aDestBreak)
+{
+  T* src = aInSrc;
+  T* srcEnd = aInSrc + aInLen;
+
+  while (src < srcEnd) {
+    if (*src == aSrcBreak) {
+      *src = aDestBreak;
+    }
+
+    src++;
+  }
+}
+
+
+/*----------------------------------------------------------------------------
+  ConvertUnknownBreaks
+
+  Convert unknown line breaks to the specified break.
+
+  This will convert CRLF pairs to one break, and single CR or LF to a break.
+----------------------------------------------------------------------------*/
+template<class T>
+static T*
+ConvertUnknownBreaks(const T* aInSrc, int32_t& aIoLen, const char* aDestBreak)
+{
+  const T* src = aInSrc;
+  const T* srcEnd = aInSrc + aIoLen;  // includes null, if any
+
+  int32_t destBreakLen = strlen(aDestBreak);
+  int32_t finalLen = 0;
+
+  while (src < srcEnd) {
+    if (*src == nsCRT::CR) {
+      if (src < srcEnd && src[1] == nsCRT::LF) {
+        // CRLF
+        finalLen += destBreakLen;
+        src++;
+      } else {
+        // Lone CR
+        finalLen += destBreakLen;
+      }
+    } else if (*src == nsCRT::LF) {
+      // Lone LF
+      finalLen += destBreakLen;
+    } else {
+      finalLen++;
+    }
+    src++;
+  }
+
+  T* resultString = (T*)malloc(sizeof(T) * finalLen);
+  if (!resultString) {
+    return nullptr;
+  }
+
+  src = aInSrc;
+  srcEnd = aInSrc + aIoLen;  // includes null, if any
+
+  T* dst = resultString;
+
+  while (src < srcEnd) {
+    if (*src == nsCRT::CR) {
+      if (src < srcEnd && src[1] == nsCRT::LF) {
+        // CRLF
+        AppendLinebreak(dst, aDestBreak);
+        src++;
+      } else {
+        // Lone CR
+        AppendLinebreak(dst, aDestBreak);
+      }
+    } else if (*src == nsCRT::LF) {
+      // Lone LF
+      AppendLinebreak(dst, aDestBreak);
+    } else {
+      *dst++ = *src;
+    }
+    src++;
+  }
+
+  aIoLen = finalLen;
+  return resultString;
+}
+
+
+/*----------------------------------------------------------------------------
+  ConvertLineBreaks
+
+----------------------------------------------------------------------------*/
+char*
+nsLinebreakConverter::ConvertLineBreaks(const char* aSrc,
+                                        ELinebreakType aSrcBreaks,
+                                        ELinebreakType aDestBreaks,
+                                        int32_t aSrcLen, int32_t* aOutLen)
+{
+  NS_ASSERTION(aDestBreaks != eLinebreakAny &&
+               aSrcBreaks != eLinebreakSpace, "Invalid parameter");
+  if (!aSrc) {
+    return nullptr;
+  }
+
+  int32_t sourceLen = (aSrcLen == kIgnoreLen) ? strlen(aSrc) + 1 : aSrcLen;
+
+  char* resultString;
+  if (aSrcBreaks == eLinebreakAny) {
+    resultString = ConvertUnknownBreaks(aSrc, sourceLen,
+                                        GetLinebreakString(aDestBreaks));
+  } else
+    resultString = ConvertBreaks(aSrc, sourceLen,
+                                 GetLinebreakString(aSrcBreaks),
+                                 GetLinebreakString(aDestBreaks));
+
+  if (aOutLen) {
+    *aOutLen = sourceLen;
+  }
+  return resultString;
+}
+
+
+/*----------------------------------------------------------------------------
+  ConvertLineBreaksInSitu
+
+----------------------------------------------------------------------------*/
+nsresult
+nsLinebreakConverter::ConvertLineBreaksInSitu(char** aIoBuffer,
+                                              ELinebreakType aSrcBreaks,
+                                              ELinebreakType aDestBreaks,
+                                              int32_t aSrcLen, int32_t* aOutLen)
+{
+  NS_ASSERTION(aIoBuffer && *aIoBuffer, "Null pointer passed");
+  if (!aIoBuffer || !*aIoBuffer) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  NS_ASSERTION(aDestBreaks != eLinebreakAny &&
+               aSrcBreaks != eLinebreakSpace, "Invalid parameter");
+
+  int32_t sourceLen = (aSrcLen == kIgnoreLen) ? strlen(*aIoBuffer) + 1 : aSrcLen;
+
+  // can we convert in-place?
+  const char* srcBreaks = GetLinebreakString(aSrcBreaks);
+  const char* dstBreaks = GetLinebreakString(aDestBreaks);
+
+  if (aSrcBreaks != eLinebreakAny &&
+      strlen(srcBreaks) == 1 &&
+      strlen(dstBreaks) == 1) {
+    ConvertBreaksInSitu(*aIoBuffer, sourceLen, *srcBreaks, *dstBreaks);
+    if (aOutLen) {
+      *aOutLen = sourceLen;
+    }
+  } else {
+    char* destBuffer;
+
+    if (aSrcBreaks == eLinebreakAny) {
+      destBuffer = ConvertUnknownBreaks(*aIoBuffer, sourceLen, dstBreaks);
+    } else {
+      destBuffer = ConvertBreaks(*aIoBuffer, sourceLen, srcBreaks, dstBreaks);
+    }
+
+    if (!destBuffer) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    *aIoBuffer = destBuffer;
+    if (aOutLen) {
+      *aOutLen = sourceLen;
+    }
+  }
+
+  return NS_OK;
+}
+
+
+/*----------------------------------------------------------------------------
+  ConvertUnicharLineBreaks
+
+----------------------------------------------------------------------------*/
+char16_t*
+nsLinebreakConverter::ConvertUnicharLineBreaks(const char16_t* aSrc,
+                                               ELinebreakType aSrcBreaks,
+                                               ELinebreakType aDestBreaks,
+                                               int32_t aSrcLen,
+                                               int32_t* aOutLen)
+{
+  NS_ASSERTION(aDestBreaks != eLinebreakAny &&
+               aSrcBreaks != eLinebreakSpace, "Invalid parameter");
+  if (!aSrc) {
+    return nullptr;
+  }
+
+  int32_t bufLen = (aSrcLen == kIgnoreLen) ? NS_strlen(aSrc) + 1 : aSrcLen;
+
+  char16_t* resultString;
+  if (aSrcBreaks == eLinebreakAny) {
+    resultString = ConvertUnknownBreaks(aSrc, bufLen,
+                                        GetLinebreakString(aDestBreaks));
+  } else
+    resultString = ConvertBreaks(aSrc, bufLen, GetLinebreakString(aSrcBreaks),
+                                 GetLinebreakString(aDestBreaks));
+
+  if (aOutLen) {
+    *aOutLen = bufLen;
+  }
+  return resultString;
+}
+
+
+/*----------------------------------------------------------------------------
+  ConvertStringLineBreaks
+
+----------------------------------------------------------------------------*/
+nsresult
+nsLinebreakConverter::ConvertUnicharLineBreaksInSitu(
+    char16_t** aIoBuffer, ELinebreakType aSrcBreaks, ELinebreakType aDestBreaks,
+    int32_t aSrcLen, int32_t* aOutLen)
+{
+  NS_ASSERTION(aIoBuffer && *aIoBuffer, "Null pointer passed");
+  if (!aIoBuffer || !*aIoBuffer) {
+    return NS_ERROR_NULL_POINTER;
+  }
+  NS_ASSERTION(aDestBreaks != eLinebreakAny &&
+               aSrcBreaks != eLinebreakSpace, "Invalid parameter");
+
+  int32_t sourceLen =
+    (aSrcLen == kIgnoreLen) ? NS_strlen(*aIoBuffer) + 1 : aSrcLen;
+
+  // can we convert in-place?
+  const char* srcBreaks = GetLinebreakString(aSrcBreaks);
+  const char* dstBreaks = GetLinebreakString(aDestBreaks);
+
+  if ((aSrcBreaks != eLinebreakAny) &&
+      (strlen(srcBreaks) == 1) &&
+      (strlen(dstBreaks) == 1)) {
+    ConvertBreaksInSitu(*aIoBuffer, sourceLen, *srcBreaks, *dstBreaks);
+    if (aOutLen) {
+      *aOutLen = sourceLen;
+    }
+  } else {
+    char16_t* destBuffer;
+
+    if (aSrcBreaks == eLinebreakAny) {
+      destBuffer = ConvertUnknownBreaks(*aIoBuffer, sourceLen, dstBreaks);
+    } else {
+      destBuffer = ConvertBreaks(*aIoBuffer, sourceLen, srcBreaks, dstBreaks);
+    }
+
+    if (!destBuffer) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    *aIoBuffer = destBuffer;
+    if (aOutLen) {
+      *aOutLen = sourceLen;
+    }
+  }
+
+  return NS_OK;
+}
+
+/*----------------------------------------------------------------------------
+  ConvertStringLineBreaks
+
+----------------------------------------------------------------------------*/
+nsresult
+nsLinebreakConverter::ConvertStringLineBreaks(nsString& aIoString,
+                                              ELinebreakType aSrcBreaks,
+                                              ELinebreakType aDestBreaks)
+{
+
+  NS_ASSERTION(aDestBreaks != eLinebreakAny &&
+               aSrcBreaks != eLinebreakSpace, "Invalid parameter");
+
+  // nothing to do
+  if (aIoString.IsEmpty()) {
+    return NS_OK;
+  }
+
+  nsresult rv;
+
+  // remember the old buffer in case
+  // we blow it away later
+  nsString::char_iterator stringBuf;
+  if (!aIoString.BeginWriting(stringBuf, fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  int32_t    newLen;
+
+  rv = ConvertUnicharLineBreaksInSitu(&stringBuf,
+                                      aSrcBreaks, aDestBreaks,
+                                      aIoString.Length() + 1, &newLen);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (stringBuf != aIoString.get()) {
+    aIoString.Adopt(stringBuf, newLen - 1);
+  }
+
+  return NS_OK;
+}
+
+
+
diff --git a/xpcom/io/nsLinebreakConverter.h b/xpcom/io/nsLinebreakConverter.h
new file mode 100644
index 000000000..a1678ef2d
--- /dev/null
+++ b/xpcom/io/nsLinebreakConverter.h
@@ -0,0 +1,131 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsLinebreakConverter_h_
+#define nsLinebreakConverter_h_
+
+#include "nscore.h"
+#include "nsString.h"
+
+// utility class for converting between different line breaks.
+
+class nsLinebreakConverter
+{
+public:
+
+  // Note: enum must match char* array in GetLinebreakString
+  typedef enum {
+    eLinebreakAny,          // any kind of linebreak (i.e. "don't care" source)
+
+    eLinebreakPlatform,     // platform linebreak
+    eLinebreakContent,      // Content model linebreak (LF)
+    eLinebreakNet,          // Form submission linebreak (CRLF)
+
+    eLinebreakMac,          // CR
+    eLinebreakUnix,         // LF
+    eLinebreakWindows,      // CRLF
+
+    eLinebreakSpace         // space characters. Only valid as destination type
+
+  } ELinebreakType;
+
+  enum {
+    kIgnoreLen = -1
+  };
+
+  /* ConvertLineBreaks
+   * Convert line breaks in the supplied string, allocating and returning
+   * a new buffer. Returns nullptr on failure.
+   * @param aSrc: the source string. if aSrcLen == kIgnoreLen this string is assumed
+   *              to be null terminated, otherwise it must be at least aSrcLen long.
+   * @param aSrcBreaks: the line breaks in the source. If unknown, pass eLinebreakAny.
+   *              If known, pass the known value, as this may be more efficient.
+   * @param aDestBreaks: the line breaks you want in the output.
+   * @param aSrcLen: length of the source. If -1, the source is assumed to be a null-
+   *              terminated string.
+   * @param aOutLen: used to return character length of returned buffer, if not null.
+   */
+  static char* ConvertLineBreaks(const char* aSrc,
+                                 ELinebreakType aSrcBreaks, ELinebreakType aDestBreaks,
+                                 int32_t aSrcLen = kIgnoreLen, int32_t* aOutLen = nullptr);
+
+
+  /* ConvertUnicharLineBreaks
+   * Convert line breaks in the supplied string, allocating and returning
+   * a new buffer. Returns nullptr on failure.
+   * @param aSrc: the source string. if aSrcLen == kIgnoreLen this string is assumed
+   *              to be null terminated, otherwise it must be at least aSrcLen long.
+   * @param aSrcBreaks: the line breaks in the source. If unknown, pass eLinebreakAny.
+   *              If known, pass the known value, as this may be more efficient.
+   * @param aDestBreaks: the line breaks you want in the output.
+   * @param aSrcLen: length of the source, in characters. If -1, the source is assumed to be a null-
+   *              terminated string.
+   * @param aOutLen: used to return character length of returned buffer, if not null.
+   */
+  static char16_t* ConvertUnicharLineBreaks(const char16_t* aSrc,
+                                            ELinebreakType aSrcBreaks, ELinebreakType aDestBreaks,
+                                            int32_t aSrcLen = kIgnoreLen, int32_t* aOutLen = nullptr);
+
+
+  /* ConvertStringLineBreaks
+   * Convert line breaks in the supplied string, changing the string buffer (i.e. in-place conversion)
+   * @param ioString: the string to be converted.
+   * @param aSrcBreaks: the line breaks in the source. If unknown, pass eLinebreakAny.
+   *              If known, pass the known value, as this may be more efficient.
+   * @param aDestBreaks: the line breaks you want in the output.
+   * @param aSrcLen: length of the source, in characters. If -1, the source is assumed to be a null-
+   *              terminated string.
+   */
+  static nsresult ConvertStringLineBreaks(nsString& aIoString,
+                                          ELinebreakType aSrcBreaks,
+                                          ELinebreakType aDestBreaks);
+
+
+  /* ConvertLineBreaksInSitu
+   * Convert line breaks in place if possible. NOTE: THIS MAY REALLOCATE THE BUFFER,
+   * BUT IT WON'T FREE THE OLD BUFFER (because it doesn't know how). So be prepared
+   * to keep a copy of the old pointer, and free it if this passes back a new pointer.
+   * ALSO NOTE: DON'T PASS A STATIC STRING POINTER TO THIS FUNCTION.
+   *
+   * @param ioBuffer: the source buffer. if aSrcLen == kIgnoreLen this string is assumed
+   *              to be null terminated, otherwise it must be at least aSrcLen long.
+   * @param aSrcBreaks: the line breaks in the source. If unknown, pass eLinebreakAny.
+   *              If known, pass the known value, as this may be more efficient.
+   * @param aDestBreaks: the line breaks you want in the output.
+   * @param aSrcLen: length of the source. If -1, the source is assumed to be a null-
+   *              terminated string.
+   * @param aOutLen: used to return character length of returned buffer, if not null.
+   */
+  static nsresult ConvertLineBreaksInSitu(char** aIoBuffer,
+                                          ELinebreakType aSrcBreaks,
+                                          ELinebreakType aDestBreaks,
+                                          int32_t aSrcLen = kIgnoreLen,
+                                          int32_t* aOutLen = nullptr);
+
+
+  /* ConvertUnicharLineBreaksInSitu
+   * Convert line breaks in place if possible. NOTE: THIS MAY REALLOCATE THE BUFFER,
+   * BUT IT WON'T FREE THE OLD BUFFER (because it doesn't know how). So be prepared
+   * to keep a copy of the old pointer, and free it if this passes back a new pointer.
+   *
+   * @param ioBuffer: the source buffer. if aSrcLen == kIgnoreLen this string is assumed
+   *              to be null terminated, otherwise it must be at least aSrcLen long.
+   * @param aSrcBreaks: the line breaks in the source. If unknown, pass eLinebreakAny.
+   *              If known, pass the known value, as this may be more efficient.
+   * @param aDestBreaks: the line breaks you want in the output.
+   * @param aSrcLen: length of the source in characters. If -1, the source is assumed to be a null-
+   *              terminated string.
+   * @param aOutLen: used to return character length of returned buffer, if not null.
+   */
+  static nsresult ConvertUnicharLineBreaksInSitu(char16_t** aIoBuffer,
+                                                 ELinebreakType aSrcBreaks,
+                                                 ELinebreakType aDestBreaks,
+                                                 int32_t aSrcLen = kIgnoreLen,
+                                                 int32_t* aOutLen = nullptr);
+
+};
+
+#endif // nsLinebreakConverter_h_
diff --git a/xpcom/io/nsLocalFile.h b/xpcom/io/nsLocalFile.h
new file mode 100644
index 000000000..f7bdb86f7
--- /dev/null
+++ b/xpcom/io/nsLocalFile.h
@@ -0,0 +1,124 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This Original Code has been modified by IBM Corporation. Modifications made by IBM
+ * described herein are Copyright (c) International Business Machines Corporation, 2000.
+ * Modifications to Mozilla code or documentation identified per MPL Section 3.3
+ *
+ * Date             Modified by     Description of modification
+ * 04/20/2000       IBM Corp.      OS/2 build.
+ */
+
+#ifndef _NS_LOCAL_FILE_H_
+#define _NS_LOCAL_FILE_H_
+
+#include "nscore.h"
+
+#define NS_LOCAL_FILE_CID {0x2e23e220, 0x60be, 0x11d3, {0x8c, 0x4a, 0x00, 0x00, 0x64, 0x65, 0x73, 0x74}}
+
+#define NS_DECL_NSLOCALFILE_UNICODE_METHODS                                                      \
+  nsresult AppendUnicode(const char16_t *aNode);                                              \
+  nsresult GetUnicodeLeafName(char16_t **aLeafName);                                          \
+  nsresult SetUnicodeLeafName(const char16_t *aLeafName);                                     \
+  nsresult CopyToUnicode(nsIFile *aNewParentDir, const char16_t *aNewLeafName);               \
+  nsresult CopyToFollowingLinksUnicode(nsIFile *aNewParentDir, const char16_t *aNewLeafName); \
+  nsresult MoveToUnicode(nsIFile *aNewParentDir, const char16_t *aNewLeafName);               \
+  nsresult GetUnicodeTarget(char16_t **aTarget);                                              \
+  nsresult GetUnicodePath(char16_t **aPath);                                                  \
+  nsresult InitWithUnicodePath(const char16_t *aPath);                                        \
+  nsresult AppendRelativeUnicodePath(const char16_t *aRelativePath);
+
+// XPCOMInit needs to know about how we are implemented,
+// so here we will export it.  Other users should not depend
+// on this.
+
+#include <errno.h>
+#include "nsILocalFile.h"
+
+#ifdef XP_WIN
+#include "nsLocalFileWin.h"
+#elif defined(XP_UNIX)
+#include "nsLocalFileUnix.h"
+#else
+#error NOT_IMPLEMENTED
+#endif
+
+#define NSRESULT_FOR_RETURN(ret) (((ret) < 0) ? NSRESULT_FOR_ERRNO() : NS_OK)
+
+inline nsresult
+nsresultForErrno(int aErr)
+{
+  switch (aErr) {
+    case 0:
+      return NS_OK;
+#ifdef EDQUOT
+    case EDQUOT: /* Quota exceeded */
+      // FALLTHROUGH to return NS_ERROR_FILE_DISK_FULL
+#endif
+    case ENOSPC:
+      return NS_ERROR_FILE_DISK_FULL;
+#ifdef EISDIR
+    case EISDIR:    /*      Is a directory. */
+      return NS_ERROR_FILE_IS_DIRECTORY;
+#endif
+    case ENAMETOOLONG:
+      return NS_ERROR_FILE_NAME_TOO_LONG;
+    case ENOEXEC:  /*     Executable file format error. */
+      return NS_ERROR_FILE_EXECUTION_FAILED;
+    case ENOENT:
+      return NS_ERROR_FILE_TARGET_DOES_NOT_EXIST;
+    case ENOTDIR:
+      return NS_ERROR_FILE_DESTINATION_NOT_DIR;
+#ifdef ELOOP
+    case ELOOP:
+      return NS_ERROR_FILE_UNRESOLVABLE_SYMLINK;
+#endif /* ELOOP */
+#ifdef ENOLINK
+    case ENOLINK:
+      return NS_ERROR_FILE_UNRESOLVABLE_SYMLINK;
+#endif /* ENOLINK */
+    case EEXIST:
+      return NS_ERROR_FILE_ALREADY_EXISTS;
+#ifdef EPERM
+    case EPERM:
+#endif /* EPERM */
+    case EACCES:
+      return NS_ERROR_FILE_ACCESS_DENIED;
+#ifdef EROFS
+    case EROFS: /*     Read-only file system. */
+      return NS_ERROR_FILE_READ_ONLY;
+#endif
+    /*
+     * On AIX 4.3, ENOTEMPTY is defined as EEXIST,
+     * so there can't be cases for both without
+     * preprocessing.
+     */
+#if ENOTEMPTY != EEXIST
+    case ENOTEMPTY:
+      return NS_ERROR_FILE_DIR_NOT_EMPTY;
+#endif /* ENOTEMPTY != EEXIST */
+    /* Note that nsIFile.createUnique() returns
+       NS_ERROR_FILE_TOO_BIG when it cannot create a temporary
+       file with a unique filename.
+       See https://developer.mozilla.org/en-US/docs/Table_Of_Errors
+       Other usages of NS_ERROR_FILE_TOO_BIG in the source tree
+       are in line with the POSIX semantics of EFBIG.
+       So this is a reasonably good approximation.
+    */
+    case EFBIG: /*     File too large. */
+      return NS_ERROR_FILE_TOO_BIG;
+
+    default:
+      return NS_ERROR_FAILURE;
+  }
+}
+
+#define NSRESULT_FOR_ERRNO() nsresultForErrno(errno)
+
+void NS_StartupLocalFile();
+void NS_ShutdownLocalFile();
+
+#endif
diff --git a/xpcom/io/nsLocalFileCommon.cpp b/xpcom/io/nsLocalFileCommon.cpp
new file mode 100644
index 000000000..8fbb7227d
--- /dev/null
+++ b/xpcom/io/nsLocalFileCommon.cpp
@@ -0,0 +1,328 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIServiceManager.h"
+
+#include "nsLocalFile.h" // includes platform-specific headers
+
+#include "nsString.h"
+#include "nsCOMPtr.h"
+#include "nsReadableUtils.h"
+#include "nsPrintfCString.h"
+#include "nsCRT.h"
+#include "nsNativeCharsetUtils.h"
+#include "nsUTF8Utils.h"
+
+#ifdef XP_WIN
+#include <string.h>
+#endif
+
+
+void
+NS_StartupLocalFile()
+{
+  nsLocalFile::GlobalInit();
+}
+
+void
+NS_ShutdownLocalFile()
+{
+  nsLocalFile::GlobalShutdown();
+}
+
+#if !defined(MOZ_WIDGET_COCOA) && !defined(XP_WIN)
+NS_IMETHODIMP
+nsLocalFile::InitWithFile(nsIFile* aFile)
+{
+  if (NS_WARN_IF(!aFile)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsAutoCString path;
+  aFile->GetNativePath(path);
+  if (path.IsEmpty()) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  return InitWithNativePath(path);
+}
+#endif
+
+#define kMaxFilenameLength 255
+#define kMaxExtensionLength 100
+#define kMaxSequenceNumberLength 5 // "-9999"
+// requirement: kMaxExtensionLength < kMaxFilenameLength - kMaxSequenceNumberLength
+
+NS_IMETHODIMP
+nsLocalFile::CreateUnique(uint32_t aType, uint32_t aAttributes)
+{
+  nsresult rv;
+  bool longName;
+
+#ifdef XP_WIN
+  nsAutoString pathName, leafName, rootName, suffix;
+  rv = GetPath(pathName);
+#else
+  nsAutoCString pathName, leafName, rootName, suffix;
+  rv = GetNativePath(pathName);
+#endif
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  longName = (pathName.Length() + kMaxSequenceNumberLength >
+              kMaxFilenameLength);
+  if (!longName) {
+    rv = Create(aType, aAttributes);
+    if (rv != NS_ERROR_FILE_ALREADY_EXISTS) {
+      return rv;
+    }
+  }
+
+#ifdef XP_WIN
+  rv = GetLeafName(leafName);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  const int32_t lastDot = leafName.RFindChar(char16_t('.'));
+#else
+  rv = GetNativeLeafName(leafName);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  const int32_t lastDot = leafName.RFindChar('.');
+#endif
+
+  if (lastDot == kNotFound) {
+    rootName = leafName;
+  } else {
+    suffix = Substring(leafName, lastDot);      // include '.'
+    rootName = Substring(leafName, 0, lastDot); // strip suffix and dot
+  }
+
+  if (longName) {
+    int32_t maxRootLength = (kMaxFilenameLength -
+                             (pathName.Length() - leafName.Length()) -
+                             suffix.Length() - kMaxSequenceNumberLength);
+
+    // We cannot create an item inside a directory whose name is too long.
+    // Also, ensure that at least one character remains after we truncate
+    // the root name, as we don't want to end up with an empty leaf name.
+    if (maxRootLength < 2) {
+      return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+    }
+
+#ifdef XP_WIN
+    // ensure that we don't cut the name in mid-UTF16-character
+    rootName.SetLength(NS_IS_LOW_SURROGATE(rootName[maxRootLength]) ?
+                       maxRootLength - 1 : maxRootLength);
+    SetLeafName(rootName + suffix);
+#else
+    if (NS_IsNativeUTF8()) {
+      // ensure that we don't cut the name in mid-UTF8-character
+      // (assume the name is valid UTF8 to begin with)
+      while (UTF8traits::isInSeq(rootName[maxRootLength])) {
+        --maxRootLength;
+      }
+
+      // Another check to avoid ending up with an empty leaf name.
+      if (maxRootLength == 0 && suffix.IsEmpty()) {
+        return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+      }
+    }
+
+    rootName.SetLength(maxRootLength);
+    SetNativeLeafName(rootName + suffix);
+#endif
+    nsresult rvCreate = Create(aType, aAttributes);
+    if (rvCreate != NS_ERROR_FILE_ALREADY_EXISTS) {
+      return rvCreate;
+    }
+  }
+
+  for (int indx = 1; indx < 10000; ++indx) {
+    // start with "Picture-1.jpg" after "Picture.jpg" exists
+#ifdef XP_WIN
+    SetLeafName(rootName +
+                NS_ConvertASCIItoUTF16(nsPrintfCString("-%d", indx)) +
+                suffix);
+#else
+    SetNativeLeafName(rootName + nsPrintfCString("-%d", indx) + suffix);
+#endif
+    rv = Create(aType, aAttributes);
+    if (NS_SUCCEEDED(rv) || rv != NS_ERROR_FILE_ALREADY_EXISTS) {
+      return rv;
+    }
+  }
+
+  // The disk is full, sort of
+  return NS_ERROR_FILE_TOO_BIG;
+}
+
+#if defined(XP_WIN)
+static const char16_t kPathSeparatorChar       = '\\';
+#elif defined(XP_UNIX)
+static const char16_t kPathSeparatorChar       = '/';
+#else
+#error Need to define file path separator for your platform
+#endif
+
+static void
+SplitPath(char16_t* aPath, nsTArray<char16_t*>& aNodeArray)
+{
+  if (*aPath == 0) {
+    return;
+  }
+
+  if (*aPath == kPathSeparatorChar) {
+    aPath++;
+  }
+  aNodeArray.AppendElement(aPath);
+
+  for (char16_t* cp = aPath; *cp != 0; ++cp) {
+    if (*cp == kPathSeparatorChar) {
+      *cp++ = 0;
+      if (*cp == 0) {
+        break;
+      }
+      aNodeArray.AppendElement(cp);
+    }
+  }
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::GetRelativeDescriptor(nsIFile* aFromFile, nsACString& aResult)
+{
+  if (NS_WARN_IF(!aFromFile)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  //
+  // aResult will be UTF-8 encoded
+  //
+
+  nsresult rv;
+  aResult.Truncate(0);
+
+  nsAutoString thisPath, fromPath;
+  AutoTArray<char16_t*, 32> thisNodes;
+  AutoTArray<char16_t*, 32> fromNodes;
+
+  rv = GetPath(thisPath);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  rv = aFromFile->GetPath(fromPath);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // get raw pointer to mutable string buffer
+  char16_t* thisPathPtr;
+  thisPath.BeginWriting(thisPathPtr);
+  char16_t* fromPathPtr;
+  fromPath.BeginWriting(fromPathPtr);
+
+  SplitPath(thisPathPtr, thisNodes);
+  SplitPath(fromPathPtr, fromNodes);
+
+  size_t nodeIndex;
+  for (nodeIndex = 0;
+       nodeIndex < thisNodes.Length() && nodeIndex < fromNodes.Length();
+       ++nodeIndex) {
+#ifdef XP_WIN
+    if (_wcsicmp(char16ptr_t(thisNodes[nodeIndex]),
+                 char16ptr_t(fromNodes[nodeIndex]))) {
+      break;
+    }
+#else
+    if (nsCRT::strcmp(thisNodes[nodeIndex], fromNodes[nodeIndex])) {
+      break;
+    }
+#endif
+  }
+
+  size_t branchIndex = nodeIndex;
+  for (nodeIndex = branchIndex; nodeIndex < fromNodes.Length(); ++nodeIndex) {
+    aResult.AppendLiteral("../");
+  }
+  for (nodeIndex = branchIndex; nodeIndex < thisNodes.Length(); ++nodeIndex) {
+    NS_ConvertUTF16toUTF8 nodeStr(thisNodes[nodeIndex]);
+    aResult.Append(nodeStr);
+    if (nodeIndex + 1 < thisNodes.Length()) {
+      aResult.Append('/');
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetRelativeDescriptor(nsIFile* aFromFile,
+                                   const nsACString& aRelativeDesc)
+{
+  NS_NAMED_LITERAL_CSTRING(kParentDirStr, "../");
+
+  nsCOMPtr<nsIFile> targetFile;
+  nsresult rv = aFromFile->Clone(getter_AddRefs(targetFile));
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  //
+  // aRelativeDesc is UTF-8 encoded
+  //
+
+  nsCString::const_iterator strBegin, strEnd;
+  aRelativeDesc.BeginReading(strBegin);
+  aRelativeDesc.EndReading(strEnd);
+
+  nsCString::const_iterator nodeBegin(strBegin), nodeEnd(strEnd);
+  nsCString::const_iterator pos(strBegin);
+
+  nsCOMPtr<nsIFile> parentDir;
+  while (FindInReadable(kParentDirStr, nodeBegin, nodeEnd)) {
+    rv = targetFile->GetParent(getter_AddRefs(parentDir));
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+    if (!parentDir) {
+      return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+    }
+    targetFile = parentDir;
+
+    nodeBegin = nodeEnd;
+    pos = nodeEnd;
+    nodeEnd = strEnd;
+  }
+
+  nodeBegin = nodeEnd = pos;
+  while (nodeEnd != strEnd) {
+    FindCharInReadable('/', nodeEnd, strEnd);
+    targetFile->Append(NS_ConvertUTF8toUTF16(Substring(nodeBegin, nodeEnd)));
+    if (nodeEnd != strEnd) { // If there's more left in the string, inc over the '/' nodeEnd is on.
+      ++nodeEnd;
+    }
+    nodeBegin = nodeEnd;
+  }
+
+  return InitWithFile(targetFile);
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetRelativePath(nsIFile* aFromFile, nsACString& aResult)
+{
+  return GetRelativeDescriptor(aFromFile, aResult);
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetRelativePath(nsIFile* aFromFile,
+                             const nsACString& aRelativePath)
+{
+  return SetRelativeDescriptor(aFromFile, aRelativePath);
+}
diff --git a/xpcom/io/nsLocalFileUnix.cpp b/xpcom/io/nsLocalFileUnix.cpp
new file mode 100644
index 000000000..194e5835e
--- /dev/null
+++ b/xpcom/io/nsLocalFileUnix.cpp
@@ -0,0 +1,2715 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * Implementation of nsIFile for "unixy" systems.
+ */
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Sprintf.h"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <utime.h>
+#include <dirent.h>
+#include <ctype.h>
+#include <locale.h>
+
+#if defined(HAVE_SYS_QUOTA_H) && defined(HAVE_LINUX_QUOTA_H)
+#define USE_LINUX_QUOTACTL
+#include <sys/mount.h>
+#include <sys/quota.h>
+#include <sys/sysmacros.h>
+#ifndef BLOCK_SIZE
+#define BLOCK_SIZE 1024 /* kernel block size */
+#endif
+#endif
+
+#include "xpcom-private.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsCRT.h"
+#include "nsCOMPtr.h"
+#include "nsMemory.h"
+#include "nsIFile.h"
+#include "nsString.h"
+#include "nsReadableUtils.h"
+#include "nsLocalFile.h"
+#include "nsIComponentManager.h"
+#include "nsXPIDLString.h"
+#include "prproces.h"
+#include "nsIDirectoryEnumerator.h"
+#include "nsISimpleEnumerator.h"
+#include "private/pprio.h"
+#include "prlink.h"
+
+#ifdef MOZ_WIDGET_GTK
+#include "nsIGIOService.h"
+#endif
+
+#ifdef MOZ_WIDGET_COCOA
+#include <Carbon/Carbon.h>
+#include "CocoaFileUtils.h"
+#include "prmem.h"
+#include "plbase64.h"
+
+static nsresult MacErrorMapper(OSErr inErr);
+#endif
+
+#ifdef MOZ_WIDGET_ANDROID
+#include "GeneratedJNIWrappers.h"
+#include "nsIMIMEService.h"
+#include <linux/magic.h>
+#endif
+
+#ifdef MOZ_ENABLE_CONTENTACTION
+#include <contentaction/contentaction.h>
+#endif
+
+#include "nsNativeCharsetUtils.h"
+#include "nsTraceRefcnt.h"
+#include "nsHashKeys.h"
+
+using namespace mozilla;
+
+#define ENSURE_STAT_CACHE()                     \
+    PR_BEGIN_MACRO                              \
+        if (!FillStatCache())                   \
+             return NSRESULT_FOR_ERRNO();       \
+    PR_END_MACRO
+
+#define CHECK_mPath()                           \
+    PR_BEGIN_MACRO                              \
+        if (mPath.IsEmpty())                    \
+            return NS_ERROR_NOT_INITIALIZED;    \
+    PR_END_MACRO
+
+/* directory enumerator */
+class nsDirEnumeratorUnix final
+  : public nsISimpleEnumerator
+  , public nsIDirectoryEnumerator
+{
+public:
+  nsDirEnumeratorUnix();
+
+  // nsISupports interface
+  NS_DECL_ISUPPORTS
+
+  // nsISimpleEnumerator interface
+  NS_DECL_NSISIMPLEENUMERATOR
+
+  // nsIDirectoryEnumerator interface
+  NS_DECL_NSIDIRECTORYENUMERATOR
+
+  NS_IMETHOD Init(nsLocalFile* aParent, bool aIgnored);
+
+private:
+  ~nsDirEnumeratorUnix();
+
+protected:
+  NS_IMETHOD GetNextEntry();
+
+  DIR*           mDir;
+  struct dirent* mEntry;
+  nsCString      mParentPath;
+};
+
+nsDirEnumeratorUnix::nsDirEnumeratorUnix() :
+  mDir(nullptr),
+  mEntry(nullptr)
+{
+}
+
+nsDirEnumeratorUnix::~nsDirEnumeratorUnix()
+{
+  Close();
+}
+
+NS_IMPL_ISUPPORTS(nsDirEnumeratorUnix, nsISimpleEnumerator,
+                  nsIDirectoryEnumerator)
+
+NS_IMETHODIMP
+nsDirEnumeratorUnix::Init(nsLocalFile* aParent,
+                          bool aResolveSymlinks /*ignored*/)
+{
+  nsAutoCString dirPath;
+  if (NS_FAILED(aParent->GetNativePath(dirPath)) ||
+      dirPath.IsEmpty()) {
+    return NS_ERROR_FILE_INVALID_PATH;
+  }
+
+  if (NS_FAILED(aParent->GetNativePath(mParentPath))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  mDir = opendir(dirPath.get());
+  if (!mDir) {
+    return NSRESULT_FOR_ERRNO();
+  }
+  return GetNextEntry();
+}
+
+NS_IMETHODIMP
+nsDirEnumeratorUnix::HasMoreElements(bool* aResult)
+{
+  *aResult = mDir && mEntry;
+  if (!*aResult) {
+    Close();
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDirEnumeratorUnix::GetNext(nsISupports** aResult)
+{
+  nsCOMPtr<nsIFile> file;
+  nsresult rv = GetNextFile(getter_AddRefs(file));
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  NS_IF_ADDREF(*aResult = file);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDirEnumeratorUnix::GetNextEntry()
+{
+  do {
+    errno = 0;
+    mEntry = readdir(mDir);
+
+    // end of dir or error
+    if (!mEntry) {
+      return NSRESULT_FOR_ERRNO();
+    }
+
+    // keep going past "." and ".."
+  } while (mEntry->d_name[0] == '.'     &&
+           (mEntry->d_name[1] == '\0'    ||   // .\0
+            (mEntry->d_name[1] == '.'     &&
+             mEntry->d_name[2] == '\0')));      // ..\0
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDirEnumeratorUnix::GetNextFile(nsIFile** aResult)
+{
+  nsresult rv;
+  if (!mDir || !mEntry) {
+    *aResult = nullptr;
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIFile> file = new nsLocalFile();
+
+  if (NS_FAILED(rv = file->InitWithNativePath(mParentPath)) ||
+      NS_FAILED(rv = file->AppendNative(nsDependentCString(mEntry->d_name)))) {
+    return rv;
+  }
+
+  file.forget(aResult);
+  return GetNextEntry();
+}
+
+NS_IMETHODIMP
+nsDirEnumeratorUnix::Close()
+{
+  if (mDir) {
+    closedir(mDir);
+    mDir = nullptr;
+  }
+  return NS_OK;
+}
+
+nsLocalFile::nsLocalFile()
+{
+}
+
+nsLocalFile::nsLocalFile(const nsLocalFile& aOther)
+  : mPath(aOther.mPath)
+{
+}
+
+#ifdef MOZ_WIDGET_COCOA
+NS_IMPL_ISUPPORTS(nsLocalFile,
+                  nsILocalFileMac,
+                  nsILocalFile,
+                  nsIFile,
+                  nsIHashable)
+#else
+NS_IMPL_ISUPPORTS(nsLocalFile,
+                  nsILocalFile,
+                  nsIFile,
+                  nsIHashable)
+#endif
+
+nsresult
+nsLocalFile::nsLocalFileConstructor(nsISupports* aOuter,
+                                    const nsIID& aIID,
+                                    void** aInstancePtr)
+{
+  if (NS_WARN_IF(!aInstancePtr)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  if (NS_WARN_IF(aOuter)) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+
+  *aInstancePtr = nullptr;
+
+  nsCOMPtr<nsIFile> inst = new nsLocalFile();
+  return inst->QueryInterface(aIID, aInstancePtr);
+}
+
+bool
+nsLocalFile::FillStatCache()
+{
+  if (STAT(mPath.get(), &mCachedStat) == -1) {
+    // try lstat it may be a symlink
+    if (LSTAT(mPath.get(), &mCachedStat) == -1) {
+      return false;
+    }
+  }
+  return true;
+}
+
+NS_IMETHODIMP
+nsLocalFile::Clone(nsIFile** aFile)
+{
+  // Just copy-construct ourselves
+  RefPtr<nsLocalFile> copy = new nsLocalFile(*this);
+  copy.forget(aFile);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::InitWithNativePath(const nsACString& aFilePath)
+{
+  if (aFilePath.EqualsLiteral("~") ||
+      Substring(aFilePath, 0, 2).EqualsLiteral("~/")) {
+    nsCOMPtr<nsIFile> homeDir;
+    nsAutoCString homePath;
+    if (NS_FAILED(NS_GetSpecialDirectory(NS_OS_HOME_DIR,
+                                         getter_AddRefs(homeDir))) ||
+        NS_FAILED(homeDir->GetNativePath(homePath))) {
+      return NS_ERROR_FAILURE;
+    }
+
+    mPath = homePath;
+    if (aFilePath.Length() > 2) {
+      mPath.Append(Substring(aFilePath, 1, aFilePath.Length() - 1));
+    }
+  } else {
+    if (aFilePath.IsEmpty() || aFilePath.First() != '/') {
+      return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+    }
+    mPath = aFilePath;
+  }
+
+  // trim off trailing slashes
+  ssize_t len = mPath.Length();
+  while ((len > 1) && (mPath[len - 1] == '/')) {
+    --len;
+  }
+  mPath.SetLength(len);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::CreateAllAncestors(uint32_t aPermissions)
+{
+  // <jband> I promise to play nice
+  char* buffer = mPath.BeginWriting();
+  char* slashp = buffer;
+
+#ifdef DEBUG_NSIFILE
+  fprintf(stderr, "nsIFile: before: %s\n", buffer);
+#endif
+
+  while ((slashp = strchr(slashp + 1, '/'))) {
+    /*
+     * Sequences of '/' are equivalent to a single '/'.
+     */
+    if (slashp[1] == '/') {
+      continue;
+    }
+
+    /*
+     * If the path has a trailing slash, don't make the last component,
+     * because we'll get EEXIST in Create when we try to build the final
+     * component again, and it's easier to condition the logic here than
+     * there.
+     */
+    if (slashp[1] == '\0') {
+      break;
+    }
+
+    /* Temporarily NUL-terminate here */
+    *slashp = '\0';
+#ifdef DEBUG_NSIFILE
+    fprintf(stderr, "nsIFile: mkdir(\"%s\")\n", buffer);
+#endif
+    int mkdir_result = mkdir(buffer, aPermissions);
+    int mkdir_errno  = errno;
+    if (mkdir_result == -1) {
+      /*
+       * Always set |errno| to EEXIST if the dir already exists
+       * (we have to do this here since the errno value is not consistent
+       * in all cases - various reasons like different platform,
+       * automounter-controlled dir, etc. can affect it (see bug 125489
+       * for details)).
+       */
+      if (access(buffer, F_OK) == 0) {
+        mkdir_errno = EEXIST;
+      }
+    }
+
+    /* Put the / back before we (maybe) return */
+    *slashp = '/';
+
+    /*
+     * We could get EEXIST for an existing file -- not directory --
+     * with the name of one of our ancestors, but that's OK: we'll get
+     * ENOTDIR when we try to make the next component in the path,
+     * either here on back in Create, and error out appropriately.
+     */
+    if (mkdir_result == -1 && mkdir_errno != EEXIST) {
+      return nsresultForErrno(mkdir_errno);
+    }
+  }
+
+#ifdef DEBUG_NSIFILE
+  fprintf(stderr, "nsIFile: after: %s\n", buffer);
+#endif
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::OpenNSPRFileDesc(int32_t aFlags, int32_t aMode,
+                              PRFileDesc** aResult)
+{
+  *aResult = PR_Open(mPath.get(), aFlags, aMode);
+  if (!*aResult) {
+    return NS_ErrorAccordingToNSPR();
+  }
+
+  if (aFlags & DELETE_ON_CLOSE) {
+    PR_Delete(mPath.get());
+  }
+
+#if defined(HAVE_POSIX_FADVISE)
+  if (aFlags & OS_READAHEAD) {
+    posix_fadvise(PR_FileDesc2NativeHandle(*aResult), 0, 0,
+                  POSIX_FADV_SEQUENTIAL);
+  }
+#endif
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::OpenANSIFileDesc(const char* aMode, FILE** aResult)
+{
+  *aResult = fopen(mPath.get(), aMode);
+  if (!*aResult) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+static int
+do_create(const char* aPath, int aFlags, mode_t aMode, PRFileDesc** aResult)
+{
+  *aResult = PR_Open(aPath, aFlags, aMode);
+  return *aResult ? 0 : -1;
+}
+
+static int
+do_mkdir(const char* aPath, int aFlags, mode_t aMode, PRFileDesc** aResult)
+{
+  *aResult = nullptr;
+  return mkdir(aPath, aMode);
+}
+
+nsresult
+nsLocalFile::CreateAndKeepOpen(uint32_t aType, int aFlags,
+                               uint32_t aPermissions, PRFileDesc** aResult)
+{
+  if (aType != NORMAL_FILE_TYPE && aType != DIRECTORY_TYPE) {
+    return NS_ERROR_FILE_UNKNOWN_TYPE;
+  }
+
+  int (*createFunc)(const char*, int, mode_t, PRFileDesc**) =
+    (aType == NORMAL_FILE_TYPE) ? do_create : do_mkdir;
+
+  int result = createFunc(mPath.get(), aFlags, aPermissions, aResult);
+  if (result == -1 && errno == ENOENT) {
+    /*
+     * If we failed because of missing ancestor components, try to create
+     * them and then retry the original creation.
+     *
+     * Ancestor directories get the same permissions as the file we're
+     * creating, with the X bit set for each of (user,group,other) with
+     * an R bit in the original permissions.    If you want to do anything
+     * fancy like setgid or sticky bits, do it by hand.
+     */
+    int dirperm = aPermissions;
+    if (aPermissions & S_IRUSR) {
+      dirperm |= S_IXUSR;
+    }
+    if (aPermissions & S_IRGRP) {
+      dirperm |= S_IXGRP;
+    }
+    if (aPermissions & S_IROTH) {
+      dirperm |= S_IXOTH;
+    }
+
+#ifdef DEBUG_NSIFILE
+    fprintf(stderr, "nsIFile: perm = %o, dirperm = %o\n", aPermissions,
+            dirperm);
+#endif
+
+    if (NS_FAILED(CreateAllAncestors(dirperm))) {
+      return NS_ERROR_FAILURE;
+    }
+
+#ifdef DEBUG_NSIFILE
+    fprintf(stderr, "nsIFile: Create(\"%s\") again\n", mPath.get());
+#endif
+    result = createFunc(mPath.get(), aFlags, aPermissions, aResult);
+  }
+  return NSRESULT_FOR_RETURN(result);
+}
+
+NS_IMETHODIMP
+nsLocalFile::Create(uint32_t aType, uint32_t aPermissions)
+{
+  PRFileDesc* junk = nullptr;
+  nsresult rv = CreateAndKeepOpen(aType,
+                                  PR_WRONLY | PR_CREATE_FILE | PR_TRUNCATE |
+                                  PR_EXCL,
+                                  aPermissions,
+                                  &junk);
+  if (junk) {
+    PR_Close(junk);
+  }
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::AppendNative(const nsACString& aFragment)
+{
+  if (aFragment.IsEmpty()) {
+    return NS_OK;
+  }
+
+  // only one component of path can be appended
+  nsACString::const_iterator begin, end;
+  if (FindCharInReadable('/', aFragment.BeginReading(begin),
+                         aFragment.EndReading(end))) {
+    return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+  }
+
+  return AppendRelativeNativePath(aFragment);
+}
+
+NS_IMETHODIMP
+nsLocalFile::AppendRelativeNativePath(const nsACString& aFragment)
+{
+  if (aFragment.IsEmpty()) {
+    return NS_OK;
+  }
+
+  // No leading '/'
+  if (aFragment.First() == '/') {
+    return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+  }
+
+  if (!mPath.EqualsLiteral("/")) {
+    mPath.Append('/');
+  }
+  mPath.Append(aFragment);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::Normalize()
+{
+  char resolved_path[PATH_MAX] = "";
+  char* resolved_path_ptr = nullptr;
+
+  resolved_path_ptr = realpath(mPath.get(), resolved_path);
+
+  // if there is an error, the return is null.
+  if (!resolved_path_ptr) {
+    return NSRESULT_FOR_ERRNO();
+  }
+
+  mPath = resolved_path;
+  return NS_OK;
+}
+
+void
+nsLocalFile::LocateNativeLeafName(nsACString::const_iterator& aBegin,
+                                  nsACString::const_iterator& aEnd)
+{
+  // XXX perhaps we should cache this??
+
+  mPath.BeginReading(aBegin);
+  mPath.EndReading(aEnd);
+
+  nsACString::const_iterator it = aEnd;
+  nsACString::const_iterator stop = aBegin;
+  --stop;
+  while (--it != stop) {
+    if (*it == '/') {
+      aBegin = ++it;
+      return;
+    }
+  }
+  // else, the entire path is the leaf name (which means this
+  // isn't an absolute path... unexpected??)
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetNativeLeafName(nsACString& aLeafName)
+{
+  nsACString::const_iterator begin, end;
+  LocateNativeLeafName(begin, end);
+  aLeafName = Substring(begin, end);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetNativeLeafName(const nsACString& aLeafName)
+{
+  nsACString::const_iterator begin, end;
+  LocateNativeLeafName(begin, end);
+  mPath.Replace(begin.get() - mPath.get(), Distance(begin, end), aLeafName);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetNativePath(nsACString& aResult)
+{
+  aResult = mPath;
+  return NS_OK;
+}
+
+nsresult
+nsLocalFile::GetNativeTargetPathName(nsIFile* aNewParent,
+                                     const nsACString& aNewName,
+                                     nsACString& aResult)
+{
+  nsresult rv;
+  nsCOMPtr<nsIFile> oldParent;
+
+  if (!aNewParent) {
+    if (NS_FAILED(rv = GetParent(getter_AddRefs(oldParent)))) {
+      return rv;
+    }
+    aNewParent = oldParent.get();
+  } else {
+    // check to see if our target directory exists
+    bool targetExists;
+    if (NS_FAILED(rv = aNewParent->Exists(&targetExists))) {
+      return rv;
+    }
+
+    if (!targetExists) {
+      // XXX create the new directory with some permissions
+      rv = aNewParent->Create(DIRECTORY_TYPE, 0755);
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+    } else {
+      // make sure that the target is actually a directory
+      bool targetIsDirectory;
+      if (NS_FAILED(rv = aNewParent->IsDirectory(&targetIsDirectory))) {
+        return rv;
+      }
+      if (!targetIsDirectory) {
+        return NS_ERROR_FILE_DESTINATION_NOT_DIR;
+      }
+    }
+  }
+
+  nsACString::const_iterator nameBegin, nameEnd;
+  if (!aNewName.IsEmpty()) {
+    aNewName.BeginReading(nameBegin);
+    aNewName.EndReading(nameEnd);
+  } else {
+    LocateNativeLeafName(nameBegin, nameEnd);
+  }
+
+  nsAutoCString dirName;
+  if (NS_FAILED(rv = aNewParent->GetNativePath(dirName))) {
+    return rv;
+  }
+
+  aResult = dirName + NS_LITERAL_CSTRING("/") + Substring(nameBegin, nameEnd);
+  return NS_OK;
+}
+
+nsresult
+nsLocalFile::CopyDirectoryTo(nsIFile* aNewParent)
+{
+  nsresult rv;
+  /*
+   * dirCheck is used for various boolean test results such as from Equals,
+   * Exists, isDir, etc.
+   */
+  bool dirCheck, isSymlink;
+  uint32_t oldPerms;
+
+  if (NS_FAILED(rv = IsDirectory(&dirCheck))) {
+    return rv;
+  }
+  if (!dirCheck) {
+    return CopyToNative(aNewParent, EmptyCString());
+  }
+
+  if (NS_FAILED(rv = Equals(aNewParent, &dirCheck))) {
+    return rv;
+  }
+  if (dirCheck) {
+    // can't copy dir to itself
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  if (NS_FAILED(rv = aNewParent->Exists(&dirCheck))) {
+    return rv;
+  }
+  // get the dirs old permissions
+  if (NS_FAILED(rv = GetPermissions(&oldPerms))) {
+    return rv;
+  }
+  if (!dirCheck) {
+    if (NS_FAILED(rv = aNewParent->Create(DIRECTORY_TYPE, oldPerms))) {
+      return rv;
+    }
+  } else {    // dir exists lets try to use leaf
+    nsAutoCString leafName;
+    if (NS_FAILED(rv = GetNativeLeafName(leafName))) {
+      return rv;
+    }
+    if (NS_FAILED(rv = aNewParent->AppendNative(leafName))) {
+      return rv;
+    }
+    if (NS_FAILED(rv = aNewParent->Exists(&dirCheck))) {
+      return rv;
+    }
+    if (dirCheck) {
+      return NS_ERROR_FILE_ALREADY_EXISTS;  // dest exists
+    }
+    if (NS_FAILED(rv = aNewParent->Create(DIRECTORY_TYPE, oldPerms))) {
+      return rv;
+    }
+  }
+
+  nsCOMPtr<nsISimpleEnumerator> dirIterator;
+  if (NS_FAILED(rv = GetDirectoryEntries(getter_AddRefs(dirIterator)))) {
+    return rv;
+  }
+
+  bool hasMore = false;
+  while (dirIterator->HasMoreElements(&hasMore), hasMore) {
+    nsCOMPtr<nsISupports> supports;
+    nsCOMPtr<nsIFile> entry;
+    rv = dirIterator->GetNext(getter_AddRefs(supports));
+    entry = do_QueryInterface(supports);
+    if (NS_FAILED(rv) || !entry) {
+      continue;
+    }
+    if (NS_FAILED(rv = entry->IsSymlink(&isSymlink))) {
+      return rv;
+    }
+    if (NS_FAILED(rv = entry->IsDirectory(&dirCheck))) {
+      return rv;
+    }
+    if (dirCheck && !isSymlink) {
+      nsCOMPtr<nsIFile> destClone;
+      rv = aNewParent->Clone(getter_AddRefs(destClone));
+      if (NS_SUCCEEDED(rv)) {
+        if (NS_FAILED(rv = entry->CopyToNative(destClone, EmptyCString()))) {
+#ifdef DEBUG
+          nsresult rv2;
+          nsAutoCString pathName;
+          if (NS_FAILED(rv2 = entry->GetNativePath(pathName))) {
+            return rv2;
+          }
+          printf("Operation not supported: %s\n", pathName.get());
+#endif
+          if (rv == NS_ERROR_OUT_OF_MEMORY) {
+            return rv;
+          }
+          continue;
+        }
+      }
+    } else {
+      if (NS_FAILED(rv = entry->CopyToNative(aNewParent, EmptyCString()))) {
+#ifdef DEBUG
+        nsresult rv2;
+        nsAutoCString pathName;
+        if (NS_FAILED(rv2 = entry->GetNativePath(pathName))) {
+          return rv2;
+        }
+        printf("Operation not supported: %s\n", pathName.get());
+#endif
+        if (rv == NS_ERROR_OUT_OF_MEMORY) {
+          return rv;
+        }
+        continue;
+      }
+    }
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::CopyToNative(nsIFile* aNewParent, const nsACString& aNewName)
+{
+  nsresult rv;
+  // check to make sure that this has been initialized properly
+  CHECK_mPath();
+
+  // we copy the parent here so 'aNewParent' remains immutable
+  nsCOMPtr <nsIFile> workParent;
+  if (aNewParent) {
+    if (NS_FAILED(rv = aNewParent->Clone(getter_AddRefs(workParent)))) {
+      return rv;
+    }
+  } else {
+    if (NS_FAILED(rv = GetParent(getter_AddRefs(workParent)))) {
+      return rv;
+    }
+  }
+
+  // check to see if we are a directory or if we are a file
+  bool isDirectory;
+  if (NS_FAILED(rv = IsDirectory(&isDirectory))) {
+    return rv;
+  }
+
+  nsAutoCString newPathName;
+  if (isDirectory) {
+    if (!aNewName.IsEmpty()) {
+      if (NS_FAILED(rv = workParent->AppendNative(aNewName))) {
+        return rv;
+      }
+    } else {
+      if (NS_FAILED(rv = GetNativeLeafName(newPathName))) {
+        return rv;
+      }
+      if (NS_FAILED(rv = workParent->AppendNative(newPathName))) {
+        return rv;
+      }
+    }
+    if (NS_FAILED(rv = CopyDirectoryTo(workParent))) {
+      return rv;
+    }
+  } else {
+    rv = GetNativeTargetPathName(workParent, aNewName, newPathName);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+#ifdef DEBUG_blizzard
+    printf("nsLocalFile::CopyTo() %s -> %s\n", mPath.get(), newPathName.get());
+#endif
+
+    // actually create the file.
+    nsLocalFile* newFile = new nsLocalFile();
+    nsCOMPtr<nsIFile> fileRef(newFile); // release on exit
+
+    rv = newFile->InitWithNativePath(newPathName);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    // get the old permissions
+    uint32_t myPerms;
+    GetPermissions(&myPerms);
+
+    // Create the new file with the old file's permissions, even if write
+    // permission is missing.  We can't create with write permission and
+    // then change back to myPerm on all filesystems (FAT on Linux, e.g.).
+    // But we can write to a read-only file on all Unix filesystems if we
+    // open it successfully for writing.
+
+    PRFileDesc* newFD;
+    rv = newFile->CreateAndKeepOpen(NORMAL_FILE_TYPE,
+                                    PR_WRONLY | PR_CREATE_FILE | PR_TRUNCATE,
+                                    myPerms,
+                                    &newFD);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    // open the old file, too
+    bool specialFile;
+    if (NS_FAILED(rv = IsSpecial(&specialFile))) {
+      PR_Close(newFD);
+      return rv;
+    }
+    if (specialFile) {
+#ifdef DEBUG
+      printf("Operation not supported: %s\n", mPath.get());
+#endif
+      // make sure to clean up properly
+      PR_Close(newFD);
+      return NS_OK;
+    }
+
+    PRFileDesc* oldFD;
+    rv = OpenNSPRFileDesc(PR_RDONLY, myPerms, &oldFD);
+    if (NS_FAILED(rv)) {
+      // make sure to clean up properly
+      PR_Close(newFD);
+      return rv;
+    }
+
+#ifdef DEBUG_blizzard
+    int32_t totalRead = 0;
+    int32_t totalWritten = 0;
+#endif
+    char buf[BUFSIZ];
+    int32_t bytesRead;
+
+    // record PR_Write() error for better error message later.
+    nsresult saved_write_error = NS_OK;
+    nsresult saved_read_error = NS_OK;
+    nsresult saved_read_close_error = NS_OK;
+    nsresult saved_write_close_error = NS_OK;
+
+    // DONE: Does PR_Read() return bytesRead < 0 for error?
+    // Yes., The errors from PR_Read are not so common and
+    // the value may not have correspondence in NS_ERROR_*, but
+    // we do catch it still, immediately after while() loop.
+    // We can differentiate errors pf PR_Read and PR_Write by
+    // looking at saved_write_error value. If PR_Write error occurs (and not
+    // PR_Read() error), save_write_error is not NS_OK.
+
+    while ((bytesRead = PR_Read(oldFD, buf, BUFSIZ)) > 0) {
+#ifdef DEBUG_blizzard
+      totalRead += bytesRead;
+#endif
+
+      // PR_Write promises never to do a short write
+      int32_t bytesWritten = PR_Write(newFD, buf, bytesRead);
+      if (bytesWritten < 0) {
+        saved_write_error = NSRESULT_FOR_ERRNO();
+        bytesRead = -1;
+        break;
+      }
+      NS_ASSERTION(bytesWritten == bytesRead, "short PR_Write?");
+
+#ifdef DEBUG_blizzard
+      totalWritten += bytesWritten;
+#endif
+    }
+
+    // TODO/FIXME: If CIFS (and NFS?) may force read/write to return EINTR,
+    // we are better off to prepare for retrying. But we need confirmation if
+    // EINTR is returned.
+
+    // Record error if PR_Read() failed.
+    // Must be done before any other I/O which may reset errno.
+    if (bytesRead < 0 && saved_write_error == NS_OK) {
+      saved_read_error = NSRESULT_FOR_ERRNO();
+    }
+
+#ifdef DEBUG_blizzard
+    printf("read %d bytes, wrote %d bytes\n",
+           totalRead, totalWritten);
+#endif
+
+    // DONE: Errors of close can occur.  Read man page of
+    // close(2);
+    // This is likely to happen if the file system is remote file
+    // system (NFS, CIFS, etc.) and network outage occurs.
+    // At least, we should tell the user that filesystem/disk is
+    // hosed (possibly due to network error, hard disk failure,
+    // etc.) so that users can take remedial action.
+
+    // close the files
+    if (PR_Close(newFD) < 0) {
+      saved_write_close_error = NSRESULT_FOR_ERRNO();
+#if DEBUG
+      // This error merits printing.
+      fprintf(stderr, "ERROR: PR_Close(newFD) returned error. errno = %d\n", errno);
+#endif
+    }
+
+    if (PR_Close(oldFD) < 0) {
+      saved_read_close_error = NSRESULT_FOR_ERRNO();
+#if DEBUG
+      fprintf(stderr, "ERROR: PR_Close(oldFD) returned error. errno = %d\n", errno);
+#endif
+    }
+
+    // Let us report the failure to write and read.
+    // check for write/read error after cleaning up
+    if (bytesRead < 0) {
+      if (saved_write_error != NS_OK) {
+        return saved_write_error;
+      } else if (saved_read_error != NS_OK) {
+        return saved_read_error;
+      }
+#if DEBUG
+      else {              // sanity check. Die and debug.
+        MOZ_ASSERT(0);
+      }
+#endif
+    }
+
+    if (saved_write_close_error != NS_OK) {
+      return saved_write_close_error;
+    }
+    if (saved_read_close_error != NS_OK) {
+      return saved_read_close_error;
+    }
+  }
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::CopyToFollowingLinksNative(nsIFile* aNewParent,
+                                        const nsACString& aNewName)
+{
+  return CopyToNative(aNewParent, aNewName);
+}
+
+NS_IMETHODIMP
+nsLocalFile::MoveToNative(nsIFile* aNewParent, const nsACString& aNewName)
+{
+  nsresult rv;
+
+  // check to make sure that this has been initialized properly
+  CHECK_mPath();
+
+  // check to make sure that we have a new parent
+  nsAutoCString newPathName;
+  rv = GetNativeTargetPathName(aNewParent, aNewName, newPathName);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // try for atomic rename, falling back to copy/delete
+  if (rename(mPath.get(), newPathName.get()) < 0) {
+    if (errno == EXDEV) {
+      rv = CopyToNative(aNewParent, aNewName);
+      if (NS_SUCCEEDED(rv)) {
+        rv = Remove(true);
+      }
+    } else {
+      rv = NSRESULT_FOR_ERRNO();
+    }
+  }
+
+  if (NS_SUCCEEDED(rv)) {
+    // Adjust this
+    mPath = newPathName;
+  }
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::Remove(bool aRecursive)
+{
+  CHECK_mPath();
+  ENSURE_STAT_CACHE();
+
+  bool isSymLink;
+
+  nsresult rv = IsSymlink(&isSymLink);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (isSymLink || !S_ISDIR(mCachedStat.st_mode)) {
+    return NSRESULT_FOR_RETURN(unlink(mPath.get()));
+  }
+
+  if (aRecursive) {
+    nsDirEnumeratorUnix* dir = new nsDirEnumeratorUnix();
+
+    nsCOMPtr<nsISimpleEnumerator> dirRef(dir); // release on exit
+
+    rv = dir->Init(this, false);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    bool more;
+    while (dir->HasMoreElements(&more), more) {
+      nsCOMPtr<nsISupports> item;
+      rv = dir->GetNext(getter_AddRefs(item));
+      if (NS_FAILED(rv)) {
+        return NS_ERROR_FAILURE;
+      }
+
+      nsCOMPtr<nsIFile> file = do_QueryInterface(item, &rv);
+      if (NS_FAILED(rv)) {
+        return NS_ERROR_FAILURE;
+      }
+      rv = file->Remove(aRecursive);
+
+#ifdef ANDROID
+      // See bug 580434 - Bionic gives us just deleted files
+      if (rv == NS_ERROR_FILE_TARGET_DOES_NOT_EXIST) {
+        continue;
+      }
+#endif
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+    }
+  }
+
+  return NSRESULT_FOR_RETURN(rmdir(mPath.get()));
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetLastModifiedTime(PRTime* aLastModTime)
+{
+  CHECK_mPath();
+  if (NS_WARN_IF(!aLastModTime)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  PRFileInfo64 info;
+  if (PR_GetFileInfo64(mPath.get(), &info) != PR_SUCCESS) {
+    return NSRESULT_FOR_ERRNO();
+  }
+  PRTime modTime = info.modifyTime;
+  if (modTime == 0) {
+    *aLastModTime = 0;
+  } else {
+    *aLastModTime = modTime / PR_USEC_PER_MSEC;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetLastModifiedTime(PRTime aLastModTime)
+{
+  CHECK_mPath();
+
+  int result;
+  if (aLastModTime != 0) {
+    ENSURE_STAT_CACHE();
+    struct utimbuf ut;
+    ut.actime = mCachedStat.st_atime;
+
+    // convert milliseconds to seconds since the unix epoch
+    ut.modtime = (time_t)(aLastModTime / PR_MSEC_PER_SEC);
+    result = utime(mPath.get(), &ut);
+  } else {
+    result = utime(mPath.get(), nullptr);
+  }
+  return NSRESULT_FOR_RETURN(result);
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetLastModifiedTimeOfLink(PRTime* aLastModTimeOfLink)
+{
+  CHECK_mPath();
+  if (NS_WARN_IF(!aLastModTimeOfLink)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  struct STAT sbuf;
+  if (LSTAT(mPath.get(), &sbuf) == -1) {
+    return NSRESULT_FOR_ERRNO();
+  }
+  *aLastModTimeOfLink = PRTime(sbuf.st_mtime) * PR_MSEC_PER_SEC;
+
+  return NS_OK;
+}
+
+/*
+ * utime(2) may or may not dereference symlinks, joy.
+ */
+NS_IMETHODIMP
+nsLocalFile::SetLastModifiedTimeOfLink(PRTime aLastModTimeOfLink)
+{
+  return SetLastModifiedTime(aLastModTimeOfLink);
+}
+
+/*
+ * Only send back permissions bits: maybe we want to send back the whole
+ * mode_t to permit checks against other file types?
+ */
+
+#define NORMALIZE_PERMS(mode)    ((mode)& (S_IRWXU | S_IRWXG | S_IRWXO))
+
+NS_IMETHODIMP
+nsLocalFile::GetPermissions(uint32_t* aPermissions)
+{
+  if (NS_WARN_IF(!aPermissions)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  ENSURE_STAT_CACHE();
+  *aPermissions = NORMALIZE_PERMS(mCachedStat.st_mode);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetPermissionsOfLink(uint32_t* aPermissionsOfLink)
+{
+  CHECK_mPath();
+  if (NS_WARN_IF(!aPermissionsOfLink)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  struct STAT sbuf;
+  if (LSTAT(mPath.get(), &sbuf) == -1) {
+    return NSRESULT_FOR_ERRNO();
+  }
+  *aPermissionsOfLink = NORMALIZE_PERMS(sbuf.st_mode);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetPermissions(uint32_t aPermissions)
+{
+  CHECK_mPath();
+
+  /*
+   * Race condition here: we should use fchmod instead, there's no way to
+   * guarantee the name still refers to the same file.
+   */
+  if (chmod(mPath.get(), aPermissions) >= 0) {
+    return NS_OK;
+  }
+#if defined(ANDROID) && defined(STATFS)
+  // For the time being, this is restricted for use by Android, but we
+  // will figure out what to do for all platforms in bug 638503
+  struct STATFS sfs;
+  if (STATFS(mPath.get(), &sfs) < 0) {
+    return NSRESULT_FOR_ERRNO();
+  }
+
+  // if this is a FAT file system we can't set file permissions
+  if (sfs.f_type == MSDOS_SUPER_MAGIC) {
+    return NS_OK;
+  }
+#endif
+  return NSRESULT_FOR_ERRNO();
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetPermissionsOfLink(uint32_t aPermissions)
+{
+  // There isn't a consistent mechanism for doing this on UNIX platforms. We
+  // might want to carefully implement this in the future though.
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetFileSize(int64_t* aFileSize)
+{
+  if (NS_WARN_IF(!aFileSize)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  *aFileSize = 0;
+  ENSURE_STAT_CACHE();
+
+  if (!S_ISDIR(mCachedStat.st_mode)) {
+    *aFileSize = (int64_t)mCachedStat.st_size;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetFileSize(int64_t aFileSize)
+{
+  CHECK_mPath();
+
+#if defined(ANDROID)
+  /* no truncate on bionic */
+  int fd = open(mPath.get(), O_WRONLY);
+  if (fd == -1) {
+    return NSRESULT_FOR_ERRNO();
+  }
+
+  int ret = ftruncate(fd, (off_t)aFileSize);
+  close(fd);
+
+  if (ret == -1) {
+    return NSRESULT_FOR_ERRNO();
+  }
+#elif defined(HAVE_TRUNCATE64)
+  if (truncate64(mPath.get(), (off64_t)aFileSize) == -1) {
+    return NSRESULT_FOR_ERRNO();
+  }
+#else
+  off_t size = (off_t)aFileSize;
+  if (truncate(mPath.get(), size) == -1) {
+    return NSRESULT_FOR_ERRNO();
+  }
+#endif
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetFileSizeOfLink(int64_t* aFileSize)
+{
+  CHECK_mPath();
+  if (NS_WARN_IF(!aFileSize)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  struct STAT sbuf;
+  if (LSTAT(mPath.get(), &sbuf) == -1) {
+    return NSRESULT_FOR_ERRNO();
+  }
+
+  *aFileSize = (int64_t)sbuf.st_size;
+  return NS_OK;
+}
+
+#if defined(USE_LINUX_QUOTACTL)
+/*
+ * Searches /proc/self/mountinfo for given device (Major:Minor),
+ * returns exported name from /dev
+ *
+ * Fails when /proc/self/mountinfo or diven device don't exist.
+ */
+static bool
+GetDeviceName(int aDeviceMajor, int aDeviceMinor, nsACString& aDeviceName)
+{
+  bool ret = false;
+
+  const int kMountInfoLineLength = 200;
+  const int kMountInfoDevPosition = 6;
+
+  char mountinfoLine[kMountInfoLineLength];
+  char deviceNum[kMountInfoLineLength];
+
+  SprintfLiteral(deviceNum, "%d:%d", aDeviceMajor, aDeviceMinor);
+
+  FILE* f = fopen("/proc/self/mountinfo", "rt");
+  if (!f) {
+    return ret;
+  }
+
+  // Expects /proc/self/mountinfo in format:
+  // 'ID ID major:minor root mountpoint flags - type devicename flags'
+  while (fgets(mountinfoLine, kMountInfoLineLength, f)) {
+    char* p_dev = strstr(mountinfoLine, deviceNum);
+
+    for (int i = 0; i < kMountInfoDevPosition && p_dev; ++i) {
+      p_dev = strchr(p_dev, ' ');
+      if (p_dev) {
+        p_dev++;
+      }
+    }
+
+    if (p_dev) {
+      char* p_dev_end = strchr(p_dev, ' ');
+      if (p_dev_end) {
+        *p_dev_end = '\0';
+        aDeviceName.Assign(p_dev);
+        ret = true;
+        break;
+      }
+    }
+  }
+
+  fclose(f);
+  return ret;
+}
+#endif
+
+NS_IMETHODIMP
+nsLocalFile::GetDiskSpaceAvailable(int64_t* aDiskSpaceAvailable)
+{
+  if (NS_WARN_IF(!aDiskSpaceAvailable)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // These systems have the operations necessary to check disk space.
+
+#ifdef STATFS
+
+  // check to make sure that mPath is properly initialized
+  CHECK_mPath();
+
+  struct STATFS fs_buf;
+
+  /*
+   * Members of the STATFS struct that you should know about:
+   * F_BSIZE = block size on disk.
+   * f_bavail = number of free blocks available to a non-superuser.
+   * f_bfree = number of total free blocks in file system.
+   */
+
+  if (STATFS(mPath.get(), &fs_buf) < 0) {
+    // The call to STATFS failed.
+#ifdef DEBUG
+    printf("ERROR: GetDiskSpaceAvailable: STATFS call FAILED. \n");
+#endif
+    return NS_ERROR_FAILURE;
+  }
+
+  *aDiskSpaceAvailable = (int64_t)fs_buf.F_BSIZE * fs_buf.f_bavail;
+
+#ifdef DEBUG_DISK_SPACE
+  printf("DiskSpaceAvailable: %lu bytes\n",
+         *aDiskSpaceAvailable);
+#endif
+
+#if defined(USE_LINUX_QUOTACTL)
+
+  if (!FillStatCache()) {
+    // Return available size from statfs
+    return NS_OK;
+  }
+
+  nsCString deviceName;
+  if (!GetDeviceName(major(mCachedStat.st_dev),
+                     minor(mCachedStat.st_dev),
+                     deviceName)) {
+    return NS_OK;
+  }
+
+  struct dqblk dq;
+  if (!quotactl(QCMD(Q_GETQUOTA, USRQUOTA), deviceName.get(),
+                getuid(), (caddr_t)&dq)
+#ifdef QIF_BLIMITS
+      && dq.dqb_valid & QIF_BLIMITS
+#endif
+      && dq.dqb_bhardlimit) {
+    int64_t QuotaSpaceAvailable = 0;
+    // dqb_bhardlimit is count of BLOCK_SIZE blocks, dqb_curspace is bytes
+    if ((BLOCK_SIZE * dq.dqb_bhardlimit) > dq.dqb_curspace)
+      QuotaSpaceAvailable = int64_t(BLOCK_SIZE * dq.dqb_bhardlimit - dq.dqb_curspace);
+    if (QuotaSpaceAvailable < *aDiskSpaceAvailable) {
+      *aDiskSpaceAvailable = QuotaSpaceAvailable;
+    }
+  }
+#endif
+
+  return NS_OK;
+
+#else
+  /*
+   * This platform doesn't have statfs or statvfs.  I'm sure that there's
+   * a way to check for free disk space on platforms that don't have statfs
+   * (I'm SURE they have df, for example).
+   *
+   * Until we figure out how to do that, lets be honest and say that this
+   * command isn't implemented properly for these platforms yet.
+   */
+#ifdef DEBUG
+  printf("ERROR: GetDiskSpaceAvailable: Not implemented for plaforms without statfs.\n");
+#endif
+  return NS_ERROR_NOT_IMPLEMENTED;
+
+#endif /* STATFS */
+
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetParent(nsIFile** aParent)
+{
+  CHECK_mPath();
+  if (NS_WARN_IF(!aParent)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  *aParent = nullptr;
+
+  // if '/' we are at the top of the volume, return null
+  if (mPath.EqualsLiteral("/")) {
+    return  NS_OK;
+  }
+
+  // <brendan, after jband> I promise to play nice
+  char* buffer = mPath.BeginWriting();
+  // find the last significant slash in buffer
+  char* slashp = strrchr(buffer, '/');
+  NS_ASSERTION(slashp, "non-canonical path?");
+  if (!slashp) {
+    return NS_ERROR_FILE_INVALID_PATH;
+  }
+
+  // for the case where we are at '/'
+  if (slashp == buffer) {
+    slashp++;
+  }
+
+  // temporarily terminate buffer at the last significant slash
+  char c = *slashp;
+  *slashp = '\0';
+
+  nsCOMPtr<nsIFile> localFile;
+  nsresult rv = NS_NewNativeLocalFile(nsDependentCString(buffer), true,
+                                      getter_AddRefs(localFile));
+
+  // make buffer whole again
+  *slashp = c;
+
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  localFile.forget(aParent);
+  return NS_OK;
+}
+
+/*
+ * The results of Exists, isWritable and isReadable are not cached.
+ */
+
+
+NS_IMETHODIMP
+nsLocalFile::Exists(bool* aResult)
+{
+  CHECK_mPath();
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  *aResult = (access(mPath.get(), F_OK) == 0);
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::IsWritable(bool* aResult)
+{
+  CHECK_mPath();
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  *aResult = (access(mPath.get(), W_OK) == 0);
+  if (*aResult || errno == EACCES) {
+    return NS_OK;
+  }
+  return NSRESULT_FOR_ERRNO();
+}
+
+NS_IMETHODIMP
+nsLocalFile::IsReadable(bool* aResult)
+{
+  CHECK_mPath();
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  *aResult = (access(mPath.get(), R_OK) == 0);
+  if (*aResult || errno == EACCES) {
+    return NS_OK;
+  }
+  return NSRESULT_FOR_ERRNO();
+}
+
+NS_IMETHODIMP
+nsLocalFile::IsExecutable(bool* aResult)
+{
+  CHECK_mPath();
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // Check extension (bug 663899). On certain platforms, the file
+  // extension may cause the OS to treat it as executable regardless of
+  // the execute bit, such as .jar on Mac OS X. We borrow the code from
+  // nsLocalFileWin, slightly modified.
+
+  // Don't be fooled by symlinks.
+  bool symLink;
+  nsresult rv = IsSymlink(&symLink);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  nsAutoString path;
+  if (symLink) {
+    GetTarget(path);
+  } else {
+    GetPath(path);
+  }
+
+  int32_t dotIdx = path.RFindChar(char16_t('.'));
+  if (dotIdx != kNotFound) {
+    // Convert extension to lower case.
+    char16_t* p = path.BeginWriting();
+    for (p += dotIdx + 1; *p; ++p) {
+      *p += (*p >= L'A' && *p <= L'Z') ? 'a' - 'A' : 0;
+    }
+
+    // Search for any of the set of executable extensions.
+    static const char* const executableExts[] = {
+      "air",  // Adobe AIR installer
+      "jar"   // java application bundle
+    };
+    nsDependentSubstring ext = Substring(path, dotIdx + 1);
+    for (size_t i = 0; i < ArrayLength(executableExts); i++) {
+      if (ext.EqualsASCII(executableExts[i])) {
+        // Found a match.  Set result and quit.
+        *aResult = true;
+        return NS_OK;
+      }
+    }
+  }
+
+  // On OS X, then query Launch Services.
+#ifdef MOZ_WIDGET_COCOA
+  // Certain Mac applications, such as Classic applications, which
+  // run under Rosetta, might not have the +x mode bit but are still
+  // considered to be executable by Launch Services (bug 646748).
+  CFURLRef url;
+  if (NS_FAILED(GetCFURL(&url))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  LSRequestedInfo theInfoRequest = kLSRequestAllInfo;
+  LSItemInfoRecord theInfo;
+  OSStatus result = ::LSCopyItemInfoForURL(url, theInfoRequest, &theInfo);
+  ::CFRelease(url);
+  if (result == noErr) {
+    if ((theInfo.flags & kLSItemInfoIsApplication) != 0) {
+      *aResult = true;
+      return NS_OK;
+    }
+  }
+#endif
+
+  // Then check the execute bit.
+  *aResult = (access(mPath.get(), X_OK) == 0);
+#ifdef SOLARIS
+  // On Solaris, access will always return 0 for root user, however
+  // the file is only executable if S_IXUSR | S_IXGRP | S_IXOTH is set.
+  // See bug 351950, https://bugzilla.mozilla.org/show_bug.cgi?id=351950
+  if (*aResult) {
+    struct STAT buf;
+
+    *aResult = (STAT(mPath.get(), &buf) == 0);
+    if (*aResult || errno == EACCES) {
+      *aResult = *aResult && (buf.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH));
+      return NS_OK;
+    }
+
+    return NSRESULT_FOR_ERRNO();
+  }
+#endif
+  if (*aResult || errno == EACCES) {
+    return NS_OK;
+  }
+  return NSRESULT_FOR_ERRNO();
+}
+
+NS_IMETHODIMP
+nsLocalFile::IsDirectory(bool* aResult)
+{
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  *aResult = false;
+  ENSURE_STAT_CACHE();
+  *aResult = S_ISDIR(mCachedStat.st_mode);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::IsFile(bool* aResult)
+{
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  *aResult = false;
+  ENSURE_STAT_CACHE();
+  *aResult = S_ISREG(mCachedStat.st_mode);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::IsHidden(bool* aResult)
+{
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  nsACString::const_iterator begin, end;
+  LocateNativeLeafName(begin, end);
+  *aResult = (*begin == '.');
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::IsSymlink(bool* aResult)
+{
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  CHECK_mPath();
+
+  struct STAT symStat;
+  if (LSTAT(mPath.get(), &symStat) == -1) {
+    return NSRESULT_FOR_ERRNO();
+  }
+  *aResult = S_ISLNK(symStat.st_mode);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::IsSpecial(bool* aResult)
+{
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  ENSURE_STAT_CACHE();
+  *aResult = S_ISCHR(mCachedStat.st_mode)   ||
+             S_ISBLK(mCachedStat.st_mode)   ||
+#ifdef S_ISSOCK
+             S_ISSOCK(mCachedStat.st_mode)  ||
+#endif
+             S_ISFIFO(mCachedStat.st_mode);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::Equals(nsIFile* aInFile, bool* aResult)
+{
+  if (NS_WARN_IF(!aInFile)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  *aResult = false;
+
+  nsAutoCString inPath;
+  nsresult rv = aInFile->GetNativePath(inPath);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // We don't need to worry about "/foo/" vs. "/foo" here
+  // because trailing slashes are stripped on init.
+  *aResult = !strcmp(inPath.get(), mPath.get());
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::Contains(nsIFile* aInFile, bool* aResult)
+{
+  CHECK_mPath();
+  if (NS_WARN_IF(!aInFile)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsAutoCString inPath;
+  nsresult rv;
+
+  if (NS_FAILED(rv = aInFile->GetNativePath(inPath))) {
+    return rv;
+  }
+
+  *aResult = false;
+
+  ssize_t len = mPath.Length();
+  if (strncmp(mPath.get(), inPath.get(), len) == 0) {
+    // Now make sure that the |aInFile|'s path has a separator at len,
+    // which implies that it has more components after len.
+    if (inPath[len] == '/') {
+      *aResult = true;
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetNativeTarget(nsACString& aResult)
+{
+  CHECK_mPath();
+  aResult.Truncate();
+
+  struct STAT symStat;
+  if (LSTAT(mPath.get(), &symStat) == -1) {
+    return NSRESULT_FOR_ERRNO();
+  }
+
+  if (!S_ISLNK(symStat.st_mode)) {
+    return NS_ERROR_FILE_INVALID_PATH;
+  }
+
+  int32_t size = (int32_t)symStat.st_size;
+  char* target = (char*)moz_xmalloc(size + 1);
+  if (!target) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  if (readlink(mPath.get(), target, (size_t)size) < 0) {
+    free(target);
+    return NSRESULT_FOR_ERRNO();
+  }
+  target[size] = '\0';
+
+  nsresult rv = NS_OK;
+  nsCOMPtr<nsIFile> self(this);
+  int32_t maxLinks = 40;
+  while (true) {
+    if (maxLinks-- == 0) {
+      rv = NS_ERROR_FILE_UNRESOLVABLE_SYMLINK;
+      break;
+    }
+
+    if (target[0] != '/') {
+      nsCOMPtr<nsIFile> parent;
+      if (NS_FAILED(rv = self->GetParent(getter_AddRefs(parent)))) {
+        break;
+      }
+      if (NS_FAILED(rv = parent->AppendRelativeNativePath(nsDependentCString(target)))) {
+        break;
+      }
+      if (NS_FAILED(rv = parent->GetNativePath(aResult))) {
+        break;
+      }
+      self = parent;
+    } else {
+      aResult = target;
+    }
+
+    const nsPromiseFlatCString& flatRetval = PromiseFlatCString(aResult);
+
+    // Any failure in testing the current target we'll just interpret
+    // as having reached our destiny.
+    if (LSTAT(flatRetval.get(), &symStat) == -1) {
+      break;
+    }
+
+    // And of course we're done if it isn't a symlink.
+    if (!S_ISLNK(symStat.st_mode)) {
+      break;
+    }
+
+    int32_t newSize = (int32_t)symStat.st_size;
+    if (newSize > size) {
+      char* newTarget = (char*)moz_xrealloc(target, newSize + 1);
+      if (!newTarget) {
+        rv = NS_ERROR_OUT_OF_MEMORY;
+        break;
+      }
+      target = newTarget;
+      size = newSize;
+    }
+
+    int32_t linkLen = readlink(flatRetval.get(), target, size);
+    if (linkLen == -1) {
+      rv = NSRESULT_FOR_ERRNO();
+      break;
+    }
+    target[linkLen] = '\0';
+  }
+
+  free(target);
+
+  if (NS_FAILED(rv)) {
+    aResult.Truncate();
+  }
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetFollowLinks(bool* aFollowLinks)
+{
+  *aFollowLinks = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetFollowLinks(bool aFollowLinks)
+{
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetDirectoryEntries(nsISimpleEnumerator** aEntries)
+{
+  RefPtr<nsDirEnumeratorUnix> dir = new nsDirEnumeratorUnix();
+
+  nsresult rv = dir->Init(this, false);
+  if (NS_FAILED(rv)) {
+    *aEntries = nullptr;
+  } else {
+    dir.forget(aEntries);
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::Load(PRLibrary** aResult)
+{
+  CHECK_mPath();
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+#ifdef NS_BUILD_REFCNT_LOGGING
+  nsTraceRefcnt::SetActivityIsLegal(false);
+#endif
+
+  *aResult = PR_LoadLibrary(mPath.get());
+
+#ifdef NS_BUILD_REFCNT_LOGGING
+  nsTraceRefcnt::SetActivityIsLegal(true);
+#endif
+
+  if (!*aResult) {
+    return NS_ERROR_FAILURE;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetPersistentDescriptor(nsACString& aPersistentDescriptor)
+{
+  return GetNativePath(aPersistentDescriptor);
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetPersistentDescriptor(const nsACString& aPersistentDescriptor)
+{
+#ifdef MOZ_WIDGET_COCOA
+  if (aPersistentDescriptor.IsEmpty()) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // Support pathnames as user-supplied descriptors if they begin with '/'
+  // or '~'.  These characters do not collide with the base64 set used for
+  // encoding alias records.
+  char first = aPersistentDescriptor.First();
+  if (first == '/' || first == '~') {
+    return InitWithNativePath(aPersistentDescriptor);
+  }
+
+  uint32_t dataSize = aPersistentDescriptor.Length();
+  char* decodedData = PL_Base64Decode(
+    PromiseFlatCString(aPersistentDescriptor).get(), dataSize, nullptr);
+  if (!decodedData) {
+    NS_ERROR("SetPersistentDescriptor was given bad data");
+    return NS_ERROR_FAILURE;
+  }
+
+  // Cast to an alias record and resolve.
+  AliasRecord aliasHeader = *(AliasPtr)decodedData;
+  int32_t aliasSize = ::GetAliasSizeFromPtr(&aliasHeader);
+  if (aliasSize > ((int32_t)dataSize * 3) / 4) { // be paranoid about having too few data
+    PR_Free(decodedData);
+    return NS_ERROR_FAILURE;
+  }
+
+  nsresult rv = NS_OK;
+
+  // Move the now-decoded data into the Handle.
+  // The size of the decoded data is 3/4 the size of the encoded data. See plbase64.h
+  Handle  newHandle = nullptr;
+  if (::PtrToHand(decodedData, &newHandle, aliasSize) != noErr) {
+    rv = NS_ERROR_OUT_OF_MEMORY;
+  }
+  PR_Free(decodedData);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  Boolean changed;
+  FSRef resolvedFSRef;
+  OSErr err = ::FSResolveAlias(nullptr, (AliasHandle)newHandle, &resolvedFSRef,
+                               &changed);
+
+  rv = MacErrorMapper(err);
+  DisposeHandle(newHandle);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  return InitWithFSRef(&resolvedFSRef);
+#else
+  return InitWithNativePath(aPersistentDescriptor);
+#endif
+}
+
+NS_IMETHODIMP
+nsLocalFile::Reveal()
+{
+#ifdef MOZ_WIDGET_GTK
+  nsCOMPtr<nsIGIOService> giovfs = do_GetService(NS_GIOSERVICE_CONTRACTID);
+  if (!giovfs) {
+    return NS_ERROR_FAILURE;
+  }
+
+  bool isDirectory;
+  if (NS_FAILED(IsDirectory(&isDirectory))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (isDirectory) {
+    return giovfs->ShowURIForInput(mPath);
+  } else if (NS_SUCCEEDED(giovfs->OrgFreedesktopFileManager1ShowItems(mPath))) {
+    return NS_OK;
+  } else {
+    nsCOMPtr<nsIFile> parentDir;
+    nsAutoCString dirPath;
+    if (NS_FAILED(GetParent(getter_AddRefs(parentDir)))) {
+      return NS_ERROR_FAILURE;
+    }
+    if (NS_FAILED(parentDir->GetNativePath(dirPath))) {
+      return NS_ERROR_FAILURE;
+    }
+
+    return giovfs->ShowURIForInput(dirPath);
+  }
+#elif defined(MOZ_WIDGET_COCOA)
+  CFURLRef url;
+  if (NS_SUCCEEDED(GetCFURL(&url))) {
+    nsresult rv = CocoaFileUtils::RevealFileInFinder(url);
+    ::CFRelease(url);
+    return rv;
+  }
+  return NS_ERROR_FAILURE;
+#else
+  return NS_ERROR_FAILURE;
+#endif
+}
+
+NS_IMETHODIMP
+nsLocalFile::Launch()
+{
+#ifdef MOZ_WIDGET_GTK
+  nsCOMPtr<nsIGIOService> giovfs = do_GetService(NS_GIOSERVICE_CONTRACTID);
+  if (!giovfs) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return giovfs->ShowURIForInput(mPath);
+#elif defined(MOZ_ENABLE_CONTENTACTION)
+  QUrl uri = QUrl::fromLocalFile(QString::fromUtf8(mPath.get()));
+  ContentAction::Action action =
+    ContentAction::Action::defaultActionForFile(uri);
+
+  if (action.isValid()) {
+    action.trigger();
+    return NS_OK;
+  }
+
+  return NS_ERROR_FAILURE;
+#elif defined(MOZ_WIDGET_ANDROID)
+  // Try to get a mimetype, if this fails just use the file uri alone
+  nsresult rv;
+  nsAutoCString type;
+  nsCOMPtr<nsIMIMEService> mimeService(do_GetService("@mozilla.org/mime;1", &rv));
+  if (NS_SUCCEEDED(rv)) {
+    rv = mimeService->GetTypeFromFile(this, type);
+  }
+
+  nsAutoCString fileUri = NS_LITERAL_CSTRING("file://") + mPath;
+  return java::GeckoAppShell::OpenUriExternal(
+    NS_ConvertUTF8toUTF16(fileUri),
+    NS_ConvertUTF8toUTF16(type),
+    EmptyString(),
+    EmptyString(),
+    EmptyString(),
+    EmptyString()) ? NS_OK : NS_ERROR_FAILURE;
+#elif defined(MOZ_WIDGET_COCOA)
+  CFURLRef url;
+  if (NS_SUCCEEDED(GetCFURL(&url))) {
+    nsresult rv = CocoaFileUtils::OpenURL(url);
+    ::CFRelease(url);
+    return rv;
+  }
+  return NS_ERROR_FAILURE;
+#else
+  return NS_ERROR_FAILURE;
+#endif
+}
+
+nsresult
+NS_NewNativeLocalFile(const nsACString& aPath, bool aFollowSymlinks,
+                      nsIFile** aResult)
+{
+  RefPtr<nsLocalFile> file = new nsLocalFile();
+
+  file->SetFollowLinks(aFollowSymlinks);
+
+  if (!aPath.IsEmpty()) {
+    nsresult rv = file->InitWithNativePath(aPath);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+  }
+  file.forget(aResult);
+  return NS_OK;
+}
+
+//-----------------------------------------------------------------------------
+// unicode support
+//-----------------------------------------------------------------------------
+
+#define SET_UCS(func, ucsArg) \
+    { \
+        nsAutoCString buf; \
+        nsresult rv = NS_CopyUnicodeToNative(ucsArg, buf); \
+        if (NS_FAILED(rv)) \
+            return rv; \
+        return (func)(buf); \
+    }
+
+#define GET_UCS(func, ucsArg) \
+    { \
+        nsAutoCString buf; \
+        nsresult rv = (func)(buf); \
+        if (NS_FAILED(rv)) return rv; \
+        return NS_CopyNativeToUnicode(buf, ucsArg); \
+    }
+
+#define SET_UCS_2ARGS_2(func, opaqueArg, ucsArg) \
+    { \
+        nsAutoCString buf; \
+        nsresult rv = NS_CopyUnicodeToNative(ucsArg, buf); \
+        if (NS_FAILED(rv)) \
+            return rv; \
+        return (func)(opaqueArg, buf); \
+    }
+
+// Unicode interface Wrapper
+nsresult
+nsLocalFile::InitWithPath(const nsAString& aFilePath)
+{
+  SET_UCS(InitWithNativePath, aFilePath);
+}
+nsresult
+nsLocalFile::Append(const nsAString& aNode)
+{
+  SET_UCS(AppendNative, aNode);
+}
+nsresult
+nsLocalFile::AppendRelativePath(const nsAString& aNode)
+{
+  SET_UCS(AppendRelativeNativePath, aNode);
+}
+nsresult
+nsLocalFile::GetLeafName(nsAString& aLeafName)
+{
+  GET_UCS(GetNativeLeafName, aLeafName);
+}
+nsresult
+nsLocalFile::SetLeafName(const nsAString& aLeafName)
+{
+  SET_UCS(SetNativeLeafName, aLeafName);
+}
+nsresult
+nsLocalFile::GetPath(nsAString& aResult)
+{
+  return NS_CopyNativeToUnicode(mPath, aResult);
+}
+nsresult
+nsLocalFile::CopyTo(nsIFile* aNewParentDir, const nsAString& aNewName)
+{
+  SET_UCS_2ARGS_2(CopyToNative , aNewParentDir, aNewName);
+}
+nsresult
+nsLocalFile::CopyToFollowingLinks(nsIFile* aNewParentDir,
+                                  const nsAString& aNewName)
+{
+  SET_UCS_2ARGS_2(CopyToFollowingLinksNative , aNewParentDir, aNewName);
+}
+nsresult
+nsLocalFile::MoveTo(nsIFile* aNewParentDir, const nsAString& aNewName)
+{
+  SET_UCS_2ARGS_2(MoveToNative, aNewParentDir, aNewName);
+}
+
+NS_IMETHODIMP
+nsLocalFile::RenameTo(nsIFile* aNewParentDir, const nsAString& aNewName)
+{
+  SET_UCS_2ARGS_2(RenameToNative, aNewParentDir, aNewName);
+}
+
+NS_IMETHODIMP
+nsLocalFile::RenameToNative(nsIFile* aNewParentDir, const nsACString& aNewName)
+{
+  nsresult rv;
+
+  // check to make sure that this has been initialized properly
+  CHECK_mPath();
+
+  // check to make sure that we have a new parent
+  nsAutoCString newPathName;
+  rv = GetNativeTargetPathName(aNewParentDir, aNewName, newPathName);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // try for atomic rename
+  if (rename(mPath.get(), newPathName.get()) < 0) {
+    if (errno == EXDEV) {
+      rv = NS_ERROR_FILE_ACCESS_DENIED;
+    } else {
+      rv = NSRESULT_FOR_ERRNO();
+    }
+  }
+
+  return rv;
+}
+
+nsresult
+nsLocalFile::GetTarget(nsAString& aResult)
+{
+  GET_UCS(GetNativeTarget, aResult);
+}
+
+// nsIHashable
+
+NS_IMETHODIMP
+nsLocalFile::Equals(nsIHashable* aOther, bool* aResult)
+{
+  nsCOMPtr<nsIFile> otherFile(do_QueryInterface(aOther));
+  if (!otherFile) {
+    *aResult = false;
+    return NS_OK;
+  }
+
+  return Equals(otherFile, aResult);
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetHashCode(uint32_t* aResult)
+{
+  *aResult = HashString(mPath);
+  return NS_OK;
+}
+
+nsresult
+NS_NewLocalFile(const nsAString& aPath, bool aFollowLinks, nsIFile** aResult)
+{
+  nsAutoCString buf;
+  nsresult rv = NS_CopyUnicodeToNative(aPath, buf);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  return NS_NewNativeLocalFile(buf, aFollowLinks, aResult);
+}
+
+//-----------------------------------------------------------------------------
+// global init/shutdown
+//-----------------------------------------------------------------------------
+
+void
+nsLocalFile::GlobalInit()
+{
+}
+
+void
+nsLocalFile::GlobalShutdown()
+{
+}
+
+// nsILocalFileMac
+
+#ifdef MOZ_WIDGET_COCOA
+
+static nsresult MacErrorMapper(OSErr inErr)
+{
+  nsresult outErr;
+
+  switch (inErr) {
+    case noErr:
+      outErr = NS_OK;
+      break;
+
+    case fnfErr:
+    case afpObjectNotFound:
+    case afpDirNotFound:
+      outErr = NS_ERROR_FILE_NOT_FOUND;
+      break;
+
+    case dupFNErr:
+    case afpObjectExists:
+      outErr = NS_ERROR_FILE_ALREADY_EXISTS;
+      break;
+
+    case dskFulErr:
+    case afpDiskFull:
+      outErr = NS_ERROR_FILE_DISK_FULL;
+      break;
+
+    case fLckdErr:
+    case afpVolLocked:
+      outErr = NS_ERROR_FILE_IS_LOCKED;
+      break;
+
+    case afpAccessDenied:
+      outErr = NS_ERROR_FILE_ACCESS_DENIED;
+      break;
+
+    case afpDirNotEmpty:
+      outErr = NS_ERROR_FILE_DIR_NOT_EMPTY;
+      break;
+
+    // Can't find good map for some
+    case bdNamErr:
+      outErr = NS_ERROR_FAILURE;
+      break;
+
+    default:
+      outErr = NS_ERROR_FAILURE;
+      break;
+  }
+
+  return outErr;
+}
+
+static nsresult CFStringReftoUTF8(CFStringRef aInStrRef, nsACString& aOutStr)
+{
+  // first see if the conversion would succeed and find the length of the result
+  CFIndex usedBufLen, inStrLen = ::CFStringGetLength(aInStrRef);
+  CFIndex charsConverted = ::CFStringGetBytes(aInStrRef, CFRangeMake(0, inStrLen),
+                                              kCFStringEncodingUTF8, 0, false,
+                                              nullptr, 0, &usedBufLen);
+  if (charsConverted == inStrLen) {
+    // all characters converted, do the actual conversion
+    aOutStr.SetLength(usedBufLen);
+    if (aOutStr.Length() != (unsigned int)usedBufLen) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    UInt8* buffer = (UInt8*)aOutStr.BeginWriting();
+    ::CFStringGetBytes(aInStrRef, CFRangeMake(0, inStrLen), kCFStringEncodingUTF8,
+                       0, false, buffer, usedBufLen, &usedBufLen);
+    return NS_OK;
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsLocalFile::InitWithCFURL(CFURLRef aCFURL)
+{
+  UInt8 path[PATH_MAX];
+  if (::CFURLGetFileSystemRepresentation(aCFURL, true, path, PATH_MAX)) {
+    nsDependentCString nativePath((char*)path);
+    return InitWithNativePath(nativePath);
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsLocalFile::InitWithFSRef(const FSRef* aFSRef)
+{
+  if (NS_WARN_IF(!aFSRef)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  CFURLRef newURLRef = ::CFURLCreateFromFSRef(kCFAllocatorDefault, aFSRef);
+  if (newURLRef) {
+    nsresult rv = InitWithCFURL(newURLRef);
+    ::CFRelease(newURLRef);
+    return rv;
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetCFURL(CFURLRef* aResult)
+{
+  CHECK_mPath();
+
+  bool isDir;
+  IsDirectory(&isDir);
+  *aResult = ::CFURLCreateFromFileSystemRepresentation(kCFAllocatorDefault,
+                                                       (UInt8*)mPath.get(),
+                                                       mPath.Length(),
+                                                       isDir);
+
+  return (*aResult ? NS_OK : NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetFSRef(FSRef* aResult)
+{
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsresult rv = NS_ERROR_FAILURE;
+
+  CFURLRef url = nullptr;
+  if (NS_SUCCEEDED(GetCFURL(&url))) {
+    if (::CFURLGetFSRef(url, aResult)) {
+      rv = NS_OK;
+    }
+    ::CFRelease(url);
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetFSSpec(FSSpec* aResult)
+{
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  FSRef fsRef;
+  nsresult rv = GetFSRef(&fsRef);
+  if (NS_SUCCEEDED(rv)) {
+    OSErr err = ::FSGetCatalogInfo(&fsRef, kFSCatInfoNone, nullptr, nullptr,
+                                   aResult, nullptr);
+    return MacErrorMapper(err);
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetFileSizeWithResFork(int64_t* aFileSizeWithResFork)
+{
+  if (NS_WARN_IF(!aFileSizeWithResFork)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  FSRef fsRef;
+  nsresult rv = GetFSRef(&fsRef);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  FSCatalogInfo catalogInfo;
+  OSErr err = ::FSGetCatalogInfo(&fsRef, kFSCatInfoDataSizes + kFSCatInfoRsrcSizes,
+                                 &catalogInfo, nullptr, nullptr, nullptr);
+  if (err != noErr) {
+    return MacErrorMapper(err);
+  }
+
+  *aFileSizeWithResFork =
+    catalogInfo.dataLogicalSize + catalogInfo.rsrcLogicalSize;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetFileType(OSType* aFileType)
+{
+  CFURLRef url;
+  if (NS_SUCCEEDED(GetCFURL(&url))) {
+    nsresult rv = CocoaFileUtils::GetFileTypeCode(url, aFileType);
+    ::CFRelease(url);
+    return rv;
+  }
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetFileType(OSType aFileType)
+{
+  CFURLRef url;
+  if (NS_SUCCEEDED(GetCFURL(&url))) {
+    nsresult rv = CocoaFileUtils::SetFileTypeCode(url, aFileType);
+    ::CFRelease(url);
+    return rv;
+  }
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetFileCreator(OSType* aFileCreator)
+{
+  CFURLRef url;
+  if (NS_SUCCEEDED(GetCFURL(&url))) {
+    nsresult rv = CocoaFileUtils::GetFileCreatorCode(url, aFileCreator);
+    ::CFRelease(url);
+    return rv;
+  }
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetFileCreator(OSType aFileCreator)
+{
+  CFURLRef url;
+  if (NS_SUCCEEDED(GetCFURL(&url))) {
+    nsresult rv = CocoaFileUtils::SetFileCreatorCode(url, aFileCreator);
+    ::CFRelease(url);
+    return rv;
+  }
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsLocalFile::LaunchWithDoc(nsIFile* aDocToLoad, bool aLaunchInBackground)
+{
+  bool isExecutable;
+  nsresult rv = IsExecutable(&isExecutable);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (!isExecutable) {
+    return NS_ERROR_FILE_EXECUTION_FAILED;
+  }
+
+  FSRef appFSRef, docFSRef;
+  rv = GetFSRef(&appFSRef);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (aDocToLoad) {
+    nsCOMPtr<nsILocalFileMac> macDoc = do_QueryInterface(aDocToLoad);
+    rv = macDoc->GetFSRef(&docFSRef);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+  }
+
+  LSLaunchFlags theLaunchFlags = kLSLaunchDefaults;
+  LSLaunchFSRefSpec thelaunchSpec;
+
+  if (aLaunchInBackground) {
+    theLaunchFlags |= kLSLaunchDontSwitch;
+  }
+  memset(&thelaunchSpec, 0, sizeof(LSLaunchFSRefSpec));
+
+  thelaunchSpec.appRef = &appFSRef;
+  if (aDocToLoad) {
+    thelaunchSpec.numDocs = 1;
+    thelaunchSpec.itemRefs = &docFSRef;
+  }
+  thelaunchSpec.launchFlags = theLaunchFlags;
+
+  OSErr err = ::LSOpenFromRefSpec(&thelaunchSpec, nullptr);
+  if (err != noErr) {
+    return MacErrorMapper(err);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::OpenDocWithApp(nsIFile* aAppToOpenWith, bool aLaunchInBackground)
+{
+  FSRef docFSRef;
+  nsresult rv = GetFSRef(&docFSRef);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (!aAppToOpenWith) {
+    OSErr err = ::LSOpenFSRef(&docFSRef, nullptr);
+    return MacErrorMapper(err);
+  }
+
+  nsCOMPtr<nsILocalFileMac> appFileMac = do_QueryInterface(aAppToOpenWith, &rv);
+  if (!appFileMac) {
+    return rv;
+  }
+
+  bool isExecutable;
+  rv = appFileMac->IsExecutable(&isExecutable);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (!isExecutable) {
+    return NS_ERROR_FILE_EXECUTION_FAILED;
+  }
+
+  FSRef appFSRef;
+  rv = appFileMac->GetFSRef(&appFSRef);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  LSLaunchFlags theLaunchFlags = kLSLaunchDefaults;
+  LSLaunchFSRefSpec thelaunchSpec;
+
+  if (aLaunchInBackground) {
+    theLaunchFlags |= kLSLaunchDontSwitch;
+  }
+  memset(&thelaunchSpec, 0, sizeof(LSLaunchFSRefSpec));
+
+  thelaunchSpec.appRef = &appFSRef;
+  thelaunchSpec.numDocs = 1;
+  thelaunchSpec.itemRefs = &docFSRef;
+  thelaunchSpec.launchFlags = theLaunchFlags;
+
+  OSErr err = ::LSOpenFromRefSpec(&thelaunchSpec, nullptr);
+  if (err != noErr) {
+    return MacErrorMapper(err);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::IsPackage(bool* aResult)
+{
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  *aResult = false;
+
+  CFURLRef url;
+  nsresult rv = GetCFURL(&url);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  LSItemInfoRecord info;
+  OSStatus status = ::LSCopyItemInfoForURL(url, kLSRequestBasicFlagsOnly, &info);
+
+  ::CFRelease(url);
+
+  if (status != noErr) {
+    return NS_ERROR_FAILURE;
+  }
+
+  *aResult = !!(info.flags & kLSItemInfoIsPackage);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetBundleDisplayName(nsAString& aOutBundleName)
+{
+  bool isPackage = false;
+  nsresult rv = IsPackage(&isPackage);
+  if (NS_FAILED(rv) || !isPackage) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsAutoString name;
+  rv = GetLeafName(name);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  int32_t length = name.Length();
+  if (Substring(name, length - 4, length).EqualsLiteral(".app")) {
+    // 4 characters in ".app"
+    aOutBundleName = Substring(name, 0, length - 4);
+  } else {
+    aOutBundleName = name;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetBundleIdentifier(nsACString& aOutBundleIdentifier)
+{
+  nsresult rv = NS_ERROR_FAILURE;
+
+  CFURLRef urlRef;
+  if (NS_SUCCEEDED(GetCFURL(&urlRef))) {
+    CFBundleRef bundle = ::CFBundleCreate(nullptr, urlRef);
+    if (bundle) {
+      CFStringRef bundleIdentifier = ::CFBundleGetIdentifier(bundle);
+      if (bundleIdentifier) {
+        rv = CFStringReftoUTF8(bundleIdentifier, aOutBundleIdentifier);
+      }
+      ::CFRelease(bundle);
+    }
+    ::CFRelease(urlRef);
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetBundleContentsLastModifiedTime(int64_t* aLastModTime)
+{
+  CHECK_mPath();
+  if (NS_WARN_IF(!aLastModTime)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  bool isPackage = false;
+  nsresult rv = IsPackage(&isPackage);
+  if (NS_FAILED(rv) || !isPackage) {
+    return GetLastModifiedTime(aLastModTime);
+  }
+
+  nsAutoCString infoPlistPath(mPath);
+  infoPlistPath.AppendLiteral("/Contents/Info.plist");
+  PRFileInfo64 info;
+  if (PR_GetFileInfo64(infoPlistPath.get(), &info) != PR_SUCCESS) {
+    return GetLastModifiedTime(aLastModTime);
+  }
+  int64_t modTime = int64_t(info.modifyTime);
+  if (modTime == 0) {
+    *aLastModTime = 0;
+  } else {
+    *aLastModTime = modTime / int64_t(PR_USEC_PER_MSEC);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsLocalFile::InitWithFile(nsIFile* aFile)
+{
+  if (NS_WARN_IF(!aFile)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsAutoCString nativePath;
+  nsresult rv = aFile->GetNativePath(nativePath);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  return InitWithNativePath(nativePath);
+}
+
+nsresult
+NS_NewLocalFileWithFSRef(const FSRef* aFSRef, bool aFollowLinks,
+                         nsILocalFileMac** aResult)
+{
+  RefPtr<nsLocalFile> file = new nsLocalFile();
+
+  file->SetFollowLinks(aFollowLinks);
+
+  nsresult rv = file->InitWithFSRef(aFSRef);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  file.forget(aResult);
+  return NS_OK;
+}
+
+nsresult
+NS_NewLocalFileWithCFURL(const CFURLRef aURL, bool aFollowLinks,
+                         nsILocalFileMac** aResult)
+{
+  RefPtr<nsLocalFile> file = new nsLocalFile();
+
+  file->SetFollowLinks(aFollowLinks);
+
+  nsresult rv = file->InitWithCFURL(aURL);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  file.forget(aResult);
+  return NS_OK;
+}
+
+#endif
diff --git a/xpcom/io/nsLocalFileUnix.h b/xpcom/io/nsLocalFileUnix.h
new file mode 100644
index 000000000..9a3e7d6af
--- /dev/null
+++ b/xpcom/io/nsLocalFileUnix.h
@@ -0,0 +1,138 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Implementation of nsIFile for ``Unixy'' systems.
+ */
+
+#ifndef _nsLocalFileUNIX_H_
+#define _nsLocalFileUNIX_H_
+
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "nscore.h"
+#include "nsString.h"
+#include "nsReadableUtils.h"
+#include "nsIHashable.h"
+#include "nsIClassInfoImpl.h"
+#include "mozilla/Attributes.h"
+#ifdef MOZ_WIDGET_COCOA
+#include "nsILocalFileMac.h"
+#endif
+
+/**
+ *  we need these for statfs()
+ */
+#ifdef HAVE_SYS_STATVFS_H
+  #if defined(__osf__) && defined(__DECCXX)
+    extern "C" int statvfs(const char *, struct statvfs *);
+  #endif
+  #include <sys/statvfs.h>
+#endif
+
+#ifdef HAVE_SYS_STATFS_H
+  #include <sys/statfs.h>
+#endif
+
+#ifdef HAVE_SYS_VFS_H
+  #include <sys/vfs.h>
+#endif
+
+#ifdef HAVE_SYS_MOUNT_H
+  #include <sys/param.h>
+  #include <sys/mount.h>
+#endif
+
+#if defined(HAVE_STATVFS64) && (!defined(LINUX) && !defined(__osf__))
+  #define STATFS statvfs64
+  #define F_BSIZE f_frsize
+#elif defined(HAVE_STATVFS) && (!defined(LINUX) && !defined(__osf__))
+  #define STATFS statvfs
+  #define F_BSIZE f_frsize
+#elif defined(HAVE_STATFS64)
+  #define STATFS statfs64
+  #define F_BSIZE f_bsize
+#elif defined(HAVE_STATFS)
+  #define STATFS statfs
+  #define F_BSIZE f_bsize
+#endif
+
+// stat64 and lstat64 are deprecated on OS X. Normal stat and lstat are
+// 64-bit by default on OS X 10.6+.
+#if defined(HAVE_STAT64) && defined(HAVE_LSTAT64) && !defined(XP_DARWIN)
+  #if defined (AIX)
+    #if defined STAT
+      #undef STAT
+    #endif
+  #endif
+  #define STAT stat64
+  #define LSTAT lstat64
+  #define HAVE_STATS64 1
+#else
+  #define STAT stat
+  #define LSTAT lstat
+#endif
+
+
+class nsLocalFile final
+#ifdef MOZ_WIDGET_COCOA
+  : public nsILocalFileMac
+#else
+  : public nsILocalFile
+#endif
+  , public nsIHashable
+{
+public:
+  NS_DEFINE_STATIC_CID_ACCESSOR(NS_LOCAL_FILE_CID)
+
+  nsLocalFile();
+
+  static nsresult nsLocalFileConstructor(nsISupports* aOuter,
+                                         const nsIID& aIID,
+                                         void** aInstancePtr);
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIFILE
+  NS_DECL_NSILOCALFILE
+#ifdef MOZ_WIDGET_COCOA
+  NS_DECL_NSILOCALFILEMAC
+#endif
+  NS_DECL_NSIHASHABLE
+
+public:
+  static void GlobalInit();
+  static void GlobalShutdown();
+
+private:
+  nsLocalFile(const nsLocalFile& aOther);
+  ~nsLocalFile()
+  {
+  }
+
+protected:
+  // This stat cache holds the *last stat* - it does not invalidate.
+  // Call "FillStatCache" whenever you want to stat our file.
+  struct STAT  mCachedStat;
+  nsCString    mPath;
+
+  void LocateNativeLeafName(nsACString::const_iterator&,
+                            nsACString::const_iterator&);
+
+  nsresult CopyDirectoryTo(nsIFile* aNewParent);
+  nsresult CreateAllAncestors(uint32_t aPermissions);
+  nsresult GetNativeTargetPathName(nsIFile* aNewParent,
+                                   const nsACString& aNewName,
+                                   nsACString& aResult);
+
+  bool FillStatCache();
+
+  nsresult CreateAndKeepOpen(uint32_t aType, int aFlags,
+                             uint32_t aPermissions, PRFileDesc** aResult);
+};
+
+#endif /* _nsLocalFileUNIX_H_ */
diff --git a/xpcom/io/nsLocalFileWin.cpp b/xpcom/io/nsLocalFileWin.cpp
new file mode 100644
index 000000000..3a7e570f5
--- /dev/null
+++ b/xpcom/io/nsLocalFileWin.cpp
@@ -0,0 +1,3787 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/UniquePtrExtensions.h"
+#include "mozilla/WindowsVersion.h"
+
+#include "nsCOMPtr.h"
+#include "nsAutoPtr.h"
+#include "nsMemory.h"
+#include "GeckoProfiler.h"
+
+#include "nsLocalFile.h"
+#include "nsIDirectoryEnumerator.h"
+#include "nsNativeCharsetUtils.h"
+
+#include "nsISimpleEnumerator.h"
+#include "nsIComponentManager.h"
+#include "prio.h"
+#include "private/pprio.h"  // To get PR_ImportFile
+#include "prprf.h"
+#include "prmem.h"
+#include "nsHashKeys.h"
+
+#include "nsXPIDLString.h"
+#include "nsReadableUtils.h"
+
+#include <direct.h>
+#include <windows.h>
+#include <shlwapi.h>
+#include <aclapi.h>
+
+#include "shellapi.h"
+#include "shlguid.h"
+
+#include  <io.h>
+#include  <stdio.h>
+#include  <stdlib.h>
+#include  <mbstring.h>
+
+#include "nsXPIDLString.h"
+#include "prproces.h"
+#include "prlink.h"
+
+#include "mozilla/Mutex.h"
+#include "SpecialSystemDirectory.h"
+
+#include "nsTraceRefcnt.h"
+#include "nsXPCOMCIDInternal.h"
+#include "nsThreadUtils.h"
+#include "nsXULAppAPI.h"
+
+#include "nsIWindowMediator.h"
+#include "mozIDOMWindow.h"
+#include "nsPIDOMWindow.h"
+#include "nsIWidget.h"
+#include "mozilla/WidgetUtils.h"
+
+using namespace mozilla;
+
+#define CHECK_mWorkingPath()                    \
+    PR_BEGIN_MACRO                              \
+        if (mWorkingPath.IsEmpty())             \
+            return NS_ERROR_NOT_INITIALIZED;    \
+    PR_END_MACRO
+
+// CopyFileEx only supports unbuffered I/O in Windows Vista and above
+#ifndef COPY_FILE_NO_BUFFERING
+#define COPY_FILE_NO_BUFFERING 0x00001000
+#endif
+
+#ifndef FILE_ATTRIBUTE_NOT_CONTENT_INDEXED
+#define FILE_ATTRIBUTE_NOT_CONTENT_INDEXED  0x00002000
+#endif
+
+#ifndef DRIVE_REMOTE
+#define DRIVE_REMOTE 4
+#endif
+
+static HWND
+GetMostRecentNavigatorHWND()
+{
+  nsresult rv;
+  nsCOMPtr<nsIWindowMediator> winMediator(
+      do_GetService(NS_WINDOWMEDIATOR_CONTRACTID, &rv));
+  if (NS_FAILED(rv)) {
+    return nullptr;
+  }
+
+  nsCOMPtr<mozIDOMWindowProxy> navWin;
+  rv = winMediator->GetMostRecentWindow(u"navigator:browser",
+                                        getter_AddRefs(navWin));
+  if (NS_FAILED(rv) || !navWin) {
+    return nullptr;
+  }
+
+  nsPIDOMWindowOuter* win = nsPIDOMWindowOuter::From(navWin);
+  nsCOMPtr<nsIWidget> widget = widget::WidgetUtils::DOMWindowToWidget(win);
+  if (!widget) {
+    return nullptr;
+  }
+
+  return reinterpret_cast<HWND>(widget->GetNativeData(NS_NATIVE_WINDOW));
+}
+
+
+/**
+ * A runnable to dispatch back to the main thread when
+ * AsyncRevealOperation completes.
+*/
+class AsyncLocalFileWinDone : public Runnable
+{
+public:
+  AsyncLocalFileWinDone() :
+    mWorkerThread(do_GetCurrentThread())
+  {
+    // Objects of this type must only be created on worker threads
+    MOZ_ASSERT(!NS_IsMainThread());
+  }
+
+  NS_IMETHOD Run() override
+  {
+    // This event shuts down the worker thread and so must be main thread.
+    MOZ_ASSERT(NS_IsMainThread());
+
+    // If we don't destroy the thread when we're done with it, it will hang
+    // around forever... and that is bad!
+    mWorkerThread->Shutdown();
+    return NS_OK;
+  }
+
+private:
+  nsCOMPtr<nsIThread> mWorkerThread;
+};
+
+/**
+ * A runnable to dispatch from the main thread when an async operation should
+ * be performed.
+*/
+class AsyncRevealOperation : public Runnable
+{
+public:
+  explicit AsyncRevealOperation(const nsAString& aResolvedPath)
+    : mResolvedPath(aResolvedPath)
+  {
+  }
+
+  NS_IMETHOD Run() override
+  {
+    MOZ_ASSERT(!NS_IsMainThread(),
+               "AsyncRevealOperation should not be run on the main thread!");
+
+    bool doCoUninitialize = SUCCEEDED(
+      CoInitializeEx(nullptr, COINIT_APARTMENTTHREADED | COINIT_DISABLE_OLE1DDE));
+    Reveal();
+    if (doCoUninitialize) {
+      CoUninitialize();
+    }
+
+    // Send the result back to the main thread so that this thread can be
+    // cleanly shut down
+    nsCOMPtr<nsIRunnable> resultrunnable = new AsyncLocalFileWinDone();
+    NS_DispatchToMainThread(resultrunnable);
+    return NS_OK;
+  }
+
+private:
+  // Reveals the path in explorer.
+  nsresult Reveal()
+  {
+    DWORD attributes = GetFileAttributesW(mResolvedPath.get());
+    if (INVALID_FILE_ATTRIBUTES == attributes) {
+      return NS_ERROR_FILE_INVALID_PATH;
+    }
+
+    HRESULT hr;
+    if (attributes & FILE_ATTRIBUTE_DIRECTORY) {
+      // We have a directory so we should open the directory itself.
+      LPITEMIDLIST dir = ILCreateFromPathW(mResolvedPath.get());
+      if (!dir) {
+        return NS_ERROR_FAILURE;
+      }
+
+      LPCITEMIDLIST selection[] = { dir };
+      UINT count = ArrayLength(selection);
+
+      //Perform the open of the directory.
+      hr = SHOpenFolderAndSelectItems(dir, count, selection, 0);
+      CoTaskMemFree(dir);
+    } else {
+      int32_t len = mResolvedPath.Length();
+      // We don't currently handle UNC long paths of the form \\?\ anywhere so
+      // this should be fine.
+      if (len > MAX_PATH) {
+        return NS_ERROR_FILE_INVALID_PATH;
+      }
+      WCHAR parentDirectoryPath[MAX_PATH + 1] = { 0 };
+      wcsncpy(parentDirectoryPath, mResolvedPath.get(), MAX_PATH);
+      PathRemoveFileSpecW(parentDirectoryPath);
+
+      // We have a file so we should open the parent directory.
+      LPITEMIDLIST dir = ILCreateFromPathW(parentDirectoryPath);
+      if (!dir) {
+        return NS_ERROR_FAILURE;
+      }
+
+      // Set the item in the directory to select to the file we want to reveal.
+      LPITEMIDLIST item = ILCreateFromPathW(mResolvedPath.get());
+      if (!item) {
+        CoTaskMemFree(dir);
+        return NS_ERROR_FAILURE;
+      }
+
+      LPCITEMIDLIST selection[] = { item };
+      UINT count = ArrayLength(selection);
+
+      //Perform the selection of the file.
+      hr = SHOpenFolderAndSelectItems(dir, count, selection, 0);
+
+      CoTaskMemFree(dir);
+      CoTaskMemFree(item);
+    }
+
+    return SUCCEEDED(hr) ? NS_OK : NS_ERROR_FAILURE;
+  }
+
+  // Stores the path to perform the operation on
+  nsString mResolvedPath;
+};
+
+class nsDriveEnumerator : public nsISimpleEnumerator
+{
+public:
+  nsDriveEnumerator();
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISIMPLEENUMERATOR
+  nsresult Init();
+private:
+  virtual ~nsDriveEnumerator();
+
+  /* mDrives stores the null-separated drive names.
+   * Init sets them.
+   * HasMoreElements checks mStartOfCurrentDrive.
+   * GetNext advances mStartOfCurrentDrive.
+   */
+  nsString mDrives;
+  nsAString::const_iterator mStartOfCurrentDrive;
+  nsAString::const_iterator mEndOfDrivesString;
+};
+
+//----------------------------------------------------------------------------
+// short cut resolver
+//----------------------------------------------------------------------------
+class ShortcutResolver
+{
+public:
+  ShortcutResolver();
+  // nonvirtual since we're not subclassed
+  ~ShortcutResolver();
+
+  nsresult Init();
+  nsresult Resolve(const WCHAR* aIn, WCHAR* aOut);
+  nsresult SetShortcut(bool aUpdateExisting,
+                       const WCHAR* aShortcutPath,
+                       const WCHAR* aTargetPath,
+                       const WCHAR* aWorkingDir,
+                       const WCHAR* aArgs,
+                       const WCHAR* aDescription,
+                       const WCHAR* aIconFile,
+                       int32_t aIconIndex);
+
+private:
+  Mutex                  mLock;
+  RefPtr<IPersistFile> mPersistFile;
+  RefPtr<IShellLinkW>  mShellLink;
+};
+
+ShortcutResolver::ShortcutResolver() :
+  mLock("ShortcutResolver.mLock")
+{
+  CoInitialize(nullptr);
+}
+
+ShortcutResolver::~ShortcutResolver()
+{
+  CoUninitialize();
+}
+
+nsresult
+ShortcutResolver::Init()
+{
+  // Get a pointer to the IPersistFile interface.
+  if (FAILED(CoCreateInstance(CLSID_ShellLink,
+                              nullptr,
+                              CLSCTX_INPROC_SERVER,
+                              IID_IShellLinkW,
+                              getter_AddRefs(mShellLink))) ||
+      FAILED(mShellLink->QueryInterface(IID_IPersistFile,
+                                        getter_AddRefs(mPersistFile)))) {
+    mShellLink = nullptr;
+    return NS_ERROR_FAILURE;
+  }
+  return NS_OK;
+}
+
+// |out| must be an allocated buffer of size MAX_PATH
+nsresult
+ShortcutResolver::Resolve(const WCHAR* aIn, WCHAR* aOut)
+{
+  if (!mShellLink) {
+    return NS_ERROR_FAILURE;
+  }
+
+  MutexAutoLock lock(mLock);
+
+  if (FAILED(mPersistFile->Load(aIn, STGM_READ)) ||
+      FAILED(mShellLink->Resolve(nullptr, SLR_NO_UI)) ||
+      FAILED(mShellLink->GetPath(aOut, MAX_PATH, nullptr, SLGP_UNCPRIORITY))) {
+    return NS_ERROR_FAILURE;
+  }
+  return NS_OK;
+}
+
+nsresult
+ShortcutResolver::SetShortcut(bool aUpdateExisting,
+                              const WCHAR* aShortcutPath,
+                              const WCHAR* aTargetPath,
+                              const WCHAR* aWorkingDir,
+                              const WCHAR* aArgs,
+                              const WCHAR* aDescription,
+                              const WCHAR* aIconPath,
+                              int32_t aIconIndex)
+{
+  if (!mShellLink) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (!aShortcutPath) {
+    return NS_ERROR_FAILURE;
+  }
+
+  MutexAutoLock lock(mLock);
+
+  if (aUpdateExisting) {
+    if (FAILED(mPersistFile->Load(aShortcutPath, STGM_READWRITE))) {
+      return NS_ERROR_FAILURE;
+    }
+  } else {
+    if (!aTargetPath) {
+      return NS_ERROR_FILE_TARGET_DOES_NOT_EXIST;
+    }
+
+    // Since we reuse our IPersistFile, we have to clear out any values that
+    // may be left over from previous calls to SetShortcut.
+    if (FAILED(mShellLink->SetWorkingDirectory(L"")) ||
+        FAILED(mShellLink->SetArguments(L"")) ||
+        FAILED(mShellLink->SetDescription(L"")) ||
+        FAILED(mShellLink->SetIconLocation(L"", 0))) {
+      return NS_ERROR_FAILURE;
+    }
+  }
+
+  if (aTargetPath && FAILED(mShellLink->SetPath(aTargetPath))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (aWorkingDir && FAILED(mShellLink->SetWorkingDirectory(aWorkingDir))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (aArgs && FAILED(mShellLink->SetArguments(aArgs))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (aDescription && FAILED(mShellLink->SetDescription(aDescription))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (aIconPath && FAILED(mShellLink->SetIconLocation(aIconPath, aIconIndex))) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (FAILED(mPersistFile->Save(aShortcutPath,
+                                TRUE))) {
+    // Second argument indicates whether the file path specified in the
+    // first argument should become the "current working file" for this
+    // IPersistFile
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+static ShortcutResolver* gResolver = nullptr;
+
+static nsresult
+NS_CreateShortcutResolver()
+{
+  gResolver = new ShortcutResolver();
+  return gResolver->Init();
+}
+
+static void
+NS_DestroyShortcutResolver()
+{
+  delete gResolver;
+  gResolver = nullptr;
+}
+
+
+//-----------------------------------------------------------------------------
+// static helper functions
+//-----------------------------------------------------------------------------
+
+// certainly not all the error that can be
+// encountered, but many of them common ones
+static nsresult
+ConvertWinError(DWORD aWinErr)
+{
+  nsresult rv;
+
+  switch (aWinErr) {
+    case ERROR_FILE_NOT_FOUND:
+    case ERROR_PATH_NOT_FOUND:
+    case ERROR_INVALID_DRIVE:
+    case ERROR_NOT_READY:
+      rv = NS_ERROR_FILE_NOT_FOUND;
+      break;
+    case ERROR_ACCESS_DENIED:
+    case ERROR_NOT_SAME_DEVICE:
+      rv = NS_ERROR_FILE_ACCESS_DENIED;
+      break;
+    case ERROR_SHARING_VIOLATION: // CreateFile without sharing flags
+    case ERROR_LOCK_VIOLATION: // LockFile, LockFileEx
+      rv = NS_ERROR_FILE_IS_LOCKED;
+      break;
+    case ERROR_NOT_ENOUGH_MEMORY:
+    case ERROR_INVALID_BLOCK:
+    case ERROR_INVALID_HANDLE:
+    case ERROR_ARENA_TRASHED:
+      rv = NS_ERROR_OUT_OF_MEMORY;
+      break;
+    case ERROR_CURRENT_DIRECTORY:
+      rv = NS_ERROR_FILE_DIR_NOT_EMPTY;
+      break;
+    case ERROR_WRITE_PROTECT:
+      rv = NS_ERROR_FILE_READ_ONLY;
+      break;
+    case ERROR_HANDLE_DISK_FULL:
+      rv = NS_ERROR_FILE_TOO_BIG;
+      break;
+    case ERROR_FILE_EXISTS:
+    case ERROR_ALREADY_EXISTS:
+    case ERROR_CANNOT_MAKE:
+      rv = NS_ERROR_FILE_ALREADY_EXISTS;
+      break;
+    case ERROR_FILENAME_EXCED_RANGE:
+      rv = NS_ERROR_FILE_NAME_TOO_LONG;
+      break;
+    case ERROR_DIRECTORY:
+      rv = NS_ERROR_FILE_NOT_DIRECTORY;
+      break;
+    case 0:
+      rv = NS_OK;
+      break;
+    default:
+      rv = NS_ERROR_FAILURE;
+      break;
+  }
+  return rv;
+}
+
+// as suggested in the MSDN documentation on SetFilePointer
+static __int64
+MyFileSeek64(HANDLE aHandle, __int64 aDistance, DWORD aMoveMethod)
+{
+  LARGE_INTEGER li;
+
+  li.QuadPart = aDistance;
+  li.LowPart = SetFilePointer(aHandle, li.LowPart, &li.HighPart, aMoveMethod);
+  if (li.LowPart == INVALID_SET_FILE_POINTER && GetLastError() != NO_ERROR) {
+    li.QuadPart = -1;
+  }
+
+  return li.QuadPart;
+}
+
+static bool
+IsShortcutPath(const nsAString& aPath)
+{
+  // Under Windows, the shortcuts are just files with a ".lnk" extension.
+  // Note also that we don't resolve links in the middle of paths.
+  // i.e. "c:\foo.lnk\bar.txt" is invalid.
+  MOZ_ASSERT(!aPath.IsEmpty(), "don't pass an empty string");
+  int32_t len = aPath.Length();
+  return len >= 4 && (StringTail(aPath, 4).LowerCaseEqualsASCII(".lnk"));
+}
+
+//-----------------------------------------------------------------------------
+// We need the following three definitions to make |OpenFile| convert a file
+// handle to an NSPR file descriptor correctly when |O_APPEND| flag is
+// specified. It is defined in a private header of NSPR (primpl.h) we can't
+// include. As a temporary workaround until we decide how to extend
+// |PR_ImportFile|, we define it here. Currently, |_PR_HAVE_PEEK_BUFFER|
+// and |PR_STRICT_ADDR_LEN| are not defined for the 'w95'-dependent portion
+// of NSPR so that fields of |PRFilePrivate| #ifdef'd by them are not copied.
+// Similarly, |_MDFileDesc| is taken from nsprpub/pr/include/md/_win95.h.
+// In an unlikely case we switch to 'NT'-dependent NSPR AND this temporary
+// workaround last beyond the switch, |PRFilePrivate| and |_MDFileDesc|
+// need to be changed to match the definitions for WinNT.
+//-----------------------------------------------------------------------------
+typedef enum
+{
+  _PR_TRI_TRUE = 1,
+  _PR_TRI_FALSE = 0,
+  _PR_TRI_UNKNOWN = -1
+} _PRTriStateBool;
+
+struct _MDFileDesc
+{
+  PROsfd osfd;
+};
+
+struct PRFilePrivate
+{
+  int32_t state;
+  bool nonblocking;
+  _PRTriStateBool inheritable;
+  PRFileDesc* next;
+  int lockCount;      /*   0: not locked
+                       *  -1: a native lockfile call is in progress
+                       * > 0: # times the file is locked */
+  bool    appendMode;
+  _MDFileDesc md;
+};
+
+//-----------------------------------------------------------------------------
+// Six static methods defined below (OpenFile,  FileTimeToPRTime, GetFileInfo,
+// OpenDir, CloseDir, ReadDir) should go away once the corresponding
+// UTF-16 APIs are implemented on all the supported platforms (or at least
+// Windows 9x/ME) in NSPR. Currently, they're only implemented on
+// Windows NT4 or later. (bug 330665)
+//-----------------------------------------------------------------------------
+
+// copied from nsprpub/pr/src/{io/prfile.c | md/windows/w95io.c} :
+// PR_Open and _PR_MD_OPEN
+nsresult
+OpenFile(const nsAFlatString& aName,
+         int aOsflags,
+         int aMode,
+         bool aShareDelete,
+         PRFileDesc** aFd)
+{
+  int32_t access = 0;
+
+  int32_t shareMode = FILE_SHARE_READ | FILE_SHARE_WRITE;
+  int32_t disposition = 0;
+  int32_t attributes = 0;
+
+  if (aShareDelete) {
+    shareMode |= FILE_SHARE_DELETE;
+  }
+
+  if (aOsflags & PR_SYNC) {
+    attributes = FILE_FLAG_WRITE_THROUGH;
+  }
+  if (aOsflags & PR_RDONLY || aOsflags & PR_RDWR) {
+    access |= GENERIC_READ;
+  }
+  if (aOsflags & PR_WRONLY || aOsflags & PR_RDWR) {
+    access |= GENERIC_WRITE;
+  }
+
+  if (aOsflags & PR_CREATE_FILE && aOsflags & PR_EXCL) {
+    disposition = CREATE_NEW;
+  } else if (aOsflags & PR_CREATE_FILE) {
+    if (aOsflags & PR_TRUNCATE) {
+      disposition = CREATE_ALWAYS;
+    } else {
+      disposition = OPEN_ALWAYS;
+    }
+  } else {
+    if (aOsflags & PR_TRUNCATE) {
+      disposition = TRUNCATE_EXISTING;
+    } else {
+      disposition = OPEN_EXISTING;
+    }
+  }
+
+  if (aOsflags & nsIFile::DELETE_ON_CLOSE) {
+    attributes |= FILE_FLAG_DELETE_ON_CLOSE;
+  }
+
+  if (aOsflags & nsIFile::OS_READAHEAD) {
+    attributes |= FILE_FLAG_SEQUENTIAL_SCAN;
+  }
+
+  // If no write permissions are requested, and if we are possibly creating
+  // the file, then set the new file as read only.
+  // The flag has no effect if we happen to open the file.
+  if (!(aMode & (PR_IWUSR | PR_IWGRP | PR_IWOTH)) &&
+      disposition != OPEN_EXISTING) {
+    attributes |= FILE_ATTRIBUTE_READONLY;
+  }
+
+  HANDLE file = ::CreateFileW(aName.get(), access, shareMode,
+                              nullptr, disposition, attributes, nullptr);
+
+  if (file == INVALID_HANDLE_VALUE) {
+    *aFd = nullptr;
+    return ConvertWinError(GetLastError());
+  }
+
+  *aFd = PR_ImportFile((PROsfd) file);
+  if (*aFd) {
+    // On Windows, _PR_HAVE_O_APPEND is not defined so that we have to
+    // add it manually. (see |PR_Open| in nsprpub/pr/src/io/prfile.c)
+    (*aFd)->secret->appendMode = (PR_APPEND & aOsflags) ? true : false;
+    return NS_OK;
+  }
+
+  nsresult rv = NS_ErrorAccordingToNSPR();
+
+  CloseHandle(file);
+
+  return rv;
+}
+
+// copied from nsprpub/pr/src/{io/prfile.c | md/windows/w95io.c} :
+// PR_FileTimeToPRTime and _PR_FileTimeToPRTime
+static void
+FileTimeToPRTime(const FILETIME* aFiletime, PRTime* aPrtm)
+{
+#ifdef __GNUC__
+  const PRTime _pr_filetime_offset = 116444736000000000LL;
+#else
+  const PRTime _pr_filetime_offset = 116444736000000000i64;
+#endif
+
+  MOZ_ASSERT(sizeof(FILETIME) == sizeof(PRTime));
+  ::CopyMemory(aPrtm, aFiletime, sizeof(PRTime));
+#ifdef __GNUC__
+  *aPrtm = (*aPrtm - _pr_filetime_offset) / 10LL;
+#else
+  *aPrtm = (*aPrtm - _pr_filetime_offset) / 10i64;
+#endif
+}
+
+// copied from nsprpub/pr/src/{io/prfile.c | md/windows/w95io.c} with some
+// changes : PR_GetFileInfo64, _PR_MD_GETFILEINFO64
+static nsresult
+GetFileInfo(const nsAFlatString& aName, PRFileInfo64* aInfo)
+{
+  WIN32_FILE_ATTRIBUTE_DATA fileData;
+
+  if (aName.IsEmpty() || aName.FindCharInSet(u"?*") != kNotFound) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  if (!::GetFileAttributesExW(aName.get(), GetFileExInfoStandard, &fileData)) {
+    return ConvertWinError(GetLastError());
+  }
+
+  if (fileData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
+    aInfo->type = PR_FILE_DIRECTORY;
+  } else {
+    aInfo->type = PR_FILE_FILE;
+  }
+
+  aInfo->size = fileData.nFileSizeHigh;
+  aInfo->size = (aInfo->size << 32) + fileData.nFileSizeLow;
+
+  FileTimeToPRTime(&fileData.ftLastWriteTime, &aInfo->modifyTime);
+
+  if (0 == fileData.ftCreationTime.dwLowDateTime &&
+      0 == fileData.ftCreationTime.dwHighDateTime) {
+    aInfo->creationTime = aInfo->modifyTime;
+  } else {
+    FileTimeToPRTime(&fileData.ftCreationTime, &aInfo->creationTime);
+  }
+
+  return NS_OK;
+}
+
+struct nsDir
+{
+  HANDLE handle;
+  WIN32_FIND_DATAW data;
+  bool firstEntry;
+};
+
+static nsresult
+OpenDir(const nsAFlatString& aName, nsDir** aDir)
+{
+  if (NS_WARN_IF(!aDir)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  *aDir = nullptr;
+  if (aName.Length() + 3 >= MAX_PATH) {
+    return NS_ERROR_FILE_NAME_TOO_LONG;
+  }
+
+  nsDir* d  = new nsDir();
+  nsAutoString filename(aName);
+
+  // If |aName| ends in a slash or backslash, do not append another backslash.
+  if (filename.Last() == L'/' || filename.Last() == L'\\') {
+    filename.Append('*');
+  } else {
+    filename.AppendLiteral("\\*");
+  }
+
+  filename.ReplaceChar(L'/', L'\\');
+
+  // FindFirstFileW Will have a last error of ERROR_DIRECTORY if
+  // <file_path>\* is passed in.  If <unknown_path>\* is passed in then
+  // ERROR_PATH_NOT_FOUND will be the last error.
+  d->handle = ::FindFirstFileW(filename.get(), &(d->data));
+
+  if (d->handle == INVALID_HANDLE_VALUE) {
+    delete d;
+    return ConvertWinError(GetLastError());
+  }
+  d->firstEntry = true;
+
+  *aDir = d;
+  return NS_OK;
+}
+
+static nsresult
+ReadDir(nsDir* aDir, PRDirFlags aFlags, nsString& aName)
+{
+  aName.Truncate();
+  if (NS_WARN_IF(!aDir)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  while (1) {
+    BOOL rv;
+    if (aDir->firstEntry) {
+      aDir->firstEntry = false;
+      rv = 1;
+    } else {
+      rv = ::FindNextFileW(aDir->handle, &(aDir->data));
+    }
+
+    if (rv == 0) {
+      break;
+    }
+
+    const wchar_t* fileName;
+    fileName = (aDir)->data.cFileName;
+
+    if ((aFlags & PR_SKIP_DOT) &&
+        (fileName[0] == L'.') && (fileName[1] == L'\0')) {
+      continue;
+    }
+    if ((aFlags & PR_SKIP_DOT_DOT) &&
+        (fileName[0] == L'.') && (fileName[1] == L'.') &&
+        (fileName[2] == L'\0')) {
+      continue;
+    }
+
+    DWORD attrib =  aDir->data.dwFileAttributes;
+    if ((aFlags & PR_SKIP_HIDDEN) && (attrib & FILE_ATTRIBUTE_HIDDEN)) {
+      continue;
+    }
+
+    aName = fileName;
+    return NS_OK;
+  }
+
+  DWORD err = GetLastError();
+  return err == ERROR_NO_MORE_FILES ? NS_OK : ConvertWinError(err);
+}
+
+static nsresult
+CloseDir(nsDir*& aDir)
+{
+  if (NS_WARN_IF(!aDir)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  BOOL isOk = FindClose(aDir->handle);
+  delete aDir;
+  aDir = nullptr;
+  return isOk ? NS_OK : ConvertWinError(GetLastError());
+}
+
+//-----------------------------------------------------------------------------
+// nsDirEnumerator
+//-----------------------------------------------------------------------------
+
+class nsDirEnumerator final
+  : public nsISimpleEnumerator
+  , public nsIDirectoryEnumerator
+{
+private:
+  ~nsDirEnumerator()
+  {
+    Close();
+  }
+
+public:
+  NS_DECL_ISUPPORTS
+
+  nsDirEnumerator() : mDir(nullptr)
+  {
+  }
+
+  nsresult Init(nsIFile* aParent)
+  {
+    nsAutoString filepath;
+    aParent->GetTarget(filepath);
+
+    if (filepath.IsEmpty()) {
+      aParent->GetPath(filepath);
+    }
+
+    if (filepath.IsEmpty()) {
+      return NS_ERROR_UNEXPECTED;
+    }
+
+    // IsDirectory is not needed here because OpenDir will return
+    // NS_ERROR_FILE_NOT_DIRECTORY if the passed in path is a file.
+    nsresult rv = OpenDir(filepath, &mDir);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    mParent = aParent;
+    return NS_OK;
+  }
+
+  NS_IMETHOD HasMoreElements(bool* aResult)
+  {
+    nsresult rv;
+    if (!mNext && mDir) {
+      nsString name;
+      rv = ReadDir(mDir, PR_SKIP_BOTH, name);
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+      if (name.IsEmpty()) {
+        // end of dir entries
+        if (NS_FAILED(CloseDir(mDir))) {
+          return NS_ERROR_FAILURE;
+        }
+
+        *aResult = false;
+        return NS_OK;
+      }
+
+      nsCOMPtr<nsIFile> file;
+      rv = mParent->Clone(getter_AddRefs(file));
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+
+      rv = file->Append(name);
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+
+      mNext = do_QueryInterface(file);
+    }
+    *aResult = mNext != nullptr;
+    if (!*aResult) {
+      Close();
+    }
+    return NS_OK;
+  }
+
+  NS_IMETHOD GetNext(nsISupports** aResult)
+  {
+    nsresult rv;
+    bool hasMore;
+    rv = HasMoreElements(&hasMore);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    *aResult = mNext;        // might return nullptr
+    NS_IF_ADDREF(*aResult);
+
+    mNext = nullptr;
+    return NS_OK;
+  }
+
+  NS_IMETHOD GetNextFile(nsIFile** aResult)
+  {
+    *aResult = nullptr;
+    bool hasMore = false;
+    nsresult rv = HasMoreElements(&hasMore);
+    if (NS_FAILED(rv) || !hasMore) {
+      return rv;
+    }
+    *aResult = mNext;
+    NS_IF_ADDREF(*aResult);
+    mNext = nullptr;
+    return NS_OK;
+  }
+
+  NS_IMETHOD Close()
+  {
+    if (mDir) {
+      nsresult rv = CloseDir(mDir);
+      NS_ASSERTION(NS_SUCCEEDED(rv), "close failed");
+      if (NS_FAILED(rv)) {
+        return NS_ERROR_FAILURE;
+      }
+    }
+    return NS_OK;
+  }
+
+protected:
+  nsDir*             mDir;
+  nsCOMPtr<nsIFile>  mParent;
+  nsCOMPtr<nsIFile>  mNext;
+};
+
+NS_IMPL_ISUPPORTS(nsDirEnumerator, nsISimpleEnumerator, nsIDirectoryEnumerator)
+
+
+//-----------------------------------------------------------------------------
+// nsLocalFile <public>
+//-----------------------------------------------------------------------------
+
+nsLocalFile::nsLocalFile()
+  : mDirty(true)
+  , mResolveDirty(true)
+  , mFollowSymlinks(false)
+{
+}
+
+nsresult
+nsLocalFile::nsLocalFileConstructor(nsISupports* aOuter, const nsIID& aIID,
+                                    void** aInstancePtr)
+{
+  if (NS_WARN_IF(!aInstancePtr)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  if (NS_WARN_IF(aOuter)) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+
+  nsLocalFile* inst = new nsLocalFile();
+  nsresult rv = inst->QueryInterface(aIID, aInstancePtr);
+  if (NS_FAILED(rv)) {
+    delete inst;
+    return rv;
+  }
+  return NS_OK;
+}
+
+
+//-----------------------------------------------------------------------------
+// nsLocalFile::nsISupports
+//-----------------------------------------------------------------------------
+
+NS_IMPL_ISUPPORTS(nsLocalFile,
+                  nsILocalFile,
+                  nsIFile,
+                  nsILocalFileWin,
+                  nsIHashable)
+
+
+//-----------------------------------------------------------------------------
+// nsLocalFile <private>
+//-----------------------------------------------------------------------------
+
+nsLocalFile::nsLocalFile(const nsLocalFile& aOther)
+  : mDirty(true)
+  , mResolveDirty(true)
+  , mFollowSymlinks(aOther.mFollowSymlinks)
+  , mWorkingPath(aOther.mWorkingPath)
+{
+}
+
+// Resolve the shortcut file from mWorkingPath and write the path
+// it points to into mResolvedPath.
+nsresult
+nsLocalFile::ResolveShortcut()
+{
+  // we can't do anything without the resolver
+  if (!gResolver) {
+    return NS_ERROR_FAILURE;
+  }
+
+  mResolvedPath.SetLength(MAX_PATH);
+  if (mResolvedPath.Length() != MAX_PATH) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  wchar_t* resolvedPath = wwc(mResolvedPath.BeginWriting());
+
+  // resolve this shortcut
+  nsresult rv = gResolver->Resolve(mWorkingPath.get(), resolvedPath);
+
+  size_t len = NS_FAILED(rv) ? 0 : wcslen(resolvedPath);
+  mResolvedPath.SetLength(len);
+
+  return rv;
+}
+
+// Resolve any shortcuts and stat the resolved path. After a successful return
+// the path is guaranteed valid and the members of mFileInfo64 can be used.
+nsresult
+nsLocalFile::ResolveAndStat()
+{
+  // if we aren't dirty then we are already done
+  if (!mDirty) {
+    return NS_OK;
+  }
+
+  PROFILER_LABEL_FUNC(js::ProfileEntry::Category::OTHER);
+  // we can't resolve/stat anything that isn't a valid NSPR addressable path
+  if (mWorkingPath.IsEmpty()) {
+    return NS_ERROR_FILE_INVALID_PATH;
+  }
+
+  // this is usually correct
+  mResolvedPath.Assign(mWorkingPath);
+
+  // slutty hack designed to work around bug 134796 until it is fixed
+  nsAutoString nsprPath(mWorkingPath.get());
+  if (mWorkingPath.Length() == 2 && mWorkingPath.CharAt(1) == L':') {
+    nsprPath.Append('\\');
+  }
+
+  // first we will see if the working path exists. If it doesn't then
+  // there is nothing more that can be done
+  nsresult rv = GetFileInfo(nsprPath, &mFileInfo64);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // if this isn't a shortcut file or we aren't following symlinks then we're done
+  if (!mFollowSymlinks ||
+      mFileInfo64.type != PR_FILE_FILE ||
+      !IsShortcutPath(mWorkingPath)) {
+    mDirty = false;
+    mResolveDirty = false;
+    return NS_OK;
+  }
+
+  // we need to resolve this shortcut to what it points to, this will
+  // set mResolvedPath. Even if it fails we need to have the resolved
+  // path equal to working path for those functions that always use
+  // the resolved path.
+  rv = ResolveShortcut();
+  if (NS_FAILED(rv)) {
+    mResolvedPath.Assign(mWorkingPath);
+    return rv;
+  }
+  mResolveDirty = false;
+
+  // get the details of the resolved path
+  rv = GetFileInfo(mResolvedPath, &mFileInfo64);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  mDirty = false;
+  return NS_OK;
+}
+
+/**
+ * Fills the mResolvedPath member variable with the file or symlink target
+ * if follow symlinks is on.  This is a copy of the Resolve parts from
+ * ResolveAndStat. ResolveAndStat is much slower though because of the stat.
+ *
+ * @return NS_OK on success.
+*/
+nsresult
+nsLocalFile::Resolve()
+{
+  // if we aren't dirty then we are already done
+  if (!mResolveDirty) {
+    return NS_OK;
+  }
+
+  // we can't resolve/stat anything that isn't a valid NSPR addressable path
+  if (mWorkingPath.IsEmpty()) {
+    return NS_ERROR_FILE_INVALID_PATH;
+  }
+
+  // this is usually correct
+  mResolvedPath.Assign(mWorkingPath);
+
+  // if this isn't a shortcut file or we aren't following symlinks then
+  // we're done.
+  if (!mFollowSymlinks ||
+      !IsShortcutPath(mWorkingPath)) {
+    mResolveDirty = false;
+    return NS_OK;
+  }
+
+  // we need to resolve this shortcut to what it points to, this will
+  // set mResolvedPath. Even if it fails we need to have the resolved
+  // path equal to working path for those functions that always use
+  // the resolved path.
+  nsresult rv = ResolveShortcut();
+  if (NS_FAILED(rv)) {
+    mResolvedPath.Assign(mWorkingPath);
+    return rv;
+  }
+
+  mResolveDirty = false;
+  return NS_OK;
+}
+
+//-----------------------------------------------------------------------------
+// nsLocalFile::nsIFile,nsILocalFile
+//-----------------------------------------------------------------------------
+
+NS_IMETHODIMP
+nsLocalFile::Clone(nsIFile** aFile)
+{
+  // Just copy-construct ourselves
+  RefPtr<nsLocalFile> file = new nsLocalFile(*this);
+  file.forget(aFile);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::InitWithFile(nsIFile* aFile)
+{
+  if (NS_WARN_IF(!aFile)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsAutoString path;
+  aFile->GetPath(path);
+  if (path.IsEmpty()) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  return InitWithPath(path);
+}
+
+NS_IMETHODIMP
+nsLocalFile::InitWithPath(const nsAString& aFilePath)
+{
+  MakeDirty();
+
+  nsAString::const_iterator begin, end;
+  aFilePath.BeginReading(begin);
+  aFilePath.EndReading(end);
+
+  // input string must not be empty
+  if (begin == end) {
+    return NS_ERROR_FAILURE;
+  }
+
+  char16_t firstChar = *begin;
+  char16_t secondChar = *(++begin);
+
+  // just do a sanity check.  if it has any forward slashes, it is not a Native path
+  // on windows.  Also, it must have a colon at after the first char.
+  if (FindCharInReadable(L'/', begin, end)) {
+    return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+  }
+
+  if (secondChar != L':' && (secondChar != L'\\' || firstChar != L'\\')) {
+    return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+  }
+
+  if (secondChar == L':') {
+    // Make sure we have a valid drive, later code assumes the drive letter
+    // is a single char a-z or A-Z.
+    if (PathGetDriveNumberW(aFilePath.Data()) == -1) {
+      return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+    }
+  }
+
+  mWorkingPath = aFilePath;
+  // kill any trailing '\'
+  if (mWorkingPath.Last() == L'\\') {
+    mWorkingPath.Truncate(mWorkingPath.Length() - 1);
+  }
+
+  return NS_OK;
+
+}
+
+// Strip a handler command string of its quotes and parameters.
+static void
+CleanupHandlerPath(nsString& aPath)
+{
+  // Example command strings passed into this routine:
+
+  // 1) C:\Program Files\Company\some.exe -foo -bar
+  // 2) C:\Program Files\Company\some.dll
+  // 3) C:\Windows\some.dll,-foo -bar
+  // 4) C:\Windows\some.cpl,-foo -bar
+
+  int32_t lastCommaPos = aPath.RFindChar(',');
+  if (lastCommaPos != kNotFound)
+    aPath.Truncate(lastCommaPos);
+
+  aPath.Append(' ');
+
+  // case insensitive
+  uint32_t index = aPath.Find(".exe ", true);
+  if (index == kNotFound)
+    index = aPath.Find(".dll ", true);
+  if (index == kNotFound)
+    index = aPath.Find(".cpl ", true);
+
+  if (index != kNotFound)
+    aPath.Truncate(index + 4);
+  aPath.Trim(" ", true, true);
+}
+
+// Strip the windows host process bootstrap executable rundll32.exe
+// from a handler's command string if it exists.
+static void
+StripRundll32(nsString& aCommandString)
+{
+  // Example rundll formats:
+  // C:\Windows\System32\rundll32.exe "path to dll"
+  // rundll32.exe "path to dll"
+  // C:\Windows\System32\rundll32.exe "path to dll", var var
+  // rundll32.exe "path to dll", var var
+
+  NS_NAMED_LITERAL_STRING(rundllSegment, "rundll32.exe ");
+  NS_NAMED_LITERAL_STRING(rundllSegmentShort, "rundll32 ");
+
+  // case insensitive
+  int32_t strLen = rundllSegment.Length();
+  int32_t index = aCommandString.Find(rundllSegment, true);
+  if (index == kNotFound) {
+    strLen = rundllSegmentShort.Length();
+    index = aCommandString.Find(rundllSegmentShort, true);
+  }
+
+  if (index != kNotFound) {
+    uint32_t rundllSegmentLength = index + strLen;
+    aCommandString.Cut(0, rundllSegmentLength);
+  }
+}
+
+// Returns the fully qualified path to an application handler based on
+// a parameterized command string. Note this routine should not be used
+// to launch the associated application as it strips parameters and
+// rundll.exe from the string. Designed for retrieving display information
+// on a particular handler.
+/* static */ bool
+nsLocalFile::CleanupCmdHandlerPath(nsAString& aCommandHandler)
+{
+  nsAutoString handlerCommand(aCommandHandler);
+
+  // Straight command path:
+  //
+  // %SystemRoot%\system32\NOTEPAD.EXE var
+  // "C:\Program Files\iTunes\iTunes.exe" var var
+  // C:\Program Files\iTunes\iTunes.exe var var
+  //
+  // Example rundll handlers:
+  //
+  // rundll32.exe "%ProgramFiles%\Win...ery\PhotoViewer.dll", var var
+  // rundll32.exe "%ProgramFiles%\Windows Photo Gallery\PhotoViewer.dll"
+  // C:\Windows\System32\rundll32.exe "path to dll", var var
+  // %SystemRoot%\System32\rundll32.exe "%ProgramFiles%\Win...ery\Photo
+  //    Viewer.dll", var var
+
+  // Expand environment variables so we have full path strings.
+  uint32_t bufLength = ::ExpandEnvironmentStringsW(handlerCommand.get(),
+                                                   L"", 0);
+  if (bufLength == 0) // Error
+    return false;
+
+  auto destination = mozilla::MakeUniqueFallible<wchar_t[]>(bufLength);
+  if (!destination)
+    return false;
+  if (!::ExpandEnvironmentStringsW(handlerCommand.get(), destination.get(),
+                                   bufLength))
+    return false;
+
+  handlerCommand.Assign(destination.get());
+
+  // Remove quotes around paths
+  handlerCommand.StripChars("\"");
+
+  // Strip windows host process bootstrap so we can get to the actual
+  // handler.
+  StripRundll32(handlerCommand);
+
+  // Trim any command parameters so that we have a native path we can
+  // initialize a local file with.
+  CleanupHandlerPath(handlerCommand);
+
+  aCommandHandler.Assign(handlerCommand);
+  return true;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::InitWithCommandLine(const nsAString& aCommandLine)
+{
+  nsAutoString commandLine(aCommandLine);
+  if (!CleanupCmdHandlerPath(commandLine)) {
+    return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+  }
+  return InitWithPath(commandLine);
+}
+
+NS_IMETHODIMP
+nsLocalFile::OpenNSPRFileDesc(int32_t aFlags, int32_t aMode,
+                              PRFileDesc** aResult)
+{
+  nsresult rv = OpenNSPRFileDescMaybeShareDelete(aFlags, aMode, false, aResult);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::OpenANSIFileDesc(const char* aMode, FILE** aResult)
+{
+  nsresult rv = ResolveAndStat();
+  if (NS_FAILED(rv) && rv != NS_ERROR_FILE_NOT_FOUND) {
+    return rv;
+  }
+
+  *aResult = _wfopen(mResolvedPath.get(), NS_ConvertASCIItoUTF16(aMode).get());
+  if (*aResult) {
+    return NS_OK;
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+
+
+NS_IMETHODIMP
+nsLocalFile::Create(uint32_t aType, uint32_t aAttributes)
+{
+  if (aType != NORMAL_FILE_TYPE && aType != DIRECTORY_TYPE) {
+    return NS_ERROR_FILE_UNKNOWN_TYPE;
+  }
+
+  nsresult rv = ResolveAndStat();
+  if (NS_FAILED(rv) && rv != NS_ERROR_FILE_NOT_FOUND) {
+    return rv;
+  }
+
+  // create directories to target
+  //
+  // A given local file can be either one of these forms:
+  //
+  //   - normal:    X:\some\path\on\this\drive
+  //                       ^--- start here
+  //
+  //   - UNC path:  \\machine\volume\some\path\on\this\drive
+  //                                     ^--- start here
+  //
+  // Skip the first 'X:\' for the first form, and skip the first full
+  // '\\machine\volume\' segment for the second form.
+
+  wchar_t* path = wwc(mResolvedPath.BeginWriting());
+
+  if (path[0] == L'\\' && path[1] == L'\\') {
+    // dealing with a UNC path here; skip past '\\machine\'
+    path = wcschr(path + 2, L'\\');
+    if (!path) {
+      return NS_ERROR_FILE_INVALID_PATH;
+    }
+    ++path;
+  }
+
+  // search for first slash after the drive (or volume) name
+  wchar_t* slash = wcschr(path, L'\\');
+
+  nsresult directoryCreateError = NS_OK;
+  if (slash) {
+    // skip the first '\\'
+    ++slash;
+    slash = wcschr(slash, L'\\');
+
+    while (slash) {
+      *slash = L'\0';
+
+      if (!::CreateDirectoryW(mResolvedPath.get(), nullptr)) {
+        rv = ConvertWinError(GetLastError());
+        if (NS_ERROR_FILE_NOT_FOUND == rv &&
+            NS_ERROR_FILE_ACCESS_DENIED == directoryCreateError) {
+          // If a previous CreateDirectory failed due to access, return that.
+          return NS_ERROR_FILE_ACCESS_DENIED;
+        }
+        // perhaps the base path already exists, or perhaps we don't have
+        // permissions to create the directory.  NOTE: access denied could
+        // occur on a parent directory even though it exists.
+        else if (rv != NS_ERROR_FILE_ALREADY_EXISTS &&
+                 rv != NS_ERROR_FILE_ACCESS_DENIED) {
+          return rv;
+        }
+
+        directoryCreateError = rv;
+      }
+      *slash = L'\\';
+      ++slash;
+      slash = wcschr(slash, L'\\');
+    }
+  }
+
+  if (aType == NORMAL_FILE_TYPE) {
+    PRFileDesc* file;
+    rv = OpenFile(mResolvedPath,
+                  PR_RDONLY | PR_CREATE_FILE | PR_APPEND | PR_EXCL,
+                  aAttributes, false, &file);
+    if (file) {
+      PR_Close(file);
+    }
+
+    if (rv == NS_ERROR_FILE_ACCESS_DENIED) {
+      // need to return already-exists for directories (bug 452217)
+      bool isdir;
+      if (NS_SUCCEEDED(IsDirectory(&isdir)) && isdir) {
+        rv = NS_ERROR_FILE_ALREADY_EXISTS;
+      }
+    } else if (NS_ERROR_FILE_NOT_FOUND == rv &&
+               NS_ERROR_FILE_ACCESS_DENIED == directoryCreateError) {
+      // If a previous CreateDirectory failed due to access, return that.
+      return NS_ERROR_FILE_ACCESS_DENIED;
+    }
+    return rv;
+  }
+
+  if (aType == DIRECTORY_TYPE) {
+    if (!::CreateDirectoryW(mResolvedPath.get(), nullptr)) {
+      rv = ConvertWinError(GetLastError());
+      if (NS_ERROR_FILE_NOT_FOUND == rv &&
+          NS_ERROR_FILE_ACCESS_DENIED == directoryCreateError) {
+        // If a previous CreateDirectory failed due to access, return that.
+        return NS_ERROR_FILE_ACCESS_DENIED;
+      }
+      return rv;
+    }
+    return NS_OK;
+  }
+
+  return NS_ERROR_FILE_UNKNOWN_TYPE;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::Append(const nsAString& aNode)
+{
+  // append this path, multiple components are not permitted
+  return AppendInternal(PromiseFlatString(aNode), false);
+}
+
+NS_IMETHODIMP
+nsLocalFile::AppendRelativePath(const nsAString& aNode)
+{
+  // append this path, multiple components are permitted
+  return AppendInternal(PromiseFlatString(aNode), true);
+}
+
+
+nsresult
+nsLocalFile::AppendInternal(const nsAFlatString& aNode,
+                            bool aMultipleComponents)
+{
+  if (aNode.IsEmpty()) {
+    return NS_OK;
+  }
+
+  // check the relative path for validity
+  if (aNode.First() == L'\\' ||               // can't start with an '\'
+      aNode.Contains(L'/') ||                 // can't contain /
+      aNode.EqualsASCII("..")) {              // can't be ..
+    return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+  }
+
+  if (aMultipleComponents) {
+    // can't contain .. as a path component. Ensure that the valid components
+    // "foo..foo", "..foo", and "foo.." are not falsely detected,
+    // but the invalid paths "..\", "foo\..", "foo\..\foo",
+    // "..\foo", etc are.
+    NS_NAMED_LITERAL_STRING(doubleDot, "\\..");
+    nsAString::const_iterator start, end, offset;
+    aNode.BeginReading(start);
+    aNode.EndReading(end);
+    offset = end;
+    while (FindInReadable(doubleDot, start, offset)) {
+      if (offset == end || *offset == L'\\') {
+        return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+      }
+      start = offset;
+      offset = end;
+    }
+
+    // catches the remaining cases of prefixes
+    if (StringBeginsWith(aNode, NS_LITERAL_STRING("..\\"))) {
+      return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+    }
+  }
+  // single components can't contain '\'
+  else if (aNode.Contains(L'\\')) {
+    return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+  }
+
+  MakeDirty();
+
+  mWorkingPath.Append('\\');
+  mWorkingPath.Append(aNode);
+
+  return NS_OK;
+}
+
+nsresult
+nsLocalFile::OpenNSPRFileDescMaybeShareDelete(int32_t aFlags,
+                                              int32_t aMode,
+                                              bool aShareDelete,
+                                              PRFileDesc** aResult)
+{
+  nsresult rv = Resolve();
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  return OpenFile(mResolvedPath, aFlags, aMode, aShareDelete, aResult);
+}
+
+#define TOUPPER(u) (((u) >= L'a' && (u) <= L'z') ? \
+                    (u) - (L'a' - L'A') : (u))
+
+NS_IMETHODIMP
+nsLocalFile::Normalize()
+{
+  // XXX See bug 187957 comment 18 for possible problems with this implementation.
+
+  if (mWorkingPath.IsEmpty()) {
+    return NS_OK;
+  }
+
+  nsAutoString path(mWorkingPath);
+
+  // find the index of the root backslash for the path. Everything before
+  // this is considered fully normalized and cannot be ascended beyond
+  // using ".."  For a local drive this is the first slash (e.g. "c:\").
+  // For a UNC path it is the slash following the share name
+  // (e.g. "\\server\share\").
+  int32_t rootIdx = 2;        // default to local drive
+  if (path.First() == L'\\') {  // if a share then calculate the rootIdx
+    rootIdx = path.FindChar(L'\\', 2);   // skip \\ in front of the server
+    if (rootIdx == kNotFound) {
+      return NS_OK;  // already normalized
+    }
+    rootIdx = path.FindChar(L'\\', rootIdx + 1);
+    if (rootIdx == kNotFound) {
+      return NS_OK;  // already normalized
+    }
+  } else if (path.CharAt(rootIdx) != L'\\') {
+    // The path has been specified relative to the current working directory
+    // for that drive. To normalize it, the current working directory for
+    // that drive needs to be inserted before the supplied relative path
+    // which will provide an absolute path (and the rootIdx will still be 2).
+    WCHAR cwd[MAX_PATH];
+    WCHAR* pcwd = cwd;
+    int drive = TOUPPER(path.First()) - 'A' + 1;
+    /* We need to worry about IPH, for details read bug 419326.
+     * _getdrives - http://msdn2.microsoft.com/en-us/library/xdhk0xd2.aspx
+     * uses a bitmask, bit 0 is 'a:'
+     * _chdrive - http://msdn2.microsoft.com/en-us/library/0d1409hb.aspx
+     * _getdcwd - http://msdn2.microsoft.com/en-us/library/7t2zk3s4.aspx
+     * take an int, 1 is 'a:'.
+     *
+     * Because of this, we need to do some math. Subtract 1 to convert from
+     * _chdrive/_getdcwd format to _getdrives drive numbering.
+     * Shift left x bits to convert from integer indexing to bitfield indexing.
+     * And of course, we need to find out if the drive is in the bitmask.
+     *
+     * If we're really unlucky, we can still lose, but only if the user
+     * manages to eject the drive between our call to _getdrives() and
+     * our *calls* to _wgetdcwd.
+     */
+    if (!((1 << (drive - 1)) & _getdrives())) {
+      return NS_ERROR_FILE_INVALID_PATH;
+    }
+    if (!_wgetdcwd(drive, pcwd, MAX_PATH)) {
+      pcwd = _wgetdcwd(drive, 0, 0);
+    }
+    if (!pcwd) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    nsAutoString currentDir(pcwd);
+    if (pcwd != cwd) {
+      free(pcwd);
+    }
+
+    if (currentDir.Last() == '\\') {
+      path.Replace(0, 2, currentDir);
+    } else {
+      path.Replace(0, 2, currentDir + NS_LITERAL_STRING("\\"));
+    }
+  }
+  NS_POSTCONDITION(0 < rootIdx && rootIdx < (int32_t)path.Length(), "rootIdx is invalid");
+  NS_POSTCONDITION(path.CharAt(rootIdx) == '\\', "rootIdx is invalid");
+
+  // if there is nothing following the root path then it is already normalized
+  if (rootIdx + 1 == (int32_t)path.Length()) {
+    return NS_OK;
+  }
+
+  // assign the root
+  const char16_t* pathBuffer = path.get();  // simplify access to the buffer
+  mWorkingPath.SetCapacity(path.Length());  // it won't ever grow longer
+  mWorkingPath.Assign(pathBuffer, rootIdx);
+
+  // Normalize the path components. The actions taken are:
+  //
+  //  "\\"    condense to single backslash
+  //  "."     remove from path
+  //  ".."    up a directory
+  //  "..."   remove from path (any number of dots > 2)
+  //
+  // The last form is something that Windows 95 and 98 supported and
+  // is a shortcut for changing up multiple directories. Windows XP
+  // and ilk ignore it in a path, as is done here.
+  int32_t len, begin, end = rootIdx;
+  while (end < (int32_t)path.Length()) {
+    // find the current segment (text between the backslashes) to
+    // be examined, this will set the following variables:
+    //  begin == index of first char in segment
+    //  end   == index 1 char after last char in segment
+    //  len   == length of segment
+    begin = end + 1;
+    end = path.FindChar('\\', begin);
+    if (end == kNotFound) {
+      end = path.Length();
+    }
+    len = end - begin;
+
+    // ignore double backslashes
+    if (len == 0) {
+      continue;
+    }
+
+    // len != 0, and interesting paths always begin with a dot
+    if (pathBuffer[begin] == '.') {
+      // ignore single dots
+      if (len == 1) {
+        continue;
+      }
+
+      // handle multiple dots
+      if (len >= 2 && pathBuffer[begin + 1] == L'.') {
+        // back up a path component on double dot
+        if (len == 2) {
+          int32_t prev = mWorkingPath.RFindChar('\\');
+          if (prev >= rootIdx) {
+            mWorkingPath.Truncate(prev);
+          }
+          continue;
+        }
+
+        // length is > 2 and the first two characters are dots.
+        // if the rest of the string is dots, then ignore it.
+        int idx = len - 1;
+        for (; idx >= 2; --idx) {
+          if (pathBuffer[begin + idx] != L'.') {
+            break;
+          }
+        }
+
+        // this is true if the loop above didn't break
+        // and all characters in this segment are dots.
+        if (idx < 2) {
+          continue;
+        }
+      }
+    }
+
+    // add the current component to the path, including the preceding backslash
+    mWorkingPath.Append(pathBuffer + begin - 1, len + 1);
+  }
+
+  // kill trailing dots and spaces.
+  int32_t filePathLen = mWorkingPath.Length() - 1;
+  while (filePathLen > 0 && (mWorkingPath[filePathLen] == L' ' ||
+                             mWorkingPath[filePathLen] == L'.')) {
+    mWorkingPath.Truncate(filePathLen--);
+  }
+
+  MakeDirty();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetLeafName(nsAString& aLeafName)
+{
+  aLeafName.Truncate();
+
+  if (mWorkingPath.IsEmpty()) {
+    return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+  }
+
+  int32_t offset = mWorkingPath.RFindChar(L'\\');
+
+  // if the working path is just a node without any lashes.
+  if (offset == kNotFound) {
+    aLeafName = mWorkingPath;
+  } else {
+    aLeafName = Substring(mWorkingPath, offset + 1);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetLeafName(const nsAString& aLeafName)
+{
+  MakeDirty();
+
+  if (mWorkingPath.IsEmpty()) {
+    return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+  }
+
+  // cannot use nsCString::RFindChar() due to 0x5c problem
+  int32_t offset = mWorkingPath.RFindChar(L'\\');
+  if (offset) {
+    mWorkingPath.Truncate(offset + 1);
+  }
+  mWorkingPath.Append(aLeafName);
+
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::GetPath(nsAString& aResult)
+{
+  aResult = mWorkingPath;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetCanonicalPath(nsAString& aResult)
+{
+  EnsureShortPath();
+  aResult.Assign(mShortWorkingPath);
+  return NS_OK;
+}
+
+typedef struct
+{
+  WORD wLanguage;
+  WORD wCodePage;
+} LANGANDCODEPAGE;
+
+NS_IMETHODIMP
+nsLocalFile::GetVersionInfoField(const char* aField, nsAString& aResult)
+{
+  nsresult rv = ResolveAndStat();
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  rv = NS_ERROR_FAILURE;
+
+  const WCHAR* path =
+    mFollowSymlinks ? mResolvedPath.get() : mWorkingPath.get();
+
+  DWORD dummy;
+  DWORD size = ::GetFileVersionInfoSizeW(path, &dummy);
+  if (!size) {
+    return rv;
+  }
+
+  void* ver = moz_xcalloc(size, 1);
+  if (::GetFileVersionInfoW(path, 0, size, ver)) {
+    LANGANDCODEPAGE* translate = nullptr;
+    UINT pageCount;
+    BOOL queryResult = ::VerQueryValueW(ver, L"\\VarFileInfo\\Translation",
+                                        (void**)&translate, &pageCount);
+    if (queryResult && translate) {
+      for (int32_t i = 0; i < 2; ++i) {
+        wchar_t subBlock[MAX_PATH];
+        _snwprintf(subBlock, MAX_PATH,
+                   L"\\StringFileInfo\\%04x%04x\\%s",
+                   (i == 0 ? translate[0].wLanguage : ::GetUserDefaultLangID()),
+                   translate[0].wCodePage,
+                   NS_ConvertASCIItoUTF16(
+                     nsDependentCString(aField)).get());
+        subBlock[MAX_PATH - 1] = 0;
+        LPVOID value = nullptr;
+        UINT size;
+        queryResult = ::VerQueryValueW(ver, subBlock, &value, &size);
+        if (queryResult && value) {
+          aResult.Assign(static_cast<char16_t*>(value));
+          if (!aResult.IsEmpty()) {
+            rv = NS_OK;
+            break;
+          }
+        }
+      }
+    }
+  }
+  free(ver);
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetShortcut(nsIFile* aTargetFile,
+                         nsIFile* aWorkingDir,
+                         const char16_t* aArgs,
+                         const char16_t* aDescription,
+                         nsIFile* aIconFile,
+                         int32_t aIconIndex)
+{
+  bool exists;
+  nsresult rv = this->Exists(&exists);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  const WCHAR* targetFilePath = nullptr;
+  const WCHAR* workingDirPath = nullptr;
+  const WCHAR* iconFilePath = nullptr;
+
+  nsAutoString targetFilePathAuto;
+  if (aTargetFile) {
+    rv = aTargetFile->GetPath(targetFilePathAuto);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+    targetFilePath = targetFilePathAuto.get();
+  }
+
+  nsAutoString workingDirPathAuto;
+  if (aWorkingDir) {
+    rv = aWorkingDir->GetPath(workingDirPathAuto);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+    workingDirPath = workingDirPathAuto.get();
+  }
+
+  nsAutoString iconPathAuto;
+  if (aIconFile) {
+    rv = aIconFile->GetPath(iconPathAuto);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+    iconFilePath = iconPathAuto.get();
+  }
+
+  rv = gResolver->SetShortcut(exists,
+                              mWorkingPath.get(),
+                              targetFilePath,
+                              workingDirPath,
+                              char16ptr_t(aArgs),
+                              char16ptr_t(aDescription),
+                              iconFilePath,
+                              iconFilePath ? aIconIndex : 0);
+  if (targetFilePath && NS_SUCCEEDED(rv)) {
+    MakeDirty();
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::OpenNSPRFileDescShareDelete(int32_t aFlags,
+                                         int32_t aMode,
+                                         PRFileDesc** aResult)
+{
+  nsresult rv = OpenNSPRFileDescMaybeShareDelete(aFlags, aMode, true, aResult);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  return NS_OK;
+}
+
+/**
+ * Determines if the drive type for the specified file is rmeote or local.
+ *
+ * @param path   The path of the file to check
+ * @param remote Out parameter, on function success holds true if the specified
+ *               file path is remote, or false if the file path is local.
+ * @return true  on success. The return value implies absolutely nothing about
+ *               wether the file is local or remote.
+*/
+static bool
+IsRemoteFilePath(LPCWSTR aPath, bool& aRemote)
+{
+  // Obtain the parent directory path and make sure it ends with
+  // a trailing backslash.
+  WCHAR dirPath[MAX_PATH + 1] = { 0 };
+  wcsncpy(dirPath, aPath, MAX_PATH);
+  if (!PathRemoveFileSpecW(dirPath)) {
+    return false;
+  }
+  size_t len = wcslen(dirPath);
+  // In case the dirPath holds exaclty MAX_PATH and remains unchanged, we
+  // recheck the required length here since we need to terminate it with
+  // a backslash.
+  if (len >= MAX_PATH) {
+    return false;
+  }
+
+  dirPath[len] = L'\\';
+  dirPath[len + 1] = L'\0';
+  UINT driveType = GetDriveTypeW(dirPath);
+  aRemote = driveType == DRIVE_REMOTE;
+  return true;
+}
+
+nsresult
+nsLocalFile::CopySingleFile(nsIFile* aSourceFile, nsIFile* aDestParent,
+                            const nsAString& aNewName, uint32_t aOptions)
+{
+  nsresult rv = NS_OK;
+  nsAutoString filePath;
+
+  bool move = aOptions & (Move | Rename);
+
+  // get the path that we are going to copy to.
+  // Since windows does not know how to auto
+  // resolve shortcuts, we must work with the
+  // target.
+  nsAutoString destPath;
+  aDestParent->GetTarget(destPath);
+
+  destPath.Append('\\');
+
+  if (aNewName.IsEmpty()) {
+    nsAutoString aFileName;
+    aSourceFile->GetLeafName(aFileName);
+    destPath.Append(aFileName);
+  } else {
+    destPath.Append(aNewName);
+  }
+
+
+  if (aOptions & FollowSymlinks) {
+    rv = aSourceFile->GetTarget(filePath);
+    if (filePath.IsEmpty()) {
+      rv = aSourceFile->GetPath(filePath);
+    }
+  } else {
+    rv = aSourceFile->GetPath(filePath);
+  }
+
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // Pass the flag COPY_FILE_NO_BUFFERING to CopyFileEx as we may be copying
+  // to a SMBV2 remote drive. Without this parameter subsequent append mode
+  // file writes can cause the resultant file to become corrupt. We only need to do
+  // this if the major version of Windows is > 5(Only Windows Vista and above
+  // can support SMBV2).  With a 7200RPM hard drive:
+  // Copying a 1KB file with COPY_FILE_NO_BUFFERING takes about 30-60ms.
+  // Copying a 1KB file without COPY_FILE_NO_BUFFERING takes < 1ms.
+  // So we only use COPY_FILE_NO_BUFFERING when we have a remote drive.
+  int copyOK;
+  DWORD dwCopyFlags = COPY_FILE_ALLOW_DECRYPTED_DESTINATION;
+  if (IsVistaOrLater()) {
+    bool path1Remote, path2Remote;
+    if (!IsRemoteFilePath(filePath.get(), path1Remote) ||
+        !IsRemoteFilePath(destPath.get(), path2Remote) ||
+        path1Remote || path2Remote) {
+      dwCopyFlags |= COPY_FILE_NO_BUFFERING;
+    }
+  }
+
+  if (!move) {
+    copyOK = ::CopyFileExW(filePath.get(), destPath.get(), nullptr,
+                           nullptr, nullptr, dwCopyFlags);
+  } else {
+    copyOK = ::MoveFileExW(filePath.get(), destPath.get(),
+                           MOVEFILE_REPLACE_EXISTING);
+
+    // Check if copying the source file to a different volume,
+    // as this could be an SMBV2 mapped drive.
+    if (!copyOK && GetLastError() == ERROR_NOT_SAME_DEVICE) {
+      if (aOptions & Rename) {
+        return NS_ERROR_FILE_ACCESS_DENIED;
+      }
+      copyOK = CopyFileExW(filePath.get(), destPath.get(), nullptr,
+                           nullptr, nullptr, dwCopyFlags);
+
+      if (copyOK) {
+        DeleteFileW(filePath.get());
+      }
+    }
+  }
+
+  if (!copyOK) { // CopyFileEx and MoveFileEx return zero at failure.
+    rv = ConvertWinError(GetLastError());
+  } else if (move && !(aOptions & SkipNtfsAclReset)) {
+    // Set security permissions to inherit from parent.
+    // Note: propagates to all children: slow for big file trees
+    PACL pOldDACL = nullptr;
+    PSECURITY_DESCRIPTOR pSD = nullptr;
+    ::GetNamedSecurityInfoW((LPWSTR)destPath.get(), SE_FILE_OBJECT,
+                            DACL_SECURITY_INFORMATION,
+                            nullptr, nullptr, &pOldDACL, nullptr, &pSD);
+    if (pOldDACL)
+      ::SetNamedSecurityInfoW((LPWSTR)destPath.get(), SE_FILE_OBJECT,
+                              DACL_SECURITY_INFORMATION |
+                              UNPROTECTED_DACL_SECURITY_INFORMATION,
+                              nullptr, nullptr, pOldDACL, nullptr);
+    if (pSD) {
+      LocalFree((HLOCAL)pSD);
+    }
+  }
+
+  return rv;
+}
+
+nsresult
+nsLocalFile::CopyMove(nsIFile* aParentDir, const nsAString& aNewName,
+                      uint32_t aOptions)
+{
+  bool move = aOptions & (Move | Rename);
+  bool followSymlinks = aOptions & FollowSymlinks;
+
+  nsCOMPtr<nsIFile> newParentDir = aParentDir;
+  // check to see if this exists, otherwise return an error.
+  // we will check this by resolving.  If the user wants us
+  // to follow links, then we are talking about the target,
+  // hence we can use the |FollowSymlinks| option.
+  nsresult rv  = ResolveAndStat();
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (!newParentDir) {
+    // no parent was specified.  We must rename.
+    if (aNewName.IsEmpty()) {
+      return NS_ERROR_INVALID_ARG;
+    }
+
+    rv = GetParent(getter_AddRefs(newParentDir));
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+  }
+
+  if (!newParentDir) {
+    return NS_ERROR_FILE_DESTINATION_NOT_DIR;
+  }
+
+  // make sure it exists and is a directory.  Create it if not there.
+  bool exists;
+  newParentDir->Exists(&exists);
+  if (!exists) {
+    rv = newParentDir->Create(DIRECTORY_TYPE, 0644);  // TODO, what permissions should we use
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+  } else {
+    bool isDir;
+    newParentDir->IsDirectory(&isDir);
+    if (!isDir) {
+      if (followSymlinks) {
+        bool isLink;
+        newParentDir->IsSymlink(&isLink);
+        if (isLink) {
+          nsAutoString target;
+          newParentDir->GetTarget(target);
+
+          nsCOMPtr<nsIFile> realDest = new nsLocalFile();
+          rv = realDest->InitWithPath(target);
+
+          if (NS_FAILED(rv)) {
+            return rv;
+          }
+
+          return CopyMove(realDest, aNewName, aOptions);
+        }
+      } else {
+        return NS_ERROR_FILE_DESTINATION_NOT_DIR;
+      }
+    }
+  }
+
+  // Try different ways to move/copy files/directories
+  bool done = false;
+  bool isDir;
+  IsDirectory(&isDir);
+  bool isSymlink;
+  IsSymlink(&isSymlink);
+
+  // Try to move the file or directory, or try to copy a single file (or non-followed symlink)
+  if (move || !isDir || (isSymlink && !followSymlinks)) {
+    // Copy/Move single file, or move a directory
+    if (!aParentDir) {
+      aOptions |= SkipNtfsAclReset;
+    }
+    rv = CopySingleFile(this, newParentDir, aNewName, aOptions);
+    done = NS_SUCCEEDED(rv);
+    // If we are moving a directory and that fails, fallback on directory
+    // enumeration.  See bug 231300 for details.
+    if (!done && !(move && isDir)) {
+      return rv;
+    }
+  }
+
+  // Not able to copy or move directly, so enumerate it
+  if (!done) {
+    // create a new target destination in the new parentDir;
+    nsCOMPtr<nsIFile> target;
+    rv = newParentDir->Clone(getter_AddRefs(target));
+
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    nsAutoString allocatedNewName;
+    if (aNewName.IsEmpty()) {
+      bool isLink;
+      IsSymlink(&isLink);
+      if (isLink) {
+        nsAutoString temp;
+        GetTarget(temp);
+        int32_t offset = temp.RFindChar(L'\\');
+        if (offset == kNotFound) {
+          allocatedNewName = temp;
+        } else {
+          allocatedNewName = Substring(temp, offset + 1);
+        }
+      } else {
+        GetLeafName(allocatedNewName);// this should be the leaf name of the
+      }
+    } else {
+      allocatedNewName = aNewName;
+    }
+
+    rv = target->Append(allocatedNewName);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    allocatedNewName.Truncate();
+
+    // check if the destination directory already exists
+    target->Exists(&exists);
+    if (!exists) {
+      // if the destination directory cannot be created, return an error
+      rv = target->Create(DIRECTORY_TYPE, 0644);  // TODO, what permissions should we use
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+    } else {
+      // check if the destination directory is writable and empty
+      bool isWritable;
+
+      target->IsWritable(&isWritable);
+      if (!isWritable) {
+        return NS_ERROR_FILE_ACCESS_DENIED;
+      }
+
+      nsCOMPtr<nsISimpleEnumerator> targetIterator;
+      rv = target->GetDirectoryEntries(getter_AddRefs(targetIterator));
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+
+      bool more;
+      targetIterator->HasMoreElements(&more);
+      // return error if target directory is not empty
+      if (more) {
+        return NS_ERROR_FILE_DIR_NOT_EMPTY;
+      }
+    }
+
+    RefPtr<nsDirEnumerator> dirEnum = new nsDirEnumerator();
+
+    rv = dirEnum->Init(this);
+    if (NS_FAILED(rv)) {
+      NS_WARNING("dirEnum initialization failed");
+      return rv;
+    }
+
+    bool more = false;
+    while (NS_SUCCEEDED(dirEnum->HasMoreElements(&more)) && more) {
+      nsCOMPtr<nsISupports> item;
+      nsCOMPtr<nsIFile> file;
+      dirEnum->GetNext(getter_AddRefs(item));
+      file = do_QueryInterface(item);
+      if (file) {
+        bool isDir, isLink;
+
+        file->IsDirectory(&isDir);
+        file->IsSymlink(&isLink);
+
+        if (move) {
+          if (followSymlinks) {
+            return NS_ERROR_FAILURE;
+          }
+
+          rv = file->MoveTo(target, EmptyString());
+          if (NS_FAILED(rv)) {
+            return rv;
+          }
+        } else {
+          if (followSymlinks) {
+            rv = file->CopyToFollowingLinks(target, EmptyString());
+          } else {
+            rv = file->CopyTo(target, EmptyString());
+          }
+          if (NS_FAILED(rv)) {
+            return rv;
+          }
+        }
+      }
+    }
+    // we've finished moving all the children of this directory
+    // in the new directory.  so now delete the directory
+    // note, we don't need to do a recursive delete.
+    // MoveTo() is recursive.  At this point,
+    // we've already moved the children of the current folder
+    // to the new location.  nothing should be left in the folder.
+    if (move) {
+      rv = Remove(false /* recursive */);
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+    }
+  }
+
+
+  // If we moved, we want to adjust this.
+  if (move) {
+    MakeDirty();
+
+    nsAutoString newParentPath;
+    newParentDir->GetPath(newParentPath);
+
+    if (newParentPath.IsEmpty()) {
+      return NS_ERROR_FAILURE;
+    }
+
+    if (aNewName.IsEmpty()) {
+      nsAutoString aFileName;
+      GetLeafName(aFileName);
+
+      InitWithPath(newParentPath);
+      Append(aFileName);
+    } else {
+      InitWithPath(newParentPath);
+      Append(aNewName);
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::CopyTo(nsIFile* aNewParentDir, const nsAString& aNewName)
+{
+  return CopyMove(aNewParentDir, aNewName, 0);
+}
+
+NS_IMETHODIMP
+nsLocalFile::CopyToFollowingLinks(nsIFile* aNewParentDir,
+                                  const nsAString& aNewName)
+{
+  return CopyMove(aNewParentDir, aNewName, FollowSymlinks);
+}
+
+NS_IMETHODIMP
+nsLocalFile::MoveTo(nsIFile* aNewParentDir, const nsAString& aNewName)
+{
+  return CopyMove(aNewParentDir, aNewName, Move);
+}
+
+NS_IMETHODIMP
+nsLocalFile::RenameTo(nsIFile* aNewParentDir, const nsAString& aNewName)
+{
+  nsCOMPtr<nsIFile> targetParentDir = aNewParentDir;
+  // check to see if this exists, otherwise return an error.
+  // we will check this by resolving.  If the user wants us
+  // to follow links, then we are talking about the target,
+  // hence we can use the |followSymlinks| parameter.
+  nsresult rv = ResolveAndStat();
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (!targetParentDir) {
+    // no parent was specified.  We must rename.
+    if (aNewName.IsEmpty()) {
+      return NS_ERROR_INVALID_ARG;
+    }
+    rv = GetParent(getter_AddRefs(targetParentDir));
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+  }
+
+  if (!targetParentDir) {
+    return NS_ERROR_FILE_DESTINATION_NOT_DIR;
+  }
+
+  // make sure it exists and is a directory.  Create it if not there.
+  bool exists;
+  targetParentDir->Exists(&exists);
+  if (!exists) {
+    rv = targetParentDir->Create(DIRECTORY_TYPE, 0644);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+  } else {
+    bool isDir;
+    targetParentDir->IsDirectory(&isDir);
+    if (!isDir) {
+      return NS_ERROR_FILE_DESTINATION_NOT_DIR;
+    }
+  }
+
+  uint32_t options = Rename;
+  if (!aNewParentDir) {
+    options |= SkipNtfsAclReset;
+  }
+  // Move single file, or move a directory
+  return CopySingleFile(this, targetParentDir, aNewName, options);
+}
+
+NS_IMETHODIMP
+nsLocalFile::RenameToNative(nsIFile* aNewParentDir, const nsACString& aNewName)
+{
+  nsAutoString tmp;
+  nsresult rv = NS_CopyNativeToUnicode(aNewName, tmp);
+  if (NS_SUCCEEDED(rv)) {
+    return RenameTo(aNewParentDir, tmp);
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::Load(PRLibrary** aResult)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  bool isFile;
+  nsresult rv = IsFile(&isFile);
+
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (!isFile) {
+    return NS_ERROR_FILE_IS_DIRECTORY;
+  }
+
+#ifdef NS_BUILD_REFCNT_LOGGING
+  nsTraceRefcnt::SetActivityIsLegal(false);
+#endif
+
+  PRLibSpec libSpec;
+  libSpec.value.pathname_u = mResolvedPath.get();
+  libSpec.type = PR_LibSpec_PathnameU;
+  *aResult =  PR_LoadLibraryWithFlags(libSpec, 0);
+
+#ifdef NS_BUILD_REFCNT_LOGGING
+  nsTraceRefcnt::SetActivityIsLegal(true);
+#endif
+
+  if (*aResult) {
+    return NS_OK;
+  }
+  return NS_ERROR_NULL_POINTER;
+}
+
+NS_IMETHODIMP
+nsLocalFile::Remove(bool aRecursive)
+{
+  // NOTE:
+  //
+  // if the working path points to a shortcut, then we will only
+  // delete the shortcut itself.  even if the shortcut points to
+  // a directory, we will not recurse into that directory or
+  // delete that directory itself.  likewise, if the shortcut
+  // points to a normal file, we will not delete the real file.
+  // this is done to be consistent with the other platforms that
+  // behave this way.  we do this even if the followLinks attribute
+  // is set to true.  this helps protect against misuse that could
+  // lead to security bugs (e.g., bug 210588).
+  //
+  // Since shortcut files are no longer permitted to be used as unix-like
+  // symlinks interspersed in the path (e.g. "c:/file.lnk/foo/bar.txt")
+  // this processing is a lot simpler. Even if the shortcut file is
+  // pointing to a directory, only the mWorkingPath value is used and so
+  // only the shortcut file will be deleted.
+
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  bool isDir, isLink;
+  nsresult rv;
+
+  isDir = false;
+  rv = IsSymlink(&isLink);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // only check to see if we have a directory if it isn't a link
+  if (!isLink) {
+    rv = IsDirectory(&isDir);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+  }
+
+  if (isDir) {
+    if (aRecursive) {
+      RefPtr<nsDirEnumerator> dirEnum = new nsDirEnumerator();
+
+      rv = dirEnum->Init(this);
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+
+      bool more = false;
+      while (NS_SUCCEEDED(dirEnum->HasMoreElements(&more)) && more) {
+        nsCOMPtr<nsISupports> item;
+        dirEnum->GetNext(getter_AddRefs(item));
+        nsCOMPtr<nsIFile> file = do_QueryInterface(item);
+        if (file) {
+          file->Remove(aRecursive);
+        }
+      }
+    }
+    if (RemoveDirectoryW(mWorkingPath.get()) == 0) {
+      return ConvertWinError(GetLastError());
+    }
+  } else {
+    if (DeleteFileW(mWorkingPath.get()) == 0) {
+      return ConvertWinError(GetLastError());
+    }
+  }
+
+  MakeDirty();
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetLastModifiedTime(PRTime* aLastModifiedTime)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  if (NS_WARN_IF(!aLastModifiedTime)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // get the modified time of the target as determined by mFollowSymlinks
+  // If true, then this will be for the target of the shortcut file,
+  // otherwise it will be for the shortcut file itself (i.e. the same
+  // results as GetLastModifiedTimeOfLink)
+
+  nsresult rv = ResolveAndStat();
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // microseconds -> milliseconds
+  *aLastModifiedTime = mFileInfo64.modifyTime / PR_USEC_PER_MSEC;
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::GetLastModifiedTimeOfLink(PRTime* aLastModifiedTime)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  if (NS_WARN_IF(!aLastModifiedTime)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // The caller is assumed to have already called IsSymlink
+  // and to have found that this file is a link.
+
+  PRFileInfo64 info;
+  nsresult rv = GetFileInfo(mWorkingPath, &info);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // microseconds -> milliseconds
+  *aLastModifiedTime = info.modifyTime / PR_USEC_PER_MSEC;
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::SetLastModifiedTime(PRTime aLastModifiedTime)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  nsresult rv = ResolveAndStat();
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // set the modified time of the target as determined by mFollowSymlinks
+  // If true, then this will be for the target of the shortcut file,
+  // otherwise it will be for the shortcut file itself (i.e. the same
+  // results as SetLastModifiedTimeOfLink)
+
+  rv = SetModDate(aLastModifiedTime, mResolvedPath.get());
+  if (NS_SUCCEEDED(rv)) {
+    MakeDirty();
+  }
+
+  return rv;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::SetLastModifiedTimeOfLink(PRTime aLastModifiedTime)
+{
+  // The caller is assumed to have already called IsSymlink
+  // and to have found that this file is a link.
+
+  nsresult rv = SetModDate(aLastModifiedTime, mWorkingPath.get());
+  if (NS_SUCCEEDED(rv)) {
+    MakeDirty();
+  }
+
+  return rv;
+}
+
+nsresult
+nsLocalFile::SetModDate(PRTime aLastModifiedTime, const wchar_t* aFilePath)
+{
+  // The FILE_FLAG_BACKUP_SEMANTICS is required in order to change the
+  // modification time for directories.
+  HANDLE file = ::CreateFileW(aFilePath,         // pointer to name of the file
+                              GENERIC_WRITE,     // access (write) mode
+                              0,                 // share mode
+                              nullptr,           // pointer to security attributes
+                              OPEN_EXISTING,     // how to create
+                              FILE_FLAG_BACKUP_SEMANTICS,  // file attributes
+                              nullptr);
+
+  if (file == INVALID_HANDLE_VALUE) {
+    return ConvertWinError(GetLastError());
+  }
+
+  FILETIME ft;
+  SYSTEMTIME st;
+  PRExplodedTime pret;
+
+  // PR_ExplodeTime expects usecs...
+  PR_ExplodeTime(aLastModifiedTime * PR_USEC_PER_MSEC, PR_GMTParameters, &pret);
+  st.wYear            = pret.tm_year;
+  st.wMonth           = pret.tm_month + 1; // Convert start offset -- Win32: Jan=1; NSPR: Jan=0
+  st.wDayOfWeek       = pret.tm_wday;
+  st.wDay             = pret.tm_mday;
+  st.wHour            = pret.tm_hour;
+  st.wMinute          = pret.tm_min;
+  st.wSecond          = pret.tm_sec;
+  st.wMilliseconds    = pret.tm_usec / 1000;
+
+  nsresult rv = NS_OK;
+  // if at least one of these fails...
+  if (!(SystemTimeToFileTime(&st, &ft) != 0 &&
+        SetFileTime(file, nullptr, &ft, &ft) != 0)) {
+    rv = ConvertWinError(GetLastError());
+  }
+
+  CloseHandle(file);
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetPermissions(uint32_t* aPermissions)
+{
+  if (NS_WARN_IF(!aPermissions)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // get the permissions of the target as determined by mFollowSymlinks
+  // If true, then this will be for the target of the shortcut file,
+  // otherwise it will be for the shortcut file itself (i.e. the same
+  // results as GetPermissionsOfLink)
+  nsresult rv = ResolveAndStat();
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  bool isWritable, isExecutable;
+  IsWritable(&isWritable);
+  IsExecutable(&isExecutable);
+
+  *aPermissions = PR_IRUSR | PR_IRGRP | PR_IROTH;     // all read
+  if (isWritable) {
+    *aPermissions |= PR_IWUSR | PR_IWGRP | PR_IWOTH;  // all write
+  }
+  if (isExecutable) {
+    *aPermissions |= PR_IXUSR | PR_IXGRP | PR_IXOTH;  // all execute
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetPermissionsOfLink(uint32_t* aPermissions)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  if (NS_WARN_IF(!aPermissions)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // The caller is assumed to have already called IsSymlink
+  // and to have found that this file is a link. It is not
+  // possible for a link file to be executable.
+
+  DWORD word = ::GetFileAttributesW(mWorkingPath.get());
+  if (word == INVALID_FILE_ATTRIBUTES) {
+    return NS_ERROR_FILE_INVALID_PATH;
+  }
+
+  bool isWritable = !(word & FILE_ATTRIBUTE_READONLY);
+  *aPermissions = PR_IRUSR | PR_IRGRP | PR_IROTH;     // all read
+  if (isWritable) {
+    *aPermissions |= PR_IWUSR | PR_IWGRP | PR_IWOTH;  // all write
+  }
+
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::SetPermissions(uint32_t aPermissions)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  // set the permissions of the target as determined by mFollowSymlinks
+  // If true, then this will be for the target of the shortcut file,
+  // otherwise it will be for the shortcut file itself (i.e. the same
+  // results as SetPermissionsOfLink)
+  nsresult rv = ResolveAndStat();
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // windows only knows about the following permissions
+  int mode = 0;
+  if (aPermissions & (PR_IRUSR | PR_IRGRP | PR_IROTH)) { // any read
+    mode |= _S_IREAD;
+  }
+  if (aPermissions & (PR_IWUSR | PR_IWGRP | PR_IWOTH)) { // any write
+    mode |= _S_IWRITE;
+  }
+
+  if (_wchmod(mResolvedPath.get(), mode) == -1) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetPermissionsOfLink(uint32_t aPermissions)
+{
+  // The caller is assumed to have already called IsSymlink
+  // and to have found that this file is a link.
+
+  // windows only knows about the following permissions
+  int mode = 0;
+  if (aPermissions & (PR_IRUSR | PR_IRGRP | PR_IROTH)) { // any read
+    mode |= _S_IREAD;
+  }
+  if (aPermissions & (PR_IWUSR | PR_IWGRP | PR_IWOTH)) { // any write
+    mode |= _S_IWRITE;
+  }
+
+  if (_wchmod(mWorkingPath.get(), mode) == -1) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::GetFileSize(int64_t* aFileSize)
+{
+  if (NS_WARN_IF(!aFileSize)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsresult rv = ResolveAndStat();
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  *aFileSize = mFileInfo64.size;
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::GetFileSizeOfLink(int64_t* aFileSize)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  if (NS_WARN_IF(!aFileSize)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // The caller is assumed to have already called IsSymlink
+  // and to have found that this file is a link.
+
+  PRFileInfo64 info;
+  if (NS_FAILED(GetFileInfo(mWorkingPath, &info))) {
+    return NS_ERROR_FILE_INVALID_PATH;
+  }
+
+  *aFileSize = info.size;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetFileSize(int64_t aFileSize)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  nsresult rv = ResolveAndStat();
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  HANDLE hFile = ::CreateFileW(mResolvedPath.get(),// pointer to name of the file
+                               GENERIC_WRITE,      // access (write) mode
+                               FILE_SHARE_READ,    // share mode
+                               nullptr,            // pointer to security attributes
+                               OPEN_EXISTING,          // how to create
+                               FILE_ATTRIBUTE_NORMAL,  // file attributes
+                               nullptr);
+  if (hFile == INVALID_HANDLE_VALUE) {
+    return ConvertWinError(GetLastError());
+  }
+
+  // seek the file pointer to the new, desired end of file
+  // and then truncate the file at that position
+  rv = NS_ERROR_FAILURE;
+  aFileSize = MyFileSeek64(hFile, aFileSize, FILE_BEGIN);
+  if (aFileSize != -1 && SetEndOfFile(hFile)) {
+    MakeDirty();
+    rv = NS_OK;
+  }
+
+  CloseHandle(hFile);
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetDiskSpaceAvailable(int64_t* aDiskSpaceAvailable)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  if (NS_WARN_IF(!aDiskSpaceAvailable)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  ResolveAndStat();
+
+  if (mFileInfo64.type == PR_FILE_FILE) {
+    // Since GetDiskFreeSpaceExW works only on directories, use the parent.
+    nsCOMPtr<nsIFile> parent;
+    if (NS_SUCCEEDED(GetParent(getter_AddRefs(parent))) && parent) {
+      return parent->GetDiskSpaceAvailable(aDiskSpaceAvailable);
+    }
+  }
+
+  ULARGE_INTEGER liFreeBytesAvailableToCaller, liTotalNumberOfBytes;
+  if (::GetDiskFreeSpaceExW(mResolvedPath.get(), &liFreeBytesAvailableToCaller,
+                            &liTotalNumberOfBytes, nullptr)) {
+    *aDiskSpaceAvailable = liFreeBytesAvailableToCaller.QuadPart;
+    return NS_OK;
+  }
+  *aDiskSpaceAvailable = 0;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetParent(nsIFile** aParent)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  if (NS_WARN_IF(!aParent)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // A two-character path must be a drive such as C:, so it has no parent
+  if (mWorkingPath.Length() == 2) {
+    *aParent = nullptr;
+    return NS_OK;
+  }
+
+  int32_t offset = mWorkingPath.RFindChar(char16_t('\\'));
+  // adding this offset check that was removed in bug 241708 fixes mail
+  // directories that aren't relative to/underneath the profile dir.
+  // e.g., on a different drive. Before you remove them, please make
+  // sure local mail directories that aren't underneath the profile dir work.
+  if (offset == kNotFound) {
+    return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+  }
+
+  // A path of the form \\NAME is a top-level path and has no parent
+  if (offset == 1 && mWorkingPath[0] == L'\\') {
+    *aParent = nullptr;
+    return NS_OK;
+  }
+
+  nsAutoString parentPath(mWorkingPath);
+
+  if (offset > 0) {
+    parentPath.Truncate(offset);
+  } else {
+    parentPath.AssignLiteral("\\\\.");
+  }
+
+  nsCOMPtr<nsIFile> localFile;
+  nsresult rv = NS_NewLocalFile(parentPath, mFollowSymlinks,
+                                getter_AddRefs(localFile));
+
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  localFile.forget(aParent);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::Exists(bool* aResult)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  *aResult = false;
+
+  MakeDirty();
+  nsresult rv = ResolveAndStat();
+  *aResult = NS_SUCCEEDED(rv) || rv == NS_ERROR_FILE_IS_LOCKED;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::IsWritable(bool* aIsWritable)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  // The read-only attribute on a FAT directory only means that it can't
+  // be deleted. It is still possible to modify the contents of the directory.
+  nsresult rv = IsDirectory(aIsWritable);
+  if (rv == NS_ERROR_FILE_ACCESS_DENIED) {
+    *aIsWritable = true;
+    return NS_OK;
+  } else if (rv == NS_ERROR_FILE_IS_LOCKED) {
+    // If the file is normally allowed write access
+    // we should still return that the file is writable.
+  } else if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (*aIsWritable) {
+    return NS_OK;
+  }
+
+  // writable if the file doesn't have the readonly attribute
+  rv = HasFileAttribute(FILE_ATTRIBUTE_READONLY, aIsWritable);
+  if (rv == NS_ERROR_FILE_ACCESS_DENIED) {
+    *aIsWritable = false;
+    return NS_OK;
+  } else if (rv == NS_ERROR_FILE_IS_LOCKED) {
+    // If the file is normally allowed write access
+    // we should still return that the file is writable.
+  } else if (NS_FAILED(rv)) {
+    return rv;
+  }
+  *aIsWritable = !*aIsWritable;
+
+  // If the read only attribute is not set, check to make sure
+  // we can open the file with write access.
+  if (*aIsWritable) {
+    PRFileDesc* file;
+    rv = OpenFile(mResolvedPath, PR_WRONLY, 0, false, &file);
+    if (NS_SUCCEEDED(rv)) {
+      PR_Close(file);
+    } else if (rv == NS_ERROR_FILE_ACCESS_DENIED) {
+      *aIsWritable = false;
+    } else if (rv == NS_ERROR_FILE_IS_LOCKED) {
+      // If it is locked and read only we would have
+      // gotten access denied
+      *aIsWritable = true;
+    } else {
+      return rv;
+    }
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::IsReadable(bool* aResult)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  *aResult = false;
+
+  nsresult rv = ResolveAndStat();
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  *aResult = true;
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::IsExecutable(bool* aResult)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  *aResult = false;
+
+  nsresult rv;
+
+  // only files can be executables
+  bool isFile;
+  rv = IsFile(&isFile);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (!isFile) {
+    return NS_OK;
+  }
+
+  //TODO: shouldn't we be checking mFollowSymlinks here?
+  bool symLink;
+  rv = IsSymlink(&symLink);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  nsAutoString path;
+  if (symLink) {
+    GetTarget(path);
+  } else {
+    GetPath(path);
+  }
+
+  // kill trailing dots and spaces.
+  int32_t filePathLen = path.Length() - 1;
+  while (filePathLen > 0 && (path[filePathLen] == L' ' ||
+                             path[filePathLen] == L'.')) {
+    path.Truncate(filePathLen--);
+  }
+
+  // Get extension.
+  int32_t dotIdx = path.RFindChar(char16_t('.'));
+  if (dotIdx != kNotFound) {
+    // Convert extension to lower case.
+    char16_t* p = path.BeginWriting();
+    for (p += dotIdx + 1; *p; ++p) {
+      *p += (*p >= L'A' && *p <= L'Z') ? 'a' - 'A' : 0;
+    }
+
+    // Search for any of the set of executable extensions.
+    static const char* const executableExts[] = {
+      "ad",
+      "ade",         // access project extension
+      "adp",
+      "air",         // Adobe AIR installer
+      "app",         // executable application
+      "application", // from bug 348763
+      "asp",
+      "bas",
+      "bat",
+      "chm",
+      "cmd",
+      "com",
+      "cpl",
+      "crt",
+      "exe",
+      "fxp",         // FoxPro compiled app
+      "hlp",
+      "hta",
+      "inf",
+      "ins",
+      "isp",
+      "jar",         // java application bundle
+      "js",
+      "jse",
+      "lnk",
+      "mad",         // Access Module Shortcut
+      "maf",         // Access
+      "mag",         // Access Diagram Shortcut
+      "mam",         // Access Macro Shortcut
+      "maq",         // Access Query Shortcut
+      "mar",         // Access Report Shortcut
+      "mas",         // Access Stored Procedure
+      "mat",         // Access Table Shortcut
+      "mau",         // Media Attachment Unit
+      "mav",         // Access View Shortcut
+      "maw",         // Access Data Access Page
+      "mda",         // Access Add-in, MDA Access 2 Workgroup
+      "mdb",
+      "mde",
+      "mdt",         // Access Add-in Data
+      "mdw",         // Access Workgroup Information
+      "mdz",         // Access Wizard Template
+      "msc",
+      "msh",         // Microsoft Shell
+      "mshxml",      // Microsoft Shell
+      "msi",
+      "msp",
+      "mst",
+      "ops",         // Office Profile Settings
+      "pcd",
+      "pif",
+      "plg",         // Developer Studio Build Log
+      "prf",         // windows system file
+      "prg",
+      "pst",
+      "reg",
+      "scf",         // Windows explorer command
+      "scr",
+      "sct",
+      "shb",
+      "shs",
+      "url",
+      "vb",
+      "vbe",
+      "vbs",
+      "vsd",
+      "vsmacros",    // Visual Studio .NET Binary-based Macro Project
+      "vss",
+      "vst",
+      "vsw",
+      "ws",
+      "wsc",
+      "wsf",
+      "wsh"
+    };
+    nsDependentSubstring ext = Substring(path, dotIdx + 1);
+    for (size_t i = 0; i < ArrayLength(executableExts); ++i) {
+      if (ext.EqualsASCII(executableExts[i])) {
+        // Found a match.  Set result and quit.
+        *aResult = true;
+        break;
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::IsDirectory(bool* aResult)
+{
+  return HasFileAttribute(FILE_ATTRIBUTE_DIRECTORY, aResult);
+}
+
+NS_IMETHODIMP
+nsLocalFile::IsFile(bool* aResult)
+{
+  nsresult rv = HasFileAttribute(FILE_ATTRIBUTE_DIRECTORY, aResult);
+  if (NS_SUCCEEDED(rv)) {
+    *aResult = !*aResult;
+  }
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::IsHidden(bool* aResult)
+{
+  return HasFileAttribute(FILE_ATTRIBUTE_HIDDEN, aResult);
+}
+
+nsresult
+nsLocalFile::HasFileAttribute(DWORD aFileAttrib, bool* aResult)
+{
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsresult rv = Resolve();
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  DWORD attributes = GetFileAttributesW(mResolvedPath.get());
+  if (INVALID_FILE_ATTRIBUTES == attributes) {
+    return ConvertWinError(GetLastError());
+  }
+
+  *aResult = ((attributes & aFileAttrib) != 0);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::IsSymlink(bool* aResult)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // unless it is a valid shortcut path it's not a symlink
+  if (!IsShortcutPath(mWorkingPath)) {
+    *aResult = false;
+    return NS_OK;
+  }
+
+  // we need to know if this is a file or directory
+  nsresult rv = ResolveAndStat();
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // We should not check mFileInfo64.type here for PR_FILE_FILE because lnk
+  // files can point to directories or files.  Important security checks
+  // depend on correctly identifying lnk files.  mFileInfo64 now holds info
+  // about the target of the lnk file, not the actual lnk file!
+  *aResult = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::IsSpecial(bool* aResult)
+{
+  return HasFileAttribute(FILE_ATTRIBUTE_SYSTEM, aResult);
+}
+
+NS_IMETHODIMP
+nsLocalFile::Equals(nsIFile* aInFile, bool* aResult)
+{
+  if (NS_WARN_IF(!aInFile)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  if (NS_WARN_IF(!aResult)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  EnsureShortPath();
+
+  nsCOMPtr<nsILocalFileWin> lf(do_QueryInterface(aInFile));
+  if (!lf) {
+    *aResult = false;
+    return NS_OK;
+  }
+
+  nsAutoString inFilePath;
+  lf->GetCanonicalPath(inFilePath);
+
+  // Ok : Win9x
+  *aResult = _wcsicmp(mShortWorkingPath.get(), inFilePath.get()) == 0;
+
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::Contains(nsIFile* aInFile, bool* aResult)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  *aResult = false;
+
+  nsAutoString myFilePath;
+  if (NS_FAILED(GetTarget(myFilePath))) {
+    GetPath(myFilePath);
+  }
+
+  uint32_t myFilePathLen = myFilePath.Length();
+
+  nsAutoString inFilePath;
+  if (NS_FAILED(aInFile->GetTarget(inFilePath))) {
+    aInFile->GetPath(inFilePath);
+  }
+
+  // make sure that the |aInFile|'s path has a trailing separator.
+  if (inFilePath.Length() >= myFilePathLen &&
+      inFilePath[myFilePathLen] == L'\\') {
+    if (_wcsnicmp(myFilePath.get(), inFilePath.get(), myFilePathLen) == 0) {
+      *aResult = true;
+    }
+
+  }
+
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::GetTarget(nsAString& aResult)
+{
+  aResult.Truncate();
+#if STRICT_FAKE_SYMLINKS
+  bool symLink;
+
+  nsresult rv = IsSymlink(&symLink);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (!symLink) {
+    return NS_ERROR_FILE_INVALID_PATH;
+  }
+#endif
+  ResolveAndStat();
+
+  aResult = mResolvedPath;
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::GetFollowLinks(bool* aFollowLinks)
+{
+  *aFollowLinks = mFollowSymlinks;
+  return NS_OK;
+}
+NS_IMETHODIMP
+nsLocalFile::SetFollowLinks(bool aFollowLinks)
+{
+  MakeDirty();
+  mFollowSymlinks = aFollowLinks;
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::GetDirectoryEntries(nsISimpleEnumerator** aEntries)
+{
+  nsresult rv;
+
+  *aEntries = nullptr;
+  if (mWorkingPath.EqualsLiteral("\\\\.")) {
+    RefPtr<nsDriveEnumerator> drives = new nsDriveEnumerator;
+    rv = drives->Init();
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+    drives.forget(aEntries);
+    return NS_OK;
+  }
+
+  RefPtr<nsDirEnumerator> dirEnum = new nsDirEnumerator();
+  rv = dirEnum->Init(this);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  dirEnum.forget(aEntries);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetPersistentDescriptor(nsACString& aPersistentDescriptor)
+{
+  CopyUTF16toUTF8(mWorkingPath, aPersistentDescriptor);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetPersistentDescriptor(const nsACString& aPersistentDescriptor)
+{
+  if (IsUTF8(aPersistentDescriptor)) {
+    return InitWithPath(NS_ConvertUTF8toUTF16(aPersistentDescriptor));
+  } else {
+    return InitWithNativePath(aPersistentDescriptor);
+  }
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetFileAttributesWin(uint32_t* aAttribs)
+{
+  *aAttribs = 0;
+  DWORD dwAttrs = GetFileAttributesW(mWorkingPath.get());
+  if (dwAttrs == INVALID_FILE_ATTRIBUTES) {
+    return NS_ERROR_FILE_INVALID_PATH;
+  }
+
+  if (!(dwAttrs & FILE_ATTRIBUTE_NOT_CONTENT_INDEXED)) {
+    *aAttribs |= WFA_SEARCH_INDEXED;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetFileAttributesWin(uint32_t aAttribs)
+{
+  DWORD dwAttrs = GetFileAttributesW(mWorkingPath.get());
+  if (dwAttrs == INVALID_FILE_ATTRIBUTES) {
+    return NS_ERROR_FILE_INVALID_PATH;
+  }
+
+  if (aAttribs & WFA_SEARCH_INDEXED) {
+    dwAttrs &= ~FILE_ATTRIBUTE_NOT_CONTENT_INDEXED;
+  } else {
+    dwAttrs |= FILE_ATTRIBUTE_NOT_CONTENT_INDEXED;
+  }
+
+  if (aAttribs & WFA_READONLY) {
+    dwAttrs |= FILE_ATTRIBUTE_READONLY;
+  } else if ((aAttribs & WFA_READWRITE) &&
+             (dwAttrs & FILE_ATTRIBUTE_READONLY)) {
+    dwAttrs &= ~FILE_ATTRIBUTE_READONLY;
+  }
+
+  if (SetFileAttributesW(mWorkingPath.get(), dwAttrs) == 0) {
+    return NS_ERROR_FAILURE;
+  }
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::Reveal()
+{
+  // This API should be main thread only
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // make sure mResolvedPath is set
+  nsresult rv = Resolve();
+  if (NS_FAILED(rv) && rv != NS_ERROR_FILE_NOT_FOUND) {
+    return rv;
+  }
+
+  // To create a new thread, get the thread manager
+  nsCOMPtr<nsIThreadManager> tm = do_GetService(NS_THREADMANAGER_CONTRACTID);
+  nsCOMPtr<nsIThread> mythread;
+  rv = tm->NewThread(0, 0, getter_AddRefs(mythread));
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  nsCOMPtr<nsIRunnable> runnable = new AsyncRevealOperation(mResolvedPath);
+
+  // After the dispatch, the result runnable will shut down the worker
+  // thread, so we can let it go.
+  mythread->Dispatch(runnable, NS_DISPATCH_NORMAL);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::Launch()
+{
+  // This API should be main thread only
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // make sure mResolvedPath is set
+  nsresult rv = Resolve();
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // use the app registry name to launch a shell execute....
+  SHELLEXECUTEINFOW seinfo;
+  memset(&seinfo, 0, sizeof(seinfo));
+  seinfo.cbSize = sizeof(SHELLEXECUTEINFOW);
+  seinfo.fMask = SEE_MASK_ASYNCOK;
+  seinfo.hwnd = GetMostRecentNavigatorHWND();
+  seinfo.lpVerb = nullptr;
+  seinfo.lpFile = mResolvedPath.get();
+  seinfo.lpParameters = nullptr;
+  seinfo.lpDirectory = nullptr;
+  seinfo.nShow = SW_SHOWNORMAL;
+
+  // Use the directory of the file we're launching as the working
+  // directory. That way if we have a self extracting EXE it won't
+  // suggest to extract to the install directory.
+  WCHAR workingDirectory[MAX_PATH + 1] = { L'\0' };
+  wcsncpy(workingDirectory, mResolvedPath.get(), MAX_PATH);
+  if (PathRemoveFileSpecW(workingDirectory)) {
+    seinfo.lpDirectory = workingDirectory;
+  } else {
+    NS_WARNING("Could not set working directory for launched file.");
+  }
+
+  if (ShellExecuteExW(&seinfo)) {
+    return NS_OK;
+  }
+  DWORD r = GetLastError();
+  // if the file has no association, we launch windows'
+  // "what do you want to do" dialog
+  if (r == SE_ERR_NOASSOC) {
+    nsAutoString shellArg;
+    shellArg.AssignLiteral(u"shell32.dll,OpenAs_RunDLL ");
+    shellArg.Append(mResolvedPath);
+    seinfo.lpFile = L"RUNDLL32.EXE";
+    seinfo.lpParameters = shellArg.get();
+    if (ShellExecuteExW(&seinfo)) {
+      return NS_OK;
+    }
+    r = GetLastError();
+  }
+  if (r < 32) {
+    switch (r) {
+      case 0:
+      case SE_ERR_OOM:
+        return NS_ERROR_OUT_OF_MEMORY;
+      case ERROR_FILE_NOT_FOUND:
+        return NS_ERROR_FILE_NOT_FOUND;
+      case ERROR_PATH_NOT_FOUND:
+        return NS_ERROR_FILE_UNRECOGNIZED_PATH;
+      case ERROR_BAD_FORMAT:
+        return NS_ERROR_FILE_CORRUPTED;
+      case SE_ERR_ACCESSDENIED:
+        return NS_ERROR_FILE_ACCESS_DENIED;
+      case SE_ERR_ASSOCINCOMPLETE:
+      case SE_ERR_NOASSOC:
+        return NS_ERROR_UNEXPECTED;
+      case SE_ERR_DDEBUSY:
+      case SE_ERR_DDEFAIL:
+      case SE_ERR_DDETIMEOUT:
+        return NS_ERROR_NOT_AVAILABLE;
+      case SE_ERR_DLLNOTFOUND:
+        return NS_ERROR_FAILURE;
+      case SE_ERR_SHARE:
+        return NS_ERROR_FILE_IS_LOCKED;
+      default:
+        return NS_ERROR_FILE_EXECUTION_FAILED;
+    }
+  }
+  return NS_OK;
+}
+
+nsresult
+NS_NewLocalFile(const nsAString& aPath, bool aFollowLinks, nsIFile** aResult)
+{
+  RefPtr<nsLocalFile> file = new nsLocalFile();
+
+  file->SetFollowLinks(aFollowLinks);
+
+  if (!aPath.IsEmpty()) {
+    nsresult rv = file->InitWithPath(aPath);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+  }
+
+  file.forget(aResult);
+  return NS_OK;
+}
+
+//-----------------------------------------------------------------------------
+// Native (lossy) interface
+//-----------------------------------------------------------------------------
+
+NS_IMETHODIMP
+nsLocalFile::InitWithNativePath(const nsACString& aFilePath)
+{
+  nsAutoString tmp;
+  nsresult rv = NS_CopyNativeToUnicode(aFilePath, tmp);
+  if (NS_SUCCEEDED(rv)) {
+    return InitWithPath(tmp);
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::AppendNative(const nsACString& aNode)
+{
+  nsAutoString tmp;
+  nsresult rv = NS_CopyNativeToUnicode(aNode, tmp);
+  if (NS_SUCCEEDED(rv)) {
+    return Append(tmp);
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::AppendRelativeNativePath(const nsACString& aNode)
+{
+  nsAutoString tmp;
+  nsresult rv = NS_CopyNativeToUnicode(aNode, tmp);
+  if (NS_SUCCEEDED(rv)) {
+    return AppendRelativePath(tmp);
+  }
+  return rv;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::GetNativeLeafName(nsACString& aLeafName)
+{
+  //NS_WARNING("This API is lossy. Use GetLeafName !");
+  nsAutoString tmp;
+  nsresult rv = GetLeafName(tmp);
+  if (NS_SUCCEEDED(rv)) {
+    rv = NS_CopyUnicodeToNative(tmp, aLeafName);
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetNativeLeafName(const nsACString& aLeafName)
+{
+  nsAutoString tmp;
+  nsresult rv = NS_CopyNativeToUnicode(aLeafName, tmp);
+  if (NS_SUCCEEDED(rv)) {
+    return SetLeafName(tmp);
+  }
+
+  return rv;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::GetNativePath(nsACString& aResult)
+{
+  //NS_WARNING("This API is lossy. Use GetPath !");
+  nsAutoString tmp;
+  nsresult rv = GetPath(tmp);
+  if (NS_SUCCEEDED(rv)) {
+    rv = NS_CopyUnicodeToNative(tmp, aResult);
+  }
+
+  return rv;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::GetNativeCanonicalPath(nsACString& aResult)
+{
+  NS_WARNING("This method is lossy. Use GetCanonicalPath !");
+  EnsureShortPath();
+  NS_CopyUnicodeToNative(mShortWorkingPath, aResult);
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsLocalFile::CopyToNative(nsIFile* aNewParentDir, const nsACString& aNewName)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  if (aNewName.IsEmpty()) {
+    return CopyTo(aNewParentDir, EmptyString());
+  }
+
+  nsAutoString tmp;
+  nsresult rv = NS_CopyNativeToUnicode(aNewName, tmp);
+  if (NS_SUCCEEDED(rv)) {
+    return CopyTo(aNewParentDir, tmp);
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::CopyToFollowingLinksNative(nsIFile* aNewParentDir,
+                                        const nsACString& aNewName)
+{
+  if (aNewName.IsEmpty()) {
+    return CopyToFollowingLinks(aNewParentDir, EmptyString());
+  }
+
+  nsAutoString tmp;
+  nsresult rv = NS_CopyNativeToUnicode(aNewName, tmp);
+  if (NS_SUCCEEDED(rv)) {
+    return CopyToFollowingLinks(aNewParentDir, tmp);
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::MoveToNative(nsIFile* aNewParentDir, const nsACString& aNewName)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  if (aNewName.IsEmpty()) {
+    return MoveTo(aNewParentDir, EmptyString());
+  }
+
+  nsAutoString tmp;
+  nsresult rv = NS_CopyNativeToUnicode(aNewName, tmp);
+  if (NS_SUCCEEDED(rv)) {
+    return MoveTo(aNewParentDir, tmp);
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetNativeTarget(nsACString& aResult)
+{
+  // Check we are correctly initialized.
+  CHECK_mWorkingPath();
+
+  NS_WARNING("This API is lossy. Use GetTarget !");
+  nsAutoString tmp;
+  nsresult rv = GetTarget(tmp);
+  if (NS_SUCCEEDED(rv)) {
+    rv = NS_CopyUnicodeToNative(tmp, aResult);
+  }
+
+  return rv;
+}
+
+nsresult
+NS_NewNativeLocalFile(const nsACString& aPath, bool aFollowLinks,
+                      nsIFile** aResult)
+{
+  nsAutoString buf;
+  nsresult rv = NS_CopyNativeToUnicode(aPath, buf);
+  if (NS_FAILED(rv)) {
+    *aResult = nullptr;
+    return rv;
+  }
+  return NS_NewLocalFile(buf, aFollowLinks, aResult);
+}
+
+void
+nsLocalFile::EnsureShortPath()
+{
+  if (!mShortWorkingPath.IsEmpty()) {
+    return;
+  }
+
+  WCHAR shortPath[MAX_PATH + 1];
+  DWORD lengthNeeded = ::GetShortPathNameW(mWorkingPath.get(), shortPath,
+                                           ArrayLength(shortPath));
+  // If an error occurred then lengthNeeded is set to 0 or the length of the
+  // needed buffer including null termination.  If it succeeds the number of
+  // wide characters not including null termination is returned.
+  if (lengthNeeded != 0 && lengthNeeded < ArrayLength(shortPath)) {
+    mShortWorkingPath.Assign(shortPath);
+  } else {
+    mShortWorkingPath.Assign(mWorkingPath);
+  }
+}
+
+// nsIHashable
+
+NS_IMETHODIMP
+nsLocalFile::Equals(nsIHashable* aOther, bool* aResult)
+{
+  nsCOMPtr<nsIFile> otherfile(do_QueryInterface(aOther));
+  if (!otherfile) {
+    *aResult = false;
+    return NS_OK;
+  }
+
+  return Equals(otherfile, aResult);
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetHashCode(uint32_t* aResult)
+{
+  // In order for short and long path names to hash to the same value we
+  // always hash on the short pathname.
+  EnsureShortPath();
+
+  *aResult = HashString(mShortWorkingPath);
+  return NS_OK;
+}
+
+//-----------------------------------------------------------------------------
+// nsLocalFile <static members>
+//-----------------------------------------------------------------------------
+
+void
+nsLocalFile::GlobalInit()
+{
+  DebugOnly<nsresult> rv = NS_CreateShortcutResolver();
+  NS_ASSERTION(NS_SUCCEEDED(rv), "Shortcut resolver could not be created");
+}
+
+void
+nsLocalFile::GlobalShutdown()
+{
+  NS_DestroyShortcutResolver();
+}
+
+NS_IMPL_ISUPPORTS(nsDriveEnumerator, nsISimpleEnumerator)
+
+nsDriveEnumerator::nsDriveEnumerator()
+{
+}
+
+nsDriveEnumerator::~nsDriveEnumerator()
+{
+}
+
+nsresult
+nsDriveEnumerator::Init()
+{
+  /* If the length passed to GetLogicalDriveStrings is smaller
+   * than the length of the string it would return, it returns
+   * the length required for the string. */
+  DWORD length = GetLogicalDriveStringsW(0, 0);
+  /* The string is null terminated */
+  if (!mDrives.SetLength(length + 1, fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  if (!GetLogicalDriveStringsW(length, wwc(mDrives.BeginWriting()))) {
+    return NS_ERROR_FAILURE;
+  }
+  mDrives.BeginReading(mStartOfCurrentDrive);
+  mDrives.EndReading(mEndOfDrivesString);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDriveEnumerator::HasMoreElements(bool* aHasMore)
+{
+  *aHasMore = *mStartOfCurrentDrive != L'\0';
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDriveEnumerator::GetNext(nsISupports** aNext)
+{
+  /* GetLogicalDrives stored in mDrives is a concatenation
+   * of null terminated strings, followed by a null terminator.
+   * mStartOfCurrentDrive is an iterator pointing at the first
+   * character of the current drive. */
+  if (*mStartOfCurrentDrive == L'\0') {
+    *aNext = nullptr;
+    return NS_OK;
+  }
+
+  nsAString::const_iterator driveEnd = mStartOfCurrentDrive;
+  FindCharInReadable(L'\0', driveEnd, mEndOfDrivesString);
+  nsString drive(Substring(mStartOfCurrentDrive, driveEnd));
+  mStartOfCurrentDrive = ++driveEnd;
+
+  nsIFile* file;
+  nsresult rv = NS_NewLocalFile(drive, false, &file);
+
+  *aNext = file;
+  return rv;
+}
diff --git a/xpcom/io/nsLocalFileWin.h b/xpcom/io/nsLocalFileWin.h
new file mode 100644
index 000000000..abef2c106
--- /dev/null
+++ b/xpcom/io/nsLocalFileWin.h
@@ -0,0 +1,123 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef _nsLocalFileWIN_H_
+#define _nsLocalFileWIN_H_
+
+#include "nscore.h"
+#include "nsError.h"
+#include "nsString.h"
+#include "nsCRT.h"
+#include "nsIFile.h"
+#include "nsIFactory.h"
+#include "nsILocalFileWin.h"
+#include "nsIHashable.h"
+#include "nsIClassInfoImpl.h"
+#include "prio.h"
+
+#include "mozilla/Attributes.h"
+
+#include "windows.h"
+#include "shlobj.h"
+
+#include <sys/stat.h>
+
+class nsLocalFile final
+  : public nsILocalFileWin
+  , public nsIHashable
+{
+public:
+  NS_DEFINE_STATIC_CID_ACCESSOR(NS_LOCAL_FILE_CID)
+
+  nsLocalFile();
+
+  static nsresult nsLocalFileConstructor(nsISupports* aOuter,
+                                         const nsIID& aIID,
+                                         void** aInstancePtr);
+
+  // nsISupports interface
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  // nsIFile interface
+  NS_DECL_NSIFILE
+
+  // nsILocalFile interface
+  NS_DECL_NSILOCALFILE
+
+  // nsILocalFileWin interface
+  NS_DECL_NSILOCALFILEWIN
+
+  // nsIHashable interface
+  NS_DECL_NSIHASHABLE
+
+public:
+  static void GlobalInit();
+  static void GlobalShutdown();
+
+  // Removes registry command handler parameters, quotes, and expands environment strings.
+  static bool CleanupCmdHandlerPath(nsAString& aCommandHandler);
+
+private:
+  // CopyMove and CopySingleFile constants for |options| parameter:
+  enum CopyFileOption {
+    FollowSymlinks          = 1u << 0,
+    Move                    = 1u << 1,
+    SkipNtfsAclReset        = 1u << 2,
+    Rename                  = 1u << 3
+  };
+
+  nsLocalFile(const nsLocalFile& aOther);
+  ~nsLocalFile()
+  {
+  }
+
+  bool mDirty;            // cached information can only be used when this is false
+  bool mResolveDirty;
+  bool mFollowSymlinks;   // should we follow symlinks when working on this file
+
+  // this string will always be in native format!
+  nsString mWorkingPath;
+
+  // this will be the resolved path of shortcuts, it will *NEVER*
+  // be returned to the user
+  nsString mResolvedPath;
+
+  // this string, if not empty, is the *short* pathname that represents
+  // mWorkingPath
+  nsString mShortWorkingPath;
+
+  PRFileInfo64 mFileInfo64;
+
+  void MakeDirty()
+  {
+    mDirty = true;
+    mResolveDirty = true;
+    mShortWorkingPath.Truncate();
+  }
+
+  nsresult ResolveAndStat();
+  nsresult Resolve();
+  nsresult ResolveShortcut();
+
+  void EnsureShortPath();
+
+  nsresult CopyMove(nsIFile* aNewParentDir, const nsAString& aNewName,
+                    uint32_t aOptions);
+  nsresult CopySingleFile(nsIFile* aSource, nsIFile* aDest,
+                          const nsAString& aNewName, uint32_t aOptions);
+
+  nsresult SetModDate(int64_t aLastModifiedTime, const wchar_t* aFilePath);
+  nsresult HasFileAttribute(DWORD aFileAttrib, bool* aResult);
+  nsresult AppendInternal(const nsAFlatString& aNode,
+                          bool aMultipleComponents);
+
+  nsresult OpenNSPRFileDescMaybeShareDelete(int32_t aFlags,
+                                            int32_t aMode,
+                                            bool aShareDelete,
+                                            PRFileDesc** aResult);
+};
+
+#endif
diff --git a/xpcom/io/nsMultiplexInputStream.cpp b/xpcom/io/nsMultiplexInputStream.cpp
new file mode 100644
index 000000000..4aa397c37
--- /dev/null
+++ b/xpcom/io/nsMultiplexInputStream.cpp
@@ -0,0 +1,835 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * The multiplex stream concatenates a list of input streams into a single
+ * stream.
+ */
+
+#include "mozilla/Attributes.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/Mutex.h"
+
+#include "base/basictypes.h"
+
+#include "nsMultiplexInputStream.h"
+#include "nsICloneableInputStream.h"
+#include "nsIMultiplexInputStream.h"
+#include "nsISeekableStream.h"
+#include "nsCOMPtr.h"
+#include "nsCOMArray.h"
+#include "nsIClassInfoImpl.h"
+#include "nsIIPCSerializableInputStream.h"
+#include "mozilla/ipc/InputStreamUtils.h"
+
+using namespace mozilla;
+using namespace mozilla::ipc;
+
+using mozilla::DeprecatedAbs;
+using mozilla::Maybe;
+using mozilla::Nothing;
+using mozilla::Some;
+
+class nsMultiplexInputStream final
+  : public nsIMultiplexInputStream
+  , public nsISeekableStream
+  , public nsIIPCSerializableInputStream
+  , public nsICloneableInputStream
+{
+public:
+  nsMultiplexInputStream();
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIINPUTSTREAM
+  NS_DECL_NSIMULTIPLEXINPUTSTREAM
+  NS_DECL_NSISEEKABLESTREAM
+  NS_DECL_NSIIPCSERIALIZABLEINPUTSTREAM
+  NS_DECL_NSICLONEABLEINPUTSTREAM
+
+private:
+  ~nsMultiplexInputStream()
+  {
+  }
+
+  struct MOZ_STACK_CLASS ReadSegmentsState
+  {
+    nsCOMPtr<nsIInputStream> mThisStream;
+    uint32_t mOffset;
+    nsWriteSegmentFun mWriter;
+    void* mClosure;
+    bool mDone;
+  };
+
+  static nsresult ReadSegCb(nsIInputStream* aIn, void* aClosure,
+                            const char* aFromRawSegment, uint32_t aToOffset,
+                            uint32_t aCount, uint32_t* aWriteCount);
+
+  Mutex mLock; // Protects access to all data members.
+  nsTArray<nsCOMPtr<nsIInputStream>> mStreams;
+  uint32_t mCurrentStream;
+  bool mStartedReadingCurrent;
+  nsresult mStatus;
+};
+
+NS_IMPL_ADDREF(nsMultiplexInputStream)
+NS_IMPL_RELEASE(nsMultiplexInputStream)
+
+NS_IMPL_CLASSINFO(nsMultiplexInputStream, nullptr, nsIClassInfo::THREADSAFE,
+                  NS_MULTIPLEXINPUTSTREAM_CID)
+
+NS_IMPL_QUERY_INTERFACE_CI(nsMultiplexInputStream,
+                           nsIMultiplexInputStream,
+                           nsIInputStream,
+                           nsISeekableStream,
+                           nsIIPCSerializableInputStream,
+                           nsICloneableInputStream)
+NS_IMPL_CI_INTERFACE_GETTER(nsMultiplexInputStream,
+                            nsIMultiplexInputStream,
+                            nsIInputStream,
+                            nsISeekableStream)
+
+static nsresult
+AvailableMaybeSeek(nsIInputStream* aStream, uint64_t* aResult)
+{
+  nsresult rv = aStream->Available(aResult);
+  if (rv == NS_BASE_STREAM_CLOSED) {
+    // Blindly seek to the current position if Available() returns
+    // NS_BASE_STREAM_CLOSED.
+    // If nsIFileInputStream is closed in Read() due to CLOSE_ON_EOF flag,
+    // Seek() could reopen the file if REOPEN_ON_REWIND flag is set.
+    nsCOMPtr<nsISeekableStream> seekable = do_QueryInterface(aStream);
+    if (seekable) {
+      nsresult rvSeek = seekable->Seek(nsISeekableStream::NS_SEEK_CUR, 0);
+      if (NS_SUCCEEDED(rvSeek)) {
+        rv = aStream->Available(aResult);
+      }
+    }
+  }
+  return rv;
+}
+
+static nsresult
+TellMaybeSeek(nsISeekableStream* aSeekable, int64_t* aResult)
+{
+  nsresult rv = aSeekable->Tell(aResult);
+  if (rv == NS_BASE_STREAM_CLOSED) {
+    // Blindly seek to the current position if Tell() returns
+    // NS_BASE_STREAM_CLOSED.
+    // If nsIFileInputStream is closed in Read() due to CLOSE_ON_EOF flag,
+    // Seek() could reopen the file if REOPEN_ON_REWIND flag is set.
+    nsresult rvSeek = aSeekable->Seek(nsISeekableStream::NS_SEEK_CUR, 0);
+    if (NS_SUCCEEDED(rvSeek)) {
+      rv = aSeekable->Tell(aResult);
+    }
+  }
+  return rv;
+}
+
+nsMultiplexInputStream::nsMultiplexInputStream()
+  : mLock("nsMultiplexInputStream lock"),
+    mCurrentStream(0),
+    mStartedReadingCurrent(false),
+    mStatus(NS_OK)
+{
+}
+
+NS_IMETHODIMP
+nsMultiplexInputStream::GetCount(uint32_t* aCount)
+{
+  MutexAutoLock lock(mLock);
+  *aCount = mStreams.Length();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMultiplexInputStream::AppendStream(nsIInputStream* aStream)
+{
+  MutexAutoLock lock(mLock);
+  return mStreams.AppendElement(aStream) ? NS_OK : NS_ERROR_OUT_OF_MEMORY;
+}
+
+NS_IMETHODIMP
+nsMultiplexInputStream::InsertStream(nsIInputStream* aStream, uint32_t aIndex)
+{
+  MutexAutoLock lock(mLock);
+  mStreams.InsertElementAt(aIndex, aStream);
+  if (mCurrentStream > aIndex ||
+      (mCurrentStream == aIndex && mStartedReadingCurrent)) {
+    ++mCurrentStream;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMultiplexInputStream::RemoveStream(uint32_t aIndex)
+{
+  MutexAutoLock lock(mLock);
+  mStreams.RemoveElementAt(aIndex);
+  if (mCurrentStream > aIndex) {
+    --mCurrentStream;
+  } else if (mCurrentStream == aIndex) {
+    mStartedReadingCurrent = false;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMultiplexInputStream::GetStream(uint32_t aIndex, nsIInputStream** aResult)
+{
+  MutexAutoLock lock(mLock);
+  *aResult = mStreams.SafeElementAt(aIndex, nullptr);
+  if (NS_WARN_IF(!*aResult)) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  NS_ADDREF(*aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMultiplexInputStream::Close()
+{
+  MutexAutoLock lock(mLock);
+  mStatus = NS_BASE_STREAM_CLOSED;
+
+  nsresult rv = NS_OK;
+
+  uint32_t len = mStreams.Length();
+  for (uint32_t i = 0; i < len; ++i) {
+    nsresult rv2 = mStreams[i]->Close();
+    // We still want to close all streams, but we should return an error
+    if (NS_FAILED(rv2)) {
+      rv = rv2;
+    }
+  }
+  return rv;
+}
+
+NS_IMETHODIMP
+nsMultiplexInputStream::Available(uint64_t* aResult)
+{
+  MutexAutoLock lock(mLock);
+  if (NS_FAILED(mStatus)) {
+    return mStatus;
+  }
+
+  uint64_t avail = 0;
+
+  uint32_t len = mStreams.Length();
+  for (uint32_t i = mCurrentStream; i < len; i++) {
+    uint64_t streamAvail;
+    mStatus = AvailableMaybeSeek(mStreams[i], &streamAvail);
+    if (NS_WARN_IF(NS_FAILED(mStatus))) {
+      return mStatus;
+    }
+    avail += streamAvail;
+  }
+  *aResult = avail;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMultiplexInputStream::Read(char* aBuf, uint32_t aCount, uint32_t* aResult)
+{
+  MutexAutoLock lock(mLock);
+  // It is tempting to implement this method in terms of ReadSegments, but
+  // that would prevent this class from being used with streams that only
+  // implement Read (e.g., file streams).
+
+  *aResult = 0;
+
+  if (mStatus == NS_BASE_STREAM_CLOSED) {
+    return NS_OK;
+  }
+  if (NS_FAILED(mStatus)) {
+    return mStatus;
+  }
+
+  nsresult rv = NS_OK;
+
+  uint32_t len = mStreams.Length();
+  while (mCurrentStream < len && aCount) {
+    uint32_t read;
+    rv = mStreams[mCurrentStream]->Read(aBuf, aCount, &read);
+
+    // XXX some streams return NS_BASE_STREAM_CLOSED to indicate EOF.
+    // (This is a bug in those stream implementations)
+    if (rv == NS_BASE_STREAM_CLOSED) {
+      NS_NOTREACHED("Input stream's Read method returned NS_BASE_STREAM_CLOSED");
+      rv = NS_OK;
+      read = 0;
+    } else if (NS_FAILED(rv)) {
+      break;
+    }
+
+    if (read == 0) {
+      ++mCurrentStream;
+      mStartedReadingCurrent = false;
+    } else {
+      NS_ASSERTION(aCount >= read, "Read more than requested");
+      *aResult += read;
+      aCount -= read;
+      aBuf += read;
+      mStartedReadingCurrent = true;
+    }
+  }
+  return *aResult ? NS_OK : rv;
+}
+
+NS_IMETHODIMP
+nsMultiplexInputStream::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
+                                     uint32_t aCount, uint32_t* aResult)
+{
+  MutexAutoLock lock(mLock);
+
+  if (mStatus == NS_BASE_STREAM_CLOSED) {
+    *aResult = 0;
+    return NS_OK;
+  }
+  if (NS_FAILED(mStatus)) {
+    return mStatus;
+  }
+
+  NS_ASSERTION(aWriter, "missing aWriter");
+
+  nsresult rv = NS_OK;
+  ReadSegmentsState state;
+  state.mThisStream = this;
+  state.mOffset = 0;
+  state.mWriter = aWriter;
+  state.mClosure = aClosure;
+  state.mDone = false;
+
+  uint32_t len = mStreams.Length();
+  while (mCurrentStream < len && aCount) {
+    uint32_t read;
+    rv = mStreams[mCurrentStream]->ReadSegments(ReadSegCb, &state, aCount, &read);
+
+    // XXX some streams return NS_BASE_STREAM_CLOSED to indicate EOF.
+    // (This is a bug in those stream implementations)
+    if (rv == NS_BASE_STREAM_CLOSED) {
+      NS_NOTREACHED("Input stream's Read method returned NS_BASE_STREAM_CLOSED");
+      rv = NS_OK;
+      read = 0;
+    }
+
+    // if |aWriter| decided to stop reading segments...
+    if (state.mDone || NS_FAILED(rv)) {
+      break;
+    }
+
+    // if stream is empty, then advance to the next stream.
+    if (read == 0) {
+      ++mCurrentStream;
+      mStartedReadingCurrent = false;
+    } else {
+      NS_ASSERTION(aCount >= read, "Read more than requested");
+      state.mOffset += read;
+      aCount -= read;
+      mStartedReadingCurrent = true;
+    }
+  }
+
+  // if we successfully read some data, then this call succeeded.
+  *aResult = state.mOffset;
+  return state.mOffset ? NS_OK : rv;
+}
+
+nsresult
+nsMultiplexInputStream::ReadSegCb(nsIInputStream* aIn, void* aClosure,
+                                  const char* aFromRawSegment,
+                                  uint32_t aToOffset, uint32_t aCount,
+                                  uint32_t* aWriteCount)
+{
+  nsresult rv;
+  ReadSegmentsState* state = (ReadSegmentsState*)aClosure;
+  rv = (state->mWriter)(state->mThisStream,
+                        state->mClosure,
+                        aFromRawSegment,
+                        aToOffset + state->mOffset,
+                        aCount,
+                        aWriteCount);
+  if (NS_FAILED(rv)) {
+    state->mDone = true;
+  }
+  return rv;
+}
+
+NS_IMETHODIMP
+nsMultiplexInputStream::IsNonBlocking(bool* aNonBlocking)
+{
+  MutexAutoLock lock(mLock);
+
+  uint32_t len = mStreams.Length();
+  if (len == 0) {
+    // Claim to be non-blocking, since we won't block the caller.
+    // On the other hand we'll never return NS_BASE_STREAM_WOULD_BLOCK,
+    // so maybe we should claim to be blocking?  It probably doesn't
+    // matter in practice.
+    *aNonBlocking = true;
+    return NS_OK;
+  }
+  for (uint32_t i = 0; i < len; ++i) {
+    nsresult rv = mStreams[i]->IsNonBlocking(aNonBlocking);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+    // If one is non-blocking the entire stream becomes non-blocking
+    // (except that we don't implement nsIAsyncInputStream, so there's
+    //  not much for the caller to do if Read returns "would block")
+    if (*aNonBlocking) {
+      return NS_OK;
+    }
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMultiplexInputStream::Seek(int32_t aWhence, int64_t aOffset)
+{
+  MutexAutoLock lock(mLock);
+
+  if (NS_FAILED(mStatus)) {
+    return mStatus;
+  }
+
+  nsresult rv;
+
+  uint32_t oldCurrentStream = mCurrentStream;
+  bool oldStartedReadingCurrent = mStartedReadingCurrent;
+
+  if (aWhence == NS_SEEK_SET) {
+    int64_t remaining = aOffset;
+    if (aOffset == 0) {
+      mCurrentStream = 0;
+    }
+    for (uint32_t i = 0; i < mStreams.Length(); ++i) {
+      nsCOMPtr<nsISeekableStream> stream =
+        do_QueryInterface(mStreams[i]);
+      if (!stream) {
+        return NS_ERROR_FAILURE;
+      }
+
+      // See if all remaining streams should be rewound
+      if (remaining == 0) {
+        if (i < oldCurrentStream ||
+            (i == oldCurrentStream && oldStartedReadingCurrent)) {
+          rv = stream->Seek(NS_SEEK_SET, 0);
+          if (NS_WARN_IF(NS_FAILED(rv))) {
+            return rv;
+          }
+          continue;
+        } else {
+          break;
+        }
+      }
+
+      // Get position in current stream
+      int64_t streamPos;
+      if (i > oldCurrentStream ||
+          (i == oldCurrentStream && !oldStartedReadingCurrent)) {
+        streamPos = 0;
+      } else {
+        rv = TellMaybeSeek(stream, &streamPos);
+        if (NS_WARN_IF(NS_FAILED(rv))) {
+          return rv;
+        }
+      }
+
+      // See if we need to seek current stream forward or backward
+      if (remaining < streamPos) {
+        rv = stream->Seek(NS_SEEK_SET, remaining);
+        if (NS_WARN_IF(NS_FAILED(rv))) {
+          return rv;
+        }
+
+        mCurrentStream = i;
+        mStartedReadingCurrent = remaining != 0;
+
+        remaining = 0;
+      } else if (remaining > streamPos) {
+        if (i < oldCurrentStream) {
+          // We're already at end so no need to seek this stream
+          remaining -= streamPos;
+          NS_ASSERTION(remaining >= 0, "Remaining invalid");
+        } else {
+          uint64_t avail;
+          rv = AvailableMaybeSeek(mStreams[i], &avail);
+          if (NS_WARN_IF(NS_FAILED(rv))) {
+            return rv;
+          }
+
+          int64_t newPos = XPCOM_MIN(remaining, streamPos + (int64_t)avail);
+
+          rv = stream->Seek(NS_SEEK_SET, newPos);
+          if (NS_WARN_IF(NS_FAILED(rv))) {
+            return rv;
+          }
+
+          mCurrentStream = i;
+          mStartedReadingCurrent = true;
+
+          remaining -= newPos;
+          NS_ASSERTION(remaining >= 0, "Remaining invalid");
+        }
+      } else {
+        NS_ASSERTION(remaining == streamPos, "Huh?");
+        remaining = 0;
+      }
+    }
+
+    return NS_OK;
+  }
+
+  if (aWhence == NS_SEEK_CUR && aOffset > 0) {
+    int64_t remaining = aOffset;
+    for (uint32_t i = mCurrentStream; remaining && i < mStreams.Length(); ++i) {
+      nsCOMPtr<nsISeekableStream> stream =
+        do_QueryInterface(mStreams[i]);
+
+      uint64_t avail;
+      rv = AvailableMaybeSeek(mStreams[i], &avail);
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        return rv;
+      }
+
+      int64_t seek = XPCOM_MIN((int64_t)avail, remaining);
+
+      rv = stream->Seek(NS_SEEK_CUR, seek);
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        return rv;
+      }
+
+      mCurrentStream = i;
+      mStartedReadingCurrent = true;
+
+      remaining -= seek;
+    }
+
+    return NS_OK;
+  }
+
+  if (aWhence == NS_SEEK_CUR && aOffset < 0) {
+    int64_t remaining = -aOffset;
+    for (uint32_t i = mCurrentStream; remaining && i != (uint32_t)-1; --i) {
+      nsCOMPtr<nsISeekableStream> stream =
+        do_QueryInterface(mStreams[i]);
+
+      int64_t pos;
+      rv = TellMaybeSeek(stream, &pos);
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        return rv;
+      }
+
+      int64_t seek = XPCOM_MIN(pos, remaining);
+
+      rv = stream->Seek(NS_SEEK_CUR, -seek);
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        return rv;
+      }
+
+      mCurrentStream = i;
+      mStartedReadingCurrent = seek != -pos;
+
+      remaining -= seek;
+    }
+
+    return NS_OK;
+  }
+
+  if (aWhence == NS_SEEK_CUR) {
+    NS_ASSERTION(aOffset == 0, "Should have handled all non-zero values");
+
+    return NS_OK;
+  }
+
+  if (aWhence == NS_SEEK_END) {
+    if (aOffset > 0) {
+      return NS_ERROR_INVALID_ARG;
+    }
+    int64_t remaining = aOffset;
+    for (uint32_t i = mStreams.Length() - 1; i != (uint32_t)-1; --i) {
+      nsCOMPtr<nsISeekableStream> stream =
+        do_QueryInterface(mStreams[i]);
+
+      // See if all remaining streams should be seeked to end
+      if (remaining == 0) {
+        if (i >= oldCurrentStream) {
+          rv = stream->Seek(NS_SEEK_END, 0);
+          if (NS_WARN_IF(NS_FAILED(rv))) {
+            return rv;
+          }
+        } else {
+          break;
+        }
+      }
+
+      // Get position in current stream
+      int64_t streamPos;
+      if (i < oldCurrentStream) {
+        streamPos = 0;
+      } else {
+        uint64_t avail;
+        rv = AvailableMaybeSeek(mStreams[i], &avail);
+        if (NS_WARN_IF(NS_FAILED(rv))) {
+          return rv;
+        }
+
+        streamPos = avail;
+      }
+
+      // See if we have enough data in the current stream.
+      if (DeprecatedAbs(remaining) < streamPos) {
+        rv = stream->Seek(NS_SEEK_END, remaining);
+        if (NS_WARN_IF(NS_FAILED(rv))) {
+          return rv;
+        }
+
+        mCurrentStream = i;
+        mStartedReadingCurrent = true;
+
+        remaining = 0;
+      } else if (DeprecatedAbs(remaining) > streamPos) {
+        if (i > oldCurrentStream ||
+            (i == oldCurrentStream && !oldStartedReadingCurrent)) {
+          // We're already at start so no need to seek this stream
+          remaining += streamPos;
+        } else {
+          int64_t avail;
+          rv = TellMaybeSeek(stream, &avail);
+          if (NS_WARN_IF(NS_FAILED(rv))) {
+            return rv;
+          }
+
+          int64_t newPos = streamPos + XPCOM_MIN(avail, DeprecatedAbs(remaining));
+
+          rv = stream->Seek(NS_SEEK_END, -newPos);
+          if (NS_WARN_IF(NS_FAILED(rv))) {
+            return rv;
+          }
+
+          mCurrentStream = i;
+          mStartedReadingCurrent = true;
+
+          remaining += newPos;
+        }
+      } else {
+        NS_ASSERTION(remaining == streamPos, "Huh?");
+        remaining = 0;
+      }
+    }
+
+    return NS_OK;
+  }
+
+  // other Seeks not implemented yet
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsMultiplexInputStream::Tell(int64_t* aResult)
+{
+  MutexAutoLock lock(mLock);
+
+  if (NS_FAILED(mStatus)) {
+    return mStatus;
+  }
+
+  nsresult rv;
+  int64_t ret64 = 0;
+  uint32_t i, last;
+  last = mStartedReadingCurrent ? mCurrentStream + 1 : mCurrentStream;
+  for (i = 0; i < last; ++i) {
+    nsCOMPtr<nsISeekableStream> stream = do_QueryInterface(mStreams[i]);
+    if (NS_WARN_IF(!stream)) {
+      return NS_ERROR_NO_INTERFACE;
+    }
+
+    int64_t pos;
+    rv = TellMaybeSeek(stream, &pos);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+    ret64 += pos;
+  }
+  *aResult =  ret64;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMultiplexInputStream::SetEOF()
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+nsresult
+nsMultiplexInputStreamConstructor(nsISupports* aOuter,
+                                  REFNSIID aIID,
+                                  void** aResult)
+{
+  *aResult = nullptr;
+
+  if (aOuter) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+
+  RefPtr<nsMultiplexInputStream> inst = new nsMultiplexInputStream();
+
+  return inst->QueryInterface(aIID, aResult);
+}
+
+void
+nsMultiplexInputStream::Serialize(InputStreamParams& aParams,
+                                  FileDescriptorArray& aFileDescriptors)
+{
+  MutexAutoLock lock(mLock);
+
+  MultiplexInputStreamParams params;
+
+  uint32_t streamCount = mStreams.Length();
+
+  if (streamCount) {
+    InfallibleTArray<InputStreamParams>& streams = params.streams();
+
+    streams.SetCapacity(streamCount);
+    for (uint32_t index = 0; index < streamCount; index++) {
+      InputStreamParams childStreamParams;
+      SerializeInputStream(mStreams[index], childStreamParams,
+                           aFileDescriptors);
+
+      streams.AppendElement(childStreamParams);
+    }
+  }
+
+  params.currentStream() = mCurrentStream;
+  params.status() = mStatus;
+  params.startedReadingCurrent() = mStartedReadingCurrent;
+
+  aParams = params;
+}
+
+bool
+nsMultiplexInputStream::Deserialize(const InputStreamParams& aParams,
+                                    const FileDescriptorArray& aFileDescriptors)
+{
+  if (aParams.type() !=
+      InputStreamParams::TMultiplexInputStreamParams) {
+    NS_ERROR("Received unknown parameters from the other process!");
+    return false;
+  }
+
+  const MultiplexInputStreamParams& params =
+    aParams.get_MultiplexInputStreamParams();
+
+  const InfallibleTArray<InputStreamParams>& streams = params.streams();
+
+  uint32_t streamCount = streams.Length();
+  for (uint32_t index = 0; index < streamCount; index++) {
+    nsCOMPtr<nsIInputStream> stream =
+      DeserializeInputStream(streams[index], aFileDescriptors);
+    if (!stream) {
+      NS_WARNING("Deserialize failed!");
+      return false;
+    }
+
+    if (NS_FAILED(AppendStream(stream))) {
+      NS_WARNING("AppendStream failed!");
+      return false;
+    }
+  }
+
+  mCurrentStream = params.currentStream();
+  mStatus = params.status();
+  mStartedReadingCurrent = params.startedReadingCurrent();
+
+  return true;
+}
+
+Maybe<uint64_t>
+nsMultiplexInputStream::ExpectedSerializedLength()
+{
+  MutexAutoLock lock(mLock);
+
+  bool lengthValueExists = false;
+  uint64_t expectedLength = 0;
+  uint32_t streamCount = mStreams.Length();
+  for (uint32_t index = 0; index < streamCount; index++) {
+    nsCOMPtr<nsIIPCSerializableInputStream> stream = do_QueryInterface(mStreams[index]);
+    if (!stream) {
+      continue;
+    }
+    Maybe<uint64_t> length = stream->ExpectedSerializedLength();
+    if (length.isNothing()) {
+      continue;
+    }
+    lengthValueExists = true;
+    expectedLength += length.value();
+  }
+  return lengthValueExists ? Some(expectedLength) : Nothing();
+}
+
+NS_IMETHODIMP
+nsMultiplexInputStream::GetCloneable(bool* aCloneable)
+{
+  MutexAutoLock lock(mLock);
+  //XXXnsm Cloning a multiplex stream which has started reading is not permitted
+  //right now.
+  if (mCurrentStream > 0 || mStartedReadingCurrent) {
+    *aCloneable = false;
+    return NS_OK;
+  }
+
+  uint32_t len = mStreams.Length();
+  for (uint32_t i = 0; i < len; ++i) {
+    nsCOMPtr<nsICloneableInputStream> cis = do_QueryInterface(mStreams[i]);
+    if (!cis || !cis->GetCloneable()) {
+      *aCloneable = false;
+      return NS_OK;
+    }
+  }
+
+  *aCloneable = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMultiplexInputStream::Clone(nsIInputStream** aClone)
+{
+  MutexAutoLock lock(mLock);
+
+  //XXXnsm Cloning a multiplex stream which has started reading is not permitted
+  //right now.
+  if (mCurrentStream > 0 || mStartedReadingCurrent) {
+    return NS_ERROR_FAILURE;
+  }
+
+  RefPtr<nsMultiplexInputStream> clone = new nsMultiplexInputStream();
+
+  nsresult rv;
+  uint32_t len = mStreams.Length();
+  for (uint32_t i = 0; i < len; ++i) {
+    nsCOMPtr<nsICloneableInputStream> substream = do_QueryInterface(mStreams[i]);
+    if (NS_WARN_IF(!substream)) {
+      return NS_ERROR_FAILURE;
+    }
+
+    nsCOMPtr<nsIInputStream> clonedSubstream;
+    rv = substream->Clone(getter_AddRefs(clonedSubstream));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    rv = clone->AppendStream(clonedSubstream);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+  clone.forget(aClone);
+  return NS_OK;
+}
diff --git a/xpcom/io/nsMultiplexInputStream.h b/xpcom/io/nsMultiplexInputStream.h
new file mode 100644
index 000000000..381051dca
--- /dev/null
+++ b/xpcom/io/nsMultiplexInputStream.h
@@ -0,0 +1,30 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * The multiplex stream concatenates a list of input streams into a single
+ * stream.
+ */
+
+#ifndef _nsMultiplexInputStream_h_
+#define _nsMultiplexInputStream_h_
+
+#include "nsIMultiplexInputStream.h"
+
+#define NS_MULTIPLEXINPUTSTREAM_CONTRACTID "@mozilla.org/io/multiplex-input-stream;1"
+#define NS_MULTIPLEXINPUTSTREAM_CID                  \
+  { /* 565e3a2c-1dd2-11b2-8da1-b4cef17e568d */       \
+    0x565e3a2c,                                      \
+    0x1dd2,                                          \
+    0x11b2,                                          \
+    {0x8d, 0xa1, 0xb4, 0xce, 0xf1, 0x7e, 0x56, 0x8d} \
+  }
+
+extern nsresult nsMultiplexInputStreamConstructor(nsISupports* aOuter,
+                                                  REFNSIID aIID,
+                                                  void** aResult);
+
+#endif //  _nsMultiplexInputStream_h_
diff --git a/xpcom/io/nsNativeCharsetUtils.cpp b/xpcom/io/nsNativeCharsetUtils.cpp
new file mode 100644
index 000000000..e53307af5
--- /dev/null
+++ b/xpcom/io/nsNativeCharsetUtils.cpp
@@ -0,0 +1,1044 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "xpcom-private.h"
+
+//-----------------------------------------------------------------------------
+// XP_MACOSX or ANDROID
+//-----------------------------------------------------------------------------
+#if defined(XP_MACOSX) || defined(ANDROID)
+
+#include "nsAString.h"
+#include "nsReadableUtils.h"
+#include "nsString.h"
+
+nsresult
+NS_CopyNativeToUnicode(const nsACString& aInput, nsAString& aOutput)
+{
+  CopyUTF8toUTF16(aInput, aOutput);
+  return NS_OK;
+}
+
+nsresult
+NS_CopyUnicodeToNative(const nsAString&  aInput, nsACString& aOutput)
+{
+  CopyUTF16toUTF8(aInput, aOutput);
+  return NS_OK;
+}
+
+void
+NS_StartupNativeCharsetUtils()
+{
+}
+
+void
+NS_ShutdownNativeCharsetUtils()
+{
+}
+
+
+//-----------------------------------------------------------------------------
+// XP_UNIX
+//-----------------------------------------------------------------------------
+#elif defined(XP_UNIX)
+
+#include <stdlib.h>   // mbtowc, wctomb
+#include <locale.h>   // setlocale
+#include "mozilla/Mutex.h"
+#include "nscore.h"
+#include "nsAString.h"
+#include "nsReadableUtils.h"
+
+using namespace mozilla;
+
+//
+// choose a conversion library.  we used to use mbrtowc/wcrtomb under Linux,
+// but that doesn't work for non-BMP characters whether we use '-fshort-wchar'
+// or not (see bug 206811 and
+// news://news.mozilla.org:119/bajml3$fvr1@ripley.netscape.com). we now use
+// iconv for all platforms where nltypes.h and nllanginfo.h are present
+// along with iconv.
+//
+#if defined(HAVE_ICONV) && defined(HAVE_NL_TYPES_H) && defined(HAVE_LANGINFO_CODESET)
+#define USE_ICONV 1
+#else
+#define USE_STDCONV 1
+#endif
+
+static void
+isolatin1_to_utf16(const char** aInput, uint32_t* aInputLeft,
+                   char16_t** aOutput, uint32_t* aOutputLeft)
+{
+  while (*aInputLeft && *aOutputLeft) {
+    **aOutput = (unsigned char)** aInput;
+    (*aInput)++;
+    (*aInputLeft)--;
+    (*aOutput)++;
+    (*aOutputLeft)--;
+  }
+}
+
+static void
+utf16_to_isolatin1(const char16_t** aInput, uint32_t* aInputLeft,
+                   char** aOutput, uint32_t* aOutputLeft)
+{
+  while (*aInputLeft && *aOutputLeft) {
+    **aOutput = (unsigned char)**aInput;
+    (*aInput)++;
+    (*aInputLeft)--;
+    (*aOutput)++;
+    (*aOutputLeft)--;
+  }
+}
+
+//-----------------------------------------------------------------------------
+// conversion using iconv
+//-----------------------------------------------------------------------------
+#if defined(USE_ICONV)
+#include <nl_types.h> // CODESET
+#include <langinfo.h> // nl_langinfo
+#include <iconv.h>    // iconv_open, iconv, iconv_close
+#include <errno.h>
+#include "plstr.h"
+
+#if defined(HAVE_ICONV_WITH_CONST_INPUT)
+#define ICONV_INPUT(x) (x)
+#else
+#define ICONV_INPUT(x) ((char **)x)
+#endif
+
+// solaris definitely needs this, but we'll enable it by default
+// just in case... but we know for sure that iconv(3) in glibc
+// doesn't need this.
+#if !defined(__GLIBC__)
+#define ENABLE_UTF8_FALLBACK_SUPPORT
+#endif
+
+#define INVALID_ICONV_T ((iconv_t)-1)
+
+static inline size_t
+xp_iconv(iconv_t converter,
+         const char** aInput, size_t* aInputLeft,
+         char** aOutput, size_t* aOutputLeft)
+{
+  size_t res, outputAvail = *aOutputLeft;
+  res = iconv(converter, ICONV_INPUT(aInput), aInputLeft, aOutput, aOutputLeft);
+  if (res == (size_t)-1) {
+    // on some platforms (e.g., linux) iconv will fail with
+    // E2BIG if it cannot convert _all_ of its input.  it'll
+    // still adjust all of the in/out params correctly, so we
+    // can ignore this error.  the assumption is that we will
+    // be called again to complete the conversion.
+    if ((errno == E2BIG) && (*aOutputLeft < outputAvail)) {
+      res = 0;
+    }
+  }
+  return res;
+}
+
+static inline void
+xp_iconv_reset(iconv_t converter)
+{
+  // NOTE: the man pages on Solaris claim that you can pass nullptr
+  // for all parameter to reset the converter, but beware the
+  // evil Solaris crash if you go down this route >:-)
+
+  const char* zero_char_in_ptr  = nullptr;
+  char* zero_char_out_ptr = nullptr;
+  size_t zero_size_in = 0;
+  size_t zero_size_out = 0;
+
+  xp_iconv(converter,
+           &zero_char_in_ptr,
+           &zero_size_in,
+           &zero_char_out_ptr,
+           &zero_size_out);
+}
+
+static inline iconv_t
+xp_iconv_open(const char** to_list, const char** from_list)
+{
+  iconv_t res;
+  const char** from_name;
+  const char** to_name;
+
+  // try all possible combinations to locate a converter.
+  to_name = to_list;
+  while (*to_name) {
+    if (**to_name) {
+      from_name = from_list;
+      while (*from_name) {
+        if (**from_name) {
+          res = iconv_open(*to_name, *from_name);
+          if (res != INVALID_ICONV_T) {
+            return res;
+          }
+        }
+        from_name++;
+      }
+    }
+    to_name++;
+  }
+
+  return INVALID_ICONV_T;
+}
+
+/*
+ * char16_t[] is NOT a UCS-2 array BUT a UTF-16 string. Therefore, we
+ * have to use UTF-16 with iconv(3) on platforms where it's supported.
+ * However, the way UTF-16 and UCS-2 are interpreted varies across platforms
+ * and implementations of iconv(3). On Tru64, it also depends on the environment
+ * variable. To avoid the trouble arising from byte-swapping
+ * (bug 208809), we have to try UTF-16LE/BE and UCS-2LE/BE before falling
+ * back to UTF-16 and UCS-2 and variants. We assume that UTF-16 and UCS-2
+ * on systems without UTF-16LE/BE and UCS-2LE/BE have the native endianness,
+ * which isn't the case of glibc 2.1.x, for which we use 'UNICODELITTLE'
+ * and 'UNICODEBIG'. It's also not true of Tru64 V4 when the environment
+ * variable ICONV_BYTEORDER is set to 'big-endian', about which not much
+ * can be done other than adding a note in the release notes. (bug 206811)
+ */
+static const char* UTF_16_NAMES[] = {
+#if defined(IS_LITTLE_ENDIAN)
+  "UTF-16LE",
+#if defined(__GLIBC__)
+  "UNICODELITTLE",
+#endif
+  "UCS-2LE",
+#else
+  "UTF-16BE",
+#if defined(__GLIBC__)
+  "UNICODEBIG",
+#endif
+  "UCS-2BE",
+#endif
+  "UTF-16",
+  "UCS-2",
+  "UCS2",
+  "UCS_2",
+  "ucs-2",
+  "ucs2",
+  "ucs_2",
+  nullptr
+};
+
+#if defined(ENABLE_UTF8_FALLBACK_SUPPORT)
+static const char* UTF_8_NAMES[] = {
+  "UTF-8",
+  "UTF8",
+  "UTF_8",
+  "utf-8",
+  "utf8",
+  "utf_8",
+  nullptr
+};
+#endif
+
+static const char* ISO_8859_1_NAMES[] = {
+  "ISO-8859-1",
+#if !defined(__GLIBC__)
+  "ISO8859-1",
+  "ISO88591",
+  "ISO_8859_1",
+  "ISO8859_1",
+  "iso-8859-1",
+  "iso8859-1",
+  "iso88591",
+  "iso_8859_1",
+  "iso8859_1",
+#endif
+  nullptr
+};
+
+class nsNativeCharsetConverter
+{
+public:
+  nsNativeCharsetConverter();
+  ~nsNativeCharsetConverter();
+
+  nsresult NativeToUnicode(const char** aInput, uint32_t* aInputLeft,
+                           char16_t** aOutput, uint32_t* aOutputLeft);
+  nsresult UnicodeToNative(const char16_t** aInput, uint32_t* aInputLeft,
+                           char** aOutput, uint32_t* aOutputLeft);
+
+  static void GlobalInit();
+  static void GlobalShutdown();
+  static bool IsNativeUTF8();
+
+private:
+  static iconv_t gNativeToUnicode;
+  static iconv_t gUnicodeToNative;
+#if defined(ENABLE_UTF8_FALLBACK_SUPPORT)
+  static iconv_t gNativeToUTF8;
+  static iconv_t gUTF8ToNative;
+  static iconv_t gUnicodeToUTF8;
+  static iconv_t gUTF8ToUnicode;
+#endif
+  static Mutex*  gLock;
+  static bool    gInitialized;
+  static bool    gIsNativeUTF8;
+
+  static void LazyInit();
+
+  static void Lock()
+  {
+    if (gLock) {
+      gLock->Lock();
+    }
+  }
+  static void Unlock()
+  {
+    if (gLock) {
+      gLock->Unlock();
+    }
+  }
+};
+
+iconv_t nsNativeCharsetConverter::gNativeToUnicode = INVALID_ICONV_T;
+iconv_t nsNativeCharsetConverter::gUnicodeToNative = INVALID_ICONV_T;
+#if defined(ENABLE_UTF8_FALLBACK_SUPPORT)
+iconv_t nsNativeCharsetConverter::gNativeToUTF8    = INVALID_ICONV_T;
+iconv_t nsNativeCharsetConverter::gUTF8ToNative    = INVALID_ICONV_T;
+iconv_t nsNativeCharsetConverter::gUnicodeToUTF8   = INVALID_ICONV_T;
+iconv_t nsNativeCharsetConverter::gUTF8ToUnicode   = INVALID_ICONV_T;
+#endif
+Mutex*  nsNativeCharsetConverter::gLock            = nullptr;
+bool    nsNativeCharsetConverter::gInitialized     = false;
+bool    nsNativeCharsetConverter::gIsNativeUTF8    = false;
+
+void
+nsNativeCharsetConverter::LazyInit()
+{
+  // LazyInit may be called before NS_StartupNativeCharsetUtils, but
+  // the setlocale it does has to be called before nl_langinfo. Like in
+  // NS_StartupNativeCharsetUtils, assume we are called early enough that
+  // we are the first to care about the locale's charset.
+  if (!gLock) {
+    setlocale(LC_CTYPE, "");
+  }
+  const char* blank_list[] = { "", nullptr };
+  const char** native_charset_list = blank_list;
+  const char* native_charset = nl_langinfo(CODESET);
+  if (!native_charset) {
+    NS_ERROR("native charset is unknown");
+    // fallback to ISO-8859-1
+    native_charset_list = ISO_8859_1_NAMES;
+  } else {
+    native_charset_list[0] = native_charset;
+  }
+
+  // Most, if not all, Unixen supporting UTF-8 and nl_langinfo(CODESET)
+  // return 'UTF-8' (or 'utf-8')
+  if (!PL_strcasecmp(native_charset, "UTF-8")) {
+    gIsNativeUTF8 = true;
+  }
+
+  gNativeToUnicode = xp_iconv_open(UTF_16_NAMES, native_charset_list);
+  gUnicodeToNative = xp_iconv_open(native_charset_list, UTF_16_NAMES);
+
+#if defined(ENABLE_UTF8_FALLBACK_SUPPORT)
+  if (gNativeToUnicode == INVALID_ICONV_T) {
+    gNativeToUTF8 = xp_iconv_open(UTF_8_NAMES, native_charset_list);
+    gUTF8ToUnicode = xp_iconv_open(UTF_16_NAMES, UTF_8_NAMES);
+    NS_ASSERTION(gNativeToUTF8 != INVALID_ICONV_T, "no native to utf-8 converter");
+    NS_ASSERTION(gUTF8ToUnicode != INVALID_ICONV_T, "no utf-8 to utf-16 converter");
+  }
+  if (gUnicodeToNative == INVALID_ICONV_T) {
+    gUnicodeToUTF8 = xp_iconv_open(UTF_8_NAMES, UTF_16_NAMES);
+    gUTF8ToNative = xp_iconv_open(native_charset_list, UTF_8_NAMES);
+    NS_ASSERTION(gUnicodeToUTF8 != INVALID_ICONV_T, "no utf-16 to utf-8 converter");
+    NS_ASSERTION(gUTF8ToNative != INVALID_ICONV_T, "no utf-8 to native converter");
+  }
+#else
+  NS_ASSERTION(gNativeToUnicode != INVALID_ICONV_T, "no native to utf-16 converter");
+  NS_ASSERTION(gUnicodeToNative != INVALID_ICONV_T, "no utf-16 to native converter");
+#endif
+
+  /*
+   * On Solaris 8 (and newer?), the iconv modules converting to UCS-2
+   * prepend a byte order mark unicode character (BOM, u+FEFF) during
+   * the first use of the iconv converter. The same is the case of
+   * glibc 2.2.9x and Tru64 V5 (see bug 208809) when 'UTF-16' is used.
+   * However, we use 'UTF-16LE/BE' in both cases, instead so that we
+   * should be safe. But just in case...
+   *
+   * This dummy conversion gets rid of the BOMs and fixes bug 153562.
+   */
+  char dummy_input[1] = { ' ' };
+  char dummy_output[4];
+
+  if (gNativeToUnicode != INVALID_ICONV_T) {
+    const char* input = dummy_input;
+    size_t input_left = sizeof(dummy_input);
+    char* output = dummy_output;
+    size_t output_left = sizeof(dummy_output);
+
+    xp_iconv(gNativeToUnicode, &input, &input_left, &output, &output_left);
+  }
+#if defined(ENABLE_UTF8_FALLBACK_SUPPORT)
+  if (gUTF8ToUnicode != INVALID_ICONV_T) {
+    const char* input = dummy_input;
+    size_t input_left = sizeof(dummy_input);
+    char* output = dummy_output;
+    size_t output_left = sizeof(dummy_output);
+
+    xp_iconv(gUTF8ToUnicode, &input, &input_left, &output, &output_left);
+  }
+#endif
+
+  gInitialized = true;
+}
+
+void
+nsNativeCharsetConverter::GlobalInit()
+{
+  gLock = new Mutex("nsNativeCharsetConverter.gLock");
+}
+
+void
+nsNativeCharsetConverter::GlobalShutdown()
+{
+  delete gLock;
+  gLock = nullptr;
+
+  if (gNativeToUnicode != INVALID_ICONV_T) {
+    iconv_close(gNativeToUnicode);
+    gNativeToUnicode = INVALID_ICONV_T;
+  }
+
+  if (gUnicodeToNative != INVALID_ICONV_T) {
+    iconv_close(gUnicodeToNative);
+    gUnicodeToNative = INVALID_ICONV_T;
+  }
+
+#if defined(ENABLE_UTF8_FALLBACK_SUPPORT)
+  if (gNativeToUTF8 != INVALID_ICONV_T) {
+    iconv_close(gNativeToUTF8);
+    gNativeToUTF8 = INVALID_ICONV_T;
+  }
+  if (gUTF8ToNative != INVALID_ICONV_T) {
+    iconv_close(gUTF8ToNative);
+    gUTF8ToNative = INVALID_ICONV_T;
+  }
+  if (gUnicodeToUTF8 != INVALID_ICONV_T) {
+    iconv_close(gUnicodeToUTF8);
+    gUnicodeToUTF8 = INVALID_ICONV_T;
+  }
+  if (gUTF8ToUnicode != INVALID_ICONV_T) {
+    iconv_close(gUTF8ToUnicode);
+    gUTF8ToUnicode = INVALID_ICONV_T;
+  }
+#endif
+
+  gInitialized = false;
+}
+
+nsNativeCharsetConverter::nsNativeCharsetConverter()
+{
+  Lock();
+  if (!gInitialized) {
+    LazyInit();
+  }
+}
+
+nsNativeCharsetConverter::~nsNativeCharsetConverter()
+{
+  // reset converters for next time
+  if (gNativeToUnicode != INVALID_ICONV_T) {
+    xp_iconv_reset(gNativeToUnicode);
+  }
+  if (gUnicodeToNative != INVALID_ICONV_T) {
+    xp_iconv_reset(gUnicodeToNative);
+  }
+#if defined(ENABLE_UTF8_FALLBACK_SUPPORT)
+  if (gNativeToUTF8 != INVALID_ICONV_T) {
+    xp_iconv_reset(gNativeToUTF8);
+  }
+  if (gUTF8ToNative != INVALID_ICONV_T) {
+    xp_iconv_reset(gUTF8ToNative);
+  }
+  if (gUnicodeToUTF8 != INVALID_ICONV_T) {
+    xp_iconv_reset(gUnicodeToUTF8);
+  }
+  if (gUTF8ToUnicode != INVALID_ICONV_T) {
+    xp_iconv_reset(gUTF8ToUnicode);
+  }
+#endif
+  Unlock();
+}
+
+nsresult
+nsNativeCharsetConverter::NativeToUnicode(const char** aInput,
+                                          uint32_t* aInputLeft,
+                                          char16_t** aOutput,
+                                          uint32_t* aOutputLeft)
+{
+  size_t res = 0;
+  size_t inLeft = (size_t)*aInputLeft;
+  size_t outLeft = (size_t)*aOutputLeft * 2;
+
+  if (gNativeToUnicode != INVALID_ICONV_T) {
+
+    res = xp_iconv(gNativeToUnicode, aInput, &inLeft, (char**)aOutput, &outLeft);
+
+    *aInputLeft = inLeft;
+    *aOutputLeft = outLeft / 2;
+    if (res != (size_t)-1) {
+      return NS_OK;
+    }
+
+    NS_WARNING("conversion from native to utf-16 failed");
+
+    // reset converter
+    xp_iconv_reset(gNativeToUnicode);
+  }
+#if defined(ENABLE_UTF8_FALLBACK_SUPPORT)
+  else if ((gNativeToUTF8 != INVALID_ICONV_T) &&
+           (gUTF8ToUnicode != INVALID_ICONV_T)) {
+    // convert first to UTF8, then from UTF8 to UCS2
+    const char* in = *aInput;
+
+    char ubuf[1024];
+
+    // we assume we're always called with enough space in |aOutput|,
+    // so convert many chars at a time...
+    while (inLeft) {
+      char* p = ubuf;
+      size_t n = sizeof(ubuf);
+      res = xp_iconv(gNativeToUTF8, &in, &inLeft, &p, &n);
+      if (res == (size_t)-1) {
+        NS_ERROR("conversion from native to utf-8 failed");
+        break;
+      }
+      NS_ASSERTION(outLeft > 0, "bad assumption");
+      p = ubuf;
+      n = sizeof(ubuf) - n;
+      res = xp_iconv(gUTF8ToUnicode, (const char**)&p, &n,
+                     (char**)aOutput, &outLeft);
+      if (res == (size_t)-1) {
+        NS_ERROR("conversion from utf-8 to utf-16 failed");
+        break;
+      }
+    }
+
+    (*aInput) += (*aInputLeft - inLeft);
+    *aInputLeft = inLeft;
+    *aOutputLeft = outLeft / 2;
+
+    if (res != (size_t)-1) {
+      return NS_OK;
+    }
+
+    // reset converters
+    xp_iconv_reset(gNativeToUTF8);
+    xp_iconv_reset(gUTF8ToUnicode);
+  }
+#endif
+
+  // fallback: zero-pad and hope for the best
+  // XXX This is lame and we have to do better.
+  isolatin1_to_utf16(aInput, aInputLeft, aOutput, aOutputLeft);
+
+  return NS_OK;
+}
+
+nsresult
+nsNativeCharsetConverter::UnicodeToNative(const char16_t** aInput,
+                                          uint32_t* aInputLeft,
+                                          char** aOutput,
+                                          uint32_t* aOutputLeft)
+{
+  size_t res = 0;
+  size_t inLeft = (size_t)*aInputLeft * 2;
+  size_t outLeft = (size_t)*aOutputLeft;
+
+  if (gUnicodeToNative != INVALID_ICONV_T) {
+    res = xp_iconv(gUnicodeToNative, (const char**)aInput, &inLeft,
+                   aOutput, &outLeft);
+
+    *aInputLeft = inLeft / 2;
+    *aOutputLeft = outLeft;
+    if (res != (size_t)-1) {
+      return NS_OK;
+    }
+
+    NS_ERROR("iconv failed");
+
+    // reset converter
+    xp_iconv_reset(gUnicodeToNative);
+  }
+#if defined(ENABLE_UTF8_FALLBACK_SUPPORT)
+  else if ((gUnicodeToUTF8 != INVALID_ICONV_T) &&
+           (gUTF8ToNative != INVALID_ICONV_T)) {
+    const char* in = (const char*)*aInput;
+
+    char ubuf[6]; // max utf-8 char length (really only needs to be 4 bytes)
+
+    // convert one uchar at a time...
+    while (inLeft && outLeft) {
+      char* p = ubuf;
+      size_t n = sizeof(ubuf), one_uchar = sizeof(char16_t);
+      res = xp_iconv(gUnicodeToUTF8, &in, &one_uchar, &p, &n);
+      if (res == (size_t)-1) {
+        NS_ERROR("conversion from utf-16 to utf-8 failed");
+        break;
+      }
+      p = ubuf;
+      n = sizeof(ubuf) - n;
+      res = xp_iconv(gUTF8ToNative, (const char**)&p, &n, aOutput, &outLeft);
+      if (res == (size_t)-1) {
+        if (errno == E2BIG) {
+          // not enough room for last uchar... back up and return.
+          in -= sizeof(char16_t);
+          res = 0;
+        } else {
+          NS_ERROR("conversion from utf-8 to native failed");
+        }
+        break;
+      }
+      inLeft -= sizeof(char16_t);
+    }
+
+    (*aInput) += (*aInputLeft - inLeft / 2);
+    *aInputLeft = inLeft / 2;
+    *aOutputLeft = outLeft;
+    if (res != (size_t)-1) {
+      return NS_OK;
+    }
+
+    // reset converters
+    xp_iconv_reset(gUnicodeToUTF8);
+    xp_iconv_reset(gUTF8ToNative);
+  }
+#endif
+
+  // fallback: truncate and hope for the best
+  // XXX This is lame and we have to do better.
+  utf16_to_isolatin1(aInput, aInputLeft, aOutput, aOutputLeft);
+
+  return NS_OK;
+}
+
+bool
+nsNativeCharsetConverter::IsNativeUTF8()
+{
+  if (!gInitialized) {
+    Lock();
+    if (!gInitialized) {
+      LazyInit();
+    }
+    Unlock();
+  }
+  return gIsNativeUTF8;
+}
+
+#endif // USE_ICONV
+
+//-----------------------------------------------------------------------------
+// conversion using mb[r]towc/wc[r]tomb
+//-----------------------------------------------------------------------------
+#if defined(USE_STDCONV)
+#if defined(HAVE_WCRTOMB) || defined(HAVE_MBRTOWC)
+#include <wchar.h>    // mbrtowc, wcrtomb
+#endif
+
+class nsNativeCharsetConverter
+{
+public:
+  nsNativeCharsetConverter();
+
+  nsresult NativeToUnicode(const char** aInput, uint32_t* aInputLeft,
+                           char16_t** aOutput, uint32_t* aOutputLeft);
+  nsresult UnicodeToNative(const char16_t** aInput, uint32_t* aInputLeft,
+                           char** aOutput, uint32_t* aOutputLeft);
+
+  static void GlobalInit();
+  static void GlobalShutdown() { }
+  static bool IsNativeUTF8();
+
+private:
+  static bool gWCharIsUnicode;
+
+#if defined(HAVE_WCRTOMB) || defined(HAVE_MBRTOWC)
+  mbstate_t ps;
+#endif
+};
+
+bool nsNativeCharsetConverter::gWCharIsUnicode = false;
+
+nsNativeCharsetConverter::nsNativeCharsetConverter()
+{
+#if defined(HAVE_WCRTOMB) || defined(HAVE_MBRTOWC)
+  memset(&ps, 0, sizeof(ps));
+#endif
+}
+
+void
+nsNativeCharsetConverter::GlobalInit()
+{
+  // verify that wchar_t for the current locale is actually unicode.
+  // if it is not, then we should avoid calling mbtowc/wctomb and
+  // just fallback on zero-pad/truncation conversion.
+  //
+  // this test cannot be done at build time because the encoding of
+  // wchar_t may depend on the runtime locale.  sad, but true!!
+  //
+  // so, if wchar_t is unicode then converting an ASCII character
+  // to wchar_t should not change its numeric value.  we'll just
+  // check what happens with the ASCII 'a' character.
+  //
+  // this test is not perfect... obviously, it could yield false
+  // positives, but then at least ASCII text would be converted
+  // properly (or maybe just the 'a' character) -- oh well :(
+
+  char a = 'a';
+  unsigned int w = 0;
+
+  int res = mbtowc((wchar_t*)&w, &a, 1);
+
+  gWCharIsUnicode = (res != -1 && w == 'a');
+
+#ifdef DEBUG
+  if (!gWCharIsUnicode) {
+    NS_WARNING("wchar_t is not unicode (unicode conversion will be lossy)");
+  }
+#endif
+}
+
+nsresult
+nsNativeCharsetConverter::NativeToUnicode(const char** aInput,
+                                          uint32_t* aInputLeft,
+                                          char16_t** aOutput,
+                                          uint32_t* aOutputLeft)
+{
+  if (gWCharIsUnicode) {
+    int incr;
+
+    // cannot use wchar_t here since it may have been redefined (e.g.,
+    // via -fshort-wchar).  hopefully, sizeof(tmp) is sufficient XP.
+    unsigned int tmp = 0;
+    while (*aInputLeft && *aOutputLeft) {
+#ifdef HAVE_MBRTOWC
+      incr = (int)mbrtowc((wchar_t*)&tmp, *aInput, *aInputLeft, &ps);
+#else
+      // XXX is this thread-safe?
+      incr = (int)mbtowc((wchar_t*)&tmp, *aInput, *aInputLeft);
+#endif
+      if (incr < 0) {
+        NS_WARNING("mbtowc failed: possible charset mismatch");
+        // zero-pad and hope for the best
+        tmp = (unsigned char)**aInput;
+        incr = 1;
+      }
+      ** aOutput = (char16_t)tmp;
+      (*aInput) += incr;
+      (*aInputLeft) -= incr;
+      (*aOutput)++;
+      (*aOutputLeft)--;
+    }
+  } else {
+    // wchar_t isn't unicode, so the best we can do is treat the
+    // input as if it is isolatin1 :(
+    isolatin1_to_utf16(aInput, aInputLeft, aOutput, aOutputLeft);
+  }
+
+  return NS_OK;
+}
+
+nsresult
+nsNativeCharsetConverter::UnicodeToNative(const char16_t** aInput,
+                                          uint32_t* aInputLeft,
+                                          char** aOutput,
+                                          uint32_t* aOutputLeft)
+{
+  if (gWCharIsUnicode) {
+    int incr;
+
+    while (*aInputLeft && *aOutputLeft >= MB_CUR_MAX) {
+#ifdef HAVE_WCRTOMB
+      incr = (int)wcrtomb(*aOutput, (wchar_t)**aInput, &ps);
+#else
+      // XXX is this thread-safe?
+      incr = (int)wctomb(*aOutput, (wchar_t)**aInput);
+#endif
+      if (incr < 0) {
+        NS_WARNING("mbtowc failed: possible charset mismatch");
+        ** aOutput = (unsigned char)**aInput; // truncate
+        incr = 1;
+      }
+      // most likely we're dead anyways if this assertion should fire
+      NS_ASSERTION(uint32_t(incr) <= *aOutputLeft, "wrote beyond end of string");
+      (*aOutput) += incr;
+      (*aOutputLeft) -= incr;
+      (*aInput)++;
+      (*aInputLeft)--;
+    }
+  } else {
+    // wchar_t isn't unicode, so the best we can do is treat the
+    // input as if it is isolatin1 :(
+    utf16_to_isolatin1(aInput, aInputLeft, aOutput, aOutputLeft);
+  }
+
+  return NS_OK;
+}
+
+// XXX : for now, return false
+bool
+nsNativeCharsetConverter::IsNativeUTF8()
+{
+  return false;
+}
+
+#endif // USE_STDCONV
+
+//-----------------------------------------------------------------------------
+// API implementation
+//-----------------------------------------------------------------------------
+
+nsresult
+NS_CopyNativeToUnicode(const nsACString& aInput, nsAString& aOutput)
+{
+  aOutput.Truncate();
+
+  uint32_t inputLen = aInput.Length();
+
+  nsACString::const_iterator iter;
+  aInput.BeginReading(iter);
+
+  //
+  // OPTIMIZATION: preallocate space for largest possible result; convert
+  // directly into the result buffer to avoid intermediate buffer copy.
+  //
+  // this will generally result in a larger allocation, but that seems
+  // better than an extra buffer copy.
+  //
+  if (!aOutput.SetLength(inputLen, fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  nsAString::iterator out_iter;
+  aOutput.BeginWriting(out_iter);
+
+  char16_t* result = out_iter.get();
+  uint32_t resultLeft = inputLen;
+
+  const char* buf = iter.get();
+  uint32_t bufLeft = inputLen;
+
+  nsNativeCharsetConverter conv;
+  nsresult rv = conv.NativeToUnicode(&buf, &bufLeft, &result, &resultLeft);
+  if (NS_SUCCEEDED(rv)) {
+    NS_ASSERTION(bufLeft == 0, "did not consume entire input buffer");
+    aOutput.SetLength(inputLen - resultLeft);
+  }
+  return rv;
+}
+
+nsresult
+NS_CopyUnicodeToNative(const nsAString& aInput, nsACString& aOutput)
+{
+  aOutput.Truncate();
+
+  nsAString::const_iterator iter, end;
+  aInput.BeginReading(iter);
+  aInput.EndReading(end);
+
+  // cannot easily avoid intermediate buffer copy.
+  char temp[4096];
+
+  nsNativeCharsetConverter conv;
+
+  const char16_t* buf = iter.get();
+  uint32_t bufLeft = Distance(iter, end);
+  while (bufLeft) {
+    char* p = temp;
+    uint32_t tempLeft = sizeof(temp);
+
+    nsresult rv = conv.UnicodeToNative(&buf, &bufLeft, &p, &tempLeft);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    if (tempLeft < sizeof(temp)) {
+      aOutput.Append(temp, sizeof(temp) - tempLeft);
+    }
+  }
+  return NS_OK;
+}
+
+bool
+NS_IsNativeUTF8()
+{
+  return nsNativeCharsetConverter::IsNativeUTF8();
+}
+
+void
+NS_StartupNativeCharsetUtils()
+{
+  //
+  // need to initialize the locale or else charset conversion will fail.
+  // better not delay this in case some other component alters the locale
+  // settings.
+  //
+  // XXX we assume that we are called early enough that we should
+  // always be the first to care about the locale's charset.
+  //
+  setlocale(LC_CTYPE, "");
+
+  nsNativeCharsetConverter::GlobalInit();
+}
+
+void
+NS_ShutdownNativeCharsetUtils()
+{
+  nsNativeCharsetConverter::GlobalShutdown();
+}
+
+//-----------------------------------------------------------------------------
+// XP_WIN
+//-----------------------------------------------------------------------------
+#elif defined(XP_WIN)
+
+#include <windows.h>
+#include "nsString.h"
+#include "nsAString.h"
+#include "nsReadableUtils.h"
+
+using namespace mozilla;
+
+nsresult
+NS_CopyNativeToUnicode(const nsACString& aInput, nsAString& aOutput)
+{
+  uint32_t inputLen = aInput.Length();
+
+  nsACString::const_iterator iter;
+  aInput.BeginReading(iter);
+
+  const char* buf = iter.get();
+
+  // determine length of result
+  uint32_t resultLen = 0;
+  int n = ::MultiByteToWideChar(CP_ACP, 0, buf, inputLen, nullptr, 0);
+  if (n > 0) {
+    resultLen += n;
+  }
+
+  // allocate sufficient space
+  if (!aOutput.SetLength(resultLen, fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  if (resultLen > 0) {
+    nsAString::iterator out_iter;
+    aOutput.BeginWriting(out_iter);
+
+    char16_t* result = out_iter.get();
+
+    ::MultiByteToWideChar(CP_ACP, 0, buf, inputLen, wwc(result), resultLen);
+  }
+  return NS_OK;
+}
+
+nsresult
+NS_CopyUnicodeToNative(const nsAString&  aInput, nsACString& aOutput)
+{
+  uint32_t inputLen = aInput.Length();
+
+  nsAString::const_iterator iter;
+  aInput.BeginReading(iter);
+
+  char16ptr_t buf = iter.get();
+
+  // determine length of result
+  uint32_t resultLen = 0;
+
+  int n = ::WideCharToMultiByte(CP_ACP, 0, buf, inputLen, nullptr, 0,
+                                nullptr, nullptr);
+  if (n > 0) {
+    resultLen += n;
+  }
+
+  // allocate sufficient space
+  if (!aOutput.SetLength(resultLen, fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  if (resultLen > 0) {
+    nsACString::iterator out_iter;
+    aOutput.BeginWriting(out_iter);
+
+    // default "defaultChar" is '?', which is an illegal character on windows
+    // file system.  That will cause file uncreatable. Change it to '_'
+    const char defaultChar = '_';
+
+    char* result = out_iter.get();
+
+    ::WideCharToMultiByte(CP_ACP, 0, buf, inputLen, result, resultLen,
+                          &defaultChar, nullptr);
+  }
+  return NS_OK;
+}
+
+// moved from widget/windows/nsToolkit.cpp
+int32_t
+NS_ConvertAtoW(const char* aStrInA, int aBufferSize, char16_t* aStrOutW)
+{
+  return MultiByteToWideChar(CP_ACP, 0, aStrInA, -1, wwc(aStrOutW), aBufferSize);
+}
+
+int32_t
+NS_ConvertWtoA(const char16_t* aStrInW, int aBufferSizeOut,
+               char* aStrOutA, const char* aDefault)
+{
+  if ((!aStrInW) || (!aStrOutA) || (aBufferSizeOut <= 0)) {
+    return 0;
+  }
+
+  int numCharsConverted = WideCharToMultiByte(CP_ACP, 0, char16ptr_t(aStrInW), -1,
+                                              aStrOutA, aBufferSizeOut,
+                                              aDefault, nullptr);
+
+  if (!numCharsConverted) {
+    if (GetLastError() == ERROR_INSUFFICIENT_BUFFER) {
+      // Overflow, add missing null termination but return 0
+      aStrOutA[aBufferSizeOut - 1] = '\0';
+    } else {
+      // Other error, clear string and return 0
+      aStrOutA[0] = '\0';
+    }
+  } else if (numCharsConverted < aBufferSizeOut) {
+    // Add 2nd null (really necessary?)
+    aStrOutA[numCharsConverted] = '\0';
+  }
+
+  return numCharsConverted;
+}
+
+#else
+
+#include "nsReadableUtils.h"
+
+nsresult
+NS_CopyNativeToUnicode(const nsACString& aInput, nsAString& aOutput)
+{
+  CopyASCIItoUTF16(aInput, aOutput);
+  return NS_OK;
+}
+
+nsresult
+NS_CopyUnicodeToNative(const nsAString& aInput, nsACString& aOutput)
+{
+  LossyCopyUTF16toASCII(aInput, aOutput);
+  return NS_OK;
+}
+
+void
+NS_StartupNativeCharsetUtils()
+{
+}
+
+void
+NS_ShutdownNativeCharsetUtils()
+{
+}
+
+#endif
diff --git a/xpcom/io/nsNativeCharsetUtils.h b/xpcom/io/nsNativeCharsetUtils.h
new file mode 100644
index 000000000..5c1e670d5
--- /dev/null
+++ b/xpcom/io/nsNativeCharsetUtils.h
@@ -0,0 +1,63 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsNativeCharsetUtils_h__
+#define nsNativeCharsetUtils_h__
+
+
+/*****************************************************************************\
+ *                                                                           *
+ *                             **** NOTICE ****                              *
+ *                                                                           *
+ *             *** THESE ARE NOT GENERAL PURPOSE CONVERTERS ***              *
+ *                                                                           *
+ *    NS_CopyNativeToUnicode / NS_CopyUnicodeToNative should only be used    *
+ *    for converting *FILENAMES* between native and unicode. They are not    *
+ *    designed or tested for general encoding converter use.                 *
+ *                                                                           *
+\*****************************************************************************/
+
+/**
+ * thread-safe conversion routines that do not depend on uconv libraries.
+ */
+nsresult NS_CopyNativeToUnicode(const nsACString& aInput, nsAString& aOutput);
+nsresult NS_CopyUnicodeToNative(const nsAString& aInput, nsACString& aOutput);
+
+/*
+ * This function indicates whether the character encoding used in the file
+ * system (more exactly what's used for |GetNativeFoo| and |SetNativeFoo|
+ * of |nsIFile|) is UTF-8 or not. Knowing that helps us avoid an
+ * unncessary encoding conversion in some cases. For instance, to get the leaf
+ * name in UTF-8 out of nsIFile, we can just use |GetNativeLeafName| rather
+ * than using |GetLeafName| and converting the result to UTF-8 if the file
+ * system  encoding is UTF-8.
+ * On Unix (but not on Mac OS X), it depends on the locale and is not known
+ * in advance (at the compilation time) so that this function needs to be
+ * a real function. On Mac OS X it's always UTF-8 while on Windows
+ * and other platforms (e.g. OS2), it's never UTF-8.
+ */
+#if defined(XP_UNIX) && !defined(XP_MACOSX) && !defined(ANDROID)
+bool NS_IsNativeUTF8();
+#else
+inline bool
+NS_IsNativeUTF8()
+{
+#if defined(XP_MACOSX) || defined(ANDROID)
+  return true;
+#else
+  return false;
+#endif
+}
+#endif
+
+
+/**
+ * internal
+ */
+void NS_StartupNativeCharsetUtils();
+void NS_ShutdownNativeCharsetUtils();
+
+#endif // nsNativeCharsetUtils_h__
diff --git a/xpcom/io/nsPipe.h b/xpcom/io/nsPipe.h
new file mode 100644
index 000000000..29ce0ce96
--- /dev/null
+++ b/xpcom/io/nsPipe.h
@@ -0,0 +1,24 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsPipe_h__
+#define nsPipe_h__
+
+#define NS_PIPE_CONTRACTID \
+  "@mozilla.org/pipe;1"
+#define NS_PIPE_CID \
+{ /* e4a0ee4e-0775-457b-9118-b3ae97a7c758 */ \
+  0xe4a0ee4e,                                \
+  0x0775,                                    \
+  0x457b,                                    \
+  {0x91,0x18,0xb3,0xae,0x97,0xa7,0xc7,0x58}  \
+}
+
+// Generic factory constructor for the nsPipe class
+nsresult
+nsPipeConstructor(nsISupports* outer, REFNSIID iid, void** result);
+
+#endif  // !defined(nsPipe_h__)
diff --git a/xpcom/io/nsPipe3.cpp b/xpcom/io/nsPipe3.cpp
new file mode 100644
index 000000000..56932adfc
--- /dev/null
+++ b/xpcom/io/nsPipe3.cpp
@@ -0,0 +1,2007 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <algorithm>
+#include "mozilla/Attributes.h"
+#include "mozilla/ReentrantMonitor.h"
+#include "nsIBufferedStreams.h"
+#include "nsICloneableInputStream.h"
+#include "nsIPipe.h"
+#include "nsIEventTarget.h"
+#include "nsISeekableStream.h"
+#include "mozilla/RefPtr.h"
+#include "nsSegmentedBuffer.h"
+#include "nsStreamUtils.h"
+#include "nsCOMPtr.h"
+#include "nsCRT.h"
+#include "mozilla/Logging.h"
+#include "nsIClassInfoImpl.h"
+#include "nsAlgorithm.h"
+#include "nsMemory.h"
+#include "nsIAsyncInputStream.h"
+#include "nsIAsyncOutputStream.h"
+
+using namespace mozilla;
+
+#ifdef LOG
+#undef LOG
+#endif
+//
+// set MOZ_LOG=nsPipe:5
+//
+static LazyLogModule sPipeLog("nsPipe");
+#define LOG(args) MOZ_LOG(sPipeLog, mozilla::LogLevel::Debug, args)
+
+#define DEFAULT_SEGMENT_SIZE  4096
+#define DEFAULT_SEGMENT_COUNT 16
+
+class nsPipe;
+class nsPipeEvents;
+class nsPipeInputStream;
+class nsPipeOutputStream;
+class AutoReadSegment;
+
+namespace {
+
+enum MonitorAction
+{
+  DoNotNotifyMonitor,
+  NotifyMonitor
+};
+
+enum SegmentChangeResult
+{
+  SegmentNotChanged,
+  SegmentAdvanceBufferRead
+};
+
+} // namespace
+
+//-----------------------------------------------------------------------------
+
+// this class is used to delay notifications until the end of a particular
+// scope.  it helps avoid the complexity of issuing callbacks while inside
+// a critical section.
+class nsPipeEvents
+{
+public:
+  nsPipeEvents() { }
+  ~nsPipeEvents();
+
+  inline void NotifyInputReady(nsIAsyncInputStream* aStream,
+                               nsIInputStreamCallback* aCallback)
+  {
+    mInputList.AppendElement(InputEntry(aStream, aCallback));
+  }
+
+  inline void NotifyOutputReady(nsIAsyncOutputStream* aStream,
+                                nsIOutputStreamCallback* aCallback)
+  {
+    NS_ASSERTION(!mOutputCallback, "already have an output event");
+    mOutputStream = aStream;
+    mOutputCallback = aCallback;
+  }
+
+private:
+  struct InputEntry
+  {
+    InputEntry(nsIAsyncInputStream* aStream, nsIInputStreamCallback* aCallback)
+      : mStream(aStream)
+      , mCallback(aCallback)
+    {
+      MOZ_ASSERT(mStream);
+      MOZ_ASSERT(mCallback);
+    }
+
+    nsCOMPtr<nsIAsyncInputStream> mStream;
+    nsCOMPtr<nsIInputStreamCallback> mCallback;
+  };
+
+  nsTArray<InputEntry> mInputList;
+
+  nsCOMPtr<nsIAsyncOutputStream>    mOutputStream;
+  nsCOMPtr<nsIOutputStreamCallback> mOutputCallback;
+};
+
+//-----------------------------------------------------------------------------
+
+// This class is used to maintain input stream state.  Its broken out from the
+// nsPipeInputStream class because generally the nsPipe should be modifying
+// this state and not the input stream itself.
+struct nsPipeReadState
+{
+  nsPipeReadState()
+    : mReadCursor(nullptr)
+    , mReadLimit(nullptr)
+    , mSegment(0)
+    , mAvailable(0)
+    , mActiveRead(false)
+    , mNeedDrain(false)
+  { }
+
+  char*    mReadCursor;
+  char*    mReadLimit;
+  int32_t  mSegment;
+  uint32_t mAvailable;
+
+  // This flag is managed using the AutoReadSegment RAII stack class.
+  bool     mActiveRead;
+
+  // Set to indicate that the input stream has closed and should be drained,
+  // but that drain has been delayed due to an active read.  When the read
+  // completes, this flag indicate the drain should then be performed.
+  bool     mNeedDrain;
+};
+
+//-----------------------------------------------------------------------------
+
+// an input end of a pipe (maintained as a list of refs within the pipe)
+class nsPipeInputStream final
+  : public nsIAsyncInputStream
+  , public nsISeekableStream
+  , public nsISearchableInputStream
+  , public nsICloneableInputStream
+  , public nsIClassInfo
+  , public nsIBufferedInputStream
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIINPUTSTREAM
+  NS_DECL_NSIASYNCINPUTSTREAM
+  NS_DECL_NSISEEKABLESTREAM
+  NS_DECL_NSISEARCHABLEINPUTSTREAM
+  NS_DECL_NSICLONEABLEINPUTSTREAM
+  NS_DECL_NSICLASSINFO
+  NS_DECL_NSIBUFFEREDINPUTSTREAM
+
+  explicit nsPipeInputStream(nsPipe* aPipe)
+    : mPipe(aPipe)
+    , mLogicalOffset(0)
+    , mInputStatus(NS_OK)
+    , mBlocking(true)
+    , mBlocked(false)
+    , mCallbackFlags(0)
+  { }
+
+  explicit nsPipeInputStream(const nsPipeInputStream& aOther)
+    : mPipe(aOther.mPipe)
+    , mLogicalOffset(aOther.mLogicalOffset)
+    , mInputStatus(aOther.mInputStatus)
+    , mBlocking(aOther.mBlocking)
+    , mBlocked(false)
+    , mCallbackFlags(0)
+    , mReadState(aOther.mReadState)
+  { }
+
+  nsresult Fill();
+  void SetNonBlocking(bool aNonBlocking)
+  {
+    mBlocking = !aNonBlocking;
+  }
+
+  uint32_t Available();
+
+  // synchronously wait for the pipe to become readable.
+  nsresult Wait();
+
+  // These two don't acquire the monitor themselves.  Instead they
+  // expect their caller to have done so and to pass the monitor as
+  // evidence.
+  MonitorAction OnInputReadable(uint32_t aBytesWritten, nsPipeEvents&,
+                                const ReentrantMonitorAutoEnter& ev);
+  MonitorAction OnInputException(nsresult, nsPipeEvents&,
+                                 const ReentrantMonitorAutoEnter& ev);
+
+  nsPipeReadState& ReadState()
+  {
+    return mReadState;
+  }
+
+  const nsPipeReadState& ReadState() const
+  {
+    return mReadState;
+  }
+
+  nsresult Status() const;
+
+  // A version of Status() that doesn't acquire the monitor.
+  nsresult Status(const ReentrantMonitorAutoEnter& ev) const;
+
+private:
+  virtual ~nsPipeInputStream();
+
+  RefPtr<nsPipe>               mPipe;
+
+  int64_t                        mLogicalOffset;
+  // Individual input streams can be closed without effecting the rest of the
+  // pipe.  So track individual input stream status separately.  |mInputStatus|
+  // is protected by |mPipe->mReentrantMonitor|.
+  nsresult                       mInputStatus;
+  bool                           mBlocking;
+
+  // these variables can only be accessed while inside the pipe's monitor
+  bool                           mBlocked;
+  nsCOMPtr<nsIInputStreamCallback> mCallback;
+  uint32_t                       mCallbackFlags;
+
+  // requires pipe's monitor; usually treat as an opaque token to pass to nsPipe
+  nsPipeReadState                mReadState;
+};
+
+//-----------------------------------------------------------------------------
+
+// the output end of a pipe (allocated as a member of the pipe).
+class nsPipeOutputStream
+  : public nsIAsyncOutputStream
+  , public nsIClassInfo
+{
+public:
+  // since this class will be allocated as a member of the pipe, we do not
+  // need our own ref count.  instead, we share the lifetime (the ref count)
+  // of the entire pipe.  this macro is just convenience since it does not
+  // declare a mRefCount variable; however, don't let the name fool you...
+  // we are not inheriting from nsPipe ;-)
+  NS_DECL_ISUPPORTS_INHERITED
+
+  NS_DECL_NSIOUTPUTSTREAM
+  NS_DECL_NSIASYNCOUTPUTSTREAM
+  NS_DECL_NSICLASSINFO
+
+  explicit nsPipeOutputStream(nsPipe* aPipe)
+    : mPipe(aPipe)
+    , mWriterRefCnt(0)
+    , mLogicalOffset(0)
+    , mBlocking(true)
+    , mBlocked(false)
+    , mWritable(true)
+    , mCallbackFlags(0)
+  { }
+
+  void SetNonBlocking(bool aNonBlocking)
+  {
+    mBlocking = !aNonBlocking;
+  }
+  void SetWritable(bool aWritable)
+  {
+    mWritable = aWritable;
+  }
+
+  // synchronously wait for the pipe to become writable.
+  nsresult Wait();
+
+  MonitorAction OnOutputWritable(nsPipeEvents&);
+  MonitorAction OnOutputException(nsresult, nsPipeEvents&);
+
+private:
+  nsPipe*                         mPipe;
+
+  // separate refcnt so that we know when to close the producer
+  mozilla::ThreadSafeAutoRefCnt   mWriterRefCnt;
+  int64_t                         mLogicalOffset;
+  bool                            mBlocking;
+
+  // these variables can only be accessed while inside the pipe's monitor
+  bool                            mBlocked;
+  bool                            mWritable;
+  nsCOMPtr<nsIOutputStreamCallback> mCallback;
+  uint32_t                        mCallbackFlags;
+};
+
+//-----------------------------------------------------------------------------
+
+class nsPipe final : public nsIPipe
+{
+public:
+  friend class nsPipeInputStream;
+  friend class nsPipeOutputStream;
+  friend class AutoReadSegment;
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIPIPE
+
+  // nsPipe methods:
+  nsPipe();
+
+private:
+  ~nsPipe();
+
+  //
+  // Methods below may only be called while inside the pipe's monitor.  Some
+  // of these methods require passing a ReentrantMonitorAutoEnter to prove the
+  // monitor is held.
+  //
+
+  void PeekSegment(const nsPipeReadState& aReadState, uint32_t aIndex,
+                   char*& aCursor, char*& aLimit);
+  SegmentChangeResult AdvanceReadSegment(nsPipeReadState& aReadState,
+                                         const ReentrantMonitorAutoEnter &ev);
+  bool ReadSegmentBeingWritten(nsPipeReadState& aReadState);
+  uint32_t CountSegmentReferences(int32_t aSegment);
+  void SetAllNullReadCursors();
+  bool AllReadCursorsMatchWriteCursor();
+  void RollBackAllReadCursors(char* aWriteCursor);
+  void UpdateAllReadCursors(char* aWriteCursor);
+  void ValidateAllReadCursors();
+  uint32_t GetBufferSegmentCount(const nsPipeReadState& aReadState,
+                                 const ReentrantMonitorAutoEnter& ev) const;
+  bool IsAdvanceBufferFull(const ReentrantMonitorAutoEnter& ev) const;
+
+  //
+  // methods below may be called while outside the pipe's monitor
+  //
+
+  void     DrainInputStream(nsPipeReadState& aReadState, nsPipeEvents& aEvents);
+  nsresult GetWriteSegment(char*& aSegment, uint32_t& aSegmentLen);
+  void     AdvanceWriteCursor(uint32_t aCount);
+
+  void     OnInputStreamException(nsPipeInputStream* aStream, nsresult aReason);
+  void     OnPipeException(nsresult aReason, bool aOutputOnly = false);
+
+  nsresult CloneInputStream(nsPipeInputStream* aOriginal,
+                            nsIInputStream** aCloneOut);
+
+  // methods below should only be called by AutoReadSegment
+  nsresult GetReadSegment(nsPipeReadState& aReadState, const char*& aSegment,
+                          uint32_t& aLength);
+  void     ReleaseReadSegment(nsPipeReadState& aReadState,
+                              nsPipeEvents& aEvents);
+  void     AdvanceReadCursor(nsPipeReadState& aReadState, uint32_t aCount);
+
+  // We can't inherit from both nsIInputStream and nsIOutputStream
+  // because they collide on their Close method. Consequently we nest their
+  // implementations to avoid the extra object allocation.
+  nsPipeOutputStream  mOutput;
+
+  // Since the input stream can be cloned, we may have more than one.  Use
+  // a weak reference as the streams will clear their entry here in their
+  // destructor.  Using a strong reference would create a reference cycle.
+  // Only usable while mReentrantMonitor is locked.
+  nsTArray<nsPipeInputStream*> mInputList;
+
+  // But hold a strong ref to our original input stream.  For backward
+  // compatibility we need to be able to consistently return this same
+  // object from GetInputStream().  Note, mOriginalInput is also stored
+  // in mInputList as a weak ref.
+  RefPtr<nsPipeInputStream> mOriginalInput;
+
+  ReentrantMonitor    mReentrantMonitor;
+  nsSegmentedBuffer   mBuffer;
+
+  // The maximum number of segments to allow to be buffered in advance
+  // of the fastest reader.  This is collection of segments is called
+  // the "advance buffer".
+  uint32_t            mMaxAdvanceBufferSegmentCount;
+
+  int32_t             mWriteSegment;
+  char*               mWriteCursor;
+  char*               mWriteLimit;
+
+  // |mStatus| is protected by |mReentrantMonitor|.
+  nsresult            mStatus;
+  bool                mInited;
+};
+
+//-----------------------------------------------------------------------------
+
+// RAII class representing an active read segment.  When it goes out of scope
+// it automatically updates the read cursor and releases the read segment.
+class MOZ_STACK_CLASS AutoReadSegment final
+{
+public:
+  AutoReadSegment(nsPipe* aPipe, nsPipeReadState& aReadState,
+                  uint32_t aMaxLength)
+    : mPipe(aPipe)
+    , mReadState(aReadState)
+    , mStatus(NS_ERROR_FAILURE)
+    , mSegment(nullptr)
+    , mLength(0)
+    , mOffset(0)
+  {
+    MOZ_ASSERT(mPipe);
+    MOZ_ASSERT(!mReadState.mActiveRead);
+    mStatus = mPipe->GetReadSegment(mReadState, mSegment, mLength);
+    if (NS_SUCCEEDED(mStatus)) {
+      MOZ_ASSERT(mReadState.mActiveRead);
+      MOZ_ASSERT(mSegment);
+      mLength = std::min(mLength, aMaxLength);
+      MOZ_ASSERT(mLength);
+    }
+  }
+
+  ~AutoReadSegment()
+  {
+    if (NS_SUCCEEDED(mStatus)) {
+      if (mOffset) {
+        mPipe->AdvanceReadCursor(mReadState, mOffset);
+      } else {
+        nsPipeEvents events;
+        mPipe->ReleaseReadSegment(mReadState, events);
+      }
+    }
+    MOZ_ASSERT(!mReadState.mActiveRead);
+  }
+
+  nsresult Status() const
+  {
+    return mStatus;
+  }
+
+  const char* Data() const
+  {
+    MOZ_ASSERT(NS_SUCCEEDED(mStatus));
+    MOZ_ASSERT(mSegment);
+    return mSegment + mOffset;
+  }
+
+  uint32_t Length() const
+  {
+    MOZ_ASSERT(NS_SUCCEEDED(mStatus));
+    MOZ_ASSERT(mLength >= mOffset);
+    return mLength - mOffset;
+  }
+
+  void
+  Advance(uint32_t aCount)
+  {
+    MOZ_ASSERT(NS_SUCCEEDED(mStatus));
+    MOZ_ASSERT(aCount <= (mLength - mOffset));
+    mOffset += aCount;
+  }
+
+  nsPipeReadState&
+  ReadState() const
+  {
+    return mReadState;
+  }
+
+private:
+  // guaranteed to remain alive due to limited stack lifetime of AutoReadSegment
+  nsPipe* mPipe;
+  nsPipeReadState& mReadState;
+  nsresult mStatus;
+  const char* mSegment;
+  uint32_t mLength;
+  uint32_t mOffset;
+};
+
+//
+// NOTES on buffer architecture:
+//
+//       +-----------------+ - - mBuffer.GetSegment(0)
+//       |                 |
+//       + - - - - - - - - + - - nsPipeReadState.mReadCursor
+//       |/////////////////|
+//       |/////////////////|
+//       |/////////////////|
+//       |/////////////////|
+//       +-----------------+ - - nsPipeReadState.mReadLimit
+//                |
+//       +-----------------+
+//       |/////////////////|
+//       |/////////////////|
+//       |/////////////////|
+//       |/////////////////|
+//       |/////////////////|
+//       |/////////////////|
+//       +-----------------+
+//                |
+//       +-----------------+ - - mBuffer.GetSegment(mWriteSegment)
+//       |/////////////////|
+//       |/////////////////|
+//       |/////////////////|
+//       + - - - - - - - - + - - mWriteCursor
+//       |                 |
+//       |                 |
+//       +-----------------+ - - mWriteLimit
+//
+// (shaded region contains data)
+//
+// NOTE: Each input stream produced by the nsPipe contains its own, separate
+//       nsPipeReadState.  This means there are multiple mReadCursor and
+//       mReadLimit values in play.  The pipe cannot discard old data until
+//       all mReadCursors have moved beyond that point in the stream.
+//
+//       Likewise, each input stream reader will have it's own amount of
+//       buffered data.  The pipe size threshold, however, is only applied
+//       to the input stream that is being read fastest.  We call this
+//       the "advance buffer" in that its in advance of all readers.  We
+//       allow slower input streams to buffer more data so that we don't
+//       stall processing of the faster input stream.
+//
+// NOTE: on some systems (notably OS/2), the heap allocator uses an arena for
+// small allocations (e.g., 64 byte allocations).  this means that buffers may
+// be allocated back-to-back.  in the diagram above, for example, mReadLimit
+// would actually be pointing at the beginning of the next segment.  when
+// making changes to this file, please keep this fact in mind.
+//
+
+//-----------------------------------------------------------------------------
+// nsPipe methods:
+//-----------------------------------------------------------------------------
+
+nsPipe::nsPipe()
+  : mOutput(this)
+  , mOriginalInput(new nsPipeInputStream(this))
+  , mReentrantMonitor("nsPipe.mReentrantMonitor")
+  , mMaxAdvanceBufferSegmentCount(0)
+  , mWriteSegment(-1)
+  , mWriteCursor(nullptr)
+  , mWriteLimit(nullptr)
+  , mStatus(NS_OK)
+  , mInited(false)
+{
+  mInputList.AppendElement(mOriginalInput);
+}
+
+nsPipe::~nsPipe()
+{
+}
+
+NS_IMPL_ADDREF(nsPipe)
+NS_IMPL_QUERY_INTERFACE(nsPipe, nsIPipe)
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsPipe::Release()
+{
+  MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");
+  nsrefcnt count = --mRefCnt;
+  NS_LOG_RELEASE(this, count, "nsPipe");
+  if (count == 0) {
+    delete (this);
+    return 0;
+  }
+  // Avoid racing on |mOriginalInput| by only looking at it when
+  // the refcount is 1, that is, we are the only pointer (hence only
+  // thread) to access it.
+  if (count == 1 && mOriginalInput) {
+    mOriginalInput = nullptr;
+    return 1;
+  }
+  return count;
+}
+
+NS_IMETHODIMP
+nsPipe::Init(bool aNonBlockingIn,
+             bool aNonBlockingOut,
+             uint32_t aSegmentSize,
+             uint32_t aSegmentCount)
+{
+  mInited = true;
+
+  if (aSegmentSize == 0) {
+    aSegmentSize = DEFAULT_SEGMENT_SIZE;
+  }
+  if (aSegmentCount == 0) {
+    aSegmentCount = DEFAULT_SEGMENT_COUNT;
+  }
+
+  // protect against overflow
+  uint32_t maxCount = uint32_t(-1) / aSegmentSize;
+  if (aSegmentCount > maxCount) {
+    aSegmentCount = maxCount;
+  }
+
+  // The internal buffer is always "infinite" so that we can allow
+  // the size to expand when cloned streams are read at different
+  // rates.  We enforce a limit on how much data can be buffered
+  // ahead of the fastest reader in GetWriteSegment().
+  nsresult rv = mBuffer.Init(aSegmentSize, UINT32_MAX);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  mMaxAdvanceBufferSegmentCount = aSegmentCount;
+
+  mOutput.SetNonBlocking(aNonBlockingOut);
+  mOriginalInput->SetNonBlocking(aNonBlockingIn);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipe::GetInputStream(nsIAsyncInputStream** aInputStream)
+{
+  if (NS_WARN_IF(!mInited)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  RefPtr<nsPipeInputStream> ref = mOriginalInput;
+  ref.forget(aInputStream);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipe::GetOutputStream(nsIAsyncOutputStream** aOutputStream)
+{
+  if (NS_WARN_IF(!mInited)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  NS_ADDREF(*aOutputStream = &mOutput);
+  return NS_OK;
+}
+
+void
+nsPipe::PeekSegment(const nsPipeReadState& aReadState, uint32_t aIndex,
+                    char*& aCursor, char*& aLimit)
+{
+  if (aIndex == 0) {
+    NS_ASSERTION(!aReadState.mReadCursor || mBuffer.GetSegmentCount(),
+                 "unexpected state");
+    aCursor = aReadState.mReadCursor;
+    aLimit = aReadState.mReadLimit;
+  } else {
+    uint32_t absoluteIndex = aReadState.mSegment + aIndex;
+    uint32_t numSegments = mBuffer.GetSegmentCount();
+    if (absoluteIndex >= numSegments) {
+      aCursor = aLimit = nullptr;
+    } else {
+      aCursor = mBuffer.GetSegment(absoluteIndex);
+      if (mWriteSegment == (int32_t)absoluteIndex) {
+        aLimit = mWriteCursor;
+      } else {
+        aLimit = aCursor + mBuffer.GetSegmentSize();
+      }
+    }
+  }
+}
+
+nsresult
+nsPipe::GetReadSegment(nsPipeReadState& aReadState, const char*& aSegment,
+                       uint32_t& aLength)
+{
+  ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+
+  if (aReadState.mReadCursor == aReadState.mReadLimit) {
+    return NS_FAILED(mStatus) ? mStatus : NS_BASE_STREAM_WOULD_BLOCK;
+  }
+
+  // The input stream locks the pipe while getting the buffer to read from,
+  // but then unlocks while actual data copying is taking place.  In
+  // order to avoid deleting the buffer out from under this lockless read
+  // set a flag to indicate a read is active.  This flag is only modified
+  // while the lock is held.
+  MOZ_ASSERT(!aReadState.mActiveRead);
+  aReadState.mActiveRead = true;
+
+  aSegment = aReadState.mReadCursor;
+  aLength = aReadState.mReadLimit - aReadState.mReadCursor;
+
+  return NS_OK;
+}
+
+void
+nsPipe::ReleaseReadSegment(nsPipeReadState& aReadState, nsPipeEvents& aEvents)
+{
+  ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+
+  MOZ_ASSERT(aReadState.mActiveRead);
+  aReadState.mActiveRead = false;
+
+  // When a read completes and releases the mActiveRead flag, we may have blocked
+  // a drain from completing.  This occurs when the input stream is closed during
+  // the read.  In these cases, we need to complete the drain as soon as the
+  // active read completes.
+  if (aReadState.mNeedDrain) {
+    aReadState.mNeedDrain = false;
+    DrainInputStream(aReadState, aEvents);
+  }
+}
+
+void
+nsPipe::AdvanceReadCursor(nsPipeReadState& aReadState, uint32_t aBytesRead)
+{
+  NS_ASSERTION(aBytesRead, "don't call if no bytes read");
+
+  nsPipeEvents events;
+  {
+    ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+
+    LOG(("III advancing read cursor by %u\n", aBytesRead));
+    NS_ASSERTION(aBytesRead <= mBuffer.GetSegmentSize(), "read too much");
+
+    aReadState.mReadCursor += aBytesRead;
+    NS_ASSERTION(aReadState.mReadCursor <= aReadState.mReadLimit,
+                 "read cursor exceeds limit");
+
+    MOZ_ASSERT(aReadState.mAvailable >= aBytesRead);
+    aReadState.mAvailable -= aBytesRead;
+
+    // Check to see if we're at the end of the available read data.  If we
+    // are, and this segment is not still being written, then we can possibly
+    // free up the segment.
+    if (aReadState.mReadCursor == aReadState.mReadLimit &&
+        !ReadSegmentBeingWritten(aReadState)) {
+
+      // Advance the segment position.  If we have read any segments from the
+      // advance buffer then we can potentially notify blocked writers.
+      if (AdvanceReadSegment(aReadState, mon) == SegmentAdvanceBufferRead &&
+          mOutput.OnOutputWritable(events) == NotifyMonitor) {
+        mon.NotifyAll();
+      }
+    }
+
+    ReleaseReadSegment(aReadState, events);
+  }
+}
+
+SegmentChangeResult
+nsPipe::AdvanceReadSegment(nsPipeReadState& aReadState,
+                           const ReentrantMonitorAutoEnter &ev)
+{
+  // Calculate how many segments are buffered for this stream to start.
+  uint32_t startBufferSegments = GetBufferSegmentCount(aReadState, ev);
+
+  int32_t currentSegment = aReadState.mSegment;
+
+  // Move to the next segment to read
+  aReadState.mSegment += 1;
+
+  // If this was the last reference to the first segment, then remove it.
+  if (currentSegment == 0 && CountSegmentReferences(currentSegment) == 0) {
+
+    // shift write and read segment index (-1 indicates an empty buffer).
+    mWriteSegment -= 1;
+
+    // Directly modify the current read state.  If the associated input
+    // stream is closed simultaneous with reading, then it may not be
+    // in the mInputList any more.
+    aReadState.mSegment -= 1;
+
+    for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+      // Skip the current read state structure since we modify it manually
+      // before entering this loop.
+      if (&mInputList[i]->ReadState() == &aReadState) {
+        continue;
+      }
+      mInputList[i]->ReadState().mSegment -= 1;
+    }
+
+    // done with this segment
+    mBuffer.DeleteFirstSegment();
+    LOG(("III deleting first segment\n"));
+  }
+
+  if (mWriteSegment < aReadState.mSegment) {
+    // read cursor has hit the end of written data, so reset it
+    MOZ_ASSERT(mWriteSegment == (aReadState.mSegment - 1));
+    aReadState.mReadCursor = nullptr;
+    aReadState.mReadLimit = nullptr;
+    // also, the buffer is completely empty, so reset the write cursor
+    if (mWriteSegment == -1) {
+      mWriteCursor = nullptr;
+      mWriteLimit = nullptr;
+    }
+  } else {
+    // advance read cursor and limit to next buffer segment
+    aReadState.mReadCursor = mBuffer.GetSegment(aReadState.mSegment);
+    if (mWriteSegment == aReadState.mSegment) {
+      aReadState.mReadLimit = mWriteCursor;
+    } else {
+      aReadState.mReadLimit = aReadState.mReadCursor + mBuffer.GetSegmentSize();
+    }
+  }
+
+  // Calculate how many segments are buffered for the stream after
+  // reading.
+  uint32_t endBufferSegments = GetBufferSegmentCount(aReadState, ev);
+
+  // If the stream has read a segment out of the set of advanced buffer
+  // segments, then the writer may advance.
+  if (startBufferSegments >= mMaxAdvanceBufferSegmentCount &&
+      endBufferSegments < mMaxAdvanceBufferSegmentCount) {
+    return SegmentAdvanceBufferRead;
+  }
+
+  // Otherwise there are no significant changes to the segment structure.
+  return SegmentNotChanged;
+}
+
+void
+nsPipe::DrainInputStream(nsPipeReadState& aReadState, nsPipeEvents& aEvents)
+{
+  ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+
+  // If a segment is actively being read in ReadSegments() for this input
+  // stream, then we cannot drain the stream.  This can happen because
+  // ReadSegments() does not hold the lock while copying from the buffer.
+  // If we detect this condition, simply note that we need a drain once
+  // the read completes and return immediately.
+  if (aReadState.mActiveRead) {
+    MOZ_ASSERT(!aReadState.mNeedDrain);
+    aReadState.mNeedDrain = true;
+    return;
+  }
+
+  aReadState.mAvailable = 0;
+
+  while(mWriteSegment >= aReadState.mSegment) {
+
+    // If the last segment to free is still being written to, we're done
+    // draining.  We can't free any more.
+    if (ReadSegmentBeingWritten(aReadState)) {
+      break;
+    }
+
+    // Don't bother checking if this results in an advance buffer segment
+    // read.  Since we are draining the entire stream we will read an
+    // advance buffer segment no matter what.
+    AdvanceReadSegment(aReadState, mon);
+  }
+
+  // If we have read any segments from the advance buffer then we can
+  // potentially notify blocked writers.
+  if (!IsAdvanceBufferFull(mon) &&
+      mOutput.OnOutputWritable(aEvents) == NotifyMonitor) {
+    mon.NotifyAll();
+  }
+}
+
+bool
+nsPipe::ReadSegmentBeingWritten(nsPipeReadState& aReadState)
+{
+  mReentrantMonitor.AssertCurrentThreadIn();
+  bool beingWritten = mWriteSegment == aReadState.mSegment &&
+                      mWriteLimit > mWriteCursor;
+  NS_ASSERTION(!beingWritten || aReadState.mReadLimit == mWriteCursor,
+               "unexpected state");
+  return beingWritten;
+}
+
+nsresult
+nsPipe::GetWriteSegment(char*& aSegment, uint32_t& aSegmentLen)
+{
+  ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+
+  if (NS_FAILED(mStatus)) {
+    return mStatus;
+  }
+
+  // write cursor and limit may both be null indicating an empty buffer.
+  if (mWriteCursor == mWriteLimit) {
+    // The pipe is full if we have hit our limit on advance data buffering.
+    // This means the fastest reader is still reading slower than data is
+    // being written into the pipe.
+    if (IsAdvanceBufferFull(mon)) {
+      return NS_BASE_STREAM_WOULD_BLOCK;
+    }
+
+    // The nsSegmentedBuffer is configured to be "infinite", so this
+    // should never return nullptr here.
+    char* seg = mBuffer.AppendNewSegment();
+    if (!seg) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    LOG(("OOO appended new segment\n"));
+    mWriteCursor = seg;
+    mWriteLimit = mWriteCursor + mBuffer.GetSegmentSize();
+    ++mWriteSegment;
+  }
+
+  // make sure read cursor is initialized
+  SetAllNullReadCursors();
+
+  // check to see if we can roll-back our read and write cursors to the
+  // beginning of the current/first segment.  this is purely an optimization.
+  if (mWriteSegment == 0 && AllReadCursorsMatchWriteCursor()) {
+    char* head = mBuffer.GetSegment(0);
+    LOG(("OOO rolling back write cursor %u bytes\n", mWriteCursor - head));
+    RollBackAllReadCursors(head);
+    mWriteCursor = head;
+  }
+
+  aSegment    = mWriteCursor;
+  aSegmentLen = mWriteLimit - mWriteCursor;
+  return NS_OK;
+}
+
+void
+nsPipe::AdvanceWriteCursor(uint32_t aBytesWritten)
+{
+  NS_ASSERTION(aBytesWritten, "don't call if no bytes written");
+
+  nsPipeEvents events;
+  {
+    ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+
+    LOG(("OOO advancing write cursor by %u\n", aBytesWritten));
+
+    char* newWriteCursor = mWriteCursor + aBytesWritten;
+    NS_ASSERTION(newWriteCursor <= mWriteLimit, "write cursor exceeds limit");
+
+    // update read limit if reading in the same segment
+    UpdateAllReadCursors(newWriteCursor);
+
+    mWriteCursor = newWriteCursor;
+
+    ValidateAllReadCursors();
+
+    // update the writable flag on the output stream
+    if (mWriteCursor == mWriteLimit) {
+      mOutput.SetWritable(!IsAdvanceBufferFull(mon));
+    }
+
+    // notify input stream that pipe now contains additional data
+    bool needNotify = false;
+    for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+      if (mInputList[i]->OnInputReadable(aBytesWritten, events, mon)
+          == NotifyMonitor) {
+        needNotify = true;
+      }
+    }
+
+    if (needNotify) {
+      mon.NotifyAll();
+    }
+  }
+}
+
+void
+nsPipe::OnInputStreamException(nsPipeInputStream* aStream, nsresult aReason)
+{
+  MOZ_ASSERT(NS_FAILED(aReason));
+
+  nsPipeEvents events;
+  {
+    ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+
+    // Its possible to re-enter this method when we call OnPipeException() or
+    // OnInputExection() below.  If there is a caller stuck in our synchronous
+    // Wait() method, then they will get woken up with a failure code which
+    // re-enters this method.  Therefore, gracefully handle unknown streams
+    // here.
+
+    // If we only have one stream open and it is the given stream, then shut
+    // down the entire pipe.
+    if (mInputList.Length() == 1) {
+      if (mInputList[0] == aStream) {
+        OnPipeException(aReason);
+      }
+      return;
+    }
+
+    // Otherwise just close the particular stream that hit an exception.
+    for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+      if (mInputList[i] != aStream) {
+        continue;
+      }
+
+      MonitorAction action = mInputList[i]->OnInputException(aReason, events,
+                                                             mon);
+      mInputList.RemoveElementAt(i);
+
+      // Notify after element is removed in case we re-enter as a result.
+      if (action == NotifyMonitor) {
+        mon.NotifyAll();
+      }
+
+      return;
+    }
+  }
+}
+
+void
+nsPipe::OnPipeException(nsresult aReason, bool aOutputOnly)
+{
+  LOG(("PPP nsPipe::OnPipeException [reason=%x output-only=%d]\n",
+       aReason, aOutputOnly));
+
+  nsPipeEvents events;
+  {
+    ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+
+    // if we've already hit an exception, then ignore this one.
+    if (NS_FAILED(mStatus)) {
+      return;
+    }
+
+    mStatus = aReason;
+
+    bool needNotify = false;
+
+    nsTArray<nsPipeInputStream*> tmpInputList;
+    for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+      // an output-only exception applies to the input end if the pipe has
+      // zero bytes available.
+      if (aOutputOnly && mInputList[i]->Available()) {
+        tmpInputList.AppendElement(mInputList[i]);
+        continue;
+      }
+
+      if (mInputList[i]->OnInputException(aReason, events, mon)
+          == NotifyMonitor) {
+        needNotify = true;
+      }
+    }
+    mInputList = tmpInputList;
+
+    if (mOutput.OnOutputException(aReason, events) == NotifyMonitor) {
+      needNotify = true;
+    }
+
+    // Notify after we have removed any input streams from mInputList
+    if (needNotify) {
+      mon.NotifyAll();
+    }
+  }
+}
+
+nsresult
+nsPipe::CloneInputStream(nsPipeInputStream* aOriginal,
+                         nsIInputStream** aCloneOut)
+{
+  ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+  RefPtr<nsPipeInputStream> ref = new nsPipeInputStream(*aOriginal);
+  mInputList.AppendElement(ref);
+  nsCOMPtr<nsIAsyncInputStream> downcast = ref.forget();
+  downcast.forget(aCloneOut);
+  return NS_OK;
+}
+
+uint32_t
+nsPipe::CountSegmentReferences(int32_t aSegment)
+{
+  mReentrantMonitor.AssertCurrentThreadIn();
+  uint32_t count = 0;
+  for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+    if (aSegment >= mInputList[i]->ReadState().mSegment) {
+      count += 1;
+    }
+  }
+  return count;
+}
+
+void
+nsPipe::SetAllNullReadCursors()
+{
+  mReentrantMonitor.AssertCurrentThreadIn();
+  for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+    nsPipeReadState& readState = mInputList[i]->ReadState();
+    if (!readState.mReadCursor) {
+      NS_ASSERTION(mWriteSegment == readState.mSegment,
+                   "unexpected null read cursor");
+      readState.mReadCursor = readState.mReadLimit = mWriteCursor;
+    }
+  }
+}
+
+bool
+nsPipe::AllReadCursorsMatchWriteCursor()
+{
+  mReentrantMonitor.AssertCurrentThreadIn();
+  for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+    const nsPipeReadState& readState = mInputList[i]->ReadState();
+    if (readState.mSegment != mWriteSegment ||
+        readState.mReadCursor != mWriteCursor) {
+      return false;
+    }
+  }
+  return true;
+}
+
+void
+nsPipe::RollBackAllReadCursors(char* aWriteCursor)
+{
+  mReentrantMonitor.AssertCurrentThreadIn();
+  for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+    nsPipeReadState& readState = mInputList[i]->ReadState();
+    MOZ_ASSERT(mWriteSegment == readState.mSegment);
+    MOZ_ASSERT(mWriteCursor == readState.mReadCursor);
+    MOZ_ASSERT(mWriteCursor == readState.mReadLimit);
+    readState.mReadCursor = aWriteCursor;
+    readState.mReadLimit = aWriteCursor;
+  }
+}
+
+void
+nsPipe::UpdateAllReadCursors(char* aWriteCursor)
+{
+  mReentrantMonitor.AssertCurrentThreadIn();
+  for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+    nsPipeReadState& readState = mInputList[i]->ReadState();
+    if (mWriteSegment == readState.mSegment &&
+        readState.mReadLimit == mWriteCursor) {
+      readState.mReadLimit = aWriteCursor;
+    }
+  }
+}
+
+void
+nsPipe::ValidateAllReadCursors()
+{
+  mReentrantMonitor.AssertCurrentThreadIn();
+  // The only way mReadCursor == mWriteCursor is if:
+  //
+  // - mReadCursor is at the start of a segment (which, based on how
+  //   nsSegmentedBuffer works, means that this segment is the "first"
+  //   segment)
+  // - mWriteCursor points at the location past the end of the current
+  //   write segment (so the current write filled the current write
+  //   segment, so we've incremented mWriteCursor to point past the end
+  //   of it)
+  // - the segment to which data has just been written is located
+  //   exactly one segment's worth of bytes before the first segment
+  //   where mReadCursor is located
+  //
+  // Consequently, the byte immediately after the end of the current
+  // write segment is the first byte of the first segment, so
+  // mReadCursor == mWriteCursor.  (Another way to think about this is
+  // to consider the buffer architecture diagram above, but consider it
+  // with an arena allocator which allocates from the *end* of the
+  // arena to the *beginning* of the arena.)
+#ifdef DEBUG
+  for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+    const nsPipeReadState& state = mInputList[i]->ReadState();
+    NS_ASSERTION(state.mReadCursor != mWriteCursor ||
+                 (mBuffer.GetSegment(state.mSegment) == state.mReadCursor &&
+                  mWriteCursor == mWriteLimit),
+                 "read cursor is bad");
+  }
+#endif
+}
+
+uint32_t
+nsPipe::GetBufferSegmentCount(const nsPipeReadState& aReadState,
+                              const ReentrantMonitorAutoEnter& ev) const
+{
+  // The write segment can be smaller than the current reader position
+  // in some cases.  For example, when the first write segment has not
+  // been allocated yet mWriteSegment is negative.  In these cases
+  // the stream is effectively using zero segments.
+  if (mWriteSegment < aReadState.mSegment) {
+    return 0;
+  }
+
+  MOZ_ASSERT(mWriteSegment >= 0);
+  MOZ_ASSERT(aReadState.mSegment >= 0);
+
+  // Otherwise at least one segment is being used.  We add one here
+  // since a single segment is being used when the write and read
+  // segment indices are the same.
+  return 1 + mWriteSegment - aReadState.mSegment;
+}
+
+bool
+nsPipe::IsAdvanceBufferFull(const ReentrantMonitorAutoEnter& ev) const
+{
+  // If we have fewer total segments than the limit we can immediately
+  // determine we are not full.  Note, we must add one to mWriteSegment
+  // to convert from a index to a count.
+  MOZ_DIAGNOSTIC_ASSERT(mWriteSegment >= -1);
+  MOZ_DIAGNOSTIC_ASSERT(mWriteSegment < INT32_MAX);
+  uint32_t totalWriteSegments = mWriteSegment + 1;
+  if (totalWriteSegments < mMaxAdvanceBufferSegmentCount) {
+    return false;
+  }
+
+  // Otherwise we must inspect all of our reader streams.  We need
+  // to determine the buffer depth of the fastest reader.
+  uint32_t minBufferSegments = UINT32_MAX;
+  for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+    // Only count buffer segments from input streams that are open.
+    if (NS_FAILED(mInputList[i]->Status(ev))) {
+      continue;
+    }
+    const nsPipeReadState& state = mInputList[i]->ReadState();
+    uint32_t bufferSegments = GetBufferSegmentCount(state, ev);
+    minBufferSegments = std::min(minBufferSegments, bufferSegments);
+    // We only care if any reader has fewer segments buffered than
+    // our threshold.  We can stop once we hit that threshold.
+    if (minBufferSegments < mMaxAdvanceBufferSegmentCount) {
+      return false;
+    }
+  }
+
+  // Note, its possible for minBufferSegments to exceed our
+  // mMaxAdvanceBufferSegmentCount here.  This happens when a cloned
+  // reader gets far behind, but then the fastest reader stream is
+  // closed.  This leaves us with a single stream that is buffered
+  // beyond our max.  Naturally we continue to indicate the pipe
+  // is full at this point.
+
+  return true;
+}
+
+//-----------------------------------------------------------------------------
+// nsPipeEvents methods:
+//-----------------------------------------------------------------------------
+
+nsPipeEvents::~nsPipeEvents()
+{
+  // dispatch any pending events
+
+  for (uint32_t i = 0; i < mInputList.Length(); ++i) {
+    mInputList[i].mCallback->OnInputStreamReady(mInputList[i].mStream);
+  }
+  mInputList.Clear();
+
+  if (mOutputCallback) {
+    mOutputCallback->OnOutputStreamReady(mOutputStream);
+    mOutputCallback = nullptr;
+    mOutputStream = nullptr;
+  }
+}
+
+//-----------------------------------------------------------------------------
+// nsPipeInputStream methods:
+//-----------------------------------------------------------------------------
+
+NS_IMPL_ADDREF(nsPipeInputStream);
+NS_IMPL_RELEASE(nsPipeInputStream);
+
+NS_INTERFACE_TABLE_HEAD(nsPipeInputStream)
+  NS_INTERFACE_TABLE_BEGIN
+    NS_INTERFACE_TABLE_ENTRY(nsPipeInputStream, nsIAsyncInputStream)
+    NS_INTERFACE_TABLE_ENTRY(nsPipeInputStream, nsISeekableStream)
+    NS_INTERFACE_TABLE_ENTRY(nsPipeInputStream, nsISearchableInputStream)
+    NS_INTERFACE_TABLE_ENTRY(nsPipeInputStream, nsICloneableInputStream)
+    NS_INTERFACE_TABLE_ENTRY(nsPipeInputStream, nsIBufferedInputStream)
+    NS_INTERFACE_TABLE_ENTRY(nsPipeInputStream, nsIClassInfo)
+    NS_INTERFACE_TABLE_ENTRY_AMBIGUOUS(nsPipeInputStream, nsIInputStream,
+                                       nsIAsyncInputStream)
+    NS_INTERFACE_TABLE_ENTRY_AMBIGUOUS(nsPipeInputStream, nsISupports,
+                                       nsIAsyncInputStream)
+  NS_INTERFACE_TABLE_END
+NS_INTERFACE_TABLE_TAIL
+
+NS_IMPL_CI_INTERFACE_GETTER(nsPipeInputStream,
+                            nsIInputStream,
+                            nsIAsyncInputStream,
+                            nsISeekableStream,
+                            nsISearchableInputStream,
+                            nsICloneableInputStream,
+                            nsIBufferedInputStream)
+
+NS_IMPL_THREADSAFE_CI(nsPipeInputStream)
+
+NS_IMETHODIMP
+nsPipeInputStream::Init(nsIInputStream*, uint32_t)
+{
+  MOZ_CRASH("nsPipeInputStream should never be initialized with "
+            "nsIBufferedInputStream::Init!\n");
+}
+
+uint32_t
+nsPipeInputStream::Available()
+{
+  mPipe->mReentrantMonitor.AssertCurrentThreadIn();
+  return mReadState.mAvailable;
+}
+
+nsresult
+nsPipeInputStream::Wait()
+{
+  NS_ASSERTION(mBlocking, "wait on non-blocking pipe input stream");
+
+  ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+
+  while (NS_SUCCEEDED(Status(mon)) && (mReadState.mAvailable == 0)) {
+    LOG(("III pipe input: waiting for data\n"));
+
+    mBlocked = true;
+    mon.Wait();
+    mBlocked = false;
+
+    LOG(("III pipe input: woke up [status=%x available=%u]\n",
+         Status(mon), mReadState.mAvailable));
+  }
+
+  return Status(mon) == NS_BASE_STREAM_CLOSED ? NS_OK : Status(mon);
+}
+
+MonitorAction
+nsPipeInputStream::OnInputReadable(uint32_t aBytesWritten,
+                                   nsPipeEvents& aEvents,
+                                   const ReentrantMonitorAutoEnter& ev)
+{
+  MonitorAction result = DoNotNotifyMonitor;
+
+  mPipe->mReentrantMonitor.AssertCurrentThreadIn();
+  mReadState.mAvailable += aBytesWritten;
+
+  if (mCallback && !(mCallbackFlags & WAIT_CLOSURE_ONLY)) {
+    aEvents.NotifyInputReady(this, mCallback);
+    mCallback = nullptr;
+    mCallbackFlags = 0;
+  } else if (mBlocked) {
+    result = NotifyMonitor;
+  }
+
+  return result;
+}
+
+MonitorAction
+nsPipeInputStream::OnInputException(nsresult aReason, nsPipeEvents& aEvents,
+                                    const ReentrantMonitorAutoEnter& ev)
+{
+  LOG(("nsPipeInputStream::OnInputException [this=%x reason=%x]\n",
+       this, aReason));
+
+  MonitorAction result = DoNotNotifyMonitor;
+
+  NS_ASSERTION(NS_FAILED(aReason), "huh? successful exception");
+
+  if (NS_SUCCEEDED(mInputStatus)) {
+    mInputStatus = aReason;
+  }
+
+  // force count of available bytes to zero.
+  mPipe->DrainInputStream(mReadState, aEvents);
+
+  if (mCallback) {
+    aEvents.NotifyInputReady(this, mCallback);
+    mCallback = nullptr;
+    mCallbackFlags = 0;
+  } else if (mBlocked) {
+    result = NotifyMonitor;
+  }
+
+  return result;
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::CloseWithStatus(nsresult aReason)
+{
+  LOG(("III CloseWithStatus [this=%x reason=%x]\n", this, aReason));
+
+  ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+
+  if (NS_FAILED(mInputStatus)) {
+    return NS_OK;
+  }
+
+  if (NS_SUCCEEDED(aReason)) {
+    aReason = NS_BASE_STREAM_CLOSED;
+  }
+
+  mPipe->OnInputStreamException(this, aReason);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::Close()
+{
+  return CloseWithStatus(NS_BASE_STREAM_CLOSED);
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::Available(uint64_t* aResult)
+{
+  // nsPipeInputStream supports under 4GB stream only
+  ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+
+  // return error if closed
+  if (!mReadState.mAvailable && NS_FAILED(Status(mon))) {
+    return Status(mon);
+  }
+
+  *aResult = (uint64_t)mReadState.mAvailable;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::ReadSegments(nsWriteSegmentFun aWriter,
+                                void* aClosure,
+                                uint32_t aCount,
+                                uint32_t* aReadCount)
+{
+  LOG(("III ReadSegments [this=%x count=%u]\n", this, aCount));
+
+  nsresult rv = NS_OK;
+
+  *aReadCount = 0;
+  while (aCount) {
+    AutoReadSegment segment(mPipe, mReadState, aCount);
+    rv = segment.Status();
+    if (NS_FAILED(rv)) {
+      // ignore this error if we've already read something.
+      if (*aReadCount > 0) {
+        rv = NS_OK;
+        break;
+      }
+      if (rv == NS_BASE_STREAM_WOULD_BLOCK) {
+        // pipe is empty
+        if (!mBlocking) {
+          break;
+        }
+        // wait for some data to be written to the pipe
+        rv = Wait();
+        if (NS_SUCCEEDED(rv)) {
+          continue;
+        }
+      }
+      // ignore this error, just return.
+      if (rv == NS_BASE_STREAM_CLOSED) {
+        rv = NS_OK;
+        break;
+      }
+      mPipe->OnInputStreamException(this, rv);
+      break;
+    }
+
+    uint32_t writeCount;
+    while (segment.Length()) {
+      writeCount = 0;
+
+      rv = aWriter(static_cast<nsIAsyncInputStream*>(this), aClosure,
+                   segment.Data(), *aReadCount, segment.Length(), &writeCount);
+
+      if (NS_FAILED(rv) || writeCount == 0) {
+        aCount = 0;
+        // any errors returned from the writer end here: do not
+        // propagate to the caller of ReadSegments.
+        rv = NS_OK;
+        break;
+      }
+
+      NS_ASSERTION(writeCount <= segment.Length(), "wrote more than expected");
+      segment.Advance(writeCount);
+      aCount -= writeCount;
+      *aReadCount += writeCount;
+      mLogicalOffset += writeCount;
+    }
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::Read(char* aToBuf, uint32_t aBufLen, uint32_t* aReadCount)
+{
+  return ReadSegments(NS_CopySegmentToBuffer, aToBuf, aBufLen, aReadCount);
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::IsNonBlocking(bool* aNonBlocking)
+{
+  *aNonBlocking = !mBlocking;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::AsyncWait(nsIInputStreamCallback* aCallback,
+                             uint32_t aFlags,
+                             uint32_t aRequestedCount,
+                             nsIEventTarget* aTarget)
+{
+  LOG(("III AsyncWait [this=%x]\n", this));
+
+  nsPipeEvents pipeEvents;
+  {
+    ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+
+    // replace a pending callback
+    mCallback = nullptr;
+    mCallbackFlags = 0;
+
+    if (!aCallback) {
+      return NS_OK;
+    }
+
+    nsCOMPtr<nsIInputStreamCallback> proxy;
+    if (aTarget) {
+      proxy = NS_NewInputStreamReadyEvent(aCallback, aTarget);
+      aCallback = proxy;
+    }
+
+    if (NS_FAILED(Status(mon)) ||
+       (mReadState.mAvailable && !(aFlags & WAIT_CLOSURE_ONLY))) {
+      // stream is already closed or readable; post event.
+      pipeEvents.NotifyInputReady(this, aCallback);
+    } else {
+      // queue up callback object to be notified when data becomes available
+      mCallback = aCallback;
+      mCallbackFlags = aFlags;
+    }
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::Seek(int32_t aWhence, int64_t aOffset)
+{
+  NS_NOTREACHED("nsPipeInputStream::Seek");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::Tell(int64_t* aOffset)
+{
+  ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+
+  // return error if closed
+  if (!mReadState.mAvailable && NS_FAILED(Status(mon))) {
+    return Status(mon);
+  }
+
+  *aOffset = mLogicalOffset;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::SetEOF()
+{
+  NS_NOTREACHED("nsPipeInputStream::SetEOF");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+static bool strings_equal(bool aIgnoreCase,
+                          const char* aS1, const char* aS2, uint32_t aLen)
+{
+  return aIgnoreCase
+    ? !nsCRT::strncasecmp(aS1, aS2, aLen) : !nsCRT::strncmp(aS1, aS2, aLen);
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::Search(const char* aForString,
+                          bool aIgnoreCase,
+                          bool* aFound,
+                          uint32_t* aOffsetSearchedTo)
+{
+  LOG(("III Search [for=%s ic=%u]\n", aForString, aIgnoreCase));
+
+  ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+
+  char* cursor1;
+  char* limit1;
+  uint32_t index = 0, offset = 0;
+  uint32_t strLen = strlen(aForString);
+
+  mPipe->PeekSegment(mReadState, 0, cursor1, limit1);
+  if (cursor1 == limit1) {
+    *aFound = false;
+    *aOffsetSearchedTo = 0;
+    LOG(("  result [aFound=%u offset=%u]\n", *aFound, *aOffsetSearchedTo));
+    return NS_OK;
+  }
+
+  while (true) {
+    uint32_t i, len1 = limit1 - cursor1;
+
+    // check if the string is in the buffer segment
+    for (i = 0; i < len1 - strLen + 1; i++) {
+      if (strings_equal(aIgnoreCase, &cursor1[i], aForString, strLen)) {
+        *aFound = true;
+        *aOffsetSearchedTo = offset + i;
+        LOG(("  result [aFound=%u offset=%u]\n", *aFound, *aOffsetSearchedTo));
+        return NS_OK;
+      }
+    }
+
+    // get the next segment
+    char* cursor2;
+    char* limit2;
+    uint32_t len2;
+
+    index++;
+    offset += len1;
+
+    mPipe->PeekSegment(mReadState, index, cursor2, limit2);
+    if (cursor2 == limit2) {
+      *aFound = false;
+      *aOffsetSearchedTo = offset - strLen + 1;
+      LOG(("  result [aFound=%u offset=%u]\n", *aFound, *aOffsetSearchedTo));
+      return NS_OK;
+    }
+    len2 = limit2 - cursor2;
+
+    // check if the string is straddling the next buffer segment
+    uint32_t lim = XPCOM_MIN(strLen, len2 + 1);
+    for (i = 0; i < lim; ++i) {
+      uint32_t strPart1Len = strLen - i - 1;
+      uint32_t strPart2Len = strLen - strPart1Len;
+      const char* strPart2 = &aForString[strLen - strPart2Len];
+      uint32_t bufSeg1Offset = len1 - strPart1Len;
+      if (strings_equal(aIgnoreCase, &cursor1[bufSeg1Offset], aForString, strPart1Len) &&
+          strings_equal(aIgnoreCase, cursor2, strPart2, strPart2Len)) {
+        *aFound = true;
+        *aOffsetSearchedTo = offset - strPart1Len;
+        LOG(("  result [aFound=%u offset=%u]\n", *aFound, *aOffsetSearchedTo));
+        return NS_OK;
+      }
+    }
+
+    // finally continue with the next buffer
+    cursor1 = cursor2;
+    limit1 = limit2;
+  }
+
+  NS_NOTREACHED("can't get here");
+  return NS_ERROR_UNEXPECTED;    // keep compiler happy
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::GetCloneable(bool* aCloneableOut)
+{
+  *aCloneableOut = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeInputStream::Clone(nsIInputStream** aCloneOut)
+{
+  return mPipe->CloneInputStream(this, aCloneOut);
+}
+
+nsresult
+nsPipeInputStream::Status(const ReentrantMonitorAutoEnter& ev) const
+{
+  if (NS_FAILED(mInputStatus)) {
+    return mInputStatus;
+  }
+
+  if (mReadState.mAvailable) {
+    // Still something to read and this input stream state is OK.
+    return NS_OK;
+  }
+
+  // Nothing to read, just fall through to the pipe's state that
+  // may reflect state of its output stream side (already closed).
+  return mPipe->mStatus;
+}
+
+nsresult
+nsPipeInputStream::Status() const
+{
+  ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+  return Status(mon);
+}
+
+nsPipeInputStream::~nsPipeInputStream()
+{
+  Close();
+}
+
+//-----------------------------------------------------------------------------
+// nsPipeOutputStream methods:
+//-----------------------------------------------------------------------------
+
+NS_IMPL_QUERY_INTERFACE(nsPipeOutputStream,
+                        nsIOutputStream,
+                        nsIAsyncOutputStream,
+                        nsIClassInfo)
+
+NS_IMPL_CI_INTERFACE_GETTER(nsPipeOutputStream,
+                            nsIOutputStream,
+                            nsIAsyncOutputStream)
+
+NS_IMPL_THREADSAFE_CI(nsPipeOutputStream)
+
+nsresult
+nsPipeOutputStream::Wait()
+{
+  NS_ASSERTION(mBlocking, "wait on non-blocking pipe output stream");
+
+  ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+
+  if (NS_SUCCEEDED(mPipe->mStatus) && !mWritable) {
+    LOG(("OOO pipe output: waiting for space\n"));
+    mBlocked = true;
+    mon.Wait();
+    mBlocked = false;
+    LOG(("OOO pipe output: woke up [pipe-status=%x writable=%u]\n",
+         mPipe->mStatus, mWritable));
+  }
+
+  return mPipe->mStatus == NS_BASE_STREAM_CLOSED ? NS_OK : mPipe->mStatus;
+}
+
+MonitorAction
+nsPipeOutputStream::OnOutputWritable(nsPipeEvents& aEvents)
+{
+  MonitorAction result = DoNotNotifyMonitor;
+
+  mWritable = true;
+
+  if (mCallback && !(mCallbackFlags & WAIT_CLOSURE_ONLY)) {
+    aEvents.NotifyOutputReady(this, mCallback);
+    mCallback = nullptr;
+    mCallbackFlags = 0;
+  } else if (mBlocked) {
+    result = NotifyMonitor;
+  }
+
+  return result;
+}
+
+MonitorAction
+nsPipeOutputStream::OnOutputException(nsresult aReason, nsPipeEvents& aEvents)
+{
+  LOG(("nsPipeOutputStream::OnOutputException [this=%x reason=%x]\n",
+       this, aReason));
+
+  MonitorAction result = DoNotNotifyMonitor;
+
+  NS_ASSERTION(NS_FAILED(aReason), "huh? successful exception");
+  mWritable = false;
+
+  if (mCallback) {
+    aEvents.NotifyOutputReady(this, mCallback);
+    mCallback = nullptr;
+    mCallbackFlags = 0;
+  } else if (mBlocked) {
+    result = NotifyMonitor;
+  }
+
+  return result;
+}
+
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsPipeOutputStream::AddRef()
+{
+  ++mWriterRefCnt;
+  return mPipe->AddRef();
+}
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsPipeOutputStream::Release()
+{
+  if (--mWriterRefCnt == 0) {
+    Close();
+  }
+  return mPipe->Release();
+}
+
+NS_IMETHODIMP
+nsPipeOutputStream::CloseWithStatus(nsresult aReason)
+{
+  LOG(("OOO CloseWithStatus [this=%x reason=%x]\n", this, aReason));
+
+  if (NS_SUCCEEDED(aReason)) {
+    aReason = NS_BASE_STREAM_CLOSED;
+  }
+
+  // input stream may remain open
+  mPipe->OnPipeException(aReason, true);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeOutputStream::Close()
+{
+  return CloseWithStatus(NS_BASE_STREAM_CLOSED);
+}
+
+NS_IMETHODIMP
+nsPipeOutputStream::WriteSegments(nsReadSegmentFun aReader,
+                                  void* aClosure,
+                                  uint32_t aCount,
+                                  uint32_t* aWriteCount)
+{
+  LOG(("OOO WriteSegments [this=%x count=%u]\n", this, aCount));
+
+  nsresult rv = NS_OK;
+
+  char* segment;
+  uint32_t segmentLen;
+
+  *aWriteCount = 0;
+  while (aCount) {
+    rv = mPipe->GetWriteSegment(segment, segmentLen);
+    if (NS_FAILED(rv)) {
+      if (rv == NS_BASE_STREAM_WOULD_BLOCK) {
+        // pipe is full
+        if (!mBlocking) {
+          // ignore this error if we've already written something
+          if (*aWriteCount > 0) {
+            rv = NS_OK;
+          }
+          break;
+        }
+        // wait for the pipe to have an empty segment.
+        rv = Wait();
+        if (NS_SUCCEEDED(rv)) {
+          continue;
+        }
+      }
+      mPipe->OnPipeException(rv);
+      break;
+    }
+
+    // write no more than aCount
+    if (segmentLen > aCount) {
+      segmentLen = aCount;
+    }
+
+    uint32_t readCount, originalLen = segmentLen;
+    while (segmentLen) {
+      readCount = 0;
+
+      rv = aReader(this, aClosure, segment, *aWriteCount, segmentLen, &readCount);
+
+      if (NS_FAILED(rv) || readCount == 0) {
+        aCount = 0;
+        // any errors returned from the aReader end here: do not
+        // propagate to the caller of WriteSegments.
+        rv = NS_OK;
+        break;
+      }
+
+      NS_ASSERTION(readCount <= segmentLen, "read more than expected");
+      segment += readCount;
+      segmentLen -= readCount;
+      aCount -= readCount;
+      *aWriteCount += readCount;
+      mLogicalOffset += readCount;
+    }
+
+    if (segmentLen < originalLen) {
+      mPipe->AdvanceWriteCursor(originalLen - segmentLen);
+    }
+  }
+
+  return rv;
+}
+
+static nsresult
+nsReadFromRawBuffer(nsIOutputStream* aOutStr,
+                    void* aClosure,
+                    char* aToRawSegment,
+                    uint32_t aOffset,
+                    uint32_t aCount,
+                    uint32_t* aReadCount)
+{
+  const char* fromBuf = (const char*)aClosure;
+  memcpy(aToRawSegment, &fromBuf[aOffset], aCount);
+  *aReadCount = aCount;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeOutputStream::Write(const char* aFromBuf,
+                          uint32_t aBufLen,
+                          uint32_t* aWriteCount)
+{
+  return WriteSegments(nsReadFromRawBuffer, (void*)aFromBuf, aBufLen, aWriteCount);
+}
+
+NS_IMETHODIMP
+nsPipeOutputStream::Flush(void)
+{
+  // nothing to do
+  return NS_OK;
+}
+
+static nsresult
+nsReadFromInputStream(nsIOutputStream* aOutStr,
+                      void* aClosure,
+                      char* aToRawSegment,
+                      uint32_t aOffset,
+                      uint32_t aCount,
+                      uint32_t* aReadCount)
+{
+  nsIInputStream* fromStream = (nsIInputStream*)aClosure;
+  return fromStream->Read(aToRawSegment, aCount, aReadCount);
+}
+
+NS_IMETHODIMP
+nsPipeOutputStream::WriteFrom(nsIInputStream* aFromStream,
+                              uint32_t aCount,
+                              uint32_t* aWriteCount)
+{
+  return WriteSegments(nsReadFromInputStream, aFromStream, aCount, aWriteCount);
+}
+
+NS_IMETHODIMP
+nsPipeOutputStream::IsNonBlocking(bool* aNonBlocking)
+{
+  *aNonBlocking = !mBlocking;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPipeOutputStream::AsyncWait(nsIOutputStreamCallback* aCallback,
+                              uint32_t aFlags,
+                              uint32_t aRequestedCount,
+                              nsIEventTarget* aTarget)
+{
+  LOG(("OOO AsyncWait [this=%x]\n", this));
+
+  nsPipeEvents pipeEvents;
+  {
+    ReentrantMonitorAutoEnter mon(mPipe->mReentrantMonitor);
+
+    // replace a pending callback
+    mCallback = nullptr;
+    mCallbackFlags = 0;
+
+    if (!aCallback) {
+      return NS_OK;
+    }
+
+    nsCOMPtr<nsIOutputStreamCallback> proxy;
+    if (aTarget) {
+      proxy = NS_NewOutputStreamReadyEvent(aCallback, aTarget);
+      aCallback = proxy;
+    }
+
+    if (NS_FAILED(mPipe->mStatus) ||
+        (mWritable && !(aFlags & WAIT_CLOSURE_ONLY))) {
+      // stream is already closed or writable; post event.
+      pipeEvents.NotifyOutputReady(this, aCallback);
+    } else {
+      // queue up callback object to be notified when data becomes available
+      mCallback = aCallback;
+      mCallbackFlags = aFlags;
+    }
+  }
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+nsresult
+NS_NewPipe(nsIInputStream** aPipeIn,
+           nsIOutputStream** aPipeOut,
+           uint32_t aSegmentSize,
+           uint32_t aMaxSize,
+           bool aNonBlockingInput,
+           bool aNonBlockingOutput)
+{
+  if (aSegmentSize == 0) {
+    aSegmentSize = DEFAULT_SEGMENT_SIZE;
+  }
+
+  // Handle aMaxSize of UINT32_MAX as a special case
+  uint32_t segmentCount;
+  if (aMaxSize == UINT32_MAX) {
+    segmentCount = UINT32_MAX;
+  } else {
+    segmentCount = aMaxSize / aSegmentSize;
+  }
+
+  nsIAsyncInputStream* in;
+  nsIAsyncOutputStream* out;
+  nsresult rv = NS_NewPipe2(&in, &out, aNonBlockingInput, aNonBlockingOutput,
+                            aSegmentSize, segmentCount);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  *aPipeIn = in;
+  *aPipeOut = out;
+  return NS_OK;
+}
+
+nsresult
+NS_NewPipe2(nsIAsyncInputStream** aPipeIn,
+            nsIAsyncOutputStream** aPipeOut,
+            bool aNonBlockingInput,
+            bool aNonBlockingOutput,
+            uint32_t aSegmentSize,
+            uint32_t aSegmentCount)
+{
+  nsPipe* pipe = new nsPipe();
+  nsresult rv = pipe->Init(aNonBlockingInput,
+                           aNonBlockingOutput,
+                           aSegmentSize,
+                           aSegmentCount);
+  if (NS_FAILED(rv)) {
+    NS_ADDREF(pipe);
+    NS_RELEASE(pipe);
+    return rv;
+  }
+
+  // These always succeed because the pipe is initialized above.
+  MOZ_ALWAYS_SUCCEEDS(pipe->GetInputStream(aPipeIn));
+  MOZ_ALWAYS_SUCCEEDS(pipe->GetOutputStream(aPipeOut));
+  return NS_OK;
+}
+
+nsresult
+nsPipeConstructor(nsISupports* aOuter, REFNSIID aIID, void** aResult)
+{
+  if (aOuter) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+  nsPipe* pipe = new nsPipe();
+  NS_ADDREF(pipe);
+  nsresult rv = pipe->QueryInterface(aIID, aResult);
+  NS_RELEASE(pipe);
+  return rv;
+}
+
+////////////////////////////////////////////////////////////////////////////////
diff --git a/xpcom/io/nsScriptableBase64Encoder.cpp b/xpcom/io/nsScriptableBase64Encoder.cpp
new file mode 100644
index 000000000..a8ffce8cd
--- /dev/null
+++ b/xpcom/io/nsScriptableBase64Encoder.cpp
@@ -0,0 +1,28 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsScriptableBase64Encoder.h"
+#include "mozilla/Base64.h"
+
+using namespace mozilla;
+
+NS_IMPL_ISUPPORTS(nsScriptableBase64Encoder, nsIScriptableBase64Encoder)
+
+NS_IMETHODIMP
+nsScriptableBase64Encoder::EncodeToCString(nsIInputStream* aStream,
+                                           uint32_t aLength,
+                                           nsACString& aResult)
+{
+  return Base64EncodeInputStream(aStream, aResult, aLength);
+}
+
+NS_IMETHODIMP
+nsScriptableBase64Encoder::EncodeToString(nsIInputStream* aStream,
+                                          uint32_t aLength,
+                                          nsAString& aResult)
+{
+  return Base64EncodeInputStream(aStream, aResult, aLength);
+}
diff --git a/xpcom/io/nsScriptableBase64Encoder.h b/xpcom/io/nsScriptableBase64Encoder.h
new file mode 100644
index 000000000..d9121e5de
--- /dev/null
+++ b/xpcom/io/nsScriptableBase64Encoder.h
@@ -0,0 +1,30 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsScriptableBase64Encoder_h__
+#define nsScriptableBase64Encoder_h__
+
+#include "nsIScriptableBase64Encoder.h"
+#include "mozilla/Attributes.h"
+
+#define NS_SCRIPTABLEBASE64ENCODER_CID                 \
+  {0xaaf68860, 0xf849, 0x40ee,                         \
+   {0xbb, 0x7a, 0xb2, 0x29, 0xbc, 0xe0, 0x36, 0xa3} }
+#define NS_SCRIPTABLEBASE64ENCODER_CONTRACTID \
+  "@mozilla.org/scriptablebase64encoder;1"
+
+class nsScriptableBase64Encoder final : public nsIScriptableBase64Encoder
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISCRIPTABLEBASE64ENCODER
+private:
+  ~nsScriptableBase64Encoder()
+  {
+  }
+};
+
+#endif
diff --git a/xpcom/io/nsScriptableInputStream.cpp b/xpcom/io/nsScriptableInputStream.cpp
new file mode 100644
index 000000000..6f8022238
--- /dev/null
+++ b/xpcom/io/nsScriptableInputStream.cpp
@@ -0,0 +1,134 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsScriptableInputStream.h"
+#include "nsMemory.h"
+#include "nsString.h"
+
+NS_IMPL_ISUPPORTS(nsScriptableInputStream, nsIScriptableInputStream)
+
+// nsIScriptableInputStream methods
+NS_IMETHODIMP
+nsScriptableInputStream::Close()
+{
+  if (!mInputStream) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return mInputStream->Close();
+}
+
+NS_IMETHODIMP
+nsScriptableInputStream::Init(nsIInputStream* aInputStream)
+{
+  if (!aInputStream) {
+    return NS_ERROR_NULL_POINTER;
+  }
+  mInputStream = aInputStream;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsScriptableInputStream::Available(uint64_t* aResult)
+{
+  if (!mInputStream) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return mInputStream->Available(aResult);
+}
+
+NS_IMETHODIMP
+nsScriptableInputStream::Read(uint32_t aCount, char** aResult)
+{
+  nsresult rv = NS_OK;
+  uint64_t count64 = 0;
+  char* buffer = nullptr;
+
+  if (!mInputStream) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  rv = mInputStream->Available(&count64);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // bug716556 - Ensure count+1 doesn't overflow
+  uint32_t count =
+    XPCOM_MIN((uint32_t)XPCOM_MIN<uint64_t>(count64, aCount), UINT32_MAX - 1);
+  buffer = (char*)malloc(count + 1);  // make room for '\0'
+  if (!buffer) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  rv = ReadHelper(buffer, count);
+  if (NS_FAILED(rv)) {
+    free(buffer);
+    return rv;
+  }
+
+  buffer[count] = '\0';
+  *aResult = buffer;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsScriptableInputStream::ReadBytes(uint32_t aCount, nsACString& aResult)
+{
+  if (!mInputStream) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  if (!aResult.SetLength(aCount, fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  MOZ_ASSERT(aResult.Length() == aCount);
+  char* ptr = aResult.BeginWriting();
+  nsresult rv = ReadHelper(ptr, aCount);
+  if (NS_FAILED(rv)) {
+    aResult.Truncate();
+  }
+  return rv;
+}
+
+nsresult
+nsScriptableInputStream::ReadHelper(char* aBuffer, uint32_t aCount)
+{
+  uint32_t totalBytesRead = 0;
+  while (1) {
+    uint32_t bytesRead;
+    nsresult rv = mInputStream->Read(aBuffer + totalBytesRead,
+                                     aCount - totalBytesRead,
+                                     &bytesRead);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    totalBytesRead += bytesRead;
+    if (totalBytesRead == aCount) {
+      break;
+    }
+
+    // If we have read zero bytes, we have hit EOF.
+    if (bytesRead == 0) {
+      return NS_ERROR_FAILURE;
+    }
+
+  }
+  return NS_OK;
+}
+
+nsresult
+nsScriptableInputStream::Create(nsISupports* aOuter, REFNSIID aIID,
+                                void** aResult)
+{
+  if (aOuter) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+
+  RefPtr<nsScriptableInputStream> sis = new nsScriptableInputStream();
+  return sis->QueryInterface(aIID, aResult);
+}
diff --git a/xpcom/io/nsScriptableInputStream.h b/xpcom/io/nsScriptableInputStream.h
new file mode 100644
index 000000000..a84facd94
--- /dev/null
+++ b/xpcom/io/nsScriptableInputStream.h
@@ -0,0 +1,47 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef ___nsscriptableinputstream___h_
+#define ___nsscriptableinputstream___h_
+
+#include "nsIScriptableInputStream.h"
+#include "nsIInputStream.h"
+#include "nsCOMPtr.h"
+#include "mozilla/Attributes.h"
+
+#define NS_SCRIPTABLEINPUTSTREAM_CID        \
+{ 0x7225c040, 0xa9bf, 0x11d3, { 0xa1, 0x97, 0x0, 0x50, 0x4, 0x1c, 0xaf, 0x44 } }
+
+#define NS_SCRIPTABLEINPUTSTREAM_CONTRACTID "@mozilla.org/scriptableinputstream;1"
+
+class nsScriptableInputStream final : public nsIScriptableInputStream
+{
+public:
+  // nsISupports methods
+  NS_DECL_ISUPPORTS
+
+  // nsIScriptableInputStream methods
+  NS_DECL_NSISCRIPTABLEINPUTSTREAM
+
+  // nsScriptableInputStream methods
+  nsScriptableInputStream()
+  {
+  }
+
+  static nsresult
+  Create(nsISupports* aOuter, REFNSIID aIID, void** aResult);
+
+private:
+  ~nsScriptableInputStream()
+  {
+  }
+
+  nsresult ReadHelper(char* aBuffer, uint32_t aCount);
+
+  nsCOMPtr<nsIInputStream> mInputStream;
+};
+
+#endif // ___nsscriptableinputstream___h_
diff --git a/xpcom/io/nsSegmentedBuffer.cpp b/xpcom/io/nsSegmentedBuffer.cpp
new file mode 100644
index 000000000..ab42a73c7
--- /dev/null
+++ b/xpcom/io/nsSegmentedBuffer.cpp
@@ -0,0 +1,169 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsSegmentedBuffer.h"
+#include "nsMemory.h"
+
+nsresult
+nsSegmentedBuffer::Init(uint32_t aSegmentSize, uint32_t aMaxSize)
+{
+  if (mSegmentArrayCount != 0) {
+    return NS_ERROR_FAILURE;  // initialized more than once
+  }
+  mSegmentSize = aSegmentSize;
+  mMaxSize = aMaxSize;
+#if 0 // testing...
+  mSegmentArrayCount = 2;
+#else
+  mSegmentArrayCount = NS_SEGMENTARRAY_INITIAL_COUNT;
+#endif
+  return NS_OK;
+}
+
+char*
+nsSegmentedBuffer::AppendNewSegment()
+{
+  if (GetSize() >= mMaxSize) {
+    return nullptr;
+  }
+
+  if (!mSegmentArray) {
+    uint32_t bytes = mSegmentArrayCount * sizeof(char*);
+    mSegmentArray = (char**)moz_xmalloc(bytes);
+    if (!mSegmentArray) {
+      return nullptr;
+    }
+    memset(mSegmentArray, 0, bytes);
+  }
+
+  if (IsFull()) {
+    uint32_t newArraySize = mSegmentArrayCount * 2;
+    uint32_t bytes = newArraySize * sizeof(char*);
+    char** newSegArray = (char**)moz_xrealloc(mSegmentArray, bytes);
+    if (!newSegArray) {
+      return nullptr;
+    }
+    mSegmentArray = newSegArray;
+    // copy wrapped content to new extension
+    if (mFirstSegmentIndex > mLastSegmentIndex) {
+      // deal with wrap around case
+      memcpy(&mSegmentArray[mSegmentArrayCount],
+             mSegmentArray,
+             mLastSegmentIndex * sizeof(char*));
+      memset(mSegmentArray, 0, mLastSegmentIndex * sizeof(char*));
+      mLastSegmentIndex += mSegmentArrayCount;
+      memset(&mSegmentArray[mLastSegmentIndex], 0,
+             (newArraySize - mLastSegmentIndex) * sizeof(char*));
+    } else {
+      memset(&mSegmentArray[mLastSegmentIndex], 0,
+             (newArraySize - mLastSegmentIndex) * sizeof(char*));
+    }
+    mSegmentArrayCount = newArraySize;
+  }
+
+  char* seg = (char*)malloc(mSegmentSize);
+  if (!seg) {
+    return nullptr;
+  }
+  mSegmentArray[mLastSegmentIndex] = seg;
+  mLastSegmentIndex = ModSegArraySize(mLastSegmentIndex + 1);
+  return seg;
+}
+
+bool
+nsSegmentedBuffer::DeleteFirstSegment()
+{
+  NS_ASSERTION(mSegmentArray[mFirstSegmentIndex] != nullptr, "deleting bad segment");
+  free(mSegmentArray[mFirstSegmentIndex]);
+  mSegmentArray[mFirstSegmentIndex] = nullptr;
+  int32_t last = ModSegArraySize(mLastSegmentIndex - 1);
+  if (mFirstSegmentIndex == last) {
+    mLastSegmentIndex = last;
+    return true;
+  } else {
+    mFirstSegmentIndex = ModSegArraySize(mFirstSegmentIndex + 1);
+    return false;
+  }
+}
+
+bool
+nsSegmentedBuffer::DeleteLastSegment()
+{
+  int32_t last = ModSegArraySize(mLastSegmentIndex - 1);
+  NS_ASSERTION(mSegmentArray[last] != nullptr, "deleting bad segment");
+  free(mSegmentArray[last]);
+  mSegmentArray[last] = nullptr;
+  mLastSegmentIndex = last;
+  return (bool)(mLastSegmentIndex == mFirstSegmentIndex);
+}
+
+bool
+nsSegmentedBuffer::ReallocLastSegment(size_t aNewSize)
+{
+  int32_t last = ModSegArraySize(mLastSegmentIndex - 1);
+  NS_ASSERTION(mSegmentArray[last] != nullptr, "realloc'ing bad segment");
+  char* newSegment = (char*)realloc(mSegmentArray[last], aNewSize);
+  if (newSegment) {
+    mSegmentArray[last] = newSegment;
+    return true;
+  }
+  return false;
+}
+
+void
+nsSegmentedBuffer::Empty()
+{
+  if (mSegmentArray) {
+    for (uint32_t i = 0; i < mSegmentArrayCount; i++) {
+      if (mSegmentArray[i]) {
+        free(mSegmentArray[i]);
+      }
+    }
+    free(mSegmentArray);
+    mSegmentArray = nullptr;
+  }
+  mSegmentArrayCount = NS_SEGMENTARRAY_INITIAL_COUNT;
+  mFirstSegmentIndex = mLastSegmentIndex = 0;
+}
+
+#if 0
+void
+TestSegmentedBuffer()
+{
+  nsSegmentedBuffer* buf = new nsSegmentedBuffer();
+  NS_ASSERTION(buf, "out of memory");
+  buf->Init(4, 16);
+  char* seg;
+  bool empty;
+  seg = buf->AppendNewSegment();
+  NS_ASSERTION(seg, "AppendNewSegment failed");
+  seg = buf->AppendNewSegment();
+  NS_ASSERTION(seg, "AppendNewSegment failed");
+  seg = buf->AppendNewSegment();
+  NS_ASSERTION(seg, "AppendNewSegment failed");
+  empty = buf->DeleteFirstSegment();
+  NS_ASSERTION(!empty, "DeleteFirstSegment failed");
+  empty = buf->DeleteFirstSegment();
+  NS_ASSERTION(!empty, "DeleteFirstSegment failed");
+  seg = buf->AppendNewSegment();
+  NS_ASSERTION(seg, "AppendNewSegment failed");
+  seg = buf->AppendNewSegment();
+  NS_ASSERTION(seg, "AppendNewSegment failed");
+  seg = buf->AppendNewSegment();
+  NS_ASSERTION(seg, "AppendNewSegment failed");
+  empty = buf->DeleteFirstSegment();
+  NS_ASSERTION(!empty, "DeleteFirstSegment failed");
+  empty = buf->DeleteFirstSegment();
+  NS_ASSERTION(!empty, "DeleteFirstSegment failed");
+  empty = buf->DeleteFirstSegment();
+  NS_ASSERTION(!empty, "DeleteFirstSegment failed");
+  empty = buf->DeleteFirstSegment();
+  NS_ASSERTION(empty, "DeleteFirstSegment failed");
+  delete buf;
+}
+#endif
+
+////////////////////////////////////////////////////////////////////////////////
diff --git a/xpcom/io/nsSegmentedBuffer.h b/xpcom/io/nsSegmentedBuffer.h
new file mode 100644
index 000000000..37b3a8e4f
--- /dev/null
+++ b/xpcom/io/nsSegmentedBuffer.h
@@ -0,0 +1,109 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSegmentedBuffer_h__
+#define nsSegmentedBuffer_h__
+
+#include "nsIMemory.h"
+
+class nsSegmentedBuffer
+{
+public:
+  nsSegmentedBuffer()
+    : mSegmentSize(0)
+    , mMaxSize(0)
+    , mSegmentArray(nullptr)
+    , mSegmentArrayCount(0)
+    , mFirstSegmentIndex(0)
+    , mLastSegmentIndex(0)
+  {
+  }
+
+  ~nsSegmentedBuffer()
+  {
+    Empty();
+  }
+
+
+  nsresult Init(uint32_t aSegmentSize, uint32_t aMaxSize);
+
+  char* AppendNewSegment();   // pushes at end
+
+  // returns true if no more segments remain:
+  bool DeleteFirstSegment();  // pops from beginning
+
+  // returns true if no more segments remain:
+  bool DeleteLastSegment();  // pops from beginning
+
+  // Call Realloc() on last segment.  This is used to reduce memory
+  // consumption when data is not an exact multiple of segment size.
+  bool ReallocLastSegment(size_t aNewSize);
+
+  void Empty();               // frees all segments
+
+  inline uint32_t GetSegmentCount()
+  {
+    if (mFirstSegmentIndex <= mLastSegmentIndex) {
+      return mLastSegmentIndex - mFirstSegmentIndex;
+    } else {
+      return mSegmentArrayCount + mLastSegmentIndex - mFirstSegmentIndex;
+    }
+  }
+
+  inline uint32_t GetSegmentSize()
+  {
+    return mSegmentSize;
+  }
+  inline uint32_t GetMaxSize()
+  {
+    return mMaxSize;
+  }
+  inline uint32_t GetSize()
+  {
+    return GetSegmentCount() * mSegmentSize;
+  }
+
+  inline char* GetSegment(uint32_t aIndex)
+  {
+    NS_ASSERTION(aIndex < GetSegmentCount(), "index out of bounds");
+    int32_t i = ModSegArraySize(mFirstSegmentIndex + (int32_t)aIndex);
+    return mSegmentArray[i];
+  }
+
+protected:
+  inline int32_t ModSegArraySize(int32_t aIndex)
+  {
+    uint32_t result = aIndex & (mSegmentArrayCount - 1);
+    NS_ASSERTION(result == aIndex % mSegmentArrayCount,
+                 "non-power-of-2 mSegmentArrayCount");
+    return result;
+  }
+
+  inline bool IsFull()
+  {
+    return ModSegArraySize(mLastSegmentIndex + 1) == mFirstSegmentIndex;
+  }
+
+protected:
+  uint32_t            mSegmentSize;
+  uint32_t            mMaxSize;
+  char**              mSegmentArray;
+  uint32_t            mSegmentArrayCount;
+  int32_t             mFirstSegmentIndex;
+  int32_t             mLastSegmentIndex;
+};
+
+// NS_SEGMENTARRAY_INITIAL_SIZE: This number needs to start out as a
+// power of 2 given how it gets used. We double the segment array
+// when we overflow it, and use that fact that it's a power of 2
+// to compute a fast modulus operation in IsFull.
+//
+// 32 segment array entries can accommodate 128k of data if segments
+// are 4k in size. That seems like a reasonable amount that will avoid
+// needing to grow the segment array.
+#define NS_SEGMENTARRAY_INITIAL_COUNT 32
+
+#endif // nsSegmentedBuffer_h__
diff --git a/xpcom/io/nsStorageStream.cpp b/xpcom/io/nsStorageStream.cpp
new file mode 100644
index 000000000..3af7bb853
--- /dev/null
+++ b/xpcom/io/nsStorageStream.cpp
@@ -0,0 +1,648 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * The storage stream provides an internal buffer that can be filled by a
+ * client using a single output stream.  One or more independent input streams
+ * can be created to read the data out non-destructively.  The implementation
+ * uses a segmented buffer internally to avoid realloc'ing of large buffers,
+ * with the attendant performance loss and heap fragmentation.
+ */
+
+#include "nsAlgorithm.h"
+#include "nsStorageStream.h"
+#include "nsSegmentedBuffer.h"
+#include "nsStreamUtils.h"
+#include "nsCOMPtr.h"
+#include "nsICloneableInputStream.h"
+#include "nsIInputStream.h"
+#include "nsIIPCSerializableInputStream.h"
+#include "nsISeekableStream.h"
+#include "mozilla/Logging.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Likely.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/ipc/InputStreamUtils.h"
+
+using mozilla::ipc::InputStreamParams;
+using mozilla::ipc::StringInputStreamParams;
+using mozilla::Maybe;
+using mozilla::Some;
+
+//
+// Log module for StorageStream logging...
+//
+// To enable logging (see prlog.h for full details):
+//
+//    set MOZ_LOG=StorageStreamLog:5
+//    set MOZ_LOG_FILE=storage.log
+//
+// This enables LogLevel::Debug level information and places all output in
+// the file storage.log.
+//
+static LazyLogModule sStorageStreamLog("nsStorageStream");
+#ifdef LOG
+#undef LOG
+#endif
+#define LOG(args) MOZ_LOG(sStorageStreamLog, mozilla::LogLevel::Debug, args)
+
+nsStorageStream::nsStorageStream()
+  : mSegmentedBuffer(0), mSegmentSize(0), mWriteInProgress(false),
+    mLastSegmentNum(-1), mWriteCursor(0), mSegmentEnd(0), mLogicalLength(0)
+{
+  LOG(("Creating nsStorageStream [%p].\n", this));
+}
+
+nsStorageStream::~nsStorageStream()
+{
+  delete mSegmentedBuffer;
+}
+
+NS_IMPL_ISUPPORTS(nsStorageStream,
+                  nsIStorageStream,
+                  nsIOutputStream)
+
+NS_IMETHODIMP
+nsStorageStream::Init(uint32_t aSegmentSize, uint32_t aMaxSize)
+{
+  mSegmentedBuffer = new nsSegmentedBuffer();
+  mSegmentSize = aSegmentSize;
+  mSegmentSizeLog2 = mozilla::FloorLog2(aSegmentSize);
+
+  // Segment size must be a power of two
+  if (mSegmentSize != ((uint32_t)1 << mSegmentSizeLog2)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  return mSegmentedBuffer->Init(aSegmentSize, aMaxSize);
+}
+
+NS_IMETHODIMP
+nsStorageStream::GetOutputStream(int32_t aStartingOffset,
+                                 nsIOutputStream** aOutputStream)
+{
+  if (NS_WARN_IF(!aOutputStream)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  if (NS_WARN_IF(!mSegmentedBuffer)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  if (mWriteInProgress) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  nsresult rv = Seek(aStartingOffset);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // Enlarge the last segment in the buffer so that it is the same size as
+  // all the other segments in the buffer.  (It may have been realloc'ed
+  // smaller in the Close() method.)
+  if (mLastSegmentNum >= 0)
+    if (mSegmentedBuffer->ReallocLastSegment(mSegmentSize)) {
+      // Need to re-Seek, since realloc changed segment base pointer
+      rv = Seek(aStartingOffset);
+      if (NS_FAILED(rv)) {
+        return rv;
+      }
+    }
+
+  NS_ADDREF(this);
+  *aOutputStream = static_cast<nsIOutputStream*>(this);
+  mWriteInProgress = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageStream::Close()
+{
+  if (NS_WARN_IF(!mSegmentedBuffer)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  mWriteInProgress = false;
+
+  int32_t segmentOffset = SegOffset(mLogicalLength);
+
+  // Shrink the final segment in the segmented buffer to the minimum size
+  // needed to contain the data, so as to conserve memory.
+  if (segmentOffset) {
+    mSegmentedBuffer->ReallocLastSegment(segmentOffset);
+  }
+
+  mWriteCursor = 0;
+  mSegmentEnd = 0;
+
+  LOG(("nsStorageStream [%p] Close mWriteCursor=%x mSegmentEnd=%x\n",
+       this, mWriteCursor, mSegmentEnd));
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageStream::Flush()
+{
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageStream::Write(const char* aBuffer, uint32_t aCount,
+                       uint32_t* aNumWritten)
+{
+  if (NS_WARN_IF(!aNumWritten) || NS_WARN_IF(!aBuffer)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  if (NS_WARN_IF(!mSegmentedBuffer)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  const char* readCursor;
+  uint32_t count, availableInSegment, remaining;
+  nsresult rv = NS_OK;
+
+  LOG(("nsStorageStream [%p] Write mWriteCursor=%x mSegmentEnd=%x aCount=%d\n",
+       this, mWriteCursor, mSegmentEnd, aCount));
+
+  remaining = aCount;
+  readCursor = aBuffer;
+  // If no segments have been created yet, create one even if we don't have
+  // to write any data; this enables creating an input stream which reads from
+  // the very end of the data for any amount of data in the stream (i.e.
+  // this stream contains N bytes of data and newInputStream(N) is called),
+  // even for N=0 (with the caveat that we require .write("", 0) be called to
+  // initialize internal buffers).
+  bool firstTime = mSegmentedBuffer->GetSegmentCount() == 0;
+  while (remaining || MOZ_UNLIKELY(firstTime)) {
+    firstTime = false;
+    availableInSegment = mSegmentEnd - mWriteCursor;
+    if (!availableInSegment) {
+      mWriteCursor = mSegmentedBuffer->AppendNewSegment();
+      if (!mWriteCursor) {
+        mSegmentEnd = 0;
+        rv = NS_ERROR_OUT_OF_MEMORY;
+        goto out;
+      }
+      mLastSegmentNum++;
+      mSegmentEnd = mWriteCursor + mSegmentSize;
+      availableInSegment = mSegmentEnd - mWriteCursor;
+      LOG(("nsStorageStream [%p] Write (new seg) mWriteCursor=%x mSegmentEnd=%x\n",
+           this, mWriteCursor, mSegmentEnd));
+    }
+
+    count = XPCOM_MIN(availableInSegment, remaining);
+    memcpy(mWriteCursor, readCursor, count);
+    remaining -= count;
+    readCursor += count;
+    mWriteCursor += count;
+    LOG(("nsStorageStream [%p] Writing mWriteCursor=%x mSegmentEnd=%x count=%d\n",
+         this, mWriteCursor, mSegmentEnd, count));
+  }
+
+out:
+  *aNumWritten = aCount - remaining;
+  mLogicalLength += *aNumWritten;
+
+  LOG(("nsStorageStream [%p] Wrote mWriteCursor=%x mSegmentEnd=%x numWritten=%d\n",
+       this, mWriteCursor, mSegmentEnd, *aNumWritten));
+  return rv;
+}
+
+NS_IMETHODIMP
+nsStorageStream::WriteFrom(nsIInputStream* aInStr, uint32_t aCount,
+                           uint32_t* aResult)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsStorageStream::WriteSegments(nsReadSegmentFun aReader, void* aClosure,
+                               uint32_t aCount, uint32_t* aResult)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsStorageStream::IsNonBlocking(bool* aNonBlocking)
+{
+  *aNonBlocking = false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageStream::GetLength(uint32_t* aLength)
+{
+  *aLength = mLogicalLength;
+  return NS_OK;
+}
+
+// Truncate the buffer by deleting the end segments
+NS_IMETHODIMP
+nsStorageStream::SetLength(uint32_t aLength)
+{
+  if (NS_WARN_IF(!mSegmentedBuffer)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  if (mWriteInProgress) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  if (aLength > mLogicalLength) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  int32_t newLastSegmentNum = SegNum(aLength);
+  int32_t segmentOffset = SegOffset(aLength);
+  if (segmentOffset == 0) {
+    newLastSegmentNum--;
+  }
+
+  while (newLastSegmentNum < mLastSegmentNum) {
+    mSegmentedBuffer->DeleteLastSegment();
+    mLastSegmentNum--;
+  }
+
+  mLogicalLength = aLength;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageStream::GetWriteInProgress(bool* aWriteInProgress)
+{
+  *aWriteInProgress = mWriteInProgress;
+  return NS_OK;
+}
+
+nsresult
+nsStorageStream::Seek(int32_t aPosition)
+{
+  if (NS_WARN_IF(!mSegmentedBuffer)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  // An argument of -1 means "seek to end of stream"
+  if (aPosition == -1) {
+    aPosition = mLogicalLength;
+  }
+
+  // Seeking beyond the buffer end is illegal
+  if ((uint32_t)aPosition > mLogicalLength) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // Seeking backwards in the write stream results in truncation
+  SetLength(aPosition);
+
+  // Special handling for seek to start-of-buffer
+  if (aPosition == 0) {
+    mWriteCursor = 0;
+    mSegmentEnd = 0;
+    LOG(("nsStorageStream [%p] Seek mWriteCursor=%x mSegmentEnd=%x\n",
+         this, mWriteCursor, mSegmentEnd));
+    return NS_OK;
+  }
+
+  // Segment may have changed, so reset pointers
+  mWriteCursor = mSegmentedBuffer->GetSegment(mLastSegmentNum);
+  NS_ASSERTION(mWriteCursor, "null mWriteCursor");
+  mSegmentEnd = mWriteCursor + mSegmentSize;
+
+  // Adjust write cursor for current segment offset.  This test is necessary
+  // because SegNum may reference the next-to-be-allocated segment, in which
+  // case we need to be pointing at the end of the last segment.
+  int32_t segmentOffset = SegOffset(aPosition);
+  if (segmentOffset == 0 && (SegNum(aPosition) > (uint32_t) mLastSegmentNum)) {
+    mWriteCursor = mSegmentEnd;
+  } else {
+    mWriteCursor += segmentOffset;
+  }
+
+  LOG(("nsStorageStream [%p] Seek mWriteCursor=%x mSegmentEnd=%x\n",
+       this, mWriteCursor, mSegmentEnd));
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+// There can be many nsStorageInputStreams for a single nsStorageStream
+class nsStorageInputStream final
+  : public nsIInputStream
+  , public nsISeekableStream
+  , public nsIIPCSerializableInputStream
+  , public nsICloneableInputStream
+{
+public:
+  nsStorageInputStream(nsStorageStream* aStorageStream, uint32_t aSegmentSize)
+    : mStorageStream(aStorageStream), mReadCursor(0),
+      mSegmentEnd(0), mSegmentNum(0),
+      mSegmentSize(aSegmentSize), mLogicalCursor(0),
+      mStatus(NS_OK)
+  {
+  }
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIINPUTSTREAM
+  NS_DECL_NSISEEKABLESTREAM
+  NS_DECL_NSIIPCSERIALIZABLEINPUTSTREAM
+  NS_DECL_NSICLONEABLEINPUTSTREAM
+
+private:
+  ~nsStorageInputStream()
+  {
+  }
+
+protected:
+  nsresult Seek(uint32_t aPosition);
+
+  friend class nsStorageStream;
+
+private:
+  RefPtr<nsStorageStream> mStorageStream;
+  uint32_t         mReadCursor;    // Next memory location to read byte, or 0
+  uint32_t         mSegmentEnd;    // One byte past end of current buffer segment
+  uint32_t         mSegmentNum;    // Segment number containing read cursor
+  uint32_t         mSegmentSize;   // All segments, except the last, are of this size
+  uint32_t         mLogicalCursor; // Logical offset into stream
+  nsresult         mStatus;
+
+  uint32_t SegNum(uint32_t aPosition)
+  {
+    return aPosition >> mStorageStream->mSegmentSizeLog2;
+  }
+  uint32_t SegOffset(uint32_t aPosition)
+  {
+    return aPosition & (mSegmentSize - 1);
+  }
+};
+
+NS_IMPL_ISUPPORTS(nsStorageInputStream,
+                  nsIInputStream,
+                  nsISeekableStream,
+                  nsIIPCSerializableInputStream,
+                  nsICloneableInputStream)
+
+NS_IMETHODIMP
+nsStorageStream::NewInputStream(int32_t aStartingOffset,
+                                nsIInputStream** aInputStream)
+{
+  if (NS_WARN_IF(!mSegmentedBuffer)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  RefPtr<nsStorageInputStream> inputStream =
+    new nsStorageInputStream(this, mSegmentSize);
+
+  nsresult rv = inputStream->Seek(aStartingOffset);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  inputStream.forget(aInputStream);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::Close()
+{
+  mStatus = NS_BASE_STREAM_CLOSED;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::Available(uint64_t* aAvailable)
+{
+  if (NS_FAILED(mStatus)) {
+    return mStatus;
+  }
+
+  *aAvailable = mStorageStream->mLogicalLength - mLogicalCursor;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::Read(char* aBuffer, uint32_t aCount, uint32_t* aNumRead)
+{
+  return ReadSegments(NS_CopySegmentToBuffer, aBuffer, aCount, aNumRead);
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
+                                   uint32_t aCount, uint32_t* aNumRead)
+{
+  *aNumRead = 0;
+  if (mStatus == NS_BASE_STREAM_CLOSED) {
+    return NS_OK;
+  }
+  if (NS_FAILED(mStatus)) {
+    return mStatus;
+  }
+
+  uint32_t count, availableInSegment, remainingCapacity, bytesConsumed;
+  nsresult rv;
+
+  remainingCapacity = aCount;
+  while (remainingCapacity) {
+    availableInSegment = mSegmentEnd - mReadCursor;
+    if (!availableInSegment) {
+      uint32_t available = mStorageStream->mLogicalLength - mLogicalCursor;
+      if (!available) {
+        goto out;
+      }
+
+      // We have data in the stream, but if mSegmentEnd is zero, then we
+      // were likely constructed prior to any data being written into
+      // the stream.  Therefore, if mSegmentEnd is non-zero, we should
+      // move into the next segment; otherwise, we should stay in this
+      // segment so our input state can be updated and we can properly
+      // perform the initial read.
+      if (mSegmentEnd > 0) {
+        mSegmentNum++;
+      }
+      mReadCursor = 0;
+      mSegmentEnd = XPCOM_MIN(mSegmentSize, available);
+      availableInSegment = mSegmentEnd;
+    }
+    const char* cur = mStorageStream->mSegmentedBuffer->GetSegment(mSegmentNum);
+
+    count = XPCOM_MIN(availableInSegment, remainingCapacity);
+    rv = aWriter(this, aClosure, cur + mReadCursor, aCount - remainingCapacity,
+                 count, &bytesConsumed);
+    if (NS_FAILED(rv) || (bytesConsumed == 0)) {
+      break;
+    }
+    remainingCapacity -= bytesConsumed;
+    mReadCursor += bytesConsumed;
+    mLogicalCursor += bytesConsumed;
+  }
+
+out:
+  *aNumRead = aCount - remainingCapacity;
+
+  bool isWriteInProgress = false;
+  if (NS_FAILED(mStorageStream->GetWriteInProgress(&isWriteInProgress))) {
+    isWriteInProgress = false;
+  }
+
+  if (*aNumRead == 0 && isWriteInProgress) {
+    return NS_BASE_STREAM_WOULD_BLOCK;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::IsNonBlocking(bool* aNonBlocking)
+{
+  // TODO: This class should implement nsIAsyncInputStream so that callers
+  // have some way of dealing with NS_BASE_STREAM_WOULD_BLOCK errors.
+
+  *aNonBlocking = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::Seek(int32_t aWhence, int64_t aOffset)
+{
+  if (NS_FAILED(mStatus)) {
+    return mStatus;
+  }
+
+  int64_t pos = aOffset;
+
+  switch (aWhence) {
+    case NS_SEEK_SET:
+      break;
+    case NS_SEEK_CUR:
+      pos += mLogicalCursor;
+      break;
+    case NS_SEEK_END:
+      pos += mStorageStream->mLogicalLength;
+      break;
+    default:
+      NS_NOTREACHED("unexpected whence value");
+      return NS_ERROR_UNEXPECTED;
+  }
+  if (pos == int64_t(mLogicalCursor)) {
+    return NS_OK;
+  }
+
+  return Seek(pos);
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::Tell(int64_t* aResult)
+{
+  if (NS_FAILED(mStatus)) {
+    return mStatus;
+  }
+
+  *aResult = mLogicalCursor;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::SetEOF()
+{
+  NS_NOTREACHED("nsStorageInputStream::SetEOF");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+nsresult
+nsStorageInputStream::Seek(uint32_t aPosition)
+{
+  uint32_t length = mStorageStream->mLogicalLength;
+  if (aPosition > length) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  if (length == 0) {
+    return NS_OK;
+  }
+
+  mSegmentNum = SegNum(aPosition);
+  mReadCursor = SegOffset(aPosition);
+  uint32_t available = length - aPosition;
+  mSegmentEnd = mReadCursor + XPCOM_MIN(mSegmentSize - mReadCursor, available);
+  mLogicalCursor = aPosition;
+  return NS_OK;
+}
+
+void
+nsStorageInputStream::Serialize(InputStreamParams& aParams, FileDescriptorArray&)
+{
+  nsCString combined;
+  int64_t offset;
+  mozilla::DebugOnly<nsresult> rv = Tell(&offset);
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+
+  uint64_t remaining;
+  rv = Available(&remaining);
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+
+  combined.SetCapacity(remaining);
+  uint32_t numRead = 0;
+
+  rv = Read(combined.BeginWriting(), remaining, &numRead);
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+  MOZ_ASSERT(numRead == remaining);
+  combined.SetLength(numRead);
+
+  rv = Seek(NS_SEEK_SET, offset);
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+
+  StringInputStreamParams params;
+  params.data() = combined;
+  aParams = params;
+}
+
+Maybe<uint64_t>
+nsStorageInputStream::ExpectedSerializedLength()
+{
+  uint64_t remaining = 0;
+  DebugOnly<nsresult> rv = Available(&remaining);
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+  return Some(remaining);
+}
+
+bool
+nsStorageInputStream::Deserialize(const InputStreamParams& aParams,
+                                  const FileDescriptorArray&)
+{
+  NS_NOTREACHED("We should never attempt to deserialize a storage input stream.");
+  return false;
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::GetCloneable(bool* aCloneableOut)
+{
+  *aCloneableOut = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStorageInputStream::Clone(nsIInputStream** aCloneOut)
+{
+  return mStorageStream->NewInputStream(mLogicalCursor, aCloneOut);
+}
+
+nsresult
+NS_NewStorageStream(uint32_t aSegmentSize, uint32_t aMaxSize,
+                    nsIStorageStream** aResult)
+{
+  RefPtr<nsStorageStream> storageStream = new nsStorageStream();
+  nsresult rv = storageStream->Init(aSegmentSize, aMaxSize);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  storageStream.forget(aResult);
+  return NS_OK;
+}
+
+// Undefine LOG, so that other .cpp files (or their includes) won't complain
+// about it already being defined, when we build in unified mode.
+#undef LOG
diff --git a/xpcom/io/nsStorageStream.h b/xpcom/io/nsStorageStream.h
new file mode 100644
index 000000000..7fddd683e
--- /dev/null
+++ b/xpcom/io/nsStorageStream.h
@@ -0,0 +1,73 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * The storage stream provides an internal buffer that can be filled by a
+ * client using a single output stream.  One or more independent input streams
+ * can be created to read the data out non-destructively.  The implementation
+ * uses a segmented buffer internally to avoid realloc'ing of large buffers,
+ * with the attendant performance loss and heap fragmentation.
+ */
+
+#ifndef _nsStorageStream_h_
+#define _nsStorageStream_h_
+
+#include "nsIStorageStream.h"
+#include "nsIOutputStream.h"
+#include "nsMemory.h"
+#include "mozilla/Attributes.h"
+
+#define NS_STORAGESTREAM_CID                       \
+{ /* 669a9795-6ff7-4ed4-9150-c34ce2971b63 */       \
+  0x669a9795,                                      \
+  0x6ff7,                                          \
+  0x4ed4,                                          \
+  {0x91, 0x50, 0xc3, 0x4c, 0xe2, 0x97, 0x1b, 0x63} \
+}
+
+#define NS_STORAGESTREAM_CONTRACTID "@mozilla.org/storagestream;1"
+
+class nsSegmentedBuffer;
+
+class nsStorageStream final
+  : public nsIStorageStream
+  , public nsIOutputStream
+{
+public:
+  nsStorageStream();
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSISTORAGESTREAM
+  NS_DECL_NSIOUTPUTSTREAM
+
+  friend class nsStorageInputStream;
+
+private:
+  ~nsStorageStream();
+
+  nsSegmentedBuffer* mSegmentedBuffer;
+  uint32_t           mSegmentSize;       // All segments, except possibly the last, are of this size
+                                         //   Must be power-of-2
+  uint32_t           mSegmentSizeLog2;   // log2(mSegmentSize)
+  bool               mWriteInProgress;   // true, if an un-Close'ed output stream exists
+  int32_t            mLastSegmentNum;    // Last segment # in use, -1 initially
+  char*              mWriteCursor;       // Pointer to next byte to be written
+  char*              mSegmentEnd;        // Pointer to one byte after end of segment
+                                         //   containing the write cursor
+  uint32_t           mLogicalLength;     // Number of bytes written to stream
+
+  nsresult Seek(int32_t aPosition);
+  uint32_t SegNum(uint32_t aPosition)
+  {
+    return aPosition >> mSegmentSizeLog2;
+  }
+  uint32_t SegOffset(uint32_t aPosition)
+  {
+    return aPosition & (mSegmentSize - 1);
+  }
+};
+
+#endif //  _nsStorageStream_h_
diff --git a/xpcom/io/nsStreamUtils.cpp b/xpcom/io/nsStreamUtils.cpp
new file mode 100644
index 000000000..891dad59f
--- /dev/null
+++ b/xpcom/io/nsStreamUtils.cpp
@@ -0,0 +1,957 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Mutex.h"
+#include "mozilla/Attributes.h"
+#include "nsStreamUtils.h"
+#include "nsAutoPtr.h"
+#include "nsCOMPtr.h"
+#include "nsIPipe.h"
+#include "nsICloneableInputStream.h"
+#include "nsIEventTarget.h"
+#include "nsICancelableRunnable.h"
+#include "nsISafeOutputStream.h"
+#include "nsString.h"
+#include "nsIAsyncInputStream.h"
+#include "nsIAsyncOutputStream.h"
+#include "nsIBufferedStreams.h"
+#include "nsNetCID.h"
+#include "nsServiceManagerUtils.h"
+#include "nsThreadUtils.h"
+
+using namespace mozilla;
+
+//-----------------------------------------------------------------------------
+
+// This is a nsICancelableRunnable because we can dispatch it to Workers and
+// those can be shut down at any time, and in these cases, Cancel() is called
+// instead of Run().
+class nsInputStreamReadyEvent final
+  : public CancelableRunnable
+  , public nsIInputStreamCallback
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+
+  nsInputStreamReadyEvent(nsIInputStreamCallback* aCallback,
+                          nsIEventTarget* aTarget)
+    : mCallback(aCallback)
+    , mTarget(aTarget)
+  {
+  }
+
+private:
+  ~nsInputStreamReadyEvent()
+  {
+    if (!mCallback) {
+      return;
+    }
+    //
+    // whoa!!  looks like we never posted this event.  take care to
+    // release mCallback on the correct thread.  if mTarget lives on the
+    // calling thread, then we are ok.  otherwise, we have to try to
+    // proxy the Release over the right thread.  if that thread is dead,
+    // then there's nothing we can do... better to leak than crash.
+    //
+    bool val;
+    nsresult rv = mTarget->IsOnCurrentThread(&val);
+    if (NS_FAILED(rv) || !val) {
+      nsCOMPtr<nsIInputStreamCallback> event =
+        NS_NewInputStreamReadyEvent(mCallback, mTarget);
+      mCallback = nullptr;
+      if (event) {
+        rv = event->OnInputStreamReady(nullptr);
+        if (NS_FAILED(rv)) {
+          NS_NOTREACHED("leaking stream event");
+          nsISupports* sup = event;
+          NS_ADDREF(sup);
+        }
+      }
+    }
+  }
+
+public:
+  NS_IMETHOD OnInputStreamReady(nsIAsyncInputStream* aStream) override
+  {
+    mStream = aStream;
+
+    nsresult rv =
+      mTarget->Dispatch(this, NS_DISPATCH_NORMAL);
+    if (NS_FAILED(rv)) {
+      NS_WARNING("Dispatch failed");
+      return NS_ERROR_FAILURE;
+    }
+
+    return NS_OK;
+  }
+
+  NS_IMETHOD Run() override
+  {
+    if (mCallback) {
+      if (mStream) {
+        mCallback->OnInputStreamReady(mStream);
+      }
+      mCallback = nullptr;
+    }
+    return NS_OK;
+  }
+
+  nsresult Cancel() override
+  {
+    mCallback = nullptr;
+    return NS_OK;
+  }
+
+private:
+  nsCOMPtr<nsIAsyncInputStream>    mStream;
+  nsCOMPtr<nsIInputStreamCallback> mCallback;
+  nsCOMPtr<nsIEventTarget>         mTarget;
+};
+
+NS_IMPL_ISUPPORTS_INHERITED(nsInputStreamReadyEvent, CancelableRunnable,
+                            nsIInputStreamCallback)
+
+//-----------------------------------------------------------------------------
+
+// This is a nsICancelableRunnable because we can dispatch it to Workers and
+// those can be shut down at any time, and in these cases, Cancel() is called
+// instead of Run().
+class nsOutputStreamReadyEvent final
+  : public CancelableRunnable
+  , public nsIOutputStreamCallback
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+
+  nsOutputStreamReadyEvent(nsIOutputStreamCallback* aCallback,
+                           nsIEventTarget* aTarget)
+    : mCallback(aCallback)
+    , mTarget(aTarget)
+  {
+  }
+
+private:
+  ~nsOutputStreamReadyEvent()
+  {
+    if (!mCallback) {
+      return;
+    }
+    //
+    // whoa!!  looks like we never posted this event.  take care to
+    // release mCallback on the correct thread.  if mTarget lives on the
+    // calling thread, then we are ok.  otherwise, we have to try to
+    // proxy the Release over the right thread.  if that thread is dead,
+    // then there's nothing we can do... better to leak than crash.
+    //
+    bool val;
+    nsresult rv = mTarget->IsOnCurrentThread(&val);
+    if (NS_FAILED(rv) || !val) {
+      nsCOMPtr<nsIOutputStreamCallback> event =
+        NS_NewOutputStreamReadyEvent(mCallback, mTarget);
+      mCallback = nullptr;
+      if (event) {
+        rv = event->OnOutputStreamReady(nullptr);
+        if (NS_FAILED(rv)) {
+          NS_NOTREACHED("leaking stream event");
+          nsISupports* sup = event;
+          NS_ADDREF(sup);
+        }
+      }
+    }
+  }
+
+public:
+  NS_IMETHOD OnOutputStreamReady(nsIAsyncOutputStream* aStream) override
+  {
+    mStream = aStream;
+
+    nsresult rv =
+      mTarget->Dispatch(this, NS_DISPATCH_NORMAL);
+    if (NS_FAILED(rv)) {
+      NS_WARNING("PostEvent failed");
+      return NS_ERROR_FAILURE;
+    }
+
+    return NS_OK;
+  }
+
+  NS_IMETHOD Run() override
+  {
+    if (mCallback) {
+      if (mStream) {
+        mCallback->OnOutputStreamReady(mStream);
+      }
+      mCallback = nullptr;
+    }
+    return NS_OK;
+  }
+
+  nsresult Cancel() override
+  {
+    mCallback = nullptr;
+    return NS_OK;
+  }
+
+private:
+  nsCOMPtr<nsIAsyncOutputStream>    mStream;
+  nsCOMPtr<nsIOutputStreamCallback> mCallback;
+  nsCOMPtr<nsIEventTarget>          mTarget;
+};
+
+NS_IMPL_ISUPPORTS_INHERITED(nsOutputStreamReadyEvent, CancelableRunnable,
+                            nsIOutputStreamCallback)
+
+//-----------------------------------------------------------------------------
+
+already_AddRefed<nsIInputStreamCallback>
+NS_NewInputStreamReadyEvent(nsIInputStreamCallback* aCallback,
+                            nsIEventTarget* aTarget)
+{
+  NS_ASSERTION(aCallback, "null callback");
+  NS_ASSERTION(aTarget, "null target");
+  RefPtr<nsInputStreamReadyEvent> ev =
+    new nsInputStreamReadyEvent(aCallback, aTarget);
+  return ev.forget();
+}
+
+already_AddRefed<nsIOutputStreamCallback>
+NS_NewOutputStreamReadyEvent(nsIOutputStreamCallback* aCallback,
+                             nsIEventTarget* aTarget)
+{
+  NS_ASSERTION(aCallback, "null callback");
+  NS_ASSERTION(aTarget, "null target");
+  RefPtr<nsOutputStreamReadyEvent> ev =
+    new nsOutputStreamReadyEvent(aCallback, aTarget);
+  return ev.forget();
+}
+
+//-----------------------------------------------------------------------------
+// NS_AsyncCopy implementation
+
+// abstract stream copier...
+class nsAStreamCopier
+  : public nsIInputStreamCallback
+  , public nsIOutputStreamCallback
+  , public CancelableRunnable
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+
+  nsAStreamCopier()
+    : mLock("nsAStreamCopier.mLock")
+    , mCallback(nullptr)
+    , mProgressCallback(nullptr)
+    , mClosure(nullptr)
+    , mChunkSize(0)
+    , mEventInProcess(false)
+    , mEventIsPending(false)
+    , mCloseSource(true)
+    , mCloseSink(true)
+    , mCanceled(false)
+    , mCancelStatus(NS_OK)
+  {
+  }
+
+  // kick off the async copy...
+  nsresult Start(nsIInputStream* aSource,
+                 nsIOutputStream* aSink,
+                 nsIEventTarget* aTarget,
+                 nsAsyncCopyCallbackFun aCallback,
+                 void* aClosure,
+                 uint32_t aChunksize,
+                 bool aCloseSource,
+                 bool aCloseSink,
+                 nsAsyncCopyProgressFun aProgressCallback)
+  {
+    mSource = aSource;
+    mSink = aSink;
+    mTarget = aTarget;
+    mCallback = aCallback;
+    mClosure = aClosure;
+    mChunkSize = aChunksize;
+    mCloseSource = aCloseSource;
+    mCloseSink = aCloseSink;
+    mProgressCallback = aProgressCallback;
+
+    mAsyncSource = do_QueryInterface(mSource);
+    mAsyncSink = do_QueryInterface(mSink);
+
+    return PostContinuationEvent();
+  }
+
+  // implemented by subclasses, returns number of bytes copied and
+  // sets source and sink condition before returning.
+  virtual uint32_t DoCopy(nsresult* aSourceCondition,
+                          nsresult* aSinkCondition) = 0;
+
+  void Process()
+  {
+    if (!mSource || !mSink) {
+      return;
+    }
+
+    nsresult cancelStatus;
+    bool canceled;
+    {
+      MutexAutoLock lock(mLock);
+      canceled = mCanceled;
+      cancelStatus = mCancelStatus;
+    }
+
+    // If the copy was canceled before Process() was even called, then
+    // sourceCondition and sinkCondition should be set to error results to
+    // ensure we don't call Finish() on a canceled nsISafeOutputStream.
+    MOZ_ASSERT(NS_FAILED(cancelStatus) == canceled, "cancel needs an error");
+    nsresult sourceCondition = cancelStatus;
+    nsresult sinkCondition = cancelStatus;
+
+    // Copy data from the source to the sink until we hit failure or have
+    // copied all the data.
+    for (;;) {
+      // Note: copyFailed will be true if the source or the sink have
+      //       reported an error, or if we failed to write any bytes
+      //       because we have consumed all of our data.
+      bool copyFailed = false;
+      if (!canceled) {
+        uint32_t n = DoCopy(&sourceCondition, &sinkCondition);
+        if (n > 0 && mProgressCallback) {
+          mProgressCallback(mClosure, n);
+        }
+        copyFailed = NS_FAILED(sourceCondition) ||
+                     NS_FAILED(sinkCondition) || n == 0;
+
+        MutexAutoLock lock(mLock);
+        canceled = mCanceled;
+        cancelStatus = mCancelStatus;
+      }
+      if (copyFailed && !canceled) {
+        if (sourceCondition == NS_BASE_STREAM_WOULD_BLOCK && mAsyncSource) {
+          // need to wait for more data from source.  while waiting for
+          // more source data, be sure to observe failures on output end.
+          mAsyncSource->AsyncWait(this, 0, 0, nullptr);
+
+          if (mAsyncSink)
+            mAsyncSink->AsyncWait(this,
+                                  nsIAsyncOutputStream::WAIT_CLOSURE_ONLY,
+                                  0, nullptr);
+          break;
+        } else if (sinkCondition == NS_BASE_STREAM_WOULD_BLOCK && mAsyncSink) {
+          // need to wait for more room in the sink.  while waiting for
+          // more room in the sink, be sure to observer failures on the
+          // input end.
+          mAsyncSink->AsyncWait(this, 0, 0, nullptr);
+
+          if (mAsyncSource)
+            mAsyncSource->AsyncWait(this,
+                                    nsIAsyncInputStream::WAIT_CLOSURE_ONLY,
+                                    0, nullptr);
+          break;
+        }
+      }
+      if (copyFailed || canceled) {
+        if (mCloseSource) {
+          // close source
+          if (mAsyncSource)
+            mAsyncSource->CloseWithStatus(
+              canceled ? cancelStatus : sinkCondition);
+          else {
+            mSource->Close();
+          }
+        }
+        mAsyncSource = nullptr;
+        mSource = nullptr;
+
+        if (mCloseSink) {
+          // close sink
+          if (mAsyncSink)
+            mAsyncSink->CloseWithStatus(
+              canceled ? cancelStatus : sourceCondition);
+          else {
+            // If we have an nsISafeOutputStream, and our
+            // sourceCondition and sinkCondition are not set to a
+            // failure state, finish writing.
+            nsCOMPtr<nsISafeOutputStream> sostream =
+              do_QueryInterface(mSink);
+            if (sostream && NS_SUCCEEDED(sourceCondition) &&
+                NS_SUCCEEDED(sinkCondition)) {
+              sostream->Finish();
+            } else {
+              mSink->Close();
+            }
+          }
+        }
+        mAsyncSink = nullptr;
+        mSink = nullptr;
+
+        // notify state complete...
+        if (mCallback) {
+          nsresult status;
+          if (!canceled) {
+            status = sourceCondition;
+            if (NS_SUCCEEDED(status)) {
+              status = sinkCondition;
+            }
+            if (status == NS_BASE_STREAM_CLOSED) {
+              status = NS_OK;
+            }
+          } else {
+            status = cancelStatus;
+          }
+          mCallback(mClosure, status);
+        }
+        break;
+      }
+    }
+  }
+
+  nsresult Cancel(nsresult aReason)
+  {
+    MutexAutoLock lock(mLock);
+    if (mCanceled) {
+      return NS_ERROR_FAILURE;
+    }
+
+    if (NS_SUCCEEDED(aReason)) {
+      NS_WARNING("cancel with non-failure status code");
+      aReason = NS_BASE_STREAM_CLOSED;
+    }
+
+    mCanceled = true;
+    mCancelStatus = aReason;
+    return NS_OK;
+  }
+
+  NS_IMETHOD OnInputStreamReady(nsIAsyncInputStream* aSource) override
+  {
+    PostContinuationEvent();
+    return NS_OK;
+  }
+
+  NS_IMETHOD OnOutputStreamReady(nsIAsyncOutputStream* aSink) override
+  {
+    PostContinuationEvent();
+    return NS_OK;
+  }
+
+  // continuation event handler
+  NS_IMETHOD Run() override
+  {
+    Process();
+
+    // clear "in process" flag and post any pending continuation event
+    MutexAutoLock lock(mLock);
+    mEventInProcess = false;
+    if (mEventIsPending) {
+      mEventIsPending = false;
+      PostContinuationEvent_Locked();
+    }
+
+    return NS_OK;
+  }
+
+  nsresult Cancel() MOZ_MUST_OVERRIDE override = 0;
+
+  nsresult PostContinuationEvent()
+  {
+    // we cannot post a continuation event if there is currently
+    // an event in process.  doing so could result in Process being
+    // run simultaneously on multiple threads, so we mark the event
+    // as pending, and if an event is already in process then we
+    // just let that existing event take care of posting the real
+    // continuation event.
+
+    MutexAutoLock lock(mLock);
+    return PostContinuationEvent_Locked();
+  }
+
+  nsresult PostContinuationEvent_Locked()
+  {
+    nsresult rv = NS_OK;
+    if (mEventInProcess) {
+      mEventIsPending = true;
+    } else {
+      rv = mTarget->Dispatch(this, NS_DISPATCH_NORMAL);
+      if (NS_SUCCEEDED(rv)) {
+        mEventInProcess = true;
+      } else {
+        NS_WARNING("unable to post continuation event");
+      }
+    }
+    return rv;
+  }
+
+protected:
+  nsCOMPtr<nsIInputStream>       mSource;
+  nsCOMPtr<nsIOutputStream>      mSink;
+  nsCOMPtr<nsIAsyncInputStream>  mAsyncSource;
+  nsCOMPtr<nsIAsyncOutputStream> mAsyncSink;
+  nsCOMPtr<nsIEventTarget>       mTarget;
+  Mutex                          mLock;
+  nsAsyncCopyCallbackFun         mCallback;
+  nsAsyncCopyProgressFun         mProgressCallback;
+  void*                          mClosure;
+  uint32_t                       mChunkSize;
+  bool                           mEventInProcess;
+  bool                           mEventIsPending;
+  bool                           mCloseSource;
+  bool                           mCloseSink;
+  bool                           mCanceled;
+  nsresult                       mCancelStatus;
+
+  // virtual since subclasses call superclass Release()
+  virtual ~nsAStreamCopier()
+  {
+  }
+};
+
+NS_IMPL_ISUPPORTS_INHERITED(nsAStreamCopier,
+                            CancelableRunnable,
+                            nsIInputStreamCallback,
+                            nsIOutputStreamCallback)
+
+class nsStreamCopierIB final : public nsAStreamCopier
+{
+public:
+  nsStreamCopierIB() : nsAStreamCopier()
+  {
+  }
+  virtual ~nsStreamCopierIB()
+  {
+  }
+
+  struct MOZ_STACK_CLASS ReadSegmentsState
+  {
+    // the nsIOutputStream will outlive the ReadSegmentsState on the stack
+    nsIOutputStream* MOZ_NON_OWNING_REF mSink;
+    nsresult         mSinkCondition;
+  };
+
+  static nsresult ConsumeInputBuffer(nsIInputStream* aInStr,
+                                     void* aClosure,
+                                     const char* aBuffer,
+                                     uint32_t aOffset,
+                                     uint32_t aCount,
+                                     uint32_t* aCountWritten)
+  {
+    ReadSegmentsState* state = (ReadSegmentsState*)aClosure;
+
+    nsresult rv = state->mSink->Write(aBuffer, aCount, aCountWritten);
+    if (NS_FAILED(rv)) {
+      state->mSinkCondition = rv;
+    } else if (*aCountWritten == 0) {
+      state->mSinkCondition = NS_BASE_STREAM_CLOSED;
+    }
+
+    return state->mSinkCondition;
+  }
+
+  uint32_t DoCopy(nsresult* aSourceCondition,
+                  nsresult* aSinkCondition) override
+  {
+    ReadSegmentsState state;
+    state.mSink = mSink;
+    state.mSinkCondition = NS_OK;
+
+    uint32_t n;
+    *aSourceCondition =
+      mSource->ReadSegments(ConsumeInputBuffer, &state, mChunkSize, &n);
+    *aSinkCondition = state.mSinkCondition;
+    return n;
+  }
+
+  nsresult Cancel() override
+  {
+    return NS_OK;
+  }
+};
+
+class nsStreamCopierOB final : public nsAStreamCopier
+{
+public:
+  nsStreamCopierOB() : nsAStreamCopier()
+  {
+  }
+  virtual ~nsStreamCopierOB()
+  {
+  }
+
+  struct MOZ_STACK_CLASS WriteSegmentsState
+  {
+    // the nsIInputStream will outlive the WriteSegmentsState on the stack
+    nsIInputStream* MOZ_NON_OWNING_REF mSource;
+    nsresult        mSourceCondition;
+  };
+
+  static nsresult FillOutputBuffer(nsIOutputStream* aOutStr,
+                                   void* aClosure,
+                                   char* aBuffer,
+                                   uint32_t aOffset,
+                                   uint32_t aCount,
+                                   uint32_t* aCountRead)
+  {
+    WriteSegmentsState* state = (WriteSegmentsState*)aClosure;
+
+    nsresult rv = state->mSource->Read(aBuffer, aCount, aCountRead);
+    if (NS_FAILED(rv)) {
+      state->mSourceCondition = rv;
+    } else if (*aCountRead == 0) {
+      state->mSourceCondition = NS_BASE_STREAM_CLOSED;
+    }
+
+    return state->mSourceCondition;
+  }
+
+  uint32_t DoCopy(nsresult* aSourceCondition,
+                  nsresult* aSinkCondition) override
+  {
+    WriteSegmentsState state;
+    state.mSource = mSource;
+    state.mSourceCondition = NS_OK;
+
+    uint32_t n;
+    *aSinkCondition =
+      mSink->WriteSegments(FillOutputBuffer, &state, mChunkSize, &n);
+    *aSourceCondition = state.mSourceCondition;
+    return n;
+  }
+
+  nsresult Cancel() override
+  {
+    return NS_OK;
+  }
+};
+
+//-----------------------------------------------------------------------------
+
+nsresult
+NS_AsyncCopy(nsIInputStream*         aSource,
+             nsIOutputStream*        aSink,
+             nsIEventTarget*         aTarget,
+             nsAsyncCopyMode         aMode,
+             uint32_t                aChunkSize,
+             nsAsyncCopyCallbackFun  aCallback,
+             void*                   aClosure,
+             bool                    aCloseSource,
+             bool                    aCloseSink,
+             nsISupports**           aCopierCtx,
+             nsAsyncCopyProgressFun  aProgressCallback)
+{
+  NS_ASSERTION(aTarget, "non-null target required");
+
+  nsresult rv;
+  nsAStreamCopier* copier;
+
+  if (aMode == NS_ASYNCCOPY_VIA_READSEGMENTS) {
+    copier = new nsStreamCopierIB();
+  } else {
+    copier = new nsStreamCopierOB();
+  }
+
+  // Start() takes an owning ref to the copier...
+  NS_ADDREF(copier);
+  rv = copier->Start(aSource, aSink, aTarget, aCallback, aClosure, aChunkSize,
+                     aCloseSource, aCloseSink, aProgressCallback);
+
+  if (aCopierCtx) {
+    *aCopierCtx = static_cast<nsISupports*>(static_cast<nsIRunnable*>(copier));
+    NS_ADDREF(*aCopierCtx);
+  }
+  NS_RELEASE(copier);
+
+  return rv;
+}
+
+//-----------------------------------------------------------------------------
+
+nsresult
+NS_CancelAsyncCopy(nsISupports* aCopierCtx, nsresult aReason)
+{
+  nsAStreamCopier* copier =
+    static_cast<nsAStreamCopier*>(static_cast<nsIRunnable *>(aCopierCtx));
+  return copier->Cancel(aReason);
+}
+
+//-----------------------------------------------------------------------------
+
+nsresult
+NS_ConsumeStream(nsIInputStream* aStream, uint32_t aMaxCount,
+                 nsACString& aResult)
+{
+  nsresult rv = NS_OK;
+  aResult.Truncate();
+
+  while (aMaxCount) {
+    uint64_t avail64;
+    rv = aStream->Available(&avail64);
+    if (NS_FAILED(rv)) {
+      if (rv == NS_BASE_STREAM_CLOSED) {
+        rv = NS_OK;
+      }
+      break;
+    }
+    if (avail64 == 0) {
+      break;
+    }
+
+    uint32_t avail = (uint32_t)XPCOM_MIN<uint64_t>(avail64, aMaxCount);
+
+    // resize aResult buffer
+    uint32_t length = aResult.Length();
+    if (avail > UINT32_MAX - length) {
+      return NS_ERROR_FILE_TOO_BIG;
+    }
+
+    aResult.SetLength(length + avail);
+    if (aResult.Length() != (length + avail)) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    char* buf = aResult.BeginWriting() + length;
+
+    uint32_t n;
+    rv = aStream->Read(buf, avail, &n);
+    if (NS_FAILED(rv)) {
+      break;
+    }
+    if (n != avail) {
+      aResult.SetLength(length + n);
+    }
+    if (n == 0) {
+      break;
+    }
+    aMaxCount -= n;
+  }
+
+  return rv;
+}
+
+//-----------------------------------------------------------------------------
+
+static nsresult
+TestInputStream(nsIInputStream* aInStr,
+                void* aClosure,
+                const char* aBuffer,
+                uint32_t aOffset,
+                uint32_t aCount,
+                uint32_t* aCountWritten)
+{
+  bool* result = static_cast<bool*>(aClosure);
+  *result = true;
+  return NS_ERROR_ABORT;  // don't call me anymore
+}
+
+bool
+NS_InputStreamIsBuffered(nsIInputStream* aStream)
+{
+  nsCOMPtr<nsIBufferedInputStream> bufferedIn = do_QueryInterface(aStream);
+  if (bufferedIn) {
+    return true;
+  }
+
+  bool result = false;
+  uint32_t n;
+  nsresult rv = aStream->ReadSegments(TestInputStream, &result, 1, &n);
+  return result || NS_SUCCEEDED(rv);
+}
+
+static nsresult
+TestOutputStream(nsIOutputStream* aOutStr,
+                 void* aClosure,
+                 char* aBuffer,
+                 uint32_t aOffset,
+                 uint32_t aCount,
+                 uint32_t* aCountRead)
+{
+  bool* result = static_cast<bool*>(aClosure);
+  *result = true;
+  return NS_ERROR_ABORT;  // don't call me anymore
+}
+
+bool
+NS_OutputStreamIsBuffered(nsIOutputStream* aStream)
+{
+  nsCOMPtr<nsIBufferedOutputStream> bufferedOut = do_QueryInterface(aStream);
+  if (bufferedOut) {
+    return true;
+  }
+
+  bool result = false;
+  uint32_t n;
+  aStream->WriteSegments(TestOutputStream, &result, 1, &n);
+  return result;
+}
+
+//-----------------------------------------------------------------------------
+
+nsresult
+NS_CopySegmentToStream(nsIInputStream* aInStr,
+                       void* aClosure,
+                       const char* aBuffer,
+                       uint32_t aOffset,
+                       uint32_t aCount,
+                       uint32_t* aCountWritten)
+{
+  nsIOutputStream* outStr = static_cast<nsIOutputStream*>(aClosure);
+  *aCountWritten = 0;
+  while (aCount) {
+    uint32_t n;
+    nsresult rv = outStr->Write(aBuffer, aCount, &n);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+    aBuffer += n;
+    aCount -= n;
+    *aCountWritten += n;
+  }
+  return NS_OK;
+}
+
+nsresult
+NS_CopySegmentToBuffer(nsIInputStream* aInStr,
+                       void* aClosure,
+                       const char* aBuffer,
+                       uint32_t aOffset,
+                       uint32_t aCount,
+                       uint32_t* aCountWritten)
+{
+  char* toBuf = static_cast<char*>(aClosure);
+  memcpy(&toBuf[aOffset], aBuffer, aCount);
+  *aCountWritten = aCount;
+  return NS_OK;
+}
+
+nsresult
+NS_CopySegmentToBuffer(nsIOutputStream* aOutStr,
+                       void* aClosure,
+                       char* aBuffer,
+                       uint32_t aOffset,
+                       uint32_t aCount,
+                       uint32_t* aCountRead)
+{
+  const char* fromBuf = static_cast<const char*>(aClosure);
+  memcpy(aBuffer, &fromBuf[aOffset], aCount);
+  *aCountRead = aCount;
+  return NS_OK;
+}
+
+nsresult
+NS_DiscardSegment(nsIInputStream* aInStr,
+                  void* aClosure,
+                  const char* aBuffer,
+                  uint32_t aOffset,
+                  uint32_t aCount,
+                  uint32_t* aCountWritten)
+{
+  *aCountWritten = aCount;
+  return NS_OK;
+}
+
+//-----------------------------------------------------------------------------
+
+nsresult
+NS_WriteSegmentThunk(nsIInputStream* aInStr,
+                     void* aClosure,
+                     const char* aBuffer,
+                     uint32_t aOffset,
+                     uint32_t aCount,
+                     uint32_t* aCountWritten)
+{
+  nsWriteSegmentThunk* thunk = static_cast<nsWriteSegmentThunk*>(aClosure);
+  return thunk->mFun(thunk->mStream, thunk->mClosure, aBuffer, aOffset, aCount,
+                     aCountWritten);
+}
+
+nsresult
+NS_FillArray(FallibleTArray<char>& aDest, nsIInputStream* aInput,
+             uint32_t aKeep, uint32_t* aNewBytes)
+{
+  MOZ_ASSERT(aInput, "null stream");
+  MOZ_ASSERT(aKeep <= aDest.Length(), "illegal keep count");
+
+  char* aBuffer = aDest.Elements();
+  int64_t keepOffset = int64_t(aDest.Length()) - aKeep;
+  if (aKeep != 0 && keepOffset > 0) {
+    memmove(aBuffer, aBuffer + keepOffset, aKeep);
+  }
+
+  nsresult rv =
+    aInput->Read(aBuffer + aKeep, aDest.Capacity() - aKeep, aNewBytes);
+  if (NS_FAILED(rv)) {
+    *aNewBytes = 0;
+  }
+  // NOTE: we rely on the fact that the new slots are NOT initialized by
+  // SetLengthAndRetainStorage here, see nsTArrayElementTraits::Construct()
+  // in nsTArray.h:
+  aDest.SetLengthAndRetainStorage(aKeep + *aNewBytes);
+
+  MOZ_ASSERT(aDest.Length() <= aDest.Capacity(), "buffer overflow");
+  return rv;
+}
+
+bool
+NS_InputStreamIsCloneable(nsIInputStream* aSource)
+{
+  if (!aSource) {
+    return false;
+  }
+
+  nsCOMPtr<nsICloneableInputStream> cloneable = do_QueryInterface(aSource);
+  return cloneable && cloneable->GetCloneable();
+}
+
+nsresult
+NS_CloneInputStream(nsIInputStream* aSource, nsIInputStream** aCloneOut,
+                    nsIInputStream** aReplacementOut)
+{
+  if (NS_WARN_IF(!aSource)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Attempt to perform the clone directly on the source stream
+  nsCOMPtr<nsICloneableInputStream> cloneable = do_QueryInterface(aSource);
+  if (cloneable && cloneable->GetCloneable()) {
+    if (aReplacementOut) {
+      *aReplacementOut = nullptr;
+    }
+    return cloneable->Clone(aCloneOut);
+  }
+
+  // If we failed the clone and the caller does not want to replace their
+  // original stream, then we are done.  Return error.
+  if (!aReplacementOut) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // The caller has opted-in to the fallback clone support that replaces
+  // the original stream.  Copy the data to a pipe and return two cloned
+  // input streams.
+
+  nsCOMPtr<nsIInputStream> reader;
+  nsCOMPtr<nsIInputStream> readerClone;
+  nsCOMPtr<nsIOutputStream> writer;
+
+  nsresult rv = NS_NewPipe(getter_AddRefs(reader), getter_AddRefs(writer),
+                           0, 0,        // default segment size and max size
+                           true, true); // non-blocking
+  if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+
+  cloneable = do_QueryInterface(reader);
+  MOZ_ASSERT(cloneable && cloneable->GetCloneable());
+
+  rv = cloneable->Clone(getter_AddRefs(readerClone));
+  if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+
+  nsCOMPtr<nsIEventTarget> target =
+    do_GetService(NS_STREAMTRANSPORTSERVICE_CONTRACTID, &rv);
+  if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+
+  rv = NS_AsyncCopy(aSource, writer, target, NS_ASYNCCOPY_VIA_WRITESEGMENTS);
+  if (NS_WARN_IF(NS_FAILED(rv))) { return rv; }
+
+  readerClone.forget(aCloneOut);
+  reader.forget(aReplacementOut);
+
+  return NS_OK;
+}
diff --git a/xpcom/io/nsStreamUtils.h b/xpcom/io/nsStreamUtils.h
new file mode 100644
index 000000000..957eb2713
--- /dev/null
+++ b/xpcom/io/nsStreamUtils.h
@@ -0,0 +1,295 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsStreamUtils_h__
+#define nsStreamUtils_h__
+
+#include "nsCOMPtr.h"
+#include "nsStringFwd.h"
+#include "nsIInputStream.h"
+#include "nsTArray.h"
+
+class nsIOutputStream;
+class nsIInputStreamCallback;
+class nsIOutputStreamCallback;
+class nsIEventTarget;
+
+/**
+ * A "one-shot" proxy of the OnInputStreamReady callback.  The resulting
+ * proxy object's OnInputStreamReady function may only be called once!  The
+ * proxy object ensures that the real notify object will be free'd on the
+ * thread corresponding to the given event target regardless of what thread
+ * the proxy object is destroyed on.
+ *
+ * This function is designed to be used to implement AsyncWait when the
+ * aTarget parameter is non-null.
+ */
+extern already_AddRefed<nsIInputStreamCallback>
+NS_NewInputStreamReadyEvent(nsIInputStreamCallback* aNotify,
+                            nsIEventTarget* aTarget);
+
+/**
+ * A "one-shot" proxy of the OnOutputStreamReady callback.  The resulting
+ * proxy object's OnOutputStreamReady function may only be called once!  The
+ * proxy object ensures that the real notify object will be free'd on the
+ * thread corresponding to the given event target regardless of what thread
+ * the proxy object is destroyed on.
+ *
+ * This function is designed to be used to implement AsyncWait when the
+ * aTarget parameter is non-null.
+ */
+extern already_AddRefed<nsIOutputStreamCallback>
+NS_NewOutputStreamReadyEvent(nsIOutputStreamCallback* aNotify,
+                             nsIEventTarget* aTarget);
+
+/* ------------------------------------------------------------------------- */
+
+enum nsAsyncCopyMode {
+  NS_ASYNCCOPY_VIA_READSEGMENTS,
+  NS_ASYNCCOPY_VIA_WRITESEGMENTS
+};
+
+/**
+ * This function is called when a new chunk of data has been copied.  The
+ * reported count is the size of the current chunk.
+ */
+typedef void (* nsAsyncCopyProgressFun)(void* closure, uint32_t count);
+
+/**
+ * This function is called when the async copy process completes.  The reported
+ * status is NS_OK on success and some error code on failure.
+ */
+typedef void (* nsAsyncCopyCallbackFun)(void* closure, nsresult status);
+
+/**
+ * This function asynchronously copies data from the source to the sink. All
+ * data transfer occurs on the thread corresponding to the given event target.
+ * A null event target is not permitted.
+ *
+ * The copier handles blocking or non-blocking streams transparently.  If a
+ * stream operation returns NS_BASE_STREAM_WOULD_BLOCK, then the stream will
+ * be QI'd to nsIAsync{In,Out}putStream and its AsyncWait method will be used
+ * to determine when to resume copying.
+ *
+ * Source and sink are closed by default when copying finishes or when error
+ * occurs. Caller can prevent closing source or sink by setting aCloseSource
+ * or aCloseSink to false.
+ *
+ * Caller can obtain aCopierCtx to be able to cancel copying.
+ */
+extern nsresult
+NS_AsyncCopy(nsIInputStream* aSource,
+             nsIOutputStream* aSink,
+             nsIEventTarget* aTarget,
+             nsAsyncCopyMode aMode = NS_ASYNCCOPY_VIA_READSEGMENTS,
+             uint32_t aChunkSize = 4096,
+             nsAsyncCopyCallbackFun aCallbackFun = nullptr,
+             void* aCallbackClosure = nullptr,
+             bool aCloseSource = true,
+             bool aCloseSink = true,
+             nsISupports** aCopierCtx = nullptr,
+             nsAsyncCopyProgressFun aProgressCallbackFun = nullptr);
+
+/**
+ * This function cancels copying started by function NS_AsyncCopy.
+ *
+ * @param aCopierCtx
+ *        Copier context returned by NS_AsyncCopy.
+ * @param aReason
+ *        A failure code indicating why the operation is being canceled.
+ *        It is an error to pass a success code.
+ */
+extern nsresult
+NS_CancelAsyncCopy(nsISupports* aCopierCtx, nsresult aReason);
+
+/**
+ * This function copies all of the available data from the stream (up to at
+ * most aMaxCount bytes) into the given buffer.  The buffer is truncated at
+ * the start of the function.
+ *
+ * If an error occurs while reading from the stream or while attempting to
+ * resize the buffer, then the corresponding error code is returned from this
+ * function, and any data that has already been read will be returned in the
+ * output buffer.  This allows one to use this function with a non-blocking
+ * input stream that may return NS_BASE_STREAM_WOULD_BLOCK if it only has
+ * partial data available.
+ *
+ * @param aSource
+ *        The input stream to read.
+ * @param aMaxCount
+ *        The maximum number of bytes to consume from the stream.  Pass the
+ *        value UINT32_MAX to consume the entire stream.  The number of
+ *        bytes actually read is given by the length of aBuffer upon return.
+ * @param aBuffer
+ *        The string object that will contain the stream data upon return.
+ *        Note: The data copied to the string may contain null bytes and may
+ *        contain non-ASCII values.
+ */
+extern nsresult
+NS_ConsumeStream(nsIInputStream* aSource, uint32_t aMaxCount,
+                 nsACString& aBuffer);
+
+/**
+ * This function tests whether or not the input stream is buffered. A buffered
+ * input stream is one that implements readSegments.  The test for this is to
+ * 1/ check whether the input stream implements nsIBufferedInputStream;
+ * 2/ if not, call readSegments, without actually consuming any data from the
+ * stream, to verify that it functions.
+ *
+ * NOTE: If the stream is non-blocking and has no data available yet, then this
+ * test will fail.  In that case, we return false even though the test is not
+ * really conclusive.
+ *
+ * PERFORMANCE NOTE: If the stream does not implement nsIBufferedInputStream,
+ * calling readSegments may cause I/O. Therefore, you should avoid calling
+ * this function from the main thread.
+ *
+ * @param aInputStream
+ *        The input stream to test.
+ */
+extern bool
+NS_InputStreamIsBuffered(nsIInputStream* aInputStream);
+
+/**
+ * This function tests whether or not the output stream is buffered.  A
+ * buffered output stream is one that implements writeSegments.  The test for
+ * this is to:
+ * 1/ check whether the output stream implements nsIBufferedOutputStream;
+ * 2/ if not, call writeSegments, without actually writing any data into
+ * the stream, to verify that it functions.
+ *
+ * NOTE: If the stream is non-blocking and has no available space yet, then
+ * this test will fail.  In that case, we return false even though the test is
+ * not really conclusive.
+ *
+ * PERFORMANCE NOTE: If the stream does not implement nsIBufferedOutputStream,
+ * calling writeSegments may cause I/O. Therefore, you should avoid calling
+ * this function from the main thread.
+ *
+ * @param aOutputStream
+ *        The output stream to test.
+ */
+extern bool
+NS_OutputStreamIsBuffered(nsIOutputStream* aOutputStream);
+
+/**
+ * This function is intended to be passed to nsIInputStream::ReadSegments to
+ * copy data from the nsIInputStream into a nsIOutputStream passed as the
+ * aClosure parameter to the ReadSegments function.
+ *
+ * @see nsIInputStream.idl for a description of this function's parameters.
+ */
+extern nsresult
+NS_CopySegmentToStream(nsIInputStream* aInputStream, void* aClosure,
+                       const char* aFromSegment, uint32_t aToOffset,
+                       uint32_t aCount, uint32_t* aWriteCount);
+
+/**
+ * This function is intended to be passed to nsIInputStream::ReadSegments to
+ * copy data from the nsIInputStream into a character buffer passed as the
+ * aClosure parameter to the ReadSegments function.  The character buffer
+ * must be at least as large as the aCount parameter passed to ReadSegments.
+ *
+ * @see nsIInputStream.idl for a description of this function's parameters.
+ */
+extern nsresult
+NS_CopySegmentToBuffer(nsIInputStream* aInputStream, void* aClosure,
+                       const char* aFromSegment, uint32_t aToOffset,
+                       uint32_t aCount, uint32_t* aWriteCount);
+
+/**
+ * This function is intended to be passed to nsIOutputStream::WriteSegments to
+ * copy data into the nsIOutputStream from a character buffer passed as the
+ * aClosure parameter to the WriteSegments function.
+ *
+ * @see nsIOutputStream.idl for a description of this function's parameters.
+ */
+extern nsresult
+NS_CopySegmentToBuffer(nsIOutputStream* aOutputStream, void* aClosure,
+                       char* aToSegment, uint32_t aFromOffset,
+                       uint32_t aCount, uint32_t* aReadCount);
+
+/**
+ * This function is intended to be passed to nsIInputStream::ReadSegments to
+ * discard data from the nsIInputStream.  This can be used to efficiently read
+ * data from the stream without actually copying any bytes.
+ *
+ * @see nsIInputStream.idl for a description of this function's parameters.
+ */
+extern nsresult
+NS_DiscardSegment(nsIInputStream* aInputStream, void* aClosure,
+                  const char* aFromSegment, uint32_t aToOffset,
+                  uint32_t aCount, uint32_t* aWriteCount);
+
+/**
+ * This function is intended to be passed to nsIInputStream::ReadSegments to
+ * adjust the aInputStream parameter passed to a consumer's WriteSegmentFun.
+ * The aClosure parameter must be a pointer to a nsWriteSegmentThunk object.
+ * The mStream and mClosure members of that object will be passed to the mFun
+ * function, with the remainder of the parameters being what are passed to
+ * NS_WriteSegmentThunk.
+ *
+ * This function comes in handy when implementing ReadSegments in terms of an
+ * inner stream's ReadSegments.
+ */
+extern nsresult
+NS_WriteSegmentThunk(nsIInputStream* aInputStream, void* aClosure,
+                     const char* aFromSegment, uint32_t aToOffset,
+                     uint32_t aCount, uint32_t* aWriteCount);
+
+struct MOZ_STACK_CLASS nsWriteSegmentThunk
+{
+  nsCOMPtr<nsIInputStream> mStream;
+  nsWriteSegmentFun mFun;
+  void* mClosure;
+};
+
+/**
+ * Read data from aInput and store in aDest.  A non-zero aKeep will keep that
+ * many bytes from aDest (from the end).  New data is appended after the kept
+ * bytes (if any).  aDest's new length on returning from this function is
+ * aKeep + aNewBytes and is guaranteed to be less than or equal to aDest's
+ * current capacity.
+ * @param aDest the array to fill
+ * @param aInput the stream to read from
+ * @param aKeep number of bytes to keep (0 <= aKeep <= aDest.Length())
+ * @param aNewBytes (out) number of bytes read from aInput or zero if Read()
+ *        failed
+ * @return the result from aInput->Read(...)
+ */
+extern nsresult
+NS_FillArray(FallibleTArray<char>& aDest, nsIInputStream* aInput,
+             uint32_t aKeep, uint32_t* aNewBytes);
+
+/**
+ * Return true if the given stream can be directly cloned.
+ */
+extern bool
+NS_InputStreamIsCloneable(nsIInputStream* aSource);
+
+/**
+ * Clone the provided source stream in the most efficient way possible.  This
+ * first attempts to QI to nsICloneableInputStream to use Clone().  If that is
+ * not supported or its cloneable attribute is false, then a fallback clone is
+ * provided by copying the source to a pipe.  In this case the caller must
+ * replace the source stream with the resulting replacement stream.  The clone
+ * and the replacement stream are then cloneable using nsICloneableInputStream
+ * without duplicating memory.  This fallback clone using the pipe is only
+ * performed if a replacement stream parameter is also passed in.
+ * @param aSource         The input stream to clone.
+ * @param aCloneOut       Required out parameter to hold resulting clone.
+ * @param aReplacementOut Optional out parameter to hold stream to replace
+ *                        original source stream after clone.  If not
+ *                        provided then the fallback clone process is not
+ *                        supported and a non-cloneable source will result
+ *                        in failure.  Replacement streams are non-blocking.
+ * @return NS_OK on successful clone.  Error otherwise.
+ */
+extern nsresult
+NS_CloneInputStream(nsIInputStream* aSource, nsIInputStream** aCloneOut,
+                    nsIInputStream** aReplacementOut = nullptr);
+
+#endif // !nsStreamUtils_h__
diff --git a/xpcom/io/nsStringStream.cpp b/xpcom/io/nsStringStream.cpp
new file mode 100644
index 000000000..b65242c14
--- /dev/null
+++ b/xpcom/io/nsStringStream.cpp
@@ -0,0 +1,452 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * Based on original code from nsIStringStream.cpp
+ */
+
+#include "ipc/IPCMessageUtils.h"
+
+#include "nsStringStream.h"
+#include "nsStreamUtils.h"
+#include "nsReadableUtils.h"
+#include "nsICloneableInputStream.h"
+#include "nsISeekableStream.h"
+#include "nsISupportsPrimitives.h"
+#include "nsCRT.h"
+#include "prerror.h"
+#include "plstr.h"
+#include "nsIClassInfoImpl.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/ipc/InputStreamUtils.h"
+#include "nsIIPCSerializableInputStream.h"
+
+using namespace mozilla::ipc;
+using mozilla::Maybe;
+using mozilla::Some;
+
+//-----------------------------------------------------------------------------
+// nsIStringInputStream implementation
+//-----------------------------------------------------------------------------
+
+class nsStringInputStream final
+  : public nsIStringInputStream
+  , public nsISeekableStream
+  , public nsISupportsCString
+  , public nsIIPCSerializableInputStream
+  , public nsICloneableInputStream
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIINPUTSTREAM
+  NS_DECL_NSISTRINGINPUTSTREAM
+  NS_DECL_NSISEEKABLESTREAM
+  NS_DECL_NSISUPPORTSPRIMITIVE
+  NS_DECL_NSISUPPORTSCSTRING
+  NS_DECL_NSIIPCSERIALIZABLEINPUTSTREAM
+  NS_DECL_NSICLONEABLEINPUTSTREAM
+
+  nsStringInputStream()
+  {
+    Clear();
+  }
+
+  explicit nsStringInputStream(const nsStringInputStream& aOther)
+    : mOffset(aOther.mOffset)
+  {
+    // Use Assign() here because we don't want the life of the clone to be
+    // dependent on the life of the original stream.
+    mData.Assign(aOther.mData);
+  }
+
+private:
+  ~nsStringInputStream()
+  {
+  }
+
+  uint32_t Length() const
+  {
+    return mData.Length();
+  }
+
+  uint32_t LengthRemaining() const
+  {
+    return Length() - mOffset;
+  }
+
+  void Clear()
+  {
+    mData.SetIsVoid(true);
+  }
+
+  bool Closed()
+  {
+    return mData.IsVoid();
+  }
+
+  nsDependentCSubstring mData;
+  uint32_t mOffset;
+};
+
+// This class needs to support threadsafe refcounting since people often
+// allocate a string stream, and then read it from a background thread.
+NS_IMPL_ADDREF(nsStringInputStream)
+NS_IMPL_RELEASE(nsStringInputStream)
+
+NS_IMPL_CLASSINFO(nsStringInputStream, nullptr, nsIClassInfo::THREADSAFE,
+                  NS_STRINGINPUTSTREAM_CID)
+NS_IMPL_QUERY_INTERFACE_CI(nsStringInputStream,
+                           nsIStringInputStream,
+                           nsIInputStream,
+                           nsISupportsCString,
+                           nsISeekableStream,
+                           nsIIPCSerializableInputStream,
+                           nsICloneableInputStream)
+NS_IMPL_CI_INTERFACE_GETTER(nsStringInputStream,
+                            nsIStringInputStream,
+                            nsIInputStream,
+                            nsISupportsCString,
+                            nsISeekableStream,
+                            nsICloneableInputStream)
+
+/////////
+// nsISupportsCString implementation
+/////////
+
+NS_IMETHODIMP
+nsStringInputStream::GetType(uint16_t* aType)
+{
+  *aType = TYPE_CSTRING;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStringInputStream::GetData(nsACString& data)
+{
+  // The stream doesn't have any data when it is closed.  We could fake it
+  // and return an empty string here, but it seems better to keep this return
+  // value consistent with the behavior of the other 'getter' methods.
+  if (NS_WARN_IF(Closed())) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  data.Assign(mData);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStringInputStream::SetData(const nsACString& aData)
+{
+  mData.Assign(aData);
+  mOffset = 0;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStringInputStream::ToString(char** aResult)
+{
+  // NOTE: This method may result in data loss, so we do not implement it.
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+/////////
+// nsIStringInputStream implementation
+/////////
+
+NS_IMETHODIMP
+nsStringInputStream::SetData(const char* aData, int32_t aDataLen)
+{
+  if (NS_WARN_IF(!aData)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  mData.Assign(aData, aDataLen);
+  mOffset = 0;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStringInputStream::AdoptData(char* aData, int32_t aDataLen)
+{
+  if (NS_WARN_IF(!aData)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  mData.Adopt(aData, aDataLen);
+  mOffset = 0;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStringInputStream::ShareData(const char* aData, int32_t aDataLen)
+{
+  if (NS_WARN_IF(!aData)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  if (aDataLen < 0) {
+    aDataLen = strlen(aData);
+  }
+
+  mData.Rebind(aData, aDataLen);
+  mOffset = 0;
+  return NS_OK;
+}
+
+NS_IMETHODIMP_(size_t)
+nsStringInputStream::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf)
+{
+  size_t n = aMallocSizeOf(this);
+  n += mData.SizeOfExcludingThisIfUnshared(aMallocSizeOf);
+  return n;
+}
+
+/////////
+// nsIInputStream implementation
+/////////
+
+NS_IMETHODIMP
+nsStringInputStream::Close()
+{
+  Clear();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStringInputStream::Available(uint64_t* aLength)
+{
+  NS_ASSERTION(aLength, "null ptr");
+
+  if (Closed()) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  *aLength = LengthRemaining();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStringInputStream::Read(char* aBuf, uint32_t aCount, uint32_t* aReadCount)
+{
+  NS_ASSERTION(aBuf, "null ptr");
+  return ReadSegments(NS_CopySegmentToBuffer, aBuf, aCount, aReadCount);
+}
+
+NS_IMETHODIMP
+nsStringInputStream::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
+                                  uint32_t aCount, uint32_t* aResult)
+{
+  NS_ASSERTION(aResult, "null ptr");
+  NS_ASSERTION(Length() >= mOffset, "bad stream state");
+
+  if (Closed()) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  // We may be at end-of-file
+  uint32_t maxCount = LengthRemaining();
+  if (maxCount == 0) {
+    *aResult = 0;
+    return NS_OK;
+  }
+
+  if (aCount > maxCount) {
+    aCount = maxCount;
+  }
+  nsresult rv = aWriter(this, aClosure, mData.BeginReading() + mOffset, 0,
+                        aCount, aResult);
+  if (NS_SUCCEEDED(rv)) {
+    NS_ASSERTION(*aResult <= aCount,
+                 "writer should not write more than we asked it to write");
+    mOffset += *aResult;
+  }
+
+  // errors returned from the writer end here!
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStringInputStream::IsNonBlocking(bool* aNonBlocking)
+{
+  *aNonBlocking = true;
+  return NS_OK;
+}
+
+/////////
+// nsISeekableStream implementation
+/////////
+
+NS_IMETHODIMP
+nsStringInputStream::Seek(int32_t aWhence, int64_t aOffset)
+{
+  if (Closed()) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  // Compute new stream position.  The given offset may be a negative value.
+
+  int64_t newPos = aOffset;
+  switch (aWhence) {
+    case NS_SEEK_SET:
+      break;
+    case NS_SEEK_CUR:
+      newPos += mOffset;
+      break;
+    case NS_SEEK_END:
+      newPos += Length();
+      break;
+    default:
+      NS_ERROR("invalid aWhence");
+      return NS_ERROR_INVALID_ARG;
+  }
+
+  if (NS_WARN_IF(newPos < 0) || NS_WARN_IF(newPos > Length())) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  mOffset = (uint32_t)newPos;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStringInputStream::Tell(int64_t* aOutWhere)
+{
+  if (Closed()) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  *aOutWhere = mOffset;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStringInputStream::SetEOF()
+{
+  if (Closed()) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  mOffset = Length();
+  return NS_OK;
+}
+
+/////////
+// nsIIPCSerializableInputStream implementation
+/////////
+
+void
+nsStringInputStream::Serialize(InputStreamParams& aParams,
+                               FileDescriptorArray& /* aFDs */)
+{
+  StringInputStreamParams params;
+  params.data() = PromiseFlatCString(mData);
+  aParams = params;
+}
+
+bool
+nsStringInputStream::Deserialize(const InputStreamParams& aParams,
+                                 const FileDescriptorArray& /* aFDs */)
+{
+  if (aParams.type() != InputStreamParams::TStringInputStreamParams) {
+    NS_ERROR("Received unknown parameters from the other process!");
+    return false;
+  }
+
+  const StringInputStreamParams& params =
+    aParams.get_StringInputStreamParams();
+
+  if (NS_FAILED(SetData(params.data()))) {
+    NS_WARNING("SetData failed!");
+    return false;
+  }
+
+  return true;
+}
+
+Maybe<uint64_t>
+nsStringInputStream::ExpectedSerializedLength()
+{
+  return Some(static_cast<uint64_t>(Length()));
+}
+
+/////////
+// nsICloneableInputStream implementation
+/////////
+
+NS_IMETHODIMP
+nsStringInputStream::GetCloneable(bool* aCloneableOut)
+{
+  *aCloneableOut = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStringInputStream::Clone(nsIInputStream** aCloneOut)
+{
+  RefPtr<nsIInputStream> ref = new nsStringInputStream(*this);
+  ref.forget(aCloneOut);
+  return NS_OK;
+}
+
+nsresult
+NS_NewByteInputStream(nsIInputStream** aStreamResult,
+                      const char* aStringToRead, int32_t aLength,
+                      nsAssignmentType aAssignment)
+{
+  NS_PRECONDITION(aStreamResult, "null out ptr");
+
+  RefPtr<nsStringInputStream> stream = new nsStringInputStream();
+
+  nsresult rv;
+  switch (aAssignment) {
+    case NS_ASSIGNMENT_COPY:
+      rv = stream->SetData(aStringToRead, aLength);
+      break;
+    case NS_ASSIGNMENT_DEPEND:
+      rv = stream->ShareData(aStringToRead, aLength);
+      break;
+    case NS_ASSIGNMENT_ADOPT:
+      rv = stream->AdoptData(const_cast<char*>(aStringToRead), aLength);
+      break;
+    default:
+      NS_ERROR("invalid assignment type");
+      rv = NS_ERROR_INVALID_ARG;
+  }
+
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  stream.forget(aStreamResult);
+  return NS_OK;
+}
+
+nsresult
+NS_NewCStringInputStream(nsIInputStream** aStreamResult,
+                         const nsACString& aStringToRead)
+{
+  NS_PRECONDITION(aStreamResult, "null out ptr");
+
+  RefPtr<nsStringInputStream> stream = new nsStringInputStream();
+
+  stream->SetData(aStringToRead);
+
+  stream.forget(aStreamResult);
+  return NS_OK;
+}
+
+// factory method for constructing a nsStringInputStream object
+nsresult
+nsStringInputStreamConstructor(nsISupports* aOuter, REFNSIID aIID,
+                               void** aResult)
+{
+  *aResult = nullptr;
+
+  if (NS_WARN_IF(aOuter)) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+
+  RefPtr<nsStringInputStream> inst = new nsStringInputStream();
+  return inst->QueryInterface(aIID, aResult);
+}
diff --git a/xpcom/io/nsStringStream.h b/xpcom/io/nsStringStream.h
new file mode 100644
index 000000000..8c09530eb
--- /dev/null
+++ b/xpcom/io/nsStringStream.h
@@ -0,0 +1,63 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsStringStream_h__
+#define nsStringStream_h__
+
+#include "nsIStringStream.h"
+#include "nsStringGlue.h"
+#include "nsMemory.h"
+
+/**
+ * Implements:
+ *   nsIStringInputStream
+ *   nsIInputStream
+ *   nsISeekableStream
+ *   nsISupportsCString
+ */
+#define NS_STRINGINPUTSTREAM_CONTRACTID "@mozilla.org/io/string-input-stream;1"
+#define NS_STRINGINPUTSTREAM_CID                     \
+{ /* 0abb0835-5000-4790-af28-61b3ba17c295 */         \
+    0x0abb0835,                                      \
+    0x5000,                                          \
+    0x4790,                                          \
+    {0xaf, 0x28, 0x61, 0xb3, 0xba, 0x17, 0xc2, 0x95} \
+}
+
+/**
+ * Factory method to get an nsInputStream from a byte buffer.  Result will
+ * implement nsIStringInputStream and nsISeekableStream.
+ *
+ * If aAssignment is NS_ASSIGNMENT_COPY, then the resulting stream holds a copy
+ * of the given buffer (aStringToRead), and the caller is free to discard
+ * aStringToRead after this function returns.
+ *
+ * If aAssignment is NS_ASSIGNMENT_DEPEND, then the resulting stream refers
+ * directly to the given buffer (aStringToRead), so the caller must ensure that
+ * the buffer remains valid for the lifetime of the stream object.  Use with
+ * care!!
+ *
+ * If aAssignment is NS_ASSIGNMENT_ADOPT, then the resulting stream refers
+ * directly to the given buffer (aStringToRead) and will free aStringToRead
+ * once the stream is closed.
+ *
+ * If aLength is less than zero, then the length of aStringToRead will be
+ * determined by scanning the buffer for the first null byte.
+ */
+extern nsresult
+NS_NewByteInputStream(nsIInputStream** aStreamResult,
+                      const char* aStringToRead, int32_t aLength = -1,
+                      nsAssignmentType aAssignment = NS_ASSIGNMENT_DEPEND);
+
+/**
+ * Factory method to get an nsInputStream from an nsACString.  Result will
+ * implement nsIStringInputStream and nsISeekableStream.
+ */
+extern nsresult
+NS_NewCStringInputStream(nsIInputStream** aStreamResult,
+                         const nsACString& aStringToRead);
+
+#endif // nsStringStream_h__
diff --git a/xpcom/io/nsUnicharInputStream.cpp b/xpcom/io/nsUnicharInputStream.cpp
new file mode 100644
index 000000000..27c074c09
--- /dev/null
+++ b/xpcom/io/nsUnicharInputStream.cpp
@@ -0,0 +1,398 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsUnicharInputStream.h"
+#include "nsIInputStream.h"
+#include "nsIServiceManager.h"
+#include "nsString.h"
+#include "nsTArray.h"
+#include "nsAutoPtr.h"
+#include "nsCRT.h"
+#include "nsStreamUtils.h"
+#include "nsUTF8Utils.h"
+#include "mozilla/Attributes.h"
+#include <fcntl.h>
+#if defined(XP_WIN)
+#include <io.h>
+#else
+#include <unistd.h>
+#endif
+
+#define STRING_BUFFER_SIZE 8192
+
+class StringUnicharInputStream final : public nsIUnicharInputStream
+{
+public:
+  explicit StringUnicharInputStream(const nsAString& aString) :
+    mString(aString), mPos(0), mLen(aString.Length()) { }
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIUNICHARINPUTSTREAM
+
+  nsString mString;
+  uint32_t mPos;
+  uint32_t mLen;
+
+private:
+  ~StringUnicharInputStream() { }
+};
+
+NS_IMETHODIMP
+StringUnicharInputStream::Read(char16_t* aBuf,
+                               uint32_t aCount,
+                               uint32_t* aReadCount)
+{
+  if (mPos >= mLen) {
+    *aReadCount = 0;
+    return NS_OK;
+  }
+  nsAString::const_iterator iter;
+  mString.BeginReading(iter);
+  const char16_t* us = iter.get();
+  uint32_t amount = mLen - mPos;
+  if (amount > aCount) {
+    amount = aCount;
+  }
+  memcpy(aBuf, us + mPos, sizeof(char16_t) * amount);
+  mPos += amount;
+  *aReadCount = amount;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+StringUnicharInputStream::ReadSegments(nsWriteUnicharSegmentFun aWriter,
+                                       void* aClosure,
+                                       uint32_t aCount, uint32_t* aReadCount)
+{
+  uint32_t bytesWritten;
+  uint32_t totalBytesWritten = 0;
+
+  nsresult rv;
+  aCount = XPCOM_MIN(mString.Length() - mPos, aCount);
+
+  nsAString::const_iterator iter;
+  mString.BeginReading(iter);
+
+  while (aCount) {
+    rv = aWriter(this, aClosure, iter.get() + mPos,
+                 totalBytesWritten, aCount, &bytesWritten);
+
+    if (NS_FAILED(rv)) {
+      // don't propagate errors to the caller
+      break;
+    }
+
+    aCount -= bytesWritten;
+    totalBytesWritten += bytesWritten;
+    mPos += bytesWritten;
+  }
+
+  *aReadCount = totalBytesWritten;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+StringUnicharInputStream::ReadString(uint32_t aCount, nsAString& aString,
+                                     uint32_t* aReadCount)
+{
+  if (mPos >= mLen) {
+    *aReadCount = 0;
+    return NS_OK;
+  }
+  uint32_t amount = mLen - mPos;
+  if (amount > aCount) {
+    amount = aCount;
+  }
+  aString = Substring(mString, mPos, amount);
+  mPos += amount;
+  *aReadCount = amount;
+  return NS_OK;
+}
+
+nsresult
+StringUnicharInputStream::Close()
+{
+  mPos = mLen;
+  return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS(StringUnicharInputStream, nsIUnicharInputStream)
+
+//----------------------------------------------------------------------
+
+class UTF8InputStream final : public nsIUnicharInputStream
+{
+public:
+  UTF8InputStream();
+  nsresult Init(nsIInputStream* aStream);
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIUNICHARINPUTSTREAM
+
+private:
+  ~UTF8InputStream();
+
+protected:
+  int32_t Fill(nsresult* aErrorCode);
+
+  static void CountValidUTF8Bytes(const char* aBuf, uint32_t aMaxBytes,
+                                  uint32_t& aValidUTF8bytes,
+                                  uint32_t& aValidUTF16CodeUnits);
+
+  nsCOMPtr<nsIInputStream> mInput;
+  FallibleTArray<char> mByteData;
+  FallibleTArray<char16_t> mUnicharData;
+
+  uint32_t mByteDataOffset;
+  uint32_t mUnicharDataOffset;
+  uint32_t mUnicharDataLength;
+};
+
+UTF8InputStream::UTF8InputStream() :
+  mByteDataOffset(0),
+  mUnicharDataOffset(0),
+  mUnicharDataLength(0)
+{
+}
+
+nsresult
+UTF8InputStream::Init(nsIInputStream* aStream)
+{
+  if (!mByteData.SetCapacity(STRING_BUFFER_SIZE, mozilla::fallible) ||
+      !mUnicharData.SetCapacity(STRING_BUFFER_SIZE, mozilla::fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  mInput = aStream;
+
+  return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS(UTF8InputStream, nsIUnicharInputStream)
+
+UTF8InputStream::~UTF8InputStream()
+{
+  Close();
+}
+
+nsresult
+UTF8InputStream::Close()
+{
+  mInput = nullptr;
+  mByteData.Clear();
+  mUnicharData.Clear();
+  return NS_OK;
+}
+
+nsresult
+UTF8InputStream::Read(char16_t* aBuf, uint32_t aCount, uint32_t* aReadCount)
+{
+  NS_ASSERTION(mUnicharDataLength >= mUnicharDataOffset, "unsigned madness");
+  uint32_t readCount = mUnicharDataLength - mUnicharDataOffset;
+  nsresult errorCode;
+  if (0 == readCount) {
+    // Fill the unichar buffer
+    int32_t bytesRead = Fill(&errorCode);
+    if (bytesRead <= 0) {
+      *aReadCount = 0;
+      return errorCode;
+    }
+    readCount = bytesRead;
+  }
+  if (readCount > aCount) {
+    readCount = aCount;
+  }
+  memcpy(aBuf, mUnicharData.Elements() + mUnicharDataOffset,
+         readCount * sizeof(char16_t));
+  mUnicharDataOffset += readCount;
+  *aReadCount = readCount;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+UTF8InputStream::ReadSegments(nsWriteUnicharSegmentFun aWriter,
+                              void* aClosure,
+                              uint32_t aCount, uint32_t* aReadCount)
+{
+  NS_ASSERTION(mUnicharDataLength >= mUnicharDataOffset, "unsigned madness");
+  uint32_t bytesToWrite = mUnicharDataLength - mUnicharDataOffset;
+  nsresult rv = NS_OK;
+  if (0 == bytesToWrite) {
+    // Fill the unichar buffer
+    int32_t bytesRead = Fill(&rv);
+    if (bytesRead <= 0) {
+      *aReadCount = 0;
+      return rv;
+    }
+    bytesToWrite = bytesRead;
+  }
+
+  if (bytesToWrite > aCount) {
+    bytesToWrite = aCount;
+  }
+
+  uint32_t bytesWritten;
+  uint32_t totalBytesWritten = 0;
+
+  while (bytesToWrite) {
+    rv = aWriter(this, aClosure,
+                 mUnicharData.Elements() + mUnicharDataOffset,
+                 totalBytesWritten, bytesToWrite, &bytesWritten);
+
+    if (NS_FAILED(rv)) {
+      // don't propagate errors to the caller
+      break;
+    }
+
+    bytesToWrite -= bytesWritten;
+    totalBytesWritten += bytesWritten;
+    mUnicharDataOffset += bytesWritten;
+  }
+
+  *aReadCount = totalBytesWritten;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+UTF8InputStream::ReadString(uint32_t aCount, nsAString& aString,
+                            uint32_t* aReadCount)
+{
+  NS_ASSERTION(mUnicharDataLength >= mUnicharDataOffset, "unsigned madness");
+  uint32_t readCount = mUnicharDataLength - mUnicharDataOffset;
+  nsresult errorCode;
+  if (0 == readCount) {
+    // Fill the unichar buffer
+    int32_t bytesRead = Fill(&errorCode);
+    if (bytesRead <= 0) {
+      *aReadCount = 0;
+      return errorCode;
+    }
+    readCount = bytesRead;
+  }
+  if (readCount > aCount) {
+    readCount = aCount;
+  }
+  const char16_t* buf = mUnicharData.Elements() + mUnicharDataOffset;
+  aString.Assign(buf, readCount);
+
+  mUnicharDataOffset += readCount;
+  *aReadCount = readCount;
+  return NS_OK;
+}
+
+int32_t
+UTF8InputStream::Fill(nsresult* aErrorCode)
+{
+  if (!mInput) {
+    // We already closed the stream!
+    *aErrorCode = NS_BASE_STREAM_CLOSED;
+    return -1;
+  }
+
+  NS_ASSERTION(mByteData.Length() >= mByteDataOffset, "unsigned madness");
+  uint32_t remainder = mByteData.Length() - mByteDataOffset;
+  mByteDataOffset = remainder;
+  uint32_t nb;
+  *aErrorCode = NS_FillArray(mByteData, mInput, remainder, &nb);
+  if (nb == 0) {
+    // Because we assume a many to one conversion, the lingering data
+    // in the byte buffer must be a partial conversion
+    // fragment. Because we know that we have received no more new
+    // data to add to it, we can't convert it. Therefore, we discard
+    // it.
+    return nb;
+  }
+  NS_ASSERTION(remainder + nb == mByteData.Length(), "bad nb");
+
+  // Now convert as much of the byte buffer to unicode as possible
+  uint32_t srcLen, dstLen;
+  CountValidUTF8Bytes(mByteData.Elements(), remainder + nb, srcLen, dstLen);
+
+  // the number of UCS2 characters should always be <= the number of
+  // UTF8 chars
+  NS_ASSERTION(remainder + nb >= srcLen, "cannot be longer than out buffer");
+  NS_ASSERTION(dstLen <= mUnicharData.Capacity(),
+               "Ouch. I would overflow my buffer if I wasn't so careful.");
+  if (dstLen > mUnicharData.Capacity()) {
+    return 0;
+  }
+
+  ConvertUTF8toUTF16 converter(mUnicharData.Elements());
+
+  nsASingleFragmentCString::const_char_iterator start = mByteData.Elements();
+  nsASingleFragmentCString::const_char_iterator end = mByteData.Elements() + srcLen;
+
+  copy_string(start, end, converter);
+  if (converter.Length() != dstLen) {
+    *aErrorCode = NS_BASE_STREAM_BAD_CONVERSION;
+    return -1;
+  }
+
+  mUnicharDataOffset = 0;
+  mUnicharDataLength = dstLen;
+  mByteDataOffset = srcLen;
+
+  return dstLen;
+}
+
+void
+UTF8InputStream::CountValidUTF8Bytes(const char* aBuffer, uint32_t aMaxBytes,
+                                     uint32_t& aValidUTF8bytes,
+                                     uint32_t& aValidUTF16CodeUnits)
+{
+  const char* c = aBuffer;
+  const char* end = aBuffer + aMaxBytes;
+  const char* lastchar = c;  // pre-initialize in case of 0-length buffer
+  uint32_t utf16length = 0;
+  while (c < end && *c) {
+    lastchar = c;
+    utf16length++;
+
+    if (UTF8traits::isASCII(*c)) {
+      c++;
+    } else if (UTF8traits::is2byte(*c)) {
+      c += 2;
+    } else if (UTF8traits::is3byte(*c)) {
+      c += 3;
+    } else if (UTF8traits::is4byte(*c)) {
+      c += 4;
+      utf16length++; // add 1 more because this will be converted to a
+      // surrogate pair.
+    } else if (UTF8traits::is5byte(*c)) {
+      c += 5;
+    } else if (UTF8traits::is6byte(*c)) {
+      c += 6;
+    } else {
+      NS_WARNING("Unrecognized UTF8 string in UTF8InputStream::CountValidUTF8Bytes()");
+      break; // Otherwise we go into an infinite loop.  But what happens now?
+    }
+  }
+  if (c > end) {
+    c = lastchar;
+    utf16length--;
+  }
+
+  aValidUTF8bytes = c - aBuffer;
+  aValidUTF16CodeUnits = utf16length;
+}
+
+nsresult
+NS_NewUnicharInputStream(nsIInputStream* aStreamToWrap,
+                         nsIUnicharInputStream** aResult)
+{
+  *aResult = nullptr;
+
+  // Create converter input stream
+  RefPtr<UTF8InputStream> it = new UTF8InputStream();
+  nsresult rv = it->Init(aStreamToWrap);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  it.forget(aResult);
+  return NS_OK;
+}
diff --git a/xpcom/io/nsUnicharInputStream.h b/xpcom/io/nsUnicharInputStream.h
new file mode 100644
index 000000000..d4631af7e
--- /dev/null
+++ b/xpcom/io/nsUnicharInputStream.h
@@ -0,0 +1,15 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsUnicharInputStream_h__
+#define nsUnicharInputStream_h__
+
+#include "nsIUnicharInputStream.h"
+
+nsresult NS_NewUnicharInputStream(nsIInputStream* aStreamToWrap,
+                                  nsIUnicharInputStream** aResult);
+
+#endif // nsUnicharInputStream_h__
diff --git a/xpcom/io/nsWildCard.cpp b/xpcom/io/nsWildCard.cpp
new file mode 100644
index 000000000..9125cbbb8
--- /dev/null
+++ b/xpcom/io/nsWildCard.cpp
@@ -0,0 +1,481 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* *
+ *
+ *
+ * nsWildCard.cpp: shell-like wildcard match routines
+ *
+ * See nsIZipReader.findEntries documentation in nsIZipReader.idl for
+ * a description of the syntax supported by the routines in this file.
+ *
+ * Rob McCool
+ *
+ */
+
+#include "nsWildCard.h"
+#include "nsXPCOM.h"
+#include "nsCRTGlue.h"
+#include "nsCharTraits.h"
+
+/* -------------------- ASCII-specific character methods ------------------- */
+
+typedef int static_assert_character_code_arrangement['a' > 'A' ? 1 : -1];
+
+template<class T>
+static int
+alpha(T aChar)
+{
+  return ('a' <= aChar && aChar <= 'z') ||
+         ('A' <= aChar && aChar <= 'Z');
+}
+
+template<class T>
+static int
+alphanumeric(T aChar)
+{
+  return ('0' <= aChar && aChar <= '9') || ::alpha(aChar);
+}
+
+template<class T>
+static int
+lower(T aChar)
+{
+  return ('A' <= aChar && aChar <= 'Z') ? aChar + ('a' - 'A') : aChar;
+}
+
+template<class T>
+static int
+upper(T aChar)
+{
+  return ('a' <= aChar && aChar <= 'z') ? aChar - ('a' - 'A') : aChar;
+}
+
+/* ----------------------------- _valid_subexp ---------------------------- */
+
+template<class T>
+static int
+_valid_subexp(const T* aExpr, T aStop1, T aStop2)
+{
+  int x;
+  int nsc = 0;     /* Number of special characters */
+  int np;          /* Number of pipe characters in union */
+  int tld = 0;     /* Number of tilde characters */
+
+  for (x = 0; aExpr[x] && (aExpr[x] != aStop1) && (aExpr[x] != aStop2); ++x) {
+    switch (aExpr[x]) {
+      case '~':
+        if (tld) {              /* at most one exclusion */
+          return INVALID_SXP;
+        }
+        if (aStop1) {           /* no exclusions within unions */
+          return INVALID_SXP;
+        }
+        if (!aExpr[x + 1]) {    /* exclusion cannot be last character */
+          return INVALID_SXP;
+        }
+        if (!x) {               /* exclusion cannot be first character */
+          return INVALID_SXP;
+        }
+        ++tld;
+        MOZ_FALLTHROUGH;
+      case '*':
+      case '?':
+      case '$':
+        ++nsc;
+        break;
+      case '[':
+        ++nsc;
+        if ((!aExpr[++x]) || (aExpr[x] == ']')) {
+          return INVALID_SXP;
+        }
+        for (; aExpr[x] && (aExpr[x] != ']'); ++x) {
+          if (aExpr[x] == '\\' && !aExpr[++x]) {
+            return INVALID_SXP;
+          }
+        }
+        if (!aExpr[x]) {
+          return INVALID_SXP;
+        }
+        break;
+      case '(':
+        ++nsc;
+        if (aStop1) {           /* no nested unions */
+          return INVALID_SXP;
+        }
+        np = -1;
+        do {
+          int t = ::_valid_subexp(&aExpr[++x], T(')'), T('|'));
+          if (t == 0 || t == INVALID_SXP) {
+            return INVALID_SXP;
+          }
+          x += t;
+          if (!aExpr[x]) {
+            return INVALID_SXP;
+          }
+          ++np;
+        } while (aExpr[x] == '|');
+        if (np < 1) { /* must be at least one pipe */
+          return INVALID_SXP;
+        }
+        break;
+      case ')':
+      case ']':
+      case '|':
+        return INVALID_SXP;
+      case '\\':
+        ++nsc;
+        if (!aExpr[++x]) {
+          return INVALID_SXP;
+        }
+        break;
+      default:
+        break;
+    }
+  }
+  if (!aStop1 && !nsc) { /* must be at least one special character */
+    return NON_SXP;
+  }
+  return ((aExpr[x] == aStop1 || aExpr[x] == aStop2) ? x : INVALID_SXP);
+}
+
+
+template<class T>
+int
+NS_WildCardValid_(const T* aExpr)
+{
+  int x = ::_valid_subexp(aExpr, T('\0'), T('\0'));
+  return (x < 0 ? x : VALID_SXP);
+}
+
+int
+NS_WildCardValid(const char* aExpr)
+{
+  return NS_WildCardValid_(aExpr);
+}
+
+int
+NS_WildCardValid(const char16_t* aExpr)
+{
+  return NS_WildCardValid_(aExpr);
+}
+
+/* ----------------------------- _shexp_match ----------------------------- */
+
+
+#define MATCH 0
+#define NOMATCH 1
+#define ABORTED -1
+
+template<class T>
+static int
+_shexp_match(const T* aStr, const T* aExpr, bool aCaseInsensitive,
+             unsigned int aLevel);
+
+/**
+ * Count characters until we reach a NUL character or either of the
+ * two delimiter characters, stop1 or stop2.  If we encounter a bracketed
+ * expression, look only for NUL or ']' inside it.  Do not look for stop1
+ * or stop2 inside it. Return ABORTED if bracketed expression is unterminated.
+ * Handle all escaping.
+ * Return index in input string of first stop found, or ABORTED if not found.
+ * If "dest" is non-nullptr, copy counted characters to it and null terminate.
+ */
+template<class T>
+static int
+_scan_and_copy(const T* aExpr, T aStop1, T aStop2, T* aDest)
+{
+  int sx;     /* source index */
+  T cc;
+
+  for (sx = 0; (cc = aExpr[sx]) && cc != aStop1 && cc != aStop2; ++sx) {
+    if (cc == '\\') {
+      if (!aExpr[++sx]) {
+        return ABORTED;  /* should be impossible */
+      }
+    } else if (cc == '[') {
+      while ((cc = aExpr[++sx]) && cc != ']') {
+        if (cc == '\\' && !aExpr[++sx]) {
+          return ABORTED;
+        }
+      }
+      if (!cc) {
+        return ABORTED;  /* should be impossible */
+      }
+    }
+  }
+  if (aDest && sx) {
+    /* Copy all but the closing delimiter. */
+    memcpy(aDest, aExpr, sx * sizeof(T));
+    aDest[sx] = 0;
+  }
+  return cc ? sx : ABORTED; /* index of closing delimiter */
+}
+
+/* On input, expr[0] is the opening parenthesis of a union.
+ * See if any of the alternatives in the union matches as a pattern.
+ * The strategy is to take each of the alternatives, in turn, and append
+ * the rest of the expression (after the closing ')' that marks the end of
+ * this union) to that alternative, and then see if the resultant expression
+ * matches the input string.  Repeat this until some alternative matches,
+ * or we have an abort.
+ */
+template<class T>
+static int
+_handle_union(const T* aStr, const T* aExpr, bool aCaseInsensitive,
+              unsigned int aLevel)
+{
+  int sx;              /* source index */
+  int cp;              /* source index of closing parenthesis */
+  int count;
+  int ret   = NOMATCH;
+  T* e2;
+
+  /* Find the closing parenthesis that ends this union in the expression */
+  cp = ::_scan_and_copy(aExpr, T(')'), T('\0'), static_cast<T*>(nullptr));
+  if (cp == ABORTED || cp < 4) { /* must be at least "(a|b" before ')' */
+    return ABORTED;
+  }
+  ++cp;                /* now index of char after closing parenthesis */
+  e2 = (T*)moz_xmalloc((1 + nsCharTraits<T>::length(aExpr)) * sizeof(T));
+  if (!e2) {
+    return ABORTED;
+  }
+  for (sx = 1; ; ++sx) {
+    /* Here, aExpr[sx] is one character past the preceding '(' or '|'. */
+    /* Copy everything up to the next delimiter to e2 */
+    count = ::_scan_and_copy(aExpr + sx, T(')'), T('|'), e2);
+    if (count == ABORTED || !count) {
+      ret = ABORTED;
+      break;
+    }
+    sx += count;
+    /* Append everything after closing parenthesis to e2. This is safe. */
+    nsCharTraits<T>::copy(e2 + count, aExpr + cp,
+                          nsCharTraits<T>::length(aExpr + cp) + 1);
+    ret = ::_shexp_match(aStr, e2, aCaseInsensitive, aLevel + 1);
+    if (ret != NOMATCH || !aExpr[sx] || aExpr[sx] == ')') {
+      break;
+    }
+  }
+  free(e2);
+  if (sx < 2) {
+    ret = ABORTED;
+  }
+  return ret;
+}
+
+/* returns 1 if val is in range from start..end, case insensitive. */
+static int
+_is_char_in_range(unsigned char aStart, unsigned char aEnd, unsigned char aVal)
+{
+  char map[256];
+  memset(map, 0, sizeof(map));
+  while (aStart <= aEnd) {
+    map[lower(aStart++)] = 1;
+  }
+  return map[lower(aVal)];
+}
+
+template<class T>
+static int
+_shexp_match(const T* aStr, const T* aExpr, bool aCaseInsensitive,
+             unsigned int aLevel)
+{
+  int x;   /* input string index */
+  int y;   /* expression index */
+  int ret, neg;
+
+  if (aLevel > 20) {    /* Don't let the stack get too deep. */
+    return ABORTED;
+  }
+  for (x = 0, y = 0; aExpr[y]; ++y, ++x) {
+    if (!aStr[x] && aExpr[y] != '$' && aExpr[y] != '*') {
+      return NOMATCH;
+    }
+    switch (aExpr[y]) {
+      case '$':
+        if (aStr[x]) {
+          return NOMATCH;
+        }
+        --x;                 /* we don't want loop to increment x */
+        break;
+      case '*':
+        while (aExpr[++y] == '*') {
+        }
+        if (!aExpr[y]) {
+          return MATCH;
+        }
+        while (aStr[x]) {
+          ret = ::_shexp_match(&aStr[x++], &aExpr[y], aCaseInsensitive,
+                               aLevel + 1);
+          switch (ret) {
+            case NOMATCH:
+              continue;
+            case ABORTED:
+              return ABORTED;
+            default:
+              return MATCH;
+          }
+        }
+        if (aExpr[y] == '$' && aExpr[y + 1] == '\0' && !aStr[x]) {
+          return MATCH;
+        } else {
+          return NOMATCH;
+        }
+      case '[': {
+        T start, end = 0;
+        int i;
+        ++y;
+        neg = (aExpr[y] == '^' && aExpr[y + 1] != ']');
+        if (neg) {
+          ++y;
+        }
+        i = y;
+        start = aExpr[i++];
+        if (start == '\\') {
+          start = aExpr[i++];
+        }
+        if (::alphanumeric(start) && aExpr[i++] == '-') {
+          end = aExpr[i++];
+          if (end == '\\') {
+            end = aExpr[i++];
+          }
+        }
+        if (::alphanumeric(end) && aExpr[i] == ']') {
+          /* This is a range form: a-b */
+          T val = aStr[x];
+          if (end < start) { /* swap them */
+            T tmp = end;
+            end = start;
+            start = tmp;
+          }
+          if (aCaseInsensitive && ::alpha(val)) {
+            val = ::_is_char_in_range((unsigned char)start,
+                                      (unsigned char)end,
+                                      (unsigned char)val);
+            if (neg == val) {
+              return NOMATCH;
+            }
+          } else if (neg != (val < start || val > end)) {
+            return NOMATCH;
+          }
+          y = i;
+        } else {
+          /* Not range form */
+          int matched = 0;
+          for (; aExpr[y] != ']'; ++y) {
+            if (aExpr[y] == '\\') {
+              ++y;
+            }
+            if (aCaseInsensitive) {
+              matched |= (::upper(aStr[x]) == ::upper(aExpr[y]));
+            } else {
+              matched |= (aStr[x] == aExpr[y]);
+            }
+          }
+          if (neg == matched) {
+            return NOMATCH;
+          }
+        }
+      }
+      break;
+      case '(':
+        if (!aExpr[y + 1]) {
+          return ABORTED;
+        }
+        return ::_handle_union(&aStr[x], &aExpr[y], aCaseInsensitive,
+                               aLevel + 1);
+      case '?':
+        break;
+      case ')':
+      case ']':
+      case '|':
+        return ABORTED;
+      case '\\':
+        ++y;
+        MOZ_FALLTHROUGH;
+      default:
+        if (aCaseInsensitive) {
+          if (::upper(aStr[x]) != ::upper(aExpr[y])) {
+            return NOMATCH;
+          }
+        } else {
+          if (aStr[x] != aExpr[y]) {
+            return NOMATCH;
+          }
+        }
+        break;
+    }
+  }
+  return (aStr[x] ? NOMATCH : MATCH);
+}
+
+template<class T>
+static int
+ns_WildCardMatch(const T* aStr, const T* aXp, bool aCaseInsensitive)
+{
+  T* expr = nullptr;
+  int ret = MATCH;
+
+  if (!nsCharTraits<T>::find(aXp, nsCharTraits<T>::length(aXp), T('~'))) {
+    return ::_shexp_match(aStr, aXp, aCaseInsensitive, 0);
+  }
+
+  expr = (T*)moz_xmalloc((nsCharTraits<T>::length(aXp) + 1) * sizeof(T));
+  if (!expr) {
+    return NOMATCH;
+  }
+  memcpy(expr, aXp, (nsCharTraits<T>::length(aXp) + 1) * sizeof(T));
+
+  int x = ::_scan_and_copy(expr, T('~'), T('\0'), static_cast<T*>(nullptr));
+  if (x != ABORTED && expr[x] == '~') {
+    expr[x++] = '\0';
+    ret = ::_shexp_match(aStr, &expr[x], aCaseInsensitive, 0);
+    switch (ret) {
+      case NOMATCH:
+        ret = MATCH;
+        break;
+      case MATCH:
+        ret = NOMATCH;
+        break;
+      default:
+        break;
+    }
+  }
+  if (ret == MATCH) {
+    ret = ::_shexp_match(aStr, expr, aCaseInsensitive, 0);
+  }
+
+  free(expr);
+  return ret;
+}
+
+template<class T>
+int
+NS_WildCardMatch_(const T* aStr, const T* aExpr, bool aCaseInsensitive)
+{
+  int is_valid = NS_WildCardValid(aExpr);
+  switch (is_valid) {
+    case INVALID_SXP:
+      return -1;
+    default:
+      return ::ns_WildCardMatch(aStr, aExpr, aCaseInsensitive);
+  }
+}
+
+int
+NS_WildCardMatch(const char* aStr, const char* aXp, bool aCaseInsensitive)
+{
+  return NS_WildCardMatch_(aStr, aXp, aCaseInsensitive);
+}
+
+int
+NS_WildCardMatch(const char16_t* aStr, const char16_t* aXp,
+                 bool aCaseInsensitive)
+{
+  return NS_WildCardMatch_(aStr, aXp, aCaseInsensitive);
+}
diff --git a/xpcom/io/nsWildCard.h b/xpcom/io/nsWildCard.h
new file mode 100644
index 000000000..a077382bb
--- /dev/null
+++ b/xpcom/io/nsWildCard.h
@@ -0,0 +1,64 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * nsWildCard.h: Defines and prototypes for shell exp. match routines
+ *
+ * See nsIZipReader.findEntries docs in nsIZipReader.idl for a description of
+ * the supported expression syntax.
+ *
+ * Note that the syntax documentation explicitly says the results of certain
+ * expressions are undefined.  This is intentional to require less robustness
+ * in the code.  Regular expression parsing is hard; the smaller the set of
+ * features and interactions this code must support, the easier it is to
+ * ensure it works.
+ *
+ */
+
+#ifndef nsWildCard_h__
+#define nsWildCard_h__
+
+#include "nscore.h"
+
+/* --------------------------- Public routines ---------------------------- */
+
+
+/*
+ * NS_WildCardValid takes a shell expression exp as input. It returns:
+ *
+ *  NON_SXP      if exp is a standard string
+ *  INVALID_SXP  if exp is a shell expression, but invalid
+ *  VALID_SXP    if exp is a valid shell expression
+ */
+
+#define NON_SXP -1
+#define INVALID_SXP -2
+#define VALID_SXP 1
+
+int NS_WildCardValid(const char* aExpr);
+
+int NS_WildCardValid(const char16_t* aExpr);
+
+/* return values for the search routines */
+#define MATCH 0
+#define NOMATCH 1
+#define ABORTED -1
+
+/*
+ * NS_WildCardMatch
+ *
+ * Takes a prevalidated shell expression exp, and a string str.
+ *
+ * Returns 0 on match and 1 on non-match.
+ */
+
+int NS_WildCardMatch(const char* aStr, const char* aExpr,
+                     bool aCaseInsensitive);
+
+int NS_WildCardMatch(const char16_t* aStr, const char16_t* aExpr,
+                     bool aCaseInsensitive);
+
+#endif /* nsWildCard_h__ */
diff --git a/xpcom/libxpt/xptcall/porting.html b/xpcom/libxpt/xptcall/porting.html
new file mode 100644
index 000000000..84465306e
--- /dev/null
+++ b/xpcom/libxpt/xptcall/porting.html
@@ -0,0 +1,17 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<html>
+<head>
+<title>Document Moved!</title>
+</head>
+<body bgcolor = "white">
+<center>The xptcall porting document has been moved to:
+<P>
+<a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/porting.html">http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/porting.html</a>
+<P>
+Please update your links.
+</center>
+</body>
+</html>
\ No newline at end of file
diff --git a/xpcom/libxpt/xptcall/status.html b/xpcom/libxpt/xptcall/status.html
new file mode 100644
index 000000000..ba7fe008f
--- /dev/null
+++ b/xpcom/libxpt/xptcall/status.html
@@ -0,0 +1,17 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<html>
+<head>
+<title>Document Moved!</title>
+</head>
+<body bgcolor = "white">
+<center>The xptcall status document has been moved to:
+<P>
+<a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/status.html">http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/status.html</a>
+<P>
+Please update your links.
+</center>
+</body>
+</html>
diff --git a/xpcom/moz.build b/xpcom/moz.build
new file mode 100644
index 000000000..45a83c5c8
--- /dev/null
+++ b/xpcom/moz.build
@@ -0,0 +1,50 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+with Files('**'):
+    BUG_COMPONENT = ('Core', 'XPCOM')
+
+DIRS += [
+    'idl-parser/xpidl',
+]
+
+DIRS += [
+    'typelib',
+    'string',
+    'glue',
+    'base',
+    'ds',
+    'io',
+    'components',
+    'threads',
+    'reflect',
+    'system',
+    '../chrome',
+    'build',
+]
+
+if CONFIG['OS_ARCH'] == 'WINNT' and CONFIG['MOZ_DEBUG']:
+    DIRS += ['windbgdlg']
+
+TEST_DIRS += [
+    'tests',
+    'rust/nsstring/gtest',
+]
+
+#  Can't build internal xptcall tests that use symbols which are not exported.
+#TEST_DIRS += [
+#    'reflect/xptinfo/tests',
+#    'reflect/xptcall/tests,
+#]
+
+CONFIGURE_DEFINE_FILES += [
+    'xpcom-config.h',
+    'xpcom-private.h',
+]
+
+EXPORTS += [
+    '!xpcom-config.h',
+]
diff --git a/xpcom/reflect/moz.build b/xpcom/reflect/moz.build
new file mode 100644
index 000000000..c04892d00
--- /dev/null
+++ b/xpcom/reflect/moz.build
@@ -0,0 +1,8 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += ['xptinfo', 'xptcall']
+
diff --git a/xpcom/reflect/xptcall/README b/xpcom/reflect/xptcall/README
new file mode 100644
index 000000000..0c401fe88
--- /dev/null
+++ b/xpcom/reflect/xptcall/README
@@ -0,0 +1,6 @@
+see:
+
+http://www.mozilla.org/scriptable/xptcall-faq.html
+and
+http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/porting.html
+
diff --git a/xpcom/reflect/xptcall/genstubs.pl b/xpcom/reflect/xptcall/genstubs.pl
new file mode 100644
index 000000000..16ae2006a
--- /dev/null
+++ b/xpcom/reflect/xptcall/genstubs.pl
@@ -0,0 +1,88 @@
+#!/usr/local/bin/perl
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+# This is used to generate stub entry points. We generate a file to
+# be included in the declaraion and a file to be used for expanding macros
+# to represent the implementation of the stubs.
+
+#
+# if "$entry_count" is ever changed and the .inc files regenerated then
+# the following issues need to be addressed:
+#
+# 1) The current Linux ARM code has a limitation of only having 256-3 stubs,
+#    as a result of the limitations of immediate values in ARM assembly.
+#
+# This number is verified by the IDL parser in xpcom/idl-parser/xpidl.py, as
+# well as in xpcom/reflect/xptinfo/xptiInterfaceInfoManager.cpp, to
+# prevent generating interfaces or loading xpt files that would cause the
+# stubs to run off the entries.
+# If you change this number, please update that location.
+
+# 3 entries are already 'used' by the 3 methods of nsISupports.
+# 3+247+5=255 This should get us in under the Linux ARM limitation
+$entry_count    = 247;
+$sentinel_count = 5;
+
+$decl_name = "xptcstubsdecl.inc";
+$def_name  = "xptcstubsdef.inc";
+
+##
+## Write the declarations include file
+##
+
+die "Can't open $decl_name" if !open(OUTFILE, ">$decl_name");
+
+print OUTFILE "/* generated file - DO NOT EDIT */\n\n";
+print OUTFILE "/* includes ",$entry_count," stub entries, and ",
+              $sentinel_count," sentinel entries */\n\n";
+print OUTFILE "/*\n";
+print OUTFILE "*  declarations of normal stubs...\n";
+print OUTFILE "*  0 is QueryInterface\n";
+print OUTFILE "*  1 is AddRef\n";
+print OUTFILE "*  2 is Release\n";
+print OUTFILE "*/\n";
+print OUTFILE "#if !defined(__ia64) || (!defined(__hpux) && !defined(__linux__) && !defined(__FreeBSD__))\n";
+for($i = 0; $i < $entry_count; $i++) {
+    print OUTFILE "NS_IMETHOD Stub",$i+3,"();\n";
+}
+print OUTFILE "#else\n";
+for($i = 0; $i < $entry_count; $i++) {
+    print OUTFILE "NS_IMETHOD Stub",$i+3,"(uint64_t,uint64_t,\n";
+    print OUTFILE " uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);\n";
+
+}
+print OUTFILE "#endif\n";
+
+print OUTFILE "\n/* declarations of sentinel stubs */\n";
+
+for($i = 0; $i < $sentinel_count; $i++) {
+    print OUTFILE "NS_IMETHOD Sentinel",$i,"();\n";
+}
+close(OUTFILE);
+
+
+##
+## Write the definitions include file. This assumes a macro will be used to
+## expand the entries written...
+##
+
+die "Can't open $def_name" if !open(OUTFILE, ">$def_name");
+
+## Disabled for bug 275004 - followup to fix is Bug 419604
+my $warn_inc_is_generated = 0;
+if ($warn_inc_is_generated) {
+print OUTFILE "/* generated file - DO NOT EDIT */\n\n";
+print OUTFILE "/* includes ",$entry_count," stub entries, and ",
+              $sentinel_count," sentinel entries */\n\n";
+}
+
+for($i = 0; $i < $entry_count; $i++) {
+    print OUTFILE "STUB_ENTRY(",$i+3,")\n";
+}
+
+for($i = 0; $i < $sentinel_count; $i++) {
+    print OUTFILE "SENTINEL_ENTRY(",$i,")\n";
+}
diff --git a/xpcom/reflect/xptcall/md/moz.build b/xpcom/reflect/xptcall/md/moz.build
new file mode 100644
index 000000000..a4b59aaf0
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/moz.build
@@ -0,0 +1,12 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+arch = CONFIG['OS_ARCH']
+
+if arch == 'WINNT':
+    DIRS += ['win32']
+else:
+    DIRS += ['unix']
diff --git a/xpcom/reflect/xptcall/md/test/README b/xpcom/reflect/xptcall/md/test/README
new file mode 100644
index 000000000..04850b2e0
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/test/README
@@ -0,0 +1,6 @@
+These are just simple test programs in which stripped down versions of the
+XPConnect invoke and stubs code can be built and tested as the code is brought
+up on various platforms. These probrams do not test the param sizing and copying
+functionality of the routines. However, they do supply a place where the lowest
+level assembly language code can be developed and debugged in the simplest of
+contexts before it is moved into the real routines.
\ No newline at end of file
diff --git a/xpcom/reflect/xptcall/md/test/clean.bat b/xpcom/reflect/xptcall/md/test/clean.bat
new file mode 100755
index 000000000..f320e222c
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/test/clean.bat
@@ -0,0 +1,5 @@
+@echo off
+echo deleting intermediate files
+if exist *.obj  del *.obj > NUL
+if exist *.ilk  del *.ilk > NUL
+if exist *.pdb  del *.pdb > NUL
\ No newline at end of file
diff --git a/xpcom/reflect/xptcall/md/test/invoke_test.cpp b/xpcom/reflect/xptcall/md/test/invoke_test.cpp
new file mode 100644
index 000000000..068db8b2f
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/test/invoke_test.cpp
@@ -0,0 +1,207 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdio.h>
+
+typedef unsigned nsresult;
+typedef unsigned uint32_t;
+typedef unsigned nsXPCVariant;
+
+
+#if defined(WIN32)
+#define NS_IMETHOD virtual nsresult __stdcall
+#define NS_IMETHODIMP nsresult __stdcall
+#else
+#define NS_IMETHOD virtual nsresult
+#define NS_IMETHODIMP nsresult
+#endif
+
+
+class base{
+public:
+  NS_IMETHOD ignored() = 0;
+};
+
+class foo : public base {
+public:
+  NS_IMETHOD callme1(int i, int j) = 0;
+  NS_IMETHOD callme2(int i, int j) = 0;
+  NS_IMETHOD callme3(int i, int j) = 0;
+};
+
+class bar : public foo{
+public:
+  NS_IMETHOD ignored();
+  NS_IMETHOD callme1(int i, int j);
+  NS_IMETHOD callme2(int i, int j);
+  NS_IMETHOD callme3(int i, int j);
+};
+
+/*
+class baz : public base {
+public:
+  NS_IMETHOD ignored();
+  NS_IMETHOD callme1();
+  NS_IMETHOD callme2();
+  NS_IMETHOD callme3();
+  void setfoo(foo* f) {other = f;}
+
+  foo* other;
+};
+NS_IMETHODIMP baz::ignored(){return 0;}
+*/
+
+NS_IMETHODIMP bar::ignored(){return 0;}
+
+NS_IMETHODIMP bar::callme1(int i, int j)
+{
+  printf("called bar::callme1 with: %d %d\n", i, j);
+  return 5;
+}
+
+NS_IMETHODIMP bar::callme2(int i, int j)
+{
+  printf("called bar::callme2 with: %d %d\n", i, j);
+  return 5;
+}
+
+NS_IMETHODIMP bar::callme3(int i, int j)
+{
+  printf("called bar::callme3 with: %d %d\n", i, j);
+  return 5;
+}
+
+void docall(foo* f, int i, int j){
+  f->callme1(i, j); 
+}
+
+/***************************************************************************/
+#if defined(WIN32)
+
+static uint32_t __stdcall
+invoke_count_words(uint32_t paramCount, nsXPCVariant* s)
+{
+    return paramCount;
+}    
+
+static void __stdcall
+invoke_copy_to_stack(uint32_t* d, uint32_t paramCount, nsXPCVariant* s)
+{
+    for(uint32_t i = 0; i < paramCount; i++, d++, s++)
+    {
+        *((uint32_t*)d) = *((uint32_t*)s);
+    }
+}
+
+static nsresult __stdcall
+DoInvoke(void* that, uint32_t index,
+         uint32_t paramCount, nsXPCVariant* params)
+{
+    __asm {
+        push    params
+        push    paramCount
+        call    invoke_count_words  // stdcall, result in eax
+        shl     eax,2               // *= 4
+        sub     esp,eax             // make space for params
+        mov     edx,esp
+        push    params
+        push    paramCount
+        push    edx
+        call    invoke_copy_to_stack // stdcall
+        mov     ecx,that            // instance in ecx
+        push    ecx                 // push this
+        mov     edx,[ecx]           // vtable in edx
+        mov     eax,index
+        shl     eax,2               // *= 4
+        add     edx,eax
+        call    [edx]               // stdcall, i.e. callee cleans up stack.
+    }
+}
+
+#else
+/***************************************************************************/
+// just Linux_x86 now. Add other later...
+
+static uint32_t 
+invoke_count_words(uint32_t paramCount, nsXPCVariant* s)
+{
+    return paramCount;
+}    
+
+static void 
+invoke_copy_to_stack(uint32_t* d, uint32_t paramCount, nsXPCVariant* s)
+{
+    for(uint32_t i = 0; i < paramCount; i++, d++, s++)
+    {
+        *((uint32_t*)d) = *((uint32_t*)s);
+    }
+}
+
+static nsresult
+DoInvoke(void* that, uint32_t index,
+         uint32_t paramCount, nsXPCVariant* params)
+{
+    uint32_t result;
+    void* fn_count = invoke_count_words;
+    void* fn_copy = invoke_copy_to_stack;
+
+ __asm__ __volatile__(
+    "pushl %4\n\t"
+    "pushl %3\n\t"
+    "movl  %5, %%eax\n\t"
+    "call  *%%eax\n\t"       /* count words */
+    "addl  $0x8, %%esp\n\t"
+    "shl   $2, %%eax\n\t"    /* *= 4 */
+    "subl  %%eax, %%esp\n\t" /* make room for params */
+    "movl  %%esp, %%edx\n\t"
+    "pushl %4\n\t"
+    "pushl %3\n\t"
+    "pushl %%edx\n\t"
+    "movl  %6, %%eax\n\t"
+    "call  *%%eax\n\t"       /* copy params */
+    "addl  $0xc, %%esp\n\t"
+    "movl  %1, %%ecx\n\t"
+    "pushl %%ecx\n\t"
+    "movl  (%%ecx), %%edx\n\t"
+    "movl  %2, %%eax\n\t"   /* function index */
+    "shl   $2, %%eax\n\t"   /* *= 4 */
+    "addl  $8, %%eax\n\t"   /* += 8 */
+    "addl  %%eax, %%edx\n\t"
+    "call  *(%%edx)\n\t"    /* safe to not cleanup esp */
+    "movl  %%eax, %0"
+    : "=g" (result)         /* %0 */
+    : "g" (that),           /* %1 */
+      "g" (index),          /* %2 */
+      "g" (paramCount),     /* %3 */
+      "g" (params),         /* %4 */
+      "g" (fn_count),       /* %5 */
+      "g" (fn_copy)         /* %6 */
+    : "ax", "cx", "dx", "memory" 
+    );
+  
+  return result;
+}    
+
+#endif
+/***************************************************************************/
+
+int main()
+{
+  nsXPCVariant params1[2] = {1,2};
+  nsXPCVariant params2[2] = {2,4};
+  nsXPCVariant params3[2] = {3,6};
+
+  foo* a = new bar();
+
+//  printf("calling via C++...\n");
+//  docall(a, 12, 24);
+
+  printf("calling via ASM...\n");
+  DoInvoke(a, 1, 2, params1);
+  DoInvoke(a, 2, 2, params2);
+  DoInvoke(a, 3, 2, params3);
+
+  return 0;
+}
diff --git a/xpcom/reflect/xptcall/md/test/mk_invoke.bat b/xpcom/reflect/xptcall/md/test/mk_invoke.bat
new file mode 100755
index 000000000..10a9be51d
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/test/mk_invoke.bat
@@ -0,0 +1,9 @@
+@echo off
+@echo deleing old output
+if exist invoke_test.obj del invoke_test.obj > NUL
+if exist invoke_test.ilk del invoke_test.ilk > NUL
+if exist *.pdb           del *.pdb           > NUL
+if exist invoke_test.exe del invoke_test.exe > NUL
+
+@echo building...
+cl /nologo -Zi -DWIN32 invoke_test.cpp
\ No newline at end of file
diff --git a/xpcom/reflect/xptcall/md/test/mk_stub.bat b/xpcom/reflect/xptcall/md/test/mk_stub.bat
new file mode 100755
index 000000000..f9af17aff
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/test/mk_stub.bat
@@ -0,0 +1,9 @@
+@echo off
+@echo deleing old output
+if exist stub_test.obj del stub_test.obj > NUL
+if exist stub_test.ilk del stub_test.ilk > NUL
+if exist *.pdb         del *.pdb         > NUL
+if exist stub_test.exe del stub_test.exe > NUL
+
+@echo building...
+cl /nologo -Zi -DWIN32 stub_test.cpp
\ No newline at end of file
diff --git a/xpcom/reflect/xptcall/md/test/moz.build b/xpcom/reflect/xptcall/md/test/moz.build
new file mode 100644
index 000000000..2261c3ce6
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/test/moz.build
@@ -0,0 +1,9 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+SimplePrograms([
+    'stub_test',
+])
diff --git a/xpcom/reflect/xptcall/md/test/stub_test.cpp b/xpcom/reflect/xptcall/md/test/stub_test.cpp
new file mode 100644
index 000000000..6c9559c65
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/test/stub_test.cpp
@@ -0,0 +1,213 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdio.h>
+
+typedef unsigned nsresult;
+typedef unsigned uint32_t;
+typedef unsigned nsXPCVariant;
+
+
+#if defined(WIN32)
+#define NS_IMETHOD virtual nsresult __stdcall
+#define NS_IMETHODIMP nsresult __stdcall
+#else
+#define NS_IMETHOD virtual nsresult
+#define NS_IMETHODIMP nsresult
+#endif
+
+
+class base{
+public:
+  NS_IMETHOD ignored() = 0;
+};
+
+class foo : public base {
+public:
+  NS_IMETHOD callme1(int i, int j) = 0;
+  NS_IMETHOD callme2(int i, int j) = 0;
+  NS_IMETHOD callme3(int i, int j) = 0;
+};
+
+class bar : public foo{
+public:
+  NS_IMETHOD ignored();
+  NS_IMETHOD callme1(int i, int j);
+  NS_IMETHOD callme2(int i, int j);
+  NS_IMETHOD callme3(int i, int j);
+};
+
+class baz : public base {
+public:
+  NS_IMETHOD ignored();
+  NS_IMETHOD callme1();
+  NS_IMETHOD callme2();
+  NS_IMETHOD callme3();
+  void setfoo(foo* f) {other = f;}
+
+  foo* other;
+};
+NS_IMETHODIMP baz::ignored(){return 0;}
+
+NS_IMETHODIMP bar::ignored(){return 0;}
+
+NS_IMETHODIMP bar::callme1(int i, int j)
+{
+  printf("called bar::callme1 with: %d %d\n", i, j);
+  return 15;
+}
+
+NS_IMETHODIMP bar::callme2(int i, int j)
+{
+  printf("called bar::callme2 with: %d %d\n", i, j);
+  return 25;
+}
+
+NS_IMETHODIMP bar::callme3(int i, int j)
+{
+  printf("called bar::callme3 with: %d %d\n", i, j);
+  return 35;
+}
+
+void docall(foo* f, int i, int j){
+  f->callme1(i, j); 
+}
+
+/***************************************************************************/
+#if defined(WIN32)
+
+static int __stdcall
+PrepareAndDispatch(baz* self, uint32_t methodIndex,
+                   uint32_t* args, uint32_t* stackBytesToPop)
+{
+    fprintf(stdout, "PrepareAndDispatch (%p, %d, %p)\n",
+        (void*)self, methodIndex, (void*)args);
+    foo* a = self->other;
+    int p1 = (int) *args;
+    int p2 = (int) *(args+1);
+    int out = 0;
+    switch(methodIndex)
+    {
+    case 1: out = a->callme1(p1, p2); break;
+    case 2: out = a->callme2(p1, p2); break;
+    case 3: out = a->callme3(p1, p2); break;
+    }
+    *stackBytesToPop = 2*4;
+    return out;
+}
+
+#ifndef __GNUC__
+static __declspec(naked) void SharedStub(void)
+{
+    __asm {
+        push ebp            // set up simple stack frame
+        mov  ebp, esp       // stack has: ebp/vtbl_index/retaddr/this/args
+        push ecx            // make room for a ptr
+        lea  eax, [ebp-4]   // pointer to stackBytesToPop
+        push eax
+        lea  ecx, [ebp+16]  // pointer to args
+        push ecx
+        mov  edx, [ebp+4]   // vtbl_index
+        push edx
+        mov  eax, [ebp+12]  // this
+        push eax
+        call PrepareAndDispatch
+        mov  edx, [ebp+8]   // return address
+        mov  ecx, [ebp-4]   // stackBytesToPop
+        add  ecx, 12        // for this, the index, and ret address
+        mov  esp, ebp
+        pop  ebp
+        add  esp, ecx       // fix up stack pointer
+        jmp  edx            // simulate __stdcall return
+    }
+}
+
+// these macros get expanded (many times) in the file #included below
+#define STUB_ENTRY(n) \
+__declspec(naked) nsresult __stdcall baz::callme##n() \
+{ __asm push n __asm jmp SharedStub }
+
+#else /* __GNUC__ */
+
+#define STUB_ENTRY(n) \
+nsresult __stdcall baz::callme##n() \
+{ \
+  uint32_t *args, stackBytesToPop; \
+  int result = 0; \
+  baz *obj; \
+  __asm__ __volatile__ ( \
+    "leal   0x0c(%%ebp), %0\n\t"    /* args */ \
+    "movl   0x08(%%ebp), %1\n\t"    /* this */ \
+    : "=r" (args), \
+      "=r" (obj)); \
+  result = PrepareAndDispatch(obj, n, args,&stackBytesToPop); \
+    fprintf(stdout, "stub returning: %d\n", result); \
+    fprintf(stdout, "bytes to pop:  %d\n", stackBytesToPop); \
+    return result; \
+}
+
+#endif /* ! __GNUC__ */
+
+#else
+/***************************************************************************/
+// just Linux_x86 now. Add other later...
+
+static int
+PrepareAndDispatch(baz* self, uint32_t methodIndex, uint32_t* args)
+{
+    foo* a = self->other;
+    int p1 = (int) *args;
+    int p2 = (int) *(args+1);
+    switch(methodIndex)
+    {
+    case 1: a->callme1(p1, p2); break;
+    case 2: a->callme2(p1, p2); break;
+    case 3: a->callme3(p1, p2); break;
+    }
+    return 1;
+}
+
+#define STUB_ENTRY(n) \
+nsresult baz::callme##n() \
+{ \
+  void* method = PrepareAndDispatch; \
+  nsresult result; \
+  __asm__ __volatile__( \
+    "leal   0x0c(%%ebp), %%ecx\n\t"    /* args */ \
+    "pushl  %%ecx\n\t" \
+    "pushl  $"#n"\n\t"                 /* method index */ \
+    "movl   0x08(%%ebp), %%ecx\n\t"    /* this */ \
+    "pushl  %%ecx\n\t" \
+    "call   *%%edx"                    /* PrepareAndDispatch */ \
+    : "=a" (result)     /* %0 */ \
+    : "d" (method)      /* %1 */ \
+    : "memory" ); \
+    return result; \
+}
+
+#endif
+/***************************************************************************/
+
+STUB_ENTRY(1)
+STUB_ENTRY(2)
+STUB_ENTRY(3)
+
+int main()
+{
+  foo* a = new bar();
+  baz* b = new baz();
+
+  /* here we make the global 'check for alloc failure' checker happy */
+  if(!a || !b)
+    return 1;
+  
+  foo* c = (foo*)b;
+
+  b->setfoo(a);
+  c->callme1(1,2);
+  c->callme2(2,4);
+  c->callme3(3,6);
+
+  return 0;
+}
diff --git a/xpcom/reflect/xptcall/md/unix/Makefile.in b/xpcom/reflect/xptcall/md/unix/Makefile.in
new file mode 100644
index 000000000..e4cdc389b
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/Makefile.in
@@ -0,0 +1,79 @@
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+######################################################################
+# HPPA
+######################################################################
+#
+# HP-UX/PA32
+#
+# for gas and gcc, check comment in xptcinvoke_asm_pa32.s
+ifeq ($(OS_ARCH),HP-UX)
+ifneq ($(CC),gcc)
+# #18875  Building the CPP's (CXX) optimized causes a crash
+CXXFLAGS 	:=  $(filter-out $(MOZ_OPTIMIZE_FLAGS), $(CXXFLAGS))
+endif
+endif
+
+#
+# Linux/HPPA/gcc
+#
+ifeq ($(OS_ARCH),Linux)
+ifneq (,$(filter hppa hppa2.0 hppa1.1,$(OS_TEST)))
+ifndef GNU_CXX
+else
+# #434190 optimized builds crash
+CXXFLAGS 	:=  $(filter-out $(MOZ_OPTIMIZE_FLAGS), $(CXXFLAGS))
+endif
+endif
+endif
+
+
+######################################################################
+# PowerPC
+######################################################################
+#
+# AIX/PPC
+#
+ifeq ($(OS_ARCH),AIX)
+# #24617  Building the CPP's (CXX) optimized causes a crash
+CXXFLAGS 	:=  $(filter-out $(MOZ_OPTIMIZE_FLAGS), $(CXXFLAGS))
+endif
+
+include $(topsrcdir)/config/rules.mk
+
+ifeq ($(OS_ARCH),Linux)
+ifneq (,$(findstring mips, $(OS_TEST)))
+xptcstubs_asm_mips.o: $(DIST)/include/xptcstubsdef.inc
+endif
+endif
+
+ifeq ($(OS_ARCH),Darwin)
+xptcstubs_asm_ppc_darwin.s: xptcstubs_asm_ppc_darwin.s.m4 $(DIST)/include/xptcstubsdef.inc Makefile
+	gm4 $(INCLUDES) $< > $@
+endif
+
+ifeq ($(OS_ARCH),AIX)
+ifdef HAVE_64BIT_BUILD
+xptcstubs_asm_ppc_aix64.s: xptcstubs_asm_ppc_aix64.s.m4 $(DIST)/include/xptcstubsdef.inc Makefile
+	m4 -DAIX_OBJMODEL=$(AIX_OBJMODEL) $(INCLUDES) -I. $< > $@
+else
+xptcstubs_asm_ppc_aix.s: xptcstubs_asm_ppc_aix.s.m4 $(DIST)/include/xptcstubsdef.inc Makefile
+	m4 -DAIX_OBJMODEL=$(AIX_OBJMODEL) $(INCLUDES) -I. $< > $@
+endif
+endif
+
+ifeq ($(OS_ARCH),SunOS)
+ifeq (86,$(findstring 86,$(OS_TEST)))
+ifndef GNU_CC
+xptcstubsdef_asm.solx86: $(DIST)/include/xptcstubsdef.inc
+	sed \
+	  -e 's/^\(STUB_ENTRY\)(\([0-9]\))/\11\(\2\)/' \
+	  -e 's/^\(STUB_ENTRY\)(\([0-9][0-9]\))/\12\(\2\)/' \
+	  -e 's/^\(STUB_ENTRY\)(\([0-9][0-9][0-9]\))/\13\(\2\)/' \
+	$(DIST)/include/xptcstubsdef.inc > $@
+endif
+endif
+endif
diff --git a/xpcom/reflect/xptcall/md/unix/moz.build b/xpcom/reflect/xptcall/md/unix/moz.build
new file mode 100644
index 000000000..1d182bbd6
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/moz.build
@@ -0,0 +1,327 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+if CONFIG['OS_ARCH'] == 'Darwin':
+    SOURCES += [
+        'xptcinvoke_darwin.cpp',
+        'xptcstubs_darwin.cpp',
+    ]
+    if CONFIG['OS_TEST'] == 'powerpc':
+        SOURCES += [
+            '!xptcstubs_asm_ppc_darwin.s',
+            'xptcinvoke_asm_ppc_rhapsody.s',
+        ]
+    if '86' in CONFIG['OS_TEST'] and CONFIG['OS_TEST'] != 'x86_64':
+        DEFINES['MOZ_NEED_LEADING_UNDERSCORE'] = True
+
+if CONFIG['OS_ARCH'] == 'GNU':
+    if CONFIG['CPU_ARCH'] == 'x86':
+        SOURCES += [
+            'xptcinvoke_gcc_x86_unix.cpp',
+            'xptcstubs_gcc_x86_unix.cpp'
+        ]
+
+if CONFIG['OS_ARCH'] in ('Linux', 'Bitrig', 'DragonFly', 'FreeBSD', 'NetBSD', 'OpenBSD') or \
+   CONFIG['OS_ARCH'].startswith('GNU_'):
+    if CONFIG['OS_TEST'] == 'x86_64':
+        SOURCES += [
+            'xptcinvoke_x86_64_unix.cpp',
+            'xptcstubs_x86_64_linux.cpp',
+        ]
+    elif '86' in CONFIG['OS_TEST']:
+        SOURCES += [
+            'xptcinvoke_gcc_x86_unix.cpp',
+            'xptcstubs_gcc_x86_unix.cpp'
+        ]
+
+if CONFIG['OS_ARCH'] in ('Linux', 'FreeBSD'):
+    if 'ia64' in CONFIG['OS_TEST']:
+        SOURCES += [
+            'xptcinvoke_asm_ipf64.s',
+            'xptcinvoke_ipf64.cpp',
+            'xptcstubs_asm_ipf64.s',
+            'xptcstubs_ipf64.cpp'
+        ]
+
+if CONFIG['OS_ARCH'] == 'SunOS' and '86' in CONFIG['OS_TEST']:
+    GENERATED_FILES = [
+        'xptcstubsdef_asm.solx86',
+    ]
+    if CONFIG['OS_TEST'] == 'x86_64':
+        if CONFIG['GNU_CC']:
+            SOURCES += [
+                'xptcinvoke_x86_64_unix.cpp',
+                'xptcstubs_x86_64_linux.cpp'
+            ]
+        else:
+            ASFLAGS += ['-xarch=amd64']
+            SOURCES += [
+                'xptcinvoke_x86_64_solaris.cpp',
+                'xptcstubs_asm_x86_64_solaris_SUNW.s',
+                'xptcstubs_x86_64_solaris.cpp',
+            ]
+    else:
+        if CONFIG['GNU_CC']:
+            SOURCES += [
+                'xptcinvoke_gcc_x86_unix.cpp',
+                'xptcstubs_gcc_x86_unix.cpp'
+            ]
+        else:
+            SOURCES += [
+                'xptcinvoke_asm_x86_solaris_SUNW.s',
+                'xptcinvoke_x86_solaris.cpp',
+                'xptcstubs_asm_x86_solaris_SUNW.s',
+                'xptcstubs_x86_solaris.cpp'
+            ]
+
+if CONFIG['OS_TEST'] == 'alpha':
+    if CONFIG['OS_ARCH'] in ('Linux', 'FreeBSD', 'NetBSD'):
+        SOURCES += [
+            'xptcinvoke_linux_alpha.cpp',
+            'xptcstubs_linux_alpha.cpp',
+        ]
+    elif CONFIG['OS_ARCH'] == 'OpenBSD':
+        SOURCES += [
+            'xptcinvoke_alpha_openbsd.cpp',
+            'xptcstubs_alpha_openbsd.cpp',
+        ]
+
+if CONFIG['CPU_ARCH'] == 'arm' or CONFIG['OS_TEST'] == 'sa110':
+    if CONFIG['OS_ARCH'] == 'Linux':
+        SOURCES += [
+            'xptcinvoke_arm.cpp',
+            'xptcstubs_arm.cpp'
+        ]
+        CXXFLAGS += ['-O2']
+    elif CONFIG['OS_ARCH'] == 'NetBSD':
+        SOURCES += [
+            'xptcinvoke_arm_netbsd.cpp',
+            'xptcstubs_arm_netbsd.cpp',
+        ]
+
+if CONFIG['CPU_ARCH'] == 'arm' and CONFIG['OS_ARCH'] in ('Bitrig', 'OpenBSD'):
+    SOURCES += [
+        'xptcinvoke_arm_openbsd.cpp',
+        'xptcstubs_arm_openbsd.cpp',
+    ]
+
+if CONFIG['OS_ARCH'] == 'HP-UX':
+    if CONFIG['CC'] != 'gcc':
+        if CONFIG['OS_TEST'] == 'ia64':
+            SOURCES += [
+                'xptcinvoke_asm_ipf32.s',
+                'xptcinvoke_ipf32.cpp',
+                'xptcstubs_asm_ipf32.s',
+                'xptcstubs_ipf32.cpp',
+            ]
+        else:
+            SOURCES += [
+                'xptcinvoke_asm_pa32.s',
+                'xptcinvoke_pa32.cpp',
+                'xptcstubs_asm_pa32.s',
+                'xptcstubs_pa32.cpp'
+            ]
+
+if CONFIG['OS_ARCH'] == 'Linux':
+    if CONFIG['OS_TEST'] in ('hppa', 'hppa2.0', 'hppa1.1'):
+        if CONFIG['GNU_CXX']:
+            SOURCES += [
+                'xptcinvoke_asm_parisc_linux.s',
+                'xptcinvoke_pa32.cpp',
+                'xptcstubs_asm_parisc_linux.s',
+                'xptcstubs_pa32.cpp',
+            ]
+        elif CONFIG['COMPILE_ENVIRONMENT']:
+            error('Unknown C++ compiler, xptcall assembly will probably be incorrect.')
+
+if CONFIG['OS_ARCH'] == 'NetBSD':
+    if CONFIG['OS_TEST'] in ('amiga', 'atari', 'hp300', 'mac68k', 'mvme68k',
+                             'next68k', 'sun3', 'sun3x', 'x68k'):
+        SOURCES += [
+            'xptcinvoke_netbsd_m68k.cpp',
+            'xptcstubs_netbsd_m68k.cpp'
+        ]
+
+if CONFIG['OS_ARCH'] in ('Linux', 'FreeBSD', 'NetBSD', 'OpenBSD'):
+    if CONFIG['OS_TEST'] == 'aarch64':
+        SOURCES += [
+            'xptcinvoke_aarch64.cpp',
+            'xptcinvoke_asm_aarch64.s',
+            'xptcstubs_aarch64.cpp',
+            'xptcstubs_asm_aarch64.s',
+        ]
+    if CONFIG['OS_TEST'] == 'm68k':
+        SOURCES += [
+            'xptcinvoke_linux_m68k.cpp',
+            'xptcstubs_linux_m68k.cpp',
+        ]
+    if 'mips' in CONFIG['OS_TEST']:
+        if 'mips64' in CONFIG['OS_TEST']:
+            SOURCES += [
+                'xptcinvoke_asm_mips64.S',
+                'xptcinvoke_mips64.cpp',
+                'xptcstubs_asm_mips64.S',
+                'xptcstubs_mips64.cpp',
+            ]
+        else:
+            SOURCES += [
+                'xptcinvoke_asm_mips.S',
+                'xptcinvoke_mips.cpp',
+                'xptcstubs_asm_mips.S',
+                'xptcstubs_mips.cpp',
+            ]
+
+if CONFIG['OS_ARCH'] == 'AIX':
+    if CONFIG['HAVE_64BIT_BUILD']:
+        SOURCES += [
+            '!xptcstubs_asm_ppc_aix64.s',
+            'xptcinvoke_asm_ppc_aix64.s',
+            'xptcinvoke_ppc_aix64.cpp',
+            'xptcstubs_ppc_aix64.cpp',
+        ]
+    else:
+        SOURCES += [
+            '!xptcstubs_asm_ppc_aix.s',
+            'xptcinvoke_ppc_aix.cpp',
+            'xptcstubs_ppc_aix.cpp',
+        ]
+        if CONFIG['AIX_OBJMODEL'] == 'ibm':
+            SOURCES += [
+                'xptcinvoke_asm_ppc_ibmobj_aix.s',
+            ]
+        else:
+            SOURCES += [
+                'xptcinvoke_asm_ppc_aix.s',
+            ]
+
+if CONFIG['OS_TEST'] == 'powerpc':
+    if CONFIG['OS_ARCH'] in ('Linux', 'FreeBSD'):
+        SOURCES += [
+            'xptcinvoke_asm_ppc_linux.S',
+            'xptcinvoke_ppc_linux.cpp',
+            'xptcstubs_asm_ppc_linux.S',
+            'xptcstubs_ppc_linux.cpp',
+        ]
+
+if CONFIG['OS_TEST'] in ('powerpc64', 'powerpc64le'):
+    if CONFIG['OS_ARCH'] in ('Linux', 'FreeBSD'):
+          SOURCES += [
+              'xptcinvoke_asm_ppc64_linux.S',
+              'xptcinvoke_ppc64_linux.cpp',
+              'xptcstubs_asm_ppc64_linux.S',
+              'xptcstubs_ppc64_linux.cpp',
+          ]
+
+if CONFIG['OS_TEST'] in ('macppc', 'bebox', 'ofppc', 'prep', 'amigappc'):
+    if CONFIG['OS_ARCH'] == 'NetBSD':
+        SOURCES += [
+            'xptcinvoke_asm_ppc_netbsd.s',
+            'xptcinvoke_ppc_netbsd.cpp',
+            'xptcstubs_asm_ppc_netbsd.s',
+            'xptcstubs_ppc_netbsd.cpp',
+        ]
+
+if CONFIG['OS_ARCH'] == 'OpenBSD' and CONFIG['OS_TEST'] == 'powerpc':
+    SOURCES += [
+        'xptcinvoke_asm_ppc_openbsd.S',
+        'xptcinvoke_ppc_openbsd.cpp',
+        'xptcstubs_asm_ppc_openbsd.S',
+        'xptcstubs_ppc_openbsd.cpp',
+    ]
+
+if CONFIG['OS_ARCH'] == 'Linux' and 'sparc' in CONFIG['OS_TEST']:
+    SOURCES += [
+        'xptcinvoke_asm_sparc_linux_GCC3.s',
+        'xptcinvoke_sparc_solaris.cpp',
+        'xptcstubs_asm_sparc_solaris.s',
+        'xptcstubs_sparc_solaris.cpp',
+    ]
+
+if CONFIG['OS_ARCH'] == 'NetBSD' and CONFIG['OS_TEST'] == 'sparc':
+    SOURCES += [
+        'xptcinvoke_asm_sparc_netbsd.s',
+        'xptcinvoke_sparc_netbsd.cpp',
+        'xptcstubs_asm_sparc_netbsd.s',
+        'xptcstubs_sparc_netbsd.cpp',
+    ]
+
+if CONFIG['OS_ARCH'] == 'OpenBSD' and CONFIG['OS_TEST'] == 'sparc':
+    SOURCES += [
+        'xptcinvoke_asm_sparc_openbsd.s',
+        'xptcinvoke_sparc_openbsd.cpp',
+        'xptcstubs_asm_sparc_openbsd.s',
+        'xptcstubs_sparc_openbsd.cpp',
+    ]
+
+if CONFIG['OS_ARCH'] in ('OpenBSD', 'FreeBSD') and CONFIG['OS_TEST'] == 'sparc64':
+    SOURCES += [
+        'xptcinvoke_asm_sparc64_openbsd.s',
+        'xptcinvoke_sparc64_openbsd.cpp',
+        'xptcstubs_asm_sparc64_openbsd.s',
+        'xptcstubs_sparc64_openbsd.cpp',
+    ]
+
+if CONFIG['OS_ARCH'] == 'SunOS' and '86' not in CONFIG['OS_TEST']:
+    if CONFIG['HAVE_64BIT_BUILD']:
+        ASFLAGS += ['-xarch=v9']
+        SOURCES += [
+            'xptcinvoke_sparcv9_solaris.cpp',
+            'xptcstubs_sparcv9_solaris.cpp',
+        ]
+    else:
+        SOURCES += [
+            'xptcinvoke_sparc_solaris.cpp',
+            'xptcstubs_sparc_solaris.cpp',
+        ]
+    if CONFIG['GNU_CC']:
+        SOURCES += [
+            'xptcinvoke_asm_sparc_solaris_GCC3.s',
+            'xptcstubs_asm_sparc_solaris.s',
+        ]
+    else:
+        if CONFIG['HAVE_64BIT_BUILD']:
+            SOURCES += [
+                'xptcinvoke_asm_sparcv9_solaris_SUNW.s',
+                'xptcstubs_asm_sparcv9_solaris.s',
+            ]
+        else:
+            SOURCES += [
+                'xptcinvoke_asm_sparc_solaris_SUNW.s',
+                'xptcstubs_asm_sparc_solaris.s',
+            ]
+
+if CONFIG['OS_ARCH'] == 'Linux':
+    if CONFIG['OS_TEST'] == 's390':
+        SOURCES += [
+            'xptcinvoke_linux_s390.cpp',
+            'xptcstubs_linux_s390.cpp',
+        ]
+        CXXFLAGS += [
+            '-fno-strict-aliasing',
+            '-fno-inline',
+            '-fomit-frame-pointer',
+            '-mbackchain',
+        ]
+    elif CONFIG['OS_TEST'] == 's390x':
+        SOURCES += [
+            'xptcinvoke_linux_s390x.cpp',
+            'xptcstubs_linux_s390x.cpp',
+        ]
+        CXXFLAGS += [
+            '-fno-strict-aliasing',
+            '-fno-inline',
+            '-fomit-frame-pointer',
+            '-mbackchain',
+        ]
+
+FINAL_LIBRARY = 'xul'
+
+LOCAL_INCLUDES += [
+    '../..',
+    '/xpcom/reflect/xptinfo',
+]
+
+NO_PGO = True
diff --git a/xpcom/reflect/xptcall/md/unix/vtable_layout_x86.cpp b/xpcom/reflect/xptcall/md/unix/vtable_layout_x86.cpp
new file mode 100644
index 000000000..0cb327a3d
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/vtable_layout_x86.cpp
@@ -0,0 +1,66 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* this code contributed by Bert Driehuis <bert_driehuis@nl.compuware.com> */
+
+#include <stdio.h>
+
+// Try to determine the vtable layout generated by G++
+// Produces the offset at which the first vtable entry can be
+// found, and the factor to apply for subsequent entries on stdout.
+// Example output:
+//    #define GCC_VTABLE_START        0xc
+//    #define GCC_VTABLE_FACTOR       0x8
+
+class test {
+public:
+      virtual int     t1(void);
+      virtual int     t2(void);
+      int             x;
+};
+
+test::test() { this->x = 0x12121212; };
+
+int test::t1(void) { return 1; }
+int test::t2(void) { return 2; }
+
+void die(char *x) {
+      fprintf(stderr, "%s\n", x);
+      exit(1);
+}
+
+int 
+main()
+{
+      int             i;
+      test           *t = new test();
+      int            *tp = (int *) t;
+      int             off1 = -1;
+      int             off2 = -1;
+      int             factor;
+      int             factorshift;
+
+      if (*tp++ != 0x12121212)
+              die("Integer element test::x not found!");
+      tp = (int *) *tp;
+      for (i = 0; i < 10; i++) {
+              if (tp[i] == (int) t->t1)
+                      off1 = i;
+              if (tp[i] == (int) t->t2)
+                      off2 = i;
+      }
+      if (off1 == -1 || off2 == -1)
+              die("Could not determine offset into vtable!");
+      factor = (off2 - off1) * 4;
+      factorshift = -1;
+      while (factor) {
+              factorshift++;
+              factor >>= 1;
+      }
+      printf("/* Automatically generated by vtable_layout_x86.cpp */\n");
+      printf("#define GCC_VTABLE_START\t0x%x\n", off1 * 4);
+      printf("#define GCC_VTABLE_FACTOR\t0x%x\n", (off2 - off1) * 4);
+      printf("#define GCC_VTABLE_SHIFT\t0x%x\n", factorshift);
+      exit(0);
+}
diff --git a/xpcom/reflect/xptcall/md/unix/xptc_gcc_x86_unix.h b/xpcom/reflect/xptcall/md/unix/xptc_gcc_x86_unix.h
new file mode 100644
index 000000000..733646c49
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptc_gcc_x86_unix.h
@@ -0,0 +1,17 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Special include file for xptc*_gcc_x86_unix.cpp */
+
+// 
+// this may improve the static function calls, but may not.
+//
+
+#ifdef MOZ_NEED_LEADING_UNDERSCORE
+#define SYMBOL_UNDERSCORE "_"
+#else
+#define SYMBOL_UNDERSCORE
+#endif
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_aarch64.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_aarch64.cpp
new file mode 100644
index 000000000..e5807dbcd
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_aarch64.cpp
@@ -0,0 +1,140 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+#if !defined(__aarch64__)
+#error "This code is for Linux AArch64 only."
+#endif
+
+
+/* "Procedure Call Standard for the ARM 64-bit Architecture" document, sections
+ * "5.4 Parameter Passing" and "6.1.2 Procedure Calling" contain all the
+ * needed information.
+ *
+ * http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042d/IHI0042D_aapcs.pdf
+ */
+
+#ifndef __AARCH64EL__
+#error "Only little endian compatibility was tested"
+#endif
+
+/*
+ * Allocation of integer function arguments initially to registers r1-r7
+ * and then to stack. Handling of 'that' argument which goes to register r0
+ * is handled separately and does not belong here.
+ *
+ * 'ireg_args'  - pointer to the current position in the buffer,
+ *                corresponding to the register arguments
+ * 'stack_args' - pointer to the current position in the buffer,
+ *                corresponding to the arguments on stack
+ * 'end'        - pointer to the end of the registers argument
+ *                buffer.
+ */
+static inline void alloc_word(uint64_t* &ireg_args,
+                              uint64_t* &stack_args,
+                              uint64_t* end,
+                              uint64_t  data)
+{
+    if (ireg_args < end) {
+        *ireg_args = data;
+        ireg_args++;
+    } else {
+        *stack_args = data;
+        stack_args++;
+    }
+}
+
+static inline void alloc_double(double* &freg_args,
+                                uint64_t* &stack_args,
+                                double* end,
+                                double  data)
+{
+    if (freg_args < end) {
+        *freg_args = data;
+        freg_args++;
+    } else {
+        memcpy(stack_args, &data, sizeof(data));
+        stack_args++;
+    }
+}
+
+static inline void alloc_float(double* &freg_args,
+                               uint64_t* &stack_args,
+                               double* end,
+                               float  data)
+{
+    if (freg_args < end) {
+        memcpy(freg_args, &data, sizeof(data));
+        freg_args++;
+    } else {
+        memcpy(stack_args, &data, sizeof(data));
+        stack_args++;
+    }
+}
+
+
+extern "C" void
+invoke_copy_to_stack(uint64_t* stk, uint64_t *end,
+                     uint32_t paramCount, nsXPTCVariant* s)
+{
+    uint64_t *ireg_args = stk;
+    uint64_t *ireg_end  = ireg_args + 8;
+    double *freg_args = (double *)ireg_end;
+    double *freg_end  = freg_args + 8;
+    uint64_t *stack_args = (uint64_t *)freg_end;
+
+    // leave room for 'that' argument in x0
+    ++ireg_args;
+
+    for (uint32_t i = 0; i < paramCount; i++, s++) {
+        uint64_t word;
+
+        if (s->IsPtrData()) {
+            word = (uint64_t)s->ptr;
+        } else {
+            // According to the ABI, integral types that are smaller than 8
+            // bytes are to be passed in 8-byte registers or 8-byte stack
+            // slots.
+            switch (s->type) {
+                case nsXPTType::T_FLOAT:
+                    alloc_float(freg_args, stack_args, freg_end, s->val.f);
+                    continue;
+                case nsXPTType::T_DOUBLE:
+                    alloc_double(freg_args, stack_args, freg_end, s->val.d);
+                    continue;
+                case nsXPTType::T_I8:    word = s->val.i8;  break;
+                case nsXPTType::T_I16:   word = s->val.i16; break;
+                case nsXPTType::T_I32:   word = s->val.i32; break;
+                case nsXPTType::T_I64:   word = s->val.i64; break;
+                case nsXPTType::T_U8:    word = s->val.u8;  break;
+                case nsXPTType::T_U16:   word = s->val.u16; break;
+                case nsXPTType::T_U32:   word = s->val.u32; break;
+                case nsXPTType::T_U64:   word = s->val.u64; break;
+                case nsXPTType::T_BOOL:  word = s->val.b;   break;
+                case nsXPTType::T_CHAR:  word = s->val.c;   break;
+                case nsXPTType::T_WCHAR: word = s->val.wc;  break;
+                default:
+                    // all the others are plain pointer types
+                    word = reinterpret_cast<uint64_t>(s->val.p);
+                    break;
+            }
+        }
+
+        alloc_word(ireg_args, stack_args, ireg_end, word);
+    }
+}
+
+extern "C" nsresult _NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                                      uint32_t paramCount, nsXPTCVariant* params);
+
+EXPORT_XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                 uint32_t paramCount, nsXPTCVariant* params)
+{
+    return _NS_InvokeByIndex(that, methodIndex, paramCount, params);
+}
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_alpha_openbsd.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_alpha_openbsd.cpp
new file mode 100644
index 000000000..dc111e435
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_alpha_openbsd.cpp
@@ -0,0 +1,144 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+/* Prototype specifies unmangled function name and disables unused warning */
+static void
+invoke_copy_to_stack(uint64_t* d, uint32_t paramCount, nsXPTCVariant* s)
+__asm__("invoke_copy_to_stack") __attribute__((used));
+
+static void
+invoke_copy_to_stack(uint64_t* d, uint32_t paramCount, nsXPTCVariant* s)
+{
+    const uint8_t NUM_ARG_REGS = 6-1;        // -1 for "this" pointer
+
+    for(uint32_t i = 0; i < paramCount; i++, d++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            *d = (uint64_t)s->ptr;
+            continue;
+        }
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     : *d = (uint64_t)s->val.i8;     break;
+        case nsXPTType::T_I16    : *d = (uint64_t)s->val.i16;    break;
+        case nsXPTType::T_I32    : *d = (uint64_t)s->val.i32;    break;
+        case nsXPTType::T_I64    : *d = (uint64_t)s->val.i64;    break;
+        case nsXPTType::T_U8     : *d = (uint64_t)s->val.u8;     break;
+        case nsXPTType::T_U16    : *d = (uint64_t)s->val.u16;    break;
+        case nsXPTType::T_U32    : *d = (uint64_t)s->val.u32;    break;
+        case nsXPTType::T_U64    : *d = (uint64_t)s->val.u64;    break;
+        case nsXPTType::T_FLOAT  :
+            if(i < NUM_ARG_REGS)
+            {
+                // convert floats to doubles if they are to be passed
+                // via registers so we can just deal with doubles later
+                union { uint64_t u64; double d; } t;
+                t.d = (double)s->val.f;
+                *d = t.u64;
+            }
+            else
+                // otherwise copy to stack normally
+                *d = (uint64_t)s->val.u32;
+            break;
+        case nsXPTType::T_DOUBLE : *d = (uint64_t)s->val.u64;    break;
+        case nsXPTType::T_BOOL   : *d = (uint64_t)s->val.b;      break;
+        case nsXPTType::T_CHAR   : *d = (uint64_t)s->val.c;      break;
+        case nsXPTType::T_WCHAR  : *d = (uint64_t)s->val.wc;     break;
+        default:
+            // all the others are plain pointer types
+            *d = (uint64_t)s->val.p;
+            break;
+        }
+    }
+}
+
+/*
+ * EXPORT_XPCOM_API(nsresult)
+ * NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+ *                  uint32_t paramCount, nsXPTCVariant* params)
+ */
+__asm__(
+    "#### NS_InvokeByIndex ####\n"
+".text\n\t"
+    ".align 5\n\t"
+    ".globl NS_InvokeByIndex\n\t"
+    ".ent NS_InvokeByIndex\n"
+"NS_InvokeByIndex:\n\t"
+    ".frame $15,32,$26,0\n\t"
+    ".mask 0x4008000,-32\n\t"
+    "ldgp $29,0($27)\n"
+"$NS_InvokeByIndex..ng:\n\t"
+    "subq $30,32,$30\n\t"
+    "stq $26,0($30)\n\t"
+    "stq $15,8($30)\n\t"
+    "bis $30,$30,$15\n\t"
+    ".prologue 1\n\t"
+
+    /*
+     * Allocate enough stack space to hold the greater of 6 or "paramCount"+1
+     * parameters. (+1 for "this" pointer)  Room for at least 6 parameters
+     * is required for storage of those passed via registers.
+     */
+
+    "bis $31,5,$2\n\t"      /* count = MAX(5, "paramCount") */
+    "cmplt $2,$18,$1\n\t"
+    "cmovne $1,$18,$2\n\t"
+    "s8addq $2,16,$1\n\t"   /* room for count+1 params (8 bytes each) */
+    "bic $1,15,$1\n\t"      /* stack space is rounded up to 0 % 16 */
+    "subq $30,$1,$30\n\t"
+
+    "stq $16,0($30)\n\t"    /* save "that" (as "this" pointer) */
+    "stq $17,16($15)\n\t"   /* save "methodIndex" */
+
+    "addq $30,8,$16\n\t"    /* pass stack pointer */
+    "bis $18,$18,$17\n\t"   /* pass "paramCount" */
+    "bis $19,$19,$18\n\t"   /* pass "params" */
+    "bsr $26,$invoke_copy_to_stack..ng\n\t"     /* call invoke_copy_to_stack */
+
+    /*
+     * Copy the first 6 parameters to registers and remove from stack frame.
+     * Both the integer and floating point registers are set for each parameter
+     * except the first which is the "this" pointer.  (integer only)
+     * The floating point registers are all set as doubles since the
+     * invoke_copy_to_stack function should have converted the floats.
+     */
+    "ldq $16,0($30)\n\t"    /* integer registers */
+    "ldq $17,8($30)\n\t"
+    "ldq $18,16($30)\n\t"
+    "ldq $19,24($30)\n\t"
+    "ldq $20,32($30)\n\t"
+    "ldq $21,40($30)\n\t"
+    "ldt $f17,8($30)\n\t"   /* floating point registers */
+    "ldt $f18,16($30)\n\t"
+    "ldt $f19,24($30)\n\t"
+    "ldt $f20,32($30)\n\t"
+    "ldt $f21,40($30)\n\t"
+
+    "addq $30,48,$30\n\t"   /* remove params from stack */
+
+    /*
+     * Call the virtual function with the constructed stack frame.
+     */
+    "bis $16,$16,$1\n\t"    /* load "this" */
+    "ldq $2,16($15)\n\t"    /* load "methodIndex" */
+    "ldq $1,0($1)\n\t"      /* load vtable */
+    "s8addq $2,$31,$2\n\t"  /* vtable index = "methodIndex" * 8 */
+    "addq $1,$2,$1\n\t"
+    "ldq $27,0($1)\n\t"     /* load address of function */
+    "jsr $26,($27),0\n\t"   /* call virtual function */
+    "ldgp $29,0($26)\n\t"
+
+    "bis $15,$15,$30\n\t"
+    "ldq $26,0($30)\n\t"
+    "ldq $15,8($30)\n\t"
+    "addq $30,32,$30\n\t"
+    "ret $31,($26),1\n\t"
+    ".end NS_InvokeByIndex"
+    );
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_arm.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_arm.cpp
new file mode 100644
index 000000000..4cd5eb47d
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_arm.cpp
@@ -0,0 +1,417 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+#include "mozilla/Compiler.h"
+
+#if !defined(__arm__) && !(defined(LINUX) || defined(ANDROID) || defined(XP_IOS))
+#error "This code is for Linux/iOS ARM only. Check that it works on your system, too.\nBeware that this code is highly compiler dependent."
+#endif
+
+#if MOZ_IS_GCC
+#if defined(__ARM_EABI__) && !defined(__ARM_PCS_VFP) && !defined(__ARM_PCS)
+#error "Can't identify floating point calling conventions.\nPlease ensure that your toolchain defines __ARM_PCS or __ARM_PCS_VFP."
+#endif
+#endif
+
+#ifndef __ARM_PCS_VFP
+
+/* This function copies a 64-bits word from dw to the given pointer in
+ * a buffer delimited by start and end, possibly wrapping around the
+ * buffer boundaries, and/or properly aligning the data at 64-bits word
+ * boundaries (for EABI).
+ * start and end are both assumed to be 64-bits aligned.
+ * Returns a pointer to the second 32-bits word copied (to accomodate
+ * the invoke_copy_to_stack loop).
+ */
+static uint32_t *
+copy_double_word(uint32_t *start, uint32_t *current, uint32_t *end, uint64_t *dw)
+{
+#ifdef __ARM_EABI__
+    /* Aligning the pointer for EABI */
+    current = (uint32_t *)(((uint32_t)current + 7) & ~7);
+    /* Wrap when reaching the end of the buffer */
+    if (current == end) current = start;
+#else
+    /* On non-EABI, 64-bits values are not aligned and when we reach the end
+     * of the buffer, we need to write half of the data at the end, and the
+     * other half at the beginning. */
+    if (current == end - 1) {
+        *current = ((uint32_t*)dw)[0];
+        *start = ((uint32_t*)dw)[1];
+        return start;
+    }
+#endif
+
+    *((uint64_t*) current) = *dw;
+    return current + 1;
+}
+
+/* See stack_space comment in NS_InvokeByIndex to see why this needs not to
+ * be static on DEBUG builds. */
+#ifndef DEBUG
+static
+#endif
+void
+invoke_copy_to_stack(uint32_t* stk, uint32_t *end,
+                     uint32_t paramCount, nsXPTCVariant* s)
+{
+    /* The stack buffer is 64-bits aligned. The end argument points to its end.
+     * The caller is assumed to create a stack buffer of at least four 32-bits
+     * words.
+     * We use the last three 32-bit words to store the values for r1, r2 and r3
+     * for the method call, i.e. the first words for arguments passing.
+     */
+    uint32_t *d = end - 3;
+    for(uint32_t i = 0; i < paramCount; i++, d++, s++)
+    {
+        /* Wrap when reaching the end of the stack buffer */
+        if (d == end) d = stk;
+        NS_ASSERTION(d >= stk && d < end,
+            "invoke_copy_to_stack is copying outside its given buffer");
+        if(s->IsPtrData())
+        {
+            *((void**)d) = s->ptr;
+            continue;
+        }
+        // According to the ARM EABI, integral types that are smaller than a word
+        // are to be sign/zero-extended to a full word and treated as 4-byte values.
+
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     : *((int32_t*) d) = s->val.i8;          break;
+        case nsXPTType::T_I16    : *((int32_t*) d) = s->val.i16;         break;
+        case nsXPTType::T_I32    : *((int32_t*) d) = s->val.i32;         break;
+        case nsXPTType::T_I64    :
+            d = copy_double_word(stk, d, end, (uint64_t *)&s->val.i64);
+            break;
+        case nsXPTType::T_U8     : *((uint32_t*)d) = s->val.u8;          break;
+        case nsXPTType::T_U16    : *((uint32_t*)d) = s->val.u16;         break;
+        case nsXPTType::T_U32    : *((uint32_t*)d) = s->val.u32;         break;
+        case nsXPTType::T_U64    :
+            d = copy_double_word(stk, d, end, (uint64_t *)&s->val.u64);
+            break;
+        case nsXPTType::T_FLOAT  : *((float*)   d) = s->val.f;           break;
+        case nsXPTType::T_DOUBLE :
+            d = copy_double_word(stk, d, end, (uint64_t *)&s->val.d);
+            break;
+        case nsXPTType::T_BOOL   : *((int32_t*) d) = s->val.b;           break;
+        case nsXPTType::T_CHAR   : *((int32_t*) d) = s->val.c;           break;
+        case nsXPTType::T_WCHAR  : *((int32_t*) d) = s->val.wc;          break;
+        default:
+            // all the others are plain pointer types
+            *((void**)d) = s->val.p;
+            break;
+        }
+    }
+}
+
+typedef nsresult (*vtable_func)(nsISupports *, uint32_t, uint32_t, uint32_t);
+
+// Avoid AddressSanitizer instrumentation for the next function because it
+// depends on __builtin_alloca behavior and alignment that cannot be relied on
+// once the function is compiled with a version of ASan that has dynamic-alloca
+// instrumentation enabled.
+
+MOZ_ASAN_BLACKLIST
+EXPORT_XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                   uint32_t paramCount, nsXPTCVariant* params)
+{
+
+/* This is to call a given method of class that.
+ * The parameters are in params, the number is in paramCount.
+ * The routine will issue calls to count the number of words
+ * required for argument passing and to copy the arguments to
+ * the stack.
+ * ACPS passes the first 3 params in r1-r3 (with exceptions for 64-bits
+ * arguments), and the remaining goes onto the stack.
+ * We allocate a buffer on the stack for a "worst case" estimate of how much
+ * stack might be needed for EABI, i.e. twice the number of parameters.
+ * The end of this buffer will be used to store r1 to r3, so that the start
+ * of the stack is the remaining parameters.
+ * The magic here is to call the method with "that" and three 32-bits
+ * arguments corresponding to r1-r3, so that the compiler generates the
+ * proper function call. The stack will also contain the remaining arguments.
+ *
+ * !!! IMPORTANT !!!
+ * This routine makes assumptions about the vtable layout of the c++ compiler. It's implemented
+ * for arm-linux GNU g++ >= 2.8.1 (including egcs and gcc-2.95.[1-3])!
+ *
+ */
+ 
+  vtable_func *vtable, func;
+  int base_size = (paramCount > 1) ? paramCount : 2;
+
+/* !!! IMPORTANT !!!
+ * On DEBUG builds, the NS_ASSERTION used in invoke_copy_to_stack needs to use
+ * the stack to pass the 5th argument to NS_DebugBreak. When invoke_copy_to_stack
+ * is inlined, this can result, depending on the compiler and flags, in the
+ * stack pointer not pointing at stack_space when the method is called at the
+ * end of this function. More generally, any function call requiring stack
+ * allocation of arguments is unsafe to be inlined in this function.
+ */
+  uint32_t *stack_space = (uint32_t *) __builtin_alloca(base_size * 8);
+
+  invoke_copy_to_stack(stack_space, &stack_space[base_size * 2],
+                       paramCount, params);
+
+  vtable = *reinterpret_cast<vtable_func **>(that);
+  func = vtable[methodIndex];
+
+  return func(that, stack_space[base_size * 2 - 3],
+                    stack_space[base_size * 2 - 2],
+                    stack_space[base_size * 2 - 1]);
+}    
+
+#else /* __ARM_PCS_VFP */
+
+/* "Procedure Call Standard for the ARM Architecture" document, sections
+ * "5.5 Parameter Passing" and "6.1.2 Procedure Calling" contain all the
+ * needed information.
+ *
+ * http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042d/IHI0042D_aapcs.pdf
+ */
+
+#if defined(__thumb__) && !defined(__thumb2__)
+#error "Thumb1 is not supported"
+#endif
+
+#ifndef __ARMEL__
+#error "Only little endian compatibility was tested"
+#endif
+
+/*
+ * Allocation of integer function arguments initially to registers r1-r3
+ * and then to stack. Handling of 'this' argument which goes to r0 registers
+ * is handled separately and does not belong to these two inline functions.
+ *
+ * The doubleword arguments are allocated to even:odd
+ * register pairs or get aligned at 8-byte boundary on stack. The "holes"
+ * which may appear as a result of this realignment remain unused.
+ *
+ * 'ireg_args'  - pointer to the current position in the buffer,
+ *                corresponding to the register arguments
+ * 'stack_args' - pointer to the current position in the buffer,
+ *                corresponding to the arguments on stack
+ * 'end'        - pointer to the end of the registers argument
+ *                buffer (it is guaranteed to be 8-bytes aligned)
+ */
+
+static inline void copy_word(uint32_t* &ireg_args,
+                             uint32_t* &stack_args,
+                             uint32_t* end,
+                             uint32_t  data)
+{
+  if (ireg_args < end) {
+    *ireg_args = data;
+    ireg_args++;
+  } else {
+    *stack_args = data;
+    stack_args++;
+  }
+}
+
+static inline void copy_dword(uint32_t* &ireg_args,
+                              uint32_t* &stack_args,
+                              uint32_t* end,
+                              uint64_t  data)
+{
+  if (ireg_args + 1 < end) {
+    if ((uint32_t)ireg_args & 4) {
+      ireg_args++;
+    }
+    *(uint64_t *)ireg_args = data;
+    ireg_args += 2;
+  } else {
+    ireg_args = end;
+    if ((uint32_t)stack_args & 4) {
+      stack_args++;
+    }
+    *(uint64_t *)stack_args = data;
+    stack_args += 2;
+  }
+}
+
+/*
+ * Allocation of floating point arguments to VFP registers (s0-s15, d0-d7).
+ *
+ * Unlike integer registers allocation, "back-filling" needs to be
+ * supported. For example, the third floating point argument in the
+ * following function is going to be allocated to s1 register, back-filling
+ * the "hole":
+ *    void f(float s0, double d1, float s1)
+ *
+ * Refer to the "Procedure Call Standard for the ARM Architecture" document
+ * for more details.
+ *
+ * 'vfp_s_args' - pointer to the current position in the buffer with
+ *                the next unallocated single precision register
+ * 'vfp_d_args' - pointer to the current position in the buffer with
+ *                the next unallocated double precision register,
+ *                it has the same value as 'vfp_s_args' when back-filling
+ *                is not used
+ * 'end'        - pointer to the end of the vfp registers argument
+ *                buffer (it is guaranteed to be 8-bytes aligned)
+ *
+ * Mozilla bugtracker has a test program attached which be used for
+ * experimenting with VFP registers allocation code and testing its
+ * correctness:
+ * https://bugzilla.mozilla.org/show_bug.cgi?id=601914#c19
+ */
+
+static inline bool copy_vfp_single(float* &vfp_s_args, double* &vfp_d_args,
+                                   float* end, float data)
+{
+  if (vfp_s_args >= end)
+    return false;
+
+  *vfp_s_args = data;
+  vfp_s_args++;
+  if (vfp_s_args < (float *)vfp_d_args) {
+    // It was the case of back-filling, now the next free single precision
+    // register should overlap with the next free double precision register
+    vfp_s_args = (float *)vfp_d_args;
+  } else if (vfp_s_args > (float *)vfp_d_args) {
+    // also update the pointer to the next free double precision register
+    vfp_d_args++;
+  }
+  return true;
+}
+
+static inline bool copy_vfp_double(float* &vfp_s_args, double* &vfp_d_args,
+                                   float* end, double data)
+{
+  if (vfp_d_args >= (double *)end) {
+    // The back-filling continues only so long as no VFP CPRC has been
+    // allocated to a slot on the stack. Basically no VFP registers can
+    // be allocated after this point.
+    vfp_s_args = end;
+    return false;
+  }
+
+  if (vfp_s_args == (float *)vfp_d_args) {
+    // also update the pointer to the next free single precision register
+    vfp_s_args += 2;
+  }
+  *vfp_d_args = data;
+  vfp_d_args++;
+  return true;
+}
+
+static void
+invoke_copy_to_stack(uint32_t* stk, uint32_t *end,
+                     uint32_t paramCount, nsXPTCVariant* s)
+{
+  uint32_t *ireg_args  = end - 3;
+  float    *vfp_s_args = (float *)end;
+  double   *vfp_d_args = (double *)end;
+  float    *vfp_end    = vfp_s_args + 16;
+
+  for (uint32_t i = 0; i < paramCount; i++, s++) {
+    if (s->IsPtrData()) {
+      copy_word(ireg_args, stk, end, (uint32_t)s->ptr);
+      continue;
+    }
+    // According to the ARM EABI, integral types that are smaller than a word
+    // are to be sign/zero-extended to a full word and treated as 4-byte values
+    switch (s->type)
+    {
+      case nsXPTType::T_FLOAT:
+        if (!copy_vfp_single(vfp_s_args, vfp_d_args, vfp_end, s->val.f)) {
+          copy_word(end, stk, end, reinterpret_cast<uint32_t&>(s->val.f));
+        }
+        break;
+      case nsXPTType::T_DOUBLE:
+        if (!copy_vfp_double(vfp_s_args, vfp_d_args, vfp_end, s->val.d)) {
+          copy_dword(end, stk, end, reinterpret_cast<uint64_t&>(s->val.d));
+        }
+        break;
+      case nsXPTType::T_I8:  copy_word(ireg_args, stk, end, s->val.i8);   break;
+      case nsXPTType::T_I16: copy_word(ireg_args, stk, end, s->val.i16);  break;
+      case nsXPTType::T_I32: copy_word(ireg_args, stk, end, s->val.i32);  break;
+      case nsXPTType::T_I64: copy_dword(ireg_args, stk, end, s->val.i64); break;
+      case nsXPTType::T_U8:  copy_word(ireg_args, stk, end, s->val.u8);   break;
+      case nsXPTType::T_U16: copy_word(ireg_args, stk, end, s->val.u16);  break;
+      case nsXPTType::T_U32: copy_word(ireg_args, stk, end, s->val.u32);  break;
+      case nsXPTType::T_U64: copy_dword(ireg_args, stk, end, s->val.u64); break;
+      case nsXPTType::T_BOOL: copy_word(ireg_args, stk, end, s->val.b);   break;
+      case nsXPTType::T_CHAR: copy_word(ireg_args, stk, end, s->val.c);   break;
+      case nsXPTType::T_WCHAR: copy_word(ireg_args, stk, end, s->val.wc); break;
+      default:
+        // all the others are plain pointer types
+        copy_word(ireg_args, stk, end, reinterpret_cast<uint32_t>(s->val.p));
+        break;
+    }
+  }
+}
+
+typedef uint32_t (*vtable_func)(nsISupports *, uint32_t, uint32_t, uint32_t);
+
+EXPORT_XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                   uint32_t paramCount, nsXPTCVariant* params)
+{
+  vtable_func *vtable = *reinterpret_cast<vtable_func **>(that);
+  vtable_func func = vtable[methodIndex];
+  // 'register uint32_t result asm("r0")' could be used here, but it does not
+  //  seem to be reliable in all cases: http://gcc.gnu.org/PR46164
+  nsresult result;
+  asm (
+    "mov    r3, sp\n"
+    "mov    %[stack_space_size], %[param_count_plus_2], lsl #3\n"
+    "tst    r3, #4\n" /* check stack alignment */
+
+    "add    %[stack_space_size], #(4 * 16)\n" /* space for VFP registers */
+    "mov    r3, %[params]\n"
+
+    "it     ne\n"
+    "addne  %[stack_space_size], %[stack_space_size], #4\n"
+    "sub    r0, sp, %[stack_space_size]\n" /* allocate space on stack */
+
+    "sub    r2, %[param_count_plus_2], #2\n"
+    "mov    sp, r0\n"
+
+    "add    r1, r0, %[param_count_plus_2], lsl #3\n"
+    "blx    %[invoke_copy_to_stack]\n"
+
+    "add    ip, sp, %[param_count_plus_2], lsl #3\n"
+    "mov    r0, %[that]\n"
+    "ldmdb  ip, {r1, r2, r3}\n"
+    "vldm   ip, {d0, d1, d2, d3, d4, d5, d6, d7}\n"
+    "blx    %[func]\n"
+
+    "add    sp, sp, %[stack_space_size]\n" /* cleanup stack */
+    "mov    %[stack_space_size], r0\n" /* it's actually 'result' variable */
+    : [stack_space_size]     "=&r" (result)
+    : [func]                 "r"   (func),
+      [that]                 "r"   (that),
+      [params]               "r"   (params),
+      [param_count_plus_2]   "r"   (paramCount + 2),
+      [invoke_copy_to_stack] "r"   (invoke_copy_to_stack)
+    : "cc", "memory",
+      // Mark all the scratch registers as clobbered because they may be
+      // modified by the functions, called from this inline assembly block
+      "r0", "r1", "r2", "r3", "ip", "lr",
+      "d0",  "d1",  "d2",  "d3",  "d4",  "d5",  "d6",  "d7",
+      // Also unconditionally mark d16-d31 registers as clobbered even though
+      // they actually don't exist in vfpv2 and vfpv3-d16 variants. There is
+      // no way to identify VFP variant using preprocessor at the momemnt
+      // (see http://gcc.gnu.org/PR46128 for more details), but fortunately
+      // current versions of gcc do not seem to complain about these registers
+      // even when this code is compiled with '-mfpu=vfpv3-d16' option.
+      // If gcc becomes more strict in the future and/or provides a way to
+      // identify VFP variant, the following d16-d31 registers list needs
+      // to be wrapped into some #ifdef
+      "d16", "d17", "d18", "d19", "d20", "d21", "d22", "d23",
+      "d24", "d25", "d26", "d27", "d28", "d29", "d30", "d31"
+  );
+  return result;
+}
+
+#endif
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_arm_netbsd.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_arm_netbsd.cpp
new file mode 100644
index 000000000..1b0c214ea
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_arm_netbsd.cpp
@@ -0,0 +1,181 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+// Remember that these 'words' are 32bit DWORDS
+
+static uint32_t
+invoke_count_words(uint32_t paramCount, nsXPTCVariant* s)
+{
+    uint32_t result = 0;
+    for(uint32_t i = 0; i < paramCount; i++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            result++;
+            continue;
+        }
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     :
+        case nsXPTType::T_I16    :
+        case nsXPTType::T_I32    :
+            result++;
+            break;
+        case nsXPTType::T_I64    :
+            result+=2;
+            break;
+        case nsXPTType::T_U8     :
+        case nsXPTType::T_U16    :
+        case nsXPTType::T_U32    :
+            result++;
+            break;
+        case nsXPTType::T_U64    :
+            result+=2;
+            break;
+        case nsXPTType::T_FLOAT  :
+            result++;
+            break;
+        case nsXPTType::T_DOUBLE :
+            result+=2;
+            break;
+        case nsXPTType::T_BOOL   :
+        case nsXPTType::T_CHAR   :
+        case nsXPTType::T_WCHAR  :
+            result++;
+            break;
+        default:
+            // all the others are plain pointer types
+            result++;
+            break;
+        }
+    }
+    return result;
+}
+
+static void
+invoke_copy_to_stack(uint32_t* d, uint32_t paramCount, nsXPTCVariant* s)
+{
+    for(uint32_t i = 0; i < paramCount; i++, d++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            *((void**)d) = s->ptr;
+            continue;
+        }
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     : *((int8_t*)  d) = s->val.i8;          break;
+        case nsXPTType::T_I16    : *((int16_t*) d) = s->val.i16;         break;
+        case nsXPTType::T_I32    : *((int32_t*) d) = s->val.i32;         break;
+        case nsXPTType::T_I64    : *((int64_t*) d) = s->val.i64; d++;    break;
+        case nsXPTType::T_U8     : *((uint8_t*) d) = s->val.u8;          break;
+        case nsXPTType::T_U16    : *((uint16_t*)d) = s->val.u16;         break;
+        case nsXPTType::T_U32    : *((uint32_t*)d) = s->val.u32;         break;
+        case nsXPTType::T_U64    : *((uint64_t*)d) = s->val.u64; d++;    break;
+        case nsXPTType::T_FLOAT  : *((float*)   d) = s->val.f;           break;
+        case nsXPTType::T_DOUBLE : *((double*)  d) = s->val.d;   d++;    break;
+        case nsXPTType::T_BOOL   : *((bool*)  d) = s->val.b;           break;
+        case nsXPTType::T_CHAR   : *((char*)    d) = s->val.c;           break;
+        case nsXPTType::T_WCHAR  : *((wchar_t*) d) = s->val.wc;          break;
+        default:
+            // all the others are plain pointer types
+            *((void**)d) = s->val.p;
+            break;
+        }
+    }
+}
+
+extern "C" 
+struct my_params_struct {
+    nsISupports* that;      
+    uint32_t Index;         
+    uint32_t Count;         
+    nsXPTCVariant* params;  
+    uint32_t fn_count;     
+    uint32_t fn_copy;      
+};
+
+XPTC_PUBLIC_API(nsresult)
+XPTC_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                   uint32_t paramCount, nsXPTCVariant* params)
+{
+    uint32_t result;
+    struct my_params_struct my_params;
+    my_params.that = that;
+    my_params.Index = methodIndex;
+    my_params.Count = paramCount;
+    my_params.params = params;
+    my_params.fn_copy = (uint32_t) &invoke_copy_to_stack;
+    my_params.fn_count = (uint32_t) &invoke_count_words;
+
+/* This is to call a given method of class that.
+ * The parameters are in params, the number is in paramCount.
+ * The routine will issue calls to count the number of words
+ * required for argument passing and to copy the arguments to
+ * the stack.
+ * Since APCS passes the first 3 params in r1-r3, we need to
+ * load the first three words from the stack and correct the stack
+ * pointer (sp) in the appropriate way. This means:
+ *
+ * 1.) more than 3 arguments: load r1-r3, correct sp and remember No.
+ *			      of bytes left on the stack in r4
+ *
+ * 2.) <= 2 args: load r1-r3 (we won't be causing a stack overflow I hope),
+ *		  restore sp as if nothing had happened and set the marker r4 to zero.
+ *
+ * Afterwards sp will be restored using the value in r4 (which is not a temporary register
+ * and will be preserved by the function/method called according to APCS [ARM Procedure
+ * Calling Standard]).
+ *
+ * !!! IMPORTANT !!!
+ * This routine makes assumptions about the vtable layout of the c++ compiler. It's implemented
+ * for arm-linux GNU g++ >= 2.8.1 (including egcs and gcc-2.95.[1-3])!
+ *
+ */
+ 
+  __asm__ __volatile__(
+    "ldr	r1, [%1, #12]	\n\t"	/* prepare to call invoke_count_words	*/
+    "ldr	ip, [%1, #16]	\n\t"	/* r0=paramCount, r1=params		*/
+    "ldr	r0, [%1,  #8]	\n\t"
+    "mov	lr, pc		\n\t"	/* call it...				*/
+    "mov	pc, ip		\n\t"
+    "mov	r4, r0, lsl #2	\n\t"	/* This is the amount of bytes needed.	*/
+    "sub	sp, sp, r4	\n\t"	/* use stack space for the args...	*/
+    "mov	r0, sp		\n\t"	/* prepare a pointer an the stack	*/
+    "ldr	r1, [%1,  #8]	\n\t"	/* =paramCount				*/
+    "ldr	r2, [%1, #12]	\n\t"	/* =params				*/
+    "ldr	ip, [%1, #20]	\n\t"	/* =invoke_copy_to_stack		*/
+    "mov	lr, pc		\n\t"	/* copy args to the stack like the	*/
+    "mov	pc, ip		\n\t"	/* compiler would.			*/
+    "ldr	r0, [%1]	\n\t"	/* =that				*/
+    "ldr	r1, [r0, #0]	\n\t"	/* get that->vtable offset		*/
+    "ldr	r2, [%1, #4]	\n\t"
+    "add	r2, r1, r2, lsl #3\n\t"	/* a vtable_entry(x)=8 + (8 bytes * x)	*/
+    "add	r2, r2, #8	\n\t"	/* with this compilers			*/
+    "ldr	r3, [r2]	\n\t"	/* get virtual offset from vtable	*/
+    "mov	r3, r3, lsl #16	\n\t"
+    "add	r0, r0, r3, asr #16\n\t"
+    "ldr	ip, [r2, #4]	\n\t"	/* get method address from vtable	*/
+    "cmp	r4, #12		\n\t"	/* more than 3 arguments???		*/
+    "ldmgtia	sp!, {r1, r2, r3}\n\t"	/* yes: load arguments for r1-r3	*/
+    "subgt	r4, r4, #12	\n\t"	/*      and correct the stack pointer	*/
+    "ldmleia	sp, {r1, r2, r3}\n\t"	/* no:  load r1-r3 from stack		*/ 
+    "addle	sp, sp, r4	\n\t"	/*      and restore stack pointer	*/
+    "movle	r4, #0		\n\t"	/*	a mark for restoring sp		*/
+    "mov	lr, pc		\n\t"	/* call mathod				*/
+    "mov	pc, ip		\n\t"
+    "add	sp, sp, r4	\n\t"	/* restore stack pointer		*/
+    "mov	%0, r0		\n\t"	/* the result...			*/
+    : "=r" (result)
+    : "r" (&my_params)
+    : "r0", "r1", "r2", "r3", "r4", "ip", "lr"
+    );
+    
+  return result;
+}    
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_arm_openbsd.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_arm_openbsd.cpp
new file mode 100644
index 000000000..4ec7dd20f
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_arm_openbsd.cpp
@@ -0,0 +1,183 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+// Remember that these 'words' are 32bit DWORDS
+
+static uint32_t
+invoke_count_words(uint32_t paramCount, nsXPTCVariant* s)
+{
+    uint32_t result = 0;
+    for(uint32_t i = 0; i < paramCount; i++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            result++;
+            continue;
+        }
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     :
+        case nsXPTType::T_I16    :
+        case nsXPTType::T_I32    :
+            result++;
+            break;
+        case nsXPTType::T_I64    :
+            result+=2;
+            break;
+        case nsXPTType::T_U8     :
+        case nsXPTType::T_U16    :
+        case nsXPTType::T_U32    :
+            result++;
+            break;
+        case nsXPTType::T_U64    :
+            result+=2;
+            break;
+        case nsXPTType::T_FLOAT  :
+            result++;
+            break;
+        case nsXPTType::T_DOUBLE :
+            result+=2;
+            break;
+        case nsXPTType::T_BOOL   :
+        case nsXPTType::T_CHAR   :
+        case nsXPTType::T_WCHAR  :
+            result++;
+            break;
+        default:
+            // all the others are plain pointer types
+            result++;
+            break;
+        }
+    }
+    return result;
+}
+
+static void
+invoke_copy_to_stack(uint32_t* d, uint32_t paramCount, nsXPTCVariant* s)
+{
+    for(uint32_t i = 0; i < paramCount; i++, d++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            *((void**)d) = s->ptr;
+            continue;
+        }
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     : *((int8_t*)  d) = s->val.i8;          break;
+        case nsXPTType::T_I16    : *((int16_t*) d) = s->val.i16;         break;
+        case nsXPTType::T_I32    : *((int32_t*) d) = s->val.i32;         break;
+        case nsXPTType::T_I64    : *((int64_t*) d) = s->val.i64; d++;    break;
+        case nsXPTType::T_U8     : *((uint8_t*) d) = s->val.u8;          break;
+        case nsXPTType::T_U16    : *((uint16_t*)d) = s->val.u16;         break;
+        case nsXPTType::T_U32    : *((uint32_t*)d) = s->val.u32;         break;
+        case nsXPTType::T_U64    : *((uint64_t*)d) = s->val.u64; d++;    break;
+        case nsXPTType::T_FLOAT  : *((float*)   d) = s->val.f;           break;
+        case nsXPTType::T_DOUBLE : *((double*)  d) = s->val.d;   d++;    break;
+        case nsXPTType::T_BOOL   : *((bool*)  d) = s->val.b;           break;
+        case nsXPTType::T_CHAR   : *((char*)    d) = s->val.c;           break;
+        case nsXPTType::T_WCHAR  : *((wchar_t*) d) = s->val.wc;          break;
+        default:
+            // all the others are plain pointer types
+            *((void**)d) = s->val.p;
+            break;
+        }
+    }
+}
+
+extern "C" {
+    struct my_params_struct {
+        nsISupports* that;      
+        uint32_t Index;         
+        uint32_t Count;         
+        nsXPTCVariant* params;  
+        uint32_t fn_count;     
+        uint32_t fn_copy;      
+    };
+}
+
+EXPORT_XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                   uint32_t paramCount, nsXPTCVariant* params)
+{
+    uint32_t result;
+    struct my_params_struct my_params;
+    my_params.that = that;
+    my_params.Index = methodIndex;
+    my_params.Count = paramCount;
+    my_params.params = params;
+    my_params.fn_copy = (uint32_t) &invoke_copy_to_stack;
+    my_params.fn_count = (uint32_t) &invoke_count_words;
+
+/* This is to call a given method of class that.
+ * The parameters are in params, the number is in paramCount.
+ * The routine will issue calls to count the number of words
+ * required for argument passing and to copy the arguments to
+ * the stack.
+ * Since APCS passes the first 3 params in r1-r3, we need to
+ * load the first three words from the stack and correct the stack
+ * pointer (sp) in the appropriate way. This means:
+ *
+ * 1.) more than 3 arguments: load r1-r3, correct sp and remember No.
+ *			      of bytes left on the stack in r4
+ *
+ * 2.) <= 2 args: load r1-r3 (we won't be causing a stack overflow I hope),
+ *		  restore sp as if nothing had happened and set the marker r4 to zero.
+ *
+ * Afterwards sp will be restored using the value in r4 (which is not a temporary register
+ * and will be preserved by the function/method called according to APCS [ARM Procedure
+ * Calling Standard]).
+ *
+ * !!! IMPORTANT !!!
+ * This routine makes assumptions about the vtable layout of the c++ compiler. It's implemented
+ * for arm-linux GNU g++ >= 2.8.1 (including egcs and gcc-2.95.[1-3])!
+ *
+ */
+
+#ifdef __GNUC__
+  __asm__ __volatile__(
+    "ldr	r1, [%1, #12]	\n\t"	/* prepare to call invoke_count_words	*/
+    "ldr	ip, [%1, #16]	\n\t"	/* r0=paramCount, r1=params		*/
+    "ldr	r0, [%1,  #8]	\n\t"
+    "mov	lr, pc		\n\t"	/* call it...				*/
+    "mov	pc, ip		\n\t"
+    "mov	r4, r0, lsl #2	\n\t"	/* This is the amount of bytes needed.	*/
+    "sub	sp, sp, r4	\n\t"	/* use stack space for the args...	*/
+    "mov	r0, sp		\n\t"	/* prepare a pointer an the stack	*/
+    "ldr	r1, [%1,  #8]	\n\t"	/* =paramCount				*/
+    "ldr	r2, [%1, #12]	\n\t"	/* =params				*/
+    "ldr	ip, [%1, #20]	\n\t"	/* =invoke_copy_to_stack		*/
+    "mov	lr, pc		\n\t"	/* copy args to the stack like the	*/
+    "mov	pc, ip		\n\t"	/* compiler would.			*/
+    "ldr	r0, [%1]	\n\t"	/* =that				*/
+    "ldr	r1, [r0, #0]	\n\t"	/* get that->vtable offset		*/
+    "ldr	r2, [%1, #4]	\n\t"
+    "mov	r2, r2, lsl #2	\n\t"	/* a vtable_entry(x)=8 + (4 bytes * x)	*/
+    "ldr        ip, [r1, r2]    \n\t"	/* get method adress from vtable        */
+    "cmp	r4, #12		\n\t"	/* more than 3 arguments???		*/
+    "ldmgtia	sp!, {r1, r2, r3}\n\t"	/* yes: load arguments for r1-r3	*/
+    "subgt	r4, r4, #12	\n\t"	/*      and correct the stack pointer	*/
+    "ldmleia	sp, {r1, r2, r3}\n\t"	/* no:  load r1-r3 from stack		*/ 
+    "addle	sp, sp, r4	\n\t"	/*      and restore stack pointer	*/
+    "movle	r4, #0		\n\t"	/*	a mark for restoring sp		*/
+    "ldr	r0, [%1, #0]	\n\t"	/* get (self)				*/
+    "mov	lr, pc		\n\t"	/* call mathod				*/
+    "mov	pc, ip		\n\t"
+    "add	sp, sp, r4	\n\t"	/* restore stack pointer		*/
+    "mov	%0, r0		\n\t"	/* the result...			*/
+    : "=r" (result)
+    : "r" (&my_params), "m" (my_params)
+    : "r0", "r1", "r2", "r3", "r4", "ip", "lr", "sp"
+    );
+#else
+#error "Unsupported compiler. Use g++ >= 2.8 for OpenBSD/arm."
+#endif /* G++ >= 2.8 */
+
+  return result;
+}    
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_aarch64.s b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_aarch64.s
new file mode 100644
index 000000000..efe691a68
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_aarch64.s
@@ -0,0 +1,67 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+        .section ".text"
+            .globl _NS_InvokeByIndex
+            .type  _NS_InvokeByIndex,@function
+
+/*
+ * _NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+ *                   uint32_t paramCount, nsXPTCVariant* params)
+ */
+
+_NS_InvokeByIndex:
+            # set up frame
+            stp         x29, x30, [sp,#-32]!
+            mov         x29, sp
+            stp         x19, x20, [sp,#16]
+
+            # save methodIndex across function calls
+            mov         w20, w1
+
+            # end of stack area passed to invoke_copy_to_stack
+            mov         x1, sp
+
+            # assume 8 bytes of stack for each argument with 16-byte alignment
+            add         w19, w2, #1
+            and         w19, w19, #0xfffffffe
+            sub         sp, sp, w19, uxth #3
+
+            # temporary place to store args passed in r0-r7,v0-v7
+            sub         sp, sp, #128
+
+            # save 'that' on stack
+            str         x0, [sp]
+
+            # start of stack area passed to invoke_copy_to_stack
+            mov         x0, sp
+            bl          invoke_copy_to_stack
+
+            # load arguments passed in r0-r7
+            ldp         x6, x7, [sp, #48]
+            ldp         x4, x5, [sp, #32]
+            ldp         x2, x3, [sp, #16]
+            ldp         x0, x1, [sp],#64
+
+            # load arguments passed in v0-v7
+            ldp         d6, d7, [sp, #48]
+            ldp         d4, d5, [sp, #32]
+            ldp         d2, d3, [sp, #16]
+            ldp         d0, d1, [sp],#64
+
+            # call the method
+            ldr         x16, [x0]
+            add         x16, x16, w20, uxth #3
+            ldr         x16, [x16]
+            blr         x16
+
+            add         sp, sp, w19, uxth #3
+            ldp         x19, x20, [sp,#16]
+            ldp         x29, x30, [sp],#32
+            ret
+
+            .size _NS_InvokeByIndex, . - _NS_InvokeByIndex
+
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ipf32.s b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ipf32.s
new file mode 100644
index 000000000..794c4f5c1
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ipf32.s
@@ -0,0 +1,145 @@
+
+// Select C numeric constant
+        .radix  C
+// for 64 bit mode, use .psr abi64
+        .psr    abi32
+// big endian
+        .psr    msb
+// Section has executable code
+        .section .text, "ax","progbits"
+// procedure named 'NS_InvokeByIndex'
+        .proc   NS_InvokeByIndex
+// manual bundling
+        .explicit
+
+// extern "C" uint32_t
+// invoke_copy_to_stack(uint64_t* d,
+//   const uint32_t paramCount, nsXPTCVariant* s)
+        .global invoke_copy_to_stack
+//      .exclass  invoke_copy_to_stack, @fullyvisible
+        .type   invoke_copy_to_stack,@function
+
+//      .exclass  NS_InvokeByIndex, @fullyvisible
+        .type   NS_InvokeByIndex,@function
+
+// NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+//   uint32_t paramCount, nsXPTCVariant* params);
+NS_InvokeByIndex::
+        .prologue
+        .save ar.pfs, r37
+// allocate 4 input args, 6 local args, and 8 output args
+        alloc           r37 = ar.pfs, 4, 6, 8, 0   // M
+        nop.i           0                       ;; // I
+
+// unwind table already knows gp, no need to specify anything
+        add             r39 = 0, gp                // A
+        .save rp, r36
+        mov             r36 = rp                   // I
+        .vframe r38
+        add             r38 = 0, sp             ;; // A
+
+// We first calculate the amount of extra memory stack space required
+// for the arguments, and register storage.
+// We then call invoke_copy_to_stack() to write the argument contents
+// to the specified memory regions.
+// We then copy the integer arguments to integer registers, and floating
+// arguments to float registers.
+// Lastly we load the virtual table jump pointer, and call the target
+// subroutine.
+
+// in0 : that
+// in1 : methodIndex
+// in2 : paramCount
+// in3 : params
+
+// stack frame size is 16 + (8 * even(paramCount)) + 64 + 64
+// 16 byte frame header
+// 8 * even(paramCount) memory argument area
+// 64 bytes integer register area
+// 64 bytes float register area
+// This scheme makes sure stack fram size is a multiple of 16
+
+        .body
+        add             r10 = 8, r0          // A
+// r41 points to float register area
+        add             r41 = -64, sp        // A
+// r40 points to int register area
+        add             r40 = -128, sp    ;; // A
+
+        add             out1 = 0, r40        // A
+        add             out2 = 0, r41        // A
+        tbit.z          p14,p15 = in2,0   ;; // I
+
+// compute 8 * even(paramCount)
+(p14)   shladd          r11 = in2, 3, r0  ;; // A
+(p15)   shladd          r11 = in2, 3, r10 ;; // A
+        sub             out0 = r40, r11   ;; // A
+
+// advance the stack frame
+        add             sp = -16, out0       // A
+        add             out3 = 0, in2        // A
+        add             out4 = 0, in3        // A
+
+// branch to invoke_copy_to_stack
+        br.call.sptk.few rp = invoke_copy_to_stack ;; // B
+
+// restore gp
+        add             gp = 0, r39          // A
+        add             out0 = 0, in0        // A
+
+// load the integer and float registers
+        ld8             out1 = [r40], 8      // M
+        ldfd            f8 = [r41], 8       ;; // M
+
+        ld8             out2 = [r40], 8      // M
+        ldfd            f9 = [r41], 8       ;; // M
+
+        ld8             out3 = [r40], 8      // M
+        ldfd            f10 = [r41], 8      ;; // M
+
+        ld8             out4 = [r40], 8      // M
+        ldfd            f11 = [r41], 8      ;; // M
+
+        ld8             out5 = [r40], 8      // M
+        ldfd            f12 = [r41], 8      ;; // M
+// 16 * methodIndex
+        shladd          r11 = in1, 4, r0     // A
+
+        ld8             out6 = [r40], 8      // M
+        ldfd            f13 = [r41], 8      ;; // M
+
+        ld8             out7 = [r40], 8      // M
+        ldfd            f14 = [r41], 8       // M
+        addp4           r8 = 0, in0       ;; // A
+
+// look up virtual base table and dispatch to target subroutine
+// This section assumes 32 bit pointer mode, and virtual base table
+// layout from the ABI http://www.codesourcery.com/cxx-abi/abi.html
+
+// load base table
+        ld4             r8 = [r8]         ;; // M
+        addp4           r8 = r11, r8      ;; // A
+
+ // first entry is jump pointer, second entry is gp
+        addp4           r9 = 8, r8       ;; // A
+// load jump pointer
+        ld8             r8 = [r8]
+
+// load gp
+        ld8             gp = [r9]        ;; // M
+        mov             b6 = r8          ;; // I
+
+// branch to target virtual function
+        br.call.sptk.few rp = b6          ;; // B
+
+// epilog
+        mov             ar.pfs = r37         // I
+        mov             rp = r36          ;; // I
+
+        add             sp = 0, r38          // A
+        add             gp = 0, r39          // A
+        br.ret.sptk.few rp                ;; // B
+
+        .endp
+
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ipf64.s b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ipf64.s
new file mode 100644
index 000000000..140c44117
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ipf64.s
@@ -0,0 +1,146 @@
+
+// Select C numeric constant
+        .radix  C
+// for 64 bit mode, use .psr abi64
+        .psr    abi64
+// little endian
+        .psr    lsb
+// Section has executable code
+        .section .text, "ax","progbits"
+// procedure named 'NS_InvokeByIndex'
+        .proc   NS_InvokeByIndex
+// manual bundling
+        .explicit
+
+// extern "C" uint32_t
+// invoke_copy_to_stack(uint64_t* d,
+//   const uint32_t paramCount, nsXPTCVariant* s)
+        .global invoke_copy_to_stack
+//      .exclass  invoke_copy_to_stack, @fullyvisible
+        .type   invoke_copy_to_stack,@function
+
+//      .exclass  NS_InvokeByIndex, @fullyvisible
+        .type   NS_InvokeByIndex,@function
+
+// XPTC_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+//   uint32_t paramCount, nsXPTCVariant* params);
+NS_InvokeByIndex::
+        .prologue
+        .save ar.pfs, r37
+// allocate 4 input args, 6 local args, and 8 output args
+        alloc           r37 = ar.pfs, 4, 6, 8, 0   // M
+        nop.i           0                       ;; // I
+
+// unwind table already knows gp, no need to specify anything
+        add             r39 = 0, gp                // A
+        .save rp, r36
+        mov             r36 = rp                   // I
+        .vframe r38
+        add             r38 = 0, sp             ;; // A
+
+// We first calculate the amount of extra memory stack space required
+// for the arguments, and register storage.
+// We then call invoke_copy_to_stack() to write the argument contents
+// to the specified memory regions.
+// We then copy the integer arguments to integer registers, and floating
+// arguments to float registers.
+// Lastly we load the virtual table jump pointer, and call the target
+// subroutine.
+
+// in0 : that
+// in1 : methodIndex
+// in2 : paramCount
+// in3 : params
+
+// stack frame size is 16 + (8 * even(paramCount)) + 64 + 64
+// 16 byte frame header
+// 8 * even(paramCount) memory argument area
+// 64 bytes integer register area
+// 64 bytes float register area
+// This scheme makes sure stack fram size is a multiple of 16
+
+        .body
+        add             r10 = 8, r0          // A
+// r41 points to float register area
+        add             r41 = -64, sp        // A
+// r40 points to int register area
+        add             r40 = -128, sp    ;; // A
+
+        add             out1 = 0, r40        // A
+        add             out2 = 0, r41        // A
+        tbit.z          p14,p15 = in2,0   ;; // I
+
+// compute 8 * even(paramCount)
+(p14)   shladd          r11 = in2, 3, r0  ;; // A
+(p15)   shladd          r11 = in2, 3, r10 ;; // A
+        sub             out0 = r40, r11   ;; // A
+
+// advance the stack frame
+        add             sp = -16, out0       // A
+        add             out3 = 0, in2        // A
+        add             out4 = 0, in3        // A
+
+// branch to invoke_copy_to_stack
+        br.call.sptk.few rp = invoke_copy_to_stack ;; // B
+
+// restore gp
+        add             gp = 0, r39          // A
+        add             out0 = 0, in0        // A
+
+// load the integer and float registers
+        ld8             out1 = [r40], 8      // M
+        ldfd            f8 = [r41], 8       ;; // M
+
+        ld8             out2 = [r40], 8      // M
+        ldfd            f9 = [r41], 8       ;; // M
+
+        ld8             out3 = [r40], 8      // M
+        ldfd            f10 = [r41], 8      ;; // M
+
+        ld8             out4 = [r40], 8      // M
+        ldfd            f11 = [r41], 8      ;; // M
+
+        ld8             out5 = [r40], 8      // M
+        ldfd            f12 = [r41], 8      ;; // M
+// 16 * methodIndex
+        shladd          r11 = in1, 4, r0     // A
+
+        ld8             out6 = [r40], 8      // M
+        ldfd            f13 = [r41], 8      ;; // M
+
+        ld8             out7 = [r40], 8      // M
+        ldfd            f14 = [r41], 8       // M
+        add             r8 = 0, in0       ;; // A
+
+// look up virtual base table and dispatch to target subroutine
+// This section assumes 64 bit pointer mode, and virtual base table
+// layout from the ABI http://www.codesourcery.com/cxx-abi/abi.html
+
+// load base table
+        ld8             r8 = [r8]         ;; // M
+        add             r8 = r11, r8      ;; // A
+
+ // first entry is jump pointer, second entry is gp
+        add             r9 = 8, r8       ;; // A
+// load jump pointer
+        ld8             r8 = [r8]
+
+// load gp
+        ld8             gp = [r9]        ;; // M
+        mov             b6 = r8          ;; // I
+
+// branch to target virtual function
+        br.call.sptk.few rp = b6          ;; // B
+
+// epilog
+        mov             ar.pfs = r37         // I
+        mov             rp = r36          ;; // I
+
+        add             sp = 0, r38          // A
+        add             gp = 0, r39          // A
+        br.ret.sptk.few rp                ;; // B
+
+        .endp
+
+/* Magic indicating no need for an executable stack */
+.section .note.GNU-stack, "", @progbits ; .previous
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_mips.S b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_mips.S
new file mode 100644
index 000000000..32ff3b356
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_mips.S
@@ -0,0 +1,134 @@
+/* -*- Mode: asm; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * Version: MPL 1.1
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* This code is for MIPS using the O32 ABI. */
+
+#ifdef ANDROID
+#include <asm/regdef.h>
+#include <asm/asm.h>
+#include <machine/asm.h>
+#else
+#include <sys/regdef.h>
+#include <sys/asm.h>
+#endif
+
+# NARGSAVE is the argument space in the callers frame, including extra
+# 'shadowed' space for the argument registers. The minimum of 4
+# argument slots is sometimes predefined in the header files.
+#ifndef NARGSAVE
+#define NARGSAVE 4
+#endif
+
+#define LOCALSZ 3	/* gp, fp, ra */
+#define FRAMESZ ((((NARGSAVE+LOCALSZ)*SZREG)+ALSZ)&ALMASK)
+
+#define RAOFF (FRAMESZ - (1*SZREG))
+#define FPOFF (FRAMESZ - (2*SZREG))
+#define GPOFF (FRAMESZ - (3*SZREG))
+
+#define A0OFF (FRAMESZ + (0*SZREG))
+#define A1OFF (FRAMESZ + (1*SZREG))
+#define A2OFF (FRAMESZ + (2*SZREG))
+#define A3OFF (FRAMESZ + (3*SZREG))
+
+	.text
+
+#	
+# _NS_InvokeByIndex(that, methodIndex, paramCount, params)
+#                      a0       a1          a2         a3
+
+	.globl	_NS_InvokeByIndex
+	.align	2
+	.type	_NS_InvokeByIndex,@function
+	.ent	_NS_InvokeByIndex,0
+	.frame	fp, FRAMESZ, ra
+_NS_InvokeByIndex:
+	SETUP_GP
+	subu	sp, FRAMESZ
+
+	# specify the save register mask for gp, fp, ra, a3 - a0
+	.mask 0xD00000F0, RAOFF-FRAMESZ
+
+	sw	ra, RAOFF(sp)
+	sw	fp, FPOFF(sp)
+
+	# we can't use .cprestore in a variable stack frame
+	sw	gp, GPOFF(sp)
+
+	sw	a0, A0OFF(sp)
+	sw	a1, A1OFF(sp)
+	sw	a2, A2OFF(sp)
+	sw	a3, A3OFF(sp)
+
+	# save bottom of fixed frame
+	move	fp, sp
+
+	# extern "C" uint32
+	# invoke_count_words(uint32_t paramCount, nsXPTCVariant* s);
+	la	t9, invoke_count_words
+	move	a0, a2
+	move	a1, a3
+	jalr	t9
+	lw  	gp, GPOFF(fp)
+
+	# allocate variable stack, with a size of:
+	# wordsize (of 4 bytes) * result (already aligned to dword)
+	# but a minimum of 16 byte
+	sll	v0, 2
+	slt	t0, v0, 16
+	beqz	t0, 1f
+	li	v0, 16
+1:	subu	sp, v0
+
+	# let a0 point to the bottom of the variable stack, allocate
+	# another fixed stack for:
+	# extern "C" void
+	# invoke_copy_to_stack(uint32_t* d, uint32_t paramCount,
+	#		       nsXPTCVariant* s);
+	la	t9, invoke_copy_to_stack
+	move	a0, sp
+	lw	a1, A2OFF(fp)
+	lw	a2, A3OFF(fp)
+	subu	sp, 16
+	jalr	t9
+	lw  	gp, GPOFF(fp)
+
+	# back to the variable stack frame
+	addu	sp, 16
+
+	# calculate the function we need to jump to, which must then be
+	# stored in t9
+	lw	a0, A0OFF(fp)	# a0 = set "that" to be "this"
+	lw	t0, A1OFF(fp)	# a1 = methodIndex
+	lw	t9, 0(a0)
+	# t0 = methodIndex << PTRLOG
+	sll	t0, t0, PTRLOG
+	addu	t9, t0
+	lw	t9, (t9)
+
+	# Set a1-a3 to what invoke_copy_to_stack told us. a0 is already
+	# the "this" pointer. We don't have to care about floating
+	# point arguments, the non-FP "this" pointer as first argument
+	# means they'll never be used.
+	lw	a1, 1*SZREG(sp)
+	lw	a2, 2*SZREG(sp)
+	lw	a3, 3*SZREG(sp)
+
+	jalr	t9
+	# Micro-optimization: There's no gp usage below this point, so
+	# we don't reload.
+	# lw	gp, GPOFF(fp)
+
+	# leave variable stack frame
+	move	sp, fp
+
+	lw	ra, RAOFF(sp)
+	lw	fp, FPOFF(sp)
+
+	addiu	sp, FRAMESZ
+	j	ra
+END(_NS_InvokeByIndex)
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_mips64.S b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_mips64.S
new file mode 100644
index 000000000..eef34de7f
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_mips64.S
@@ -0,0 +1,122 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include <sys/regdef.h>
+#include <sys/asm.h>
+
+.text
+.globl  invoke_count_words
+.globl  invoke_copy_to_stack
+
+LOCALSZ=7        # a0, a1, a2, a3, s0, ra, gp
+FRAMESZ=(((NARGSAVE+LOCALSZ)*SZREG)+ALSZ)&ALMASK
+
+RAOFF=FRAMESZ-(1*SZREG)
+A0OFF=FRAMESZ-(2*SZREG)
+A1OFF=FRAMESZ-(3*SZREG)
+A2OFF=FRAMESZ-(4*SZREG)
+A3OFF=FRAMESZ-(5*SZREG)
+S0OFF=FRAMESZ-(6*SZREG)
+GPOFF=FRAMESZ-(7*SZREG)
+
+#
+# _NS_InvokeByIndex(that, methodIndex, paramCount, params)
+#                      a0       a1          a2         a3
+
+NESTED(_NS_InvokeByIndex, FRAMESZ, ra)
+    PTR_SUBU sp, FRAMESZ
+    SETUP_GP64(GPOFF, _NS_InvokeByIndex)
+
+    REG_S    ra, RAOFF(sp)
+    REG_S    a0, A0OFF(sp)
+    REG_S    a1, A1OFF(sp)
+    REG_S    a2, A2OFF(sp)
+    REG_S    a3, A3OFF(sp)
+    REG_S    s0, S0OFF(sp)
+
+    # invoke_count_words(paramCount, params)
+    move     a0, a2
+    move     a1, a3
+    jal      invoke_count_words
+
+    # invoke_copy_to_stack(uint32_t* d, uint32_t paramCount,
+    #                      nsXPTCVariant* s, uint32_t *reg)
+
+    REG_L    a1, A2OFF(sp) # a1 - paramCount
+    REG_L    a2, A3OFF(sp) # a2 - params
+
+    # save sp before we copy the params to the stack
+    move     t0, sp
+
+    # assume full size of 16 bytes per param to be safe
+    sll      v0, 4         # 16 bytes * num params
+    PTR_SUBU sp, sp, v0    # make room
+    move     a0, sp        # a0 - param stack address
+
+    # create temporary stack space to write int and fp regs
+    PTR_SUBU sp, 64        # 64 = 8 regs of 8 bytes
+    move     a3, sp
+
+    # save the old sp and save the arg stack
+    PTR_SUBU sp, sp, 16
+    REG_S    t0, 0(sp)
+    REG_S    a0, 8(sp)
+
+    # copy the param into the stack areas
+    jal      invoke_copy_to_stack
+
+    REG_L    t3, 8(sp)     # get previous a0
+    REG_L    sp, 0(sp)     # get orig sp back
+
+    REG_L    a0, A0OFF(sp) # a0 - that
+    REG_L    a1, A1OFF(sp) # a1 - methodIndex
+
+    # t1 = methodIndex * pow(2, PTRLOG)
+    # (use shift instead of mult)
+    sll      t1, a1, PTRLOG
+
+    # calculate the function we need to jump to,
+    # which must then be saved in t9
+    PTR_L    t9, 0(a0)
+    PTR_ADDU t9, t9, t1
+    PTR_L    t9, (t9)
+
+    # get register save area from invoke_copy_to_stack
+    PTR_SUBU t1, t3, 64
+
+    # a1..a7 and f13..f19 should now be set to what
+    # invoke_copy_to_stack told us. skip a0 and f12
+    # because that's the "this" pointer
+
+    REG_L    a1,  0(t1)
+    REG_L    a2,  8(t1)
+    REG_L    a3, 16(t1)
+    REG_L    a4, 24(t1)
+    REG_L    a5, 32(t1)
+    REG_L    a6, 40(t1)
+    REG_L    a7, 48(t1)
+
+    l.d      $f13,  0(t1)
+    l.d      $f14,  8(t1)
+    l.d      $f15, 16(t1)
+    l.d      $f16, 24(t1)
+    l.d      $f17, 32(t1)
+    l.d      $f18, 40(t1)
+    l.d      $f19, 48(t1)
+
+    # save away our stack pointer and create
+    # the stack pointer for the function
+    move     s0, sp
+    move     sp, t3
+
+    jalr     t9
+
+    move     sp, s0
+
+    RESTORE_GP64
+    REG_L    ra, RAOFF(sp)
+    REG_L    s0, S0OFF(sp)
+    PTR_ADDU sp, FRAMESZ
+    j    ra
+.end _NS_InvokeByIndex
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_pa32.s b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_pa32.s
new file mode 100644
index 000000000..6fa9a86ba
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_pa32.s
@@ -0,0 +1,131 @@
+  .LEVEL  1.1
+framesz .EQU 128
+
+; XPTC_InvokeByIndex(nsISuppots* that, uint32_t methodIndex,
+;   uint32_t paramCount, nsXPTCVariant* params);
+
+; g++ need to compile everything with -fvtable-thunks !
+
+  .SPACE  $TEXT$,SORT=8
+  .SUBSPA $CODE$,QUAD=0,ALIGN=4,ACCESS=0x2c,CODE_ONLY,SORT=24
+XPTC_InvokeByIndex
+  .PROC
+  .CALLINFO CALLER,FRAME=72,ENTRY_GR=%r3,SAVE_RP,SAVE_SP,ARGS_SAVED,ALLOCA_FRAME
+
+ ; frame marker takes 48 bytes,
+ ; register spill area takes 8 bytes,
+ ; local stack area takes 72 bytes result in 128 bytes total
+
+  .ENTRY
+        STW          %rp,-20(%sp)
+        STW,MA       %r3,128(%sp)
+
+        LDO     -framesz(%r30),%r28
+        STW     %r28,-4(%r30)       ; save previous sp
+        STW     %r19,-32(%r30)
+
+        STW     %r26,-36-framesz(%r30)  ; save argument registers in
+        STW     %r25,-40-framesz(%r30)  ; in PREVIOUS frame
+        STW     %r24,-44-framesz(%r30)  ;
+        STW     %r23,-48-framesz(%r30)  ;
+
+        B,L     .+8,%r2
+        ADDIL   L'invoke_count_bytes-$PIC_pcrel$1+4,%r2,%r1
+        LDO     R'invoke_count_bytes-$PIC_pcrel$2+8(%r1),%r1
+$PIC_pcrel$1
+        LDSID   (%r1),%r31
+$PIC_pcrel$2
+        MTSP    %r31,%sr0
+        .CALL   ARGW0=GR,ARGW1=GR,ARGW2=GR ;in=24,25,26;out=28
+        BE,L    0(%sr0,%r1),%r31
+        COPY    %r31,%r2
+
+        CMPIB,>=        0,%r28, .+76
+        COPY    %r30,%r3            ; copy stack ptr to saved stack ptr
+        ADD     %r30,%r28,%r30      ; extend stack frame
+        LDW     -4(%r3),%r28        ; move frame
+        STW     %r28,-4(%r30)
+        LDW     -8(%r3),%r28
+        STW     %r28,-8(%r30)
+        LDW     -12(%r3),%r28
+        STW     %r28,-12(%r30)
+        LDW     -16(%r3),%r28
+        STW     %r28,-16(%r30)
+        LDW     -20(%r3),%r28
+        STW     %r28,-20(%r30)
+        LDW     -24(%r3),%r28
+        STW     %r28,-24(%r30)
+        LDW     -28(%r3),%r28
+        STW     %r28,-28(%r30)
+        LDW     -32(%r3),%r28
+        STW     %r28,-32(%r30)
+
+        LDO     -40(%r30),%r26         ; load copy address
+        LDW     -44-framesz(%r3),%r25  ; load rest of 2 arguments
+        LDW     -48-framesz(%r3),%r24  ;
+
+        LDW     -32(%r30),%r19 ; shared lib call destroys r19; reload
+        B,L     .+8,%r2
+        ADDIL   L'invoke_copy_to_stack-$PIC_pcrel$3+4,%r2,%r1
+        LDO     R'invoke_copy_to_stack-$PIC_pcrel$4+8(%r1),%r1
+$PIC_pcrel$3
+        LDSID   (%r1),%r31
+$PIC_pcrel$4
+        MTSP    %r31,%sr0
+        .CALL   ARGW0=GR,ARGW1=GR,ARGW2=GR ;in=24,25,26
+        BE,L    0(%sr0,%r1),%r31
+        COPY    %r31,%r2
+
+        LDO     -48(%r30),%r20
+        EXTRW,U,= %r28,31,1,%r22
+        FLDD    0(%r20),%fr7  ; load double arg 1
+        EXTRW,U,= %r28,30,1,%r22
+        FLDW    8(%r20),%fr5L ; load float arg 1
+        EXTRW,U,= %r28,29,1,%r22
+        FLDW    4(%r20),%fr6L ; load float arg 2
+        EXTRW,U,= %r28,28,1,%r22
+        FLDW    0(%r20),%fr7L ; load float arg 3
+
+        LDW     -36-framesz(%r3),%r26  ; load ptr to 'that'
+        LDW     -40(%r30),%r25  ; load the rest of dispatch argument registers
+        LDW     -44(%r30),%r24
+        LDW     -48(%r30),%r23
+
+        LDW     -36-framesz(%r3),%r20  ; load vtable addr
+        LDW     -40-framesz(%r3),%r28  ; load index
+        LDW     0(%r20),%r20    ; follow vtable
+        LDO     16(%r20),%r20   ; offset vtable by 16 bytes (g++: 8, aCC: 16)
+        SH2ADDL %r28,%r20,%r28  ; add 4*index to vtable entry
+        LDW     0(%r28),%r22    ; load vtable entry
+
+        B,L     .+8,%r2
+        ADDIL   L'$$dyncall_external-$PIC_pcrel$5+4,%r2,%r1
+        LDO     R'$$dyncall_external-$PIC_pcrel$6+8(%r1),%r1
+$PIC_pcrel$5
+        LDSID   (%r1),%r31
+$PIC_pcrel$6
+        MTSP    %r31,%sr0
+        .CALL ARGW0=GR,ARGW1=GR,ARGW2=GR,ARGW3=GR,RTNVAL=GR
+;in=22-26;out=28;
+        BE,L    0(%sr0,%r1),%r31
+        COPY    %r31,%r2
+
+        LDW     -32(%r30),%r19
+        COPY    %r3,%r30              ; restore saved stack ptr
+
+        LDW          -148(%sp),%rp
+        BVE             (%rp)
+  .EXIT
+        LDW,MB       -128(%sp),%r3
+
+  .PROCEND  ;in=23,24,25,26;
+
+  .ALIGN  8
+  .SPACE  $TEXT$
+  .SUBSPA $CODE$
+  .IMPORT $$dyncall_external,MILLICODE
+  .IMPORT invoke_count_bytes,CODE
+  .IMPORT invoke_copy_to_stack,CODE
+  .EXPORT XPTC_InvokeByIndex,ENTRY,PRIV_LEV=3,ARGW0=GR,ARGW1=GR,ARGW2=GR,ARGW3=GR,RTNVAL=GR,LONG_RETURN
+  .END
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_parisc_linux.s b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_parisc_linux.s
new file mode 100644
index 000000000..7a207addf
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_parisc_linux.s
@@ -0,0 +1,108 @@
+/* -*- Mode: asm; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * Version: MPL 1.1
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+  .LEVEL 1.1
+  .text
+  .align 4
+
+framesz:
+  .equ 128
+
+.globl NS_InvokeByIndex
+  .type NS_InvokeByIndex, @function
+
+
+NS_InvokeByIndex:
+  .PROC
+  .CALLINFO FRAME=72, CALLER,SAVE_RP, SAVE_SP, ENTRY_GR=3
+  .ENTRY
+
+; frame marker takes 48 bytes,
+; register spill area takes 8 bytes,
+; local stack area takes 72 bytes result in 128 bytes total
+
+        STW          %rp,-20(%sp)
+        STW,MA       %r3,128(%sp)
+
+        LDO     -framesz(%r30),%r28
+        STW     %r28,-4(%r30)       ; save previous sp
+        STW     %r19,-32(%r30)
+
+        STW     %r26,-36-framesz(%r30)  ; save argument registers in
+        STW     %r25,-40-framesz(%r30)  ; in PREVIOUS frame
+        STW     %r24,-44-framesz(%r30)  ;
+        STW     %r23,-48-framesz(%r30)  ;
+
+        .CALL   ARGW0=GR,ARGW1=GR,ARGW2=GR ;in=24,25,26;out=28
+        BL    invoke_count_bytes,%r31
+        COPY    %r31,%r2
+
+        CMPIB,>=        0,%r28, .+76
+        COPY    %r30,%r3            ; copy stack ptr to saved stack ptr
+        ADD     %r30,%r28,%r30      ; extend stack frame
+        LDW     -4(%r3),%r28        ; move frame
+        STW     %r28,-4(%r30)
+        LDW     -8(%r3),%r28
+        STW     %r28,-8(%r30)
+        LDW     -12(%r3),%r28
+        STW     %r28,-12(%r30)
+        LDW     -16(%r3),%r28
+        STW     %r28,-16(%r30)
+        LDW     -20(%r3),%r28
+        STW     %r28,-20(%r30)
+        LDW     -24(%r3),%r28
+        STW     %r28,-24(%r30)
+        LDW     -28(%r3),%r28
+        STW     %r28,-28(%r30)
+        LDW     -32(%r3),%r28
+        STW     %r28,-32(%r30)
+
+        LDO     -40(%r30),%r26         ; load copy address
+        LDW     -44-framesz(%r3),%r25  ; load rest of 2 arguments
+        LDW     -48-framesz(%r3),%r24  ;
+
+        LDW     -32(%r30),%r19 ; shared lib call destroys r19; reload
+        .CALL   ARGW0=GR,ARGW1=GR,ARGW2=GR ;in=24,25,26
+        BL    invoke_copy_to_stack,%r31
+        COPY    %r31,%r2
+
+        LDO     -48(%r30),%r20
+        EXTRW,U,= %r28,31,1,%r22
+        FLDD    0(%r20),%fr7  ; load double arg 1
+        EXTRW,U,= %r28,30,1,%r22
+        FLDW    8(%r20),%fr5L ; load float arg 1
+        EXTRW,U,= %r28,29,1,%r22
+        FLDW    4(%r20),%fr6L ; load float arg 2
+        EXTRW,U,= %r28,28,1,%r22
+        FLDW    0(%r20),%fr7L ; load float arg 3
+
+        LDW     -36-framesz(%r3),%r26  ; load ptr to 'that'
+        LDW     -40(%r30),%r25  ; load the rest of dispatch argument registers
+        LDW     -44(%r30),%r24
+        LDW     -48(%r30),%r23
+
+        LDW     -36-framesz(%r3),%r20  ; load vtable addr
+        LDW     -40-framesz(%r3),%r28  ; load index
+        LDW     0(%r20),%r20    ; follow vtable
+        SH2ADDL %r28,%r20,%r28  ; add 4*index to vtable entry
+        LDW     0(%r28),%r22    ; load vtable entry
+
+        .CALL ARGW0=GR,ARGW1=GR,ARGW2=GR,ARGW3=GR,RTNVAL=GR ;in=22-26;out=28;
+        BL    $$dyncall,%r31
+        COPY    %r31,%r2
+
+        LDW     -32(%r30),%r19
+        COPY    %r3,%r30              ; restore saved stack ptr
+
+        LDW          -148(%sp),%rp
+        LDWM       -128(%sp),%r3
+        BV,N             (%rp)
+        NOP
+  .EXIT
+  .PROCEND  ;in=23,24,25,26;
+  .SIZE NS_InvokeByIndex, .-NS_InvokeByIndex
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc64_linux.S b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc64_linux.S
new file mode 100644
index 000000000..37211c885
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc64_linux.S
@@ -0,0 +1,167 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+.set r0,0; .set r1,1; .set r2,2; .set r3,3; .set r4,4
+.set r5,5; .set r6,6; .set r7,7; .set r8,8; .set r9,9
+.set r10,10; .set r11,11; .set r12,12; .set r13,13; .set r14,14
+.set r15,15; .set r16,16; .set r17,17; .set r18,18; .set r19,19
+.set r20,20; .set r21,21; .set r22,22; .set r23,23; .set r24,24
+.set r25,25; .set r26,26; .set r27,27; .set r28,28; .set r29,29
+.set r30,30; .set r31,31
+.set f0,0; .set f1,1; .set f2,2; .set f3,3; .set f4,4
+.set f5,5; .set f6,6; .set f7,7; .set f8,8; .set f9,9
+.set f10,10; .set f11,11; .set f12,12; .set f13,13; .set f14,14
+.set f15,15; .set f16,16; .set f17,17; .set f18,18; .set f19,19
+.set f20,20; .set f21,21; .set f22,22; .set f23,23; .set f24,24
+.set f25,25; .set f26,26; .set f27,27; .set f28,28; .set f29,29
+.set f30,30; .set f31,31
+
+# The ABI defines a fixed stack frame area of 4 doublewords (ELFv2)
+# or 6 doublewords (ELFv1); the last of these doublewords is used
+# as TOC pointer save area.  The fixed area is followed by a parameter
+# save area of 8 doublewords (used for vararg routines), followed
+# by space for parameters passed on the stack.
+#
+# We set STACK_TOC to the offset of the TOC pointer save area, and
+# STACK_PARAMS to the offset of the first on-stack parameter.
+
+#if _CALL_ELF == 2
+#define STACK_TOC      24
+#define STACK_PARAMS   96
+#else
+#define STACK_TOC      40
+#define STACK_PARAMS   112
+#endif
+
+#
+# NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+#                    uint32_t paramCount, nsXPTCVariant* params)
+#
+
+#if _CALL_ELF == 2
+        .section ".text"
+        .type   NS_InvokeByIndex,@function
+        .globl  NS_InvokeByIndex
+        .align 2
+NS_InvokeByIndex:
+0:      addis 2,12,(.TOC.-0b)@ha
+        addi 2,2,(.TOC.-0b)@l
+        .localentry NS_InvokeByIndex,.-NS_InvokeByIndex
+#else
+        .section ".toc","aw"
+        .section ".text"
+        .align 2
+        .globl  NS_InvokeByIndex
+        .section ".opd","aw"
+        .align 3
+NS_InvokeByIndex:
+        .quad   .NS_InvokeByIndex,.TOC.@tocbase
+        .previous
+        .type   NS_InvokeByIndex,@function
+.NS_InvokeByIndex:
+#endif
+        mflr    0
+        std     0,16(r1)
+
+        std     r29,-24(r1)
+        std     r30,-16(r1)
+        std     r31,-8(r1)
+
+        mr      r29,r3                  # Save 'that' in r29
+        mr      r30,r4                  # Save 'methodIndex' in r30
+        mr      r31,r1                  # Save old frame
+
+        # Allocate stack frame with space for params. Since at least the
+        # first 7 parameters (not including 'that') will be in registers,
+        # we don't actually need stack space for those. We must ensure
+        # that the stack remains 16-byte aligned.
+        #
+        #  | (fixed area + |                | 7 GP | 13 FP | 3 NV |
+        #  |  param. save) |(params)........| regs | regs  | regs |
+        # (r1)......(+STACK_PARAMS)...  (-23*8).(-16*8).(-3*8)..(r31)
+
+        # +stack frame, -unused stack params, +regs storage, +1 for alignment
+        addi    r7,r5,((STACK_PARAMS/8)-7+7+13+3+1)
+        rldicr  r7,r7,3,59              # multiply by 8 and mask with ~15
+        neg     r7,r7
+        stdux   r1,r1,r7
+
+
+        # Call invoke_copy_to_stack(uint64_t* gpregs, double* fpregs,
+        #                           uint32_t paramCount, nsXPTCVariant* s, 
+        #                           uint64_t* d))
+
+        # r5, r6 are passed through intact (paramCount, params)
+        # r7 (d) has to be r1+STACK_PARAMS
+        #        -- where parameters are passed on the stack.
+        # r3, r4 are above that, easier to address from r31 than from r1
+
+        subi    r3,r31,(23*8)           # r3 --> GPRS
+        subi    r4,r31,(16*8)           # r4 --> FPRS
+        addi    r7,r1,STACK_PARAMS      # r7 --> params
+        bl      invoke_copy_to_stack
+        nop
+
+        # Set up to invoke function
+
+        ld      r9,0(r29)               # vtable (r29 is 'that')
+        mr      r3,r29                  # self is first arg, obviously
+
+        sldi    r30,r30,3               # Find function descriptor 
+        add     r9,r9,r30
+        ld      r12,0(r9)
+
+        std     r2,STACK_TOC(r1)        # Save r2 (TOC pointer)
+
+#if _CALL_ELF == 2
+        mtctr   r12
+#else
+        ld      r0,0(r12)               # Actual address from fd.
+        mtctr   0
+        ld      r11,16(r12)             # Environment pointer from fd.
+        ld      r2,8(r12)               # TOC pointer from fd.
+#endif
+
+        # Load FP and GP registers as required
+        ld      r4, -(23*8)(r31) 
+        ld      r5, -(22*8)(r31) 
+        ld      r6, -(21*8)(r31) 
+        ld      r7, -(20*8)(r31) 
+        ld      r8, -(19*8)(r31) 
+        ld      r9, -(18*8)(r31) 
+        ld      r10, -(17*8)(r31) 
+
+        lfd     f1, -(16*8)(r31)
+        lfd     f2, -(15*8)(r31)
+        lfd     f3, -(14*8)(r31)
+        lfd     f4, -(13*8)(r31)
+        lfd     f5, -(12*8)(r31)
+        lfd     f6, -(11*8)(r31)
+        lfd     f7, -(10*8)(r31)
+        lfd     f8, -(9*8)(r31)
+        lfd     f9, -(8*8)(r31)
+        lfd     f10, -(7*8)(r31)
+        lfd     f11, -(6*8)(r31)
+        lfd     f12, -(5*8)(r31)
+        lfd     f13, -(4*8)(r31)
+
+        bctrl                           # Do it
+
+        ld      r2,STACK_TOC(r1)        # Load our own TOC pointer
+        ld      r1,0(r1)                # Revert stack frame
+        ld      0,16(r1)                # Reload lr
+        ld      29,-24(r1)              # Restore NVGPRS
+        ld      30,-16(r1)
+        ld      31,-8(r1)
+        mtlr    0
+        blr
+
+#if _CALL_ELF == 2
+        .size   NS_InvokeByIndex,.-NS_InvokeByIndex
+#else
+        .size   NS_InvokeByIndex,.-.NS_InvokeByIndex
+#endif
+
+        # Magic indicating no need for an executable stack
+        .section .note.GNU-stack, "", @progbits ; .previous
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_aix.s b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_aix.s
new file mode 100644
index 000000000..eb6b6661d
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_aix.s
@@ -0,0 +1,129 @@
+#
+# -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+.set r0,0; .set sp,1; .set RTOC,2; .set r3,3; .set r4,4
+.set r5,5; .set r6,6; .set r7,7; .set r8,8; .set r9,9
+.set r10,10; .set r11,11; .set r12,12; .set r13,13; .set r14,14
+.set r15,15; .set r16,16; .set r17,17; .set r18,18; .set r19,19
+.set r20,20; .set r21,21; .set r22,22; .set r23,23; .set r24,24
+.set r25,25; .set r26,26; .set r27,27; .set r28,28; .set r29,29
+.set r30,30; .set r31,31
+.set f0,0; .set f1,1; .set f2,2; .set f3,3; .set f4,4
+.set f5,5; .set f6,6; .set f7,7; .set f8,8; .set f9,9
+.set f10,10; .set f11,11; .set f12,12; .set f13,13; .set f14,14
+.set f15,15; .set f16,16; .set f17,17; .set f18,18; .set f19,19
+.set f20,20; .set f21,21; .set f22,22; .set f23,23; .set f24,24
+.set f25,25; .set f26,26; .set f27,27; .set f28,28; .set f29,29
+.set f30,30; .set f31,31
+.set BO_IF,12
+.set CR0_EQ,2
+
+
+
+        .rename H.10.NO_SYMBOL{PR},""
+        .rename H.18.NS_InvokeByIndex{TC},"NS_InvokeByIndex"
+
+
+# .text section
+
+        .csect  H.10.NO_SYMBOL{PR}
+        .globl  .NS_InvokeByIndex
+        .globl  NS_InvokeByIndex{DS}
+        .extern .invoke_copy_to_stack
+        .extern ._ptrgl{PR}
+
+
+#
+#   NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+#                   uint32_t paramCount, nsXPTCVariant* params)
+#
+
+.NS_InvokeByIndex:
+		mflr	r0
+		stw	r31,-4(sp)
+#
+# save off the incoming values in the caller's parameter area
+#		
+		stw	r3,24(sp)		# that
+		stw	r4,28(sp)		# methodIndex
+		stw	r5,32(sp)		# paramCount
+		stw	r6,36(sp)		# params
+		stw	r0,8(sp)
+		stwu	sp,-136(sp)		#  = 24 for linkage area,  8 * 13 for fprData area, 8 for saved registers
+
+# prepare args for 'invoke_copy_to_stack' call
+#		
+		lwz	r4,168(sp)		# paramCount
+		lwz	r5,172(sp)		# params
+		mr	r6,sp			# fprData
+		slwi	r3,r4,3			# number of bytes of stack required
+								# at most 8*paramCount
+		addi	r3,r3,28		# linkage area
+		mr	r31,sp			# save original stack top
+		subfc	sp,r3,sp		# bump the stack
+		addi	r3,sp,28		# parameter pointer excludes linkage area size + 'this'
+		
+		bl	.invoke_copy_to_stack
+		nop
+		
+		lfd	f1,0(r31)		# Restore floating point registers	
+		lfd	f2,8(r31)				
+		lfd	f3,16(r31)				
+		lfd	f4,24(r31)				
+		lfd	f5,32(r31)				
+		lfd	f6,40(r31)				
+		lfd	f7,48(r31)				
+		lfd	f8,56(r31)				
+		lfd	f9,64(r31)				
+		lfd	f10,72(r31)				
+		lfd	f11,80(r31)				
+		lfd	f12,88(r31)				
+		lfd	f13,96(r31)				
+		
+		lwz	r3,160(r31)		# that
+		lwz	r4,0(r3)		# get vTable from 'that'
+		lwz	r5,164(r31)		# methodIndex
+		slwi	r5,r5,3			# methodIndex * 8
+		addi	r5,r5,8			# step over junk at start of vTable !
+		lwzx	r11,r5,r4		# get function pointer
+
+		addi	r5,r5,4    	 	# We need to manually adjust the 'that' pointer, this is CFRONT based
+		lwzx	r5,r4,r5 		# offset = r4(vtable) + r5(methodIndex offset) - 4 
+		add	r3,r5,r3		# adjust 'that' r3 = r3 + r5
+		
+		lwz	r4,28(sp)
+		lwz	r5,32(sp)
+		lwz	r6,36(sp)
+		lwz	r7,40(sp)
+		lwz	r8,44(sp)
+		lwz	r9,48(sp)
+		lwz	r10,52(sp)
+
+		bl      ._ptrgl{PR}
+		nop		
+		
+		mr      sp,r31
+		lwz	r0,144(sp)
+		addi    sp,sp,136
+		mtlr    r0
+		lwz     r31,-4(sp)
+	        blr
+
+
+# .data section
+
+        .toc                            # 0x00000038
+T.18.NS_InvokeByIndex:
+        .tc     H.18.NS_InvokeByIndex{TC},NS_InvokeByIndex{DS}
+
+        .csect  NS_InvokeByIndex{DS}
+        .long   .NS_InvokeByIndex     # "\0\0\0\0"
+        .long   TOC{TC0}                # "\0\0\0008"
+        .long   0x00000000              # "\0\0\0\0"
+# End   csect   NS_InvokeByIndex{DS}
+
+# .bss section	
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_aix64.s b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_aix64.s
new file mode 100644
index 000000000..722583de5
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_aix64.s
@@ -0,0 +1,128 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+.set r0,0; .set sp,1; .set RTOC,2; .set r3,3; .set r4,4
+.set r5,5; .set r6,6; .set r7,7; .set r8,8; .set r9,9
+.set r10,10; .set r11,11; .set r12,12; .set r13,13; .set r14,14
+.set r15,15; .set r16,16; .set r17,17; .set r18,18; .set r19,19
+.set r20,20; .set r21,21; .set r22,22; .set r23,23; .set r24,24
+.set r25,25; .set r26,26; .set r27,27; .set r28,28; .set r29,29
+.set r30,30; .set r31,31
+.set f0,0; .set f1,1; .set f2,2; .set f3,3; .set f4,4
+.set f5,5; .set f6,6; .set f7,7; .set f8,8; .set f9,9
+.set f10,10; .set f11,11; .set f12,12; .set f13,13; .set f14,14
+.set f15,15; .set f16,16; .set f17,17; .set f18,18; .set f19,19
+.set f20,20; .set f21,21; .set f22,22; .set f23,23; .set f24,24
+.set f25,25; .set f26,26; .set f27,27; .set f28,28; .set f29,29
+.set f30,30; .set f31,31
+.set BO_IF,12
+.set CR0_EQ,2
+
+        .rename H.10.NO_SYMBOL{PR},""
+        .rename H.18.NS_InvokeByIndex{TC},"NS_InvokeByIndex"
+
+
+# .text section
+
+        .csect  H.10.NO_SYMBOL{PR}
+        .globl  .NS_InvokeByIndex
+        .globl  NS_InvokeByIndex{DS}
+        .extern .invoke_copy_to_stack
+        .extern ._ptrgl{PR}
+
+#
+#   NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+#                      uint32_t paramCount, nsXPTCVariant* params)
+#
+
+.NS_InvokeByIndex:
+        mflr    r0
+        std     r31,-8(sp)
+#
+# save off the incoming values in the caller's parameter area
+#		
+        std     r3,48(sp)       # that
+        std     r4,56(sp)       # methodIndex
+        std     r5,64(sp)       # paramCount
+        std     r6,72(sp)       # params
+	std     r0,16(sp)
+	stdu    sp,-168(sp)     # 2*24=48 for linkage area, 
+                                # 8*13=104 for fprData area
+                                #      16 for saved registers
+
+# prepare args for 'invoke_copy_to_stack' call
+#		
+        ld      r4,232(sp)      # paramCount (168+8+56)
+        ld      r5,240(sp)      # params
+        mr      r6,sp           # fprData
+        sldi    r3,r4,3         # number of bytes of stack required
+                                # is at most numParams*8
+        addi    r3,r3,56        # linkage area (48) + this (8)
+        mr      r31,sp          # save original stack top
+        subfc   sp,r3,sp        # bump the stack
+        addi    r3,sp,56        # parameter pointer excludes linkage area
+                                # size + 'this'
+
+        bl      .invoke_copy_to_stack
+        nop
+
+        lfd     f1,0(r31)       # Restore floating point registers	
+	lfd     f2,8(r31)
+        lfd     f3,16(r31)
+        lfd     f4,24(r31)
+        lfd     f5,32(r31)
+        lfd     f6,40(r31)
+        lfd     f7,48(r31)
+        lfd     f8,56(r31)
+        lfd     f9,64(r31)
+        lfd     f10,72(r31)
+        lfd     f11,80(r31)
+        lfd     f12,88(r31)
+        lfd     f13,96(r31)
+		
+        ld      r3,216(r31)     # that (168+48)
+        ld      r4,0(r3)        # get vTable from 'that'
+        ld      r5,224(r31)     # methodIndex (168+56)
+        sldi    r5,r5,3         # methodIndex * 8
+                                # No junk at the start of 64bit vtable !!!
+        ldx     r11,r5,r4       # get function pointer (this jumps
+                                # either to the function if no adjustment
+                                # is needed (displacement = 0), or it 
+                                # jumps to the thunk code, which will jump
+                                # to the function at the end)
+        
+        # No adjustment of the that pointer in 64bit mode, this is done
+        # by the thunk code
+
+        ld      r4,56(sp)
+        ld      r5,64(sp)
+        ld      r6,72(sp)
+        ld      r7,80(sp)
+        ld      r8,88(sp)
+        ld      r9,96(sp)
+        ld      r10,104(sp)
+
+        bl      ._ptrgl{PR}
+        nop
+
+        mr      sp,r31
+        ld      r0,184(sp)      # 168+16
+        addi    sp,sp,168
+        mtlr    r0
+        ld      r31,-8(sp)
+        blr
+
+# .data section
+
+        .toc                            # 0x00000038
+T.18.NS_InvokeByIndex:
+        .tc     H.18.NS_InvokeByIndex{TC},NS_InvokeByIndex{DS}
+
+        .csect  NS_InvokeByIndex{DS}
+        .llong  .NS_InvokeByIndex     # "\0\0\0\0"
+        .llong  TOC{TC0}                # "\0\0\0008"
+        .llong  0x00000000              # "\0\0\0\0"
+# End   csect   NS_InvokeByIndex{DS}
+
+# .bss section
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_ibmobj_aix.s b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_ibmobj_aix.s
new file mode 100644
index 000000000..414a6536f
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_ibmobj_aix.s
@@ -0,0 +1,124 @@
+#
+# -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+.set r0,0; .set sp,1; .set RTOC,2; .set r3,3; .set r4,4
+.set r5,5; .set r6,6; .set r7,7; .set r8,8; .set r9,9
+.set r10,10; .set r11,11; .set r12,12; .set r13,13; .set r14,14
+.set r15,15; .set r16,16; .set r17,17; .set r18,18; .set r19,19
+.set r20,20; .set r21,21; .set r22,22; .set r23,23; .set r24,24
+.set r25,25; .set r26,26; .set r27,27; .set r28,28; .set r29,29
+.set r30,30; .set r31,31
+.set f0,0; .set f1,1; .set f2,2; .set f3,3; .set f4,4
+.set f5,5; .set f6,6; .set f7,7; .set f8,8; .set f9,9
+.set f10,10; .set f11,11; .set f12,12; .set f13,13; .set f14,14
+.set f15,15; .set f16,16; .set f17,17; .set f18,18; .set f19,19
+.set f20,20; .set f21,21; .set f22,22; .set f23,23; .set f24,24
+.set f25,25; .set f26,26; .set f27,27; .set f28,28; .set f29,29
+.set f30,30; .set f31,31
+.set BO_IF,12
+.set CR0_EQ,2
+
+
+
+        .rename H.10.NO_SYMBOL{PR},""
+        .rename H.18.NS_InvokeByIndex{TC},"NS_InvokeByIndex"
+
+
+# .text section
+
+        .csect  H.10.NO_SYMBOL{PR}
+        .globl  .NS_InvokeByIndex
+        .globl  NS_InvokeByIndex{DS}
+        .extern .invoke_copy_to_stack
+        .extern ._ptrgl{PR}
+
+
+#
+#   NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+#                   uint32_t paramCount, nsXPTCVariant* params)
+#
+
+.NS_InvokeByIndex:
+		mflr	r0
+		stw	r31,-4(sp)
+#
+# save off the incoming values in the caller's parameter area
+#		
+		stw	r3,24(sp)		# that
+		stw	r4,28(sp)		# methodIndex
+		stw	r5,32(sp)		# paramCount
+		stw	r6,36(sp)		# params
+		stw	r0,8(sp)
+		stwu	sp,-136(sp)		#  = 24 for linkage area,  8 * 13 for fprData area, 8 for saved registers
+
+# prepare args for 'invoke_copy_to_stack' call
+#		
+		lwz	r4,168(sp)		# paramCount
+		lwz	r5,172(sp)		# params
+		mr	r6,sp			# fprData
+		slwi	r3,r4,3			# number of bytes of stack required
+								# at most 8*paramCount
+		addi	r3,r3,28		# linkage area
+		mr	r31,sp			# save original stack top
+		subfc	sp,r3,sp		# bump the stack
+		addi	r3,sp,28		# parameter pointer excludes linkage area size + 'this'
+		
+		bl	.invoke_copy_to_stack
+		nop
+		
+		lfd	f1,0(r31)		# Restore floating point registers	
+		lfd	f2,8(r31)				
+		lfd	f3,16(r31)				
+		lfd	f4,24(r31)				
+		lfd	f5,32(r31)				
+		lfd	f6,40(r31)				
+		lfd	f7,48(r31)				
+		lfd	f8,56(r31)				
+		lfd	f9,64(r31)				
+		lfd	f10,72(r31)				
+		lfd	f11,80(r31)				
+		lfd	f12,88(r31)				
+		lfd	f13,96(r31)				
+		
+		lwz	r3,160(r31)		# that
+		lwz	r4,0(r3)		# get vTable from 'that'
+		lwz	r5,164(r31)		# methodIndex
+		slwi	r5,r5,2			# methodIndex * 4
+		lwzx	r11,r5,r4		# get function pointer
+
+		lwz	r4,28(sp)
+		lwz	r5,32(sp)
+		lwz	r6,36(sp)
+		lwz	r7,40(sp)
+		lwz	r8,44(sp)
+		lwz	r9,48(sp)
+		lwz	r10,52(sp)
+
+		bl      ._ptrgl{PR}
+		nop		
+		
+		mr      sp,r31
+		lwz	r0,144(sp)
+		addi    sp,sp,136
+		mtlr    r0
+		lwz     r31,-4(sp)
+	        blr
+
+
+# .data section
+
+        .toc                            # 0x00000038
+T.18.NS_InvokeByIndex:
+        .tc     H.18.NS_InvokeByIndex{TC},NS_InvokeByIndex{DS}
+
+        .csect  NS_InvokeByIndex{DS}
+        .long   .NS_InvokeByIndex     # "\0\0\0\0"
+        .long   TOC{TC0}                # "\0\0\0008"
+        .long   0x00000000              # "\0\0\0\0"
+# End   csect   NS_InvokeByIndex{DS}
+
+# .bss section	
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_linux.S b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_linux.S
new file mode 100644
index 000000000..e87382286
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_linux.S
@@ -0,0 +1,98 @@
+// -*- Mode: Asm -*-
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+.set r0,0; .set sp,1; .set RTOC,2; .set r3,3; .set r4,4
+.set r5,5; .set r6,6; .set r7,7; .set r8,8; .set r9,9
+.set r10,10; .set r11,11; .set r12,12; .set r13,13; .set r14,14
+.set r15,15; .set r16,16; .set r17,17; .set r18,18; .set r19,19
+.set r20,20; .set r21,21; .set r22,22; .set r23,23; .set r24,24
+.set r25,25; .set r26,26; .set r27,27; .set r28,28; .set r29,29
+.set r30,30; .set r31,31
+.set f0,0; .set f1,1; .set f2,2; .set f3,3; .set f4,4
+.set f5,5; .set f6,6; .set f7,7; .set f8,8; .set f9,9
+.set f10,10; .set f11,11; .set f12,12; .set f13,13; .set f14,14
+.set f15,15; .set f16,16; .set f17,17; .set f18,18; .set f19,19
+.set f20,20; .set f21,21; .set f22,22; .set f23,23; .set f24,24
+.set f25,25; .set f26,26; .set f27,27; .set f28,28; .set f29,29
+.set f30,30; .set f31,31
+		      
+        .section ".text"
+	.align 2
+	.globl NS_InvokeByIndex
+	.type  NS_InvokeByIndex,@function
+
+//
+// NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+//                  uint32_t paramCount, nsXPTCVariant* params)
+//
+
+NS_InvokeByIndex:
+	stwu    sp,-32(sp)			// setup standard stack frame
+	mflr    r0				// save LR
+	stw     r3,8(sp)			// r3 <= that
+	stw     r4,12(sp)			// r4 <= methodIndex
+	stw     r30,16(sp)
+	stw     r31,20(sp)
+
+	stw     r0,36(sp)			// store LR backchain
+	mr      r31,sp
+
+	rlwinm  r10,r5,3,0,27			// r10 = (ParamCount * 2 * 4) & ~0x0f
+	addi    r0,r10,96			// reserve stack for GPR and FPR register save area r0 = r10 + 96
+	lwz     r9,0(sp)			// r9 = backchain
+	neg     r0,r0
+	stwux   r9,sp,r0			// reserve stack space and save SP backchain
+
+	addi    r3,sp,8				// r3 <= args
+	mr      r4,r5				// r4 <= paramCount
+	mr      r5,r6				// r5 <= params
+	add     r6,r3,r10			// r6 <= gpregs ( == args + r10 )
+	mr      r30,r6				// store in r30 for use later...
+#ifndef __NO_FPRS__
+	addi    r7,r6,32			// r7 <= fpregs ( == gpregs + 32 )
+#else
+	li	r7, 0
+#endif
+
+	bl      invoke_copy_to_stack@local	// (args, paramCount, params, gpregs, fpregs)
+#ifndef __NO_FPRS__
+	lfd     f1,32(r30)			// load FP registers with method parameters
+	lfd     f2,40(r30)   
+	lfd     f3,48(r30)  
+	lfd     f4,56(r30)  
+	lfd     f5,64(r30)  
+	lfd     f6,72(r30)  
+	lfd     f7,80(r30)  
+	lfd     f8,88(r30)
+#endif
+	lwz     r3,8(r31)			// r3 <= that
+	lwz     r4,12(r31)			// r4 <= methodIndex
+	lwz     r5,0(r3)			// r5 <= vtable ( == *that )
+	slwi    r4,r4,2				// convert to offset ( *= 4 )
+	lwzx    r0,r5,r4			// r0 <= methodpointer ( == vtable + offset )
+
+        lwz     r4,4(r30)			// load GP regs with method parameters
+	lwz     r5,8(r30)   
+	lwz     r6,12(r30)  
+	lwz     r7,16(r30)  
+	lwz     r8,20(r30)  
+	lwz     r9,24(r30)  
+	lwz     r10,28(r30)
+
+	mtlr    r0				// copy methodpointer to LR    
+	blrl					// call method
+	
+	lwz     r30,16(r31)			// restore r30 & r31
+	lwz     r31,20(r31)
+	
+	lwz     r11,0(sp)			// clean up the stack
+	lwz     r0,4(r11)
+	mtlr    r0
+	mr      sp,r11
+	blr
+
+/* Magic indicating no need for an executable stack */
+.section .note.GNU-stack, "", @progbits ; .previous
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_netbsd.s b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_netbsd.s
new file mode 100644
index 000000000..33650f399
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_netbsd.s
@@ -0,0 +1,95 @@
+# -*- Mode: Asm -*-
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+.set r0,0; .set sp,1; .set RTOC,2; .set r3,3; .set r4,4
+.set r5,5; .set r6,6; .set r7,7; .set r8,8; .set r9,9
+.set r10,10; .set r11,11; .set r12,12; .set r13,13; .set r14,14
+.set r15,15; .set r16,16; .set r17,17; .set r18,18; .set r19,19
+.set r20,20; .set r21,21; .set r22,22; .set r23,23; .set r24,24
+.set r25,25; .set r26,26; .set r27,27; .set r28,28; .set r29,29
+.set r30,30; .set r31,31
+.set f0,0; .set f1,1; .set f2,2; .set f3,3; .set f4,4
+.set f5,5; .set f6,6; .set f7,7; .set f8,8; .set f9,9
+.set f10,10; .set f11,11; .set f12,12; .set f13,13; .set f14,14
+.set f15,15; .set f16,16; .set f17,17; .set f18,18; .set f19,19
+.set f20,20; .set f21,21; .set f22,22; .set f23,23; .set f24,24
+.set f25,25; .set f26,26; .set f27,27; .set f28,28; .set f29,29
+.set f30,30; .set f31,31
+		      
+        .section ".text"
+	.align 2
+	.globl XPTC_InvokeByIndex
+	.type  XPTC_InvokeByIndex,@function
+
+#
+# XPTC_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+#                    uint32_t paramCount, nsXPTCVariant* params)
+#
+
+XPTC_InvokeByIndex:
+	stwu    sp,-32(sp)			# setup standard stack frame
+	mflr    r0				# save LR
+	stw     r3,8(sp)			# r3 <= that
+	stw     r4,12(sp)			# r4 <= methodIndex
+	stw     r30,16(sp)
+	stw     r31,20(sp)
+
+	stw     r0,36(sp)			# store LR backchain
+	mr      r31,sp
+
+	rlwinm  r10,r5,3,0,27			# r10 = (ParamCount * 2 * 4) & ~0x0f
+	addi    r0,r10,96			# reserve stack for GPR and FPR register save area r0 = r10 + 96
+	lwz     r9,0(sp)			# r9 = backchain
+	neg     r0,r0
+	stwux   r9,sp,r0			# reserve stack sapce and save SP backchain
+	
+	addi    r3,sp,8				# r3 <= args
+	mr      r4,r5				# r4 <= paramCount
+	mr      r5,r6				# r5 <= params
+	add     r6,r3,r10			# r6 <= gpregs ( == args + r10 )
+	mr      r30,r6				# store in r30 for use later...
+	addi    r7,r6,32			# r7 <= fpregs ( == gpregs + 32 )
+
+	bl      invoke_copy_to_stack@local	# (args, paramCount, params, gpregs, fpregs)
+
+	lfd     f1,32(r30)			# load FP registers with method parameters
+	lfd     f2,40(r30)   
+	lfd     f3,48(r30)  
+	lfd     f4,56(r30)  
+	lfd     f5,64(r30)  
+	lfd     f6,72(r30)  
+	lfd     f7,80(r30)  
+	lfd     f8,88(r30)
+
+	lwz     r3,8(r31)			# r3 <= that
+	lwz     r4,12(r31)			# r4 <= methodIndex
+	lwz     r5,0(r3)			# r5 <= vtable ( == *that )
+	slwi    r4,r4,3				# convert to offset ( *= 8 )
+	addi	r4,r4,8				# skip first two vtable entries
+	add	r4,r4,r5
+	lhz	r0,0(r4)			# virtual base offset
+	extsh	r0,r0
+	add	r3,r3,r0
+	lwz     r0,4(r4)			# r0 <= methodpointer ( == vtable + offset )
+
+        lwz     r4,4(r30)			# load GP regs with method parameters
+	lwz     r5,8(r30)   
+	lwz     r6,12(r30)  
+	lwz     r7,16(r30)  
+	lwz     r8,20(r30)  
+	lwz     r9,24(r30)  
+	lwz     r10,28(r30)
+
+	mtlr    r0				# copy methodpointer to LR    
+	blrl					# call method
+	
+	lwz     r30,16(r31)			# restore r30 & r31
+	lwz     r31,20(r31)
+	
+	lwz     r11,0(sp)			# clean up the stack
+	lwz     r0,4(r11)
+	mtlr    r0
+	mr      sp,r11
+	blr
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_openbsd.S b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_openbsd.S
new file mode 100644
index 000000000..f02c0b220
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_openbsd.S
@@ -0,0 +1,94 @@
+// -*- Mode: Asm -*-
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+.set r0,0; .set sp,1; .set RTOC,2; .set r3,3; .set r4,4
+.set r5,5; .set r6,6; .set r7,7; .set r8,8; .set r9,9
+.set r10,10; .set r11,11; .set r12,12; .set r13,13; .set r14,14
+.set r15,15; .set r16,16; .set r17,17; .set r18,18; .set r19,19
+.set r20,20; .set r21,21; .set r22,22; .set r23,23; .set r24,24
+.set r25,25; .set r26,26; .set r27,27; .set r28,28; .set r29,29
+.set r30,30; .set r31,31
+.set f0,0; .set f1,1; .set f2,2; .set f3,3; .set f4,4
+.set f5,5; .set f6,6; .set f7,7; .set f8,8; .set f9,9
+.set f10,10; .set f11,11; .set f12,12; .set f13,13; .set f14,14
+.set f15,15; .set f16,16; .set f17,17; .set f18,18; .set f19,19
+.set f20,20; .set f21,21; .set f22,22; .set f23,23; .set f24,24
+.set f25,25; .set f26,26; .set f27,27; .set f28,28; .set f29,29
+.set f30,30; .set f31,31
+
+	.section ".text"
+	.align 2
+	.globl NS_InvokeByIndex
+	.type  NS_InvokeByIndex,@function
+
+//
+// NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+//                    uint32_t paramCount, nsXPTCVariant* params)
+//
+
+NS_InvokeByIndex:
+	stwu	sp,-32(sp)			// setup standard stack frame
+	mflr	r0				// save LR
+	stw	r3,8(sp)			// r3 <= that
+	stw	r4,12(sp)			// r4 <= methodIndex
+	stw	r30,16(sp)
+	stw	r31,20(sp)
+
+	stw	r0,36(sp)			// store LR backchain
+	mr	r31,sp
+
+	rlwinm	r10,r5,3,0,27			// r10 = (ParamCount * 2 * 4) & ~0x0f
+	addi	r0,r10,96			// reserve stack for GPR and FPR register save area r0 = r10 + 96
+	lwz	r9,0(sp)			// r9 = backchain
+	neg	r0,r0
+	stwux	r9,sp,r0			// reserve stack space and save SP backchain
+
+	addi	r3,sp,8				// r3 <= args
+	mr	r4,r5				// r4 <= paramCount
+	mr	r5,r6				// r5 <= params
+	add	r6,r3,r10			// r6 <= gpregs ( == args + r10 )
+	mr	r30,r6				// store in r30 for use later...
+	addi	r7,r6,32			// r7 <= fpregs ( == gpregs + 32 )
+
+	bl	invoke_copy_to_stack@local	// (args, paramCount, params, gpregs, fpregs)
+
+	lfd	f1,32(r30)			// load FP registers with method parameters
+	lfd	f2,40(r30)
+	lfd	f3,48(r30)
+	lfd	f4,56(r30)
+	lfd	f5,64(r30)
+	lfd	f6,72(r30)
+	lfd	f7,80(r30)
+	lfd	f8,88(r30)
+
+	lwz	r3,8(r31)			// r3 <= that
+	lwz	r4,12(r31)			// r4 <= methodIndex
+	lwz	r5,0(r3)			// r5 <= vtable ( == *that )
+	slwi	r4,r4,2				// convert to offset ( *= 4 )
+	lwzx	r0,r5,r4			// r0 <= methodpointer ( == vtable + offset )
+
+	lwz	r4,4(r30)			// load GP regs with method parameters
+	lwz	r5,8(r30)
+	lwz	r6,12(r30)
+	lwz	r7,16(r30)
+	lwz	r8,20(r30)
+	lwz	r9,24(r30)
+	lwz	r10,28(r30)
+
+	mtlr	r0				// copy methodpointer to LR
+	blrl					// call method
+
+	lwz	r30,16(r31)			// restore r30 & r31
+	lwz	r31,20(r31)
+
+	lwz	r11,0(sp)			// clean up the stack
+	lwz	r0,4(r11)
+	mtlr	r0
+	mr	sp,r11
+	blr
+
+// Magic indicating no need for an executable stack
+.section .note.GNU-stack, "", @progbits ; .previous
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_rhapsody.s b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_rhapsody.s
new file mode 100644
index 000000000..1dc12b2b3
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_ppc_rhapsody.s
@@ -0,0 +1,142 @@
+#
+# -*- Mode: Asm -*-
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# 
+# ** Assumed vtable layout (obtained by disassembling with gdb):
+# ** 4 bytes per vtable entry, skip 0th and 1st entries, so the mapping
+# ** from index to entry is (4 * index) + 8.
+#
+
+.text
+	.align 2
+#
+#   NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+#                    uint32_t paramCount, nsXPTCVariant* params)
+#
+
+.globl __NS_InvokeByIndex	
+__NS_InvokeByIndex:
+	mflr	r0
+	stw	r31,-4(r1)
+#
+# save off the incoming values in the callers parameter area
+#		
+	stw	r3,24(r1)               ; that
+	stw	r4,28(r1)               ; methodIndex
+	stw	r5,32(r1)               ; paramCount
+	stw	r6,36(r1)               ; params
+	stw	r0,8(r1)
+	stwu	r1,-144(r1)             ; 24 for linkage area, 
+                                        ; 8*13 for fprData area,
+                                        ; 8 for saved registers,
+                                        ; 8 to keep stack 16-byte aligned
+
+# set up for and call 'invoke_count_words' to get new stack size
+#	
+	mr	r3,r5
+	mr	r4,r6
+
+	stwu	r1,-24(r1)	
+	bl	L_invoke_count_words$stub
+	lwz	r1,0(r1)
+
+# prepare args for 'invoke_copy_to_stack' call
+#		
+	lwz	r4,176(r1)              ; paramCount
+	lwz	r5,180(r1)              ; params
+	mr	r6,r1                   ; fprData
+	slwi	r3,r3,2                 ; number of stack bytes required
+	addi	r3,r3,28                ; linkage area
+	mr	r31,r1                  ; save original stack top
+	sub	r1,r1,r3                ; bump the stack
+	clrrwi	r1,r1,4                 ; keep the stack 16-byte aligned
+	addi	r3,r31,144              ; act like real alloca, so 0(sp) always
+	stw	r3,0(r1)                ;  points back to previous stack frame
+	addi	r3,r1,28                ; parameter pointer excludes linkage area size + 'this'
+	
+# create "temporary" stack frame for _invoke_copy_to_stack to operate in.
+	stwu	r1,-40(r1)
+	bl	L_invoke_copy_to_stack$stub
+# remove temporary stack frame.
+	lwz	r1,0(r1)
+
+	lfd	f1,0(r31)				
+	lfd	f2,8(r31)				
+	lfd	f3,16(r31)				
+	lfd	f4,24(r31)				
+	lfd	f5,32(r31)				
+	lfd	f6,40(r31)				
+	lfd	f7,48(r31)				
+	lfd	f8,56(r31)				
+	lfd	f9,64(r31)				
+	lfd	f10,72(r31)				
+	lfd	f11,80(r31)				
+	lfd	f12,88(r31)				
+	lfd	f13,96(r31)				
+	
+	lwz	r3,168(r31)             ; that
+	lwz	r4,0(r3)                ; get vTable from 'that'
+	lwz	r5,172(r31)             ; methodIndex
+	slwi	r5,r5,2                 ; methodIndex * 4
+	lwzx	r12,r5,r4               ; get function pointer
+
+	lwz	r4,28(r1)
+	lwz	r5,32(r1)
+	lwz	r6,36(r1)
+	lwz	r7,40(r1)
+	lwz	r8,44(r1)
+	lwz	r9,48(r1)
+	lwz	r10,52(r1)
+	
+	mtlr	r12
+	blrl
+	
+	mr      r1,r31
+	lwz	r0,152(r1)
+	addi    r1,r1,144
+	mtlr    r0
+	lwz     r31,-4(r1)
+
+	blr
+
+.picsymbol_stub
+L_invoke_count_words$stub:
+        .indirect_symbol _invoke_count_words
+        mflr r0
+        bcl 20,31,L1$pb
+L1$pb:
+        mflr r11
+        addis r11,r11,ha16(L1$lz-L1$pb)
+        mtlr r0
+        lwz r12,lo16(L1$lz-L1$pb)(r11)
+        mtctr r12
+        addi r11,r11,lo16(L1$lz-L1$pb)
+        bctr
+.lazy_symbol_pointer
+L1$lz:
+        .indirect_symbol _invoke_count_words
+        .long dyld_stub_binding_helper
+
+
+.picsymbol_stub
+L_invoke_copy_to_stack$stub:
+        .indirect_symbol _invoke_copy_to_stack
+        mflr r0
+        bcl 20,31,L2$pb
+L2$pb:
+        mflr r11
+        addis r11,r11,ha16(L2$lz-L2$pb)
+        mtlr r0
+        lwz r12,lo16(L2$lz-L2$pb)(r11)
+        mtctr r12
+        addi r11,r11,lo16(L2$lz-L2$pb)
+        bctr
+.lazy_symbol_pointer
+L2$lz:
+        .indirect_symbol _invoke_copy_to_stack
+        .long dyld_stub_binding_helper
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparc64_openbsd.s b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparc64_openbsd.s
new file mode 100644
index 000000000..dfd6189f8
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparc64_openbsd.s
@@ -0,0 +1,86 @@
+/* -*- Mode: asm; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+    Platform specific code to invoke XPCOM methods on native objects
+    for sparcv9 Solaris.
+
+    See the SPARC Compliance Definition (SCD) Chapter 3
+    for more information about what is going on here, including
+    the use of BIAS (0x7ff).
+    The SCD is available from http://www.sparc.com/.
+*/
+
+        .global NS_InvokeByIndex
+        .type   NS_InvokeByIndex, #function
+
+/*
+    NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                     uint32_t paramCount, nsXPTCVariant* params);
+    
+*/
+NS_InvokeByIndex:
+        save    %sp,-(128 + 64),%sp ! room for the register window and
+                                    ! struct pointer, rounded up to 0 % 64
+        sll     %i2,4,%l0           ! assume the worst case
+                                    ! paramCount * 2 * 8 bytes
+        cmp     %l0, 0              ! are there any args? If not,
+        be      .invoke             ! no need to copy args to stack
+        nop
+
+        sub     %sp,%l0,%sp         ! create the additional stack space
+        add     %sp,0x7ff+136,%o0   ! step past the register window, the
+                                    ! struct result pointer and the 'this' slot
+        mov     %i2,%o1             ! paramCount
+        call    invoke_copy_to_stack
+        mov     %i3,%o2             ! params
+
+!
+!   load arguments from stack into the outgoing registers
+!   BIAS is 0x7ff (2047)
+!
+
+!   load the %o1..5 64bit (extended word) output registers registers 
+        ldx     [%sp + 0x7ff + 136],%o1    ! %i1
+        ldx     [%sp + 0x7ff + 144],%o2    ! %i2
+        ldx     [%sp + 0x7ff + 152],%o3    ! %i3
+        ldx     [%sp + 0x7ff + 160],%o4    ! %i4
+        ldx     [%sp + 0x7ff + 168],%o5    ! %i5
+
+!   load the even number double registers starting with %f2
+        ldd     [%sp + 0x7ff + 136],%f2
+        ldd     [%sp + 0x7ff + 144],%f4
+        ldd     [%sp + 0x7ff + 152],%f6
+        ldd     [%sp + 0x7ff + 160],%f8
+        ldd     [%sp + 0x7ff + 168],%f10
+        ldd     [%sp + 0x7ff + 176],%f12
+        ldd     [%sp + 0x7ff + 184],%f14
+        ldd     [%sp + 0x7ff + 192],%f16
+        ldd     [%sp + 0x7ff + 200],%f18
+        ldd     [%sp + 0x7ff + 208],%f20
+        ldd     [%sp + 0x7ff + 216],%f22
+        ldd     [%sp + 0x7ff + 224],%f24
+        ldd     [%sp + 0x7ff + 232],%f26
+        ldd     [%sp + 0x7ff + 240],%f28
+        ldd     [%sp + 0x7ff + 248],%f30
+
+!
+!   calculate the target address from the vtable
+!
+.invoke:
+        sll     %i1,3,%l0           ! index *= 8
+!       add     %l0,16,%l0          ! there are 2 extra entries in the vTable (16bytes)
+        ldx     [%i0],%l1           ! *that --> address of vtable
+        ldx     [%l0 + %l1],%l0     ! that->vtable[index * 8 + 16] --> address
+
+        jmpl    %l0,%o7             ! call the routine
+        mov     %i0,%o0             ! move 'this' pointer to out register
+
+        mov     %o0,%i0             ! propagate return value
+        ret
+        restore
+
+        .size    NS_InvokeByIndex, .-NS_InvokeByIndex
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparc_linux_GCC3.s b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparc_linux_GCC3.s
new file mode 100644
index 000000000..36196805e
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparc_linux_GCC3.s
@@ -0,0 +1,53 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Platform specific code to invoke XPCOM methods on native objects for
+ * Linux/Sparc with gcc 3 ABI.
+ */
+        .global NS_InvokeByIndex
+/*
+ *  NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+ *                 uint32_t paramCount, nsXPTCVariant* params);
+ *   
+ */
+NS_InvokeByIndex:
+        save    %sp,-(64 + 16),%sp   ! room for the register window and
+                                    ! struct pointer, rounded up to 0 % 16
+        mov     %i2,%o0             ! paramCount
+        call    invoke_count_words  ! returns the required stack size in %o0
+        mov     %i3,%o1             ! params
+        
+	sll     %o0,2,%l0           ! number of bytes
+        sub     %sp,%l0,%sp         ! create the additional stack space
+            
+        mov     %sp,%o0             ! pointer for copied args
+        add     %o0,72,%o0          ! step past the register window, the
+                                    ! struct result pointer and the 'this' slot
+        mov     %i2,%o1             ! paramCount
+        call    invoke_copy_to_stack
+        mov     %i3,%o2             ! params
+!
+!   calculate the target address from the vtable
+!
+	ld	[%i0],%l1	    ! *that --> vTable
+	sll	%i1,2,%i1	    ! multiply index by 4
+	add	%i1,%l1,%l1	    ! l1 now points to vTable entry
+        ld      [%l1],%l0           ! target address
+
+.L5:    ld      [%sp + 88],%o5
+.L4:	ld	[%sp + 84],%o4
+.L3:	ld	[%sp + 80],%o3
+.L2:	ld	[%sp + 76],%o2
+.L1:	ld	[%sp + 72],%o1
+.L0:
+        jmpl    %l0,%o7             ! call the routine
+! always have a 'this', from the incoming 'that'
+	mov	%i0,%o0
+        
+	mov     %o0,%i0             ! propagate return value
+        ret
+        restore
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparc_netbsd.s b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparc_netbsd.s
new file mode 100644
index 000000000..893432a5e
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparc_netbsd.s
@@ -0,0 +1,55 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+        .global XPTC_InvokeByIndex
+/*
+    XPTC_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                   uint32_t paramCount, nsXPTCVariant* params);
+    
+*/
+XPTC_InvokeByIndex:
+        save    %sp,-(64 + 16),%sp   ! room for the register window and
+                                    ! struct pointer, rounded up to 0 % 16
+        mov     %i2,%o0             ! paramCount
+        call    invoke_count_words  ! returns the required stack size in %o0
+        mov     %i3,%o1             ! params
+        
+	sll     %o0,2,%l0           ! number of bytes
+        sub     %sp,%l0,%sp         ! create the additional stack space
+            
+        mov     %sp,%o0             ! pointer for copied args
+        add     %o0,72,%o0          ! step past the register window, the
+                                    ! struct result pointer and the 'this' slot
+        mov     %i2,%o1             ! paramCount
+        call    invoke_copy_to_stack
+        mov     %i3,%o2             ! params
+!
+!   calculate the target address from the vtable
+!
+	add	%i1,1,%i1	    ! vTable is zero-based, index is 1 based (?)	
+	ld	[%i0],%l1	    ! *that --> vTable
+	sll	%i1,3,%i1
+	add	%i1,%l1,%l1	    ! vTable[index * 8], l1 now points to vTable entry
+	lduh	[%l1],%l0	    ! this adjustor
+	sll	%l0,16,%l0          ! sign extend to 32 bits
+	sra     %l0,16,%l0
+	add     %l0,%i0,%i0         ! adjust this
+        ld      [%l1 + 4],%l0       ! target address
+
+.L5:    ld      [%sp + 88],%o5
+.L4:	ld	[%sp + 84],%o4
+.L3:	ld	[%sp + 80],%o3
+.L2:	ld	[%sp + 76],%o2
+.L1:	ld	[%sp + 72],%o1
+.L0:
+        jmpl    %l0,%o7             ! call the routine
+! always have a 'this', from the incoming 'that'
+	mov	%i0,%o0
+        
+	mov     %o0,%i0             ! propagate return value
+        ret
+        restore
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparc_openbsd.s b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparc_openbsd.s
new file mode 100644
index 000000000..1ef695370
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparc_openbsd.s
@@ -0,0 +1,55 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+        .global XPTC_InvokeByIndex
+/*
+    XPTC_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                   uint32_t paramCount, nsXPTCVariant* params);
+    
+*/
+XPTC_InvokeByIndex:
+        save    %sp,-(64 + 16),%sp  ! room for the register window and
+                                    ! struct pointer, rounded up to 0 % 16
+        mov     %i2,%o0             ! paramCount
+        call    invoke_count_words  ! returns the required stack size in %o0
+        mov     %i3,%o1             ! params
+        
+	sll     %o0,2,%l0           ! number of bytes
+        sub     %sp,%l0,%sp         ! create the additional stack space
+            
+        mov     %sp,%o0             ! pointer for copied args
+        add     %o0,72,%o0          ! step past the register window, the
+                                    ! struct result pointer and the 'this' slot
+        mov     %i2,%o1             ! paramCount
+        call    invoke_copy_to_stack
+        mov     %i3,%o2             ! params
+!
+!   calculate the target address from the vtable
+!
+	add	%i1,1,%i1	    ! vTable is zero-based, index is 1 based (?)	
+	ld	[%i0],%l1	    ! *that --> vTable
+	sll	%i1,3,%i1
+	add	%i1,%l1,%l1	    ! vTable[index * 8], l1 now points to vTable entry
+	lduh	[%l1],%l0	    ! this adjustor
+	sll	%l0,16,%l0          ! sign extend to 32 bits
+	sra     %l0,16,%l0
+	add     %l0,%i0,%i0         ! adjust this
+	ld      [%l1 + 4],%l0       ! target address
+
+.L5:    ld      [%sp + 88],%o5
+.L4:	ld	[%sp + 84],%o4
+.L3:	ld	[%sp + 80],%o3
+.L2:	ld	[%sp + 76],%o2
+.L1:	ld	[%sp + 72],%o1
+.L0:
+        jmpl    %l0,%o7             ! call the routine
+! always have a 'this', from the incoming 'that'
+	mov	%i0,%o0
+        
+	mov     %o0,%i0             ! propagate return value
+        ret
+        restore
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparc_solaris_GCC3.s b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparc_solaris_GCC3.s
new file mode 100644
index 000000000..54adcd147
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparc_solaris_GCC3.s
@@ -0,0 +1,52 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Platform specific code to invoke XPCOM methods on native objects for
+ * solaris/sparc with gcc 3 ABI.
+ */
+        .global NS_InvokeByIndex
+/*
+ *  NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+ *                   uint32_t paramCount, nsXPTCVariant* params);
+ */
+NS_InvokeByIndex:
+        save    %sp,-(64 + 32),%sp  ! room for the register window and
+                                    ! struct pointer, rounded up to 0 % 32
+        mov     %i2,%o0             ! paramCount
+        call    invoke_count_words  ! returns the required stack size in %o0
+        mov     %i3,%o1             ! params
+        
+        sll     %o0,2,%l0           ! number of bytes
+        sub     %sp,%l0,%sp         ! create the additional stack space
+            
+        mov     %sp,%o0             ! pointer for copied args
+        add     %o0,72,%o0          ! step past the register window, the
+                                    ! struct result pointer and the 'this' slot
+        mov     %i2,%o1             ! paramCount
+        call    invoke_copy_to_stack
+        mov     %i3,%o2             ! params
+!
+!   calculate the target address from the vtable
+!
+        ld      [%i0],%l1           ! *that --> vTable
+        sll     %i1,2,%i1           ! multiply index by 4
+        add     %i1,%l1,%l1         ! l1 now points to vTable entry
+        ld      [%l1],%l0           ! target address
+
+.L5:    ld      [%sp + 88],%o5
+.L4:    ld      [%sp + 84],%o4
+.L3:    ld      [%sp + 80],%o3
+.L2:    ld      [%sp + 76],%o2
+.L1:    ld      [%sp + 72],%o1
+.L0:
+        jmpl    %l0,%o7             ! call the routine
+! always have a 'this', from the incoming 'that'
+        mov     %i0,%o0
+        
+        mov     %o0,%i0             ! propagate return value
+        ret
+        restore
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparc_solaris_SUNW.s b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparc_solaris_SUNW.s
new file mode 100644
index 000000000..013770392
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparc_solaris_SUNW.s
@@ -0,0 +1,56 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+        .global NS_InvokeByIndex
+        .type   NS_InvokeByIndex, #function
+/*
+    NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                     uint32_t paramCount, nsXPTCVariant* params);
+    
+*/
+NS_InvokeByIndex:
+        save    %sp,-(64 + 32),%sp  ! room for the register window and
+                                    ! struct pointer, rounded up to 0 % 32
+        sll     %i2,3,%l0           ! assume the worst case
+                                    ! paramCount * 2 * 4 bytes
+        cmp     %l0, 0              ! are there any args? If not,
+        be      .invoke             ! no need to copy args to stack
+
+        sub     %sp,%l0,%sp         ! create the additional stack space
+        add     %sp,72,%o0          ! step past the register window, the
+                                    ! struct result pointer and the 'this' slot
+        mov     %i2,%o1             ! paramCount
+        call    invoke_copy_to_stack
+        mov     %i3,%o2             ! params
+
+!
+!   load arguments from stack into the outgoing registers
+!
+        ld      [%sp + 72],%o1
+        ld      [%sp + 76],%o2
+        ld      [%sp + 80],%o3
+        ld      [%sp + 84],%o4
+        ld      [%sp + 88],%o5
+
+!
+!   calculate the target address from the vtable
+!
+.invoke:
+        sll     %i1,2,%l0           ! index *= 4
+        add     %l0,8,%l0           ! there are 2 extra entries in the vTable
+        ld      [%i0],%l1           ! *that --> address of vtable
+        ld      [%l0 + %l1],%l0     ! that->vtable[index * 4 + 8] --> address
+
+        jmpl    %l0,%o7             ! call the routine
+        mov     %i0,%o0             ! move 'this' pointer to out register
+
+        mov     %o0,%i0             ! propagate return value
+        ret
+        restore
+
+        .size    NS_InvokeByIndex, .-NS_InvokeByIndex
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparcv9_solaris_SUNW.s b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparcv9_solaris_SUNW.s
new file mode 100644
index 000000000..34861abc0
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_sparcv9_solaris_SUNW.s
@@ -0,0 +1,85 @@
+/* -*- Mode: asm; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+    Platform specific code to invoke XPCOM methods on native objects
+    for sparcv9 Solaris.
+
+    See the SPARC Compliance Definition (SCD) Chapter 3
+    for more information about what is going on here, including
+    the use of BIAS (0x7ff).
+    The SCD is available from http://www.sparc.com/.
+*/
+
+        .global NS_InvokeByIndex
+        .type   NS_InvokeByIndex, #function
+
+/*
+    NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                     uint32_t paramCount, nsXPTCVariant* params);
+    
+*/
+NS_InvokeByIndex:
+        save    %sp,-(128 + 64),%sp ! room for the register window and
+                                    ! struct pointer, rounded up to 0 % 64
+        sll     %i2,4,%l0           ! assume the worst case
+                                    ! paramCount * 2 * 8 bytes
+        cmp     %l0, 0              ! are there any args? If not,
+        be      .invoke             ! no need to copy args to stack
+
+        sub     %sp,%l0,%sp         ! create the additional stack space
+        add     %sp,0x7ff+136,%o0   ! step past the register window, the
+                                    ! struct result pointer and the 'this' slot
+        mov     %i2,%o1             ! paramCount
+        call    invoke_copy_to_stack
+        mov     %i3,%o2             ! params
+
+!
+!   load arguments from stack into the outgoing registers
+!   BIAS is 0x7ff (2047)
+!
+
+!   load the %o1..5 64bit (extended word) output registers registers 
+        ldx     [%sp + 0x7ff + 136],%o1    ! %i1
+        ldx     [%sp + 0x7ff + 144],%o2    ! %i2
+        ldx     [%sp + 0x7ff + 152],%o3    ! %i3
+        ldx     [%sp + 0x7ff + 160],%o4    ! %i4
+        ldx     [%sp + 0x7ff + 168],%o5    ! %i5
+
+!   load the even number double registers starting with %d2
+        ldd     [%sp + 0x7ff + 136],%d2
+        ldd     [%sp + 0x7ff + 144],%d4
+        ldd     [%sp + 0x7ff + 152],%d6
+        ldd     [%sp + 0x7ff + 160],%d8
+        ldd     [%sp + 0x7ff + 168],%d10
+        ldd     [%sp + 0x7ff + 176],%d12
+        ldd     [%sp + 0x7ff + 184],%d14
+        ldd     [%sp + 0x7ff + 192],%d16
+        ldd     [%sp + 0x7ff + 200],%d18
+        ldd     [%sp + 0x7ff + 208],%d20
+        ldd     [%sp + 0x7ff + 216],%d22
+        ldd     [%sp + 0x7ff + 224],%d24
+        ldd     [%sp + 0x7ff + 232],%d26
+        ldd     [%sp + 0x7ff + 240],%d28
+        ldd     [%sp + 0x7ff + 248],%d30
+
+!
+!   calculate the target address from the vtable
+!
+.invoke:
+        sll     %i1,3,%l0           ! index *= 8
+        add     %l0,16,%l0          ! there are 2 extra entries in the vTable (16bytes)
+        ldx     [%i0],%l1           ! *that --> address of vtable
+        ldx     [%l0 + %l1],%l0     ! that->vtable[index * 8 + 16] --> address
+
+        jmpl    %l0,%o7             ! call the routine
+        mov     %i0,%o0             ! move 'this' pointer to out register
+
+        mov     %o0,%i0             ! propagate return value
+        ret
+        restore
+
+        .size    NS_InvokeByIndex, .-NS_InvokeByIndex
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_x86_solaris_SUNW.s b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_x86_solaris_SUNW.s
new file mode 100644
index 000000000..af665a162
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_asm_x86_solaris_SUNW.s
@@ -0,0 +1,55 @@
+	.globl NS_InvokeByIndex
+	.type NS_InvokeByIndex, @function
+NS_InvokeByIndex:
+	push       %ebp
+	movl       %esp,%ebp
+	push       %ebx
+	call       .CG0.66
+.CG0.66:
+	pop        %ebx
+	addl       $_GLOBAL_OFFSET_TABLE_+0x1,%ebx
+	push       20(%ebp)
+	push       16(%ebp)
+	push       12(%ebp)
+	push       8(%ebp)
+	/ INLINE: invoke_by_index
+
+
+
+	pushl	%ebx
+	pushl	%esi
+	movl	%esp, %ebx
+
+	pushl	0x14(%ebp)
+	pushl	0x10(%ebp)
+	call	invoke_count_words
+	mov	%ebx, %esp
+
+	sall	$0x2 , %eax
+	subl	%eax, %esp
+	movl	%esp, %esi
+
+	pushl	%esp
+	pushl	0x14(%ebp)
+	pushl	0x10(%ebp)
+	call	invoke_copy_to_stack
+	movl	%esi, %esp
+
+	movl	0x8(%ebp), %ecx
+	pushl	%ecx
+	movl	(%ecx), %edx
+	movl	0xc(%ebp), %eax
+	movl	0x8(%edx, %eax, 4), %edx
+
+	call	*%edx
+	mov	%ebx, %esp
+	popl	%esi
+	popl	%ebx
+	/ INLINE_END
+	addl       $16,%esp
+	pop        %ebx
+	movl       %ebp,%esp
+	pop        %ebp
+	ret        
+	.size NS_InvokeByIndex, . - NS_InvokeByIndex
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_darwin.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_darwin.cpp
new file mode 100644
index 000000000..04407db39
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_darwin.cpp
@@ -0,0 +1,16 @@
+/* -*- Mode: C -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#if defined(__i386__)
+#include "xptcinvoke_gcc_x86_unix.cpp"
+#elif defined(__x86_64__)
+#include "xptcinvoke_x86_64_unix.cpp"
+#elif defined(__ppc__)
+#include "xptcinvoke_ppc_rhapsody.cpp"
+#elif defined(__arm__)
+#include "xptcinvoke_arm.cpp"
+#else
+#error unknown cpu architecture
+#endif
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_gcc_x86_unix.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_gcc_x86_unix.cpp
new file mode 100644
index 000000000..d4a8a12fb
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_gcc_x86_unix.cpp
@@ -0,0 +1,97 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+#include "xptc_gcc_x86_unix.h"
+
+extern "C" {
+static void ATTRIBUTE_USED __attribute__ ((regparm(3)))
+invoke_copy_to_stack(uint32_t paramCount, nsXPTCVariant* s, uint32_t* d)
+{
+    for(uint32_t i = paramCount; i >0; i--, d++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            *((void**)d) = s->ptr;
+            continue;
+        }
+
+        switch(s->type)
+        {
+        case nsXPTType::T_I64    : *((int64_t*) d) = s->val.i64; d++;    break;
+        case nsXPTType::T_U64    : *((uint64_t*)d) = s->val.u64; d++;    break;
+        case nsXPTType::T_DOUBLE : *((double*)  d) = s->val.d;   d++;    break;
+        default                  : *((void**)d)    = s->val.p;           break;
+        }
+    }
+}
+} // extern "C"
+
+/*
+  EXPORT_XPCOM_API(nsresult)
+  NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                   uint32_t paramCount, nsXPTCVariant* params);
+
+  Each param takes at most two 4-byte words.
+  It doesn't matter if we push too many words, and calculating the exact
+  amount takes time.
+
+  that        = ebp + 0x08
+  methodIndex = ebp + 0x0c
+  paramCount  = ebp + 0x10
+  params      = ebp + 0x14
+
+*/
+
+__asm__ (
+	".text\n\t"
+/* alignment here seems unimportant here; this was 16, now it's 2 which
+   is what xptcstubs uses. */
+	".align 2\n\t"
+	".globl " SYMBOL_UNDERSCORE "NS_InvokeByIndex\n\t"
+#ifndef XP_MACOSX
+	".type  " SYMBOL_UNDERSCORE "NS_InvokeByIndex,@function\n"
+#endif
+	SYMBOL_UNDERSCORE "NS_InvokeByIndex:\n\t"
+	"pushl %ebp\n\t"
+	"movl  %esp, %ebp\n\t"
+	"movl  0x10(%ebp), %eax\n\t"
+	"leal  0(,%eax,8),%edx\n\t"
+
+        /* set up call frame for method. */
+	"subl  %edx, %esp\n\t"       /* make room for params. */
+/* Align to maximum x86 data size: 128 bits == 16 bytes == XMM register size.
+ * This is to avoid protection faults where SSE+ alignment of stack pointer
+ * is assumed and required, e.g. by GCC4's -ftree-vectorize option.
+ */
+	"andl  $0xfffffff0, %esp\n\t"   /* drop(?) stack ptr to 128-bit align */
+/* $esp should be aligned to a 16-byte boundary here (note we include an 
+ * additional 4 bytes in a later push instruction). This will ensure $ebp 
+ * in the function called below is aligned to a 0x8 boundary. SSE instructions 
+ * like movapd/movdqa expect memory operand to be aligned on a 16-byte
+ * boundary. The GCC compiler will generate the memory operand using $ebp
+ * with an 8-byte offset.
+ */
+	"subl  $0xc, %esp\n\t"          /* lower again; push/call below will re-align */
+	"movl  %esp, %ecx\n\t"          /* ecx = d */
+	"movl  8(%ebp), %edx\n\t"       /* edx = this */
+	"pushl %edx\n\t"                /* push this. esp % 16 == 0 */
+
+	"movl  0x14(%ebp), %edx\n\t"
+	"call  " SYMBOL_UNDERSCORE "invoke_copy_to_stack\n\t"
+	"movl  0x08(%ebp), %ecx\n\t"	/* 'that' */
+	"movl  (%ecx), %edx\n\t"
+	"movl  0x0c(%ebp), %eax\n\t"    /* function index */
+	"leal  (%edx,%eax,4), %edx\n\t"
+	"call  *(%edx)\n\t"
+	"movl  %ebp, %esp\n\t"
+	"popl  %ebp\n\t"
+	"ret\n"
+#ifndef XP_MACOSX
+	".size " SYMBOL_UNDERSCORE "NS_InvokeByIndex, . -" SYMBOL_UNDERSCORE "NS_InvokeByIndex\n\t"
+#endif
+);
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_ipf32.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_ipf32.cpp
new file mode 100644
index 000000000..1500f3175
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_ipf32.cpp
@@ -0,0 +1,132 @@
+
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "xptcprivate.h"
+
+#include <iostream.h>
+
+// "This code is for IA64 only"
+
+
+/* invoke_copy_to_stack() will copy from variant array 's' to
+ * the stack argument area 'mloc', the integer register area 'iloc', and
+ * the float register area 'floc'.
+ *
+ */
+extern "C" void
+invoke_copy_to_stack(uint64_t* mloc, uint64_t* iloc, uint64_t* floc,
+  const uint32_t paramCount, nsXPTCVariant* s)
+{
+  uint64_t* dest = mloc;
+  uint32_t len = paramCount;
+  nsXPTCVariant* source = s;
+
+  uint32_t indx;
+  uint32_t endlen;
+  endlen = (len > 7) ? 7 : len;
+  /* handle the memory arguments */
+  for (indx = 7; indx < len; ++indx)
+  {
+    if (source[indx].IsPtrData())
+    {
+#ifdef __LP64__
+      /* 64 bit pointer mode */
+      *((void**) dest) = source[indx].ptr;
+#else
+      /* 32 bit pointer mode */
+      uint32_t* adr = (uint32_t*) dest;
+      *(adr) = 0;
+      *(adr+1) = (uint32_t) source[indx].ptr;
+#endif
+    }
+    else
+    switch (source[indx].type)
+    {
+    case nsXPTType::T_I8    : *(dest) = source[indx].val.i8;  break;
+    case nsXPTType::T_I16   : *(dest) = source[indx].val.i16; break;
+    case nsXPTType::T_I32   : *(dest) = source[indx].val.i32; break;
+    case nsXPTType::T_I64   : *(dest) = source[indx].val.i64; break;
+    case nsXPTType::T_U8    : *(dest) = source[indx].val.u8;  break;
+    case nsXPTType::T_U16   : *(dest) = source[indx].val.u16; break;
+    case nsXPTType::T_U32   : *(dest) = source[indx].val.u32; break;
+    case nsXPTType::T_U64   : *(dest) = source[indx].val.u64; break;
+    case nsXPTType::T_FLOAT : *(dest) = source[indx].val.u32; break;
+    case nsXPTType::T_DOUBLE: *(dest) = source[indx].val.u64; break;
+    case nsXPTType::T_BOOL  : *(dest) = source[indx].val.b; break;
+    case nsXPTType::T_CHAR  : *(dest) = source[indx].val.c; break;
+    case nsXPTType::T_WCHAR : *(dest) = source[indx].val.wc; break;
+    default:
+    // all the others are plain pointer types
+#ifdef __LP64__
+      /* 64 bit pointer mode */
+      *((void**) dest) = source[indx].val.p;
+#else
+      {
+      /* 32 bit pointer mode */
+      uint32_t* adr = (uint32_t*) dest;
+      *(adr) = 0;
+      *(adr+1) = (uint32_t) source[indx].val.p;
+      }
+#endif
+    }
+    ++dest;
+  }
+  /* process register arguments */
+  dest = iloc;
+  for (indx = 0; indx < endlen; ++indx)
+  {
+    if (source[indx].IsPtrData())
+    {
+#ifdef __LP64__
+      /* 64 bit pointer mode */
+      *((void**) dest) = source[indx].ptr;
+#else
+      /* 32 bit pointer mode */
+      uint32_t* adr = (uint32_t*) dest;
+      *(adr) = 0;
+      *(adr+1) = (uint32_t) source[indx].ptr;
+#endif
+    }
+    else
+    switch (source[indx].type)
+    {
+    case nsXPTType::T_I8    : *(dest) = source[indx].val.i8; break;
+    case nsXPTType::T_I16   : *(dest) = source[indx].val.i16; break;
+    case nsXPTType::T_I32   : *(dest) = source[indx].val.i32; break;
+    case nsXPTType::T_I64   : *(dest) = source[indx].val.i64; break;
+    case nsXPTType::T_U8    : *(dest) = source[indx].val.u8; break;
+    case nsXPTType::T_U16   : *(dest) = source[indx].val.u16; break;
+    case nsXPTType::T_U32   : *(dest) = source[indx].val.u32; break;
+    case nsXPTType::T_U64   : *(dest) = source[indx].val.u64; break;
+    case nsXPTType::T_FLOAT :
+      *((double*) (floc++)) = (double) source[indx].val.f;
+      break;
+    case nsXPTType::T_DOUBLE:
+      *((double*) (floc++)) = source[indx].val.d;
+      break;
+    case nsXPTType::T_BOOL  : *(dest) = source[indx].val.b; break;
+    case nsXPTType::T_CHAR  : *(dest) = source[indx].val.c; break;
+    case nsXPTType::T_WCHAR : *(dest) = source[indx].val.wc; break;
+    default:
+    // all the others are plain pointer types
+#ifdef __LP64__
+      /* 64 bit pointer mode */
+      *((void**) dest) = source[indx].val.p;
+#else
+      {
+      /* 32 bit pointer mode */
+      uint32_t* adr = (uint32_t*) dest;
+      *(adr) = 0;
+      *(adr+1) = (uint32_t) source[indx].val.p;
+      }
+#endif
+    }
+    ++dest;
+  }
+
+}
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_ipf64.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_ipf64.cpp
new file mode 100644
index 000000000..c2a4dd088
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_ipf64.cpp
@@ -0,0 +1,100 @@
+
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "xptcprivate.h"
+
+#include <stdint.h>
+
+// "This code is for IA64 only"
+
+
+/* invoke_copy_to_stack() will copy from variant array 's' to
+ * the stack argument area 'mloc', the integer register area 'iloc', and
+ * the float register area 'floc'.
+ *
+ */
+extern "C" void
+invoke_copy_to_stack(uint64_t* mloc, uint64_t* iloc, uint64_t* floc,
+  const uint32_t paramCount, nsXPTCVariant* s)
+{
+  uint64_t* dest = mloc;
+  uint32_t len = paramCount;
+  nsXPTCVariant* source = s;
+
+  uint32_t indx;
+  uint32_t endlen;
+  endlen = (len > 7) ? 7 : len;
+  /* handle the memory arguments */
+  for (indx = 7; indx < len; ++indx)
+  {
+    if (source[indx].IsPtrData())
+    {
+      /* 64 bit pointer mode */
+      *((void**) dest) = source[indx].ptr;
+    }
+    else
+    switch (source[indx].type)
+    {
+    case nsXPTType::T_I8    : *(dest) = source[indx].val.i8;  break;
+    case nsXPTType::T_I16   : *(dest) = source[indx].val.i16; break;
+    case nsXPTType::T_I32   : *(dest) = source[indx].val.i32; break;
+    case nsXPTType::T_I64   : *(dest) = source[indx].val.i64; break;
+    case nsXPTType::T_U8    : *(dest) = source[indx].val.u8;  break;
+    case nsXPTType::T_U16   : *(dest) = source[indx].val.u16; break;
+    case nsXPTType::T_U32   : *(dest) = source[indx].val.u32; break;
+    case nsXPTType::T_U64   : *(dest) = source[indx].val.u64; break;
+    case nsXPTType::T_FLOAT : *(dest) = source[indx].val.u32; break;
+    case nsXPTType::T_DOUBLE: *(dest) = source[indx].val.u64; break;
+    case nsXPTType::T_BOOL  : *(dest) = source[indx].val.b; break;
+    case nsXPTType::T_CHAR  : *(dest) = source[indx].val.c; break;
+    case nsXPTType::T_WCHAR : *(dest) = source[indx].val.wc; break;
+    default:
+    // all the others are plain pointer types
+      /* 64 bit pointer mode */
+      *((void**) dest) = source[indx].val.p;
+    }
+    ++dest;
+  }
+  /* process register arguments */
+  dest = iloc;
+  for (indx = 0; indx < endlen; ++indx)
+  {
+    if (source[indx].IsPtrData())
+    {
+      /* 64 bit pointer mode */
+      *((void**) dest) = source[indx].ptr;
+    }
+    else
+    switch (source[indx].type)
+    {
+    case nsXPTType::T_I8    : *(dest) = source[indx].val.i8; break;
+    case nsXPTType::T_I16   : *(dest) = source[indx].val.i16; break;
+    case nsXPTType::T_I32   : *(dest) = source[indx].val.i32; break;
+    case nsXPTType::T_I64   : *(dest) = source[indx].val.i64; break;
+    case nsXPTType::T_U8    : *(dest) = source[indx].val.u8; break;
+    case nsXPTType::T_U16   : *(dest) = source[indx].val.u16; break;
+    case nsXPTType::T_U32   : *(dest) = source[indx].val.u32; break;
+    case nsXPTType::T_U64   : *(dest) = source[indx].val.u64; break;
+    case nsXPTType::T_FLOAT :
+      *((double*) (floc++)) = (double) source[indx].val.f;
+      break;
+    case nsXPTType::T_DOUBLE:
+      *((double*) (floc++)) = source[indx].val.d;
+      break;
+    case nsXPTType::T_BOOL  : *(dest) = source[indx].val.b; break;
+    case nsXPTType::T_CHAR  : *(dest) = source[indx].val.c; break;
+    case nsXPTType::T_WCHAR : *(dest) = source[indx].val.wc; break;
+    default:
+    // all the others are plain pointer types
+      /* 64 bit pointer mode */
+      *((void**) dest) = source[indx].val.p;
+    }
+    ++dest;
+  }
+
+}
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_linux_alpha.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_linux_alpha.cpp
new file mode 100644
index 000000000..dc111e435
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_linux_alpha.cpp
@@ -0,0 +1,144 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+/* Prototype specifies unmangled function name and disables unused warning */
+static void
+invoke_copy_to_stack(uint64_t* d, uint32_t paramCount, nsXPTCVariant* s)
+__asm__("invoke_copy_to_stack") __attribute__((used));
+
+static void
+invoke_copy_to_stack(uint64_t* d, uint32_t paramCount, nsXPTCVariant* s)
+{
+    const uint8_t NUM_ARG_REGS = 6-1;        // -1 for "this" pointer
+
+    for(uint32_t i = 0; i < paramCount; i++, d++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            *d = (uint64_t)s->ptr;
+            continue;
+        }
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     : *d = (uint64_t)s->val.i8;     break;
+        case nsXPTType::T_I16    : *d = (uint64_t)s->val.i16;    break;
+        case nsXPTType::T_I32    : *d = (uint64_t)s->val.i32;    break;
+        case nsXPTType::T_I64    : *d = (uint64_t)s->val.i64;    break;
+        case nsXPTType::T_U8     : *d = (uint64_t)s->val.u8;     break;
+        case nsXPTType::T_U16    : *d = (uint64_t)s->val.u16;    break;
+        case nsXPTType::T_U32    : *d = (uint64_t)s->val.u32;    break;
+        case nsXPTType::T_U64    : *d = (uint64_t)s->val.u64;    break;
+        case nsXPTType::T_FLOAT  :
+            if(i < NUM_ARG_REGS)
+            {
+                // convert floats to doubles if they are to be passed
+                // via registers so we can just deal with doubles later
+                union { uint64_t u64; double d; } t;
+                t.d = (double)s->val.f;
+                *d = t.u64;
+            }
+            else
+                // otherwise copy to stack normally
+                *d = (uint64_t)s->val.u32;
+            break;
+        case nsXPTType::T_DOUBLE : *d = (uint64_t)s->val.u64;    break;
+        case nsXPTType::T_BOOL   : *d = (uint64_t)s->val.b;      break;
+        case nsXPTType::T_CHAR   : *d = (uint64_t)s->val.c;      break;
+        case nsXPTType::T_WCHAR  : *d = (uint64_t)s->val.wc;     break;
+        default:
+            // all the others are plain pointer types
+            *d = (uint64_t)s->val.p;
+            break;
+        }
+    }
+}
+
+/*
+ * EXPORT_XPCOM_API(nsresult)
+ * NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+ *                  uint32_t paramCount, nsXPTCVariant* params)
+ */
+__asm__(
+    "#### NS_InvokeByIndex ####\n"
+".text\n\t"
+    ".align 5\n\t"
+    ".globl NS_InvokeByIndex\n\t"
+    ".ent NS_InvokeByIndex\n"
+"NS_InvokeByIndex:\n\t"
+    ".frame $15,32,$26,0\n\t"
+    ".mask 0x4008000,-32\n\t"
+    "ldgp $29,0($27)\n"
+"$NS_InvokeByIndex..ng:\n\t"
+    "subq $30,32,$30\n\t"
+    "stq $26,0($30)\n\t"
+    "stq $15,8($30)\n\t"
+    "bis $30,$30,$15\n\t"
+    ".prologue 1\n\t"
+
+    /*
+     * Allocate enough stack space to hold the greater of 6 or "paramCount"+1
+     * parameters. (+1 for "this" pointer)  Room for at least 6 parameters
+     * is required for storage of those passed via registers.
+     */
+
+    "bis $31,5,$2\n\t"      /* count = MAX(5, "paramCount") */
+    "cmplt $2,$18,$1\n\t"
+    "cmovne $1,$18,$2\n\t"
+    "s8addq $2,16,$1\n\t"   /* room for count+1 params (8 bytes each) */
+    "bic $1,15,$1\n\t"      /* stack space is rounded up to 0 % 16 */
+    "subq $30,$1,$30\n\t"
+
+    "stq $16,0($30)\n\t"    /* save "that" (as "this" pointer) */
+    "stq $17,16($15)\n\t"   /* save "methodIndex" */
+
+    "addq $30,8,$16\n\t"    /* pass stack pointer */
+    "bis $18,$18,$17\n\t"   /* pass "paramCount" */
+    "bis $19,$19,$18\n\t"   /* pass "params" */
+    "bsr $26,$invoke_copy_to_stack..ng\n\t"     /* call invoke_copy_to_stack */
+
+    /*
+     * Copy the first 6 parameters to registers and remove from stack frame.
+     * Both the integer and floating point registers are set for each parameter
+     * except the first which is the "this" pointer.  (integer only)
+     * The floating point registers are all set as doubles since the
+     * invoke_copy_to_stack function should have converted the floats.
+     */
+    "ldq $16,0($30)\n\t"    /* integer registers */
+    "ldq $17,8($30)\n\t"
+    "ldq $18,16($30)\n\t"
+    "ldq $19,24($30)\n\t"
+    "ldq $20,32($30)\n\t"
+    "ldq $21,40($30)\n\t"
+    "ldt $f17,8($30)\n\t"   /* floating point registers */
+    "ldt $f18,16($30)\n\t"
+    "ldt $f19,24($30)\n\t"
+    "ldt $f20,32($30)\n\t"
+    "ldt $f21,40($30)\n\t"
+
+    "addq $30,48,$30\n\t"   /* remove params from stack */
+
+    /*
+     * Call the virtual function with the constructed stack frame.
+     */
+    "bis $16,$16,$1\n\t"    /* load "this" */
+    "ldq $2,16($15)\n\t"    /* load "methodIndex" */
+    "ldq $1,0($1)\n\t"      /* load vtable */
+    "s8addq $2,$31,$2\n\t"  /* vtable index = "methodIndex" * 8 */
+    "addq $1,$2,$1\n\t"
+    "ldq $27,0($1)\n\t"     /* load address of function */
+    "jsr $26,($27),0\n\t"   /* call virtual function */
+    "ldgp $29,0($26)\n\t"
+
+    "bis $15,$15,$30\n\t"
+    "ldq $26,0($30)\n\t"
+    "ldq $15,8($30)\n\t"
+    "addq $30,32,$30\n\t"
+    "ret $31,($26),1\n\t"
+    ".end NS_InvokeByIndex"
+    );
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_linux_m68k.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_linux_m68k.cpp
new file mode 100644
index 000000000..6f2934cbc
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_linux_m68k.cpp
@@ -0,0 +1,130 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+// Remember that these 'words' are 32bit DWORDS
+
+extern "C" {
+    static uint32_t
+    invoke_count_words(uint32_t paramCount, nsXPTCVariant* s)
+    {
+        uint32_t result = 0;
+        for(uint32_t i = 0; i < paramCount; i++, s++)
+        {
+            if(s->IsPtrData())
+            {
+                result++;
+                continue;
+            }
+            switch(s->type)
+            {
+            case nsXPTType::T_I8     :
+            case nsXPTType::T_I16    :
+            case nsXPTType::T_I32    :
+                result++;
+                break;
+            case nsXPTType::T_I64    :
+                result+=2;
+                break;
+            case nsXPTType::T_U8     :
+            case nsXPTType::T_U16    :
+            case nsXPTType::T_U32    :
+                result++;
+                break;
+            case nsXPTType::T_U64    :
+                result+=2;
+                break;
+            case nsXPTType::T_FLOAT  :
+                result++;
+                break;
+            case nsXPTType::T_DOUBLE :
+                result+=2;
+                break;
+            case nsXPTType::T_BOOL   :
+            case nsXPTType::T_CHAR   :
+            case nsXPTType::T_WCHAR  :
+                result++;
+                break;
+            default:
+                // all the others are plain pointer types
+                result++;
+                break;
+            }
+        }
+        return result;
+    }
+
+    void
+    invoke_copy_to_stack(uint32_t* d, uint32_t paramCount, nsXPTCVariant* s)
+    {
+        for(uint32_t i = 0; i < paramCount; i++, d++, s++)
+        {
+            if(s->IsPtrData())
+            {
+                *((void**)d) = s->ptr;
+                continue;
+            }
+            switch(s->type)
+            {
+            // 8 and 16 bit types should be promoted to 32 bits when copying
+            // onto the stack.
+            case nsXPTType::T_I8     : *((uint32_t*)d) = s->val.i8;          break;
+            case nsXPTType::T_I16    : *((uint32_t*)d) = s->val.i16;         break;
+            case nsXPTType::T_I32    : *((int32_t*) d) = s->val.i32;         break;
+            case nsXPTType::T_I64    : *((int64_t*) d) = s->val.i64; d++;    break;
+            case nsXPTType::T_U8     : *((uint32_t*)d) = s->val.u8;          break;
+            case nsXPTType::T_U16    : *((uint32_t*)d) = s->val.u16;         break;
+            case nsXPTType::T_U32    : *((uint32_t*)d) = s->val.u32;         break;
+            case nsXPTType::T_U64    : *((uint64_t*)d) = s->val.u64; d++;    break;
+            case nsXPTType::T_FLOAT  : *((float*)   d) = s->val.f;           break;
+            case nsXPTType::T_DOUBLE : *((double*)  d) = s->val.d;   d++;    break;
+            case nsXPTType::T_BOOL   : *((uint32_t*)d) = s->val.b;           break;
+            case nsXPTType::T_CHAR   : *((uint32_t*)d) = s->val.c;           break;
+            case nsXPTType::T_WCHAR  : *((wchar_t*) d) = s->val.wc;          break;
+
+            default:
+                // all the others are plain pointer types
+                *((void**)d) = s->val.p;
+                break;
+            }
+        }
+    }
+}
+
+EXPORT_XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                   uint32_t paramCount, nsXPTCVariant* params)
+{
+    uint32_t result, n;
+
+    n = invoke_count_words(paramCount, params) * 4;
+
+ __asm__ __volatile__(
+    "subl  %5, %%sp\n\t"      /* make room for params */
+    "movel %4, %%sp@-\n\t"
+    "movel %3, %%sp@-\n\t"
+    "pea   %%sp@(8)\n\t"
+    "jbsr  invoke_copy_to_stack\n\t"   /* copy params */
+    "addw  #12, %%sp\n\t"
+    "movel %1, %%sp@-\n\t"
+    "movel %1@, %%a0\n\t"
+    "movel %%a0@(%2:l:4), %%a0\n\t"
+    "jbsr  %%a0@\n\t"         /* safe to not cleanup sp */
+    "lea   %%sp@(4,%5:l), %%sp\n\t"
+    "movel %%d0, %0"
+    : "=d" (result)         /* %0 */
+    : "a" (that),           /* %1 */
+      "d" (methodIndex),    /* %2 */
+      "g" (paramCount),     /* %3 */
+      "g" (params),         /* %4 */
+      "d" (n)               /* %5 */
+    : "a0", "a1", "d0", "d1", "memory"
+    );
+  
+  return result;
+}
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_linux_s390.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_linux_s390.cpp
new file mode 100644
index 000000000..573dfb00c
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_linux_s390.cpp
@@ -0,0 +1,195 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+
+static uint32_t
+invoke_count_words(uint32_t paramCount, nsXPTCVariant* s)
+{
+    uint32_t overflow = 0, gpr = 1 /*this*/, fpr = 0;
+    for(uint32_t i = 0; i < paramCount; i++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            if (gpr < 5) gpr++; else overflow++;
+            continue;
+        }
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     :
+        case nsXPTType::T_I16    :
+        case nsXPTType::T_I32    :
+            if (gpr < 5) gpr++; else overflow++;
+            break;
+        case nsXPTType::T_I64    :
+            if (gpr < 4) gpr+=2; else gpr=5, overflow+=2;
+            break;
+        case nsXPTType::T_U8     :
+        case nsXPTType::T_U16    :
+        case nsXPTType::T_U32    :
+            if (gpr < 5) gpr++; else overflow++;
+            break;
+        case nsXPTType::T_U64    :
+            if (gpr < 4) gpr+=2; else gpr=5, overflow+=2;
+            break;
+        case nsXPTType::T_FLOAT  :
+            if (fpr < 2) fpr++; else overflow++;
+            break;
+        case nsXPTType::T_DOUBLE :
+            if (fpr < 2) fpr++; else overflow+=2;
+            break;
+        case nsXPTType::T_BOOL   :
+        case nsXPTType::T_CHAR   :
+        case nsXPTType::T_WCHAR  :
+            if (gpr < 5) gpr++; else overflow++;
+            break;
+        default:
+            // all the others are plain pointer types
+            if (gpr < 5) gpr++; else overflow++;
+            break;
+        }
+    }
+    /* Round up number of overflow words to ensure stack
+       stays aligned to 8 bytes.  */
+    return (overflow + 1) & ~1;
+}
+
+static void
+invoke_copy_to_stack(uint32_t paramCount, nsXPTCVariant* s, uint32_t* d_ov, uint32_t overflow)
+{
+    uint32_t *d_gpr = d_ov + overflow; 
+    uint64_t *d_fpr = (uint64_t *)(d_gpr + 4);
+    uint32_t gpr = 1 /*this*/, fpr = 0;
+
+    for(uint32_t i = 0; i < paramCount; i++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            if (gpr < 5) 
+                *((void**)d_gpr) = s->ptr, d_gpr++, gpr++;
+            else
+                *((void**)d_ov ) = s->ptr, d_ov++;
+            continue;
+        }
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     : 
+            if (gpr < 5)
+                *((int32_t*) d_gpr) = s->val.i8, d_gpr++, gpr++;
+            else
+                *((int32_t*) d_ov ) = s->val.i8, d_ov++;
+            break;
+        case nsXPTType::T_I16    : 
+            if (gpr < 5)
+                *((int32_t*) d_gpr) = s->val.i16, d_gpr++, gpr++;
+            else
+                *((int32_t*) d_ov ) = s->val.i16, d_ov++;
+            break;
+        case nsXPTType::T_I32    : 
+            if (gpr < 5)
+                *((int32_t*) d_gpr) = s->val.i32, d_gpr++, gpr++;
+            else
+                *((int32_t*) d_ov ) = s->val.i32, d_ov++;
+            break;
+        case nsXPTType::T_I64    : 
+            if (gpr < 4)
+                *((int64_t*) d_gpr) = s->val.i64, d_gpr+=2, gpr+=2;
+            else
+                *((int64_t*) d_ov ) = s->val.i64, d_ov+=2, gpr=5;
+            break;
+        case nsXPTType::T_U8     : 
+            if (gpr < 5)
+                *((uint32_t*) d_gpr) = s->val.u8, d_gpr++, gpr++;
+            else
+                *((uint32_t*) d_ov ) = s->val.u8, d_ov++;
+            break;
+        case nsXPTType::T_U16    : 
+            if (gpr < 5)
+                *((uint32_t*)d_gpr) = s->val.u16, d_gpr++, gpr++;
+            else
+                *((uint32_t*)d_ov ) = s->val.u16, d_ov++;
+            break;
+        case nsXPTType::T_U32    : 
+            if (gpr < 5)
+                *((uint32_t*)d_gpr) = s->val.u32, d_gpr++, gpr++;
+            else
+                *((uint32_t*)d_ov ) = s->val.u32, d_ov++;
+            break;
+        case nsXPTType::T_U64    : 
+            if (gpr < 4)
+                *((uint64_t*)d_gpr) = s->val.u64, d_gpr+=2, gpr+=2;
+            else
+                *((uint64_t*)d_ov ) = s->val.u64, d_ov+=2, gpr=5;
+            break;
+        case nsXPTType::T_FLOAT  : 
+            if (fpr < 2)
+                *((float*)   d_fpr) = s->val.f, d_fpr++, fpr++;
+            else
+                *((float*)   d_ov ) = s->val.f, d_ov++;
+            break;
+        case nsXPTType::T_DOUBLE : 
+            if (fpr < 2)
+                *((double*)  d_fpr) = s->val.d, d_fpr++, fpr++;
+            else
+                *((double*)  d_ov ) = s->val.d, d_ov+=2;
+            break;
+        case nsXPTType::T_BOOL   : 
+            if (gpr < 5)
+                *((uint32_t*)d_gpr) = s->val.b, d_gpr++, gpr++;
+            else
+                *((uint32_t*)d_ov ) = s->val.b, d_ov++;
+            break;
+        case nsXPTType::T_CHAR   : 
+            if (gpr < 5)
+                *((uint32_t*)d_gpr) = s->val.c, d_gpr++, gpr++;
+            else
+                *((uint32_t*)d_ov ) = s->val.c, d_ov++;
+            break;
+        case nsXPTType::T_WCHAR  : 
+            if (gpr < 5)
+                *((uint32_t*)d_gpr) = s->val.wc, d_gpr++, gpr++;
+            else
+                *((uint32_t*)d_ov ) = s->val.wc, d_ov++;
+            break;
+        default:
+            // all the others are plain pointer types
+            if (gpr < 5) 
+                *((void**)   d_gpr) = s->val.p, d_gpr++, gpr++;
+            else
+                *((void**)   d_ov ) = s->val.p, d_ov++;
+            break;
+        }
+    }
+}
+
+typedef nsresult (*vtable_func)(nsISupports *, uint32_t, uint32_t, uint32_t, uint32_t, double, double);
+
+// Avoid AddressSanitizer instrumentation for the next function because it
+// depends on __builtin_alloca behavior and alignment that cannot be relied on
+// once the function is compiled with a version of ASan that has dynamic-alloca
+// instrumentation enabled.
+
+MOZ_ASAN_BLACKLIST
+EXPORT_XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                 uint32_t paramCount, nsXPTCVariant* params)
+{
+    vtable_func *vtable = *reinterpret_cast<vtable_func **>(that);
+    vtable_func method = vtable[methodIndex];
+    uint32_t overflow = invoke_count_words (paramCount, params);
+    uint32_t *stack_space = reinterpret_cast<uint32_t *>(__builtin_alloca((overflow + 8 /* 4 32-bits gpr + 2 64-bits fpr */) * 4));
+
+    invoke_copy_to_stack(paramCount, params, stack_space, overflow);
+
+    uint32_t *d_gpr = stack_space + overflow;
+    double *d_fpr = reinterpret_cast<double *>(d_gpr + 4);
+
+    return method(that, d_gpr[0], d_gpr[1], d_gpr[2], d_gpr[3],  d_fpr[0], d_fpr[1]);
+}
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_linux_s390x.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_linux_s390x.cpp
new file mode 100644
index 000000000..86478a850
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_linux_s390x.cpp
@@ -0,0 +1,190 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+
+static uint32_t
+invoke_count_words(uint32_t paramCount, nsXPTCVariant* s)
+{
+    uint32_t overflow = 0, gpr = 1 /*this*/, fpr = 0;
+    for(uint32_t i = 0; i < paramCount; i++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            if (gpr < 5) gpr++; else overflow++;
+            continue;
+        }
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     :
+        case nsXPTType::T_I16    :
+        case nsXPTType::T_I32    :
+        case nsXPTType::T_I64    :
+            if (gpr < 5) gpr++; else overflow++;
+            break;
+        case nsXPTType::T_U8     :
+        case nsXPTType::T_U16    :
+        case nsXPTType::T_U32    :
+        case nsXPTType::T_U64    :
+            if (gpr < 5) gpr++; else overflow++;
+            break;
+        case nsXPTType::T_FLOAT  :
+        case nsXPTType::T_DOUBLE :
+            if (fpr < 4) fpr++; else overflow++;
+            break;
+        case nsXPTType::T_BOOL   :
+        case nsXPTType::T_CHAR   :
+        case nsXPTType::T_WCHAR  :
+            if (gpr < 5) gpr++; else overflow++;
+            break;
+        default:
+            // all the others are plain pointer types
+            if (gpr < 5) gpr++; else overflow++;
+            break;
+        }
+    }
+    /* Round up number of overflow words to ensure stack
+       stays aligned to 8 bytes.  */
+    return (overflow + 1) & ~1;
+}
+
+static void
+invoke_copy_to_stack(uint32_t paramCount, nsXPTCVariant* s, uint64_t* d_ov, uint32_t overflow)
+{
+    uint64_t *d_gpr = d_ov + overflow; 
+    uint64_t *d_fpr = (uint64_t *)(d_gpr + 4);
+    uint32_t gpr = 1 /*this*/, fpr = 0;
+
+    for(uint32_t i = 0; i < paramCount; i++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            if (gpr < 5) 
+                *((void**)d_gpr) = s->ptr, d_gpr++, gpr++;
+            else
+                *((void**)d_ov ) = s->ptr, d_ov++;
+            continue;
+        }
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     : 
+            if (gpr < 5)
+                *((int64_t*) d_gpr) = s->val.i8, d_gpr++, gpr++;
+            else
+                *((int64_t*) d_ov ) = s->val.i8, d_ov++;
+            break;
+        case nsXPTType::T_I16    : 
+            if (gpr < 5)
+                *((int64_t*) d_gpr) = s->val.i16, d_gpr++, gpr++;
+            else
+                *((int64_t*) d_ov ) = s->val.i16, d_ov++;
+            break;
+        case nsXPTType::T_I32    : 
+            if (gpr < 5)
+                *((int64_t*) d_gpr) = s->val.i32, d_gpr++, gpr++;
+            else
+                *((int64_t*) d_ov ) = s->val.i32, d_ov++;
+            break;
+        case nsXPTType::T_I64    : 
+            if (gpr < 5)
+                *((int64_t*) d_gpr) = s->val.i64, d_gpr++, gpr++;
+            else
+                *((int64_t*) d_ov ) = s->val.i64, d_ov++;
+            break;
+        case nsXPTType::T_U8     : 
+            if (gpr < 5)
+                *((uint64_t*) d_gpr) = s->val.u8, d_gpr++, gpr++;
+            else
+                *((uint64_t*) d_ov ) = s->val.u8, d_ov++;
+            break;
+        case nsXPTType::T_U16    : 
+            if (gpr < 5)
+                *((uint64_t*)d_gpr) = s->val.u16, d_gpr++, gpr++;
+            else
+                *((uint64_t*)d_ov ) = s->val.u16, d_ov++;
+            break;
+        case nsXPTType::T_U32    : 
+            if (gpr < 5)
+                *((uint64_t*)d_gpr) = s->val.u32, d_gpr++, gpr++;
+            else
+                *((uint64_t*)d_ov ) = s->val.u32, d_ov++;
+            break;
+        case nsXPTType::T_U64    : 
+            if (gpr < 5)
+                *((uint64_t*)d_gpr) = s->val.u64, d_gpr++, gpr++;
+            else
+                *((uint64_t*)d_ov ) = s->val.u64, d_ov++;
+            break;
+        case nsXPTType::T_FLOAT  : 
+            if (fpr < 4)
+                *((float*)   d_fpr)    = s->val.f, d_fpr++, fpr++;
+            else
+                *(((float*)  d_ov )+1) = s->val.f, d_ov++;
+            break;
+        case nsXPTType::T_DOUBLE : 
+            if (fpr < 4)
+                *((double*)  d_fpr) = s->val.d, d_fpr++, fpr++;
+            else
+                *((double*)  d_ov ) = s->val.d, d_ov++;
+            break;
+        case nsXPTType::T_BOOL   : 
+            if (gpr < 5)
+                *((uint64_t*)d_gpr) = s->val.b, d_gpr++, gpr++;
+            else
+                *((uint64_t*)d_ov ) = s->val.b, d_ov++;
+            break;
+        case nsXPTType::T_CHAR   : 
+            if (gpr < 5)
+                *((uint64_t*)d_gpr) = s->val.c, d_gpr++, gpr++;
+            else
+                *((uint64_t*)d_ov ) = s->val.c, d_ov++;
+            break;
+        case nsXPTType::T_WCHAR  : 
+            if (gpr < 5)
+                *((uint64_t*)d_gpr) = s->val.wc, d_gpr++, gpr++;
+            else
+                *((uint64_t*)d_ov ) = s->val.wc, d_ov++;
+            break;
+        default:
+            // all the others are plain pointer types
+            if (gpr < 5) 
+                *((void**)   d_gpr) = s->val.p, d_gpr++, gpr++;
+            else
+                *((void**)   d_ov ) = s->val.p, d_ov++;
+            break;
+        }
+    }
+}
+
+typedef nsresult (*vtable_func)(nsISupports *, uint64_t, uint64_t, uint64_t, uint64_t, double, double, double, double);
+
+// Avoid AddressSanitizer instrumentation for the next function because it
+// depends on __builtin_alloca behavior and alignment that cannot be relied on
+// once the function is compiled with a version of ASan that has dynamic-alloca
+// instrumentation enabled.
+
+MOZ_ASAN_BLACKLIST
+EXPORT_XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                 uint32_t paramCount, nsXPTCVariant* params)
+{
+    vtable_func *vtable = *reinterpret_cast<vtable_func **>(that);
+    vtable_func method = vtable[methodIndex];
+    uint64_t overflow = invoke_count_words (paramCount, params);
+    uint64_t *stack_space = reinterpret_cast<uint64_t *>(__builtin_alloca((overflow + 8 /* 4 64-bits gpr + 4 64-bits fpr */) * 8));
+    uint64_t result;
+
+    invoke_copy_to_stack(paramCount, params, stack_space, overflow);
+
+    uint64_t *d_gpr = stack_space + overflow;
+    double *d_fpr = reinterpret_cast<double *>(d_gpr + 4);
+
+    return method(that, d_gpr[0], d_gpr[1], d_gpr[2], d_gpr[3], d_fpr[0], d_fpr[1], d_fpr[2], d_fpr[3]);
+}
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_mips.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_mips.cpp
new file mode 100644
index 000000000..f6585e7f0
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_mips.cpp
@@ -0,0 +1,99 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * Version: MPL 1.1
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* This code is for MIPS using the O32 ABI. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+#include <stdint.h>
+
+extern "C" uint32_t
+invoke_count_words(uint32_t paramCount, nsXPTCVariant* s)
+{
+    // Count a word for a0 even though it's never stored or loaded
+    // We do this only for alignment of register pairs.
+    uint32_t result = 1;
+    for (uint32_t i = 0; i < paramCount; i++, result++, s++)
+    {
+        if (s->IsPtrData())
+            continue;
+
+        switch(s->type)
+        {
+        case nsXPTType::T_I64    :
+        case nsXPTType::T_U64    :
+        case nsXPTType::T_DOUBLE :
+	    if (result & 1)
+		result++;
+	    result++;
+	    break;
+
+        default:
+            break;
+        }
+    }
+    return (result + 1) & ~(uint32_t)1;
+}
+
+extern "C" void
+invoke_copy_to_stack(uint32_t* d, uint32_t paramCount,
+                     nsXPTCVariant* s)
+{
+    // Skip the unused a0 slot, which we keep only for register pair alignment.
+    d++;
+
+    for (uint32_t i = 0; i < paramCount; i++, d++, s++)
+    {
+        if (s->IsPtrData())
+        {
+            *((void**)d) = s->ptr;
+            continue;
+        }
+
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     : *d = (uint32_t) s->val.i8;   break;
+        case nsXPTType::T_I16    : *d = (uint32_t) s->val.i16;  break;
+        case nsXPTType::T_I32    : *d = (uint32_t) s->val.i32;  break;
+        case nsXPTType::T_I64    :
+            if ((intptr_t)d & 4) d++;
+            *((int64_t*) d)  = s->val.i64;    d++;
+            break;
+        case nsXPTType::T_U8     : *d = (uint32_t) s->val.u8;   break;
+        case nsXPTType::T_U16    : *d = (uint32_t) s->val.u16;  break;
+        case nsXPTType::T_U32    : *d = (uint32_t) s->val.u32;  break;
+        case nsXPTType::T_U64    :
+            if ((intptr_t)d & 4) d++;
+            *((uint64_t*) d) = s->val.u64;    d++;
+            break;
+        case nsXPTType::T_FLOAT  : *((float*)   d) = s->val.f;  break;
+        case nsXPTType::T_DOUBLE :
+            if ((intptr_t)d & 4) d++;
+            *((double*)   d) = s->val.d;      d++;
+            break;
+        case nsXPTType::T_BOOL   : *d = (bool)  s->val.b;     break;
+        case nsXPTType::T_CHAR   : *d = (char)    s->val.c;     break;
+        case nsXPTType::T_WCHAR  : *d = (wchar_t) s->val.wc;    break;
+        default:
+            *((void**)d) = s->val.p;
+            break;
+        }
+    }
+}
+
+extern "C" nsresult _NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                                        uint32_t paramCount,
+                                        nsXPTCVariant* params);
+
+EXPORT_XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                   uint32_t paramCount, nsXPTCVariant* params)
+{
+    return _NS_InvokeByIndex(that, methodIndex, paramCount, params);
+}
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_mips64.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_mips64.cpp
new file mode 100644
index 000000000..1dd54f96f
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_mips64.cpp
@@ -0,0 +1,142 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+#if (_MIPS_SIM != _ABIN32) && (_MIPS_SIM != _ABI64)
+#error "This code is for MIPS n32/n64 only"
+#endif
+
+extern "C" uint32_t
+invoke_count_words(uint32_t paramCount, nsXPTCVariant* s)
+{
+    return paramCount;
+}
+
+extern "C" void
+invoke_copy_to_stack(uint64_t* d, uint32_t paramCount,
+                     nsXPTCVariant* s, uint64_t *regs)
+{
+#define N_ARG_REGS       7       /* 8 regs minus 1 for "this" ptr */
+
+    for (uint32_t i = 0; i < paramCount; i++, s++)
+    {
+        if (s->IsPtrData()) {
+            if (i < N_ARG_REGS)
+                regs[i] = (uint64_t)s->ptr;
+            else
+                *d++ = (uint64_t)s->ptr;
+            continue;
+        }
+        switch (s->type) {
+        //
+        // signed types first
+        //
+        case nsXPTType::T_I8:
+            if (i < N_ARG_REGS)
+                ((int64_t*)regs)[i] = s->val.i8;
+            else
+                *d++ = s->val.i8;
+            break;
+        case nsXPTType::T_I16:
+            if (i < N_ARG_REGS)
+                ((int64_t*)regs)[i] = s->val.i16;
+            else
+                *d++ = s->val.i16;
+            break;
+        case nsXPTType::T_I32:
+            if (i < N_ARG_REGS)
+                ((int64_t*)regs)[i] = s->val.i32;
+            else
+                *d++ = s->val.i32;
+            break;
+        case nsXPTType::T_I64:
+            if (i < N_ARG_REGS)
+                ((int64_t*)regs)[i] = s->val.i64;
+            else
+                *d++ = s->val.i64;
+            break;
+        //
+        // unsigned types next
+        //
+        case nsXPTType::T_U8:
+            if (i < N_ARG_REGS)
+                regs[i] = s->val.u8;
+            else
+                *d++ = s->val.u8;
+            break;
+        case nsXPTType::T_U16:
+            if (i < N_ARG_REGS)
+                regs[i] = s->val.u16;
+            else
+                *d++ = s->val.u16;
+            break;
+        case nsXPTType::T_U32:
+            if (i < N_ARG_REGS)
+		// 32-bit values need to be sign-extended
+		// in register, so use the signed value.
+                regs[i] = s->val.i32;
+            else
+                *d++ = s->val.u32;
+            break;
+        case nsXPTType::T_U64:
+            if (i < N_ARG_REGS)
+                regs[i] = s->val.u64;
+            else
+                *d++ = s->val.u64;
+            break;
+        case nsXPTType::T_FLOAT:
+            if (i < N_ARG_REGS)
+                *(float*)&regs[i] = s->val.f;
+            else
+                *(float*)d++ = s->val.f;
+            break;
+        case nsXPTType::T_DOUBLE:
+            if (i < N_ARG_REGS)
+                *(double*)&regs[i] = s->val.d;
+            else
+                *(double*)d++ = s->val.d;
+            break;
+        case nsXPTType::T_BOOL:
+            if (i < N_ARG_REGS)
+                regs[i] = s->val.b;
+            else
+                *d++ = s->val.b;
+            break;
+        case nsXPTType::T_CHAR:
+            if (i < N_ARG_REGS)
+                regs[i] = s->val.c;
+            else
+                *d++ = s->val.c;
+            break;
+        case nsXPTType::T_WCHAR:
+            if (i < N_ARG_REGS)
+                regs[i] = s->val.wc;
+            else
+                *d++ = s->val.wc;
+            break;
+        default:
+            // all the others are plain pointer types
+            if (i < N_ARG_REGS)
+                regs[i] = (uint64_t)s->val.p;
+            else
+               *d++ = (uint64_t)s->val.p;
+            break;
+        }
+    }
+}
+
+extern "C" nsresult _NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                                        uint32_t paramCount,
+                                        nsXPTCVariant* params);
+
+EXPORT_XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                   uint32_t paramCount, nsXPTCVariant* params)
+{
+    return _NS_InvokeByIndex(that, methodIndex, paramCount, params);
+}
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_netbsd_m68k.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_netbsd_m68k.cpp
new file mode 100644
index 000000000..47e0e7666
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_netbsd_m68k.cpp
@@ -0,0 +1,143 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+// Remember that these 'words' are 32bit DWORDS
+
+#if !defined(__NetBSD__) || !defined(__m68k__)
+#error This code is for NetBSD/m68k only
+#endif
+
+extern "C" {
+    static uint32_t
+    invoke_count_words(uint32_t paramCount, nsXPTCVariant* s)
+    {
+        uint32_t result = 0;
+        for(uint32_t i = 0; i < paramCount; i++, s++)
+        {
+            if(s->IsPtrData())
+            {
+                result++;
+                continue;
+            }
+            switch(s->type)
+            {
+            case nsXPTType::T_I8     :
+            case nsXPTType::T_I16    :
+            case nsXPTType::T_I32    :
+                result++;
+                break;
+            case nsXPTType::T_I64    :
+                result+=2;
+                break;
+            case nsXPTType::T_U8     :
+            case nsXPTType::T_U16    :
+            case nsXPTType::T_U32    :
+                result++;
+                break;
+            case nsXPTType::T_U64    :
+                result+=2;
+                break;
+            case nsXPTType::T_FLOAT  :
+                result++;
+                break;
+            case nsXPTType::T_DOUBLE :
+                result+=2;
+                break;
+            case nsXPTType::T_BOOL   :
+            case nsXPTType::T_CHAR   :
+            case nsXPTType::T_WCHAR  :
+                result++;
+                break;
+            default:
+                // all the others are plain pointer types
+                result++;
+                break;
+            }
+        }
+        return result;
+    }
+
+    static void
+    invoke_copy_to_stack(uint32_t* d, uint32_t paramCount, nsXPTCVariant* s)
+    {
+        for(uint32_t i = 0; i < paramCount; i++, d++, s++)
+        {
+            if(s->IsPtrData())
+            {
+                *((void**)d) = s->ptr;
+                continue;
+            }
+            switch(s->type)
+            {
+            // 8 and 16 bit types should be promoted to 32 bits when copying
+            // onto the stack.
+            case nsXPTType::T_I8     : *((uint32_t*)d) = s->val.i8;          break;
+            case nsXPTType::T_I16    : *((uint32_t*)d) = s->val.i16;         break;
+            case nsXPTType::T_I32    : *((int32_t*) d) = s->val.i32;         break;
+            case nsXPTType::T_I64    : *((int64_t*) d) = s->val.i64; d++;    break;
+            case nsXPTType::T_U8     : *((uint32_t*)d) = s->val.u8;          break;
+            case nsXPTType::T_U16    : *((uint32_t*)d) = s->val.u16;         break;
+            case nsXPTType::T_U32    : *((uint32_t*)d) = s->val.u32;         break;
+            case nsXPTType::T_U64    : *((uint64_t*)d) = s->val.u64; d++;    break;
+            case nsXPTType::T_FLOAT  : *((float*)   d) = s->val.f;           break;
+            case nsXPTType::T_DOUBLE : *((double*)  d) = s->val.d;   d++;    break;
+            case nsXPTType::T_BOOL   : *((uint32_t*)d) = s->val.b;           break;
+            case nsXPTType::T_CHAR   : *((uint32_t*)d) = s->val.c;           break;
+            // wchar_t is an int (32 bits) on NetBSD
+            case nsXPTType::T_WCHAR  : *((wchar_t*) d) = s->val.wc;          break;
+            default:
+                // all the others are plain pointer types
+                *((void**)d) = s->val.p;
+                break;
+            }
+        }
+    }
+}
+
+XPTC_PUBLIC_API(nsresult)
+XPTC_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                   uint32_t paramCount, nsXPTCVariant* params)
+{
+    uint32_t result;
+
+ __asm__ __volatile__(
+    "movl  %4, sp@-\n\t"
+    "movl  %3, sp@-\n\t"
+    "jbsr  _invoke_count_words\n\t"     /* count words */
+    "addql #8, sp\n\t"
+    "lsll  #2, d0\n\t"      /* *= 4 */
+    "movl  sp, a2\n\t"	    /* save original sp */
+    "subl  d0, sp\n\t"      /* make room for params */
+    "movl  sp, a0\n\t"
+    "movl  %4, sp@-\n\t"
+    "movl  %3, sp@-\n\t"
+    "movl  a0, sp@-\n\t"
+    "jbsr  _invoke_copy_to_stack\n\t"   /* copy params */
+    "addl  #12, sp\n\t"
+    "movl  %1, a0\n\t"
+    "movl  a0@, a1\n\t"
+    "movl  %2, d0\n\t"      /* function index */
+    "movl  a0, d1\n\t"
+    "movw  a1@(8,d0:l:8), a0\n\t"
+    "addl  a0, d1\n\t"
+    "movl  a1@(12,d0:l:8), a1\n\t"
+    "movl  d1, sp@-\n\t"
+    "jbsr  a1@\n\t"
+    "movl  a2, sp\n\t"	    /* restore original sp */
+    "movl  d0, %0\n\t"
+    : "=g" (result)         /* %0 */
+    : "g" (that),           /* %1 */
+      "g" (methodIndex),    /* %2 */
+      "g" (paramCount),     /* %3 */
+      "g" (params)          /* %4 */
+    : "a0", "a1", "a2", "d0", "d1", "memory"
+    );
+  
+  return result;
+}
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_pa32.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_pa32.cpp
new file mode 100644
index 000000000..0e6d28fbd
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_pa32.cpp
@@ -0,0 +1,149 @@
+
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "xptcprivate.h"
+
+#if _HPUX
+#error "This code is for HP-PA RISC 32 bit mode only"
+#endif
+
+#include <alloca.h>
+
+typedef unsigned nsXPCVariant;
+
+extern "C" int32_t
+invoke_count_bytes(nsISupports* that, const uint32_t methodIndex,
+  const uint32_t paramCount, const nsXPTCVariant* s)
+{
+  int32_t result = 4; /* variant records do not include self pointer */
+
+  /* counts the number of bytes required by the argument stack,
+     64 bit integer, and double requires 8 bytes.  All else requires
+     4 bytes.
+   */
+
+  {
+    uint32_t indx;
+    for (indx = paramCount; indx > 0; --indx, ++s)
+    {
+      if (! s->IsPtrData())
+      {
+        if (s->type == nsXPTType::T_I64 || s->type == nsXPTType::T_U64 ||
+            s->type == nsXPTType::T_DOUBLE)
+        {
+          /* 64 bit integer and double aligned on 8 byte boundaries */
+          result += (result & 4) + 8;
+          continue;
+        }
+      }
+      result += 4; /* all other cases use 4 bytes */
+    }
+  }
+  result -= 72; /* existing stack buffer is 72 bytes */
+  if (result < 0)
+    return 0;
+  {
+    /* round up to 64 bytes boundary */
+    int32_t remainder = result & 63;
+    return (remainder == 0) ? result : (result + 64 - remainder);
+  }
+}
+
+extern "C" uint32_t
+invoke_copy_to_stack(uint32_t* d,
+  const uint32_t paramCount, nsXPTCVariant* s)
+{
+
+  typedef struct
+  {
+    uint32_t hi;
+    uint32_t lo;
+  } DU;
+
+  uint32_t* dest = d;
+  nsXPTCVariant* source = s;
+  /* we clobber param vars by copying stuff on stack, have to use local var */
+
+  uint32_t floatflags = 0;
+  /* flag indicating which floating point registers to load */
+
+  uint32_t regwords = 1; /* register 26 is reserved for ptr to 'that' */
+  uint32_t indx;
+
+  for (indx = paramCount; indx > 0; --indx, --dest, ++source)
+  {
+    if (source->IsPtrData())
+    {
+      *((void**) dest) = source->ptr;
+      ++regwords;
+      continue;
+    }
+    switch (source->type)
+    {
+    case nsXPTType::T_I8    : *((int32_t*) dest) = source->val.i8;  break;
+    case nsXPTType::T_I16   : *((int32_t*) dest) = source->val.i16; break;
+    case nsXPTType::T_I32   : *((int32_t*) dest) = source->val.i32; break;
+    case nsXPTType::T_I64   :
+    case nsXPTType::T_U64   :
+      if (regwords & 1)
+      {
+        /* align on double word boundary */
+        --dest;
+        ++regwords;
+      }
+      *((uint32_t*) dest) = ((DU *) source)->lo;
+      *((uint32_t*) --dest) = ((DU *) source)->hi;
+      /* big endian - hi word in low addr */
+      regwords += 2;
+      continue;
+    case nsXPTType::T_DOUBLE :
+      if (regwords & 1)
+      {
+        /* align on double word boundary */
+        --dest;
+        ++regwords;
+      }
+      switch (regwords) /* load double precision float register */
+      {
+      case 2:
+        floatflags |= 1;
+      }
+      *((uint32_t*) dest) = ((DU *) source)->lo;
+      *((uint32_t*) --dest) = ((DU *) source)->hi;
+      /* big endian - hi word in low addr */
+      regwords += 2;
+      continue;
+    case nsXPTType::T_FLOAT :
+      switch (regwords) /* load single precision float register */
+      {
+      case 1:
+        floatflags |= 2;
+        break;
+      case 2:
+        floatflags |= 4;
+        break;
+      case 3:
+        floatflags |= 8;
+      }
+      *((float*) dest) = source->val.f;
+      break;
+    case nsXPTType::T_U8    : *((uint32_t*) (dest)) = source->val.u8; break;
+    case nsXPTType::T_U16   : *((uint32_t*) (dest)) = source->val.u16; break;
+    case nsXPTType::T_U32   : *((uint32_t*) (dest)) = source->val.u32; break;
+    case nsXPTType::T_BOOL  : *((uint32_t*) (dest)) = source->val.b; break;
+    case nsXPTType::T_CHAR  : *((uint32_t*) (dest)) = source->val.c; break;
+    case nsXPTType::T_WCHAR : *((int32_t*)  (dest)) = source->val.wc; break;
+
+    default:
+      // all the others are plain pointer types
+      *((void**) dest) = source->val.p;
+    }
+    ++regwords;
+  }
+  return floatflags;
+}
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc64_linux.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc64_linux.cpp
new file mode 100644
index 000000000..c93dc4621
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc64_linux.cpp
@@ -0,0 +1,97 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Platform specific code to invoke XPCOM methods on native objects
+
+// The purpose of NS_InvokeByIndex() is to map a platform
+// independent call to the platform ABI. To do that,
+// NS_InvokeByIndex() has to determine the method to call via vtable
+// access. The parameters for the method are read from the
+// nsXPTCVariant* and prepared for the native ABI.
+
+// The PowerPC64 platform ABI can be found here:
+// http://www.freestandards.org/spec/ELF/ppc64/
+// and in particular:
+// http://www.freestandards.org/spec/ELF/ppc64/PPC-elf64abi-1.9.html#FUNC-CALL
+
+#include <stdio.h>
+#include "xptcprivate.h"
+
+// 8 integral parameters are passed in registers, not including 'that'
+#define GPR_COUNT     7
+
+// 8 floating point parameters are passed in registers, floats are
+// promoted to doubles when passed in registers
+#define FPR_COUNT     13
+
+extern "C" uint32_t
+invoke_count_words(uint32_t paramCount, nsXPTCVariant* s)
+{
+    return uint32_t(((paramCount * 2) + 3) & ~3);
+}
+
+extern "C" void
+invoke_copy_to_stack(uint64_t* gpregs,
+                     double* fpregs,
+                     uint32_t paramCount,
+                     nsXPTCVariant* s, 
+                     uint64_t* d)
+{
+    uint64_t tempu64;
+
+    for(uint32_t i = 0; i < paramCount; i++, s++) {
+        if(s->IsPtrData())
+            tempu64 = (uint64_t) s->ptr;
+        else {
+            switch(s->type) {
+            case nsXPTType::T_FLOAT:                                  break;
+            case nsXPTType::T_DOUBLE:                                 break;
+            case nsXPTType::T_I8:     tempu64 = s->val.i8;            break;
+            case nsXPTType::T_I16:    tempu64 = s->val.i16;           break;
+            case nsXPTType::T_I32:    tempu64 = s->val.i32;           break;
+            case nsXPTType::T_I64:    tempu64 = s->val.i64;           break;
+            case nsXPTType::T_U8:     tempu64 = s->val.u8;            break;
+            case nsXPTType::T_U16:    tempu64 = s->val.u16;           break;
+            case nsXPTType::T_U32:    tempu64 = s->val.u32;           break;
+            case nsXPTType::T_U64:    tempu64 = s->val.u64;           break;
+            case nsXPTType::T_BOOL:   tempu64 = s->val.b;             break;
+            case nsXPTType::T_CHAR:   tempu64 = s->val.c;             break;
+            case nsXPTType::T_WCHAR:  tempu64 = s->val.wc;            break;
+            default:                  tempu64 = (uint64_t) s->val.p;  break;
+            }
+        }
+
+        if (!s->IsPtrData() && s->type == nsXPTType::T_DOUBLE) {
+            if (i < FPR_COUNT)
+                fpregs[i]    = s->val.d;
+            else
+                *(double *)d = s->val.d;
+        }
+        else if (!s->IsPtrData() && s->type == nsXPTType::T_FLOAT) {
+            if (i < FPR_COUNT) {
+                fpregs[i]   = s->val.f; // if passed in registers, floats are promoted to doubles
+            } else {
+                float *p = (float *)d;
+#ifndef __LITTLE_ENDIAN__
+                p++;
+#endif
+                *p = s->val.f;
+            }
+        }
+        else {
+            if (i < GPR_COUNT)
+                gpregs[i] = tempu64;
+            else
+                *d = tempu64;
+        }
+        if (i >= 7)
+            d++;
+    }
+}
+
+EXPORT_XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                   uint32_t paramCount, nsXPTCVariant* params);
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc_aix.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc_aix.cpp
new file mode 100644
index 000000000..ba2a5dab0
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc_aix.cpp
@@ -0,0 +1,74 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+#ifndef AIX
+#error "This code is for PowerPC only"
+#endif
+
+extern "C" void
+invoke_copy_to_stack(uint32_t* d, uint32_t paramCount, nsXPTCVariant* s, double *fprData)
+{
+/*
+    We need to copy the parameters for this function to locals and use them
+    from there since the parameters occupy the same stack space as the stack
+    we're trying to populate.
+*/
+    uint32_t *l_d = d;
+    nsXPTCVariant *l_s = s;
+    uint32_t l_paramCount = paramCount, fpCount = 0;
+    double *l_fprData = fprData;
+
+    typedef struct {
+        uint32_t hi;
+        uint32_t lo;
+    } DU;               // have to move 64 bit entities as 32 bit halves since
+                        // stack slots are not guaranteed 16 byte aligned
+
+    for(uint32_t i = 0; i < l_paramCount; i++, l_d++, l_s++)
+    {
+        if(l_s->IsPtrData())
+        {
+            *((void**)l_d) = l_s->ptr;
+            continue;
+        }
+        switch(l_s->type)
+        {
+        case nsXPTType::T_I8     : *((int32_t*)  l_d) = l_s->val.i8;          break;
+        case nsXPTType::T_I16    : *((int32_t*)  l_d) = l_s->val.i16;         break;
+        case nsXPTType::T_I32    : *((int32_t*)  l_d) = l_s->val.i32;         break;
+        case nsXPTType::T_I64    : 
+        case nsXPTType::T_U64    :
+            *((uint32_t*) l_d++) = ((DU *)l_s)->hi;
+            *((uint32_t*) l_d) = ((DU *)l_s)->lo;
+            break;
+        case nsXPTType::T_DOUBLE :
+            *((uint32_t*) l_d++) = ((DU *)l_s)->hi;
+            *((uint32_t*) l_d) = ((DU *)l_s)->lo;
+            if(fpCount < 13)
+                l_fprData[fpCount++] = l_s->val.d;
+            break;
+        case nsXPTType::T_U8     : *((uint32_t*) l_d) = l_s->val.u8;          break;
+        case nsXPTType::T_U16    : *((uint32_t*) l_d) = l_s->val.u16;         break;
+        case nsXPTType::T_U32    : *((uint32_t*) l_d) = l_s->val.u32;         break;
+        case nsXPTType::T_FLOAT  :
+            *((float*)  l_d) = l_s->val.f;
+            if(fpCount < 13)
+                l_fprData[fpCount++] = l_s->val.f;
+            break;
+        case nsXPTType::T_BOOL   : *((uint32_t*) l_d) = l_s->val.b;           break;
+        case nsXPTType::T_CHAR   : *((uint32_t*) l_d) = l_s->val.c;           break;
+        case nsXPTType::T_WCHAR  : *((int32_t*)  l_d) = l_s->val.wc;          break;
+        default:
+            // all the others are plain pointer types
+            *((void**)l_d) = l_s->val.p;
+            break;
+        }
+    }
+}
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc_aix64.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc_aix64.cpp
new file mode 100644
index 000000000..616c2f687
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc_aix64.cpp
@@ -0,0 +1,63 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+#ifdef _AIX
+
+extern "C" void
+invoke_copy_to_stack(uint64_t* d, uint32_t paramCount, nsXPTCVariant* s, double *fprData)
+{
+/*
+    We need to copy the parameters for this function to locals and use them
+    from there since the parameters occupy the same stack space as the stack
+    we're trying to populate.
+*/
+    uint64_t *l_d = d;
+    nsXPTCVariant *l_s = s;
+    uint32_t l_paramCount = paramCount, fpCount = 0;
+    double *l_fprData = fprData;
+
+    for(uint32_t i = 0; i < l_paramCount; i++, l_d++, l_s++)
+    {
+        if(l_s->IsPtrData())
+        {
+            *l_d = (uint64_t)l_s->ptr;
+            continue;
+        }
+        switch(l_s->type)
+        {
+        case nsXPTType::T_I8:    *l_d = (uint64_t)l_s->val.i8;   break;
+        case nsXPTType::T_I16:   *l_d = (uint64_t)l_s->val.i16;  break;
+        case nsXPTType::T_I32:   *l_d = (uint64_t)l_s->val.i32;  break;
+        case nsXPTType::T_I64:   *l_d = (uint64_t)l_s->val.i64;  break;
+        case nsXPTType::T_U8:    *l_d = (uint64_t)l_s->val.u8;   break;
+        case nsXPTType::T_U16:   *l_d = (uint64_t)l_s->val.u16;  break;
+        case nsXPTType::T_U32:   *l_d = (uint64_t)l_s->val.u32;  break;
+        case nsXPTType::T_U64:   *l_d = (uint64_t)l_s->val.u64;  break;
+        case nsXPTType::T_BOOL:  *l_d = (uint64_t)l_s->val.b;    break;
+        case nsXPTType::T_CHAR:  *l_d = (uint64_t)l_s->val.c;    break;
+        case nsXPTType::T_WCHAR: *l_d = (uint64_t)l_s->val.wc;   break;
+
+        case nsXPTType::T_DOUBLE:
+            *((double*)l_d) = l_s->val.d;
+            if(fpCount < 13)
+                l_fprData[fpCount++] = l_s->val.d;
+            break;
+        case nsXPTType::T_FLOAT:
+            *((float*)l_d) = l_s->val.f;
+            if(fpCount < 13)
+                l_fprData[fpCount++] = l_s->val.f;
+            break;
+        default:
+            // all the others are plain pointer types
+            *l_d = (uint64_t)l_s->val.p;
+            break;
+        }
+    }
+}
+#endif
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc_linux.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc_linux.cpp
new file mode 100644
index 000000000..deb72db8f
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc_linux.cpp
@@ -0,0 +1,128 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Platform specific code to invoke XPCOM methods on native objects
+
+// The purpose of NS_InvokeByIndex() is to map a platform
+// indepenpent call to the platform ABI. To do that,
+// NS_InvokeByIndex() has to determine the method to call via vtable
+// access. The parameters for the method are read from the
+// nsXPTCVariant* and prepared for th native ABI.  For the Linux/PPC
+// ABI this means that the first 8 integral and floating point
+// parameters are passed in registers.
+
+#include "xptcprivate.h"
+
+// 8 integral parameters are passed in registers
+#define GPR_COUNT     8
+
+// With hardfloat support 8 floating point parameters are passed in registers,
+// floats are promoted to doubles when passed in registers
+// In Softfloat mode, everything is handled via gprs
+#ifndef __NO_FPRS__
+#define FPR_COUNT     8
+#endif
+extern "C" uint32_t
+invoke_count_words(uint32_t paramCount, nsXPTCVariant* s)
+{
+  return uint32_t(((paramCount * 2) + 3) & ~3);
+}
+
+extern "C" void
+invoke_copy_to_stack(uint32_t* d,
+                     uint32_t paramCount,
+                     nsXPTCVariant* s, 
+                     uint32_t* gpregs,
+                     double* fpregs)
+{
+    uint32_t gpr = 1; // skip one GP reg for 'that'
+#ifndef __NO_FPRS__
+    uint32_t fpr = 0;
+#endif
+    uint32_t tempu32;
+    uint64_t tempu64;
+    
+    for(uint32_t i = 0; i < paramCount; i++, s++) {
+        if(s->IsPtrData()) {
+            if(s->type == nsXPTType::T_JSVAL)
+                tempu32 = (uint32_t) &s->ptr;
+            else
+                tempu32 = (uint32_t) s->ptr;
+        }
+        else {
+            switch(s->type) {
+            case nsXPTType::T_FLOAT:                                  break;
+            case nsXPTType::T_DOUBLE:                                 break;
+            case nsXPTType::T_I8:     tempu32 = s->val.i8;            break;
+            case nsXPTType::T_I16:    tempu32 = s->val.i16;           break;
+            case nsXPTType::T_I32:    tempu32 = s->val.i32;           break;
+            case nsXPTType::T_I64:    tempu64 = s->val.i64;           break;
+            case nsXPTType::T_U8:     tempu32 = s->val.u8;            break;
+            case nsXPTType::T_U16:    tempu32 = s->val.u16;           break;
+            case nsXPTType::T_U32:    tempu32 = s->val.u32;           break;
+            case nsXPTType::T_U64:    tempu64 = s->val.u64;           break;
+            case nsXPTType::T_BOOL:   tempu32 = s->val.b;             break;
+            case nsXPTType::T_CHAR:   tempu32 = s->val.c;             break;
+            case nsXPTType::T_WCHAR:  tempu32 = s->val.wc;            break;
+            default:                  tempu32 = (uint32_t) s->val.p;  break;
+            }
+        }
+
+        if (!s->IsPtrData() && s->type == nsXPTType::T_DOUBLE) {
+#ifndef __NO_FPRS__
+            if (fpr < FPR_COUNT)
+                fpregs[fpr++]    = s->val.d;
+#else
+            if (gpr & 1)
+                gpr++;
+            if ((gpr + 1) < GPR_COUNT) {
+                *((double*) &gpregs[gpr]) = s->val.d;
+                gpr += 2;
+            }
+#endif
+            else {
+                if ((uint32_t) d & 4) d++; // doubles are 8-byte aligned on stack
+                *((double*) d) = s->val.d;
+                d += 2;
+            }
+        }
+        else if (!s->IsPtrData() && s->type == nsXPTType::T_FLOAT) {
+#ifndef __NO_FPRS__
+            if (fpr < FPR_COUNT)
+                fpregs[fpr++]   = s->val.f; // if passed in registers, floats are promoted to doubles
+#else
+            if (gpr < GPR_COUNT)
+                *((float*) &gpregs[gpr++]) = s->val.f;
+#endif
+            else
+                *((float*) d++) = s->val.f;
+        }
+        else if (!s->IsPtrData() && (s->type == nsXPTType::T_I64
+                                     || s->type == nsXPTType::T_U64)) {
+            if (gpr & 1) gpr++; // longlongs are aligned in odd/even register pairs, eg. r5/r6
+            if ((gpr + 1) < GPR_COUNT) {
+                *((uint64_t*) &gpregs[gpr]) = tempu64;
+                gpr += 2;
+            }
+            else {
+                if ((uint32_t) d & 4) d++; // longlongs are 8-byte aligned on stack
+                *((uint64_t*) d)            = tempu64;
+                d += 2;
+            }
+        }
+        else {
+            if (gpr < GPR_COUNT)
+                gpregs[gpr++] = tempu32;
+            else
+                *d++          = tempu32;
+        }
+        
+    }
+}
+
+extern "C"
+EXPORT_XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                 uint32_t paramCount, nsXPTCVariant* params);
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc_netbsd.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc_netbsd.cpp
new file mode 100644
index 000000000..515e8c50b
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc_netbsd.cpp
@@ -0,0 +1,115 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Platform specific code to invoke XPCOM methods on native objects
+
+// The purpose of XPTC_InvokeByIndex() is to map a platform
+// indepenpent call to the platform ABI. To do that,
+// XPTC_InvokeByIndex() has to determine the method to call via vtable
+// access. The parameters for the method are read from the
+// nsXPTCVariant* and prepared for the native ABI.  For the Linux/PPC
+// ABI this means that the first 8 integral and floating point
+// parameters are passed in registers.
+
+#include "xptcprivate.h"
+
+// 8 integral parameters are passed in registers
+#define GPR_COUNT     8
+
+// 8 floating point parameters are passed in registers, floats are
+// promoted to doubles when passed in registers
+#define FPR_COUNT     8
+
+extern "C" uint32_t
+invoke_count_words(uint32_t paramCount, nsXPTCVariant* s)
+{
+  return uint32_t(((paramCount * 2) + 3) & ~3);
+}
+
+extern "C" void
+invoke_copy_to_stack(uint32_t* d,
+                     uint32_t paramCount,
+                     nsXPTCVariant* s, 
+                     uint32_t* gpregs,
+                     double* fpregs)
+{
+    uint32_t gpr = 1; // skip one GP reg for 'that'
+    uint32_t fpr = 0;
+    uint32_t tempu32;
+    uint64_t tempu64;
+    
+    for(uint32_t i = 0; i < paramCount; i++, s++) {
+        if(s->IsPtrData()) {
+            if(s->type == nsXPTType::T_JSVAL)
+               tempu32 = (uint32_t) &(s->ptr);
+            else
+               tempu32 = (uint32_t) s->ptr;
+        } else {
+            switch(s->type) {
+            case nsXPTType::T_FLOAT:                                  break;
+            case nsXPTType::T_DOUBLE:                                 break;
+            case nsXPTType::T_I8:     tempu32 = s->val.i8;            break;
+            case nsXPTType::T_I16:    tempu32 = s->val.i16;           break;
+            case nsXPTType::T_I32:    tempu32 = s->val.i32;           break;
+            case nsXPTType::T_I64:    tempu64 = s->val.i64;           break;
+            case nsXPTType::T_U8:     tempu32 = s->val.u8;            break;
+            case nsXPTType::T_U16:    tempu32 = s->val.u16;           break;
+            case nsXPTType::T_U32:    tempu32 = s->val.u32;           break;
+            case nsXPTType::T_U64:    tempu64 = s->val.u64;           break;
+            case nsXPTType::T_BOOL:   tempu32 = s->val.b;             break;
+            case nsXPTType::T_CHAR:   tempu32 = s->val.c;             break;
+            case nsXPTType::T_WCHAR:  tempu32 = s->val.wc;            break;
+            default:                  tempu32 = (uint32_t) s->val.p;  break;
+            }
+        }
+
+        if (!s->IsPtrData() && s->type == nsXPTType::T_DOUBLE) {
+            if (fpr < FPR_COUNT)
+                fpregs[fpr++]    = s->val.d;
+            else {
+                if ((uint32_t) d & 4) d++; // doubles are 8-byte aligned on stack
+                *((double*) d) = s->val.d;
+                d += 2;
+		if (gpr < GPR_COUNT)
+		    gpr += 2;
+            }
+        }
+        else if (!s->IsPtrData() && s->type == nsXPTType::T_FLOAT) {
+            if (fpr < FPR_COUNT)
+                fpregs[fpr++]   = s->val.f; // if passed in registers, floats are promoted to doubles
+            else {
+                *((float*) d) = s->val.f;
+		d += 1;
+		if (gpr < GPR_COUNT)
+		    gpr += 1;
+	    }
+        }
+        else if (!s->IsPtrData() && (s->type == nsXPTType::T_I64
+                                     || s->type == nsXPTType::T_U64)) {
+            if ((gpr + 1) < GPR_COUNT) {
+                if (gpr & 1) gpr++; // longlongs are aligned in odd/even register pairs, eg. r5/r6
+                *((uint64_t*) &gpregs[gpr]) = tempu64;
+                gpr += 2;
+            }
+            else {
+                if ((uint32_t) d & 4) d++; // longlongs are 8-byte aligned on stack
+                *((uint64_t*) d)            = tempu64;
+                d += 2;
+            }
+        }
+        else {
+            if (gpr < GPR_COUNT)
+                gpregs[gpr++] = tempu32;
+            else
+                *d++          = tempu32;
+        }
+        
+    }
+}
+
+extern "C"
+XPTC_PUBLIC_API(nsresult)
+XPTC_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                   uint32_t paramCount, nsXPTCVariant* params);
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc_openbsd.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc_openbsd.cpp
new file mode 100644
index 000000000..5353220fe
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc_openbsd.cpp
@@ -0,0 +1,109 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Platform specific code to invoke XPCOM methods on native objects
+
+// The purpose of NS_InvokeByIndex() is to map a platform
+// indepenpent call to the platform ABI. To do that,
+// NS_InvokeByIndex() has to determine the method to call via vtable
+// access. The parameters for the method are read from the
+// nsXPTCVariant* and prepared for th native ABI.  For the Linux/PPC
+// ABI this means that the first 8 integral and floating point
+// parameters are passed in registers.
+
+#include "xptcprivate.h"
+
+// 8 integral parameters are passed in registers
+#define GPR_COUNT     8
+
+// 8 floating point parameters are passed in registers, floats are
+// promoted to doubles when passed in registers
+#define FPR_COUNT     8
+
+extern "C" uint32_t
+invoke_count_words(uint32_t paramCount, nsXPTCVariant* s)
+{
+  return uint32_t(((paramCount * 2) + 3) & ~3);
+}
+
+extern "C" void
+invoke_copy_to_stack(uint32_t* d,
+                     uint32_t paramCount,
+                     nsXPTCVariant* s, 
+                     uint32_t* gpregs,
+                     double* fpregs)
+{
+    uint32_t gpr = 1; // skip one GP reg for 'that'
+    uint32_t fpr = 0;
+    uint32_t tempu32;
+    uint64_t tempu64;
+    
+    for(uint32_t i = 0; i < paramCount; i++, s++) {
+        if(s->IsPtrData()) {
+            if(s->type == nsXPTType::T_JSVAL)
+               tempu32 = (uint32_t) &(s->ptr);
+            else
+               tempu32 = (uint32_t) s->ptr;
+        } else {
+            switch(s->type) {
+            case nsXPTType::T_FLOAT:                                  break;
+            case nsXPTType::T_DOUBLE:                                 break;
+            case nsXPTType::T_I8:     tempu32 = s->val.i8;            break;
+            case nsXPTType::T_I16:    tempu32 = s->val.i16;           break;
+            case nsXPTType::T_I32:    tempu32 = s->val.i32;           break;
+            case nsXPTType::T_I64:    tempu64 = s->val.i64;           break;
+            case nsXPTType::T_U8:     tempu32 = s->val.u8;            break;
+            case nsXPTType::T_U16:    tempu32 = s->val.u16;           break;
+            case nsXPTType::T_U32:    tempu32 = s->val.u32;           break;
+            case nsXPTType::T_U64:    tempu64 = s->val.u64;           break;
+            case nsXPTType::T_BOOL:   tempu32 = s->val.b;             break;
+            case nsXPTType::T_CHAR:   tempu32 = s->val.c;             break;
+            case nsXPTType::T_WCHAR:  tempu32 = s->val.wc;            break;
+            default:                  tempu32 = (uint32_t) s->val.p;  break;
+            }
+        }
+
+        if (!s->IsPtrData() && s->type == nsXPTType::T_DOUBLE) {
+            if (fpr < FPR_COUNT)
+                fpregs[fpr++]    = s->val.d;
+            else {
+                if ((uint32_t) d & 4) d++; // doubles are 8-byte aligned on stack
+                *((double*) d) = s->val.d;
+                d += 2;
+            }
+        }
+        else if (!s->IsPtrData() && s->type == nsXPTType::T_FLOAT) {
+            if (fpr < FPR_COUNT)
+                fpregs[fpr++]   = s->val.f; // if passed in registers, floats are promoted to doubles
+            else
+                *((float*) d++) = s->val.f;
+        }
+        else if (!s->IsPtrData() && (s->type == nsXPTType::T_I64
+                                     || s->type == nsXPTType::T_U64)) {
+            if ((gpr + 1) < GPR_COUNT) {
+                if (gpr & 1) gpr++; // longlongs are aligned in odd/even register pairs, eg. r5/r6
+                *((uint64_t*) &gpregs[gpr]) = tempu64;
+                gpr += 2;
+            }
+            else {
+                if ((uint32_t) d & 4) d++; // longlongs are 8-byte aligned on stack
+                *((uint64_t*) d)            = tempu64;
+                d += 2;
+            }
+        }
+        else {
+            if (gpr < GPR_COUNT)
+                gpregs[gpr++] = tempu32;
+            else
+                *d++          = tempu32;
+        }
+        
+    }
+}
+
+extern "C"
+EXPORT_XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                 uint32_t paramCount, nsXPTCVariant* params);
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc_rhapsody.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc_rhapsody.cpp
new file mode 100644
index 000000000..1a40cfeea
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_ppc_rhapsody.cpp
@@ -0,0 +1,113 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+extern "C" uint32_t
+invoke_count_words(uint32_t paramCount, nsXPTCVariant* s)
+{
+    uint32_t result = 0;
+    /*    fprintf(stderr,"invoke_count_words(%d,%p)\n",paramCount, s);*/
+
+    for(uint32_t i = 0; i < paramCount; i++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            result++;
+            continue;
+        }
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     :
+        case nsXPTType::T_I16    :
+        case nsXPTType::T_I32    :
+            result++;
+            break;
+        case nsXPTType::T_I64    :
+            result+=2;
+            break;
+        case nsXPTType::T_U8     :
+        case nsXPTType::T_U16    :
+        case nsXPTType::T_U32    :
+            result++;
+            break;
+        case nsXPTType::T_U64    :
+            result+=2;
+            break;
+        case nsXPTType::T_FLOAT  :
+            result++;
+            break;
+        case nsXPTType::T_DOUBLE :
+            result+=2;
+            break;
+        case nsXPTType::T_BOOL   :
+        case nsXPTType::T_CHAR   :
+        case nsXPTType::T_WCHAR  :
+            result++;
+            break;
+        default:
+            // all the others are plain pointer types
+            result++;
+            break;
+        }
+    }
+    return result;
+}
+
+extern "C" void
+invoke_copy_to_stack(uint32_t* d, uint32_t paramCount, nsXPTCVariant* s, double *fprData)
+{
+	uint32_t fpCount = 0;
+
+    /*    fprintf(stderr,"invoke_copy_to_stack(%p, %d, %p, %p)\n", d, paramCount, s, fprData);*/
+
+    for(uint32_t i = 0; i < paramCount; i++, d++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            *((void**)d) = s->ptr;
+            continue;
+        }
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     : *((int32_t*) d) = s->val.i8;          break;
+        case nsXPTType::T_I16    : *((int32_t*) d) = s->val.i16;         break;
+        case nsXPTType::T_I32    : *((int32_t*) d) = s->val.i32;         break;
+        case nsXPTType::T_I64    : *((int64_t*) d) = s->val.i64; d++;    break;
+        case nsXPTType::T_U8     : *((uint32_t*) d) = s->val.u8;          break;
+        case nsXPTType::T_U16    : *((uint32_t*)d) = s->val.u16;         break;
+        case nsXPTType::T_U32    : *((uint32_t*)d) = s->val.u32;         break;
+        case nsXPTType::T_U64    : *((uint64_t*)d) = s->val.u64; d++;    break;
+        case nsXPTType::T_FLOAT  : *((float*)   d) = s->val.f;
+        			   if (fpCount < 13)
+        		               fprData[fpCount++] = s->val.f;
+        			   break;
+        case nsXPTType::T_DOUBLE : *((double*)  d) = s->val.d;   d++;
+        			   if (fpCount < 13)
+        			       fprData[fpCount++] = s->val.d;
+        			   break;
+        case nsXPTType::T_BOOL   : *((uint32_t*) d) = s->val.b;          break;
+        case nsXPTType::T_CHAR   : *((int32_t*)  d) = s->val.c;          break;
+        case nsXPTType::T_WCHAR  : *((uint32_t*) d) = s->val.wc;         break;
+        default:
+            // all the others are plain pointer types
+            *((void**)d) = s->val.p;
+            break;
+        }
+    }
+}
+
+extern "C" nsresult _NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                                      uint32_t paramCount, 
+                                      nsXPTCVariant* params);
+
+EXPORT_XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                 uint32_t paramCount, nsXPTCVariant* params)
+{
+    return _NS_InvokeByIndex(that, methodIndex, paramCount, params);
+}    
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_sparc64_openbsd.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_sparc64_openbsd.cpp
new file mode 100644
index 000000000..050f9414d
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_sparc64_openbsd.cpp
@@ -0,0 +1,69 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+#if !defined(__sparc) && !defined(__sparc__)
+#error "This code is for Sparc only"
+#endif
+
+extern "C" uint64_t
+invoke_copy_to_stack(uint64_t* d, uint32_t paramCount, nsXPTCVariant* s)
+{
+  /*
+    We need to copy the parameters for this function to locals and use them
+    from there since the parameters occupy the same stack space as the stack
+    we're trying to populate.
+  */
+  uint64_t *l_d = d;
+  nsXPTCVariant *l_s = s;
+  uint64_t l_paramCount = paramCount;
+  uint64_t regCount = 0;  // return the number of registers to load from the stack
+
+  for(uint64_t i = 0; i < l_paramCount; i++, l_d++, l_s++)
+  {
+    if (regCount < 5) regCount++;
+
+    if (l_s->IsPtrData())
+    {
+      *l_d = (uint64_t)l_s->ptr;
+      continue;
+    }
+    switch (l_s->type)
+    {
+      case nsXPTType::T_I8    : *((int64_t*)l_d)     = l_s->val.i8;    break;
+      case nsXPTType::T_I16   : *((int64_t*)l_d)     = l_s->val.i16;   break;
+      case nsXPTType::T_I32   : *((int64_t*)l_d)     = l_s->val.i32;   break;
+      case nsXPTType::T_I64   : *((int64_t*)l_d)     = l_s->val.i64;   break;
+      
+      case nsXPTType::T_U8    : *((uint64_t*)l_d)    = l_s->val.u8;    break;
+      case nsXPTType::T_U16   : *((uint64_t*)l_d)    = l_s->val.u16;   break;
+      case nsXPTType::T_U32   : *((uint64_t*)l_d)    = l_s->val.u32;   break;
+      case nsXPTType::T_U64   : *((uint64_t*)l_d)    = l_s->val.u64;   break;
+
+      /* in the case of floats, we want to put the bits in to the
+         64bit space right justified... floats in the parameter array on
+         sparcv9 use odd numbered registers.. %f1, %f3, so we have to skip
+         the space that would be occupied by %f0, %f2, etc.
+      */
+      case nsXPTType::T_FLOAT : *(((float*)l_d) + 1) = l_s->val.f;     break;
+      case nsXPTType::T_DOUBLE: *((double*)l_d)      = l_s->val.d;     break;
+      case nsXPTType::T_BOOL  : *((int64_t*)l_d)     = l_s->val.b;     break;
+      case nsXPTType::T_CHAR  : *((uint64_t*)l_d)    = l_s->val.c;     break;
+      case nsXPTType::T_WCHAR : *((int64_t*)l_d)     = l_s->val.wc;    break;
+
+      default:
+        // all the others are plain pointer types
+        *((void**)l_d) = l_s->val.p;
+        break;
+    }
+  }
+  
+  return regCount;
+}
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_sparc_netbsd.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_sparc_netbsd.cpp
new file mode 100644
index 000000000..126ef1dad
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_sparc_netbsd.cpp
@@ -0,0 +1,131 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+/* solaris defines __sparc for workshop compilers and 
+   linux defines __sparc__ */
+
+#if !defined(__sparc) && !defined(__sparc__)
+#error "This code is for Sparc only"
+#endif
+
+typedef unsigned nsXPCVariant;
+
+extern "C" uint32_t
+invoke_count_words(uint32_t paramCount, nsXPTCVariant* s)
+{
+    uint32_t result = 0;
+    for(uint32_t i = 0; i < paramCount; i++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            result++;
+            continue;
+        }
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     :
+        case nsXPTType::T_I16    :
+        case nsXPTType::T_I32    :
+            result++;
+            break;
+        case nsXPTType::T_I64    :
+            result+=2;
+            break;
+        case nsXPTType::T_U8     :
+        case nsXPTType::T_U16    :
+        case nsXPTType::T_U32    :
+            result++;
+            break;
+        case nsXPTType::T_U64    :
+            result+=2;
+            break;
+        case nsXPTType::T_FLOAT  :
+            result++;
+            break;
+        case nsXPTType::T_DOUBLE :
+            result+=2;
+            break;
+        case nsXPTType::T_BOOL   :
+        case nsXPTType::T_CHAR   :
+        case nsXPTType::T_WCHAR  :
+            result++;
+            break;
+        default:
+            // all the others are plain pointer types
+            result++;
+            break;
+        }
+    }
+    // nuts, I know there's a cooler way of doing this, but it's late
+    // now and it'll probably come to me in the morning.
+    if (result & 0x3) result += 4 - (result & 0x3);     // ensure q-word alignment
+    return result;
+}
+
+extern "C" uint32_t
+invoke_copy_to_stack(uint32_t* d, uint32_t paramCount, nsXPTCVariant* s)
+{
+/*
+    We need to copy the parameters for this function to locals and use them
+    from there since the parameters occupy the same stack space as the stack
+    we're trying to populate.
+*/
+    uint32_t *l_d = d;
+    nsXPTCVariant *l_s = s;
+    uint32_t l_paramCount = paramCount;
+    uint32_t regCount = 0;	// return the number of registers to load from the stack
+
+    typedef struct {
+        uint32_t hi;
+        uint32_t lo;
+    } DU;               // have to move 64 bit entities as 32 bit halves since
+                        // stack slots are not guaranteed 16 byte aligned
+
+    for(uint32_t i = 0; i < l_paramCount; i++, l_d++, l_s++)
+    {
+	if (regCount < 5) regCount++;
+        if(l_s->IsPtrData())
+        {
+            if(l_s->type == nsXPTType::T_JSVAL)
+            {
+              // On SPARC, we need to pass a pointer to HandleValue
+              *((void**)l_d) = &l_s->ptr;
+            } else
+            {
+              *((void**)l_d) = l_s->ptr;
+            }
+            continue;
+        }
+        switch(l_s->type)
+        {
+        case nsXPTType::T_I8     : *((int32_t*)   l_d) = l_s->val.i8;          break;
+        case nsXPTType::T_I16    : *((int32_t*)  l_d) = l_s->val.i16;         break;
+        case nsXPTType::T_I32    : *((int32_t*)  l_d) = l_s->val.i32;         break;
+        case nsXPTType::T_I64    : 
+        case nsXPTType::T_U64    : 
+        case nsXPTType::T_DOUBLE : *((uint32_t*) l_d++) = ((DU *)l_s)->hi;
+				   if (regCount < 5) regCount++;
+                                   *((uint32_t*) l_d) = ((DU *)l_s)->lo;
+                                   break;
+        case nsXPTType::T_U8     : *((uint32_t*) l_d) = l_s->val.u8;          break;
+        case nsXPTType::T_U16    : *((uint32_t*) l_d) = l_s->val.u16;         break;
+        case nsXPTType::T_U32    : *((uint32_t*) l_d) = l_s->val.u32;         break;
+        case nsXPTType::T_FLOAT  : *((float*)  l_d) = l_s->val.f;           break;
+        case nsXPTType::T_BOOL   : *((uint32_t*) l_d) = l_s->val.b;           break;
+        case nsXPTType::T_CHAR   : *((uint32_t*) l_d) = l_s->val.c;           break;
+        case nsXPTType::T_WCHAR  : *((int32_t*)  l_d) = l_s->val.wc;          break;
+        default:
+            // all the others are plain pointer types
+            *((void**)l_d) = l_s->val.p;
+            break;
+        }
+    }
+    return regCount;
+}
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_sparc_openbsd.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_sparc_openbsd.cpp
new file mode 100644
index 000000000..9b2e4f858
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_sparc_openbsd.cpp
@@ -0,0 +1,128 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+#if !defined(__sparc__)
+#error "This code is for Sparc only"
+#endif
+
+typedef unsigned nsXPCVariant;
+
+extern "C" uint32_t
+invoke_count_words(uint32_t paramCount, nsXPTCVariant* s)
+{
+    uint32_t result = 0;
+    for(uint32_t i = 0; i < paramCount; i++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            result++;
+            continue;
+        }
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     :
+        case nsXPTType::T_I16    :
+        case nsXPTType::T_I32    :
+            result++;
+            break;
+        case nsXPTType::T_I64    :
+            result+=2;
+            break;
+        case nsXPTType::T_U8     :
+        case nsXPTType::T_U16    :
+        case nsXPTType::T_U32    :
+            result++;
+            break;
+        case nsXPTType::T_U64    :
+            result+=2;
+            break;
+        case nsXPTType::T_FLOAT  :
+            result++;
+            break;
+        case nsXPTType::T_DOUBLE :
+            result+=2;
+            break;
+        case nsXPTType::T_BOOL   :
+        case nsXPTType::T_CHAR   :
+        case nsXPTType::T_WCHAR  :
+            result++;
+            break;
+        default:
+            // all the others are plain pointer types
+            result++;
+            break;
+        }
+    }
+    // nuts, I know there's a cooler way of doing this, but it's late
+    // now and it'll probably come to me in the morning.
+    if (result & 0x3) result += 4 - (result & 0x3);     // ensure q-word alignment
+    return result;
+}
+
+extern "C" uint32_t
+invoke_copy_to_stack(uint32_t* d, uint32_t paramCount, nsXPTCVariant* s)
+{
+/*
+    We need to copy the parameters for this function to locals and use them
+    from there since the parameters occupy the same stack space as the stack
+    we're trying to populate.
+*/
+    uint32_t *l_d = d;
+    nsXPTCVariant *l_s = s;
+    uint32_t l_paramCount = paramCount;
+    uint32_t regCount = 0;	// return the number of registers to load from the stack
+
+    typedef struct {
+        uint32_t hi;
+        uint32_t lo;
+    } DU;               // have to move 64 bit entities as 32 bit halves since
+                        // stack slots are not guaranteed 16 byte aligned
+
+    for(uint32_t i = 0; i < l_paramCount; i++, l_d++, l_s++)
+    {
+	if (regCount < 5) regCount++;
+        if(l_s->IsPtrData())
+        {
+            if(l_s->type == nsXPTType::T_JSVAL)
+            {
+              // On SPARC, we need to pass a pointer to HandleValue
+              *((void**)l_d) = &l_s->ptr;
+            } else
+            {
+              *((void**)l_d) = l_s->ptr;
+            }
+            continue;
+        }
+        switch(l_s->type)
+        {
+        case nsXPTType::T_I8     : *((int32_t*)  l_d) = l_s->val.i8;          break;
+        case nsXPTType::T_I16    : *((int32_t*)  l_d) = l_s->val.i16;         break;
+        case nsXPTType::T_I32    : *((int32_t*)  l_d) = l_s->val.i32;         break;
+        case nsXPTType::T_I64    : 
+        case nsXPTType::T_U64    : 
+        case nsXPTType::T_DOUBLE : *((uint32_t*) l_d++) = ((DU *)l_s)->hi;
+				   if (regCount < 5) regCount++;
+                                   *((uint32_t*) l_d) = ((DU *)l_s)->lo;
+                                   break;
+        case nsXPTType::T_U8     : *((uint32_t*) l_d) = l_s->val.u8;          break;
+        case nsXPTType::T_U16    : *((uint32_t*) l_d) = l_s->val.u16;         break;
+        case nsXPTType::T_U32    : *((uint32_t*) l_d) = l_s->val.u32;         break;
+        case nsXPTType::T_FLOAT  : *((float*)  l_d) = l_s->val.f;           break;
+        case nsXPTType::T_BOOL   : *((uint32_t*) l_d) = l_s->val.b;           break;
+        case nsXPTType::T_CHAR   : *((uint32_t*) l_d) = l_s->val.c;           break;
+        case nsXPTType::T_WCHAR  : *((int32_t*)  l_d) = l_s->val.wc;          break;
+        default:
+            // all the others are plain pointer types
+            *((void**)l_d) = l_s->val.p;
+            break;
+        }
+    }
+    return regCount;
+}
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_sparc_solaris.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_sparc_solaris.cpp
new file mode 100644
index 000000000..126ef1dad
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_sparc_solaris.cpp
@@ -0,0 +1,131 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+/* solaris defines __sparc for workshop compilers and 
+   linux defines __sparc__ */
+
+#if !defined(__sparc) && !defined(__sparc__)
+#error "This code is for Sparc only"
+#endif
+
+typedef unsigned nsXPCVariant;
+
+extern "C" uint32_t
+invoke_count_words(uint32_t paramCount, nsXPTCVariant* s)
+{
+    uint32_t result = 0;
+    for(uint32_t i = 0; i < paramCount; i++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            result++;
+            continue;
+        }
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     :
+        case nsXPTType::T_I16    :
+        case nsXPTType::T_I32    :
+            result++;
+            break;
+        case nsXPTType::T_I64    :
+            result+=2;
+            break;
+        case nsXPTType::T_U8     :
+        case nsXPTType::T_U16    :
+        case nsXPTType::T_U32    :
+            result++;
+            break;
+        case nsXPTType::T_U64    :
+            result+=2;
+            break;
+        case nsXPTType::T_FLOAT  :
+            result++;
+            break;
+        case nsXPTType::T_DOUBLE :
+            result+=2;
+            break;
+        case nsXPTType::T_BOOL   :
+        case nsXPTType::T_CHAR   :
+        case nsXPTType::T_WCHAR  :
+            result++;
+            break;
+        default:
+            // all the others are plain pointer types
+            result++;
+            break;
+        }
+    }
+    // nuts, I know there's a cooler way of doing this, but it's late
+    // now and it'll probably come to me in the morning.
+    if (result & 0x3) result += 4 - (result & 0x3);     // ensure q-word alignment
+    return result;
+}
+
+extern "C" uint32_t
+invoke_copy_to_stack(uint32_t* d, uint32_t paramCount, nsXPTCVariant* s)
+{
+/*
+    We need to copy the parameters for this function to locals and use them
+    from there since the parameters occupy the same stack space as the stack
+    we're trying to populate.
+*/
+    uint32_t *l_d = d;
+    nsXPTCVariant *l_s = s;
+    uint32_t l_paramCount = paramCount;
+    uint32_t regCount = 0;	// return the number of registers to load from the stack
+
+    typedef struct {
+        uint32_t hi;
+        uint32_t lo;
+    } DU;               // have to move 64 bit entities as 32 bit halves since
+                        // stack slots are not guaranteed 16 byte aligned
+
+    for(uint32_t i = 0; i < l_paramCount; i++, l_d++, l_s++)
+    {
+	if (regCount < 5) regCount++;
+        if(l_s->IsPtrData())
+        {
+            if(l_s->type == nsXPTType::T_JSVAL)
+            {
+              // On SPARC, we need to pass a pointer to HandleValue
+              *((void**)l_d) = &l_s->ptr;
+            } else
+            {
+              *((void**)l_d) = l_s->ptr;
+            }
+            continue;
+        }
+        switch(l_s->type)
+        {
+        case nsXPTType::T_I8     : *((int32_t*)   l_d) = l_s->val.i8;          break;
+        case nsXPTType::T_I16    : *((int32_t*)  l_d) = l_s->val.i16;         break;
+        case nsXPTType::T_I32    : *((int32_t*)  l_d) = l_s->val.i32;         break;
+        case nsXPTType::T_I64    : 
+        case nsXPTType::T_U64    : 
+        case nsXPTType::T_DOUBLE : *((uint32_t*) l_d++) = ((DU *)l_s)->hi;
+				   if (regCount < 5) regCount++;
+                                   *((uint32_t*) l_d) = ((DU *)l_s)->lo;
+                                   break;
+        case nsXPTType::T_U8     : *((uint32_t*) l_d) = l_s->val.u8;          break;
+        case nsXPTType::T_U16    : *((uint32_t*) l_d) = l_s->val.u16;         break;
+        case nsXPTType::T_U32    : *((uint32_t*) l_d) = l_s->val.u32;         break;
+        case nsXPTType::T_FLOAT  : *((float*)  l_d) = l_s->val.f;           break;
+        case nsXPTType::T_BOOL   : *((uint32_t*) l_d) = l_s->val.b;           break;
+        case nsXPTType::T_CHAR   : *((uint32_t*) l_d) = l_s->val.c;           break;
+        case nsXPTType::T_WCHAR  : *((int32_t*)  l_d) = l_s->val.wc;          break;
+        default:
+            // all the others are plain pointer types
+            *((void**)l_d) = l_s->val.p;
+            break;
+        }
+    }
+    return regCount;
+}
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_sparcv9_solaris.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_sparcv9_solaris.cpp
new file mode 100644
index 000000000..0d2d6b0a8
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_sparcv9_solaris.cpp
@@ -0,0 +1,73 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+#if !defined(__sparc) && !defined(__sparc__)
+#error "This code is for Sparc only"
+#endif
+
+/* Prototype specifies unmangled function name */
+extern "C" uint64_t
+invoke_copy_to_stack(uint64_t* d, uint32_t paramCount, nsXPTCVariant* s);
+
+extern "C" uint64_t
+invoke_copy_to_stack(uint64_t* d, uint32_t paramCount, nsXPTCVariant* s)
+{
+  /*
+    We need to copy the parameters for this function to locals and use them
+    from there since the parameters occupy the same stack space as the stack
+    we're trying to populate.
+  */
+  uint64_t *l_d = d;
+  nsXPTCVariant *l_s = s;
+  uint64_t l_paramCount = paramCount;
+  uint64_t regCount = 0;  // return the number of registers to load from the stack
+
+  for(uint64_t i = 0; i < l_paramCount; i++, l_d++, l_s++)
+  {
+    if (regCount < 5) regCount++;
+
+    if (l_s->IsPtrData())
+    {
+      *l_d = (uint64_t)l_s->ptr;
+      continue;
+    }
+    switch (l_s->type)
+    {
+      case nsXPTType::T_I8    : *((int64_t*)l_d)     = l_s->val.i8;    break;
+      case nsXPTType::T_I16   : *((int64_t*)l_d)     = l_s->val.i16;   break;
+      case nsXPTType::T_I32   : *((int64_t*)l_d)     = l_s->val.i32;   break;
+      case nsXPTType::T_I64   : *((int64_t*)l_d)     = l_s->val.i64;   break;
+      
+      case nsXPTType::T_U8    : *((uint64_t*)l_d)    = l_s->val.u8;    break;
+      case nsXPTType::T_U16   : *((uint64_t*)l_d)    = l_s->val.u16;   break;
+      case nsXPTType::T_U32   : *((uint64_t*)l_d)    = l_s->val.u32;   break;
+      case nsXPTType::T_U64   : *((uint64_t*)l_d)    = l_s->val.u64;   break;
+
+      /* in the case of floats, we want to put the bits in to the
+         64bit space right justified... floats in the parameter array on
+         sparcv9 use odd numbered registers.. %f1, %f3, so we have to skip
+         the space that would be occupied by %f0, %f2, etc.
+      */
+      case nsXPTType::T_FLOAT : *(((float*)l_d) + 1) = l_s->val.f;     break;
+      case nsXPTType::T_DOUBLE: *((double*)l_d)      = l_s->val.d;     break;
+      case nsXPTType::T_BOOL  : *((uint64_t*)l_d)    = l_s->val.b;     break;
+      case nsXPTType::T_CHAR  : *((uint64_t*)l_d)    = l_s->val.c;     break;
+      case nsXPTType::T_WCHAR : *((int64_t*)l_d)     = l_s->val.wc;    break;
+
+      default:
+        // all the others are plain pointer types
+        *((void**)l_d) = l_s->val.p;
+        break;
+    }
+  }
+  
+  return regCount;
+}
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_x86_64_solaris.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_x86_64_solaris.cpp
new file mode 100644
index 000000000..0d3424366
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_x86_64_solaris.cpp
@@ -0,0 +1,149 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Platform specific code to invoke XPCOM methods on native objects
+
+#include "xptcprivate.h"
+#include "alloca.h"
+
+// 6 integral parameters are passed in registers
+const uint32_t GPR_COUNT = 6;
+
+// 8 floating point parameters are passed in SSE registers
+const uint32_t FPR_COUNT = 8;
+
+// Remember that these 'words' are 64-bit long
+static inline void
+invoke_count_words(uint32_t paramCount, nsXPTCVariant * s,
+                   uint32_t & nr_gpr, uint32_t & nr_fpr, uint32_t & nr_stack)
+{
+    nr_gpr = 1; // skip one GP register for 'that'
+    nr_fpr = 0;
+    nr_stack = 0;
+
+    /* Compute number of eightbytes of class MEMORY.  */
+    for (uint32_t i = 0; i < paramCount; i++, s++) {
+        if (!s->IsPtrData()
+            && (s->type == nsXPTType::T_FLOAT || s->type == nsXPTType::T_DOUBLE)) {
+            if (nr_fpr < FPR_COUNT)
+                nr_fpr++;
+            else
+                nr_stack++;
+        }
+        else {
+            if (nr_gpr < GPR_COUNT)
+                nr_gpr++;
+            else
+                nr_stack++;
+        }
+    }
+}
+
+static void
+invoke_copy_to_stack(uint64_t * d, uint32_t paramCount, nsXPTCVariant * s,
+                     uint64_t * gpregs, double * fpregs)
+{
+    uint32_t nr_gpr = 1; // skip one GP register for 'that'
+    uint32_t nr_fpr = 0;
+    uint64_t value;
+
+    for (uint32_t i = 0; i < paramCount; i++, s++) {
+        if (s->IsPtrData())
+            value = (uint64_t) s->ptr;
+        else {
+            switch (s->type) {
+            case nsXPTType::T_FLOAT:                                break;
+            case nsXPTType::T_DOUBLE:                               break;
+            case nsXPTType::T_I8:     value = s->val.i8;            break;
+            case nsXPTType::T_I16:    value = s->val.i16;           break;
+            case nsXPTType::T_I32:    value = s->val.i32;           break;
+            case nsXPTType::T_I64:    value = s->val.i64;           break;
+            case nsXPTType::T_U8:     value = s->val.u8;            break;
+            case nsXPTType::T_U16:    value = s->val.u16;           break;
+            case nsXPTType::T_U32:    value = s->val.u32;           break;
+            case nsXPTType::T_U64:    value = s->val.u64;           break;
+            case nsXPTType::T_BOOL:   value = s->val.b;             break;
+            case nsXPTType::T_CHAR:   value = s->val.c;             break;
+            case nsXPTType::T_WCHAR:  value = s->val.wc;            break;
+            default:                  value = (uint64_t) s->val.p;  break;
+            }
+        }
+
+        if (!s->IsPtrData() && s->type == nsXPTType::T_DOUBLE) {
+            if (nr_fpr < FPR_COUNT)
+                fpregs[nr_fpr++] = s->val.d;
+            else {
+                *((double *)d) = s->val.d;
+                d++;
+            }
+        }
+        else if (!s->IsPtrData() && s->type == nsXPTType::T_FLOAT) {
+            if (nr_fpr < FPR_COUNT)
+                // The value in %xmm register is already prepared to
+                // be retrieved as a float. Therefore, we pass the
+                // value verbatim, as a double without conversion.
+                fpregs[nr_fpr++] = s->val.d;
+            else {
+                *((float *)d) = s->val.f;
+                d++;
+            }
+        }
+        else {
+            if (nr_gpr < GPR_COUNT)
+                gpregs[nr_gpr++] = value;
+            else
+                *d++ = value;
+        }
+    }
+}
+
+// Avoid AddressSanitizer instrumentation for the next function because it
+// depends on __builtin_alloca behavior and alignment that cannot be relied on
+// once the function is compiled with a version of ASan that has dynamic-alloca
+// instrumentation enabled.
+
+MOZ_ASAN_BLACKLIST
+EXPORT_XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports * that, uint32_t methodIndex,
+                 uint32_t paramCount, nsXPTCVariant * params)
+{
+    uint32_t nr_gpr, nr_fpr, nr_stack;
+    invoke_count_words(paramCount, params, nr_gpr, nr_fpr, nr_stack);
+    
+    // Stack, if used, must be 16-bytes aligned
+    if (nr_stack)
+        nr_stack = (nr_stack + 1) & ~1;
+
+    // Load parameters to stack, if necessary
+    uint64_t *stack = (uint64_t *) __builtin_alloca(nr_stack * 8);
+    uint64_t gpregs[GPR_COUNT];
+    double fpregs[FPR_COUNT];
+    invoke_copy_to_stack(stack, paramCount, params, gpregs, fpregs);
+
+    switch (nr_fpr) {
+      case 8: asm("movupd %0, %xmm7" : : "xmm7" (fpregs[7]));
+      case 7: asm("movupd %0, %xmm6" : : "xmm6" (fpregs[6]));
+      case 6: asm("movupd %0, %xmm5" : : "xmm5" (fpregs[5]));
+      case 5: asm("movupd %0, %xmm4" : : "xmm4" (fpregs[4]));
+      case 4: asm("movupd %0, %xmm3" : : "xmm3" (fpregs[3]));
+      case 3: asm("movupd %0, %xmm2" : : "xmm2" (fpregs[2]));
+      case 2: asm("movupd %0, %xmm1" : : "xmm1" (fpregs[1]));
+      case 1: asm("movupd %0, %xmm0" : : "xmm0" (fpregs[0]));
+      case 0:;
+    }
+    
+    // Ensure that assignments to SSE registers won't be optimized away
+    asm("" ::: "xmm0", "xmm1", "xmm2", "xmm3", "xmm4", "xmm5", "xmm6", "xmm7");
+    
+    // Get pointer to method
+    uint64_t methodAddress = *((uint64_t *)that);
+    methodAddress += 16 + 8 * methodIndex;
+    methodAddress = *((uint64_t *)methodAddress);
+    
+    typedef uint32_t (*Method)(uint64_t, uint64_t, uint64_t, uint64_t, uint64_t, uint64_t);
+    uint32_t result = ((Method)methodAddress)((uint64_t)that, gpregs[1], gpregs[2], gpregs[3], gpregs[4], gpregs[5]);
+    return result;
+}
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_x86_64_unix.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_x86_64_unix.cpp
new file mode 100644
index 000000000..08e519889
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_x86_64_unix.cpp
@@ -0,0 +1,188 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Platform specific code to invoke XPCOM methods on native objects
+
+#include "xptcprivate.h"
+
+// 6 integral parameters are passed in registers
+const uint32_t GPR_COUNT = 6;
+
+// 8 floating point parameters are passed in SSE registers
+const uint32_t FPR_COUNT = 8;
+
+// Remember that these 'words' are 64-bit long
+static inline void
+invoke_count_words(uint32_t paramCount, nsXPTCVariant * s,
+                   uint32_t & nr_stack)
+{
+    uint32_t nr_gpr;
+    uint32_t nr_fpr;
+    nr_gpr = 1; // skip one GP register for 'that'
+    nr_fpr = 0;
+    nr_stack = 0;
+
+    /* Compute number of eightbytes of class MEMORY.  */
+    for (uint32_t i = 0; i < paramCount; i++, s++) {
+        if (!s->IsPtrData()
+            && (s->type == nsXPTType::T_FLOAT || s->type == nsXPTType::T_DOUBLE)) {
+            if (nr_fpr < FPR_COUNT)
+                nr_fpr++;
+            else
+                nr_stack++;
+        }
+        else {
+            if (nr_gpr < GPR_COUNT)
+                nr_gpr++;
+            else
+                nr_stack++;
+        }
+    }
+}
+
+static void
+invoke_copy_to_stack(uint64_t * d, uint32_t paramCount, nsXPTCVariant * s,
+                     uint64_t * gpregs, double * fpregs)
+{
+    uint32_t nr_gpr = 1u; // skip one GP register for 'that'
+    uint32_t nr_fpr = 0u;
+    uint64_t value = 0u;
+
+    for (uint32_t i = 0; i < paramCount; i++, s++) {
+        if (s->IsPtrData())
+            value = (uint64_t) s->ptr;
+        else {
+            switch (s->type) {
+            case nsXPTType::T_FLOAT:                                break;
+            case nsXPTType::T_DOUBLE:                               break;
+            case nsXPTType::T_I8:     value = s->val.i8;            break;
+            case nsXPTType::T_I16:    value = s->val.i16;           break;
+            case nsXPTType::T_I32:    value = s->val.i32;           break;
+            case nsXPTType::T_I64:    value = s->val.i64;           break;
+            case nsXPTType::T_U8:     value = s->val.u8;            break;
+            case nsXPTType::T_U16:    value = s->val.u16;           break;
+            case nsXPTType::T_U32:    value = s->val.u32;           break;
+            case nsXPTType::T_U64:    value = s->val.u64;           break;
+            case nsXPTType::T_BOOL:   value = s->val.b;             break;
+            case nsXPTType::T_CHAR:   value = s->val.c;             break;
+            case nsXPTType::T_WCHAR:  value = s->val.wc;            break;
+            default:                  value = (uint64_t) s->val.p;  break;
+            }
+        }
+
+        if (!s->IsPtrData() && s->type == nsXPTType::T_DOUBLE) {
+            if (nr_fpr < FPR_COUNT)
+                fpregs[nr_fpr++] = s->val.d;
+            else {
+                *((double *)d) = s->val.d;
+                d++;
+            }
+        }
+        else if (!s->IsPtrData() && s->type == nsXPTType::T_FLOAT) {
+            if (nr_fpr < FPR_COUNT)
+                // The value in %xmm register is already prepared to
+                // be retrieved as a float. Therefore, we pass the
+                // value verbatim, as a double without conversion.
+                fpregs[nr_fpr++] = s->val.d;
+            else {
+                *((float *)d) = s->val.f;
+                d++;
+            }
+        }
+        else {
+            if (nr_gpr < GPR_COUNT)
+                gpregs[nr_gpr++] = value;
+            else
+                *d++ = value;
+        }
+    }
+}
+
+// Disable avx for the next function to allow compilation with
+// -march=native on new machines, or similar hardcoded -march options.
+// Having avx enabled appears to change the alignment behavior of alloca
+// (apparently adding an extra 16 bytes) of padding/alignment (and using
+// 32-byte alignment instead of 16-byte).  This seems to be the best
+// available workaround, given that this code, which should perhaps
+// better be written in assembly, is written in C++.
+#ifndef __clang__
+#pragma GCC push_options
+#pragma GCC target ("no-avx")
+#endif
+
+// Avoid AddressSanitizer instrumentation for the next function because it
+// depends on __builtin_alloca behavior and alignment that cannot be relied on
+// once the function is compiled with a version of ASan that has dynamic-alloca
+// instrumentation enabled.
+
+MOZ_ASAN_BLACKLIST
+EXPORT_XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports * that, uint32_t methodIndex,
+                 uint32_t paramCount, nsXPTCVariant * params)
+{
+    uint32_t nr_stack;
+    invoke_count_words(paramCount, params, nr_stack);
+    
+    // Stack, if used, must be 16-bytes aligned
+    if (nr_stack)
+        nr_stack = (nr_stack + 1) & ~1;
+
+    // Load parameters to stack, if necessary
+    uint64_t *stack = (uint64_t *) __builtin_alloca(nr_stack * 8);
+    uint64_t gpregs[GPR_COUNT];
+    double fpregs[FPR_COUNT];
+    invoke_copy_to_stack(stack, paramCount, params, gpregs, fpregs);
+
+    // We used to have switches to make sure we would only load the registers
+    // that are needed for this call. That produced larger code that was
+    // not faster in practice. It also caused compiler warnings about the
+    // variables being used uninitialized.
+    // We now just load every every register. There could still be a warning
+    // from a memory analysis tools that we are loading uninitialized stack
+    // positions.
+
+    // FIXME: this function depends on the above __builtin_alloca placing
+    // the array in the correct spot for the ABI.
+
+    // Load FPR registers from fpregs[]
+    double d0, d1, d2, d3, d4, d5, d6, d7;
+
+    d7 = fpregs[7];
+    d6 = fpregs[6];
+    d5 = fpregs[5];
+    d4 = fpregs[4];
+    d3 = fpregs[3];
+    d2 = fpregs[2];
+    d1 = fpregs[1];
+    d0 = fpregs[0];
+
+    // Load GPR registers from gpregs[]
+    uint64_t a0, a1, a2, a3, a4, a5;
+
+    a5 = gpregs[5];
+    a4 = gpregs[4];
+    a3 = gpregs[3];
+    a2 = gpregs[2];
+    a1 = gpregs[1];
+    a0 = (uint64_t) that;
+
+    // Get pointer to method
+    uint64_t methodAddress = *((uint64_t *)that);
+    methodAddress += 8 * methodIndex;
+    methodAddress = *((uint64_t *)methodAddress);
+    
+    typedef nsresult (*Method)(uint64_t, uint64_t, uint64_t, uint64_t,
+                               uint64_t, uint64_t, double, double, double,
+                               double, double, double, double, double);
+    nsresult result = ((Method)methodAddress)(a0, a1, a2, a3, a4, a5,
+                                              d0, d1, d2, d3, d4, d5,
+                                              d6, d7);
+    return result;
+}
+
+#ifndef __clang__
+#pragma GCC pop_options
+#endif
diff --git a/xpcom/reflect/xptcall/md/unix/xptcinvoke_x86_solaris.cpp b/xpcom/reflect/xptcall/md/unix/xptcinvoke_x86_solaris.cpp
new file mode 100644
index 000000000..f545fcc99
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcinvoke_x86_solaris.cpp
@@ -0,0 +1,67 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+extern "C" {
+
+// Remember that these 'words' are 32bit DWORDS
+
+uint32_t
+invoke_count_words(uint32_t paramCount, nsXPTCVariant* s)
+{
+    uint32_t result = 0;
+    for(uint32_t i = 0; i < paramCount; i++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            result++;
+            continue;
+        }
+        result++;
+        switch(s->type)
+        {
+        case nsXPTType::T_I64    :
+        case nsXPTType::T_U64    :
+        case nsXPTType::T_DOUBLE :
+            result++;
+            break;
+        }
+    }
+    return result;
+}
+
+void
+invoke_copy_to_stack(uint32_t paramCount, nsXPTCVariant* s, uint32_t* d)
+{
+    for(uint32_t i = 0; i < paramCount; i++, d++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            *((void**)d) = s->ptr;
+            continue;
+        }
+
+/* XXX: the following line is here (rather than as the default clause in
+ *      the following switch statement) so that the Sun native compiler
+ *      will generate the correct assembly code on the Solaris Intel
+ *      platform. See the comments in bug #28817 for more details.
+ */
+
+        *((void**)d) = s->val.p;
+
+        switch(s->type)
+        {
+        case nsXPTType::T_I64    : *((int64_t*) d) = s->val.i64; d++;    break;
+        case nsXPTType::T_U64    : *((uint64_t*)d) = s->val.u64; d++;    break;
+        case nsXPTType::T_DOUBLE : *((double*)  d) = s->val.d;   d++;    break;
+        }
+    }
+}
+
+}
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_aarch64.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_aarch64.cpp
new file mode 100644
index 000000000..571fb42a2
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_aarch64.cpp
@@ -0,0 +1,219 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+#ifndef __AARCH64EL__
+#error "Only little endian compatibility was tested"
+#endif
+
+/*
+ * This is for AArch64 ABI
+ *
+ * When we're called, the "gp" registers are stored in gprData and
+ * the "fp" registers are stored in fprData. Each array has 8 regs
+ * but first reg in gprData is a placeholder for 'self'.
+ */
+extern "C" nsresult
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint64_t* args,
+                   uint64_t *gprData, double *fprData)
+{
+#define PARAM_BUFFER_COUNT        16
+#define PARAM_GPR_COUNT            8
+#define PARAM_FPR_COUNT            8
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = NULL;
+    const nsXPTMethodInfo* info;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no method info");
+
+    uint32_t paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if (paramCount > PARAM_BUFFER_COUNT) {
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    } else {
+        dispatchParams = paramBuffer;
+    }
+    NS_ASSERTION(dispatchParams,"no place for params");
+
+    uint64_t* ap = args;
+    uint32_t next_gpr = 1; // skip first arg which is 'self'
+    uint32_t next_fpr = 0;
+    for (uint32_t i = 0; i < paramCount; i++) {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if (param.IsOut() || !type.IsArithmetic()) {
+            if (next_gpr < PARAM_GPR_COUNT) {
+                dp->val.p = (void*)gprData[next_gpr++];
+            } else {
+                dp->val.p = (void*)*ap++;
+            }
+            continue;
+        }
+
+        switch (type) {
+            case nsXPTType::T_I8:
+                if (next_gpr < PARAM_GPR_COUNT) {
+                    dp->val.i8  = (int8_t)gprData[next_gpr++];
+                } else {
+                    dp->val.i8  = (int8_t)*ap++;
+                }
+                break;
+
+            case nsXPTType::T_I16:
+                if (next_gpr < PARAM_GPR_COUNT) {
+                    dp->val.i16  = (int16_t)gprData[next_gpr++];
+                } else {
+                    dp->val.i16  = (int16_t)*ap++;
+                }
+                break;
+
+            case nsXPTType::T_I32:
+                if (next_gpr < PARAM_GPR_COUNT) {
+                    dp->val.i32  = (int32_t)gprData[next_gpr++];
+                } else {
+                    dp->val.i32  = (int32_t)*ap++;
+                }
+                break;
+
+            case nsXPTType::T_I64:
+                if (next_gpr < PARAM_GPR_COUNT) {
+                    dp->val.i64  = (int64_t)gprData[next_gpr++];
+                } else {
+                    dp->val.i64  = (int64_t)*ap++;
+                }
+                break;
+
+            case nsXPTType::T_U8:
+                if (next_gpr < PARAM_GPR_COUNT) {
+                    dp->val.u8  = (uint8_t)gprData[next_gpr++];
+                } else {
+                    dp->val.u8  = (uint8_t)*ap++;
+                }
+                break;
+
+            case nsXPTType::T_U16:
+                if (next_gpr < PARAM_GPR_COUNT) {
+                    dp->val.u16  = (uint16_t)gprData[next_gpr++];
+                } else {
+                    dp->val.u16  = (uint16_t)*ap++;
+                }
+                break;
+
+            case nsXPTType::T_U32:
+                if (next_gpr < PARAM_GPR_COUNT) {
+                    dp->val.u32  = (uint32_t)gprData[next_gpr++];
+                } else {
+                    dp->val.u32  = (uint32_t)*ap++;
+                }
+                break;
+
+            case nsXPTType::T_U64:
+                if (next_gpr < PARAM_GPR_COUNT) {
+                    dp->val.u64  = (uint64_t)gprData[next_gpr++];
+                } else {
+                    dp->val.u64  = (uint64_t)*ap++;
+                }
+                break;
+
+            case nsXPTType::T_FLOAT:
+                if (next_fpr < PARAM_FPR_COUNT) {
+                    memcpy(&dp->val.f, &fprData[next_fpr++], sizeof(dp->val.f));
+                } else {
+                    memcpy(&dp->val.f, ap++, sizeof(dp->val.f));
+                }
+                break;
+
+            case nsXPTType::T_DOUBLE:
+                if (next_fpr < PARAM_FPR_COUNT) {
+                    memcpy(&dp->val.d, &fprData[next_fpr++], sizeof(dp->val.d));
+                } else {
+                    memcpy(&dp->val.d, ap++, sizeof(dp->val.d));
+                }
+                break;
+
+            case nsXPTType::T_BOOL:
+                if (next_gpr < PARAM_GPR_COUNT) {
+                    dp->val.b  = (bool)gprData[next_gpr++];
+                } else {
+                    dp->val.b  = (bool)*ap++;
+                }
+                break;
+
+            case nsXPTType::T_CHAR:
+                if (next_gpr < PARAM_GPR_COUNT) {
+                    dp->val.c  = (char)gprData[next_gpr++];
+                } else {
+                    dp->val.c  = (char)*ap++;
+                }
+                break;
+
+            case nsXPTType::T_WCHAR:
+                if (next_gpr < PARAM_GPR_COUNT) {
+                    dp->val.wc  = (wchar_t)gprData[next_gpr++];
+                } else {
+                    dp->val.wc  = (wchar_t)*ap++;
+                }
+                break;
+
+            default:
+                NS_ASSERTION(0, "bad type");
+                break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    if (dispatchParams != paramBuffer) {
+        delete [] dispatchParams;
+    }
+
+    return result;
+}
+
+// Load w17 with the constant 'n' and branch to SharedStub().
+# define STUB_ENTRY(n)                                                  \
+    __asm__ (                                                           \
+            ".section \".text\" \n\t"                                   \
+            ".align 2\n\t"                                              \
+            ".if "#n" < 10 \n\t"                                        \
+            ".globl  _ZN14nsXPTCStubBase5Stub"#n"Ev \n\t"               \
+            ".hidden _ZN14nsXPTCStubBase5Stub"#n"Ev \n\t"               \
+            ".type   _ZN14nsXPTCStubBase5Stub"#n"Ev,@function \n\n"     \
+            "_ZN14nsXPTCStubBase5Stub"#n"Ev: \n\t"                      \
+            ".elseif "#n" < 100 \n\t"                                   \
+            ".globl  _ZN14nsXPTCStubBase6Stub"#n"Ev \n\t"               \
+            ".hidden _ZN14nsXPTCStubBase6Stub"#n"Ev \n\t"               \
+            ".type   _ZN14nsXPTCStubBase6Stub"#n"Ev,@function \n\n"     \
+            "_ZN14nsXPTCStubBase6Stub"#n"Ev: \n\t"                      \
+            ".elseif "#n" < 1000 \n\t"                                  \
+            ".globl  _ZN14nsXPTCStubBase7Stub"#n"Ev \n\t"               \
+            ".hidden _ZN14nsXPTCStubBase7Stub"#n"Ev \n\t"               \
+            ".type   _ZN14nsXPTCStubBase7Stub"#n"Ev,@function \n\n"     \
+            "_ZN14nsXPTCStubBase7Stub"#n"Ev: \n\t"                      \
+            ".else  \n\t"                                               \
+            ".err   \"stub number "#n" >= 1000 not yet supported\"\n"   \
+            ".endif \n\t"                                               \
+            "mov    w17,#"#n" \n\t"                                     \
+            "b      SharedStub \n"                                      \
+);
+
+#define SENTINEL_ENTRY(n)                              \
+    nsresult nsXPTCStubBase::Sentinel##n()             \
+{                                                      \
+    NS_ASSERTION(0,"nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED;                   \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_alpha_openbsd.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_alpha_openbsd.cpp
new file mode 100644
index 000000000..d538767e1
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_alpha_openbsd.cpp
@@ -0,0 +1,189 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+/* Prototype specifies unmangled function name and disables unused warning */
+static nsresult
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint64_t* args)
+__asm__("PrepareAndDispatch") ATTRIBUTE_USED;
+
+static nsresult
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint64_t* args)
+{
+    const uint8_t PARAM_BUFFER_COUNT = 16;
+    const uint8_t NUM_ARG_REGS = 6-1;        // -1 for "this" pointer
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+
+    NS_ASSERTION(dispatchParams,"no place for params");
+    if (!dispatchParams)
+        return NS_ERROR_OUT_OF_MEMORY;
+
+    // args[0] to args[NUM_ARG_REGS] hold floating point register values
+    uint64_t* ap = args + NUM_ARG_REGS;
+    for(i = 0; i < paramCount; i++, ap++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            dp->val.p = (void*) *ap;
+            continue;
+        }
+        // else
+        switch(type)
+        {
+        case nsXPTType::T_I8     : dp->val.i8  = (int8_t)    *ap;    break;
+        case nsXPTType::T_I16    : dp->val.i16 = (int16_t)   *ap;    break;
+        case nsXPTType::T_I32    : dp->val.i32 = (int32_t)   *ap;    break;
+        case nsXPTType::T_I64    : dp->val.i64 = (int64_t)   *ap;    break;
+        case nsXPTType::T_U8     : dp->val.u8  = (uint8_t)   *ap;    break;
+        case nsXPTType::T_U16    : dp->val.u16 = (uint16_t)  *ap;    break;
+        case nsXPTType::T_U32    : dp->val.u32 = (uint32_t)  *ap;    break;
+        case nsXPTType::T_U64    : dp->val.u64 = (uint64_t)  *ap;    break;
+        case nsXPTType::T_FLOAT  :
+            if(i < NUM_ARG_REGS)
+            {
+                // floats passed via registers are stored as doubles
+                // in the first NUM_ARG_REGS entries in args
+                dp->val.u64 = (uint64_t) args[i];
+                dp->val.f = (float) dp->val.d;    // convert double to float
+            }
+            else
+                dp->val.u32 = (uint32_t) *ap;
+            break;
+        case nsXPTType::T_DOUBLE :
+            // doubles passed via registers are also stored
+            // in the first NUM_ARG_REGS entries in args
+            dp->val.u64 = (i < NUM_ARG_REGS) ? args[i] : *ap;
+            break;
+        case nsXPTType::T_BOOL   : dp->val.b   = (bool)    *ap;    break;
+        case nsXPTType::T_CHAR   : dp->val.c   = (char)      *ap;    break;
+        case nsXPTType::T_WCHAR  : dp->val.wc  = (char16_t) *ap;    break;
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+/*
+ * SharedStub()
+ *  Collects arguments and calls PrepareAndDispatch.  The "methodIndex" is
+ *  passed to this function via $1 to preserve the argument registers.
+ */
+__asm__(
+    "#### SharedStub ####\n"
+".text\n\t"
+    ".align 5\n\t"
+    ".ent SharedStub\n"
+"SharedStub:\n\t"
+    ".frame $30,96,$26,0\n\t"
+    ".mask 0x4000000,-96\n\t"
+    "ldgp $29,0($27)\n"
+"$SharedStub..ng:\n\t"
+    "subq $30,96,$30\n\t"
+    "stq $26,0($30)\n\t"
+    ".prologue 1\n\t"
+
+    /*
+     * Store arguments passed via registers to the stack.
+     * Floating point registers are stored as doubles and converted
+     * to floats in PrepareAndDispatch if necessary.
+     */
+    "stt $f17,16($30)\n\t"   /* floating point registers */
+    "stt $f18,24($30)\n\t"
+    "stt $f19,32($30)\n\t"
+    "stt $f20,40($30)\n\t"
+    "stt $f21,48($30)\n\t"
+    "stq $17,56($30)\n\t"    /* integer registers */
+    "stq $18,64($30)\n\t"
+    "stq $19,72($30)\n\t"
+    "stq $20,80($30)\n\t"
+    "stq $21,88($30)\n\t"
+
+    /*
+     * Call PrepareAndDispatch function.
+     */
+    "bis $1,$1,$17\n\t"      /* pass "methodIndex" */
+    "addq $30,16,$18\n\t"    /* pass "args" */
+    "bsr $26,$PrepareAndDispatch..ng\n\t"
+
+    "ldq $26,0($30)\n\t"
+    "addq $30,96,$30\n\t"
+    "ret $31,($26),1\n\t"
+    ".end SharedStub"
+    );
+
+/*
+ * nsresult nsXPTCStubBase::Stub##n()
+ *  Sets register $1 to "methodIndex" and jumps to SharedStub.
+ */
+#define STUB_MANGLED_ENTRY(n, symbol) \
+    "#### Stub"#n" ####"      "\n\t" \
+    ".text"                   "\n\t" \
+    ".align 5"                "\n\t" \
+    ".globl " symbol          "\n\t" \
+    ".ent " symbol            "\n"   \
+symbol ":"                    "\n\t" \
+    ".frame $30,0,$26,0"      "\n\t" \
+    "ldgp $29,0($27)"         "\n"   \
+"$" symbol "..ng:"            "\n\t" \
+    ".prologue 1"             "\n\t" \
+    "lda $1,"#n               "\n\t" \
+    "br $31,$SharedStub..ng"  "\n\t" \
+    ".end " symbol
+
+#define STUB_ENTRY(n) \
+__asm__( \
+    ".if "#n" < 10"                                              "\n\t" \
+        STUB_MANGLED_ENTRY(n, "_ZN14nsXPTCStubBase5Stub"#n"Ev")  "\n\t" \
+    ".elseif "#n" < 100"                                         "\n\t" \
+        STUB_MANGLED_ENTRY(n, "_ZN14nsXPTCStubBase6Stub"#n"Ev")  "\n\t" \
+    ".elseif "#n" < 1000"                                        "\n\t" \
+        STUB_MANGLED_ENTRY(n, "_ZN14nsXPTCStubBase7Stub"#n"Ev")  "\n\t" \
+    ".else"                                                      "\n\t" \
+    ".err \"Stub"#n" >= 1000 not yet supported.\""               "\n\t" \
+    ".endif" \
+    );
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_arm.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_arm.cpp
new file mode 100644
index 000000000..ef4f8514d
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_arm.cpp
@@ -0,0 +1,238 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+#if !defined(__arm__) && !(defined(LINUX) || defined(ANDROID) || defined(XP_DARWIN))
+#error "This code is for Linux/iOS ARM only. Please check if it works for you, too.\nDepends strongly on gcc behaviour."
+#endif
+
+/* Specify explicitly a symbol for this function, don't try to guess the c++ mangled symbol.  */
+static nsresult PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint32_t* args) asm("_PrepareAndDispatch")
+ATTRIBUTE_USED;
+
+#ifdef __ARM_EABI__
+#define DOUBLEWORD_ALIGN(p) ((uint32_t *)((((uint32_t)(p)) + 7) & 0xfffffff8))
+#else
+#define DOUBLEWORD_ALIGN(p) (p)
+#endif
+
+// Apple's iOS toolchain is lame.
+#ifdef __APPLE__
+#define GNU(str)
+#define APPLE(str) str
+#define UNDERSCORE "__"
+#else
+#define GNU(str) str
+#define APPLE(str)
+#define UNDERSCORE "_"
+#endif
+
+#ifdef __thumb__
+#define THUMB_FUNC ".thumb_func\n"
+#else
+#define THUMB_FUNC
+#endif
+
+static nsresult
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint32_t* args)
+{
+#define PARAM_BUFFER_COUNT     16
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+    NS_ASSERTION(dispatchParams,"no place for params");
+
+    uint32_t* ap = args;
+    for(i = 0; i < paramCount; i++, ap++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            dp->val.p = (void*) *ap;
+            continue;
+        }
+        // else
+        switch(type)
+        {
+        case nsXPTType::T_I8     : dp->val.i8  = *((int8_t*)  ap);       break;
+        case nsXPTType::T_I16    : dp->val.i16 = *((int16_t*) ap);       break;
+        case nsXPTType::T_I32    : dp->val.i32 = *((int32_t*) ap);       break;
+        case nsXPTType::T_I64    : ap = DOUBLEWORD_ALIGN(ap);
+				   dp->val.i64 = *((int64_t*) ap); ap++; break;
+        case nsXPTType::T_U8     : dp->val.u8  = *((uint8_t*) ap);       break;
+        case nsXPTType::T_U16    : dp->val.u16 = *((uint16_t*)ap);       break;
+        case nsXPTType::T_U32    : dp->val.u32 = *((uint32_t*)ap);       break;
+        case nsXPTType::T_U64    : ap = DOUBLEWORD_ALIGN(ap);
+				   dp->val.u64 = *((uint64_t*)ap); ap++; break;
+        case nsXPTType::T_FLOAT  : dp->val.f   = *((float*)   ap);       break;
+        case nsXPTType::T_DOUBLE : ap = DOUBLEWORD_ALIGN(ap);
+				   dp->val.d   = *((double*)  ap); ap++; break;
+        case nsXPTType::T_BOOL   : dp->val.b   = *((bool*)  ap);       break;
+        case nsXPTType::T_CHAR   : dp->val.c   = *((char*)    ap);       break;
+        case nsXPTType::T_WCHAR  : dp->val.wc  = *((wchar_t*) ap);       break;
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+/*
+ * This is our shared stub.
+ *
+ * r0 = Self.
+ *
+ * The Rules:
+ *   We pass an (undefined) number of arguments into this function.
+ *   The first 3 C++ arguments are in r1 - r3, the rest are built
+ *   by the calling function on the stack.
+ *
+ *   We are allowed to corrupt r0 - r3, ip, and lr.
+ *
+ * Other Info:
+ *   We pass the stub number in using `ip'.
+ *
+ * Implementation:
+ * - We save r1 to r3 inclusive onto the stack, which will be
+ *   immediately below the caller saved arguments.
+ * - setup r2 (PrepareAndDispatch's args pointer) to point at
+ *   the base of all these arguments
+ * - Save LR (for the return address)
+ * - Set r1 (PrepareAndDispatch's methodindex argument) from ip
+ * - r0 is passed through (self)
+ * - Call PrepareAndDispatch
+ * - When the call returns, we return by loading the PC off the
+ *   stack, and undoing the stack (one instruction)!
+ *
+ */
+__asm__ ("\n"
+         GNU(".text\n")
+         APPLE(".section __TEXT,__text\n")
+         THUMB_FUNC
+         ".align 2\n"
+         "SharedStub:\n"
+         GNU(".fnstart\n")
+         GNU(".cfi_startproc\n")
+         "stmfd	sp!, {r1, r2, r3}\n"
+         GNU(".save {r1, r2, r3}\n")
+         GNU(".cfi_def_cfa_offset 12\n")
+         GNU(".cfi_offset r3, -4\n")
+         GNU(".cfi_offset r2, -8\n")
+         GNU(".cfi_offset r1, -12\n")
+         "mov	r2, sp\n"
+         "str	lr, [sp, #-4]!\n"
+         GNU(".save	{lr}\n")
+         GNU(".cfi_def_cfa_offset 16\n")
+         GNU(".cfi_offset lr, -16\n")
+         "mov	r1, ip\n"
+         "bl	_PrepareAndDispatch\n"
+         "ldr	pc, [sp], #16\n"
+         GNU(".cfi_endproc\n")
+         GNU(".fnend"));
+
+/*
+ * Create sets of stubs to call the SharedStub.
+ * We don't touch the stack here, nor any registers, other than IP.
+ * IP is defined to be corruptable by a called function, so we are
+ * safe to use it.
+ *
+ * This will work with or without optimisation.
+ */
+
+/*
+ * Note : As G++3 ABI contains the length of the functionname in the
+ *  mangled name, it is difficult to get a generic assembler mechanism like
+ *  in the G++ 2.95 case.
+ *  Create names would be like :
+ *    _ZN14nsXPTCStubBase5Stub9Ev
+ *    _ZN14nsXPTCStubBase6Stub13Ev
+ *    _ZN14nsXPTCStubBase7Stub144Ev
+ *  Use the assembler directives to get the names right...
+ */
+
+#define STUB_ENTRY(n)						\
+  __asm__(							\
+        GNU(".section \".text\"\n")                             \
+        APPLE(".section __TEXT,__text\n")                       \
+"	.align 2\n"						\
+"	.if ("#n" - 10) < 0\n"                                  \
+"	.globl	" UNDERSCORE "ZN14nsXPTCStubBase5Stub"#n"Ev\n"	\
+        THUMB_FUNC                                              \
+        GNU(".type	_ZN14nsXPTCStubBase5Stub"#n"Ev,#function\n") \
+UNDERSCORE "ZN14nsXPTCStubBase5Stub"#n"Ev:\n"			\
+"	.else\n"                                                \
+"	.if  ("#n" - 100) < 0\n"                                \
+"	.globl	" UNDERSCORE "ZN14nsXPTCStubBase6Stub"#n"Ev\n"	\
+          THUMB_FUNC \
+          GNU(".type _ZN14nsXPTCStubBase6Stub"#n"Ev,#function\n") \
+UNDERSCORE "ZN14nsXPTCStubBase6Stub"#n"Ev:\n"			\
+"	.else\n"                                                \
+"	.if ("#n" - 1000) < 0\n"                                \
+"	.globl	" UNDERSCORE "ZN14nsXPTCStubBase7Stub"#n"Ev\n"	\
+        THUMB_FUNC                                              \
+        GNU(".type _ZN14nsXPTCStubBase7Stub"#n"Ev,#function\n") \
+UNDERSCORE "ZN14nsXPTCStubBase7Stub"#n"Ev:\n"			\
+"	.else\n"                                                \
+"	.err \"stub number "#n"> 1000 not yet supported\"\n"    \
+"	.endif\n"                                               \
+"	.endif\n"                                               \
+"	.endif\n"                                               \
+"	mov	ip, #"#n"\n"					\
+"	b	SharedStub\n\t");
+
+#if 0
+/*
+ * This part is left in as comment : this is how the method definition
+ * should look like.
+ */
+
+#define STUB_ENTRY(n)  \
+nsresult nsXPTCStubBase::Stub##n ()  \
+{ \
+  __asm__ (	  		        \
+"	mov	ip, #"#n"\n"					\
+"	b	SharedStub\n\t");                               \
+  return 0; /* avoid warnings */                                \
+}
+#endif
+
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_arm_netbsd.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_arm_netbsd.cpp
new file mode 100644
index 000000000..27c2b3d02
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_arm_netbsd.cpp
@@ -0,0 +1,113 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+
+nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint32_t* args)
+{
+#define PARAM_BUFFER_COUNT     16
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    nsIInterfaceInfo* iface_info = nullptr;
+    const nsXPTMethodInfo* info;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->GetInterfaceInfo(&iface_info);
+    NS_ASSERTION(iface_info,"no interface info");
+
+    iface_info->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no interface info");
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+    NS_ASSERTION(dispatchParams,"no place for params");
+
+    uint32_t* ap = args;
+    for(i = 0; i < paramCount; i++, ap++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            dp->val.p = (void*) *ap;
+            continue;
+        }
+        // else
+        switch(type)
+        {
+        case nsXPTType::T_I8     : dp->val.i8  = *((int8_t*)  ap);       break;
+        case nsXPTType::T_I16    : dp->val.i16 = *((int16_t*) ap);       break;
+        case nsXPTType::T_I32    : dp->val.i32 = *((int32_t*) ap);       break;
+        case nsXPTType::T_I64    : dp->val.i64 = *((int64_t*) ap); ap++; break;
+        case nsXPTType::T_U8     : dp->val.u8  = *((uint8_t*) ap);       break;
+        case nsXPTType::T_U16    : dp->val.u16 = *((uint16_t*)ap);       break;
+        case nsXPTType::T_U32    : dp->val.u32 = *((uint32_t*)ap);       break;
+        case nsXPTType::T_U64    : dp->val.u64 = *((uint64_t*)ap); ap++; break;
+        case nsXPTType::T_FLOAT  : dp->val.f   = *((float*)   ap);       break;
+        case nsXPTType::T_DOUBLE : dp->val.d   = *((double*)  ap); ap++; break;
+        case nsXPTType::T_BOOL   : dp->val.b   = *((bool*)  ap);       break;
+        case nsXPTType::T_CHAR   : dp->val.c   = *((char*)    ap);       break;
+        case nsXPTType::T_WCHAR  : dp->val.wc  = *((wchar_t*) ap);       break;
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    NS_RELEASE(iface_info);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+/*
+ * These stubs move just move the values passed in registers onto the stack,
+ * so they are contiguous with values passed on the stack, and then calls
+ * PrepareAndDispatch() to do the dirty work.
+ */
+
+#define STUB_ENTRY(n)							\
+__asm__(								\
+    ".global	_Stub"#n"__14nsXPTCStubBase\n\t"			\
+"_Stub"#n"__14nsXPTCStubBase:\n\t"					\
+    "stmfd	sp!, {r1, r2, r3}	\n\t"				\
+    "mov	ip, sp			\n\t"				\
+    "stmfd	sp!, {fp, ip, lr, pc}	\n\t"				\
+    "sub	fp, ip, #4		\n\t"				\
+    "mov	r1, #"#n"		\n\t"    /* = methodIndex 	*/ \
+    "add	r2, sp, #16		\n\t"				\
+    "bl		_PrepareAndDispatch__FP14nsXPTCStubBaseUiPUi   \n\t"	\
+    "ldmea	fp, {fp, sp, lr}	\n\t"				\
+    "add	sp, sp, #12		\n\t"				\
+    "mov	pc, lr			\n\t"				\
+);
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_arm_openbsd.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_arm_openbsd.cpp
new file mode 100644
index 000000000..f63d0c1e2
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_arm_openbsd.cpp
@@ -0,0 +1,205 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+#ifdef __GNUC__
+/* This tells gcc3.4+ not to optimize away symbols.
+ * @see http://gcc.gnu.org/gcc-3.4/changes.html
+ */
+#define DONT_DROP_OR_WARN __attribute__((used))
+#else
+/* This tells older gccs not to warn about unused vairables.
+ * @see http://docs.freebsd.org/info/gcc/gcc.info.Variable_Attributes.html
+ */
+#define DONT_DROP_OR_WARN __attribute__((unused))
+#endif
+
+/* Specify explicitly a symbol for this function, don't try to guess the c++ mangled symbol.  */
+static nsresult PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint32_t* args) asm("_PrepareAndDispatch")
+DONT_DROP_OR_WARN;
+
+static nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint32_t* args)
+{
+#define PARAM_BUFFER_COUNT     16
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+
+    NS_ASSERTION(dispatchParams,"no place for params");
+    if (!dispatchParams)
+        return NS_ERROR_OUT_OF_MEMORY;
+
+    uint32_t* ap = args;
+    for(i = 0; i < paramCount; i++, ap++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            dp->val.p = (void*) *ap;
+            continue;
+        }
+        // else
+        switch(type)
+        {
+        case nsXPTType::T_I8     : dp->val.i8  = *((int8_t*)  ap);       break;
+        case nsXPTType::T_I16    : dp->val.i16 = *((int16_t*) ap);       break;
+        case nsXPTType::T_I32    : dp->val.i32 = *((int32_t*) ap);       break;
+        case nsXPTType::T_I64    : dp->val.i64 = *((int64_t*) ap); ap++; break;
+        case nsXPTType::T_U8     : dp->val.u8  = *((uint8_t*) ap);       break;
+        case nsXPTType::T_U16    : dp->val.u16 = *((uint16_t*)ap);       break;
+        case nsXPTType::T_U32    : dp->val.u32 = *((uint32_t*)ap);       break;
+        case nsXPTType::T_U64    : dp->val.u64 = *((uint64_t*)ap); ap++; break;
+        case nsXPTType::T_FLOAT  : dp->val.f   = *((float*)   ap);       break;
+        case nsXPTType::T_DOUBLE : dp->val.d   = *((double*)  ap); ap++; break;
+        case nsXPTType::T_BOOL   : dp->val.b   = *((bool*)  ap);       break;
+        case nsXPTType::T_CHAR   : dp->val.c   = *((char*)    ap);       break;
+        case nsXPTType::T_WCHAR  : dp->val.wc  = *((wchar_t*) ap);       break;
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+/*
+ * This is our shared stub.
+ *
+ * r0 = Self.
+ *
+ * The Rules:
+ *   We pass an (undefined) number of arguments into this function.
+ *   The first 3 C++ arguments are in r1 - r3, the rest are built
+ *   by the calling function on the stack.
+ *
+ *   We are allowed to corrupt r0 - r3, ip, and lr.
+ *
+ * Other Info:
+ *   We pass the stub number in using `ip'.
+ *
+ * Implementation:
+ * - We save r1 to r3 inclusive onto the stack, which will be
+ *   immediately below the caller saved arguments.
+ * - setup r2 (PrepareAndDispatch's args pointer) to point at
+ *   the base of all these arguments
+ * - Save LR (for the return address)
+ * - Set r1 (PrepareAndDispatch's methodindex argument) from ip
+ * - r0 is passed through (self)
+ * - Call PrepareAndDispatch
+ * - When the call returns, we return by loading the PC off the
+ *   stack, and undoing the stack (one instruction)!
+ *
+ */
+__asm__ ("\n\
+        .text							\n\
+        .align 2						\n\
+SharedStub:							\n\
+	stmfd	sp!, {r1, r2, r3}				\n\
+	mov	r2, sp						\n\
+	str	lr, [sp, #-4]!					\n\
+	mov	r1, ip						\n\
+	bl	_PrepareAndDispatch	                        \n\
+	ldr	pc, [sp], #16");
+
+/*
+ * Create sets of stubs to call the SharedStub.
+ * We don't touch the stack here, nor any registers, other than IP.
+ * IP is defined to be corruptable by a called function, so we are
+ * safe to use it.
+ *
+ * This will work with or without optimisation.
+ */
+
+/*
+ * Note : As G++3 ABI contains the length of the functionname in the
+ *  mangled name, it is difficult to get a generic assembler mechanism like
+ *  in the G++ 2.95 case.
+ *  Create names would be like :
+ *    _ZN14nsXPTCStubBase5Stub9Ev
+ *    _ZN14nsXPTCStubBase6Stub13Ev
+ *    _ZN14nsXPTCStubBase7Stub144Ev
+ *  Use the assembler directives to get the names right...
+ */
+
+#define STUB_ENTRY(n)						\
+  __asm__(							\
+	".section \".text\"\n"					\
+"	.align 2\n"						\
+"	.iflt ("#n" - 10)\n"                                    \
+"	.globl	_ZN14nsXPTCStubBase5Stub"#n"Ev\n"		\
+"	.type	_ZN14nsXPTCStubBase5Stub"#n"Ev,#function\n"	\
+"_ZN14nsXPTCStubBase5Stub"#n"Ev:\n"				\
+"	.else\n"                                                \
+"	.iflt  ("#n" - 100)\n"                                  \
+"	.globl	_ZN14nsXPTCStubBase6Stub"#n"Ev\n"		\
+"	.type	_ZN14nsXPTCStubBase6Stub"#n"Ev,#function\n"	\
+"_ZN14nsXPTCStubBase6Stub"#n"Ev:\n"				\
+"	.else\n"                                                \
+"	.iflt ("#n" - 1000)\n"                                  \
+"	.globl	_ZN14nsXPTCStubBase7Stub"#n"Ev\n"		\
+"	.type	_ZN14nsXPTCStubBase7Stub"#n"Ev,#function\n"	\
+"_ZN14nsXPTCStubBase7Stub"#n"Ev:\n"				\
+"	.else\n"                                                \
+"	.err \"stub number "#n"> 1000 not yet supported\"\n"    \
+"	.endif\n"                                               \
+"	.endif\n"                                               \
+"	.endif\n"                                               \
+"	mov	ip, #"#n"\n"					\
+"	b	SharedStub\n\t");
+
+#if 0
+/*
+ * This part is left in as comment : this is how the method definition
+ * should look like.
+ */
+
+#define STUB_ENTRY(n)  \
+nsresult nsXPTCStubBase::Stub##n ()  \
+{ \
+  __asm__ (	  		        \
+"	mov	ip, #"#n"\n"					\
+"	b	SharedStub\n\t");                               \
+  return 0; /* avoid warnings */                                \
+}
+#endif
+
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_aarch64.s b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_aarch64.s
new file mode 100644
index 000000000..6603a4f25
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_aarch64.s
@@ -0,0 +1,39 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+            .set NGPREGS,8
+            .set NFPREGS,8
+
+            .section ".text"
+            .globl SharedStub
+            .hidden SharedStub
+            .type  SharedStub,@function
+SharedStub:
+            stp         x29, x30, [sp,#-16]!
+            mov         x29, sp
+
+            sub         sp, sp, #8*(NGPREGS+NFPREGS)
+            stp         x0, x1, [sp, #64+(0*8)]
+            stp         x2, x3, [sp, #64+(2*8)]
+            stp         x4, x5, [sp, #64+(4*8)]
+            stp         x6, x7, [sp, #64+(6*8)]
+            stp         d0, d1, [sp, #(0*8)]
+            stp         d2, d3, [sp, #(2*8)]
+            stp         d4, d5, [sp, #(4*8)]
+            stp         d6, d7, [sp, #(6*8)]
+
+            # methodIndex passed from stub
+            mov         w1, w17
+
+            add         x2, sp, #16+(8*(NGPREGS+NFPREGS))
+            add         x3, sp, #8*NFPREGS
+            add         x4, sp, #0
+
+            bl          PrepareAndDispatch
+
+            add         sp, sp, #8*(NGPREGS+NFPREGS)
+            ldp         x29, x30, [sp],#16
+            ret
+
+            .size SharedStub, . - SharedStub
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ipf32.s b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ipf32.s
new file mode 100644
index 000000000..720dd6cc7
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ipf32.s
@@ -0,0 +1,123 @@
+
+// Select C numeric constant
+        .radix  C
+        .psr    abi32
+        .psr    msb
+// Section has executable code
+        .section .text, "ax","progbits"
+// procedure named 'SharedStub'
+        .proc   SharedStub
+// manual bundling
+        .explicit
+
+        .global PrepareAndDispatch
+//      .exclass  PrepareAndDispatch, @fullyvisible
+        .type   PrepareAndDispatch,@function
+
+SharedStub::
+// 10 arguments, first 8 are the input arguments of previous
+// function call.  The 9th one is methodIndex and the 10th is the
+// pointer to the remaining input arguments.  The last two arguments
+// are passed in memory.
+        .prologue
+        .save ar.pfs , r41
+// allocate 8 input args, 4 local args, and 5 output args
+        alloc           r41 = ar.pfs, 8, 4, 5, 0   // M
+        .save rp, r40
+        mov             r40 = rp                   // I
+        addp4		out4 = 28, sp           ;; // I
+
+        .save ar.unat, r42
+        mov             r42 = ar.unat              // M
+        .fframe 144
+        add             sp = -144, sp              // A
+// unwind table already knows gp, don't need to specify anything
+        add             r43 = 0, gp             ;; // A
+
+// We have possible 8 integer registers and 8 float registers that could
+// be arguments.  We also have a stack region from the previous
+// stack frame that may hold some stack arguments.
+// We need to write the integer registers to a memory region, write
+// the float registers to a memory region (making sure we don't step
+// on NAT while touching the registers).  We also mark the memory
+// address of the stack arguments.
+// We then call PrepareAndDispatch() specifying the three memory
+// region pointers.
+
+
+        .body
+        add             out0 = 0, in0        // A  move self ptr
+// 144 bytes = 16 byte stack header + 64 byte int space + 64 byte float space
+// methodIndex is at 144 + 16 bytes away from current sp
+// (current frame + previous frame header)
+        ld4             out4 = [out4]        // A  restarg address
+        add             r11  = 160, sp    ;; // A  address of methodIndex
+
+        ld8             out1 = [r11]         // M  load methodIndex
+// sp + 16 is the start of intargs
+        add             out2 = 16, sp        // A  address of intargs
+// the intargs take up 64 bytes, so sp + 16 + 64 is the start of floatargs
+        add             out3 = 80, sp     ;; // A  address of floatargs
+
+        add             r11 = 0, out2     ;; // A
+        st8.spill       [r11] = in1, 8       // M
+        add             r10 = 0, out3     ;; // A
+
+        st8.spill       [r11] = in2, 8    ;; // M
+        st8.spill       [r11] = in3, 8       // M
+        nop.i           0                 ;; // I
+
+        st8.spill       [r11] = in4, 8    ;; // M
+        st8.spill       [r11] = in5, 8       // M
+        nop.i           0                 ;; // I
+
+        st8.spill       [r11] = in6, 8    ;; // M
+        st8.spill       [r11] = in7          // M
+        fclass.nm       p14,p15 = f8,@nat ;; // F
+
+(p14)   stfd            [r10] = f8, 8        // M
+(p15)   add             r10 = 8, r10         // A
+        fclass.nm       p12,p13 = f9,@nat ;; // F
+
+(p12)   stfd            [r10] = f9, 8        // M
+(p13)   add             r10 = 8, r10         // A
+        fclass.nm       p14,p15 =f10,@nat ;; // F
+
+(p14)   stfd            [r10] = f10, 8       // M
+(p15)   add             r10 = 8, r10         // A
+        fclass.nm       p12,p13 =f11,@nat ;; // F
+
+(p12)   stfd            [r10] = f11, 8       // M
+(p13)   add             r10 = 8, r10         // A
+        fclass.nm       p14,p15 =f12,@nat ;; // F
+
+(p14)   stfd            [r10] = f12, 8       // M
+(p15)   add             r10 = 8, r10         // A
+        fclass.nm       p12,p13 =f13,@nat ;; // F
+
+(p12)   stfd            [r10] = f13, 8       // M
+(p13)   add             r10 = 8, r10         // A
+        fclass.nm       p14,p15 =f14,@nat ;; // F
+
+(p14)   stfd            [r10] = f14, 8       // M
+(p15)   add             r10 = 8, r10         // A
+        fclass.nm       p12,p13 =f15,@nat ;; // F
+
+(p12)   stfd            [r10] = f15, 8       // M
+(p13)   add             r10 = 8, r10         // A
+
+// branch to PrepareAndDispatch
+        br.call.dptk.few rp = PrepareAndDispatch ;; // B
+
+// epilog
+        mov             ar.unat = r42        // M
+        mov             ar.pfs = r41         // I
+        mov             rp = r40          ;; // I
+
+        add             gp = 0, r43          // A
+        add             sp = 144, sp         // A
+        br.ret.dptk.few rp                ;; // B
+
+        .endp
+
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ipf64.s b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ipf64.s
new file mode 100644
index 000000000..4c07836d7
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ipf64.s
@@ -0,0 +1,124 @@
+
+// Select C numeric constant
+        .radix  C
+        .psr    abi64
+        .psr    lsb
+// Section has executable code
+        .section .text, "ax","progbits"
+// procedure named 'SharedStub'
+        .proc   SharedStub
+// manual bundling
+        .explicit
+
+        .global PrepareAndDispatch
+//      .exclass  PrepareAndDispatch, @fullyvisible
+        .type   PrepareAndDispatch,@function
+
+SharedStub::
+// 10 arguments, first 8 are the input arguments of previous
+// function call.  The 9th one is methodIndex and the 10th is the
+// pointer to the remaining input arguments.  The last two arguments
+// are passed in memory.
+        .prologue
+        .save ar.pfs , r41
+// allocate 8 input args, 4 local args, and 5 output args
+        alloc           r41 = ar.pfs, 8, 4, 5, 0   // M
+        .save rp, r40
+        mov             r40 = rp                   // I
+        add             out4 = 24, sp           ;; // I
+
+        .save ar.unat, r42
+        mov             r42 = ar.unat              // M
+        .fframe 144
+        add             sp = -144, sp              // A
+// unwind table already knows gp, don't need to specify anything
+        add             r43 = 0, gp             ;; // A
+
+// We have possible 8 integer registers and 8 float registers that could
+// be arguments.  We also have a stack region from the previous
+// stack frame that may hold some stack arguments.
+// We need to write the integer registers to a memory region, write
+// the float registers to a memory region (making sure we don't step
+// on NAT while touching the registers).  We also mark the memory
+// address of the stack arguments.
+// We then call PrepareAndDispatch() specifying the three memory
+// region pointers.
+
+
+        .body
+        add             out0 = 0, in0        // A  move self ptr
+// 144 bytes = 16 byte stack header + 64 byte int space + 64 byte float space
+// methodIndex is at 144 + 16 bytes away from current sp
+// (current frame + previous frame header)
+        ld8             out4 = [out4]        // M  restarg address
+        add             r11  = 160, sp    ;; // A  address of methodIndex
+
+        ld8             out1 = [r11]         // M  load methodIndex
+// sp + 16 is the start of intargs
+        add             out2 = 16, sp        // A  address of intargs
+// the intargs take up 64 bytes, so sp + 16 + 64 is the start of floatargs
+        add             out3 = 80, sp     ;; // A  address of floatargs
+
+        add             r11 = 0, out2     ;; // A
+        st8.spill       [r11] = in1, 8       // M
+        add             r10 = 0, out3     ;; // A
+
+        st8.spill       [r11] = in2, 8    ;; // M
+        st8.spill       [r11] = in3, 8       // M
+        nop.i           0                 ;; // I
+
+        st8.spill       [r11] = in4, 8    ;; // M
+        st8.spill       [r11] = in5, 8       // M
+        nop.i           0                 ;; // I
+
+        st8.spill       [r11] = in6, 8    ;; // M
+        st8.spill       [r11] = in7          // M
+        fclass.nm       p14,p15 = f8,@nat ;; // F
+
+(p14)   stfd            [r10] = f8, 8        // M
+(p15)   add             r10 = 8, r10         // A
+        fclass.nm       p12,p13 = f9,@nat ;; // F
+
+(p12)   stfd            [r10] = f9, 8        // M
+(p13)   add             r10 = 8, r10         // A
+        fclass.nm       p14,p15 =f10,@nat ;; // F
+
+(p14)   stfd            [r10] = f10, 8       // M
+(p15)   add             r10 = 8, r10         // A
+        fclass.nm       p12,p13 =f11,@nat ;; // F
+
+(p12)   stfd            [r10] = f11, 8       // M
+(p13)   add             r10 = 8, r10         // A
+        fclass.nm       p14,p15 =f12,@nat ;; // F
+
+(p14)   stfd            [r10] = f12, 8       // M
+(p15)   add             r10 = 8, r10         // A
+        fclass.nm       p12,p13 =f13,@nat ;; // F
+
+(p12)   stfd            [r10] = f13, 8       // M
+(p13)   add             r10 = 8, r10         // A
+        fclass.nm       p14,p15 =f14,@nat ;; // F
+
+(p14)   stfd            [r10] = f14, 8       // M
+(p15)   add             r10 = 8, r10         // A
+        fclass.nm       p12,p13 =f15,@nat ;; // F
+
+(p12)   stfd            [r10] = f15, 8       // M
+(p13)   add             r10 = 8, r10         // A
+
+// branch to PrepareAndDispatch
+        br.call.dptk.few rp = PrepareAndDispatch ;; // B
+
+// epilog
+        mov             ar.unat = r42        // M
+        mov             ar.pfs = r41         // I
+        mov             rp = r40          ;; // I
+
+        add             gp = 0, r43          // A
+        add             sp = 144, sp         // A
+        br.ret.dptk.few rp                ;; // B
+
+        .endp
+
+/* Magic indicating no need for an executable stack */
+.section .note.GNU-stack, "", @progbits ; .previous
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_mips.S b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_mips.S
new file mode 100644
index 000000000..d17301634
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_mips.S
@@ -0,0 +1,116 @@
+/* -*- Mode: asm; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* This code is for MIPS using the O32 ABI. */
+
+#ifdef ANDROID
+#include <asm/regdef.h>
+#include <asm/asm.h>
+#include <machine/asm.h>
+#else
+#include <sys/regdef.h>
+#include <sys/asm.h>
+#endif
+
+# NARGSAVE is the argument space in the callers frame, including extra
+# 'shadowed' space for the argument registers. The minimum of 4
+# argument slots is sometimes predefined in the header files.
+#ifndef NARGSAVE
+#define NARGSAVE 4
+#endif
+
+#define LOCALSZ 2	/* gp, ra */
+#define FRAMESZ ((((NARGSAVE+LOCALSZ)*SZREG)+ALSZ)&ALMASK)
+
+#define RAOFF (FRAMESZ - (1*SZREG))
+#define GPOFF (FRAMESZ - (2*SZREG))
+
+#define A0OFF (FRAMESZ + (0*SZREG))
+#define A1OFF (FRAMESZ + (1*SZREG))
+#define A2OFF (FRAMESZ + (2*SZREG))
+#define A3OFF (FRAMESZ + (3*SZREG))
+
+	.text
+
+#define STUB_ENTRY(x)						\
+	.if x < 10;						\
+	.globl	_ZN14nsXPTCStubBase5Stub ##x ##Ev;		\
+	.type	_ZN14nsXPTCStubBase5Stub ##x ##Ev,@function;	\
+	.aent	_ZN14nsXPTCStubBase5Stub ##x ##Ev,0;		\
+_ZN14nsXPTCStubBase5Stub ##x ##Ev:;				\
+	SETUP_GP;						\
+	li	t0,x;						\
+	b	sharedstub;					\
+	.elseif x < 100;					\
+	.globl	_ZN14nsXPTCStubBase6Stub ##x ##Ev;		\
+	.type	_ZN14nsXPTCStubBase6Stub ##x ##Ev,@function;	\
+	.aent	_ZN14nsXPTCStubBase6Stub ##x ##Ev,0;		\
+_ZN14nsXPTCStubBase6Stub ##x ##Ev:;				\
+	SETUP_GP;						\
+	li	t0,x;						\
+	b	sharedstub;					\
+	.elseif x < 1000;					\
+	.globl	_ZN14nsXPTCStubBase7Stub ##x ##Ev;		\
+	.type	_ZN14nsXPTCStubBase7Stub ##x ##Ev,@function;	\
+	.aent	_ZN14nsXPTCStubBase7Stub ##x ##Ev,0;		\
+_ZN14nsXPTCStubBase7Stub ##x ##Ev:;				\
+	SETUP_GP;						\
+	li	t0,x;						\
+	b	sharedstub;					\
+	.else;							\
+	.err;							\
+	.endif
+
+# SENTINEL_ENTRY is handled in the cpp file.
+#define SENTINEL_ENTRY(x)
+
+#
+# open a dummy frame for the function entries
+#
+	.align	2
+	.type	dummy,@function
+	.ent	dummy, 0
+	.frame	sp, FRAMESZ, ra 
+dummy:
+	SETUP_GP
+
+#include "xptcstubsdef.inc"
+
+sharedstub:
+	subu	sp, FRAMESZ
+
+	# specify the save register mask for gp, ra, a0-a3
+	.mask 0x900000F0, RAOFF-FRAMESZ
+
+	sw	ra, RAOFF(sp)
+	SAVE_GP(GPOFF)
+
+	# Micro-optimization: a0 is already loaded, and its slot gets
+	# ignored by PrepareAndDispatch, so no need to save it here.
+	# sw	a0, A0OFF(sp)
+	sw	a1, A1OFF(sp)
+	sw	a2, A2OFF(sp)
+	sw	a3, A3OFF(sp)
+
+	la	t9, PrepareAndDispatch
+
+	# t0 is methodIndex
+	move	a1, t0
+	# have a2 point to the begin of the argument space on stack
+	addiu	a2, sp, FRAMESZ
+
+	# PrepareAndDispatch(that, methodIndex, args)
+	jalr	t9
+
+	# Micro-optimization: Using jalr explicitly has the side-effect
+	# of not triggering .cprestore. This is ok because we have no
+	# gp reference below this point. It also allows better
+	# instruction sscheduling.
+	# lw	gp, GPOFF(fp)
+ 
+ 	lw	ra, RAOFF(sp)
+	addiu	sp, FRAMESZ
+	j	ra
+	END(dummy)
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_mips.s.m4 b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_mips.s.m4
new file mode 100644
index 000000000..33c7b1492
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_mips.s.m4
@@ -0,0 +1,75 @@
+/* -*- Mode: asm; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * Version: MPL 1.1
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* This code is for MIPS using the O32 ABI. */
+
+#include <sys/regdef.h>
+#include <sys/asm.h>
+
+	.text
+	.globl PrepareAndDispatch
+
+NARGSAVE=4  # extra space for the callee to use.  gccism
+            # we can put our a0-a3 in our callers space.
+LOCALSZ=2   # gp, ra
+FRAMESZ=(((NARGSAVE+LOCALSZ)*SZREG)+ALSZ)&ALMASK
+
+define(STUB_NAME, `Stub'$1`__14nsXPTCStubBase')
+
+define(STUB_ENTRY,
+`	.globl		'STUB_NAME($1)`
+	.align		2
+	.type		'STUB_NAME($1)`,@function
+	.ent		'STUB_NAME($1)`, 0
+'STUB_NAME($1)`:
+	.frame		sp, FRAMESZ, ra 
+	.set		noreorder
+	.cpload		t9
+	.set		reorder
+	subu		sp, FRAMESZ
+	.cprestore	16	
+	li		t0, '$1`
+	b		sharedstub
+.end			'STUB_NAME($1)`
+
+')
+
+define(SENTINEL_ENTRY, `')
+
+include(xptcstubsdef.inc)
+
+	.globl	sharedstub
+	.ent	sharedstub
+sharedstub:
+
+	REG_S	ra, 20(sp)
+
+	REG_S	a0, 24(sp)
+	REG_S	a1, 28(sp)
+	REG_S	a2, 32(sp)
+	REG_S	a3, 36(sp)
+
+	# t0 is methodIndex
+	move	a1, t0
+
+	# put the start of a1, a2, a3, and stack
+	move	a2, sp
+	addi	a2, 24  # have a2 point to sp + 24 (where a0 is)
+
+	# PrepareAndDispatch(that, methodIndex, args)
+	#                     a0       a1        a2
+	#
+	jal	PrepareAndDispatch
+
+	REG_L	ra, 20(sp)
+	REG_L	a1, 28(sp)
+	REG_L	a2, 32(sp)
+
+	addu	sp, FRAMESZ
+	j	ra
+
+.end sharedstub
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_mips64.S b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_mips64.S
new file mode 100644
index 000000000..11d851536
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_mips64.S
@@ -0,0 +1,111 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include <sys/regdef.h>
+#include <sys/asm.h>
+
+LOCALSZ=16
+FRAMESZ=(((NARGSAVE+LOCALSZ)*SZREG)+ALSZ)&ALMASK
+
+A1OFF=FRAMESZ-(9*SZREG)
+A2OFF=FRAMESZ-(8*SZREG)
+A3OFF=FRAMESZ-(7*SZREG)
+A4OFF=FRAMESZ-(6*SZREG)
+A5OFF=FRAMESZ-(5*SZREG)
+A6OFF=FRAMESZ-(4*SZREG)
+A7OFF=FRAMESZ-(3*SZREG)
+GPOFF=FRAMESZ-(2*SZREG)
+RAOFF=FRAMESZ-(1*SZREG)
+
+F13OFF=FRAMESZ-(16*SZREG)
+F14OFF=FRAMESZ-(15*SZREG)
+F15OFF=FRAMESZ-(14*SZREG)
+F16OFF=FRAMESZ-(13*SZREG)
+F17OFF=FRAMESZ-(12*SZREG)
+F18OFF=FRAMESZ-(11*SZREG)
+F19OFF=FRAMESZ-(10*SZREG)
+
+#define SENTINEL_ENTRY(n)         /* defined in cpp file, not here */
+
+#define STUB_ENTRY(x)                                   \
+    .if x < 10;                                         \
+    MAKE_STUB(x, _ZN14nsXPTCStubBase5Stub ##x ##Ev);    \
+    .elseif x < 100;                                    \
+    MAKE_STUB(x, _ZN14nsXPTCStubBase6Stub ##x ##Ev);    \
+    .elseif x < 1000;                                   \
+    MAKE_STUB(x, _ZN14nsXPTCStubBase7Stub ##x ##Ev);    \
+    .else;                                              \
+    .err;                                               \
+    .endif
+
+#define MAKE_STUB(x, name)                              \
+    .globl   name;                                      \
+    .type    name,@function;                            \
+    .aent    name,0;                                    \
+name:;                                                  \
+    PTR_SUBU sp,FRAMESZ;                                \
+    SETUP_GP64(GPOFF, name);                            \
+    li       t0,x;                                      \
+    b        sharedstub;                                \
+
+#
+# open a dummy frame for the function entries
+#
+    .text
+    .align   2
+    .type    dummy,@function
+    .ent     dummy, 0
+dummy:
+    .frame   sp, FRAMESZ, ra
+    .mask    0x90000FF0, RAOFF-FRAMESZ
+    .fmask   0x000FF000, F19OFF-FRAMESZ
+
+#include "xptcstubsdef.inc"
+
+sharedstub:
+
+    REG_S    a1, A1OFF(sp)
+    REG_S    a2, A2OFF(sp)
+    REG_S    a3, A3OFF(sp)
+    REG_S    a4, A4OFF(sp)
+    REG_S    a5, A5OFF(sp)
+    REG_S    a6, A6OFF(sp)
+    REG_S    a7, A7OFF(sp)
+    REG_S    ra, RAOFF(sp)
+
+    s.d      $f13, F13OFF(sp)
+    s.d      $f14, F14OFF(sp)
+    s.d      $f15, F15OFF(sp)
+    s.d      $f16, F16OFF(sp)
+    s.d      $f17, F17OFF(sp)
+    s.d      $f18, F18OFF(sp)
+    s.d      $f19, F19OFF(sp)
+
+    # t0 is methodIndex
+    move     a1, t0
+
+    # a2 is stack address where extra function params
+    # are stored that do not fit in registers
+    move     a2, sp
+    PTR_ADDI a2, FRAMESZ
+
+    # a3 is stack address of a1..a7
+    move     a3, sp
+    PTR_ADDI a3, A1OFF
+
+    # a4 is stack address of f13..f19
+    move     a4, sp
+    PTR_ADDI a4, F13OFF
+
+    # PrepareAndDispatch(that, methodIndex, args, gprArgs, fpArgs)
+    #                     a0       a1        a2     a3       a4
+    #
+    jal      PrepareAndDispatch
+
+    REG_L    ra, RAOFF(sp)
+    RESTORE_GP64
+
+    PTR_ADDU sp, FRAMESZ
+    j        ra
+    END(dummy)
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_pa32.s b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_pa32.s
new file mode 100644
index 000000000..9e86848fc
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_pa32.s
@@ -0,0 +1,68 @@
+        .LEVEL  1.1
+
+curframesz  .EQU 128
+; SharedStub has stack size of 128 bytes
+
+lastframesz .EQU 64
+; the StubN C++ function has a small stack size of 64 bytes
+
+        .SPACE  $TEXT$,SORT=8
+        .SUBSPA $CODE$,QUAD=0,ALIGN=4,ACCESS=0x2c,CODE_ONLY,SORT=24
+SharedStub
+        .PROC
+        .CALLINFO CALLER,FRAME=80,SAVE_RP,ARGS_SAVED
+
+  .ENTRY
+        STW     %rp,-20(%sp)
+        LDO     128(%sp),%sp
+
+        STW     %r19,-32(%r30)
+        STW     %r26,-36-curframesz(%r30) ; save arg0 in previous frame
+
+        LDO     -80(%r30),%r28
+        FSTD,MA %fr5,8(%r28)   ; save darg0
+        FSTD,MA %fr7,8(%r28)   ; save darg1
+        FSTW,MA %fr4L,4(%r28)  ; save farg0
+        FSTW,MA %fr5L,4(%r28)  ; save farg1
+        FSTW,MA %fr6L,4(%r28)  ; save farg2
+        FSTW,MA %fr7L,4(%r28)  ; save farg3
+
+        ; Former value of register 26 is already properly saved by StubN,
+        ; but register 25-23 are not because of the arguments mismatch
+        STW     %r25,-40-curframesz-lastframesz(%r30) ; save r25
+        STW     %r24,-44-curframesz-lastframesz(%r30) ; save r24
+        STW     %r23,-48-curframesz-lastframesz(%r30) ; save r23
+        COPY    %r26,%r25                             ; method index is arg1
+        LDW     -36-curframesz-lastframesz(%r30),%r26 ; self is arg0
+        LDO     -40-curframesz-lastframesz(%r30),%r24 ; normal args is arg2
+        LDO     -80(%r30),%r23                        ; floating args is arg3
+
+        BL      .+8,%r2
+        ADDIL   L'PrepareAndDispatch-$PIC_pcrel$0+4,%r2
+        LDO     R'PrepareAndDispatch-$PIC_pcrel$1+8(%r1),%r1
+$PIC_pcrel$0
+        LDSID   (%r1),%r31
+$PIC_pcrel$1
+        MTSP    %r31,%sr0
+        .CALL   ARGW0=GR,ARGW1=GR,ARGW2=GR,ARGW3=GR,RTNVAL=GR
+;in=23-26;out=28;
+        BLE     0(%sr0,%r1)
+        COPY    %r31,%r2
+
+        LDW     -32(%r30),%r19
+
+        LDW     -148(%sp),%rp
+        BVE     (%rp)
+  .EXIT
+        LDO     -128(%sp),%sp
+
+
+        .PROCEND        ;in=26;out=28;
+
+  .ALIGN  8
+        .SPACE  $TEXT$
+        .SUBSPA $CODE$
+        .IMPORT PrepareAndDispatch,CODE
+        .EXPORT SharedStub,ENTRY,PRIV_LEV=3,ARGW0=GR,RTNVAL=GR,LONG_RETURN
+        .END
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_parisc_linux.s b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_parisc_linux.s
new file mode 100644
index 000000000..b45d7763b
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_parisc_linux.s
@@ -0,0 +1,73 @@
+/* -*- Mode: asm; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * Version: MPL 1.1
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+  .LEVEL  1.1
+  .TEXT
+  .ALIGN 4
+
+curframesz:
+  .EQU 128
+
+
+; SharedStub has stack size of 128 bytes
+
+lastframesz:
+  .EQU 64
+
+; the StubN C++ function has a small stack size of 64 bytes
+
+
+.globl SharedStub
+  .type SharedStub, @function
+
+SharedStub:
+  .PROC
+  .CALLINFO CALLER,FRAME=80,SAVE_RP
+
+  .ENTRY
+        STW     %rp,-20(%sp)
+        LDO     128(%sp),%sp
+
+        STW     %r19,-32(%r30)
+        STW     %r26,-36-curframesz(%r30) ; save arg0 in previous frame
+
+        LDO     -80(%r30),%r28
+        FSTD,MA %fr5,8(%r28)   ; save darg0
+        FSTD,MA %fr7,8(%r28)   ; save darg1
+        FSTW,MA %fr4L,4(%r28)  ; save farg0
+        FSTW,MA %fr5L,4(%r28)  ; save farg1
+        FSTW,MA %fr6L,4(%r28)  ; save farg2
+        FSTW,MA %fr7L,4(%r28)  ; save farg3
+
+        ; Former value of register 26 is already properly saved by StubN,
+        ; but register 25-23 are not because of the argument mismatch
+        STW     %r25,-40-curframesz-lastframesz(%r30) ; save r25
+        STW     %r24,-44-curframesz-lastframesz(%r30) ; save r24
+        STW     %r23,-48-curframesz-lastframesz(%r30) ; save r23
+        COPY    %r26,%r25                             ; method index is arg1
+        LDW     -36-curframesz-lastframesz(%r30),%r26 ; self is arg0
+        LDO     -40-curframesz-lastframesz(%r30),%r24 ; normal args is arg2
+        LDO     -80(%r30),%r23                        ; floating args is arg3
+
+        .CALL   ARGW0=GR,ARGW1=GR,ARGW2=GR,ARGW3=GR,RTNVAL=GR ;in=23-26;out=28;
+        BL     PrepareAndDispatch, %r31
+        COPY    %r31,%r2
+
+        LDW     -32(%r30),%r19
+
+        LDW     -148(%sp),%rp
+        LDO     -128(%sp),%sp
+
+
+        BV,N     (%rp)
+        NOP
+        NOP
+
+  .EXIT
+  .PROCEND        ;in=26;out=28;
+
+  .SIZE SharedStub, .-SharedStub
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc64_linux.S b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc64_linux.S
new file mode 100644
index 000000000..877e262b9
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc64_linux.S
@@ -0,0 +1,112 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+.set r0,0; .set r1,1; .set RTOC,2; .set r3,3; .set r4,4
+.set r5,5; .set r6,6; .set r7,7; .set r8,8; .set r9,9
+.set r10,10; .set r11,11; .set r12,12; .set r13,13; .set r14,14
+.set r15,15; .set r16,16; .set r17,17; .set r18,18; .set r19,19
+.set r20,20; .set r21,21; .set r22,22; .set r23,23; .set r24,24
+.set r25,25; .set r26,26; .set r27,27; .set r28,28; .set r29,29
+.set r30,30; .set r31,31
+.set f0,0; .set f1,1; .set f2,2; .set f3,3; .set f4,4
+.set f5,5; .set f6,6; .set f7,7; .set f8,8; .set f9,9
+.set f10,10; .set f11,11; .set f12,12; .set f13,13; .set f14,14
+.set f15,15; .set f16,16; .set f17,17; .set f18,18; .set f19,19
+.set f20,20; .set f21,21; .set f22,22; .set f23,23; .set f24,24
+.set f25,25; .set f26,26; .set f27,27; .set f28,28; .set f29,29
+.set f30,30; .set f31,31
+
+#if _CALL_ELF == 2
+#define STACK_PARAMS   96
+#else
+#define STACK_PARAMS   112
+#endif
+
+#if _CALL_ELF == 2
+        .section ".text"
+        .type   SharedStub,@function
+        .globl  SharedStub
+        # Make the symbol hidden so that the branch from the stub does
+        # not go via a PLT.  This is not only better for performance,
+        # but may be necessary to avoid linker errors since there is
+        # no place to restore the TOC register in a sibling call.
+        .hidden SharedStub
+        .align 2
+SharedStub:
+0:      addis 2,12,(.TOC.-0b)@ha
+        addi 2,2,(.TOC.-0b)@l
+        .localentry SharedStub,.-SharedStub
+#else
+        .section ".text"
+        .align 2
+        .globl SharedStub
+        # Make the symbol hidden so that the branch from the stub does
+        # not go via a PLT.  This is not only better for performance,
+        # but may be necessary to avoid linker errors since there is
+        # no place to restore the TOC register in a sibling call.
+        .hidden SharedStub
+        .section ".opd","aw"
+        .align 3
+
+SharedStub:
+        .quad   .SharedStub,.TOC.@tocbase
+        .previous
+        .type   SharedStub,@function
+
+.SharedStub:
+#endif
+        mflr    r0
+
+        std     r4, -56(r1)                     # Save all GPRS
+        std     r5, -48(r1)
+        std     r6, -40(r1)
+        std     r7, -32(r1)
+        std     r8, -24(r1)
+        std     r9, -16(r1)
+        std     r10, -8(r1)
+
+        stfd    f13, -64(r1)                    # ... and FPRS
+        stfd    f12, -72(r1)
+        stfd    f11, -80(r1)
+        stfd    f10, -88(r1)
+        stfd    f9, -96(r1)
+        stfd    f8, -104(r1)
+        stfd    f7, -112(r1)
+        stfd    f6, -120(r1)
+        stfd    f5, -128(r1)
+        stfd    f4, -136(r1)
+        stfd    f3, -144(r1)
+        stfd    f2, -152(r1)
+        stfd    f1, -160(r1)
+
+        subi    r6,r1,56                        # r6 --> gprData
+        subi    r7,r1,160                       # r7 --> fprData
+        addi    r5,r1,STACK_PARAMS              # r5 --> extra stack args
+
+        std     r0, 16(r1)
+	
+        stdu    r1,-288(r1)
+                                                # r3 has the 'self' pointer
+                                                # already
+
+        mr      r4,r11                          # r4 is methodIndex selector,
+                                                # passed via r11 in the
+                                                # nsNSStubBase::StubXX() call
+
+        bl      PrepareAndDispatch
+        nop
+
+        ld      1,0(r1)                         # restore stack
+        ld      r0,16(r1)                       # restore LR
+        mtlr    r0
+        blr
+
+#if _CALL_ELF == 2
+        .size   SharedStub,.-SharedStub
+#else
+        .size   SharedStub,.-.SharedStub
+#endif
+
+        # Magic indicating no need for an executable stack
+        .section .note.GNU-stack, "", @progbits ; .previous
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc_aix.s.m4 b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc_aix.s.m4
new file mode 100644
index 000000000..6dabf334d
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc_aix.s.m4
@@ -0,0 +1,119 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+.set r0,0; .set sp,1; .set RTOC,2; .set r3,3; .set r4,4
+.set r5,5; .set r6,6; .set r7,7; .set r8,8; .set r9,9
+.set r10,10; .set r11,11; .set r12,12; .set r13,13; .set r14,14
+.set r15,15; .set r16,16; .set r17,17; .set r18,18; .set r19,19
+.set r20,20; .set r21,21; .set r22,22; .set r23,23; .set r24,24
+.set r25,25; .set r26,26; .set r27,27; .set r28,28; .set r29,29
+.set r30,30; .set r31,31
+.set f0,0; .set f1,1; .set f2,2; .set f3,3; .set f4,4
+.set f5,5; .set f6,6; .set f7,7; .set f8,8; .set f9,9
+.set f10,10; .set f11,11; .set f12,12; .set f13,13; .set f14,14
+.set f15,15; .set f16,16; .set f17,17; .set f18,18; .set f19,19
+.set f20,20; .set f21,21; .set f22,22; .set f23,23; .set f24,24
+.set f25,25; .set f26,26; .set f27,27; .set f28,28; .set f29,29
+.set f30,30; .set f31,31
+
+# Define the correct name of the stub function based on the object model
+
+define(STUB_NAME, 
+       ifelse(AIX_OBJMODEL, ibm,
+              `Stub'$1`__EI14nsXPTCStubBaseFv',
+              `Stub'$1`__14nsXPTCStubBaseFv'))
+
+define(STUB_ENTRY, `
+    .rename H.10.NO_SYMBOL{PR},""
+    .rename H.18.'STUB_NAME($1)`{TC},"'STUB_NAME($1)`"
+    .csect  H.10.NO_SYMBOL{PR}
+    .globl  .'STUB_NAME($1)`
+    .globl  'STUB_NAME($1)`{DS}
+
+.'STUB_NAME($1)`:
+    li      r12, '$1`
+    b       .SharedStub
+    nop
+        
+
+    .toc
+T.18.'STUB_NAME($1)`:
+    .tc     H.18.'STUB_NAME($1)`{TC},'STUB_NAME($1)`{DS}
+    .csect  'STUB_NAME($1)`{DS}
+    .long   .'STUB_NAME($1)`
+    .long   TOC{TC0}
+    .long   0x00000000
+')
+
+define(SENTINEL_ENTRY, `')
+
+include(xptcstubsdef.inc)
+
+    .rename H.10.NO_SYMBOL{PR},""
+    .rename H.18.SharedStub{TC},"SharedStub"
+
+# .text section
+    .csect  H.10.NO_SYMBOL{PR}
+    .globl  .SharedStub
+    .globl  SharedStub{DS}
+    .extern .PrepareAndDispatch
+
+.SharedStub:
+    mflr    r0
+    stw     r0,8(sp)
+
+    stwu    sp,-176(sp)     # room for linkage (24), fprData (104), gprData(28)
+                            # outgoing params to PrepareAndDispatch (20)
+
+    stw     r4,44(sp)       # link area (24) + PrepareAndDispatch params (20)
+    stw     r5,48(sp)
+    stw     r6,52(sp)
+    stw     r7,56(sp)
+    stw     r8,60(sp)
+    stw     r9,64(sp)
+    stw     r10,68(sp)
+    stfd    f1,72(sp)
+    stfd    f2,80(sp)
+    stfd    f3,88(sp)
+    stfd    f4,96(sp)
+    stfd    f5,104(sp)
+    stfd    f6,112(sp)
+    stfd    f7,120(sp)
+    stfd    f8,128(sp)
+    stfd    f9,136(sp)
+    stfd    f10,144(sp)
+    stfd    f11,152(sp)
+    stfd    f12,156(sp)
+    stfd    f13,164(sp)
+
+    addi    r6,sp,44        # gprData
+
+    addi    r7,sp,72        # fprData
+                            # r3 has the 'self' pointer already
+    mr      r4,r12          # methodIndex selector (it is now LATER)
+    addi    r5,sp,232       # pointer to callers args area, beyond r3-r10
+                            # mapped range
+
+    bl      .PrepareAndDispatch
+    nop
+
+    
+    lwz     r0,184(sp)
+    addi    sp,sp,176
+    mtlr    r0
+    blr
+
+# .data section
+
+    .toc                            # 0x00000038
+T.18.SharedStub:
+    .tc     H.18.SharedStub{TC},SharedStub{DS}
+
+    .csect  SharedStub{DS}
+    .long   .SharedStub             # "\0\0\0\0"
+    .long   TOC{TC0}                # "\0\0\0008"
+    .long   0x00000000              # "\0\0\0\0"
+# End   csect   SharedStub{DS}
+
+# .bss section
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc_aix64.s.m4 b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc_aix64.s.m4
new file mode 100644
index 000000000..24d713cc9
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc_aix64.s.m4
@@ -0,0 +1,97 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+.set r0,0; .set sp,1; .set RTOC,2; .set r3,3; .set r4,4
+.set r5,5; .set r6,6; .set r7,7; .set r8,8; .set r9,9
+.set r10,10; .set r11,11; .set r12,12; .set r13,13; .set r14,14
+.set r15,15; .set r16,16; .set r17,17; .set r18,18; .set r19,19
+.set r20,20; .set r21,21; .set r22,22; .set r23,23; .set r24,24
+.set r25,25; .set r26,26; .set r27,27; .set r28,28; .set r29,29
+.set r30,30; .set r31,31
+.set f0,0; .set f1,1; .set f2,2; .set f3,3; .set f4,4
+.set f5,5; .set f6,6; .set f7,7; .set f8,8; .set f9,9
+.set f10,10; .set f11,11; .set f12,12; .set f13,13; .set f14,14
+.set f15,15; .set f16,16; .set f17,17; .set f18,18; .set f19,19
+.set f20,20; .set f21,21; .set f22,22; .set f23,23; .set f24,24
+.set f25,25; .set f26,26; .set f27,27; .set f28,28; .set f29,29
+.set f30,30; .set f31,31
+# Define the correct name of the stub function based on the object model
+define(STUB_NAME, 
+       ifelse(AIX_OBJMODEL, ibm,
+              `Stub'$1`__EI14nsXPTCStubBaseFv',
+              `Stub'$1`__14nsXPTCStubBaseFv'))
+define(STUB_ENTRY, `
+    .rename H.10.NO_SYMBOL{PR},""
+    .rename H.18.'STUB_NAME($1)`{TC},"'STUB_NAME($1)`"
+    .csect  H.10.NO_SYMBOL{PR}
+    .globl  .'STUB_NAME($1)`
+    .globl  'STUB_NAME($1)`{DS}
+.'STUB_NAME($1)`:
+    li      r12, '$1`
+    b       .SharedStub
+    nop
+    .toc
+T.18.'STUB_NAME($1)`:
+    .tc     H.18.'STUB_NAME($1)`{TC},'STUB_NAME($1)`{DS}
+    .csect  'STUB_NAME($1)`{DS}
+    .llong   .'STUB_NAME($1)`
+    .llong   TOC{TC0}
+    .llong   0x00000000
+')
+define(SENTINEL_ENTRY, `')
+include(xptcstubsdef.inc)
+    .rename H.10.NO_SYMBOL{PR},""
+    .rename H.18.SharedStub{TC},"SharedStub"
+# .text section
+    .csect  H.10.NO_SYMBOL{PR}
+    .globl  .SharedStub
+    .globl  SharedStub{DS}
+    .extern .PrepareAndDispatch
+.SharedStub:
+    mflr    r0
+    std     r0,16(sp)
+    stdu    sp,-248(sp)     # room for linkage (24*2), fprData (104), gprData(28*2)
+                            # outgoing params to PrepareAndDispatch (40)
+    std     r4,88(sp)       # link area (48) + PrepareAndDispatch params (20)
+    std     r5,96(sp)
+    std     r6,104(sp)
+    std     r7,112(sp)
+    std     r8,120(sp)
+    std     r9,128(sp)
+    std     r10,136(sp)
+    stfd    f1,144(sp)
+    stfd    f2,152(sp)
+    stfd    f3,160(sp)
+    stfd    f4,168(sp)
+    stfd    f5,176(sp)
+    stfd    f6,184(sp)
+    stfd    f7,192(sp)
+    stfd    f8,200(sp)
+    stfd    f9,208(sp)
+    stfd    f10,216(sp)
+    stfd    f11,224(sp)
+    stfd    f12,232(sp)
+    stfd    f13,240(sp)
+    addi    r6,sp,88        # gprData
+    addi    r7,sp,144       # fprData
+                            # r3 has the 'self' pointer already
+    mr      r4,r12          # methodIndex selector (it is now LATER)
+    addi    r5,sp,360       # pointer to callers args area, beyond r3-r10
+                            # mapped range
+    bl      .PrepareAndDispatch
+    nop
+    ld      r0,264(sp)
+    addi    sp,sp,248
+    mtlr    r0
+    blr
+# .data section
+    .toc                            # 0x00000038
+T.18.SharedStub:
+    .tc     H.18.SharedStub{TC},SharedStub{DS}
+    .csect  SharedStub{DS}
+    .llong   .SharedStub             # "\0\0\0\0"
+    .llong   TOC{TC0}                # "\0\0\0008"
+    .llong   0x00000000              # "\0\0\0\0"
+# End   csect   SharedStub{DS}
+# .bss section
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc_darwin.s.m4 b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc_darwin.s.m4
new file mode 100644
index 000000000..dda537850
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc_darwin.s.m4
@@ -0,0 +1,114 @@
+/* -*- Mode: asm -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+        .text
+        .globl _SharedStub
+dnl
+define(STUB_MANGLED_ENTRY,
+`        .globl  '$2`
+        .align  2
+'$2`:
+        addi    r12,   0,'$1`
+        b       _SharedStub')
+dnl
+define(STUB_ENTRY,
+`       .if     '$1` < 10
+STUB_MANGLED_ENTRY('$1`, `__ZN14nsXPTCStubBase5Stub'$1`Ev')
+        .elseif '$1` < 100
+STUB_MANGLED_ENTRY('$1`, `__ZN14nsXPTCStubBase6Stub'$1`Ev')
+        .elseif '$1` < 1000
+STUB_MANGLED_ENTRY('$1`, `__ZN14nsXPTCStubBase7Stub'$1`Ev')
+        .else
+        .err    "Stub'$1` >= 1000 not yet supported."
+        .endif
+')
+dnl
+define(SENTINEL_ENTRY, `')
+dnl
+include(xptcstubsdef.inc)
+dnl
+// See also xptcstubs_ppc_rhapsody.cpp:PrepareAndDispatch.
+_SharedStub:
+                                // Prolog(ue)
+        mflr     r0             // Save the link register in the caller's
+        stw      r0,   8(r1)    //   stack frame
+        stwu     r1,-176(r1)    // Allocate stack space for our own frame and
+                                //   adjust stack pointer
+
+                                // Linkage area, 0(r1) to 24(r1)
+                                // Original sp saved at 0(r1)
+
+                                // Parameter area, 20 bytes from 24(r1) to
+                                //   44(r1) to accomodate 5 arguments passed
+                                //   to PrepareAndDispatch
+
+                                // Local variables, 132 bytes from 44(r1)
+                                //   to 176(r1), to accomodate 5 words and
+                                //   13 doubles
+
+        stw      r4,  44(r1)    // Save parameters passed in GPRs r4-r10;
+        stw      r5,  48(r1)    //   a pointer to here will be passed to
+        stw      r6,  52(r1)    //   PrepareAndDispatch for access to
+        stw      r7,  56(r1)    //   arguments passed in registers.  r3,
+        stw      r8,  60(r1)    //   the self pointer, is used for the
+        stw      r9,  64(r1)    //   call but isn't otherwise needed in
+        stw     r10,  68(r1)    //   PrepareAndDispatch, so it is not saved.
+
+        stfd     f1,  72(r1)    // Do the same for floating-point parameters
+        stfd     f2,  80(r1)    //   passed in FPRs f1-f13
+        stfd     f3,  88(r1)
+        stfd     f4,  96(r1)
+        stfd     f5, 104(r1)
+        stfd     f6, 112(r1)
+        stfd     f7, 120(r1)
+        stfd     f8, 128(r1)
+        stfd     f9, 136(r1)
+        stfd    f10, 144(r1)
+        stfd    f11, 152(r1)
+        stfd    f12, 160(r1)
+        stfd    f13, 168(r1)
+
+                                // Set up parameters for call to
+                                //   PrepareAndDispatch.  argument=
+                                // 0, pointer to self, already in r3
+        mr       r4,r12         // 1, stub number
+        addi     r5, r1, 204    // 2, pointer to the parameter area in our
+                                //   caller's stack, for access to
+                                //   parameters beyond those passed in
+                                //   registers.  Skip past the first parameter
+                                //   (corresponding to r3) for the same reason
+                                //   as above.  176 (size of our frame) + 24
+                                //   (size of caller's linkage) + 4 (skipped
+                                //   parameter)
+        addi     r6, r1,  44    // 3, pointer to saved GPRs
+        addi     r7, r1,  72    // 4, pointer to saved FPRs
+
+        bl      L_PrepareAndDispatch$stub
+                                // Do it
+        nop                     // Leave room for linker magic
+
+                                // Epilog(ue)
+        lwz      r0, 184(r1)    // Retrieve old link register value
+        addi     r1, r1, 176    // Restore stack pointer
+        mtlr     r0             // Restore link register
+        blr                     // Return
+
+.picsymbol_stub
+L_PrepareAndDispatch$stub:      // Standard PIC symbol stub
+        .indirect_symbol _PrepareAndDispatch
+        mflr    r0
+        bcl     20,31,L1$pb
+L1$pb:
+        mflr    r11
+        addis   r11,r11,ha16(L1$lz-L1$pb)
+        mtlr    r0
+        lwz     r12,lo16(L1$lz-L1$pb)(r11)
+        mtctr   r12
+        addi    r11,r11,lo16(L1$lz-L1$pb)
+        bctr
+.lazy_symbol_pointer
+L1$lz:
+        .indirect_symbol _PrepareAndDispatch
+        .long   dyld_stub_binding_helper
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc_linux.S b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc_linux.S
new file mode 100644
index 000000000..72a5a9f4b
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc_linux.S
@@ -0,0 +1,77 @@
+// -*- Mode: Asm -*-
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+.set r0,0; .set sp,1; .set RTOC,2; .set r3,3; .set r4,4
+.set r5,5; .set r6,6; .set r7,7; .set r8,8; .set r9,9
+.set r10,10; .set r11,11; .set r12,12; .set r13,13; .set r14,14
+.set r15,15; .set r16,16; .set r17,17; .set r18,18; .set r19,19
+.set r20,20; .set r21,21; .set r22,22; .set r23,23; .set r24,24
+.set r25,25; .set r26,26; .set r27,27; .set r28,28; .set r29,29
+.set r30,30; .set r31,31
+.set f0,0; .set f1,1; .set f2,2; .set f3,3; .set f4,4
+.set f5,5; .set f6,6; .set f7,7; .set f8,8; .set f9,9
+.set f10,10; .set f11,11; .set f12,12; .set f13,13; .set f14,14
+.set f15,15; .set f16,16; .set f17,17; .set f18,18; .set f19,19
+.set f20,20; .set f21,21; .set f22,22; .set f23,23; .set f24,24
+.set f25,25; .set f26,26; .set f27,27; .set f28,28; .set f29,29
+.set f30,30; .set f31,31
+
+        .section ".text"
+        .align 2
+	.globl SharedStub
+	.type  SharedStub,@function
+
+SharedStub:
+        stwu	sp,-112(sp)			// room for 
+						// linkage (8),
+						// gprData (32),
+						// fprData (64), 
+						// stack alignment(8)
+        mflr	r0
+	stw	r0,116(sp)			// save LR backchain
+
+	stw	r4,12(sp)			// save GP registers
+	stw	r5,16(sp)			// (n.b. that we don't save r3
+	stw	r6,20(sp)			// because PrepareAndDispatch() is savvy)
+	stw	r7,24(sp)
+	stw	r8,28(sp)
+	stw	r9,32(sp)
+	stw	r10,36(sp)
+#ifndef __NO_FPRS__
+	stfd	f1,40(sp)			// save FP registers
+	stfd	f2,48(sp)
+	stfd	f3,56(sp)
+	stfd	f4,64(sp)
+	stfd	f5,72(sp)
+	stfd	f6,80(sp)
+	stfd	f7,88(sp)
+	stfd	f8,96(sp)
+#endif
+
+						// r3 has the 'self' pointer already
+	
+	mr      r4,r11				// r4 <= methodIndex selector, passed
+						// via r11 in the nsXPTCStubBase::StubXX() call
+	
+	addi	r5,sp,120			// r5 <= pointer to callers args area,
+						// beyond r3-r10/f1-f8 mapped range
+	
+	addi	r6,sp,8				// r6 <= gprData
+#ifndef __NO_FPRS__
+	addi	r7,sp,40			// r7 <= fprData
+#else
+	li	r7, 0				// r7 should be unused
+#endif
+      
+	bl	PrepareAndDispatch@local	// Go!
+    
+	lwz	r0,116(sp)			// restore LR
+	mtlr	r0
+	la	sp,112(sp)			// clean up the stack
+	blr
+
+/* Magic indicating no need for an executable stack */
+.section .note.GNU-stack, "", @progbits ; .previous
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc_netbsd.s b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc_netbsd.s
new file mode 100644
index 000000000..8d43165ba
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc_netbsd.s
@@ -0,0 +1,70 @@
+# -*- Mode: Asm -*-
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+.set r0,0; .set sp,1; .set RTOC,2; .set r3,3; .set r4,4
+.set r5,5; .set r6,6; .set r7,7; .set r8,8; .set r9,9
+.set r10,10; .set r11,11; .set r12,12; .set r13,13; .set r14,14
+.set r15,15; .set r16,16; .set r17,17; .set r18,18; .set r19,19
+.set r20,20; .set r21,21; .set r22,22; .set r23,23; .set r24,24
+.set r25,25; .set r26,26; .set r27,27; .set r28,28; .set r29,29
+.set r30,30; .set r31,31
+.set f0,0; .set f1,1; .set f2,2; .set f3,3; .set f4,4
+.set f5,5; .set f6,6; .set f7,7; .set f8,8; .set f9,9
+.set f10,10; .set f11,11; .set f12,12; .set f13,13; .set f14,14
+.set f15,15; .set f16,16; .set f17,17; .set f18,18; .set f19,19
+.set f20,20; .set f21,21; .set f22,22; .set f23,23; .set f24,24
+.set f25,25; .set f26,26; .set f27,27; .set f28,28; .set f29,29
+.set f30,30; .set f31,31
+
+        .section ".text"
+        .align 2
+	.globl SharedStub
+	.type  SharedStub,@function
+
+SharedStub:
+        stwu	sp,-112(sp)			# room for 
+						# linkage (8),
+						# gprData (32),
+						# fprData (64), 
+						# stack alignment(8)
+        mflr	r0
+	stw	r0,116(sp)			# save LR backchain
+
+	stw	r4,12(sp)			# save GP registers
+	stw	r5,16(sp)			# (n.b. that we don't save r3
+	stw	r6,20(sp)			# because PrepareAndDispatch() is savvy)
+	stw	r7,24(sp)
+	stw	r8,28(sp)
+	stw	r9,32(sp)
+	stw	r10,36(sp)
+
+	stfd	f1,40(sp)			# save FP registers
+	stfd	f2,48(sp)
+	stfd	f3,56(sp)
+	stfd	f4,64(sp)
+	stfd	f5,72(sp)
+	stfd	f6,80(sp)
+	stfd	f7,88(sp)
+	stfd	f8,96(sp)
+
+						# r3 has the 'self' pointer already
+	
+	mr      r4,r11				# r4 <= methodIndex selector, passed
+						# via r11 in the nsXPTCStubBase::StubXX() call
+	
+	addi	r5,sp,120			# r5 <= pointer to callers args area,
+						# beyond r3-r10/f1-f8 mapped range
+	
+	addi	r6,sp,8				# r6 <= gprData
+	addi	r7,sp,40			# r7 <= fprData
+      
+	bl	PrepareAndDispatch@local	# Go!
+    
+	lwz	r0,116(sp)			# restore LR
+	mtlr	r0
+	la	sp,112(sp)			# clean up the stack
+	blr
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc_openbsd.S b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc_openbsd.S
new file mode 100644
index 000000000..dcca08205
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_ppc_openbsd.S
@@ -0,0 +1,72 @@
+// -*- Mode: Asm -*-
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+.set r0,0; .set sp,1; .set RTOC,2; .set r3,3; .set r4,4
+.set r5,5; .set r6,6; .set r7,7; .set r8,8; .set r9,9
+.set r10,10; .set r11,11; .set r12,12; .set r13,13; .set r14,14
+.set r15,15; .set r16,16; .set r17,17; .set r18,18; .set r19,19
+.set r20,20; .set r21,21; .set r22,22; .set r23,23; .set r24,24
+.set r25,25; .set r26,26; .set r27,27; .set r28,28; .set r29,29
+.set r30,30; .set r31,31
+.set f0,0; .set f1,1; .set f2,2; .set f3,3; .set f4,4
+.set f5,5; .set f6,6; .set f7,7; .set f8,8; .set f9,9
+.set f10,10; .set f11,11; .set f12,12; .set f13,13; .set f14,14
+.set f15,15; .set f16,16; .set f17,17; .set f18,18; .set f19,19
+.set f20,20; .set f21,21; .set f22,22; .set f23,23; .set f24,24
+.set f25,25; .set f26,26; .set f27,27; .set f28,28; .set f29,29
+.set f30,30; .set f31,31
+
+	.section ".text"
+	.align 2
+	.globl SharedStub
+	.type  SharedStub,@function
+
+SharedStub:
+	stwu	sp,-112(sp)			// room for
+						// linkage (8),
+						// gprData (32),
+						// fprData (64),
+						// stack alignment(8)
+	mflr	r0
+	stw	r0,116(sp)			// save LR backchain
+
+	stw	r4,12(sp)			// save GP registers
+	stw	r5,16(sp)			// (n.b. that we don't save r3
+	stw	r6,20(sp)			// because PrepareAndDispatch() is savvy)
+	stw	r7,24(sp)
+	stw	r8,28(sp)
+	stw	r9,32(sp)
+	stw	r10,36(sp)
+
+	stfd	f1,40(sp)			// save FP registers
+	stfd	f2,48(sp)
+	stfd	f3,56(sp)
+	stfd	f4,64(sp)
+	stfd	f5,72(sp)
+	stfd	f6,80(sp)
+	stfd	f7,88(sp)
+	stfd	f8,96(sp)
+
+						// r3 has the 'self' pointer already
+
+	mr	r4,r11				// r4 <= methodIndex selector, passed
+						// via r11 in the nsXPTCStubBase::StubXX() call
+
+	addi	r5,sp,120			// r5 <= pointer to callers args area,
+						// beyond r3-r10/f1-f8 mapped range
+
+	addi	r6,sp,8				// r6 <= gprData
+	addi	r7,sp,40			// r7 <= fprData
+
+	bl	PrepareAndDispatch@local	// Go!
+
+	lwz	r0,116(sp)			// restore LR
+	mtlr	r0
+	la	sp,112(sp)			// clean up the stack
+	blr
+
+// Magic indicating no need for an executable stack
+.section .note.GNU-stack, "", @progbits ; .previous
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_sparc64_openbsd.s b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_sparc64_openbsd.s
new file mode 100644
index 000000000..ab97a890c
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_sparc64_openbsd.s
@@ -0,0 +1,50 @@
+/* -*- Mode: asm; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+        .global SharedStub
+
+/*
+    in the frame for the function that called SharedStub are the
+    rest of the parameters we need
+
+*/
+
+SharedStub:
+! we don't create a new frame yet, but work within the frame of the calling
+! function to give ourselves the other parameters we want
+
+        mov     %o0, %o1               ! shuffle the index up to 2nd place
+        mov     %i0, %o0               ! the original 'this'
+        add     %fp, 0x7ff + 136, %o2  ! previous stack top adjusted to the first argument slot (beyond 'this')
+
+! save off the original incoming parameters that arrived in 
+! registers, the ABI guarantees the space for us to do this
+        stx     %i1, [%fp + 0x7ff + 136]
+        stx     %i2, [%fp + 0x7ff + 144]
+        stx     %i3, [%fp + 0x7ff + 152]
+        stx     %i4, [%fp + 0x7ff + 160]
+        stx     %i5, [%fp + 0x7ff + 168]
+! now we can build our own stack frame
+        save    %sp,-(128 + 64),%sp    ! room for the register window and
+                                       ! struct pointer, rounded up to 0 % 64
+! our function now appears to have been called
+! as SharedStub(nsISupports* that, uint32_t index, uint32_t* args)
+! so we can just copy these through
+
+        mov     %i0, %o0
+        mov     %i1, %o1
+        mov     %i2, %o2
+        call    PrepareAndDispatch
+        nop
+        mov     %o0,%i0             ! propagate return value
+        b .LL1
+        nop
+.LL1:
+        ret
+        restore
+
+       .size    SharedStub, .-SharedStub
+       .type    SharedStub, #function
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_sparc_netbsd.s b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_sparc_netbsd.s
new file mode 100644
index 000000000..9b448d7c7
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_sparc_netbsd.s
@@ -0,0 +1,49 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+        .global SharedStub
+
+/*
+    in the frame for the function that called SharedStub are the
+    rest of the parameters we need
+
+*/
+
+SharedStub:
+! we don't create a new frame yet, but work within the frame of the calling
+! function to give ourselves the other parameters we want
+
+        mov     %o0, %o1            ! shuffle the index up to 2nd place
+        mov     %i0, %o0            ! the original 'this'
+        add     %fp, 72, %o2        ! previous stack top adjusted to the first argument slot (beyond 'this')
+! save off the original incoming parameters that arrived in 
+! registers, the ABI guarantees the space for us to do this
+        st      %i1, [%fp + 72]
+        st      %i2, [%fp + 76]
+        st      %i3, [%fp + 80]
+        st      %i4, [%fp + 84]
+        st      %i5, [%fp + 88]
+! now we can build our own stack frame
+        save    %sp,-(64 + 32),%sp   ! room for the register window and
+                                    ! struct pointer, rounded up to 0 % 32
+! our function now appears to have been called
+! as SharedStub(nsISupports* that, uint32_t index, uint32_t* args)
+! so we can just copy these through
+        
+        mov     %i0, %o0
+        mov     %i1, %o1
+        mov     %i2, %o2
+        call    PrepareAndDispatch
+        nop
+        mov     %o0,%i0             ! propagate return value
+        b .LL1
+        nop
+.LL1:
+        ret
+        restore
+
+       .size    SharedStub, .-SharedStub
+       .type    SharedStub, #function
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_sparc_openbsd.s b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_sparc_openbsd.s
new file mode 100644
index 000000000..871556d4c
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_sparc_openbsd.s
@@ -0,0 +1,49 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+        .global SharedStub
+
+/*
+    in the frame for the function that called SharedStub are the
+    rest of the parameters we need
+
+*/
+
+SharedStub:
+! we don't create a new frame yet, but work within the frame of the calling
+! function to give ourselves the other parameters we want
+
+        mov     %o0, %o1            ! shuffle the index up to 2nd place
+        mov     %i0, %o0            ! the original 'this'
+        add     %fp, 72, %o2        ! previous stack top adjusted to the first argument slot (beyond 'this')
+! save off the original incoming parameters that arrived in 
+! registers, the ABI guarantees the space for us to do this
+        st      %i1, [%fp + 72]
+        st      %i2, [%fp + 76]
+        st      %i3, [%fp + 80]
+        st      %i4, [%fp + 84]
+        st      %i5, [%fp + 88]
+! now we can build our own stack frame
+        save    %sp,-(64 + 32),%sp  ! room for the register window and
+                                    ! struct pointer, rounded up to 0 % 32
+! our function now appears to have been called
+! as SharedStub(nsISupports* that, uint32_t index, uint32_t* args)
+! so we can just copy these through
+        
+        mov     %i0, %o0
+        mov     %i1, %o1
+        mov     %i2, %o2
+        call    PrepareAndDispatch
+        nop
+        mov     %o0,%i0             ! propagate return value
+        b .LL1
+        nop
+.LL1:
+        ret
+        restore
+
+       .size    SharedStub, .-SharedStub
+       .type    SharedStub, #function
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_sparc_solaris.s b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_sparc_solaris.s
new file mode 100644
index 000000000..9b448d7c7
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_sparc_solaris.s
@@ -0,0 +1,49 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+        .global SharedStub
+
+/*
+    in the frame for the function that called SharedStub are the
+    rest of the parameters we need
+
+*/
+
+SharedStub:
+! we don't create a new frame yet, but work within the frame of the calling
+! function to give ourselves the other parameters we want
+
+        mov     %o0, %o1            ! shuffle the index up to 2nd place
+        mov     %i0, %o0            ! the original 'this'
+        add     %fp, 72, %o2        ! previous stack top adjusted to the first argument slot (beyond 'this')
+! save off the original incoming parameters that arrived in 
+! registers, the ABI guarantees the space for us to do this
+        st      %i1, [%fp + 72]
+        st      %i2, [%fp + 76]
+        st      %i3, [%fp + 80]
+        st      %i4, [%fp + 84]
+        st      %i5, [%fp + 88]
+! now we can build our own stack frame
+        save    %sp,-(64 + 32),%sp   ! room for the register window and
+                                    ! struct pointer, rounded up to 0 % 32
+! our function now appears to have been called
+! as SharedStub(nsISupports* that, uint32_t index, uint32_t* args)
+! so we can just copy these through
+        
+        mov     %i0, %o0
+        mov     %i1, %o1
+        mov     %i2, %o2
+        call    PrepareAndDispatch
+        nop
+        mov     %o0,%i0             ! propagate return value
+        b .LL1
+        nop
+.LL1:
+        ret
+        restore
+
+       .size    SharedStub, .-SharedStub
+       .type    SharedStub, #function
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_sparcv9_solaris.s b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_sparcv9_solaris.s
new file mode 100644
index 000000000..ab97a890c
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_sparcv9_solaris.s
@@ -0,0 +1,50 @@
+/* -*- Mode: asm; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+        .global SharedStub
+
+/*
+    in the frame for the function that called SharedStub are the
+    rest of the parameters we need
+
+*/
+
+SharedStub:
+! we don't create a new frame yet, but work within the frame of the calling
+! function to give ourselves the other parameters we want
+
+        mov     %o0, %o1               ! shuffle the index up to 2nd place
+        mov     %i0, %o0               ! the original 'this'
+        add     %fp, 0x7ff + 136, %o2  ! previous stack top adjusted to the first argument slot (beyond 'this')
+
+! save off the original incoming parameters that arrived in 
+! registers, the ABI guarantees the space for us to do this
+        stx     %i1, [%fp + 0x7ff + 136]
+        stx     %i2, [%fp + 0x7ff + 144]
+        stx     %i3, [%fp + 0x7ff + 152]
+        stx     %i4, [%fp + 0x7ff + 160]
+        stx     %i5, [%fp + 0x7ff + 168]
+! now we can build our own stack frame
+        save    %sp,-(128 + 64),%sp    ! room for the register window and
+                                       ! struct pointer, rounded up to 0 % 64
+! our function now appears to have been called
+! as SharedStub(nsISupports* that, uint32_t index, uint32_t* args)
+! so we can just copy these through
+
+        mov     %i0, %o0
+        mov     %i1, %o1
+        mov     %i2, %o2
+        call    PrepareAndDispatch
+        nop
+        mov     %o0,%i0             ! propagate return value
+        b .LL1
+        nop
+.LL1:
+        ret
+        restore
+
+       .size    SharedStub, .-SharedStub
+       .type    SharedStub, #function
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_x86_64_solaris_SUNW.s b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_x86_64_solaris_SUNW.s
new file mode 100644
index 000000000..aa6d84434
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_x86_64_solaris_SUNW.s
@@ -0,0 +1,63 @@
+#define STUB_ENTRY1(nn) \
+    .globl	__1cOnsXPTCStubBaseFStub/**/nn/**/6M_I_; \
+    .hidden	__1cOnsXPTCStubBaseFStub/**/nn/**/6M_I_; \
+    .type	__1cOnsXPTCStubBaseFStub/**/nn/**/6M_I_, @function; \
+__1cOnsXPTCStubBaseFStub/**/nn/**/6M_I_: \
+    movl	$/**/nn/**/, %eax; \
+    jmp	SharedStub; \
+    .size	__1cOnsXPTCStubBaseFStub/**/nn/**/6M_I_, . - __1cOnsXPTCStubBaseFStub/**/nn/**/6M_I_ \
+
+#define STUB_ENTRY2(nn) \
+    .globl	__1cOnsXPTCStubBaseGStub/**/nn/**/6M_I_; \
+    .hidden	__1cOnsXPTCStubBaseGStub/**/nn/**/6M_I_; \
+    .type	__1cOnsXPTCStubBaseGStub/**/nn/**/6M_I_, @function; \
+__1cOnsXPTCStubBaseGStub/**/nn/**/6M_I_: \
+    movl	$/**/nn/**/, %eax; \
+    jmp	SharedStub; \
+    .size	__1cOnsXPTCStubBaseGStub/**/nn/**/6M_I_, . - __1cOnsXPTCStubBaseGStub/**/nn/**/6M_I_ \
+
+#define STUB_ENTRY3(nn) \
+    .globl	__1cOnsXPTCStubBaseHStub/**/nn/**/6M_I_; \
+    .hidden	__1cOnsXPTCStubBaseHStub/**/nn/**/6M_I_; \
+    .type	__1cOnsXPTCStubBaseHStub/**/nn/**/6M_I_, @function; \
+__1cOnsXPTCStubBaseHStub/**/nn/**/6M_I_: \
+    movl	$/**/nn/**/, %eax; \
+    jmp	SharedStub; \
+    .size	__1cOnsXPTCStubBaseHStub/**/nn/**/6M_I_, . - __1cOnsXPTCStubBaseHStub/**/nn/**/6M_I_ \
+
+// static nsresult SharedStub(uint32_t methodIndex)
+    .type      SharedStub, @function;
+    SharedStub:
+    // make room for gpregs (48), fpregs (64)
+    pushq      %rbp;
+    movq       %rsp,%rbp;
+    subq       $112,%rsp;
+    // save GP registers
+    movq       %rdi,-112(%rbp);
+    movq       %rsi,-104(%rbp);
+    movq       %rdx, -96(%rbp);
+    movq       %rcx, -88(%rbp);
+    movq       %r8 , -80(%rbp);
+    movq       %r9 , -72(%rbp);
+    leaq       -112(%rbp),%rcx;
+    // save FP registers
+    movsd      %xmm0,-64(%rbp);
+    movsd      %xmm1,-56(%rbp);
+    movsd      %xmm2,-48(%rbp);
+    movsd      %xmm3,-40(%rbp);
+    movsd      %xmm4,-32(%rbp);
+    movsd      %xmm5,-24(%rbp);
+    movsd      %xmm6,-16(%rbp);
+    movsd      %xmm7, -8(%rbp);
+    leaq       -64(%rbp),%r8;
+    // rdi has the 'self' pointer already
+    movl       %eax,%esi;
+    leaq       16(%rbp),%rdx;
+    call       PrepareAndDispatch@plt;
+    leave;
+    ret;
+    .size      SharedStub, . - SharedStub
+
+#define SENTINEL_ENTRY(nn)
+
+#include "xptcstubsdef_asm.solx86"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_x86_solaris_SUNW.s b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_x86_solaris_SUNW.s
new file mode 100644
index 000000000..76bdcf925
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_asm_x86_solaris_SUNW.s
@@ -0,0 +1,78 @@
+#define STUB_ENTRY1(nn)	\
+ 	.globl __1cOnsXPTCStubBaseFStub/**/nn/**/6M_I_; \
+	.type __1cOnsXPTCStubBaseFStub/**/nn/**/6M_I_, @function; \
+__1cOnsXPTCStubBaseFStub/**/nn/**/6M_I_: \
+	push       %ebp; \
+	movl       %esp,%ebp; \
+	andl       $-16,%esp; \
+	push       %ebx;	\
+	call       .CG4./**/nn/**/; \
+.CG4./**/nn/**/: \
+	pop        %ebx;	 \
+	addl       $_GLOBAL_OFFSET_TABLE_+0x1,%ebx; \
+	leal	0xc(%ebp), %ecx; \
+	pushl	%ecx; \
+	pushl	$/**/nn/**/; \
+	movl	0x8(%ebp), %ecx; \
+	pushl	%ecx; \
+	call	__1cSPrepareAndDispatch6FpnOnsXPTCStubBase_IpI_I_; \
+	addl	$0xc , %esp; \
+	pop        %ebx; \
+	movl       %ebp,%esp; \
+	pop        %ebp; \
+	ret        ; \
+	.size __1cOnsXPTCStubBaseFStub/**/nn/**/6M_I_, . - __1cOnsXPTCStubBaseFStub/**/nn/**/6M_I_ \
+
+#define STUB_ENTRY2(nn)	\
+ 	.globl __1cOnsXPTCStubBaseGStub/**/nn/**/6M_I_; \
+	.type __1cOnsXPTCStubBaseGStub/**/nn/**/6M_I_, @function; \
+__1cOnsXPTCStubBaseGStub/**/nn/**/6M_I_: \
+	push       %ebp; \
+	movl       %esp,%ebp; \
+	andl       $-16,%esp; \
+	push       %ebx;	\
+	call       .CG4./**/nn/**/; \
+.CG4./**/nn/**/: \
+	pop        %ebx;	 \
+	addl       $_GLOBAL_OFFSET_TABLE_+0x1,%ebx; \
+	leal	0xc(%ebp), %ecx; \
+	pushl	%ecx; \
+	pushl	$/**/nn/**/; \
+	movl	0x8(%ebp), %ecx; \
+	pushl	%ecx; \
+	call	__1cSPrepareAndDispatch6FpnOnsXPTCStubBase_IpI_I_; \
+	addl	$0xc , %esp; \
+	pop        %ebx; \
+	movl       %ebp,%esp; \
+	pop        %ebp; \
+	ret        ; \
+	.size __1cOnsXPTCStubBaseGStub/**/nn/**/6M_I_, . - __1cOnsXPTCStubBaseGStub/**/nn/**/6M_I_ \
+
+#define STUB_ENTRY3(nn)	\
+ 	.globl __1cOnsXPTCStubBaseHStub/**/nn/**/6M_I_; \
+	.type __1cOnsXPTCStubBaseHStub/**/nn/**/6M_I_, @function; \
+__1cOnsXPTCStubBaseHStub/**/nn/**/6M_I_: \
+	push       %ebp; \
+	movl       %esp,%ebp; \
+	andl       $-16,%esp; \
+	push       %ebx;	\
+	call       .CG4./**/nn/**/; \
+.CG4./**/nn/**/: \
+	pop        %ebx;	 \
+	addl       $_GLOBAL_OFFSET_TABLE_+0x1,%ebx; \
+	leal	0xc(%ebp), %ecx; \
+	pushl	%ecx; \
+	pushl	$/**/nn/**/; \
+	movl	0x8(%ebp), %ecx; \
+	pushl	%ecx; \
+	call	__1cSPrepareAndDispatch6FpnOnsXPTCStubBase_IpI_I_; \
+	addl	$0xc , %esp; \
+	pop        %ebx; \
+	movl       %ebp,%esp; \
+	pop        %ebp; \
+	ret        ; \
+	.size __1cOnsXPTCStubBaseHStub/**/nn/**/6M_I_, . - __1cOnsXPTCStubBaseHStub/**/nn/**/6M_I_ \
+
+#define SENTINEL_ENTRY(nn)
+
+#include "xptcstubsdef_asm.solx86"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_darwin.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_darwin.cpp
new file mode 100644
index 000000000..49edfca44
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_darwin.cpp
@@ -0,0 +1,16 @@
+/* -*- Mode: C -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#if defined(__i386__)
+#include "xptcstubs_gcc_x86_unix.cpp"
+#elif defined(__x86_64__)
+#include "xptcstubs_x86_64_darwin.cpp"
+#elif defined(__ppc__)
+#include "xptcstubs_ppc_rhapsody.cpp"
+#elif defined(__arm__)
+#include "xptcstubs_arm.cpp"
+#else
+#error unknown cpu architecture
+#endif
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_gcc_x86_unix.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_gcc_x86_unix.cpp
new file mode 100644
index 000000000..6811a26ad
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_gcc_x86_unix.cpp
@@ -0,0 +1,139 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+#include "xptc_gcc_x86_unix.h"
+
+extern "C" {
+static nsresult ATTRIBUTE_USED
+__attribute__ ((regparm (3)))
+PrepareAndDispatch(uint32_t methodIndex, nsXPTCStubBase* self, uint32_t* args)
+{
+#define PARAM_BUFFER_COUNT     16
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+    NS_ASSERTION(dispatchParams,"no place for params");
+
+    uint32_t* ap = args;
+    for(i = 0; i < paramCount; i++, ap++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            dp->val.p = (void*) *ap;
+            continue;
+        }
+        // else
+	    dp->val.p = (void*) *ap;
+        switch(type)
+        {
+        case nsXPTType::T_I64    : dp->val.i64 = *((int64_t*) ap); ap++; break;
+        case nsXPTType::T_U64    : dp->val.u64 = *((uint64_t*)ap); ap++; break;
+        case nsXPTType::T_DOUBLE : dp->val.d   = *((double*)  ap); ap++; break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+} // extern "C"
+
+#if !defined(XP_MACOSX)
+
+#define STUB_HEADER(a, b) ".hidden " SYMBOL_UNDERSCORE "_ZN14nsXPTCStubBase" #a "Stub" #b "Ev\n\t" \
+                          ".type   " SYMBOL_UNDERSCORE "_ZN14nsXPTCStubBase" #a "Stub" #b "Ev,@function\n"
+
+#define STUB_SIZE(a, b)  ".size        " SYMBOL_UNDERSCORE "_ZN14nsXPTCStubBase" #a "Stub" #b "Ev,.-" SYMBOL_UNDERSCORE "_ZN14nsXPTCStubBase" #a "Stub" #b "Ev\n\t"
+
+#else
+
+#define STUB_HEADER(a, b)
+#define STUB_SIZE(a, b)
+
+#endif
+
+// gcc3 mangling tends to insert the length of the method name
+#define STUB_ENTRY(n) \
+asm(".text\n\t" \
+    ".align	2\n\t" \
+    ".if	" #n " < 10\n\t" \
+    ".globl	" SYMBOL_UNDERSCORE "_ZN14nsXPTCStubBase5Stub" #n "Ev\n\t" \
+    STUB_HEADER(5, n)                                                   \
+    SYMBOL_UNDERSCORE "_ZN14nsXPTCStubBase5Stub" #n "Ev:\n\t" \
+    ".elseif	" #n " < 100\n\t" \
+    ".globl	" SYMBOL_UNDERSCORE "_ZN14nsXPTCStubBase6Stub" #n "Ev\n\t" \
+    STUB_HEADER(6, n)                                                   \
+    SYMBOL_UNDERSCORE "_ZN14nsXPTCStubBase6Stub" #n "Ev:\n\t" \
+    ".elseif    " #n " < 1000\n\t" \
+    ".globl     " SYMBOL_UNDERSCORE "_ZN14nsXPTCStubBase7Stub" #n "Ev\n\t" \
+    STUB_HEADER(7, n)                                                   \
+    SYMBOL_UNDERSCORE "_ZN14nsXPTCStubBase7Stub" #n "Ev:\n\t" \
+    ".else\n\t" \
+    ".err	\"stub number " #n " >= 1000 not yet supported\"\n\t" \
+    ".endif\n\t" \
+    "movl	$" #n ", %eax\n\t" \
+    "jmp	" SYMBOL_UNDERSCORE "SharedStub\n\t" \
+    ".if	" #n " < 10\n\t" \
+    STUB_SIZE(5, n) \
+    ".elseif	" #n " < 100\n\t" \
+    STUB_SIZE(6, n) \
+    ".else\n\t" \
+    STUB_SIZE(7, n) \
+    ".endif");
+
+// static nsresult SharedStub(uint32_t methodIndex) __attribute__((regparm(1)))
+asm(".text\n\t"
+    ".align	2\n\t"
+#if !defined(XP_MACOSX)
+    ".type	" SYMBOL_UNDERSCORE "SharedStub,@function\n\t"
+#endif
+    SYMBOL_UNDERSCORE "SharedStub:\n\t"
+    "leal	0x08(%esp), %ecx\n\t"
+    "movl	0x04(%esp), %edx\n\t"
+    "jmp	" SYMBOL_UNDERSCORE "PrepareAndDispatch\n\t"
+#if !defined(XP_MACOSX)
+    ".size	" SYMBOL_UNDERSCORE "SharedStub,.-" SYMBOL_UNDERSCORE "SharedStub"
+#endif
+);
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
+
+void
+xptc_dummy()
+{
+}
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_ipf32.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_ipf32.cpp
new file mode 100644
index 000000000..e2d37e4f5
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_ipf32.cpp
@@ -0,0 +1,151 @@
+
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+#include <stddef.h>
+#include <stdlib.h>
+
+// "This code is for IA64 only"
+
+/* Implement shared vtbl methods. */
+
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex,
+  uint64_t* intargs, uint64_t* floatargs, uint64_t* restargs)
+{
+
+#define PARAM_BUFFER_COUNT     16
+
+  nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+  nsXPTCMiniVariant* dispatchParams = nullptr;
+  const nsXPTMethodInfo* info;
+  nsresult result = NS_ERROR_FAILURE;
+  uint64_t* iargs = intargs;
+  uint64_t* fargs = floatargs;
+  uint8_t paramCount;
+  uint8_t i;
+
+  NS_ASSERTION(self,"no self");
+
+  self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+  NS_ASSERTION(info,"no interface info");
+
+  paramCount = info->GetParamCount();
+
+  // setup variant array pointer
+  if(paramCount > PARAM_BUFFER_COUNT)
+    dispatchParams = new nsXPTCMiniVariant[paramCount];
+  else
+    dispatchParams = paramBuffer;
+  NS_ASSERTION(dispatchParams,"no place for params");
+  if (! dispatchParams)
+      return NS_ERROR_OUT_OF_MEMORY;
+
+  for(i = 0; i < paramCount; ++i)
+  {
+    int isfloat = 0;
+    const nsXPTParamInfo& param = info->GetParam(i);
+    const nsXPTType& type = param.GetType();
+    nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+    if(param.IsOut() || !type.IsArithmetic())
+    {
+#ifdef __LP64__
+        /* 64 bit pointer mode */
+        dp->val.p = (void*) *iargs;
+#else
+        /* 32 bit pointer mode */
+        uint32_t* adr = (uint32_t*) iargs;
+        dp->val.p = (void*) (*(adr+1));
+#endif
+    }
+    else
+    switch(type)
+    {
+    case nsXPTType::T_I8     : dp->val.i8  = *(iargs); break;
+    case nsXPTType::T_I16    : dp->val.i16 = *(iargs); break;
+    case nsXPTType::T_I32    : dp->val.i32 = *(iargs); break;
+    case nsXPTType::T_I64    : dp->val.i64 = *(iargs); break;
+    case nsXPTType::T_U8     : dp->val.u8  = *(iargs); break;
+    case nsXPTType::T_U16    : dp->val.u16 = *(iargs); break;
+    case nsXPTType::T_U32    : dp->val.u32 = *(iargs); break;
+    case nsXPTType::T_U64    : dp->val.u64 = *(iargs); break;
+    case nsXPTType::T_FLOAT  :
+      isfloat = 1;
+      if (i < 7)
+        dp->val.f = (float) *((double*) fargs); /* register */
+      else
+        dp->val.u32 = *(fargs); /* memory */
+      break;
+    case nsXPTType::T_DOUBLE :
+      isfloat = 1;
+      dp->val.u64 = *(fargs);
+      break;
+    case nsXPTType::T_BOOL   : dp->val.b   = *(iargs); break;
+    case nsXPTType::T_CHAR   : dp->val.c   = *(iargs); break;
+    case nsXPTType::T_WCHAR  : dp->val.wc  = *(iargs); break;
+    default:
+      NS_ERROR("bad type");
+      break;
+    }
+    if (i < 7)
+    {
+      /* we are parsing register arguments */
+      if (i == 6)
+      {
+        // run out of register arguments, move on to memory arguments
+        iargs = restargs;
+        fargs = restargs;
+      }
+      else
+      {
+        ++iargs; // advance one integer register slot
+        if (isfloat) ++fargs; // advance float register slot if isfloat
+      }
+    }
+    else
+    {
+      /* we are parsing memory arguments */
+      ++iargs;
+      ++fargs;
+    }
+  }
+
+  result = self->mOuter->CallMethod((uint16_t) methodIndex, info, dispatchParams);
+
+  if(dispatchParams != paramBuffer)
+    delete [] dispatchParams;
+
+  return result;
+}
+
+extern "C" nsresult SharedStub(uint64_t,uint64_t,uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t *);
+
+/* Variable a0-a7 were put there so we can have access to the 8 input
+   registers on Stubxyz entry */
+
+#define STUB_ENTRY(n) \
+nsresult nsXPTCStubBase::Stub##n(uint64_t a1, \
+uint64_t a2,uint64_t a3,uint64_t a4,uint64_t a5,uint64_t a6,uint64_t a7, \
+uint64_t a8) \
+{ uint64_t a0 = (uint64_t) this; \
+ return SharedStub(a0,a1,a2,a3,a4,a5,a6,a7,(uint64_t) n, &a8); \
+}
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_ipf64.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_ipf64.cpp
new file mode 100644
index 000000000..fea9e8e3d
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_ipf64.cpp
@@ -0,0 +1,154 @@
+
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+// "This code is for IA64 only"
+
+/* Implement shared vtbl methods. */
+
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex,
+  uint64_t* intargs, uint64_t* floatargs, uint64_t* restargs)
+{
+
+#define PARAM_BUFFER_COUNT     16
+
+  nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+  nsXPTCMiniVariant* dispatchParams = nullptr;
+  const nsXPTMethodInfo* info;
+  nsresult result = NS_ERROR_FAILURE;
+  uint64_t* iargs = intargs;
+  uint64_t* fargs = floatargs;
+  uint8_t paramCount;
+  uint8_t i;
+
+  NS_ASSERTION(self,"no self");
+
+  self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+  NS_ASSERTION(info,"no method info");
+  if (! info)
+      return NS_ERROR_UNEXPECTED;
+
+  paramCount = info->GetParamCount();
+
+  // setup variant array pointer
+  if(paramCount > PARAM_BUFFER_COUNT)
+    dispatchParams = new nsXPTCMiniVariant[paramCount];
+  else
+    dispatchParams = paramBuffer;
+  NS_ASSERTION(dispatchParams,"no place for params");
+  if (! dispatchParams)
+      return NS_ERROR_OUT_OF_MEMORY;
+
+  for(i = 0; i < paramCount; ++i)
+  {
+    int isfloat = 0;
+    const nsXPTParamInfo& param = info->GetParam(i);
+    const nsXPTType& type = param.GetType();
+    nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+    if(param.IsOut() || !type.IsArithmetic())
+    {
+#ifdef __LP64__
+        /* 64 bit pointer mode */
+        dp->val.p = (void*) *iargs;
+#else
+        /* 32 bit pointer mode */
+        uint32_t* adr = (uint32_t*) iargs;
+        dp->val.p = (void*) (*(adr+1));
+#endif
+    }
+    else
+    switch(type)
+    {
+    case nsXPTType::T_I8     : dp->val.i8  = *(iargs); break;
+    case nsXPTType::T_I16    : dp->val.i16 = *(iargs); break;
+    case nsXPTType::T_I32    : dp->val.i32 = *(iargs); break;
+    case nsXPTType::T_I64    : dp->val.i64 = *(iargs); break;
+    case nsXPTType::T_U8     : dp->val.u8  = *(iargs); break;
+    case nsXPTType::T_U16    : dp->val.u16 = *(iargs); break;
+    case nsXPTType::T_U32    : dp->val.u32 = *(iargs); break;
+    case nsXPTType::T_U64    : dp->val.u64 = *(iargs); break;
+    case nsXPTType::T_FLOAT  :
+      isfloat = 1;
+      if (i < 7)
+        dp->val.f = (float) *((double*) fargs); /* register */
+      else
+        dp->val.u32 = *(fargs); /* memory */
+      break;
+    case nsXPTType::T_DOUBLE :
+      isfloat = 1;
+      dp->val.u64 = *(fargs);
+      break;
+    case nsXPTType::T_BOOL   : dp->val.b   = *(iargs); break;
+    case nsXPTType::T_CHAR   : dp->val.c   = *(iargs); break;
+    case nsXPTType::T_WCHAR  : dp->val.wc  = *(iargs); break;
+    default:
+      NS_ERROR("bad type");
+      break;
+    }
+    if (i < 7)
+    {
+      /* we are parsing register arguments */
+      if (i == 6)
+      {
+        // run out of register arguments, move on to memory arguments
+        iargs = restargs;
+        fargs = restargs;
+      }
+      else
+      {
+        ++iargs; // advance one integer register slot
+        if (isfloat) ++fargs; // advance float register slot if isfloat
+      }
+    }
+    else
+    {
+      /* we are parsing memory arguments */
+      ++iargs;
+      ++fargs;
+    }
+  }
+
+  result = self->mOuter->CallMethod((uint16_t) methodIndex, info, dispatchParams);
+
+  if(dispatchParams != paramBuffer)
+    delete [] dispatchParams;
+
+  return result;
+}
+
+extern "C" nsresult SharedStub(uint64_t,uint64_t,uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t *);
+
+/* Variable a0-a7 were put there so we can have access to the 8 input
+   registers on Stubxyz entry */
+
+#define STUB_ENTRY(n) \
+nsresult nsXPTCStubBase::Stub##n(uint64_t a1, \
+uint64_t a2,uint64_t a3,uint64_t a4,uint64_t a5,uint64_t a6,uint64_t a7, \
+uint64_t a8) \
+{ uint64_t a0 = (uint64_t) this; \
+ return SharedStub(a0,a1,a2,a3,a4,a5,a6,a7,(uint64_t) n, &a8); \
+}
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_linux_alpha.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_linux_alpha.cpp
new file mode 100644
index 000000000..d9c41aee7
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_linux_alpha.cpp
@@ -0,0 +1,187 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+/* Prototype specifies unmangled function name and disables unused warning */
+static nsresult
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint64_t* args)
+__asm__("PrepareAndDispatch") ATTRIBUTE_USED;
+
+static nsresult
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint64_t* args)
+{
+    const uint8_t PARAM_BUFFER_COUNT = 16;
+    const uint8_t NUM_ARG_REGS = 6-1;        // -1 for "this" pointer
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+    NS_ASSERTION(dispatchParams,"no place for params");
+
+    // args[0] to args[NUM_ARG_REGS] hold floating point register values
+    uint64_t* ap = args + NUM_ARG_REGS;
+    for(i = 0; i < paramCount; i++, ap++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            dp->val.p = (void*) *ap;
+            continue;
+        }
+        // else
+        switch(type)
+        {
+        case nsXPTType::T_I8     : dp->val.i8  = (int8_t)    *ap;    break;
+        case nsXPTType::T_I16    : dp->val.i16 = (int16_t)   *ap;    break;
+        case nsXPTType::T_I32    : dp->val.i32 = (int32_t)   *ap;    break;
+        case nsXPTType::T_I64    : dp->val.i64 = (int64_t)   *ap;    break;
+        case nsXPTType::T_U8     : dp->val.u8  = (uint8_t)   *ap;    break;
+        case nsXPTType::T_U16    : dp->val.u16 = (uint16_t)  *ap;    break;
+        case nsXPTType::T_U32    : dp->val.u32 = (uint32_t)  *ap;    break;
+        case nsXPTType::T_U64    : dp->val.u64 = (uint64_t)  *ap;    break;
+        case nsXPTType::T_FLOAT  :
+            if(i < NUM_ARG_REGS)
+            {
+                // floats passed via registers are stored as doubles
+                // in the first NUM_ARG_REGS entries in args
+                dp->val.u64 = (uint64_t) args[i];
+                dp->val.f = (float) dp->val.d;    // convert double to float
+            }
+            else
+                dp->val.u32 = (uint32_t) *ap;
+            break;
+        case nsXPTType::T_DOUBLE :
+            // doubles passed via registers are also stored
+            // in the first NUM_ARG_REGS entries in args
+            dp->val.u64 = (i < NUM_ARG_REGS) ? args[i] : *ap;
+            break;
+        case nsXPTType::T_BOOL   : dp->val.b   = (bool)    *ap;    break;
+        case nsXPTType::T_CHAR   : dp->val.c   = (char)      *ap;    break;
+        case nsXPTType::T_WCHAR  : dp->val.wc  = (char16_t) *ap;    break;
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+/*
+ * SharedStub()
+ *  Collects arguments and calls PrepareAndDispatch.  The "methodIndex" is
+ *  passed to this function via $1 to preserve the argument registers.
+ */
+__asm__(
+    "#### SharedStub ####\n"
+".text\n\t"
+    ".align 5\n\t"
+    ".ent SharedStub\n"
+"SharedStub:\n\t"
+    ".frame $30,96,$26,0\n\t"
+    ".mask 0x4000000,-96\n\t"
+    "ldgp $29,0($27)\n"
+"$SharedStub..ng:\n\t"
+    "subq $30,96,$30\n\t"
+    "stq $26,0($30)\n\t"
+    ".prologue 1\n\t"
+
+    /*
+     * Store arguments passed via registers to the stack.
+     * Floating point registers are stored as doubles and converted
+     * to floats in PrepareAndDispatch if necessary.
+     */
+    "stt $f17,16($30)\n\t"   /* floating point registers */
+    "stt $f18,24($30)\n\t"
+    "stt $f19,32($30)\n\t"
+    "stt $f20,40($30)\n\t"
+    "stt $f21,48($30)\n\t"
+    "stq $17,56($30)\n\t"    /* integer registers */
+    "stq $18,64($30)\n\t"
+    "stq $19,72($30)\n\t"
+    "stq $20,80($30)\n\t"
+    "stq $21,88($30)\n\t"
+
+    /*
+     * Call PrepareAndDispatch function.
+     */
+    "bis $1,$1,$17\n\t"      /* pass "methodIndex" */
+    "addq $30,16,$18\n\t"    /* pass "args" */
+    "bsr $26,$PrepareAndDispatch..ng\n\t"
+
+    "ldq $26,0($30)\n\t"
+    "addq $30,96,$30\n\t"
+    "ret $31,($26),1\n\t"
+    ".end SharedStub"
+    );
+
+/*
+ * nsresult nsXPTCStubBase::Stub##n()
+ *  Sets register $1 to "methodIndex" and jumps to SharedStub.
+ */
+#define STUB_MANGLED_ENTRY(n, symbol) \
+    "#### Stub"#n" ####"      "\n\t" \
+    ".text"                   "\n\t" \
+    ".align 5"                "\n\t" \
+    ".globl " symbol          "\n\t" \
+    ".ent " symbol            "\n"   \
+symbol ":"                    "\n\t" \
+    ".frame $30,0,$26,0"      "\n\t" \
+    "ldgp $29,0($27)"         "\n"   \
+"$" symbol "..ng:"            "\n\t" \
+    ".prologue 1"             "\n\t" \
+    "lda $1,"#n               "\n\t" \
+    "br $31,$SharedStub..ng"  "\n\t" \
+    ".end " symbol
+
+#define STUB_ENTRY(n) \
+__asm__( \
+    ".if "#n" < 10"                                              "\n\t" \
+        STUB_MANGLED_ENTRY(n, "_ZN14nsXPTCStubBase5Stub"#n"Ev")  "\n\t" \
+    ".elseif "#n" < 100"                                         "\n\t" \
+        STUB_MANGLED_ENTRY(n, "_ZN14nsXPTCStubBase6Stub"#n"Ev")  "\n\t" \
+    ".elseif "#n" < 1000"                                        "\n\t" \
+        STUB_MANGLED_ENTRY(n, "_ZN14nsXPTCStubBase7Stub"#n"Ev")  "\n\t" \
+    ".else"                                                      "\n\t" \
+    ".err \"Stub"#n" >= 1000 not yet supported.\""               "\n\t" \
+    ".endif" \
+    );
+
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_linux_m68k.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_linux_m68k.cpp
new file mode 100644
index 000000000..3720a5c37
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_linux_m68k.cpp
@@ -0,0 +1,98 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+extern "C" {
+    nsresult ATTRIBUTE_USED
+    PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint32_t* args)
+    {
+#define PARAM_BUFFER_COUNT     16
+
+        nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+        nsXPTCMiniVariant* dispatchParams = nullptr;
+        const nsXPTMethodInfo* info;
+        uint8_t paramCount;
+        uint8_t i;
+        nsresult result = NS_ERROR_FAILURE;
+
+        NS_ASSERTION(self,"no self");
+
+        self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+        NS_ASSERTION(info,"no method info");
+
+        paramCount = info->GetParamCount();
+
+        // setup variant array pointer
+        if(paramCount > PARAM_BUFFER_COUNT)
+            dispatchParams = new nsXPTCMiniVariant[paramCount];
+        else
+            dispatchParams = paramBuffer;
+        NS_ASSERTION(dispatchParams,"no place for params");
+
+        uint32_t* ap = args;
+        for(i = 0; i < paramCount; i++, ap++)
+        {
+            const nsXPTParamInfo& param = info->GetParam(i);
+            const nsXPTType& type = param.GetType();
+            nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+            if(param.IsOut() || !type.IsArithmetic())
+            {
+                dp->val.p = (void*) *ap;
+                continue;
+            }
+
+            switch(type)
+            {
+            // the 8 and 16 bit types will have been promoted to 32 bits before
+            // being pushed onto the stack. Since the 68k is big endian, we
+            // need to skip over the leading high order bytes.
+            case nsXPTType::T_I8     : dp->val.i8  = *(((int8_t*) ap) + 3);  break;
+            case nsXPTType::T_I16    : dp->val.i16 = *(((int16_t*) ap) + 1); break;
+            case nsXPTType::T_I32    : dp->val.i32 = *((int32_t*) ap);       break;
+            case nsXPTType::T_I64    : dp->val.i64 = *((int64_t*) ap); ap++; break;
+            case nsXPTType::T_U8     : dp->val.u8  = *(((uint8_t*) ap) + 3); break;
+            case nsXPTType::T_U16    : dp->val.u16 = *(((uint16_t*)ap) + 1); break;
+            case nsXPTType::T_U32    : dp->val.u32 = *((uint32_t*)ap);       break;
+            case nsXPTType::T_U64    : dp->val.u64 = *((uint64_t*)ap); ap++; break;
+            case nsXPTType::T_FLOAT  : dp->val.f   = *((float*)   ap);       break;
+            case nsXPTType::T_DOUBLE : dp->val.d   = *((double*)  ap); ap++; break;
+            case nsXPTType::T_BOOL   : dp->val.b   = *((uint32_t* ap);       break;
+            case nsXPTType::T_CHAR   : dp->val.c   = *(((char*)   ap) + 3);  break;
+            case nsXPTType::T_WCHAR  : dp->val.wc  = *((wchar_t*) ap);       break;
+            default:
+                NS_ERROR("bad type");
+                break;
+            }
+        }
+
+        result = self->mOuter->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+        if(dispatchParams != paramBuffer)
+            delete [] dispatchParams;
+
+        return result;
+    }
+}
+
+#define STUB_ENTRY(n) \
+nsresult nsXPTCStubBase::Stub##n() \
+{ \
+  void *frame = __builtin_frame_address(0); \
+  return PrepareAndDispatch(this, n, (uint32_t*)frame + 3); \
+}
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_linux_s390.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_linux_s390.cpp
new file mode 100644
index 000000000..cf4ab1268
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_linux_s390.cpp
@@ -0,0 +1,183 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+static nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, 
+                   uint32_t* a_gpr, uint64_t *a_fpr, uint32_t *a_ov)
+{
+#define PARAM_BUFFER_COUNT     16
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no info");
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+    NS_ASSERTION(dispatchParams,"no place for params");
+
+    uint32_t gpr = 1, fpr = 0;
+
+    for(i = 0; i < paramCount; i++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            if (gpr < 5)
+                dp->val.p = (void*) *a_gpr++, gpr++;
+            else
+                dp->val.p = (void*) *a_ov++;
+            continue;
+        }
+        // else
+        switch(type)
+        {
+        case nsXPTType::T_I8     : 
+            if (gpr < 5)
+                dp->val.i8  = *((int32_t*) a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.i8  = *((int32_t*) a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_I16    : 
+            if (gpr < 5)
+                dp->val.i16 = *((int32_t*) a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.i16 = *((int32_t*) a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_I32    : 
+            if (gpr < 5)
+                dp->val.i32 = *((int32_t*) a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.i32 = *((int32_t*) a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_I64    : 
+            if (gpr < 4)
+                dp->val.i64 = *((int64_t*) a_gpr), a_gpr+=2, gpr+=2;
+            else
+                dp->val.i64 = *((int64_t*) a_ov ), a_ov+=2, gpr=5;
+            break;
+        case nsXPTType::T_U8     : 
+            if (gpr < 5)
+                dp->val.u8  = *((uint32_t*)a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.u8  = *((uint32_t*)a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_U16    : 
+            if (gpr < 5)
+                dp->val.u16 = *((uint32_t*)a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.u16 = *((uint32_t*)a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_U32    : 
+            if (gpr < 5)
+                dp->val.u32 = *((uint32_t*)a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.u32 = *((uint32_t*)a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_U64    : 
+            if (gpr < 4)
+                dp->val.u64 = *((uint64_t*)a_gpr), a_gpr+=2, gpr+=2;
+            else
+                dp->val.u64 = *((uint64_t*)a_ov ), a_ov+=2, gpr=5;
+            break;
+        case nsXPTType::T_FLOAT  : 
+            if (fpr < 2)
+                dp->val.f   = *((float*)   a_fpr), a_fpr++, fpr++;
+            else
+                dp->val.f   = *((float*)   a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_DOUBLE : 
+            if (fpr < 2)
+                dp->val.d   = *((double*)  a_fpr), a_fpr++, fpr++;
+            else
+                dp->val.d   = *((double*)  a_ov ), a_ov+=2;
+            break;
+        case nsXPTType::T_BOOL   : 
+            if (gpr < 5)
+                dp->val.b   = *((uint32_t*)a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.b   = *((uint32_t*)a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_CHAR   : 
+            if (gpr < 5)
+                dp->val.c   = *((uint32_t*)a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.c   = *((uint32_t*)a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_WCHAR  : 
+            if (gpr < 5)
+                dp->val.wc  = *((uint32_t*)a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.wc  = *((uint32_t*)a_ov ), a_ov++;
+            break;
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+#define STUB_ENTRY(n) \
+nsresult nsXPTCStubBase::Stub##n() \
+{                             \
+    uint32_t a_gpr[4];        \
+    uint64_t a_fpr[2];        \
+    uint32_t *a_ov;           \
+                              \
+    __asm__ __volatile__      \
+    (                         \
+        "l     %0,0(15)\n\t"  \
+        "ahi   %0,96\n\t"     \
+        "stm   3,6,0(%3)\n\t" \
+        "std   0,%1\n\t"      \
+        "std   2,%2\n\t"      \
+        : "=&a" (a_ov),       \
+          "=m" (a_fpr[0]),    \
+          "=m" (a_fpr[1])     \
+        : "a" (a_gpr)         \
+       : "memory", "cc",      \
+         "3", "4", "5", "6"   \
+    );                        \
+                              \
+    return PrepareAndDispatch(this, n, a_gpr, a_fpr, a_ov); \
+}
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_linux_s390x.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_linux_s390x.cpp
new file mode 100644
index 000000000..189cceb82
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_linux_s390x.cpp
@@ -0,0 +1,187 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+static nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, 
+                   uint64_t* a_gpr, uint64_t *a_fpr, uint64_t *a_ov)
+{
+#define PARAM_BUFFER_COUNT     16
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no info");
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+    NS_ASSERTION(dispatchParams,"no place for params");
+
+    uint32_t gpr = 1, fpr = 0;
+
+    for(i = 0; i < paramCount; i++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            if (gpr < 5)
+                dp->val.p = (void*) *a_gpr++, gpr++;
+            else
+                dp->val.p = (void*) *a_ov++;
+            continue;
+        }
+        // else
+        switch(type)
+        {
+        case nsXPTType::T_I8     : 
+            if (gpr < 5)
+                dp->val.i8  = *((int64_t*) a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.i8  = *((int64_t*) a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_I16    : 
+            if (gpr < 5)
+                dp->val.i16 = *((int64_t*) a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.i16 = *((int64_t*) a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_I32    : 
+            if (gpr < 5)
+                dp->val.i32 = *((int64_t*) a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.i32 = *((int64_t*) a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_I64    : 
+            if (gpr < 5)
+                dp->val.i64 = *((int64_t*) a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.i64 = *((int64_t*) a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_U8     : 
+            if (gpr < 5)
+                dp->val.u8  = *((uint64_t*)a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.u8  = *((uint64_t*)a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_U16    : 
+            if (gpr < 5)
+                dp->val.u16 = *((uint64_t*)a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.u16 = *((uint64_t*)a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_U32    : 
+            if (gpr < 5)
+                dp->val.u32 = *((uint64_t*)a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.u32 = *((uint64_t*)a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_U64    : 
+            if (gpr < 5)
+                dp->val.u64 = *((uint64_t*)a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.u64 = *((uint64_t*)a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_FLOAT  : 
+            if (fpr < 4)
+                dp->val.f   = *((float*)   a_fpr), a_fpr++, fpr++;
+            else
+                dp->val.f   = *(((float*)  a_ov )+1), a_ov++;
+            break;
+        case nsXPTType::T_DOUBLE : 
+            if (fpr < 4)
+                dp->val.d   = *((double*)  a_fpr), a_fpr++, fpr++;
+            else
+                dp->val.d   = *((double*)  a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_BOOL   : 
+            if (gpr < 5)
+                dp->val.b   = *((uint64_t*)a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.b   = *((uint64_t*)a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_CHAR   : 
+            if (gpr < 5)
+                dp->val.c   = *((uint64_t*)a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.c   = *((uint64_t*)a_ov ), a_ov++;
+            break;
+        case nsXPTType::T_WCHAR  : 
+            if (gpr < 5)
+                dp->val.wc  = *((uint64_t*)a_gpr), a_gpr++, gpr++;
+            else
+                dp->val.wc  = *((uint64_t*)a_ov ), a_ov++;
+            break;
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+#define STUB_ENTRY(n) \
+nsresult nsXPTCStubBase::Stub##n() \
+{                             \
+    uint64_t a_gpr[4];        \
+    uint64_t a_fpr[4];        \
+    uint64_t *a_ov;           \
+                              \
+    __asm__ __volatile__      \
+    (                         \
+        "lg     %0,0(15)\n\t" \
+        "aghi   %0,160\n\t"   \
+        "stmg   3,6,0(%5)\n\t"\
+        "std    0,%1\n\t"     \
+        "std    2,%2\n\t"     \
+        "std    4,%3\n\t"     \
+        "std    6,%4\n\t"     \
+        : "=&a" (a_ov),       \
+          "=m" (a_fpr[0]),    \
+          "=m" (a_fpr[1]),    \
+          "=m" (a_fpr[2]),    \
+          "=m" (a_fpr[3])     \
+        : "a" (a_gpr)         \
+       : "memory", "cc",      \
+         "3", "4", "5", "6"   \
+    );                        \
+                              \
+    return PrepareAndDispatch(this, n, a_gpr, a_fpr, a_ov); \
+}
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_mips.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_mips.cpp
new file mode 100644
index 000000000..75f8562ce
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_mips.cpp
@@ -0,0 +1,112 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * Version: MPL 1.1
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+#include <stdint.h>
+
+/*
+ * This is for MIPS O32 ABI
+ * Args contains a0-3 and then the stack.
+ * Because a0 is 'this', we want to skip it
+ */
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint32_t* args)
+{
+    args++; // always skip over a0
+
+#define PARAM_BUFFER_COUNT		16
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no method info");
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+    NS_ASSERTION(dispatchParams,"no place for params");
+
+    uint32_t* ap = args;
+    for(i = 0; i < paramCount; i++, ap++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            dp->val.p = (void*) *ap;
+            continue;
+        }
+
+        switch(type)
+        {
+        case nsXPTType::T_I64   :
+            if ((intptr_t)ap & 4) ap++;
+            dp->val.i64 = *((int64_t*) ap); ap++;
+            break;
+        case nsXPTType::T_U64   :
+            if ((intptr_t)ap & 4) ap++;
+            dp->val.u64 = *((int64_t*) ap); ap++;
+            break;
+        case nsXPTType::T_DOUBLE:
+            if ((intptr_t)ap & 4) ap++;
+            dp->val.d   = *((double*) ap);  ap++;
+            break;
+#ifdef IS_LITTLE_ENDIAN
+        default:
+            dp->val.p = (void*) *ap;
+            break;
+#else
+        case nsXPTType::T_I8    : dp->val.i8  = (int8_t)   *ap; break;
+        case nsXPTType::T_I16   : dp->val.i16 = (int16_t)  *ap; break;
+        case nsXPTType::T_I32   : dp->val.i32 = (int32_t)  *ap; break;
+        case nsXPTType::T_U8    : dp->val.u8  = (uint8_t)  *ap; break;
+        case nsXPTType::T_U16   : dp->val.u16 = (uint16_t) *ap; break;
+        case nsXPTType::T_U32   : dp->val.u32 = (uint32_t) *ap; break;
+        case nsXPTType::T_BOOL  : dp->val.b   = (bool)   *ap; break;
+        case nsXPTType::T_CHAR  : dp->val.c   = (char)     *ap; break;
+        case nsXPTType::T_WCHAR : dp->val.wc  = (wchar_t)  *ap; break;
+        case nsXPTType::T_FLOAT : dp->val.f   = *(float *)  ap; break;
+        default:
+            NS_ASSERTION(0, "bad type");
+            break;
+#endif
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+#define STUB_ENTRY(n) // done in the .s file
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_mips64.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_mips64.cpp
new file mode 100644
index 000000000..a4b553940
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_mips64.cpp
@@ -0,0 +1,185 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+#if (_MIPS_SIM != _ABIN32) && (_MIPS_SIM != _ABI64)
+#error "This code is for MIPS n32/n64 only"
+#endif
+
+/*
+ * This is for MIPS n32/n64 ABI
+ *
+ * When we're called, the "gp" registers are stored in gprData and
+ * the "fp" registers are stored in fprData.  There are 8 regs
+ * available which correspond to the first 7 parameters of the
+ * function and the "this" pointer.  If there are additional parms,
+ * they are stored on the stack at address "args".
+ *
+ */
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint64_t* args,
+                   uint64_t *gprData, double *fprData)
+{
+#define PARAM_BUFFER_COUNT        16
+#define PARAM_GPR_COUNT            7
+#define PARAM_FPR_COUNT            7
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no method info");
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+    NS_ASSERTION(dispatchParams,"no place for params");
+
+    uint64_t* ap = args;
+    uint32_t iCount = 0;
+    for(i = 0; i < paramCount; i++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            if (iCount < PARAM_GPR_COUNT)
+                dp->val.p = (void*)gprData[iCount++];
+            else
+                dp->val.p = (void*)*ap++;
+            continue;
+        }
+        // else
+        switch(type)
+        {
+        case nsXPTType::T_I8:
+            if (iCount < PARAM_GPR_COUNT)
+                dp->val.i8  = (int8_t)gprData[iCount++];
+            else
+                dp->val.i8  = (int8_t)*ap++;
+            break;
+
+        case nsXPTType::T_I16:
+             if (iCount < PARAM_GPR_COUNT)
+                 dp->val.i16  = (int16_t)gprData[iCount++];
+             else
+                 dp->val.i16  = (int16_t)*ap++;
+             break;
+
+        case nsXPTType::T_I32:
+             if (iCount < PARAM_GPR_COUNT)
+                 dp->val.i32  = (int32_t)gprData[iCount++];
+             else
+                 dp->val.i32  = (int32_t)*ap++;
+             break;
+
+        case nsXPTType::T_I64:
+             if (iCount < PARAM_GPR_COUNT)
+                 dp->val.i64  = (int64_t)gprData[iCount++];
+             else
+                 dp->val.i64  = (int64_t)*ap++;
+             break;
+
+        case nsXPTType::T_U8:
+             if (iCount < PARAM_GPR_COUNT)
+                 dp->val.u8  = (uint8_t)gprData[iCount++];
+             else
+                 dp->val.u8  = (uint8_t)*ap++;
+             break;
+
+        case nsXPTType::T_U16:
+             if (iCount < PARAM_GPR_COUNT)
+                 dp->val.u16  = (uint16_t)gprData[iCount++];
+             else
+                  dp->val.u16  = (uint16_t)*ap++;
+             break;
+
+        case nsXPTType::T_U32:
+             if (iCount < PARAM_GPR_COUNT)
+                 dp->val.u32  = (uint32_t)gprData[iCount++];
+             else
+                 dp->val.u32  = (uint32_t)*ap++;
+             break;
+
+        case nsXPTType::T_U64:
+             if (iCount < PARAM_GPR_COUNT)
+                 dp->val.u64  = (uint64_t)gprData[iCount++];
+             else
+                 dp->val.u64  = (uint64_t)*ap++;
+             break;
+
+        case nsXPTType::T_FLOAT:
+              if (iCount < PARAM_FPR_COUNT)
+                  dp->val.f  = (double)fprData[iCount++];
+              else
+                  dp->val.f  = *((double*)ap++);
+              break;
+
+        case nsXPTType::T_DOUBLE:
+               if (iCount < PARAM_FPR_COUNT)
+                   dp->val.d  = (double)fprData[iCount++];
+               else
+                   dp->val.d  = *((double*)ap++);
+               break;
+
+        case nsXPTType::T_BOOL:
+            if (iCount < PARAM_GPR_COUNT)
+                dp->val.b  = (bool)gprData[iCount++];
+            else
+                dp->val.b  = (bool)*ap++;
+            break;
+
+        case nsXPTType::T_CHAR:
+            if (iCount < PARAM_GPR_COUNT)
+                dp->val.c  = (char)gprData[iCount++];
+            else
+                dp->val.c  = (char)*ap++;
+            break;
+
+        case nsXPTType::T_WCHAR:
+            if (iCount < PARAM_GPR_COUNT)
+                dp->val.wc  = (wchar_t)gprData[iCount++];
+            else
+                dp->val.wc  = (wchar_t)*ap++;
+            break;
+
+        default:
+            NS_ASSERTION(0, "bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+#define STUB_ENTRY(n)        /* defined in the assembly file */
+
+#define SENTINEL_ENTRY(n)                              \
+nsresult nsXPTCStubBase::Sentinel##n()                 \
+{                                                      \
+    NS_ASSERTION(0,"nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED;                   \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_netbsd_m68k.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_netbsd_m68k.cpp
new file mode 100644
index 000000000..680114fd5
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_netbsd_m68k.cpp
@@ -0,0 +1,115 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+
+#if !defined(__NetBSD__) || !defined(__m68k__)
+#error This code is for NetBSD/m68k only
+#endif
+
+extern "C" {
+    static nsresult ATTRIBUTE_USED
+    PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint32_t* args)
+    {
+#define PARAM_BUFFER_COUNT     16
+
+        nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+        nsXPTCMiniVariant* dispatchParams = nullptr;
+        nsIInterfaceInfo* iface_info = nullptr;
+        const nsXPTMethodInfo* info;
+        uint8_t paramCount;
+        uint8_t i;
+        nsresult result = NS_ERROR_FAILURE;
+
+        NS_ASSERTION(self,"no self");
+
+        self->GetInterfaceInfo(&iface_info);
+        NS_ASSERTION(iface_info,"no interface info");
+
+        iface_info->GetMethodInfo(uint16_t(methodIndex), &info);
+        NS_ASSERTION(info,"no interface info");
+
+        paramCount = info->GetParamCount();
+
+        // setup variant array pointer
+        if(paramCount > PARAM_BUFFER_COUNT)
+            dispatchParams = new nsXPTCMiniVariant[paramCount];
+        else
+            dispatchParams = paramBuffer;
+        NS_ASSERTION(dispatchParams,"no place for params");
+
+        uint32_t* ap = args;
+        for(i = 0; i < paramCount; i++, ap++)
+        {
+            const nsXPTParamInfo& param = info->GetParam(i);
+            const nsXPTType& type = param.GetType();
+            nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+            if(param.IsOut() || !type.IsArithmetic())
+            {
+                dp->val.p = (void*) *ap;
+                continue;
+            }
+
+            switch(type)
+            {
+            // the 8 and 16 bit types will have been promoted to 32 bits before
+            // being pushed onto the stack. Since the 68k is big endian, we
+            // need to skip over the leading high order bytes.
+            case nsXPTType::T_I8     : dp->val.i8  = *(((int8_t*) ap) + 3);  break;
+            case nsXPTType::T_I16    : dp->val.i16 = *(((int16_t*) ap) + 1); break;
+            case nsXPTType::T_I32    : dp->val.i32 = *((int32_t*) ap);       break;
+            case nsXPTType::T_I64    : dp->val.i64 = *((int64_t*) ap); ap++; break;
+            case nsXPTType::T_U8     : dp->val.u8  = *(((uint8_t*) ap) + 3); break;
+            case nsXPTType::T_U16    : dp->val.u16 = *(((uint16_t*)ap) + 1); break;
+            case nsXPTType::T_U32    : dp->val.u32 = *((uint32_t*)ap);       break;
+            case nsXPTType::T_U64    : dp->val.u64 = *((uint64_t*)ap); ap++; break;
+            case nsXPTType::T_FLOAT  : dp->val.f   = *((float*)   ap);       break;
+            case nsXPTType::T_DOUBLE : dp->val.d   = *((double*)  ap); ap++; break;
+            case nsXPTType::T_BOOL   : dp->val.b   = *(((char*)   ap) + 3);  break;
+            case nsXPTType::T_CHAR   : dp->val.c   = *(((char*)   ap) + 3);  break;
+            // wchar_t is an int (32 bits) on NetBSD
+            case nsXPTType::T_WCHAR  : dp->val.wc  = *((wchar_t*) ap);       break;
+            default:
+                NS_ERROR("bad type");
+                break;
+            }
+        }
+
+        result = self->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+        NS_RELEASE(iface_info);
+
+        if(dispatchParams != paramBuffer)
+            delete [] dispatchParams;
+
+        return result;
+    }
+}
+
+#define STUB_ENTRY(n)							\
+__asm__(								\
+    ".global	_Stub"#n"__14nsXPTCStubBase\n\t"			\
+"_Stub"#n"__14nsXPTCStubBase:\n\t"					\
+    "link  a6,#0			\n\t"				\
+    "lea   a6@(12), a0			\n\t"	/* pointer to args */	\
+    "movl  a0, sp@-			\n\t"				\
+    "movl  #"#n", sp@-			\n\t"	/* method index */	\
+    "movl  a6@(8), sp@-			\n\t"	/* this */		\
+    "jbsr  _PrepareAndDispatch		\n\t"				\
+    "unlk  a6				\n\t"				\
+    "rts				\n\t"				\
+);
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_pa32.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_pa32.cpp
new file mode 100644
index 000000000..7353709f1
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_pa32.cpp
@@ -0,0 +1,143 @@
+
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h" 
+
+#if _HPUX
+#error "This code is for HP-PA RISC 32 bit mode only"
+#endif
+
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex,
+  uint32_t* args, uint32_t* floatargs)
+{
+
+  typedef struct {
+    uint32_t hi;
+    uint32_t lo;
+  } DU;
+
+#define PARAM_BUFFER_COUNT     16
+
+  nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+  nsXPTCMiniVariant* dispatchParams = nullptr;
+  const nsXPTMethodInfo* info;
+  int32_t regwords = 1; /* self pointer is not in the variant records */
+  nsresult result = NS_ERROR_FAILURE;
+  uint8_t paramCount;
+  uint8_t i;
+
+  NS_ASSERTION(self,"no self");
+
+  self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+  NS_ASSERTION(info,"no method info");
+  if (!info)
+    return NS_ERROR_UNEXPECTED;
+
+  paramCount = info->GetParamCount();
+
+  // setup variant array pointer
+  if(paramCount > PARAM_BUFFER_COUNT)
+    dispatchParams = new nsXPTCMiniVariant[paramCount];
+  else
+    dispatchParams = paramBuffer;
+  NS_ASSERTION(dispatchParams,"no place for params");
+  if (!dispatchParams)
+    return NS_ERROR_OUT_OF_MEMORY;
+
+  for(i = 0; i < paramCount; ++i, --args)
+  {
+    const nsXPTParamInfo& param = info->GetParam(i);
+    const nsXPTType& type = param.GetType();
+    nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+    if(param.IsOut() || !type.IsArithmetic())
+    {
+      dp->val.p = (void*) *args;
+      ++regwords;
+      continue;
+    }
+    switch(type)
+    {
+    case nsXPTType::T_I8     : dp->val.i8  = *((int32_t*) args); break;
+    case nsXPTType::T_I16    : dp->val.i16 = *((int32_t*) args); break;
+    case nsXPTType::T_I32    : dp->val.i32 = *((int32_t*) args); break;
+    case nsXPTType::T_DOUBLE :
+                               if (regwords & 1)
+                               {
+                                 ++regwords; /* align on double word */
+                                 --args;
+                               }
+                               if (regwords == 0 || regwords == 2)
+                               {
+                                 dp->val.d=*((double*) (floatargs + regwords));
+                                 --args;
+                               }
+                               else
+                               {
+                                 dp->val.d = *((double*) --args);
+                               }
+                               regwords += 2;
+                               continue;
+    case nsXPTType::T_U64    :
+    case nsXPTType::T_I64    :
+                               if (regwords & 1)
+                               {
+                                 ++regwords; /* align on double word */
+                                 --args;
+                               }
+                               ((DU *)dp)->lo = *((uint32_t*) args);
+                               ((DU *)dp)->hi = *((uint32_t*) --args);
+                               regwords += 2;
+                               continue;
+    case nsXPTType::T_FLOAT  :
+                               if (regwords >= 4)
+                                 dp->val.f = *((float*) args);
+                               else
+                                 dp->val.f = *((float*) floatargs+4+regwords);
+                               break;
+    case nsXPTType::T_U8     : dp->val.u8  = *((uint32_t*) args); break;
+    case nsXPTType::T_U16    : dp->val.u16 = *((uint32_t*) args); break;
+    case nsXPTType::T_U32    : dp->val.u32 = *((uint32_t*) args); break;
+    case nsXPTType::T_BOOL   : dp->val.b   = *((uint32_t*) args); break;
+    case nsXPTType::T_CHAR   : dp->val.c   = *((uint32_t*) args); break;
+    case nsXPTType::T_WCHAR  : dp->val.wc  = *((int32_t*)  args); break;
+    default:
+      NS_ERROR("bad type");
+      break;
+    }
+    ++regwords;
+  }
+
+  result = self->mOuter->CallMethod((uint16_t) methodIndex, info, dispatchParams); 
+
+  if(dispatchParams != paramBuffer)
+    delete [] dispatchParams;
+
+  return result;
+}
+
+extern "C" nsresult SharedStub(int);
+
+#define STUB_ENTRY(n)       \
+nsresult nsXPTCStubBase::Stub##n()  \
+{                           \
+    return SharedStub(n);   \
+}
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
+
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc64_linux.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc64_linux.cpp
new file mode 100644
index 000000000..95e67cb29
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc64_linux.cpp
@@ -0,0 +1,246 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Implement shared vtbl methods.
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+// The Linux/PPC64 ABI passes the first 8 integral
+// parameters and the first 13 floating point parameters in registers
+// (r3-r10 and f1-f13), no stack space is allocated for these by the
+// caller.  The rest of the parameters are passed in the caller's stack
+// area. The stack pointer has to retain 16-byte alignment.
+
+// The PowerPC64 platform ABI can be found here:
+// http://www.freestandards.org/spec/ELF/ppc64/
+// and in particular:
+// http://www.freestandards.org/spec/ELF/ppc64/PPC-elf64abi-1.9.html#FUNC-CALL
+
+#define PARAM_BUFFER_COUNT      16
+#define GPR_COUNT                7
+#define FPR_COUNT               13
+
+// PrepareAndDispatch() is called by SharedStub() and calls the actual method.
+//
+// - 'args[]' contains the arguments passed on stack
+// - 'gprData[]' contains the arguments passed in integer registers
+// - 'fprData[]' contains the arguments passed in floating point registers
+// 
+// The parameters are mapped into an array of type 'nsXPTCMiniVariant'
+// and then the method gets called.
+#include <stdio.h>
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self,
+                   uint64_t methodIndex,
+                   uint64_t* args,
+                   uint64_t *gprData,
+                   double *fprData)
+{
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info;
+    uint32_t paramCount;
+    uint32_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no method info");
+    if (! info)
+        return NS_ERROR_UNEXPECTED;
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+
+    NS_ASSERTION(dispatchParams,"no place for params");
+    if (! dispatchParams)
+        return NS_ERROR_OUT_OF_MEMORY;
+
+    uint64_t* ap = args;
+    uint64_t tempu64;
+
+    for(i = 0; i < paramCount; i++) {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+	
+        if (!param.IsOut() && type == nsXPTType::T_DOUBLE) {
+            if (i < FPR_COUNT)
+                dp->val.d = fprData[i];
+            else
+                dp->val.d = *(double*) ap;
+        } else if (!param.IsOut() && type == nsXPTType::T_FLOAT) {
+            if (i < FPR_COUNT)
+                dp->val.f = (float) fprData[i]; // in registers floats are passed as doubles
+            else {
+                float *p = (float *)ap;
+#ifndef __LITTLE_ENDIAN__
+                p++;
+#endif
+                dp->val.f = *p;
+            }
+        } else { /* integer type or pointer */
+            if (i < GPR_COUNT)
+                tempu64 = gprData[i];
+            else
+                tempu64 = *ap;
+
+            if (param.IsOut() || !type.IsArithmetic())
+                dp->val.p = (void*) tempu64;
+            else if (type == nsXPTType::T_I8)
+                dp->val.i8  = (int8_t)   tempu64;
+            else if (type == nsXPTType::T_I16)
+                dp->val.i16 = (int16_t)  tempu64;
+            else if (type == nsXPTType::T_I32)
+                dp->val.i32 = (int32_t)  tempu64;
+            else if (type == nsXPTType::T_I64)
+                dp->val.i64 = (int64_t)  tempu64;
+            else if (type == nsXPTType::T_U8)
+                dp->val.u8  = (uint8_t)  tempu64;
+            else if (type == nsXPTType::T_U16)
+                dp->val.u16 = (uint16_t) tempu64;
+            else if (type == nsXPTType::T_U32)
+                dp->val.u32 = (uint32_t) tempu64;
+            else if (type == nsXPTType::T_U64)
+                dp->val.u64 = (uint64_t) tempu64;
+            else if (type == nsXPTType::T_BOOL)
+                dp->val.b   = (bool)   tempu64;
+            else if (type == nsXPTType::T_CHAR)
+                dp->val.c   = (char)     tempu64;
+            else if (type == nsXPTType::T_WCHAR)
+                dp->val.wc  = (wchar_t)  tempu64;
+            else
+                NS_ERROR("bad type");
+        }
+
+        if (i >= 7)
+            ap++;
+    }
+
+    result = self->mOuter->CallMethod((uint16_t) methodIndex, info,
+                                      dispatchParams);
+
+    if (dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+// Load r11 with the constant 'n' and branch to SharedStub().
+//
+// XXX Yes, it's ugly that we're relying on gcc's name-mangling here;
+// however, it's quick, dirty, and'll break when the ABI changes on
+// us, which is what we want ;-).
+
+
+// gcc-3 version
+//
+// As G++3 ABI contains the length of the functionname in the mangled
+// name, it is difficult to get a generic assembler mechanism like
+// in the G++ 2.95 case.
+// Create names would be like:
+// _ZN14nsXPTCStubBase5Stub1Ev
+// _ZN14nsXPTCStubBase6Stub12Ev
+// _ZN14nsXPTCStubBase7Stub123Ev
+// _ZN14nsXPTCStubBase8Stub1234Ev
+// etc.
+// Use assembler directives to get the names right...
+
+#if _CALL_ELF == 2
+# define STUB_ENTRY(n)                                                  \
+__asm__ (                                                               \
+        ".section \".text\" \n\t"                                       \
+        ".align 2 \n\t"                                                 \
+        ".if "#n" < 10 \n\t"                                            \
+        ".globl _ZN14nsXPTCStubBase5Stub"#n"Ev \n\t"                    \
+        ".type  _ZN14nsXPTCStubBase5Stub"#n"Ev,@function \n\n"          \
+"_ZN14nsXPTCStubBase5Stub"#n"Ev: \n\t"                                  \
+        "0: addis 2,12,.TOC.-0b@ha \n\t"                                \
+        "addi     2,2,.TOC.-0b@l \n\t"                                  \
+        ".localentry _ZN14nsXPTCStubBase5Stub"#n"Ev,.-_ZN14nsXPTCStubBase5Stub"#n"Ev \n\t" \
+                                                                        \
+        ".elseif "#n" < 100 \n\t"                                       \
+        ".globl _ZN14nsXPTCStubBase6Stub"#n"Ev \n\t"                    \
+        ".type  _ZN14nsXPTCStubBase6Stub"#n"Ev,@function \n\n"          \
+"_ZN14nsXPTCStubBase6Stub"#n"Ev: \n\t"                                  \
+        "0: addis 2,12,.TOC.-0b@ha \n\t"                                \
+        "addi     2,2,.TOC.-0b@l \n\t"                                  \
+        ".localentry _ZN14nsXPTCStubBase6Stub"#n"Ev,.-_ZN14nsXPTCStubBase6Stub"#n"Ev \n\t" \
+                                                                        \
+        ".elseif "#n" < 1000 \n\t"                                      \
+        ".globl _ZN14nsXPTCStubBase7Stub"#n"Ev \n\t"                    \
+        ".type  _ZN14nsXPTCStubBase7Stub"#n"Ev,@function \n\n"          \
+"_ZN14nsXPTCStubBase7Stub"#n"Ev: \n\t"                                  \
+        "0: addis 2,12,.TOC.-0b@ha \n\t"                                \
+        "addi     2,2,.TOC.-0b@l \n\t"                                  \
+        ".localentry _ZN14nsXPTCStubBase7Stub"#n"Ev,.-_ZN14nsXPTCStubBase7Stub"#n"Ev \n\t" \
+                                                                        \
+        ".else  \n\t"                                                   \
+        ".err   \"stub number "#n" >= 1000 not yet supported\"\n"       \
+        ".endif \n\t"                                                   \
+                                                                        \
+        "li     11,"#n" \n\t"                                           \
+        "b      SharedStub \n"                                          \
+);
+#else
+# define STUB_ENTRY(n)                                                  \
+__asm__ (                                                               \
+        ".section \".toc\",\"aw\" \n\t"                                 \
+        ".section \".text\" \n\t"                                       \
+        ".align 2 \n\t"                                                 \
+        ".if "#n" < 10 \n\t"                                            \
+        ".globl _ZN14nsXPTCStubBase5Stub"#n"Ev \n\t"                    \
+        ".section \".opd\",\"aw\" \n\t"                                 \
+        ".align 3 \n\t"                                                 \
+"_ZN14nsXPTCStubBase5Stub"#n"Ev: \n\t"                                  \
+        ".quad  ._ZN14nsXPTCStubBase5Stub"#n"Ev,.TOC.@tocbase \n\t"     \
+        ".previous \n\t"                                                \
+        ".type  _ZN14nsXPTCStubBase5Stub"#n"Ev,@function \n\n"          \
+"._ZN14nsXPTCStubBase5Stub"#n"Ev: \n\t"                                 \
+                                                                        \
+        ".elseif "#n" < 100 \n\t"                                       \
+        ".globl _ZN14nsXPTCStubBase6Stub"#n"Ev \n\t"                    \
+        ".section \".opd\",\"aw\" \n\t"                                 \
+        ".align 3 \n\t"                                                 \
+"_ZN14nsXPTCStubBase6Stub"#n"Ev: \n\t"                                  \
+        ".quad  ._ZN14nsXPTCStubBase6Stub"#n"Ev,.TOC.@tocbase \n\t"     \
+        ".previous \n\t"                                                \
+        ".type  _ZN14nsXPTCStubBase6Stub"#n"Ev,@function \n\n"          \
+"._ZN14nsXPTCStubBase6Stub"#n"Ev: \n\t"                                 \
+                                                                        \
+        ".elseif "#n" < 1000 \n\t"                                      \
+        ".globl _ZN14nsXPTCStubBase7Stub"#n"Ev \n\t"                    \
+        ".section \".opd\",\"aw\" \n\t"                                 \
+        ".align 3 \n\t"                                                 \
+"_ZN14nsXPTCStubBase7Stub"#n"Ev: \n\t"                                  \
+        ".quad  ._ZN14nsXPTCStubBase7Stub"#n"Ev,.TOC.@tocbase \n\t"     \
+        ".previous \n\t"                                                \
+        ".type  _ZN14nsXPTCStubBase7Stub"#n"Ev,@function \n\n"          \
+"._ZN14nsXPTCStubBase7Stub"#n"Ev: \n\t"                                 \
+                                                                        \
+        ".else  \n\t"                                                   \
+        ".err   \"stub number "#n" >= 1000 not yet supported\"\n"       \
+        ".endif \n\t"                                                   \
+                                                                        \
+        "li     11,"#n" \n\t"                                           \
+        "b      SharedStub \n"                                          \
+);
+#endif
+
+#define SENTINEL_ENTRY(n)                                               \
+nsresult nsXPTCStubBase::Sentinel##n()                                  \
+{                                                                       \
+    NS_ERROR("nsXPTCStubBase::Sentinel called");                  \
+    return NS_ERROR_NOT_IMPLEMENTED;                                    \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_aix.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_aix.cpp
new file mode 100644
index 000000000..0463c21c5
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_aix.cpp
@@ -0,0 +1,185 @@
+/* -*- Mode: C; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+#if defined(AIX)
+
+/*
+        For PPC (AIX & MAC), the first 8 integral and the first 13 f.p. parameters 
+        arrive in a separate chunk of data that has been loaded from the registers. 
+        The args pointer has been set to the start of the parameters BEYOND the ones
+        arriving in registers
+*/
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint32_t* args, uint32_t *gprData, double *fprData)
+{
+    typedef struct {
+        uint32_t hi;
+        uint32_t lo;      // have to move 64 bit entities as 32 bit halves since
+    } DU;               // stack slots are not guaranteed 16 byte aligned
+
+#define PARAM_BUFFER_COUNT     16
+#define PARAM_GPR_COUNT         7  
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info = nullptr;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no method info");
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+    NS_ASSERTION(dispatchParams,"no place for params");
+
+    uint32_t* ap = args;
+    uint32_t iCount = 0;
+    uint32_t fpCount = 0;
+    for(i = 0; i < paramCount; i++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            if (iCount < PARAM_GPR_COUNT)
+                dp->val.p = (void*) gprData[iCount++];
+            else
+                dp->val.p = (void*) *ap++;
+            continue;
+        }
+        // else
+        switch(type)
+        {
+        case nsXPTType::T_I8      :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.i8  = (int8_t) gprData[iCount++];
+                                     else
+                                         dp->val.i8  = (int8_t)  *ap++;
+                                     break;
+        case nsXPTType::T_I16     :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.i16  = (int16_t) gprData[iCount++];
+                                     else
+                                         dp->val.i16  = (int16_t)  *ap++;
+                                     break;
+        case nsXPTType::T_I32     :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.i32  = (int32_t) gprData[iCount++];
+                                     else
+                                         dp->val.i32  = (int32_t)  *ap++;
+                                     break;
+        case nsXPTType::T_I64     :  if (iCount < PARAM_GPR_COUNT)
+                                         ((DU *)dp)->hi  = (int32_t) gprData[iCount++];
+                                     else
+                                         ((DU *)dp)->hi  = (int32_t)  *ap++;
+                                     if (iCount < PARAM_GPR_COUNT)
+                                         ((DU *)dp)->lo  = (uint32_t) gprData[iCount++];
+                                     else
+                                         ((DU *)dp)->lo  = (uint32_t)  *ap++;
+                                     break;
+        case nsXPTType::T_U8      :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.u8  = (uint8_t) gprData[iCount++];
+                                     else
+                                         dp->val.u8  = (uint8_t)  *ap++;
+                                     break;
+        case nsXPTType::T_U16     :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.u16  = (uint16_t) gprData[iCount++];
+                                     else
+                                         dp->val.u16  = (uint16_t)  *ap++;
+                                     break;
+        case nsXPTType::T_U32     :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.u32  = (uint32_t) gprData[iCount++];
+                                     else
+                                         dp->val.u32  = (uint32_t)  *ap++;
+                                     break;
+        case nsXPTType::T_U64     :  if (iCount < PARAM_GPR_COUNT)
+                                         ((DU *)dp)->hi  = (uint32_t) gprData[iCount++];
+                                     else
+                                         ((DU *)dp)->hi  = (uint32_t)  *ap++;
+                                     if (iCount < PARAM_GPR_COUNT)
+                                         ((DU *)dp)->lo  = (uint32_t) gprData[iCount++];
+                                     else
+                                         ((DU *)dp)->lo  = (uint32_t)  *ap++;
+                                     break;
+        case nsXPTType::T_FLOAT   :  if (fpCount < 13) {
+                                         dp->val.f  = (float) fprData[fpCount++];
+                                         if (iCount < PARAM_GPR_COUNT)
+                                             ++iCount;
+                                         else
+                                             ++ap;
+                                     }
+                                     else
+                                         dp->val.f   = *((float*)   ap++);
+                                     break;
+        case nsXPTType::T_DOUBLE  :  if (fpCount < 13) {
+                                         dp->val.d  = (double) fprData[fpCount++];
+                                         if (iCount < PARAM_GPR_COUNT)
+                                             ++iCount;
+                                         else
+                                             ++ap;
+                                         if (iCount < PARAM_GPR_COUNT)
+                                             ++iCount;
+                                         else
+                                             ++ap;
+                                     }
+                                     else {
+                                         dp->val.f   = *((double*)   ap);
+                                         ap += 2;
+                                     }
+                                     break;
+        case nsXPTType::T_BOOL    :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.b  = (bool) gprData[iCount++];
+                                     else
+                                         dp->val.b  = (bool)  *ap++;
+                                     break;
+        case nsXPTType::T_CHAR    :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.c  = (char) gprData[iCount++];
+                                     else
+                                         dp->val.c  = (char)  *ap++;
+                                     break;
+        case nsXPTType::T_WCHAR   :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.wc  = (wchar_t) gprData[iCount++];
+                                     else
+                                         dp->val.wc  = (wchar_t)  *ap++;
+                                     break;
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex,info,dispatchParams);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+#define STUB_ENTRY(n)
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
+
+#endif /* AIX */
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_aix64.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_aix64.cpp
new file mode 100644
index 000000000..08eb557ab
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_aix64.cpp
@@ -0,0 +1,172 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+#if defined(AIX)
+
+/*
+        For PPC (AIX & MAC), the first 8 integral and the first 13 f.p. parameters 
+        arrive in a separate chunk of data that has been loaded from the registers. 
+        The args pointer has been set to the start of the parameters BEYOND the ones
+        arriving in registers
+*/
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self, uint64_t methodIndex, uint64_t* args, uint64_t *gprData, double *fprData)
+{
+
+#define PARAM_BUFFER_COUNT     16
+#define PARAM_GPR_COUNT         7  
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info = nullptr;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no method info");
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+    NS_ASSERTION(dispatchParams,"no place for params");
+
+    uint64_t* ap = args;
+    uint32_t iCount = 0;
+    uint32_t fpCount = 0;
+    for(i = 0; i < paramCount; i++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            if (iCount < PARAM_GPR_COUNT)
+                dp->val.p = (void*) gprData[iCount++];
+            else
+                dp->val.p = (void*) *ap++;
+            continue;
+        }
+        // else
+        switch(type)
+        {
+        case nsXPTType::T_I8      :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.i8  = (int8_t) gprData[iCount++];
+                                     else
+                                         dp->val.i8  = (int8_t)  *ap++;
+                                     break;
+        case nsXPTType::T_I16     :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.i16  = (int16_t) gprData[iCount++];
+                                     else
+                                         dp->val.i16  = (int16_t)  *ap++;
+                                     break;
+        case nsXPTType::T_I32     :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.i32  = (int32_t) gprData[iCount++];
+                                     else
+                                         dp->val.i32  = (int32_t)  *ap++;
+                                     break;
+        case nsXPTType::T_I64     :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.i64  = (int64_t) gprData[iCount++];
+                                     else
+                                         dp->val.i64  = (int64_t) *ap++;
+                                     break;
+        case nsXPTType::T_U8      :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.u8  = (uint8_t) gprData[iCount++];
+                                     else
+                                         dp->val.u8  = (uint8_t)  *ap++;
+                                     break;
+        case nsXPTType::T_U16     :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.u16  = (uint16_t) gprData[iCount++];
+                                     else
+                                         dp->val.u16  = (uint16_t)  *ap++;
+                                     break;
+        case nsXPTType::T_U32     :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.u32  = (uint32_t) gprData[iCount++];
+                                     else
+                                         dp->val.u32  = (uint32_t)  *ap++;
+                                     break;
+        case nsXPTType::T_U64     :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.u64  = (uint64_t) gprData[iCount++];
+                                     else
+                                         dp->val.u64  = (uint64_t)  *ap++;
+                                     break;
+        case nsXPTType::T_FLOAT   :  if (fpCount < 13) {
+                                         dp->val.f  = (float) fprData[fpCount++];
+                                         if (iCount < PARAM_GPR_COUNT)
+                                             ++iCount;
+                                         else
+                                             ++ap;
+                                     }
+                                     else
+                                         dp->val.f   = *((float*)   ap++);
+                                     break;
+        case nsXPTType::T_DOUBLE  :  if (fpCount < 13) {
+                                         dp->val.d  = (double) fprData[fpCount++];
+                                         if (iCount < PARAM_GPR_COUNT)
+                                             ++iCount;
+                                         else
+                                             ++ap;
+                                         if (iCount < PARAM_GPR_COUNT)
+                                             ++iCount;
+                                         else
+                                             ++ap;
+                                     }
+                                     else {
+                                         dp->val.f   = *((double*)   ap);
+                                         ap += 2;
+                                     }
+                                     break;
+        case nsXPTType::T_BOOL    :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.b  = (bool) gprData[iCount++];
+                                     else
+                                         dp->val.b  = (bool)  *ap++;
+                                     break;
+        case nsXPTType::T_CHAR    :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.c  = (char) gprData[iCount++];
+                                     else
+                                         dp->val.c  = (char)  *ap++;
+                                     break;
+        case nsXPTType::T_WCHAR   :  if (iCount < PARAM_GPR_COUNT)
+                                         dp->val.wc  = (wchar_t) gprData[iCount++];
+                                     else
+                                         dp->val.wc  = (wchar_t)  *ap++;
+                                     break;
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex,info,dispatchParams);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+#define STUB_ENTRY(n)
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
+
+#endif /* AIX */
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_linux.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_linux.cpp
new file mode 100644
index 000000000..86405a8ca
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_linux.cpp
@@ -0,0 +1,220 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Implement shared vtbl methods.
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+// The Linux/PPC ABI (aka PPC/SYSV ABI) passes the first 8 integral
+// parameters and the first 8 floating point parameters in registers
+// (r3-r10 and f1-f8), no stack space is allocated for these by the
+// caller.  The rest of the parameters are passed in the callers stack
+// area. The stack pointer has to retain 16-byte alignment, longlongs
+// and doubles are aligned on 8-byte boundaries.
+#ifndef __NO_FPRS__
+#define PARAM_BUFFER_COUNT     16
+#define GPR_COUNT               8
+#define FPR_COUNT               8
+#else
+#define PARAM_BUFFER_COUNT      8
+#define GPR_COUNT               8
+#endif
+// PrepareAndDispatch() is called by SharedStub() and calls the actual method.
+//
+// - 'args[]' contains the arguments passed on stack
+// - 'gprData[]' contains the arguments passed in integer registers
+// - 'fprData[]' contains the arguments passed in floating point registers
+// 
+// The parameters are mapped into an array of type 'nsXPTCMiniVariant'
+// and then the method gets called.
+
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self,
+                   uint32_t methodIndex,
+                   uint32_t* args,
+                   uint32_t *gprData,
+                   double *fprData)
+{
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info = nullptr;
+    uint32_t paramCount;
+    uint32_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no method info");
+    if (! info)
+        return NS_ERROR_UNEXPECTED;
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+
+    NS_ASSERTION(dispatchParams,"no place for params");
+    if (! dispatchParams)
+        return NS_ERROR_OUT_OF_MEMORY;
+
+    uint32_t* ap = args;
+    uint32_t gpr = 1;    // skip one GPR register
+#ifndef __NO_FPRS__
+    uint32_t fpr = 0;
+#endif
+    uint32_t tempu32;
+    uint64_t tempu64;
+
+    for(i = 0; i < paramCount; i++) {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+	
+        if (!param.IsOut() && type == nsXPTType::T_DOUBLE) {
+#ifndef __NO_FPRS__
+            if (fpr < FPR_COUNT)
+                dp->val.d = fprData[fpr++];
+#else
+            if (gpr & 1)
+                gpr++;
+            if (gpr + 1 < GPR_COUNT) {
+                dp->val.d = *(double*) &gprData[gpr];
+                gpr += 2;
+            }
+#endif
+            else {
+                if ((uint32_t) ap & 4) ap++; // doubles are 8-byte aligned on stack
+                dp->val.d = *(double*) ap;
+                ap += 2;
+            }
+            continue;
+        }
+        else if (!param.IsOut() && type == nsXPTType::T_FLOAT) {
+#ifndef __NO_FPRS__
+            if (fpr < FPR_COUNT)
+                dp->val.f = (float) fprData[fpr++]; // in registers floats are passed as doubles
+#else
+            if (gpr  < GPR_COUNT)
+                dp->val.f = *(float*) &gprData[gpr++];
+#endif
+            else
+                dp->val.f = *(float*) ap++;
+            continue;
+        }
+        else if (!param.IsOut() && (type == nsXPTType::T_I64
+                                    || type == nsXPTType::T_U64)) {
+            if (gpr & 1) gpr++; // longlongs are aligned in odd/even register pairs, eg. r5/r6
+            if ((gpr + 1) < GPR_COUNT) {
+                tempu64 = *(uint64_t*) &gprData[gpr];
+                gpr += 2;
+            }
+            else {
+                if ((uint32_t) ap & 4) ap++; // longlongs are 8-byte aligned on stack
+                tempu64 = *(uint64_t*) ap;
+                ap += 2;
+            }
+        }
+        else {
+            if (gpr < GPR_COUNT)
+                tempu32 = gprData[gpr++];
+            else
+                tempu32 = *ap++;
+        }
+
+        if(param.IsOut() || !type.IsArithmetic()) {
+            if (type == nsXPTType::T_JSVAL)
+                dp->val.p = *((void**) tempu32);
+            else
+                dp->val.p = (void*) tempu32;
+            continue;
+        }
+
+        switch(type) {
+        case nsXPTType::T_I8:      dp->val.i8  = (int8_t)   tempu32; break;
+        case nsXPTType::T_I16:     dp->val.i16 = (int16_t)  tempu32; break;
+        case nsXPTType::T_I32:     dp->val.i32 = (int32_t)  tempu32; break;
+        case nsXPTType::T_I64:     dp->val.i64 = (int64_t)  tempu64; break;
+        case nsXPTType::T_U8:      dp->val.u8  = (uint8_t)  tempu32; break;
+        case nsXPTType::T_U16:     dp->val.u16 = (uint16_t) tempu32; break;
+        case nsXPTType::T_U32:     dp->val.u32 = (uint32_t) tempu32; break;
+        case nsXPTType::T_U64:     dp->val.u64 = (uint64_t) tempu64; break;
+        case nsXPTType::T_BOOL:    dp->val.b   = (bool)     tempu32; break;
+        case nsXPTType::T_CHAR:    dp->val.c   = (char)     tempu32; break;
+        case nsXPTType::T_WCHAR:   dp->val.wc  = (wchar_t)  tempu32; break;
+
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex,
+                                      info,
+                                      dispatchParams);
+
+    if (dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+// Load r11 with the constant 'n' and branch to SharedStub().
+//
+// XXX Yes, it's ugly that we're relying on gcc's name-mangling here;
+// however, it's quick, dirty, and'll break when the ABI changes on
+// us, which is what we want ;-).
+
+// gcc-3 version
+//
+// As G++3 ABI contains the length of the functionname in the mangled
+// name, it is difficult to get a generic assembler mechanism like
+// in the G++ 2.95 case.
+// Create names would be like:
+// _ZN14nsXPTCStubBase5Stub1Ev
+// _ZN14nsXPTCStubBase6Stub12Ev
+// _ZN14nsXPTCStubBase7Stub123Ev
+// _ZN14nsXPTCStubBase8Stub1234Ev
+// etc.
+// Use assembler directives to get the names right...
+
+# define STUB_ENTRY(n)							\
+__asm__ (								\
+	".align	2 \n\t"							\
+	".if	"#n" < 10 \n\t"						\
+	".globl	_ZN14nsXPTCStubBase5Stub"#n"Ev \n\t"			\
+	".type	_ZN14nsXPTCStubBase5Stub"#n"Ev,@function \n\n"		\
+"_ZN14nsXPTCStubBase5Stub"#n"Ev: \n\t"					\
+									\
+	".elseif "#n" < 100 \n\t"					\
+	".globl	_ZN14nsXPTCStubBase6Stub"#n"Ev \n\t"			\
+	".type	_ZN14nsXPTCStubBase6Stub"#n"Ev,@function \n\n"		\
+"_ZN14nsXPTCStubBase6Stub"#n"Ev: \n\t"					\
+									\
+	".elseif "#n" < 1000 \n\t"					\
+	".globl	_ZN14nsXPTCStubBase7Stub"#n"Ev \n\t"			\
+	".type	_ZN14nsXPTCStubBase7Stub"#n"Ev,@function \n\n"		\
+"_ZN14nsXPTCStubBase7Stub"#n"Ev: \n\t"					\
+									\
+	".else \n\t"							\
+	".err	\"stub number "#n" >= 1000 not yet supported\"\n"	\
+	".endif \n\t"							\
+									\
+	"li	11,"#n" \n\t"						\
+	"b	SharedStub@local \n"					\
+);
+
+#define SENTINEL_ENTRY(n)                            \
+nsresult nsXPTCStubBase::Sentinel##n()               \
+{                                                    \
+  NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+  return NS_ERROR_NOT_IMPLEMENTED;                   \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_netbsd.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_netbsd.cpp
new file mode 100644
index 000000000..ec359fc99
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_netbsd.cpp
@@ -0,0 +1,185 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Implement shared vtbl methods.
+
+#include "xptcprivate.h"
+
+// The Linux/PPC ABI (aka PPC/SYSV ABI) passes the first 8 integral
+// parameters and the first 8 floating point parameters in registers
+// (r3-r10 and f1-f8), no stack space is allocated for these by the
+// caller.  The rest of the parameters are passed in the callers stack
+// area. The stack pointer has to retain 16-byte alignment, longlongs
+// and doubles are aligned on 8-byte boundaries.
+
+#define PARAM_BUFFER_COUNT     16
+#define GPR_COUNT               8
+#define FPR_COUNT               8
+
+// PrepareAndDispatch() is called by SharedStub() and calls the actual method.
+//
+// - 'args[]' contains the arguments passed on stack
+// - 'gprData[]' contains the arguments passed in integer registers
+// - 'fprData[]' contains the arguments passed in floating point registers
+// 
+// The parameters are mapped into an array of type 'nsXPTCMiniVariant'
+// and then the method gets called.
+
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self,
+                   uint32_t methodIndex,
+                   uint32_t* args,
+                   uint32_t *gprData,
+                   double *fprData)
+{
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    nsIInterfaceInfo* iface_info = nullptr;
+    const nsXPTMethodInfo* info;
+    uint32_t paramCount;
+    uint32_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->GetInterfaceInfo(&iface_info);
+    NS_ASSERTION(iface_info,"no interface info");
+    if (! iface_info)
+        return NS_ERROR_UNEXPECTED;
+
+    iface_info->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no method info");
+    if (! info)
+        return NS_ERROR_UNEXPECTED;
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+
+    NS_ASSERTION(dispatchParams,"no place for params");
+    if (! dispatchParams)
+        return NS_ERROR_OUT_OF_MEMORY;
+
+    uint32_t* ap = args;
+    uint32_t gpr = 1;    // skip one GPR register
+    uint32_t fpr = 0;
+    uint32_t tempu32;
+    uint64_t tempu64;
+
+    for(i = 0; i < paramCount; i++) {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+	
+        if (!param.IsOut() && type == nsXPTType::T_DOUBLE) {
+            if (fpr < FPR_COUNT)
+                dp->val.d = fprData[fpr++];
+            else {
+                if ((uint32_t) ap & 4) ap++; // doubles are 8-byte aligned on stack
+                dp->val.d = *(double*) ap;
+                ap += 2;
+		if (gpr < GPR_COUNT)
+		    gpr += 2;
+            }
+            continue;
+        }
+        else if (!param.IsOut() && type == nsXPTType::T_FLOAT) {
+            if (fpr < FPR_COUNT)
+                dp->val.f = (float) fprData[fpr++]; // in registers floats are passed as doubles
+            else {
+                dp->val.f = *(float*) ap;
+		ap += 1;
+		if (gpr < GPR_COUNT)
+		    gpr += 1;
+            }
+            continue;
+        }
+        else if (!param.IsOut() && (type == nsXPTType::T_I64
+                                    || type == nsXPTType::T_U64)) {
+            if (gpr & 1) gpr++; // longlongs are aligned in odd/even register pairs, eg. r5/r6
+            if ((gpr + 1) < GPR_COUNT) {
+                tempu64 = *(uint64_t*) &gprData[gpr];
+                gpr += 2;
+            }
+            else {
+                if ((uint32_t) ap & 4) ap++; // longlongs are 8-byte aligned on stack
+                tempu64 = *(uint64_t*) ap;
+                ap += 2;
+            }
+        }
+        else {
+            if (gpr < GPR_COUNT)
+                tempu32 = gprData[gpr++];
+            else
+                tempu32 = *ap++;
+        }
+
+        if(param.IsOut() || !type.IsArithmetic()) {
+            if (type == nsXPTType::T_JSVAL)
+                dp->val.p = *((void**) tempu32);
+            else
+                dp->val.p = (void*) tempu32;
+            continue;
+        }
+
+        switch(type) {
+        case nsXPTType::T_I8:      dp->val.i8  = (int8_t)   tempu32; break;
+        case nsXPTType::T_I16:     dp->val.i16 = (int16_t)  tempu32; break;
+        case nsXPTType::T_I32:     dp->val.i32 = (int32_t)  tempu32; break;
+        case nsXPTType::T_I64:     dp->val.i64 = (int64_t)  tempu64; break;
+        case nsXPTType::T_U8:      dp->val.u8  = (uint8_t)  tempu32; break;
+        case nsXPTType::T_U16:     dp->val.u16 = (uint16_t) tempu32; break;
+        case nsXPTType::T_U32:     dp->val.u32 = (uint32_t) tempu32; break;
+        case nsXPTType::T_U64:     dp->val.u64 = (uint64_t) tempu64; break;
+        case nsXPTType::T_BOOL:    dp->val.b   = (bool)     tempu32; break;
+        case nsXPTType::T_CHAR:    dp->val.c   = (char)     tempu32; break;
+        case nsXPTType::T_WCHAR:   dp->val.wc  = (wchar_t)  tempu32; break;
+
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->CallMethod((uint16_t) methodIndex, info, dispatchParams);
+
+    NS_RELEASE(iface_info);
+
+    if (dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+// Load r11 with the constant 'n' and branch to SharedStub().
+//
+// XXX Yes, it's ugly that we're relying on gcc's name-mangling here;
+// however, it's quick, dirty, and'll break when the ABI changes on
+// us, which is what we want ;-).
+
+#define STUB_ENTRY(n)                                       \
+__asm__ (                                                   \
+        ".section \".text\" \n\t"                           \
+        ".align 2 \n\t"                                     \
+	".globl  Stub"#n"__14nsXPTCStubBase \n\t"           \
+	".type   Stub"#n"__14nsXPTCStubBase,@function \n\n" \
+                                                            \
+"Stub"#n"__14nsXPTCStubBase: \n\t"                          \
+	"li     11,"#n" \n\t"                               \
+	"b      SharedStub@local \n"                        \
+);
+
+#define SENTINEL_ENTRY(n)                            \
+nsresult nsXPTCStubBase::Sentinel##n()               \
+{                                                    \
+  NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+  return NS_ERROR_NOT_IMPLEMENTED;                   \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_openbsd.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_openbsd.cpp
new file mode 100644
index 000000000..62a693643
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_openbsd.cpp
@@ -0,0 +1,202 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Implement shared vtbl methods.
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+// The Linux/PPC ABI (aka PPC/SYSV ABI) passes the first 8 integral
+// parameters and the first 8 floating point parameters in registers
+// (r3-r10 and f1-f8), no stack space is allocated for these by the
+// caller.  The rest of the parameters are passed in the callers stack
+// area. The stack pointer has to retain 16-byte alignment, longlongs
+// and doubles are aligned on 8-byte boundaries.
+
+#define PARAM_BUFFER_COUNT     16
+#define GPR_COUNT               8
+#define FPR_COUNT               8
+
+// PrepareAndDispatch() is called by SharedStub() and calls the actual method.
+//
+// - 'args[]' contains the arguments passed on stack
+// - 'gprData[]' contains the arguments passed in integer registers
+// - 'fprData[]' contains the arguments passed in floating point registers
+// 
+// The parameters are mapped into an array of type 'nsXPTCMiniVariant'
+// and then the method gets called.
+
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self,
+                   uint32_t methodIndex,
+                   uint32_t* args,
+                   uint32_t *gprData,
+                   double *fprData)
+{
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info = nullptr;
+    uint32_t paramCount;
+    uint32_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no method info");
+    if (! info)
+        return NS_ERROR_UNEXPECTED;
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+
+    NS_ASSERTION(dispatchParams,"no place for params");
+    if (!dispatchParams)
+        return NS_ERROR_OUT_OF_MEMORY;
+
+    uint32_t* ap = args;
+    uint32_t gpr = 1;    // skip one GPR register
+    uint32_t fpr = 0;
+    uint32_t tempu32;
+    uint64_t tempu64;
+
+    for(i = 0; i < paramCount; i++) {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+	
+        if (!param.IsOut() && type == nsXPTType::T_DOUBLE) {
+            if (fpr < FPR_COUNT)
+                dp->val.d = fprData[fpr++];
+            else {
+                if ((uint32_t) ap & 4) ap++; // doubles are 8-byte aligned on stack
+                dp->val.d = *(double*) ap;
+                ap += 2;
+            }
+            continue;
+        }
+        else if (!param.IsOut() && type == nsXPTType::T_FLOAT) {
+            if (fpr < FPR_COUNT)
+                dp->val.f = (float) fprData[fpr++]; // in registers floats are passed as doubles
+            else
+                dp->val.f = *(float*) ap++;
+            continue;
+        }
+        else if (!param.IsOut() && (type == nsXPTType::T_I64
+                                    || type == nsXPTType::T_U64)) {
+            if (gpr & 1) gpr++; // longlongs are aligned in odd/even register pairs, eg. r5/r6
+            if ((gpr + 1) < GPR_COUNT) {
+                tempu64 = *(uint64_t*) &gprData[gpr];
+                gpr += 2;
+            }
+            else {
+                if ((uint32_t) ap & 4) ap++; // longlongs are 8-byte aligned on stack
+                tempu64 = *(uint64_t*) ap;
+                ap += 2;
+            }
+        }
+        else {
+            if (gpr < GPR_COUNT)
+                tempu32 = gprData[gpr++];
+            else
+                tempu32 = *ap++;
+        }
+
+        if(param.IsOut() || !type.IsArithmetic()) {
+            if (type == nsXPTType::T_JSVAL)
+                dp->val.p = *((void**) tempu32);
+            else
+                dp->val.p = (void*) tempu32;
+            continue;
+        }
+
+        switch(type) {
+        case nsXPTType::T_I8:      dp->val.i8  = (int8_t)   tempu32; break;
+        case nsXPTType::T_I16:     dp->val.i16 = (int16_t)  tempu32; break;
+        case nsXPTType::T_I32:     dp->val.i32 = (int32_t)  tempu32; break;
+        case nsXPTType::T_I64:     dp->val.i64 = (int64_t)  tempu64; break;
+        case nsXPTType::T_U8:      dp->val.u8  = (uint8_t)  tempu32; break;
+        case nsXPTType::T_U16:     dp->val.u16 = (uint16_t) tempu32; break;
+        case nsXPTType::T_U32:     dp->val.u32 = (uint32_t) tempu32; break;
+        case nsXPTType::T_U64:     dp->val.u64 = (uint64_t) tempu64; break;
+        case nsXPTType::T_BOOL:    dp->val.b   = (bool)     tempu32; break;
+        case nsXPTType::T_CHAR:    dp->val.c   = (char)     tempu32; break;
+        case nsXPTType::T_WCHAR:   dp->val.wc  = (wchar_t)  tempu32; break;
+
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex,
+                                      info,
+                                      dispatchParams);
+
+    if (dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+// Load r11 with the constant 'n' and branch to SharedStub().
+//
+// XXX Yes, it's ugly that we're relying on gcc's name-mangling here;
+// however, it's quick, dirty, and'll break when the ABI changes on
+// us, which is what we want ;-).
+
+
+// gcc-3 version
+//
+// As G++3 ABI contains the length of the functionname in the mangled
+// name, it is difficult to get a generic assembler mechanism like
+// in the G++ 2.95 case.
+// Create names would be like:
+// _ZN14nsXPTCStubBase5Stub1Ev
+// _ZN14nsXPTCStubBase6Stub12Ev
+// _ZN14nsXPTCStubBase7Stub123Ev
+// _ZN14nsXPTCStubBase8Stub1234Ev
+// etc.
+// Use assembler directives to get the names right...
+
+# define STUB_ENTRY(n)							\
+__asm__ (								\
+	".align	2 \n\t"							\
+	".if	"#n" < 10 \n\t"						\
+	".globl	_ZN14nsXPTCStubBase5Stub"#n"Ev \n\t"			\
+	".type	_ZN14nsXPTCStubBase5Stub"#n"Ev,@function \n\n"		\
+"_ZN14nsXPTCStubBase5Stub"#n"Ev: \n\t"					\
+									\
+	".elseif "#n" < 100 \n\t"					\
+	".globl	_ZN14nsXPTCStubBase6Stub"#n"Ev \n\t"			\
+	".type	_ZN14nsXPTCStubBase6Stub"#n"Ev,@function \n\n"		\
+"_ZN14nsXPTCStubBase6Stub"#n"Ev: \n\t"					\
+									\
+	".elseif "#n" < 1000 \n\t"					\
+	".globl	_ZN14nsXPTCStubBase7Stub"#n"Ev \n\t"			\
+	".type	_ZN14nsXPTCStubBase7Stub"#n"Ev,@function \n\n"		\
+"_ZN14nsXPTCStubBase7Stub"#n"Ev: \n\t"					\
+									\
+	".else \n\t"							\
+	".err	\"stub number "#n" >= 1000 not yet supported\"\n"	\
+	".endif \n\t"							\
+									\
+	"li	11,"#n" \n\t"						\
+	"b	SharedStub@local \n"					\
+);
+
+#define SENTINEL_ENTRY(n)                            \
+nsresult nsXPTCStubBase::Sentinel##n()               \
+{                                                    \
+  NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+  return NS_ERROR_NOT_IMPLEMENTED;                   \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_rhapsody.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_rhapsody.cpp
new file mode 100644
index 000000000..4c485a275
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_rhapsody.cpp
@@ -0,0 +1,165 @@
+/* -*- Mode: C -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+/* Under the Mac OS X PowerPC ABI, the first 8 integer and 13 floating point
+ * parameters are delivered in registers and are not on the stack, although
+ * stack space is allocated for them.  The integer parameters are delivered
+ * in GPRs r3 through r10.  The first 8 words of the parameter area on the
+ * stack shadow these registers.  A word will either be in a register or on
+ * the stack, but not in both.  Although the first floating point parameters
+ * are passed in floating point registers, GPR space and stack space is
+ * reserved for them as well.
+ *
+ * SharedStub has passed pointers to the parameter section of the stack
+ * and saved copies of the GPRs and FPRs used for parameter passing.  We
+ * don't care about the first parameter (which is delivered here as the self
+ * pointer), so SharedStub pointed us past that.  argsGPR thus points to GPR
+ * r4 (corresponding to the first argument after the self pointer) and
+ * argsStack points to the parameter section of the caller's stack frame
+ * reserved for the same argument.  This way, it is possible to reference
+ * either argsGPR or argsStack with the same index.
+ *
+ * Contrary to the assumption made by the previous implementation, the
+ * Mac OS X PowerPC ABI doesn't impose any special alignment restrictions on
+ * parameter sections of stacks.  Values that are 64 bits wide appear on the
+ * stack without any special padding.
+ *
+ * See also xptcstubs_asm_ppc_darwin.s.m4:_SharedStub.
+ *
+ * ABI reference:
+ * http://developer.apple.com/documentation/DeveloperTools/Conceptual/
+ *  MachORuntime/PowerPCConventions/chapter_3_section_1.html */
+
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(
+  nsXPTCStubBase *self,
+  uint32_t        methodIndex,
+  uint32_t       *argsStack,
+  uint32_t       *argsGPR,
+  double         *argsFPR) {
+#define PARAM_BUFFER_COUNT 16
+#define PARAM_FPR_COUNT    13
+#define PARAM_GPR_COUNT     7
+
+  nsXPTCMiniVariant      paramBuffer[PARAM_BUFFER_COUNT];
+  nsXPTCMiniVariant     *dispatchParams = nullptr;
+  const nsXPTMethodInfo *methodInfo;
+  uint8_t                paramCount;
+  uint8_t                i;
+  nsresult               result         = NS_ERROR_FAILURE;
+  uint32_t               argIndex       = 0;
+  uint32_t               fprIndex       = 0;
+
+  typedef struct {
+    uint32_t hi;
+    uint32_t lo;
+  } DU;
+
+  NS_ASSERTION(self, "no self");
+
+  self->mEntry->GetMethodInfo(uint16_t(methodIndex), &methodInfo);
+  NS_ASSERTION(methodInfo, "no method info");
+
+  paramCount = methodInfo->GetParamCount();
+
+  if(paramCount > PARAM_BUFFER_COUNT) {
+    dispatchParams = new nsXPTCMiniVariant[paramCount];
+  }
+  else {
+    dispatchParams = paramBuffer;
+  }
+  NS_ASSERTION(dispatchParams,"no place for params");
+
+  for(i = 0; i < paramCount; i++, argIndex++) {
+    const nsXPTParamInfo &param = methodInfo->GetParam(i);
+    const nsXPTType      &type  = param.GetType();
+    nsXPTCMiniVariant    *dp    = &dispatchParams[i];
+    uint32_t              theParam;
+
+    if(argIndex < PARAM_GPR_COUNT)
+      theParam =   argsGPR[argIndex];
+    else
+      theParam = argsStack[argIndex];
+
+    if(param.IsOut() || !type.IsArithmetic())
+      dp->val.p = (void *) theParam;
+    else {
+      switch(type) {
+        case nsXPTType::T_I8:
+          dp->val.i8  =   (int8_t) theParam;
+          break;
+        case nsXPTType::T_I16:
+          dp->val.i16 =  (int16_t) theParam;
+          break;
+        case nsXPTType::T_I32:
+          dp->val.i32 =  (int32_t) theParam;
+          break;
+        case nsXPTType::T_U8:
+          dp->val.u8  =  (uint8_t) theParam;
+          break;
+        case nsXPTType::T_U16:
+          dp->val.u16 = (uint16_t) theParam;
+          break;
+        case nsXPTType::T_U32:
+          dp->val.u32 = (uint32_t) theParam;
+          break;
+        case nsXPTType::T_I64:
+        case nsXPTType::T_U64:
+          ((DU *)dp)->hi = (uint32_t) theParam;
+          if(++argIndex < PARAM_GPR_COUNT)
+            ((DU *)dp)->lo = (uint32_t)   argsGPR[argIndex];
+          else
+            ((DU *)dp)->lo = (uint32_t) argsStack[argIndex];
+          break;
+        case nsXPTType::T_BOOL:
+          dp->val.b   =   (bool) theParam;
+          break;
+        case nsXPTType::T_CHAR:
+          dp->val.c   =     (char) theParam;
+          break;
+        case nsXPTType::T_WCHAR:
+          dp->val.wc  =  (wchar_t) theParam;
+          break;
+        case nsXPTType::T_FLOAT:
+          if(fprIndex < PARAM_FPR_COUNT)
+            dp->val.f = (float) argsFPR[fprIndex++];
+          else
+            dp->val.f = *(float *) &argsStack[argIndex];
+          break;
+        case nsXPTType::T_DOUBLE:
+          if(fprIndex < PARAM_FPR_COUNT)
+            dp->val.d = argsFPR[fprIndex++];
+          else
+            dp->val.d = *(double *) &argsStack[argIndex];
+          argIndex++;
+          break;
+        default:
+          NS_ERROR("bad type");
+          break;
+      }
+    }
+  }
+
+  result = self->mOuter->
+    CallMethod((uint16_t)methodIndex, methodInfo, dispatchParams);
+
+  if(dispatchParams != paramBuffer)
+    delete [] dispatchParams;
+
+  return result;
+}
+
+#define STUB_ENTRY(n)
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_sparc64_openbsd.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_sparc64_openbsd.cpp
new file mode 100644
index 000000000..b8a09c97e
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_sparc64_openbsd.cpp
@@ -0,0 +1,104 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+#if defined(sparc) || defined(__sparc__)
+
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self, uint64_t methodIndex, uint64_t* args)
+{
+
+#define PARAM_BUFFER_COUNT     16
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no interface info");
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+
+    NS_ASSERTION(dispatchParams,"no place for params");
+    if (!dispatchParams)
+        return NS_ERROR_OUT_OF_MEMORY;
+
+    uint64_t* ap = args;
+    for(i = 0; i < paramCount; i++, ap++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            dp->val.p = (void*) *ap;
+            continue;
+        }
+        // else
+        switch(type)
+        {
+        case nsXPTType::T_BOOL   : dp->val.b   = *((int64_t*)  ap);      break;
+        case nsXPTType::T_CHAR   : dp->val.c   = *((uint64_t*) ap);      break;
+        case nsXPTType::T_WCHAR  : dp->val.wc  = *((int64_t*) ap);       break;
+        case nsXPTType::T_I8     : dp->val.i8  = *((int64_t*)  ap);      break;
+        case nsXPTType::T_I16    : dp->val.i16 = *((int64_t*) ap);       break;
+        case nsXPTType::T_I32    : dp->val.i32 = *((int64_t*) ap);       break;
+        case nsXPTType::T_I64    : dp->val.i64 = *((int64_t*) ap);       break;
+        case nsXPTType::T_U8     : dp->val.u8  = *((uint64_t*) ap);      break;
+        case nsXPTType::T_U16    : dp->val.u16 = *((uint64_t*)ap);       break;
+        case nsXPTType::T_U32    : dp->val.u32 = *((uint64_t*)ap);       break;
+        case nsXPTType::T_U64    : dp->val.u64 = *((uint64_t*) ap);      break;
+        case nsXPTType::T_FLOAT  : dp->val.f   = ((float*)   ap)[1];     break;
+        case nsXPTType::T_DOUBLE : dp->val.d   = *((double*) ap);        break;
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+extern "C" nsresult SharedStub(int, int*);
+
+#define STUB_ENTRY(n) \
+nsresult nsXPTCStubBase::Stub##n() \
+{ \
+	int dummy; /* defeat tail-call optimization */ \
+	return SharedStub(n, &dummy); \
+}
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
+
+#endif /* sparc || __sparc__ */
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_sparc_netbsd.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_sparc_netbsd.cpp
new file mode 100644
index 000000000..22bf94d49
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_sparc_netbsd.cpp
@@ -0,0 +1,117 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+
+#if defined(sparc) || defined(__sparc__)
+
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint32_t* args)
+{
+
+    typedef struct {
+        uint32_t hi;
+        uint32_t lo;
+    } DU;               // have to move 64 bit entities as 32 bit halves since
+                        // stack slots are not guaranteed 16 byte aligned
+
+#define PARAM_BUFFER_COUNT     16
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    nsIInterfaceInfo* iface_info = nullptr;
+    const nsXPTMethodInfo* info;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->GetInterfaceInfo(&iface_info);
+    NS_ASSERTION(iface_info,"no interface info");
+
+    iface_info->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no interface info");
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+    NS_ASSERTION(dispatchParams,"no place for params");
+
+    uint32_t* ap = args;
+    for(i = 0; i < paramCount; i++, ap++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            if (type == nsXPTType::T_JSVAL)
+                dp->val.p = *((void**) *ap);
+            else
+                dp->val.p = (void*) *ap;
+            continue;
+        }
+        // else
+        switch(type)
+        {
+        case nsXPTType::T_I8     : dp->val.i8  = *((int32_t*) ap);       break;
+        case nsXPTType::T_I16    : dp->val.i16 = *((int32_t*) ap);       break;
+        case nsXPTType::T_I32    : dp->val.i32 = *((int32_t*) ap);       break;
+        case nsXPTType::T_DOUBLE :
+        case nsXPTType::T_U64    :
+        case nsXPTType::T_I64    : ((DU *)dp)->hi = ((DU *)ap)->hi; 
+                                   ((DU *)dp)->lo = ((DU *)ap)->lo;
+                                   ap++;
+                                   break;
+        case nsXPTType::T_U8     : dp->val.u8  = *((uint32_t*)ap);       break;
+        case nsXPTType::T_U16    : dp->val.u16 = *((uint32_t*)ap);       break;
+        case nsXPTType::T_U32    : dp->val.u32 = *((uint32_t*)ap);       break;
+        case nsXPTType::T_FLOAT  : dp->val.f   = *((float*)   ap);       break;
+        case nsXPTType::T_BOOL   : dp->val.b   = *((uint32_t*)ap);       break;
+        case nsXPTType::T_CHAR   : dp->val.c   = *((uint32_t*)ap);       break;
+        case nsXPTType::T_WCHAR  : dp->val.wc  = *((int32_t*) ap);       break;
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    NS_RELEASE(iface_info);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+extern "C" nsresult SharedStub(int, int*);
+
+#define STUB_ENTRY(n) \
+nsresult nsXPTCStubBase::Stub##n() \
+{ \
+	int dummy; /* defeat tail-call optimization */ \
+	return SharedStub(n, &dummy); \
+}
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
+
+#endif /* sparc || __sparc__ */
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_sparc_openbsd.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_sparc_openbsd.cpp
new file mode 100644
index 000000000..55d814b85
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_sparc_openbsd.cpp
@@ -0,0 +1,120 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+
+#if defined(sparc) || defined(__sparc__)
+
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint32_t* args)
+{
+
+    typedef struct {
+        uint32_t hi;
+        uint32_t lo;
+    } DU;               // have to move 64 bit entities as 32 bit halves since
+                        // stack slots are not guaranteed 16 byte aligned
+
+#define PARAM_BUFFER_COUNT     16
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    nsIInterfaceInfo* iface_info = nullptr;
+    const nsXPTMethodInfo* info;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->GetInterfaceInfo(&iface_info);
+    NS_ASSERTION(iface_info,"no interface info");
+
+    iface_info->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no interface info");
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+
+    NS_ASSERTION(dispatchParams,"no place for params");
+    if (!dispatchParams)
+        return NS_ERROR_OUT_OF_MEMORY;
+
+    uint32_t* ap = args;
+    for(i = 0; i < paramCount; i++, ap++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            if (type == nsXPTType::T_JSVAL)
+                dp->val.p = *((void**) *ap);
+            else
+                dp->val.p = (void*) *ap;
+            continue;
+        }
+        // else
+        switch(type)
+        {
+        case nsXPTType::T_I8     : dp->val.i8  = *((int32_t*) ap);       break;
+        case nsXPTType::T_I16    : dp->val.i16 = *((int32_t*) ap);       break;
+        case nsXPTType::T_I32    : dp->val.i32 = *((int32_t*) ap);       break;
+        case nsXPTType::T_DOUBLE :
+        case nsXPTType::T_U64    :
+        case nsXPTType::T_I64    : ((DU *)dp)->hi = ((DU *)ap)->hi; 
+                                   ((DU *)dp)->lo = ((DU *)ap)->lo;
+                                   ap++;
+                                   break;
+        case nsXPTType::T_U8     : dp->val.u8  = *((uint32_t*)ap);       break;
+        case nsXPTType::T_U16    : dp->val.u16 = *((uint32_t*)ap);       break;
+        case nsXPTType::T_U32    : dp->val.u32 = *((uint32_t*)ap);       break;
+        case nsXPTType::T_FLOAT  : dp->val.f   = *((float*)   ap);       break;
+        case nsXPTType::T_BOOL   : dp->val.b   = *((uint32_t*)ap);       break;
+        case nsXPTType::T_CHAR   : dp->val.c   = *((uint32_t*)ap);       break;
+        case nsXPTType::T_WCHAR  : dp->val.wc  = *((int32_t*) ap);       break;
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    NS_RELEASE(iface_info);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+extern "C" nsresult SharedStub(int, int*);
+
+#define STUB_ENTRY(n) \
+nsresult nsXPTCStubBase::Stub##n() \
+{ \
+	int dummy; /* defeat tail-call optimization */ \
+	return SharedStub(n, &dummy); \
+}
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
+
+#endif /* sparc || __sparc__ */
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_sparc_solaris.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_sparc_solaris.cpp
new file mode 100644
index 000000000..61f3df4ff
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_sparc_solaris.cpp
@@ -0,0 +1,112 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+#if defined(sparc) || defined(__sparc__)
+
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint32_t* args)
+{
+
+    typedef struct {
+        uint32_t hi;
+        uint32_t lo;
+    } DU;               // have to move 64 bit entities as 32 bit halves since
+                        // stack slots are not guaranteed 16 byte aligned
+
+#define PARAM_BUFFER_COUNT     16
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no interface info");
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+    NS_ASSERTION(dispatchParams,"no place for params");
+
+    uint32_t* ap = args;
+    for(i = 0; i < paramCount; i++, ap++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            if (type == nsXPTType::T_JSVAL)
+                dp->val.p = *((void**) *ap);
+            else
+                dp->val.p = (void*) *ap;
+            continue;
+        }
+        // else
+        switch(type)
+        {
+        case nsXPTType::T_I8     : dp->val.i8  = *((int32_t*) ap);       break;
+        case nsXPTType::T_I16    : dp->val.i16 = *((int32_t*) ap);       break;
+        case nsXPTType::T_I32    : dp->val.i32 = *((int32_t*) ap);       break;
+        case nsXPTType::T_DOUBLE :
+        case nsXPTType::T_U64    :
+        case nsXPTType::T_I64    : ((DU *)dp)->hi = ((DU *)ap)->hi; 
+                                   ((DU *)dp)->lo = ((DU *)ap)->lo;
+                                   ap++;
+                                   break;
+        case nsXPTType::T_U8     : dp->val.u8  = *((uint32_t*)ap);       break;
+        case nsXPTType::T_U16    : dp->val.u16 = *((uint32_t*)ap);       break;
+        case nsXPTType::T_U32    : dp->val.u32 = *((uint32_t*)ap);       break;
+        case nsXPTType::T_FLOAT  : dp->val.f   = *((float*)   ap);       break;
+        case nsXPTType::T_BOOL   : dp->val.b   = *((uint32_t*)ap);       break;
+        case nsXPTType::T_CHAR   : dp->val.c   = *((uint32_t*)ap);       break;
+        case nsXPTType::T_WCHAR  : dp->val.wc  = *((int32_t*) ap);       break;
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+extern "C" nsresult SharedStub(int, int*);
+
+#define STUB_ENTRY(n) \
+nsresult nsXPTCStubBase::Stub##n() \
+{ \
+	int dummy; /* defeat tail-call optimization */ \
+	return SharedStub(n, &dummy); \
+}
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
+
+#endif /* sparc || __sparc__ */
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_sparcv9_solaris.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_sparcv9_solaris.cpp
new file mode 100644
index 000000000..583ce9864
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_sparcv9_solaris.cpp
@@ -0,0 +1,101 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+#if defined(sparc) || defined(__sparc__)
+
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self, uint64_t methodIndex, uint64_t* args)
+{
+
+#define PARAM_BUFFER_COUNT     16
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no interface info");
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+    NS_ASSERTION(dispatchParams,"no place for params");
+
+    uint64_t* ap = args;
+    for(i = 0; i < paramCount; i++, ap++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            dp->val.p = (void*) *ap;
+            continue;
+        }
+        // else
+        switch(type)
+        {
+        case nsXPTType::T_I8     : dp->val.i8  = *((int64_t*) ap);       break;
+        case nsXPTType::T_I16    : dp->val.i16 = *((int64_t*) ap);       break;
+        case nsXPTType::T_I32    : dp->val.i32 = *((int64_t*) ap);       break;
+        case nsXPTType::T_DOUBLE : dp->val.d   = *((double*)  ap);       break;
+        case nsXPTType::T_U64    : dp->val.u64 = *((uint64_t*)ap);       break;
+        case nsXPTType::T_I64    : dp->val.i64 = *((int64_t*) ap);       break;
+        case nsXPTType::T_U8     : dp->val.u8  = *((uint64_t*)ap);       break;
+        case nsXPTType::T_U16    : dp->val.u16 = *((uint64_t*)ap);       break;
+        case nsXPTType::T_U32    : dp->val.u32 = *((uint64_t*)ap);       break;
+        case nsXPTType::T_FLOAT  : dp->val.f   =  ((float*)   ap)[1];    break;
+        case nsXPTType::T_BOOL   : dp->val.b   = *((uint64_t*)ap);       break;
+        case nsXPTType::T_CHAR   : dp->val.c   = *((uint64_t*)ap);       break;
+        case nsXPTType::T_WCHAR  : dp->val.wc  = *((int64_t*) ap);       break;
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+extern "C" nsresult SharedStub(int, int*);
+
+#define STUB_ENTRY(n) \
+nsresult nsXPTCStubBase::Stub##n() \
+{ \
+	int dummy; /* defeat tail-call optimization */ \
+	return SharedStub(n, &dummy); \
+}
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
+
+#endif /* sparc || __sparc__ */
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_x86_64_darwin.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_x86_64_darwin.cpp
new file mode 100644
index 000000000..ae058567f
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_x86_64_darwin.cpp
@@ -0,0 +1,190 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Implement shared vtbl methods.
+
+// Keep this in sync with the linux version.
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+// The Darwin/x86-64 ABI passes the first 6 integer parameters and the
+// first 8 floating point parameters in registers (rdi, rsi, rdx, rcx,
+// r8, r9 and xmm0-xmm7), no stack space is allocated for these by the
+// caller.  The rest of the parameters are passed in the callers stack
+// area.
+
+const uint32_t PARAM_BUFFER_COUNT   = 16;
+const uint32_t GPR_COUNT            = 6;
+const uint32_t FPR_COUNT            = 8;
+
+// PrepareAndDispatch() is called by SharedStub() and calls the actual method.
+//
+// - 'args[]' contains the arguments passed on stack
+// - 'gpregs[]' contains the arguments passed in integer registers
+// - 'fpregs[]' contains the arguments passed in floating point registers
+// 
+// The parameters are mapped into an array of type 'nsXPTCMiniVariant'
+// and then the method gets called.
+
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase * self, uint32_t methodIndex,
+                   uint64_t * args, uint64_t * gpregs, double *fpregs)
+{
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info;
+    uint32_t paramCount;
+    uint32_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no method info");
+    if (!info)
+        return NS_ERROR_UNEXPECTED;
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if (paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+
+    NS_ASSERTION(dispatchParams,"no place for params");
+    if (!dispatchParams)
+        return NS_ERROR_OUT_OF_MEMORY;
+
+    uint64_t* ap = args;
+    uint32_t nr_gpr = 1;    // skip one GPR register for 'that'
+    uint32_t nr_fpr = 0;
+    uint64_t value;
+
+    for (i = 0; i < paramCount; i++) {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+	
+        if (!param.IsOut() && type == nsXPTType::T_DOUBLE) {
+            if (nr_fpr < FPR_COUNT)
+                dp->val.d = fpregs[nr_fpr++];
+            else
+                dp->val.d = *(double*) ap++;
+            continue;
+        }
+        else if (!param.IsOut() && type == nsXPTType::T_FLOAT) {
+            if (nr_fpr < FPR_COUNT)
+                // The value in %xmm register is already prepared to
+                // be retrieved as a float. Therefore, we pass the
+                // value verbatim, as a double without conversion.
+                dp->val.d = fpregs[nr_fpr++];
+            else
+                dp->val.f = *(float*) ap++;
+            continue;
+        }
+        else {
+            if (nr_gpr < GPR_COUNT)
+                value = gpregs[nr_gpr++];
+            else
+                value = *ap++;
+        }
+
+        if (param.IsOut() || !type.IsArithmetic()) {
+            dp->val.p = (void*) value;
+            continue;
+        }
+
+        switch (type) {
+        case nsXPTType::T_I8:      dp->val.i8  = (int8_t)   value; break;
+        case nsXPTType::T_I16:     dp->val.i16 = (int16_t)  value; break;
+        case nsXPTType::T_I32:     dp->val.i32 = (int32_t)  value; break;
+        case nsXPTType::T_I64:     dp->val.i64 = (int64_t)  value; break;
+        case nsXPTType::T_U8:      dp->val.u8  = (uint8_t)  value; break;
+        case nsXPTType::T_U16:     dp->val.u16 = (uint16_t) value; break;
+        case nsXPTType::T_U32:     dp->val.u32 = (uint32_t) value; break;
+        case nsXPTType::T_U64:     dp->val.u64 = (uint64_t) value; break;
+        // Cast to uint8_t first, to remove garbage on upper 56 bits.
+        case nsXPTType::T_BOOL:    dp->val.b   = (bool)(uint8_t)   value; break;
+        case nsXPTType::T_CHAR:    dp->val.c   = (char)     value; break;
+        case nsXPTType::T_WCHAR:   dp->val.wc  = (wchar_t)  value; break;
+
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t) methodIndex, info, dispatchParams);
+
+    if (dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+// Darwin/x86-64 uses gcc >= 4.2
+
+#define STUB_ENTRY(n) \
+asm(".section	__TEXT,__text\n\t" \
+    ".align	3\n\t" \
+    ".if	" #n " < 10\n\t" \
+    ".globl	__ZN14nsXPTCStubBase5Stub" #n "Ev\n\t" \
+    "__ZN14nsXPTCStubBase5Stub" #n "Ev:\n\t" \
+    ".elseif	" #n " < 100\n\t" \
+    ".globl	__ZN14nsXPTCStubBase6Stub" #n "Ev\n\t" \
+    "__ZN14nsXPTCStubBase6Stub" #n "Ev:\n\t" \
+    ".elseif    " #n " < 1000\n\t" \
+    ".globl     __ZN14nsXPTCStubBase7Stub" #n "Ev\n\t" \
+    "__ZN14nsXPTCStubBase7Stub" #n "Ev:\n\t" \
+    ".else\n\t" \
+    ".err	\"stub number " #n " >= 1000 not yet supported\"\n\t" \
+    ".endif\n\t" \
+    "movl	$" #n ", %eax\n\t" \
+    "jmp	SharedStub\n\t");
+
+// static nsresult SharedStub(uint32_t methodIndex)
+asm(".section   __TEXT,__text\n\t"
+    ".align     3\n\t"
+    "SharedStub:\n\t"
+    // make room for gpregs (48), fpregs (64)
+    "pushq      %rbp\n\t"
+    "movq       %rsp,%rbp\n\t"
+    "subq       $112,%rsp\n\t"
+    // save GP registers
+    "movq       %rdi,-112(%rbp)\n\t"
+    "movq       %rsi,-104(%rbp)\n\t"
+    "movq       %rdx, -96(%rbp)\n\t"
+    "movq       %rcx, -88(%rbp)\n\t"
+    "movq       %r8 , -80(%rbp)\n\t"
+    "movq       %r9 , -72(%rbp)\n\t"
+    "leaq       -112(%rbp),%rcx\n\t"
+    // save FP registers
+    "movsd      %xmm0,-64(%rbp)\n\t"
+    "movsd      %xmm1,-56(%rbp)\n\t"
+    "movsd      %xmm2,-48(%rbp)\n\t"
+    "movsd      %xmm3,-40(%rbp)\n\t"
+    "movsd      %xmm4,-32(%rbp)\n\t"
+    "movsd      %xmm5,-24(%rbp)\n\t"
+    "movsd      %xmm6,-16(%rbp)\n\t"
+    "movsd      %xmm7, -8(%rbp)\n\t"
+    "leaq       -64(%rbp),%r8\n\t"
+    // rdi has the 'self' pointer already
+    "movl       %eax,%esi\n\t"
+    "leaq       16(%rbp),%rdx\n\t"
+    "call       _PrepareAndDispatch\n\t"
+    "leave\n\t"
+    "ret\n\t");
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_x86_64_linux.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_x86_64_linux.cpp
new file mode 100644
index 000000000..01044363b
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_x86_64_linux.cpp
@@ -0,0 +1,204 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Implement shared vtbl methods.
+
+// Keep this in sync with the darwin version.
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+// The Linux/x86-64 ABI passes the first 6 integer parameters and the
+// first 8 floating point parameters in registers (rdi, rsi, rdx, rcx,
+// r8, r9 and xmm0-xmm7), no stack space is allocated for these by the
+// caller.  The rest of the parameters are passed in the callers stack
+// area.
+
+const uint32_t PARAM_BUFFER_COUNT   = 16;
+const uint32_t GPR_COUNT            = 6;
+const uint32_t FPR_COUNT            = 8;
+
+// PrepareAndDispatch() is called by SharedStub() and calls the actual method.
+//
+// - 'args[]' contains the arguments passed on stack
+// - 'gpregs[]' contains the arguments passed in integer registers
+// - 'fpregs[]' contains the arguments passed in floating point registers
+// 
+// The parameters are mapped into an array of type 'nsXPTCMiniVariant'
+// and then the method gets called.
+
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase * self, uint32_t methodIndex,
+                   uint64_t * args, uint64_t * gpregs, double *fpregs)
+{
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info;
+    uint32_t paramCount;
+    uint32_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no method info");
+    if (!info)
+        return NS_ERROR_UNEXPECTED;
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if (paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+
+    NS_ASSERTION(dispatchParams,"no place for params");
+    if (!dispatchParams)
+        return NS_ERROR_OUT_OF_MEMORY;
+
+    uint64_t* ap = args;
+    uint32_t nr_gpr = 1;    // skip one GPR register for 'that'
+    uint32_t nr_fpr = 0;
+    uint64_t value;
+
+    for (i = 0; i < paramCount; i++) {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+	
+        if (!param.IsOut() && type == nsXPTType::T_DOUBLE) {
+            if (nr_fpr < FPR_COUNT)
+                dp->val.d = fpregs[nr_fpr++];
+            else
+                dp->val.d = *(double*) ap++;
+            continue;
+        }
+        else if (!param.IsOut() && type == nsXPTType::T_FLOAT) {
+            if (nr_fpr < FPR_COUNT)
+                // The value in %xmm register is already prepared to
+                // be retrieved as a float. Therefore, we pass the
+                // value verbatim, as a double without conversion.
+                dp->val.d = fpregs[nr_fpr++];
+            else
+                dp->val.f = *(float*) ap++;
+            continue;
+        }
+        else {
+            if (nr_gpr < GPR_COUNT)
+                value = gpregs[nr_gpr++];
+            else
+                value = *ap++;
+        }
+
+        if (param.IsOut() || !type.IsArithmetic()) {
+            dp->val.p = (void*) value;
+            continue;
+        }
+
+        switch (type) {
+        case nsXPTType::T_I8:      dp->val.i8  = (int8_t)   value; break;
+        case nsXPTType::T_I16:     dp->val.i16 = (int16_t)  value; break;
+        case nsXPTType::T_I32:     dp->val.i32 = (int32_t)  value; break;
+        case nsXPTType::T_I64:     dp->val.i64 = (int64_t)  value; break;
+        case nsXPTType::T_U8:      dp->val.u8  = (uint8_t)  value; break;
+        case nsXPTType::T_U16:     dp->val.u16 = (uint16_t) value; break;
+        case nsXPTType::T_U32:     dp->val.u32 = (uint32_t) value; break;
+        case nsXPTType::T_U64:     dp->val.u64 = (uint64_t) value; break;
+        // Cast to uint8_t first, to remove garbage on upper 56 bits.
+        case nsXPTType::T_BOOL:    dp->val.b   = (bool)(uint8_t)   value; break;
+        case nsXPTType::T_CHAR:    dp->val.c   = (char)     value; break;
+        case nsXPTType::T_WCHAR:   dp->val.wc  = (wchar_t)  value; break;
+
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t) methodIndex, info, dispatchParams);
+
+    if (dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+// Linux/x86-64 uses gcc >= 3.1
+#define STUB_ENTRY(n) \
+asm(".section	\".text\"\n\t" \
+    ".align	2\n\t" \
+    ".if	" #n " < 10\n\t" \
+    ".globl	_ZN14nsXPTCStubBase5Stub" #n "Ev\n\t" \
+    ".hidden	_ZN14nsXPTCStubBase5Stub" #n "Ev\n\t" \
+    ".type	_ZN14nsXPTCStubBase5Stub" #n "Ev,@function\n" \
+    "_ZN14nsXPTCStubBase5Stub" #n "Ev:\n\t" \
+    ".elseif	" #n " < 100\n\t" \
+    ".globl	_ZN14nsXPTCStubBase6Stub" #n "Ev\n\t" \
+    ".hidden	_ZN14nsXPTCStubBase6Stub" #n "Ev\n\t" \
+    ".type	_ZN14nsXPTCStubBase6Stub" #n "Ev,@function\n" \
+    "_ZN14nsXPTCStubBase6Stub" #n "Ev:\n\t" \
+    ".elseif    " #n " < 1000\n\t" \
+    ".globl     _ZN14nsXPTCStubBase7Stub" #n "Ev\n\t" \
+    ".hidden    _ZN14nsXPTCStubBase7Stub" #n "Ev\n\t" \
+    ".type      _ZN14nsXPTCStubBase7Stub" #n "Ev,@function\n" \
+    "_ZN14nsXPTCStubBase7Stub" #n "Ev:\n\t" \
+    ".else\n\t" \
+    ".err	\"stub number " #n " >= 1000 not yet supported\"\n\t" \
+    ".endif\n\t" \
+    "movl	$" #n ", %eax\n\t" \
+    "jmp	SharedStub\n\t" \
+    ".if	" #n " < 10\n\t" \
+    ".size	_ZN14nsXPTCStubBase5Stub" #n "Ev,.-_ZN14nsXPTCStubBase5Stub" #n "Ev\n\t" \
+    ".elseif	" #n " < 100\n\t" \
+    ".size	_ZN14nsXPTCStubBase6Stub" #n "Ev,.-_ZN14nsXPTCStubBase6Stub" #n "Ev\n\t" \
+    ".else\n\t" \
+    ".size	_ZN14nsXPTCStubBase7Stub" #n "Ev,.-_ZN14nsXPTCStubBase7Stub" #n "Ev\n\t" \
+    ".endif");
+
+// static nsresult SharedStub(uint32_t methodIndex)
+asm(".section   \".text\"\n\t"
+    ".align     2\n\t"
+    ".type      SharedStub,@function\n\t"
+    "SharedStub:\n\t"
+    // make room for gpregs (48), fpregs (64)
+    "pushq      %rbp\n\t"
+    "movq       %rsp,%rbp\n\t"
+    "subq       $112,%rsp\n\t"
+    // save GP registers
+    "movq       %rdi,-112(%rbp)\n\t"
+    "movq       %rsi,-104(%rbp)\n\t"
+    "movq       %rdx, -96(%rbp)\n\t"
+    "movq       %rcx, -88(%rbp)\n\t"
+    "movq       %r8 , -80(%rbp)\n\t"
+    "movq       %r9 , -72(%rbp)\n\t"
+    "leaq       -112(%rbp),%rcx\n\t"
+    // save FP registers
+    "movsd      %xmm0,-64(%rbp)\n\t"
+    "movsd      %xmm1,-56(%rbp)\n\t"
+    "movsd      %xmm2,-48(%rbp)\n\t"
+    "movsd      %xmm3,-40(%rbp)\n\t"
+    "movsd      %xmm4,-32(%rbp)\n\t"
+    "movsd      %xmm5,-24(%rbp)\n\t"
+    "movsd      %xmm6,-16(%rbp)\n\t"
+    "movsd      %xmm7, -8(%rbp)\n\t"
+    "leaq       -64(%rbp),%r8\n\t"
+    // rdi has the 'self' pointer already
+    "movl       %eax,%esi\n\t"
+    "leaq       16(%rbp),%rdx\n\t"
+    "call       PrepareAndDispatch@plt\n\t"
+    "leave\n\t"
+    "ret\n\t"
+    ".size      SharedStub,.-SharedStub");
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_x86_64_solaris.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_x86_64_solaris.cpp
new file mode 100644
index 000000000..677fa9960
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_x86_64_solaris.cpp
@@ -0,0 +1,139 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Implement shared vtbl methods.
+
+// Keep this in sync with the darwin version.
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+// The Linux/x86-64 ABI passes the first 6 integer parameters and the
+// first 8 floating point parameters in registers (rdi, rsi, rdx, rcx,
+// r8, r9 and xmm0-xmm7), no stack space is allocated for these by the
+// caller.  The rest of the parameters are passed in the callers stack
+// area.
+
+const uint32_t PARAM_BUFFER_COUNT   = 16;
+const uint32_t GPR_COUNT            = 6;
+const uint32_t FPR_COUNT            = 8;
+
+// PrepareAndDispatch() is called by SharedStub() and calls the actual method.
+//
+// - 'args[]' contains the arguments passed on stack
+// - 'gpregs[]' contains the arguments passed in integer registers
+// - 'fpregs[]' contains the arguments passed in floating point registers
+// 
+// The parameters are mapped into an array of type 'nsXPTCMiniVariant'
+// and then the method gets called.
+
+extern "C" nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase * self, uint32_t methodIndex,
+                   uint64_t * args, uint64_t * gpregs, double *fpregs)
+{
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info;
+    uint32_t paramCount;
+    uint32_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no method info");
+    if (!info)
+        return NS_ERROR_UNEXPECTED;
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if (paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+
+    NS_ASSERTION(dispatchParams,"no place for params");
+    if (!dispatchParams)
+        return NS_ERROR_OUT_OF_MEMORY;
+
+    uint64_t* ap = args;
+    uint32_t nr_gpr = 1;    // skip one GPR register for 'that'
+    uint32_t nr_fpr = 0;
+    uint64_t value;
+
+    for (i = 0; i < paramCount; i++) {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+	
+        if (!param.IsOut() && type == nsXPTType::T_DOUBLE) {
+            if (nr_fpr < FPR_COUNT)
+                dp->val.d = fpregs[nr_fpr++];
+            else
+                dp->val.d = *(double*) ap++;
+            continue;
+        }
+        else if (!param.IsOut() && type == nsXPTType::T_FLOAT) {
+            if (nr_fpr < FPR_COUNT)
+                // The value in %xmm register is already prepared to
+                // be retrieved as a float. Therefore, we pass the
+                // value verbatim, as a double without conversion.
+                dp->val.d = fpregs[nr_fpr++];
+            else
+                dp->val.f = *(float*) ap++;
+            continue;
+        }
+        else {
+            if (nr_gpr < GPR_COUNT)
+                value = gpregs[nr_gpr++];
+            else
+                value = *ap++;
+        }
+
+        if (param.IsOut() || !type.IsArithmetic()) {
+            dp->val.p = (void*) value;
+            continue;
+        }
+
+        switch (type) {
+        case nsXPTType::T_I8:      dp->val.i8  = (int8_t)   value; break;
+        case nsXPTType::T_I16:     dp->val.i16 = (int16_t)  value; break;
+        case nsXPTType::T_I32:     dp->val.i32 = (int32_t)  value; break;
+        case nsXPTType::T_I64:     dp->val.i64 = (int64_t)  value; break;
+        case nsXPTType::T_U8:      dp->val.u8  = (uint8_t)  value; break;
+        case nsXPTType::T_U16:     dp->val.u16 = (uint16_t) value; break;
+        case nsXPTType::T_U32:     dp->val.u32 = (uint32_t) value; break;
+        case nsXPTType::T_U64:     dp->val.u64 = (uint64_t) value; break;
+        // Cast to uint8_t first, to remove garbage on upper 56 bits.
+        case nsXPTType::T_BOOL:    dp->val.b   = (bool)(uint8_t)   value; break;
+        case nsXPTType::T_CHAR:    dp->val.c   = (char)     value; break;
+        case nsXPTType::T_WCHAR:   dp->val.wc  = (wchar_t)  value; break;
+
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t) methodIndex, info, dispatchParams);
+
+    if (dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+#define STUB_ENTRY(n)
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_x86_solaris.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_x86_solaris.cpp
new file mode 100644
index 000000000..39eec5e54
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_x86_solaris.cpp
@@ -0,0 +1,77 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+nsresult ATTRIBUTE_USED
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint32_t* args)
+{
+#define PARAM_BUFFER_COUNT     16
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no interface info");
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+    NS_ASSERTION(dispatchParams,"no place for params");
+
+    uint32_t* ap = args;
+    for(i = 0; i < paramCount; i++, ap++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            dp->val.p = (void*) *ap;
+            continue;
+        }
+        // else
+	    dp->val.p = (void*) *ap;
+        switch(type)
+        {
+        case nsXPTType::T_I64    : dp->val.i64 = *((int64_t*) ap); ap++; break;
+        case nsXPTType::T_U64    : dp->val.u64 = *((uint64_t*)ap); ap++; break;
+        case nsXPTType::T_DOUBLE : dp->val.d   = *((double*)  ap); ap++; break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+#define STUB_ENTRY(n)
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
diff --git a/xpcom/reflect/xptcall/md/win32/moz.build b/xpcom/reflect/xptcall/md/win32/moz.build
new file mode 100644
index 000000000..5dbe41d76
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/win32/moz.build
@@ -0,0 +1,45 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+if CONFIG['TARGET_CPU'] == 'x86_64':
+    if CONFIG['GNU_CXX']:
+        SOURCES += [
+            'xptcinvoke_x86_64.cpp',
+            'xptcstubs_x86_64_gnu.cpp',
+        ]
+        SOURCES += [
+            'xptcinvoke_asm_x86_64_gnu.s'
+        ]
+    else:
+        SOURCES += [
+            'xptcinvoke_x86_64.cpp',
+            'xptcstubs_x86_64.cpp'
+        ]
+        SOURCES += [
+            'xptcinvoke_asm_x86_64.asm',
+            'xptcstubs_asm_x86_64.asm'
+        ]
+else:
+    if CONFIG['GNU_CXX']:
+        SOURCES += [
+            'xptcinvoke_x86_gnu.cpp',
+            'xptcstubs.cpp',
+        ]
+    else:
+        SOURCES += [
+            'xptcinvoke.cpp',
+            'xptcinvoke_asm_x86_msvc.asm',
+            'xptcstubs.cpp',
+        ]
+        SOURCES['xptcinvoke.cpp'].no_pgo = True
+        SOURCES['xptcinvoke_asm_x86_msvc.asm'].flags += ['-safeseh']
+
+FINAL_LIBRARY = 'xul'
+
+LOCAL_INCLUDES += [
+    '../..',
+    '/xpcom/reflect/xptinfo',
+]
diff --git a/xpcom/reflect/xptcall/md/win32/xptcinvoke.cpp b/xpcom/reflect/xptcall/md/win32/xptcinvoke.cpp
new file mode 100644
index 000000000..faec869f6
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/win32/xptcinvoke.cpp
@@ -0,0 +1,45 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+#ifndef WIN32
+#error "This code is for Win32 only"
+#endif
+
+extern "C" void __fastcall
+invoke_copy_to_stack(uint32_t* d, uint32_t paramCount, nsXPTCVariant* s)
+{
+    for(; paramCount > 0; paramCount--, d++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            *((void**)d) = s->ptr;
+            continue;
+        }
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     : *((int8_t*)  d) = s->val.i8;          break;
+        case nsXPTType::T_I16    : *((int16_t*) d) = s->val.i16;         break;
+        case nsXPTType::T_I32    : *((int32_t*) d) = s->val.i32;         break;
+        case nsXPTType::T_I64    : *((int64_t*) d) = s->val.i64; d++;    break;
+        case nsXPTType::T_U8     : *((uint8_t*) d) = s->val.u8;          break;
+        case nsXPTType::T_U16    : *((uint16_t*)d) = s->val.u16;         break;
+        case nsXPTType::T_U32    : *((uint32_t*)d) = s->val.u32;         break;
+        case nsXPTType::T_U64    : *((uint64_t*)d) = s->val.u64; d++;    break;
+        case nsXPTType::T_FLOAT  : *((float*)   d) = s->val.f;           break;
+        case nsXPTType::T_DOUBLE : *((double*)  d) = s->val.d;   d++;    break;
+        case nsXPTType::T_BOOL   : *((bool*)  d) = s->val.b;           break;
+        case nsXPTType::T_CHAR   : *((char*)    d) = s->val.c;           break;
+        case nsXPTType::T_WCHAR  : *((wchar_t*) d) = s->val.wc;          break;
+        default:
+            // all the others are plain pointer types
+            *((void**)d) = s->val.p;
+            break;
+        }
+    }
+}
diff --git a/xpcom/reflect/xptcall/md/win32/xptcinvoke_asm_x86_64.asm b/xpcom/reflect/xptcall/md/win32/xptcinvoke_asm_x86_64.asm
new file mode 100644
index 000000000..bf7c2ef0c
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/win32/xptcinvoke_asm_x86_64.asm
@@ -0,0 +1,107 @@
+; This Source Code Form is subject to the terms of the Mozilla Public
+; License, v. 2.0. If a copy of the MPL was not distributed with this
+; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+extrn invoke_copy_to_stack:PROC
+
+
+.CODE
+
+;
+;XPTC__InvokebyIndex(nsISupports* that, uint32_t methodIndex,
+;                   uint32_t paramCount, nsXPTCVariant* params)
+;
+
+XPTC__InvokebyIndex PROC FRAME
+
+   ; store register parameters
+
+    mov     qword ptr [rsp+32], r9        ; params
+    mov     dword ptr [rsp+24], r8d       ; paramCount
+    mov     dword ptr [rsp+16], edx       ; methodIndex
+    mov     qword ptr [rsp+8], rcx        ; that
+
+    push    rbp
+    .PUSHREG rbp
+    mov     rbp, rsp            ; store current RSP to RBP
+    .SETFRAME rbp, 0
+    .ENDPROLOG
+
+    sub     rsp, 32
+
+    ; maybe we don't have any parameters to copy
+
+    test    r8d, r8d
+    jz      noparams
+
+    ;
+    ; Build stack for stdcall
+    ;
+
+    ; 1st parameter is space for parameters
+
+    mov     eax, r8d
+    or      eax, 1
+    shl     rax, 3              ; *= 8
+    sub     rsp, rax
+    mov     rcx, rsp
+
+    ; 2nd parameter is parameter count
+
+    mov     edx, r8d
+
+    ; 3rd parameter is params
+
+    mov     r8, r9
+
+    sub     rsp, 40
+    call    invoke_copy_to_stack ; rcx = d
+                                 ; edx = paramCount
+                                 ; r8  = s
+    add     rsp, 32
+
+    ; Current stack is the following.
+    ;
+    ;  0h: [space (for this)]
+    ;  8h: [1st parameter]
+    ; 10h: [2nd parameter]
+    ; 18h: [3rd parameter]
+    ; 20h: [4th parameter]
+    ; ...
+    ;
+    ; On Win64 ABI, the first 4 parameters are passed using registers,
+    ; and others are on stack. 
+
+    ; 1st, 2nd and 3rd arguments are passed via registers
+
+    mov     rdx, qword ptr [rsp+8] ; 1st parameter
+    movsd   xmm1, qword ptr [rsp+8] ; for double
+
+    mov     r8, qword ptr [rsp+16] ; 2nd parameter
+    movsd   xmm2, qword ptr [rsp+16] ; for double
+
+    mov     r9, qword ptr [rsp+24] ; 3rd parameter
+    movsd   xmm3, qword ptr [rsp+24] ; for double
+
+    ; rcx register is this
+
+    mov     rcx, qword ptr [rbp+8+8] ; that
+
+noparams:
+
+    ; calculate call address
+
+    mov     r11, qword ptr [rcx]
+    mov     eax, dword ptr [rbp+16+8] ; methodIndex
+
+    call    qword ptr [r11+rax*8]      ; stdcall, i.e. callee cleans up stack.
+
+    mov     rsp, rbp
+    pop     rbp
+
+    ret
+
+XPTC__InvokebyIndex ENDP
+
+
+END
diff --git a/xpcom/reflect/xptcall/md/win32/xptcinvoke_asm_x86_64_gnu.s b/xpcom/reflect/xptcall/md/win32/xptcinvoke_asm_x86_64_gnu.s
new file mode 100644
index 000000000..006e0444b
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/win32/xptcinvoke_asm_x86_64_gnu.s
@@ -0,0 +1,110 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+.extern invoke_copy_to_stack
+
+
+.text
+.intel_syntax noprefix
+
+#
+#_XPTC__InvokebyIndex(nsISupports* that, uint32_t methodIndex,
+#                    uint32_t paramCount, nsXPTCVariant* params)
+#
+
+.globl XPTC__InvokebyIndex
+.def XPTC__InvokebyIndex
+   .scl 3
+   .type 46
+.endef
+XPTC__InvokebyIndex:
+
+   # store register parameters
+
+    mov     qword ptr [rsp+32], r9        # params
+    mov     dword ptr [rsp+24], r8d       # paramCount
+    mov     dword ptr [rsp+16], edx       # methodIndex
+    mov     qword ptr [rsp+8], rcx        # that
+
+    push    rbp
+    # .PUSHREG rbp
+    mov     rbp, rsp            # store current RSP to RBP
+    # .SETFRAME rbp, 0
+    # .ENDPROLOG
+
+    sub     rsp, 32
+
+    # maybe we don't have any parameters to copy
+
+    test    r8d, r8d
+    jz      noparams
+
+    #
+    # Build stack for stdcall
+    #
+
+    # 1st parameter is space for parameters
+
+    mov     eax, r8d
+    or      eax, 1
+    shl     rax, 3              # *= 8
+    sub     rsp, rax
+    mov     rcx, rsp
+
+    # 2nd parameter is parameter count
+
+    mov     edx, r8d
+
+    # 3rd parameter is params
+
+    mov     r8, r9
+
+    sub     rsp, 40
+    call    invoke_copy_to_stack # rcx = d
+                                 # edx = paramCount
+                                 # r8  = s
+    add     rsp, 32
+
+    # Current stack is the following.
+    #
+    #  0h: [space (for this)]
+    #  8h: [1st parameter]
+    # 10h: [2nd parameter]
+    # 18h: [3rd parameter]
+    # 20h: [4th parameter]
+    # ...
+    #
+    # On Win64 ABI, the first 4 parameters are passed using registers,
+    # and others are on stack. 
+
+    # 1st, 2nd and 3rd arguments are passed via registers
+
+    mov     rdx, qword ptr [rsp+8] # 1st parameter
+    movsd   xmm1, qword ptr [rsp+8] # for double
+
+    mov     r8, qword ptr [rsp+16] # 2nd parameter
+    movsd   xmm2, qword ptr [rsp+16] # for double
+
+    mov     r9, qword ptr [rsp+24] # 3rd parameter
+    movsd   xmm3, qword ptr [rsp+24] # for double
+
+    # rcx register is this
+
+    mov     rcx, qword ptr [rbp+8+8] # that
+
+noparams:
+
+    # calculate call address
+
+    mov     r11, qword ptr [rcx]
+    mov     eax, dword ptr [rbp+16+8] # methodIndex
+
+    call    qword ptr [r11+rax*8]      # stdcall, i.e. callee cleans up stack.
+
+    mov     rsp, rbp
+    pop     rbp
+
+    ret
+
+
diff --git a/xpcom/reflect/xptcall/md/win32/xptcinvoke_asm_x86_msvc.asm b/xpcom/reflect/xptcall/md/win32/xptcinvoke_asm_x86_msvc.asm
new file mode 100644
index 000000000..f3b7a1826
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/win32/xptcinvoke_asm_x86_msvc.asm
@@ -0,0 +1,63 @@
+; This Source Code Form is subject to the terms of the Mozilla Public
+; License, v. 2.0. If a copy of the MPL was not distributed with this
+; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+	TITLE xptcinvoke_asm_x86_msvc.asm
+	.686P
+	.model flat
+
+PUBLIC _NS_InvokeByIndex
+EXTRN @invoke_copy_to_stack@12:PROC
+
+;
+; extern "C" nsresult __cdecl
+; NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+;                  uint32_t paramCount, nsXPTCVariant* params)
+;
+
+_TEXT	SEGMENT
+_NS_InvokeByIndex PROC
+
+    ; Build frame
+    push ebp
+    mov	ebp, esp
+
+    ; Save paramCount for later
+    mov edx, dword ptr [ebp+16]
+
+    ; Do we have any parameters?
+    test edx, edx
+    jz noparams
+
+    ; Build call for copy_to_stack, which is __fastcall
+
+    ; Allocate space for parameters.  8 is the biggest size
+    ; any parameter can be, so assume that all our parameters
+    ; are that large.
+    mov eax, edx
+    shl eax, 3
+    sub esp, eax
+
+    mov ecx, esp
+    push dword ptr [ebp+20]
+    call @invoke_copy_to_stack@12
+noparams:
+    ; Push the `this' parameter for the call.
+    mov ecx, dword ptr [ebp+8]
+    push ecx
+
+    ; Load the vtable.
+    mov edx, dword ptr [ecx]
+
+    ; Call the vtable index at `methodIndex'.
+    mov eax, dword ptr [ebp+12]
+    call dword ptr [edx+eax*4]
+
+    ; Reset and return.
+    mov esp, ebp
+    pop ebp
+    ret
+_NS_InvokeByIndex ENDP
+_TEXT	ENDS
+
+END
diff --git a/xpcom/reflect/xptcall/md/win32/xptcinvoke_x86_64.cpp b/xpcom/reflect/xptcall/md/win32/xptcinvoke_x86_64.cpp
new file mode 100644
index 000000000..36b454b35
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/win32/xptcinvoke_x86_64.cpp
@@ -0,0 +1,59 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+extern "C" void
+invoke_copy_to_stack(uint64_t* d, uint32_t paramCount, nsXPTCVariant* s)
+{
+   for(; paramCount > 0; paramCount--, d++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            *((void**)d) = s->ptr;
+            continue;
+        }
+
+        /*
+         * AMD64 platform uses 8 bytes align.
+         */
+
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     : *((int8_t*)  d) = s->val.i8;          break;
+        case nsXPTType::T_I16    : *((int16_t*) d) = s->val.i16;         break;
+        case nsXPTType::T_I32    : *((int32_t*) d) = s->val.i32;         break;
+        case nsXPTType::T_I64    : *((int64_t*) d) = s->val.i64;         break;
+        case nsXPTType::T_U8     : *((uint8_t*) d) = s->val.u8;          break;
+        case nsXPTType::T_U16    : *((uint16_t*)d) = s->val.u16;         break;
+        case nsXPTType::T_U32    : *((uint32_t*)d) = s->val.u32;         break;
+        case nsXPTType::T_U64    : *((uint64_t*)d) = s->val.u64;         break;
+        case nsXPTType::T_FLOAT  : *((float*)   d) = s->val.f;           break;
+        case nsXPTType::T_DOUBLE : *((double*)  d) = s->val.d;           break;
+        case nsXPTType::T_BOOL   : *((bool*)  d) = s->val.b;           break;
+        case nsXPTType::T_CHAR   : *((char*)    d) = s->val.c;           break;
+        case nsXPTType::T_WCHAR  : *((wchar_t*) d) = s->val.wc;          break;
+        default:
+            // all the others are plain pointer types
+            *((void**)d) = s->val.p;
+            break;
+        }
+    }
+}
+
+extern "C" nsresult
+XPTC__InvokebyIndex(nsISupports* that, uint32_t methodIndex,
+                    uint32_t paramCount, nsXPTCVariant* params);
+
+extern "C"
+EXPORT_XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                   uint32_t paramCount, nsXPTCVariant* params)
+{
+    return XPTC__InvokebyIndex(that, methodIndex, paramCount, params);
+}
+
diff --git a/xpcom/reflect/xptcall/md/win32/xptcinvoke_x86_gnu.cpp b/xpcom/reflect/xptcall/md/win32/xptcinvoke_x86_gnu.cpp
new file mode 100644
index 000000000..0e73e99f3
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/win32/xptcinvoke_x86_gnu.cpp
@@ -0,0 +1,106 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+extern "C" {
+void __attribute__ ((__used__)) __attribute__ ((regparm(3)))
+invoke_copy_to_stack(uint32_t paramCount, nsXPTCVariant* s, uint32_t* d)
+{
+    for(uint32_t i = paramCount; i >0; i--, d++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            *((void**)d) = s->ptr;
+            continue;
+        }
+
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     : *((int8_t*)  d) = s->val.i8;          break;
+        case nsXPTType::T_I16    : *((int16_t*) d) = s->val.i16;         break;
+        case nsXPTType::T_I32    : *((int32_t*) d) = s->val.i32;         break;
+        case nsXPTType::T_I64    : *((int64_t*) d) = s->val.i64; d++;    break;
+        case nsXPTType::T_U8     : *((uint8_t*) d) = s->val.u8;          break;
+        case nsXPTType::T_U16    : *((uint16_t*)d) = s->val.u16;         break;
+        case nsXPTType::T_U32    : *((uint32_t*)d) = s->val.u32;         break;
+        case nsXPTType::T_U64    : *((uint64_t*)d) = s->val.u64; d++;    break;
+        case nsXPTType::T_FLOAT  : *((float*)   d) = s->val.f;           break;
+        case nsXPTType::T_DOUBLE : *((double*)  d) = s->val.d;   d++;    break;
+        case nsXPTType::T_BOOL   : *((bool*)    d) = s->val.b;           break;
+        case nsXPTType::T_CHAR   : *((char*)    d) = s->val.c;           break;
+        case nsXPTType::T_WCHAR  : *((wchar_t*) d) = s->val.wc;          break;
+        default:
+            // all the others are plain pointer types
+            *((void**)d) = s->val.p;
+            break;
+        }
+    }
+}
+} // extern "C"
+
+/*
+  EXPORT_XPCOM_API(nsresult)
+  NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                   uint32_t paramCount, nsXPTCVariant* params);
+
+  Each param takes at most two 4-byte words.
+  It doesn't matter if we push too many words, and calculating the exact
+  amount takes time.
+
+  that        = ebp + 0x08
+  methodIndex = ebp + 0x0c
+  paramCount  = ebp + 0x10
+  params      = ebp + 0x14
+
+*/
+
+__asm__ (
+	".text\n\t"
+/* alignment here seems unimportant here; this was 16, now it's 2 which
+   is what xptcstubs uses. */
+	".align 2\n\t"
+	".globl _NS_InvokeByIndex\n\t"
+	"_NS_InvokeByIndex:\n\t"
+	"pushl %ebp\n\t"
+	"movl  %esp, %ebp\n\t"
+	"movl  0x10(%ebp), %eax\n\t"
+	"leal  0(,%eax,8),%edx\n\t"
+
+        /* set up call frame for method. */
+	"subl  %edx, %esp\n\t"       /* make room for params. */
+/* Align to maximum x86 data size: 128 bits == 16 bytes == XMM register size.
+ * This is to avoid protection faults where SSE+ alignment of stack pointer
+ * is assumed and required, e.g. by GCC4's -ftree-vectorize option.
+ */
+	"andl  $0xfffffff0, %esp\n\t"   /* drop(?) stack ptr to 128-bit align */
+/* $esp should be aligned to a 16-byte boundary here (note we include an 
+ * additional 4 bytes in a later push instruction). This will ensure $ebp 
+ * in the function called below is aligned to a 0x8 boundary. SSE instructions 
+ * like movapd/movdqa expect memory operand to be aligned on a 16-byte
+ * boundary. The GCC compiler will generate the memory operand using $ebp
+ * with an 8-byte offset.
+ */
+	"subl  $0xc, %esp\n\t"          /* lower again; push/call below will re-align */
+	"movl  %esp, %ecx\n\t"          /* ecx = d */
+	"movl  8(%ebp), %edx\n\t"       /* edx = this */
+	"pushl %edx\n\t"                /* push this. esp % 16 == 0 */
+
+	"movl  0x14(%ebp), %edx\n\t"
+	"call  _invoke_copy_to_stack\n\t"
+	"movl  0x08(%ebp), %ecx\n\t"	/* 'that' */
+	"movl  (%ecx), %edx\n\t"
+	"movl  0x0c(%ebp), %eax\n\t"    /* function index */
+	"leal  (%edx,%eax,4), %edx\n\t"
+	"call  *(%edx)\n\t"
+	"movl  %ebp, %esp\n\t"
+	"popl  %ebp\n\t"
+	"ret\n"
+	".section .drectve\n\t"
+	".ascii \" -export:NS_InvokeByIndex\"\n\t"
+	".text\n\t"
+);
diff --git a/xpcom/reflect/xptcall/md/win32/xptcstubs.cpp b/xpcom/reflect/xptcall/md/win32/xptcstubs.cpp
new file mode 100644
index 000000000..e525aebd7
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/win32/xptcstubs.cpp
@@ -0,0 +1,227 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+#ifndef WIN32
+#error "This code is for Win32 only"
+#endif
+
+extern "C" {
+
+#if !defined(__GNUC__) && !defined(__clang__)
+static
+#endif
+nsresult __stdcall
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex,
+                   uint32_t* args, uint32_t* stackBytesToPop)
+{
+#define PARAM_BUFFER_COUNT     16
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info = nullptr;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    // If anything fails before stackBytesToPop can be set then
+    // the failure is completely catastrophic!
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no method info");
+
+    paramCount = info->GetParamCount();
+
+    // setup variant array pointer
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+    NS_ASSERTION(dispatchParams,"no place for params");
+
+    uint32_t* ap = args;
+    for(i = 0; i < paramCount; i++, ap++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            dp->val.p = (void*) *ap;
+            continue;
+        }
+        // else
+        switch(type)
+        {
+        case nsXPTType::T_I8     : dp->val.i8  = *((int8_t*)  ap);       break;
+        case nsXPTType::T_I16    : dp->val.i16 = *((int16_t*) ap);       break;
+        case nsXPTType::T_I32    : dp->val.i32 = *((int32_t*) ap);       break;
+        case nsXPTType::T_I64    : dp->val.i64 = *((int64_t*) ap); ap++; break;
+        case nsXPTType::T_U8     : dp->val.u8  = *((uint8_t*) ap);       break;
+        case nsXPTType::T_U16    : dp->val.u16 = *((uint16_t*)ap);       break;
+        case nsXPTType::T_U32    : dp->val.u32 = *((uint32_t*)ap);       break;
+        case nsXPTType::T_U64    : dp->val.u64 = *((uint64_t*)ap); ap++; break;
+        case nsXPTType::T_FLOAT  : dp->val.f   = *((float*)   ap);       break;
+        case nsXPTType::T_DOUBLE : dp->val.d   = *((double*)  ap); ap++; break;
+        case nsXPTType::T_BOOL   : dp->val.b   = *((bool*)  ap);       break;
+        case nsXPTType::T_CHAR   : dp->val.c   = *((char*)    ap);       break;
+        case nsXPTType::T_WCHAR  : dp->val.wc  = *((wchar_t*) ap);       break;
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+    *stackBytesToPop = ((uint32_t)ap) - ((uint32_t)args);
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+} // extern "C"
+
+// declspec(naked) is broken in gcc and clang-cl
+#if !defined(__GNUC__) && !defined(__clang__)
+static 
+__declspec(naked)
+void SharedStub(void)
+{
+    __asm {
+        push ebp            // set up simple stack frame
+        mov  ebp, esp       // stack has: ebp/vtbl_index/retaddr/this/args
+        push ecx            // make room for a ptr
+        lea  eax, [ebp-4]   // pointer to stackBytesToPop
+        push eax
+        lea  eax, [ebp+12]  // pointer to args
+        push eax
+        push ecx            // vtbl_index
+        mov  eax, [ebp+8]   // this
+        push eax
+        call PrepareAndDispatch
+        mov  edx, [ebp+4]   // return address
+        mov  ecx, [ebp-4]   // stackBytesToPop
+        add  ecx, 8         // for 'this' and return address
+        mov  esp, ebp
+        pop  ebp
+        add  esp, ecx       // fix up stack pointer
+        jmp  edx            // simulate __stdcall return
+    }
+}
+
+// these macros get expanded (many times) in the file #included below
+#define STUB_ENTRY(n) \
+__declspec(naked) nsresult __stdcall nsXPTCStubBase::Stub##n() \
+{ __asm mov ecx, n __asm jmp SharedStub }
+
+#else
+
+asm(".text\n\t"
+    ".align     4\n\t"
+    "SharedStub:\n\t"
+    "push       %ebp\n\t"
+    "mov        %esp, %ebp\n\t"
+    "push       %ecx\n\t"
+    "lea        -4(%ebp), %eax\n\t"
+    "push       %eax\n\t"
+    "lea        12(%ebp), %eax\n\t"
+    "push       %eax\n\t"
+    "push       %ecx\n\t"
+    "movl       8(%ebp), %eax\n\t"
+    "push       %eax\n\t"
+    "call       _PrepareAndDispatch@16\n\t"
+    "mov        4(%ebp), %edx\n\t"
+    "mov        -4(%ebp), %ecx\n\t"
+    "add        $8, %ecx\n\t"
+    "mov        %ebp, %esp\n\t"
+    "pop        %ebp\n\t"
+    "add        %ecx, %esp\n\t"
+    "jmp        *%edx"
+);
+
+// The clang-cl specific code below is required because mingw uses the gcc name
+// mangling, but clang-cl implements the MSVC name mangling.
+
+#ifdef __clang__
+
+#define STUB_ENTRY(n) \
+asm(".text\n\t" \
+    ".align     4\n\t" \
+    ".globl     \"?Stub" #n "@nsXPTCStubBase@@UAG?AW4nsresult@@XZ\"\n\t" \
+    ".def       \"?Stub" #n "@nsXPTCStubBase@@UAG?AW4nsresult@@XZ\"; \n\t" \
+    ".scl       2\n\t" \
+    ".type      46\n\t" \
+    ".endef\n\t" \
+    "\"?Stub" #n "@nsXPTCStubBase@@UAG?AW4nsresult@@XZ\":\n\t" \
+    "mov $" #n ", %ecx\n\t" \
+    "jmp SharedStub");
+
+#else
+
+#define STUB_ENTRY(n) \
+asm(".text\n\t" \
+    ".align     4\n\t" \
+    ".if	" #n " < 10\n\t" \
+    ".globl     __ZN14nsXPTCStubBase5Stub" #n "Ev@4\n\t" \
+    ".def       __ZN14nsXPTCStubBase5Stub" #n "Ev@4; \n\t" \
+    ".scl       3\n\t" \
+    ".type      46\n\t" \
+    ".endef\n\t" \
+    "__ZN14nsXPTCStubBase5Stub" #n "Ev@4:\n\t" \
+    ".elseif	" #n " < 100\n\t" \
+    ".globl     __ZN14nsXPTCStubBase6Stub" #n "Ev@4\n\t" \
+    ".def       __ZN14nsXPTCStubBase6Stub" #n "Ev@4\n\t" \
+    ".scl       3\n\t" \
+    ".type      46\n\t" \
+    ".endef\n\t" \
+    "__ZN14nsXPTCStubBase6Stub" #n "Ev@4:\n\t" \
+    ".elseif    " #n " < 1000\n\t" \
+    ".globl     __ZN14nsXPTCStubBase7Stub" #n "Ev@4\n\t" \
+    ".def       __ZN14nsXPTCStubBase7Stub" #n "Ev@4\n\t" \
+    ".scl       3\n\t" \
+    ".type      46\n\t" \
+    ".endef\n\t" \
+    "__ZN14nsXPTCStubBase7Stub" #n "Ev@4:\n\t" \
+    ".else\n\t" \
+    ".err	\"stub number " #n " >= 1000 not yet supported\"\n\t" \
+    ".endif\n\t" \
+    "mov $" #n ", %ecx\n\t" \
+    "jmp SharedStub");
+
+#endif
+
+#endif /* __GNUC__ || __clang__ */
+
+#define SENTINEL_ENTRY(n) \
+nsresult __stdcall nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#ifdef _MSC_VER
+#pragma warning(disable : 4035) // OK to have no return value
+#endif
+#include "xptcstubsdef.inc"
+#ifdef _MSC_VER
+#pragma warning(default : 4035) // restore default
+#endif
+
+void
+#ifdef __GNUC__
+__cdecl
+#endif
+xptc_dummy()
+{
+}
diff --git a/xpcom/reflect/xptcall/md/win32/xptcstubs_asm_x86_64.asm b/xpcom/reflect/xptcall/md/win32/xptcstubs_asm_x86_64.asm
new file mode 100644
index 000000000..db2cc16be
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/win32/xptcstubs_asm_x86_64.asm
@@ -0,0 +1,335 @@
+; This Source Code Form is subject to the terms of the Mozilla Public
+; License, v. 2.0. If a copy of the MPL was not distributed with this
+; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+extrn PrepareAndDispatch:PROC
+
+.code
+
+SharedStub PROC FRAME
+    sub     rsp, 104
+    .ALLOCSTACK 104
+    .ENDPROLOG
+
+   ; rcx is this pointer.  Need backup for optimized build
+
+   mov      qword ptr [rsp+88], rcx
+
+   ;
+   ; fist 4 parameters (1st is "this" pointer) are passed in registers.
+   ;
+
+   ; for floating value
+
+    movsd   qword ptr [rsp+64], xmm1
+    movsd   qword ptr [rsp+72], xmm2
+    movsd   qword ptr [rsp+80], xmm3
+
+   ; for integer value
+
+    mov     qword ptr [rsp+40], rdx
+    mov     qword ptr [rsp+48], r8
+    mov     qword ptr [rsp+56], r9
+
+    ;
+    ; Call PrepareAndDispatch function
+    ;
+
+    ; 5th parameter (floating parameters) of PrepareAndDispatch
+
+    lea     r9, qword ptr [rsp+64]
+    mov     qword ptr [rsp+32], r9
+
+    ; 4th parameter (normal parameters) of PrepareAndDispatch
+
+    lea     r9, qword ptr [rsp+40]
+
+    ; 3rd parameter (pointer to args on stack)
+
+    lea     r8, qword ptr [rsp+40+104]
+
+    ; 2nd parameter (vtbl_index)
+
+    mov     rdx, r11
+
+    ; 1st parameter (this) (rcx)
+
+    call    PrepareAndDispatch
+
+    ; restore rcx
+
+    mov     rcx, qword ptr [rsp+88]
+
+    ;
+    ; clean up register
+    ;
+
+    add     rsp, 104+8
+
+    ; set return address
+
+    mov     rdx, qword ptr [rsp-8]
+
+    ; simulate __stdcall return
+
+    jmp     rdx
+
+SharedStub ENDP
+
+
+STUBENTRY MACRO functionname, paramcount
+functionname PROC
+    mov     r11, paramcount
+    jmp     SharedStub
+functionname ENDP
+ENDM
+
+    STUBENTRY ?Stub3@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 3
+    STUBENTRY ?Stub4@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 4
+    STUBENTRY ?Stub5@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 5
+    STUBENTRY ?Stub6@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 6
+    STUBENTRY ?Stub7@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 7
+    STUBENTRY ?Stub8@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 8
+    STUBENTRY ?Stub9@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 9
+    STUBENTRY ?Stub10@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 10
+    STUBENTRY ?Stub11@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 11
+    STUBENTRY ?Stub12@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 12
+    STUBENTRY ?Stub13@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 13
+    STUBENTRY ?Stub14@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 14
+    STUBENTRY ?Stub15@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 15
+    STUBENTRY ?Stub16@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 16
+    STUBENTRY ?Stub17@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 17
+    STUBENTRY ?Stub18@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 18
+    STUBENTRY ?Stub19@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 19
+    STUBENTRY ?Stub20@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 20
+    STUBENTRY ?Stub21@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 21
+    STUBENTRY ?Stub22@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 22
+    STUBENTRY ?Stub23@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 23
+    STUBENTRY ?Stub24@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 24
+    STUBENTRY ?Stub25@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 25
+    STUBENTRY ?Stub26@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 26
+    STUBENTRY ?Stub27@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 27
+    STUBENTRY ?Stub28@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 28
+    STUBENTRY ?Stub29@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 29
+    STUBENTRY ?Stub30@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 30
+    STUBENTRY ?Stub31@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 31
+    STUBENTRY ?Stub32@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 32
+    STUBENTRY ?Stub33@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 33
+    STUBENTRY ?Stub34@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 34
+    STUBENTRY ?Stub35@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 35
+    STUBENTRY ?Stub36@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 36
+    STUBENTRY ?Stub37@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 37
+    STUBENTRY ?Stub38@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 38
+    STUBENTRY ?Stub39@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 39
+    STUBENTRY ?Stub40@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 40
+    STUBENTRY ?Stub41@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 41
+    STUBENTRY ?Stub42@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 42
+    STUBENTRY ?Stub43@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 43
+    STUBENTRY ?Stub44@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 44
+    STUBENTRY ?Stub45@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 45
+    STUBENTRY ?Stub46@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 46
+    STUBENTRY ?Stub47@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 47
+    STUBENTRY ?Stub48@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 48
+    STUBENTRY ?Stub49@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 49
+    STUBENTRY ?Stub50@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 50
+    STUBENTRY ?Stub51@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 51
+    STUBENTRY ?Stub52@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 52
+    STUBENTRY ?Stub53@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 53
+    STUBENTRY ?Stub54@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 54
+    STUBENTRY ?Stub55@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 55
+    STUBENTRY ?Stub56@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 56
+    STUBENTRY ?Stub57@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 57
+    STUBENTRY ?Stub58@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 58
+    STUBENTRY ?Stub59@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 59
+    STUBENTRY ?Stub60@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 60
+    STUBENTRY ?Stub61@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 61
+    STUBENTRY ?Stub62@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 62
+    STUBENTRY ?Stub63@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 63
+    STUBENTRY ?Stub64@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 64
+    STUBENTRY ?Stub65@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 65
+    STUBENTRY ?Stub66@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 66
+    STUBENTRY ?Stub67@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 67
+    STUBENTRY ?Stub68@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 68
+    STUBENTRY ?Stub69@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 69
+    STUBENTRY ?Stub70@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 70
+    STUBENTRY ?Stub71@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 71
+    STUBENTRY ?Stub72@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 72
+    STUBENTRY ?Stub73@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 73
+    STUBENTRY ?Stub74@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 74
+    STUBENTRY ?Stub75@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 75
+    STUBENTRY ?Stub76@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 76
+    STUBENTRY ?Stub77@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 77
+    STUBENTRY ?Stub78@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 78
+    STUBENTRY ?Stub79@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 79
+    STUBENTRY ?Stub80@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 80
+    STUBENTRY ?Stub81@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 81
+    STUBENTRY ?Stub82@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 82
+    STUBENTRY ?Stub83@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 83
+    STUBENTRY ?Stub84@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 84
+    STUBENTRY ?Stub85@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 85
+    STUBENTRY ?Stub86@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 86
+    STUBENTRY ?Stub87@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 87
+    STUBENTRY ?Stub88@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 88
+    STUBENTRY ?Stub89@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 89
+    STUBENTRY ?Stub90@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 90
+    STUBENTRY ?Stub91@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 91
+    STUBENTRY ?Stub92@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 92
+    STUBENTRY ?Stub93@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 93
+    STUBENTRY ?Stub94@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 94
+    STUBENTRY ?Stub95@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 95
+    STUBENTRY ?Stub96@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 96
+    STUBENTRY ?Stub97@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 97
+    STUBENTRY ?Stub98@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 98
+    STUBENTRY ?Stub99@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 99
+    STUBENTRY ?Stub100@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 100
+    STUBENTRY ?Stub101@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 101
+    STUBENTRY ?Stub102@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 102
+    STUBENTRY ?Stub103@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 103
+    STUBENTRY ?Stub104@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 104
+    STUBENTRY ?Stub105@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 105
+    STUBENTRY ?Stub106@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 106
+    STUBENTRY ?Stub107@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 107
+    STUBENTRY ?Stub108@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 108
+    STUBENTRY ?Stub109@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 109
+    STUBENTRY ?Stub110@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 110
+    STUBENTRY ?Stub111@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 111
+    STUBENTRY ?Stub112@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 112
+    STUBENTRY ?Stub113@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 113
+    STUBENTRY ?Stub114@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 114
+    STUBENTRY ?Stub115@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 115
+    STUBENTRY ?Stub116@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 116
+    STUBENTRY ?Stub117@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 117
+    STUBENTRY ?Stub118@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 118
+    STUBENTRY ?Stub119@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 119
+    STUBENTRY ?Stub120@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 120
+    STUBENTRY ?Stub121@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 121
+    STUBENTRY ?Stub122@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 122
+    STUBENTRY ?Stub123@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 123
+    STUBENTRY ?Stub124@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 124
+    STUBENTRY ?Stub125@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 125
+    STUBENTRY ?Stub126@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 126
+    STUBENTRY ?Stub127@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 127
+    STUBENTRY ?Stub128@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 128
+    STUBENTRY ?Stub129@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 129
+    STUBENTRY ?Stub130@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 130
+    STUBENTRY ?Stub131@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 131
+    STUBENTRY ?Stub132@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 132
+    STUBENTRY ?Stub133@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 133
+    STUBENTRY ?Stub134@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 134
+    STUBENTRY ?Stub135@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 135
+    STUBENTRY ?Stub136@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 136
+    STUBENTRY ?Stub137@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 137
+    STUBENTRY ?Stub138@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 138
+    STUBENTRY ?Stub139@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 139
+    STUBENTRY ?Stub140@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 140
+    STUBENTRY ?Stub141@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 141
+    STUBENTRY ?Stub142@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 142
+    STUBENTRY ?Stub143@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 143
+    STUBENTRY ?Stub144@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 144
+    STUBENTRY ?Stub145@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 145
+    STUBENTRY ?Stub146@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 146
+    STUBENTRY ?Stub147@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 147
+    STUBENTRY ?Stub148@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 148
+    STUBENTRY ?Stub149@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 149
+    STUBENTRY ?Stub150@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 150
+    STUBENTRY ?Stub151@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 151
+    STUBENTRY ?Stub152@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 152
+    STUBENTRY ?Stub153@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 153
+    STUBENTRY ?Stub154@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 154
+    STUBENTRY ?Stub155@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 155
+    STUBENTRY ?Stub156@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 156
+    STUBENTRY ?Stub157@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 157
+    STUBENTRY ?Stub158@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 158
+    STUBENTRY ?Stub159@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 159
+    STUBENTRY ?Stub160@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 160
+    STUBENTRY ?Stub161@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 161
+    STUBENTRY ?Stub162@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 162
+    STUBENTRY ?Stub163@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 163
+    STUBENTRY ?Stub164@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 164
+    STUBENTRY ?Stub165@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 165
+    STUBENTRY ?Stub166@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 166
+    STUBENTRY ?Stub167@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 167
+    STUBENTRY ?Stub168@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 168
+    STUBENTRY ?Stub169@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 169
+    STUBENTRY ?Stub170@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 170
+    STUBENTRY ?Stub171@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 171
+    STUBENTRY ?Stub172@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 172
+    STUBENTRY ?Stub173@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 173
+    STUBENTRY ?Stub174@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 174
+    STUBENTRY ?Stub175@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 175
+    STUBENTRY ?Stub176@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 176
+    STUBENTRY ?Stub177@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 177
+    STUBENTRY ?Stub178@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 178
+    STUBENTRY ?Stub179@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 179
+    STUBENTRY ?Stub180@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 180
+    STUBENTRY ?Stub181@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 181
+    STUBENTRY ?Stub182@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 182
+    STUBENTRY ?Stub183@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 183
+    STUBENTRY ?Stub184@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 184
+    STUBENTRY ?Stub185@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 185
+    STUBENTRY ?Stub186@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 186
+    STUBENTRY ?Stub187@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 187
+    STUBENTRY ?Stub188@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 188
+    STUBENTRY ?Stub189@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 189
+    STUBENTRY ?Stub190@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 190
+    STUBENTRY ?Stub191@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 191
+    STUBENTRY ?Stub192@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 192
+    STUBENTRY ?Stub193@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 193
+    STUBENTRY ?Stub194@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 194
+    STUBENTRY ?Stub195@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 195
+    STUBENTRY ?Stub196@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 196
+    STUBENTRY ?Stub197@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 197
+    STUBENTRY ?Stub198@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 198
+    STUBENTRY ?Stub199@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 199
+    STUBENTRY ?Stub200@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 200
+    STUBENTRY ?Stub201@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 201
+    STUBENTRY ?Stub202@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 202
+    STUBENTRY ?Stub203@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 203
+    STUBENTRY ?Stub204@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 204
+    STUBENTRY ?Stub205@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 205
+    STUBENTRY ?Stub206@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 206
+    STUBENTRY ?Stub207@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 207
+    STUBENTRY ?Stub208@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 208
+    STUBENTRY ?Stub209@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 209
+    STUBENTRY ?Stub210@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 210
+    STUBENTRY ?Stub211@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 211
+    STUBENTRY ?Stub212@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 212
+    STUBENTRY ?Stub213@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 213
+    STUBENTRY ?Stub214@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 214
+    STUBENTRY ?Stub215@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 215
+    STUBENTRY ?Stub216@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 216
+    STUBENTRY ?Stub217@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 217
+    STUBENTRY ?Stub218@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 218
+    STUBENTRY ?Stub219@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 219
+    STUBENTRY ?Stub220@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 220
+    STUBENTRY ?Stub221@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 221
+    STUBENTRY ?Stub222@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 222
+    STUBENTRY ?Stub223@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 223
+    STUBENTRY ?Stub224@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 224
+    STUBENTRY ?Stub225@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 225
+    STUBENTRY ?Stub226@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 226
+    STUBENTRY ?Stub227@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 227
+    STUBENTRY ?Stub228@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 228
+    STUBENTRY ?Stub229@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 229
+    STUBENTRY ?Stub230@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 230
+    STUBENTRY ?Stub231@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 231
+    STUBENTRY ?Stub232@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 232
+    STUBENTRY ?Stub233@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 233
+    STUBENTRY ?Stub234@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 234
+    STUBENTRY ?Stub235@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 235
+    STUBENTRY ?Stub236@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 236
+    STUBENTRY ?Stub237@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 237
+    STUBENTRY ?Stub238@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 238
+    STUBENTRY ?Stub239@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 239
+    STUBENTRY ?Stub240@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 240
+    STUBENTRY ?Stub241@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 241
+    STUBENTRY ?Stub242@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 242
+    STUBENTRY ?Stub243@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 243
+    STUBENTRY ?Stub244@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 244
+    STUBENTRY ?Stub245@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 245
+    STUBENTRY ?Stub246@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 246
+    STUBENTRY ?Stub247@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 247
+    STUBENTRY ?Stub248@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 248
+    STUBENTRY ?Stub249@nsXPTCStubBase@@UEAA?AW4nsresult@@XZ, 249
+
+END
diff --git a/xpcom/reflect/xptcall/md/win32/xptcstubs_x86_64.cpp b/xpcom/reflect/xptcall/md/win32/xptcstubs_x86_64.cpp
new file mode 100644
index 000000000..8ff479d1e
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/win32/xptcstubs_x86_64.cpp
@@ -0,0 +1,197 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implement shared vtbl methods. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+/*
+ * This is for Windows XP 64-Bit Edition / Server 2003 for AMD64 or later.
+ */
+
+extern "C" nsresult
+PrepareAndDispatch(nsXPTCStubBase* self, uint32_t methodIndex, uint64_t* args,
+                   uint64_t *gprData, double *fprData)
+{
+#define PARAM_BUFFER_COUNT  16
+//
+// "this" pointer is first parameter, so parameter count is 3.
+//
+#define PARAM_GPR_COUNT   3
+#define PARAM_FPR_COUNT   3
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info = nullptr;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self,"no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info,"no method info");
+
+    paramCount = info->GetParamCount();
+
+    //
+    // setup variant array pointer
+    //
+
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+
+    NS_ASSERTION(dispatchParams,"no place for params");
+
+    uint64_t* ap = args;
+    uint32_t iCount = 0;
+
+    for(i = 0; i < paramCount; i++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            if (iCount < PARAM_GPR_COUNT)
+                dp->val.p = (void*)gprData[iCount++];
+            else
+                dp->val.p = (void*)*ap++;
+
+            continue;
+        }
+        // else
+        switch(type)
+        {
+        case nsXPTType::T_I8:
+           if (iCount < PARAM_GPR_COUNT)
+              dp->val.i8  = (int8_t)gprData[iCount++];
+           else
+              dp->val.i8  = *((int8_t*)ap++);
+           break;
+
+        case nsXPTType::T_I16:
+            if (iCount < PARAM_GPR_COUNT)
+               dp->val.i16  = (int16_t)gprData[iCount++];
+            else
+               dp->val.i16  = *((int16_t*)ap++);
+            break;
+
+        case nsXPTType::T_I32:
+            if (iCount < PARAM_GPR_COUNT)
+               dp->val.i32  = (int32_t)gprData[iCount++];
+            else
+               dp->val.i32  = *((int32_t*)ap++);
+            break;
+
+        case nsXPTType::T_I64:
+            if (iCount < PARAM_GPR_COUNT)
+               dp->val.i64  = (int64_t)gprData[iCount++];
+            else
+               dp->val.i64  = *((int64_t*)ap++);
+            break;
+
+        case nsXPTType::T_U8:
+            if (iCount < PARAM_GPR_COUNT)
+               dp->val.u8  = (uint8_t)gprData[iCount++];
+            else
+               dp->val.u8  = *((uint8_t*)ap++);
+            break;
+
+        case nsXPTType::T_U16:
+            if (iCount < PARAM_GPR_COUNT)
+               dp->val.u16  = (uint16_t)gprData[iCount++];
+            else
+                dp->val.u16  = *((uint16_t*)ap++);
+            break;
+
+        case nsXPTType::T_U32:
+            if (iCount < PARAM_GPR_COUNT)
+               dp->val.u32  = (uint32_t)gprData[iCount++];
+            else
+               dp->val.u32  = *((uint32_t*)ap++);
+            break;
+
+        case nsXPTType::T_U64:
+            if (iCount < PARAM_GPR_COUNT)
+               dp->val.u64  = (uint64_t)gprData[iCount++];
+            else
+               dp->val.u64  = *((uint64_t*)ap++);
+            break;
+
+        case nsXPTType::T_FLOAT:
+             if (iCount < PARAM_FPR_COUNT)
+                // The value in xmm register is already prepared to
+                // be retrieved as a float. Therefore, we pass the
+                // value verbatim, as a double without conversion.
+                dp->val.d  = (double)fprData[iCount++];
+             else
+                dp->val.f  = *((float*)ap++);
+             break;
+
+        case nsXPTType::T_DOUBLE:
+              if (iCount < PARAM_FPR_COUNT)
+                 dp->val.d  = (double)fprData[iCount++];
+              else
+                 dp->val.d  = *((double*)ap++);
+              break;
+
+        case nsXPTType::T_BOOL:
+           if (iCount < PARAM_GPR_COUNT)
+              // We need cast to uint8_t to remove garbage on upper 56-bit
+              // at first.
+              dp->val.b  = (bool)(uint8_t)gprData[iCount++];
+           else
+              dp->val.b  = *((bool*)ap++);
+           break;
+
+        case nsXPTType::T_CHAR:
+           if (iCount < PARAM_GPR_COUNT)
+              dp->val.c  = (char)gprData[iCount++];
+           else
+              dp->val.c  = *((char*)ap++);
+           break;
+
+        case nsXPTType::T_WCHAR:
+           if (iCount < PARAM_GPR_COUNT)
+              dp->val.wc  = (wchar_t)gprData[iCount++];
+           else
+              dp->val.wc  = *((wchar_t*)ap++);
+           break;
+
+        default:
+            NS_ERROR("bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+#define STUB_ENTRY(n)  /* defined in the assembly file */
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ERROR("nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
+
+void
+xptc_dummy()
+{
+}
+
diff --git a/xpcom/reflect/xptcall/md/win32/xptcstubs_x86_64_gnu.cpp b/xpcom/reflect/xptcall/md/win32/xptcstubs_x86_64_gnu.cpp
new file mode 100644
index 000000000..2676334d2
--- /dev/null
+++ b/xpcom/reflect/xptcall/md/win32/xptcstubs_x86_64_gnu.cpp
@@ -0,0 +1,297 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+
+/*
+ * This is for Windows 64 bit (x86_64) using GCC syntax
+ * Code was copied from the MSVC version.
+ */
+
+#if !defined(_AMD64_) || !defined(__GNUC__)
+#  error xptcstubs_x86_64_gnu.cpp being used unexpectedly
+#endif
+
+extern "C" nsresult __attribute__((__used__))
+PrepareAndDispatch(nsXPTCStubBase * self, uint32_t methodIndex,
+                   uint64_t * args, uint64_t * gprData, double *fprData)
+{
+#define PARAM_BUFFER_COUNT  16
+//
+// "this" pointer is first parameter, so parameter count is 3.
+//
+#define PARAM_GPR_COUNT   3
+#define PARAM_FPR_COUNT   3
+
+    nsXPTCMiniVariant paramBuffer[PARAM_BUFFER_COUNT];
+    nsXPTCMiniVariant* dispatchParams = nullptr;
+    const nsXPTMethodInfo* info = nullptr;
+    uint8_t paramCount;
+    uint8_t i;
+    nsresult result = NS_ERROR_FAILURE;
+
+    NS_ASSERTION(self, "no self");
+
+    self->mEntry->GetMethodInfo(uint16_t(methodIndex), &info);
+    NS_ASSERTION(info, "no method info");
+
+    paramCount = info->GetParamCount();
+
+    //
+    // setup variant array pointer
+    //
+
+    if(paramCount > PARAM_BUFFER_COUNT)
+        dispatchParams = new nsXPTCMiniVariant[paramCount];
+    else
+        dispatchParams = paramBuffer;
+
+    NS_ASSERTION(dispatchParams,"no place for params");
+
+    uint64_t* ap = args;
+    uint32_t iCount = 0;
+
+    for(i = 0; i < paramCount; i++)
+    {
+        const nsXPTParamInfo& param = info->GetParam(i);
+        const nsXPTType& type = param.GetType();
+        nsXPTCMiniVariant* dp = &dispatchParams[i];
+
+        if(param.IsOut() || !type.IsArithmetic())
+        {
+            if (iCount < PARAM_GPR_COUNT)
+                dp->val.p = (void*)gprData[iCount++];
+            else
+                dp->val.p = (void*)*ap++;
+
+            continue;
+        }
+        // else
+        switch(type)
+        {
+        case nsXPTType::T_I8:
+           if (iCount < PARAM_GPR_COUNT)
+              dp->val.i8  = (int8_t)gprData[iCount++];
+           else
+              dp->val.i8  = *((int8_t*)ap++);
+           break;
+
+        case nsXPTType::T_I16:
+            if (iCount < PARAM_GPR_COUNT)
+               dp->val.i16  = (int16_t)gprData[iCount++];
+            else
+               dp->val.i16  = *((int16_t*)ap++);
+            break;
+
+        case nsXPTType::T_I32:
+            if (iCount < PARAM_GPR_COUNT)
+               dp->val.i32  = (int32_t)gprData[iCount++];
+            else
+               dp->val.i32  = *((int32_t*)ap++);
+            break;
+
+        case nsXPTType::T_I64:
+            if (iCount < PARAM_GPR_COUNT)
+               dp->val.i64  = (int64_t)gprData[iCount++];
+            else
+               dp->val.i64  = *((int64_t*)ap++);
+            break;
+
+        case nsXPTType::T_U8:
+            if (iCount < PARAM_GPR_COUNT)
+               dp->val.u8  = (uint8_t)gprData[iCount++];
+            else
+               dp->val.u8  = *((uint8_t*)ap++);
+            break;
+
+        case nsXPTType::T_U16:
+            if (iCount < PARAM_GPR_COUNT)
+               dp->val.u16  = (uint16_t)gprData[iCount++];
+            else
+                dp->val.u16  = *((uint16_t*)ap++);
+            break;
+
+        case nsXPTType::T_U32:
+            if (iCount < PARAM_GPR_COUNT)
+               dp->val.u32  = (uint32_t)gprData[iCount++];
+            else
+               dp->val.u32  = *((uint32_t*)ap++);
+            break;
+
+        case nsXPTType::T_U64:
+            if (iCount < PARAM_GPR_COUNT)
+               dp->val.u64  = (uint64_t)gprData[iCount++];
+            else
+               dp->val.u64  = *((uint64_t*)ap++);
+            break;
+
+        case nsXPTType::T_FLOAT:
+             if (iCount < PARAM_FPR_COUNT)
+                dp->val.f  = (float)fprData[iCount++];
+             else
+                dp->val.f  = *((float*)ap++);
+             break;
+
+        case nsXPTType::T_DOUBLE:
+              if (iCount < PARAM_FPR_COUNT)
+                 dp->val.d  = (double)fprData[iCount++];
+              else
+                 dp->val.d  = *((double*)ap++);
+              break;
+
+        case nsXPTType::T_BOOL:
+           if (iCount < PARAM_GPR_COUNT)
+              dp->val.b  = (bool)gprData[iCount++];
+           else
+              dp->val.b  = *((bool*)ap++);
+           break;
+
+        case nsXPTType::T_CHAR:
+           if (iCount < PARAM_GPR_COUNT)
+              dp->val.c  = (char)gprData[iCount++];
+           else
+              dp->val.c  = *((char*)ap++);
+           break;
+
+        case nsXPTType::T_WCHAR:
+           if (iCount < PARAM_GPR_COUNT)
+              dp->val.wc  = (wchar_t)gprData[iCount++];
+           else
+              dp->val.wc  = *((wchar_t*)ap++);
+           break;
+
+        default:
+            NS_ASSERTION(0, "bad type");
+            break;
+        }
+    }
+
+    result = self->mOuter->CallMethod((uint16_t)methodIndex, info, dispatchParams);
+
+    if(dispatchParams != paramBuffer)
+        delete [] dispatchParams;
+
+    return result;
+}
+
+__asm__ (
+  ".text\n"
+  ".intel_syntax noprefix\n"            /* switch to Intel syntax to look like the MSVC assembly */
+  ".globl SharedStub\n"
+  ".def SharedStub ; .scl 3 ; .type 46 ; .endef \n"
+  "SharedStub:\n"
+  "sub     rsp, 104\n"
+
+  /* rcx is this pointer.  Need backup for optimized build */
+
+  "mov      qword ptr [rsp+88], rcx\n"
+
+  /*
+   * fist 4 parameters (1st is "this" pointer) are passed in registers.
+   */
+
+  /* for floating value */
+
+  "movsd   qword ptr [rsp+64], xmm1\n"
+  "movsd   qword ptr [rsp+72], xmm2\n"
+  "movsd   qword ptr [rsp+80], xmm3\n"
+
+  /* for integer value */
+
+  "mov     qword ptr [rsp+40], rdx\n"
+  "mov     qword ptr [rsp+48], r8\n"
+  "mov     qword ptr [rsp+56], r9\n"
+
+  /*
+   * Call PrepareAndDispatch function
+   */
+
+  /* 5th parameter (floating parameters) of PrepareAndDispatch */
+
+  "lea     r9, qword ptr [rsp+64]\n"
+  "mov     qword ptr [rsp+32], r9\n"
+
+  /* 4th parameter (normal parameters) of PrepareAndDispatch */
+
+  "lea     r9, qword ptr [rsp+40]\n"
+
+  /* 3rd parameter (pointer to args on stack) */
+
+  "lea     r8, qword ptr [rsp+40+104]\n"
+
+  /* 2nd parameter (vtbl_index) */
+
+  "mov     rdx, r11\n"
+
+  /* 1st parameter (this) (rcx) */
+
+  "call    PrepareAndDispatch\n"
+
+  /* restore rcx */
+
+  "mov     rcx, qword ptr [rsp+88]\n"
+
+  /*
+   * clean up register
+   */
+
+  "add     rsp, 104+8\n"
+
+  /* set return address */
+
+  "mov     rdx, qword ptr [rsp-8]\n"
+
+  /* simulate __stdcall return */
+
+  "jmp     rdx\n"
+
+  /* back to AT&T syntax */
+  ".att_syntax\n"
+);
+
+#define STUB_ENTRY(n) \
+asm(".intel_syntax noprefix\n" /* this is in intel syntax */ \
+    ".text\n" \
+    ".align 2\n" \
+    ".if        " #n " < 10\n" \
+    ".globl       _ZN14nsXPTCStubBase5Stub" #n "Ev@4\n" \
+    ".def         _ZN14nsXPTCStubBase5Stub" #n "Ev@4\n" \
+    ".scl         3\n" /* private */ \
+    ".type        46\n" /* function returning unsigned int */ \
+    ".endef\n" \
+    "_ZN14nsXPTCStubBase5Stub" #n "Ev@4:\n" \
+    ".elseif    " #n " < 100\n" \
+    ".globl       _ZN14nsXPTCStubBase6Stub" #n "Ev@4\n" \
+    ".def         _ZN14nsXPTCStubBase6Stub" #n "Ev@4\n" \
+    ".scl         3\n" /* private */\
+    ".type        46\n" /* function returning unsigned int */ \
+    ".endef\n" \
+    "_ZN14nsXPTCStubBase6Stub" #n "Ev@4:\n" \
+    ".elseif    " #n " < 1000\n" \
+    ".globl       _ZN14nsXPTCStubBase7Stub" #n "Ev@4\n" \
+    ".def         _ZN14nsXPTCStubBase7Stub" #n "Ev@4\n" \
+    ".scl         3\n" /* private */ \
+    ".type        46\n" /* function returning unsigned int */ \
+    ".endef\n" \
+    "_ZN14nsXPTCStubBase7Stub" #n "Ev@4:\n" \
+    ".else\n" \
+    ".err       \"stub number " #n " >= 1000 not yet supported\"\n" \
+    ".endif\n" \
+    "mov          r11, " #n "\n" \
+    "jmp          SharedStub\n" \
+    ".att_syntax\n" /* back to AT&T syntax */ \
+    "");
+
+#define SENTINEL_ENTRY(n) \
+nsresult nsXPTCStubBase::Sentinel##n() \
+{ \
+    NS_ASSERTION(0,"nsXPTCStubBase::Sentinel called"); \
+    return NS_ERROR_NOT_IMPLEMENTED; \
+}
+
+#include "xptcstubsdef.inc"
+
diff --git a/xpcom/reflect/xptcall/moz.build b/xpcom/reflect/xptcall/moz.build
new file mode 100644
index 000000000..fee7a3352
--- /dev/null
+++ b/xpcom/reflect/xptcall/moz.build
@@ -0,0 +1,23 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += ['md']
+
+SOURCES += [
+    'xptcall.cpp',
+]
+
+EXPORTS += [
+    'xptcall.h',
+    'xptcstubsdecl.inc',
+    'xptcstubsdef.inc',
+]
+
+LOCAL_INCLUDES += [
+    '/xpcom/reflect/xptinfo',
+]
+
+FINAL_LIBRARY = 'xul'
diff --git a/xpcom/reflect/xptcall/porting.html b/xpcom/reflect/xptcall/porting.html
new file mode 100644
index 000000000..0073c604e
--- /dev/null
+++ b/xpcom/reflect/xptcall/porting.html
@@ -0,0 +1,216 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<html>
+<head>
+<title>xptcall Porting Guide</title>
+</head>
+<body bgcolor = "white">
+<h2><center>xptcall Porting Guide</center></h2>
+
+<h3>Overview</h3>
+
+<blockquote>
+
+<a href="http://www.mozilla.org/scriptable/xptcall-faq.html"> xptcall</a> is a
+library that supports both invoking methods on arbitrary xpcom objects and
+implementing classes whose objects can impersonate any xpcom interface. It does
+this using platform specific assembly language code. This code needs to be
+ported to all platforms that want to support xptcall (and thus mozilla).
+
+</blockquote>
+
+<h3>The tree</h3>
+
+<blockquote>
+<pre>
+<a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall">mozilla/xpcom/reflect/xptcall</a>
+  +--<a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/public">public</a>  // exported headers
+  +--<a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/src">src</a>  // core source
+  |  \--<a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md">md</a>  // platform specific parts
+  |     +--<a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md/mac">mac</a>  // mac ppc
+  |     +--<a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md/unix">unix</a>  // all unix
+  |     \--<a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md/win32">win32</a>  // win32
+  |     +--<a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md/test">test</a>  // simple tests to get started
+  \--<a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/tests">tests</a>  // full tests via api
+</pre>
+
+Porters are free to create subdirectories under the base <code>md</code>
+directory for their given platforms and to integrate into the build system as
+appropriate for their platform.
+
+</blockquote>
+
+<h3>Theory of operation</h3>
+
+<blockquote>
+
+There are really two pieces of functionality: <i>invoke</i> and <i>stubs</i>...
+
+<p>
+
+The <b><i>invoke</i></b> functionality requires the implementation of the
+following on each platform (from <a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/xptcall.h">xptcall/xptcall.h</a>):
+
+<pre>
+XPTC_PUBLIC_API(nsresult)
+NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                   uint32_t paramCount, nsXPTCVariant* params);
+</pre>
+
+Calling code is expected to supply an array of <code>nsXPTCVariant</code>
+structs. These are discriminated unions describing the type and value of each
+parameter of the target function. The platform specific code then builds a call
+frame and invokes the method indicated by the index <code>methodIndex</code> on
+the xpcom interface <code>that</code>.
+
+<p>
+
+Here are examples of this implementation for 
+<a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md/win32/xptcinvoke.cpp">Win32</a>
+and 
+<a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md/unix/xptcinvoke_unixish_x86.cpp">Linux x86, NetBSD x86, and FreeBSD</a>.
+
+Both of these implementations use the basic strategy of: figure out how much
+stack space is needed for the params, make the space in a new frame, copy the
+params to that space, invoke the method, cleanup and return. C++ is used where
+appropriate, Assembly language is used where necessary. Inline assembly language is used here,
+but it is equally valid to use separate assembly language source files. Porters
+can decide how best to do this for their platforms.
+
+<p>
+
+The <b><i>stubs</i></b> functionality is more complex. The goal here is a class
+whose vtbl can look like the vtbl of any arbitrary xpcom interface. Objects of
+this class can then be built to impersonate any xpcom object. The base interface
+for this is (from <a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/xptcall.h">xptcall/xptcall.h</a>):
+
+<pre>
+class nsXPTCStubBase : public nsISupports
+{
+public:
+    // Include generated vtbl stub declarations.
+    // These are virtual and *also* implemented by this class..
+#include "xptcstubsdecl.inc"
+
+    // The following methods must be provided by inheritor of this class.
+
+    // return a refcounted pointer to the InterfaceInfo for this object
+    // NOTE: on some platforms this MUST not fail or we crash!
+    NS_IMETHOD GetInterfaceInfo(nsIInterfaceInfo** info) = 0;
+
+    // call this method and return result
+    NS_IMETHOD CallMethod(uint16_t methodIndex,
+                          const nsXPTMethodInfo* info,
+                          nsXPTCMiniVariant* params) = 0;
+};
+</pre>
+
+Code that wishes to make use of this <i>stubs</i> functionality (such as 
+<a href="http://www.mozilla.org/scriptable/">XPConnect</a>) implement a class
+which inherits from <code>nsXPTCStubBase</code> and implements the
+<code>GetInterfaceInfo</code> and <code>CallMethod</code> to let the
+platform specific code know how to get interface information and how to dispatch methods
+once their parameters have been pulled out of the platform specific calling
+frame.
+
+<p>
+
+Porters of this functionality implement the platform specific code for the
+<i>stub</i> methods that fill the vtbl for this class. The idea here is that the
+class has a vtbl full of a large number of generic stubs. All instances of this
+class share that vtbl and the same stubs. The stubs forward calls to a platform
+specific method that uses the interface information supplied by
+the overridden <code>GetInterfaceInfo</code> to extract the parameters and build
+an array of platform independent <code>nsXPTCMiniVariant</code> structs which
+are in turn passed on to the overridden <code>CallMethod</code>. The
+platform dependent code is responsible for doing any cleanup and returning.
+
+<p>
+
+The stub methods are declared in <a
+href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/xptcstubsdecl.inc">xptcall/xptcstubsdecl.inc</a>.
+These are '#included' into the declaration of <code>nsXPTCStubBase</code>. A
+similar include file (<a
+href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/xptcstubsdef.inc">xptcall/xptcstubsdef.inc</a>)
+is expanded using platform specific macros to define the stub functions. These
+'.inc' files are checked into cvs. However, they can be regenerated as necessary
+(i.e. to change the number of stubs or to change their specific declaration)
+using the Perl script  <a
+href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/genstubs.pl">xptcall/genstubs.pl</a>.
+
+<p>
+
+Here are examples of this implementation for  <a
+href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md/win32/xptcstubs.cpp">Win32</a>
+and  <a
+href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md/unix/xptcstubs_unixish_x86.cpp">Linux x86, NetBSD x86, and FreeBSD</a>.
+Both of these examples use inline assembly language. That is just how I
+decided to do it. You can do it as you choose.
+
+<p>
+
+The Win32 version is somewhat tighter because the __declspec(naked) feature
+allows for very small stubs. However, the __stdcall requires the callee to clean
+up the stack, so it is imperative that the interface information scheme allow
+the code to determine the correct stack pointer fixup for return without fail,
+else the process will crash.
+
+<p>
+
+I opted to use inline assembler for the gcc Linux x86 port. I ended up with
+larger stubs than I would have preferred rather than battle the compiler over
+what would happen to the stack before my asm code began running.
+
+<p>
+
+I believe that the non-assembly parts of these files can be copied and reused
+with minimal (but not zero) platform specific tweaks. Feel free to copy and
+paste as necessary. Please remember that safety and reliability are more
+important than speed optimizations. This code is primarily used to connect XPCOM
+components with JavaScript; function call overhead is a <b>tiny</b> part of the
+time involved.
+
+<p>
+
+I put together 
+<a
+href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md/test">xptcall/md/test
+</a> as a place to evolve the basic functionality as a port is coming together.
+Not all of the functionality is exercised, but it is a place to get started. 
+<a
+href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/tests">xptcall/tests
+</a> has an api level test for <code>NS_InvokeByIndex</code>, but no tests for
+the <i>stubs</i> functionality. Such a test ought to be written, but this has not
+yet been done.
+
+<p>
+
+A full 'test' at this point requires building the client and running the
+XPConnect test called <i>TestXPC</i> in
+<a
+href="http://lxr.mozilla.org/mozilla/source/js/xpconnect/tests">mozilla/js/xpconnect/tests
+</a>.
+
+<p>
+
+Getting these ports done is very important. Please let <a
+href="mailto:jband@netscape.com">me</a> know if you are interested in doing one.
+I'll answer any questions as I get them.
+
+<p>
+
+<a
+href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/status.html">
+Porting Status
+</a>
+
+</blockquote>
+
+<hr>
+<b>Author:</b> <a href="mailto:jband@netscape.com">John Bandhauer &lt;jband@netscape.com&gt;</a><br>
+<b>Last modified:</b> 31 May 1999
+
+</body>
+</html>
diff --git a/xpcom/reflect/xptcall/status.html b/xpcom/reflect/xptcall/status.html
new file mode 100644
index 000000000..65de20596
--- /dev/null
+++ b/xpcom/reflect/xptcall/status.html
@@ -0,0 +1,412 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<html>
+<head>
+<title>xptcall Porting Status</title>
+</head>
+<body bgcolor = "white">
+<h2><center>xptcall Porting Status</center></h2>
+
+<h3>What is this?</h3>
+
+This is a status page for the multiplatform porting of xptcall.
+xptcall has a 
+<a href="http://www.mozilla.org/scriptable/xptcall-faq.html">FAQ</a>
+and a 
+<a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/porting.html">Porting Guide</a>.
+
+<p>
+
+This is being maintained by <a href="mailto:jband@netscape.com">John Bandhauer &lt;jband@netscape.com&gt;</a>.
+Feel free to email me with questions or to volunteer to contribute xptcall code for any platform.
+
+<p>
+
+<a href="mailto:shaver@mozilla.org">Mike Shaver &lt;shaver@mozilla.org&gt;</a> 
+is the best contact regarding 'nix (Unix, Linux, Finux, etc.) ports of xptcall.
+
+<h3>Status</h3>
+
+<table BORDER="1">
+<TR align="left" BGCOLOR="yellow">
+<TH>Status</TH>
+<TH>Platform</TH>
+<TH><img src="http://tinderbox.mozilla.org/star.gif">Contributors and <font color="red"><b>?</b></font> Possible Contributors</TH>
+<TH>Notes</TH>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>Win32 x86</TD>
+<TD><img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:jband@netscape.com">John Bandhauer &lt;jband@netscape.com&gt;</a>
+</TD>
+<TD>
+<a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md/win32">win32</a></TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>Linux x86</TD>
+<TD><img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:jband@netscape.com">John Bandhauer &lt;jband@netscape.com&gt;</a><br>
+<img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:drepper@cygnus.com">Ulrich Drepper &lt;drepper@cygnus.com&gt;</a>
+</TD>
+<TD><a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md/unix">unix</a>
+</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>FreeBSD and NetBSD x86</TD>
+<TD><img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:toshok@hungry.com">Christoph Toshok &lt;toshok@hungry.com&gt;</a>,<BR>
+<img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:jband@netscape.com">John Bandhauer &lt;jband@netscape.com&gt;</a></TD>
+<TD><a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md/unix">unix</a> (same as Linux 86 code)</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>BSD/OS x86</TD>
+<TD><img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:bert_driehuis@nl.compuware.com">Bert Driehuis &lt;bert_driehuis@nl.compuware.com&gt;</a></TD>
+<TD><a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md/unix">unix</a> (same as Linux 86 code)
+Bert contributed patches that *should* do the right thing for all the unixish-x86
+versions of this code for GCC 2.7 or 2.8 vs. EGCS 1.1. He notes that the vtbl 
+scheme is different. He is hoping that others will help test the changes using 
+these two compilers on the various platforms where this same code is used. 
+<a href="news://news.mozilla.org/372DD257.4248C821%40nl.compuware.com">Bert's details</a>
+</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>Mac PPC</TD>
+<TD><img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+ <a href="mailto:rogerl@netscape.com">Roger Lawrence &lt;rogerl@netscape.com&gt;</a>,<BR>
+<img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:beard@netscape.com">Patrick Beard &lt;beard@netscape.com&gt;</a>
+</TD>
+<TD><a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md/mac">mac</a> (passing tests and checked in)</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>Solaris Sparc</TD>
+<TD><img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:rogerl@netscape.com">Roger Lawrence &lt;rogerl@netscape.com&gt;</a>,<BR>
+<img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:mcafee@netscape.com">Chris McAfee &lt;mcafee@netscape.com&gt;</a>
+</TD>
+<TD><a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md/unix">unix</a> This is checked in and working.</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>Solaris Sparc v9 (64bit)</TD>
+<TD><img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:pavlov@netscape.com">Stuart Parmenter &lt;pavlov@netscape.com&gt;</a>,<BR>
+<img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:cls@seawood.org">Chris Seawood &lt;cls@seawood.org&gt;</a>
+</TD>
+<TD><a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md/unix">unix</a> This is checked in and (pavlov claims!) working.</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>OS/2</TD>
+<TD><img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:mjf35@cam.ac.uk">John Fairhurst &lt;mjf35@cam.ac.uk&gt;</a></TD>
+<TD>I never heard exactly who did what. But mozilla has been working on OS/2 
+for a long time now.
+</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>OpenVMS Alpha</TD>
+<TD><img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:colin@theblakes.com">Colin R. Blake &lt;colin@theblakes.com&gt;</a></TD>
+<TD>
+Colin says this is passing all the tests on OpenVMS Alpha!
+</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>NT Alpha</TD>
+<TD><img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:bob@guiduck.com">bob meader &lt;bob@guiduck.com&gt;</a></TD>
+<TD>
+bob writes:<br>
+Enclosed is xptcall for alpha/nt target..
+<p>
+It is a variation of the IRIS port (only targeted for win32).
+<p>
+Notice the last 2 files (the change to mozilla\xpcom\build\makefile.win and
+mozilla\xpcom\build) are needed because I was unable to figure how to do a
+"declspecexport" from the assembler ASAXP ... if some knows how to do that then
+those last 2 files won't be needed.
+<p>
+I have had someone look over this code at bridge.com (the entry point to
+compaq/gem compiler team) and this code was given the OK. I consider it "done".
+<p>
+This code lives in the files where the name includes 'alpha' in the <a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md/win32">win32</a> directory.<BR>
+</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>Linux ARM</TD>
+<TD><img alt="Started" title="Started" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:sh990154@mail.uni-greifswald.de">Stefan Hanske&lt;sh990154@mail.uni-greifswald.de&gt;</a><BR>
+<font color="red"><b>?</b></font>
+<a href="mailto:willy@bofh.ai">Matthew Wilcox &lt;willy@bofh.ai&gt;</a></TD>
+<TD>
+Stefan's code is checked in and he says it is working.
+</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>Linux Sparc</TD>
+<TD>
+<img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:anton@progsoc.uts.edu.au">Anton Blanchard &lt;anton@progsoc.uts.edu.au&gt;</a>,
+<BR>
+<img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:rogerl@netscape.com">Roger Lawrence &lt;rogerl@netscape.com&gt;</a>,
+<BR>
+<img  alt="Maybe" title="Maybe" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:ehle.3@osu.eduehle.3@osu.edu">Brandon Ehle &lt;ehle.3@osu.edu&gt;</a>
+</TD>
+<TD>
+Anton contributed patches to Roger's Sparc code. Anton says it works and passes the tests!<b>
+(24-Aug-1999) Brandon writes: I've finished testing XPTCALL Sparc Linux on 12 different Sparc machines and it checks out good.
+</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>Linux PPC</TD>
+<TD> 
+<img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:beard@netscape.com">Patrick Beard &lt;beard@netscape.com&gt;</a><BR>
+<img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:waterson@netscape.com">Chris Waterson &lt;waterson@netscape.com&gt;</a><BR>
+<img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:Franz.Sirl-kernel@lauterbach.com">Franz Sirl &lt;Franz.Sirl-kernel@lauterbach.com&gt;</a><BR>
+<font color="red"><b>?</b></font> 
+<a href="mailto:jsproul@condor.fddi.wesleyan.edu">Jason Y. Sproul &lt;jsproul@condor.fddi.wesleyan.edu&gt;</a><BR>
+ <font color="red"><b>?</b></font> 
+ <a href="mailto:darkmane@w-link.net">Sean Chitwood &lt;darkmane@w-link.net&gt;</a></TD>
+<TD>
+waterson said: <b>Mozilla runs on Linux/PPC</b>
+</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>Linux Alpha</TD>
+<TD>
+<img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:glen.nakamura@usa.net">Glen Nakamura &lt;glen.nakamura@usa.net&gt;</a><BR>
+<img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:morrildl@nycap.rr.com">Dan Morril &lt;morrildl@nycap.rr.com&gt;</a><BR>
+</TD>
+<TD>
+Glen writes:
+<p>
+I am attaching a patch which contains my Linux Alpha xptcall code.
+It passes TestXPTCInvoke and TestXPC on my machine which runs
+kernel 2.2.7, glibc 2.1.1, and egcs 1.1.2.  I have not tested it
+with older GNU compilers such as gcc 2.8.x.  From looking at the
+Linux x86 code, I gather that the vtable layout is a little different
+for those compilers and the code will need minor modifications
+in order to work properly.
+<p>
+I am not sure how much of the code can be used for OpenVMS Alpha
+and/or Digital UNIX.  Currently the code is dependent on the g++
+name mangling convention and a few GNU extensions so I'm not sure
+how useful it will be for the other systems.  Hopefully the
+comments in the code are detailed enough to help people attempting
+a port.
+<p>
+</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>SunOS x86</TD>
+<TD> 
+<img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:aljones@lbl.gov">Arthur Jones &lt;aljones@lbl.gov&gt;</a><BR>
+<font color="red"><b>?</b></font> 
+<a href="mailto:ppokorny@mindspring.com">Philip Pokorny &lt;ppokorny@mindspring.com&gt;</a><BR>
+</TD>
+<TD>
+The word I hear is that this is working and done
+</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>HP-UX</TD>
+<TD>
+<img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:wang@cup.hp.com">Thomas Wang &lt;wang@cup.hp.com&gt;</a><BR>
+<img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:mgleeson1@netscape.com">Mike Gleeson &lt;mgleeson1@netscape.com&gt;</a>
+</TD>
+<TD>I hear that this code is checked in and working. Though, there is some 
+doubt - see bug 
+#<a href="http://bugzilla.mozilla.org/show_bug.cgi?id=17997">17997</a>
+</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>AIX PPC</TD>
+<TD><img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:jdunn@netscape.com">Jim Dunn &lt;jdunn@netscape.com&gt;</a></TD>
+<TD>Philip K. Warren writes: <BR>
+
+We have gone through several releases of AIX without any problems.
+</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>Irix</TD>
+<TD><img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:jasonh@m7.engr.sgi.com">Jason Heirtzler &lt;jasonh@m7.engr.sgi.com&gt;</a><BR>
+</TD>
+<TD>Jason has declared this done. Jason is no longer working at SGI and will 
+not be maintaining this code. There is some doubt as to whether or not this is 
+working for everyone - see bug 
+#<a href="http://bugzilla.mozilla.org/show_bug.cgi?id=10061">10061</a>. 
+<a href="mailto:shaver@mozilla.org">Mike&nbsp;Shaver&nbsp;&lt;shaver@mozilla.org&gt;</a> 
+is the interim maintainer until someone more suitable can be found.
+</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>BeOS x86</TD>
+<TD><img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:duncan@be.com">Duncan Wilcox &lt;duncan@be.com&gt;</a><BR>
+</TD>
+<TD>
+<a href="http://lxr.mozilla.org/mozilla/source/xpcom/reflect/xptcall/md/unix">unix</a> (yet another reuse of the Linux 86 code!)<BR>
+Duncan says this is all working. He did the code for old cfront style 'this' adjustment for others to use too!
+</TD>
+</TR>
+
+<TR>
+<TD bgcolor="red"><font color="white"><b>HELP!</b></font></TD>
+<TD>BeOS PPC</TD>
+<TD align="center">-</TD>
+<TD align="center">-</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>Compaq Tru64 UNIX (Digital UNIX)</TD>
+<TD><img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:streeter@zk3.dec.com">Steve Streeter &lt;streeter@zk3.dec.com&gt;</a><BR>
+</TD>
+<TD>Code passes the tests and is checked in.</TD>
+</TR>
+
+<TR>
+<TD bgcolor="khaki"><font color="black"><b>Working</b></font></TD>
+<TD>Neutrio x86</TD>
+<TD><img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:Jerry.Kirk@Nexwarecorp.com">Jerry L. Kirk &lt;Jerry.Kirk@Nexwarecorp.com&gt;</a><BR>
+</TD>
+<TD>
+Patches for xptc*_unixish_x86.cpp checked in. Waiting for verification that this is really finished. 
+</TD>
+</TR>
+
+<TR>
+<TD bgcolor="khaki"><font color="black"><b>Investigating</b></font></TD>
+<TD>SCO UW7 and OSR5</TD>
+<TD>
+<img alt="Investigating" title="Investigating" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:jkj@sco.com">J. Kean Johnston &lt;jkj@sco.com&gt;</a><BR>
+<img alt="Investigating" title="Investigating" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:evanh@sco.com">Evan Hunt &lt;evanh@sco.com&gt;</a><BR>
+</TD>
+<TD>Recent (Feb-2001) email from jkj@sco.com suggests that work will be occuring soon.</TD>
+</TR>
+
+<TR>
+<TD bgcolor="khaki"><font color="black"><b>Works</b></font></TD>
+<TD>NetBSD/m68k</TD>
+<TD><img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:khym@bga.com">Dave Huang &lt;khym@bga.com&gt;</a><BR>
+</TD>
+<TD>
+Dave's changes are in the tree. Waiting for verification that it is really finished.</TD>
+</TR>
+
+<TR>
+<TD bgcolor="khaki"><font color="black"><b>Partially Working</b></font></TD>
+<TD>NetBSD/arm32</TD>
+<TD><img alt="Investigating" title="Investigating" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:mpumford@black-star.demon.co.uk">Mike Pumford &lt;mpumford@black-star.demon.co.uk&gt;</a>
+</TD>
+<TD>Mike writes:<BR>
+I have started porting to the platform based on the code for Linux ARM. The 
+InvokeByIndex code works correctly when used with TestXPTCInvoke. I am 
+currently working on making TestXPC function correctly.
+<P>
+I am doing the porting work with egcs-1.1.2 on NetBSD 1.4P (NetBSD-current 
+snapshot from a couple of days ago).
+</TD>
+</TR>
+
+<TR>
+<TD bgcolor="green"><font color="white"><b>Done</b></font></TD>
+<TD>Linux ia64</TD>
+<TD><img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+HP<br>
+<img alt="Contributed code!" title="Contributed code!" src="http://tinderbox.mozilla.org/star.gif">
+<a href="mailto:drepper@redhat.com">Ulrich Drepper &lt;drepper@redhat.com&gt;</a>
+</TD>
+<TD><a href="https://bugzilla.mozilla.org/show_bug.cgi?id=40950#c15">bug 40950 comment 15</a></TD>
+</TR>
+
+
+<TR>
+<TD bgcolor="red"><font color="white"><b>HELP!</b></font></TD>
+<TD>All others!</TD>
+<TD align="center">-</TD>
+<TD align="center">-</TD>
+</TR>
+
+
+</table>
+
+<p>
+
+<b>Note:</b> I've used the symbol (<font color="red"><b>?</b></font>) to 
+indicate people who have expressed an interest in <i>possibly</i> contributing code. 
+Just because these people are listed here does not mean that they have commited
+themselves to do the work. If <b>you</b> would like to contribute then let me 
+know. Feel free to email these folks and offer to help or find out what's going 
+on. We're all in this together.
+
+<p>
+
+<hr>
+<b>Author:</b> <a href="mailto:jband@netscape.com">John Bandhauer &lt;jband@netscape.com&gt;</a><br>
+<b>Last modified:</b> 3 February 2003
+
+</body>
+</html>
diff --git a/xpcom/reflect/xptcall/xptcall.cpp b/xpcom/reflect/xptcall/xptcall.cpp
new file mode 100644
index 000000000..1ea0ac34d
--- /dev/null
+++ b/xpcom/reflect/xptcall/xptcall.cpp
@@ -0,0 +1,82 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* entry point wrappers. */
+
+#include "xptcprivate.h"
+#include "xptiprivate.h"
+#include "mozilla/XPTInterfaceInfoManager.h"
+#include "nsPrintfCString.h"
+
+using namespace mozilla;
+
+NS_IMETHODIMP
+nsXPTCStubBase::QueryInterface(REFNSIID aIID,
+                               void **aInstancePtr)
+{
+    if (aIID.Equals(mEntry->IID())) {
+        NS_ADDREF_THIS();
+        *aInstancePtr = static_cast<nsISupports*>(this);
+        return NS_OK;
+    }
+
+    return mOuter->QueryInterface(aIID, aInstancePtr);
+}
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsXPTCStubBase::AddRef()
+{
+    return mOuter->AddRef();
+}
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsXPTCStubBase::Release()
+{
+    return mOuter->Release();
+}
+
+EXPORT_XPCOM_API(nsresult)
+NS_GetXPTCallStub(REFNSIID aIID, nsIXPTCProxy* aOuter,
+                  nsISomeInterface* *aResult)
+{
+    if (NS_WARN_IF(!aOuter) || NS_WARN_IF(!aResult))
+        return NS_ERROR_INVALID_ARG;
+
+    XPTInterfaceInfoManager *iim =
+        XPTInterfaceInfoManager::GetSingleton();
+    if (NS_WARN_IF(!iim))
+        return NS_ERROR_NOT_INITIALIZED;
+
+    xptiInterfaceEntry *iie = iim->GetInterfaceEntryForIID(&aIID);
+    if (!iie || !iie->EnsureResolved() || iie->GetBuiltinClassFlag())
+        return NS_ERROR_FAILURE;
+
+    if (iie->GetHasNotXPCOMFlag()) {
+#ifdef DEBUG
+        nsPrintfCString msg("XPTCall will not implement interface %s because of [notxpcom] members.", iie->GetTheName());
+        NS_WARNING(msg.get());
+#endif
+        return NS_ERROR_FAILURE;
+    }
+
+    *aResult = new nsXPTCStubBase(aOuter, iie);
+    return NS_OK;
+}
+
+EXPORT_XPCOM_API(void)
+NS_DestroyXPTCallStub(nsISomeInterface* aStub)
+{
+    nsXPTCStubBase* stub = static_cast<nsXPTCStubBase*>(aStub);
+    delete(stub);
+}
+
+EXPORT_XPCOM_API(size_t)
+NS_SizeOfIncludingThisXPTCallStub(const nsISomeInterface* aStub,
+                                  mozilla::MallocSizeOf aMallocSizeOf)
+{
+    // We could cast aStub to nsXPTCStubBase, but that class doesn't seem to own anything,
+    // so just measure the size of the object itself.
+    return aMallocSizeOf(aStub);
+}
diff --git a/xpcom/reflect/xptcall/xptcall.h b/xpcom/reflect/xptcall/xptcall.h
new file mode 100644
index 000000000..1f2367b5d
--- /dev/null
+++ b/xpcom/reflect/xptcall/xptcall.h
@@ -0,0 +1,193 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Public declarations for xptcall. */
+
+#ifndef xptcall_h___
+#define xptcall_h___
+
+#include "nscore.h"
+#include "nsISupports.h"
+#include "xpt_struct.h"
+#include "xptinfo.h"
+#include "js/Value.h"
+#include "mozilla/MemoryReporting.h"
+
+struct nsXPTCMiniVariant
+{
+// No ctors or dtors so that we can use arrays of these on the stack
+// with no penalty.
+    union
+    {
+        int8_t    i8;
+        int16_t   i16;
+        int32_t   i32;
+        int64_t   i64;
+        uint8_t   u8;
+        uint16_t  u16;
+        uint32_t  u32;
+        uint64_t  u64;
+        float     f;
+        double    d;
+        bool      b;
+        char      c;
+        char16_t wc;
+        void*     p;
+
+        // Types below here are unknown to the assembly implementations, and
+        // therefore _must_ be passed with indirect semantics. We put them in
+        // the union here for type safety, so that we can avoid void* tricks.
+        JS::Value j;
+    } val;
+};
+
+struct nsXPTCVariant : public nsXPTCMiniVariant
+{
+// No ctors or dtors so that we can use arrays of these on the stack
+// with no penalty.
+
+    // inherits 'val' here
+    void*     ptr;
+    nsXPTType type;
+    uint8_t   flags;
+
+    enum
+    {
+        //
+        // Bitflag definitions
+        //
+
+        // Indicates that ptr (above, and distinct from val.p) is the value that
+        // should be passed on the stack.
+        //
+        // In theory, ptr could point anywhere. But in practice it always points
+        // to &val. So this flag is used to pass 'val' by reference, letting us
+        // avoid the extra allocation we would incur if we were to use val.p.
+        //
+        // Various parts of XPConnect assume that ptr==&val, so we enforce it
+        // explicitly with SetIndirect() and IsIndirect().
+        //
+        // Since ptr always points to &val, the semantics of this flag are kind of
+        // dumb, since the ptr field is unnecessary. But changing them would
+        // require changing dozens of assembly files, so they're likely to stay
+        // the way they are.
+        PTR_IS_DATA    = 0x1,
+
+        // Indicates that the value we hold requires some sort of cleanup (memory
+        // deallocation, interface release, JS::Value unrooting, etc). The precise
+        // cleanup that is performed depends on the 'type' field above.
+        // If the value is an array, this flag specifies whether the elements
+        // within the array require cleanup (we always clean up the array itself,
+        // so this flag would be redundant for that purpose).
+        VAL_NEEDS_CLEANUP = 0x2
+    };
+
+    void ClearFlags()         {flags = 0;}
+    void SetIndirect()        {ptr = &val; flags |= PTR_IS_DATA;}
+    void SetValNeedsCleanup() {flags |= VAL_NEEDS_CLEANUP;}
+
+    bool IsIndirect()         const  {return 0 != (flags & PTR_IS_DATA);}
+    bool DoesValNeedCleanup() const  {return 0 != (flags & VAL_NEEDS_CLEANUP);}
+
+    // Internal use only. Use IsIndirect() instead.
+    bool IsPtrData()       const  {return 0 != (flags & PTR_IS_DATA);}
+
+    void Init(const nsXPTCMiniVariant& mv, const nsXPTType& t, uint8_t f)
+    {
+        type = t;
+        flags = f;
+
+        if(f & PTR_IS_DATA)
+        {
+            ptr = mv.val.p;
+            val.p = nullptr;
+        }
+        else
+        {
+            ptr = nullptr;
+            val.p = nullptr; // make sure 'val.p' is always initialized
+            switch(t.TagPart()) {
+              case nsXPTType::T_I8:                val.i8  = mv.val.i8;  break;
+              case nsXPTType::T_I16:               val.i16 = mv.val.i16; break;
+              case nsXPTType::T_I32:               val.i32 = mv.val.i32; break;
+              case nsXPTType::T_I64:               val.i64 = mv.val.i64; break;
+              case nsXPTType::T_U8:                val.u8  = mv.val.u8;  break;
+              case nsXPTType::T_U16:               val.u16 = mv.val.u16; break;
+              case nsXPTType::T_U32:               val.u32 = mv.val.u32; break;
+              case nsXPTType::T_U64:               val.u64 = mv.val.u64; break;
+              case nsXPTType::T_FLOAT:             val.f   = mv.val.f;   break;
+              case nsXPTType::T_DOUBLE:            val.d   = mv.val.d;   break;
+              case nsXPTType::T_BOOL:              val.b   = mv.val.b;   break;
+              case nsXPTType::T_CHAR:              val.c   = mv.val.c;   break;
+              case nsXPTType::T_WCHAR:             val.wc  = mv.val.wc;  break;
+              case nsXPTType::T_VOID:              /* fall through */
+              case nsXPTType::T_IID:               /* fall through */
+              case nsXPTType::T_DOMSTRING:         /* fall through */
+              case nsXPTType::T_CHAR_STR:          /* fall through */
+              case nsXPTType::T_WCHAR_STR:         /* fall through */
+              case nsXPTType::T_INTERFACE:         /* fall through */
+              case nsXPTType::T_INTERFACE_IS:      /* fall through */
+              case nsXPTType::T_ARRAY:             /* fall through */
+              case nsXPTType::T_PSTRING_SIZE_IS:   /* fall through */
+              case nsXPTType::T_PWSTRING_SIZE_IS:  /* fall through */
+              case nsXPTType::T_UTF8STRING:        /* fall through */
+              case nsXPTType::T_CSTRING:           /* fall through */              
+              default:                             val.p   = mv.val.p;   break;
+            }
+        }
+    }
+};
+
+class nsIXPTCProxy : public nsISupports
+{
+public:
+    NS_IMETHOD CallMethod(uint16_t aMethodIndex,
+                          const XPTMethodDescriptor *aInfo,
+                          nsXPTCMiniVariant *aParams) = 0;
+};
+
+/**
+ * This is a typedef to avoid confusion between the canonical
+ * nsISupports* that provides object identity and an interface pointer
+ * for inheriting interfaces that aren't known at compile-time.
+ */
+typedef nsISupports nsISomeInterface;
+
+/**
+ * Get a proxy object to implement the specified interface.
+ *
+ * @param aIID    The IID of the interface to implement.
+ * @param aOuter  An object to receive method calls from the proxy object.
+ *                The stub forwards QueryInterface/AddRef/Release to the
+ *                outer object. The proxy object does not hold a reference to
+ *                the outer object; it is the caller's responsibility to
+ *                ensure that this pointer remains valid until the stub has
+ *                been destroyed.
+ * @param aStub   Out parameter for the new proxy object. The object is
+ *                not addrefed. The object never destroys itself. It must be
+ *                explicitly destroyed by calling
+ *                NS_DestroyXPTCallStub when it is no longer needed.
+ */
+XPCOM_API(nsresult)
+NS_GetXPTCallStub(REFNSIID aIID, nsIXPTCProxy* aOuter,
+                  nsISomeInterface* *aStub);
+
+/**
+ * Destroys an XPTCall stub previously created with NS_GetXPTCallStub.
+ */
+XPCOM_API(void)
+NS_DestroyXPTCallStub(nsISomeInterface* aStub);
+
+/**
+ * Measures the size of an XPTCall stub previously created with NS_GetXPTCallStub.
+ */
+XPCOM_API(size_t)
+NS_SizeOfIncludingThisXPTCallStub(const nsISomeInterface* aStub, mozilla::MallocSizeOf aMallocSizeOf);
+
+XPCOM_API(nsresult)
+NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                 uint32_t paramCount, nsXPTCVariant* params);
+
+#endif /* xptcall_h___ */
diff --git a/xpcom/reflect/xptcall/xptcprivate.h b/xpcom/reflect/xptcall/xptcprivate.h
new file mode 100644
index 000000000..7805792e7
--- /dev/null
+++ b/xpcom/reflect/xptcall/xptcprivate.h
@@ -0,0 +1,67 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* All the xptcall private declarations - only include locally. */
+
+#ifndef xptcprivate_h___
+#define xptcprivate_h___
+
+#include "xptcall.h"
+#include "nsAutoPtr.h"
+#include "mozilla/Attributes.h"
+
+class xptiInterfaceEntry;
+
+#if !defined(__ia64) || (!defined(__hpux) && !defined(__linux__) && !defined(__FreeBSD__))
+#define STUB_ENTRY(n) NS_IMETHOD Stub##n() = 0;
+#else
+#define STUB_ENTRY(n) NS_IMETHOD Stub##n(uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t) = 0;
+#endif
+
+#define SENTINEL_ENTRY(n) NS_IMETHOD Sentinel##n() = 0;
+
+class nsIXPTCStubBase : public nsISupports
+{
+public:
+#include "xptcstubsdef.inc"
+};
+
+#undef STUB_ENTRY
+#undef SENTINEL_ENTRY
+
+#if !defined(__ia64) || (!defined(__hpux) && !defined(__linux__) && !defined(__FreeBSD__))
+#define STUB_ENTRY(n) NS_IMETHOD Stub##n() override;
+#else
+#define STUB_ENTRY(n) NS_IMETHOD Stub##n(uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t) override;
+#endif
+
+#define SENTINEL_ENTRY(n) NS_IMETHOD Sentinel##n() override;
+
+class nsXPTCStubBase final : public nsIXPTCStubBase
+{
+public:
+    NS_DECL_ISUPPORTS_INHERITED
+
+#include "xptcstubsdef.inc"
+
+    nsXPTCStubBase(nsIXPTCProxy* aOuter, xptiInterfaceEntry *aEntry)
+        : mOuter(aOuter), mEntry(aEntry) { MOZ_COUNT_CTOR(nsXPTCStubBase); }
+
+    nsIXPTCProxy*          mOuter;
+    xptiInterfaceEntry*    mEntry;
+
+    ~nsXPTCStubBase() { MOZ_COUNT_DTOR(nsXPTCStubBase); }
+};
+
+#undef STUB_ENTRY
+#undef SENTINEL_ENTRY
+
+#if defined(__clang__) || defined(__GNUC__)
+#define ATTRIBUTE_USED __attribute__ ((__used__))
+#else
+#define ATTRIBUTE_USED
+#endif
+
+#endif /* xptcprivate_h___ */
diff --git a/xpcom/reflect/xptcall/xptcstubsdecl.inc b/xpcom/reflect/xptcall/xptcstubsdecl.inc
new file mode 100644
index 000000000..91d35fe32
--- /dev/null
+++ b/xpcom/reflect/xptcall/xptcstubsdecl.inc
@@ -0,0 +1,761 @@
+/* generated file - DO NOT EDIT */
+
+/* includes 247 stub entries, and 5 sentinel entries */
+
+/*
+*  declarations of normal stubs...
+*  0 is QueryInterface
+*  1 is AddRef
+*  2 is Release
+*/
+#if !defined(__ia64) || (!defined(__hpux) && !defined(__linux__) && !defined(__FreeBSD__))
+NS_IMETHOD Stub3();
+NS_IMETHOD Stub4();
+NS_IMETHOD Stub5();
+NS_IMETHOD Stub6();
+NS_IMETHOD Stub7();
+NS_IMETHOD Stub8();
+NS_IMETHOD Stub9();
+NS_IMETHOD Stub10();
+NS_IMETHOD Stub11();
+NS_IMETHOD Stub12();
+NS_IMETHOD Stub13();
+NS_IMETHOD Stub14();
+NS_IMETHOD Stub15();
+NS_IMETHOD Stub16();
+NS_IMETHOD Stub17();
+NS_IMETHOD Stub18();
+NS_IMETHOD Stub19();
+NS_IMETHOD Stub20();
+NS_IMETHOD Stub21();
+NS_IMETHOD Stub22();
+NS_IMETHOD Stub23();
+NS_IMETHOD Stub24();
+NS_IMETHOD Stub25();
+NS_IMETHOD Stub26();
+NS_IMETHOD Stub27();
+NS_IMETHOD Stub28();
+NS_IMETHOD Stub29();
+NS_IMETHOD Stub30();
+NS_IMETHOD Stub31();
+NS_IMETHOD Stub32();
+NS_IMETHOD Stub33();
+NS_IMETHOD Stub34();
+NS_IMETHOD Stub35();
+NS_IMETHOD Stub36();
+NS_IMETHOD Stub37();
+NS_IMETHOD Stub38();
+NS_IMETHOD Stub39();
+NS_IMETHOD Stub40();
+NS_IMETHOD Stub41();
+NS_IMETHOD Stub42();
+NS_IMETHOD Stub43();
+NS_IMETHOD Stub44();
+NS_IMETHOD Stub45();
+NS_IMETHOD Stub46();
+NS_IMETHOD Stub47();
+NS_IMETHOD Stub48();
+NS_IMETHOD Stub49();
+NS_IMETHOD Stub50();
+NS_IMETHOD Stub51();
+NS_IMETHOD Stub52();
+NS_IMETHOD Stub53();
+NS_IMETHOD Stub54();
+NS_IMETHOD Stub55();
+NS_IMETHOD Stub56();
+NS_IMETHOD Stub57();
+NS_IMETHOD Stub58();
+NS_IMETHOD Stub59();
+NS_IMETHOD Stub60();
+NS_IMETHOD Stub61();
+NS_IMETHOD Stub62();
+NS_IMETHOD Stub63();
+NS_IMETHOD Stub64();
+NS_IMETHOD Stub65();
+NS_IMETHOD Stub66();
+NS_IMETHOD Stub67();
+NS_IMETHOD Stub68();
+NS_IMETHOD Stub69();
+NS_IMETHOD Stub70();
+NS_IMETHOD Stub71();
+NS_IMETHOD Stub72();
+NS_IMETHOD Stub73();
+NS_IMETHOD Stub74();
+NS_IMETHOD Stub75();
+NS_IMETHOD Stub76();
+NS_IMETHOD Stub77();
+NS_IMETHOD Stub78();
+NS_IMETHOD Stub79();
+NS_IMETHOD Stub80();
+NS_IMETHOD Stub81();
+NS_IMETHOD Stub82();
+NS_IMETHOD Stub83();
+NS_IMETHOD Stub84();
+NS_IMETHOD Stub85();
+NS_IMETHOD Stub86();
+NS_IMETHOD Stub87();
+NS_IMETHOD Stub88();
+NS_IMETHOD Stub89();
+NS_IMETHOD Stub90();
+NS_IMETHOD Stub91();
+NS_IMETHOD Stub92();
+NS_IMETHOD Stub93();
+NS_IMETHOD Stub94();
+NS_IMETHOD Stub95();
+NS_IMETHOD Stub96();
+NS_IMETHOD Stub97();
+NS_IMETHOD Stub98();
+NS_IMETHOD Stub99();
+NS_IMETHOD Stub100();
+NS_IMETHOD Stub101();
+NS_IMETHOD Stub102();
+NS_IMETHOD Stub103();
+NS_IMETHOD Stub104();
+NS_IMETHOD Stub105();
+NS_IMETHOD Stub106();
+NS_IMETHOD Stub107();
+NS_IMETHOD Stub108();
+NS_IMETHOD Stub109();
+NS_IMETHOD Stub110();
+NS_IMETHOD Stub111();
+NS_IMETHOD Stub112();
+NS_IMETHOD Stub113();
+NS_IMETHOD Stub114();
+NS_IMETHOD Stub115();
+NS_IMETHOD Stub116();
+NS_IMETHOD Stub117();
+NS_IMETHOD Stub118();
+NS_IMETHOD Stub119();
+NS_IMETHOD Stub120();
+NS_IMETHOD Stub121();
+NS_IMETHOD Stub122();
+NS_IMETHOD Stub123();
+NS_IMETHOD Stub124();
+NS_IMETHOD Stub125();
+NS_IMETHOD Stub126();
+NS_IMETHOD Stub127();
+NS_IMETHOD Stub128();
+NS_IMETHOD Stub129();
+NS_IMETHOD Stub130();
+NS_IMETHOD Stub131();
+NS_IMETHOD Stub132();
+NS_IMETHOD Stub133();
+NS_IMETHOD Stub134();
+NS_IMETHOD Stub135();
+NS_IMETHOD Stub136();
+NS_IMETHOD Stub137();
+NS_IMETHOD Stub138();
+NS_IMETHOD Stub139();
+NS_IMETHOD Stub140();
+NS_IMETHOD Stub141();
+NS_IMETHOD Stub142();
+NS_IMETHOD Stub143();
+NS_IMETHOD Stub144();
+NS_IMETHOD Stub145();
+NS_IMETHOD Stub146();
+NS_IMETHOD Stub147();
+NS_IMETHOD Stub148();
+NS_IMETHOD Stub149();
+NS_IMETHOD Stub150();
+NS_IMETHOD Stub151();
+NS_IMETHOD Stub152();
+NS_IMETHOD Stub153();
+NS_IMETHOD Stub154();
+NS_IMETHOD Stub155();
+NS_IMETHOD Stub156();
+NS_IMETHOD Stub157();
+NS_IMETHOD Stub158();
+NS_IMETHOD Stub159();
+NS_IMETHOD Stub160();
+NS_IMETHOD Stub161();
+NS_IMETHOD Stub162();
+NS_IMETHOD Stub163();
+NS_IMETHOD Stub164();
+NS_IMETHOD Stub165();
+NS_IMETHOD Stub166();
+NS_IMETHOD Stub167();
+NS_IMETHOD Stub168();
+NS_IMETHOD Stub169();
+NS_IMETHOD Stub170();
+NS_IMETHOD Stub171();
+NS_IMETHOD Stub172();
+NS_IMETHOD Stub173();
+NS_IMETHOD Stub174();
+NS_IMETHOD Stub175();
+NS_IMETHOD Stub176();
+NS_IMETHOD Stub177();
+NS_IMETHOD Stub178();
+NS_IMETHOD Stub179();
+NS_IMETHOD Stub180();
+NS_IMETHOD Stub181();
+NS_IMETHOD Stub182();
+NS_IMETHOD Stub183();
+NS_IMETHOD Stub184();
+NS_IMETHOD Stub185();
+NS_IMETHOD Stub186();
+NS_IMETHOD Stub187();
+NS_IMETHOD Stub188();
+NS_IMETHOD Stub189();
+NS_IMETHOD Stub190();
+NS_IMETHOD Stub191();
+NS_IMETHOD Stub192();
+NS_IMETHOD Stub193();
+NS_IMETHOD Stub194();
+NS_IMETHOD Stub195();
+NS_IMETHOD Stub196();
+NS_IMETHOD Stub197();
+NS_IMETHOD Stub198();
+NS_IMETHOD Stub199();
+NS_IMETHOD Stub200();
+NS_IMETHOD Stub201();
+NS_IMETHOD Stub202();
+NS_IMETHOD Stub203();
+NS_IMETHOD Stub204();
+NS_IMETHOD Stub205();
+NS_IMETHOD Stub206();
+NS_IMETHOD Stub207();
+NS_IMETHOD Stub208();
+NS_IMETHOD Stub209();
+NS_IMETHOD Stub210();
+NS_IMETHOD Stub211();
+NS_IMETHOD Stub212();
+NS_IMETHOD Stub213();
+NS_IMETHOD Stub214();
+NS_IMETHOD Stub215();
+NS_IMETHOD Stub216();
+NS_IMETHOD Stub217();
+NS_IMETHOD Stub218();
+NS_IMETHOD Stub219();
+NS_IMETHOD Stub220();
+NS_IMETHOD Stub221();
+NS_IMETHOD Stub222();
+NS_IMETHOD Stub223();
+NS_IMETHOD Stub224();
+NS_IMETHOD Stub225();
+NS_IMETHOD Stub226();
+NS_IMETHOD Stub227();
+NS_IMETHOD Stub228();
+NS_IMETHOD Stub229();
+NS_IMETHOD Stub230();
+NS_IMETHOD Stub231();
+NS_IMETHOD Stub232();
+NS_IMETHOD Stub233();
+NS_IMETHOD Stub234();
+NS_IMETHOD Stub235();
+NS_IMETHOD Stub236();
+NS_IMETHOD Stub237();
+NS_IMETHOD Stub238();
+NS_IMETHOD Stub239();
+NS_IMETHOD Stub240();
+NS_IMETHOD Stub241();
+NS_IMETHOD Stub242();
+NS_IMETHOD Stub243();
+NS_IMETHOD Stub244();
+NS_IMETHOD Stub245();
+NS_IMETHOD Stub246();
+NS_IMETHOD Stub247();
+NS_IMETHOD Stub248();
+NS_IMETHOD Stub249();
+#else
+NS_IMETHOD Stub3(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub4(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub5(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub6(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub7(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub8(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub9(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub10(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub11(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub12(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub13(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub14(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub15(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub16(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub17(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub18(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub19(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub20(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub21(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub22(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub23(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub24(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub25(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub26(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub27(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub28(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub29(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub30(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub31(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub32(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub33(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub34(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub35(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub36(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub37(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub38(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub39(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub40(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub41(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub42(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub43(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub44(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub45(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub46(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub47(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub48(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub49(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub50(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub51(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub52(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub53(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub54(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub55(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub56(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub57(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub58(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub59(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub60(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub61(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub62(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub63(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub64(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub65(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub66(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub67(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub68(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub69(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub70(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub71(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub72(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub73(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub74(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub75(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub76(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub77(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub78(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub79(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub80(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub81(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub82(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub83(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub84(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub85(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub86(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub87(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub88(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub89(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub90(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub91(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub92(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub93(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub94(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub95(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub96(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub97(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub98(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub99(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub100(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub101(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub102(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub103(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub104(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub105(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub106(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub107(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub108(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub109(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub110(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub111(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub112(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub113(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub114(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub115(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub116(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub117(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub118(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub119(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub120(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub121(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub122(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub123(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub124(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub125(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub126(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub127(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub128(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub129(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub130(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub131(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub132(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub133(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub134(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub135(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub136(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub137(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub138(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub139(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub140(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub141(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub142(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub143(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub144(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub145(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub146(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub147(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub148(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub149(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub150(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub151(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub152(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub153(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub154(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub155(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub156(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub157(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub158(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub159(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub160(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub161(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub162(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub163(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub164(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub165(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub166(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub167(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub168(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub169(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub170(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub171(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub172(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub173(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub174(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub175(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub176(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub177(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub178(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub179(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub180(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub181(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub182(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub183(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub184(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub185(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub186(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub187(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub188(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub189(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub190(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub191(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub192(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub193(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub194(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub195(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub196(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub197(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub198(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub199(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub200(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub201(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub202(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub203(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub204(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub205(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub206(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub207(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub208(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub209(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub210(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub211(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub212(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub213(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub214(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub215(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub216(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub217(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub218(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub219(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub220(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub221(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub222(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub223(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub224(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub225(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub226(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub227(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub228(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub229(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub230(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub231(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub232(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub233(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub234(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub235(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub236(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub237(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub238(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub239(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub240(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub241(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub242(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub243(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub244(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub245(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub246(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub247(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub248(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+NS_IMETHOD Stub249(uint64_t,uint64_t,
+ uint64_t,uint64_t,uint64_t,uint64_t,uint64_t,uint64_t);
+#endif
+
+/* declarations of sentinel stubs */
+NS_IMETHOD Sentinel0();
+NS_IMETHOD Sentinel1();
+NS_IMETHOD Sentinel2();
+NS_IMETHOD Sentinel3();
+NS_IMETHOD Sentinel4();
diff --git a/xpcom/reflect/xptcall/xptcstubsdef.inc b/xpcom/reflect/xptcall/xptcstubsdef.inc
new file mode 100644
index 000000000..2df455406
--- /dev/null
+++ b/xpcom/reflect/xptcall/xptcstubsdef.inc
@@ -0,0 +1,252 @@
+STUB_ENTRY(3)
+STUB_ENTRY(4)
+STUB_ENTRY(5)
+STUB_ENTRY(6)
+STUB_ENTRY(7)
+STUB_ENTRY(8)
+STUB_ENTRY(9)
+STUB_ENTRY(10)
+STUB_ENTRY(11)
+STUB_ENTRY(12)
+STUB_ENTRY(13)
+STUB_ENTRY(14)
+STUB_ENTRY(15)
+STUB_ENTRY(16)
+STUB_ENTRY(17)
+STUB_ENTRY(18)
+STUB_ENTRY(19)
+STUB_ENTRY(20)
+STUB_ENTRY(21)
+STUB_ENTRY(22)
+STUB_ENTRY(23)
+STUB_ENTRY(24)
+STUB_ENTRY(25)
+STUB_ENTRY(26)
+STUB_ENTRY(27)
+STUB_ENTRY(28)
+STUB_ENTRY(29)
+STUB_ENTRY(30)
+STUB_ENTRY(31)
+STUB_ENTRY(32)
+STUB_ENTRY(33)
+STUB_ENTRY(34)
+STUB_ENTRY(35)
+STUB_ENTRY(36)
+STUB_ENTRY(37)
+STUB_ENTRY(38)
+STUB_ENTRY(39)
+STUB_ENTRY(40)
+STUB_ENTRY(41)
+STUB_ENTRY(42)
+STUB_ENTRY(43)
+STUB_ENTRY(44)
+STUB_ENTRY(45)
+STUB_ENTRY(46)
+STUB_ENTRY(47)
+STUB_ENTRY(48)
+STUB_ENTRY(49)
+STUB_ENTRY(50)
+STUB_ENTRY(51)
+STUB_ENTRY(52)
+STUB_ENTRY(53)
+STUB_ENTRY(54)
+STUB_ENTRY(55)
+STUB_ENTRY(56)
+STUB_ENTRY(57)
+STUB_ENTRY(58)
+STUB_ENTRY(59)
+STUB_ENTRY(60)
+STUB_ENTRY(61)
+STUB_ENTRY(62)
+STUB_ENTRY(63)
+STUB_ENTRY(64)
+STUB_ENTRY(65)
+STUB_ENTRY(66)
+STUB_ENTRY(67)
+STUB_ENTRY(68)
+STUB_ENTRY(69)
+STUB_ENTRY(70)
+STUB_ENTRY(71)
+STUB_ENTRY(72)
+STUB_ENTRY(73)
+STUB_ENTRY(74)
+STUB_ENTRY(75)
+STUB_ENTRY(76)
+STUB_ENTRY(77)
+STUB_ENTRY(78)
+STUB_ENTRY(79)
+STUB_ENTRY(80)
+STUB_ENTRY(81)
+STUB_ENTRY(82)
+STUB_ENTRY(83)
+STUB_ENTRY(84)
+STUB_ENTRY(85)
+STUB_ENTRY(86)
+STUB_ENTRY(87)
+STUB_ENTRY(88)
+STUB_ENTRY(89)
+STUB_ENTRY(90)
+STUB_ENTRY(91)
+STUB_ENTRY(92)
+STUB_ENTRY(93)
+STUB_ENTRY(94)
+STUB_ENTRY(95)
+STUB_ENTRY(96)
+STUB_ENTRY(97)
+STUB_ENTRY(98)
+STUB_ENTRY(99)
+STUB_ENTRY(100)
+STUB_ENTRY(101)
+STUB_ENTRY(102)
+STUB_ENTRY(103)
+STUB_ENTRY(104)
+STUB_ENTRY(105)
+STUB_ENTRY(106)
+STUB_ENTRY(107)
+STUB_ENTRY(108)
+STUB_ENTRY(109)
+STUB_ENTRY(110)
+STUB_ENTRY(111)
+STUB_ENTRY(112)
+STUB_ENTRY(113)
+STUB_ENTRY(114)
+STUB_ENTRY(115)
+STUB_ENTRY(116)
+STUB_ENTRY(117)
+STUB_ENTRY(118)
+STUB_ENTRY(119)
+STUB_ENTRY(120)
+STUB_ENTRY(121)
+STUB_ENTRY(122)
+STUB_ENTRY(123)
+STUB_ENTRY(124)
+STUB_ENTRY(125)
+STUB_ENTRY(126)
+STUB_ENTRY(127)
+STUB_ENTRY(128)
+STUB_ENTRY(129)
+STUB_ENTRY(130)
+STUB_ENTRY(131)
+STUB_ENTRY(132)
+STUB_ENTRY(133)
+STUB_ENTRY(134)
+STUB_ENTRY(135)
+STUB_ENTRY(136)
+STUB_ENTRY(137)
+STUB_ENTRY(138)
+STUB_ENTRY(139)
+STUB_ENTRY(140)
+STUB_ENTRY(141)
+STUB_ENTRY(142)
+STUB_ENTRY(143)
+STUB_ENTRY(144)
+STUB_ENTRY(145)
+STUB_ENTRY(146)
+STUB_ENTRY(147)
+STUB_ENTRY(148)
+STUB_ENTRY(149)
+STUB_ENTRY(150)
+STUB_ENTRY(151)
+STUB_ENTRY(152)
+STUB_ENTRY(153)
+STUB_ENTRY(154)
+STUB_ENTRY(155)
+STUB_ENTRY(156)
+STUB_ENTRY(157)
+STUB_ENTRY(158)
+STUB_ENTRY(159)
+STUB_ENTRY(160)
+STUB_ENTRY(161)
+STUB_ENTRY(162)
+STUB_ENTRY(163)
+STUB_ENTRY(164)
+STUB_ENTRY(165)
+STUB_ENTRY(166)
+STUB_ENTRY(167)
+STUB_ENTRY(168)
+STUB_ENTRY(169)
+STUB_ENTRY(170)
+STUB_ENTRY(171)
+STUB_ENTRY(172)
+STUB_ENTRY(173)
+STUB_ENTRY(174)
+STUB_ENTRY(175)
+STUB_ENTRY(176)
+STUB_ENTRY(177)
+STUB_ENTRY(178)
+STUB_ENTRY(179)
+STUB_ENTRY(180)
+STUB_ENTRY(181)
+STUB_ENTRY(182)
+STUB_ENTRY(183)
+STUB_ENTRY(184)
+STUB_ENTRY(185)
+STUB_ENTRY(186)
+STUB_ENTRY(187)
+STUB_ENTRY(188)
+STUB_ENTRY(189)
+STUB_ENTRY(190)
+STUB_ENTRY(191)
+STUB_ENTRY(192)
+STUB_ENTRY(193)
+STUB_ENTRY(194)
+STUB_ENTRY(195)
+STUB_ENTRY(196)
+STUB_ENTRY(197)
+STUB_ENTRY(198)
+STUB_ENTRY(199)
+STUB_ENTRY(200)
+STUB_ENTRY(201)
+STUB_ENTRY(202)
+STUB_ENTRY(203)
+STUB_ENTRY(204)
+STUB_ENTRY(205)
+STUB_ENTRY(206)
+STUB_ENTRY(207)
+STUB_ENTRY(208)
+STUB_ENTRY(209)
+STUB_ENTRY(210)
+STUB_ENTRY(211)
+STUB_ENTRY(212)
+STUB_ENTRY(213)
+STUB_ENTRY(214)
+STUB_ENTRY(215)
+STUB_ENTRY(216)
+STUB_ENTRY(217)
+STUB_ENTRY(218)
+STUB_ENTRY(219)
+STUB_ENTRY(220)
+STUB_ENTRY(221)
+STUB_ENTRY(222)
+STUB_ENTRY(223)
+STUB_ENTRY(224)
+STUB_ENTRY(225)
+STUB_ENTRY(226)
+STUB_ENTRY(227)
+STUB_ENTRY(228)
+STUB_ENTRY(229)
+STUB_ENTRY(230)
+STUB_ENTRY(231)
+STUB_ENTRY(232)
+STUB_ENTRY(233)
+STUB_ENTRY(234)
+STUB_ENTRY(235)
+STUB_ENTRY(236)
+STUB_ENTRY(237)
+STUB_ENTRY(238)
+STUB_ENTRY(239)
+STUB_ENTRY(240)
+STUB_ENTRY(241)
+STUB_ENTRY(242)
+STUB_ENTRY(243)
+STUB_ENTRY(244)
+STUB_ENTRY(245)
+STUB_ENTRY(246)
+STUB_ENTRY(247)
+STUB_ENTRY(248)
+STUB_ENTRY(249)
+SENTINEL_ENTRY(0)
+SENTINEL_ENTRY(1)
+SENTINEL_ENTRY(2)
+SENTINEL_ENTRY(3)
+SENTINEL_ENTRY(4)
diff --git a/xpcom/reflect/xptinfo/ShimInterfaceInfo.cpp b/xpcom/reflect/xptinfo/ShimInterfaceInfo.cpp
new file mode 100644
index 000000000..14e719f6c
--- /dev/null
+++ b/xpcom/reflect/xptinfo/ShimInterfaceInfo.cpp
@@ -0,0 +1,700 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sw=4 et tw=78:
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ShimInterfaceInfo.h"
+
+#include "nsIBrowserBoxObject.h"
+#include "nsIContainerBoxObject.h"
+#include "nsIDOMAnimationEvent.h"
+#include "nsIDOMAttr.h"
+#include "nsIDOMBeforeUnloadEvent.h"
+#include "nsIDOMCanvasRenderingContext2D.h"
+#include "nsIDOMCDATASection.h"
+#include "nsIDOMCharacterData.h"
+#include "nsIDOMClientRect.h"
+#include "nsIDOMClientRectList.h"
+#include "nsIDOMClipboardEvent.h"
+#include "nsIDOMCommandEvent.h"
+#include "nsIDOMComment.h"
+#include "nsIDOMCSSPrimitiveValue.h"
+#include "nsIDOMCSSStyleDeclaration.h"
+#include "nsIDOMCSSStyleSheet.h"
+#include "nsIDOMCSSValue.h"
+#include "nsIDOMCSSValueList.h"
+#include "nsIDOMCustomEvent.h"
+#include "nsIDOMDataContainerEvent.h"
+#ifdef MOZ_WEBRTC
+#include "nsIDOMDataChannel.h"
+#endif
+#include "nsIDOMDataTransfer.h"
+#include "nsIDOMDOMCursor.h"
+#include "nsIDOMDOMException.h"
+#include "nsIDOMDOMRequest.h"
+#include "nsIDOMDocument.h"
+#include "nsIDOMDocumentFragment.h"
+#include "nsIDOMDocumentType.h"
+#include "nsIDOMDocumentXBL.h"
+#include "nsIDOMDragEvent.h"
+#include "nsIDOMElement.h"
+#include "nsIDOMEvent.h"
+#include "nsIDOMEventTarget.h"
+#include "nsIDOMFileList.h"
+#include "nsIDOMFocusEvent.h"
+#include "nsIDOMFormData.h"
+#include "nsIDOMGeoPositionError.h"
+#include "nsIDOMHistory.h"
+#include "nsIDOMHTMLAnchorElement.h"
+#include "nsIDOMHTMLAppletElement.h"
+#include "nsIDOMHTMLAreaElement.h"
+#include "nsIDOMHTMLBaseElement.h"
+#include "nsIDOMHTMLBodyElement.h"
+#include "nsIDOMHTMLButtonElement.h"
+#include "nsIDOMHTMLCanvasElement.h"
+#include "nsIDOMHTMLCollection.h"
+#include "nsIDOMHTMLDirectoryElement.h"
+#include "nsIDOMHTMLDocument.h"
+#include "nsIDOMHTMLElement.h"
+#include "nsIDOMHTMLEmbedElement.h"
+#include "nsIDOMHTMLFieldSetElement.h"
+#include "nsIDOMHTMLFormElement.h"
+#include "nsIDOMHTMLFrameElement.h"
+#include "nsIDOMHTMLFrameSetElement.h"
+#include "nsIDOMHTMLHRElement.h"
+#include "nsIDOMHTMLHeadElement.h"
+#include "nsIDOMHTMLHtmlElement.h"
+#include "nsIDOMHTMLIFrameElement.h"
+#include "nsIDOMHTMLImageElement.h"
+#include "nsIDOMHTMLInputElement.h"
+#include "nsIDOMHTMLLIElement.h"
+#include "nsIDOMHTMLLabelElement.h"
+#include "nsIDOMHTMLLinkElement.h"
+#include "nsIDOMHTMLMapElement.h"
+#include "nsIDOMHTMLMediaElement.h"
+#include "nsIDOMHTMLMenuElement.h"
+#include "nsIDOMHTMLMenuItemElement.h"
+#include "nsIDOMHTMLMetaElement.h"
+#include "nsIDOMHTMLOListElement.h"
+#include "nsIDOMHTMLObjectElement.h"
+#include "nsIDOMHTMLOptGroupElement.h"
+#include "nsIDOMHTMLOptionElement.h"
+#include "nsIDOMHTMLOptionsCollection.h"
+#include "nsIDOMHTMLParagraphElement.h"
+#include "nsIDOMHTMLPreElement.h"
+#include "nsIDOMHTMLQuoteElement.h"
+#include "nsIDOMHTMLScriptElement.h"
+#include "nsIDOMHTMLSelectElement.h"
+#include "nsIDOMHTMLSourceElement.h"
+#include "nsIDOMHTMLStyleElement.h"
+#include "nsIDOMHTMLTableCellElement.h"
+#include "nsIDOMHTMLTextAreaElement.h"
+#include "nsIDOMHTMLUListElement.h"
+#include "nsIDOMKeyEvent.h"
+#include "nsIDOMMediaList.h"
+#include "nsIDOMMouseEvent.h"
+#include "nsIDOMMouseScrollEvent.h"
+#include "nsIDOMMutationEvent.h"
+#include "nsIDOMMozNamedAttrMap.h"
+#include "nsIDOMNode.h"
+#include "nsIDOMNodeIterator.h"
+#include "nsIDOMNotifyPaintEvent.h"
+#include "nsIDOMNSEvent.h"
+#include "nsIDOMOfflineResourceList.h"
+#include "nsIDOMPaintRequest.h"
+#include "nsIDOMParser.h"
+#include "nsIDOMProcessingInstruction.h"
+#include "nsIDOMRange.h"
+#include "nsIDOMRect.h"
+#include "nsIDOMScreen.h"
+#include "nsIDOMScrollAreaEvent.h"
+#include "nsIDOMSerializer.h"
+#include "nsIDOMSimpleGestureEvent.h"
+#include "nsIDOMStyleSheet.h"
+#include "nsIDOMStyleSheetList.h"
+#include "nsIDOMSVGElement.h"
+#include "nsIDOMSVGLength.h"
+#include "nsIDOMText.h"
+#include "nsIDOMTimeEvent.h"
+#include "nsIDOMTimeRanges.h"
+#include "nsIDOMTransitionEvent.h"
+#include "nsIDOMTreeWalker.h"
+#include "nsIDOMUIEvent.h"
+#include "nsIDOMValidityState.h"
+#include "nsIDOMWheelEvent.h"
+#include "nsIDOMXMLDocument.h"
+#include "nsIDOMXPathEvaluator.h"
+#include "nsIDOMXPathResult.h"
+#include "nsIDOMXULCommandEvent.h"
+#include "nsIDOMXULDocument.h"
+#include "nsIDOMXULElement.h"
+#include "nsIListBoxObject.h"
+#include "nsIMenuBoxObject.h"
+#include "nsIScrollBoxObject.h"
+#include "nsISelection.h"
+#include "nsITreeBoxObject.h"
+#include "nsIXMLHttpRequest.h"
+
+#include "mozilla/dom/AnimationEventBinding.h"
+#include "mozilla/dom/AttrBinding.h"
+#include "mozilla/dom/BeforeUnloadEventBinding.h"
+#include "mozilla/dom/CanvasRenderingContext2DBinding.h"
+#include "mozilla/dom/CDATASectionBinding.h"
+#include "mozilla/dom/CharacterDataBinding.h"
+#include "mozilla/dom/DOMRectBinding.h"
+#include "mozilla/dom/DOMRectListBinding.h"
+#include "mozilla/dom/ClipboardEventBinding.h"
+#include "mozilla/dom/CommandEventBinding.h"
+#include "mozilla/dom/CommentBinding.h"
+#include "mozilla/dom/ContainerBoxObjectBinding.h"
+#include "mozilla/dom/CSSPrimitiveValueBinding.h"
+#include "mozilla/dom/CSSStyleDeclarationBinding.h"
+#include "mozilla/dom/CSSStyleSheetBinding.h"
+#include "mozilla/dom/CSSValueBinding.h"
+#include "mozilla/dom/CSSValueListBinding.h"
+#include "mozilla/dom/CustomEventBinding.h"
+#ifdef MOZ_WEBRTC
+#include "mozilla/dom/DataChannelBinding.h"
+#endif
+#include "mozilla/dom/DataContainerEventBinding.h"
+#include "mozilla/dom/DataTransferBinding.h"
+#include "mozilla/dom/DOMCursorBinding.h"
+#include "mozilla/dom/DOMExceptionBinding.h"
+#include "mozilla/dom/DOMParserBinding.h"
+#include "mozilla/dom/DOMRequestBinding.h"
+#include "mozilla/dom/DocumentBinding.h"
+#include "mozilla/dom/DocumentFragmentBinding.h"
+#include "mozilla/dom/DocumentTypeBinding.h"
+#include "mozilla/dom/DocumentBinding.h"
+#include "mozilla/dom/DragEventBinding.h"
+#include "mozilla/dom/ElementBinding.h"
+#include "mozilla/dom/EventBinding.h"
+#include "mozilla/dom/EventTargetBinding.h"
+#include "mozilla/dom/FileListBinding.h"
+#include "mozilla/dom/FocusEventBinding.h"
+#include "mozilla/dom/FormDataBinding.h"
+#include "mozilla/dom/HistoryBinding.h"
+#include "mozilla/dom/HTMLAnchorElementBinding.h"
+#include "mozilla/dom/HTMLAppletElementBinding.h"
+#include "mozilla/dom/HTMLAreaElementBinding.h"
+#include "mozilla/dom/HTMLBaseElementBinding.h"
+#include "mozilla/dom/HTMLBodyElementBinding.h"
+#include "mozilla/dom/HTMLButtonElementBinding.h"
+#include "mozilla/dom/HTMLCanvasElementBinding.h"
+#include "mozilla/dom/HTMLCollectionBinding.h"
+#include "mozilla/dom/HTMLDirectoryElementBinding.h"
+#include "mozilla/dom/HTMLDocumentBinding.h"
+#include "mozilla/dom/HTMLElementBinding.h"
+#include "mozilla/dom/HTMLEmbedElementBinding.h"
+#include "mozilla/dom/HTMLFieldSetElementBinding.h"
+#include "mozilla/dom/HTMLFormElementBinding.h"
+#include "mozilla/dom/HTMLFrameElementBinding.h"
+#include "mozilla/dom/HTMLFrameSetElementBinding.h"
+#include "mozilla/dom/HTMLHRElementBinding.h"
+#include "mozilla/dom/HTMLHeadElementBinding.h"
+#include "mozilla/dom/HTMLHtmlElementBinding.h"
+#include "mozilla/dom/HTMLIFrameElementBinding.h"
+#include "mozilla/dom/HTMLImageElementBinding.h"
+#include "mozilla/dom/HTMLInputElementBinding.h"
+#include "mozilla/dom/HTMLLIElementBinding.h"
+#include "mozilla/dom/HTMLLabelElementBinding.h"
+#include "mozilla/dom/HTMLLinkElementBinding.h"
+#include "mozilla/dom/HTMLMapElementBinding.h"
+#include "mozilla/dom/HTMLMediaElementBinding.h"
+#include "mozilla/dom/HTMLMenuElementBinding.h"
+#include "mozilla/dom/HTMLMenuItemElementBinding.h"
+#include "mozilla/dom/HTMLMetaElementBinding.h"
+#include "mozilla/dom/HTMLOListElementBinding.h"
+#include "mozilla/dom/HTMLObjectElementBinding.h"
+#include "mozilla/dom/HTMLOptGroupElementBinding.h"
+#include "mozilla/dom/HTMLOptionElementBinding.h"
+#include "mozilla/dom/HTMLOptionsCollectionBinding.h"
+#include "mozilla/dom/HTMLParagraphElementBinding.h"
+#include "mozilla/dom/HTMLPreElementBinding.h"
+#include "mozilla/dom/HTMLQuoteElementBinding.h"
+#include "mozilla/dom/HTMLScriptElementBinding.h"
+#include "mozilla/dom/HTMLSelectElementBinding.h"
+#include "mozilla/dom/HTMLSourceElementBinding.h"
+#include "mozilla/dom/HTMLStyleElementBinding.h"
+#include "mozilla/dom/HTMLTableCellElementBinding.h"
+#include "mozilla/dom/HTMLTextAreaElementBinding.h"
+#include "mozilla/dom/HTMLUListElementBinding.h"
+#include "mozilla/dom/KeyEventBinding.h"
+#include "mozilla/dom/ListBoxObjectBinding.h"
+#include "mozilla/dom/MediaListBinding.h"
+#include "mozilla/dom/MessageEventBinding.h"
+#include "mozilla/dom/MenuBoxObjectBinding.h"
+#include "mozilla/dom/MouseEventBinding.h"
+#include "mozilla/dom/MouseScrollEventBinding.h"
+#include "mozilla/dom/MutationEventBinding.h"
+#include "mozilla/dom/NamedNodeMapBinding.h"
+#include "mozilla/dom/NodeIteratorBinding.h"
+#include "mozilla/dom/NodeBinding.h"
+#include "mozilla/dom/NotifyPaintEventBinding.h"
+#include "mozilla/dom/EventBinding.h"
+#include "mozilla/dom/OfflineResourceListBinding.h"
+#include "mozilla/dom/PaintRequestBinding.h"
+#include "mozilla/dom/PositionErrorBinding.h"
+#include "mozilla/dom/ProcessingInstructionBinding.h"
+#include "mozilla/dom/RangeBinding.h"
+#include "mozilla/dom/RectBinding.h"
+#include "mozilla/dom/ScreenBinding.h"
+#include "mozilla/dom/ScrollBoxObjectBinding.h"
+#include "mozilla/dom/SelectionBinding.h"
+#include "mozilla/dom/ScrollAreaEventBinding.h"
+#include "mozilla/dom/SimpleGestureEventBinding.h"
+#include "mozilla/dom/StorageEventBinding.h"
+#include "mozilla/dom/StyleSheetBinding.h"
+#include "mozilla/dom/StyleSheetListBinding.h"
+#include "mozilla/dom/SVGElementBinding.h"
+#include "mozilla/dom/SVGLengthBinding.h"
+#include "mozilla/dom/TextBinding.h"
+#include "mozilla/dom/TimeEventBinding.h"
+#include "mozilla/dom/TimeRangesBinding.h"
+#include "mozilla/dom/TransitionEventBinding.h"
+#include "mozilla/dom/TreeBoxObjectBinding.h"
+#include "mozilla/dom/TreeWalkerBinding.h"
+#include "mozilla/dom/UIEventBinding.h"
+#include "mozilla/dom/ValidityStateBinding.h"
+#include "mozilla/dom/WheelEventBinding.h"
+#include "mozilla/dom/XMLDocumentBinding.h"
+#include "mozilla/dom/XMLHttpRequestEventTargetBinding.h"
+#include "mozilla/dom/XMLHttpRequestUploadBinding.h"
+#include "mozilla/dom/XMLSerializerBinding.h"
+#include "mozilla/dom/XPathEvaluatorBinding.h"
+#include "mozilla/dom/XPathResultBinding.h"
+#include "mozilla/dom/XULCommandEventBinding.h"
+#include "mozilla/dom/XULDocumentBinding.h"
+#include "mozilla/dom/XULElementBinding.h"
+
+using namespace mozilla;
+
+struct ComponentsInterfaceShimEntry {
+  constexpr
+  ComponentsInterfaceShimEntry(const char* aName, const nsIID& aIID,
+                               const dom::NativePropertyHooks* aNativePropHooks)
+    : geckoName(aName), iid(aIID), nativePropHooks(aNativePropHooks) {}
+
+  const char *geckoName;
+  const nsIID& iid;
+  const dom::NativePropertyHooks* nativePropHooks;
+};
+
+#define DEFINE_SHIM_WITH_CUSTOM_INTERFACE(geckoName, domName) \
+  { #geckoName, NS_GET_IID(geckoName), \
+     mozilla::dom::domName ## Binding::sNativePropertyHooks }
+#define DEFINE_SHIM(name) \
+  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIDOM ## name, name)
+
+/**
+ * These shim entries allow us to make old XPIDL interfaces implementing DOM
+ * APIs as non-scriptable in order to save some runtime memory on Firefox OS,
+ * without breaking the entries under Components.interfaces which might both
+ * be used by our code and add-ons.  Specifically, the shim entries provide
+ * the following:
+ *
+ * * Components.interfaces.nsIFoo entries.  These entries basically work
+ *   almost exactly as the usual ones that you would get through the
+ *   XPIDL machinery.  Specifically, they have the right name, they reflect
+ *   the right IID, and they will work properly when passed to QueryInterface.
+ *
+ * * Components.interfaces.nsIFoo.CONSTANT values.  These entries will have
+ *   the right name and the right value for most integer types.  Note that
+ *   support for non-numerical constants is untested and will probably not
+ *   work out of the box.
+ *
+ * FAQ:
+ * * When should I add an entry to the list here?
+ *   Only if you're making an XPIDL interfaces which has a corresponding
+ *   WebIDL interface non-scriptable.
+ * * When should I remove an entry from this list?
+ *   If you are completely removing an XPIDL interface from the code base.  If
+ *   you forget to do so, the compiler will remind you.
+ * * How should I add an entry to the list here?
+ *   First, make sure that the XPIDL interface in question is non-scriptable
+ *   and also has a corresponding WebIDL interface.  Then, add two include
+ *   entries above, one for the XPIDL interface and one for the WebIDL
+ *   interface, and add a shim entry below.  If the name of the XPIDL
+ *   interface only has an "nsIDOM" prefix prepended to the WebIDL name, you
+ *   can use the DEFINE_SHIM macro and pass in the name of the WebIDL
+ *   interface.  Otherwise, use DEFINE_SHIM_WITH_CUSTOM_INTERFACE.
+ */
+
+const ComponentsInterfaceShimEntry kComponentsInterfaceShimMap[] =
+{
+  DEFINE_SHIM(AnimationEvent),
+  DEFINE_SHIM(Attr),
+  DEFINE_SHIM(BeforeUnloadEvent),
+  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIBrowserBoxObject, ContainerBoxObject),
+  DEFINE_SHIM(CanvasRenderingContext2D),
+  DEFINE_SHIM(CDATASection),
+  DEFINE_SHIM(CharacterData),
+  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIDOMClientRect, DOMRectReadOnly),
+  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIDOMClientRectList, DOMRectList),
+  DEFINE_SHIM(ClipboardEvent),
+  DEFINE_SHIM(CommandEvent),
+  DEFINE_SHIM(Comment),
+  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIContainerBoxObject, ContainerBoxObject),
+  DEFINE_SHIM(CSSPrimitiveValue),
+  DEFINE_SHIM(CSSStyleDeclaration),
+  DEFINE_SHIM(CSSStyleSheet),
+  DEFINE_SHIM(CSSValue),
+  DEFINE_SHIM(CSSValueList),
+  DEFINE_SHIM(CustomEvent),
+#ifdef MOZ_WEBRTC
+  DEFINE_SHIM(DataChannel),
+#endif
+  DEFINE_SHIM(DataContainerEvent),
+  DEFINE_SHIM(DataTransfer),
+  DEFINE_SHIM(DOMCursor),
+  DEFINE_SHIM(DOMException),
+  DEFINE_SHIM(DOMRequest),
+  DEFINE_SHIM(Document),
+  DEFINE_SHIM(DocumentFragment),
+  DEFINE_SHIM(DocumentType),
+  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIDOMDocumentXBL, Document),
+  DEFINE_SHIM(DragEvent),
+  DEFINE_SHIM(Element),
+  DEFINE_SHIM(Event),
+  DEFINE_SHIM(EventTarget),
+  DEFINE_SHIM(FileList),
+  DEFINE_SHIM(FocusEvent),
+  DEFINE_SHIM(FormData),
+  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIDOMGeoPositionError, PositionError),
+  DEFINE_SHIM(History),
+  DEFINE_SHIM(HTMLAnchorElement),
+  DEFINE_SHIM(HTMLAppletElement),
+  DEFINE_SHIM(HTMLAreaElement),
+  DEFINE_SHIM(HTMLBaseElement),
+  DEFINE_SHIM(HTMLBodyElement),
+  DEFINE_SHIM(HTMLButtonElement),
+  DEFINE_SHIM(HTMLCanvasElement),
+  DEFINE_SHIM(HTMLCollection),
+  DEFINE_SHIM(HTMLDirectoryElement),
+  DEFINE_SHIM(HTMLDocument),
+  DEFINE_SHIM(HTMLElement),
+  DEFINE_SHIM(HTMLEmbedElement),
+  DEFINE_SHIM(HTMLFieldSetElement),
+  DEFINE_SHIM(HTMLFormElement),
+  DEFINE_SHIM(HTMLFrameElement),
+  DEFINE_SHIM(HTMLFrameSetElement),
+  DEFINE_SHIM(HTMLHRElement),
+  DEFINE_SHIM(HTMLHeadElement),
+  DEFINE_SHIM(HTMLHtmlElement),
+  DEFINE_SHIM(HTMLIFrameElement),
+  DEFINE_SHIM(HTMLImageElement),
+  DEFINE_SHIM(HTMLInputElement),
+  DEFINE_SHIM(HTMLLIElement),
+  DEFINE_SHIM(HTMLLabelElement),
+  DEFINE_SHIM(HTMLLinkElement),
+  DEFINE_SHIM(HTMLMapElement),
+  DEFINE_SHIM(HTMLMediaElement),
+  DEFINE_SHIM(HTMLMenuElement),
+  DEFINE_SHIM(HTMLMenuItemElement),
+  DEFINE_SHIM(HTMLMetaElement),
+  DEFINE_SHIM(HTMLOListElement),
+  DEFINE_SHIM(HTMLObjectElement),
+  DEFINE_SHIM(HTMLOptGroupElement),
+  DEFINE_SHIM(HTMLOptionElement),
+  DEFINE_SHIM(HTMLOptionsCollection),
+  DEFINE_SHIM(HTMLParagraphElement),
+  DEFINE_SHIM(HTMLPreElement),
+  DEFINE_SHIM(HTMLQuoteElement),
+  DEFINE_SHIM(HTMLScriptElement),
+  DEFINE_SHIM(HTMLSelectElement),
+  DEFINE_SHIM(HTMLSourceElement),
+  DEFINE_SHIM(HTMLStyleElement),
+  DEFINE_SHIM(HTMLTableCellElement),
+  DEFINE_SHIM(HTMLTextAreaElement),
+  DEFINE_SHIM(HTMLUListElement),
+  DEFINE_SHIM(KeyEvent),
+  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIListBoxObject, ListBoxObject),
+  DEFINE_SHIM(MediaList),
+  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIMenuBoxObject, MenuBoxObject),
+  DEFINE_SHIM(MouseEvent),
+  DEFINE_SHIM(MouseScrollEvent),
+  DEFINE_SHIM(MutationEvent),
+  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIDOMMozNamedAttrMap, NamedNodeMap),
+  DEFINE_SHIM(NodeIterator),
+  DEFINE_SHIM(Node),
+  DEFINE_SHIM(NotifyPaintEvent),
+  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIDOMNSEvent, Event),
+  DEFINE_SHIM(OfflineResourceList),
+  DEFINE_SHIM(PaintRequest),
+  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIDOMParser, DOMParser),
+  DEFINE_SHIM(ProcessingInstruction),
+  DEFINE_SHIM(Range),
+  DEFINE_SHIM(Rect),
+  DEFINE_SHIM(Screen),
+  DEFINE_SHIM(ScrollAreaEvent),
+  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIScrollBoxObject, ScrollBoxObject),
+  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIDOMSerializer, XMLSerializer),
+  DEFINE_SHIM(SimpleGestureEvent),
+  DEFINE_SHIM(StyleSheet),
+  DEFINE_SHIM(StyleSheetList),
+  DEFINE_SHIM(SVGElement),
+  DEFINE_SHIM(SVGLength),
+  DEFINE_SHIM(Text),
+  DEFINE_SHIM(TimeEvent),
+  DEFINE_SHIM(TimeRanges),
+  DEFINE_SHIM(TransitionEvent),
+  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsITreeBoxObject, TreeBoxObject),
+  DEFINE_SHIM(TreeWalker),
+  DEFINE_SHIM(UIEvent),
+  DEFINE_SHIM(ValidityState),
+  DEFINE_SHIM(WheelEvent),
+  DEFINE_SHIM(XMLDocument),
+  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIXMLHttpRequestEventTarget, XMLHttpRequestEventTarget),
+  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsIXMLHttpRequestUpload, XMLHttpRequestUpload),
+  DEFINE_SHIM(XPathEvaluator),
+  DEFINE_SHIM(XPathResult),
+  DEFINE_SHIM(XULCommandEvent),
+  DEFINE_SHIM(XULDocument),
+  DEFINE_SHIM(XULElement),
+  DEFINE_SHIM_WITH_CUSTOM_INTERFACE(nsISelection, Selection),
+};
+
+#undef DEFINE_SHIM
+#undef DEFINE_SHIM_WITH_CUSTOM_INTERFACE
+
+NS_IMPL_ISUPPORTS(ShimInterfaceInfo, nsISupports, nsIInterfaceInfo)
+
+already_AddRefed<ShimInterfaceInfo>
+ShimInterfaceInfo::MaybeConstruct(const char* aName, JSContext* cx)
+{
+    RefPtr<ShimInterfaceInfo> info;
+    for (uint32_t i = 0; i < ArrayLength(kComponentsInterfaceShimMap); ++i) {
+        if (!strcmp(aName, kComponentsInterfaceShimMap[i].geckoName)) {
+            const ComponentsInterfaceShimEntry& shimEntry =
+                kComponentsInterfaceShimMap[i];
+            info = new ShimInterfaceInfo(shimEntry.iid,
+                                         shimEntry.geckoName,
+                                         shimEntry.nativePropHooks);
+            break;
+        }
+    }
+    return info.forget();
+}
+
+ShimInterfaceInfo::ShimInterfaceInfo(const nsIID& aIID,
+                                     const char* aName,
+                                     const mozilla::dom::NativePropertyHooks* aNativePropHooks)
+    : mIID(aIID)
+    , mName(aName)
+    , mNativePropHooks(aNativePropHooks)
+{
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::GetName(char** aName)
+{
+    *aName = ToNewCString(mName);
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::GetInterfaceIID(nsIID** aIID)
+{
+    *aIID = static_cast<nsIID*> (nsMemory::Clone(&mIID, sizeof(mIID)));
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::IsScriptable(bool* aRetVal)
+{
+    // This class should pretend that the interface is scriptable because
+    // that's what nsJSIID assumes.
+    *aRetVal = true;
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::IsBuiltinClass(bool* aRetVal)
+{
+    *aRetVal = true;
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::IsMainProcessScriptableOnly(bool* aRetVal)
+{
+    *aRetVal = false;
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::GetParent(nsIInterfaceInfo** aParent)
+{
+    *aParent = nullptr;
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::GetMethodCount(uint16_t* aCount)
+{
+    // Pretend we don't have any methods.
+    *aCount = 0;
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::GetConstantCount(uint16_t* aCount)
+{
+    // We assume that we never have interfaces with more than UINT16_MAX
+    // constants defined on them.
+    uint16_t count = 0;
+
+    // NOTE: The structure of this loop must be kept in sync with the loop
+    // in GetConstant.
+    const mozilla::dom::NativePropertyHooks* propHooks = mNativePropHooks;
+    do {
+        const mozilla::dom::NativeProperties* props[] = {
+            propHooks->mNativeProperties.regular,
+            propHooks->mNativeProperties.chromeOnly
+        };
+        for (size_t i = 0; i < ArrayLength(props); ++i) {
+            auto prop = props[i];
+            if (prop && prop->HasConstants()) {
+                for (auto cs = prop->Constants()->specs; cs->name; ++cs) {
+                    // We have found one constant here.  We explicitly do not
+                    // bother calling isEnabled() here because it's OK to define
+                    // potentially extra constants on these shim interfaces.
+                    ++count;
+                }
+            }
+        }
+    } while ((propHooks = propHooks->mProtoHooks));
+    *aCount = count;
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::GetMethodInfo(uint16_t aIndex, const nsXPTMethodInfo** aInfo)
+{
+    MOZ_ASSERT(false, "This should never be called");
+    return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::GetMethodInfoForName(const char* aName, uint16_t* aIndex, const nsXPTMethodInfo** aInfo)
+{
+    MOZ_ASSERT(false, "This should never be called");
+    return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::GetConstant(uint16_t aIndex, JS::MutableHandleValue aConstant,
+                               char** aName)
+{
+    // We assume that we never have interfaces with more than UINT16_MAX
+    // constants defined on them.
+    uint16_t index = 0;
+
+    // NOTE: The structure of this loop must be kept in sync with the loop
+    // in GetConstantCount.
+    const mozilla::dom::NativePropertyHooks* propHooks = mNativePropHooks;
+    do {
+        const mozilla::dom::NativeProperties* props[] = {
+            propHooks->mNativeProperties.regular,
+            propHooks->mNativeProperties.chromeOnly
+        };
+        for (size_t i = 0; i < ArrayLength(props); ++i) {
+            auto prop = props[i];
+            if (prop && prop->HasConstants()) {
+                for (auto cs = prop->Constants()->specs; cs->name; ++cs) {
+                    // We have found one constant here.  We explicitly do not
+                    // bother calling isEnabled() here because it's OK to define
+                    // potentially extra constants on these shim interfaces.
+                    if (index == aIndex) {
+                        aConstant.set(cs->value);
+                        *aName = ToNewCString(nsDependentCString(cs->name));
+                        return NS_OK;
+                    }
+                    ++index;
+                }
+            }
+        }
+    } while ((propHooks = propHooks->mProtoHooks));
+
+    // aIndex was bigger than the number of constants we have.
+    return NS_ERROR_INVALID_ARG;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::GetInfoForParam(uint16_t aIndex, const nsXPTParamInfo* aParam, nsIInterfaceInfo** aRetVal)
+{
+    MOZ_ASSERT(false, "This should never be called");
+    return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::GetIIDForParam(uint16_t aIndex, const nsXPTParamInfo* aParam, nsIID** aRetVal)
+{
+    MOZ_ASSERT(false, "This should never be called");
+    return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::GetTypeForParam(uint16_t aInex, const nsXPTParamInfo* aParam, uint16_t aDimension, nsXPTType* aRetVal)
+{
+    MOZ_ASSERT(false, "This should never be called");
+    return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::GetSizeIsArgNumberForParam(uint16_t aInex, const nsXPTParamInfo* aParam, uint16_t aDimension, uint8_t* aRetVal)
+{
+    MOZ_ASSERT(false, "This should never be called");
+    return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::GetInterfaceIsArgNumberForParam(uint16_t aInex, const nsXPTParamInfo* aParam, uint8_t* aRetVal)
+{
+    MOZ_ASSERT(false, "This should never be called");
+    return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::IsIID(const nsIID* aIID, bool* aRetVal)
+{
+    *aRetVal = mIID.Equals(*aIID);
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::GetNameShared(const char** aName)
+{
+    *aName = mName.get();
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::GetIIDShared(const nsIID** aIID)
+{
+    *aIID = &mIID;
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::IsFunction(bool* aRetVal)
+{
+    *aRetVal = false;
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+ShimInterfaceInfo::HasAncestor(const nsIID* aIID, bool* aRetVal)
+{
+    *aRetVal = false;
+    return NS_OK;
+}
+
+NS_IMETHODIMP_(nsresult)
+ShimInterfaceInfo::GetIIDForParamNoAlloc(uint16_t aIndex, const nsXPTParamInfo* aInfo, nsIID* aIID)
+{
+    MOZ_ASSERT(false, "This should never be called");
+    return NS_ERROR_NOT_IMPLEMENTED;
+}
diff --git a/xpcom/reflect/xptinfo/ShimInterfaceInfo.h b/xpcom/reflect/xptinfo/ShimInterfaceInfo.h
new file mode 100644
index 000000000..868f503a5
--- /dev/null
+++ b/xpcom/reflect/xptinfo/ShimInterfaceInfo.h
@@ -0,0 +1,50 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sw=4 et tw=78:
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef ShimInterfaceInfo_h
+#define ShimInterfaceInfo_h
+
+#include "mozilla/Attributes.h"
+#include "nsIInterfaceInfo.h"
+#include "nsString.h"
+#include "nsID.h"
+#include "nsTArray.h"
+#include "xptinfo.h"
+#include "nsAutoPtr.h"
+#include "js/RootingAPI.h"
+
+namespace mozilla {
+namespace dom {
+struct NativePropertyHooks;
+} // namespace dom
+} // namespace mozilla
+
+class ShimInterfaceInfo final : public nsIInterfaceInfo
+{
+public:
+    NS_DECL_ISUPPORTS
+    NS_DECL_NSIINTERFACEINFO
+
+    // Construct a ShimInterfaceInfo object if we have a shim available for aName.
+    // Otherwise, returns nullptr.
+    static already_AddRefed<ShimInterfaceInfo>
+    MaybeConstruct(const char* aName, JSContext* cx);
+
+private:
+    ShimInterfaceInfo(const nsIID& aIID,
+                      const char* aName,
+                      const mozilla::dom::NativePropertyHooks* aNativePropHooks);
+
+    ~ShimInterfaceInfo() {}
+
+private:
+    nsIID mIID;
+    nsAutoCString mName;
+    const mozilla::dom::NativePropertyHooks* mNativePropHooks;
+};
+
+#endif
diff --git a/xpcom/reflect/xptinfo/TODO b/xpcom/reflect/xptinfo/TODO
new file mode 100644
index 000000000..50215a4fb
--- /dev/null
+++ b/xpcom/reflect/xptinfo/TODO
@@ -0,0 +1,20 @@
+/* jband - 03/24/00 -  */
+
+- DOCS
+- improve error handling
+  - should some errors really be warnings?
+  - should autoreg support additional channel to receive warnings so that
+    an installer can decide whether or not to accept the consequences of 
+    leaving the newly installed files in place?
+- verification of interfaces (warnings and/or errors)
+  - verify that repeated interfaces are identical in all ways
+  - verify that interface names are always one-to-one with iids    
+- check for truncated xpt files and version problems
+  - http://bugzilla.mozilla.org/show_bug.cgi?id=33193
+- TESTS!
+   - e.g. verify the merge stuff really works for various inputs.
+   - we really need a set of .xpt and .zip files and code that does an array 
+     of autoreg and interfaceinof use activitities to test various corners
+     of the system.
+- better autoreg logging
+- use only 32 bits for file size?
diff --git a/xpcom/reflect/xptinfo/XPTInterfaceInfoManager.h b/xpcom/reflect/xptinfo/XPTInterfaceInfoManager.h
new file mode 100644
index 000000000..e72153ad2
--- /dev/null
+++ b/xpcom/reflect/xptinfo/XPTInterfaceInfoManager.h
@@ -0,0 +1,119 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* vim: set ts=4 et sw=4 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_XPTInterfaceInfoManager_h_
+#define mozilla_XPTInterfaceInfoManager_h_
+
+#include "nsIInterfaceInfoManager.h"
+#include "nsIMemoryReporter.h"
+
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/ReentrantMonitor.h"
+#include "nsDataHashtable.h"
+
+template<typename T> class nsCOMArray;
+class nsIMemoryReporter;
+struct XPTHeader;
+struct XPTInterfaceDirectoryEntry;
+class xptiInterfaceEntry;
+class xptiInterfaceInfo;
+class xptiTypelibGuts;
+
+namespace mozilla {
+
+class XPTInterfaceInfoManager final
+    : public nsIInterfaceInfoManager
+    , public nsIMemoryReporter
+{
+    NS_DECL_THREADSAFE_ISUPPORTS
+    NS_DECL_NSIINTERFACEINFOMANAGER
+    NS_DECL_NSIMEMORYREPORTER
+
+public:
+    // GetSingleton() is infallible
+    static XPTInterfaceInfoManager* GetSingleton();
+    static void FreeInterfaceInfoManager();
+
+    void GetScriptableInterfaces(nsCOMArray<nsIInterfaceInfo>& aInterfaces);
+
+    void RegisterBuffer(char *buf, uint32_t length);
+
+    static Mutex& GetResolveLock()
+    {
+        return GetSingleton()->mResolveLock;
+    }
+
+    xptiInterfaceEntry* GetInterfaceEntryForIID(const nsIID *iid);
+
+    size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf);
+
+private:
+    XPTInterfaceInfoManager();
+    ~XPTInterfaceInfoManager();
+
+    void InitMemoryReporter();
+
+    void RegisterXPTHeader(XPTHeader* aHeader);
+
+    // idx is the index of this interface in the XPTHeader
+    void VerifyAndAddEntryIfNew(XPTInterfaceDirectoryEntry* iface,
+                                uint16_t idx,
+                                xptiTypelibGuts* typelib);
+
+private:
+
+    class xptiWorkingSet
+    {
+    public:
+        xptiWorkingSet();
+        ~xptiWorkingSet();
+
+        bool IsValid() const;
+
+        void InvalidateInterfaceInfos();
+        void ClearHashTables();
+
+        // utility methods...
+
+        enum {NOT_FOUND = 0xffffffff};
+
+        // Directory stuff...
+
+        uint32_t GetDirectoryCount();
+        nsresult GetCloneOfDirectoryAt(uint32_t i, nsIFile** dir);
+        nsresult GetDirectoryAt(uint32_t i, nsIFile** dir);
+        bool     FindDirectory(nsIFile* dir, uint32_t* index);
+        bool     FindDirectoryOfFile(nsIFile* file, uint32_t* index);
+        bool     DirectoryAtMatchesPersistentDescriptor(uint32_t i, const char* desc);
+
+    private:
+        uint32_t        mFileCount;
+        uint32_t        mMaxFileCount;
+
+    public:
+        // XXX make these private with accessors
+        // mTableMonitor must be held across:
+        //  * any read from or write to mIIDTable or mNameTable
+        //  * any writing to the links between an xptiInterfaceEntry
+        //    and its xptiInterfaceInfo (mEntry/mInfo)
+        mozilla::ReentrantMonitor mTableReentrantMonitor;
+        nsDataHashtable<nsIDHashKey, xptiInterfaceEntry*> mIIDTable;
+        nsDataHashtable<nsDepCharHashKey, xptiInterfaceEntry*> mNameTable;
+    };
+
+    // XXX xptiInterfaceInfo want's to poke at the working set itself
+    friend class ::xptiInterfaceInfo;
+    friend class ::xptiInterfaceEntry;
+    friend class ::xptiTypelibGuts;
+
+    xptiWorkingSet               mWorkingSet;
+    Mutex                        mResolveLock;
+};
+
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/reflect/xptinfo/moz.build b/xpcom/reflect/xptinfo/moz.build
new file mode 100644
index 000000000..320949782
--- /dev/null
+++ b/xpcom/reflect/xptinfo/moz.build
@@ -0,0 +1,37 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+UNIFIED_SOURCES += [
+    'ShimInterfaceInfo.cpp',
+    'xptiInterfaceInfo.cpp',
+    'xptiInterfaceInfoManager.cpp',
+    'xptiTypelibGuts.cpp',
+    'xptiWorkingSet.cpp',
+]
+
+XPIDL_SOURCES += [
+    'nsIInterfaceInfo.idl',
+    'nsIInterfaceInfoManager.idl',
+]
+
+XPIDL_MODULE = 'xpcom_xpti'
+
+EXPORTS += [
+    'xptinfo.h',
+]
+
+EXPORTS.mozilla += [
+    'XPTInterfaceInfoManager.h',
+]
+
+LOCAL_INCLUDES += [
+    '/dom/base',
+]
+
+FINAL_LIBRARY = 'xul'
+
+if CONFIG['GNU_CXX']:
+    CXXFLAGS += ['-Wno-error=shadow']
diff --git a/xpcom/reflect/xptinfo/nsIInterfaceInfo.idl b/xpcom/reflect/xptinfo/nsIInterfaceInfo.idl
new file mode 100644
index 000000000..8b902d5ee
--- /dev/null
+++ b/xpcom/reflect/xptinfo/nsIInterfaceInfo.idl
@@ -0,0 +1,101 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* The nsIInterfaceInfo public declaration. */
+
+
+#include "nsISupports.idl"
+
+// forward declaration of non-XPCOM types
+
+[ptr] native nsXPTMethodInfoPtr(nsXPTMethodInfo);
+[ptr] native nsXPTParamInfoPtr(nsXPTParamInfo);
+      native nsXPTType(nsXPTType);
+
+// We bend the rules to do a [shared] nsIID (but this is never scriptable)
+[ptr] native nsIIDPtrShared(nsIID);
+
+%{C++
+class nsXPTMethodInfo;
+class nsXPTParamInfo;
+class nsXPTType;
+%}
+
+[builtinclass, uuid(3820e663-8e22-4789-b470-56bcf7083f2b)]
+interface nsIInterfaceInfo : nsISupports
+{
+    readonly attribute string   name;
+    readonly attribute nsIIDPtr InterfaceIID;
+
+    boolean isScriptable();
+    boolean isBuiltinClass();
+
+    readonly attribute nsIInterfaceInfo parent;
+
+    /**
+    * These include counts for parent (and all ancestors).
+    */
+    readonly attribute uint16_t methodCount;
+    readonly attribute uint16_t constantCount;
+
+    /**
+    * These include methods and constants for parent (and all ancestors).
+    *
+    * These do *not* make copies ***explicit bending of XPCOM rules***.
+    */
+
+    void getMethodInfo(in uint16_t index,
+                       [shared, retval] out nsXPTMethodInfoPtr info);
+
+    void getMethodInfoForName(in string methodName, out uint16_t index,
+                       [shared, retval] out nsXPTMethodInfoPtr info);
+
+    void getConstant(in uint16_t index,
+                     out jsval constant,
+                     out string name);
+
+
+    /**
+    * Get the interface information or iid associated with a param of some
+    * method in this interface.
+    */
+
+    nsIInterfaceInfo getInfoForParam(in uint16_t methodIndex,
+                                     [const] in nsXPTParamInfoPtr param);
+
+    nsIIDPtr getIIDForParam(in uint16_t methodIndex,
+                            [const] in nsXPTParamInfoPtr param);
+
+
+    /**
+    * These do *not* make copies ***explicit bending of XPCOM rules***.
+    */
+
+    nsXPTType getTypeForParam(in uint16_t methodIndex,
+                              [const] in nsXPTParamInfoPtr param,
+                              in uint16_t dimension);
+
+    uint8_t getSizeIsArgNumberForParam(in uint16_t methodIndex,
+                                       [const] in nsXPTParamInfoPtr param,
+                                       in uint16_t dimension);
+
+    uint8_t getInterfaceIsArgNumberForParam(in uint16_t methodIndex,
+                                            [const] in nsXPTParamInfoPtr param);
+
+    boolean isIID(in nsIIDPtr IID);
+
+    void   getNameShared([shared,retval] out string name);
+    void   getIIDShared([shared,retval] out nsIIDPtrShared iid);
+
+    boolean isFunction();
+
+    boolean hasAncestor(in nsIIDPtr iid);
+
+    [notxpcom] nsresult getIIDForParamNoAlloc(in uint16_t methodIndex,
+                                              [const] in nsXPTParamInfoPtr param,
+                                              out nsIID iid);
+
+    boolean isMainProcessScriptableOnly();
+};
diff --git a/xpcom/reflect/xptinfo/nsIInterfaceInfoManager.idl b/xpcom/reflect/xptinfo/nsIInterfaceInfoManager.idl
new file mode 100644
index 000000000..bc63aed49
--- /dev/null
+++ b/xpcom/reflect/xptinfo/nsIInterfaceInfoManager.idl
@@ -0,0 +1,28 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* The nsIInterfaceInfoManager public declaration. */
+
+
+#include "nsISupports.idl"
+
+interface nsIInterfaceInfo;
+
+[builtinclass, uuid(1d53d8d9-1d92-428f-b5cc-198b55e897d7)]
+interface nsIInterfaceInfoManager : nsISupports
+{
+    nsIInterfaceInfo getInfoForIID(in nsIIDPtr iid);
+    nsIInterfaceInfo getInfoForName(in string name);
+};
+
+%{C++
+#define NS_INTERFACEINFOMANAGER_SERVICE_CID            \
+ { /* 13bef784-f8e0-4f96-85c1-09f9ef4f9a19 */          \
+  0x13bef784, 0xf8e0, 0x4f96,                          \
+  {0x85, 0xc1, 0x09, 0xf9, 0xef, 0x4f, 0x9a, 0x19} }
+
+#define NS_INTERFACEINFOMANAGER_SERVICE_CONTRACTID  \
+   "@mozilla.org/xpti/interfaceinfomanager-service;1"
+%}
diff --git a/xpcom/reflect/xptinfo/xptiInterfaceInfo.cpp b/xpcom/reflect/xptinfo/xptiInterfaceInfo.cpp
new file mode 100644
index 000000000..8ea80fda1
--- /dev/null
+++ b/xpcom/reflect/xptinfo/xptiInterfaceInfo.cpp
@@ -0,0 +1,742 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implementation of xptiInterfaceEntry and xptiInterfaceInfo. */
+
+#include "xptiprivate.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/XPTInterfaceInfoManager.h"
+#include "mozilla/PodOperations.h"
+#include "jsapi.h"
+
+using namespace mozilla;
+
+/* static */ xptiInterfaceEntry*
+xptiInterfaceEntry::Create(const char* name, const nsID& iid,
+                           XPTInterfaceDescriptor* aDescriptor,
+                           xptiTypelibGuts* aTypelib)
+{
+    int namelen = strlen(name);
+    void* place =
+        XPT_CALLOC8(gXPTIStructArena, sizeof(xptiInterfaceEntry) + namelen);
+    if (!place) {
+        return nullptr;
+    }
+    return new (place) xptiInterfaceEntry(name, namelen, iid, aDescriptor,
+                                          aTypelib);
+}
+
+xptiInterfaceEntry::xptiInterfaceEntry(const char* name,
+                                       size_t nameLength,
+                                       const nsID& iid,
+                                       XPTInterfaceDescriptor* aDescriptor,
+                                       xptiTypelibGuts* aTypelib)
+    : mIID(iid)
+    , mDescriptor(aDescriptor)
+    , mTypelib(aTypelib)
+    , mParent(nullptr)
+    , mInfo(nullptr)
+    , mMethodBaseIndex(0)
+    , mConstantBaseIndex(0)
+    , mFlags(0)
+{
+    memcpy(mName, name, nameLength);
+    SetResolvedState(PARTIALLY_RESOLVED);
+}
+
+bool 
+xptiInterfaceEntry::Resolve()
+{
+    MutexAutoLock lock(XPTInterfaceInfoManager::GetResolveLock());
+    return ResolveLocked();
+}
+
+bool 
+xptiInterfaceEntry::ResolveLocked()
+{
+    int resolvedState = GetResolveState();
+
+    if(resolvedState == FULLY_RESOLVED)
+        return true;
+    if(resolvedState == RESOLVE_FAILED)
+        return false;
+
+    NS_ASSERTION(GetResolveState() == PARTIALLY_RESOLVED, "bad state!");    
+
+    // Finish out resolution by finding parent and Resolving it so
+    // we can set the info we get from it.
+
+    uint16_t parent_index = mDescriptor->parent_interface;
+
+    if(parent_index)
+    {
+        xptiInterfaceEntry* parent = 
+            mTypelib->GetEntryAt(parent_index - 1);
+        
+        if(!parent || !parent->EnsureResolvedLocked())
+        {
+            SetResolvedState(RESOLVE_FAILED);
+            return false;
+        }
+
+        mParent = parent;
+        if (parent->GetHasNotXPCOMFlag()) {
+            SetHasNotXPCOMFlag();
+        } else {
+            for (uint16_t idx = 0; idx < mDescriptor->num_methods; ++idx) {
+                nsXPTMethodInfo* method = reinterpret_cast<nsXPTMethodInfo*>(
+                    mDescriptor->method_descriptors + idx);
+                if (method->IsNotXPCOM()) {
+                    SetHasNotXPCOMFlag();
+                    break;
+                }
+            }
+        }
+
+
+        mMethodBaseIndex =
+            parent->mMethodBaseIndex + 
+            parent->mDescriptor->num_methods;
+        
+        mConstantBaseIndex =
+            parent->mConstantBaseIndex + 
+            parent->mDescriptor->num_constants;
+
+    }
+    LOG_RESOLVE(("+ complete resolve of %s\n", mName));
+
+    SetResolvedState(FULLY_RESOLVED);
+    return true;
+}        
+
+/**************************************************/
+// These non-virtual methods handle the delegated nsIInterfaceInfo methods.
+
+nsresult
+xptiInterfaceEntry::GetName(char **name)
+{
+    // It is not necessary to Resolve because this info is read from manifest.
+    *name = (char*) nsMemory::Clone(mName, strlen(mName)+1);
+    return *name ? NS_OK : NS_ERROR_OUT_OF_MEMORY;
+}
+
+nsresult
+xptiInterfaceEntry::GetIID(nsIID **iid)
+{
+    // It is not necessary to Resolve because this info is read from manifest.
+    *iid = (nsIID*) nsMemory::Clone(&mIID, sizeof(nsIID));
+    return *iid ? NS_OK : NS_ERROR_OUT_OF_MEMORY;
+}
+
+nsresult
+xptiInterfaceEntry::IsScriptable(bool* result)
+{
+    // It is not necessary to Resolve because this info is read from manifest.
+    *result = GetScriptableFlag();
+    return NS_OK;
+}
+
+nsresult
+xptiInterfaceEntry::IsFunction(bool* result)
+{
+    if(!EnsureResolved())
+        return NS_ERROR_UNEXPECTED;
+
+    *result = XPT_ID_IS_FUNCTION(mDescriptor->flags);
+    return NS_OK;
+}
+
+nsresult
+xptiInterfaceEntry::GetMethodCount(uint16_t* count)
+{
+    if(!EnsureResolved())
+        return NS_ERROR_UNEXPECTED;
+    
+    *count = mMethodBaseIndex + 
+             mDescriptor->num_methods;
+    return NS_OK;
+}
+
+nsresult
+xptiInterfaceEntry::GetConstantCount(uint16_t* count)
+{
+    if(!EnsureResolved())
+        return NS_ERROR_UNEXPECTED;
+
+    if(!count)
+        return NS_ERROR_UNEXPECTED;
+
+    *count = mConstantBaseIndex + 
+             mDescriptor->num_constants;
+    return NS_OK;
+}
+
+nsresult
+xptiInterfaceEntry::GetMethodInfo(uint16_t index, const nsXPTMethodInfo** info)
+{
+    if(!EnsureResolved())
+        return NS_ERROR_UNEXPECTED;
+
+    if(index < mMethodBaseIndex)
+        return mParent->GetMethodInfo(index, info);
+
+    if(index >= mMethodBaseIndex + 
+                mDescriptor->num_methods)
+    {
+        NS_ERROR("bad param");
+        *info = nullptr;
+        return NS_ERROR_INVALID_ARG;
+    }
+
+    // else...
+    *info = reinterpret_cast<nsXPTMethodInfo*>
+       (&mDescriptor->method_descriptors[index - mMethodBaseIndex]);
+    return NS_OK;
+}
+
+nsresult
+xptiInterfaceEntry::GetMethodInfoForName(const char* methodName, uint16_t *index,
+                                         const nsXPTMethodInfo** result)
+{
+    if(!EnsureResolved())
+        return NS_ERROR_UNEXPECTED;
+
+    // This is a slow algorithm, but this is not expected to be called much.
+    for(uint16_t i = 0; i < mDescriptor->num_methods; ++i)
+    {
+        const nsXPTMethodInfo* info;
+        info = reinterpret_cast<nsXPTMethodInfo*>
+                               (&mDescriptor->
+                                        method_descriptors[i]);
+        if (PL_strcmp(methodName, info->GetName()) == 0) {
+            *index = i + mMethodBaseIndex;
+            *result = info;
+            return NS_OK;
+        }
+    }
+    
+    if(mParent)
+        return mParent->GetMethodInfoForName(methodName, index, result);
+    else
+    {
+        *index = 0;
+        *result = 0;
+        return NS_ERROR_INVALID_ARG;
+    }
+}
+
+nsresult
+xptiInterfaceEntry::GetConstant(uint16_t index, JS::MutableHandleValue constant,
+                                char** name)
+{
+    if(!EnsureResolved())
+        return NS_ERROR_UNEXPECTED;
+
+    if(index < mConstantBaseIndex)
+        return mParent->GetConstant(index, constant, name);
+
+    if(index >= mConstantBaseIndex + 
+                mDescriptor->num_constants)
+    {
+        NS_PRECONDITION(0, "bad param");
+        return NS_ERROR_INVALID_ARG;
+    }
+
+    const auto& c = mDescriptor->const_descriptors[index - mConstantBaseIndex];
+    AutoJSContext cx;
+    JS::Rooted<JS::Value> v(cx);
+    v.setUndefined();
+
+    switch (c.type.prefix.flags) {
+      case nsXPTType::T_I8:
+      {
+        v.setInt32(c.value.i8);
+        break;
+      }
+      case nsXPTType::T_U8:
+      {
+        v.setInt32(c.value.ui8);
+        break;
+      }
+      case nsXPTType::T_I16:
+      {
+        v.setInt32(c.value.i16);
+        break;
+      }
+      case nsXPTType::T_U16:
+      {
+        v.setInt32(c.value.ui16);
+        break;
+      }
+      case nsXPTType::T_I32:
+      {
+        v = JS_NumberValue(c.value.i32);
+        break;
+      }
+      case nsXPTType::T_U32:
+      {
+        v = JS_NumberValue(c.value.ui32);
+        break;
+      }
+      default:
+      {
+#ifdef DEBUG
+        NS_ERROR("Non-numeric constant found in interface.");
+#endif
+      }
+    }
+
+    constant.set(v);
+    *name = ToNewCString(nsDependentCString(c.name));
+
+    return NS_OK;
+}
+
+// this is a private helper
+
+nsresult
+xptiInterfaceEntry::GetInterfaceIndexForParam(uint16_t methodIndex,
+                                              const nsXPTParamInfo* param,
+                                              uint16_t* interfaceIndex)
+{
+    if(!EnsureResolved())
+        return NS_ERROR_UNEXPECTED;
+
+    if(methodIndex < mMethodBaseIndex)
+        return mParent->GetInterfaceIndexForParam(methodIndex, param,
+                                                  interfaceIndex);
+
+    if(methodIndex >= mMethodBaseIndex + 
+                      mDescriptor->num_methods)
+    {
+        NS_ERROR("bad param");
+        return NS_ERROR_INVALID_ARG;
+    }
+
+    const XPTTypeDescriptor *td = &param->type;
+
+    while (XPT_TDP_TAG(td->prefix) == TD_ARRAY) {
+        td = &mDescriptor->additional_types[td->u.array.additional_type];
+    }
+
+    if(XPT_TDP_TAG(td->prefix) != TD_INTERFACE_TYPE) {
+        NS_ERROR("not an interface");
+        return NS_ERROR_INVALID_ARG;
+    }
+
+    *interfaceIndex = (td->u.iface.iface_hi8 << 8) | td->u.iface.iface_lo8;
+    return NS_OK;
+}
+
+nsresult 
+xptiInterfaceEntry::GetEntryForParam(uint16_t methodIndex, 
+                                     const nsXPTParamInfo * param,
+                                     xptiInterfaceEntry** entry)
+{
+    if(!EnsureResolved())
+        return NS_ERROR_UNEXPECTED;
+
+    if(methodIndex < mMethodBaseIndex)
+        return mParent->GetEntryForParam(methodIndex, param, entry);
+
+    uint16_t interfaceIndex = 0;
+    nsresult rv = GetInterfaceIndexForParam(methodIndex, param,
+                                            &interfaceIndex);
+    if (NS_FAILED(rv)) {
+        return rv;
+    }
+
+    xptiInterfaceEntry* theEntry = mTypelib->GetEntryAt(interfaceIndex - 1);
+    
+    // This can happen if a declared interface is not available at runtime.
+    if(!theEntry)
+    {
+        *entry = nullptr;
+        return NS_ERROR_FAILURE;
+    }
+
+    *entry = theEntry;
+    return NS_OK;
+}
+
+already_AddRefed<ShimInterfaceInfo>
+xptiInterfaceEntry::GetShimForParam(uint16_t methodIndex,
+                                    const nsXPTParamInfo* param)
+{
+    if(methodIndex < mMethodBaseIndex) {
+        return mParent->GetShimForParam(methodIndex, param);
+    }
+
+    uint16_t interfaceIndex = 0;
+    nsresult rv = GetInterfaceIndexForParam(methodIndex, param,
+                                            &interfaceIndex);
+    if (NS_FAILED(rv)) {
+        return nullptr;
+    }
+
+    const char* shimName = mTypelib->GetEntryNameAt(interfaceIndex - 1);
+    RefPtr<ShimInterfaceInfo> shim =
+        ShimInterfaceInfo::MaybeConstruct(shimName, nullptr);
+    return shim.forget();
+}
+
+nsresult
+xptiInterfaceEntry::GetInfoForParam(uint16_t methodIndex,
+                                    const nsXPTParamInfo *param,
+                                    nsIInterfaceInfo** info)
+{
+    xptiInterfaceEntry* entry;
+    nsresult rv = GetEntryForParam(methodIndex, param, &entry);
+    if (NS_FAILED(rv)) {
+        RefPtr<ShimInterfaceInfo> shim = GetShimForParam(methodIndex, param);
+        if (!shim) {
+            return rv;
+        }
+
+        shim.forget(info);
+        return NS_OK;
+    }
+
+    *info = entry->InterfaceInfo().take();
+
+    return NS_OK;
+}
+
+nsresult
+xptiInterfaceEntry::GetIIDForParam(uint16_t methodIndex,
+                                   const nsXPTParamInfo* param, nsIID** iid)
+{
+    xptiInterfaceEntry* entry;
+    nsresult rv = GetEntryForParam(methodIndex, param, &entry);
+    if (NS_FAILED(rv)) {
+        RefPtr<ShimInterfaceInfo> shim = GetShimForParam(methodIndex, param);
+        if (!shim) {
+            return rv;
+        }
+
+        return shim->GetInterfaceIID(iid);
+    }
+    return entry->GetIID(iid);
+}
+
+nsresult
+xptiInterfaceEntry::GetIIDForParamNoAlloc(uint16_t methodIndex, 
+                                          const nsXPTParamInfo * param, 
+                                          nsIID *iid)
+{
+    xptiInterfaceEntry* entry;
+    nsresult rv = GetEntryForParam(methodIndex, param, &entry);
+    if (NS_FAILED(rv)) {
+        RefPtr<ShimInterfaceInfo> shim = GetShimForParam(methodIndex, param);
+        if (!shim) {
+            return rv;
+        }
+
+        const nsIID* shimIID;
+        DebugOnly<nsresult> rv2 = shim->GetIIDShared(&shimIID);
+        MOZ_ASSERT(NS_SUCCEEDED(rv2));
+        *iid = *shimIID;
+        return NS_OK;
+    }
+    *iid = entry->mIID;    
+    return NS_OK;
+}
+
+// this is a private helper
+nsresult
+xptiInterfaceEntry::GetTypeInArray(const nsXPTParamInfo* param,
+                                  uint16_t dimension,
+                                  const XPTTypeDescriptor** type)
+{
+    NS_ASSERTION(IsFullyResolved(), "bad state");
+
+    const XPTTypeDescriptor *td = &param->type;
+    const XPTTypeDescriptor *additional_types =
+                mDescriptor->additional_types;
+
+    for (uint16_t i = 0; i < dimension; i++) {
+        if(XPT_TDP_TAG(td->prefix) != TD_ARRAY) {
+            NS_ERROR("bad dimension");
+            return NS_ERROR_INVALID_ARG;
+        }
+        td = &additional_types[td->u.array.additional_type];
+    }
+
+    *type = td;
+    return NS_OK;
+}
+
+nsresult
+xptiInterfaceEntry::GetTypeForParam(uint16_t methodIndex,
+                                    const nsXPTParamInfo* param,
+                                    uint16_t dimension,
+                                    nsXPTType* type)
+{
+    if(!EnsureResolved())
+        return NS_ERROR_UNEXPECTED;
+
+    if(methodIndex < mMethodBaseIndex)
+        return mParent->
+            GetTypeForParam(methodIndex, param, dimension, type);
+
+    if(methodIndex >= mMethodBaseIndex + 
+                      mDescriptor->num_methods)
+    {
+        NS_ERROR("bad index");
+        return NS_ERROR_INVALID_ARG;
+    }
+
+    const XPTTypeDescriptor *td;
+
+    if(dimension) {
+        nsresult rv = GetTypeInArray(param, dimension, &td);
+        if(NS_FAILED(rv))
+            return rv;
+    }
+    else
+        td = &param->type;
+
+    *type = nsXPTType(td->prefix);
+    return NS_OK;
+}
+
+nsresult
+xptiInterfaceEntry::GetSizeIsArgNumberForParam(uint16_t methodIndex,
+                                               const nsXPTParamInfo* param,
+                                               uint16_t dimension,
+                                               uint8_t* argnum)
+{
+    if(!EnsureResolved())
+        return NS_ERROR_UNEXPECTED;
+
+    if(methodIndex < mMethodBaseIndex)
+        return mParent->
+            GetSizeIsArgNumberForParam(methodIndex, param, dimension, argnum);
+
+    if(methodIndex >= mMethodBaseIndex + 
+                      mDescriptor->num_methods)
+    {
+        NS_ERROR("bad index");
+        return NS_ERROR_INVALID_ARG;
+    }
+
+    const XPTTypeDescriptor *td;
+
+    if(dimension) {
+        nsresult rv = GetTypeInArray(param, dimension, &td);
+        if(NS_FAILED(rv))
+            return rv;
+    }
+    else
+        td = &param->type;
+
+    // verify that this is a type that has size_is
+    switch (XPT_TDP_TAG(td->prefix)) {
+      case TD_ARRAY:
+        *argnum = td->u.array.argnum;
+        break;
+      case TD_PSTRING_SIZE_IS:
+      case TD_PWSTRING_SIZE_IS:
+        *argnum = td->u.pstring_is.argnum;
+        break;
+      default:
+        NS_ERROR("not a size_is");
+        return NS_ERROR_INVALID_ARG;
+    }
+
+    return NS_OK;
+}
+
+nsresult
+xptiInterfaceEntry::GetInterfaceIsArgNumberForParam(uint16_t methodIndex,
+                                                    const nsXPTParamInfo* param,
+                                                    uint8_t* argnum)
+{
+    if(!EnsureResolved())
+        return NS_ERROR_UNEXPECTED;
+
+    if(methodIndex < mMethodBaseIndex)
+        return mParent->
+            GetInterfaceIsArgNumberForParam(methodIndex, param, argnum);
+
+    if(methodIndex >= mMethodBaseIndex + 
+                      mDescriptor->num_methods)
+    {
+        NS_ERROR("bad index");
+        return NS_ERROR_INVALID_ARG;
+    }
+
+    const XPTTypeDescriptor *td = &param->type;
+
+    while (XPT_TDP_TAG(td->prefix) == TD_ARRAY) {
+        td = &mDescriptor->additional_types[td->u.array.additional_type];
+    }
+
+    if(XPT_TDP_TAG(td->prefix) != TD_INTERFACE_IS_TYPE) {
+        NS_ERROR("not an iid_is");
+        return NS_ERROR_INVALID_ARG;
+    }
+
+    *argnum = td->u.interface_is.argnum;
+    return NS_OK;
+}
+
+nsresult
+xptiInterfaceEntry::IsIID(const nsIID * iid, bool *_retval)
+{
+    // It is not necessary to Resolve because this info is read from manifest.
+    *_retval = mIID.Equals(*iid);
+    return NS_OK;
+}
+
+nsresult 
+xptiInterfaceEntry::GetNameShared(const char **name)
+{
+    // It is not necessary to Resolve because this info is read from manifest.
+    *name = mName;
+    return NS_OK;
+}
+
+nsresult 
+xptiInterfaceEntry::GetIIDShared(const nsIID * *iid)
+{
+    // It is not necessary to Resolve because this info is read from manifest.
+    *iid = &mIID;
+    return NS_OK;
+}
+
+nsresult 
+xptiInterfaceEntry::HasAncestor(const nsIID * iid, bool *_retval)
+{
+    *_retval = false;
+
+    for(xptiInterfaceEntry* current = this; 
+        current;
+        current = current->mParent)
+    {
+        if(current->mIID.Equals(*iid))
+        {
+            *_retval = true;
+            break;
+        }
+        if(!current->EnsureResolved())
+            return NS_ERROR_UNEXPECTED;
+    }
+
+    return NS_OK;
+}
+
+/***************************************************/
+
+already_AddRefed<xptiInterfaceInfo> 
+xptiInterfaceEntry::InterfaceInfo()
+{
+#ifdef DEBUG
+    XPTInterfaceInfoManager::GetSingleton()->mWorkingSet.mTableReentrantMonitor.
+        AssertCurrentThreadIn();
+#endif
+
+    if(!mInfo)
+    {
+        mInfo = new xptiInterfaceInfo(this);
+    }
+    
+    RefPtr<xptiInterfaceInfo> info = mInfo;
+    return info.forget();
+}
+    
+void     
+xptiInterfaceEntry::LockedInvalidateInterfaceInfo()
+{
+    if(mInfo)
+    {
+        mInfo->Invalidate(); 
+        mInfo = nullptr;
+    }
+}
+
+bool
+xptiInterfaceInfo::BuildParent()
+{
+    mozilla::ReentrantMonitorAutoEnter monitor(XPTInterfaceInfoManager::GetSingleton()->
+                                    mWorkingSet.mTableReentrantMonitor);
+    NS_ASSERTION(mEntry &&
+                 mEntry->IsFullyResolved() &&
+                 !mParent &&
+                 mEntry->Parent(),
+                "bad BuildParent call");
+    mParent = mEntry->Parent()->InterfaceInfo();
+    return true;
+}
+
+/***************************************************************************/
+
+NS_IMPL_QUERY_INTERFACE(xptiInterfaceInfo, nsIInterfaceInfo)
+
+xptiInterfaceInfo::xptiInterfaceInfo(xptiInterfaceEntry* entry)
+    : mEntry(entry)
+{
+}
+
+xptiInterfaceInfo::~xptiInterfaceInfo() 
+{
+    NS_ASSERTION(!mEntry, "bad state in dtor");
+}
+
+void
+xptiInterfaceInfo::Invalidate()
+{
+  mParent = nullptr;
+  mEntry = nullptr;
+}
+
+MozExternalRefCountType
+xptiInterfaceInfo::AddRef(void)
+{
+    nsrefcnt cnt = ++mRefCnt;
+    NS_LOG_ADDREF(this, cnt, "xptiInterfaceInfo", sizeof(*this));
+    return cnt;
+}
+
+MozExternalRefCountType
+xptiInterfaceInfo::Release(void)
+{
+    xptiInterfaceEntry* entry = mEntry;
+    nsrefcnt cnt = --mRefCnt;
+    NS_LOG_RELEASE(this, cnt, "xptiInterfaceInfo");
+    if(!cnt)
+    {
+        mozilla::ReentrantMonitorAutoEnter monitor(XPTInterfaceInfoManager::
+                                          GetSingleton()->mWorkingSet.
+                                          mTableReentrantMonitor);
+
+        // If InterfaceInfo added and *released* a reference before we 
+        // acquired the monitor then 'this' might already be dead. In that
+        // case we would not want to try to access any instance data. We
+        // would want to bail immediately. If 'this' is already dead then the
+        // entry will no longer have a pointer to 'this'. So, we can protect 
+        // ourselves from danger without more aggressive locking.
+        if(entry && !entry->InterfaceInfoEquals(this))
+            return 0;
+
+        // If InterfaceInfo added a reference before we acquired the monitor
+        // then we want to bail out of here without destorying the object.
+        if(mRefCnt)
+            return 1;
+
+        if(mEntry)
+        {
+            mEntry->LockedInterfaceInfoDeathNotification();
+            mEntry = nullptr;
+        }
+
+        delete this;
+        return 0;    
+    }
+    return cnt;
+}
+
+/***************************************************************************/
diff --git a/xpcom/reflect/xptinfo/xptiInterfaceInfoManager.cpp b/xpcom/reflect/xptinfo/xptiInterfaceInfoManager.cpp
new file mode 100644
index 000000000..600a99b94
--- /dev/null
+++ b/xpcom/reflect/xptinfo/xptiInterfaceInfoManager.cpp
@@ -0,0 +1,242 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* vim: set ts=8 sts=4 et sw=4 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implementation of xptiInterfaceInfoManager. */
+
+#include "mozilla/XPTInterfaceInfoManager.h"
+
+#include "mozilla/FileUtils.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/StaticPtr.h"
+
+#include "xptiprivate.h"
+#include "nsDependentString.h"
+#include "nsString.h"
+#include "nsArrayEnumerator.h"
+#include "nsDirectoryService.h"
+#include "nsIMemoryReporter.h"
+
+using namespace mozilla;
+
+NS_IMPL_ISUPPORTS(
+  XPTInterfaceInfoManager,
+  nsIInterfaceInfoManager,
+  nsIMemoryReporter)
+
+static StaticRefPtr<XPTInterfaceInfoManager> gInterfaceInfoManager;
+
+size_t
+XPTInterfaceInfoManager::SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf)
+{
+    size_t n = aMallocSizeOf(this);
+    ReentrantMonitorAutoEnter monitor(mWorkingSet.mTableReentrantMonitor);
+    // The entries themselves are allocated out of an arena accounted
+    // for elsewhere, so don't measure them
+    n += mWorkingSet.mIIDTable.ShallowSizeOfExcludingThis(aMallocSizeOf);
+    n += mWorkingSet.mNameTable.ShallowSizeOfExcludingThis(aMallocSizeOf);
+    return n;
+}
+
+MOZ_DEFINE_MALLOC_SIZE_OF(XPTIMallocSizeOf)
+
+NS_IMETHODIMP
+XPTInterfaceInfoManager::CollectReports(nsIHandleReportCallback* aHandleReport,
+                                        nsISupports* aData, bool aAnonymize)
+{
+    size_t amount = SizeOfIncludingThis(XPTIMallocSizeOf);
+
+    // Measure gXPTIStructArena here, too.  This is a bit grotty because it
+    // doesn't belong to the XPTIInterfaceInfoManager, but there's no
+    // obviously better place to measure it.
+    amount += XPT_SizeOfArenaIncludingThis(gXPTIStructArena, XPTIMallocSizeOf);
+
+    MOZ_COLLECT_REPORT(
+        "explicit/xpti-working-set", KIND_HEAP, UNITS_BYTES, amount,
+        "Memory used by the XPCOM typelib system.");
+
+    return NS_OK;
+}
+
+// static
+XPTInterfaceInfoManager*
+XPTInterfaceInfoManager::GetSingleton()
+{
+    if (!gInterfaceInfoManager) {
+        gInterfaceInfoManager = new XPTInterfaceInfoManager();
+        gInterfaceInfoManager->InitMemoryReporter();
+    }
+    return gInterfaceInfoManager;
+}
+
+void
+XPTInterfaceInfoManager::FreeInterfaceInfoManager()
+{
+    gInterfaceInfoManager = nullptr;
+}
+
+XPTInterfaceInfoManager::XPTInterfaceInfoManager()
+    :   mWorkingSet(),
+        mResolveLock("XPTInterfaceInfoManager.mResolveLock")
+{
+}
+
+XPTInterfaceInfoManager::~XPTInterfaceInfoManager()
+{
+    // We only do this on shutdown of the service.
+    mWorkingSet.InvalidateInterfaceInfos();
+
+    UnregisterWeakMemoryReporter(this);
+}
+
+void
+XPTInterfaceInfoManager::InitMemoryReporter()
+{
+    RegisterWeakMemoryReporter(this);
+}
+
+void
+XPTInterfaceInfoManager::RegisterBuffer(char *buf, uint32_t length)
+{
+    XPTState state;
+    XPT_InitXDRState(&state, buf, length);
+
+    XPTCursor curs;
+    NotNull<XPTCursor*> cursor = WrapNotNull(&curs);
+    if (!XPT_MakeCursor(&state, XPT_HEADER, 0, cursor)) {
+        return;
+    }
+
+    XPTHeader *header = nullptr;
+    if (XPT_DoHeader(gXPTIStructArena, cursor, &header)) {
+        RegisterXPTHeader(header);
+    }
+}
+
+void
+XPTInterfaceInfoManager::RegisterXPTHeader(XPTHeader* aHeader)
+{
+    if (aHeader->major_version >= XPT_MAJOR_INCOMPATIBLE_VERSION) {
+        NS_ASSERTION(!aHeader->num_interfaces,"bad libxpt");
+        LOG_AUTOREG(("      file is version %d.%d  Type file of version %d.0 or higher can not be read.\n", (int)header->major_version, (int)header->minor_version, (int)XPT_MAJOR_INCOMPATIBLE_VERSION));
+    }
+
+    xptiTypelibGuts* typelib = xptiTypelibGuts::Create(aHeader);
+
+    ReentrantMonitorAutoEnter monitor(mWorkingSet.mTableReentrantMonitor);
+    for(uint16_t k = 0; k < aHeader->num_interfaces; k++)
+        VerifyAndAddEntryIfNew(aHeader->interface_directory + k, k, typelib);
+}
+
+void
+XPTInterfaceInfoManager::VerifyAndAddEntryIfNew(XPTInterfaceDirectoryEntry* iface,
+                                                uint16_t idx,
+                                                xptiTypelibGuts* typelib)
+{
+    if (!iface->interface_descriptor)
+        return;
+
+    // The number of maximum methods is not arbitrary. It is the same value as
+    // in xpcom/reflect/xptcall/genstubs.pl; do not change this value
+    // without changing that one or you WILL see problems.
+    if (iface->interface_descriptor->num_methods > 250 &&
+            !(XPT_ID_IS_BUILTINCLASS(iface->interface_descriptor->flags))) {
+        NS_ASSERTION(0, "Too many methods to handle for the stub, cannot load");
+        fprintf(stderr, "ignoring too large interface: %s\n", iface->name);
+        return;
+    }
+
+    mWorkingSet.mTableReentrantMonitor.AssertCurrentThreadIn();
+    xptiInterfaceEntry* entry = mWorkingSet.mIIDTable.Get(iface->iid);
+    if (entry) {
+        // XXX validate this info to find possible inconsistencies
+        LOG_AUTOREG(("      ignoring repeated interface: %s\n", iface->name));
+        return;
+    }
+
+    // Build a new xptiInterfaceEntry object and hook it up.
+
+    entry = xptiInterfaceEntry::Create(iface->name,
+                                       iface->iid,
+                                       iface->interface_descriptor,
+                                       typelib);
+    if (!entry)
+        return;
+
+    //XXX  We should SetHeader too as part of the validation, no?
+    entry->SetScriptableFlag(XPT_ID_IS_SCRIPTABLE(iface->interface_descriptor->flags));
+    entry->SetBuiltinClassFlag(XPT_ID_IS_BUILTINCLASS(iface->interface_descriptor->flags));
+    entry->SetMainProcessScriptableOnlyFlag(
+      XPT_ID_IS_MAIN_PROCESS_SCRIPTABLE_ONLY(iface->interface_descriptor->flags));
+
+    mWorkingSet.mIIDTable.Put(entry->IID(), entry);
+    mWorkingSet.mNameTable.Put(entry->GetTheName(), entry);
+
+    typelib->SetEntryAt(idx, entry);
+
+    LOG_AUTOREG(("      added interface: %s\n", iface->name));
+}
+
+// this is a private helper
+static nsresult
+EntryToInfo(xptiInterfaceEntry* entry, nsIInterfaceInfo **_retval)
+{
+    if (!entry) {
+        *_retval = nullptr;
+        return NS_ERROR_FAILURE;
+    }
+
+    RefPtr<xptiInterfaceInfo> info = entry->InterfaceInfo();
+    info.forget(_retval);
+    return NS_OK;
+}
+
+xptiInterfaceEntry*
+XPTInterfaceInfoManager::GetInterfaceEntryForIID(const nsIID *iid)
+{
+    ReentrantMonitorAutoEnter monitor(mWorkingSet.mTableReentrantMonitor);
+    return mWorkingSet.mIIDTable.Get(*iid);
+}
+
+NS_IMETHODIMP
+XPTInterfaceInfoManager::GetInfoForIID(const nsIID * iid, nsIInterfaceInfo **_retval)
+{
+    NS_ASSERTION(iid, "bad param");
+    NS_ASSERTION(_retval, "bad param");
+
+    ReentrantMonitorAutoEnter monitor(mWorkingSet.mTableReentrantMonitor);
+    xptiInterfaceEntry* entry = mWorkingSet.mIIDTable.Get(*iid);
+    return EntryToInfo(entry, _retval);
+}
+
+NS_IMETHODIMP
+XPTInterfaceInfoManager::GetInfoForName(const char *name, nsIInterfaceInfo **_retval)
+{
+    NS_ASSERTION(name, "bad param");
+    NS_ASSERTION(_retval, "bad param");
+
+    ReentrantMonitorAutoEnter monitor(mWorkingSet.mTableReentrantMonitor);
+    xptiInterfaceEntry* entry = mWorkingSet.mNameTable.Get(name);
+    return EntryToInfo(entry, _retval);
+}
+
+void
+XPTInterfaceInfoManager::GetScriptableInterfaces(nsCOMArray<nsIInterfaceInfo>& aInterfaces)
+{
+    // I didn't want to incur the size overhead of using nsHashtable just to
+    // make building an enumerator easier. So, this code makes a snapshot of
+    // the table using an nsCOMArray and builds an enumerator for that.
+    // We can afford this transient cost.
+
+    ReentrantMonitorAutoEnter monitor(mWorkingSet.mTableReentrantMonitor);
+    aInterfaces.SetCapacity(mWorkingSet.mNameTable.Count());
+    for (auto iter = mWorkingSet.mNameTable.Iter(); !iter.Done(); iter.Next()) {
+        xptiInterfaceEntry* entry = iter.UserData();
+        if (entry->GetScriptableFlag()) {
+            nsCOMPtr<nsIInterfaceInfo> ii = entry->InterfaceInfo();
+            aInterfaces.AppendElement(ii);
+        }
+    }
+}
diff --git a/xpcom/reflect/xptinfo/xptiTypelibGuts.cpp b/xpcom/reflect/xptinfo/xptiTypelibGuts.cpp
new file mode 100644
index 000000000..e2965d0b1
--- /dev/null
+++ b/xpcom/reflect/xptinfo/xptiTypelibGuts.cpp
@@ -0,0 +1,74 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implementation of xptiTypelibGuts. */
+
+#include "xptiprivate.h"
+#include "mozilla/XPTInterfaceInfoManager.h"
+
+using namespace mozilla;
+
+// Ensure through static analysis that xptiTypelibGuts won't have a vtable.
+template <class T>
+class MOZ_NEEDS_NO_VTABLE_TYPE CheckNoVTable
+{
+};
+CheckNoVTable<xptiTypelibGuts> gChecker;
+
+// static
+xptiTypelibGuts*
+xptiTypelibGuts::Create(XPTHeader* aHeader)
+{
+    NS_ASSERTION(aHeader, "bad param");
+    size_t n = sizeof(xptiTypelibGuts) +
+               sizeof(xptiInterfaceEntry*) * (aHeader->num_interfaces - 1);
+    void* place = XPT_CALLOC8(gXPTIStructArena, n);
+    if (!place)
+        return nullptr;
+    return new(place) xptiTypelibGuts(aHeader);
+}
+
+xptiInterfaceEntry*
+xptiTypelibGuts::GetEntryAt(uint16_t i)
+{
+    static const nsID zeroIID =
+        { 0x0, 0x0, 0x0, { 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0 } };
+
+    NS_ASSERTION(mHeader, "bad state");
+    NS_ASSERTION(i < GetEntryCount(), "bad index");
+
+    xptiInterfaceEntry* r = mEntryArray[i];
+    if (r)
+        return r;
+
+    XPTInterfaceDirectoryEntry* iface = mHeader->interface_directory + i;
+
+    XPTInterfaceInfoManager::xptiWorkingSet& set =
+        XPTInterfaceInfoManager::GetSingleton()->mWorkingSet;
+
+    {
+        ReentrantMonitorAutoEnter monitor(set.mTableReentrantMonitor);
+        if (iface->iid.Equals(zeroIID))
+            r = set.mNameTable.Get(iface->name);
+        else
+            r = set.mIIDTable.Get(iface->iid);
+    }
+
+    if (r)
+        SetEntryAt(i, r);
+
+    return r;
+}
+
+const char*
+xptiTypelibGuts::GetEntryNameAt(uint16_t i)
+{
+    NS_ASSERTION(mHeader, "bad state");
+    NS_ASSERTION(i < GetEntryCount(), "bad index");
+
+    XPTInterfaceDirectoryEntry* iface = mHeader->interface_directory + i;
+
+    return iface->name;
+}
diff --git a/xpcom/reflect/xptinfo/xptiWorkingSet.cpp b/xpcom/reflect/xptinfo/xptiWorkingSet.cpp
new file mode 100644
index 000000000..10f81a4b2
--- /dev/null
+++ b/xpcom/reflect/xptinfo/xptiWorkingSet.cpp
@@ -0,0 +1,53 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* vim: set ts=8 sts=4 et sw=4 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implementation of xptiWorkingSet. */
+
+#include "mozilla/XPTInterfaceInfoManager.h"
+
+#include "xptiprivate.h"
+#include "nsString.h"
+
+using namespace mozilla;
+
+static const size_t XPTI_ARENA8_BLOCK_SIZE = 16 * 1024;
+static const size_t XPTI_ARENA1_BLOCK_SIZE =  8 * 1024;
+
+static const uint32_t XPTI_HASHTABLE_LENGTH = 1024;
+
+XPTInterfaceInfoManager::xptiWorkingSet::xptiWorkingSet()
+    : mTableReentrantMonitor("xptiWorkingSet::mTableReentrantMonitor")
+    , mIIDTable(XPTI_HASHTABLE_LENGTH)
+    , mNameTable(XPTI_HASHTABLE_LENGTH)
+{
+    MOZ_COUNT_CTOR(xptiWorkingSet);
+
+    gXPTIStructArena = XPT_NewArena(XPTI_ARENA8_BLOCK_SIZE,
+                                    XPTI_ARENA1_BLOCK_SIZE);
+}
+
+void
+XPTInterfaceInfoManager::xptiWorkingSet::InvalidateInterfaceInfos()
+{
+    ReentrantMonitorAutoEnter monitor(mTableReentrantMonitor);
+    for (auto iter = mNameTable.Iter(); !iter.Done(); iter.Next()) {
+        xptiInterfaceEntry* entry = iter.UserData();
+        entry->LockedInvalidateInterfaceInfo();
+    }
+}
+
+XPTInterfaceInfoManager::xptiWorkingSet::~xptiWorkingSet()
+{
+    MOZ_COUNT_DTOR(xptiWorkingSet);
+
+    // Only destroy the arena if we're doing leak stats. Why waste shutdown
+    // time touching pages if we don't have to?
+#ifdef NS_FREE_PERMANENT_DATA
+    XPT_DestroyArena(gXPTIStructArena);
+#endif
+}
+
+XPTArena* gXPTIStructArena;
diff --git a/xpcom/reflect/xptinfo/xptinfo.h b/xpcom/reflect/xptinfo/xptinfo.h
new file mode 100644
index 000000000..1207a42bb
--- /dev/null
+++ b/xpcom/reflect/xptinfo/xptinfo.h
@@ -0,0 +1,236 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* XPTI_PUBLIC_API and XPTI_GetInterfaceInfoManager declarations. */
+
+#ifndef xptiinfo_h___
+#define xptiinfo_h___
+
+#include "nscore.h"
+#include "xpt_struct.h"
+
+// Flyweight wrapper classes for xpt_struct.h structs.
+// Everything here is dependent upon - and sensitive to changes in -
+// xpcom/typelib/xpt/xpt_struct.h!
+
+class nsXPTType : public XPTTypeDescriptorPrefix
+{
+// NO DATA - this a flyweight wrapper
+public:
+    nsXPTType()
+        {}    // random contents
+    MOZ_IMPLICIT nsXPTType(const XPTTypeDescriptorPrefix& prefix)
+        {*(XPTTypeDescriptorPrefix*)this = prefix;}
+
+    MOZ_IMPLICIT nsXPTType(const uint8_t& prefix)
+        {*(uint8_t*)this = prefix;}
+
+    nsXPTType& operator=(uint8_t val)
+        {flags = val; return *this;}
+
+    nsXPTType& operator=(const nsXPTType& other)
+        {flags = other.flags; return *this;}
+
+    operator uint8_t() const
+        {return flags;}
+
+    // 'Arithmetic' here roughly means that the value is self-contained and
+    // doesn't depend on anything else in memory (ie: not a pointer, not an
+    // XPCOM object, not a jsval, etc).
+    //
+    // Supposedly this terminology comes from Harbison/Steele, but it's still
+    // a rather crappy name. We'd change it if it wasn't used all over the
+    // place in xptcall. :-(
+    bool IsArithmetic() const
+        {return flags <= T_WCHAR;}
+
+    // We used to abuse 'pointer' flag bit in typelib format quite extensively.
+    // We've gotten rid of most of the cases, but there's still a fair amount
+    // of refactoring to be done in XPCWrappedJSClass before we can safely stop
+    // asking about this. In the mean time, we've got a temporary version of
+    // IsPointer() that should be equivalent to what's in the typelib.
+    bool deprecated_IsPointer() const
+        {return !IsArithmetic() && TagPart() != T_JSVAL;}
+
+    bool IsInterfacePointer() const
+        {  switch (TagPart()) {
+             default:
+               return false;
+             case T_INTERFACE:
+             case T_INTERFACE_IS:
+               return true;
+           }
+        }
+
+    bool IsArray() const
+        {return TagPart() == T_ARRAY;}
+
+    // 'Dependent' means that params of this type are dependent upon other
+    // params. e.g. an T_INTERFACE_IS is dependent upon some other param at
+    // runtime to say what the interface type of this param really is.
+    bool IsDependent() const
+        {  switch (TagPart()) {
+             default:
+               return false;
+             case T_INTERFACE_IS:
+             case TD_ARRAY:
+             case T_PSTRING_SIZE_IS:
+             case T_PWSTRING_SIZE_IS:
+               return true;
+           }
+        }
+
+    uint8_t TagPart() const
+        {return (uint8_t) (flags & XPT_TDP_TAGMASK);}
+
+    enum
+    {
+        T_I8                = TD_INT8             ,
+        T_I16               = TD_INT16            ,
+        T_I32               = TD_INT32            ,
+        T_I64               = TD_INT64            ,
+        T_U8                = TD_UINT8            ,
+        T_U16               = TD_UINT16           ,
+        T_U32               = TD_UINT32           ,
+        T_U64               = TD_UINT64           ,
+        T_FLOAT             = TD_FLOAT            ,
+        T_DOUBLE            = TD_DOUBLE           ,
+        T_BOOL              = TD_BOOL             ,
+        T_CHAR              = TD_CHAR             ,
+        T_WCHAR             = TD_WCHAR            ,
+        T_VOID              = TD_VOID             ,
+        T_IID               = TD_PNSIID           ,
+        T_DOMSTRING         = TD_DOMSTRING        ,
+        T_CHAR_STR          = TD_PSTRING          ,
+        T_WCHAR_STR         = TD_PWSTRING         ,
+        T_INTERFACE         = TD_INTERFACE_TYPE   ,
+        T_INTERFACE_IS      = TD_INTERFACE_IS_TYPE,
+        T_ARRAY             = TD_ARRAY            ,
+        T_PSTRING_SIZE_IS   = TD_PSTRING_SIZE_IS  ,
+        T_PWSTRING_SIZE_IS  = TD_PWSTRING_SIZE_IS ,
+        T_UTF8STRING        = TD_UTF8STRING       ,
+        T_CSTRING           = TD_CSTRING          ,
+        T_ASTRING           = TD_ASTRING          ,
+        T_JSVAL             = TD_JSVAL
+    };
+// NO DATA - this a flyweight wrapper
+};
+
+class nsXPTParamInfo : public XPTParamDescriptor
+{
+// NO DATA - this a flyweight wrapper
+public:
+    MOZ_IMPLICIT nsXPTParamInfo(const XPTParamDescriptor& desc)
+        {*(XPTParamDescriptor*)this = desc;}
+
+
+    bool IsIn()  const    {return 0 != (XPT_PD_IS_IN(flags));}
+    bool IsOut() const    {return 0 != (XPT_PD_IS_OUT(flags));}
+    bool IsRetval() const {return 0 != (XPT_PD_IS_RETVAL(flags));}
+    bool IsShared() const {return 0 != (XPT_PD_IS_SHARED(flags));}
+
+    // Dipper types are one of the more inscrutable aspects of xpidl. In a
+    // nutshell, dippers are empty container objects, created and passed by
+    // the caller, and filled by the callee. The callee receives a fully-
+    // formed object, and thus does not have to construct anything. But
+    // the object is functionally empty, and the callee is responsible for
+    // putting something useful inside of it.
+    //
+    // XPIDL decides which types to make dippers. The list of these types
+    // is given in the isDipperType() function in typelib.py, and is currently
+    // limited to 4 string types.
+    //
+    // When a dipper type is declared as an 'out' parameter, xpidl internally
+    // converts it to an 'in', and sets the XPT_PD_DIPPER flag on it. For this
+    // reason, dipper types are sometimes referred to as 'out parameters
+    // masquerading as in'. The burden of maintaining this illusion falls mostly
+    // on XPConnect, which creates the empty containers, and harvest the results
+    // after the call.
+    bool IsDipper() const {return 0 != (XPT_PD_IS_DIPPER(flags));}
+    bool IsOptional() const {return 0 != (XPT_PD_IS_OPTIONAL(flags));}
+    const nsXPTType GetType() const {return type.prefix;}
+
+    bool IsStringClass() const {
+      switch (GetType().TagPart()) {
+        case nsXPTType::T_ASTRING:
+        case nsXPTType::T_DOMSTRING:
+        case nsXPTType::T_UTF8STRING:
+        case nsXPTType::T_CSTRING:
+          return true;
+        default:
+          return false;
+      }
+    }
+
+    // Whether this parameter is passed indirectly on the stack. This mainly
+    // applies to out/inout params, but we use it unconditionally for certain
+    // types.
+    bool IsIndirect() const {return IsOut() ||
+                               GetType().TagPart() == nsXPTType::T_JSVAL;}
+
+    // NOTE: other activities on types are done via methods on nsIInterfaceInfo
+
+private:
+    nsXPTParamInfo();   // no implementation
+// NO DATA - this a flyweight wrapper
+};
+
+class nsXPTMethodInfo : public XPTMethodDescriptor
+{
+// NO DATA - this a flyweight wrapper
+public:
+    MOZ_IMPLICIT nsXPTMethodInfo(const XPTMethodDescriptor& desc)
+        {*(XPTMethodDescriptor*)this = desc;}
+
+    bool IsGetter()      const {return 0 != (XPT_MD_IS_GETTER(flags) );}
+    bool IsSetter()      const {return 0 != (XPT_MD_IS_SETTER(flags) );}
+    bool IsNotXPCOM()    const {return 0 != (XPT_MD_IS_NOTXPCOM(flags));}
+    bool IsHidden()      const {return 0 != (XPT_MD_IS_HIDDEN(flags) );}
+    bool WantsOptArgc()  const {return 0 != (XPT_MD_WANTS_OPT_ARGC(flags));}
+    bool WantsContext()  const {return 0 != (XPT_MD_WANTS_CONTEXT(flags));}
+    const char* GetName()  const {return name;}
+    uint8_t GetParamCount()  const {return num_args;}
+    /* idx was index before I got _sick_ of the warnings on Unix, sorry jband */
+    const nsXPTParamInfo GetParam(uint8_t idx) const
+        {
+            NS_PRECONDITION(idx < GetParamCount(),"bad arg");
+            return params[idx];
+        }
+    const nsXPTParamInfo GetResult() const
+        {return result;}
+private:
+    nsXPTMethodInfo();  // no implementation
+// NO DATA - this a flyweight wrapper
+};
+
+
+// forward declaration
+struct nsXPTCMiniVariant;
+
+class nsXPTConstant : public XPTConstDescriptor
+{
+// NO DATA - this a flyweight wrapper
+public:
+    MOZ_IMPLICIT nsXPTConstant(const XPTConstDescriptor& desc)
+        {*(XPTConstDescriptor*)this = desc;}
+
+    const char* GetName() const
+        {return name;}
+
+    const nsXPTType GetType() const
+        {return type.prefix;}
+
+    // XXX this is ugly. But sometimes you gotta do what you gotta do.
+    // A reinterpret_cast won't do the trick here. And this plain C cast
+    // works correctly and is safe enough.
+    // See http://bugzilla.mozilla.org/show_bug.cgi?id=49641
+    const nsXPTCMiniVariant* GetValue() const
+        {return (nsXPTCMiniVariant*) &value;}
+private:
+    nsXPTConstant();    // no implementation
+// NO DATA - this a flyweight wrapper
+};
+
+#endif /* xptiinfo_h___ */
diff --git a/xpcom/reflect/xptinfo/xptiprivate.h b/xpcom/reflect/xptinfo/xptiprivate.h
new file mode 100644
index 000000000..c32ef9c77
--- /dev/null
+++ b/xpcom/reflect/xptinfo/xptiprivate.h
@@ -0,0 +1,394 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Library-private header for Interface Info system. */
+
+#ifndef xptiprivate_h___
+#define xptiprivate_h___
+
+#include "nscore.h"
+#include <new>
+#include "nsISupports.h"
+
+// this after nsISupports, to pick up IID
+// so that xpt stuff doesn't try to define it itself...
+#include "xpt_struct.h"
+#include "xpt_xdr.h"
+
+#include "nsIInterfaceInfo.h"
+#include "nsIInterfaceInfoManager.h"
+#include "xptinfo.h"
+#include "ShimInterfaceInfo.h"
+
+#include "nsIServiceManager.h"
+#include "nsIFile.h"
+#include "nsIDirectoryService.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsAppDirectoryServiceDefs.h"
+#include "nsIWeakReference.h"
+
+#include "mozilla/ReentrantMonitor.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/Attributes.h"
+
+#include "js/TypeDecls.h"
+
+#include "nsCRT.h"
+#include "nsMemory.h"
+
+#include "nsCOMArray.h"
+#include "nsQuickSort.h"
+
+#include "nsXPIDLString.h"
+
+#include "nsIInputStream.h"
+
+#include "nsHashKeys.h"
+#include "nsDataHashtable.h"
+#include "plstr.h"
+#include "prprf.h"
+#include "prio.h"
+#include "prtime.h"
+#include "prenv.h"
+
+#include <stdio.h>
+#include <stdarg.h>
+
+/***************************************************************************/
+
+#if 0 && defined(DEBUG_jband)
+#define LOG_RESOLVE(x) printf x
+#define LOG_LOAD(x)    printf x
+#define LOG_AUTOREG(x) do{printf x; xptiInterfaceInfoManager::WriteToLog x;}while(0)
+#else
+#define LOG_RESOLVE(x) ((void)0)
+#define LOG_LOAD(x)    ((void)0)
+#define LOG_AUTOREG(x) ((void)0)
+#endif
+
+#if 1 && defined(DEBUG_jband)
+#define SHOW_INFO_COUNT_STATS
+#endif
+
+/***************************************************************************/
+
+class xptiInterfaceInfo;
+class xptiInterfaceEntry;
+class xptiTypelibGuts;
+
+extern XPTArena* gXPTIStructArena;
+
+/***************************************************************************/
+
+/***************************************************************************/
+
+// No virtuals.
+// These are always constructed in the struct arena using placement new.
+// dtor need not be called.
+
+class xptiTypelibGuts
+{
+public:
+    static xptiTypelibGuts* Create(XPTHeader* aHeader);
+
+    XPTHeader*          GetHeader()           {return mHeader;}
+    uint16_t            GetEntryCount() const {return mHeader->num_interfaces;}
+
+    void                SetEntryAt(uint16_t i, xptiInterfaceEntry* ptr)
+    {
+        NS_ASSERTION(mHeader,"bad state!");
+        NS_ASSERTION(i < GetEntryCount(),"bad param!");
+        mEntryArray[i] = ptr;
+    }
+
+    xptiInterfaceEntry* GetEntryAt(uint16_t i);
+    const char* GetEntryNameAt(uint16_t i);
+
+private:
+    explicit xptiTypelibGuts(XPTHeader* aHeader)
+        : mHeader(aHeader)
+    { }
+    ~xptiTypelibGuts();
+
+private:
+    XPTHeader*           mHeader;        // hold pointer into arena
+    xptiInterfaceEntry*  mEntryArray[1]; // Always last. Sized to fit.
+};
+
+/***************************************************************************/
+
+/***************************************************************************/
+
+// This class exists to help xptiInterfaceInfo store a 4-state (2 bit) value
+// and a set of bitflags in one 8bit value. See below.
+
+class xptiInfoFlags
+{
+    enum {STATE_MASK = 3};
+public:
+    explicit xptiInfoFlags(uint8_t n) : mData(n) {}
+    xptiInfoFlags(const xptiInfoFlags& r) : mData(r.mData) {}
+
+    static uint8_t GetStateMask()
+        {return uint8_t(STATE_MASK);}
+
+    void Clear()
+        {mData = 0;}
+
+    uint8_t GetData() const
+        {return mData;}
+
+    uint8_t GetState() const
+        {return mData & GetStateMask();}
+
+    void SetState(uint8_t state)
+        {mData &= ~GetStateMask(); mData |= state;}
+
+    void SetFlagBit(uint8_t flag, bool on)
+        {if(on)
+            mData |= ~GetStateMask() & flag;
+         else
+            mData &= GetStateMask() | ~flag;}
+
+    bool GetFlagBit(uint8_t flag) const
+        {return (mData & flag) ? true : false;}
+
+private:
+    uint8_t mData;
+};
+
+/****************************************************/
+
+// No virtual methods.
+// We always create in the struct arena and construct using "placement new".
+// No members need dtor calls.
+
+class xptiInterfaceEntry
+{
+public:
+    static xptiInterfaceEntry* Create(const char* name,
+                                      const nsID& iid,
+                                      XPTInterfaceDescriptor* aDescriptor,
+                                      xptiTypelibGuts* aTypelib);
+
+    enum {
+        PARTIALLY_RESOLVED    = 1,
+        FULLY_RESOLVED        = 2,
+        RESOLVE_FAILED        = 3
+    };
+
+    // Additional bit flags...
+    enum {SCRIPTABLE = 4, BUILTINCLASS = 8, HASNOTXPCOM = 16,
+          MAIN_PROCESS_SCRIPTABLE_ONLY = 32};
+
+    uint8_t GetResolveState() const {return mFlags.GetState();}
+
+    bool IsFullyResolved() const
+        {return GetResolveState() == (uint8_t) FULLY_RESOLVED;}
+
+    void SetScriptableFlag(bool on)
+                {mFlags.SetFlagBit(uint8_t(SCRIPTABLE),on);}
+    bool GetScriptableFlag() const
+                {return mFlags.GetFlagBit(uint8_t(SCRIPTABLE));}
+    void SetBuiltinClassFlag(bool on)
+                {mFlags.SetFlagBit(uint8_t(BUILTINCLASS),on);}
+    bool GetBuiltinClassFlag() const
+                {return mFlags.GetFlagBit(uint8_t(BUILTINCLASS));}
+    void SetMainProcessScriptableOnlyFlag(bool on)
+                {mFlags.SetFlagBit(uint8_t(MAIN_PROCESS_SCRIPTABLE_ONLY),on);}
+    bool GetMainProcessScriptableOnlyFlag() const
+                {return mFlags.GetFlagBit(uint8_t(MAIN_PROCESS_SCRIPTABLE_ONLY));}
+
+
+    // AddRef/Release are special and are not considered for the NOTXPCOM flag.
+    void SetHasNotXPCOMFlag()
+    {
+        mFlags.SetFlagBit(HASNOTXPCOM, true);
+    }
+    bool GetHasNotXPCOMFlag() const
+    {
+        return mFlags.GetFlagBit(HASNOTXPCOM);
+    }
+
+    const nsID* GetTheIID()  const {return &mIID;}
+    const char* GetTheName() const {return mName;}
+
+    bool EnsureResolved()
+        {return IsFullyResolved() ? true : Resolve();}
+
+    already_AddRefed<xptiInterfaceInfo> InterfaceInfo();
+    bool     InterfaceInfoEquals(const xptiInterfaceInfo* info) const
+        {return info == mInfo;}
+
+    void     LockedInvalidateInterfaceInfo();
+    void     LockedInterfaceInfoDeathNotification() {mInfo = nullptr;}
+
+    xptiInterfaceEntry* Parent() const {
+        NS_ASSERTION(IsFullyResolved(), "Parent() called while not resolved?");
+        return mParent;
+    }
+
+    const nsID& IID() const { return mIID; }
+
+    //////////////////////
+    // These non-virtual methods handle the delegated nsIInterfaceInfo methods.
+
+    nsresult GetName(char * *aName);
+    nsresult GetIID(nsIID * *aIID);
+    nsresult IsScriptable(bool *_retval);
+    nsresult IsBuiltinClass(bool *_retval) {
+        *_retval = GetBuiltinClassFlag();
+        return NS_OK;
+    }
+    nsresult IsMainProcessScriptableOnly(bool *_retval) {
+        *_retval = GetMainProcessScriptableOnlyFlag();
+        return NS_OK;
+    }
+    // Except this one.
+    //nsresult GetParent(nsIInterfaceInfo * *aParent);
+    nsresult GetMethodCount(uint16_t *aMethodCount);
+    nsresult GetConstantCount(uint16_t *aConstantCount);
+    nsresult GetMethodInfo(uint16_t index, const nsXPTMethodInfo * *info);
+    nsresult GetMethodInfoForName(const char *methodName, uint16_t *index, const nsXPTMethodInfo * *info);
+    nsresult GetConstant(uint16_t index, JS::MutableHandleValue, char** constant);
+    nsresult GetInfoForParam(uint16_t methodIndex, const nsXPTParamInfo * param, nsIInterfaceInfo **_retval);
+    nsresult GetIIDForParam(uint16_t methodIndex, const nsXPTParamInfo * param, nsIID * *_retval);
+    nsresult GetTypeForParam(uint16_t methodIndex, const nsXPTParamInfo * param, uint16_t dimension, nsXPTType *_retval);
+    nsresult GetSizeIsArgNumberForParam(uint16_t methodIndex, const nsXPTParamInfo * param, uint16_t dimension, uint8_t *_retval);
+    nsresult GetInterfaceIsArgNumberForParam(uint16_t methodIndex, const nsXPTParamInfo * param, uint8_t *_retval);
+    nsresult IsIID(const nsIID * IID, bool *_retval);
+    nsresult GetNameShared(const char **name);
+    nsresult GetIIDShared(const nsIID * *iid);
+    nsresult IsFunction(bool *_retval);
+    nsresult HasAncestor(const nsIID * iid, bool *_retval);
+    nsresult GetIIDForParamNoAlloc(uint16_t methodIndex, const nsXPTParamInfo * param, nsIID *iid);
+
+private:
+    xptiInterfaceEntry(const char* name,
+                       size_t nameLength,
+                       const nsID& iid,
+                       XPTInterfaceDescriptor* aDescriptor,
+                       xptiTypelibGuts* aTypelib);
+    ~xptiInterfaceEntry();
+
+    void SetResolvedState(int state)
+        {mFlags.SetState(uint8_t(state));}
+
+    bool Resolve();
+
+    // We only call these "*Locked" variants after locking. This is done to
+    // allow reentrace as files are loaded and various interfaces resolved
+    // without having to worry about the locked state.
+
+    bool EnsureResolvedLocked()
+        {return IsFullyResolved() ? true : ResolveLocked();}
+    bool ResolveLocked();
+
+    // private helpers
+
+    nsresult GetEntryForParam(uint16_t methodIndex,
+                              const nsXPTParamInfo * param,
+                              xptiInterfaceEntry** entry);
+
+    nsresult GetTypeInArray(const nsXPTParamInfo* param,
+                            uint16_t dimension,
+                            const XPTTypeDescriptor** type);
+
+    nsresult GetInterfaceIndexForParam(uint16_t methodIndex,
+                                       const nsXPTParamInfo* param,
+                                       uint16_t* interfaceIndex);
+
+    already_AddRefed<ShimInterfaceInfo>
+    GetShimForParam(uint16_t methodIndex, const nsXPTParamInfo* param);
+
+private:
+    nsID                    mIID;
+    XPTInterfaceDescriptor* mDescriptor;
+
+    xptiTypelibGuts* mTypelib;
+
+    xptiInterfaceEntry*     mParent;      // Valid only when fully resolved
+
+    xptiInterfaceInfo* MOZ_UNSAFE_REF("The safety of this pointer is ensured "
+                                      "by the semantics of xptiWorkingSet.")
+                            mInfo;        // May come and go.
+
+    uint16_t mMethodBaseIndex;
+    uint16_t mConstantBaseIndex;
+
+    xptiInfoFlags           mFlags;
+
+    char                    mName[1];     // Always last. Sized to fit.
+};
+
+class xptiInterfaceInfo final : public nsIInterfaceInfo
+{
+public:
+    NS_DECL_THREADSAFE_ISUPPORTS
+
+    // Use delegation to implement (most!) of nsIInterfaceInfo.
+    NS_IMETHOD GetName(char * *aName) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->GetName(aName); }
+    NS_IMETHOD GetInterfaceIID(nsIID * *aIID) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->GetIID(aIID); }
+    NS_IMETHOD IsScriptable(bool *_retval) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->IsScriptable(_retval); }
+    NS_IMETHOD IsBuiltinClass(bool *_retval) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->IsBuiltinClass(_retval); }
+    NS_IMETHOD IsMainProcessScriptableOnly(bool *_retval) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->IsMainProcessScriptableOnly(_retval); }
+    // Except this one.
+    NS_IMETHOD GetParent(nsIInterfaceInfo * *aParent) override
+    {
+        if(!EnsureResolved() || !EnsureParent())
+            return NS_ERROR_UNEXPECTED;
+        NS_IF_ADDREF(*aParent = mParent);
+        return NS_OK;
+    }
+    NS_IMETHOD GetMethodCount(uint16_t *aMethodCount) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->GetMethodCount(aMethodCount); }
+    NS_IMETHOD GetConstantCount(uint16_t *aConstantCount) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->GetConstantCount(aConstantCount); }
+    NS_IMETHOD GetMethodInfo(uint16_t index, const nsXPTMethodInfo * *info) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->GetMethodInfo(index, info); }
+    NS_IMETHOD GetMethodInfoForName(const char *methodName, uint16_t *index, const nsXPTMethodInfo * *info) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->GetMethodInfoForName(methodName, index, info); }
+    NS_IMETHOD GetConstant(uint16_t index, JS::MutableHandleValue constant, char** name) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->GetConstant(index, constant, name); }
+    NS_IMETHOD GetInfoForParam(uint16_t methodIndex, const nsXPTParamInfo * param, nsIInterfaceInfo **_retval) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->GetInfoForParam(methodIndex, param, _retval); }
+    NS_IMETHOD GetIIDForParam(uint16_t methodIndex, const nsXPTParamInfo * param, nsIID * *_retval) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->GetIIDForParam(methodIndex, param, _retval); }
+    NS_IMETHOD GetTypeForParam(uint16_t methodIndex, const nsXPTParamInfo * param, uint16_t dimension, nsXPTType *_retval) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->GetTypeForParam(methodIndex, param, dimension, _retval); }
+    NS_IMETHOD GetSizeIsArgNumberForParam(uint16_t methodIndex, const nsXPTParamInfo * param, uint16_t dimension, uint8_t *_retval) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->GetSizeIsArgNumberForParam(methodIndex, param, dimension, _retval); }
+    NS_IMETHOD GetInterfaceIsArgNumberForParam(uint16_t methodIndex, const nsXPTParamInfo * param, uint8_t *_retval) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->GetInterfaceIsArgNumberForParam(methodIndex, param, _retval); }
+    NS_IMETHOD IsIID(const nsIID * IID, bool *_retval) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->IsIID(IID, _retval); }
+    NS_IMETHOD GetNameShared(const char **name) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->GetNameShared(name); }
+    NS_IMETHOD GetIIDShared(const nsIID * *iid) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->GetIIDShared(iid); }
+    NS_IMETHOD IsFunction(bool *_retval) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->IsFunction(_retval); }
+    NS_IMETHOD HasAncestor(const nsIID * iid, bool *_retval) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->HasAncestor(iid, _retval); }
+    NS_IMETHOD GetIIDForParamNoAlloc(uint16_t methodIndex, const nsXPTParamInfo * param, nsIID *iid) override { return !mEntry ? NS_ERROR_UNEXPECTED : mEntry->GetIIDForParamNoAlloc(methodIndex, param, iid); }
+
+public:
+    explicit xptiInterfaceInfo(xptiInterfaceEntry* entry);
+
+    void Invalidate();
+
+private:
+
+    ~xptiInterfaceInfo();
+
+    // Note that mParent might still end up as nullptr if we don't have one.
+    bool EnsureParent()
+    {
+        NS_ASSERTION(mEntry && mEntry->IsFullyResolved(), "bad EnsureParent call");
+        return mParent || !mEntry->Parent() || BuildParent();
+    }
+
+    bool EnsureResolved()
+    {
+        return mEntry && mEntry->EnsureResolved();
+    }
+
+    bool BuildParent();
+
+    xptiInterfaceInfo();  // not implemented
+
+private:
+    xptiInterfaceEntry* mEntry;
+    RefPtr<xptiInterfaceInfo> mParent;
+};
+
+/***************************************************************************/
+
+#endif /* xptiprivate_h___ */
diff --git a/xpcom/rust/nsstring/Cargo.toml b/xpcom/rust/nsstring/Cargo.toml
new file mode 100644
index 000000000..d86a1ad26
--- /dev/null
+++ b/xpcom/rust/nsstring/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "nsstring"
+version = "0.1.0"
+authors = ["nobody@mozilla.com"]
+license = "MPL-2.0"
+description = "Rust bindings to xpcom string types"
+
+[dependencies]
diff --git a/xpcom/rust/nsstring/gtest/Cargo.toml b/xpcom/rust/nsstring/gtest/Cargo.toml
new file mode 100644
index 000000000..44897ec98
--- /dev/null
+++ b/xpcom/rust/nsstring/gtest/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "nsstring-gtest"
+version = "0.1.0"
+authors = ["nobody@mozilla.com"]
+license = "MPL-2.0"
+description = "Tests for rust bindings to xpcom string types"
+
+[dependencies]
+nsstring = { path = "../" }
+
+[lib]
+path = "test.rs"
diff --git a/xpcom/rust/nsstring/gtest/Test.cpp b/xpcom/rust/nsstring/gtest/Test.cpp
new file mode 100644
index 000000000..93d2ee1d7
--- /dev/null
+++ b/xpcom/rust/nsstring/gtest/Test.cpp
@@ -0,0 +1,131 @@
+#include "gtest/gtest.h"
+#include <stdint.h>
+#include "nsString.h"
+
+extern "C" {
+  // This function is called by the rust code in test.rs if a non-fatal test
+  // failure occurs.
+  void GTest_ExpectFailure(const char* aMessage) {
+    EXPECT_STREQ(aMessage, "");
+  }
+}
+
+#define SIZE_ALIGN_CHECK(Clazz)                                         \
+  extern "C" void Rust_Test_ReprSizeAlign_##Clazz(size_t* size, size_t* align); \
+  TEST(RustNsString, ReprSizeAlign_##Clazz) {                           \
+    size_t size, align;                                                 \
+    Rust_Test_ReprSizeAlign_##Clazz(&size, &align);                     \
+    EXPECT_EQ(size, sizeof(Clazz));                                     \
+    EXPECT_EQ(align, alignof(Clazz));                                   \
+  }
+
+SIZE_ALIGN_CHECK(nsString)
+SIZE_ALIGN_CHECK(nsCString)
+SIZE_ALIGN_CHECK(nsFixedString)
+SIZE_ALIGN_CHECK(nsFixedCString)
+
+#define MEMBER_CHECK(Clazz, Member)                                     \
+  extern "C" void Rust_Test_Member_##Clazz##_##Member(size_t* size,     \
+                                                      size_t* align,    \
+                                                      size_t* offset);  \
+  TEST(RustNsString, ReprMember_##Clazz##_##Member) {                   \
+    class Hack : public Clazz {                                         \
+    public:                                                             \
+      static void RunTest() {                                           \
+        size_t size, align, offset;                                     \
+        Rust_Test_Member_##Clazz##_##Member(&size, &align, &offset);    \
+        EXPECT_EQ(size, sizeof(mozilla::DeclVal<Hack>().Member));       \
+        EXPECT_EQ(size, alignof(decltype(mozilla::DeclVal<Hack>().Member))); \
+        EXPECT_EQ(offset, offsetof(Hack, Member));                      \
+      }                                                                 \
+    };                                                                  \
+    static_assert(sizeof(Clazz) == sizeof(Hack), "Hack matches class"); \
+    Hack::RunTest();                                                    \
+  }
+
+MEMBER_CHECK(nsString, mData)
+MEMBER_CHECK(nsString, mLength)
+MEMBER_CHECK(nsString, mFlags)
+MEMBER_CHECK(nsCString, mData)
+MEMBER_CHECK(nsCString, mLength)
+MEMBER_CHECK(nsCString, mFlags)
+MEMBER_CHECK(nsFixedString, mFixedCapacity)
+MEMBER_CHECK(nsFixedString, mFixedBuf)
+MEMBER_CHECK(nsFixedCString, mFixedCapacity)
+MEMBER_CHECK(nsFixedCString, mFixedBuf)
+
+extern "C" void Rust_Test_NsStringFlags(uint32_t* f_none,
+                                        uint32_t* f_terminated,
+                                        uint32_t* f_voided,
+                                        uint32_t* f_shared,
+                                        uint32_t* f_owned,
+                                        uint32_t* f_fixed,
+                                        uint32_t* f_literal,
+                                        uint32_t* f_class_fixed);
+TEST(RustNsString, NsStringFlags) {
+  uint32_t f_none, f_terminated, f_voided, f_shared, f_owned, f_fixed, f_literal, f_class_fixed;
+  Rust_Test_NsStringFlags(&f_none, &f_terminated,
+                          &f_voided, &f_shared,
+                          &f_owned, &f_fixed,
+                          &f_literal, &f_class_fixed);
+  EXPECT_EQ(f_none, nsAString::F_NONE);
+  EXPECT_EQ(f_none, nsACString::F_NONE);
+  EXPECT_EQ(f_terminated, nsAString::F_TERMINATED);
+  EXPECT_EQ(f_terminated, nsACString::F_TERMINATED);
+  EXPECT_EQ(f_voided, nsAString::F_VOIDED);
+  EXPECT_EQ(f_voided, nsACString::F_VOIDED);
+  EXPECT_EQ(f_shared, nsAString::F_SHARED);
+  EXPECT_EQ(f_shared, nsACString::F_SHARED);
+  EXPECT_EQ(f_owned, nsAString::F_OWNED);
+  EXPECT_EQ(f_owned, nsACString::F_OWNED);
+  EXPECT_EQ(f_fixed, nsAString::F_FIXED);
+  EXPECT_EQ(f_fixed, nsACString::F_FIXED);
+  EXPECT_EQ(f_literal, nsAString::F_LITERAL);
+  EXPECT_EQ(f_literal, nsACString::F_LITERAL);
+  EXPECT_EQ(f_class_fixed, nsAString::F_CLASS_FIXED);
+  EXPECT_EQ(f_class_fixed, nsACString::F_CLASS_FIXED);
+}
+
+extern "C" void Rust_StringFromCpp(const nsACString* aCStr, const nsAString* aStr);
+TEST(RustNsString, StringFromCpp) {
+  nsAutoCString foo;
+  foo.AssignASCII("Hello, World!");
+
+  nsAutoString bar;
+  bar.AssignASCII("Hello, World!");
+
+  Rust_StringFromCpp(&foo, &bar);
+}
+
+extern "C" void Rust_AssignFromRust(nsACString* aCStr, nsAString* aStr);
+TEST(RustNsString, AssignFromRust) {
+  nsAutoCString cs;
+  nsAutoString s;
+  Rust_AssignFromRust(&cs, &s);
+  EXPECT_TRUE(cs.EqualsASCII("Hello, World!"));
+  EXPECT_TRUE(s.EqualsASCII("Hello, World!"));
+}
+
+extern "C" {
+  void Cpp_AssignFromCpp(nsACString* aCStr, nsAString* aStr) {
+    aCStr->AssignASCII("Hello, World!");
+    aStr->AssignASCII("Hello, World!");
+  }
+}
+extern "C" void Rust_AssignFromCpp();
+TEST(RustNsString, AssignFromCpp) {
+  Rust_AssignFromCpp();
+}
+extern "C" void Rust_FixedAssignFromCpp();
+TEST(RustNsString, FixedAssignFromCpp) {
+  Rust_FixedAssignFromCpp();
+}
+extern "C" void Rust_AutoAssignFromCpp();
+TEST(RustNsString, AutoAssignFromCpp) {
+  Rust_AutoAssignFromCpp();
+}
+
+extern "C" void Rust_StringWrite();
+TEST(RustNsString, StringWrite) {
+  Rust_StringWrite();
+}
diff --git a/xpcom/rust/nsstring/gtest/moz.build b/xpcom/rust/nsstring/gtest/moz.build
new file mode 100644
index 000000000..5bed9e57e
--- /dev/null
+++ b/xpcom/rust/nsstring/gtest/moz.build
@@ -0,0 +1,12 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+if CONFIG['MOZ_RUST']:
+    UNIFIED_SOURCES += [
+        'Test.cpp'
+    ]
+
+FINAL_LIBRARY = 'xul-gtest'
diff --git a/xpcom/rust/nsstring/gtest/test.rs b/xpcom/rust/nsstring/gtest/test.rs
new file mode 100644
index 000000000..2968a1be7
--- /dev/null
+++ b/xpcom/rust/nsstring/gtest/test.rs
@@ -0,0 +1,112 @@
+#![allow(non_snake_case)]
+
+#[macro_use]
+extern crate nsstring;
+
+use std::fmt::Write;
+use std::ffi::CString;
+use std::os::raw::c_char;
+use nsstring::*;
+
+fn nonfatal_fail(msg: String) {
+    extern "C" {
+        fn GTest_ExpectFailure(message: *const c_char);
+    }
+    unsafe {
+        GTest_ExpectFailure(CString::new(msg).unwrap().as_ptr());
+    }
+}
+
+/// This macro checks if the two arguments are equal, and causes a non-fatal
+/// GTest test failure if they are not.
+macro_rules! expect_eq {
+    ($x:expr, $y:expr) => {
+        match (&$x, &$y) {
+            (x, y) => if *x != *y {
+                nonfatal_fail(format!("check failed: (`{:?}` == `{:?}`) at {}:{}",
+                                      x, y, file!(), line!()))
+            }
+        }
+    }
+}
+
+#[no_mangle]
+pub extern fn Rust_StringFromCpp(cs: *const nsACString, s: *const nsAString) {
+    unsafe {
+        expect_eq!(&*cs, "Hello, World!");
+        expect_eq!(&*s, "Hello, World!");
+    }
+}
+
+#[no_mangle]
+pub extern fn Rust_AssignFromRust(cs: *mut nsACString, s: *mut nsAString) {
+    unsafe {
+        (*cs).assign(&nsCString::from("Hello, World!"));
+        expect_eq!(&*cs, "Hello, World!");
+        (*s).assign(&nsString::from("Hello, World!"));
+        expect_eq!(&*s, "Hello, World!");
+    }
+}
+
+extern "C" {
+    fn Cpp_AssignFromCpp(cs: *mut nsACString, s: *mut nsAString);
+}
+
+#[no_mangle]
+pub extern fn Rust_AssignFromCpp() {
+    let mut cs = nsCString::new();
+    let mut s = nsString::new();
+    unsafe {
+        Cpp_AssignFromCpp(&mut *cs, &mut *s);
+    }
+    expect_eq!(cs, "Hello, World!");
+    expect_eq!(s, "Hello, World!");
+}
+
+#[no_mangle]
+pub extern fn Rust_FixedAssignFromCpp() {
+    let mut cs_buf: [u8; 64] = [0; 64];
+    let cs_buf_ptr = &cs_buf as *const _ as usize;
+    let mut s_buf: [u16; 64] = [0; 64];
+    let s_buf_ptr = &s_buf as *const _ as usize;
+    let mut cs = nsFixedCString::new(&mut cs_buf);
+    let mut s = nsFixedString::new(&mut s_buf);
+    unsafe {
+        Cpp_AssignFromCpp(&mut *cs, &mut *s);
+    }
+    expect_eq!(cs, "Hello, World!");
+    expect_eq!(s, "Hello, World!");
+    expect_eq!(cs.as_ptr() as usize, cs_buf_ptr);
+    expect_eq!(s.as_ptr() as usize, s_buf_ptr);
+}
+
+#[no_mangle]
+pub extern fn Rust_AutoAssignFromCpp() {
+    ns_auto_cstring!(cs);
+    ns_auto_string!(s);
+    unsafe {
+        Cpp_AssignFromCpp(&mut *cs, &mut *s);
+    }
+    expect_eq!(cs, "Hello, World!");
+    expect_eq!(s, "Hello, World!");
+}
+
+#[no_mangle]
+pub extern fn Rust_StringWrite() {
+    ns_auto_cstring!(cs);
+    ns_auto_string!(s);
+
+    write!(s, "a").unwrap();
+    write!(cs, "a").unwrap();
+    expect_eq!(s, "a");
+    expect_eq!(cs, "a");
+    write!(s, "bc").unwrap();
+    write!(cs, "bc").unwrap();
+    expect_eq!(s, "abc");
+    expect_eq!(cs, "abc");
+    write!(s, "{}", 123).unwrap();
+    write!(cs, "{}", 123).unwrap();
+    expect_eq!(s, "abc123");
+    expect_eq!(cs, "abc123");
+}
+
diff --git a/xpcom/rust/nsstring/src/lib.rs b/xpcom/rust/nsstring/src/lib.rs
new file mode 100644
index 000000000..cd518f3c5
--- /dev/null
+++ b/xpcom/rust/nsstring/src/lib.rs
@@ -0,0 +1,853 @@
+//! This module provides rust bindings for the XPCOM string types.
+//!
+//! # TL;DR (what types should I use)
+//!
+//! Use `&{mut,} nsA[C]String` for functions in rust which wish to take or
+//! mutate XPCOM strings. The other string types `Deref` to this type.
+//!
+//! Use `ns[C]String<'a>` for string struct members which don't leave rust, and
+//! as an intermediate between rust string data structures (such as `String`,
+//! `Vec<u16>`, `&str`, and `&[u16]`) and `&{mut,} nsA[C]String` (using
+//! `ns[C]String::from(value)`). These conversions, when possible, will not
+//! perform any allocations.
+//!
+//! Use `nsFixed[C]String` or `ns_auto_[c]string!` for dynamic stack allocated
+//! strings which are expected to hold short string values.
+//!
+//! Use `*{const,mut} nsA[C]String` (`{const,} nsA[C]String*` in C++) for
+//! function arguments passed across the rust/C++ language boundary.
+//!
+//! Use `ns[C]StringRepr` for string struct members which are shared between
+//! rust and C++, but be careful, because this type lacks a `Drop`
+//! implementation.
+//!
+//! # String Types
+//!
+//! ## `nsA[C]String`
+//!
+//! The core types in this module are `nsAString` and `nsACString`. These types
+//! are zero-sized as far as rust is concerned, and are safe to pass around
+//! behind both references (in rust code), and pointers (in C++ code). They
+//! represent a handle to a XPCOM string which holds either `u16` or `u8`
+//! characters respectively. The backing character buffer is guaranteed to live
+//! as long as the reference to the `nsAString` or `nsACString`.
+//!
+//! These types in rust are simply used as dummy types. References to them
+//! represent a pointer to the beginning of a variable-sized `#[repr(C)]` struct
+//! which is common between both C++ and Rust implementations. In C++, their
+//! corresponding types are also named `nsAString` or `nsACString`, and they are
+//! defined within the `nsTSubstring.{cpp,h}` file.
+//!
+//! ### Valid Operations
+//!
+//! An `&nsA[C]String` acts like rust's `&str`, in that it is a borrowed
+//! reference to the backing data. When used as an argument to other functions
+//! on `&mut nsA[C]String`, optimizations can be performed to avoid copying
+//! buffers, as information about the backing storage is preserved.
+//!
+//! An `&mut nsA[C]String` acts like rust's `&mut Cow<str>`, in that it is a
+//! mutable reference to a potentially borrowed string, which when modified will
+//! ensure that it owns its own backing storage. This type can be appended to
+//! with the methods `.append`, `.append_utf{8,16}`, and with the `write!`
+//! macro, and can be assigned to with `.assign`.
+//!
+//! ## `ns[C]String<'a>`
+//!
+//! This type is an maybe-owned string type. It acts similarially to a
+//! `Cow<[{u8,u16}]>`. This type provides `Deref` and `DerefMut` implementations
+//! to `nsA[C]String`, which provides the methods for manipulating this type.
+//! This type's lifetime parameter, `'a`, represents the lifetime of the backing
+//! storage. When modified this type may re-allocate in order to ensure that it
+//! does not mutate its backing storage.
+//!
+//! `ns[C]String`s can be constructed either with `ns[C]String::new()`, which
+//! creates an empty `ns[C]String<'static>`, or through one of the provided
+//! `From` implementations. Both string types may be constructed `From<&'a
+//! str>`, with `nsCString` having a `'a` lifetime, as the storage is shared
+//! with the `str`, while `nsString` has a `'static` lifetime, as its storage
+//! has to be transcoded.
+//!
+//! When passing this type by reference, prefer passing a `&nsA[C]String` or
+//! `&mut nsA[C]String`. to passing this type.
+//!
+//! This type is _not_ `#[repr(C)]`, as it has a `Drop` impl, which in versions
+//! of `rustc < 1.13` adds drop flags to the struct, which messes up the layout,
+//! making it unsafe to pass across the FFI boundary. The rust compiler will
+//! warn if this type appears in `extern "C"` function definitions.
+//!
+//! When passing this type across the language boundary, pass it as `*const
+//! nsA[C]String` for an immutable reference, or `*mut nsA[C]String` for a
+//! mutable reference.
+//!
+//! This type is similar to the C++ type of the same name.
+//!
+//! ## `nsFixed[C]String<'a>`
+//!
+//! This type is a string type with fixed backing storage. It is created with
+//! `nsFixed[C]String::new(buffer)`, passing a mutable reference to a buffer as
+//! the argument. This buffer will be used as backing storage whenever the
+//! resulting string will fit within it, falling back to heap allocations only
+//! when the string size exceeds that of the backing buffer.
+//!
+//! Like `ns[C]String`, this type dereferences to `nsA[C]String` which provides
+//! the methods for manipulating the type, and is not `#[repr(C)]`.
+//!
+//! When passing this type by reference, prefer passing a `&nsA[C]String` or
+//! `&mut nsA[C]String`. to passing this type.
+//!
+//! This type is _not_ `#[repr(C)]`, as it has a `Drop` impl, which in versions
+//! of `rustc < 1.13` adds drop flags to the struct, which messes up the layout,
+//! making it unsafe to pass across the FFI boundary. The rust compiler will
+//! warn if this type appears in `extern "C"` function definitions.
+//!
+//! When passing this type across the language boundary, pass it as `*const
+//! nsA[C]String` for an immutable reference, or `*mut nsA[C]String` for a
+//! mutable reference.
+//!
+//! This type is similar to the C++ type of the same name.
+//!
+//! ## `ns_auto_[c]string!($name)`
+//!
+//! This is a helper macro which defines a fixed size, (currently 64 character),
+//! backing array on the stack, and defines a local variable with name `$name`
+//! which is a `nsFixed[C]String` using this buffer as its backing storage.
+//!
+//! Usage of this macro is similar to the C++ type `nsAuto[C]String`, but could
+//! not be implemented as a basic type due to the differences between rust and
+//! C++'s move semantics.
+//!
+//! ## `ns[C]StringRepr`
+//!
+//! This type represents a C++ `ns[C]String`. This type is `#[repr(C)]` and is
+//! safe to use in struct definitions which are shared across the language
+//! boundary. It automatically dereferences to `&{mut,} nsA[C]String`, and thus
+//! can be treated similarially to `ns[C]String`.
+//!
+//! If this type is dropped in rust, it will not free its backing storage. This
+//! is because types implementing `Drop` have a drop flag added, which messes up
+//! the layout of this type. When drop flags are removed, which should happen in
+//! `rustc 1.13` (see rust-lang/rust#35764), this type will likely be removed,
+//! and replaced with direct usage of `ns[C]String<'a>`, as its layout may be
+//! identical. This module provides rust bindings to our xpcom ns[C]String
+//! types.
+
+#![allow(non_camel_case_types)]
+
+use std::ops::{Deref, DerefMut};
+use std::marker::PhantomData;
+use std::slice;
+use std::ptr;
+use std::mem;
+use std::fmt;
+use std::cmp;
+use std::str;
+use std::u32;
+
+//////////////////////////////////
+// Internal Implemenation Flags //
+//////////////////////////////////
+
+const F_NONE: u32 = 0; // no flags
+
+// data flags are in the lower 16-bits
+const F_TERMINATED: u32 = 1 << 0; // IsTerminated returns true
+const F_VOIDED: u32 = 1 << 1; // IsVoid returns true
+const F_SHARED: u32 = 1 << 2; // mData points to a heap-allocated, shared buffer
+const F_OWNED: u32 = 1 << 3; // mData points to a heap-allocated, raw buffer
+const F_FIXED: u32 = 1 << 4; // mData points to a fixed-size writable, dependent buffer
+const F_LITERAL: u32 = 1 << 5; // mData points to a string literal; F_TERMINATED will also be set
+
+// class flags are in the upper 16-bits
+const F_CLASS_FIXED: u32 = 1 << 16; // indicates that |this| is of type nsTFixedString
+
+////////////////////////////////////
+// Generic String Bindings Macros //
+////////////////////////////////////
+
+macro_rules! define_string_types {
+    {
+        char_t = $char_t: ty;
+        AString = $AString: ident;
+        String = $String: ident;
+        FixedString = $FixedString: ident;
+
+        StringRepr = $StringRepr: ident;
+        FixedStringRepr = $FixedStringRepr: ident;
+        AutoStringRepr = $AutoStringRepr: ident;
+    } => {
+        /// The representation of a ns[C]String type in C++. This type is
+        /// used internally by our definition of ns[C]String to ensure layout
+        /// compatibility with the C++ ns[C]String type.
+        ///
+        /// This type may also be used in place of a C++ ns[C]String inside of
+        /// struct definitions which are shared with C++, as it has identical
+        /// layout to our ns[C]String type. Due to drop flags, our ns[C]String
+        /// type does not have identical layout. When drop flags are removed,
+        /// this type will likely be made a private implementation detail, and
+        /// its uses will be replaced with `ns[C]String`.
+        ///
+        /// This struct will leak its data if dropped from rust. See the module
+        /// documentation for more information on this type.
+        #[repr(C)]
+        pub struct $StringRepr {
+            data: *const $char_t,
+            length: u32,
+            flags: u32,
+        }
+
+        impl Deref for $StringRepr {
+            type Target = $AString;
+            fn deref(&self) -> &$AString {
+                unsafe {
+                    mem::transmute(self)
+                }
+            }
+        }
+
+        impl DerefMut for $StringRepr {
+            fn deref_mut(&mut self) -> &mut $AString {
+                unsafe {
+                    mem::transmute(self)
+                }
+            }
+        }
+
+        /// The representation of a nsFixed[C]String type in C++. This type is
+        /// used internally by our definition of nsFixed[C]String to ensure layout
+        /// compatibility with the C++ nsFixed[C]String type.
+        #[repr(C)]
+        struct $FixedStringRepr {
+            base: $StringRepr,
+            capacity: u32,
+            buffer: *mut $char_t,
+        }
+
+        /// This type is the abstract type which is used for interacting with
+        /// strings in rust. Each string type can derefence to an instance of
+        /// this type, which provides the useful operations on strings.
+        ///
+        /// NOTE: Rust thinks this type has a size of 0, because the data
+        /// associated with it is not necessarially safe to move. It is not safe
+        /// to construct a nsAString yourself, unless it is received by
+        /// dereferencing one of these types.
+        ///
+        /// NOTE: The `[u8; 0]` member is zero sized, and only exists to prevent
+        /// the construction by code outside of this module. It is used instead
+        /// of a private `()` member because the `improper_ctypes` lint complains
+        /// about some ZST members in `extern "C"` function declarations.
+        #[repr(C)]
+        pub struct $AString {
+            _prohibit_constructor: [u8; 0],
+        }
+
+        impl Deref for $AString {
+            type Target = [$char_t];
+            fn deref(&self) -> &[$char_t] {
+                unsafe {
+                    // This is legal, as all $AString values actually point to a
+                    // $StringRepr
+                    let this: &$StringRepr = mem::transmute(self);
+                    if this.data.is_null() {
+                        debug_assert!(this.length == 0);
+                        // Use an arbitrary non-null value as the pointer
+                        slice::from_raw_parts(0x1 as *const $char_t, 0)
+                    } else {
+                        slice::from_raw_parts(this.data, this.length as usize)
+                    }
+                }
+            }
+        }
+
+        impl cmp::PartialEq for $AString {
+            fn eq(&self, other: &$AString) -> bool {
+                &self[..] == &other[..]
+            }
+        }
+
+        impl cmp::PartialEq<[$char_t]> for $AString {
+            fn eq(&self, other: &[$char_t]) -> bool {
+                &self[..] == other
+            }
+        }
+
+        impl<'a> cmp::PartialEq<$String<'a>> for $AString {
+            fn eq(&self, other: &$String<'a>) -> bool {
+                self.eq(&**other)
+            }
+        }
+
+        impl<'a> cmp::PartialEq<$FixedString<'a>> for $AString {
+            fn eq(&self, other: &$FixedString<'a>) -> bool {
+                self.eq(&**other)
+            }
+        }
+
+        pub struct $String<'a> {
+            hdr: $StringRepr,
+            _marker: PhantomData<&'a [$char_t]>,
+        }
+
+        impl $String<'static> {
+            pub fn new() -> $String<'static> {
+                $String {
+                    hdr: $StringRepr {
+                        data: ptr::null(),
+                        length: 0,
+                        flags: F_NONE,
+                    },
+                    _marker: PhantomData,
+                }
+            }
+        }
+
+        impl<'a> Deref for $String<'a> {
+            type Target = $AString;
+            fn deref(&self) -> &$AString {
+                &self.hdr
+            }
+        }
+
+        impl<'a> DerefMut for $String<'a> {
+            fn deref_mut(&mut self) -> &mut $AString {
+                &mut self.hdr
+            }
+        }
+
+        impl<'a> From<&'a String> for $String<'a> {
+            fn from(s: &'a String) -> $String<'a> {
+                $String::from(&s[..])
+            }
+        }
+
+        impl<'a> From<&'a Vec<$char_t>> for $String<'a> {
+            fn from(s: &'a Vec<$char_t>) -> $String<'a> {
+                $String::from(&s[..])
+            }
+        }
+
+        impl<'a> From<&'a [$char_t]> for $String<'a> {
+            fn from(s: &'a [$char_t]) -> $String<'a> {
+                assert!(s.len() < (u32::MAX as usize));
+                $String {
+                    hdr: $StringRepr {
+                        data: s.as_ptr(),
+                        length: s.len() as u32,
+                        flags: F_NONE,
+                    },
+                    _marker: PhantomData,
+                }
+            }
+        }
+
+        impl From<Box<[$char_t]>> for $String<'static> {
+            fn from(s: Box<[$char_t]>) -> $String<'static> {
+                assert!(s.len() < (u32::MAX as usize));
+                // SAFETY NOTE: This method produces an F_OWNED ns[C]String from
+                // a Box<[$char_t]>. this is only safe because in the Gecko
+                // tree, we use the same allocator for Rust code as for C++
+                // code, meaning that our box can be legally freed with
+                // libc::free().
+                let length = s.len() as u32;
+                let ptr = s.as_ptr();
+                mem::forget(s);
+                $String {
+                    hdr: $StringRepr {
+                        data: ptr,
+                        length: length,
+                        flags: F_OWNED,
+                    },
+                    _marker: PhantomData,
+                }
+            }
+        }
+
+        impl From<Vec<$char_t>> for $String<'static> {
+            fn from(s: Vec<$char_t>) -> $String<'static> {
+                s.into_boxed_slice().into()
+            }
+        }
+
+        impl<'a> From<&'a $AString> for $String<'static> {
+            fn from(s: &'a $AString) -> $String<'static> {
+                let mut string = $String::new();
+                string.assign(s);
+                string
+            }
+        }
+
+        impl<'a> fmt::Write for $String<'a> {
+            fn write_str(&mut self, s: &str) -> Result<(), fmt::Error> {
+                $AString::write_str(self, s)
+            }
+        }
+
+        impl<'a> fmt::Display for $String<'a> {
+            fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+                <$AString as fmt::Display>::fmt(self, f)
+            }
+        }
+
+        impl<'a> fmt::Debug for $String<'a> {
+            fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+                <$AString as fmt::Debug>::fmt(self, f)
+            }
+        }
+
+        impl<'a> cmp::PartialEq for $String<'a> {
+            fn eq(&self, other: &$String<'a>) -> bool {
+                $AString::eq(self, other)
+            }
+        }
+
+        impl<'a> cmp::PartialEq<[$char_t]> for $String<'a> {
+            fn eq(&self, other: &[$char_t]) -> bool {
+                $AString::eq(self, other)
+            }
+        }
+
+        impl<'a, 'b> cmp::PartialEq<&'b [$char_t]> for $String<'a> {
+            fn eq(&self, other: &&'b [$char_t]) -> bool {
+                $AString::eq(self, *other)
+            }
+        }
+
+        impl<'a> cmp::PartialEq<str> for $String<'a> {
+            fn eq(&self, other: &str) -> bool {
+                $AString::eq(self, other)
+            }
+        }
+
+        impl<'a, 'b> cmp::PartialEq<&'b str> for $String<'a> {
+            fn eq(&self, other: &&'b str) -> bool {
+                $AString::eq(self, *other)
+            }
+        }
+
+        impl<'a> Drop for $String<'a> {
+            fn drop(&mut self) {
+                unsafe {
+                    self.finalize();
+                }
+            }
+        }
+
+        /// A nsFixed[C]String is a string which uses a fixed size mutable
+        /// backing buffer for storing strings which will fit within that
+        /// buffer, rather than using heap allocations.
+        pub struct $FixedString<'a> {
+            hdr: $FixedStringRepr,
+            _marker: PhantomData<&'a mut [$char_t]>,
+        }
+
+        impl<'a> $FixedString<'a> {
+            pub fn new(buf: &'a mut [$char_t]) -> $FixedString<'a> {
+                let len = buf.len();
+                assert!(len < (u32::MAX as usize));
+                let buf_ptr = buf.as_mut_ptr();
+                $FixedString {
+                    hdr: $FixedStringRepr {
+                        base: $StringRepr {
+                            data: ptr::null(),
+                            length: 0,
+                            flags: F_CLASS_FIXED,
+                        },
+                        capacity: len as u32,
+                        buffer: buf_ptr,
+                    },
+                    _marker: PhantomData,
+                }
+            }
+        }
+
+        impl<'a> Deref for $FixedString<'a> {
+            type Target = $AString;
+            fn deref(&self) -> &$AString {
+                &self.hdr.base
+            }
+        }
+
+        impl<'a> DerefMut for $FixedString<'a> {
+            fn deref_mut(&mut self) -> &mut $AString {
+                &mut self.hdr.base
+            }
+        }
+
+        impl<'a> fmt::Write for $FixedString<'a> {
+            fn write_str(&mut self, s: &str) -> Result<(), fmt::Error> {
+                $AString::write_str(self, s)
+            }
+        }
+
+        impl<'a> fmt::Display for $FixedString<'a> {
+            fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+                <$AString as fmt::Display>::fmt(self, f)
+            }
+        }
+
+        impl<'a> fmt::Debug for $FixedString<'a> {
+            fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+                <$AString as fmt::Debug>::fmt(self, f)
+            }
+        }
+
+        impl<'a> cmp::PartialEq for $FixedString<'a> {
+            fn eq(&self, other: &$FixedString<'a>) -> bool {
+                $AString::eq(self, other)
+            }
+        }
+
+        impl<'a> cmp::PartialEq<[$char_t]> for $FixedString<'a> {
+            fn eq(&self, other: &[$char_t]) -> bool {
+                $AString::eq(self, other)
+            }
+        }
+
+        impl<'a, 'b> cmp::PartialEq<&'b [$char_t]> for $FixedString<'a> {
+            fn eq(&self, other: &&'b [$char_t]) -> bool {
+                $AString::eq(self, *other)
+            }
+        }
+
+        impl<'a> cmp::PartialEq<str> for $FixedString<'a> {
+            fn eq(&self, other: &str) -> bool {
+                $AString::eq(self, other)
+            }
+        }
+
+        impl<'a, 'b> cmp::PartialEq<&'b str> for $FixedString<'a> {
+            fn eq(&self, other: &&'b str) -> bool {
+                $AString::eq(self, *other)
+            }
+        }
+
+        impl<'a> Drop for $FixedString<'a> {
+            fn drop(&mut self) {
+                unsafe {
+                    self.finalize();
+                }
+            }
+        }
+    }
+}
+
+///////////////////////////////////////////
+// Bindings for nsCString (u8 char type) //
+///////////////////////////////////////////
+
+define_string_types! {
+    char_t = u8;
+
+    AString = nsACString;
+    String = nsCString;
+    FixedString = nsFixedCString;
+
+    StringRepr = nsCStringRepr;
+    FixedStringRepr = nsFixedCStringRepr;
+    AutoStringRepr = nsAutoCStringRepr;
+}
+
+impl nsACString {
+    /// Leaves the nsACString in an unstable state with a dangling data pointer.
+    /// Should only be used in drop implementations of rust types which wrap
+    /// this type.
+    unsafe fn finalize(&mut self) {
+        Gecko_FinalizeCString(self);
+    }
+
+    pub fn assign(&mut self, other: &nsACString) {
+        unsafe {
+            Gecko_AssignCString(self as *mut _, other as *const _);
+        }
+    }
+
+    pub fn assign_utf16(&mut self, other: &nsAString) {
+        self.assign(&nsCString::new());
+        self.append_utf16(other);
+    }
+
+    pub fn append(&mut self, other: &nsACString) {
+        unsafe {
+            Gecko_AppendCString(self as *mut _, other as *const _);
+        }
+    }
+
+    pub fn append_utf16(&mut self, other: &nsAString) {
+        unsafe {
+            Gecko_AppendUTF16toCString(self as *mut _, other as *const _);
+        }
+    }
+
+    pub unsafe fn as_str_unchecked(&self) -> &str {
+        str::from_utf8_unchecked(self)
+    }
+}
+
+impl<'a> From<&'a str> for nsCString<'a> {
+    fn from(s: &'a str) -> nsCString<'a> {
+        s.as_bytes().into()
+    }
+}
+
+impl From<Box<str>> for nsCString<'static> {
+    fn from(s: Box<str>) -> nsCString<'static> {
+        s.into_string().into()
+    }
+}
+
+impl From<String> for nsCString<'static> {
+    fn from(s: String) -> nsCString<'static> {
+        s.into_bytes().into()
+    }
+}
+
+// Support for the write!() macro for appending to nsACStrings
+impl fmt::Write for nsACString {
+    fn write_str(&mut self, s: &str) -> Result<(), fmt::Error> {
+        self.append(&nsCString::from(s));
+        Ok(())
+    }
+}
+
+impl fmt::Display for nsACString {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        fmt::Display::fmt(&String::from_utf8_lossy(&self[..]), f)
+    }
+}
+
+impl fmt::Debug for nsACString {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        fmt::Debug::fmt(&String::from_utf8_lossy(&self[..]), f)
+    }
+}
+
+impl cmp::PartialEq<str> for nsACString {
+    fn eq(&self, other: &str) -> bool {
+        &self[..] == other.as_bytes()
+    }
+}
+
+#[macro_export]
+macro_rules! ns_auto_cstring {
+    ($name:ident) => {
+        let mut buf: [u8; 64] = [0; 64];
+        let mut $name = $crate::nsFixedCString::new(&mut buf);
+    }
+}
+
+///////////////////////////////////////////
+// Bindings for nsString (u16 char type) //
+///////////////////////////////////////////
+
+define_string_types! {
+    char_t = u16;
+
+    AString = nsAString;
+    String = nsString;
+    FixedString = nsFixedString;
+
+    StringRepr = nsStringRepr;
+    FixedStringRepr = nsFixedStringRepr;
+    AutoStringRepr = nsAutoStringRepr;
+}
+
+impl nsAString {
+    /// Leaves the nsAString in an unstable state with a dangling data pointer.
+    /// Should only be used in drop implementations of rust types which wrap
+    /// this type.
+    unsafe fn finalize(&mut self) {
+        Gecko_FinalizeString(self);
+    }
+
+    pub fn assign(&mut self, other: &nsAString) {
+        unsafe {
+            Gecko_AssignString(self as *mut _, other as *const _);
+        }
+    }
+
+    pub fn assign_utf8(&mut self, other: &nsACString) {
+        self.assign(&nsString::new());
+        self.append_utf8(other);
+    }
+
+    pub fn append(&mut self, other: &nsAString) {
+        unsafe {
+            Gecko_AppendString(self as *mut _, other as *const _);
+        }
+    }
+
+    pub fn append_utf8(&mut self, other: &nsACString) {
+        unsafe {
+            Gecko_AppendUTF8toString(self as *mut _, other as *const _);
+        }
+    }
+}
+
+// NOTE: The From impl for a string slice for nsString produces a <'static>
+// lifetime, as it allocates.
+impl<'a> From<&'a str> for nsString<'static> {
+    fn from(s: &'a str) -> nsString<'static> {
+        s.encode_utf16().collect::<Vec<u16>>().into()
+    }
+}
+
+// Support for the write!() macro for writing to nsStrings
+impl fmt::Write for nsAString {
+    fn write_str(&mut self, s: &str) -> Result<(), fmt::Error> {
+        // Directly invoke gecko's routines for appending utf8 strings to
+        // nsAString values, to avoid as much overhead as possible
+        self.append_utf8(&nsCString::from(s));
+        Ok(())
+    }
+}
+
+impl fmt::Display for nsAString {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        fmt::Display::fmt(&String::from_utf16_lossy(&self[..]), f)
+    }
+}
+
+impl fmt::Debug for nsAString {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        fmt::Debug::fmt(&String::from_utf16_lossy(&self[..]), f)
+    }
+}
+
+impl cmp::PartialEq<str> for nsAString {
+    fn eq(&self, other: &str) -> bool {
+        other.encode_utf16().eq(self.iter().cloned())
+    }
+}
+
+#[macro_export]
+macro_rules! ns_auto_string {
+    ($name:ident) => {
+        let mut buf: [u16; 64] = [0; 64];
+        let mut $name = $crate::nsFixedString::new(&mut buf);
+    }
+}
+
+// NOTE: These bindings currently only expose infallible operations. Perhaps
+// consider allowing for fallible methods?
+extern "C" {
+    // Gecko implementation in nsSubstring.cpp
+    fn Gecko_FinalizeCString(this: *mut nsACString);
+    fn Gecko_AssignCString(this: *mut nsACString, other: *const nsACString);
+    fn Gecko_AppendCString(this: *mut nsACString, other: *const nsACString);
+
+    fn Gecko_FinalizeString(this: *mut nsAString);
+    fn Gecko_AssignString(this: *mut nsAString, other: *const nsAString);
+    fn Gecko_AppendString(this: *mut nsAString, other: *const nsAString);
+
+    // Gecko implementation in nsReadableUtils.cpp
+    fn Gecko_AppendUTF16toCString(this: *mut nsACString, other: *const nsAString);
+    fn Gecko_AppendUTF8toString(this: *mut nsAString, other: *const nsACString);
+}
+
+//////////////////////////////////////
+// Repr Validation Helper Functions //
+//////////////////////////////////////
+
+pub mod test_helpers {
+    //! This module only exists to help with ensuring that the layout of the
+    //! structs inside of rust and C++ are identical.
+    //!
+    //! It is public to ensure that these testing functions are avaliable to
+    //! gtest code.
+
+    use super::{
+        nsFixedCStringRepr,
+        nsFixedStringRepr,
+        nsCStringRepr,
+        nsStringRepr,
+        F_NONE,
+        F_TERMINATED,
+        F_VOIDED,
+        F_SHARED,
+        F_OWNED,
+        F_FIXED,
+        F_LITERAL,
+        F_CLASS_FIXED,
+    };
+    use std::mem;
+
+    /// Generates an #[no_mangle] extern "C" function which returns the size and
+    /// alignment of the given type with the given name.
+    macro_rules! size_align_check {
+        ($T:ty, $fname:ident) => {
+            #[no_mangle]
+            #[allow(non_snake_case)]
+            pub extern fn $fname(size: *mut usize, align: *mut usize) {
+                unsafe {
+                    *size = mem::size_of::<$T>();
+                    *align = mem::align_of::<$T>();
+                }
+            }
+        }
+    }
+
+    size_align_check!(nsStringRepr, Rust_Test_ReprSizeAlign_nsString);
+    size_align_check!(nsCStringRepr, Rust_Test_ReprSizeAlign_nsCString);
+    size_align_check!(nsFixedStringRepr, Rust_Test_ReprSizeAlign_nsFixedString);
+    size_align_check!(nsFixedCStringRepr, Rust_Test_ReprSizeAlign_nsFixedCString);
+
+    /// Generates a $[no_mangle] extern "C" function which returns the size,
+    /// alignment and offset in the parent struct of a given member, with the
+    /// given name.
+    ///
+    /// This method can trigger Undefined Behavior if the accessing the member
+    /// $member on a given type would use that type's `Deref` implementation.
+    macro_rules! member_check {
+        ($T:ty, $member:ident, $method:ident) => {
+            #[no_mangle]
+            #[allow(non_snake_case)]
+            pub extern fn $method(size: *mut usize,
+                                  align: *mut usize,
+                                  offset: *mut usize) {
+                unsafe {
+                    // Create a temporary value of type T to get offsets, sizes
+                    // and aligns off of
+                    let tmp: $T = mem::zeroed();
+                    *size = mem::size_of_val(&tmp.$member);
+                    *align = mem::align_of_val(&tmp.$member);
+                    *offset =
+                        (&tmp.$member as *const _ as usize) -
+                        (&tmp as *const _ as usize);
+                    mem::forget(tmp);
+                }
+            }
+        }
+    }
+
+    member_check!(nsStringRepr, data, Rust_Test_Member_nsString_mData);
+    member_check!(nsStringRepr, length, Rust_Test_Member_nsString_mLength);
+    member_check!(nsStringRepr, flags, Rust_Test_Member_nsString_mFlags);
+    member_check!(nsCStringRepr, data, Rust_Test_Member_nsCString_mData);
+    member_check!(nsCStringRepr, length, Rust_Test_Member_nsCString_mLength);
+    member_check!(nsCStringRepr, flags, Rust_Test_Member_nsCString_mFlags);
+    member_check!(nsFixedStringRepr, capacity, Rust_Test_Member_nsFixedString_mFixedCapacity);
+    member_check!(nsFixedStringRepr, buffer, Rust_Test_Member_nsFixedString_mFixedBuf);
+    member_check!(nsFixedCStringRepr, capacity, Rust_Test_Member_nsFixedCString_mFixedCapacity);
+    member_check!(nsFixedCStringRepr, buffer, Rust_Test_Member_nsFixedCString_mFixedBuf);
+
+    #[no_mangle]
+    #[allow(non_snake_case)]
+    pub extern fn Rust_Test_NsStringFlags(f_none: *mut u32,
+                                          f_terminated: *mut u32,
+                                          f_voided: *mut u32,
+                                          f_shared: *mut u32,
+                                          f_owned: *mut u32,
+                                          f_fixed: *mut u32,
+                                          f_literal: *mut u32,
+                                          f_class_fixed: *mut u32) {
+        unsafe {
+            *f_none = F_NONE;
+            *f_terminated = F_TERMINATED;
+            *f_voided = F_VOIDED;
+            *f_shared = F_SHARED;
+            *f_owned = F_OWNED;
+            *f_fixed = F_FIXED;
+            *f_literal = F_LITERAL;
+            *f_class_fixed = F_CLASS_FIXED;
+        }
+    }
+}
diff --git a/xpcom/string/README.html b/xpcom/string/README.html
new file mode 100644
index 000000000..4a0927c65
--- /dev/null
+++ b/xpcom/string/README.html
@@ -0,0 +1,11 @@
+<html>
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<body>
+  <h1><span class="LXRSHORTDESC">managing sequences of characters</span></h1>
+<p>
+  <span class="LXRLONGDESC"></span>
+</p>
+</body>
+</html>
diff --git a/xpcom/string/crashtests/1113005-frame.html b/xpcom/string/crashtests/1113005-frame.html
new file mode 100644
index 000000000..505fc22f1
--- /dev/null
+++ b/xpcom/string/crashtests/1113005-frame.html
@@ -0,0 +1,5 @@
+<form method=post enctype=multipart/form-data action="data:text/html,"><textarea name='file"; filename="filename.ext
+ '></textarea>
+<script>
+document.forms[0].submit();
+</script>
diff --git a/xpcom/string/crashtests/1113005.html b/xpcom/string/crashtests/1113005.html
new file mode 100644
index 000000000..e377bb637
--- /dev/null
+++ b/xpcom/string/crashtests/1113005.html
@@ -0,0 +1,2 @@
+<!DOCTYPE html>
+<iframe src="1113005-frame.html"></iframe>
diff --git a/xpcom/string/crashtests/394275-1.html b/xpcom/string/crashtests/394275-1.html
new file mode 100644
index 000000000..4f2afd1a6
--- /dev/null
+++ b/xpcom/string/crashtests/394275-1.html
@@ -0,0 +1,9 @@
+<html>
+<body>
+<script>
+style = document.createElement("style");
+document.documentElement.appendChild(style);
+style.textContent = "tz\uDAB2 ";
+</script>
+</body>
+</html>
diff --git a/xpcom/string/crashtests/395651-1.html b/xpcom/string/crashtests/395651-1.html
new file mode 100644
index 000000000..3f89a0836
--- /dev/null
+++ b/xpcom/string/crashtests/395651-1.html
@@ -0,0 +1,31 @@
+<html>
+<head>
+<script>
+
+function X() { dump("X\n"); }
+function Y() { dump("Y\n"); }
+
+function boom()
+{
+  dump("Start9\n");
+
+  var div = document.getElementById("v");
+
+  var textNode = document.createTextNode(String.fromCharCode(0xDAAF)); // high surrogate
+  div.appendChild(textNode);
+
+  document.addEventListener("DOMCharacterDataModified", X, true);
+  textNode.data += 'B';
+  document.removeEventListener("DOMCharacterDataModified", X, true);
+
+  document.addEventListener("DOMAttrModified", Y, true);
+  textNode.data += String.fromCharCode(0xDF53); // low surrogate
+  document.removeEventListener("DOMAttrModified", Y, true);
+}
+
+</script>
+</head>
+
+<body onload="boom();"><div id="v"></div></body>
+
+</html>
diff --git a/xpcom/string/crashtests/crashtests.list b/xpcom/string/crashtests/crashtests.list
new file mode 100644
index 000000000..8562f1ad8
--- /dev/null
+++ b/xpcom/string/crashtests/crashtests.list
@@ -0,0 +1,3 @@
+load 394275-1.html
+load 395651-1.html
+load 1113005.html
diff --git a/xpcom/string/moz.build b/xpcom/string/moz.build
new file mode 100644
index 000000000..6ad7d7cc8
--- /dev/null
+++ b/xpcom/string/moz.build
@@ -0,0 +1,61 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+with Files('**'):
+    BUG_COMPONENT = ('Core', 'String')
+
+EXPORTS += [
+    'nsAString.h',
+    'nsCharTraits.h',
+    'nsDependentString.h',
+    'nsDependentSubstring.h',
+    'nsEmbedString.h',
+    'nsLiteralString.h',
+    'nsPrintfCString.h',
+    'nsPromiseFlatString.h',
+    'nsReadableUtils.h',
+    'nsString.h',
+    'nsStringBuffer.h',
+    'nsStringFwd.h',
+    'nsStringIterator.h',
+    'nsSubstring.h',
+    'nsSubstringTuple.h',
+    'nsTDependentString.h',
+    'nsTDependentSubstring.h',
+    'nsTLiteralString.h',
+    'nsTPromiseFlatString.h',
+    'nsTString.h',
+    'nsTSubstring.h',
+    'nsTSubstringTuple.h',
+    'nsUTF8Utils.h',
+    'nsXPCOMStrings.h',
+    'nsXPIDLString.h',
+    'string-template-def-char.h',
+    'string-template-def-unichar.h',
+    'string-template-undef.h',
+]
+
+UNIFIED_SOURCES += [
+    'nsDependentString.cpp',
+    'nsDependentSubstring.cpp',
+    'nsPromiseFlatString.cpp',
+    'nsReadableUtils.cpp',
+    'nsString.cpp',
+    'nsStringComparator.cpp',
+    'nsStringObsolete.cpp',
+    'nsSubstring.cpp',
+    'nsSubstringTuple.cpp',
+]
+
+# Are we targeting x86 or x86-64?  If so, compile the SSE2 functions for
+# nsUTF8Utils.cpp and nsReadableUtils.cpp.
+if CONFIG['INTEL_ARCHITECTURE']:
+    SOURCES += ['nsUTF8UtilsSSE2.cpp']
+    SOURCES['nsUTF8UtilsSSE2.cpp'].flags += CONFIG['SSE2_FLAGS']
+    SOURCES += ['nsReadableUtilsSSE2.cpp']
+    SOURCES['nsReadableUtilsSSE2.cpp'].flags += CONFIG['SSE2_FLAGS']
+
+FINAL_LIBRARY = 'xul'
diff --git a/xpcom/string/nsAString.h b/xpcom/string/nsAString.h
new file mode 100644
index 000000000..0cbea0dc7
--- /dev/null
+++ b/xpcom/string/nsAString.h
@@ -0,0 +1,62 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+// IWYU pragma: private, include "nsString.h"
+
+#ifndef nsAString_h___
+#define nsAString_h___
+
+#include "nsStringFwd.h"
+#include "nsStringIterator.h"
+
+#include <string.h>
+#include <stdarg.h>
+
+#define kNotFound -1
+
+// declare nsAString
+#include "string-template-def-unichar.h"
+#include "nsTSubstring.h"
+#include "string-template-undef.h"
+
+// declare nsACString
+#include "string-template-def-char.h"
+#include "nsTSubstring.h"
+#include "string-template-undef.h"
+
+
+/**
+ * ASCII case-insensitive comparator.  (for Unicode case-insensitive
+ * comparision, see nsUnicharUtils.h)
+ */
+class nsCaseInsensitiveCStringComparator
+  : public nsCStringComparator
+{
+public:
+  nsCaseInsensitiveCStringComparator()
+  {
+  }
+  typedef char char_type;
+
+  virtual int operator()(const char_type*, const char_type*,
+                         uint32_t, uint32_t) const override;
+};
+
+class nsCaseInsensitiveCStringArrayComparator
+{
+public:
+  template<class A, class B>
+  bool Equals(const A& aStrA, const B& aStrB) const
+  {
+    return aStrA.Equals(aStrB, nsCaseInsensitiveCStringComparator());
+  }
+};
+
+// included here for backwards compatibility
+#ifndef nsSubstringTuple_h___
+#include "nsSubstringTuple.h"
+#endif
+
+#endif // !defined(nsAString_h___)
diff --git a/xpcom/string/nsCharTraits.h b/xpcom/string/nsCharTraits.h
new file mode 100644
index 000000000..d93e1f5dc
--- /dev/null
+++ b/xpcom/string/nsCharTraits.h
@@ -0,0 +1,587 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCharTraits_h___
+#define nsCharTraits_h___
+
+#include <ctype.h> // for |EOF|, |WEOF|
+#include <string.h> // for |memcpy|, et al
+
+#include "nscore.h" // for |char16_t|
+
+// This file may be used (through nsUTF8Utils.h) from non-XPCOM code, in
+// particular the standalone software updater. In that case stub out
+// the macros provided by nsDebug.h which are only usable when linking XPCOM
+
+#ifdef NS_NO_XPCOM
+#define NS_WARNING(msg)
+#define NS_ASSERTION(cond, msg)
+#define NS_ERROR(msg)
+#else
+#include "nsDebug.h"  // for NS_ASSERTION
+#endif
+
+/*
+ * Some macros for converting char16_t (UTF-16) to and from Unicode scalar
+ * values.
+ *
+ * Note that UTF-16 represents all Unicode scalar values up to U+10FFFF by
+ * using "surrogate pairs". These consist of a high surrogate, i.e. a code
+ * point in the range U+D800 - U+DBFF, and a low surrogate, i.e. a code point
+ * in the range U+DC00 - U+DFFF, like this:
+ *
+ *  U+D800 U+DC00 =  U+10000
+ *  U+D800 U+DC01 =  U+10001
+ *  ...
+ *  U+DBFF U+DFFE = U+10FFFE
+ *  U+DBFF U+DFFF = U+10FFFF
+ *
+ * These surrogate code points U+D800 - U+DFFF are not themselves valid Unicode
+ * scalar values and are not well-formed UTF-16 except as high-surrogate /
+ * low-surrogate pairs.
+ */
+
+#define PLANE1_BASE          uint32_t(0x00010000)
+// High surrogates are in the range 0xD800 -- OxDBFF
+#define NS_IS_HIGH_SURROGATE(u) ((uint32_t(u) & 0xFFFFFC00) == 0xD800)
+// Low surrogates are in the range 0xDC00 -- 0xDFFF
+#define NS_IS_LOW_SURROGATE(u)  ((uint32_t(u) & 0xFFFFFC00) == 0xDC00)
+// Faster than testing NS_IS_HIGH_SURROGATE || NS_IS_LOW_SURROGATE
+#define IS_SURROGATE(u)      ((uint32_t(u) & 0xFFFFF800) == 0xD800)
+
+// Everything else is not a surrogate: 0x000 -- 0xD7FF, 0xE000 -- 0xFFFF
+
+// N = (H - 0xD800) * 0x400 + 0x10000 + (L - 0xDC00)
+// I wonder whether we could somehow assert that H is a high surrogate
+// and L is a low surrogate
+#define SURROGATE_TO_UCS4(h, l) (((uint32_t(h) & 0x03FF) << 10) + \
+                                 (uint32_t(l) & 0x03FF) + PLANE1_BASE)
+
+// Extract surrogates from a UCS4 char
+// Reference: the Unicode standard 4.0, section 3.9
+// Since (c - 0x10000) >> 10 == (c >> 10) - 0x0080 and
+// 0xD7C0 == 0xD800 - 0x0080,
+// ((c - 0x10000) >> 10) + 0xD800 can be simplified to
+#define H_SURROGATE(c) char16_t(char16_t(uint32_t(c) >> 10) + \
+                                char16_t(0xD7C0))
+// where it's to be noted that 0xD7C0 is not bitwise-OR'd
+// but added.
+
+// Since 0x10000 & 0x03FF == 0,
+// (c - 0x10000) & 0x03FF == c & 0x03FF so that
+// ((c - 0x10000) & 0x03FF) | 0xDC00 is equivalent to
+#define L_SURROGATE(c) char16_t(char16_t(uint32_t(c) & uint32_t(0x03FF)) | \
+                                 char16_t(0xDC00))
+
+#define IS_IN_BMP(ucs) (uint32_t(ucs) < PLANE1_BASE)
+#define UCS2_REPLACEMENT_CHAR char16_t(0xFFFD)
+
+#define UCS_END uint32_t(0x00110000)
+#define IS_VALID_CHAR(c) ((uint32_t(c) < UCS_END) && !IS_SURROGATE(c))
+#define ENSURE_VALID_CHAR(c) (IS_VALID_CHAR(c) ? (c) : UCS2_REPLACEMENT_CHAR)
+
+template <class CharT>
+struct nsCharTraits
+{
+};
+
+template <>
+struct nsCharTraits<char16_t>
+{
+  typedef char16_t char_type;
+  typedef uint16_t  unsigned_char_type;
+  typedef char      incompatible_char_type;
+
+  static char_type* const sEmptyBuffer;
+
+  static void
+  assign(char_type& aLhs, char_type aRhs)
+  {
+    aLhs = aRhs;
+  }
+
+
+  // integer representation of characters:
+  typedef int int_type;
+
+  static char_type
+  to_char_type(int_type aChar)
+  {
+    return char_type(aChar);
+  }
+
+  static int_type
+  to_int_type(char_type aChar)
+  {
+    return int_type(static_cast<unsigned_char_type>(aChar));
+  }
+
+  static bool
+  eq_int_type(int_type aLhs, int_type aRhs)
+  {
+    return aLhs == aRhs;
+  }
+
+
+  // |char_type| comparisons:
+
+  static bool
+  eq(char_type aLhs, char_type aRhs)
+  {
+    return aLhs == aRhs;
+  }
+
+  static bool
+  lt(char_type aLhs, char_type aRhs)
+  {
+    return aLhs < aRhs;
+  }
+
+
+  // operations on s[n] arrays:
+
+  static char_type*
+  move(char_type* aStr1, const char_type* aStr2, size_t aN)
+  {
+    return static_cast<char_type*>(memmove(aStr1, aStr2,
+                                           aN * sizeof(char_type)));
+  }
+
+  static char_type*
+  copy(char_type* aStr1, const char_type* aStr2, size_t aN)
+  {
+    return static_cast<char_type*>(memcpy(aStr1, aStr2,
+                                          aN * sizeof(char_type)));
+  }
+
+  static char_type*
+  copyASCII(char_type* aStr1, const char* aStr2, size_t aN)
+  {
+    for (char_type* s = aStr1; aN--; ++s, ++aStr2) {
+      NS_ASSERTION(!(*aStr2 & ~0x7F), "Unexpected non-ASCII character");
+      *s = static_cast<char_type>(*aStr2);
+    }
+    return aStr1;
+  }
+
+  static char_type*
+  assign(char_type* aStr, size_t aN, char_type aChar)
+  {
+    char_type* result = aStr;
+    while (aN--) {
+      assign(*aStr++, aChar);
+    }
+    return result;
+  }
+
+  static int
+  compare(const char_type* aStr1, const char_type* aStr2, size_t aN)
+  {
+    for (; aN--; ++aStr1, ++aStr2) {
+      if (!eq(*aStr1, *aStr2)) {
+        return to_int_type(*aStr1) - to_int_type(*aStr2);
+      }
+    }
+
+    return 0;
+  }
+
+  static int
+  compareASCII(const char_type* aStr1, const char* aStr2, size_t aN)
+  {
+    for (; aN--; ++aStr1, ++aStr2) {
+      NS_ASSERTION(!(*aStr2 & ~0x7F), "Unexpected non-ASCII character");
+      if (!eq_int_type(to_int_type(*aStr1),
+                       to_int_type(static_cast<char_type>(*aStr2)))) {
+        return to_int_type(*aStr1) -
+               to_int_type(static_cast<char_type>(*aStr2));
+      }
+    }
+
+    return 0;
+  }
+
+  // this version assumes that s2 is null-terminated and s1 has length n.
+  // if s1 is shorter than s2 then we return -1; if s1 is longer than s2,
+  // we return 1.
+  static int
+  compareASCIINullTerminated(const char_type* aStr1, size_t aN,
+                             const char* aStr2)
+  {
+    for (; aN--; ++aStr1, ++aStr2) {
+      if (!*aStr2) {
+        return 1;
+      }
+      NS_ASSERTION(!(*aStr2 & ~0x7F), "Unexpected non-ASCII character");
+      if (!eq_int_type(to_int_type(*aStr1),
+                       to_int_type(static_cast<char_type>(*aStr2)))) {
+        return to_int_type(*aStr1) -
+               to_int_type(static_cast<char_type>(*aStr2));
+      }
+    }
+
+    if (*aStr2) {
+      return -1;
+    }
+
+    return 0;
+  }
+
+  /**
+   * Convert c to its lower-case form, but only if c is in the ASCII
+   * range. Otherwise leave it alone.
+   */
+  static char_type
+  ASCIIToLower(char_type aChar)
+  {
+    if (aChar >= 'A' && aChar <= 'Z') {
+      return char_type(aChar + ('a' - 'A'));
+    }
+
+    return aChar;
+  }
+
+  static int
+  compareLowerCaseToASCII(const char_type* aStr1, const char* aStr2, size_t aN)
+  {
+    for (; aN--; ++aStr1, ++aStr2) {
+      NS_ASSERTION(!(*aStr2 & ~0x7F), "Unexpected non-ASCII character");
+      NS_ASSERTION(!(*aStr2 >= 'A' && *aStr2 <= 'Z'),
+                   "Unexpected uppercase character");
+      char_type lower_s1 = ASCIIToLower(*aStr1);
+      if (lower_s1 != static_cast<char_type>(*aStr2)) {
+        return to_int_type(lower_s1) -
+               to_int_type(static_cast<char_type>(*aStr2));
+      }
+    }
+
+    return 0;
+  }
+
+  // this version assumes that s2 is null-terminated and s1 has length n.
+  // if s1 is shorter than s2 then we return -1; if s1 is longer than s2,
+  // we return 1.
+  static int
+  compareLowerCaseToASCIINullTerminated(const char_type* aStr1,
+                                        size_t aN, const char* aStr2)
+  {
+    for (; aN--; ++aStr1, ++aStr2) {
+      if (!*aStr2) {
+        return 1;
+      }
+      NS_ASSERTION(!(*aStr2 & ~0x7F), "Unexpected non-ASCII character");
+      NS_ASSERTION(!(*aStr2 >= 'A' && *aStr2 <= 'Z'),
+                   "Unexpected uppercase character");
+      char_type lower_s1 = ASCIIToLower(*aStr1);
+      if (lower_s1 != static_cast<char_type>(*aStr2)) {
+        return to_int_type(lower_s1) -
+               to_int_type(static_cast<char_type>(*aStr2));
+      }
+    }
+
+    if (*aStr2) {
+      return -1;
+    }
+
+    return 0;
+  }
+
+  static size_t
+  length(const char_type* aStr)
+  {
+    size_t result = 0;
+    while (!eq(*aStr++, char_type(0))) {
+      ++result;
+    }
+    return result;
+  }
+
+  static const char_type*
+  find(const char_type* aStr, size_t aN, char_type aChar)
+  {
+    while (aN--) {
+      if (eq(*aStr, aChar)) {
+        return aStr;
+      }
+      ++aStr;
+    }
+
+    return 0;
+  }
+};
+
+template <>
+struct nsCharTraits<char>
+{
+  typedef char           char_type;
+  typedef unsigned char  unsigned_char_type;
+  typedef char16_t      incompatible_char_type;
+
+  static char_type* const sEmptyBuffer;
+
+  static void
+  assign(char_type& aLhs, char_type aRhs)
+  {
+    aLhs = aRhs;
+  }
+
+
+  // integer representation of characters:
+
+  typedef int int_type;
+
+  static char_type
+  to_char_type(int_type aChar)
+  {
+    return char_type(aChar);
+  }
+
+  static int_type
+  to_int_type(char_type aChar)
+  {
+    return int_type(static_cast<unsigned_char_type>(aChar));
+  }
+
+  static bool
+  eq_int_type(int_type aLhs, int_type aRhs)
+  {
+    return aLhs == aRhs;
+  }
+
+
+  // |char_type| comparisons:
+
+  static bool eq(char_type aLhs, char_type aRhs)
+  {
+    return aLhs == aRhs;
+  }
+
+  static bool
+  lt(char_type aLhs, char_type aRhs)
+  {
+    return aLhs < aRhs;
+  }
+
+
+  // operations on s[n] arrays:
+
+  static char_type*
+  move(char_type* aStr1, const char_type* aStr2, size_t aN)
+  {
+    return static_cast<char_type*>(memmove(aStr1, aStr2,
+                                           aN * sizeof(char_type)));
+  }
+
+  static char_type*
+  copy(char_type* aStr1, const char_type* aStr2, size_t aN)
+  {
+    return static_cast<char_type*>(memcpy(aStr1, aStr2,
+                                          aN * sizeof(char_type)));
+  }
+
+  static char_type*
+  copyASCII(char_type* aStr1, const char* aStr2, size_t aN)
+  {
+    return copy(aStr1, aStr2, aN);
+  }
+
+  static char_type*
+  assign(char_type* aStr, size_t aN, char_type aChar)
+  {
+    return static_cast<char_type*>(memset(aStr, to_int_type(aChar), aN));
+  }
+
+  static int
+  compare(const char_type* aStr1, const char_type* aStr2, size_t aN)
+  {
+    return memcmp(aStr1, aStr2, aN);
+  }
+
+  static int
+  compareASCII(const char_type* aStr1, const char* aStr2, size_t aN)
+  {
+#ifdef DEBUG
+    for (size_t i = 0; i < aN; ++i) {
+      NS_ASSERTION(!(aStr2[i] & ~0x7F), "Unexpected non-ASCII character");
+    }
+#endif
+    return compare(aStr1, aStr2, aN);
+  }
+
+  // this version assumes that s2 is null-terminated and s1 has length n.
+  // if s1 is shorter than s2 then we return -1; if s1 is longer than s2,
+  // we return 1.
+  static int
+  compareASCIINullTerminated(const char_type* aStr1, size_t aN,
+                             const char* aStr2)
+  {
+    // can't use strcmp here because we don't want to stop when aStr1
+    // contains a null
+    for (; aN--; ++aStr1, ++aStr2) {
+      if (!*aStr2) {
+        return 1;
+      }
+      NS_ASSERTION(!(*aStr2 & ~0x7F), "Unexpected non-ASCII character");
+      if (*aStr1 != *aStr2) {
+        return to_int_type(*aStr1) - to_int_type(*aStr2);
+      }
+    }
+
+    if (*aStr2) {
+      return -1;
+    }
+
+    return 0;
+  }
+
+  /**
+   * Convert c to its lower-case form, but only if c is ASCII.
+   */
+  static char_type
+  ASCIIToLower(char_type aChar)
+  {
+    if (aChar >= 'A' && aChar <= 'Z') {
+      return char_type(aChar + ('a' - 'A'));
+    }
+
+    return aChar;
+  }
+
+  static int
+  compareLowerCaseToASCII(const char_type* aStr1, const char* aStr2, size_t aN)
+  {
+    for (; aN--; ++aStr1, ++aStr2) {
+      NS_ASSERTION(!(*aStr2 & ~0x7F), "Unexpected non-ASCII character");
+      NS_ASSERTION(!(*aStr2 >= 'A' && *aStr2 <= 'Z'),
+                   "Unexpected uppercase character");
+      char_type lower_s1 = ASCIIToLower(*aStr1);
+      if (lower_s1 != *aStr2) {
+        return to_int_type(lower_s1) - to_int_type(*aStr2);
+      }
+    }
+    return 0;
+  }
+
+  // this version assumes that s2 is null-terminated and s1 has length n.
+  // if s1 is shorter than s2 then we return -1; if s1 is longer than s2,
+  // we return 1.
+  static int
+  compareLowerCaseToASCIINullTerminated(const char_type* aStr1, size_t aN,
+                                        const char* aStr2)
+  {
+    for (; aN--; ++aStr1, ++aStr2) {
+      if (!*aStr2) {
+        return 1;
+      }
+      NS_ASSERTION(!(*aStr2 & ~0x7F), "Unexpected non-ASCII character");
+      NS_ASSERTION(!(*aStr2 >= 'A' && *aStr2 <= 'Z'),
+                   "Unexpected uppercase character");
+      char_type lower_s1 = ASCIIToLower(*aStr1);
+      if (lower_s1 != *aStr2) {
+        return to_int_type(lower_s1) - to_int_type(*aStr2);
+      }
+    }
+
+    if (*aStr2) {
+      return -1;
+    }
+
+    return 0;
+  }
+
+  static size_t
+  length(const char_type* aStr)
+  {
+    return strlen(aStr);
+  }
+
+  static const char_type*
+  find(const char_type* aStr, size_t aN, char_type aChar)
+  {
+    return reinterpret_cast<const char_type*>(memchr(aStr, to_int_type(aChar),
+                                                     aN));
+  }
+};
+
+template <class InputIterator>
+struct nsCharSourceTraits
+{
+  typedef typename InputIterator::difference_type difference_type;
+
+  static uint32_t
+  readable_distance(const InputIterator& aFirst, const InputIterator& aLast)
+  {
+    // assumes single fragment
+    return uint32_t(aLast.get() - aFirst.get());
+  }
+
+  static const typename InputIterator::value_type*
+  read(const InputIterator& aIter)
+  {
+    return aIter.get();
+  }
+
+  static void
+  advance(InputIterator& aStr, difference_type aN)
+  {
+    aStr.advance(aN);
+  }
+};
+
+template <class CharT>
+struct nsCharSourceTraits<CharT*>
+{
+  typedef ptrdiff_t difference_type;
+
+  static uint32_t
+  readable_distance(CharT* aStr)
+  {
+    return uint32_t(nsCharTraits<CharT>::length(aStr));
+    // return numeric_limits<uint32_t>::max();
+  }
+
+  static uint32_t
+  readable_distance(CharT* aFirst, CharT* aLast)
+  {
+    return uint32_t(aLast - aFirst);
+  }
+
+  static const CharT*
+  read(CharT* aStr)
+  {
+    return aStr;
+  }
+
+  static void
+  advance(CharT*& aStr, difference_type aN)
+  {
+    aStr += aN;
+  }
+};
+
+template <class OutputIterator>
+struct nsCharSinkTraits
+{
+  static void
+  write(OutputIterator& aIter, const typename OutputIterator::value_type* aStr,
+        uint32_t aN)
+  {
+    aIter.write(aStr, aN);
+  }
+};
+
+template <class CharT>
+struct nsCharSinkTraits<CharT*>
+{
+  static void
+  write(CharT*& aIter, const CharT* aStr, uint32_t aN)
+  {
+    nsCharTraits<CharT>::move(aIter, aStr, aN);
+    aIter += aN;
+  }
+};
+
+#endif // !defined(nsCharTraits_h___)
diff --git a/xpcom/string/nsDependentString.cpp b/xpcom/string/nsDependentString.cpp
new file mode 100644
index 000000000..52240d17b
--- /dev/null
+++ b/xpcom/string/nsDependentString.cpp
@@ -0,0 +1,18 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsDependentString.h"
+#include "nsAlgorithm.h"
+
+// define nsDependentString
+#include "string-template-def-unichar.h"
+#include "nsTDependentString.cpp"
+#include "string-template-undef.h"
+
+// define nsDependentCString
+#include "string-template-def-char.h"
+#include "nsTDependentString.cpp"
+#include "string-template-undef.h"
diff --git a/xpcom/string/nsDependentString.h b/xpcom/string/nsDependentString.h
new file mode 100644
index 000000000..20b5997ef
--- /dev/null
+++ b/xpcom/string/nsDependentString.h
@@ -0,0 +1,23 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsDependentString_h___
+#define nsDependentString_h___
+
+#include "nsString.h"
+#include "nsDebug.h"
+
+// declare nsDependentString
+#include "string-template-def-unichar.h"
+#include "nsTDependentString.h"
+#include "string-template-undef.h"
+
+// declare nsDependentCString
+#include "string-template-def-char.h"
+#include "nsTDependentString.h"
+#include "string-template-undef.h"
+
+#endif /* !defined(nsDependentString_h___) */
diff --git a/xpcom/string/nsDependentSubstring.cpp b/xpcom/string/nsDependentSubstring.cpp
new file mode 100644
index 000000000..721cf8f6a
--- /dev/null
+++ b/xpcom/string/nsDependentSubstring.cpp
@@ -0,0 +1,18 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsDependentSubstring.h"
+#include "nsAlgorithm.h"
+
+// define nsDependentSubstring
+#include "string-template-def-unichar.h"
+#include "nsTDependentSubstring.cpp"
+#include "string-template-undef.h"
+
+// define nsDependentCSubstring
+#include "string-template-def-char.h"
+#include "nsTDependentSubstring.cpp"
+#include "string-template-undef.h"
diff --git a/xpcom/string/nsDependentSubstring.h b/xpcom/string/nsDependentSubstring.h
new file mode 100644
index 000000000..078b8ab54
--- /dev/null
+++ b/xpcom/string/nsDependentSubstring.h
@@ -0,0 +1,22 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsDependentSubstring_h___
+#define nsDependentSubstring_h___
+
+#include "nsSubstring.h"
+
+// declare nsDependentSubstring
+#include "string-template-def-unichar.h"
+#include "nsTDependentSubstring.h"
+#include "string-template-undef.h"
+
+// declare nsDependentCSubstring
+#include "string-template-def-char.h"
+#include "nsTDependentSubstring.h"
+#include "string-template-undef.h"
+
+#endif /* !defined(nsDependentSubstring_h___) */
diff --git a/xpcom/string/nsEmbedString.h b/xpcom/string/nsEmbedString.h
new file mode 100644
index 000000000..caedd50cd
--- /dev/null
+++ b/xpcom/string/nsEmbedString.h
@@ -0,0 +1,18 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsEmbedString_h___
+#define nsEmbedString_h___
+
+#include "nsStringAPI.h"
+
+/**
+ * compatibility
+ */
+typedef nsString  nsEmbedString;
+typedef nsCString nsEmbedCString;
+
+#endif
diff --git a/xpcom/string/nsLiteralString.h b/xpcom/string/nsLiteralString.h
new file mode 100644
index 000000000..4a0b39107
--- /dev/null
+++ b/xpcom/string/nsLiteralString.h
@@ -0,0 +1,37 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsLiteralString_h___
+#define nsLiteralString_h___
+
+#include "nscore.h"
+#include "nsString.h"
+
+// declare nsLiteralString
+#include "string-template-def-unichar.h"
+#include "nsTLiteralString.h"
+#include "string-template-undef.h"
+
+// declare nsLiteralCString
+#include "string-template-def-char.h"
+#include "nsTLiteralString.h"
+#include "string-template-undef.h"
+
+#include "mozilla/Char16.h"
+
+#define NS_MULTILINE_LITERAL_STRING(s)            static_cast<const nsLiteralString&>(nsLiteralString(s))
+#define NS_MULTILINE_LITERAL_STRING_INIT(n,s)     n(s)
+#define NS_NAMED_MULTILINE_LITERAL_STRING(n,s)    const nsLiteralString n(s)
+
+#define NS_LITERAL_STRING(s)                      static_cast<const nsLiteralString&>(nsLiteralString(u"" s))
+#define NS_LITERAL_STRING_INIT(n,s)               n(u"" s)
+#define NS_NAMED_LITERAL_STRING(n,s)              const nsLiteralString n(u"" s)
+
+#define NS_LITERAL_CSTRING(s)                     static_cast<const nsLiteralCString&>(nsLiteralCString("" s))
+#define NS_LITERAL_CSTRING_INIT(n,s)              n("" s)
+#define NS_NAMED_LITERAL_CSTRING(n,s)             const nsLiteralCString n("" s)
+
+#endif /* !defined(nsLiteralString_h___) */
diff --git a/xpcom/string/nsPrintfCString.h b/xpcom/string/nsPrintfCString.h
new file mode 100644
index 000000000..ce90ec497
--- /dev/null
+++ b/xpcom/string/nsPrintfCString.h
@@ -0,0 +1,42 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsPrintfCString_h___
+#define nsPrintfCString_h___
+
+#include "nsString.h"
+
+/**
+ * nsPrintfCString lets you create a nsCString using a printf-style format
+ * string.  For example:
+ *
+ *   NS_WARNING(nsPrintfCString("Unexpected value: %f", 13.917).get());
+ *
+ * nsPrintfCString has a small built-in auto-buffer.  For larger strings, it
+ * will allocate on the heap.
+ *
+ * See also nsCString::AppendPrintf().
+ */
+class nsPrintfCString : public nsFixedCString
+{
+  typedef nsCString string_type;
+
+public:
+  explicit nsPrintfCString(const char_type* aFormat, ...)
+    : nsFixedCString(mLocalBuffer, kLocalBufferSize, 0)
+  {
+    va_list ap;
+    va_start(ap, aFormat);
+    AppendPrintf(aFormat, ap);
+    va_end(ap);
+  }
+
+private:
+  static const uint32_t kLocalBufferSize = 16;
+  char_type mLocalBuffer[kLocalBufferSize];
+};
+
+#endif // !defined(nsPrintfCString_h___)
diff --git a/xpcom/string/nsPromiseFlatString.cpp b/xpcom/string/nsPromiseFlatString.cpp
new file mode 100644
index 000000000..e66d2ef9f
--- /dev/null
+++ b/xpcom/string/nsPromiseFlatString.cpp
@@ -0,0 +1,17 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsPromiseFlatString.h"
+
+// define nsPromiseFlatString
+#include "string-template-def-unichar.h"
+#include "nsTPromiseFlatString.cpp"
+#include "string-template-undef.h"
+
+// define nsPromiseFlatCString
+#include "string-template-def-char.h"
+#include "nsTPromiseFlatString.cpp"
+#include "string-template-undef.h"
diff --git a/xpcom/string/nsPromiseFlatString.h b/xpcom/string/nsPromiseFlatString.h
new file mode 100644
index 000000000..a025bfd26
--- /dev/null
+++ b/xpcom/string/nsPromiseFlatString.h
@@ -0,0 +1,22 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsPromiseFlatString_h___
+#define nsPromiseFlatString_h___
+
+#include "nsString.h"
+
+// declare nsPromiseFlatString
+#include "string-template-def-unichar.h"
+#include "nsTPromiseFlatString.h"
+#include "string-template-undef.h"
+
+// declare nsPromiseFlatCString
+#include "string-template-def-char.h"
+#include "nsTPromiseFlatString.h"
+#include "string-template-undef.h"
+
+#endif /* !defined(nsPromiseFlatString_h___) */
diff --git a/xpcom/string/nsReadableUtils.cpp b/xpcom/string/nsReadableUtils.cpp
new file mode 100644
index 000000000..524b1d7fe
--- /dev/null
+++ b/xpcom/string/nsReadableUtils.cpp
@@ -0,0 +1,1383 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsReadableUtils.h"
+#include "nsReadableUtilsImpl.h"
+
+#include <algorithm>
+
+#include "mozilla/CheckedInt.h"
+
+#include "nscore.h"
+#include "nsMemory.h"
+#include "nsString.h"
+#include "nsTArray.h"
+#include "nsUTF8Utils.h"
+
+using mozilla::IsASCII;
+
+/**
+ * Fallback implementation for finding the first non-ASCII character in a
+ * UTF-16 string.
+ */
+static inline int32_t
+FirstNonASCIIUnvectorized(const char16_t* aBegin, const char16_t* aEnd)
+{
+  typedef mozilla::NonASCIIParameters<sizeof(size_t)> p;
+  const size_t kMask = p::mask();
+  const uintptr_t kAlignMask = p::alignMask();
+  const size_t kNumUnicharsPerWord = p::numUnicharsPerWord();
+
+  const char16_t* idx = aBegin;
+
+  // Align ourselves to a word boundary.
+  for (; idx != aEnd && ((uintptr_t(idx) & kAlignMask) != 0); idx++) {
+    if (!IsASCII(*idx)) {
+      return idx - aBegin;
+    }
+  }
+
+  // Check one word at a time.
+  const char16_t* wordWalkEnd = mozilla::aligned(aEnd, kAlignMask);
+  for (; idx != wordWalkEnd; idx += kNumUnicharsPerWord) {
+    const size_t word = *reinterpret_cast<const size_t*>(idx);
+    if (word & kMask) {
+      return idx - aBegin;
+    }
+  }
+
+  // Take care of the remainder one character at a time.
+  for (; idx != aEnd; idx++) {
+    if (!IsASCII(*idx)) {
+      return idx - aBegin;
+    }
+  }
+
+  return -1;
+}
+
+/*
+ * This function returns -1 if all characters in str are ASCII characters.
+ * Otherwise, it returns a value less than or equal to the index of the first
+ * ASCII character in str. For example, if first non-ASCII character is at
+ * position 25, it may return 25, 24, or 16. But it guarantees
+ * there are only ASCII characters before returned value.
+ */
+static inline int32_t
+FirstNonASCII(const char16_t* aBegin, const char16_t* aEnd)
+{
+#ifdef MOZILLA_MAY_SUPPORT_SSE2
+  if (mozilla::supports_sse2()) {
+    return mozilla::SSE2::FirstNonASCII(aBegin, aEnd);
+  }
+#endif
+
+  return FirstNonASCIIUnvectorized(aBegin, aEnd);
+}
+
+void
+LossyCopyUTF16toASCII(const nsAString& aSource, nsACString& aDest)
+{
+  aDest.Truncate();
+  LossyAppendUTF16toASCII(aSource, aDest);
+}
+
+void
+CopyASCIItoUTF16(const nsACString& aSource, nsAString& aDest)
+{
+  aDest.Truncate();
+  AppendASCIItoUTF16(aSource, aDest);
+}
+
+void
+LossyCopyUTF16toASCII(const char16ptr_t aSource, nsACString& aDest)
+{
+  aDest.Truncate();
+  if (aSource) {
+    LossyAppendUTF16toASCII(nsDependentString(aSource), aDest);
+  }
+}
+
+void
+CopyASCIItoUTF16(const char* aSource, nsAString& aDest)
+{
+  aDest.Truncate();
+  if (aSource) {
+    AppendASCIItoUTF16(nsDependentCString(aSource), aDest);
+  }
+}
+
+void
+CopyUTF16toUTF8(const nsAString& aSource, nsACString& aDest)
+{
+  if (!CopyUTF16toUTF8(aSource, aDest, mozilla::fallible)) {
+    // Note that this may wildly underestimate the allocation that failed, as
+    // we report the length of aSource as UTF-16 instead of UTF-8.
+    aDest.AllocFailed(aDest.Length() + aSource.Length());
+  }
+}
+
+bool
+CopyUTF16toUTF8(const nsAString& aSource, nsACString& aDest,
+                const mozilla::fallible_t& aFallible)
+{
+  aDest.Truncate();
+  if (!AppendUTF16toUTF8(aSource, aDest, aFallible)) {
+    return false;
+  }
+  return true;
+}
+
+void
+CopyUTF8toUTF16(const nsACString& aSource, nsAString& aDest)
+{
+  aDest.Truncate();
+  AppendUTF8toUTF16(aSource, aDest);
+}
+
+void
+CopyUTF16toUTF8(const char16ptr_t aSource, nsACString& aDest)
+{
+  aDest.Truncate();
+  AppendUTF16toUTF8(aSource, aDest);
+}
+
+void
+CopyUTF8toUTF16(const char* aSource, nsAString& aDest)
+{
+  aDest.Truncate();
+  AppendUTF8toUTF16(aSource, aDest);
+}
+
+void
+LossyAppendUTF16toASCII(const nsAString& aSource, nsACString& aDest)
+{
+  uint32_t old_dest_length = aDest.Length();
+  aDest.SetLength(old_dest_length + aSource.Length());
+
+  nsAString::const_iterator fromBegin, fromEnd;
+
+  nsACString::iterator dest;
+  aDest.BeginWriting(dest);
+
+  dest.advance(old_dest_length);
+
+  // right now, this won't work on multi-fragment destinations
+  LossyConvertEncoding16to8 converter(dest.get());
+
+  copy_string(aSource.BeginReading(fromBegin), aSource.EndReading(fromEnd),
+              converter);
+}
+
+void
+AppendASCIItoUTF16(const nsACString& aSource, nsAString& aDest)
+{
+  if (!AppendASCIItoUTF16(aSource, aDest, mozilla::fallible)) {
+    aDest.AllocFailed(aDest.Length() + aSource.Length());
+  }
+}
+
+bool
+AppendASCIItoUTF16(const nsACString& aSource, nsAString& aDest,
+                   const mozilla::fallible_t& aFallible)
+{
+  uint32_t old_dest_length = aDest.Length();
+  if (!aDest.SetLength(old_dest_length + aSource.Length(),
+                       aFallible)) {
+    return false;
+  }
+
+  nsACString::const_iterator fromBegin, fromEnd;
+
+  nsAString::iterator dest;
+  aDest.BeginWriting(dest);
+
+  dest.advance(old_dest_length);
+
+  // right now, this won't work on multi-fragment destinations
+  LossyConvertEncoding8to16 converter(dest.get());
+
+  copy_string(aSource.BeginReading(fromBegin), aSource.EndReading(fromEnd),
+              converter);
+  return true;
+}
+
+void
+LossyAppendUTF16toASCII(const char16ptr_t aSource, nsACString& aDest)
+{
+  if (aSource) {
+    LossyAppendUTF16toASCII(nsDependentString(aSource), aDest);
+  }
+}
+
+bool
+AppendASCIItoUTF16(const char* aSource, nsAString& aDest, const mozilla::fallible_t& aFallible)
+{
+  if (aSource) {
+    return AppendASCIItoUTF16(nsDependentCString(aSource), aDest, aFallible);
+  }
+
+  return true;
+}
+
+void
+AppendASCIItoUTF16(const char* aSource, nsAString& aDest)
+{
+  if (aSource) {
+    AppendASCIItoUTF16(nsDependentCString(aSource), aDest);
+  }
+}
+
+void
+AppendUTF16toUTF8(const nsAString& aSource, nsACString& aDest)
+{
+  if (!AppendUTF16toUTF8(aSource, aDest, mozilla::fallible)) {
+    // Note that this may wildly underestimate the allocation that failed, as
+    // we report the length of aSource as UTF-16 instead of UTF-8.
+    aDest.AllocFailed(aDest.Length() + aSource.Length());
+  }
+}
+
+bool
+AppendUTF16toUTF8(const nsAString& aSource, nsACString& aDest,
+                  const mozilla::fallible_t& aFallible)
+{
+  // At 16 characters analysis showed better performance of both the all ASCII
+  // and non-ASCII cases, so we limit calling |FirstNonASCII| to strings of
+  // that length.
+  const nsAString::size_type kFastPathMinLength = 16;
+
+  int32_t firstNonASCII = 0;
+  if (aSource.Length() >= kFastPathMinLength) {
+    firstNonASCII = FirstNonASCII(aSource.BeginReading(), aSource.EndReading());
+  }
+
+  if (firstNonASCII == -1) {
+    // This is all ASCII, we can use the more efficient lossy append.
+    mozilla::CheckedInt<nsACString::size_type> new_length(aSource.Length());
+    new_length += aDest.Length();
+
+    if (!new_length.isValid() ||
+        !aDest.SetCapacity(new_length.value(), aFallible)) {
+      return false;
+    }
+
+    LossyAppendUTF16toASCII(aSource, aDest);
+    return true;
+  }
+
+  nsAString::const_iterator source_start, source_end;
+  CalculateUTF8Size calculator;
+  aSource.BeginReading(source_start);
+  aSource.EndReading(source_end);
+
+  // Skip the characters that we know are single byte.
+  source_start.advance(firstNonASCII);
+
+  copy_string(source_start,
+              source_end, calculator);
+
+  // Include the ASCII characters that were skipped in the count.
+  size_t count = calculator.Size() + firstNonASCII;
+
+  if (count) {
+    auto old_dest_length = aDest.Length();
+    // Grow the buffer if we need to.
+    mozilla::CheckedInt<nsACString::size_type> new_length(count);
+    new_length += old_dest_length;
+
+    if (!new_length.isValid() ||
+        !aDest.SetLength(new_length.value(), aFallible)) {
+      return false;
+    }
+
+    // All ready? Time to convert
+
+    nsAString::const_iterator ascii_end;
+    aSource.BeginReading(ascii_end);
+
+    if (firstNonASCII >= static_cast<int32_t>(kFastPathMinLength)) {
+      // Use the more efficient lossy converter for the ASCII portion.
+      LossyConvertEncoding16to8 lossy_converter(
+          aDest.BeginWriting() + old_dest_length);
+      nsAString::const_iterator ascii_start;
+      aSource.BeginReading(ascii_start);
+      ascii_end.advance(firstNonASCII);
+
+      copy_string(ascii_start, ascii_end, lossy_converter);
+    } else {
+      // Not using the lossy shortcut, we need to include the leading ASCII
+      // chars.
+      firstNonASCII = 0;
+    }
+
+    ConvertUTF16toUTF8 converter(
+        aDest.BeginWriting() + old_dest_length + firstNonASCII);
+    copy_string(ascii_end,
+                aSource.EndReading(source_end), converter);
+
+    NS_ASSERTION(converter.Size() == count - firstNonASCII,
+                 "Unexpected disparity between CalculateUTF8Size and "
+                 "ConvertUTF16toUTF8");
+  }
+
+  return true;
+}
+
+void
+AppendUTF8toUTF16(const nsACString& aSource, nsAString& aDest)
+{
+  if (!AppendUTF8toUTF16(aSource, aDest, mozilla::fallible)) {
+    aDest.AllocFailed(aDest.Length() + aSource.Length());
+  }
+}
+
+bool
+AppendUTF8toUTF16(const nsACString& aSource, nsAString& aDest,
+                  const mozilla::fallible_t& aFallible)
+{
+  nsACString::const_iterator source_start, source_end;
+  CalculateUTF8Length calculator;
+  copy_string(aSource.BeginReading(source_start),
+              aSource.EndReading(source_end), calculator);
+
+  uint32_t count = calculator.Length();
+
+  // Avoid making the string mutable if we're appending an empty string
+  if (count) {
+    uint32_t old_dest_length = aDest.Length();
+
+    // Grow the buffer if we need to.
+    if (!aDest.SetLength(old_dest_length + count, aFallible)) {
+      return false;
+    }
+
+    // All ready? Time to convert
+
+    ConvertUTF8toUTF16 converter(aDest.BeginWriting() + old_dest_length);
+    copy_string(aSource.BeginReading(source_start),
+                aSource.EndReading(source_end), converter);
+
+    NS_ASSERTION(converter.ErrorEncountered() ||
+                 converter.Length() == count,
+                 "CalculateUTF8Length produced the wrong length");
+
+    if (converter.ErrorEncountered()) {
+      NS_ERROR("Input wasn't UTF8 or incorrect length was calculated");
+      aDest.SetLength(old_dest_length);
+    }
+  }
+
+  return true;
+}
+
+void
+AppendUTF16toUTF8(const char16ptr_t aSource, nsACString& aDest)
+{
+  if (aSource) {
+    AppendUTF16toUTF8(nsDependentString(aSource), aDest);
+  }
+}
+
+void
+AppendUTF8toUTF16(const char* aSource, nsAString& aDest)
+{
+  if (aSource) {
+    AppendUTF8toUTF16(nsDependentCString(aSource), aDest);
+  }
+}
+
+
+/**
+ * A helper function that allocates a buffer of the desired character type big enough to hold a copy of the supplied string (plus a zero terminator).
+ *
+ * @param aSource an string you will eventually be making a copy of
+ * @return a new buffer (of the type specified by the second parameter) which you must free with |free|.
+ *
+ */
+template <class FromStringT, class ToCharT>
+inline
+ToCharT*
+AllocateStringCopy(const FromStringT& aSource, ToCharT*)
+{
+  return static_cast<ToCharT*>(moz_xmalloc(
+    (aSource.Length() + 1) * sizeof(ToCharT)));
+}
+
+
+char*
+ToNewCString(const nsAString& aSource)
+{
+  char* result = AllocateStringCopy(aSource, (char*)0);
+  if (!result) {
+    return nullptr;
+  }
+
+  nsAString::const_iterator fromBegin, fromEnd;
+  LossyConvertEncoding16to8 converter(result);
+  copy_string(aSource.BeginReading(fromBegin), aSource.EndReading(fromEnd),
+              converter).write_terminator();
+  return result;
+}
+
+char*
+ToNewUTF8String(const nsAString& aSource, uint32_t* aUTF8Count)
+{
+  nsAString::const_iterator start, end;
+  CalculateUTF8Size calculator;
+  copy_string(aSource.BeginReading(start), aSource.EndReading(end),
+              calculator);
+
+  if (aUTF8Count) {
+    *aUTF8Count = calculator.Size();
+  }
+
+  char* result = static_cast<char*>
+                 (moz_xmalloc(calculator.Size() + 1));
+  if (!result) {
+    return nullptr;
+  }
+
+  ConvertUTF16toUTF8 converter(result);
+  copy_string(aSource.BeginReading(start), aSource.EndReading(end),
+              converter).write_terminator();
+  NS_ASSERTION(calculator.Size() == converter.Size(), "length mismatch");
+
+  return result;
+}
+
+char*
+ToNewCString(const nsACString& aSource)
+{
+  // no conversion needed, just allocate a buffer of the correct length and copy into it
+
+  char* result = AllocateStringCopy(aSource, (char*)0);
+  if (!result) {
+    return nullptr;
+  }
+
+  nsACString::const_iterator fromBegin, fromEnd;
+  char* toBegin = result;
+  *copy_string(aSource.BeginReading(fromBegin), aSource.EndReading(fromEnd),
+               toBegin) = char(0);
+  return result;
+}
+
+char16_t*
+ToNewUnicode(const nsAString& aSource)
+{
+  // no conversion needed, just allocate a buffer of the correct length and copy into it
+
+  char16_t* result = AllocateStringCopy(aSource, (char16_t*)0);
+  if (!result) {
+    return nullptr;
+  }
+
+  nsAString::const_iterator fromBegin, fromEnd;
+  char16_t* toBegin = result;
+  *copy_string(aSource.BeginReading(fromBegin), aSource.EndReading(fromEnd),
+               toBegin) = char16_t(0);
+  return result;
+}
+
+char16_t*
+ToNewUnicode(const nsACString& aSource)
+{
+  char16_t* result = AllocateStringCopy(aSource, (char16_t*)0);
+  if (!result) {
+    return nullptr;
+  }
+
+  nsACString::const_iterator fromBegin, fromEnd;
+  LossyConvertEncoding8to16 converter(result);
+  copy_string(aSource.BeginReading(fromBegin), aSource.EndReading(fromEnd),
+              converter).write_terminator();
+  return result;
+}
+
+uint32_t
+CalcUTF8ToUnicodeLength(const nsACString& aSource)
+{
+  nsACString::const_iterator start, end;
+  CalculateUTF8Length calculator;
+  copy_string(aSource.BeginReading(start), aSource.EndReading(end),
+              calculator);
+  return calculator.Length();
+}
+
+char16_t*
+UTF8ToUnicodeBuffer(const nsACString& aSource, char16_t* aBuffer,
+                    uint32_t* aUTF16Count)
+{
+  nsACString::const_iterator start, end;
+  ConvertUTF8toUTF16 converter(aBuffer);
+  copy_string(aSource.BeginReading(start),
+              aSource.EndReading(end),
+              converter).write_terminator();
+  if (aUTF16Count) {
+    *aUTF16Count = converter.Length();
+  }
+  return aBuffer;
+}
+
+char16_t*
+UTF8ToNewUnicode(const nsACString& aSource, uint32_t* aUTF16Count)
+{
+  const uint32_t length = CalcUTF8ToUnicodeLength(aSource);
+  const size_t buffer_size = (length + 1) * sizeof(char16_t);
+  char16_t* buffer = static_cast<char16_t*>(moz_xmalloc(buffer_size));
+  if (!buffer) {
+    return nullptr;
+  }
+
+  uint32_t copied;
+  UTF8ToUnicodeBuffer(aSource, buffer, &copied);
+  NS_ASSERTION(length == copied, "length mismatch");
+
+  if (aUTF16Count) {
+    *aUTF16Count = copied;
+  }
+  return buffer;
+}
+
+char16_t*
+CopyUnicodeTo(const nsAString& aSource, uint32_t aSrcOffset, char16_t* aDest,
+              uint32_t aLength)
+{
+  nsAString::const_iterator fromBegin, fromEnd;
+  char16_t* toBegin = aDest;
+  copy_string(aSource.BeginReading(fromBegin).advance(int32_t(aSrcOffset)),
+              aSource.BeginReading(fromEnd).advance(int32_t(aSrcOffset + aLength)),
+              toBegin);
+  return aDest;
+}
+
+void
+CopyUnicodeTo(const nsAString::const_iterator& aSrcStart,
+              const nsAString::const_iterator& aSrcEnd,
+              nsAString& aDest)
+{
+  aDest.SetLength(Distance(aSrcStart, aSrcEnd));
+
+  nsAString::char_iterator dest = aDest.BeginWriting();
+  nsAString::const_iterator fromBegin(aSrcStart);
+
+  copy_string(fromBegin, aSrcEnd, dest);
+}
+
+void
+AppendUnicodeTo(const nsAString::const_iterator& aSrcStart,
+                const nsAString::const_iterator& aSrcEnd,
+                nsAString& aDest)
+{
+  uint32_t oldLength = aDest.Length();
+  aDest.SetLength(oldLength + Distance(aSrcStart, aSrcEnd));
+
+  nsAString::char_iterator dest = aDest.BeginWriting() + oldLength;
+  nsAString::const_iterator fromBegin(aSrcStart);
+
+  copy_string(fromBegin, aSrcEnd, dest);
+}
+
+bool
+IsASCII(const nsAString& aString)
+{
+  static const char16_t NOT_ASCII = char16_t(~0x007F);
+
+
+  // Don't want to use |copy_string| for this task, since we can stop at the first non-ASCII character
+
+  nsAString::const_iterator iter, done_reading;
+  aString.BeginReading(iter);
+  aString.EndReading(done_reading);
+
+  const char16_t* c = iter.get();
+  const char16_t* end = done_reading.get();
+
+  while (c < end) {
+    if (*c++ & NOT_ASCII) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool
+IsASCII(const nsACString& aString)
+{
+  static const char NOT_ASCII = char(~0x7F);
+
+
+  // Don't want to use |copy_string| for this task, since we can stop at the first non-ASCII character
+
+  nsACString::const_iterator iter, done_reading;
+  aString.BeginReading(iter);
+  aString.EndReading(done_reading);
+
+  const char* c = iter.get();
+  const char* end = done_reading.get();
+
+  while (c < end) {
+    if (*c++ & NOT_ASCII) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool
+IsUTF8(const nsACString& aString, bool aRejectNonChar)
+{
+  nsReadingIterator<char> done_reading;
+  aString.EndReading(done_reading);
+
+  int32_t state = 0;
+  bool overlong = false;
+  bool surrogate = false;
+  bool nonchar = false;
+  uint16_t olupper = 0; // overlong byte upper bound.
+  uint16_t slower = 0;  // surrogate byte lower bound.
+
+  nsReadingIterator<char> iter;
+  aString.BeginReading(iter);
+
+  const char* ptr = iter.get();
+  const char* end = done_reading.get();
+  while (ptr < end) {
+    uint8_t c;
+
+    if (0 == state) {
+      c = *ptr++;
+
+      if (UTF8traits::isASCII(c)) {
+        continue;
+      }
+
+      if (c <= 0xC1) { // [80-BF] where not expected, [C0-C1] for overlong.
+        return false;
+      } else if (UTF8traits::is2byte(c)) {
+        state = 1;
+      } else if (UTF8traits::is3byte(c)) {
+        state = 2;
+        if (c == 0xE0) { // to exclude E0[80-9F][80-BF]
+          overlong = true;
+          olupper = 0x9F;
+        } else if (c == 0xED) { // ED[A0-BF][80-BF] : surrogate codepoint
+          surrogate = true;
+          slower = 0xA0;
+        } else if (c == 0xEF) { // EF BF [BE-BF] : non-character
+          nonchar = true;
+        }
+      } else if (c <= 0xF4) { // XXX replace /w UTF8traits::is4byte when it's updated to exclude [F5-F7].(bug 199090)
+        state = 3;
+        nonchar = true;
+        if (c == 0xF0) { // to exclude F0[80-8F][80-BF]{2}
+          overlong = true;
+          olupper = 0x8F;
+        } else if (c == 0xF4) { // to exclude F4[90-BF][80-BF]
+          // actually not surrogates but codepoints beyond 0x10FFFF
+          surrogate = true;
+          slower = 0x90;
+        }
+      } else {
+        return false;  // Not UTF-8 string
+      }
+    }
+
+    if (nonchar && !aRejectNonChar) {
+      nonchar = false;
+    }
+
+    while (ptr < end && state) {
+      c = *ptr++;
+      --state;
+
+      // non-character : EF BF [BE-BF] or F[0-7] [89AB]F BF [BE-BF]
+      if (nonchar &&
+          ((!state && c < 0xBE) ||
+           (state == 1 && c != 0xBF)  ||
+           (state == 2 && 0x0F != (0x0F & c)))) {
+        nonchar = false;
+      }
+
+      if (!UTF8traits::isInSeq(c) || (overlong && c <= olupper) ||
+          (surrogate && slower <= c) || (nonchar && !state)) {
+        return false;  // Not UTF-8 string
+      }
+
+      overlong = surrogate = false;
+    }
+  }
+  return !state; // state != 0 at the end indicates an invalid UTF-8 seq.
+}
+
+/**
+ * A character sink for in-place case conversion.
+ */
+class ConvertToUpperCase
+{
+public:
+  typedef char value_type;
+
+  uint32_t
+  write(const char* aSource, uint32_t aSourceLength)
+  {
+    char* cp = const_cast<char*>(aSource);
+    const char* end = aSource + aSourceLength;
+    while (cp != end) {
+      char ch = *cp;
+      if (ch >= 'a' && ch <= 'z') {
+        *cp = ch - ('a' - 'A');
+      }
+      ++cp;
+    }
+    return aSourceLength;
+  }
+};
+
+void
+ToUpperCase(nsCSubstring& aCString)
+{
+  ConvertToUpperCase converter;
+  char* start;
+  converter.write(aCString.BeginWriting(start), aCString.Length());
+}
+
+/**
+ * A character sink for copying with case conversion.
+ */
+class CopyToUpperCase
+{
+public:
+  typedef char value_type;
+
+  explicit CopyToUpperCase(nsACString::iterator& aDestIter,
+                           const nsACString::iterator& aEndIter)
+    : mIter(aDestIter)
+    , mEnd(aEndIter)
+  {
+  }
+
+  uint32_t
+  write(const char* aSource, uint32_t aSourceLength)
+  {
+    uint32_t len = XPCOM_MIN(uint32_t(mEnd - mIter), aSourceLength);
+    char* cp = mIter.get();
+    const char* end = aSource + len;
+    while (aSource != end) {
+      char ch = *aSource;
+      if ((ch >= 'a') && (ch <= 'z')) {
+        *cp = ch - ('a' - 'A');
+      } else {
+        *cp = ch;
+      }
+      ++aSource;
+      ++cp;
+    }
+    mIter.advance(len);
+    return len;
+  }
+
+protected:
+  nsACString::iterator& mIter;
+  const nsACString::iterator& mEnd;
+};
+
+void
+ToUpperCase(const nsACString& aSource, nsACString& aDest)
+{
+  nsACString::const_iterator fromBegin, fromEnd;
+  nsACString::iterator toBegin, toEnd;
+  aDest.SetLength(aSource.Length());
+
+  CopyToUpperCase converter(aDest.BeginWriting(toBegin), aDest.EndWriting(toEnd));
+  copy_string(aSource.BeginReading(fromBegin), aSource.EndReading(fromEnd),
+              converter);
+}
+
+/**
+ * A character sink for case conversion.
+ */
+class ConvertToLowerCase
+{
+public:
+  typedef char value_type;
+
+  uint32_t
+  write(const char* aSource, uint32_t aSourceLength)
+  {
+    char* cp = const_cast<char*>(aSource);
+    const char* end = aSource + aSourceLength;
+    while (cp != end) {
+      char ch = *cp;
+      if ((ch >= 'A') && (ch <= 'Z')) {
+        *cp = ch + ('a' - 'A');
+      }
+      ++cp;
+    }
+    return aSourceLength;
+  }
+};
+
+void
+ToLowerCase(nsCSubstring& aCString)
+{
+  ConvertToLowerCase converter;
+  char* start;
+  converter.write(aCString.BeginWriting(start), aCString.Length());
+}
+
+/**
+ * A character sink for copying with case conversion.
+ */
+class CopyToLowerCase
+{
+public:
+  typedef char value_type;
+
+  explicit CopyToLowerCase(nsACString::iterator& aDestIter,
+                           const nsACString::iterator& aEndIter)
+    : mIter(aDestIter)
+    , mEnd(aEndIter)
+  {
+  }
+
+  uint32_t
+  write(const char* aSource, uint32_t aSourceLength)
+  {
+    uint32_t len = XPCOM_MIN(uint32_t(mEnd - mIter), aSourceLength);
+    char* cp = mIter.get();
+    const char* end = aSource + len;
+    while (aSource != end) {
+      char ch = *aSource;
+      if ((ch >= 'A') && (ch <= 'Z')) {
+        *cp = ch + ('a' - 'A');
+      } else {
+        *cp = ch;
+      }
+      ++aSource;
+      ++cp;
+    }
+    mIter.advance(len);
+    return len;
+  }
+
+protected:
+  nsACString::iterator& mIter;
+  const nsACString::iterator& mEnd;
+};
+
+void
+ToLowerCase(const nsACString& aSource, nsACString& aDest)
+{
+  nsACString::const_iterator fromBegin, fromEnd;
+  nsACString::iterator toBegin, toEnd;
+  aDest.SetLength(aSource.Length());
+
+  CopyToLowerCase converter(aDest.BeginWriting(toBegin), aDest.EndWriting(toEnd));
+  copy_string(aSource.BeginReading(fromBegin), aSource.EndReading(fromEnd),
+              converter);
+}
+
+bool
+ParseString(const nsACString& aSource, char aDelimiter,
+            nsTArray<nsCString>& aArray)
+{
+  nsACString::const_iterator start, end;
+  aSource.BeginReading(start);
+  aSource.EndReading(end);
+
+  uint32_t oldLength = aArray.Length();
+
+  for (;;) {
+    nsACString::const_iterator delimiter = start;
+    FindCharInReadable(aDelimiter, delimiter, end);
+
+    if (delimiter != start) {
+      if (!aArray.AppendElement(Substring(start, delimiter))) {
+        aArray.RemoveElementsAt(oldLength, aArray.Length() - oldLength);
+        return false;
+      }
+    }
+
+    if (delimiter == end) {
+      break;
+    }
+    start = ++delimiter;
+    if (start == end) {
+      break;
+    }
+  }
+
+  return true;
+}
+
+template <class StringT, class IteratorT, class Comparator>
+bool
+FindInReadable_Impl(const StringT& aPattern, IteratorT& aSearchStart,
+                    IteratorT& aSearchEnd, const Comparator& aCompare)
+{
+  bool found_it = false;
+
+  // only bother searching at all if we're given a non-empty range to search
+  if (aSearchStart != aSearchEnd) {
+    IteratorT aPatternStart, aPatternEnd;
+    aPattern.BeginReading(aPatternStart);
+    aPattern.EndReading(aPatternEnd);
+
+    // outer loop keeps searching till we find it or run out of string to search
+    while (!found_it) {
+      // fast inner loop (that's what it's called, not what it is) looks for a potential match
+      while (aSearchStart != aSearchEnd &&
+             aCompare(aPatternStart.get(), aSearchStart.get(), 1, 1)) {
+        ++aSearchStart;
+      }
+
+      // if we broke out of the `fast' loop because we're out of string ... we're done: no match
+      if (aSearchStart == aSearchEnd) {
+        break;
+      }
+
+      // otherwise, we're at a potential match, let's see if we really hit one
+      IteratorT testPattern(aPatternStart);
+      IteratorT testSearch(aSearchStart);
+
+      // slow inner loop verifies the potential match (found by the `fast' loop) at the current position
+      for (;;) {
+        // we already compared the first character in the outer loop,
+        //  so we'll advance before the next comparison
+        ++testPattern;
+        ++testSearch;
+
+        // if we verified all the way to the end of the pattern, then we found it!
+        if (testPattern == aPatternEnd) {
+          found_it = true;
+          aSearchEnd = testSearch; // return the exact found range through the parameters
+          break;
+        }
+
+        // if we got to end of the string we're searching before we hit the end of the
+        //  pattern, we'll never find what we're looking for
+        if (testSearch == aSearchEnd) {
+          aSearchStart = aSearchEnd;
+          break;
+        }
+
+        // else if we mismatched ... it's time to advance to the next search position
+        //  and get back into the `fast' loop
+        if (aCompare(testPattern.get(), testSearch.get(), 1, 1)) {
+          ++aSearchStart;
+          break;
+        }
+      }
+    }
+  }
+
+  return found_it;
+}
+
+/**
+ * This searches the entire string from right to left, and returns the first match found, if any.
+ */
+template <class StringT, class IteratorT, class Comparator>
+bool
+RFindInReadable_Impl(const StringT& aPattern, IteratorT& aSearchStart,
+                     IteratorT& aSearchEnd, const Comparator& aCompare)
+{
+  IteratorT patternStart, patternEnd, searchEnd = aSearchEnd;
+  aPattern.BeginReading(patternStart);
+  aPattern.EndReading(patternEnd);
+
+  // Point to the last character in the pattern
+  --patternEnd;
+  // outer loop keeps searching till we run out of string to search
+  while (aSearchStart != searchEnd) {
+    // Point to the end position of the next possible match
+    --searchEnd;
+
+    // Check last character, if a match, explore further from here
+    if (aCompare(patternEnd.get(), searchEnd.get(), 1, 1) == 0) {
+      // We're at a potential match, let's see if we really hit one
+      IteratorT testPattern(patternEnd);
+      IteratorT testSearch(searchEnd);
+
+      // inner loop verifies the potential match at the current position
+      do {
+        // if we verified all the way to the end of the pattern, then we found it!
+        if (testPattern == patternStart) {
+          aSearchStart = testSearch;  // point to start of match
+          aSearchEnd = ++searchEnd;   // point to end of match
+          return true;
+        }
+
+        // if we got to end of the string we're searching before we hit the end of the
+        //  pattern, we'll never find what we're looking for
+        if (testSearch == aSearchStart) {
+          aSearchStart = aSearchEnd;
+          return false;
+        }
+
+        // test previous character for a match
+        --testPattern;
+        --testSearch;
+      } while (aCompare(testPattern.get(), testSearch.get(), 1, 1) == 0);
+    }
+  }
+
+  aSearchStart = aSearchEnd;
+  return false;
+}
+
+bool
+FindInReadable(const nsAString& aPattern,
+               nsAString::const_iterator& aSearchStart,
+               nsAString::const_iterator& aSearchEnd,
+               const nsStringComparator& aComparator)
+{
+  return FindInReadable_Impl(aPattern, aSearchStart, aSearchEnd, aComparator);
+}
+
+bool
+FindInReadable(const nsACString& aPattern,
+               nsACString::const_iterator& aSearchStart,
+               nsACString::const_iterator& aSearchEnd,
+               const nsCStringComparator& aComparator)
+{
+  return FindInReadable_Impl(aPattern, aSearchStart, aSearchEnd, aComparator);
+}
+
+bool
+CaseInsensitiveFindInReadable(const nsACString& aPattern,
+                              nsACString::const_iterator& aSearchStart,
+                              nsACString::const_iterator& aSearchEnd)
+{
+  return FindInReadable_Impl(aPattern, aSearchStart, aSearchEnd,
+                             nsCaseInsensitiveCStringComparator());
+}
+
+bool
+RFindInReadable(const nsAString& aPattern,
+                nsAString::const_iterator& aSearchStart,
+                nsAString::const_iterator& aSearchEnd,
+                const nsStringComparator& aComparator)
+{
+  return RFindInReadable_Impl(aPattern, aSearchStart, aSearchEnd, aComparator);
+}
+
+bool
+RFindInReadable(const nsACString& aPattern,
+                nsACString::const_iterator& aSearchStart,
+                nsACString::const_iterator& aSearchEnd,
+                const nsCStringComparator& aComparator)
+{
+  return RFindInReadable_Impl(aPattern, aSearchStart, aSearchEnd, aComparator);
+}
+
+bool
+FindCharInReadable(char16_t aChar, nsAString::const_iterator& aSearchStart,
+                   const nsAString::const_iterator& aSearchEnd)
+{
+  int32_t fragmentLength = aSearchEnd.get() - aSearchStart.get();
+
+  const char16_t* charFoundAt =
+    nsCharTraits<char16_t>::find(aSearchStart.get(), fragmentLength, aChar);
+  if (charFoundAt) {
+    aSearchStart.advance(charFoundAt - aSearchStart.get());
+    return true;
+  }
+
+  aSearchStart.advance(fragmentLength);
+  return false;
+}
+
+bool
+FindCharInReadable(char aChar, nsACString::const_iterator& aSearchStart,
+                   const nsACString::const_iterator& aSearchEnd)
+{
+  int32_t fragmentLength = aSearchEnd.get() - aSearchStart.get();
+
+  const char* charFoundAt =
+    nsCharTraits<char>::find(aSearchStart.get(), fragmentLength, aChar);
+  if (charFoundAt) {
+    aSearchStart.advance(charFoundAt - aSearchStart.get());
+    return true;
+  }
+
+  aSearchStart.advance(fragmentLength);
+  return false;
+}
+
+uint32_t
+CountCharInReadable(const nsAString& aStr, char16_t aChar)
+{
+  uint32_t count = 0;
+  nsAString::const_iterator begin, end;
+
+  aStr.BeginReading(begin);
+  aStr.EndReading(end);
+
+  while (begin != end) {
+    if (*begin == aChar) {
+      ++count;
+    }
+    ++begin;
+  }
+
+  return count;
+}
+
+uint32_t
+CountCharInReadable(const nsACString& aStr, char aChar)
+{
+  uint32_t count = 0;
+  nsACString::const_iterator begin, end;
+
+  aStr.BeginReading(begin);
+  aStr.EndReading(end);
+
+  while (begin != end) {
+    if (*begin == aChar) {
+      ++count;
+    }
+    ++begin;
+  }
+
+  return count;
+}
+
+bool
+StringBeginsWith(const nsAString& aSource, const nsAString& aSubstring)
+{
+  nsAString::size_type src_len = aSource.Length(),
+                       sub_len = aSubstring.Length();
+  if (sub_len > src_len) {
+    return false;
+  }
+  return Substring(aSource, 0, sub_len).Equals(aSubstring);
+}
+
+bool
+StringBeginsWith(const nsAString& aSource, const nsAString& aSubstring,
+                 const nsStringComparator& aComparator)
+{
+  nsAString::size_type src_len = aSource.Length(),
+                       sub_len = aSubstring.Length();
+  if (sub_len > src_len) {
+    return false;
+  }
+  return Substring(aSource, 0, sub_len).Equals(aSubstring, aComparator);
+}
+
+bool
+StringBeginsWith(const nsACString& aSource, const nsACString& aSubstring)
+{
+  nsACString::size_type src_len = aSource.Length(),
+                        sub_len = aSubstring.Length();
+  if (sub_len > src_len) {
+    return false;
+  }
+  return Substring(aSource, 0, sub_len).Equals(aSubstring);
+}
+
+bool
+StringBeginsWith(const nsACString& aSource, const nsACString& aSubstring,
+                 const nsCStringComparator& aComparator)
+{
+  nsACString::size_type src_len = aSource.Length(),
+                        sub_len = aSubstring.Length();
+  if (sub_len > src_len) {
+    return false;
+  }
+  return Substring(aSource, 0, sub_len).Equals(aSubstring, aComparator);
+}
+
+bool
+StringEndsWith(const nsAString& aSource, const nsAString& aSubstring)
+{
+  nsAString::size_type src_len = aSource.Length(),
+                       sub_len = aSubstring.Length();
+  if (sub_len > src_len) {
+    return false;
+  }
+  return Substring(aSource, src_len - sub_len, sub_len).Equals(aSubstring);
+}
+
+bool
+StringEndsWith(const nsAString& aSource, const nsAString& aSubstring,
+               const nsStringComparator& aComparator)
+{
+  nsAString::size_type src_len = aSource.Length(),
+                       sub_len = aSubstring.Length();
+  if (sub_len > src_len) {
+    return false;
+  }
+  return Substring(aSource, src_len - sub_len, sub_len).Equals(aSubstring,
+                                                               aComparator);
+}
+
+bool
+StringEndsWith(const nsACString& aSource, const nsACString& aSubstring)
+{
+  nsACString::size_type src_len = aSource.Length(),
+                        sub_len = aSubstring.Length();
+  if (sub_len > src_len) {
+    return false;
+  }
+  return Substring(aSource, src_len - sub_len, sub_len).Equals(aSubstring);
+}
+
+bool
+StringEndsWith(const nsACString& aSource, const nsACString& aSubstring,
+               const nsCStringComparator& aComparator)
+{
+  nsACString::size_type src_len = aSource.Length(),
+                        sub_len = aSubstring.Length();
+  if (sub_len > src_len) {
+    return false;
+  }
+  return Substring(aSource, src_len - sub_len, sub_len).Equals(aSubstring,
+                                                               aComparator);
+}
+
+
+
+static const char16_t empty_buffer[1] = { '\0' };
+
+const nsAFlatString&
+EmptyString()
+{
+  static const nsDependentString sEmpty(empty_buffer);
+
+  return sEmpty;
+}
+
+const nsAFlatCString&
+EmptyCString()
+{
+  static const nsDependentCString sEmpty((const char*)empty_buffer);
+
+  return sEmpty;
+}
+
+const nsAFlatString&
+NullString()
+{
+  static const nsXPIDLString sNull;
+
+  return sNull;
+}
+
+const nsAFlatCString&
+NullCString()
+{
+  static const nsXPIDLCString sNull;
+
+  return sNull;
+}
+
+int32_t
+CompareUTF8toUTF16(const nsASingleFragmentCString& aUTF8String,
+                   const nsASingleFragmentString& aUTF16String)
+{
+  static const uint32_t NOT_ASCII = uint32_t(~0x7F);
+
+  const char* u8;
+  const char* u8end;
+  aUTF8String.BeginReading(u8);
+  aUTF8String.EndReading(u8end);
+
+  const char16_t* u16;
+  const char16_t* u16end;
+  aUTF16String.BeginReading(u16);
+  aUTF16String.EndReading(u16end);
+
+  while (u8 != u8end && u16 != u16end) {
+    // Cast away the signedness of *u8 to prevent signextension when
+    // converting to uint32_t
+    uint32_t c8_32 = (uint8_t)*u8;
+
+    if (c8_32 & NOT_ASCII) {
+      bool err;
+      c8_32 = UTF8CharEnumerator::NextChar(&u8, u8end, &err);
+      if (err) {
+        return INT32_MIN;
+      }
+
+      uint32_t c16_32 = UTF16CharEnumerator::NextChar(&u16, u16end);
+      // The above UTF16CharEnumerator::NextChar() calls can
+      // fail, but if it does for anything other than no data to
+      // look at (which can't happen here), it returns the
+      // Unicode replacement character 0xFFFD for the invalid
+      // data they were fed. Ignore that error and treat invalid
+      // UTF16 as 0xFFFD.
+      //
+      // This matches what our UTF16 to UTF8 conversion code
+      // does, and thus a UTF8 string that came from an invalid
+      // UTF16 string will compare equal to the invalid UTF16
+      // string it came from. Same is true for any other UTF16
+      // string differs only in the invalid part of the string.
+
+      if (c8_32 != c16_32) {
+        return c8_32 < c16_32 ? -1 : 1;
+      }
+    } else {
+      if (c8_32 != *u16) {
+        return c8_32 > *u16 ? 1 : -1;
+      }
+
+      ++u8;
+      ++u16;
+    }
+  }
+
+  if (u8 != u8end) {
+    // We get to the end of the UTF16 string, but no to the end of
+    // the UTF8 string. The UTF8 string is longer than the UTF16
+    // string
+
+    return 1;
+  }
+
+  if (u16 != u16end) {
+    // We get to the end of the UTF8 string, but no to the end of
+    // the UTF16 string. The UTF16 string is longer than the UTF8
+    // string
+
+    return -1;
+  }
+
+  // The two strings match.
+
+  return 0;
+}
+
+void
+AppendUCS4ToUTF16(const uint32_t aSource, nsAString& aDest)
+{
+  NS_ASSERTION(IS_VALID_CHAR(aSource), "Invalid UCS4 char");
+  if (IS_IN_BMP(aSource)) {
+    aDest.Append(char16_t(aSource));
+  } else {
+    aDest.Append(H_SURROGATE(aSource));
+    aDest.Append(L_SURROGATE(aSource));
+  }
+}
+
+extern "C" {
+
+void Gecko_AppendUTF16toCString(nsACString* aThis, const nsAString* aOther)
+{
+  AppendUTF16toUTF8(*aOther, *aThis);
+}
+
+void Gecko_AppendUTF8toString(nsAString* aThis, const nsACString* aOther)
+{
+  AppendUTF8toUTF16(*aOther, *aThis);
+}
+
+}
diff --git a/xpcom/string/nsReadableUtils.h b/xpcom/string/nsReadableUtils.h
new file mode 100644
index 000000000..24824d927
--- /dev/null
+++ b/xpcom/string/nsReadableUtils.h
@@ -0,0 +1,428 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+// IWYU pragma: private, include "nsString.h"
+
+#ifndef nsReadableUtils_h___
+#define nsReadableUtils_h___
+
+/**
+ * I guess all the routines in this file are all mis-named.
+ * According to our conventions, they should be |NS_xxx|.
+ */
+
+#include "mozilla/Assertions.h"
+#include "nsAString.h"
+
+#include "nsTArrayForwardDeclare.h"
+
+inline size_t
+Distance(const nsReadingIterator<char16_t>& aStart,
+         const nsReadingIterator<char16_t>& aEnd)
+{
+  MOZ_ASSERT(aStart.get() <= aEnd.get());
+  return static_cast<size_t>(aEnd.get() - aStart.get());
+}
+inline size_t
+Distance(const nsReadingIterator<char>& aStart,
+         const nsReadingIterator<char>& aEnd)
+{
+  MOZ_ASSERT(aStart.get() <= aEnd.get());
+  return static_cast<size_t>(aEnd.get() - aStart.get());
+}
+
+void LossyCopyUTF16toASCII(const nsAString& aSource, nsACString& aDest);
+void CopyASCIItoUTF16(const nsACString& aSource, nsAString& aDest);
+
+void LossyCopyUTF16toASCII(const char16ptr_t aSource, nsACString& aDest);
+void CopyASCIItoUTF16(const char* aSource, nsAString& aDest);
+
+void CopyUTF16toUTF8(const nsAString& aSource, nsACString& aDest);
+MOZ_MUST_USE bool CopyUTF16toUTF8(const nsAString& aSource, nsACString& aDest,
+                                  const mozilla::fallible_t&);
+void CopyUTF8toUTF16(const nsACString& aSource, nsAString& aDest);
+
+void CopyUTF16toUTF8(const char16ptr_t aSource, nsACString& aDest);
+void CopyUTF8toUTF16(const char* aSource, nsAString& aDest);
+
+void LossyAppendUTF16toASCII(const nsAString& aSource, nsACString& aDest);
+void AppendASCIItoUTF16(const nsACString& aSource, nsAString& aDest);
+MOZ_MUST_USE bool AppendASCIItoUTF16(const nsACString& aSource,
+                                     nsAString& aDest,
+                                     const mozilla::fallible_t&);
+
+void LossyAppendUTF16toASCII(const char16ptr_t aSource, nsACString& aDest);
+MOZ_MUST_USE bool AppendASCIItoUTF16(const char* aSource,
+                                     nsAString& aDest,
+                                     const mozilla::fallible_t&);
+void AppendASCIItoUTF16(const char* aSource, nsAString& aDest);
+
+void AppendUTF16toUTF8(const nsAString& aSource, nsACString& aDest);
+MOZ_MUST_USE bool AppendUTF16toUTF8(const nsAString& aSource,
+                                    nsACString& aDest,
+                                    const mozilla::fallible_t&);
+void AppendUTF8toUTF16(const nsACString& aSource, nsAString& aDest);
+MOZ_MUST_USE bool AppendUTF8toUTF16(const nsACString& aSource,
+                                    nsAString& aDest,
+                                    const mozilla::fallible_t&);
+
+void AppendUTF16toUTF8(const char16ptr_t aSource, nsACString& aDest);
+void AppendUTF8toUTF16(const char* aSource, nsAString& aDest);
+
+/**
+ * Returns a new |char| buffer containing a zero-terminated copy of |aSource|.
+ *
+ * Allocates and returns a new |char| buffer which you must free with |free|.
+ * Performs a lossy encoding conversion by chopping 16-bit wide characters down to 8-bits wide while copying |aSource| to your new buffer.
+ * This conversion is not well defined; but it reproduces legacy string behavior.
+ * The new buffer is zero-terminated, but that may not help you if |aSource| contains embedded nulls.
+ *
+ * @param aSource a 16-bit wide string
+ * @return a new |char| buffer you must free with |free|.
+ */
+char* ToNewCString(const nsAString& aSource);
+
+
+/**
+ * Returns a new |char| buffer containing a zero-terminated copy of |aSource|.
+ *
+ * Allocates and returns a new |char| buffer which you must free with |free|.
+ * The new buffer is zero-terminated, but that may not help you if |aSource| contains embedded nulls.
+ *
+ * @param aSource an 8-bit wide string
+ * @return a new |char| buffer you must free with |free|.
+ */
+char* ToNewCString(const nsACString& aSource);
+
+/**
+ * Returns a new |char| buffer containing a zero-terminated copy of |aSource|.
+ *
+ * Allocates and returns a new |char| buffer which you must free with
+ * |free|.
+ * Performs an encoding conversion from a UTF-16 string to a UTF-8 string
+ * copying |aSource| to your new buffer.
+ * The new buffer is zero-terminated, but that may not help you if |aSource|
+ * contains embedded nulls.
+ *
+ * @param aSource a UTF-16 string (made of char16_t's)
+ * @param aUTF8Count the number of 8-bit units that was returned
+ * @return a new |char| buffer you must free with |free|.
+ */
+
+char* ToNewUTF8String(const nsAString& aSource, uint32_t* aUTF8Count = nullptr);
+
+
+/**
+ * Returns a new |char16_t| buffer containing a zero-terminated copy of
+ * |aSource|.
+ *
+ * Allocates and returns a new |char16_t| buffer which you must free with
+ * |free|.
+ * The new buffer is zero-terminated, but that may not help you if |aSource|
+ * contains embedded nulls.
+ *
+ * @param aSource a UTF-16 string
+ * @return a new |char16_t| buffer you must free with |free|.
+ */
+char16_t* ToNewUnicode(const nsAString& aSource);
+
+
+/**
+ * Returns a new |char16_t| buffer containing a zero-terminated copy of |aSource|.
+ *
+ * Allocates and returns a new |char16_t| buffer which you must free with |free|.
+ * Performs an encoding conversion by 0-padding 8-bit wide characters up to 16-bits wide while copying |aSource| to your new buffer.
+ * This conversion is not well defined; but it reproduces legacy string behavior.
+ * The new buffer is zero-terminated, but that may not help you if |aSource| contains embedded nulls.
+ *
+ * @param aSource an 8-bit wide string (a C-string, NOT UTF-8)
+ * @return a new |char16_t| buffer you must free with |free|.
+ */
+char16_t* ToNewUnicode(const nsACString& aSource);
+
+/**
+ * Returns the required length for a char16_t buffer holding
+ * a copy of aSource, using UTF-8 to UTF-16 conversion.
+ * The length does NOT include any space for zero-termination.
+ *
+ * @param aSource an 8-bit wide string, UTF-8 encoded
+ * @return length of UTF-16 encoded string copy, not zero-terminated
+ */
+uint32_t CalcUTF8ToUnicodeLength(const nsACString& aSource);
+
+/**
+ * Copies the source string into the specified buffer, converting UTF-8 to
+ * UTF-16 in the process. The conversion is well defined for valid UTF-8
+ * strings.
+ * The copied string will be zero-terminated! Any embedded nulls will be
+ * copied nonetheless. It is the caller's responsiblity to ensure the buffer
+ * is large enough to hold the string copy plus one char16_t for
+ * zero-termination!
+ *
+ * @see CalcUTF8ToUnicodeLength( const nsACString& )
+ * @see UTF8ToNewUnicode( const nsACString&, uint32_t* )
+ *
+ * @param aSource an 8-bit wide string, UTF-8 encoded
+ * @param aBuffer the buffer holding the converted string copy
+ * @param aUTF16Count receiving optionally the number of 16-bit units that
+ *                    were copied
+ * @return aBuffer pointer, for convenience
+ */
+char16_t* UTF8ToUnicodeBuffer(const nsACString& aSource,
+                              char16_t* aBuffer,
+                              uint32_t* aUTF16Count = nullptr);
+
+/**
+ * Returns a new |char16_t| buffer containing a zero-terminated copy
+ * of |aSource|.
+ *
+ * Allocates and returns a new |char| buffer which you must free with
+ * |free|.  Performs an encoding conversion from UTF-8 to UTF-16
+ * while copying |aSource| to your new buffer.  This conversion is well defined
+ * for a valid UTF-8 string.  The new buffer is zero-terminated, but that
+ * may not help you if |aSource| contains embedded nulls.
+ *
+ * @param aSource an 8-bit wide string, UTF-8 encoded
+ * @param aUTF16Count the number of 16-bit units that was returned
+ * @return a new |char16_t| buffer you must free with |free|.
+ *         (UTF-16 encoded)
+ */
+char16_t* UTF8ToNewUnicode(const nsACString& aSource,
+                           uint32_t* aUTF16Count = nullptr);
+
+/**
+ * Copies |aLength| 16-bit code units from the start of |aSource| to the
+ * |char16_t| buffer |aDest|.
+ *
+ * After this operation |aDest| is not null terminated.
+ *
+ * @param aSource a UTF-16 string
+ * @param aSrcOffset start offset in the source string
+ * @param aDest a |char16_t| buffer
+ * @param aLength the number of 16-bit code units to copy
+ * @return pointer to destination buffer - identical to |aDest|
+ */
+char16_t* CopyUnicodeTo(const nsAString& aSource,
+                        uint32_t aSrcOffset,
+                        char16_t* aDest,
+                        uint32_t aLength);
+
+
+/**
+ * Copies 16-bit characters between iterators |aSrcStart| and
+ * |aSrcEnd| to the writable string |aDest|. Similar to the
+ * |nsString::Mid| method.
+ *
+ * After this operation |aDest| is not null terminated.
+ *
+ * @param aSrcStart start source iterator
+ * @param aSrcEnd end source iterator
+ * @param aDest destination for the copy
+ */
+void CopyUnicodeTo(const nsAString::const_iterator& aSrcStart,
+                   const nsAString::const_iterator& aSrcEnd,
+                   nsAString& aDest);
+
+/**
+ * Appends 16-bit characters between iterators |aSrcStart| and
+ * |aSrcEnd| to the writable string |aDest|.
+ *
+ * After this operation |aDest| is not null terminated.
+ *
+ * @param aSrcStart start source iterator
+ * @param aSrcEnd end source iterator
+ * @param aDest destination for the copy
+ */
+void AppendUnicodeTo(const nsAString::const_iterator& aSrcStart,
+                     const nsAString::const_iterator& aSrcEnd,
+                     nsAString& aDest);
+
+/**
+ * Returns |true| if |aString| contains only ASCII characters, that is, characters in the range (0x00, 0x7F).
+ *
+ * @param aString a 16-bit wide string to scan
+ */
+bool IsASCII(const nsAString& aString);
+
+/**
+ * Returns |true| if |aString| contains only ASCII characters, that is, characters in the range (0x00, 0x7F).
+ *
+ * @param aString a 8-bit wide string to scan
+ */
+bool IsASCII(const nsACString& aString);
+
+/**
+ * Returns |true| if |aString| is a valid UTF-8 string.
+ * XXX This is not bullet-proof and nor an all-purpose UTF-8 validator.
+ * It is mainly written to replace and roughly equivalent to
+ *
+ *    str.Equals(NS_ConvertUTF16toUTF8(NS_ConvertUTF8toUTF16(str)))
+ *
+ * (see bug 191541)
+ * As such,  it does not check for non-UTF-8 7bit encodings such as
+ * ISO-2022-JP and HZ.
+ *
+ * It rejects sequences with the following errors:
+ *
+ * byte sequences that cannot be decoded into characters according to
+ *   UTF-8's rules (including cases where the input is part of a valid
+ *   UTF-8 sequence but starts or ends mid-character)
+ * overlong sequences (i.e., cases where a character was encoded
+ *   non-canonically by using more bytes than necessary)
+ * surrogate codepoints (i.e., the codepoints reserved for
+     representing astral characters in UTF-16)
+ * codepoints above the unicode range (i.e., outside the first 17
+ *   planes; higher than U+10FFFF), in accordance with
+ *   http://tools.ietf.org/html/rfc3629
+ * when aRejectNonChar is true (the default), any codepoint whose low
+ *   16 bits are 0xFFFE or 0xFFFF
+
+ *
+ * @param aString an 8-bit wide string to scan
+ * @param aRejectNonChar a boolean to control the rejection of utf-8
+ *        non characters
+ */
+bool IsUTF8(const nsACString& aString, bool aRejectNonChar = true);
+
+bool ParseString(const nsACString& aAstring, char aDelimiter,
+                 nsTArray<nsCString>& aArray);
+
+/**
+ * Converts case in place in the argument string.
+ */
+void ToUpperCase(nsACString&);
+
+void ToLowerCase(nsACString&);
+
+void ToUpperCase(nsCSubstring&);
+
+void ToLowerCase(nsCSubstring&);
+
+/**
+ * Converts case from string aSource to aDest.
+ */
+void ToUpperCase(const nsACString& aSource, nsACString& aDest);
+
+void ToLowerCase(const nsACString& aSource, nsACString& aDest);
+
+/**
+ * Finds the leftmost occurrence of |aPattern|, if any in the range |aSearchStart|..|aSearchEnd|.
+ *
+ * Returns |true| if a match was found, and adjusts |aSearchStart| and |aSearchEnd| to
+ * point to the match.  If no match was found, returns |false| and makes |aSearchStart == aSearchEnd|.
+ *
+ * Currently, this is equivalent to the O(m*n) implementation previously on |ns[C]String|.
+ * If we need something faster, then we can implement that later.
+ */
+
+bool FindInReadable(const nsAString& aPattern, nsAString::const_iterator&,
+                    nsAString::const_iterator&,
+                    const nsStringComparator& = nsDefaultStringComparator());
+bool FindInReadable(const nsACString& aPattern, nsACString::const_iterator&,
+                    nsACString::const_iterator&,
+                    const nsCStringComparator& = nsDefaultCStringComparator());
+
+/* sometimes we don't care about where the string was, just that we
+ * found it or not */
+inline bool
+FindInReadable(const nsAString& aPattern, const nsAString& aSource,
+               const nsStringComparator& aCompare = nsDefaultStringComparator())
+{
+  nsAString::const_iterator start, end;
+  aSource.BeginReading(start);
+  aSource.EndReading(end);
+  return FindInReadable(aPattern, start, end, aCompare);
+}
+
+inline bool
+FindInReadable(const nsACString& aPattern, const nsACString& aSource,
+               const nsCStringComparator& aCompare = nsDefaultCStringComparator())
+{
+  nsACString::const_iterator start, end;
+  aSource.BeginReading(start);
+  aSource.EndReading(end);
+  return FindInReadable(aPattern, start, end, aCompare);
+}
+
+
+bool CaseInsensitiveFindInReadable(const nsACString& aPattern,
+                                   nsACString::const_iterator&,
+                                   nsACString::const_iterator&);
+
+/**
+ * Finds the rightmost occurrence of |aPattern|
+ * Returns |true| if a match was found, and adjusts |aSearchStart| and |aSearchEnd| to
+ * point to the match.  If no match was found, returns |false| and makes |aSearchStart == aSearchEnd|.
+ *
+ */
+bool RFindInReadable(const nsAString& aPattern, nsAString::const_iterator&,
+                     nsAString::const_iterator&,
+                     const nsStringComparator& = nsDefaultStringComparator());
+bool RFindInReadable(const nsACString& aPattern, nsACString::const_iterator&,
+                     nsACString::const_iterator&,
+                     const nsCStringComparator& = nsDefaultCStringComparator());
+
+/**
+* Finds the leftmost occurrence of |aChar|, if any in the range
+* |aSearchStart|..|aSearchEnd|.
+*
+* Returns |true| if a match was found, and adjusts |aSearchStart| to
+* point to the match.  If no match was found, returns |false| and
+* makes |aSearchStart == aSearchEnd|.
+*/
+bool FindCharInReadable(char16_t aChar, nsAString::const_iterator& aSearchStart,
+                        const nsAString::const_iterator& aSearchEnd);
+bool FindCharInReadable(char aChar, nsACString::const_iterator& aSearchStart,
+                        const nsACString::const_iterator& aSearchEnd);
+
+/**
+* Finds the number of occurences of |aChar| in the string |aStr|
+*/
+uint32_t CountCharInReadable(const nsAString& aStr,
+                             char16_t aChar);
+uint32_t CountCharInReadable(const nsACString& aStr,
+                             char aChar);
+
+bool StringBeginsWith(const nsAString& aSource, const nsAString& aSubstring);
+bool StringBeginsWith(const nsAString& aSource, const nsAString& aSubstring,
+                      const nsStringComparator& aComparator);
+bool StringBeginsWith(const nsACString& aSource, const nsACString& aSubstring);
+bool StringBeginsWith(const nsACString& aSource, const nsACString& aSubstring,
+                      const nsCStringComparator& aComparator);
+bool StringEndsWith(const nsAString& aSource, const nsAString& aSubstring);
+bool StringEndsWith(const nsAString& aSource, const nsAString& aSubstring,
+                    const nsStringComparator& aComparator);
+bool StringEndsWith(const nsACString& aSource, const nsACString& aSubstring);
+bool StringEndsWith(const nsACString& aSource, const nsACString& aSubstring,
+                    const nsCStringComparator& aComparator);
+
+const nsAFlatString& EmptyString();
+const nsAFlatCString& EmptyCString();
+
+const nsAFlatString& NullString();
+const nsAFlatCString& NullCString();
+
+/**
+* Compare a UTF-8 string to an UTF-16 string.
+*
+* Returns 0 if the strings are equal, -1 if aUTF8String is less
+* than aUTF16Count, and 1 in the reverse case.  In case of fatal
+* error (eg the strings are not valid UTF8 and UTF16 respectively),
+* this method will return INT32_MIN.
+*/
+int32_t CompareUTF8toUTF16(const nsASingleFragmentCString& aUTF8String,
+                           const nsASingleFragmentString& aUTF16String);
+
+void AppendUCS4ToUTF16(const uint32_t aSource, nsAString& aDest);
+
+template<class T>
+inline bool
+EnsureStringLength(T& aStr, uint32_t aLen)
+{
+  aStr.SetLength(aLen);
+  return (aStr.Length() == aLen);
+}
+
+#endif // !defined(nsReadableUtils_h___)
diff --git a/xpcom/string/nsReadableUtilsImpl.h b/xpcom/string/nsReadableUtilsImpl.h
new file mode 100644
index 000000000..ff1497b51
--- /dev/null
+++ b/xpcom/string/nsReadableUtilsImpl.h
@@ -0,0 +1,54 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdint.h>
+
+namespace mozilla {
+
+inline bool IsASCII(char16_t aChar) {
+  return (aChar & 0xFF80) == 0;
+}
+
+/**
+ * Provides a pointer before or equal to |aPtr| that is is suitably aligned.
+ */
+inline const char16_t* aligned(const char16_t* aPtr, const uintptr_t aMask)
+{
+  return reinterpret_cast<const char16_t*>(
+      reinterpret_cast<const uintptr_t>(aPtr) & ~aMask);
+}
+
+/**
+ * Structures for word-sized vectorization of ASCII checking for UTF-16
+ * strings.
+ */
+template<size_t size> struct NonASCIIParameters;
+template<> struct NonASCIIParameters<4> {
+  static inline size_t mask() { return 0xff80ff80; }
+  static inline uintptr_t alignMask() { return 0x3; }
+  static inline size_t numUnicharsPerWord() { return 2; }
+};
+
+template<> struct NonASCIIParameters<8> {
+  static inline size_t mask() {
+    static const uint64_t maskAsUint64 = UINT64_C(0xff80ff80ff80ff80);
+    // We have to explicitly cast this 64-bit value to a size_t, or else
+    // compilers for 32-bit platforms will warn about it being too large to fit
+    // in the size_t return type. (Fortunately, this code isn't actually
+    // invoked on 32-bit platforms -- they'll use the <4> specialization above.
+    // So it is, in fact, OK that this value is too large for a 32-bit size_t.)
+    return (size_t)maskAsUint64;
+  }
+  static inline uintptr_t alignMask() { return 0x7; }
+  static inline size_t numUnicharsPerWord() { return 4; }
+};
+
+namespace SSE2 {
+
+int32_t FirstNonASCII(const char16_t* aBegin, const char16_t* aEnd);
+
+} // namespace SSE2
+} // namespace mozilla
diff --git a/xpcom/string/nsReadableUtilsSSE2.cpp b/xpcom/string/nsReadableUtilsSSE2.cpp
new file mode 100644
index 000000000..fe01d57af
--- /dev/null
+++ b/xpcom/string/nsReadableUtilsSSE2.cpp
@@ -0,0 +1,70 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <emmintrin.h>
+
+#include "nsReadableUtilsImpl.h"
+
+namespace mozilla {
+namespace SSE2 {
+
+static inline bool
+is_zero (__m128i x)
+{
+  return
+    _mm_movemask_epi8(_mm_cmpeq_epi8(x, _mm_setzero_si128())) == 0xffff;
+}
+
+int32_t
+FirstNonASCII(const char16_t* aBegin, const char16_t* aEnd)
+{
+  const size_t kNumUnicharsPerVector = sizeof(__m128i) / sizeof(char16_t);
+  typedef NonASCIIParameters<sizeof(size_t)> p;
+  const size_t kMask = p::mask();
+  const uintptr_t kXmmAlignMask = 0xf;
+  const uint16_t kShortMask = 0xff80;
+  const size_t kNumUnicharsPerWord = p::numUnicharsPerWord();
+
+  const char16_t* idx = aBegin;
+
+  // Align ourselves to a 16-byte boundary as required by _mm_load_si128
+  for (; idx != aEnd && ((uintptr_t(idx) & kXmmAlignMask) != 0); idx++) {
+    if (!IsASCII(*idx)) {
+      return idx - aBegin;
+    }
+  }
+
+  // Check one XMM register (16 bytes) at a time.
+  const char16_t* vectWalkEnd = aligned(aEnd, kXmmAlignMask);
+  __m128i vectmask = _mm_set1_epi16(static_cast<int16_t>(kShortMask));
+  for (; idx != vectWalkEnd; idx += kNumUnicharsPerVector) {
+    const __m128i vect = *reinterpret_cast<const __m128i*>(idx);
+    if (!is_zero(_mm_and_si128(vect, vectmask))) {
+      return idx - aBegin;
+    }
+  }
+
+  // Check one word at a time.
+  const char16_t* wordWalkEnd = aligned(aEnd, p::alignMask());
+  for(; idx != wordWalkEnd; idx += kNumUnicharsPerWord) {
+    const size_t word = *reinterpret_cast<const size_t*>(idx);
+    if (word & kMask) {
+      return idx - aBegin;
+    }
+  }
+
+  // Take care of the remainder one character at a time.
+  for (; idx != aEnd; idx++) {
+    if (!IsASCII(*idx)) {
+      return idx - aBegin;
+    }
+  }
+
+  return -1;
+}
+
+} // namespace SSE2
+} // namespace mozilla
diff --git a/xpcom/string/nsString.cpp b/xpcom/string/nsString.cpp
new file mode 100644
index 000000000..2759eb4ca
--- /dev/null
+++ b/xpcom/string/nsString.cpp
@@ -0,0 +1,17 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsString.h"
+
+// define nsString
+#include "string-template-def-unichar.h"
+#include "nsTString.cpp"
+#include "string-template-undef.h"
+
+// define nsCString
+#include "string-template-def-char.h"
+#include "nsTString.cpp"
+#include "string-template-undef.h"
diff --git a/xpcom/string/nsString.h b/xpcom/string/nsString.h
new file mode 100644
index 000000000..580e4113d
--- /dev/null
+++ b/xpcom/string/nsString.h
@@ -0,0 +1,209 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsString_h___
+#define nsString_h___
+
+#include "mozilla/Attributes.h"
+
+#include "nsSubstring.h"
+#include "nsDependentSubstring.h"
+#include "nsReadableUtils.h"
+
+#include <new>
+
+// enable support for the obsolete string API if not explicitly disabled
+#ifndef MOZ_STRING_WITH_OBSOLETE_API
+#define MOZ_STRING_WITH_OBSOLETE_API 1
+#endif
+
+#if MOZ_STRING_WITH_OBSOLETE_API
+// radix values for ToInteger/AppendInt
+#define kRadix10        (10)
+#define kRadix16        (16)
+#define kAutoDetect     (100)
+#define kRadixUnknown   (kAutoDetect+1)
+#define IGNORE_CASE     (true)
+#endif
+
+
+// declare nsString, et. al.
+#include "string-template-def-unichar.h"
+#include "nsTString.h"
+#include "string-template-undef.h"
+
+// declare nsCString, et. al.
+#include "string-template-def-char.h"
+#include "nsTString.h"
+#include "string-template-undef.h"
+
+static_assert(sizeof(char16_t) == 2, "size of char16_t must be 2");
+static_assert(sizeof(nsString::char_type) == 2,
+              "size of nsString::char_type must be 2");
+static_assert(nsString::char_type(-1) > nsString::char_type(0),
+              "nsString::char_type must be unsigned");
+static_assert(sizeof(nsCString::char_type) == 1,
+              "size of nsCString::char_type must be 1");
+
+
+/**
+ * A helper class that converts a UTF-16 string to ASCII in a lossy manner
+ */
+class NS_LossyConvertUTF16toASCII : public nsAutoCString
+{
+public:
+  explicit NS_LossyConvertUTF16toASCII(const char16ptr_t aString)
+  {
+    LossyAppendUTF16toASCII(aString, *this);
+  }
+
+  NS_LossyConvertUTF16toASCII(const char16ptr_t aString, uint32_t aLength)
+  {
+    LossyAppendUTF16toASCII(Substring(aString, aLength), *this);
+  }
+
+  explicit NS_LossyConvertUTF16toASCII(const nsAString& aString)
+  {
+    LossyAppendUTF16toASCII(aString, *this);
+  }
+
+private:
+  // NOT TO BE IMPLEMENTED
+  NS_LossyConvertUTF16toASCII(char) = delete;
+};
+
+
+class NS_ConvertASCIItoUTF16 : public nsAutoString
+{
+public:
+  explicit NS_ConvertASCIItoUTF16(const char* aCString)
+  {
+    AppendASCIItoUTF16(aCString, *this);
+  }
+
+  NS_ConvertASCIItoUTF16(const char* aCString, uint32_t aLength)
+  {
+    AppendASCIItoUTF16(Substring(aCString, aLength), *this);
+  }
+
+  explicit NS_ConvertASCIItoUTF16(const nsACString& aCString)
+  {
+    AppendASCIItoUTF16(aCString, *this);
+  }
+
+private:
+  // NOT TO BE IMPLEMENTED
+  NS_ConvertASCIItoUTF16(char16_t) = delete;
+};
+
+
+/**
+ * A helper class that converts a UTF-16 string to UTF-8
+ */
+class NS_ConvertUTF16toUTF8 : public nsAutoCString
+{
+public:
+  explicit NS_ConvertUTF16toUTF8(const char16ptr_t aString)
+  {
+    AppendUTF16toUTF8(aString, *this);
+  }
+
+  NS_ConvertUTF16toUTF8(const char16ptr_t aString, uint32_t aLength)
+  {
+    AppendUTF16toUTF8(Substring(aString, aLength), *this);
+  }
+
+  explicit NS_ConvertUTF16toUTF8(const nsAString& aString)
+  {
+    AppendUTF16toUTF8(aString, *this);
+  }
+
+private:
+  // NOT TO BE IMPLEMENTED
+  NS_ConvertUTF16toUTF8(char) = delete;
+};
+
+
+class NS_ConvertUTF8toUTF16 : public nsAutoString
+{
+public:
+  explicit NS_ConvertUTF8toUTF16(const char* aCString)
+  {
+    AppendUTF8toUTF16(aCString, *this);
+  }
+
+  NS_ConvertUTF8toUTF16(const char* aCString, uint32_t aLength)
+  {
+    AppendUTF8toUTF16(Substring(aCString, aLength), *this);
+  }
+
+  explicit NS_ConvertUTF8toUTF16(const nsACString& aCString)
+  {
+    AppendUTF8toUTF16(aCString, *this);
+  }
+
+private:
+  // NOT TO BE IMPLEMENTED
+  NS_ConvertUTF8toUTF16(char16_t) = delete;
+};
+
+
+#ifdef MOZ_USE_CHAR16_WRAPPER
+
+inline char16_t*
+wwc(wchar_t* aStr)
+{
+  return reinterpret_cast<char16_t*>(aStr);
+}
+
+inline wchar_t*
+wwc(char16_t* aStr)
+{
+  return reinterpret_cast<wchar_t*>(aStr);
+}
+
+inline const char16_t*
+wwc(const wchar_t* aStr)
+{
+  return reinterpret_cast<const char16_t*>(aStr);
+}
+
+inline const wchar_t*
+wwc(const char16_t* aStr)
+{
+  return reinterpret_cast<const wchar_t*>(aStr);
+}
+
+#else
+
+inline char16_t*
+wwc(char16_t* aStr)
+{
+  return aStr;
+}
+
+inline const char16_t*
+wwc(const char16_t* aStr)
+{
+  return aStr;
+}
+
+#endif
+
+// the following are included/declared for backwards compatibility
+typedef nsAutoString nsVoidableString;
+
+#include "nsDependentString.h"
+#include "nsLiteralString.h"
+#include "nsPromiseFlatString.h"
+
+// need to include these for backwards compatibility
+#include "nsMemory.h"
+#include <string.h>
+#include <stdio.h>
+#include "plhash.h"
+
+#endif // !defined(nsString_h___)
diff --git a/xpcom/string/nsStringBuffer.h b/xpcom/string/nsStringBuffer.h
new file mode 100644
index 000000000..432289bf6
--- /dev/null
+++ b/xpcom/string/nsStringBuffer.h
@@ -0,0 +1,160 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsStringBuffer_h__
+#define nsStringBuffer_h__
+
+#include "mozilla/Atomics.h"
+#include "mozilla/MemoryReporting.h"
+
+template<class T> struct already_AddRefed;
+
+/**
+ * This structure precedes the string buffers "we" allocate.  It may be the
+ * case that nsTAString::mData does not point to one of these special
+ * buffers.  The mFlags member variable distinguishes the buffer type.
+ *
+ * When this header is in use, it enables reference counting, and capacity
+ * tracking.  NOTE: A string buffer can be modified only if its reference
+ * count is 1.
+ */
+class nsStringBuffer
+{
+private:
+  friend class CheckStaticAtomSizes;
+
+  mozilla::Atomic<int32_t> mRefCount;
+  uint32_t mStorageSize;
+
+public:
+
+  /**
+   * Allocates a new string buffer, with given size in bytes and a
+   * reference count of one.  When the string buffer is no longer needed,
+   * it should be released via Release.
+   *
+   * It is up to the caller to set the bytes corresponding to the string
+   * buffer by calling the Data method to fetch the raw data pointer.  Care
+   * must be taken to properly null terminate the character array.  The
+   * storage size can be greater than the length of the actual string
+   * (i.e., it is not required that the null terminator appear in the last
+   * storage unit of the string buffer's data).
+   *
+   * @return new string buffer or null if out of memory.
+   */
+  static already_AddRefed<nsStringBuffer> Alloc(size_t aStorageSize);
+
+  /**
+   * Resizes the given string buffer to the specified storage size.  This
+   * method must not be called on a readonly string buffer.  Use this API
+   * carefully!!
+   *
+   * This method behaves like the ANSI-C realloc function.  (i.e., If the
+   * allocation fails, null will be returned and the given string buffer
+   * will remain unmodified.)
+   *
+   * @see IsReadonly
+   */
+  static nsStringBuffer* Realloc(nsStringBuffer* aBuf, size_t aStorageSize);
+
+  /**
+   * Increment the reference count on this string buffer.
+   */
+  void NS_FASTCALL AddRef();
+
+  /**
+   * Decrement the reference count on this string buffer.  The string
+   * buffer will be destroyed when its reference count reaches zero.
+   */
+  void NS_FASTCALL Release();
+
+  /**
+   * This method returns the string buffer corresponding to the given data
+   * pointer.  The data pointer must have been returned previously by a
+   * call to the nsStringBuffer::Data method.
+   */
+  static nsStringBuffer* FromData(void* aData)
+  {
+    return reinterpret_cast<nsStringBuffer*>(aData) - 1;
+  }
+
+  /**
+   * This method returns the data pointer for this string buffer.
+   */
+  void* Data() const
+  {
+    return const_cast<char*>(reinterpret_cast<const char*>(this + 1));
+  }
+
+  /**
+   * This function returns the storage size of a string buffer in bytes.
+   * This value is the same value that was originally passed to Alloc (or
+   * Realloc).
+   */
+  uint32_t StorageSize() const
+  {
+    return mStorageSize;
+  }
+
+  /**
+   * If this method returns false, then the caller can be sure that their
+   * reference to the string buffer is the only reference to the string
+   * buffer, and therefore it has exclusive access to the string buffer and
+   * associated data.  However, if this function returns true, then other
+   * consumers may rely on the data in this buffer being immutable and
+   * other threads may access this buffer simultaneously.
+   */
+  bool IsReadonly() const
+  {
+    return mRefCount > 1;
+  }
+
+  /**
+   * The FromString methods return a string buffer for the given string
+   * object or null if the string object does not have a string buffer.
+   * The reference count of the string buffer is NOT incremented by these
+   * methods.  If the caller wishes to hold onto the returned value, then
+   * the returned string buffer must have its reference count incremented
+   * via a call to the AddRef method.
+   */
+  static nsStringBuffer* FromString(const nsAString& aStr);
+  static nsStringBuffer* FromString(const nsACString& aStr);
+
+  /**
+   * The ToString methods assign this string buffer to a given string
+   * object.  If the string object does not support sharable string
+   * buffers, then its value will be set to a copy of the given string
+   * buffer.  Otherwise, these methods increment the reference count of the
+   * given string buffer.  It is important to specify the length (in
+   * storage units) of the string contained in the string buffer since the
+   * length of the string may be less than its storage size.  The string
+   * must have a null terminator at the offset specified by |len|.
+   *
+   * NOTE: storage size is measured in bytes even for wide strings;
+   *       however, string length is always measured in storage units
+   *       (2-byte units for wide strings).
+   */
+  void ToString(uint32_t aLen, nsAString& aStr, bool aMoveOwnership = false);
+  void ToString(uint32_t aLen, nsACString& aStr, bool aMoveOwnership = false);
+
+  /**
+   * This measures the size only if the StringBuffer is unshared.
+   */
+  size_t SizeOfIncludingThisIfUnshared(mozilla::MallocSizeOf aMallocSizeOf) const;
+
+  /**
+   * This measures the size regardless of whether the StringBuffer is
+   * unshared.
+   *
+   * WARNING: Only use this if you really know what you are doing, because
+   * it can easily lead to double-counting strings.  If you do use them,
+   * please explain clearly in a comment why it's safe and won't lead to
+   * double-counting.
+   */
+  size_t SizeOfIncludingThisEvenIfShared(mozilla::MallocSizeOf aMallocSizeOf) const;
+};
+
+#endif /* !defined(nsStringBuffer_h__ */
diff --git a/xpcom/string/nsStringComparator.cpp b/xpcom/string/nsStringComparator.cpp
new file mode 100644
index 000000000..81f1629f8
--- /dev/null
+++ b/xpcom/string/nsStringComparator.cpp
@@ -0,0 +1,39 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <ctype.h>
+#include "nsAString.h"
+#include "plstr.h"
+
+
+// define nsStringComparator
+#include "string-template-def-unichar.h"
+#include "nsTStringComparator.cpp"
+#include "string-template-undef.h"
+
+// define nsCStringComparator
+#include "string-template-def-char.h"
+#include "nsTStringComparator.cpp"
+#include "string-template-undef.h"
+
+
+int
+nsCaseInsensitiveCStringComparator::operator()(const char_type* aLhs,
+                                               const char_type* aRhs,
+                                               uint32_t aLhsLength,
+                                               uint32_t aRhsLength) const
+{
+  if (aLhsLength != aRhsLength) {
+    return (aLhsLength > aRhsLength) ? 1 : -1;
+  }
+  int32_t result = int32_t(PL_strncasecmp(aLhs, aRhs, aLhsLength));
+  //Egads. PL_strncasecmp is returning *very* negative numbers.
+  //Some folks expect -1,0,1, so let's temper its enthusiasm.
+  if (result < 0) {
+    result = -1;
+  }
+  return result;
+}
diff --git a/xpcom/string/nsStringFwd.h b/xpcom/string/nsStringFwd.h
new file mode 100644
index 000000000..a9162f384
--- /dev/null
+++ b/xpcom/string/nsStringFwd.h
@@ -0,0 +1,64 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* nsStringFwd.h --- forward declarations for string classes */
+
+#ifndef nsStringFwd_h___
+#define nsStringFwd_h___
+
+#include "nscore.h"
+
+#ifndef MOZILLA_INTERNAL_API
+#error Internal string headers are not available from external-linkage code.
+#endif
+
+/**
+ * double-byte (char16_t) string types
+ */
+
+class nsAString;
+class nsSubstringTuple;
+class nsString;
+class nsAutoString;
+class nsDependentString;
+class nsDependentSubstring;
+class nsPromiseFlatString;
+class nsStringComparator;
+class nsDefaultStringComparator;
+class nsXPIDLString;
+
+
+/**
+ * single-byte (char) string types
+ */
+
+class nsACString;
+class nsCSubstringTuple;
+class nsCString;
+class nsAutoCString;
+class nsDependentCString;
+class nsDependentCSubstring;
+class nsPromiseFlatCString;
+class nsCStringComparator;
+class nsDefaultCStringComparator;
+class nsXPIDLCString;
+
+
+/**
+ * typedefs for backwards compatibility
+ */
+
+typedef nsAString             nsSubstring;
+typedef nsACString            nsCSubstring;
+
+typedef nsString              nsAFlatString;
+typedef nsSubstring           nsASingleFragmentString;
+
+typedef nsCString             nsAFlatCString;
+typedef nsCSubstring          nsASingleFragmentCString;
+
+
+#endif /* !defined(nsStringFwd_h___) */
diff --git a/xpcom/string/nsStringIterator.h b/xpcom/string/nsStringIterator.h
new file mode 100644
index 000000000..e309a21e9
--- /dev/null
+++ b/xpcom/string/nsStringIterator.h
@@ -0,0 +1,268 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsStringIterator_h___
+#define nsStringIterator_h___
+
+#include "nsCharTraits.h"
+#include "nsAlgorithm.h"
+#include "nsDebug.h"
+
+/**
+ * @see nsTAString
+ */
+
+template <class CharT>
+class nsReadingIterator
+{
+public:
+  typedef nsReadingIterator<CharT>    self_type;
+  typedef ptrdiff_t                   difference_type;
+  typedef size_t                      size_type;
+  typedef CharT                       value_type;
+  typedef const CharT*                pointer;
+  typedef const CharT&                reference;
+
+private:
+  friend class nsAString;
+  friend class nsACString;
+
+  // unfortunately, the API for nsReadingIterator requires that the
+  // iterator know its start and end positions.  this was needed when
+  // we supported multi-fragment strings, but now it is really just
+  // extra baggage.  we should remove mStart and mEnd at some point.
+
+  const CharT* mStart;
+  const CharT* mEnd;
+  const CharT* mPosition;
+
+public:
+  nsReadingIterator()
+  {
+  }
+  // nsReadingIterator( const nsReadingIterator<CharT>& );                    // auto-generated copy-constructor OK
+  // nsReadingIterator<CharT>& operator=( const nsReadingIterator<CharT>& );  // auto-generated copy-assignment operator OK
+
+  pointer get() const
+  {
+    return mPosition;
+  }
+
+  CharT operator*() const
+  {
+    return *get();
+  }
+
+  self_type& operator++()
+  {
+    ++mPosition;
+    return *this;
+  }
+
+  self_type operator++(int)
+  {
+    self_type result(*this);
+    ++mPosition;
+    return result;
+  }
+
+  self_type& operator--()
+  {
+    --mPosition;
+    return *this;
+  }
+
+  self_type operator--(int)
+  {
+    self_type result(*this);
+    --mPosition;
+    return result;
+  }
+
+  self_type& advance(difference_type aN)
+  {
+    if (aN > 0) {
+      difference_type step = XPCOM_MIN(aN, mEnd - mPosition);
+
+      NS_ASSERTION(step > 0,
+                   "can't advance a reading iterator beyond the end of a string");
+
+      mPosition += step;
+    } else if (aN < 0) {
+      difference_type step = XPCOM_MAX(aN, -(mPosition - mStart));
+
+      NS_ASSERTION(step < 0,
+                   "can't advance (backward) a reading iterator beyond the end of a string");
+
+      mPosition += step;
+    }
+    return *this;
+  }
+
+  // We return an unsigned type here (with corresponding assert) rather than
+  // the more usual difference_type because we want to make this class go
+  // away in favor of mozilla::RangedPtr.  Since RangedPtr has the same
+  // requirement we are enforcing here, the transition ought to be much
+  // smoother.
+  size_type operator-(const self_type& aOther) const
+  {
+    MOZ_ASSERT(mPosition >= aOther.mPosition);
+    return mPosition - aOther.mPosition;
+  }
+};
+
+/**
+ * @see nsTAString
+ */
+
+template <class CharT>
+class nsWritingIterator
+{
+public:
+  typedef nsWritingIterator<CharT>   self_type;
+  typedef ptrdiff_t                  difference_type;
+  typedef size_t                     size_type;
+  typedef CharT                      value_type;
+  typedef CharT*                     pointer;
+  typedef CharT&                     reference;
+
+private:
+  friend class nsAString;
+  friend class nsACString;
+
+  // unfortunately, the API for nsWritingIterator requires that the
+  // iterator know its start and end positions.  this was needed when
+  // we supported multi-fragment strings, but now it is really just
+  // extra baggage.  we should remove mStart and mEnd at some point.
+
+  CharT* mStart;
+  CharT* mEnd;
+  CharT* mPosition;
+
+public:
+  nsWritingIterator()
+  {
+  }
+  // nsWritingIterator( const nsWritingIterator<CharT>& );                    // auto-generated copy-constructor OK
+  // nsWritingIterator<CharT>& operator=( const nsWritingIterator<CharT>& );  // auto-generated copy-assignment operator OK
+
+  pointer get() const
+  {
+    return mPosition;
+  }
+
+  reference operator*() const
+  {
+    return *get();
+  }
+
+  self_type& operator++()
+  {
+    ++mPosition;
+    return *this;
+  }
+
+  self_type operator++(int)
+  {
+    self_type result(*this);
+    ++mPosition;
+    return result;
+  }
+
+  self_type& operator--()
+  {
+    --mPosition;
+    return *this;
+  }
+
+  self_type operator--(int)
+  {
+    self_type result(*this);
+    --mPosition;
+    return result;
+  }
+
+  self_type& advance(difference_type aN)
+  {
+    if (aN > 0) {
+      difference_type step = XPCOM_MIN(aN, mEnd - mPosition);
+
+      NS_ASSERTION(step > 0,
+                   "can't advance a writing iterator beyond the end of a string");
+
+      mPosition += step;
+    } else if (aN < 0) {
+      difference_type step = XPCOM_MAX(aN, -(mPosition - mStart));
+
+      NS_ASSERTION(step < 0,
+                   "can't advance (backward) a writing iterator beyond the end of a string");
+
+      mPosition += step;
+    }
+    return *this;
+  }
+
+  // We return an unsigned type here (with corresponding assert) rather than
+  // the more usual difference_type because we want to make this class go
+  // away in favor of mozilla::RangedPtr.  Since RangedPtr has the same
+  // requirement we are enforcing here, the transition ought to be much
+  // smoother.
+  size_type operator-(const self_type& aOther) const
+  {
+    MOZ_ASSERT(mPosition >= aOther.mPosition);
+    return mPosition - aOther.mPosition;
+  }
+};
+
+template <class CharT>
+struct nsCharSinkTraits<nsWritingIterator<CharT>>
+{
+  static void
+  write(nsWritingIterator<CharT>& aIter, const CharT* aStr, uint32_t aN)
+  {
+    nsCharTraits<CharT>::move(aIter.get(), aStr, aN);
+    aIter.advance(aN);
+  }
+};
+
+template <class CharT>
+inline bool
+operator==(const nsReadingIterator<CharT>& aLhs,
+           const nsReadingIterator<CharT>& aRhs)
+{
+  return aLhs.get() == aRhs.get();
+}
+
+template <class CharT>
+inline bool
+operator!=(const nsReadingIterator<CharT>& aLhs,
+           const nsReadingIterator<CharT>& aRhs)
+{
+  return aLhs.get() != aRhs.get();
+}
+
+
+//
+// |nsWritingIterator|s
+//
+
+template <class CharT>
+inline bool
+operator==(const nsWritingIterator<CharT>& aLhs,
+           const nsWritingIterator<CharT>& aRhs)
+{
+  return aLhs.get() == aRhs.get();
+}
+
+template <class CharT>
+inline bool
+operator!=(const nsWritingIterator<CharT>& aLhs,
+           const nsWritingIterator<CharT>& aRhs)
+{
+  return aLhs.get() != aRhs.get();
+}
+
+#endif /* !defined(nsStringIterator_h___) */
diff --git a/xpcom/string/nsStringObsolete.cpp b/xpcom/string/nsStringObsolete.cpp
new file mode 100644
index 000000000..bd6daacab
--- /dev/null
+++ b/xpcom/string/nsStringObsolete.cpp
@@ -0,0 +1,1053 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsString.h"
+
+
+/**
+ * nsTString obsolete API support
+ */
+
+#if MOZ_STRING_WITH_OBSOLETE_API
+
+#include "nsDependentString.h"
+#include "nsDependentSubstring.h"
+#include "nsReadableUtils.h"
+#include "nsCRT.h"
+#include "nsUTF8Utils.h"
+#include "prdtoa.h"
+
+/* ***** BEGIN RICKG BLOCK *****
+ *
+ * NOTE: This section of code was extracted from rickg's bufferRoutines.h file.
+ *       For the most part it remains unmodified.  We want to eliminate (or at
+ *       least clean up) this code at some point.  If you find the formatting
+ *       in this section somewhat inconsistent, don't blame me! ;-)
+ */
+
+// avoid STDC's tolower since it may do weird things with non-ASCII bytes
+inline char
+ascii_tolower(char aChar)
+{
+  if (aChar >= 'A' && aChar <= 'Z')
+    return aChar + ('a' - 'A');
+  return aChar;
+}
+
+//-----------------------------------------------------------------------------
+//
+//  This set of methods is used to search a buffer looking for a char.
+//
+
+
+/**
+ *  This methods cans the given buffer for the given char
+ *
+ *  @update  gess 02/17/00
+ *  @param   aDest is the buffer to be searched
+ *  @param   aDestLength is the size (in char-units, not bytes) of the buffer
+ *  @param   anOffset is the start pos to begin searching
+ *  @param   aChar is the target character we're looking for
+ *  @param   aCount tells us how many characters to iterate through (which may be different than aLength); -1 means use full length.
+ *  @return  index of pos if found, else -1 (kNotFound)
+ */
+static int32_t
+FindChar1(const char* aDest,uint32_t aDestLength,int32_t anOffset,const char16_t aChar,int32_t aCount) {
+
+  if(anOffset < 0)
+    anOffset=0;
+
+  if(aCount < 0)
+    aCount = (int32_t)aDestLength;
+
+  if((aChar < 256) && (0 < aDestLength) && ((uint32_t)anOffset < aDestLength)) {
+
+    //We'll only search if the given aChar is within the normal ascii a range,
+    //(Since this string is definitely within the ascii range).
+
+    if(0<aCount) {
+
+      const char* left= aDest+anOffset;
+      const char* last= left+aCount;
+      const char* max = aDest+aDestLength;
+      const char* end = (last<max) ? last : max;
+
+      int32_t theMax = end-left;
+      if(0<theMax) {
+
+        unsigned char theChar = (unsigned char) aChar;
+        const char* result=(const char*)memchr(left, (int)theChar, theMax);
+
+        if(result)
+          return result-aDest;
+
+      }
+    }
+  }
+
+  return kNotFound;
+}
+
+
+/**
+ *  This methods cans the given buffer for the given char
+ *
+ *  @update  gess 3/25/98
+ *  @param   aDest is the buffer to be searched
+ *  @param   aDestLength is the size (in char-units, not bytes) of the buffer
+ *  @param   anOffset is the start pos to begin searching
+ *  @param   aChar is the target character we're looking for
+ *  @param   aCount tells us how many characters to iterate through (which may be different than aLength); -1 means use full length.
+ *  @return  index of pos if found, else -1 (kNotFound)
+ */
+static int32_t
+FindChar2(const char16_t* aDest,uint32_t aDestLength,int32_t anOffset,const char16_t aChar,int32_t aCount) {
+
+  if(anOffset < 0)
+    anOffset=0;
+
+  if(aCount < 0)
+    aCount = (int32_t)aDestLength;
+
+  if((0<aDestLength) && ((uint32_t)anOffset < aDestLength)) {
+
+    if(0<aCount) {
+
+      const char16_t* root = aDest;
+      const char16_t* left = root+anOffset;
+      const char16_t* last = left+aCount;
+      const char16_t* max  = root+aDestLength;
+      const char16_t* end  = (last<max) ? last : max;
+
+      while(left<end){
+
+        if(*left==aChar)
+          return (left-root);
+
+        ++left;
+      }
+    }
+  }
+
+  return kNotFound;
+}
+
+
+/**
+ *  This methods cans the given buffer (in reverse) for the given char
+ *
+ *  @update  gess 02/17/00
+ *  @param   aDest is the buffer to be searched
+ *  @param   aDestLength is the size (in char-units, not bytes) of the buffer
+ *  @param   anOffset is the start pos to begin searching
+ *  @param   aChar is the target character we're looking for
+ *  @param   aCount tells us how many characters to iterate through (which may be different than aLength); -1 means use full length.
+ *  @return  index of pos if found, else -1 (kNotFound)
+ */
+
+static int32_t
+RFindChar1(const char* aDest,uint32_t aDestLength,int32_t anOffset,const char16_t aChar,int32_t aCount) {
+
+  if(anOffset < 0)
+    anOffset=(int32_t)aDestLength-1;
+
+  if(aCount < 0)
+    aCount = int32_t(aDestLength);
+
+  if((aChar<256) && (0 < aDestLength) && ((uint32_t)anOffset < aDestLength)) {
+
+    //We'll only search if the given aChar is within the normal ascii a range,
+    //(Since this string is definitely within the ascii range).
+
+    if(0 < aCount) {
+
+      const char* rightmost = aDest + anOffset;
+      const char* min       = rightmost - aCount + 1;
+      const char* leftmost  = (min<aDest) ? aDest: min;
+
+      char theChar=(char)aChar;
+      while(leftmost <= rightmost){
+
+        if((*rightmost) == theChar)
+          return rightmost - aDest;
+
+        --rightmost;
+      }
+    }
+  }
+
+  return kNotFound;
+}
+
+
+/**
+ *  This methods cans the given buffer for the given char
+ *
+ *  @update  gess 3/25/98
+ *  @param   aDest is the buffer to be searched
+ *  @param   aDestLength is the size (in char-units, not bytes) of the buffer
+ *  @param   anOffset is the start pos to begin searching
+ *  @param   aChar is the target character we're looking for
+ *  @param   aCount tells us how many characters to iterate through (which may be different than aLength); -1 means use full length.
+ *  @return  index of pos if found, else -1 (kNotFound)
+ */
+static int32_t
+RFindChar2(const char16_t* aDest,uint32_t aDestLength,int32_t anOffset,const char16_t aChar,int32_t aCount) {
+
+  if(anOffset < 0)
+    anOffset=(int32_t)aDestLength-1;
+
+  if(aCount < 0)
+    aCount = int32_t(aDestLength);
+
+  if((0 < aDestLength) && ((uint32_t)anOffset < aDestLength)) {
+
+    if(0 < aCount) {
+
+      const char16_t* root      = aDest;
+      const char16_t* rightmost = root + anOffset;
+      const char16_t* min       = rightmost - aCount + 1;
+      const char16_t* leftmost  = (min<root) ? root: min;
+
+      while(leftmost <= rightmost){
+
+        if((*rightmost) == aChar)
+          return rightmost - root;
+
+        --rightmost;
+      }
+    }
+  }
+
+  return kNotFound;
+}
+
+//-----------------------------------------------------------------------------
+//
+//  This set of methods is used to compare one buffer onto another.  The
+//  functions are differentiated by the size of source and dest character
+//  sizes.  WARNING: Your destination buffer MUST be big enough to hold all the
+//  source bytes.  We don't validate these ranges here (this should be done in
+//  higher level routines).
+//
+
+
+/**
+ * This method compares the data in one buffer with another
+ * @update	gess 01/04/99
+ * @param   aStr1 is the first buffer to be compared
+ * @param   aStr2 is the 2nd buffer to be compared
+ * @param   aCount is the number of chars to compare
+ * @param   aIgnoreCase tells us whether to use a case-sensitive comparison
+ * @return  -1,0,1 depending on <,==,>
+ */
+static
+#ifdef __SUNPRO_CC
+inline
+#endif /* __SUNPRO_CC */
+int32_t
+Compare1To1(const char* aStr1,const char* aStr2,uint32_t aCount,bool aIgnoreCase) {
+  int32_t result=0;
+  if(aIgnoreCase)
+    result=int32_t(PL_strncasecmp(aStr1, aStr2, aCount));
+  else
+    result=nsCharTraits<char>::compare(aStr1,aStr2,aCount);
+
+  // alien comparisons may return out-of-bound answers
+  //  instead of the -1, 0, 1 expected by most clients
+  if ( result < -1 )
+    result = -1;
+  else if ( result > 1 )
+    result = 1;
+  return result;
+}
+
+/**
+ * This method compares the data in one buffer with another
+ * @update	gess 01/04/99
+ * @param   aStr1 is the first buffer to be compared
+ * @param   aStr2 is the 2nd buffer to be compared
+ * @param   aCount is the number of chars to compare
+ * @param   aIgnoreCase tells us whether to use a case-sensitive comparison
+ * @return  -1,0,1 depending on <,==,>
+ */
+static
+#ifdef __SUNPRO_CC
+inline
+#endif /* __SUNPRO_CC */
+int32_t
+Compare2To2(const char16_t* aStr1,const char16_t* aStr2,uint32_t aCount){
+  int32_t result;
+
+  if ( aStr1 && aStr2 )
+    result = nsCharTraits<char16_t>::compare(aStr1, aStr2, aCount);
+
+  // The following cases are rare and survivable caller errors.
+  //  Two null pointers are equal, but any string, even 0 length
+  //  is greater than a null pointer.  It might not really matter,
+  //  but we pick something reasonable anyway.
+  else if ( !aStr1 && !aStr2 )
+    result = 0;
+  else if ( aStr1 )
+    result = 1;
+  else
+    result = -1;
+
+  // alien comparisons may give answers outside the -1, 0, 1 expected by callers
+  if ( result < -1 )
+    result = -1;
+  else if ( result > 1 )
+    result = 1;
+  return result;
+}
+
+
+/**
+ * This method compares the data in one buffer with another
+ * @update	gess 01/04/99
+ * @param   aStr1 is the first buffer to be compared
+ * @param   aStr2 is the 2nd buffer to be compared
+ * @param   aCount is the number of chars to compare
+ * @param   aIgnoreCase tells us whether to use a case-sensitive comparison
+ * @return  -1,0,1 depending on <,==,>
+ */
+static
+#ifdef __SUNPRO_CC
+inline
+#endif /* __SUNPRO_CC */
+int32_t
+Compare2To1(const char16_t* aStr1,const char* aStr2,uint32_t aCount,bool aIgnoreCase){
+  const char16_t* s1 = aStr1;
+  const char *s2 = aStr2;
+
+  if (aStr1 && aStr2) {
+    if (aCount != 0) {
+      do {
+
+        char16_t c1 = *s1++;
+        char16_t c2 = char16_t((unsigned char)*s2++);
+
+        if (c1 != c2) {
+#ifdef DEBUG
+          // we won't warn on c1>=128 (the 2-byte value) because often
+          // it is just fine to compare an constant, ascii value (i.e. "body")
+          // against some non-ascii value (i.e. a unicode string that
+          // was downloaded from a web page)
+          if (aIgnoreCase && c2>=128)
+            NS_WARNING("got a non-ASCII string, but we can't do an accurate case conversion!");
+#endif
+
+          // can't do case conversion on characters out of our range
+          if (aIgnoreCase && c1<128 && c2<128) {
+
+            c1 = ascii_tolower(char(c1));
+            c2 = ascii_tolower(char(c2));
+
+            if (c1 == c2) continue;
+          }
+
+          if (c1 < c2) return -1;
+          return 1;
+        }
+      } while (--aCount);
+    }
+  }
+  return 0;
+}
+
+
+/**
+ * This method compares the data in one buffer with another
+ * @update	gess 01/04/99
+ * @param   aStr1 is the first buffer to be compared
+ * @param   aStr2 is the 2nd buffer to be compared
+ * @param   aCount is the number of chars to compare
+ * @param   aIgnoreCase tells us whether to use a case-sensitive comparison
+ * @return  -1,0,1 depending on <,==,>
+ */
+inline int32_t
+Compare1To2(const char* aStr1,const char16_t* aStr2,uint32_t aCount,bool aIgnoreCase){
+  return Compare2To1(aStr2, aStr1, aCount, aIgnoreCase) * -1;
+}
+
+
+//-----------------------------------------------------------------------------
+//
+//  This set of methods is used compress char sequences in a buffer...
+//
+
+
+/**
+ * This method compresses duplicate runs of a given char from the given buffer
+ *
+ * @update	rickg 03.23.2000
+ * @param   aString is the buffer to be manipulated
+ * @param   aLength is the length of the buffer
+ * @param   aSet tells us which chars to compress from given buffer
+ * @param   aEliminateLeading tells us whether to strip chars from the start of the buffer
+ * @param   aEliminateTrailing tells us whether to strip chars from the start of the buffer
+ * @return  the new length of the given buffer
+ */
+static int32_t
+CompressChars1(char* aString,uint32_t aLength,const char* aSet){ 
+
+  char*  from = aString;
+  char*  end =  aString + aLength;
+  char*  to = from;
+
+  //this code converts /n, /t, /r into normal space ' ';
+  //it also compresses runs of whitespace down to a single char...
+  if(aSet && aString && (0 < aLength)){
+    uint32_t aSetLen=strlen(aSet);
+
+    while (from < end) {
+      char theChar = *from++;
+
+      *to++=theChar; //always copy this char...
+
+      if((kNotFound!=FindChar1(aSet,aSetLen,0,theChar,aSetLen))){
+        while (from < end) {
+          theChar = *from++;
+          if(kNotFound==FindChar1(aSet,aSetLen,0,theChar,aSetLen)){
+            *to++ = theChar;
+            break;
+          }
+        } //while
+      } //if
+    } //if
+    *to = 0;
+  }
+  return to - aString;
+}
+
+
+
+/**
+ * This method compresses duplicate runs of a given char from the given buffer
+ *
+ * @update	rickg 03.23.2000
+ * @param   aString is the buffer to be manipulated
+ * @param   aLength is the length of the buffer
+ * @param   aSet tells us which chars to compress from given buffer
+ * @param   aEliminateLeading tells us whether to strip chars from the start of the buffer
+ * @param   aEliminateTrailing tells us whether to strip chars from the start of the buffer
+ * @return  the new length of the given buffer
+ */
+static int32_t
+CompressChars2(char16_t* aString,uint32_t aLength,const char* aSet) {
+
+  char16_t*  from = aString;
+  char16_t*  end =  from + aLength;
+  char16_t*  to = from;
+
+  //this code converts /n, /t, /r into normal space ' ';
+  //it also compresses runs of whitespace down to a single char...
+  if(aSet && aString && (0 < aLength)){
+    uint32_t aSetLen=strlen(aSet);
+
+    while (from < end) {
+      char16_t theChar = *from++;
+
+      *to++=theChar; //always copy this char...
+
+      if((theChar<256) && (kNotFound!=FindChar1(aSet,aSetLen,0,theChar,aSetLen))){
+        while (from < end) {
+          theChar = *from++;
+          if(kNotFound==FindChar1(aSet,aSetLen,0,theChar,aSetLen)){
+            *to++ = theChar;
+            break;
+          }
+        } //while
+      } //if
+    } //if
+    *to = 0;
+  }
+  return to - (char16_t*)aString;
+}
+
+/**
+ * This method strips chars in a given set from the given buffer
+ *
+ * @update	gess 01/04/99
+ * @param   aString is the buffer to be manipulated
+ * @param   aLength is the length of the buffer
+ * @param   aSet tells us which chars to compress from given buffer
+ * @param   aEliminateLeading tells us whether to strip chars from the start of the buffer
+ * @param   aEliminateTrailing tells us whether to strip chars from the start of the buffer
+ * @return  the new length of the given buffer
+ */
+static int32_t
+StripChars1(char* aString,uint32_t aLength,const char* aSet) {
+
+  // XXX(darin): this code should defer writing until necessary.
+
+  char*  to   = aString;
+  char*  from = aString-1;
+  char*  end  = aString + aLength;
+
+  if(aSet && aString && (0 < aLength)){
+    uint32_t aSetLen=strlen(aSet);
+    while (++from < end) {
+      char theChar = *from;
+      if(kNotFound==FindChar1(aSet,aSetLen,0,theChar,aSetLen)){
+        *to++ = theChar;
+      }
+    }
+    *to = 0;
+  }
+  return to - (char*)aString;
+}
+
+
+/**
+ * This method strips chars in a given set from the given buffer
+ *
+ * @update	gess 01/04/99
+ * @param   aString is the buffer to be manipulated
+ * @param   aLength is the length of the buffer
+ * @param   aSet tells us which chars to compress from given buffer
+ * @param   aEliminateLeading tells us whether to strip chars from the start of the buffer
+ * @param   aEliminateTrailing tells us whether to strip chars from the start of the buffer
+ * @return  the new length of the given buffer
+ */
+static int32_t
+StripChars2(char16_t* aString,uint32_t aLength,const char* aSet) {
+
+  // XXX(darin): this code should defer writing until necessary.
+
+  char16_t*  to   = aString;
+  char16_t*  from = aString-1;
+  char16_t*  end  = to + aLength;
+
+  if(aSet && aString && (0 < aLength)){
+    uint32_t aSetLen=strlen(aSet);
+    while (++from < end) {
+      char16_t theChar = *from;
+      //Note the test for ascii range below. If you have a real unicode char,
+      //and you're searching for chars in the (given) ascii string, there's no
+      //point in doing the real search since it's out of the ascii range.
+      if((255<theChar) || (kNotFound==FindChar1(aSet,aSetLen,0,theChar,aSetLen))){
+        *to++ = theChar;
+      }
+    }
+    *to = 0;
+  }
+  return to - (char16_t*)aString;
+}
+
+/* ***** END RICKG BLOCK ***** */
+
+static const char* kWhitespace="\f\t\r\n ";
+
+// This function is used to implement FindCharInSet and friends
+template <class CharT>
+#ifndef __SUNPRO_CC
+static
+#endif /* !__SUNPRO_CC */
+CharT
+GetFindInSetFilter( const CharT* set)
+{
+  CharT filter = ~CharT(0); // All bits set
+  while (*set) {
+    filter &= ~(*set);
+    ++set;
+  }
+  return filter;
+}
+
+// This template class is used by our code to access rickg's buffer routines.
+template <class CharT> struct nsBufferRoutines {};
+
+template <>
+struct nsBufferRoutines<char>
+{
+  static
+  int32_t compare( const char* a, const char* b, uint32_t max, bool ic )
+  {
+    return Compare1To1(a, b, max, ic);
+  }
+
+  static
+  int32_t compare( const char* a, const char16_t* b, uint32_t max, bool ic )
+  {
+    return Compare1To2(a, b, max, ic);
+  }
+
+  static
+  int32_t find_char( const char* s, uint32_t max, int32_t offset, const char16_t c, int32_t count )
+  {
+    return FindChar1(s, max, offset, c, count);
+  }
+
+  static
+  int32_t rfind_char( const char* s, uint32_t max, int32_t offset, const char16_t c, int32_t count )
+  {
+    return RFindChar1(s, max, offset, c, count);
+  }
+
+  static
+  char get_find_in_set_filter( const char* set )
+  {
+    return GetFindInSetFilter(set);
+  }
+
+  static
+  int32_t strip_chars( char* s, uint32_t len, const char* set )
+  {
+    return StripChars1(s, len, set);
+  }
+
+  static
+  int32_t compress_chars( char* s, uint32_t len, const char* set )
+  {
+    return CompressChars1(s, len, set);
+  }
+};
+
+template <>
+struct nsBufferRoutines<char16_t>
+{
+  static
+  int32_t compare( const char16_t* a, const char16_t* b, uint32_t max, bool ic )
+  {
+    NS_ASSERTION(!ic, "no case-insensitive compare here");
+    return Compare2To2(a, b, max);
+  }
+
+  static
+  int32_t compare( const char16_t* a, const char* b, uint32_t max, bool ic )
+  {
+    return Compare2To1(a, b, max, ic);
+  }
+
+  static
+  int32_t find_char( const char16_t* s, uint32_t max, int32_t offset, const char16_t c, int32_t count )
+  {
+    return FindChar2(s, max, offset, c, count);
+  }
+
+  static
+  int32_t rfind_char( const char16_t* s, uint32_t max, int32_t offset, const char16_t c, int32_t count )
+  {
+    return RFindChar2(s, max, offset, c, count);
+  }
+
+  static
+  char16_t get_find_in_set_filter( const char16_t* set )
+  {
+    return GetFindInSetFilter(set);
+  }
+
+  static
+  char16_t get_find_in_set_filter( const char* set )
+  {
+    return (~char16_t(0)^~char(0)) | GetFindInSetFilter(set);
+  }
+
+  static
+  int32_t strip_chars( char16_t* s, uint32_t max, const char* set )
+  {
+    return StripChars2(s, max, set);
+  }
+
+  static
+  int32_t compress_chars( char16_t* s, uint32_t len, const char* set )
+  {
+    return CompressChars2(s, len, set);
+  }
+};
+
+//-----------------------------------------------------------------------------
+
+template <class L, class R>
+#ifndef __SUNPRO_CC
+static
+#endif /* !__SUNPRO_CC */
+int32_t
+FindSubstring( const L* big, uint32_t bigLen,
+               const R* little, uint32_t littleLen,
+               bool ignoreCase )
+{
+  if (littleLen > bigLen)
+    return kNotFound;
+
+  int32_t i, max = int32_t(bigLen - littleLen);
+  for (i=0; i<=max; ++i, ++big)
+  {
+    if (nsBufferRoutines<L>::compare(big, little, littleLen, ignoreCase) == 0)
+      return i;
+  }
+
+  return kNotFound;
+}
+
+template <class L, class R>
+#ifndef __SUNPRO_CC
+static
+#endif /* !__SUNPRO_CC */
+int32_t
+RFindSubstring( const L* big, uint32_t bigLen,
+                const R* little, uint32_t littleLen,
+                bool ignoreCase )
+{
+  if (littleLen > bigLen)
+    return kNotFound;
+
+  int32_t i, max = int32_t(bigLen - littleLen);
+
+  const L* iter = big + max;
+  for (i=max; iter >= big; --i, --iter)
+  {
+    if (nsBufferRoutines<L>::compare(iter, little, littleLen, ignoreCase) == 0)
+      return i;
+  }
+
+  return kNotFound;
+}
+
+template <class CharT, class SetCharT>
+#ifndef __SUNPRO_CC
+static
+#endif /* !__SUNPRO_CC */
+int32_t
+FindCharInSet( const CharT* data, uint32_t dataLen, const SetCharT* set )
+{
+  CharT filter = nsBufferRoutines<CharT>::get_find_in_set_filter(set);
+
+  const CharT* end = data + dataLen;
+  for (const CharT* iter = data; iter < end; ++iter)
+  {
+    CharT currentChar = *iter;
+    if (currentChar & filter)
+      continue; // char is not in filter set; go on with next char.
+
+    // test all chars
+    const SetCharT* charInSet = set;
+    CharT setChar = CharT(*charInSet);
+    while (setChar)
+    {
+      if (setChar == currentChar)
+        return iter - data; // found it!  return index of the found char.
+
+      setChar = CharT(*(++charInSet));
+    }
+  }
+  return kNotFound;
+}
+
+template <class CharT, class SetCharT>
+#ifndef __SUNPRO_CC
+static
+#endif /* !__SUNPRO_CC */
+int32_t
+RFindCharInSet( const CharT* data, uint32_t dataLen, const SetCharT* set )
+{
+  CharT filter = nsBufferRoutines<CharT>::get_find_in_set_filter(set);
+
+  for (const CharT* iter = data + dataLen - 1; iter >= data; --iter)
+  {
+    CharT currentChar = *iter;
+    if (currentChar & filter)
+      continue; // char is not in filter set; go on with next char.
+
+    // test all chars
+    const CharT* charInSet = set;
+    CharT setChar = *charInSet;
+    while (setChar)
+    {
+      if (setChar == currentChar)
+        return iter - data; // found it!  return index of the found char.
+
+      setChar = *(++charInSet);
+    }
+  }
+  return kNotFound;
+}
+
+/**
+ * this method changes the meaning of |offset| and |count|:
+ *
+ * upon return,
+ *   |offset| specifies start of search range
+ *   |count| specifies length of search range
+ */
+static void
+Find_ComputeSearchRange( uint32_t bigLen, uint32_t littleLen, int32_t& offset, int32_t& count )
+{
+  // |count| specifies how many iterations to make from |offset|
+
+  if (offset < 0)
+  {
+    offset = 0;
+  }
+  else if (uint32_t(offset) > bigLen)
+  {
+    count = 0;
+    return;
+  }
+
+  int32_t maxCount = bigLen - offset;
+  if (count < 0 || count > maxCount)
+  {
+    count = maxCount;
+  }
+  else
+  {
+    count += littleLen;
+    if (count > maxCount)
+      count = maxCount;
+  }
+}
+
+/**
+ * this method changes the meaning of |offset| and |count|:
+ *
+ * upon entry,
+ *   |offset| specifies the end point from which to search backwards
+ *   |count| specifies the number of iterations from |offset|
+ *
+ * upon return,
+ *   |offset| specifies start of search range
+ *   |count| specifies length of search range
+ *
+ *
+ * EXAMPLE
+ *
+ *                            + -- littleLen=4 -- +
+ *                            :                   :
+ *   |____|____|____|____|____|____|____|____|____|____|____|____|
+ *                            :                                  :
+ *                         offset=5                           bigLen=12
+ *
+ *   if count = 4, then we expect this function to return offset = 2 and
+ *   count = 7.
+ *
+ */
+static void
+RFind_ComputeSearchRange( uint32_t bigLen, uint32_t littleLen, int32_t& offset, int32_t& count )
+{
+  if (littleLen > bigLen)
+  {
+    offset = 0;
+    count = 0;
+    return;
+  }
+
+  if (offset < 0)
+    offset = bigLen - littleLen;
+  if (count < 0)
+    count = offset + 1;
+
+  int32_t start = offset - count + 1;
+  if (start < 0)
+    start = 0;
+
+  count = offset + littleLen - start;
+  offset = start;
+}
+
+//-----------------------------------------------------------------------------
+
+// define nsString obsolete methods
+#include "string-template-def-unichar.h"
+#include "nsTStringObsolete.cpp"
+#include "string-template-undef.h"
+
+// define nsCString obsolete methods
+#include "string-template-def-char.h"
+#include "nsTStringObsolete.cpp"
+#include "string-template-undef.h"
+
+//-----------------------------------------------------------------------------
+
+// specialized methods:
+
+int32_t
+nsString::Find( const nsAFlatString& aString, int32_t aOffset, int32_t aCount ) const
+{
+  // this method changes the meaning of aOffset and aCount:
+  Find_ComputeSearchRange(mLength, aString.Length(), aOffset, aCount);
+
+  int32_t result = FindSubstring(mData + aOffset, aCount, static_cast<const char16_t*>(aString.get()), aString.Length(), false);
+  if (result != kNotFound)
+    result += aOffset;
+  return result;
+}
+
+int32_t
+nsString::Find( const char16_t* aString, int32_t aOffset, int32_t aCount ) const
+{
+  return Find(nsDependentString(aString), aOffset, aCount);
+}
+
+int32_t
+nsString::RFind( const nsAFlatString& aString, int32_t aOffset, int32_t aCount ) const
+{
+  // this method changes the meaning of aOffset and aCount:
+  RFind_ComputeSearchRange(mLength, aString.Length(), aOffset, aCount);
+
+  int32_t result = RFindSubstring(mData + aOffset, aCount, static_cast<const char16_t*>(aString.get()), aString.Length(), false);
+  if (result != kNotFound)
+    result += aOffset;
+  return result;
+}
+
+int32_t
+nsString::RFind( const char16_t* aString, int32_t aOffset, int32_t aCount ) const
+{
+  return RFind(nsDependentString(aString), aOffset, aCount);
+}
+
+int32_t
+nsString::FindCharInSet( const char16_t* aSet, int32_t aOffset ) const
+{
+  if (aOffset < 0)
+    aOffset = 0;
+  else if (aOffset >= int32_t(mLength))
+    return kNotFound;
+
+  int32_t result = ::FindCharInSet(mData + aOffset, mLength - aOffset, aSet);
+  if (result != kNotFound)
+    result += aOffset;
+  return result;
+}
+
+void
+nsString::ReplaceChar( const char16_t* aSet, char16_t aNewChar )
+{
+  if (!EnsureMutable()) // XXX do this lazily?
+    AllocFailed(mLength);
+
+  char16_t* data = mData;
+  uint32_t lenRemaining = mLength;
+
+  while (lenRemaining)
+  {
+    int32_t i = ::FindCharInSet(data, lenRemaining, aSet);
+    if (i == kNotFound)
+      break;
+
+    data[i++] = aNewChar;
+    data += i;
+    lenRemaining -= i;
+  }
+}
+
+
+/**
+ * nsTString::Compare,CompareWithConversion,etc.
+ */
+
+int32_t
+nsCString::Compare( const char* aString, bool aIgnoreCase, int32_t aCount ) const
+{
+  uint32_t strLen = char_traits::length(aString);
+
+  int32_t maxCount = int32_t(XPCOM_MIN(mLength, strLen));
+
+  int32_t compareCount;
+  if (aCount < 0 || aCount > maxCount)
+    compareCount = maxCount;
+  else
+    compareCount = aCount;
+
+  int32_t result =
+    nsBufferRoutines<char>::compare(mData, aString, compareCount, aIgnoreCase);
+
+  if (result == 0 &&
+      (aCount < 0 || strLen < uint32_t(aCount) || mLength < uint32_t(aCount)))
+  {
+    // Since the caller didn't give us a length to test, or strings shorter
+    // than aCount, and compareCount characters matched, we have to assume
+    // that the longer string is greater.
+
+    if (mLength != strLen)
+      result = (mLength < strLen) ? -1 : 1;
+  }
+  return result;
+}
+
+bool
+nsString::EqualsIgnoreCase( const char* aString, int32_t aCount ) const
+{
+  uint32_t strLen = nsCharTraits<char>::length(aString);
+
+  int32_t maxCount = int32_t(XPCOM_MIN(mLength, strLen));
+
+  int32_t compareCount;
+  if (aCount < 0 || aCount > maxCount)
+    compareCount = maxCount;
+  else
+    compareCount = aCount;
+
+  int32_t result =
+    nsBufferRoutines<char16_t>::compare(mData, aString, compareCount, true);
+
+  if (result == 0 &&
+      (aCount < 0 || strLen < uint32_t(aCount) || mLength < uint32_t(aCount)))
+  {
+    // Since the caller didn't give us a length to test, or strings shorter
+    // than aCount, and compareCount characters matched, we have to assume
+    // that the longer string is greater.
+
+    if (mLength != strLen)
+      result = 1; // Arbitrarily using any number != 0
+  }
+  return result == 0;
+}
+
+
+/**
+ * nsTString::ToDouble
+ */
+
+double
+nsCString::ToDouble(nsresult* aErrorCode) const
+{
+  double res = 0.0;
+  if (mLength > 0)
+  {
+    char *conv_stopped;
+    const char *str = mData;
+    // Use PR_strtod, not strtod, since we don't want locale involved.
+    res = PR_strtod(str, &conv_stopped);
+    if (conv_stopped == str+mLength)
+      *aErrorCode = NS_OK;
+    else // Not all the string was scanned
+      *aErrorCode = NS_ERROR_ILLEGAL_VALUE;
+  }
+  else
+  {
+    // The string was too short (0 characters)
+    *aErrorCode = NS_ERROR_ILLEGAL_VALUE;
+  }
+  return res;
+}
+
+double
+nsString::ToDouble(nsresult* aErrorCode) const
+{
+  return NS_LossyConvertUTF16toASCII(*this).ToDouble(aErrorCode);
+}
+
+
+/**
+ * nsTString::AssignWithConversion
+ */
+
+void
+nsCString::AssignWithConversion( const nsAString& aData )
+{
+  LossyCopyUTF16toASCII(aData, *this);
+}
+
+void
+nsString::AssignWithConversion( const nsACString& aData )
+{
+  CopyASCIItoUTF16(aData, *this);
+}
+
+#endif // !MOZ_STRING_WITH_OBSOLETE_API
diff --git a/xpcom/string/nsSubstring.cpp b/xpcom/string/nsSubstring.cpp
new file mode 100644
index 000000000..5bc69f741
--- /dev/null
+++ b/xpcom/string/nsSubstring.cpp
@@ -0,0 +1,388 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifdef DEBUG
+#define ENABLE_STRING_STATS
+#endif
+
+#include "mozilla/Atomics.h"
+#include "mozilla/MemoryReporting.h"
+
+#ifdef ENABLE_STRING_STATS
+#include <stdio.h>
+#endif
+
+#include <stdlib.h>
+#include "nsSubstring.h"
+#include "nsString.h"
+#include "nsStringBuffer.h"
+#include "nsDependentString.h"
+#include "nsMemory.h"
+#include "prprf.h"
+#include "nsStaticAtom.h"
+#include "nsCOMPtr.h"
+
+#include "mozilla/IntegerPrintfMacros.h"
+#ifdef XP_WIN
+#include <windows.h>
+#include <process.h>
+#define getpid() _getpid()
+#define pthread_self() GetCurrentThreadId()
+#else
+#include <pthread.h>
+#include <unistd.h>
+#endif
+
+using mozilla::Atomic;
+
+// ---------------------------------------------------------------------------
+
+static const char16_t gNullChar = 0;
+
+char* const nsCharTraits<char>::sEmptyBuffer =
+  (char*)const_cast<char16_t*>(&gNullChar);
+char16_t* const nsCharTraits<char16_t>::sEmptyBuffer =
+  const_cast<char16_t*>(&gNullChar);
+
+// ---------------------------------------------------------------------------
+
+#ifdef ENABLE_STRING_STATS
+class nsStringStats
+{
+public:
+  nsStringStats()
+    : mAllocCount(0)
+    , mReallocCount(0)
+    , mFreeCount(0)
+    , mShareCount(0)
+  {
+  }
+
+  ~nsStringStats()
+  {
+    // this is a hack to suppress duplicate string stats printing
+    // in seamonkey as a result of the string code being linked
+    // into seamonkey and libxpcom! :-(
+    if (!mAllocCount && !mAdoptCount) {
+      return;
+    }
+
+    printf("nsStringStats\n");
+    printf(" => mAllocCount:     % 10d\n", int(mAllocCount));
+    printf(" => mReallocCount:   % 10d\n", int(mReallocCount));
+    printf(" => mFreeCount:      % 10d", int(mFreeCount));
+    if (mAllocCount > mFreeCount) {
+      printf("  --  LEAKED %d !!!\n", mAllocCount - mFreeCount);
+    } else {
+      printf("\n");
+    }
+    printf(" => mShareCount:     % 10d\n", int(mShareCount));
+    printf(" => mAdoptCount:     % 10d\n", int(mAdoptCount));
+    printf(" => mAdoptFreeCount: % 10d", int(mAdoptFreeCount));
+    if (mAdoptCount > mAdoptFreeCount) {
+      printf("  --  LEAKED %d !!!\n", mAdoptCount - mAdoptFreeCount);
+    } else {
+      printf("\n");
+    }
+    printf(" => Process ID: %" PRIuPTR ", Thread ID: %" PRIuPTR "\n",
+           uintptr_t(getpid()), uintptr_t(pthread_self()));
+  }
+
+  Atomic<int32_t> mAllocCount;
+  Atomic<int32_t> mReallocCount;
+  Atomic<int32_t> mFreeCount;
+  Atomic<int32_t> mShareCount;
+  Atomic<int32_t> mAdoptCount;
+  Atomic<int32_t> mAdoptFreeCount;
+};
+static nsStringStats gStringStats;
+#define STRING_STAT_INCREMENT(_s) (gStringStats.m ## _s ## Count)++
+#else
+#define STRING_STAT_INCREMENT(_s)
+#endif
+
+// ---------------------------------------------------------------------------
+
+void
+ReleaseData(void* aData, uint32_t aFlags)
+{
+  if (aFlags & nsSubstring::F_SHARED) {
+    nsStringBuffer::FromData(aData)->Release();
+  } else if (aFlags & nsSubstring::F_OWNED) {
+    free(aData);
+    STRING_STAT_INCREMENT(AdoptFree);
+    // Treat this as destruction of a "StringAdopt" object for leak
+    // tracking purposes.
+    MOZ_LOG_DTOR(aData, "StringAdopt", 1);
+  }
+  // otherwise, nothing to do.
+}
+
+// ---------------------------------------------------------------------------
+
+// XXX or we could make nsStringBuffer be a friend of nsTAString
+
+class nsAStringAccessor : public nsAString
+{
+private:
+  nsAStringAccessor(); // NOT IMPLEMENTED
+
+public:
+  char_type* data() const
+  {
+    return mData;
+  }
+  size_type length() const
+  {
+    return mLength;
+  }
+  uint32_t flags() const
+  {
+    return mFlags;
+  }
+
+  void set(char_type* aData, size_type aLen, uint32_t aFlags)
+  {
+    ReleaseData(mData, mFlags);
+    mData = aData;
+    mLength = aLen;
+    mFlags = aFlags;
+  }
+};
+
+class nsACStringAccessor : public nsACString
+{
+private:
+  nsACStringAccessor(); // NOT IMPLEMENTED
+
+public:
+  char_type* data() const
+  {
+    return mData;
+  }
+  size_type length() const
+  {
+    return mLength;
+  }
+  uint32_t flags() const
+  {
+    return mFlags;
+  }
+
+  void set(char_type* aData, size_type aLen, uint32_t aFlags)
+  {
+    ReleaseData(mData, mFlags);
+    mData = aData;
+    mLength = aLen;
+    mFlags = aFlags;
+  }
+};
+
+// ---------------------------------------------------------------------------
+
+void
+nsStringBuffer::AddRef()
+{
+  ++mRefCount;
+  STRING_STAT_INCREMENT(Share);
+  NS_LOG_ADDREF(this, mRefCount, "nsStringBuffer", sizeof(*this));
+}
+
+void
+nsStringBuffer::Release()
+{
+  int32_t count = --mRefCount;
+  NS_LOG_RELEASE(this, count, "nsStringBuffer");
+  if (count == 0) {
+    STRING_STAT_INCREMENT(Free);
+    free(this); // we were allocated with |malloc|
+  }
+}
+
+/**
+ * Alloc returns a pointer to a new string header with set capacity.
+ */
+already_AddRefed<nsStringBuffer>
+nsStringBuffer::Alloc(size_t aSize)
+{
+  NS_ASSERTION(aSize != 0, "zero capacity allocation not allowed");
+  NS_ASSERTION(sizeof(nsStringBuffer) + aSize <= size_t(uint32_t(-1)) &&
+               sizeof(nsStringBuffer) + aSize > aSize,
+               "mStorageSize will truncate");
+
+  nsStringBuffer* hdr =
+    (nsStringBuffer*)malloc(sizeof(nsStringBuffer) + aSize);
+  if (hdr) {
+    STRING_STAT_INCREMENT(Alloc);
+
+    hdr->mRefCount = 1;
+    hdr->mStorageSize = aSize;
+    NS_LOG_ADDREF(hdr, 1, "nsStringBuffer", sizeof(*hdr));
+  }
+  return dont_AddRef(hdr);
+}
+
+nsStringBuffer*
+nsStringBuffer::Realloc(nsStringBuffer* aHdr, size_t aSize)
+{
+  STRING_STAT_INCREMENT(Realloc);
+
+  NS_ASSERTION(aSize != 0, "zero capacity allocation not allowed");
+  NS_ASSERTION(sizeof(nsStringBuffer) + aSize <= size_t(uint32_t(-1)) &&
+               sizeof(nsStringBuffer) + aSize > aSize,
+               "mStorageSize will truncate");
+
+  // no point in trying to save ourselves if we hit this assertion
+  NS_ASSERTION(!aHdr->IsReadonly(), "|Realloc| attempted on readonly string");
+
+  // Treat this as a release and addref for refcounting purposes, since we
+  // just asserted that the refcount is 1.  If we don't do that, refcount
+  // logging will claim we've leaked all sorts of stuff.
+  NS_LOG_RELEASE(aHdr, 0, "nsStringBuffer");
+
+  aHdr = (nsStringBuffer*)realloc(aHdr, sizeof(nsStringBuffer) + aSize);
+  if (aHdr) {
+    NS_LOG_ADDREF(aHdr, 1, "nsStringBuffer", sizeof(*aHdr));
+    aHdr->mStorageSize = aSize;
+  }
+
+  return aHdr;
+}
+
+nsStringBuffer*
+nsStringBuffer::FromString(const nsAString& aStr)
+{
+  const nsAStringAccessor* accessor =
+    static_cast<const nsAStringAccessor*>(&aStr);
+
+  if (!(accessor->flags() & nsSubstring::F_SHARED)) {
+    return nullptr;
+  }
+
+  return FromData(accessor->data());
+}
+
+nsStringBuffer*
+nsStringBuffer::FromString(const nsACString& aStr)
+{
+  const nsACStringAccessor* accessor =
+    static_cast<const nsACStringAccessor*>(&aStr);
+
+  if (!(accessor->flags() & nsCSubstring::F_SHARED)) {
+    return nullptr;
+  }
+
+  return FromData(accessor->data());
+}
+
+void
+nsStringBuffer::ToString(uint32_t aLen, nsAString& aStr,
+                         bool aMoveOwnership)
+{
+  char16_t* data = static_cast<char16_t*>(Data());
+
+  nsAStringAccessor* accessor = static_cast<nsAStringAccessor*>(&aStr);
+  MOZ_DIAGNOSTIC_ASSERT(data[aLen] == char16_t(0),
+                        "data should be null terminated");
+
+  // preserve class flags
+  uint32_t flags = accessor->flags();
+  flags = (flags & 0xFFFF0000) | nsSubstring::F_SHARED | nsSubstring::F_TERMINATED;
+
+  if (!aMoveOwnership) {
+    AddRef();
+  }
+  accessor->set(data, aLen, flags);
+}
+
+void
+nsStringBuffer::ToString(uint32_t aLen, nsACString& aStr,
+                         bool aMoveOwnership)
+{
+  char* data = static_cast<char*>(Data());
+
+  nsACStringAccessor* accessor = static_cast<nsACStringAccessor*>(&aStr);
+  MOZ_DIAGNOSTIC_ASSERT(data[aLen] == char(0),
+                        "data should be null terminated");
+
+  // preserve class flags
+  uint32_t flags = accessor->flags();
+  flags = (flags & 0xFFFF0000) | nsCSubstring::F_SHARED | nsCSubstring::F_TERMINATED;
+
+  if (!aMoveOwnership) {
+    AddRef();
+  }
+  accessor->set(data, aLen, flags);
+}
+
+size_t
+nsStringBuffer::SizeOfIncludingThisIfUnshared(mozilla::MallocSizeOf aMallocSizeOf) const
+{
+  return IsReadonly() ? 0 : aMallocSizeOf(this);
+}
+
+size_t
+nsStringBuffer::SizeOfIncludingThisEvenIfShared(mozilla::MallocSizeOf aMallocSizeOf) const
+{
+  return aMallocSizeOf(this);
+}
+
+// ---------------------------------------------------------------------------
+
+
+// define nsSubstring
+#include "string-template-def-unichar.h"
+#include "nsTSubstring.cpp"
+#include "string-template-undef.h"
+
+// define nsCSubstring
+#include "string-template-def-char.h"
+#include "nsTSubstring.cpp"
+#include "string-template-undef.h"
+
+// Check that internal and external strings have the same size.
+// See https://bugzilla.mozilla.org/show_bug.cgi?id=430581
+
+#include "mozilla/Logging.h"
+#include "nsXPCOMStrings.h"
+
+static_assert(sizeof(nsStringContainer_base) == sizeof(nsSubstring),
+              "internal and external strings must have the same size");
+
+// Provide rust bindings to the nsA[C]String types
+extern "C" {
+
+void Gecko_FinalizeCString(nsACString* aThis)
+{
+  aThis->~nsACString();
+}
+
+void Gecko_AssignCString(nsACString* aThis, const nsACString* aOther)
+{
+  aThis->Assign(*aOther);
+}
+
+void Gecko_AppendCString(nsACString* aThis, const nsACString* aOther)
+{
+  aThis->Append(*aOther);
+}
+
+void Gecko_FinalizeString(nsAString* aThis)
+{
+  aThis->~nsAString();
+}
+
+void Gecko_AssignString(nsAString* aThis, const nsAString* aOther)
+{
+  aThis->Assign(*aOther);
+}
+
+void Gecko_AppendString(nsAString* aThis, const nsAString* aOther)
+{
+  aThis->Append(*aOther);
+}
+
+} // extern "C"
diff --git a/xpcom/string/nsSubstring.h b/xpcom/string/nsSubstring.h
new file mode 100644
index 000000000..67125ba31
--- /dev/null
+++ b/xpcom/string/nsSubstring.h
@@ -0,0 +1,12 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSubstring_h___
+#define nsSubstring_h___
+
+#include "nsAString.h"
+
+#endif // !defined(nsSubstring_h___)
diff --git a/xpcom/string/nsSubstringTuple.cpp b/xpcom/string/nsSubstringTuple.cpp
new file mode 100644
index 000000000..3de928dda
--- /dev/null
+++ b/xpcom/string/nsSubstringTuple.cpp
@@ -0,0 +1,20 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsSubstringTuple.h"
+
+// convert fragment to |const substring_type&|
+#define TO_SUBSTRING(_v) (*(_v))
+
+// define nsSubstringTuple
+#include "string-template-def-unichar.h"
+#include "nsTSubstringTuple.cpp"
+#include "string-template-undef.h"
+
+// define nsCSubstringTuple
+#include "string-template-def-char.h"
+#include "nsTSubstringTuple.cpp"
+#include "string-template-undef.h"
diff --git a/xpcom/string/nsSubstringTuple.h b/xpcom/string/nsSubstringTuple.h
new file mode 100644
index 000000000..5a61cd831
--- /dev/null
+++ b/xpcom/string/nsSubstringTuple.h
@@ -0,0 +1,22 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSubstringTuple_h___
+#define nsSubstringTuple_h___
+
+#include "nsSubstring.h"
+
+// declare nsSubstringTuple
+#include "string-template-def-unichar.h"
+#include "nsTSubstringTuple.h"
+#include "string-template-undef.h"
+
+// declare nsCSubstringTuple
+#include "string-template-def-char.h"
+#include "nsTSubstringTuple.h"
+#include "string-template-undef.h"
+
+#endif // !defined(nsSubstringTuple_h___)
diff --git a/xpcom/string/nsTDependentString.cpp b/xpcom/string/nsTDependentString.cpp
new file mode 100644
index 000000000..2f3a095d1
--- /dev/null
+++ b/xpcom/string/nsTDependentString.cpp
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+void
+nsTDependentString_CharT::Rebind(const string_type& str, uint32_t startPos)
+{
+  MOZ_ASSERT(str.Flags() & F_TERMINATED, "Unterminated flat string");
+
+  // If we currently own a buffer, release it.
+  Finalize();
+
+  size_type strLength = str.Length();
+
+  if (startPos > strLength) {
+    startPos = strLength;
+  }
+
+  mData = const_cast<char_type*>(static_cast<const char_type*>(str.Data())) + startPos;
+  mLength = strLength - startPos;
+
+  SetDataFlags(str.Flags() & (F_TERMINATED | F_LITERAL));
+}
diff --git a/xpcom/string/nsTDependentString.h b/xpcom/string/nsTDependentString.h
new file mode 100644
index 000000000..44055d5ac
--- /dev/null
+++ b/xpcom/string/nsTDependentString.h
@@ -0,0 +1,106 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+/**
+ * nsTDependentString_CharT
+ *
+ * Stores a null-terminated, immutable sequence of characters.
+ *
+ * Subclass of nsTString that restricts string value to an immutable
+ * character sequence.  This class does not own its data, so the creator
+ * of objects of this type must take care to ensure that a
+ * nsTDependentString continues to reference valid memory for the
+ * duration of its use.
+ */
+class nsTDependentString_CharT : public nsTString_CharT
+{
+public:
+
+  typedef nsTDependentString_CharT self_type;
+
+public:
+
+  /**
+   * constructors
+   */
+
+  nsTDependentString_CharT(const char_type* aStart, const char_type* aEnd)
+    : string_type(const_cast<char_type*>(aStart),
+                  uint32_t(aEnd - aStart), F_TERMINATED)
+  {
+    AssertValidDependentString();
+  }
+
+  nsTDependentString_CharT(const char_type* aData, uint32_t aLength)
+    : string_type(const_cast<char_type*>(aData), aLength, F_TERMINATED)
+  {
+    AssertValidDependentString();
+  }
+
+#if defined(CharT_is_PRUnichar) && defined(MOZ_USE_CHAR16_WRAPPER)
+  nsTDependentString_CharT(char16ptr_t aData, uint32_t aLength)
+    : nsTDependentString_CharT(static_cast<const char16_t*>(aData), aLength)
+  {
+  }
+#endif
+
+  explicit
+  nsTDependentString_CharT(const char_type* aData)
+    : string_type(const_cast<char_type*>(aData),
+                  uint32_t(char_traits::length(aData)), F_TERMINATED)
+  {
+    AssertValidDependentString();
+  }
+
+#if defined(CharT_is_PRUnichar) && defined(MOZ_USE_CHAR16_WRAPPER)
+  explicit
+  nsTDependentString_CharT(char16ptr_t aData)
+    : nsTDependentString_CharT(static_cast<const char16_t*>(aData))
+  {
+  }
+#endif
+
+  nsTDependentString_CharT(const string_type& aStr, uint32_t aStartPos)
+    : string_type()
+  {
+    Rebind(aStr, aStartPos);
+  }
+
+  // Create a nsTDependentSubstring to be bound later
+  nsTDependentString_CharT()
+    : string_type()
+  {
+  }
+
+  // XXX are you sure??
+  // auto-generated copy-constructor OK
+  // auto-generated copy-assignment operator OK
+  // auto-generated destructor OK
+
+
+  /**
+   * allow this class to be bound to a different string...
+   */
+
+  using nsTString_CharT::Rebind;
+  void Rebind(const char_type* aData)
+  {
+    Rebind(aData, uint32_t(char_traits::length(aData)));
+  }
+
+  void Rebind(const char_type* aStart, const char_type* aEnd)
+  {
+    Rebind(aStart, uint32_t(aEnd - aStart));
+  }
+
+  void Rebind(const string_type&, uint32_t aStartPos);
+
+private:
+
+  // NOT USED
+  nsTDependentString_CharT(const substring_tuple_type&) = delete;
+};
diff --git a/xpcom/string/nsTDependentSubstring.cpp b/xpcom/string/nsTDependentSubstring.cpp
new file mode 100644
index 000000000..b540c028d
--- /dev/null
+++ b/xpcom/string/nsTDependentSubstring.cpp
@@ -0,0 +1,37 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+void
+nsTDependentSubstring_CharT::Rebind(const substring_type& str,
+                                    uint32_t startPos, uint32_t length)
+{
+  // If we currently own a buffer, release it.
+  Finalize();
+
+  size_type strLength = str.Length();
+
+  if (startPos > strLength) {
+    startPos = strLength;
+  }
+
+  mData = const_cast<char_type*>(static_cast<const char_type*>(str.Data())) + startPos;
+  mLength = XPCOM_MIN(length, strLength - startPos);
+
+  SetDataFlags(F_NONE);
+}
+
+void
+nsTDependentSubstring_CharT::Rebind(const char_type* data, size_type length)
+{
+  NS_ASSERTION(data, "nsTDependentSubstring must wrap a non-NULL buffer");
+
+  // If we currently own a buffer, release it.
+  Finalize();
+
+  mData = const_cast<char_type*>(static_cast<const char_type*>(data));
+  mLength = length;
+  SetDataFlags(F_NONE);
+}
diff --git a/xpcom/string/nsTDependentSubstring.h b/xpcom/string/nsTDependentSubstring.h
new file mode 100644
index 000000000..dd28f32f9
--- /dev/null
+++ b/xpcom/string/nsTDependentSubstring.h
@@ -0,0 +1,124 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+// IWYU pragma: private, include "nsString.h"
+
+/**
+ * nsTDependentSubstring_CharT
+ *
+ * A string class which wraps an external array of string characters. It
+ * is the client code's responsibility to ensure that the external buffer
+ * remains valid for a long as the string is alive.
+ *
+ * NAMES:
+ *   nsDependentSubstring for wide characters
+ *   nsDependentCSubstring for narrow characters
+ */
+class nsTDependentSubstring_CharT : public nsTSubstring_CharT
+{
+public:
+
+  typedef nsTDependentSubstring_CharT self_type;
+
+public:
+
+  void Rebind(const substring_type&, uint32_t aStartPos,
+              uint32_t aLength = size_type(-1));
+
+  void Rebind(const char_type* aData, size_type aLength);
+
+  void Rebind(const char_type* aStart, const char_type* aEnd)
+  {
+    Rebind(aStart, size_type(aEnd - aStart));
+  }
+
+  nsTDependentSubstring_CharT(const substring_type& aStr, uint32_t aStartPos,
+                              uint32_t aLength = size_type(-1))
+    : substring_type()
+  {
+    Rebind(aStr, aStartPos, aLength);
+  }
+
+  nsTDependentSubstring_CharT(const char_type* aData, size_type aLength)
+    : substring_type(const_cast<char_type*>(aData), aLength, F_NONE)
+  {
+  }
+
+  nsTDependentSubstring_CharT(const char_type* aStart, const char_type* aEnd)
+    : substring_type(const_cast<char_type*>(aStart), uint32_t(aEnd - aStart),
+                     F_NONE)
+  {
+  }
+
+#if defined(CharT_is_PRUnichar) && defined(MOZ_USE_CHAR16_WRAPPER)
+  nsTDependentSubstring_CharT(char16ptr_t aData, size_type aLength)
+    : nsTDependentSubstring_CharT(static_cast<const char16_t*>(aData), aLength)
+  {
+  }
+
+  nsTDependentSubstring_CharT(char16ptr_t aStart, char16ptr_t aEnd)
+    : nsTDependentSubstring_CharT(static_cast<const char16_t*>(aStart),
+                                  static_cast<const char16_t*>(aEnd))
+  {
+  }
+#endif
+
+  nsTDependentSubstring_CharT(const const_iterator& aStart,
+                              const const_iterator& aEnd)
+    : substring_type(const_cast<char_type*>(aStart.get()),
+                     uint32_t(aEnd.get() - aStart.get()), F_NONE)
+  {
+  }
+
+  // Create a nsTDependentSubstring to be bound later
+  nsTDependentSubstring_CharT()
+    : substring_type()
+  {
+  }
+
+  // auto-generated copy-constructor OK (XXX really?? what about base class copy-ctor?)
+
+private:
+  // NOT USED
+  void operator=(const self_type&);  // we're immutable, you can't assign into a substring
+};
+
+inline const nsTDependentSubstring_CharT
+Substring(const nsTSubstring_CharT& aStr, uint32_t aStartPos,
+          uint32_t aLength = uint32_t(-1))
+{
+  return nsTDependentSubstring_CharT(aStr, aStartPos, aLength);
+}
+
+inline const nsTDependentSubstring_CharT
+Substring(const nsReadingIterator<CharT>& aStart,
+          const nsReadingIterator<CharT>& aEnd)
+{
+  return nsTDependentSubstring_CharT(aStart.get(), aEnd.get());
+}
+
+inline const nsTDependentSubstring_CharT
+Substring(const CharT* aData, uint32_t aLength)
+{
+  return nsTDependentSubstring_CharT(aData, aLength);
+}
+
+inline const nsTDependentSubstring_CharT
+Substring(const CharT* aStart, const CharT* aEnd)
+{
+  return nsTDependentSubstring_CharT(aStart, aEnd);
+}
+
+inline const nsTDependentSubstring_CharT
+StringHead(const nsTSubstring_CharT& aStr, uint32_t aCount)
+{
+  return nsTDependentSubstring_CharT(aStr, 0, aCount);
+}
+
+inline const nsTDependentSubstring_CharT
+StringTail(const nsTSubstring_CharT& aStr, uint32_t aCount)
+{
+  return nsTDependentSubstring_CharT(aStr, aStr.Length() - aCount, aCount);
+}
diff --git a/xpcom/string/nsTLiteralString.h b/xpcom/string/nsTLiteralString.h
new file mode 100644
index 000000000..fa75ba829
--- /dev/null
+++ b/xpcom/string/nsTLiteralString.h
@@ -0,0 +1,41 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+/**
+ * nsTLiteralString_CharT
+ *
+ * Stores a null-terminated, immutable sequence of characters.
+ *
+ * Subclass of nsTString that restricts string value to a literal
+ * character sequence.  This class does not own its data. The data is
+ * assumed to be permanent. In practice this is true because this code
+ * is only usable by and for libxul.
+ */
+class nsTLiteralString_CharT : public nsTString_CharT
+{
+public:
+
+  typedef nsTLiteralString_CharT self_type;
+
+public:
+
+  /**
+   * constructor
+   */
+
+  template<size_type N>
+  explicit nsTLiteralString_CharT(const char_type (&aStr)[N])
+    : string_type(const_cast<char_type*>(aStr), N - 1, F_TERMINATED | F_LITERAL)
+  {
+  }
+
+private:
+
+  // NOT TO BE IMPLEMENTED
+  template<size_type N>
+  nsTLiteralString_CharT(char_type (&aStr)[N]) = delete;
+};
diff --git a/xpcom/string/nsTPromiseFlatString.cpp b/xpcom/string/nsTPromiseFlatString.cpp
new file mode 100644
index 000000000..f02fc925c
--- /dev/null
+++ b/xpcom/string/nsTPromiseFlatString.cpp
@@ -0,0 +1,18 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+void
+nsTPromiseFlatString_CharT::Init(const substring_type& str)
+{
+  if (str.IsTerminated()) {
+    mData = const_cast<char_type*>(static_cast<const char_type*>(str.Data()));
+    mLength = str.Length();
+    mFlags = str.mFlags & (F_TERMINATED | F_LITERAL);
+    // does not promote F_VOIDED
+  } else {
+    Assign(str);
+  }
+}
diff --git a/xpcom/string/nsTPromiseFlatString.h b/xpcom/string/nsTPromiseFlatString.h
new file mode 100644
index 000000000..d71ce148d
--- /dev/null
+++ b/xpcom/string/nsTPromiseFlatString.h
@@ -0,0 +1,112 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+/**
+ * NOTE:
+ *
+ * Try to avoid flat strings.  |PromiseFlat[C]String| will help you as a last
+ * resort, and this may be necessary when dealing with legacy or OS calls,
+ * but in general, requiring a null-terminated array of characters kills many
+ * of the performance wins the string classes offer.  Write your own code to
+ * use |nsA[C]String&|s for parameters.  Write your string proccessing
+ * algorithms to exploit iterators.  If you do this, you will benefit from
+ * being able to chain operations without copying or allocating and your code
+ * will be significantly more efficient.  Remember, a function that takes an
+ * |const nsA[C]String&| can always be passed a raw character pointer by
+ * wrapping it (for free) in a |nsDependent[C]String|.  But a function that
+ * takes a character pointer always has the potential to force allocation and
+ * copying.
+ *
+ *
+ * How to use it:
+ *
+ * A |nsPromiseFlat[C]String| doesn't necessarily own the characters it
+ * promises.  You must never use it to promise characters out of a string
+ * with a shorter lifespan.  The typical use will be something like this:
+ *
+ *   SomeOSFunction( PromiseFlatCString(aCSubstring).get() ); // GOOD
+ *
+ * Here's a BAD use:
+ *
+ *  const char* buffer = PromiseFlatCString(aCSubstring).get();
+ *  SomeOSFunction(buffer); // BAD!! |buffer| is a dangling pointer
+ *
+ * The only way to make one is with the function |PromiseFlat[C]String|,
+ * which produce a |const| instance.  ``What if I need to keep a promise
+ * around for a little while?'' you might ask.  In that case, you can keep a
+ * reference, like so:
+ *
+ *   const nsCString& flat = PromiseFlatString(aCSubstring);
+ *     // Temporaries usually die after the full expression containing the
+ *     // expression that created the temporary is evaluated.  But when a
+ *     // temporary is assigned to a local reference, the temporary's lifetime
+ *     // is extended to the reference's lifetime (C++11 [class.temporary]p5).
+ *     //
+ *     // This reference holds the anonymous temporary alive.  But remember: it
+ *     // must _still_ have a lifetime shorter than that of |aCSubstring|, and
+ *     // |aCSubstring| must not be changed while the PromiseFlatString lives.
+ *
+ *  SomeOSFunction(flat.get());
+ *  SomeOtherOSFunction(flat.get());
+ *
+ *
+ * How does it work?
+ *
+ * A |nsPromiseFlat[C]String| is just a wrapper for another string.  If you
+ * apply it to a string that happens to be flat, your promise is just a
+ * dependent reference to the string's data.  If you apply it to a non-flat
+ * string, then a temporary flat string is created for you, by allocating and
+ * copying.  In the event that you end up assigning the result into a sharing
+ * string (e.g., |nsTString|), the right thing happens.
+ */
+
+class nsTPromiseFlatString_CharT : public nsTString_CharT
+{
+public:
+
+  typedef nsTPromiseFlatString_CharT self_type;
+
+private:
+
+  void Init(const substring_type&);
+
+  // NOT TO BE IMPLEMENTED
+  void operator=(const self_type&) = delete;
+
+  // NOT TO BE IMPLEMENTED
+  nsTPromiseFlatString_CharT() = delete;
+
+  // NOT TO BE IMPLEMENTED
+  nsTPromiseFlatString_CharT(const string_type& aStr) = delete;
+
+public:
+
+  explicit
+  nsTPromiseFlatString_CharT(const substring_type& aStr)
+    : string_type()
+  {
+    Init(aStr);
+  }
+
+  explicit
+  nsTPromiseFlatString_CharT(const substring_tuple_type& aTuple)
+    : string_type()
+  {
+    // nothing else to do here except assign the value of the tuple
+    // into ourselves.
+    Assign(aTuple);
+  }
+};
+
+// We template this so that the constructor is chosen based on the type of the
+// parameter. This allows us to reject attempts to promise a flat flat string.
+template<class T>
+const nsTPromiseFlatString_CharT
+TPromiseFlatString_CharT(const T& aString)
+{
+  return nsTPromiseFlatString_CharT(aString);
+}
diff --git a/xpcom/string/nsTString.cpp b/xpcom/string/nsTString.cpp
new file mode 100644
index 000000000..13dd2628e
--- /dev/null
+++ b/xpcom/string/nsTString.cpp
@@ -0,0 +1,47 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+nsTAdoptingString_CharT&
+nsTAdoptingString_CharT::operator=(const self_type& str)
+{
+  // This'll violate the constness of this argument, that's just
+  // the nature of this class...
+  self_type* mutable_str = const_cast<self_type*>(&str);
+
+  if (str.mFlags & F_OWNED) {
+    // We want to do what Adopt() does, but without actually incrementing
+    // the Adopt count.  Note that we can be a little more straightforward
+    // about this than Adopt() is, because we know that str.mData is
+    // non-null.  Should we be able to assert that str is not void here?
+    NS_ASSERTION(str.mData, "String with null mData?");
+    Finalize();
+    mData = str.mData;
+    mLength = str.mLength;
+    SetDataFlags(F_TERMINATED | F_OWNED);
+
+    // Make str forget the buffer we just took ownership of.
+    new (mutable_str) self_type();
+  } else {
+    Assign(str);
+
+    mutable_str->Truncate();
+  }
+
+  return *this;
+}
+
+void
+nsTString_CharT::Rebind(const char_type* data, size_type length)
+{
+  // If we currently own a buffer, release it.
+  Finalize();
+
+  mData = const_cast<char_type*>(data);
+  mLength = length;
+  SetDataFlags(F_TERMINATED);
+  AssertValidDependentString();
+}
+
diff --git a/xpcom/string/nsTString.h b/xpcom/string/nsTString.h
new file mode 100644
index 000000000..6fbb9d3ad
--- /dev/null
+++ b/xpcom/string/nsTString.h
@@ -0,0 +1,883 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+// IWYU pragma: private, include "nsString.h"
+
+/**
+ * This is the canonical null-terminated string class.  All subclasses
+ * promise null-terminated storage.  Instances of this class allocate
+ * strings on the heap.
+ *
+ * NAMES:
+ *   nsString for wide characters
+ *   nsCString for narrow characters
+ *
+ * This class is also known as nsAFlat[C]String, where "flat" is used
+ * to denote a null-terminated string.
+ */
+class nsTString_CharT : public nsTSubstring_CharT
+{
+public:
+
+  typedef nsTString_CharT self_type;
+
+public:
+
+  /**
+   * constructors
+   */
+
+  nsTString_CharT()
+    : substring_type()
+  {
+  }
+
+  explicit
+  nsTString_CharT(const char_type* aData, size_type aLength = size_type(-1))
+    : substring_type()
+  {
+    Assign(aData, aLength);
+  }
+
+#if defined(CharT_is_PRUnichar) && defined(MOZ_USE_CHAR16_WRAPPER)
+  explicit
+  nsTString_CharT(char16ptr_t aStr, size_type aLength = size_type(-1))
+    : substring_type()
+  {
+    Assign(static_cast<const char16_t*>(aStr), aLength);
+  }
+#endif
+
+  nsTString_CharT(const self_type& aStr)
+    : substring_type()
+  {
+    Assign(aStr);
+  }
+
+  MOZ_IMPLICIT nsTString_CharT(const substring_tuple_type& aTuple)
+    : substring_type()
+  {
+    Assign(aTuple);
+  }
+
+  explicit
+  nsTString_CharT(const substring_type& aReadable)
+    : substring_type()
+  {
+    Assign(aReadable);
+  }
+
+
+  // |operator=| does not inherit, so we must define our own
+  self_type& operator=(char_type aChar)
+  {
+    Assign(aChar);
+    return *this;
+  }
+  self_type& operator=(const char_type* aData)
+  {
+    Assign(aData);
+    return *this;
+  }
+  self_type& operator=(const self_type& aStr)
+  {
+    Assign(aStr);
+    return *this;
+  }
+#if defined(CharT_is_PRUnichar) && defined(MOZ_USE_CHAR16_WRAPPER)
+  self_type& operator=(const char16ptr_t aStr)
+  {
+    Assign(static_cast<const char16_t*>(aStr));
+    return *this;
+  }
+#endif
+  self_type& operator=(const substring_type& aStr)
+  {
+    Assign(aStr);
+    return *this;
+  }
+  self_type& operator=(const substring_tuple_type& aTuple)
+  {
+    Assign(aTuple);
+    return *this;
+  }
+
+  /**
+   * returns the null-terminated string
+   */
+
+#if defined(CharT_is_PRUnichar) && defined(MOZ_USE_CHAR16_WRAPPER)
+  char16ptr_t get() const
+#else
+  const char_type* get() const
+#endif
+  {
+    return mData;
+  }
+
+
+  /**
+   * returns character at specified index.
+   *
+   * NOTE: unlike nsTSubstring::CharAt, this function allows you to index
+   *       the null terminator character.
+   */
+
+  char_type CharAt(index_type aIndex) const
+  {
+    NS_ASSERTION(aIndex <= mLength, "index exceeds allowable range");
+    return mData[aIndex];
+  }
+
+  char_type operator[](index_type aIndex) const
+  {
+    return CharAt(aIndex);
+  }
+
+
+#if MOZ_STRING_WITH_OBSOLETE_API
+
+
+  /**
+   *  Search for the given substring within this string.
+   *
+   *  @param   aString is substring to be sought in this
+   *  @param   aIgnoreCase selects case sensitivity
+   *  @param   aOffset tells us where in this string to start searching
+   *  @param   aCount tells us how far from the offset we are to search. Use
+   *           -1 to search the whole string.
+   *  @return  offset in string, or kNotFound
+   */
+
+  int32_t Find(const nsCString& aString, bool aIgnoreCase = false,
+               int32_t aOffset = 0, int32_t aCount = -1) const;
+  int32_t Find(const char* aString, bool aIgnoreCase = false,
+               int32_t aOffset = 0, int32_t aCount = -1) const;
+
+#ifdef CharT_is_PRUnichar
+  int32_t Find(const nsAFlatString& aString, int32_t aOffset = 0,
+               int32_t aCount = -1) const;
+  int32_t Find(const char16_t* aString, int32_t aOffset = 0,
+               int32_t aCount = -1) const;
+#ifdef MOZ_USE_CHAR16_WRAPPER
+  int32_t Find(char16ptr_t aString, int32_t aOffset = 0,
+               int32_t aCount = -1) const
+  {
+    return Find(static_cast<const char16_t*>(aString), aOffset, aCount);
+  }
+#endif
+#endif
+
+
+  /**
+   * This methods scans the string backwards, looking for the given string
+   *
+   * @param   aString is substring to be sought in this
+   * @param   aIgnoreCase tells us whether or not to do caseless compare
+   * @param   aOffset tells us where in this string to start searching.
+   *          Use -1 to search from the end of the string.
+   * @param   aCount tells us how many iterations to make starting at the
+   *          given offset.
+   * @return  offset in string, or kNotFound
+   */
+
+  int32_t RFind(const nsCString& aString, bool aIgnoreCase = false,
+                int32_t aOffset = -1, int32_t aCount = -1) const;
+  int32_t RFind(const char* aCString, bool aIgnoreCase = false,
+                int32_t aOffset = -1, int32_t aCount = -1) const;
+
+#ifdef CharT_is_PRUnichar
+  int32_t RFind(const nsAFlatString& aString, int32_t aOffset = -1,
+                int32_t aCount = -1) const;
+  int32_t RFind(const char16_t* aString, int32_t aOffset = -1,
+                int32_t aCount = -1) const;
+#endif
+
+
+  /**
+   *  Search for given char within this string
+   *
+   *  @param   aChar is the character to search for
+   *  @param   aOffset tells us where in this string to start searching
+   *  @param   aCount tells us how far from the offset we are to search.
+   *           Use -1 to search the whole string.
+   *  @return  offset in string, or kNotFound
+   */
+
+  // int32_t FindChar( char16_t aChar, int32_t aOffset=0, int32_t aCount=-1 ) const;
+  int32_t RFindChar(char16_t aChar, int32_t aOffset = -1,
+                    int32_t aCount = -1) const;
+
+
+  /**
+   * This method searches this string for the first character found in
+   * the given string.
+   *
+   * @param aString contains set of chars to be found
+   * @param aOffset tells us where in this string to start searching
+   *        (counting from left)
+   * @return offset in string, or kNotFound
+   */
+
+  int32_t FindCharInSet(const char* aString, int32_t aOffset = 0) const;
+  int32_t FindCharInSet(const self_type& aString, int32_t aOffset = 0) const
+  {
+    return FindCharInSet(aString.get(), aOffset);
+  }
+
+#ifdef CharT_is_PRUnichar
+  int32_t FindCharInSet(const char16_t* aString, int32_t aOffset = 0) const;
+#endif
+
+
+  /**
+   * This method searches this string for the last character found in
+   * the given string.
+   *
+   * @param aString contains set of chars to be found
+   * @param aOffset tells us where in this string to start searching
+   *        (counting from left)
+   * @return offset in string, or kNotFound
+   */
+
+  int32_t RFindCharInSet(const char_type* aString, int32_t aOffset = -1) const;
+  int32_t RFindCharInSet(const self_type& aString, int32_t aOffset = -1) const
+  {
+    return RFindCharInSet(aString.get(), aOffset);
+  }
+
+
+  /**
+   * Compares a given string to this string.
+   *
+   * @param   aString is the string to be compared
+   * @param   aIgnoreCase tells us how to treat case
+   * @param   aCount tells us how many chars to compare
+   * @return  -1,0,1
+   */
+
+#ifdef CharT_is_char
+  int32_t Compare(const char* aString, bool aIgnoreCase = false,
+                  int32_t aCount = -1) const;
+#endif
+
+
+  /**
+   * Equality check between given string and this string.
+   *
+   * @param   aString is the string to check
+   * @param   aIgnoreCase tells us how to treat case
+   * @param   aCount tells us how many chars to compare
+   * @return  boolean
+   */
+#ifdef CharT_is_char
+  bool EqualsIgnoreCase(const char* aString, int32_t aCount = -1) const
+  {
+    return Compare(aString, true, aCount) == 0;
+  }
+#else
+  bool EqualsIgnoreCase(const char* aString, int32_t aCount = -1) const;
+
+
+#endif // !CharT_is_PRUnichar
+
+  /**
+   * Perform string to double-precision float conversion.
+   *
+   * @param   aErrorCode will contain error if one occurs
+   * @return  double-precision float rep of string value
+   */
+  double ToDouble(nsresult* aErrorCode) const;
+
+  /**
+   * Perform string to single-precision float conversion.
+   *
+   * @param   aErrorCode will contain error if one occurs
+   * @return  single-precision float rep of string value
+   */
+  float ToFloat(nsresult* aErrorCode) const
+  {
+    return (float)ToDouble(aErrorCode);
+  }
+
+
+  /**
+   * Perform string to int conversion.
+   * @param   aErrorCode will contain error if one occurs
+   * @param   aRadix tells us which radix to assume; kAutoDetect tells us to determine the radix for you.
+   * @return  int rep of string value, and possible (out) error code
+   */
+  int32_t ToInteger(nsresult* aErrorCode, uint32_t aRadix = kRadix10) const;
+
+  /**
+   * Perform string to 64-bit int conversion.
+   * @param   aErrorCode will contain error if one occurs
+   * @param   aRadix tells us which radix to assume; kAutoDetect tells us to determine the radix for you.
+   * @return  64-bit int rep of string value, and possible (out) error code
+   */
+  int64_t ToInteger64(nsresult* aErrorCode, uint32_t aRadix = kRadix10) const;
+
+
+  /**
+   * |Left|, |Mid|, and |Right| are annoying signatures that seem better almost
+   * any _other_ way than they are now.  Consider these alternatives
+   *
+   * aWritable = aReadable.Left(17);   // ...a member function that returns a |Substring|
+   * aWritable = Left(aReadable, 17);  // ...a global function that returns a |Substring|
+   * Left(aReadable, 17, aWritable);   // ...a global function that does the assignment
+   *
+   * as opposed to the current signature
+   *
+   * aReadable.Left(aWritable, 17);    // ...a member function that does the assignment
+   *
+   * or maybe just stamping them out in favor of |Substring|, they are just duplicate functionality
+   *
+   * aWritable = Substring(aReadable, 0, 17);
+   */
+
+  size_type Mid(self_type& aResult, uint32_t aStartPos, uint32_t aCount) const;
+
+  size_type Left(self_type& aResult, size_type aCount) const
+  {
+    return Mid(aResult, 0, aCount);
+  }
+
+  size_type Right(self_type& aResult, size_type aCount) const
+  {
+    aCount = XPCOM_MIN(mLength, aCount);
+    return Mid(aResult, mLength - aCount, aCount);
+  }
+
+
+  /**
+   * Set a char inside this string at given index
+   *
+   * @param aChar is the char you want to write into this string
+   * @param anIndex is the ofs where you want to write the given char
+   * @return TRUE if successful
+   */
+
+  bool SetCharAt(char16_t aChar, uint32_t aIndex);
+
+
+  /**
+   *  These methods are used to remove all occurrences of the
+   *  characters found in aSet from this string.
+   *
+   *  @param  aSet -- characters to be cut from this
+   */
+  void StripChars(const char* aSet);
+  bool StripChars(const char* aSet, const fallible_t&);
+
+
+  /**
+   *  This method strips whitespace throughout the string.
+   */
+  void StripWhitespace();
+  bool StripWhitespace(const fallible_t&);
+
+
+  /**
+   *  swaps occurence of 1 string for another
+   */
+
+  void ReplaceChar(char_type aOldChar, char_type aNewChar);
+  void ReplaceChar(const char* aSet, char_type aNewChar);
+#ifdef CharT_is_PRUnichar
+  void ReplaceChar(const char16_t* aSet, char16_t aNewChar);
+#endif
+  /**
+   * Replace all occurrences of aTarget with aNewValue.
+   * The complexity of this function is O(n+m), n being the length of the string
+   * and m being the length of aNewValue.
+   */
+  void ReplaceSubstring(const self_type& aTarget, const self_type& aNewValue);
+  void ReplaceSubstring(const char_type* aTarget, const char_type* aNewValue);
+  MOZ_MUST_USE bool ReplaceSubstring(const self_type& aTarget,
+                                     const self_type& aNewValue,
+                                     const fallible_t&);
+  MOZ_MUST_USE bool ReplaceSubstring(const char_type* aTarget,
+                                     const char_type* aNewValue,
+                                     const fallible_t&);
+
+
+  /**
+   *  This method trims characters found in aTrimSet from
+   *  either end of the underlying string.
+   *
+   *  @param   aSet -- contains chars to be trimmed from both ends
+   *  @param   aEliminateLeading
+   *  @param   aEliminateTrailing
+   *  @param   aIgnoreQuotes -- if true, causes surrounding quotes to be ignored
+   *  @return  this
+   */
+  void Trim(const char* aSet, bool aEliminateLeading = true,
+            bool aEliminateTrailing = true, bool aIgnoreQuotes = false);
+
+  /**
+   *  This method strips whitespace from string.
+   *  You can control whether whitespace is yanked from start and end of
+   *  string as well.
+   *
+   *  @param   aEliminateLeading controls stripping of leading ws
+   *  @param   aEliminateTrailing controls stripping of trailing ws
+   */
+  void CompressWhitespace(bool aEliminateLeading = true,
+                          bool aEliminateTrailing = true);
+
+
+  /**
+   * assign/append/insert with _LOSSY_ conversion
+   */
+
+  void AssignWithConversion(const nsTAString_IncompatibleCharT& aString);
+  void AssignWithConversion(const incompatible_char_type* aData,
+                            int32_t aLength = -1);
+
+#endif // !MOZ_STRING_WITH_OBSOLETE_API
+
+  /**
+   * Allow this string to be bound to a character buffer
+   * until the string is rebound or mutated; the caller
+   * must ensure that the buffer outlives the string.
+   */
+  void Rebind(const char_type* aData, size_type aLength);
+
+  /**
+   * verify restrictions for dependent strings
+   */
+  void AssertValidDependentString()
+  {
+    NS_ASSERTION(mData, "nsTDependentString must wrap a non-NULL buffer");
+    NS_ASSERTION(mLength != size_type(-1), "nsTDependentString has bogus length");
+    NS_ASSERTION(mData[mLength] == 0,
+                 "nsTDependentString must wrap only null-terminated strings. "
+                 "You are probably looking for nsTDependentSubstring.");
+  }
+
+
+protected:
+
+  explicit
+  nsTString_CharT(uint32_t aFlags)
+    : substring_type(aFlags)
+  {
+  }
+
+  // allow subclasses to initialize fields directly
+  nsTString_CharT(char_type* aData, size_type aLength, uint32_t aFlags)
+    : substring_type(aData, aLength, aFlags)
+  {
+  }
+
+  struct Segment {
+    uint32_t mBegin, mLength;
+    Segment(uint32_t aBegin, uint32_t aLength)
+      : mBegin(aBegin)
+      , mLength(aLength)
+    {}
+  };
+};
+
+
+class nsTFixedString_CharT : public nsTString_CharT
+{
+public:
+
+  typedef nsTFixedString_CharT self_type;
+  typedef nsTFixedString_CharT fixed_string_type;
+
+public:
+
+  /**
+   * @param aData
+   *        fixed-size buffer to be used by the string (the contents of
+   *        this buffer may be modified by the string)
+   * @param aStorageSize
+   *        the size of the fixed buffer
+   * @param aLength (optional)
+   *        the length of the string already contained in the buffer
+   */
+
+  nsTFixedString_CharT(char_type* aData, size_type aStorageSize)
+    : string_type(aData, uint32_t(char_traits::length(aData)),
+                  F_TERMINATED | F_FIXED | F_CLASS_FIXED)
+    , mFixedCapacity(aStorageSize - 1)
+    , mFixedBuf(aData)
+  {
+  }
+
+  nsTFixedString_CharT(char_type* aData, size_type aStorageSize,
+                       size_type aLength)
+    : string_type(aData, aLength, F_TERMINATED | F_FIXED | F_CLASS_FIXED)
+    , mFixedCapacity(aStorageSize - 1)
+    , mFixedBuf(aData)
+  {
+    // null-terminate
+    mFixedBuf[aLength] = char_type(0);
+  }
+
+  // |operator=| does not inherit, so we must define our own
+  self_type& operator=(char_type aChar)
+  {
+    Assign(aChar);
+    return *this;
+  }
+  self_type& operator=(const char_type* aData)
+  {
+    Assign(aData);
+    return *this;
+  }
+  self_type& operator=(const substring_type& aStr)
+  {
+    Assign(aStr);
+    return *this;
+  }
+  self_type& operator=(const substring_tuple_type& aTuple)
+  {
+    Assign(aTuple);
+    return *this;
+  }
+
+protected:
+
+  friend class nsTSubstring_CharT;
+
+  size_type  mFixedCapacity;
+  char_type* mFixedBuf;
+};
+
+
+/**
+ * nsTAutoString_CharT
+ *
+ * Subclass of nsTString_CharT that adds support for stack-based string
+ * allocation.  It is normally not a good idea to use this class on the
+ * heap, because it will allocate space which may be wasted if the string
+ * it contains is significantly smaller or any larger than 64 characters.
+ *
+ * NAMES:
+ *   nsAutoString for wide characters
+ *   nsAutoCString for narrow characters
+ */
+class MOZ_NON_MEMMOVABLE nsTAutoString_CharT : public nsTFixedString_CharT
+{
+public:
+
+  typedef nsTAutoString_CharT self_type;
+
+public:
+
+  /**
+   * constructors
+   */
+
+  nsTAutoString_CharT()
+    : fixed_string_type(mStorage, kDefaultStorageSize, 0)
+  {
+  }
+
+  explicit
+  nsTAutoString_CharT(char_type aChar)
+    : fixed_string_type(mStorage, kDefaultStorageSize, 0)
+  {
+    Assign(aChar);
+  }
+
+  explicit
+  nsTAutoString_CharT(const char_type* aData, size_type aLength = size_type(-1))
+    : fixed_string_type(mStorage, kDefaultStorageSize, 0)
+  {
+    Assign(aData, aLength);
+  }
+
+#if defined(CharT_is_PRUnichar) && defined(MOZ_USE_CHAR16_WRAPPER)
+  explicit
+  nsTAutoString_CharT(char16ptr_t aData, size_type aLength = size_type(-1))
+    : nsTAutoString_CharT(static_cast<const char16_t*>(aData), aLength)
+  {
+  }
+#endif
+
+  nsTAutoString_CharT(const self_type& aStr)
+    : fixed_string_type(mStorage, kDefaultStorageSize, 0)
+  {
+    Assign(aStr);
+  }
+
+  explicit
+  nsTAutoString_CharT(const substring_type& aStr)
+    : fixed_string_type(mStorage, kDefaultStorageSize, 0)
+  {
+    Assign(aStr);
+  }
+
+  MOZ_IMPLICIT nsTAutoString_CharT(const substring_tuple_type& aTuple)
+    : fixed_string_type(mStorage, kDefaultStorageSize, 0)
+  {
+    Assign(aTuple);
+  }
+
+  // |operator=| does not inherit, so we must define our own
+  self_type& operator=(char_type aChar)
+  {
+    Assign(aChar);
+    return *this;
+  }
+  self_type& operator=(const char_type* aData)
+  {
+    Assign(aData);
+    return *this;
+  }
+#if defined(CharT_is_PRUnichar) && defined(MOZ_USE_CHAR16_WRAPPER)
+  self_type& operator=(char16ptr_t aStr)
+  {
+    Assign(aStr);
+    return *this;
+  }
+#endif
+  self_type& operator=(const self_type& aStr)
+  {
+    Assign(aStr);
+    return *this;
+  }
+  self_type& operator=(const substring_type& aStr)
+  {
+    Assign(aStr);
+    return *this;
+  }
+  self_type& operator=(const substring_tuple_type& aTuple)
+  {
+    Assign(aTuple);
+    return *this;
+  }
+
+  enum
+  {
+    kDefaultStorageSize = 64
+  };
+
+private:
+
+  char_type mStorage[kDefaultStorageSize];
+};
+
+
+//
+// nsAutoString stores pointers into itself which are invalidated when an
+// nsTArray is resized, so nsTArray must not be instantiated with nsAutoString
+// elements!
+//
+template<class E> class nsTArrayElementTraits;
+template<>
+class nsTArrayElementTraits<nsTAutoString_CharT>
+{
+public:
+  template<class A> struct Dont_Instantiate_nsTArray_of;
+  template<class A> struct Instead_Use_nsTArray_of;
+
+  static Dont_Instantiate_nsTArray_of<nsTAutoString_CharT>*
+  Construct(Instead_Use_nsTArray_of<nsTString_CharT>* aE)
+  {
+    return 0;
+  }
+  template<class A>
+  static Dont_Instantiate_nsTArray_of<nsTAutoString_CharT>*
+  Construct(Instead_Use_nsTArray_of<nsTString_CharT>* aE, const A& aArg)
+  {
+    return 0;
+  }
+  static Dont_Instantiate_nsTArray_of<nsTAutoString_CharT>*
+  Destruct(Instead_Use_nsTArray_of<nsTString_CharT>* aE)
+  {
+    return 0;
+  }
+};
+
+/**
+ * nsTXPIDLString extends nsTString such that:
+ *
+ *   (1) mData can be null
+ *   (2) objects of this type can be automatically cast to |const CharT*|
+ *   (3) getter_Copies method is supported to adopt data allocated with
+ *       moz_xmalloc, such as "out string" parameters in XPIDL.
+ *
+ * NAMES:
+ *   nsXPIDLString for wide characters
+ *   nsXPIDLCString for narrow characters
+ */
+class nsTXPIDLString_CharT : public nsTString_CharT
+{
+public:
+
+  typedef nsTXPIDLString_CharT self_type;
+
+public:
+
+  nsTXPIDLString_CharT()
+    : string_type(char_traits::sEmptyBuffer, 0, F_TERMINATED | F_VOIDED)
+  {
+  }
+
+  // copy-constructor required to avoid default
+  nsTXPIDLString_CharT(const self_type& aStr)
+    : string_type(char_traits::sEmptyBuffer, 0, F_TERMINATED | F_VOIDED)
+  {
+    Assign(aStr);
+  }
+
+  // return nullptr if we are voided
+#if defined(CharT_is_PRUnichar) && defined(MOZ_USE_CHAR16_WRAPPER)
+  char16ptr_t get() const
+#else
+  const char_type* get() const
+#endif
+  {
+    return (mFlags & F_VOIDED) ? nullptr : mData;
+  }
+
+  // this case operator is the reason why this class cannot just be a
+  // typedef for nsTString
+  operator const char_type*() const
+  {
+    return get();
+  }
+
+  // need this to diambiguous operator[int]
+  char_type operator[](int32_t aIndex) const
+  {
+    return CharAt(index_type(aIndex));
+  }
+
+  // |operator=| does not inherit, so we must define our own
+  self_type& operator=(char_type aChar)
+  {
+    Assign(aChar);
+    return *this;
+  }
+  self_type& operator=(const char_type* aStr)
+  {
+    Assign(aStr);
+    return *this;
+  }
+  self_type& operator=(const self_type& aStr)
+  {
+    Assign(aStr);
+    return *this;
+  }
+  self_type& operator=(const substring_type& aStr)
+  {
+    Assign(aStr);
+    return *this;
+  }
+  self_type& operator=(const substring_tuple_type& aTuple)
+  {
+    Assign(aTuple);
+    return *this;
+  }
+};
+
+
+/**
+ * getter_Copies support for use with raw string out params:
+ *
+ *    NS_IMETHOD GetBlah(char**);
+ *
+ *    void some_function()
+ *    {
+ *      nsXPIDLCString blah;
+ *      GetBlah(getter_Copies(blah));
+ *      // ...
+ *    }
+ */
+class MOZ_STACK_CLASS nsTGetterCopies_CharT
+{
+public:
+  typedef CharT char_type;
+
+  explicit nsTGetterCopies_CharT(nsTSubstring_CharT& aStr)
+    : mString(aStr)
+    , mData(nullptr)
+  {
+  }
+
+  ~nsTGetterCopies_CharT()
+  {
+    mString.Adopt(mData); // OK if mData is null
+  }
+
+  operator char_type**()
+  {
+    return &mData;
+  }
+
+private:
+  nsTSubstring_CharT& mString;
+  char_type* mData;
+};
+
+inline nsTGetterCopies_CharT
+getter_Copies(nsTSubstring_CharT& aString)
+{
+  return nsTGetterCopies_CharT(aString);
+}
+
+
+/**
+ * nsTAdoptingString extends nsTXPIDLString such that:
+ *
+ * (1) Adopt given string on construction or assignment, i.e. take
+ * the value of what's given, and make what's given forget its
+ * value. Note that this class violates constness in a few
+ * places. Be careful!
+ */
+class nsTAdoptingString_CharT : public nsTXPIDLString_CharT
+{
+public:
+
+  typedef nsTAdoptingString_CharT self_type;
+
+public:
+
+  explicit nsTAdoptingString_CharT()
+  {
+  }
+  explicit nsTAdoptingString_CharT(char_type* aStr,
+                                   size_type aLength = size_type(-1))
+  {
+    Adopt(aStr, aLength);
+  }
+
+  // copy-constructor required to adopt on copy. Note that this
+  // will violate the constness of |aStr| in the operator=()
+  // call. |aStr| will be truncated as a side-effect of this
+  // constructor.
+  nsTAdoptingString_CharT(const self_type& aStr)
+  {
+    *this = aStr;
+  }
+
+  // |operator=| does not inherit, so we must define our own
+  self_type& operator=(const substring_type& aStr)
+  {
+    Assign(aStr);
+    return *this;
+  }
+  self_type& operator=(const substring_tuple_type& aTuple)
+  {
+    Assign(aTuple);
+    return *this;
+  }
+
+  // Adopt(), if possible, when assigning to a self_type&. Note
+  // that this violates the constness of aStr, aStr is always
+  // truncated when this operator is called.
+  self_type& operator=(const self_type& aStr);
+
+private:
+  self_type& operator=(const char_type* aData) = delete;
+  self_type& operator=(char_type* aData) = delete;
+};
+
diff --git a/xpcom/string/nsTStringComparator.cpp b/xpcom/string/nsTStringComparator.cpp
new file mode 100644
index 000000000..3f383c65f
--- /dev/null
+++ b/xpcom/string/nsTStringComparator.cpp
@@ -0,0 +1,50 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+int NS_FASTCALL
+Compare(const nsTSubstring_CharT::base_string_type& aLhs,
+        const nsTSubstring_CharT::base_string_type& aRhs,
+        const nsTStringComparator_CharT& comp)
+{
+  typedef nsTSubstring_CharT::size_type size_type;
+
+  if (&aLhs == &aRhs) {
+    return 0;
+  }
+
+  nsTSubstring_CharT::const_iterator leftIter, rightIter;
+  aLhs.BeginReading(leftIter);
+  aRhs.BeginReading(rightIter);
+
+  size_type lLength = aLhs.Length();
+  size_type rLength = aRhs.Length();
+  size_type lengthToCompare = XPCOM_MIN(lLength, rLength);
+
+  int result;
+  if ((result = comp(leftIter.get(), rightIter.get(),
+                     lengthToCompare, lengthToCompare)) == 0) {
+    if (lLength < rLength) {
+      result = -1;
+    } else if (rLength < lLength) {
+      result = 1;
+    } else {
+      result = 0;
+    }
+  }
+
+  return result;
+}
+
+int
+nsTDefaultStringComparator_CharT::operator()(const char_type* aLhs,
+                                             const char_type* aRhs,
+                                             uint32_t aLLength,
+                                             uint32_t aRLength) const
+{
+  return
+    aLLength == aRLength ? nsCharTraits<CharT>::compare(aLhs, aRhs, aLLength) :
+                            (aLLength > aRLength) ? 1 : -1;
+}
diff --git a/xpcom/string/nsTStringObsolete.cpp b/xpcom/string/nsTStringObsolete.cpp
new file mode 100644
index 000000000..5a47ca310
--- /dev/null
+++ b/xpcom/string/nsTStringObsolete.cpp
@@ -0,0 +1,700 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsTArray.h"
+
+/**
+ * nsTString::Find
+ *
+ * aOffset specifies starting index
+ * aCount specifies number of string compares (iterations)
+ */
+
+int32_t
+nsTString_CharT::Find( const nsCString& aString, bool aIgnoreCase, int32_t aOffset, int32_t aCount) const
+{
+  // this method changes the meaning of aOffset and aCount:
+  Find_ComputeSearchRange(mLength, aString.Length(), aOffset, aCount);
+
+  int32_t result = FindSubstring(mData + aOffset, aCount, aString.get(), aString.Length(), aIgnoreCase);
+  if (result != kNotFound)
+    result += aOffset;
+  return result;
+}
+
+int32_t
+nsTString_CharT::Find( const char* aString, bool aIgnoreCase, int32_t aOffset, int32_t aCount) const
+{
+  return Find(nsDependentCString(aString), aIgnoreCase, aOffset, aCount);
+}
+
+
+/**
+ * nsTString::RFind
+ *
+ * aOffset specifies starting index
+ * aCount specifies number of string compares (iterations)
+ */
+
+int32_t
+nsTString_CharT::RFind( const nsCString& aString, bool aIgnoreCase, int32_t aOffset, int32_t aCount) const
+{
+  // this method changes the meaning of aOffset and aCount:
+  RFind_ComputeSearchRange(mLength, aString.Length(), aOffset, aCount);
+
+  int32_t result = RFindSubstring(mData + aOffset, aCount, aString.get(), aString.Length(), aIgnoreCase);
+  if (result != kNotFound)
+    result += aOffset;
+  return result;
+}
+
+int32_t
+nsTString_CharT::RFind( const char* aString, bool aIgnoreCase, int32_t aOffset, int32_t aCount) const
+{
+  return RFind(nsDependentCString(aString), aIgnoreCase, aOffset, aCount);
+}
+
+
+/**
+ * nsTString::RFindChar
+ */
+
+int32_t
+nsTString_CharT::RFindChar( char16_t aChar, int32_t aOffset, int32_t aCount) const
+{
+  return nsBufferRoutines<CharT>::rfind_char(mData, mLength, aOffset, aChar, aCount);
+}
+
+
+/**
+ * nsTString::FindCharInSet
+ */
+
+int32_t
+nsTString_CharT::FindCharInSet( const char* aSet, int32_t aOffset ) const
+{
+  if (aOffset < 0)
+    aOffset = 0;
+  else if (aOffset >= int32_t(mLength))
+    return kNotFound;
+
+  int32_t result = ::FindCharInSet(mData + aOffset, mLength - aOffset, aSet);
+  if (result != kNotFound)
+    result += aOffset;
+  return result;
+}
+
+
+/**
+ * nsTString::RFindCharInSet
+ */
+
+int32_t
+nsTString_CharT::RFindCharInSet( const CharT* aSet, int32_t aOffset ) const
+{
+  // We want to pass a "data length" to ::RFindCharInSet
+  if (aOffset < 0 || aOffset > int32_t(mLength))
+    aOffset = mLength;
+  else
+    ++aOffset;
+
+  return ::RFindCharInSet(mData, aOffset, aSet);
+}
+
+
+// it's a shame to replicate this code.  it was done this way in the past
+// to help performance.  this function also gets to keep the rickg style
+// indentation :-/
+int32_t
+nsTString_CharT::ToInteger( nsresult* aErrorCode, uint32_t aRadix ) const
+{
+  CharT*  cp=mData;
+  int32_t theRadix=10; // base 10 unless base 16 detected, or overriden (aRadix != kAutoDetect)
+  int32_t result=0;
+  bool    negate=false;
+  CharT   theChar=0;
+
+  //initial value, override if we find an integer
+  *aErrorCode=NS_ERROR_ILLEGAL_VALUE;
+
+  if(cp) {
+
+    //begin by skipping over leading chars that shouldn't be part of the number...
+
+    CharT*  endcp=cp+mLength;
+    bool    done=false;
+
+    while((cp<endcp) && (!done)){
+      switch(*cp++) {
+        case 'a': case 'b': case 'c': case 'd': case 'e': case 'f':
+        case 'A': case 'B': case 'C': case 'D': case 'E': case 'F':
+          theRadix=16;
+          done=true;
+          break;
+        case '0': case '1': case '2': case '3': case '4':
+        case '5': case '6': case '7': case '8': case '9':
+          done=true;
+          break;
+        case '-':
+          negate=true; //fall through...
+          break;
+        case 'X': case 'x':
+          theRadix=16;
+          break;
+        default:
+          break;
+      } //switch
+    }
+
+    if (done) {
+
+      //integer found
+      *aErrorCode = NS_OK;
+
+      if (aRadix!=kAutoDetect) theRadix = aRadix; // override
+
+      //now iterate the numeric chars and build our result
+      CharT* first=--cp;  //in case we have to back up.
+      bool haveValue = false;
+
+      while(cp<endcp){
+        int32_t oldresult = result;
+
+        theChar=*cp++;
+        if(('0'<=theChar) && (theChar<='9')){
+          result = (theRadix * result) + (theChar-'0');
+          haveValue = true;
+        }
+        else if((theChar>='A') && (theChar<='F')) {
+          if(10==theRadix) {
+            if(kAutoDetect==aRadix){
+              theRadix=16;
+              cp=first; //backup
+              result=0;
+              haveValue = false;
+            }
+            else {
+              *aErrorCode=NS_ERROR_ILLEGAL_VALUE;
+              result=0;
+              break;
+            }
+          }
+          else {
+            result = (theRadix * result) + ((theChar-'A')+10);
+            haveValue = true;
+          }
+        }
+        else if((theChar>='a') && (theChar<='f')) {
+          if(10==theRadix) {
+            if(kAutoDetect==aRadix){
+              theRadix=16;
+              cp=first; //backup
+              result=0;
+              haveValue = false;
+            }
+            else {
+              *aErrorCode=NS_ERROR_ILLEGAL_VALUE;
+              result=0;
+              break;
+            }
+          }
+          else {
+            result = (theRadix * result) + ((theChar-'a')+10);
+            haveValue = true;
+          }
+        }
+        else if((('X'==theChar) || ('x'==theChar)) && (!haveValue || result == 0)) {
+          continue;
+        }
+        else if((('#'==theChar) || ('+'==theChar)) && !haveValue) {
+          continue;
+        }
+        else {
+          //we've encountered a char that's not a legal number or sign
+          break;
+        }
+
+        if (result < oldresult) {
+          // overflow!
+          *aErrorCode = NS_ERROR_ILLEGAL_VALUE;
+          result = 0;
+          break;
+        }
+      } //while
+      if(negate)
+        result=-result;
+    } //if
+  }
+  return result;
+}
+
+
+/**
+ * nsTString::ToInteger64
+ */
+int64_t
+nsTString_CharT::ToInteger64( nsresult* aErrorCode, uint32_t aRadix ) const
+{
+  CharT*  cp=mData;
+  int32_t theRadix=10; // base 10 unless base 16 detected, or overriden (aRadix != kAutoDetect)
+  int64_t result=0;
+  bool    negate=false;
+  CharT   theChar=0;
+
+  //initial value, override if we find an integer
+  *aErrorCode=NS_ERROR_ILLEGAL_VALUE;
+
+  if(cp) {
+
+    //begin by skipping over leading chars that shouldn't be part of the number...
+
+    CharT*  endcp=cp+mLength;
+    bool    done=false;
+
+    while((cp<endcp) && (!done)){
+      switch(*cp++) {
+        case 'a': case 'b': case 'c': case 'd': case 'e': case 'f':
+        case 'A': case 'B': case 'C': case 'D': case 'E': case 'F':
+          theRadix=16;
+          done=true;
+          break;
+        case '0': case '1': case '2': case '3': case '4':
+        case '5': case '6': case '7': case '8': case '9':
+          done=true;
+          break;
+        case '-':
+          negate=true; //fall through...
+          break;
+        case 'X': case 'x':
+          theRadix=16;
+          break;
+        default:
+          break;
+      } //switch
+    }
+
+    if (done) {
+
+      //integer found
+      *aErrorCode = NS_OK;
+
+      if (aRadix!=kAutoDetect) theRadix = aRadix; // override
+
+      //now iterate the numeric chars and build our result
+      CharT* first=--cp;  //in case we have to back up.
+      bool haveValue = false;
+
+      while(cp<endcp){
+        int64_t oldresult = result;
+
+        theChar=*cp++;
+        if(('0'<=theChar) && (theChar<='9')){
+          result = (theRadix * result) + (theChar-'0');
+          haveValue = true;
+        }
+        else if((theChar>='A') && (theChar<='F')) {
+          if(10==theRadix) {
+            if(kAutoDetect==aRadix){
+              theRadix=16;
+              cp=first; //backup
+              result=0;
+              haveValue = false;
+            }
+            else {
+              *aErrorCode=NS_ERROR_ILLEGAL_VALUE;
+              result=0;
+              break;
+            }
+          }
+          else {
+            result = (theRadix * result) + ((theChar-'A')+10);
+            haveValue = true;
+          }
+        }
+        else if((theChar>='a') && (theChar<='f')) {
+          if(10==theRadix) {
+            if(kAutoDetect==aRadix){
+              theRadix=16;
+              cp=first; //backup
+              result=0;
+              haveValue = false;
+            }
+            else {
+              *aErrorCode=NS_ERROR_ILLEGAL_VALUE;
+              result=0;
+              break;
+            }
+          }
+          else {
+            result = (theRadix * result) + ((theChar-'a')+10);
+            haveValue = true;
+          }
+        }
+        else if((('X'==theChar) || ('x'==theChar)) && (!haveValue || result == 0)) {
+          continue;
+        }
+        else if((('#'==theChar) || ('+'==theChar)) && !haveValue) {
+          continue;
+        }
+        else {
+          //we've encountered a char that's not a legal number or sign
+          break;
+        }
+
+        if (result < oldresult) {
+          // overflow!
+          *aErrorCode = NS_ERROR_ILLEGAL_VALUE;
+          result = 0;
+          break;
+        }
+      } //while
+      if(negate)
+        result=-result;
+    } //if
+  }
+  return result;
+}
+
+
+/**
+   * nsTString::Mid
+   */
+
+uint32_t
+nsTString_CharT::Mid( self_type& aResult, index_type aStartPos, size_type aLengthToCopy ) const
+{
+  if (aStartPos == 0 && aLengthToCopy >= mLength)
+    aResult = *this;
+  else
+    aResult = Substring(*this, aStartPos, aLengthToCopy);
+
+  return aResult.mLength;
+}
+
+
+/**
+ * nsTString::SetCharAt
+ */
+
+bool
+nsTString_CharT::SetCharAt( char16_t aChar, uint32_t aIndex )
+{
+  if (aIndex >= mLength)
+    return false;
+
+  if (!EnsureMutable())
+    AllocFailed(mLength);
+
+  mData[aIndex] = CharT(aChar);
+  return true;
+}
+
+
+/**
+ * nsTString::StripChars,StripChar,StripWhitespace
+ */
+
+void
+nsTString_CharT::StripChars( const char* aSet )
+{
+  if (!EnsureMutable())
+    AllocFailed(mLength);
+
+  mLength = nsBufferRoutines<CharT>::strip_chars(mData, mLength, aSet);
+}
+
+bool
+nsTString_CharT::StripChars( const char* aSet, const fallible_t& )
+{
+  if (!EnsureMutable()) {
+    return false;
+  }
+
+  mLength = nsBufferRoutines<CharT>::strip_chars(mData, mLength, aSet);
+  return true;
+}
+
+void
+nsTString_CharT::StripWhitespace()
+{
+  StripChars(kWhitespace);
+}
+
+bool
+nsTString_CharT::StripWhitespace(const fallible_t& aFallible)
+{
+  return StripChars(kWhitespace, aFallible);
+}
+
+/**
+ * nsTString::ReplaceChar,ReplaceSubstring
+ */
+
+void
+nsTString_CharT::ReplaceChar( char_type aOldChar, char_type aNewChar )
+{
+  if (!EnsureMutable()) // XXX do this lazily?
+    AllocFailed(mLength);
+
+  for (uint32_t i=0; i<mLength; ++i)
+  {
+    if (mData[i] == aOldChar)
+      mData[i] = aNewChar;
+  }
+}
+
+void
+nsTString_CharT::ReplaceChar( const char* aSet, char_type aNewChar )
+{
+  if (!EnsureMutable()) // XXX do this lazily?
+    AllocFailed(mLength);
+
+  char_type* data = mData;
+  uint32_t lenRemaining = mLength;
+
+  while (lenRemaining)
+  {
+    int32_t i = ::FindCharInSet(data, lenRemaining, aSet);
+    if (i == kNotFound)
+      break;
+
+    data[i++] = aNewChar;
+    data += i;
+    lenRemaining -= i;
+  }
+}
+
+void ReleaseData(void* aData, uint32_t aFlags);
+
+void
+nsTString_CharT::ReplaceSubstring(const char_type* aTarget,
+                                  const char_type* aNewValue)
+{
+  ReplaceSubstring(nsTDependentString_CharT(aTarget),
+                   nsTDependentString_CharT(aNewValue));
+}
+
+bool
+nsTString_CharT::ReplaceSubstring(const char_type* aTarget,
+                                  const char_type* aNewValue,
+                                  const fallible_t& aFallible)
+{
+  return ReplaceSubstring(nsTDependentString_CharT(aTarget),
+                          nsTDependentString_CharT(aNewValue),
+                          aFallible);
+}
+
+void
+nsTString_CharT::ReplaceSubstring(const self_type& aTarget,
+                                  const self_type& aNewValue)
+{
+  if (!ReplaceSubstring(aTarget, aNewValue, mozilla::fallible)) {
+    // Note that this may wildly underestimate the allocation that failed, as
+    // we could have been replacing multiple copies of aTarget.
+    AllocFailed(mLength + (aNewValue.Length() - aTarget.Length()));
+  }
+}
+
+bool
+nsTString_CharT::ReplaceSubstring(const self_type& aTarget,
+                                  const self_type& aNewValue,
+                                  const fallible_t&)
+{
+  if (aTarget.Length() == 0)
+    return true;
+
+  // Remember all of the non-matching parts.
+  AutoTArray<Segment, 16> nonMatching;
+  uint32_t i = 0;
+  uint32_t newLength = 0;
+  while (true)
+  {
+    int32_t r = FindSubstring(mData + i, mLength - i, static_cast<const char_type*>(aTarget.Data()), aTarget.Length(), false);
+    int32_t until = (r == kNotFound) ? mLength - i : r;
+    nonMatching.AppendElement(Segment(i, until));
+    newLength += until;
+    if (r == kNotFound) {
+      break;
+    }
+
+    newLength += aNewValue.Length();
+    i += r + aTarget.Length();
+    if (i >= mLength) {
+      // Add an auxiliary entry at the end of the list to help as an edge case
+      // for the algorithms below.
+      nonMatching.AppendElement(Segment(mLength, 0));
+      break;
+    }
+  }
+
+  // If there's only one non-matching segment, then the target string was not
+  // found, and there's nothing to do.
+  if (nonMatching.Length() == 1) {
+    MOZ_ASSERT(nonMatching[0].mBegin == 0 && nonMatching[0].mLength == mLength,
+               "We should have the correct non-matching segment.");
+    return true;
+  }
+
+  // Make sure that we can mutate our buffer.
+  // Note that we always allocate at least an mLength sized buffer, because the
+  // rest of the algorithm relies on having access to all of the original
+  // string.  In other words, we over-allocate in the shrinking case.
+  char_type* oldData;
+  uint32_t oldFlags;
+  if (!MutatePrep(XPCOM_MAX(mLength, newLength), &oldData, &oldFlags))
+    return false;
+  if (oldData) {
+    // Copy all of the old data to the new buffer.
+    char_traits::copy(mData, oldData, mLength);
+    ::ReleaseData(oldData, oldFlags);
+  }
+
+  if (aTarget.Length() >= aNewValue.Length()) {
+    // In the shrinking case, start filling the buffer from the beginning.
+    const uint32_t delta = (aTarget.Length() - aNewValue.Length());
+    for (i = 1; i < nonMatching.Length(); ++i) {
+      // When we move the i'th non-matching segment into position, we need to
+      // account for the characters deleted by the previous |i| replacements by
+      // subtracting |i * delta|.
+      const char_type* sourceSegmentPtr = mData + nonMatching[i].mBegin;
+      char_type* destinationSegmentPtr = mData + nonMatching[i].mBegin - i * delta;
+      // Write the i'th replacement immediately before the new i'th non-matching
+      // segment.
+      char_traits::copy(destinationSegmentPtr - aNewValue.Length(),
+                        aNewValue.Data(), aNewValue.Length());
+      char_traits::move(destinationSegmentPtr, sourceSegmentPtr,
+                        nonMatching[i].mLength);
+    }
+  } else {
+    // In the growing case, start filling the buffer from the end.
+    const uint32_t delta = (aNewValue.Length() - aTarget.Length());
+    for (i = nonMatching.Length() - 1; i > 0; --i) {
+      // When we move the i'th non-matching segment into position, we need to
+      // account for the characters added by the previous |i| replacements by
+      // adding |i * delta|.
+      const char_type* sourceSegmentPtr = mData + nonMatching[i].mBegin;
+      char_type* destinationSegmentPtr = mData + nonMatching[i].mBegin + i * delta;
+      char_traits::move(destinationSegmentPtr, sourceSegmentPtr,
+                        nonMatching[i].mLength);
+      // Write the i'th replacement immediately before the new i'th non-matching
+      // segment.
+      char_traits::copy(destinationSegmentPtr - aNewValue.Length(),
+                        aNewValue.Data(), aNewValue.Length());
+    }
+  }
+
+  // Adjust the length and make sure the string is null terminated.
+  mLength = newLength;
+  mData[mLength] = char_type(0);
+
+  return true;
+}
+
+/**
+ * nsTString::Trim
+ */
+
+void
+nsTString_CharT::Trim( const char* aSet, bool aTrimLeading, bool aTrimTrailing, bool aIgnoreQuotes )
+{
+  // the old implementation worried about aSet being null :-/
+  if (!aSet)
+    return;
+
+  char_type* start = mData;
+  char_type* end   = mData + mLength;
+
+  // skip over quotes if requested
+  if (aIgnoreQuotes && mLength > 2 && mData[0] == mData[mLength - 1] &&
+      (mData[0] == '\'' || mData[0] == '"'))
+  {
+    ++start;
+    --end;
+  }
+
+  uint32_t setLen = nsCharTraits<char>::length(aSet);
+
+  if (aTrimLeading)
+  {
+    uint32_t cutStart = start - mData;
+    uint32_t cutLength = 0;
+
+    // walk forward from start to end
+    for (; start != end; ++start, ++cutLength)
+    {
+      int32_t pos = FindChar1(aSet, setLen, 0, *start, setLen);
+      if (pos == kNotFound)
+        break;
+    }
+
+    if (cutLength)
+    {
+      Cut(cutStart, cutLength);
+
+      // reset iterators
+      start = mData + cutStart;
+      end   = mData + mLength - cutStart;
+    }
+  }
+
+  if (aTrimTrailing)
+  {
+    uint32_t cutEnd = end - mData;
+    uint32_t cutLength = 0;
+
+    // walk backward from end to start
+    --end;
+    for (; end >= start; --end, ++cutLength)
+    {
+      int32_t pos = FindChar1(aSet, setLen, 0, *end, setLen);
+      if (pos == kNotFound)
+        break;
+    }
+
+    if (cutLength)
+      Cut(cutEnd - cutLength, cutLength);
+  }
+}
+
+
+/**
+ * nsTString::CompressWhitespace
+ */
+
+void
+nsTString_CharT::CompressWhitespace( bool aTrimLeading, bool aTrimTrailing )
+{
+  const char* set = kWhitespace;
+
+  ReplaceChar(set, ' ');
+  Trim(set, aTrimLeading, aTrimTrailing);
+
+  // this one does some questionable fu... just copying the old code!
+  mLength = nsBufferRoutines<char_type>::compress_chars(mData, mLength, set);
+}
+
+
+/**
+ * nsTString::AssignWithConversion
+ */
+
+void
+nsTString_CharT::AssignWithConversion( const incompatible_char_type* aData, int32_t aLength )
+{
+  // for compatibility with the old string implementation, we need to allow
+  // for a nullptr input buffer :-(
+  if (!aData)
+  {
+    Truncate();
+  }
+  else
+  {
+    if (aLength < 0)
+      aLength = nsCharTraits<incompatible_char_type>::length(aData);
+
+    AssignWithConversion(Substring(aData, aLength));
+  }
+}
diff --git a/xpcom/string/nsTSubstring.cpp b/xpcom/string/nsTSubstring.cpp
new file mode 100644
index 000000000..a3a830b9d
--- /dev/null
+++ b/xpcom/string/nsTSubstring.cpp
@@ -0,0 +1,1089 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/CheckedInt.h"
+#include "mozilla/double-conversion.h"
+#include "mozilla/MemoryReporting.h"
+
+using double_conversion::DoubleToStringConverter;
+
+const nsTSubstring_CharT::size_type nsTSubstring_CharT::kMaxCapacity =
+    (nsTSubstring_CharT::size_type(-1) /
+        2 - sizeof(nsStringBuffer)) /
+    sizeof(nsTSubstring_CharT::char_type) - 2;
+
+#ifdef XPCOM_STRING_CONSTRUCTOR_OUT_OF_LINE
+nsTSubstring_CharT::nsTSubstring_CharT(char_type* aData, size_type aLength,
+                                       uint32_t aFlags)
+  : mData(aData),
+    mLength(aLength),
+    mFlags(aFlags)
+{
+  MOZ_RELEASE_ASSERT(CheckCapacity(aLength), "String is too large.");
+
+  if (aFlags & F_OWNED) {
+    STRING_STAT_INCREMENT(Adopt);
+    MOZ_LOG_CTOR(mData, "StringAdopt", 1);
+  }
+}
+#endif /* XPCOM_STRING_CONSTRUCTOR_OUT_OF_LINE */
+
+/**
+ * helper function for down-casting a nsTSubstring to a nsTFixedString.
+ */
+inline const nsTFixedString_CharT*
+AsFixedString(const nsTSubstring_CharT* aStr)
+{
+  return static_cast<const nsTFixedString_CharT*>(aStr);
+}
+
+
+/**
+ * this function is called to prepare mData for writing.  the given capacity
+ * indicates the required minimum storage size for mData, in sizeof(char_type)
+ * increments.  this function returns true if the operation succeeds.  it also
+ * returns the old data and old flags members if mData is newly allocated.
+ * the old data must be released by the caller.
+ */
+bool
+nsTSubstring_CharT::MutatePrep(size_type aCapacity, char_type** aOldData,
+                               uint32_t* aOldFlags)
+{
+  // initialize to no old data
+  *aOldData = nullptr;
+  *aOldFlags = 0;
+
+  size_type curCapacity = Capacity();
+
+  // If |aCapacity > kMaxCapacity|, then our doubling algorithm may not be
+  // able to allocate it.  Just bail out in cases like that.  We don't want
+  // to be allocating 2GB+ strings anyway.
+  static_assert((sizeof(nsStringBuffer) & 0x1) == 0,
+                "bad size for nsStringBuffer");
+  if (!CheckCapacity(aCapacity)) {
+      return false;
+  }
+
+  // |curCapacity == 0| means that the buffer is immutable or 0-sized, so we
+  // need to allocate a new buffer. We cannot use the existing buffer even
+  // though it might be large enough.
+
+  if (curCapacity != 0) {
+    if (aCapacity <= curCapacity) {
+      mFlags &= ~F_VOIDED;  // mutation clears voided flag
+      return true;
+    }
+  }
+
+  if (curCapacity < aCapacity) {
+    // We increase our capacity so that the allocated buffer grows
+    // exponentially, which gives us amortized O(1) appending. Below the
+    // threshold, we use powers-of-two. Above the threshold, we grow by at
+    // least 1.125, rounding up to the nearest MiB.
+    const size_type slowGrowthThreshold = 8 * 1024 * 1024;
+
+    // nsStringBuffer allocates sizeof(nsStringBuffer) + passed size, and
+    // storageSize below wants extra 1 * sizeof(char_type).
+    const size_type neededExtraSpace =
+      sizeof(nsStringBuffer) / sizeof(char_type) + 1;
+
+    size_type temp;
+    if (aCapacity >= slowGrowthThreshold) {
+      size_type minNewCapacity = curCapacity + (curCapacity >> 3); // multiply by 1.125
+      temp = XPCOM_MAX(aCapacity, minNewCapacity) + neededExtraSpace;
+
+      // Round up to the next multiple of MiB, but ensure the expected
+      // capacity doesn't include the extra space required by nsStringBuffer
+      // and null-termination.
+      const size_t MiB = 1 << 20;
+      temp = (MiB * ((temp + MiB - 1) / MiB)) - neededExtraSpace;
+    } else {
+      // Round up to the next power of two.
+      temp =
+        mozilla::RoundUpPow2(aCapacity + neededExtraSpace) - neededExtraSpace;
+    }
+
+    MOZ_ASSERT(XPCOM_MIN(temp, kMaxCapacity) >= aCapacity,
+               "should have hit the early return at the top");
+    aCapacity = XPCOM_MIN(temp, kMaxCapacity);
+  }
+
+  //
+  // several cases:
+  //
+  //  (1) we have a shared buffer (mFlags & F_SHARED)
+  //  (2) we have an owned buffer (mFlags & F_OWNED)
+  //  (3) we have a fixed buffer (mFlags & F_FIXED)
+  //  (4) we have a readonly buffer
+  //
+  // requiring that we in some cases preserve the data before creating
+  // a new buffer complicates things just a bit ;-)
+  //
+
+  size_type storageSize = (aCapacity + 1) * sizeof(char_type);
+
+  // case #1
+  if (mFlags & F_SHARED) {
+    nsStringBuffer* hdr = nsStringBuffer::FromData(mData);
+    if (!hdr->IsReadonly()) {
+      nsStringBuffer* newHdr = nsStringBuffer::Realloc(hdr, storageSize);
+      if (!newHdr) {
+        return false;  // out-of-memory (original header left intact)
+      }
+
+      hdr = newHdr;
+      mData = (char_type*)hdr->Data();
+      mFlags &= ~F_VOIDED;  // mutation clears voided flag
+      return true;
+    }
+  }
+
+  char_type* newData;
+  uint32_t newDataFlags;
+
+  // if we have a fixed buffer of sufficient size, then use it.  this helps
+  // avoid heap allocations.
+  if ((mFlags & F_CLASS_FIXED) &&
+      (aCapacity < AsFixedString(this)->mFixedCapacity)) {
+    newData = AsFixedString(this)->mFixedBuf;
+    newDataFlags = F_TERMINATED | F_FIXED;
+  } else {
+    // if we reach here then, we must allocate a new buffer.  we cannot
+    // make use of our F_OWNED or F_FIXED buffers because they are not
+    // large enough.
+
+    nsStringBuffer* newHdr =
+      nsStringBuffer::Alloc(storageSize).take();
+    if (!newHdr) {
+      return false;  // we are still in a consistent state
+    }
+
+    newData = (char_type*)newHdr->Data();
+    newDataFlags = F_TERMINATED | F_SHARED;
+  }
+
+  // save old data and flags
+  *aOldData = mData;
+  *aOldFlags = mFlags;
+
+  mData = newData;
+  SetDataFlags(newDataFlags);
+
+  // mLength does not change
+
+  // though we are not necessarily terminated at the moment, now is probably
+  // still the best time to set F_TERMINATED.
+
+  return true;
+}
+
+void
+nsTSubstring_CharT::Finalize()
+{
+  ::ReleaseData(mData, mFlags);
+  // mData, mLength, and mFlags are purposefully left dangling
+}
+
+bool
+nsTSubstring_CharT::ReplacePrep(index_type aCutStart,
+                                size_type aCutLength,
+                                size_type aNewLength)
+{
+  aCutLength = XPCOM_MIN(aCutLength, mLength - aCutStart);
+
+  mozilla::CheckedInt<size_type> newTotalLen = mLength;
+  newTotalLen += aNewLength;
+  newTotalLen -= aCutLength;
+  if (!newTotalLen.isValid()) {
+    return false;
+  }
+
+  if (aCutStart == mLength && Capacity() > newTotalLen.value()) {
+    mFlags &= ~F_VOIDED;
+    mData[newTotalLen.value()] = char_type(0);
+    mLength = newTotalLen.value();
+    return true;
+  }
+
+  return ReplacePrepInternal(aCutStart, aCutLength, aNewLength,
+                             newTotalLen.value());
+}
+
+bool
+nsTSubstring_CharT::ReplacePrepInternal(index_type aCutStart, size_type aCutLen,
+                                        size_type aFragLen, size_type aNewLen)
+{
+  char_type* oldData;
+  uint32_t oldFlags;
+  if (!MutatePrep(aNewLen, &oldData, &oldFlags)) {
+    return false;  // out-of-memory
+  }
+
+  if (oldData) {
+    // determine whether or not we need to copy part of the old string
+    // over to the new string.
+
+    if (aCutStart > 0) {
+      // copy prefix from old string
+      char_traits::copy(mData, oldData, aCutStart);
+    }
+
+    if (aCutStart + aCutLen < mLength) {
+      // copy suffix from old string to new offset
+      size_type from = aCutStart + aCutLen;
+      size_type fromLen = mLength - from;
+      uint32_t to = aCutStart + aFragLen;
+      char_traits::copy(mData + to, oldData + from, fromLen);
+    }
+
+    ::ReleaseData(oldData, oldFlags);
+  } else {
+    // original data remains intact
+
+    // determine whether or not we need to move part of the existing string
+    // to make room for the requested hole.
+    if (aFragLen != aCutLen && aCutStart + aCutLen < mLength) {
+      uint32_t from = aCutStart + aCutLen;
+      uint32_t fromLen = mLength - from;
+      uint32_t to = aCutStart + aFragLen;
+      char_traits::move(mData + to, mData + from, fromLen);
+    }
+  }
+
+  // add null terminator (mutable mData always has room for the null-
+  // terminator).
+  mData[aNewLen] = char_type(0);
+  mLength = aNewLen;
+
+  return true;
+}
+
+nsTSubstring_CharT::size_type
+nsTSubstring_CharT::Capacity() const
+{
+  // return 0 to indicate an immutable or 0-sized buffer
+
+  size_type capacity;
+  if (mFlags & F_SHARED) {
+    // if the string is readonly, then we pretend that it has no capacity.
+    nsStringBuffer* hdr = nsStringBuffer::FromData(mData);
+    if (hdr->IsReadonly()) {
+      capacity = 0;
+    } else {
+      capacity = (hdr->StorageSize() / sizeof(char_type)) - 1;
+    }
+  } else if (mFlags & F_FIXED) {
+    capacity = AsFixedString(this)->mFixedCapacity;
+  } else if (mFlags & F_OWNED) {
+    // we don't store the capacity of an adopted buffer because that would
+    // require an additional member field.  the best we can do is base the
+    // capacity on our length.  remains to be seen if this is the right
+    // trade-off.
+    capacity = mLength;
+  } else {
+    capacity = 0;
+  }
+
+  return capacity;
+}
+
+bool
+nsTSubstring_CharT::EnsureMutable(size_type aNewLen)
+{
+  if (aNewLen == size_type(-1) || aNewLen == mLength) {
+    if (mFlags & (F_FIXED | F_OWNED)) {
+      return true;
+    }
+    if ((mFlags & F_SHARED) &&
+        !nsStringBuffer::FromData(mData)->IsReadonly()) {
+      return true;
+    }
+
+    aNewLen = mLength;
+  }
+  return SetLength(aNewLen, mozilla::fallible);
+}
+
+// ---------------------------------------------------------------------------
+
+// This version of Assign is optimized for single-character assignment.
+void
+nsTSubstring_CharT::Assign(char_type aChar)
+{
+  if (!ReplacePrep(0, mLength, 1)) {
+    AllocFailed(mLength);
+  }
+
+  *mData = aChar;
+}
+
+bool
+nsTSubstring_CharT::Assign(char_type aChar, const fallible_t&)
+{
+  if (!ReplacePrep(0, mLength, 1)) {
+    return false;
+  }
+
+  *mData = aChar;
+  return true;
+}
+
+void
+nsTSubstring_CharT::Assign(const char_type* aData)
+{
+  if (!Assign(aData, mozilla::fallible)) {
+    AllocFailed(char_traits::length(aData));
+  }
+}
+
+bool
+nsTSubstring_CharT::Assign(const char_type* aData, const fallible_t&)
+{
+  return Assign(aData, size_type(-1), mozilla::fallible);
+}
+
+void
+nsTSubstring_CharT::Assign(const char_type* aData, size_type aLength)
+{
+  if (!Assign(aData, aLength, mozilla::fallible)) {
+    AllocFailed(aLength == size_type(-1) ? char_traits::length(aData)
+                                         : aLength);
+  }
+}
+
+bool
+nsTSubstring_CharT::Assign(const char_type* aData, size_type aLength,
+                           const fallible_t& aFallible)
+{
+  if (!aData || aLength == 0) {
+    Truncate();
+    return true;
+  }
+
+  if (aLength == size_type(-1)) {
+    aLength = char_traits::length(aData);
+  }
+
+  if (IsDependentOn(aData, aData + aLength)) {
+    return Assign(string_type(aData, aLength), aFallible);
+  }
+
+  if (!ReplacePrep(0, mLength, aLength)) {
+    return false;
+  }
+
+  char_traits::copy(mData, aData, aLength);
+  return true;
+}
+
+void
+nsTSubstring_CharT::AssignASCII(const char* aData, size_type aLength)
+{
+  if (!AssignASCII(aData, aLength, mozilla::fallible)) {
+    AllocFailed(aLength);
+  }
+}
+
+bool
+nsTSubstring_CharT::AssignASCII(const char* aData, size_type aLength,
+                                const fallible_t& aFallible)
+{
+  // A Unicode string can't depend on an ASCII string buffer,
+  // so this dependence check only applies to CStrings.
+#ifdef CharT_is_char
+  if (IsDependentOn(aData, aData + aLength)) {
+    return Assign(string_type(aData, aLength), aFallible);
+  }
+#endif
+
+  if (!ReplacePrep(0, mLength, aLength)) {
+    return false;
+  }
+
+  char_traits::copyASCII(mData, aData, aLength);
+  return true;
+}
+
+void
+nsTSubstring_CharT::AssignLiteral(const char_type* aData, size_type aLength)
+{
+  ::ReleaseData(mData, mFlags);
+  mData = const_cast<char_type*>(aData);
+  mLength = aLength;
+  SetDataFlags(F_TERMINATED | F_LITERAL);
+}
+
+void
+nsTSubstring_CharT::Assign(const self_type& aStr)
+{
+  if (!Assign(aStr, mozilla::fallible)) {
+    AllocFailed(aStr.Length());
+  }
+}
+
+bool
+nsTSubstring_CharT::Assign(const self_type& aStr, const fallible_t& aFallible)
+{
+  // |aStr| could be sharable. We need to check its flags to know how to
+  // deal with it.
+
+  if (&aStr == this) {
+    return true;
+  }
+
+  if (!aStr.mLength) {
+    Truncate();
+    mFlags |= aStr.mFlags & F_VOIDED;
+    return true;
+  }
+
+  if (aStr.mFlags & F_SHARED) {
+    // nice! we can avoid a string copy :-)
+
+    // |aStr| should be null-terminated
+    NS_ASSERTION(aStr.mFlags & F_TERMINATED, "shared, but not terminated");
+
+    ::ReleaseData(mData, mFlags);
+
+    mData = aStr.mData;
+    mLength = aStr.mLength;
+    SetDataFlags(F_TERMINATED | F_SHARED);
+
+    // get an owning reference to the mData
+    nsStringBuffer::FromData(mData)->AddRef();
+    return true;
+  } else if (aStr.mFlags & F_LITERAL) {
+    MOZ_ASSERT(aStr.mFlags & F_TERMINATED, "Unterminated literal");
+
+    AssignLiteral(aStr.mData, aStr.mLength);
+    return true;
+  }
+
+  // else, treat this like an ordinary assignment.
+  return Assign(aStr.Data(), aStr.Length(), aFallible);
+}
+
+void
+nsTSubstring_CharT::Assign(const substring_tuple_type& aTuple)
+{
+  if (!Assign(aTuple, mozilla::fallible)) {
+    AllocFailed(aTuple.Length());
+  }
+}
+
+bool
+nsTSubstring_CharT::Assign(const substring_tuple_type& aTuple,
+                           const fallible_t& aFallible)
+{
+  if (aTuple.IsDependentOn(mData, mData + mLength)) {
+    // take advantage of sharing here...
+    return Assign(string_type(aTuple), aFallible);
+  }
+
+  size_type length = aTuple.Length();
+
+  // don't use ReplacePrep here because it changes the length
+  char_type* oldData;
+  uint32_t oldFlags;
+  if (!MutatePrep(length, &oldData, &oldFlags)) {
+    return false;
+  }
+
+  if (oldData) {
+    ::ReleaseData(oldData, oldFlags);
+  }
+
+  aTuple.WriteTo(mData, length);
+  mData[length] = 0;
+  mLength = length;
+  return true;
+}
+
+void
+nsTSubstring_CharT::Adopt(char_type* aData, size_type aLength)
+{
+  if (aData) {
+    ::ReleaseData(mData, mFlags);
+
+    if (aLength == size_type(-1)) {
+      aLength = char_traits::length(aData);
+    }
+
+    MOZ_RELEASE_ASSERT(CheckCapacity(aLength), "adopting a too-long string");
+
+    mData = aData;
+    mLength = aLength;
+    SetDataFlags(F_TERMINATED | F_OWNED);
+
+    STRING_STAT_INCREMENT(Adopt);
+    // Treat this as construction of a "StringAdopt" object for leak
+    // tracking purposes.
+    MOZ_LOG_CTOR(mData, "StringAdopt", 1);
+  } else {
+    SetIsVoid(true);
+  }
+}
+
+
+// This version of Replace is optimized for single-character replacement.
+void
+nsTSubstring_CharT::Replace(index_type aCutStart, size_type aCutLength,
+                            char_type aChar)
+{
+  aCutStart = XPCOM_MIN(aCutStart, Length());
+
+  if (ReplacePrep(aCutStart, aCutLength, 1)) {
+    mData[aCutStart] = aChar;
+  }
+}
+
+bool
+nsTSubstring_CharT::Replace(index_type aCutStart, size_type aCutLength,
+                            char_type aChar,
+                            const fallible_t&)
+{
+  aCutStart = XPCOM_MIN(aCutStart, Length());
+
+  if (!ReplacePrep(aCutStart, aCutLength, 1)) {
+    return false;
+  }
+
+  mData[aCutStart] = aChar;
+
+  return true;
+}
+
+void
+nsTSubstring_CharT::Replace(index_type aCutStart, size_type aCutLength,
+                            const char_type* aData, size_type aLength)
+{
+  if (!Replace(aCutStart, aCutLength, aData, aLength,
+               mozilla::fallible)) {
+    AllocFailed(Length() - aCutLength + 1);
+  }
+}
+
+bool
+nsTSubstring_CharT::Replace(index_type aCutStart, size_type aCutLength,
+                            const char_type* aData, size_type aLength,
+                            const fallible_t& aFallible)
+{
+  // unfortunately, some callers pass null :-(
+  if (!aData) {
+    aLength = 0;
+  } else {
+    if (aLength == size_type(-1)) {
+      aLength = char_traits::length(aData);
+    }
+
+    if (IsDependentOn(aData, aData + aLength)) {
+      nsTAutoString_CharT temp(aData, aLength);
+      return Replace(aCutStart, aCutLength, temp, aFallible);
+    }
+  }
+
+  aCutStart = XPCOM_MIN(aCutStart, Length());
+
+  bool ok = ReplacePrep(aCutStart, aCutLength, aLength);
+  if (!ok) {
+    return false;
+  }
+
+  if (aLength > 0) {
+    char_traits::copy(mData + aCutStart, aData, aLength);
+  }
+
+  return true;
+}
+
+void
+nsTSubstring_CharT::ReplaceASCII(index_type aCutStart, size_type aCutLength,
+                                 const char* aData, size_type aLength)
+{
+  if (!ReplaceASCII(aCutStart, aCutLength, aData, aLength, mozilla::fallible)) {
+    AllocFailed(Length() - aCutLength + 1);
+  }
+}
+
+bool
+nsTSubstring_CharT::ReplaceASCII(index_type aCutStart, size_type aCutLength,
+                                 const char* aData, size_type aLength,
+                                 const fallible_t& aFallible)
+{
+  if (aLength == size_type(-1)) {
+    aLength = strlen(aData);
+  }
+
+  // A Unicode string can't depend on an ASCII string buffer,
+  // so this dependence check only applies to CStrings.
+#ifdef CharT_is_char
+  if (IsDependentOn(aData, aData + aLength)) {
+    nsTAutoString_CharT temp(aData, aLength);
+    return Replace(aCutStart, aCutLength, temp, aFallible);
+  }
+#endif
+
+  aCutStart = XPCOM_MIN(aCutStart, Length());
+
+  bool ok = ReplacePrep(aCutStart, aCutLength, aLength);
+  if (!ok) {
+    return false;
+  }
+
+  if (aLength > 0) {
+    char_traits::copyASCII(mData + aCutStart, aData, aLength);
+  }
+
+  return true;
+}
+
+void
+nsTSubstring_CharT::Replace(index_type aCutStart, size_type aCutLength,
+                            const substring_tuple_type& aTuple)
+{
+  if (aTuple.IsDependentOn(mData, mData + mLength)) {
+    nsTAutoString_CharT temp(aTuple);
+    Replace(aCutStart, aCutLength, temp);
+    return;
+  }
+
+  size_type length = aTuple.Length();
+
+  aCutStart = XPCOM_MIN(aCutStart, Length());
+
+  if (ReplacePrep(aCutStart, aCutLength, length) && length > 0) {
+    aTuple.WriteTo(mData + aCutStart, length);
+  }
+}
+
+void
+nsTSubstring_CharT::ReplaceLiteral(index_type aCutStart, size_type aCutLength,
+                                   const char_type* aData, size_type aLength)
+{
+  aCutStart = XPCOM_MIN(aCutStart, Length());
+
+  if (!aCutStart && aCutLength == Length()) {
+    AssignLiteral(aData, aLength);
+  } else if (ReplacePrep(aCutStart, aCutLength, aLength) && aLength > 0) {
+    char_traits::copy(mData + aCutStart, aData, aLength);
+  }
+}
+
+void
+nsTSubstring_CharT::SetCapacity(size_type aCapacity)
+{
+  if (!SetCapacity(aCapacity, mozilla::fallible)) {
+    AllocFailed(aCapacity);
+  }
+}
+
+bool
+nsTSubstring_CharT::SetCapacity(size_type aCapacity, const fallible_t&)
+{
+  // capacity does not include room for the terminating null char
+
+  // if our capacity is reduced to zero, then free our buffer.
+  if (aCapacity == 0) {
+    ::ReleaseData(mData, mFlags);
+    mData = char_traits::sEmptyBuffer;
+    mLength = 0;
+    SetDataFlags(F_TERMINATED);
+    return true;
+  }
+
+  char_type* oldData;
+  uint32_t oldFlags;
+  if (!MutatePrep(aCapacity, &oldData, &oldFlags)) {
+    return false;  // out-of-memory
+  }
+
+  // compute new string length
+  size_type newLen = XPCOM_MIN(mLength, aCapacity);
+
+  if (oldData) {
+    // preserve old data
+    if (mLength > 0) {
+      char_traits::copy(mData, oldData, newLen);
+    }
+
+    ::ReleaseData(oldData, oldFlags);
+  }
+
+  // adjust mLength if our buffer shrunk down in size
+  if (newLen < mLength) {
+    mLength = newLen;
+  }
+
+  // always null-terminate here, even if the buffer got longer.  this is
+  // for backwards compat with the old string implementation.
+  mData[aCapacity] = char_type(0);
+
+  return true;
+}
+
+void
+nsTSubstring_CharT::SetLength(size_type aLength)
+{
+  SetCapacity(aLength);
+  mLength = aLength;
+}
+
+bool
+nsTSubstring_CharT::SetLength(size_type aLength, const fallible_t& aFallible)
+{
+  if (!SetCapacity(aLength, aFallible)) {
+    return false;
+  }
+
+  mLength = aLength;
+  return true;
+}
+
+void
+nsTSubstring_CharT::SetIsVoid(bool aVal)
+{
+  if (aVal) {
+    Truncate();
+    mFlags |= F_VOIDED;
+  } else {
+    mFlags &= ~F_VOIDED;
+  }
+}
+
+bool
+nsTSubstring_CharT::Equals(const self_type& aStr) const
+{
+  return mLength == aStr.mLength &&
+         char_traits::compare(mData, aStr.mData, mLength) == 0;
+}
+
+bool
+nsTSubstring_CharT::Equals(const self_type& aStr,
+                           const comparator_type& aComp) const
+{
+  return mLength == aStr.mLength &&
+         aComp(mData, aStr.mData, mLength, aStr.mLength) == 0;
+}
+
+bool
+nsTSubstring_CharT::Equals(const char_type* aData) const
+{
+  // unfortunately, some callers pass null :-(
+  if (!aData) {
+    NS_NOTREACHED("null data pointer");
+    return mLength == 0;
+  }
+
+  // XXX avoid length calculation?
+  size_type length = char_traits::length(aData);
+  return mLength == length &&
+         char_traits::compare(mData, aData, mLength) == 0;
+}
+
+bool
+nsTSubstring_CharT::Equals(const char_type* aData,
+                           const comparator_type& aComp) const
+{
+  // unfortunately, some callers pass null :-(
+  if (!aData) {
+    NS_NOTREACHED("null data pointer");
+    return mLength == 0;
+  }
+
+  // XXX avoid length calculation?
+  size_type length = char_traits::length(aData);
+  return mLength == length && aComp(mData, aData, mLength, length) == 0;
+}
+
+bool
+nsTSubstring_CharT::EqualsASCII(const char* aData, size_type aLen) const
+{
+  return mLength == aLen &&
+         char_traits::compareASCII(mData, aData, aLen) == 0;
+}
+
+bool
+nsTSubstring_CharT::EqualsASCII(const char* aData) const
+{
+  return char_traits::compareASCIINullTerminated(mData, mLength, aData) == 0;
+}
+
+bool
+nsTSubstring_CharT::LowerCaseEqualsASCII(const char* aData,
+                                         size_type aLen) const
+{
+  return mLength == aLen &&
+         char_traits::compareLowerCaseToASCII(mData, aData, aLen) == 0;
+}
+
+bool
+nsTSubstring_CharT::LowerCaseEqualsASCII(const char* aData) const
+{
+  return char_traits::compareLowerCaseToASCIINullTerminated(mData,
+                                                            mLength,
+                                                            aData) == 0;
+}
+
+nsTSubstring_CharT::size_type
+nsTSubstring_CharT::CountChar(char_type aChar) const
+{
+  const char_type* start = mData;
+  const char_type* end   = mData + mLength;
+
+  return NS_COUNT(start, end, aChar);
+}
+
+int32_t
+nsTSubstring_CharT::FindChar(char_type aChar, index_type aOffset) const
+{
+  if (aOffset < mLength) {
+    const char_type* result = char_traits::find(mData + aOffset,
+                                                mLength - aOffset, aChar);
+    if (result) {
+      return result - mData;
+    }
+  }
+  return -1;
+}
+
+void
+nsTSubstring_CharT::StripChar(char_type aChar, int32_t aOffset)
+{
+  if (mLength == 0 || aOffset >= int32_t(mLength)) {
+    return;
+  }
+
+  if (!EnsureMutable()) { // XXX do this lazily?
+    AllocFailed(mLength);
+  }
+
+  // XXX(darin): this code should defer writing until necessary.
+
+  char_type* to   = mData + aOffset;
+  char_type* from = mData + aOffset;
+  char_type* end  = mData + mLength;
+
+  while (from < end) {
+    char_type theChar = *from++;
+    if (aChar != theChar) {
+      *to++ = theChar;
+    }
+  }
+  *to = char_type(0); // add the null
+  mLength = to - mData;
+}
+
+void
+nsTSubstring_CharT::StripChars(const char_type* aChars, uint32_t aOffset)
+{
+  if (aOffset >= uint32_t(mLength)) {
+    return;
+  }
+
+  if (!EnsureMutable()) { // XXX do this lazily?
+    AllocFailed(mLength);
+  }
+
+  // XXX(darin): this code should defer writing until necessary.
+
+  char_type* to   = mData + aOffset;
+  char_type* from = mData + aOffset;
+  char_type* end  = mData + mLength;
+
+  while (from < end) {
+    char_type theChar = *from++;
+    const char_type* test = aChars;
+
+    for (; *test && *test != theChar; ++test);
+
+    if (!*test) {
+      // Not stripped, copy this char.
+      *to++ = theChar;
+    }
+  }
+  *to = char_type(0); // add the null
+  mLength = to - mData;
+}
+
+int
+nsTSubstring_CharT::AppendFunc(void* aArg, const char* aStr, uint32_t aLen)
+{
+  self_type* self = static_cast<self_type*>(aArg);
+
+  // NSPR sends us the final null terminator even though we don't want it
+  if (aLen && aStr[aLen - 1] == '\0') {
+    --aLen;
+  }
+
+  self->AppendASCII(aStr, aLen);
+
+  return aLen;
+}
+
+void
+nsTSubstring_CharT::AppendPrintf(const char* aFormat, ...)
+{
+  va_list ap;
+  va_start(ap, aFormat);
+  uint32_t r = PR_vsxprintf(AppendFunc, this, aFormat, ap);
+  if (r == (uint32_t)-1) {
+    NS_RUNTIMEABORT("Allocation or other failure in PR_vsxprintf");
+  }
+  va_end(ap);
+}
+
+void
+nsTSubstring_CharT::AppendPrintf(const char* aFormat, va_list aAp)
+{
+  uint32_t r = PR_vsxprintf(AppendFunc, this, aFormat, aAp);
+  if (r == (uint32_t)-1) {
+    NS_RUNTIMEABORT("Allocation or other failure in PR_vsxprintf");
+  }
+}
+
+/* hack to make sure we define FormatWithoutTrailingZeros only once */
+#ifdef CharT_is_PRUnichar
+// Returns the length of the formatted aDouble in aBuf.
+static int
+FormatWithoutTrailingZeros(char (&aBuf)[40], double aDouble,
+                           int aPrecision)
+{
+  static const DoubleToStringConverter converter(DoubleToStringConverter::UNIQUE_ZERO |
+                                                 DoubleToStringConverter::EMIT_POSITIVE_EXPONENT_SIGN,
+                                                 "Infinity",
+                                                 "NaN",
+                                                 'e',
+                                                 -6, 21,
+                                                 6, 1);
+  double_conversion::StringBuilder builder(aBuf, sizeof(aBuf));
+  bool exponential_notation = false;
+  converter.ToPrecision(aDouble, aPrecision, &exponential_notation, &builder);
+  int length = builder.position();
+  char* formattedDouble = builder.Finalize();
+
+  // If we have a shorter string than aPrecision, it means we have a special
+  // value (NaN or Infinity).  All other numbers will be formatted with at
+  // least aPrecision digits.
+  if (length <= aPrecision) {
+    return length;
+  }
+
+  char* end = formattedDouble + length;
+  char* decimalPoint = strchr(aBuf, '.');
+  // No trailing zeros to remove.
+  if (!decimalPoint) {
+    return length;
+  }
+
+  if (MOZ_UNLIKELY(exponential_notation)) {
+    // We need to check for cases like 1.00000e-10 (yes, this is
+    // disgusting).
+    char* exponent = end - 1;
+    for (; ; --exponent) {
+      if (*exponent == 'e') {
+        break;
+      }
+    }
+    char* zerosBeforeExponent = exponent - 1;
+    for (; zerosBeforeExponent != decimalPoint; --zerosBeforeExponent) {
+      if (*zerosBeforeExponent != '0') {
+        break;
+      }
+    }
+    if (zerosBeforeExponent == decimalPoint) {
+      --zerosBeforeExponent;
+    }
+    // Slide the exponent to the left over the trailing zeros.  Don't
+    // worry about copying the trailing NUL character.
+    size_t exponentSize = end - exponent;
+    memmove(zerosBeforeExponent + 1, exponent, exponentSize);
+    length -= exponent - (zerosBeforeExponent + 1);
+  } else {
+    char* trailingZeros = end - 1;
+    for (; trailingZeros != decimalPoint; --trailingZeros) {
+      if (*trailingZeros != '0') {
+        break;
+      }
+    }
+    if (trailingZeros == decimalPoint) {
+      --trailingZeros;
+    }
+    length -= end - (trailingZeros + 1);
+  }
+
+  return length;
+}
+#endif /* CharT_is_PRUnichar */
+
+void
+nsTSubstring_CharT::AppendFloat(float aFloat)
+{
+  char buf[40];
+  int length = FormatWithoutTrailingZeros(buf, aFloat, 6);
+  AppendASCII(buf, length);
+}
+
+void
+nsTSubstring_CharT::AppendFloat(double aFloat)
+{
+  char buf[40];
+  int length = FormatWithoutTrailingZeros(buf, aFloat, 15);
+  AppendASCII(buf, length);
+}
+
+size_t
+nsTSubstring_CharT::SizeOfExcludingThisIfUnshared(
+    mozilla::MallocSizeOf aMallocSizeOf) const
+{
+  if (mFlags & F_SHARED) {
+    return nsStringBuffer::FromData(mData)->
+      SizeOfIncludingThisIfUnshared(aMallocSizeOf);
+  }
+  if (mFlags & F_OWNED) {
+    return aMallocSizeOf(mData);
+  }
+
+  // If we reach here, exactly one of the following must be true:
+  // - F_VOIDED is set, and mData points to sEmptyBuffer;
+  // - F_FIXED is set, and mData points to a buffer within a string
+  //   object (e.g. nsAutoString);
+  // - None of F_SHARED, F_OWNED, F_FIXED is set, and mData points to a buffer
+  //   owned by something else.
+  //
+  // In all three cases, we don't measure it.
+  return 0;
+}
+
+size_t
+nsTSubstring_CharT::SizeOfExcludingThisEvenIfShared(
+    mozilla::MallocSizeOf aMallocSizeOf) const
+{
+  // This is identical to SizeOfExcludingThisIfUnshared except for the
+  // F_SHARED case.
+  if (mFlags & F_SHARED) {
+    return nsStringBuffer::FromData(mData)->
+      SizeOfIncludingThisEvenIfShared(aMallocSizeOf);
+  }
+  if (mFlags & F_OWNED) {
+    return aMallocSizeOf(mData);
+  }
+  return 0;
+}
+
+size_t
+nsTSubstring_CharT::SizeOfIncludingThisIfUnshared(
+    mozilla::MallocSizeOf aMallocSizeOf) const
+{
+  return aMallocSizeOf(this) + SizeOfExcludingThisIfUnshared(aMallocSizeOf);
+}
+
+size_t
+nsTSubstring_CharT::SizeOfIncludingThisEvenIfShared(
+    mozilla::MallocSizeOf aMallocSizeOf) const
+{
+  return aMallocSizeOf(this) + SizeOfExcludingThisEvenIfShared(aMallocSizeOf);
+}
+
diff --git a/xpcom/string/nsTSubstring.h b/xpcom/string/nsTSubstring.h
new file mode 100644
index 000000000..a08036b1f
--- /dev/null
+++ b/xpcom/string/nsTSubstring.h
@@ -0,0 +1,1186 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+// IWYU pragma: private, include "nsString.h"
+
+#include "mozilla/Casting.h"
+#include "mozilla/MemoryReporting.h"
+
+#ifndef MOZILLA_INTERNAL_API
+#error Cannot use internal string classes without MOZILLA_INTERNAL_API defined. Use the frozen header nsStringAPI.h instead.
+#endif
+
+/**
+ * The base for string comparators
+ */
+class nsTStringComparator_CharT
+{
+public:
+  typedef CharT char_type;
+
+  nsTStringComparator_CharT()
+  {
+  }
+
+  virtual int operator()(const char_type*, const char_type*,
+                         uint32_t, uint32_t) const = 0;
+};
+
+
+/**
+ * The default string comparator (case-sensitive comparision)
+ */
+class nsTDefaultStringComparator_CharT
+  : public nsTStringComparator_CharT
+{
+public:
+  typedef CharT char_type;
+
+  nsTDefaultStringComparator_CharT()
+  {
+  }
+
+  virtual int operator()(const char_type*, const char_type*,
+                         uint32_t, uint32_t) const override;
+};
+
+/**
+ * nsTSubstring is the most abstract class in the string hierarchy. It
+ * represents a single contiguous array of characters, which may or may not
+ * be null-terminated. This type is not instantiated directly.  A sub-class
+ * is instantiated instead.  For example, see nsTString.
+ *
+ * NAMES:
+ *   nsAString for wide characters
+ *   nsACString for narrow characters
+ *
+ * Many of the accessors on nsTSubstring are inlined as an optimization.
+ */
+class nsTSubstring_CharT
+{
+public:
+  typedef mozilla::fallible_t                 fallible_t;
+
+  typedef CharT                               char_type;
+
+  typedef nsCharTraits<char_type>             char_traits;
+  typedef char_traits::incompatible_char_type incompatible_char_type;
+
+  typedef nsTSubstring_CharT                  self_type;
+  typedef self_type                           abstract_string_type;
+  typedef self_type                           base_string_type;
+
+  typedef self_type                           substring_type;
+  typedef nsTSubstringTuple_CharT             substring_tuple_type;
+  typedef nsTString_CharT                     string_type;
+
+  typedef nsReadingIterator<char_type>        const_iterator;
+  typedef nsWritingIterator<char_type>        iterator;
+
+  typedef nsTStringComparator_CharT           comparator_type;
+
+  typedef char_type*                          char_iterator;
+  typedef const char_type*                    const_char_iterator;
+
+  typedef uint32_t                            size_type;
+  typedef uint32_t                            index_type;
+
+public:
+
+  // this acts like a virtual destructor
+  ~nsTSubstring_CharT()
+  {
+    Finalize();
+  }
+
+  /**
+   * reading iterators
+   */
+
+  const_char_iterator BeginReading() const
+  {
+    return mData;
+  }
+  const_char_iterator EndReading() const
+  {
+    return mData + mLength;
+  }
+
+  /**
+   * deprecated reading iterators
+   */
+
+  const_iterator& BeginReading(const_iterator& aIter) const
+  {
+    aIter.mStart = mData;
+    aIter.mEnd = mData + mLength;
+    aIter.mPosition = aIter.mStart;
+    return aIter;
+  }
+
+  const_iterator& EndReading(const_iterator& aIter) const
+  {
+    aIter.mStart = mData;
+    aIter.mEnd = mData + mLength;
+    aIter.mPosition = aIter.mEnd;
+    return aIter;
+  }
+
+  const_char_iterator& BeginReading(const_char_iterator& aIter) const
+  {
+    return aIter = mData;
+  }
+
+  const_char_iterator& EndReading(const_char_iterator& aIter) const
+  {
+    return aIter = mData + mLength;
+  }
+
+
+  /**
+   * writing iterators
+   */
+
+  char_iterator BeginWriting()
+  {
+    if (!EnsureMutable()) {
+      AllocFailed(mLength);
+    }
+
+    return mData;
+  }
+
+  char_iterator BeginWriting(const fallible_t&)
+  {
+    return EnsureMutable() ? mData : char_iterator(0);
+  }
+
+  char_iterator EndWriting()
+  {
+    if (!EnsureMutable()) {
+      AllocFailed(mLength);
+    }
+
+    return mData + mLength;
+  }
+
+  char_iterator EndWriting(const fallible_t&)
+  {
+    return EnsureMutable() ? (mData + mLength) : char_iterator(0);
+  }
+
+  char_iterator& BeginWriting(char_iterator& aIter)
+  {
+    return aIter = BeginWriting();
+  }
+
+  char_iterator& BeginWriting(char_iterator& aIter, const fallible_t& aFallible)
+  {
+    return aIter = BeginWriting(aFallible);
+  }
+
+  char_iterator& EndWriting(char_iterator& aIter)
+  {
+    return aIter = EndWriting();
+  }
+
+  char_iterator& EndWriting(char_iterator& aIter, const fallible_t& aFallible)
+  {
+    return aIter = EndWriting(aFallible);
+  }
+
+  /**
+   * deprecated writing iterators
+   */
+
+  iterator& BeginWriting(iterator& aIter)
+  {
+    char_type* data = BeginWriting();
+    aIter.mStart = data;
+    aIter.mEnd = data + mLength;
+    aIter.mPosition = aIter.mStart;
+    return aIter;
+  }
+
+  iterator& EndWriting(iterator& aIter)
+  {
+    char_type* data = BeginWriting();
+    aIter.mStart = data;
+    aIter.mEnd = data + mLength;
+    aIter.mPosition = aIter.mEnd;
+    return aIter;
+  }
+
+  /**
+   * accessors
+   */
+
+  // returns pointer to string data (not necessarily null-terminated)
+#if defined(CharT_is_PRUnichar) && defined(MOZ_USE_CHAR16_WRAPPER)
+  char16ptr_t Data() const
+#else
+  const char_type* Data() const
+#endif
+  {
+    return mData;
+  }
+
+  size_type Length() const
+  {
+    return mLength;
+  }
+
+  uint32_t Flags() const
+  {
+    return mFlags;
+  }
+
+  bool IsEmpty() const
+  {
+    return mLength == 0;
+  }
+
+  bool IsLiteral() const
+  {
+    return (mFlags & F_LITERAL) != 0;
+  }
+
+  bool IsVoid() const
+  {
+    return (mFlags & F_VOIDED) != 0;
+  }
+
+  bool IsTerminated() const
+  {
+    return (mFlags & F_TERMINATED) != 0;
+  }
+
+  char_type CharAt(index_type aIndex) const
+  {
+    NS_ASSERTION(aIndex < mLength, "index exceeds allowable range");
+    return mData[aIndex];
+  }
+
+  char_type operator[](index_type aIndex) const
+  {
+    return CharAt(aIndex);
+  }
+
+  char_type First() const
+  {
+    NS_ASSERTION(mLength > 0, "|First()| called on an empty string");
+    return mData[0];
+  }
+
+  inline   char_type Last() const
+  {
+    NS_ASSERTION(mLength > 0, "|Last()| called on an empty string");
+    return mData[mLength - 1];
+  }
+
+  size_type NS_FASTCALL CountChar(char_type) const;
+  int32_t NS_FASTCALL FindChar(char_type, index_type aOffset = 0) const;
+
+  inline bool Contains(char_type aChar) const
+  {
+    return FindChar(aChar) != kNotFound;
+  }
+
+  /**
+   * equality
+   */
+
+  bool NS_FASTCALL Equals(const self_type&) const;
+  bool NS_FASTCALL Equals(const self_type&, const comparator_type&) const;
+
+  bool NS_FASTCALL Equals(const char_type* aData) const;
+  bool NS_FASTCALL Equals(const char_type* aData,
+                          const comparator_type& aComp) const;
+
+#if defined(CharT_is_PRUnichar) && defined(MOZ_USE_CHAR16_WRAPPER)
+  bool NS_FASTCALL Equals(char16ptr_t aData) const
+  {
+    return Equals(static_cast<const char16_t*>(aData));
+  }
+  bool NS_FASTCALL Equals(char16ptr_t aData, const comparator_type& aComp) const
+  {
+    return Equals(static_cast<const char16_t*>(aData), aComp);
+  }
+#endif
+
+  /**
+   * An efficient comparison with ASCII that can be used even
+   * for wide strings. Call this version when you know the
+   * length of 'data'.
+   */
+  bool NS_FASTCALL EqualsASCII(const char* aData, size_type aLen) const;
+  /**
+   * An efficient comparison with ASCII that can be used even
+   * for wide strings. Call this version when 'data' is
+   * null-terminated.
+   */
+  bool NS_FASTCALL EqualsASCII(const char* aData) const;
+
+  // EqualsLiteral must ONLY be applied to an actual literal string, or
+  // a char array *constant* declared without an explicit size.
+  // Do not attempt to use it with a regular char* pointer, or with a
+  // non-constant char array variable. Use EqualsASCII for them.
+  // The template trick to acquire the array length at compile time without
+  // using a macro is due to Corey Kosak, with much thanks.
+  template<int N>
+  inline bool EqualsLiteral(const char (&aStr)[N]) const
+  {
+    return EqualsASCII(aStr, N - 1);
+  }
+
+  // The LowerCaseEquals methods compare the ASCII-lowercase version of
+  // this string (lowercasing only ASCII uppercase characters) to some
+  // ASCII/Literal string. The ASCII string is *not* lowercased for
+  // you. If you compare to an ASCII or literal string that contains an
+  // uppercase character, it is guaranteed to return false. We will
+  // throw assertions too.
+  bool NS_FASTCALL LowerCaseEqualsASCII(const char* aData,
+                                        size_type aLen) const;
+  bool NS_FASTCALL LowerCaseEqualsASCII(const char* aData) const;
+
+  // LowerCaseEqualsLiteral must ONLY be applied to an actual
+  // literal string, or a char array *constant* declared without an
+  // explicit size.  Do not attempt to use it with a regular char*
+  // pointer, or with a non-constant char array variable. Use
+  // LowerCaseEqualsASCII for them.
+  template<int N>
+  inline bool LowerCaseEqualsLiteral(const char (&aStr)[N]) const
+  {
+    return LowerCaseEqualsASCII(aStr, N - 1);
+  }
+
+  /**
+   * assignment
+   */
+
+  void NS_FASTCALL Assign(char_type aChar);
+  MOZ_MUST_USE bool NS_FASTCALL Assign(char_type aChar, const fallible_t&);
+
+  void NS_FASTCALL Assign(const char_type* aData);
+  MOZ_MUST_USE bool NS_FASTCALL Assign(const char_type* aData,
+                                       const fallible_t&);
+
+  void NS_FASTCALL Assign(const char_type* aData, size_type aLength);
+  MOZ_MUST_USE bool NS_FASTCALL Assign(const char_type* aData,
+                                       size_type aLength, const fallible_t&);
+
+  void NS_FASTCALL Assign(const self_type&);
+  MOZ_MUST_USE bool NS_FASTCALL Assign(const self_type&, const fallible_t&);
+
+  void NS_FASTCALL Assign(const substring_tuple_type&);
+  MOZ_MUST_USE bool NS_FASTCALL Assign(const substring_tuple_type&,
+                                       const fallible_t&);
+
+#if defined(CharT_is_PRUnichar) && defined(MOZ_USE_CHAR16_WRAPPER)
+  void Assign(char16ptr_t aData)
+  {
+    Assign(static_cast<const char16_t*>(aData));
+  }
+
+  void Assign(char16ptr_t aData, size_type aLength)
+  {
+    Assign(static_cast<const char16_t*>(aData), aLength);
+  }
+
+  MOZ_MUST_USE bool Assign(char16ptr_t aData, size_type aLength,
+                           const fallible_t& aFallible)
+  {
+    return Assign(static_cast<const char16_t*>(aData), aLength,
+                  aFallible);
+  }
+#endif
+
+  void NS_FASTCALL AssignASCII(const char* aData, size_type aLength);
+  MOZ_MUST_USE bool NS_FASTCALL AssignASCII(const char* aData,
+                                            size_type aLength,
+                                            const fallible_t&);
+
+  void NS_FASTCALL AssignASCII(const char* aData)
+  {
+    AssignASCII(aData, mozilla::AssertedCast<size_type, size_t>(strlen(aData)));
+  }
+  MOZ_MUST_USE bool NS_FASTCALL AssignASCII(const char* aData,
+                                            const fallible_t& aFallible)
+  {
+    return AssignASCII(aData,
+                       mozilla::AssertedCast<size_type, size_t>(strlen(aData)),
+                       aFallible);
+  }
+
+  // AssignLiteral must ONLY be applied to an actual literal string, or
+  // a char array *constant* declared without an explicit size.
+  // Do not attempt to use it with a regular char* pointer, or with a
+  // non-constant char array variable. Use AssignASCII for those.
+  // There are not fallible version of these methods because they only really
+  // apply to small allocations that we wouldn't want to check anyway.
+  template<int N>
+  void AssignLiteral(const char_type (&aStr)[N])
+  {
+    AssignLiteral(aStr, N - 1);
+  }
+#ifdef CharT_is_PRUnichar
+  template<int N>
+  void AssignLiteral(const char (&aStr)[N])
+  {
+    AssignASCII(aStr, N - 1);
+  }
+#endif
+
+  self_type& operator=(char_type aChar)
+  {
+    Assign(aChar);
+    return *this;
+  }
+  self_type& operator=(const char_type* aData)
+  {
+    Assign(aData);
+    return *this;
+  }
+#if defined(CharT_is_PRUnichar) && defined(MOZ_USE_CHAR16_WRAPPER)
+  self_type& operator=(char16ptr_t aData)
+  {
+    Assign(aData);
+    return *this;
+  }
+#endif
+  self_type& operator=(const self_type& aStr)
+  {
+    Assign(aStr);
+    return *this;
+  }
+  self_type& operator=(const substring_tuple_type& aTuple)
+  {
+    Assign(aTuple);
+    return *this;
+  }
+
+  void NS_FASTCALL Adopt(char_type* aData, size_type aLength = size_type(-1));
+
+
+  /**
+   * buffer manipulation
+   */
+
+  void NS_FASTCALL Replace(index_type aCutStart, size_type aCutLength,
+                           char_type aChar);
+  MOZ_MUST_USE bool NS_FASTCALL Replace(index_type aCutStart,
+                                        size_type aCutLength,
+                                        char_type aChar,
+                                        const fallible_t&);
+  void NS_FASTCALL Replace(index_type aCutStart, size_type aCutLength,
+                           const char_type* aData,
+                           size_type aLength = size_type(-1));
+  MOZ_MUST_USE bool NS_FASTCALL Replace(index_type aCutStart,
+                                        size_type aCutLength,
+                                        const char_type* aData,
+                                        size_type aLength,
+                                        const fallible_t&);
+  void Replace(index_type aCutStart, size_type aCutLength,
+               const self_type& aStr)
+  {
+    Replace(aCutStart, aCutLength, aStr.Data(), aStr.Length());
+  }
+  MOZ_MUST_USE bool Replace(index_type aCutStart,
+                            size_type aCutLength,
+                            const self_type& aStr,
+                            const fallible_t& aFallible)
+  {
+    return Replace(aCutStart, aCutLength, aStr.Data(), aStr.Length(),
+                   aFallible);
+  }
+  void NS_FASTCALL Replace(index_type aCutStart, size_type aCutLength,
+                           const substring_tuple_type& aTuple);
+
+  void NS_FASTCALL ReplaceASCII(index_type aCutStart, size_type aCutLength,
+                                const char* aData,
+                                size_type aLength = size_type(-1));
+
+  MOZ_MUST_USE bool NS_FASTCALL ReplaceASCII(index_type aCutStart, size_type aCutLength,
+                                             const char* aData,
+                                             size_type aLength,
+                                             const fallible_t&);
+
+  // ReplaceLiteral must ONLY be applied to an actual literal string.
+  // Do not attempt to use it with a regular char* pointer, or with a char
+  // array variable. Use Replace or ReplaceASCII for those.
+  template<int N>
+  void ReplaceLiteral(index_type aCutStart, size_type aCutLength,
+                      const char_type (&aStr)[N])
+  {
+    ReplaceLiteral(aCutStart, aCutLength, aStr, N - 1);
+  }
+
+  void Append(char_type aChar)
+  {
+    Replace(mLength, 0, aChar);
+  }
+  MOZ_MUST_USE bool Append(char_type aChar, const fallible_t& aFallible)
+  {
+    return Replace(mLength, 0, aChar, aFallible);
+  }
+  void Append(const char_type* aData, size_type aLength = size_type(-1))
+  {
+    Replace(mLength, 0, aData, aLength);
+  }
+  MOZ_MUST_USE bool Append(const char_type* aData, size_type aLength,
+                           const fallible_t& aFallible)
+  {
+    return Replace(mLength, 0, aData, aLength, aFallible);
+  }
+
+#if defined(CharT_is_PRUnichar) && defined(MOZ_USE_CHAR16_WRAPPER)
+  void Append(char16ptr_t aData, size_type aLength = size_type(-1))
+  {
+    Append(static_cast<const char16_t*>(aData), aLength);
+  }
+#endif
+
+  void Append(const self_type& aStr)
+  {
+    Replace(mLength, 0, aStr);
+  }
+  MOZ_MUST_USE bool Append(const self_type& aStr, const fallible_t& aFallible)
+  {
+    return Replace(mLength, 0, aStr, aFallible);
+  }
+  void Append(const substring_tuple_type& aTuple)
+  {
+    Replace(mLength, 0, aTuple);
+  }
+
+  void AppendASCII(const char* aData, size_type aLength = size_type(-1))
+  {
+    ReplaceASCII(mLength, 0, aData, aLength);
+  }
+
+  MOZ_MUST_USE bool AppendASCII(const char* aData, const fallible_t& aFallible)
+  {
+    return ReplaceASCII(mLength, 0, aData, size_type(-1), aFallible);
+  }
+
+  MOZ_MUST_USE bool AppendASCII(const char* aData, size_type aLength, const fallible_t& aFallible)
+  {
+    return ReplaceASCII(mLength, 0, aData, aLength, aFallible);
+  }
+
+  /**
+   * Append a formatted string to the current string. Uses the format
+   * codes documented in prprf.h
+   */
+  void AppendPrintf(const char* aFormat, ...);
+  void AppendPrintf(const char* aFormat, va_list aAp);
+  void AppendInt(int32_t aInteger)
+  {
+    AppendPrintf("%d", aInteger);
+  }
+  void AppendInt(int32_t aInteger, int aRadix)
+  {
+    const char* fmt = aRadix == 10 ? "%d" : aRadix == 8 ? "%o" : "%x";
+    AppendPrintf(fmt, aInteger);
+  }
+  void AppendInt(uint32_t aInteger)
+  {
+    AppendPrintf("%u", aInteger);
+  }
+  void AppendInt(uint32_t aInteger, int aRadix)
+  {
+    const char* fmt = aRadix == 10 ? "%u" : aRadix == 8 ? "%o" : "%x";
+    AppendPrintf(fmt, aInteger);
+  }
+  void AppendInt(int64_t aInteger)
+  {
+    AppendPrintf("%lld", aInteger);
+  }
+  void AppendInt(int64_t aInteger, int aRadix)
+  {
+    const char* fmt = aRadix == 10 ? "%lld" : aRadix == 8 ? "%llo" : "%llx";
+    AppendPrintf(fmt, aInteger);
+  }
+  void AppendInt(uint64_t aInteger)
+  {
+    AppendPrintf("%llu", aInteger);
+  }
+  void AppendInt(uint64_t aInteger, int aRadix)
+  {
+    const char* fmt = aRadix == 10 ? "%llu" : aRadix == 8 ? "%llo" : "%llx";
+    AppendPrintf(fmt, aInteger);
+  }
+
+  /**
+   * Append the given float to this string
+   */
+  void NS_FASTCALL AppendFloat(float aFloat);
+  void NS_FASTCALL AppendFloat(double aFloat);
+public:
+
+  // AppendLiteral must ONLY be applied to an actual literal string.
+  // Do not attempt to use it with a regular char* pointer, or with a char
+  // array variable. Use Append or AppendASCII for those.
+  template<int N>
+  void AppendLiteral(const char_type (&aStr)[N])
+  {
+    ReplaceLiteral(mLength, 0, aStr, N - 1);
+  }
+#ifdef CharT_is_PRUnichar
+  template<int N>
+  void AppendLiteral(const char (&aStr)[N])
+  {
+    AppendASCII(aStr, N - 1);
+  }
+
+  template<int N>
+  MOZ_MUST_USE bool AppendLiteral(const char (&aStr)[N], const fallible_t& aFallible)
+  {
+    return AppendASCII(aStr, N - 1, aFallible);
+  }
+#endif
+
+  self_type& operator+=(char_type aChar)
+  {
+    Append(aChar);
+    return *this;
+  }
+  self_type& operator+=(const char_type* aData)
+  {
+    Append(aData);
+    return *this;
+  }
+#if defined(CharT_is_PRUnichar) && defined(MOZ_USE_CHAR16_WRAPPER)
+  self_type& operator+=(char16ptr_t aData)
+  {
+    Append(aData);
+    return *this;
+  }
+#endif
+  self_type& operator+=(const self_type& aStr)
+  {
+    Append(aStr);
+    return *this;
+  }
+  self_type& operator+=(const substring_tuple_type& aTuple)
+  {
+    Append(aTuple);
+    return *this;
+  }
+
+  void Insert(char_type aChar, index_type aPos)
+  {
+    Replace(aPos, 0, aChar);
+  }
+  void Insert(const char_type* aData, index_type aPos,
+              size_type aLength = size_type(-1))
+  {
+    Replace(aPos, 0, aData, aLength);
+  }
+#if defined(CharT_is_PRUnichar) && defined(MOZ_USE_CHAR16_WRAPPER)
+  void Insert(char16ptr_t aData, index_type aPos,
+              size_type aLength = size_type(-1))
+  {
+    Insert(static_cast<const char16_t*>(aData), aPos, aLength);
+  }
+#endif
+  void Insert(const self_type& aStr, index_type aPos)
+  {
+    Replace(aPos, 0, aStr);
+  }
+  void Insert(const substring_tuple_type& aTuple, index_type aPos)
+  {
+    Replace(aPos, 0, aTuple);
+  }
+
+  // InsertLiteral must ONLY be applied to an actual literal string.
+  // Do not attempt to use it with a regular char* pointer, or with a char
+  // array variable. Use Insert for those.
+  template<int N>
+  void InsertLiteral(const char_type (&aStr)[N], index_type aPos)
+  {
+    ReplaceLiteral(aPos, 0, aStr, N - 1);
+  }
+
+  void Cut(index_type aCutStart, size_type aCutLength)
+  {
+    Replace(aCutStart, aCutLength, char_traits::sEmptyBuffer, 0);
+  }
+
+
+  /**
+   * buffer sizing
+   */
+
+  /**
+   * Attempts to set the capacity to the given size in number of
+   * characters, without affecting the length of the string.
+   * There is no need to include room for the null terminator: it is
+   * the job of the string class.
+   * Also ensures that the buffer is mutable.
+   */
+  void NS_FASTCALL SetCapacity(size_type aNewCapacity);
+  MOZ_MUST_USE bool NS_FASTCALL SetCapacity(size_type aNewCapacity,
+                                            const fallible_t&);
+
+  void NS_FASTCALL SetLength(size_type aNewLength);
+  MOZ_MUST_USE bool NS_FASTCALL SetLength(size_type aNewLength,
+                                          const fallible_t&);
+
+  void Truncate(size_type aNewLength = 0)
+  {
+    NS_ASSERTION(aNewLength <= mLength, "Truncate cannot make string longer");
+    SetLength(aNewLength);
+  }
+
+
+  /**
+   * buffer access
+   */
+
+
+  /**
+   * Get a const pointer to the string's internal buffer.  The caller
+   * MUST NOT modify the characters at the returned address.
+   *
+   * @returns The length of the buffer in characters.
+   */
+  inline size_type GetData(const char_type** aData) const
+  {
+    *aData = mData;
+    return mLength;
+  }
+
+  /**
+   * Get a pointer to the string's internal buffer, optionally resizing
+   * the buffer first.  If size_type(-1) is passed for newLen, then the
+   * current length of the string is used.  The caller MAY modify the
+   * characters at the returned address (up to but not exceeding the
+   * length of the string).
+   *
+   * @returns The length of the buffer in characters or 0 if unable to
+   * satisfy the request due to low-memory conditions.
+   */
+  size_type GetMutableData(char_type** aData, size_type aNewLen = size_type(-1))
+  {
+    if (!EnsureMutable(aNewLen)) {
+      AllocFailed(aNewLen == size_type(-1) ? mLength : aNewLen);
+    }
+
+    *aData = mData;
+    return mLength;
+  }
+
+  size_type GetMutableData(char_type** aData, size_type aNewLen, const fallible_t&)
+  {
+    if (!EnsureMutable(aNewLen)) {
+      *aData = nullptr;
+      return 0;
+    }
+
+    *aData = mData;
+    return mLength;
+  }
+
+#if defined(CharT_is_PRUnichar) && defined(MOZ_USE_CHAR16_WRAPPER)
+  size_type GetMutableData(wchar_t** aData, size_type aNewLen = size_type(-1))
+  {
+    return GetMutableData(reinterpret_cast<char16_t**>(aData), aNewLen);
+  }
+
+  size_type GetMutableData(wchar_t** aData, size_type aNewLen,
+                           const fallible_t& aFallible)
+  {
+    return GetMutableData(reinterpret_cast<char16_t**>(aData), aNewLen,
+                          aFallible);
+  }
+#endif
+
+
+  /**
+   * string data is never null, but can be marked void.  if true, the
+   * string will be truncated.  @see nsTSubstring::IsVoid
+   */
+
+  void NS_FASTCALL SetIsVoid(bool);
+
+  /**
+   *  This method is used to remove all occurrences of aChar from this
+   * string.
+   *
+   *  @param  aChar -- char to be stripped
+   *  @param  aOffset -- where in this string to start stripping chars
+   */
+
+  void StripChar(char_type aChar, int32_t aOffset = 0);
+
+  /**
+   *  This method is used to remove all occurrences of aChars from this
+   * string.
+   *
+   *  @param  aChars -- chars to be stripped
+   *  @param  aOffset -- where in this string to start stripping chars
+   */
+
+  void StripChars(const char_type* aChars, uint32_t aOffset = 0);
+
+  /**
+   * If the string uses a shared buffer, this method
+   * clears the pointer without releasing the buffer.
+   */
+  void ForgetSharedBuffer()
+  {
+    if (mFlags & nsSubstring::F_SHARED) {
+      mData = char_traits::sEmptyBuffer;
+      mLength = 0;
+      mFlags = F_TERMINATED;
+    }
+  }
+
+public:
+
+  /**
+   * this is public to support automatic conversion of tuple to string
+   * base type, which helps avoid converting to nsTAString.
+   */
+  MOZ_IMPLICIT nsTSubstring_CharT(const substring_tuple_type& aTuple)
+    : mData(nullptr)
+    , mLength(0)
+    , mFlags(F_NONE)
+  {
+    Assign(aTuple);
+  }
+
+  /**
+   * allows for direct initialization of a nsTSubstring object.
+   *
+   * NOTE: this constructor is declared public _only_ for convenience
+   * inside the string implementation.
+   */
+  // XXXbz or can I just include nscore.h and use NS_BUILD_REFCNT_LOGGING?
+#if defined(DEBUG) || defined(FORCE_BUILD_REFCNT_LOGGING)
+#define XPCOM_STRING_CONSTRUCTOR_OUT_OF_LINE
+  nsTSubstring_CharT(char_type* aData, size_type aLength, uint32_t aFlags);
+#else
+#undef XPCOM_STRING_CONSTRUCTOR_OUT_OF_LINE
+  nsTSubstring_CharT(char_type* aData, size_type aLength, uint32_t aFlags)
+    : mData(aData)
+    , mLength(aLength)
+    , mFlags(aFlags)
+  {
+    MOZ_RELEASE_ASSERT(CheckCapacity(aLength), "String is too large.");
+  }
+#endif /* DEBUG || FORCE_BUILD_REFCNT_LOGGING */
+
+  size_t SizeOfExcludingThisIfUnshared(mozilla::MallocSizeOf aMallocSizeOf)
+  const;
+  size_t SizeOfIncludingThisIfUnshared(mozilla::MallocSizeOf aMallocSizeOf)
+  const;
+
+  /**
+   * WARNING: Only use these functions if you really know what you are
+   * doing, because they can easily lead to double-counting strings.  If
+   * you do use them, please explain clearly in a comment why it's safe
+   * and won't lead to double-counting.
+   */
+  size_t SizeOfExcludingThisEvenIfShared(mozilla::MallocSizeOf aMallocSizeOf)
+  const;
+  size_t SizeOfIncludingThisEvenIfShared(mozilla::MallocSizeOf aMallocSizeOf)
+  const;
+
+  template<class T>
+  void NS_ABORT_OOM(T)
+  {
+    struct never {}; // a compiler-friendly way to do static_assert(false)
+    static_assert(mozilla::IsSame<T, never>::value,
+      "In string classes, use AllocFailed to account for sizeof(char_type). "
+      "Use the global ::NS_ABORT_OOM if you really have a count of bytes.");
+  }
+
+  MOZ_ALWAYS_INLINE void AllocFailed(size_t aLength)
+  {
+    ::NS_ABORT_OOM(aLength * sizeof(char_type));
+  }
+
+protected:
+
+  friend class nsTObsoleteAStringThunk_CharT;
+  friend class nsTSubstringTuple_CharT;
+
+  // XXX GCC 3.4 needs this :-(
+  friend class nsTPromiseFlatString_CharT;
+
+  char_type*  mData;
+  size_type   mLength;
+  uint32_t    mFlags;
+
+  // default initialization
+  nsTSubstring_CharT()
+    : mData(char_traits::sEmptyBuffer)
+    ,  mLength(0)
+    ,  mFlags(F_TERMINATED)
+  {
+  }
+
+  // version of constructor that leaves mData and mLength uninitialized
+  explicit
+  nsTSubstring_CharT(uint32_t aFlags)
+    : mFlags(aFlags)
+  {
+  }
+
+  // copy-constructor, constructs as dependent on given object
+  // (NOTE: this is for internal use only)
+  nsTSubstring_CharT(const self_type& aStr)
+    : mData(aStr.mData)
+    ,  mLength(aStr.mLength)
+    ,  mFlags(aStr.mFlags & (F_TERMINATED | F_VOIDED))
+  {
+  }
+
+  /**
+   * this function releases mData and does not change the value of
+   * any of its member variables.  in other words, this function acts
+   * like a destructor.
+   */
+  void NS_FASTCALL Finalize();
+
+  /**
+   * this function prepares mData to be mutated.
+   *
+   * @param aCapacity    specifies the required capacity of mData
+   * @param aOldData     returns null or the old value of mData
+   * @param aOldFlags    returns 0 or the old value of mFlags
+   *
+   * if mData is already mutable and of sufficient capacity, then this
+   * function will return immediately.  otherwise, it will either resize
+   * mData or allocate a new shared buffer.  if it needs to allocate a
+   * new buffer, then it will return the old buffer and the corresponding
+   * flags.  this allows the caller to decide when to free the old data.
+   *
+   * this function returns false if is unable to allocate sufficient
+   * memory.
+   *
+   * XXX we should expose a way for subclasses to free old_data.
+   */
+  bool NS_FASTCALL MutatePrep(size_type aCapacity,
+                              char_type** aOldData, uint32_t* aOldFlags);
+
+  /**
+   * this function prepares a section of mData to be modified.  if
+   * necessary, this function will reallocate mData and possibly move
+   * existing data to open up the specified section.
+   *
+   * @param aCutStart    specifies the starting offset of the section
+   * @param aCutLength   specifies the length of the section to be replaced
+   * @param aNewLength   specifies the length of the new section
+   *
+   * for example, suppose mData contains the string "abcdef" then
+   *
+   *   ReplacePrep(2, 3, 4);
+   *
+   * would cause mData to look like "ab____f" where the characters
+   * indicated by '_' have an unspecified value and can be freely
+   * modified.  this function will null-terminate mData upon return.
+   *
+   * this function returns false if is unable to allocate sufficient
+   * memory.
+   */
+  MOZ_MUST_USE bool ReplacePrep(index_type aCutStart,
+                                size_type aCutLength,
+                                size_type aNewLength);
+
+  MOZ_MUST_USE bool NS_FASTCALL ReplacePrepInternal(
+    index_type aCutStart,
+    size_type aCutLength,
+    size_type aNewFragLength,
+    size_type aNewTotalLength);
+
+  /**
+   * returns the number of writable storage units starting at mData.
+   * the value does not include space for the null-terminator character.
+   *
+   * NOTE: this function returns 0 if mData is immutable (or the buffer
+   *       is 0-sized).
+   */
+  size_type NS_FASTCALL Capacity() const;
+
+  /**
+   * this helper function can be called prior to directly manipulating
+   * the contents of mData.  see, for example, BeginWriting.
+   */
+  MOZ_MUST_USE bool NS_FASTCALL EnsureMutable(
+    size_type aNewLen = size_type(-1));
+
+  /**
+   * returns true if this string overlaps with the given string fragment.
+   */
+  bool IsDependentOn(const char_type* aStart, const char_type* aEnd) const
+  {
+    /**
+     * if it _isn't_ the case that one fragment starts after the other ends,
+     * or ends before the other starts, then, they conflict:
+     *
+     *   !(f2.begin >= f1.aEnd || f2.aEnd <= f1.begin)
+     *
+     * Simplified, that gives us:
+     */
+    return (aStart < (mData + mLength) && aEnd > mData);
+  }
+
+  /**
+   * Checks if the given capacity is valid for this string type.
+   */
+  static MOZ_MUST_USE bool CheckCapacity(size_type aCapacity) {
+    if (aCapacity > kMaxCapacity) {
+      // Also assert for |aCapacity| equal to |size_type(-1)|, since we used to
+      // use that value to flag immutability.
+      NS_ASSERTION(aCapacity != size_type(-1), "Bogus capacity");
+      return false;
+    }
+
+    return true;
+  }
+
+  /**
+   * this helper function stores the specified dataFlags in mFlags
+   */
+  void SetDataFlags(uint32_t aDataFlags)
+  {
+    NS_ASSERTION((aDataFlags & 0xFFFF0000) == 0, "bad flags");
+    mFlags = aDataFlags | (mFlags & 0xFFFF0000);
+  }
+
+  void NS_FASTCALL ReplaceLiteral(index_type aCutStart, size_type aCutLength,
+                                  const char_type* aData, size_type aLength);
+
+  static int AppendFunc(void* aArg, const char* aStr, uint32_t aLen);
+
+  static const size_type kMaxCapacity;
+public:
+
+  // NOTE: this method is declared public _only_ for convenience for
+  // callers who don't have access to the original nsLiteralString_CharT.
+  void NS_FASTCALL AssignLiteral(const char_type* aData, size_type aLength);
+
+  // mFlags is a bitwise combination of the following flags.  the meaning
+  // and interpretation of these flags is an implementation detail.
+  //
+  // NOTE: these flags are declared public _only_ for convenience inside
+  // the string implementation.
+
+  enum
+  {
+    F_NONE         = 0,       // no flags
+
+    // data flags are in the lower 16-bits
+    F_TERMINATED   = 1 << 0,  // IsTerminated returns true
+    F_VOIDED       = 1 << 1,  // IsVoid returns true
+    F_SHARED       = 1 << 2,  // mData points to a heap-allocated, shared buffer
+    F_OWNED        = 1 << 3,  // mData points to a heap-allocated, raw buffer
+    F_FIXED        = 1 << 4,  // mData points to a fixed-size writable, dependent buffer
+    F_LITERAL      = 1 << 5,  // mData points to a string literal; F_TERMINATED will also be set
+
+    // class flags are in the upper 16-bits
+    F_CLASS_FIXED  = 1 << 16   // indicates that |this| is of type nsTFixedString
+  };
+
+  //
+  // Some terminology:
+  //
+  //   "dependent buffer"    A dependent buffer is one that the string class
+  //                         does not own.  The string class relies on some
+  //                         external code to ensure the lifetime of the
+  //                         dependent buffer.
+  //
+  //   "shared buffer"       A shared buffer is one that the string class
+  //                         allocates.  When it allocates a shared string
+  //                         buffer, it allocates some additional space at
+  //                         the beginning of the buffer for additional
+  //                         fields, including a reference count and a
+  //                         buffer length.  See nsStringHeader.
+  //
+  //   "adopted buffer"      An adopted buffer is a raw string buffer
+  //                         allocated on the heap (using moz_xmalloc)
+  //                         of which the string class subsumes ownership.
+  //
+  // Some comments about the string flags:
+  //
+  //   F_SHARED, F_OWNED, and F_FIXED are all mutually exlusive.  They
+  //   indicate the allocation type of mData.  If none of these flags
+  //   are set, then the string buffer is dependent.
+  //
+  //   F_SHARED, F_OWNED, or F_FIXED imply F_TERMINATED.  This is because
+  //   the string classes always allocate null-terminated buffers, and
+  //   non-terminated substrings are always dependent.
+  //
+  //   F_VOIDED implies F_TERMINATED, and moreover it implies that mData
+  //   points to char_traits::sEmptyBuffer.  Therefore, F_VOIDED is
+  //   mutually exclusive with F_SHARED, F_OWNED, and F_FIXED.
+  //
+};
+
+int NS_FASTCALL
+Compare(const nsTSubstring_CharT::base_string_type& aLhs,
+        const nsTSubstring_CharT::base_string_type& aRhs,
+        const nsTStringComparator_CharT& = nsTDefaultStringComparator_CharT());
+
+
+inline bool
+operator!=(const nsTSubstring_CharT::base_string_type& aLhs,
+           const nsTSubstring_CharT::base_string_type& aRhs)
+{
+  return !aLhs.Equals(aRhs);
+}
+
+inline bool
+operator!=(const nsTSubstring_CharT::base_string_type& aLhs,
+           const nsTSubstring_CharT::char_type* aRhs)
+{
+  return !aLhs.Equals(aRhs);
+}
+
+inline bool
+operator<(const nsTSubstring_CharT::base_string_type& aLhs,
+          const nsTSubstring_CharT::base_string_type& aRhs)
+{
+  return Compare(aLhs, aRhs) < 0;
+}
+
+inline bool
+operator<=(const nsTSubstring_CharT::base_string_type& aLhs,
+           const nsTSubstring_CharT::base_string_type& aRhs)
+{
+  return Compare(aLhs, aRhs) <= 0;
+}
+
+inline bool
+operator==(const nsTSubstring_CharT::base_string_type& aLhs,
+           const nsTSubstring_CharT::base_string_type& aRhs)
+{
+  return aLhs.Equals(aRhs);
+}
+
+inline bool
+operator==(const nsTSubstring_CharT::base_string_type& aLhs,
+           const nsTSubstring_CharT::char_type* aRhs)
+{
+  return aLhs.Equals(aRhs);
+}
+
+
+inline bool
+operator>=(const nsTSubstring_CharT::base_string_type& aLhs,
+           const nsTSubstring_CharT::base_string_type& aRhs)
+{
+  return Compare(aLhs, aRhs) >= 0;
+}
+
+inline bool
+operator>(const nsTSubstring_CharT::base_string_type& aLhs,
+          const nsTSubstring_CharT::base_string_type& aRhs)
+{
+  return Compare(aLhs, aRhs) > 0;
+}
diff --git a/xpcom/string/nsTSubstringTuple.cpp b/xpcom/string/nsTSubstringTuple.cpp
new file mode 100644
index 000000000..2a84a9a4e
--- /dev/null
+++ b/xpcom/string/nsTSubstringTuple.cpp
@@ -0,0 +1,96 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/CheckedInt.h"
+
+/**
+ * computes the aggregate string length
+ */
+
+nsTSubstringTuple_CharT::size_type
+nsTSubstringTuple_CharT::Length() const
+{
+  mozilla::CheckedInt<size_type> len;
+  if (mHead) {
+    len = mHead->Length();
+  } else {
+    len = TO_SUBSTRING(mFragA).Length();
+  }
+
+  len += TO_SUBSTRING(mFragB).Length();
+  MOZ_RELEASE_ASSERT(len.isValid(), "Substring tuple length is invalid");
+  return len.value();
+}
+
+
+/**
+ * writes the aggregate string to the given buffer. aBufLen is assumed
+ * to be equal to or greater than the value returned by the Length()
+ * method.  the string written to |aBuf| is not null-terminated.
+ */
+
+void
+nsTSubstringTuple_CharT::WriteTo(char_type* aBuf, uint32_t aBufLen) const
+{
+  const substring_type& b = TO_SUBSTRING(mFragB);
+
+  MOZ_RELEASE_ASSERT(aBufLen >= b.Length(), "buffer too small");
+  uint32_t headLen = aBufLen - b.Length();
+  if (mHead) {
+    mHead->WriteTo(aBuf, headLen);
+  } else {
+    const substring_type& a = TO_SUBSTRING(mFragA);
+
+    MOZ_RELEASE_ASSERT(a.Length() == headLen, "buffer incorrectly sized");
+    char_traits::copy(aBuf, a.Data(), a.Length());
+  }
+
+  char_traits::copy(aBuf + headLen, b.Data(), b.Length());
+
+#if 0
+  // we need to write out data into |aBuf|, ending at |aBuf + aBufLen|. So our
+  // data needs to precede |aBuf + aBufLen| exactly. We trust that the buffer
+  // was properly sized!
+
+  const substring_type& b = TO_SUBSTRING(mFragB);
+
+  NS_ASSERTION(aBufLen >= b.Length(), "buffer is too small");
+  char_traits::copy(aBuf + aBufLen - b.Length(), b.Data(), b.Length());
+
+  aBufLen -= b.Length();
+
+  if (mHead) {
+    mHead->WriteTo(aBuf, aBufLen);
+  } else {
+    const substring_type& a = TO_SUBSTRING(mFragA);
+    NS_ASSERTION(aBufLen == a.Length(), "buffer is too small");
+    char_traits::copy(aBuf, a.Data(), a.Length());
+  }
+#endif
+}
+
+
+/**
+ * returns true if this tuple is dependent on (i.e., overlapping with)
+ * the given char sequence.
+ */
+
+bool
+nsTSubstringTuple_CharT::IsDependentOn(const char_type* aStart,
+                                       const char_type* aEnd) const
+{
+  // we aStart with the right-most fragment since it is faster to check.
+
+  if (TO_SUBSTRING(mFragB).IsDependentOn(aStart, aEnd)) {
+    return true;
+  }
+
+  if (mHead) {
+    return mHead->IsDependentOn(aStart, aEnd);
+  }
+
+  return TO_SUBSTRING(mFragA).IsDependentOn(aStart, aEnd);
+}
diff --git a/xpcom/string/nsTSubstringTuple.h b/xpcom/string/nsTSubstringTuple.h
new file mode 100644
index 000000000..5d24e2159
--- /dev/null
+++ b/xpcom/string/nsTSubstringTuple.h
@@ -0,0 +1,84 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+// IWYU pragma: private, include "nsString.h"
+
+/**
+ * nsTSubstringTuple_CharT
+ *
+ * Represents a tuple of string fragments.  Built as a recursive binary tree.
+ * It is used to implement the concatenation of two or more string objects.
+ *
+ * NOTE: This class is a private implementation detail and should never be
+ * referenced outside the string code.
+ */
+class nsTSubstringTuple_CharT
+{
+public:
+
+  typedef CharT                      char_type;
+  typedef nsCharTraits<char_type>    char_traits;
+
+  typedef nsTSubstringTuple_CharT    self_type;
+  typedef nsTSubstring_CharT         substring_type;
+  typedef nsTSubstring_CharT         base_string_type;
+  typedef uint32_t                   size_type;
+
+public:
+
+  nsTSubstringTuple_CharT(const base_string_type* aStrA,
+                          const base_string_type* aStrB)
+    : mHead(nullptr)
+    , mFragA(aStrA)
+    , mFragB(aStrB)
+  {
+  }
+
+  nsTSubstringTuple_CharT(const self_type& aHead,
+                          const base_string_type* aStrB)
+    : mHead(&aHead)
+    , mFragA(nullptr) // this fragment is ignored when aHead != nullptr
+    , mFragB(aStrB)
+  {
+  }
+
+  /**
+   * computes the aggregate string length
+   */
+  size_type Length() const;
+
+  /**
+   * writes the aggregate string to the given buffer.  bufLen is assumed
+   * to be equal to or greater than the value returned by the Length()
+   * method.  the string written to |buf| is not null-terminated.
+   */
+  void WriteTo(char_type* aBuf, uint32_t aBufLen) const;
+
+  /**
+   * returns true if this tuple is dependent on (i.e., overlapping with)
+   * the given char sequence.
+   */
+  bool IsDependentOn(const char_type* aStart, const char_type* aEnd) const;
+
+private:
+
+  const self_type*        mHead;
+  const base_string_type* mFragA;
+  const base_string_type* mFragB;
+};
+
+inline const nsTSubstringTuple_CharT
+operator+(const nsTSubstringTuple_CharT::base_string_type& aStrA,
+          const nsTSubstringTuple_CharT::base_string_type& aStrB)
+{
+  return nsTSubstringTuple_CharT(&aStrA, &aStrB);
+}
+
+inline const nsTSubstringTuple_CharT
+operator+(const nsTSubstringTuple_CharT& aHead,
+          const nsTSubstringTuple_CharT::base_string_type& aStrB)
+{
+  return nsTSubstringTuple_CharT(aHead, &aStrB);
+}
diff --git a/xpcom/string/nsUTF8Utils.h b/xpcom/string/nsUTF8Utils.h
new file mode 100644
index 000000000..9f38fa555
--- /dev/null
+++ b/xpcom/string/nsUTF8Utils.h
@@ -0,0 +1,742 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef nsUTF8Utils_h_
+#define nsUTF8Utils_h_
+
+// This file may be used in two ways: if MOZILLA_INTERNAL_API is defined, this
+// file will provide signatures for the Mozilla abstract string types. It will
+// use XPCOM assertion/debugging macros, etc.
+
+#include "nscore.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/SSE.h"
+#include "mozilla/TypeTraits.h"
+
+#include "nsCharTraits.h"
+
+class UTF8traits
+{
+public:
+  static bool isASCII(char aChar)
+  {
+    return (aChar & 0x80) == 0x00;
+  }
+  static bool isInSeq(char aChar)
+  {
+    return (aChar & 0xC0) == 0x80;
+  }
+  static bool is2byte(char aChar)
+  {
+    return (aChar & 0xE0) == 0xC0;
+  }
+  static bool is3byte(char aChar)
+  {
+    return (aChar & 0xF0) == 0xE0;
+  }
+  static bool is4byte(char aChar)
+  {
+    return (aChar & 0xF8) == 0xF0;
+  }
+  static bool is5byte(char aChar)
+  {
+    return (aChar & 0xFC) == 0xF8;
+  }
+  static bool is6byte(char aChar)
+  {
+    return (aChar & 0xFE) == 0xFC;
+  }
+};
+
+/**
+ * Extract the next UCS-4 character from the buffer and return it.  The
+ * pointer passed in is advanced to the start of the next character in the
+ * buffer.  If non-null, the parameters err and overlong are filled in to
+ * indicate that the character was represented by an overlong sequence, or
+ * that an error occurred.
+ */
+
+class UTF8CharEnumerator
+{
+public:
+  static uint32_t NextChar(const char** aBuffer, const char* aEnd, bool* aErr)
+  {
+    NS_ASSERTION(aBuffer && *aBuffer, "null buffer!");
+
+    const char* p = *aBuffer;
+    *aErr = false;
+
+    if (p >= aEnd) {
+      *aErr = true;
+
+      return 0;
+    }
+
+    char c = *p++;
+
+    if (UTF8traits::isASCII(c)) {
+      *aBuffer = p;
+      return c;
+    }
+
+    uint32_t ucs4;
+    uint32_t minUcs4;
+    int32_t state = 0;
+
+    if (!CalcState(c, ucs4, minUcs4, state)) {
+      NS_ERROR("Not a UTF-8 string. This code should only be used for converting from known UTF-8 strings.");
+      *aErr = true;
+
+      return 0;
+    }
+
+    while (state--) {
+      if (p == aEnd) {
+        *aErr = true;
+
+        return 0;
+      }
+
+      c = *p++;
+
+      if (!AddByte(c, state, ucs4)) {
+        *aErr = true;
+
+        return 0;
+      }
+    }
+
+    if (ucs4 < minUcs4) {
+      // Overlong sequence
+      ucs4 = UCS2_REPLACEMENT_CHAR;
+    } else if (ucs4 >= 0xD800 &&
+               (ucs4 <= 0xDFFF || ucs4 >= UCS_END)) {
+      // Surrogates and code points outside the Unicode range.
+      ucs4 = UCS2_REPLACEMENT_CHAR;
+    }
+
+    *aBuffer = p;
+    return ucs4;
+  }
+
+private:
+  static bool CalcState(char aChar, uint32_t& aUcs4, uint32_t& aMinUcs4,
+                        int32_t& aState)
+  {
+    if (UTF8traits::is2byte(aChar)) {
+      aUcs4 = (uint32_t(aChar) << 6) & 0x000007C0L;
+      aState = 1;
+      aMinUcs4 = 0x00000080;
+    } else if (UTF8traits::is3byte(aChar)) {
+      aUcs4 = (uint32_t(aChar) << 12) & 0x0000F000L;
+      aState = 2;
+      aMinUcs4 = 0x00000800;
+    } else if (UTF8traits::is4byte(aChar)) {
+      aUcs4 = (uint32_t(aChar) << 18) & 0x001F0000L;
+      aState = 3;
+      aMinUcs4 = 0x00010000;
+    } else if (UTF8traits::is5byte(aChar)) {
+      aUcs4 = (uint32_t(aChar) << 24) & 0x03000000L;
+      aState = 4;
+      aMinUcs4 = 0x00200000;
+    } else if (UTF8traits::is6byte(aChar)) {
+      aUcs4 = (uint32_t(aChar) << 30) & 0x40000000L;
+      aState = 5;
+      aMinUcs4 = 0x04000000;
+    } else {
+      return false;
+    }
+
+    return true;
+  }
+
+  static bool AddByte(char aChar, int32_t aState, uint32_t& aUcs4)
+  {
+    if (UTF8traits::isInSeq(aChar)) {
+      int32_t shift = aState * 6;
+      aUcs4 |= (uint32_t(aChar) & 0x3F) << shift;
+      return true;
+    }
+
+    return false;
+  }
+};
+
+
+/**
+ * Extract the next UCS-4 character from the buffer and return it.  The
+ * pointer passed in is advanced to the start of the next character in the
+ * buffer.  If non-null, the err parameter is filled in if an error occurs.
+ *
+ * If an error occurs that causes UCS2_REPLACEMENT_CHAR to be returned, then
+ * the buffer will be updated to move only a single UCS-2 character.
+ *
+ * Any other error returns 0 and does not move the buffer position.
+ */
+
+
+class UTF16CharEnumerator
+{
+public:
+  static uint32_t NextChar(const char16_t** aBuffer, const char16_t* aEnd,
+                           bool* aErr = nullptr)
+  {
+    NS_ASSERTION(aBuffer && *aBuffer, "null buffer!");
+
+    const char16_t* p = *aBuffer;
+
+    if (p >= aEnd) {
+      NS_ERROR("No input to work with");
+      if (aErr) {
+        *aErr = true;
+      }
+
+      return 0;
+    }
+
+    char16_t c = *p++;
+
+    if (!IS_SURROGATE(c)) { // U+0000 - U+D7FF,U+E000 - U+FFFF
+      if (aErr) {
+        *aErr = false;
+      }
+      *aBuffer = p;
+      return c;
+    } else if (NS_IS_HIGH_SURROGATE(c)) { // U+D800 - U+DBFF
+      if (p == aEnd) {
+        // Found a high surrogate at the end of the buffer. Flag this
+        // as an error and return the Unicode replacement
+        // character 0xFFFD.
+
+        NS_WARNING("Unexpected end of buffer after high surrogate");
+
+        if (aErr) {
+          *aErr = true;
+        }
+        *aBuffer = p;
+        return 0xFFFD;
+      }
+
+      // D800- DBFF - High Surrogate
+      char16_t h = c;
+
+      c = *p++;
+
+      if (NS_IS_LOW_SURROGATE(c)) {
+        // DC00- DFFF - Low Surrogate
+        // N = (H - D800) *400 + 10000 + (L - DC00)
+        uint32_t ucs4 = SURROGATE_TO_UCS4(h, c);
+        if (aErr) {
+          *aErr = false;
+        }
+        *aBuffer = p;
+        return ucs4;
+      } else {
+        // Found a high surrogate followed by something other than
+        // a low surrogate. Flag this as an error and return the
+        // Unicode replacement character 0xFFFD.  Note that the
+        // pointer to the next character points to the second 16-bit
+        // value, not beyond it, as per Unicode 5.0.0 Chapter 3 C10,
+        // only the first code unit of an illegal sequence must be
+        // treated as an illegally terminated code unit sequence
+        // (also Chapter 3 D91, "isolated [not paired and ill-formed]
+        // UTF-16 code units in the range D800..DFFF are ill-formed").
+        NS_WARNING("got a High Surrogate but no low surrogate");
+
+        if (aErr) {
+          *aErr = true;
+        }
+        *aBuffer = p - 1;
+        return 0xFFFD;
+      }
+    } else { // U+DC00 - U+DFFF
+      // DC00- DFFF - Low Surrogate
+
+      // Found a low surrogate w/o a preceding high surrogate. Flag
+      // this as an error and return the Unicode replacement
+      // character 0xFFFD.
+
+      NS_WARNING("got a low Surrogate but no high surrogate");
+      if (aErr) {
+        *aErr = true;
+      }
+      *aBuffer = p;
+      return 0xFFFD;
+    }
+
+    MOZ_ASSERT_UNREACHABLE("Impossible UCS-2 character value.");
+  }
+};
+
+
+/**
+ * A character sink (see |copy_string| in nsAlgorithm.h) for converting
+ * UTF-8 to UTF-16
+ */
+class ConvertUTF8toUTF16
+{
+public:
+  typedef char value_type;
+  typedef char16_t buffer_type;
+
+  explicit ConvertUTF8toUTF16(buffer_type* aBuffer)
+    : mStart(aBuffer), mBuffer(aBuffer), mErrorEncountered(false)
+  {
+  }
+
+  size_t Length() const
+  {
+    return mBuffer - mStart;
+  }
+
+  bool ErrorEncountered() const
+  {
+    return mErrorEncountered;
+  }
+
+  void write(const value_type* aStart, uint32_t aN)
+  {
+    if (mErrorEncountered) {
+      return;
+    }
+
+    // algorithm assumes utf8 units won't
+    // be spread across fragments
+    const value_type* p = aStart;
+    const value_type* end = aStart + aN;
+    buffer_type* out = mBuffer;
+    for (; p != end /* && *p */;) {
+      bool err;
+      uint32_t ucs4 = UTF8CharEnumerator::NextChar(&p, end, &err);
+
+      if (err) {
+        mErrorEncountered = true;
+        mBuffer = out;
+        return;
+      }
+
+      if (ucs4 >= PLANE1_BASE) {
+        *out++ = (buffer_type)H_SURROGATE(ucs4);
+        *out++ = (buffer_type)L_SURROGATE(ucs4);
+      } else {
+        *out++ = ucs4;
+      }
+    }
+    mBuffer = out;
+  }
+
+  void write_terminator()
+  {
+    *mBuffer = buffer_type(0);
+  }
+
+private:
+  buffer_type* const mStart;
+  buffer_type* mBuffer;
+  bool mErrorEncountered;
+};
+
+/**
+ * A character sink (see |copy_string| in nsAlgorithm.h) for computing
+ * the length of the UTF-16 string equivalent to a UTF-8 string.
+ */
+class CalculateUTF8Length
+{
+public:
+  typedef char value_type;
+
+  CalculateUTF8Length()
+    : mLength(0), mErrorEncountered(false)
+  {
+  }
+
+  size_t Length() const
+  {
+    return mLength;
+  }
+
+  void write(const value_type* aStart, uint32_t aN)
+  {
+    // ignore any further requests
+    if (mErrorEncountered) {
+      return;
+    }
+
+    // algorithm assumes utf8 units won't
+    // be spread across fragments
+    const value_type* p = aStart;
+    const value_type* end = aStart + aN;
+    for (; p < end /* && *p */; ++mLength) {
+      if (UTF8traits::isASCII(*p)) {
+        p += 1;
+      } else if (UTF8traits::is2byte(*p)) {
+        p += 2;
+      } else if (UTF8traits::is3byte(*p)) {
+        p += 3;
+      } else if (UTF8traits::is4byte(*p)) {
+        // Because a UTF-8 sequence of 4 bytes represents a codepoint
+        // greater than 0xFFFF, it will become a surrogate pair in the
+        // UTF-16 string, so add 1 more to mLength.
+        // This doesn't happen with is5byte and is6byte because they
+        // are illegal UTF-8 sequences (greater than 0x10FFFF) so get
+        // converted to a single replacement character.
+
+        // However, there is one case when a 4 byte UTF-8 sequence will
+        // only generate 2 UTF-16 bytes. If we have a properly encoded
+        // sequence, but with an invalid value (too small or too big),
+        // that will result in a replacement character being written
+        // This replacement character is encoded as just 1 single
+        // UTF-16 character, which is 2 bytes.
+
+        // The below code therefore only adds 1 to mLength if the UTF8
+        // data will produce a decoded character which is greater than
+        // or equal to 0x010000 and less than 0x0110000.
+
+        // A 4byte UTF8 character is encoded as
+        // 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
+        // Bit 1-3 on the first byte, and bit 5-6 on the second byte,
+        // map to bit 17-21 in the final result. If these bits are
+        // between 0x01 and 0x11, that means that the final result is
+        // between 0x010000 and 0x110000. The below code reads these
+        // bits out and assigns them to c, but shifted up 4 bits to
+        // avoid having to shift twice.
+
+        // It doesn't matter what to do in the case where p + 4 > end
+        // since no UTF16 characters will be written in that case by
+        // ConvertUTF8toUTF16. Likewise it doesn't matter what we do if
+        // any of the surrogate bits are wrong since no UTF16
+        // characters will be written in that case either.
+
+        if (p + 4 <= end) {
+          uint32_t c = ((uint32_t)(p[0] & 0x07)) << 6 |
+                       ((uint32_t)(p[1] & 0x30));
+          if (c >= 0x010 && c < 0x110) {
+            ++mLength;
+          }
+        }
+
+        p += 4;
+      } else if (UTF8traits::is5byte(*p)) {
+        p += 5;
+      } else if (UTF8traits::is6byte(*p)) {
+        p += 6;
+      } else { // error
+        ++mLength; // to account for the decrement below
+        break;
+      }
+    }
+    if (p != end) {
+      NS_ERROR("Not a UTF-8 string. This code should only be used for converting from known UTF-8 strings.");
+      --mLength; // The last multi-byte char wasn't complete, discard it.
+      mErrorEncountered = true;
+    }
+  }
+
+private:
+  size_t mLength;
+  bool mErrorEncountered;
+};
+
+/**
+ * A character sink (see |copy_string| in nsAlgorithm.h) for
+ * converting UTF-16 to UTF-8. Treats invalid UTF-16 data as 0xFFFD
+ * (0xEFBFBD in UTF-8).
+ */
+class ConvertUTF16toUTF8
+{
+public:
+  typedef char16_t value_type;
+  typedef char buffer_type;
+
+  // The error handling here is more lenient than that in
+  // |ConvertUTF8toUTF16|, but it's that way for backwards
+  // compatibility.
+
+  explicit ConvertUTF16toUTF8(buffer_type* aBuffer)
+    : mStart(aBuffer), mBuffer(aBuffer)
+  {
+  }
+
+  size_t Size() const
+  {
+    return mBuffer - mStart;
+  }
+
+  void write(const value_type* aStart, uint32_t aN)
+  {
+    buffer_type* out = mBuffer; // gcc isn't smart enough to do this!
+
+    for (const value_type* p = aStart, *end = aStart + aN; p < end; ++p) {
+      value_type c = *p;
+      if (!(c & 0xFF80)) { // U+0000 - U+007F
+        *out++ = (char)c;
+      } else if (!(c & 0xF800)) { // U+0100 - U+07FF
+        *out++ = 0xC0 | (char)(c >> 6);
+        *out++ = 0x80 | (char)(0x003F & c);
+      } else if (!IS_SURROGATE(c)) { // U+0800 - U+D7FF,U+E000 - U+FFFF
+        *out++ = 0xE0 | (char)(c >> 12);
+        *out++ = 0x80 | (char)(0x003F & (c >> 6));
+        *out++ = 0x80 | (char)(0x003F & c);
+      } else if (NS_IS_HIGH_SURROGATE(c)) { // U+D800 - U+DBFF
+        // D800- DBFF - High Surrogate
+        value_type h = c;
+
+        ++p;
+        if (p == end) {
+          // Treat broken characters as the Unicode
+          // replacement character 0xFFFD (0xEFBFBD in
+          // UTF-8)
+          *out++ = '\xEF';
+          *out++ = '\xBF';
+          *out++ = '\xBD';
+
+          NS_WARNING("String ending in half a surrogate pair!");
+
+          break;
+        }
+        c = *p;
+
+        if (NS_IS_LOW_SURROGATE(c)) {
+          // DC00- DFFF - Low Surrogate
+          // N = (H - D800) *400 + 10000 + ( L - DC00 )
+          uint32_t ucs4 = SURROGATE_TO_UCS4(h, c);
+
+          // 0001 0000-001F FFFF
+          *out++ = 0xF0 | (char)(ucs4 >> 18);
+          *out++ = 0x80 | (char)(0x003F & (ucs4 >> 12));
+          *out++ = 0x80 | (char)(0x003F & (ucs4 >> 6));
+          *out++ = 0x80 | (char)(0x003F & ucs4);
+        } else {
+          // Treat broken characters as the Unicode
+          // replacement character 0xFFFD (0xEFBFBD in
+          // UTF-8)
+          *out++ = '\xEF';
+          *out++ = '\xBF';
+          *out++ = '\xBD';
+
+          // The pointer to the next character points to the second
+          // 16-bit value, not beyond it, as per Unicode 5.0.0
+          // Chapter 3 C10, only the first code unit of an illegal
+          // sequence must be treated as an illegally terminated
+          // code unit sequence (also Chapter 3 D91, "isolated [not
+          // paired and ill-formed] UTF-16 code units in the range
+          // D800..DFFF are ill-formed").
+          p--;
+
+          NS_WARNING("got a High Surrogate but no low surrogate");
+        }
+      } else { // U+DC00 - U+DFFF
+        // Treat broken characters as the Unicode replacement
+        // character 0xFFFD (0xEFBFBD in UTF-8)
+        *out++ = '\xEF';
+        *out++ = '\xBF';
+        *out++ = '\xBD';
+
+        // DC00- DFFF - Low Surrogate
+        NS_WARNING("got a low Surrogate but no high surrogate");
+      }
+    }
+
+    mBuffer = out;
+  }
+
+  void write_terminator()
+  {
+    *mBuffer = buffer_type(0);
+  }
+
+private:
+  buffer_type* const mStart;
+  buffer_type* mBuffer;
+};
+
+/**
+ * A character sink (see |copy_string| in nsAlgorithm.h) for computing
+ * the number of bytes a UTF-16 would occupy in UTF-8. Treats invalid
+ * UTF-16 data as 0xFFFD (0xEFBFBD in UTF-8).
+ */
+class CalculateUTF8Size
+{
+public:
+  typedef char16_t value_type;
+
+  CalculateUTF8Size()
+    : mSize(0)
+  {
+  }
+
+  size_t Size() const
+  {
+    return mSize;
+  }
+
+  void write(const value_type* aStart, uint32_t aN)
+  {
+    // Assume UCS2 surrogate pairs won't be spread across fragments.
+    for (const value_type* p = aStart, *end = aStart + aN; p < end; ++p) {
+      value_type c = *p;
+      if (!(c & 0xFF80)) { // U+0000 - U+007F
+        mSize += 1;
+      } else if (!(c & 0xF800)) { // U+0100 - U+07FF
+        mSize += 2;
+      } else if (0xD800 != (0xF800 & c)) { // U+0800 - U+D7FF,U+E000 - U+FFFF
+        mSize += 3;
+      } else if (0xD800 == (0xFC00 & c)) { // U+D800 - U+DBFF
+        ++p;
+        if (p == end) {
+          // Treat broken characters as the Unicode
+          // replacement character 0xFFFD (0xEFBFBD in
+          // UTF-8)
+          mSize += 3;
+
+          NS_WARNING("String ending in half a surrogate pair!");
+
+          break;
+        }
+        c = *p;
+
+        if (0xDC00 == (0xFC00 & c)) {
+          mSize += 4;
+        } else {
+          // Treat broken characters as the Unicode
+          // replacement character 0xFFFD (0xEFBFBD in
+          // UTF-8)
+          mSize += 3;
+
+          // The next code unit is the second 16-bit value, not
+          // the one beyond it, as per Unicode 5.0.0 Chapter 3 C10,
+          // only the first code unit of an illegal sequence must
+          // be treated as an illegally terminated code unit
+          // sequence (also Chapter 3 D91, "isolated [not paired and
+          // ill-formed] UTF-16 code units in the range D800..DFFF
+          // are ill-formed").
+          p--;
+
+          NS_WARNING("got a high Surrogate but no low surrogate");
+        }
+      } else { // U+DC00 - U+DFFF
+        // Treat broken characters as the Unicode replacement
+        // character 0xFFFD (0xEFBFBD in UTF-8)
+        mSize += 3;
+
+        NS_WARNING("got a low Surrogate but no high surrogate");
+      }
+    }
+  }
+
+private:
+  size_t mSize;
+};
+
+#ifdef MOZILLA_INTERNAL_API
+/**
+ * A character sink that performs a |reinterpret_cast|-style conversion
+ * from char to char16_t.
+ */
+class LossyConvertEncoding8to16
+{
+public:
+  typedef char value_type;
+  typedef char input_type;
+  typedef char16_t output_type;
+
+public:
+  explicit LossyConvertEncoding8to16(char16_t* aDestination) :
+    mDestination(aDestination)
+  {
+  }
+
+  void
+  write(const char* aSource, uint32_t aSourceLength)
+  {
+#ifdef MOZILLA_MAY_SUPPORT_SSE2
+    if (mozilla::supports_sse2()) {
+      write_sse2(aSource, aSourceLength);
+      return;
+    }
+#endif
+    const char* done_writing = aSource + aSourceLength;
+    while (aSource < done_writing) {
+      *mDestination++ = (char16_t)(unsigned char)(*aSource++);
+    }
+  }
+
+  void
+  write_sse2(const char* aSource, uint32_t aSourceLength);
+
+  void
+  write_terminator()
+  {
+    *mDestination = (char16_t)(0);
+  }
+
+private:
+  char16_t* mDestination;
+};
+
+/**
+ * A character sink that performs a |reinterpret_cast|-style conversion
+ * from char16_t to char.
+ */
+class LossyConvertEncoding16to8
+{
+public:
+  typedef char16_t value_type;
+  typedef char16_t input_type;
+  typedef char output_type;
+
+  explicit LossyConvertEncoding16to8(char* aDestination)
+    : mDestination(aDestination)
+  {
+  }
+
+  void
+  write(const char16_t* aSource, uint32_t aSourceLength)
+  {
+#ifdef MOZILLA_MAY_SUPPORT_SSE2
+    if (mozilla::supports_sse2()) {
+      write_sse2(aSource, aSourceLength);
+      return;
+    }
+#endif
+    const char16_t* done_writing = aSource + aSourceLength;
+    while (aSource < done_writing) {
+      *mDestination++ = (char)(*aSource++);
+    }
+  }
+
+#ifdef MOZILLA_MAY_SUPPORT_SSE2
+  void
+  write_sse2(const char16_t* aSource, uint32_t aSourceLength);
+#endif
+
+  void
+  write_terminator()
+  {
+    *mDestination = '\0';
+  }
+
+private:
+  char* mDestination;
+};
+#endif // MOZILLA_INTERNAL_API
+
+
+template<typename Char, typename UnsignedT>
+inline UnsignedT
+RewindToPriorUTF8Codepoint(const Char* utf8Chars, UnsignedT index)
+{
+  static_assert(mozilla::IsSame<Char, char>::value ||
+                mozilla::IsSame<Char, unsigned char>::value ||
+                mozilla::IsSame<Char, signed char>::value,
+                "UTF-8 data must be in 8-bit units");
+  static_assert(mozilla::IsUnsigned<UnsignedT>::value, "index type must be unsigned");
+  while (index > 0 && (utf8Chars[index] & 0xC0) == 0x80)
+    --index;
+
+  return index;
+}
+
+#endif /* !defined(nsUTF8Utils_h_) */
diff --git a/xpcom/string/nsUTF8UtilsSSE2.cpp b/xpcom/string/nsUTF8UtilsSSE2.cpp
new file mode 100644
index 000000000..daf2c56b0
--- /dev/null
+++ b/xpcom/string/nsUTF8UtilsSSE2.cpp
@@ -0,0 +1,105 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nscore.h"
+#include "nsAlgorithm.h"
+#include <emmintrin.h>
+#include <nsUTF8Utils.h>
+
+void
+LossyConvertEncoding16to8::write_sse2(const char16_t* aSource,
+                                      uint32_t aSourceLength)
+{
+  char* dest = mDestination;
+
+  // Align source to a 16-byte boundary.
+  uint32_t i = 0;
+  uint32_t alignLen =
+    XPCOM_MIN<uint32_t>(aSourceLength,
+                        uint32_t(-NS_PTR_TO_INT32(aSource) & 0xf) / sizeof(char16_t));
+  for (; i < alignLen; ++i) {
+    dest[i] = static_cast<unsigned char>(aSource[i]);
+  }
+
+  // Walk 64 bytes (four XMM registers) at a time.
+  __m128i vectmask = _mm_set1_epi16(0x00ff);
+  for (; aSourceLength - i > 31; i += 32) {
+    __m128i source1 = _mm_load_si128(reinterpret_cast<const __m128i*>(aSource + i));
+    source1 = _mm_and_si128(source1, vectmask);
+
+    __m128i source2 = _mm_load_si128(reinterpret_cast<const __m128i*>(aSource + i + 8));
+    source2 = _mm_and_si128(source2, vectmask);
+
+    __m128i source3 = _mm_load_si128(reinterpret_cast<const __m128i*>(aSource + i + 16));
+    source3 = _mm_and_si128(source3, vectmask);
+
+    __m128i source4 = _mm_load_si128(reinterpret_cast<const __m128i*>(aSource + i + 24));
+    source4 = _mm_and_si128(source4, vectmask);
+
+
+    // Pack the source data.  SSE2 views this as a saturating uint16_t to
+    // uint8_t conversion, but since we masked off the high-order byte of every
+    // uint16_t, we're really just grabbing the low-order bytes of source1 and
+    // source2.
+    __m128i packed1 = _mm_packus_epi16(source1, source2);
+    __m128i packed2 = _mm_packus_epi16(source3, source4);
+
+    // This store needs to be unaligned since there's no guarantee that the
+    // alignment we did above for the source will align the destination.
+    _mm_storeu_si128(reinterpret_cast<__m128i*>(dest + i),      packed1);
+    _mm_storeu_si128(reinterpret_cast<__m128i*>(dest + i + 16), packed2);
+  }
+
+  // Finish up the rest.
+  for (; i < aSourceLength; ++i) {
+    dest[i] = static_cast<unsigned char>(aSource[i]);
+  }
+
+  mDestination += i;
+}
+
+void
+LossyConvertEncoding8to16::write_sse2(const char* aSource,
+                                      uint32_t aSourceLength)
+{
+  char16_t* dest = mDestination;
+
+  // Align source to a 16-byte boundary.  We choose to align source rather than
+  // dest because we'd rather have our loads than our stores be fast. You have
+  // to wait for a load to complete, but you can keep on moving after issuing a
+  // store.
+  uint32_t i = 0;
+  uint32_t alignLen = XPCOM_MIN(aSourceLength,
+                                uint32_t(-NS_PTR_TO_INT32(aSource) & 0xf));
+  for (; i < alignLen; ++i) {
+    dest[i] = static_cast<unsigned char>(aSource[i]);
+  }
+
+  // Walk 32 bytes (two XMM registers) at a time.
+  for (; aSourceLength - i > 31; i += 32) {
+    __m128i source1 = _mm_load_si128(reinterpret_cast<const __m128i*>(aSource + i));
+    __m128i source2 = _mm_load_si128(reinterpret_cast<const __m128i*>(aSource + i + 16));
+
+    // Interleave 0s in with the bytes of source to create lo and hi.
+    __m128i lo1 = _mm_unpacklo_epi8(source1, _mm_setzero_si128());
+    __m128i hi1 = _mm_unpackhi_epi8(source1, _mm_setzero_si128());
+    __m128i lo2 = _mm_unpacklo_epi8(source2, _mm_setzero_si128());
+    __m128i hi2 = _mm_unpackhi_epi8(source2, _mm_setzero_si128());
+
+    // store lo and hi into dest.
+    _mm_storeu_si128(reinterpret_cast<__m128i*>(dest + i),      lo1);
+    _mm_storeu_si128(reinterpret_cast<__m128i*>(dest + i + 8),  hi1);
+    _mm_storeu_si128(reinterpret_cast<__m128i*>(dest + i + 16), lo2);
+    _mm_storeu_si128(reinterpret_cast<__m128i*>(dest + i + 24), hi2);
+  }
+
+  // Finish up whatever's left.
+  for (; i < aSourceLength; ++i) {
+    dest[i] = static_cast<unsigned char>(aSource[i]);
+  }
+
+  mDestination += i;
+}
diff --git a/xpcom/string/nsXPCOMStrings.h b/xpcom/string/nsXPCOMStrings.h
new file mode 100644
index 000000000..493e092d6
--- /dev/null
+++ b/xpcom/string/nsXPCOMStrings.h
@@ -0,0 +1,748 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsXPCOMStrings_h__
+#define nsXPCOMStrings_h__
+
+#include <string.h>
+#include "nscore.h"
+#include <limits>
+
+/**
+ * nsXPCOMStrings.h
+ *
+ * This file describes a minimal API for working with XPCOM's abstract
+ * string classes.  It divorces the consumer from having any run-time
+ * dependency on the implementation details of the abstract string types.
+ */
+
+#include "nscore.h"
+
+/* The base string types */
+class nsAString;
+class nsACString;
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * nsStringContainer
+ *
+ * This is an opaque data type that is large enough to hold the canonical
+ * implementation of nsAString.  The binary structure of this class is an
+ * implementation detail.
+ *
+ * The string data stored in a string container is always single fragment
+ * and may be null-terminated depending on how it is initialized.
+ *
+ * Typically, string containers are allocated on the stack for temporary
+ * use.  However, they can also be malloc'd if necessary.  In either case,
+ * a string container is not useful until it has been initialized with a
+ * call to NS_StringContainerInit.  The following example shows how to use
+ * a string container to call a function that takes a |nsAString &| out-param.
+ *
+ *   nsresult GetBlah(nsAString &aBlah);
+ *
+ *   nsresult MyCode()
+ *   {
+ *     nsresult rv;
+ *
+ *     nsStringContainer sc;
+ *     rv = NS_StringContainerInit(sc);
+ *     if (NS_FAILED(rv))
+ *       return rv;
+ *
+ *     rv = GetBlah(sc);
+ *     if (NS_SUCCEEDED(rv))
+ *     {
+ *       const char16_t *data;
+ *       NS_StringGetData(sc, &data);
+ *       //
+ *       // |data| now points to the result of the GetBlah function
+ *       //
+ *     }
+ *
+ *     NS_StringContainerFinish(sc);
+ *     return rv;
+ *   }
+ *
+ * The following example show how to use a string container to pass a string
+ * parameter to a function taking a |const nsAString &| in-param.
+ *
+ *   nsresult SetBlah(const nsAString &aBlah);
+ *
+ *   nsresult MyCode()
+ *   {
+ *     nsresult rv;
+ *
+ *     nsStringContainer sc;
+ *     rv = NS_StringContainerInit(sc);
+ *     if (NS_FAILED(rv))
+ *       return rv;
+ *
+ *     const char16_t kData[] = {'x','y','z','\0'};
+ *     rv = NS_StringSetData(sc, kData, sizeof(kData)/2 - 1);
+ *     if (NS_SUCCEEDED(rv))
+ *       rv = SetBlah(sc);
+ *
+ *     NS_StringContainerFinish(sc);
+ *     return rv;
+ *   }
+ */
+class nsStringContainer;
+
+
+/**
+ * This struct is never used directly. It is designed to have the same
+ * size as nsString. It can be stack and heap allocated and the internal
+ * functions cast it to nsString.
+ * While this practice is a strict aliasing violation, it doesn't seem to
+ * cause problems since the the struct is only accessed via the casts to
+ * nsString.
+ * We use protected instead of private to avoid compiler warnings about
+ * the members being unused.
+ */
+struct nsStringContainer_base
+{
+protected:
+  void* d1;
+  uint32_t d2;
+  uint32_t d3;
+};
+
+/**
+ * Flags that may be OR'd together to pass to NS_StringContainerInit2:
+ */
+enum
+{
+  /* Data passed into NS_StringContainerInit2 is not copied; instead, the
+   * string references the passed in data pointer directly.  The caller must
+   * ensure that the data is valid for the lifetime of the string container.
+   * This flag should not be combined with NS_STRING_CONTAINER_INIT_ADOPT. */
+  NS_STRING_CONTAINER_INIT_DEPEND    = (1 << 1),
+
+  /* Data passed into NS_StringContainerInit2 is not copied; instead, the
+   * string takes ownership over the data pointer.  The caller must have
+   * allocated the data array using the XPCOM memory allocator (nsMemory).
+   * This flag should not be combined with NS_STRING_CONTAINER_INIT_DEPEND. */
+  NS_STRING_CONTAINER_INIT_ADOPT     = (1 << 2),
+
+  /* Data passed into NS_StringContainerInit2 is a substring that is not
+   * null-terminated. */
+  NS_STRING_CONTAINER_INIT_SUBSTRING = (1 << 3)
+};
+
+/**
+ * NS_StringContainerInit
+ *
+ * @param aContainer    string container reference
+ * @return              NS_OK if string container successfully initialized
+ *
+ * This function may allocate additional memory for aContainer.  When
+ * aContainer is no longer needed, NS_StringContainerFinish should be called.
+ */
+XPCOM_API(nsresult) NS_StringContainerInit(nsStringContainer& aContainer);
+
+/**
+ * NS_StringContainerInit2
+ *
+ * @param aContainer    string container reference
+ * @param aData         character buffer (may be null)
+ * @param aDataLength   number of characters stored at aData (may pass
+ *                      UINT32_MAX if aData is null-terminated)
+ * @param aFlags        flags affecting how the string container is
+ *                      initialized.  this parameter is ignored when aData
+ *                      is null.  otherwise, if this parameter is 0, then
+ *                      aData is copied into the string.
+ *
+ * This function resembles NS_StringContainerInit but provides further
+ * options that permit more efficient memory usage.  When aContainer is
+ * no longer needed, NS_StringContainerFinish should be called.
+ *
+ * NOTE: NS_StringContainerInit2(container, nullptr, 0, 0) is equivalent to
+ * NS_StringContainerInit(container).
+ */
+XPCOM_API(nsresult) NS_StringContainerInit2(nsStringContainer& aContainer,
+                                            const char16_t* aData = nullptr,
+                                            uint32_t aDataLength = UINT32_MAX,
+                                            uint32_t aFlags = 0);
+
+/**
+ * NS_StringContainerFinish
+ *
+ * @param aContainer    string container reference
+ *
+ * This function frees any memory owned by aContainer.
+ */
+XPCOM_API(void) NS_StringContainerFinish(nsStringContainer& aContainer);
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * NS_StringGetData
+ *
+ * This function returns a const character pointer to the string's internal
+ * buffer, the length of the string, and a boolean value indicating whether
+ * or not the buffer is null-terminated.
+ *
+ * @param aStr          abstract string reference
+ * @param aData         out param that will hold the address of aStr's
+ *                      internal buffer
+ * @param aTerminated   if non-null, this out param will be set to indicate
+ *                      whether or not aStr's internal buffer is null-
+ *                      terminated
+ * @return              length of aStr's internal buffer
+ */
+XPCOM_API(uint32_t) NS_StringGetData(const nsAString& aStr,
+                                     const char16_t** aData,
+                                     bool* aTerminated = nullptr);
+
+/**
+ * NS_StringGetMutableData
+ *
+ * This function provides mutable access to a string's internal buffer.  It
+ * returns a pointer to an array of characters that may be modified.  The
+ * returned pointer remains valid until the string object is passed to some
+ * other string function.
+ *
+ * Optionally, this function may be used to resize the string's internal
+ * buffer.  The aDataLength parameter specifies the requested length of the
+ * string's internal buffer.  By passing some value other than UINT32_MAX,
+ * the caller can request that the buffer be resized to the specified number of
+ * characters before returning.  The caller is not responsible for writing a
+ * null-terminator.
+ *
+ * @param aStr          abstract string reference
+ * @param aDataLength   number of characters to resize the string's internal
+ *                      buffer to or UINT32_MAX if no resizing is needed
+ * @param aData         out param that upon return holds the address of aStr's
+ *                      internal buffer or null if the function failed
+ * @return              number of characters or zero if the function failed
+ *
+ * This function does not necessarily null-terminate aStr after resizing its
+ * internal buffer.  The behavior depends on the implementation of the abstract
+ * string, aStr.  If aStr is a reference to a nsStringContainer, then its data
+ * will be null-terminated by this function.
+ */
+XPCOM_API(uint32_t) NS_StringGetMutableData(nsAString& aStr,
+                                            uint32_t aDataLength,
+                                            char16_t** aData);
+
+/**
+ * NS_StringCloneData
+ *
+ * This function returns a null-terminated copy of the string's
+ * internal buffer.
+ *
+ * @param aStr          abstract string reference
+ * @return              null-terminated copy of the string's internal buffer
+ *                      (it must be free'd using using free)
+ */
+XPCOM_API(char16_t*) NS_StringCloneData(const nsAString& aStr);
+
+/**
+ * NS_StringSetData
+ *
+ * This function copies aData into aStr.
+ *
+ * @param aStr          abstract string reference
+ * @param aData         character buffer
+ * @param aDataLength   number of characters to copy from source string (pass
+ *                      UINT32_MAX to copy until end of aData, designated by
+ *                      a null character)
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aStr after copying data
+ * from aData.  The behavior depends on the implementation of the abstract
+ * string, aStr.  If aStr is a reference to a nsStringContainer, then its data
+ * will be null-terminated by this function.
+ */
+XPCOM_API(nsresult) NS_StringSetData(nsAString& aStr, const char16_t* aData,
+                                     uint32_t aDataLength = UINT32_MAX);
+
+/**
+ * NS_StringSetDataRange
+ *
+ * This function copies aData into a section of aStr.  As a result it can be
+ * used to insert new characters into the string.
+ *
+ * @param aStr          abstract string reference
+ * @param aCutOffset    starting index where the string's existing data
+ *                      is to be overwritten (pass UINT32_MAX to cause
+ *                      aData to be appended to the end of aStr, in which
+ *                      case the value of aCutLength is ignored).
+ * @param aCutLength    number of characters to overwrite starting at
+ *                      aCutOffset (pass UINT32_MAX to overwrite until the
+ *                      end of aStr).
+ * @param aData         character buffer (pass null to cause this function
+ *                      to simply remove the "cut" range)
+ * @param aDataLength   number of characters to copy from source string (pass
+ *                      UINT32_MAX to copy until end of aData, designated by
+ *                      a null character)
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aStr after copying data
+ * from aData.  The behavior depends on the implementation of the abstract
+ * string, aStr.  If aStr is a reference to a nsStringContainer, then its data
+ * will be null-terminated by this function.
+ */
+XPCOM_API(nsresult) NS_StringSetDataRange(nsAString& aStr,
+                                          uint32_t aCutOffset, uint32_t aCutLength,
+                                          const char16_t* aData,
+                                          uint32_t aDataLength = UINT32_MAX);
+
+/**
+ * NS_StringCopy
+ *
+ * This function makes aDestStr have the same value as aSrcStr.  It is
+ * provided as an optimization.
+ *
+ * @param aDestStr      abstract string reference to be modified
+ * @param aSrcStr       abstract string reference containing source string
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aDestStr after copying
+ * data from aSrcStr.  The behavior depends on the implementation of the
+ * abstract string, aDestStr.  If aDestStr is a reference to a
+ * nsStringContainer, then its data will be null-terminated by this function.
+ */
+XPCOM_API(nsresult) NS_StringCopy(nsAString& aDestStr,
+                                  const nsAString& aSrcStr);
+
+/**
+ * NS_StringAppendData
+ *
+ * This function appends data to the existing value of aStr.
+ *
+ * @param aStr          abstract string reference to be modified
+ * @param aData         character buffer
+ * @param aDataLength   number of characters to append (pass UINT32_MAX to
+ *                      append until a null-character is encountered)
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aStr upon completion.
+ * The behavior depends on the implementation of the abstract string, aStr.
+ * If aStr is a reference to a nsStringContainer, then its data will be null-
+ * terminated by this function.
+ */
+inline NS_HIDDEN_(nsresult)
+NS_StringAppendData(nsAString& aStr, const char16_t* aData,
+                    uint32_t aDataLength = UINT32_MAX)
+{
+  return NS_StringSetDataRange(aStr, UINT32_MAX, 0, aData, aDataLength);
+}
+
+/**
+ * NS_StringInsertData
+ *
+ * This function inserts data into the existing value of aStr at the specified
+ * offset.
+ *
+ * @param aStr          abstract string reference to be modified
+ * @param aOffset       specifies where in the string to insert aData
+ * @param aData         character buffer
+ * @param aDataLength   number of characters to append (pass UINT32_MAX to
+ *                      append until a null-character is encountered)
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aStr upon completion.
+ * The behavior depends on the implementation of the abstract string, aStr.
+ * If aStr is a reference to a nsStringContainer, then its data will be null-
+ * terminated by this function.
+ */
+inline NS_HIDDEN_(nsresult)
+NS_StringInsertData(nsAString& aStr, uint32_t aOffset, const char16_t* aData,
+                    uint32_t aDataLength = UINT32_MAX)
+{
+  return NS_StringSetDataRange(aStr, aOffset, 0, aData, aDataLength);
+}
+
+/**
+ * NS_StringCutData
+ *
+ * This function shortens the existing value of aStr, by removing characters
+ * at the specified offset.
+ *
+ * @param aStr          abstract string reference to be modified
+ * @param aCutOffset    specifies where in the string to insert aData
+ * @param aCutLength    number of characters to remove
+ * @return              NS_OK if function succeeded
+ */
+inline NS_HIDDEN_(nsresult)
+NS_StringCutData(nsAString& aStr, uint32_t aCutOffset, uint32_t aCutLength)
+{
+  return NS_StringSetDataRange(aStr, aCutOffset, aCutLength, nullptr, 0);
+}
+
+/**
+ * NS_StringSetIsVoid
+ *
+ * This function marks a string as being a "void string".  Any data in the
+ * string will be lost.
+ */
+XPCOM_API(void) NS_StringSetIsVoid(nsAString& aStr, const bool aIsVoid);
+
+/**
+ * NS_StringGetIsVoid
+ *
+ * This function provides a way to test if a string is a "void string", as
+ * marked by NS_StringSetIsVoid.
+ */
+XPCOM_API(bool) NS_StringGetIsVoid(const nsAString& aStr);
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * nsCStringContainer
+ *
+ * This is an opaque data type that is large enough to hold the canonical
+ * implementation of nsACString.  The binary structure of this class is an
+ * implementation detail.
+ *
+ * The string data stored in a string container is always single fragment
+ * and may be null-terminated depending on how it is initialized.
+ *
+ * @see nsStringContainer for use cases and further documentation.
+ */
+class nsCStringContainer;
+
+/**
+ * Flags that may be OR'd together to pass to NS_StringContainerInit2:
+ */
+enum
+{
+  /* Data passed into NS_CStringContainerInit2 is not copied; instead, the
+   * string references the passed in data pointer directly.  The caller must
+   * ensure that the data is valid for the lifetime of the string container.
+   * This flag should not be combined with NS_CSTRING_CONTAINER_INIT_ADOPT. */
+  NS_CSTRING_CONTAINER_INIT_DEPEND    = (1 << 1),
+
+  /* Data passed into NS_CStringContainerInit2 is not copied; instead, the
+   * string takes ownership over the data pointer.  The caller must have
+   * allocated the data array using the XPCOM memory allocator (nsMemory).
+   * This flag should not be combined with NS_CSTRING_CONTAINER_INIT_DEPEND. */
+  NS_CSTRING_CONTAINER_INIT_ADOPT     = (1 << 2),
+
+  /* Data passed into NS_CStringContainerInit2 is a substring that is not
+   * null-terminated. */
+  NS_CSTRING_CONTAINER_INIT_SUBSTRING = (1 << 3)
+};
+
+/**
+ * NS_CStringContainerInit
+ *
+ * @param aContainer    string container reference
+ * @return              NS_OK if string container successfully initialized
+ *
+ * This function may allocate additional memory for aContainer.  When
+ * aContainer is no longer needed, NS_CStringContainerFinish should be called.
+ */
+XPCOM_API(nsresult) NS_CStringContainerInit(nsCStringContainer& aContainer);
+
+/**
+ * NS_CStringContainerInit2
+ *
+ * @param aContainer    string container reference
+ * @param aData         character buffer (may be null)
+ * @param aDataLength   number of characters stored at aData (may pass
+ *                      UINT32_MAX if aData is null-terminated)
+ * @param aFlags        flags affecting how the string container is
+ *                      initialized.  this parameter is ignored when aData
+ *                      is null.  otherwise, if this parameter is 0, then
+ *                      aData is copied into the string.
+ *
+ * This function resembles NS_CStringContainerInit but provides further
+ * options that permit more efficient memory usage.  When aContainer is
+ * no longer needed, NS_CStringContainerFinish should be called.
+ *
+ * NOTE: NS_CStringContainerInit2(container, nullptr, 0, 0) is equivalent to
+ * NS_CStringContainerInit(container).
+ */
+XPCOM_API(nsresult) NS_CStringContainerInit2(nsCStringContainer& aContainer,
+                                             const char* aData = nullptr,
+                                             uint32_t aDataLength = UINT32_MAX,
+                                             uint32_t aFlags = 0);
+
+/**
+ * NS_CStringContainerFinish
+ *
+ * @param aContainer    string container reference
+ *
+ * This function frees any memory owned by aContainer.
+ */
+XPCOM_API(void) NS_CStringContainerFinish(nsCStringContainer& aContainer);
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * NS_CStringGetData
+ *
+ * This function returns a const character pointer to the string's internal
+ * buffer, the length of the string, and a boolean value indicating whether
+ * or not the buffer is null-terminated.
+ *
+ * @param aStr          abstract string reference
+ * @param aData         out param that will hold the address of aStr's
+ *                      internal buffer
+ * @param aTerminated   if non-null, this out param will be set to indicate
+ *                      whether or not aStr's internal buffer is null-
+ *                      terminated
+ * @return              length of aStr's internal buffer
+ */
+XPCOM_API(uint32_t) NS_CStringGetData(const nsACString& aStr,
+                                      const char** aData,
+                                      bool* aTerminated = nullptr);
+
+/**
+ * NS_CStringGetMutableData
+ *
+ * This function provides mutable access to a string's internal buffer.  It
+ * returns a pointer to an array of characters that may be modified.  The
+ * returned pointer remains valid until the string object is passed to some
+ * other string function.
+ *
+ * Optionally, this function may be used to resize the string's internal
+ * buffer.  The aDataLength parameter specifies the requested length of the
+ * string's internal buffer.  By passing some value other than UINT32_MAX,
+ * the caller can request that the buffer be resized to the specified number of
+ * characters before returning.  The caller is not responsible for writing a
+ * null-terminator.
+ *
+ * @param aStr          abstract string reference
+ * @param aDataLength   number of characters to resize the string's internal
+ *                      buffer to or UINT32_MAX if no resizing is needed
+ * @param aData         out param that upon return holds the address of aStr's
+ *                      internal buffer or null if the function failed
+ * @return              number of characters or zero if the function failed
+ *
+ * This function does not necessarily null-terminate aStr after resizing its
+ * internal buffer.  The behavior depends on the implementation of the abstract
+ * string, aStr.  If aStr is a reference to a nsStringContainer, then its data
+ * will be null-terminated by this function.
+ */
+XPCOM_API(uint32_t) NS_CStringGetMutableData(nsACString& aStr,
+                                             uint32_t aDataLength,
+                                             char** aData);
+
+/**
+ * NS_CStringCloneData
+ *
+ * This function returns a null-terminated copy of the string's
+ * internal buffer.
+ *
+ * @param aStr          abstract string reference
+ * @return              null-terminated copy of the string's internal buffer
+ *                      (it must be free'd using using free)
+ */
+XPCOM_API(char*) NS_CStringCloneData(const nsACString& aStr);
+
+/**
+ * NS_CStringSetData
+ *
+ * This function copies aData into aStr.
+ *
+ * @param aStr          abstract string reference
+ * @param aData         character buffer
+ * @param aDataLength   number of characters to copy from source string (pass
+ *                      UINT32_MAX to copy until end of aData, designated by
+ *                      a null character)
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aStr after copying data
+ * from aData.  The behavior depends on the implementation of the abstract
+ * string, aStr.  If aStr is a reference to a nsStringContainer, then its data
+ * will be null-terminated by this function.
+ */
+XPCOM_API(nsresult) NS_CStringSetData(nsACString& aStr, const char* aData,
+                                      uint32_t aDataLength = UINT32_MAX);
+
+/**
+ * NS_CStringSetDataRange
+ *
+ * This function copies aData into a section of aStr.  As a result it can be
+ * used to insert new characters into the string.
+ *
+ * @param aStr          abstract string reference
+ * @param aCutOffset    starting index where the string's existing data
+ *                      is to be overwritten (pass UINT32_MAX to cause
+ *                      aData to be appended to the end of aStr, in which
+ *                      case the value of aCutLength is ignored).
+ * @param aCutLength    number of characters to overwrite starting at
+ *                      aCutOffset (pass UINT32_MAX to overwrite until the
+ *                      end of aStr).
+ * @param aData         character buffer (pass null to cause this function
+ *                      to simply remove the "cut" range)
+ * @param aDataLength   number of characters to copy from source string (pass
+ *                      UINT32_MAX to copy until end of aData, designated by
+ *                      a null character)
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aStr after copying data
+ * from aData.  The behavior depends on the implementation of the abstract
+ * string, aStr.  If aStr is a reference to a nsStringContainer, then its data
+ * will be null-terminated by this function.
+ */
+XPCOM_API(nsresult) NS_CStringSetDataRange(nsACString& aStr,
+                                           uint32_t aCutOffset,
+                                           uint32_t aCutLength,
+                                           const char* aData,
+                                           uint32_t aDataLength = UINT32_MAX);
+
+/**
+ * NS_CStringCopy
+ *
+ * This function makes aDestStr have the same value as aSrcStr.  It is
+ * provided as an optimization.
+ *
+ * @param aDestStr      abstract string reference to be modified
+ * @param aSrcStr       abstract string reference containing source string
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aDestStr after copying
+ * data from aSrcStr.  The behavior depends on the implementation of the
+ * abstract string, aDestStr.  If aDestStr is a reference to a
+ * nsStringContainer, then its data will be null-terminated by this function.
+ */
+XPCOM_API(nsresult) NS_CStringCopy(nsACString& aDestStr,
+                                   const nsACString& aSrcStr);
+
+/**
+ * NS_CStringAppendData
+ *
+ * This function appends data to the existing value of aStr.
+ *
+ * @param aStr          abstract string reference to be modified
+ * @param aData         character buffer
+ * @param aDataLength   number of characters to append (pass UINT32_MAX to
+ *                      append until a null-character is encountered)
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aStr upon completion.
+ * The behavior depends on the implementation of the abstract string, aStr.
+ * If aStr is a reference to a nsStringContainer, then its data will be null-
+ * terminated by this function.
+ */
+inline NS_HIDDEN_(nsresult)
+NS_CStringAppendData(nsACString& aStr, const char* aData,
+                     uint32_t aDataLength = UINT32_MAX)
+{
+  return NS_CStringSetDataRange(aStr, UINT32_MAX, 0, aData, aDataLength);
+}
+
+/**
+ * NS_CStringInsertData
+ *
+ * This function inserts data into the existing value of aStr at the specified
+ * offset.
+ *
+ * @param aStr          abstract string reference to be modified
+ * @param aOffset       specifies where in the string to insert aData
+ * @param aData         character buffer
+ * @param aDataLength   number of characters to append (pass UINT32_MAX to
+ *                      append until a null-character is encountered)
+ * @return              NS_OK if function succeeded
+ *
+ * This function does not necessarily null-terminate aStr upon completion.
+ * The behavior depends on the implementation of the abstract string, aStr.
+ * If aStr is a reference to a nsStringContainer, then its data will be null-
+ * terminated by this function.
+ */
+inline NS_HIDDEN_(nsresult)
+NS_CStringInsertData(nsACString& aStr, uint32_t aOffset, const char* aData,
+                     uint32_t aDataLength = UINT32_MAX)
+{
+  return NS_CStringSetDataRange(aStr, aOffset, 0, aData, aDataLength);
+}
+
+/**
+ * NS_CStringCutData
+ *
+ * This function shortens the existing value of aStr, by removing characters
+ * at the specified offset.
+ *
+ * @param aStr          abstract string reference to be modified
+ * @param aCutOffset    specifies where in the string to insert aData
+ * @param aCutLength    number of characters to remove
+ * @return              NS_OK if function succeeded
+ */
+inline NS_HIDDEN_(nsresult)
+NS_CStringCutData(nsACString& aStr, uint32_t aCutOffset, uint32_t aCutLength)
+{
+  return NS_CStringSetDataRange(aStr, aCutOffset, aCutLength, nullptr, 0);
+}
+
+/**
+ * NS_CStringSetIsVoid
+ *
+ * This function marks a string as being a "void string".  Any data in the
+ * string will be lost.
+ */
+XPCOM_API(void) NS_CStringSetIsVoid(nsACString& aStr, const bool aIsVoid);
+
+/**
+ * NS_CStringGetIsVoid
+ *
+ * This function provides a way to test if a string is a "void string", as
+ * marked by NS_CStringSetIsVoid.
+ */
+XPCOM_API(bool) NS_CStringGetIsVoid(const nsACString& aStr);
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Encodings that can be used with the following conversion routines.
+ */
+enum nsCStringEncoding
+{
+  /* Conversion between ASCII and UTF-16 assumes that all bytes in the source
+   * string are 7-bit ASCII and can be inflated to UTF-16 by inserting null
+   * bytes.  Reverse conversion is done by truncating every other byte.  The
+   * conversion may result in loss and/or corruption of information if the
+   * strings do not strictly contain ASCII data. */
+  NS_CSTRING_ENCODING_ASCII = 0,
+
+  /* Conversion between UTF-8 and UTF-16 is non-lossy. */
+  NS_CSTRING_ENCODING_UTF8 = 1,
+
+  /* Conversion from UTF-16 to the native filesystem charset may result in a
+   * loss of information.  No attempt is made to protect against data loss in
+   * this case.  The native filesystem charset applies to strings passed to
+   * the "Native" method variants on nsIFile. */
+  NS_CSTRING_ENCODING_NATIVE_FILESYSTEM = 2
+};
+
+/**
+ * NS_CStringToUTF16
+ *
+ * This function converts the characters in a nsACString to an array of UTF-16
+ * characters, in the platform endianness.  The result is stored in a nsAString
+ * object.
+ *
+ * @param aSource       abstract string reference containing source string
+ * @param aSrcEncoding  character encoding of the source string
+ * @param aDest         abstract string reference to hold the result
+ */
+XPCOM_API(nsresult) NS_CStringToUTF16(const nsACString& aSource,
+                                      nsCStringEncoding aSrcEncoding,
+                                      nsAString& aDest);
+
+/**
+ * NS_UTF16ToCString
+ *
+ * This function converts the UTF-16 characters in a nsAString to a single-byte
+ * encoding.  The result is stored in a nsACString object.  In some cases this
+ * conversion may be lossy.  In such cases, the conversion may succeed with a
+ * return code indicating loss of information.  The exact behavior is not
+ * specified at this time.
+ *
+ * @param aSource       abstract string reference containing source string
+ * @param aDestEncoding character encoding of the resulting string
+ * @param aDest         abstract string reference to hold the result
+ */
+XPCOM_API(nsresult) NS_UTF16ToCString(const nsAString& aSource,
+                                      nsCStringEncoding aDestEncoding,
+                                      nsACString& aDest);
+
+#endif // nsXPCOMStrings_h__
diff --git a/xpcom/string/nsXPIDLString.h b/xpcom/string/nsXPIDLString.h
new file mode 100644
index 000000000..f5821cdb0
--- /dev/null
+++ b/xpcom/string/nsXPIDLString.h
@@ -0,0 +1,12 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsXPIDLString_h___
+#define nsXPIDLString_h___
+
+#include "nsString.h"
+
+#endif /* !defined(nsXPIDLString_h___) */
diff --git a/xpcom/string/string-template-def-char.h b/xpcom/string/string-template-def-char.h
new file mode 100644
index 000000000..82f70d0fb
--- /dev/null
+++ b/xpcom/string/string-template-def-char.h
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+// IWYU pragma: private, include "nsString.h"
+
+#define CharT                               char
+#define CharT_is_char                       1
+#define nsTAString_IncompatibleCharT        nsAString
+#define nsTString_CharT                     nsCString
+#define nsTFixedString_CharT                nsFixedCString
+#define nsTAutoString_CharT                 nsAutoCString
+#define nsTSubstring_CharT                  nsACString
+#define nsTSubstringTuple_CharT             nsCSubstringTuple
+#define nsTStringComparator_CharT           nsCStringComparator
+#define nsTDefaultStringComparator_CharT    nsDefaultCStringComparator
+#define nsTDependentString_CharT            nsDependentCString
+#define nsTDependentSubstring_CharT         nsDependentCSubstring
+#define nsTLiteralString_CharT              nsLiteralCString
+#define nsTXPIDLString_CharT                nsXPIDLCString
+#define nsTGetterCopies_CharT               nsCGetterCopies
+#define nsTAdoptingString_CharT             nsAdoptingCString
+#define nsTPromiseFlatString_CharT          nsPromiseFlatCString
+#define TPromiseFlatString_CharT            PromiseFlatCString
diff --git a/xpcom/string/string-template-def-unichar.h b/xpcom/string/string-template-def-unichar.h
new file mode 100644
index 000000000..a21e16d09
--- /dev/null
+++ b/xpcom/string/string-template-def-unichar.h
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+// IWYU pragma: private, include "nsString.h"
+
+#define CharT                               char16_t
+#define CharT_is_PRUnichar                  1
+#define nsTAString_IncompatibleCharT        nsACString
+#define nsTString_CharT                     nsString
+#define nsTFixedString_CharT                nsFixedString
+#define nsTAutoString_CharT                 nsAutoString
+#define nsTSubstring_CharT                  nsAString
+#define nsTSubstringTuple_CharT             nsSubstringTuple
+#define nsTStringComparator_CharT           nsStringComparator
+#define nsTDefaultStringComparator_CharT    nsDefaultStringComparator
+#define nsTDependentString_CharT            nsDependentString
+#define nsTDependentSubstring_CharT         nsDependentSubstring
+#define nsTLiteralString_CharT              nsLiteralString
+#define nsTXPIDLString_CharT                nsXPIDLString
+#define nsTGetterCopies_CharT               nsGetterCopies
+#define nsTAdoptingString_CharT             nsAdoptingString
+#define nsTPromiseFlatString_CharT          nsPromiseFlatString
+#define TPromiseFlatString_CharT            PromiseFlatString
diff --git a/xpcom/string/string-template-undef.h b/xpcom/string/string-template-undef.h
new file mode 100644
index 000000000..d62cd2278
--- /dev/null
+++ b/xpcom/string/string-template-undef.h
@@ -0,0 +1,26 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+// IWYU pragma: private, include "nsString.h"
+
+#undef CharT
+#undef CharT_is_PRUnichar
+#undef CharT_is_char
+#undef nsTAString_IncompatibleCharT
+#undef nsTString_CharT
+#undef nsTFixedString_CharT
+#undef nsTAutoString_CharT
+#undef nsTSubstring_CharT
+#undef nsTSubstringTuple_CharT
+#undef nsTStringComparator_CharT
+#undef nsTDefaultStringComparator_CharT
+#undef nsTDependentString_CharT
+#undef nsTDependentSubstring_CharT
+#undef nsTLiteralString_CharT
+#undef nsTXPIDLString_CharT
+#undef nsTGetterCopies_CharT
+#undef nsTAdoptingString_CharT
+#undef nsTPromiseFlatString_CharT
+#undef TPromiseFlatString_CharT
diff --git a/xpcom/system/moz.build b/xpcom/system/moz.build
new file mode 100644
index 000000000..8a4f88efe
--- /dev/null
+++ b/xpcom/system/moz.build
@@ -0,0 +1,26 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+XPIDL_SOURCES += [
+    'nsIBlocklistService.idl',
+    'nsIDeviceSensors.idl',
+    'nsIGConfService.idl',
+    'nsIGeolocationProvider.idl',
+    'nsIGIOService.idl',
+    'nsIGSettingsService.idl',
+    'nsIHapticFeedback.idl',
+    'nsIPackageKitService.idl',
+    'nsIPlatformInfo.idl',
+    'nsIXULAppInfo.idl',
+    'nsIXULRuntime.idl',
+]
+
+if CONFIG['MOZ_CRASHREPORTER']:
+    XPIDL_SOURCES += [
+        'nsICrashReporter.idl',
+    ]
+
+XPIDL_MODULE = 'xpcom_system'
diff --git a/xpcom/system/nsIBlocklistService.idl b/xpcom/system/nsIBlocklistService.idl
new file mode 100644
index 000000000..b70038431
--- /dev/null
+++ b/xpcom/system/nsIBlocklistService.idl
@@ -0,0 +1,140 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+#include "nsISupports.idl"
+
+interface nsIPluginTag;
+interface nsIVariant;
+
+[scriptable, uuid(a6dcc76e-9f62-4cc1-a470-b483a1a6f096)]
+interface nsIBlocklistService : nsISupports
+{
+  // Indicates that the item does not appear in the blocklist.
+  const unsigned long STATE_NOT_BLOCKED = 0;
+  // Indicates that the item is in the blocklist but the problem is not severe
+  // enough to warant forcibly blocking.
+  const unsigned long STATE_SOFTBLOCKED = 1;
+  // Indicates that the item should be blocked and never used.
+  const unsigned long STATE_BLOCKED     = 2;
+  // Indicates that the item is considered outdated, and there is a known
+  // update available.
+  const unsigned long STATE_OUTDATED    = 3;
+  // Indicates that the item is vulnerable and there is an update.
+  const unsigned long STATE_VULNERABLE_UPDATE_AVAILABLE = 4;
+  // Indicates that the item is vulnerable and there is no update.
+  const unsigned long STATE_VULNERABLE_NO_UPDATE = 5;
+
+  /**
+   * Determine if an item is blocklisted
+   * @param   addon
+   *          The addon item to be checked.
+   * @param   appVersion
+   *          The version of the application we are checking in the blocklist.
+   *          If this parameter is null, the version of the running application
+   *          is used.
+   * @param   toolkitVersion
+   *          The version of the toolkit we are checking in the blocklist.
+   *          If this parameter is null, the version of the running toolkit
+   *          is used.
+   * @returns true if the item is compatible with this version of the
+   *          application or this version of the toolkit, false, otherwise.
+   */
+  boolean isAddonBlocklisted(in jsval addon,
+                             [optional] in AString appVersion,
+                             [optional] in AString toolkitVersion);
+
+  /**
+   * Determine the blocklist state of an add-on
+   * @param   id
+   *          The addon item to be checked.
+   * @param   appVersion
+   *          The version of the application we are checking in the blocklist.
+   *          If this parameter is null, the version of the running application
+   *          is used.
+   * @param   toolkitVersion
+   *          The version of the toolkit we are checking in the blocklist.
+   *          If this parameter is null, the version of the running toolkit
+   *          is used.
+   * @returns The STATE constant.
+   */
+  unsigned long getAddonBlocklistState(in jsval addon,
+                                       [optional] in AString appVersion,
+                                       [optional] in AString toolkitVersion);
+
+  /**
+   * Determine the blocklist state of a plugin
+   * @param   plugin
+   *          The plugin to get the state for
+   * @param   appVersion
+   *          The version of the application we are checking in the blocklist.
+   *          If this parameter is null, the version of the running application
+   *          is used.
+   * @param   toolkitVersion
+   *          The version of the toolkit we are checking in the blocklist.
+   *          If this parameter is null, the version of the running toolkit
+   *          is used.
+   * @returns The STATE constant.
+   */
+  unsigned long getPluginBlocklistState(in nsIPluginTag plugin,
+                                        [optional] in AString appVersion,
+                                        [optional] in AString toolkitVersion);
+
+  /**
+   * Determine the blocklist web page of an add-on.
+   * @param   addon
+   *          The addon item whose url is required.
+   * @returns The URL of the description page.
+   */
+  AString getAddonBlocklistURL(in jsval addon,
+                              [optional] in AString appVersion,
+                              [optional] in AString toolkitVersion);
+
+  /**
+   * Determine the blocklist web page of a plugin.
+   * @param   plugin
+   *          The blocked plugin that we are determining the web page for.
+   * @returns The URL of the description page.
+   */
+  AString getPluginBlocklistURL(in nsIPluginTag plugin);
+
+  /**
+   * Determine the blocklist infoURL of a plugin.
+   * @param   plugin
+   *          The blocked plugin that we are determining the infoURL for.
+   * @returns The preferred URL to present the user, or |null| if
+   *          it is not available.
+   */
+  AString getPluginInfoURL(in nsIPluginTag plugin);
+};
+
+/**
+ * nsIBlocklistPrompt is used, if available, by the default implementation of 
+ * nsIBlocklistService to display a confirmation UI to the user before blocking
+ * extensions/plugins.
+ */
+[scriptable, uuid(ba915921-b9c0-400d-8e4f-ca1b80c5699a)]
+interface nsIBlocklistPrompt : nsISupports
+{
+  /**
+   * Prompt the user about newly blocked addons. The prompt is then resposible
+   * for soft-blocking any addons that need to be afterwards
+   *
+   * @param  aAddons
+   *         An array of addons and plugins that are blocked. These are javascript
+   *         objects with properties:
+   *          name    - the plugin or extension name,
+   *          version - the version of the extension or plugin,
+   *          icon    - the plugin or extension icon,
+   *          disable - can be used by the nsIBlocklistPrompt to allows users to decide
+   *                    whether a soft-blocked add-on should be disabled,
+   *          blocked - true if the item is hard-blocked, false otherwise,
+   *          item    - the nsIPluginTag or Addon object
+   * @param  aCount
+   *         The number of addons
+   */
+  void prompt([array, size_is(aCount)] in nsIVariant aAddons,
+              [optional] in uint32_t aCount);
+};
diff --git a/xpcom/system/nsICrashReporter.idl b/xpcom/system/nsICrashReporter.idl
new file mode 100644
index 000000000..c2f590098
--- /dev/null
+++ b/xpcom/system/nsICrashReporter.idl
@@ -0,0 +1,135 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIFile;
+interface nsIURL;
+
+/**
+ * Provides access to crash reporting functionality.
+ *
+ * @status UNSTABLE - This interface is not frozen and will probably change in
+ *                    future releases.
+ */
+
+[scriptable, uuid(4b74c39a-cf69-4a8a-8e63-169d81ad1ecf)]
+interface nsICrashReporter : nsISupports
+{
+  /**
+   * Get the enabled status of the crash reporter.
+   */
+  readonly attribute boolean enabled;
+
+  /**
+   * Enable or disable crash reporting at runtime. Not available to script
+   * because the JS engine relies on proper exception handler chaining.
+   */
+  [noscript]
+  void setEnabled(in bool enabled);
+
+  /**
+   * Get or set the URL to which crash reports will be submitted.
+   * Only https and http URLs are allowed, as the submission is handled
+   * by OS-native networking libraries.
+   *
+   * @throw NS_ERROR_NOT_INITIALIZED if crash reporting is not initialized
+   * @throw NS_ERROR_INVALID_ARG on set if a non-http(s) URL is assigned
+   * @throw NS_ERROR_FAILURE on get if no URL is set
+   */
+  attribute nsIURL serverURL;
+
+  /**
+   * Get or set the path on the local system to which minidumps will be
+   * written when a crash happens.
+   *
+   * @throw NS_ERROR_NOT_INITIALIZED if crash reporting is not initialized
+   */
+  attribute nsIFile minidumpPath;
+
+  /**
+   * Add some extra data to be submitted with a crash report.
+   *
+   * @param key
+   *        Name of the data to be added.
+   * @param data
+   *        Data to be added.
+   *
+   * @throw NS_ERROR_NOT_INITIALIZED if crash reporting not initialized
+   * @throw NS_ERROR_INVALID_ARG if key or data contain invalid characters.
+   *                             Invalid characters for key are '=' and
+   *                             '\n'.  Invalid character for data is '\0'.
+   */
+  void annotateCrashReport(in AUTF8String key, in AUTF8String data);
+
+  /**
+   * Append some data to the "Notes" field, to be submitted with a crash report.
+   * Unlike annotateCrashReport, this method will append to existing data.
+   *
+   * @param data
+   *        Data to be added.
+   *
+   * @throw NS_ERROR_NOT_INITIALIZED if crash reporting not initialized
+   * @throw NS_ERROR_INVALID_ARG if data contains invalid characters.
+   *                             The only invalid character is '\0'.
+   */
+  void appendAppNotesToCrashReport(in ACString data);
+
+  /**
+   * Register a given memory range to be included in the crash report.
+   *
+   * @param ptr
+   *        The starting address for the bytes.
+   * @param size
+   *        The number of bytes to include.
+   *
+   * @throw NS_ERROR_NOT_INITIALIZED if crash reporting not initialized
+   * @throw NS_ERROR_NOT_IMPLEMENTED if unavailable on the current OS
+   */
+  void registerAppMemory(in unsigned long long ptr, in unsigned long long size);
+
+  /**
+   * Write a minidump immediately, with the user-supplied exception
+   * information. This is implemented on Windows only, because
+   * SEH (structured exception handling) exists on Windows only.
+   *
+   * @param aExceptionInfo  EXCEPTION_INFO* provided by Window's SEH
+   */
+  [noscript] void writeMinidumpForException(in voidPtr aExceptionInfo);
+  
+  /**
+   * Append note containing an Obj-C exception's info.
+   *
+   * @param aException  NSException object to append note for
+   */
+  [noscript] void appendObjCExceptionInfoToAppNotes(in voidPtr aException);
+
+  /**
+   * User preference for submitting crash reports.
+   */
+  attribute boolean submitReports;
+
+  /**
+   * Cause the crash reporter to re-evaluate where crash events should go.
+   *
+   * This should be called during application startup and whenever profiles
+   * change.
+   */
+  void UpdateCrashEventsDir();
+
+  /**
+   * Save an anonymized memory report file for inclusion in a future crash
+   * report in this session.
+   *
+   * @throws NS_ERROR_NOT_INITIALIZED if crash reporting is disabled.
+   */
+  void saveMemoryReport();
+
+  /**
+   * Set the telemetry session ID which is recorded in crash metadata. This is
+   * saved in the crash manager and telemetry but is not submitted as a
+   * crash-stats annotation.
+   */
+  void setTelemetrySessionId(in AUTF8String id);
+};
diff --git a/xpcom/system/nsIDeviceSensors.idl b/xpcom/system/nsIDeviceSensors.idl
new file mode 100644
index 000000000..dcb67cb92
--- /dev/null
+++ b/xpcom/system/nsIDeviceSensors.idl
@@ -0,0 +1,60 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIDOMWindow;
+
+[scriptable, uuid(0462247e-fe8c-4aa5-b675-3752547e485f)]
+interface nsIDeviceSensorData : nsISupports
+{
+  // Keep in sync with hal/HalSensor.h
+
+  // 1. TYPE_ORIENTATION: absolute device orientation, not spec-conform and
+  // deprecated on Android.
+  // 2. TYPE_ROTATION_VECTOR: absolute device orientation affected by drift.
+  // 3. TYPE_GAME_ROTATION_VECTOR: relative device orientation less affected by drift.
+  // Preferred fallback priorities on Android are [3, 2, 1] for the general case
+  // and [2, 1] if absolute orientation (compass heading) is required.
+  const unsigned long TYPE_ORIENTATION = 0;
+  const unsigned long TYPE_ACCELERATION = 1;
+  const unsigned long TYPE_PROXIMITY = 2;
+  const unsigned long TYPE_LINEAR_ACCELERATION = 3;
+  const unsigned long TYPE_GYROSCOPE = 4;
+  const unsigned long TYPE_LIGHT = 5;
+  const unsigned long TYPE_ROTATION_VECTOR = 6;
+  const unsigned long TYPE_GAME_ROTATION_VECTOR = 7;
+
+  readonly attribute unsigned long type;
+
+  readonly attribute double x;
+  readonly attribute double y;
+  readonly attribute double z;
+};
+
+[scriptable, uuid(e46e47c7-55ff-44c4-abce-21b14ba07f86)]
+interface nsIDeviceSensors : nsISupports
+{
+  /**
+   * Returns true if the given window has any listeners of the given type
+   */
+  bool hasWindowListener(in unsigned long aType, in nsIDOMWindow aWindow);
+
+  // Holds pointers, not AddRef objects -- it is up to the caller
+  // to call RemoveWindowListener before the window is deleted.
+
+  [noscript] void addWindowListener(in unsigned long aType, in nsIDOMWindow aWindow);
+  [noscript] void removeWindowListener(in unsigned long aType, in nsIDOMWindow aWindow);
+  [noscript] void removeWindowAsListener(in nsIDOMWindow aWindow);
+};
+
+%{C++
+
+#define NS_DEVICE_SENSORS_CID \
+{ 0xecba5203, 0x77da, 0x465a, \
+{ 0x86, 0x5e, 0x78, 0xb7, 0xaf, 0x10, 0xd8, 0xf7 } }
+
+#define NS_DEVICE_SENSORS_CONTRACTID "@mozilla.org/devicesensors;1"
+
+%}
diff --git a/xpcom/system/nsIGConfService.idl b/xpcom/system/nsIGConfService.idl
new file mode 100644
index 000000000..ccc02610f
--- /dev/null
+++ b/xpcom/system/nsIGConfService.idl
@@ -0,0 +1,50 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIArray;
+
+[scriptable, uuid(5009acae-6973-48c3-b6d6-52c692cc5d9d)]
+interface nsIGConfService : nsISupports
+{
+  /* Basic registry access */
+  boolean       getBool(in AUTF8String key);
+  AUTF8String   getString(in AUTF8String key);
+  long          getInt(in AUTF8String key);
+  float         getFloat(in AUTF8String key);
+
+  /*
+   * Use this to return any list items in GConf, this will return
+   * an array of UTF16 nsISupportsString's.
+   */
+  nsIArray      getStringList(in AUTF8String key);
+
+  void setBool(in AUTF8String key, in boolean value);
+  void setString(in AUTF8String key, in AUTF8String value);
+  void setInt(in AUTF8String key, in long value);
+  void setFloat(in AUTF8String key, in float value);
+
+  /*
+   * Look up the handler for a protocol under the
+   * /desktop/gnome/url-handlers hierarchy.
+   */
+  AUTF8String getAppForProtocol(in AUTF8String scheme, out boolean enabled);
+
+  /*
+   * Check whether the handler for a scheme requires a terminal to run.
+   */
+  boolean handlerRequiresTerminal(in AUTF8String scheme);
+
+  /*
+   * Set the handler for a protocol, marking it as enabled.
+   * This removes any GnomeVFSMimeApp association for the protocol.
+   */
+  void   setAppForProtocol(in AUTF8String scheme, in AUTF8String command);
+};
+
+%{C++
+#define NS_GCONFSERVICE_CONTRACTID "@mozilla.org/gnome-gconf-service;1"
+%}
diff --git a/xpcom/system/nsIGIOService.idl b/xpcom/system/nsIGIOService.idl
new file mode 100644
index 000000000..cbbdabe7e
--- /dev/null
+++ b/xpcom/system/nsIGIOService.idl
@@ -0,0 +1,82 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIUTF8StringEnumerator;
+interface nsIURI;
+
+/* nsIGIOMimeApp holds information about an application that is looked up
+   with nsIGIOService::GetAppForMimeType. */
+// 66009894-9877-405b-9321-bf30420e34e6 prev uuid
+
+[scriptable, uuid(ca6bad0c-8a48-48ac-82c7-27bb8f510fbe)] 
+interface nsIGIOMimeApp : nsISupports
+{
+  const long EXPECTS_URIS  = 0;
+  const long EXPECTS_PATHS = 1;
+  const long EXPECTS_URIS_FOR_NON_FILES = 2;
+
+  readonly attribute AUTF8String         id;
+  readonly attribute AUTF8String         name;
+  readonly attribute AUTF8String         command;
+  readonly attribute long                expectsURIs;  // see constants above
+  readonly attribute nsIUTF8StringEnumerator supportedURISchemes;
+
+  void launch(in AUTF8String uri);
+  void setAsDefaultForMimeType(in AUTF8String mimeType);
+  void setAsDefaultForFileExtensions(in AUTF8String extensions);
+  void setAsDefaultForURIScheme(in AUTF8String uriScheme);
+};
+
+/*
+ * The VFS service makes use of two distinct registries.
+ *
+ * The application registry holds information about applications (uniquely
+ * identified by id), such as which MIME types and URI schemes they are
+ * capable of handling, whether they run in a terminal, etc.
+ *
+ * The MIME registry holds information about MIME types, such as which
+ * extensions map to a given MIME type.  The MIME registry also stores the
+ * id of the application selected to handle each MIME type.
+ */
+
+// prev id dea20bf0-4e4d-48c5-b932-dc3e116dc64b
+[scriptable, uuid(eda22a30-84e1-4e16-9ca0-cd1553c2b34a)]
+interface nsIGIOService : nsISupports
+{
+
+  /*** MIME registry methods ***/
+
+  /* Obtain the MIME type registered for an extension.  The extension
+     should not include a leading dot. */
+  AUTF8String        getMimeTypeFromExtension(in AUTF8String extension);
+
+  /* Obtain the preferred application for opening a given URI scheme */
+  nsIGIOMimeApp      getAppForURIScheme(in AUTF8String aURIScheme);
+
+  /* Obtain the preferred application for opening a given MIME type */
+  nsIGIOMimeApp      getAppForMimeType(in AUTF8String mimeType);
+
+  /* Obtain the preferred application for opening a given MIME type */
+  nsIGIOMimeApp      createAppFromCommand(in AUTF8String cmd, 
+                                          in AUTF8String appName);
+
+  /* Obtain a description for the given MIME type */
+  AUTF8String        getDescriptionForMimeType(in AUTF8String mimeType);
+
+  /*** Misc. methods ***/
+
+  /* Open the given URI in the default application */
+  void               showURI(in nsIURI uri);
+  [noscript] void    showURIForInput(in ACString uri);
+
+  /* Open path in file manager using org.freedesktop.FileManager1 interface */
+  [noscript] void    orgFreedesktopFileManager1ShowItems(in ACString path);
+};
+
+%{C++
+#define NS_GIOSERVICE_CONTRACTID "@mozilla.org/gio-service;1"
+%}
diff --git a/xpcom/system/nsIGSettingsService.idl b/xpcom/system/nsIGSettingsService.idl
new file mode 100644
index 000000000..26d86a77e
--- /dev/null
+++ b/xpcom/system/nsIGSettingsService.idl
@@ -0,0 +1,30 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIArray;
+
+[scriptable, uuid(16d5b0ed-e756-4f1b-a8ce-9132e869acd8)]
+interface nsIGSettingsCollection : nsISupports
+{
+  void          setString(in AUTF8String key, in AUTF8String value);
+  void          setBoolean(in AUTF8String key, in boolean value);
+  void          setInt(in AUTF8String key, in long value);
+  AUTF8String   getString(in AUTF8String key);
+  boolean       getBoolean(in AUTF8String key);
+  long          getInt(in AUTF8String key);
+  nsIArray      getStringList(in AUTF8String key);
+};
+
+[scriptable, uuid(849c088b-57d1-4f24-b7b2-3dc4acb04c0a)]
+interface nsIGSettingsService : nsISupports
+{
+  nsIGSettingsCollection    getCollectionForSchema(in AUTF8String schema);
+};
+
+%{C++
+#define NS_GSETTINGSSERVICE_CONTRACTID "@mozilla.org/gsettings-service;1"
+%}
diff --git a/xpcom/system/nsIGeolocationProvider.idl b/xpcom/system/nsIGeolocationProvider.idl
new file mode 100644
index 000000000..29044266d
--- /dev/null
+++ b/xpcom/system/nsIGeolocationProvider.idl
@@ -0,0 +1,83 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+
+#include "nsISupports.idl"
+
+interface nsIURI;
+interface nsIDOMWindow;
+interface nsIDOMElement;
+interface nsIDOMGeoPosition;
+interface nsIGeolocationPrompt;
+
+/**
+
+ * Interface provides a way for a geolocation provider to
+ * notify the system that a new location is available.
+ */
+[scriptable, uuid(643dc5e9-b911-4b2c-8d44-603162696baf)]
+interface nsIGeolocationUpdate : nsISupports {
+
+  /**
+   * Notify the geolocation service that a new geolocation
+   * has been discovered.
+   * This must be called on the main thread
+   */
+  void update(in nsIDOMGeoPosition position);
+  /**
+   * Notify the geolocation service of an error.
+   * This must be called on the main thread.
+   * The parameter refers to one of the constants in the
+   * nsIDOMGeoPositionError interface.
+   * Use this to report spurious errors coming from the
+   * provider; for errors occurring inside the methods in
+   * the nsIGeolocationProvider interface, just use the return
+   * value.
+   */
+  void notifyError(in unsigned short error);
+};
+
+
+/**
+ * Interface provides location information to the nsGeolocator
+ * via the nsIDOMGeolocationCallback interface.  After
+ * startup is called, any geo location change should call
+ * callback.update().
+ */
+[scriptable, uuid(AC4A133B-9F92-4F7C-B369-D40CB6B17650)]
+interface nsIGeolocationProvider : nsISupports {
+
+  /**
+   * Start up the provider.  This is called before any other
+   * method.  may be called multiple times.
+   */
+  void startup();
+
+  /**
+   * watch
+   * When a location change is observed, notify the callback.
+   */
+  void watch(in nsIGeolocationUpdate callback);
+
+  /**
+   * shutdown
+   * Shuts down the location device.
+   */
+  void shutdown();
+
+  /**
+   * hint to provide to use any amount of power to provide a better result
+   */
+  void setHighAccuracy(in boolean enable);
+
+};
+
+%{C++
+/*
+    This must be implemented by geolocation providers.  It
+    must support nsIGeolocationProvider.
+*/
+#define NS_GEOLOCATION_PROVIDER_CONTRACTID "@mozilla.org/geolocation/provider;1"
+%}
diff --git a/xpcom/system/nsIHapticFeedback.idl b/xpcom/system/nsIHapticFeedback.idl
new file mode 100644
index 000000000..25d0d8e7b
--- /dev/null
+++ b/xpcom/system/nsIHapticFeedback.idl
@@ -0,0 +1,22 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+
+[scriptable, uuid(91917c98-a8f3-4c98-8f10-4afb872f54c7)]
+interface nsIHapticFeedback : nsISupports {
+
+    const long ShortPress = 0;
+    const long LongPress  = 1;
+
+  /**
+     * Perform haptic feedback
+     *
+     * @param isLongPress
+     *        indicate whether feedback is for a long press (vs. short press)
+     */
+    void performSimpleAction(in long isLongPress);
+};
diff --git a/xpcom/system/nsIPackageKitService.idl b/xpcom/system/nsIPackageKitService.idl
new file mode 100644
index 000000000..5cd3494a3
--- /dev/null
+++ b/xpcom/system/nsIPackageKitService.idl
@@ -0,0 +1,46 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIArray;
+interface nsIObserver;
+
+[scriptable, uuid(89bb04f6-ce2a-11e3-8f4f-60a44c717042)]
+interface nsIPackageKitService : nsISupports
+{
+
+  /* PackageKit installation methods */
+  /* See https://github.com/nekohayo/gnome-packagekit/blob/master/src/org.freedesktop.PackageKit.xml */
+  const unsigned long PK_INSTALL_PACKAGE_NAMES = 0;
+  const unsigned long PK_INSTALL_MIME_TYPES = 1;
+  const unsigned long PK_INSTALL_FONTCONFIG_RESOURCES = 2;
+  const unsigned long PK_INSTALL_GSTREAMER_RESOURCES = 3;
+  const unsigned long PK_INSTALL_METHOD_COUNT = 4;
+
+  /* Ask to install a list of packages via PackageKit
+   * @param   packageKitMethod
+   *          The PackageKit installation method
+   * @param   packageArray
+   *          A nonempty array of strings describing the list of packages to
+   *          install.
+   * @param   An object implementing nsIObserver that will be notified with
+   *          a message of topic "packagekit-install". The message data
+   *          contains the error returned by PackageKit if the installation
+   *          fails and is null otherwise.
+   *
+   * This function may raise an NS_ERROR_INVALID_ARG, NS_ERROR_FAILURE or
+   * NS_ERROR_OUT_OF_MEMORY exception. Otherwise, the observer will be notified
+   * when the operation completes.
+   *
+   */
+  void installPackages(in unsigned long packageKitMethod,
+                       in nsIArray packageArray,
+                       in nsIObserver observer);
+};
+
+%{C++
+#define NS_PACKAGEKITSERVICE_CONTRACTID "@mozilla.org/packagekit-service;1"
+%}
diff --git a/xpcom/system/nsIPlatformInfo.idl b/xpcom/system/nsIPlatformInfo.idl
new file mode 100644
index 000000000..fba78b6ec
--- /dev/null
+++ b/xpcom/system/nsIPlatformInfo.idl
@@ -0,0 +1,19 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+[scriptable, uuid(ab6650cf-0806-4aea-b8f2-40fdae74f1cc)]
+interface nsIPlatformInfo : nsISupports
+{
+  /**
+   * The version of the XULRunner platform.
+   */
+  readonly attribute ACString platformVersion;
+
+  /**
+   * The build ID/date of gecko and the XULRunner platform.
+   */
+  readonly attribute ACString platformBuildID;
+};
diff --git a/xpcom/system/nsIXULAppInfo.idl b/xpcom/system/nsIXULAppInfo.idl
new file mode 100644
index 000000000..1ea9208a3
--- /dev/null
+++ b/xpcom/system/nsIXULAppInfo.idl
@@ -0,0 +1,53 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIPlatformInfo.idl"
+
+/**
+ * A scriptable interface to the nsXULAppAPI structure. See nsXULAppAPI.h for
+ * a detailed description of each attribute.
+ */
+
+[scriptable, uuid(ddea4f31-3c5e-4769-ac68-21ab4b3d7845)]
+interface nsIXULAppInfo : nsIPlatformInfo
+{
+  /**
+   * @see nsXREAppData.vendor
+   * @returns an empty string if nsXREAppData.vendor is not set.
+   */
+  readonly attribute ACString vendor;
+
+  /**
+   * @see nsXREAppData.name
+   */
+  readonly attribute ACString name;
+
+  /**
+   * @see nsXREAppData.ID
+   * @returns an empty string if nsXREAppData.ID is not set.
+   */
+  readonly attribute ACString ID;
+
+  /**
+   * The version of the XUL application. It is different than the
+   * version of the XULRunner platform. Be careful about which one you want.
+   *
+   * @see nsXREAppData.version
+   * @returns an empty string if nsXREAppData.version is not set.
+   */
+  readonly attribute ACString version;
+
+  /**
+   * The build ID/date of the application. For xulrunner applications,
+   * this will be different than the build ID of the platform. Be careful
+   * about which one you want.
+   */
+  readonly attribute ACString appBuildID;
+
+  /**
+   * @see nsXREAppData.UAName
+   * @returns an empty string if nsXREAppData.UAName is not set.
+   */
+  readonly attribute ACString UAName;
+};
diff --git a/xpcom/system/nsIXULRuntime.idl b/xpcom/system/nsIXULRuntime.idl
new file mode 100644
index 000000000..fda0e696f
--- /dev/null
+++ b/xpcom/system/nsIXULRuntime.idl
@@ -0,0 +1,176 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+%{C++
+
+namespace mozilla {
+// Simple C++ getter for nsIXULRuntime::browserTabsRemoteAutostart
+// This getter is a temporary function that checks for special
+// conditions in which e10s support is not great yet, and should
+// therefore be disabled. Bug 1065561 tracks its removal.
+bool BrowserTabsRemoteAutostart();
+}
+
+%}
+
+/**
+ * Provides information about the XUL runtime.
+ * @status UNSTABLE - This interface is not frozen and will probably change in
+ *                    future releases. If you need this functionality to be
+ *                    stable/frozen, please contact Benjamin Smedberg.
+ */
+
+[scriptable, uuid(a1b2e167-b748-42bf-ba85-996ec39062b9)]
+interface nsIXULRuntime : nsISupports
+{
+  /**
+   * Whether the application was launched in safe mode.
+   */
+  readonly attribute boolean inSafeMode;
+
+  /**
+   * Whether to write console errors to a log file. If a component
+   * encounters startup errors that might prevent the app from showing
+   * proper UI, it should set this flag to "true".
+   */
+  attribute boolean logConsoleErrors;
+
+  /**
+   * A string tag identifying the current operating system. This is taken
+   * from the OS_TARGET configure variable. It will always be available.
+   */
+  readonly attribute AUTF8String OS;
+
+  /**
+   * A string tag identifying the binary ABI of the current processor and
+   * compiler vtable. This is taken from the TARGET_XPCOM_ABI configure
+   * variable. It may not be available on all platforms, especially
+   * unusual processor or compiler combinations.
+   *
+   * The result takes the form <processor>-<compilerABI>, for example:
+   *   x86-msvc
+   *   ppc-gcc3
+   *
+   * This value should almost always be used in combination with "OS".
+   *
+   * @throw NS_ERROR_NOT_AVAILABLE if not available.
+   */
+  readonly attribute AUTF8String XPCOMABI;
+
+  /**
+   * A string tag identifying the target widget toolkit in use.
+   * This is taken from the MOZ_WIDGET_TOOLKIT configure variable.
+   */
+  readonly attribute AUTF8String widgetToolkit;
+
+  /**
+   * The legal values of processType.
+   */
+  const unsigned long PROCESS_TYPE_DEFAULT = 0;
+  const unsigned long PROCESS_TYPE_PLUGIN = 1;
+  const unsigned long PROCESS_TYPE_CONTENT = 2;
+  const unsigned long PROCESS_TYPE_IPDLUNITTEST = 3;
+  const unsigned long PROCESS_TYPE_GMPLUGIN = 4;
+  const unsigned long PROCESS_TYPE_GPU = 5;
+
+  /**
+   * The type of the caller's process.  Returns one of the values above.
+   */
+  readonly attribute unsigned long processType;
+
+  /**
+   * The system process ID of the caller's process.
+   */
+  readonly attribute unsigned long processID;
+
+  /**
+   * A globally unique and non-recycled ID of the caller's process.
+   */
+  readonly attribute uint64_t uniqueProcessID;
+
+  /**
+   * If true, browser tabs may be opened by default in a different process
+   * from the main browser UI.
+   */
+  readonly attribute boolean browserTabsRemoteAutostart;
+
+  /**
+   * A numeric value indicating whether multiprocess might be blocked.
+   * Possible values can be found at nsAppRunner.cpp. A value of 0
+   * represents not blocking.
+   */
+   readonly attribute unsigned long multiprocessBlockPolicy;
+
+  /**
+   * If true, the accessibility service is running.
+   */
+  readonly attribute boolean accessibilityEnabled;
+
+  /**
+   * Indicates whether the current Firefox build is 64-bit.
+   */
+  readonly attribute boolean is64Bit;
+
+  /**
+   * Signal the apprunner to invalidate caches on the next restart.
+   * This will cause components to be autoregistered and all
+   * fastload data to be re-created.
+   */
+  void invalidateCachesOnRestart();
+
+  /**
+   * Starts a child process. This method is intented to pre-start a
+   * content child process so that when it is actually needed, it is
+   * ready to go.
+   *
+   * @throw NS_ERROR_NOT_AVAILABLE if not available.
+   */
+  void ensureContentProcess();
+
+  /**
+   * Modification time of the profile lock before the profile was locked on
+   * this startup. Used to know the last time the profile was used and not
+   * closed cleanly. This is set to 0 if there was no existing profile lock.
+   */
+  readonly attribute PRTime replacedLockTime;
+
+  /**
+   * Local ID of the minidump generated when the process crashed
+   * on the previous run. Can be passed directly to CrashSubmit.submit.
+   */
+  readonly attribute DOMString lastRunCrashID;
+
+  /**
+   * True if this is RELEASE_OR_BETA.
+   */
+  readonly attribute boolean isReleaseOrBeta;
+
+  /**
+   * True if this build uses official branding (MOZ_OFFICIAL_BRANDING).
+   */
+  readonly attribute boolean isOfficialBranding;
+
+  /**
+   * The default update channel (MOZ_UPDATE_CHANNEL).
+   */
+  readonly attribute AUTF8String defaultUpdateChannel;
+
+  /**
+   * The distribution ID for this build (MOZ_DISTRIBUTION_ID).
+   */
+  readonly attribute AUTF8String distributionID;
+
+  /**
+   * True if this is an official build (MOZILLA_OFFICIAL).
+   */
+  readonly attribute boolean isOfficial;
+
+  /**
+   * True if Windows DLL blocklist initialized correctly. This is
+   * primarily for automated testing purposes.
+   */
+  readonly attribute boolean windowsDLLBlocklistStatus;
+};
diff --git a/xpcom/tests/Makefile.in b/xpcom/tests/Makefile.in
new file mode 100644
index 000000000..75796b93b
--- /dev/null
+++ b/xpcom/tests/Makefile.in
@@ -0,0 +1,13 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# Make sure we have symbols in case we need to debug these.
+MOZ_DEBUG_SYMBOLS = 1
+
+include $(topsrcdir)/config/rules.mk
+
+ifneq (,$(SIMPLE_PROGRAMS))
+libs::
+	$(INSTALL) $(SIMPLE_PROGRAMS) $(DEPTH)/_tests/xpcshell/$(relativesrcdir)/unit
+endif
diff --git a/xpcom/tests/NotXPCOMTest.idl b/xpcom/tests/NotXPCOMTest.idl
new file mode 100644
index 000000000..75d1e73da
--- /dev/null
+++ b/xpcom/tests/NotXPCOMTest.idl
@@ -0,0 +1,23 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+[scriptable, uuid(93142a4f-e4cf-424a-b833-e638f87d2607)]
+interface ScriptableOK : nsISupports
+{
+  void method1();
+};
+
+[scriptable, uuid(237d01a3-771e-4c6e-adf9-c97f9aab2950)]
+interface ScriptableWithNotXPCOM : nsISupports
+{
+  [notxpcom] void method2();
+};
+
+[scriptable, uuid(4f06ec60-3bb3-4712-ab18-b2b595285558)]
+interface ScriptableWithNotXPCOMBase : ScriptableWithNotXPCOM
+{
+  void method3();
+};
diff --git a/xpcom/tests/RegFactory.cpp b/xpcom/tests/RegFactory.cpp
new file mode 100644
index 000000000..0abb7a4e8
--- /dev/null
+++ b/xpcom/tests/RegFactory.cpp
@@ -0,0 +1,130 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <iostream.h>
+#include "plstr.h"
+#include "prlink.h"
+#include "nsIComponentRegistrar.h"
+#include "nsIComponentManager.h"
+#include "nsIServiceManager.h"
+#include "nsIFile.h"
+#include "nsCOMPtr.h"
+#include "nsString.h"
+
+static bool gUnreg = false;
+
+void print_err(nsresult err)
+{
+  switch (err) {
+  case NS_ERROR_FACTORY_NOT_LOADED:
+    cerr << "Factory not loaded";
+    break;
+  case NS_NOINTERFACE:
+    cerr << "No Interface";
+    break;
+  case NS_ERROR_NULL_POINTER:
+    cerr << "Null pointer";
+    break;
+  case NS_ERROR_OUT_OF_MEMORY:
+    cerr << "Out of memory";
+    break;
+  default:
+    cerr << hex << err << dec;
+  }
+}
+
+nsresult Register(nsIComponentRegistrar* registrar, const char *path) 
+{ 
+  nsCOMPtr<nsIFile> file;
+  nsresult rv =
+    NS_NewLocalFile(
+      NS_ConvertUTF8toUTF16(path),
+      true,
+      getter_AddRefs(file));
+  if (NS_FAILED(rv)) return rv;
+  rv = registrar->AutoRegister(file);
+  return rv;
+}
+
+nsresult Unregister(const char *path) 
+{
+  /* NEEDS IMPLEMENTATION */
+#if 0
+    nsresult res = nsComponentManager::AutoUnregisterComponent(path);
+  return res;
+#else
+  return NS_ERROR_FAILURE;
+#endif
+}
+
+int ProcessArgs(nsIComponentRegistrar* registrar, int argc, char *argv[])
+{
+  int i = 1;
+  nsresult res;
+
+  while (i < argc) {
+    if (argv[i][0] == '-') {
+      int j;
+      for (j = 1; argv[i][j] != '\0'; j++) {
+        switch (argv[i][j]) {
+        case 'u':
+          gUnreg = true;
+          break;
+        default:
+          cerr << "Unknown option '" << argv[i][j] << "'\n";
+        }
+      }
+      i++;
+    } else {
+      if (gUnreg) {
+        res = Unregister(argv[i]);
+        if (NS_SUCCEEDED(res)) {
+          cout << "Successfully unregistered: " << argv[i] << "\n";
+        } else {
+          cerr << "Unregister failed (";
+          print_err(res);
+          cerr << "): " << argv[i] << "\n";
+        }
+      } else {
+        res = Register(registrar, argv[i]);
+        if (NS_SUCCEEDED(res)) {
+          cout << "Successfully registered: " << argv[i] << "\n";
+        } else {
+          cerr << "Register failed (";
+          print_err(res);
+          cerr << "): " << argv[i] << "\n";
+        }
+      }
+      i++;
+    }
+  }
+  return 0;
+}
+
+int main(int argc, char *argv[])
+{
+  int ret = 0;
+  nsresult rv;
+  {
+    nsCOMPtr<nsIServiceManager> servMan;
+    rv = NS_InitXPCOM2(getter_AddRefs(servMan), nullptr, nullptr);
+    if (NS_FAILED(rv)) return -1;
+    nsCOMPtr<nsIComponentRegistrar> registrar = do_QueryInterface(servMan);
+    NS_ASSERTION(registrar, "Null nsIComponentRegistrar");
+
+    /* With no arguments, RegFactory will autoregister */
+    if (argc <= 1)
+    {
+      rv = registrar->AutoRegister(nullptr);
+      ret = (NS_FAILED(rv)) ? -1 : 0;
+    }
+    else
+      ret = ProcessArgs(registrar, argc, argv);
+  } // this scopes the nsCOMPtrs
+  // no nsCOMPtrs are allowed to be alive when you call NS_ShutdownXPCOM
+  rv = NS_ShutdownXPCOM(nullptr);
+  NS_ASSERTION(NS_SUCCEEDED(rv), "NS_ShutdownXPCOM failed");
+  return ret;
+}
diff --git a/xpcom/tests/SizeTest01.cpp b/xpcom/tests/SizeTest01.cpp
new file mode 100644
index 000000000..cdb7f00c0
--- /dev/null
+++ b/xpcom/tests/SizeTest01.cpp
@@ -0,0 +1,107 @@
+// Test01.cpp
+
+#include "nsIDOMNode.h"
+#include "nsCOMPtr.h"
+#include "nsString.h"
+
+NS_DEF_PTR(nsIDOMNode);
+
+	/*
+		This test file compares the generated code size of similar functions between raw
+                COM interface pointers (|AddRef|ing and |Release|ing by hand) and |nsCOMPtr|s.
+
+		Function size results were determined by examining dissassembly of the generated code.
+		mXXX is the size of the generated code on the Macintosh.  wXXX is the size on Windows.
+		For these tests, all reasonable optimizations were enabled and exceptions were
+		disabled (just as we build for release).
+
+		The tests in this file explore only the simplest functionality: assigning a pointer
+                to be reference counted into a [raw, nsCOMPtr] object; ensuring that it is
+		|AddRef|ed and |Release|d appropriately; calling through the pointer to a function
+		supplied by the underlying COM interface.
+
+		Windows:
+			raw_optimized														 31 bytes
+			raw, nsCOMPtr*													 34
+			nsCOMPtr_optimized*											 38
+			nsCOMPtr_optimized											 42
+			nsCOMPtr																 46
+
+		Macintosh:
+			raw_optimized, nsCOMPtr_optimized				112 bytes 	(1.0000)
+			nsCOMPtr																120					(1.0714)	i.e., 7.14% bigger than raw_optimized et al
+			raw																			140 				(1.2500)
+
+		The overall difference in size between Windows and Macintosh is caused by the
+		the PowerPC RISC architecture where every instruction is 4 bytes.
+
+                On Macintosh, nsCOMPtr generates out-of-line destructors which are
+		not referenced, and which can be stripped by the linker.
+	*/
+
+void
+Test01_raw( nsIDOMNode* aDOMNode, nsString* aResult )
+		// m140, w34
+	{
+			/*
+				This test is designed to be more like a typical large function where,
+				because you are working with several resources, you don't just return when
+				one of them is |nullptr|.  Similarly: |Test01_nsCOMPtr00|, and |Test01_nsIPtr00|.
+			*/
+
+		nsIDOMNode* node = aDOMNode;
+		NS_IF_ADDREF(node);
+
+		if ( node )
+			node->GetNodeName(*aResult);
+
+		NS_IF_RELEASE(node);
+	}
+
+void
+Test01_raw_optimized( nsIDOMNode* aDOMNode, nsString* aResult )
+		// m112, w31
+	{
+			/*
+				This test simulates smaller functions where you _do_ just return
+				|nullptr| at the first sign of trouble.  Similarly: |Test01_nsCOMPtr01|,
+				and |Test01_nsIPtr01|.
+			*/
+
+			/*
+				This test produces smaller code that |Test01_raw| because it avoids
+				the three tests: |NS_IF_...|, and |if ( node )|.
+			*/
+
+// -- the following code is assumed, but is commented out so we compare only
+//		 the relevent generated code
+
+//		if ( !aDOMNode )
+//			return;
+
+		nsIDOMNode* node = aDOMNode;
+		NS_ADDREF(node);
+		node->GetNodeName(*aResult);
+		NS_RELEASE(node);
+	}
+
+void
+Test01_nsCOMPtr( nsIDOMNode* aDOMNode, nsString* aResult )
+		// m120, w46/34
+	{
+		nsCOMPtr<nsIDOMNode> node = aDOMNode;
+
+		if ( node )
+			node->GetNodeName(*aResult);
+	}
+
+void
+Test01_nsCOMPtr_optimized( nsIDOMNode* aDOMNode, nsString* aResult )
+		// m112, w42/38
+	{
+//		if ( !aDOMNode )
+//			return;
+
+		nsCOMPtr<nsIDOMNode> node = aDOMNode;
+		node->GetNodeName(*aResult);
+	}
diff --git a/xpcom/tests/SizeTest02.cpp b/xpcom/tests/SizeTest02.cpp
new file mode 100644
index 000000000..9fcd1a0ca
--- /dev/null
+++ b/xpcom/tests/SizeTest02.cpp
@@ -0,0 +1,89 @@
+// Test02.cpp
+
+#include "nsIDOMNode.h"
+#include "nsCOMPtr.h"
+#include "nsString.h"
+
+NS_DEF_PTR(nsIDOMNode);
+
+	/*
+		This test file compares the generated code size of similar functions between raw
+                COM interface pointers (|AddRef|ing and |Release|ing by hand) and |nsCOMPtr|s.
+
+		Function size results were determined by examining dissassembly of the generated code.
+		mXXX is the size of the generated code on the Macintosh.  wXXX is the size on Windows.
+		For these tests, all reasonable optimizations were enabled and exceptions were
+		disabled (just as we build for release).
+
+		The tests in this file explore more complicated functionality: assigning a pointer
+                to be reference counted into a [raw, nsCOMPtr] object using |QueryInterface|;
+		ensuring that it is |AddRef|ed and |Release|d appropriately; calling through the pointer
+		to a function supplied by the underlying COM interface.  The tests in this file expand
+		on the tests in "Test01.cpp" by adding |QueryInterface|.
+
+		Windows:
+			raw01									 52
+			nsCOMPtr							 63
+			raw										 66
+			nsCOMPtr*							 68
+
+		Macintosh:
+			nsCOMPtr							120 	(1.0000)
+			Raw01									128		(1.1429)	i.e., 14.29% bigger than nsCOMPtr
+			Raw00									144		(1.2000)
+	*/
+
+
+void // nsresult
+Test02_Raw00( nsISupports* aDOMNode, nsString* aResult )
+		// m144, w66
+	{
+// -- the following code is assumed, but is commented out so we compare only
+//		 the relevent generated code
+
+//		if ( !aDOMNode )
+//			return NS_ERROR_NULL_POINTER;
+
+		nsIDOMNode* node = 0;
+		nsresult status = aDOMNode->QueryInterface(NS_GET_IID(nsIDOMNode), (void**)&node);
+		if ( NS_SUCCEEDED(status) )
+			{
+				node->GetNodeName(*aResult);
+			}
+
+		NS_IF_RELEASE(node);
+
+//		return status;
+	}
+
+void // nsresult
+Test02_Raw01( nsISupports* aDOMNode, nsString* aResult )
+		// m128, w52
+	{
+//		if ( !aDOMNode )
+//			return NS_ERROR_NULL_POINTER;
+
+		nsIDOMNode* node;
+                nsresult status = aDOMNode->QueryInterface(NS_GET_IID(nsIDOMNode), (void**)&node);
+		if ( NS_SUCCEEDED(status) )
+			{
+				node->GetNodeName(*aResult);
+				NS_RELEASE(node);
+			}
+
+//		return status;
+	}
+
+void // nsresult
+Test02_nsCOMPtr( nsISupports* aDOMNode, nsString* aResult )
+		// m120, w63/68
+	{
+		nsresult status;
+		nsCOMPtr<nsIDOMNode> node = do_QueryInterface(aDOMNode, &status);
+		
+		if ( node )
+			node->GetNodeName(*aResult);
+
+//		return status;
+	}
+
diff --git a/xpcom/tests/SizeTest03.cpp b/xpcom/tests/SizeTest03.cpp
new file mode 100644
index 000000000..e1593171e
--- /dev/null
+++ b/xpcom/tests/SizeTest03.cpp
@@ -0,0 +1,97 @@
+// Test03.cpp
+
+#include "nsIDOMNode.h"
+#include "nsCOMPtr.h"
+#include "nsString.h"
+
+NS_DEF_PTR(nsIDOMNode);
+
+	/*
+		Windows:
+			nsCOMPtr_optimized*											 45
+			raw_optimized														 48
+			nsCOMPtr_optimized											 50
+			nsCOMPtr																 54
+			nsCOMPtr*																 59
+			raw																			 62
+
+		Macintosh:
+			nsCOMPtr_optimized		112					(1.0000)
+			raw_optimized					124 bytes		(1.1071)	i.e., 10.71% bigger than nsCOMPtr_optimized
+			nsCOMPtr							144					(1.2857)
+	*/
+
+void // nsresult
+Test03_raw( nsIDOMNode* aDOMNode, nsString* aResult )
+		// m140, w62
+	{
+// -- the following code is assumed, but is commented out so we compare only
+//		 the relevent generated code
+
+//		if ( !aDOMNode || !aResult )
+//			return NS_ERROR_NULL_POINTER;
+
+		nsIDOMNode* parent = 0;
+		nsresult status = aDOMNode->GetParentNode(&parent);
+		
+		if ( NS_SUCCEEDED(status) )
+			{
+				parent->GetNodeName(*aResult);
+			}
+
+		NS_IF_RELEASE(parent);
+
+//		return status;
+	}
+
+
+void // nsresult
+Test03_raw_optimized( nsIDOMNode* aDOMNode, nsString* aResult )
+		// m124, w48
+	{
+//		if ( !aDOMNode || !aResult )
+//			return NS_ERROR_NULL_POINTER;
+
+		nsIDOMNode* parent;
+		nsresult status = aDOMNode->GetParentNode(&parent);
+		
+		if ( NS_SUCCEEDED(status) )
+			{
+				parent->GetNodeName(*aResult);
+				NS_RELEASE(parent);
+			}
+
+//		return status;
+	}
+
+
+void // nsresult
+Test03_nsCOMPtr( nsIDOMNode* aDOMNode, nsString* aResult )
+		// m144, w54/59
+	{
+//		if ( !aDOMNode || !aResult )
+//			return NS_ERROR_NULL_POINTER;
+
+		nsCOMPtr<nsIDOMNode> parent;
+		nsresult status = aDOMNode->GetParentNode( getter_AddRefs(parent) );
+		if ( parent )
+			parent->GetNodeName(*aResult);
+
+//		return status;
+	}
+
+void // nsresult
+Test03_nsCOMPtr_optimized( nsIDOMNode* aDOMNode, nsString* aResult )
+		// m112, w50/45
+	{
+//		if ( !aDOMNode || !aResult )
+//			return NS_ERROR_NULL_POINTER;
+
+		nsIDOMNode* temp;
+		nsresult status = aDOMNode->GetParentNode(&temp);
+		nsCOMPtr<nsIDOMNode> parent( dont_AddRef(temp) );
+		if ( parent )
+			parent->GetNodeName(*aResult);
+
+//		return status;
+	}
diff --git a/xpcom/tests/SizeTest04.cpp b/xpcom/tests/SizeTest04.cpp
new file mode 100644
index 000000000..e045f29f6
--- /dev/null
+++ b/xpcom/tests/SizeTest04.cpp
@@ -0,0 +1,68 @@
+// Test04.cpp
+
+#include "nsIDOMNode.h"
+#include "nsCOMPtr.h"
+
+NS_DEF_PTR(nsIDOMNode);
+
+	/*
+		Windows:
+			nsCOMPtr							 13
+			raw										 36
+
+		Macintosh:
+			nsCOMPtr							 36 bytes		(1.0000)
+			raw										120					(3.3333)	i.e., 333.33% bigger than nsCOMPtr
+	*/
+
+class Test04_Raw
+	{
+		public:
+			Test04_Raw();
+		 ~Test04_Raw();
+
+			void /*nsresult*/ SetNode( nsIDOMNode* newNode );
+
+		private:
+			nsIDOMNode* mNode;
+	};
+
+Test04_Raw::Test04_Raw()
+		: mNode(0)
+	{
+		// nothing else to do here
+	}
+
+Test04_Raw::~Test04_Raw()
+	{
+		NS_IF_RELEASE(mNode);
+	}
+
+void // nsresult
+Test04_Raw::SetNode( nsIDOMNode* newNode )
+		// m120, w36
+	{
+		NS_IF_ADDREF(newNode);
+		NS_IF_RELEASE(mNode);
+		mNode = newNode;
+
+//		return NS_OK;
+	}
+
+
+
+class Test04_nsCOMPtr
+	{
+		public:
+			void /*nsresult*/ SetNode( nsIDOMNode* newNode );
+
+		private:
+			nsCOMPtr<nsIDOMNode> mNode;
+	};
+
+void // nsresult
+Test04_nsCOMPtr::SetNode( nsIDOMNode* newNode )
+		// m36, w13/13
+	{
+		mNode = newNode;
+	}
diff --git a/xpcom/tests/SizeTest05.cpp b/xpcom/tests/SizeTest05.cpp
new file mode 100644
index 000000000..1307b1c26
--- /dev/null
+++ b/xpcom/tests/SizeTest05.cpp
@@ -0,0 +1,74 @@
+// Test05.cpp
+
+#include "nsIDOMNode.h"
+#include "nsCOMPtr.h"
+
+NS_DEF_PTR(nsIDOMNode);
+
+	/*
+		Windows:
+                        raw, nsCOMPtr           21 bytes
+
+		Macintosh:
+                        Raw, nsCOMPtr           64 bytes
+	*/
+
+class Test05_Raw
+	{
+		public:
+                        Test05_Raw();
+                 ~Test05_Raw();
+
+			void /*nsresult*/ GetNode( nsIDOMNode** aNode );
+
+		private:
+			nsIDOMNode* mNode;
+	};
+
+Test05_Raw::Test05_Raw()
+		: mNode(0)
+	{
+		// nothing else to do here
+	}
+
+Test05_Raw::~Test05_Raw()
+	{
+		NS_IF_RELEASE(mNode);
+	}
+
+void // nsresult
+Test05_Raw::GetNode( nsIDOMNode** aNode )
+		// m64, w21
+	{
+//		if ( !aNode )
+//			return NS_ERROR_NULL_POINTER;
+
+		*aNode = mNode;
+		NS_IF_ADDREF(*aNode);
+
+//		return NS_OK;
+	}
+
+
+
+class Test05_nsCOMPtr
+	{
+		public:
+			void /*nsresult*/ GetNode( nsIDOMNode** aNode );
+
+		private:
+			nsCOMPtr<nsIDOMNode> mNode;
+	};
+
+void // nsresult
+Test05_nsCOMPtr::GetNode( nsIDOMNode** aNode )
+		// m64, w21
+	{
+//		if ( !aNode )
+//			return NS_ERROR_NULL_POINTER;
+
+		*aNode = mNode;
+		NS_IF_ADDREF(*aNode);
+
+//		return NS_OK;
+	}
diff --git a/xpcom/tests/SizeTest06.cpp b/xpcom/tests/SizeTest06.cpp
new file mode 100644
index 000000000..67b57277d
--- /dev/null
+++ b/xpcom/tests/SizeTest06.cpp
@@ -0,0 +1,150 @@
+// Test06.cpp
+
+#include "nsPIDOMWindow.h"
+#include "nsIDocShell.h"
+#include "nsIBaseWindow.h"
+#include "nsCOMPtr.h"
+
+NS_DEF_PTR(nsPIDOMWindow);
+NS_DEF_PTR(nsIBaseWindow);
+
+  /*
+    Windows:
+      nsCOMPtr_optimized           176
+      nsCOMPtr_as_found            181
+      nsCOMPtr_optimized*          182
+      nsCOMPtr02*                  184
+      nsCOMPtr02                   187
+      nsCOMPtr02*                  188
+      nsCOMPtr03                   189
+      raw_optimized, nsCOMPtr00    191
+      nsCOMPtr00*                  199
+      nsCOMPtr_as_found*           201
+      raw                          214
+
+    Macintosh:
+      nsCOMPtr_optimized           300    (1.0000)
+      nsCOMPtr02                   320    (1.0667)  i.e., 6.67% bigger than nsCOMPtr_optimized
+      nsCOMPtr00                   328    (1.0933)
+      raw_optimized, nsCOMPtr03    332    (1.1067)
+      nsCOMPtr_as_found            344    (1.1467)
+      raw                          388    (1.2933)
+
+  */
+
+
+void // nsresult
+Test06_raw(nsIDOMWindow* aDOMWindow, nsIBaseWindow** aBaseWindow)
+    // m388, w214
+{
+//  if (!aDOMWindow)
+//    return NS_ERROR_NULL_POINTER;
+  nsPIDOMWindow* window = 0;
+  nsresult status = aDOMWindow->QueryInterface(NS_GET_IID(nsPIDOMWindow), (void**)&window);
+  nsIDocShell* docShell = 0;
+  if (window)
+    window->GetDocShell(&docShell);
+  nsIWebShell* rootWebShell = 0;
+  NS_IF_RELEASE(rootWebShell);
+  NS_IF_RELEASE(docShell);
+  NS_IF_RELEASE(window);
+//    return status;
+}
+
+void // nsresult
+Test06_raw_optimized(nsIDOMWindow* aDOMWindow, nsIBaseWindow** aBaseWindow)
+    // m332, w191
+{
+//  if (!aDOMWindow)
+//    return NS_ERROR_NULL_POINTER;
+  (*aBaseWindow) = 0;
+  nsPIDOMWindow* window;
+  nsresult status = aDOMWindow->QueryInterface(NS_GET_IID(nsPIDOMWindow), (void**)&window);
+  if (NS_SUCCEEDED(status)) {
+    nsIDocShell* docShell = 0;
+    window->GetDocShell(&docShell);
+    if (docShell) {
+      NS_RELEASE(docShell);
+    }
+    NS_RELEASE(window);
+  }
+//  return status;
+}
+
+void
+Test06_nsCOMPtr_as_found(nsIDOMWindow* aDOMWindow, nsCOMPtr<nsIBaseWindow>* aBaseWindow)
+    // m344, w181/201
+{
+//  if (!aDOMWindow)
+//    return;
+  nsCOMPtr<nsPIDOMWindow> window = do_QueryInterface(aDOMWindow);
+  nsCOMPtr<nsIDocShell> docShell;
+  if (window)
+    window->GetDocShell(getter_AddRefs(docShell));  
+}
+
+void // nsresult
+Test06_nsCOMPtr00(nsIDOMWindow* aDOMWindow, nsIBaseWindow** aBaseWindow)
+    // m328, w191/199
+{
+//  if (!aDOMWindow)
+//    return NS_ERROR_NULL_POINTER;
+  nsresult status;
+  nsCOMPtr<nsPIDOMWindow> window = do_QueryInterface(aDOMWindow, &status);
+  nsIDocShell* temp0 = 0;
+  if (window)
+    window->GetDocShell(&temp0);
+  nsCOMPtr<nsIDocShell> docShell = dont_AddRef(temp0);
+  (*aBaseWindow) = 0;
+//    return status;
+}
+
+void // nsresult
+Test06_nsCOMPtr_optimized(nsIDOMWindow* aDOMWindow, nsCOMPtr<nsIBaseWindow>* aBaseWindow)
+    // m300, w176/182
+{
+//    if (!aDOMWindow)
+//      return NS_ERROR_NULL_POINTER;
+  nsresult status;
+  nsCOMPtr<nsPIDOMWindow> window = do_QueryInterface(aDOMWindow, &status);
+  nsIDocShell* temp0 = 0;
+  if (window)
+    window->GetDocShell(&temp0);
+  (*aBaseWindow) = do_QueryInterface(nullptr, &status);
+//    return status;
+}
+
+void // nsresult
+Test06_nsCOMPtr02(nsIDOMWindow* aDOMWindow, nsIBaseWindow** aBaseWindow)
+    // m320, w187/184
+{
+//    if (!aDOMWindow)
+//      return NS_ERROR_NULL_POINTER;
+  (*aBaseWindow) = 0;
+  nsresult status;
+  nsCOMPtr<nsPIDOMWindow> window = do_QueryInterface(aDOMWindow, &status);
+  if (window) {
+    nsIDocShell* temp0;
+    window->GetDocShell(&temp0);
+  }
+//    return status;
+}
+
+void // nsresult
+Test06_nsCOMPtr03(nsIDOMWindow* aDOMWindow, nsCOMPtr<nsIBaseWindow>* aBaseWindow)
+    // m332, w189/188
+{
+//    if (!aDOMWindow)
+//      return NS_ERROR_NULL_POINTER;
+  (*aBaseWindow) = 0;
+  nsresult status;
+  nsCOMPtr<nsPIDOMWindow> window = do_QueryInterface(aDOMWindow, &status);
+  if (window) {
+    nsIDocShell* temp0;
+    window->GetDocShell(&temp0);
+    nsCOMPtr<nsIDocShell> docShell = dont_AddRef(temp0);
+    if (docShell) {
+    }
+  }
+//    return status;
+}
diff --git a/xpcom/tests/TestArguments.cpp b/xpcom/tests/TestArguments.cpp
new file mode 100644
index 000000000..a9a9a258b
--- /dev/null
+++ b/xpcom/tests/TestArguments.cpp
@@ -0,0 +1,25 @@
+#include <string.h>
+
+int main(int argc, char* argv[]) {
+  if (argc != 9)
+      return -1;
+
+  if (strcmp("mozilla", argv[1]) != 0)
+      return 1;
+  if (strcmp("firefox", argv[2]) != 0)
+      return 2;
+  if (strcmp("thunderbird", argv[3]) != 0)
+      return 3;
+  if (strcmp("seamonkey", argv[4]) != 0)
+      return 4;
+  if (strcmp("foo", argv[5]) != 0)
+      return 5;
+  if (strcmp("bar", argv[6]) != 0)
+      return 6;
+  if (strcmp("argument with spaces", argv[7]) != 0)
+      return 7;
+  if (strcmp("\"argument with quotes\"", argv[8]) != 0)
+      return 8;
+  
+  return 0;
+} 
diff --git a/xpcom/tests/TestBlockingProcess.cpp b/xpcom/tests/TestBlockingProcess.cpp
new file mode 100644
index 000000000..9526934c1
--- /dev/null
+++ b/xpcom/tests/TestBlockingProcess.cpp
@@ -0,0 +1,8 @@
+#include <stdio.h>
+
+int main()
+{
+  char tmp;
+  fread(&tmp, sizeof(tmp), 1, stdin);
+  return 0;
+}
diff --git a/xpcom/tests/TestHarness.h b/xpcom/tests/TestHarness.h
new file mode 100644
index 000000000..753e0233a
--- /dev/null
+++ b/xpcom/tests/TestHarness.h
@@ -0,0 +1,292 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Test harness for XPCOM objects, providing a scoped XPCOM initializer,
+ * nsCOMPtr, nsRefPtr, do_CreateInstance, do_GetService, ns(Auto|C|)String,
+ * and stdio.h/stdlib.h.
+ */
+
+#ifndef TestHarness_h__
+#define TestHarness_h__
+
+#include "mozilla/ArrayUtils.h"
+
+#include "prenv.h"
+#include "nsComponentManagerUtils.h"
+#include "nsServiceManagerUtils.h"
+#include "nsCOMPtr.h"
+#include "nsAutoPtr.h"
+#include "nsStringGlue.h"
+#include "nsAppDirectoryServiceDefs.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsDirectoryServiceUtils.h"
+#include "nsIDirectoryService.h"
+#include "nsIFile.h"
+#include "nsIProperties.h"
+#include "nsIObserverService.h"
+#include "nsXULAppAPI.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+
+static uint32_t gFailCount = 0;
+
+/**
+ * Prints the given failure message and arguments using printf, prepending
+ * "TEST-UNEXPECTED-FAIL " for the benefit of the test harness and
+ * appending "\n" to eliminate having to type it at each call site.
+ */
+void fail(const char* msg, ...)
+{
+  va_list ap;
+
+  printf("TEST-UNEXPECTED-FAIL | ");
+
+  va_start(ap, msg);
+  vprintf(msg, ap);
+  va_end(ap);
+
+  putchar('\n');
+  ++gFailCount;
+}
+
+/**
+ * Prints the given success message and arguments using printf, prepending
+ * "TEST-PASS " for the benefit of the test harness and
+ * appending "\n" to eliminate having to type it at each call site.
+ */
+void passed(const char* msg, ...)
+{
+  va_list ap;
+
+  printf("TEST-PASS | ");
+
+  va_start(ap, msg);
+  vprintf(msg, ap);
+  va_end(ap);
+
+  putchar('\n');
+}
+
+//-----------------------------------------------------------------------------
+
+class ScopedXPCOM : public nsIDirectoryServiceProvider2
+{
+  public:
+    NS_DECL_ISUPPORTS
+
+    explicit ScopedXPCOM(const char* testName,
+                         nsIDirectoryServiceProvider *dirSvcProvider = nullptr)
+    : mDirSvcProvider(dirSvcProvider)
+    {
+      mTestName = testName;
+      printf("Running %s tests...\n", mTestName);
+
+      nsresult rv = NS_InitXPCOM2(&mServMgr, nullptr, this);
+      if (NS_FAILED(rv))
+      {
+        fail("NS_InitXPCOM2 returned failure code 0x%x", rv);
+        mServMgr = nullptr;
+        return;
+      }
+    }
+
+    ~ScopedXPCOM()
+    {
+      // If we created a profile directory, we need to remove it.
+      if (mProfD) {
+        nsCOMPtr<nsIObserverService> os =
+          do_GetService(NS_OBSERVERSERVICE_CONTRACTID);
+        MOZ_RELEASE_ASSERT(os);
+        MOZ_ALWAYS_SUCCEEDS(os->NotifyObservers(nullptr, "profile-change-net-teardown", nullptr));
+        MOZ_ALWAYS_SUCCEEDS(os->NotifyObservers(nullptr, "profile-change-teardown", nullptr));
+        MOZ_ALWAYS_SUCCEEDS(os->NotifyObservers(nullptr, "profile-before-change", nullptr));
+        MOZ_ALWAYS_SUCCEEDS(os->NotifyObservers(nullptr, "profile-before-change-qm", nullptr));
+        MOZ_ALWAYS_SUCCEEDS(os->NotifyObservers(nullptr, "profile-before-change-telemetry", nullptr));
+
+        if (NS_FAILED(mProfD->Remove(true))) {
+          NS_WARNING("Problem removing profile directory");
+        }
+
+        mProfD = nullptr;
+      }
+
+      if (mServMgr)
+      {
+        NS_RELEASE(mServMgr);
+        nsresult rv = NS_ShutdownXPCOM(nullptr);
+        if (NS_FAILED(rv))
+        {
+          fail("XPCOM shutdown failed with code 0x%x", rv);
+          exit(1);
+        }
+      }
+
+      printf("Finished running %s tests.\n", mTestName);
+    }
+
+    bool failed()
+    {
+      return mServMgr == nullptr;
+    }
+
+    already_AddRefed<nsIFile> GetProfileDirectory()
+    {
+      if (mProfD) {
+        nsCOMPtr<nsIFile> copy = mProfD;
+        return copy.forget();
+      }
+
+      // Create a unique temporary folder to use for this test.
+      // Note that runcppunittests.py will run tests with a temp
+      // directory as the cwd, so just put something under that.
+      nsCOMPtr<nsIFile> profD;
+      nsresult rv = NS_GetSpecialDirectory(NS_OS_CURRENT_PROCESS_DIR,
+                                           getter_AddRefs(profD));
+      NS_ENSURE_SUCCESS(rv, nullptr);
+
+      rv = profD->Append(NS_LITERAL_STRING("cpp-unit-profd"));
+      NS_ENSURE_SUCCESS(rv, nullptr);
+
+      rv = profD->CreateUnique(nsIFile::DIRECTORY_TYPE, 0755);
+      NS_ENSURE_SUCCESS(rv, nullptr);
+
+      mProfD = profD;
+      return profD.forget();
+    }
+
+    already_AddRefed<nsIFile> GetGREDirectory()
+    {
+      if (mGRED) {
+        nsCOMPtr<nsIFile> copy = mGRED;
+        return copy.forget();
+      }
+
+      char* env = PR_GetEnv("MOZ_XRE_DIR");
+      nsCOMPtr<nsIFile> greD;
+      if (env) {
+        NS_NewLocalFile(NS_ConvertUTF8toUTF16(env), false,
+                        getter_AddRefs(greD));
+      }
+
+      mGRED = greD;
+      return greD.forget();
+    }
+
+    already_AddRefed<nsIFile> GetGREBinDirectory()
+    {
+      if (mGREBinD) {
+        nsCOMPtr<nsIFile> copy = mGREBinD;
+        return copy.forget();
+      }
+
+      nsCOMPtr<nsIFile> greD = GetGREDirectory();
+      if (!greD) {
+        return greD.forget();
+      }
+      greD->Clone(getter_AddRefs(mGREBinD));
+
+#ifdef XP_MACOSX
+      nsAutoCString leafName;
+      mGREBinD->GetNativeLeafName(leafName);
+      if (leafName.Equals("Resources")) {
+        mGREBinD->SetNativeLeafName(NS_LITERAL_CSTRING("MacOS"));
+      }
+#endif
+
+      nsCOMPtr<nsIFile> copy = mGREBinD;
+      return copy.forget();
+    }
+
+    ////////////////////////////////////////////////////////////////////////////
+    //// nsIDirectoryServiceProvider
+
+    NS_IMETHOD GetFile(const char *aProperty, bool *_persistent,
+                       nsIFile **_result) override
+    {
+      // If we were supplied a directory service provider, ask it first.
+      if (mDirSvcProvider &&
+          NS_SUCCEEDED(mDirSvcProvider->GetFile(aProperty, _persistent,
+                                                _result))) {
+        return NS_OK;
+      }
+
+      // Otherwise, the test harness provides some directories automatically.
+      if (0 == strcmp(aProperty, NS_APP_USER_PROFILE_50_DIR) ||
+          0 == strcmp(aProperty, NS_APP_USER_PROFILE_LOCAL_50_DIR) ||
+          0 == strcmp(aProperty, NS_APP_PROFILE_LOCAL_DIR_STARTUP)) {
+        nsCOMPtr<nsIFile> profD = GetProfileDirectory();
+        NS_ENSURE_TRUE(profD, NS_ERROR_FAILURE);
+
+        nsCOMPtr<nsIFile> clone;
+        nsresult rv = profD->Clone(getter_AddRefs(clone));
+        NS_ENSURE_SUCCESS(rv, rv);
+
+        *_persistent = true;
+        clone.forget(_result);
+        return NS_OK;
+      } else if (0 == strcmp(aProperty, NS_GRE_DIR)) {
+        nsCOMPtr<nsIFile> greD = GetGREDirectory();
+        NS_ENSURE_TRUE(greD, NS_ERROR_FAILURE);
+
+        *_persistent = true;
+        greD.forget(_result);
+        return NS_OK;
+      } else if (0 == strcmp(aProperty, NS_GRE_BIN_DIR)) {
+        nsCOMPtr<nsIFile> greBinD = GetGREBinDirectory();
+        NS_ENSURE_TRUE(greBinD, NS_ERROR_FAILURE);
+
+        *_persistent = true;
+        greBinD.forget(_result);
+        return NS_OK;
+      }
+
+      return NS_ERROR_FAILURE;
+    }
+
+    ////////////////////////////////////////////////////////////////////////////
+    //// nsIDirectoryServiceProvider2
+
+    NS_IMETHOD GetFiles(const char *aProperty, nsISimpleEnumerator **_enum) override
+    {
+      // If we were supplied a directory service provider, ask it first.
+      nsCOMPtr<nsIDirectoryServiceProvider2> provider =
+        do_QueryInterface(mDirSvcProvider);
+      if (provider && NS_SUCCEEDED(provider->GetFiles(aProperty, _enum))) {
+        return NS_OK;
+      }
+
+     return NS_ERROR_FAILURE;
+   }
+
+  private:
+    const char* mTestName;
+    nsIServiceManager* mServMgr;
+    nsCOMPtr<nsIDirectoryServiceProvider> mDirSvcProvider;
+    nsCOMPtr<nsIFile> mProfD;
+    nsCOMPtr<nsIFile> mGRED;
+    nsCOMPtr<nsIFile> mGREBinD;
+};
+
+NS_IMPL_QUERY_INTERFACE(
+  ScopedXPCOM,
+  nsIDirectoryServiceProvider,
+  nsIDirectoryServiceProvider2
+)
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+ScopedXPCOM::AddRef()
+{
+  return 2;
+}
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+ScopedXPCOM::Release()
+{
+  return 1;
+}
+
+#endif  // TestHarness_h__
diff --git a/xpcom/tests/TestPRIntN.cpp b/xpcom/tests/TestPRIntN.cpp
new file mode 100644
index 000000000..afc155d70
--- /dev/null
+++ b/xpcom/tests/TestPRIntN.cpp
@@ -0,0 +1,33 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdint.h>
+#include "prtypes.h"
+
+// This test is NOT intended to be run.  It's a test to make sure
+// PRInt{N} matches int{N}_t. If they don't match, we should get a
+// compiler warning or error in main().
+
+static void
+ClearNSPRIntTypes(PRInt8 *a, PRInt16 *b, PRInt32 *c, PRInt64 *d)
+{
+  *a = 0; *b = 0; *c = 0; *d = 0;
+}
+
+static void
+ClearStdIntTypes(int8_t *w, int16_t *x, int32_t *y, int64_t *z)
+{
+  *w = 0; *x = 0; *y = 0; *z = 0;
+}
+
+int
+main()
+{
+  PRInt8 a; PRInt16 b; PRInt32 c; PRInt64 d;
+  int8_t w; int16_t x; int32_t y; int64_t z;
+
+  ClearNSPRIntTypes(&w, &x, &y, &z);
+  ClearStdIntTypes(&a, &b, &c, &d);
+  return 0;
+}
diff --git a/xpcom/tests/TestQuickReturn.cpp b/xpcom/tests/TestQuickReturn.cpp
new file mode 100644
index 000000000..d00771ba7
--- /dev/null
+++ b/xpcom/tests/TestQuickReturn.cpp
@@ -0,0 +1,8 @@
+#include <stdio.h>
+
+int main (int argc, char* argv[]) {
+  if (argc != 1)
+      return -1;
+
+  return 42;
+}
diff --git a/xpcom/tests/TestShutdown.cpp b/xpcom/tests/TestShutdown.cpp
new file mode 100644
index 000000000..177c83dbd
--- /dev/null
+++ b/xpcom/tests/TestShutdown.cpp
@@ -0,0 +1,41 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIServiceManager.h"
+
+// Gee this seems simple! It's for testing for memory leaks with Purify.
+
+void main(int argc, char* argv[])
+{
+    nsresult rv;
+    nsIServiceManager* servMgr;
+    rv = NS_InitXPCOM2(&servMgr, nullptr, nullptr);
+    NS_ASSERTION(NS_SUCCEEDED(rv), "NS_InitXPCOM failed");
+
+    // try loading a component and releasing it to see if it leaks
+    if (argc > 1 && argv[1] != nullptr) {
+        char* cidStr = argv[1];
+        nsISupports* obj = nullptr;
+        if (cidStr[0] == '{') {
+            nsCID cid;
+            cid.Parse(cidStr);
+            rv = CallCreateInstance(cid, &obj);
+        }
+        else {
+            // contractID case:
+            rv = CallCreateInstance(cidStr, &obj);
+        }
+        if (NS_SUCCEEDED(rv)) {
+            printf("Successfully created %s\n", cidStr);
+            NS_RELEASE(obj);
+        }
+        else {
+            printf("Failed to create %s (%x)\n", cidStr, rv);
+        }
+    }
+
+    rv = NS_ShutdownXPCOM(servMgr);
+    NS_ASSERTION(NS_SUCCEEDED(rv), "NS_ShutdownXPCOM failed");
+}
diff --git a/xpcom/tests/TestStackCrawl.cpp b/xpcom/tests/TestStackCrawl.cpp
new file mode 100644
index 000000000..e1fe37db7
--- /dev/null
+++ b/xpcom/tests/TestStackCrawl.cpp
@@ -0,0 +1,11 @@
+#include <stdio.h>
+
+#include "nsISupportsUtils.h"
+#include "nsTraceRefcnt.h"
+
+int main(int argc, char* argv[])
+{
+    nsTraceRefcnt::WalkTheStack(stdout);
+    return 0;
+}
+
diff --git a/xpcom/tests/TestStreamUtils.cpp b/xpcom/tests/TestStreamUtils.cpp
new file mode 100644
index 000000000..72640474f
--- /dev/null
+++ b/xpcom/tests/TestStreamUtils.cpp
@@ -0,0 +1,74 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include "nsIPipe.h"
+#include "nsStreamUtils.h"
+#include "nsString.h"
+#include "nsCOMPtr.h"
+
+//----
+
+static bool test_consume_stream() {
+  const char kData[] =
+      "Get your facts first, and then you can distort them as much as you "
+      "please.";
+
+  nsCOMPtr<nsIInputStream> input;
+  nsCOMPtr<nsIOutputStream> output;
+  NS_NewPipe(getter_AddRefs(input),
+             getter_AddRefs(output),
+             10, UINT32_MAX);
+  if (!input || !output)
+    return false;
+
+  uint32_t n = 0;
+  output->Write(kData, sizeof(kData) - 1, &n);
+  if (n != (sizeof(kData) - 1))
+    return false;
+  output = nullptr;  // close output
+
+  nsCString buf;
+  if (NS_FAILED(NS_ConsumeStream(input, UINT32_MAX, buf)))
+    return false;
+
+  if (!buf.Equals(kData))
+    return false;
+
+  return true; 
+}
+
+//----
+
+typedef bool (*TestFunc)();
+#define DECL_TEST(name) { #name, name }
+
+static const struct Test {
+  const char* name;
+  TestFunc    func;
+} tests[] = {
+  DECL_TEST(test_consume_stream),
+  { nullptr, nullptr }
+};
+
+int main(int argc, char **argv) {
+  int count = 1;
+  if (argc > 1)
+    count = atoi(argv[1]);
+
+  if (NS_FAILED(NS_InitXPCOM2(nullptr, nullptr, nullptr)))
+    return -1;
+
+  while (count--) {
+    for (const Test* t = tests; t->name != nullptr; ++t) {
+      printf("%25s : %s\n", t->name, t->func() ? "SUCCESS" : "FAILURE");
+    }
+  }
+  
+  NS_ShutdownXPCOM(nullptr);
+  return 0;
+}
diff --git a/xpcom/tests/TestUnicodeArguments.cpp b/xpcom/tests/TestUnicodeArguments.cpp
new file mode 100644
index 000000000..35d80a7f4
--- /dev/null
+++ b/xpcom/tests/TestUnicodeArguments.cpp
@@ -0,0 +1,77 @@
+/**
+ * On Windows, a Unicode argument is passed as UTF-16 using ShellExecuteExW.
+ * On other platforms, it is passed as UTF-8
+ */
+
+static const int args_length = 4;
+#if defined(XP_WIN) && defined(_MSC_VER)
+#define _UNICODE
+#include <tchar.h>
+#include <stdio.h>
+
+static const _TCHAR* expected_utf16[args_length] = {
+  // Latin-1
+  L"M\xF8z\xEEll\xE5",
+  // Cyrillic
+  L"\x41C\x43E\x437\x438\x43B\x43B\x430",
+  // Bengali
+  L"\x9AE\x9CB\x99C\x9BF\x9B2\x9BE",
+  // Cuneiform
+  L"\xD808\xDE2C\xD808\xDF63\xD808\xDDB7"
+};
+
+int wmain(int argc, _TCHAR* argv[]) {
+  printf("argc = %d\n", argc);
+
+  if (argc != args_length + 1)
+    return -1;
+
+  for (int i = 1; i < argc; ++i) {
+    printf("expected[%d]: ", i - 1);
+    for (size_t j = 0; j < _tcslen(expected_utf16[i - 1]); ++j) {
+      printf("%x ", *(expected_utf16[i - 1] + j));
+    }
+    printf("\n");
+
+    printf("argv[%d]: ", i);
+    for (size_t j = 0; j < _tcslen(argv[i]); ++j) {
+      printf("%x ", *(argv[i] + j));
+    }
+    printf("\n");
+
+    if (_tcscmp(expected_utf16[i - 1], argv[i])) {
+      return i;
+    }
+  }
+
+  return 0;
+}
+#else
+#include <string.h>
+#include <stdio.h>
+
+static const char* expected_utf8[args_length] = {
+  // Latin-1
+  "M\xC3\xB8z\xC3\xAEll\xC3\xA5",
+  // Cyrillic
+  "\xD0\x9C\xD0\xBE\xD0\xB7\xD0\xB8\xD0\xBB\xD0\xBB\xD0\xB0",
+  // Bengali
+  "\xE0\xA6\xAE\xE0\xA7\x8B\xE0\xA6\x9C\xE0\xA6\xBF\xE0\xA6\xB2\xE0\xA6\xBE",
+  // Cuneiform
+  "\xF0\x92\x88\xAC\xF0\x92\x8D\xA3\xF0\x92\x86\xB7"
+};
+
+int main(int argc, char* argv[]) {
+  if (argc != args_length + 1)
+    return -1;
+
+  for (int i = 1; i < argc; ++i) {
+    printf("argv[%d] = %s; expected = %s\n", i, argv[i], expected_utf8[i - 1]);
+    if (strcmp(expected_utf8[i - 1], argv[i])) {
+      return i;
+    }
+  }
+
+  return 0;
+}
+#endif
diff --git a/xpcom/tests/TestWinReg.js b/xpcom/tests/TestWinReg.js
new file mode 100644
index 000000000..5bde37900
--- /dev/null
+++ b/xpcom/tests/TestWinReg.js
@@ -0,0 +1,57 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * This script is intended to be run using xpcshell
+ */
+
+const nsIWindowsRegKey = Components.interfaces.nsIWindowsRegKey;
+const BASE_PATH = "SOFTWARE\\Mozilla\\Firefox";
+
+function idump(indent, str)
+{
+  for (var j = 0; j < indent; ++j)
+    dump(" ");
+  dump(str);
+}
+
+function list_values(indent, key) {
+  idump(indent, "{\n");
+  var count = key.valueCount;
+  for (var i = 0; i < count; ++i) {
+    var vn = key.getValueName(i);
+    var val = "";
+    if (key.getValueType(vn) == nsIWindowsRegKey.TYPE_STRING) {
+      val = key.readStringValue(vn);
+    }
+    if (vn == "") 
+      idump(indent + 1, "(Default): \"" + val + "\"\n");
+    else
+      idump(indent + 1, vn + ": \"" + val + "\"\n");
+  } 
+  idump(indent, "}\n");
+}
+
+function list_children(indent, key) {
+  list_values(indent, key);
+
+  var count = key.childCount;
+  for (var i = 0; i < count; ++i) {
+    var cn = key.getChildName(i);
+    idump(indent, "[" + cn + "]\n");
+    list_children(indent + 1, key.openChild(cn, nsIWindowsRegKey.ACCESS_READ));
+  }
+}
+
+// enumerate everything under BASE_PATH
+var key = Components.classes["@mozilla.org/windows-registry-key;1"].
+    createInstance(nsIWindowsRegKey);
+key.open(nsIWindowsRegKey.ROOT_KEY_LOCAL_MACHINE, BASE_PATH,
+         nsIWindowsRegKey.ACCESS_READ);
+list_children(1, key);
+
+key.close();
+key.open(nsIWindowsRegKey.ROOT_KEY_CURRENT_USER, BASE_PATH,
+         nsIWindowsRegKey.ACCESS_READ);
+list_children(1, key);
diff --git a/xpcom/tests/TestingAtomList.h b/xpcom/tests/TestingAtomList.h
new file mode 100644
index 000000000..ffeada605
--- /dev/null
+++ b/xpcom/tests/TestingAtomList.h
@@ -0,0 +1,6 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+TESTING_ATOM(foo, "foo")
+TESTING_ATOM(bar, "bar")
diff --git a/xpcom/tests/bug656331_component/TestComponent.cpp b/xpcom/tests/bug656331_component/TestComponent.cpp
new file mode 100644
index 000000000..987d21451
--- /dev/null
+++ b/xpcom/tests/bug656331_component/TestComponent.cpp
@@ -0,0 +1,32 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ModuleUtils.h"
+
+// f18fb09b-28b4-4435-bc5b-8027f18df743
+#define NS_TESTING_CID \
+{ 0xf18fb09b, 0x28b4, 0x4435, \
+  { 0xbc, 0x5b, 0x80, 0x27, 0xf1, 0x8d, 0xf7, 0x43 } }
+
+NS_DEFINE_NAMED_CID(NS_TESTING_CID);
+
+static nsresult
+DummyConstructorFunc(nsISupports* aOuter, const nsIID& aIID, void** aResult)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+static const mozilla::Module::CIDEntry kTestCIDs[] = {
+  { &kNS_TESTING_CID, false, nullptr, DummyConstructorFunc },
+  { nullptr }
+};
+
+static const mozilla::Module kTestModule = {
+  3, /* faking mozilla::Module::kVersion with a value that will never be used */
+  kTestCIDs
+};
+
+NSMODULE_DEFN(dummy) = &kTestModule;
diff --git a/xpcom/tests/bug656331_component/bug656331.manifest b/xpcom/tests/bug656331_component/bug656331.manifest
new file mode 100644
index 000000000..fb1991a56
--- /dev/null
+++ b/xpcom/tests/bug656331_component/bug656331.manifest
@@ -0,0 +1,2 @@
+#filter substitution
+binary-component @LIBRARY_FILENAME@
diff --git a/xpcom/tests/bug656331_component/moz.build b/xpcom/tests/bug656331_component/moz.build
new file mode 100644
index 000000000..e986f3de0
--- /dev/null
+++ b/xpcom/tests/bug656331_component/moz.build
@@ -0,0 +1,26 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+FINAL_TARGET = '_tests/xpcshell/xpcom/tests/unit'
+EXTRA_PP_COMPONENTS += [
+    'bug656331.manifest',
+]
+
+SOURCES += [
+    'TestComponent.cpp',
+]
+
+XPCOMBinaryComponent('test656331')
+
+DEFINES['LIBRARY_FILENAME'] = '%s%s%s' % (
+    CONFIG['DLL_PREFIX'],
+    LIBRARY_NAME,
+    CONFIG['DLL_SUFFIX']
+)
+
+# Need to link with CoreFoundation on Mac
+if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa':
+    OS_LIBS += CONFIG['TK_LIBS']
diff --git a/xpcom/tests/component/TestComponent.cpp b/xpcom/tests/component/TestComponent.cpp
new file mode 100644
index 000000000..85b8860ac
--- /dev/null
+++ b/xpcom/tests/component/TestComponent.cpp
@@ -0,0 +1,44 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ModuleUtils.h"
+
+#define NS_TESTING_CID \
+{ 0x335fb596, 0xe52d, 0x418f, \
+  { 0xb0, 0x1c, 0x1b, 0xf1, 0x6c, 0xe5, 0xe7, 0xe4 } }
+#define NS_NONEXISTENT_CID \
+{ 0x1e61fb15, 0xead4, 0x45cd, \
+  { 0x80, 0x13, 0x40, 0x99, 0xa7, 0x10, 0xa2, 0xfa } }
+
+NS_DEFINE_NAMED_CID(NS_TESTING_CID);
+NS_DEFINE_NAMED_CID(NS_NONEXISTENT_CID);
+
+static nsresult
+DummyConstructorFunc(nsISupports* aOuter, const nsIID& aIID, void** aResult)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+static const mozilla::Module::CIDEntry kTestCIDs[] = {
+  { &kNS_TESTING_CID, false, nullptr, DummyConstructorFunc },
+  { &kNS_TESTING_CID, false, nullptr, DummyConstructorFunc },
+  { nullptr }
+};
+
+static const mozilla::Module::ContractIDEntry kTestContractIDs[] = {
+  { "@testing/foo", &kNS_NONEXISTENT_CID },
+  { nullptr }
+};
+
+static const mozilla::Module kTestModule = {
+  mozilla::Module::kVersion,
+  kTestCIDs,
+  kTestContractIDs
+};
+
+NSMODULE_DEFN(dummy) = &kTestModule;
+
+  
diff --git a/xpcom/tests/component/moz.build b/xpcom/tests/component/moz.build
new file mode 100644
index 000000000..62e88502c
--- /dev/null
+++ b/xpcom/tests/component/moz.build
@@ -0,0 +1,26 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+FINAL_TARGET = '_tests/xpcshell/xpcom/tests/unit'
+EXTRA_PP_COMPONENTS += [
+    'testcomponent.manifest',
+]
+
+SOURCES += [
+    'TestComponent.cpp',
+]
+
+XPCOMBinaryComponent('testcomponent')
+
+DEFINES['LIBRARY_FILENAME'] = '%s%s%s' % (
+    CONFIG['DLL_PREFIX'],
+    LIBRARY_NAME,
+    CONFIG['DLL_SUFFIX']
+)
+
+# Need to link with CoreFoundation on Mac
+if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa':
+    OS_LIBS += CONFIG['TK_LIBS']
diff --git a/xpcom/tests/component/testcomponent.manifest b/xpcom/tests/component/testcomponent.manifest
new file mode 100644
index 000000000..a570e4c18
--- /dev/null
+++ b/xpcom/tests/component/testcomponent.manifest
@@ -0,0 +1,4 @@
+#filter substitution
+binary-component @LIBRARY_FILENAME@
+binary-component @LIBRARY_FILENAME@
+binary-component @LIBRARY_FILENAME@
diff --git a/xpcom/tests/component_no_aslr/Makefile.in b/xpcom/tests/component_no_aslr/Makefile.in
new file mode 100644
index 000000000..f08d6ad8a
--- /dev/null
+++ b/xpcom/tests/component_no_aslr/Makefile.in
@@ -0,0 +1,8 @@
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include $(topsrcdir)/config/rules.mk
+
+LDFLAGS := $(filter-out -DYNAMICBASE,$(LDFLAGS)) -DYNAMICBASE:NO
diff --git a/xpcom/tests/component_no_aslr/TestComponent.cpp b/xpcom/tests/component_no_aslr/TestComponent.cpp
new file mode 100644
index 000000000..6fbfd316a
--- /dev/null
+++ b/xpcom/tests/component_no_aslr/TestComponent.cpp
@@ -0,0 +1,33 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ModuleUtils.h"
+
+#define NS_TESTING_CID \
+{ 0x335fb596, 0xe52d, 0x418f, \
+  { 0xb0, 0x1c, 0x1b, 0xf1, 0x6c, 0xe5, 0xe7, 0xe4 } }
+
+NS_DEFINE_NAMED_CID(NS_TESTING_CID);
+
+static nsresult
+DummyConstructorFunc(nsISupports* aOuter, const nsIID& aIID, void** aResult)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+static const mozilla::Module::CIDEntry kTestCIDs[] = {
+  { &kNS_TESTING_CID, false, nullptr, DummyConstructorFunc },
+  { nullptr }
+};
+
+static const mozilla::Module kTestModule = {
+  mozilla::Module::kVersion,
+  kTestCIDs
+};
+
+NSMODULE_DEFN(dummy) = &kTestModule;
+
+  
diff --git a/xpcom/tests/component_no_aslr/moz.build b/xpcom/tests/component_no_aslr/moz.build
new file mode 100644
index 000000000..45e69c105
--- /dev/null
+++ b/xpcom/tests/component_no_aslr/moz.build
@@ -0,0 +1,26 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+FINAL_TARGET = '_tests/xpcshell/xpcom/tests/unit'
+EXTRA_PP_COMPONENTS += [
+    'testcompnoaslr.manifest',
+]
+
+SOURCES += [
+    'TestComponent.cpp',
+]
+
+XPCOMBinaryComponent('testcompnoaslr')
+
+DEFINES['LIBRARY_FILENAME'] = '%s%s%s' % (
+    CONFIG['DLL_PREFIX'],
+    LIBRARY_NAME,
+    CONFIG['DLL_SUFFIX']
+)
+
+# Need to link with CoreFoundation on Mac
+if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa':
+    OS_LIBS += CONFIG['TK_LIBS']
diff --git a/xpcom/tests/component_no_aslr/testcompnoaslr.manifest b/xpcom/tests/component_no_aslr/testcompnoaslr.manifest
new file mode 100644
index 000000000..fb1991a56
--- /dev/null
+++ b/xpcom/tests/component_no_aslr/testcompnoaslr.manifest
@@ -0,0 +1,2 @@
+#filter substitution
+binary-component @LIBRARY_FILENAME@
diff --git a/xpcom/tests/external/TestMinStringAPI.cpp b/xpcom/tests/external/TestMinStringAPI.cpp
new file mode 100644
index 000000000..28bc0b1c1
--- /dev/null
+++ b/xpcom/tests/external/TestMinStringAPI.cpp
@@ -0,0 +1,1009 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "nsStringAPI.h"
+#include "nsXPCOM.h"
+#include "nsMemory.h"
+
+static const char kAsciiData[] = "Hello World";
+
+static const char16_t kUnicodeData[] =
+  {'H','e','l','l','o',' ','W','o','r','l','d','\0'};
+
+static bool test_basic_1()
+  {
+    nsCStringContainer s;
+    NS_CStringContainerInit(s);
+
+    const char *ptr;
+    uint32_t len;
+    char *clone;
+
+    NS_CStringGetData(s, &ptr);
+    if (ptr == nullptr || *ptr != '\0')
+      {
+        NS_ERROR("unexpected result");
+        return false;
+      }
+
+    NS_CStringSetData(s, kAsciiData, UINT32_MAX);
+    len = NS_CStringGetData(s, &ptr);
+    if (ptr == nullptr || strcmp(ptr, kAsciiData) != 0)
+      {
+        NS_ERROR("unexpected result");
+        return false;
+      }
+    if (len != sizeof(kAsciiData)-1)
+      {
+        NS_ERROR("unexpected result");
+        return false;
+      }
+
+    clone = NS_CStringCloneData(s);
+    if (ptr == nullptr || strcmp(ptr, kAsciiData) != 0)
+      {
+        NS_ERROR("unexpected result");
+        return false;
+      }
+    free(clone);
+
+    nsCStringContainer temp;
+    NS_CStringContainerInit(temp);
+    NS_CStringCopy(temp, s);
+
+    len = NS_CStringGetData(temp, &ptr);
+    if (ptr == nullptr || strcmp(ptr, kAsciiData) != 0)
+      {
+        NS_ERROR("unexpected result");
+        return false;
+      }
+    if (len != sizeof(kAsciiData)-1)
+      {
+        NS_ERROR("unexpected result");
+        return false;
+      }
+
+    NS_CStringContainerFinish(temp);
+
+    NS_CStringContainerFinish(s);
+    return true;
+  }
+
+static bool test_basic_2()
+  {
+    nsStringContainer s;
+    NS_StringContainerInit(s);
+
+    const char16_t *ptr;
+    uint32_t len;
+    char16_t *clone;
+
+    NS_StringGetData(s, &ptr);
+    if (ptr == nullptr || *ptr != '\0')
+      {
+        NS_ERROR("unexpected result");
+        return false;
+      }
+
+    NS_StringSetData(s, kUnicodeData, UINT32_MAX);
+    len = NS_StringGetData(s, &ptr);
+    if (len != sizeof(kUnicodeData)/2 - 1)
+      {
+        NS_ERROR("unexpected result");
+        return false;
+      }
+    if (ptr == nullptr || memcmp(ptr, kUnicodeData, sizeof(kUnicodeData)) != 0)
+      {
+        NS_ERROR("unexpected result");
+        return false;
+      }
+
+    clone = NS_StringCloneData(s);
+    if (ptr == nullptr || memcmp(ptr, kUnicodeData, sizeof(kUnicodeData)) != 0)
+      {
+        NS_ERROR("unexpected result");
+        return false;
+      }
+    free(clone);
+
+    nsStringContainer temp;
+    NS_StringContainerInit(temp);
+    NS_StringCopy(temp, s);
+
+    len = NS_StringGetData(temp, &ptr);
+    if (len != sizeof(kUnicodeData)/2 - 1)
+      {
+        NS_ERROR("unexpected result");
+        return false;
+      }
+    if (ptr == nullptr || memcmp(ptr, kUnicodeData, sizeof(kUnicodeData)) != 0)
+      {
+        NS_ERROR("unexpected result");
+        return false;
+      }
+
+    NS_StringContainerFinish(temp);
+
+    NS_StringContainerFinish(s);
+
+    return true;
+  }
+
+static bool test_convert()
+  {
+    nsStringContainer s;
+    NS_StringContainerInit(s);
+    NS_StringSetData(s, kUnicodeData, sizeof(kUnicodeData)/2 - 1);
+
+    nsCStringContainer temp;
+    NS_CStringContainerInit(temp);
+
+    const char *data;
+
+    NS_UTF16ToCString(s, NS_CSTRING_ENCODING_ASCII, temp);
+    NS_CStringGetData(temp, &data);
+    if (strcmp(data, kAsciiData) != 0)
+      return false;
+
+    NS_UTF16ToCString(s, NS_CSTRING_ENCODING_UTF8, temp);
+    NS_CStringGetData(temp, &data);
+    if (strcmp(data, kAsciiData) != 0)
+      return false;
+
+    NS_CStringContainerFinish(temp);
+
+    NS_StringContainerFinish(s);
+    return true;
+  }
+
+static bool test_append()
+  {
+    nsCStringContainer s;
+    NS_CStringContainerInit(s);
+
+    NS_CStringSetData(s, "foo");
+    NS_CStringAppendData(s, "bar");
+
+    NS_CStringContainerFinish(s);
+    return true;
+  }
+
+// Replace all occurrences of |matchVal| with |newVal|
+static void ReplaceSubstring( nsACString& str,
+                              const nsACString& matchVal,
+                              const nsACString& newVal )
+  {
+    const char* sp;
+    const char* mp;
+    const char* np;
+    uint32_t sl = NS_CStringGetData(str, &sp);
+    uint32_t ml = NS_CStringGetData(matchVal, &mp);
+    uint32_t nl = NS_CStringGetData(newVal, &np);
+
+    for (const char* iter = sp; iter <= sp + sl - ml; ++iter)
+      {
+        if (memcmp(iter, mp, ml) == 0)
+          {
+            uint32_t offset = iter - sp;
+
+            NS_CStringSetDataRange(str, offset, ml, np, nl);
+
+            sl = NS_CStringGetData(str, &sp);
+
+            iter = sp + offset + nl - 1;
+          }
+      }
+  }
+
+static bool test_replace_driver(const char *strVal,
+                                  const char *matchVal,
+                                  const char *newVal,
+                                  const char *finalVal)
+  {
+    nsCStringContainer a;
+    NS_CStringContainerInit(a);
+    NS_CStringSetData(a, strVal);
+
+    nsCStringContainer b;
+    NS_CStringContainerInit(b);
+    NS_CStringSetData(b, matchVal);
+
+    nsCStringContainer c;
+    NS_CStringContainerInit(c);
+    NS_CStringSetData(c, newVal);
+
+    ReplaceSubstring(a, b, c);
+
+    const char *data;
+    NS_CStringGetData(a, &data);
+    if (strcmp(data, finalVal) != 0)
+      return false;
+
+    NS_CStringContainerFinish(c);
+    NS_CStringContainerFinish(b);
+    NS_CStringContainerFinish(a);
+    return true;
+  }
+
+static bool test_replace()
+  {
+    bool rv;
+
+    rv = test_replace_driver("hello world, hello again!",
+                             "hello",
+                             "goodbye",
+                             "goodbye world, goodbye again!");
+    if (!rv)
+      return rv;
+
+    rv = test_replace_driver("foofoofoofoo!",
+                             "foo",
+                             "bar",
+                             "barbarbarbar!");
+    if (!rv)
+      return rv;
+
+    rv = test_replace_driver("foo bar systems",
+                             "xyz",
+                             "crazy",
+                             "foo bar systems");
+    if (!rv)
+      return rv;
+
+    rv = test_replace_driver("oh",
+                             "xyz",
+                             "crazy",
+                             "oh");
+    if (!rv)
+      return rv;
+
+    return true;
+  }
+
+static const char* kWhitespace="\f\t\r\n ";
+
+static void
+CompressWhitespace(nsACString &str)
+  {
+    const char *p;
+    int32_t i, len = (int32_t) NS_CStringGetData(str, &p);
+
+    // trim leading whitespace
+
+    for (i=0; i<len; ++i)
+      {
+        if (!strchr(kWhitespace, (char) p[i]))
+          break;
+      }
+
+    if (i>0)
+      {
+        NS_CStringCutData(str, 0, i);
+        len = (int32_t) NS_CStringGetData(str, &p);
+      }
+
+    // trim trailing whitespace
+
+    for (i=len-1; i>=0; --i)
+      {
+        if (!strchr(kWhitespace, (char) p[i]))
+          break;
+      }
+
+    if (++i < len)
+      NS_CStringCutData(str, i, len - i);
+  }
+
+static bool test_compress_ws()
+  {
+    nsCStringContainer s;
+    NS_CStringContainerInit(s);
+    NS_CStringSetData(s, " \thello world\r  \n");
+    CompressWhitespace(s);
+    const char *d;
+    NS_CStringGetData(s, &d);
+    bool rv = !strcmp(d, "hello world");
+    if (!rv)
+      printf("=> \"%s\"\n", d);
+    NS_CStringContainerFinish(s);
+    return rv;
+  }
+
+static bool test_depend()
+  {
+    static const char kData[] = "hello world";
+
+    nsCStringContainer s;
+    NS_ENSURE_SUCCESS(
+        NS_CStringContainerInit2(s, kData, sizeof(kData)-1,
+                                 NS_CSTRING_CONTAINER_INIT_DEPEND),
+        false);
+
+    const char *sd;
+    NS_CStringGetData(s, &sd);
+
+    bool rv = (sd == kData);
+    NS_CStringContainerFinish(s);
+    return rv;
+  }
+
+static bool test_depend_sub()
+  {
+    static const char kData[] = "hello world";
+
+    nsCStringContainer s;
+    NS_ENSURE_SUCCESS(
+        NS_CStringContainerInit2(s, kData, sizeof(kData)-1,
+                                 NS_CSTRING_CONTAINER_INIT_DEPEND |
+                                 NS_CSTRING_CONTAINER_INIT_SUBSTRING),
+        false);
+
+    bool terminated;
+    const char *sd;
+    uint32_t len = NS_CStringGetData(s, &sd, &terminated);
+
+    bool rv = (sd == kData && len == sizeof(kData)-1 && !terminated);
+    NS_CStringContainerFinish(s);
+    return rv;
+  }
+
+static bool test_adopt()
+  {
+    static const char kData[] = "hello world";
+
+    char *data = (char *) nsMemory::Clone(kData, sizeof(kData));
+    if (!data)
+      return false;
+
+    nsCStringContainer s;
+    NS_ENSURE_SUCCESS(
+        NS_CStringContainerInit2(s, data, UINT32_MAX,
+                                 NS_CSTRING_CONTAINER_INIT_ADOPT),
+        false); // leaks data on failure *shrug*
+
+    const char *sd;
+    NS_CStringGetData(s, &sd);
+
+    bool rv = (sd == data);
+    NS_CStringContainerFinish(s);
+    return rv;
+  }
+
+static bool test_adopt_sub()
+  {
+    static const char kData[] = "hello world";
+
+    char *data = (char *) nsMemory::Clone(kData, sizeof(kData)-1);
+    if (!data)
+      return false;
+
+    nsCStringContainer s;
+    NS_ENSURE_SUCCESS(
+        NS_CStringContainerInit2(s, data, sizeof(kData)-1,
+                                 NS_CSTRING_CONTAINER_INIT_ADOPT |
+                                 NS_CSTRING_CONTAINER_INIT_SUBSTRING),
+        false); // leaks data on failure *shrug*
+
+    bool terminated;
+    const char *sd;
+    uint32_t len = NS_CStringGetData(s, &sd, &terminated);
+
+    bool rv = (sd == data && len == sizeof(kData)-1 && !terminated);
+    NS_CStringContainerFinish(s);
+    return rv;
+  }
+
+static bool test_mutation()
+  {
+    nsCStringContainer s;
+    NS_CStringContainerInit(s);
+
+    const char kText[] = "Every good boy does fine.";
+
+    char *buf;
+    uint32_t len = NS_CStringGetMutableData(s, sizeof(kText) - 1, &buf);
+    if (!buf || len != sizeof(kText) - 1)
+      return false;
+    memcpy(buf, kText, sizeof(kText));
+
+    const char *data;
+    NS_CStringGetData(s, &data);
+    if (strcmp(data, kText) != 0)
+      return false;
+
+    uint32_t newLen = len + 1;
+    len = NS_CStringGetMutableData(s, newLen, &buf);
+    if (!buf || len != newLen)
+      return false;
+
+    buf[len - 1] = '.';
+
+    NS_CStringGetData(s, &data);
+    if (strncmp(data, kText, len - 1) != 0 || data[len - 1] != '.')
+      return false;
+
+    NS_CStringContainerFinish(s);
+    return true;
+  }
+
+static bool test_ascii()
+{
+  nsCString testCString;
+  testCString.AppendASCII(kAsciiData);
+  if (!testCString.EqualsLiteral(kAsciiData))
+    return false;
+
+  testCString.AssignASCII(kAsciiData);
+  if (!testCString.LowerCaseEqualsLiteral("hello world"))
+    return false;
+
+  nsString testString;
+  testString.AppendASCII(kAsciiData);
+  if (!testString.EqualsLiteral(kAsciiData))
+    return false;
+
+  testString.AssignASCII(kAsciiData);
+  if (!testString.LowerCaseEqualsLiteral("hello world"))
+    return false;
+
+  return true;
+}
+
+static bool test_chars()
+{
+  nsCString testCString(kAsciiData);
+  if (testCString.First() != 'H')
+    return false;
+  if (testCString.Last() != 'd')
+    return false;
+  testCString.SetCharAt('u', 8);
+  if (!testCString.EqualsASCII("Hello Would"))
+    return false;
+
+  nsString testString(kUnicodeData);
+  if (testString.First() != 'H')
+    return false;
+  if (testString.Last() != 'd')
+    return false;
+  testString.SetCharAt('u', 8);
+  if (!testString.EqualsASCII("Hello Would"))
+    return false;
+
+  return true;
+}
+
+static bool test_stripchars()
+{
+  nsCString test(kAsciiData);
+  test.StripChars("ld");
+  if (!test.EqualsLiteral("Heo Wor"))
+    return false;
+
+  test.Assign(kAsciiData);
+  test.StripWhitespace();
+  if (!test.EqualsLiteral("HelloWorld"))
+    return false;
+
+  return true;
+}
+
+static bool test_trim()
+{
+  static const char kWS[] = "\n\t\r ";
+  static const char kTestString[] = " \n\tTesting...\n\r";
+
+  nsCString test1(kTestString);
+  nsCString test2(kTestString);
+  nsCString test3(kTestString);
+
+  test1.Trim(kWS);
+  test2.Trim(kWS, true, false);
+  test3.Trim(kWS, false, true);
+
+  if (!test1.EqualsLiteral("Testing..."))
+    return false;
+
+  if (!test2.EqualsLiteral("Testing...\n\r"))
+    return false;
+
+  if (!test3.EqualsLiteral(" \n\tTesting..."))
+    return false;
+
+  return true;
+}
+
+static bool test_find()
+{
+  nsString uni(kUnicodeData);
+
+  static const char kHello[] = "Hello";
+  static const char khello[] = "hello";
+  static const char kBye[] = "Bye!";
+
+  int32_t found;
+
+  found = uni.Find(kHello);
+  if (found != 0)
+    return false;
+
+  found = uni.Find(khello, false);
+  if (found != -1)
+    return false;
+ 
+  found = uni.Find(khello, true);
+  if (found != 0)
+    return false;
+
+  found = uni.Find(kBye);
+  if (found != -1)
+    return false;
+
+  found = uni.Find(NS_LITERAL_STRING("World"));
+  if (found != 6)
+    return false;
+
+  found = uni.Find(uni);
+  if (found != 0)
+    return false;
+
+  return true;
+}
+
+static bool test_compressws()
+{
+  nsString check(NS_LITERAL_STRING(" \tTesting  \n\t1\n 2 3\n "));
+  CompressWhitespace(check);
+  return check.EqualsLiteral("Testing 1 2 3");
+}
+
+static bool test_comparisons()
+{
+  bool result;
+
+  // nsString
+
+  NS_NAMED_LITERAL_STRING(shortString1, "Foo");
+  NS_NAMED_LITERAL_STRING(shortString2, "Bar");
+  NS_NAMED_LITERAL_STRING(shortString3, "Bar");
+  NS_NAMED_LITERAL_STRING(shortString4, "bar");
+  NS_NAMED_LITERAL_STRING(longString, "FooBar");
+
+  // ==
+
+  result = (shortString1 == shortString2);
+  if (result)
+    return false;
+
+  result = (shortString2 == shortString3);
+  if (!result)
+    return false;
+
+  result = (shortString3 == shortString4);
+  if (result)
+    return false;
+
+  result = (shortString1 == longString);
+  if (result)
+    return false;
+
+  result = (longString == shortString1);
+  if (result)
+    return false;
+
+  // !=
+
+  result = (shortString1 != shortString2);
+  if (!result)
+    return false;
+
+  result = (shortString2 != shortString3);
+  if (result)
+    return false;
+
+  result = (shortString3 != shortString4);
+  if (!result)
+    return false;
+
+  result = (shortString1 != longString);
+  if (!result)
+    return false;
+
+  result = (longString != shortString1);
+  if (!result)
+    return false;
+
+  // <
+
+  result = (shortString1 < shortString2);
+  if (result)
+    return false;
+
+  result = (shortString2 < shortString1);
+  if (!result)
+    return false;
+
+  result = (shortString1 < longString);
+  if (!result)
+    return false;
+
+  result = (longString < shortString1);
+  if (result)
+    return false;
+
+  result = (shortString2 < shortString3);
+  if (result)
+    return false;
+
+  result = (shortString3 < shortString4);
+  if (!result)
+    return false;
+
+  result = (shortString4 < shortString3);
+  if (result)
+    return false;
+
+  // <=
+
+  result = (shortString1 <= shortString2);
+  if (result)
+    return false;
+
+  result = (shortString2 <= shortString1);
+  if (!result)
+    return false;
+
+  result = (shortString1 <= longString);
+  if (!result)
+    return false;
+
+  result = (longString <= shortString1);
+  if (result)
+    return false;
+
+  result = (shortString2 <= shortString3);
+  if (!result)
+    return false;
+
+  result = (shortString3 <= shortString4);
+  if (!result)
+    return false;
+
+  result = (shortString4 <= shortString3);
+  if (result)
+    return false;
+
+  // >
+
+  result = (shortString1 > shortString2);
+  if (!result)
+    return false;
+
+  result = (shortString2 > shortString1);
+  if (result)
+    return false;
+
+  result = (shortString1 > longString);
+  if (result)
+    return false;
+
+  result = (longString > shortString1);
+  if (!result)
+    return false;
+
+  result = (shortString2 > shortString3);
+  if (result)
+    return false;
+
+  result = (shortString3 > shortString4);
+  if (result)
+    return false;
+
+  result = (shortString4 > shortString3);
+  if (!result)
+    return false;
+
+  // >=
+
+  result = (shortString1 >= shortString2);
+  if (!result)
+    return false;
+
+  result = (shortString2 >= shortString1);
+  if (result)
+    return false;
+
+  result = (shortString1 >= longString);
+  if (result)
+    return false;
+
+  result = (longString >= shortString1);
+  if (!result)
+    return false;
+
+  result = (shortString2 >= shortString3);
+  if (!result)
+    return false;
+
+  result = (shortString3 >= shortString4);
+  if (result)
+    return false;
+
+  result = (shortString4 >= shortString3);
+  if (!result)
+    return false;
+
+  // nsCString
+
+  NS_NAMED_LITERAL_CSTRING(shortCString1, "Foo");
+  NS_NAMED_LITERAL_CSTRING(shortCString2, "Bar");
+  NS_NAMED_LITERAL_CSTRING(shortCString3, "Bar");
+  NS_NAMED_LITERAL_CSTRING(shortCString4, "bar");
+  NS_NAMED_LITERAL_CSTRING(longCString, "FooBar");
+
+  // ==
+
+  result = (shortCString1 == shortCString2);
+  if (result)
+    return false;
+
+  result = (shortCString2 == shortCString3);
+  if (!result)
+    return false;
+
+  result = (shortCString3 == shortCString4);
+  if (result)
+    return false;
+
+  result = (shortCString1 == longCString);
+  if (result)
+    return false;
+
+  result = (longCString == shortCString1);
+  if (result)
+    return false;
+
+  // !=
+
+  result = (shortCString1 != shortCString2);
+  if (!result)
+    return false;
+
+  result = (shortCString2 != shortCString3);
+  if (result)
+    return false;
+
+  result = (shortCString3 != shortCString4);
+  if (!result)
+    return false;
+
+  result = (shortCString1 != longCString);
+  if (!result)
+    return false;
+
+  result = (longCString != shortCString1);
+  if (!result)
+    return false;
+
+  // <
+
+  result = (shortCString1 < shortCString2);
+  if (result)
+    return false;
+
+  result = (shortCString2 < shortCString1);
+  if (!result)
+    return false;
+
+  result = (shortCString1 < longCString);
+  if (!result)
+    return false;
+
+  result = (longCString < shortCString1);
+  if (result)
+    return false;
+
+  result = (shortCString2 < shortCString3);
+  if (result)
+    return false;
+
+  result = (shortCString3 < shortCString4);
+  if (!result)
+    return false;
+
+  result = (shortCString4 < shortCString3);
+  if (result)
+    return false;
+
+  // <=
+
+  result = (shortCString1 <= shortCString2);
+  if (result)
+    return false;
+
+  result = (shortCString2 <= shortCString1);
+  if (!result)
+    return false;
+
+  result = (shortCString1 <= longCString);
+  if (!result)
+    return false;
+
+  result = (longCString <= shortCString1);
+  if (result)
+    return false;
+
+  result = (shortCString2 <= shortCString3);
+  if (!result)
+    return false;
+
+  result = (shortCString3 <= shortCString4);
+  if (!result)
+    return false;
+
+  result = (shortCString4 <= shortCString3);
+  if (result)
+    return false;
+
+  // >
+
+  result = (shortCString1 > shortCString2);
+  if (!result)
+    return false;
+
+  result = (shortCString2 > shortCString1);
+  if (result)
+    return false;
+
+  result = (shortCString1 > longCString);
+  if (result)
+    return false;
+
+  result = (longCString > shortCString1);
+  if (!result)
+    return false;
+
+  result = (shortCString2 > shortCString3);
+  if (result)
+    return false;
+
+  result = (shortCString3 > shortCString4);
+  if (result)
+    return false;
+
+  result = (shortCString4 > shortCString3);
+  if (!result)
+    return false;
+
+  // >=
+
+  result = (shortCString1 >= shortCString2);
+  if (!result)
+    return false;
+
+  result = (shortCString2 >= shortCString1);
+  if (result)
+    return false;
+
+  result = (shortCString1 >= longCString);
+  if (result)
+    return false;
+
+  result = (longCString >= shortCString1);
+  if (!result)
+    return false;
+
+  result = (shortCString2 >= shortCString3);
+  if (!result)
+    return false;
+
+  result = (shortCString3 >= shortCString4);
+  if (result)
+    return false;
+
+  result = (shortCString4 >= shortCString3);
+  if (!result)
+    return false;
+
+  return true;
+}
+
+static bool test_parse_string_helper(const char* str, char separator, int len,
+                                       const char* s1, const char* s2)
+{
+  nsCString data(str);
+  nsTArray<nsCString> results;
+  if (!ParseString(data, separator, results))
+    return false;
+  if (int(results.Length()) != len)
+    return false;
+  const char* strings[] = { s1, s2 };
+  for (int i = 0; i < len; ++i) {
+    if (!results[i].Equals(strings[i]))
+      return false;
+  }
+  return true;
+}
+
+static bool test_parse_string_helper0(const char* str, char separator)
+{
+  return test_parse_string_helper(str, separator, 0, nullptr, nullptr);
+}
+
+static bool test_parse_string_helper1(const char* str, char separator, const char* s1)
+{
+  return test_parse_string_helper(str, separator, 1, s1, nullptr);
+}
+
+static bool test_parse_string_helper2(const char* str, char separator, const char* s1, const char* s2)
+{
+  return test_parse_string_helper(str, separator, 2, s1, s2);
+}
+
+static bool test_parse_string()
+{
+  return test_parse_string_helper1("foo, bar", '_', "foo, bar") &&
+         test_parse_string_helper2("foo, bar", ',', "foo", " bar") &&
+         test_parse_string_helper2("foo, bar ", ' ', "foo,", "bar") &&
+         test_parse_string_helper2("foo,bar", 'o', "f", ",bar") &&
+         test_parse_string_helper0("", '_') &&
+         test_parse_string_helper0("  ", ' ') &&
+         test_parse_string_helper1(" foo", ' ', "foo") &&
+         test_parse_string_helper1("  foo", ' ', "foo");
+}
+
+//----
+
+typedef bool (*TestFunc)();
+
+static const struct Test
+  {
+    const char* name;
+    TestFunc    func;
+  }
+tests[] =
+  {
+    { "test_basic_1", test_basic_1 },
+    { "test_basic_2", test_basic_2 },
+    { "test_convert", test_convert },
+    { "test_append", test_append },
+    { "test_replace", test_replace },
+    { "test_compress_ws", test_compress_ws },
+    { "test_depend", test_depend },
+    { "test_depend_sub", test_depend_sub },
+    { "test_adopt", test_adopt },
+    { "test_adopt_sub", test_adopt_sub },
+    { "test_mutation", test_mutation },
+    { "test_ascii", test_ascii },
+    { "test_chars", test_chars },
+    { "test_stripchars", test_stripchars },
+    { "test_trim", test_trim },
+    { "test_find", test_find },
+    { "test_compressws", test_compressws },
+    { "test_comparisons", test_comparisons },
+    { "test_parse_string", test_parse_string },
+    { nullptr, nullptr }
+  };
+
+//----
+
+int main(int argc, char **argv)
+  {
+    int count = 1;
+    if (argc > 1)
+      count = atoi(argv[1]);
+
+    while (count--)
+      {
+        for (const Test* t = tests; t->name != nullptr; ++t)
+          {
+            printf("%25s : %s\n", t->name, t->func() ? "SUCCESS" : "FAILURE");
+          }
+      }
+    
+    return 0;
+  }
diff --git a/xpcom/tests/external/moz.build b/xpcom/tests/external/moz.build
new file mode 100644
index 000000000..d64560b58
--- /dev/null
+++ b/xpcom/tests/external/moz.build
@@ -0,0 +1,9 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+GeckoSimplePrograms([
+    'TestMinStringAPI',
+])
diff --git a/xpcom/tests/gtest/Helpers.cpp b/xpcom/tests/gtest/Helpers.cpp
new file mode 100644
index 000000000..e06ef901b
--- /dev/null
+++ b/xpcom/tests/gtest/Helpers.cpp
@@ -0,0 +1,133 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Helper routines for xpcom gtests. */
+
+#include "Helpers.h"
+
+#include <algorithm>
+#include "gtest/gtest.h"
+#include "nsIOutputStream.h"
+#include "nsStreamUtils.h"
+#include "nsTArray.h"
+
+namespace testing {
+
+// Populate an array with the given number of bytes.  Data is lorem ipsum
+// random text, but deterministic across multiple calls.
+void
+CreateData(uint32_t aNumBytes, nsTArray<char>& aDataOut)
+{
+  static const char data[] =
+    "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec egestas "
+    "purus eu condimentum iaculis. In accumsan leo eget odio porttitor, non "
+    "rhoncus nulla vestibulum. Etiam lacinia consectetur nisl nec "
+    "sollicitudin. Sed fringilla accumsan diam, pulvinar varius massa. Duis "
+    "mollis dignissim felis, eget tempus nisi tristique ut. Fusce euismod, "
+    "lectus non lacinia tempor, tellus diam suscipit quam, eget hendrerit "
+    "lacus nunc fringilla ante. Sed ultrices massa vitae risus molestie, ut "
+    "finibus quam laoreet nullam.";
+  static const uint32_t dataLength = sizeof(data) - 1;
+
+  aDataOut.SetCapacity(aNumBytes);
+
+  while (aNumBytes > 0) {
+    uint32_t amount = std::min(dataLength, aNumBytes);
+    aDataOut.AppendElements(data, amount);
+    aNumBytes -= amount;
+  }
+}
+
+// Write the given number of bytes out to the stream.  Loop until expected
+// bytes count is reached or an error occurs.
+void
+Write(nsIOutputStream* aStream, const nsTArray<char>& aData, uint32_t aOffset,
+      uint32_t aNumBytes)
+{
+  uint32_t remaining =
+    std::min(aNumBytes, static_cast<uint32_t>(aData.Length() - aOffset));
+
+  while (remaining > 0) {
+    uint32_t numWritten;
+    nsresult rv = aStream->Write(aData.Elements() + aOffset, remaining,
+                                 &numWritten);
+    ASSERT_TRUE(NS_SUCCEEDED(rv));
+    if (numWritten < 1) {
+      break;
+    }
+    aOffset += numWritten;
+    remaining -= numWritten;
+  }
+}
+
+// Write the given number of bytes and then close the stream.
+void
+WriteAllAndClose(nsIOutputStream* aStream, const nsTArray<char>& aData)
+{
+  Write(aStream, aData, 0, aData.Length());
+  aStream->Close();
+}
+
+// Synchronously consume the given input stream and validate the resulting data
+// against the given array of expected values.
+void
+ConsumeAndValidateStream(nsIInputStream* aStream,
+                         const nsTArray<char>& aExpectedData)
+{
+  nsDependentCSubstring data(aExpectedData.Elements(), aExpectedData.Length());
+  ConsumeAndValidateStream(aStream, data);
+}
+
+// Synchronously consume the given input stream and validate the resulting data
+// against the given string of expected values.
+void
+ConsumeAndValidateStream(nsIInputStream* aStream,
+                         const nsACString& aExpectedData)
+{
+  nsAutoCString outputData;
+  nsresult rv = NS_ConsumeStream(aStream, UINT32_MAX, outputData);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+  ASSERT_EQ(aExpectedData.Length(), outputData.Length());
+  ASSERT_TRUE(aExpectedData.Equals(outputData));
+}
+
+NS_IMPL_ISUPPORTS(OutputStreamCallback, nsIOutputStreamCallback);
+
+OutputStreamCallback::OutputStreamCallback()
+  : mCalled(false)
+{
+}
+
+OutputStreamCallback::~OutputStreamCallback()
+{
+}
+
+NS_IMETHODIMP
+OutputStreamCallback::OnOutputStreamReady(nsIAsyncOutputStream* aStream)
+{
+  mCalled = true;
+  return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS(InputStreamCallback, nsIInputStreamCallback);
+
+InputStreamCallback::InputStreamCallback()
+  : mCalled(false)
+{
+}
+
+InputStreamCallback::~InputStreamCallback()
+{
+}
+
+NS_IMETHODIMP
+InputStreamCallback::OnInputStreamReady(nsIAsyncInputStream* aStream)
+{
+  mCalled = true;
+  return NS_OK;
+}
+
+} // namespace testing
diff --git a/xpcom/tests/gtest/Helpers.h b/xpcom/tests/gtest/Helpers.h
new file mode 100644
index 000000000..9cee1b825
--- /dev/null
+++ b/xpcom/tests/gtest/Helpers.h
@@ -0,0 +1,73 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __Helpers_h
+#define __Helpers_h
+
+#include "nsIAsyncInputStream.h"
+#include "nsIAsyncOutputStream.h"
+#include "nsString.h"
+#include "nsTArrayForwardDeclare.h"
+#include <stdint.h>
+
+class nsIInputStream;
+class nsIOutputStream;
+
+namespace testing {
+
+void
+CreateData(uint32_t aNumBytes, nsTArray<char>& aDataOut);
+
+void
+Write(nsIOutputStream* aStream, const nsTArray<char>& aData, uint32_t aOffset,
+      uint32_t aNumBytes);
+
+void
+WriteAllAndClose(nsIOutputStream* aStream, const nsTArray<char>& aData);
+
+void
+ConsumeAndValidateStream(nsIInputStream* aStream,
+                         const nsTArray<char>& aExpectedData);
+
+void
+ConsumeAndValidateStream(nsIInputStream* aStream,
+                         const nsACString& aExpectedData);
+
+class OutputStreamCallback final : public nsIOutputStreamCallback
+{
+public:
+  OutputStreamCallback();
+
+  bool Called() const { return mCalled; }
+
+private:
+  ~OutputStreamCallback();
+
+  bool mCalled;
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIOUTPUTSTREAMCALLBACK
+};
+
+class InputStreamCallback final : public nsIInputStreamCallback
+{
+public:
+  InputStreamCallback();
+
+  bool Called() const { return mCalled; }
+
+private:
+  ~InputStreamCallback();
+
+  bool mCalled;
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIINPUTSTREAMCALLBACK
+};
+
+} // namespace testing
+
+#endif // __Helpers_h
diff --git a/xpcom/tests/gtest/TestAllocReplacement.cpp b/xpcom/tests/gtest/TestAllocReplacement.cpp
new file mode 100644
index 000000000..7bcf3d4ad
--- /dev/null
+++ b/xpcom/tests/gtest/TestAllocReplacement.cpp
@@ -0,0 +1,175 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Attributes.h"
+#include "mozilla/Function.h"
+#include "mozilla/mozalloc.h"
+#include "mozilla/ScopeExit.h"
+#include "nsCOMPtr.h"
+#include "nsIMemoryReporter.h"
+#include "nsServiceManagerUtils.h"
+#include "gtest/gtest.h"
+
+// We want to ensure that various functions are hooked properly and that
+// allocations are getting routed through jemalloc.  The strategy
+// pursued below relies on jemalloc's statistics tracking: we measure
+// the size of the jemalloc heap using nsIMemoryReporterManager,
+// allocate a chunk of memory with whatever function is supposed to be
+// hooked, and then ask for the size of the jemalloc heap again.  If the
+// function has been hooked correctly, then the heap size should be
+// different between the two measurements.  We can also check the
+// hooking of |free| and similar functions: once we free() the returned
+// pointer, we can measure the jemalloc heap size again, expecting it to
+// be identical to the size prior to the allocation.
+//
+// If we're not using jemalloc, then nsIMemoryReporterManager will
+// simply report an error, and we will ignore the entire test.
+//
+// This strategy is not perfect: it relies on GTests being
+// single-threaded, which they are, and no other threads doing
+// allocation during the test, which is uncertain, as XPCOM has started
+// up during gtests, and who knows what might be going on behind the
+// scenes.  This latter assumption, however, does not seem to be a
+// problem in practice.
+#if defined(MOZ_MEMORY)
+#define ALLOCATION_ASSERT(b) ASSERT_TRUE((b))
+#else
+#define ALLOCATION_ASSERT(b) (void)(b)
+#endif
+
+#define ASSERT_ALLOCATION_HAPPENED(lambda)      \
+  ALLOCATION_ASSERT(ValidateHookedAllocation(lambda, free));
+
+// We do run the risk of OOM'ing when we allocate something...all we can
+// do is try to allocate something so small that OOM'ing is unlikely.
+const size_t kAllocAmount = 16;
+
+// We declare this function MOZ_NEVER_INLINE to work around optimizing
+// compilers.  If we permitted inlining here, then the compiler might
+// inline both this function and the calls to the function pointers we
+// pass in, giving something like:
+//
+//   void* p = malloc(...);
+//   ...do nothing with p except check nullptr-ness...
+//   free(p);
+//
+// and the optimizer can delete the calls to malloc and free entirely,
+// which would make checking that the jemalloc heap had never changed
+// difficult.
+static MOZ_NEVER_INLINE bool
+ValidateHookedAllocation(void* (*aAllocator)(void),
+                         void (*aFreeFunction)(void*))
+{
+  nsCOMPtr<nsIMemoryReporterManager> manager =
+    do_GetService("@mozilla.org/memory-reporter-manager;1");
+
+  int64_t before = 0;
+  nsresult rv = manager->GetHeapAllocated(&before);
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+
+  {
+    void* p = aAllocator();
+
+    if (!p) {
+      return false;
+    }
+
+    int64_t after = 0;
+    rv = manager->GetHeapAllocated(&after);
+
+    // Regardless of whether that call succeeded or failed, we are done with
+    // the allocated buffer now.
+    aFreeFunction(p);
+
+    if (NS_FAILED(rv)) {
+      return false;
+    }
+
+    // Verify that our heap stats have changed.
+    if ((before + int64_t(kAllocAmount)) != after) {
+      return false;
+    }
+  }
+
+  // Verify that freeing the allocated pointer resets our heap to what it
+  // was before.
+  int64_t after = 0;
+  rv = manager->GetHeapAllocated(&after);
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+
+  return before == after;
+}
+
+TEST(AllocReplacement, malloc_check)
+{
+  ASSERT_ALLOCATION_HAPPENED([] {
+    return malloc(kAllocAmount);
+  });
+}
+
+TEST(AllocReplacement, calloc_check)
+{
+  ASSERT_ALLOCATION_HAPPENED([] {
+    return calloc(1, kAllocAmount);
+  });
+}
+
+TEST(AllocReplacement, realloc_check)
+{
+  ASSERT_ALLOCATION_HAPPENED([] {
+    return realloc(nullptr, kAllocAmount);
+  });
+}
+
+#if defined(HAVE_POSIX_MEMALIGN)
+TEST(AllocReplacement, posix_memalign_check)
+{
+  ASSERT_ALLOCATION_HAPPENED([] {
+    void* p = nullptr;
+    int result = posix_memalign(&p, sizeof(void*), kAllocAmount);
+    if (result != 0) {
+      return static_cast<void*>(nullptr);
+    }
+    return p;
+  });
+}
+#endif
+
+#if defined(XP_WIN)
+#include <windows.h>
+
+#undef ASSERT_ALLOCATION_HAPPENED
+#define ASSERT_ALLOCATION_HAPPENED(lambda)      \
+  ALLOCATION_ASSERT(ValidateHookedAllocation(lambda, [](void* p) { \
+    HeapFree(GetProcessHeap(), 0, p); \
+  }));
+
+TEST(AllocReplacement, HeapAlloc_check)
+{
+  ASSERT_ALLOCATION_HAPPENED([] {
+    HANDLE h = GetProcessHeap();
+    return HeapAlloc(h, 0, kAllocAmount);
+  });
+}
+
+TEST(AllocReplacement, HeapReAlloc_check)
+{
+  ASSERT_ALLOCATION_HAPPENED([] {
+    HANDLE h = GetProcessHeap();
+    void *p = HeapAlloc(h, 0, kAllocAmount / 2);
+
+    if (!p) {
+      return static_cast<void*>(nullptr);
+    }
+
+    return HeapReAlloc(h, 0, p, kAllocAmount);
+  });
+}
+#endif
diff --git a/xpcom/tests/gtest/TestAtoms.cpp b/xpcom/tests/gtest/TestAtoms.cpp
new file mode 100644
index 000000000..da3cc5ea2
--- /dev/null
+++ b/xpcom/tests/gtest/TestAtoms.cpp
@@ -0,0 +1,153 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ArrayUtils.h"
+
+#include "nsIAtom.h"
+#include "nsString.h"
+#include "UTFStrings.h"
+#include "nsIServiceManager.h"
+#include "nsStaticAtom.h"
+
+#include "gtest/gtest.h"
+
+using namespace mozilla;
+
+namespace TestAtoms {
+
+TEST(Atoms, Basic)
+{
+  for (unsigned int i = 0; i < ArrayLength(ValidStrings); ++i) {
+    nsDependentString str16(ValidStrings[i].m16);
+    nsDependentCString str8(ValidStrings[i].m8);
+
+    nsCOMPtr<nsIAtom> atom = NS_Atomize(str16);
+
+    EXPECT_TRUE(atom->Equals(str16));
+
+    nsString tmp16;
+    nsCString tmp8;
+    atom->ToString(tmp16);
+    atom->ToUTF8String(tmp8);
+    EXPECT_TRUE(str16.Equals(tmp16));
+    EXPECT_TRUE(str8.Equals(tmp8));
+
+    EXPECT_TRUE(nsDependentString(atom->GetUTF16String()).Equals(str16));
+
+    EXPECT_TRUE(nsAtomString(atom).Equals(str16));
+    EXPECT_TRUE(nsDependentAtomString(atom).Equals(str16));
+    EXPECT_TRUE(nsAtomCString(atom).Equals(str8));
+  }
+}
+
+TEST(Atoms, 16vs8)
+{
+  for (unsigned int i = 0; i < ArrayLength(ValidStrings); ++i) {
+    nsCOMPtr<nsIAtom> atom16 = NS_Atomize(ValidStrings[i].m16);
+    nsCOMPtr<nsIAtom> atom8 = NS_Atomize(ValidStrings[i].m8);
+    EXPECT_EQ(atom16, atom8);
+  }
+}
+
+TEST(Atoms, BufferSharing)
+{
+  nsString unique;
+  unique.AssignLiteral("this is a unique string !@#$");
+
+  nsCOMPtr<nsIAtom> atom = NS_Atomize(unique);
+
+  EXPECT_EQ(unique.get(), atom->GetUTF16String());
+}
+
+TEST(Atoms, Null)
+{
+  nsAutoString str(NS_LITERAL_STRING("string with a \0 char"));
+  nsDependentString strCut(str.get());
+
+  EXPECT_FALSE(str.Equals(strCut));
+
+  nsCOMPtr<nsIAtom> atomCut = NS_Atomize(strCut);
+  nsCOMPtr<nsIAtom> atom = NS_Atomize(str);
+
+  EXPECT_EQ(atom->GetLength(), str.Length());
+  EXPECT_TRUE(atom->Equals(str));
+  EXPECT_NE(atom, atomCut);
+  EXPECT_TRUE(atomCut->Equals(strCut));
+}
+
+TEST(Atoms, Invalid)
+{
+  for (unsigned int i = 0; i < ArrayLength(Invalid16Strings); ++i) {
+    nsrefcnt count = NS_GetNumberOfAtoms();
+
+    {
+      nsCOMPtr<nsIAtom> atom16 = NS_Atomize(Invalid16Strings[i].m16);
+      EXPECT_TRUE(atom16->Equals(nsDependentString(Invalid16Strings[i].m16)));
+    }
+
+    EXPECT_EQ(count, NS_GetNumberOfAtoms());
+  }
+
+  for (unsigned int i = 0; i < ArrayLength(Invalid8Strings); ++i) {
+    nsrefcnt count = NS_GetNumberOfAtoms();
+
+    {
+      nsCOMPtr<nsIAtom> atom8 = NS_Atomize(Invalid8Strings[i].m8);
+      nsCOMPtr<nsIAtom> atom16 = NS_Atomize(Invalid8Strings[i].m16);
+      EXPECT_EQ(atom16, atom8);
+      EXPECT_TRUE(atom16->Equals(nsDependentString(Invalid8Strings[i].m16)));
+    }
+
+    EXPECT_EQ(count, NS_GetNumberOfAtoms());
+  }
+
+// Don't run this test in debug builds as that intentionally asserts.
+#ifndef DEBUG
+  nsCOMPtr<nsIAtom> emptyAtom = NS_Atomize("");
+
+  for (unsigned int i = 0; i < ArrayLength(Malformed8Strings); ++i) {
+    nsrefcnt count = NS_GetNumberOfAtoms();
+
+    nsCOMPtr<nsIAtom> atom8 = NS_Atomize(Malformed8Strings[i]);
+    EXPECT_EQ(atom8, emptyAtom);
+    EXPECT_EQ(count, NS_GetNumberOfAtoms());
+  }
+#endif
+}
+
+#define FIRST_ATOM_STR "first static atom. Hello!"
+#define SECOND_ATOM_STR "second static atom. @World!"
+#define THIRD_ATOM_STR "third static atom?!"
+
+bool
+isStaticAtom(nsIAtom* atom)
+{
+  // Don't use logic && in order to ensure that all addrefs/releases are always
+  // run, even if one of the tests fail. This allows us to run this code on a
+  // non-static atom without affecting its refcount.
+  bool rv = (atom->AddRef() == 2);
+  rv &= (atom->AddRef() == 2);
+  rv &= (atom->AddRef() == 2);
+
+  rv &= (atom->Release() == 1);
+  rv &= (atom->Release() == 1);
+  rv &= (atom->Release() == 1);
+  return rv;
+}
+
+TEST(Atoms, Table)
+{
+  nsrefcnt count = NS_GetNumberOfAtoms();
+
+  nsCOMPtr<nsIAtom> thirdDynamic = NS_Atomize(THIRD_ATOM_STR);
+
+  EXPECT_FALSE(isStaticAtom(thirdDynamic));
+
+  EXPECT_TRUE(thirdDynamic);
+  EXPECT_EQ(NS_GetNumberOfAtoms(), count + 1);
+}
+
+}
diff --git a/xpcom/tests/gtest/TestAutoPtr.cpp b/xpcom/tests/gtest/TestAutoPtr.cpp
new file mode 100644
index 000000000..362ba55c5
--- /dev/null
+++ b/xpcom/tests/gtest/TestAutoPtr.cpp
@@ -0,0 +1,220 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+// vim:cindent:ts=4:et:sw=4:
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsAutoPtr.h"
+#include "gtest/gtest.h"
+
+class TestObjectBaseA {
+  public:
+    // Virtual dtor for deleting through base class pointer
+    virtual ~TestObjectBaseA() { }
+    void MemberFunction(int, int*, int&)
+    {
+    }
+    virtual void VirtualMemberFunction(int, int*, int&) { };
+    virtual void VirtualConstMemberFunction(int, int*, int&) const { };
+    int fooA;
+};
+
+class TestObjectBaseB {
+  public:
+    // Virtual dtor for deleting through base class pointer
+    virtual ~TestObjectBaseB() { }
+    int fooB;
+};
+
+class TestObject : public TestObjectBaseA, public TestObjectBaseB {
+  public:
+    TestObject()
+    {
+    }
+
+    // Virtual dtor for deleting through base class pointer
+    virtual ~TestObject()
+    {
+      destructed++;
+    }
+
+    virtual void VirtualMemberFunction(int, int*, int&) override
+    {
+    }
+    virtual void VirtualConstMemberFunction(int, int*, int&) const override
+    {
+    }
+
+    static int destructed;
+    static const void* last_ptr;
+};
+
+int TestObject::destructed = 0;
+const void* TestObject::last_ptr = nullptr;
+
+static void CreateTestObject(TestObject **aResult)
+{
+  *aResult = new TestObject();
+}
+
+static void DoSomethingWithTestObject(TestObject *aIn)
+{
+  TestObject::last_ptr = static_cast<void*>(aIn);
+}
+
+static void DoSomethingWithConstTestObject(const TestObject *aIn)
+{
+  TestObject::last_ptr = static_cast<const void*>(aIn);
+}
+
+static void DoSomethingWithTestObjectBaseB(TestObjectBaseB *aIn)
+{
+  TestObject::last_ptr = static_cast<void*>(aIn);
+}
+
+static void DoSomethingWithConstTestObjectBaseB(const TestObjectBaseB *aIn)
+{
+  TestObject::last_ptr = static_cast<const void*>(aIn);
+}
+
+TEST(AutoPtr, Assignment)
+{
+  TestObject::destructed = 0;
+
+  {
+    nsAutoPtr<TestObject> pobj( new TestObject() );
+  }
+
+  ASSERT_EQ(1, TestObject::destructed);
+
+  {
+    nsAutoPtr<TestObject> pobj( new TestObject() );
+    pobj = new TestObject();
+    ASSERT_EQ(2, TestObject::destructed);
+  }
+
+  ASSERT_EQ(3, TestObject::destructed);
+}
+
+TEST(AutoPtr, getter_Transfers)
+{
+  TestObject::destructed = 0;
+
+  {
+    nsAutoPtr<TestObject> ptr;
+    CreateTestObject(getter_Transfers(ptr));
+  }
+
+  ASSERT_EQ(1, TestObject::destructed);
+}
+
+TEST(AutoPtr, Casting)
+{
+  // This comparison is always false, as it should be. The extra parens
+  // suppress a -Wunreachable-code warning about printf being unreachable.
+  ASSERT_NE(((void*)(TestObject*)0x1000),
+             ((void*)(TestObjectBaseB*)(TestObject*)0x1000));
+
+  {
+    nsAutoPtr<TestObject> p1(new TestObject());
+    TestObjectBaseB *p2 = p1;
+    ASSERT_NE(static_cast<void*>(p1),
+               static_cast<void*>(p2));
+    ASSERT_EQ(p1, p2);
+    ASSERT_FALSE(p1 != p2);
+    ASSERT_EQ(p2, p1);
+    ASSERT_FALSE(p2 != p1);
+  }
+
+  {
+    TestObject *p1 = new TestObject();
+    nsAutoPtr<TestObjectBaseB> p2(p1);
+    ASSERT_EQ(p1, p2);
+    ASSERT_FALSE(p1 != p2);
+    ASSERT_EQ(p2, p1);
+    ASSERT_FALSE(p2 != p1);
+  }
+}
+
+TEST(AutoPtr, Forget)
+{
+  TestObject::destructed = 0;
+
+  {
+    nsAutoPtr<TestObject> pobj( new TestObject() );
+    nsAutoPtr<TestObject> pobj2( pobj.forget() );
+    ASSERT_EQ(0, TestObject::destructed);
+  }
+
+  ASSERT_EQ(1, TestObject::destructed);
+}
+
+TEST(AutoPtr, Construction)
+{
+  TestObject::destructed = 0;
+
+  {
+    nsAutoPtr<TestObject> pobj(new TestObject());
+  }
+
+  ASSERT_EQ(1, TestObject::destructed);
+}
+
+TEST(AutoPtr, ImplicitConversion)
+{
+  // This test is basically successful if it builds. We add a few assertions
+  // to make gtest happy.
+  TestObject::destructed = 0;
+
+  {
+    nsAutoPtr<TestObject> pobj(new TestObject());
+    DoSomethingWithTestObject(pobj);
+    DoSomethingWithConstTestObject(pobj);
+  }
+
+  ASSERT_EQ(1, TestObject::destructed);
+
+  {
+    nsAutoPtr<TestObject> pobj(new TestObject());
+    DoSomethingWithTestObjectBaseB(pobj);
+    DoSomethingWithConstTestObjectBaseB(pobj);
+  }
+
+  ASSERT_EQ(2, TestObject::destructed);
+
+  {
+    const nsAutoPtr<TestObject> pobj(new TestObject());
+    DoSomethingWithTestObject(pobj);
+    DoSomethingWithConstTestObject(pobj);
+  }
+
+  ASSERT_EQ(3, TestObject::destructed);
+
+  {
+    const nsAutoPtr<TestObject> pobj(new TestObject());
+    DoSomethingWithTestObjectBaseB(pobj);
+    DoSomethingWithConstTestObjectBaseB(pobj);
+  }
+
+  ASSERT_EQ(4, TestObject::destructed);
+}
+
+TEST(AutoPtr, ArrowOperator)
+{
+  // This test is basically successful if it builds. We add a few assertions
+  // to make gtest happy.
+  TestObject::destructed = 0;
+
+  {
+    int test = 1;
+    void (TestObjectBaseA::*fPtr)( int, int*, int& ) = &TestObjectBaseA::MemberFunction;
+    void (TestObjectBaseA::*fVPtr)( int, int*, int& ) = &TestObjectBaseA::VirtualMemberFunction;
+    void (TestObjectBaseA::*fVCPtr)( int, int*, int& ) const = &TestObjectBaseA::VirtualConstMemberFunction;
+    nsAutoPtr<TestObjectBaseA> pobj(new TestObject());
+    (pobj->*fPtr)(test, &test, test);
+    (pobj->*fVPtr)(test, &test, test);
+    (pobj->*fVCPtr)(test, &test, test);
+  }
+
+  ASSERT_EQ(1, TestObject::destructed);
+}
diff --git a/xpcom/tests/gtest/TestAutoRef.cpp b/xpcom/tests/gtest/TestAutoRef.cpp
new file mode 100644
index 000000000..49042e8fb
--- /dev/null
+++ b/xpcom/tests/gtest/TestAutoRef.cpp
@@ -0,0 +1,56 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+// vim:cindent:ts=4:et:sw=4:
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsAutoRef.h"
+#include "gtest/gtest.h"
+
+struct TestObjectA {
+public:
+  TestObjectA() : mRefCnt(0) {
+  }
+
+  ~TestObjectA() {
+    EXPECT_EQ(mRefCnt, 0);
+  }
+
+public:
+  int mRefCnt;
+};
+
+template <>
+class nsAutoRefTraits<TestObjectA> : public nsPointerRefTraits<TestObjectA>
+{
+public:
+  static int mTotalRefsCnt;
+
+  static void Release(TestObjectA *ptr) {
+    ptr->mRefCnt--;
+    if (ptr->mRefCnt == 0) {
+      delete ptr;
+    }
+  }
+
+  static void AddRef(TestObjectA *ptr) {
+    ptr->mRefCnt++;
+  }
+};
+
+int nsAutoRefTraits<TestObjectA>::mTotalRefsCnt = 0;
+
+TEST(AutoRef, Assignment)
+{
+  {
+    nsCountedRef<TestObjectA> a(new TestObjectA());
+    ASSERT_EQ(a->mRefCnt, 1);
+
+    nsCountedRef<TestObjectA> b;
+    ASSERT_EQ(b.get(), nullptr);
+
+    a.swap(b);
+    ASSERT_EQ(b->mRefCnt, 1);
+    ASSERT_EQ(a.get(), nullptr);
+  }
+}
diff --git a/xpcom/tests/gtest/TestBase64.cpp b/xpcom/tests/gtest/TestBase64.cpp
new file mode 100644
index 000000000..d8105619b
--- /dev/null
+++ b/xpcom/tests/gtest/TestBase64.cpp
@@ -0,0 +1,291 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Attributes.h"
+#include "nsIScriptableBase64Encoder.h"
+#include "nsIInputStream.h"
+#include "nsString.h"
+
+#include "gtest/gtest.h"
+
+struct Chunk {
+  Chunk(uint32_t l, const char* c)
+    : mLength(l), mData(c)
+  {}
+
+  uint32_t mLength;
+  const char* mData;
+};
+
+struct Test {
+  Test(Chunk* c, const char* r)
+    : mChunks(c), mResult(r)
+  {}
+
+  Chunk* mChunks;
+  const char* mResult;
+};
+
+static Chunk kTest1Chunks[] =
+{
+   Chunk(9, "Hello sir"),
+   Chunk(0, nullptr)
+};
+
+static Chunk kTest2Chunks[] =
+{
+   Chunk(3, "Hel"),
+   Chunk(3, "lo "),
+   Chunk(3, "sir"),
+   Chunk(0, nullptr)
+};
+
+static Chunk kTest3Chunks[] =
+{
+   Chunk(1, "I"),
+   Chunk(0, nullptr)
+};
+
+static Chunk kTest4Chunks[] =
+{
+   Chunk(2, "Hi"),
+   Chunk(0, nullptr)
+};
+
+static Chunk kTest5Chunks[] =
+{
+   Chunk(1, "B"),
+   Chunk(2, "ob"),
+   Chunk(0, nullptr)
+};
+
+static Chunk kTest6Chunks[] =
+{
+   Chunk(2, "Bo"),
+   Chunk(1, "b"),
+   Chunk(0, nullptr)
+};
+
+static Chunk kTest7Chunks[] =
+{
+   Chunk(1, "F"),    // Carry over 1
+   Chunk(4, "iref"), // Carry over 2
+   Chunk(2, "ox"),   //            1
+   Chunk(4, " is "), //            2
+   Chunk(2, "aw"),   //            1
+   Chunk(4, "esom"), //            2
+   Chunk(2, "e!"),
+   Chunk(0, nullptr)
+};
+
+static Chunk kTest8Chunks[] =
+{
+   Chunk(5, "ALL T"),
+   Chunk(1, "H"),
+   Chunk(4, "ESE "),
+   Chunk(2, "WO"),
+   Chunk(21, "RLDS ARE YOURS EXCEPT"),
+   Chunk(9, " EUROPA. "),
+   Chunk(25, "ATTEMPT NO LANDING THERE."),
+   Chunk(0, nullptr)
+};
+
+static Test kTests[] =
+  {
+    // Test 1, test a simple round string in one chunk
+    Test(
+      kTest1Chunks,
+      "SGVsbG8gc2ly"
+    ),
+    // Test 2, test a simple round string split into round chunks
+    Test(
+      kTest2Chunks,
+      "SGVsbG8gc2ly"
+    ),
+    // Test 3, test a single chunk that's 2 short
+    Test(
+      kTest3Chunks,
+      "SQ=="
+    ),
+    // Test 4, test a single chunk that's 1 short
+    Test(
+      kTest4Chunks,
+      "SGk="
+    ),
+    // Test 5, test a single chunk that's 2 short, followed by a chunk of 2
+    Test(
+      kTest5Chunks,
+      "Qm9i"
+    ),
+    // Test 6, test a single chunk that's 1 short, followed by a chunk of 1
+    Test(
+      kTest6Chunks,
+      "Qm9i"
+    ),
+    // Test 7, test alternating carryovers
+    Test(
+      kTest7Chunks,
+      "RmlyZWZveCBpcyBhd2Vzb21lIQ=="
+    ),
+    // Test 8, test a longish string
+    Test(
+      kTest8Chunks,
+      "QUxMIFRIRVNFIFdPUkxEUyBBUkUgWU9VUlMgRVhDRVBUIEVVUk9QQS4gQVRURU1QVCBOTyBMQU5ESU5HIFRIRVJFLg=="
+    ),
+    // Terminator
+    Test(
+      nullptr,
+      nullptr
+    )
+  };
+
+class FakeInputStream final : public nsIInputStream
+{
+  ~FakeInputStream() {}
+
+public:
+
+  FakeInputStream()
+  : mTestNumber(0),
+    mTest(&kTests[0]),
+    mChunk(&mTest->mChunks[0]),
+    mClosed(false)
+  {}
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIINPUTSTREAM
+
+  void Reset();
+  bool NextTest();
+  void CheckTest(nsACString& aResult);
+  void CheckTest(nsAString& aResult);
+private:
+  uint32_t mTestNumber;
+  const Test* mTest;
+  const Chunk* mChunk;
+  bool mClosed;
+};
+
+NS_IMPL_ISUPPORTS(FakeInputStream, nsIInputStream)
+
+NS_IMETHODIMP
+FakeInputStream::Close()
+{
+  mClosed = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+FakeInputStream::Available(uint64_t* aAvailable)
+{
+  *aAvailable = 0;
+
+  if (mClosed)
+    return NS_BASE_STREAM_CLOSED;
+
+  const Chunk* chunk = mChunk;
+  while (chunk->mLength) {
+    *aAvailable += chunk->mLength;
+    chunk++;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+FakeInputStream::Read(char* aBuffer, uint32_t aCount, uint32_t* aOut)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+FakeInputStream::ReadSegments(nsWriteSegmentFun aWriter,
+                              void* aClosure,
+                              uint32_t aCount,
+                              uint32_t* aRead)
+{
+  *aRead = 0;
+
+  if (mClosed)
+    return NS_BASE_STREAM_CLOSED;
+
+  while (mChunk->mLength) {
+    uint32_t written = 0;
+
+    nsresult rv = (*aWriter)(this, aClosure, mChunk->mData,
+                             *aRead, mChunk->mLength, &written);
+
+    *aRead += written;
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    mChunk++;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+FakeInputStream::IsNonBlocking(bool* aIsBlocking)
+{
+  *aIsBlocking = false;
+  return NS_OK;
+}
+
+void
+FakeInputStream::Reset()
+{
+  mClosed = false;
+  mChunk = &mTest->mChunks[0];
+}
+
+bool
+FakeInputStream::NextTest()
+{
+  mTestNumber++;
+  mTest = &kTests[mTestNumber];
+  mChunk = &mTest->mChunks[0];
+  mClosed = false;
+
+  return mTest->mChunks ? true : false;
+}
+
+void
+FakeInputStream::CheckTest(nsACString& aResult)
+{
+  ASSERT_STREQ(aResult.BeginReading(), mTest->mResult);
+}
+
+void
+FakeInputStream::CheckTest(nsAString& aResult)
+{
+  ASSERT_TRUE(aResult.EqualsASCII(mTest->mResult)) <<
+    "Actual:   " << aResult.BeginReading() << std::endl <<
+    "Expected: " << mTest->mResult;
+}
+
+TEST(Base64, Test)
+{
+  nsCOMPtr<nsIScriptableBase64Encoder> encoder =
+    do_CreateInstance("@mozilla.org/scriptablebase64encoder;1");
+  ASSERT_TRUE(encoder);
+
+  RefPtr<FakeInputStream> stream = new FakeInputStream();
+  do {
+    nsString wideString;
+    nsCString string;
+
+    nsresult rv;
+    rv = encoder->EncodeToString(stream, 0, wideString);
+    ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+    stream->Reset();
+
+    rv = encoder->EncodeToCString(stream, 0, string);
+    ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+    stream->CheckTest(wideString);
+    stream->CheckTest(string);
+  } while (stream->NextTest());
+}
diff --git a/xpcom/tests/gtest/TestCOMArray.cpp b/xpcom/tests/gtest/TestCOMArray.cpp
new file mode 100644
index 000000000..6703bf9d1
--- /dev/null
+++ b/xpcom/tests/gtest/TestCOMArray.cpp
@@ -0,0 +1,286 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+// vim:cindent:ts=4:et:sw=4:
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCOMArray.h"
+#include "gtest/gtest.h"
+
+// {9e70a320-be02-11d1-8031-006008159b5a}
+#define NS_IFOO_IID \
+  {0x9e70a320, 0xbe02, 0x11d1,    \
+    {0x80, 0x31, 0x00, 0x60, 0x08, 0x15, 0x9b, 0x5a}}
+
+class IFoo : public nsISupports {
+public:
+
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_IFOO_IID)
+
+  NS_IMETHOD_(MozExternalRefCountType) RefCnt() = 0;
+  NS_IMETHOD_(int32_t) ID() = 0;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(IFoo, NS_IFOO_IID)
+
+class Foo final : public IFoo {
+  ~Foo();
+
+public:
+
+  explicit Foo(int32_t aID);
+
+  // nsISupports implementation
+  NS_DECL_ISUPPORTS
+
+  // IFoo implementation
+  NS_IMETHOD_(MozExternalRefCountType) RefCnt() override { return mRefCnt; }
+  NS_IMETHOD_(int32_t) ID() override { return mID; }
+
+  static int32_t gCount;
+
+  int32_t mID;
+};
+
+int32_t Foo::gCount = 0;
+
+Foo::Foo(int32_t aID)
+{
+  mID = aID;
+  ++gCount;
+}
+
+Foo::~Foo()
+{
+  --gCount;
+}
+
+NS_IMPL_ISUPPORTS(Foo, IFoo)
+
+
+// {0e70a320-be02-11d1-8031-006008159b5a}
+#define NS_IBAR_IID \
+  {0x0e70a320, 0xbe02, 0x11d1,    \
+    {0x80, 0x31, 0x00, 0x60, 0x08, 0x15, 0x9b, 0x5a}}
+
+class IBar : public nsISupports {
+public:
+
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_IBAR_IID)
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(IBar, NS_IBAR_IID)
+
+class Bar final : public IBar {
+public:
+
+  explicit Bar(nsCOMArray<IBar>& aArray);
+
+  // nsISupports implementation
+  NS_DECL_ISUPPORTS
+
+  static int32_t sReleaseCalled;
+
+private:
+  ~Bar();
+
+  nsCOMArray<IBar>& mArray;
+};
+
+int32_t Bar::sReleaseCalled = 0;
+
+typedef nsCOMArray<IBar> Array2;
+
+Bar::Bar(Array2& aArray)
+  : mArray(aArray)
+{
+}
+
+Bar::~Bar()
+{
+  EXPECT_FALSE(mArray.RemoveObject(this));
+}
+
+NS_IMPL_ADDREF(Bar)
+NS_IMPL_QUERY_INTERFACE(Bar, IBar)
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+Bar::Release(void)
+{
+  ++Bar::sReleaseCalled;
+  EXPECT_GT(int(mRefCnt), 0);
+  NS_ASSERT_OWNINGTHREAD(_class);
+  --mRefCnt;
+  NS_LOG_RELEASE(this, mRefCnt, "Bar");
+  if (mRefCnt == 0) {
+    mRefCnt = 1; /* stabilize */
+    delete this;
+    return 0;
+  }
+  return mRefCnt;
+}
+
+TEST(COMArray, Sizing)
+{
+  nsCOMArray<IFoo> arr;
+
+  for (int32_t i = 0; i < 20; ++i) {
+    nsCOMPtr<IFoo> foo = new Foo(i);
+    arr.AppendObject(foo);
+  }
+
+  ASSERT_EQ(arr.Count(), int32_t(20));
+  ASSERT_EQ(Foo::gCount, int32_t(20));
+
+  arr.TruncateLength(10);
+
+  ASSERT_EQ(arr.Count(), int32_t(10));
+  ASSERT_EQ(Foo::gCount, int32_t(10));
+
+  arr.SetCount(30);
+
+  ASSERT_EQ(arr.Count(), int32_t(30));
+  ASSERT_EQ(Foo::gCount, int32_t(10));
+
+  for (int32_t i = 0; i < 10; ++i) {
+	ASSERT_NE(arr[i], nullptr);
+  }
+
+  for (int32_t i = 10; i < 30; ++i) {
+	ASSERT_EQ(arr[i], nullptr);
+  }
+}
+
+TEST(COMArray, ObjectFunctions)
+{
+  int32_t base;
+  {
+    nsCOMArray<IBar> arr2;
+
+    IBar *thirdObject = nullptr,
+         *fourthObject = nullptr,
+         *fifthObject = nullptr,
+         *ninthObject = nullptr;
+    for (int32_t i = 0; i < 20; ++i) {
+      nsCOMPtr<IBar> bar = new Bar(arr2);
+      switch (i) {
+      case 2:
+        thirdObject = bar; break;
+      case 3:
+        fourthObject = bar; break;
+      case 4:
+        fifthObject = bar; break;
+      case 8:
+        ninthObject = bar; break;
+      }
+      arr2.AppendObject(bar);
+    }
+
+    base = Bar::sReleaseCalled;
+
+    arr2.SetCount(10);
+    ASSERT_EQ(Bar::sReleaseCalled, base + 10);
+    ASSERT_EQ(arr2.Count(), int32_t(10));
+
+    arr2.RemoveObjectAt(9);
+    ASSERT_EQ(Bar::sReleaseCalled, base + 11);
+    ASSERT_EQ(arr2.Count(), int32_t(9));
+
+    arr2.RemoveObject(ninthObject);
+    ASSERT_EQ(Bar::sReleaseCalled, base + 12);
+    ASSERT_EQ(arr2.Count(), int32_t(8));
+
+    arr2.RemoveObjectsAt(2, 3);
+    ASSERT_EQ(Bar::sReleaseCalled, base + 15);
+    ASSERT_EQ(arr2.Count(), int32_t(5));
+    for (int32_t j = 0; j < arr2.Count(); ++j) {
+      ASSERT_NE(arr2.ObjectAt(j), thirdObject);
+      ASSERT_NE(arr2.ObjectAt(j), fourthObject);
+      ASSERT_NE(arr2.ObjectAt(j), fifthObject);
+    }
+
+    arr2.RemoveObjectsAt(4, 1);
+    ASSERT_EQ(Bar::sReleaseCalled, base + 16);
+    ASSERT_EQ(arr2.Count(), int32_t(4));
+
+    arr2.Clear();
+    ASSERT_EQ(Bar::sReleaseCalled, base + 20);
+  }
+}
+
+TEST(COMArray, ElementFunctions)
+{
+  int32_t base;
+  {
+    nsCOMArray<IBar> arr2;
+
+    IBar *thirdElement = nullptr,
+         *fourthElement = nullptr,
+         *fifthElement = nullptr,
+         *ninthElement = nullptr;
+    for (int32_t i = 0; i < 20; ++i) {
+      nsCOMPtr<IBar> bar = new Bar(arr2);
+      switch (i) {
+      case 2:
+        thirdElement = bar; break;
+      case 3:
+        fourthElement = bar; break;
+      case 4:
+        fifthElement = bar; break;
+      case 8:
+        ninthElement = bar; break;
+      }
+      arr2.AppendElement(bar);
+    }
+
+    base = Bar::sReleaseCalled;
+
+    arr2.TruncateLength(10);
+    ASSERT_EQ(Bar::sReleaseCalled, base + 10);
+    ASSERT_EQ(arr2.Length(), uint32_t(10));
+
+    arr2.RemoveElementAt(9);
+    ASSERT_EQ(Bar::sReleaseCalled, base + 11);
+    ASSERT_EQ(arr2.Length(), uint32_t(9));
+
+    arr2.RemoveElement(ninthElement);
+    ASSERT_EQ(Bar::sReleaseCalled, base + 12);
+    ASSERT_EQ(arr2.Length(), uint32_t(8));
+
+    arr2.RemoveElementsAt(2, 3);
+    ASSERT_EQ(Bar::sReleaseCalled, base + 15);
+    ASSERT_EQ(arr2.Length(), uint32_t(5));
+    for (uint32_t j = 0; j < arr2.Length(); ++j) {
+      ASSERT_NE(arr2.ElementAt(j), thirdElement);
+      ASSERT_NE(arr2.ElementAt(j), fourthElement);
+      ASSERT_NE(arr2.ElementAt(j), fifthElement);
+    }
+
+    arr2.RemoveElementsAt(4, 1);
+    ASSERT_EQ(Bar::sReleaseCalled, base + 16);
+    ASSERT_EQ(arr2.Length(), uint32_t(4));
+
+    arr2.Clear();
+    ASSERT_EQ(Bar::sReleaseCalled, base + 20);
+  }
+}
+
+TEST(COMArray, Destructor)
+{
+  int32_t base;
+  Bar::sReleaseCalled = 0;
+
+  {
+    nsCOMArray<IBar> arr2;
+
+    for (int32_t i = 0; i < 20; ++i) {
+      nsCOMPtr<IBar> bar  = new Bar(arr2);
+      arr2.AppendObject(bar);
+    }
+
+    base = Bar::sReleaseCalled;
+
+    // Let arr2 be destroyed
+  }
+  ASSERT_EQ(Bar::sReleaseCalled, base + 20);
+}
diff --git a/xpcom/tests/gtest/TestCOMPtr.cpp b/xpcom/tests/gtest/TestCOMPtr.cpp
new file mode 100644
index 000000000..e17331c65
--- /dev/null
+++ b/xpcom/tests/gtest/TestCOMPtr.cpp
@@ -0,0 +1,466 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCOMPtr.h"
+#include "gtest/gtest.h"
+
+#include "mozilla/Unused.h"
+
+#define NS_IFOO_IID \
+{ 0x6f7652e0,  0xee43, 0x11d1, \
+  { 0x9c, 0xc3, 0x00, 0x60, 0x08, 0x8c, 0xa6, 0xb3 } }
+
+namespace TestCOMPtr
+{
+
+class IFoo : public nsISupports
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_IFOO_IID)
+
+public:
+  IFoo();
+  // virtual dtor because IBar uses our Release()
+  virtual ~IFoo();
+
+  NS_IMETHOD_(MozExternalRefCountType) AddRef();
+  NS_IMETHOD_(MozExternalRefCountType) Release();
+  NS_IMETHOD QueryInterface( const nsIID&, void** );
+
+  unsigned int refcount_;
+
+  static int total_constructions_;
+  static int total_destructions_;
+  static int total_queries_;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(IFoo, NS_IFOO_IID)
+
+int IFoo::total_constructions_;
+int IFoo::total_destructions_;
+int IFoo::total_queries_;
+
+IFoo::IFoo()
+  : refcount_(0)
+{
+  ++total_constructions_;
+}
+
+IFoo::~IFoo()
+{
+  ++total_destructions_;
+}
+
+MozExternalRefCountType
+IFoo::AddRef()
+{
+  ++refcount_;
+  return refcount_;
+}
+
+MozExternalRefCountType
+IFoo::Release()
+{
+  int newcount = --refcount_;
+
+  if ( newcount == 0 )
+  {
+    delete this;
+  }
+
+  return newcount;
+}
+
+nsresult
+IFoo::QueryInterface( const nsIID& aIID, void** aResult )
+{
+  total_queries_++;
+
+  nsISupports* rawPtr = 0;
+  nsresult status = NS_OK;
+
+  if ( aIID.Equals(NS_GET_IID(IFoo)) )
+    rawPtr = this;
+  else
+  {
+    nsID iid_of_ISupports = NS_ISUPPORTS_IID;
+    if ( aIID.Equals(iid_of_ISupports) )
+      rawPtr = static_cast<nsISupports*>(this);
+    else
+      status = NS_ERROR_NO_INTERFACE;
+  }
+
+  NS_IF_ADDREF(rawPtr);
+  *aResult = rawPtr;
+
+  return status;
+}
+
+nsresult
+CreateIFoo( void** result )
+// a typical factory function (that calls AddRef)
+{
+  IFoo* foop = new IFoo;
+
+  foop->AddRef();
+  *result = foop;
+
+  return NS_OK;
+}
+
+void
+set_a_IFoo( nsCOMPtr<IFoo>* result )
+{
+  nsCOMPtr<IFoo> foop( do_QueryInterface(new IFoo) );
+  *result = foop;
+}
+
+nsCOMPtr<IFoo>
+return_a_IFoo()
+{
+  nsCOMPtr<IFoo> foop( do_QueryInterface(new IFoo) );
+  return foop;
+}
+
+#define NS_IBAR_IID \
+{ 0x6f7652e1,  0xee43, 0x11d1, \
+  { 0x9c, 0xc3, 0x00, 0x60, 0x08, 0x8c, 0xa6, 0xb3 } }
+
+class IBar : public IFoo
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_IBAR_IID)
+
+public:
+  IBar();
+  virtual ~IBar();
+
+  NS_IMETHOD QueryInterface( const nsIID&, void** );
+
+  static int total_destructions_;
+  static int total_queries_;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(IBar, NS_IBAR_IID)
+
+int IBar::total_destructions_;
+int IBar::total_queries_;
+
+IBar::IBar()
+{
+}
+
+IBar::~IBar()
+{
+  total_destructions_++;
+}
+
+nsresult
+IBar::QueryInterface( const nsID& aIID, void** aResult )
+{
+  total_queries_++;
+
+  nsISupports* rawPtr = 0;
+  nsresult status = NS_OK;
+
+  if ( aIID.Equals(NS_GET_IID(IBar)) )
+    rawPtr = this;
+  else if ( aIID.Equals(NS_GET_IID(IFoo)) )
+    rawPtr = static_cast<IFoo*>(this);
+  else
+  {
+    nsID iid_of_ISupports = NS_ISUPPORTS_IID;
+    if ( aIID.Equals(iid_of_ISupports) )
+      rawPtr = static_cast<nsISupports*>(this);
+    else
+      status = NS_ERROR_NO_INTERFACE;
+  }
+
+  NS_IF_ADDREF(rawPtr);
+  *aResult = rawPtr;
+
+  return status;
+}
+
+
+
+nsresult
+CreateIBar( void** result )
+  // a typical factory function (that calls AddRef)
+{
+  IBar* barp = new IBar;
+
+  barp->AddRef();
+  *result = barp;
+
+  return NS_OK;
+}
+
+void
+AnIFooPtrPtrContext( IFoo** )
+{
+}
+
+void
+AVoidPtrPtrContext( void** )
+{
+}
+
+void
+AnISupportsPtrPtrContext( nsISupports** )
+{
+}
+
+} // namespace TestCOMPtr
+
+using namespace TestCOMPtr;
+
+TEST(COMPtr, Bloat_Raw_Unsafe)
+{
+  // ER: I'm not sure what this is testing...
+  IBar* barP = 0;
+  nsresult rv = CreateIBar(reinterpret_cast<void**>(&barP));
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+  ASSERT_TRUE(barP);
+
+  IFoo* fooP = 0;
+  rv = barP->QueryInterface(NS_GET_IID(IFoo), reinterpret_cast<void**>(&fooP));
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+  ASSERT_TRUE(fooP);
+
+  NS_RELEASE(fooP);
+  NS_RELEASE(barP);
+}
+
+TEST(COMPtr, Bloat_Smart)
+{
+  // ER: I'm not sure what this is testing...
+  nsCOMPtr<IBar> barP;
+  nsresult rv = CreateIBar( getter_AddRefs(barP) );
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+  ASSERT_TRUE(barP);
+
+  nsCOMPtr<IFoo> fooP( do_QueryInterface(barP, &rv) );
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+  ASSERT_TRUE(fooP);
+}
+
+TEST(COMPtr, AddRefAndRelease)
+{
+  IFoo::total_constructions_ = 0;
+  IFoo::total_destructions_ = 0;
+  IBar::total_destructions_ = 0;
+
+  {
+    nsCOMPtr<IFoo> foop( do_QueryInterface(new IFoo) );
+    ASSERT_EQ(foop->refcount_, (unsigned int)1);
+    ASSERT_EQ(IFoo::total_constructions_, 1);
+    ASSERT_EQ(IFoo::total_destructions_, 0);
+
+    foop = do_QueryInterface(new IFoo);
+    ASSERT_EQ(foop->refcount_, (unsigned int)1);
+    ASSERT_EQ(IFoo::total_constructions_, 2);
+    ASSERT_EQ(IFoo::total_destructions_, 1);
+
+    // [Shouldn't compile] Is it a compile time error to try to |AddRef| by hand?
+    //foop->AddRef();
+
+    // [Shouldn't compile] Is it a compile time error to try to |Release| be hand?
+    //foop->Release();
+
+    // [Shouldn't compile] Is it a compile time error to try to |delete| an |nsCOMPtr|?
+    //delete foop;
+
+    static_cast<IFoo*>(foop)->AddRef();
+    ASSERT_EQ(foop->refcount_, (unsigned int)2);
+    ASSERT_EQ(IFoo::total_constructions_, 2);
+    ASSERT_EQ(IFoo::total_destructions_, 1);
+
+    static_cast<IFoo*>(foop)->Release();
+    ASSERT_EQ(foop->refcount_, (unsigned int)1);
+    ASSERT_EQ(IFoo::total_constructions_, 2);
+    ASSERT_EQ(IFoo::total_destructions_, 1);
+  }
+
+  ASSERT_EQ(IFoo::total_constructions_, 2);
+  ASSERT_EQ(IFoo::total_destructions_, 2);
+
+  {
+    nsCOMPtr<IFoo> foop( do_QueryInterface(new IBar) );
+    mozilla::Unused << foop;
+  }
+
+  ASSERT_EQ(IBar::total_destructions_, 1);
+}
+
+void Comparison()
+{
+  IFoo::total_constructions_ = 0;
+  IFoo::total_destructions_ = 0;
+
+  {
+    nsCOMPtr<IFoo> foo1p( do_QueryInterface(new IFoo) );
+    nsCOMPtr<IFoo> foo2p( do_QueryInterface(new IFoo) );
+
+    ASSERT_EQ(IFoo::total_constructions_, 2);
+
+    // Test != operator
+    ASSERT_NE(foo1p, foo2p);
+    ASSERT_NE(foo1p, foo2p.get());
+
+    // Test == operator
+    foo1p = foo2p;
+
+    ASSERT_EQ(IFoo::total_destructions_, 1);
+
+    ASSERT_EQ(foo1p, foo2p);
+    ASSERT_EQ(foo2p, foo2p.get());
+    ASSERT_EQ(foo2p.get(), foo2p);
+
+    // Test () operator
+    ASSERT_TRUE(foo1p);
+
+    ASSERT_EQ(foo1p->refcount_, (unsigned int)2);
+    ASSERT_EQ(foo2p->refcount_, (unsigned int)2);
+  }
+
+  ASSERT_EQ(IFoo::total_destructions_, 2);
+}
+
+void DontAddRef()
+{
+  {
+    IFoo* raw_foo1p = new IFoo;
+    raw_foo1p->AddRef();
+
+    IFoo* raw_foo2p = new IFoo;
+    raw_foo2p->AddRef();
+
+    nsCOMPtr<IFoo> foo1p( dont_AddRef(raw_foo1p) );
+    ASSERT_EQ(raw_foo1p, foo1p);
+    ASSERT_EQ(foo1p->refcount_, (unsigned int)1);
+
+    nsCOMPtr<IFoo> foo2p;
+    foo2p = dont_AddRef(raw_foo2p);
+    ASSERT_EQ(raw_foo2p, foo2p);
+    ASSERT_EQ(foo2p->refcount_, (unsigned int)1);
+  }
+}
+
+TEST(COMPtr, AssignmentHelpers)
+{
+  IFoo::total_constructions_ = 0;
+  IFoo::total_destructions_ = 0;
+
+  {
+    nsCOMPtr<IFoo> foop;
+    ASSERT_FALSE(foop);
+    CreateIFoo( nsGetterAddRefs<IFoo>(foop) );
+    ASSERT_TRUE(foop);
+  }
+
+  ASSERT_EQ(IFoo::total_constructions_, 1);
+  ASSERT_EQ(IFoo::total_destructions_, 1);
+
+  {
+    nsCOMPtr<IFoo> foop;
+    ASSERT_FALSE(foop);
+    CreateIFoo( getter_AddRefs(foop) );
+    ASSERT_TRUE(foop);
+  }
+
+  ASSERT_EQ(IFoo::total_constructions_, 2);
+  ASSERT_EQ(IFoo::total_destructions_, 2);
+
+  {
+    nsCOMPtr<IFoo> foop;
+    ASSERT_FALSE(foop);
+    set_a_IFoo(address_of(foop));
+    ASSERT_TRUE(foop);
+
+    ASSERT_EQ(IFoo::total_constructions_, 3);
+    ASSERT_EQ(IFoo::total_destructions_, 2);
+
+    foop = return_a_IFoo();
+    ASSERT_TRUE(foop);
+
+    ASSERT_EQ(IFoo::total_constructions_, 4);
+    ASSERT_EQ(IFoo::total_destructions_, 3);
+  }
+
+  ASSERT_EQ(IFoo::total_constructions_, 4);
+  ASSERT_EQ(IFoo::total_destructions_, 4);
+
+  {
+    nsCOMPtr<IFoo> fooP( do_QueryInterface(new IFoo) );
+    ASSERT_TRUE(fooP);
+
+    ASSERT_EQ(IFoo::total_constructions_, 5);
+    ASSERT_EQ(IFoo::total_destructions_, 4);
+
+    nsCOMPtr<IFoo> fooP2( fooP.forget() );
+    ASSERT_TRUE(fooP2);
+
+    ASSERT_EQ(IFoo::total_constructions_, 5);
+    ASSERT_EQ(IFoo::total_destructions_, 4);
+  }
+
+  ASSERT_EQ(IFoo::total_constructions_, 5);
+  ASSERT_EQ(IFoo::total_destructions_, 5);
+}
+
+TEST(COMPtr, QueryInterface)
+{
+  IFoo::total_queries_ = 0;
+  IBar::total_queries_ = 0;
+
+  {
+    nsCOMPtr<IFoo> fooP;
+    ASSERT_FALSE(fooP);
+    fooP = do_QueryInterface(new IFoo);
+    ASSERT_TRUE(fooP);
+    ASSERT_EQ(IFoo::total_queries_, 1);
+
+    nsCOMPtr<IFoo> foo2P;
+
+    // Test that |QueryInterface| _not_ called when assigning a smart-pointer
+    // of the same type.);
+    foo2P = fooP;
+    ASSERT_EQ(IFoo::total_queries_, 1);
+  }
+
+  {
+    nsCOMPtr<IBar> barP( do_QueryInterface(new IBar) );
+    ASSERT_EQ(IBar::total_queries_, 1);
+
+    // Test that |QueryInterface| is called when assigning a smart-pointer of
+    // a different type.
+    nsCOMPtr<IFoo> fooP( do_QueryInterface(barP) );
+    ASSERT_EQ(IBar::total_queries_, 2);
+    ASSERT_EQ(IFoo::total_queries_, 1);
+    ASSERT_TRUE(fooP);
+  }
+}
+
+TEST(COMPtr, GetterConversions)
+{
+  // This is just a compilation test. We add a few asserts to keep gtest happy.
+  {
+    nsCOMPtr<IFoo> fooP;
+    ASSERT_FALSE(fooP);
+
+    AnIFooPtrPtrContext( getter_AddRefs(fooP) );
+    AVoidPtrPtrContext( getter_AddRefs(fooP) );
+  }
+
+
+  {
+    nsCOMPtr<nsISupports> supportsP;
+    ASSERT_FALSE(supportsP);
+
+    AVoidPtrPtrContext( getter_AddRefs(supportsP) );
+    AnISupportsPtrPtrContext( getter_AddRefs(supportsP) );
+  }
+}
diff --git a/xpcom/tests/gtest/TestCOMPtrEq.cpp b/xpcom/tests/gtest/TestCOMPtrEq.cpp
new file mode 100644
index 000000000..b7513e2ae
--- /dev/null
+++ b/xpcom/tests/gtest/TestCOMPtrEq.cpp
@@ -0,0 +1,79 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * This attempts to test all the possible variations of |operator==|
+ * used with |nsCOMPtr|s.
+ */
+
+#include "nsCOMPtr.h"
+#include "gtest/gtest.h"
+
+#define NS_ICOMPTREQTESTFOO_IID \
+{0x8eb5bbef, 0xd1a3, 0x4659, \
+  {0x9c, 0xf6, 0xfd, 0xf3, 0xe4, 0xd2, 0x00, 0x0e}}
+
+class nsICOMPtrEqTestFoo : public nsISupports {
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_ICOMPTREQTESTFOO_IID)
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsICOMPtrEqTestFoo, NS_ICOMPTREQTESTFOO_IID)
+
+TEST(COMPtrEq, NullEquality)
+{
+  nsCOMPtr<nsICOMPtrEqTestFoo> s;
+  nsICOMPtrEqTestFoo* r = nullptr;
+  const nsCOMPtr<nsICOMPtrEqTestFoo> sc;
+  const nsICOMPtrEqTestFoo* rc = nullptr;
+  nsICOMPtrEqTestFoo* const rk = nullptr;
+  const nsICOMPtrEqTestFoo* const rkc = nullptr;
+  nsICOMPtrEqTestFoo* d = s;
+
+  ASSERT_EQ(s, s);
+  ASSERT_EQ(s, r);
+  ASSERT_EQ(s, sc);
+  ASSERT_EQ(s, rc);
+  ASSERT_EQ(s, rk);
+  ASSERT_EQ(s, rkc);
+  ASSERT_EQ(s, d);
+  ASSERT_EQ(r, s);
+  ASSERT_EQ(r, sc);
+  ASSERT_EQ(r, rc);
+  ASSERT_EQ(r, rk);
+  ASSERT_EQ(r, rkc);
+  ASSERT_EQ(r, d);
+  ASSERT_EQ(sc, s);
+  ASSERT_EQ(sc, r);
+  ASSERT_EQ(sc, sc);
+  ASSERT_EQ(sc, rc);
+  ASSERT_EQ(sc, rk);
+  ASSERT_EQ(sc, rkc);
+  ASSERT_EQ(sc, d);
+  ASSERT_EQ(rc, s);
+  ASSERT_EQ(rc, r);
+  ASSERT_EQ(rc, sc);
+  ASSERT_EQ(rc, rk);
+  ASSERT_EQ(rc, rkc);
+  ASSERT_EQ(rc, d);
+  ASSERT_EQ(rk, s);
+  ASSERT_EQ(rk, r);
+  ASSERT_EQ(rk, sc);
+  ASSERT_EQ(rk, rc);
+  ASSERT_EQ(rk, rkc);
+  ASSERT_EQ(rk, d);
+  ASSERT_EQ(rkc, s);
+  ASSERT_EQ(rkc, r);
+  ASSERT_EQ(rkc, sc);
+  ASSERT_EQ(rkc, rc);
+  ASSERT_EQ(rkc, rk);
+  ASSERT_EQ(rkc, d);
+  ASSERT_EQ(d, s);
+  ASSERT_EQ(d, r);
+  ASSERT_EQ(d, sc);
+  ASSERT_EQ(d, rc);
+  ASSERT_EQ(d, rk);
+  ASSERT_EQ(d, rkc);
+}
diff --git a/xpcom/tests/gtest/TestCRT.cpp b/xpcom/tests/gtest/TestCRT.cpp
new file mode 100644
index 000000000..9fa731404
--- /dev/null
+++ b/xpcom/tests/gtest/TestCRT.cpp
@@ -0,0 +1,86 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCRT.h"
+#include "nsString.h"
+#include "plstr.h"
+#include <stdlib.h>
+#include "gtest/gtest.h"
+
+namespace TestCRT {
+
+// The return from strcmp etc is only defined to be postive, zero or
+// negative. The magnitude of a non-zero return is irrelevant.
+int sign(int val) {
+  if (val == 0) {
+    return 0;
+  } else {
+    if (val > 0) {
+      return 1;
+    } else {
+      return -1;
+    }
+  }
+}
+
+
+// Verify that nsCRT versions of string comparison routines get the
+// same answers as the native non-unicode versions. We only pass in
+// iso-latin-1 strings, so the comparison must be valid.
+static void Check(const char* s1, const char* s2, int n)
+{
+  int clib = PL_strcmp(s1, s2);
+
+  int clib_n = PL_strncmp(s1, s2, n);
+
+  nsAutoString t1,t2; 
+  t1.AssignWithConversion(s1);
+  t2.AssignWithConversion(s2);
+  const char16_t* us1 = t1.get();
+  const char16_t* us2 = t2.get();
+
+  int u2 = nsCRT::strcmp(us1, us2);
+
+  int u2_n = nsCRT::strncmp(us1, us2, n);
+
+  EXPECT_EQ(sign(clib), sign(u2));
+  EXPECT_EQ(sign(clib), sign(u2_n));
+  EXPECT_EQ(sign(clib), sign(clib_n));
+}
+
+struct Test {
+  const char* s1;
+  const char* s2;
+  int n;
+};
+
+static Test tests[] = {
+  { "foo", "foo", 3 },
+  { "foo", "fo", 3 },
+
+  { "foo", "bar", 3 },
+  { "foo", "ba", 3 },
+
+  { "foo", "zap", 3 },
+  { "foo", "za", 3 },
+
+  { "bar", "foo", 3 },
+  { "bar", "fo", 3 },
+
+  { "bar", "foo", 3 },
+  { "bar", "fo", 3 },
+};
+#define NUM_TESTS int((sizeof(tests) / sizeof(tests[0])))
+
+TEST(CRT, main)
+{
+  TestCRT::Test* tp = tests;
+  for (int i = 0; i < NUM_TESTS; i++, tp++) {
+    Check(tp->s1, tp->s2, tp->n);
+  }
+}
+
+} // namespace TestCRT
diff --git a/xpcom/tests/gtest/TestCallTemplates.cpp b/xpcom/tests/gtest/TestCallTemplates.cpp
new file mode 100644
index 000000000..b8087e82b
--- /dev/null
+++ b/xpcom/tests/gtest/TestCallTemplates.cpp
@@ -0,0 +1,104 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim:cindent:ts=8:et:sw=4:
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * This test is NOT intended to be run.  It's a test to make sure
+ * a group of functions BUILD correctly.
+ */
+
+#include "nsISupportsUtils.h"
+#include "nsIWeakReference.h"
+#include "nsIComponentManager.h"
+#include "nsIServiceManager.h"
+#include "nsWeakReference.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsComponentManagerUtils.h"
+#include "nsServiceManagerUtils.h"
+#include "nsAutoPtr.h"
+#include "mozilla/Attributes.h"
+
+#define NS_ITESTSERVICE_IID \
+  {0x127b5253, 0x37b1, 0x43c7, \
+    { 0x96, 0x2b, 0xab, 0xf1, 0x2d, 0x22, 0x56, 0xae }}
+
+class NS_NO_VTABLE nsITestService : public nsISupports {
+  public: 
+    NS_DECLARE_STATIC_IID_ACCESSOR(NS_ITESTSERVICE_IID)
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsITestService, NS_ITESTSERVICE_IID)
+
+class nsTestService final : public nsITestService,
+                            public nsSupportsWeakReference
+{
+    ~nsTestService() {}
+  public:
+    NS_DECL_ISUPPORTS
+};
+
+NS_IMPL_ISUPPORTS(nsTestService, nsITestService, nsISupportsWeakReference)
+
+#define NS_TEST_SERVICE_CONTRACTID "@mozilla.org/test/testservice;1"
+#define NS_TEST_SERVICE_CID \
+  {0xa00c1406, 0x283a, 0x45c9, \
+    {0xae, 0xd2, 0x1a, 0xb6, 0xdd, 0xba, 0xfe, 0x53}}
+static NS_DEFINE_CID(kTestServiceCID, NS_TEST_SERVICE_CID);
+
+void JustTestingCompilation()
+{
+    /*
+     * NOTE:  This does NOT demonstrate how these functions are
+     * intended to be used.  They are intended for filling in out
+     * parameters that need to be |AddRef|ed.  I'm just too lazy
+     * to write lots of little getter functions for a test program
+     * when I don't need to.
+     */
+
+    NS_NOTREACHED("This test is not intended to run, only to compile!");
+
+    /* Test CallQueryInterface */
+
+    nsISupports *mySupportsPtr = reinterpret_cast<nsISupports*>(0x1000);
+
+    nsITestService *myITestService = nullptr;
+    CallQueryInterface(mySupportsPtr, &myITestService);
+
+    nsTestService *myTestService =
+        reinterpret_cast<nsTestService*>(mySupportsPtr);
+    nsISupportsWeakReference *mySupportsWeakRef;
+    CallQueryInterface(myTestService, &mySupportsWeakRef);
+
+    nsCOMPtr<nsISupports> mySupportsCOMPtr = mySupportsPtr;
+    CallQueryInterface(mySupportsCOMPtr, &myITestService);
+
+    RefPtr<nsTestService> myTestServiceRefPtr = myTestService;
+    CallQueryInterface(myTestServiceRefPtr, &mySupportsWeakRef);
+
+    /* Test CallQueryReferent */
+
+    nsIWeakReference *myWeakRef =
+        static_cast<nsIWeakReference*>(mySupportsPtr);
+    CallQueryReferent(myWeakRef, &myITestService);
+
+    /* Test CallCreateInstance */
+
+    CallCreateInstance(kTestServiceCID, mySupportsPtr, &myITestService);
+    CallCreateInstance(kTestServiceCID, &myITestService);
+    CallCreateInstance(NS_TEST_SERVICE_CONTRACTID, mySupportsPtr,
+                       &myITestService);
+    CallCreateInstance(NS_TEST_SERVICE_CONTRACTID, &myITestService);
+
+    /* Test CallGetService */
+    CallGetService(kTestServiceCID, &myITestService);
+    CallGetService(NS_TEST_SERVICE_CONTRACTID, &myITestService);
+
+    /* Test CallGetInterface */
+    nsIInterfaceRequestor *myInterfaceRequestor =
+        static_cast<nsIInterfaceRequestor*>(mySupportsPtr);
+    CallGetInterface(myInterfaceRequestor, &myITestService);
+}
diff --git a/xpcom/tests/gtest/TestCloneInputStream.cpp b/xpcom/tests/gtest/TestCloneInputStream.cpp
new file mode 100644
index 000000000..de4dd5ea3
--- /dev/null
+++ b/xpcom/tests/gtest/TestCloneInputStream.cpp
@@ -0,0 +1,200 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "gtest/gtest.h"
+#include "Helpers.h"
+#include "mozilla/Unused.h"
+#include "nsICloneableInputStream.h"
+#include "nsIMultiplexInputStream.h"
+#include "nsNetUtil.h"
+#include "nsStreamUtils.h"
+#include "nsStringStream.h"
+#include "nsComponentManagerUtils.h"
+
+TEST(CloneInputStream, InvalidInput)
+{
+  nsCOMPtr<nsIInputStream> clone;
+  nsresult rv = NS_CloneInputStream(nullptr, getter_AddRefs(clone));
+  ASSERT_TRUE(NS_FAILED(rv));
+  ASSERT_FALSE(clone);
+}
+
+TEST(CloneInputStream, CloneableInput)
+{
+  nsTArray<char> inputData;
+  testing::CreateData(4 * 1024, inputData);
+  nsDependentCSubstring inputString(inputData.Elements(), inputData.Length());
+
+  nsCOMPtr<nsIInputStream> stream;
+  nsresult rv = NS_NewCStringInputStream(getter_AddRefs(stream), inputString);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsIInputStream> clone;
+  rv = NS_CloneInputStream(stream, getter_AddRefs(clone));
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  testing::ConsumeAndValidateStream(stream, inputString);
+  testing::ConsumeAndValidateStream(clone, inputString);
+}
+
+TEST(CloneInputStream, NonCloneableInput_NoFallback)
+{
+  nsTArray<char> inputData;
+  testing::CreateData(4 * 1024, inputData);
+  nsDependentCSubstring inputString(inputData.Elements(), inputData.Length());
+
+  nsCOMPtr<nsIInputStream> base;
+  nsresult rv = NS_NewCStringInputStream(getter_AddRefs(base), inputString);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  // Take advantage of nsBufferedInputStream being non-cloneable right
+  // now.  If this changes in the future, then we need a different stream
+  // type in this test.
+  nsCOMPtr<nsIInputStream> stream;
+  rv = NS_NewBufferedInputStream(getter_AddRefs(stream), base, 4096);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsICloneableInputStream> cloneable = do_QueryInterface(stream);
+  ASSERT_TRUE(cloneable == nullptr);
+
+  nsCOMPtr<nsIInputStream> clone;
+  rv = NS_CloneInputStream(stream, getter_AddRefs(clone));
+  ASSERT_TRUE(NS_FAILED(rv));
+  ASSERT_TRUE(clone == nullptr);
+
+  testing::ConsumeAndValidateStream(stream, inputString);
+}
+
+TEST(CloneInputStream, NonCloneableInput_Fallback)
+{
+  nsTArray<char> inputData;
+  testing::CreateData(4 * 1024, inputData);
+  nsDependentCSubstring inputString(inputData.Elements(), inputData.Length());
+
+  nsCOMPtr<nsIInputStream> base;
+  nsresult rv = NS_NewCStringInputStream(getter_AddRefs(base), inputString);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  // Take advantage of nsBufferedInputStream being non-cloneable right
+  // now.  If this changes in the future, then we need a different stream
+  // type in this test.
+  nsCOMPtr<nsIInputStream> stream;
+  rv = NS_NewBufferedInputStream(getter_AddRefs(stream), base, 4096);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsICloneableInputStream> cloneable = do_QueryInterface(stream);
+  ASSERT_TRUE(cloneable == nullptr);
+
+  nsCOMPtr<nsIInputStream> clone;
+  nsCOMPtr<nsIInputStream> replacement;
+  rv = NS_CloneInputStream(stream, getter_AddRefs(clone),
+                           getter_AddRefs(replacement));
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+  ASSERT_TRUE(clone != nullptr);
+  ASSERT_TRUE(replacement != nullptr);
+  ASSERT_TRUE(stream.get() != replacement.get());
+  ASSERT_TRUE(clone.get() != replacement.get());
+
+  stream = replacement.forget();
+
+  // The stream is being copied asynchronously on the STS event target.  Spin
+  // a yield loop here until the data is available.  Yes, this is a bit hacky,
+  // but AFAICT, gtest does not support async test completion.
+  uint64_t available;
+  do {
+    mozilla::Unused << PR_Sleep(PR_INTERVAL_NO_WAIT);
+    rv = stream->Available(&available);
+    ASSERT_TRUE(NS_SUCCEEDED(rv));
+  } while(available < inputString.Length());
+
+  testing::ConsumeAndValidateStream(stream, inputString);
+  testing::ConsumeAndValidateStream(clone, inputString);
+}
+
+TEST(CloneInputStream, CloneMultiplexStream)
+{
+  nsCOMPtr<nsIMultiplexInputStream> stream =
+    do_CreateInstance("@mozilla.org/io/multiplex-input-stream;1");
+  ASSERT_TRUE(stream);
+
+  nsTArray<char> inputData;
+  testing::CreateData(1024, inputData);
+  for (uint32_t i = 0; i < 2; ++i) {
+    nsCString inputString(inputData.Elements(), inputData.Length());
+
+    nsCOMPtr<nsIInputStream> base;
+    nsresult rv = NS_NewCStringInputStream(getter_AddRefs(base), inputString);
+    ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+    rv = stream->AppendStream(base);
+    ASSERT_TRUE(NS_SUCCEEDED(rv));
+  }
+
+  // Unread stream should clone successfully.
+  nsTArray<char> doubled;
+  doubled.AppendElements(inputData);
+  doubled.AppendElements(inputData);
+
+  nsCOMPtr<nsIInputStream> clone;
+  nsresult rv = NS_CloneInputStream(stream, getter_AddRefs(clone));
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+  testing::ConsumeAndValidateStream(clone, doubled);
+
+  // Stream that has been read should fail.
+  char buffer[512];
+  uint32_t read;
+  rv = stream->Read(buffer, 512, &read);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsIInputStream> clone2;
+  rv = NS_CloneInputStream(stream, getter_AddRefs(clone2));
+  ASSERT_TRUE(NS_FAILED(rv));
+}
+
+TEST(CloneInputStream, CloneMultiplexStreamPartial)
+{
+  nsCOMPtr<nsIMultiplexInputStream> stream =
+    do_CreateInstance("@mozilla.org/io/multiplex-input-stream;1");
+  ASSERT_TRUE(stream);
+
+  nsTArray<char> inputData;
+  testing::CreateData(1024, inputData);
+  for (uint32_t i = 0; i < 2; ++i) {
+    nsCString inputString(inputData.Elements(), inputData.Length());
+
+    nsCOMPtr<nsIInputStream> base;
+    nsresult rv = NS_NewCStringInputStream(getter_AddRefs(base), inputString);
+    ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+    rv = stream->AppendStream(base);
+    ASSERT_TRUE(NS_SUCCEEDED(rv));
+  }
+
+  // Fail when first stream read, but second hasn't been started.
+  char buffer[1024];
+  uint32_t read;
+  nsresult rv = stream->Read(buffer, 1024, &read);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsIInputStream> clone;
+  rv = NS_CloneInputStream(stream, getter_AddRefs(clone));
+  ASSERT_TRUE(NS_FAILED(rv));
+
+  // Fail after beginning read of second stream.
+  rv = stream->Read(buffer, 512, &read);
+  ASSERT_TRUE(NS_SUCCEEDED(rv) && read == 512);
+
+  rv = NS_CloneInputStream(stream, getter_AddRefs(clone));
+  ASSERT_TRUE(NS_FAILED(rv));
+
+  // Fail at the end.
+  nsAutoCString consumed;
+  rv = NS_ConsumeStream(stream, UINT32_MAX, consumed);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  rv = NS_CloneInputStream(stream, getter_AddRefs(clone));
+  ASSERT_TRUE(NS_FAILED(rv));
+}
diff --git a/xpcom/tests/gtest/TestDeadlockDetector.cpp b/xpcom/tests/gtest/TestDeadlockDetector.cpp
new file mode 100644
index 000000000..646ee3e1d
--- /dev/null
+++ b/xpcom/tests/gtest/TestDeadlockDetector.cpp
@@ -0,0 +1,322 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: sw=4 ts=4 et :
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ArrayUtils.h"
+
+#include "prthread.h"
+
+#include "nsTArray.h"
+#include "nsMemory.h"
+
+#include "mozilla/CondVar.h"
+#include "mozilla/ReentrantMonitor.h"
+#include "mozilla/Mutex.h"
+
+#ifdef MOZ_CRASHREPORTER
+#include "nsCOMPtr.h"
+#include "nsICrashReporter.h"
+#include "nsServiceManagerUtils.h"
+#endif
+
+#include "gtest/gtest.h"
+
+using namespace mozilla;
+
+static PRThread*
+spawn(void (*run)(void*), void* arg)
+{
+    return PR_CreateThread(PR_SYSTEM_THREAD,
+                           run,
+                           arg,
+                           PR_PRIORITY_NORMAL,
+                           PR_GLOBAL_THREAD,
+                           PR_JOINABLE_THREAD,
+                           0);
+}
+
+// This global variable is defined in toolkit/xre/nsSigHandlers.cpp.
+extern unsigned int _gdb_sleep_duration;
+
+/**
+ * Simple test fixture that makes sure the gdb sleep setup in the
+ * ah crap handler is bypassed during the death tests.
+ */
+class DeadlockDetectorTest : public ::testing::Test
+{
+protected:
+  void SetUp() final {
+    mOldSleepDuration = _gdb_sleep_duration;
+    _gdb_sleep_duration = 0;
+  }
+
+  void TearDown() final {
+    _gdb_sleep_duration = mOldSleepDuration;
+  }
+
+private:
+  unsigned int mOldSleepDuration;
+};
+
+void DisableCrashReporter()
+{
+#ifdef MOZ_CRASHREPORTER
+    nsCOMPtr<nsICrashReporter> crashreporter =
+        do_GetService("@mozilla.org/toolkit/crash-reporter;1");
+    if (crashreporter) {
+      crashreporter->SetEnabled(false);
+    }
+#endif
+}
+
+//-----------------------------------------------------------------------------
+// Single-threaded sanity tests
+
+// Stupidest possible deadlock.
+int
+Sanity_Child()
+{
+    DisableCrashReporter();
+
+    mozilla::Mutex m1("dd.sanity.m1");
+    m1.Lock();
+    m1.Lock();
+    return 0;                  // not reached
+}
+
+TEST_F(DeadlockDetectorTest, SanityDeathTest)
+{
+    const char* const regex =
+        "###!!! ERROR: Potential deadlock detected.*"
+        "=== Cyclical dependency starts at.*--- Mutex : dd.sanity.m1.*"
+        "=== Cycle completed at.*--- Mutex : dd.sanity.m1.*"
+        "###!!! Deadlock may happen NOW!.*" // better catch these easy cases...
+        "###!!! ASSERTION: Potential deadlock detected.*";
+
+    ASSERT_DEATH_IF_SUPPORTED(Sanity_Child(), regex);
+}
+
+// Slightly less stupid deadlock.
+int
+Sanity2_Child()
+{
+    DisableCrashReporter();
+
+    mozilla::Mutex m1("dd.sanity2.m1");
+    mozilla::Mutex m2("dd.sanity2.m2");
+    m1.Lock();
+    m2.Lock();
+    m1.Lock();
+    return 0;                  // not reached
+}
+
+TEST_F(DeadlockDetectorTest, Sanity2DeathTest)
+{
+    const char* const regex =
+        "###!!! ERROR: Potential deadlock detected.*"
+        "=== Cyclical dependency starts at.*--- Mutex : dd.sanity2.m1.*"
+        "--- Next dependency:.*--- Mutex : dd.sanity2.m2.*"
+        "=== Cycle completed at.*--- Mutex : dd.sanity2.m1.*"
+        "###!!! Deadlock may happen NOW!.*" // better catch these easy cases...
+        "###!!! ASSERTION: Potential deadlock detected.*";
+
+    ASSERT_DEATH_IF_SUPPORTED(Sanity2_Child(), regex);
+}
+
+int
+Sanity3_Child()
+{
+    DisableCrashReporter();
+
+    mozilla::Mutex m1("dd.sanity3.m1");
+    mozilla::Mutex m2("dd.sanity3.m2");
+    mozilla::Mutex m3("dd.sanity3.m3");
+    mozilla::Mutex m4("dd.sanity3.m4");
+
+    m1.Lock();
+    m2.Lock();
+    m3.Lock();
+    m4.Lock();
+    m4.Unlock();
+    m3.Unlock();
+    m2.Unlock();
+    m1.Unlock();
+
+    m4.Lock();
+    m1.Lock();
+    return 0;
+}
+
+TEST_F(DeadlockDetectorTest, Sanity3DeathTest)
+{
+    const char* const regex =
+        "###!!! ERROR: Potential deadlock detected.*"
+        "=== Cyclical dependency starts at.*--- Mutex : dd.sanity3.m1.*"
+        "--- Next dependency:.*--- Mutex : dd.sanity3.m2.*"
+        "--- Next dependency:.*--- Mutex : dd.sanity3.m3.*"
+        "--- Next dependency:.*--- Mutex : dd.sanity3.m4.*"
+        "=== Cycle completed at.*--- Mutex : dd.sanity3.m1.*"
+        "###!!! ASSERTION: Potential deadlock detected.*";
+
+    ASSERT_DEATH_IF_SUPPORTED(Sanity3_Child(), regex);
+}
+
+int
+Sanity4_Child()
+{
+    DisableCrashReporter();
+
+    mozilla::ReentrantMonitor m1("dd.sanity4.m1");
+    mozilla::Mutex m2("dd.sanity4.m2");
+    m1.Enter();
+    m2.Lock();
+    m1.Enter();
+    return 0;
+}
+
+TEST_F(DeadlockDetectorTest, Sanity4DeathTest)
+{
+    const char* const regex =
+        "Re-entering ReentrantMonitor after acquiring other resources.*"
+        "###!!! ERROR: Potential deadlock detected.*"
+        "=== Cyclical dependency starts at.*--- ReentrantMonitor : dd.sanity4.m1.*"
+        "--- Next dependency:.*--- Mutex : dd.sanity4.m2.*"
+        "=== Cycle completed at.*--- ReentrantMonitor : dd.sanity4.m1.*"
+        "###!!! ASSERTION: Potential deadlock detected.*";
+    ASSERT_DEATH_IF_SUPPORTED(Sanity4_Child(), regex);
+}
+
+//-----------------------------------------------------------------------------
+// Multithreaded tests
+
+/**
+ * Helper for passing state to threads in the multithread tests.
+ */
+struct ThreadState
+{
+  /**
+   * Locks to use during the test. This is just a reference and is owned by
+   * the main test thread.
+   */
+  const nsTArray<mozilla::Mutex*>& locks;
+
+  /**
+   * Integer argument used to identify each thread.
+   */
+  int id;
+};
+
+static void
+TwoThreads_thread(void* arg)
+{
+    ThreadState* state = static_cast<ThreadState*>(arg);
+
+    mozilla::Mutex* ttM1 = state->locks[0];
+    mozilla::Mutex* ttM2 = state->locks[1];
+
+    if (state->id) {
+        ttM1->Lock();
+        ttM2->Lock();
+        ttM2->Unlock();
+        ttM1->Unlock();
+    }
+    else {
+        ttM2->Lock();
+        ttM1->Lock();
+        ttM1->Unlock();
+        ttM2->Unlock();
+    }
+}
+
+int
+TwoThreads_Child()
+{
+    DisableCrashReporter();
+
+    nsTArray<mozilla::Mutex*> locks = {
+      new mozilla::Mutex("dd.twothreads.m1"),
+      new mozilla::Mutex("dd.twothreads.m2")
+    };
+
+    ThreadState state_1 {locks, 0};
+    PRThread* t1 = spawn(TwoThreads_thread, &state_1);
+    PR_JoinThread(t1);
+
+    ThreadState state_2 {locks, 1};
+    PRThread* t2 = spawn(TwoThreads_thread, &state_2);
+    PR_JoinThread(t2);
+
+    for (auto& lock : locks) {
+      delete lock;
+    }
+
+    return 0;
+}
+
+TEST_F(DeadlockDetectorTest, TwoThreadsDeathTest)
+{
+    const char* const regex =
+        "###!!! ERROR: Potential deadlock detected.*"
+        "=== Cyclical dependency starts at.*--- Mutex : dd.twothreads.m2.*"
+        "--- Next dependency:.*--- Mutex : dd.twothreads.m1.*"
+        "=== Cycle completed at.*--- Mutex : dd.twothreads.m2.*"
+        "###!!! ASSERTION: Potential deadlock detected.*";
+
+    ASSERT_DEATH_IF_SUPPORTED(TwoThreads_Child(), regex);
+}
+
+static void
+ContentionNoDeadlock_thread(void* arg)
+{
+    const uint32_t K = 100000;
+
+    ThreadState* state = static_cast<ThreadState*>(arg);
+    int32_t starti = static_cast<int32_t>(state->id);
+    auto& cndMs = state->locks;
+
+    for (uint32_t k = 0; k < K; ++k) {
+        for (int32_t i = starti; i < (int32_t)cndMs.Length(); ++i)
+            cndMs[i]->Lock();
+        // comment out the next two lines for deadlocking fun!
+        for (int32_t i = cndMs.Length() - 1; i >= starti; --i)
+            cndMs[i]->Unlock();
+
+        starti = (starti + 1) % 3;
+    }
+}
+
+int
+ContentionNoDeadlock_Child()
+{
+    const size_t kMutexCount = 4;
+
+    PRThread* threads[3];
+    nsTArray<mozilla::Mutex*> locks;
+    ThreadState states[] = {
+      { locks, 0 },
+      { locks, 1 },
+      { locks, 2 }
+    };
+
+    for (uint32_t i = 0; i < kMutexCount; ++i)
+        locks.AppendElement(new mozilla::Mutex("dd.cnd.ms"));
+
+    for (int32_t i = 0; i < (int32_t) ArrayLength(threads); ++i)
+        threads[i] = spawn(ContentionNoDeadlock_thread, states + i);
+
+    for (uint32_t i = 0; i < ArrayLength(threads); ++i)
+        PR_JoinThread(threads[i]);
+
+    for (uint32_t i = 0; i < locks.Length(); ++i)
+        delete locks[i];
+
+    return 0;
+}
+
+TEST_F(DeadlockDetectorTest, ContentionNoDeadlock)
+{
+  // Just check that this test runs to completion.
+  ASSERT_EQ(ContentionNoDeadlock_Child(), 0);
+}
diff --git a/xpcom/tests/gtest/TestDeadlockDetectorScalability.cpp b/xpcom/tests/gtest/TestDeadlockDetectorScalability.cpp
new file mode 100644
index 000000000..e25217223
--- /dev/null
+++ b/xpcom/tests/gtest/TestDeadlockDetectorScalability.cpp
@@ -0,0 +1,170 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: sw=4 ts=4 et :
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Avoid DMD-specific parts of MOZ_DEFINE_MALLOC_SIZE_OF
+#undef MOZ_DMD
+
+#include "nsIMemoryReporter.h"
+#include "mozilla/Mutex.h"
+
+#include "gtest/gtest.h"
+
+//-----------------------------------------------------------------------------
+
+static void
+AllocLockRecurseUnlockFree(int i)
+{
+    if (0 == i)
+        return;
+
+    mozilla::Mutex* lock = new mozilla::Mutex("deadlockDetector.scalability.t1");
+    {
+        mozilla::MutexAutoLock _(*lock);
+        AllocLockRecurseUnlockFree(i - 1);
+    }
+    delete lock;
+}
+
+// This test creates a resource dependency chain N elements long, then
+// frees all the resources in the chain.
+TEST(DeadlockDetectorScalability, LengthNDepChain)
+{
+    const int N = 1 << 14; // 16K
+    AllocLockRecurseUnlockFree(N);
+    ASSERT_TRUE(true);
+}
+
+//-----------------------------------------------------------------------------
+
+// This test creates a single lock that is ordered < N resources, then
+// repeatedly exercises this order k times.
+//
+// NB: It takes a minute or two to run so it is disabled by default.
+TEST(DeadlockDetectorScalability, DISABLED_OneLockNDeps)
+{
+    // NB: Using a larger test size to stress our traversal logic.
+    const int N = 1 << 17; // 131k
+    const int K = 100;
+
+    mozilla::Mutex* lock = new mozilla::Mutex("deadlockDetector.scalability.t2.master");
+    mozilla::Mutex** locks = new mozilla::Mutex*[N];
+    if (!locks)
+        NS_RUNTIMEABORT("couldn't allocate lock array");
+
+    for (int i = 0; i < N; ++i)
+        locks[i] =
+            new mozilla::Mutex("deadlockDetector.scalability.t2.dep");
+
+    // establish orders
+    {mozilla::MutexAutoLock m(*lock);
+        for (int i = 0; i < N; ++i)
+            mozilla::MutexAutoLock s(*locks[i]);
+    }
+
+    // exercise order check
+    {mozilla::MutexAutoLock m(*lock);
+        for (int i = 0; i < K; ++i)
+            for (int j = 0; j < N; ++j)
+                mozilla::MutexAutoLock s(*locks[i]);
+    }
+
+    for (int i = 0; i < N; ++i)
+        delete locks[i];
+    delete[] locks;
+
+    ASSERT_TRUE(true);
+}
+
+//-----------------------------------------------------------------------------
+
+// This test creates N resources and adds the theoretical maximum number
+// of dependencies, O(N^2).  It then repeats that sequence of
+// acquisitions k times.  Finally, all resources are freed.
+//
+// It's very difficult to perform well on this test.  It's put forth as a
+// challenge problem.
+
+TEST(DeadlockDetectorScalability, MaxDepsNsq)
+{
+    const int N = 1 << 10; // 1k
+    const int K = 10;
+
+    mozilla::Mutex** locks = new mozilla::Mutex*[N];
+    if (!locks)
+        NS_RUNTIMEABORT("couldn't allocate lock array");
+
+    for (int i = 0; i < N; ++i)
+        locks[i] = new mozilla::Mutex("deadlockDetector.scalability.t3");
+
+    for (int i = 0; i < N; ++i) {
+        mozilla::MutexAutoLock al1(*locks[i]);
+        for (int j = i+1; j < N; ++j)
+            mozilla::MutexAutoLock al2(*locks[j]);
+    }
+
+    for (int i = 0; i < K; ++i) {
+        for (int j = 0; j < N; ++j) {
+            mozilla::MutexAutoLock al1(*locks[j]);
+            for (int k = j+1; k < N; ++k)
+                mozilla::MutexAutoLock al2(*locks[k]);
+        }
+    }
+
+    for (int i = 0; i < N; ++i)
+        delete locks[i];
+    delete[] locks;
+
+    ASSERT_TRUE(true);
+}
+
+//-----------------------------------------------------------------------------
+
+// This test creates a single lock that is ordered < N resources. The
+// resources are allocated, exercised K times, and deallocated one at
+// a time.
+
+TEST(DeadlockDetectorScalability, OneLockNDepsUsedSeveralTimes)
+{
+    const size_t N = 1 << 17; // 131k
+    const size_t K = 3;
+
+    // Create master lock.
+    mozilla::Mutex* lock_1 = new mozilla::Mutex("deadlockDetector.scalability.t4.master");
+    for (size_t n = 0; n < N; n++) {
+        // Create child lock.
+        mozilla::Mutex* lock_2 = new mozilla::Mutex("deadlockDetector.scalability.t4.child");
+
+        // First lock the master.
+        mozilla::MutexAutoLock m(*lock_1);
+
+        // Now lock and unlock the child a few times.
+        for (size_t k = 0; k < K; k++) {
+            mozilla::MutexAutoLock c(*lock_2);
+        }
+
+        // Destroy the child lock.
+        delete lock_2;
+    }
+
+    // Cleanup the master lock.
+    delete lock_1;
+
+    ASSERT_TRUE(true);
+}
+
+//-----------------------------------------------------------------------------
+
+MOZ_DEFINE_MALLOC_SIZE_OF(DeadlockDetectorMallocSizeOf)
+
+// This is a simple test that exercises the deadlock detector memory reporting
+// functionality.
+TEST(DeadlockDetectorScalability, SizeOf)
+{
+    size_t memory_used = mozilla::BlockingResourceBase::SizeOfDeadlockDetector(
+        DeadlockDetectorMallocSizeOf);
+
+    ASSERT_GT(memory_used, size_t(0));
+}
diff --git a/xpcom/tests/gtest/TestEncoding.cpp b/xpcom/tests/gtest/TestEncoding.cpp
new file mode 100644
index 000000000..0671284ee
--- /dev/null
+++ b/xpcom/tests/gtest/TestEncoding.cpp
@@ -0,0 +1,109 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdlib.h>
+#include "nsString.h"
+#include "gtest/gtest.h"
+
+TEST(Encoding, GoodSurrogatePair)
+{
+  // When this string is decoded, the surrogate pair is U+10302 and the rest of
+  // the string is specified by indexes 2 onward.
+  const char16_t goodPairData[] = {  0xD800, 0xDF02, 0x65, 0x78, 0x0 };
+  nsDependentString goodPair16(goodPairData);
+
+  uint32_t byteCount = 0;
+  char* goodPair8 = ToNewUTF8String(goodPair16, &byteCount);
+  EXPECT_TRUE(!!goodPair8);
+
+  EXPECT_EQ(byteCount, 6u);
+
+  const unsigned char expected8[] =
+    { 0xF0, 0x90, 0x8C, 0x82, 0x65, 0x78, 0x0 };
+  EXPECT_EQ(0, memcmp(expected8, goodPair8, sizeof(expected8)));
+
+  // This takes a different code path from the above, so test it to make sure
+  // the UTF-16 enumeration remains in sync with the UTF-8 enumeration.
+  nsDependentCString expected((const char*)expected8);
+  EXPECT_EQ(0, CompareUTF8toUTF16(expected, goodPair16));
+
+  free(goodPair8);
+}
+
+TEST(Encoding, BackwardsSurrogatePair)
+{
+  // When this string is decoded, the two surrogates are wrongly ordered and
+  // must each be interpreted as U+FFFD.
+  const char16_t backwardsPairData[] = { 0xDDDD, 0xD863, 0x65, 0x78, 0x0 };
+  nsDependentString backwardsPair16(backwardsPairData);
+
+  uint32_t byteCount = 0;
+  char* backwardsPair8 = ToNewUTF8String(backwardsPair16, &byteCount);
+  EXPECT_TRUE(!!backwardsPair8);
+
+  EXPECT_EQ(byteCount, 8u);
+
+  const unsigned char expected8[] =
+    { 0xEF, 0xBF, 0xBD, 0xEF, 0xBF, 0xBD, 0x65, 0x78, 0x0 };
+  EXPECT_EQ(0, memcmp(expected8, backwardsPair8, sizeof(expected8)));
+
+  // This takes a different code path from the above, so test it to make sure
+  // the UTF-16 enumeration remains in sync with the UTF-8 enumeration.
+  nsDependentCString expected((const char*)expected8);
+  EXPECT_EQ(0, CompareUTF8toUTF16(expected, backwardsPair16));
+
+  free(backwardsPair8);
+}
+
+TEST(Encoding, MalformedUTF16OrphanHighSurrogate)
+{
+  // When this string is decoded, the high surrogate should be replaced and the
+  // rest of the string is specified by indexes 1 onward.
+  const char16_t highSurrogateData[] = { 0xD863, 0x74, 0x65, 0x78, 0x74, 0x0 };
+  nsDependentString highSurrogate16(highSurrogateData);
+
+  uint32_t byteCount = 0;
+  char* highSurrogate8 = ToNewUTF8String(highSurrogate16, &byteCount);
+  EXPECT_TRUE(!!highSurrogate8);
+
+  EXPECT_EQ(byteCount, 7u);
+
+  const unsigned char expected8[] =
+    { 0xEF, 0xBF, 0xBD, 0x74, 0x65, 0x78, 0x74, 0x0 };
+  EXPECT_EQ(0, memcmp(expected8, highSurrogate8, sizeof(expected8)));
+
+  // This takes a different code path from the above, so test it to make sure
+  // the UTF-16 enumeration remains in sync with the UTF-8 enumeration.
+  nsDependentCString expected((const char*)expected8);
+  EXPECT_EQ(0, CompareUTF8toUTF16(expected, highSurrogate16));
+
+  free(highSurrogate8);
+}
+
+TEST(Encoding, MalformedUTF16OrphanLowSurrogate)
+{
+  // When this string is decoded, the low surrogate should be replaced and the
+  // rest of the string is specified by indexes 1 onward.
+  const char16_t lowSurrogateData[] = { 0xDDDD, 0x74, 0x65, 0x78, 0x74, 0x0 };
+  nsDependentString lowSurrogate16(lowSurrogateData);
+
+  uint32_t byteCount = 0;
+  char* lowSurrogate8 = ToNewUTF8String(lowSurrogate16, &byteCount);
+  EXPECT_TRUE(!!lowSurrogate8);
+
+  EXPECT_EQ(byteCount, 7u);
+
+  const unsigned char expected8[] =
+    { 0xEF, 0xBF, 0xBD, 0x74, 0x65, 0x78, 0x74, 0x0 };
+  EXPECT_EQ(0, memcmp(expected8, lowSurrogate8, sizeof(expected8)));
+
+  // This takes a different code path from the above, so test it to make sure
+  // the UTF-16 enumeration remains in sync with the UTF-8 enumeration.
+  nsDependentCString expected((const char*)expected8);
+  EXPECT_EQ(0, CompareUTF8toUTF16(expected, lowSurrogate16));
+
+  free(lowSurrogate8);
+}
diff --git a/xpcom/tests/gtest/TestEscapeURL.cpp b/xpcom/tests/gtest/TestEscapeURL.cpp
new file mode 100644
index 000000000..2a8faf5f0
--- /dev/null
+++ b/xpcom/tests/gtest/TestEscapeURL.cpp
@@ -0,0 +1,69 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsEscape.h"
+#include "gtest/gtest.h"
+
+using namespace mozilla;
+
+// Testing for failure here would be somewhat hard in automation. Locally you
+// could use something like ulimit to create a failure.
+
+TEST(EscapeURL, FallibleNoEscape)
+{
+  // Tests the fallible version of NS_EscapeURL works as expected when no
+  // escaping is necessary.
+  nsCString toEscape("data:,Hello%2C%20World!");
+  nsCString escaped;
+  nsresult rv = NS_EscapeURL(toEscape, esc_OnlyNonASCII, escaped, fallible);
+  EXPECT_EQ(rv, NS_OK);
+  // Nothing should have been escaped, they should be the same string.
+  EXPECT_STREQ(toEscape.BeginReading(), escaped.BeginReading());
+  // We expect them to point at the same buffer.
+  EXPECT_EQ(toEscape.BeginReading(), escaped.BeginReading());
+}
+
+TEST(EscapeURL, FallibleEscape)
+{
+  // Tests the fallible version of NS_EscapeURL works as expected when
+  // escaping is necessary.
+  nsCString toEscape("data:,Hello%2C%20World!\xC4\x9F");
+  nsCString escaped;
+  nsresult rv = NS_EscapeURL(toEscape, esc_OnlyNonASCII, escaped, fallible);
+  EXPECT_EQ(rv, NS_OK);
+  EXPECT_STRNE(toEscape.BeginReading(), escaped.BeginReading());
+  const char* const kExpected = "data:,Hello%2C%20World!%C4%9F";
+  EXPECT_STREQ(escaped.BeginReading(), kExpected);
+}
+
+TEST(EscapeURL, BadEscapeSequences)
+{
+  {
+    char bad[] = "%s\0fa";
+
+    int32_t count = nsUnescapeCount(bad);
+    EXPECT_EQ(count, 2);
+    EXPECT_STREQ(bad, "%s");
+  }
+  {
+    char bad[] = "%a";
+    int32_t count = nsUnescapeCount(bad);
+    EXPECT_EQ(count, 2);
+    EXPECT_STREQ(bad, "%a");
+  }
+  {
+    char bad[] = "%";
+    int32_t count = nsUnescapeCount(bad);
+    EXPECT_EQ(count, 1);
+    EXPECT_STREQ(bad, "%");
+  }
+  {
+    char bad[] = "%s/%s";
+    int32_t count = nsUnescapeCount(bad);
+    EXPECT_EQ(count, 5);
+    EXPECT_STREQ(bad, "%s/%s");
+  }
+}
diff --git a/xpcom/tests/gtest/TestExpirationTracker.cpp b/xpcom/tests/gtest/TestExpirationTracker.cpp
new file mode 100644
index 000000000..a6a0e146c
--- /dev/null
+++ b/xpcom/tests/gtest/TestExpirationTracker.cpp
@@ -0,0 +1,185 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <prthread.h>
+#include "nsExpirationTracker.h"
+#include "nsMemory.h"
+#include "nsAutoPtr.h"
+#include "nsString.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsDirectoryServiceUtils.h"
+#include "nsComponentManagerUtils.h"
+#include "nsXPCOM.h"
+#include "nsIFile.h"
+#include "prinrval.h"
+#include "nsThreadUtils.h"
+#include "mozilla/UniquePtr.h"
+#include "gtest/gtest.h"
+
+namespace TestExpirationTracker {
+
+struct Object {
+  Object() : mExpired(false) { Touch(); }
+  void Touch() { mLastUsed = PR_IntervalNow(); mExpired = false; }
+
+  nsExpirationState mExpiration;
+  nsExpirationState* GetExpirationState() { return &mExpiration; }
+
+  PRIntervalTime mLastUsed;
+  bool           mExpired;
+};
+
+static bool error;
+static uint32_t periodMS = 100;
+static uint32_t ops = 1000;
+static uint32_t iterations = 2;
+static bool logging = 0;
+static uint32_t sleepPeriodMS = 50;
+static uint32_t slackMS = 30; // allow this much error
+
+template <uint32_t K> class Tracker : public nsExpirationTracker<Object,K> {
+public:
+  Tracker() : nsExpirationTracker<Object,K>(periodMS, "Tracker") {
+    Object* obj = new Object();
+    mUniverse.AppendElement(obj);
+    LogAction(obj, "Created");
+  }
+
+  nsTArray<mozilla::UniquePtr<Object>> mUniverse;
+
+  void LogAction(Object* aObj, const char* aAction) {
+    if (logging) {
+      printf("%d %p(%d): %s\n", PR_IntervalNow(),
+             static_cast<void*>(aObj), aObj->mLastUsed, aAction);
+    }
+  }
+
+  void DoRandomOperation() {
+    Object* obj;
+    switch (rand() & 0x7) {
+    case 0: {
+      if (mUniverse.Length() < 50) {
+        obj = new Object();
+        mUniverse.AppendElement(obj);
+        nsExpirationTracker<Object,K>::AddObject(obj);
+        LogAction(obj, "Created and added");
+      }
+      break;
+    }
+    case 4: {
+      if (mUniverse.Length() < 50) {
+        obj = new Object();
+        mUniverse.AppendElement(obj);
+        LogAction(obj, "Created");
+      }
+      break;
+    }
+    case 1: {
+      UniquePtr<Object>& objref = mUniverse[uint32_t(rand())%mUniverse.Length()];
+      if (objref->mExpiration.IsTracked()) {
+        nsExpirationTracker<Object,K>::RemoveObject(objref.get());
+        LogAction(objref.get(), "Removed");
+      }
+      break;
+    }
+    case 2: {
+      UniquePtr<Object>& objref = mUniverse[uint32_t(rand())%mUniverse.Length()];
+      if (!objref->mExpiration.IsTracked()) {
+        objref->Touch();
+        nsExpirationTracker<Object,K>::AddObject(objref.get());
+        LogAction(objref.get(), "Added");
+      }
+      break;
+    }
+    case 3: {
+      UniquePtr<Object>& objref = mUniverse[uint32_t(rand())%mUniverse.Length()];
+      if (objref->mExpiration.IsTracked()) {
+        objref->Touch();
+        nsExpirationTracker<Object,K>::MarkUsed(objref.get());
+        LogAction(objref.get(), "Marked used");
+      }
+      break;
+    }
+    }
+  }
+  
+protected:
+  void NotifyExpired(Object* aObj) {
+    LogAction(aObj, "Expired");
+    PRIntervalTime now = PR_IntervalNow();
+    uint32_t timeDiffMS = (now - aObj->mLastUsed)*1000/PR_TicksPerSecond();
+    // See the comment for NotifyExpired in nsExpirationTracker.h for these
+    // bounds
+    uint32_t lowerBoundMS = (K-1)*periodMS - slackMS;
+    uint32_t upperBoundMS = K*(periodMS + sleepPeriodMS) + slackMS;
+    if (logging) {
+      printf("Checking: %d-%d = %d [%d,%d]\n",
+             now, aObj->mLastUsed, timeDiffMS, lowerBoundMS, upperBoundMS);
+    }
+    if (timeDiffMS < lowerBoundMS || timeDiffMS > upperBoundMS) {
+      EXPECT_TRUE(timeDiffMS < periodMS && aObj->mExpired);
+    }
+    aObj->Touch();
+    aObj->mExpired = true;
+    DoRandomOperation();
+    DoRandomOperation();
+    DoRandomOperation();
+  }
+};
+
+template <uint32_t K> static bool test_random() {
+  srand(K);
+  error = false;
+ 
+  for (uint32_t j = 0; j < iterations; ++j) {
+    Tracker<K> tracker;
+
+    uint32_t i = 0;
+    for (i = 0; i < ops; ++i) {
+      if ((rand() & 0xF) == 0) {
+        // Simulate work that takes time
+        if (logging) {
+          printf("SLEEPING for %dms (%d)\n", sleepPeriodMS, PR_IntervalNow());
+        }
+        PR_Sleep(PR_MillisecondsToInterval(sleepPeriodMS));
+        // Process pending timer events
+        NS_ProcessPendingEvents(nullptr);
+      }
+      tracker.DoRandomOperation();
+    }
+  }
+  
+  return !error;
+}
+
+static bool test_random3() { return test_random<3>(); }
+static bool test_random4() { return test_random<4>(); }
+static bool test_random8() { return test_random<8>(); }
+
+typedef bool (*TestFunc)();
+#define DECL_TEST(name) { #name, name }
+
+static const struct Test {
+  const char* name;
+  TestFunc    func;
+} tests[] = {
+  DECL_TEST(test_random3),
+  DECL_TEST(test_random4),
+  DECL_TEST(test_random8),
+  { nullptr, nullptr }
+};
+
+TEST(ExpirationTracker, main)
+{
+  for (const TestExpirationTracker::Test* t = tests;
+       t->name != nullptr; ++t) {
+    EXPECT_TRUE(t->func());
+  }
+}
+
+} // namespace TestExpirationTracker
diff --git a/xpcom/tests/gtest/TestFile.cpp b/xpcom/tests/gtest/TestFile.cpp
new file mode 100644
index 000000000..7e7b4f4a1
--- /dev/null
+++ b/xpcom/tests/gtest/TestFile.cpp
@@ -0,0 +1,477 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "prio.h"
+#include "prsystem.h"
+
+#include "nsIFile.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsDirectoryServiceUtils.h"
+
+#include "gtest/gtest.h"
+
+static bool VerifyResult(nsresult aRV, const char* aMsg)
+{
+  bool failed = NS_FAILED(aRV);
+  EXPECT_FALSE(failed) << aMsg << " rv=" << std::hex << (unsigned int)aRV;
+  return !failed;
+}
+
+static already_AddRefed<nsIFile> NewFile(nsIFile* aBase)
+{
+  nsresult rv;
+  nsCOMPtr<nsIFile> file =
+    do_CreateInstance(NS_LOCAL_FILE_CONTRACTID, &rv);
+  VerifyResult(rv, "Creating nsIFile");
+  rv = file->InitWithFile(aBase);
+  VerifyResult(rv, "InitWithFile");
+  return file.forget();
+}
+
+static nsCString FixName(const char* aName)
+{
+  nsCString name;
+  for (uint32_t i = 0; aName[i]; ++i) {
+    char ch = aName[i];
+    // PR_GetPathSeparator returns the wrong value on Mac so don't use it
+#if defined(XP_WIN)
+    if (ch == '/') {
+      ch = '\\';
+    }
+#endif
+    name.Append(ch);
+  }
+  return name;
+}
+
+// Test nsIFile::AppendNative, verifying that aName is not a valid file name
+static bool TestInvalidFileName(nsIFile* aBase, const char* aName)
+{
+  nsCOMPtr<nsIFile> file = NewFile(aBase);
+  if (!file)
+    return false;
+
+  nsCString name = FixName(aName);
+  nsresult rv = file->AppendNative(name);
+  if (NS_SUCCEEDED(rv)) {
+    EXPECT_FALSE(NS_SUCCEEDED(rv)) << "AppendNative with invalid filename " << name.get();
+    return false;
+  }
+
+  return true;
+}
+
+// Test nsIFile::Create, verifying that the file exists and did not exist before,
+// and leaving it there for future tests
+static bool TestCreate(nsIFile* aBase, const char* aName, int32_t aType, int32_t aPerm)
+{
+  nsCOMPtr<nsIFile> file = NewFile(aBase);
+  if (!file)
+    return false;
+
+  nsCString name = FixName(aName);
+  nsresult rv = file->AppendNative(name);
+  if (!VerifyResult(rv, "AppendNative"))
+    return false;
+
+  bool exists;
+  rv = file->Exists(&exists);
+  if (!VerifyResult(rv, "Exists (before)"))
+    return false;
+  EXPECT_FALSE(exists) << "File "<< name.get() << " already exists";
+  if (exists) {
+    return false;
+  }
+
+  rv = file->Create(aType, aPerm);
+  if (!VerifyResult(rv, "Create"))
+    return false;
+
+  rv = file->Exists(&exists);
+  if (!VerifyResult(rv, "Exists (after)"))
+    return false;
+  EXPECT_TRUE(exists) << "File " << name.get() << " was not created";
+  if (!exists) {
+    return false;
+  }
+
+  return true;
+}
+
+// Test nsIFile::CreateUnique, verifying that the new file exists and if it existed before,
+// the new file has a different name.
+// The new file is left in place.
+static bool TestCreateUnique(nsIFile* aBase, const char* aName, int32_t aType, int32_t aPerm)
+{
+  nsCOMPtr<nsIFile> file = NewFile(aBase);
+  if (!file)
+    return false;
+
+  nsCString name = FixName(aName);
+  nsresult rv = file->AppendNative(name);
+  if (!VerifyResult(rv, "AppendNative"))
+    return false;
+
+  bool existsBefore;
+  rv = file->Exists(&existsBefore);
+  if (!VerifyResult(rv, "Exists (before)"))
+    return false;
+
+  rv = file->CreateUnique(aType, aPerm);
+  if (!VerifyResult(rv, "Create"))
+    return false;
+
+  bool existsAfter;
+  rv = file->Exists(&existsAfter);
+  if (!VerifyResult(rv, "Exists (after)"))
+    return false;
+  EXPECT_TRUE(existsAfter) << "File " << name.get() << " was not created";
+  if (!existsAfter) {
+    return false;
+  }
+
+  if (existsBefore) {
+    nsAutoCString leafName;
+    rv = file->GetNativeLeafName(leafName);
+    if (!VerifyResult(rv, "GetNativeLeafName"))
+      return false;
+    EXPECT_FALSE(leafName.Equals(name)) << "File " << name.get() << " was not given a new name by CreateUnique";
+    if (leafName.Equals(name)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+// Test nsIFile::OpenNSPRFileDesc with DELETE_ON_CLOSE, verifying that the file exists
+// and did not exist before, and leaving it there for future tests
+static bool TestDeleteOnClose(nsIFile* aBase, const char* aName, int32_t aFlags, int32_t aPerm)
+{
+  nsCOMPtr<nsIFile> file = NewFile(aBase);
+  if (!file)
+    return false;
+
+  nsCString name = FixName(aName);
+  nsresult rv = file->AppendNative(name);
+  if (!VerifyResult(rv, "AppendNative"))
+    return false;
+
+  bool exists;
+  rv = file->Exists(&exists);
+  if (!VerifyResult(rv, "Exists (before)"))
+    return false;
+  EXPECT_FALSE(exists) << "File " << name.get() << " already exists";
+  if (exists) {
+    return false;
+  }
+
+  PRFileDesc* fileDesc;
+  rv = file->OpenNSPRFileDesc(aFlags | nsIFile::DELETE_ON_CLOSE, aPerm, &fileDesc);
+  if (!VerifyResult(rv, "OpenNSPRFileDesc"))
+    return false;
+  PRStatus status = PR_Close(fileDesc);
+  EXPECT_EQ(status, PR_SUCCESS) << "File " << name.get() << " could not be closed";
+  if (status != PR_SUCCESS) {
+    return false;
+  }
+
+  rv = file->Exists(&exists);
+  if (!VerifyResult(rv, "Exists (after)"))
+    return false;
+  EXPECT_FALSE(exists) << "File " << name.get() << " was not removed on close";
+  if (exists) {
+    return false;
+  }
+
+  return true;
+}
+
+// Test nsIFile::Remove, verifying that the file does not exist and did before
+static bool TestRemove(nsIFile* aBase, const char* aName, bool aRecursive)
+{
+  nsCOMPtr<nsIFile> file = NewFile(aBase);
+  if (!file)
+    return false;
+
+  nsCString name = FixName(aName);
+  nsresult rv = file->AppendNative(name);
+  if (!VerifyResult(rv, "AppendNative"))
+    return false;
+
+  bool exists;
+  rv = file->Exists(&exists);
+  if (!VerifyResult(rv, "Exists (before)"))
+    return false;
+  EXPECT_TRUE(exists);
+  if (!exists) {
+    return false;
+  }
+
+  rv = file->Remove(aRecursive);
+  if (!VerifyResult(rv, "Remove"))
+    return false;
+
+  rv = file->Exists(&exists);
+  if (!VerifyResult(rv, "Exists (after)"))
+    return false;
+  EXPECT_FALSE(exists) << "File " << name.get() << " was not removed";
+  if (exists) {
+    return false;
+  }
+
+  return true;
+}
+
+// Test nsIFile::MoveToNative, verifying that the file did not exist at the new location
+// before and does afterward, and that it does not exist at the old location anymore
+static bool TestMove(nsIFile* aBase, nsIFile* aDestDir, const char* aName, const char* aNewName)
+{
+  nsCOMPtr<nsIFile> file = NewFile(aBase);
+  if (!file)
+    return false;
+
+  nsCString name = FixName(aName);
+  nsresult rv = file->AppendNative(name);
+  if (!VerifyResult(rv, "AppendNative"))
+    return false;
+
+  bool exists;
+  rv = file->Exists(&exists);
+  if (!VerifyResult(rv, "Exists (before)"))
+    return false;
+  EXPECT_TRUE(exists);
+  if (!exists) {
+    return false;
+  }
+
+  nsCOMPtr<nsIFile> newFile = NewFile(file);
+  nsCString newName = FixName(aNewName);
+  rv = newFile->MoveToNative(aDestDir, newName);
+  if (!VerifyResult(rv, "MoveToNative"))
+    return false;
+
+  rv = file->Exists(&exists);
+  if (!VerifyResult(rv, "Exists (after)"))
+    return false;
+  EXPECT_FALSE(exists) << "File " << name.get() << " was not moved";
+  if (exists) {
+    return false;
+  }
+
+  file = NewFile(aDestDir);
+  if (!file)
+    return false;
+  rv = file->AppendNative(newName);
+  if (!VerifyResult(rv, "AppendNative"))
+    return false;
+  bool equal;
+  rv = file->Equals(newFile, &equal);
+  if (!VerifyResult(rv, "Equals"))
+    return false;
+  EXPECT_TRUE(equal) << "File object was not updated to destination";
+  if (!equal) {
+    return false;
+  }
+
+  rv = file->Exists(&exists);
+  if (!VerifyResult(rv, "Exists (new after)"))
+    return false;
+  EXPECT_TRUE(exists) << "Destination file " << newName.get() << " was not created";
+  if (!exists) {
+    return false;
+  }
+
+  return true;
+}
+
+// Test nsIFile::CopyToNative, verifying that the file did not exist at the new location
+// before and does afterward, and that it does exist at the old location too
+static bool TestCopy(nsIFile* aBase, nsIFile* aDestDir, const char* aName, const char* aNewName)
+{
+  nsCOMPtr<nsIFile> file = NewFile(aBase);
+  if (!file)
+    return false;
+
+  nsCString name = FixName(aName);
+  nsresult rv = file->AppendNative(name);
+  if (!VerifyResult(rv, "AppendNative"))
+    return false;
+
+  bool exists;
+  rv = file->Exists(&exists);
+  if (!VerifyResult(rv, "Exists (before)"))
+    return false;
+  EXPECT_TRUE(exists);
+  if (!exists) {
+    return false;
+  }
+
+  nsCOMPtr<nsIFile> newFile = NewFile(file);
+  nsCString newName = FixName(aNewName);
+  rv = newFile->CopyToNative(aDestDir, newName);
+  if (!VerifyResult(rv, "MoveToNative"))
+    return false;
+  bool equal;
+  rv = file->Equals(newFile, &equal);
+  if (!VerifyResult(rv, "Equals"))
+    return false;
+  EXPECT_TRUE(equal) << "File object updated unexpectedly";
+  if (!equal) {
+    return false;
+  }
+
+  rv = file->Exists(&exists);
+  if (!VerifyResult(rv, "Exists (after)"))
+    return false;
+  EXPECT_TRUE(exists) << "File " << name.get() << " was removed";
+  if (!exists) {
+    return false;
+  }
+
+  file = NewFile(aDestDir);
+  if (!file)
+    return false;
+  rv = file->AppendNative(newName);
+  if (!VerifyResult(rv, "AppendNative"))
+    return false;
+
+  rv = file->Exists(&exists);
+  if (!VerifyResult(rv, "Exists (new after)"))
+    return false;
+  EXPECT_TRUE(exists) << "Destination file " << newName.get() << " was not created";
+  if (!exists) {
+    return false;
+  }
+
+  return true;
+}
+
+// Test nsIFile::GetParent
+static bool TestParent(nsIFile* aBase, nsIFile* aStart)
+{
+  nsCOMPtr<nsIFile> file = NewFile(aStart);
+  if (!file)
+    return false;
+
+  nsCOMPtr<nsIFile> parent;
+  nsresult rv = file->GetParent(getter_AddRefs(parent));
+  VerifyResult(rv, "GetParent");
+
+  bool equal;
+  rv = parent->Equals(aBase, &equal);
+  VerifyResult(rv, "Equals");
+  EXPECT_TRUE(equal) << "Incorrect parent";
+  if (!equal) {
+    return false;
+  }
+
+  return true;
+}
+
+// Test nsIFile::Normalize and native path setting/getting
+static bool TestNormalizeNativePath(nsIFile* aBase, nsIFile* aStart)
+{
+  nsCOMPtr<nsIFile> file = NewFile(aStart);
+  if (!file)
+    return false;
+
+  nsAutoCString path;
+  nsresult rv = file->GetNativePath(path);
+  VerifyResult(rv, "GetNativePath");
+  path.Append(FixName("/./.."));
+  rv = file->InitWithNativePath(path);
+  VerifyResult(rv, "InitWithNativePath");
+  rv = file->Normalize();
+  VerifyResult(rv, "Normalize");
+  rv = file->GetNativePath(path);
+  VerifyResult(rv, "GetNativePath (after normalization)");
+
+  nsAutoCString basePath;
+  rv = aBase->GetNativePath(basePath);
+  VerifyResult(rv, "GetNativePath (base)");
+
+  EXPECT_TRUE(path.Equals(basePath)) << "Incorrect normalization: " << path.get() << " - " << basePath.get();
+  if (!path.Equals(basePath)) {
+    return false;
+  }
+
+  return true;
+}
+
+TEST(TestFile, Tests)
+{
+  nsCOMPtr<nsIFile> base;
+  nsresult rv = NS_GetSpecialDirectory(NS_OS_TEMP_DIR, getter_AddRefs(base));
+  ASSERT_TRUE(VerifyResult(rv, "Getting temp directory"));
+
+  rv = base->AppendNative(nsDependentCString("mozfiletests"));
+  ASSERT_TRUE(VerifyResult(rv, "Appending mozfiletests to temp directory name"));
+
+  // Remove the directory in case tests failed and left it behind.
+  // don't check result since it might not be there
+  base->Remove(true);
+
+  // Now create the working directory we're going to use
+  rv = base->Create(nsIFile::DIRECTORY_TYPE, 0700);
+  ASSERT_TRUE(VerifyResult(rv, "Creating temp directory"));
+
+  // Now we can safely normalize the path
+  rv = base->Normalize();
+  ASSERT_TRUE(VerifyResult(rv, "Normalizing temp directory name"));
+
+  // Initialize subdir object for later use
+  nsCOMPtr<nsIFile> subdir = NewFile(base);
+  ASSERT_TRUE(subdir);
+
+  rv = subdir->AppendNative(nsDependentCString("subdir"));
+  ASSERT_TRUE(VerifyResult(rv, "Appending 'subdir' to test dir name"));
+
+  // ---------------
+  // End setup code.
+  // ---------------
+
+  // Test path parsing
+  ASSERT_TRUE(TestInvalidFileName(base, "a/b"));
+  ASSERT_TRUE(TestParent(base, subdir));
+
+  // Test file creation
+  ASSERT_TRUE(TestCreate(base, "file.txt", nsIFile::NORMAL_FILE_TYPE, 0600));
+  ASSERT_TRUE(TestRemove(base, "file.txt", false));
+
+  // Test directory creation
+  ASSERT_TRUE(TestCreate(base, "subdir", nsIFile::DIRECTORY_TYPE, 0700));
+
+  // Test move and copy in the base directory
+  ASSERT_TRUE(TestCreate(base, "file.txt", nsIFile::NORMAL_FILE_TYPE, 0600));
+  ASSERT_TRUE(TestMove(base, base, "file.txt", "file2.txt"));
+  ASSERT_TRUE(TestCopy(base, base, "file2.txt", "file3.txt"));
+
+  // Test moving across directories
+  ASSERT_TRUE(TestMove(base, subdir, "file2.txt", "file2.txt"));
+
+  // Test moving across directories and renaming at the same time
+  ASSERT_TRUE(TestMove(subdir, base, "file2.txt", "file4.txt"));
+
+  // Test copying across directoreis
+  ASSERT_TRUE(TestCopy(base, subdir, "file4.txt", "file5.txt"));
+
+  // Run normalization tests while the directory exists
+  ASSERT_TRUE(TestNormalizeNativePath(base, subdir));
+
+  // Test recursive directory removal
+  ASSERT_TRUE(TestRemove(base, "subdir", true));
+
+  ASSERT_TRUE(TestCreateUnique(base, "foo", nsIFile::NORMAL_FILE_TYPE, 0600));
+  ASSERT_TRUE(TestCreateUnique(base, "foo", nsIFile::NORMAL_FILE_TYPE, 0600));
+  ASSERT_TRUE(TestCreateUnique(base, "bar.xx", nsIFile::DIRECTORY_TYPE, 0700));
+  ASSERT_TRUE(TestCreateUnique(base, "bar.xx", nsIFile::DIRECTORY_TYPE, 0700));
+
+  ASSERT_TRUE(TestDeleteOnClose(base, "file7.txt", PR_RDWR | PR_CREATE_FILE, 0600));
+
+  // Clean up temporary stuff
+  rv = base->Remove(true);
+  VerifyResult(rv, "Cleaning up temp directory");
+}
diff --git a/xpcom/tests/gtest/TestHashtables.cpp b/xpcom/tests/gtest/TestHashtables.cpp
new file mode 100644
index 000000000..394812631
--- /dev/null
+++ b/xpcom/tests/gtest/TestHashtables.cpp
@@ -0,0 +1,435 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsTHashtable.h"
+#include "nsBaseHashtable.h"
+#include "nsDataHashtable.h"
+#include "nsInterfaceHashtable.h"
+#include "nsClassHashtable.h"
+
+#include "nsCOMPtr.h"
+#include "nsISupports.h"
+#include "nsCOMArray.h"
+#include "mozilla/Attributes.h"
+
+#include "gtest/gtest.h"
+
+namespace TestHashtables {
+
+class TestUniChar // for nsClassHashtable
+{
+public:
+  explicit TestUniChar(uint32_t aWord)
+  {
+    mWord = aWord;
+  }
+
+  ~TestUniChar()
+  {
+  }
+
+  uint32_t GetChar() const { return mWord; }
+
+private:
+  uint32_t mWord;
+};
+
+struct EntityNode {
+  const char*   mStr; // never owns buffer
+  uint32_t       mUnicode;
+};
+
+EntityNode gEntities[] = {
+  {"nbsp",160},
+  {"iexcl",161},
+  {"cent",162},
+  {"pound",163},
+  {"curren",164},
+  {"yen",165},
+  {"brvbar",166},
+  {"sect",167},
+  {"uml",168},
+  {"copy",169},
+  {"ordf",170},
+  {"laquo",171},
+  {"not",172},
+  {"shy",173},
+  {"reg",174},
+  {"macr",175}
+};
+
+#define ENTITY_COUNT (unsigned(sizeof(gEntities)/sizeof(EntityNode)))
+
+class EntityToUnicodeEntry : public PLDHashEntryHdr
+{
+public:
+  typedef const char* KeyType;
+  typedef const char* KeyTypePointer;
+
+  explicit EntityToUnicodeEntry(const char* aKey) { mNode = nullptr; }
+  EntityToUnicodeEntry(const EntityToUnicodeEntry& aEntry) { mNode = aEntry.mNode; }
+  ~EntityToUnicodeEntry() { }
+
+  bool KeyEquals(const char* aEntity) const { return !strcmp(mNode->mStr, aEntity); }
+  static const char* KeyToPointer(const char* aEntity) { return aEntity; }
+  static PLDHashNumber HashKey(const char* aEntity) { return mozilla::HashString(aEntity); }
+  enum { ALLOW_MEMMOVE = true };
+
+  const EntityNode* mNode;
+};
+
+static uint32_t
+nsTIterPrint(nsTHashtable<EntityToUnicodeEntry>& hash)
+{
+  uint32_t n = 0;
+  for (auto iter = hash.Iter(); !iter.Done(); iter.Next()) {
+    n++;
+  }
+  return n;
+}
+
+static uint32_t
+nsTIterPrintRemove(nsTHashtable<EntityToUnicodeEntry>& hash)
+{
+  uint32_t n = 0;
+  for (auto iter = hash.Iter(); !iter.Done(); iter.Next()) {
+    iter.Remove();
+    n++;
+  }
+  return n;
+}
+
+void
+testTHashtable(nsTHashtable<EntityToUnicodeEntry>& hash, uint32_t numEntries) {
+  uint32_t i;
+  for (i = 0; i < numEntries; ++i) {
+    EntityToUnicodeEntry* entry =
+      hash.PutEntry(gEntities[i].mStr);
+
+    EXPECT_TRUE(entry);
+
+    EXPECT_FALSE(entry->mNode);
+    entry->mNode = &gEntities[i];
+  }
+
+  for (i = 0; i < numEntries; ++i) {
+    EntityToUnicodeEntry* entry =
+      hash.GetEntry(gEntities[i].mStr);
+
+    EXPECT_TRUE(entry);
+  }
+
+  EntityToUnicodeEntry* entry =
+    hash.GetEntry("xxxy");
+
+  EXPECT_FALSE(entry);
+
+  uint32_t count = nsTIterPrint(hash);
+  EXPECT_EQ(count, numEntries);
+}
+
+//
+// all this nsIFoo stuff was copied wholesale from TestCOMPtr.cpp
+//
+
+#define NS_IFOO_IID \
+{ 0x6f7652e0,  0xee43, 0x11d1, \
+ { 0x9c, 0xc3, 0x00, 0x60, 0x08, 0x8c, 0xa6, 0xb3 } }
+
+class IFoo final : public nsISupports
+  {
+    public:
+      NS_DECLARE_STATIC_IID_ACCESSOR(NS_IFOO_IID)
+
+      IFoo();
+
+      NS_IMETHOD_(MozExternalRefCountType) AddRef();
+      NS_IMETHOD_(MozExternalRefCountType) Release();
+      NS_IMETHOD QueryInterface( const nsIID&, void** );
+
+      NS_IMETHOD SetString(const nsACString& /*in*/ aString);
+      NS_IMETHOD GetString(nsACString& /*out*/ aString);
+
+      static void print_totals();
+
+    private:
+      ~IFoo();
+
+      unsigned int refcount_;
+
+      static unsigned int total_constructions_;
+      static unsigned int total_destructions_;
+      nsCString mString;
+  };
+
+NS_DEFINE_STATIC_IID_ACCESSOR(IFoo, NS_IFOO_IID)
+
+unsigned int IFoo::total_constructions_;
+unsigned int IFoo::total_destructions_;
+
+void
+IFoo::print_totals()
+  {
+  }
+
+IFoo::IFoo()
+    : refcount_(0)
+  {
+    ++total_constructions_;
+  }
+
+IFoo::~IFoo()
+  {
+    ++total_destructions_;
+  }
+
+MozExternalRefCountType
+IFoo::AddRef()
+  {
+    ++refcount_;
+    return refcount_;
+  }
+
+MozExternalRefCountType
+IFoo::Release()
+  {
+    int newcount = --refcount_;
+    if ( newcount == 0 )
+      {
+        delete this;
+      }
+
+    return newcount;
+  }
+
+nsresult
+IFoo::QueryInterface( const nsIID& aIID, void** aResult )
+  {
+    nsISupports* rawPtr = 0;
+    nsresult status = NS_OK;
+
+    if ( aIID.Equals(NS_GET_IID(IFoo)) )
+      rawPtr = this;
+    else
+      {
+        nsID iid_of_ISupports = NS_ISUPPORTS_IID;
+        if ( aIID.Equals(iid_of_ISupports) )
+          rawPtr = static_cast<nsISupports*>(this);
+        else
+          status = NS_ERROR_NO_INTERFACE;
+      }
+
+    NS_IF_ADDREF(rawPtr);
+    *aResult = rawPtr;
+
+    return status;
+  }
+
+nsresult
+IFoo::SetString(const nsACString& aString)
+{
+  mString = aString;
+  return NS_OK;
+}
+
+nsresult
+IFoo::GetString(nsACString& aString)
+{
+  aString = mString;
+  return NS_OK;
+}
+
+nsresult
+CreateIFoo( IFoo** result )
+    // a typical factory function (that calls AddRef)
+  {
+    IFoo* foop = new IFoo();
+
+    foop->AddRef();
+    *result = foop;
+
+    return NS_OK;
+  }
+
+} // namespace TestHashtables
+
+using namespace TestHashtables;
+
+TEST(Hashtable, THashtable)
+{
+  // check an nsTHashtable
+  nsTHashtable<EntityToUnicodeEntry> EntityToUnicode(ENTITY_COUNT);
+
+  testTHashtable(EntityToUnicode, 5);
+
+  uint32_t count = nsTIterPrintRemove(EntityToUnicode);
+  ASSERT_EQ(count, uint32_t(5));
+
+  count = nsTIterPrint(EntityToUnicode);
+  ASSERT_EQ(count, uint32_t(0));
+
+  testTHashtable(EntityToUnicode, ENTITY_COUNT);
+
+  EntityToUnicode.Clear();
+
+  count = nsTIterPrint(EntityToUnicode);
+  ASSERT_EQ(count, uint32_t(0));
+}
+
+TEST(Hashtables, DataHashtable)
+{
+  // check a data-hashtable
+  nsDataHashtable<nsUint32HashKey,const char*> UniToEntity(ENTITY_COUNT);
+
+  for (uint32_t i = 0; i < ENTITY_COUNT; ++i) {
+    UniToEntity.Put(gEntities[i].mUnicode, gEntities[i].mStr);
+  }
+
+  const char* str;
+
+  for (uint32_t i = 0; i < ENTITY_COUNT; ++i) {
+    ASSERT_TRUE(UniToEntity.Get(gEntities[i].mUnicode, &str));
+  }
+
+  ASSERT_FALSE(UniToEntity.Get(99446, &str));
+
+  uint32_t count = 0;
+  for (auto iter = UniToEntity.Iter(); !iter.Done(); iter.Next()) {
+    count++;
+  }
+  ASSERT_EQ(count, ENTITY_COUNT);
+
+  UniToEntity.Clear();
+
+  count = 0;
+  for (auto iter = UniToEntity.Iter(); !iter.Done(); iter.Next()) {
+    printf("  enumerated %u = \"%s\"\n", iter.Key(), iter.Data());
+    count++;
+  }
+  ASSERT_EQ(count, uint32_t(0));
+}
+
+TEST(Hashtables, ClassHashtable)
+{
+  // check a class-hashtable
+  nsClassHashtable<nsCStringHashKey,TestUniChar> EntToUniClass(ENTITY_COUNT);
+
+  for (uint32_t i = 0; i < ENTITY_COUNT; ++i) {
+    TestUniChar* temp = new TestUniChar(gEntities[i].mUnicode);
+    EntToUniClass.Put(nsDependentCString(gEntities[i].mStr), temp);
+  }
+
+  TestUniChar* myChar;
+
+  for (uint32_t i = 0; i < ENTITY_COUNT; ++i) {
+    ASSERT_TRUE(EntToUniClass.Get(nsDependentCString(gEntities[i].mStr), &myChar));
+  }
+
+  ASSERT_FALSE(EntToUniClass.Get(NS_LITERAL_CSTRING("xxxx"), &myChar));
+
+  uint32_t count = 0;
+  for (auto iter = EntToUniClass.Iter(); !iter.Done(); iter.Next()) {
+    count++;
+  }
+  ASSERT_EQ(count, ENTITY_COUNT);
+
+  EntToUniClass.Clear();
+
+  count = 0;
+  for (auto iter = EntToUniClass.Iter(); !iter.Done(); iter.Next()) {
+    count++;
+  }
+  ASSERT_EQ(count, uint32_t(0));
+}
+
+TEST(Hashtables, DataHashtableWithInterfaceKey)
+{
+  // check a data-hashtable with an interface key
+  nsDataHashtable<nsISupportsHashKey,uint32_t> EntToUniClass2(ENTITY_COUNT);
+
+  nsCOMArray<IFoo> fooArray;
+
+  for (uint32_t i = 0; i < ENTITY_COUNT; ++i) {
+    nsCOMPtr<IFoo> foo;
+    CreateIFoo(getter_AddRefs(foo));
+    foo->SetString(nsDependentCString(gEntities[i].mStr));
+
+    fooArray.InsertObjectAt(foo, i);
+
+    EntToUniClass2.Put(foo, gEntities[i].mUnicode);
+  }
+
+  uint32_t myChar2;
+
+  for (uint32_t i = 0; i < ENTITY_COUNT; ++i) {
+    ASSERT_TRUE(EntToUniClass2.Get(fooArray[i], &myChar2));
+  }
+
+  ASSERT_FALSE(EntToUniClass2.Get((nsISupports*) 0x55443316, &myChar2));
+
+  uint32_t count = 0;
+  for (auto iter = EntToUniClass2.Iter(); !iter.Done(); iter.Next()) {
+    nsAutoCString s;
+    nsCOMPtr<IFoo> foo = do_QueryInterface(iter.Key());
+    foo->GetString(s);
+    count++;
+  }
+  ASSERT_EQ(count, ENTITY_COUNT);
+
+  EntToUniClass2.Clear();
+
+  count = 0;
+  for (auto iter = EntToUniClass2.Iter(); !iter.Done(); iter.Next()) {
+    nsAutoCString s;
+    nsCOMPtr<IFoo> foo = do_QueryInterface(iter.Key());
+    foo->GetString(s);
+    count++;
+  }
+  ASSERT_EQ(count, uint32_t(0));
+}
+
+TEST(Hashtables, InterfaceHashtable)
+{
+  // check an interface-hashtable with an uint32_t key
+  nsInterfaceHashtable<nsUint32HashKey,IFoo> UniToEntClass2(ENTITY_COUNT);
+
+  for (uint32_t i = 0; i < ENTITY_COUNT; ++i) {
+    nsCOMPtr<IFoo> foo;
+    CreateIFoo(getter_AddRefs(foo));
+    foo->SetString(nsDependentCString(gEntities[i].mStr));
+
+    UniToEntClass2.Put(gEntities[i].mUnicode, foo);
+  }
+
+  for (uint32_t i = 0; i < ENTITY_COUNT; ++i) {
+    nsCOMPtr<IFoo> myEnt;
+    ASSERT_TRUE(UniToEntClass2.Get(gEntities[i].mUnicode, getter_AddRefs(myEnt)));
+
+    nsAutoCString myEntStr;
+    myEnt->GetString(myEntStr);
+  }
+
+  nsCOMPtr<IFoo> myEnt;
+  ASSERT_FALSE(UniToEntClass2.Get(9462, getter_AddRefs(myEnt)));
+
+  uint32_t count = 0;
+  for (auto iter = UniToEntClass2.Iter(); !iter.Done(); iter.Next()) {
+    nsAutoCString s;
+    iter.UserData()->GetString(s);
+    count++;
+  }
+  ASSERT_EQ(count, ENTITY_COUNT);
+
+  UniToEntClass2.Clear();
+
+  count = 0;
+  for (auto iter = UniToEntClass2.Iter(); !iter.Done(); iter.Next()) {
+    nsAutoCString s;
+    iter.Data()->GetString(s);
+    count++;
+  }
+  ASSERT_EQ(count, uint32_t(0));
+}
diff --git a/xpcom/tests/gtest/TestID.cpp b/xpcom/tests/gtest/TestID.cpp
new file mode 100644
index 000000000..cb56554dc
--- /dev/null
+++ b/xpcom/tests/gtest/TestID.cpp
@@ -0,0 +1,36 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsID.h"
+
+#include "gtest/gtest.h"
+
+static const char* const ids[] = {
+  "5C347B10-D55C-11D1-89B7-006008911B81",
+  "{5C347B10-D55C-11D1-89B7-006008911B81}",
+  "5c347b10-d55c-11d1-89b7-006008911b81",
+  "{5c347b10-d55c-11d1-89b7-006008911b81}",
+
+  "FC347B10-D55C-F1D1-F9B7-006008911B81",
+  "{FC347B10-D55C-F1D1-F9B7-006008911B81}",
+  "fc347b10-d55c-f1d1-f9b7-006008911b81",
+  "{fc347b10-d55c-f1d1-f9b7-006008911b81}",
+};
+#define NUM_IDS ((int) (sizeof(ids) / sizeof(ids[0])))
+
+TEST(nsID, StringConversion)
+{
+  nsID id;
+  for (int i = 0; i < NUM_IDS; i++) {
+    const char* idstr = ids[i];
+    ASSERT_TRUE(id.Parse(idstr));
+
+    char* cp = id.ToString();
+    ASSERT_NE(cp, nullptr);
+    ASSERT_STREQ(cp, ids[4*(i/4) + 3]);
+
+    free(cp);
+  }
+}
diff --git a/xpcom/tests/gtest/TestNSPRLogModulesParser.cpp b/xpcom/tests/gtest/TestNSPRLogModulesParser.cpp
new file mode 100644
index 000000000..4fd924175
--- /dev/null
+++ b/xpcom/tests/gtest/TestNSPRLogModulesParser.cpp
@@ -0,0 +1,111 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "NSPRLogModulesParser.h"
+#include "mozilla/ArrayUtils.h"
+#include "gtest/gtest.h"
+
+using namespace mozilla;
+
+TEST(NSPRLogModulesParser, Empty)
+{
+  bool callbackInvoked = false;
+  auto callback = [&](const char*, mozilla::LogLevel, int32_t) mutable { callbackInvoked = true; };
+
+  mozilla::NSPRLogModulesParser(nullptr, callback);
+  EXPECT_FALSE(callbackInvoked);
+
+  mozilla::NSPRLogModulesParser("", callback);
+  EXPECT_FALSE(callbackInvoked);
+}
+
+TEST(NSPRLogModulesParser, DefaultLevel)
+{
+  bool callbackInvoked = false;
+  auto callback =
+      [&](const char* aName, mozilla::LogLevel aLevel, int32_t) {
+        EXPECT_STREQ("Foo", aName);
+        EXPECT_EQ(mozilla::LogLevel::Error, aLevel);
+        callbackInvoked = true;
+      };
+
+  mozilla::NSPRLogModulesParser("Foo", callback);
+  EXPECT_TRUE(callbackInvoked);
+
+  callbackInvoked = false;
+  mozilla::NSPRLogModulesParser("Foo:", callback);
+  EXPECT_TRUE(callbackInvoked);
+}
+
+TEST(NSPRLogModulesParser, LevelSpecified)
+{
+  std::pair<const char*, mozilla::LogLevel> expected[] = {
+    { "Foo:0", mozilla::LogLevel::Disabled },
+    { "Foo:1", mozilla::LogLevel::Error },
+    { "Foo:2", mozilla::LogLevel::Warning },
+    { "Foo:3", mozilla::LogLevel::Info },
+    { "Foo:4", mozilla::LogLevel::Debug },
+    { "Foo:5", mozilla::LogLevel::Verbose },
+    { "Foo:25", mozilla::LogLevel::Verbose },  // too high
+    { "Foo:-12", mozilla::LogLevel::Disabled } // too low
+  };
+
+  auto* currTest = expected;
+
+  for (size_t i = 0; i < MOZ_ARRAY_LENGTH(expected); i++) {
+    bool callbackInvoked = false;
+    mozilla::NSPRLogModulesParser(currTest->first,
+        [&](const char* aName, mozilla::LogLevel aLevel, int32_t) {
+          EXPECT_STREQ("Foo", aName);
+          EXPECT_EQ(currTest->second, aLevel);
+          callbackInvoked = true;
+        });
+    EXPECT_TRUE(callbackInvoked);
+    currTest++;
+  }
+}
+
+TEST(NSPRLogModulesParser, Multiple)
+{
+  std::pair<const char*, mozilla::LogLevel> expected[] = {
+    { "timestamp", mozilla::LogLevel::Error },
+    { "Foo", mozilla::LogLevel::Info },
+    { "Bar", mozilla::LogLevel::Error },
+    { "Baz", mozilla::LogLevel::Warning },
+    { "Qux", mozilla::LogLevel::Verbose },
+  };
+
+  const size_t kExpectedCount = MOZ_ARRAY_LENGTH(expected);
+
+  auto* currTest = expected;
+
+  size_t count = 0;
+  mozilla::NSPRLogModulesParser("timestamp,Foo:3, Bar,Baz:2,    Qux:5",
+      [&](const char* aName, mozilla::LogLevel aLevel, int32_t) mutable {
+        ASSERT_LT(count, kExpectedCount);
+        EXPECT_STREQ(currTest->first, aName);
+        EXPECT_EQ(currTest->second, aLevel);
+        currTest++;
+        count++;
+     });
+
+  EXPECT_EQ(kExpectedCount, count);
+}
+
+TEST(NSPRLogModulesParser, RawArg)
+{
+  bool callbackInvoked = false;
+  auto callback =
+    [&](const char* aName, mozilla::LogLevel aLevel, int32_t aRawValue) {
+    EXPECT_STREQ("Foo", aName);
+    EXPECT_EQ(mozilla::LogLevel::Verbose, aLevel);
+    EXPECT_EQ(1000, aRawValue);
+    callbackInvoked = true;
+  };
+
+  mozilla::NSPRLogModulesParser("Foo:1000", callback);
+  EXPECT_TRUE(callbackInvoked);
+}
diff --git a/xpcom/tests/gtest/TestNsRefPtr.cpp b/xpcom/tests/gtest/TestNsRefPtr.cpp
new file mode 100644
index 000000000..a085c2966
--- /dev/null
+++ b/xpcom/tests/gtest/TestNsRefPtr.cpp
@@ -0,0 +1,479 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/RefPtr.h"
+#include "nsCOMPtr.h"
+#include "nsISupports.h"
+#include "nsQueryObject.h"
+#include "mozilla/Unused.h"
+
+#include "gtest/gtest.h"
+
+namespace TestNsRefPtr
+{
+
+#define NS_FOO_IID \
+{ 0x6f7652e0,  0xee43, 0x11d1, \
+  { 0x9c, 0xc3, 0x00, 0x60, 0x08, 0x8c, 0xa6, 0xb3 } }
+
+class Foo : public nsISupports
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_FOO_IID)
+
+public:
+  Foo();
+  // virtual dtor because Bar uses our Release()
+  virtual ~Foo();
+
+  NS_IMETHOD_(MozExternalRefCountType) AddRef();
+  NS_IMETHOD_(MozExternalRefCountType) Release();
+  NS_IMETHOD QueryInterface( const nsIID&, void** );
+  void MemberFunction( int, int*, int& );
+  virtual void VirtualMemberFunction( int, int*, int& );
+  virtual void VirtualConstMemberFunction( int, int*, int& ) const;
+
+  void NonconstMethod() {}
+  void ConstMethod() const {}
+
+  int refcount_;
+
+  static int total_constructions_;
+  static int total_destructions_;
+  static int total_addrefs_;
+  static int total_queries_;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(Foo, NS_FOO_IID)
+
+int Foo::total_constructions_;
+int Foo::total_destructions_;
+int Foo::total_addrefs_;
+int Foo::total_queries_;
+
+Foo::Foo()
+  : refcount_(0)
+{
+  ++total_constructions_;
+}
+
+Foo::~Foo()
+{
+  ++total_destructions_;
+}
+
+MozExternalRefCountType
+Foo::AddRef()
+{
+  ++refcount_;
+  ++total_addrefs_;
+  return refcount_;
+}
+
+MozExternalRefCountType
+Foo::Release()
+{
+  int newcount = --refcount_;
+  if ( newcount == 0 )
+  {
+    delete this;
+  }
+
+  return newcount;
+}
+
+nsresult
+Foo::QueryInterface( const nsIID& aIID, void** aResult )
+{
+  ++total_queries_;
+
+  nsISupports* rawPtr = 0;
+  nsresult status = NS_OK;
+
+  if ( aIID.Equals(NS_GET_IID(Foo)) )
+    rawPtr = this;
+  else
+  {
+    nsID iid_of_ISupports = NS_ISUPPORTS_IID;
+    if ( aIID.Equals(iid_of_ISupports) )
+      rawPtr = static_cast<nsISupports*>(this);
+    else
+      status = NS_ERROR_NO_INTERFACE;
+  }
+
+  NS_IF_ADDREF(rawPtr);
+  *aResult = rawPtr;
+
+  return status;
+}
+
+void
+Foo::MemberFunction( int aArg1, int* aArgPtr, int& aArgRef )
+{
+}
+
+void
+Foo::VirtualMemberFunction( int aArg1, int* aArgPtr, int& aArgRef )
+{
+}
+
+void
+Foo::VirtualConstMemberFunction( int aArg1, int* aArgPtr, int& aArgRef ) const
+{
+}
+
+nsresult
+CreateFoo( void** result )
+  // a typical factory function (that calls AddRef)
+{
+  Foo* foop = new Foo;
+
+  foop->AddRef();
+  *result = foop;
+
+  return NS_OK;
+}
+
+void
+set_a_Foo( RefPtr<Foo>* result )
+{
+  assert(result);
+
+  RefPtr<Foo> foop( do_QueryObject(new Foo) );
+  *result = foop;
+}
+
+RefPtr<Foo>
+return_a_Foo()
+{
+  RefPtr<Foo> foop( do_QueryObject(new Foo) );
+  return foop;
+}
+
+#define NS_BAR_IID \
+{ 0x6f7652e1,  0xee43, 0x11d1, \
+  { 0x9c, 0xc3, 0x00, 0x60, 0x08, 0x8c, 0xa6, 0xb3 } }
+
+class Bar : public Foo
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_BAR_IID)
+
+public:
+  Bar();
+  virtual ~Bar();
+
+  NS_IMETHOD QueryInterface( const nsIID&, void** ) override;
+
+  virtual void VirtualMemberFunction( int, int*, int& ) override;
+  virtual void VirtualConstMemberFunction( int, int*, int& ) const override;
+
+  static int total_constructions_;
+  static int total_destructions_;
+  static int total_queries_;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(Bar, NS_BAR_IID)
+
+int Bar::total_constructions_;
+int Bar::total_destructions_;
+int Bar::total_queries_;
+
+Bar::Bar()
+{
+  ++total_constructions_;
+}
+
+Bar::~Bar()
+{
+  ++total_destructions_;
+}
+
+nsresult
+Bar::QueryInterface( const nsID& aIID, void** aResult )
+{
+  ++total_queries_;
+
+  nsISupports* rawPtr = 0;
+  nsresult status = NS_OK;
+
+  if ( aIID.Equals(NS_GET_IID(Bar)) )
+    rawPtr = this;
+  else if ( aIID.Equals(NS_GET_IID(Foo)) )
+    rawPtr = static_cast<Foo*>(this);
+  else
+  {
+    nsID iid_of_ISupports = NS_ISUPPORTS_IID;
+    if ( aIID.Equals(iid_of_ISupports) )
+      rawPtr = static_cast<nsISupports*>(this);
+    else
+      status = NS_ERROR_NO_INTERFACE;
+  }
+
+  NS_IF_ADDREF(rawPtr);
+  *aResult = rawPtr;
+
+  return status;
+}
+
+void
+Bar::VirtualMemberFunction( int aArg1, int* aArgPtr, int& aArgRef )
+{
+}
+void
+Bar::VirtualConstMemberFunction( int aArg1, int* aArgPtr, int& aArgRef ) const
+{
+}
+
+} // namespace TestNsRefPtr
+
+using namespace TestNsRefPtr;
+
+TEST(nsRefPtr, AddRefAndRelease)
+{
+  Foo::total_constructions_ = 0;
+  Foo::total_destructions_ = 0;
+
+  {
+    RefPtr<Foo> foop( do_QueryObject(new Foo) );
+    ASSERT_EQ(Foo::total_constructions_, 1);
+    ASSERT_EQ(Foo::total_destructions_, 0);
+    ASSERT_EQ(foop->refcount_, 1);
+
+    foop = do_QueryObject(new Foo);
+    ASSERT_EQ(Foo::total_constructions_, 2);
+    ASSERT_EQ(Foo::total_destructions_, 1);
+
+    // [Shouldn't compile] Is it a compile time error to try to |AddRef| by hand?
+    //foop->AddRef();
+
+    // [Shouldn't compile] Is it a compile time error to try to |Release| be hand?
+    //foop->Release();
+
+    // [Shouldn't compile] Is it a compile time error to try to |delete| an |nsCOMPtr|?
+    //delete foop;
+
+    static_cast<Foo*>(foop)->AddRef();
+    ASSERT_EQ(foop->refcount_, 2);
+
+    static_cast<Foo*>(foop)->Release();
+    ASSERT_EQ(foop->refcount_, 1);
+  }
+
+  ASSERT_EQ(Foo::total_destructions_, 2);
+
+  {
+    RefPtr<Foo> fooP( do_QueryObject(new Foo) );
+    ASSERT_EQ(Foo::total_constructions_, 3);
+    ASSERT_EQ(Foo::total_destructions_, 2);
+    ASSERT_EQ(fooP->refcount_, 1);
+
+    Foo::total_addrefs_ = 0;
+    RefPtr<Foo> fooP2( fooP.forget() );
+    ASSERT_EQ(Foo::total_addrefs_, 0);
+  }
+}
+
+TEST(nsRefPtr, VirtualDestructor)
+{
+  Bar::total_destructions_ = 0;
+
+  {
+    RefPtr<Foo> foop( do_QueryObject(new Bar) );
+    mozilla::Unused << foop;
+  }
+
+  ASSERT_EQ(Bar::total_destructions_, 1);
+}
+
+TEST(nsRefPtr, Equality)
+{
+  Foo::total_constructions_ = 0;
+  Foo::total_destructions_ = 0;
+
+  {
+    RefPtr<Foo> foo1p( do_QueryObject(new Foo) );
+    RefPtr<Foo> foo2p( do_QueryObject(new Foo) );
+
+    ASSERT_EQ(Foo::total_constructions_, 2);
+    ASSERT_EQ(Foo::total_destructions_, 0);
+
+    ASSERT_NE(foo1p, foo2p);
+
+    ASSERT_NE(foo1p, nullptr);
+    ASSERT_NE(nullptr, foo1p);
+    ASSERT_FALSE(foo1p == nullptr);
+    ASSERT_FALSE(nullptr == foo1p);
+
+    ASSERT_NE(foo1p, foo2p.get());
+
+    foo1p = foo2p;
+
+    ASSERT_EQ(Foo::total_constructions_, 2);
+    ASSERT_EQ(Foo::total_destructions_, 1);
+    ASSERT_EQ(foo1p, foo2p);
+
+    ASSERT_EQ(foo2p, foo2p.get());
+
+    ASSERT_EQ(RefPtr<Foo>(foo2p.get()), foo2p);
+
+    ASSERT_TRUE(foo1p);
+  }
+
+  ASSERT_EQ(Foo::total_constructions_, 2);
+  ASSERT_EQ(Foo::total_destructions_, 2);
+}
+
+TEST(nsRefPtr, AddRefHelpers)
+{
+  Foo::total_addrefs_ = 0;
+
+  {
+    Foo* raw_foo1p = new Foo;
+    raw_foo1p->AddRef();
+
+    Foo* raw_foo2p = new Foo;
+    raw_foo2p->AddRef();
+
+    ASSERT_EQ(Foo::total_addrefs_, 2);
+
+    RefPtr<Foo> foo1p( dont_AddRef(raw_foo1p) );
+
+    ASSERT_EQ(Foo::total_addrefs_, 2);
+
+    RefPtr<Foo> foo2p;
+    foo2p = dont_AddRef(raw_foo2p);
+
+    ASSERT_EQ(Foo::total_addrefs_, 2);
+  }
+
+  {
+    // Test that various assignment helpers compile.
+    RefPtr<Foo> foop;
+    CreateFoo( RefPtrGetterAddRefs<Foo>(foop) );
+    CreateFoo( getter_AddRefs(foop) );
+    set_a_Foo(address_of(foop));
+    foop = return_a_Foo();
+  }
+}
+
+TEST(nsRefPtr, QueryInterface)
+{
+  Foo::total_queries_ = 0;
+  Bar::total_queries_ = 0;
+
+  {
+    RefPtr<Foo> fooP;
+    fooP = do_QueryObject(new Foo);
+    ASSERT_EQ(Foo::total_queries_, 1);
+  }
+
+  {
+    RefPtr<Foo> fooP;
+    fooP = do_QueryObject(new Foo);
+    ASSERT_EQ(Foo::total_queries_, 2);
+
+    RefPtr<Foo> foo2P;
+    foo2P = fooP;
+    ASSERT_EQ(Foo::total_queries_, 2);
+  }
+
+  {
+    RefPtr<Bar> barP( do_QueryObject(new Bar) );
+    ASSERT_EQ(Bar::total_queries_, 1);
+
+    RefPtr<Foo> fooP( do_QueryObject(barP) );
+    ASSERT_TRUE(fooP);
+    ASSERT_EQ(Foo::total_queries_, 2);
+    ASSERT_EQ(Bar::total_queries_, 2);
+  }
+}
+
+// -------------------------------------------------------------------------
+// TODO(ER): The following tests should be moved to MFBT.
+
+#define NS_INLINE_DECL_THREADSAFE_MUTABLE_REFCOUNTING(_class)               \
+public:                                                                     \
+NS_METHOD_(MozExternalRefCountType) AddRef(void) const {                    \
+  MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                                \
+  MOZ_RELEASE_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");              \
+  nsrefcnt count = ++mRefCnt;                                               \
+  return (nsrefcnt) count;                                                  \
+}                                                                           \
+NS_METHOD_(MozExternalRefCountType) Release(void) const {                   \
+  MOZ_RELEASE_ASSERT(int32_t(mRefCnt) > 0, "dup release");                  \
+  nsrefcnt count = --mRefCnt;                                               \
+  if (count == 0) {                                                         \
+    delete (this);                                                          \
+    return 0;                                                               \
+  }                                                                         \
+  return count;                                                             \
+}                                                                           \
+protected:                                                                  \
+mutable ::mozilla::ThreadSafeAutoRefCnt mRefCnt;                            \
+public:
+
+class ObjectForConstPtr
+{
+  private:
+    // Reference-counted classes cannot have public destructors.
+    ~ObjectForConstPtr()
+    {
+    }
+  public:
+    NS_INLINE_DECL_THREADSAFE_MUTABLE_REFCOUNTING(ObjectForConstPtr)
+      void ConstMemberFunction( int aArg1, int* aArgPtr, int& aArgRef ) const
+      {
+      }
+};
+#undef NS_INLINE_DECL_THREADSAFE_MUTABLE_REFCOUNTING
+
+namespace TestNsRefPtr
+{
+void AnFooPtrPtrContext(Foo**) { }
+void AVoidPtrPtrContext(void**) { }
+} // namespace TestNsRefPtr
+
+TEST(nsRefPtr, RefPtrCompilationTests)
+{
+
+  {
+    RefPtr<Foo> fooP;
+
+    AnFooPtrPtrContext( getter_AddRefs(fooP) );
+    AVoidPtrPtrContext( getter_AddRefs(fooP) );
+  }
+
+  {
+    RefPtr<Foo> fooP(new Foo);
+    RefPtr<const Foo> constFooP = fooP;
+    constFooP->ConstMethod();
+
+    // [Shouldn't compile] Is it a compile time error to call a non-const method on an |RefPtr<const T>|?
+    //constFooP->NonconstMethod();
+
+    // [Shouldn't compile] Is it a compile time error to construct an |RefPtr<T> from an |RefPtr<const T>|?
+    //RefPtr<Foo> otherFooP(constFooP);
+  }
+
+  {
+    RefPtr<Foo> foop = new Foo;
+    RefPtr<Foo> foop2 = new Bar;
+    RefPtr<const ObjectForConstPtr> foop3 = new ObjectForConstPtr;
+    int test = 1;
+    void (Foo::*fPtr)( int, int*, int& ) = &Foo::MemberFunction;
+    void (Foo::*fVPtr)( int, int*, int& ) = &Foo::VirtualMemberFunction;
+    void (Foo::*fVCPtr)( int, int*, int& ) const = &Foo::VirtualConstMemberFunction;
+    void (ObjectForConstPtr::*fCPtr2)( int, int*, int& ) const = &ObjectForConstPtr::ConstMemberFunction;
+
+    (foop->*fPtr)(test, &test, test);
+    (foop2->*fVPtr)(test, &test, test);
+    (foop2->*fVCPtr)(test, &test, test);
+    (foop3->*fCPtr2)(test, &test, test);
+  }
+
+  // Looks like everything ran.
+  ASSERT_TRUE(true);
+}
diff --git a/xpcom/tests/gtest/TestObserverArray.cpp b/xpcom/tests/gtest/TestObserverArray.cpp
new file mode 100644
index 000000000..d907619be
--- /dev/null
+++ b/xpcom/tests/gtest/TestObserverArray.cpp
@@ -0,0 +1,167 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+// vim:cindent:ts=4:et:sw=4:
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsTObserverArray.h"
+#include "gtest/gtest.h"
+
+using namespace mozilla;
+
+typedef nsTObserverArray<int> IntArray;
+
+#define DO_TEST(_type, _exp, _code)                                   \
+  do {                                                                \
+    ++testNum;                                                        \
+    count = 0;                                                        \
+    IntArray::_type iter(arr);                                        \
+    while (iter.HasMore() && count != ArrayLength(_exp)) {            \
+      _code                                                           \
+      int next = iter.GetNext();                                      \
+      int expected = _exp[count++];                                   \
+      ASSERT_EQ(next, expected) << "During test " << testNum << " at position " << count - 1;  \
+    }                                                                 \
+    ASSERT_FALSE(iter.HasMore()) << "During test " << testNum << ", iterator ran over"; \
+    ASSERT_EQ(count, ArrayLength(_exp)) << "During test " << testNum << ", iterator finished too early"; \
+  } while (0)
+
+TEST(ObserverArray, Tests)
+{
+  IntArray arr;
+  arr.AppendElement(3);
+  arr.AppendElement(4);
+
+  size_t count;
+  int testNum = 0;
+
+  // Basic sanity
+  static int test1Expected[] = { 3, 4 };
+  DO_TEST(ForwardIterator, test1Expected, { /* nothing */ });
+
+  // Appends
+  static int test2Expected[] = { 3, 4, 2 };
+  DO_TEST(ForwardIterator, test2Expected,
+          if (count == 1) arr.AppendElement(2);
+          );
+  DO_TEST(ForwardIterator, test2Expected, { /* nothing */ });
+
+  DO_TEST(EndLimitedIterator, test2Expected,
+          if (count == 1) arr.AppendElement(5);
+          );
+
+  static int test5Expected[] = { 3, 4, 2, 5 };
+  DO_TEST(ForwardIterator, test5Expected, { /* nothing */ });
+
+  // Removals
+  DO_TEST(ForwardIterator, test5Expected,
+          if (count == 1) arr.RemoveElementAt(0);
+          );
+
+  static int test7Expected[] = { 4, 2, 5 };
+  DO_TEST(ForwardIterator, test7Expected, { /* nothing */ });
+
+  static int test8Expected[] = { 4, 5 };
+  DO_TEST(ForwardIterator, test8Expected,
+          if (count == 1) arr.RemoveElementAt(1);
+          );
+  DO_TEST(ForwardIterator, test8Expected, { /* nothing */ });
+
+  arr.AppendElement(2);
+  arr.AppendElementUnlessExists(6);
+  static int test10Expected[] = { 4, 5, 2, 6 };
+  DO_TEST(ForwardIterator, test10Expected, { /* nothing */ });
+
+  arr.AppendElementUnlessExists(5);
+  DO_TEST(ForwardIterator, test10Expected, { /* nothing */ });
+
+  static int test12Expected[] = { 4, 5, 6 };
+  DO_TEST(ForwardIterator, test12Expected,
+          if (count == 1) arr.RemoveElementAt(2);
+          );
+  DO_TEST(ForwardIterator, test12Expected, { /* nothing */ });
+
+  // Removals + Appends
+  static int test14Expected[] = { 4, 6, 7 };
+  DO_TEST(ForwardIterator, test14Expected,
+          if (count == 1) {
+            arr.RemoveElementAt(1);
+            arr.AppendElement(7);
+          }
+          );
+  DO_TEST(ForwardIterator, test14Expected, { /* nothing */ });
+
+  arr.AppendElement(2);
+  static int test16Expected[] = { 4, 6, 7, 2 };
+  DO_TEST(ForwardIterator, test16Expected, { /* nothing */ });
+
+  static int test17Expected[] = { 4, 7, 2 };
+  DO_TEST(EndLimitedIterator, test17Expected,
+          if (count == 1) {
+            arr.RemoveElementAt(1);
+            arr.AppendElement(8);
+          }
+          );
+
+  static int test18Expected[] = { 4, 7, 2, 8 };
+  DO_TEST(ForwardIterator, test18Expected, { /* nothing */ });
+
+  // Prepends
+  arr.PrependElementUnlessExists(3);
+  static int test19Expected[] = { 3, 4, 7, 2, 8 };
+  DO_TEST(ForwardIterator, test19Expected, { /* nothing */ });
+
+  arr.PrependElementUnlessExists(7);
+  DO_TEST(ForwardIterator, test19Expected, { /* nothing */ });
+
+  DO_TEST(ForwardIterator, test19Expected,
+          if (count == 1) {
+            arr.PrependElementUnlessExists(9);
+          }
+          );
+
+  static int test22Expected[] = { 9, 3, 4, 7, 2, 8 };
+  DO_TEST(ForwardIterator, test22Expected, { });
+
+  // BackwardIterator
+  static int test23Expected[] = { 8, 2, 7, 4, 3, 9 };
+  DO_TEST(BackwardIterator, test23Expected, );
+
+  // Removals
+  static int test24Expected[] = { 8, 2, 7, 4, 9 };
+  DO_TEST(BackwardIterator, test24Expected,
+          if (count == 1) arr.RemoveElementAt(1);
+          );
+
+  // Appends
+  DO_TEST(BackwardIterator, test24Expected,
+          if (count == 1) arr.AppendElement(1);
+          );
+
+  static int test26Expected[] = { 1, 8, 2, 7, 4, 9 };
+  DO_TEST(BackwardIterator, test26Expected, );
+
+  // Prepends
+  static int test27Expected[] = { 1, 8, 2, 7, 4, 9, 3 };
+  DO_TEST(BackwardIterator, test27Expected,
+          if (count == 1) arr.PrependElementUnlessExists(3);
+          );
+
+  // Removal using Iterator
+  DO_TEST(BackwardIterator, test27Expected,
+          // when this code runs, |GetNext()| has only been called once, so
+          // this actually removes the very first element
+          if (count == 1) iter.Remove();
+          );
+
+  static int test28Expected[] = { 8, 2, 7, 4, 9, 3 };
+  DO_TEST(BackwardIterator, test28Expected, );
+
+  /**
+   * Note: _code is executed before the call to GetNext(), it can therefore not
+   * test the case of prepending when the BackwardIterator already returned the
+   * first element.
+   * In that case BackwardIterator does not traverse the newly prepended Element
+   */
+
+}
diff --git a/xpcom/tests/gtest/TestObserverService.cpp b/xpcom/tests/gtest/TestObserverService.cpp
new file mode 100644
index 000000000..d4eb51a7e
--- /dev/null
+++ b/xpcom/tests/gtest/TestObserverService.cpp
@@ -0,0 +1,288 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.h"
+#include "nsIComponentManager.h"
+#include "nsIObserverService.h"
+#include "nsIObserver.h"
+#include "nsISimpleEnumerator.h"
+#include "nsComponentManagerUtils.h"
+
+#include "nsCOMPtr.h"
+#include "nsString.h"
+#include "nsWeakReference.h"
+
+#include "mozilla/RefPtr.h"
+
+#include "gtest/gtest.h"
+
+static void testResult( nsresult rv ) {
+  EXPECT_TRUE(NS_SUCCEEDED(rv)) << "0x" << std::hex << (int)rv;
+}
+
+class TestObserver final : public nsIObserver,
+  public nsSupportsWeakReference
+{
+public:
+  explicit TestObserver( const nsAString &name )
+    : mName( name )
+    , mObservations( 0 ) {
+    }
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+
+  nsString mName;
+  int mObservations;
+  static int sTotalObservations;
+
+  nsString mExpectedData;
+
+private:
+  ~TestObserver() {}
+};
+
+NS_IMPL_ISUPPORTS( TestObserver, nsIObserver, nsISupportsWeakReference )
+
+int TestObserver::sTotalObservations;
+
+NS_IMETHODIMP
+TestObserver::Observe(nsISupports *aSubject,
+    const char *aTopic,
+    const char16_t *someData ) {
+  mObservations++;
+  sTotalObservations++;
+
+  if (!mExpectedData.IsEmpty()) {
+    EXPECT_TRUE(mExpectedData.Equals(someData));
+  }
+
+  return NS_OK;
+}
+
+static nsISupports* ToSupports(TestObserver* aObs)
+{
+  return static_cast<nsIObserver*>(aObs);
+}
+
+static void TestExpectedCount(
+    nsIObserverService* svc,
+    const char* topic,
+    size_t expected)
+{
+  nsCOMPtr<nsISimpleEnumerator> e;
+  nsresult rv = svc->EnumerateObservers(topic, getter_AddRefs(e));
+  testResult(rv);
+  EXPECT_TRUE(e);
+
+  bool hasMore = false;
+  rv = e->HasMoreElements(&hasMore);
+  testResult(rv);
+
+  if (expected == 0) {
+    EXPECT_FALSE(hasMore);
+    return;
+  }
+
+  size_t count = 0;
+  while (hasMore) {
+    count++;
+
+    // Grab the element.
+    nsCOMPtr<nsISupports> supports;
+    e->GetNext(getter_AddRefs(supports));
+    ASSERT_TRUE(supports);
+
+    // Move on.
+    rv = e->HasMoreElements(&hasMore);
+    testResult(rv);
+  }
+
+  EXPECT_EQ(count, expected);
+}
+
+TEST(ObserverService, Creation)
+{
+  nsresult rv;
+  nsCOMPtr<nsIObserverService> svc =
+    do_CreateInstance("@mozilla.org/observer-service;1", &rv);
+
+  ASSERT_EQ(rv, NS_OK);
+  ASSERT_TRUE(svc);
+}
+
+TEST(ObserverService, AddObserver)
+{
+  nsCOMPtr<nsIObserverService> svc =
+    do_CreateInstance("@mozilla.org/observer-service;1");
+
+  // Add a strong ref.
+  RefPtr<TestObserver> a = new TestObserver(NS_LITERAL_STRING("A"));
+  nsresult rv = svc->AddObserver(a, "Foo", false);
+  testResult(rv);
+
+  // Add a few weak ref.
+  RefPtr<TestObserver> b = new TestObserver(NS_LITERAL_STRING("B"));
+  rv = svc->AddObserver(b, "Bar", true);
+  testResult(rv);
+}
+
+TEST(ObserverService, RemoveObserver)
+{
+  nsCOMPtr<nsIObserverService> svc =
+    do_CreateInstance("@mozilla.org/observer-service;1");
+
+  RefPtr<TestObserver> a = new TestObserver(NS_LITERAL_STRING("A"));
+  RefPtr<TestObserver> b = new TestObserver(NS_LITERAL_STRING("B"));
+  RefPtr<TestObserver> c = new TestObserver(NS_LITERAL_STRING("C"));
+
+  svc->AddObserver(a, "Foo", false);
+  svc->AddObserver(b, "Foo", true);
+
+  // Remove from non-existent topic.
+  nsresult rv = svc->RemoveObserver(a, "Bar");
+  ASSERT_TRUE(NS_FAILED(rv));
+
+  // Remove a.
+  testResult(svc->RemoveObserver(a, "Foo"));
+
+  // Remove b.
+  testResult(svc->RemoveObserver(b, "Foo"));
+
+  // Attempt to remove c.
+  rv = svc->RemoveObserver(c, "Foo");
+  ASSERT_TRUE(NS_FAILED(rv));
+}
+
+TEST(ObserverService, EnumerateEmpty)
+{
+  nsCOMPtr<nsIObserverService> svc =
+    do_CreateInstance("@mozilla.org/observer-service;1");
+
+  // Try with no observers.
+  TestExpectedCount(svc, "A", 0);
+
+  // Now add an observer and enumerate an unobserved topic.
+  RefPtr<TestObserver> a = new TestObserver(NS_LITERAL_STRING("A"));
+  testResult(svc->AddObserver(a, "Foo", false));
+
+  TestExpectedCount(svc, "A", 0);
+}
+
+TEST(ObserverService, Enumerate)
+{
+  nsCOMPtr<nsIObserverService> svc =
+    do_CreateInstance("@mozilla.org/observer-service;1");
+
+  const size_t kFooCount = 10;
+  for (size_t i = 0; i < kFooCount; i++) {
+    RefPtr<TestObserver> a = new TestObserver(NS_LITERAL_STRING("A"));
+    testResult(svc->AddObserver(a, "Foo", false));
+  }
+
+  const size_t kBarCount = kFooCount / 2;
+  for (size_t i = 0; i < kBarCount; i++) {
+    RefPtr<TestObserver> a = new TestObserver(NS_LITERAL_STRING("A"));
+    testResult(svc->AddObserver(a, "Bar", false));
+  }
+
+  // Enumerate "Foo".
+  TestExpectedCount(svc, "Foo", kFooCount);
+
+  // Enumerate "Bar".
+  TestExpectedCount(svc, "Bar", kBarCount);
+}
+
+TEST(ObserverService, EnumerateWeakRefs)
+{
+  nsCOMPtr<nsIObserverService> svc =
+    do_CreateInstance("@mozilla.org/observer-service;1");
+
+  const size_t kFooCount = 10;
+  for (size_t i = 0; i < kFooCount; i++) {
+    RefPtr<TestObserver> a = new TestObserver(NS_LITERAL_STRING("A"));
+    testResult(svc->AddObserver(a, "Foo", true));
+  }
+
+  // All refs are out of scope, expect enumeration to be empty.
+  TestExpectedCount(svc, "Foo", 0);
+
+  // Now test a mixture.
+  for (size_t i = 0; i < kFooCount; i++) {
+    RefPtr<TestObserver> a = new TestObserver(NS_LITERAL_STRING("A"));
+    RefPtr<TestObserver> b = new TestObserver(NS_LITERAL_STRING("B"));
+
+    // Register a as weak for "Foo".
+    testResult(svc->AddObserver(a, "Foo", true));
+
+    // Register b as strong for "Foo".
+    testResult(svc->AddObserver(b, "Foo", false));
+  }
+
+  // Expect the b instances to stick around.
+  TestExpectedCount(svc, "Foo", kFooCount);
+
+  // Now add a couple weak refs, but don't go out of scope.
+  RefPtr<TestObserver> a = new TestObserver(NS_LITERAL_STRING("A"));
+  testResult(svc->AddObserver(a, "Foo", true));
+  RefPtr<TestObserver> b = new TestObserver(NS_LITERAL_STRING("B"));
+  testResult(svc->AddObserver(b, "Foo", true));
+
+  // Expect all the observers from before and the two new ones.
+  TestExpectedCount(svc, "Foo", kFooCount + 2);
+}
+
+TEST(ObserverService, TestNotify)
+{
+  nsCString topicA; topicA.Assign( "topic-A" );
+  nsCString topicB; topicB.Assign( "topic-B" );
+
+  nsCOMPtr<nsIObserverService> svc =
+    do_CreateInstance("@mozilla.org/observer-service;1");
+
+  RefPtr<TestObserver> aObserver = new TestObserver(NS_LITERAL_STRING("Observer-A"));
+  RefPtr<TestObserver> bObserver = new TestObserver(NS_LITERAL_STRING("Observer-B"));
+
+  // Add two observers for topicA.
+  testResult(svc->AddObserver(aObserver, topicA.get(), false));
+  testResult(svc->AddObserver(bObserver, topicA.get(), false));
+
+  // Add one observer for topicB.
+  testResult(svc->AddObserver(bObserver, topicB.get(), false));
+
+  // Notify topicA.
+  NS_NAMED_LITERAL_STRING(dataA, "Testing Notify(observer-A, topic-A)");
+  aObserver->mExpectedData = dataA;
+  bObserver->mExpectedData = dataA;
+  nsresult rv =
+      svc->NotifyObservers(ToSupports(aObserver), topicA.get(), dataA.get());
+  testResult(rv);
+  ASSERT_EQ(aObserver->mObservations, 1);
+  ASSERT_EQ(bObserver->mObservations, 1);
+
+  // Notify topicB.
+  NS_NAMED_LITERAL_STRING(dataB, "Testing Notify(observer-B, topic-B)");
+  bObserver->mExpectedData = dataB;
+  rv = svc->NotifyObservers(ToSupports(bObserver), topicB.get(), dataB.get());
+  testResult(rv);
+  ASSERT_EQ(aObserver->mObservations, 1);
+  ASSERT_EQ(bObserver->mObservations, 2);
+
+  // Remove one of the topicA observers, make sure it's not notified.
+  testResult(svc->RemoveObserver(aObserver, topicA.get()));
+
+  // Notify topicA, only bObserver is expected to be notified.
+  bObserver->mExpectedData = dataA;
+  rv = svc->NotifyObservers(ToSupports(aObserver), topicA.get(), dataA.get());
+  testResult(rv);
+  ASSERT_EQ(aObserver->mObservations, 1);
+  ASSERT_EQ(bObserver->mObservations, 3);
+
+  // Remove the other topicA observer, make sure none are notified.
+  testResult(svc->RemoveObserver(bObserver, topicA.get()));
+  rv = svc->NotifyObservers(ToSupports(aObserver), topicA.get(), dataA.get());
+  testResult(rv);
+  ASSERT_EQ(aObserver->mObservations, 1);
+  ASSERT_EQ(bObserver->mObservations, 3);
+}
diff --git a/xpcom/tests/gtest/TestPLDHash.cpp b/xpcom/tests/gtest/TestPLDHash.cpp
new file mode 100644
index 000000000..e7a73ae1b
--- /dev/null
+++ b/xpcom/tests/gtest/TestPLDHash.cpp
@@ -0,0 +1,368 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "PLDHashTable.h"
+#include "nsCOMPtr.h"
+#include "nsServiceManagerUtils.h"
+#include "gtest/gtest.h"
+
+// This test mostly focuses on edge cases. But more coverage of normal
+// operations wouldn't be a bad thing.
+
+#ifdef XP_UNIX
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+// This global variable is defined in toolkit/xre/nsSigHandlers.cpp.
+extern unsigned int _gdb_sleep_duration;
+#endif
+
+#ifdef MOZ_CRASHREPORTER
+#include "nsICrashReporter.h"
+#endif
+
+// We can test that certain operations cause expected aborts by forking
+// and then checking that the child aborted in the expected way (i.e. via
+// MOZ_CRASH). We skip this for the following configurations.
+// - On Windows, because it doesn't have fork().
+// - On non-DEBUG builds, because the crashes cause the crash reporter to pop
+//   up when running this test locally, which is surprising and annoying.
+// - On ASAN builds, because ASAN alters the way a MOZ_CRASHing process
+//   terminates, which makes it harder to test if the right thing has occurred.
+void
+TestCrashyOperation(void (*aCrashyOperation)())
+{
+#if defined(XP_UNIX) && defined(DEBUG) && !defined(MOZ_ASAN)
+  // We're about to trigger a crash. When it happens don't pause to allow GDB
+  // to be attached.
+  unsigned int old_gdb_sleep_duration = _gdb_sleep_duration;
+  _gdb_sleep_duration = 0;
+
+  int pid = fork();
+  ASSERT_NE(pid, -1);
+
+  if (pid == 0) {
+    // Disable the crashreporter -- writing a crash dump in the child will
+    // prevent the parent from writing a subsequent dump. Crashes here are
+    // expected, so we don't want their stacks to show up in the log anyway.
+#ifdef MOZ_CRASHREPORTER
+    nsCOMPtr<nsICrashReporter> crashreporter =
+      do_GetService("@mozilla.org/toolkit/crash-reporter;1");
+    if (crashreporter) {
+      crashreporter->SetEnabled(false);
+    }
+#endif
+
+    // Child: perform the crashy operation.
+    fprintf(stderr, "TestCrashyOperation: The following crash is expected. Do not panic.\n");
+    aCrashyOperation();
+    fprintf(stderr, "TestCrashyOperation: didn't crash?!\n");
+    ASSERT_TRUE(false);   // shouldn't reach here
+  }
+
+  // Parent: check that child crashed as expected.
+  int status;
+  ASSERT_NE(waitpid(pid, &status, 0), -1);
+
+  // The path taken here depends on the platform and configuration.
+  ASSERT_TRUE(WIFEXITED(status) || WTERMSIG(status));
+  if (WIFEXITED(status)) {
+    // This occurs if the ah_crap_handler() is run, i.e. we caught the crash.
+    // It returns the number of the caught signal.
+    int signum = WEXITSTATUS(status);
+    if (signum != SIGSEGV && signum != SIGBUS) {
+      fprintf(stderr, "TestCrashyOperation 'exited' failure: %d\n", signum);
+      ASSERT_TRUE(false);
+    }
+  } else if (WIFSIGNALED(status)) {
+    // This one occurs if we didn't catch the crash. The exit code is the
+    // number of the terminating signal.
+    int signum = WTERMSIG(status);
+    if (signum != SIGSEGV && signum != SIGBUS) {
+      fprintf(stderr, "TestCrashyOperation 'signaled' failure: %d\n", signum);
+      ASSERT_TRUE(false);
+    }
+  }
+
+  _gdb_sleep_duration = old_gdb_sleep_duration;
+#endif
+}
+
+void
+InitCapacityOk_InitialLengthTooBig()
+{
+  PLDHashTable t(PLDHashTable::StubOps(), sizeof(PLDHashEntryStub),
+                 PLDHashTable::kMaxInitialLength + 1);
+}
+
+void
+InitCapacityOk_InitialEntryStoreTooBig()
+{
+  // Try the smallest disallowed power-of-two entry store size, which is 2^32
+  // bytes (which overflows to 0). (Note that the 2^23 *length* gets converted
+  // to a 2^24 *capacity*.)
+  PLDHashTable t(PLDHashTable::StubOps(), (uint32_t)1 << 23, (uint32_t)1 << 8);
+}
+
+TEST(PLDHashTableTest, InitCapacityOk)
+{
+  // Try the largest allowed capacity.  With kMaxCapacity==1<<26, this
+  // would allocate (if we added an element) 0.5GB of entry store on 32-bit
+  // platforms and 1GB on 64-bit platforms.
+  PLDHashTable t1(PLDHashTable::StubOps(), sizeof(PLDHashEntryStub),
+                  PLDHashTable::kMaxInitialLength);
+
+  // Try the largest allowed power-of-two entry store size, which is 2^31 bytes
+  // (Note that the 2^23 *length* gets converted to a 2^24 *capacity*.)
+  PLDHashTable t2(PLDHashTable::StubOps(), (uint32_t)1 << 23, (uint32_t)1 << 7);
+
+  // Try a too-large capacity (which aborts).
+  TestCrashyOperation(InitCapacityOk_InitialLengthTooBig);
+
+  // Try a large capacity combined with a large entry size that when multiplied
+  // overflow (causing abort).
+  TestCrashyOperation(InitCapacityOk_InitialEntryStoreTooBig);
+
+  // Ideally we'd also try a large-but-ok capacity that almost but doesn't
+  // quite overflow, but that would result in allocating slightly less than 4
+  // GiB of entry storage. That would be very likely to fail on 32-bit
+  // platforms, so such a test wouldn't be reliable.
+}
+
+TEST(PLDHashTableTest, LazyStorage)
+{
+  PLDHashTable t(PLDHashTable::StubOps(), sizeof(PLDHashEntryStub));
+
+  // PLDHashTable allocates entry storage lazily. Check that all the non-add
+  // operations work appropriately when the table is empty and the storage
+  // hasn't yet been allocated.
+
+  ASSERT_EQ(t.Capacity(), 0u);
+  ASSERT_EQ(t.EntrySize(), sizeof(PLDHashEntryStub));
+  ASSERT_EQ(t.EntryCount(), 0u);
+  ASSERT_EQ(t.Generation(), 0u);
+
+  ASSERT_TRUE(!t.Search((const void*)1));
+
+  // No result to check here, but call it to make sure it doesn't crash.
+  t.Remove((const void*)2);
+
+  for (auto iter = t.Iter(); !iter.Done(); iter.Next()) {
+    ASSERT_TRUE(false); // shouldn't hit this on an empty table
+  }
+
+  ASSERT_EQ(t.ShallowSizeOfExcludingThis(moz_malloc_size_of), 0u);
+}
+
+// A trivial hash function is good enough here. It's also super-fast for the
+// GrowToMaxCapacity test because we insert the integers 0.., which means it's
+// collision-free.
+static PLDHashNumber
+TrivialHash(const void *key)
+{
+  return (PLDHashNumber)(size_t)key;
+}
+
+static void
+TrivialInitEntry(PLDHashEntryHdr* aEntry, const void* aKey)
+{
+  auto entry = static_cast<PLDHashEntryStub*>(aEntry);
+  entry->key = aKey;
+}
+
+static const PLDHashTableOps trivialOps = {
+  TrivialHash,
+  PLDHashTable::MatchEntryStub,
+  PLDHashTable::MoveEntryStub,
+  PLDHashTable::ClearEntryStub,
+  TrivialInitEntry
+};
+
+TEST(PLDHashTableTest, MoveSemantics)
+{
+  PLDHashTable t1(&trivialOps, sizeof(PLDHashEntryStub));
+  t1.Add((const void*)88);
+  PLDHashTable t2(&trivialOps, sizeof(PLDHashEntryStub));
+  t2.Add((const void*)99);
+
+  t1 = mozilla::Move(t1);   // self-move
+
+  t1 = mozilla::Move(t2);   // empty overwritten with empty
+
+  PLDHashTable t3(&trivialOps, sizeof(PLDHashEntryStub));
+  PLDHashTable t4(&trivialOps, sizeof(PLDHashEntryStub));
+  t3.Add((const void*)88);
+
+  t3 = mozilla::Move(t4);   // non-empty overwritten with empty
+
+  PLDHashTable t5(&trivialOps, sizeof(PLDHashEntryStub));
+  PLDHashTable t6(&trivialOps, sizeof(PLDHashEntryStub));
+  t6.Add((const void*)88);
+
+  t5 = mozilla::Move(t6);   // empty overwritten with non-empty
+
+  PLDHashTable t7(&trivialOps, sizeof(PLDHashEntryStub));
+  PLDHashTable t8(mozilla::Move(t7));  // new table constructed with uninited
+
+  PLDHashTable t9(&trivialOps, sizeof(PLDHashEntryStub));
+  t9.Add((const void*)88);
+  PLDHashTable t10(mozilla::Move(t9));  // new table constructed with inited
+}
+
+TEST(PLDHashTableTest, Clear)
+{
+  PLDHashTable t1(&trivialOps, sizeof(PLDHashEntryStub));
+
+  t1.Clear();
+  ASSERT_EQ(t1.EntryCount(), 0u);
+
+  t1.ClearAndPrepareForLength(100);
+  ASSERT_EQ(t1.EntryCount(), 0u);
+
+  t1.Add((const void*)77);
+  t1.Add((const void*)88);
+  t1.Add((const void*)99);
+  ASSERT_EQ(t1.EntryCount(), 3u);
+
+  t1.Clear();
+  ASSERT_EQ(t1.EntryCount(), 0u);
+
+  t1.Add((const void*)55);
+  t1.Add((const void*)66);
+  t1.Add((const void*)77);
+  t1.Add((const void*)88);
+  t1.Add((const void*)99);
+  ASSERT_EQ(t1.EntryCount(), 5u);
+
+  t1.ClearAndPrepareForLength(8192);
+  ASSERT_EQ(t1.EntryCount(), 0u);
+}
+
+TEST(PLDHashTableTest, Iterator)
+{
+  PLDHashTable t(&trivialOps, sizeof(PLDHashEntryStub));
+
+  // Explicitly test the move constructor. We do this because, due to copy
+  // elision, compilers might optimize away move constructor calls for normal
+  // iterator use.
+  {
+    PLDHashTable::Iterator iter1(&t);
+    PLDHashTable::Iterator iter2(mozilla::Move(iter1));
+  }
+
+  // Iterate through the empty table.
+  for (PLDHashTable::Iterator iter(&t); !iter.Done(); iter.Next()) {
+    (void) iter.Get();
+    ASSERT_TRUE(false); // shouldn't hit this
+  }
+
+  // Add three entries.
+  t.Add((const void*)77);
+  t.Add((const void*)88);
+  t.Add((const void*)99);
+
+  // Check the iterator goes through each entry once.
+  bool saw77 = false, saw88 = false, saw99 = false;
+  int n = 0;
+  for (auto iter(t.Iter()); !iter.Done(); iter.Next()) {
+    auto entry = static_cast<PLDHashEntryStub*>(iter.Get());
+    if (entry->key == (const void*)77) {
+      saw77 = true;
+    }
+    if (entry->key == (const void*)88) {
+      saw88 = true;
+    }
+    if (entry->key == (const void*)99) {
+      saw99 = true;
+    }
+    n++;
+  }
+  ASSERT_TRUE(saw77 && saw88 && saw99 && n == 3);
+
+  t.Clear();
+
+  // First, we insert 64 items, which results in a capacity of 128, and a load
+  // factor of 50%.
+  for (intptr_t i = 0; i < 64; i++) {
+    t.Add((const void*)i);
+  }
+  ASSERT_EQ(t.EntryCount(), 64u);
+  ASSERT_EQ(t.Capacity(), 128u);
+
+  // The first removing iterator does no removing; capacity and entry count are
+  // unchanged.
+  for (PLDHashTable::Iterator iter(&t); !iter.Done(); iter.Next()) {
+    (void) iter.Get();
+  }
+  ASSERT_EQ(t.EntryCount(), 64u);
+  ASSERT_EQ(t.Capacity(), 128u);
+
+  // The second removing iterator removes 16 items. This reduces the load
+  // factor to 37.5% (48 / 128), which isn't low enough to shrink the table.
+  for (auto iter = t.Iter(); !iter.Done(); iter.Next()) {
+    auto entry = static_cast<PLDHashEntryStub*>(iter.Get());
+    if ((intptr_t)(entry->key) % 4 == 0) {
+      iter.Remove();
+    }
+  }
+  ASSERT_EQ(t.EntryCount(), 48u);
+  ASSERT_EQ(t.Capacity(), 128u);
+
+  // The third removing iterator removes another 16 items. This reduces
+  // the load factor to 25% (32 / 128), so the table is shrunk.
+  for (auto iter = t.Iter(); !iter.Done(); iter.Next()) {
+    auto entry = static_cast<PLDHashEntryStub*>(iter.Get());
+    if ((intptr_t)(entry->key) % 2 == 0) {
+      iter.Remove();
+    }
+  }
+  ASSERT_EQ(t.EntryCount(), 32u);
+  ASSERT_EQ(t.Capacity(), 64u);
+
+  // The fourth removing iterator removes all remaining items. This reduces
+  // the capacity to the minimum.
+  for (auto iter = t.Iter(); !iter.Done(); iter.Next()) {
+    iter.Remove();
+  }
+  ASSERT_EQ(t.EntryCount(), 0u);
+  ASSERT_EQ(t.Capacity(), unsigned(PLDHashTable::kMinCapacity));
+}
+
+// This test involves resizing a table repeatedly up to 512 MiB in size. On
+// 32-bit platforms (Win32, Android) it sometimes OOMs, causing the test to
+// fail. (See bug 931062 and bug 1267227.) Therefore, we only run it on 64-bit
+// platforms where OOM is much less likely.
+//
+// Also, it's slow, and so should always be last.
+#ifdef HAVE_64BIT_BUILD
+TEST(PLDHashTableTest, GrowToMaxCapacity)
+{
+  // This is infallible.
+  PLDHashTable* t =
+    new PLDHashTable(&trivialOps, sizeof(PLDHashEntryStub), 128);
+
+  // Keep inserting elements until failure occurs because the table is full.
+  size_t numInserted = 0;
+  while (true) {
+    if (!t->Add((const void*)numInserted, mozilla::fallible)) {
+      break;
+    }
+    numInserted++;
+  }
+
+  // We stop when the element count is 96.875% of PLDHashTable::kMaxCapacity
+  // (see MaxLoadOnGrowthFailure()).
+  if (numInserted !=
+      PLDHashTable::kMaxCapacity - (PLDHashTable::kMaxCapacity >> 5)) {
+    delete t;
+    ASSERT_TRUE(false);
+  }
+
+  delete t;
+}
+#endif
+
diff --git a/xpcom/tests/gtest/TestPipes.cpp b/xpcom/tests/gtest/TestPipes.cpp
new file mode 100644
index 000000000..87b923008
--- /dev/null
+++ b/xpcom/tests/gtest/TestPipes.cpp
@@ -0,0 +1,1097 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <algorithm>
+#include "gtest/gtest.h"
+#include "Helpers.h"
+#include "mozilla/ReentrantMonitor.h"
+#include "nsCOMPtr.h"
+#include "nsCRT.h"
+#include "nsIAsyncInputStream.h"
+#include "nsIAsyncOutputStream.h"
+#include "nsIBufferedStreams.h"
+#include "nsIClassInfo.h"
+#include "nsICloneableInputStream.h"
+#include "nsIInputStream.h"
+#include "nsIOutputStream.h"
+#include "nsIPipe.h"
+#include "nsISeekableStream.h"
+#include "nsIThread.h"
+#include "nsIRunnable.h"
+#include "nsStreamUtils.h"
+#include "nsString.h"
+#include "nsThreadUtils.h"
+#include "prprf.h"
+#include "prinrval.h"
+
+using namespace mozilla;
+
+#define ITERATIONS      33333
+char kTestPattern[] = "My hovercraft is full of eels.\n";
+
+bool gTrace = false;
+
+static nsresult
+WriteAll(nsIOutputStream *os, const char *buf, uint32_t bufLen, uint32_t *lenWritten)
+{
+    const char *p = buf;
+    *lenWritten = 0;
+    while (bufLen) {
+        uint32_t n;
+        nsresult rv = os->Write(p, bufLen, &n);
+        if (NS_FAILED(rv)) return rv;
+        p += n;
+        bufLen -= n;
+        *lenWritten += n;
+    }
+    return NS_OK;
+}
+
+class nsReceiver final : public nsIRunnable {
+public:
+    NS_DECL_THREADSAFE_ISUPPORTS
+
+    NS_IMETHOD Run() override {
+        nsresult rv;
+        char buf[101];
+        uint32_t count;
+        PRIntervalTime start = PR_IntervalNow();
+        while (true) {
+            rv = mIn->Read(buf, 100, &count);
+            if (NS_FAILED(rv)) {
+                printf("read failed\n");
+                break;
+            }
+            if (count == 0) {
+//                printf("EOF count = %d\n", mCount);
+                break;
+            }
+
+            if (gTrace) {
+                buf[count] = '\0';
+                printf("read: %s\n", buf);
+            }
+            mCount += count;
+        }
+        PRIntervalTime end = PR_IntervalNow();
+        printf("read  %d bytes, time = %dms\n", mCount,
+               PR_IntervalToMilliseconds(end - start));
+        return rv;
+    }
+
+    explicit nsReceiver(nsIInputStream* in) : mIn(in), mCount(0) {
+    }
+
+    uint32_t GetBytesRead() { return mCount; }
+
+private:
+    ~nsReceiver() {}
+
+protected:
+    nsCOMPtr<nsIInputStream> mIn;
+    uint32_t            mCount;
+};
+
+NS_IMPL_ISUPPORTS(nsReceiver, nsIRunnable)
+
+nsresult
+TestPipe(nsIInputStream* in, nsIOutputStream* out)
+{
+    RefPtr<nsReceiver> receiver = new nsReceiver(in);
+    if (!receiver)
+        return NS_ERROR_OUT_OF_MEMORY;
+
+    nsresult rv;
+
+    nsCOMPtr<nsIThread> thread;
+    rv = NS_NewThread(getter_AddRefs(thread), receiver);
+    if (NS_FAILED(rv)) return rv;
+
+    uint32_t total = 0;
+    PRIntervalTime start = PR_IntervalNow();
+    for (uint32_t i = 0; i < ITERATIONS; i++) {
+        uint32_t writeCount;
+        char *buf = PR_smprintf("%d %s", i, kTestPattern);
+        uint32_t len = strlen(buf);
+        rv = WriteAll(out, buf, len, &writeCount);
+        if (gTrace) {
+            printf("wrote: ");
+            for (uint32_t j = 0; j < writeCount; j++) {
+                putc(buf[j], stdout);
+            }
+            printf("\n");
+        }
+        PR_smprintf_free(buf);
+        if (NS_FAILED(rv)) return rv;
+        total += writeCount;
+    }
+    rv = out->Close();
+    if (NS_FAILED(rv)) return rv;
+
+    PRIntervalTime end = PR_IntervalNow();
+
+    thread->Shutdown();
+
+    printf("wrote %d bytes, time = %dms\n", total,
+           PR_IntervalToMilliseconds(end - start));
+    EXPECT_EQ(receiver->GetBytesRead(), total);
+
+    return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+class nsShortReader final : public nsIRunnable {
+public:
+    NS_DECL_THREADSAFE_ISUPPORTS
+
+    NS_IMETHOD Run() override {
+        nsresult rv;
+        char buf[101];
+        uint32_t count;
+        uint32_t total = 0;
+        while (true) {
+            //if (gTrace)
+            //    printf("calling Read\n");
+            rv = mIn->Read(buf, 100, &count);
+            if (NS_FAILED(rv)) {
+                printf("read failed\n");
+                break;
+            }
+            if (count == 0) {
+                break;
+            }
+
+            if (gTrace) {
+                // For next |printf()| call and possible others elsewhere.
+                buf[count] = '\0';
+
+                printf("read %d bytes: %s\n", count, buf);
+            }
+
+            Received(count);
+            total += count;
+        }
+        printf("read  %d bytes\n", total);
+        return rv;
+    }
+
+    explicit nsShortReader(nsIInputStream* in) : mIn(in), mReceived(0) {
+        mMon = new ReentrantMonitor("nsShortReader");
+    }
+
+    void Received(uint32_t count) {
+        ReentrantMonitorAutoEnter mon(*mMon);
+        mReceived += count;
+        mon.Notify();
+    }
+
+    uint32_t WaitForReceipt(const uint32_t aWriteCount) {
+        ReentrantMonitorAutoEnter mon(*mMon);
+        uint32_t result = mReceived;
+
+        while (result < aWriteCount) {
+            mon.Wait();
+
+            EXPECT_TRUE(mReceived > result);
+            result = mReceived;
+        }
+
+        mReceived = 0;
+        return result;
+    }
+
+private:
+    ~nsShortReader() {}
+
+protected:
+    nsCOMPtr<nsIInputStream> mIn;
+    uint32_t                 mReceived;
+    ReentrantMonitor*        mMon;
+};
+
+NS_IMPL_ISUPPORTS(nsShortReader, nsIRunnable)
+
+nsresult
+TestShortWrites(nsIInputStream* in, nsIOutputStream* out)
+{
+    RefPtr<nsShortReader> receiver = new nsShortReader(in);
+    if (!receiver)
+        return NS_ERROR_OUT_OF_MEMORY;
+
+    nsresult rv;
+
+    nsCOMPtr<nsIThread> thread;
+    rv = NS_NewThread(getter_AddRefs(thread), receiver);
+    if (NS_FAILED(rv)) return rv;
+
+    uint32_t total = 0;
+    for (uint32_t i = 0; i < ITERATIONS; i++) {
+        uint32_t writeCount;
+        char* buf = PR_smprintf("%d %s", i, kTestPattern);
+        uint32_t len = strlen(buf);
+        len = len * rand() / RAND_MAX;
+        len = std::min(1u, len);
+        rv = WriteAll(out, buf, len, &writeCount);
+        if (NS_FAILED(rv)) return rv;
+        EXPECT_EQ(writeCount, len);
+        total += writeCount;
+
+        if (gTrace)
+            printf("wrote %d bytes: %s\n", writeCount, buf);
+        PR_smprintf_free(buf);
+        //printf("calling Flush\n");
+        out->Flush();
+        //printf("calling WaitForReceipt\n");
+
+#ifdef DEBUG
+        const uint32_t received =
+          receiver->WaitForReceipt(writeCount);
+        EXPECT_EQ(received, writeCount);
+#endif
+    }
+    rv = out->Close();
+    if (NS_FAILED(rv)) return rv;
+
+    thread->Shutdown();
+
+    printf("wrote %d bytes\n", total);
+
+    return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+class nsPump final : public nsIRunnable
+{
+public:
+    NS_DECL_THREADSAFE_ISUPPORTS
+
+    NS_IMETHOD Run() override {
+        nsresult rv;
+        uint32_t count;
+        while (true) {
+            rv = mOut->WriteFrom(mIn, ~0U, &count);
+            if (NS_FAILED(rv)) {
+                printf("Write failed\n");
+                break;
+            }
+            if (count == 0) {
+                printf("EOF count = %d\n", mCount);
+                break;
+            }
+
+            if (gTrace) {
+                printf("Wrote: %d\n", count);
+            }
+            mCount += count;
+        }
+        mOut->Close();
+        return rv;
+    }
+
+    nsPump(nsIInputStream* in,
+           nsIOutputStream* out)
+        : mIn(in), mOut(out), mCount(0) {
+    }
+
+private:
+    ~nsPump() {}
+
+protected:
+    nsCOMPtr<nsIInputStream>      mIn;
+    nsCOMPtr<nsIOutputStream>     mOut;
+    uint32_t                            mCount;
+};
+
+NS_IMPL_ISUPPORTS(nsPump, nsIRunnable)
+
+TEST(Pipes, ChainedPipes)
+{
+    nsresult rv;
+    if (gTrace) {
+        printf("TestChainedPipes\n");
+    }
+
+    nsCOMPtr<nsIInputStream> in1;
+    nsCOMPtr<nsIOutputStream> out1;
+    rv = NS_NewPipe(getter_AddRefs(in1), getter_AddRefs(out1), 20, 1999);
+    if (NS_FAILED(rv)) return;
+
+    nsCOMPtr<nsIInputStream> in2;
+    nsCOMPtr<nsIOutputStream> out2;
+    rv = NS_NewPipe(getter_AddRefs(in2), getter_AddRefs(out2), 200, 401);
+    if (NS_FAILED(rv)) return;
+
+    RefPtr<nsPump> pump = new nsPump(in1, out2);
+    if (pump == nullptr) return;
+
+    nsCOMPtr<nsIThread> thread;
+    rv = NS_NewThread(getter_AddRefs(thread), pump);
+    if (NS_FAILED(rv)) return;
+
+    RefPtr<nsReceiver> receiver = new nsReceiver(in2);
+    if (receiver == nullptr) return;
+
+    nsCOMPtr<nsIThread> receiverThread;
+    rv = NS_NewThread(getter_AddRefs(receiverThread), receiver);
+    if (NS_FAILED(rv)) return;
+
+    uint32_t total = 0;
+    for (uint32_t i = 0; i < ITERATIONS; i++) {
+        uint32_t writeCount;
+        char* buf = PR_smprintf("%d %s", i, kTestPattern);
+        uint32_t len = strlen(buf);
+        len = len * rand() / RAND_MAX;
+        len = std::max(1u, len);
+        rv = WriteAll(out1, buf, len, &writeCount);
+        if (NS_FAILED(rv)) return;
+        EXPECT_EQ(writeCount, len);
+        total += writeCount;
+
+        if (gTrace)
+            printf("wrote %d bytes: %s\n", writeCount, buf);
+
+        PR_smprintf_free(buf);
+    }
+    if (gTrace) {
+        printf("wrote total of %d bytes\n", total);
+    }
+    rv = out1->Close();
+    if (NS_FAILED(rv)) return;
+
+    thread->Shutdown();
+    receiverThread->Shutdown();
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+void
+RunTests(uint32_t segSize, uint32_t segCount)
+{
+    nsresult rv;
+    nsCOMPtr<nsIInputStream> in;
+    nsCOMPtr<nsIOutputStream> out;
+    uint32_t bufSize = segSize * segCount;
+    if (gTrace) {
+        printf("Testing New Pipes: segment size %d buffer size %d\n", segSize, bufSize);
+        printf("Testing long writes...\n");
+    }
+    rv = NS_NewPipe(getter_AddRefs(in), getter_AddRefs(out), segSize, bufSize);
+    EXPECT_TRUE(NS_SUCCEEDED(rv));
+    rv = TestPipe(in, out);
+    EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+    if (gTrace) {
+        printf("Testing short writes...\n");
+    }
+    rv = NS_NewPipe(getter_AddRefs(in), getter_AddRefs(out), segSize, bufSize);
+    EXPECT_TRUE(NS_SUCCEEDED(rv));
+    rv = TestShortWrites(in, out);
+    EXPECT_TRUE(NS_SUCCEEDED(rv));
+}
+
+TEST(Pipes, Main)
+{
+    RunTests(16, 1);
+    RunTests(4096, 16);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+namespace {
+
+static const uint32_t DEFAULT_SEGMENT_SIZE = 4 * 1024;
+
+// An alternate pipe testing routing that uses NS_ConsumeStream() instead of
+// manual read loop.
+static void TestPipe2(uint32_t aNumBytes,
+                      uint32_t aSegmentSize = DEFAULT_SEGMENT_SIZE)
+{
+  nsCOMPtr<nsIInputStream> reader;
+  nsCOMPtr<nsIOutputStream> writer;
+
+  uint32_t maxSize = std::max(aNumBytes, aSegmentSize);
+
+  nsresult rv = NS_NewPipe(getter_AddRefs(reader), getter_AddRefs(writer),
+                           aSegmentSize, maxSize);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsTArray<char> inputData;
+  testing::CreateData(aNumBytes, inputData);
+  testing::WriteAllAndClose(writer, inputData);
+  testing::ConsumeAndValidateStream(reader, inputData);
+}
+
+} // namespace
+
+TEST(Pipes, Blocking_32k)
+{
+  TestPipe2(32 * 1024);
+}
+
+TEST(Pipes, Blocking_64k)
+{
+  TestPipe2(64 * 1024);
+}
+
+TEST(Pipes, Blocking_128k)
+{
+  TestPipe2(128 * 1024);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+namespace {
+
+// Utility routine to validate pipe clone before.  There are many knobs.
+//
+// aTotalBytes              Total number of bytes to write to the pipe.
+// aNumWrites               How many separate write calls should be made.  Bytes
+//                          are evenly distributed over these write calls.
+// aNumInitialClones        How many clones of the pipe input stream should be
+//                          made before writing begins.
+// aNumToCloseAfterWrite    How many streams should be closed after each write.
+//                          One stream is always kept open.  This verifies that
+//                          closing one stream does not effect other open
+//                          streams.
+// aNumToCloneAfterWrite    How many clones to create after each write.  Occurs
+//                          after closing any streams.  This tests cloning
+//                          active streams on a pipe that is being written to.
+// aNumStreamToReadPerWrite How many streams to read fully after each write.
+//                          This tests reading cloned streams at different rates
+//                          while the pipe is being written to.
+static void TestPipeClone(uint32_t aTotalBytes,
+                          uint32_t aNumWrites,
+                          uint32_t aNumInitialClones,
+                          uint32_t aNumToCloseAfterWrite,
+                          uint32_t aNumToCloneAfterWrite,
+                          uint32_t aNumStreamsToReadPerWrite,
+                          uint32_t aSegmentSize = DEFAULT_SEGMENT_SIZE)
+{
+  nsCOMPtr<nsIInputStream> reader;
+  nsCOMPtr<nsIOutputStream> writer;
+
+  uint32_t maxSize = std::max(aTotalBytes, aSegmentSize);
+
+  // Use async input streams so we can NS_ConsumeStream() the current data
+  // while the pipe is still being written to.
+  nsresult rv = NS_NewPipe(getter_AddRefs(reader), getter_AddRefs(writer),
+                           aSegmentSize, maxSize,
+                           true, false); // non-blocking - reader, writer
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsICloneableInputStream> cloneable = do_QueryInterface(reader);
+  ASSERT_TRUE(cloneable);
+  ASSERT_TRUE(cloneable->GetCloneable());
+
+  nsTArray<nsCString> outputDataList;
+
+  nsTArray<nsCOMPtr<nsIInputStream>> streamList;
+
+  // first stream is our original reader from the pipe
+  streamList.AppendElement(reader);
+  outputDataList.AppendElement();
+
+  // Clone the initial input stream the specified number of times
+  // before performing any writes.
+  for (uint32_t i = 0; i < aNumInitialClones; ++i) {
+    nsCOMPtr<nsIInputStream>* clone = streamList.AppendElement();
+    rv = cloneable->Clone(getter_AddRefs(*clone));
+    ASSERT_TRUE(NS_SUCCEEDED(rv));
+    ASSERT_TRUE(*clone);
+
+    outputDataList.AppendElement();
+  }
+
+  nsTArray<char> inputData;
+  testing::CreateData(aTotalBytes, inputData);
+
+  const uint32_t bytesPerWrite = ((aTotalBytes - 1)/ aNumWrites) + 1;
+  uint32_t offset = 0;
+  uint32_t remaining = aTotalBytes;
+  uint32_t nextStreamToRead = 0;
+
+  while (remaining) {
+    uint32_t numToWrite = std::min(bytesPerWrite, remaining);
+    testing::Write(writer, inputData, offset, numToWrite);
+    offset += numToWrite;
+    remaining -= numToWrite;
+
+    // Close the specified number of streams.  This allows us to
+    // test that one closed clone does not break other open clones.
+    for (uint32_t i = 0; i < aNumToCloseAfterWrite &&
+                         streamList.Length() > 1; ++i) {
+
+      uint32_t lastIndex = streamList.Length() - 1;
+      streamList[lastIndex]->Close();
+      streamList.RemoveElementAt(lastIndex);
+      outputDataList.RemoveElementAt(lastIndex);
+
+      if (nextStreamToRead >= streamList.Length()) {
+        nextStreamToRead = 0;
+      }
+    }
+
+    // Create the specified number of clones.  This lets us verify
+    // that we can create clones in the middle of pipe reading and
+    // writing.
+    for (uint32_t i = 0; i < aNumToCloneAfterWrite; ++i) {
+      nsCOMPtr<nsIInputStream>* clone = streamList.AppendElement();
+      rv = cloneable->Clone(getter_AddRefs(*clone));
+      ASSERT_TRUE(NS_SUCCEEDED(rv));
+      ASSERT_TRUE(*clone);
+
+      // Initialize the new output data to make whats been read to data for
+      // the original stream.  First stream is always the original stream.
+      nsCString* outputData = outputDataList.AppendElement();
+      *outputData = outputDataList[0];
+    }
+
+    // Read the specified number of streams.  This lets us verify that we
+    // can read from the clones at different rates while the pipe is being
+    // written to.
+    for (uint32_t i = 0; i < aNumStreamsToReadPerWrite; ++i) {
+      nsCOMPtr<nsIInputStream>& stream = streamList[nextStreamToRead];
+      nsCString& outputData = outputDataList[nextStreamToRead];
+
+      // Can't use ConsumeAndValidateStream() here because we're not
+      // guaranteed the exact amount read.  It should just be at least
+      // as many as numToWrite.
+      nsAutoCString tmpOutputData;
+      rv = NS_ConsumeStream(stream, UINT32_MAX, tmpOutputData);
+      ASSERT_TRUE(rv == NS_BASE_STREAM_WOULD_BLOCK || NS_SUCCEEDED(rv));
+      ASSERT_GE(tmpOutputData.Length(), numToWrite);
+
+      outputData += tmpOutputData;
+
+      nextStreamToRead += 1;
+      if (nextStreamToRead >= streamList.Length()) {
+        // Note: When we wrap around on the streams being read, its possible
+        //       we will trigger a segment to be deleted from the pipe.  It
+        //       would be nice to validate this here, but we don't have any
+        //       QI'able interface that would let us check easily.
+
+        nextStreamToRead = 0;
+      }
+    }
+  }
+
+  rv = writer->Close();
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsDependentCSubstring inputString(inputData.Elements(), inputData.Length());
+
+  // Finally, read the remaining bytes from each stream.  This may be
+  // different amounts of data depending on how much reading we did while
+  // writing.  Verify that the end result matches the input data.
+  for (uint32_t i = 0; i < streamList.Length(); ++i) {
+    nsCOMPtr<nsIInputStream>& stream = streamList[i];
+    nsCString& outputData = outputDataList[i];
+
+    nsAutoCString tmpOutputData;
+    rv = NS_ConsumeStream(stream, UINT32_MAX, tmpOutputData);
+    ASSERT_TRUE(rv == NS_BASE_STREAM_WOULD_BLOCK || NS_SUCCEEDED(rv));
+    stream->Close();
+
+    // Append to total amount read from the stream
+    outputData += tmpOutputData;
+
+    ASSERT_EQ(inputString.Length(), outputData.Length());
+    ASSERT_TRUE(inputString.Equals(outputData));
+  }
+}
+
+} // namespace
+
+TEST(Pipes, Clone_BeforeWrite_ReadAtEnd)
+{
+  TestPipeClone(32 * 1024, // total bytes
+                16,        // num writes
+                3,         // num initial clones
+                0,         // num streams to close after each write
+                0,         // num clones to add after each write
+                0);        // num streams to read after each write
+}
+
+TEST(Pipes, Clone_BeforeWrite_ReadDuringWrite)
+{
+  // Since this reads all streams on every write, it should trigger the
+  // pipe cursor roll back optimization.  Currently we can only verify
+  // this with logging.
+
+  TestPipeClone(32 * 1024, // total bytes
+                16,        // num writes
+                3,         // num initial clones
+                0,         // num streams to close after each write
+                0,         // num clones to add after each write
+                4);        // num streams to read after each write
+}
+
+TEST(Pipes, Clone_DuringWrite_ReadAtEnd)
+{
+  TestPipeClone(32 * 1024, // total bytes
+                16,        // num writes
+                0,         // num initial clones
+                0,         // num streams to close after each write
+                1,         // num clones to add after each write
+                0);        // num streams to read after each write
+}
+
+TEST(Pipes, Clone_DuringWrite_ReadDuringWrite)
+{
+  TestPipeClone(32 * 1024, // total bytes
+                16,        // num writes
+                0,         // num initial clones
+                0,         // num streams to close after each write
+                1,         // num clones to add after each write
+                1);        // num streams to read after each write
+}
+
+TEST(Pipes, Clone_DuringWrite_ReadDuringWrite_CloseDuringWrite)
+{
+  // Since this reads streams faster than we clone new ones, it should
+  // trigger pipe segment deletion periodically.  Currently we can
+  // only verify this with logging.
+
+  TestPipeClone(32 * 1024, // total bytes
+                16,        // num writes
+                1,         // num initial clones
+                1,         // num streams to close after each write
+                2,         // num clones to add after each write
+                3);        // num streams to read after each write
+}
+
+TEST(Pipes, Write_AsyncWait)
+{
+  nsCOMPtr<nsIAsyncInputStream> reader;
+  nsCOMPtr<nsIAsyncOutputStream> writer;
+
+  const uint32_t segmentSize = 1024;
+  const uint32_t numSegments = 1;
+
+  nsresult rv = NS_NewPipe2(getter_AddRefs(reader), getter_AddRefs(writer),
+                            true, true,  // non-blocking - reader, writer
+                            segmentSize, numSegments);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsTArray<char> inputData;
+  testing::CreateData(segmentSize, inputData);
+
+  uint32_t numWritten = 0;
+  rv = writer->Write(inputData.Elements(), inputData.Length(), &numWritten);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  rv = writer->Write(inputData.Elements(), inputData.Length(), &numWritten);
+  ASSERT_EQ(NS_BASE_STREAM_WOULD_BLOCK, rv);
+
+  RefPtr<testing::OutputStreamCallback> cb =
+    new testing::OutputStreamCallback();
+
+  rv = writer->AsyncWait(cb, 0, 0, nullptr);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  ASSERT_FALSE(cb->Called());
+
+  testing::ConsumeAndValidateStream(reader, inputData);
+
+  ASSERT_TRUE(cb->Called());
+}
+
+TEST(Pipes, Write_AsyncWait_Clone)
+{
+  nsCOMPtr<nsIAsyncInputStream> reader;
+  nsCOMPtr<nsIAsyncOutputStream> writer;
+
+  const uint32_t segmentSize = 1024;
+  const uint32_t numSegments = 1;
+
+  nsresult rv = NS_NewPipe2(getter_AddRefs(reader), getter_AddRefs(writer),
+                            true, true,  // non-blocking - reader, writer
+                            segmentSize, numSegments);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsIInputStream> clone;
+  rv = NS_CloneInputStream(reader, getter_AddRefs(clone));
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsTArray<char> inputData;
+  testing::CreateData(segmentSize, inputData);
+
+  uint32_t numWritten = 0;
+  rv = writer->Write(inputData.Elements(), inputData.Length(), &numWritten);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  // This attempts to write data beyond the original pipe size limit.  It
+  // should fail since neither side of the clone has been read yet.
+  rv = writer->Write(inputData.Elements(), inputData.Length(), &numWritten);
+  ASSERT_EQ(NS_BASE_STREAM_WOULD_BLOCK, rv);
+
+  RefPtr<testing::OutputStreamCallback> cb =
+    new testing::OutputStreamCallback();
+
+  rv = writer->AsyncWait(cb, 0, 0, nullptr);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  ASSERT_FALSE(cb->Called());
+
+  // Consume data on the original stream, but the clone still has not been read.
+  testing::ConsumeAndValidateStream(reader, inputData);
+
+  // A clone that is not being read should not stall the other input stream
+  // reader.  Therefore the writer callback should trigger when the fastest
+  // reader drains the other input stream.
+  ASSERT_TRUE(cb->Called());
+
+  // Attempt to write data.  This will buffer data beyond the pipe size limit in
+  // order for the clone stream to still work.  This is allowed because the
+  // other input stream has drained its buffered segments and is ready for more
+  // data.
+  rv = writer->Write(inputData.Elements(), inputData.Length(), &numWritten);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  // Again, this should fail since the origin stream has not been read again.
+  // The pipe size should still restrict how far ahead we can buffer even
+  // when there is a cloned stream not being read.
+  rv = writer->Write(inputData.Elements(), inputData.Length(), &numWritten);
+  ASSERT_TRUE(NS_FAILED(rv));
+
+  cb = new testing::OutputStreamCallback();
+  rv = writer->AsyncWait(cb, 0, 0, nullptr);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  // The write should again be blocked since we have written data and the
+  // main reader is at its maximum advance buffer.
+  ASSERT_FALSE(cb->Called());
+
+  nsTArray<char> expectedCloneData;
+  expectedCloneData.AppendElements(inputData);
+  expectedCloneData.AppendElements(inputData);
+
+  // We should now be able to consume the entire backlog of buffered data on
+  // the cloned stream.
+  testing::ConsumeAndValidateStream(clone, expectedCloneData);
+
+  // Draining the clone side should also trigger the AsyncWait() writer
+  // callback
+  ASSERT_TRUE(cb->Called());
+
+  // Finally, we should be able to consume the remaining data on the original
+  // reader.
+  testing::ConsumeAndValidateStream(reader, inputData);
+}
+
+TEST(Pipes, Write_AsyncWait_Clone_CloseOriginal)
+{
+  nsCOMPtr<nsIAsyncInputStream> reader;
+  nsCOMPtr<nsIAsyncOutputStream> writer;
+
+  const uint32_t segmentSize = 1024;
+  const uint32_t numSegments = 1;
+
+  nsresult rv = NS_NewPipe2(getter_AddRefs(reader), getter_AddRefs(writer),
+                            true, true,  // non-blocking - reader, writer
+                            segmentSize, numSegments);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsIInputStream> clone;
+  rv = NS_CloneInputStream(reader, getter_AddRefs(clone));
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsTArray<char> inputData;
+  testing::CreateData(segmentSize, inputData);
+
+  uint32_t numWritten = 0;
+  rv = writer->Write(inputData.Elements(), inputData.Length(), &numWritten);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  // This attempts to write data beyond the original pipe size limit.  It
+  // should fail since neither side of the clone has been read yet.
+  rv = writer->Write(inputData.Elements(), inputData.Length(), &numWritten);
+  ASSERT_EQ(NS_BASE_STREAM_WOULD_BLOCK, rv);
+
+  RefPtr<testing::OutputStreamCallback> cb =
+    new testing::OutputStreamCallback();
+
+  rv = writer->AsyncWait(cb, 0, 0, nullptr);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  ASSERT_FALSE(cb->Called());
+
+  // Consume data on the original stream, but the clone still has not been read.
+  testing::ConsumeAndValidateStream(reader, inputData);
+
+  // A clone that is not being read should not stall the other input stream
+  // reader.  Therefore the writer callback should trigger when the fastest
+  // reader drains the other input stream.
+  ASSERT_TRUE(cb->Called());
+
+  // Attempt to write data.  This will buffer data beyond the pipe size limit in
+  // order for the clone stream to still work.  This is allowed because the
+  // other input stream has drained its buffered segments and is ready for more
+  // data.
+  rv = writer->Write(inputData.Elements(), inputData.Length(), &numWritten);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  // Again, this should fail since the origin stream has not been read again.
+  // The pipe size should still restrict how far ahead we can buffer even
+  // when there is a cloned stream not being read.
+  rv = writer->Write(inputData.Elements(), inputData.Length(), &numWritten);
+  ASSERT_TRUE(NS_FAILED(rv));
+
+  cb = new testing::OutputStreamCallback();
+  rv = writer->AsyncWait(cb, 0, 0, nullptr);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  // The write should again be blocked since we have written data and the
+  // main reader is at its maximum advance buffer.
+  ASSERT_FALSE(cb->Called());
+
+  // Close the original reader input stream.  This was the fastest reader,
+  // so we should have a single stream that is buffered beyond our nominal
+  // limit.
+  reader->Close();
+
+  // Because the clone stream is still buffered the writable callback should
+  // not be fired.
+  ASSERT_FALSE(cb->Called());
+
+  // And we should not be able to perform a write.
+  rv = writer->Write(inputData.Elements(), inputData.Length(), &numWritten);
+  ASSERT_TRUE(NS_FAILED(rv));
+
+  // Create another clone stream.  Now we have two streams that exceed our
+  // maximum size limit
+  nsCOMPtr<nsIInputStream> clone2;
+  rv = NS_CloneInputStream(clone, getter_AddRefs(clone2));
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsTArray<char> expectedCloneData;
+  expectedCloneData.AppendElements(inputData);
+  expectedCloneData.AppendElements(inputData);
+
+  // We should now be able to consume the entire backlog of buffered data on
+  // the cloned stream.
+  testing::ConsumeAndValidateStream(clone, expectedCloneData);
+
+  // The pipe should now be writable because we have two open streams, one of which
+  // is completely drained.
+  ASSERT_TRUE(cb->Called());
+
+  // Write again to reach our limit again.
+  rv = writer->Write(inputData.Elements(), inputData.Length(), &numWritten);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  // The stream is again non-writeable.
+  cb = new testing::OutputStreamCallback();
+  rv = writer->AsyncWait(cb, 0, 0, nullptr);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+  ASSERT_FALSE(cb->Called());
+
+  // Close the empty stream.  This is different from our previous close since
+  // before we were closing a stream with some data still buffered.
+  clone->Close();
+
+  // The pipe should not be writable.  The second clone is still fully buffered
+  // over our limit.
+  ASSERT_FALSE(cb->Called());
+  rv = writer->Write(inputData.Elements(), inputData.Length(), &numWritten);
+  ASSERT_TRUE(NS_FAILED(rv));
+
+  // Finally consume all of the buffered data on the second clone.
+  expectedCloneData.AppendElements(inputData);
+  testing::ConsumeAndValidateStream(clone2, expectedCloneData);
+
+  // Draining the final clone should make the pipe writable again.
+  ASSERT_TRUE(cb->Called());
+}
+
+TEST(Pipes, Read_AsyncWait)
+{
+  nsCOMPtr<nsIAsyncInputStream> reader;
+  nsCOMPtr<nsIAsyncOutputStream> writer;
+
+  const uint32_t segmentSize = 1024;
+  const uint32_t numSegments = 1;
+
+  nsresult rv = NS_NewPipe2(getter_AddRefs(reader), getter_AddRefs(writer),
+                            true, true,  // non-blocking - reader, writer
+                            segmentSize, numSegments);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsTArray<char> inputData;
+  testing::CreateData(segmentSize, inputData);
+
+  RefPtr<testing::InputStreamCallback> cb =
+    new testing::InputStreamCallback();
+
+  rv = reader->AsyncWait(cb, 0, 0, nullptr);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  ASSERT_FALSE(cb->Called());
+
+  uint32_t numWritten = 0;
+  rv = writer->Write(inputData.Elements(), inputData.Length(), &numWritten);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  ASSERT_TRUE(cb->Called());
+
+  testing::ConsumeAndValidateStream(reader, inputData);
+}
+
+TEST(Pipes, Read_AsyncWait_Clone)
+{
+  nsCOMPtr<nsIAsyncInputStream> reader;
+  nsCOMPtr<nsIAsyncOutputStream> writer;
+
+  const uint32_t segmentSize = 1024;
+  const uint32_t numSegments = 1;
+
+  nsresult rv = NS_NewPipe2(getter_AddRefs(reader), getter_AddRefs(writer),
+                            true, true,  // non-blocking - reader, writer
+                            segmentSize, numSegments);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsIInputStream> clone;
+  rv = NS_CloneInputStream(reader, getter_AddRefs(clone));
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsIAsyncInputStream> asyncClone = do_QueryInterface(clone);
+  ASSERT_TRUE(asyncClone);
+
+  nsTArray<char> inputData;
+  testing::CreateData(segmentSize, inputData);
+
+  RefPtr<testing::InputStreamCallback> cb =
+    new testing::InputStreamCallback();
+
+  RefPtr<testing::InputStreamCallback> cb2 =
+    new testing::InputStreamCallback();
+
+  rv = reader->AsyncWait(cb, 0, 0, nullptr);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  ASSERT_FALSE(cb->Called());
+
+  rv = asyncClone->AsyncWait(cb2, 0, 0, nullptr);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  ASSERT_FALSE(cb2->Called());
+
+  uint32_t numWritten = 0;
+  rv = writer->Write(inputData.Elements(), inputData.Length(), &numWritten);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  ASSERT_TRUE(cb->Called());
+  ASSERT_TRUE(cb2->Called());
+
+  testing::ConsumeAndValidateStream(reader, inputData);
+}
+
+namespace {
+
+nsresult
+CloseDuringReadFunc(nsIInputStream *aReader,
+                    void* aClosure,
+                    const char* aFromSegment,
+                    uint32_t aToOffset,
+                    uint32_t aCount,
+                    uint32_t* aWriteCountOut)
+{
+  MOZ_RELEASE_ASSERT(aReader);
+  MOZ_RELEASE_ASSERT(aClosure);
+  MOZ_RELEASE_ASSERT(aFromSegment);
+  MOZ_RELEASE_ASSERT(aWriteCountOut);
+  MOZ_RELEASE_ASSERT(aToOffset == 0);
+
+  // This is insanity and you probably should not do this under normal
+  // conditions.  We want to simulate the case where the pipe is closed
+  // (possibly from other end on another thread) simultaneously with the
+  // read.  This is the easiest way to do trigger this case in a synchronous
+  // gtest.
+  MOZ_ALWAYS_SUCCEEDS(aReader->Close());
+
+  nsTArray<char>* buffer = static_cast<nsTArray<char>*>(aClosure);
+  buffer->AppendElements(aFromSegment, aCount);
+
+  *aWriteCountOut = aCount;
+
+  return NS_OK;
+}
+
+void
+TestCloseDuringRead(uint32_t aSegmentSize, uint32_t aDataSize)
+{
+  nsCOMPtr<nsIInputStream> reader;
+  nsCOMPtr<nsIOutputStream> writer;
+
+  const uint32_t maxSize = aSegmentSize;
+
+  nsresult rv = NS_NewPipe(getter_AddRefs(reader), getter_AddRefs(writer),
+                           aSegmentSize, maxSize);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsTArray<char> inputData;
+
+  testing::CreateData(aDataSize, inputData);
+
+  uint32_t numWritten = 0;
+  rv = writer->Write(inputData.Elements(), inputData.Length(), &numWritten);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsTArray<char> outputData;
+
+  uint32_t numRead = 0;
+  rv = reader->ReadSegments(CloseDuringReadFunc, &outputData,
+                            inputData.Length(), &numRead);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+  ASSERT_EQ(inputData.Length(), numRead);
+
+  ASSERT_EQ(inputData, outputData);
+
+  uint64_t available;
+  rv = reader->Available(&available);
+  ASSERT_EQ(NS_BASE_STREAM_CLOSED, rv);
+}
+
+} // namespace
+
+TEST(Pipes, Close_During_Read_Partial_Segment)
+{
+  TestCloseDuringRead(1024, 512);
+}
+
+TEST(Pipes, Close_During_Read_Full_Segment)
+{
+  TestCloseDuringRead(1024, 1024);
+}
+
+TEST(Pipes, Interfaces)
+{
+  nsCOMPtr<nsIInputStream> reader;
+  nsCOMPtr<nsIOutputStream> writer;
+
+  nsresult rv = NS_NewPipe(getter_AddRefs(reader), getter_AddRefs(writer));
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsIAsyncInputStream> readerType1 = do_QueryInterface(reader);
+  ASSERT_TRUE(readerType1);
+
+  nsCOMPtr<nsISeekableStream> readerType2 = do_QueryInterface(reader);
+  ASSERT_TRUE(readerType2);
+
+  nsCOMPtr<nsISearchableInputStream> readerType3 = do_QueryInterface(reader);
+  ASSERT_TRUE(readerType3);
+
+  nsCOMPtr<nsICloneableInputStream> readerType4 = do_QueryInterface(reader);
+  ASSERT_TRUE(readerType4);
+
+  nsCOMPtr<nsIClassInfo> readerType5 = do_QueryInterface(reader);
+  ASSERT_TRUE(readerType5);
+
+  nsCOMPtr<nsIBufferedInputStream> readerType6 = do_QueryInterface(reader);
+  ASSERT_TRUE(readerType6);
+}
diff --git a/xpcom/tests/gtest/TestPriorityQueue.cpp b/xpcom/tests/gtest/TestPriorityQueue.cpp
new file mode 100644
index 000000000..eeb2f1e09
--- /dev/null
+++ b/xpcom/tests/gtest/TestPriorityQueue.cpp
@@ -0,0 +1,76 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsTPriorityQueue.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include "gtest/gtest.h"
+
+template<class T, class Compare>
+void
+CheckPopSequence(const nsTPriorityQueue<T, Compare>& aQueue,
+                 const T* aExpectedSequence, const uint32_t aSequenceLength)
+{
+  nsTPriorityQueue<T, Compare> copy(aQueue);
+
+  for (uint32_t i = 0; i < aSequenceLength; i++) {
+    EXPECT_FALSE(copy.IsEmpty());
+
+    T pop = copy.Pop();
+    EXPECT_EQ(pop, aExpectedSequence[i]);
+  }
+
+  EXPECT_TRUE(copy.IsEmpty());
+}
+
+template<class A>
+class MaxCompare {
+public:
+  bool LessThan(const A& a, const A& b) {
+    return a > b;
+  }
+};
+
+TEST(PriorityQueue, Main)
+{
+  nsTPriorityQueue<int> queue;
+
+  EXPECT_TRUE(queue.IsEmpty());
+
+  queue.Push(8);
+  queue.Push(6);
+  queue.Push(4);
+  queue.Push(2);
+  queue.Push(10);
+  queue.Push(6);
+  EXPECT_EQ(queue.Top(), 2);
+  EXPECT_EQ(queue.Length(), 6u);
+  EXPECT_FALSE(queue.IsEmpty());
+  int expected[] = { 2, 4, 6, 6, 8, 10 };
+  CheckPopSequence(queue, expected, sizeof(expected) / sizeof(expected[0]));
+
+  // copy ctor is tested by using CheckPopSequence, but check default assignment
+  // operator
+  nsTPriorityQueue<int> queue2;
+  queue2 = queue;
+  CheckPopSequence(queue2, expected, sizeof(expected) / sizeof(expected[0]));
+
+  queue.Clear();
+  EXPECT_TRUE(queue.IsEmpty());
+
+  // try same sequence with a max heap
+  nsTPriorityQueue<int, MaxCompare<int> > max_queue;
+  max_queue.Push(8);
+  max_queue.Push(6);
+  max_queue.Push(4);
+  max_queue.Push(2);
+  max_queue.Push(10);
+  max_queue.Push(6);
+  EXPECT_EQ(max_queue.Top(), 10);
+  int expected_max[] = { 10, 8, 6, 6, 4, 2 };
+  CheckPopSequence(max_queue, expected_max,
+      sizeof(expected_max) / sizeof(expected_max[0]));
+}
diff --git a/xpcom/tests/gtest/TestRacingServiceManager.cpp b/xpcom/tests/gtest/TestRacingServiceManager.cpp
new file mode 100644
index 000000000..b0638db02
--- /dev/null
+++ b/xpcom/tests/gtest/TestRacingServiceManager.cpp
@@ -0,0 +1,300 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIFactory.h"
+#include "mozilla/Module.h"
+#include "nsXULAppAPI.h"
+#include "nsIThread.h"
+#include "nsIComponentRegistrar.h"
+
+#include "nsAutoPtr.h"
+#include "nsThreadUtils.h"
+#include "nsXPCOMCIDInternal.h"
+#include "pratom.h"
+#include "prmon.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+
+#include "mozilla/ReentrantMonitor.h"
+
+#include "gtest/gtest.h"
+
+using namespace mozilla;
+
+/* f93f6bdc-88af-42d7-9d64-1b43c649a3e5 */ 
+#define FACTORY_CID1                                 \
+{                                                    \
+  0xf93f6bdc,                                        \
+  0x88af,                                            \
+  0x42d7,                                            \
+  { 0x9d, 0x64, 0x1b, 0x43, 0xc6, 0x49, 0xa3, 0xe5 } \
+}
+NS_DEFINE_CID(kFactoryCID1, FACTORY_CID1);
+
+/* ef38ad65-6595-49f0-8048-e819f81d15e2 */
+#define FACTORY_CID2                                 \
+{                                                    \
+  0xef38ad65,                                        \
+  0x6595,                                            \
+  0x49f0,                                            \
+  { 0x80, 0x48, 0xe8, 0x19, 0xf8, 0x1d, 0x15, 0xe2 } \
+}
+NS_DEFINE_CID(kFactoryCID2, FACTORY_CID2);
+
+#define FACTORY_CONTRACTID                           \
+  "TestRacingThreadManager/factory;1"
+
+namespace TestRacingServiceManager
+{
+int32_t gComponent1Count = 0;
+int32_t gComponent2Count = 0;
+
+ReentrantMonitor* gReentrantMonitor = nullptr;
+
+bool gCreateInstanceCalled = false;
+bool gMainThreadWaiting = false;
+
+class AutoCreateAndDestroyReentrantMonitor
+{
+public:
+  explicit AutoCreateAndDestroyReentrantMonitor(ReentrantMonitor** aReentrantMonitorPtr)
+  : mReentrantMonitorPtr(aReentrantMonitorPtr) {
+    *aReentrantMonitorPtr =
+      new ReentrantMonitor("TestRacingServiceManager::AutoMon");
+    MOZ_RELEASE_ASSERT(*aReentrantMonitorPtr, "Out of memory!");
+  }
+
+  ~AutoCreateAndDestroyReentrantMonitor() {
+    if (*mReentrantMonitorPtr) {
+      delete *mReentrantMonitorPtr;
+      *mReentrantMonitorPtr = nullptr;
+    }
+  }
+
+private:
+  ReentrantMonitor** mReentrantMonitorPtr;
+};
+
+class Factory final : public nsIFactory
+{
+  ~Factory() {}
+
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  Factory() : mFirstComponentCreated(false) { }
+
+  NS_IMETHOD CreateInstance(nsISupports* aDelegate,
+                            const nsIID& aIID,
+                            void** aResult) override;
+
+  NS_IMETHOD LockFactory(bool aLock) override {
+    return NS_OK;
+  }
+
+  bool mFirstComponentCreated;
+};
+
+NS_IMPL_ISUPPORTS(Factory, nsIFactory)
+
+class Component1 final : public nsISupports
+{
+  ~Component1() {}
+
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  Component1() {
+    // This is the real test - make sure that only one instance is ever created.
+    int32_t count = PR_AtomicIncrement(&gComponent1Count);
+    MOZ_RELEASE_ASSERT(count == 1, "Too many components created!");
+  }
+};
+
+NS_IMPL_ADDREF(Component1)
+NS_IMPL_RELEASE(Component1)
+
+NS_INTERFACE_MAP_BEGIN(Component1)
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+class Component2 final : public nsISupports
+{
+  ~Component2() {}
+
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  Component2() {
+    // This is the real test - make sure that only one instance is ever created.
+    int32_t count = PR_AtomicIncrement(&gComponent2Count);
+    EXPECT_EQ(count, int32_t(1)) << "Too many components created!";
+  }
+};
+
+NS_IMPL_ADDREF(Component2)
+NS_IMPL_RELEASE(Component2)
+
+NS_INTERFACE_MAP_BEGIN(Component2)
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+NS_IMETHODIMP
+Factory::CreateInstance(nsISupports* aDelegate,
+                        const nsIID& aIID,
+                        void** aResult)
+{
+  // Make sure that the second thread beat the main thread to the getService
+  // call.
+  MOZ_RELEASE_ASSERT(!NS_IsMainThread(), "Wrong thread!");
+
+  {
+    ReentrantMonitorAutoEnter mon(*gReentrantMonitor);
+
+    gCreateInstanceCalled = true;
+    mon.Notify();
+
+    mon.Wait(PR_MillisecondsToInterval(3000));
+  }
+
+  NS_ENSURE_FALSE(aDelegate, NS_ERROR_NO_AGGREGATION);
+  NS_ENSURE_ARG_POINTER(aResult);
+
+  nsCOMPtr<nsISupports> instance;
+
+  if (!mFirstComponentCreated) {
+    instance = new Component1();
+  }
+  else {
+    instance = new Component2();
+  }
+  NS_ENSURE_TRUE(instance, NS_ERROR_OUT_OF_MEMORY);
+
+  nsresult rv = instance->QueryInterface(aIID, aResult);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return NS_OK;
+}
+
+class TestRunnable : public Runnable
+{
+public:
+  NS_DECL_NSIRUNNABLE
+
+  TestRunnable() : mFirstRunnableDone(false) { }
+
+  bool mFirstRunnableDone;
+};
+
+NS_IMETHODIMP
+TestRunnable::Run()
+{
+  {
+    ReentrantMonitorAutoEnter mon(*gReentrantMonitor);
+
+    while (!gMainThreadWaiting) {
+      mon.Wait();
+    }
+  }
+
+  nsresult rv;
+  nsCOMPtr<nsISupports> component;
+
+  if (!mFirstRunnableDone) {
+    component = do_GetService(kFactoryCID1, &rv);
+  }
+  else {
+    component = do_GetService(FACTORY_CONTRACTID, &rv);
+  }
+  EXPECT_TRUE(NS_SUCCEEDED(rv)) << "GetService failed!";
+
+  return NS_OK;
+}
+
+static Factory* gFactory;
+
+static already_AddRefed<nsIFactory>
+CreateFactory(const mozilla::Module& module, const mozilla::Module::CIDEntry& entry)
+{
+    if (!gFactory) {
+        gFactory = new Factory();
+        NS_ADDREF(gFactory);
+    }
+    nsCOMPtr<nsIFactory> ret = gFactory;
+    return ret.forget();
+}
+
+static const mozilla::Module::CIDEntry kLocalCIDs[] = {
+    { &kFactoryCID1, false, CreateFactory, nullptr },
+    { &kFactoryCID2, false, CreateFactory, nullptr },
+    { nullptr }
+};
+
+static const mozilla::Module::ContractIDEntry kLocalContracts[] = {
+    { FACTORY_CONTRACTID, &kFactoryCID2 },
+    { nullptr }
+};
+
+static const mozilla::Module kLocalModule = {
+    mozilla::Module::kVersion,
+    kLocalCIDs,
+    kLocalContracts
+};
+
+TEST(RacingServiceManager, Test)
+{
+  nsresult rv;
+  XRE_AddStaticComponent(&kLocalModule);
+
+  AutoCreateAndDestroyReentrantMonitor mon1(&gReentrantMonitor);
+
+  RefPtr<TestRunnable> runnable = new TestRunnable();
+  ASSERT_TRUE(runnable);
+
+  // Run the classID test
+  nsCOMPtr<nsIThread> newThread;
+  rv = NS_NewThread(getter_AddRefs(newThread), runnable);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  {
+    ReentrantMonitorAutoEnter mon2(*gReentrantMonitor);
+
+    gMainThreadWaiting = true;
+    mon2.Notify();
+
+    while (!gCreateInstanceCalled) {
+      mon2.Wait();
+    }
+  }
+
+  nsCOMPtr<nsISupports> component(do_GetService(kFactoryCID1, &rv));
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  // Reset for the contractID test
+  gMainThreadWaiting = gCreateInstanceCalled = false;
+  gFactory->mFirstComponentCreated = runnable->mFirstRunnableDone = true;
+  component = nullptr;
+
+  rv = newThread->Dispatch(runnable, NS_DISPATCH_NORMAL);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  {
+    ReentrantMonitorAutoEnter mon3(*gReentrantMonitor);
+
+    gMainThreadWaiting = true;
+    mon3.Notify();
+
+    while (!gCreateInstanceCalled) {
+      mon3.Wait();
+    }
+  }
+
+  component = do_GetService(FACTORY_CONTRACTID, &rv);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  NS_RELEASE(gFactory);
+}
+
+} // namespace TestRacingServiceManager
diff --git a/xpcom/tests/gtest/TestSTLWrappers.cpp b/xpcom/tests/gtest/TestSTLWrappers.cpp
new file mode 100644
index 000000000..9559548a3
--- /dev/null
+++ b/xpcom/tests/gtest/TestSTLWrappers.cpp
@@ -0,0 +1,78 @@
+#include <stdio.h>
+
+#include <algorithm>
+#ifndef mozilla_algorithm_h
+#  error "failed to wrap <algorithm>"
+#endif
+
+#include <vector>
+#ifndef mozilla_vector_h
+#  error "failed to wrap <vector>"
+#endif
+
+#ifdef MOZ_CRASHREPORTER
+#include "nsCOMPtr.h"
+#include "nsICrashReporter.h"
+#include "nsServiceManagerUtils.h"
+#endif
+
+// gcc errors out if we |try ... catch| with -fno-exceptions, but we
+// can still test on windows
+#ifdef _MSC_VER
+   // C4530 will be generated whenever try...catch is used without
+   // enabling exceptions. We know we don't enbale exceptions.
+#  pragma warning( disable : 4530 )
+#  define TRY       try
+#  define CATCH(e)  catch (e)
+#else
+#  define TRY
+#  define CATCH(e)  if (0)
+#endif
+
+
+#if defined(XP_UNIX)
+extern unsigned int _gdb_sleep_duration;
+#endif
+
+void ShouldAbort()
+{
+#if defined(XP_UNIX)
+    _gdb_sleep_duration = 0;
+#endif
+
+#ifdef MOZ_CRASHREPORTER
+    nsCOMPtr<nsICrashReporter> crashreporter =
+        do_GetService("@mozilla.org/toolkit/crash-reporter;1");
+    if (crashreporter) {
+      crashreporter->SetEnabled(false);
+    }
+#endif
+
+    std::vector<int> v;
+    int rv = 1;
+
+    TRY {
+      // v.at(1) on empty v should abort; NOT throw an exception
+
+      // (Do some arithmetic with result of v.at() to avoid
+      // compiler warnings for unused variable/result.)
+      rv += v.at(1) ? 1 : 2;
+    } CATCH(const std::out_of_range&) {
+      fputs("TEST-FAIL | TestSTLWrappers.cpp | caught an exception?\n",
+            stderr);
+      return;
+    }
+
+    fputs("TEST-FAIL | TestSTLWrappers.cpp | didn't abort()?\n",
+          stderr);
+    return;
+}
+
+#ifdef XP_WIN
+TEST(STLWrapper, DISABLED_ShouldAbortDeathTest)
+#else
+TEST(STLWrapper, ShouldAbortDeathTest)
+#endif
+{
+  ASSERT_DEATH_IF_SUPPORTED(ShouldAbort(), "terminate called after throwing an instance of 'std::out_of_range'|vector::_M_range_check");
+}
diff --git a/xpcom/tests/gtest/TestSlicedInputStream.cpp b/xpcom/tests/gtest/TestSlicedInputStream.cpp
new file mode 100644
index 000000000..ccad0a6a8
--- /dev/null
+++ b/xpcom/tests/gtest/TestSlicedInputStream.cpp
@@ -0,0 +1,266 @@
+#include "gtest/gtest.h"
+
+#include "nsCOMPtr.h"
+#include "nsIInputStream.h"
+#include "nsStreamUtils.h"
+#include "nsString.h"
+#include "nsStringStream.h"
+#include "SlicedInputStream.h"
+
+/* We want to ensure that sliced streams work with both seekable and
+ * non-seekable input streams.  As our string streams are seekable, we need to
+ * provide a string stream that doesn't permit seeking, so we can test the
+ * logic that emulates seeking in sliced input streams.
+ */
+class NonSeekableStringStream final : public nsIInputStream
+{
+  nsCOMPtr<nsIInputStream> mStream;
+
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  explicit NonSeekableStringStream(const nsACString& aBuffer)
+  {
+    NS_NewCStringInputStream(getter_AddRefs(mStream), aBuffer);
+  }
+
+  NS_IMETHOD
+  Available(uint64_t* aLength) override
+  {
+    return mStream->Available(aLength);
+  }
+
+  NS_IMETHOD
+  Read(char* aBuffer, uint32_t aCount, uint32_t* aReadCount) override
+  {
+    return mStream->Read(aBuffer, aCount, aReadCount);
+  }
+
+  NS_IMETHOD
+  ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
+               uint32_t aCount, uint32_t *aResult) override
+  {
+    return mStream->ReadSegments(aWriter, aClosure, aCount, aResult);
+  }
+
+  NS_IMETHOD
+  Close() override
+  {
+    return mStream->Close();
+  }
+
+  NS_IMETHOD
+  IsNonBlocking(bool* aNonBlocking) override
+  {
+    return mStream->IsNonBlocking(aNonBlocking);
+  }
+
+private:
+  ~NonSeekableStringStream() {}
+};
+
+NS_IMPL_ISUPPORTS(NonSeekableStringStream, nsIInputStream)
+
+// Helper function for creating a seekable nsIInputStream + a SlicedInputStream.
+SlicedInputStream*
+CreateSeekableStreams(uint32_t aSize, uint64_t aStart, uint64_t aLength,
+                      nsCString& aBuffer)
+{
+  aBuffer.SetLength(aSize);
+  for (uint32_t i = 0; i < aSize; ++i) {
+    aBuffer.BeginWriting()[i] = i % 10;
+  }
+
+  nsCOMPtr<nsIInputStream> stream;
+  NS_NewCStringInputStream(getter_AddRefs(stream), aBuffer);
+  return new SlicedInputStream(stream, aStart, aLength);
+}
+
+// Helper function for creating a non-seekable nsIInputStream + a
+// SlicedInputStream.
+SlicedInputStream*
+CreateNonSeekableStreams(uint32_t aSize, uint64_t aStart, uint64_t aLength,
+                         nsCString& aBuffer)
+{
+  aBuffer.SetLength(aSize);
+  for (uint32_t i = 0; i < aSize; ++i) {
+    aBuffer.BeginWriting()[i] = i % 10;
+  }
+
+  RefPtr<NonSeekableStringStream> stream = new NonSeekableStringStream(aBuffer);
+  return new SlicedInputStream(stream, aStart, aLength);
+}
+
+// Same start, same length.
+TEST(TestSlicedInputStream, Simple) {
+  const size_t kBufSize = 4096;
+
+  nsCString buf;
+  RefPtr<SlicedInputStream> sis =
+    CreateSeekableStreams(kBufSize, 0, kBufSize, buf);
+
+  uint64_t length;
+  ASSERT_EQ(NS_OK, sis->Available(&length));
+  ASSERT_EQ((uint64_t)kBufSize, length);
+
+  char buf2[kBufSize];
+  uint32_t count;
+  ASSERT_EQ(NS_OK, sis->Read(buf2, sizeof(buf2), &count));
+  ASSERT_EQ(count, buf.Length());
+  ASSERT_TRUE(nsCString(buf.get()).Equals(nsCString(buf2)));
+}
+
+// Simple sliced stream - seekable
+TEST(TestSlicedInputStream, Sliced) {
+  const size_t kBufSize = 4096;
+
+  nsCString buf;
+  RefPtr<SlicedInputStream> sis =
+    CreateSeekableStreams(kBufSize, 10, 100, buf);
+
+  uint64_t length;
+  ASSERT_EQ(NS_OK, sis->Available(&length));
+  ASSERT_EQ((uint64_t)100, length);
+
+  char buf2[kBufSize / 2];
+  uint32_t count;
+  ASSERT_EQ(NS_OK, sis->Read(buf2, sizeof(buf2), &count));
+  ASSERT_EQ((uint64_t)100, count);
+  ASSERT_TRUE(nsCString(buf.get() + 10, count).Equals(nsCString(buf2, count)));
+}
+
+// Simple sliced stream - non seekable
+TEST(TestSlicedInputStream, SlicedNoSeek) {
+  const size_t kBufSize = 4096;
+
+  nsCString buf;
+  RefPtr<SlicedInputStream> sis =
+    CreateNonSeekableStreams(kBufSize, 10, 100, buf);
+
+  uint64_t length;
+  ASSERT_EQ(NS_OK, sis->Available(&length));
+  ASSERT_EQ((uint64_t)100, length);
+
+  char buf2[kBufSize / 2];
+  uint32_t count;
+  ASSERT_EQ(NS_OK, sis->Read(buf2, sizeof(buf2), &count));
+  ASSERT_EQ((uint64_t)100, count);
+  ASSERT_TRUE(nsCString(buf.get() + 10, count).Equals(nsCString(buf2, count)));
+}
+
+// Big inputStream - seekable
+TEST(TestSlicedInputStream, BigSliced) {
+  const size_t kBufSize = 4096 * 40;
+
+  nsCString buf;
+  RefPtr<SlicedInputStream> sis =
+    CreateSeekableStreams(kBufSize, 4096 * 5, 4096 * 10, buf);
+
+  uint64_t length;
+  ASSERT_EQ(NS_OK, sis->Available(&length));
+  ASSERT_EQ((uint64_t)4096 * 10, length);
+
+  char buf2[kBufSize / 2];
+  uint32_t count;
+  ASSERT_EQ(NS_OK, sis->Read(buf2, sizeof(buf2), &count));
+  ASSERT_EQ((uint64_t)4096 * 10, count);
+  ASSERT_TRUE(nsCString(buf.get() + 4096 * 5, count).Equals(nsCString(buf2, count)));
+}
+
+// Big inputStream - non seekable
+TEST(TestSlicedInputStream, BigSlicedNoSeek) {
+  const size_t kBufSize = 4096 * 40;
+
+  nsCString buf;
+  RefPtr<SlicedInputStream> sis =
+    CreateNonSeekableStreams(kBufSize, 4096 * 5, 4096 * 10, buf);
+
+  uint64_t length;
+  ASSERT_EQ(NS_OK, sis->Available(&length));
+  ASSERT_EQ((uint64_t)4096 * 10, length);
+
+  char buf2[kBufSize / 2];
+  uint32_t count;
+  ASSERT_EQ(NS_OK, sis->Read(buf2, sizeof(buf2), &count));
+  ASSERT_EQ((uint64_t)4096 * 10, count);
+  ASSERT_TRUE(nsCString(buf.get() + 4096 * 5, count).Equals(nsCString(buf2, count)));
+}
+
+// Available size.
+TEST(TestSlicedInputStream, Available) {
+  nsCString buf;
+  RefPtr<SlicedInputStream> sis =
+    CreateNonSeekableStreams(500000, 4, 400000, buf);
+
+  uint64_t toRead = 400000;
+  for (uint32_t i = 0; i < 400; ++i) {
+    uint64_t length;
+    ASSERT_EQ(NS_OK, sis->Available(&length));
+    ASSERT_EQ(toRead, length);
+
+    char buf2[1000];
+    uint32_t count;
+    ASSERT_EQ(NS_OK, sis->Read(buf2, sizeof(buf2), &count));
+    ASSERT_EQ((uint64_t)1000, count);
+    ASSERT_TRUE(nsCString(buf.get() + 4 + (1000 * i), count).Equals(nsCString(buf2, count)));
+
+    toRead -= count;
+  }
+
+  uint64_t length;
+  ASSERT_EQ(NS_OK, sis->Available(&length));
+  ASSERT_EQ((uint64_t)0, length);
+
+  char buf2[4096];
+  uint32_t count;
+  ASSERT_EQ(NS_OK, sis->Read(buf2, sizeof(buf2), &count));
+  ASSERT_EQ((uint64_t)0, count);
+}
+
+// What if start is > then the size of the buffer?
+TEST(TestSlicedInputStream, StartBiggerThan) {
+  nsCString buf;
+  RefPtr<SlicedInputStream> sis =
+    CreateNonSeekableStreams(500, 4000, 1, buf);
+
+  uint64_t length;
+  ASSERT_EQ(NS_OK, sis->Available(&length));
+  ASSERT_EQ((uint64_t)0, length);
+
+  char buf2[4096];
+  uint32_t count;
+  ASSERT_EQ(NS_OK, sis->Read(buf2, sizeof(buf2), &count));
+  ASSERT_EQ((uint64_t)0, count);
+}
+
+// What if the length is > than the size of the buffer?
+TEST(TestSlicedInputStream, LengthBiggerThan) {
+  nsCString buf;
+  RefPtr<SlicedInputStream> sis =
+    CreateNonSeekableStreams(500, 0, 500000, buf);
+
+  uint64_t length;
+  ASSERT_EQ(NS_OK, sis->Available(&length));
+  ASSERT_EQ((uint64_t)500, length);
+
+  char buf2[4096];
+  uint32_t count;
+  ASSERT_EQ(NS_OK, sis->Read(buf2, sizeof(buf2), &count));
+  ASSERT_EQ((uint64_t)500, count);
+}
+
+// What if the length is 0?
+TEST(TestSlicedInputStream, Length0) {
+  nsCString buf;
+  RefPtr<SlicedInputStream> sis =
+    CreateNonSeekableStreams(500, 0, 0, buf);
+
+  uint64_t length;
+  ASSERT_EQ(NS_OK, sis->Available(&length));
+  ASSERT_EQ((uint64_t)0, length);
+
+  char buf2[4096];
+  uint32_t count;
+  ASSERT_EQ(NS_OK, sis->Read(buf2, sizeof(buf2), &count));
+  ASSERT_EQ((uint64_t)0, count);
+}
diff --git a/xpcom/tests/gtest/TestSnappyStreams.cpp b/xpcom/tests/gtest/TestSnappyStreams.cpp
new file mode 100644
index 000000000..99f41120b
--- /dev/null
+++ b/xpcom/tests/gtest/TestSnappyStreams.cpp
@@ -0,0 +1,191 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <algorithm>
+#include "gtest/gtest.h"
+#include "Helpers.h"
+#include "mozilla/SnappyCompressOutputStream.h"
+#include "mozilla/SnappyUncompressInputStream.h"
+#include "nsIPipe.h"
+#include "nsStreamUtils.h"
+#include "nsString.h"
+#include "nsStringStream.h"
+#include "nsTArray.h"
+
+namespace {
+
+using mozilla::SnappyCompressOutputStream;
+using mozilla::SnappyUncompressInputStream;
+
+static already_AddRefed<nsIOutputStream>
+CompressPipe(nsIInputStream** aReaderOut)
+{
+  nsCOMPtr<nsIOutputStream> pipeWriter;
+
+  nsresult rv = NS_NewPipe(aReaderOut, getter_AddRefs(pipeWriter));
+  if (NS_FAILED(rv)) { return nullptr; }
+
+  nsCOMPtr<nsIOutputStream> compress =
+    new SnappyCompressOutputStream(pipeWriter);
+  return compress.forget();
+}
+
+// Verify the given number of bytes compresses to a smaller number of bytes.
+static void TestCompress(uint32_t aNumBytes)
+{
+  // Don't permit this test on small data sizes as snappy can slightly
+  // bloat very small content.
+  ASSERT_GT(aNumBytes, 1024u);
+
+  nsCOMPtr<nsIInputStream> pipeReader;
+  nsCOMPtr<nsIOutputStream> compress = CompressPipe(getter_AddRefs(pipeReader));
+  ASSERT_TRUE(compress);
+
+  nsTArray<char> inputData;
+  testing::CreateData(aNumBytes, inputData);
+
+  testing::WriteAllAndClose(compress, inputData);
+
+  nsAutoCString outputData;
+  nsresult rv = NS_ConsumeStream(pipeReader, UINT32_MAX, outputData);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  ASSERT_LT(outputData.Length(), inputData.Length());
+}
+
+// Verify that the given number of bytes can be compressed and uncompressed
+// successfully.
+static void TestCompressUncompress(uint32_t aNumBytes)
+{
+  nsCOMPtr<nsIInputStream> pipeReader;
+  nsCOMPtr<nsIOutputStream> compress = CompressPipe(getter_AddRefs(pipeReader));
+  ASSERT_TRUE(compress);
+
+  nsCOMPtr<nsIInputStream> uncompress =
+    new SnappyUncompressInputStream(pipeReader);
+
+  nsTArray<char> inputData;
+  testing::CreateData(aNumBytes, inputData);
+
+  testing::WriteAllAndClose(compress, inputData);
+
+  nsAutoCString outputData;
+  nsresult rv = NS_ConsumeStream(uncompress, UINT32_MAX, outputData);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  ASSERT_EQ(inputData.Length(), outputData.Length());
+  for (uint32_t i = 0; i < inputData.Length(); ++i) {
+    EXPECT_EQ(inputData[i], outputData.get()[i]) << "Byte " << i;
+  }
+}
+
+static void TestUncompressCorrupt(const char* aCorruptData,
+                                  uint32_t aCorruptLength)
+{
+  nsCOMPtr<nsIInputStream> source;
+  nsresult rv = NS_NewByteInputStream(getter_AddRefs(source), aCorruptData,
+                                      aCorruptLength);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsIInputStream> uncompress =
+    new SnappyUncompressInputStream(source);
+
+  nsAutoCString outputData;
+  rv = NS_ConsumeStream(uncompress, UINT32_MAX, outputData);
+  ASSERT_EQ(NS_ERROR_CORRUPTED_CONTENT, rv);
+}
+
+} // namespace
+
+TEST(SnappyStream, Compress_32k)
+{
+  TestCompress(32 * 1024);
+}
+
+TEST(SnappyStream, Compress_64k)
+{
+  TestCompress(64 * 1024);
+}
+
+TEST(SnappyStream, Compress_128k)
+{
+  TestCompress(128 * 1024);
+}
+
+TEST(SnappyStream, CompressUncompress_0)
+{
+  TestCompressUncompress(0);
+}
+
+TEST(SnappyStream, CompressUncompress_1)
+{
+  TestCompressUncompress(1);
+}
+
+TEST(SnappyStream, CompressUncompress_32)
+{
+  TestCompressUncompress(32);
+}
+
+TEST(SnappyStream, CompressUncompress_1k)
+{
+  TestCompressUncompress(1024);
+}
+
+TEST(SnappyStream, CompressUncompress_32k)
+{
+  TestCompressUncompress(32 * 1024);
+}
+
+TEST(SnappyStream, CompressUncompress_64k)
+{
+  TestCompressUncompress(64 * 1024);
+}
+
+TEST(SnappyStream, CompressUncompress_128k)
+{
+  TestCompressUncompress(128 * 1024);
+}
+
+// Test buffers that are not exactly power-of-2 in length to try to
+// exercise more edge cases.  The number 13 is arbitrary.
+
+TEST(SnappyStream, CompressUncompress_256k_less_13)
+{
+  TestCompressUncompress((256 * 1024) - 13);
+}
+
+TEST(SnappyStream, CompressUncompress_256k)
+{
+  TestCompressUncompress(256 * 1024);
+}
+
+TEST(SnappyStream, CompressUncompress_256k_plus_13)
+{
+  TestCompressUncompress((256 * 1024) + 13);
+}
+
+TEST(SnappyStream, UncompressCorruptStreamIdentifier)
+{
+  static const char data[] = "This is not a valid compressed stream";
+  TestUncompressCorrupt(data, strlen(data));
+}
+
+TEST(SnappyStream, UncompressCorruptCompressedDataLength)
+{
+  static const char data[] = "\xff\x06\x00\x00sNaPpY" // stream identifier
+                             "\x00\x99\x00\x00This is not a valid compressed stream";
+  static const uint32_t dataLength = (sizeof(data) / sizeof(const char)) - 1;
+  TestUncompressCorrupt(data, dataLength);
+}
+
+TEST(SnappyStream, UncompressCorruptCompressedDataContent)
+{
+  static const char data[] = "\xff\x06\x00\x00sNaPpY" // stream identifier
+                             "\x00\x25\x00\x00This is not a valid compressed stream";
+  static const uint32_t dataLength = (sizeof(data) / sizeof(const char)) - 1;
+  TestUncompressCorrupt(data, dataLength);
+}
diff --git a/xpcom/tests/gtest/TestStateWatching.cpp b/xpcom/tests/gtest/TestStateWatching.cpp
new file mode 100644
index 000000000..16d06a5ff
--- /dev/null
+++ b/xpcom/tests/gtest/TestStateWatching.cpp
@@ -0,0 +1,46 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "gtest/gtest.h"
+#include "mozilla/SharedThreadPool.h"
+#include "mozilla/StateWatching.h"
+#include "mozilla/TaskQueue.h"
+#include "nsISupportsImpl.h"
+#include "VideoUtils.h"
+
+namespace TestStateWatching {
+
+using namespace mozilla;
+
+struct Foo {
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(Foo)
+  void Notify() { mNotified = true; }
+  bool mNotified = false;
+private:
+  ~Foo() {}
+};
+
+TEST(WatchManager, Shutdown)
+{
+  RefPtr<TaskQueue> queue = new TaskQueue(
+    GetMediaThreadPool(MediaThreadType::PLAYBACK));
+
+  RefPtr<Foo> p = new Foo;
+  WatchManager<Foo> manager(p, queue);
+  Watchable<bool> notifier(false, "notifier");
+
+  queue->Dispatch(NS_NewRunnableFunction([&] () {
+    manager.Watch(notifier, &Foo::Notify);
+    notifier = true; // Trigger the call to Foo::Notify().
+    manager.Shutdown(); // Shutdown() should cancel the call.
+  }));
+
+  queue->BeginShutdown();
+  queue->AwaitShutdownAndIdle();
+  EXPECT_FALSE(p->mNotified);
+}
+
+} // namespace TestStateWatching
diff --git a/xpcom/tests/gtest/TestStorageStream.cpp b/xpcom/tests/gtest/TestStorageStream.cpp
new file mode 100644
index 000000000..a49d6f6bc
--- /dev/null
+++ b/xpcom/tests/gtest/TestStorageStream.cpp
@@ -0,0 +1,131 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdlib.h>
+#include "gtest/gtest.h"
+#include "Helpers.h"
+#include "nsCOMPtr.h"
+#include "nsICloneableInputStream.h"
+#include "nsIInputStream.h"
+#include "nsIOutputStream.h"
+#include "nsIStorageStream.h"
+#include "nsTArray.h"
+
+namespace {
+
+void
+WriteData(nsIOutputStream* aOut, nsTArray<char>& aData, uint32_t aNumBytes,
+          nsACString& aDataWritten)
+{
+  uint32_t n;
+  nsresult rv = aOut->Write(aData.Elements(), aNumBytes, &n);
+  EXPECT_TRUE(NS_SUCCEEDED(rv));
+  aDataWritten.Append(aData.Elements(), aNumBytes);
+}
+
+} // namespace
+
+TEST(StorageStreams, Main)
+{
+  // generate some test data we will write in 4k chunks to the stream
+  nsTArray<char> kData;
+  testing::CreateData(4096, kData);
+
+  // track how much data was written so we can compare at the end
+  nsAutoCString dataWritten;
+
+  nsresult rv;
+  nsCOMPtr<nsIStorageStream> stor;
+
+  rv = NS_NewStorageStream(kData.Length(), UINT32_MAX, getter_AddRefs(stor));
+  EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsIOutputStream> out;
+  rv = stor->GetOutputStream(0, getter_AddRefs(out));
+  EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+  WriteData(out, kData, kData.Length(), dataWritten);
+  WriteData(out, kData, kData.Length(), dataWritten);
+
+  rv = out->Close();
+  EXPECT_TRUE(NS_SUCCEEDED(rv));
+  out = nullptr;
+
+  nsCOMPtr<nsIInputStream> in;
+  rv = stor->NewInputStream(0, getter_AddRefs(in));
+  EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsICloneableInputStream> cloneable = do_QueryInterface(in);
+  ASSERT_TRUE(cloneable != nullptr);
+  ASSERT_TRUE(cloneable->GetCloneable());
+
+  nsCOMPtr<nsIInputStream> clone;
+  rv = cloneable->Clone(getter_AddRefs(clone));
+
+  testing::ConsumeAndValidateStream(in, dataWritten);
+  testing::ConsumeAndValidateStream(clone, dataWritten);
+  in = nullptr;
+  clone = nullptr;
+
+  // now, write 3 more full 4k segments + 11 bytes, starting at 8192
+  // total written equals 20491 bytes
+
+  rv = stor->GetOutputStream(dataWritten.Length(), getter_AddRefs(out));
+  EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+  WriteData(out, kData, kData.Length(), dataWritten);
+  WriteData(out, kData, kData.Length(), dataWritten);
+  WriteData(out, kData, kData.Length(), dataWritten);
+  WriteData(out, kData, 11, dataWritten);
+
+  rv = out->Close();
+  EXPECT_TRUE(NS_SUCCEEDED(rv));
+  out = nullptr;
+
+  // now, read all
+  rv = stor->NewInputStream(0, getter_AddRefs(in));
+  EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+  testing::ConsumeAndValidateStream(in, dataWritten);
+  in = nullptr;
+}
+
+TEST(StorageStreams, EarlyInputStream)
+{
+  // generate some test data we will write in 4k chunks to the stream
+  nsTArray<char> kData;
+  testing::CreateData(4096, kData);
+
+  // track how much data was written so we can compare at the end
+  nsAutoCString dataWritten;
+
+  nsresult rv;
+  nsCOMPtr<nsIStorageStream> stor;
+
+  rv = NS_NewStorageStream(kData.Length(), UINT32_MAX, getter_AddRefs(stor));
+  EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+  // Get input stream before writing data into the output stream
+  nsCOMPtr<nsIInputStream> in;
+  rv = stor->NewInputStream(0, getter_AddRefs(in));
+  EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+  // Write data to output stream
+  nsCOMPtr<nsIOutputStream> out;
+  rv = stor->GetOutputStream(0, getter_AddRefs(out));
+  EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+  WriteData(out, kData, kData.Length(), dataWritten);
+  WriteData(out, kData, kData.Length(), dataWritten);
+
+  rv = out->Close();
+  EXPECT_TRUE(NS_SUCCEEDED(rv));
+  out = nullptr;
+
+  // Should be able to consume input stream
+  testing::ConsumeAndValidateStream(in, dataWritten);
+  in = nullptr;
+}
diff --git a/xpcom/tests/gtest/TestStringStream.cpp b/xpcom/tests/gtest/TestStringStream.cpp
new file mode 100644
index 000000000..5591ed588
--- /dev/null
+++ b/xpcom/tests/gtest/TestStringStream.cpp
@@ -0,0 +1,65 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "gtest/gtest.h"
+#include "Helpers.h"
+#include "nsICloneableInputStream.h"
+#include "nsStringStream.h"
+#include "nsTArray.h"
+#include "nsIInputStream.h"
+#include "nsCOMPtr.h"
+
+namespace {
+
+static void TestStringStream(uint32_t aNumBytes)
+{
+  nsTArray<char> inputData;
+  testing::CreateData(aNumBytes, inputData);
+  nsDependentCSubstring inputString(inputData.Elements(), inputData.Length());
+
+  nsCOMPtr<nsIInputStream> stream;
+  nsresult rv = NS_NewCStringInputStream(getter_AddRefs(stream), inputString);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  testing::ConsumeAndValidateStream(stream, inputString);
+}
+
+static void TestStringStreamClone(uint32_t aNumBytes)
+{
+  nsTArray<char> inputData;
+  testing::CreateData(aNumBytes, inputData);
+  nsDependentCSubstring inputString(inputData.Elements(), inputData.Length());
+
+  nsCOMPtr<nsIInputStream> stream;
+  nsresult rv = NS_NewCStringInputStream(getter_AddRefs(stream), inputString);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsICloneableInputStream> cloneable = do_QueryInterface(stream);
+  ASSERT_TRUE(cloneable != nullptr);
+  ASSERT_TRUE(cloneable->GetCloneable());
+
+  nsCOMPtr<nsIInputStream> clone;
+  rv = cloneable->Clone(getter_AddRefs(clone));
+
+  testing::ConsumeAndValidateStream(stream, inputString);
+
+  // Release the stream to verify that the clone's string survives correctly.
+  stream = nullptr;
+
+  testing::ConsumeAndValidateStream(clone, inputString);
+}
+
+} // namespace
+
+TEST(StringStream, Simple_4k)
+{
+  TestStringStream(1024 * 4);
+}
+
+TEST(StringStream, Clone_4k)
+{
+  TestStringStreamClone(1024 * 4);
+}
diff --git a/xpcom/tests/gtest/TestStrings.cpp b/xpcom/tests/gtest/TestStrings.cpp
new file mode 100644
index 000000000..285021b8e
--- /dev/null
+++ b/xpcom/tests/gtest/TestStrings.cpp
@@ -0,0 +1,982 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "nsString.h"
+#include "nsStringBuffer.h"
+#include "nsReadableUtils.h"
+#include "nsCRTGlue.h"
+#include "mozilla/RefPtr.h"
+#include "nsTArray.h"
+#include "gtest/gtest.h"
+
+namespace TestStrings {
+
+using mozilla::fallible;
+
+void test_assign_helper(const nsACString& in, nsACString &_retval)
+{
+  _retval = in;
+}
+
+TEST(Strings, assign)
+{
+  nsCString result;
+  test_assign_helper(NS_LITERAL_CSTRING("a") + NS_LITERAL_CSTRING("b"), result);
+  EXPECT_STREQ(result.get(), "ab");
+}
+
+TEST(Strings, assign_c)
+{
+  nsCString c; c.Assign('c');
+  EXPECT_STREQ(c.get(), "c");
+}
+
+TEST(Strings, test1)
+{
+  NS_NAMED_LITERAL_STRING(empty, "");
+  const nsAString& aStr = empty;
+
+  nsAutoString buf(aStr);
+
+  int32_t n = buf.FindChar(',');
+  EXPECT_EQ(n, kNotFound);
+
+  n = buf.Length();
+
+  buf.Cut(0, n + 1);
+  n = buf.FindChar(',');
+
+  EXPECT_EQ(n, kNotFound);
+}
+
+TEST(Strings, test2)
+{
+  nsCString data("hello world");
+  const nsACString& aStr = data;
+
+  nsCString temp(aStr);
+  temp.Cut(0, 6);
+
+  EXPECT_STREQ(temp.get(), "world");
+}
+
+TEST(Strings, find)
+{
+  nsCString src("<!DOCTYPE blah blah blah>");
+
+  int32_t i = src.Find("DOCTYPE", true, 2, 1);
+  EXPECT_EQ(i, 2);
+}
+
+TEST(Strings, rfind)
+{
+  const char text[] = "<!DOCTYPE blah blah blah>";
+  const char term[] = "bLaH";
+  nsCString src(text);
+  int32_t i;
+
+  i = src.RFind(term, true, 3, -1); 
+  EXPECT_EQ(i, kNotFound);
+
+  i = src.RFind(term, true, -1, -1);
+  EXPECT_EQ(i, 20);
+
+  i = src.RFind(term, true, 13, -1);
+  EXPECT_EQ(i, 10);
+
+  i = src.RFind(term, true, 22, 3);
+  EXPECT_EQ(i, 20);
+}
+
+TEST(Strings, rfind_2)
+{
+  const char text[] = "<!DOCTYPE blah blah blah>";
+  nsCString src(text);
+  int32_t i = src.RFind("TYPE", false, 5, -1); 
+  EXPECT_EQ(i, 5);
+}
+
+TEST(Strings, rfind_3)
+{
+  const char text[] = "urn:mozilla:locale:en-US:necko";
+  nsAutoCString value(text);
+  int32_t i = value.RFind(":");
+  EXPECT_EQ(i, 24);
+}
+
+TEST(Strings, rfind_4)
+{
+  nsCString value("a.msf");
+  int32_t i = value.RFind(".msf");
+  EXPECT_EQ(i, 1);
+}
+
+TEST(Strings, findinreadable)
+{
+  const char text[] = "jar:jar:file:///c:/software/mozilla/mozilla_2006_02_21.jar!/browser/chrome/classic.jar!/";
+  nsAutoCString value(text);
+
+  nsACString::const_iterator begin, end;
+  value.BeginReading(begin);
+  value.EndReading(end);
+  nsACString::const_iterator delim_begin (begin),
+                             delim_end   (end);
+
+  // Search for last !/ at the end of the string
+  EXPECT_TRUE(FindInReadable(NS_LITERAL_CSTRING("!/"), delim_begin, delim_end));
+  char *r = ToNewCString(Substring(delim_begin, delim_end));
+  // Should match the first "!/" but not the last
+  EXPECT_NE(delim_end, end);
+  EXPECT_STREQ(r, "!/");
+  free(r);
+
+  delim_begin = begin;
+  delim_end = end;
+
+  // Search for first jar:
+  EXPECT_TRUE(FindInReadable(NS_LITERAL_CSTRING("jar:"), delim_begin, delim_end));
+
+  r = ToNewCString(Substring(delim_begin, delim_end));
+  // Should not match the first jar:, but the second one
+  EXPECT_EQ(delim_begin, begin);
+  EXPECT_STREQ(r, "jar:");
+  free(r);
+
+  // Search for jar: in a Substring
+  delim_begin = begin; delim_begin++;
+  delim_end = end;
+  EXPECT_TRUE(FindInReadable(NS_LITERAL_CSTRING("jar:"), delim_begin, delim_end));
+
+  r = ToNewCString(Substring(delim_begin, delim_end));
+  // Should not match the first jar:, but the second one
+  EXPECT_NE(delim_begin, begin);
+  EXPECT_STREQ(r, "jar:");
+  free(r);
+
+  // Should not find a match
+  EXPECT_FALSE(FindInReadable(NS_LITERAL_CSTRING("gecko"), delim_begin, delim_end));
+
+  // When no match is found, range should be empty
+  EXPECT_EQ(delim_begin, delim_end);
+
+  // Should not find a match (search not beyond Substring)
+  delim_begin = begin; for (int i=0;i<6;i++) delim_begin++;
+  delim_end = end;
+  EXPECT_FALSE(FindInReadable(NS_LITERAL_CSTRING("jar:"), delim_begin, delim_end));
+
+  // When no match is found, range should be empty
+  EXPECT_EQ(delim_begin, delim_end);
+
+  // Should not find a match (search not beyond Substring)
+  delim_begin = begin;
+  delim_end = end; for (int i=0;i<7;i++) delim_end--;
+  EXPECT_FALSE(FindInReadable(NS_LITERAL_CSTRING("classic"), delim_begin, delim_end));
+
+  // When no match is found, range should be empty
+  EXPECT_EQ(delim_begin, delim_end);
+}
+
+TEST(Strings, rfindinreadable)
+{
+  const char text[] = "jar:jar:file:///c:/software/mozilla/mozilla_2006_02_21.jar!/browser/chrome/classic.jar!/";
+  nsAutoCString value(text);
+
+  nsACString::const_iterator begin, end;
+  value.BeginReading(begin);
+  value.EndReading(end);
+  nsACString::const_iterator delim_begin (begin),
+                             delim_end   (end);
+
+  // Search for last !/ at the end of the string
+  EXPECT_TRUE(RFindInReadable(NS_LITERAL_CSTRING("!/"), delim_begin, delim_end));
+  char *r = ToNewCString(Substring(delim_begin, delim_end));
+  // Should match the last "!/"
+  EXPECT_EQ(delim_end, end);
+  EXPECT_STREQ(r, "!/");
+  free(r);
+
+  delim_begin = begin;
+  delim_end = end;
+
+  // Search for last jar: but not the first one...
+  EXPECT_TRUE(RFindInReadable(NS_LITERAL_CSTRING("jar:"), delim_begin, delim_end));
+
+  r = ToNewCString(Substring(delim_begin, delim_end));
+  // Should not match the first jar:, but the second one
+  EXPECT_NE(delim_begin, begin);
+  EXPECT_STREQ(r, "jar:");
+  free(r);
+
+  // Search for jar: in a Substring
+  delim_begin = begin;
+  delim_end = begin; for (int i=0;i<6;i++) delim_end++;
+  EXPECT_TRUE(RFindInReadable(NS_LITERAL_CSTRING("jar:"), delim_begin, delim_end));
+
+  r = ToNewCString(Substring(delim_begin, delim_end));
+  // Should not match the first jar:, but the second one
+  EXPECT_EQ(delim_begin, begin);
+  EXPECT_STREQ(r, "jar:");
+  free(r);
+
+  // Should not find a match
+  delim_begin = begin;
+  delim_end = end;
+  EXPECT_FALSE(RFindInReadable(NS_LITERAL_CSTRING("gecko"), delim_begin, delim_end));
+
+  // When no match is found, range should be empty
+  EXPECT_EQ(delim_begin, delim_end);
+
+  // Should not find a match (search not before Substring)
+  delim_begin = begin; for (int i=0;i<6;i++) delim_begin++;
+  delim_end = end;
+  EXPECT_FALSE(RFindInReadable(NS_LITERAL_CSTRING("jar:"), delim_begin, delim_end));
+
+  // When no match is found, range should be empty
+  EXPECT_EQ(delim_begin, delim_end);
+
+  // Should not find a match (search not beyond Substring)
+  delim_begin = begin;
+  delim_end = end; for (int i=0;i<7;i++) delim_end--;
+  EXPECT_FALSE(RFindInReadable(NS_LITERAL_CSTRING("classic"), delim_begin, delim_end));
+
+  // When no match is found, range should be empty
+  EXPECT_EQ(delim_begin, delim_end);
+}
+
+TEST(Strings, distance)
+{
+  const char text[] = "abc-xyz";
+  nsCString s(text);
+  nsCString::const_iterator begin, end;
+  s.BeginReading(begin);
+  s.EndReading(end);
+  size_t d = Distance(begin, end);
+  EXPECT_EQ(d, sizeof(text) - 1);
+}
+
+TEST(Strings, length)
+{
+  const char text[] = "abc-xyz";
+  nsCString s(text);
+  size_t d = s.Length();
+  EXPECT_EQ(d, sizeof(text) - 1);
+}
+
+TEST(Strings, trim)
+{
+  const char text[] = " a\t    $   ";
+  const char set[] = " \t$";
+
+  nsCString s(text);
+  s.Trim(set);
+  EXPECT_STREQ(s.get(), "a");
+}
+
+TEST(Strings, replace_substr)
+{
+  const char text[] = "abc-ppp-qqq-ppp-xyz";
+  nsCString s(text);
+  s.ReplaceSubstring("ppp", "www");
+  EXPECT_STREQ(s.get(), "abc-www-qqq-www-xyz");
+
+  s.Assign("foobar");
+  s.ReplaceSubstring("foo", "bar");
+  s.ReplaceSubstring("bar", "");
+  EXPECT_STREQ(s.get(), "");
+
+  s.Assign("foofoofoo");
+  s.ReplaceSubstring("foo", "foo");
+  EXPECT_STREQ(s.get(), "foofoofoo");
+
+  s.Assign("foofoofoo");
+  s.ReplaceSubstring("of", "fo");
+  EXPECT_STREQ(s.get(), "fofoofooo");
+}
+
+TEST(Strings, replace_substr_2)
+{
+  const char *oldName = nullptr;
+  const char *newName = "user";
+  nsString acctName; acctName.AssignLiteral("forums.foo.com");
+  nsAutoString newAcctName, oldVal, newVal;
+  oldVal.AssignWithConversion(oldName);
+  newVal.AssignWithConversion(newName);
+  newAcctName.Assign(acctName);
+
+  // here, oldVal is empty.  we are testing that this function
+  // does not hang.  see bug 235355.
+  newAcctName.ReplaceSubstring(oldVal, newVal);
+
+  // we expect that newAcctName will be unchanged.
+  EXPECT_TRUE(newAcctName.Equals(acctName));
+}
+
+TEST(Strings, replace_substr_3)
+{
+  nsCString s;
+  s.Assign("abcabcabc");
+  s.ReplaceSubstring("ca", "X");
+  EXPECT_STREQ(s.get(), "abXbXbc");
+
+  s.Assign("abcabcabc");
+  s.ReplaceSubstring("ca", "XYZ");
+  EXPECT_STREQ(s.get(), "abXYZbXYZbc");
+
+  s.Assign("abcabcabc");
+  s.ReplaceSubstring("ca", "XY");
+  EXPECT_STREQ(s.get(), "abXYbXYbc");
+
+  s.Assign("abcabcabc");
+  s.ReplaceSubstring("ca", "XYZ!");
+  EXPECT_STREQ(s.get(), "abXYZ!bXYZ!bc");
+
+  s.Assign("abcdabcdabcd");
+  s.ReplaceSubstring("bcd", "X");
+  EXPECT_STREQ(s.get(), "aXaXaX");
+
+  s.Assign("abcdabcdabcd");
+  s.ReplaceSubstring("bcd", "XYZ!");
+  EXPECT_STREQ(s.get(), "aXYZ!aXYZ!aXYZ!");
+
+  s.Assign("abcdabcdabcd");
+  s.ReplaceSubstring("bcd", "XY");
+  EXPECT_STREQ(s.get(), "aXYaXYaXY");
+
+  s.Assign("abcdabcdabcd");
+  s.ReplaceSubstring("bcd", "XYZABC");
+  EXPECT_STREQ(s.get(), "aXYZABCaXYZABCaXYZABC");
+
+  s.Assign("abcdabcdabcd");
+  s.ReplaceSubstring("bcd", "XYZ");
+  EXPECT_STREQ(s.get(), "aXYZaXYZaXYZ");
+
+  s.Assign("abcdabcdabcd");
+  s.ReplaceSubstring("bcd", "XYZ!");
+  EXPECT_STREQ(s.get(), "aXYZ!aXYZ!aXYZ!");
+
+  s.Assign("abcdabcdabcd");
+  s.ReplaceSubstring("ab", "X");
+  EXPECT_STREQ(s.get(), "XcdXcdXcd");
+
+  s.Assign("abcdabcdabcd");
+  s.ReplaceSubstring("ab", "XYZABC");
+  EXPECT_STREQ(s.get(), "XYZABCcdXYZABCcdXYZABCcd");
+
+  s.Assign("abcdabcdabcd");
+  s.ReplaceSubstring("ab", "XY");
+  EXPECT_STREQ(s.get(), "XYcdXYcdXYcd");
+
+  s.Assign("abcdabcdabcd");
+  s.ReplaceSubstring("ab", "XYZ!");
+  EXPECT_STREQ(s.get(), "XYZ!cdXYZ!cdXYZ!cd");
+
+  s.Assign("abcdabcdabcd");
+  s.ReplaceSubstring("notfound", "X");
+  EXPECT_STREQ(s.get(), "abcdabcdabcd");
+
+  s.Assign("abcdabcdabcd");
+  s.ReplaceSubstring("notfound", "longlongstring");
+  EXPECT_STREQ(s.get(), "abcdabcdabcd");
+}
+
+TEST(Strings, strip_ws)
+{
+  const char text[] = " a    $   ";
+  nsCString s(text);
+  s.StripWhitespace();
+  EXPECT_STREQ(s.get(), "a$");
+}
+
+TEST(Strings, equals_ic)
+{
+  nsCString s;
+  EXPECT_FALSE(s.LowerCaseEqualsLiteral("view-source"));
+}
+
+TEST(Strings, fixed_string)
+{
+  char buf[256] = "hello world";
+
+  nsFixedCString s(buf, sizeof(buf));
+
+  EXPECT_EQ(s.Length(), strlen(buf));
+
+  EXPECT_STREQ(s.get(), buf);
+
+  s.Assign("foopy doopy doo");
+  EXPECT_EQ(s.get(), buf);
+}
+
+TEST(Strings, concat)
+{
+  nsCString bar("bar");
+  const nsACString& barRef = bar;
+
+  const nsPromiseFlatCString& result =
+      PromiseFlatCString(NS_LITERAL_CSTRING("foo") +
+                         NS_LITERAL_CSTRING(",") +
+                         barRef);
+  EXPECT_STREQ(result.get(), "foo,bar");
+}
+
+TEST(Strings, concat_2)
+{
+  nsCString fieldTextStr("xyz");
+  nsCString text("text");
+  const nsACString& aText = text;
+
+  nsAutoCString result( fieldTextStr + aText );
+
+  EXPECT_STREQ(result.get(), "xyztext");
+}
+
+TEST(Strings, concat_3)
+{
+  nsCString result;
+  nsCString ab("ab"), c("c");
+
+  result = ab + result + c;
+  EXPECT_STREQ(result.get(), "abc");
+}
+
+TEST(Strings, xpidl_string)
+{
+  nsXPIDLCString a, b;
+  a = b;
+  EXPECT_TRUE(a == b);
+
+  a.Adopt(0);
+  EXPECT_TRUE(a == b);
+
+  a.Append("foopy");
+  a.Assign(b);
+  EXPECT_TRUE(a == b);
+
+  a.Insert("", 0);
+  a.Assign(b);
+  EXPECT_TRUE(a == b);
+
+  const char text[] = "hello world";
+  *getter_Copies(a) = NS_strdup(text);
+  EXPECT_STREQ(a, text);
+
+  b = a;
+  EXPECT_STREQ(a, b);
+
+  a.Adopt(0);
+  nsACString::const_iterator begin, end;
+  a.BeginReading(begin);
+  a.EndReading(end);
+  char *r = ToNewCString(Substring(begin, end));
+  EXPECT_STREQ(r, "");
+  free(r);
+
+  a.Adopt(0);
+  EXPECT_TRUE(a.IsVoid());
+
+  int32_t index = a.FindCharInSet("xyz");
+  EXPECT_EQ(index, kNotFound);
+}
+
+TEST(Strings, empty_assign)
+{
+  nsCString a;
+  a.AssignLiteral("");
+
+  a.AppendLiteral("");
+
+  nsCString b;
+  b.SetCapacity(0);
+}
+
+TEST(Strings, set_length)
+{
+  const char kText[] = "Default Plugin";
+  nsCString buf;
+  buf.SetCapacity(sizeof(kText)-1);
+  buf.Assign(kText);
+  buf.SetLength(sizeof(kText)-1);
+  EXPECT_STREQ(buf.get(), kText);
+}
+
+TEST(Strings, substring)
+{
+  nsCString super("hello world"), sub("hello");
+
+  // this tests that |super| starts with |sub|,
+  
+  EXPECT_TRUE(sub.Equals(StringHead(super, sub.Length())));
+
+  // and verifies that |sub| does not start with |super|.
+
+  EXPECT_FALSE(super.Equals(StringHead(sub, super.Length())));
+}
+
+#define test_append_expect(str, int, suffix, expect) \
+  str.Truncate(); \
+  str.AppendInt(suffix = int); \
+  EXPECT_TRUE(str.EqualsLiteral(expect));
+
+#define test_appends_expect(int, suffix, expect) \
+  test_append_expect(str, int, suffix, expect) \
+  test_append_expect(cstr, int, suffix, expect)
+
+#define test_appendbase(str, prefix, int, suffix, base) \
+  str.Truncate(); \
+  str.AppendInt(suffix = prefix ## int ## suffix, base); \
+  EXPECT_TRUE(str.EqualsLiteral(#int));
+
+#define test_appendbases(prefix, int, suffix, base) \
+  test_appendbase(str, prefix, int, suffix, base) \
+  test_appendbase(cstr, prefix, int, suffix, base)
+
+TEST(Strings, appendint)
+{
+  nsString str;
+  nsCString cstr;
+  int32_t L;
+  uint32_t UL;
+  int64_t LL;
+  uint64_t ULL;
+  test_appends_expect(INT32_MAX, L, "2147483647")
+  test_appends_expect(INT32_MIN, L, "-2147483648")
+  test_appends_expect(UINT32_MAX, UL, "4294967295")
+  test_appends_expect(INT64_MAX, LL, "9223372036854775807")
+  test_appends_expect(INT64_MIN, LL, "-9223372036854775808")
+  test_appends_expect(UINT64_MAX, ULL, "18446744073709551615")
+  test_appendbases(0, 17777777777, L, 8)
+  test_appendbases(0, 20000000000, L, 8)
+  test_appendbases(0, 37777777777, UL, 8)
+  test_appendbases(0, 777777777777777777777, LL, 8)
+  test_appendbases(0, 1000000000000000000000, LL, 8)
+  test_appendbases(0, 1777777777777777777777, ULL, 8)
+  test_appendbases(0x, 7fffffff, L, 16)
+  test_appendbases(0x, 80000000, L, 16)
+  test_appendbases(0x, ffffffff, UL, 16)
+  test_appendbases(0x, 7fffffffffffffff, LL, 16)
+  test_appendbases(0x, 8000000000000000, LL, 16)
+  test_appendbases(0x, ffffffffffffffff, ULL, 16)
+}
+
+TEST(Strings, appendint64)
+{
+  nsCString str;
+
+  int64_t max = INT64_MAX;
+  static const char max_expected[] = "9223372036854775807";
+  int64_t min = INT64_MIN;
+  static const char min_expected[] = "-9223372036854775808";
+  static const char min_expected_oct[] = "1000000000000000000000";
+  int64_t maxint_plus1 = 1LL << 32;
+  static const char maxint_plus1_expected[] = "4294967296";
+  static const char maxint_plus1_expected_x[] = "100000000";
+
+  str.AppendInt(max);
+
+  EXPECT_TRUE(str.Equals(max_expected));
+
+  str.Truncate();
+  str.AppendInt(min);
+  EXPECT_TRUE(str.Equals(min_expected));
+  str.Truncate();
+  str.AppendInt(min, 8);
+  EXPECT_TRUE(str.Equals(min_expected_oct));
+
+
+  str.Truncate();
+  str.AppendInt(maxint_plus1);
+  EXPECT_TRUE(str.Equals(maxint_plus1_expected));
+  str.Truncate();
+  str.AppendInt(maxint_plus1, 16);
+  EXPECT_TRUE(str.Equals(maxint_plus1_expected_x));
+}
+
+TEST(Strings, appendfloat)
+{
+  nsCString str;
+  double bigdouble = 11223344556.66;
+  static const char double_expected[] = "11223344556.66";
+  static const char float_expected[] = "0.01";
+
+  // AppendFloat is used to append doubles, therefore the precision must be
+  // large enough (see bug 327719)
+  str.AppendFloat( bigdouble );
+  EXPECT_TRUE(str.Equals(double_expected));
+
+  str.Truncate();
+  // AppendFloat is used to append floats (bug 327719 #27)
+  str.AppendFloat( 0.1f * 0.1f );
+  EXPECT_TRUE(str.Equals(float_expected));
+}
+
+TEST(Strings, findcharinset)
+{
+  nsCString buf("hello, how are you?");
+
+  int32_t index = buf.FindCharInSet(",?", 5);
+  EXPECT_EQ(index, 5);
+
+  index = buf.FindCharInSet("helo", 0);
+  EXPECT_EQ(index, 0);
+
+  index = buf.FindCharInSet("z?", 6);
+  EXPECT_EQ(index, (int32_t) buf.Length() - 1);
+}
+
+TEST(Strings, rfindcharinset)
+{
+  nsCString buf("hello, how are you?");
+
+  int32_t index = buf.RFindCharInSet(",?", 5);
+  EXPECT_EQ(index, 5);
+
+  index = buf.RFindCharInSet("helo", 0);
+  EXPECT_EQ(index, 0);
+
+  index = buf.RFindCharInSet("z?", 6);
+  EXPECT_EQ(index, kNotFound);
+
+  index = buf.RFindCharInSet("l", 5);
+  EXPECT_EQ(index, 3);
+
+  buf.Assign("abcdefghijkabc");
+
+  index = buf.RFindCharInSet("ab");
+  EXPECT_EQ(index, 12);
+
+  index = buf.RFindCharInSet("ab", 11);
+  EXPECT_EQ(index, 11);
+
+  index = buf.RFindCharInSet("ab", 10);
+  EXPECT_EQ(index, 1);
+
+  index = buf.RFindCharInSet("ab", 0);
+  EXPECT_EQ(index, 0);
+
+  index = buf.RFindCharInSet("cd", 1);
+  EXPECT_EQ(index, kNotFound);
+
+  index = buf.RFindCharInSet("h");
+  EXPECT_EQ(index, 7);
+}
+
+TEST(Strings, stringbuffer)
+{
+  const char kData[] = "hello world";
+
+  RefPtr<nsStringBuffer> buf;
+
+  buf = nsStringBuffer::Alloc(sizeof(kData));
+  EXPECT_TRUE(!!buf);
+
+  buf = nsStringBuffer::Alloc(sizeof(kData));
+  EXPECT_TRUE(!!buf);
+  char *data = (char *) buf->Data();
+  memcpy(data, kData, sizeof(kData));
+
+  nsCString str;
+  buf->ToString(sizeof(kData)-1, str);
+
+  nsStringBuffer *buf2;
+  buf2 = nsStringBuffer::FromString(str);
+
+  EXPECT_EQ(buf, buf2);
+}
+
+TEST(Strings, voided)
+{
+  const char kData[] = "hello world";
+
+  nsXPIDLCString str;
+  EXPECT_FALSE(str);
+  EXPECT_TRUE(str.IsVoid());
+  EXPECT_TRUE(str.IsEmpty());
+
+  str.Assign(kData);
+  EXPECT_STREQ(str, kData);
+
+  str.SetIsVoid(true);
+  EXPECT_FALSE(str);
+  EXPECT_TRUE(str.IsVoid());
+  EXPECT_TRUE(str.IsEmpty());
+
+  str.SetIsVoid(false);
+  EXPECT_STREQ(str, "");
+}
+
+TEST(Strings, voided_autostr)
+{
+  const char kData[] = "hello world";
+
+  nsAutoCString str;
+  EXPECT_FALSE(str.IsVoid());
+  EXPECT_TRUE(str.IsEmpty());
+
+  str.Assign(kData);
+  EXPECT_STREQ(str.get(), kData);
+
+  str.SetIsVoid(true);
+  EXPECT_TRUE(str.IsVoid());
+  EXPECT_TRUE(str.IsEmpty());
+
+  str.Assign(kData);
+  EXPECT_FALSE(str.IsVoid());
+  EXPECT_FALSE(str.IsEmpty());
+  EXPECT_STREQ(str.get(), kData);
+}
+
+TEST(Strings, voided_assignment)
+{
+  nsCString a, b;
+  b.SetIsVoid(true);
+  a = b;
+  EXPECT_TRUE(a.IsVoid());
+  EXPECT_EQ(a.get(), b.get());
+}
+
+TEST(Strings, empty_assignment)
+{
+  nsCString a, b;
+  a = b;
+  EXPECT_EQ(a.get(), b.get());
+}
+
+struct ToIntegerTest
+{
+  const char *str;
+  uint32_t radix;
+  int32_t result;
+  nsresult rv;
+};
+
+static const ToIntegerTest kToIntegerTests[] = {
+  { "123", 10, 123, NS_OK },
+  { "7b", 16, 123, NS_OK },
+  { "90194313659", 10, 0, NS_ERROR_ILLEGAL_VALUE },
+  { nullptr, 0, 0, NS_OK }
+};
+
+TEST(Strings, string_tointeger)
+{
+  nsresult rv;
+  for (const ToIntegerTest* t = kToIntegerTests; t->str; ++t) {
+    int32_t result = nsAutoCString(t->str).ToInteger(&rv, t->radix);
+    EXPECT_EQ(rv, t->rv);
+    EXPECT_EQ(result, t->result);
+    result = nsAutoCString(t->str).ToInteger(&rv, t->radix);
+    EXPECT_EQ(rv, t->rv);
+    EXPECT_EQ(result, t->result);
+  }
+}
+
+static void test_parse_string_helper(const char* str, char separator, int len,
+                                       const char* s1, const char* s2)
+{
+  nsCString data(str);
+  nsTArray<nsCString> results;
+  EXPECT_TRUE(ParseString(data, separator, results));
+  EXPECT_EQ(int(results.Length()), len);
+  const char* strings[] = { s1, s2 };
+  for (int i = 0; i < len; ++i) {
+    EXPECT_TRUE(results[i].Equals(strings[i]));
+  }
+}
+
+static void test_parse_string_helper0(const char* str, char separator)
+{
+  test_parse_string_helper(str, separator, 0, nullptr, nullptr);
+}
+
+static void test_parse_string_helper1(const char* str, char separator, const char* s1)
+{
+  test_parse_string_helper(str, separator, 1, s1, nullptr);
+}
+
+static void test_parse_string_helper2(const char* str, char separator, const char* s1, const char* s2)
+{
+  test_parse_string_helper(str, separator, 2, s1, s2);
+}
+
+TEST(String, parse_string)
+{
+  test_parse_string_helper1("foo, bar", '_', "foo, bar");
+  test_parse_string_helper2("foo, bar", ',', "foo", " bar");
+  test_parse_string_helper2("foo, bar ", ' ', "foo,", "bar");
+  test_parse_string_helper2("foo,bar", 'o', "f", ",bar");
+  test_parse_string_helper0("", '_');
+  test_parse_string_helper0("  ", ' ');
+  test_parse_string_helper1(" foo", ' ', "foo");
+  test_parse_string_helper1("  foo", ' ', "foo");
+}
+
+static void test_strip_chars_helper(const char16_t* str, const char16_t* strip, const nsAString& result, uint32_t offset=0)
+{
+  nsAutoString tmp(str);
+  nsAString& data = tmp;
+  data.StripChars(strip, offset);
+  EXPECT_TRUE(data.Equals(result));
+}
+
+TEST(String, strip_chars)
+{
+  test_strip_chars_helper(u"foo \r \nbar",
+                          u" \n\r",
+                          NS_LITERAL_STRING("foobar"));
+  test_strip_chars_helper(u"\r\nfoo\r\n",
+                          u" \n\r",
+                          NS_LITERAL_STRING("foo"));
+  test_strip_chars_helper(u"foo",
+                          u" \n\r",
+                          NS_LITERAL_STRING("foo"));
+  test_strip_chars_helper(u"foo",
+                          u"fo",
+                          NS_LITERAL_STRING(""));
+  test_strip_chars_helper(u"foo",
+                          u"foo",
+                          NS_LITERAL_STRING(""));
+  test_strip_chars_helper(u" foo",
+                          u" ",
+                          NS_LITERAL_STRING(" foo"), 1);
+}
+
+TEST(Strings, huge_capacity)
+{
+  nsString a, b, c, d, e, f, g, h, i, j, k, l, m, n;
+  nsCString n1;
+
+  // Ignore the result if the address space is less than 64-bit because
+  // some of the allocations above will exhaust the address space.
+  if (sizeof(void*) >= 8) {
+    EXPECT_TRUE(a.SetCapacity(1, fallible));
+    EXPECT_FALSE(a.SetCapacity(nsString::size_type(-1)/2, fallible));
+    EXPECT_TRUE(a.SetCapacity(0, fallible));  // free the allocated memory
+
+    EXPECT_TRUE(b.SetCapacity(1, fallible));
+    EXPECT_FALSE(b.SetCapacity(nsString::size_type(-1)/2 - 1, fallible));
+    EXPECT_TRUE(b.SetCapacity(0, fallible));
+
+    EXPECT_TRUE(c.SetCapacity(1, fallible));
+    EXPECT_FALSE(c.SetCapacity(nsString::size_type(-1)/2, fallible));
+    EXPECT_TRUE(c.SetCapacity(0, fallible));
+
+    EXPECT_FALSE(d.SetCapacity(nsString::size_type(-1)/2 - 1, fallible));
+    EXPECT_FALSE(d.SetCapacity(nsString::size_type(-1)/2, fallible));
+    EXPECT_TRUE(d.SetCapacity(0, fallible));
+
+    EXPECT_FALSE(e.SetCapacity(nsString::size_type(-1)/4, fallible));
+    EXPECT_FALSE(e.SetCapacity(nsString::size_type(-1)/4 + 1, fallible));
+    EXPECT_TRUE(e.SetCapacity(0, fallible));
+
+    EXPECT_FALSE(f.SetCapacity(nsString::size_type(-1)/2, fallible));
+    EXPECT_TRUE(f.SetCapacity(0, fallible));
+
+    EXPECT_FALSE(g.SetCapacity(nsString::size_type(-1)/4 + 1000, fallible));
+    EXPECT_FALSE(g.SetCapacity(nsString::size_type(-1)/4 + 1001, fallible));
+    EXPECT_TRUE(g.SetCapacity(0, fallible));
+
+    EXPECT_FALSE(h.SetCapacity(nsString::size_type(-1)/4+1, fallible));
+    EXPECT_FALSE(h.SetCapacity(nsString::size_type(-1)/2, fallible));
+    EXPECT_TRUE(h.SetCapacity(0, fallible));
+
+    EXPECT_TRUE(i.SetCapacity(1, fallible));
+    EXPECT_TRUE(i.SetCapacity(nsString::size_type(-1)/4 - 1000, fallible));
+    EXPECT_FALSE(i.SetCapacity(nsString::size_type(-1)/4 + 1, fallible));
+    EXPECT_TRUE(i.SetCapacity(0, fallible));
+
+    EXPECT_TRUE(j.SetCapacity(nsString::size_type(-1)/4 - 1000, fallible));
+    EXPECT_FALSE(j.SetCapacity(nsString::size_type(-1)/4 + 1, fallible));
+    EXPECT_TRUE(j.SetCapacity(0, fallible));
+
+    EXPECT_TRUE(k.SetCapacity(nsString::size_type(-1)/8 - 1000, fallible));
+    EXPECT_TRUE(k.SetCapacity(nsString::size_type(-1)/4 - 1001, fallible));
+    EXPECT_TRUE(k.SetCapacity(nsString::size_type(-1)/4 - 998, fallible));
+    EXPECT_FALSE(k.SetCapacity(nsString::size_type(-1)/4 + 1, fallible));
+    EXPECT_TRUE(k.SetCapacity(0, fallible));
+
+    EXPECT_TRUE(l.SetCapacity(nsString::size_type(-1)/8, fallible));
+    EXPECT_TRUE(l.SetCapacity(nsString::size_type(-1)/8 + 1, fallible));
+    EXPECT_TRUE(l.SetCapacity(nsString::size_type(-1)/8 + 2, fallible));
+    EXPECT_TRUE(l.SetCapacity(0, fallible));
+
+    EXPECT_TRUE(m.SetCapacity(nsString::size_type(-1)/8 + 1000, fallible));
+    EXPECT_TRUE(m.SetCapacity(nsString::size_type(-1)/8 + 1001, fallible));
+    EXPECT_TRUE(m.SetCapacity(0, fallible));
+
+    EXPECT_TRUE(n.SetCapacity(nsString::size_type(-1)/8+1, fallible));
+    EXPECT_FALSE(n.SetCapacity(nsString::size_type(-1)/4, fallible));
+    EXPECT_TRUE(n.SetCapacity(0, fallible));
+
+    EXPECT_TRUE(n.SetCapacity(0, fallible));
+    EXPECT_TRUE(n.SetCapacity((nsString::size_type(-1)/2 - sizeof(nsStringBuffer)) / 2 - 2, fallible));
+    EXPECT_TRUE(n.SetCapacity(0, fallible));
+    EXPECT_FALSE(n.SetCapacity((nsString::size_type(-1)/2 - sizeof(nsStringBuffer)) / 2 - 1, fallible));
+    EXPECT_TRUE(n.SetCapacity(0, fallible));
+    EXPECT_TRUE(n1.SetCapacity(0, fallible));
+    EXPECT_TRUE(n1.SetCapacity((nsCString::size_type(-1)/2 - sizeof(nsStringBuffer)) / 1 - 2, fallible));
+    EXPECT_TRUE(n1.SetCapacity(0, fallible));
+    EXPECT_FALSE(n1.SetCapacity((nsCString::size_type(-1)/2 - sizeof(nsStringBuffer)) / 1 - 1, fallible));
+    EXPECT_TRUE(n1.SetCapacity(0, fallible));
+  }
+}
+
+static void test_tofloat_helper(const nsString& aStr, float aExpected, bool aSuccess)
+{
+  nsresult result;
+  EXPECT_EQ(aStr.ToFloat(&result), aExpected);
+  if (aSuccess) {
+    EXPECT_EQ(result, NS_OK);
+  } else {
+    EXPECT_NE(result, NS_OK);
+  }
+}
+
+TEST(Strings, tofloat)
+{
+  test_tofloat_helper(NS_LITERAL_STRING("42"), 42.f, true);
+  test_tofloat_helper(NS_LITERAL_STRING("42.0"), 42.f, true);
+  test_tofloat_helper(NS_LITERAL_STRING("-42"), -42.f, true);
+  test_tofloat_helper(NS_LITERAL_STRING("+42"), 42, true);
+  test_tofloat_helper(NS_LITERAL_STRING("13.37"), 13.37f, true);
+  test_tofloat_helper(NS_LITERAL_STRING("1.23456789"), 1.23456789f, true);
+  test_tofloat_helper(NS_LITERAL_STRING("1.98765432123456"), 1.98765432123456f, true);
+  test_tofloat_helper(NS_LITERAL_STRING("0"), 0.f, true);
+  test_tofloat_helper(NS_LITERAL_STRING("1.e5"), 100000, true);
+  test_tofloat_helper(NS_LITERAL_STRING(""), 0.f, false);
+  test_tofloat_helper(NS_LITERAL_STRING("42foo"), 42.f, false);
+  test_tofloat_helper(NS_LITERAL_STRING("foo"), 0.f, false);
+}
+
+static void test_todouble_helper(const nsString& aStr, double aExpected, bool aSuccess)
+{
+  nsresult result;
+  EXPECT_EQ(aStr.ToDouble(&result), aExpected);
+  if (aSuccess) {
+    EXPECT_EQ(result, NS_OK);
+  } else {
+    EXPECT_NE(result, NS_OK);
+  }
+}
+
+TEST(Strings, todouble)
+{
+  test_todouble_helper(NS_LITERAL_STRING("42"), 42, true);
+  test_todouble_helper(NS_LITERAL_STRING("42.0"), 42, true);
+  test_todouble_helper(NS_LITERAL_STRING("-42"), -42, true);
+  test_todouble_helper(NS_LITERAL_STRING("+42"), 42, true);
+  test_todouble_helper(NS_LITERAL_STRING("13.37"), 13.37, true);
+  test_todouble_helper(NS_LITERAL_STRING("1.23456789"), 1.23456789, true);
+  test_todouble_helper(NS_LITERAL_STRING("1.98765432123456"), 1.98765432123456, true);
+  test_todouble_helper(NS_LITERAL_STRING("123456789.98765432123456"), 123456789.98765432123456, true);
+  test_todouble_helper(NS_LITERAL_STRING("0"), 0, true);
+  test_todouble_helper(NS_LITERAL_STRING("1.e5"), 100000, true);
+  test_todouble_helper(NS_LITERAL_STRING(""), 0, false);
+  test_todouble_helper(NS_LITERAL_STRING("42foo"), 42, false);
+  test_todouble_helper(NS_LITERAL_STRING("foo"), 0, false);
+}
+
+} // namespace TestStrings
diff --git a/xpcom/tests/gtest/TestSynchronization.cpp b/xpcom/tests/gtest/TestSynchronization.cpp
new file mode 100644
index 000000000..7ec55545a
--- /dev/null
+++ b/xpcom/tests/gtest/TestSynchronization.cpp
@@ -0,0 +1,313 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/CondVar.h"
+#include "mozilla/Monitor.h"
+#include "mozilla/ReentrantMonitor.h"
+#include "mozilla/Mutex.h"
+#include "gtest/gtest.h"
+
+using namespace mozilla;
+
+static PRThread*
+spawn(void (*run)(void*), void* arg)
+{
+  return PR_CreateThread(PR_SYSTEM_THREAD,
+                         run,
+                         arg,
+                         PR_PRIORITY_NORMAL,
+                         PR_GLOBAL_THREAD,
+                         PR_JOINABLE_THREAD,
+                         0);
+}
+
+//-----------------------------------------------------------------------------
+// Sanity check: tests that can be done on a single thread
+//
+TEST(Synchronization, Sanity)
+{
+  Mutex lock("sanity::lock");
+  lock.Lock();
+  lock.AssertCurrentThreadOwns();
+  lock.Unlock();
+
+  {
+    MutexAutoLock autolock(lock);
+    lock.AssertCurrentThreadOwns();
+  }
+
+  lock.Lock();
+  lock.AssertCurrentThreadOwns();
+  {
+    MutexAutoUnlock autounlock(lock);
+  }
+  lock.AssertCurrentThreadOwns();
+  lock.Unlock();
+
+  ReentrantMonitor mon("sanity::monitor");
+  mon.Enter();
+  mon.AssertCurrentThreadIn();
+  mon.Enter();
+  mon.AssertCurrentThreadIn();
+  mon.Exit();
+  mon.AssertCurrentThreadIn();
+  mon.Exit();
+
+  {
+    ReentrantMonitorAutoEnter automon(mon);
+    mon.AssertCurrentThreadIn();
+  }
+}
+
+//-----------------------------------------------------------------------------
+// Mutex contention tests
+//
+static Mutex* gLock1;
+
+static void
+MutexContention_thread(void* /*arg*/)
+{
+  for (int i = 0; i < 100000; ++i) {
+    gLock1->Lock();
+    gLock1->AssertCurrentThreadOwns();
+    gLock1->Unlock();
+  }
+}
+
+TEST(Synchronization, MutexContention)
+{
+  gLock1 = new Mutex("lock1");
+  // PURPOSELY not checking for OOM.  YAY!
+
+  PRThread* t1 = spawn(MutexContention_thread, nullptr);
+  PRThread* t2 = spawn(MutexContention_thread, nullptr);
+  PRThread* t3 = spawn(MutexContention_thread, nullptr);
+
+  PR_JoinThread(t1);
+  PR_JoinThread(t2);
+  PR_JoinThread(t3);
+
+  delete gLock1;
+}
+
+//-----------------------------------------------------------------------------
+// Monitor tests
+//
+static Monitor* gMon1;
+
+static void
+MonitorContention_thread(void* /*arg*/)
+{
+  for (int i = 0; i < 100000; ++i) {
+    gMon1->Lock();
+    gMon1->AssertCurrentThreadOwns();
+    gMon1->Unlock();
+  }
+}
+
+TEST(Synchronization, MonitorContention)
+{
+  gMon1 = new Monitor("mon1");
+
+  PRThread* t1 = spawn(MonitorContention_thread, nullptr);
+  PRThread* t2 = spawn(MonitorContention_thread, nullptr);
+  PRThread* t3 = spawn(MonitorContention_thread, nullptr);
+
+  PR_JoinThread(t1);
+  PR_JoinThread(t2);
+  PR_JoinThread(t3);
+
+  delete gMon1;
+}
+
+
+static ReentrantMonitor* gMon2;
+
+static void
+MonitorContention2_thread(void* /*arg*/)
+{
+  for (int i = 0; i < 100000; ++i) {
+    gMon2->Enter();
+    gMon2->AssertCurrentThreadIn();
+    {
+      gMon2->Enter();
+      gMon2->AssertCurrentThreadIn();
+      gMon2->Exit();
+    }
+    gMon2->AssertCurrentThreadIn();
+    gMon2->Exit();
+  }
+}
+
+TEST(Synchronization, MonitorContention2)
+{
+  gMon2 = new ReentrantMonitor("mon1");
+
+  PRThread* t1 = spawn(MonitorContention2_thread, nullptr);
+  PRThread* t2 = spawn(MonitorContention2_thread, nullptr);
+  PRThread* t3 = spawn(MonitorContention2_thread, nullptr);
+
+  PR_JoinThread(t1);
+  PR_JoinThread(t2);
+  PR_JoinThread(t3);
+
+  delete gMon2;
+}
+
+
+static ReentrantMonitor* gMon3;
+static int32_t gMonFirst;
+
+static void
+MonitorSyncSanity_thread(void* /*arg*/)
+{
+  gMon3->Enter();
+  gMon3->AssertCurrentThreadIn();
+  if (gMonFirst) {
+    gMonFirst = 0;
+    gMon3->Wait();
+    gMon3->Enter();
+  } else {
+    gMon3->Notify();
+    gMon3->Enter();
+  }
+  gMon3->AssertCurrentThreadIn();
+  gMon3->Exit();
+  gMon3->AssertCurrentThreadIn();
+  gMon3->Exit();
+}
+
+TEST(Synchronization, MonitorSyncSanity)
+{
+  gMon3 = new ReentrantMonitor("monitor::syncsanity");
+
+  for (int32_t i = 0; i < 10000; ++i) {
+    gMonFirst = 1;
+    PRThread* ping = spawn(MonitorSyncSanity_thread, nullptr);
+    PRThread* pong = spawn(MonitorSyncSanity_thread, nullptr);
+    PR_JoinThread(ping);
+    PR_JoinThread(pong);
+  }
+
+  delete gMon3;
+}
+
+//-----------------------------------------------------------------------------
+// Condvar tests
+//
+static Mutex* gCvlock1;
+static CondVar* gCv1;
+static int32_t gCvFirst;
+
+static void
+CondVarSanity_thread(void* /*arg*/)
+{
+  gCvlock1->Lock();
+  gCvlock1->AssertCurrentThreadOwns();
+  if (gCvFirst) {
+    gCvFirst = 0;
+    gCv1->Wait();
+  } else {
+    gCv1->Notify();
+  }
+  gCvlock1->AssertCurrentThreadOwns();
+  gCvlock1->Unlock();
+}
+
+TEST(Synchronization, CondVarSanity)
+{
+  gCvlock1 = new Mutex("cvlock1");
+  gCv1 = new CondVar(*gCvlock1, "cvlock1");
+
+  for (int32_t i = 0; i < 10000; ++i) {
+    gCvFirst = 1;
+    PRThread* ping = spawn(CondVarSanity_thread, nullptr);
+    PRThread* pong = spawn(CondVarSanity_thread, nullptr);
+    PR_JoinThread(ping);
+    PR_JoinThread(pong);
+  }
+
+  delete gCv1;
+  delete gCvlock1;
+}
+
+//-----------------------------------------------------------------------------
+// AutoLock tests
+//
+TEST(Synchronization, AutoLock)
+{
+  Mutex l1("autolock");
+  MutexAutoLock autol1(l1);
+
+  l1.AssertCurrentThreadOwns();
+
+  {
+    Mutex l2("autolock2");
+    MutexAutoLock autol2(l2);
+
+    l1.AssertCurrentThreadOwns();
+    l2.AssertCurrentThreadOwns();
+  }
+
+  l1.AssertCurrentThreadOwns();
+}
+
+//-----------------------------------------------------------------------------
+// AutoUnlock tests
+//
+TEST(Synchronization, AutoUnlock)
+{
+  Mutex l1("autounlock");
+  Mutex l2("autounlock2");
+
+  l1.Lock();
+  l1.AssertCurrentThreadOwns();
+
+  {
+    MutexAutoUnlock autol1(l1);
+    {
+      l2.Lock();
+      l2.AssertCurrentThreadOwns();
+
+      MutexAutoUnlock autol2(l2);
+    }
+    l2.AssertCurrentThreadOwns();
+    l2.Unlock();
+  }
+  l1.AssertCurrentThreadOwns();
+
+  l1.Unlock();
+}
+
+//-----------------------------------------------------------------------------
+// AutoMonitor tests
+//
+TEST(Synchronization, AutoMonitor)
+{
+  ReentrantMonitor m1("automonitor");
+  ReentrantMonitor m2("automonitor2");
+
+  m1.Enter();
+  m1.AssertCurrentThreadIn();
+  {
+    ReentrantMonitorAutoEnter autom1(m1);
+    m1.AssertCurrentThreadIn();
+
+    m2.Enter();
+    m2.AssertCurrentThreadIn();
+    {
+      ReentrantMonitorAutoEnter autom2(m2);
+      m1.AssertCurrentThreadIn();
+      m2.AssertCurrentThreadIn();
+    }
+    m2.AssertCurrentThreadIn();
+    m2.Exit();
+
+    m1.AssertCurrentThreadIn();
+  }
+  m1.AssertCurrentThreadIn();
+  m1.Exit();
+}
diff --git a/xpcom/tests/gtest/TestTArray.cpp b/xpcom/tests/gtest/TestTArray.cpp
new file mode 100644
index 000000000..10e33664f
--- /dev/null
+++ b/xpcom/tests/gtest/TestTArray.cpp
@@ -0,0 +1,206 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsTArray.h"
+#include "gtest/gtest.h"
+
+using namespace mozilla;
+
+namespace TestTArray {
+
+struct Copyable
+{
+  Copyable()
+    : mDestructionCounter(nullptr)
+  {
+  }
+
+  ~Copyable()
+  {
+    if (mDestructionCounter) {
+      (*mDestructionCounter)++;
+    }
+  }
+
+  Copyable(const Copyable&) = default;
+  Copyable& operator=(const Copyable&) = default;
+
+  uint32_t* mDestructionCounter;
+};
+
+struct Movable
+{
+  Movable()
+    : mDestructionCounter(nullptr)
+  {
+  }
+
+  ~Movable()
+  {
+    if (mDestructionCounter) {
+      (*mDestructionCounter)++;
+    }
+  }
+
+  Movable(Movable&& aOther)
+    : mDestructionCounter(aOther.mDestructionCounter)
+  {
+    aOther.mDestructionCounter = nullptr;
+  }
+
+  uint32_t* mDestructionCounter;
+};
+
+} // namespace TestTArray
+
+template<>
+struct nsTArray_CopyChooser<TestTArray::Copyable>
+{
+  typedef nsTArray_CopyWithConstructors<TestTArray::Copyable> Type;
+};
+
+template<>
+struct nsTArray_CopyChooser<TestTArray::Movable>
+{
+  typedef nsTArray_CopyWithConstructors<TestTArray::Movable> Type;
+};
+
+namespace TestTArray {
+
+const nsTArray<int>& DummyArray()
+{
+  static nsTArray<int> sArray;
+  if (sArray.IsEmpty()) {
+    const int data[] = {4, 1, 2, 8};
+    sArray.AppendElements(data, ArrayLength(data));
+  }
+  return sArray;
+}
+
+// This returns an invalid nsTArray with a huge length in order to test that
+// fallible operations actually fail.
+#ifdef DEBUG
+const nsTArray<int>& FakeHugeArray()
+{
+  static nsTArray<int> sArray;
+  if (sArray.IsEmpty()) {
+    sArray.AppendElement();
+    ((nsTArrayHeader*)sArray.DebugGetHeader())->mLength = UINT32_MAX;
+  }
+  return sArray;
+}
+#endif
+
+TEST(TArray, AppendElementsRvalue)
+{
+  nsTArray<int> array;
+
+  nsTArray<int> temp(DummyArray());
+  array.AppendElements(Move(temp));
+  ASSERT_EQ(DummyArray(), array);
+  ASSERT_TRUE(temp.IsEmpty());
+
+  temp = DummyArray();
+  array.AppendElements(Move(temp));
+  nsTArray<int> expected;
+  expected.AppendElements(DummyArray());
+  expected.AppendElements(DummyArray());
+  ASSERT_EQ(expected, array);
+  ASSERT_TRUE(temp.IsEmpty());
+}
+
+TEST(TArray, Assign)
+{
+  nsTArray<int> array;
+  array.Assign(DummyArray());
+  ASSERT_EQ(DummyArray(), array);
+
+  ASSERT_TRUE(array.Assign(DummyArray(), fallible));
+  ASSERT_EQ(DummyArray(), array);
+
+#ifdef DEBUG
+  ASSERT_FALSE(array.Assign(FakeHugeArray(), fallible));
+#endif
+
+  nsTArray<int> array2;
+  array2.Assign(Move(array));
+  ASSERT_TRUE(array.IsEmpty());
+  ASSERT_EQ(DummyArray(), array2);
+}
+
+TEST(TArray, AssignmentOperatorSelfAssignment)
+{
+  nsTArray<int> array;
+  array = DummyArray();
+
+  array = array;
+  ASSERT_EQ(DummyArray(), array);
+  array = Move(array);
+  ASSERT_EQ(DummyArray(), array);
+}
+
+TEST(TArray, CopyOverlappingForwards)
+{
+  nsTArray<Movable> array;
+  const size_t rangeLength = 8;
+  const size_t initialLength = 2 * rangeLength;
+  array.AppendElements(initialLength);
+
+  uint32_t destructionCounters[initialLength];
+  for (uint32_t i = 0; i < initialLength; ++i) {
+    destructionCounters[i] = 0;
+  }
+  for (uint32_t i = 0; i < initialLength; ++i) {
+    array[i].mDestructionCounter = &destructionCounters[i];
+  }
+
+  const size_t removedLength = rangeLength / 2;
+  array.RemoveElementsAt(0, removedLength);
+
+  for (uint32_t i = 0; i < removedLength; ++i) {
+    ASSERT_EQ(destructionCounters[i], 1u);
+  }
+  for (uint32_t i = removedLength; i < initialLength; ++i) {
+    ASSERT_EQ(destructionCounters[i], 0u);
+  }
+}
+
+// The code to copy overlapping regions had a bug in that it wouldn't correctly
+// destroy all over the source elements being copied.
+TEST(TArray, CopyOverlappingBackwards)
+{
+  nsTArray<Copyable> array;
+  const size_t rangeLength = 8;
+  const size_t initialLength = 2 * rangeLength;
+  array.SetCapacity(3 * rangeLength);
+  array.AppendElements(initialLength);
+  // To tickle the bug, we need to copy a source region:
+  //
+  //   ..XXXXX..
+  //
+  // such that it overlaps the destination region:
+  //
+  //   ....XXXXX
+  //
+  // so we are forced to copy back-to-front to ensure correct behavior.
+  // The easiest way to do that is to call InsertElementsAt, which will force
+  // the desired kind of shift.
+  uint32_t destructionCounters[initialLength];
+  for (uint32_t i = 0; i < initialLength; ++i) {
+    destructionCounters[i] = 0;
+  }
+  for (uint32_t i = 0; i < initialLength; ++i) {
+    array[i].mDestructionCounter = &destructionCounters[i];
+  }
+
+  array.InsertElementsAt(0, rangeLength);
+
+  for (uint32_t i = 0; i < initialLength; ++i) {
+    ASSERT_EQ(destructionCounters[i], 1u);
+  }
+}
+
+} // namespace TestTArray
diff --git a/xpcom/tests/gtest/TestTArray2.cpp b/xpcom/tests/gtest/TestTArray2.cpp
new file mode 100644
index 000000000..421927104
--- /dev/null
+++ b/xpcom/tests/gtest/TestTArray2.cpp
@@ -0,0 +1,1033 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/Unused.h"
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <iostream>
+#include "nsTArray.h"
+#include "nsAutoPtr.h"
+#include "nsString.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsDirectoryServiceUtils.h"
+#include "nsComponentManagerUtils.h"
+#include "nsXPCOM.h"
+#include "nsIFile.h"
+
+#include "gtest/gtest.h"
+
+using namespace mozilla;
+
+namespace TestTArray {
+
+// Define this so we can use test_basic_array in test_comptr_array
+template <class T>
+inline bool operator<(const nsCOMPtr<T>& lhs, const nsCOMPtr<T>& rhs) {
+  return lhs.get() < rhs.get();
+}
+
+//----
+
+template <class ElementType>
+static bool test_basic_array(ElementType *data,
+                             size_t dataLen,
+                             const ElementType& extra) {
+  nsTArray<ElementType> ary;
+  ary.AppendElements(data, dataLen);
+  if (ary.Length() != dataLen) {
+    return false;
+  }
+  if (!(ary == ary)) {
+    return false;
+  }
+  size_t i;
+  for (i = 0; i < ary.Length(); ++i) {
+    if (ary[i] != data[i])
+      return false;
+  }
+  for (i = 0; i < ary.Length(); ++i) {
+    if (ary.SafeElementAt(i, extra) != data[i])
+      return false;
+  }
+  if (ary.SafeElementAt(ary.Length(), extra) != extra ||
+      ary.SafeElementAt(ary.Length() * 10, extra) != extra)
+    return false;
+  // ensure sort results in ascending order
+  ary.Sort();
+  size_t j = 0, k = ary.IndexOfFirstElementGt(extra);
+  if (k != 0 && ary[k-1] == extra)
+    return false;
+  for (i = 0; i < ary.Length(); ++i) {
+    k = ary.IndexOfFirstElementGt(ary[i]);
+    if (k == 0 || ary[k-1] != ary[i])
+      return false;
+    if (k < j)
+      return false;
+    j = k;
+  }
+  for (i = ary.Length(); --i; ) {
+    if (ary[i] < ary[i - 1])
+      return false;
+    if (ary[i] == ary[i - 1])
+      ary.RemoveElementAt(i);
+  }
+  if (!(ary == ary)) {
+    return false;
+  }
+  for (i = 0; i < ary.Length(); ++i) {
+    if (ary.BinaryIndexOf(ary[i]) != i)
+      return false;
+  }
+  if (ary.BinaryIndexOf(extra) != ary.NoIndex)
+    return false;
+  size_t oldLen = ary.Length();
+  ary.RemoveElement(data[dataLen / 2]);
+  if (ary.Length() != (oldLen - 1))
+    return false;
+  if (!(ary == ary))
+    return false;
+
+  size_t index = ary.Length() / 2;
+  if (!ary.InsertElementAt(index, extra))
+    return false;
+  if (!(ary == ary))
+    return false;
+  if (ary[index] != extra)
+    return false;
+  if (ary.IndexOf(extra) == ary.NoIndex)
+    return false;
+  if (ary.LastIndexOf(extra) == ary.NoIndex)
+    return false;
+  // ensure proper searching
+  if (ary.IndexOf(extra) > ary.LastIndexOf(extra))
+    return false;
+  if (ary.IndexOf(extra, index) != ary.LastIndexOf(extra, index))
+    return false;
+
+  nsTArray<ElementType> copy(ary);
+  if (!(ary == copy))
+    return false;
+  for (i = 0; i < copy.Length(); ++i) {
+    if (ary[i] != copy[i])
+      return false;
+  }
+  if (!ary.AppendElements(copy))
+    return false;
+  size_t cap = ary.Capacity();
+  ary.RemoveElementsAt(copy.Length(), copy.Length());
+  ary.Compact();
+  if (ary.Capacity() == cap)
+    return false;
+
+  ary.Clear();
+  if (ary.IndexOf(extra) != ary.NoIndex)
+    return false;
+  if (ary.LastIndexOf(extra) != ary.NoIndex)
+    return false;
+
+  ary.Clear();
+  if (!ary.IsEmpty() || ary.Elements() == nullptr)
+    return false;
+  if (!(ary == nsTArray<ElementType>()))
+    return false;
+  if (ary == copy)
+    return false;
+  if (ary.SafeElementAt(0, extra) != extra ||
+      ary.SafeElementAt(10, extra) != extra)
+    return false;
+
+  ary = copy;
+  if (!(ary == copy))
+    return false;
+  for (i = 0; i < copy.Length(); ++i) {
+    if (ary[i] != copy[i])
+      return false;
+  }
+
+  if (!ary.InsertElementsAt(0, copy))
+    return false;
+  if (ary == copy)
+    return false;
+  ary.RemoveElementsAt(0, copy.Length());
+  for (i = 0; i < copy.Length(); ++i) {
+    if (ary[i] != copy[i])
+      return false;
+  }
+
+  // These shouldn't crash!
+  nsTArray<ElementType> empty;
+  ary.AppendElements(reinterpret_cast<ElementType *>(0), 0);
+  ary.AppendElements(empty);
+
+  // See bug 324981
+  ary.RemoveElement(extra);
+  ary.RemoveElement(extra);
+
+  return true;
+}
+
+TEST(TArray, test_int_array) {
+  int data[] = {4,6,8,2,4,1,5,7,3};
+  ASSERT_TRUE(test_basic_array(data, ArrayLength(data), int(14)));
+}
+
+TEST(TArray, test_int64_array) {
+  int64_t data[] = {4,6,8,2,4,1,5,7,3};
+  ASSERT_TRUE(test_basic_array(data, ArrayLength(data), int64_t(14)));
+}
+
+TEST(TArray, test_char_array) {
+  char data[] = {4,6,8,2,4,1,5,7,3};
+  ASSERT_TRUE(test_basic_array(data, ArrayLength(data), char(14)));
+}
+
+TEST(TArray, test_uint32_array) {
+  uint32_t data[] = {4,6,8,2,4,1,5,7,3};
+  ASSERT_TRUE(test_basic_array(data, ArrayLength(data), uint32_t(14)));
+}
+
+//----
+
+class Object {
+  public:
+    Object() : mNum(0) {
+    }
+    Object(const char *str, uint32_t num) : mStr(str), mNum(num) {
+    }
+    Object(const Object& other) : mStr(other.mStr), mNum(other.mNum) {
+    }
+    ~Object() {}
+
+    Object& operator=(const Object& other) {
+      mStr = other.mStr;
+      mNum = other.mNum;
+      return *this;
+    }
+
+    bool operator==(const Object& other) const {
+      return mStr == other.mStr && mNum == other.mNum;
+    }
+
+    bool operator<(const Object& other) const {
+      // sort based on mStr only
+      return mStr.Compare(other.mStr.get()) < 0;
+    }
+
+    const char *Str() const { return mStr.get(); }
+    uint32_t Num() const { return mNum; }
+
+  private:
+    nsCString mStr;
+    uint32_t  mNum;
+};
+
+TEST(TArray, test_object_array) {
+  nsTArray<Object> objArray;
+  const char kdata[] = "hello world";
+  size_t i;
+  for (i = 0; i < ArrayLength(kdata); ++i) {
+    char x[] = {kdata[i],'\0'};
+    ASSERT_TRUE(objArray.AppendElement(Object(x, i)));
+  }
+  for (i = 0; i < ArrayLength(kdata); ++i) {
+    ASSERT_EQ(objArray[i].Str()[0], kdata[i]);
+    ASSERT_EQ(objArray[i].Num(), i);
+  }
+  objArray.Sort();
+  const char ksorted[] = "\0 dehllloorw";
+  for (i = 0; i < ArrayLength(kdata)-1; ++i) {
+    ASSERT_EQ(objArray[i].Str()[0], ksorted[i]);
+  }
+}
+
+class Countable {
+  static int sCount;
+
+  public:
+    Countable()
+    {
+      sCount++;
+    }
+
+    Countable(const Countable& aOther)
+    {
+      sCount++;
+    }
+
+    static int Count() { return sCount; }
+};
+
+class Moveable {
+  static int sCount;
+
+  public:
+    Moveable()
+    {
+      sCount++;
+    }
+
+    Moveable(const Moveable& aOther)
+    {
+      sCount++;
+    }
+
+    Moveable(Moveable&& aOther)
+    {
+      // Do not increment sCount
+    }
+
+    static int Count() { return sCount; }
+};
+
+/* static */ int Countable::sCount = 0;
+/* static */ int Moveable::sCount = 0;
+
+static nsTArray<int> returns_by_value() {
+  nsTArray<int> result;
+  return result;
+}
+
+TEST(TArray, test_return_by_value) {
+  nsTArray<int> result = returns_by_value();
+  ASSERT_TRUE(true); // This is just a compilation test.
+}
+
+TEST(TArray, test_move_array) {
+  nsTArray<Countable> countableArray;
+  uint32_t i;
+  for (i = 0; i < 4; ++i) {
+    ASSERT_TRUE(countableArray.AppendElement(Countable()));
+  }
+
+  ASSERT_EQ(Countable::Count(), 8);
+
+  const nsTArray<Countable>& constRefCountableArray = countableArray;
+
+  ASSERT_EQ(Countable::Count(), 8);
+
+  nsTArray<Countable> copyCountableArray(constRefCountableArray);
+
+  ASSERT_EQ(Countable::Count(), 12);
+
+  nsTArray<Countable>&& moveRefCountableArray = Move(countableArray);
+  moveRefCountableArray.Length(); // Make compilers happy.
+
+  ASSERT_EQ(Countable::Count(), 12);
+
+  nsTArray<Countable> movedCountableArray(Move(countableArray));
+
+  ASSERT_EQ(Countable::Count(), 12);
+
+  // Test ctor
+  FallibleTArray<Countable> differentAllocatorCountableArray(Move(copyCountableArray));
+  // operator=
+  copyCountableArray = Move(differentAllocatorCountableArray);
+  differentAllocatorCountableArray = Move(copyCountableArray);
+  // And the other ctor
+  nsTArray<Countable> copyCountableArray2(Move(differentAllocatorCountableArray));
+  // with auto
+  AutoTArray<Countable, 3> autoCountableArray(Move(copyCountableArray2));
+  // operator=
+  copyCountableArray2 = Move(autoCountableArray);
+  // Mix with FallibleTArray
+  FallibleTArray<Countable> differentAllocatorCountableArray2(Move(copyCountableArray2));
+  AutoTArray<Countable, 4> autoCountableArray2(Move(differentAllocatorCountableArray2));
+  differentAllocatorCountableArray2 = Move(autoCountableArray2);
+
+  ASSERT_EQ(Countable::Count(), 12);
+
+  nsTArray<Moveable> moveableArray;
+  for (i = 0; i < 4; ++i) {
+    ASSERT_TRUE(moveableArray.AppendElement(Moveable()));
+  }
+
+  ASSERT_EQ(Moveable::Count(), 4);
+
+  const nsTArray<Moveable>& constRefMoveableArray = moveableArray;
+
+  ASSERT_EQ(Moveable::Count(), 4);
+
+  nsTArray<Moveable> copyMoveableArray(constRefMoveableArray);
+
+  ASSERT_EQ(Moveable::Count(), 8);
+
+  nsTArray<Moveable>&& moveRefMoveableArray = Move(moveableArray);
+  moveRefMoveableArray.Length(); // Make compilers happy.
+
+  ASSERT_EQ(Moveable::Count(), 8);
+
+  nsTArray<Moveable> movedMoveableArray(Move(moveableArray));
+
+  ASSERT_EQ(Moveable::Count(), 8);
+
+  // Test ctor
+  FallibleTArray<Moveable> differentAllocatorMoveableArray(Move(copyMoveableArray));
+  // operator=
+  copyMoveableArray = Move(differentAllocatorMoveableArray);
+  differentAllocatorMoveableArray = Move(copyMoveableArray);
+  // And the other ctor
+  nsTArray<Moveable> copyMoveableArray2(Move(differentAllocatorMoveableArray));
+  // with auto
+  AutoTArray<Moveable, 3> autoMoveableArray(Move(copyMoveableArray2));
+  // operator=
+  copyMoveableArray2 = Move(autoMoveableArray);
+  // Mix with FallibleTArray
+  FallibleTArray<Moveable> differentAllocatorMoveableArray2(Move(copyMoveableArray2));
+  AutoTArray<Moveable, 4> autoMoveableArray2(Move(differentAllocatorMoveableArray2));
+  differentAllocatorMoveableArray2 = Move(autoMoveableArray2);
+
+  ASSERT_EQ(Moveable::Count(), 8);
+}
+
+//----
+
+TEST(TArray, test_string_array) {
+  nsTArray<nsCString> strArray;
+  const char kdata[] = "hello world";
+  size_t i;
+  for (i = 0; i < ArrayLength(kdata); ++i) {
+    nsCString str;
+    str.Assign(kdata[i]);
+    ASSERT_TRUE(strArray.AppendElement(str));
+  }
+  for (i = 0; i < ArrayLength(kdata); ++i) {
+    ASSERT_EQ(strArray[i].CharAt(0), kdata[i]);
+  }
+
+  const char kextra[] = "foo bar";
+  size_t oldLen = strArray.Length();
+  ASSERT_TRUE(strArray.AppendElement(kextra));
+  strArray.RemoveElement(kextra);
+  ASSERT_EQ(oldLen, strArray.Length());
+
+  ASSERT_EQ(strArray.IndexOf("e"), size_t(1));
+
+  strArray.Sort();
+  const char ksorted[] = "\0 dehllloorw";
+  for (i = ArrayLength(kdata); i--; ) {
+    ASSERT_EQ(strArray[i].CharAt(0), ksorted[i]);
+    if (i > 0 && strArray[i] == strArray[i - 1])
+      strArray.RemoveElementAt(i);
+  }
+  for (i = 0; i < strArray.Length(); ++i) {
+    ASSERT_EQ(strArray.BinaryIndexOf(strArray[i]), i);
+  }
+  auto no_index = strArray.NoIndex; // Fixes gtest compilation error
+  ASSERT_EQ(strArray.BinaryIndexOf(EmptyCString()), no_index);
+
+  nsCString rawArray[MOZ_ARRAY_LENGTH(kdata) - 1];
+  for (i = 0; i < ArrayLength(rawArray); ++i)
+    rawArray[i].Assign(kdata + i);  // substrings of kdata
+
+  ASSERT_TRUE(test_basic_array(rawArray, ArrayLength(rawArray),
+                               nsCString("foopy")));
+}
+
+//----
+
+typedef nsCOMPtr<nsIFile> FilePointer;
+
+class nsFileNameComparator {
+  public:
+    bool Equals(const FilePointer &a, const char *b) const {
+      nsAutoCString name;
+      a->GetNativeLeafName(name);
+      return name.Equals(b);
+    }
+};
+
+TEST(TArray, test_comptr_array) {
+  FilePointer tmpDir;
+  NS_GetSpecialDirectory(NS_OS_TEMP_DIR, getter_AddRefs(tmpDir));
+  ASSERT_TRUE(tmpDir);
+  const char *kNames[] = {
+    "foo.txt", "bar.html", "baz.gif"
+  };
+  nsTArray<FilePointer> fileArray;
+  size_t i;
+  for (i = 0; i < ArrayLength(kNames); ++i) {
+    FilePointer f;
+    tmpDir->Clone(getter_AddRefs(f));
+    ASSERT_TRUE(f);
+    ASSERT_FALSE(NS_FAILED(f->AppendNative(nsDependentCString(kNames[i]))));
+    fileArray.AppendElement(f);
+  }
+
+  ASSERT_EQ(fileArray.IndexOf(kNames[1], 0, nsFileNameComparator()), size_t(1));
+
+  // It's unclear what 'operator<' means for nsCOMPtr, but whatever...
+  ASSERT_TRUE(test_basic_array(fileArray.Elements(), fileArray.Length(),
+                               tmpDir));
+}
+
+//----
+
+class RefcountedObject {
+  public:
+    RefcountedObject() : rc(0) {}
+    void AddRef() {
+      ++rc;
+    }
+    void Release() {
+      if (--rc == 0)
+        delete this;
+    }
+    ~RefcountedObject() {}
+  private:
+    int32_t rc;
+};
+
+TEST(TArray, test_refptr_array) {
+  nsTArray< RefPtr<RefcountedObject> > objArray;
+
+  RefcountedObject *a = new RefcountedObject(); a->AddRef();
+  RefcountedObject *b = new RefcountedObject(); b->AddRef();
+  RefcountedObject *c = new RefcountedObject(); c->AddRef();
+
+  objArray.AppendElement(a);
+  objArray.AppendElement(b);
+  objArray.AppendElement(c);
+
+  ASSERT_EQ(objArray.IndexOf(b), size_t(1));
+
+  a->Release();
+  b->Release();
+  c->Release();
+}
+
+//----
+
+TEST(TArray, test_ptrarray) {
+  nsTArray<uint32_t*> ary;
+  ASSERT_EQ(ary.SafeElementAt(0), nullptr);
+  ASSERT_EQ(ary.SafeElementAt(1000), nullptr);
+
+  uint32_t a = 10;
+  ary.AppendElement(&a);
+  ASSERT_EQ(*ary[0], a);
+  ASSERT_EQ(*ary.SafeElementAt(0), a);
+
+  nsTArray<const uint32_t*> cary;
+  ASSERT_EQ(cary.SafeElementAt(0), nullptr);
+  ASSERT_EQ(cary.SafeElementAt(1000), nullptr);
+
+  const uint32_t b = 14;
+  cary.AppendElement(&a);
+  cary.AppendElement(&b);
+  ASSERT_EQ(*cary[0], a);
+  ASSERT_EQ(*cary[1], b);
+  ASSERT_EQ(*cary.SafeElementAt(0), a);
+  ASSERT_EQ(*cary.SafeElementAt(1), b);
+}
+
+//----
+
+// This test relies too heavily on the existence of DebugGetHeader to be
+// useful in non-debug builds.
+#ifdef DEBUG
+TEST(TArray, test_autoarray) {
+  uint32_t data[] = {4,6,8,2,4,1,5,7,3};
+  AutoTArray<uint32_t, MOZ_ARRAY_LENGTH(data)> array;
+
+  void* hdr = array.DebugGetHeader();
+  ASSERT_NE(hdr, nsTArray<uint32_t>().DebugGetHeader());
+  ASSERT_NE(hdr, (AutoTArray<uint32_t, MOZ_ARRAY_LENGTH(data)>().DebugGetHeader()));
+
+  array.AppendElement(1u);
+  ASSERT_EQ(hdr, array.DebugGetHeader());
+
+  array.RemoveElement(1u);
+  array.AppendElements(data, ArrayLength(data));
+  ASSERT_EQ(hdr, array.DebugGetHeader());
+
+  array.AppendElement(2u);
+  ASSERT_NE(hdr, array.DebugGetHeader());
+
+  array.Clear();
+  array.Compact();
+  ASSERT_EQ(hdr, array.DebugGetHeader());
+  array.AppendElements(data, ArrayLength(data));
+  ASSERT_EQ(hdr, array.DebugGetHeader());
+
+  nsTArray<uint32_t> array2;
+  void* emptyHdr = array2.DebugGetHeader();
+  array.SwapElements(array2);
+  ASSERT_NE(emptyHdr, array.DebugGetHeader());
+  ASSERT_NE(hdr, array2.DebugGetHeader());
+  size_t i;
+  for (i = 0; i < ArrayLength(data); ++i) {
+    ASSERT_EQ(array2[i], data[i]);
+  }
+  ASSERT_TRUE(array.IsEmpty());
+
+  array.Compact();
+  array.AppendElements(data, ArrayLength(data));
+  uint32_t data3[] = {5, 7, 11};
+  AutoTArray<uint32_t, MOZ_ARRAY_LENGTH(data3)> array3;
+  array3.AppendElements(data3, ArrayLength(data3));
+  array.SwapElements(array3);
+  for (i = 0; i < ArrayLength(data); ++i) {
+    ASSERT_EQ(array3[i], data[i]);
+  }
+  for (i = 0; i < ArrayLength(data3); ++i) {
+    ASSERT_EQ(array[i], data3[i]);
+  }
+}
+#endif
+
+//----
+
+// IndexOf used to potentially scan beyond the end of the array.  Test for
+// this incorrect behavior by adding a value (5), removing it, then seeing
+// if IndexOf finds it.
+TEST(TArray, test_indexof) {
+  nsTArray<int> array;
+  array.AppendElement(0);
+  // add and remove the 5
+  array.AppendElement(5);
+  array.RemoveElementAt(1);
+  // we should not find the 5!
+  auto no_index = array.NoIndex; // Fixes gtest compilation error.
+  ASSERT_EQ(array.IndexOf(5, 1), no_index);
+}
+
+//----
+
+template <class Array>
+static bool is_heap(const Array& ary, size_t len) {
+  size_t index = 1;
+  while (index < len) {
+    if (ary[index] > ary[(index - 1) >> 1])
+      return false;
+    index++;
+  }
+  return true;
+} 
+
+//----
+
+// An array |arr| is using its auto buffer if |&arr < arr.Elements()| and
+// |arr.Elements() - &arr| is small.
+
+#define IS_USING_AUTO(arr) \
+  ((uintptr_t) &(arr) < (uintptr_t) arr.Elements() && \
+   ((ptrdiff_t)arr.Elements() - (ptrdiff_t)&arr) <= 16)
+
+#define CHECK_IS_USING_AUTO(arr) \
+  do {                                                    \
+    ASSERT_TRUE(IS_USING_AUTO(arr));                      \
+  } while(0)
+
+#define CHECK_NOT_USING_AUTO(arr) \
+  do {                                                    \
+    ASSERT_FALSE(IS_USING_AUTO(arr));                     \
+  } while(0)
+
+#define CHECK_USES_SHARED_EMPTY_HDR(arr) \
+  do {                                                    \
+    nsTArray<int> _empty;                                 \
+    ASSERT_EQ(_empty.Elements(), arr.Elements());         \
+  } while(0)
+
+#define CHECK_EQ_INT(actual, expected) \
+  do {                                                                       \
+    ASSERT_EQ((actual), (expected));                                         \
+  } while(0)
+
+#define CHECK_ARRAY(arr, data) \
+  do {                                                          \
+    CHECK_EQ_INT((arr).Length(), (size_t)ArrayLength(data));  \
+    for (size_t _i = 0; _i < ArrayLength(data); _i++) {       \
+      CHECK_EQ_INT((arr)[_i], (data)[_i]);                      \
+    }                                                           \
+  } while(0)
+
+TEST(TArray, test_swap) {
+  // Test nsTArray::SwapElements.  Unfortunately there are many cases.
+  int data1[] = {8, 6, 7, 5};
+  int data2[] = {3, 0, 9};
+
+  // Swap two auto arrays.
+  {
+    AutoTArray<int, 8> a;
+    AutoTArray<int, 6> b;
+
+    a.AppendElements(data1, ArrayLength(data1));
+    b.AppendElements(data2, ArrayLength(data2));
+    CHECK_IS_USING_AUTO(a);
+    CHECK_IS_USING_AUTO(b);
+
+    a.SwapElements(b);
+
+    CHECK_IS_USING_AUTO(a);
+    CHECK_IS_USING_AUTO(b);
+    CHECK_ARRAY(a, data2);
+    CHECK_ARRAY(b, data1);
+  }
+
+  // Swap two auto arrays -- one whose data lives on the heap, the other whose
+  // data lives on the stack -- which each fits into the other's auto storage.
+  {
+    AutoTArray<int, 3> a;
+    AutoTArray<int, 3> b;
+
+    a.AppendElements(data1, ArrayLength(data1));
+    a.RemoveElementAt(3);
+    b.AppendElements(data2, ArrayLength(data2));
+
+    // Here and elsewhere, we assert that if we start with an auto array
+    // capable of storing N elements, we store N+1 elements into the array, and
+    // then we remove one element, that array is still not using its auto
+    // buffer.
+    //
+    // This isn't at all required by the TArray API. It would be fine if, when
+    // we shrink back to N elements, the TArray frees its heap storage and goes
+    // back to using its stack storage.  But we assert here as a check that the
+    // test does what we expect.  If the TArray implementation changes, just
+    // change the failing assertions.
+    CHECK_NOT_USING_AUTO(a);
+
+    // This check had better not change, though.
+    CHECK_IS_USING_AUTO(b);
+
+    a.SwapElements(b);
+
+    CHECK_IS_USING_AUTO(b);
+    CHECK_ARRAY(a, data2);
+    int expectedB[] = {8, 6, 7};
+    CHECK_ARRAY(b, expectedB);
+  }
+
+  // Swap two auto arrays which are using heap storage such that one fits into
+  // the other's auto storage, but the other needs to stay on the heap.
+  {
+    AutoTArray<int, 3> a;
+    AutoTArray<int, 2> b;
+    a.AppendElements(data1, ArrayLength(data1));
+    a.RemoveElementAt(3);
+
+    b.AppendElements(data2, ArrayLength(data2));
+    b.RemoveElementAt(2);
+
+    CHECK_NOT_USING_AUTO(a);
+    CHECK_NOT_USING_AUTO(b);
+
+    a.SwapElements(b);
+
+    CHECK_NOT_USING_AUTO(b);
+
+    int expected1[] = {3, 0};
+    int expected2[] = {8, 6, 7};
+
+    CHECK_ARRAY(a, expected1);
+    CHECK_ARRAY(b, expected2);
+  }
+
+  // Swap two arrays, neither of which fits into the other's auto-storage.
+  {
+    AutoTArray<int, 1> a;
+    AutoTArray<int, 3> b;
+
+    a.AppendElements(data1, ArrayLength(data1));
+    b.AppendElements(data2, ArrayLength(data2));
+
+    a.SwapElements(b);
+
+    CHECK_ARRAY(a, data2);
+    CHECK_ARRAY(b, data1);
+  }
+
+  // Swap an empty nsTArray with a non-empty AutoTArray.
+  {
+    nsTArray<int> a;
+    AutoTArray<int, 3> b;
+
+    b.AppendElements(data2, ArrayLength(data2));
+    CHECK_IS_USING_AUTO(b);
+
+    a.SwapElements(b);
+
+    CHECK_ARRAY(a, data2);
+    CHECK_EQ_INT(b.Length(), size_t(0));
+    CHECK_IS_USING_AUTO(b);
+  }
+
+  // Swap two big auto arrays.
+  {
+    const unsigned size = 8192;
+    AutoTArray<unsigned, size> a;
+    AutoTArray<unsigned, size> b;
+
+    for (unsigned i = 0; i < size; i++) {
+      a.AppendElement(i);
+      b.AppendElement(i + 1);
+    }
+
+    CHECK_IS_USING_AUTO(a);
+    CHECK_IS_USING_AUTO(b);
+
+    a.SwapElements(b);
+
+    CHECK_IS_USING_AUTO(a);
+    CHECK_IS_USING_AUTO(b);
+
+    CHECK_EQ_INT(a.Length(), size_t(size));
+    CHECK_EQ_INT(b.Length(), size_t(size));
+
+    for (unsigned i = 0; i < size; i++) {
+      CHECK_EQ_INT(a[i], i + 1);
+      CHECK_EQ_INT(b[i], i);
+    }
+  }
+
+  // Swap two arrays and make sure that their capacities don't increase
+  // unnecessarily.
+  {
+    nsTArray<int> a;
+    nsTArray<int> b;
+    b.AppendElements(data2, ArrayLength(data2));
+
+    CHECK_EQ_INT(a.Capacity(), size_t(0));
+    size_t bCapacity = b.Capacity();
+
+    a.SwapElements(b);
+
+    // Make sure that we didn't increase the capacity of either array.
+    CHECK_ARRAY(a, data2);
+    CHECK_EQ_INT(b.Length(), size_t(0));
+    CHECK_EQ_INT(b.Capacity(), size_t(0));
+    CHECK_EQ_INT(a.Capacity(), bCapacity);
+  }
+
+  // Swap an auto array with a TArray, then clear the auto array and make sure
+  // it doesn't forget the fact that it has an auto buffer.
+  {
+    nsTArray<int> a;
+    AutoTArray<int, 3> b;
+
+    a.AppendElements(data1, ArrayLength(data1));
+
+    a.SwapElements(b);
+
+    CHECK_EQ_INT(a.Length(), size_t(0));
+    CHECK_ARRAY(b, data1);
+
+    b.Clear();
+
+    CHECK_USES_SHARED_EMPTY_HDR(a);
+    CHECK_IS_USING_AUTO(b);
+  }
+
+  // Same thing as the previous test, but with more auto arrays.
+  {
+    AutoTArray<int, 16> a;
+    AutoTArray<int, 3> b;
+
+    a.AppendElements(data1, ArrayLength(data1));
+
+    a.SwapElements(b);
+
+    CHECK_EQ_INT(a.Length(), size_t(0));
+    CHECK_ARRAY(b, data1);
+
+    b.Clear();
+
+    CHECK_IS_USING_AUTO(a);
+    CHECK_IS_USING_AUTO(b);
+  }
+
+  // Swap an empty nsTArray and an empty AutoTArray.
+  {
+    AutoTArray<int, 8> a;
+    nsTArray<int> b;
+
+    a.SwapElements(b);
+
+    CHECK_IS_USING_AUTO(a);
+    CHECK_NOT_USING_AUTO(b);
+    CHECK_EQ_INT(a.Length(), size_t(0));
+    CHECK_EQ_INT(b.Length(), size_t(0));
+  }
+
+  // Swap empty auto array with non-empty AutoTArray using malloc'ed storage.
+  // I promise, all these tests have a point.
+  {
+    AutoTArray<int, 2> a;
+    AutoTArray<int, 1> b;
+
+    a.AppendElements(data1, ArrayLength(data1));
+
+    a.SwapElements(b);
+
+    CHECK_IS_USING_AUTO(a);
+    CHECK_NOT_USING_AUTO(b);
+    CHECK_ARRAY(b, data1);
+    CHECK_EQ_INT(a.Length(), size_t(0));
+  }
+}
+
+// Bug 1171296: Disabled on andoid due to crashes.
+#if !defined(ANDROID)
+TEST(TArray, test_fallible)
+{
+  // Test that FallibleTArray works properly; that is, it never OOMs, but
+  // instead eventually returns false.
+  //
+  // This test is only meaningful on 32-bit systems.  On a 64-bit system, we
+  // might never OOM.
+  if (sizeof(void*) > 4) {
+    ASSERT_TRUE(true);
+    return;
+  }
+
+  // Allocate a bunch of 128MB arrays.  Larger allocations will fail on some
+  // platforms without actually hitting OOM.
+  //
+  // 36 * 128MB > 4GB, so we should definitely OOM by the 36th array.
+  const unsigned numArrays = 36;
+  FallibleTArray<char> arrays[numArrays];
+  bool oomed = false;
+  for (size_t i = 0; i < numArrays; i++) {
+    // SetCapacity allocates the requested capacity + a header, and we want to
+    // avoid allocating more than 128MB overall because of the size padding it
+    // will cause, which depends on allocator behavior, so use 128MB - an
+    // arbitrary size larger than the array header, so that chances are good
+    // that allocations will always be 128MB.
+    bool success = arrays[i].SetCapacity(128 * 1024 * 1024 - 1024, fallible);
+    if (!success) {
+      // We got our OOM.  Check that it didn't come too early.
+      oomed = true;
+      ASSERT_GE(i, size_t(8)) << "Got OOM on iteration " << i << ". Too early!";
+    }
+  }
+
+  ASSERT_TRUE(oomed) << "Didn't OOM or crash?  nsTArray::SetCapacity"
+                        "must be lying.";
+}
+#endif
+
+TEST(TArray, test_conversion_operator) {
+  FallibleTArray<int> f;
+  const FallibleTArray<int> fconst;
+
+  InfallibleTArray<int> i;
+  const InfallibleTArray<int> iconst;
+
+  nsTArray<int> t;
+  const nsTArray<int> tconst;
+  AutoTArray<int, 8> tauto;
+  const AutoTArray<int, 8> tautoconst;
+
+#define CHECK_ARRAY_CAST(type)                        \
+  do {                                                \
+    const type<int>& z1 = f;                          \
+    ASSERT_EQ((void*)&z1, (void*)&f);                 \
+    const type<int>& z2 = fconst;                     \
+    ASSERT_EQ((void*)&z2, (void*)&fconst);            \
+    const type<int>& z5 = i;                          \
+    ASSERT_EQ((void*)&z5, (void*)&i);                 \
+    const type<int>& z6 = iconst;                     \
+    ASSERT_EQ((void*)&z6, (void*)&iconst);            \
+    const type<int>& z9 = t;                          \
+    ASSERT_EQ((void*)&z9, (void*)&t);                 \
+    const type<int>& z10 = tconst;                    \
+    ASSERT_EQ((void*)&z10, (void*)&tconst);           \
+    const type<int>& z11 = tauto;                     \
+    ASSERT_EQ((void*)&z11, (void*)&tauto);            \
+    const type<int>& z12 = tautoconst;                \
+    ASSERT_EQ((void*)&z12, (void*)&tautoconst);       \
+  } while (0)
+
+  CHECK_ARRAY_CAST(FallibleTArray);
+  CHECK_ARRAY_CAST(InfallibleTArray);
+  CHECK_ARRAY_CAST(nsTArray);
+
+#undef CHECK_ARRAY_CAST
+}
+
+template<class T>
+struct BufAccessor : public T
+{
+  void* GetHdr() { return T::mHdr; }
+};
+
+TEST(TArray, test_SetLengthAndRetainStorage_no_ctor) {
+  // 1050 because sizeof(int)*1050 is more than a page typically.
+  const int N = 1050;
+  FallibleTArray<int> f;
+
+  InfallibleTArray<int> i;
+
+  nsTArray<int> t;
+  AutoTArray<int, N> tauto;
+
+#define LPAREN (
+#define RPAREN )
+#define FOR_EACH(pre, post)                                    \
+  do {                                                         \
+    pre f post;                                                \
+    pre i post;                                                \
+    pre t post;                                                \
+    pre tauto post;                                            \
+  } while (0)
+
+  // Setup test arrays.
+  FOR_EACH(; Unused << , .SetLength(N, fallible));
+  for (int n = 0; n < N; ++n) {
+    FOR_EACH(;, [n] = n);
+  }
+
+  void* initial_Hdrs[] = {
+    static_cast<BufAccessor<FallibleTArray<int> >&>(f).GetHdr(),
+    static_cast<BufAccessor<InfallibleTArray<int> >&>(i).GetHdr(),
+    static_cast<BufAccessor<nsTArray<int> >&>(t).GetHdr(),
+    static_cast<BufAccessor<AutoTArray<int, N> >&>(tauto).GetHdr(),
+    nullptr
+  };
+
+  // SetLengthAndRetainStorage(n), should NOT overwrite memory when T hasn't
+  // a default constructor.
+  FOR_EACH(;, .SetLengthAndRetainStorage(8));
+  FOR_EACH(;, .SetLengthAndRetainStorage(12));
+  for (int n = 0; n < 12; ++n) {
+    ASSERT_EQ(f[n], n);
+    ASSERT_EQ(i[n], n);
+    ASSERT_EQ(t[n], n);
+    ASSERT_EQ(tauto[n], n);
+  }
+  FOR_EACH(;, .SetLengthAndRetainStorage(0));
+  FOR_EACH(;, .SetLengthAndRetainStorage(N));
+  for (int n = 0; n < N; ++n) {
+    ASSERT_EQ(f[n], n);
+    ASSERT_EQ(i[n], n);
+    ASSERT_EQ(t[n], n);
+    ASSERT_EQ(tauto[n], n);
+  }
+
+  void* current_Hdrs[] = {
+    static_cast<BufAccessor<FallibleTArray<int> >&>(f).GetHdr(),
+    static_cast<BufAccessor<InfallibleTArray<int> >&>(i).GetHdr(),
+    static_cast<BufAccessor<nsTArray<int> >&>(t).GetHdr(),
+    static_cast<BufAccessor<AutoTArray<int, N> >&>(tauto).GetHdr(),
+    nullptr
+  };
+
+  // SetLengthAndRetainStorage(n) should NOT have reallocated the internal
+  // memory.
+  ASSERT_EQ(sizeof(initial_Hdrs), sizeof(current_Hdrs));
+  for (size_t n = 0; n < sizeof(current_Hdrs) / sizeof(current_Hdrs[0]); ++n) {
+    ASSERT_EQ(current_Hdrs[n], initial_Hdrs[n]);
+  }
+
+
+#undef FOR_EACH
+#undef LPAREN
+#undef RPAREN
+}
+
+} // namespace TestTArray
diff --git a/xpcom/tests/gtest/TestTextFormatter.cpp b/xpcom/tests/gtest/TestTextFormatter.cpp
new file mode 100644
index 000000000..c98b766cc
--- /dev/null
+++ b/xpcom/tests/gtest/TestTextFormatter.cpp
@@ -0,0 +1,34 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsTextFormatter.h"
+#include "nsString.h"
+#include "gtest/gtest.h"
+
+TEST(TextFormatter, Tests)
+{
+  nsAutoString fmt(NS_LITERAL_STRING("%3$s %4$S %1$d %2$d %2$d %3$s"));
+  char utf8[] = "Hello";
+  char16_t ucs2[]={'W', 'o', 'r', 'l', 'd', 0x4e00, 0xAc00, 0xFF45, 0x0103, 0x00};
+  int d=3;
+
+  char16_t buf[256];
+  nsTextFormatter::snprintf(buf, 256, fmt.get(), d, 333, utf8, ucs2);
+  nsAutoString out(buf);
+  ASSERT_STREQ("Hello World", NS_LossyConvertUTF16toASCII(out).get());
+
+  const char16_t *uout = out.get();
+  const char16_t expected[] = {0x48, 0x65, 0x6C, 0x6C, 0x6F, 0x20,
+                                0x57, 0x6F, 0x72, 0x6C, 0x64, 0x4E00,
+                                0xAC00, 0xFF45, 0x0103, 0x20, 0x33,
+                                0x20, 0x33, 0x33, 0x33, 0x20, 0x33,
+                                0x33, 0x33, 0x20, 0x48, 0x65, 0x6C,
+                                0x6C, 0x6F};
+
+  for (uint32_t i=0; i<out.Length(); i++) {
+    ASSERT_EQ(uout[i], expected[i]);
+  }
+}
+
diff --git a/xpcom/tests/gtest/TestThreadPool.cpp b/xpcom/tests/gtest/TestThreadPool.cpp
new file mode 100644
index 000000000..56abf7608
--- /dev/null
+++ b/xpcom/tests/gtest/TestThreadPool.cpp
@@ -0,0 +1,124 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "nsXPCOM.h"
+#include "nsXPCOMCIDInternal.h"
+#include "nsIThreadPool.h"
+#include "nsComponentManagerUtils.h"
+#include "nsCOMPtr.h"
+#include "nsIRunnable.h"
+#include "nsThreadUtils.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/Monitor.h"
+#include "gtest/gtest.h"
+
+using namespace mozilla;
+
+class Task final : public nsIRunnable
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  explicit Task(int i) : mIndex(i) {}
+
+  NS_IMETHOD Run() override
+  {
+    printf("###(%d) running from thread: %p\n", mIndex, (void *) PR_GetCurrentThread());
+    int r = (int) ((float) rand() * 200 / RAND_MAX);
+    PR_Sleep(PR_MillisecondsToInterval(r));
+    printf("###(%d) exiting from thread: %p\n", mIndex, (void *) PR_GetCurrentThread());
+    ++sCount;
+    return NS_OK;
+  }
+
+  static mozilla::Atomic<int> sCount;
+
+private:
+  ~Task() {}
+
+  int mIndex;
+};
+NS_IMPL_ISUPPORTS(Task, nsIRunnable)
+
+mozilla::Atomic<int> Task::sCount;
+
+TEST(ThreadPool, Main)
+{
+  nsCOMPtr<nsIThreadPool> pool = do_CreateInstance(NS_THREADPOOL_CONTRACTID);
+  EXPECT_TRUE(pool);
+
+  for (int i = 0; i < 100; ++i) {
+    nsCOMPtr<nsIRunnable> task = new Task(i);
+    EXPECT_TRUE(task);
+
+    pool->Dispatch(task, NS_DISPATCH_NORMAL);
+  }
+
+  pool->Shutdown();
+  EXPECT_EQ(Task::sCount, 100);
+}
+
+TEST(ThreadPool, Parallelism)
+{
+  nsCOMPtr<nsIThreadPool> pool = do_CreateInstance(NS_THREADPOOL_CONTRACTID);
+  EXPECT_TRUE(pool);
+
+  // Dispatch and sleep to ensure we have an idle thread
+  nsCOMPtr<nsIRunnable> r0 = new Runnable();
+  pool->Dispatch(r0, NS_DISPATCH_SYNC);
+  PR_Sleep(PR_SecondsToInterval(2));
+
+  class Runnable1 : public Runnable {
+  public:
+    Runnable1(Monitor& aMonitor, bool& aDone)
+      : mMonitor(aMonitor), mDone(aDone) {}
+
+    NS_IMETHOD Run() override {
+      MonitorAutoLock mon(mMonitor);
+      if (!mDone) {
+        // Wait for a reasonable timeout since we don't want to block gtests
+        // forever should any regression happen.
+        mon.Wait(PR_SecondsToInterval(300));
+      }
+      EXPECT_TRUE(mDone);
+      return NS_OK;
+    }
+  private:
+    Monitor& mMonitor;
+    bool& mDone;
+  };
+
+  class Runnable2 : public Runnable {
+  public:
+    Runnable2(Monitor& aMonitor, bool& aDone)
+      : mMonitor(aMonitor), mDone(aDone) {}
+
+    NS_IMETHOD Run() override {
+      MonitorAutoLock mon(mMonitor);
+      mDone = true;
+      mon.NotifyAll();
+      return NS_OK;
+    }
+  private:
+    Monitor& mMonitor;
+    bool& mDone;
+  };
+
+  // Dispatch 2 events in a row. Since we are still within the thread limit,
+  // We should wake up the idle thread and spawn a new thread so these 2 events
+  // can run in parallel. We will time out if r1 and r2 run in sequence for r1
+  // won't finish until r2 finishes.
+  Monitor mon("ThreadPool::Parallelism");
+  bool done = false;
+  nsCOMPtr<nsIRunnable> r1 = new Runnable1(mon, done);
+  nsCOMPtr<nsIRunnable> r2 = new Runnable2(mon, done);
+  pool->Dispatch(r1, NS_DISPATCH_NORMAL);
+  pool->Dispatch(r2, NS_DISPATCH_NORMAL);
+
+  pool->Shutdown();
+}
diff --git a/xpcom/tests/gtest/TestThreadPoolListener.cpp b/xpcom/tests/gtest/TestThreadPoolListener.cpp
new file mode 100644
index 000000000..f95106fa8
--- /dev/null
+++ b/xpcom/tests/gtest/TestThreadPoolListener.cpp
@@ -0,0 +1,209 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIThread.h"
+#include "nsIThreadPool.h"
+
+#include "nsComponentManagerUtils.h"
+#include "nsThreadUtils.h"
+#include "nsXPCOMCIDInternal.h"
+#include "pratom.h"
+#include "prinrval.h"
+#include "prmon.h"
+#include "prthread.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+
+#include "mozilla/ReentrantMonitor.h"
+
+#include "gtest/gtest.h"
+
+using namespace mozilla;
+
+#define NUMBER_OF_THREADS 4
+
+// One hour... because test boxes can be slow!
+#define IDLE_THREAD_TIMEOUT 3600000
+
+namespace TestThreadPoolListener
+{
+static nsIThread** gCreatedThreadList = nullptr;
+static nsIThread** gShutDownThreadList = nullptr;
+
+static ReentrantMonitor* gReentrantMonitor = nullptr;
+
+static bool gAllRunnablesPosted = false;
+static bool gAllThreadsCreated = false;
+static bool gAllThreadsShutDown = false;
+
+class Listener final : public nsIThreadPoolListener
+{
+  ~Listener() {}
+
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSITHREADPOOLLISTENER
+};
+
+NS_IMPL_ISUPPORTS(Listener, nsIThreadPoolListener)
+
+NS_IMETHODIMP
+Listener::OnThreadCreated()
+{
+  nsCOMPtr<nsIThread> current(do_GetCurrentThread());
+  EXPECT_TRUE(current) << "Couldn't get current thread!";
+
+  ReentrantMonitorAutoEnter mon(*gReentrantMonitor);
+
+  while (!gAllRunnablesPosted) {
+    mon.Wait();
+  }
+
+  for (uint32_t i = 0; i < NUMBER_OF_THREADS; i++) {
+    nsIThread* thread = gCreatedThreadList[i];
+    EXPECT_NE(thread, current) << "Saw the same thread twice!";
+
+    if (!thread) {
+      gCreatedThreadList[i] = current;
+      if (i == (NUMBER_OF_THREADS - 1)) {
+        gAllThreadsCreated = true;
+        mon.NotifyAll();
+      }
+      return NS_OK;
+    }
+  }
+
+  EXPECT_TRUE(false) << "Too many threads!";
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+Listener::OnThreadShuttingDown()
+{
+  nsCOMPtr<nsIThread> current(do_GetCurrentThread());
+  EXPECT_TRUE(current) << "Couldn't get current thread!";
+
+  ReentrantMonitorAutoEnter mon(*gReentrantMonitor);
+
+  for (uint32_t i = 0; i < NUMBER_OF_THREADS; i++) {
+    nsIThread* thread = gShutDownThreadList[i];
+    EXPECT_NE(thread, current) << "Saw the same thread twice!";
+
+    if (!thread) {
+      gShutDownThreadList[i] = current;
+      if (i == (NUMBER_OF_THREADS - 1)) {
+        gAllThreadsShutDown = true;
+        mon.NotifyAll();
+      }
+      return NS_OK;
+    }
+  }
+
+  EXPECT_TRUE(false) << "Too many threads!";
+  return NS_ERROR_FAILURE;
+}
+
+class AutoCreateAndDestroyReentrantMonitor
+{
+public:
+  explicit AutoCreateAndDestroyReentrantMonitor(ReentrantMonitor** aReentrantMonitorPtr)
+  : mReentrantMonitorPtr(aReentrantMonitorPtr) {
+    *aReentrantMonitorPtr = new ReentrantMonitor("TestThreadPoolListener::AutoMon");
+    MOZ_RELEASE_ASSERT(*aReentrantMonitorPtr, "Out of memory!");
+  }
+
+  ~AutoCreateAndDestroyReentrantMonitor() {
+    delete *mReentrantMonitorPtr;
+    *mReentrantMonitorPtr = nullptr;
+  }
+
+private:
+  ReentrantMonitor** mReentrantMonitorPtr;
+};
+
+TEST(ThreadPoolListener, Test)
+{
+  nsIThread* createdThreadList[NUMBER_OF_THREADS] = { nullptr };
+  gCreatedThreadList = createdThreadList;
+
+  nsIThread* shutDownThreadList[NUMBER_OF_THREADS] = { nullptr };
+  gShutDownThreadList = shutDownThreadList;
+
+  AutoCreateAndDestroyReentrantMonitor newMon(&gReentrantMonitor);
+  ASSERT_TRUE(gReentrantMonitor);
+
+  nsresult rv;
+
+  nsCOMPtr<nsIThreadPool> pool =
+    do_CreateInstance(NS_THREADPOOL_CONTRACTID, &rv);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  rv = pool->SetThreadLimit(NUMBER_OF_THREADS);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  rv = pool->SetIdleThreadLimit(NUMBER_OF_THREADS);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  rv = pool->SetIdleThreadTimeout(IDLE_THREAD_TIMEOUT);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsIThreadPoolListener> listener = new Listener();
+  ASSERT_TRUE(listener);
+
+  rv = pool->SetListener(listener);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  {
+    ReentrantMonitorAutoEnter mon(*gReentrantMonitor);
+
+    for (uint32_t i = 0; i < NUMBER_OF_THREADS; i++) {
+      nsCOMPtr<nsIRunnable> runnable = new Runnable();
+      ASSERT_TRUE(runnable);
+
+      rv = pool->Dispatch(runnable, NS_DISPATCH_NORMAL);
+      ASSERT_TRUE(NS_SUCCEEDED(rv));
+    }
+
+    gAllRunnablesPosted = true;
+    mon.NotifyAll();
+  }
+
+  {
+    ReentrantMonitorAutoEnter mon(*gReentrantMonitor);
+    while (!gAllThreadsCreated) {
+      mon.Wait();
+    }
+  }
+
+  rv = pool->Shutdown();
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  {
+    ReentrantMonitorAutoEnter mon(*gReentrantMonitor);
+    while (!gAllThreadsShutDown) {
+      mon.Wait();
+    }
+  }
+
+  for (uint32_t i = 0; i < NUMBER_OF_THREADS; i++) {
+    nsIThread* created = gCreatedThreadList[i];
+    ASSERT_TRUE(created);
+
+    bool match = false;
+    for (uint32_t j = 0; j < NUMBER_OF_THREADS; j++) {
+      nsIThread* destroyed = gShutDownThreadList[j];
+      ASSERT_TRUE(destroyed);
+
+      if (destroyed == created) {
+        match = true;
+        break;
+      }
+    }
+
+    ASSERT_TRUE(match);
+  }
+}
+
+} // namespace TestThreadPoolListener
diff --git a/xpcom/tests/gtest/TestThreadUtils.cpp b/xpcom/tests/gtest/TestThreadUtils.cpp
new file mode 100644
index 000000000..0d5d2f234
--- /dev/null
+++ b/xpcom/tests/gtest/TestThreadUtils.cpp
@@ -0,0 +1,378 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+* License, v. 2.0. If a copy of the MPL was not distributed with this
+* file, You can obtain one at http:mozilla.org/MPL/2.0/. */
+
+#include "nsThreadUtils.h"
+
+#include "gtest/gtest.h"
+
+using namespace mozilla;
+
+enum {
+  TEST_CALL_VOID_ARG_VOID_RETURN,
+  TEST_CALL_VOID_ARG_VOID_RETURN_CONST,
+  TEST_CALL_VOID_ARG_NONVOID_RETURN,
+  TEST_CALL_NONVOID_ARG_VOID_RETURN,
+  TEST_CALL_NONVOID_ARG_NONVOID_RETURN,
+  TEST_CALL_NONVOID_ARG_VOID_RETURN_EXPLICIT,
+  TEST_CALL_NONVOID_ARG_NONVOID_RETURN_EXPLICIT,
+#ifdef HAVE_STDCALL
+  TEST_STDCALL_VOID_ARG_VOID_RETURN,
+  TEST_STDCALL_VOID_ARG_NONVOID_RETURN,
+  TEST_STDCALL_NONVOID_ARG_VOID_RETURN,
+  TEST_STDCALL_NONVOID_ARG_NONVOID_RETURN,
+  TEST_STDCALL_NONVOID_ARG_NONVOID_RETURN_EXPLICIT,
+#endif
+  TEST_CALL_NEWTHREAD_SUICIDAL,
+  MAX_TESTS
+};
+
+bool gRunnableExecuted[MAX_TESTS];
+
+class nsFoo : public nsISupports {
+  NS_DECL_ISUPPORTS
+  nsresult DoFoo(bool* aBool) {
+    *aBool = true;
+    return NS_OK;
+  }
+
+private:
+  virtual ~nsFoo() {}
+};
+
+NS_IMPL_ISUPPORTS0(nsFoo)
+
+class TestSuicide : public mozilla::Runnable {
+  NS_IMETHOD Run() override {
+    // Runs first time on thread "Suicide", then dies on MainThread
+    if (!NS_IsMainThread()) {
+      mThread = do_GetCurrentThread();
+      NS_DispatchToMainThread(this);
+      return NS_OK;
+    }
+    MOZ_RELEASE_ASSERT(mThread);
+    mThread->Shutdown();
+    gRunnableExecuted[TEST_CALL_NEWTHREAD_SUICIDAL] = true;
+    return NS_OK;
+  }
+
+private:
+  nsCOMPtr<nsIThread> mThread;
+};
+
+class nsBar : public nsISupports {
+  virtual ~nsBar() {}
+public:
+  NS_DECL_ISUPPORTS
+  void DoBar1(void) {
+    gRunnableExecuted[TEST_CALL_VOID_ARG_VOID_RETURN] = true;
+  }
+  void DoBar1Const(void) const {
+    gRunnableExecuted[TEST_CALL_VOID_ARG_VOID_RETURN_CONST] = true;
+  }
+  nsresult DoBar2(void) {
+    gRunnableExecuted[TEST_CALL_VOID_ARG_NONVOID_RETURN] = true;
+    return NS_OK;
+  }
+  void DoBar3(nsFoo* aFoo) {
+    aFoo->DoFoo(&gRunnableExecuted[TEST_CALL_NONVOID_ARG_VOID_RETURN]);
+  }
+  nsresult DoBar4(nsFoo* aFoo) {
+    return aFoo->DoFoo(&gRunnableExecuted[TEST_CALL_NONVOID_ARG_NONVOID_RETURN]);
+  }
+  void DoBar5(nsFoo* aFoo) {
+    if (aFoo)
+      gRunnableExecuted[TEST_CALL_NONVOID_ARG_VOID_RETURN_EXPLICIT] = true;
+  }
+  nsresult DoBar6(char* aFoo) {
+    if (strlen(aFoo))
+      gRunnableExecuted[TEST_CALL_NONVOID_ARG_NONVOID_RETURN_EXPLICIT] = true;
+    return NS_OK;
+  }
+#ifdef HAVE_STDCALL
+  void __stdcall DoBar1std(void) {
+    gRunnableExecuted[TEST_STDCALL_VOID_ARG_VOID_RETURN] = true;
+  }
+  nsresult __stdcall DoBar2std(void) {
+    gRunnableExecuted[TEST_STDCALL_VOID_ARG_NONVOID_RETURN] = true;
+    return NS_OK;
+  }
+  void __stdcall DoBar3std(nsFoo* aFoo) {
+    aFoo->DoFoo(&gRunnableExecuted[TEST_STDCALL_NONVOID_ARG_VOID_RETURN]);
+  }
+  nsresult __stdcall DoBar4std(nsFoo* aFoo) {
+    return aFoo->DoFoo(&gRunnableExecuted[TEST_STDCALL_NONVOID_ARG_NONVOID_RETURN]);
+  }
+  void __stdcall DoBar5std(nsFoo* aFoo) {
+    if (aFoo)
+      gRunnableExecuted[TEST_STDCALL_NONVOID_ARG_VOID_RETURN_EXPLICIT] = true;
+  }
+  nsresult __stdcall DoBar6std(char* aFoo) {
+    if (strlen(aFoo))
+      gRunnableExecuted[TEST_CALL_NONVOID_ARG_VOID_RETURN_EXPLICIT] = true;
+    return NS_OK;
+  }
+#endif
+};
+
+NS_IMPL_ISUPPORTS0(nsBar)
+
+struct TestCopyWithNoMove
+{
+  explicit TestCopyWithNoMove(int* aCopyCounter) : mCopyCounter(aCopyCounter) {}
+  TestCopyWithNoMove(const TestCopyWithNoMove& a) : mCopyCounter(a.mCopyCounter) { ++mCopyCounter; };
+  // No 'move' declaration, allows passing object by rvalue copy.
+  // Destructor nulls member variable...
+  ~TestCopyWithNoMove() { mCopyCounter = nullptr; }
+  // ... so we can check that the object is called when still alive.
+  void operator()() { MOZ_RELEASE_ASSERT(mCopyCounter); }
+  int* mCopyCounter;
+};
+struct TestCopyWithDeletedMove
+{
+  explicit TestCopyWithDeletedMove(int* aCopyCounter) : mCopyCounter(aCopyCounter) {}
+  TestCopyWithDeletedMove(const TestCopyWithDeletedMove& a) : mCopyCounter(a.mCopyCounter) { ++mCopyCounter; };
+  // Deleted move prevents passing by rvalue (even if copy would work)
+  TestCopyWithDeletedMove(TestCopyWithDeletedMove&&) = delete;
+  ~TestCopyWithDeletedMove() { mCopyCounter = nullptr; }
+  void operator()() { MOZ_RELEASE_ASSERT(mCopyCounter); }
+  int* mCopyCounter;
+};
+struct TestMove
+{
+  explicit TestMove(int* aMoveCounter) : mMoveCounter(aMoveCounter) {}
+  TestMove(const TestMove&) = delete;
+  TestMove(TestMove&& a) : mMoveCounter(a.mMoveCounter) { a.mMoveCounter = nullptr; ++mMoveCounter; }
+  ~TestMove() { mMoveCounter = nullptr; }
+  void operator()() { MOZ_RELEASE_ASSERT(mMoveCounter); }
+  int* mMoveCounter;
+};
+struct TestCopyMove
+{
+  TestCopyMove(int* aCopyCounter, int* aMoveCounter) : mCopyCounter(aCopyCounter), mMoveCounter(aMoveCounter) {}
+  TestCopyMove(const TestCopyMove& a) : mCopyCounter(a.mCopyCounter), mMoveCounter(a.mMoveCounter) { ++mCopyCounter; };
+  TestCopyMove(TestCopyMove&& a) : mCopyCounter(a.mCopyCounter), mMoveCounter(a.mMoveCounter) { a.mMoveCounter = nullptr; ++mMoveCounter; }
+  ~TestCopyMove() { mCopyCounter = nullptr; mMoveCounter = nullptr; }
+  void operator()() { MOZ_RELEASE_ASSERT(mCopyCounter); MOZ_RELEASE_ASSERT(mMoveCounter); }
+  int* mCopyCounter;
+  int* mMoveCounter;
+};
+
+static void Expect(const char* aContext, int aCounter, int aMaxExpected)
+{
+  EXPECT_LE(aCounter, aMaxExpected) << aContext;
+}
+
+TEST(ThreadUtils, NewRunnableFunction)
+{
+  // Test NS_NewRunnableFunction with copyable-only function object.
+  {
+    int copyCounter = 0;
+    {
+      nsCOMPtr<nsIRunnable> trackedRunnable;
+      {
+        TestCopyWithNoMove tracker(&copyCounter);
+        trackedRunnable = NS_NewRunnableFunction(tracker);
+        // Original 'tracker' is destroyed here.
+      }
+      // Verify that the runnable contains a non-destroyed function object.
+      trackedRunnable->Run();
+    }
+    Expect("NS_NewRunnableFunction with copyable-only (and no move) function, copies",
+           copyCounter, 1);
+  }
+  {
+    int copyCounter = 0;
+    {
+      nsCOMPtr<nsIRunnable> trackedRunnable;
+      {
+        // Passing as rvalue, but using copy.
+        // (TestCopyWithDeletedMove wouldn't allow this.)
+        trackedRunnable = NS_NewRunnableFunction(TestCopyWithNoMove(&copyCounter));
+      }
+      trackedRunnable->Run();
+    }
+    Expect("NS_NewRunnableFunction with copyable-only (and no move) function rvalue, copies",
+           copyCounter, 1);
+  }
+  {
+    int copyCounter = 0;
+    {
+      nsCOMPtr<nsIRunnable> trackedRunnable;
+      {
+        TestCopyWithDeletedMove tracker(&copyCounter);
+        trackedRunnable = NS_NewRunnableFunction(tracker);
+      }
+      trackedRunnable->Run();
+    }
+    Expect("NS_NewRunnableFunction with copyable-only (and deleted move) function, copies",
+           copyCounter, 1);
+  }
+
+  // Test NS_NewRunnableFunction with movable-only function object.
+  {
+    int moveCounter = 0;
+    {
+      nsCOMPtr<nsIRunnable> trackedRunnable;
+      {
+        TestMove tracker(&moveCounter);
+        trackedRunnable = NS_NewRunnableFunction(Move(tracker));
+      }
+      trackedRunnable->Run();
+    }
+    Expect("NS_NewRunnableFunction with movable-only function, moves",
+           moveCounter, 1);
+  }
+  {
+    int moveCounter = 0;
+    {
+      nsCOMPtr<nsIRunnable> trackedRunnable;
+      {
+        trackedRunnable = NS_NewRunnableFunction(TestMove(&moveCounter));
+      }
+      trackedRunnable->Run();
+    }
+    Expect("NS_NewRunnableFunction with movable-only function rvalue, moves",
+           moveCounter, 1);
+  }
+
+  // Test NS_NewRunnableFunction with copyable&movable function object.
+  {
+    int copyCounter = 0;
+    int moveCounter = 0;
+    {
+      nsCOMPtr<nsIRunnable> trackedRunnable;
+      {
+        TestCopyMove tracker(&copyCounter, &moveCounter);
+        trackedRunnable = NS_NewRunnableFunction(Move(tracker));
+      }
+      trackedRunnable->Run();
+    }
+    Expect("NS_NewRunnableFunction with copyable&movable function, copies",
+           copyCounter, 0);
+    Expect("NS_NewRunnableFunction with copyable&movable function, moves",
+           moveCounter, 1);
+  }
+  {
+    int copyCounter = 0;
+    int moveCounter = 0;
+    {
+      nsCOMPtr<nsIRunnable> trackedRunnable;
+      {
+        trackedRunnable =
+          NS_NewRunnableFunction(TestCopyMove(&copyCounter, &moveCounter));
+      }
+      trackedRunnable->Run();
+    }
+    Expect("NS_NewRunnableFunction with copyable&movable function rvalue, copies",
+           copyCounter, 0);
+    Expect("NS_NewRunnableFunction with copyable&movable function rvalue, moves",
+           moveCounter, 1);
+  }
+
+  // Test NS_NewRunnableFunction with copyable-only lambda capture.
+  {
+    int copyCounter = 0;
+    {
+      nsCOMPtr<nsIRunnable> trackedRunnable;
+      {
+        TestCopyWithNoMove tracker(&copyCounter);
+        // Expect 2 copies (here -> local lambda -> runnable lambda).
+        trackedRunnable = NS_NewRunnableFunction([tracker]() mutable { tracker(); });
+      }
+      trackedRunnable->Run();
+    }
+    Expect("NS_NewRunnableFunction with copyable-only (and no move) capture, copies",
+           copyCounter, 2);
+  }
+  {
+    int copyCounter = 0;
+    {
+      nsCOMPtr<nsIRunnable> trackedRunnable;
+      {
+        TestCopyWithDeletedMove tracker(&copyCounter);
+        // Expect 2 copies (here -> local lambda -> runnable lambda).
+        trackedRunnable = NS_NewRunnableFunction([tracker]() mutable { tracker(); });
+      }
+      trackedRunnable->Run();
+    }
+    Expect("NS_NewRunnableFunction with copyable-only (and deleted move) capture, copies",
+           copyCounter, 2);
+  }
+
+  // Note: Not possible to use move-only captures.
+  // (Until we can use C++14 generalized lambda captures)
+
+  // Test NS_NewRunnableFunction with copyable&movable lambda capture.
+  {
+    int copyCounter = 0;
+    int moveCounter = 0;
+    {
+      nsCOMPtr<nsIRunnable> trackedRunnable;
+      {
+        TestCopyMove tracker(&copyCounter, &moveCounter);
+        trackedRunnable = NS_NewRunnableFunction([tracker]() mutable { tracker(); });
+        // Expect 1 copy (here -> local lambda) and 1 move (local -> runnable lambda).
+      }
+      trackedRunnable->Run();
+    }
+    Expect("NS_NewRunnableFunction with copyable&movable capture, copies",
+           copyCounter, 1);
+    Expect("NS_NewRunnableFunction with copyable&movable capture, moves",
+           moveCounter, 1);
+  }
+}
+
+TEST(ThreadUtils, RunnableMethod)
+{
+  memset(gRunnableExecuted, false, MAX_TESTS * sizeof(bool));
+  // Scope the smart ptrs so that the runnables need to hold on to whatever they need
+  {
+    RefPtr<nsFoo> foo = new nsFoo();
+    RefPtr<nsBar> bar = new nsBar();
+    RefPtr<const nsBar> constBar = bar;
+
+    // This pointer will be freed at the end of the block
+    // Do not dereference this pointer in the runnable method!
+    RefPtr<nsFoo> rawFoo = new nsFoo();
+
+    // Read only string. Dereferencing in runnable method to check this works.
+    char* message = (char*)"Test message";
+
+    NS_DispatchToMainThread(NewRunnableMethod(bar, &nsBar::DoBar1));
+    NS_DispatchToMainThread(NewRunnableMethod(constBar, &nsBar::DoBar1Const));
+    NS_DispatchToMainThread(NewRunnableMethod(bar, &nsBar::DoBar2));
+    NS_DispatchToMainThread(NewRunnableMethod<RefPtr<nsFoo>>
+      (bar, &nsBar::DoBar3, foo));
+    NS_DispatchToMainThread(NewRunnableMethod<RefPtr<nsFoo>>
+      (bar, &nsBar::DoBar4, foo));
+    NS_DispatchToMainThread(NewRunnableMethod<nsFoo*>(bar, &nsBar::DoBar5, rawFoo));
+    NS_DispatchToMainThread(NewRunnableMethod<char*>(bar, &nsBar::DoBar6, message));
+#ifdef HAVE_STDCALL
+    NS_DispatchToMainThread(NewRunnableMethod(bar, &nsBar::DoBar1std));
+    NS_DispatchToMainThread(NewRunnableMethod(bar, &nsBar::DoBar2std));
+    NS_DispatchToMainThread(NewRunnableMethod<RefPtr<nsFoo>>
+      (bar, &nsBar::DoBar3std, foo));
+    NS_DispatchToMainThread(NewRunnableMethod<RefPtr<nsFoo>>
+      (bar, &nsBar::DoBar4std, foo));
+    NS_DispatchToMainThread(NewRunnableMethod<nsFoo*>(bar, &nsBar::DoBar5std, rawFoo));
+    NS_DispatchToMainThread(NewRunnableMethod<char*>(bar, &nsBar::DoBar6std, message));
+#endif
+  }
+
+  // Spin the event loop
+  NS_ProcessPendingEvents(nullptr);
+
+  // Now test a suicidal event in NS_New(Named)Thread
+  nsCOMPtr<nsIThread> thread;
+  NS_NewNamedThread("SuicideThread", getter_AddRefs(thread), new TestSuicide());
+  ASSERT_TRUE(thread);
+
+  while (!gRunnableExecuted[TEST_CALL_NEWTHREAD_SUICIDAL]) {
+    NS_ProcessPendingEvents(nullptr);
+  }
+
+  for (uint32_t i = 0; i < MAX_TESTS; i++) {
+    EXPECT_TRUE(gRunnableExecuted[i]) << "Error in test " << i;
+  }
+}
diff --git a/xpcom/tests/gtest/TestThreads.cpp b/xpcom/tests/gtest/TestThreads.cpp
new file mode 100644
index 000000000..4f6055dce
--- /dev/null
+++ b/xpcom/tests/gtest/TestThreads.cpp
@@ -0,0 +1,275 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsThreadUtils.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include "nspr.h"
+#include "nsCOMPtr.h"
+#include "nsIServiceManager.h"
+#include "nsXPCOM.h"
+#include "mozilla/Monitor.h"
+#include "gtest/gtest.h"
+
+class nsRunner final : public nsIRunnable {
+  ~nsRunner() {}
+public:
+    NS_DECL_THREADSAFE_ISUPPORTS
+
+    NS_IMETHOD Run() override {
+        nsCOMPtr<nsIThread> thread;
+        nsresult rv = NS_GetCurrentThread(getter_AddRefs(thread));
+        EXPECT_TRUE(NS_SUCCEEDED(rv));
+        printf("running %d on thread %p\n", mNum, (void *)thread.get());
+
+        // if we don't do something slow, we'll never see the other
+        // worker threads run
+        PR_Sleep(PR_MillisecondsToInterval(100));
+
+        return rv;
+    }
+
+    explicit nsRunner(int num) : mNum(num) {
+    }
+
+protected:
+    int mNum;
+};
+
+NS_IMPL_ISUPPORTS(nsRunner, nsIRunnable)
+
+TEST(Threads, Main)
+{
+    nsresult rv;
+
+    nsCOMPtr<nsIRunnable> event = new nsRunner(0);
+    EXPECT_TRUE(event);
+
+    nsCOMPtr<nsIThread> runner;
+    rv = NS_NewThread(getter_AddRefs(runner), event);
+    EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+    nsCOMPtr<nsIThread> thread;
+    rv = NS_GetCurrentThread(getter_AddRefs(thread));
+    EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+    rv = runner->Shutdown();     // wait for the runner to die before quitting
+    EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+    PR_Sleep(PR_MillisecondsToInterval(100));       // hopefully the runner will quit here
+}
+
+class nsStressRunner final : public nsIRunnable {
+public:
+    NS_DECL_THREADSAFE_ISUPPORTS
+
+    NS_IMETHOD Run() override {
+        EXPECT_FALSE(mWasRun);
+        mWasRun = true;
+        PR_Sleep(1);
+        if (!PR_AtomicDecrement(&gNum)) {
+            printf("   last thread was %d\n", mNum);
+        }
+        return NS_OK;
+    }
+
+    explicit nsStressRunner(int num) : mNum(num), mWasRun(false) {
+        PR_AtomicIncrement(&gNum);
+    }
+
+    static int32_t GetGlobalCount() {return gNum;}
+
+private:
+    ~nsStressRunner() {
+        EXPECT_TRUE(mWasRun);
+    }
+
+protected:
+    static int32_t gNum;
+    int32_t mNum;
+    bool mWasRun;
+};
+
+int32_t nsStressRunner::gNum = 0;
+
+NS_IMPL_ISUPPORTS(nsStressRunner, nsIRunnable)
+
+TEST(Threads, Stress)
+{
+    const int loops = 1000;
+    const int threads = 50;
+
+    for (int i = 0; i < loops; i++) {
+        printf("Loop %d of %d\n", i+1, loops);
+
+        int k;
+        nsIThread** array = new nsIThread*[threads];
+
+        EXPECT_EQ(nsStressRunner::GetGlobalCount(), 0);
+
+        for (k = 0; k < threads; k++) {
+            nsCOMPtr<nsIThread> t;
+            nsresult rv = NS_NewThread(getter_AddRefs(t), new nsStressRunner(k));
+            EXPECT_TRUE(NS_SUCCEEDED(rv));
+            NS_ADDREF(array[k] = t);
+        }
+
+        for (k = threads-1; k >= 0; k--) {
+            array[k]->Shutdown();
+            NS_RELEASE(array[k]);    
+        }
+        delete [] array;
+    }
+}
+
+mozilla::Monitor* gAsyncShutdownReadyMonitor;
+mozilla::Monitor* gBeginAsyncShutdownMonitor;
+
+class AsyncShutdownPreparer : public nsIRunnable {
+public:
+    NS_DECL_THREADSAFE_ISUPPORTS
+
+    NS_IMETHOD Run() override {
+        EXPECT_FALSE(mWasRun);
+        mWasRun = true;
+
+        mozilla::MonitorAutoLock lock(*gAsyncShutdownReadyMonitor);
+        lock.Notify();
+
+        return NS_OK;
+    }
+
+    explicit AsyncShutdownPreparer() : mWasRun(false) {}
+
+private:
+    virtual ~AsyncShutdownPreparer() {
+        EXPECT_TRUE(mWasRun);
+    }
+
+protected:
+    bool mWasRun;
+};
+
+NS_IMPL_ISUPPORTS(AsyncShutdownPreparer, nsIRunnable)
+
+class AsyncShutdownWaiter : public nsIRunnable {
+public:
+    NS_DECL_THREADSAFE_ISUPPORTS
+
+    NS_IMETHOD Run() override {
+        EXPECT_FALSE(mWasRun);
+        mWasRun = true;
+
+        nsCOMPtr<nsIThread> t;
+        nsresult rv;
+
+        {
+          mozilla::MonitorAutoLock lock(*gBeginAsyncShutdownMonitor);
+
+          rv = NS_NewThread(getter_AddRefs(t), new AsyncShutdownPreparer());
+          EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+          lock.Wait();
+        }
+
+        rv = t->AsyncShutdown();
+        EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+        return NS_OK;
+    }
+
+    explicit AsyncShutdownWaiter() : mWasRun(false) {}
+
+private:
+    virtual ~AsyncShutdownWaiter() {
+        EXPECT_TRUE(mWasRun);
+    }
+
+protected:
+    bool mWasRun;
+};
+
+NS_IMPL_ISUPPORTS(AsyncShutdownWaiter, nsIRunnable)
+
+class SameThreadSentinel : public nsIRunnable {
+public:
+    NS_DECL_ISUPPORTS
+
+    NS_IMETHOD Run() override {
+        mozilla::MonitorAutoLock lock(*gBeginAsyncShutdownMonitor);
+        lock.Notify();
+        return NS_OK;
+    }
+
+private:
+    virtual ~SameThreadSentinel() {}
+};
+
+NS_IMPL_ISUPPORTS(SameThreadSentinel, nsIRunnable)
+
+TEST(Threads, AsyncShutdown)
+{
+  gAsyncShutdownReadyMonitor = new mozilla::Monitor("gAsyncShutdownReady");
+  gBeginAsyncShutdownMonitor = new mozilla::Monitor("gBeginAsyncShutdown");
+
+  nsCOMPtr<nsIThread> t;
+  nsresult rv;
+
+  {
+    mozilla::MonitorAutoLock lock(*gAsyncShutdownReadyMonitor);
+
+    rv = NS_NewThread(getter_AddRefs(t), new AsyncShutdownWaiter());
+    EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+    lock.Wait();
+  }
+
+  NS_DispatchToCurrentThread(new SameThreadSentinel());
+  rv = t->Shutdown();
+  EXPECT_TRUE(NS_SUCCEEDED(rv));
+
+  delete gAsyncShutdownReadyMonitor;
+  delete gBeginAsyncShutdownMonitor;
+}
+
+static void threadProc(void *arg)
+{
+    // printf("   running thread %d\n", (int) arg);
+    PR_Sleep(1);
+    EXPECT_EQ(PR_JOINABLE_THREAD, PR_GetThreadState(PR_GetCurrentThread()));
+}
+
+TEST(Threads, StressNSPR)
+{
+    const int loops = 1000;
+    const int threads = 50;
+
+    for (int i = 0; i < loops; i++) {
+        printf("Loop %d of %d\n", i+1, loops);
+
+        intptr_t k;
+        PRThread** array = new PRThread*[threads];
+
+        for (k = 0; k < threads; k++) {
+            array[k] = PR_CreateThread(PR_USER_THREAD,
+                                       threadProc, (void*) k,
+                                       PR_PRIORITY_NORMAL,
+                                       PR_GLOBAL_THREAD,
+                                       PR_JOINABLE_THREAD,
+                                       0);
+            EXPECT_TRUE(array[k]);
+        }
+
+        for (k = 0; k < threads; k++) {
+            EXPECT_EQ(PR_JOINABLE_THREAD, PR_GetThreadState(array[k]));
+        }
+
+        for (k = threads-1; k >= 0; k--) {
+            PR_JoinThread(array[k]);
+        }
+        delete [] array;
+    }
+}
diff --git a/xpcom/tests/gtest/TestTimeStamp.cpp b/xpcom/tests/gtest/TestTimeStamp.cpp
new file mode 100644
index 000000000..4e85b7e24
--- /dev/null
+++ b/xpcom/tests/gtest/TestTimeStamp.cpp
@@ -0,0 +1,70 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/TimeStamp.h"
+
+#include "prinrval.h"
+#include "prthread.h"
+
+#include "gtest/gtest.h"
+
+using mozilla::TimeStamp;
+using mozilla::TimeDuration;
+
+TEST(TimeStamp, Main)
+{
+  TimeDuration td;
+  EXPECT_TRUE(td.ToSeconds() == 0.0);
+  EXPECT_TRUE(TimeDuration::FromSeconds(5).ToSeconds() == 5.0);
+  EXPECT_TRUE(TimeDuration::FromMilliseconds(5000).ToSeconds() == 5.0);
+  EXPECT_TRUE(TimeDuration::FromSeconds(1) < TimeDuration::FromSeconds(2));
+  EXPECT_FALSE(TimeDuration::FromSeconds(1) < TimeDuration::FromSeconds(1));
+  EXPECT_TRUE(TimeDuration::FromSeconds(2) > TimeDuration::FromSeconds(1));
+  EXPECT_FALSE(TimeDuration::FromSeconds(1) > TimeDuration::FromSeconds(1));
+  EXPECT_TRUE(TimeDuration::FromSeconds(1) <= TimeDuration::FromSeconds(2));
+  EXPECT_TRUE(TimeDuration::FromSeconds(1) <= TimeDuration::FromSeconds(1));
+  EXPECT_FALSE(TimeDuration::FromSeconds(2) <= TimeDuration::FromSeconds(1));
+  EXPECT_TRUE(TimeDuration::FromSeconds(2) >= TimeDuration::FromSeconds(1));
+  EXPECT_TRUE(TimeDuration::FromSeconds(1) >= TimeDuration::FromSeconds(1));
+  EXPECT_FALSE(TimeDuration::FromSeconds(1) >= TimeDuration::FromSeconds(2));
+
+  TimeStamp ts;
+  EXPECT_TRUE(ts.IsNull());
+
+  ts = TimeStamp::Now();
+  EXPECT_TRUE(!ts.IsNull());
+  EXPECT_TRUE((ts - ts).ToSeconds() == 0.0);
+
+  PR_Sleep(PR_SecondsToInterval(2));
+
+  TimeStamp ts2(TimeStamp::Now());
+  EXPECT_TRUE(ts2 > ts);
+  EXPECT_FALSE(ts > ts);
+  EXPECT_TRUE(ts < ts2);
+  EXPECT_FALSE(ts < ts);
+  EXPECT_TRUE(ts <= ts2);
+  EXPECT_TRUE(ts <= ts);
+  EXPECT_FALSE(ts2 <= ts);
+  EXPECT_TRUE(ts2 >= ts);
+  EXPECT_TRUE(ts2 >= ts);
+  EXPECT_FALSE(ts >= ts2);
+
+  // We can't be sure exactly how long PR_Sleep slept for. It should have
+  // slept for at least one second. We might have slept a lot longer due
+  // to process scheduling, but hopefully not more than 10 seconds.
+  td = ts2 - ts;
+  EXPECT_TRUE(td.ToSeconds() > 1.0);
+  EXPECT_TRUE(td.ToSeconds() < 20.0);
+  td = ts - ts2;
+  EXPECT_TRUE(td.ToSeconds() < -1.0);
+  EXPECT_TRUE(td.ToSeconds() > -20.0);
+
+  double resolution = TimeDuration::Resolution().ToSecondsSigDigits();
+  printf(" (platform timer resolution is ~%g s)\n", resolution);
+  EXPECT_TRUE(1e-10 < resolution);
+  // Don't upper-bound sanity check ... although NSPR reports 1ms
+  // resolution, it might be lying, so we shouldn't compare with it
+}
diff --git a/xpcom/tests/gtest/TestTimers.cpp b/xpcom/tests/gtest/TestTimers.cpp
new file mode 100644
index 000000000..fe7520ab1
--- /dev/null
+++ b/xpcom/tests/gtest/TestTimers.cpp
@@ -0,0 +1,437 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIThread.h"
+#include "nsITimer.h"
+
+#include "nsCOMPtr.h"
+#include "nsComponentManagerUtils.h"
+#include "nsServiceManagerUtils.h"
+#include "nsThreadUtils.h"
+#include "prinrval.h"
+#include "prmon.h"
+#include "prthread.h"
+#include "mozilla/Attributes.h"
+
+#include "mozilla/ReentrantMonitor.h"
+
+#include <list>
+#include <vector>
+
+#include "gtest/gtest.h"
+
+using namespace mozilla;
+
+typedef nsresult(*TestFuncPtr)();
+
+class AutoTestThread
+{
+public:
+  AutoTestThread() {
+    nsCOMPtr<nsIThread> newThread;
+    nsresult rv = NS_NewThread(getter_AddRefs(newThread));
+    if (NS_FAILED(rv))
+      return;
+
+    newThread.swap(mThread);
+  }
+
+  ~AutoTestThread() {
+    mThread->Shutdown();
+  }
+
+  operator nsIThread*() const {
+    return mThread;
+  }
+
+  nsIThread* operator->() const MOZ_NO_ADDREF_RELEASE_ON_RETURN {
+    return mThread;
+  }
+
+private:
+  nsCOMPtr<nsIThread> mThread;
+};
+
+class AutoCreateAndDestroyReentrantMonitor
+{
+public:
+  AutoCreateAndDestroyReentrantMonitor() {
+    mReentrantMonitor = new ReentrantMonitor("TestTimers::AutoMon");
+    MOZ_RELEASE_ASSERT(mReentrantMonitor, "Out of memory!");
+  }
+
+  ~AutoCreateAndDestroyReentrantMonitor() {
+    delete mReentrantMonitor;
+  }
+
+  operator ReentrantMonitor* () {
+    return mReentrantMonitor;
+  }
+
+private:
+  ReentrantMonitor* mReentrantMonitor;
+};
+
+class TimerCallback final : public nsITimerCallback
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  TimerCallback(nsIThread** aThreadPtr, ReentrantMonitor* aReentrantMonitor)
+  : mThreadPtr(aThreadPtr), mReentrantMonitor(aReentrantMonitor) { }
+
+  NS_IMETHOD Notify(nsITimer* aTimer) override {
+    MOZ_RELEASE_ASSERT(mThreadPtr, "Callback was not supposed to be called!");
+    nsCOMPtr<nsIThread> current(do_GetCurrentThread());
+
+    ReentrantMonitorAutoEnter mon(*mReentrantMonitor);
+
+    MOZ_RELEASE_ASSERT(!*mThreadPtr, "Timer called back more than once!");
+    *mThreadPtr = current;
+
+    mon.Notify();
+
+    return NS_OK;
+  }
+private:
+  ~TimerCallback() {}
+
+  nsIThread** mThreadPtr;
+  ReentrantMonitor* mReentrantMonitor;
+};
+
+NS_IMPL_ISUPPORTS(TimerCallback, nsITimerCallback)
+
+TEST(Timers, TargetedTimers)
+{
+  AutoCreateAndDestroyReentrantMonitor newMon;
+  ASSERT_TRUE(newMon);
+
+  AutoTestThread testThread;
+  ASSERT_TRUE(testThread);
+
+  nsresult rv;
+  nsCOMPtr<nsITimer> timer = do_CreateInstance(NS_TIMER_CONTRACTID, &rv);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsIEventTarget* target = static_cast<nsIEventTarget*>(testThread);
+
+  rv = timer->SetTarget(target);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsIThread* notifiedThread = nullptr;
+
+  nsCOMPtr<nsITimerCallback> callback =
+    new TimerCallback(&notifiedThread, newMon);
+  ASSERT_TRUE(callback);
+
+  rv = timer->InitWithCallback(callback, 2000, nsITimer::TYPE_ONE_SHOT);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  ReentrantMonitorAutoEnter mon(*newMon);
+  while (!notifiedThread) {
+    mon.Wait();
+  }
+  ASSERT_EQ(notifiedThread, testThread);
+}
+
+TEST(Timers, TimerWithStoppedTarget)
+{
+  AutoTestThread testThread;
+  ASSERT_TRUE(testThread);
+
+  nsresult rv;
+  nsCOMPtr<nsITimer> timer = do_CreateInstance(NS_TIMER_CONTRACTID, &rv);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsIEventTarget* target = static_cast<nsIEventTarget*>(testThread);
+
+  rv = timer->SetTarget(target);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  // If this is called, we'll assert
+  nsCOMPtr<nsITimerCallback> callback =
+    new TimerCallback(nullptr, nullptr);
+  ASSERT_TRUE(callback);
+
+  rv = timer->InitWithCallback(callback, 100, nsITimer::TYPE_ONE_SHOT);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  testThread->Shutdown();
+
+  PR_Sleep(400);
+}
+
+#define FUZZ_MAX_TIMEOUT 9
+class FuzzTestThreadState final : public nsITimerCallback {
+  public:
+    NS_DECL_THREADSAFE_ISUPPORTS
+
+    explicit FuzzTestThreadState(nsIThread* thread) :
+      mThread(thread),
+      mStopped(false)
+    {}
+
+    class StartRunnable final : public mozilla::Runnable {
+      public:
+        explicit StartRunnable(FuzzTestThreadState* threadState) :
+          mThreadState(threadState)
+        {}
+
+        NS_IMETHOD Run() override
+        {
+          mThreadState->ScheduleOrCancelTimers();
+          return NS_OK;
+        }
+
+      private:
+        RefPtr<FuzzTestThreadState> mThreadState;
+    };
+
+    void Start()
+    {
+      nsCOMPtr<nsIRunnable> runnable = new StartRunnable(this);
+      nsresult rv = mThread->Dispatch(runnable, NS_DISPATCH_NORMAL);
+      MOZ_RELEASE_ASSERT(NS_SUCCEEDED(rv), "Failed to dispatch StartRunnable.");
+    }
+
+    void Stop()
+    {
+      mStopped = true;
+    }
+
+    NS_IMETHOD Notify(nsITimer* aTimer) override
+    {
+      bool onCorrectThread;
+      nsresult rv = mThread->IsOnCurrentThread(&onCorrectThread);
+      MOZ_RELEASE_ASSERT(NS_SUCCEEDED(rv), "Failed to perform thread check.");
+      MOZ_RELEASE_ASSERT(onCorrectThread, "Notify invoked on wrong thread.");
+
+      uint32_t delay;
+      rv = aTimer->GetDelay(&delay);
+      MOZ_RELEASE_ASSERT(NS_SUCCEEDED(rv), "GetDelay failed.");
+
+      MOZ_RELEASE_ASSERT(delay <= FUZZ_MAX_TIMEOUT,
+                         "Delay was an invalid value for this test.");
+
+      uint32_t type;
+      rv = aTimer->GetType(&type);
+      MOZ_RELEASE_ASSERT(NS_SUCCEEDED(rv), "Failed to get timer type.");
+      MOZ_RELEASE_ASSERT(type <= nsITimer::TYPE_REPEATING_PRECISE_CAN_SKIP);
+
+      if (type == nsITimer::TYPE_ONE_SHOT) {
+        MOZ_RELEASE_ASSERT(!mOneShotTimersByDelay[delay].empty(),
+                           "Unexpected one-shot timer.");
+
+        MOZ_RELEASE_ASSERT(mOneShotTimersByDelay[delay].front().get() == aTimer,
+                           "One-shot timers have been reordered.");
+
+        mOneShotTimersByDelay[delay].pop_front();
+        --mTimersOutstanding;
+      } else if (mStopped) {
+        CancelRepeatingTimer(aTimer);
+      }
+
+      ScheduleOrCancelTimers();
+      RescheduleSomeTimers();
+      return NS_OK;
+    }
+
+    bool HasTimersOutstanding() const
+    {
+      return !!mTimersOutstanding;
+    }
+
+  private:
+    ~FuzzTestThreadState()
+    {
+      for (size_t i = 0; i <= FUZZ_MAX_TIMEOUT; ++i) {
+        MOZ_RELEASE_ASSERT(mOneShotTimersByDelay[i].empty(),
+                           "Timers remain at end of test.");
+      }
+    }
+
+    uint32_t GetRandomType() const
+    {
+      return rand() % (nsITimer::TYPE_REPEATING_PRECISE_CAN_SKIP + 1);
+    }
+
+    size_t CountOneShotTimers() const
+    {
+      size_t count = 0;
+      for (size_t i = 0; i <= FUZZ_MAX_TIMEOUT; ++i) {
+        count += mOneShotTimersByDelay[i].size();
+      }
+      return count;
+    }
+
+    void ScheduleOrCancelTimers()
+    {
+      if (mStopped) {
+        return;
+      }
+
+      const size_t numTimersDesired = (rand() % 100) + 100;
+      MOZ_RELEASE_ASSERT(numTimersDesired >= 100);
+      MOZ_RELEASE_ASSERT(numTimersDesired < 200);
+      int adjustment = numTimersDesired - mTimersOutstanding;
+
+      while (adjustment > 0) {
+        CreateRandomTimer();
+        --adjustment;
+      }
+
+      while (adjustment < 0) {
+        CancelRandomTimer();
+        ++adjustment;
+      }
+
+      MOZ_RELEASE_ASSERT(numTimersDesired == mTimersOutstanding);
+    }
+
+    void RescheduleSomeTimers()
+    {
+      if (mStopped) {
+        return;
+      }
+
+      static const size_t kNumRescheduled = 40;
+
+      // Reschedule some timers with a Cancel first.
+      for (size_t i = 0; i < kNumRescheduled; ++i) {
+        InitRandomTimer(CancelRandomTimer().get());
+      }
+      // Reschedule some timers without a Cancel first.
+      for (size_t i = 0; i < kNumRescheduled; ++i) {
+        InitRandomTimer(RemoveRandomTimer().get());
+      }
+    }
+
+    void CreateRandomTimer()
+    {
+      nsresult rv;
+      nsCOMPtr<nsITimer> timer = do_CreateInstance(NS_TIMER_CONTRACTID, &rv);
+      MOZ_RELEASE_ASSERT(NS_SUCCEEDED(rv), "Failed to create timer.");
+
+      rv = timer->SetTarget(static_cast<nsIEventTarget*>(mThread.get()));
+      MOZ_RELEASE_ASSERT(NS_SUCCEEDED(rv), "Failed to set target.");
+
+      InitRandomTimer(timer.get());
+    }
+
+    nsCOMPtr<nsITimer> CancelRandomTimer()
+    {
+      nsCOMPtr<nsITimer> timer(RemoveRandomTimer());
+      timer->Cancel();
+      return timer;
+    }
+
+    nsCOMPtr<nsITimer> RemoveRandomTimer()
+    {
+      MOZ_RELEASE_ASSERT(mTimersOutstanding);
+
+      if ((GetRandomType() == nsITimer::TYPE_ONE_SHOT && CountOneShotTimers())
+          || mRepeatingTimers.empty()) {
+        uint32_t delayToRemove = rand() % (FUZZ_MAX_TIMEOUT + 1);
+        while (mOneShotTimersByDelay[delayToRemove].empty()) {
+          // ++delayToRemove mod FUZZ_MAX_TIMEOUT + 1
+          delayToRemove = (delayToRemove + 1) % (FUZZ_MAX_TIMEOUT + 1);
+        }
+
+        uint32_t indexToRemove =
+          rand() % mOneShotTimersByDelay[delayToRemove].size();
+
+        for (auto it = mOneShotTimersByDelay[delayToRemove].begin();
+             it != mOneShotTimersByDelay[delayToRemove].end();
+             ++it) {
+          if (indexToRemove) {
+            --indexToRemove;
+            continue;
+          }
+
+          nsCOMPtr<nsITimer> removed = *it;
+          mOneShotTimersByDelay[delayToRemove].erase(it);
+          --mTimersOutstanding;
+          return removed;
+        }
+      } else {
+        size_t indexToRemove = rand() % mRepeatingTimers.size();
+        nsCOMPtr<nsITimer> removed(mRepeatingTimers[indexToRemove]);
+        mRepeatingTimers.erase(mRepeatingTimers.begin() + indexToRemove);
+        --mTimersOutstanding;
+        return removed;
+      }
+
+      MOZ_CRASH("Unable to remove a timer");
+    }
+
+    void InitRandomTimer(nsITimer* aTimer)
+    {
+      // Between 0 and FUZZ_MAX_TIMEOUT
+      uint32_t delay = rand() % (FUZZ_MAX_TIMEOUT + 1);
+      uint32_t type = GetRandomType();
+      nsresult rv = aTimer->InitWithCallback(this, delay, type);
+      MOZ_RELEASE_ASSERT(NS_SUCCEEDED(rv), "Failed to set timer.");
+
+      if (type == nsITimer::TYPE_ONE_SHOT) {
+        mOneShotTimersByDelay[delay].push_back(aTimer);
+      } else {
+        mRepeatingTimers.push_back(aTimer);
+      }
+      ++mTimersOutstanding;
+    }
+
+    void CancelRepeatingTimer(nsITimer* aTimer)
+    {
+      for (auto it = mRepeatingTimers.begin();
+           it != mRepeatingTimers.end();
+           ++it) {
+        if (it->get() == aTimer) {
+          mRepeatingTimers.erase(it);
+          aTimer->Cancel();
+          --mTimersOutstanding;
+          return;
+        }
+      }
+    }
+
+    nsCOMPtr<nsIThread> mThread;
+    // Scheduled timers, indexed by delay between 0-9 ms, in lists
+    // with most recently scheduled last.
+    std::list<nsCOMPtr<nsITimer>> mOneShotTimersByDelay[FUZZ_MAX_TIMEOUT + 1];
+    std::vector<nsCOMPtr<nsITimer>> mRepeatingTimers;
+    Atomic<bool> mStopped;
+    Atomic<size_t> mTimersOutstanding;
+};
+
+NS_IMPL_ISUPPORTS(FuzzTestThreadState, nsITimerCallback)
+
+TEST(Timers, FuzzTestTimers)
+{
+  static const size_t kNumThreads(10);
+  AutoTestThread threads[kNumThreads];
+  RefPtr<FuzzTestThreadState> threadStates[kNumThreads];
+
+  for (size_t i = 0; i < kNumThreads; ++i) {
+    threadStates[i] = new FuzzTestThreadState(&*threads[i]);
+    threadStates[i]->Start();
+  }
+
+  PR_Sleep(PR_MillisecondsToInterval(20000));
+
+  for (size_t i = 0; i < kNumThreads; ++i) {
+    threadStates[i]->Stop();
+  }
+
+  // Wait at most 10 seconds for all outstanding timers to pop
+  PRIntervalTime start = PR_IntervalNow();
+  for (auto& threadState : threadStates) {
+    while (threadState->HasTimersOutstanding()) {
+      uint32_t elapsedMs = PR_IntervalToMilliseconds(PR_IntervalNow() - start);
+      ASSERT_LE(elapsedMs, uint32_t(10000)) << "Timed out waiting for all timers to pop";
+      PR_Sleep(PR_MillisecondsToInterval(10));
+    }
+  }
+}
diff --git a/xpcom/tests/gtest/TestTokenizer.cpp b/xpcom/tests/gtest/TestTokenizer.cpp
new file mode 100644
index 000000000..283bbd3b8
--- /dev/null
+++ b/xpcom/tests/gtest/TestTokenizer.cpp
@@ -0,0 +1,1134 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Tokenizer.h"
+#include "mozilla/IncrementalTokenizer.h"
+#include "mozilla/Unused.h"
+#include "gtest/gtest.h"
+
+using namespace mozilla;
+
+static bool IsOperator(char const c)
+{
+  return c == '+' || c == '*';
+}
+
+static bool HttpHeaderCharacter(char const c)
+{
+  return (c >= 'a' && c <= 'z') ||
+         (c >= 'A' && c <= 'Z') ||
+         (c >= '0' && c <= '9') ||
+         (c == '_') ||
+         (c == '-');
+}
+
+TEST(Tokenizer, HTTPResponse)
+{
+  Tokenizer::Token t;
+
+  // Real life test, HTTP response
+
+  Tokenizer p(NS_LITERAL_CSTRING(
+    "HTTP/1.0 304 Not modified\r\n"
+    "ETag: hallo\r\n"
+    "Content-Length: 16\r\n"
+    "\r\n"
+    "This is the body"));
+
+  EXPECT_TRUE(p.CheckWord("HTTP"));
+  EXPECT_TRUE(p.CheckChar('/'));
+  EXPECT_TRUE(p.Check(Tokenizer::TOKEN_INTEGER, t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_INTEGER);
+  EXPECT_TRUE(t.AsInteger() == 1);
+  EXPECT_TRUE(p.CheckChar('.'));
+  EXPECT_TRUE(p.Check(Tokenizer::TOKEN_INTEGER, t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_INTEGER);
+  EXPECT_TRUE(t.AsInteger() == 0);
+  p.SkipWhites();
+
+  EXPECT_TRUE(p.Check(Tokenizer::TOKEN_INTEGER, t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_INTEGER);
+  EXPECT_TRUE(t.AsInteger() == 304);
+  p.SkipWhites();
+
+  p.Record();
+  while (p.Next(t) && t.Type() != Tokenizer::TOKEN_EOL);
+  EXPECT_FALSE(p.HasFailed());
+  nsAutoCString h;
+  p.Claim(h);
+  EXPECT_TRUE(h == "Not modified");
+
+  p.Record();
+  while (p.CheckChar(HttpHeaderCharacter));
+  p.Claim(h, Tokenizer::INCLUDE_LAST);
+  EXPECT_TRUE(h == "ETag");
+  p.SkipWhites();
+  EXPECT_TRUE(p.CheckChar(':'));
+  p.SkipWhites();
+  p.Record();
+  while (p.Next(t) && t.Type() != Tokenizer::TOKEN_EOL);
+  EXPECT_FALSE(p.HasFailed());
+  p.Claim(h);
+  EXPECT_TRUE(h == "hallo");
+
+  p.Record();
+  while (p.CheckChar(HttpHeaderCharacter));
+  p.Claim(h, Tokenizer::INCLUDE_LAST);
+  EXPECT_TRUE(h == "Content-Length");
+  p.SkipWhites();
+  EXPECT_TRUE(p.CheckChar(':'));
+  p.SkipWhites();
+  EXPECT_TRUE(p.Check(Tokenizer::TOKEN_INTEGER, t));
+  EXPECT_TRUE(t.AsInteger() == 16);
+  EXPECT_TRUE(p.CheckEOL());
+
+  EXPECT_TRUE(p.CheckEOL());
+
+  p.Record();
+  while (p.Next(t) && t.Type() != Tokenizer::TOKEN_EOF);
+  nsAutoCString b;
+  p.Claim(b);
+  EXPECT_TRUE(b == "This is the body");
+}
+
+TEST(Tokenizer, Main)
+{
+  Tokenizer::Token t;
+
+  // Synthetic code-specific test
+
+  Tokenizer p(NS_LITERAL_CSTRING("test123 ,15  \t*\r\n%xx,-15\r\r"));
+
+  EXPECT_TRUE(p.Next(t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_WORD);
+  EXPECT_TRUE(t.AsString() == "test123");
+
+  Tokenizer::Token u;
+  EXPECT_FALSE(p.Check(u));
+
+  EXPECT_FALSE(p.CheckChar('!'));
+
+  EXPECT_FALSE(p.Check(Tokenizer::Token::Number(123)));
+
+  EXPECT_TRUE(p.CheckWhite());
+
+  EXPECT_TRUE(p.CheckChar(','));
+
+  EXPECT_TRUE(p.Check(Tokenizer::Token::Number(15)));
+
+  p.Rollback();
+  EXPECT_TRUE(p.Check(Tokenizer::Token::Number(15)));
+
+  p.Rollback();
+  EXPECT_TRUE(p.Next(t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_INTEGER);
+  EXPECT_TRUE(t.AsInteger() == 15);
+
+  EXPECT_FALSE(p.CheckChar(IsOperator));
+
+  EXPECT_TRUE(p.CheckWhite());
+
+  p.SkipWhites();
+
+  EXPECT_FALSE(p.CheckWhite());
+
+  p.Rollback();
+
+  EXPECT_TRUE(p.CheckWhite());
+  EXPECT_TRUE(p.CheckWhite());
+
+  p.Record(Tokenizer::EXCLUDE_LAST);
+
+  EXPECT_TRUE(p.CheckChar(IsOperator));
+
+  p.Rollback();
+
+  EXPECT_TRUE(p.Next(t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_CHAR);
+  EXPECT_TRUE(t.AsChar() == '*');
+
+  EXPECT_TRUE(p.Next(t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_EOL);
+
+  EXPECT_TRUE(p.Next(t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_CHAR);
+  EXPECT_TRUE(t.AsChar() == '%');
+
+  nsAutoCString claim;
+  p.Claim(claim, Tokenizer::EXCLUDE_LAST);
+  EXPECT_TRUE(claim == "*\r\n");
+  p.Claim(claim, Tokenizer::INCLUDE_LAST);
+  EXPECT_TRUE(claim == "*\r\n%");
+
+  p.Rollback();
+  EXPECT_TRUE(p.CheckChar('%'));
+
+  p.Record(Tokenizer::INCLUDE_LAST);
+
+  EXPECT_FALSE(p.CheckWord("xy"));
+
+  EXPECT_TRUE(p.CheckWord("xx"));
+
+
+  p.Claim(claim, Tokenizer::INCLUDE_LAST);
+  EXPECT_TRUE(claim == "%xx");
+
+  EXPECT_TRUE(p.Next(t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_CHAR);
+  EXPECT_TRUE(t.AsChar() == ',');
+
+  EXPECT_TRUE(p.CheckChar('-'));
+
+  EXPECT_TRUE(p.Next(t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_INTEGER);
+  EXPECT_TRUE(t.AsInteger() == 15);
+
+  EXPECT_TRUE(p.Next(t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_EOL);
+
+  EXPECT_TRUE(p.Next(t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_EOL);
+
+  EXPECT_TRUE(p.Next(t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_EOF);
+
+  EXPECT_FALSE(p.Next(t));
+
+  p.Rollback();
+  EXPECT_TRUE(p.Next(t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_EOF);
+
+  EXPECT_FALSE(p.Next(t));
+
+  p.Rollback();
+  EXPECT_TRUE(p.CheckEOF());
+
+  EXPECT_FALSE(p.CheckEOF());
+}
+
+TEST(Tokenizer, SingleWord)
+{
+  // Single word with numbers in it test
+
+  Tokenizer p(NS_LITERAL_CSTRING("test123"));
+
+  EXPECT_TRUE(p.CheckWord("test123"));
+  EXPECT_TRUE(p.CheckEOF());
+}
+
+TEST(Tokenizer, EndingAfterNumber)
+{
+  // An end handling after a number
+
+  Tokenizer p(NS_LITERAL_CSTRING("123"));
+
+  EXPECT_FALSE(p.CheckWord("123"));
+  EXPECT_TRUE(p.Check(Tokenizer::Token::Number(123)));
+  EXPECT_TRUE(p.CheckEOF());
+}
+
+TEST(Tokenizer, BadInteger)
+{
+  Tokenizer::Token t;
+
+  // A bad integer test
+
+  Tokenizer p(NS_LITERAL_CSTRING("189234891274981758617846178651647620587135"));
+
+  EXPECT_TRUE(p.Next(t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_ERROR);
+  EXPECT_TRUE(p.CheckEOF());
+}
+
+TEST(Tokenizer, CheckExpectedTokenValue)
+{
+  Tokenizer::Token t;
+
+  // Check expected token value test
+
+  Tokenizer p(NS_LITERAL_CSTRING("blue velvet"));
+
+  EXPECT_FALSE(p.Check(Tokenizer::TOKEN_INTEGER, t));
+
+  EXPECT_TRUE(p.Check(Tokenizer::TOKEN_WORD, t));
+  EXPECT_TRUE(t.AsString() == "blue");
+
+  EXPECT_FALSE(p.Check(Tokenizer::TOKEN_WORD, t));
+
+  EXPECT_TRUE(p.CheckWhite());
+
+  EXPECT_TRUE(p.Check(Tokenizer::TOKEN_WORD, t));
+  EXPECT_TRUE(t.AsString() == "velvet");
+
+  EXPECT_TRUE(p.CheckEOF());
+
+  EXPECT_FALSE(p.Next(t));
+}
+
+TEST(Tokenizer, HasFailed)
+{
+  Tokenizer::Token t;
+
+  // HasFailed test
+
+  Tokenizer p1(NS_LITERAL_CSTRING("a b"));
+
+  while (p1.Next(t) && t.Type() != Tokenizer::TOKEN_CHAR);
+  EXPECT_TRUE(p1.HasFailed());
+
+
+  Tokenizer p2(NS_LITERAL_CSTRING("a b ?!c"));
+
+  EXPECT_FALSE(p2.CheckChar('c'));
+  EXPECT_TRUE(p2.HasFailed());
+  EXPECT_TRUE(p2.CheckChar(HttpHeaderCharacter));
+  EXPECT_FALSE(p2.HasFailed());
+  p2.SkipWhites();
+  EXPECT_FALSE(p2.HasFailed());
+  EXPECT_FALSE(p2.CheckChar('c'));
+  EXPECT_TRUE(p2.HasFailed());
+  EXPECT_TRUE(p2.Next(t));
+  EXPECT_FALSE(p2.HasFailed());
+  EXPECT_TRUE(p2.Next(t));
+  EXPECT_FALSE(p2.HasFailed());
+  EXPECT_FALSE(p2.CheckChar('c'));
+  EXPECT_TRUE(p2.HasFailed());
+  EXPECT_TRUE(p2.Check(Tokenizer::TOKEN_CHAR, t));
+  EXPECT_FALSE(p2.HasFailed());
+  EXPECT_FALSE(p2.CheckChar('#'));
+  EXPECT_TRUE(p2.HasFailed());
+  t = Tokenizer::Token::Char('!');
+  EXPECT_TRUE(p2.Check(t));
+  EXPECT_FALSE(p2.HasFailed());
+
+  while (p2.Next(t) && t.Type() != Tokenizer::TOKEN_CHAR);
+  EXPECT_TRUE(p2.HasFailed());
+}
+
+TEST(Tokenizer, Construction)
+{
+  {
+    nsCString a("test");
+    Tokenizer p1(a);
+    EXPECT_TRUE(p1.CheckWord("test"));
+    EXPECT_TRUE(p1.CheckEOF());
+  }
+
+  {
+    nsAutoCString a("test");
+    Tokenizer p1(a);
+    EXPECT_TRUE(p1.CheckWord("test"));
+    EXPECT_TRUE(p1.CheckEOF());
+  }
+
+  {
+    static const char _a[] = "test";
+    nsDependentCString a(_a);
+    Tokenizer p1(a);
+    EXPECT_TRUE(p1.CheckWord("test"));
+    EXPECT_TRUE(p1.CheckEOF());
+  }
+
+  {
+    static const char* _a = "test";
+    nsDependentCString a(_a);
+    Tokenizer p1(a);
+    EXPECT_TRUE(p1.CheckWord("test"));
+    EXPECT_TRUE(p1.CheckEOF());
+  }
+
+  {
+    Tokenizer p1(nsDependentCString("test"));
+    EXPECT_TRUE(p1.CheckWord("test"));
+    EXPECT_TRUE(p1.CheckEOF());
+  }
+
+  {
+    Tokenizer p1(NS_LITERAL_CSTRING("test"));
+    EXPECT_TRUE(p1.CheckWord("test"));
+    EXPECT_TRUE(p1.CheckEOF());
+  }
+
+  {
+    Tokenizer p1("test");
+    EXPECT_TRUE(p1.CheckWord("test"));
+    EXPECT_TRUE(p1.CheckEOF());
+  }
+}
+
+TEST(Tokenizer, Customization)
+{
+  Tokenizer p1(NS_LITERAL_CSTRING("test-custom*words and\tdefault-whites"), nullptr, "-*");
+  EXPECT_TRUE(p1.CheckWord("test-custom*words"));
+  EXPECT_TRUE(p1.CheckWhite());
+  EXPECT_TRUE(p1.CheckWord("and"));
+  EXPECT_TRUE(p1.CheckWhite());
+  EXPECT_TRUE(p1.CheckWord("default-whites"));
+
+  Tokenizer p2(NS_LITERAL_CSTRING("test, custom,whites"), ", ");
+  EXPECT_TRUE(p2.CheckWord("test"));
+  EXPECT_TRUE(p2.CheckWhite());
+  EXPECT_TRUE(p2.CheckWhite());
+  EXPECT_TRUE(p2.CheckWord("custom"));
+  EXPECT_TRUE(p2.CheckWhite());
+  EXPECT_TRUE(p2.CheckWord("whites"));
+
+  Tokenizer p3(NS_LITERAL_CSTRING("test, custom, whites-and#word-chars"), ",", "-#");
+  EXPECT_TRUE(p3.CheckWord("test"));
+  EXPECT_TRUE(p3.CheckWhite());
+  EXPECT_FALSE(p3.CheckWhite());
+  EXPECT_TRUE(p3.CheckChar(' '));
+  EXPECT_TRUE(p3.CheckWord("custom"));
+  EXPECT_TRUE(p3.CheckWhite());
+  EXPECT_FALSE(p3.CheckWhite());
+  EXPECT_TRUE(p3.CheckChar(' '));
+  EXPECT_TRUE(p3.CheckWord("whites-and#word-chars"));
+}
+
+TEST(Tokenizer, ShortcutChecks)
+{
+  Tokenizer p("test1 test2,123");
+
+  nsAutoCString test1;
+  nsDependentCSubstring test2;
+  char comma;
+  uint32_t integer;
+
+  EXPECT_TRUE(p.ReadWord(test1));
+  EXPECT_TRUE(test1 == "test1");
+  p.SkipWhites();
+  EXPECT_TRUE(p.ReadWord(test2));
+  EXPECT_TRUE(test2 == "test2");
+  EXPECT_TRUE(p.ReadChar(&comma));
+  EXPECT_TRUE(comma == ',');
+  EXPECT_TRUE(p.ReadInteger(&integer));
+  EXPECT_TRUE(integer == 123);
+  EXPECT_TRUE(p.CheckEOF());
+}
+
+static bool ABChar(const char aChar)
+{
+  return aChar == 'a' || aChar == 'b';
+}
+
+TEST(Tokenizer, ReadCharClassified)
+{
+  Tokenizer p("abc");
+
+  char c;
+  EXPECT_TRUE(p.ReadChar(ABChar, &c));
+  EXPECT_TRUE(c == 'a');
+  EXPECT_TRUE(p.ReadChar(ABChar, &c));
+  EXPECT_TRUE(c == 'b');
+  EXPECT_FALSE(p.ReadChar(ABChar, &c));
+  nsDependentCSubstring w;
+  EXPECT_TRUE(p.ReadWord(w));
+  EXPECT_TRUE(w == "c");
+  EXPECT_TRUE(p.CheckEOF());
+}
+
+TEST(Tokenizer, ClaimSubstring)
+{
+  Tokenizer p(" abc ");
+
+  EXPECT_TRUE(p.CheckWhite());
+
+  p.Record();
+  EXPECT_TRUE(p.CheckWord("abc"));
+  nsDependentCSubstring v;
+  p.Claim(v, Tokenizer::INCLUDE_LAST);
+  EXPECT_TRUE(v == "abc");
+  EXPECT_TRUE(p.CheckWhite());
+  EXPECT_TRUE(p.CheckEOF());
+}
+
+TEST(Tokenizer, Fragment)
+{
+  const char str[] = "ab;cd:10 ";
+  Tokenizer p(str);
+  nsDependentCSubstring f;
+
+  Tokenizer::Token t1, t2;
+
+  EXPECT_TRUE(p.Next(t1));
+  EXPECT_TRUE(t1.Type() == Tokenizer::TOKEN_WORD);
+  EXPECT_TRUE(t1.Fragment() == "ab");
+  EXPECT_TRUE(t1.Fragment().BeginReading() == &str[0]);
+
+  p.Rollback();
+  EXPECT_TRUE(p.Check(Tokenizer::TOKEN_WORD, t2));
+  EXPECT_TRUE(t2.Fragment() == "ab");
+  EXPECT_TRUE(t2.Fragment().BeginReading() == &str[0]);
+
+
+  EXPECT_TRUE(p.Next(t1));
+  EXPECT_TRUE(t1.Type() == Tokenizer::TOKEN_CHAR);
+  EXPECT_TRUE(t1.Fragment() == ";");
+  EXPECT_TRUE(t1.Fragment().BeginReading() == &str[2]);
+
+  p.Rollback();
+  EXPECT_TRUE(p.Check(Tokenizer::TOKEN_CHAR, t2));
+  EXPECT_TRUE(t2.Fragment() == ";");
+  EXPECT_TRUE(t2.Fragment().BeginReading() == &str[2]);
+
+
+  EXPECT_TRUE(p.Check(Tokenizer::TOKEN_WORD, t2));
+  EXPECT_TRUE(t2.Fragment() == "cd");
+  EXPECT_TRUE(t2.Fragment().BeginReading() == &str[3]);
+
+  p.Rollback();
+  EXPECT_TRUE(p.Next(t1));
+  EXPECT_TRUE(t1.Type() == Tokenizer::TOKEN_WORD);
+  EXPECT_TRUE(t1.Fragment() == "cd");
+  EXPECT_TRUE(t1.Fragment().BeginReading() == &str[3]);
+
+
+  EXPECT_TRUE(p.Check(Tokenizer::TOKEN_CHAR, t2));
+  EXPECT_TRUE(t2.Fragment() == ":");
+  EXPECT_TRUE(t2.Fragment().BeginReading() == &str[5]);
+
+  p.Rollback();
+  EXPECT_TRUE(p.Next(t1));
+  EXPECT_TRUE(t1.Type() == Tokenizer::TOKEN_CHAR);
+  EXPECT_TRUE(t1.Fragment() == ":");
+  EXPECT_TRUE(t1.Fragment().BeginReading() == &str[5]);
+
+
+  EXPECT_TRUE(p.Next(t1));
+  EXPECT_TRUE(t1.Type() == Tokenizer::TOKEN_INTEGER);
+  EXPECT_TRUE(t1.Fragment() == "10");
+  EXPECT_TRUE(t1.Fragment().BeginReading() == &str[6]);
+
+
+  EXPECT_TRUE(p.Check(Tokenizer::TOKEN_WS, t2));
+  EXPECT_TRUE(t2.Fragment() == " ");
+  EXPECT_TRUE(t2.Fragment().BeginReading() == &str[8]);
+
+
+  EXPECT_TRUE(p.Check(Tokenizer::TOKEN_EOF, t1));
+  EXPECT_TRUE(t1.Fragment() == "");
+  EXPECT_TRUE(t1.Fragment().BeginReading() == &str[9]);
+}
+
+TEST(Tokenizer, SkipWhites)
+{
+  Tokenizer p("Text1 \nText2 \nText3\n Text4\n ");
+
+  EXPECT_TRUE(p.CheckWord("Text1"));
+  p.SkipWhites();
+  EXPECT_TRUE(p.CheckEOL());
+
+  EXPECT_TRUE(p.CheckWord("Text2"));
+  p.SkipWhites(Tokenizer::INCLUDE_NEW_LINE);
+
+  EXPECT_TRUE(p.CheckWord("Text3"));
+  p.SkipWhites();
+  EXPECT_TRUE(p.CheckEOL());
+  p.SkipWhites();
+
+  EXPECT_TRUE(p.CheckWord("Text4"));
+  p.SkipWhites(Tokenizer::INCLUDE_NEW_LINE);
+  EXPECT_TRUE(p.CheckEOF());
+}
+
+TEST(Tokenizer, SkipCustomWhites)
+{
+  Tokenizer p("Text1 \n\r\t.Text2 \n\r\t.", " \n\r\t.");
+
+  EXPECT_TRUE(p.CheckWord("Text1"));
+  p.SkipWhites();
+  EXPECT_TRUE(p.CheckWord("Text2"));
+  EXPECT_TRUE(p.CheckWhite());
+  EXPECT_TRUE(p.CheckWhite());
+  EXPECT_TRUE(p.CheckWhite());
+  EXPECT_TRUE(p.CheckWhite());
+  EXPECT_TRUE(p.CheckWhite());
+  EXPECT_TRUE(p.CheckEOF());
+}
+
+TEST(Tokenizer, IntegerReading)
+{
+#define INT_6_BITS                 64U
+#define INT_30_BITS                1073741824UL
+#define INT_32_BITS                4294967295UL
+#define INT_50_BITS                1125899906842624ULL
+#define STR_INT_MORE_THAN_64_BITS "922337203685477580899"
+
+  {
+    Tokenizer p(NS_STRINGIFY(INT_6_BITS));
+    uint8_t u8;
+    uint16_t u16;
+    uint32_t u32;
+    uint64_t u64;
+    EXPECT_TRUE(p.ReadInteger(&u8));
+    EXPECT_TRUE(u8 == INT_6_BITS);
+    p.Rollback();
+    EXPECT_TRUE(p.ReadInteger(&u16));
+    EXPECT_TRUE(u16 == INT_6_BITS);
+    p.Rollback();
+    EXPECT_TRUE(p.ReadInteger(&u32));
+    EXPECT_TRUE(u32 == INT_6_BITS);
+    p.Rollback();
+    EXPECT_TRUE(p.ReadInteger(&u64));
+    EXPECT_TRUE(u64 == INT_6_BITS);
+
+    p.Rollback();
+
+    int8_t s8;
+    int16_t s16;
+    int32_t s32;
+    int64_t s64;
+    EXPECT_TRUE(p.ReadInteger(&s8));
+    EXPECT_TRUE(s8 == INT_6_BITS);
+    p.Rollback();
+    EXPECT_TRUE(p.ReadInteger(&s16));
+    EXPECT_TRUE(s16 == INT_6_BITS);
+    p.Rollback();
+    EXPECT_TRUE(p.ReadInteger(&s32));
+    EXPECT_TRUE(s32 == INT_6_BITS);
+    p.Rollback();
+    EXPECT_TRUE(p.ReadInteger(&s64));
+    EXPECT_TRUE(s64 == INT_6_BITS);
+
+    EXPECT_TRUE(p.CheckWord("U"));
+    EXPECT_TRUE(p.CheckEOF());
+  }
+
+  {
+    Tokenizer p(NS_STRINGIFY(INT_30_BITS));
+    uint8_t u8;
+    uint16_t u16;
+    uint32_t u32;
+    uint64_t u64;
+    EXPECT_FALSE(p.ReadInteger(&u8));
+    EXPECT_FALSE(p.ReadInteger(&u16));
+    EXPECT_TRUE(p.ReadInteger(&u32));
+    EXPECT_TRUE(u32 == INT_30_BITS);
+    p.Rollback();
+    EXPECT_TRUE(p.ReadInteger(&u64));
+    EXPECT_TRUE(u64 == INT_30_BITS);
+
+    p.Rollback();
+
+    int8_t s8;
+    int16_t s16;
+    int32_t s32;
+    int64_t s64;
+    EXPECT_FALSE(p.ReadInteger(&s8));
+    EXPECT_FALSE(p.ReadInteger(&s16));
+    EXPECT_TRUE(p.ReadInteger(&s32));
+    EXPECT_TRUE(s32 == INT_30_BITS);
+    p.Rollback();
+    EXPECT_TRUE(p.ReadInteger(&s64));
+    EXPECT_TRUE(s64 == INT_30_BITS);
+    EXPECT_TRUE(p.CheckWord("UL"));
+    EXPECT_TRUE(p.CheckEOF());
+  }
+
+  {
+    Tokenizer p(NS_STRINGIFY(INT_32_BITS));
+    uint32_t u32;
+    int32_t s32;
+    EXPECT_FALSE(p.ReadInteger(&s32));
+    EXPECT_TRUE(p.ReadInteger(&u32));
+    EXPECT_TRUE(u32 == INT_32_BITS);
+    EXPECT_TRUE(p.CheckWord("UL"));
+    EXPECT_TRUE(p.CheckEOF());
+  }
+
+  {
+    Tokenizer p(NS_STRINGIFY(INT_50_BITS));
+    uint8_t u8;
+    uint16_t u16;
+    uint32_t u32;
+    uint64_t u64;
+    EXPECT_FALSE(p.ReadInteger(&u8));
+    EXPECT_FALSE(p.ReadInteger(&u16));
+    EXPECT_FALSE(p.ReadInteger(&u32));
+    EXPECT_TRUE(p.ReadInteger(&u64));
+    EXPECT_TRUE(u64 == INT_50_BITS);
+    EXPECT_TRUE(p.CheckWord("ULL"));
+    EXPECT_TRUE(p.CheckEOF());
+  }
+
+  {
+    Tokenizer p(STR_INT_MORE_THAN_64_BITS);
+    int64_t i;
+    EXPECT_FALSE(p.ReadInteger(&i));
+    uint64_t u;
+    EXPECT_FALSE(p.ReadInteger(&u));
+    EXPECT_FALSE(p.CheckEOF());
+  }
+}
+
+TEST(Tokenizer, ReadUntil)
+{
+  Tokenizer p("Hello;test 4,");
+  nsDependentCSubstring f;
+  EXPECT_TRUE(p.ReadUntil(Tokenizer::Token::Char(';'), f));
+  EXPECT_TRUE(f == "Hello");
+  p.Rollback();
+
+  EXPECT_TRUE(p.ReadUntil(Tokenizer::Token::Char(';'), f, Tokenizer::INCLUDE_LAST));
+  EXPECT_TRUE(f == "Hello;");
+  p.Rollback();
+
+  EXPECT_FALSE(p.ReadUntil(Tokenizer::Token::Char('!'), f));
+  EXPECT_TRUE(f == "Hello;test 4,");
+  p.Rollback();
+
+  EXPECT_TRUE(p.ReadUntil(Tokenizer::Token::Word(NS_LITERAL_CSTRING("test")), f));
+  EXPECT_TRUE(f == "Hello;");
+  p.Rollback();
+
+  EXPECT_TRUE(p.ReadUntil(Tokenizer::Token::Word(NS_LITERAL_CSTRING("test")), f, Tokenizer::INCLUDE_LAST));
+  EXPECT_TRUE(f == "Hello;test");
+  EXPECT_TRUE(p.ReadUntil(Tokenizer::Token::Char(','), f));
+  EXPECT_TRUE(f == " 4");
+}
+
+TEST(Tokenizer, SkipUntil)
+{
+  {
+    Tokenizer p("test1,test2,,,test3");
+
+    p.SkipUntil(Tokenizer::Token::Char(','));
+    EXPECT_TRUE(p.CheckChar(','));
+    EXPECT_TRUE(p.CheckWord("test2"));
+
+    p.SkipUntil(Tokenizer::Token::Char(',')); // must not move
+    EXPECT_TRUE(p.CheckChar(',')); // check the first comma of the ',,,' string
+
+    p.Rollback(); // moves cursor back to the first comma of the ',,,' string
+
+    p.SkipUntil(Tokenizer::Token::Char(',')); // must not move, we are on the ',' char
+    EXPECT_TRUE(p.CheckChar(','));
+    EXPECT_TRUE(p.CheckChar(','));
+    EXPECT_TRUE(p.CheckChar(','));
+    EXPECT_TRUE(p.CheckWord("test3"));
+    p.Rollback();
+
+    p.SkipUntil(Tokenizer::Token::Char(','));
+    EXPECT_TRUE(p.CheckEOF());
+  }
+
+  {
+    Tokenizer p("test0,test1,test2");
+
+    p.SkipUntil(Tokenizer::Token::Char(','));
+    EXPECT_TRUE(p.CheckChar(','));
+
+    p.SkipUntil(Tokenizer::Token::Char(','));
+    p.Rollback();
+
+    EXPECT_TRUE(p.CheckWord("test1"));
+    EXPECT_TRUE(p.CheckChar(','));
+
+    p.SkipUntil(Tokenizer::Token::Char(','));
+    p.Rollback();
+
+    EXPECT_TRUE(p.CheckWord("test2"));
+    EXPECT_TRUE(p.CheckEOF());
+  }
+}
+
+TEST(Tokenizer, Custom)
+{
+  Tokenizer p("aaaaaacustom-1\r,custom-1,Custom-1,Custom-1,00custom-2xxxx,CUSTOM-2");
+
+  Tokenizer::Token c1 = p.AddCustomToken("custom-1", Tokenizer::CASE_INSENSITIVE);
+  Tokenizer::Token c2 = p.AddCustomToken("custom-2", Tokenizer::CASE_SENSITIVE);
+
+  // It's expected to NOT FIND the custom token if it's not on an edge
+  // between other recognizable tokens.
+  EXPECT_TRUE(p.CheckWord("aaaaaacustom"));
+  EXPECT_TRUE(p.CheckChar('-'));
+  EXPECT_TRUE(p.Check(Tokenizer::Token::Number(1)));
+  EXPECT_TRUE(p.CheckEOL());
+  EXPECT_TRUE(p.CheckChar(','));
+
+  EXPECT_TRUE(p.Check(c1));
+  EXPECT_TRUE(p.CheckChar(','));
+
+  EXPECT_TRUE(p.Check(c1));
+  EXPECT_TRUE(p.CheckChar(','));
+
+  p.EnableCustomToken(c1, false);
+  EXPECT_TRUE(p.CheckWord("Custom"));
+  EXPECT_TRUE(p.CheckChar('-'));
+  EXPECT_TRUE(p.Check(Tokenizer::Token::Number(1)));
+  EXPECT_TRUE(p.CheckChar(','));
+
+  EXPECT_TRUE(p.Check(Tokenizer::Token::Number(0)));
+  EXPECT_TRUE(p.Check(c2));
+  EXPECT_TRUE(p.CheckWord("xxxx"));
+  EXPECT_TRUE(p.CheckChar(','));
+
+  EXPECT_TRUE(p.CheckWord("CUSTOM"));
+  EXPECT_TRUE(p.CheckChar('-'));
+  EXPECT_TRUE(p.Check(Tokenizer::Token::Number(2)));
+
+  EXPECT_TRUE(p.CheckEOF());
+}
+
+TEST(Tokenizer, CustomRaw)
+{
+  Tokenizer p("aaaaaacustom-1\r,custom-1,Custom-1,Custom-1,00custom-2xxxx,CUSTOM-2");
+
+  Tokenizer::Token c1 = p.AddCustomToken("custom-1", Tokenizer::CASE_INSENSITIVE);
+  Tokenizer::Token c2 = p.AddCustomToken("custom-2", Tokenizer::CASE_SENSITIVE);
+
+  // In this mode it's expected to find all custom tokens among any kind of input.
+  p.SetTokenizingMode(Tokenizer::Mode::CUSTOM_ONLY);
+
+  Tokenizer::Token t;
+
+  EXPECT_TRUE(p.Next(t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_RAW);
+  EXPECT_TRUE(t.Fragment().EqualsLiteral("aaaaaa"));
+
+  EXPECT_TRUE(p.Check(c1));
+
+  EXPECT_TRUE(p.Next(t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_RAW);
+  EXPECT_TRUE(t.Fragment().EqualsLiteral("\r,"));
+
+  EXPECT_TRUE(p.Check(c1));
+
+  EXPECT_TRUE(p.Next(t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_RAW);
+  EXPECT_TRUE(t.Fragment().EqualsLiteral(","));
+
+  EXPECT_TRUE(p.Check(c1));
+
+  EXPECT_TRUE(p.Next(t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_RAW);
+  EXPECT_TRUE(t.Fragment().EqualsLiteral(","));
+
+  EXPECT_TRUE(p.Check(c1));
+
+  EXPECT_TRUE(p.Next(t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_RAW);
+  EXPECT_TRUE(t.Fragment().EqualsLiteral(",00"));
+
+  EXPECT_TRUE(p.Check(c2));
+
+  EXPECT_TRUE(p.Next(t));
+  EXPECT_TRUE(t.Type() == Tokenizer::TOKEN_RAW);
+  EXPECT_TRUE(t.Fragment().EqualsLiteral("xxxx,CUSTOM-2"));
+
+  EXPECT_TRUE(p.CheckEOF());
+}
+
+TEST(Tokenizer, Incremental)
+{
+  typedef TokenizerBase::Token Token;
+
+  int test = 0;
+  IncrementalTokenizer i([&](Token const& t, IncrementalTokenizer& i) -> nsresult
+  {
+    switch (++test) {
+      case 1: EXPECT_TRUE(t.Equals(Token::Word(NS_LITERAL_CSTRING("test1")))); break;
+      case 2: EXPECT_TRUE(t.Equals(Token::Char(','))); break;
+      case 3: EXPECT_TRUE(t.Equals(Token::Word(NS_LITERAL_CSTRING("test2")))); break;
+      case 4: EXPECT_TRUE(t.Equals(Token::Char(','))); break;
+      case 5: EXPECT_TRUE(t.Equals(Token::Char(','))); break;
+      case 6: EXPECT_TRUE(t.Equals(Token::Char(','))); break;
+      case 7: EXPECT_TRUE(t.Equals(Token::Word(NS_LITERAL_CSTRING("test3")))); break;
+      case 8: EXPECT_TRUE(t.Equals(Token::EndOfFile())); break;
+    }
+
+    return NS_OK;
+  });
+
+  NS_NAMED_LITERAL_CSTRING(input, "test1,test2,,,test3");
+  auto cur = input.BeginReading();
+  auto end = input.EndReading();
+  for (; cur < end; ++cur) {
+    i.FeedInput(nsDependentCSubstring(cur, 1));
+  }
+
+  EXPECT_TRUE(test == 6);
+  i.FinishInput();
+  EXPECT_TRUE(test == 8);
+}
+
+TEST(Tokenizer, IncrementalRollback)
+{
+  typedef TokenizerBase::Token Token;
+
+  int test = 0;
+  IncrementalTokenizer i([&](Token const& t, IncrementalTokenizer& i) -> nsresult
+  {
+    switch (++test) {
+      case 1: EXPECT_TRUE(t.Equals(Token::Word(NS_LITERAL_CSTRING("test1")))); break;
+      case 2: EXPECT_TRUE(t.Equals(Token::Char(','))); break;
+      case 3: EXPECT_TRUE(t.Equals(Token::Word(NS_LITERAL_CSTRING("test2"))));
+        i.Rollback(); // so that we get the token again
+        break;
+      case 4: EXPECT_TRUE(t.Equals(Token::Word(NS_LITERAL_CSTRING("test2")))); break;
+      case 5: EXPECT_TRUE(t.Equals(Token::Char(','))); break;
+      case 6: EXPECT_TRUE(t.Equals(Token::Char(','))); break;
+      case 7: EXPECT_TRUE(t.Equals(Token::Char(','))); break;
+      case 8: EXPECT_TRUE(t.Equals(Token::Word(NS_LITERAL_CSTRING("test3")))); break;
+      case 9: EXPECT_TRUE(t.Equals(Token::EndOfFile())); break;
+    }
+
+    return NS_OK;
+  });
+
+  NS_NAMED_LITERAL_CSTRING(input, "test1,test2,,,test3");
+  auto cur = input.BeginReading();
+  auto end = input.EndReading();
+  for (; cur < end; ++cur) {
+    i.FeedInput(nsDependentCSubstring(cur, 1));
+  }
+
+  EXPECT_TRUE(test == 7);
+  i.FinishInput();
+  EXPECT_TRUE(test == 9);
+}
+
+TEST(Tokenizer, IncrementalNeedMoreInput)
+{
+  typedef TokenizerBase::Token Token;
+
+  int test = 0;
+  IncrementalTokenizer i([&](Token const& t, IncrementalTokenizer& i) -> nsresult
+  {
+    Token t2;
+    switch (++test) {
+    case 1:
+      EXPECT_TRUE(t.Equals(Token::Word(NS_LITERAL_CSTRING("a"))));
+      break;
+    case 2:
+    case 3:
+    case 4:
+    case 5:
+      EXPECT_TRUE(t.Equals(Token::Whitespace()));
+      if (i.Next(t2)) {
+        EXPECT_TRUE(test == 5);
+        EXPECT_TRUE(t2.Equals(Token::Word(NS_LITERAL_CSTRING("bb"))));
+      } else {
+        EXPECT_TRUE(test < 5);
+        i.NeedMoreInput();
+      }
+      break;
+    case 6:
+      EXPECT_TRUE(t.Equals(Token::Char(',')));
+      break;
+    case 7:
+      EXPECT_TRUE(t.Equals(Token::Word(NS_LITERAL_CSTRING("c"))));
+      return NS_ERROR_FAILURE;
+    default:
+      EXPECT_TRUE(false);
+      break;
+    }
+
+    return NS_OK;
+  });
+
+  NS_NAMED_LITERAL_CSTRING(input, "a bb,c");
+  auto cur = input.BeginReading();
+  auto end = input.EndReading();
+
+  nsresult rv;
+  for (; cur < end; ++cur) {
+    rv = i.FeedInput(nsDependentCSubstring(cur, 1));
+    if (NS_FAILED(rv)) {
+      break;
+    }
+  }
+
+  EXPECT_TRUE(rv == NS_OK);
+  EXPECT_TRUE(test == 6);
+
+  rv = i.FinishInput();
+  EXPECT_TRUE(rv == NS_ERROR_FAILURE);
+  EXPECT_TRUE(test == 7);
+}
+
+TEST(Tokenizer, IncrementalCustom)
+{
+  typedef TokenizerBase::Token Token;
+
+  int test = 0;
+  Token custom;
+  IncrementalTokenizer i([&](Token const& t, IncrementalTokenizer& i) -> nsresult
+  {
+    switch (++test) {
+      case 1: EXPECT_TRUE(t.Equals(custom)); break;
+      case 2: EXPECT_TRUE(t.Equals(Token::Word(NS_LITERAL_CSTRING("bla")))); break;
+      case 3: EXPECT_TRUE(t.Equals(Token::EndOfFile())); break;
+    }
+
+    return NS_OK;
+  }, nullptr, "-");
+
+  custom = i.AddCustomToken("some-test", Tokenizer::CASE_SENSITIVE);
+  i.FeedInput(NS_LITERAL_CSTRING("some-"));
+  EXPECT_TRUE(test == 0);
+  i.FeedInput(NS_LITERAL_CSTRING("tes"));
+  EXPECT_TRUE(test == 0);
+  i.FeedInput(NS_LITERAL_CSTRING("tbla"));
+  EXPECT_TRUE(test == 1);
+  i.FinishInput();
+  EXPECT_TRUE(test == 3);
+}
+
+TEST(Tokenizer, IncrementalCustomRaw)
+{
+  typedef TokenizerBase::Token Token;
+
+  int test = 0;
+  Token custom;
+  IncrementalTokenizer i([&](Token const& t, IncrementalTokenizer& i) -> nsresult
+  {
+    switch (++test) {
+      case 1: EXPECT_TRUE(t.Fragment().EqualsLiteral("test1,")); break;
+      case 2: EXPECT_TRUE(t.Equals(custom)); break;
+      case 3: EXPECT_TRUE(t.Fragment().EqualsLiteral("!,,test3"));
+        i.Rollback();
+        i.SetTokenizingMode(Tokenizer::Mode::FULL);
+        break;
+      case 4: EXPECT_TRUE(t.Equals(Token::Char('!')));
+        i.SetTokenizingMode(Tokenizer::Mode::CUSTOM_ONLY);
+        break;
+      case 5: EXPECT_TRUE(t.Fragment().EqualsLiteral(",,test3")); break;
+      case 6: EXPECT_TRUE(t.Equals(custom)); break;
+      case 7: EXPECT_TRUE(t.Fragment().EqualsLiteral("tes")); break;
+      case 8: EXPECT_TRUE(t.Equals(Token::EndOfFile())); break;
+    }
+
+    return NS_OK;
+  });
+
+  custom = i.AddCustomToken("test2", Tokenizer::CASE_SENSITIVE);
+  i.SetTokenizingMode(Tokenizer::Mode::CUSTOM_ONLY);
+
+  NS_NAMED_LITERAL_CSTRING(input, "test1,test2!,,test3test2tes");
+  auto cur = input.BeginReading();
+  auto end = input.EndReading();
+  for (; cur < end; ++cur) {
+    i.FeedInput(nsDependentCSubstring(cur, 1));
+  }
+
+  EXPECT_TRUE(test == 6);
+  i.FinishInput();
+  EXPECT_TRUE(test == 8);
+}
+
+TEST(Tokenizer, IncrementalCustomRemove)
+{
+  typedef TokenizerBase::Token Token;
+
+  int test = 0;
+  Token custom;
+  IncrementalTokenizer i([&](Token const& t, IncrementalTokenizer& i) -> nsresult
+  {
+    switch (++test) {
+      case 1: EXPECT_TRUE(t.Equals(custom));
+        i.RemoveCustomToken(custom);
+        break;
+      case 2: EXPECT_FALSE(t.Equals(custom)); break;
+      case 3: EXPECT_TRUE(t.Equals(Token::EndOfFile())); break;
+    }
+
+    return NS_OK;
+  });
+
+  custom = i.AddCustomToken("custom1", Tokenizer::CASE_SENSITIVE);
+
+  NS_NAMED_LITERAL_CSTRING(input, "custom1custom1");
+  i.FeedInput(input);
+  EXPECT_TRUE(test == 1);
+  i.FinishInput();
+  EXPECT_TRUE(test == 3);
+}
+
+TEST(Tokenizer, IncrementalBuffering1)
+{
+  typedef TokenizerBase::Token Token;
+
+  int test = 0;
+  Token custom;
+  nsDependentCSubstring observedFragment;
+  IncrementalTokenizer i([&](Token const& t, IncrementalTokenizer& i) -> nsresult
+  {
+    switch (++test) {
+      case 1: EXPECT_TRUE(t.Fragment().EqualsLiteral("012")); break;
+      case 2: EXPECT_TRUE(t.Fragment().EqualsLiteral("3456789")); break;
+      case 3: EXPECT_TRUE(t.Equals(custom)); break;
+      case 4: EXPECT_TRUE(t.Fragment().EqualsLiteral("qwe")); break;
+      case 5: EXPECT_TRUE(t.Fragment().EqualsLiteral("rt")); break;
+      case 6: EXPECT_TRUE(t.Equals(Token::EndOfFile())); break;
+    }
+
+    observedFragment.Rebind(t.Fragment().BeginReading(),
+                            t.Fragment().Length());
+    return NS_OK;
+  }, nullptr, nullptr, 3);
+
+  custom = i.AddCustomToken("aaa", Tokenizer::CASE_SENSITIVE);
+  // This externally unused token is added only to check the internal algorithm
+  // does work correctly as expected when there are two different length tokens.
+  Unused << i.AddCustomToken("bb", Tokenizer::CASE_SENSITIVE);
+  i.SetTokenizingMode(Tokenizer::Mode::CUSTOM_ONLY);
+
+  i.FeedInput(NS_LITERAL_CSTRING("01234"));
+  EXPECT_TRUE(test == 1);
+  EXPECT_TRUE(observedFragment.EqualsLiteral("012"));
+
+  i.FeedInput(NS_LITERAL_CSTRING("5"));
+  EXPECT_TRUE(test == 1);
+  i.FeedInput(NS_LITERAL_CSTRING("6789aa"));
+  EXPECT_TRUE(test == 2);
+  EXPECT_TRUE(observedFragment.EqualsLiteral("3456789"));
+
+  i.FeedInput(NS_LITERAL_CSTRING("aqwert"));
+  EXPECT_TRUE(test == 4);
+  EXPECT_TRUE(observedFragment.EqualsLiteral("qwe"));
+
+  i.FinishInput();
+  EXPECT_TRUE(test == 6);
+}
+
+TEST(Tokenizer, IncrementalBuffering2)
+{
+  typedef TokenizerBase::Token Token;
+
+  int test = 0;
+  Token custom;
+  IncrementalTokenizer i([&](Token const& t, IncrementalTokenizer& i) -> nsresult
+  {
+    switch (++test) {
+      case 1: EXPECT_TRUE(t.Fragment().EqualsLiteral("01")); break;
+      case 2: EXPECT_TRUE(t.Fragment().EqualsLiteral("234567")); break;
+      case 3: EXPECT_TRUE(t.Fragment().EqualsLiteral("89")); break;
+      case 4: EXPECT_TRUE(t.Equals(custom)); break;
+      case 5: EXPECT_TRUE(t.Fragment().EqualsLiteral("qwert")); break;
+      case 6: EXPECT_TRUE(t.Equals(Token::EndOfFile())); break;
+    }
+    return NS_OK;
+  }, nullptr, nullptr, 3);
+
+  custom = i.AddCustomToken("aaa", Tokenizer::CASE_SENSITIVE);
+  // This externally unused token is added only to check the internal algorithm
+  // does work correctly as expected when there are two different length tokens.
+  Unused << i.AddCustomToken("bbbbb", Tokenizer::CASE_SENSITIVE);
+  i.SetTokenizingMode(Tokenizer::Mode::CUSTOM_ONLY);
+
+  i.FeedInput(NS_LITERAL_CSTRING("01234"));
+  EXPECT_TRUE(test == 0);
+  i.FeedInput(NS_LITERAL_CSTRING("5"));
+  EXPECT_TRUE(test == 1);
+  i.FeedInput(NS_LITERAL_CSTRING("6789aa"));
+  EXPECT_TRUE(test == 2);
+  i.FeedInput(NS_LITERAL_CSTRING("aqwert"));
+  EXPECT_TRUE(test == 4);
+  i.FinishInput();
+  EXPECT_TRUE(test == 6);
+}
diff --git a/xpcom/tests/gtest/TestUTF.cpp b/xpcom/tests/gtest/TestUTF.cpp
new file mode 100644
index 000000000..14dc03abe
--- /dev/null
+++ b/xpcom/tests/gtest/TestUTF.cpp
@@ -0,0 +1,191 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ArrayUtils.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "nsString.h"
+#include "nsStringBuffer.h"
+#include "nsReadableUtils.h"
+#include "UTFStrings.h"
+#include "nsUnicharUtils.h"
+#include "mozilla/HashFunctions.h"
+
+#include "gtest/gtest.h"
+
+using namespace mozilla;
+
+namespace TestUTF {
+
+TEST(UTF, Valid)
+{
+  for (unsigned int i = 0; i < ArrayLength(ValidStrings); ++i) {
+    nsDependentCString str8(ValidStrings[i].m8);
+    nsDependentString str16(ValidStrings[i].m16);
+
+    EXPECT_TRUE(NS_ConvertUTF16toUTF8(str16).Equals(str8));
+
+    EXPECT_TRUE(NS_ConvertUTF8toUTF16(str8).Equals(str16));
+
+    nsCString tmp8("string ");
+    AppendUTF16toUTF8(str16, tmp8);
+    EXPECT_TRUE(tmp8.Equals(NS_LITERAL_CSTRING("string ") + str8));
+
+    nsString tmp16(NS_LITERAL_STRING("string "));
+    AppendUTF8toUTF16(str8, tmp16);
+    EXPECT_TRUE(tmp16.Equals(NS_LITERAL_STRING("string ") + str16));
+
+    EXPECT_EQ(CompareUTF8toUTF16(str8, str16), 0);
+  }
+}
+
+TEST(UTF, Invalid16)
+{
+  for (unsigned int i = 0; i < ArrayLength(Invalid16Strings); ++i) {
+    nsDependentString str16(Invalid16Strings[i].m16);
+    nsDependentCString str8(Invalid16Strings[i].m8);
+
+    EXPECT_TRUE(NS_ConvertUTF16toUTF8(str16).Equals(str8));
+
+    nsCString tmp8("string ");
+    AppendUTF16toUTF8(str16, tmp8);
+    EXPECT_TRUE(tmp8.Equals(NS_LITERAL_CSTRING("string ") + str8));
+
+    EXPECT_EQ(CompareUTF8toUTF16(str8, str16), 0);
+  }
+}
+
+TEST(UTF, Invalid8)
+{
+  for (unsigned int i = 0; i < ArrayLength(Invalid8Strings); ++i) {
+    nsDependentString str16(Invalid8Strings[i].m16);
+    nsDependentCString str8(Invalid8Strings[i].m8);
+
+    EXPECT_TRUE(NS_ConvertUTF8toUTF16(str8).Equals(str16));
+
+    nsString tmp16(NS_LITERAL_STRING("string "));
+    AppendUTF8toUTF16(str8, tmp16);
+    EXPECT_TRUE(tmp16.Equals(NS_LITERAL_STRING("string ") + str16));
+
+    EXPECT_EQ(CompareUTF8toUTF16(str8, str16), 0);
+  }
+}
+
+TEST(UTF, Malformed8)
+{
+// Don't run this test in debug builds as that intentionally asserts.
+#ifndef DEBUG
+  for (unsigned int i = 0; i < ArrayLength(Malformed8Strings); ++i) {
+    nsDependentCString str8(Malformed8Strings[i]);
+
+    EXPECT_TRUE(NS_ConvertUTF8toUTF16(str8).IsEmpty());
+
+    nsString tmp16(NS_LITERAL_STRING("string"));
+    AppendUTF8toUTF16(str8, tmp16);
+    EXPECT_TRUE(tmp16.EqualsLiteral("string"));
+
+    EXPECT_NE(CompareUTF8toUTF16(str8, EmptyString()), 0);
+  }
+#endif
+}
+
+TEST(UTF, Hash16)
+{
+  for (unsigned int i = 0; i < ArrayLength(ValidStrings); ++i) {
+    nsDependentCString str8(ValidStrings[i].m8);
+    bool err;
+    EXPECT_EQ(HashString(ValidStrings[i].m16),
+              HashUTF8AsUTF16(str8.get(), str8.Length(), &err));
+    EXPECT_FALSE(err);
+  }
+
+  for (unsigned int i = 0; i < ArrayLength(Invalid8Strings); ++i) {
+    nsDependentCString str8(Invalid8Strings[i].m8);
+    bool err;
+    EXPECT_EQ(HashString(Invalid8Strings[i].m16),
+              HashUTF8AsUTF16(str8.get(), str8.Length(), &err));
+    EXPECT_FALSE(err);
+  }
+
+// Don't run this test in debug builds as that intentionally asserts.
+#ifndef DEBUG
+  for (unsigned int i = 0; i < ArrayLength(Malformed8Strings); ++i) {
+    nsDependentCString str8(Malformed8Strings[i]);
+    bool err;
+    EXPECT_EQ(HashUTF8AsUTF16(str8.get(), str8.Length(), &err), 0u);
+    EXPECT_TRUE(err);
+  }
+#endif
+}
+
+/**
+ * This tests the handling of a non-ascii character at various locations in a
+ * UTF-16 string that is being converted to UTF-8.
+ */
+void NonASCII16_helper(const size_t aStrSize)
+{
+  const size_t kTestSize = aStrSize;
+  const size_t kMaxASCII = 0x80;
+  const char16_t kUTF16Char = 0xC9;
+  const char kUTF8Surrogates[] = { char(0xC3), char(0x89) };
+
+  // Generate a string containing only ASCII characters.
+  nsString asciiString;
+  asciiString.SetLength(kTestSize);
+  nsCString asciiCString;
+  asciiCString.SetLength(kTestSize);
+
+  auto str_buff = asciiString.BeginWriting();
+  auto cstr_buff = asciiCString.BeginWriting();
+  for (size_t i = 0; i < kTestSize; i++) {
+    str_buff[i] = i % kMaxASCII;
+    cstr_buff[i] = i % kMaxASCII;
+  }
+
+  // Now go through and test conversion when exactly one character will
+  // result in a multibyte sequence.
+  for (size_t i = 0; i < kTestSize; i++) {
+    // Setup the UTF-16 string.
+    nsString unicodeString(asciiString);
+    auto buff = unicodeString.BeginWriting();
+    buff[i] = kUTF16Char;
+
+    // Do the conversion, make sure the length increased by 1.
+    nsCString dest;
+    AppendUTF16toUTF8(unicodeString, dest);
+    EXPECT_EQ(dest.Length(), unicodeString.Length() + 1);
+
+    // Build up the expected UTF-8 string.
+    nsCString expected;
+
+    // First add the leading ASCII chars.
+    expected.Append(asciiCString.BeginReading(), i);
+
+    // Now append the UTF-8 surrogate pair we expect the UTF-16 unicode char to
+    // be converted to.
+    for (auto& c : kUTF8Surrogates) {
+      expected.Append(c);
+    }
+
+    // And finish with the trailing ASCII chars.
+    expected.Append(asciiCString.BeginReading() + i + 1, kTestSize - i - 1);
+
+    EXPECT_STREQ(dest.BeginReading(), expected.BeginReading());
+  }
+}
+
+TEST(UTF, NonASCII16)
+{
+  // Test with various string sizes to catch any special casing.
+  NonASCII16_helper(1);
+  NonASCII16_helper(8);
+  NonASCII16_helper(16);
+  NonASCII16_helper(32);
+  NonASCII16_helper(512);
+}
+
+} // namespace TestUTF
diff --git a/xpcom/tests/gtest/TestXPIDLString.cpp b/xpcom/tests/gtest/TestXPIDLString.cpp
new file mode 100644
index 000000000..b26cc9aff
--- /dev/null
+++ b/xpcom/tests/gtest/TestXPIDLString.cpp
@@ -0,0 +1,24 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsString.h"
+#include "nsReadableUtils.h"
+#include "nsXPIDLString.h"
+#include "gtest/gtest.h"
+
+static void
+nsXPIDLStringTest_Value(char16_t** aResult)
+{
+  *aResult = ToNewUnicode(NS_LITERAL_STRING("Hello, World"));
+}
+
+TEST(XPIDLString, Main)
+{
+  nsXPIDLString s1;
+  nsXPIDLStringTest_Value(getter_Copies(s1));
+  EXPECT_TRUE(s1.EqualsLiteral("Hello, World"));
+}
+
diff --git a/xpcom/tests/gtest/UTFStrings.h b/xpcom/tests/gtest/UTFStrings.h
new file mode 100644
index 000000000..ec6bf15d3
--- /dev/null
+++ b/xpcom/tests/gtest/UTFStrings.h
@@ -0,0 +1,112 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef utfstrings_h__
+#define utfstrings_h__
+
+struct UTFStringsStringPair
+  {
+    char16_t m16[16];
+    char m8[16];
+  };
+
+static const UTFStringsStringPair ValidStrings[] =
+  {
+    { { 'a', 'b', 'c', 'd' },
+      { 'a', 'b', 'c', 'd' } },
+    { { '1', '2', '3', '4' },
+      { '1', '2', '3', '4' } },
+    { { 0x7F, 'A', 0x80, 'B', 0x101, 0x200 },
+      { 0x7F, 'A', char(0xC2), char(0x80), 'B', char(0xC4), char(0x81), char(0xC8), char(0x80) } },
+    { { 0x7FF, 0x800, 0x1000 },
+      { char(0xDF), char(0xBF), char(0xE0), char(0xA0), char(0x80), char(0xE1), char(0x80), char(0x80) } },
+    { { 0xD7FF, 0xE000, 0xF00F, 'A', 0xFFF0 },
+      { char(0xED), char(0x9F), char(0xBF), char(0xEE), char(0x80), char(0x80), char(0xEF), char(0x80), char(0x8F), 'A', char(0xEF), char(0xBF), char(0xB0) } },
+    { { 0xFFF7, 0xFFFC, 0xFFFD, 0xFFFD },
+      { char(0xEF), char(0xBF), char(0xB7), char(0xEF), char(0xBF), char(0xBC), char(0xEF), char(0xBF), char(0xBD), char(0xEF), char(0xBF), char(0xBD) } },
+    { { 0xD800, 0xDC00, 0xD800, 0xDCFF },
+      { char(0xF0), char(0x90), char(0x80), char(0x80), char(0xF0), char(0x90), char(0x83), char(0xBF) } },
+    { { 0xDBFF, 0xDFFF, 0xDBB7, 0xDCBA },
+      { char(0xF4), char(0x8F), char(0xBF), char(0xBF), char(0xF3), char(0xBD), char(0xB2), char(0xBA) } },
+    { { 0xFFFD, 0xFFFF },
+      { char(0xEF), char(0xBF), char(0xBD), char(0xEF), char(0xBF), char(0xBF) } },
+    { { 0xFFFD, 0xFFFE, 0xFFFF },
+      { char(0xEF), char(0xBF), char(0xBD), char(0xEF), char(0xBF), char(0xBE), char(0xEF), char(0xBF), char(0xBF) } },
+  };
+
+static const UTFStringsStringPair Invalid16Strings[] =
+  {
+    { { 'a', 'b', 0xD800 },
+      { 'a', 'b', char(0xEF), char(0xBF), char(0xBD) } },
+    { { 0xD8FF, 'b' },
+      { char(0xEF), char(0xBF), char(0xBD), 'b' } },
+    { { 0xD821 },
+      { char(0xEF), char(0xBF), char(0xBD) } },
+    { { 0xDC21 },
+      { char(0xEF), char(0xBF), char(0xBD) } },
+    { { 0xDC00, 0xD800, 'b' },
+      { char(0xEF), char(0xBF), char(0xBD), char(0xEF), char(0xBF), char(0xBD), 'b' } },
+    { { 'b', 0xDC00, 0xD800 },
+      { 'b', char(0xEF), char(0xBF), char(0xBD), char(0xEF), char(0xBF), char(0xBD) } },
+    { { 0xDC00, 0xD800 },
+      { char(0xEF), char(0xBF), char(0xBD), char(0xEF), char(0xBF), char(0xBD) } },
+    { { 0xDC00, 0xD800, 0xDC00, 0xD800 },
+      { char(0xEF), char(0xBF), char(0xBD), char(0xF0), char(0x90), char(0x80), char(0x80), char(0xEF), char(0xBF), char(0xBD) } },
+    { { 0xDC00, 0xD800, 0xD800, 0xDC00 },
+      { char(0xEF), char(0xBF), char(0xBD), char(0xEF), char(0xBF), char(0xBD), char(0xF0), char(0x90), char(0x80), char(0x80) } },
+  };
+
+static const UTFStringsStringPair Invalid8Strings[] =
+  {
+    { { 'a', 0xFFFD, 'b' },
+      { 'a', char(0xC0), char(0x80), 'b' } },
+    { { 0xFFFD, 0x80 },
+      { char(0xC1), char(0xBF), char(0xC2), char(0x80) } },
+    { { 0xFFFD },
+      { char(0xC1), char(0xBF) } },
+    { { 0xFFFD, 'x', 0x0800 },
+      { char(0xE0), char(0x80), char(0x80), 'x', char(0xE0), char(0xA0), char(0x80) } },
+    { { 0xFFFD, 'x', 0xFFFD },
+      { char(0xF0), char(0x80), char(0x80), char(0x80), 'x', char(0xF0), char(0x80), char(0x8F), char(0x80) } },
+    { { 0xFFFD, 0xFFFD },
+      { char(0xF4), char(0x90), char(0x80), char(0x80), char(0xF7), char(0xBF), char(0xBF), char(0xBF) } },
+    { { 0xFFFD, 'x', 0xD800, 0xDC00, 0xFFFD },
+      { char(0xF0), char(0x8F), char(0xBF), char(0xBF), 'x', char(0xF0), char(0x90), char(0x80), char(0x80), char(0xF0), char(0x8F), char(0xBF), char(0xBF) } },
+    { { 0xFFFD, 'x', 0xFFFD },
+      { char(0xF8), char(0x80), char(0x80), char(0x80), char(0x80), 'x', char(0xF8), char(0x88), char(0x80), char(0x80), char(0x80) } },
+    { { 0xFFFD, 0xFFFD },
+      { char(0xFB), char(0xBF), char(0xBF), char(0xBF), char(0xBF), char(0xFC), char(0xA0), char(0x80), char(0x80), char(0x80), char(0x80) } },
+    { { 0xFFFD, 0xFFFD },
+      { char(0xFC), char(0x80), char(0x80), char(0x80), char(0x80), char(0x80), char(0xFD), char(0xBF), char(0xBF), char(0xBF), char(0xBF), char(0xBF) } },
+  };
+
+// Don't use this array in debug builds as that intentionally asserts.
+#ifndef DEBUG
+static const char Malformed8Strings[][16] =
+  {
+    { char(0x80) },
+    { 'a', char(0xC8), 'c' },
+    { 'a', char(0xC0) },
+    { 'a', char(0xE8), 'c' },
+    { 'a', char(0xE8), char(0x80), 'c' },
+    { 'a', char(0xE8), char(0x80) },
+    { char(0xE8), 0x7F, char(0x80) },
+    { 'a', char(0xE8), char(0xE8), char(0x80) },
+    { 'a', char(0xF4) },
+    { 'a', char(0xF4), char(0x80), char(0x80), 'c', 'c' },
+    { 'a', char(0xF4), char(0x80), 'x', char(0x80) },
+    { char(0xF4), char(0x80), char(0x80), char(0x80), char(0x80) },
+    { 'a', char(0xFA), 'c' },
+    { 'a', char(0xFA), char(0x80), char(0x80), 0x7F, char(0x80), 'c' },
+    { 'a', char(0xFA), char(0x80), char(0x80), char(0x80), char(0x80), char(0x80), 'c' },
+    { 'a', char(0xFD) },
+    { 'a', char(0xFD), char(0x80), char(0x80), char(0x80), char(0x80), 'c' },
+    { 'a', char(0xFD), char(0x80), char(0x80), char(0x80), char(0x80), char(0x80), char(0x80) },
+    { 'a', char(0xFC), char(0x80), char(0x80), 0x40, char(0x80), char(0x80), 'c' },
+  };
+#endif
+
+#endif
diff --git a/xpcom/tests/gtest/moz.build b/xpcom/tests/gtest/moz.build
new file mode 100644
index 000000000..53836eaef
--- /dev/null
+++ b/xpcom/tests/gtest/moz.build
@@ -0,0 +1,77 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+UNIFIED_SOURCES += [
+    'Helpers.cpp',
+    'TestAtoms.cpp',
+    'TestAutoPtr.cpp',
+    'TestAutoRef.cpp',
+    'TestBase64.cpp',
+    'TestCallTemplates.cpp',
+    'TestCloneInputStream.cpp',
+    'TestCOMArray.cpp',
+    'TestCOMPtrEq.cpp',
+    'TestCRT.cpp',
+    'TestEncoding.cpp',
+    'TestEscapeURL.cpp',
+    'TestExpirationTracker.cpp',
+    'TestFile.cpp',
+    'TestID.cpp',
+    'TestNSPRLogModulesParser.cpp',
+    'TestObserverArray.cpp',
+    'TestObserverService.cpp',
+    'TestPipes.cpp',
+    'TestPLDHash.cpp',
+    'TestPriorityQueue.cpp',
+    'TestRacingServiceManager.cpp',
+    'TestSlicedInputStream.cpp',
+    'TestSnappyStreams.cpp',
+    'TestStateWatching.cpp',
+    'TestStorageStream.cpp',
+    'TestStrings.cpp',
+    'TestStringStream.cpp',
+    'TestSynchronization.cpp',
+    'TestTArray.cpp',
+    'TestTArray2.cpp',
+    'TestTextFormatter.cpp',
+    'TestThreadPool.cpp',
+    'TestThreadPoolListener.cpp',
+    'TestThreads.cpp',
+    'TestThreadUtils.cpp',
+    'TestTimers.cpp',
+    'TestTimeStamp.cpp',
+    'TestTokenizer.cpp',
+    'TestUTF.cpp',
+    'TestXPIDLString.cpp',
+]
+
+if CONFIG['MOZ_DEBUG'] and CONFIG['OS_ARCH'] not in ('WINNT') and CONFIG['OS_TARGET'] != 'Android':
+    # FIXME bug 523392: TestDeadlockDetector doesn't like Windows
+    # Bug 1054249: Doesn't work on Android
+    UNIFIED_SOURCES += [
+        'TestDeadlockDetector.cpp',
+        'TestDeadlockDetectorScalability.cpp',
+    ]
+
+if CONFIG['WRAP_STL_INCLUDES'] and not CONFIG['CLANG_CL']:
+    UNIFIED_SOURCES += [
+        'TestSTLWrappers.cpp',
+    ]
+
+# Compile TestAllocReplacement separately so Windows headers don't pollute
+# the global namespace for other files.
+SOURCES += [
+    'TestAllocReplacement.cpp',
+    'TestCOMPtr.cpp', # Redefines IFoo and IBar
+    'TestHashtables.cpp', # Redefines IFoo
+    'TestNsRefPtr.cpp', # Redefines Foo
+]
+
+LOCAL_INCLUDES += [
+    '../../base',
+]
+
+FINAL_LIBRARY = 'xul-gtest'
diff --git a/xpcom/tests/moz.build b/xpcom/tests/moz.build
new file mode 100644
index 000000000..b5fc138e7
--- /dev/null
+++ b/xpcom/tests/moz.build
@@ -0,0 +1,51 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+TEST_DIRS += [
+    'external',
+    'component',
+    'bug656331_component',
+    'component_no_aslr',
+    'gtest',
+]
+
+if CONFIG['OS_ARCH'] == 'WINNT':
+    TEST_DIRS += ['windows']
+
+EXPORTS.testing += [
+    'TestHarness.h',
+]
+
+SimplePrograms([
+    'TestArguments',
+    'TestBlockingProcess',
+    'TestPRIntN',
+    'TestQuickReturn',
+    'TestUnicodeArguments',
+])
+
+XPCSHELL_TESTS_MANIFESTS += ['unit/xpcshell.ini']
+
+if CONFIG['COMPILE_ENVIRONMENT']:
+    TEST_HARNESS_FILES.xpcshell.xpcom.tests.unit += [
+        '!/dist/bin/components/xpcomtest.xpt',
+    ]
+
+XPIDL_MODULE = 'xpcomtest'
+XPIDL_SOURCES += [
+    'NotXPCOMTest.idl',
+]
+
+# Don't add our test-only .xpt files to the normal manifests
+XPIDL_NO_MANIFEST = True
+
+LOCAL_INCLUDES += [
+    '../ds',
+]
+
+RESOURCE_FILES += [
+    'test.properties',
+]
diff --git a/xpcom/tests/resources.h b/xpcom/tests/resources.h
new file mode 100644
index 000000000..4deea759f
--- /dev/null
+++ b/xpcom/tests/resources.h
@@ -0,0 +1,19 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef resources_h___
+#define resources_h___
+
+#define TIMER_1SECOND             40000
+#define TIMER_5SECOND             40001
+#define TIMER_10SECOND            40002
+
+#define TIMER_1REPEAT             40003
+#define TIMER_5REPEAT             40004
+#define TIMER_10REPEAT            40005
+
+#define TIMER_CANCEL              40006
+#define TIMER_EXIT                40010
+
+#endif /* resources_h___ */
diff --git a/xpcom/tests/test.properties b/xpcom/tests/test.properties
new file mode 100644
index 000000000..19cae9702
--- /dev/null
+++ b/xpcom/tests/test.properties
@@ -0,0 +1,14 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+1=1
+ 2=2
+3 =3
+ 4 =4
+5=5
+6= 6
+7=7 
+8= 8 
+# this is a comment
+9=this is the first part of a continued line \
+ and here is the 2nd part
diff --git a/xpcom/tests/unit/bug725015.manifest b/xpcom/tests/unit/bug725015.manifest
new file mode 100644
index 000000000..2f432f0b2
--- /dev/null
+++ b/xpcom/tests/unit/bug725015.manifest
@@ -0,0 +1,3 @@
+category bug725015-test-category bug725015-category-entry @bug725015.test.contract

+component {05070380-6e6e-42ba-aaa5-3289fc55ca5a} dummyfile.js

+contract @bug725015.test.contract {05070380-6e6e-42ba-aaa5-3289fc55ca5a}

diff --git a/xpcom/tests/unit/compmgr_warnings.manifest b/xpcom/tests/unit/compmgr_warnings.manifest
new file mode 100644
index 000000000..6b60990db
--- /dev/null
+++ b/xpcom/tests/unit/compmgr_warnings.manifest
@@ -0,0 +1,9 @@
+# The following line is malformed (mismatched braces)
+component {94b346d7-0cde-4e6e-b819-95d6f200bbf6 MyComponent.js
+
+component 94b346d7-0cde-4e6e-b819-95d6f200bbf7 MyComponent.js
+# The following line re-registers an existing CID
+component {94b346d7-0cde-4e6e-b819-95d6f200bbf7} MyOtherComponent.js
+
+# The following line maps a contractID to a non-existent CID
+contract @testing/foo {0c07730f-f875-436b-8deb-90c4251920ec}
diff --git a/xpcom/tests/unit/data/SmallApp.app/Contents/Info.plist b/xpcom/tests/unit/data/SmallApp.app/Contents/Info.plist
new file mode 100644
index 000000000..8388fa2a5
--- /dev/null
+++ b/xpcom/tests/unit/data/SmallApp.app/Contents/Info.plist
@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>CFBundleDevelopmentRegion</key>
+	<string>English</string>
+	<key>CFBundleExecutable</key>
+	<string>SmallApp</string>
+	<key>CFBundleIdentifier</key>
+	<string>com.yourcompany.SmallApp</string>
+	<key>CFBundleInfoDictionaryVersion</key>
+	<string>6.0</string>
+	<key>CFBundleName</key>
+	<string>SmallApp</string>
+	<key>CFBundlePackageType</key>
+	<string>APPL</string>
+	<key>CFBundleSignature</key>
+	<string>????</string>
+	<key>CFBundleVersion</key>
+	<string>1.0</string>
+	<key>NSMainNibFile</key>
+	<string>MainMenu</string>
+	<key>NSPrincipalClass</key>
+	<string>NSApplication</string>
+</dict>
+</plist>
diff --git a/xpcom/tests/unit/data/SmallApp.app/Contents/MacOS/SmallApp b/xpcom/tests/unit/data/SmallApp.app/Contents/MacOS/SmallApp
new file mode 100755
index 000000000..c821003d3
--- /dev/null
+++ b/xpcom/tests/unit/data/SmallApp.app/Contents/MacOS/SmallApp
diff --git a/xpcom/tests/unit/data/SmallApp.app/Contents/PkgInfo b/xpcom/tests/unit/data/SmallApp.app/Contents/PkgInfo
new file mode 100644
index 000000000..bd04210fb
--- /dev/null
+++ b/xpcom/tests/unit/data/SmallApp.app/Contents/PkgInfo
@@ -0,0 +1 @@
+APPL????
\ No newline at end of file
diff --git a/xpcom/tests/unit/data/SmallApp.app/Contents/Resources/English.lproj/InfoPlist.strings b/xpcom/tests/unit/data/SmallApp.app/Contents/Resources/English.lproj/InfoPlist.strings
new file mode 100644
index 000000000..5e45963c3
--- /dev/null
+++ b/xpcom/tests/unit/data/SmallApp.app/Contents/Resources/English.lproj/InfoPlist.strings
diff --git a/xpcom/tests/unit/data/SmallApp.app/Contents/Resources/English.lproj/MainMenu.nib/designable.nib b/xpcom/tests/unit/data/SmallApp.app/Contents/Resources/English.lproj/MainMenu.nib/designable.nib
new file mode 100644
index 000000000..59f8803c5
--- /dev/null
+++ b/xpcom/tests/unit/data/SmallApp.app/Contents/Resources/English.lproj/MainMenu.nib/designable.nib
@@ -0,0 +1,343 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<archive type="com.apple.InterfaceBuilder3.Cocoa.XIB" version="7.02">
+	<data>
+		<int key="IBDocument.SystemTarget">0</int>
+		<string key="IBDocument.SystemVersion">9E17</string>
+		<string key="IBDocument.InterfaceBuilderVersion">644</string>
+		<string key="IBDocument.AppKitVersion">949.33</string>
+		<string key="IBDocument.HIToolboxVersion">352.00</string>
+		<object class="NSMutableArray" key="IBDocument.EditedObjectIDs">
+			<bool key="EncodedWithXMLCoder">YES</bool>
+			<integer value="29"/>
+		</object>
+		<object class="NSArray" key="IBDocument.PluginDependencies">
+			<bool key="EncodedWithXMLCoder">YES</bool>
+			<string>com.apple.InterfaceBuilderKit</string>
+			<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
+		</object>
+		<object class="NSMutableArray" key="IBDocument.RootObjects" id="1048">
+			<bool key="EncodedWithXMLCoder">YES</bool>
+			<object class="NSCustomObject" id="1021">
+				<string key="NSClassName">NSApplication</string>
+			</object>
+			<object class="NSCustomObject" id="1014">
+				<string key="NSClassName">FirstResponder</string>
+			</object>
+			<object class="NSCustomObject" id="1050">
+				<string key="NSClassName">NSApplication</string>
+			</object>
+			<object class="NSMenu" id="649796088">
+				<string key="NSTitle">AMainMenu</string>
+				<object class="NSMutableArray" key="NSMenuItems">
+					<bool key="EncodedWithXMLCoder">YES</bool>
+					<object class="NSMenuItem" id="694149608">
+						<reference key="NSMenu" ref="649796088"/>
+						<string key="NSTitle">NewApplication</string>
+						<string key="NSKeyEquiv"/>
+						<int key="NSKeyEquivModMask">1048576</int>
+						<int key="NSMnemonicLoc">2147483647</int>
+						<object class="NSCustomResource" key="NSOnImage" id="35465992">
+							<string key="NSClassName">NSImage</string>
+							<string key="NSResourceName">NSMenuCheckmark</string>
+						</object>
+						<object class="NSCustomResource" key="NSMixedImage" id="591987212">
+							<string key="NSClassName">NSImage</string>
+							<string key="NSResourceName">NSMenuMixedState</string>
+						</object>
+						<string key="NSAction">submenuAction:</string>
+						<object class="NSMenu" key="NSSubmenu" id="110575045">
+							<string key="NSTitle">NewApplication</string>
+							<object class="NSMutableArray" key="NSMenuItems">
+								<bool key="EncodedWithXMLCoder">YES</bool>
+								<object class="NSMenuItem" id="632727374">
+									<reference key="NSMenu" ref="110575045"/>
+									<string key="NSTitle">Quit NewApplication</string>
+									<string key="NSKeyEquiv">q</string>
+									<int key="NSKeyEquivModMask">1048576</int>
+									<int key="NSMnemonicLoc">2147483647</int>
+									<reference key="NSOnImage" ref="35465992"/>
+									<reference key="NSMixedImage" ref="591987212"/>
+								</object>
+							</object>
+							<string key="NSName">_NSAppleMenu</string>
+						</object>
+					</object>
+					<object class="NSMenuItem" id="379814623">
+						<reference key="NSMenu" ref="649796088"/>
+						<string key="NSTitle">File</string>
+						<string key="NSKeyEquiv"/>
+						<int key="NSKeyEquivModMask">1048576</int>
+						<int key="NSMnemonicLoc">2147483647</int>
+						<reference key="NSOnImage" ref="35465992"/>
+						<reference key="NSMixedImage" ref="591987212"/>
+					</object>
+					<object class="NSMenuItem" id="952259628">
+						<reference key="NSMenu" ref="649796088"/>
+						<string key="NSTitle">Edit</string>
+						<string key="NSKeyEquiv"/>
+						<int key="NSKeyEquivModMask">1048576</int>
+						<int key="NSMnemonicLoc">2147483647</int>
+						<reference key="NSOnImage" ref="35465992"/>
+						<reference key="NSMixedImage" ref="591987212"/>
+					</object>
+					<object class="NSMenuItem" id="626404410">
+						<reference key="NSMenu" ref="649796088"/>
+						<string key="NSTitle">Format</string>
+						<string key="NSKeyEquiv"/>
+						<int key="NSKeyEquivModMask">1048576</int>
+						<int key="NSMnemonicLoc">2147483647</int>
+						<reference key="NSOnImage" ref="35465992"/>
+						<reference key="NSMixedImage" ref="591987212"/>
+					</object>
+					<object class="NSMenuItem" id="586577488">
+						<reference key="NSMenu" ref="649796088"/>
+						<string key="NSTitle">View</string>
+						<string key="NSKeyEquiv"/>
+						<int key="NSKeyEquivModMask">1048576</int>
+						<int key="NSMnemonicLoc">2147483647</int>
+						<reference key="NSOnImage" ref="35465992"/>
+						<reference key="NSMixedImage" ref="591987212"/>
+					</object>
+					<object class="NSMenuItem" id="713487014">
+						<reference key="NSMenu" ref="649796088"/>
+						<string key="NSTitle">Window</string>
+						<string key="NSKeyEquiv"/>
+						<int key="NSKeyEquivModMask">1048576</int>
+						<int key="NSMnemonicLoc">2147483647</int>
+						<reference key="NSOnImage" ref="35465992"/>
+						<reference key="NSMixedImage" ref="591987212"/>
+					</object>
+					<object class="NSMenuItem" id="391199113">
+						<reference key="NSMenu" ref="649796088"/>
+						<string key="NSTitle">Help</string>
+						<string key="NSKeyEquiv"/>
+						<int key="NSKeyEquivModMask">1048576</int>
+						<int key="NSMnemonicLoc">2147483647</int>
+						<reference key="NSOnImage" ref="35465992"/>
+						<reference key="NSMixedImage" ref="591987212"/>
+					</object>
+				</object>
+				<string key="NSName">_NSMainMenu</string>
+			</object>
+		</object>
+		<object class="IBObjectContainer" key="IBDocument.Objects">
+			<object class="NSMutableArray" key="connectionRecords">
+				<bool key="EncodedWithXMLCoder">YES</bool>
+				<object class="IBConnectionRecord">
+					<object class="IBActionConnection" key="connection">
+						<string key="label">terminate:</string>
+						<reference key="source" ref="1014"/>
+						<reference key="destination" ref="632727374"/>
+					</object>
+					<int key="connectionID">369</int>
+				</object>
+			</object>
+			<object class="IBMutableOrderedSet" key="objectRecords">
+				<object class="NSArray" key="orderedObjects">
+					<bool key="EncodedWithXMLCoder">YES</bool>
+					<object class="IBObjectRecord">
+						<int key="objectID">0</int>
+						<object class="NSArray" key="object" id="1049">
+							<bool key="EncodedWithXMLCoder">YES</bool>
+						</object>
+						<reference key="children" ref="1048"/>
+						<nil key="parent"/>
+					</object>
+					<object class="IBObjectRecord">
+						<int key="objectID">-2</int>
+						<reference key="object" ref="1021"/>
+						<reference key="parent" ref="1049"/>
+						<string type="base64-UTF8" key="objectName">RmlsZSdzIE93bmVyA</string>
+					</object>
+					<object class="IBObjectRecord">
+						<int key="objectID">-1</int>
+						<reference key="object" ref="1014"/>
+						<reference key="parent" ref="1049"/>
+						<string key="objectName">First Responder</string>
+					</object>
+					<object class="IBObjectRecord">
+						<int key="objectID">-3</int>
+						<reference key="object" ref="1050"/>
+						<reference key="parent" ref="1049"/>
+						<string key="objectName">Application</string>
+					</object>
+					<object class="IBObjectRecord">
+						<int key="objectID">29</int>
+						<reference key="object" ref="649796088"/>
+						<object class="NSMutableArray" key="children">
+							<bool key="EncodedWithXMLCoder">YES</bool>
+							<reference ref="713487014"/>
+							<reference ref="694149608"/>
+							<reference ref="391199113"/>
+							<reference ref="952259628"/>
+							<reference ref="379814623"/>
+							<reference ref="586577488"/>
+							<reference ref="626404410"/>
+						</object>
+						<reference key="parent" ref="1049"/>
+						<string key="objectName">MainMenu</string>
+					</object>
+					<object class="IBObjectRecord">
+						<int key="objectID">19</int>
+						<reference key="object" ref="713487014"/>
+						<object class="NSMutableArray" key="children">
+							<bool key="EncodedWithXMLCoder">YES</bool>
+						</object>
+						<reference key="parent" ref="649796088"/>
+					</object>
+					<object class="IBObjectRecord">
+						<int key="objectID">56</int>
+						<reference key="object" ref="694149608"/>
+						<object class="NSMutableArray" key="children">
+							<bool key="EncodedWithXMLCoder">YES</bool>
+							<reference ref="110575045"/>
+						</object>
+						<reference key="parent" ref="649796088"/>
+					</object>
+					<object class="IBObjectRecord">
+						<int key="objectID">103</int>
+						<reference key="object" ref="391199113"/>
+						<object class="NSMutableArray" key="children">
+							<bool key="EncodedWithXMLCoder">YES</bool>
+						</object>
+						<reference key="parent" ref="649796088"/>
+						<string key="objectName">1</string>
+					</object>
+					<object class="IBObjectRecord">
+						<int key="objectID">217</int>
+						<reference key="object" ref="952259628"/>
+						<object class="NSMutableArray" key="children">
+							<bool key="EncodedWithXMLCoder">YES</bool>
+						</object>
+						<reference key="parent" ref="649796088"/>
+					</object>
+					<object class="IBObjectRecord">
+						<int key="objectID">83</int>
+						<reference key="object" ref="379814623"/>
+						<object class="NSMutableArray" key="children">
+							<bool key="EncodedWithXMLCoder">YES</bool>
+						</object>
+						<reference key="parent" ref="649796088"/>
+					</object>
+					<object class="IBObjectRecord">
+						<int key="objectID">57</int>
+						<reference key="object" ref="110575045"/>
+						<object class="NSMutableArray" key="children">
+							<bool key="EncodedWithXMLCoder">YES</bool>
+							<reference ref="632727374"/>
+						</object>
+						<reference key="parent" ref="694149608"/>
+					</object>
+					<object class="IBObjectRecord">
+						<int key="objectID">136</int>
+						<reference key="object" ref="632727374"/>
+						<reference key="parent" ref="110575045"/>
+						<string key="objectName">1111</string>
+					</object>
+					<object class="IBObjectRecord">
+						<int key="objectID">295</int>
+						<reference key="object" ref="586577488"/>
+						<object class="NSMutableArray" key="children">
+							<bool key="EncodedWithXMLCoder">YES</bool>
+						</object>
+						<reference key="parent" ref="649796088"/>
+					</object>
+					<object class="IBObjectRecord">
+						<int key="objectID">299</int>
+						<reference key="object" ref="626404410"/>
+						<object class="NSMutableArray" key="children">
+							<bool key="EncodedWithXMLCoder">YES</bool>
+						</object>
+						<reference key="parent" ref="649796088"/>
+					</object>
+				</object>
+			</object>
+			<object class="NSMutableDictionary" key="flattenedProperties">
+				<bool key="EncodedWithXMLCoder">YES</bool>
+				<object class="NSMutableArray" key="dict.sortedKeys">
+					<bool key="EncodedWithXMLCoder">YES</bool>
+					<string>-1.IBPluginDependency</string>
+					<string>-2.IBPluginDependency</string>
+					<string>-3.IBPluginDependency</string>
+					<string>103.IBPluginDependency</string>
+					<string>103.ImportedFromIB2</string>
+					<string>136.IBPluginDependency</string>
+					<string>136.ImportedFromIB2</string>
+					<string>19.IBPluginDependency</string>
+					<string>19.ImportedFromIB2</string>
+					<string>217.IBPluginDependency</string>
+					<string>217.ImportedFromIB2</string>
+					<string>29.IBEditorWindowLastContentRect</string>
+					<string>29.IBPluginDependency</string>
+					<string>29.ImportedFromIB2</string>
+					<string>29.WindowOrigin</string>
+					<string>29.editorWindowContentRectSynchronizationRect</string>
+					<string>295.IBPluginDependency</string>
+					<string>299.IBPluginDependency</string>
+					<string>56.IBPluginDependency</string>
+					<string>56.ImportedFromIB2</string>
+					<string>57.IBEditorWindowLastContentRect</string>
+					<string>57.IBPluginDependency</string>
+					<string>57.ImportedFromIB2</string>
+					<string>57.editorWindowContentRectSynchronizationRect</string>
+					<string>83.IBPluginDependency</string>
+					<string>83.ImportedFromIB2</string>
+				</object>
+				<object class="NSMutableArray" key="dict.values">
+					<bool key="EncodedWithXMLCoder">YES</bool>
+					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
+					<string>com.apple.InterfaceBuilderKit</string>
+					<string>com.apple.InterfaceBuilderKit</string>
+					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
+					<integer value="1" id="9"/>
+					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
+					<reference ref="9"/>
+					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
+					<reference ref="9"/>
+					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
+					<reference ref="9"/>
+					<string>{{0, 975}, {478, 20}}</string>
+					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
+					<reference ref="9"/>
+					<string>{74, 862}</string>
+					<string>{{6, 978}, {478, 20}}</string>
+					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
+					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
+					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
+					<reference ref="9"/>
+					<string>{{12, 952}, {218, 23}}</string>
+					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
+					<reference ref="9"/>
+					<string>{{23, 794}, {245, 183}}</string>
+					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
+					<reference ref="9"/>
+				</object>
+			</object>
+			<object class="NSMutableDictionary" key="unlocalizedProperties">
+				<bool key="EncodedWithXMLCoder">YES</bool>
+				<object class="NSArray" key="dict.sortedKeys">
+					<bool key="EncodedWithXMLCoder">YES</bool>
+				</object>
+				<object class="NSMutableArray" key="dict.values">
+					<bool key="EncodedWithXMLCoder">YES</bool>
+				</object>
+			</object>
+			<nil key="activeLocalization"/>
+			<object class="NSMutableDictionary" key="localizations">
+				<bool key="EncodedWithXMLCoder">YES</bool>
+				<object class="NSArray" key="dict.sortedKeys">
+					<bool key="EncodedWithXMLCoder">YES</bool>
+				</object>
+				<object class="NSMutableArray" key="dict.values">
+					<bool key="EncodedWithXMLCoder">YES</bool>
+				</object>
+			</object>
+			<nil key="sourceID"/>
+			<int key="maxID">374</int>
+		</object>
+		<object class="IBClassDescriber" key="IBDocument.Classes"/>
+		<int key="IBDocument.localizationMode">0</int>
+		<string key="IBDocument.LastKnownRelativeProjectPath">../SmallApp.xcodeproj</string>
+		<int key="IBDocument.defaultPropertyAccessControl">3</int>
+	</data>
+</archive>
diff --git a/xpcom/tests/unit/data/SmallApp.app/Contents/Resources/English.lproj/MainMenu.nib/keyedobjects.nib b/xpcom/tests/unit/data/SmallApp.app/Contents/Resources/English.lproj/MainMenu.nib/keyedobjects.nib
new file mode 100644
index 000000000..bb27d4a5d
--- /dev/null
+++ b/xpcom/tests/unit/data/SmallApp.app/Contents/Resources/English.lproj/MainMenu.nib/keyedobjects.nib
diff --git a/xpcom/tests/unit/data/bug121341-2.properties b/xpcom/tests/unit/data/bug121341-2.properties
new file mode 100644
index 000000000..f7885e4fc
--- /dev/null
+++ b/xpcom/tests/unit/data/bug121341-2.properties
@@ -0,0 +1,9 @@
+# this file contains invalid UTF-8 sequence
+# no property should be loaded
+
+1 = test
+
+# property with invalid UTF-8 sequence (0xa0)
+2 = a b
+
+3 = test2
diff --git a/xpcom/tests/unit/data/bug121341.properties b/xpcom/tests/unit/data/bug121341.properties
new file mode 100644
index 000000000..b45fc9698
--- /dev/null
+++ b/xpcom/tests/unit/data/bug121341.properties
@@ -0,0 +1,68 @@
+# simple check
+1=abc
+# test whitespace trimming in key and value
+  2	=   xy	
+# test parsing of escaped values
+3 = \u1234\t\r\n\uAB\
+\u1\n
+# test multiline properties
+4 = this is \
+multiline property
+5 = this is \
+	   another multiline property
+# property with DOS EOL

+6 = test\u0036

+# test multiline property with with DOS EOL
+7 = yet another multi\

+    line propery

+# trimming should not trim escaped whitespaces
+8 =	\ttest5\u0020	
+# another variant of #8
+9 =     \ test6\t	    
+# test UTF-8 encoded property/value
+10aሴb = c췯d
+# next property should test unicode escaping at the boundary of parsing buffer
+# buffer size is expected to be 4096 so add comments to get to this offset
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+################################################################################
+###############################################################################
+11 = \uABCD
diff --git a/xpcom/tests/unit/data/child_process_directive_service.js b/xpcom/tests/unit/data/child_process_directive_service.js
new file mode 100644
index 000000000..9bc1c3206
--- /dev/null
+++ b/xpcom/tests/unit/data/child_process_directive_service.js
@@ -0,0 +1,21 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+Components.utils.import("resource:///modules/XPCOMUtils.jsm");
+
+function TestProcessDirective() {}
+TestProcessDirective.prototype = {
+
+  /* Boilerplate */
+  QueryInterface: XPCOMUtils.generateQI([Components.interfaces.nsISupportsString]),
+  contractID: "@mozilla.org/xpcom/tests/ChildProcessDirectiveTest;1",
+  classID: Components.ID("{4bd1ba60-45c4-11e4-916c-0800200c9a66}"),
+
+  type: Components.interfaces.nsISupportsString.TYPE_STRING,
+  data: "child process",
+  toString: function() {
+    return this.data;
+  }
+};
+
+this.NSGetFactory = XPCOMUtils.generateNSGetFactory([TestProcessDirective]);
diff --git a/xpcom/tests/unit/data/iniparser01-utf16leBOM.ini b/xpcom/tests/unit/data/iniparser01-utf16leBOM.ini
new file mode 100644
index 000000000..46b134b19
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser01-utf16leBOM.ini
@@ -0,0 +1 @@
+ÿþ
\ No newline at end of file
diff --git a/xpcom/tests/unit/data/iniparser01-utf8BOM.ini b/xpcom/tests/unit/data/iniparser01-utf8BOM.ini
new file mode 100644
index 000000000..5f282702b
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser01-utf8BOM.ini
@@ -0,0 +1 @@
+
\ No newline at end of file
diff --git a/xpcom/tests/unit/data/iniparser01.ini b/xpcom/tests/unit/data/iniparser01.ini
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser01.ini
diff --git a/xpcom/tests/unit/data/iniparser02-utf16leBOM.ini b/xpcom/tests/unit/data/iniparser02-utf16leBOM.ini
new file mode 100644
index 000000000..49cc8ef0e
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser02-utf16leBOM.ini
diff --git a/xpcom/tests/unit/data/iniparser02-utf8BOM.ini b/xpcom/tests/unit/data/iniparser02-utf8BOM.ini
new file mode 100644
index 000000000..e02abfc9b
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser02-utf8BOM.ini
@@ -0,0 +1 @@
+
diff --git a/xpcom/tests/unit/data/iniparser02.ini b/xpcom/tests/unit/data/iniparser02.ini
new file mode 100644
index 000000000..d3f5a12fa
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser02.ini
@@ -0,0 +1 @@
+

diff --git a/xpcom/tests/unit/data/iniparser03-utf16leBOM.ini b/xpcom/tests/unit/data/iniparser03-utf16leBOM.ini
new file mode 100644
index 000000000..05255100a
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser03-utf16leBOM.ini
diff --git a/xpcom/tests/unit/data/iniparser03-utf8BOM.ini b/xpcom/tests/unit/data/iniparser03-utf8BOM.ini
new file mode 100644
index 000000000..b76e44e19
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser03-utf8BOM.ini
@@ -0,0 +1 @@
+[]
diff --git a/xpcom/tests/unit/data/iniparser03.ini b/xpcom/tests/unit/data/iniparser03.ini
new file mode 100644
index 000000000..60b074253
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser03.ini
@@ -0,0 +1 @@
+[]

diff --git a/xpcom/tests/unit/data/iniparser04-utf16leBOM.ini b/xpcom/tests/unit/data/iniparser04-utf16leBOM.ini
new file mode 100644
index 000000000..e95d97113
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser04-utf16leBOM.ini
diff --git a/xpcom/tests/unit/data/iniparser04-utf8BOM.ini b/xpcom/tests/unit/data/iniparser04-utf8BOM.ini
new file mode 100644
index 000000000..47ef32c0a
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser04-utf8BOM.ini
@@ -0,0 +1 @@
+[section1]
diff --git a/xpcom/tests/unit/data/iniparser04.ini b/xpcom/tests/unit/data/iniparser04.ini
new file mode 100644
index 000000000..23a50d155
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser04.ini
@@ -0,0 +1 @@
+[section1]

diff --git a/xpcom/tests/unit/data/iniparser05-utf16leBOM.ini b/xpcom/tests/unit/data/iniparser05-utf16leBOM.ini
new file mode 100644
index 000000000..a49491816
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser05-utf16leBOM.ini
diff --git a/xpcom/tests/unit/data/iniparser05-utf8BOM.ini b/xpcom/tests/unit/data/iniparser05-utf8BOM.ini
new file mode 100644
index 000000000..eb33b5ccf
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser05-utf8BOM.ini
@@ -0,0 +1 @@
+[section1]junk
diff --git a/xpcom/tests/unit/data/iniparser05.ini b/xpcom/tests/unit/data/iniparser05.ini
new file mode 100644
index 000000000..ade137337
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser05.ini
@@ -0,0 +1 @@
+[section1]junk

diff --git a/xpcom/tests/unit/data/iniparser06-utf16leBOM.ini b/xpcom/tests/unit/data/iniparser06-utf16leBOM.ini
new file mode 100644
index 000000000..e9023ac7c
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser06-utf16leBOM.ini
diff --git a/xpcom/tests/unit/data/iniparser06-utf8BOM.ini b/xpcom/tests/unit/data/iniparser06-utf8BOM.ini
new file mode 100644
index 000000000..073d841cf
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser06-utf8BOM.ini
@@ -0,0 +1,2 @@
+[section1]
+
diff --git a/xpcom/tests/unit/data/iniparser06.ini b/xpcom/tests/unit/data/iniparser06.ini
new file mode 100644
index 000000000..c24821e6e
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser06.ini
@@ -0,0 +1,2 @@
+[section1]

+

diff --git a/xpcom/tests/unit/data/iniparser07-utf16leBOM.ini b/xpcom/tests/unit/data/iniparser07-utf16leBOM.ini
new file mode 100644
index 000000000..d1c167e6e
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser07-utf16leBOM.ini
diff --git a/xpcom/tests/unit/data/iniparser07-utf8BOM.ini b/xpcom/tests/unit/data/iniparser07-utf8BOM.ini
new file mode 100644
index 000000000..38176d944
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser07-utf8BOM.ini
@@ -0,0 +1,2 @@
+[section1]
+name1
diff --git a/xpcom/tests/unit/data/iniparser07.ini b/xpcom/tests/unit/data/iniparser07.ini
new file mode 100644
index 000000000..49816873b
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser07.ini
@@ -0,0 +1,2 @@
+[section1]

+name1

diff --git a/xpcom/tests/unit/data/iniparser08-utf16leBOM.ini b/xpcom/tests/unit/data/iniparser08-utf16leBOM.ini
new file mode 100644
index 000000000..e450566a0
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser08-utf16leBOM.ini
diff --git a/xpcom/tests/unit/data/iniparser08-utf8BOM.ini b/xpcom/tests/unit/data/iniparser08-utf8BOM.ini
new file mode 100644
index 000000000..5fa7d2495
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser08-utf8BOM.ini
@@ -0,0 +1,2 @@
+[section1]
+name1=
diff --git a/xpcom/tests/unit/data/iniparser08.ini b/xpcom/tests/unit/data/iniparser08.ini
new file mode 100644
index 000000000..cfa15c9ff
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser08.ini
@@ -0,0 +1,2 @@
+[section1]

+name1=

diff --git a/xpcom/tests/unit/data/iniparser09-utf16leBOM.ini b/xpcom/tests/unit/data/iniparser09-utf16leBOM.ini
new file mode 100644
index 000000000..ef1da39e2
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser09-utf16leBOM.ini
diff --git a/xpcom/tests/unit/data/iniparser09-utf8BOM.ini b/xpcom/tests/unit/data/iniparser09-utf8BOM.ini
new file mode 100644
index 000000000..e3edce4d4
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser09-utf8BOM.ini
@@ -0,0 +1,2 @@
+[section1]
+name1=value1
diff --git a/xpcom/tests/unit/data/iniparser09.ini b/xpcom/tests/unit/data/iniparser09.ini
new file mode 100644
index 000000000..1c87762ba
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser09.ini
@@ -0,0 +1,2 @@
+[section1]

+name1=value1

diff --git a/xpcom/tests/unit/data/iniparser10-utf16leBOM.ini b/xpcom/tests/unit/data/iniparser10-utf16leBOM.ini
new file mode 100644
index 000000000..e5e70b661
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser10-utf16leBOM.ini
diff --git a/xpcom/tests/unit/data/iniparser10-utf8BOM.ini b/xpcom/tests/unit/data/iniparser10-utf8BOM.ini
new file mode 100644
index 000000000..bda15fcc7
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser10-utf8BOM.ini
@@ -0,0 +1,3 @@
+
+[section1]
+name1=value1
diff --git a/xpcom/tests/unit/data/iniparser10.ini b/xpcom/tests/unit/data/iniparser10.ini
new file mode 100644
index 000000000..037fd7930
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser10.ini
@@ -0,0 +1,3 @@
+

+[section1]

+name1=value1

diff --git a/xpcom/tests/unit/data/iniparser11-utf16leBOM.ini b/xpcom/tests/unit/data/iniparser11-utf16leBOM.ini
new file mode 100644
index 000000000..932d4004b
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser11-utf16leBOM.ini
diff --git a/xpcom/tests/unit/data/iniparser11-utf8BOM.ini b/xpcom/tests/unit/data/iniparser11-utf8BOM.ini
new file mode 100644
index 000000000..78caafaba
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser11-utf8BOM.ini
@@ -0,0 +1,3 @@
+# comment
+[section1]
+name1=value1
diff --git a/xpcom/tests/unit/data/iniparser11.ini b/xpcom/tests/unit/data/iniparser11.ini
new file mode 100644
index 000000000..f8d573a28
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser11.ini
@@ -0,0 +1,3 @@
+# comment

+[section1]

+name1=value1

diff --git a/xpcom/tests/unit/data/iniparser12-utf16leBOM.ini b/xpcom/tests/unit/data/iniparser12-utf16leBOM.ini
new file mode 100644
index 000000000..8a2912722
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser12-utf16leBOM.ini
diff --git a/xpcom/tests/unit/data/iniparser12-utf8BOM.ini b/xpcom/tests/unit/data/iniparser12-utf8BOM.ini
new file mode 100644
index 000000000..09ca62779
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser12-utf8BOM.ini
@@ -0,0 +1,3 @@
+[section1]
+# [sectionBAD]
+name1=value1
diff --git a/xpcom/tests/unit/data/iniparser12.ini b/xpcom/tests/unit/data/iniparser12.ini
new file mode 100644
index 000000000..2727940c0
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser12.ini
@@ -0,0 +1,3 @@
+[section1]

+# [sectionBAD]

+name1=value1

diff --git a/xpcom/tests/unit/data/iniparser13-utf16leBOM.ini b/xpcom/tests/unit/data/iniparser13-utf16leBOM.ini
new file mode 100644
index 000000000..ebd9a51d3
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser13-utf16leBOM.ini
diff --git a/xpcom/tests/unit/data/iniparser13-utf8BOM.ini b/xpcom/tests/unit/data/iniparser13-utf8BOM.ini
new file mode 100644
index 000000000..8c9499b66
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser13-utf8BOM.ini
@@ -0,0 +1,3 @@
+[section1]
+name1=value1
+# nameBAD=valueBAD
diff --git a/xpcom/tests/unit/data/iniparser13.ini b/xpcom/tests/unit/data/iniparser13.ini
new file mode 100644
index 000000000..21d40b140
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser13.ini
@@ -0,0 +1,3 @@
+[section1]

+name1=value1

+# nameBAD=valueBAD

diff --git a/xpcom/tests/unit/data/iniparser14-utf16leBOM.ini b/xpcom/tests/unit/data/iniparser14-utf16leBOM.ini
new file mode 100644
index 000000000..bbc3413aa
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser14-utf16leBOM.ini
diff --git a/xpcom/tests/unit/data/iniparser14-utf8BOM.ini b/xpcom/tests/unit/data/iniparser14-utf8BOM.ini
new file mode 100644
index 000000000..d109052c8
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser14-utf8BOM.ini
@@ -0,0 +1,6 @@
+[section1]
+name1=value1
+name2=value2
+[section2]
+name1=value1
+name2=foopy
diff --git a/xpcom/tests/unit/data/iniparser14.ini b/xpcom/tests/unit/data/iniparser14.ini
new file mode 100644
index 000000000..744af4cb6
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser14.ini
@@ -0,0 +1,6 @@
+[section1]

+name1=value1

+name2=value2

+[section2]

+name1=value1

+name2=foopy

diff --git a/xpcom/tests/unit/data/iniparser15-utf16leBOM.ini b/xpcom/tests/unit/data/iniparser15-utf16leBOM.ini
new file mode 100644
index 000000000..e60525dec
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser15-utf16leBOM.ini
diff --git a/xpcom/tests/unit/data/iniparser15-utf8BOM.ini b/xpcom/tests/unit/data/iniparser15-utf8BOM.ini
new file mode 100644
index 000000000..172803f90
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser15-utf8BOM.ini
@@ -0,0 +1,6 @@
+[section1]
+name1=value1
+[section2]
+name1=foopy
+[section1]
+name1=newValue1
diff --git a/xpcom/tests/unit/data/iniparser15.ini b/xpcom/tests/unit/data/iniparser15.ini
new file mode 100644
index 000000000..608a27d8f
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser15.ini
@@ -0,0 +1,6 @@
+[section1]

+name1=value1

+[section2]

+name1=foopy

+[section1]

+name1=newValue1

diff --git a/xpcom/tests/unit/data/iniparser16-utf16leBOM.ini b/xpcom/tests/unit/data/iniparser16-utf16leBOM.ini
new file mode 100644
index 000000000..142b17590
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser16-utf16leBOM.ini
diff --git a/xpcom/tests/unit/data/iniparser16-utf8BOM.ini b/xpcom/tests/unit/data/iniparser16-utf8BOM.ini
new file mode 100644
index 000000000..bba1018da
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser16-utf8BOM.ini
@@ -0,0 +1,13 @@
+#Ώ�ҳϖ·�˄ȡǨŅ©&
+[☺♫]
+#ѼΏ�ҳϖ
+♫=☻
+#·�˄ȡǨŅ©
+♪=♥
+#‽ἧᵿΏ�ҳ
+#ϖ·�˄ȡǨŅ©&
+[☼]
+♣=♠
+♦=♥
+#‽ἧᵿΏ�ҳ
+#·�˄ȡǨŅ©
diff --git a/xpcom/tests/unit/data/iniparser16.ini b/xpcom/tests/unit/data/iniparser16.ini
new file mode 100644
index 000000000..b94607d15
--- /dev/null
+++ b/xpcom/tests/unit/data/iniparser16.ini
@@ -0,0 +1,13 @@
+#Ώ�ҳϖ·�˄ȡǨŅ©&
+[☺♫]
+#ѼΏ�ҳϖ
+♫=☻
+#·�˄ȡǨŅ©
+♪=♥
+#‽ἧᵿΏ�ҳ
+#ϖ·�˄ȡǨŅ©&
+[☼]
+♣=♠
+♦=♥
+#‽ἧᵿΏ�ҳ
+#·�˄ȡǨŅ©
diff --git a/xpcom/tests/unit/data/main_process_directive_service.js b/xpcom/tests/unit/data/main_process_directive_service.js
new file mode 100644
index 000000000..f4eed11c9
--- /dev/null
+++ b/xpcom/tests/unit/data/main_process_directive_service.js
@@ -0,0 +1,21 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+Components.utils.import("resource:///modules/XPCOMUtils.jsm");
+
+function TestProcessDirective() {}
+TestProcessDirective.prototype = {
+
+  /* Boilerplate */
+  QueryInterface: XPCOMUtils.generateQI([Components.interfaces.nsISupportsString]),
+  contractID: "@mozilla.org/xpcom/tests/MainProcessDirectiveTest;1",
+  classID: Components.ID("{9b6f4160-45be-11e4-916c-0800200c9a66}"),
+
+  type: Components.interfaces.nsISupportsString.TYPE_STRING,
+  data: "main process",
+  toString: function() {
+    return this.data;
+  }
+};
+
+this.NSGetFactory = XPCOMUtils.generateNSGetFactory([TestProcessDirective]);
diff --git a/xpcom/tests/unit/data/presentation.key/.typeAttributes.dict b/xpcom/tests/unit/data/presentation.key/.typeAttributes.dict
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/xpcom/tests/unit/data/presentation.key/.typeAttributes.dict
diff --git a/xpcom/tests/unit/data/presentation.key/Contents/PkgInfo b/xpcom/tests/unit/data/presentation.key/Contents/PkgInfo
new file mode 100644
index 000000000..b0bc8e076
--- /dev/null
+++ b/xpcom/tests/unit/data/presentation.key/Contents/PkgInfo
@@ -0,0 +1 @@
+????????
\ No newline at end of file
diff --git a/xpcom/tests/unit/data/presentation.key/index.apxl.gz b/xpcom/tests/unit/data/presentation.key/index.apxl.gz
new file mode 100644
index 000000000..26178d809
--- /dev/null
+++ b/xpcom/tests/unit/data/presentation.key/index.apxl.gz
diff --git a/xpcom/tests/unit/data/presentation.key/thumbs/st0.tiff b/xpcom/tests/unit/data/presentation.key/thumbs/st0.tiff
new file mode 100644
index 000000000..8b49316b4
--- /dev/null
+++ b/xpcom/tests/unit/data/presentation.key/thumbs/st0.tiff
diff --git a/xpcom/tests/unit/data/process_directive.manifest b/xpcom/tests/unit/data/process_directive.manifest
new file mode 100644
index 000000000..9cbf7f241
--- /dev/null
+++ b/xpcom/tests/unit/data/process_directive.manifest
@@ -0,0 +1,5 @@
+component {9b6f4160-45be-11e4-916c-0800200c9a66} main_process_directive_service.js process=main
+contract @mozilla.org/xpcom/tests/MainProcessDirectiveTest;1 {9b6f4160-45be-11e4-916c-0800200c9a66} process=main
+
+component {4bd1ba60-45c4-11e4-916c-0800200c9a66} child_process_directive_service.js process=content
+contract @mozilla.org/xpcom/tests/ChildProcessDirectiveTest;1 {4bd1ba60-45c4-11e4-916c-0800200c9a66} process=content
diff --git a/xpcom/tests/unit/head_xpcom.js b/xpcom/tests/unit/head_xpcom.js
new file mode 100644
index 000000000..eacd5b4e6
--- /dev/null
+++ b/xpcom/tests/unit/head_xpcom.js
@@ -0,0 +1,21 @@
+function get_test_program(prog)
+{
+  var progPath = do_get_cwd();
+  progPath.append(prog);
+  progPath.leafName = progPath.leafName + mozinfo.bin_suffix;
+  return progPath;
+}
+
+function set_process_running_environment()
+{
+  var envSvc = Components.classes["@mozilla.org/process/environment;1"].
+    getService(Components.interfaces.nsIEnvironment);
+  var dirSvc = Components.classes["@mozilla.org/file/directory_service;1"].
+    getService(Components.interfaces.nsIProperties);
+  var greBinDir = dirSvc.get("GreBinD", Components.interfaces.nsIFile);
+  envSvc.set("DYLD_LIBRARY_PATH", greBinDir.path);
+  // For Linux
+  envSvc.set("LD_LIBRARY_PATH", greBinDir.path);
+  //XXX: handle windows
+}
+
diff --git a/xpcom/tests/unit/test_bug121341.js b/xpcom/tests/unit/test_bug121341.js
new file mode 100644
index 000000000..3aa04186e
--- /dev/null
+++ b/xpcom/tests/unit/test_bug121341.js
@@ -0,0 +1,71 @@
+var Ci = Components.interfaces;
+var Cu = Components.utils;
+Cu.import("resource://gre/modules/NetUtil.jsm");
+
+function run_test() {
+  var ios = Components.classes["@mozilla.org/network/io-service;1"].
+            getService(Components.interfaces.nsIIOService);
+                      
+  var dataFile = do_get_file("data/bug121341.properties");
+  var channel = NetUtil.newChannel({
+    uri: ios.newFileURI(dataFile, null, null),
+    loadUsingSystemPrincipal: true
+  });
+  var inp = channel.open2();
+
+  var properties = Components.classes["@mozilla.org/persistent-properties;1"].
+                   createInstance(Components.interfaces.nsIPersistentProperties);
+  properties.load(inp);
+
+  var value;
+
+  value = properties.getStringProperty("1");
+  do_check_eq(value, "abc");
+
+  value = properties.getStringProperty("2");
+  do_check_eq(value, "xy");
+
+  value = properties.getStringProperty("3");
+  do_check_eq(value, "\u1234\t\r\n\u00AB\u0001\n");
+
+  value = properties.getStringProperty("4");
+  do_check_eq(value, "this is multiline property");
+
+  value = properties.getStringProperty("5");
+  do_check_eq(value, "this is another multiline property");
+
+  value = properties.getStringProperty("6");
+  do_check_eq(value, "test\u0036");
+
+  value = properties.getStringProperty("7");
+  do_check_eq(value, "yet another multiline propery");
+
+  value = properties.getStringProperty("8");
+  do_check_eq(value, "\ttest5\u0020");
+
+  value = properties.getStringProperty("9");
+  do_check_eq(value, " test6\t");
+
+  value = properties.getStringProperty("10a\u1234b");
+  do_check_eq(value, "c\uCDEFd");
+
+  value = properties.getStringProperty("11");
+  do_check_eq(value, "\uABCD");
+
+  dataFile = do_get_file("data/bug121341-2.properties");
+
+  var channel = NetUtil.newChannel({
+    uri: ios.newFileURI(dataFile, null, null),
+    loadUsingSystemPrincipal: true
+  });
+  inp = channel.open2();
+
+  var properties2 = Components.classes["@mozilla.org/persistent-properties;1"].
+                    createInstance(Components.interfaces.nsIPersistentProperties);
+  try {
+    properties2.load(inp);
+    do_throw("load() didn't fail");
+  }
+  catch (e) {
+  }
+}
diff --git a/xpcom/tests/unit/test_bug325418.js b/xpcom/tests/unit/test_bug325418.js
new file mode 100644
index 000000000..b18866d7e
--- /dev/null
+++ b/xpcom/tests/unit/test_bug325418.js
@@ -0,0 +1,63 @@
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+
+// 5 seconds.
+const kExpectedDelay1 = 5;
+// 1 second.
+const kExpectedDelay2 = 1;
+
+var gStartTime1;
+var gStartTime2;
+var timer;
+
+var observer1 = {
+  observe: function observeTC1(subject, topic, data) {
+    if (topic == "timer-callback") {
+      // Stop timer, so it doesn't repeat (if test runs slowly).
+      timer.cancel();
+
+      // Actual delay may not be exact, so convert to seconds and round.
+      do_check_eq(Math.round((Date.now() - gStartTime1) / 1000),
+                  kExpectedDelay1);
+
+      timer = null;
+
+      do_print("1st timer triggered (before being cancelled). Should not have happened!");
+      do_check_true(false);
+    }
+  }
+};
+
+var observer2 = {
+  observe: function observeTC2(subject, topic, data) {
+    if (topic == "timer-callback") {
+      // Stop timer, so it doesn't repeat (if test runs slowly).
+      timer.cancel();
+
+      // Actual delay may not be exact, so convert to seconds and round.
+      do_check_eq(Math.round((Date.now() - gStartTime2) / 1000),
+                  kExpectedDelay2);
+
+      timer = null;
+
+      do_test_finished();
+    }
+  }
+};
+
+function run_test() {
+  do_test_pending();
+
+  timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
+
+  // Initialize the timer (with some delay), then cancel it.
+  gStartTime1 = Date.now();
+  timer.init(observer1, kExpectedDelay1 * 1000,
+             timer.TYPE_REPEATING_PRECISE_CAN_SKIP);
+  timer.cancel();
+
+  // Re-initialize the timer (with a different delay).
+  gStartTime2 = Date.now();
+  timer.init(observer2, kExpectedDelay2 * 1000,
+             timer.TYPE_REPEATING_PRECISE_CAN_SKIP);
+}
diff --git a/xpcom/tests/unit/test_bug332389.js b/xpcom/tests/unit/test_bug332389.js
new file mode 100644
index 000000000..91f8943e8
--- /dev/null
+++ b/xpcom/tests/unit/test_bug332389.js
@@ -0,0 +1,19 @@
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+
+function run_test() {
+  var f =
+      Cc["@mozilla.org/file/directory_service;1"].
+      getService(Ci.nsIProperties).get("CurProcD", Ci.nsIFile);
+
+  var terminated = false;
+  for (var i = 0; i < 100; i++) {
+    if (f == null) {
+      terminated = true;
+      break;
+    }
+    f = f.parent;
+  }
+
+  do_check_true(terminated);
+}
diff --git a/xpcom/tests/unit/test_bug333505.js b/xpcom/tests/unit/test_bug333505.js
new file mode 100644
index 000000000..856468605
--- /dev/null
+++ b/xpcom/tests/unit/test_bug333505.js
@@ -0,0 +1,10 @@
+function run_test()
+{
+  var dirEntries = do_get_cwd().directoryEntries;
+
+  while (dirEntries.hasMoreElements())
+    dirEntries.getNext();
+
+  // We ensure there is no crash
+  dirEntries.hasMoreElements();
+}
diff --git a/xpcom/tests/unit/test_bug364285-1.js b/xpcom/tests/unit/test_bug364285-1.js
new file mode 100644
index 000000000..f8bd6ee15
--- /dev/null
+++ b/xpcom/tests/unit/test_bug364285-1.js
@@ -0,0 +1,51 @@
+var Ci = Components.interfaces;
+var Cc = Components.classes;
+
+var nameArray = [
+ "ascii",                                           // ASCII
+ "fran\u00E7ais",                                   // Latin-1
+ "\u0420\u0443\u0441\u0441\u043A\u0438\u0439",      // Cyrillic
+ "\u65E5\u672C\u8A9E",                              // Japanese
+ "\u4E2D\u6587",                                    // Chinese
+ "\uD55C\uAD6D\uC5B4",                              // Korean
+ "\uD801\uDC0F\uD801\uDC2D\uD801\uDC3B\uD801\uDC2B" // Deseret
+];
+
+function getTempDir()
+{
+    var dirService = Cc["@mozilla.org/file/directory_service;1"]
+	.getService(Ci.nsIProperties);
+    return dirService.get("TmpD", Ci.nsILocalFile);
+}
+
+function create_file(fileName)
+{
+    var outFile = getTempDir();
+    outFile.append(fileName);
+    outFile.createUnique(outFile.NORMAL_FILE_TYPE, 0o600);
+
+    var stream = Cc["@mozilla.org/network/file-output-stream;1"]
+	.createInstance(Ci.nsIFileOutputStream);
+    stream.init(outFile, 0x02 | 0x08 | 0x20, 0o600, 0);
+    stream.write("foo", 3);
+    stream.close();
+
+    do_check_eq(outFile.leafName.substr(0, fileName.length), fileName);
+
+    return outFile;
+}
+
+function test_create(fileName)
+{
+    var file1 = create_file(fileName);
+    var file2 = create_file(fileName);
+    file1.remove(false);
+    file2.remove(false);
+}
+
+function run_test()
+{
+    for (var i = 0; i < nameArray.length; ++i) {
+	test_create(nameArray[i]);
+    }
+}
diff --git a/xpcom/tests/unit/test_bug374754.js b/xpcom/tests/unit/test_bug374754.js
new file mode 100644
index 000000000..9b0ccf26e
--- /dev/null
+++ b/xpcom/tests/unit/test_bug374754.js
@@ -0,0 +1,59 @@
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+
+var addedTopic = "xpcom-category-entry-added";
+var removedTopic = "xpcom-category-entry-removed";
+var testCategory = "bug-test-category";
+var testEntry = "@mozilla.org/bug-test-entry;1";
+
+var testValue= "check validity";
+var result = "";
+var expected = "add remove add remove ";
+var timer;
+
+var observer = {
+  QueryInterface: function(iid) {
+    if (iid.equals(Ci.nsISupports) || iid.equals(Ci.nsIObserver))
+      return this;
+
+    throw Components.results.NS_ERROR_NO_INTERFACE;
+  },
+
+  observe: function(subject, topic, data) {
+    if (topic == "timer-callback") {
+      do_check_eq(result, expected);
+
+      var observerService = Cc["@mozilla.org/observer-service;1"].getService(Ci.nsIObserverService);
+      observerService.removeObserver(this, addedTopic);
+      observerService.removeObserver(this, removedTopic);
+
+      do_test_finished();
+
+      timer = null;
+    }
+
+    if (subject.QueryInterface(Ci.nsISupportsCString).data != testEntry || data != testCategory)
+      return;
+
+    if (topic == addedTopic)
+      result += "add ";
+    else if (topic == removedTopic)
+      result += "remove ";
+  }
+};
+
+function run_test() {
+  do_test_pending();
+
+  var observerService = Cc["@mozilla.org/observer-service;1"].getService(Ci.nsIObserverService);
+  observerService.addObserver(observer, addedTopic, false);
+  observerService.addObserver(observer, removedTopic, false);
+
+  var categoryManager = Cc["@mozilla.org/categorymanager;1"].getService(Ci.nsICategoryManager);
+  categoryManager.addCategoryEntry(testCategory, testEntry, testValue, false, true);
+  categoryManager.addCategoryEntry(testCategory, testEntry, testValue, false, true);
+  categoryManager.deleteCategoryEntry(testCategory, testEntry, false);
+
+  timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
+  timer.init(observer, 0, timer.TYPE_ONE_SHOT);
+}
diff --git a/xpcom/tests/unit/test_bug476919.js b/xpcom/tests/unit/test_bug476919.js
new file mode 100644
index 000000000..21cd9253e
--- /dev/null
+++ b/xpcom/tests/unit/test_bug476919.js
@@ -0,0 +1,27 @@
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+
+function run_test() {
+  // skip this test on Windows
+  if (mozinfo.os != "win") {
+    var testDir = __LOCATION__.parent;
+    // create a test file, then symlink it, then check that we think it's a symlink
+    var targetFile = testDir.clone();
+    targetFile.append("target.txt");
+    if (!targetFile.exists())
+      targetFile.create(Ci.nsIFile.NORMAL_FILE_TYPE, 0o644);
+
+    var link = testDir.clone();
+    link.append("link");
+    if (link.exists())
+      link.remove(false);
+
+    var ln = Cc["@mozilla.org/file/local;1"].createInstance(Ci.nsILocalFile);
+    ln.initWithPath("/bin/ln");
+    var process = Cc["@mozilla.org/process/util;1"].createInstance(Ci.nsIProcess);
+    process.init(ln);
+    var args = ["-s", targetFile.path, link.path];
+    process.run(true, args, args.length);
+    do_check_true(link.isSymlink());
+  }
+}
diff --git a/xpcom/tests/unit/test_bug478086.js b/xpcom/tests/unit/test_bug478086.js
new file mode 100644
index 000000000..bd6ea0d08
--- /dev/null
+++ b/xpcom/tests/unit/test_bug478086.js
@@ -0,0 +1,24 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/  */
+
+function run_test() {
+  var nsILocalFile = Components.interfaces.nsILocalFile;
+  var root = Components.classes["@mozilla.org/file/local;1"].
+              createInstance(nsILocalFile);
+
+  // copied from http://mxr.mozilla.org/mozilla-central/source/image/test/unit/test_imgtools.js#135
+  // nsIXULRuntime.OS doesn't seem to be available in xpcshell, so we'll use
+  // this as a kludgy way to figure out if we're running on Windows.
+  if (mozinfo.os == "win") {
+    root.initWithPath("\\\\.");
+  } else {
+    return; // XXX disabled, since this causes intermittent failures on Mac (bug 481369).
+    root.initWithPath("/");
+  }
+  var drives = root.directoryEntries;
+  do_check_true(drives.hasMoreElements());
+  while (drives.hasMoreElements()) {
+    var newPath = drives.getNext().QueryInterface(nsILocalFile).path;
+    do_check_eq(newPath.indexOf("\0"), -1);
+  }
+}
diff --git a/xpcom/tests/unit/test_bug656331.js b/xpcom/tests/unit/test_bug656331.js
new file mode 100644
index 000000000..3bc1f82c0
--- /dev/null
+++ b/xpcom/tests/unit/test_bug656331.js
@@ -0,0 +1,39 @@
+Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
+
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+
+function info(s) {
+  dump("TEST-INFO | test_bug656331.js | " + s + "\n");
+}
+
+var gMessageExpected = /Native module.*has version 3.*expected/;
+var gFound = false;
+
+const kConsoleListener = {
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsIConsoleListener]),
+  
+  observe: function listener_observe(message) {
+    if (gMessageExpected.test(message.message))
+      gFound = true;
+  }
+};
+
+function run_test() {
+  let cs = Components.classes["@mozilla.org/consoleservice;1"].
+    getService(Ci.nsIConsoleService);
+  cs.registerListener(kConsoleListener);
+
+  let manifest = do_get_file('components/bug656331.manifest');
+  registerAppManifest(manifest);
+
+  do_check_false("{f18fb09b-28b4-4435-bc5b-8027f18df743}" in Components.classesByID);
+
+  do_test_pending();
+  Components.classes["@mozilla.org/thread-manager;1"].
+    getService(Ci.nsIThreadManager).mainThread.dispatch(function() {
+      cs.unregisterListener(kConsoleListener);
+      do_check_true(gFound);
+      do_test_finished();
+    }, 0);
+}
diff --git a/xpcom/tests/unit/test_bug725015.js b/xpcom/tests/unit/test_bug725015.js
new file mode 100644
index 000000000..d6f62c509
--- /dev/null
+++ b/xpcom/tests/unit/test_bug725015.js
@@ -0,0 +1,39 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+
+Components.utils.import("resource://gre/modules/Services.jsm");
+
+const manifest = do_get_file('bug725015.manifest');
+const contract = "@bug725015.test.contract";
+const observerTopic = "xpcom-category-entry-added";
+const category = "bug725015-test-category";
+const entry = "bug725015-category-entry";
+const cid = Components.ID("{05070380-6e6e-42ba-aaa5-3289fc55ca5a}");
+
+function observe_category(subj, topic, data) {
+  try {
+    do_check_eq(topic, observerTopic);
+    if (data != category)
+      return;
+  
+    var thisentry = subj.QueryInterface(Ci.nsISupportsCString).data;
+    do_check_eq(thisentry, entry);
+  
+    do_check_eq(Cc["@mozilla.org/categorymanager;1"].getService(Ci.nsICategoryManager).getCategoryEntry(category, entry), contract);
+    do_check_true(Cc[contract].equals(cid));
+  }
+  catch (e) {
+    do_throw(e);
+  }
+  do_test_finished();
+}
+
+function run_test() {
+  do_test_pending();
+  Services.obs.addObserver(observe_category, observerTopic, false);
+  Components.manager.QueryInterface(Ci.nsIComponentRegistrar).autoRegister(manifest);
+}
diff --git a/xpcom/tests/unit/test_bug745466.js b/xpcom/tests/unit/test_bug745466.js
new file mode 100644
index 000000000..22a911ac5
--- /dev/null
+++ b/xpcom/tests/unit/test_bug745466.js
@@ -0,0 +1,6 @@
+Components.utils.import("resource://gre/modules/FileUtils.jsm");
+
+function run_test()
+{
+  do_check_true(FileUtils.File("~").equals(FileUtils.getDir("Home", [])));
+}
diff --git a/xpcom/tests/unit/test_comp_no_aslr.js b/xpcom/tests/unit/test_comp_no_aslr.js
new file mode 100644
index 000000000..7e15731c6
--- /dev/null
+++ b/xpcom/tests/unit/test_comp_no_aslr.js
@@ -0,0 +1,18 @@
+Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
+
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+
+function run_test() {
+  let manifest = do_get_file('components/testcompnoaslr.manifest');
+  registerAppManifest(manifest);
+  var sysInfo = Cc["@mozilla.org/system-info;1"].
+                getService(Ci.nsIPropertyBag2);
+  var ver = parseFloat(sysInfo.getProperty("version"));
+  if (ver < 6.0) {
+    // This is disabled on pre-Vista OSs.
+    do_check_true("{335fb596-e52d-418f-b01c-1bf16ce5e7e4}" in Components.classesByID);
+  } else {
+    do_check_false("{335fb596-e52d-418f-b01c-1bf16ce5e7e4}" in Components.classesByID);
+  }
+}
diff --git a/xpcom/tests/unit/test_compmgr_warnings.js b/xpcom/tests/unit/test_compmgr_warnings.js
new file mode 100644
index 000000000..be77b0d1b
--- /dev/null
+++ b/xpcom/tests/unit/test_compmgr_warnings.js
@@ -0,0 +1,71 @@
+Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
+
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+
+function info(s) {
+  dump("TEST-INFO | test_compmgr_warnings.js | " + s + "\n");
+}
+
+var gMessagesExpected = [
+  { line: 2, message: /Malformed CID/, found: false },
+  { line: 6, message: /re-register/, found: false },
+  { line: 9, message: /Could not/, found: false },
+  { line: 2, message: /binary component twice/, found: false },
+  { line: 3, message: /binary component twice/, found: false },
+];
+
+const kConsoleListener = {
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsIConsoleListener]),
+
+  observe: function listener_observe(message) {
+    if (!(message instanceof Ci.nsIScriptError)) {
+      info("Not a script error: " + message.message);
+      return;
+    }
+
+    info("Script error... " + message.sourceName + ":" + message.lineNumber + ": " + message.errorMessage);
+    for (let expected of gMessagesExpected) {
+      if (message.lineNumber != expected.line)
+        continue;
+
+      if (!expected.message.test(message.errorMessage))
+        continue;
+
+      info("Found expected message: " + expected.message);
+      do_check_false(expected.found);
+                
+      expected.found = true;
+    }
+  }
+};
+
+function run_deferred_event(fn) {
+  do_test_pending();
+  Components.classes["@mozilla.org/thread-manager;1"].
+    getService(Ci.nsIThreadManager).mainThread.dispatch(function() {
+      fn();
+      do_test_finished();
+    }, 0);
+}
+
+function run_test()
+{
+  let cs = Components.classes["@mozilla.org/consoleservice;1"].
+    getService(Ci.nsIConsoleService);
+  cs.registerListener(kConsoleListener);
+
+  var manifest = do_get_file('compmgr_warnings.manifest');
+  registerAppManifest(manifest);
+  manifest = do_get_file('components/testcomponent.manifest');
+  registerAppManifest(manifest);
+
+  run_deferred_event(function() {
+    cs.unregisterListener(kConsoleListener);
+
+    for (let expected of gMessagesExpected) {
+      info("checking " + expected.message);
+      do_check_true(expected.found);
+    }
+  });
+}
diff --git a/xpcom/tests/unit/test_debugger_malloc_size_of.js b/xpcom/tests/unit/test_debugger_malloc_size_of.js
new file mode 100644
index 000000000..450d62793
--- /dev/null
+++ b/xpcom/tests/unit/test_debugger_malloc_size_of.js
@@ -0,0 +1,34 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// This is just a sanity test that Gecko is giving SpiderMonkey a MallocSizeOf
+// function for new JSRuntimes. There is more extensive testing around the
+// expected byte sizes within SpiderMonkey's jit-tests, we just want to make
+// sure that Gecko is providing SpiderMonkey with the callback it needs.
+
+var Cu = Components.utils;
+const { byteSize } = Cu.getJSTestingFunctions();
+
+function run_test()
+{
+  const objects = [
+    {},
+    { w: 1, x: 2, y: 3, z:4, a: 5 },
+    [],
+    Array(10).fill(null),
+    new RegExp("(2|two) problems", "g"),
+    new Date(),
+    new Uint8Array(64),
+    Promise.resolve(1),
+    function f() {},
+    Object
+  ];
+
+  for (let obj of objects) {
+    do_print(uneval(obj));
+    ok(byteSize(obj), "We should get some (non-zero) byte size");
+  }
+}
diff --git a/xpcom/tests/unit/test_file_createUnique.js b/xpcom/tests/unit/test_file_createUnique.js
new file mode 100644
index 000000000..1ab204bab
--- /dev/null
+++ b/xpcom/tests/unit/test_file_createUnique.js
@@ -0,0 +1,29 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+var Cr = Components.results;
+
+function run_test()
+{
+  // Generate a leaf name that is 255 characters long.
+  var longLeafName = new Array(256).join("T");
+
+  // Generate the path for a file located in a directory with a long name.
+  var tempFile = Cc["@mozilla.org/file/directory_service;1"].
+                 getService(Ci.nsIProperties).get("TmpD", Ci.nsIFile);
+  tempFile.append(longLeafName);
+  tempFile.append("test.txt");
+
+  try {
+    tempFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o600);
+    do_throw("Creating an item in a folder with a very long name should throw");
+  }
+  catch (e if (e instanceof Ci.nsIException &&
+               e.result == Cr.NS_ERROR_FILE_UNRECOGNIZED_PATH)) {
+    // We expect the function not to crash but to raise this exception.
+  }
+}
diff --git a/xpcom/tests/unit/test_file_equality.js b/xpcom/tests/unit/test_file_equality.js
new file mode 100644
index 000000000..235792560
--- /dev/null
+++ b/xpcom/tests/unit/test_file_equality.js
@@ -0,0 +1,43 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+var Cr = Components.results;
+var Ci = Components.interfaces;
+
+var CC = Components.Constructor;
+var LocalFile = CC("@mozilla.org/file/local;1", "nsILocalFile", "initWithPath");
+
+function run_test()
+{
+  test_normalized_vs_non_normalized();
+}
+
+function test_normalized_vs_non_normalized()
+{
+  // get a directory that exists on all platforms
+  var dirProvider = Components.classes["@mozilla.org/file/directory_service;1"].getService(Ci.nsIProperties);
+  var tmp1 = dirProvider.get("TmpD", Ci.nsILocalFile);
+  var exists = tmp1.exists();
+  do_check_true(exists);
+  if (!exists)
+    return;
+
+  // the test logic below assumes we're starting with a normalized path, but the
+  // default location on macos is a symbolic link, so resolve it before starting
+  tmp1.normalize();
+
+  // this has the same exact path as tmp1, it should equal tmp1
+  var tmp2 = new LocalFile(tmp1.path);
+  do_check_true(tmp1.equals(tmp2));
+
+  // this is a non-normalized version of tmp1, it should not equal tmp1
+  tmp2.appendRelativePath(".");
+  do_check_false(tmp1.equals(tmp2));
+
+  // normalize and make sure they are equivalent again
+  tmp2.normalize();
+  do_check_true(tmp1.equals(tmp2));
+}
diff --git a/xpcom/tests/unit/test_file_renameTo.js b/xpcom/tests/unit/test_file_renameTo.js
new file mode 100644
index 000000000..0a7196fe2
--- /dev/null
+++ b/xpcom/tests/unit/test_file_renameTo.js
@@ -0,0 +1,61 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+
+function run_test()
+{
+  // Create the base directory.
+  let base = Cc['@mozilla.org/file/directory_service;1']
+             .getService(Ci.nsIProperties)
+             .get('TmpD', Ci.nsILocalFile);
+  base.append('renameTesting');
+  if (base.exists()) {
+    base.remove(true);
+  }
+  base.create(Ci.nsIFile.DIRECTORY_TYPE, parseInt('0777', 8));
+
+  // Create a sub directory under the base.
+  let subdir = base.clone();
+  subdir.append('subdir');
+  subdir.create(Ci.nsIFile.DIRECTORY_TYPE, parseInt('0777', 8));
+
+  // Create a file under the sub directory.
+  let tempFile = subdir.clone();
+  tempFile.append('file0.txt');
+  tempFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, parseInt('0777', 8));
+
+  // Test renameTo in the base directory
+  tempFile.renameTo(null, 'file1.txt');
+  do_check_true(exists(subdir, 'file1.txt'));
+
+  // Test moving across directories
+  tempFile = subdir.clone();
+  tempFile.append('file1.txt');
+  tempFile.renameTo(base, '');
+  do_check_true(exists(base, 'file1.txt'));
+
+  // Test moving across directories and renaming at the same time
+  tempFile = base.clone();
+  tempFile.append('file1.txt');
+  tempFile.renameTo(subdir, 'file2.txt');
+  do_check_true(exists(subdir, 'file2.txt'));
+
+  // Test moving a directory
+  subdir.renameTo(base, 'renamed');
+  do_check_true(exists(base, 'renamed'));
+  let renamed = base.clone();
+  renamed.append('renamed');
+  do_check_true(exists(renamed, 'file2.txt'));
+
+  base.remove(true);
+}
+
+function exists(parent, filename) {
+  let file = parent.clone();
+  file.append(filename);
+  return file.exists();
+}
diff --git a/xpcom/tests/unit/test_hidden_files.js b/xpcom/tests/unit/test_hidden_files.js
new file mode 100644
index 000000000..3383ba11b
--- /dev/null
+++ b/xpcom/tests/unit/test_hidden_files.js
@@ -0,0 +1,28 @@
+var Ci = Components.interfaces;
+var Cc = Components.classes;
+const NS_OS_TEMP_DIR = "TmpD";
+
+const CWD = do_get_cwd();
+
+var hiddenUnixFile;
+function createUNIXHiddenFile() {
+  var dirSvc = Cc["@mozilla.org/file/directory_service;1"].getService(Ci.nsIProperties);
+  var tmpDir = dirSvc.get(NS_OS_TEMP_DIR, Ci.nsIFile);
+  hiddenUnixFile = tmpDir.clone();
+  hiddenUnixFile.append(".foo");
+  // we don't care if this already exists because we don't care
+  // about the file's contents (just the name)
+  if (!hiddenUnixFile.exists())
+    hiddenUnixFile.create(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+  return hiddenUnixFile.exists();
+}
+
+function run_test() {
+  // Skip this test on Windows
+  if (mozinfo.os == "win")
+    return;
+
+  do_check_true(createUNIXHiddenFile());
+  do_check_true(hiddenUnixFile.isHidden());
+}
+
diff --git a/xpcom/tests/unit/test_home.js b/xpcom/tests/unit/test_home.js
new file mode 100644
index 000000000..61fa5b344
--- /dev/null
+++ b/xpcom/tests/unit/test_home.js
@@ -0,0 +1,24 @@
+var Ci = Components.interfaces;
+var Cc = Components.classes;
+
+const CWD = do_get_cwd();
+function checkOS(os) {
+  const nsILocalFile_ = "nsILocalFile" + os;
+  return nsILocalFile_ in Components.interfaces &&
+         CWD instanceof Components.interfaces[nsILocalFile_];
+}
+
+const isWin = checkOS("Win");
+
+function run_test() {
+  var envVar = isWin ? "USERPROFILE" : "HOME";
+
+  var dirSvc = Cc["@mozilla.org/file/directory_service;1"].getService(Ci.nsIProperties);
+  var homeDir = dirSvc.get("Home", Ci.nsIFile);
+
+  var env = Cc["@mozilla.org/process/environment;1"].getService(Ci.nsIEnvironment);
+  var expected = Cc["@mozilla.org/file/local;1"].createInstance(Ci.nsILocalFile);
+  expected.initWithPath(env.get(envVar));
+
+  do_check_eq(homeDir.path, expected.path);
+}
diff --git a/xpcom/tests/unit/test_iniProcessor.js b/xpcom/tests/unit/test_iniProcessor.js
new file mode 100644
index 000000000..3d3886d35
--- /dev/null
+++ b/xpcom/tests/unit/test_iniProcessor.js
@@ -0,0 +1,288 @@
+var Ci = Components.interfaces;
+var Cc = Components.classes;
+var Cr = Components.results;
+
+var testnum = 0;
+var factory;
+
+function parserForFile(filename) {
+    let parser = null;
+    try {
+        let file = do_get_file(filename);
+        do_check_true(!!file);
+        parser = factory.createINIParser(file);
+        do_check_true(!!parser);
+    } catch(e) {
+	dump("INFO | caught error: " + e);
+        // checkParserOutput will handle a null parser when it's expected.
+    }
+    return parser;
+    
+}
+
+function checkParserOutput(parser, expected) {
+    // If the expected output is null, we expect the parser to have
+    // failed (and vice-versa).
+    if (!parser || !expected) {
+        do_check_eq(parser, null);
+        do_check_eq(expected, null);
+        return;
+    }
+
+    let output = getParserOutput(parser);
+    for (let section in expected) {
+        do_check_true(section in output);
+        for (let key in expected[section]) {
+            do_check_true(key in output[section]);
+            do_check_eq(output[section][key], expected[section][key]);
+            delete output[section][key];
+        }
+        for (let key in output[section])
+            do_check_eq(key, "wasn't expecting this key!");
+        delete output[section];
+    }
+    for (let section in output)
+        do_check_eq(section, "wasn't expecting this section!");
+}
+
+function getParserOutput(parser) {
+    let output = {};
+
+    let sections = parser.getSections();
+    do_check_true(!!sections);
+    while (sections.hasMore()) {
+        let section = sections.getNext();
+        do_check_false(section in output); // catch dupes
+        output[section] = {};
+
+        let keys = parser.getKeys(section);
+        do_check_true(!!keys);
+        while (keys.hasMore()) {
+            let key = keys.getNext();
+            do_check_false(key in output[section]); // catch dupes
+            let value = parser.getString(section, key);
+            output[section][key] = value;
+        }
+    }
+    return output;
+}
+
+function run_test() {
+try {
+
+var testdata = [
+    { filename: "data/iniparser01.ini", reference: {} },
+    { filename: "data/iniparser02.ini", reference: {} },
+    { filename: "data/iniparser03.ini", reference: {} },
+    { filename: "data/iniparser04.ini", reference: {} },
+    { filename: "data/iniparser05.ini", reference: {} },
+    { filename: "data/iniparser06.ini", reference: {} },
+    { filename: "data/iniparser07.ini", reference: {} },
+    { filename: "data/iniparser08.ini", reference: { section1: { name1: "" }} },
+    { filename: "data/iniparser09.ini", reference: { section1: { name1: "value1" } } },
+    { filename: "data/iniparser10.ini", reference: { section1: { name1: "value1" } } },
+    { filename: "data/iniparser11.ini", reference: { section1: { name1: "value1" } } },
+    { filename: "data/iniparser12.ini", reference: { section1: { name1: "value1" } } },
+    { filename: "data/iniparser13.ini", reference: { section1: { name1: "value1" } } },
+    { filename: "data/iniparser14.ini", reference: 
+                    { section1: { name1: "value1", name2: "value2" },
+                      section2: { name1: "value1", name2: "foopy"  }} },
+    { filename: "data/iniparser15.ini", reference: 
+                    { section1: { name1: "newValue1" },
+                      section2: { name1: "foopy"     }} },
+    { filename: "data/iniparser16.ini", reference: 
+                    { "☺♫": { "♫": "☻", "♪": "♥"  },
+                       "☼": { "♣": "♠", "♦": "♥"  }} },
+
+    ];
+
+    testdata.push( { filename: "data/iniparser01-utf8BOM.ini",
+                     reference: testdata[0].reference } );
+    testdata.push( { filename: "data/iniparser02-utf8BOM.ini",
+                     reference: testdata[1].reference } );
+    testdata.push( { filename: "data/iniparser03-utf8BOM.ini",
+                     reference: testdata[2].reference } );
+    testdata.push( { filename: "data/iniparser04-utf8BOM.ini",
+                     reference: testdata[3].reference } );
+    testdata.push( { filename: "data/iniparser05-utf8BOM.ini",
+                     reference: testdata[4].reference } );
+    testdata.push( { filename: "data/iniparser06-utf8BOM.ini",
+                     reference: testdata[5].reference } );
+    testdata.push( { filename: "data/iniparser07-utf8BOM.ini",
+                     reference: testdata[6].reference } );
+    testdata.push( { filename: "data/iniparser08-utf8BOM.ini",
+                     reference: testdata[7].reference } );
+    testdata.push( { filename: "data/iniparser09-utf8BOM.ini",
+                     reference: testdata[8].reference } );
+    testdata.push( { filename: "data/iniparser10-utf8BOM.ini",
+                     reference: testdata[9].reference } );
+    testdata.push( { filename: "data/iniparser11-utf8BOM.ini",
+                     reference: testdata[10].reference } );
+    testdata.push( { filename: "data/iniparser12-utf8BOM.ini",
+                     reference: testdata[11].reference } );
+    testdata.push( { filename: "data/iniparser13-utf8BOM.ini",
+                     reference: testdata[12].reference } );
+    testdata.push( { filename: "data/iniparser14-utf8BOM.ini",
+                     reference: testdata[13].reference } );
+    testdata.push( { filename: "data/iniparser15-utf8BOM.ini",
+                     reference: testdata[14].reference } );
+    testdata.push( { filename: "data/iniparser16-utf8BOM.ini",
+                     reference: testdata[15].reference } );
+
+    let os = Cc["@mozilla.org/xre/app-info;1"]
+             .getService(Ci.nsIXULRuntime).OS;
+    if("WINNT" === os) {
+        testdata.push( { filename: "data/iniparser01-utf16leBOM.ini",
+                         reference: testdata[0].reference } );
+        testdata.push( { filename: "data/iniparser02-utf16leBOM.ini",
+                         reference: testdata[1].reference } );
+        testdata.push( { filename: "data/iniparser03-utf16leBOM.ini",
+                         reference: testdata[2].reference } );
+        testdata.push( { filename: "data/iniparser04-utf16leBOM.ini",
+                         reference: testdata[3].reference } );
+        testdata.push( { filename: "data/iniparser05-utf16leBOM.ini",
+                         reference: testdata[4].reference } );
+        testdata.push( { filename: "data/iniparser06-utf16leBOM.ini",
+                         reference: testdata[5].reference } );
+        testdata.push( { filename: "data/iniparser07-utf16leBOM.ini",
+                         reference: testdata[6].reference } );
+        testdata.push( { filename: "data/iniparser08-utf16leBOM.ini",
+                         reference: testdata[7].reference } );
+        testdata.push( { filename: "data/iniparser09-utf16leBOM.ini",
+                         reference: testdata[8].reference } );
+        testdata.push( { filename: "data/iniparser10-utf16leBOM.ini",
+                         reference: testdata[9].reference } );
+        testdata.push( { filename: "data/iniparser11-utf16leBOM.ini",
+                         reference: testdata[10].reference } );
+        testdata.push( { filename: "data/iniparser12-utf16leBOM.ini",
+                         reference: testdata[11].reference } );
+        testdata.push( { filename: "data/iniparser13-utf16leBOM.ini",
+                         reference: testdata[12].reference } );
+        testdata.push( { filename: "data/iniparser14-utf16leBOM.ini",
+                         reference: testdata[13].reference } );
+        testdata.push( { filename: "data/iniparser15-utf16leBOM.ini",
+                         reference: testdata[14].reference } );
+        testdata.push( { filename: "data/iniparser16-utf16leBOM.ini",
+                         reference: testdata[15].reference } );
+    }
+
+/* ========== 0 ========== */
+factory = Cc["@mozilla.org/xpcom/ini-processor-factory;1"].
+          getService(Ci.nsIINIParserFactory);
+do_check_true(!!factory);
+
+// Test reading from a variety of files. While we're at it, write out each one
+// and read it back to ensure that nothing changed.
+while (testnum < testdata.length) {
+    dump("\nINFO | test #" + ++testnum);
+    let filename = testdata[testnum -1].filename;
+    dump(", filename " + filename + "\n");
+    let parser = parserForFile(filename);
+    checkParserOutput(parser, testdata[testnum - 1].reference);
+    if (!parser)
+        continue;
+    do_check_true(parser instanceof Ci.nsIINIParserWriter);
+    // write contents out to a new file
+    let newfilename = filename + ".new";
+    let newfile = do_get_file(filename);
+    newfile.leafName += ".new";
+    parser.writeFile(newfile);
+    // read new file and make sure the contents are the same.
+    parser = parserForFile(newfilename);
+    checkParserOutput(parser, testdata[testnum - 1].reference);
+    // cleanup after the test
+    newfile.remove(false);
+}
+
+dump("INFO | test #" + ++testnum + "\n");
+
+// test writing to a new file.
+var newfile = do_get_file("data/");
+newfile.append("nonexistent-file.ini");
+if (newfile.exists())
+    newfile.remove(false);
+do_check_false(newfile.exists());
+
+var parser = factory.createINIParser(newfile);
+do_check_true(!!parser);
+do_check_true(parser instanceof Ci.nsIINIParserWriter);
+checkParserOutput(parser, {});
+parser.writeFile();
+do_check_true(newfile.exists());
+
+// test adding a new section and new key
+parser.setString("section", "key", "value");
+parser.writeFile();
+do_check_true(newfile.exists());
+checkParserOutput(parser, {section: {key: "value"} });
+// read it in again, check for same data.
+parser = parserForFile("data/nonexistent-file.ini");
+checkParserOutput(parser, {section: {key: "value"} });
+// cleanup after the test
+newfile.remove(false);
+
+dump("INFO | test #" + ++testnum + "\n");
+
+// test modifying a existing key's value (in an existing section)
+parser = parserForFile("data/iniparser09.ini");
+checkParserOutput(parser, {section1: {name1: "value1"} });
+
+do_check_true(parser instanceof Ci.nsIINIParserWriter);
+parser.setString("section1", "name1", "value2");
+checkParserOutput(parser, {section1: {name1: "value2"} });
+
+dump("INFO | test #" + ++testnum + "\n");
+
+// test trying to set illegal characters
+var caughtError;
+caughtError = false;
+checkParserOutput(parser, {section1: {name1: "value2"} });
+
+// Bad characters in section name
+try { parser.SetString("bad\0", "ok", "ok"); } catch (e) { caughtError = true; }
+do_check_true(caughtError);
+caughtError = false;
+try { parser.SetString("bad\r", "ok", "ok"); } catch (e) { caughtError = true; }
+do_check_true(caughtError);
+caughtError = false;
+try { parser.SetString("bad\n", "ok", "ok"); } catch (e) { caughtError = true; }
+do_check_true(caughtError);
+caughtError = false;
+try { parser.SetString("bad[", "ok", "ok"); } catch (e) { caughtError = true; }
+do_check_true(caughtError);
+caughtError = false;
+try { parser.SetString("bad]", "ok", "ok"); } catch (e) { caughtError = true; }
+do_check_true(caughtError);
+
+// Bad characters in key name
+caughtError = false;
+try { parser.SetString("ok", "bad\0", "ok"); } catch (e) { caughtError = true; }
+do_check_true(caughtError);
+caughtError = false;
+try { parser.SetString("ok", "bad\r", "ok"); } catch (e) { caughtError = true; }
+do_check_true(caughtError);
+caughtError = false;
+try { parser.SetString("ok", "bad\n", "ok"); } catch (e) { caughtError = true; }
+do_check_true(caughtError);
+caughtError = false;
+try { parser.SetString("ok", "bad=", "ok"); } catch (e) { caughtError = true; }
+do_check_true(caughtError);
+
+// Bad characters in value
+caughtError = false;
+try { parser.SetString("ok", "ok", "bad\0"); } catch (e) { caughtError = true; }
+do_check_true(caughtError);
+caughtError = false;
+try { parser.SetString("ok", "ok", "bad\r"); } catch (e) { caughtError = true; }
+do_check_true(caughtError);
+caughtError = false;
+try { parser.SetString("ok", "ok", "bad\n"); } catch (e) { caughtError = true; }
+do_check_true(caughtError);
+caughtError = false;
+try { parser.SetString("ok", "ok", "bad="); } catch (e) { caughtError = true; }
+do_check_true(caughtError);
+
+} catch(e) {
+    throw "FAILED in test #" + testnum + " -- " + e;
+}
+}
diff --git a/xpcom/tests/unit/test_ioutil.js b/xpcom/tests/unit/test_ioutil.js
new file mode 100644
index 000000000..ef27f584f
--- /dev/null
+++ b/xpcom/tests/unit/test_ioutil.js
@@ -0,0 +1,33 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+var Cr = Components.results;
+
+const util = Cc["@mozilla.org/io-util;1"].getService(Ci.nsIIOUtil);
+
+function run_test()
+{
+    try {
+        util.inputStreamIsBuffered(null);
+        do_throw("inputStreamIsBuffered should have thrown");
+    } catch (e) {
+        do_check_eq(e.result, Cr.NS_ERROR_INVALID_POINTER);
+    }
+
+    try {
+        util.outputStreamIsBuffered(null);
+        do_throw("outputStreamIsBuffered should have thrown");
+    } catch (e) {
+        do_check_eq(e.result, Cr.NS_ERROR_INVALID_POINTER);
+    }
+
+    var s = Cc["@mozilla.org/io/string-input-stream;1"]
+              .createInstance(Ci.nsIStringInputStream);
+    var body = "This is a test";
+    s.setData(body, body.length);
+    do_check_eq(util.inputStreamIsBuffered(s), true);
+}
diff --git a/xpcom/tests/unit/test_localfile.js b/xpcom/tests/unit/test_localfile.js
new file mode 100644
index 000000000..25f4bf34b
--- /dev/null
+++ b/xpcom/tests/unit/test_localfile.js
@@ -0,0 +1,151 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+var Cr = Components.results;
+var CC = Components.Constructor;
+var Ci = Components.interfaces;
+
+const MAX_TIME_DIFFERENCE = 2500;
+const MILLIS_PER_DAY      = 1000 * 60 * 60 * 24;
+
+var LocalFile = CC("@mozilla.org/file/local;1", "nsILocalFile", "initWithPath");
+
+function run_test()
+{
+  test_toplevel_parent_is_null();
+  test_normalize_crash_if_media_missing();
+  test_file_modification_time();
+  test_directory_modification_time();
+  test_diskSpaceAvailable();
+}
+
+function test_toplevel_parent_is_null()
+{
+  try
+  {
+    var lf = new LocalFile("C:\\");
+
+    // not required by API, but a property on which the implementation of
+    // parent == null relies for correctness
+    do_check_true(lf.path.length == 2);
+
+    do_check_true(lf.parent === null);
+  }
+  catch (e)
+  {
+    // not Windows
+    do_check_eq(e.result, Cr.NS_ERROR_FILE_UNRECOGNIZED_PATH);
+  }
+}
+
+function test_normalize_crash_if_media_missing()
+{
+  const a="a".charCodeAt(0);
+  const z="z".charCodeAt(0);
+  for (var i = a; i <= z; ++i)
+  {
+    try
+    {
+      LocalFile(String.fromCharCode(i)+":.\\test").normalize();
+    }
+    catch (e)
+    {
+    }
+  }
+}
+
+// Tests that changing a file's modification time is possible   
+function test_file_modification_time()
+{
+  var file = do_get_profile();
+  file.append("testfile");
+
+  // Should never happen but get rid of it anyway
+  if (file.exists())
+    file.remove(true);
+
+  var now = Date.now();
+  file.create(Ci.nsIFile.NORMAL_FILE_TYPE, 0o644);
+  do_check_true(file.exists());
+
+  // Modification time may be out by up to 2 seconds on FAT filesystems. Test
+  // with a bit of leeway, close enough probably means it is correct.
+  var diff = Math.abs(file.lastModifiedTime - now);
+  do_check_true(diff < MAX_TIME_DIFFERENCE);
+
+  var yesterday = now - MILLIS_PER_DAY;
+  file.lastModifiedTime = yesterday;
+
+  diff = Math.abs(file.lastModifiedTime - yesterday);
+  do_check_true(diff < MAX_TIME_DIFFERENCE);
+
+  var tomorrow = now - MILLIS_PER_DAY;
+  file.lastModifiedTime = tomorrow;
+
+  diff = Math.abs(file.lastModifiedTime - tomorrow);
+  do_check_true(diff < MAX_TIME_DIFFERENCE);
+
+  var bug377307 = 1172950238000;
+  file.lastModifiedTime = bug377307;
+
+  diff = Math.abs(file.lastModifiedTime - bug377307);
+  do_check_true(diff < MAX_TIME_DIFFERENCE);
+
+  file.remove(true);
+}
+
+// Tests that changing a directory's modification time is possible   
+function test_directory_modification_time()
+{
+  var dir = do_get_profile();
+  dir.append("testdir");
+
+  // Should never happen but get rid of it anyway
+  if (dir.exists())
+    dir.remove(true);
+
+  var now = Date.now();
+  dir.create(Ci.nsIFile.DIRECTORY_TYPE, 0o755);
+  do_check_true(dir.exists());
+
+  // Modification time may be out by up to 2 seconds on FAT filesystems. Test
+  // with a bit of leeway, close enough probably means it is correct.
+  var diff = Math.abs(dir.lastModifiedTime - now);
+  do_check_true(diff < MAX_TIME_DIFFERENCE);
+
+  var yesterday = now - MILLIS_PER_DAY;
+  dir.lastModifiedTime = yesterday;
+
+  diff = Math.abs(dir.lastModifiedTime - yesterday);
+  do_check_true(diff < MAX_TIME_DIFFERENCE);
+
+  var tomorrow = now - MILLIS_PER_DAY;
+  dir.lastModifiedTime = tomorrow;
+
+  diff = Math.abs(dir.lastModifiedTime - tomorrow);
+  do_check_true(diff < MAX_TIME_DIFFERENCE);
+
+  dir.remove(true);
+}
+
+function test_diskSpaceAvailable()
+{
+  let file = do_get_profile();
+  file.QueryInterface(Ci.nsILocalFile);
+
+  let bytes = file.diskSpaceAvailable;
+  do_check_true(bytes > 0);
+
+  file.append("testfile");
+  if (file.exists())
+    file.remove(true);
+  file.create(Ci.nsIFile.NORMAL_FILE_TYPE, 0o644);
+
+  bytes = file.diskSpaceAvailable;
+  do_check_true(bytes > 0);
+
+  file.remove(true);
+}
diff --git a/xpcom/tests/unit/test_mac_bundle.js b/xpcom/tests/unit/test_mac_bundle.js
new file mode 100644
index 000000000..550a4abd6
--- /dev/null
+++ b/xpcom/tests/unit/test_mac_bundle.js
@@ -0,0 +1,18 @@
+function run_test() { 
+  // this is a hack to skip the rest of the code on non-Mac platforms, 
+  // since #ifdef is not available to xpcshell tests...
+  if (mozinfo.os != "mac") {
+    return;
+  }
+  
+  // OK, here's the real part of the test:
+  // make sure these two test bundles are recognized as bundles (or "packages") 
+  var keynoteBundle = do_get_file("data/presentation.key");
+  var appBundle = do_get_file("data/SmallApp.app");
+  
+  do_check_true(keynoteBundle instanceof Components.interfaces.nsILocalFileMac);
+  do_check_true(appBundle instanceof Components.interfaces.nsILocalFileMac);
+  
+  do_check_true(keynoteBundle.isPackage());
+  do_check_true(appBundle.isPackage());
+}
diff --git a/xpcom/tests/unit/test_notxpcom_scriptable.js b/xpcom/tests/unit/test_notxpcom_scriptable.js
new file mode 100644
index 000000000..5d5e24bd9
--- /dev/null
+++ b/xpcom/tests/unit/test_notxpcom_scriptable.js
@@ -0,0 +1,86 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+var Cu = Components.utils;
+var Cr = Components.results;
+
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+
+const kCID = Components.ID("{1f9f7181-e6c5-4f4c-8f71-08005cec8468}");
+const kContract = "@testing/notxpcomtest";
+
+function run_test()
+{
+  let manifest = do_get_file("xpcomtest.manifest");
+  let registrar = Components.manager.QueryInterface(Ci.nsIComponentRegistrar);
+  registrar.autoRegister(manifest);
+
+  ok(Ci.ScriptableWithNotXPCOM);
+
+  let method1Called = false;
+
+  let testObject = {
+    QueryInterface: XPCOMUtils.generateQI([Ci.ScriptableOK,
+                                           Ci.ScriptableWithNotXPCOM,
+                                           Ci.ScriptableWithNotXPCOMBase]),
+
+    method1: function() {
+      method1Called = true;
+    },
+
+    method2: function() {
+      ok(false, "method2 should not have been called!");
+    },
+
+    method3: function() {
+      ok(false, "mehod3 should not have been called!");
+    },
+
+    jsonly: true,
+  };
+
+  let factory = {
+    QueryInterface: XPCOMUtils.generateQI([Ci.nsIFactory]),
+
+    createInstance: function(outer, iid) {
+      if (outer) {
+        throw Cr.NS_ERROR_NO_AGGREGATION;
+      }
+      return testObject.QueryInterface(iid);
+    },
+  };
+
+  registrar.registerFactory(kCID, null, kContract, factory);
+
+  let xpcomObject = Cc[kContract].createInstance();
+  ok(xpcomObject);
+  strictEqual(xpcomObject.jsonly, undefined);
+
+  xpcomObject.QueryInterface(Ci.ScriptableOK);
+
+  xpcomObject.method1();
+  ok(method1Called);
+
+  try {
+    xpcomObject.QueryInterface(Ci.ScriptableWithNotXPCOM);
+    ok(false, "Should not have implemented ScriptableWithNotXPCOM");
+  }
+  catch(e) {
+    ok(true, "Should not have implemented ScriptableWithNotXPCOM. Correctly threw error: " + e);
+  }
+  strictEqual(xpcomObject.method2, undefined);
+
+  try {
+    xpcomObject.QueryInterface(Ci.ScriptableWithNotXPCOMBase);
+    ok(false, "Should not have implemented ScriptableWithNotXPCOMBase");
+  }
+  catch (e) {
+    ok(true, "Should not have implemented ScriptableWithNotXPCOMBase. Correctly threw error: " + e);
+  }
+  strictEqual(xpcomObject.method3, undefined);
+}
+
diff --git a/xpcom/tests/unit/test_nsIMutableArray.js b/xpcom/tests/unit/test_nsIMutableArray.js
new file mode 100644
index 000000000..b491aee96
--- /dev/null
+++ b/xpcom/tests/unit/test_nsIMutableArray.js
@@ -0,0 +1,184 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+var Ci = Components.interfaces;
+var Cr = Components.results;
+var Cc = Components.classes;
+var CC = Components.Constructor;
+
+var MutableArray = CC("@mozilla.org/array;1", "nsIMutableArray");
+var SupportsString = CC("@mozilla.org/supports-string;1", "nsISupportsString");
+
+function create_n_element_array(n)
+{
+  var arr = new MutableArray();
+  for (let i=0; i<n; i++) {
+    let str = new SupportsString();
+    str.data = "element " + i;
+    arr.appendElement(str, false);
+  }
+  return arr;
+}
+
+function test_appending_null_actually_inserts()
+{
+  var arr = new MutableArray();
+  do_check_eq(0, arr.length);
+  arr.appendElement(null, false);
+  do_check_eq(1, arr.length);
+}
+
+function test_object_gets_appended()
+{
+  var arr = new MutableArray();
+  var str = new SupportsString();
+  str.data = "hello";
+  arr.appendElement(str, false);
+  do_check_eq(1, arr.length);
+  var obj = arr.queryElementAt(0, Ci.nsISupportsString);
+  do_check_eq(str, obj);
+}
+
+function test_insert_at_beginning()
+{
+  var arr = create_n_element_array(5);
+  // just a sanity check
+  do_check_eq(5, arr.length);
+  var str = new SupportsString();
+  str.data = "hello";
+  arr.insertElementAt(str, 0, false);
+  do_check_eq(6, arr.length);
+  var obj = arr.queryElementAt(0, Ci.nsISupportsString);
+  do_check_eq(str, obj);
+  // check the data of all the other objects
+  for (let i=1; i<arr.length; i++) {
+    let obj = arr.queryElementAt(i, Ci.nsISupportsString);
+    do_check_eq("element " + (i-1), obj.data);
+  }
+}
+
+function test_replace_element()
+{
+  var arr = create_n_element_array(5);
+  // just a sanity check
+  do_check_eq(5, arr.length);
+  var str = new SupportsString();
+  str.data = "hello";
+  // replace first element
+  arr.replaceElementAt(str, 0, false);
+  do_check_eq(5, arr.length);
+  var obj = arr.queryElementAt(0, Ci.nsISupportsString);
+  do_check_eq(str, obj);
+  // replace last element
+  arr.replaceElementAt(str, arr.length - 1, false);
+  do_check_eq(5, arr.length);
+  obj = arr.queryElementAt(arr.length - 1, Ci.nsISupportsString);
+  do_check_eq(str, obj);
+  // replace after last element, should insert empty elements
+  arr.replaceElementAt(str, 9, false);
+  do_check_eq(10, arr.length);
+  obj = arr.queryElementAt(9, Ci.nsISupportsString);
+  do_check_eq(str, obj);
+  // AFAIK there's no way to check the empty elements, since you can't QI them.
+}
+
+function test_clear()
+{
+  var arr = create_n_element_array(5);
+  // just a sanity check
+  do_check_eq(5, arr.length);
+  arr.clear();
+  do_check_eq(0, arr.length);
+}
+
+function test_enumerate()
+{
+  var arr = create_n_element_array(5);
+  do_check_eq(5, arr.length);
+  var en = arr.enumerate();
+  var i = 0;
+  while (en.hasMoreElements()) {
+    let str = en.getNext();
+    do_check_true(str instanceof Ci.nsISupportsString);
+    do_check_eq(str.data, "element " + i);
+    i++;
+  }
+  do_check_eq(arr.length, i);
+}
+
+function test_nssupportsarray_interop() {
+  // Tests to check that an nsSupportsArray instance can behave like an
+  // nsIArray.
+  let test = Components.classes["@mozilla.org/supports-array;1"]
+             .createInstance(Ci.nsISupportsArray);
+
+  let str = new SupportsString();
+  str.data = "element";
+  test.AppendElement(str);
+
+  // Now query to an nsIArray.
+  let iarray = test.QueryInterface(Ci.nsIArray);
+  do_check_neq(iarray, null);
+
+  // Make sure |nsIArray.length| works.
+  do_check_eq(iarray.length, 1);
+
+  // Make sure |nsIArray.queryElementAt| works.
+  let elm = iarray.queryElementAt(0, Ci.nsISupportsString);
+  do_check_eq(elm.data, "element");
+
+  // Make sure |nsIArray.indexOf| works.
+  let idx = iarray.indexOf(0, str);
+  do_check_eq(idx, 0);
+
+  // Make sure |nsIArray.enumerate| works.
+  let en = iarray.enumerate();
+  do_check_neq(en, null);
+  let i = 0;
+  while (en.hasMoreElements()) {
+    let str = en.getNext();
+    do_check_true(str instanceof Ci.nsISupportsString);
+    do_check_eq(str.data, "element");
+    i++;
+  }
+
+  do_check_eq(iarray.length, i);
+}
+
+function test_nsiarrayextensions() {
+  // Tests to check that the extensions that make an nsArray act like an
+  // nsISupportsArray for iteration purposes works.
+  // Note: we do not want to QI here, just want to make sure the magic glue
+  // works as a drop-in replacement.
+
+  let fake_nsisupports_array = create_n_element_array(5);
+
+  // Check that |Count| works.
+  do_check_eq(5, fake_nsisupports_array.Count());
+
+  for (let i = 0; i < fake_nsisupports_array.Count(); i++) {
+    // Check that the generic |GetElementAt| works.
+    let elm = fake_nsisupports_array.GetElementAt(i);
+    do_check_neq(elm, null);
+    let str = elm.QueryInterface(Ci.nsISupportsString);
+    do_check_neq(str, null);
+    do_check_eq(str.data, "element " + i);
+  }
+}
+
+var tests = [
+  test_appending_null_actually_inserts,
+  test_object_gets_appended,
+  test_insert_at_beginning,
+  test_replace_element,
+  test_clear,
+  test_enumerate,
+  test_nssupportsarray_interop,
+  test_nsiarrayextensions,
+];
+
+function run_test() {
+  for (var i = 0; i < tests.length; i++)
+    tests[i]();
+}
diff --git a/xpcom/tests/unit/test_nsIProcess.js b/xpcom/tests/unit/test_nsIProcess.js
new file mode 100644
index 000000000..6c6a5a683
--- /dev/null
+++ b/xpcom/tests/unit/test_nsIProcess.js
@@ -0,0 +1,185 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+// nsIProcess unit test
+const TEST_ARGS = ["mozilla", "firefox", "thunderbird", "seamonkey", "foo",
+                   "bar", "argument with spaces", "\"argument with quotes\""];
+
+const TEST_UNICODE_ARGS = ["M\u00F8z\u00EEll\u00E5",
+                           "\u041C\u043E\u0437\u0438\u043B\u043B\u0430",
+                           "\u09AE\u09CB\u099C\u09BF\u09B2\u09BE",
+                           "\uD808\uDE2C\uD808\uDF63\uD808\uDDB7"];
+
+// test if a process can be started, polled for its running status
+// and then killed
+function test_kill()
+{
+  var file = get_test_program("TestBlockingProcess");
+ 
+  var process = Components.classes["@mozilla.org/process/util;1"]
+                          .createInstance(Components.interfaces.nsIProcess);
+  process.init(file);
+
+  do_check_false(process.isRunning);
+
+  try {
+    process.kill();
+    do_throw("Attempting to kill a not-running process should throw");
+  }
+  catch (e) { }
+
+  process.run(false, [], 0);
+
+  do_check_true(process.isRunning);
+
+  process.kill();
+
+  do_check_false(process.isRunning);
+
+  try {
+    process.kill();
+    do_throw("Attempting to kill a not-running process should throw");
+  }
+  catch (e) { }
+}
+
+// test if we can get an exit value from an application that is
+// guaranteed to return an exit value of 42
+function test_quick()
+{
+  var file = get_test_program("TestQuickReturn");
+  
+  var process = Components.classes["@mozilla.org/process/util;1"]
+                          .createInstance(Components.interfaces.nsIProcess);
+  process.init(file);
+  
+  // to get an exit value it must be a blocking process
+  process.run(true, [], 0);
+
+  do_check_eq(process.exitValue, 42);
+}
+
+function test_args(file, args, argsAreASCII)
+{
+  var process = Components.classes["@mozilla.org/process/util;1"]
+                          .createInstance(Components.interfaces.nsIProcess);
+  process.init(file);
+
+  if (argsAreASCII)  
+    process.run(true, args, args.length);
+  else  
+    process.runw(true, args, args.length);
+  
+  do_check_eq(process.exitValue, 0);
+}
+
+// test if an argument can be successfully passed to an application
+// that will return 0 if "mozilla" is the only argument
+function test_arguments()
+{
+  test_args(get_test_program("TestArguments"), TEST_ARGS, true);
+}
+
+// test if Unicode arguments can be successfully passed to an application
+function test_unicode_arguments()
+{
+  test_args(get_test_program("TestUnicodeArguments"), TEST_UNICODE_ARGS, false);
+}
+
+function rename_and_test(asciiName, unicodeName, args, argsAreASCII)
+{
+  var asciiFile = get_test_program(asciiName);
+  var asciiLeaf = asciiFile.leafName;
+  var unicodeLeaf = asciiLeaf.replace(asciiName, unicodeName);
+
+  asciiFile.moveTo(null, unicodeLeaf);
+
+  var unicodeFile = get_test_program(unicodeName);
+
+  test_args(unicodeFile, args, argsAreASCII);
+
+  unicodeFile.moveTo(null, asciiLeaf);
+}
+
+// test passing ASCII and Unicode arguments to an application with a Unicode name
+function test_unicode_app()
+{
+  rename_and_test("TestArguments",
+                  // "Unicode" in Tamil
+                  "\u0BAF\u0BC1\u0BA9\u0BBF\u0B95\u0BCB\u0B9F\u0BCD",
+                  TEST_ARGS, true);
+
+  rename_and_test("TestUnicodeArguments",
+                  // "Unicode" in Thai
+                  "\u0E22\u0E39\u0E19\u0E34\u0E42\u0E04\u0E14",
+                  TEST_UNICODE_ARGS, false);
+}
+
+// test if we get notified about a blocking process
+function test_notify_blocking()
+{
+  var file = get_test_program("TestQuickReturn");
+
+  var process = Components.classes["@mozilla.org/process/util;1"]
+                          .createInstance(Components.interfaces.nsIProcess);
+  process.init(file);
+
+  process.runAsync([], 0, {
+    observe: function(subject, topic, data) {
+      process = subject.QueryInterface(Components.interfaces.nsIProcess);
+      do_check_eq(topic, "process-finished");
+      do_check_eq(process.exitValue, 42);
+      test_notify_nonblocking();
+    }
+  });
+}
+
+// test if we get notified about a non-blocking process
+function test_notify_nonblocking()
+{
+  var file = get_test_program("TestArguments");
+
+  var process = Components.classes["@mozilla.org/process/util;1"]
+                          .createInstance(Components.interfaces.nsIProcess);
+  process.init(file);
+
+  process.runAsync(TEST_ARGS, TEST_ARGS.length, {
+    observe: function(subject, topic, data) {
+      process = subject.QueryInterface(Components.interfaces.nsIProcess);
+      do_check_eq(topic, "process-finished");
+      do_check_eq(process.exitValue, 0);
+      test_notify_killed();
+    }
+  });
+}
+
+// test if we get notified about a killed process
+function test_notify_killed()
+{
+  var file = get_test_program("TestBlockingProcess");
+
+  var process = Components.classes["@mozilla.org/process/util;1"]
+                          .createInstance(Components.interfaces.nsIProcess);
+  process.init(file);
+
+  process.runAsync([], 0, {
+    observe: function(subject, topic, data) {
+      process = subject.QueryInterface(Components.interfaces.nsIProcess);
+      do_check_eq(topic, "process-finished");
+      do_test_finished();
+    }
+  });
+
+  process.kill();
+}
+
+function run_test() {
+  set_process_running_environment();
+  test_kill();
+  test_quick();
+  test_arguments();
+  test_unicode_arguments();
+  test_unicode_app();
+  do_test_pending();
+  test_notify_blocking();
+}
diff --git a/xpcom/tests/unit/test_nsIProcess_stress.js b/xpcom/tests/unit/test_nsIProcess_stress.js
new file mode 100644
index 000000000..63799141d
--- /dev/null
+++ b/xpcom/tests/unit/test_nsIProcess_stress.js
@@ -0,0 +1,27 @@
+function run_test() {
+  set_process_running_environment();
+
+  var file = get_test_program("TestQuickReturn");
+  var thread = Components.classes["@mozilla.org/thread-manager;1"]
+                         .getService().currentThread;
+
+  for (var i = 0; i < 1000; i++) {
+    var process = Components.classes["@mozilla.org/process/util;1"]
+                          .createInstance(Components.interfaces.nsIProcess);
+    process.init(file);
+
+    process.run(false, [], 0);
+
+    try {
+      process.kill();
+    }
+    catch (e) { }
+
+    // We need to ensure that we process any events on the main thread -
+    // this allow threads to clean up properly and avoid out of memory
+    // errors during the test.
+    while (thread.hasPendingEvents())
+      thread.processNextEvent(false);
+  }
+
+}
\ No newline at end of file
diff --git a/xpcom/tests/unit/test_pipe.js b/xpcom/tests/unit/test_pipe.js
new file mode 100644
index 000000000..c16b33ab0
--- /dev/null
+++ b/xpcom/tests/unit/test_pipe.js
@@ -0,0 +1,63 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+var Cr = Components.results;
+var CC = Components.Constructor;
+
+var Pipe = CC("@mozilla.org/pipe;1", "nsIPipe", "init");
+
+function run_test()
+{
+  test_not_initialized();
+  test_ends_are_threadsafe();
+}
+
+function test_not_initialized()
+{
+  var p = Cc["@mozilla.org/pipe;1"]
+            .createInstance(Ci.nsIPipe);
+  try
+  {
+    var dummy = p.outputStream;
+    throw Cr.NS_ERROR_FAILURE;
+  }
+  catch (e)
+  {
+    if (e.result != Cr.NS_ERROR_NOT_INITIALIZED)
+      do_throw("using a pipe before initializing it should throw NS_ERROR_NOT_INITIALIZED");
+  }
+}
+
+function test_ends_are_threadsafe()
+{
+  var p, is, os;
+
+  p = new Pipe(true, true, 1024, 1, null);
+  is = p.inputStream.QueryInterface(Ci.nsIClassInfo);
+  os = p.outputStream.QueryInterface(Ci.nsIClassInfo);
+  do_check_true(Boolean(is.flags & Ci.nsIClassInfo.THREADSAFE));
+  do_check_true(Boolean(os.flags & Ci.nsIClassInfo.THREADSAFE));
+
+  p = new Pipe(true, false, 1024, 1, null);
+  is = p.inputStream.QueryInterface(Ci.nsIClassInfo);
+  os = p.outputStream.QueryInterface(Ci.nsIClassInfo);
+  do_check_true(Boolean(is.flags & Ci.nsIClassInfo.THREADSAFE));
+  do_check_true(Boolean(os.flags & Ci.nsIClassInfo.THREADSAFE));
+
+  p = new Pipe(false, true, 1024, 1, null);
+  is = p.inputStream.QueryInterface(Ci.nsIClassInfo);
+  os = p.outputStream.QueryInterface(Ci.nsIClassInfo);
+  do_check_true(Boolean(is.flags & Ci.nsIClassInfo.THREADSAFE));
+  do_check_true(Boolean(os.flags & Ci.nsIClassInfo.THREADSAFE));
+
+  p = new Pipe(false, false, 1024, 1, null);
+  is = p.inputStream.QueryInterface(Ci.nsIClassInfo);
+  os = p.outputStream.QueryInterface(Ci.nsIClassInfo);
+  do_check_true(Boolean(is.flags & Ci.nsIClassInfo.THREADSAFE));
+  do_check_true(Boolean(os.flags & Ci.nsIClassInfo.THREADSAFE));
+}
diff --git a/xpcom/tests/unit/test_process_directives.js b/xpcom/tests/unit/test_process_directives.js
new file mode 100644
index 000000000..807246f46
--- /dev/null
+++ b/xpcom/tests/unit/test_process_directives.js
@@ -0,0 +1,25 @@
+var Ci = Components.interfaces;
+var Cc = Components.classes;
+
+Components.utils.import("resource:///modules/Services.jsm");
+
+function run_test()
+{
+  Components.manager.autoRegister(do_get_file("data/process_directive.manifest"));
+
+  let isChild = Services.appinfo.processType == Services.appinfo.PROCESS_TYPE_CONTENT;
+
+  if (isChild) {
+    do_check_false("@mozilla.org/xpcom/tests/MainProcessDirectiveTest;1" in Cc);
+  } else {
+    let svc = Cc["@mozilla.org/xpcom/tests/MainProcessDirectiveTest;1"].createInstance(Ci.nsISupportsString);
+    do_check_eq(svc.data, "main process");
+  }
+
+  if (!isChild) {
+    do_check_false("@mozilla.org/xpcom/tests/ChildProcessDirectiveTest;1" in Cc);
+  } else {
+    let svc = Cc["@mozilla.org/xpcom/tests/ChildProcessDirectiveTest;1"].createInstance(Ci.nsISupportsString);
+    do_check_eq(svc.data, "child process");
+  }
+}
diff --git a/xpcom/tests/unit/test_process_directives_child.js b/xpcom/tests/unit/test_process_directives_child.js
new file mode 100644
index 000000000..dca63b356
--- /dev/null
+++ b/xpcom/tests/unit/test_process_directives_child.js
@@ -0,0 +1,3 @@
+function run_test() {
+  run_test_in_child("test_process_directives.js");
+}
diff --git a/xpcom/tests/unit/test_seek_multiplex.js b/xpcom/tests/unit/test_seek_multiplex.js
new file mode 100644
index 000000000..31232d134
--- /dev/null
+++ b/xpcom/tests/unit/test_seek_multiplex.js
@@ -0,0 +1,173 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+var Ci = Components.interfaces;
+var Cr = Components.results;
+var CC = Components.Constructor;
+var Cc = Components.classes;
+
+// The string we use as data.
+const data = "0123456789";
+// Number of streams in the multiplex stream.
+const count = 10;
+
+function test_multiplex_streams() {
+  var MultiplexStream = CC("@mozilla.org/io/multiplex-input-stream;1",
+                           "nsIMultiplexInputStream");
+  do_check_eq(1, 1);
+
+  var BinaryInputStream = Components.Constructor("@mozilla.org/binaryinputstream;1",
+                                                 "nsIBinaryInputStream");
+  var BinaryOutputStream = Components.Constructor("@mozilla.org/binaryoutputstream;1",
+                                                  "nsIBinaryOutputStream",
+                                                  "setOutputStream");
+  var multiplex = new MultiplexStream();
+  for (var i = 0; i < count; ++i) {
+    let s = Cc["@mozilla.org/io/string-input-stream;1"]
+              .createInstance(Ci.nsIStringInputStream);
+    s.setData(data, data.length);
+
+    multiplex.appendStream(s);
+  }
+  var seekable = multiplex.QueryInterface(Ci.nsISeekableStream);
+  var sis = Cc["@mozilla.org/scriptableinputstream;1"]
+              .createInstance(Ci.nsIScriptableInputStream);
+  sis.init(seekable);
+  // Read some data.
+  var readData = sis.read(20);
+  do_check_eq(readData, data + data);
+  // -- Tests for NS_SEEK_SET
+  // Seek to a non-zero, non-stream-boundary offset.
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_SET, 2);
+  do_check_eq(seekable.tell(), 2);
+  do_check_eq(seekable.available(), 98);
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_SET, 9);
+  do_check_eq(seekable.tell(), 9);
+  do_check_eq(seekable.available(), 91);
+  // Seek across stream boundary.
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_SET, 35);
+  do_check_eq(seekable.tell(), 35);
+  do_check_eq(seekable.available(), 65);
+  readData = sis.read(5);
+  do_check_eq(readData, data.slice(5));
+  do_check_eq(seekable.available(), 60);
+  // Seek at stream boundaries.
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_SET, 40);
+  do_check_eq(seekable.tell(), 40);
+  do_check_eq(seekable.available(), 60);
+  readData = sis.read(10);
+  do_check_eq(readData, data);
+  do_check_eq(seekable.tell(), 50);
+  do_check_eq(seekable.available(), 50);
+  // Rewind and read across streams.
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_SET, 39);
+  do_check_eq(seekable.tell(), 39);
+  do_check_eq(seekable.available(), 61);
+  readData = sis.read(11);
+  do_check_eq(readData, data.slice(9) + data);
+  do_check_eq(seekable.tell(), 50);
+  do_check_eq(seekable.available(), 50);
+  // Rewind to the beginning.
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_SET, 0);
+  do_check_eq(seekable.tell(), 0);
+  do_check_eq(seekable.available(), 100);
+  // Seek to some random location
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_SET, 50);
+  // -- Tests for NS_SEEK_CUR
+  // Positive seek.
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_CUR, 15);
+  do_check_eq(seekable.tell(), 65);
+  do_check_eq(seekable.available(), 35);
+  readData = sis.read(10);
+  do_check_eq(readData, data.slice(5) + data.slice(0, 5));
+  do_check_eq(seekable.tell(), 75);
+  do_check_eq(seekable.available(), 25);
+  // Negative seek.
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_CUR, -15);
+  do_check_eq(seekable.tell(), 60);
+  do_check_eq(seekable.available(), 40);
+  readData = sis.read(10);
+  do_check_eq(readData, data);
+  do_check_eq(seekable.tell(), 70);
+  do_check_eq(seekable.available(), 30);
+
+  // -- Tests for NS_SEEK_END
+  // Normal read.
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_END, -5);
+  do_check_eq(seekable.tell(), data.length * count - 5);
+  readData = sis.read(5);
+  do_check_eq(readData, data.slice(5));
+  do_check_eq(seekable.tell(), data.length * count);
+  // Read across streams.
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_END, -15);
+  do_check_eq(seekable.tell(), data.length * count - 15);
+  readData = sis.read(15);
+  do_check_eq(readData, data.slice(5) + data);
+  do_check_eq(seekable.tell(), data.length * count);
+
+  // -- Try to do various edge cases
+  // Forward seek from the end, should throw.
+  var caught = false;
+  try {
+    seekable.seek(Ci.nsISeekableStream.NS_SEEK_END, 15);
+  } catch(e) {
+    caught = true;
+  }
+  do_check_eq(caught, true);
+  do_check_eq(seekable.tell(), data.length * count);
+  // Backward seek from the beginning, should be clamped.
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_SET, 0);
+  do_check_eq(seekable.tell(), 0);
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_CUR, -15);
+  do_check_eq(seekable.tell(), 0);
+  // Seek too far: should be clamped.
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_SET, 0);
+  do_check_eq(seekable.tell(), 0);
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_CUR, 3 * data.length * count);
+  do_check_eq(seekable.tell(), 100);
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_SET, data.length * count);
+  do_check_eq(seekable.tell(), 100);
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_CUR, -2 * data.length * count);
+  do_check_eq(seekable.tell(), 0);
+}
+
+function test_multiplex_bug797871() {
+
+  var data = "1234567890123456789012345678901234567890";
+
+  var MultiplexStream = CC("@mozilla.org/io/multiplex-input-stream;1",
+                           "nsIMultiplexInputStream");
+  do_check_eq(1, 1);
+
+  var BinaryInputStream = Components.Constructor("@mozilla.org/binaryinputstream;1",
+                                                 "nsIBinaryInputStream");
+  var BinaryOutputStream = Components.Constructor("@mozilla.org/binaryoutputstream;1",
+                                                  "nsIBinaryOutputStream",
+                                                  "setOutputStream");
+  var multiplex = new MultiplexStream();
+  let s = Cc["@mozilla.org/io/string-input-stream;1"]
+            .createInstance(Ci.nsIStringInputStream);
+  s.setData(data, data.length);
+
+  multiplex.appendStream(s);
+
+  var seekable = multiplex.QueryInterface(Ci.nsISeekableStream);
+  var sis = Cc["@mozilla.org/scriptableinputstream;1"]
+              .createInstance(Ci.nsIScriptableInputStream);
+  sis.init(seekable);
+
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_SET, 8);
+  do_check_eq(seekable.tell(), 8);
+  readData = sis.read(2);
+  do_check_eq(seekable.tell(), 10);
+
+  seekable.seek(Ci.nsISeekableStream.NS_SEEK_SET, 20);
+  do_check_eq(seekable.tell(), 20);
+}
+
+function run_test() {
+  test_multiplex_streams();
+  test_multiplex_bug797871();
+}
+
diff --git a/xpcom/tests/unit/test_storagestream.js b/xpcom/tests/unit/test_storagestream.js
new file mode 100644
index 000000000..33fdc2202
--- /dev/null
+++ b/xpcom/tests/unit/test_storagestream.js
@@ -0,0 +1,162 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+var Cr = Components.results;
+
+function run_test()
+{
+  test1();
+  test2();
+  test3();
+  test4();
+}
+
+/**
+ * Checks that getting an input stream from a storage stream which has never had
+ * anything written to it throws a not-initialized exception.
+ */
+function test1()
+{
+  var ss = Cc["@mozilla.org/storagestream;1"]
+             .createInstance(Ci.nsIStorageStream);
+  ss.init(1024, 1024, null);
+
+  var out = ss.getOutputStream(0);
+  var inp2 = ss.newInputStream(0);
+  do_check_eq(inp2.available(), 0);
+  do_check_true(inp2.isNonBlocking());
+
+  var sis =
+      Cc["@mozilla.org/scriptableinputstream;1"]
+        .createInstance(Ci.nsIScriptableInputStream);
+  sis.init(inp2);
+
+  var threw = false;
+  try {
+    sis.read(1);
+  } catch (ex if ex.result == Cr.NS_BASE_STREAM_WOULD_BLOCK) {
+    threw = true;
+  }
+  do_check_true(threw);
+}
+
+/**
+ * Checks that getting an input stream from a storage stream to which 0 bytes of
+ * data have been explicitly written doesn't throw an exception.
+ */
+function test2()
+{
+  var ss = Cc["@mozilla.org/storagestream;1"]
+             .createInstance(Ci.nsIStorageStream);
+  ss.init(1024, 1024, null);
+
+  var out = ss.getOutputStream(0);
+  out.write("", 0);
+  try
+  {
+    var inp2 = ss.newInputStream(0);
+  }
+  catch (e)
+  {
+    do_throw("shouldn't throw exception when new input stream created");
+  }
+}
+
+/**
+ * Checks that reading any non-zero amount of data from a storage stream
+ * which has had 0 bytes written to it explicitly works correctly.
+ */
+function test3()
+{
+  var ss = Cc["@mozilla.org/storagestream;1"]
+             .createInstance(Ci.nsIStorageStream);
+  ss.init(1024, 1024, null);
+
+  var out = ss.getOutputStream(0);
+  out.write("", 0);
+  try
+  {
+    var inp = ss.newInputStream(0);
+  }
+  catch (e)
+  {
+    do_throw("newInputStream(0) shouldn't throw if write() is called: " + e);
+  }
+
+  do_check_true(inp.isNonBlocking(), "next test expects a non-blocking stream");
+
+  try
+  {
+    var threw = false;
+    var bis = BIS(inp);
+    var dummy = bis.readByteArray(5);
+  }
+  catch (e)
+  {
+    if (e.result != Cr.NS_BASE_STREAM_WOULD_BLOCK)
+      do_throw("wrong error thrown: " + e);
+    threw = true;
+  }
+  do_check_true(threw,
+                "should have thrown (nsStorageInputStream is nonblocking)");
+}
+
+/**
+ * Basic functionality test for storagestream: write data to it, get an input
+ * stream, and read the data back to see that it matches.
+ */
+function test4()
+{
+  var bytes = [65, 66, 67, 68, 69, 70, 71, 72, 73, 74];
+
+  var ss = Cc["@mozilla.org/storagestream;1"]
+             .createInstance(Ci.nsIStorageStream);
+  ss.init(1024, 1024, null);
+
+  var outStream = ss.getOutputStream(0);
+
+  var bos = Cc["@mozilla.org/binaryoutputstream;1"]
+              .createInstance(Ci.nsIBinaryOutputStream);
+  bos.setOutputStream(outStream);
+
+  bos.writeByteArray(bytes, bytes.length);
+  bos.close();
+
+  var inp = ss.newInputStream(0);
+  var bis = BIS(inp);
+
+  var count = 0;
+  while (count < bytes.length)
+  {
+    var data = bis.read8(1);
+    do_check_eq(data, bytes[count++]);
+  }
+
+  var threw = false;
+  try
+  {
+    data = bis.read8(1);
+  }
+  catch (e)
+  {
+    if (e.result != Cr.NS_ERROR_FAILURE)
+      do_throw("wrong error thrown: " + e);
+    threw = true;
+  }
+  if (!threw)
+    do_throw("should have thrown but instead returned: '" + data + "'");
+}
+
+
+function BIS(input)
+{
+  var bis = Cc["@mozilla.org/binaryinputstream;1"]
+              .createInstance(Ci.nsIBinaryInputStream);
+  bis.setInputStream(input);
+  return bis;
+}
diff --git a/xpcom/tests/unit/test_streams.js b/xpcom/tests/unit/test_streams.js
new file mode 100644
index 000000000..e668cb8d5
--- /dev/null
+++ b/xpcom/tests/unit/test_streams.js
@@ -0,0 +1,157 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+var Ci = Components.interfaces;
+var Cr = Components.results;
+var CC = Components.Constructor;
+
+var Pipe = CC("@mozilla.org/pipe;1",
+              "nsIPipe",
+              "init");
+var BinaryOutput = CC("@mozilla.org/binaryoutputstream;1",
+                      "nsIBinaryOutputStream",
+                      "setOutputStream");
+var BinaryInput = CC("@mozilla.org/binaryinputstream;1",
+                     "nsIBinaryInputStream",
+                     "setInputStream");
+
+/**
+ * Binary stream tests.
+ */
+function test_binary_streams() {
+  var p, is, os;
+
+  p = new Pipe(false, false, 1024, 1, null);
+  is = new BinaryInput(p.inputStream);
+  os = new BinaryOutput(p.outputStream);
+
+  const LargeNum = Math.pow(2, 18) + Math.pow(2, 12) + 1;
+  const HugeNum = Math.pow(2, 62);
+  const HelloStr = "Hello World";
+  const HelloArray = Array.map(HelloStr, function(c) {return c.charCodeAt(0)});
+  var countObj = {};
+  var msg = {};
+  var buffer = new ArrayBuffer(HelloArray.length);
+
+  // Test reading immediately after writing.
+  os.writeBoolean(true);
+  do_check_eq(is.readBoolean(), true);
+  os.write8(4);
+  do_check_eq(is.read8(), 4);
+  os.write16(4);
+  do_check_eq(is.read16(), 4);
+  os.write16(1024);
+  do_check_eq(is.read16(), 1024);
+  os.write32(7);
+  do_check_eq(is.read32(), 7);
+  os.write32(LargeNum);
+  do_check_eq(is.read32(), LargeNum);
+  os.write64(LargeNum);
+  do_check_eq(is.read64(), LargeNum);
+  os.write64(1024);
+  do_check_eq(is.read64(), 1024);
+  os.write64(HugeNum);
+  do_check_eq(is.read64(), HugeNum);
+  os.writeFloat(2.5);
+  do_check_eq(is.readFloat(), 2.5);
+//  os.writeDouble(Math.SQRT2);
+//  do_check_eq(is.readDouble(), Math.SQRT2);
+  os.writeStringZ("Mozilla");
+  do_check_eq(is.readCString(), "Mozilla");
+  os.writeWStringZ("Gecko");
+  do_check_eq(is.readString(), "Gecko");
+  os.writeBytes(HelloStr, HelloStr.length);
+  do_check_eq(is.available(), HelloStr.length);
+  msg = is.readBytes(HelloStr.length);
+  do_check_eq(msg, HelloStr);
+  msg = null;
+  countObj.value = -1;
+  os.writeByteArray(HelloArray, HelloArray.length);
+  do_check_eq(is.available(), HelloStr.length);
+  msg = is.readByteArray(HelloStr.length)
+  do_check_eq(typeof msg, typeof HelloArray);
+  do_check_eq(msg.toSource(), HelloArray.toSource());
+  do_check_eq(is.available(), 0);
+  os.writeByteArray(HelloArray, HelloArray.length);
+  do_check_eq(is.readArrayBuffer(buffer.byteLength, buffer), HelloArray.length);
+  do_check_eq([...(new Uint8Array(buffer))].toSource(), HelloArray.toSource());
+  do_check_eq(is.available(), 0);
+
+  // Test writing in one big chunk.
+  os.writeBoolean(true);
+  os.write8(4);
+  os.write16(4);
+  os.write16(1024);
+  os.write32(7);
+  os.write32(LargeNum);
+  os.write64(LargeNum);
+  os.write64(1024);
+  os.write64(HugeNum);
+  os.writeFloat(2.5);
+//  os.writeDouble(Math.SQRT2);
+  os.writeStringZ("Mozilla");
+  os.writeWStringZ("Gecko");
+  os.writeBytes(HelloStr, HelloStr.length);
+  os.writeByteArray(HelloArray, HelloArray.length);
+  // Available should not be zero after a long write like this.
+  do_check_neq(is.available(), 0);
+
+  // Test reading in one big chunk.
+  do_check_eq(is.readBoolean(), true);
+  do_check_eq(is.read8(), 4);
+  do_check_eq(is.read16(), 4);
+  do_check_eq(is.read16(), 1024);
+  do_check_eq(is.read32(), 7);
+  do_check_eq(is.read32(), LargeNum);
+  do_check_eq(is.read64(), LargeNum);
+  do_check_eq(is.read64(), 1024);
+  do_check_eq(is.read64(), HugeNum);
+  do_check_eq(is.readFloat(), 2.5);
+//  do_check_eq(is.readDouble(), Math.SQRT2);
+  do_check_eq(is.readCString(), "Mozilla");
+  do_check_eq(is.readString(), "Gecko");
+  // Remember, we wrote HelloStr twice - once as a string, and then as an array.
+  do_check_eq(is.available(), HelloStr.length * 2);
+  msg = is.readBytes(HelloStr.length);
+  do_check_eq(msg, HelloStr);
+  msg = null;
+  countObj.value = -1;
+  do_check_eq(is.available(), HelloStr.length);
+  msg = is.readByteArray(HelloStr.length)
+  do_check_eq(typeof msg, typeof HelloArray);
+  do_check_eq(msg.toSource(), HelloArray.toSource());
+  do_check_eq(is.available(), 0);
+  
+  // Test for invalid actions.
+  os.close();
+  is.close();
+
+  try {
+    os.writeBoolean(false);
+    do_throw("Not reached!");
+  } catch (e if (e instanceof Ci.nsIException &&
+                 e.result == Cr.NS_BASE_STREAM_CLOSED)) {
+    // do nothing
+  }
+
+  try {
+    is.available();
+    do_throw("Not reached!");
+  } catch (e if (e instanceof Ci.nsIException &&
+                 e.result == Cr.NS_BASE_STREAM_CLOSED)) {
+    // do nothing
+  }
+
+  try {
+    is.readBoolean();
+    do_throw("Not reached!");
+  } catch (e if (e instanceof Ci.nsIException &&
+                 e.result == Cr.NS_ERROR_FAILURE)) {
+    // do nothing
+  }
+}
+
+function run_test() {
+  test_binary_streams();
+}
diff --git a/xpcom/tests/unit/test_stringstream.js b/xpcom/tests/unit/test_stringstream.js
new file mode 100644
index 000000000..60503a58f
--- /dev/null
+++ b/xpcom/tests/unit/test_stringstream.js
@@ -0,0 +1,23 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+var Cr = Components.results;
+
+function run_test()
+{
+    var s = Cc["@mozilla.org/io/string-input-stream;1"]
+              .createInstance(Ci.nsIStringInputStream);
+    var body = "This is a test";
+    s.setData(body, body.length);
+    do_check_eq(s.available(), body.length);
+
+    var sis = Cc["@mozilla.org/scriptableinputstream;1"]
+                .createInstance(Ci.nsIScriptableInputStream);
+    sis.init(s);
+
+    do_check_eq(sis.read(body.length), body);
+}
diff --git a/xpcom/tests/unit/test_symlinks.js b/xpcom/tests/unit/test_symlinks.js
new file mode 100644
index 000000000..a615af8d5
--- /dev/null
+++ b/xpcom/tests/unit/test_symlinks.js
@@ -0,0 +1,144 @@
+const CWD = do_get_cwd();
+
+const DIR_TARGET     = "target";
+const DIR_LINK       = "link";
+const DIR_LINK_LINK  = "link_link";
+const FILE_TARGET    = "target.txt";
+const FILE_LINK      = "link.txt";
+const FILE_LINK_LINK = "link_link.txt";
+
+const DOES_NOT_EXIST = "doesnotexist";
+const DANGLING_LINK  = "dangling_link";
+const LOOP_LINK      = "loop_link";
+
+const nsIFile = Components.interfaces.nsIFile;
+
+var process;
+function createSymLink(from, to) {
+  if (!process) {
+    var ln = Components.classes["@mozilla.org/file/local;1"]
+                       .createInstance(Components.interfaces.nsILocalFile);
+    ln.initWithPath("/bin/ln");
+
+    process = Components.classes["@mozilla.org/process/util;1"]
+                        .createInstance(Components.interfaces.nsIProcess);
+    process.init(ln);
+  }
+
+  const args = ["-s", from, to];
+  process.run(true, args, args.length);
+  do_check_eq(process.exitValue, 0);
+}
+
+function makeSymLink(from, toName, relative) {
+  var to = from.parent;
+  to.append(toName);
+
+  if (relative) {
+    createSymLink(from.leafName, to.path);
+  }
+  else {
+    createSymLink(from.path, to.path);
+  }
+
+  do_check_true(to.isSymlink());
+
+  print("---");
+  print(from.path);
+  print(to.path);
+  print(to.target);
+
+  if (from.leafName != DOES_NOT_EXIST && from.isSymlink()) {
+    // XXXjag wish I could set followLinks to false so we'd just get
+    // the symlink's direct target instead of the final target.
+    do_check_eq(from.target, to.target);
+  }
+  else {
+    do_check_eq(from.path, to.target);
+  }
+
+  return to;
+}
+
+function setupTestDir(testDir, relative) {
+  var targetDir = testDir.clone();
+  targetDir.append(DIR_TARGET);
+
+  if (testDir.exists()) {
+    testDir.remove(true);
+  }
+  do_check_true(!testDir.exists());
+
+  testDir.create(nsIFile.DIRECTORY_TYPE, 0o777);
+
+  targetDir.create(nsIFile.DIRECTORY_TYPE, 0o777);
+
+  var targetFile = testDir.clone();
+  targetFile.append(FILE_TARGET);
+  targetFile.create(nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  var imaginary = testDir.clone();
+  imaginary.append(DOES_NOT_EXIST);
+
+  var loop = testDir.clone();
+  loop.append(LOOP_LINK);
+
+  var dirLink  = makeSymLink(targetDir, DIR_LINK, relative);
+  var fileLink = makeSymLink(targetFile, FILE_LINK, relative);
+
+  makeSymLink(dirLink, DIR_LINK_LINK, relative);
+  makeSymLink(fileLink, FILE_LINK_LINK, relative);
+
+  makeSymLink(imaginary, DANGLING_LINK, relative);
+
+  try {
+    makeSymLink(loop, LOOP_LINK, relative);
+    do_check_true(false);
+  }
+  catch (e) {
+  }
+}
+
+function createSpaces(dirs, files, links) {
+  function longest(a, b) {
+    return a.length > b.length ? a : b;
+  }
+  return dirs.concat(files, links).reduce(longest, "").replace(/./g, " ");
+}
+
+function testSymLinks(testDir, relative) {
+  setupTestDir(testDir, relative);
+
+  const dirLinks   = [DIR_LINK, DIR_LINK_LINK];
+  const fileLinks  = [FILE_LINK, FILE_LINK_LINK];
+  const otherLinks = [DANGLING_LINK, LOOP_LINK];
+  const dirs  = [DIR_TARGET].concat(dirLinks);
+  const files = [FILE_TARGET].concat(fileLinks);
+  const links = otherLinks.concat(dirLinks, fileLinks);
+
+  const spaces = createSpaces(dirs, files, links);
+  const bools = {false: " false", true: " true "};
+  print(spaces + " dir   file  symlink");
+  var dirEntries = testDir.directoryEntries;
+  while (dirEntries.hasMoreElements()) {
+    const file = dirEntries.getNext().QueryInterface(nsIFile);
+    const name = file.leafName;
+    print(name + spaces.substring(name.length) + bools[file.isDirectory()] +
+          bools[file.isFile()] + bools[file.isSymlink()]);
+    do_check_eq(file.isDirectory(), dirs.indexOf(name) != -1);
+    do_check_eq(file.isFile(), files.indexOf(name) != -1);
+    do_check_eq(file.isSymlink(), links.indexOf(name) != -1);
+  }
+}
+
+function run_test() {
+  // Skip this test on Windows
+  if (mozinfo.os == "win")
+    return;
+
+  var testDir = CWD;
+  testDir.append("test_symlinks");
+
+  testSymLinks(testDir, false);
+  testSymLinks(testDir, true);
+}
diff --git a/xpcom/tests/unit/test_systemInfo.js b/xpcom/tests/unit/test_systemInfo.js
new file mode 100644
index 000000000..58fa8042c
--- /dev/null
+++ b/xpcom/tests/unit/test_systemInfo.js
@@ -0,0 +1,20 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+function run_test() {
+  const PROPERTIES = ["name", "host", "arch", "version", "pagesize",
+                      "pageshift", "memmapalign", "cpucount", "memsize"];
+  let sysInfo = Components.classes["@mozilla.org/system-info;1"].
+                getService(Components.interfaces.nsIPropertyBag2);
+
+  PROPERTIES.forEach(function(aPropertyName) {
+    print("Testing property: " + aPropertyName);
+    let value = sysInfo.getProperty(aPropertyName);
+    do_check_true(!!value);
+  });
+
+  // This property must exist, but its value might be zero.
+  print("Testing property: umask")
+  do_check_eq(typeof sysInfo.getProperty("umask"), "number");
+}
diff --git a/xpcom/tests/unit/test_versioncomparator.js b/xpcom/tests/unit/test_versioncomparator.js
new file mode 100644
index 000000000..35f8f6eee
--- /dev/null
+++ b/xpcom/tests/unit/test_versioncomparator.js
@@ -0,0 +1,59 @@
+// Versions to test listed in ascending order, none can be equal
+var comparisons = [
+  "0.9",
+  "0.9.1",
+  "1.0pre1",
+  "1.0pre2",
+  "1.0",
+  "1.1pre",
+  "1.1pre1a",
+  "1.1pre1",
+  "1.1pre10a",
+  "1.1pre10",
+  "1.1",
+  "1.1.0.1",
+  "1.1.1",
+  "1.1.*",
+  "1.*",
+  "2.0",
+  "2.1",
+  "3.0.-1",
+  "3.0"
+];
+
+// Every version in this list means the same version number
+var equality = [
+  "1.1pre",
+  "1.1pre0",
+  "1.0+"
+];
+
+function run_test()
+{
+  var vc = Components.classes["@mozilla.org/xpcom/version-comparator;1"]
+                     .getService(Components.interfaces.nsIVersionComparator);
+
+  for (var i = 0; i < comparisons.length; i++) {
+    for (var j = 0; j < comparisons.length; j++) {
+      var result = vc.compare(comparisons[i], comparisons[j]);
+      if (i == j) {
+        if (result != 0)
+          do_throw(comparisons[i] + " should be the same as itself");
+      }
+      else if (i < j) {
+        if (!(result < 0))
+          do_throw(comparisons[i] + " should be less than " + comparisons[j]);
+      }
+      else if (!(result > 0)) {
+        do_throw(comparisons[i] + " should be greater than " + comparisons[j]);
+      }
+    }
+  }
+
+  for (i = 0; i < equality.length; i++) {
+    for (j = 0; j < equality.length; j++) {
+      if (vc.compare(equality[i], equality[j]) != 0)
+        do_throw(equality[i] + " should equal " + equality[j]);
+    }
+  }
+}
diff --git a/xpcom/tests/unit/test_windows_cmdline_file.js b/xpcom/tests/unit/test_windows_cmdline_file.js
new file mode 100644
index 000000000..4a3a6cc5f
--- /dev/null
+++ b/xpcom/tests/unit/test_windows_cmdline_file.js
@@ -0,0 +1,21 @@
+let { classes: Cc, interfaces: Ci, results: Cr, utils: Cu } = Components;
+Cu.import("resource://gre/modules/Services.jsm");
+
+let executableFile = Services.dirsvc.get("CurProcD", Ci.nsIFile);
+executableFile.append("xpcshell.exe");
+function run_test() {
+  let quote = '"'; // Windows' cmd processor doesn't actually use single quotes.
+  for (let suffix of ["", " -osint", ` --blah "%PROGRAMFILES%"`]) {
+    let cmdline = quote + executableFile.path + quote + suffix;
+    do_print(`Testing with ${cmdline}`);
+    let f = Cc["@mozilla.org/file/local;1"].createInstance(Ci.nsILocalFileWin);
+    f.initWithCommandLine(cmdline);
+    Assert.equal(f.path, executableFile.path, "Should be able to recover executable path");
+  }
+
+  let f = Cc["@mozilla.org/file/local;1"].createInstance(Ci.nsILocalFileWin);
+  f.initWithCommandLine("%ComSpec% -c echo 'hi'");
+  let cmd = Services.dirsvc.get("SysD", Ci.nsIFile);
+  cmd.append("cmd.exe");
+  Assert.equal(f.path, cmd.path, "Should be able to replace env vars.");
+}
diff --git a/xpcom/tests/unit/test_windows_registry.js b/xpcom/tests/unit/test_windows_registry.js
new file mode 100644
index 000000000..9a17678f8
--- /dev/null
+++ b/xpcom/tests/unit/test_windows_registry.js
@@ -0,0 +1,205 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et: */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const Cr = Components.results;
+const Ci = Components.interfaces;
+const Cc = Components.classes;
+const Cu = Components.utils;
+const CC = Components.Constructor;
+
+const nsIWindowsRegKey = Ci.nsIWindowsRegKey;
+let regKeyComponent = Cc["@mozilla.org/windows-registry-key;1"];
+
+function run_test()
+{
+    //* create a key structure in a spot that's normally writable (somewhere under HKCU). 
+    let testKey = regKeyComponent.createInstance(nsIWindowsRegKey);
+
+    // If it's already present because a previous test crashed or didn't clean up properly, clean it up first.
+    let keyName = BASE_PATH + "\\" + TESTDATA_KEYNAME;
+    setup_test_run(testKey, keyName);
+
+    //* test that the write* functions write stuff
+    test_writing_functions(testKey);
+
+    //* check that the valueCount/getValueName functions work for the values we just wrote
+    test_value_functions(testKey);
+    
+    //* check that the get* functions work for the values we just wrote.
+    test_reading_functions(testKey);
+    
+    //* check that the get* functions fail with the right exception codes if we ask for the wrong type or if the value name doesn't exist at all
+    test_invalidread_functions(testKey);
+
+    //* check that creating/enumerating/deleting child keys works
+    test_childkey_functions(testKey);
+
+    test_watching_functions(testKey);
+
+    //* clean up
+    cleanup_test_run(testKey, keyName);
+}
+
+function setup_test_run(testKey, keyName)
+{
+    do_print("Setup test run");
+    try {
+        testKey.open(nsIWindowsRegKey.ROOT_KEY_CURRENT_USER, keyName, nsIWindowsRegKey.ACCESS_READ);
+        do_print("Test key exists. Needs cleanup.");
+        cleanup_test_run(testKey, keyName);
+    }
+    catch (e if (e instanceof Ci.nsIException && e.result == Cr.NS_ERROR_FAILURE))
+    {
+    }
+
+    testKey.create(nsIWindowsRegKey.ROOT_KEY_CURRENT_USER, keyName, nsIWindowsRegKey.ACCESS_ALL);
+}
+
+function test_writing_functions(testKey)
+{
+    strictEqual(testKey.valueCount, 0);
+
+    strictEqual(testKey.hasValue(TESTDATA_STRNAME), false);
+    testKey.writeStringValue(TESTDATA_STRNAME, TESTDATA_STRVALUE);
+    strictEqual(testKey.hasValue(TESTDATA_STRNAME), true);
+
+    strictEqual(testKey.hasValue(TESTDATA_INTNAME), false);
+    testKey.writeIntValue(TESTDATA_INTNAME, TESTDATA_INTVALUE);
+
+    strictEqual(testKey.hasValue(TESTDATA_INT64NAME), false);
+    testKey.writeInt64Value(TESTDATA_INT64NAME, TESTDATA_INT64VALUE);
+
+    strictEqual(testKey.hasValue(TESTDATA_BINARYNAME), false);
+    testKey.writeBinaryValue(TESTDATA_BINARYNAME, TESTDATA_BINARYVALUE);
+}
+
+function test_value_functions(testKey)
+{
+    strictEqual(testKey.valueCount, 4);
+    strictEqual(testKey.getValueName(0), TESTDATA_STRNAME);
+    strictEqual(testKey.getValueName(1), TESTDATA_INTNAME);
+    strictEqual(testKey.getValueName(2), TESTDATA_INT64NAME);
+    strictEqual(testKey.getValueName(3), TESTDATA_BINARYNAME);
+}
+
+function test_reading_functions(testKey)
+{
+    strictEqual(testKey.getValueType(TESTDATA_STRNAME), nsIWindowsRegKey.TYPE_STRING);
+    strictEqual(testKey.readStringValue(TESTDATA_STRNAME), TESTDATA_STRVALUE);
+
+    strictEqual(testKey.getValueType(TESTDATA_INTNAME), nsIWindowsRegKey.TYPE_INT);
+    strictEqual(testKey.readIntValue(TESTDATA_INTNAME), TESTDATA_INTVALUE);
+   
+    strictEqual(testKey.getValueType(TESTDATA_INT64NAME), nsIWindowsRegKey.TYPE_INT64);
+    strictEqual( testKey.readInt64Value(TESTDATA_INT64NAME), TESTDATA_INT64VALUE);
+    
+    strictEqual(testKey.getValueType(TESTDATA_BINARYNAME), nsIWindowsRegKey.TYPE_BINARY);
+    strictEqual( testKey.readBinaryValue(TESTDATA_BINARYNAME), TESTDATA_BINARYVALUE);
+}
+
+function test_invalidread_functions(testKey)
+{
+    try {
+        testKey.readIntValue(TESTDATA_STRNAME);
+        do_throw("Reading an integer from a string registry value should throw.");
+    } catch (e if (e instanceof Ci.nsIException && e.result == Cr.NS_ERROR_FAILURE)) {
+    }
+
+    try {
+        let val = testKey.readStringValue(TESTDATA_INTNAME);
+        do_throw("Reading an string from an Int registry value should throw." + val);
+    } catch (e if (e instanceof Ci.nsIException && e.result == Cr.NS_ERROR_FAILURE)) {
+    }
+
+    try {
+        testKey.readStringValue(TESTDATA_INT64NAME);
+        do_throw("Reading an string from an Int64 registry value should throw.");
+    } catch (e if (e instanceof Ci.nsIException && e.result == Cr.NS_ERROR_FAILURE)) {
+    }
+
+    try {
+        testKey.readStringValue(TESTDATA_BINARYNAME);
+        do_throw("Reading a string from an Binary registry value should throw.");
+    } catch (e if (e instanceof Ci.nsIException && e.result == Cr.NS_ERROR_FAILURE)) {
+    }
+
+}
+
+function test_childkey_functions(testKey)
+{
+    strictEqual(testKey.childCount, 0);
+    strictEqual(testKey.hasChild(TESTDATA_CHILD_KEY), false);
+    
+    let childKey = testKey.createChild(TESTDATA_CHILD_KEY, nsIWindowsRegKey.ACCESS_ALL);
+    childKey.close();
+
+    strictEqual(testKey.childCount, 1);
+    strictEqual(testKey.hasChild(TESTDATA_CHILD_KEY), true);
+    strictEqual(testKey.getChildName(0), TESTDATA_CHILD_KEY);
+
+    childKey = testKey.openChild(TESTDATA_CHILD_KEY, nsIWindowsRegKey.ACCESS_ALL);
+    testKey.removeChild(TESTDATA_CHILD_KEY);
+    strictEqual(testKey.childCount, 0);
+    strictEqual(testKey.hasChild(TESTDATA_CHILD_KEY), false);
+}
+
+function test_watching_functions(testKey)
+{
+    strictEqual(testKey.isWatching(), false);
+    strictEqual(testKey.hasChanged(), false);
+    
+    testKey.startWatching(true);
+    strictEqual(testKey.isWatching(), true);
+    
+    testKey.stopWatching();
+    strictEqual(testKey.isWatching(), false);
+
+    // Create a child key, and update a value
+    let childKey = testKey.createChild(TESTDATA_CHILD_KEY, nsIWindowsRegKey.ACCESS_ALL);
+    childKey.writeIntValue(TESTDATA_INTNAME, TESTDATA_INTVALUE);
+
+    // Start a recursive watch, and update the child's value
+    testKey.startWatching(true);
+    strictEqual(testKey.isWatching(), true);
+
+    childKey.writeIntValue(TESTDATA_INTNAME, 0);
+    strictEqual(testKey.hasChanged(), true);
+    testKey.stopWatching();
+    strictEqual(testKey.isWatching(), false);
+        
+    childKey.removeValue(TESTDATA_INTNAME);
+    childKey.close();
+    testKey.removeChild(TESTDATA_CHILD_KEY);
+}
+
+function cleanup_test_run(testKey, keyName)
+{
+    do_print("Cleaning up test.");
+
+    for (var i = 0; i < testKey.childCount; i++) {
+        testKey.removeChild(testKey.getChildName(i));
+    }
+    testKey.close();
+
+    let baseKey = regKeyComponent.createInstance(nsIWindowsRegKey);
+    baseKey.open(nsIWindowsRegKey.ROOT_KEY_CURRENT_USER, BASE_PATH, nsIWindowsRegKey.ACCESS_ALL);
+    baseKey.removeChild(TESTDATA_KEYNAME);
+    baseKey.close();
+}
+
+// Test data used above.
+const BASE_PATH = "SOFTWARE";
+const TESTDATA_KEYNAME = "TestRegXPC";
+const TESTDATA_STRNAME = "AString";
+const TESTDATA_STRVALUE = "The quick brown fox jumps over the lazy dog.";
+const TESTDATA_INTNAME = "AnInteger";
+const TESTDATA_INTVALUE = 65536;
+const TESTDATA_INT64NAME = "AnInt64";
+const TESTDATA_INT64VALUE = 9223372036854775807;
+const TESTDATA_BINARYNAME = "ABinary";
+const TESTDATA_BINARYVALUE = "She sells seashells by the seashore";
+const TESTDATA_CHILD_KEY = "TestChildKey";
diff --git a/xpcom/tests/unit/test_windows_shortcut.js b/xpcom/tests/unit/test_windows_shortcut.js
new file mode 100644
index 000000000..42cb023ff
--- /dev/null
+++ b/xpcom/tests/unit/test_windows_shortcut.js
@@ -0,0 +1,279 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et: */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+var Cr = Components.results;
+var Ci = Components.interfaces;
+var Cc = Components.classes;
+var Cu = Components.utils;
+var CC = Components.Constructor;
+
+const LocalFile = CC("@mozilla.org/file/local;1", "nsILocalFile", "initWithPath");
+
+Cu.import("resource://gre/modules/Services.jsm");
+
+function run_test()
+{
+  // This test makes sense only on Windows, so skip it on other platforms
+  if ("nsILocalFileWin" in Ci
+   && do_get_cwd() instanceof Ci.nsILocalFileWin) {
+
+    let tempDir = Services.dirsvc.get("TmpD", Ci.nsILocalFile);
+    tempDir.append("shortcutTesting");
+    tempDir.createUnique(Ci.nsIFile.DIRECTORY_TYPE, 0o666);
+
+    test_create_noargs(tempDir);
+    test_create_notarget(tempDir);
+    test_create_targetonly(tempDir);
+    test_create_normal(tempDir);
+    test_create_unicode(tempDir);
+
+    test_update_noargs(tempDir);
+    test_update_notarget(tempDir);
+    test_update_targetonly(tempDir);
+    test_update_normal(tempDir);
+    test_update_unicode(tempDir);
+  }
+}
+
+function test_create_noargs(tempDir)
+{
+  let shortcutFile = tempDir.clone();
+  shortcutFile.append("shouldNeverExist.lnk");
+  shortcutFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  let win = shortcutFile.QueryInterface(Ci.nsILocalFileWin);
+
+  try
+  {
+    win.setShortcut();
+    do_throw("Creating a shortcut with no args (no target) should throw");
+  }
+  catch(e if (e instanceof Ci.nsIException
+             && e.result == Cr.NS_ERROR_FILE_TARGET_DOES_NOT_EXIST))
+  {
+
+  }
+}
+
+function test_create_notarget(tempDir)
+{
+  let shortcutFile = tempDir.clone();
+  shortcutFile.append("shouldNeverExist2.lnk");
+  shortcutFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  let win = shortcutFile.QueryInterface(Ci.nsILocalFileWin);
+
+  try
+  {
+    win.setShortcut(null,
+                    do_get_cwd(),
+                    "arg1 arg2",
+                    "Shortcut with no target");
+    do_throw("Creating a shortcut with no target should throw");
+  }
+  catch(e if (e instanceof Ci.nsIException
+             && e.result == Cr.NS_ERROR_FILE_TARGET_DOES_NOT_EXIST))
+  {
+
+  }
+}
+
+function test_create_targetonly(tempDir)
+{
+  let shortcutFile = tempDir.clone();
+  shortcutFile.append("createdShortcut.lnk");
+  shortcutFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  let targetFile = tempDir.clone();
+  targetFile.append("shortcutTarget.exe");
+  targetFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  let win = shortcutFile.QueryInterface(Ci.nsILocalFileWin);
+
+  win.setShortcut(targetFile);
+
+  let shortcutTarget = LocalFile(shortcutFile.target);
+  do_check_true(shortcutTarget.equals(targetFile));
+}
+
+function test_create_normal(tempDir)
+{
+  let shortcutFile = tempDir.clone();
+  shortcutFile.append("createdShortcut.lnk");
+  shortcutFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  let targetFile = tempDir.clone();
+  targetFile.append("shortcutTarget.exe");
+  targetFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  let win = shortcutFile.QueryInterface(Ci.nsILocalFileWin);
+
+  win.setShortcut(targetFile,
+                  do_get_cwd(),
+                  "arg1 arg2",
+                  "Ordinary shortcut");
+
+  let shortcutTarget = LocalFile(shortcutFile.target);
+  do_check_true(shortcutTarget.equals(targetFile))
+}
+
+function test_create_unicode(tempDir)
+{
+  let shortcutFile = tempDir.clone();
+  shortcutFile.append("createdShortcut.lnk");
+  shortcutFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  let targetFile = tempDir.clone();
+  targetFile.append("ṩhогТϾừ†Target.exe");
+  targetFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  let win = shortcutFile.QueryInterface(Ci.nsILocalFileWin);
+
+  win.setShortcut(targetFile,
+                  do_get_cwd(), // XXX: This should probably be a unicode dir
+                  "ᾶṟǵ1 ᾶṟǵ2",
+                  "ῧṋіḉѻₑ");
+
+  let shortcutTarget = LocalFile(shortcutFile.target);
+  do_check_true(shortcutTarget.equals(targetFile))
+}
+
+function test_update_noargs(tempDir)
+{
+  let shortcutFile = tempDir.clone();
+  shortcutFile.append("createdShortcut.lnk");
+  shortcutFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  let targetFile = tempDir.clone();
+  targetFile.append("shortcutTarget.exe");
+  targetFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  let win = shortcutFile.QueryInterface(Ci.nsILocalFileWin);
+
+  win.setShortcut(targetFile,
+                  do_get_cwd(),
+                  "arg1 arg2",
+                  "A sample shortcut");
+
+  win.setShortcut();
+
+  let shortcutTarget = LocalFile(shortcutFile.target);
+  do_check_true(shortcutTarget.equals(targetFile))
+}
+
+function test_update_notarget(tempDir)
+{
+  let shortcutFile = tempDir.clone();
+  shortcutFile.append("createdShortcut.lnk");
+  shortcutFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  let targetFile = tempDir.clone();
+  targetFile.append("shortcutTarget.exe");
+  targetFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  let win = shortcutFile.QueryInterface(Ci.nsILocalFileWin);
+
+  win.setShortcut(targetFile,
+                  do_get_cwd(),
+                  "arg1 arg2",
+                  "A sample shortcut");
+
+  win.setShortcut(null,
+                  do_get_profile(),
+                  "arg3 arg4",
+                  "An UPDATED shortcut");
+
+  let shortcutTarget = LocalFile(shortcutFile.target);
+  do_check_true(shortcutTarget.equals(targetFile))
+}
+
+function test_update_targetonly(tempDir)
+{
+  let shortcutFile = tempDir.clone();
+  shortcutFile.append("createdShortcut.lnk");
+  shortcutFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  let targetFile = tempDir.clone();
+  targetFile.append("shortcutTarget.exe");
+  targetFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  let win = shortcutFile.QueryInterface(Ci.nsILocalFileWin);
+
+  win.setShortcut(targetFile,
+                  do_get_cwd(),
+                  "arg1 arg2",
+                  "A sample shortcut");
+
+  let newTargetFile = tempDir.clone();
+  newTargetFile.append("shortcutTarget.exe");
+  shortcutFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  win.setShortcut(newTargetFile);
+
+  let shortcutTarget = LocalFile(shortcutFile.target);
+  do_check_true(shortcutTarget.equals(newTargetFile))
+}
+
+function test_update_normal(tempDir)
+{
+  let shortcutFile = tempDir.clone();
+  shortcutFile.append("createdShortcut.lnk");
+  shortcutFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  let targetFile = tempDir.clone();
+  targetFile.append("shortcutTarget.exe");
+  targetFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  let win = shortcutFile.QueryInterface(Ci.nsILocalFileWin);
+
+  win.setShortcut(targetFile,
+                  do_get_cwd(),
+                  "arg1 arg2",
+                  "A sample shortcut");
+
+  let newTargetFile = tempDir.clone();
+  newTargetFile.append("shortcutTarget.exe");
+  newTargetFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  win.setShortcut(newTargetFile,
+                  do_get_profile(),
+                  "arg3 arg4",
+                  "An UPDATED shortcut");
+
+  let shortcutTarget = LocalFile(shortcutFile.target);
+  do_check_true(shortcutTarget.equals(newTargetFile))
+}
+
+function test_update_unicode(tempDir)
+{
+  let shortcutFile = tempDir.clone();
+  shortcutFile.append("createdShortcut.lnk");
+  shortcutFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  let targetFile = tempDir.clone();
+  targetFile.append("shortcutTarget.exe");
+  targetFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  let win = shortcutFile.QueryInterface(Ci.nsILocalFileWin);
+
+  win.setShortcut(targetFile,
+                  do_get_cwd(),
+                  "arg1 arg2",
+                  "A sample shortcut");
+
+  let newTargetFile = tempDir.clone();
+  newTargetFile.append("ṩhогТϾừ†Target.exe");
+  shortcutFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
+
+  win.setShortcut(newTargetFile,
+                  do_get_profile(), // XXX: This should probably be unicode
+                  "ᾶṟǵ3 ᾶṟǵ4",
+                  "A ῧṋіḉѻₑ shortcut");
+
+  let shortcutTarget = LocalFile(shortcutFile.target);
+  do_check_true(shortcutTarget.equals(newTargetFile))
+}
diff --git a/xpcom/tests/unit/xpcomtest.manifest b/xpcom/tests/unit/xpcomtest.manifest
new file mode 100644
index 000000000..43a4931c6
--- /dev/null
+++ b/xpcom/tests/unit/xpcomtest.manifest
@@ -0,0 +1 @@
+interfaces xpcomtest.xpt
diff --git a/xpcom/tests/unit/xpcshell.ini b/xpcom/tests/unit/xpcshell.ini
new file mode 100644
index 000000000..cf8d93627
--- /dev/null
+++ b/xpcom/tests/unit/xpcshell.ini
@@ -0,0 +1,79 @@
+[DEFAULT]
+head = head_xpcom.js
+tail =
+support-files =
+  bug725015.manifest
+  compmgr_warnings.manifest
+  data/**
+  xpcomtest.xpt
+  xpcomtest.manifest
+generated-files =
+  xpcomtest.xpt
+
+[test_bug121341.js]
+[test_bug325418.js]
+[test_bug332389.js]
+[test_bug333505.js]
+[test_bug364285-1.js]
+# Bug 902073: test fails consistently on Android x86
+skip-if = os == "android"
+[test_bug374754.js]
+[test_bug476919.js]
+# Bug 676998: test fails consistently on Android
+fail-if = os == "android"
+[test_bug478086.js]
+[test_bug656331.js]
+# Bug 676998: test fails consistently on Android
+fail-if = os == "android"
+[test_bug725015.js]
+[test_debugger_malloc_size_of.js]
+[test_compmgr_warnings.js]
+# Bug 676998: test fails consistently on Android
+fail-if = os == "android"
+[test_file_createUnique.js]
+[test_file_equality.js]
+[test_hidden_files.js]
+[test_home.js]
+# Bug 676998: test fails consistently on Android
+fail-if = os == "android"
+[test_iniProcessor.js]
+[test_ioutil.js]
+[test_localfile.js]
+[test_mac_bundle.js]
+[test_nsIMutableArray.js]
+[test_nsIProcess.js]
+skip-if = os == "win" || os == "linux" # bug 582821, bug 1325609
+# Bug 676998: test fails consistently on Android
+fail-if = os == "android"
+[test_nsIProcess_stress.js]
+skip-if = os == "win" # bug 676412, test isn't needed on windows and runs really slowly
+[test_pipe.js]
+[test_process_directives.js]
+skip-if = os == "android"
+[test_process_directives_child.js]
+skip-if = os == "android"
+[test_storagestream.js]
+[test_streams.js]
+[test_seek_multiplex.js]
+[test_stringstream.js]
+[test_symlinks.js]
+# Bug 676998: test fails consistently on Android
+fail-if = os == "android"
+[test_systemInfo.js]
+# Bug 902081: test fails consistently on Android 2.2, passes on 4.0
+skip-if = os == "android"
+[test_versioncomparator.js]
+[test_comp_no_aslr.js]
+skip-if = os != "win"
+[test_windows_shortcut.js]
+skip-if = os != "win"
+[test_windows_cmdline_file.js]
+skip-if = os != "win"
+[test_bug745466.js]
+skip-if = os == "win"
+# Bug 676998: test fails consistently on Android
+fail-if = os == "android"
+[test_file_renameTo.js]
+[test_notxpcom_scriptable.js]
+[test_windows_registry.js]
+skip-if = os != "win"
diff --git a/xpcom/tests/windows/TestCOM.cpp b/xpcom/tests/windows/TestCOM.cpp
new file mode 100644
index 000000000..9f0b9854c
--- /dev/null
+++ b/xpcom/tests/windows/TestCOM.cpp
@@ -0,0 +1,158 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <windows.h>
+#include <unknwn.h>
+#include <stdio.h>
+#include "nsISupports.h"
+#include "nsIFactory.h"
+
+// unknwn.h is needed to build with WIN32_LEAN_AND_MEAN
+#include <unknwn.h>
+
+#include "gtest/gtest.h"
+
+// {5846BA30-B856-11d1-A98A-00805F8A7AC4}
+#define NS_ITEST_COM_IID \
+{ 0x5846ba30, 0xb856, 0x11d1, \
+  { 0xa9, 0x8a, 0x0, 0x80, 0x5f, 0x8a, 0x7a, 0xc4 } }
+
+class nsITestCom: public nsISupports
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_ITEST_COM_IID)
+  NS_IMETHOD Test() = 0;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsITestCom, NS_ITEST_COM_IID)
+
+/*
+ * nsTestCom
+ */
+
+class nsTestCom final : public nsITestCom {
+  NS_DECL_ISUPPORTS
+
+public:
+  nsTestCom() {
+  }
+
+  NS_IMETHOD Test() {
+    return NS_OK;
+  }
+
+  static int sDestructions;
+
+private:
+  ~nsTestCom() {
+    sDestructions++;
+  }
+};
+
+int nsTestCom::sDestructions;
+
+NS_IMPL_QUERY_INTERFACE(nsTestCom, nsITestCom)
+
+MozExternalRefCountType nsTestCom::AddRef()
+{
+  nsrefcnt res = ++mRefCnt;
+  NS_LOG_ADDREF(this, mRefCnt, "nsTestCom", sizeof(*this));
+  return res;
+}
+
+MozExternalRefCountType nsTestCom::Release()
+{
+  nsrefcnt res = --mRefCnt;
+  NS_LOG_RELEASE(this, mRefCnt, "nsTestCom");
+  if (res == 0) {
+    delete this;
+  }
+  return res;
+}
+
+class nsTestComFactory final : public nsIFactory {
+  ~nsTestComFactory() { sDestructions++; }
+  NS_DECL_ISUPPORTS
+public:
+  nsTestComFactory() {
+  }
+
+  NS_IMETHOD CreateInstance(nsISupports *aOuter,
+                            const nsIID &aIID,
+                            void **aResult);
+
+  NS_IMETHOD LockFactory(bool aLock) {
+    return NS_OK;
+  }
+
+  static int sDestructions;
+};
+
+int nsTestComFactory::sDestructions;
+
+NS_IMPL_ISUPPORTS(nsTestComFactory, nsIFactory)
+
+nsresult nsTestComFactory::CreateInstance(nsISupports *aOuter,
+					  const nsIID &aIID,
+					  void **aResult)
+{
+  if (aOuter != nullptr) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+
+  nsTestCom *t = new nsTestCom();
+
+  if (t == nullptr) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  NS_ADDREF(t);
+  nsresult res = t->QueryInterface(aIID, aResult);
+  NS_RELEASE(t);
+
+  return res;
+}
+
+TEST(TestCOM, WindowsInterop)
+{
+  nsTestComFactory *inst = new nsTestComFactory();
+
+  // Test we can QI nsIFactory to an IClassFactory.
+  IClassFactory *iFactory = nullptr;
+  nsresult rv = inst->QueryInterface(NS_GET_IID(nsIFactory),
+                                      (void **) &iFactory);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+  ASSERT_TRUE(iFactory);
+
+  // Test we can CreateInstance with an IUnknown.
+  IUnknown *iUnknown = nullptr;
+
+  HRESULT hr = iFactory->LockServer(TRUE);
+  ASSERT_TRUE(SUCCEEDED(hr));
+  hr = iFactory->CreateInstance(nullptr, IID_IUnknown, (void **) &iUnknown);
+  ASSERT_TRUE(SUCCEEDED(hr));
+  ASSERT_TRUE(iUnknown);
+  hr = iFactory->LockServer(FALSE);
+  ASSERT_TRUE(SUCCEEDED(hr));
+
+  // Test we can QI an IUnknown to nsITestCom.
+  nsITestCom *iTestCom = nullptr;
+  GUID testGUID = NS_ITEST_COM_IID;
+  hr = iUnknown->QueryInterface(testGUID,
+				 (void **) &iTestCom);
+  ASSERT_TRUE(SUCCEEDED(hr));
+  ASSERT_TRUE(iTestCom);
+
+  // Make sure we can call our test function (and the pointer is valid).
+  rv = iTestCom->Test();
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  iUnknown->Release();
+  iTestCom->Release();
+  iFactory->Release();
+
+  ASSERT_EQ(nsTestComFactory::sDestructions, 1);
+  ASSERT_EQ(nsTestCom::sDestructions, 1);
+}
diff --git a/xpcom/tests/windows/TestHelloXPLoop.cpp b/xpcom/tests/windows/TestHelloXPLoop.cpp
new file mode 100644
index 000000000..ffb4442e0
--- /dev/null
+++ b/xpcom/tests/windows/TestHelloXPLoop.cpp
@@ -0,0 +1,144 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIServiceManager.h"
+#include "nsCOMPtr.h"
+#include "nsCNativeApp.h"
+#include "nsIEventLoop.h"
+#include <windows.h>
+
+static NS_DEFINE_CID(kNativeAppCID, NS_NATIVE_APP_CID);
+
+LRESULT CALLBACK WndProc(HWND wnd, UINT msg, WPARAM wParam, LPARAM lParam);
+
+void ErrorBox(LPSTR text)
+{
+	MessageBox(nullptr, text, "XP Event Loop", MB_OK | MB_ICONSTOP);
+}
+
+void InfoBox(LPSTR text)
+{
+	MessageBox(nullptr, text, "XP Event Loop", MB_OK | MB_ICONINFORMATION);
+}
+
+int WINAPI WinMain(HINSTANCE inst, 
+                   HINSTANCE prevInstance, 
+                   LPSTR lpszCmdLine,
+                   int nShowCmd)
+{
+	char* lpszAppName = "HelloWorld";
+	HWND wnd;
+	WNDCLASSEX wndclass;
+	int retCode;
+
+    {	//  Needed to scope all nsCOMPtr within XPCOM Init and Shutdown
+      nsresult rv;
+      nsCOMPtr<nsIServiceManager> servMan;
+      rv = NS_InitXPCOM2(getter_AddRefs(servMan), nullptr, nullptr);
+      if(NS_FAILED(rv))
+      {
+        ErrorBox("Failed to initialize xpcom.");
+        return -1;
+      }
+      
+      nsCOMPtr<nsIComponentRegistrar> registrar = do_QueryInterface(servMan);
+      NS_ASSERTION(registrar, "Null nsIComponentRegistrar");
+      registrar->AutoRegister(nullptr);
+      
+      nsCOMPtr<nsINativeApp> nativeAppService(do_GetService(kNativeAppCID, &rv));
+
+      if(NS_FAILED(rv))
+      {
+        ErrorBox("Failed to get nativeAppService");
+        return -1;
+      }
+      wndclass.cbSize        = sizeof(wndclass);
+      wndclass.style         = CS_HREDRAW | CS_VREDRAW;
+      wndclass.lpfnWndProc   = WndProc;
+      wndclass.cbClsExtra    = 0;
+      wndclass.cbWndExtra    = 0;
+      wndclass.hInstance     = inst;
+      wndclass.hIcon         = LoadIcon(nullptr, IDI_APPLICATION);
+      wndclass.hCursor       = LoadCursor(nullptr, IDC_ARROW);
+      wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
+      wndclass.lpszMenuName  = nullptr;
+      wndclass.lpszClassName = lpszAppName;
+      wndclass.hIconSm       = LoadIcon(nullptr, IDI_APPLICATION);
+
+      RegisterClassEx(&wndclass) ;
+      
+      wnd = CreateWindow(lpszAppName, "The Hello World",
+                         WS_OVERLAPPEDWINDOW,
+                         CW_USEDEFAULT, CW_USEDEFAULT,
+                         CW_USEDEFAULT, CW_USEDEFAULT,
+                         nullptr, nullptr, inst, nullptr);		     
+      
+      ShowWindow(wnd, nShowCmd);
+      UpdateWindow(wnd);
+      
+      nsCOMPtr<nsIEventLoop> eventLoop;
+      
+      if(NS_FAILED(nativeAppService->CreateEventLoop(L"_MainLoop", 
+                                                     nsEventLoopTypes::MainAppLoop, getter_AddRefs(eventLoop))))
+        {
+          ErrorBox("Failed to create event Loop");
+          return 0;
+        } 
+      
+      eventLoop->Run(nullptr, nullptr, nullptr, &retCode);
+      eventLoop = nullptr; // Clear out before Shutting down XPCOM
+      
+      InfoBox("Hello World app is out of loop");
+    }
+	NS_ShutdownXPCOM(nullptr);
+	InfoBox("Hello World app is exiting");
+	return retCode;
+}
+
+LRESULT CALLBACK WndProc(HWND wnd, UINT msg, WPARAM wParam, LPARAM lParam)
+{
+	HDC         hdc;
+	PAINTSTRUCT ps;
+	RECT        rect;
+
+	switch(msg)
+		{
+		case WM_PAINT:
+			hdc = BeginPaint(wnd, &ps);
+
+			GetClientRect(wnd, &rect);
+
+			DrawText(hdc, "Hello, XP Event Loop!", -1, &rect,
+					 DT_SINGLELINE | DT_CENTER | DT_VCENTER);
+
+			EndPaint(wnd, &ps);
+			return 0;
+
+		case WM_DESTROY:
+			{
+			nsresult rv;
+			nsCOMPtr<nsINativeApp> nativeAppService = 
+			         do_GetService(kNativeAppCID, &rv);
+			if(NS_FAILED(rv))
+				{
+				ErrorBox("Could not get NativeAppService");
+				return 0;
+				}
+			nsCOMPtr<nsIEventLoop> eventLoop;
+
+			if(NS_FAILED(nativeAppService->FindEventLoop(L"_MainLoop", 
+				getter_AddRefs(eventLoop))))
+				{
+				ErrorBox("Failed to find event Loop");
+				return 0;
+				}
+			eventLoop->Exit(0);
+			}
+			return 0;
+		}
+
+	return DefWindowProc(wnd, msg, wParam, lParam);
+}
diff --git a/xpcom/tests/windows/TestNTFSPermissions.cpp b/xpcom/tests/windows/TestNTFSPermissions.cpp
new file mode 100644
index 000000000..062a9e650
--- /dev/null
+++ b/xpcom/tests/windows/TestNTFSPermissions.cpp
@@ -0,0 +1,286 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Test for NTFS File Permissions being correctly changed to match the new
+ * directory upon moving a file.  (Bug 224692.)
+ */
+
+#include "../TestHarness.h"
+#include "nsEmbedString.h"
+#include "nsIFile.h"
+#include <windows.h>
+#include <aclapi.h>
+
+#define BUFFSIZE 512
+
+
+
+nsresult TestPermissions()
+{
+
+    nsresult rv; // Return value
+
+    // File variables
+    HANDLE tempFileHandle;
+    nsCOMPtr<nsIFile> tempFile;
+    nsCOMPtr<nsIFile> tempDirectory1;
+    nsCOMPtr<nsIFile> tempDirectory2;
+    WCHAR filePath[MAX_PATH];
+    WCHAR dir1Path[MAX_PATH];
+    WCHAR dir2Path[MAX_PATH];
+
+    // Security variables
+    DWORD result;
+    PSID everyoneSID = nullptr, adminSID = nullptr;
+    PACL dirACL = nullptr, fileACL = nullptr;
+    PSECURITY_DESCRIPTOR dirSD = nullptr, fileSD = nullptr;
+    EXPLICIT_ACCESS ea[2];
+    SID_IDENTIFIER_AUTHORITY SIDAuthWorld =
+            SECURITY_WORLD_SID_AUTHORITY;
+    SID_IDENTIFIER_AUTHORITY SIDAuthNT = SECURITY_NT_AUTHORITY;
+    SECURITY_ATTRIBUTES sa;
+    TRUSTEE everyoneTrustee;
+    ACCESS_MASK everyoneRights;
+
+    // Create a well-known SID for the Everyone group.
+    if(!AllocateAndInitializeSid(&SIDAuthWorld, 1,
+                     SECURITY_WORLD_RID,
+                     0, 0, 0, 0, 0, 0, 0,
+                     &everyoneSID))
+    {
+        fail("NTFS Permissions: AllocateAndInitializeSid Error");
+        return NS_ERROR_FAILURE;
+    }
+
+    // Create a SID for the Administrators group.
+    if(! AllocateAndInitializeSid(&SIDAuthNT, 2,
+                     SECURITY_BUILTIN_DOMAIN_RID,
+                     DOMAIN_ALIAS_RID_ADMINS,
+                     0, 0, 0, 0, 0, 0,
+                     &adminSID)) 
+    {
+        fail("NTFS Permissions: AllocateAndInitializeSid Error");
+        return NS_ERROR_FAILURE; 
+    }
+
+    // Initialize an EXPLICIT_ACCESS structure for an ACE.
+    // The ACE will allow Everyone read access to the directory.
+    ZeroMemory(&ea, 2 * sizeof(EXPLICIT_ACCESS));
+    ea[0].grfAccessPermissions = GENERIC_READ;
+    ea[0].grfAccessMode = SET_ACCESS;
+    ea[0].grfInheritance= SUB_CONTAINERS_AND_OBJECTS_INHERIT;
+    ea[0].Trustee.TrusteeForm = TRUSTEE_IS_SID;
+    ea[0].Trustee.TrusteeType = TRUSTEE_IS_WELL_KNOWN_GROUP;
+    ea[0].Trustee.ptstrName  = (LPTSTR) everyoneSID;
+
+    // Initialize an EXPLICIT_ACCESS structure for an ACE.
+    // The ACE will allow the Administrators group full access
+    ea[1].grfAccessPermissions = GENERIC_ALL | STANDARD_RIGHTS_ALL;
+    ea[1].grfAccessMode = SET_ACCESS;
+    ea[1].grfInheritance= SUB_CONTAINERS_AND_OBJECTS_INHERIT;
+    ea[1].Trustee.TrusteeForm = TRUSTEE_IS_SID;
+    ea[1].Trustee.TrusteeType = TRUSTEE_IS_GROUP;
+    ea[1].Trustee.ptstrName  = (LPTSTR) adminSID;
+
+    // Create a new ACL that contains the new ACEs.
+    result = SetEntriesInAcl(2, ea, nullptr, &dirACL);
+    if (ERROR_SUCCESS != result) 
+    {
+        fail("NTFS Permissions: SetEntriesInAcl Error");
+        return NS_ERROR_FAILURE; 
+    }
+
+    // Initialize a security descriptor.  
+    dirSD = (PSECURITY_DESCRIPTOR) LocalAlloc(LPTR, 
+                             SECURITY_DESCRIPTOR_MIN_LENGTH); 
+    if (nullptr == dirSD) 
+    { 
+        fail("NTFS Permissions: LocalAlloc Error");
+        return NS_ERROR_FAILURE; 
+    }
+
+    if (!InitializeSecurityDescriptor(dirSD,
+            SECURITY_DESCRIPTOR_REVISION)) 
+    {  
+        fail("NTFS Permissions: InitializeSecurityDescriptor Error");
+        return NS_ERROR_FAILURE; 
+    } 
+
+    // Add the ACL to the security descriptor. 
+    if (!SetSecurityDescriptorDacl(dirSD, true, dirACL, false)) 
+    {  
+        fail("NTFS Permissions: SetSecurityDescriptorDacl Error");
+        return NS_ERROR_FAILURE;  
+    } 
+
+    // Initialize a security attributes structure.
+    sa.nLength = sizeof (SECURITY_ATTRIBUTES);
+    sa.lpSecurityDescriptor = dirSD;
+    sa.bInheritHandle = false;
+
+    // Create and open first temporary directory
+    if(!CreateDirectoryW(L".\\NTFSPERMTEMP1", &sa))
+    {
+        fail("NTFS Permissions: Creating Temporary Directory");
+        return NS_ERROR_FAILURE;
+    }
+
+    GetFullPathNameW((LPCWSTR)L".\\NTFSPERMTEMP1", MAX_PATH, dir1Path,
+                     nullptr);
+
+    rv = NS_NewLocalFile(nsEmbedString(dir1Path), false,
+                         getter_AddRefs(tempDirectory1));
+    if (NS_FAILED(rv))
+    {
+        fail("NTFS Permissions: Opening Temporary Directory 1");
+        return rv;
+    }
+
+
+    // Create and open temporary file
+    tempFileHandle = CreateFileW(L".\\NTFSPERMTEMP1\\NTFSPerm.tmp", 
+                            GENERIC_READ | GENERIC_WRITE,
+                            0, 
+                            nullptr, //default security
+                            CREATE_ALWAYS,        
+                            FILE_ATTRIBUTE_NORMAL,
+                            nullptr);  
+
+    if(tempFileHandle == INVALID_HANDLE_VALUE)
+    {
+        fail("NTFS Permissions: Creating Temporary File");
+        return NS_ERROR_FAILURE;
+    }
+
+    CloseHandle(tempFileHandle);
+
+    GetFullPathNameW((LPCWSTR)L".\\NTFSPERMTEMP1\\NTFSPerm.tmp", 
+                        MAX_PATH, filePath, nullptr);
+
+    rv = NS_NewLocalFile(nsEmbedString(filePath), false,
+                         getter_AddRefs(tempFile));
+    if (NS_FAILED(rv))
+    {
+        fail("NTFS Permissions: Opening Temporary File");
+                return rv;
+    }
+
+    // Update Everyone Explict_Acess to full access.
+    ea[0].grfAccessPermissions = GENERIC_ALL | STANDARD_RIGHTS_ALL;
+
+    // Update the ACL to contain the new ACEs.
+    result = SetEntriesInAcl(2, ea, nullptr, &dirACL);
+    if (ERROR_SUCCESS != result) 
+    {
+        fail("NTFS Permissions: SetEntriesInAcl 2 Error");
+        return NS_ERROR_FAILURE; 
+    }
+
+    // Add the new ACL to the security descriptor. 
+    if (!SetSecurityDescriptorDacl(dirSD, true, dirACL, false)) 
+    {  
+        fail("NTFS Permissions: SetSecurityDescriptorDacl 2 Error");
+        return NS_ERROR_FAILURE;  
+    } 
+
+    // Create and open second temporary directory
+    if(!CreateDirectoryW(L".\\NTFSPERMTEMP2", &sa))
+    {
+        fail("NTFS Permissions: Creating Temporary Directory 2");
+        return NS_ERROR_FAILURE;
+    }
+
+    GetFullPathNameW((LPCWSTR)L".\\NTFSPERMTEMP2", MAX_PATH, dir2Path,
+                     nullptr);
+
+    rv = NS_NewLocalFile(nsEmbedString(dir2Path), false,
+                         getter_AddRefs(tempDirectory2));
+    if (NS_FAILED(rv))
+    {
+        fail("NTFS Permissions: Opening Temporary Directory 2");
+        return rv;
+    }
+
+    // Move the file.
+    rv = tempFile->MoveTo(tempDirectory2, EmptyString());
+
+    if (NS_FAILED(rv))
+    {
+        fail("NTFS Permissions: Moving");
+        return rv;
+    }
+
+    // Access the ACL of the file
+    result = GetNamedSecurityInfoW(L".\\NTFSPERMTEMP2\\NTFSPerm.tmp", 
+                                        SE_FILE_OBJECT,
+                                        DACL_SECURITY_INFORMATION | 
+                                        UNPROTECTED_DACL_SECURITY_INFORMATION,
+                                        nullptr, nullptr, &fileACL, nullptr,
+                                        &fileSD);
+    if (ERROR_SUCCESS != result) 
+    {
+        fail("NTFS Permissions: GetNamedSecurityDescriptor Error");
+        return NS_ERROR_FAILURE; 
+    }
+
+    // Build a trustee representing "Everyone"
+    BuildTrusteeWithSid(&everyoneTrustee, everyoneSID);
+
+    // Get Everyone's effective rights.
+    result = GetEffectiveRightsFromAcl(fileACL, &everyoneTrustee, 
+                                        &everyoneRights);
+    if (ERROR_SUCCESS != result) 
+    {
+        fail("NTFS Permissions: GetEffectiveRightsFromAcl Error");
+        return NS_ERROR_FAILURE; 
+    }
+
+    // Check for delete access, which we won't have unless permissions have 
+    // updated
+    if((everyoneRights & DELETE) == (DELETE))
+    {
+        passed("NTFS Permissions Test");
+        rv = NS_OK;
+    }
+    else
+    {
+        fail("NTFS Permissions: Access check.");
+        rv = NS_ERROR_FAILURE;
+    }
+
+    // Cleanup
+    if (everyoneSID) 
+        FreeSid(everyoneSID);
+    if (adminSID) 
+        FreeSid(adminSID);
+    if (dirACL) 
+        LocalFree(dirACL);
+    if (dirSD) 
+        LocalFree(dirSD);
+    if(fileACL)
+        LocalFree(fileACL);
+
+    tempDirectory1->Remove(true);
+    tempDirectory2->Remove(true);
+    
+    return rv;
+}
+
+int main(int argc, char** argv)
+{
+    ScopedXPCOM xpcom("NTFSPermissionsTests"); // name for tests being run
+    if (xpcom.failed())
+        return 1;
+
+    int rv = 0;
+
+    if(NS_FAILED(TestPermissions()))
+        rv = 1;
+
+    return rv;
+
+}
+
diff --git a/xpcom/tests/windows/TestNtPathToDosPath.cpp b/xpcom/tests/windows/TestNtPathToDosPath.cpp
new file mode 100644
index 000000000..b826d4f20
--- /dev/null
+++ b/xpcom/tests/windows/TestNtPathToDosPath.cpp
@@ -0,0 +1,193 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <windows.h>
+#include <winnetwk.h>
+
+#include "mozilla/FileUtilsWin.h"
+#include "mozilla/DebugOnly.h"
+#include "nsCRTGlue.h"
+
+#include "gtest/gtest.h"
+
+class DriveMapping
+{
+public:
+  DriveMapping(const nsAString& aRemoteUNCPath);
+  ~DriveMapping();
+
+  bool
+  Init();
+  bool
+  ChangeDriveLetter();
+  wchar_t
+  GetDriveLetter() { return mDriveLetter; }
+
+private:
+  bool
+  DoMapping();
+  void
+  Disconnect(wchar_t aDriveLetter);
+
+  wchar_t   mDriveLetter;
+  nsString  mRemoteUNCPath;
+};
+
+DriveMapping::DriveMapping(const nsAString& aRemoteUNCPath)
+  : mDriveLetter(0)
+  , mRemoteUNCPath(aRemoteUNCPath)
+{
+}
+
+bool
+DriveMapping::Init()
+{
+  if (mDriveLetter) {
+    return false;
+  }
+  return DoMapping();
+}
+
+bool
+DriveMapping::DoMapping()
+{
+  wchar_t drvTemplate[] = L" :";
+  NETRESOURCEW netRes = {0};
+  netRes.dwType = RESOURCETYPE_DISK;
+  netRes.lpLocalName = drvTemplate;
+  netRes.lpRemoteName = reinterpret_cast<wchar_t*>(mRemoteUNCPath.BeginWriting());
+  wchar_t driveLetter = L'D';
+  DWORD result = NO_ERROR;
+  do {
+    drvTemplate[0] = driveLetter;
+    result = WNetAddConnection2W(&netRes, nullptr, nullptr, CONNECT_TEMPORARY);
+  } while (result == ERROR_ALREADY_ASSIGNED && ++driveLetter <= L'Z');
+  if (result != NO_ERROR) {
+    return false;
+  }
+  mDriveLetter = driveLetter;
+  return true;
+}
+
+bool
+DriveMapping::ChangeDriveLetter()
+{
+  wchar_t prevDriveLetter = mDriveLetter;
+  bool result = DoMapping();
+  MOZ_RELEASE_ASSERT(mDriveLetter != prevDriveLetter);
+  if (result && prevDriveLetter) {
+    Disconnect(prevDriveLetter);
+  }
+  return result;
+}
+
+void
+DriveMapping::Disconnect(wchar_t aDriveLetter)
+{
+  wchar_t drvTemplate[] = {aDriveLetter, L':', L'\0'};
+  DWORD result = WNetCancelConnection2W(drvTemplate, 0, TRUE);
+  MOZ_RELEASE_ASSERT(result == NO_ERROR);
+}
+
+DriveMapping::~DriveMapping()
+{
+  if (mDriveLetter) {
+    Disconnect(mDriveLetter);
+  }
+}
+
+bool
+DriveToNtPath(const wchar_t aDriveLetter, nsAString& aNtPath)
+{
+  const wchar_t drvTpl[] = {aDriveLetter, L':', L'\0'};
+  aNtPath.SetLength(MAX_PATH);
+  DWORD pathLen;
+  while (true) {
+    pathLen = QueryDosDeviceW(drvTpl, reinterpret_cast<wchar_t*>(aNtPath.BeginWriting()), aNtPath.Length());
+    if (pathLen || GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
+      break;
+    }
+    aNtPath.SetLength(aNtPath.Length() * 2);
+  }
+  if (!pathLen) {
+    return false;
+  }
+  // aNtPath contains embedded NULLs, so we need to figure out the real length
+  // via wcslen.
+  aNtPath.SetLength(NS_strlen(aNtPath.BeginReading()));
+  return true;
+}
+
+bool
+TestNtPathToDosPath(const wchar_t* aNtPath,
+                    const wchar_t* aExpectedDosPath)
+{
+  nsAutoString output;
+  bool result = mozilla::NtPathToDosPath(nsDependentString(aNtPath), output);
+  return result && output == reinterpret_cast<const nsAString::char_type *>(aExpectedDosPath);
+}
+
+TEST(NtPathToDosPath, Tests)
+{
+  nsAutoString cDrive;
+  ASSERT_TRUE(DriveToNtPath(L'C', cDrive));
+
+  // empty string
+  EXPECT_TRUE(TestNtPathToDosPath(L"", L""));
+
+  // non-existent device, must fail
+  EXPECT_FALSE(TestNtPathToDosPath(L"\\Device\\ThisDeviceDoesNotExist\\Foo", nullptr));
+
+  // base case
+  nsAutoString testPath(cDrive);
+  testPath.Append(L"\\Program Files");
+  EXPECT_TRUE(TestNtPathToDosPath(testPath.get(), L"C:\\Program Files"));
+
+  // short filename
+  nsAutoString ntShortName(cDrive);
+  ntShortName.Append(L"\\progra~1");
+  EXPECT_TRUE(TestNtPathToDosPath(ntShortName.get(), L"C:\\Program Files"));
+
+  // drive letters as symbolic links (NtCreateFile uses these)
+  EXPECT_TRUE(TestNtPathToDosPath(L"\\??\\C:\\Foo", L"C:\\Foo"));
+
+  // other symbolic links (should fail)
+  EXPECT_FALSE(TestNtPathToDosPath(L"\\??\\MountPointManager", nullptr));
+
+  // socket (should fail)
+  EXPECT_FALSE(TestNtPathToDosPath(L"\\Device\\Afd\\Endpoint", nullptr));
+
+  // UNC path (using MUP)
+  EXPECT_TRUE(TestNtPathToDosPath(L"\\Device\\Mup\\127.0.0.1\\C$",
+                           L"\\\\127.0.0.1\\C$"));
+
+  // UNC path (using LanmanRedirector)
+  EXPECT_TRUE(TestNtPathToDosPath(L"\\Device\\LanmanRedirector\\127.0.0.1\\C$",
+                           L"\\\\127.0.0.1\\C$"));
+
+  DriveMapping drvMapping(NS_LITERAL_STRING("\\\\127.0.0.1\\C$"));
+  // Only run these tests if we were able to map; some machines don't have perms
+  if (drvMapping.Init()) {
+    wchar_t expected[] = L" :\\";
+    expected[0] = drvMapping.GetDriveLetter();
+    nsAutoString networkPath;
+    ASSERT_TRUE(DriveToNtPath(drvMapping.GetDriveLetter(), networkPath));
+
+    networkPath += u"\\";
+    EXPECT_TRUE(TestNtPathToDosPath(networkPath.get(), expected));
+
+    // NtPathToDosPath must correctly handle paths whose drive letter mapping has
+    // changed. We need to test this because the APIs called by NtPathToDosPath
+    // return different info if this has happened.
+    ASSERT_TRUE(drvMapping.ChangeDriveLetter());
+
+    expected[0] = drvMapping.GetDriveLetter();
+    ASSERT_TRUE(DriveToNtPath(drvMapping.GetDriveLetter(), networkPath));
+
+    networkPath += u"\\";
+    EXPECT_TRUE(TestNtPathToDosPath(networkPath.get(), expected));
+  }
+}
diff --git a/xpcom/tests/windows/TestWinFileAttribs.cpp b/xpcom/tests/windows/TestWinFileAttribs.cpp
new file mode 100644
index 000000000..56fbcbdea
--- /dev/null
+++ b/xpcom/tests/windows/TestWinFileAttribs.cpp
@@ -0,0 +1,173 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Test: 
+ */
+
+#include "../TestHarness.h"
+#include "nsEmbedString.h"
+#include "nsILocalFileWin.h"
+#include <windows.h>
+
+#define BUFFSIZE 512
+
+nsresult TestWinAttribs()
+{
+
+    nsresult rv;
+
+    // File variables
+    HANDLE hIndexed;
+    nsCOMPtr<nsIFile> localFile;
+    WCHAR filePath[MAX_PATH];
+
+    // Create and open temporary file
+    hIndexed = CreateFileW(L".\\indexbit.txt", 
+                            GENERIC_READ | GENERIC_WRITE,
+                            0, 
+                            nullptr,
+                            CREATE_ALWAYS,        
+                            FILE_ATTRIBUTE_NORMAL, //FILE_ATTRIBUTE_NOT_CONTENT_INDEXED, not supported by cf
+                            nullptr);  
+
+    if(hIndexed == INVALID_HANDLE_VALUE)
+    {
+        fail("Test Win Attribs: Creating Test File");
+        return NS_ERROR_FAILURE;
+    }
+
+    CloseHandle(hIndexed);
+
+    GetFullPathNameW((LPCWSTR)L".\\indexbit.txt", 
+                        MAX_PATH, filePath, nullptr);
+
+    //wprintf(filePath);
+    //wprintf(L"\n");
+
+    rv = NS_NewLocalFile(nsEmbedString(filePath), false,
+                         getter_AddRefs(localFile));
+    if (NS_FAILED(rv))
+    {
+        fail("Test Win Attribs: Opening Test File");
+        DeleteFileW(filePath);
+        return rv;
+    }
+
+    nsCOMPtr<nsILocalFileWin> localFileWin(do_QueryInterface(localFile));
+
+    DWORD dwAttrs = GetFileAttributesW(filePath);
+    if (dwAttrs == INVALID_FILE_ATTRIBUTES)
+    {
+        fail("Test Win Attribs: GetFileAttributesW - couldn't find our temp file.");
+        DeleteFileW(filePath);
+        return NS_ERROR_FAILURE;
+    }
+
+    dwAttrs |= FILE_ATTRIBUTE_NOT_CONTENT_INDEXED;
+    SetFileAttributesW(filePath, dwAttrs);
+
+    uint32_t attribs = 0;
+    rv = localFileWin->GetFileAttributesWin(&attribs);
+    
+    if (NS_FAILED(rv))
+    {
+        fail("Test Win Attribs: GetFileAttributesWin failed to GET attributes. (1)");
+        DeleteFileW(filePath);
+        return NS_ERROR_FAILURE;
+    }
+    
+    if (attribs & nsILocalFileWin::WFA_SEARCH_INDEXED)
+    {
+        fail("Test Win Attribs: GetFileAttributesWin attributed did not match. (2)");
+        DeleteFileW(filePath);
+        return NS_ERROR_FAILURE;
+    }
+
+    dwAttrs &= ~FILE_ATTRIBUTE_NOT_CONTENT_INDEXED;
+    SetFileAttributesW(filePath, dwAttrs);
+
+    rv = localFileWin->GetFileAttributesWin(&attribs);
+    
+    if (NS_FAILED(rv))
+    {
+        fail("Test Win Attribs: GetFileAttributesWin failed to GET attributes. (3)");
+        DeleteFileW(filePath);
+        return NS_ERROR_FAILURE;
+    }
+
+    if (!(attribs & nsILocalFileWin::WFA_SEARCH_INDEXED))
+    {
+        fail("Test Win Attribs: GetFileAttributesWin attributed did not match. (4)");
+        DeleteFileW(filePath);
+        return NS_ERROR_FAILURE;
+    }
+
+    dwAttrs &= ~FILE_ATTRIBUTE_NOT_CONTENT_INDEXED;
+    SetFileAttributesW(filePath, dwAttrs);
+
+    attribs = nsILocalFileWin::WFA_SEARCH_INDEXED;
+    rv = localFileWin->SetFileAttributesWin(attribs);
+
+    dwAttrs = GetFileAttributesW(filePath);
+
+    if (NS_FAILED(rv))
+    {
+        fail("Test Win Attribs: GetFileAttributesWin failed to SET attributes. (5)");
+        DeleteFileW(filePath);
+        return NS_ERROR_FAILURE;
+    }
+
+    if (dwAttrs & FILE_ATTRIBUTE_NOT_CONTENT_INDEXED)
+    {
+        fail("Test Win Attribs: SetFileAttributesWin attributed did not match. (6)");
+        DeleteFileW(filePath);
+        return NS_ERROR_FAILURE;
+    }
+    
+    dwAttrs |= FILE_ATTRIBUTE_NOT_CONTENT_INDEXED;
+    SetFileAttributesW(filePath, dwAttrs);
+
+    attribs = 0;
+    rv = localFileWin->SetFileAttributesWin(attribs);
+
+    dwAttrs = GetFileAttributesW(filePath);
+
+    if (NS_FAILED(rv))
+    {
+        fail("Test Win Attribs: GetFileAttributesWin failed to SET attributes. (7)");
+        DeleteFileW(filePath);
+        return NS_ERROR_FAILURE;
+    }
+
+    if (!(dwAttrs & FILE_ATTRIBUTE_NOT_CONTENT_INDEXED))
+    {
+        fail("Test Win Attribs: SetFileAttributesWin attributed did not match. (8)");
+        DeleteFileW(filePath);
+        return NS_ERROR_FAILURE;
+    }
+
+    DeleteFileW(filePath);
+
+    passed("Test Win Attribs: passed tests.");
+
+    return NS_OK;
+}
+
+int main(int argc, char** argv)
+{
+    ScopedXPCOM xpcom("WinFileAttributes");
+    if (xpcom.failed())
+        return 1;
+
+    int rv = 0;
+
+    if(NS_FAILED(TestWinAttribs()))
+        rv = 1;
+
+    return rv;
+
+}
+
diff --git a/xpcom/tests/windows/moz.build b/xpcom/tests/windows/moz.build
new file mode 100644
index 000000000..21b5eb2f7
--- /dev/null
+++ b/xpcom/tests/windows/moz.build
@@ -0,0 +1,16 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+UNIFIED_SOURCES += [
+    'TestCOM.cpp',
+    'TestNtPathToDosPath.cpp',
+]
+
+OS_LIBS += [
+    'mpr',
+]
+
+FINAL_LIBRARY = 'xul-gtest'
diff --git a/xpcom/threads/AbstractThread.cpp b/xpcom/threads/AbstractThread.cpp
new file mode 100644
index 000000000..451b317d8
--- /dev/null
+++ b/xpcom/threads/AbstractThread.cpp
@@ -0,0 +1,192 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/AbstractThread.h"
+
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/MozPromise.h" // We initialize the MozPromise logging in this file.
+#include "mozilla/StaticPtr.h"
+#include "mozilla/StateWatching.h" // We initialize the StateWatching logging in this file.
+#include "mozilla/TaskQueue.h"
+#include "mozilla/TaskDispatcher.h"
+#include "mozilla/Unused.h"
+
+#include "nsThreadUtils.h"
+#include "nsContentUtils.h"
+#include "nsServiceManagerUtils.h"
+
+
+namespace mozilla {
+
+LazyLogModule gMozPromiseLog("MozPromise");
+LazyLogModule gStateWatchingLog("StateWatching");
+
+StaticRefPtr<AbstractThread> sMainThread;
+MOZ_THREAD_LOCAL(AbstractThread*) AbstractThread::sCurrentThreadTLS;
+
+class XPCOMThreadWrapper : public AbstractThread
+{
+public:
+  explicit XPCOMThreadWrapper(nsIThread* aTarget, bool aRequireTailDispatch)
+    : AbstractThread(aRequireTailDispatch)
+    , mTarget(aTarget)
+  {
+    // Our current mechanism of implementing tail dispatch is appshell-specific.
+    // This is because a very similar mechanism already exists on the main
+    // thread, and we want to avoid making event dispatch on the main thread
+    // more complicated than it already is.
+    //
+    // If you need to use tail dispatch on other XPCOM threads, you'll need to
+    // implement an nsIThreadObserver to fire the tail dispatcher at the
+    // appropriate times.
+    MOZ_ASSERT_IF(aRequireTailDispatch,
+                  NS_IsMainThread() && NS_GetCurrentThread() == aTarget);
+  }
+
+  virtual void Dispatch(already_AddRefed<nsIRunnable> aRunnable,
+                        DispatchFailureHandling aFailureHandling = AssertDispatchSuccess,
+                        DispatchReason aReason = NormalDispatch) override
+  {
+    nsCOMPtr<nsIRunnable> r = aRunnable;
+    AbstractThread* currentThread;
+    if (aReason != TailDispatch && (currentThread = GetCurrent()) && RequiresTailDispatch(currentThread)) {
+      currentThread->TailDispatcher().AddTask(this, r.forget(), aFailureHandling);
+      return;
+    }
+
+    nsresult rv = mTarget->Dispatch(r, NS_DISPATCH_NORMAL);
+    MOZ_DIAGNOSTIC_ASSERT(aFailureHandling == DontAssertDispatchSuccess || NS_SUCCEEDED(rv));
+    Unused << rv;
+  }
+
+  virtual bool IsCurrentThreadIn() override
+  {
+    // Compare NSPR threads so that this works after shutdown when
+    // NS_GetCurrentThread starts returning null.
+    PRThread* thread = nullptr;
+    mTarget->GetPRThread(&thread);
+    bool in = PR_GetCurrentThread() == thread;
+    return in;
+  }
+
+  void FireTailDispatcher()
+  {
+    MOZ_DIAGNOSTIC_ASSERT(mTailDispatcher.isSome());
+    mTailDispatcher.ref().DrainDirectTasks();
+    mTailDispatcher.reset();
+  }
+
+  virtual TaskDispatcher& TailDispatcher() override
+  {
+    MOZ_ASSERT(this == sMainThread); // See the comment in the constructor.
+    MOZ_ASSERT(IsCurrentThreadIn());
+    if (!mTailDispatcher.isSome()) {
+      mTailDispatcher.emplace(/* aIsTailDispatcher = */ true);
+
+      nsCOMPtr<nsIRunnable> event = NewRunnableMethod(this, &XPCOMThreadWrapper::FireTailDispatcher);
+      nsContentUtils::RunInStableState(event.forget());
+    }
+
+    return mTailDispatcher.ref();
+  }
+
+  virtual bool MightHaveTailTasks() override
+  {
+    return mTailDispatcher.isSome();
+  }
+
+  virtual nsIThread* AsXPCOMThread() override { return mTarget; }
+
+private:
+  RefPtr<nsIThread> mTarget;
+  Maybe<AutoTaskDispatcher> mTailDispatcher;
+};
+
+void
+AbstractThread::TailDispatchTasksFor(AbstractThread* aThread)
+{
+  if (MightHaveTailTasks()) {
+    TailDispatcher().DispatchTasksFor(aThread);
+  }
+}
+
+bool
+AbstractThread::HasTailTasksFor(AbstractThread* aThread)
+{
+  if (!MightHaveTailTasks()) {
+    return false;
+  }
+  return TailDispatcher().HasTasksFor(aThread);
+}
+
+bool
+AbstractThread::RequiresTailDispatch(AbstractThread* aThread) const
+{
+  MOZ_ASSERT(aThread);
+  // We require tail dispatch if both the source and destination
+  // threads support it.
+  return SupportsTailDispatch() && aThread->SupportsTailDispatch();
+}
+
+bool
+AbstractThread::RequiresTailDispatchFromCurrentThread() const
+{
+  AbstractThread* current = GetCurrent();
+  return current && RequiresTailDispatch(current);
+}
+
+AbstractThread*
+AbstractThread::MainThread()
+{
+  MOZ_ASSERT(sMainThread);
+  return sMainThread;
+}
+
+void
+AbstractThread::InitStatics()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!sMainThread);
+  nsCOMPtr<nsIThread> mainThread;
+  NS_GetMainThread(getter_AddRefs(mainThread));
+  MOZ_DIAGNOSTIC_ASSERT(mainThread);
+  sMainThread = new XPCOMThreadWrapper(mainThread.get(), /* aRequireTailDispatch = */ true);
+  ClearOnShutdown(&sMainThread);
+
+  if (!sCurrentThreadTLS.init()) {
+    MOZ_CRASH();
+  }
+  sCurrentThreadTLS.set(sMainThread);
+}
+
+void
+AbstractThread::DispatchStateChange(already_AddRefed<nsIRunnable> aRunnable)
+{
+  GetCurrent()->TailDispatcher().AddStateChangeTask(this, Move(aRunnable));
+}
+
+/* static */ void
+AbstractThread::DispatchDirectTask(already_AddRefed<nsIRunnable> aRunnable)
+{
+  GetCurrent()->TailDispatcher().AddDirectTask(Move(aRunnable));
+}
+
+/* static */
+already_AddRefed<AbstractThread>
+AbstractThread::CreateXPCOMThreadWrapper(nsIThread* aThread, bool aRequireTailDispatch)
+{
+  RefPtr<XPCOMThreadWrapper> wrapper = new XPCOMThreadWrapper(aThread, aRequireTailDispatch);
+  // Set the thread-local sCurrentThreadTLS to point to the wrapper on the
+  // target thread. This ensures that sCurrentThreadTLS is as expected by
+  // AbstractThread::GetCurrent() on the target thread.
+  nsCOMPtr<nsIRunnable> r =
+    NS_NewRunnableFunction([wrapper]() { sCurrentThreadTLS.set(wrapper); });
+  aThread->Dispatch(r.forget(), NS_DISPATCH_NORMAL);
+  return wrapper.forget();
+}
+
+} // namespace mozilla
diff --git a/xpcom/threads/AbstractThread.h b/xpcom/threads/AbstractThread.h
new file mode 100644
index 000000000..ca6ec1b84
--- /dev/null
+++ b/xpcom/threads/AbstractThread.h
@@ -0,0 +1,111 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#if !defined(AbstractThread_h_)
+#define AbstractThread_h_
+
+#include "nscore.h"
+#include "nsIRunnable.h"
+#include "nsISupportsImpl.h"
+#include "nsIThread.h"
+#include "mozilla/RefPtr.h"
+
+#include "mozilla/ThreadLocal.h"
+
+namespace mozilla {
+
+class TaskQueue;
+class TaskDispatcher;
+
+/*
+ * We often want to run tasks on a target that guarantees that events will never
+ * run in parallel. There are various target types that achieve this - namely
+ * nsIThread and TaskQueue. Note that nsIThreadPool (which implements
+ * nsIEventTarget) does not have this property, so we do not want to use
+ * nsIEventTarget for this purpose. This class encapsulates the specifics of
+ * the structures we might use here and provides a consistent interface.
+ *
+ * At present, the supported AbstractThread implementations are TaskQueue
+ * and AbstractThread::MainThread. If you add support for another thread that is
+ * not the MainThread, you'll need to figure out how to make it unique such that
+ * comparing AbstractThread pointers is equivalent to comparing nsIThread pointers.
+ */
+class AbstractThread
+{
+public:
+  // Returns the AbstractThread that the caller is currently running in, or null
+  // if the caller is not running in an AbstractThread.
+  static AbstractThread* GetCurrent() { return sCurrentThreadTLS.get(); }
+
+  AbstractThread(bool aSupportsTailDispatch) : mSupportsTailDispatch(aSupportsTailDispatch) {}
+
+  static already_AddRefed<AbstractThread>
+  CreateXPCOMThreadWrapper(nsIThread* aThread, bool aRequireTailDispatch);
+
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(AbstractThread);
+
+  enum DispatchFailureHandling { AssertDispatchSuccess, DontAssertDispatchSuccess };
+  enum DispatchReason { NormalDispatch, TailDispatch };
+  virtual void Dispatch(already_AddRefed<nsIRunnable> aRunnable,
+                        DispatchFailureHandling aHandling = AssertDispatchSuccess,
+                        DispatchReason aReason = NormalDispatch) = 0;
+
+  virtual bool IsCurrentThreadIn() = 0;
+
+  // Returns true if dispatch is generally reliable. This is used to guard
+  // against FlushableTaskQueues, which should go away.
+  virtual bool IsDispatchReliable() { return true; }
+
+  // Returns a TaskDispatcher that will dispatch its tasks when the currently-
+  // running tasks pops off the stack.
+  //
+  // May only be called when running within the it is invoked up, and only on
+  // threads which support it.
+  virtual TaskDispatcher& TailDispatcher() = 0;
+
+  // Returns true if we have tail tasks scheduled, or if this isn't known.
+  // Returns false if we definitely don't have any tail tasks.
+  virtual bool MightHaveTailTasks() { return true; }
+
+  // Helper functions for methods on the tail TasklDispatcher. These check
+  // HasTailTasks to avoid allocating a TailDispatcher if it isn't
+  // needed.
+  void TailDispatchTasksFor(AbstractThread* aThread);
+  bool HasTailTasksFor(AbstractThread* aThread);
+
+  // Returns true if this supports the tail dispatcher.
+  bool SupportsTailDispatch() const { return mSupportsTailDispatch; }
+
+  // Returns true if this thread requires all dispatches originating from
+  // aThread go through the tail dispatcher.
+  bool RequiresTailDispatch(AbstractThread* aThread) const;
+  bool RequiresTailDispatchFromCurrentThread() const;
+
+  virtual TaskQueue* AsTaskQueue() { MOZ_CRASH("Not a task queue!"); }
+  virtual nsIThread* AsXPCOMThread() { MOZ_CRASH("Not an XPCOM thread!"); }
+
+  // Convenience method for getting an AbstractThread for the main thread.
+  static AbstractThread* MainThread();
+
+  // Must be called exactly once during startup.
+  static void InitStatics();
+
+  void DispatchStateChange(already_AddRefed<nsIRunnable> aRunnable);
+
+  static void DispatchDirectTask(already_AddRefed<nsIRunnable> aRunnable);
+
+protected:
+  virtual ~AbstractThread() {}
+  static MOZ_THREAD_LOCAL(AbstractThread*) sCurrentThreadTLS;
+
+  // True if we want to require that every task dispatched from tasks running in
+  // this queue go through our queue's tail dispatcher.
+  const bool mSupportsTailDispatch;
+};
+
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/threads/BackgroundHangMonitor.cpp b/xpcom/threads/BackgroundHangMonitor.cpp
new file mode 100644
index 000000000..ac65d9f37
--- /dev/null
+++ b/xpcom/threads/BackgroundHangMonitor.cpp
@@ -0,0 +1,734 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/BackgroundHangMonitor.h"
+#include "mozilla/LinkedList.h"
+#include "mozilla/Monitor.h"
+#include "mozilla/Move.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/ThreadHangStats.h"
+#include "mozilla/ThreadLocal.h"
+
+#include "prinrval.h"
+#include "prthread.h"
+#include "ThreadStackHelper.h"
+#include "nsIObserverService.h"
+#include "nsIObserver.h"
+#include "mozilla/Services.h"
+#include "nsXULAppAPI.h"
+
+#include <algorithm>
+
+// Activate BHR only for one every BHR_BETA_MOD users.
+// This is now 100% of Beta population for the Beta 45/46 e10s A/B trials
+// It can be scaled back again in the future
+#define BHR_BETA_MOD 1;
+
+// Maximum depth of the call stack in the reported thread hangs. This value represents
+// the 99.9th percentile of the thread hangs stack depths reported by Telemetry.
+static const size_t kMaxThreadHangStackDepth = 30;
+
+// An utility comparator function used by std::unique to collapse "(* script)" entries in
+// a vector representing a call stack.
+bool StackScriptEntriesCollapser(const char* aStackEntry, const char *aAnotherStackEntry)
+{
+  return !strcmp(aStackEntry, aAnotherStackEntry) &&
+         (!strcmp(aStackEntry, "(chrome script)") || !strcmp(aStackEntry, "(content script)"));
+}
+
+namespace mozilla {
+
+/**
+ * BackgroundHangManager is the global object that
+ * manages all instances of BackgroundHangThread.
+ */
+class BackgroundHangManager : public nsIObserver
+{
+private:
+  // Background hang monitor thread function
+  static void MonitorThread(void* aData)
+  {
+    PR_SetCurrentThreadName("BgHangManager");
+
+    /* We do not hold a reference to BackgroundHangManager here
+       because the monitor thread only exists as long as the
+       BackgroundHangManager instance exists. We stop the monitor
+       thread in the BackgroundHangManager destructor, and we can
+       only get to the destructor if we don't hold a reference here. */
+    static_cast<BackgroundHangManager*>(aData)->RunMonitorThread();
+  }
+
+  // Hang monitor thread
+  PRThread* mHangMonitorThread;
+  // Stop hang monitoring
+  bool mShutdown;
+
+  BackgroundHangManager(const BackgroundHangManager&);
+  BackgroundHangManager& operator=(const BackgroundHangManager&);
+  void RunMonitorThread();
+
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+  static StaticRefPtr<BackgroundHangManager> sInstance;
+  static bool sDisabled;
+
+  // Lock for access to members of this class
+  Monitor mLock;
+  // Current time as seen by hang monitors
+  PRIntervalTime mIntervalNow;
+  // List of BackgroundHangThread instances associated with each thread
+  LinkedList<BackgroundHangThread> mHangThreads;
+
+  void Shutdown()
+  {
+    MonitorAutoLock autoLock(mLock);
+    mShutdown = true;
+    autoLock.Notify();
+  }
+
+  void Wakeup()
+  {
+    // PR_CreateThread could have failed earlier
+    if (mHangMonitorThread) {
+      // Use PR_Interrupt to avoid potentially taking a lock
+      PR_Interrupt(mHangMonitorThread);
+    }
+  }
+
+  BackgroundHangManager();
+private:
+  virtual ~BackgroundHangManager();
+};
+
+NS_IMPL_ISUPPORTS(BackgroundHangManager, nsIObserver)
+
+NS_IMETHODIMP
+BackgroundHangManager::Observe(nsISupports* aSubject, const char* aTopic, const char16_t* aData) {
+  NS_ENSURE_TRUE(!strcmp(aTopic, "profile-after-change"), NS_ERROR_UNEXPECTED);
+  BackgroundHangMonitor::DisableOnBeta();
+
+  nsCOMPtr<nsIObserverService> observerService = mozilla::services::GetObserverService();
+  MOZ_ASSERT(observerService);
+  observerService->RemoveObserver(this, "profile-after-change");
+
+  return NS_OK;
+}
+
+/**
+ * BackgroundHangThread is a per-thread object that is used
+ * by all instances of BackgroundHangMonitor to monitor hangs.
+ */
+class BackgroundHangThread : public LinkedListElement<BackgroundHangThread>
+{
+private:
+  static MOZ_THREAD_LOCAL(BackgroundHangThread*) sTlsKey;
+  static bool sTlsKeyInitialized;
+
+  BackgroundHangThread(const BackgroundHangThread&);
+  BackgroundHangThread& operator=(const BackgroundHangThread&);
+  ~BackgroundHangThread();
+
+  /* Keep a reference to the manager, so we can keep going even
+     after BackgroundHangManager::Shutdown is called. */
+  const RefPtr<BackgroundHangManager> mManager;
+  // Unique thread ID for identification
+  const PRThread* mThreadID;
+
+  void Update();
+
+public:
+  NS_INLINE_DECL_REFCOUNTING(BackgroundHangThread)
+  /**
+   * Returns the BackgroundHangThread associated with the
+   * running thread. Note that this will not find private
+   * BackgroundHangThread threads.
+   *
+   * @return BackgroundHangThread*, or nullptr if no thread
+   *         is found.
+   */
+  static BackgroundHangThread* FindThread();
+
+  static void Startup()
+  {
+    /* We can tolerate init() failing. */
+    sTlsKeyInitialized = sTlsKey.init();
+  }
+
+  // Hang timeout in ticks
+  const PRIntervalTime mTimeout;
+  // PermaHang timeout in ticks
+  const PRIntervalTime mMaxTimeout;
+  // Time at last activity
+  PRIntervalTime mInterval;
+  // Time when a hang started
+  PRIntervalTime mHangStart;
+  // Is the thread in a hang
+  bool mHanging;
+  // Is the thread in a waiting state
+  bool mWaiting;
+  // Is the thread dedicated to a single BackgroundHangMonitor
+  BackgroundHangMonitor::ThreadType mThreadType;
+  // Platform-specific helper to get hang stacks
+  ThreadStackHelper mStackHelper;
+  // Stack of current hang
+  Telemetry::HangStack mHangStack;
+  // Statistics for telemetry
+  Telemetry::ThreadHangStats mStats;
+  // Annotations for the current hang
+  UniquePtr<HangMonitor::HangAnnotations> mAnnotations;
+  // Annotators registered for this thread
+  HangMonitor::Observer::Annotators mAnnotators;
+
+  BackgroundHangThread(const char* aName,
+                       uint32_t aTimeoutMs,
+                       uint32_t aMaxTimeoutMs,
+                       BackgroundHangMonitor::ThreadType aThreadType = BackgroundHangMonitor::THREAD_SHARED);
+
+  // Report a hang; aManager->mLock IS locked
+  Telemetry::HangHistogram& ReportHang(PRIntervalTime aHangTime);
+  // Report a permanent hang; aManager->mLock IS locked
+  void ReportPermaHang();
+  // Called by BackgroundHangMonitor::NotifyActivity
+  void NotifyActivity()
+  {
+    MonitorAutoLock autoLock(mManager->mLock);
+    Update();
+  }
+  // Called by BackgroundHangMonitor::NotifyWait
+  void NotifyWait()
+  {
+    MonitorAutoLock autoLock(mManager->mLock);
+
+    if (mWaiting) {
+      return;
+    }
+
+    Update();
+    mWaiting = true;
+  }
+
+  // Returns true if this thread is (or might be) shared between other
+  // BackgroundHangMonitors for the monitored thread.
+  bool IsShared() {
+    return mThreadType == BackgroundHangMonitor::THREAD_SHARED;
+  }
+};
+
+
+StaticRefPtr<BackgroundHangManager> BackgroundHangManager::sInstance;
+bool BackgroundHangManager::sDisabled = false;
+
+MOZ_THREAD_LOCAL(BackgroundHangThread*) BackgroundHangThread::sTlsKey;
+bool BackgroundHangThread::sTlsKeyInitialized;
+
+BackgroundHangManager::BackgroundHangManager()
+  : mShutdown(false)
+  , mLock("BackgroundHangManager")
+  , mIntervalNow(0)
+{
+  // Lock so we don't race against the new monitor thread
+  MonitorAutoLock autoLock(mLock);
+  mHangMonitorThread = PR_CreateThread(
+    PR_USER_THREAD, MonitorThread, this,
+    PR_PRIORITY_LOW, PR_GLOBAL_THREAD, PR_JOINABLE_THREAD, 0);
+
+  MOZ_ASSERT(mHangMonitorThread, "Failed to create monitor thread");
+}
+
+BackgroundHangManager::~BackgroundHangManager()
+{
+  MOZ_ASSERT(mShutdown, "Destruction without Shutdown call");
+  MOZ_ASSERT(mHangThreads.isEmpty(), "Destruction with outstanding monitors");
+  MOZ_ASSERT(mHangMonitorThread, "No monitor thread");
+
+  // PR_CreateThread could have failed above due to resource limitation
+  if (mHangMonitorThread) {
+    // The monitor thread can only live as long as the instance lives
+    PR_JoinThread(mHangMonitorThread);
+  }
+}
+
+void
+BackgroundHangManager::RunMonitorThread()
+{
+  // Keep us locked except when waiting
+  MonitorAutoLock autoLock(mLock);
+
+  /* mIntervalNow is updated at various intervals determined by waitTime.
+     However, if an update latency is too long (due to CPU scheduling, system
+     sleep, etc.), we don't update mIntervalNow at all. This is done so that
+     long latencies in our timing are not detected as hangs. systemTime is
+     used to track PR_IntervalNow() and determine our latency. */
+
+  PRIntervalTime systemTime = PR_IntervalNow();
+  // Default values for the first iteration of thread loop
+  PRIntervalTime waitTime = PR_INTERVAL_NO_WAIT;
+  PRIntervalTime recheckTimeout = PR_INTERVAL_NO_WAIT;
+
+  while (!mShutdown) {
+
+    PR_ClearInterrupt();
+    nsresult rv = autoLock.Wait(waitTime);
+
+    PRIntervalTime newTime = PR_IntervalNow();
+    PRIntervalTime systemInterval = newTime - systemTime;
+    systemTime = newTime;
+
+    /* waitTime is a quarter of the shortest timeout value; If our timing
+       latency is low enough (less than half the shortest timeout value),
+       we can update mIntervalNow. */
+    if (MOZ_LIKELY(waitTime != PR_INTERVAL_NO_TIMEOUT &&
+                   systemInterval < 2 * waitTime)) {
+      mIntervalNow += systemInterval;
+    }
+
+    /* If it's before the next recheck timeout, and our wait did not
+       get interrupted (either through Notify or PR_Interrupt), we can
+       keep the current waitTime and skip iterating through hang monitors. */
+    if (MOZ_LIKELY(systemInterval < recheckTimeout &&
+                   systemInterval >= waitTime &&
+                   rv == NS_OK)) {
+      recheckTimeout -= systemInterval;
+      continue;
+    }
+
+    /* We are in one of the following scenarios,
+     - Hang or permahang recheck timeout
+     - Thread added/removed
+     - Thread wait or hang ended
+       In all cases, we want to go through our list of hang
+       monitors and update waitTime and recheckTimeout. */
+    waitTime = PR_INTERVAL_NO_TIMEOUT;
+    recheckTimeout = PR_INTERVAL_NO_TIMEOUT;
+
+    // Locally hold mIntervalNow
+    PRIntervalTime intervalNow = mIntervalNow;
+
+    // iterate through hang monitors
+    for (BackgroundHangThread* currentThread = mHangThreads.getFirst();
+         currentThread; currentThread = currentThread->getNext()) {
+
+      if (currentThread->mWaiting) {
+        // Thread is waiting, not hanging
+        continue;
+      }
+      PRIntervalTime interval = currentThread->mInterval;
+      PRIntervalTime hangTime = intervalNow - interval;
+      if (MOZ_UNLIKELY(hangTime >= currentThread->mMaxTimeout)) {
+        // A permahang started
+        // Skip subsequent iterations and tolerate a race on mWaiting here
+        currentThread->mWaiting = true;
+        currentThread->mHanging = false;
+        currentThread->ReportPermaHang();
+        continue;
+      }
+
+      if (MOZ_LIKELY(!currentThread->mHanging)) {
+        if (MOZ_UNLIKELY(hangTime >= currentThread->mTimeout)) {
+          // A hang started
+          currentThread->mStackHelper.GetStack(currentThread->mHangStack);
+          currentThread->mHangStart = interval;
+          currentThread->mHanging = true;
+          currentThread->mAnnotations =
+            currentThread->mAnnotators.GatherAnnotations();
+        }
+      } else {
+        if (MOZ_LIKELY(interval != currentThread->mHangStart)) {
+          // A hang ended
+          currentThread->ReportHang(intervalNow - currentThread->mHangStart);
+          currentThread->mHanging = false;
+        }
+      }
+
+      /* If we are hanging, the next time we check for hang status is when
+         the hang turns into a permahang. If we're not hanging, the next
+         recheck timeout is when we may be entering a hang. */
+      PRIntervalTime nextRecheck;
+      if (currentThread->mHanging) {
+        nextRecheck = currentThread->mMaxTimeout;
+      } else {
+        nextRecheck = currentThread->mTimeout;
+      }
+      recheckTimeout = std::min(recheckTimeout, nextRecheck - hangTime);
+
+      if (currentThread->mTimeout != PR_INTERVAL_NO_TIMEOUT) {
+        /* We wait for a quarter of the shortest timeout
+           value to give mIntervalNow enough granularity. */
+        waitTime = std::min(waitTime, currentThread->mTimeout / 4);
+      }
+    }
+  }
+
+  /* We are shutting down now.
+     Wait for all outstanding monitors to unregister. */
+  while (!mHangThreads.isEmpty()) {
+    autoLock.Wait(PR_INTERVAL_NO_TIMEOUT);
+  }
+}
+
+
+BackgroundHangThread::BackgroundHangThread(const char* aName,
+                                           uint32_t aTimeoutMs,
+                                           uint32_t aMaxTimeoutMs,
+                                           BackgroundHangMonitor::ThreadType aThreadType)
+  : mManager(BackgroundHangManager::sInstance)
+  , mThreadID(PR_GetCurrentThread())
+  , mTimeout(aTimeoutMs == BackgroundHangMonitor::kNoTimeout
+             ? PR_INTERVAL_NO_TIMEOUT
+             : PR_MillisecondsToInterval(aTimeoutMs))
+  , mMaxTimeout(aMaxTimeoutMs == BackgroundHangMonitor::kNoTimeout
+                ? PR_INTERVAL_NO_TIMEOUT
+                : PR_MillisecondsToInterval(aMaxTimeoutMs))
+  , mInterval(mManager->mIntervalNow)
+  , mHangStart(mInterval)
+  , mHanging(false)
+  , mWaiting(true)
+  , mThreadType(aThreadType)
+  , mStats(aName)
+{
+  if (sTlsKeyInitialized && IsShared()) {
+    sTlsKey.set(this);
+  }
+  // Lock here because LinkedList is not thread-safe
+  MonitorAutoLock autoLock(mManager->mLock);
+  // Add to thread list
+  mManager->mHangThreads.insertBack(this);
+  // Wake up monitor thread to process new thread
+  autoLock.Notify();
+}
+
+BackgroundHangThread::~BackgroundHangThread()
+{
+  // Lock here because LinkedList is not thread-safe
+  MonitorAutoLock autoLock(mManager->mLock);
+  // Remove from thread list
+  remove();
+  // Wake up monitor thread to process removed thread
+  autoLock.Notify();
+
+  // We no longer have a thread
+  if (sTlsKeyInitialized && IsShared()) {
+    sTlsKey.set(nullptr);
+  }
+
+  // Move our copy of ThreadHangStats to Telemetry storage
+  Telemetry::RecordThreadHangStats(mStats);
+}
+
+Telemetry::HangHistogram&
+BackgroundHangThread::ReportHang(PRIntervalTime aHangTime)
+{
+  // Recovered from a hang; called on the monitor thread
+  // mManager->mLock IS locked
+
+  // Remove unwanted "js::RunScript" frame from the stack
+  for (size_t i = 0; i < mHangStack.length(); ) {
+    const char** f = mHangStack.begin() + i;
+    if (!mHangStack.IsInBuffer(*f) && !strcmp(*f, "js::RunScript")) {
+      mHangStack.erase(f);
+    } else {
+      i++;
+    }
+  }
+
+  // Collapse duplicated "(chrome script)" and "(content script)" entries in the stack.
+  auto it = std::unique(mHangStack.begin(), mHangStack.end(), StackScriptEntriesCollapser);
+  mHangStack.erase(it, mHangStack.end());
+
+  // Limit the depth of the reported stack if greater than our limit. Only keep its
+  // last entries, since the most recent frames are at the end of the vector.
+  if (mHangStack.length() > kMaxThreadHangStackDepth) {
+    const int elementsToRemove = mHangStack.length() - kMaxThreadHangStackDepth;
+    // Replace the oldest frame with a known label so that we can tell this stack
+    // was limited.
+    mHangStack[0] = "(reduced stack)";
+    mHangStack.erase(mHangStack.begin() + 1, mHangStack.begin() + elementsToRemove);
+  }
+
+  Telemetry::HangHistogram newHistogram(Move(mHangStack));
+  for (Telemetry::HangHistogram* oldHistogram = mStats.mHangs.begin();
+       oldHistogram != mStats.mHangs.end(); oldHistogram++) {
+    if (newHistogram == *oldHistogram) {
+      // New histogram matches old one
+      oldHistogram->Add(aHangTime, Move(mAnnotations));
+      return *oldHistogram;
+    }
+  }
+  // Add new histogram
+  newHistogram.Add(aHangTime, Move(mAnnotations));
+  if (!mStats.mHangs.append(Move(newHistogram))) {
+    MOZ_CRASH();
+  }
+  return mStats.mHangs.back();
+}
+
+void
+BackgroundHangThread::ReportPermaHang()
+{
+  // Permanently hanged; called on the monitor thread
+  // mManager->mLock IS locked
+
+  Telemetry::HangHistogram& hang = ReportHang(mMaxTimeout);
+  Telemetry::HangStack& stack = hang.GetNativeStack();
+  if (stack.empty()) {
+    mStackHelper.GetNativeStack(stack);
+  }
+}
+
+MOZ_ALWAYS_INLINE void
+BackgroundHangThread::Update()
+{
+  PRIntervalTime intervalNow = mManager->mIntervalNow;
+  if (mWaiting) {
+    mInterval = intervalNow;
+    mWaiting = false;
+    /* We have to wake up the manager thread because when all threads
+       are waiting, the manager thread waits indefinitely as well. */
+    mManager->Wakeup();
+  } else {
+    PRIntervalTime duration = intervalNow - mInterval;
+    mStats.mActivity.Add(duration);
+    if (MOZ_UNLIKELY(duration >= mTimeout)) {
+      /* Wake up the manager thread to tell it that a hang ended */
+      mManager->Wakeup();
+    }
+    mInterval = intervalNow;
+  }
+}
+
+BackgroundHangThread*
+BackgroundHangThread::FindThread()
+{
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
+  if (BackgroundHangManager::sInstance == nullptr) {
+    MOZ_ASSERT(BackgroundHangManager::sDisabled,
+               "BackgroundHandleManager is not initialized");
+    return nullptr;
+  }
+
+  if (sTlsKeyInitialized) {
+    // Use TLS if available
+    return sTlsKey.get();
+  }
+  // If TLS is unavailable, we can search through the thread list
+  RefPtr<BackgroundHangManager> manager(BackgroundHangManager::sInstance);
+  MOZ_ASSERT(manager, "Creating BackgroundHangMonitor after shutdown");
+
+  PRThread* threadID = PR_GetCurrentThread();
+  // Lock thread list for traversal
+  MonitorAutoLock autoLock(manager->mLock);
+  for (BackgroundHangThread* thread = manager->mHangThreads.getFirst();
+       thread; thread = thread->getNext()) {
+    if (thread->mThreadID == threadID && thread->IsShared()) {
+      return thread;
+    }
+  }
+#endif
+  // Current thread is not initialized
+  return nullptr;
+}
+
+bool
+BackgroundHangMonitor::ShouldDisableOnBeta(const nsCString &clientID) {
+  MOZ_ASSERT(clientID.Length() == 36, "clientID is invalid");
+  const char *suffix = clientID.get() + clientID.Length() - 4;
+  return strtol(suffix, NULL, 16) % BHR_BETA_MOD;
+}
+
+bool
+BackgroundHangMonitor::IsDisabled() {
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
+  return BackgroundHangManager::sDisabled;
+#else
+  return true;
+#endif
+}
+
+bool
+BackgroundHangMonitor::DisableOnBeta() {
+  nsAdoptingCString clientID = Preferences::GetCString("toolkit.telemetry.cachedClientID");
+  bool telemetryEnabled = Preferences::GetBool("toolkit.telemetry.enabled");
+
+  if (!telemetryEnabled || !clientID || BackgroundHangMonitor::ShouldDisableOnBeta(clientID)) {
+    if (XRE_IsParentProcess()) {
+      BackgroundHangMonitor::Shutdown();
+    } else {
+      BackgroundHangManager::sDisabled = true;
+    }
+    return true;
+  }
+
+  return false;
+}
+
+void
+BackgroundHangMonitor::Startup()
+{
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
+  MOZ_ASSERT(!BackgroundHangManager::sInstance, "Already initialized");
+
+  if (!strcmp(NS_STRINGIFY(MOZ_UPDATE_CHANNEL), "beta")) {
+    if (XRE_IsParentProcess()) { // cached ClientID hasn't been read yet
+      ThreadStackHelper::Startup();
+      BackgroundHangThread::Startup();
+      BackgroundHangManager::sInstance = new BackgroundHangManager();
+
+      nsCOMPtr<nsIObserverService> observerService = mozilla::services::GetObserverService();
+      MOZ_ASSERT(observerService);
+
+      observerService->AddObserver(BackgroundHangManager::sInstance, "profile-after-change", false);
+      return;
+    } else if(DisableOnBeta()){
+      return;
+    }
+  }
+
+  ThreadStackHelper::Startup();
+  BackgroundHangThread::Startup();
+  BackgroundHangManager::sInstance = new BackgroundHangManager();
+#endif
+}
+
+void
+BackgroundHangMonitor::Shutdown()
+{
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
+  if (BackgroundHangManager::sDisabled) {
+    MOZ_ASSERT(!BackgroundHangManager::sInstance, "Initialized");
+    return;
+  }
+
+  MOZ_ASSERT(BackgroundHangManager::sInstance, "Not initialized");
+  /* Scope our lock inside Shutdown() because the sInstance object can
+     be destroyed as soon as we set sInstance to nullptr below, and
+     we don't want to hold the lock when it's being destroyed. */
+  BackgroundHangManager::sInstance->Shutdown();
+  BackgroundHangManager::sInstance = nullptr;
+  ThreadStackHelper::Shutdown();
+  BackgroundHangManager::sDisabled = true;
+#endif
+}
+
+BackgroundHangMonitor::BackgroundHangMonitor(const char* aName,
+                                             uint32_t aTimeoutMs,
+                                             uint32_t aMaxTimeoutMs,
+                                             ThreadType aThreadType)
+  : mThread(aThreadType == THREAD_SHARED ? BackgroundHangThread::FindThread() : nullptr)
+{
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
+  if (!BackgroundHangManager::sDisabled && !mThread) {
+    mThread = new BackgroundHangThread(aName, aTimeoutMs, aMaxTimeoutMs,
+                                       aThreadType);
+  }
+#endif
+}
+
+BackgroundHangMonitor::BackgroundHangMonitor()
+  : mThread(BackgroundHangThread::FindThread())
+{
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
+  if (BackgroundHangManager::sDisabled) {
+    return;
+  }
+#endif
+}
+
+BackgroundHangMonitor::~BackgroundHangMonitor()
+{
+}
+
+void
+BackgroundHangMonitor::NotifyActivity()
+{
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
+  if (mThread == nullptr) {
+    MOZ_ASSERT(BackgroundHangManager::sDisabled,
+               "This thread is not initialized for hang monitoring");
+    return;
+  }
+
+  if (Telemetry::CanRecordExtended()) {
+    mThread->NotifyActivity();
+  }
+#endif
+}
+
+void
+BackgroundHangMonitor::NotifyWait()
+{
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
+  if (mThread == nullptr) {
+    MOZ_ASSERT(BackgroundHangManager::sDisabled,
+               "This thread is not initialized for hang monitoring");
+    return;
+  }
+
+  if (Telemetry::CanRecordExtended()) {
+    mThread->NotifyWait();
+  }
+#endif
+}
+
+bool
+BackgroundHangMonitor::RegisterAnnotator(HangMonitor::Annotator& aAnnotator)
+{
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
+  BackgroundHangThread* thisThread = BackgroundHangThread::FindThread();
+  if (!thisThread) {
+    return false;
+  }
+  return thisThread->mAnnotators.Register(aAnnotator);
+#else
+  return false;
+#endif
+}
+
+bool
+BackgroundHangMonitor::UnregisterAnnotator(HangMonitor::Annotator& aAnnotator)
+{
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
+  BackgroundHangThread* thisThread = BackgroundHangThread::FindThread();
+  if (!thisThread) {
+    return false;
+  }
+  return thisThread->mAnnotators.Unregister(aAnnotator);
+#else
+  return false;
+#endif
+}
+
+/* Because we are iterating through the BackgroundHangThread linked list,
+   we need to take a lock. Using MonitorAutoLock as a base class makes
+   sure all of that is taken care of for us. */
+BackgroundHangMonitor::ThreadHangStatsIterator::ThreadHangStatsIterator()
+  : MonitorAutoLock(BackgroundHangManager::sInstance->mLock)
+  , mThread(BackgroundHangManager::sInstance ?
+            BackgroundHangManager::sInstance->mHangThreads.getFirst() :
+            nullptr)
+{
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
+  MOZ_ASSERT(BackgroundHangManager::sInstance ||
+             BackgroundHangManager::sDisabled,
+             "Inconsistent state");
+#endif
+}
+
+Telemetry::ThreadHangStats*
+BackgroundHangMonitor::ThreadHangStatsIterator::GetNext()
+{
+  if (!mThread) {
+    return nullptr;
+  }
+  Telemetry::ThreadHangStats* stats = &mThread->mStats;
+  mThread = mThread->getNext();
+  return stats;
+}
+
+} // namespace mozilla
diff --git a/xpcom/threads/BackgroundHangMonitor.h b/xpcom/threads/BackgroundHangMonitor.h
new file mode 100644
index 000000000..698cf2305
--- /dev/null
+++ b/xpcom/threads/BackgroundHangMonitor.h
@@ -0,0 +1,246 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_BackgroundHangMonitor_h
+#define mozilla_BackgroundHangMonitor_h
+
+#include "mozilla/HangAnnotations.h"
+#include "mozilla/Monitor.h"
+#include "mozilla/RefPtr.h"
+
+#include "nsString.h"
+
+#include <stdint.h>
+
+namespace mozilla {
+
+namespace Telemetry {
+class ThreadHangStats;
+} // namespace Telemetry
+
+class BackgroundHangThread;
+class BackgroundHangManager;
+
+/**
+ * The background hang monitor is responsible for detecting and reporting
+ * hangs in main and background threads. A thread registers itself using
+ * the BackgroundHangMonitor object and periodically calls its methods to
+ * inform the hang monitor of the thread's activity. Each thread is given
+ * a thread name, a timeout, and a maximum timeout. If one of the thread's
+ * tasks runs for longer than the timeout duration but shorter than the
+ * maximum timeout, a (transient) hang is reported. On the other hand, if
+ * a task runs for longer than the maximum timeout duration or never
+ * finishes (e.g. in a deadlock), a permahang is reported.
+ *
+ * Tasks are defined arbitrarily, but are typically represented by events
+ * in an event loop -- processing one event is equivalent to running one
+ * task. To ensure responsiveness, tasks in a thread often have a target
+ * running time. This is a good starting point for determining the timeout
+ * and maximum timeout values. For example, the Compositor thread has a
+ * responsiveness goal of 60Hz or 17ms, so a starting timeout could be
+ * 100ms. Considering some platforms (e.g. Android) can terminate the app
+ * when a critical thread hangs for longer than a few seconds, a good
+ * starting maximum timeout is 4 or 5 seconds.
+ *
+ * A thread registers itself through the BackgroundHangMonitor constructor.
+ * Multiple BackgroundHangMonitor objects can be used in one thread. The
+ * constructor without arguments can be used when it is known that the thread
+ * already has a BackgroundHangMonitor registered. When all instances of
+ * BackgroundHangMonitor are destroyed, the thread is unregistered.
+ *
+ * The thread then uses two methods to inform BackgroundHangMonitor of the
+ * thread's activity:
+ *
+ *  > BackgroundHangMonitor::NotifyActivity should be called *before*
+ *    starting a task. The task run time is determined by the interval
+ *    between this call and the next NotifyActivity call.
+ *
+ *  > BackgroundHangMonitor::NotifyWait should be called *before* the
+ *    thread enters a wait state (e.g. to wait for a new event). This
+ *    prevents a waiting thread from being detected as hanging. The wait
+ *    state is automatically cleared at the next NotifyActivity call.
+ *
+ * The following example shows hang monitoring in a simple event loop:
+ *
+ *  void thread_main()
+ *  {
+ *    mozilla::BackgroundHangMonitor hangMonitor("example1", 100, 1000);
+ *    while (!exiting) {
+ *      hangMonitor.NotifyActivity();
+ *      process_next_event();
+ *      hangMonitor.NotifyWait();
+ *      wait_for_next_event();
+ *    }
+ *  }
+ *
+ * The following example shows reentrancy in nested event loops:
+ *
+ *  void thread_main()
+ *  {
+ *    mozilla::BackgroundHangMonitor hangMonitor("example2", 100, 1000);
+ *    while (!exiting) {
+ *      hangMonitor.NotifyActivity();
+ *      process_next_event();
+ *      hangMonitor.NotifyWait();
+ *      wait_for_next_event();
+ *    }
+ *  }
+ *
+ *  void process_next_event()
+ *  {
+ *    mozilla::BackgroundHangMonitor hangMonitor();
+ *    if (is_sync_event) {
+ *      while (!finished_event) {
+ *        hangMonitor.NotifyActivity();
+ *        process_next_event();
+ *        hangMonitor.NotifyWait();
+ *        wait_for_next_event();
+ *      }
+ *    } else {
+ *      process_nonsync_event();
+ *    }
+ *  }
+ */
+class BackgroundHangMonitor
+{
+private:
+  friend BackgroundHangManager;
+
+  RefPtr<BackgroundHangThread> mThread;
+
+  static bool ShouldDisableOnBeta(const nsCString &);
+  static bool DisableOnBeta();
+
+public:
+  static const uint32_t kNoTimeout = 0;
+  enum ThreadType {
+    // For a new BackgroundHangMonitor for thread T, only create a new
+    // monitoring thread for T if one doesn't already exist. If one does,
+    // share that pre-existing monitoring thread.
+    THREAD_SHARED,
+    // For a new BackgroundHangMonitor for thread T, create a new
+    // monitoring thread for T even if there are other, pre-existing
+    // monitoring threads for T.
+    THREAD_PRIVATE
+  };
+
+  /**
+   * ThreadHangStatsIterator is used to iterate through the ThreadHangStats
+   * associated with each active monitored thread. Because of an internal
+   * lock while this object is alive, a thread must use only one instance
+   * of this class at a time and must iterate through the list as fast as
+   * possible. The following example shows using the iterator:
+   *
+   * {
+   *   // Scope the iter variable so it's destroyed as soon as we're done
+   *   BackgroundHangMonitor::ThreadHangStatsIterator iter;
+   *   for (ThreadHangStats* histogram = iter.GetNext();
+   *        histogram; histogram = iter.GetNext()) {
+   *     // Process histogram
+   *   }
+   * }
+   */
+  class ThreadHangStatsIterator : public MonitorAutoLock
+  {
+  private:
+    BackgroundHangThread* mThread;
+
+    ThreadHangStatsIterator(const ThreadHangStatsIterator&);
+    ThreadHangStatsIterator& operator=(const ThreadHangStatsIterator&);
+
+  public:
+    /**
+     * Create an ThreadHangStatsIterator instance and take the internal lock.
+     * Internal lock is released on destruction.
+     */
+    ThreadHangStatsIterator();
+
+    /**
+     * Get the next item in the list; the first call returns the first item.
+     * Returns nullptr at the end of the list.
+     */
+    Telemetry::ThreadHangStats* GetNext();
+  };
+
+  /**
+   * Enable hang monitoring.
+   * Must return before using BackgroundHangMonitor.
+   */
+  static void Startup();
+
+  /**
+   * Disable hang monitoring.
+   * Can be called without destroying all BackgroundHangMonitors first.
+   */
+  static void Shutdown();
+
+  /**
+   * Returns true if BHR is disabled.
+   */
+  static bool IsDisabled();
+
+  /**
+   * Start monitoring hangs for the current thread.
+   *
+   * @param aName Name to identify the thread with
+   * @param aTimeoutMs Amount of time in milliseconds without
+   *  activity before registering a hang
+   * @param aMaxTimeoutMs Amount of time in milliseconds without
+   *  activity before registering a permanent hang
+   * @param aThreadType
+   *  The ThreadType type of monitoring thread that should be created
+   *  for this monitor. See the documentation for ThreadType.
+   */
+  BackgroundHangMonitor(const char* aName,
+                        uint32_t aTimeoutMs,
+                        uint32_t aMaxTimeoutMs,
+                        ThreadType aThreadType = THREAD_SHARED);
+
+  /**
+   * Monitor hangs using an existing monitor
+   * associated with the current thread.
+   */
+  BackgroundHangMonitor();
+
+  /**
+   * Destroys the hang monitor; hang monitoring for a thread stops
+   * when all monitors associated with the thread are destroyed.
+   */
+  ~BackgroundHangMonitor();
+
+  /**
+   * Notify the hang monitor of pending current thread activity.
+   * Call this method before starting an "activity" or after
+   * exiting from a wait state.
+   */
+  void NotifyActivity();
+
+  /**
+   * Notify the hang monitor of current thread wait.
+   * Call this method before entering a wait state; call
+   * NotifyActivity when subsequently exiting the wait state.
+   */
+  void NotifyWait();
+
+  /**
+   * Register an annotator with BHR for the current thread.
+   * @param aAnnotator annotator to register
+   * @return true if the annotator was registered, otherwise false.
+   */
+  static bool RegisterAnnotator(HangMonitor::Annotator& aAnnotator);
+
+  /**
+   * Unregister an annotator that was previously registered via
+   * RegisterAnnotator.
+   * @param aAnnotator annotator to unregister
+   * @return true if there are still remaining annotators registered
+   */
+  static bool UnregisterAnnotator(HangMonitor::Annotator& aAnnotator);
+};
+
+} // namespace mozilla
+
+#endif // mozilla_BackgroundHangMonitor_h
diff --git a/xpcom/threads/HangAnnotations.cpp b/xpcom/threads/HangAnnotations.cpp
new file mode 100644
index 000000000..529b57b8e
--- /dev/null
+++ b/xpcom/threads/HangAnnotations.cpp
@@ -0,0 +1,262 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/HangAnnotations.h"
+
+#include <vector>
+
+#include "MainThreadUtils.h"
+#include "mozilla/DebugOnly.h"
+#include "nsXULAppAPI.h"
+
+namespace mozilla {
+namespace HangMonitor {
+
+// Chrome hang annotators. This can go away once BHR has completely replaced
+// ChromeHangs.
+static StaticAutoPtr<Observer::Annotators> gChromehangAnnotators;
+
+class BrowserHangAnnotations : public HangAnnotations
+{
+public:
+  BrowserHangAnnotations();
+  ~BrowserHangAnnotations();
+
+  void AddAnnotation(const nsAString& aName, const int32_t aData) override;
+  void AddAnnotation(const nsAString& aName, const double aData) override;
+  void AddAnnotation(const nsAString& aName, const nsAString& aData) override;
+  void AddAnnotation(const nsAString& aName, const nsACString& aData) override;
+  void AddAnnotation(const nsAString& aName, const bool aData) override;
+
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const override;
+  bool IsEmpty() const override;
+  UniquePtr<Enumerator> GetEnumerator() override;
+
+  typedef std::pair<nsString, nsString> AnnotationType;
+  typedef std::vector<AnnotationType> VectorType;
+  typedef VectorType::const_iterator IteratorType;
+
+private:
+  VectorType  mAnnotations;
+};
+
+BrowserHangAnnotations::BrowserHangAnnotations()
+{
+  MOZ_COUNT_CTOR(BrowserHangAnnotations);
+}
+
+BrowserHangAnnotations::~BrowserHangAnnotations()
+{
+  MOZ_COUNT_DTOR(BrowserHangAnnotations);
+}
+
+void
+BrowserHangAnnotations::AddAnnotation(const nsAString& aName, const int32_t aData)
+{
+  nsString dataString;
+  dataString.AppendInt(aData);
+  AnnotationType annotation = std::make_pair(nsString(aName), dataString);
+  mAnnotations.push_back(annotation);
+}
+
+void
+BrowserHangAnnotations::AddAnnotation(const nsAString& aName, const double aData)
+{
+  nsString dataString;
+  dataString.AppendFloat(aData);
+  AnnotationType annotation = std::make_pair(nsString(aName), dataString);
+  mAnnotations.push_back(annotation);
+}
+
+void
+BrowserHangAnnotations::AddAnnotation(const nsAString& aName, const nsAString& aData)
+{
+  AnnotationType annotation = std::make_pair(nsString(aName), nsString(aData));
+  mAnnotations.push_back(annotation);
+}
+
+void
+BrowserHangAnnotations::AddAnnotation(const nsAString& aName, const nsACString& aData)
+{
+  nsString dataString;
+  AppendUTF8toUTF16(aData, dataString);
+  AnnotationType annotation = std::make_pair(nsString(aName), dataString);
+  mAnnotations.push_back(annotation);
+}
+
+void
+BrowserHangAnnotations::AddAnnotation(const nsAString& aName, const bool aData)
+{
+  nsString dataString;
+  dataString += aData ? NS_LITERAL_STRING("true") : NS_LITERAL_STRING("false");
+  AnnotationType annotation = std::make_pair(nsString(aName), dataString);
+  mAnnotations.push_back(annotation);
+}
+
+/**
+ * This class itself does not use synchronization but it (and its parent object)
+ * should be protected by mutual exclusion in some way. In Telemetry the chrome
+ * hang data is protected via TelemetryImpl::mHangReportsMutex.
+ */
+class ChromeHangAnnotationEnumerator : public HangAnnotations::Enumerator
+{
+public:
+  explicit ChromeHangAnnotationEnumerator(const BrowserHangAnnotations::VectorType& aAnnotations);
+  ~ChromeHangAnnotationEnumerator();
+
+  virtual bool Next(nsAString& aOutName, nsAString& aOutValue);
+
+private:
+  BrowserHangAnnotations::IteratorType mIterator;
+  BrowserHangAnnotations::IteratorType mEnd;
+};
+
+ChromeHangAnnotationEnumerator::ChromeHangAnnotationEnumerator(
+                          const BrowserHangAnnotations::VectorType& aAnnotations)
+  : mIterator(aAnnotations.begin())
+  , mEnd(aAnnotations.end())
+{
+  MOZ_COUNT_CTOR(ChromeHangAnnotationEnumerator);
+}
+
+ChromeHangAnnotationEnumerator::~ChromeHangAnnotationEnumerator()
+{
+  MOZ_COUNT_DTOR(ChromeHangAnnotationEnumerator);
+}
+
+bool
+ChromeHangAnnotationEnumerator::Next(nsAString& aOutName, nsAString& aOutValue)
+{
+  aOutName.Truncate();
+  aOutValue.Truncate();
+  if (mIterator == mEnd) {
+    return false;
+  }
+  aOutName = mIterator->first;
+  aOutValue = mIterator->second;
+  ++mIterator;
+  return true;
+}
+
+bool
+BrowserHangAnnotations::IsEmpty() const
+{
+  return mAnnotations.empty();
+}
+
+size_t
+BrowserHangAnnotations::SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+{
+  size_t result = sizeof(mAnnotations) +
+                  mAnnotations.capacity() * sizeof(AnnotationType);
+  for (IteratorType i = mAnnotations.begin(), e = mAnnotations.end(); i != e;
+       ++i) {
+    result += i->first.SizeOfExcludingThisIfUnshared(aMallocSizeOf);
+    result += i->second.SizeOfExcludingThisIfUnshared(aMallocSizeOf);
+  }
+
+  return result;
+}
+
+UniquePtr<HangAnnotations::Enumerator>
+BrowserHangAnnotations::GetEnumerator()
+{
+  if (mAnnotations.empty()) {
+    return nullptr;
+  }
+  return MakeUnique<ChromeHangAnnotationEnumerator>(mAnnotations);
+}
+
+namespace Observer {
+
+Annotators::Annotators()
+  : mMutex("HangMonitor::Annotators::mMutex")
+{
+  MOZ_COUNT_CTOR(Annotators);
+}
+
+Annotators::~Annotators()
+{
+  MOZ_ASSERT(mAnnotators.empty());
+  MOZ_COUNT_DTOR(Annotators);
+}
+
+bool
+Annotators::Register(Annotator& aAnnotator)
+{
+  MutexAutoLock lock(mMutex);
+  auto result = mAnnotators.insert(&aAnnotator);
+  return result.second;
+}
+
+bool
+Annotators::Unregister(Annotator& aAnnotator)
+{
+  MutexAutoLock lock(mMutex);
+  DebugOnly<std::set<Annotator*>::size_type> numErased;
+  numErased = mAnnotators.erase(&aAnnotator);
+  MOZ_ASSERT(numErased == 1);
+  return mAnnotators.empty();
+}
+
+UniquePtr<HangAnnotations>
+Annotators::GatherAnnotations()
+{
+  auto annotations = MakeUnique<BrowserHangAnnotations>();
+  { // Scope for lock
+    MutexAutoLock lock(mMutex);
+    for (std::set<Annotator*>::iterator i = mAnnotators.begin(),
+                                        e = mAnnotators.end();
+         i != e; ++i) {
+      (*i)->AnnotateHang(*annotations);
+    }
+  }
+  if (annotations->IsEmpty()) {
+    return nullptr;
+  }
+  return Move(annotations);
+}
+
+} // namespace Observer
+
+void
+RegisterAnnotator(Annotator& aAnnotator)
+{
+  BackgroundHangMonitor::RegisterAnnotator(aAnnotator);
+  // We still register annotators for ChromeHangs
+  if (NS_IsMainThread() &&
+      GeckoProcessType_Default == XRE_GetProcessType()) {
+    if (!gChromehangAnnotators) {
+      gChromehangAnnotators = new Observer::Annotators();
+    }
+    gChromehangAnnotators->Register(aAnnotator);
+  }
+}
+
+void
+UnregisterAnnotator(Annotator& aAnnotator)
+{
+  BackgroundHangMonitor::UnregisterAnnotator(aAnnotator);
+  // We still register annotators for ChromeHangs
+  if (NS_IsMainThread() &&
+      GeckoProcessType_Default == XRE_GetProcessType()) {
+    if (gChromehangAnnotators->Unregister(aAnnotator)) {
+      gChromehangAnnotators = nullptr;
+    }
+  }
+}
+
+UniquePtr<HangAnnotations>
+ChromeHangAnnotatorCallout()
+{
+  if (!gChromehangAnnotators) {
+    return nullptr;
+  }
+  return gChromehangAnnotators->GatherAnnotations();
+}
+
+} // namespace HangMonitor
+} // namespace mozilla
diff --git a/xpcom/threads/HangAnnotations.h b/xpcom/threads/HangAnnotations.h
new file mode 100644
index 000000000..6dddbf4bb
--- /dev/null
+++ b/xpcom/threads/HangAnnotations.h
@@ -0,0 +1,104 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_HangAnnotations_h
+#define mozilla_HangAnnotations_h
+
+#include <set>
+
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/Vector.h"
+#include "nsString.h"
+
+namespace mozilla {
+namespace HangMonitor {
+
+/**
+ * This class declares an abstraction for a data type that encapsulates all
+ * of the annotations being reported by a registered hang Annotator.
+ */
+class HangAnnotations
+{
+public:
+  virtual ~HangAnnotations() {}
+
+  virtual void AddAnnotation(const nsAString& aName, const int32_t aData) = 0;
+  virtual void AddAnnotation(const nsAString& aName, const double aData) = 0;
+  virtual void AddAnnotation(const nsAString& aName, const nsAString& aData) = 0;
+  virtual void AddAnnotation(const nsAString& aName, const nsACString& aData) = 0;
+  virtual void AddAnnotation(const nsAString& aName, const bool aData) = 0;
+
+  class Enumerator
+  {
+  public:
+    virtual ~Enumerator() {}
+    virtual bool Next(nsAString& aOutName, nsAString& aOutValue) = 0;
+  };
+
+  virtual size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const = 0;
+  virtual bool IsEmpty() const = 0;
+  virtual UniquePtr<Enumerator> GetEnumerator() = 0;
+};
+
+typedef UniquePtr<HangAnnotations> HangAnnotationsPtr;
+typedef Vector<HangAnnotationsPtr> HangAnnotationsVector;
+
+class Annotator
+{
+public:
+  /**
+   * NB: This function is always called by the HangMonitor thread.
+   *     Plan accordingly.
+   */
+  virtual void AnnotateHang(HangAnnotations& aAnnotations) = 0;
+};
+
+/**
+ * Registers an Annotator to be called when a hang is detected.
+ * @param aAnnotator Reference to an object that implements the
+ * HangMonitor::Annotator interface.
+ */
+void RegisterAnnotator(Annotator& aAnnotator);
+
+/**
+ * Registers an Annotator that was previously registered via RegisterAnnotator.
+ * @param aAnnotator Reference to an object that implements the
+ * HangMonitor::Annotator interface.
+ */
+void UnregisterAnnotator(Annotator& aAnnotator);
+
+/**
+ * Gathers annotations. This function should be called by ChromeHangs.
+ * @return UniquePtr to HangAnnotations object or nullptr if none.
+ */
+HangAnnotationsPtr ChromeHangAnnotatorCallout();
+
+namespace Observer {
+
+class Annotators
+{
+public:
+  Annotators();
+  ~Annotators();
+
+  bool Register(Annotator& aAnnotator);
+  bool Unregister(Annotator& aAnnotator);
+
+  HangAnnotationsPtr GatherAnnotations();
+
+private:
+  Mutex                mMutex;
+  std::set<Annotator*> mAnnotators;
+};
+
+} // namespace Observer
+
+} // namespace HangMonitor
+} // namespace mozilla
+
+#endif // mozilla_HangAnnotations_h
diff --git a/xpcom/threads/HangMonitor.cpp b/xpcom/threads/HangMonitor.cpp
new file mode 100644
index 000000000..71cc67ca4
--- /dev/null
+++ b/xpcom/threads/HangMonitor.cpp
@@ -0,0 +1,434 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/HangMonitor.h"
+
+#include "mozilla/Atomics.h"
+#include "mozilla/BackgroundHangMonitor.h"
+#include "mozilla/Monitor.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/ProcessedStack.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/UniquePtr.h"
+#include "nsReadableUtils.h"
+#include "mozilla/StackWalk.h"
+#ifdef _WIN64
+#include "mozilla/StackWalk_windows.h"
+#endif
+#include "nsThreadUtils.h"
+#include "nsXULAppAPI.h"
+
+#ifdef MOZ_CRASHREPORTER
+#include "nsExceptionHandler.h"
+#endif
+
+#ifdef XP_WIN
+#include <windows.h>
+#endif
+
+#if defined(MOZ_ENABLE_PROFILER_SPS) && defined(MOZ_PROFILING) && defined(XP_WIN)
+  #define REPORT_CHROME_HANGS
+#endif
+
+namespace mozilla {
+namespace HangMonitor {
+
+/**
+ * A flag which may be set from within a debugger to disable the hang
+ * monitor.
+ */
+volatile bool gDebugDisableHangMonitor = false;
+
+const char kHangMonitorPrefName[] = "hangmonitor.timeout";
+
+#ifdef REPORT_CHROME_HANGS
+const char kTelemetryPrefName[] = "toolkit.telemetry.enabled";
+#endif
+
+// Monitor protects gShutdown and gTimeout, but not gTimestamp which rely on
+// being atomically set by the processor; synchronization doesn't really matter
+// in this use case.
+Monitor* gMonitor;
+
+// The timeout preference, in seconds.
+int32_t gTimeout;
+
+PRThread* gThread;
+
+// Set when shutdown begins to signal the thread to exit immediately.
+bool gShutdown;
+
+// The timestamp of the last event notification, or PR_INTERVAL_NO_WAIT if
+// we're currently not processing events.
+Atomic<PRIntervalTime> gTimestamp(PR_INTERVAL_NO_WAIT);
+
+#ifdef REPORT_CHROME_HANGS
+// Main thread ID used in reporting chrome hangs under Windows
+static HANDLE winMainThreadHandle = nullptr;
+
+// Default timeout for reporting chrome hangs to Telemetry (5 seconds)
+static const int32_t DEFAULT_CHROME_HANG_INTERVAL = 5;
+
+// Maximum number of PCs to gather from the stack
+static const int32_t MAX_CALL_STACK_PCS = 400;
+#endif
+
+// PrefChangedFunc
+void
+PrefChanged(const char*, void*)
+{
+  int32_t newval = Preferences::GetInt(kHangMonitorPrefName);
+#ifdef REPORT_CHROME_HANGS
+  // Monitor chrome hangs on the profiling branch if Telemetry enabled
+  if (newval == 0) {
+    bool telemetryEnabled = Preferences::GetBool(kTelemetryPrefName);
+    if (telemetryEnabled) {
+      newval = DEFAULT_CHROME_HANG_INTERVAL;
+    }
+  }
+#endif
+  MonitorAutoLock lock(*gMonitor);
+  if (newval != gTimeout) {
+    gTimeout = newval;
+    lock.Notify();
+  }
+}
+
+void
+Crash()
+{
+  if (gDebugDisableHangMonitor) {
+    return;
+  }
+
+#ifdef XP_WIN
+  if (::IsDebuggerPresent()) {
+    return;
+  }
+#endif
+
+#ifdef MOZ_CRASHREPORTER
+  // If you change this, you must also deal with the threadsafety of AnnotateCrashReport in
+  // non-chrome processes!
+  if (GeckoProcessType_Default == XRE_GetProcessType()) {
+    CrashReporter::AnnotateCrashReport(NS_LITERAL_CSTRING("Hang"),
+                                       NS_LITERAL_CSTRING("1"));
+  }
+#endif
+
+  NS_RUNTIMEABORT("HangMonitor triggered");
+}
+
+#ifdef REPORT_CHROME_HANGS
+
+static void
+ChromeStackWalker(uint32_t aFrameNumber, void* aPC, void* aSP, void* aClosure)
+{
+  MOZ_ASSERT(aClosure);
+  std::vector<uintptr_t>* stack =
+    static_cast<std::vector<uintptr_t>*>(aClosure);
+  if (stack->size() == MAX_CALL_STACK_PCS) {
+    return;
+  }
+  MOZ_ASSERT(stack->size() < MAX_CALL_STACK_PCS);
+  stack->push_back(reinterpret_cast<uintptr_t>(aPC));
+}
+
+static void
+GetChromeHangReport(Telemetry::ProcessedStack& aStack,
+                    int32_t& aSystemUptime,
+                    int32_t& aFirefoxUptime)
+{
+  MOZ_ASSERT(winMainThreadHandle);
+
+  // The thread we're about to suspend might have the alloc lock
+  // so allocate ahead of time
+  std::vector<uintptr_t> rawStack;
+  rawStack.reserve(MAX_CALL_STACK_PCS);
+
+  // Workaround possible deadlock where the main thread is running a
+  // long-standing JS job, and happens to be in the JIT allocator when we
+  // suspend it. Since, on win 64, this requires holding a process lock that
+  // MozStackWalk requires, take this "workaround lock" to avoid deadlock.
+#ifdef _WIN64
+  AcquireStackWalkWorkaroundLock();
+#endif
+  DWORD ret = ::SuspendThread(winMainThreadHandle);
+  bool suspended = false;
+  if (ret != -1) {
+    // SuspendThread is asynchronous, so the thread may still be running. Use
+    // GetThreadContext to ensure it's really suspended.
+    // See https://blogs.msdn.microsoft.com/oldnewthing/20150205-00/?p=44743.
+    CONTEXT context;
+    context.ContextFlags = CONTEXT_CONTROL;
+    if (::GetThreadContext(winMainThreadHandle, &context)) {
+      suspended = true;
+    }
+  }
+
+#ifdef _WIN64
+  ReleaseStackWalkWorkaroundLock();
+#endif
+
+  if (!suspended) {
+    if (ret != -1) {
+      MOZ_ALWAYS_TRUE(::ResumeThread(winMainThreadHandle) != DWORD(-1));
+    }
+    return;
+  }
+
+  MozStackWalk(ChromeStackWalker, /* skipFrames */ 0, /* maxFrames */ 0,
+               reinterpret_cast<void*>(&rawStack),
+               reinterpret_cast<uintptr_t>(winMainThreadHandle), nullptr);
+  ret = ::ResumeThread(winMainThreadHandle);
+  if (ret == -1) {
+    return;
+  }
+  aStack = Telemetry::GetStackAndModules(rawStack);
+
+  // Record system uptime (in minutes) at the time of the hang
+  aSystemUptime = ((GetTickCount() / 1000) - (gTimeout * 2)) / 60;
+
+  // Record Firefox uptime (in minutes) at the time of the hang
+  bool error;
+  TimeStamp processCreation = TimeStamp::ProcessCreation(error);
+  if (!error) {
+    TimeDuration td = TimeStamp::Now() - processCreation;
+    aFirefoxUptime = (static_cast<int32_t>(td.ToSeconds()) - (gTimeout * 2)) / 60;
+  } else {
+    aFirefoxUptime = -1;
+  }
+}
+
+#endif
+
+void
+ThreadMain(void*)
+{
+  PR_SetCurrentThreadName("Hang Monitor");
+
+  MonitorAutoLock lock(*gMonitor);
+
+  // In order to avoid issues with the hang monitor incorrectly triggering
+  // during a general system stop such as sleeping, the monitor thread must
+  // run twice to trigger hang protection.
+  PRIntervalTime lastTimestamp = 0;
+  int waitCount = 0;
+
+#ifdef REPORT_CHROME_HANGS
+  Telemetry::ProcessedStack stack;
+  int32_t systemUptime = -1;
+  int32_t firefoxUptime = -1;
+  UniquePtr<HangAnnotations> annotations;
+#endif
+
+  while (true) {
+    if (gShutdown) {
+      return; // Exit the thread
+    }
+
+    // avoid rereading the volatile value in this loop
+    PRIntervalTime timestamp = gTimestamp;
+
+    PRIntervalTime now = PR_IntervalNow();
+
+    if (timestamp != PR_INTERVAL_NO_WAIT &&
+        now < timestamp) {
+      // 32-bit overflow, reset for another waiting period
+      timestamp = 1; // lowest legal PRInterval value
+    }
+
+    if (timestamp != PR_INTERVAL_NO_WAIT &&
+        timestamp == lastTimestamp &&
+        gTimeout > 0) {
+      ++waitCount;
+#ifdef REPORT_CHROME_HANGS
+      // Capture the chrome-hang stack + Firefox & system uptimes after
+      // the minimum hang duration has been reached (not when the hang ends)
+      if (waitCount == 2) {
+        GetChromeHangReport(stack, systemUptime, firefoxUptime);
+        annotations = ChromeHangAnnotatorCallout();
+      }
+#else
+      // This is the crash-on-hang feature.
+      // See bug 867313 for the quirk in the waitCount comparison
+      if (waitCount >= 2) {
+        int32_t delay =
+          int32_t(PR_IntervalToSeconds(now - timestamp));
+        if (delay >= gTimeout) {
+          MonitorAutoUnlock unlock(*gMonitor);
+          Crash();
+        }
+      }
+#endif
+    } else {
+#ifdef REPORT_CHROME_HANGS
+      if (waitCount >= 2) {
+        uint32_t hangDuration = PR_IntervalToSeconds(now - lastTimestamp);
+        Telemetry::RecordChromeHang(hangDuration, stack, systemUptime,
+                                    firefoxUptime, Move(annotations));
+        stack.Clear();
+      }
+#endif
+      lastTimestamp = timestamp;
+      waitCount = 0;
+    }
+
+    PRIntervalTime timeout;
+    if (gTimeout <= 0) {
+      timeout = PR_INTERVAL_NO_TIMEOUT;
+    } else {
+      timeout = PR_MillisecondsToInterval(gTimeout * 500);
+    }
+    lock.Wait(timeout);
+  }
+}
+
+void
+Startup()
+{
+  if (GeckoProcessType_Default != XRE_GetProcessType() &&
+      GeckoProcessType_Content != XRE_GetProcessType()) {
+    return;
+  }
+
+  MOZ_ASSERT(!gMonitor, "Hang monitor already initialized");
+  gMonitor = new Monitor("HangMonitor");
+
+  Preferences::RegisterCallback(PrefChanged, kHangMonitorPrefName, nullptr);
+  PrefChanged(nullptr, nullptr);
+
+#ifdef REPORT_CHROME_HANGS
+  Preferences::RegisterCallback(PrefChanged, kTelemetryPrefName, nullptr);
+  winMainThreadHandle =
+    OpenThread(THREAD_ALL_ACCESS, FALSE, GetCurrentThreadId());
+  if (!winMainThreadHandle) {
+    return;
+  }
+#endif
+
+  // Don't actually start measuring hangs until we hit the main event loop.
+  // This potentially misses a small class of really early startup hangs,
+  // but avoids dealing with some xpcshell tests and other situations which
+  // start XPCOM but don't ever start the event loop.
+  Suspend();
+
+  gThread = PR_CreateThread(PR_USER_THREAD,
+                            ThreadMain,
+                            nullptr, PR_PRIORITY_LOW, PR_GLOBAL_THREAD,
+                            PR_JOINABLE_THREAD, 0);
+}
+
+void
+Shutdown()
+{
+  if (GeckoProcessType_Default != XRE_GetProcessType() &&
+      GeckoProcessType_Content != XRE_GetProcessType()) {
+    return;
+  }
+
+  MOZ_ASSERT(gMonitor, "Hang monitor not started");
+
+  {
+    // Scope the lock we're going to delete later
+    MonitorAutoLock lock(*gMonitor);
+    gShutdown = true;
+    lock.Notify();
+  }
+
+  // thread creation could theoretically fail
+  if (gThread) {
+    PR_JoinThread(gThread);
+    gThread = nullptr;
+  }
+
+  delete gMonitor;
+  gMonitor = nullptr;
+}
+
+static bool
+IsUIMessageWaiting()
+{
+#ifndef XP_WIN
+  return false;
+#else
+#define NS_WM_IMEFIRST WM_IME_SETCONTEXT
+#define NS_WM_IMELAST  WM_IME_KEYUP
+  BOOL haveUIMessageWaiting = FALSE;
+  MSG msg;
+  haveUIMessageWaiting |= ::PeekMessageW(&msg, nullptr, WM_KEYFIRST,
+                                         WM_IME_KEYLAST, PM_NOREMOVE);
+  haveUIMessageWaiting |= ::PeekMessageW(&msg, nullptr, NS_WM_IMEFIRST,
+                                         NS_WM_IMELAST, PM_NOREMOVE);
+  haveUIMessageWaiting |= ::PeekMessageW(&msg, nullptr, WM_MOUSEFIRST,
+                                         WM_MOUSELAST, PM_NOREMOVE);
+  return haveUIMessageWaiting;
+#endif
+}
+
+void
+NotifyActivity(ActivityType aActivityType)
+{
+  MOZ_ASSERT(NS_IsMainThread(),
+             "HangMonitor::Notify called from off the main thread.");
+
+  // Determine the activity type more specifically
+  if (aActivityType == kGeneralActivity) {
+    aActivityType = IsUIMessageWaiting() ? kActivityUIAVail :
+                                           kActivityNoUIAVail;
+  }
+
+  // Calculate the cumulative amount of lag time since the last UI message
+  static uint32_t cumulativeUILagMS = 0;
+  switch (aActivityType) {
+    case kActivityNoUIAVail:
+      cumulativeUILagMS = 0;
+      break;
+    case kActivityUIAVail:
+    case kUIActivity:
+      if (gTimestamp != PR_INTERVAL_NO_WAIT) {
+        cumulativeUILagMS += PR_IntervalToMilliseconds(PR_IntervalNow() -
+                                                       gTimestamp);
+      }
+      break;
+    default:
+      break;
+  }
+
+  // This is not a locked activity because PRTimeStamp is a 32-bit quantity
+  // which can be read/written atomically, and we don't want to pay locking
+  // penalties here.
+  gTimestamp = PR_IntervalNow();
+
+  // If we have UI activity we should reset the timer and report it
+  if (aActivityType == kUIActivity) {
+    mozilla::Telemetry::Accumulate(mozilla::Telemetry::EVENTLOOP_UI_ACTIVITY_EXP_MS,
+                                     cumulativeUILagMS);
+    cumulativeUILagMS = 0;
+  }
+
+  if (gThread && !gShutdown) {
+    mozilla::BackgroundHangMonitor().NotifyActivity();
+  }
+}
+
+void
+Suspend()
+{
+  MOZ_ASSERT(NS_IsMainThread(),
+             "HangMonitor::Suspend called from off the main thread.");
+
+  // Because gTimestamp changes this resets the wait count.
+  gTimestamp = PR_INTERVAL_NO_WAIT;
+
+  if (gThread && !gShutdown) {
+    mozilla::BackgroundHangMonitor().NotifyWait();
+  }
+}
+
+} // namespace HangMonitor
+} // namespace mozilla
diff --git a/xpcom/threads/HangMonitor.h b/xpcom/threads/HangMonitor.h
new file mode 100644
index 000000000..fd0e6ff83
--- /dev/null
+++ b/xpcom/threads/HangMonitor.h
@@ -0,0 +1,58 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_HangMonitor_h
+#define mozilla_HangMonitor_h
+
+namespace mozilla {
+namespace HangMonitor {
+
+/**
+ * Signifies the type of activity in question
+*/
+enum ActivityType
+{
+  /* There is activity and it is known to be UI related activity. */
+  kUIActivity,
+
+  /* There is non UI activity and no UI activity is pending */
+  kActivityNoUIAVail,
+
+  /* There is non UI activity and UI activity is known to be pending */
+  kActivityUIAVail,
+
+  /* There is non UI activity and UI activity pending is unknown */
+  kGeneralActivity
+};
+
+/**
+ * Start monitoring hangs. Should be called by the XPCOM startup process only.
+ */
+void Startup();
+
+/**
+ * Stop monitoring hangs and join the thread.
+ */
+void Shutdown();
+
+/**
+ * Notify the hang monitor of activity which will reset its internal timer.
+ *
+ * @param activityType The type of activity being reported.
+ * @see ActivityType
+ */
+void NotifyActivity(ActivityType activityType = kGeneralActivity);
+
+/*
+ * Notify the hang monitor that the browser is now idle and no detection should
+ * be done.
+ */
+void Suspend();
+
+} // namespace HangMonitor
+} // namespace mozilla
+
+#endif // mozilla_HangMonitor_h
diff --git a/xpcom/threads/LazyIdleThread.cpp b/xpcom/threads/LazyIdleThread.cpp
new file mode 100644
index 000000000..527cc6819
--- /dev/null
+++ b/xpcom/threads/LazyIdleThread.cpp
@@ -0,0 +1,624 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "LazyIdleThread.h"
+
+#include "nsIObserverService.h"
+
+#include "GeckoProfiler.h"
+#include "nsComponentManagerUtils.h"
+#include "nsIIdlePeriod.h"
+#include "nsServiceManagerUtils.h"
+#include "nsThreadUtils.h"
+#include "mozilla/Services.h"
+
+#ifdef DEBUG
+#define ASSERT_OWNING_THREAD()                                                 \
+  PR_BEGIN_MACRO                                                               \
+    nsIThread* currentThread = NS_GetCurrentThread();                          \
+    if (currentThread) {                                                       \
+      nsCOMPtr<nsISupports> current(do_QueryInterface(currentThread));         \
+      nsCOMPtr<nsISupports> test(do_QueryInterface(mOwningThread));            \
+      MOZ_ASSERT(current == test, "Wrong thread!");                            \
+    }                                                                          \
+  PR_END_MACRO
+#else
+#define ASSERT_OWNING_THREAD() /* nothing */
+#endif
+
+namespace mozilla {
+
+LazyIdleThread::LazyIdleThread(uint32_t aIdleTimeoutMS,
+                               const nsCSubstring& aName,
+                               ShutdownMethod aShutdownMethod,
+                               nsIObserver* aIdleObserver)
+  : mMutex("LazyIdleThread::mMutex")
+  , mOwningThread(NS_GetCurrentThread())
+  , mIdleObserver(aIdleObserver)
+  , mQueuedRunnables(nullptr)
+  , mIdleTimeoutMS(aIdleTimeoutMS)
+  , mPendingEventCount(0)
+  , mIdleNotificationCount(0)
+  , mShutdownMethod(aShutdownMethod)
+  , mShutdown(false)
+  , mThreadIsShuttingDown(false)
+  , mIdleTimeoutEnabled(true)
+  , mName(aName)
+{
+  MOZ_ASSERT(mOwningThread, "Need owning thread!");
+}
+
+LazyIdleThread::~LazyIdleThread()
+{
+  ASSERT_OWNING_THREAD();
+
+  Shutdown();
+}
+
+void
+LazyIdleThread::SetWeakIdleObserver(nsIObserver* aObserver)
+{
+  ASSERT_OWNING_THREAD();
+
+  if (mShutdown) {
+    NS_WARNING_ASSERTION(!aObserver,
+                         "Setting an observer after Shutdown was called!");
+    return;
+  }
+
+  mIdleObserver = aObserver;
+}
+
+void
+LazyIdleThread::DisableIdleTimeout()
+{
+  ASSERT_OWNING_THREAD();
+  if (!mIdleTimeoutEnabled) {
+    return;
+  }
+  mIdleTimeoutEnabled = false;
+
+  if (mIdleTimer && NS_FAILED(mIdleTimer->Cancel())) {
+    NS_WARNING("Failed to cancel timer!");
+  }
+
+  MutexAutoLock lock(mMutex);
+
+  // Pretend we have a pending event to keep the idle timer from firing.
+  MOZ_ASSERT(mPendingEventCount < UINT32_MAX, "Way too many!");
+  mPendingEventCount++;
+}
+
+void
+LazyIdleThread::EnableIdleTimeout()
+{
+  ASSERT_OWNING_THREAD();
+  if (mIdleTimeoutEnabled) {
+    return;
+  }
+  mIdleTimeoutEnabled = true;
+
+  {
+    MutexAutoLock lock(mMutex);
+
+    MOZ_ASSERT(mPendingEventCount, "Mismatched calls to observer methods!");
+    --mPendingEventCount;
+  }
+
+  if (mThread) {
+    nsCOMPtr<nsIRunnable> runnable(new Runnable());
+    if (NS_FAILED(Dispatch(runnable.forget(), NS_DISPATCH_NORMAL))) {
+      NS_WARNING("Failed to dispatch!");
+    }
+  }
+}
+
+void
+LazyIdleThread::PreDispatch()
+{
+  MutexAutoLock lock(mMutex);
+
+  MOZ_ASSERT(mPendingEventCount < UINT32_MAX, "Way too many!");
+  mPendingEventCount++;
+}
+
+nsresult
+LazyIdleThread::EnsureThread()
+{
+  ASSERT_OWNING_THREAD();
+
+  if (mShutdown) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (mThread) {
+    return NS_OK;
+  }
+
+  MOZ_ASSERT(!mPendingEventCount, "Shouldn't have events yet!");
+  MOZ_ASSERT(!mIdleNotificationCount, "Shouldn't have idle events yet!");
+  MOZ_ASSERT(!mIdleTimer, "Should have killed this long ago!");
+  MOZ_ASSERT(!mThreadIsShuttingDown, "Should have cleared that!");
+
+  nsresult rv;
+
+  if (mShutdownMethod == AutomaticShutdown && NS_IsMainThread()) {
+    nsCOMPtr<nsIObserverService> obs =
+      do_GetService(NS_OBSERVERSERVICE_CONTRACTID, &rv);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    rv = obs->AddObserver(this, "xpcom-shutdown-threads", false);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+  mIdleTimer = do_CreateInstance(NS_TIMER_CONTRACTID, &rv);
+  if (NS_WARN_IF(!mIdleTimer)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  nsCOMPtr<nsIRunnable> runnable =
+    NewRunnableMethod(this, &LazyIdleThread::InitThread);
+  if (NS_WARN_IF(!runnable)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  rv = NS_NewThread(getter_AddRefs(mThread), runnable);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  return NS_OK;
+}
+
+void
+LazyIdleThread::InitThread()
+{
+  char aLocal;
+  profiler_register_thread(mName.get(), &aLocal);
+
+  PR_SetCurrentThreadName(mName.get());
+
+  // Happens on mThread but mThread may not be set yet...
+
+  nsCOMPtr<nsIThreadInternal> thread(do_QueryInterface(NS_GetCurrentThread()));
+  MOZ_ASSERT(thread, "This should always succeed!");
+
+  if (NS_FAILED(thread->SetObserver(this))) {
+    NS_WARNING("Failed to set thread observer!");
+  }
+}
+
+void
+LazyIdleThread::CleanupThread()
+{
+  nsCOMPtr<nsIThreadInternal> thread(do_QueryInterface(NS_GetCurrentThread()));
+  MOZ_ASSERT(thread, "This should always succeed!");
+
+  if (NS_FAILED(thread->SetObserver(nullptr))) {
+    NS_WARNING("Failed to set thread observer!");
+  }
+
+  {
+    MutexAutoLock lock(mMutex);
+
+    MOZ_ASSERT(!mThreadIsShuttingDown, "Shouldn't be true ever!");
+    mThreadIsShuttingDown = true;
+  }
+
+  profiler_unregister_thread();
+}
+
+void
+LazyIdleThread::ScheduleTimer()
+{
+  ASSERT_OWNING_THREAD();
+
+  bool shouldSchedule;
+  {
+    MutexAutoLock lock(mMutex);
+
+    MOZ_ASSERT(mIdleNotificationCount, "Should have at least one!");
+    --mIdleNotificationCount;
+
+    shouldSchedule = !mIdleNotificationCount && !mPendingEventCount;
+  }
+
+  if (mIdleTimer) {
+    if (NS_FAILED(mIdleTimer->Cancel())) {
+      NS_WARNING("Failed to cancel timer!");
+    }
+
+    if (shouldSchedule &&
+        NS_FAILED(mIdleTimer->InitWithCallback(this, mIdleTimeoutMS,
+                                               nsITimer::TYPE_ONE_SHOT))) {
+      NS_WARNING("Failed to schedule timer!");
+    }
+  }
+}
+
+nsresult
+LazyIdleThread::ShutdownThread()
+{
+  ASSERT_OWNING_THREAD();
+
+  // Before calling Shutdown() on the real thread we need to put a queue in
+  // place in case a runnable is posted to the thread while it's in the
+  // process of shutting down. This will be our queue.
+  AutoTArray<nsCOMPtr<nsIRunnable>, 10> queuedRunnables;
+
+  nsresult rv;
+
+  // Make sure to cancel the shutdown timer before spinning the event loop
+  // during |mThread->Shutdown()| below. Otherwise the timer might fire and we
+  // could reenter here.
+  if (mIdleTimer) {
+    rv = mIdleTimer->Cancel();
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    mIdleTimer = nullptr;
+  }
+
+  if (mThread) {
+    if (mShutdownMethod == AutomaticShutdown && NS_IsMainThread()) {
+      nsCOMPtr<nsIObserverService> obs =
+        mozilla::services::GetObserverService();
+      NS_WARNING_ASSERTION(obs, "Failed to get observer service!");
+
+      if (obs &&
+          NS_FAILED(obs->RemoveObserver(this, "xpcom-shutdown-threads"))) {
+        NS_WARNING("Failed to remove observer!");
+      }
+    }
+
+    if (mIdleObserver) {
+      mIdleObserver->Observe(static_cast<nsIThread*>(this), IDLE_THREAD_TOPIC,
+                             nullptr);
+    }
+
+#ifdef DEBUG
+    {
+      MutexAutoLock lock(mMutex);
+      MOZ_ASSERT(!mThreadIsShuttingDown, "Huh?!");
+    }
+#endif
+
+    nsCOMPtr<nsIRunnable> runnable =
+      NewRunnableMethod(this, &LazyIdleThread::CleanupThread);
+    if (NS_WARN_IF(!runnable)) {
+      return NS_ERROR_UNEXPECTED;
+    }
+
+    PreDispatch();
+
+    rv = mThread->Dispatch(runnable.forget(), NS_DISPATCH_NORMAL);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    // Put the temporary queue in place before calling Shutdown().
+    mQueuedRunnables = &queuedRunnables;
+
+    if (NS_FAILED(mThread->Shutdown())) {
+      NS_ERROR("Failed to shutdown the thread!");
+    }
+
+    // Now unset the queue.
+    mQueuedRunnables = nullptr;
+
+    mThread = nullptr;
+
+    {
+      MutexAutoLock lock(mMutex);
+
+      MOZ_ASSERT(!mPendingEventCount, "Huh?!");
+      MOZ_ASSERT(!mIdleNotificationCount, "Huh?!");
+      MOZ_ASSERT(mThreadIsShuttingDown, "Huh?!");
+      mThreadIsShuttingDown = false;
+    }
+  }
+
+  // If our temporary queue has any runnables then we need to dispatch them.
+  if (queuedRunnables.Length()) {
+    // If the thread manager has gone away then these runnables will never run.
+    if (mShutdown) {
+      NS_ERROR("Runnables dispatched to LazyIdleThread will never run!");
+      return NS_OK;
+    }
+
+    // Re-dispatch the queued runnables.
+    for (uint32_t index = 0; index < queuedRunnables.Length(); index++) {
+      nsCOMPtr<nsIRunnable> runnable;
+      runnable.swap(queuedRunnables[index]);
+      MOZ_ASSERT(runnable, "Null runnable?!");
+
+      if (NS_FAILED(Dispatch(runnable.forget(), NS_DISPATCH_NORMAL))) {
+        NS_ERROR("Failed to re-dispatch queued runnable!");
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+void
+LazyIdleThread::SelfDestruct()
+{
+  MOZ_ASSERT(mRefCnt == 1, "Bad refcount!");
+  delete this;
+}
+
+NS_IMPL_ADDREF(LazyIdleThread)
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+LazyIdleThread::Release()
+{
+  nsrefcnt count = --mRefCnt;
+  NS_LOG_RELEASE(this, count, "LazyIdleThread");
+
+  if (!count) {
+    // Stabilize refcount.
+    mRefCnt = 1;
+
+    nsCOMPtr<nsIRunnable> runnable =
+      NewNonOwningRunnableMethod(this, &LazyIdleThread::SelfDestruct);
+    NS_WARNING_ASSERTION(runnable, "Couldn't make runnable!");
+
+    if (NS_FAILED(NS_DispatchToCurrentThread(runnable))) {
+      MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
+      // The only way this could fail is if we're in shutdown, and in that case
+      // threads should have been joined already. Deleting here isn't dangerous
+      // anymore because we won't spin the event loop waiting to join the
+      // thread.
+      SelfDestruct();
+    }
+  }
+
+  return count;
+}
+
+NS_IMPL_QUERY_INTERFACE(LazyIdleThread, nsIThread,
+                        nsIEventTarget,
+                        nsITimerCallback,
+                        nsIThreadObserver,
+                        nsIObserver)
+
+NS_IMETHODIMP
+LazyIdleThread::DispatchFromScript(nsIRunnable* aEvent, uint32_t aFlags)
+{
+  nsCOMPtr<nsIRunnable> event(aEvent);
+  return Dispatch(event.forget(), aFlags);
+}
+
+NS_IMETHODIMP
+LazyIdleThread::Dispatch(already_AddRefed<nsIRunnable> aEvent,
+                         uint32_t aFlags)
+{
+  ASSERT_OWNING_THREAD();
+  nsCOMPtr<nsIRunnable> event(aEvent); // avoid leaks
+
+  // LazyIdleThread can't always support synchronous dispatch currently.
+  if (NS_WARN_IF(aFlags != NS_DISPATCH_NORMAL)) {
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  if (NS_WARN_IF(mShutdown)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  // If our thread is shutting down then we can't actually dispatch right now.
+  // Queue this runnable for later.
+  if (UseRunnableQueue()) {
+    mQueuedRunnables->AppendElement(event);
+    return NS_OK;
+  }
+
+  nsresult rv = EnsureThread();
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  PreDispatch();
+
+  return mThread->Dispatch(event.forget(), aFlags);
+}
+
+NS_IMETHODIMP
+LazyIdleThread::DelayedDispatch(already_AddRefed<nsIRunnable>, uint32_t)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+LazyIdleThread::IsOnCurrentThread(bool* aIsOnCurrentThread)
+{
+  if (mThread) {
+    return mThread->IsOnCurrentThread(aIsOnCurrentThread);
+  }
+
+  *aIsOnCurrentThread = false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+LazyIdleThread::GetPRThread(PRThread** aPRThread)
+{
+  if (mThread) {
+    return mThread->GetPRThread(aPRThread);
+  }
+
+  *aPRThread = nullptr;
+  return NS_ERROR_NOT_AVAILABLE;
+}
+
+NS_IMETHODIMP
+LazyIdleThread::GetCanInvokeJS(bool* aCanInvokeJS)
+{
+  *aCanInvokeJS = false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+LazyIdleThread::SetCanInvokeJS(bool aCanInvokeJS)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+LazyIdleThread::AsyncShutdown()
+{
+  ASSERT_OWNING_THREAD();
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+LazyIdleThread::Shutdown()
+{
+  ASSERT_OWNING_THREAD();
+
+  mShutdown = true;
+
+  nsresult rv = ShutdownThread();
+  MOZ_ASSERT(!mThread, "Should have destroyed this by now!");
+
+  mIdleObserver = nullptr;
+
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+LazyIdleThread::HasPendingEvents(bool* aHasPendingEvents)
+{
+  // This is only supposed to be called from the thread itself so it's not
+  // implemented here.
+  NS_NOTREACHED("Shouldn't ever call this!");
+  return NS_ERROR_UNEXPECTED;
+}
+
+NS_IMETHODIMP
+LazyIdleThread::IdleDispatch(already_AddRefed<nsIRunnable> aEvent)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+LazyIdleThread::RegisterIdlePeriod(already_AddRefed<nsIIdlePeriod> aIdlePeriod)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+LazyIdleThread::ProcessNextEvent(bool aMayWait,
+                                 bool* aEventWasProcessed)
+{
+  // This is only supposed to be called from the thread itself so it's not
+  // implemented here.
+  NS_NOTREACHED("Shouldn't ever call this!");
+  return NS_ERROR_UNEXPECTED;
+}
+
+NS_IMETHODIMP
+LazyIdleThread::Notify(nsITimer* aTimer)
+{
+  ASSERT_OWNING_THREAD();
+
+  {
+    MutexAutoLock lock(mMutex);
+
+    if (mPendingEventCount || mIdleNotificationCount) {
+      // Another event was scheduled since this timer was set. Don't do
+      // anything and wait for the timer to fire again.
+      return NS_OK;
+    }
+  }
+
+  nsresult rv = ShutdownThread();
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+LazyIdleThread::OnDispatchedEvent(nsIThreadInternal* /*aThread */)
+{
+  MOZ_ASSERT(NS_GetCurrentThread() == mOwningThread, "Wrong thread!");
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+LazyIdleThread::OnProcessNextEvent(nsIThreadInternal* /* aThread */,
+                                   bool /* aMayWait */)
+{
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+LazyIdleThread::AfterProcessNextEvent(nsIThreadInternal* /* aThread */,
+                                      bool aEventWasProcessed)
+{
+  bool shouldNotifyIdle;
+  {
+    MutexAutoLock lock(mMutex);
+
+    if (aEventWasProcessed) {
+      MOZ_ASSERT(mPendingEventCount, "Mismatched calls to observer methods!");
+      --mPendingEventCount;
+    }
+
+    if (mThreadIsShuttingDown) {
+      // We're shutting down, no need to fire any timer.
+      return NS_OK;
+    }
+
+    shouldNotifyIdle = !mPendingEventCount;
+    if (shouldNotifyIdle) {
+      MOZ_ASSERT(mIdleNotificationCount < UINT32_MAX, "Way too many!");
+      mIdleNotificationCount++;
+    }
+  }
+
+  if (shouldNotifyIdle) {
+    nsCOMPtr<nsIRunnable> runnable =
+      NewRunnableMethod(this, &LazyIdleThread::ScheduleTimer);
+    if (NS_WARN_IF(!runnable)) {
+      return NS_ERROR_UNEXPECTED;
+    }
+
+    nsresult rv = mOwningThread->Dispatch(runnable.forget(), NS_DISPATCH_NORMAL);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+LazyIdleThread::Observe(nsISupports* /* aSubject */,
+                        const char*  aTopic,
+                        const char16_t* /* aData */)
+{
+  MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
+  MOZ_ASSERT(mShutdownMethod == AutomaticShutdown,
+             "Should not receive notifications if not AutomaticShutdown!");
+  MOZ_ASSERT(!strcmp("xpcom-shutdown-threads", aTopic), "Bad topic!");
+
+  Shutdown();
+  return NS_OK;
+}
+
+} // namespace mozilla
diff --git a/xpcom/threads/LazyIdleThread.h b/xpcom/threads/LazyIdleThread.h
new file mode 100644
index 000000000..6bf8e8e81
--- /dev/null
+++ b/xpcom/threads/LazyIdleThread.h
@@ -0,0 +1,226 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_lazyidlethread_h__
+#define mozilla_lazyidlethread_h__
+
+#ifndef MOZILLA_INTERNAL_API
+#error "This header is only usable from within libxul (MOZILLA_INTERNAL_API)."
+#endif
+
+#include "nsIObserver.h"
+#include "nsIThreadInternal.h"
+#include "nsITimer.h"
+
+#include "mozilla/Mutex.h"
+#include "nsCOMPtr.h"
+#include "nsTArray.h"
+#include "nsString.h"
+#include "mozilla/Attributes.h"
+
+#define IDLE_THREAD_TOPIC "thread-shutting-down"
+
+namespace mozilla {
+
+/**
+ * This class provides a basic event target that creates its thread lazily and
+ * destroys its thread after a period of inactivity. It may be created on any
+ * thread but it may only be used from the thread on which it is created. If it
+ * is created on the main thread then it will automatically join its thread on
+ * XPCOM shutdown using the Observer Service.
+ */
+class LazyIdleThread final
+  : public nsIThread
+  , public nsITimerCallback
+  , public nsIThreadObserver
+  , public nsIObserver
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIEVENTTARGET
+  NS_DECL_NSITHREAD
+  NS_DECL_NSITIMERCALLBACK
+  NS_DECL_NSITHREADOBSERVER
+  NS_DECL_NSIOBSERVER
+  using nsIEventTarget::Dispatch;
+
+  enum ShutdownMethod
+  {
+    AutomaticShutdown = 0,
+    ManualShutdown
+  };
+
+  /**
+   * Create a new LazyIdleThread that will destroy its thread after the given
+   * number of milliseconds.
+   */
+  LazyIdleThread(uint32_t aIdleTimeoutMS,
+                 const nsCSubstring& aName,
+                 ShutdownMethod aShutdownMethod = AutomaticShutdown,
+                 nsIObserver* aIdleObserver = nullptr);
+
+  /**
+   * Add an observer that will be notified when the thread is idle and about to
+   * be shut down. The aSubject argument can be QueryInterface'd to an nsIThread
+   * that can be used to post cleanup events. The aTopic argument will be
+   * IDLE_THREAD_TOPIC, and aData will be null. The LazyIdleThread does not add
+   * a reference to the observer to avoid circular references as it is assumed
+   * to be the owner. It is the caller's responsibility to clear this observer
+   * if the pointer becomes invalid.
+   */
+  void SetWeakIdleObserver(nsIObserver* aObserver);
+
+  /**
+   * Disable the idle timeout for this thread. No effect if the timeout is
+   * already disabled.
+   */
+  void DisableIdleTimeout();
+
+  /**
+   * Enable the idle timeout. No effect if the timeout is already enabled.
+   */
+  void EnableIdleTimeout();
+
+private:
+  /**
+   * Calls Shutdown().
+   */
+  ~LazyIdleThread();
+
+  /**
+   * Called just before dispatching to mThread.
+   */
+  void PreDispatch();
+
+  /**
+   * Makes sure a valid thread lives in mThread.
+   */
+  nsresult EnsureThread();
+
+  /**
+   * Called on mThread to set up the thread observer.
+   */
+  void InitThread();
+
+  /**
+   * Called on mThread to clean up the thread observer.
+   */
+  void CleanupThread();
+
+  /**
+   * Called on the main thread when mThread believes itself to be idle. Sets up
+   * the idle timer.
+   */
+  void ScheduleTimer();
+
+  /**
+   * Called when we are shutting down mThread.
+   */
+  nsresult ShutdownThread();
+
+  /**
+   * Deletes this object. Used to delay calling mThread->Shutdown() during the
+   * final release (during a GC, for instance).
+   */
+  void SelfDestruct();
+
+  /**
+   * Returns true if events should be queued rather than immediately dispatched
+   * to mThread. Currently only happens when the thread is shutting down.
+   */
+  bool UseRunnableQueue()
+  {
+    return !!mQueuedRunnables;
+  }
+
+  /**
+   * Protects data that is accessed on both threads.
+   */
+  mozilla::Mutex mMutex;
+
+  /**
+   * Touched on both threads but set before mThread is created. Used to direct
+   * timer events to the owning thread.
+   */
+  nsCOMPtr<nsIThread> mOwningThread;
+
+  /**
+   * Only accessed on the owning thread. Set by EnsureThread().
+   */
+  nsCOMPtr<nsIThread> mThread;
+
+  /**
+   * Protected by mMutex. Created when mThread has no pending events and fired
+   * at mOwningThread. Any thread that dispatches to mThread will take ownership
+   * of the timer and fire a separate cancel event to the owning thread.
+   */
+  nsCOMPtr<nsITimer> mIdleTimer;
+
+  /**
+   * Idle observer. Called when the thread is about to be shut down. Released
+   * only when Shutdown() is called.
+   */
+  nsIObserver* MOZ_UNSAFE_REF("See the documentation for SetWeakIdleObserver for "
+                              "how the owner of LazyIdleThread should manage the "
+                              "lifetime information of this field") mIdleObserver;
+
+  /**
+   * Temporary storage for events that happen to be dispatched while we're in
+   * the process of shutting down our real thread.
+   */
+  nsTArray<nsCOMPtr<nsIRunnable>>* mQueuedRunnables;
+
+  /**
+   * The number of milliseconds a thread should be idle before dying.
+   */
+  const uint32_t mIdleTimeoutMS;
+
+  /**
+   * The number of events that are pending on mThread. A nonzero value means
+   * that the thread cannot be cleaned up.
+   */
+  uint32_t mPendingEventCount;
+
+  /**
+   * The number of times that mThread has dispatched an idle notification. Any
+   * timer that fires while this count is nonzero can safely be ignored as
+   * another timer will be on the way.
+   */
+  uint32_t mIdleNotificationCount;
+
+  /**
+   * Whether or not the thread should automatically shutdown. If the owner
+   * specified ManualShutdown at construction time then the owner should take
+   * care to call Shutdown() manually when appropriate.
+   */
+  ShutdownMethod mShutdownMethod;
+
+  /**
+   * Only accessed on the owning thread. Set to true when Shutdown() has been
+   * called and prevents EnsureThread() from recreating mThread.
+   */
+  bool mShutdown;
+
+  /**
+   * Set from CleanupThread and lasting until the thread has shut down. Prevents
+   * further idle notifications during the shutdown process.
+   */
+  bool mThreadIsShuttingDown;
+
+  /**
+   * Whether or not the idle timeout is enabled.
+   */
+  bool mIdleTimeoutEnabled;
+
+  /**
+   * Name of the thread, set on the actual thread after it gets created.
+   */
+  nsCString mName;
+};
+
+} // namespace mozilla
+
+#endif // mozilla_lazyidlethread_h__
diff --git a/xpcom/threads/LeakRefPtr.h b/xpcom/threads/LeakRefPtr.h
new file mode 100644
index 000000000..56f5d90af
--- /dev/null
+++ b/xpcom/threads/LeakRefPtr.h
@@ -0,0 +1,52 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Smart pointer which leaks its owning refcounted object by default. */
+
+#ifndef LeakRefPtr_h
+#define LeakRefPtr_h
+
+#include "mozilla/AlreadyAddRefed.h"
+
+namespace mozilla {
+
+/**
+ * Instance of this class behaves like a raw pointer which leaks the
+ * resource it's owning if not explicitly released.
+ */
+template<class T>
+class LeakRefPtr
+{
+public:
+  explicit LeakRefPtr(already_AddRefed<T>&& aPtr)
+    : mRawPtr(aPtr.take()) { }
+
+  explicit operator bool() const { return !!mRawPtr; }
+
+  LeakRefPtr<T>& operator=(already_AddRefed<T>&& aPtr)
+  {
+    mRawPtr = aPtr.take();
+    return *this;
+  }
+
+  T* get() const { return mRawPtr; }
+
+  already_AddRefed<T> take()
+  {
+    T* rawPtr = mRawPtr;
+    mRawPtr = nullptr;
+    return already_AddRefed<T>(rawPtr);
+  }
+
+  void release() { NS_RELEASE(mRawPtr); }
+
+private:
+  T* MOZ_OWNING_REF mRawPtr;
+};
+
+} // namespace mozilla
+
+#endif // LeakRefPtr_h
diff --git a/xpcom/threads/MainThreadIdlePeriod.cpp b/xpcom/threads/MainThreadIdlePeriod.cpp
new file mode 100644
index 000000000..4a5f99dd7
--- /dev/null
+++ b/xpcom/threads/MainThreadIdlePeriod.cpp
@@ -0,0 +1,76 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "MainThreadIdlePeriod.h"
+
+#include "mozilla/Maybe.h"
+#include "mozilla/Preferences.h"
+#include "nsRefreshDriver.h"
+
+#define DEFAULT_LONG_IDLE_PERIOD 50.0f
+#define DEFAULT_MIN_IDLE_PERIOD 3.0f
+
+namespace mozilla {
+
+NS_IMETHODIMP
+MainThreadIdlePeriod::GetIdlePeriodHint(TimeStamp* aIdleDeadline)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aIdleDeadline);
+
+  Maybe<TimeStamp> deadline = nsRefreshDriver::GetIdleDeadlineHint();
+
+  if (deadline.isSome()) {
+    // If the idle period is too small, then just return a null time
+    // to indicate we are busy. Otherwise return the actual deadline.
+    TimeDuration minIdlePeriod =
+      TimeDuration::FromMilliseconds(GetMinIdlePeriod());
+    bool busySoon = deadline.value().IsNull() ||
+                    (TimeStamp::Now() >= (deadline.value() - minIdlePeriod));
+    *aIdleDeadline = busySoon ? TimeStamp() : deadline.value();
+  } else {
+    *aIdleDeadline =
+      TimeStamp::Now() + TimeDuration::FromMilliseconds(GetLongIdlePeriod());
+  }
+
+  return NS_OK;
+}
+
+/* static */ float
+MainThreadIdlePeriod::GetLongIdlePeriod()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  static float sLongIdlePeriod = DEFAULT_LONG_IDLE_PERIOD;
+  static bool sInitialized = false;
+
+  if (!sInitialized && Preferences::IsServiceAvailable()) {
+    sInitialized = true;
+    Preferences::AddFloatVarCache(&sLongIdlePeriod, "idle_queue.long_period",
+                                  DEFAULT_LONG_IDLE_PERIOD);
+  }
+
+  return sLongIdlePeriod;
+}
+
+/* static */ float
+MainThreadIdlePeriod::GetMinIdlePeriod()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  static float sMinIdlePeriod = DEFAULT_MIN_IDLE_PERIOD;
+  static bool sInitialized = false;
+
+  if (!sInitialized && Preferences::IsServiceAvailable()) {
+    sInitialized = true;
+    Preferences::AddFloatVarCache(&sMinIdlePeriod, "idle_queue.min_period",
+                                  DEFAULT_MIN_IDLE_PERIOD);
+  }
+
+  return sMinIdlePeriod;
+}
+
+} // namespace mozilla
diff --git a/xpcom/threads/MainThreadIdlePeriod.h b/xpcom/threads/MainThreadIdlePeriod.h
new file mode 100644
index 000000000..2b773551c
--- /dev/null
+++ b/xpcom/threads/MainThreadIdlePeriod.h
@@ -0,0 +1,28 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_mainthreadidleperiod_h
+#define mozilla_dom_mainthreadidleperiod_h
+
+#include "mozilla/TimeStamp.h"
+#include "nsThreadUtils.h"
+
+namespace mozilla {
+
+class MainThreadIdlePeriod final : public IdlePeriod
+{
+public:
+  NS_DECL_NSIIDLEPERIOD
+
+  static float GetLongIdlePeriod();
+  static float GetMinIdlePeriod();
+private:
+  virtual ~MainThreadIdlePeriod() {}
+};
+
+} // namespace mozilla
+
+#endif // mozilla_dom_mainthreadidleperiod_h
diff --git a/xpcom/threads/MozPromise.h b/xpcom/threads/MozPromise.h
new file mode 100644
index 000000000..7a2921d2a
--- /dev/null
+++ b/xpcom/threads/MozPromise.h
@@ -0,0 +1,1067 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#if !defined(MozPromise_h_)
+#define MozPromise_h_
+
+#include "mozilla/AbstractThread.h"
+#include "mozilla/IndexSequence.h"
+#include "mozilla/Logging.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/Monitor.h"
+#include "mozilla/Tuple.h"
+#include "mozilla/TypeTraits.h"
+
+#include "nsTArray.h"
+#include "nsThreadUtils.h"
+
+#if defined(DEBUG) || !defined(RELEASE_OR_BETA)
+#define PROMISE_DEBUG
+#endif
+
+#ifdef PROMISE_DEBUG
+#define PROMISE_ASSERT MOZ_RELEASE_ASSERT
+#else
+#define PROMISE_ASSERT(...) do { } while (0)
+#endif
+
+namespace mozilla {
+
+extern LazyLogModule gMozPromiseLog;
+
+#define PROMISE_LOG(x, ...) \
+  MOZ_LOG(gMozPromiseLog, mozilla::LogLevel::Debug, (x, ##__VA_ARGS__))
+
+namespace detail {
+template<typename ThisType, typename Ret, typename ArgType>
+static TrueType TakesArgumentHelper(Ret (ThisType::*)(ArgType));
+template<typename ThisType, typename Ret, typename ArgType>
+static TrueType TakesArgumentHelper(Ret (ThisType::*)(ArgType) const);
+template<typename ThisType, typename Ret>
+static FalseType TakesArgumentHelper(Ret (ThisType::*)());
+template<typename ThisType, typename Ret>
+static FalseType TakesArgumentHelper(Ret (ThisType::*)() const);
+
+template<typename ThisType, typename Ret, typename ArgType>
+static Ret ReturnTypeHelper(Ret (ThisType::*)(ArgType));
+template<typename ThisType, typename Ret, typename ArgType>
+static Ret ReturnTypeHelper(Ret (ThisType::*)(ArgType) const);
+template<typename ThisType, typename Ret>
+static Ret ReturnTypeHelper(Ret (ThisType::*)());
+template<typename ThisType, typename Ret>
+static Ret ReturnTypeHelper(Ret (ThisType::*)() const);
+
+template<typename MethodType>
+struct ReturnType {
+  typedef decltype(detail::ReturnTypeHelper(DeclVal<MethodType>())) Type;
+};
+
+} // namespace detail
+
+template<typename MethodType>
+struct TakesArgument {
+  static const bool value = decltype(detail::TakesArgumentHelper(DeclVal<MethodType>()))::value;
+};
+
+template<typename MethodType, typename TargetType>
+struct ReturnTypeIs {
+  static const bool value = IsConvertible<typename detail::ReturnType<MethodType>::Type, TargetType>::value;
+};
+
+/*
+ * A promise manages an asynchronous request that may or may not be able to be
+ * fulfilled immediately. When an API returns a promise, the consumer may attach
+ * callbacks to be invoked (asynchronously, on a specified thread) when the
+ * request is either completed (resolved) or cannot be completed (rejected).
+ * Whereas JS promise callbacks are dispatched from Microtask checkpoints,
+ * MozPromises resolution/rejection make a normal round-trip through the event
+ * loop, which simplifies their ordering semantics relative to other native code.
+ *
+ * MozPromises attempt to mirror the spirit of JS Promises to the extent that
+ * is possible (and desirable) in C++. While the intent is that MozPromises
+ * feel familiar to programmers who are accustomed to their JS-implemented cousin,
+ * we don't shy away from imposing restrictions and adding features that make
+ * sense for the use cases we encounter.
+ *
+ * A MozPromise is ThreadSafe, and may be ->Then()ed on any thread. The Then()
+ * call accepts resolve and reject callbacks, and returns a MozPromise::Request.
+ * The Request object serves several purposes for the consumer.
+ *
+ *   (1) It allows the caller to cancel the delivery of the resolve/reject value
+ *       if it has not already occurred, via Disconnect() (this must be done on
+ *       the target thread to avoid racing).
+ *
+ *   (2) It provides access to a "Completion Promise", which is roughly analagous
+ *       to the Promise returned directly by ->then() calls on JS promises. If
+ *       the resolve/reject callback returns a new MozPromise, that promise is
+ *       chained to the completion promise, such that its resolve/reject value
+ *       will be forwarded along when it arrives. If the resolve/reject callback
+ *       returns void, the completion promise is resolved/rejected with the same
+ *       value that was passed to the callback.
+ *
+ * The MozPromise APIs skirt traditional XPCOM convention by returning nsRefPtrs
+ * (rather than already_AddRefed) from various methods. This is done to allow elegant
+ * chaining of calls without cluttering up the code with intermediate variables, and
+ * without introducing separate API variants for callers that want a return value
+ * (from, say, ->Then()) from those that don't.
+ *
+ * When IsExclusive is true, the MozPromise does a release-mode assertion that
+ * there is at most one call to either Then(...) or ChainTo(...).
+ */
+
+class MozPromiseRefcountable
+{
+public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(MozPromiseRefcountable)
+protected:
+  virtual ~MozPromiseRefcountable() {}
+};
+
+template<typename T> class MozPromiseHolder;
+template<typename ResolveValueT, typename RejectValueT, bool IsExclusive>
+class MozPromise : public MozPromiseRefcountable
+{
+  static const uint32_t sMagic = 0xcecace11;
+
+public:
+  typedef ResolveValueT ResolveValueType;
+  typedef RejectValueT RejectValueType;
+  class ResolveOrRejectValue
+  {
+  public:
+    template<typename ResolveValueType_>
+    void SetResolve(ResolveValueType_&& aResolveValue)
+    {
+      MOZ_ASSERT(IsNothing());
+      mResolveValue.emplace(Forward<ResolveValueType_>(aResolveValue));
+    }
+
+    template<typename RejectValueType_>
+    void SetReject(RejectValueType_&& aRejectValue)
+    {
+      MOZ_ASSERT(IsNothing());
+      mRejectValue.emplace(Forward<RejectValueType_>(aRejectValue));
+    }
+
+    template<typename ResolveValueType_>
+    static ResolveOrRejectValue MakeResolve(ResolveValueType_&& aResolveValue)
+    {
+      ResolveOrRejectValue val;
+      val.SetResolve(Forward<ResolveValueType_>(aResolveValue));
+      return val;
+    }
+
+    template<typename RejectValueType_>
+    static ResolveOrRejectValue MakeReject(RejectValueType_&& aRejectValue)
+    {
+      ResolveOrRejectValue val;
+      val.SetReject(Forward<RejectValueType_>(aRejectValue));
+      return val;
+    }
+
+    bool IsResolve() const { return mResolveValue.isSome(); }
+    bool IsReject() const { return mRejectValue.isSome(); }
+    bool IsNothing() const { return mResolveValue.isNothing() && mRejectValue.isNothing(); }
+
+    const ResolveValueType& ResolveValue() const { return mResolveValue.ref(); }
+    const RejectValueType& RejectValue() const { return mRejectValue.ref(); }
+
+  private:
+    Maybe<ResolveValueType> mResolveValue;
+    Maybe<RejectValueType> mRejectValue;
+  };
+
+protected:
+  // MozPromise is the public type, and never constructed directly. Construct
+  // a MozPromise::Private, defined below.
+  MozPromise(const char* aCreationSite, bool aIsCompletionPromise)
+    : mCreationSite(aCreationSite)
+    , mMutex("MozPromise Mutex")
+    , mHaveRequest(false)
+    , mIsCompletionPromise(aIsCompletionPromise)
+#ifdef PROMISE_DEBUG
+    , mMagic4(mMutex.mLock)
+#endif
+  {
+    PROMISE_LOG("%s creating MozPromise (%p)", mCreationSite, this);
+  }
+
+public:
+  // MozPromise::Private allows us to separate the public interface (upon which
+  // consumers of the promise may invoke methods like Then()) from the private
+  // interface (upon which the creator of the promise may invoke Resolve() or
+  // Reject()). APIs should create and store a MozPromise::Private (usually
+  // via a MozPromiseHolder), and return a MozPromise to consumers.
+  //
+  // NB: We can include the definition of this class inline once B2G ICS is gone.
+  class Private;
+
+  template<typename ResolveValueType_>
+  static RefPtr<MozPromise>
+  CreateAndResolve(ResolveValueType_&& aResolveValue, const char* aResolveSite)
+  {
+    RefPtr<typename MozPromise::Private> p = new MozPromise::Private(aResolveSite);
+    p->Resolve(Forward<ResolveValueType_>(aResolveValue), aResolveSite);
+    return p.forget();
+  }
+
+  template<typename RejectValueType_>
+  static RefPtr<MozPromise>
+  CreateAndReject(RejectValueType_&& aRejectValue, const char* aRejectSite)
+  {
+    RefPtr<typename MozPromise::Private> p = new MozPromise::Private(aRejectSite);
+    p->Reject(Forward<RejectValueType_>(aRejectValue), aRejectSite);
+    return p.forget();
+  }
+
+  typedef MozPromise<nsTArray<ResolveValueType>, RejectValueType, IsExclusive> AllPromiseType;
+private:
+  class AllPromiseHolder : public MozPromiseRefcountable
+  {
+  public:
+    explicit AllPromiseHolder(size_t aDependentPromises)
+      : mPromise(new typename AllPromiseType::Private(__func__))
+      , mOutstandingPromises(aDependentPromises)
+    {
+      mResolveValues.SetLength(aDependentPromises);
+    }
+
+    void Resolve(size_t aIndex, const ResolveValueType& aResolveValue)
+    {
+      if (!mPromise) {
+        // Already rejected.
+        return;
+      }
+
+      mResolveValues[aIndex].emplace(aResolveValue);
+      if (--mOutstandingPromises == 0) {
+        nsTArray<ResolveValueType> resolveValues;
+        resolveValues.SetCapacity(mResolveValues.Length());
+        for (size_t i = 0; i < mResolveValues.Length(); ++i) {
+          resolveValues.AppendElement(mResolveValues[i].ref());
+        }
+
+        mPromise->Resolve(resolveValues, __func__);
+        mPromise = nullptr;
+        mResolveValues.Clear();
+      }
+    }
+
+    void Reject(const RejectValueType& aRejectValue)
+    {
+      if (!mPromise) {
+        // Already rejected.
+        return;
+      }
+
+      mPromise->Reject(aRejectValue, __func__);
+      mPromise = nullptr;
+      mResolveValues.Clear();
+    }
+
+    AllPromiseType* Promise() { return mPromise; }
+
+  private:
+    nsTArray<Maybe<ResolveValueType>> mResolveValues;
+    RefPtr<typename AllPromiseType::Private> mPromise;
+    size_t mOutstandingPromises;
+  };
+public:
+
+  static RefPtr<AllPromiseType> All(AbstractThread* aProcessingThread, nsTArray<RefPtr<MozPromise>>& aPromises)
+  {
+    RefPtr<AllPromiseHolder> holder = new AllPromiseHolder(aPromises.Length());
+    for (size_t i = 0; i < aPromises.Length(); ++i) {
+      aPromises[i]->Then(aProcessingThread, __func__,
+        [holder, i] (ResolveValueType aResolveValue) -> void { holder->Resolve(i, aResolveValue); },
+        [holder] (RejectValueType aRejectValue) -> void { holder->Reject(aRejectValue); }
+      );
+    }
+    return holder->Promise();
+  }
+
+  class Request : public MozPromiseRefcountable
+  {
+  public:
+    virtual void Disconnect() = 0;
+
+    virtual MozPromise* CompletionPromise() = 0;
+
+    virtual void AssertIsDead() = 0;
+
+  protected:
+    Request() : mComplete(false), mDisconnected(false) {}
+    virtual ~Request() {}
+
+    bool mComplete;
+    bool mDisconnected;
+  };
+
+protected:
+
+  /*
+   * A ThenValue tracks a single consumer waiting on the promise. When a consumer
+   * invokes promise->Then(...), a ThenValue is created. Once the Promise is
+   * resolved or rejected, a {Resolve,Reject}Runnable is dispatched, which
+   * invokes the resolve/reject method and then deletes the ThenValue.
+   */
+  class ThenValueBase : public Request
+  {
+    static const uint32_t sMagic = 0xfadece11;
+
+  public:
+    class ResolveOrRejectRunnable : public Runnable
+    {
+    public:
+      ResolveOrRejectRunnable(ThenValueBase* aThenValue, MozPromise* aPromise)
+        : mThenValue(aThenValue)
+        , mPromise(aPromise)
+      {
+        MOZ_DIAGNOSTIC_ASSERT(!mPromise->IsPending());
+      }
+
+      ~ResolveOrRejectRunnable()
+      {
+        if (mThenValue) {
+          mThenValue->AssertIsDead();
+        }
+      }
+
+      NS_IMETHOD Run() override
+      {
+        PROMISE_LOG("ResolveOrRejectRunnable::Run() [this=%p]", this);
+        mThenValue->DoResolveOrReject(mPromise->Value());
+        mThenValue = nullptr;
+        mPromise = nullptr;
+        return NS_OK;
+      }
+
+    private:
+      RefPtr<ThenValueBase> mThenValue;
+      RefPtr<MozPromise> mPromise;
+    };
+
+    explicit ThenValueBase(AbstractThread* aResponseTarget, const char* aCallSite)
+      : mResponseTarget(aResponseTarget), mCallSite(aCallSite) {}
+
+#ifdef PROMISE_DEBUG
+    ~ThenValueBase()
+    {
+      mMagic1 = 0;
+      mMagic2 = 0;
+    }
+#endif
+
+    MozPromise* CompletionPromise() override
+    {
+      MOZ_DIAGNOSTIC_ASSERT(mResponseTarget->IsCurrentThreadIn());
+      MOZ_DIAGNOSTIC_ASSERT(!Request::mComplete);
+      if (!mCompletionPromise) {
+        mCompletionPromise = new MozPromise::Private(
+          "<completion promise>", true /* aIsCompletionPromise */);
+      }
+      return mCompletionPromise;
+    }
+
+    void AssertIsDead() override
+    {
+      PROMISE_ASSERT(mMagic1 == sMagic && mMagic2 == sMagic);
+      // We want to assert that this ThenValues is dead - that is to say, that
+      // there are no consumers waiting for the result. In the case of a normal
+      // ThenValue, we check that it has been disconnected, which is the way
+      // that the consumer signals that it no longer wishes to hear about the
+      // result. If this ThenValue has a completion promise (which is mutually
+      // exclusive with being disconnectable), we recursively assert that every
+      // ThenValue associated with the completion promise is dead.
+      if (mCompletionPromise) {
+        mCompletionPromise->AssertIsDead();
+      } else {
+        MOZ_DIAGNOSTIC_ASSERT(Request::mDisconnected);
+      }
+    }
+
+    void Dispatch(MozPromise *aPromise)
+    {
+      PROMISE_ASSERT(mMagic1 == sMagic && mMagic2 == sMagic);
+      aPromise->mMutex.AssertCurrentThreadOwns();
+      MOZ_ASSERT(!aPromise->IsPending());
+
+      RefPtr<Runnable> runnable =
+        static_cast<Runnable*>(new (typename ThenValueBase::ResolveOrRejectRunnable)(this, aPromise));
+      PROMISE_LOG("%s Then() call made from %s [Runnable=%p, Promise=%p, ThenValue=%p]",
+                  aPromise->mValue.IsResolve() ? "Resolving" : "Rejecting", ThenValueBase::mCallSite,
+                  runnable.get(), aPromise, this);
+
+      // Promise consumers are allowed to disconnect the Request object and
+      // then shut down the thread or task queue that the promise result would
+      // be dispatched on. So we unfortunately can't assert that promise
+      // dispatch succeeds. :-(
+      mResponseTarget->Dispatch(runnable.forget(), AbstractThread::DontAssertDispatchSuccess);
+    }
+
+    virtual void Disconnect() override
+    {
+      MOZ_DIAGNOSTIC_ASSERT(ThenValueBase::mResponseTarget->IsCurrentThreadIn());
+      MOZ_DIAGNOSTIC_ASSERT(!Request::mComplete);
+      Request::mDisconnected = true;
+
+      // We could support rejecting the completion promise on disconnection, but
+      // then we'd need to have some sort of default reject value. The use cases
+      // of disconnection and completion promise chaining seem pretty orthogonal,
+      // so let's use assert against it.
+      MOZ_DIAGNOSTIC_ASSERT(!mCompletionPromise);
+    }
+
+  protected:
+    virtual already_AddRefed<MozPromise> DoResolveOrRejectInternal(const ResolveOrRejectValue& aValue) = 0;
+
+    void DoResolveOrReject(const ResolveOrRejectValue& aValue)
+    {
+      PROMISE_ASSERT(mMagic1 == sMagic && mMagic2 == sMagic);
+      MOZ_DIAGNOSTIC_ASSERT(mResponseTarget->IsCurrentThreadIn());
+      Request::mComplete = true;
+      if (Request::mDisconnected) {
+        PROMISE_LOG("ThenValue::DoResolveOrReject disconnected - bailing out [this=%p]", this);
+        return;
+      }
+
+      // Invoke the resolve or reject method.
+      RefPtr<MozPromise> p = DoResolveOrRejectInternal(aValue);
+
+      // If there's a completion promise, resolve it appropriately with the
+      // result of the method.
+      //
+      // We jump through some hoops to cast to MozPromise::Private here. This
+      // can go away when we can just declare mCompletionPromise as
+      // MozPromise::Private. See the declaration below.
+      RefPtr<MozPromise::Private> completionPromise =
+        dont_AddRef(static_cast<MozPromise::Private*>(mCompletionPromise.forget().take()));
+      if (completionPromise) {
+        if (p) {
+          p->ChainTo(completionPromise.forget(), "<chained completion promise>");
+        } else {
+          completionPromise->ResolveOrReject(aValue, "<completion of non-promise-returning method>");
+        }
+      }
+    }
+
+    RefPtr<AbstractThread> mResponseTarget; // May be released on any thread.
+#ifdef PROMISE_DEBUG
+    uint32_t mMagic1 = sMagic;
+#endif
+    // Declaring RefPtr<MozPromise::Private> here causes build failures
+    // on MSVC because MozPromise::Private is only forward-declared at this
+    // point. This hack can go away when we inline-declare MozPromise::Private,
+    // which is blocked on the B2G ICS compiler being too old.
+    RefPtr<MozPromise> mCompletionPromise;
+#ifdef PROMISE_DEBUG
+    uint32_t mMagic2 = sMagic;
+#endif
+    const char* mCallSite;
+  };
+
+  /*
+   * We create two overloads for invoking Resolve/Reject Methods so as to
+   * make the resolve/reject value argument "optional".
+   */
+
+  template<typename ThisType, typename MethodType, typename ValueType>
+  static typename EnableIf<ReturnTypeIs<MethodType, RefPtr<MozPromise>>::value &&
+                           TakesArgument<MethodType>::value,
+                           already_AddRefed<MozPromise>>::Type
+  InvokeCallbackMethod(ThisType* aThisVal, MethodType aMethod, ValueType&& aValue)
+  {
+    return ((*aThisVal).*aMethod)(Forward<ValueType>(aValue)).forget();
+  }
+
+  template<typename ThisType, typename MethodType, typename ValueType>
+  static typename EnableIf<ReturnTypeIs<MethodType, void>::value &&
+                           TakesArgument<MethodType>::value,
+                           already_AddRefed<MozPromise>>::Type
+  InvokeCallbackMethod(ThisType* aThisVal, MethodType aMethod, ValueType&& aValue)
+  {
+    ((*aThisVal).*aMethod)(Forward<ValueType>(aValue));
+    return nullptr;
+  }
+
+  template<typename ThisType, typename MethodType, typename ValueType>
+  static typename EnableIf<ReturnTypeIs<MethodType, RefPtr<MozPromise>>::value &&
+                           !TakesArgument<MethodType>::value,
+                           already_AddRefed<MozPromise>>::Type
+  InvokeCallbackMethod(ThisType* aThisVal, MethodType aMethod, ValueType&& aValue)
+  {
+    return ((*aThisVal).*aMethod)().forget();
+  }
+
+  template<typename ThisType, typename MethodType, typename ValueType>
+  static typename EnableIf<ReturnTypeIs<MethodType, void>::value &&
+                           !TakesArgument<MethodType>::value,
+                           already_AddRefed<MozPromise>>::Type
+  InvokeCallbackMethod(ThisType* aThisVal, MethodType aMethod, ValueType&& aValue)
+  {
+    ((*aThisVal).*aMethod)();
+    return nullptr;
+  }
+
+  template<typename ThisType, typename ResolveMethodType, typename RejectMethodType>
+  class MethodThenValue : public ThenValueBase
+  {
+  public:
+    MethodThenValue(AbstractThread* aResponseTarget, ThisType* aThisVal,
+                    ResolveMethodType aResolveMethod, RejectMethodType aRejectMethod,
+                    const char* aCallSite)
+      : ThenValueBase(aResponseTarget, aCallSite)
+      , mThisVal(aThisVal)
+      , mResolveMethod(aResolveMethod)
+      , mRejectMethod(aRejectMethod) {}
+
+  virtual void Disconnect() override
+  {
+    ThenValueBase::Disconnect();
+
+    // If a Request has been disconnected, we don't guarantee that the
+    // resolve/reject runnable will be dispatched. Null out our refcounted
+    // this-value now so that it's released predictably on the dispatch thread.
+    mThisVal = nullptr;
+  }
+
+  protected:
+    virtual already_AddRefed<MozPromise> DoResolveOrRejectInternal(const ResolveOrRejectValue& aValue) override
+    {
+      RefPtr<MozPromise> completion;
+      if (aValue.IsResolve()) {
+        completion = InvokeCallbackMethod(mThisVal.get(), mResolveMethod, aValue.ResolveValue());
+      } else {
+        completion = InvokeCallbackMethod(mThisVal.get(), mRejectMethod, aValue.RejectValue());
+      }
+
+      // Null out mThisVal after invoking the callback so that any references are
+      // released predictably on the dispatch thread. Otherwise, it would be
+      // released on whatever thread last drops its reference to the ThenValue,
+      // which may or may not be ok.
+      mThisVal = nullptr;
+
+      return completion.forget();
+    }
+
+  private:
+    RefPtr<ThisType> mThisVal; // Only accessed and refcounted on dispatch thread.
+    ResolveMethodType mResolveMethod;
+    RejectMethodType mRejectMethod;
+  };
+
+  // NB: We could use std::function here instead of a template if it were supported. :-(
+  template<typename ResolveFunction, typename RejectFunction>
+  class FunctionThenValue : public ThenValueBase
+  {
+  public:
+    FunctionThenValue(AbstractThread* aResponseTarget,
+                      ResolveFunction&& aResolveFunction,
+                      RejectFunction&& aRejectFunction,
+                      const char* aCallSite)
+      : ThenValueBase(aResponseTarget, aCallSite)
+    {
+      mResolveFunction.emplace(Move(aResolveFunction));
+      mRejectFunction.emplace(Move(aRejectFunction));
+    }
+
+  virtual void Disconnect() override
+  {
+    ThenValueBase::Disconnect();
+
+    // If a Request has been disconnected, we don't guarantee that the
+    // resolve/reject runnable will be dispatched. Destroy our callbacks
+    // now so that any references in closures are released predictable on
+    // the dispatch thread.
+    mResolveFunction.reset();
+    mRejectFunction.reset();
+  }
+
+  protected:
+    virtual already_AddRefed<MozPromise> DoResolveOrRejectInternal(const ResolveOrRejectValue& aValue) override
+    {
+      // Note: The usage of InvokeCallbackMethod here requires that
+      // ResolveFunction/RejectFunction are capture-lambdas (i.e. anonymous
+      // classes with ::operator()), since it allows us to share code more easily.
+      // We could fix this if need be, though it's quite easy to work around by
+      // just capturing something.
+      RefPtr<MozPromise> completion;
+      if (aValue.IsResolve()) {
+        completion = InvokeCallbackMethod(mResolveFunction.ptr(), &ResolveFunction::operator(), aValue.ResolveValue());
+      } else {
+        completion = InvokeCallbackMethod(mRejectFunction.ptr(), &RejectFunction::operator(), aValue.RejectValue());
+      }
+
+      // Destroy callbacks after invocation so that any references in closures are
+      // released predictably on the dispatch thread. Otherwise, they would be
+      // released on whatever thread last drops its reference to the ThenValue,
+      // which may or may not be ok.
+      mResolveFunction.reset();
+      mRejectFunction.reset();
+
+      return completion.forget();
+    }
+
+  private:
+    Maybe<ResolveFunction> mResolveFunction; // Only accessed and deleted on dispatch thread.
+    Maybe<RejectFunction> mRejectFunction; // Only accessed and deleted on dispatch thread.
+  };
+
+public:
+  void ThenInternal(AbstractThread* aResponseThread, ThenValueBase* aThenValue,
+                    const char* aCallSite)
+  {
+    PROMISE_ASSERT(mMagic1 == sMagic && mMagic2 == sMagic && mMagic3 == sMagic && mMagic4 == mMutex.mLock);
+    MutexAutoLock lock(mMutex);
+    MOZ_ASSERT(aResponseThread->IsDispatchReliable());
+    MOZ_DIAGNOSTIC_ASSERT(!IsExclusive || !mHaveRequest);
+    mHaveRequest = true;
+    PROMISE_LOG("%s invoking Then() [this=%p, aThenValue=%p, isPending=%d]",
+                aCallSite, this, aThenValue, (int) IsPending());
+    if (!IsPending()) {
+      aThenValue->Dispatch(this);
+    } else {
+      mThenValues.AppendElement(aThenValue);
+    }
+  }
+
+public:
+
+  template<typename ThisType, typename ResolveMethodType, typename RejectMethodType>
+  RefPtr<Request> Then(AbstractThread* aResponseThread, const char* aCallSite, ThisType* aThisVal,
+                         ResolveMethodType aResolveMethod, RejectMethodType aRejectMethod)
+  {
+    RefPtr<ThenValueBase> thenValue = new MethodThenValue<ThisType, ResolveMethodType, RejectMethodType>(
+                                              aResponseThread, aThisVal, aResolveMethod, aRejectMethod, aCallSite);
+    ThenInternal(aResponseThread, thenValue, aCallSite);
+    return thenValue.forget(); // Implicit conversion from already_AddRefed<ThenValueBase> to RefPtr<Request>.
+  }
+
+  template<typename ResolveFunction, typename RejectFunction>
+  RefPtr<Request> Then(AbstractThread* aResponseThread, const char* aCallSite,
+                         ResolveFunction&& aResolveFunction, RejectFunction&& aRejectFunction)
+  {
+    RefPtr<ThenValueBase> thenValue = new FunctionThenValue<ResolveFunction, RejectFunction>(aResponseThread,
+                                              Move(aResolveFunction), Move(aRejectFunction), aCallSite);
+    ThenInternal(aResponseThread, thenValue, aCallSite);
+    return thenValue.forget(); // Implicit conversion from already_AddRefed<ThenValueBase> to RefPtr<Request>.
+  }
+
+  void ChainTo(already_AddRefed<Private> aChainedPromise, const char* aCallSite)
+  {
+    MutexAutoLock lock(mMutex);
+    MOZ_DIAGNOSTIC_ASSERT(!IsExclusive || !mHaveRequest);
+    mHaveRequest = true;
+    RefPtr<Private> chainedPromise = aChainedPromise;
+    PROMISE_LOG("%s invoking Chain() [this=%p, chainedPromise=%p, isPending=%d]",
+                aCallSite, this, chainedPromise.get(), (int) IsPending());
+    if (!IsPending()) {
+      ForwardTo(chainedPromise);
+    } else {
+      mChainedPromises.AppendElement(chainedPromise);
+    }
+  }
+
+  // Note we expose the function AssertIsDead() instead of IsDead() since
+  // checking IsDead() is a data race in the situation where the request is not
+  // dead. Therefore we enforce the form |Assert(IsDead())| by exposing
+  // AssertIsDead() only.
+  void AssertIsDead()
+  {
+    PROMISE_ASSERT(mMagic1 == sMagic && mMagic2 == sMagic && mMagic3 == sMagic && mMagic4 == mMutex.mLock);
+    MutexAutoLock lock(mMutex);
+    for (auto&& then : mThenValues) {
+      then->AssertIsDead();
+    }
+    for (auto&& chained : mChainedPromises) {
+      chained->AssertIsDead();
+    }
+  }
+
+protected:
+  bool IsPending() const { return mValue.IsNothing(); }
+  const ResolveOrRejectValue& Value() const
+  {
+    // This method should only be called once the value has stabilized. As
+    // such, we don't need to acquire the lock here.
+    MOZ_DIAGNOSTIC_ASSERT(!IsPending());
+    return mValue;
+  }
+
+  void DispatchAll()
+  {
+    mMutex.AssertCurrentThreadOwns();
+    for (size_t i = 0; i < mThenValues.Length(); ++i) {
+      mThenValues[i]->Dispatch(this);
+    }
+    mThenValues.Clear();
+
+    for (size_t i = 0; i < mChainedPromises.Length(); ++i) {
+      ForwardTo(mChainedPromises[i]);
+    }
+    mChainedPromises.Clear();
+  }
+
+  void ForwardTo(Private* aOther)
+  {
+    MOZ_ASSERT(!IsPending());
+    if (mValue.IsResolve()) {
+      aOther->Resolve(mValue.ResolveValue(), "<chained promise>");
+    } else {
+      aOther->Reject(mValue.RejectValue(), "<chained promise>");
+    }
+  }
+
+  virtual ~MozPromise()
+  {
+    PROMISE_LOG("MozPromise::~MozPromise [this=%p]", this);
+    AssertIsDead();
+    // We can't guarantee a completion promise will always be revolved or
+    // rejected since ResolveOrRejectRunnable might not run when dispatch fails.
+    if (!mIsCompletionPromise) {
+      MOZ_ASSERT(!IsPending());
+      MOZ_ASSERT(mThenValues.IsEmpty());
+      MOZ_ASSERT(mChainedPromises.IsEmpty());
+    }
+#ifdef PROMISE_DEBUG
+    mMagic1 = 0;
+    mMagic2 = 0;
+    mMagic3 = 0;
+    mMagic4 = nullptr;
+#endif
+  };
+
+  const char* mCreationSite; // For logging
+  Mutex mMutex;
+  ResolveOrRejectValue mValue;
+#ifdef PROMISE_DEBUG
+  uint32_t mMagic1 = sMagic;
+#endif
+  nsTArray<RefPtr<ThenValueBase>> mThenValues;
+#ifdef PROMISE_DEBUG
+  uint32_t mMagic2 = sMagic;
+#endif
+  nsTArray<RefPtr<Private>> mChainedPromises;
+#ifdef PROMISE_DEBUG
+  uint32_t mMagic3 = sMagic;
+#endif
+  bool mHaveRequest;
+  const bool mIsCompletionPromise;
+#ifdef PROMISE_DEBUG
+  void* mMagic4;
+#endif
+};
+
+template<typename ResolveValueT, typename RejectValueT, bool IsExclusive>
+class MozPromise<ResolveValueT, RejectValueT, IsExclusive>::Private
+  : public MozPromise<ResolveValueT, RejectValueT, IsExclusive>
+{
+public:
+  explicit Private(const char* aCreationSite, bool aIsCompletionPromise = false)
+    : MozPromise(aCreationSite, aIsCompletionPromise) {}
+
+  template<typename ResolveValueT_>
+  void Resolve(ResolveValueT_&& aResolveValue, const char* aResolveSite)
+  {
+    PROMISE_ASSERT(mMagic1 == sMagic && mMagic2 == sMagic && mMagic3 == sMagic && mMagic4 == mMutex.mLock);
+    MutexAutoLock lock(mMutex);
+    MOZ_ASSERT(IsPending());
+    PROMISE_LOG("%s resolving MozPromise (%p created at %s)", aResolveSite, this, mCreationSite);
+    mValue.SetResolve(Forward<ResolveValueT_>(aResolveValue));
+    DispatchAll();
+  }
+
+  template<typename RejectValueT_>
+  void Reject(RejectValueT_&& aRejectValue, const char* aRejectSite)
+  {
+    PROMISE_ASSERT(mMagic1 == sMagic && mMagic2 == sMagic && mMagic3 == sMagic && mMagic4 == mMutex.mLock);
+    MutexAutoLock lock(mMutex);
+    MOZ_ASSERT(IsPending());
+    PROMISE_LOG("%s rejecting MozPromise (%p created at %s)", aRejectSite, this, mCreationSite);
+    mValue.SetReject(Forward<RejectValueT_>(aRejectValue));
+    DispatchAll();
+  }
+
+  template<typename ResolveOrRejectValue_>
+  void ResolveOrReject(ResolveOrRejectValue_&& aValue, const char* aSite)
+  {
+    PROMISE_ASSERT(mMagic1 == sMagic && mMagic2 == sMagic && mMagic3 == sMagic && mMagic4 == mMutex.mLock);
+    MutexAutoLock lock(mMutex);
+    MOZ_ASSERT(IsPending());
+    PROMISE_LOG("%s resolveOrRejecting MozPromise (%p created at %s)", aSite, this, mCreationSite);
+    mValue = Forward<ResolveOrRejectValue_>(aValue);
+    DispatchAll();
+  }
+};
+
+// A generic promise type that does the trick for simple use cases.
+typedef MozPromise<bool, nsresult, /* IsExclusive = */ false> GenericPromise;
+
+/*
+ * Class to encapsulate a promise for a particular role. Use this as the member
+ * variable for a class whose method returns a promise.
+ */
+template<typename PromiseType>
+class MozPromiseHolder
+{
+public:
+  MozPromiseHolder()
+    : mMonitor(nullptr) {}
+
+  // Move semantics.
+  MozPromiseHolder& operator=(MozPromiseHolder&& aOther)
+  {
+    MOZ_ASSERT(!mMonitor && !aOther.mMonitor);
+    MOZ_DIAGNOSTIC_ASSERT(!mPromise);
+    mPromise = aOther.mPromise;
+    aOther.mPromise = nullptr;
+    return *this;
+  }
+
+  ~MozPromiseHolder() { MOZ_ASSERT(!mPromise); }
+
+  already_AddRefed<PromiseType> Ensure(const char* aMethodName) {
+    if (mMonitor) {
+      mMonitor->AssertCurrentThreadOwns();
+    }
+    if (!mPromise) {
+      mPromise = new (typename PromiseType::Private)(aMethodName);
+    }
+    RefPtr<PromiseType> p = mPromise.get();
+    return p.forget();
+  }
+
+  // Provide a Monitor that should always be held when accessing this instance.
+  void SetMonitor(Monitor* aMonitor) { mMonitor = aMonitor; }
+
+  bool IsEmpty() const
+  {
+    if (mMonitor) {
+      mMonitor->AssertCurrentThreadOwns();
+    }
+    return !mPromise;
+  }
+
+  already_AddRefed<typename PromiseType::Private> Steal()
+  {
+    if (mMonitor) {
+      mMonitor->AssertCurrentThreadOwns();
+    }
+
+    RefPtr<typename PromiseType::Private> p = mPromise;
+    mPromise = nullptr;
+    return p.forget();
+  }
+
+  void Resolve(typename PromiseType::ResolveValueType aResolveValue,
+               const char* aMethodName)
+  {
+    if (mMonitor) {
+      mMonitor->AssertCurrentThreadOwns();
+    }
+    MOZ_ASSERT(mPromise);
+    mPromise->Resolve(aResolveValue, aMethodName);
+    mPromise = nullptr;
+  }
+
+
+  void ResolveIfExists(typename PromiseType::ResolveValueType aResolveValue,
+                       const char* aMethodName)
+  {
+    if (!IsEmpty()) {
+      Resolve(aResolveValue, aMethodName);
+    }
+  }
+
+  void Reject(typename PromiseType::RejectValueType aRejectValue,
+              const char* aMethodName)
+  {
+    if (mMonitor) {
+      mMonitor->AssertCurrentThreadOwns();
+    }
+    MOZ_ASSERT(mPromise);
+    mPromise->Reject(aRejectValue, aMethodName);
+    mPromise = nullptr;
+  }
+
+
+  void RejectIfExists(typename PromiseType::RejectValueType aRejectValue,
+                      const char* aMethodName)
+  {
+    if (!IsEmpty()) {
+      Reject(aRejectValue, aMethodName);
+    }
+  }
+
+private:
+  Monitor* mMonitor;
+  RefPtr<typename PromiseType::Private> mPromise;
+};
+
+/*
+ * Class to encapsulate a MozPromise::Request reference. Use this as the member
+ * variable for a class waiting on a MozPromise.
+ */
+template<typename PromiseType>
+class MozPromiseRequestHolder
+{
+public:
+  MozPromiseRequestHolder() {}
+  ~MozPromiseRequestHolder() { MOZ_ASSERT(!mRequest); }
+
+  void Begin(RefPtr<typename PromiseType::Request>&& aRequest)
+  {
+    MOZ_DIAGNOSTIC_ASSERT(!Exists());
+    mRequest = Move(aRequest);
+  }
+
+  void Begin(typename PromiseType::Request* aRequest)
+  {
+    MOZ_DIAGNOSTIC_ASSERT(!Exists());
+    mRequest = aRequest;
+  }
+
+  void Complete()
+  {
+    MOZ_DIAGNOSTIC_ASSERT(Exists());
+    mRequest = nullptr;
+  }
+
+  // Disconnects and forgets an outstanding promise. The resolve/reject methods
+  // will never be called.
+  void Disconnect() {
+    MOZ_ASSERT(Exists());
+    mRequest->Disconnect();
+    mRequest = nullptr;
+  }
+
+  void DisconnectIfExists() {
+    if (Exists()) {
+      Disconnect();
+    }
+  }
+
+  bool Exists() const { return !!mRequest; }
+
+private:
+  RefPtr<typename PromiseType::Request> mRequest;
+};
+
+// Asynchronous Potentially-Cross-Thread Method Calls.
+//
+// This machinery allows callers to schedule a promise-returning method to be
+// invoked asynchronously on a given thread, while at the same time receiving
+// a promise upon which to invoke Then() immediately. InvokeAsync dispatches
+// a task to invoke the method on the proper thread and also chain the resulting
+// promise to the one that the caller received, so that resolve/reject values
+// are forwarded through.
+
+namespace detail {
+
+template<typename ReturnType, typename ThisType, typename... ArgTypes, size_t... Indices>
+ReturnType
+MethodCallInvokeHelper(ReturnType(ThisType::*aMethod)(ArgTypes...), ThisType* aThisVal,
+                       Tuple<ArgTypes...>& aArgs, IndexSequence<Indices...>)
+{
+  return ((*aThisVal).*aMethod)(Get<Indices>(aArgs)...);
+}
+
+// Non-templated base class to allow us to use MOZ_COUNT_{C,D}TOR, which cause
+// assertions when used on templated types.
+class MethodCallBase
+{
+public:
+  MethodCallBase() { MOZ_COUNT_CTOR(MethodCallBase); }
+  virtual ~MethodCallBase() { MOZ_COUNT_DTOR(MethodCallBase); }
+};
+
+template<typename PromiseType, typename ThisType, typename... ArgTypes>
+class MethodCall : public MethodCallBase
+{
+public:
+  typedef RefPtr<PromiseType>(ThisType::*MethodType)(ArgTypes...);
+  MethodCall(MethodType aMethod, ThisType* aThisVal, ArgTypes... aArgs)
+    : mMethod(aMethod)
+    , mThisVal(aThisVal)
+    , mArgs(Forward<ArgTypes>(aArgs)...)
+  {}
+
+  RefPtr<PromiseType> Invoke()
+  {
+    return MethodCallInvokeHelper(mMethod, mThisVal.get(), mArgs, typename IndexSequenceFor<ArgTypes...>::Type());
+  }
+
+private:
+  MethodType mMethod;
+  RefPtr<ThisType> mThisVal;
+  Tuple<ArgTypes...> mArgs;
+};
+
+template<typename PromiseType, typename ThisType, typename ...ArgTypes>
+class ProxyRunnable : public Runnable
+{
+public:
+  ProxyRunnable(typename PromiseType::Private* aProxyPromise, MethodCall<PromiseType, ThisType, ArgTypes...>* aMethodCall)
+    : mProxyPromise(aProxyPromise), mMethodCall(aMethodCall) {}
+
+  NS_IMETHOD Run() override
+  {
+    RefPtr<PromiseType> p = mMethodCall->Invoke();
+    mMethodCall = nullptr;
+    p->ChainTo(mProxyPromise.forget(), "<Proxy Promise>");
+    return NS_OK;
+  }
+
+private:
+  RefPtr<typename PromiseType::Private> mProxyPromise;
+  nsAutoPtr<MethodCall<PromiseType, ThisType, ArgTypes...>> mMethodCall;
+};
+
+constexpr bool Any()
+{
+  return false;
+}
+
+template <typename T1>
+constexpr bool Any(T1 a)
+{
+  return static_cast<bool>(a);
+}
+
+template <typename T1, typename... Ts>
+constexpr bool Any(T1 a, Ts... aOthers)
+{
+  return a || Any(aOthers...);
+}
+
+} // namespace detail
+
+template<typename PromiseType, typename ThisType, typename ...ArgTypes, typename ...ActualArgTypes>
+static RefPtr<PromiseType>
+InvokeAsync(AbstractThread* aTarget, ThisType* aThisVal, const char* aCallerName,
+            RefPtr<PromiseType>(ThisType::*aMethod)(ArgTypes...), ActualArgTypes&&... aArgs)
+{
+  static_assert(!detail::Any(IsReference<ArgTypes>::value...),
+                "Cannot pass reference types through InvokeAsync, see bug 1313497 if you require it");
+  typedef detail::MethodCall<PromiseType, ThisType, ArgTypes...> MethodCallType;
+  typedef detail::ProxyRunnable<PromiseType, ThisType, ArgTypes...> ProxyRunnableType;
+
+  MethodCallType* methodCall = new MethodCallType(aMethod, aThisVal, Forward<ActualArgTypes>(aArgs)...);
+  RefPtr<typename PromiseType::Private> p = new (typename PromiseType::Private)(aCallerName);
+  RefPtr<ProxyRunnableType> r = new ProxyRunnableType(p, methodCall);
+  MOZ_ASSERT(aTarget->IsDispatchReliable());
+  aTarget->Dispatch(r.forget());
+  return p.forget();
+}
+
+#undef PROMISE_LOG
+#undef PROMISE_ASSERT
+#undef PROMISE_DEBUG
+
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/threads/SharedThreadPool.cpp b/xpcom/threads/SharedThreadPool.cpp
new file mode 100644
index 000000000..9adf6449e
--- /dev/null
+++ b/xpcom/threads/SharedThreadPool.cpp
@@ -0,0 +1,224 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/SharedThreadPool.h"
+#include "mozilla/Monitor.h"
+#include "mozilla/ReentrantMonitor.h"
+#include "mozilla/Services.h"
+#include "mozilla/StaticPtr.h"
+#include "nsDataHashtable.h"
+#include "nsXPCOMCIDInternal.h"
+#include "nsComponentManagerUtils.h"
+#include "nsIObserver.h"
+#include "nsIObserverService.h"
+#ifdef XP_WIN
+#include "ThreadPoolCOMListener.h"
+#endif
+
+namespace mozilla {
+
+// Created and destroyed on the main thread.
+static StaticAutoPtr<ReentrantMonitor> sMonitor;
+
+// Hashtable, maps thread pool name to SharedThreadPool instance.
+// Modified only on the main thread.
+static StaticAutoPtr<nsDataHashtable<nsCStringHashKey, SharedThreadPool*>> sPools;
+
+static already_AddRefed<nsIThreadPool>
+CreateThreadPool(const nsCString& aName);
+
+class SharedThreadPoolShutdownObserver : public nsIObserver
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+protected:
+  virtual ~SharedThreadPoolShutdownObserver() {}
+};
+
+NS_IMPL_ISUPPORTS(SharedThreadPoolShutdownObserver, nsIObserver, nsISupports)
+
+NS_IMETHODIMP
+SharedThreadPoolShutdownObserver::Observe(nsISupports* aSubject, const char *aTopic,
+                                          const char16_t *aData)
+{
+  MOZ_RELEASE_ASSERT(!strcmp(aTopic, "xpcom-shutdown-threads"));
+  SharedThreadPool::SpinUntilEmpty();
+  sMonitor = nullptr;
+  sPools = nullptr;
+  return NS_OK;
+}
+
+void
+SharedThreadPool::InitStatics()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!sMonitor && !sPools);
+  sMonitor = new ReentrantMonitor("SharedThreadPool");
+  sPools = new nsDataHashtable<nsCStringHashKey, SharedThreadPool*>();
+  nsCOMPtr<nsIObserverService> obsService = mozilla::services::GetObserverService();
+  nsCOMPtr<nsIObserver> obs = new SharedThreadPoolShutdownObserver();
+  obsService->AddObserver(obs, "xpcom-shutdown-threads", false);
+}
+
+/* static */
+bool
+SharedThreadPool::IsEmpty()
+{
+  ReentrantMonitorAutoEnter mon(*sMonitor);
+  return !sPools->Count();
+}
+
+/* static */
+void
+SharedThreadPool::SpinUntilEmpty()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  while (!IsEmpty()) {
+    sMonitor->AssertNotCurrentThreadIn();
+    NS_ProcessNextEvent(NS_GetCurrentThread(), true);
+  }
+}
+
+already_AddRefed<SharedThreadPool>
+SharedThreadPool::Get(const nsCString& aName, uint32_t aThreadLimit)
+{
+  MOZ_ASSERT(sMonitor && sPools);
+  ReentrantMonitorAutoEnter mon(*sMonitor);
+  SharedThreadPool* pool = nullptr;
+  nsresult rv;
+  if (!sPools->Get(aName, &pool)) {
+    nsCOMPtr<nsIThreadPool> threadPool(CreateThreadPool(aName));
+    NS_ENSURE_TRUE(threadPool, nullptr);
+    pool = new SharedThreadPool(aName, threadPool);
+
+    // Set the thread and idle limits. Note that we don't rely on the
+    // EnsureThreadLimitIsAtLeast() call below, as the default thread limit
+    // is 4, and if aThreadLimit is less than 4 we'll end up with a pool
+    // with 4 threads rather than what we expected; so we'll have unexpected
+    // behaviour.
+    rv = pool->SetThreadLimit(aThreadLimit);
+    NS_ENSURE_SUCCESS(rv, nullptr);
+
+    rv = pool->SetIdleThreadLimit(aThreadLimit);
+    NS_ENSURE_SUCCESS(rv, nullptr);
+
+    sPools->Put(aName, pool);
+  } else if (NS_FAILED(pool->EnsureThreadLimitIsAtLeast(aThreadLimit))) {
+    NS_WARNING("Failed to set limits on thread pool");
+  }
+
+  MOZ_ASSERT(pool);
+  RefPtr<SharedThreadPool> instance(pool);
+  return instance.forget();
+}
+
+NS_IMETHODIMP_(MozExternalRefCountType) SharedThreadPool::AddRef(void)
+{
+  MOZ_ASSERT(sMonitor);
+  ReentrantMonitorAutoEnter mon(*sMonitor);
+  MOZ_ASSERT(int32_t(mRefCnt) >= 0, "illegal refcnt");
+  nsrefcnt count = ++mRefCnt;
+  NS_LOG_ADDREF(this, count, "SharedThreadPool", sizeof(*this));
+  return count;
+}
+
+NS_IMETHODIMP_(MozExternalRefCountType) SharedThreadPool::Release(void)
+{
+  MOZ_ASSERT(sMonitor);
+  ReentrantMonitorAutoEnter mon(*sMonitor);
+  nsrefcnt count = --mRefCnt;
+  NS_LOG_RELEASE(this, count, "SharedThreadPool");
+  if (count) {
+    return count;
+  }
+
+  // Remove SharedThreadPool from table of pools.
+  sPools->Remove(mName);
+  MOZ_ASSERT(!sPools->Get(mName));
+
+  // Dispatch an event to the main thread to call Shutdown() on
+  // the nsIThreadPool. The Runnable here will add a refcount to the pool,
+  // and when the Runnable releases the nsIThreadPool it will be deleted.
+  NS_DispatchToMainThread(NewRunnableMethod(mPool, &nsIThreadPool::Shutdown));
+
+  // Stabilize refcount, so that if something in the dtor QIs, it won't explode.
+  mRefCnt = 1;
+  delete this;
+  return 0;
+}
+
+NS_IMPL_QUERY_INTERFACE(SharedThreadPool, nsIThreadPool, nsIEventTarget)
+
+SharedThreadPool::SharedThreadPool(const nsCString& aName,
+                                   nsIThreadPool* aPool)
+  : mName(aName)
+  , mPool(aPool)
+  , mRefCnt(0)
+{
+  MOZ_COUNT_CTOR(SharedThreadPool);
+  mEventTarget = do_QueryInterface(aPool);
+}
+
+SharedThreadPool::~SharedThreadPool()
+{
+  MOZ_COUNT_DTOR(SharedThreadPool);
+}
+
+nsresult
+SharedThreadPool::EnsureThreadLimitIsAtLeast(uint32_t aLimit)
+{
+  // We limit the number of threads that we use. Note that we
+  // set the thread limit to the same as the idle limit so that we're not
+  // constantly creating and destroying threads (see Bug 881954). When the
+  // thread pool threads shutdown they dispatch an event to the main thread
+  // to call nsIThread::Shutdown(), and if we're very busy that can take a
+  // while to run, and we end up with dozens of extra threads. Note that
+  // threads that are idle for 60 seconds are shutdown naturally.
+  uint32_t existingLimit = 0;
+  nsresult rv;
+
+  rv = mPool->GetThreadLimit(&existingLimit);
+  NS_ENSURE_SUCCESS(rv, rv);
+  if (aLimit > existingLimit) {
+    rv = mPool->SetThreadLimit(aLimit);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  rv = mPool->GetIdleThreadLimit(&existingLimit);
+  NS_ENSURE_SUCCESS(rv, rv);
+  if (aLimit > existingLimit) {
+    rv = mPool->SetIdleThreadLimit(aLimit);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  return NS_OK;
+}
+
+static already_AddRefed<nsIThreadPool>
+CreateThreadPool(const nsCString& aName)
+{
+  nsresult rv;
+  nsCOMPtr<nsIThreadPool> pool = do_CreateInstance(NS_THREADPOOL_CONTRACTID, &rv);
+  NS_ENSURE_SUCCESS(rv, nullptr);
+
+  rv = pool->SetName(aName);
+  NS_ENSURE_SUCCESS(rv, nullptr);
+
+  rv = pool->SetThreadStackSize(SharedThreadPool::kStackSize);
+  NS_ENSURE_SUCCESS(rv, nullptr);
+
+#ifdef XP_WIN
+  // Ensure MSCOM is initialized on the thread pools threads.
+  nsCOMPtr<nsIThreadPoolListener> listener = new MSCOMInitThreadPoolListener();
+  rv = pool->SetListener(listener);
+  NS_ENSURE_SUCCESS(rv, nullptr);
+#endif
+
+  return pool.forget();
+}
+
+} // namespace mozilla
diff --git a/xpcom/threads/SharedThreadPool.h b/xpcom/threads/SharedThreadPool.h
new file mode 100644
index 000000000..185b9e76f
--- /dev/null
+++ b/xpcom/threads/SharedThreadPool.h
@@ -0,0 +1,129 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef SharedThreadPool_h_
+#define SharedThreadPool_h_
+
+#include <queue>
+#include "mozilla/RefPtr.h"
+#include "nsThreadUtils.h"
+#include "nsIThreadManager.h"
+#include "nsIThreadPool.h"
+#include "nsISupports.h"
+#include "nsISupportsImpl.h"
+#include "nsCOMPtr.h"
+
+namespace mozilla {
+
+// Wrapper that makes an nsIThreadPool a singleton, and provides a
+// consistent threadsafe interface to get instances. Callers simply get a
+// SharedThreadPool by the name of its nsIThreadPool. All get requests of
+// the same name get the same SharedThreadPool. Users must store a reference
+// to the pool, and when the last reference to a SharedThreadPool is dropped
+// the pool is shutdown and deleted. Users aren't required to manually
+// shutdown the pool, and can release references on any thread. This can make
+// it significantly easier to use thread pools, because the caller doesn't need
+// to worry about joining and tearing it down.
+//
+// On Windows all threads in the pool have MSCOM initialized with
+// COINIT_MULTITHREADED. Note that not all users of MSCOM use this mode see [1],
+// and mixing MSCOM objects between the two is terrible for performance, and can
+// cause some functions to fail. So be careful when using Win32 APIs on a
+// SharedThreadPool, and avoid sharing objects if at all possible.
+//
+// [1] https://dxr.mozilla.org/mozilla-central/search?q=coinitialize&redirect=false
+class SharedThreadPool : public nsIThreadPool
+{
+public:
+
+  // Gets (possibly creating) the shared thread pool singleton instance with
+  // thread pool named aName.
+  static already_AddRefed<SharedThreadPool> Get(const nsCString& aName,
+                                            uint32_t aThreadLimit = 4);
+
+  // We implement custom threadsafe AddRef/Release pair, that destroys the
+  // the shared pool singleton when the refcount drops to 0. The addref/release
+  // are implemented using locking, so it's not recommended that you use them
+  // in a tight loop.
+  NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr) override;
+  NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override;
+  NS_IMETHOD_(MozExternalRefCountType) Release(void) override;
+
+  // Forward behaviour to wrapped thread pool implementation.
+  NS_FORWARD_SAFE_NSITHREADPOOL(mPool);
+
+  // Call this when dispatching from an event on the same
+  // threadpool that is about to complete. We should not create a new thread
+  // in that case since a thread is about to become idle.
+  nsresult DispatchFromEndOfTaskInThisPool(nsIRunnable *event)
+  {
+    return Dispatch(event, NS_DISPATCH_AT_END);
+  }
+
+  NS_IMETHOD DispatchFromScript(nsIRunnable *event, uint32_t flags) override {
+      return Dispatch(event, flags);
+  }
+
+  NS_IMETHOD Dispatch(already_AddRefed<nsIRunnable> event, uint32_t flags) override
+    { return !mEventTarget ? NS_ERROR_NULL_POINTER : mEventTarget->Dispatch(Move(event), flags); }
+
+  NS_IMETHOD DelayedDispatch(already_AddRefed<nsIRunnable>, uint32_t) override
+    { return NS_ERROR_NOT_IMPLEMENTED; }
+
+  using nsIEventTarget::Dispatch;
+
+  NS_IMETHOD IsOnCurrentThread(bool *_retval) override { return !mEventTarget ? NS_ERROR_NULL_POINTER : mEventTarget->IsOnCurrentThread(_retval); }
+
+  // Creates necessary statics. Called once at startup.
+  static void InitStatics();
+
+  // Spins the event loop until all thread pools are shutdown.
+  // *Must* be called on the main thread.
+  static void SpinUntilEmpty();
+
+#if defined(MOZ_ASAN)
+  // Use the system default in ASAN builds, because the default is assumed to be
+  // larger than the size we want to use and is hopefully sufficient for ASAN.
+  static const uint32_t kStackSize = nsIThreadManager::DEFAULT_STACK_SIZE;
+#elif defined(XP_WIN) || defined(XP_MACOSX) || defined(LINUX)
+  static const uint32_t kStackSize = (256 * 1024);
+#else
+  // All other platforms use their system defaults.
+  static const uint32_t kStackSize = nsIThreadManager::DEFAULT_STACK_SIZE;
+#endif
+
+private:
+
+  // Returns whether there are no pools in existence at the moment.
+  static bool IsEmpty();
+
+  // Creates a singleton SharedThreadPool wrapper around aPool.
+  // aName is the name of the aPool, and is used to lookup the
+  // SharedThreadPool in the hash table of all created pools.
+  SharedThreadPool(const nsCString& aName,
+                   nsIThreadPool* aPool);
+  virtual ~SharedThreadPool();
+
+  nsresult EnsureThreadLimitIsAtLeast(uint32_t aThreadLimit);
+
+  // Name of mPool.
+  const nsCString mName;
+
+  // Thread pool being wrapped.
+  nsCOMPtr<nsIThreadPool> mPool;
+
+  // Refcount. We implement custom ref counting so that the thread pool is
+  // shutdown in a threadsafe manner and singletonness is preserved.
+  nsrefcnt mRefCnt;
+
+  // mPool QI'd to nsIEventTarget. We cache this, so that we can use
+  // NS_FORWARD_SAFE_NSIEVENTTARGET above.
+  nsCOMPtr<nsIEventTarget> mEventTarget;
+};
+
+} // namespace mozilla
+
+#endif // SharedThreadPool_h_
diff --git a/xpcom/threads/StateMirroring.h b/xpcom/threads/StateMirroring.h
new file mode 100644
index 000000000..87d94ba74
--- /dev/null
+++ b/xpcom/threads/StateMirroring.h
@@ -0,0 +1,378 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#if !defined(StateMirroring_h_)
+#define StateMirroring_h_
+
+#include "mozilla/Maybe.h"
+#include "mozilla/MozPromise.h"
+#include "mozilla/StateWatching.h"
+#include "mozilla/TaskDispatcher.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/Unused.h"
+
+#include "mozilla/Logging.h"
+#include "nsISupportsImpl.h"
+
+/*
+ * The state-mirroring machinery allows pieces of interesting state to be
+ * observed on multiple thread without locking. The basic strategy is to track
+ * changes in a canonical value and post updates to other threads that hold
+ * mirrors for that value.
+ *
+ * One problem with the naive implementation of such a system is that some pieces
+ * of state need to be updated atomically, and certain other operations need to
+ * wait for these atomic updates to complete before executing. The state-mirroring
+ * machinery solves this problem by requiring that its owner thread uses tail
+ * dispatch, and posting state update events (which should always be run first by
+ * TaskDispatcher implementations) to that tail dispatcher. This ensures that
+ * state changes are always atomic from the perspective of observing threads.
+ *
+ * Given that state-mirroring is an automatic background process, we try to avoid
+ * burdening the caller with worrying too much about teardown. To that end, we
+ * don't assert dispatch success for any of the notifications, and assume that
+ * any canonical or mirror owned by a thread for whom dispatch fails will soon
+ * be disconnected by its holder anyway.
+ *
+ * Given that semantics may change and comments tend to go out of date, we
+ * deliberately don't provide usage examples here. Grep around to find them.
+ */
+
+namespace mozilla {
+
+// Mirror<T> and Canonical<T> inherit WatchTarget, so we piggy-back on the
+// logging that WatchTarget already does. Given that, it makes sense to share
+// the same log module.
+#define MIRROR_LOG(x, ...) \
+  MOZ_ASSERT(gStateWatchingLog); \
+  MOZ_LOG(gStateWatchingLog, LogLevel::Debug, (x, ##__VA_ARGS__))
+
+template<typename T> class AbstractMirror;
+
+/*
+ * AbstractCanonical is a superclass from which all Canonical values must
+ * inherit. It serves as the interface of operations which may be performed (via
+ * asynchronous dispatch) by other threads, in particular by the corresponding
+ * Mirror value.
+ */
+template<typename T>
+class AbstractCanonical
+{
+public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(AbstractCanonical)
+  AbstractCanonical(AbstractThread* aThread) : mOwnerThread(aThread) {}
+  virtual void AddMirror(AbstractMirror<T>* aMirror) = 0;
+  virtual void RemoveMirror(AbstractMirror<T>* aMirror) = 0;
+
+  AbstractThread* OwnerThread() const { return mOwnerThread; }
+protected:
+  virtual ~AbstractCanonical() {}
+  RefPtr<AbstractThread> mOwnerThread;
+};
+
+/*
+ * AbstractMirror is a superclass from which all Mirror values must
+ * inherit. It serves as the interface of operations which may be performed (via
+ * asynchronous dispatch) by other threads, in particular by the corresponding
+ * Canonical value.
+ */
+template<typename T>
+class AbstractMirror
+{
+public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(AbstractMirror)
+  AbstractMirror(AbstractThread* aThread) : mOwnerThread(aThread) {}
+  virtual void UpdateValue(const T& aNewValue) = 0;
+  virtual void NotifyDisconnected() = 0;
+
+  AbstractThread* OwnerThread() const { return mOwnerThread; }
+protected:
+  virtual ~AbstractMirror() {}
+  RefPtr<AbstractThread> mOwnerThread;
+};
+
+/*
+ * Canonical<T> is a wrapper class that allows a given value to be mirrored by other
+ * threads. It maintains a list of active mirrors, and queues updates for them
+ * when the internal value changes. When changing the value, the caller needs to
+ * pass a TaskDispatcher object, which fires the updates at the appropriate time.
+ * Canonical<T> is also a WatchTarget, and may be set up to trigger other routines
+ * (on the same thread) when the canonical value changes.
+ *
+ * Canonical<T> is intended to be used as a member variable, so it doesn't actually
+ * inherit AbstractCanonical<T> (a refcounted type). Rather, it contains an inner
+ * class called |Impl| that implements most of the interesting logic.
+ */
+template<typename T>
+class Canonical
+{
+public:
+  Canonical(AbstractThread* aThread, const T& aInitialValue, const char* aName)
+  {
+    mImpl = new Impl(aThread, aInitialValue, aName);
+  }
+
+
+  ~Canonical() {}
+
+private:
+  class Impl : public AbstractCanonical<T>, public WatchTarget
+  {
+  public:
+    using AbstractCanonical<T>::OwnerThread;
+
+    Impl(AbstractThread* aThread, const T& aInitialValue, const char* aName)
+      : AbstractCanonical<T>(aThread), WatchTarget(aName), mValue(aInitialValue)
+    {
+      MIRROR_LOG("%s [%p] initialized", mName, this);
+      MOZ_ASSERT(aThread->SupportsTailDispatch(), "Can't get coherency without tail dispatch");
+    }
+
+    void AddMirror(AbstractMirror<T>* aMirror) override
+    {
+      MIRROR_LOG("%s [%p] adding mirror %p", mName, this, aMirror);
+      MOZ_ASSERT(OwnerThread()->IsCurrentThreadIn());
+      MOZ_ASSERT(!mMirrors.Contains(aMirror));
+      mMirrors.AppendElement(aMirror);
+      aMirror->OwnerThread()->DispatchStateChange(MakeNotifier(aMirror));
+    }
+
+    void RemoveMirror(AbstractMirror<T>* aMirror) override
+    {
+      MIRROR_LOG("%s [%p] removing mirror %p", mName, this, aMirror);
+      MOZ_ASSERT(OwnerThread()->IsCurrentThreadIn());
+      MOZ_ASSERT(mMirrors.Contains(aMirror));
+      mMirrors.RemoveElement(aMirror);
+    }
+
+    void DisconnectAll()
+    {
+      MIRROR_LOG("%s [%p] Disconnecting all mirrors", mName, this);
+      for (size_t i = 0; i < mMirrors.Length(); ++i) {
+        mMirrors[i]->OwnerThread()->Dispatch(NewRunnableMethod(mMirrors[i],
+                                                               &AbstractMirror<T>::NotifyDisconnected),
+                                             AbstractThread::DontAssertDispatchSuccess);
+      }
+      mMirrors.Clear();
+    }
+
+    operator const T&()
+    {
+      MOZ_ASSERT(OwnerThread()->IsCurrentThreadIn());
+      return mValue;
+    }
+
+    void Set(const T& aNewValue)
+    {
+      MOZ_ASSERT(OwnerThread()->IsCurrentThreadIn());
+
+      if (aNewValue == mValue) {
+        return;
+      }
+
+      // Notify same-thread watchers. The state watching machinery will make sure
+      // that notifications run at the right time.
+      NotifyWatchers();
+
+      // Check if we've already got a pending update. If so we won't schedule another
+      // one.
+      bool alreadyNotifying = mInitialValue.isSome();
+
+      // Stash the initial value if needed, then update to the new value.
+      if (mInitialValue.isNothing()) {
+        mInitialValue.emplace(mValue);
+      }
+      mValue = aNewValue;
+
+      // We wait until things have stablized before sending state updates so that
+      // we can avoid sending multiple updates, and possibly avoid sending any
+      // updates at all if the value ends up where it started.
+      if (!alreadyNotifying) {
+        AbstractThread::DispatchDirectTask(NewRunnableMethod(this, &Impl::DoNotify));
+      }
+    }
+
+    Impl& operator=(const T& aNewValue) { Set(aNewValue); return *this; }
+    Impl& operator=(const Impl& aOther) { Set(aOther); return *this; }
+    Impl(const Impl& aOther) = delete;
+
+  protected:
+    ~Impl() { MOZ_DIAGNOSTIC_ASSERT(mMirrors.IsEmpty()); }
+
+  private:
+    void DoNotify()
+    {
+      MOZ_ASSERT(OwnerThread()->IsCurrentThreadIn());
+      MOZ_ASSERT(mInitialValue.isSome());
+      bool same = mInitialValue.ref() == mValue;
+      mInitialValue.reset();
+
+      if (same) {
+        MIRROR_LOG("%s [%p] unchanged - not sending update", mName, this);
+        return;
+      }
+
+      for (size_t i = 0; i < mMirrors.Length(); ++i) {
+        mMirrors[i]->OwnerThread()->DispatchStateChange(MakeNotifier(mMirrors[i]));
+      }
+    }
+
+    already_AddRefed<nsIRunnable> MakeNotifier(AbstractMirror<T>* aMirror)
+    {
+      return NewRunnableMethod<T>(aMirror, &AbstractMirror<T>::UpdateValue, mValue);;
+    }
+
+    T mValue;
+    Maybe<T> mInitialValue;
+    nsTArray<RefPtr<AbstractMirror<T>>> mMirrors;
+  };
+public:
+
+  // NB: Because mirror-initiated disconnection can race with canonical-
+  // initiated disconnection, a canonical should never be reinitialized.
+  // Forward control operations to the Impl.
+  void DisconnectAll() { return mImpl->DisconnectAll(); }
+
+  // Access to the Impl.
+  operator Impl&() { return *mImpl; }
+  Impl* operator&() { return mImpl; }
+
+  // Access to the T.
+  const T& Ref() const { return *mImpl; }
+  operator const T&() const { return Ref(); }
+  void Set(const T& aNewValue) { mImpl->Set(aNewValue); }
+  Canonical& operator=(const T& aNewValue) { Set(aNewValue); return *this; }
+  Canonical& operator=(const Canonical& aOther) { Set(aOther); return *this; }
+  Canonical(const Canonical& aOther) = delete;
+
+private:
+  RefPtr<Impl> mImpl;
+};
+
+/*
+ * Mirror<T> is a wrapper class that allows a given value to mirror that of a
+ * Canonical<T> owned by another thread. It registers itself with a Canonical<T>,
+ * and is periodically updated with new values. Mirror<T> is also a WatchTarget,
+ * and may be set up to trigger other routines (on the same thread) when the
+ * mirrored value changes.
+ *
+ * Mirror<T> is intended to be used as a member variable, so it doesn't actually
+ * inherit AbstractMirror<T> (a refcounted type). Rather, it contains an inner
+ * class called |Impl| that implements most of the interesting logic.
+ */
+template<typename T>
+class Mirror
+{
+public:
+  Mirror(AbstractThread* aThread, const T& aInitialValue, const char* aName)
+  {
+    mImpl = new Impl(aThread, aInitialValue, aName);
+  }
+
+  ~Mirror()
+  {
+    // As a member of complex objects, a Mirror<T> may be destroyed on a
+    // different thread than its owner, or late in shutdown during CC. Given
+    // that, we require manual disconnection so that callers can put things in
+    // the right place.
+    MOZ_DIAGNOSTIC_ASSERT(!mImpl->IsConnected());
+  }
+
+private:
+  class Impl : public AbstractMirror<T>, public WatchTarget
+  {
+  public:
+    using AbstractMirror<T>::OwnerThread;
+
+    Impl(AbstractThread* aThread, const T& aInitialValue, const char* aName)
+      : AbstractMirror<T>(aThread), WatchTarget(aName), mValue(aInitialValue)
+    {
+      MIRROR_LOG("%s [%p] initialized", mName, this);
+      MOZ_ASSERT(aThread->SupportsTailDispatch(), "Can't get coherency without tail dispatch");
+    }
+
+    operator const T&()
+    {
+      MOZ_ASSERT(OwnerThread()->IsCurrentThreadIn());
+      return mValue;
+    }
+
+    virtual void UpdateValue(const T& aNewValue) override
+    {
+      MOZ_ASSERT(OwnerThread()->IsCurrentThreadIn());
+      if (mValue != aNewValue) {
+        mValue = aNewValue;
+        WatchTarget::NotifyWatchers();
+      }
+    }
+
+    virtual void NotifyDisconnected() override
+    {
+      MIRROR_LOG("%s [%p] Notifed of disconnection from %p", mName, this, mCanonical.get());
+      MOZ_ASSERT(OwnerThread()->IsCurrentThreadIn());
+      mCanonical = nullptr;
+    }
+
+    bool IsConnected() const { return !!mCanonical; }
+
+    void Connect(AbstractCanonical<T>* aCanonical)
+    {
+      MIRROR_LOG("%s [%p] Connecting to %p", mName, this, aCanonical);
+      MOZ_ASSERT(OwnerThread()->IsCurrentThreadIn());
+      MOZ_ASSERT(!IsConnected());
+      MOZ_ASSERT(OwnerThread()->RequiresTailDispatch(aCanonical->OwnerThread()), "Can't get coherency without tail dispatch");
+
+      nsCOMPtr<nsIRunnable> r = NewRunnableMethod<StorensRefPtrPassByPtr<AbstractMirror<T>>>
+                                  (aCanonical, &AbstractCanonical<T>::AddMirror, this);
+      aCanonical->OwnerThread()->Dispatch(r.forget(), AbstractThread::DontAssertDispatchSuccess);
+      mCanonical = aCanonical;
+    }
+  public:
+
+    void DisconnectIfConnected()
+    {
+      MOZ_ASSERT(OwnerThread()->IsCurrentThreadIn());
+      if (!IsConnected()) {
+        return;
+      }
+
+      MIRROR_LOG("%s [%p] Disconnecting from %p", mName, this, mCanonical.get());
+      nsCOMPtr<nsIRunnable> r = NewRunnableMethod<StorensRefPtrPassByPtr<AbstractMirror<T>>>
+                                  (mCanonical, &AbstractCanonical<T>::RemoveMirror, this);
+      mCanonical->OwnerThread()->Dispatch(r.forget(), AbstractThread::DontAssertDispatchSuccess);
+      mCanonical = nullptr;
+    }
+
+  protected:
+    ~Impl() { MOZ_DIAGNOSTIC_ASSERT(!IsConnected()); }
+
+  private:
+    T mValue;
+    RefPtr<AbstractCanonical<T>> mCanonical;
+  };
+public:
+
+  // Forward control operations to the Impl<T>.
+  void Connect(AbstractCanonical<T>* aCanonical) { mImpl->Connect(aCanonical); }
+  void DisconnectIfConnected() { mImpl->DisconnectIfConnected(); }
+
+  // Access to the Impl<T>.
+  operator Impl&() { return *mImpl; }
+  Impl* operator&() { return mImpl; }
+
+  // Access to the T.
+  const T& Ref() const { return *mImpl; }
+  operator const T&() const { return Ref(); }
+
+private:
+  RefPtr<Impl> mImpl;
+};
+
+#undef MIRROR_LOG
+
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/threads/StateWatching.h b/xpcom/threads/StateWatching.h
new file mode 100644
index 000000000..99d521603
--- /dev/null
+++ b/xpcom/threads/StateWatching.h
@@ -0,0 +1,317 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#if !defined(StateWatching_h_)
+#define StateWatching_h_
+
+#include "mozilla/AbstractThread.h"
+#include "mozilla/Logging.h"
+#include "mozilla/TaskDispatcher.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/Unused.h"
+
+#include "nsISupportsImpl.h"
+
+/*
+ * The state-watching machinery automates the process of responding to changes
+ * in various pieces of state.
+ *
+ * A standard programming pattern is as follows:
+ *
+ * mFoo = ...;
+ * NotifyStuffChanged();
+ * ...
+ * mBar = ...;
+ * NotifyStuffChanged();
+ *
+ * This pattern is error-prone and difficult to audit because it requires the
+ * programmer to manually trigger the update routine. This can be especially
+ * problematic when the update routine depends on numerous pieces of state, and
+ * when that state is modified across a variety of helper methods. In these
+ * cases the responsibility for invoking the routine is often unclear, causing
+ * developers to scatter calls to it like pixie dust. This can result in
+ * duplicate invocations (which is wasteful) and missing invocations in corner-
+ * cases (which is a source of bugs).
+ *
+ * This file provides a set of primitives that automatically handle updates and
+ * allow the programmers to explicitly construct a graph of state dependencies.
+ * When used correctly, it eliminates the guess-work and wasted cycles described
+ * above.
+ *
+ * There are two basic pieces:
+ *   (1) Objects that can be watched for updates. These inherit WatchTarget.
+ *   (2) Objects that receive objects and trigger processing. These inherit
+ *       AbstractWatcher. In the current machinery, these exist only internally
+ *       within the WatchManager, though that could change.
+ *
+ * Note that none of this machinery is thread-safe - it must all happen on the
+ * same owning thread. To solve multi-threaded use-cases, use state mirroring
+ * and watch the mirrored value.
+ *
+ * Given that semantics may change and comments tend to go out of date, we
+ * deliberately don't provide usage examples here. Grep around to find them.
+ */
+
+namespace mozilla {
+
+extern LazyLogModule gStateWatchingLog;
+
+#define WATCH_LOG(x, ...) \
+  MOZ_LOG(gStateWatchingLog, LogLevel::Debug, (x, ##__VA_ARGS__))
+
+/*
+ * AbstractWatcher is a superclass from which all watchers must inherit.
+ */
+class AbstractWatcher
+{
+public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(AbstractWatcher)
+  AbstractWatcher() : mDestroyed(false) {}
+  bool IsDestroyed() { return mDestroyed; }
+  virtual void Notify() = 0;
+
+protected:
+  virtual ~AbstractWatcher() { MOZ_ASSERT(mDestroyed); }
+  bool mDestroyed;
+};
+
+/*
+ * WatchTarget is a superclass from which all watchable things must inherit.
+ * Unlike AbstractWatcher, it is a fully-implemented Mix-in, and the subclass
+ * needs only to invoke NotifyWatchers when something changes.
+ *
+ * The functionality that this class provides is not threadsafe, and should only
+ * be used on the thread that owns that WatchTarget.
+ */
+class WatchTarget
+{
+public:
+  explicit WatchTarget(const char* aName) : mName(aName) {}
+
+  void AddWatcher(AbstractWatcher* aWatcher)
+  {
+    MOZ_ASSERT(!mWatchers.Contains(aWatcher));
+    mWatchers.AppendElement(aWatcher);
+  }
+
+  void RemoveWatcher(AbstractWatcher* aWatcher)
+  {
+    MOZ_ASSERT(mWatchers.Contains(aWatcher));
+    mWatchers.RemoveElement(aWatcher);
+  }
+
+protected:
+  void NotifyWatchers()
+  {
+    WATCH_LOG("%s[%p] notifying watchers\n", mName, this);
+    PruneWatchers();
+    for (size_t i = 0; i < mWatchers.Length(); ++i) {
+      mWatchers[i]->Notify();
+    }
+  }
+
+private:
+  // We don't have Watchers explicitly unregister themselves when they die,
+  // because then they'd need back-references to all the WatchTargets they're
+  // subscribed to, and WatchTargets aren't reference-counted. So instead we
+  // just prune dead ones at appropriate times, which works just fine.
+  void PruneWatchers()
+  {
+    for (int i = mWatchers.Length() - 1; i >= 0; --i) {
+      if (mWatchers[i]->IsDestroyed()) {
+        mWatchers.RemoveElementAt(i);
+      }
+    }
+  }
+
+  nsTArray<RefPtr<AbstractWatcher>> mWatchers;
+
+protected:
+  const char* mName;
+};
+
+/*
+ * Watchable is a wrapper class that turns any primitive into a WatchTarget.
+ */
+template<typename T>
+class Watchable : public WatchTarget
+{
+public:
+  Watchable(const T& aInitialValue, const char* aName)
+    : WatchTarget(aName), mValue(aInitialValue) {}
+
+  const T& Ref() const { return mValue; }
+  operator const T&() const { return Ref(); }
+  Watchable& operator=(const T& aNewValue)
+  {
+    if (aNewValue != mValue) {
+      mValue = aNewValue;
+      NotifyWatchers();
+    }
+
+    return *this;
+  }
+
+private:
+  Watchable(const Watchable& aOther); // Not implemented
+  Watchable& operator=(const Watchable& aOther); // Not implemented
+
+  T mValue;
+};
+
+// Manager class for state-watching. Declare one of these in any class for which
+// you want to invoke method callbacks.
+//
+// Internally, WatchManager maintains one AbstractWatcher per callback method.
+// Consumers invoke Watch/Unwatch on a particular (WatchTarget, Callback) tuple.
+// This causes an AbstractWatcher for |Callback| to be instantiated if it doesn't
+// already exist, and registers it with |WatchTarget|.
+//
+// Using Direct Tasks on the TailDispatcher, WatchManager ensures that we fire
+// watch callbacks no more than once per task, once all other operations for that
+// task have been completed.
+//
+// WatchManager<OwnerType> is intended to be declared as a member of |OwnerType|
+// objects. Given that, it and its owned objects can't hold permanent strong refs to
+// the owner, since that would keep the owner alive indefinitely. Instead, it
+// _only_ holds strong refs while waiting for Direct Tasks to fire. This ensures
+// that everything is kept alive just long enough.
+template <typename OwnerType>
+class WatchManager
+{
+public:
+  typedef void(OwnerType::*CallbackMethod)();
+  explicit WatchManager(OwnerType* aOwner, AbstractThread* aOwnerThread)
+    : mOwner(aOwner), mOwnerThread(aOwnerThread) {}
+
+  ~WatchManager()
+  {
+    if (!IsShutdown()) {
+      Shutdown();
+    }
+  }
+
+  bool IsShutdown() const { return !mOwner; }
+
+  // Shutdown needs to happen on mOwnerThread. If the WatchManager will be
+  // destroyed on a different thread, Shutdown() must be called manually.
+  void Shutdown()
+  {
+    MOZ_ASSERT(mOwnerThread->IsCurrentThreadIn());
+    for (size_t i = 0; i < mWatchers.Length(); ++i) {
+      mWatchers[i]->Destroy();
+    }
+    mWatchers.Clear();
+    mOwner = nullptr;
+  }
+
+  void Watch(WatchTarget& aTarget, CallbackMethod aMethod)
+  {
+    MOZ_ASSERT(mOwnerThread->IsCurrentThreadIn());
+    aTarget.AddWatcher(&EnsureWatcher(aMethod));
+  }
+
+  void Unwatch(WatchTarget& aTarget, CallbackMethod aMethod)
+  {
+    MOZ_ASSERT(mOwnerThread->IsCurrentThreadIn());
+    PerCallbackWatcher* watcher = GetWatcher(aMethod);
+    MOZ_ASSERT(watcher);
+    aTarget.RemoveWatcher(watcher);
+  }
+
+  void ManualNotify(CallbackMethod aMethod)
+  {
+    MOZ_ASSERT(mOwnerThread->IsCurrentThreadIn());
+    PerCallbackWatcher* watcher = GetWatcher(aMethod);
+    MOZ_ASSERT(watcher);
+    watcher->Notify();
+  }
+
+private:
+  class PerCallbackWatcher : public AbstractWatcher
+  {
+  public:
+    PerCallbackWatcher(OwnerType* aOwner, AbstractThread* aOwnerThread, CallbackMethod aMethod)
+      : mOwner(aOwner), mOwnerThread(aOwnerThread), mCallbackMethod(aMethod) {}
+
+    void Destroy()
+    {
+      MOZ_ASSERT(mOwnerThread->IsCurrentThreadIn());
+      mDestroyed = true;
+      mOwner = nullptr;
+    }
+
+    void Notify() override
+    {
+      MOZ_ASSERT(mOwnerThread->IsCurrentThreadIn());
+      MOZ_DIAGNOSTIC_ASSERT(mOwner, "mOwner is only null after destruction, "
+                                    "at which point we shouldn't be notified");
+      if (mStrongRef) {
+        // We've already got a notification job in the pipe.
+        return;
+      }
+      mStrongRef = mOwner; // Hold the owner alive while notifying.
+
+      // Queue up our notification jobs to run in a stable state.
+      mOwnerThread->TailDispatcher().AddDirectTask(NewRunnableMethod(this, &PerCallbackWatcher::DoNotify));
+    }
+
+    bool CallbackMethodIs(CallbackMethod aMethod) const
+    {
+      return mCallbackMethod == aMethod;
+    }
+
+  private:
+    ~PerCallbackWatcher() {}
+
+    void DoNotify()
+    {
+      MOZ_ASSERT(mOwnerThread->IsCurrentThreadIn());
+      MOZ_ASSERT(mStrongRef);
+      RefPtr<OwnerType> ref = mStrongRef.forget();
+      if (!mDestroyed) {
+        ((*ref).*mCallbackMethod)();
+      }
+    }
+
+    OwnerType* mOwner; // Never null.
+    RefPtr<OwnerType> mStrongRef; // Only non-null when notifying.
+    RefPtr<AbstractThread> mOwnerThread;
+    CallbackMethod mCallbackMethod;
+  };
+
+  PerCallbackWatcher* GetWatcher(CallbackMethod aMethod)
+  {
+    MOZ_ASSERT(mOwnerThread->IsCurrentThreadIn());
+    for (size_t i = 0; i < mWatchers.Length(); ++i) {
+      if (mWatchers[i]->CallbackMethodIs(aMethod)) {
+        return mWatchers[i];
+      }
+    }
+    return nullptr;
+  }
+
+  PerCallbackWatcher& EnsureWatcher(CallbackMethod aMethod)
+  {
+    MOZ_ASSERT(mOwnerThread->IsCurrentThreadIn());
+    PerCallbackWatcher* watcher = GetWatcher(aMethod);
+    if (watcher) {
+      return *watcher;
+    }
+    watcher = mWatchers.AppendElement(new PerCallbackWatcher(mOwner, mOwnerThread, aMethod))->get();
+    return *watcher;
+  }
+
+  nsTArray<RefPtr<PerCallbackWatcher>> mWatchers;
+  OwnerType* mOwner;
+  RefPtr<AbstractThread> mOwnerThread;
+};
+
+#undef WATCH_LOG
+
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/threads/SyncRunnable.h b/xpcom/threads/SyncRunnable.h
new file mode 100644
index 000000000..d96bac7ba
--- /dev/null
+++ b/xpcom/threads/SyncRunnable.h
@@ -0,0 +1,129 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_SyncRunnable_h
+#define mozilla_SyncRunnable_h
+
+#include "nsThreadUtils.h"
+#include "mozilla/AbstractThread.h"
+#include "mozilla/Monitor.h"
+#include "mozilla/Move.h"
+
+namespace mozilla {
+
+/**
+ * This class will wrap a nsIRunnable and dispatch it to the main thread
+ * synchronously. This is different from nsIEventTarget.DISPATCH_SYNC:
+ * this class does not spin the event loop waiting for the event to be
+ * dispatched. This means that you don't risk reentrance from pending
+ * messages, but you must be sure that the target thread does not ever block
+ * on this thread, or else you will deadlock.
+ *
+ * Typical usage:
+ * RefPtr<SyncRunnable> sr = new SyncRunnable(new myrunnable...());
+ * sr->DispatchToThread(t);
+ *
+ * We also provide a convenience wrapper:
+ * SyncRunnable::DispatchToThread(new myrunnable...());
+ *
+ */
+class SyncRunnable : public Runnable
+{
+public:
+  explicit SyncRunnable(nsIRunnable* aRunnable)
+    : mRunnable(aRunnable)
+    , mMonitor("SyncRunnable")
+    , mDone(false)
+  {
+  }
+
+  explicit SyncRunnable(already_AddRefed<nsIRunnable> aRunnable)
+    : mRunnable(Move(aRunnable))
+    , mMonitor("SyncRunnable")
+    , mDone(false)
+  {
+  }
+
+  void DispatchToThread(nsIEventTarget* aThread, bool aForceDispatch = false)
+  {
+    nsresult rv;
+    bool on;
+
+    if (!aForceDispatch) {
+      rv = aThread->IsOnCurrentThread(&on);
+      MOZ_ASSERT(NS_SUCCEEDED(rv));
+      if (NS_SUCCEEDED(rv) && on) {
+        mRunnable->Run();
+        return;
+      }
+    }
+
+    rv = aThread->Dispatch(this, NS_DISPATCH_NORMAL);
+    if (NS_SUCCEEDED(rv)) {
+      mozilla::MonitorAutoLock lock(mMonitor);
+      while (!mDone) {
+        lock.Wait();
+      }
+    }
+  }
+
+  void DispatchToThread(AbstractThread* aThread, bool aForceDispatch = false)
+  {
+    if (!aForceDispatch && aThread->IsCurrentThreadIn()) {
+      mRunnable->Run();
+      return;
+    }
+
+    // Check we don't have tail dispatching here. Otherwise we will deadlock
+    // ourself when spinning the loop below.
+    MOZ_ASSERT(!aThread->RequiresTailDispatchFromCurrentThread());
+
+    aThread->Dispatch(RefPtr<nsIRunnable>(this).forget());
+    mozilla::MonitorAutoLock lock(mMonitor);
+    while (!mDone) {
+      lock.Wait();
+    }
+  }
+
+  static void DispatchToThread(nsIEventTarget* aThread,
+                               nsIRunnable* aRunnable,
+                               bool aForceDispatch = false)
+  {
+    RefPtr<SyncRunnable> s(new SyncRunnable(aRunnable));
+    s->DispatchToThread(aThread, aForceDispatch);
+  }
+
+  static void DispatchToThread(AbstractThread* aThread,
+                               nsIRunnable* aRunnable,
+                               bool aForceDispatch = false)
+  {
+    RefPtr<SyncRunnable> s(new SyncRunnable(aRunnable));
+    s->DispatchToThread(aThread, aForceDispatch);
+  }
+
+protected:
+  NS_IMETHOD Run() override
+  {
+    mRunnable->Run();
+
+    mozilla::MonitorAutoLock lock(mMonitor);
+    MOZ_ASSERT(!mDone);
+
+    mDone = true;
+    mMonitor.Notify();
+
+    return NS_OK;
+  }
+
+private:
+  nsCOMPtr<nsIRunnable> mRunnable;
+  mozilla::Monitor mMonitor;
+  bool mDone;
+};
+
+} // namespace mozilla
+
+#endif // mozilla_SyncRunnable_h
diff --git a/xpcom/threads/TaskDispatcher.h b/xpcom/threads/TaskDispatcher.h
new file mode 100644
index 000000000..405c3acfe
--- /dev/null
+++ b/xpcom/threads/TaskDispatcher.h
@@ -0,0 +1,276 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#if !defined(TaskDispatcher_h_)
+#define TaskDispatcher_h_
+
+#include "mozilla/AbstractThread.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/Unused.h"
+
+#include "nsISupportsImpl.h"
+#include "nsTArray.h"
+#include "nsThreadUtils.h"
+
+#include <queue>
+
+namespace mozilla {
+
+/*
+ * A classic approach to cross-thread communication is to dispatch asynchronous
+ * runnables to perform updates on other threads. This generally works well, but
+ * there are sometimes reasons why we might want to delay the actual dispatch of
+ * these tasks until a specified moment. At present, this is primarily useful to
+ * ensure that mirrored state gets updated atomically - but there may be other
+ * applications as well.
+ *
+ * TaskDispatcher is a general abstract class that accepts tasks and dispatches
+ * them at some later point. These groups of tasks are per-target-thread, and
+ * contain separate queues for several kinds of tasks (see comments  below). - "state change tasks" (which
+ * run first, and are intended to be used to update the value held by mirrors),
+ * and regular tasks, which are other arbitrary operations that the are gated
+ * to run after all the state changes have completed.
+ */
+class TaskDispatcher
+{
+public:
+  TaskDispatcher() {}
+  virtual ~TaskDispatcher() {}
+
+  // Direct tasks are run directly (rather than dispatched asynchronously) when
+  // the tail dispatcher fires. A direct task may cause other tasks to be added
+  // to the tail dispatcher.
+  virtual void AddDirectTask(already_AddRefed<nsIRunnable> aRunnable) = 0;
+
+  // State change tasks are dispatched asynchronously always run before regular
+  // tasks. They are intended to be used to update the value held by mirrors
+  // before any other dispatched tasks are run on the target thread.
+  virtual void AddStateChangeTask(AbstractThread* aThread,
+                                  already_AddRefed<nsIRunnable> aRunnable) = 0;
+
+  // Regular tasks are dispatched asynchronously, and run after state change
+  // tasks.
+  virtual void AddTask(AbstractThread* aThread,
+                       already_AddRefed<nsIRunnable> aRunnable,
+                       AbstractThread::DispatchFailureHandling aFailureHandling = AbstractThread::AssertDispatchSuccess) = 0;
+
+  virtual void DispatchTasksFor(AbstractThread* aThread) = 0;
+  virtual bool HasTasksFor(AbstractThread* aThread) = 0;
+  virtual void DrainDirectTasks() = 0;
+};
+
+/*
+ * AutoTaskDispatcher is a stack-scoped TaskDispatcher implementation that fires
+ * its queued tasks when it is popped off the stack.
+ */
+class AutoTaskDispatcher : public TaskDispatcher
+{
+public:
+  explicit AutoTaskDispatcher(bool aIsTailDispatcher = false)
+    : mIsTailDispatcher(aIsTailDispatcher)
+  {}
+
+  ~AutoTaskDispatcher()
+  {
+    // Given that direct tasks may trigger other code that uses the tail
+    // dispatcher, it's better to avoid processing them in the tail dispatcher's
+    // destructor. So we require TailDispatchers to manually invoke
+    // DrainDirectTasks before the AutoTaskDispatcher gets destroyed. In truth,
+    // this is only necessary in the case where this AutoTaskDispatcher can be
+    // accessed by the direct tasks it dispatches (true for TailDispatchers, but
+    // potentially not true for other hypothetical AutoTaskDispatchers). Feel
+    // free to loosen this restriction to apply only to mIsTailDispatcher if a
+    // use-case requires it.
+    MOZ_ASSERT(!HaveDirectTasks());
+
+    for (size_t i = 0; i < mTaskGroups.Length(); ++i) {
+      DispatchTaskGroup(Move(mTaskGroups[i]));
+    }
+  }
+
+  bool HaveDirectTasks() const
+  {
+    return mDirectTasks.isSome() && !mDirectTasks->empty();
+  }
+
+  void DrainDirectTasks() override
+  {
+    while (HaveDirectTasks()) {
+      nsCOMPtr<nsIRunnable> r = mDirectTasks->front();
+      mDirectTasks->pop();
+      r->Run();
+    }
+  }
+
+  void AddDirectTask(already_AddRefed<nsIRunnable> aRunnable) override
+  {
+    if (mDirectTasks.isNothing()) {
+      mDirectTasks.emplace();
+    }
+    mDirectTasks->push(Move(aRunnable));
+  }
+
+  void AddStateChangeTask(AbstractThread* aThread,
+                          already_AddRefed<nsIRunnable> aRunnable) override
+  {
+    EnsureTaskGroup(aThread).mStateChangeTasks.AppendElement(aRunnable);
+  }
+
+  void AddTask(AbstractThread* aThread,
+               already_AddRefed<nsIRunnable> aRunnable,
+               AbstractThread::DispatchFailureHandling aFailureHandling) override
+  {
+    PerThreadTaskGroup& group = EnsureTaskGroup(aThread);
+    group.mRegularTasks.AppendElement(aRunnable);
+
+    // The task group needs to assert dispatch success if any of the runnables
+    // it's dispatching want to assert it.
+    if (aFailureHandling == AbstractThread::AssertDispatchSuccess) {
+      group.mFailureHandling = AbstractThread::AssertDispatchSuccess;
+    }
+  }
+
+  bool HasTasksFor(AbstractThread* aThread) override
+  {
+    return !!GetTaskGroup(aThread) ||
+           (aThread == AbstractThread::GetCurrent() && HaveDirectTasks());
+  }
+
+  void DispatchTasksFor(AbstractThread* aThread) override
+  {
+    for (size_t i = 0; i < mTaskGroups.Length(); ++i) {
+      if (mTaskGroups[i]->mThread == aThread) {
+        DispatchTaskGroup(Move(mTaskGroups[i]));
+        mTaskGroups.RemoveElementAt(i);
+        return;
+      }
+    }
+  }
+
+private:
+
+  struct PerThreadTaskGroup
+  {
+  public:
+    explicit PerThreadTaskGroup(AbstractThread* aThread)
+      : mThread(aThread), mFailureHandling(AbstractThread::DontAssertDispatchSuccess)
+    {
+      MOZ_COUNT_CTOR(PerThreadTaskGroup);
+    }
+
+    ~PerThreadTaskGroup() { MOZ_COUNT_DTOR(PerThreadTaskGroup); }
+
+    RefPtr<AbstractThread> mThread;
+    nsTArray<nsCOMPtr<nsIRunnable>> mStateChangeTasks;
+    nsTArray<nsCOMPtr<nsIRunnable>> mRegularTasks;
+    AbstractThread::DispatchFailureHandling mFailureHandling;
+  };
+
+  class TaskGroupRunnable : public Runnable
+  {
+    public:
+      explicit TaskGroupRunnable(UniquePtr<PerThreadTaskGroup>&& aTasks) : mTasks(Move(aTasks)) {}
+
+      NS_IMETHOD Run() override
+      {
+        // State change tasks get run all together before any code is run, so
+        // that all state changes are made in an atomic unit.
+        for (size_t i = 0; i < mTasks->mStateChangeTasks.Length(); ++i) {
+          mTasks->mStateChangeTasks[i]->Run();
+        }
+
+        // Once the state changes have completed, drain any direct tasks
+        // generated by those state changes (i.e. watcher notification tasks).
+        // This needs to be outside the loop because we don't want to run code
+        // that might observe intermediate states.
+        MaybeDrainDirectTasks();
+
+        for (size_t i = 0; i < mTasks->mRegularTasks.Length(); ++i) {
+          mTasks->mRegularTasks[i]->Run();
+
+          // Scope direct tasks tightly to the task that generated them.
+          MaybeDrainDirectTasks();
+        }
+
+        return NS_OK;
+      }
+
+    private:
+      void MaybeDrainDirectTasks()
+      {
+        AbstractThread* currentThread = AbstractThread::GetCurrent();
+        if (currentThread) {
+          currentThread->TailDispatcher().DrainDirectTasks();
+        }
+      }
+
+      UniquePtr<PerThreadTaskGroup> mTasks;
+  };
+
+  PerThreadTaskGroup& EnsureTaskGroup(AbstractThread* aThread)
+  {
+    PerThreadTaskGroup* existing = GetTaskGroup(aThread);
+    if (existing) {
+      return *existing;
+    }
+
+    mTaskGroups.AppendElement(new PerThreadTaskGroup(aThread));
+    return *mTaskGroups.LastElement();
+  }
+
+  PerThreadTaskGroup* GetTaskGroup(AbstractThread* aThread)
+  {
+    for (size_t i = 0; i < mTaskGroups.Length(); ++i) {
+      if (mTaskGroups[i]->mThread == aThread) {
+        return mTaskGroups[i].get();
+      }
+    }
+
+    // Not found.
+    return nullptr;
+  }
+
+  void DispatchTaskGroup(UniquePtr<PerThreadTaskGroup> aGroup)
+  {
+    RefPtr<AbstractThread> thread = aGroup->mThread;
+
+    AbstractThread::DispatchFailureHandling failureHandling = aGroup->mFailureHandling;
+    AbstractThread::DispatchReason reason = mIsTailDispatcher ? AbstractThread::TailDispatch
+                                                              : AbstractThread::NormalDispatch;
+    nsCOMPtr<nsIRunnable> r = new TaskGroupRunnable(Move(aGroup));
+    thread->Dispatch(r.forget(), failureHandling, reason);
+  }
+
+  // Direct tasks. We use a Maybe<> because (a) this class is hot, (b)
+  // mDirectTasks often doesn't get anything put into it, and (c) the
+  // std::queue implementation in GNU libstdc++ does two largish heap
+  // allocations when creating a new std::queue.
+  mozilla::Maybe<std::queue<nsCOMPtr<nsIRunnable>>> mDirectTasks;
+
+  // Task groups, organized by thread.
+  nsTArray<UniquePtr<PerThreadTaskGroup>> mTaskGroups;
+
+  // True if this TaskDispatcher represents the tail dispatcher for the thread
+  // upon which it runs.
+  const bool mIsTailDispatcher;
+};
+
+// Little utility class to allow declaring AutoTaskDispatcher as a default
+// parameter for methods that take a TaskDispatcher&.
+template<typename T>
+class PassByRef
+{
+public:
+  PassByRef() {}
+  operator T&() { return mVal; }
+private:
+  T mVal;
+};
+
+} // namespace mozilla
+
+#endif
diff --git a/xpcom/threads/TaskQueue.cpp b/xpcom/threads/TaskQueue.cpp
new file mode 100644
index 000000000..2e593a773
--- /dev/null
+++ b/xpcom/threads/TaskQueue.cpp
@@ -0,0 +1,271 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/TaskQueue.h"
+
+#include "nsIEventTarget.h"
+#include "nsThreadUtils.h"
+
+namespace mozilla {
+
+class TaskQueue::EventTargetWrapper final : public nsIEventTarget
+{
+  RefPtr<TaskQueue> mTaskQueue;
+
+  ~EventTargetWrapper()
+  {
+  }
+
+public:
+  explicit EventTargetWrapper(TaskQueue* aTaskQueue)
+    : mTaskQueue(aTaskQueue)
+  {
+    MOZ_ASSERT(mTaskQueue);
+  }
+
+  NS_IMETHOD
+  DispatchFromScript(nsIRunnable* aEvent, uint32_t aFlags) override
+  {
+    nsCOMPtr<nsIRunnable> ref = aEvent;
+    return Dispatch(ref.forget(), aFlags);
+  }
+
+  NS_IMETHOD
+  Dispatch(already_AddRefed<nsIRunnable> aEvent, uint32_t aFlags) override
+  {
+    nsCOMPtr<nsIRunnable> runnable = aEvent;
+    MonitorAutoLock mon(mTaskQueue->mQueueMonitor);
+    return mTaskQueue->DispatchLocked(/* passed by ref */runnable,
+                                      DontAssertDispatchSuccess,
+                                      NormalDispatch);
+  }
+
+  NS_IMETHOD
+  DelayedDispatch(already_AddRefed<nsIRunnable>, uint32_t aFlags) override
+  {
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  NS_IMETHOD
+  IsOnCurrentThread(bool* aResult) override
+  {
+    *aResult = mTaskQueue->IsCurrentThreadIn();
+    return NS_OK;
+  }
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+};
+
+NS_IMPL_ISUPPORTS(TaskQueue::EventTargetWrapper, nsIEventTarget)
+
+TaskQueue::TaskQueue(already_AddRefed<nsIEventTarget> aTarget,
+                     bool aRequireTailDispatch)
+  : AbstractThread(aRequireTailDispatch)
+  , mTarget(aTarget)
+  , mQueueMonitor("TaskQueue::Queue")
+  , mTailDispatcher(nullptr)
+  , mIsRunning(false)
+  , mIsShutdown(false)
+{
+  MOZ_COUNT_CTOR(TaskQueue);
+}
+
+TaskQueue::~TaskQueue()
+{
+  MonitorAutoLock mon(mQueueMonitor);
+  MOZ_ASSERT(mIsShutdown);
+  MOZ_COUNT_DTOR(TaskQueue);
+}
+
+TaskDispatcher&
+TaskQueue::TailDispatcher()
+{
+  MOZ_ASSERT(IsCurrentThreadIn());
+  MOZ_ASSERT(mTailDispatcher);
+  return *mTailDispatcher;
+}
+
+// Note aRunnable is passed by ref to support conditional ownership transfer.
+// See Dispatch() in TaskQueue.h for more details.
+nsresult
+TaskQueue::DispatchLocked(nsCOMPtr<nsIRunnable>& aRunnable,
+                          DispatchFailureHandling aFailureHandling,
+                          DispatchReason aReason)
+{
+  mQueueMonitor.AssertCurrentThreadOwns();
+  if (mIsShutdown) {
+    return NS_ERROR_FAILURE;
+  }
+
+  AbstractThread* currentThread;
+  if (aReason != TailDispatch && (currentThread = GetCurrent()) && RequiresTailDispatch(currentThread)) {
+    currentThread->TailDispatcher().AddTask(this, aRunnable.forget(), aFailureHandling);
+    return NS_OK;
+  }
+
+  mTasks.push(aRunnable.forget());
+  if (mIsRunning) {
+    return NS_OK;
+  }
+  RefPtr<nsIRunnable> runner(new Runner(this));
+  nsresult rv = mTarget->Dispatch(runner.forget(), NS_DISPATCH_NORMAL);
+  if (NS_FAILED(rv)) {
+    NS_WARNING("Failed to dispatch runnable to run TaskQueue");
+    return rv;
+  }
+  mIsRunning = true;
+
+  return NS_OK;
+}
+
+void
+TaskQueue::AwaitIdle()
+{
+  MonitorAutoLock mon(mQueueMonitor);
+  AwaitIdleLocked();
+}
+
+void
+TaskQueue::AwaitIdleLocked()
+{
+  // Make sure there are no tasks for this queue waiting in the caller's tail
+  // dispatcher.
+  MOZ_ASSERT_IF(AbstractThread::GetCurrent(),
+                !AbstractThread::GetCurrent()->HasTailTasksFor(this));
+
+  mQueueMonitor.AssertCurrentThreadOwns();
+  MOZ_ASSERT(mIsRunning || mTasks.empty());
+  while (mIsRunning) {
+    mQueueMonitor.Wait();
+  }
+}
+
+void
+TaskQueue::AwaitShutdownAndIdle()
+{
+  MOZ_ASSERT(!IsCurrentThreadIn());
+  // Make sure there are no tasks for this queue waiting in the caller's tail
+  // dispatcher.
+  MOZ_ASSERT_IF(AbstractThread::GetCurrent(),
+                !AbstractThread::GetCurrent()->HasTailTasksFor(this));
+
+  MonitorAutoLock mon(mQueueMonitor);
+  while (!mIsShutdown) {
+    mQueueMonitor.Wait();
+  }
+  AwaitIdleLocked();
+}
+
+RefPtr<ShutdownPromise>
+TaskQueue::BeginShutdown()
+{
+  // Dispatch any tasks for this queue waiting in the caller's tail dispatcher,
+  // since this is the last opportunity to do so.
+  if (AbstractThread* currentThread = AbstractThread::GetCurrent()) {
+    currentThread->TailDispatchTasksFor(this);
+  }
+
+  MonitorAutoLock mon(mQueueMonitor);
+  mIsShutdown = true;
+  RefPtr<ShutdownPromise> p = mShutdownPromise.Ensure(__func__);
+  MaybeResolveShutdown();
+  mon.NotifyAll();
+  return p;
+}
+
+bool
+TaskQueue::IsEmpty()
+{
+  MonitorAutoLock mon(mQueueMonitor);
+  return mTasks.empty();
+}
+
+uint32_t
+TaskQueue::ImpreciseLengthForHeuristics()
+{
+  MonitorAutoLock mon(mQueueMonitor);
+  return mTasks.size();
+}
+
+bool
+TaskQueue::IsCurrentThreadIn()
+{
+  bool in = NS_GetCurrentThread() == mRunningThread;
+  return in;
+}
+
+already_AddRefed<nsIEventTarget>
+TaskQueue::WrapAsEventTarget()
+{
+  nsCOMPtr<nsIEventTarget> ref = new EventTargetWrapper(this);
+  return ref.forget();
+}
+
+nsresult
+TaskQueue::Runner::Run()
+{
+  RefPtr<nsIRunnable> event;
+  {
+    MonitorAutoLock mon(mQueue->mQueueMonitor);
+    MOZ_ASSERT(mQueue->mIsRunning);
+    if (mQueue->mTasks.size() == 0) {
+      mQueue->mIsRunning = false;
+      mQueue->MaybeResolveShutdown();
+      mon.NotifyAll();
+      return NS_OK;
+    }
+    event = mQueue->mTasks.front().forget();
+    mQueue->mTasks.pop();
+  }
+  MOZ_ASSERT(event);
+
+  // Note that dropping the queue monitor before running the task, and
+  // taking the monitor again after the task has run ensures we have memory
+  // fences enforced. This means that if the object we're calling wasn't
+  // designed to be threadsafe, it will be, provided we're only calling it
+  // in this task queue.
+  {
+    AutoTaskGuard g(mQueue);
+    event->Run();
+  }
+
+  // Drop the reference to event. The event will hold a reference to the
+  // object it's calling, and we don't want to keep it alive, it may be
+  // making assumptions what holds references to it. This is especially
+  // the case if the object is waiting for us to shutdown, so that it
+  // can shutdown (like in the MediaDecoderStateMachine's SHUTDOWN case).
+  event = nullptr;
+
+  {
+    MonitorAutoLock mon(mQueue->mQueueMonitor);
+    if (mQueue->mTasks.size() == 0) {
+      // No more events to run. Exit the task runner.
+      mQueue->mIsRunning = false;
+      mQueue->MaybeResolveShutdown();
+      mon.NotifyAll();
+      return NS_OK;
+    }
+  }
+
+  // There's at least one more event that we can run. Dispatch this Runner
+  // to the target again to ensure it runs again. Note that we don't just
+  // run in a loop here so that we don't hog the target. This means we may
+  // run on another thread next time, but we rely on the memory fences from
+  // mQueueMonitor for thread safety of non-threadsafe tasks.
+  nsresult rv = mQueue->mTarget->Dispatch(this, NS_DISPATCH_AT_END);
+  if (NS_FAILED(rv)) {
+    // Failed to dispatch, shutdown!
+    MonitorAutoLock mon(mQueue->mQueueMonitor);
+    mQueue->mIsRunning = false;
+    mQueue->mIsShutdown = true;
+    mQueue->MaybeResolveShutdown();
+    mon.NotifyAll();
+  }
+
+  return NS_OK;
+}
+
+} // namespace mozilla
diff --git a/xpcom/threads/TaskQueue.h b/xpcom/threads/TaskQueue.h
new file mode 100644
index 000000000..aafd206a7
--- /dev/null
+++ b/xpcom/threads/TaskQueue.h
@@ -0,0 +1,203 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef TaskQueue_h_
+#define TaskQueue_h_
+
+#include "mozilla/Monitor.h"
+#include "mozilla/MozPromise.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/TaskDispatcher.h"
+#include "mozilla/Unused.h"
+
+#include <queue>
+
+#include "nsThreadUtils.h"
+
+class nsIEventTarget;
+class nsIRunnable;
+
+namespace mozilla {
+
+typedef MozPromise<bool, bool, false> ShutdownPromise;
+
+// Abstracts executing runnables in order on an arbitrary event target. The
+// runnables dispatched to the TaskQueue will be executed in the order in which
+// they're received, and are guaranteed to not be executed concurrently.
+// They may be executed on different threads, and a memory barrier is used
+// to make this threadsafe for objects that aren't already threadsafe.
+//
+// Note, since a TaskQueue can also be converted to an nsIEventTarget using
+// WrapAsEventTarget() its possible to construct a hierarchy of TaskQueues.
+// Consider these three TaskQueues:
+//
+//  TQ1 dispatches to the main thread
+//  TQ2 dispatches to TQ1
+//  TQ3 dispatches to TQ1
+//
+// This ensures there is only ever a single runnable from the entire chain on
+// the main thread.  It also ensures that TQ2 and TQ3 only have a single runnable
+// in TQ1 at any time.
+//
+// This arrangement lets you prioritize work by dispatching runnables directly
+// to TQ1.  You can issue many runnables for important work.  Meanwhile the TQ2
+// and TQ3 work will always execute at most one runnable and then yield.
+class TaskQueue : public AbstractThread
+{
+  class EventTargetWrapper;
+
+public:
+  explicit TaskQueue(already_AddRefed<nsIEventTarget> aTarget,
+                     bool aSupportsTailDispatch = false);
+
+  TaskDispatcher& TailDispatcher() override;
+
+  TaskQueue* AsTaskQueue() override { return this; }
+
+  void Dispatch(already_AddRefed<nsIRunnable> aRunnable,
+                DispatchFailureHandling aFailureHandling = AssertDispatchSuccess,
+                DispatchReason aReason = NormalDispatch) override
+  {
+    nsCOMPtr<nsIRunnable> r = aRunnable;
+    {
+      MonitorAutoLock mon(mQueueMonitor);
+      nsresult rv = DispatchLocked(/* passed by ref */r, aFailureHandling, aReason);
+      MOZ_DIAGNOSTIC_ASSERT(aFailureHandling == DontAssertDispatchSuccess || NS_SUCCEEDED(rv));
+      Unused << rv;
+    }
+    // If the ownership of |r| is not transferred in DispatchLocked() due to
+    // dispatch failure, it will be deleted here outside the lock. We do so
+    // since the destructor of the runnable might access TaskQueue and result
+    // in deadlocks.
+  }
+
+  // Puts the queue in a shutdown state and returns immediately. The queue will
+  // remain alive at least until all the events are drained, because the Runners
+  // hold a strong reference to the task queue, and one of them is always held
+  // by the target event queue when the task queue is non-empty.
+  //
+  // The returned promise is resolved when the queue goes empty.
+  RefPtr<ShutdownPromise> BeginShutdown();
+
+  // Blocks until all task finish executing.
+  void AwaitIdle();
+
+  // Blocks until the queue is flagged for shutdown and all tasks have finished
+  // executing.
+  void AwaitShutdownAndIdle();
+
+  bool IsEmpty();
+  uint32_t ImpreciseLengthForHeuristics();
+
+  // Returns true if the current thread is currently running a Runnable in
+  // the task queue.
+  bool IsCurrentThreadIn() override;
+
+  // Create a new nsIEventTarget wrapper object that dispatches to this
+  // TaskQueue.
+  already_AddRefed<nsIEventTarget> WrapAsEventTarget();
+
+protected:
+  virtual ~TaskQueue();
+
+
+  // Blocks until all task finish executing. Called internally by methods
+  // that need to wait until the task queue is idle.
+  // mQueueMonitor must be held.
+  void AwaitIdleLocked();
+
+  nsresult DispatchLocked(nsCOMPtr<nsIRunnable>& aRunnable,
+                          DispatchFailureHandling aFailureHandling,
+                          DispatchReason aReason = NormalDispatch);
+
+  void MaybeResolveShutdown()
+  {
+    mQueueMonitor.AssertCurrentThreadOwns();
+    if (mIsShutdown && !mIsRunning) {
+      mShutdownPromise.ResolveIfExists(true, __func__);
+      mTarget = nullptr;
+    }
+  }
+
+  nsCOMPtr<nsIEventTarget> mTarget;
+
+  // Monitor that protects the queue and mIsRunning;
+  Monitor mQueueMonitor;
+
+  // Queue of tasks to run.
+  std::queue<nsCOMPtr<nsIRunnable>> mTasks;
+
+  // The thread currently running the task queue. We store a reference
+  // to this so that IsCurrentThreadIn() can tell if the current thread
+  // is the thread currently running in the task queue.
+  //
+  // This may be read on any thread, but may only be written on mRunningThread.
+  // The thread can't die while we're running in it, and we only use it for
+  // pointer-comparison with the current thread anyway - so we make it atomic
+  // and don't refcount it.
+  Atomic<nsIThread*> mRunningThread;
+
+  // RAII class that gets instantiated for each dispatched task.
+  class AutoTaskGuard : public AutoTaskDispatcher
+  {
+  public:
+    explicit AutoTaskGuard(TaskQueue* aQueue)
+      : AutoTaskDispatcher(/* aIsTailDispatcher = */ true), mQueue(aQueue)
+      , mLastCurrentThread(nullptr)
+    {
+      // NB: We don't hold the lock to aQueue here. Don't do anything that
+      // might require it.
+      MOZ_ASSERT(!mQueue->mTailDispatcher);
+      mQueue->mTailDispatcher = this;
+
+      mLastCurrentThread = sCurrentThreadTLS.get();
+      sCurrentThreadTLS.set(aQueue);
+
+      MOZ_ASSERT(mQueue->mRunningThread == nullptr);
+      mQueue->mRunningThread = NS_GetCurrentThread();
+    }
+
+    ~AutoTaskGuard()
+    {
+      DrainDirectTasks();
+
+      MOZ_ASSERT(mQueue->mRunningThread == NS_GetCurrentThread());
+      mQueue->mRunningThread = nullptr;
+
+      sCurrentThreadTLS.set(mLastCurrentThread);
+      mQueue->mTailDispatcher = nullptr;
+    }
+
+  private:
+  TaskQueue* mQueue;
+  AbstractThread* mLastCurrentThread;
+  };
+
+  TaskDispatcher* mTailDispatcher;
+
+  // True if we've dispatched an event to the target to execute events from
+  // the queue.
+  bool mIsRunning;
+
+  // True if we've started our shutdown process.
+  bool mIsShutdown;
+  MozPromiseHolder<ShutdownPromise> mShutdownPromise;
+
+  class Runner : public Runnable {
+  public:
+    explicit Runner(TaskQueue* aQueue)
+      : mQueue(aQueue)
+    {
+    }
+    NS_IMETHOD Run() override;
+  private:
+    RefPtr<TaskQueue> mQueue;
+  };
+};
+
+} // namespace mozilla
+
+#endif // TaskQueue_h_
diff --git a/xpcom/threads/ThreadStackHelper.cpp b/xpcom/threads/ThreadStackHelper.cpp
new file mode 100644
index 000000000..d31bf6359
--- /dev/null
+++ b/xpcom/threads/ThreadStackHelper.cpp
@@ -0,0 +1,726 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ThreadStackHelper.h"
+#include "MainThreadUtils.h"
+#include "nsJSPrincipals.h"
+#include "nsScriptSecurityManager.h"
+#include "jsfriendapi.h"
+#ifdef MOZ_THREADSTACKHELPER_NATIVE
+#include "shared-libraries.h"
+#endif
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/IntegerPrintfMacros.h"
+#include "mozilla/Move.h"
+#include "mozilla/Scoped.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/MemoryChecking.h"
+#include "mozilla/Sprintf.h"
+
+#ifdef __GNUC__
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wshadow"
+#endif
+
+#if defined(MOZ_VALGRIND)
+# include <valgrind/valgrind.h>
+#endif
+
+#include <string.h>
+#include <vector>
+#include <cstdlib>
+
+#ifdef XP_LINUX
+#include <ucontext.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#endif
+
+#ifdef __GNUC__
+# pragma GCC diagnostic pop // -Wshadow
+#endif
+
+#if defined(XP_LINUX) || defined(XP_MACOSX)
+#include <pthread.h>
+#endif
+
+#ifdef ANDROID
+#ifndef SYS_gettid
+#define SYS_gettid __NR_gettid
+#endif
+#if defined(__arm__) && !defined(__NR_rt_tgsigqueueinfo)
+// Some NDKs don't define this constant even though the kernel supports it.
+#define __NR_rt_tgsigqueueinfo (__NR_SYSCALL_BASE+363)
+#endif
+#ifndef SYS_rt_tgsigqueueinfo
+#define SYS_rt_tgsigqueueinfo __NR_rt_tgsigqueueinfo
+#endif
+#endif
+
+#ifdef MOZ_THREADSTACKHELPER_NATIVE
+#if defined(MOZ_THREADSTACKHELPER_X86) || \
+    defined(MOZ_THREADSTACKHELPER_X64) || \
+    defined(MOZ_THREADSTACKHELPER_ARM)
+// On these architectures, the stack grows downwards (toward lower addresses).
+#define MOZ_THREADSTACKHELPER_STACK_GROWS_DOWN
+#else
+#error "Unsupported architecture"
+#endif
+#endif // MOZ_THREADSTACKHELPER_NATIVE
+
+namespace mozilla {
+
+void
+ThreadStackHelper::Startup()
+{
+#if defined(XP_LINUX)
+  MOZ_ASSERT(NS_IsMainThread());
+  if (!sInitialized) {
+    // TODO: centralize signal number allocation
+    sFillStackSignum = SIGRTMIN + 4;
+    if (sFillStackSignum > SIGRTMAX) {
+      // Leave uninitialized
+      MOZ_ASSERT(false);
+      return;
+    }
+    struct sigaction sigact = {};
+    sigact.sa_sigaction = FillStackHandler;
+    sigemptyset(&sigact.sa_mask);
+    sigact.sa_flags = SA_SIGINFO | SA_RESTART;
+    MOZ_ALWAYS_TRUE(!::sigaction(sFillStackSignum, &sigact, nullptr));
+  }
+  sInitialized++;
+#endif
+}
+
+void
+ThreadStackHelper::Shutdown()
+{
+#if defined(XP_LINUX)
+  MOZ_ASSERT(NS_IsMainThread());
+  if (sInitialized == 1) {
+    struct sigaction sigact = {};
+    sigact.sa_handler = SIG_DFL;
+    MOZ_ALWAYS_TRUE(!::sigaction(sFillStackSignum, &sigact, nullptr));
+  }
+  sInitialized--;
+#endif
+}
+
+ThreadStackHelper::ThreadStackHelper()
+  : mStackToFill(nullptr)
+#ifdef MOZ_THREADSTACKHELPER_PSEUDO
+  , mPseudoStack(mozilla_get_pseudo_stack())
+#ifdef MOZ_THREADSTACKHELPER_NATIVE
+  , mContextToFill(nullptr)
+#endif
+  , mMaxStackSize(Stack::sMaxInlineStorage)
+  , mMaxBufferSize(512)
+#endif
+{
+#if defined(XP_LINUX)
+  MOZ_ALWAYS_TRUE(!::sem_init(&mSem, 0, 0));
+  mThreadID = ::syscall(SYS_gettid);
+#elif defined(XP_WIN)
+  mInitialized = !!::DuplicateHandle(
+    ::GetCurrentProcess(), ::GetCurrentThread(),
+    ::GetCurrentProcess(), &mThreadID,
+    THREAD_SUSPEND_RESUME
+#ifdef MOZ_THREADSTACKHELPER_NATIVE
+    | THREAD_GET_CONTEXT | THREAD_QUERY_INFORMATION
+#endif
+    , FALSE, 0);
+  MOZ_ASSERT(mInitialized);
+#elif defined(XP_MACOSX)
+  mThreadID = mach_thread_self();
+#endif
+
+#ifdef MOZ_THREADSTACKHELPER_NATIVE
+  GetThreadStackBase();
+#endif
+}
+
+ThreadStackHelper::~ThreadStackHelper()
+{
+#if defined(XP_LINUX)
+  MOZ_ALWAYS_TRUE(!::sem_destroy(&mSem));
+#elif defined(XP_WIN)
+  if (mInitialized) {
+    MOZ_ALWAYS_TRUE(!!::CloseHandle(mThreadID));
+  }
+#endif
+}
+
+#ifdef MOZ_THREADSTACKHELPER_NATIVE
+void ThreadStackHelper::GetThreadStackBase()
+{
+  mThreadStackBase = 0;
+
+#if defined(XP_LINUX)
+  void* stackAddr;
+  size_t stackSize;
+  ::pthread_t pthr = ::pthread_self();
+  ::pthread_attr_t pthr_attr;
+  NS_ENSURE_TRUE_VOID(!::pthread_getattr_np(pthr, &pthr_attr));
+  if (!::pthread_attr_getstack(&pthr_attr, &stackAddr, &stackSize)) {
+#ifdef MOZ_THREADSTACKHELPER_STACK_GROWS_DOWN
+    mThreadStackBase = intptr_t(stackAddr) + stackSize;
+#else
+    mThreadStackBase = intptr_t(stackAddr);
+#endif
+  }
+  MOZ_ALWAYS_TRUE(!::pthread_attr_destroy(&pthr_attr));
+
+#elif defined(XP_WIN)
+  ::MEMORY_BASIC_INFORMATION meminfo = {};
+  NS_ENSURE_TRUE_VOID(::VirtualQuery(&meminfo, &meminfo, sizeof(meminfo)));
+#ifdef MOZ_THREADSTACKHELPER_STACK_GROWS_DOWN
+  mThreadStackBase = intptr_t(meminfo.BaseAddress) + meminfo.RegionSize;
+#else
+  mThreadStackBase = intptr_t(meminfo.AllocationBase);
+#endif
+
+#elif defined(XP_MACOSX)
+  ::pthread_t pthr = ::pthread_self();
+  mThreadStackBase = intptr_t(::pthread_get_stackaddr_np(pthr));
+
+#else
+  #error "Unsupported platform"
+#endif // platform
+}
+#endif // MOZ_THREADSTACKHELPER_NATIVE
+
+namespace {
+template<typename T>
+class ScopedSetPtr
+{
+private:
+  T*& mPtr;
+public:
+  ScopedSetPtr(T*& p, T* val) : mPtr(p) { mPtr = val; }
+  ~ScopedSetPtr() { mPtr = nullptr; }
+};
+} // namespace
+
+void
+ThreadStackHelper::GetStack(Stack& aStack)
+{
+  // Always run PrepareStackBuffer first to clear aStack
+  if (!PrepareStackBuffer(aStack)) {
+    // Skip and return empty aStack
+    return;
+  }
+
+  ScopedSetPtr<Stack> stackPtr(mStackToFill, &aStack);
+
+#if defined(XP_LINUX)
+  if (!sInitialized) {
+    MOZ_ASSERT(false);
+    return;
+  }
+  siginfo_t uinfo = {};
+  uinfo.si_signo = sFillStackSignum;
+  uinfo.si_code = SI_QUEUE;
+  uinfo.si_pid = getpid();
+  uinfo.si_uid = getuid();
+  uinfo.si_value.sival_ptr = this;
+  if (::syscall(SYS_rt_tgsigqueueinfo, uinfo.si_pid,
+                mThreadID, sFillStackSignum, &uinfo)) {
+    // rt_tgsigqueueinfo was added in Linux 2.6.31.
+    // Could have failed because the syscall did not exist.
+    return;
+  }
+  MOZ_ALWAYS_TRUE(!::sem_wait(&mSem));
+
+#elif defined(XP_WIN)
+  if (!mInitialized) {
+    MOZ_ASSERT(false);
+    return;
+  }
+  if (::SuspendThread(mThreadID) == DWORD(-1)) {
+    MOZ_ASSERT(false);
+    return;
+  }
+
+  // SuspendThread is asynchronous, so the thread may still be running. Use
+  // GetThreadContext to ensure it's really suspended.
+  // See https://blogs.msdn.microsoft.com/oldnewthing/20150205-00/?p=44743.
+  CONTEXT context;
+  context.ContextFlags = CONTEXT_CONTROL;
+  if (::GetThreadContext(mThreadID, &context)) {
+    FillStackBuffer();
+    FillThreadContext();
+  }
+
+  MOZ_ALWAYS_TRUE(::ResumeThread(mThreadID) != DWORD(-1));
+
+#elif defined(XP_MACOSX)
+# if defined(MOZ_VALGRIND) && defined(RUNNING_ON_VALGRIND)
+  if (RUNNING_ON_VALGRIND) {
+    /* thread_suspend and thread_resume sometimes hang runs on Valgrind,
+       for unknown reasons.  So, just avoid them.  See bug 1100911. */
+    return;
+  }
+# endif
+
+  if (::thread_suspend(mThreadID) != KERN_SUCCESS) {
+    MOZ_ASSERT(false);
+    return;
+  }
+
+  FillStackBuffer();
+  FillThreadContext();
+
+  MOZ_ALWAYS_TRUE(::thread_resume(mThreadID) == KERN_SUCCESS);
+
+#endif
+}
+
+#ifdef MOZ_THREADSTACKHELPER_NATIVE
+class ThreadStackHelper::ThreadContext final
+{
+public:
+  // TODO: provide per-platform definition of Context.
+  typedef struct {} Context;
+
+  // Limit copied stack to 4kB
+  static const size_t kMaxStackSize = 0x1000;
+  // Limit unwound stack to 32 frames
+  static const unsigned int kMaxStackFrames = 32;
+  // Whether this structure contains valid data
+  bool mValid;
+  // Processor context
+  Context mContext;
+  // Stack area
+  UniquePtr<uint8_t[]> mStack;
+  // Start of stack area
+  uintptr_t mStackBase;
+  // Size of stack area
+  size_t mStackSize;
+  // End of stack area
+  const void* mStackEnd;
+
+  ThreadContext()
+    : mValid(false)
+    , mStackBase(0)
+    , mStackSize(0)
+    , mStackEnd(nullptr) {}
+};
+#endif // MOZ_THREADSTACKHELPER_NATIVE
+
+void
+ThreadStackHelper::GetNativeStack(Stack& aStack)
+{
+#ifdef MOZ_THREADSTACKHELPER_NATIVE
+  ThreadContext context;
+  context.mStack = MakeUnique<uint8_t[]>(ThreadContext::kMaxStackSize);
+
+  ScopedSetPtr<ThreadContext> contextPtr(mContextToFill, &context);
+
+  // Get pseudostack first and fill the thread context.
+  GetStack(aStack);
+  NS_ENSURE_TRUE_VOID(context.mValid);
+
+  // TODO: walk the saved stack frames.
+#endif // MOZ_THREADSTACKHELPER_NATIVE
+}
+
+#ifdef XP_LINUX
+
+int ThreadStackHelper::sInitialized;
+int ThreadStackHelper::sFillStackSignum;
+
+void
+ThreadStackHelper::FillStackHandler(int aSignal, siginfo_t* aInfo,
+                                    void* aContext)
+{
+  ThreadStackHelper* const helper =
+    reinterpret_cast<ThreadStackHelper*>(aInfo->si_value.sival_ptr);
+  helper->FillStackBuffer();
+  helper->FillThreadContext(aContext);
+  ::sem_post(&helper->mSem);
+}
+
+#endif // XP_LINUX
+
+bool
+ThreadStackHelper::PrepareStackBuffer(Stack& aStack)
+{
+  // Return false to skip getting the stack and return an empty stack
+  aStack.clear();
+#ifdef MOZ_THREADSTACKHELPER_PSEUDO
+  /* Normally, provided the profiler is enabled, it would be an error if we
+     don't have a pseudostack here (the thread probably forgot to call
+     profiler_register_thread). However, on B2G, profiling secondary threads
+     may be disabled despite profiler being enabled. This is by-design and
+     is not an error. */
+#ifdef MOZ_WIDGET_GONK
+  if (!mPseudoStack) {
+    return false;
+  }
+#endif
+  MOZ_ASSERT(mPseudoStack);
+  if (!aStack.reserve(mMaxStackSize) ||
+      !aStack.reserve(aStack.capacity()) || // reserve up to the capacity
+      !aStack.EnsureBufferCapacity(mMaxBufferSize)) {
+    return false;
+  }
+  return true;
+#else
+  return false;
+#endif
+}
+
+#ifdef MOZ_THREADSTACKHELPER_PSEUDO
+
+namespace {
+
+bool
+IsChromeJSScript(JSScript* aScript)
+{
+  // May be called from another thread or inside a signal handler.
+  // We assume querying the script is safe but we must not manipulate it.
+
+  nsIScriptSecurityManager* const secman =
+    nsScriptSecurityManager::GetScriptSecurityManager();
+  NS_ENSURE_TRUE(secman, false);
+
+  JSPrincipals* const principals = JS_GetScriptPrincipals(aScript);
+  return secman->IsSystemPrincipal(nsJSPrincipals::get(principals));
+}
+
+// Get the full path after the URI scheme, if the URI matches the scheme.
+// For example, GetFullPathForScheme("a://b/c/d/e", "a://") returns "b/c/d/e".
+template <size_t LEN>
+const char*
+GetFullPathForScheme(const char* filename, const char (&scheme)[LEN]) {
+  // Account for the null terminator included in LEN.
+  if (!strncmp(filename, scheme, LEN - 1)) {
+    return filename + LEN - 1;
+  }
+  return nullptr;
+}
+
+// Get the full path after a URI component, if the URI contains the component.
+// For example, GetPathAfterComponent("a://b/c/d/e", "/c/") returns "d/e".
+template <size_t LEN>
+const char*
+GetPathAfterComponent(const char* filename, const char (&component)[LEN]) {
+  const char* found = nullptr;
+  const char* next = strstr(filename, component);
+  while (next) {
+    // Move 'found' to end of the component, after the separator '/'.
+    // 'LEN - 1' accounts for the null terminator included in LEN,
+    found = next + LEN - 1;
+    // Resume searching before the separator '/'.
+    next = strstr(found - 1, component);
+  }
+  return found;
+}
+
+} // namespace
+
+const char*
+ThreadStackHelper::AppendJSEntry(const volatile StackEntry* aEntry,
+                                 intptr_t& aAvailableBufferSize,
+                                 const char* aPrevLabel)
+{
+  // May be called from another thread or inside a signal handler.
+  // We assume querying the script is safe but we must not manupulate it.
+  // Also we must not allocate any memory from heap.
+  MOZ_ASSERT(aEntry->isJs());
+
+  const char* label;
+  JSScript* script = aEntry->script();
+  if (!script) {
+    label = "(profiling suppressed)";
+  } else if (IsChromeJSScript(aEntry->script())) {
+    const char* filename = JS_GetScriptFilename(aEntry->script());
+    const unsigned lineno = JS_PCToLineNumber(aEntry->script(), aEntry->pc());
+    MOZ_ASSERT(filename);
+
+    char buffer[128]; // Enough to fit longest js file name from the tree
+
+    // Some script names are in the form "foo -> bar -> baz".
+    // Here we find the origin of these redirected scripts.
+    const char* basename = GetPathAfterComponent(filename, " -> ");
+    if (basename) {
+      filename = basename;
+    }
+
+    basename = GetFullPathForScheme(filename, "chrome://");
+    if (!basename) {
+      basename = GetFullPathForScheme(filename, "resource://");
+    }
+    if (!basename) {
+      // If the (add-on) script is located under the {profile}/extensions
+      // directory, extract the path after the /extensions/ part.
+      basename = GetPathAfterComponent(filename, "/extensions/");
+    }
+    if (!basename) {
+      // Only keep the file base name for paths outside the above formats.
+      basename = strrchr(filename, '/');
+      basename = basename ? basename + 1 : filename;
+      // Look for Windows path separator as well.
+      filename = strrchr(basename, '\\');
+      if (filename) {
+        basename = filename + 1;
+      }
+    }
+
+    size_t len = SprintfLiteral(buffer, "%s:%u", basename, lineno);
+    if (len < sizeof(buffer)) {
+      if (mStackToFill->IsSameAsEntry(aPrevLabel, buffer)) {
+        return aPrevLabel;
+      }
+
+      // Keep track of the required buffer size
+      aAvailableBufferSize -= (len + 1);
+      if (aAvailableBufferSize >= 0) {
+        // Buffer is big enough.
+        return mStackToFill->InfallibleAppendViaBuffer(buffer, len);
+      }
+      // Buffer is not big enough; fall through to using static label below.
+    }
+    // snprintf failed or buffer is not big enough.
+    label = "(chrome script)";
+  } else {
+    label = "(content script)";
+  }
+
+  if (mStackToFill->IsSameAsEntry(aPrevLabel, label)) {
+    return aPrevLabel;
+  }
+  mStackToFill->infallibleAppend(label);
+  return label;
+}
+
+#endif // MOZ_THREADSTACKHELPER_PSEUDO
+
+void
+ThreadStackHelper::FillStackBuffer()
+{
+  MOZ_ASSERT(mStackToFill->empty());
+
+#ifdef MOZ_THREADSTACKHELPER_PSEUDO
+  size_t reservedSize = mStackToFill->capacity();
+  size_t reservedBufferSize = mStackToFill->AvailableBufferSize();
+  intptr_t availableBufferSize = intptr_t(reservedBufferSize);
+
+  // Go from front to back
+  const volatile StackEntry* entry = mPseudoStack->mStack;
+  const volatile StackEntry* end = entry + mPseudoStack->stackSize();
+  // Deduplicate identical, consecutive frames
+  const char* prevLabel = nullptr;
+  for (; reservedSize-- && entry != end; entry++) {
+    /* We only accept non-copy labels, including js::RunScript,
+       because we only want static labels in the hang stack. */
+    if (entry->isCopyLabel()) {
+      continue;
+    }
+    if (entry->isJs()) {
+      prevLabel = AppendJSEntry(entry, availableBufferSize, prevLabel);
+      continue;
+    }
+#ifdef MOZ_THREADSTACKHELPER_NATIVE
+    if (mContextToFill) {
+      mContextToFill->mStackEnd = entry->stackAddress();
+    }
+#endif
+    const char* const label = entry->label();
+    if (mStackToFill->IsSameAsEntry(prevLabel, label)) {
+      // Avoid duplicate labels to save space in the stack.
+      continue;
+    }
+    mStackToFill->infallibleAppend(label);
+    prevLabel = label;
+  }
+
+  // end != entry if we exited early due to not enough reserved frames.
+  // Expand the number of reserved frames for next time.
+  mMaxStackSize = mStackToFill->capacity() + (end - entry);
+
+  // availableBufferSize < 0 if we needed a larger buffer than we reserved.
+  // Calculate a new reserve size for next time.
+  if (availableBufferSize < 0) {
+    mMaxBufferSize = reservedBufferSize - availableBufferSize;
+  }
+#endif
+}
+
+MOZ_ASAN_BLACKLIST void
+ThreadStackHelper::FillThreadContext(void* aContext)
+{
+#ifdef MOZ_THREADSTACKHELPER_NATIVE
+  if (!mContextToFill) {
+    return;
+  }
+
+#if 0 // TODO: remove dependency on Breakpad structs.
+#if defined(XP_LINUX)
+  const ucontext_t& context = *reinterpret_cast<ucontext_t*>(aContext);
+#if defined(MOZ_THREADSTACKHELPER_X86)
+  mContextToFill->mContext.context_flags = MD_CONTEXT_X86_FULL;
+  mContextToFill->mContext.edi = context.uc_mcontext.gregs[REG_EDI];
+  mContextToFill->mContext.esi = context.uc_mcontext.gregs[REG_ESI];
+  mContextToFill->mContext.ebx = context.uc_mcontext.gregs[REG_EBX];
+  mContextToFill->mContext.edx = context.uc_mcontext.gregs[REG_EDX];
+  mContextToFill->mContext.ecx = context.uc_mcontext.gregs[REG_ECX];
+  mContextToFill->mContext.eax = context.uc_mcontext.gregs[REG_EAX];
+  mContextToFill->mContext.ebp = context.uc_mcontext.gregs[REG_EBP];
+  mContextToFill->mContext.eip = context.uc_mcontext.gregs[REG_EIP];
+  mContextToFill->mContext.eflags = context.uc_mcontext.gregs[REG_EFL];
+  mContextToFill->mContext.esp = context.uc_mcontext.gregs[REG_ESP];
+#elif defined(MOZ_THREADSTACKHELPER_X64)
+  mContextToFill->mContext.context_flags = MD_CONTEXT_AMD64_FULL;
+  mContextToFill->mContext.eflags = uint32_t(context.uc_mcontext.gregs[REG_EFL]);
+  mContextToFill->mContext.rax = context.uc_mcontext.gregs[REG_RAX];
+  mContextToFill->mContext.rcx = context.uc_mcontext.gregs[REG_RCX];
+  mContextToFill->mContext.rdx = context.uc_mcontext.gregs[REG_RDX];
+  mContextToFill->mContext.rbx = context.uc_mcontext.gregs[REG_RBX];
+  mContextToFill->mContext.rsp = context.uc_mcontext.gregs[REG_RSP];
+  mContextToFill->mContext.rbp = context.uc_mcontext.gregs[REG_RBP];
+  mContextToFill->mContext.rsi = context.uc_mcontext.gregs[REG_RSI];
+  mContextToFill->mContext.rdi = context.uc_mcontext.gregs[REG_RDI];
+  memcpy(&mContextToFill->mContext.r8,
+         &context.uc_mcontext.gregs[REG_R8], 8 * sizeof(int64_t));
+  mContextToFill->mContext.rip = context.uc_mcontext.gregs[REG_RIP];
+#elif defined(MOZ_THREADSTACKHELPER_ARM)
+  mContextToFill->mContext.context_flags = MD_CONTEXT_ARM_FULL;
+  memcpy(&mContextToFill->mContext.iregs[0],
+         &context.uc_mcontext.arm_r0, 17 * sizeof(int32_t));
+#else
+  #error "Unsupported architecture"
+#endif // architecture
+
+#elif defined(XP_WIN)
+  // Breakpad context struct is based off of the Windows CONTEXT struct,
+  // so we assume they are the same; do some sanity checks to make sure.
+  static_assert(sizeof(ThreadContext::Context) == sizeof(::CONTEXT),
+                "Context struct mismatch");
+  static_assert(offsetof(ThreadContext::Context, context_flags) ==
+                offsetof(::CONTEXT, ContextFlags),
+                "Context struct mismatch");
+  mContextToFill->mContext.context_flags = CONTEXT_FULL;
+  NS_ENSURE_TRUE_VOID(::GetThreadContext(mThreadID,
+      reinterpret_cast<::CONTEXT*>(&mContextToFill->mContext)));
+
+#elif defined(XP_MACOSX)
+#if defined(MOZ_THREADSTACKHELPER_X86)
+  const thread_state_flavor_t flavor = x86_THREAD_STATE32;
+  x86_thread_state32_t state = {};
+  mach_msg_type_number_t count = x86_THREAD_STATE32_COUNT;
+#elif defined(MOZ_THREADSTACKHELPER_X64)
+  const thread_state_flavor_t flavor = x86_THREAD_STATE64;
+  x86_thread_state64_t state = {};
+  mach_msg_type_number_t count = x86_THREAD_STATE64_COUNT;
+#elif defined(MOZ_THREADSTACKHELPER_ARM)
+  const thread_state_flavor_t flavor = ARM_THREAD_STATE;
+  arm_thread_state_t state = {};
+  mach_msg_type_number_t count = ARM_THREAD_STATE_COUNT;
+#endif
+  NS_ENSURE_TRUE_VOID(KERN_SUCCESS == ::thread_get_state(
+    mThreadID, flavor, reinterpret_cast<thread_state_t>(&state), &count));
+#if __DARWIN_UNIX03
+#define GET_REGISTER(s, r) ((s).__##r)
+#else
+#define GET_REGISTER(s, r) ((s).r)
+#endif
+#if defined(MOZ_THREADSTACKHELPER_X86)
+  mContextToFill->mContext.context_flags = MD_CONTEXT_X86_FULL;
+  mContextToFill->mContext.edi = GET_REGISTER(state, edi);
+  mContextToFill->mContext.esi = GET_REGISTER(state, esi);
+  mContextToFill->mContext.ebx = GET_REGISTER(state, ebx);
+  mContextToFill->mContext.edx = GET_REGISTER(state, edx);
+  mContextToFill->mContext.ecx = GET_REGISTER(state, ecx);
+  mContextToFill->mContext.eax = GET_REGISTER(state, eax);
+  mContextToFill->mContext.ebp = GET_REGISTER(state, ebp);
+  mContextToFill->mContext.eip = GET_REGISTER(state, eip);
+  mContextToFill->mContext.eflags = GET_REGISTER(state, eflags);
+  mContextToFill->mContext.esp = GET_REGISTER(state, esp);
+#elif defined(MOZ_THREADSTACKHELPER_X64)
+  mContextToFill->mContext.context_flags = MD_CONTEXT_AMD64_FULL;
+  mContextToFill->mContext.eflags = uint32_t(GET_REGISTER(state, rflags));
+  mContextToFill->mContext.rax = GET_REGISTER(state, rax);
+  mContextToFill->mContext.rcx = GET_REGISTER(state, rcx);
+  mContextToFill->mContext.rdx = GET_REGISTER(state, rdx);
+  mContextToFill->mContext.rbx = GET_REGISTER(state, rbx);
+  mContextToFill->mContext.rsp = GET_REGISTER(state, rsp);
+  mContextToFill->mContext.rbp = GET_REGISTER(state, rbp);
+  mContextToFill->mContext.rsi = GET_REGISTER(state, rsi);
+  mContextToFill->mContext.rdi = GET_REGISTER(state, rdi);
+  memcpy(&mContextToFill->mContext.r8,
+         &GET_REGISTER(state, r8), 8 * sizeof(int64_t));
+  mContextToFill->mContext.rip = GET_REGISTER(state, rip);
+#elif defined(MOZ_THREADSTACKHELPER_ARM)
+  mContextToFill->mContext.context_flags = MD_CONTEXT_ARM_FULL;
+  memcpy(mContextToFill->mContext.iregs,
+         GET_REGISTER(state, r), 17 * sizeof(int32_t));
+#else
+  #error "Unsupported architecture"
+#endif // architecture
+#undef GET_REGISTER
+
+#else
+  #error "Unsupported platform"
+#endif // platform
+
+  intptr_t sp = 0;
+#if defined(MOZ_THREADSTACKHELPER_X86)
+  sp = mContextToFill->mContext.esp;
+#elif defined(MOZ_THREADSTACKHELPER_X64)
+  sp = mContextToFill->mContext.rsp;
+#elif defined(MOZ_THREADSTACKHELPER_ARM)
+  sp = mContextToFill->mContext.iregs[13];
+#else
+  #error "Unsupported architecture"
+#endif // architecture
+  NS_ENSURE_TRUE_VOID(sp);
+  NS_ENSURE_TRUE_VOID(mThreadStackBase);
+
+  size_t stackSize = std::min(intptr_t(ThreadContext::kMaxStackSize),
+                              std::abs(sp - mThreadStackBase));
+
+  if (mContextToFill->mStackEnd) {
+    // Limit the start of stack to a certain location if specified.
+    stackSize = std::min(intptr_t(stackSize),
+      std::abs(sp - intptr_t(mContextToFill->mStackEnd)));
+  }
+
+#ifndef MOZ_THREADSTACKHELPER_STACK_GROWS_DOWN
+  // If if the stack grows upwards, and we need to recalculate our
+  // stack copy's base address. Subtract sizeof(void*) so that the
+  // location pointed to by sp is included.
+  sp -= stackSize - sizeof(void*);
+#endif
+
+#ifndef MOZ_ASAN
+  memcpy(mContextToFill->mStack.get(), reinterpret_cast<void*>(sp), stackSize);
+  // Valgrind doesn't care about the access outside the stack frame, but
+  // the presence of uninitialised values on the stack does cause it to
+  // later report a lot of false errors when Breakpad comes to unwind it.
+  // So mark the extracted data as defined.
+  MOZ_MAKE_MEM_DEFINED(mContextToFill->mStack.get(), stackSize);
+#else
+  // ASan will flag memcpy for access outside of stack frames,
+  // so roll our own memcpy here.
+  intptr_t* dst = reinterpret_cast<intptr_t*>(&mContextToFill->mStack[0]);
+  const intptr_t* src = reinterpret_cast<intptr_t*>(sp);
+  for (intptr_t len = stackSize; len > 0; len -= sizeof(*src)) {
+    *(dst++) = *(src++);
+  }
+#endif
+
+  mContextToFill->mStackBase = uintptr_t(sp);
+  mContextToFill->mStackSize = stackSize;
+  mContextToFill->mValid = true;
+#endif
+#endif // MOZ_THREADSTACKHELPER_NATIVE
+}
+
+} // namespace mozilla
diff --git a/xpcom/threads/ThreadStackHelper.h b/xpcom/threads/ThreadStackHelper.h
new file mode 100644
index 000000000..9c40ad5e2
--- /dev/null
+++ b/xpcom/threads/ThreadStackHelper.h
@@ -0,0 +1,147 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_ThreadStackHelper_h
+#define mozilla_ThreadStackHelper_h
+
+#include "mozilla/ThreadHangStats.h"
+
+#include "GeckoProfiler.h"
+
+#include <stddef.h>
+
+#if defined(XP_LINUX)
+#include <signal.h>
+#include <semaphore.h>
+#include <sys/types.h>
+#elif defined(XP_WIN)
+#include <windows.h>
+#elif defined(XP_MACOSX)
+#include <mach/mach.h>
+#endif
+
+// Support pseudostack on these platforms.
+#if defined(XP_LINUX) || defined(XP_WIN) || defined(XP_MACOSX)
+#  ifdef MOZ_ENABLE_PROFILER_SPS
+#    define MOZ_THREADSTACKHELPER_PSEUDO
+#  endif
+#endif
+
+#ifdef MOZ_THREADSTACKHELPER_PSEUDO
+#  define MOZ_THREADSTACKHELPER_NATIVE
+#  if defined(__i386__) || defined(_M_IX86)
+#    define MOZ_THREADSTACKHELPER_X86
+#  elif defined(__x86_64__) || defined(_M_X64)
+#    define MOZ_THREADSTACKHELPER_X64
+#  elif defined(__arm__) || defined(_M_ARM)
+#    define MOZ_THREADSTACKHELPER_ARM
+#  else
+     // Unsupported architecture
+#    undef MOZ_THREADSTACKHELPER_NATIVE
+#  endif
+#endif
+
+namespace mozilla {
+
+/**
+ * ThreadStackHelper is used to retrieve the profiler pseudo-stack of a
+ * thread, as an alternative of using the profiler to take a profile.
+ * The target thread first declares an ThreadStackHelper instance;
+ * then another thread can call ThreadStackHelper::GetStack to retrieve
+ * the pseudo-stack of the target thread at that instant.
+ *
+ * Only non-copying labels are included in the stack, which means labels
+ * with custom text and markers are not included.
+ */
+class ThreadStackHelper
+{
+public:
+  typedef Telemetry::HangStack Stack;
+
+private:
+  Stack* mStackToFill;
+#ifdef MOZ_THREADSTACKHELPER_PSEUDO
+  const PseudoStack* const mPseudoStack;
+#ifdef MOZ_THREADSTACKHELPER_NATIVE
+  class ThreadContext;
+  // Set to non-null if GetStack should get the thread context.
+  ThreadContext* mContextToFill;
+  intptr_t mThreadStackBase;
+#endif
+  size_t mMaxStackSize;
+  size_t mMaxBufferSize;
+#endif
+
+  bool PrepareStackBuffer(Stack& aStack);
+  void FillStackBuffer();
+  void FillThreadContext(void* aContext = nullptr);
+#ifdef MOZ_THREADSTACKHELPER_PSEUDO
+  const char* AppendJSEntry(const volatile StackEntry* aEntry,
+                            intptr_t& aAvailableBufferSize,
+                            const char* aPrevLabel);
+#endif
+#ifdef MOZ_THREADSTACKHELPER_NATIVE
+  void GetThreadStackBase();
+#endif
+
+public:
+  /**
+   * Initialize ThreadStackHelper. Must be called from main thread.
+   */
+  static void Startup();
+  /**
+   * Uninitialize ThreadStackHelper. Must be called from main thread.
+   */
+  static void Shutdown();
+
+  /**
+   * Create a ThreadStackHelper instance targeting the current thread.
+   */
+  ThreadStackHelper();
+
+  ~ThreadStackHelper();
+
+  /**
+   * Retrieve the current pseudostack of the thread associated
+   * with this ThreadStackHelper.
+   *
+   * @param aStack Stack instance to be filled.
+   */
+  void GetStack(Stack& aStack);
+
+  /**
+   * Retrieve the current native stack of the thread associated
+   * with this ThreadStackHelper.
+   *
+   * @param aNativeStack Stack instance to be filled.
+   */
+  void GetNativeStack(Stack& aStack);
+
+#if defined(XP_LINUX)
+private:
+  static int sInitialized;
+  static int sFillStackSignum;
+
+  static void FillStackHandler(int aSignal, siginfo_t* aInfo, void* aContext);
+
+  sem_t mSem;
+  pid_t mThreadID;
+
+#elif defined(XP_WIN)
+private:
+  bool mInitialized;
+  HANDLE mThreadID;
+
+#elif defined(XP_MACOSX)
+private:
+  thread_act_t mThreadID;
+
+#endif
+};
+
+} // namespace mozilla
+
+#endif // mozilla_ThreadStackHelper_h
diff --git a/xpcom/threads/ThrottledEventQueue.cpp b/xpcom/threads/ThrottledEventQueue.cpp
new file mode 100644
index 000000000..941566ef2
--- /dev/null
+++ b/xpcom/threads/ThrottledEventQueue.cpp
@@ -0,0 +1,446 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ThrottledEventQueue.h"
+
+#include "mozilla/Atomics.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/Unused.h"
+#include "nsEventQueue.h"
+
+namespace mozilla {
+
+using mozilla::services::GetObserverService;
+
+namespace {
+
+static const char kShutdownTopic[] = "xpcom-shutdown";
+
+} // anonymous namespace
+
+// The ThrottledEventQueue is designed with inner and outer objects:
+//
+//       XPCOM code    nsObserverService
+//            |               |
+//            |               |
+//            v               |
+//        +-------+           |
+//        | Outer |           |
+//        +-------+           |
+//            |               |
+//            |   +-------+   |
+//            +-->| Inner |<--+
+//                +-------+
+//
+// Client code references the outer nsIEventTarget which in turn references
+// an inner object.  The inner object is also held alive by the observer
+// service.
+//
+// If the outer object is dereferenced and destroyed, it will trigger a
+// shutdown operation on the inner object.  Similarly if the observer
+// service notifies that the browser is shutting down, then the inner
+// object also starts shutting down.
+//
+// Once the queue has drained we unregister from the observer service.  If
+// the outer object is already gone, then the inner object is free'd at this
+// point.  If the outer object still exists then calls fall back to the
+// ThrottledEventQueue's base target.  We just don't queue things
+// any more.  The inner is then released once the outer object is released.
+//
+// Note, we must keep the inner object alive and attached to the observer
+// service until the TaskQueue is fully shutdown and idle.  We must delay
+// xpcom shutdown if the TaskQueue is in the middle of draining.
+class ThrottledEventQueue::Inner final : public nsIObserver
+{
+  // The runnable which is dispatched to the underlying base target.  Since
+  // we only execute one event at a time we just re-use a single instance
+  // of this class while there are events left in the queue.
+  class Executor final : public Runnable
+  {
+    RefPtr<Inner> mInner;
+
+  public:
+    explicit Executor(Inner* aInner)
+      : mInner(aInner)
+    { }
+
+    NS_IMETHODIMP
+    Run()
+    {
+      mInner->ExecuteRunnable();
+      return NS_OK;
+    }
+  };
+
+  mutable Mutex mMutex;
+  mutable CondVar mIdleCondVar;
+
+  mozilla::CondVar mEventsAvailable;
+
+  // any thread, protected by mutex
+  nsEventQueue mEventQueue;
+
+  // written on main thread, read on any thread
+  nsCOMPtr<nsIEventTarget> mBaseTarget;
+
+  // any thread, protected by mutex
+  nsCOMPtr<nsIRunnable> mExecutor;
+
+  // any thread, atomic
+  Atomic<uint32_t> mExecutionDepth;
+
+  // any thread, protected by mutex
+  bool mShutdownStarted;
+
+  explicit Inner(nsIEventTarget* aBaseTarget)
+    : mMutex("ThrottledEventQueue")
+    , mIdleCondVar(mMutex, "ThrottledEventQueue:Idle")
+    , mEventsAvailable(mMutex, "[ThrottledEventQueue::Inner.mEventsAvailable]")
+    , mEventQueue(mEventsAvailable, nsEventQueue::eNormalQueue)
+    , mBaseTarget(aBaseTarget)
+    , mExecutionDepth(0)
+    , mShutdownStarted(false)
+  {
+  }
+
+  ~Inner()
+  {
+    MOZ_ASSERT(!mExecutor);
+    MOZ_ASSERT(mShutdownStarted);
+  }
+
+  void
+  ExecuteRunnable()
+  {
+    // Any thread
+    nsCOMPtr<nsIRunnable> event;
+    bool shouldShutdown = false;
+
+#ifdef DEBUG
+    bool currentThread = false;
+    mBaseTarget->IsOnCurrentThread(&currentThread);
+    MOZ_ASSERT(currentThread);
+#endif
+
+    {
+      MutexAutoLock lock(mMutex);
+
+      // We only dispatch an executor runnable when we know there is something
+      // in the queue, so this should never fail.
+      MOZ_ALWAYS_TRUE(mEventQueue.GetPendingEvent(getter_AddRefs(event), lock));
+
+      // If there are more events in the queue, then dispatch the next
+      // executor.  We do this now, before running the event, because
+      // the event might spin the event loop and we don't want to stall
+      // the queue.
+      if (mEventQueue.HasPendingEvent(lock)) {
+        // Dispatch the next base target runnable to attempt to execute
+        // the next throttled event.  We must do this before executing
+        // the event in case the event spins the event loop.
+        MOZ_ALWAYS_SUCCEEDS(
+          mBaseTarget->Dispatch(mExecutor, NS_DISPATCH_NORMAL));
+      }
+
+      // Otherwise the queue is empty and we can stop dispatching the
+      // executor.  We might also need to shutdown after running the
+      // last event.
+      else {
+        shouldShutdown = mShutdownStarted;
+        // Note, this breaks a ref cycle.
+        mExecutor = nullptr;
+        mIdleCondVar.NotifyAll();
+      }
+    }
+
+    // Execute the event now that we have unlocked.
+    ++mExecutionDepth;
+    Unused << event->Run();
+    --mExecutionDepth;
+
+    // If shutdown was started and the queue is now empty we can now
+    // finalize the shutdown.  This is performed separately at the end
+    // of the method in order to wait for the event to finish running.
+    if (shouldShutdown) {
+      MOZ_ASSERT(IsEmpty());
+      NS_DispatchToMainThread(NewRunnableMethod(this, &Inner::ShutdownComplete));
+    }
+  }
+
+  void
+  ShutdownComplete()
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+    MOZ_ASSERT(IsEmpty());
+    nsCOMPtr<nsIObserverService> obs = GetObserverService();
+    obs->RemoveObserver(this, kShutdownTopic);
+  }
+
+public:
+  static already_AddRefed<Inner>
+  Create(nsIEventTarget* aBaseTarget)
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+
+    if (ClearOnShutdown_Internal::sCurrentShutdownPhase != ShutdownPhase::NotInShutdown) {
+      return nullptr;
+    }
+
+    nsCOMPtr<nsIObserverService> obs = GetObserverService();
+    if (NS_WARN_IF(!obs)) {
+      return nullptr;
+    }
+
+    RefPtr<Inner> ref = new Inner(aBaseTarget);
+
+    nsresult rv = obs->AddObserver(ref, kShutdownTopic,
+                                   false /* means OS will hold a strong ref */);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      ref->MaybeStartShutdown();
+      MOZ_ASSERT(ref->IsEmpty());
+      return nullptr;
+    }
+
+    return ref.forget();
+  }
+
+  NS_IMETHOD
+  Observe(nsISupports*, const char* aTopic, const char16_t*) override
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+    MOZ_ASSERT(!strcmp(aTopic, kShutdownTopic));
+
+    MaybeStartShutdown();
+
+    // Once shutdown begins we set the Atomic<bool> mShutdownStarted flag.
+    // This prevents any new runnables from being dispatched into the
+    // TaskQueue.  Therefore this loop should be finite.
+    while (!IsEmpty()) {
+      MOZ_ALWAYS_TRUE(NS_ProcessNextEvent());
+    }
+
+    return NS_OK;
+  }
+
+  void
+  MaybeStartShutdown()
+  {
+    // Any thread
+    MutexAutoLock lock(mMutex);
+
+    if (mShutdownStarted) {
+      return;
+    }
+    mShutdownStarted = true;
+
+    // We are marked for shutdown now, but we are still processing runnables.
+    // Return for now.  The shutdown will be completed once the queue is
+    // drained.
+    if (mExecutor) {
+      return;
+    }
+
+    // The queue is empty, so we can complete immediately.
+    NS_DispatchToMainThread(NewRunnableMethod(this, &Inner::ShutdownComplete));
+  }
+
+  bool
+  IsEmpty() const
+  {
+    // Any thread
+    return Length() == 0;
+  }
+
+  uint32_t
+  Length() const
+  {
+    // Any thread
+    MutexAutoLock lock(mMutex);
+    return mEventQueue.Count(lock);
+  }
+
+  void
+  AwaitIdle() const
+  {
+    // Any thread, except the main thread or our base target.  Blocking the
+    // main thread is forbidden.  Blocking the base target is guaranteed to
+    // produce a deadlock.
+    MOZ_ASSERT(!NS_IsMainThread());
+#ifdef DEBUG
+    bool onBaseTarget = false;
+    Unused << mBaseTarget->IsOnCurrentThread(&onBaseTarget);
+    MOZ_ASSERT(!onBaseTarget);
+#endif
+
+    MutexAutoLock lock(mMutex);
+    while (mExecutor) {
+      mIdleCondVar.Wait();
+    }
+  }
+
+  nsresult
+  DispatchFromScript(nsIRunnable* aEvent, uint32_t aFlags)
+  {
+    // Any thread
+    nsCOMPtr<nsIRunnable> r = aEvent;
+    return Dispatch(r.forget(), aFlags);
+  }
+
+  nsresult
+  Dispatch(already_AddRefed<nsIRunnable> aEvent, uint32_t aFlags)
+  {
+    MOZ_ASSERT(aFlags == NS_DISPATCH_NORMAL ||
+               aFlags == NS_DISPATCH_AT_END);
+
+    // Any thread
+    MutexAutoLock lock(mMutex);
+
+    // If we are shutting down, just fall back to our base target
+    // directly.
+    if (mShutdownStarted) {
+      return mBaseTarget->Dispatch(Move(aEvent), aFlags);
+    }
+
+    // We are not currently processing events, so we must start
+    // operating on our base target.  This is fallible, so do
+    // it first.  Our lock will prevent the executor from accessing
+    // the event queue before we add the event below.
+    if (!mExecutor) {
+      // Note, this creates a ref cycle keeping the inner alive
+      // until the queue is drained.
+      mExecutor = new Executor(this);
+      nsresult rv = mBaseTarget->Dispatch(mExecutor, NS_DISPATCH_NORMAL);
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        mExecutor = nullptr;
+        return rv;
+      }
+    }
+
+    // Only add the event to the underlying queue if are able to
+    // dispatch to our base target.
+    mEventQueue.PutEvent(Move(aEvent), lock);
+    return NS_OK;
+  }
+
+  nsresult
+  DelayedDispatch(already_AddRefed<nsIRunnable> aEvent, uint32_t aDelay)
+  {
+    // The base target may implement this, but we don't.  Always fail
+    // to provide consistent behavior.
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  nsresult
+  IsOnCurrentThread(bool* aResult)
+  {
+    // Any thread
+
+    bool shutdownAndIdle = false;
+    {
+      MutexAutoLock lock(mMutex);
+      shutdownAndIdle = mShutdownStarted && mEventQueue.Count(lock) == 0;
+    }
+
+    bool onBaseTarget = false;
+    nsresult rv = mBaseTarget->IsOnCurrentThread(&onBaseTarget);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    // We consider the current stack on this event target if are on
+    // the base target and one of the following is true
+    //  1) We are currently running an event OR
+    //  2) We are both shutting down and the queue is idle
+    *aResult = onBaseTarget && (mExecutionDepth || shutdownAndIdle);
+
+    return NS_OK;
+  }
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+};
+
+NS_IMPL_ISUPPORTS(ThrottledEventQueue::Inner, nsIObserver);
+
+NS_IMPL_ISUPPORTS(ThrottledEventQueue, nsIEventTarget);
+
+ThrottledEventQueue::ThrottledEventQueue(already_AddRefed<Inner> aInner)
+  : mInner(aInner)
+{
+  MOZ_ASSERT(mInner);
+}
+
+ThrottledEventQueue::~ThrottledEventQueue()
+{
+  mInner->MaybeStartShutdown();
+}
+
+void
+ThrottledEventQueue::MaybeStartShutdown()
+{
+  return mInner->MaybeStartShutdown();
+}
+
+already_AddRefed<ThrottledEventQueue>
+ThrottledEventQueue::Create(nsIEventTarget* aBaseTarget)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aBaseTarget);
+
+  RefPtr<Inner> inner = Inner::Create(aBaseTarget);
+  if (NS_WARN_IF(!inner)) {
+    return nullptr;
+  }
+
+  RefPtr<ThrottledEventQueue> ref =
+    new ThrottledEventQueue(inner.forget());
+  return ref.forget();
+}
+
+bool
+ThrottledEventQueue::IsEmpty() const
+{
+  return mInner->IsEmpty();
+}
+
+uint32_t
+ThrottledEventQueue::Length() const
+{
+  return mInner->Length();
+}
+
+void
+ThrottledEventQueue::AwaitIdle() const
+{
+  return mInner->AwaitIdle();
+}
+
+NS_IMETHODIMP
+ThrottledEventQueue::DispatchFromScript(nsIRunnable* aEvent, uint32_t aFlags)
+{
+  return mInner->DispatchFromScript(aEvent, aFlags);
+}
+
+NS_IMETHODIMP
+ThrottledEventQueue::Dispatch(already_AddRefed<nsIRunnable> aEvent,
+                                     uint32_t aFlags)
+{
+  return mInner->Dispatch(Move(aEvent), aFlags);
+}
+
+NS_IMETHODIMP
+ThrottledEventQueue::DelayedDispatch(already_AddRefed<nsIRunnable> aEvent,
+                                            uint32_t aFlags)
+{
+  return mInner->DelayedDispatch(Move(aEvent), aFlags);
+}
+
+NS_IMETHODIMP
+ThrottledEventQueue::IsOnCurrentThread(bool* aResult)
+{
+  return mInner->IsOnCurrentThread(aResult);
+}
+
+} // namespace mozilla
diff --git a/xpcom/threads/ThrottledEventQueue.h b/xpcom/threads/ThrottledEventQueue.h
new file mode 100644
index 000000000..e0762bcce
--- /dev/null
+++ b/xpcom/threads/ThrottledEventQueue.h
@@ -0,0 +1,94 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// nsIEventTarget wrapper for throttling event dispatch.
+
+#ifndef mozilla_ThrottledEventQueue_h
+#define mozilla_ThrottledEventQueue_h
+
+#include "nsIEventTarget.h"
+
+namespace mozilla {
+
+// A ThrottledEventQueue is an event target that can be used to throttle
+// events being dispatched to another base target.  It maintains its
+// own queue of events and only dispatches one at a time to the wrapped
+// target.  This can be used to avoid flooding the base target.
+//
+// Flooding is avoided via a very simply principal.  Runnables dispatched
+// to the ThrottledEventQueue are only dispatched to the base target
+// one at a time.  Only once that runnable has executed will we dispatch
+// the next runnable to the base target.  This in effect makes all
+// runnables passing through the ThrottledEventQueue yield to other work
+// on the base target.
+//
+// ThrottledEventQueue keeps runnables waiting to be dispatched to the
+// base in its own internal queue.  Code can query the length of this
+// queue using IsEmpty() and Length().  Further, code implement back
+// pressure by checking the depth of the queue and deciding to stop
+// issuing runnables if they see the ThrottledEventQueue is backed up.
+// Code running on other threads could even use AwaitIdle() to block
+// all operation until the ThrottledEventQueue drains.
+//
+// Note, this class is similar to TaskQueue, but also differs in a few
+// ways.  First, it is a very simple nsIEventTarget implementation.  It
+// does not use the AbstractThread API.
+//
+// In addition, ThrottledEventQueue currently dispatches its next
+// runnable to the base target *before* running the current event.  This
+// allows the event code to spin the event loop without stalling the
+// ThrottledEventQueue.  In contrast, TaskQueue only dispatches its next
+// runnable after running the current event.  That approach is necessary
+// for TaskQueue in order to work with thread pool targets.
+//
+// So, if you are targeting a thread pool you probably want a TaskQueue.
+// If you are targeting a single thread or other non-concurrent event
+// target, you probably want a ThrottledEventQueue.
+//
+// ThrottledEventQueue also implements an automatic shutdown mechanism.
+// De-referencing the queue or browser shutdown will automatically begin
+// shutdown.
+//
+// Once shutdown begins all events will bypass the queue and be dispatched
+// straight to the underlying base target.
+class ThrottledEventQueue final : public nsIEventTarget
+{
+  class Inner;
+  RefPtr<Inner> mInner;
+
+  explicit ThrottledEventQueue(already_AddRefed<Inner> aInner);
+  ~ThrottledEventQueue();
+
+  // Begin shutdown of the event queue.  This has no effect if shutdown
+  // is already in process.  After this is called nsIEventTarget methods
+  // will bypass the queue and operate directly on the base target.
+  // Note, this could be made public if code needs to explicitly shutdown
+  // for some reason.
+  void MaybeStartShutdown();
+
+public:
+  // Attempt to create a ThrottledEventQueue for the given target.  This
+  // may return nullptr if the browser is already shutting down.
+  static already_AddRefed<ThrottledEventQueue>
+  Create(nsIEventTarget* aBaseTarget);
+
+  // Determine if there are any events pending in the queue.
+  bool IsEmpty() const;
+
+  // Determine how many events are pending in the queue.
+  uint32_t Length() const;
+
+  // Block the current thread until the queue is empty.  This may not
+  // be called on the main thread or the base target.
+  void AwaitIdle() const;
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIEVENTTARGET
+};
+
+} // namespace mozilla
+
+#endif // mozilla_ThrottledEventQueue_h
diff --git a/xpcom/threads/TimerThread.cpp b/xpcom/threads/TimerThread.cpp
new file mode 100644
index 000000000..0127e2dd1
--- /dev/null
+++ b/xpcom/threads/TimerThread.cpp
@@ -0,0 +1,752 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsTimerImpl.h"
+#include "TimerThread.h"
+
+#include "nsThreadUtils.h"
+#include "plarena.h"
+#include "pratom.h"
+
+#include "nsIObserverService.h"
+#include "nsIServiceManager.h"
+#include "mozilla/Services.h"
+#include "mozilla/ChaosMode.h"
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/BinarySearch.h"
+
+#include <math.h>
+
+using namespace mozilla;
+#ifdef MOZ_TASK_TRACER
+#include "GeckoTaskTracerImpl.h"
+using namespace mozilla::tasktracer;
+#endif
+
+NS_IMPL_ISUPPORTS(TimerThread, nsIRunnable, nsIObserver)
+
+TimerThread::TimerThread() :
+  mInitInProgress(false),
+  mInitialized(false),
+  mMonitor("TimerThread.mMonitor"),
+  mShutdown(false),
+  mWaiting(false),
+  mNotified(false),
+  mSleeping(false)
+{
+}
+
+TimerThread::~TimerThread()
+{
+  mThread = nullptr;
+
+  NS_ASSERTION(mTimers.IsEmpty(), "Timers remain in TimerThread::~TimerThread");
+}
+
+nsresult
+TimerThread::InitLocks()
+{
+  return NS_OK;
+}
+
+namespace {
+
+class TimerObserverRunnable : public Runnable
+{
+public:
+  explicit TimerObserverRunnable(nsIObserver* aObserver)
+    : mObserver(aObserver)
+  {
+  }
+
+  NS_DECL_NSIRUNNABLE
+
+private:
+  nsCOMPtr<nsIObserver> mObserver;
+};
+
+NS_IMETHODIMP
+TimerObserverRunnable::Run()
+{
+  nsCOMPtr<nsIObserverService> observerService =
+    mozilla::services::GetObserverService();
+  if (observerService) {
+    observerService->AddObserver(mObserver, "sleep_notification", false);
+    observerService->AddObserver(mObserver, "wake_notification", false);
+    observerService->AddObserver(mObserver, "suspend_process_notification", false);
+    observerService->AddObserver(mObserver, "resume_process_notification", false);
+  }
+  return NS_OK;
+}
+
+} // namespace
+
+namespace {
+
+// TimerEventAllocator is a thread-safe allocator used only for nsTimerEvents.
+// It's needed to avoid contention over the default allocator lock when
+// firing timer events (see bug 733277).  The thread-safety is required because
+// nsTimerEvent objects are allocated on the timer thread, and freed on another
+// thread.  Because TimerEventAllocator has its own lock, contention over that
+// lock is limited to the allocation and deallocation of nsTimerEvent objects.
+//
+// Because this allocator is layered over PLArenaPool, it never shrinks -- even
+// "freed" nsTimerEvents aren't truly freed, they're just put onto a free-list
+// for later recycling.  So the amount of memory consumed will always be equal
+// to the high-water mark consumption.  But nsTimerEvents are small and it's
+// unusual to have more than a few hundred of them, so this shouldn't be a
+// problem in practice.
+
+class TimerEventAllocator
+{
+private:
+  struct FreeEntry
+  {
+    FreeEntry* mNext;
+  };
+
+  PLArenaPool mPool;
+  FreeEntry* mFirstFree;
+  mozilla::Monitor mMonitor;
+
+public:
+  TimerEventAllocator()
+    : mFirstFree(nullptr)
+    , mMonitor("TimerEventAllocator")
+  {
+    PL_InitArenaPool(&mPool, "TimerEventPool", 4096, /* align = */ 0);
+  }
+
+  ~TimerEventAllocator()
+  {
+    PL_FinishArenaPool(&mPool);
+  }
+
+  void* Alloc(size_t aSize);
+  void Free(void* aPtr);
+};
+
+} // namespace
+
+// This is a nsICancelableRunnable because we can dispatch it to Workers and
+// those can be shut down at any time, and in these cases, Cancel() is called
+// instead of Run().
+class nsTimerEvent final : public CancelableRunnable
+{
+public:
+  NS_IMETHOD Run() override;
+
+  nsresult Cancel() override
+  {
+    // Since nsTimerImpl is not thread-safe, we should release |mTimer|
+    // here in the target thread to avoid race condition. Otherwise,
+    // ~nsTimerEvent() which calls nsTimerImpl::Release() could run in the
+    // timer thread and result in race condition.
+    mTimer = nullptr;
+    return NS_OK;
+  }
+
+  nsTimerEvent()
+    : mTimer()
+    , mGeneration(0)
+  {
+    // Note: We override operator new for this class, and the override is
+    // fallible!
+    sAllocatorUsers++;
+  }
+
+  TimeStamp mInitTime;
+
+  static void Init();
+  static void Shutdown();
+  static void DeleteAllocatorIfNeeded();
+
+  static void* operator new(size_t aSize) CPP_THROW_NEW
+  {
+    return sAllocator->Alloc(aSize);
+  }
+  void operator delete(void* aPtr)
+  {
+    sAllocator->Free(aPtr);
+    DeleteAllocatorIfNeeded();
+  }
+
+  already_AddRefed<nsTimerImpl> ForgetTimer()
+  {
+    return mTimer.forget();
+  }
+
+  void SetTimer(already_AddRefed<nsTimerImpl> aTimer)
+  {
+    mTimer = aTimer;
+    mGeneration = mTimer->GetGeneration();
+  }
+
+private:
+  nsTimerEvent(const nsTimerEvent&) = delete;
+  nsTimerEvent& operator=(const nsTimerEvent&) = delete;
+  nsTimerEvent& operator=(const nsTimerEvent&&) = delete;
+
+  ~nsTimerEvent()
+  {
+    MOZ_ASSERT(!sCanDeleteAllocator || sAllocatorUsers > 0,
+               "This will result in us attempting to deallocate the nsTimerEvent allocator twice");
+    sAllocatorUsers--;
+  }
+
+  RefPtr<nsTimerImpl> mTimer;
+  int32_t      mGeneration;
+
+  static TimerEventAllocator* sAllocator;
+  static Atomic<int32_t> sAllocatorUsers;
+  static bool sCanDeleteAllocator;
+};
+
+TimerEventAllocator* nsTimerEvent::sAllocator = nullptr;
+Atomic<int32_t> nsTimerEvent::sAllocatorUsers;
+bool nsTimerEvent::sCanDeleteAllocator = false;
+
+namespace {
+
+void*
+TimerEventAllocator::Alloc(size_t aSize)
+{
+  MOZ_ASSERT(aSize == sizeof(nsTimerEvent));
+
+  mozilla::MonitorAutoLock lock(mMonitor);
+
+  void* p;
+  if (mFirstFree) {
+    p = mFirstFree;
+    mFirstFree = mFirstFree->mNext;
+  } else {
+    PL_ARENA_ALLOCATE(p, &mPool, aSize);
+    if (!p) {
+      return nullptr;
+    }
+  }
+
+  return p;
+}
+
+void
+TimerEventAllocator::Free(void* aPtr)
+{
+  mozilla::MonitorAutoLock lock(mMonitor);
+
+  FreeEntry* entry = reinterpret_cast<FreeEntry*>(aPtr);
+
+  entry->mNext = mFirstFree;
+  mFirstFree = entry;
+}
+
+} // namespace
+
+void
+nsTimerEvent::Init()
+{
+  sAllocator = new TimerEventAllocator();
+}
+
+void
+nsTimerEvent::Shutdown()
+{
+  sCanDeleteAllocator = true;
+  DeleteAllocatorIfNeeded();
+}
+
+void
+nsTimerEvent::DeleteAllocatorIfNeeded()
+{
+  if (sCanDeleteAllocator && sAllocatorUsers == 0) {
+    delete sAllocator;
+    sAllocator = nullptr;
+  }
+}
+
+NS_IMETHODIMP
+nsTimerEvent::Run()
+{
+  if (!mTimer) {
+    MOZ_ASSERT(false);
+    return NS_OK;
+  }
+
+  if (MOZ_LOG_TEST(GetTimerLog(), LogLevel::Debug)) {
+    TimeStamp now = TimeStamp::Now();
+    MOZ_LOG(GetTimerLog(), LogLevel::Debug,
+           ("[this=%p] time between PostTimerEvent() and Fire(): %fms\n",
+            this, (now - mInitTime).ToMilliseconds()));
+  }
+
+  mTimer->Fire(mGeneration);
+
+  // We call Cancel() to correctly release mTimer.
+  // Read more in the Cancel() implementation.
+  return Cancel();
+}
+
+nsresult
+TimerThread::Init()
+{
+  MOZ_LOG(GetTimerLog(), LogLevel::Debug,
+         ("TimerThread::Init [%d]\n", mInitialized));
+
+  if (mInitialized) {
+    if (!mThread) {
+      return NS_ERROR_FAILURE;
+    }
+
+    return NS_OK;
+  }
+
+  nsTimerEvent::Init();
+
+  if (mInitInProgress.exchange(true) == false) {
+    // We hold on to mThread to keep the thread alive.
+    nsresult rv = NS_NewThread(getter_AddRefs(mThread), this);
+    if (NS_FAILED(rv)) {
+      mThread = nullptr;
+    } else {
+      RefPtr<TimerObserverRunnable> r = new TimerObserverRunnable(this);
+      if (NS_IsMainThread()) {
+        r->Run();
+      } else {
+        NS_DispatchToMainThread(r);
+      }
+    }
+
+    {
+      MonitorAutoLock lock(mMonitor);
+      mInitialized = true;
+      mMonitor.NotifyAll();
+    }
+  } else {
+    MonitorAutoLock lock(mMonitor);
+    while (!mInitialized) {
+      mMonitor.Wait();
+    }
+  }
+
+  if (!mThread) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+nsresult
+TimerThread::Shutdown()
+{
+  MOZ_LOG(GetTimerLog(), LogLevel::Debug, ("TimerThread::Shutdown begin\n"));
+
+  if (!mThread) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  nsTArray<nsTimerImpl*> timers;
+  {
+    // lock scope
+    MonitorAutoLock lock(mMonitor);
+
+    mShutdown = true;
+
+    // notify the cond var so that Run() can return
+    if (mWaiting) {
+      mNotified = true;
+      mMonitor.Notify();
+    }
+
+    // Need to copy content of mTimers array to a local array
+    // because call to timers' Cancel() (and release its self)
+    // must not be done under the lock. Destructor of a callback
+    // might potentially call some code reentering the same lock
+    // that leads to unexpected behavior or deadlock.
+    // See bug 422472.
+    timers.AppendElements(mTimers);
+    mTimers.Clear();
+  }
+
+  uint32_t timersCount = timers.Length();
+  for (uint32_t i = 0; i < timersCount; i++) {
+    nsTimerImpl* timer = timers[i];
+    timer->Cancel();
+    ReleaseTimerInternal(timer);
+  }
+
+  mThread->Shutdown();    // wait for the thread to die
+
+  nsTimerEvent::Shutdown();
+
+  MOZ_LOG(GetTimerLog(), LogLevel::Debug, ("TimerThread::Shutdown end\n"));
+  return NS_OK;
+}
+
+namespace {
+
+struct MicrosecondsToInterval
+{
+  PRIntervalTime operator[](size_t aMs) const {
+    return PR_MicrosecondsToInterval(aMs);
+  }
+};
+
+struct IntervalComparator
+{
+  int operator()(PRIntervalTime aInterval) const {
+    return (0 < aInterval) ? -1 : 1;
+  }
+};
+
+} // namespace
+
+NS_IMETHODIMP
+TimerThread::Run()
+{
+  PR_SetCurrentThreadName("Timer");
+
+  MonitorAutoLock lock(mMonitor);
+
+  // We need to know how many microseconds give a positive PRIntervalTime. This
+  // is platform-dependent and we calculate it at runtime, finding a value |v|
+  // such that |PR_MicrosecondsToInterval(v) > 0| and then binary-searching in
+  // the range [0, v) to find the ms-to-interval scale.
+  uint32_t usForPosInterval = 1;
+  while (PR_MicrosecondsToInterval(usForPosInterval) == 0) {
+    usForPosInterval <<= 1;
+  }
+
+  size_t usIntervalResolution;
+  BinarySearchIf(MicrosecondsToInterval(), 0, usForPosInterval, IntervalComparator(), &usIntervalResolution);
+  MOZ_ASSERT(PR_MicrosecondsToInterval(usIntervalResolution - 1) == 0);
+  MOZ_ASSERT(PR_MicrosecondsToInterval(usIntervalResolution) == 1);
+
+  // Half of the amount of microseconds needed to get positive PRIntervalTime.
+  // We use this to decide how to round our wait times later
+  int32_t halfMicrosecondsIntervalResolution = usIntervalResolution / 2;
+  bool forceRunNextTimer = false;
+
+  while (!mShutdown) {
+    // Have to use PRIntervalTime here, since PR_WaitCondVar takes it
+    PRIntervalTime waitFor;
+    bool forceRunThisTimer = forceRunNextTimer;
+    forceRunNextTimer = false;
+
+    if (mSleeping) {
+      // Sleep for 0.1 seconds while not firing timers.
+      uint32_t milliseconds = 100;
+      if (ChaosMode::isActive(ChaosFeature::TimerScheduling)) {
+        milliseconds = ChaosMode::randomUint32LessThan(200);
+      }
+      waitFor = PR_MillisecondsToInterval(milliseconds);
+    } else {
+      waitFor = PR_INTERVAL_NO_TIMEOUT;
+      TimeStamp now = TimeStamp::Now();
+      nsTimerImpl* timer = nullptr;
+
+      if (!mTimers.IsEmpty()) {
+        timer = mTimers[0];
+
+        if (now >= timer->mTimeout || forceRunThisTimer) {
+    next:
+          // NB: AddRef before the Release under RemoveTimerInternal to avoid
+          // mRefCnt passing through zero, in case all other refs than the one
+          // from mTimers have gone away (the last non-mTimers[i]-ref's Release
+          // must be racing with us, blocked in gThread->RemoveTimer waiting
+          // for TimerThread::mMonitor, under nsTimerImpl::Release.
+
+          RefPtr<nsTimerImpl> timerRef(timer);
+          RemoveTimerInternal(timer);
+          timer = nullptr;
+
+          MOZ_LOG(GetTimerLog(), LogLevel::Debug,
+                 ("Timer thread woke up %fms from when it was supposed to\n",
+                  fabs((now - timerRef->mTimeout).ToMilliseconds())));
+
+          // We are going to let the call to PostTimerEvent here handle the
+          // release of the timer so that we don't end up releasing the timer
+          // on the TimerThread instead of on the thread it targets.
+          timerRef = PostTimerEvent(timerRef.forget());
+
+          if (timerRef) {
+            // We got our reference back due to an error.
+            // Unhook the nsRefPtr, and release manually so we can get the
+            // refcount.
+            nsrefcnt rc = timerRef.forget().take()->Release();
+            (void)rc;
+
+            // The nsITimer interface requires that its users keep a reference
+            // to the timers they use while those timers are initialized but
+            // have not yet fired.  If this ever happens, it is a bug in the
+            // code that created and used the timer.
+            //
+            // Further, note that this should never happen even with a
+            // misbehaving user, because nsTimerImpl::Release checks for a
+            // refcount of 1 with an armed timer (a timer whose only reference
+            // is from the timer thread) and when it hits this will remove the
+            // timer from the timer thread and thus destroy the last reference,
+            // preventing this situation from occurring.
+            MOZ_ASSERT(rc != 0, "destroyed timer off its target thread!");
+          }
+
+          if (mShutdown) {
+            break;
+          }
+
+          // Update now, as PostTimerEvent plus the locking may have taken a
+          // tick or two, and we may goto next below.
+          now = TimeStamp::Now();
+        }
+      }
+
+      if (!mTimers.IsEmpty()) {
+        timer = mTimers[0];
+
+        TimeStamp timeout = timer->mTimeout;
+
+        // Don't wait at all (even for PR_INTERVAL_NO_WAIT) if the next timer
+        // is due now or overdue.
+        //
+        // Note that we can only sleep for integer values of a certain
+        // resolution. We use halfMicrosecondsIntervalResolution, calculated
+        // before, to do the optimal rounding (i.e., of how to decide what
+        // interval is so small we should not wait at all).
+        double microseconds = (timeout - now).ToMilliseconds() * 1000;
+
+        if (ChaosMode::isActive(ChaosFeature::TimerScheduling)) {
+          // The mean value of sFractions must be 1 to ensure that
+          // the average of a long sequence of timeouts converges to the
+          // actual sum of their times.
+          static const float sFractions[] = {
+            0.0f, 0.25f, 0.5f, 0.75f, 1.0f, 1.75f, 2.75f
+          };
+          microseconds *=
+            sFractions[ChaosMode::randomUint32LessThan(ArrayLength(sFractions))];
+          forceRunNextTimer = true;
+        }
+
+        if (microseconds < halfMicrosecondsIntervalResolution) {
+          forceRunNextTimer = false;
+          goto next; // round down; execute event now
+        }
+        waitFor = PR_MicrosecondsToInterval(
+          static_cast<uint32_t>(microseconds)); // Floor is accurate enough.
+        if (waitFor == 0) {
+          waitFor = 1;  // round up, wait the minimum time we can wait
+        }
+      }
+
+      if (MOZ_LOG_TEST(GetTimerLog(), LogLevel::Debug)) {
+        if (waitFor == PR_INTERVAL_NO_TIMEOUT)
+          MOZ_LOG(GetTimerLog(), LogLevel::Debug,
+                 ("waiting for PR_INTERVAL_NO_TIMEOUT\n"));
+        else
+          MOZ_LOG(GetTimerLog(), LogLevel::Debug,
+                 ("waiting for %u\n", PR_IntervalToMilliseconds(waitFor)));
+      }
+    }
+
+    mWaiting = true;
+    mNotified = false;
+    mMonitor.Wait(waitFor);
+    if (mNotified) {
+      forceRunNextTimer = false;
+    }
+    mWaiting = false;
+  }
+
+  return NS_OK;
+}
+
+nsresult
+TimerThread::AddTimer(nsTimerImpl* aTimer)
+{
+  MonitorAutoLock lock(mMonitor);
+
+  if (!aTimer->mEventTarget) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  // Add the timer to our list.
+  int32_t i = AddTimerInternal(aTimer);
+  if (i < 0) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  // Awaken the timer thread.
+  if (mWaiting && i == 0) {
+    mNotified = true;
+    mMonitor.Notify();
+  }
+
+  return NS_OK;
+}
+
+nsresult
+TimerThread::RemoveTimer(nsTimerImpl* aTimer)
+{
+  MonitorAutoLock lock(mMonitor);
+
+  // Remove the timer from our array.  Tell callers that aTimer was not found
+  // by returning NS_ERROR_NOT_AVAILABLE.
+
+  if (!RemoveTimerInternal(aTimer)) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  // Awaken the timer thread.
+  if (mWaiting) {
+    mNotified = true;
+    mMonitor.Notify();
+  }
+
+  return NS_OK;
+}
+
+// This function must be called from within a lock
+int32_t
+TimerThread::AddTimerInternal(nsTimerImpl* aTimer)
+{
+  mMonitor.AssertCurrentThreadOwns();
+  if (mShutdown) {
+    return -1;
+  }
+
+  TimeStamp now = TimeStamp::Now();
+
+  TimerAdditionComparator c(now, aTimer);
+  nsTimerImpl** insertSlot = mTimers.InsertElementSorted(aTimer, c);
+
+  if (!insertSlot) {
+    return -1;
+  }
+
+  NS_ADDREF(aTimer);
+
+#ifdef MOZ_TASK_TRACER
+  // Caller of AddTimer is the parent task of its timer event, so we store the
+  // TraceInfo here for later used.
+  aTimer->GetTLSTraceInfo();
+#endif
+
+  return insertSlot - mTimers.Elements();
+}
+
+bool
+TimerThread::RemoveTimerInternal(nsTimerImpl* aTimer)
+{
+  mMonitor.AssertCurrentThreadOwns();
+  if (!mTimers.RemoveElement(aTimer)) {
+    return false;
+  }
+
+  ReleaseTimerInternal(aTimer);
+  return true;
+}
+
+void
+TimerThread::ReleaseTimerInternal(nsTimerImpl* aTimer)
+{
+  if (!mShutdown) {
+    // copied to a local array before releasing in shutdown
+    mMonitor.AssertCurrentThreadOwns();
+  }
+  NS_RELEASE(aTimer);
+}
+
+already_AddRefed<nsTimerImpl>
+TimerThread::PostTimerEvent(already_AddRefed<nsTimerImpl> aTimerRef)
+{
+  mMonitor.AssertCurrentThreadOwns();
+
+  RefPtr<nsTimerImpl> timer(aTimerRef);
+  if (!timer->mEventTarget) {
+    NS_ERROR("Attempt to post timer event to NULL event target");
+    return timer.forget();
+  }
+
+  // XXX we may want to reuse this nsTimerEvent in the case of repeating timers.
+
+  // Since we already addref'd 'timer', we don't need to addref here.
+  // We will release either in ~nsTimerEvent(), or pass the reference back to
+  // the caller. We need to copy the generation number from this timer into the
+  // event, so we can avoid firing a timer that was re-initialized after being
+  // canceled.
+
+  RefPtr<nsTimerEvent> event = new nsTimerEvent;
+  if (!event) {
+    return timer.forget();
+  }
+
+  if (MOZ_LOG_TEST(GetTimerLog(), LogLevel::Debug)) {
+    event->mInitTime = TimeStamp::Now();
+  }
+
+#ifdef MOZ_TASK_TRACER
+  // During the dispatch of TimerEvent, we overwrite the current TraceInfo
+  // partially with the info saved in timer earlier, and restore it back by
+  // AutoSaveCurTraceInfo.
+  AutoSaveCurTraceInfo saveCurTraceInfo;
+  (timer->GetTracedTask()).SetTLSTraceInfo();
+#endif
+
+  nsCOMPtr<nsIEventTarget> target = timer->mEventTarget;
+  event->SetTimer(timer.forget());
+
+  nsresult rv;
+  {
+    // We release mMonitor around the Dispatch because if this timer is targeted
+    // at the TimerThread we'll deadlock.
+    MonitorAutoUnlock unlock(mMonitor);
+    rv = target->Dispatch(event, NS_DISPATCH_NORMAL);
+  }
+
+  if (NS_FAILED(rv)) {
+    timer = event->ForgetTimer();
+    RemoveTimerInternal(timer);
+    return timer.forget();
+  }
+
+  return nullptr;
+}
+
+void
+TimerThread::DoBeforeSleep()
+{
+  // Mainthread
+  MonitorAutoLock lock(mMonitor);
+  mSleeping = true;
+}
+
+// Note: wake may be notified without preceding sleep notification
+void
+TimerThread::DoAfterSleep()
+{
+  // Mainthread
+  MonitorAutoLock lock(mMonitor);
+  mSleeping = false;
+
+  // Wake up the timer thread to re-process the array to ensure the sleep delay is correct,
+  // and fire any expired timers (perhaps quite a few)
+  mNotified = true;
+  mMonitor.Notify();
+}
+
+
+NS_IMETHODIMP
+TimerThread::Observe(nsISupports* /* aSubject */, const char* aTopic,
+                     const char16_t* /* aData */)
+{
+  if (strcmp(aTopic, "sleep_notification") == 0 ||
+      strcmp(aTopic, "suspend_process_notification") == 0) {
+    DoBeforeSleep();
+  } else if (strcmp(aTopic, "wake_notification") == 0 ||
+             strcmp(aTopic, "resume_process_notification") == 0) {
+    DoAfterSleep();
+  }
+
+  return NS_OK;
+}
diff --git a/xpcom/threads/TimerThread.h b/xpcom/threads/TimerThread.h
new file mode 100644
index 000000000..a7204810a
--- /dev/null
+++ b/xpcom/threads/TimerThread.h
@@ -0,0 +1,115 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef TimerThread_h___
+#define TimerThread_h___
+
+#include "nsIObserver.h"
+#include "nsIRunnable.h"
+#include "nsIThread.h"
+
+#include "nsTimerImpl.h"
+#include "nsThreadUtils.h"
+
+#include "nsTArray.h"
+
+#include "mozilla/Atomics.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Monitor.h"
+
+namespace mozilla {
+class TimeStamp;
+} // namespace mozilla
+
+class TimerThread final
+  : public nsIRunnable
+  , public nsIObserver
+{
+public:
+  typedef mozilla::Monitor Monitor;
+  typedef mozilla::TimeStamp TimeStamp;
+  typedef mozilla::TimeDuration TimeDuration;
+
+  TimerThread();
+  nsresult InitLocks();
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIRUNNABLE
+  NS_DECL_NSIOBSERVER
+
+  nsresult Init();
+  nsresult Shutdown();
+
+  nsresult AddTimer(nsTimerImpl* aTimer);
+  nsresult RemoveTimer(nsTimerImpl* aTimer);
+
+  void DoBeforeSleep();
+  void DoAfterSleep();
+
+  bool IsOnTimerThread() const
+  {
+    return mThread == NS_GetCurrentThread();
+  }
+
+private:
+  ~TimerThread();
+
+  mozilla::Atomic<bool> mInitInProgress;
+  bool    mInitialized;
+
+  // These two internal helper methods must be called while mMonitor is held.
+  // AddTimerInternal returns the position where the timer was added in the
+  // list, or -1 if it failed.
+  int32_t AddTimerInternal(nsTimerImpl* aTimer);
+  bool    RemoveTimerInternal(nsTimerImpl* aTimer);
+  void    ReleaseTimerInternal(nsTimerImpl* aTimer);
+
+  already_AddRefed<nsTimerImpl> PostTimerEvent(already_AddRefed<nsTimerImpl> aTimerRef);
+
+  nsCOMPtr<nsIThread> mThread;
+  Monitor mMonitor;
+
+  bool mShutdown;
+  bool mWaiting;
+  bool mNotified;
+  bool mSleeping;
+
+  nsTArray<nsTimerImpl*> mTimers;
+};
+
+struct TimerAdditionComparator
+{
+  TimerAdditionComparator(const mozilla::TimeStamp& aNow,
+                          nsTimerImpl* aTimerToInsert) :
+    now(aNow)
+#ifdef DEBUG
+    , timerToInsert(aTimerToInsert)
+#endif
+  {
+  }
+
+  bool LessThan(nsTimerImpl* aFromArray, nsTimerImpl* aNewTimer) const
+  {
+    MOZ_ASSERT(aNewTimer == timerToInsert, "Unexpected timer ordering");
+
+    // Skip any overdue timers.
+    return aFromArray->mTimeout <= now ||
+           aFromArray->mTimeout <= aNewTimer->mTimeout;
+  }
+
+  bool Equals(nsTimerImpl* aFromArray, nsTimerImpl* aNewTimer) const
+  {
+    return false;
+  }
+
+private:
+  const mozilla::TimeStamp& now;
+#ifdef DEBUG
+  const nsTimerImpl* const timerToInsert;
+#endif
+};
+
+#endif /* TimerThread_h___ */
diff --git a/xpcom/threads/moz.build b/xpcom/threads/moz.build
new file mode 100644
index 000000000..5d54a4bf4
--- /dev/null
+++ b/xpcom/threads/moz.build
@@ -0,0 +1,89 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+XPIDL_SOURCES += [
+    'nsIEnvironment.idl',
+    'nsIEventTarget.idl',
+    'nsIIdlePeriod.idl',
+    'nsIProcess.idl',
+    'nsIRunnable.idl',
+    'nsISupportsPriority.idl',
+    'nsIThread.idl',
+    'nsIThreadInternal.idl',
+    'nsIThreadManager.idl',
+    'nsIThreadPool.idl',
+    'nsITimer.idl',
+]
+
+XPIDL_MODULE = 'xpcom_threads'
+
+EXPORTS += [
+    'nsEventQueue.h',
+    'nsICancelableRunnable.h',
+    'nsIIncrementalRunnable.h',
+    'nsMemoryPressure.h',
+    'nsProcess.h',
+    'nsThread.h',
+]
+
+EXPORTS.mozilla += [
+    'AbstractThread.h',
+    'BackgroundHangMonitor.h',
+    'HangAnnotations.h',
+    'HangMonitor.h',
+    'LazyIdleThread.h',
+    'MainThreadIdlePeriod.h',
+    'MozPromise.h',
+    'SharedThreadPool.h',
+    'StateMirroring.h',
+    'StateWatching.h',
+    'SyncRunnable.h',
+    'TaskDispatcher.h',
+    'TaskQueue.h',
+    'ThrottledEventQueue.h',
+]
+
+UNIFIED_SOURCES += [
+    'AbstractThread.cpp',
+    'BackgroundHangMonitor.cpp',
+    'HangAnnotations.cpp',
+    'HangMonitor.cpp',
+    'LazyIdleThread.cpp',
+    'MainThreadIdlePeriod.cpp',
+    'nsEnvironment.cpp',
+    'nsEventQueue.cpp',
+    'nsMemoryPressure.cpp',
+    'nsProcessCommon.cpp',
+    'nsThread.cpp',
+    'nsThreadManager.cpp',
+    'nsThreadPool.cpp',
+    'nsTimerImpl.cpp',
+    'SharedThreadPool.cpp',
+    'TaskQueue.cpp',
+    'ThreadStackHelper.cpp',
+    'ThrottledEventQueue.cpp',
+    'TimerThread.cpp',
+]
+
+LOCAL_INCLUDES += [
+    '../build',
+    '/caps',
+    '/tools/profiler',
+]
+
+# BHR disabled for Release builds because of bug 965392.
+# BHR disabled for debug builds because of bug 979069.
+# BHR disabled on gonk because of bug 1180533
+# BHR disabled for TSan builds because of bug 1121216.
+if CONFIG['MOZ_UPDATE_CHANNEL'] not in ('release') and \
+   not CONFIG['MOZ_DEBUG'] and \
+   not CONFIG['MOZ_WIDGET_TOOLKIT'] == 'gonk' and \
+   not CONFIG['MOZ_TSAN']:
+    DEFINES['MOZ_ENABLE_BACKGROUND_HANG_MONITOR'] = 1
+
+FINAL_LIBRARY = 'xul'
+
+include('/ipc/chromium/chromium-config.mozbuild')
diff --git a/xpcom/threads/nsEnvironment.cpp b/xpcom/threads/nsEnvironment.cpp
new file mode 100644
index 000000000..0de56675e
--- /dev/null
+++ b/xpcom/threads/nsEnvironment.cpp
@@ -0,0 +1,163 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsEnvironment.h"
+#include "prenv.h"
+#include "prprf.h"
+#include "nsBaseHashtable.h"
+#include "nsHashKeys.h"
+#include "nsPromiseFlatString.h"
+#include "nsDependentString.h"
+#include "nsNativeCharsetUtils.h"
+
+using namespace mozilla;
+
+NS_IMPL_ISUPPORTS(nsEnvironment, nsIEnvironment)
+
+nsresult
+nsEnvironment::Create(nsISupports* aOuter, REFNSIID aIID, void** aResult)
+{
+  nsresult rv;
+  *aResult = nullptr;
+
+  if (aOuter) {
+    return NS_ERROR_NO_AGGREGATION;
+  }
+
+  nsEnvironment* obj = new nsEnvironment();
+
+  rv = obj->QueryInterface(aIID, aResult);
+  if (NS_FAILED(rv)) {
+    delete obj;
+  }
+  return rv;
+}
+
+nsEnvironment::~nsEnvironment()
+{
+}
+
+NS_IMETHODIMP
+nsEnvironment::Exists(const nsAString& aName, bool* aOutValue)
+{
+  nsAutoCString nativeName;
+  nsresult rv = NS_CopyUnicodeToNative(aName, nativeName);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  nsAutoCString nativeVal;
+#if defined(XP_UNIX)
+  /* For Unix/Linux platforms we follow the Unix definition:
+   * An environment variable exists when |getenv()| returns a non-nullptr
+   * value. An environment variable does not exist when |getenv()| returns
+   * nullptr.
+   */
+  const char* value = PR_GetEnv(nativeName.get());
+  *aOutValue = value && *value;
+#else
+  /* For non-Unix/Linux platforms we have to fall back to a
+   * "portable" definition (which is incorrect for Unix/Linux!!!!)
+   * which simply checks whether the string returned by |Get()| is empty
+   * or not.
+   */
+  nsAutoString value;
+  Get(aName, value);
+  *aOutValue = !value.IsEmpty();
+#endif /* XP_UNIX */
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsEnvironment::Get(const nsAString& aName, nsAString& aOutValue)
+{
+  nsAutoCString nativeName;
+  nsresult rv = NS_CopyUnicodeToNative(aName, nativeName);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  nsAutoCString nativeVal;
+  const char* value = PR_GetEnv(nativeName.get());
+  if (value && *value) {
+    rv = NS_CopyNativeToUnicode(nsDependentCString(value), aOutValue);
+  } else {
+    aOutValue.Truncate();
+    rv = NS_OK;
+  }
+
+  return rv;
+}
+
+/* Environment strings must have static duration; We're gonna leak all of this
+ * at shutdown: this is by design, caused how Unix/Linux implement environment
+ * vars.
+ */
+
+typedef nsBaseHashtableET<nsCharPtrHashKey, char*> EnvEntryType;
+typedef nsTHashtable<EnvEntryType> EnvHashType;
+
+static EnvHashType* gEnvHash = nullptr;
+
+static bool
+EnsureEnvHash()
+{
+  if (gEnvHash) {
+    return true;
+  }
+
+  gEnvHash = new EnvHashType;
+  if (!gEnvHash) {
+    return false;
+  }
+
+  return true;
+}
+
+NS_IMETHODIMP
+nsEnvironment::Set(const nsAString& aName, const nsAString& aValue)
+{
+  nsAutoCString nativeName;
+  nsAutoCString nativeVal;
+
+  nsresult rv = NS_CopyUnicodeToNative(aName, nativeName);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  rv = NS_CopyUnicodeToNative(aValue, nativeVal);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  MutexAutoLock lock(mLock);
+
+  if (!EnsureEnvHash()) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  EnvEntryType* entry = gEnvHash->PutEntry(nativeName.get());
+  if (!entry) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  char* newData = PR_smprintf("%s=%s",
+                              nativeName.get(),
+                              nativeVal.get());
+  if (!newData) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  PR_SetEnv(newData);
+  if (entry->mData) {
+    PR_smprintf_free(entry->mData);
+  }
+  entry->mData = newData;
+  return NS_OK;
+}
+
+
diff --git a/xpcom/threads/nsEnvironment.h b/xpcom/threads/nsEnvironment.h
new file mode 100644
index 000000000..234055a07
--- /dev/null
+++ b/xpcom/threads/nsEnvironment.h
@@ -0,0 +1,36 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsEnvironment_h__
+#define nsEnvironment_h__
+
+#include "mozilla/Attributes.h"
+#include "mozilla/Mutex.h"
+#include "nsIEnvironment.h"
+
+#define NS_ENVIRONMENT_CID \
+  { 0X3D68F92UL, 0X9513, 0X4E25, \
+  { 0X9B, 0XE9, 0X7C, 0XB2, 0X39, 0X87, 0X41, 0X72 } }
+#define NS_ENVIRONMENT_CONTRACTID "@mozilla.org/process/environment;1"
+
+class nsEnvironment final : public nsIEnvironment
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIENVIRONMENT
+
+  static nsresult Create(nsISupports* aOuter, REFNSIID aIID, void** aResult);
+
+private:
+  nsEnvironment() : mLock("nsEnvironment.mLock")
+  {
+  }
+  ~nsEnvironment();
+
+  mozilla::Mutex mLock;
+};
+
+#endif /* !nsEnvironment_h__ */
diff --git a/xpcom/threads/nsEventQueue.cpp b/xpcom/threads/nsEventQueue.cpp
new file mode 100644
index 000000000..4ca2f11ea
--- /dev/null
+++ b/xpcom/threads/nsEventQueue.cpp
@@ -0,0 +1,155 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsEventQueue.h"
+#include "nsAutoPtr.h"
+#include "mozilla/Logging.h"
+#include "nsThreadUtils.h"
+#include "prthread.h"
+#include "mozilla/ChaosMode.h"
+
+using namespace mozilla;
+
+static LazyLogModule sEventQueueLog("nsEventQueue");
+#ifdef LOG
+#undef LOG
+#endif
+#define LOG(args) MOZ_LOG(sEventQueueLog, mozilla::LogLevel::Debug, args)
+
+nsEventQueue::nsEventQueue(mozilla::CondVar& aCondVar, EventQueueType aType)
+  : mHead(nullptr)
+  , mTail(nullptr)
+  , mOffsetHead(0)
+  , mOffsetTail(0)
+  , mEventsAvailable(aCondVar)
+  , mType(aType)
+{
+}
+
+nsEventQueue::~nsEventQueue()
+{
+  // It'd be nice to be able to assert that no one else is holding the lock,
+  // but NSPR doesn't really expose APIs for it.
+  NS_ASSERTION(IsEmpty(),
+               "Non-empty event queue being destroyed; events being leaked.");
+
+  if (mHead) {
+    FreePage(mHead);
+  }
+}
+
+bool
+nsEventQueue::GetEvent(bool aMayWait, nsIRunnable** aResult,
+                       MutexAutoLock& aProofOfLock)
+{
+  if (aResult) {
+    *aResult = nullptr;
+  }
+
+  while (IsEmpty()) {
+    if (!aMayWait) {
+      return false;
+    }
+    LOG(("EVENTQ(%p): wait begin\n", this));
+    mEventsAvailable.Wait();
+    LOG(("EVENTQ(%p): wait end\n", this));
+
+    if (mType == eSharedCondVarQueue) {
+      if (IsEmpty()) {
+        return false;
+      }
+      break;
+    }
+  }
+
+  if (aResult) {
+    MOZ_ASSERT(mOffsetHead < EVENTS_PER_PAGE);
+    MOZ_ASSERT_IF(mHead == mTail, mOffsetHead <= mOffsetTail);
+    *aResult = mHead->mEvents[mOffsetHead++];
+
+    MOZ_ASSERT(*aResult);
+    MOZ_ASSERT(mOffsetHead <= EVENTS_PER_PAGE);
+
+    // Check if mHead points to empty Page
+    if (mOffsetHead == EVENTS_PER_PAGE) {
+      Page* dead = mHead;
+      mHead = mHead->mNext;
+      FreePage(dead);
+      mOffsetHead = 0;
+    }
+  }
+
+  return true;
+}
+
+void
+nsEventQueue::PutEvent(already_AddRefed<nsIRunnable>&& aRunnable,
+                       MutexAutoLock& aProofOfLock)
+{
+  if (!mHead) {
+    mHead = NewPage();
+    MOZ_ASSERT(mHead);
+
+    mTail = mHead;
+    mOffsetHead = 0;
+    mOffsetTail = 0;
+  } else if (mOffsetTail == EVENTS_PER_PAGE) {
+    Page* page = NewPage();
+    MOZ_ASSERT(page);
+
+    mTail->mNext = page;
+    mTail = page;
+    mOffsetTail = 0;
+  }
+
+  nsIRunnable*& queueLocation = mTail->mEvents[mOffsetTail];
+  MOZ_ASSERT(!queueLocation);
+  queueLocation = aRunnable.take();
+  ++mOffsetTail;
+  LOG(("EVENTQ(%p): notify\n", this));
+  mEventsAvailable.Notify();
+}
+
+void
+nsEventQueue::PutEvent(nsIRunnable* aRunnable, MutexAutoLock& aProofOfLock)
+{
+  nsCOMPtr<nsIRunnable> event(aRunnable);
+  PutEvent(event.forget(), aProofOfLock);
+}
+
+size_t
+nsEventQueue::Count(MutexAutoLock& aProofOfLock) const
+{
+  // It is obvious count is 0 when the queue is empty.
+  if (!mHead) {
+    return 0;
+  }
+
+  /* How we count the number of events in the queue:
+   * 1. Let pageCount(x, y) denote the number of pages excluding the tail page
+   *    where x is the index of head page and y is the index of the tail page.
+   * 2. Then we have pageCount(x, y) = y - x.
+   *
+   * Ex: pageCount(0, 0) = 0 where both head and tail pages point to page 0.
+   *     pageCount(0, 1) = 1 where head points to page 0 and tail points page 1.
+   *
+   * 3. number of events = (EVENTS_PER_PAGE * pageCount(x, y))
+   *      - (empty slots in head page) + (non-empty slots in tail page)
+   *      = (EVENTS_PER_PAGE * pageCount(x, y)) - mOffsetHead + mOffsetTail
+   */
+
+  int count = -mOffsetHead;
+
+  // Compute (EVENTS_PER_PAGE * pageCount(x, y))
+  for (Page* page = mHead; page != mTail; page = page->mNext) {
+    count += EVENTS_PER_PAGE;
+  }
+
+  count += mOffsetTail;
+  MOZ_ASSERT(count >= 0);
+
+  return count;
+}
diff --git a/xpcom/threads/nsEventQueue.h b/xpcom/threads/nsEventQueue.h
new file mode 100644
index 000000000..23b55e63d
--- /dev/null
+++ b/xpcom/threads/nsEventQueue.h
@@ -0,0 +1,123 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsEventQueue_h__
+#define nsEventQueue_h__
+
+#include <stdlib.h>
+#include "mozilla/CondVar.h"
+#include "mozilla/Mutex.h"
+#include "nsIRunnable.h"
+#include "nsCOMPtr.h"
+#include "mozilla/AlreadyAddRefed.h"
+#include "mozilla/UniquePtr.h"
+
+class nsThreadPool;
+
+// A threadsafe FIFO event queue...
+class nsEventQueue
+{
+public:
+  typedef mozilla::MutexAutoLock MutexAutoLock;
+
+  enum EventQueueType
+  {
+    eNormalQueue,
+    eSharedCondVarQueue
+  };
+
+  nsEventQueue(mozilla::CondVar& aCondVar, EventQueueType aType);
+  ~nsEventQueue();
+
+  // This method adds a new event to the pending event queue.  The queue holds
+  // a strong reference to the event after this method returns.  This method
+  // cannot fail.
+  void PutEvent(nsIRunnable* aEvent, MutexAutoLock& aProofOfLock);
+  void PutEvent(already_AddRefed<nsIRunnable>&& aEvent,
+                MutexAutoLock& aProofOfLock);
+
+  // This method gets an event from the event queue.  If mayWait is true, then
+  // the method will block the calling thread until an event is available.  If
+  // the event is null, then the method returns immediately indicating whether
+  // or not an event is pending.  When the resulting event is non-null, the
+  // caller is responsible for releasing the event object.  This method does
+  // not alter the reference count of the resulting event.
+  bool GetEvent(bool aMayWait, nsIRunnable** aEvent,
+                MutexAutoLock& aProofOfLock);
+
+  // This method returns true if there is a pending event.
+  bool HasPendingEvent(MutexAutoLock& aProofOfLock)
+  {
+    return GetEvent(false, nullptr, aProofOfLock);
+  }
+
+  // This method returns the next pending event or null.
+  bool GetPendingEvent(nsIRunnable** aRunnable, MutexAutoLock& aProofOfLock)
+  {
+    return GetEvent(false, aRunnable, aProofOfLock);
+  }
+
+  size_t Count(MutexAutoLock&) const;
+
+private:
+  bool IsEmpty()
+  {
+    return !mHead || (mHead == mTail && mOffsetHead == mOffsetTail);
+  }
+
+  enum
+  {
+    EVENTS_PER_PAGE = 255
+  };
+
+  // Page objects are linked together to form a simple deque.
+
+  struct Page
+  {
+    struct Page* mNext;
+    nsIRunnable* mEvents[EVENTS_PER_PAGE];
+  };
+
+  static_assert((sizeof(Page) & (sizeof(Page) - 1)) == 0,
+                "sizeof(Page) should be a power of two to avoid heap slop.");
+
+  static Page* NewPage()
+  {
+    return static_cast<Page*>(moz_xcalloc(1, sizeof(Page)));
+  }
+
+  static void FreePage(Page* aPage)
+  {
+    free(aPage);
+  }
+
+  Page* mHead;
+  Page* mTail;
+
+  uint16_t mOffsetHead;  // offset into mHead where next item is removed
+  uint16_t mOffsetTail;  // offset into mTail where next item is added
+  mozilla::CondVar& mEventsAvailable;
+
+  EventQueueType mType;
+
+  // These methods are made available to nsThreadPool as a hack, since
+  // nsThreadPool needs to have its threads sleep for fixed amounts of
+  // time as well as being able to wake up all threads when thread
+  // limits change.
+  friend class nsThreadPool;
+  void Wait(PRIntervalTime aInterval)
+  {
+    MOZ_ASSERT(mType == eNormalQueue);
+    mEventsAvailable.Wait(aInterval);
+  }
+  void NotifyAll()
+  {
+    MOZ_ASSERT(mType == eNormalQueue);
+    mEventsAvailable.NotifyAll();
+  }
+};
+
+#endif  // nsEventQueue_h__
diff --git a/xpcom/threads/nsICancelableRunnable.h b/xpcom/threads/nsICancelableRunnable.h
new file mode 100644
index 000000000..5ae9f5b14
--- /dev/null
+++ b/xpcom/threads/nsICancelableRunnable.h
@@ -0,0 +1,38 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsICancelableRunnable_h__
+#define nsICancelableRunnable_h__
+
+#include "nsISupports.h"
+
+#define NS_ICANCELABLERUNNABLE_IID \
+{ 0xde93dc4c, 0x5eea, 0x4eb7, \
+{ 0xb6, 0xd1, 0xdb, 0xf1, 0xe0, 0xce, 0xf6, 0x5c } }
+
+class nsICancelableRunnable : public nsISupports
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_ICANCELABLERUNNABLE_IID)
+
+  /*
+   * Cancels a pending task.  If the task has already been executed this will
+   * be a no-op.  Calling this method twice is considered an error.
+   *
+   * @throws NS_ERROR_UNEXPECTED
+   *   Indicates that the runnable has already been canceled.
+   */
+  virtual nsresult Cancel() = 0;
+
+protected:
+  nsICancelableRunnable() { }
+  virtual ~nsICancelableRunnable() {}
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsICancelableRunnable,
+                              NS_ICANCELABLERUNNABLE_IID)
+
+#endif // nsICancelableRunnable_h__
diff --git a/xpcom/threads/nsIEnvironment.idl b/xpcom/threads/nsIEnvironment.idl
new file mode 100644
index 000000000..afbc3eb7c
--- /dev/null
+++ b/xpcom/threads/nsIEnvironment.idl
@@ -0,0 +1,55 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * Scriptable access to the current process environment.
+ *
+ */
+[scriptable, uuid(101d5941-d820-4e85-a266-9a3469940807)]
+interface nsIEnvironment : nsISupports
+{
+    /**
+     * Set the value of an environment variable.
+     *
+     * @param aName   the variable name to set.
+     * @param aValue  the value to set.
+     */
+    void set(in AString aName, in AString aValue);
+
+    /**
+     * Get the value of an environment variable.
+     *
+     * @param aName   the variable name to retrieve.
+     * @return        returns the value of the env variable. An empty string
+     *                will be returned when the env variable does not exist or
+     *                when the value itself is an empty string - please use
+     *                |exists()| to probe whether the env variable exists
+     *                or not.
+     */
+    AString get(in AString aName);
+
+    /**
+     * Check the existence of an environment variable.
+     * This method checks whether an environment variable is present in
+     * the environment or not.
+     *
+     * - For Unix/Linux platforms we follow the Unix definition:
+     * An environment variable exists when |getenv()| returns a non-NULL value.
+     * An environment variable does not exist when |getenv()| returns NULL.
+     * - For non-Unix/Linux platforms we have to fall back to a 
+     * "portable" definition (which is incorrect for Unix/Linux!!!!)
+     * which simply checks whether the string returned by |Get()| is empty
+     * or not.
+     *
+     * @param aName   the variable name to probe.
+     * @return        if the variable has been set, the value returned is
+     *                PR_TRUE. If the variable was not defined in the
+     *                environment PR_FALSE will be returned.
+     */
+    boolean exists(in AString aName);
+};
+
diff --git a/xpcom/threads/nsIEventTarget.idl b/xpcom/threads/nsIEventTarget.idl
new file mode 100644
index 000000000..a6f9068dc
--- /dev/null
+++ b/xpcom/threads/nsIEventTarget.idl
@@ -0,0 +1,127 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+#include "nsIRunnable.idl"
+%{C++
+#include "nsCOMPtr.h"
+#include "mozilla/AlreadyAddRefed.h"
+%}
+
+native alreadyAddRefed_nsIRunnable(already_AddRefed<nsIRunnable>);
+
+[scriptable, uuid(88145945-3278-424e-9f37-d874cbdd9f6f)]
+interface nsIEventTarget : nsISupports
+{
+  /* until we can get rid of all uses, keep the non-alreadyAddRefed<> version */
+%{C++
+    nsresult Dispatch(nsIRunnable* aEvent, uint32_t aFlags) {
+      return Dispatch(nsCOMPtr<nsIRunnable>(aEvent).forget(), aFlags);
+    }
+%}
+
+  /**
+   * This flag specifies the default mode of event dispatch, whereby the event
+   * is simply queued for later processing.  When this flag is specified,
+   * dispatch returns immediately after the event is queued.
+   */
+  const unsigned long DISPATCH_NORMAL = 0;
+
+  /**
+   * This flag specifies the synchronous mode of event dispatch, in which the
+   * dispatch method does not return until the event has been processed.
+   *
+   * NOTE: passing this flag to dispatch may have the side-effect of causing
+   * other events on the current thread to be processed while waiting for the
+   * given event to be processed.
+   */
+  const unsigned long DISPATCH_SYNC = 1;
+
+  /**
+   * This flag specifies that the dispatch is occurring from a running event
+   * that was dispatched to the same event target, and that event is about to
+   * finish.
+   *
+   * A thread pool can use this as an optimization hint to not spin up
+   * another thread, since the current thread is about to become idle.
+   *
+   * These events are always async.
+   */
+  const unsigned long DISPATCH_AT_END = 2;
+
+  /**
+   * Check to see if this event target is associated with the current thread.
+   *
+   * @returns
+   *   A boolean value that if "true" indicates that events dispatched to this
+   *   event target will run on the current thread (i.e., the thread calling
+   *   this method).
+   */
+  boolean isOnCurrentThread();
+
+  /**
+   * Dispatch an event to this event target.  This function may be called from
+   * any thread, and it may be called re-entrantly.
+   *
+   * @param event
+   *   The alreadyAddRefed<> event to dispatch.
+   *   NOTE that the event will be leaked if it fails to dispatch.
+   * @param flags
+   *   The flags modifying event dispatch.  The flags are described in detail
+   *   below.
+   *
+   * @throws NS_ERROR_INVALID_ARG
+   *   Indicates that event is null.
+   * @throws NS_ERROR_UNEXPECTED
+   *   Indicates that the thread is shutting down and has finished processing
+   * events, so this event would never run and has not been dispatched.
+   */
+  [noscript, binaryname(Dispatch)] void dispatchFromC(in alreadyAddRefed_nsIRunnable event, in unsigned long flags);
+  /**
+   * Version of Dispatch to expose to JS, which doesn't require an alreadyAddRefed<>
+   * (it will be converted to that internally)
+   *
+   * @param event
+   *   The (raw) event to dispatch.
+   * @param flags
+   *   The flags modifying event dispatch.  The flags are described in detail
+   *   below.
+   *
+   * @throws NS_ERROR_INVALID_ARG
+   *   Indicates that event is null.
+   * @throws NS_ERROR_UNEXPECTED
+   *   Indicates that the thread is shutting down and has finished processing
+   * events, so this event would never run and has not been dispatched.
+   */
+  [binaryname(DispatchFromScript)] void dispatch(in nsIRunnable event, in unsigned long flags);
+  /**
+   * Dispatch an event to this event target, but do not run it before delay
+   * milliseconds have passed.  This function may be called from any thread.
+   *
+   * @param event
+   *   The alreadyAddrefed<> event to dispatch.
+   * @param delay
+   *   The delay (in ms) before running the event.  If event does not rise to
+   *   the top of the event queue before the delay has passed, it will be set
+   *   aside to execute once the delay has passed.  Otherwise, it will be
+   *   executed immediately.
+   *
+   * @throws NS_ERROR_INVALID_ARG
+   *   Indicates that event is null.
+   * @throws NS_ERROR_UNEXPECTED
+   *   Indicates that the thread is shutting down and has finished processing
+   * events, so this event would never run and has not been dispatched, or
+   * that delay is zero.
+   */
+  [noscript] void delayedDispatch(in alreadyAddRefed_nsIRunnable event, in unsigned long delay);
+};
+
+%{C++
+// convenient aliases:
+#define NS_DISPATCH_NORMAL nsIEventTarget::DISPATCH_NORMAL
+#define NS_DISPATCH_SYNC   nsIEventTarget::DISPATCH_SYNC
+#define NS_DISPATCH_AT_END nsIEventTarget::DISPATCH_AT_END
+%}
diff --git a/xpcom/threads/nsIIdlePeriod.idl b/xpcom/threads/nsIIdlePeriod.idl
new file mode 100644
index 000000000..aa72b2171
--- /dev/null
+++ b/xpcom/threads/nsIIdlePeriod.idl
@@ -0,0 +1,32 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+%{C++
+namespace mozilla {
+class TimeStamp;
+}
+%}
+
+native TimeStamp(mozilla::TimeStamp);
+
+/**
+ * An instance implementing nsIIdlePeriod is used by an associated
+ * nsIThread to estimate when it is likely that it will receive an
+ * event.
+ */
+[builtinclass, uuid(21dd35a2-eae9-4bd8-b470-0dfa35a0e3b9)]
+interface nsIIdlePeriod : nsISupports
+{
+    /**
+     * Return an estimate of a point in time in the future when we
+     * think that the associated thread will become busy. Should
+     * return TimeStamp() (i.e. the null time) or a time less than
+     * TimeStamp::Now() if the thread is currently busy or will become
+     * busy very soon.
+     */
+    TimeStamp getIdlePeriodHint();
+};
diff --git a/xpcom/threads/nsIIncrementalRunnable.h b/xpcom/threads/nsIIncrementalRunnable.h
new file mode 100644
index 000000000..526bc165e
--- /dev/null
+++ b/xpcom/threads/nsIIncrementalRunnable.h
@@ -0,0 +1,41 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsIIncrementalRunnable_h__
+#define nsIIncrementalRunnable_h__
+
+#include "nsISupports.h"
+#include "mozilla/TimeStamp.h"
+
+#define NS_IINCREMENTALRUNNABLE_IID \
+{ 0x688be92e, 0x7ade, 0x4fdc, \
+{ 0x9d, 0x83, 0x74, 0xcb, 0xef, 0xf4, 0xa5, 0x2c } }
+
+
+/**
+ * A task interface for tasks that can schedule their work to happen
+ * in increments bounded by a deadline.
+ */
+class nsIIncrementalRunnable : public nsISupports
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_IINCREMENTALRUNNABLE_IID)
+
+  /**
+   * Notify the task of a point in time in the future when the task
+   * should stop executing.
+   */
+  virtual void SetDeadline(mozilla::TimeStamp aDeadline) = 0;
+
+protected:
+  nsIIncrementalRunnable() { }
+  virtual ~nsIIncrementalRunnable() {}
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsIIncrementalRunnable,
+                              NS_IINCREMENTALRUNNABLE_IID)
+
+#endif // nsIIncrementalRunnable_h__
diff --git a/xpcom/threads/nsIProcess.idl b/xpcom/threads/nsIProcess.idl
new file mode 100644
index 000000000..2c7dcd55e
--- /dev/null
+++ b/xpcom/threads/nsIProcess.idl
@@ -0,0 +1,99 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIFile;
+interface nsIObserver;
+
+[scriptable, uuid(609610de-9954-4a63-8a7c-346350a86403)]
+interface nsIProcess : nsISupports
+{
+  /**
+   * Initialises the process with an executable to be run. Call the run method
+   * to run the executable.
+   * @param executable The executable to run.
+   */
+  void init(in nsIFile executable);
+
+  /**
+   * Kills the running process. After exiting the process will either have
+   * been killed or a failure will have been returned.
+   */
+  void kill();
+
+  /**
+   * Executes the file this object was initialized with
+   * @param blocking   Whether to wait until the process terminates before
+                       returning or not.
+   * @param args       An array of arguments to pass to the process in the
+   *                   native character set.
+   * @param count      The length of the args array.
+   */
+  void run(in boolean blocking, [array, size_is(count)] in string args,
+           in unsigned long count);
+
+  /**
+   * Executes the file this object was initialized with optionally calling
+   * an observer after the process has finished running.
+   * @param args       An array of arguments to pass to the process in the
+   *                   native character set.
+   * @param count      The length of the args array.
+   * @param observer   An observer to notify when the process has completed. It
+   *                   will receive this process instance as the subject and
+   *                   "process-finished" or "process-failed" as the topic. The
+   *                   observer will be notified on the main thread.
+   * @param holdWeak   Whether to use a weak reference to hold the observer.
+   */
+  void runAsync([array, size_is(count)] in string args, in unsigned long count,
+                [optional] in nsIObserver observer, [optional] in boolean holdWeak);
+
+  /**
+   * Executes the file this object was initialized with
+   * @param blocking   Whether to wait until the process terminates before
+                       returning or not.
+   * @param args       An array of arguments to pass to the process in UTF-16
+   * @param count      The length of the args array.
+   */
+  void runw(in boolean blocking, [array, size_is(count)] in wstring args,
+	    in unsigned long count);
+
+  /**
+   * Executes the file this object was initialized with optionally calling
+   * an observer after the process has finished running.
+   * @param args       An array of arguments to pass to the process in UTF-16
+   * @param count      The length of the args array.
+   * @param observer   An observer to notify when the process has completed. It
+   *                   will receive this process instance as the subject and
+   *                   "process-finished" or "process-failed" as the topic. The
+   *                   observer will be notified on the main thread.
+   * @param holdWeak   Whether to use a weak reference to hold the observer.
+   */
+  void runwAsync([array, size_is(count)] in wstring args,
+		 in unsigned long count,
+		 [optional] in nsIObserver observer, [optional] in boolean holdWeak);
+
+  /**
+   * The process identifier of the currently running process. This will only
+   * be available after the process has started and may not be available on
+   * some platforms.
+   */
+  readonly attribute unsigned long pid;
+
+  /**
+   * The exit value of the process. This is only valid after the process has
+   * exited.
+   */
+  readonly attribute long exitValue;
+
+  /**
+   * Returns whether the process is currently running or not.
+   */
+  readonly attribute boolean isRunning;
+};
+
+%{C++
+
+#define NS_PROCESS_CONTRACTID "@mozilla.org/process/util;1"
+%}
diff --git a/xpcom/threads/nsIRunnable.idl b/xpcom/threads/nsIRunnable.idl
new file mode 100644
index 000000000..4d26f72d9
--- /dev/null
+++ b/xpcom/threads/nsIRunnable.idl
@@ -0,0 +1,27 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * Represents a task which can be dispatched to a thread for execution.
+ */
+
+[scriptable, function, uuid(4a2abaf0-6886-11d3-9382-00104ba0fd40)]
+interface nsIRunnable : nsISupports
+{
+    /**
+     * The function implementing the task to be run.
+     */
+    void run();
+};
+
+[uuid(e75aa42a-80a9-11e6-afb5-e89d87348e2c)]
+interface nsIRunnablePriority : nsISupports
+{
+    const unsigned short PRIORITY_NORMAL = 0;
+    const unsigned short PRIORITY_HIGH = 1;
+    readonly attribute unsigned long priority;
+};
diff --git a/xpcom/threads/nsISupportsPriority.idl b/xpcom/threads/nsISupportsPriority.idl
new file mode 100644
index 000000000..579c280cf
--- /dev/null
+++ b/xpcom/threads/nsISupportsPriority.idl
@@ -0,0 +1,45 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * This interface exposes the general notion of a scheduled object with a
+ * integral priority value.  Following UNIX conventions, smaller (and possibly
+ * negative) values have higher priority.
+ *
+ * This interface does not strictly define what happens when the priority of an
+ * object is changed.  An implementation of this interface is free to define
+ * the side-effects of changing the priority of an object.  In some cases,
+ * changing the priority of an object may be disallowed (resulting in an
+ * exception being thrown) or may simply be ignored.
+ */
+[scriptable, uuid(aa578b44-abd5-4c19-8b14-36d4de6fdc36)]
+interface nsISupportsPriority : nsISupports
+{
+  /**
+   * Typical priority values.
+   */
+  const long PRIORITY_HIGHEST = -20;
+  const long PRIORITY_HIGH    = -10;
+  const long PRIORITY_NORMAL  =   0;
+  const long PRIORITY_LOW     =  10;
+  const long PRIORITY_LOWEST  =  20;
+  
+  /**
+   * This attribute may be modified to change the priority of this object.  The
+   * implementation of this interface is free to truncate a given priority
+   * value to whatever limits are appropriate.  Typically, this attribute is
+   * initialized to PRIORITY_NORMAL, but implementations may choose to assign a
+   * different initial value.
+   */
+  attribute long priority;
+
+  /**
+   * This method adjusts the priority attribute by a given delta.  It helps
+   * reduce the amount of coding required to increment or decrement the value
+   * of the priority attribute.
+   */
+  void adjustPriority(in long delta);
+};
diff --git a/xpcom/threads/nsIThread.idl b/xpcom/threads/nsIThread.idl
new file mode 100644
index 000000000..fbfc8d4fb
--- /dev/null
+++ b/xpcom/threads/nsIThread.idl
@@ -0,0 +1,149 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIEventTarget.idl"
+#include "nsIIdlePeriod.idl"
+
+%{C++
+#include "mozilla/AlreadyAddRefed.h"
+%}
+
+[ptr] native PRThread(PRThread);
+
+native alreadyAddRefed_nsIIdlePeriod(already_AddRefed<nsIIdlePeriod>);
+
+/**
+ * This interface provides a high-level abstraction for an operating system
+ * thread.
+ *
+ * Threads have a built-in event queue, and a thread is an event target that
+ * can receive nsIRunnable objects (events) to be processed on the thread.
+ *
+ * See nsIThreadManager for the API used to create and locate threads.
+ */
+[scriptable, uuid(5801d193-29d1-4964-a6b7-70eb697ddf2b)]
+interface nsIThread : nsIEventTarget
+{
+  /**
+   * @returns
+   *   The NSPR thread object corresponding to this nsIThread.
+   */
+  [noscript] readonly attribute PRThread PRThread;
+
+  /**
+   * @returns
+   *  Whether or not this thread may call into JS. Used in the profiler
+   *  to avoid some unnecessary locking.
+   */
+  [noscript] attribute boolean CanInvokeJS;
+
+
+  /**
+   * Shutdown the thread.  This method prevents further dispatch of events to
+   * the thread, and it causes any pending events to run to completion before
+   * the thread joins (see PR_JoinThread) with the current thread.  During this
+   * method call, events for the current thread may be processed.
+   *
+   * This method MAY NOT be executed from the thread itself.  Instead, it is
+   * meant to be executed from another thread (usually the thread that created
+   * this thread or the main application thread).  When this function returns,
+   * the thread will be shutdown, and it will no longer be possible to dispatch
+   * events to the thread.
+   *
+   * @throws NS_ERROR_UNEXPECTED
+   *   Indicates that this method was erroneously called when this thread was
+   *   the current thread, that this thread was not created with a call to
+   *   nsIThreadManager::NewThread, or if this method was called more than once
+   *   on the thread object.
+   */
+  void shutdown();
+
+  /**
+   * This method may be called to determine if there are any events ready to be
+   * processed.  It may only be called when this thread is the current thread.
+   *
+   * Because events may be added to this thread by another thread, a "false"
+   * result does not mean that this thread has no pending events.  It only
+   * means that there were no pending events when this method was called.
+   *
+   * @returns
+   *   A boolean value that if "true" indicates that this thread has one or
+   *   more pending events.
+   *
+   * @throws NS_ERROR_UNEXPECTED
+   *   Indicates that this method was erroneously called when this thread was
+   *   not the current thread.
+   */
+  boolean hasPendingEvents();
+
+  /**
+   * Process the next event.  If there are no pending events, then this method
+   * may wait -- depending on the value of the mayWait parameter -- until an
+   * event is dispatched to this thread.  This method is re-entrant but may
+   * only be called if this thread is the current thread.
+   *
+   * @param mayWait
+   *   A boolean parameter that if "true" indicates that the method may block
+   *   the calling thread to wait for a pending event.
+   *
+   * @returns
+   *   A boolean value that if "true" indicates that an event was processed.
+   *
+   * @throws NS_ERROR_UNEXPECTED
+   *   Indicates that this method was erroneously called when this thread was
+   *   not the current thread.
+   */
+  boolean processNextEvent(in boolean mayWait);
+
+  /**
+   * Shutdown the thread asynchronously.  This method immediately prevents
+   * further dispatch of events to the thread, and it causes any pending events
+   * to run to completion before this thread joins with the current thread.
+   *
+   * UNLIKE shutdown() this does not process events on the current thread.
+   * Instead it merely ensures that the current thread continues running until
+   * this thread has shut down.
+   *
+   * This method MAY NOT be executed from the thread itself.  Instead, it is
+   * meant to be executed from another thread (usually the thread that created
+   * this thread or the main application thread).  When this function returns,
+   * the thread will continue running until it exhausts its event queue.
+   *
+   * @throws NS_ERROR_UNEXPECTED
+   *   Indicates that this method was erroneously called when this thread was
+   *   the current thread, that this thread was not created with a call to
+   *   nsIThreadManager::NewThread, or if this method was called more than once
+   *   on the thread object.
+   */
+  void asyncShutdown();
+
+  /**
+   * Register an instance of nsIIdlePeriod which works as a facade of
+   * the abstract notion of a "current idle period". The
+   * nsIIdlePeriod should always represent the "current" idle period
+   * with regard to expected work for the thread. The thread is free
+   * to use this when there are no higher prioritized tasks to process
+   * to determine if it is reasonable to schedule tasks that could run
+   * when the thread is idle. The responsibility of the registered
+   * nsIIdlePeriod is to answer with an estimated deadline at which
+   * the thread should expect that it could receive new higher
+   * priority tasks.
+   */
+  [noscript] void registerIdlePeriod(in alreadyAddRefed_nsIIdlePeriod aIdlePeriod);
+
+  /**
+   * Dispatch an event to the thread's idle queue.  This function may be called
+   * from any thread, and it may be called re-entrantly.
+   *
+   * @param event
+   *   The alreadyAddRefed<> event to dispatch.
+   *   NOTE that the event will be leaked if it fails to dispatch.
+   *
+   * @throws NS_ERROR_INVALID_ARG
+   *   Indicates that event is null.
+   */
+  [noscript] void idleDispatch(in alreadyAddRefed_nsIRunnable event);
+};
diff --git a/xpcom/threads/nsIThreadInternal.idl b/xpcom/threads/nsIThreadInternal.idl
new file mode 100644
index 000000000..e5d7cc83f
--- /dev/null
+++ b/xpcom/threads/nsIThreadInternal.idl
@@ -0,0 +1,135 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIThread.idl"
+
+interface nsIRunnable;
+interface nsIThreadObserver;
+
+/**
+ * The XPCOM thread object implements this interface, which allows a consumer
+ * to observe dispatch activity on the thread.
+ */
+[scriptable, uuid(a3a72e5f-71d9-4add-8f30-59a78fb6d5eb)]
+interface nsIThreadInternal : nsIThread
+{
+  /**
+   * Get/set the current thread observer (may be null).  This attribute may be
+   * read from any thread, but must only be set on the thread corresponding to
+   * this thread object.  The observer will be released on the thread
+   * corresponding to this thread object after all other events have been
+   * processed during a call to Shutdown.
+   */
+  attribute nsIThreadObserver observer;
+
+  /**
+   * Add an observer that will *only* receive onProcessNextEvent,
+   * beforeProcessNextEvent. and afterProcessNextEvent callbacks. Always called
+   * on the target thread, and the implementation does not have to be
+   * threadsafe. Order of callbacks is not guaranteed (i.e.
+   * afterProcessNextEvent may be called first depending on whether or not the
+   * observer is added in a nested loop). Holds a strong ref.
+   */
+  void addObserver(in nsIThreadObserver observer);
+
+  /**
+   * Remove an observer added via the addObserver call. Once removed the
+   * observer will never be called again by the thread.
+   */
+  void removeObserver(in nsIThreadObserver observer);
+
+  /**
+   * This method causes any events currently enqueued on the thread to be
+   * suppressed until PopEventQueue is called, and any event dispatched to this
+   * thread's nsIEventTarget will queue as well. Calls to PushEventQueue may be
+   * nested and must each be paired with a call to PopEventQueue in order to
+   * restore the original state of the thread. The returned nsIEventTarget may
+   * be used to push events onto the nested queue. Dispatching will be disabled
+   * once the event queue is popped. The thread will only ever process pending
+   * events for the innermost event queue. Must only be called on the target
+   * thread.
+   */
+  [noscript] nsIEventTarget pushEventQueue();
+
+  /**
+   * Revert a call to PushEventQueue. When an event queue is popped, any events
+   * remaining in the queue are appended to the elder queue. This also causes
+   * the nsIEventTarget returned from PushEventQueue to stop dispatching events.
+   * Must only be called on the target thread, and with the innermost event
+   * queue.
+   */
+  [noscript] void popEventQueue(in nsIEventTarget aInnermostTarget);
+};
+
+/**
+ * This interface provides the observer with hooks to implement a layered
+ * event queue.  For example, it is possible to overlay processing events
+ * for a GUI toolkit on top of the events for a thread:
+ *
+ *   var NativeQueue;
+ *   Observer = {
+ *     onDispatchedEvent(thread) {
+ *       NativeQueue.signal();
+ *     }
+ *     onProcessNextEvent(thread, mayWait) {
+ *       if (NativeQueue.hasNextEvent())
+ *         NativeQueue.processNextEvent();
+ *       while (mayWait && !thread.hasPendingEvent()) {
+ *         NativeQueue.wait();
+ *         NativeQueue.processNextEvent();
+ *       }
+ *     }
+ *   };
+ *
+ * NOTE: The implementation of this interface must be threadsafe.
+ * 
+ * NOTE: It is valid to change the thread's observer during a call to an
+ *       observer method.
+ *
+ * NOTE: Will be split into two interfaces soon: one for onProcessNextEvent and
+ *       afterProcessNextEvent, then another that inherits the first and adds
+ *       onDispatchedEvent.
+ */
+[uuid(cc8da053-1776-44c2-9199-b5a629d0a19d)]
+interface nsIThreadObserver : nsISupports
+{
+  /**
+   * This method is called after an event has been dispatched to the thread.
+   * This method may be called from any thread. 
+   *
+   * @param thread
+   *   The thread where the event is being dispatched.
+   */
+  void onDispatchedEvent(in nsIThreadInternal thread);
+
+  /**
+   * This method is called when nsIThread::ProcessNextEvent is called.  It does
+   * not guarantee that an event is actually going to be processed.  This method
+   * is only called on the target thread.
+   *
+   * @param thread
+   *   The thread being asked to process another event.
+   * @param mayWait
+   *   Indicates whether or not the method is allowed to block the calling
+   *   thread.  For example, this parameter is false during thread shutdown.
+   */
+  void onProcessNextEvent(in nsIThreadInternal thread, in boolean mayWait);
+
+  /**
+   * This method is called (from nsIThread::ProcessNextEvent) after an event
+   * is processed.  It does not guarantee that an event was actually processed
+   * (depends on the value of |eventWasProcessed|.  This method is only called
+   * on the target thread.  DO NOT EVER RUN SCRIPT FROM THIS CALLBACK!!!
+   *
+   * @param thread
+   *   The thread that processed another event.
+   * @param eventWasProcessed
+   *   Indicates whether an event was actually processed. May be false if the
+   *   |mayWait| flag was false when calling nsIThread::ProcessNextEvent().
+   */
+  void afterProcessNextEvent(in nsIThreadInternal thread,
+                             in bool eventWasProcessed);
+};
diff --git a/xpcom/threads/nsIThreadManager.idl b/xpcom/threads/nsIThreadManager.idl
new file mode 100644
index 000000000..9b4fc126f
--- /dev/null
+++ b/xpcom/threads/nsIThreadManager.idl
@@ -0,0 +1,68 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+[ptr] native PRThread(PRThread);
+
+interface nsIThread;
+
+/**
+ * An interface for creating and locating nsIThread instances.
+ */
+[scriptable, uuid(1be89eca-e2f7-453b-8d38-c11ba247f6f3)]
+interface nsIThreadManager : nsISupports
+{
+  /**
+   * Default number of bytes reserved for a thread's stack, if no stack size
+   * is specified in newThread(). 0 means use platform default.
+   */
+  const unsigned long DEFAULT_STACK_SIZE = 0;
+
+  /**
+   * Create a new thread (a global, user PRThread).
+   *
+   * @param creationFlags
+   *   Reserved for future use.  Pass 0.
+   * @param stackSize
+   *   Number of bytes to reserve for the thread's stack.
+   *
+   * @returns
+   *   The newly created nsIThread object.
+   */
+  nsIThread newThread(in unsigned long creationFlags, [optional] in unsigned long stackSize);
+
+  /**
+   * Get the nsIThread object (if any) corresponding to the given PRThread.
+   * This method returns null if there is no corresponding nsIThread.
+   *
+   * @param prthread
+   *   The PRThread of the nsIThread being requested.
+   *
+   * @returns
+   *   The nsIThread object corresponding to the given PRThread or null if no
+   *   such nsIThread exists.
+   */
+  [noscript] nsIThread getThreadFromPRThread(in PRThread prthread);
+
+  /**
+   * Get the main thread.
+   */
+  readonly attribute nsIThread mainThread;
+
+  /**
+   * Get the current thread.  If the calling thread does not already have a
+   * nsIThread associated with it, then a new nsIThread will be created and
+   * associated with the current PRThread.
+   */
+  readonly attribute nsIThread currentThread;
+
+  /**
+   * This attribute is true if the calling thread is the main thread of the
+   * application process.
+   */
+  readonly attribute boolean isMainThread;
+};
diff --git a/xpcom/threads/nsIThreadPool.idl b/xpcom/threads/nsIThreadPool.idl
new file mode 100644
index 000000000..d04e8504a
--- /dev/null
+++ b/xpcom/threads/nsIThreadPool.idl
@@ -0,0 +1,88 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIEventTarget.idl"
+
+[scriptable, uuid(ef194cab-3f86-4b61-b132-e5e96a79e5d1)]
+interface nsIThreadPoolListener : nsISupports
+{
+  /**
+   * Called when a new thread is created by the thread pool. The notification
+   * happens on the newly-created thread.
+   */
+  void onThreadCreated();
+
+  /**
+   * Called when a thread is about to be destroyed by the thread pool. The
+   * notification happens on the thread that is about to be destroyed.
+   */
+  void onThreadShuttingDown();
+};
+
+/**
+ * An interface to a thread pool.  A thread pool creates a limited number of
+ * anonymous (unnamed) worker threads.  An event dispatched to the thread pool
+ * will be run on the next available worker thread.
+ */
+[scriptable, uuid(76ce99c9-8e43-489a-9789-f27cc4424965)]
+interface nsIThreadPool : nsIEventTarget
+{
+  /**
+   * Shutdown the thread pool.  This method may not be executed from any thread
+   * in the thread pool.  Instead, it is meant to be executed from another
+   * thread (usually the thread that created this thread pool).  When this
+   * function returns, the thread pool and all of its threads will be shutdown,
+   * and it will no longer be possible to dispatch tasks to the thread pool.
+   *
+   * As a side effect, events on the current thread will be processed.
+   */
+  void shutdown();
+
+  /**
+   * Get/set the maximum number of threads allowed at one time in this pool.
+   */
+  attribute unsigned long threadLimit;
+
+  /**
+   * Get/set the maximum number of idle threads kept alive.
+   */
+  attribute unsigned long idleThreadLimit;
+
+  /**
+   * Get/set the amount of time in milliseconds before an idle thread is
+   * destroyed.
+   */
+  attribute unsigned long idleThreadTimeout;
+
+  /**
+   * Get/set the number of bytes reserved for the stack of all threads in
+   * the pool. By default this is nsIThreadManager::DEFAULT_STACK_SIZE.
+   */
+  attribute unsigned long threadStackSize;
+
+  /**
+   * An optional listener that will be notified when a thread is created or
+   * destroyed in the course of the thread pool's operation.
+   *
+   * A listener will only receive notifications about threads created after the
+   * listener is set so it is recommended that the consumer set the listener
+   * before dispatching the first event. A listener that receives an
+   * onThreadCreated() notification is guaranteed to always receive the
+   * corresponding onThreadShuttingDown() notification.
+   *
+   * The thread pool takes ownership of the listener and releases it when the
+   * shutdown() method is called. Threads created after the listener is set will
+   * also take ownership of the listener so that the listener will be kept alive
+   * long enough to receive the guaranteed onThreadShuttingDown() notification.
+   */
+  attribute nsIThreadPoolListener listener;
+
+  /**
+   * Set the label for threads in the pool. All threads will be named
+   * "<aName> #<n>", where <n> is a serial number.
+   */
+  void setName(in ACString aName);
+};
diff --git a/xpcom/threads/nsITimer.idl b/xpcom/threads/nsITimer.idl
new file mode 100644
index 000000000..ade2168f2
--- /dev/null
+++ b/xpcom/threads/nsITimer.idl
@@ -0,0 +1,244 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIObserver;
+interface nsIEventTarget;
+
+%{C++
+#include "mozilla/MemoryReporting.h"
+
+/**
+ * The signature of the timer callback function passed to initWithFuncCallback.
+ * This is the function that will get called when the timer expires if the
+ * timer is initialized via initWithFuncCallback.
+ *
+ * @param aTimer the timer which has expired
+ * @param aClosure opaque parameter passed to initWithFuncCallback
+ */
+class nsITimer;
+typedef void (*nsTimerCallbackFunc) (nsITimer *aTimer, void *aClosure);
+
+/**
+ * The signature of the timer name callback function passed to
+ * initWithNameableFuncCallback.
+ * This is the function that will get called when timer profiling is enabled
+ * via the "TimerFirings" log module.
+ *
+ * @param aTimer the timer which has expired
+ * @param aClosure opaque parameter passed to initWithFuncCallback
+ * @param aBuf a buffer in which to put the name
+ * @param aLen the length of the buffer
+ */
+typedef void (*nsTimerNameCallbackFunc) (nsITimer *aTimer, void *aClosure,
+                                         char *aBuf, size_t aLen);
+%}
+
+native nsTimerCallbackFunc(nsTimerCallbackFunc);
+native nsTimerNameCallbackFunc(nsTimerNameCallbackFunc);
+
+/**
+ * The callback interface for timers.
+ */
+interface nsITimer;
+
+[function, scriptable, uuid(a796816d-7d47-4348-9ab8-c7aeb3216a7d)]
+interface nsITimerCallback : nsISupports
+{
+  /**
+   * @param aTimer the timer which has expired
+   */
+  void notify(in nsITimer timer);
+};
+
+%{C++
+// Two timer deadlines must differ by less than half the PRIntervalTime domain.
+#define DELAY_INTERVAL_LIMIT    PR_BIT(8 * sizeof(PRIntervalTime) - 1)
+%}
+
+/**
+ * nsITimer instances must be initialized by calling one of the "init" methods
+ * documented below.  You may also re-initialize (using one of the init()
+ * methods) an existing instance to avoid the overhead of destroying and
+ * creating a timer.  It is not necessary to cancel the timer in that case.
+ *
+ * By default a timer will fire on the thread that created it.  Set the .target
+ * attribute to fire on a different thread.  Once you have set a timer's .target
+ * and called one of its init functions, any further interactions with the timer
+ * (calling cancel(), changing member fields, etc) should only be done by the
+ * target thread, or races may occur with bad results like timers firing after
+ * they've been canceled, and/or not firing after re-initiatization.
+ */
+[scriptable, uuid(3de4b105-363c-482c-a409-baac83a01bfc)]
+interface nsITimer : nsISupports
+{
+  /* Timer types */
+
+  /**
+   * Type of a timer that fires once only.
+   */
+  const short TYPE_ONE_SHOT = 0;
+
+  /**
+   * After firing, a TYPE_REPEATING_SLACK timer is stopped and not restarted
+   * until its callback completes.  Specified timer period will be at least
+   * the time between when processing for last firing the callback completes
+   * and when the next firing occurs.
+   *
+   * This is the preferable repeating type for most situations.
+   */
+  const short TYPE_REPEATING_SLACK = 1;
+
+  /**
+   * TYPE_REPEATING_PRECISE is just a synonym for
+   * TYPE_REPEATING_PRECISE_CAN_SKIP. They used to be distinct, but the old
+   * TYPE_REPEATING_PRECISE kind was similar to TYPE_REPEATING_PRECISE_CAN_SKIP
+   * while also being less useful. So the distinction was removed.
+   */
+  const short TYPE_REPEATING_PRECISE = 2;
+
+  /**
+   * A TYPE_REPEATING_PRECISE_CAN_SKIP repeating timer aims to have constant
+   * period between firings.  The processing time for each timer callback
+   * should not influence the timer period.  However this timer type
+   * guarantees that it will not queue up new events to fire the callback
+   * until the previous callback event finishes firing.  If the callback
+   * takes a long time, then the next callback will be scheduled immediately
+   * afterward, but only once.  This is the only non-slack timer available.
+   */
+  const short TYPE_REPEATING_PRECISE_CAN_SKIP = 3;
+
+  /**
+   * Initialize a timer that will fire after the said delay.
+   * A user must keep a reference to this timer till it is
+   * is no longer needed or has been cancelled.
+   *
+   * @param aObserver   the callback object that observes the
+   *                    ``timer-callback'' topic with the subject being
+   *                    the timer itself when the timer fires:
+   *
+   *                    observe(nsISupports aSubject, => nsITimer
+   *                            string aTopic,        => ``timer-callback''
+   *                            wstring data          =>  null
+   *
+   * @param aDelay      delay in milliseconds for timer to fire
+   * @param aType       timer type per TYPE* consts defined above
+   */
+  void init(in nsIObserver aObserver, in unsigned long aDelay,
+            in unsigned long aType);
+
+
+  /**
+   * Initialize a timer to fire after the given millisecond interval.
+   * This version takes a function to call and a closure to pass to
+   * that function.
+   *
+   * @param aFunc      The function to invoke
+   * @param aClosure   An opaque pointer to pass to that function
+   * @param aDelay     The millisecond interval
+   * @param aType      Timer type per TYPE* consts defined above
+   */
+  [noscript] void initWithFuncCallback(in nsTimerCallbackFunc aCallback,
+                                       in voidPtr aClosure,
+                                       in unsigned long aDelay,
+                                       in unsigned long aType);
+
+  /**
+   * Initialize a timer to fire after the given millisecond interval.
+   * This version takes a function to call.
+   *
+   * @param aFunc      nsITimerCallback interface to call when timer expires
+   * @param aDelay     The millisecond interval
+   * @param aType      Timer type per TYPE* consts defined above
+   */
+  void initWithCallback(in nsITimerCallback aCallback,
+                        in unsigned long aDelay,
+                        in unsigned long aType);
+
+  /**
+   * Cancel the timer.  This method works on all types, not just on repeating
+   * timers -- you might want to cancel a TYPE_ONE_SHOT timer, and even reuse
+   * it by re-initializing it (to avoid object destruction and creation costs
+   * by conserving one timer instance).
+   */
+  void cancel();
+
+  /**
+   * Like initWithFuncCallback, but also takes a name for the timer; the name
+   * will be used when timer profiling is enabled via the "TimerFirings" log
+   * module.
+   *
+   * @param aFunc      The function to invoke
+   * @param aClosure   An opaque pointer to pass to that function
+   * @param aDelay     The millisecond interval
+   * @param aType      Timer type per TYPE* consts defined above
+   * @param aName      The timer's name
+   */
+  [noscript] void initWithNamedFuncCallback(in nsTimerCallbackFunc aCallback,
+                                            in voidPtr aClosure,
+                                            in unsigned long aDelay,
+                                            in unsigned long aType,
+                                            in string aName);
+
+  /**
+   * Like initWithNamedFuncCallback, but instead of a timer name it takes a
+   * callback that will provide a name when the timer fires.
+   *
+   * @param aFunc      The function to invoke
+   * @param aClosure   An opaque pointer to pass to that function
+   * @param aDelay     The millisecond interval
+   * @param aType      Timer type per TYPE* consts defined above
+   * @param aNameCallback  The callback function
+   */
+  [noscript] void initWithNameableFuncCallback(
+                    in nsTimerCallbackFunc aCallback,
+                    in voidPtr aClosure,
+                    in unsigned long aDelay,
+                    in unsigned long aType,
+                    in nsTimerNameCallbackFunc aNameCallback);
+
+  /**
+   * The millisecond delay of the timeout.
+   *
+   * NOTE: Re-setting the delay on a one-shot timer that has already fired
+   * doesn't restart the timer. Call one of the init() methods to restart
+   * a one-shot timer.
+   */
+  attribute unsigned long delay;
+
+  /**
+   * The timer type - one of the above TYPE_* constants.
+   */
+  attribute unsigned long type;
+
+  /**
+   * The opaque pointer pass to initWithFuncCallback.
+   */
+  [noscript] readonly attribute voidPtr closure;
+
+  /**
+   * The nsITimerCallback object passed to initWithCallback.
+   */
+  readonly attribute nsITimerCallback callback;
+
+  /**
+   * The nsIEventTarget where the callback will be dispatched. Note that this
+   * target may only be set before the call to one of the init methods above.
+   *
+   * By default the target is the thread that created the timer.
+   */
+  attribute nsIEventTarget target;
+
+%{C++
+  virtual size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const = 0;
+%}
+};
+
+%{C++
+#define NS_TIMER_CONTRACTID "@mozilla.org/timer;1"
+#define NS_TIMER_CALLBACK_TOPIC "timer-callback"
+%}
+
diff --git a/xpcom/threads/nsMemoryPressure.cpp b/xpcom/threads/nsMemoryPressure.cpp
new file mode 100644
index 000000000..fea9b0437
--- /dev/null
+++ b/xpcom/threads/nsMemoryPressure.cpp
@@ -0,0 +1,54 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsMemoryPressure.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Atomics.h"
+
+#include "nsThreadUtils.h"
+
+using namespace mozilla;
+
+static Atomic<int32_t, Relaxed> sMemoryPressurePending;
+static_assert(MemPressure_None == 0,
+              "Bad static initialization with the default constructor.");
+
+MemoryPressureState
+NS_GetPendingMemoryPressure()
+{
+  int32_t value = sMemoryPressurePending.exchange(MemPressure_None);
+  return MemoryPressureState(value);
+}
+
+void
+NS_DispatchEventualMemoryPressure(MemoryPressureState aState)
+{
+  /*
+   * A new memory pressure event erases an ongoing memory pressure, but an
+   * existing "new" memory pressure event takes precedence over a new "ongoing"
+   * memory pressure event.
+   */
+  switch (aState) {
+    case MemPressure_None:
+      sMemoryPressurePending = MemPressure_None;
+      break;
+    case MemPressure_New:
+      sMemoryPressurePending = MemPressure_New;
+      break;
+    case MemPressure_Ongoing:
+      sMemoryPressurePending.compareExchange(MemPressure_None,
+                                             MemPressure_Ongoing);
+      break;
+  }
+}
+
+nsresult
+NS_DispatchMemoryPressure(MemoryPressureState aState)
+{
+  NS_DispatchEventualMemoryPressure(aState);
+  nsCOMPtr<nsIRunnable> event = new Runnable;
+  return NS_DispatchToMainThread(event);
+}
diff --git a/xpcom/threads/nsMemoryPressure.h b/xpcom/threads/nsMemoryPressure.h
new file mode 100644
index 000000000..a05728c61
--- /dev/null
+++ b/xpcom/threads/nsMemoryPressure.h
@@ -0,0 +1,77 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMemoryPressure_h__
+#define nsMemoryPressure_h__
+
+#include "nscore.h"
+
+enum MemoryPressureState
+{
+  /*
+   * No memory pressure.
+   */
+  MemPressure_None = 0,
+
+  /*
+   * New memory pressure deteced.
+   *
+   * On a new memory pressure, we stop everything to start cleaning
+   * aggresively the memory used, in order to free as much memory as
+   * possible.
+   */
+  MemPressure_New,
+
+  /*
+   * Repeated memory pressure.
+   *
+   * A repeated memory pressure implies to clean softly recent allocations.
+   * It is supposed to happen after a new memory pressure which already
+   * cleaned aggressivley.  So there is no need to damage the reactivity of
+   * Gecko by stopping the world again.
+   *
+   * In case of conflict with an new memory pressue, the new memory pressure
+   * takes precedence over an ongoing memory pressure.  The reason being
+   * that if no events are processed between 2 notifications (new followed
+   * by ongoing, or ongoing followed by a new) we want to be as aggresive as
+   * possible on the clean-up of the memory.  After all, we are trying to
+   * keep Gecko alive as long as possible.
+   */
+  MemPressure_Ongoing
+};
+
+/**
+ * Return and erase the latest state of the memory pressure event set by any of
+ * the corresponding dispatch function.
+ */
+MemoryPressureState
+NS_GetPendingMemoryPressure();
+
+/**
+ * This function causes the main thread to fire a memory pressure event
+ * before processing the next event, but if there are no events pending in
+ * the main thread's event queue, the memory pressure event would not be
+ * dispatched until one is enqueued. It is infallible and does not allocate
+ * any memory.
+ *
+ * You may call this function from any thread.
+ */
+void
+NS_DispatchEventualMemoryPressure(MemoryPressureState aState);
+
+/**
+ * This function causes the main thread to fire a memory pressure event
+ * before processing the next event. We wake up the main thread by adding a
+ * dummy event to its event loop, so, unlike with
+ * NS_DispatchEventualMemoryPressure, this memory-pressure event is always
+ * fired relatively quickly, even if the event loop is otherwise empty.
+ *
+ * You may call this function from any thread.
+ */
+nsresult
+NS_DispatchMemoryPressure(MemoryPressureState aState);
+
+#endif // nsMemoryPressure_h__
diff --git a/xpcom/threads/nsProcess.h b/xpcom/threads/nsProcess.h
new file mode 100644
index 000000000..140944415
--- /dev/null
+++ b/xpcom/threads/nsProcess.h
@@ -0,0 +1,82 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef _nsPROCESSWIN_H_
+#define _nsPROCESSWIN_H_
+
+#if defined(XP_WIN)
+#define PROCESSMODEL_WINAPI
+#endif
+
+#include "mozilla/Attributes.h"
+#include "mozilla/Mutex.h"
+#include "nsIProcess.h"
+#include "nsIFile.h"
+#include "nsIThread.h"
+#include "nsIObserver.h"
+#include "nsIWeakReferenceUtils.h"
+#include "nsIObserver.h"
+#include "nsString.h"
+#ifndef XP_MACOSX
+#include "prproces.h"
+#endif
+#if defined(PROCESSMODEL_WINAPI)
+#include <windows.h>
+#include <shellapi.h>
+#endif
+
+#define NS_PROCESS_CID \
+{0x7b4eeb20, 0xd781, 0x11d4, \
+   {0x8A, 0x83, 0x00, 0x10, 0xa4, 0xe0, 0xc9, 0xca}}
+
+class nsProcess final
+  : public nsIProcess
+  , public nsIObserver
+{
+public:
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIPROCESS
+  NS_DECL_NSIOBSERVER
+
+  nsProcess();
+
+private:
+  ~nsProcess();
+  static void Monitor(void* aArg);
+  void ProcessComplete();
+  nsresult CopyArgsAndRunProcess(bool aBlocking, const char** aArgs,
+                                 uint32_t aCount, nsIObserver* aObserver,
+                                 bool aHoldWeak);
+  nsresult CopyArgsAndRunProcessw(bool aBlocking, const char16_t** aArgs,
+                                  uint32_t aCount, nsIObserver* aObserver,
+                                  bool aHoldWeak);
+  // The 'args' array is null-terminated.
+  nsresult RunProcess(bool aBlocking, char** aArgs, nsIObserver* aObserver,
+                      bool aHoldWeak, bool aArgsUTF8);
+
+  PRThread* mThread;
+  mozilla::Mutex mLock;
+  bool mShutdown;
+  bool mBlocking;
+
+  nsCOMPtr<nsIFile> mExecutable;
+  nsString mTargetPath;
+  int32_t mPid;
+  nsCOMPtr<nsIObserver> mObserver;
+  nsWeakPtr mWeakObserver;
+
+  // These members are modified by multiple threads, any accesses should be
+  // protected with mLock.
+  int32_t mExitValue;
+#if defined(PROCESSMODEL_WINAPI)
+  HANDLE mProcess;
+#elif !defined(XP_MACOSX)
+  PRProcess* mProcess;
+#endif
+};
+
+#endif
diff --git a/xpcom/threads/nsProcessCommon.cpp b/xpcom/threads/nsProcessCommon.cpp
new file mode 100644
index 000000000..709865a09
--- /dev/null
+++ b/xpcom/threads/nsProcessCommon.cpp
@@ -0,0 +1,663 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*****************************************************************************
+ *
+ * nsProcess is used to execute new processes and specify if you want to
+ * wait (blocking) or continue (non-blocking).
+ *
+ *****************************************************************************
+ */
+
+#include "mozilla/ArrayUtils.h"
+
+#include "nsCOMPtr.h"
+#include "nsAutoPtr.h"
+#include "nsMemory.h"
+#include "nsProcess.h"
+#include "prio.h"
+#include "prenv.h"
+#include "nsCRT.h"
+#include "nsThreadUtils.h"
+#include "nsIObserverService.h"
+#include "nsXULAppAPI.h"
+#include "mozilla/Services.h"
+
+#include <stdlib.h>
+
+#if defined(PROCESSMODEL_WINAPI)
+#include "prmem.h"
+#include "nsString.h"
+#include "nsLiteralString.h"
+#include "nsReadableUtils.h"
+#else
+#ifdef XP_MACOSX
+#include <crt_externs.h>
+#include <spawn.h>
+#include <sys/wait.h>
+#include <sys/errno.h>
+#endif
+#include <sys/types.h>
+#include <signal.h>
+#endif
+
+using namespace mozilla;
+
+#ifdef XP_MACOSX
+cpu_type_t pref_cpu_types[2] = {
+#if defined(__i386__)
+  CPU_TYPE_X86,
+#elif defined(__x86_64__)
+  CPU_TYPE_X86_64,
+#elif defined(__ppc__)
+  CPU_TYPE_POWERPC,
+#endif
+  CPU_TYPE_ANY
+};
+#endif
+
+//-------------------------------------------------------------------//
+// nsIProcess implementation
+//-------------------------------------------------------------------//
+NS_IMPL_ISUPPORTS(nsProcess, nsIProcess,
+                  nsIObserver)
+
+//Constructor
+nsProcess::nsProcess()
+  : mThread(nullptr)
+  , mLock("nsProcess.mLock")
+  , mShutdown(false)
+  , mBlocking(false)
+  , mPid(-1)
+  , mObserver(nullptr)
+  , mWeakObserver(nullptr)
+  , mExitValue(-1)
+#if !defined(XP_MACOSX)
+  , mProcess(nullptr)
+#endif
+{
+}
+
+//Destructor
+nsProcess::~nsProcess()
+{
+}
+
+NS_IMETHODIMP
+nsProcess::Init(nsIFile* aExecutable)
+{
+  if (mExecutable) {
+    return NS_ERROR_ALREADY_INITIALIZED;
+  }
+
+  if (NS_WARN_IF(!aExecutable)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  bool isFile;
+
+  //First make sure the file exists
+  nsresult rv = aExecutable->IsFile(&isFile);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (!isFile) {
+    return NS_ERROR_FAILURE;
+  }
+
+  //Store the nsIFile in mExecutable
+  mExecutable = aExecutable;
+  //Get the path because it is needed by the NSPR process creation
+#ifdef XP_WIN
+  rv = mExecutable->GetTarget(mTargetPath);
+  if (NS_FAILED(rv) || mTargetPath.IsEmpty())
+#endif
+    rv = mExecutable->GetPath(mTargetPath);
+
+  return rv;
+}
+
+
+#if defined(XP_WIN)
+// Out param `aWideCmdLine` must be PR_Freed by the caller.
+static int
+assembleCmdLine(char* const* aArgv, wchar_t** aWideCmdLine, UINT aCodePage)
+{
+  char* const* arg;
+  char* p;
+  char* q;
+  char* cmdLine;
+  int cmdLineSize;
+  int numBackslashes;
+  int i;
+  int argNeedQuotes;
+
+  /*
+   * Find out how large the command line buffer should be.
+   */
+  cmdLineSize = 0;
+  for (arg = aArgv; *arg; ++arg) {
+    /*
+     * \ and " need to be escaped by a \.  In the worst case,
+     * every character is a \ or ", so the string of length
+     * may double.  If we quote an argument, that needs two ".
+     * Finally, we need a space between arguments, and
+     * a null byte at the end of command line.
+     */
+    cmdLineSize += 2 * strlen(*arg)  /* \ and " need to be escaped */
+                   + 2               /* we quote every argument */
+                   + 1;              /* space in between, or final null */
+  }
+  p = cmdLine = (char*)PR_MALLOC(cmdLineSize * sizeof(char));
+  if (!p) {
+    return -1;
+  }
+
+  for (arg = aArgv; *arg; ++arg) {
+    /* Add a space to separates the arguments */
+    if (arg != aArgv) {
+      *p++ = ' ';
+    }
+    q = *arg;
+    numBackslashes = 0;
+    argNeedQuotes = 0;
+
+    /* If the argument contains white space, it needs to be quoted. */
+    if (strpbrk(*arg, " \f\n\r\t\v")) {
+      argNeedQuotes = 1;
+    }
+
+    if (argNeedQuotes) {
+      *p++ = '"';
+    }
+    while (*q) {
+      if (*q == '\\') {
+        numBackslashes++;
+        q++;
+      } else if (*q == '"') {
+        if (numBackslashes) {
+          /*
+           * Double the backslashes since they are followed
+           * by a quote
+           */
+          for (i = 0; i < 2 * numBackslashes; i++) {
+            *p++ = '\\';
+          }
+          numBackslashes = 0;
+        }
+        /* To escape the quote */
+        *p++ = '\\';
+        *p++ = *q++;
+      } else {
+        if (numBackslashes) {
+          /*
+           * Backslashes are not followed by a quote, so
+           * don't need to double the backslashes.
+           */
+          for (i = 0; i < numBackslashes; i++) {
+            *p++ = '\\';
+          }
+          numBackslashes = 0;
+        }
+        *p++ = *q++;
+      }
+    }
+
+    /* Now we are at the end of this argument */
+    if (numBackslashes) {
+      /*
+       * Double the backslashes if we have a quote string
+       * delimiter at the end.
+       */
+      if (argNeedQuotes) {
+        numBackslashes *= 2;
+      }
+      for (i = 0; i < numBackslashes; i++) {
+        *p++ = '\\';
+      }
+    }
+    if (argNeedQuotes) {
+      *p++ = '"';
+    }
+  }
+
+  *p = '\0';
+  int32_t numChars = MultiByteToWideChar(aCodePage, 0, cmdLine, -1, nullptr, 0);
+  *aWideCmdLine = (wchar_t*)PR_MALLOC(numChars * sizeof(wchar_t));
+  MultiByteToWideChar(aCodePage, 0, cmdLine, -1, *aWideCmdLine, numChars);
+  PR_Free(cmdLine);
+  return 0;
+}
+#endif
+
+void
+nsProcess::Monitor(void* aArg)
+{
+  RefPtr<nsProcess> process = dont_AddRef(static_cast<nsProcess*>(aArg));
+
+  if (!process->mBlocking) {
+    PR_SetCurrentThreadName("RunProcess");
+  }
+
+#if defined(PROCESSMODEL_WINAPI)
+  DWORD dwRetVal;
+  unsigned long exitCode = -1;
+
+  dwRetVal = WaitForSingleObject(process->mProcess, INFINITE);
+  if (dwRetVal != WAIT_FAILED) {
+    if (GetExitCodeProcess(process->mProcess, &exitCode) == FALSE) {
+      exitCode = -1;
+    }
+  }
+
+  // Lock in case Kill or GetExitCode are called during this
+  {
+    MutexAutoLock lock(process->mLock);
+    CloseHandle(process->mProcess);
+    process->mProcess = nullptr;
+    process->mExitValue = exitCode;
+    if (process->mShutdown) {
+      return;
+    }
+  }
+#else
+#ifdef XP_MACOSX
+  int exitCode = -1;
+  int status = 0;
+  pid_t result;
+  do {
+    result = waitpid(process->mPid, &status, 0);
+  } while (result == -1 && errno == EINTR);
+  if (result == process->mPid) {
+    if (WIFEXITED(status)) {
+      exitCode = WEXITSTATUS(status);
+    } else if (WIFSIGNALED(status)) {
+      exitCode = 256; // match NSPR's signal exit status
+    }
+  }
+#else
+  int32_t exitCode = -1;
+  if (PR_WaitProcess(process->mProcess, &exitCode) != PR_SUCCESS) {
+    exitCode = -1;
+  }
+#endif
+
+  // Lock in case Kill or GetExitCode are called during this
+  {
+    MutexAutoLock lock(process->mLock);
+#if !defined(XP_MACOSX)
+    process->mProcess = nullptr;
+#endif
+    process->mExitValue = exitCode;
+    if (process->mShutdown) {
+      return;
+    }
+  }
+#endif
+
+  // If we ran a background thread for the monitor then notify on the main
+  // thread
+  if (NS_IsMainThread()) {
+    process->ProcessComplete();
+  } else {
+    NS_DispatchToMainThread(NewRunnableMethod(process, &nsProcess::ProcessComplete));
+  }
+}
+
+void
+nsProcess::ProcessComplete()
+{
+  if (mThread) {
+    nsCOMPtr<nsIObserverService> os =
+      mozilla::services::GetObserverService();
+    if (os) {
+      os->RemoveObserver(this, "xpcom-shutdown");
+    }
+    PR_JoinThread(mThread);
+    mThread = nullptr;
+  }
+
+  const char* topic;
+  if (mExitValue < 0) {
+    topic = "process-failed";
+  } else {
+    topic = "process-finished";
+  }
+
+  mPid = -1;
+  nsCOMPtr<nsIObserver> observer;
+  if (mWeakObserver) {
+    observer = do_QueryReferent(mWeakObserver);
+  } else if (mObserver) {
+    observer = mObserver;
+  }
+  mObserver = nullptr;
+  mWeakObserver = nullptr;
+
+  if (observer) {
+    observer->Observe(NS_ISUPPORTS_CAST(nsIProcess*, this), topic, nullptr);
+  }
+}
+
+// XXXldb |aArgs| has the wrong const-ness
+NS_IMETHODIMP
+nsProcess::Run(bool aBlocking, const char** aArgs, uint32_t aCount)
+{
+  return CopyArgsAndRunProcess(aBlocking, aArgs, aCount, nullptr, false);
+}
+
+// XXXldb |aArgs| has the wrong const-ness
+NS_IMETHODIMP
+nsProcess::RunAsync(const char** aArgs, uint32_t aCount,
+                    nsIObserver* aObserver, bool aHoldWeak)
+{
+  return CopyArgsAndRunProcess(false, aArgs, aCount, aObserver, aHoldWeak);
+}
+
+nsresult
+nsProcess::CopyArgsAndRunProcess(bool aBlocking, const char** aArgs,
+                                 uint32_t aCount, nsIObserver* aObserver,
+                                 bool aHoldWeak)
+{
+  // Add one to the aCount for the program name and one for null termination.
+  char** my_argv = nullptr;
+  my_argv = (char**)moz_xmalloc(sizeof(char*) * (aCount + 2));
+  if (!my_argv) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  my_argv[0] = ToNewUTF8String(mTargetPath);
+
+  for (uint32_t i = 0; i < aCount; ++i) {
+    my_argv[i + 1] = const_cast<char*>(aArgs[i]);
+  }
+
+  my_argv[aCount + 1] = nullptr;
+
+  nsresult rv = RunProcess(aBlocking, my_argv, aObserver, aHoldWeak, false);
+
+  free(my_argv[0]);
+  free(my_argv);
+  return rv;
+}
+
+// XXXldb |aArgs| has the wrong const-ness
+NS_IMETHODIMP
+nsProcess::Runw(bool aBlocking, const char16_t** aArgs, uint32_t aCount)
+{
+  return CopyArgsAndRunProcessw(aBlocking, aArgs, aCount, nullptr, false);
+}
+
+// XXXldb |aArgs| has the wrong const-ness
+NS_IMETHODIMP
+nsProcess::RunwAsync(const char16_t** aArgs, uint32_t aCount,
+                     nsIObserver* aObserver, bool aHoldWeak)
+{
+  return CopyArgsAndRunProcessw(false, aArgs, aCount, aObserver, aHoldWeak);
+}
+
+nsresult
+nsProcess::CopyArgsAndRunProcessw(bool aBlocking, const char16_t** aArgs,
+                                  uint32_t aCount, nsIObserver* aObserver,
+                                  bool aHoldWeak)
+{
+  // Add one to the aCount for the program name and one for null termination.
+  char** my_argv = nullptr;
+  my_argv = (char**)moz_xmalloc(sizeof(char*) * (aCount + 2));
+  if (!my_argv) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  my_argv[0] = ToNewUTF8String(mTargetPath);
+
+  for (uint32_t i = 0; i < aCount; i++) {
+    my_argv[i + 1] = ToNewUTF8String(nsDependentString(aArgs[i]));
+  }
+
+  my_argv[aCount + 1] = nullptr;
+
+  nsresult rv = RunProcess(aBlocking, my_argv, aObserver, aHoldWeak, true);
+
+  for (uint32_t i = 0; i <= aCount; ++i) {
+    free(my_argv[i]);
+  }
+  free(my_argv);
+  return rv;
+}
+
+nsresult
+nsProcess::RunProcess(bool aBlocking, char** aMyArgv, nsIObserver* aObserver,
+                      bool aHoldWeak, bool aArgsUTF8)
+{
+  NS_WARNING_ASSERTION(!XRE_IsContentProcess(),
+                       "No launching of new processes in the content process");
+
+  if (NS_WARN_IF(!mExecutable)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  if (NS_WARN_IF(mThread)) {
+    return NS_ERROR_ALREADY_INITIALIZED;
+  }
+
+  if (aObserver) {
+    if (aHoldWeak) {
+      mWeakObserver = do_GetWeakReference(aObserver);
+      if (!mWeakObserver) {
+        return NS_NOINTERFACE;
+      }
+    } else {
+      mObserver = aObserver;
+    }
+  }
+
+  mExitValue = -1;
+  mPid = -1;
+
+#if defined(PROCESSMODEL_WINAPI)
+  BOOL retVal;
+  wchar_t* cmdLine = nullptr;
+
+  // |aMyArgv| is null-terminated and always starts with the program path. If
+  // the second slot is non-null then arguments are being passed.
+  if (aMyArgv[1] && assembleCmdLine(aMyArgv + 1, &cmdLine,
+                                    aArgsUTF8 ? CP_UTF8 : CP_ACP) == -1) {
+    return NS_ERROR_FILE_EXECUTION_FAILED;
+  }
+
+  /* The SEE_MASK_NO_CONSOLE flag is important to prevent console windows
+   * from appearing. This makes behavior the same on all platforms. The flag
+   * will not have any effect on non-console applications.
+   */
+
+  // The program name in aMyArgv[0] is always UTF-8
+  NS_ConvertUTF8toUTF16 wideFile(aMyArgv[0]);
+
+  SHELLEXECUTEINFOW sinfo;
+  memset(&sinfo, 0, sizeof(SHELLEXECUTEINFOW));
+  sinfo.cbSize = sizeof(SHELLEXECUTEINFOW);
+  sinfo.hwnd   = nullptr;
+  sinfo.lpFile = wideFile.get();
+  sinfo.nShow  = SW_SHOWNORMAL;
+  sinfo.fMask  = SEE_MASK_FLAG_DDEWAIT |
+                 SEE_MASK_NO_CONSOLE |
+                 SEE_MASK_NOCLOSEPROCESS;
+
+  if (cmdLine) {
+    sinfo.lpParameters = cmdLine;
+  }
+
+  retVal = ShellExecuteExW(&sinfo);
+  if (!retVal) {
+    return NS_ERROR_FILE_EXECUTION_FAILED;
+  }
+
+  mProcess = sinfo.hProcess;
+
+  if (cmdLine) {
+    PR_Free(cmdLine);
+  }
+
+  mPid = GetProcessId(mProcess);
+#elif defined(XP_MACOSX)
+  // Initialize spawn attributes.
+  posix_spawnattr_t spawnattr;
+  if (posix_spawnattr_init(&spawnattr) != 0) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Set spawn attributes.
+  size_t attr_count = ArrayLength(pref_cpu_types);
+  size_t attr_ocount = 0;
+  if (posix_spawnattr_setbinpref_np(&spawnattr, attr_count, pref_cpu_types,
+                                    &attr_ocount) != 0 ||
+      attr_ocount != attr_count) {
+    posix_spawnattr_destroy(&spawnattr);
+    return NS_ERROR_FAILURE;
+  }
+
+  // Note: |aMyArgv| is already null-terminated as required by posix_spawnp.
+  pid_t newPid = 0;
+  int result = posix_spawnp(&newPid, aMyArgv[0], nullptr, &spawnattr, aMyArgv,
+                            *_NSGetEnviron());
+  mPid = static_cast<int32_t>(newPid);
+
+  posix_spawnattr_destroy(&spawnattr);
+
+  if (result != 0) {
+    return NS_ERROR_FAILURE;
+  }
+#else
+  mProcess = PR_CreateProcess(aMyArgv[0], aMyArgv, nullptr, nullptr);
+  if (!mProcess) {
+    return NS_ERROR_FAILURE;
+  }
+  struct MYProcess
+  {
+    uint32_t pid;
+  };
+  MYProcess* ptrProc = (MYProcess*)mProcess;
+  mPid = ptrProc->pid;
+#endif
+
+  NS_ADDREF_THIS();
+  mBlocking = aBlocking;
+  if (aBlocking) {
+    Monitor(this);
+    if (mExitValue < 0) {
+      return NS_ERROR_FILE_EXECUTION_FAILED;
+    }
+  } else {
+    mThread = PR_CreateThread(PR_SYSTEM_THREAD, Monitor, this,
+                              PR_PRIORITY_NORMAL, PR_GLOBAL_THREAD,
+                              PR_JOINABLE_THREAD, 0);
+    if (!mThread) {
+      NS_RELEASE_THIS();
+      return NS_ERROR_FAILURE;
+    }
+
+    // It isn't a failure if we just can't watch for shutdown
+    nsCOMPtr<nsIObserverService> os =
+      mozilla::services::GetObserverService();
+    if (os) {
+      os->AddObserver(this, "xpcom-shutdown", false);
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProcess::GetIsRunning(bool* aIsRunning)
+{
+  if (mThread) {
+    *aIsRunning = true;
+  } else {
+    *aIsRunning = false;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProcess::GetPid(uint32_t* aPid)
+{
+  if (!mThread) {
+    return NS_ERROR_FAILURE;
+  }
+  if (mPid < 0) {
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+  *aPid = mPid;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProcess::Kill()
+{
+  if (!mThread) {
+    return NS_ERROR_FAILURE;
+  }
+
+  {
+    MutexAutoLock lock(mLock);
+#if defined(PROCESSMODEL_WINAPI)
+    if (TerminateProcess(mProcess, 0) == 0) {
+      return NS_ERROR_FAILURE;
+    }
+#elif defined(XP_MACOSX)
+    if (kill(mPid, SIGKILL) != 0) {
+      return NS_ERROR_FAILURE;
+    }
+#else
+    if (!mProcess || (PR_KillProcess(mProcess) != PR_SUCCESS)) {
+      return NS_ERROR_FAILURE;
+    }
+#endif
+  }
+
+  // We must null out mThread if we want IsRunning to return false immediately
+  // after this call.
+  nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
+  if (os) {
+    os->RemoveObserver(this, "xpcom-shutdown");
+  }
+  PR_JoinThread(mThread);
+  mThread = nullptr;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProcess::GetExitValue(int32_t* aExitValue)
+{
+  MutexAutoLock lock(mLock);
+
+  *aExitValue = mExitValue;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProcess::Observe(nsISupports* aSubject, const char* aTopic,
+                   const char16_t* aData)
+{
+  // Shutting down, drop all references
+  if (mThread) {
+    nsCOMPtr<nsIObserverService> os =
+      mozilla::services::GetObserverService();
+    if (os) {
+      os->RemoveObserver(this, "xpcom-shutdown");
+    }
+    mThread = nullptr;
+  }
+
+  mObserver = nullptr;
+  mWeakObserver = nullptr;
+
+  MutexAutoLock lock(mLock);
+  mShutdown = true;
+
+  return NS_OK;
+}
diff --git a/xpcom/threads/nsThread.cpp b/xpcom/threads/nsThread.cpp
new file mode 100644
index 000000000..63bd28ca3
--- /dev/null
+++ b/xpcom/threads/nsThread.cpp
@@ -0,0 +1,1500 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsThread.h"
+
+#include "base/message_loop.h"
+
+// Chromium's logging can sometimes leak through...
+#ifdef LOG
+#undef LOG
+#endif
+
+#include "mozilla/ReentrantMonitor.h"
+#include "nsMemoryPressure.h"
+#include "nsThreadManager.h"
+#include "nsIClassInfoImpl.h"
+#include "nsAutoPtr.h"
+#include "nsCOMPtr.h"
+#include "nsQueryObject.h"
+#include "pratom.h"
+#include "mozilla/CycleCollectedJSContext.h"
+#include "mozilla/Logging.h"
+#include "nsIObserverService.h"
+#include "mozilla/HangMonitor.h"
+#include "mozilla/IOInterposer.h"
+#include "mozilla/ipc/MessageChannel.h"
+#include "mozilla/ipc/BackgroundChild.h"
+#include "mozilla/Services.h"
+#include "nsXPCOMPrivate.h"
+#include "mozilla/ChaosMode.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/Unused.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "nsIIdlePeriod.h"
+#include "nsIIncrementalRunnable.h"
+#include "nsThreadSyncDispatch.h"
+#include "LeakRefPtr.h"
+
+#ifdef MOZ_CRASHREPORTER
+#include "nsServiceManagerUtils.h"
+#include "nsICrashReporter.h"
+#include "mozilla/dom/ContentChild.h"
+#endif
+
+#ifdef XP_LINUX
+#include <sys/time.h>
+#include <sys/resource.h>
+#include <sched.h>
+#endif
+
+#define HAVE_UALARM _BSD_SOURCE || (_XOPEN_SOURCE >= 500 ||                 \
+                      _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) &&           \
+                      !(_POSIX_C_SOURCE >= 200809L || _XOPEN_SOURCE >= 700)
+
+#if defined(XP_LINUX) && !defined(ANDROID) && defined(_GNU_SOURCE)
+#define HAVE_SCHED_SETAFFINITY
+#endif
+
+#ifdef XP_MACOSX
+#include <mach/mach.h>
+#include <mach/thread_policy.h>
+#endif
+
+#ifdef MOZ_CANARY
+# include <unistd.h>
+# include <execinfo.h>
+# include <signal.h>
+# include <fcntl.h>
+# include "nsXULAppAPI.h"
+#endif
+
+#if defined(NS_FUNCTION_TIMER) && defined(_MSC_VER)
+#include "nsTimerImpl.h"
+#include "mozilla/StackWalk.h"
+#endif
+#ifdef NS_FUNCTION_TIMER
+#include "nsCRT.h"
+#endif
+
+#ifdef MOZ_TASK_TRACER
+#include "GeckoTaskTracer.h"
+#include "TracedTaskCommon.h"
+using namespace mozilla::tasktracer;
+#endif
+
+using namespace mozilla;
+
+static LazyLogModule sThreadLog("nsThread");
+#ifdef LOG
+#undef LOG
+#endif
+#define LOG(args) MOZ_LOG(sThreadLog, mozilla::LogLevel::Debug, args)
+
+NS_DECL_CI_INTERFACE_GETTER(nsThread)
+
+//-----------------------------------------------------------------------------
+// Because we do not have our own nsIFactory, we have to implement nsIClassInfo
+// somewhat manually.
+
+class nsThreadClassInfo : public nsIClassInfo
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED  // no mRefCnt
+  NS_DECL_NSICLASSINFO
+
+  nsThreadClassInfo()
+  {
+  }
+};
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsThreadClassInfo::AddRef()
+{
+  return 2;
+}
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsThreadClassInfo::Release()
+{
+  return 1;
+}
+NS_IMPL_QUERY_INTERFACE(nsThreadClassInfo, nsIClassInfo)
+
+NS_IMETHODIMP
+nsThreadClassInfo::GetInterfaces(uint32_t* aCount, nsIID*** aArray)
+{
+  return NS_CI_INTERFACE_GETTER_NAME(nsThread)(aCount, aArray);
+}
+
+NS_IMETHODIMP
+nsThreadClassInfo::GetScriptableHelper(nsIXPCScriptable** aResult)
+{
+  *aResult = nullptr;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadClassInfo::GetContractID(char** aResult)
+{
+  *aResult = nullptr;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadClassInfo::GetClassDescription(char** aResult)
+{
+  *aResult = nullptr;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadClassInfo::GetClassID(nsCID** aResult)
+{
+  *aResult = nullptr;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadClassInfo::GetFlags(uint32_t* aResult)
+{
+  *aResult = THREADSAFE;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadClassInfo::GetClassIDNoAlloc(nsCID* aResult)
+{
+  return NS_ERROR_NOT_AVAILABLE;
+}
+
+//-----------------------------------------------------------------------------
+
+NS_IMPL_ADDREF(nsThread)
+NS_IMPL_RELEASE(nsThread)
+NS_INTERFACE_MAP_BEGIN(nsThread)
+  NS_INTERFACE_MAP_ENTRY(nsIThread)
+  NS_INTERFACE_MAP_ENTRY(nsIThreadInternal)
+  NS_INTERFACE_MAP_ENTRY(nsIEventTarget)
+  NS_INTERFACE_MAP_ENTRY(nsISupportsPriority)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIThread)
+  if (aIID.Equals(NS_GET_IID(nsIClassInfo))) {
+    static nsThreadClassInfo sThreadClassInfo;
+    foundInterface = static_cast<nsIClassInfo*>(&sThreadClassInfo);
+  } else
+NS_INTERFACE_MAP_END
+NS_IMPL_CI_INTERFACE_GETTER(nsThread, nsIThread, nsIThreadInternal,
+                            nsIEventTarget, nsISupportsPriority)
+
+//-----------------------------------------------------------------------------
+
+class nsThreadStartupEvent : public Runnable
+{
+public:
+  nsThreadStartupEvent()
+    : mMon("nsThreadStartupEvent.mMon")
+    , mInitialized(false)
+  {
+  }
+
+  // This method does not return until the thread startup object is in the
+  // completion state.
+  void Wait()
+  {
+    ReentrantMonitorAutoEnter mon(mMon);
+    while (!mInitialized) {
+      mon.Wait();
+    }
+  }
+
+  // This method needs to be public to support older compilers (xlC_r on AIX).
+  // It should be called directly as this class type is reference counted.
+  virtual ~nsThreadStartupEvent() {}
+
+private:
+  NS_IMETHOD Run() override
+  {
+    ReentrantMonitorAutoEnter mon(mMon);
+    mInitialized = true;
+    mon.Notify();
+    return NS_OK;
+  }
+
+  ReentrantMonitor mMon;
+  bool mInitialized;
+};
+//-----------------------------------------------------------------------------
+
+namespace {
+class DelayedRunnable : public Runnable,
+                        public nsITimerCallback
+{
+public:
+  DelayedRunnable(already_AddRefed<nsIThread> aTargetThread,
+                  already_AddRefed<nsIRunnable> aRunnable,
+                  uint32_t aDelay)
+    : mTargetThread(aTargetThread),
+      mWrappedRunnable(aRunnable),
+      mDelayedFrom(TimeStamp::NowLoRes()),
+      mDelay(aDelay)
+  { }
+
+  NS_DECL_ISUPPORTS_INHERITED
+
+  nsresult Init()
+  {
+    nsresult rv;
+    mTimer = do_CreateInstance(NS_TIMER_CONTRACTID, &rv);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    MOZ_ASSERT(mTimer);
+    rv = mTimer->SetTarget(mTargetThread);
+
+    NS_ENSURE_SUCCESS(rv, rv);
+    return mTimer->InitWithCallback(this, mDelay, nsITimer::TYPE_ONE_SHOT);
+  }
+
+  nsresult DoRun()
+  {
+    nsCOMPtr<nsIRunnable> r = mWrappedRunnable.forget();
+    return r->Run();
+  }
+
+  NS_IMETHOD Run() override
+  {
+    // Already ran?
+    if (!mWrappedRunnable) {
+      return NS_OK;
+    }
+
+    // Are we too early?
+    if ((TimeStamp::NowLoRes() - mDelayedFrom).ToMilliseconds() < mDelay) {
+      return NS_OK; // Let the nsITimer run us.
+    }
+
+    mTimer->Cancel();
+    return DoRun();
+  }
+
+  NS_IMETHOD Notify(nsITimer* aTimer) override
+  {
+    // If we already ran, the timer should have been canceled.
+    MOZ_ASSERT(mWrappedRunnable);
+    MOZ_ASSERT(aTimer == mTimer);
+
+    return DoRun();
+  }
+
+private:
+  ~DelayedRunnable() {}
+
+  nsCOMPtr<nsIThread> mTargetThread;
+  nsCOMPtr<nsIRunnable> mWrappedRunnable;
+  nsCOMPtr<nsITimer> mTimer;
+  TimeStamp mDelayedFrom;
+  uint32_t mDelay;
+};
+
+NS_IMPL_ISUPPORTS_INHERITED(DelayedRunnable, Runnable, nsITimerCallback)
+
+} // anonymous namespace
+
+//-----------------------------------------------------------------------------
+
+struct nsThreadShutdownContext
+{
+  nsThreadShutdownContext(NotNull<nsThread*> aTerminatingThread,
+                          NotNull<nsThread*> aJoiningThread,
+                          bool      aAwaitingShutdownAck)
+    : mTerminatingThread(aTerminatingThread)
+    , mJoiningThread(aJoiningThread)
+    , mAwaitingShutdownAck(aAwaitingShutdownAck)
+  {
+    MOZ_COUNT_CTOR(nsThreadShutdownContext);
+  }
+  ~nsThreadShutdownContext()
+  {
+    MOZ_COUNT_DTOR(nsThreadShutdownContext);
+  }
+
+  // NB: This will be the last reference.
+  NotNull<RefPtr<nsThread>> mTerminatingThread;
+  NotNull<nsThread*> mJoiningThread;
+  bool mAwaitingShutdownAck;
+};
+
+// This event is responsible for notifying nsThread::Shutdown that it is time
+// to call PR_JoinThread. It implements nsICancelableRunnable so that it can
+// run on a DOM Worker thread (where all events must implement
+// nsICancelableRunnable.)
+class nsThreadShutdownAckEvent : public CancelableRunnable
+{
+public:
+  explicit nsThreadShutdownAckEvent(NotNull<nsThreadShutdownContext*> aCtx)
+    : mShutdownContext(aCtx)
+  {
+  }
+  NS_IMETHOD Run() override
+  {
+    mShutdownContext->mTerminatingThread->ShutdownComplete(mShutdownContext);
+    return NS_OK;
+  }
+  nsresult Cancel() override
+  {
+    return Run();
+  }
+private:
+  virtual ~nsThreadShutdownAckEvent() { }
+
+  NotNull<nsThreadShutdownContext*> mShutdownContext;
+};
+
+// This event is responsible for setting mShutdownContext
+class nsThreadShutdownEvent : public Runnable
+{
+public:
+  nsThreadShutdownEvent(NotNull<nsThread*> aThr,
+                        NotNull<nsThreadShutdownContext*> aCtx)
+    : mThread(aThr)
+    , mShutdownContext(aCtx)
+  {
+  }
+  NS_IMETHOD Run() override
+  {
+    mThread->mShutdownContext = mShutdownContext;
+    MessageLoop::current()->Quit();
+    return NS_OK;
+  }
+private:
+  NotNull<RefPtr<nsThread>> mThread;
+  NotNull<nsThreadShutdownContext*> mShutdownContext;
+};
+
+//-----------------------------------------------------------------------------
+
+static void
+SetThreadAffinity(unsigned int cpu)
+{
+#ifdef HAVE_SCHED_SETAFFINITY
+  cpu_set_t cpus;
+  CPU_ZERO(&cpus);
+  CPU_SET(cpu, &cpus);
+  sched_setaffinity(0, sizeof(cpus), &cpus);
+  // Don't assert sched_setaffinity's return value because it intermittently (?)
+  // fails with EINVAL on Linux x64 try runs.
+#elif defined(XP_MACOSX)
+  // OS X does not provide APIs to pin threads to specific processors, but you
+  // can tag threads as belonging to the same "affinity set" and the OS will try
+  // to run them on the same processor. To run threads on different processors,
+  // tag them as belonging to different affinity sets. Tag 0, the default, means
+  // "no affinity" so let's pretend each CPU has its own tag `cpu+1`.
+  thread_affinity_policy_data_t policy;
+  policy.affinity_tag = cpu + 1;
+  MOZ_ALWAYS_TRUE(thread_policy_set(mach_thread_self(), THREAD_AFFINITY_POLICY,
+                                    &policy.affinity_tag, 1) == KERN_SUCCESS);
+#elif defined(XP_WIN)
+  MOZ_ALWAYS_TRUE(SetThreadIdealProcessor(GetCurrentThread(), cpu) != -1);
+#endif
+}
+
+static void
+SetupCurrentThreadForChaosMode()
+{
+  if (!ChaosMode::isActive(ChaosFeature::ThreadScheduling)) {
+    return;
+  }
+
+#ifdef XP_LINUX
+  // PR_SetThreadPriority doesn't really work since priorities >
+  // PR_PRIORITY_NORMAL can't be set by non-root users. Instead we'll just use
+  // setpriority(2) to set random 'nice values'. In regular Linux this is only
+  // a dynamic adjustment so it still doesn't really do what we want, but tools
+  // like 'rr' can be more aggressive about honoring these values.
+  // Some of these calls may fail due to trying to lower the priority
+  // (e.g. something may have already called setpriority() for this thread).
+  // This makes it hard to have non-main threads with higher priority than the
+  // main thread, but that's hard to fix. Tools like rr can choose to honor the
+  // requested values anyway.
+  // Use just 4 priorities so there's a reasonable chance of any two threads
+  // having equal priority.
+  setpriority(PRIO_PROCESS, 0, ChaosMode::randomUint32LessThan(4));
+#else
+  // We should set the affinity here but NSPR doesn't provide a way to expose it.
+  uint32_t priority = ChaosMode::randomUint32LessThan(PR_PRIORITY_LAST + 1);
+  PR_SetThreadPriority(PR_GetCurrentThread(), PRThreadPriority(priority));
+#endif
+
+  // Force half the threads to CPU 0 so they compete for CPU
+  if (ChaosMode::randomUint32LessThan(2)) {
+    SetThreadAffinity(0);
+  }
+}
+
+/*static*/ void
+nsThread::ThreadFunc(void* aArg)
+{
+  using mozilla::ipc::BackgroundChild;
+
+  nsThread* self = static_cast<nsThread*>(aArg);  // strong reference
+  self->mThread = PR_GetCurrentThread();
+  SetupCurrentThreadForChaosMode();
+
+  // Inform the ThreadManager
+  nsThreadManager::get().RegisterCurrentThread(*self);
+
+  mozilla::IOInterposer::RegisterCurrentThread();
+
+  // Wait for and process startup event
+  nsCOMPtr<nsIRunnable> event;
+  {
+    MutexAutoLock lock(self->mLock);
+    if (!self->mEvents->GetEvent(true, getter_AddRefs(event), lock)) {
+      NS_WARNING("failed waiting for thread startup event");
+      return;
+    }
+  }
+  event->Run();  // unblocks nsThread::Init
+  event = nullptr;
+
+  {
+    // Scope for MessageLoop.
+    nsAutoPtr<MessageLoop> loop(
+      new MessageLoop(MessageLoop::TYPE_MOZILLA_NONMAINTHREAD, self));
+
+    // Now, process incoming events...
+    loop->Run();
+
+    BackgroundChild::CloseForCurrentThread();
+
+    // NB: The main thread does not shut down here!  It shuts down via
+    // nsThreadManager::Shutdown.
+
+    // Do NS_ProcessPendingEvents but with special handling to set
+    // mEventsAreDoomed atomically with the removal of the last event. The key
+    // invariant here is that we will never permit PutEvent to succeed if the
+    // event would be left in the queue after our final call to
+    // NS_ProcessPendingEvents. We also have to keep processing events as long
+    // as we have outstanding mRequestedShutdownContexts.
+    while (true) {
+      // Check and see if we're waiting on any threads.
+      self->WaitForAllAsynchronousShutdowns();
+
+      {
+        MutexAutoLock lock(self->mLock);
+        if (!self->mEvents->HasPendingEvent(lock)) {
+          // No events in the queue, so we will stop now. Don't let any more
+          // events be added, since they won't be processed. It is critical
+          // that no PutEvent can occur between testing that the event queue is
+          // empty and setting mEventsAreDoomed!
+          self->mEventsAreDoomed = true;
+          break;
+        }
+      }
+      NS_ProcessPendingEvents(self);
+    }
+  }
+
+  mozilla::IOInterposer::UnregisterCurrentThread();
+
+  // Inform the threadmanager that this thread is going away
+  nsThreadManager::get().UnregisterCurrentThread(*self);
+
+  // Dispatch shutdown ACK
+  NotNull<nsThreadShutdownContext*> context =
+    WrapNotNull(self->mShutdownContext);
+  MOZ_ASSERT(context->mTerminatingThread == self);
+  event = do_QueryObject(new nsThreadShutdownAckEvent(context));
+  context->mJoiningThread->Dispatch(event, NS_DISPATCH_NORMAL);
+
+  // Release any observer of the thread here.
+  self->SetObserver(nullptr);
+
+#ifdef MOZ_TASK_TRACER
+  FreeTraceInfo();
+#endif
+
+  NS_RELEASE(self);
+}
+
+//-----------------------------------------------------------------------------
+
+#ifdef MOZ_CRASHREPORTER
+// Tell the crash reporter to save a memory report if our heuristics determine
+// that an OOM failure is likely to occur soon.
+// Memory usage will not be checked more than every 30 seconds or saved more
+// than every 3 minutes
+// If |aShouldSave == kForceReport|, a report will be saved regardless of
+// whether the process is low on memory or not. However, it will still not be
+// saved if a report was saved less than 3 minutes ago.
+bool
+nsThread::SaveMemoryReportNearOOM(ShouldSaveMemoryReport aShouldSave)
+{
+  // Keep an eye on memory usage (cheap, ~7ms) somewhat frequently,
+  // but save memory reports (expensive, ~75ms) less frequently.
+  const size_t kLowMemoryCheckSeconds = 30;
+  const size_t kLowMemorySaveSeconds = 3 * 60;
+
+  static TimeStamp nextCheck = TimeStamp::NowLoRes()
+    + TimeDuration::FromSeconds(kLowMemoryCheckSeconds);
+  static bool recentlySavedReport = false; // Keeps track of whether a report
+                                           // was saved last time we checked
+
+  // Are we checking again too soon?
+  TimeStamp now = TimeStamp::NowLoRes();
+  if ((aShouldSave == ShouldSaveMemoryReport::kMaybeReport ||
+      recentlySavedReport) && now < nextCheck) {
+    return false;
+  }
+
+  bool needMemoryReport = (aShouldSave == ShouldSaveMemoryReport::kForceReport);
+#ifdef XP_WIN // XXX implement on other platforms as needed
+  // If the report is forced there is no need to check whether it is necessary
+  if (aShouldSave != ShouldSaveMemoryReport::kForceReport) {
+    const size_t LOWMEM_THRESHOLD_VIRTUAL = 200 * 1024 * 1024;
+    MEMORYSTATUSEX statex;
+    statex.dwLength = sizeof(statex);
+    if (GlobalMemoryStatusEx(&statex)) {
+      if (statex.ullAvailVirtual < LOWMEM_THRESHOLD_VIRTUAL) {
+        needMemoryReport = true;
+      }
+    }
+  }
+#endif
+
+  if (needMemoryReport) {
+    if (XRE_IsContentProcess()) {
+      dom::ContentChild* cc = dom::ContentChild::GetSingleton();
+      if (cc) {
+        cc->SendNotifyLowMemory();
+      }
+    } else {
+      nsCOMPtr<nsICrashReporter> cr =
+        do_GetService("@mozilla.org/toolkit/crash-reporter;1");
+      if (cr) {
+        cr->SaveMemoryReport();
+      }
+    }
+    recentlySavedReport = true;
+    nextCheck = now + TimeDuration::FromSeconds(kLowMemorySaveSeconds);
+  } else {
+    recentlySavedReport = false;
+    nextCheck = now + TimeDuration::FromSeconds(kLowMemoryCheckSeconds);
+  }
+
+  return recentlySavedReport;
+}
+#endif
+
+#ifdef MOZ_CANARY
+int sCanaryOutputFD = -1;
+#endif
+
+nsThread::nsThread(MainThreadFlag aMainThread, uint32_t aStackSize)
+  : mLock("nsThread.mLock")
+  , mScriptObserver(nullptr)
+  , mEvents(WrapNotNull(&mEventsRoot))
+  , mEventsRoot(mLock)
+  , mIdleEventsAvailable(mLock, "[nsThread.mEventsAvailable]")
+  , mIdleEvents(mIdleEventsAvailable, nsEventQueue::eNormalQueue)
+  , mPriority(PRIORITY_NORMAL)
+  , mThread(nullptr)
+  , mNestedEventLoopDepth(0)
+  , mStackSize(aStackSize)
+  , mShutdownContext(nullptr)
+  , mShutdownRequired(false)
+  , mEventsAreDoomed(false)
+  , mIsMainThread(aMainThread)
+  , mCanInvokeJS(false)
+{
+}
+
+nsThread::~nsThread()
+{
+  NS_ASSERTION(mRequestedShutdownContexts.IsEmpty(),
+               "shouldn't be waiting on other threads to shutdown");
+#ifdef DEBUG
+  // We deliberately leak these so they can be tracked by the leak checker.
+  // If you're having nsThreadShutdownContext leaks, you can set:
+  //   XPCOM_MEM_LOG_CLASSES=nsThreadShutdownContext
+  // during a test run and that will at least tell you what thread is
+  // requesting shutdown on another, which can be helpful for diagnosing
+  // the leak.
+  for (size_t i = 0; i < mRequestedShutdownContexts.Length(); ++i) {
+    Unused << mRequestedShutdownContexts[i].forget();
+  }
+#endif
+}
+
+nsresult
+nsThread::Init()
+{
+  // spawn thread and wait until it is fully setup
+  RefPtr<nsThreadStartupEvent> startup = new nsThreadStartupEvent();
+
+  NS_ADDREF_THIS();
+
+  mIdlePeriod = new IdlePeriod();
+
+  mShutdownRequired = true;
+
+  // ThreadFunc is responsible for setting mThread
+  if (!PR_CreateThread(PR_USER_THREAD, ThreadFunc, this,
+                       PR_PRIORITY_NORMAL, PR_GLOBAL_THREAD,
+                       PR_JOINABLE_THREAD, mStackSize)) {
+    NS_RELEASE_THIS();
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  // ThreadFunc will wait for this event to be run before it tries to access
+  // mThread.  By delaying insertion of this event into the queue, we ensure
+  // that mThread is set properly.
+  {
+    MutexAutoLock lock(mLock);
+    mEventsRoot.PutEvent(startup, lock); // retain a reference
+  }
+
+  // Wait for thread to call ThreadManager::SetupCurrentThread, which completes
+  // initialization of ThreadFunc.
+  startup->Wait();
+  return NS_OK;
+}
+
+nsresult
+nsThread::InitCurrentThread()
+{
+  mThread = PR_GetCurrentThread();
+  SetupCurrentThreadForChaosMode();
+
+  mIdlePeriod = new IdlePeriod();
+
+  nsThreadManager::get().RegisterCurrentThread(*this);
+  return NS_OK;
+}
+
+nsresult
+nsThread::PutEvent(nsIRunnable* aEvent, nsNestedEventTarget* aTarget)
+{
+  nsCOMPtr<nsIRunnable> event(aEvent);
+  return PutEvent(event.forget(), aTarget);
+}
+
+nsresult
+nsThread::PutEvent(already_AddRefed<nsIRunnable> aEvent, nsNestedEventTarget* aTarget)
+{
+  // We want to leak the reference when we fail to dispatch it, so that
+  // we won't release the event in a wrong thread.
+  LeakRefPtr<nsIRunnable> event(Move(aEvent));
+  nsCOMPtr<nsIThreadObserver> obs;
+
+  {
+    MutexAutoLock lock(mLock);
+    nsChainedEventQueue* queue = aTarget ? aTarget->mQueue : &mEventsRoot;
+    if (!queue || (queue == &mEventsRoot && mEventsAreDoomed)) {
+      NS_WARNING("An event was posted to a thread that will never run it (rejected)");
+      return NS_ERROR_UNEXPECTED;
+    }
+    queue->PutEvent(event.take(), lock);
+
+    // Make sure to grab the observer before dropping the lock, otherwise the
+    // event that we just placed into the queue could run and eventually delete
+    // this nsThread before the calling thread is scheduled again. We would then
+    // crash while trying to access a dead nsThread.
+    obs = mObserver;
+  }
+
+  if (obs) {
+    obs->OnDispatchedEvent(this);
+  }
+
+  return NS_OK;
+}
+
+nsresult
+nsThread::DispatchInternal(already_AddRefed<nsIRunnable> aEvent, uint32_t aFlags,
+                           nsNestedEventTarget* aTarget)
+{
+  // We want to leak the reference when we fail to dispatch it, so that
+  // we won't release the event in a wrong thread.
+  LeakRefPtr<nsIRunnable> event(Move(aEvent));
+  if (NS_WARN_IF(!event)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  if (gXPCOMThreadsShutDown && MAIN_THREAD != mIsMainThread && !aTarget) {
+    NS_ASSERTION(false, "Failed Dispatch after xpcom-shutdown-threads");
+    return NS_ERROR_ILLEGAL_DURING_SHUTDOWN;
+  }
+
+#ifdef MOZ_TASK_TRACER
+  nsCOMPtr<nsIRunnable> tracedRunnable = CreateTracedRunnable(event.take());
+  (static_cast<TracedRunnable*>(tracedRunnable.get()))->DispatchTask();
+  // XXX tracedRunnable will always leaked when we fail to disptch.
+  event = tracedRunnable.forget();
+#endif
+
+  if (aFlags & DISPATCH_SYNC) {
+    nsThread* thread = nsThreadManager::get().GetCurrentThread();
+    if (NS_WARN_IF(!thread)) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+
+    // XXX we should be able to do something better here... we should
+    //     be able to monitor the slot occupied by this event and use
+    //     that to tell us when the event has been processed.
+
+    RefPtr<nsThreadSyncDispatch> wrapper =
+      new nsThreadSyncDispatch(thread, event.take());
+    nsresult rv = PutEvent(wrapper, aTarget); // hold a ref
+    // Don't wait for the event to finish if we didn't dispatch it...
+    if (NS_FAILED(rv)) {
+      // PutEvent leaked the wrapper runnable object on failure, so we
+      // explicitly release this object once for that. Note that this
+      // object will be released again soon because it exits the scope.
+      wrapper.get()->Release();
+      return rv;
+    }
+
+    // Allows waiting; ensure no locks are held that would deadlock us!
+    while (wrapper->IsPending()) {
+      NS_ProcessNextEvent(thread, true);
+    }
+    return NS_OK;
+  }
+
+  NS_ASSERTION(aFlags == NS_DISPATCH_NORMAL ||
+               aFlags == NS_DISPATCH_AT_END, "unexpected dispatch flags");
+  return PutEvent(event.take(), aTarget);
+}
+
+bool
+nsThread::nsChainedEventQueue::GetEvent(bool aMayWait, nsIRunnable** aEvent,
+                                        mozilla::MutexAutoLock& aProofOfLock)
+{
+  bool retVal = false;
+  do {
+    if (mProcessSecondaryQueueRunnable) {
+      MOZ_ASSERT(mSecondaryQueue->HasPendingEvent(aProofOfLock));
+      retVal = mSecondaryQueue->GetEvent(aMayWait, aEvent, aProofOfLock);
+      MOZ_ASSERT(*aEvent);
+      mProcessSecondaryQueueRunnable = false;
+      return retVal;
+    }
+
+    // We don't want to wait if mSecondaryQueue has some events.
+    bool reallyMayWait =
+      aMayWait && !mSecondaryQueue->HasPendingEvent(aProofOfLock);
+    retVal =
+      mNormalQueue->GetEvent(reallyMayWait, aEvent, aProofOfLock);
+
+    // Let's see if we should next time process an event from the secondary
+    // queue.
+    mProcessSecondaryQueueRunnable =
+      mSecondaryQueue->HasPendingEvent(aProofOfLock);
+
+    if (*aEvent) {
+      // We got an event, return early.
+      return retVal;
+    }
+  } while(aMayWait || mProcessSecondaryQueueRunnable);
+
+  return retVal;
+}
+
+//-----------------------------------------------------------------------------
+// nsIEventTarget
+
+NS_IMETHODIMP
+nsThread::DispatchFromScript(nsIRunnable* aEvent, uint32_t aFlags)
+{
+  nsCOMPtr<nsIRunnable> event(aEvent);
+  return Dispatch(event.forget(), aFlags);
+}
+
+NS_IMETHODIMP
+nsThread::Dispatch(already_AddRefed<nsIRunnable> aEvent, uint32_t aFlags)
+{
+  LOG(("THRD(%p) Dispatch [%p %x]\n", this, /* XXX aEvent */nullptr, aFlags));
+
+  return DispatchInternal(Move(aEvent), aFlags, nullptr);
+}
+
+NS_IMETHODIMP
+nsThread::DelayedDispatch(already_AddRefed<nsIRunnable> aEvent, uint32_t aDelayMs)
+{
+  NS_ENSURE_TRUE(!!aDelayMs, NS_ERROR_UNEXPECTED);
+
+  RefPtr<DelayedRunnable> r = new DelayedRunnable(Move(do_AddRef(this)),
+                                                  Move(aEvent),
+                                                  aDelayMs);
+  nsresult rv = r->Init();
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return DispatchInternal(r.forget(), 0, nullptr);
+}
+
+NS_IMETHODIMP
+nsThread::IsOnCurrentThread(bool* aResult)
+{
+  *aResult = (PR_GetCurrentThread() == mThread);
+  return NS_OK;
+}
+
+//-----------------------------------------------------------------------------
+// nsIThread
+
+NS_IMETHODIMP
+nsThread::GetPRThread(PRThread** aResult)
+{
+  *aResult = mThread;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThread::GetCanInvokeJS(bool* aResult)
+{
+  *aResult = mCanInvokeJS;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThread::SetCanInvokeJS(bool aCanInvokeJS)
+{
+  mCanInvokeJS = aCanInvokeJS;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThread::AsyncShutdown()
+{
+  LOG(("THRD(%p) async shutdown\n", this));
+
+  // XXX If we make this warn, then we hit that warning at xpcom shutdown while
+  //     shutting down a thread in a thread pool.  That happens b/c the thread
+  //     in the thread pool is already shutdown by the thread manager.
+  if (!mThread) {
+    return NS_OK;
+  }
+
+  return !!ShutdownInternal(/* aSync = */ false) ? NS_OK : NS_ERROR_UNEXPECTED;
+}
+
+nsThreadShutdownContext*
+nsThread::ShutdownInternal(bool aSync)
+{
+  MOZ_ASSERT(mThread);
+  MOZ_ASSERT(mThread != PR_GetCurrentThread());
+  if (NS_WARN_IF(mThread == PR_GetCurrentThread())) {
+    return nullptr;
+  }
+
+  // Prevent multiple calls to this method
+  {
+    MutexAutoLock lock(mLock);
+    if (!mShutdownRequired) {
+      return nullptr;
+    }
+    mShutdownRequired = false;
+  }
+
+  NotNull<nsThread*> currentThread =
+    WrapNotNull(nsThreadManager::get().GetCurrentThread());
+
+  nsAutoPtr<nsThreadShutdownContext>& context =
+    *currentThread->mRequestedShutdownContexts.AppendElement();
+  context = new nsThreadShutdownContext(WrapNotNull(this), currentThread, aSync);
+
+  // Set mShutdownContext and wake up the thread in case it is waiting for
+  // events to process.
+  nsCOMPtr<nsIRunnable> event =
+    new nsThreadShutdownEvent(WrapNotNull(this), WrapNotNull(context.get()));
+  // XXXroc What if posting the event fails due to OOM?
+  PutEvent(event.forget(), nullptr);
+
+  // We could still end up with other events being added after the shutdown
+  // task, but that's okay because we process pending events in ThreadFunc
+  // after setting mShutdownContext just before exiting.
+  return context;
+}
+
+void
+nsThread::ShutdownComplete(NotNull<nsThreadShutdownContext*> aContext)
+{
+  MOZ_ASSERT(mThread);
+  MOZ_ASSERT(aContext->mTerminatingThread == this);
+
+  if (aContext->mAwaitingShutdownAck) {
+    // We're in a synchronous shutdown, so tell whatever is up the stack that
+    // we're done and unwind the stack so it can call us again.
+    aContext->mAwaitingShutdownAck = false;
+    return;
+  }
+
+  // Now, it should be safe to join without fear of dead-locking.
+
+  PR_JoinThread(mThread);
+  mThread = nullptr;
+
+  // We hold strong references to our event observers, and once the thread is
+  // shut down the observers can't easily unregister themselves. Do it here
+  // to avoid leaking.
+  ClearObservers();
+
+#ifdef DEBUG
+  {
+    MutexAutoLock lock(mLock);
+    MOZ_ASSERT(!mObserver, "Should have been cleared at shutdown!");
+  }
+#endif
+
+  // Delete aContext.
+  MOZ_ALWAYS_TRUE(
+    aContext->mJoiningThread->mRequestedShutdownContexts.RemoveElement(aContext));
+}
+
+void
+nsThread::WaitForAllAsynchronousShutdowns()
+{
+  while (mRequestedShutdownContexts.Length()) {
+    NS_ProcessNextEvent(this, true);
+  }
+}
+
+NS_IMETHODIMP
+nsThread::Shutdown()
+{
+  LOG(("THRD(%p) sync shutdown\n", this));
+
+  // XXX If we make this warn, then we hit that warning at xpcom shutdown while
+  //     shutting down a thread in a thread pool.  That happens b/c the thread
+  //     in the thread pool is already shutdown by the thread manager.
+  if (!mThread) {
+    return NS_OK;
+  }
+
+  nsThreadShutdownContext* maybeContext = ShutdownInternal(/* aSync = */ true);
+  NS_ENSURE_TRUE(maybeContext, NS_ERROR_UNEXPECTED);
+  NotNull<nsThreadShutdownContext*> context = WrapNotNull(maybeContext);
+
+  // Process events on the current thread until we receive a shutdown ACK.
+  // Allows waiting; ensure no locks are held that would deadlock us!
+  while (context->mAwaitingShutdownAck) {
+    NS_ProcessNextEvent(context->mJoiningThread, true);
+  }
+
+  ShutdownComplete(context);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThread::HasPendingEvents(bool* aResult)
+{
+  if (NS_WARN_IF(PR_GetCurrentThread() != mThread)) {
+    return NS_ERROR_NOT_SAME_THREAD;
+  }
+
+  {
+    MutexAutoLock lock(mLock);
+    *aResult = mEvents->HasPendingEvent(lock);
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThread::RegisterIdlePeriod(already_AddRefed<nsIIdlePeriod> aIdlePeriod)
+{
+  if (NS_WARN_IF(PR_GetCurrentThread() != mThread)) {
+    return NS_ERROR_NOT_SAME_THREAD;
+  }
+
+  MutexAutoLock lock(mLock);
+  mIdlePeriod = aIdlePeriod;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThread::IdleDispatch(already_AddRefed<nsIRunnable> aEvent)
+{
+  // Currently the only supported idle dispatch is from the same
+  // thread. To support idle dispatch from another thread we need to
+  // support waking threads that are waiting for an event queue that
+  // isn't mIdleEvents.
+  MOZ_ASSERT(PR_GetCurrentThread() == mThread);
+
+  MutexAutoLock lock(mLock);
+  LeakRefPtr<nsIRunnable> event(Move(aEvent));
+
+  if (NS_WARN_IF(!event)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  if (mEventsAreDoomed) {
+    NS_WARNING("An idle event was posted to a thread that will never run it (rejected)");
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  mIdleEvents.PutEvent(event.take(), lock);
+  return NS_OK;
+}
+
+#ifdef MOZ_CANARY
+void canary_alarm_handler(int signum);
+
+class Canary
+{
+  //XXX ToDo: support nested loops
+public:
+  Canary()
+  {
+    if (sCanaryOutputFD > 0 && EventLatencyIsImportant()) {
+      signal(SIGALRM, canary_alarm_handler);
+      ualarm(15000, 0);
+    }
+  }
+
+  ~Canary()
+  {
+    if (sCanaryOutputFD != 0 && EventLatencyIsImportant()) {
+      ualarm(0, 0);
+    }
+  }
+
+  static bool EventLatencyIsImportant()
+  {
+    return NS_IsMainThread() && XRE_IsParentProcess();
+  }
+};
+
+void canary_alarm_handler(int signum)
+{
+  void* array[30];
+  const char msg[29] = "event took too long to run:\n";
+  // use write to be safe in the signal handler
+  write(sCanaryOutputFD, msg, sizeof(msg));
+  backtrace_symbols_fd(array, backtrace(array, 30), sCanaryOutputFD);
+}
+
+#endif
+
+#define NOTIFY_EVENT_OBSERVERS(func_, params_)                                 \
+  PR_BEGIN_MACRO                                                               \
+    if (!mEventObservers.IsEmpty()) {                                          \
+      nsAutoTObserverArray<NotNull<nsCOMPtr<nsIThreadObserver>>, 2>::ForwardIterator \
+        iter_(mEventObservers);                                                \
+      nsCOMPtr<nsIThreadObserver> obs_;                                        \
+      while (iter_.HasMore()) {                                                \
+        obs_ = iter_.GetNext();                                                \
+        obs_ -> func_ params_ ;                                                \
+      }                                                                        \
+    }                                                                          \
+  PR_END_MACRO
+
+void
+nsThread::GetIdleEvent(nsIRunnable** aEvent, MutexAutoLock& aProofOfLock)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == mThread);
+  MOZ_ASSERT(aEvent);
+
+  TimeStamp idleDeadline;
+  {
+    MutexAutoUnlock unlock(mLock);
+    mIdlePeriod->GetIdlePeriodHint(&idleDeadline);
+  }
+
+  if (!idleDeadline || idleDeadline < TimeStamp::Now()) {
+    aEvent = nullptr;
+    return;
+  }
+
+  mIdleEvents.GetEvent(false, aEvent, aProofOfLock);
+
+  if (*aEvent) {
+    nsCOMPtr<nsIIncrementalRunnable> incrementalEvent(do_QueryInterface(*aEvent));
+    if (incrementalEvent) {
+      incrementalEvent->SetDeadline(idleDeadline);
+    }
+  }
+}
+
+void
+nsThread::GetEvent(bool aWait, nsIRunnable** aEvent, MutexAutoLock& aProofOfLock)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == mThread);
+  MOZ_ASSERT(aEvent);
+
+  // We'll try to get an event to execute in three stages.
+  // [1] First we just try to get it from the regular queue without waiting.
+  mEvents->GetEvent(false, aEvent, aProofOfLock);
+
+  // [2] If we didn't get an event from the regular queue, try to
+  // get one from the idle queue
+  if (!*aEvent) {
+    // Since events in mEvents have higher priority than idle
+    // events, we will only consider idle events when there are no
+    // pending events in mEvents. We will for the same reason never
+    // wait for an idle event, since a higher priority event might
+    // appear at any time.
+    GetIdleEvent(aEvent, aProofOfLock);
+  }
+
+  // [3] If we neither got an event from the regular queue nor the
+  // idle queue, then if we should wait for events we block on the
+  // main queue until an event is available.
+  // If we are shutting down, then do not wait for new events.
+  if (!*aEvent && aWait) {
+    mEvents->GetEvent(aWait, aEvent, aProofOfLock);
+  }
+}
+
+NS_IMETHODIMP
+nsThread::ProcessNextEvent(bool aMayWait, bool* aResult)
+{
+  LOG(("THRD(%p) ProcessNextEvent [%u %u]\n", this, aMayWait,
+       mNestedEventLoopDepth));
+
+  if (NS_WARN_IF(PR_GetCurrentThread() != mThread)) {
+    return NS_ERROR_NOT_SAME_THREAD;
+  }
+
+  // The toplevel event loop normally blocks waiting for the next event, but
+  // if we're trying to shut this thread down, we must exit the event loop when
+  // the event queue is empty.
+  // This only applys to the toplevel event loop! Nested event loops (e.g.
+  // during sync dispatch) are waiting for some state change and must be able
+  // to block even if something has requested shutdown of the thread. Otherwise
+  // we'll just busywait as we endlessly look for an event, fail to find one,
+  // and repeat the nested event loop since its state change hasn't happened yet.
+  bool reallyWait = aMayWait && (mNestedEventLoopDepth > 0 || !ShuttingDown());
+
+  if (mIsMainThread == MAIN_THREAD) {
+    DoMainThreadSpecificProcessing(reallyWait);
+  }
+
+  ++mNestedEventLoopDepth;
+
+  // We only want to create an AutoNoJSAPI on threads that actually do DOM stuff
+  // (including workers).  Those are exactly the threads that have an
+  // mScriptObserver.
+  Maybe<dom::AutoNoJSAPI> noJSAPI;
+  bool callScriptObserver = !!mScriptObserver;
+  if (callScriptObserver) {
+    noJSAPI.emplace();
+    mScriptObserver->BeforeProcessTask(reallyWait);
+  }
+
+  nsCOMPtr<nsIThreadObserver> obs = mObserver;
+  if (obs) {
+    obs->OnProcessNextEvent(this, reallyWait);
+  }
+
+  NOTIFY_EVENT_OBSERVERS(OnProcessNextEvent, (this, reallyWait));
+
+#ifdef MOZ_CANARY
+  Canary canary;
+#endif
+  nsresult rv = NS_OK;
+
+  {
+    // Scope for |event| to make sure that its destructor fires while
+    // mNestedEventLoopDepth has been incremented, since that destructor can
+    // also do work.
+    nsCOMPtr<nsIRunnable> event;
+    {
+      MutexAutoLock lock(mLock);
+      GetEvent(reallyWait, getter_AddRefs(event), lock);
+    }
+
+    *aResult = (event.get() != nullptr);
+
+    if (event) {
+      LOG(("THRD(%p) running [%p]\n", this, event.get()));
+      if (MAIN_THREAD == mIsMainThread) {
+        HangMonitor::NotifyActivity();
+      }
+      event->Run();
+    } else if (aMayWait) {
+      MOZ_ASSERT(ShuttingDown(),
+                 "This should only happen when shutting down");
+      rv = NS_ERROR_UNEXPECTED;
+    }
+  }
+
+  NOTIFY_EVENT_OBSERVERS(AfterProcessNextEvent, (this, *aResult));
+
+  if (obs) {
+    obs->AfterProcessNextEvent(this, *aResult);
+  }
+
+  if (callScriptObserver) {
+    if (mScriptObserver) {
+      mScriptObserver->AfterProcessTask(mNestedEventLoopDepth);
+    }
+    noJSAPI.reset();
+  }
+
+  --mNestedEventLoopDepth;
+
+  return rv;
+}
+
+//-----------------------------------------------------------------------------
+// nsISupportsPriority
+
+NS_IMETHODIMP
+nsThread::GetPriority(int32_t* aPriority)
+{
+  *aPriority = mPriority;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThread::SetPriority(int32_t aPriority)
+{
+  if (NS_WARN_IF(!mThread)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  // NSPR defines the following four thread priorities:
+  //   PR_PRIORITY_LOW
+  //   PR_PRIORITY_NORMAL
+  //   PR_PRIORITY_HIGH
+  //   PR_PRIORITY_URGENT
+  // We map the priority values defined on nsISupportsPriority to these values.
+
+  mPriority = aPriority;
+
+  PRThreadPriority pri;
+  if (mPriority <= PRIORITY_HIGHEST) {
+    pri = PR_PRIORITY_URGENT;
+  } else if (mPriority < PRIORITY_NORMAL) {
+    pri = PR_PRIORITY_HIGH;
+  } else if (mPriority > PRIORITY_NORMAL) {
+    pri = PR_PRIORITY_LOW;
+  } else {
+    pri = PR_PRIORITY_NORMAL;
+  }
+  // If chaos mode is active, retain the randomly chosen priority
+  if (!ChaosMode::isActive(ChaosFeature::ThreadScheduling)) {
+    PR_SetThreadPriority(mThread, pri);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThread::AdjustPriority(int32_t aDelta)
+{
+  return SetPriority(mPriority + aDelta);
+}
+
+//-----------------------------------------------------------------------------
+// nsIThreadInternal
+
+NS_IMETHODIMP
+nsThread::GetObserver(nsIThreadObserver** aObs)
+{
+  MutexAutoLock lock(mLock);
+  NS_IF_ADDREF(*aObs = mObserver);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThread::SetObserver(nsIThreadObserver* aObs)
+{
+  if (NS_WARN_IF(PR_GetCurrentThread() != mThread)) {
+    return NS_ERROR_NOT_SAME_THREAD;
+  }
+
+  MutexAutoLock lock(mLock);
+  mObserver = aObs;
+  return NS_OK;
+}
+
+uint32_t
+nsThread::RecursionDepth() const
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == mThread);
+  return mNestedEventLoopDepth;
+}
+
+NS_IMETHODIMP
+nsThread::AddObserver(nsIThreadObserver* aObserver)
+{
+  if (NS_WARN_IF(!aObserver)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  if (NS_WARN_IF(PR_GetCurrentThread() != mThread)) {
+    return NS_ERROR_NOT_SAME_THREAD;
+  }
+
+  NS_WARNING_ASSERTION(!mEventObservers.Contains(aObserver),
+                       "Adding an observer twice!");
+
+  if (!mEventObservers.AppendElement(WrapNotNull(aObserver))) {
+    NS_WARNING("Out of memory!");
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThread::RemoveObserver(nsIThreadObserver* aObserver)
+{
+  if (NS_WARN_IF(PR_GetCurrentThread() != mThread)) {
+    return NS_ERROR_NOT_SAME_THREAD;
+  }
+
+  if (aObserver && !mEventObservers.RemoveElement(aObserver)) {
+    NS_WARNING("Removing an observer that was never added!");
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThread::PushEventQueue(nsIEventTarget** aResult)
+{
+  if (NS_WARN_IF(PR_GetCurrentThread() != mThread)) {
+    return NS_ERROR_NOT_SAME_THREAD;
+  }
+
+  NotNull<nsChainedEventQueue*> queue =
+    WrapNotNull(new nsChainedEventQueue(mLock));
+  queue->mEventTarget = new nsNestedEventTarget(WrapNotNull(this), queue);
+
+  {
+    MutexAutoLock lock(mLock);
+    queue->mNext = mEvents;
+    mEvents = queue;
+  }
+
+  NS_ADDREF(*aResult = queue->mEventTarget);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThread::PopEventQueue(nsIEventTarget* aInnermostTarget)
+{
+  if (NS_WARN_IF(PR_GetCurrentThread() != mThread)) {
+    return NS_ERROR_NOT_SAME_THREAD;
+  }
+
+  if (NS_WARN_IF(!aInnermostTarget)) {
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  // Don't delete or release anything while holding the lock.
+  nsAutoPtr<nsChainedEventQueue> queue;
+  RefPtr<nsNestedEventTarget> target;
+
+  {
+    MutexAutoLock lock(mLock);
+
+    // Make sure we're popping the innermost event target.
+    if (NS_WARN_IF(mEvents->mEventTarget != aInnermostTarget)) {
+      return NS_ERROR_UNEXPECTED;
+    }
+
+    MOZ_ASSERT(mEvents != &mEventsRoot);
+
+    queue = mEvents;
+    mEvents = WrapNotNull(mEvents->mNext);
+
+    nsCOMPtr<nsIRunnable> event;
+    while (queue->GetEvent(false, getter_AddRefs(event), lock)) {
+      mEvents->PutEvent(event.forget(), lock);
+    }
+
+    // Don't let the event target post any more events.
+    queue->mEventTarget.swap(target);
+    target->mQueue = nullptr;
+  }
+
+  return NS_OK;
+}
+
+void
+nsThread::SetScriptObserver(mozilla::CycleCollectedJSContext* aScriptObserver)
+{
+  if (!aScriptObserver) {
+    mScriptObserver = nullptr;
+    return;
+  }
+
+  MOZ_ASSERT(!mScriptObserver);
+  mScriptObserver = aScriptObserver;
+}
+
+void
+nsThread::DoMainThreadSpecificProcessing(bool aReallyWait)
+{
+  MOZ_ASSERT(mIsMainThread == MAIN_THREAD);
+
+  ipc::CancelCPOWs();
+
+  if (aReallyWait) {
+    HangMonitor::Suspend();
+  }
+
+  // Fire a memory pressure notification, if one is pending.
+  if (!ShuttingDown()) {
+    MemoryPressureState mpPending = NS_GetPendingMemoryPressure();
+    if (mpPending != MemPressure_None) {
+      nsCOMPtr<nsIObserverService> os = services::GetObserverService();
+
+      // Use no-forward to prevent the notifications from being transferred to
+      // the children of this process.
+      NS_NAMED_LITERAL_STRING(lowMem, "low-memory-no-forward");
+      NS_NAMED_LITERAL_STRING(lowMemOngoing, "low-memory-ongoing-no-forward");
+
+      if (os) {
+        os->NotifyObservers(nullptr, "memory-pressure",
+                            mpPending == MemPressure_New ? lowMem.get() :
+                            lowMemOngoing.get());
+      } else {
+        NS_WARNING("Can't get observer service!");
+      }
+    }
+  }
+
+#ifdef MOZ_CRASHREPORTER
+  if (!ShuttingDown()) {
+    SaveMemoryReportNearOOM(ShouldSaveMemoryReport::kMaybeReport);
+  }
+#endif
+}
+
+//-----------------------------------------------------------------------------
+
+NS_IMPL_ISUPPORTS(nsThread::nsNestedEventTarget, nsIEventTarget)
+
+NS_IMETHODIMP
+nsThread::nsNestedEventTarget::DispatchFromScript(nsIRunnable* aEvent, uint32_t aFlags)
+{
+  nsCOMPtr<nsIRunnable> event(aEvent);
+  return Dispatch(event.forget(), aFlags);
+}
+
+NS_IMETHODIMP
+nsThread::nsNestedEventTarget::Dispatch(already_AddRefed<nsIRunnable> aEvent, uint32_t aFlags)
+{
+  LOG(("THRD(%p) Dispatch [%p %x] to nested loop %p\n", mThread.get().get(),
+       /*XXX aEvent*/ nullptr, aFlags, this));
+
+  return mThread->DispatchInternal(Move(aEvent), aFlags, this);
+}
+
+NS_IMETHODIMP
+nsThread::nsNestedEventTarget::DelayedDispatch(already_AddRefed<nsIRunnable>, uint32_t)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsThread::nsNestedEventTarget::IsOnCurrentThread(bool* aResult)
+{
+  return mThread->IsOnCurrentThread(aResult);
+}
diff --git a/xpcom/threads/nsThread.h b/xpcom/threads/nsThread.h
new file mode 100644
index 000000000..836123747
--- /dev/null
+++ b/xpcom/threads/nsThread.h
@@ -0,0 +1,284 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsThread_h__
+#define nsThread_h__
+
+#include "mozilla/Mutex.h"
+#include "nsIIdlePeriod.h"
+#include "nsIThreadInternal.h"
+#include "nsISupportsPriority.h"
+#include "nsEventQueue.h"
+#include "nsThreadUtils.h"
+#include "nsString.h"
+#include "nsTObserverArray.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/NotNull.h"
+#include "nsAutoPtr.h"
+#include "mozilla/AlreadyAddRefed.h"
+#include "mozilla/UniquePtr.h"
+
+namespace mozilla {
+class CycleCollectedJSContext;
+}
+
+using mozilla::NotNull;
+
+// A native thread
+class nsThread
+  : public nsIThreadInternal
+  , public nsISupportsPriority
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIEVENTTARGET
+  NS_DECL_NSITHREAD
+  NS_DECL_NSITHREADINTERNAL
+  NS_DECL_NSISUPPORTSPRIORITY
+  using nsIEventTarget::Dispatch;
+
+  enum MainThreadFlag
+  {
+    MAIN_THREAD,
+    NOT_MAIN_THREAD
+  };
+
+  nsThread(MainThreadFlag aMainThread, uint32_t aStackSize);
+
+  // Initialize this as a wrapper for a new PRThread.
+  nsresult Init();
+
+  // Initialize this as a wrapper for the current PRThread.
+  nsresult InitCurrentThread();
+
+  // The PRThread corresponding to this thread.
+  PRThread* GetPRThread()
+  {
+    return mThread;
+  }
+
+  // If this flag is true, then the nsThread was created using
+  // nsIThreadManager::NewThread.
+  bool ShutdownRequired()
+  {
+    return mShutdownRequired;
+  }
+
+  // Clear the observer list.
+  void ClearObservers()
+  {
+    mEventObservers.Clear();
+  }
+
+  void
+  SetScriptObserver(mozilla::CycleCollectedJSContext* aScriptObserver);
+
+  uint32_t
+  RecursionDepth() const;
+
+  void ShutdownComplete(NotNull<struct nsThreadShutdownContext*> aContext);
+
+  void WaitForAllAsynchronousShutdowns();
+
+#ifdef MOZ_CRASHREPORTER
+  enum class ShouldSaveMemoryReport
+  {
+    kMaybeReport,
+    kForceReport
+  };
+
+  static bool SaveMemoryReportNearOOM(ShouldSaveMemoryReport aShouldSave);
+#endif
+
+private:
+  void DoMainThreadSpecificProcessing(bool aReallyWait);
+
+  void GetIdleEvent(nsIRunnable** aEvent, mozilla::MutexAutoLock& aProofOfLock);
+  void GetEvent(bool aWait, nsIRunnable** aEvent,
+                mozilla::MutexAutoLock& aProofOfLock);
+
+protected:
+  class nsChainedEventQueue;
+
+  class nsNestedEventTarget;
+  friend class nsNestedEventTarget;
+
+  friend class nsThreadShutdownEvent;
+
+  virtual ~nsThread();
+
+  bool ShuttingDown()
+  {
+    return mShutdownContext != nullptr;
+  }
+
+  static void ThreadFunc(void* aArg);
+
+  // Helper
+  already_AddRefed<nsIThreadObserver> GetObserver()
+  {
+    nsIThreadObserver* obs;
+    nsThread::GetObserver(&obs);
+    return already_AddRefed<nsIThreadObserver>(obs);
+  }
+
+  // Wrappers for event queue methods:
+  nsresult PutEvent(nsIRunnable* aEvent, nsNestedEventTarget* aTarget);
+  nsresult PutEvent(already_AddRefed<nsIRunnable> aEvent,
+                    nsNestedEventTarget* aTarget);
+
+  nsresult DispatchInternal(already_AddRefed<nsIRunnable> aEvent,
+                            uint32_t aFlags, nsNestedEventTarget* aTarget);
+
+  struct nsThreadShutdownContext* ShutdownInternal(bool aSync);
+
+  // Wrapper for nsEventQueue that supports chaining.
+  class nsChainedEventQueue
+  {
+  public:
+    explicit nsChainedEventQueue(mozilla::Mutex& aLock)
+      : mNext(nullptr)
+      , mEventsAvailable(aLock, "[nsChainedEventQueue.mEventsAvailable]")
+      , mProcessSecondaryQueueRunnable(false)
+    {
+      mNormalQueue =
+        mozilla::MakeUnique<nsEventQueue>(mEventsAvailable,
+                                          nsEventQueue::eSharedCondVarQueue);
+      // Both queues need to use the same CondVar!
+      mSecondaryQueue =
+        mozilla::MakeUnique<nsEventQueue>(mEventsAvailable,
+                                          nsEventQueue::eSharedCondVarQueue);
+    }
+
+    bool GetEvent(bool aMayWait, nsIRunnable** aEvent,
+                  mozilla::MutexAutoLock& aProofOfLock);
+
+    void PutEvent(nsIRunnable* aEvent, mozilla::MutexAutoLock& aProofOfLock)
+    {
+      RefPtr<nsIRunnable> event(aEvent);
+      PutEvent(event.forget(), aProofOfLock);
+    }
+
+    void PutEvent(already_AddRefed<nsIRunnable> aEvent,
+                  mozilla::MutexAutoLock& aProofOfLock)
+    {
+      RefPtr<nsIRunnable> event(aEvent);
+      nsCOMPtr<nsIRunnablePriority> runnablePrio =
+        do_QueryInterface(event);
+      uint32_t prio = nsIRunnablePriority::PRIORITY_NORMAL;
+      if (runnablePrio) {
+        runnablePrio->GetPriority(&prio);
+      }
+      MOZ_ASSERT(prio == nsIRunnablePriority::PRIORITY_NORMAL ||
+                 prio == nsIRunnablePriority::PRIORITY_HIGH);
+      if (prio == nsIRunnablePriority::PRIORITY_NORMAL) {
+        mNormalQueue->PutEvent(event.forget(), aProofOfLock);
+      } else {
+        mSecondaryQueue->PutEvent(event.forget(), aProofOfLock);
+      }
+    }
+
+    bool HasPendingEvent(mozilla::MutexAutoLock& aProofOfLock)
+    {
+      return mNormalQueue->HasPendingEvent(aProofOfLock) ||
+             mSecondaryQueue->HasPendingEvent(aProofOfLock);
+    }
+
+    nsChainedEventQueue* mNext;
+    RefPtr<nsNestedEventTarget> mEventTarget;
+
+  private:
+    mozilla::CondVar mEventsAvailable;
+    mozilla::UniquePtr<nsEventQueue> mNormalQueue;
+    mozilla::UniquePtr<nsEventQueue> mSecondaryQueue;
+
+    // Try to process one high priority runnable after each normal
+    // priority runnable. This gives the processing model HTML spec has for
+    // 'Update the rendering' in the case only vsync messages are in the
+    // secondary queue and prevents starving the normal queue.
+    bool mProcessSecondaryQueueRunnable;
+  };
+
+  class nsNestedEventTarget final : public nsIEventTarget
+  {
+  public:
+    NS_DECL_THREADSAFE_ISUPPORTS
+    NS_DECL_NSIEVENTTARGET
+
+    nsNestedEventTarget(NotNull<nsThread*> aThread,
+                        NotNull<nsChainedEventQueue*> aQueue)
+      : mThread(aThread)
+      , mQueue(aQueue)
+
+
+
+    {
+    }
+
+    NotNull<RefPtr<nsThread>> mThread;
+
+    // This is protected by mThread->mLock.
+    nsChainedEventQueue* mQueue;
+
+  private:
+    ~nsNestedEventTarget()
+    {
+    }
+  };
+
+  // This lock protects access to mObserver, mEvents, mIdleEvents,
+  // mIdlePeriod and mEventsAreDoomed.  All of those fields are only
+  // modified on the thread itself (never from another thread).  This
+  // means that we can avoid holding the lock while using mObserver
+  // and mEvents on the thread itself.  When calling PutEvent on
+  // mEvents, we have to hold the lock to synchronize with
+  // PopEventQueue.
+  mozilla::Mutex mLock;
+
+  nsCOMPtr<nsIThreadObserver> mObserver;
+  mozilla::CycleCollectedJSContext* mScriptObserver;
+
+  // Only accessed on the target thread.
+  nsAutoTObserverArray<NotNull<nsCOMPtr<nsIThreadObserver>>, 2> mEventObservers;
+
+  NotNull<nsChainedEventQueue*> mEvents;  // never null
+  nsChainedEventQueue mEventsRoot;
+
+  // mIdlePeriod keeps track of the current idle period. If at any
+  // time the main event queue is empty, calling
+  // mIdlePeriod->GetIdlePeriodHint() will give an estimate of when
+  // the current idle period will end.
+  nsCOMPtr<nsIIdlePeriod> mIdlePeriod;
+  mozilla::CondVar mIdleEventsAvailable;
+  nsEventQueue mIdleEvents;
+
+  int32_t   mPriority;
+  PRThread* mThread;
+  uint32_t  mNestedEventLoopDepth;
+  uint32_t  mStackSize;
+
+  // The shutdown context for ourselves.
+  struct nsThreadShutdownContext* mShutdownContext;
+  // The shutdown contexts for any other threads we've asked to shut down.
+  nsTArray<nsAutoPtr<struct nsThreadShutdownContext>> mRequestedShutdownContexts;
+
+  bool mShutdownRequired;
+  // Set to true when events posted to this thread will never run.
+  bool mEventsAreDoomed;
+  MainThreadFlag mIsMainThread;
+
+  // Set to true if this thread creates a JSRuntime.
+  bool mCanInvokeJS;
+};
+
+#if defined(XP_UNIX) && !defined(ANDROID) && !defined(DEBUG) && HAVE_UALARM \
+  && defined(_GNU_SOURCE)
+# define MOZ_CANARY
+
+extern int sCanaryOutputFD;
+#endif
+
+#endif  // nsThread_h__
diff --git a/xpcom/threads/nsThreadManager.cpp b/xpcom/threads/nsThreadManager.cpp
new file mode 100644
index 000000000..d1eb84b8f
--- /dev/null
+++ b/xpcom/threads/nsThreadManager.cpp
@@ -0,0 +1,342 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsThreadManager.h"
+#include "nsThread.h"
+#include "nsThreadUtils.h"
+#include "nsIClassInfoImpl.h"
+#include "nsTArray.h"
+#include "nsAutoPtr.h"
+#include "mozilla/ThreadLocal.h"
+#ifdef MOZ_CANARY
+#include <fcntl.h>
+#include <unistd.h>
+#endif
+
+#include "MainThreadIdlePeriod.h"
+
+using namespace mozilla;
+
+static MOZ_THREAD_LOCAL(bool) sTLSIsMainThread;
+
+bool
+NS_IsMainThread()
+{
+  return sTLSIsMainThread.get();
+}
+
+void
+NS_SetMainThread()
+{
+  if (!sTLSIsMainThread.init()) {
+    MOZ_CRASH();
+  }
+  sTLSIsMainThread.set(true);
+  MOZ_ASSERT(NS_IsMainThread());
+}
+
+typedef nsTArray<NotNull<RefPtr<nsThread>>> nsThreadArray;
+
+//-----------------------------------------------------------------------------
+
+static void
+ReleaseObject(void* aData)
+{
+  static_cast<nsISupports*>(aData)->Release();
+}
+
+// statically allocated instance
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsThreadManager::AddRef()
+{
+  return 2;
+}
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsThreadManager::Release()
+{
+  return 1;
+}
+NS_IMPL_CLASSINFO(nsThreadManager, nullptr,
+                  nsIClassInfo::THREADSAFE | nsIClassInfo::SINGLETON,
+                  NS_THREADMANAGER_CID)
+NS_IMPL_QUERY_INTERFACE_CI(nsThreadManager, nsIThreadManager)
+NS_IMPL_CI_INTERFACE_GETTER(nsThreadManager, nsIThreadManager)
+
+//-----------------------------------------------------------------------------
+
+nsresult
+nsThreadManager::Init()
+{
+  // Child processes need to initialize the thread manager before they
+  // initialize XPCOM in order to set up the crash reporter. This leads to
+  // situations where we get initialized twice.
+  if (mInitialized) {
+    return NS_OK;
+  }
+
+  if (PR_NewThreadPrivateIndex(&mCurThreadIndex, ReleaseObject) == PR_FAILURE) {
+    return NS_ERROR_FAILURE;
+  }
+
+
+#ifdef MOZ_CANARY
+  const int flags = O_WRONLY | O_APPEND | O_CREAT | O_NONBLOCK;
+  const mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
+  char* env_var_flag = getenv("MOZ_KILL_CANARIES");
+  sCanaryOutputFD =
+    env_var_flag ? (env_var_flag[0] ? open(env_var_flag, flags, mode) :
+                                      STDERR_FILENO) :
+                   0;
+#endif
+
+  // Setup "main" thread
+  mMainThread = new nsThread(nsThread::MAIN_THREAD, 0);
+
+  nsresult rv = mMainThread->InitCurrentThread();
+  if (NS_FAILED(rv)) {
+    mMainThread = nullptr;
+    return rv;
+  }
+
+  {
+    nsCOMPtr<nsIIdlePeriod> idlePeriod = new MainThreadIdlePeriod();
+    mMainThread->RegisterIdlePeriod(idlePeriod.forget());
+  }
+
+  // We need to keep a pointer to the current thread, so we can satisfy
+  // GetIsMainThread calls that occur post-Shutdown.
+  mMainThread->GetPRThread(&mMainPRThread);
+
+  mInitialized = true;
+  return NS_OK;
+}
+
+void
+nsThreadManager::Shutdown()
+{
+  MOZ_ASSERT(NS_IsMainThread(), "shutdown not called from main thread");
+
+  // Prevent further access to the thread manager (no more new threads!)
+  //
+  // What happens if shutdown happens before NewThread completes?
+  // We Shutdown() the new thread, and return error if we've started Shutdown
+  // between when NewThread started, and when the thread finished initializing
+  // and registering with ThreadManager.
+  //
+  mInitialized = false;
+
+  // Empty the main thread event queue before we begin shutting down threads.
+  NS_ProcessPendingEvents(mMainThread);
+
+  // We gather the threads from the hashtable into a list, so that we avoid
+  // holding the hashtable lock while calling nsIThread::Shutdown.
+  nsThreadArray threads;
+  {
+    OffTheBooksMutexAutoLock lock(mLock);
+    for (auto iter = mThreadsByPRThread.Iter(); !iter.Done(); iter.Next()) {
+      RefPtr<nsThread>& thread = iter.Data();
+      threads.AppendElement(WrapNotNull(thread));
+      iter.Remove();
+    }
+  }
+
+  // It's tempting to walk the list of threads here and tell them each to stop
+  // accepting new events, but that could lead to badness if one of those
+  // threads is stuck waiting for a response from another thread.  To do it
+  // right, we'd need some way to interrupt the threads.
+  //
+  // Instead, we process events on the current thread while waiting for threads
+  // to shutdown.  This means that we have to preserve a mostly functioning
+  // world until such time as the threads exit.
+
+  // Shutdown all threads that require it (join with threads that we created).
+  for (uint32_t i = 0; i < threads.Length(); ++i) {
+    NotNull<nsThread*> thread = threads[i];
+    if (thread->ShutdownRequired()) {
+      thread->Shutdown();
+    }
+  }
+
+  // NB: It's possible that there are events in the queue that want to *start*
+  // an asynchronous shutdown. But we have already shutdown the threads above,
+  // so there's no need to worry about them. We only have to wait for all
+  // in-flight asynchronous thread shutdowns to complete.
+  mMainThread->WaitForAllAsynchronousShutdowns();
+
+  // In case there are any more events somehow...
+  NS_ProcessPendingEvents(mMainThread);
+
+  // There are no more background threads at this point.
+
+  // Clear the table of threads.
+  {
+    OffTheBooksMutexAutoLock lock(mLock);
+    mThreadsByPRThread.Clear();
+  }
+
+  // Normally thread shutdown clears the observer for the thread, but since the
+  // main thread is special we do it manually here after we're sure all events
+  // have been processed.
+  mMainThread->SetObserver(nullptr);
+  mMainThread->ClearObservers();
+
+  // Release main thread object.
+  mMainThread = nullptr;
+
+  // Remove the TLS entry for the main thread.
+  PR_SetThreadPrivate(mCurThreadIndex, nullptr);
+}
+
+void
+nsThreadManager::RegisterCurrentThread(nsThread& aThread)
+{
+  MOZ_ASSERT(aThread.GetPRThread() == PR_GetCurrentThread(), "bad aThread");
+
+  OffTheBooksMutexAutoLock lock(mLock);
+
+  ++mCurrentNumberOfThreads;
+  if (mCurrentNumberOfThreads > mHighestNumberOfThreads) {
+    mHighestNumberOfThreads = mCurrentNumberOfThreads;
+  }
+
+  mThreadsByPRThread.Put(aThread.GetPRThread(), &aThread);  // XXX check OOM?
+
+  aThread.AddRef();  // for TLS entry
+  PR_SetThreadPrivate(mCurThreadIndex, &aThread);
+}
+
+void
+nsThreadManager::UnregisterCurrentThread(nsThread& aThread)
+{
+  MOZ_ASSERT(aThread.GetPRThread() == PR_GetCurrentThread(), "bad aThread");
+
+  OffTheBooksMutexAutoLock lock(mLock);
+
+  --mCurrentNumberOfThreads;
+  mThreadsByPRThread.Remove(aThread.GetPRThread());
+
+  PR_SetThreadPrivate(mCurThreadIndex, nullptr);
+  // Ref-count balanced via ReleaseObject
+}
+
+nsThread*
+nsThreadManager::GetCurrentThread()
+{
+  // read thread local storage
+  void* data = PR_GetThreadPrivate(mCurThreadIndex);
+  if (data) {
+    return static_cast<nsThread*>(data);
+  }
+
+  if (!mInitialized) {
+    return nullptr;
+  }
+
+  // OK, that's fine.  We'll dynamically create one :-)
+  RefPtr<nsThread> thread = new nsThread(nsThread::NOT_MAIN_THREAD, 0);
+  if (!thread || NS_FAILED(thread->InitCurrentThread())) {
+    return nullptr;
+  }
+
+  return thread.get();  // reference held in TLS
+}
+
+NS_IMETHODIMP
+nsThreadManager::NewThread(uint32_t aCreationFlags,
+                           uint32_t aStackSize,
+                           nsIThread** aResult)
+{
+  // Note: can be called from arbitrary threads
+  
+  // No new threads during Shutdown
+  if (NS_WARN_IF(!mInitialized)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  RefPtr<nsThread> thr = new nsThread(nsThread::NOT_MAIN_THREAD, aStackSize);
+  nsresult rv = thr->Init();  // Note: blocks until the new thread has been set up
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // At this point, we expect that the thread has been registered in mThreadByPRThread;
+  // however, it is possible that it could have also been replaced by now, so
+  // we cannot really assert that it was added.  Instead, kill it if we entered
+  // Shutdown() during/before Init()
+
+  if (NS_WARN_IF(!mInitialized)) {
+    if (thr->ShutdownRequired()) {
+      thr->Shutdown(); // ok if it happens multiple times
+    }
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  thr.forget(aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadManager::GetThreadFromPRThread(PRThread* aThread, nsIThread** aResult)
+{
+  // Keep this functioning during Shutdown
+  if (NS_WARN_IF(!mMainThread)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  if (NS_WARN_IF(!aThread)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  RefPtr<nsThread> temp;
+  {
+    OffTheBooksMutexAutoLock lock(mLock);
+    mThreadsByPRThread.Get(aThread, getter_AddRefs(temp));
+  }
+
+  NS_IF_ADDREF(*aResult = temp);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadManager::GetMainThread(nsIThread** aResult)
+{
+  // Keep this functioning during Shutdown
+  if (NS_WARN_IF(!mMainThread)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  NS_ADDREF(*aResult = mMainThread);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadManager::GetCurrentThread(nsIThread** aResult)
+{
+  // Keep this functioning during Shutdown
+  if (NS_WARN_IF(!mMainThread)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  *aResult = GetCurrentThread();
+  if (!*aResult) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  NS_ADDREF(*aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadManager::GetIsMainThread(bool* aResult)
+{
+  // This method may be called post-Shutdown
+
+  *aResult = (PR_GetCurrentThread() == mMainPRThread);
+  return NS_OK;
+}
+
+uint32_t
+nsThreadManager::GetHighestNumberOfThreads()
+{
+  OffTheBooksMutexAutoLock lock(mLock);
+  return mHighestNumberOfThreads;
+}
diff --git a/xpcom/threads/nsThreadManager.h b/xpcom/threads/nsThreadManager.h
new file mode 100644
index 000000000..64ccc9bc9
--- /dev/null
+++ b/xpcom/threads/nsThreadManager.h
@@ -0,0 +1,89 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsThreadManager_h__
+#define nsThreadManager_h__
+
+#include "mozilla/Mutex.h"
+#include "nsIThreadManager.h"
+#include "nsRefPtrHashtable.h"
+#include "nsThread.h"
+
+class nsIRunnable;
+
+class nsThreadManager : public nsIThreadManager
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSITHREADMANAGER
+
+  static nsThreadManager& get()
+  {
+    static nsThreadManager sInstance;
+    return sInstance;
+  }
+
+  nsresult Init();
+
+  // Shutdown all threads.  This function should only be called on the main
+  // thread of the application process.
+  void Shutdown();
+
+  // Called by nsThread to inform the ThreadManager it exists.  This method
+  // must be called when the given thread is the current thread.
+  void RegisterCurrentThread(nsThread& aThread);
+
+  // Called by nsThread to inform the ThreadManager it is going away.  This
+  // method must be called when the given thread is the current thread.
+  void UnregisterCurrentThread(nsThread& aThread);
+
+  // Returns the current thread.  Returns null if OOM or if ThreadManager isn't
+  // initialized.
+  nsThread* GetCurrentThread();
+
+  // Returns the maximal number of threads that have been in existence
+  // simultaneously during the execution of the thread manager.
+  uint32_t GetHighestNumberOfThreads();
+
+  // This needs to be public in order to support static instantiation of this
+  // class with older compilers (e.g., egcs-2.91.66).
+  ~nsThreadManager()
+  {
+  }
+
+private:
+  nsThreadManager()
+    : mCurThreadIndex(0)
+    , mMainPRThread(nullptr)
+    , mLock("nsThreadManager.mLock")
+    , mInitialized(false)
+    , mCurrentNumberOfThreads(1)
+    , mHighestNumberOfThreads(1)
+  {
+  }
+
+  nsRefPtrHashtable<nsPtrHashKey<PRThread>, nsThread> mThreadsByPRThread;
+  unsigned            mCurThreadIndex;  // thread-local-storage index
+  RefPtr<nsThread>  mMainThread;
+  PRThread*         mMainPRThread;
+  mozilla::OffTheBooksMutex mLock;  // protects tables
+  mozilla::Atomic<bool> mInitialized;
+
+  // The current number of threads
+  uint32_t            mCurrentNumberOfThreads;
+  // The highest number of threads encountered so far during the session
+  uint32_t            mHighestNumberOfThreads;
+};
+
+#define NS_THREADMANAGER_CID                       \
+{ /* 7a4204c6-e45a-4c37-8ebb-6709a22c917c */       \
+  0x7a4204c6,                                      \
+  0xe45a,                                          \
+  0x4c37,                                          \
+  {0x8e, 0xbb, 0x67, 0x09, 0xa2, 0x2c, 0x91, 0x7c} \
+}
+
+#endif  // nsThreadManager_h__
diff --git a/xpcom/threads/nsThreadPool.cpp b/xpcom/threads/nsThreadPool.cpp
new file mode 100644
index 000000000..241fad39d
--- /dev/null
+++ b/xpcom/threads/nsThreadPool.cpp
@@ -0,0 +1,449 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIClassInfoImpl.h"
+#include "nsThreadPool.h"
+#include "nsThreadManager.h"
+#include "nsThread.h"
+#include "nsMemory.h"
+#include "nsAutoPtr.h"
+#include "prinrval.h"
+#include "mozilla/Logging.h"
+#include "nsThreadSyncDispatch.h"
+
+using namespace mozilla;
+
+static LazyLogModule sThreadPoolLog("nsThreadPool");
+#ifdef LOG
+#undef LOG
+#endif
+#define LOG(args) MOZ_LOG(sThreadPoolLog, mozilla::LogLevel::Debug, args)
+
+// DESIGN:
+//  o  Allocate anonymous threads.
+//  o  Use nsThreadPool::Run as the main routine for each thread.
+//  o  Each thread waits on the event queue's monitor, checking for
+//     pending events and rescheduling itself as an idle thread.
+
+#define DEFAULT_THREAD_LIMIT 4
+#define DEFAULT_IDLE_THREAD_LIMIT 1
+#define DEFAULT_IDLE_THREAD_TIMEOUT PR_SecondsToInterval(60)
+
+NS_IMPL_ADDREF(nsThreadPool)
+NS_IMPL_RELEASE(nsThreadPool)
+NS_IMPL_CLASSINFO(nsThreadPool, nullptr, nsIClassInfo::THREADSAFE,
+                  NS_THREADPOOL_CID)
+NS_IMPL_QUERY_INTERFACE_CI(nsThreadPool, nsIThreadPool, nsIEventTarget,
+                           nsIRunnable)
+NS_IMPL_CI_INTERFACE_GETTER(nsThreadPool, nsIThreadPool, nsIEventTarget)
+
+nsThreadPool::nsThreadPool()
+  : mMutex("[nsThreadPool.mMutex]")
+  , mEventsAvailable(mMutex, "[nsThreadPool.mEventsAvailable]")
+  , mEvents(mEventsAvailable, nsEventQueue::eNormalQueue)
+  , mThreadLimit(DEFAULT_THREAD_LIMIT)
+  , mIdleThreadLimit(DEFAULT_IDLE_THREAD_LIMIT)
+  , mIdleThreadTimeout(DEFAULT_IDLE_THREAD_TIMEOUT)
+  , mIdleCount(0)
+  , mStackSize(nsIThreadManager::DEFAULT_STACK_SIZE)
+  , mShutdown(false)
+{
+  LOG(("THRD-P(%p) constructor!!!\n", this));
+}
+
+nsThreadPool::~nsThreadPool()
+{
+  // Threads keep a reference to the nsThreadPool until they return from Run()
+  // after removing themselves from mThreads.
+  MOZ_ASSERT(mThreads.IsEmpty());
+}
+
+nsresult
+nsThreadPool::PutEvent(nsIRunnable* aEvent)
+{
+  nsCOMPtr<nsIRunnable> event(aEvent);
+  return PutEvent(event.forget(), 0);
+}
+
+nsresult
+nsThreadPool::PutEvent(already_AddRefed<nsIRunnable> aEvent, uint32_t aFlags)
+{
+  // Avoid spawning a new thread while holding the event queue lock...
+
+  bool spawnThread = false;
+  uint32_t stackSize = 0;
+  {
+    MutexAutoLock lock(mMutex);
+
+    if (NS_WARN_IF(mShutdown)) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+    LOG(("THRD-P(%p) put [%d %d %d]\n", this, mIdleCount, mThreads.Count(),
+         mThreadLimit));
+    MOZ_ASSERT(mIdleCount <= (uint32_t)mThreads.Count(), "oops");
+
+    // Make sure we have a thread to service this event.
+    if (mThreads.Count() < (int32_t)mThreadLimit &&
+        !(aFlags & NS_DISPATCH_AT_END) &&
+        // Spawn a new thread if we don't have enough idle threads to serve
+        // pending events immediately.
+        mEvents.Count(lock) >= mIdleCount) {
+      spawnThread = true;
+    }
+
+    mEvents.PutEvent(Move(aEvent), lock);
+    stackSize = mStackSize;
+  }
+
+  LOG(("THRD-P(%p) put [spawn=%d]\n", this, spawnThread));
+  if (!spawnThread) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIThread> thread;
+  nsThreadManager::get().NewThread(0, stackSize, getter_AddRefs(thread));
+  if (NS_WARN_IF(!thread)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  bool killThread = false;
+  {
+    MutexAutoLock lock(mMutex);
+    if (mThreads.Count() < (int32_t)mThreadLimit) {
+      mThreads.AppendObject(thread);
+    } else {
+      killThread = true;  // okay, we don't need this thread anymore
+    }
+  }
+  LOG(("THRD-P(%p) put [%p kill=%d]\n", this, thread.get(), killThread));
+  if (killThread) {
+    // We never dispatched any events to the thread, so we can shut it down
+    // asynchronously without worrying about anything.
+    ShutdownThread(thread);
+  } else {
+    thread->Dispatch(this, NS_DISPATCH_NORMAL);
+  }
+
+  return NS_OK;
+}
+
+void
+nsThreadPool::ShutdownThread(nsIThread* aThread)
+{
+  LOG(("THRD-P(%p) shutdown async [%p]\n", this, aThread));
+
+  // This is either called by a threadpool thread that is out of work, or
+  // a thread that attempted to create a threadpool thread and raced in
+  // such a way that the newly created thread is no longer necessary.
+  // In the first case, we must go to another thread to shut aThread down
+  // (because it is the current thread).  In the second case, we cannot
+  // synchronously shut down the current thread (because then Dispatch() would
+  // spin the event loop, and that could blow up the world), and asynchronous
+  // shutdown requires this thread have an event loop (and it may not, see bug
+  // 10204784).  The simplest way to cover all cases is to asynchronously
+  // shutdown aThread from the main thread.
+  NS_DispatchToMainThread(NewRunnableMethod(aThread,
+                                            &nsIThread::AsyncShutdown));
+}
+
+NS_IMETHODIMP
+nsThreadPool::Run()
+{
+  mThreadNaming.SetThreadPoolName(mName);
+
+  LOG(("THRD-P(%p) enter %s\n", this, mName.BeginReading()));
+
+  nsCOMPtr<nsIThread> current;
+  nsThreadManager::get().GetCurrentThread(getter_AddRefs(current));
+
+  bool shutdownThreadOnExit = false;
+  bool exitThread = false;
+  bool wasIdle = false;
+  PRIntervalTime idleSince;
+
+  nsCOMPtr<nsIThreadPoolListener> listener;
+  {
+    MutexAutoLock lock(mMutex);
+    listener = mListener;
+  }
+
+  if (listener) {
+    listener->OnThreadCreated();
+  }
+
+  do {
+    nsCOMPtr<nsIRunnable> event;
+    {
+      MutexAutoLock lock(mMutex);
+
+      if (!mEvents.GetPendingEvent(getter_AddRefs(event), lock)) {
+        PRIntervalTime now     = PR_IntervalNow();
+        PRIntervalTime timeout = PR_MillisecondsToInterval(mIdleThreadTimeout);
+
+        // If we are shutting down, then don't keep any idle threads
+        if (mShutdown) {
+          exitThread = true;
+        } else {
+          if (wasIdle) {
+            // if too many idle threads or idle for too long, then bail.
+            if (mIdleCount > mIdleThreadLimit ||
+                (mIdleThreadTimeout != UINT32_MAX && (now - idleSince) >= timeout)) {
+              exitThread = true;
+            }
+          } else {
+            // if would be too many idle threads...
+            if (mIdleCount == mIdleThreadLimit) {
+              exitThread = true;
+            } else {
+              ++mIdleCount;
+              idleSince = now;
+              wasIdle = true;
+            }
+          }
+        }
+
+        if (exitThread) {
+          if (wasIdle) {
+            --mIdleCount;
+          }
+          shutdownThreadOnExit = mThreads.RemoveObject(current);
+        } else {
+          PRIntervalTime delta = timeout - (now - idleSince);
+          LOG(("THRD-P(%p) %s waiting [%d]\n", this, mName.BeginReading(), delta));
+          mEvents.Wait(delta);
+          LOG(("THRD-P(%p) done waiting\n", this));
+        }
+      } else if (wasIdle) {
+        wasIdle = false;
+        --mIdleCount;
+      }
+    }
+    if (event) {
+      LOG(("THRD-P(%p) %s running [%p]\n", this, mName.BeginReading(), event.get()));
+      event->Run();
+    }
+  } while (!exitThread);
+
+  if (listener) {
+    listener->OnThreadShuttingDown();
+  }
+
+  if (shutdownThreadOnExit) {
+    ShutdownThread(current);
+  }
+
+  LOG(("THRD-P(%p) leave\n", this));
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadPool::DispatchFromScript(nsIRunnable* aEvent, uint32_t aFlags)
+{
+  nsCOMPtr<nsIRunnable> event(aEvent);
+  return Dispatch(event.forget(), aFlags);
+}
+
+NS_IMETHODIMP
+nsThreadPool::Dispatch(already_AddRefed<nsIRunnable> aEvent, uint32_t aFlags)
+{
+  LOG(("THRD-P(%p) dispatch [%p %x]\n", this, /* XXX aEvent*/ nullptr, aFlags));
+
+  if (NS_WARN_IF(mShutdown)) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  if (aFlags & DISPATCH_SYNC) {
+    nsCOMPtr<nsIThread> thread;
+    nsThreadManager::get().GetCurrentThread(getter_AddRefs(thread));
+    if (NS_WARN_IF(!thread)) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+
+    RefPtr<nsThreadSyncDispatch> wrapper =
+      new nsThreadSyncDispatch(thread, Move(aEvent));
+    PutEvent(wrapper);
+
+    while (wrapper->IsPending()) {
+      NS_ProcessNextEvent(thread);
+    }
+  } else {
+    NS_ASSERTION(aFlags == NS_DISPATCH_NORMAL ||
+                 aFlags == NS_DISPATCH_AT_END, "unexpected dispatch flags");
+    PutEvent(Move(aEvent), aFlags);
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadPool::DelayedDispatch(already_AddRefed<nsIRunnable>, uint32_t)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsThreadPool::IsOnCurrentThread(bool* aResult)
+{
+  MutexAutoLock lock(mMutex);
+  if (NS_WARN_IF(mShutdown)) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  nsIThread* thread = NS_GetCurrentThread();
+  for (uint32_t i = 0; i < static_cast<uint32_t>(mThreads.Count()); ++i) {
+    if (mThreads[i] == thread) {
+      *aResult = true;
+      return NS_OK;
+    }
+  }
+  *aResult = false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadPool::Shutdown()
+{
+  nsCOMArray<nsIThread> threads;
+  nsCOMPtr<nsIThreadPoolListener> listener;
+  {
+    MutexAutoLock lock(mMutex);
+    mShutdown = true;
+    mEvents.NotifyAll();
+
+    threads.AppendObjects(mThreads);
+    mThreads.Clear();
+
+    // Swap in a null listener so that we release the listener at the end of
+    // this method. The listener will be kept alive as long as the other threads
+    // that were created when it was set.
+    mListener.swap(listener);
+  }
+
+  // It's important that we shutdown the threads while outside the event queue
+  // monitor.  Otherwise, we could end up dead-locking.
+
+  for (int32_t i = 0; i < threads.Count(); ++i) {
+    threads[i]->Shutdown();
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadPool::GetThreadLimit(uint32_t* aValue)
+{
+  *aValue = mThreadLimit;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadPool::SetThreadLimit(uint32_t aValue)
+{
+  MutexAutoLock lock(mMutex);
+  LOG(("THRD-P(%p) thread limit [%u]\n", this, aValue));
+  mThreadLimit = aValue;
+  if (mIdleThreadLimit > mThreadLimit) {
+    mIdleThreadLimit = mThreadLimit;
+  }
+
+  if (static_cast<uint32_t>(mThreads.Count()) > mThreadLimit) {
+    mEvents.NotifyAll();  // wake up threads so they observe this change
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadPool::GetIdleThreadLimit(uint32_t* aValue)
+{
+  *aValue = mIdleThreadLimit;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadPool::SetIdleThreadLimit(uint32_t aValue)
+{
+  MutexAutoLock lock(mMutex);
+  LOG(("THRD-P(%p) idle thread limit [%u]\n", this, aValue));
+  mIdleThreadLimit = aValue;
+  if (mIdleThreadLimit > mThreadLimit) {
+    mIdleThreadLimit = mThreadLimit;
+  }
+
+  // Do we need to kill some idle threads?
+  if (mIdleCount > mIdleThreadLimit) {
+    mEvents.NotifyAll();  // wake up threads so they observe this change
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadPool::GetIdleThreadTimeout(uint32_t* aValue)
+{
+  *aValue = mIdleThreadTimeout;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadPool::SetIdleThreadTimeout(uint32_t aValue)
+{
+  MutexAutoLock lock(mMutex);
+  uint32_t oldTimeout = mIdleThreadTimeout;
+  mIdleThreadTimeout = aValue;
+
+  // Do we need to notify any idle threads that their sleep time has shortened?
+  if (mIdleThreadTimeout < oldTimeout && mIdleCount > 0) {
+    mEvents.NotifyAll();  // wake up threads so they observe this change
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadPool::GetThreadStackSize(uint32_t* aValue)
+{
+  MutexAutoLock lock(mMutex);
+  *aValue = mStackSize;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadPool::SetThreadStackSize(uint32_t aValue)
+{
+  MutexAutoLock lock(mMutex);
+  mStackSize = aValue;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadPool::GetListener(nsIThreadPoolListener** aListener)
+{
+  MutexAutoLock lock(mMutex);
+  NS_IF_ADDREF(*aListener = mListener);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadPool::SetListener(nsIThreadPoolListener* aListener)
+{
+  nsCOMPtr<nsIThreadPoolListener> swappedListener(aListener);
+  {
+    MutexAutoLock lock(mMutex);
+    mListener.swap(swappedListener);
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadPool::SetName(const nsACString& aName)
+{
+  {
+    MutexAutoLock lock(mMutex);
+    if (mThreads.Count()) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+  }
+
+  mName = aName;
+  return NS_OK;
+}
diff --git a/xpcom/threads/nsThreadPool.h b/xpcom/threads/nsThreadPool.h
new file mode 100644
index 000000000..47a4bd1ff
--- /dev/null
+++ b/xpcom/threads/nsThreadPool.h
@@ -0,0 +1,65 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsThreadPool_h__
+#define nsThreadPool_h__
+
+#include "nsIThreadPool.h"
+#include "nsIThread.h"
+#include "nsIRunnable.h"
+#include "nsEventQueue.h"
+#include "nsCOMArray.h"
+#include "nsCOMPtr.h"
+#include "nsThreadUtils.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/AlreadyAddRefed.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/Monitor.h"
+
+class nsThreadPool final
+  : public nsIThreadPool
+  , public nsIRunnable
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIEVENTTARGET
+  NS_DECL_NSITHREADPOOL
+  NS_DECL_NSIRUNNABLE
+  using nsIEventTarget::Dispatch;
+
+  nsThreadPool();
+
+private:
+  ~nsThreadPool();
+
+  void ShutdownThread(nsIThread* aThread);
+  nsresult PutEvent(nsIRunnable* aEvent);
+  nsresult PutEvent(already_AddRefed<nsIRunnable> aEvent, uint32_t aFlags);
+
+  nsCOMArray<nsIThread> mThreads;
+  mozilla::Mutex        mMutex;
+  mozilla::CondVar      mEventsAvailable;
+  nsEventQueue          mEvents;
+  uint32_t              mThreadLimit;
+  uint32_t              mIdleThreadLimit;
+  uint32_t              mIdleThreadTimeout;
+  uint32_t              mIdleCount;
+  uint32_t              mStackSize;
+  nsCOMPtr<nsIThreadPoolListener> mListener;
+  bool                  mShutdown;
+  nsCString             mName;
+  nsThreadPoolNaming    mThreadNaming;
+};
+
+#define NS_THREADPOOL_CID                          \
+{ /* 547ec2a8-315e-4ec4-888e-6e4264fe90eb */       \
+  0x547ec2a8,                                      \
+  0x315e,                                          \
+  0x4ec4,                                          \
+  {0x88, 0x8e, 0x6e, 0x42, 0x64, 0xfe, 0x90, 0xeb} \
+}
+
+#endif  // nsThreadPool_h__
diff --git a/xpcom/threads/nsThreadSyncDispatch.h b/xpcom/threads/nsThreadSyncDispatch.h
new file mode 100644
index 000000000..ae5e85464
--- /dev/null
+++ b/xpcom/threads/nsThreadSyncDispatch.h
@@ -0,0 +1,50 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsThreadSyncDispatch_h_
+#define nsThreadSyncDispatch_h_
+
+#include "nsThreadUtils.h"
+#include "LeakRefPtr.h"
+#include "mozilla/DebugOnly.h"
+
+class nsThreadSyncDispatch : public mozilla::Runnable
+{
+public:
+  nsThreadSyncDispatch(nsIThread* aOrigin, already_AddRefed<nsIRunnable>&& aTask)
+    : mOrigin(aOrigin)
+    , mSyncTask(mozilla::Move(aTask))
+  {
+  }
+
+  bool IsPending()
+  {
+    return !!mSyncTask;
+  }
+
+private:
+  NS_IMETHOD Run() override
+  {
+    if (nsIRunnable* task = mSyncTask.get()) {
+      mozilla::DebugOnly<nsresult> result = task->Run();
+      MOZ_ASSERT(NS_SUCCEEDED(result),
+                 "task in sync dispatch should not fail");
+      // We must release the task here to ensure that when the original
+      // thread is unblocked, this task has been released.
+      mSyncTask.release();
+      // unblock the origin thread
+      mOrigin->Dispatch(this, NS_DISPATCH_NORMAL);
+    }
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIThread> mOrigin;
+  // The task is leaked by default when Run() is not called, because
+  // otherwise we may release it in an incorrect thread.
+  mozilla::LeakRefPtr<nsIRunnable> mSyncTask;
+};
+
+#endif // nsThreadSyncDispatch_h_
diff --git a/xpcom/threads/nsTimerImpl.cpp b/xpcom/threads/nsTimerImpl.cpp
new file mode 100644
index 000000000..bc2d338e0
--- /dev/null
+++ b/xpcom/threads/nsTimerImpl.cpp
@@ -0,0 +1,658 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsTimerImpl.h"
+#include "TimerThread.h"
+#include "nsAutoPtr.h"
+#include "nsThreadManager.h"
+#include "nsThreadUtils.h"
+#include "pratom.h"
+#include "GeckoProfiler.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/IntegerPrintfMacros.h"
+#include "mozilla/Logging.h"
+#ifdef MOZ_TASK_TRACER
+#include "GeckoTaskTracerImpl.h"
+using namespace mozilla::tasktracer;
+#endif
+
+#ifdef XP_WIN
+#include <process.h>
+#ifndef getpid
+#define getpid _getpid
+#endif
+#else
+#include <unistd.h>
+#endif
+
+using mozilla::Atomic;
+using mozilla::LogLevel;
+using mozilla::TimeDuration;
+using mozilla::TimeStamp;
+
+static TimerThread*     gThread = nullptr;
+
+// This module prints info about the precision of timers.
+static mozilla::LazyLogModule sTimerLog("nsTimerImpl");
+
+mozilla::LogModule*
+GetTimerLog()
+{
+  return sTimerLog;
+}
+
+// This module prints info about which timers are firing, which is useful for
+// wakeups for the purposes of power profiling. Set the following environment
+// variable before starting the browser.
+//
+//   MOZ_LOG=TimerFirings:4
+//
+// Then a line will be printed for every timer that fires. The name used for a
+// |Callback::Type::Function| timer depends on the circumstances.
+//
+// - If it was explicitly named (e.g. it was initialized with
+//   InitWithNamedFuncCallback()) then that explicit name will be shown.
+//
+// - Otherwise, if we are on a platform that supports function name lookup
+//   (Mac or Linux) then the looked-up name will be shown with a
+//   "[from dladdr]" annotation. On Mac the looked-up name will be immediately
+//   useful. On Linux it'll need post-processing with
+//   tools/rb/fix_linux_stack.py.
+//
+// - Otherwise, no name will be printed. If many timers hit this case then
+//   you'll need to re-run the workload on a Mac to find out which timers they
+//   are, and then give them explicit names.
+//
+// If you redirect this output to a file called "out", you can then
+// post-process it with a command something like the following.
+//
+//   cat out | grep timer | sort | uniq -c | sort -r -n
+//
+// This will show how often each unique line appears, with the most common ones
+// first.
+//
+// More detailed docs are here:
+// https://developer.mozilla.org/en-US/docs/Mozilla/Performance/TimerFirings_logging
+//
+static mozilla::LazyLogModule sTimerFiringsLog("TimerFirings");
+
+mozilla::LogModule*
+GetTimerFiringsLog()
+{
+  return sTimerFiringsLog;
+}
+
+#include <math.h>
+
+double nsTimerImpl::sDeltaSumSquared = 0;
+double nsTimerImpl::sDeltaSum = 0;
+double nsTimerImpl::sDeltaNum = 0;
+
+static void
+myNS_MeanAndStdDev(double n, double sumOfValues, double sumOfSquaredValues,
+                   double* meanResult, double* stdDevResult)
+{
+  double mean = 0.0, var = 0.0, stdDev = 0.0;
+  if (n > 0.0 && sumOfValues >= 0) {
+    mean = sumOfValues / n;
+    double temp = (n * sumOfSquaredValues) - (sumOfValues * sumOfValues);
+    if (temp < 0.0 || n <= 1) {
+      var = 0.0;
+    } else {
+      var = temp / (n * (n - 1));
+    }
+    // for some reason, Windows says sqrt(0.0) is "-1.#J" (?!) so do this:
+    stdDev = var != 0.0 ? sqrt(var) : 0.0;
+  }
+  *meanResult = mean;
+  *stdDevResult = stdDev;
+}
+
+NS_IMPL_QUERY_INTERFACE(nsTimer, nsITimer)
+NS_IMPL_ADDREF(nsTimer)
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsTimer::Release(void)
+{
+  nsrefcnt count = --mRefCnt;
+  NS_LOG_RELEASE(this, count, "nsTimer");
+
+  if (count == 1) {
+    // Last ref, held by nsTimerImpl. Make sure the cycle is broken.
+    // If there is a nsTimerEvent in a queue for this timer, the nsTimer will
+    // live until that event pops, otherwise the nsTimerImpl will go away and
+    // the nsTimer along with it.
+    mImpl->Cancel();
+    mImpl = nullptr;
+  } else if (count == 0) {
+    delete this;
+  }
+
+  return count;
+}
+
+nsTimerImpl::nsTimerImpl(nsITimer* aTimer) :
+  mGeneration(0),
+  mDelay(0),
+  mITimer(aTimer),
+  mMutex("nsTimerImpl::mMutex")
+{
+  // XXXbsmedberg: shouldn't this be in Init()?
+  mEventTarget = static_cast<nsIEventTarget*>(NS_GetCurrentThread());
+}
+
+//static
+nsresult
+nsTimerImpl::Startup()
+{
+  nsresult rv;
+
+  gThread = new TimerThread();
+
+  NS_ADDREF(gThread);
+  rv = gThread->InitLocks();
+
+  if (NS_FAILED(rv)) {
+    NS_RELEASE(gThread);
+  }
+
+  return rv;
+}
+
+void
+nsTimerImpl::Shutdown()
+{
+  if (MOZ_LOG_TEST(GetTimerLog(), LogLevel::Debug)) {
+    double mean = 0, stddev = 0;
+    myNS_MeanAndStdDev(sDeltaNum, sDeltaSum, sDeltaSumSquared, &mean, &stddev);
+
+    MOZ_LOG(GetTimerLog(), LogLevel::Debug,
+           ("sDeltaNum = %f, sDeltaSum = %f, sDeltaSumSquared = %f\n",
+            sDeltaNum, sDeltaSum, sDeltaSumSquared));
+    MOZ_LOG(GetTimerLog(), LogLevel::Debug,
+           ("mean: %fms, stddev: %fms\n", mean, stddev));
+  }
+
+  if (!gThread) {
+    return;
+  }
+
+  gThread->Shutdown();
+  NS_RELEASE(gThread);
+}
+
+
+nsresult
+nsTimerImpl::InitCommon(uint32_t aDelay, uint32_t aType)
+{
+  mMutex.AssertCurrentThreadOwns();
+  nsresult rv;
+
+  if (NS_WARN_IF(!gThread)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  if (!mEventTarget) {
+    NS_ERROR("mEventTarget is NULL");
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  rv = gThread->Init();
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  gThread->RemoveTimer(this);
+  ++mGeneration;
+
+  mType = (uint8_t)aType;
+  mDelay = aDelay;
+  mTimeout = TimeStamp::Now() + TimeDuration::FromMilliseconds(mDelay);
+
+  return gThread->AddTimer(this);
+}
+
+nsresult
+nsTimerImpl::InitWithFuncCallbackCommon(nsTimerCallbackFunc aFunc,
+                                        void* aClosure,
+                                        uint32_t aDelay,
+                                        uint32_t aType,
+                                        Callback::Name aName)
+{
+  if (NS_WARN_IF(!aFunc)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  Callback cb; // Goes out of scope after the unlock, prevents deadlock
+  cb.mType = Callback::Type::Function;
+  cb.mCallback.c = aFunc;
+  cb.mClosure = aClosure;
+  cb.mName = aName;
+
+  MutexAutoLock lock(mMutex);
+  cb.swap(mCallback);
+
+  return InitCommon(aDelay, aType);
+}
+
+NS_IMETHODIMP
+nsTimerImpl::InitWithFuncCallback(nsTimerCallbackFunc aFunc,
+                                  void* aClosure,
+                                  uint32_t aDelay,
+                                  uint32_t aType)
+{
+  Callback::Name name(Callback::Nothing);
+  return InitWithFuncCallbackCommon(aFunc, aClosure, aDelay, aType, name);
+}
+
+NS_IMETHODIMP
+nsTimerImpl::InitWithNamedFuncCallback(nsTimerCallbackFunc aFunc,
+                                       void* aClosure,
+                                       uint32_t aDelay,
+                                       uint32_t aType,
+                                       const char* aNameString)
+{
+  Callback::Name name(aNameString);
+  return InitWithFuncCallbackCommon(aFunc, aClosure, aDelay, aType, name);
+}
+
+NS_IMETHODIMP
+nsTimerImpl::InitWithNameableFuncCallback(nsTimerCallbackFunc aFunc,
+                                          void* aClosure,
+                                          uint32_t aDelay,
+                                          uint32_t aType,
+                                          nsTimerNameCallbackFunc aNameFunc)
+{
+  Callback::Name name(aNameFunc);
+  return InitWithFuncCallbackCommon(aFunc, aClosure, aDelay, aType, name);
+}
+
+NS_IMETHODIMP
+nsTimerImpl::InitWithCallback(nsITimerCallback* aCallback,
+                              uint32_t aDelay,
+                              uint32_t aType)
+{
+  if (NS_WARN_IF(!aCallback)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  Callback cb; // Goes out of scope after the unlock, prevents deadlock
+  cb.mType = Callback::Type::Interface;
+  cb.mCallback.i = aCallback;
+  NS_ADDREF(cb.mCallback.i);
+
+  MutexAutoLock lock(mMutex);
+  cb.swap(mCallback);
+
+  return InitCommon(aDelay, aType);
+}
+
+NS_IMETHODIMP
+nsTimerImpl::Init(nsIObserver* aObserver, uint32_t aDelay, uint32_t aType)
+{
+  if (NS_WARN_IF(!aObserver)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  Callback cb; // Goes out of scope after the unlock, prevents deadlock
+  cb.mType = Callback::Type::Observer;
+  cb.mCallback.o = aObserver;
+  NS_ADDREF(cb.mCallback.o);
+
+  MutexAutoLock lock(mMutex);
+  cb.swap(mCallback);
+
+  return InitCommon(aDelay, aType);
+}
+
+NS_IMETHODIMP
+nsTimerImpl::Cancel()
+{
+  Callback cb;
+
+  MutexAutoLock lock(mMutex);
+
+  if (gThread) {
+    gThread->RemoveTimer(this);
+  }
+
+  cb.swap(mCallback);
+  ++mGeneration;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTimerImpl::SetDelay(uint32_t aDelay)
+{
+  MutexAutoLock lock(mMutex);
+  if (GetCallback().mType == Callback::Type::Unknown && !IsRepeating()) {
+    // This may happen if someone tries to re-use a one-shot timer
+    // by re-setting delay instead of reinitializing the timer.
+    NS_ERROR("nsITimer->SetDelay() called when the "
+             "one-shot timer is not set up.");
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  bool reAdd = false;
+  if (gThread) {
+    reAdd = NS_SUCCEEDED(gThread->RemoveTimer(this));
+  }
+
+  mDelay = aDelay;
+  mTimeout = TimeStamp::Now() + TimeDuration::FromMilliseconds(mDelay);
+
+  if (reAdd) {
+    gThread->AddTimer(this);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTimerImpl::GetDelay(uint32_t* aDelay)
+{
+  MutexAutoLock lock(mMutex);
+  *aDelay = mDelay;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTimerImpl::SetType(uint32_t aType)
+{
+  MutexAutoLock lock(mMutex);
+  mType = (uint8_t)aType;
+  // XXX if this is called, we should change the actual type.. this could effect
+  // repeating timers.  we need to ensure in Fire() that if mType has changed
+  // during the callback that we don't end up with the timer in the queue twice.
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTimerImpl::GetType(uint32_t* aType)
+{
+  MutexAutoLock lock(mMutex);
+  *aType = mType;
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsTimerImpl::GetClosure(void** aClosure)
+{
+  MutexAutoLock lock(mMutex);
+  *aClosure = GetCallback().mClosure;
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsTimerImpl::GetCallback(nsITimerCallback** aCallback)
+{
+  MutexAutoLock lock(mMutex);
+  if (GetCallback().mType == Callback::Type::Interface) {
+    NS_IF_ADDREF(*aCallback = GetCallback().mCallback.i);
+  } else {
+    *aCallback = nullptr;
+  }
+
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsTimerImpl::GetTarget(nsIEventTarget** aTarget)
+{
+  MutexAutoLock lock(mMutex);
+  NS_IF_ADDREF(*aTarget = mEventTarget);
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsTimerImpl::SetTarget(nsIEventTarget* aTarget)
+{
+  MutexAutoLock lock(mMutex);
+  if (NS_WARN_IF(mCallback.mType != Callback::Type::Unknown)) {
+    return NS_ERROR_ALREADY_INITIALIZED;
+  }
+
+  if (aTarget) {
+    mEventTarget = aTarget;
+  } else {
+    mEventTarget = static_cast<nsIEventTarget*>(NS_GetCurrentThread());
+  }
+  return NS_OK;
+}
+
+
+void
+nsTimerImpl::Fire(int32_t aGeneration)
+{
+  uint8_t oldType;
+  uint32_t oldDelay;
+  TimeStamp oldTimeout;
+
+  {
+    // Don't fire callbacks or fiddle with refcounts when the mutex is locked.
+    // If some other thread Cancels/Inits after this, they're just too late.
+    MutexAutoLock lock(mMutex);
+    if (aGeneration != mGeneration) {
+      return;
+    }
+
+    mCallbackDuringFire.swap(mCallback);
+    oldType = mType;
+    oldDelay = mDelay;
+    oldTimeout = mTimeout;
+  }
+
+  PROFILER_LABEL("Timer", "Fire",
+                 js::ProfileEntry::Category::OTHER);
+
+  TimeStamp now = TimeStamp::Now();
+  if (MOZ_LOG_TEST(GetTimerLog(), LogLevel::Debug)) {
+    TimeDuration   delta = now - oldTimeout;
+    int32_t       d = delta.ToMilliseconds(); // delta in ms
+    sDeltaSum += abs(d);
+    sDeltaSumSquared += double(d) * double(d);
+    sDeltaNum++;
+
+    MOZ_LOG(GetTimerLog(), LogLevel::Debug,
+           ("[this=%p] expected delay time %4ums\n", this, oldDelay));
+    MOZ_LOG(GetTimerLog(), LogLevel::Debug,
+           ("[this=%p] actual delay time   %4dms\n", this, oldDelay + d));
+    MOZ_LOG(GetTimerLog(), LogLevel::Debug,
+           ("[this=%p] (mType is %d)       -------\n", this, oldType));
+    MOZ_LOG(GetTimerLog(), LogLevel::Debug,
+           ("[this=%p]     delta           %4dms\n", this, d));
+  }
+
+  if (MOZ_LOG_TEST(GetTimerFiringsLog(), LogLevel::Debug)) {
+    LogFiring(mCallbackDuringFire, oldType, oldDelay);
+  }
+
+  switch (mCallbackDuringFire.mType) {
+    case Callback::Type::Function:
+      mCallbackDuringFire.mCallback.c(mITimer, mCallbackDuringFire.mClosure);
+      break;
+    case Callback::Type::Interface:
+      mCallbackDuringFire.mCallback.i->Notify(mITimer);
+      break;
+    case Callback::Type::Observer:
+      mCallbackDuringFire.mCallback.o->Observe(mITimer, NS_TIMER_CALLBACK_TOPIC,
+                                               nullptr);
+      break;
+    default:
+      ;
+  }
+
+  Callback trash; // Swap into here to dispose of callback after the unlock
+  MutexAutoLock lock(mMutex);
+  if (aGeneration == mGeneration && IsRepeating()) {
+    // Repeating timer has not been re-init or canceled; reschedule
+    mCallbackDuringFire.swap(mCallback);
+    TimeDuration delay = TimeDuration::FromMilliseconds(mDelay);
+    if (mType == nsITimer::TYPE_REPEATING_SLACK) {
+      mTimeout = TimeStamp::Now() + delay;
+    } else {
+      mTimeout = mTimeout + delay;
+    }
+    if (gThread) {
+      gThread->AddTimer(this);
+    }
+  }
+
+  mCallbackDuringFire.swap(trash);
+
+  MOZ_LOG(GetTimerLog(), LogLevel::Debug,
+         ("[this=%p] Took %fms to fire timer callback\n",
+          this, (TimeStamp::Now() - now).ToMilliseconds()));
+}
+
+#if defined(HAVE_DLADDR) && defined(HAVE___CXA_DEMANGLE)
+#define USE_DLADDR 1
+#endif
+
+#ifdef USE_DLADDR
+#include <cxxabi.h>
+#include <dlfcn.h>
+#endif
+
+// See the big comment above GetTimerFiringsLog() to understand this code.
+void
+nsTimerImpl::LogFiring(const Callback& aCallback, uint8_t aType, uint32_t aDelay)
+{
+  const char* typeStr;
+  switch (aType) {
+    case nsITimer::TYPE_ONE_SHOT:                   typeStr = "ONE_SHOT"; break;
+    case nsITimer::TYPE_REPEATING_SLACK:            typeStr = "SLACK   "; break;
+    case nsITimer::TYPE_REPEATING_PRECISE:          /* fall through */
+    case nsITimer::TYPE_REPEATING_PRECISE_CAN_SKIP: typeStr = "PRECISE "; break;
+    default:                              MOZ_CRASH("bad type");
+  }
+
+  switch (aCallback.mType) {
+    case Callback::Type::Function: {
+      bool needToFreeName = false;
+      const char* annotation = "";
+      const char* name;
+      static const size_t buflen = 1024;
+      char buf[buflen];
+
+      if (aCallback.mName.is<Callback::NameString>()) {
+        name = aCallback.mName.as<Callback::NameString>();
+
+      } else if (aCallback.mName.is<Callback::NameFunc>()) {
+        aCallback.mName.as<Callback::NameFunc>()(
+            mITimer, aCallback.mClosure, buf, buflen);
+        name = buf;
+
+      } else {
+        MOZ_ASSERT(aCallback.mName.is<Callback::NameNothing>());
+#ifdef USE_DLADDR
+        annotation = "[from dladdr] ";
+
+        Dl_info info;
+        void* addr = reinterpret_cast<void*>(aCallback.mCallback.c);
+        if (dladdr(addr, &info) == 0) {
+          name = "???[dladdr: failed]";
+
+        } else if (info.dli_sname) {
+          int status;
+          name = abi::__cxa_demangle(info.dli_sname, nullptr, nullptr, &status);
+          if (status == 0) {
+            // Success. Because we didn't pass in a buffer to __cxa_demangle it
+            // allocates its own one with malloc() which we must free() later.
+            MOZ_ASSERT(name);
+            needToFreeName = true;
+          } else if (status == -1) {
+            name = "???[__cxa_demangle: OOM]";
+          } else if (status == -2) {
+            name = "???[__cxa_demangle: invalid mangled name]";
+          } else if (status == -3) {
+            name = "???[__cxa_demangle: invalid argument]";
+          } else {
+            name = "???[__cxa_demangle: unexpected status value]";
+          }
+
+        } else if (info.dli_fname) {
+          // The "#0: " prefix is necessary for fix_linux_stack.py to interpret
+          // this string as something to convert.
+          snprintf(buf, buflen, "#0: ???[%s +0x%" PRIxPTR "]\n",
+                   info.dli_fname, uintptr_t(addr) - uintptr_t(info.dli_fbase));
+          name = buf;
+
+        } else {
+          name = "???[dladdr: no symbol or shared object obtained]";
+        }
+#else
+        name = "???[dladdr is unimplemented or doesn't work well on this OS]";
+#endif
+      }
+
+      MOZ_LOG(GetTimerFiringsLog(), LogLevel::Debug,
+              ("[%d]    fn timer (%s %5d ms): %s%s\n",
+               getpid(), typeStr, aDelay, annotation, name));
+
+      if (needToFreeName) {
+        free(const_cast<char*>(name));
+      }
+
+      break;
+    }
+
+    case Callback::Type::Interface: {
+      MOZ_LOG(GetTimerFiringsLog(), LogLevel::Debug,
+              ("[%d] iface timer (%s %5d ms): %p\n",
+               getpid(), typeStr, aDelay, aCallback.mCallback.i));
+      break;
+    }
+
+    case Callback::Type::Observer: {
+      MOZ_LOG(GetTimerFiringsLog(), LogLevel::Debug,
+              ("[%d]   obs timer (%s %5d ms): %p\n",
+               getpid(), typeStr, aDelay, aCallback.mCallback.o));
+      break;
+    }
+
+    case Callback::Type::Unknown:
+    default: {
+      MOZ_LOG(GetTimerFiringsLog(), LogLevel::Debug,
+              ("[%d]   ??? timer (%s, %5d ms)\n",
+               getpid(), typeStr, aDelay));
+      break;
+    }
+  }
+}
+
+nsTimer::~nsTimer()
+{
+}
+
+size_t
+nsTimer::SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+{
+  return aMallocSizeOf(this);
+}
+
+/* static */
+const nsTimerImpl::Callback::NameNothing nsTimerImpl::Callback::Nothing = 0;
+
+#ifdef MOZ_TASK_TRACER
+void
+nsTimerImpl::GetTLSTraceInfo()
+{
+  mTracedTask.GetTLSTraceInfo();
+}
+
+TracedTaskCommon
+nsTimerImpl::GetTracedTask()
+{
+  return mTracedTask;
+}
+
+#endif
+
diff --git a/xpcom/threads/nsTimerImpl.h b/xpcom/threads/nsTimerImpl.h
new file mode 100644
index 000000000..5c731fbb4
--- /dev/null
+++ b/xpcom/threads/nsTimerImpl.h
@@ -0,0 +1,207 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTimerImpl_h___
+#define nsTimerImpl_h___
+
+#include "nsITimer.h"
+#include "nsIEventTarget.h"
+#include "nsIObserver.h"
+
+#include "nsCOMPtr.h"
+
+#include "mozilla/Attributes.h"
+#include "mozilla/Logging.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/Variant.h"
+
+#ifdef MOZ_TASK_TRACER
+#include "TracedTaskCommon.h"
+#endif
+
+extern mozilla::LogModule* GetTimerLog();
+
+#define NS_TIMER_CID \
+{ /* 5ff24248-1dd2-11b2-8427-fbab44f29bc8 */         \
+     0x5ff24248,                                     \
+     0x1dd2,                                         \
+     0x11b2,                                         \
+    {0x84, 0x27, 0xfb, 0xab, 0x44, 0xf2, 0x9b, 0xc8} \
+}
+
+// TimerThread, nsTimerEvent, and nsTimer have references to these. nsTimer has
+// a separate lifecycle so we can Cancel() the underlying timer when the user of
+// the nsTimer has let go of its last reference.
+class nsTimerImpl
+{
+  ~nsTimerImpl() {}
+public:
+  typedef mozilla::TimeStamp TimeStamp;
+
+  explicit nsTimerImpl(nsITimer* aTimer);
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(nsTimerImpl)
+  NS_DECL_NON_VIRTUAL_NSITIMER
+
+  static nsresult Startup();
+  static void Shutdown();
+
+  void Fire(int32_t aGeneration);
+
+#ifdef MOZ_TASK_TRACER
+  void GetTLSTraceInfo();
+  mozilla::tasktracer::TracedTaskCommon GetTracedTask();
+#endif
+
+  int32_t GetGeneration()
+  {
+    return mGeneration;
+  }
+
+  nsresult InitCommon(uint32_t aDelay, uint32_t aType);
+
+  struct Callback {
+    Callback() :
+      mType(Type::Unknown),
+      mName(Nothing),
+      mClosure(nullptr)
+    {
+      mCallback.c = nullptr;
+    }
+
+    Callback(const Callback& other) = delete;
+    Callback& operator=(const Callback& other) = delete;
+
+    ~Callback()
+    {
+      if (mType == Type::Interface) {
+        NS_RELEASE(mCallback.i);
+      } else if (mType == Type::Observer) {
+        NS_RELEASE(mCallback.o);
+      }
+    }
+
+    void swap(Callback& other)
+    {
+      std::swap(mType, other.mType);
+      std::swap(mCallback, other.mCallback);
+      std::swap(mName, other.mName);
+      std::swap(mClosure, other.mClosure);
+    }
+
+    enum class Type : uint8_t {
+      Unknown = 0,
+      Interface = 1,
+      Function = 2,
+      Observer = 3,
+    };
+    Type mType;
+
+    union CallbackUnion
+    {
+      nsTimerCallbackFunc c;
+      // These refcounted references are managed manually, as they are in a union
+      nsITimerCallback* MOZ_OWNING_REF i;
+      nsIObserver* MOZ_OWNING_REF o;
+    } mCallback;
+
+    // |Name| is a tagged union type representing one of (a) nothing, (b) a
+    // string, or (c) a function. mozilla::Variant doesn't naturally handle the
+    // "nothing" case, so we define a dummy type and value (which is unused and
+    // so the exact value doesn't matter) for it.
+    typedef const int NameNothing;
+    typedef const char* NameString;
+    typedef nsTimerNameCallbackFunc NameFunc;
+    typedef mozilla::Variant<NameNothing, NameString, NameFunc> Name;
+    static const NameNothing Nothing;
+    Name mName;
+
+    void*                 mClosure;
+  };
+
+  Callback& GetCallback()
+  {
+    mMutex.AssertCurrentThreadOwns();
+    if (mCallback.mType == Callback::Type::Unknown) {
+      return mCallbackDuringFire;
+    }
+
+    return mCallback;
+  }
+
+  bool IsRepeating() const
+  {
+    static_assert(nsITimer::TYPE_ONE_SHOT < nsITimer::TYPE_REPEATING_SLACK,
+                  "invalid ordering of timer types!");
+    static_assert(
+        nsITimer::TYPE_REPEATING_SLACK < nsITimer::TYPE_REPEATING_PRECISE,
+        "invalid ordering of timer types!");
+    static_assert(
+        nsITimer::TYPE_REPEATING_PRECISE <
+          nsITimer::TYPE_REPEATING_PRECISE_CAN_SKIP,
+        "invalid ordering of timer types!");
+    return mType >= nsITimer::TYPE_REPEATING_SLACK;
+  }
+
+  nsCOMPtr<nsIEventTarget> mEventTarget;
+
+  void LogFiring(const Callback& aCallback, uint8_t aType, uint32_t aDelay);
+
+  nsresult InitWithFuncCallbackCommon(nsTimerCallbackFunc aFunc,
+                                      void* aClosure,
+                                      uint32_t aDelay,
+                                      uint32_t aType,
+                                      Callback::Name aName);
+
+  // These members are set by the initiating thread, when the timer's type is
+  // changed and during the period where it fires on that thread.
+  uint8_t               mType;
+
+  // The generation number of this timer, re-generated each time the timer is
+  // initialized so one-shot timers can be canceled and re-initialized by the
+  // arming thread without any bad race conditions.
+  // Updated only after this timer has been removed from the timer thread.
+  int32_t               mGeneration;
+
+  uint32_t              mDelay;
+  // Updated only after this timer has been removed from the timer thread.
+  TimeStamp             mTimeout;
+
+#ifdef MOZ_TASK_TRACER
+  mozilla::tasktracer::TracedTaskCommon mTracedTask;
+#endif
+
+  static double         sDeltaSum;
+  static double         sDeltaSumSquared;
+  static double         sDeltaNum;
+  const RefPtr<nsITimer>      mITimer;
+  mozilla::Mutex mMutex;
+  Callback              mCallback;
+  Callback              mCallbackDuringFire;
+};
+
+class nsTimer final : public nsITimer
+{
+  virtual ~nsTimer();
+public:
+  nsTimer() : mImpl(new nsTimerImpl(this)) {}
+
+  friend class TimerThread;
+  friend class nsTimerEvent;
+  friend struct TimerAdditionComparator;
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_FORWARD_SAFE_NSITIMER(mImpl);
+
+  virtual size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const override;
+
+private:
+  // nsTimerImpl holds a strong ref to us. When our refcount goes to 1, we will
+  // null this to break the cycle.
+  RefPtr<nsTimerImpl> mImpl;
+};
+
+#endif /* nsTimerImpl_h___ */
diff --git a/xpcom/typelib/moz.build b/xpcom/typelib/moz.build
new file mode 100644
index 000000000..3d82a998d
--- /dev/null
+++ b/xpcom/typelib/moz.build
@@ -0,0 +1,8 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += ['xpt']
+
diff --git a/xpcom/typelib/xpt/moz.build b/xpcom/typelib/xpt/moz.build
new file mode 100644
index 000000000..80b9160b0
--- /dev/null
+++ b/xpcom/typelib/xpt/moz.build
@@ -0,0 +1,40 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+Library('xpt')
+
+DIRS += ['tools']
+
+UNIFIED_SOURCES += [
+    'xpt_arena.cpp',
+    'xpt_struct.cpp',
+    'xpt_xdr.cpp',
+]
+
+EXPORTS += [
+    'xpt_arena.h',
+    'xpt_struct.h',
+    'xpt_xdr.h',
+]
+
+FINAL_LIBRARY = 'xul'
+
+LOCAL_INCLUDES += [
+    '!/xpcom/base',
+    '/xpcom/base',
+]
+
+if CONFIG['_MSC_VER']:
+    CFLAGS += ['-Zl']
+
+# Code with FINAL_LIBRARY = 'xul' shouldn't do this, but the code
+# here doesn't use malloc functions anyways, while not setting
+# MOZ_NO_MOZALLOC makes the code include mozalloc.h, which includes
+# inline operator new definitions that MSVC linker doesn't strip
+# when linking the xpt tests.
+DEFINES['MOZ_NO_MOZALLOC'] = True
+
+DIST_INSTALL = True
diff --git a/xpcom/typelib/xpt/tools/moz.build b/xpcom/typelib/xpt/tools/moz.build
new file mode 100644
index 000000000..bd4a2836b
--- /dev/null
+++ b/xpcom/typelib/xpt/tools/moz.build
@@ -0,0 +1,13 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+PYTHON_UNIT_TESTS += [
+    'runtests.py',
+]
+
+SDK_FILES.bin += [
+    'xpt.py',
+]
diff --git a/xpcom/typelib/xpt/tools/runtests.py b/xpcom/typelib/xpt/tools/runtests.py
new file mode 100644
index 000000000..a86e6625d
--- /dev/null
+++ b/xpcom/typelib/xpt/tools/runtests.py
@@ -0,0 +1,770 @@
+#!/usr/bin/env python
+# Copyright 2010,2011 Mozilla Foundation. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#   1. Redistributions of source code must retain the above copyright
+#      notice, this list of conditions and the following disclaimer.
+#
+#   2. Redistributions in binary form must reproduce the above copyright
+#      notice, this list of conditions and the following disclaimer in
+#      the documentation and/or other materials provided with the
+#      distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE MOZILLA FOUNDATION ``AS IS'' AND ANY
+# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE MOZILLA FOUNDATION OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+# OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# The views and conclusions contained in the software and documentation
+# are those of the authors and should not be interpreted as representing
+# official policies, either expressed or implied, of the Mozilla
+# Foundation.
+
+import difflib
+import os
+from StringIO import StringIO
+import subprocess
+import tempfile
+import mozunit
+import unittest
+import xpt
+
+
+def get_output(bin, file):
+    p = subprocess.Popen([bin, file], stdout=subprocess.PIPE)
+    stdout, _ = p.communicate()
+    return stdout
+
+if "MOZILLA_OBJDIR" in os.environ:
+    class CheckXPTDump(unittest.TestCase):
+        def test_xpt_dump_diffs(self):
+            MOZILLA_OBJDIR = os.environ["MOZILLA_OBJDIR"]
+            xptdump = os.path.abspath(os.path.join(MOZILLA_OBJDIR,
+                                                   "dist", "bin", "xpt_dump"))
+            components = os.path.abspath(os.path.join(MOZILLA_OBJDIR,
+                                                      "dist", "bin", "components"))
+            for f in os.listdir(components):
+                if not f.endswith(".xpt"):
+                    continue
+                fullpath = os.path.join(components, f)
+                # read a Typelib and dump it to a string
+                t = xpt.Typelib.read(fullpath)
+                self.assert_(t is not None)
+                outf = StringIO()
+                t.dump(outf)
+                out = outf.getvalue()
+                # now run xpt_dump on it
+                out2 = get_output(xptdump, fullpath)
+                if out != out2:
+                    print "diff %s" % f
+                    for line in difflib.unified_diff(out2.split("\n"), out.split("\n"), lineterm=""):
+                        print line
+                self.assert_(out == out2, "xpt_dump output should be identical for %s" % f)
+
+
+class TestIIDString(unittest.TestCase):
+    def test_iid_str_roundtrip(self):
+        iid_str = "11223344-5566-7788-9900-aabbccddeeff"
+        iid = xpt.Typelib.string_to_iid(iid_str)
+        self.assertEqual(iid_str, xpt.Typelib.iid_to_string(iid))
+
+    def test_iid_roundtrip(self):
+        iid = "\x11\x22\x33\x44\x55\x66\x77\x88\x99\x00\xaa\xbb\xcc\xdd\xee\xff"
+        iid_str = xpt.Typelib.iid_to_string(iid)
+        self.assertEqual(iid, xpt.Typelib.string_to_iid(iid_str))
+
+
+class TypelibCompareMixin:
+    def assertEqualTypelibs(self, t1, t2):
+        self.assert_(t1 is not None, "Should not be None")
+        self.assert_(t2 is not None, "Should not be None")
+        self.assertEqual(t1.version, t2.version, "Versions should be equal")
+        self.assertEqual(len(t1.interfaces), len(t2.interfaces),
+                         "Number of interfaces should be equal")
+        for i, j in zip(t1.interfaces, t2.interfaces):
+            self.assertEqualInterfaces(i, j)
+
+    def assertEqualInterfaces(self, i1, i2):
+        self.assert_(i1 is not None, "Should not be None")
+        self.assert_(i2 is not None, "Should not be None")
+        self.assertEqual(i1.name, i2.name, "Names should be equal")
+        self.assertEqual(i1.iid, i2.iid, "IIDs should be equal")
+        self.assertEqual(i1.namespace, i2.namespace,
+                         "Namespaces should be equal")
+        self.assertEqual(i1.resolved, i2.resolved,
+                         "Resolved status should be equal")
+        if i1.resolved:
+            if i1.parent or i2.parent:
+                # Can't test exact equality, probably different objects
+                self.assertEqualInterfaces(i1.parent, i2.parent)
+            self.assertEqual(len(i1.methods), len(i2.methods))
+            for m, n in zip(i1.methods, i2.methods):
+                self.assertEqualMethods(m, n)
+            self.assertEqual(len(i1.constants), len(i2.constants))
+            for c, d in zip(i1.constants, i2.constants):
+                self.assertEqualConstants(c, d)
+            self.assertEqual(i1.scriptable, i2.scriptable,
+                             "Scriptable status should be equal")
+            self.assertEqual(i1.function, i2.function,
+                             "Function status should be equal")
+
+    def assertEqualMethods(self, m1, m2):
+        self.assert_(m1 is not None, "Should not be None")
+        self.assert_(m2 is not None, "Should not be None")
+        self.assertEqual(m1.name, m2.name, "Names should be equal")
+        self.assertEqual(m1.getter, m2.getter, "Getter flag should be equal")
+        self.assertEqual(m1.setter, m2.setter, "Setter flag should be equal")
+        self.assertEqual(m1.notxpcom, m2.notxpcom,
+                         "notxpcom flag should be equal")
+        self.assertEqual(m1.constructor, m2.constructor,
+                         "constructor flag should be equal")
+        self.assertEqual(m1.hidden, m2.hidden, "hidden flag should be equal")
+        self.assertEqual(m1.optargc, m2.optargc, "optargc flag should be equal")
+        self.assertEqual(m1.implicit_jscontext, m2.implicit_jscontext,
+                         "implicit_jscontext flag should be equal")
+        for p1, p2 in zip(m1.params, m2.params):
+            self.assertEqualParams(p1, p2)
+        self.assertEqualParams(m1.result, m2.result)
+
+    def assertEqualConstants(self, c1, c2):
+        self.assert_(c1 is not None, "Should not be None")
+        self.assert_(c2 is not None, "Should not be None")
+        self.assertEqual(c1.name, c2.name)
+        self.assertEqual(c1.value, c2.value)
+        self.assertEqualTypes(c1.type, c2.type)
+
+    def assertEqualParams(self, p1, p2):
+        self.assert_(p1 is not None, "Should not be None")
+        self.assert_(p2 is not None, "Should not be None")
+        self.assertEqualTypes(p1.type, p2.type)
+        self.assertEqual(p1.in_, p2.in_)
+        self.assertEqual(p1.out, p2.out)
+        self.assertEqual(p1.retval, p2.retval)
+        self.assertEqual(p1.shared, p2.shared)
+        self.assertEqual(p1.dipper, p2.dipper)
+        self.assertEqual(p1.optional, p2.optional)
+
+    def assertEqualTypes(self, t1, t2):
+        self.assert_(t1 is not None, "Should not be None")
+        self.assert_(t2 is not None, "Should not be None")
+        self.assertEqual(type(t1), type(t2), "type types should be equal")
+        self.assertEqual(t1.pointer, t2.pointer,
+                         "pointer flag should be equal for %s and %s" % (t1, t2))
+        self.assertEqual(t1.reference, t2.reference)
+        if isinstance(t1, xpt.SimpleType):
+            self.assertEqual(t1.tag, t2.tag)
+        elif isinstance(t1, xpt.InterfaceType):
+            self.assertEqualInterfaces(t1.iface, t2.iface)
+        elif isinstance(t1, xpt.InterfaceIsType):
+            self.assertEqual(t1.param_index, t2.param_index)
+        elif isinstance(t1, xpt.ArrayType):
+            self.assertEqualTypes(t1.element_type, t2.element_type)
+            self.assertEqual(t1.size_is_arg_num, t2.size_is_arg_num)
+            self.assertEqual(t1.length_is_arg_num, t2.length_is_arg_num)
+        elif isinstance(t1, xpt.StringWithSizeType) or isinstance(t1, xpt.WideStringWithSizeType):
+            self.assertEqual(t1.size_is_arg_num, t2.size_is_arg_num)
+            self.assertEqual(t1.length_is_arg_num, t2.length_is_arg_num)
+
+
+class TestTypelibReadWrite(unittest.TestCase, TypelibCompareMixin):
+    def test_read_file(self):
+        """
+        Test that a Typelib can be read/written from/to a file.
+        """
+        t = xpt.Typelib()
+        # add an unresolved interface
+        t.interfaces.append(xpt.Interface("IFoo"))
+        fd, f = tempfile.mkstemp()
+        os.close(fd)
+        t.write(f)
+        t2 = xpt.Typelib.read(f)
+        os.remove(f)
+        self.assert_(t2 is not None)
+        self.assertEqualTypelibs(t, t2)
+
+
+# TODO: test flags in various combinations
+class TestTypelibRoundtrip(unittest.TestCase, TypelibCompareMixin):
+    def checkRoundtrip(self, t):
+        s = StringIO()
+        t.write(s)
+        s.seek(0)
+        t2 = xpt.Typelib.read(s)
+        self.assert_(t2 is not None)
+        self.assertEqualTypelibs(t, t2)
+
+    def test_simple(self):
+        t = xpt.Typelib()
+        # add an unresolved interface
+        t.interfaces.append(xpt.Interface("IFoo"))
+        self.checkRoundtrip(t)
+
+        t = xpt.Typelib()
+        # add an unresolved interface with an IID
+        t.interfaces.append(xpt.Interface("IBar", "11223344-5566-7788-9900-aabbccddeeff"))
+        self.checkRoundtrip(t)
+
+    def test_parent(self):
+        """
+        Test that an interface's parent property is correctly serialized
+        and deserialized.
+
+        """
+        t = xpt.Typelib()
+        pi = xpt.Interface("IParent")
+        t.interfaces.append(pi)
+        t.interfaces.append(xpt.Interface("IChild", iid="11223344-5566-7788-9900-aabbccddeeff",
+                                          parent=pi, resolved=True))
+        self.checkRoundtrip(t)
+
+    def test_ifaceFlags(self):
+        """
+        Test that an interface's flags are correctly serialized
+        and deserialized.
+
+        """
+        t = xpt.Typelib()
+        t.interfaces.append(xpt.Interface("IFlags", iid="11223344-5566-7788-9900-aabbccddeeff",
+                                          resolved=True,
+                                          scriptable=True,
+                                          function=True))
+        self.checkRoundtrip(t)
+
+    def test_constants(self):
+        c = xpt.Constant("X", xpt.SimpleType(xpt.Type.Tags.uint32),
+                         0xF000F000)
+        i = xpt.Interface("IFoo", iid="11223344-5566-7788-9900-aabbccddeeff",
+                          constants=[c])
+        t = xpt.Typelib(interfaces=[i])
+        self.checkRoundtrip(t)
+        # tack on some more constants
+        i.constants.append(xpt.Constant("Y",
+                                        xpt.SimpleType(xpt.Type.Tags.int16),
+                                        -30000))
+        i.constants.append(xpt.Constant("Z",
+                                        xpt.SimpleType(xpt.Type.Tags.uint16),
+                                        0xB0B0))
+        i.constants.append(xpt.Constant("A",
+                                        xpt.SimpleType(xpt.Type.Tags.int32),
+                                        -1000000))
+        self.checkRoundtrip(t)
+
+    def test_methods(self):
+        p = xpt.Param(xpt.SimpleType(xpt.Type.Tags.void))
+        m = xpt.Method("Bar", p)
+        i = xpt.Interface("IFoo", iid="11223344-5566-7788-9900-aabbccddeeff",
+                          methods=[m])
+        t = xpt.Typelib(interfaces=[i])
+        self.checkRoundtrip(t)
+        # add some more methods
+        i.methods.append(xpt.Method("One", xpt.Param(xpt.SimpleType(xpt.Type.Tags.int32)),
+                                    params=[
+                                        xpt.Param(xpt.SimpleType(xpt.Type.Tags.int64)),
+                                        xpt.Param(xpt.SimpleType(xpt.Type.Tags.float, pointer=True))
+                                        ]))
+        self.checkRoundtrip(t)
+        # test some other types (should really be more thorough)
+        i.methods.append(xpt.Method("Two", xpt.Param(xpt.SimpleType(xpt.Type.Tags.int32)),
+                                    params=[
+                                        xpt.Param(xpt.SimpleType(xpt.Type.Tags.UTF8String, pointer=True)),
+                                        xpt.Param(xpt.SimpleType(xpt.Type.Tags.wchar_t_ptr, pointer=True))
+                                        ]))
+        self.checkRoundtrip(t)
+        # add a method with an InterfaceType argument
+        bar = xpt.Interface("IBar")
+        t.interfaces.append(bar)
+        i.methods.append(xpt.Method("IFaceMethod", xpt.Param(xpt.SimpleType(xpt.Type.Tags.int32)),
+                                    params=[
+                                        xpt.Param(xpt.InterfaceType(bar))
+                                        ]))
+        self.checkRoundtrip(t)
+
+        # add a method with an InterfaceIsType argument
+        i.methods.append(xpt.Method("IFaceIsMethod", xpt.Param(xpt.SimpleType(xpt.Type.Tags.void)),
+                                    params=[
+                                        xpt.Param(xpt.InterfaceIsType(1)),
+                                        xpt.Param(xpt.SimpleType(xpt.Type.Tags.nsIID))
+                                        ]))
+        self.checkRoundtrip(t)
+
+        # add a method with an ArrayType argument
+        i.methods.append(xpt.Method("ArrayMethod", xpt.Param(xpt.SimpleType(xpt.Type.Tags.void)),
+                                    params=[
+                                        xpt.Param(xpt.ArrayType(
+                                            xpt.SimpleType(xpt.Type.Tags.int32),
+                                            1, 2)),
+                                        xpt.Param(xpt.SimpleType(xpt.Type.Tags.int32)),
+                                        xpt.Param(xpt.SimpleType(xpt.Type.Tags.int32)),
+                                        ]))
+        self.checkRoundtrip(t)
+
+        # add a method with a StringWithSize and WideStringWithSize arguments
+        i.methods.append(xpt.Method("StringWithSizeMethod", xpt.Param(xpt.SimpleType(xpt.Type.Tags.void)),
+                                    params=[
+                                        xpt.Param(xpt.StringWithSizeType(
+                                            1, 2)),
+                                        xpt.Param(xpt.SimpleType(xpt.Type.Tags.int32)),
+                                        xpt.Param(xpt.SimpleType(xpt.Type.Tags.int32)),
+                                        xpt.Param(xpt.WideStringWithSizeType(
+                                            4, 5)),
+                                        xpt.Param(xpt.SimpleType(xpt.Type.Tags.int32)),
+                                        xpt.Param(xpt.SimpleType(xpt.Type.Tags.int32)),
+                                        ]))
+        self.checkRoundtrip(t)
+
+
+class TestInterfaceCmp(unittest.TestCase):
+    def test_unresolvedName(self):
+        """
+        Test comparison function on xpt.Interface by name.
+
+        """
+        i1 = xpt.Interface("ABC")
+        i2 = xpt.Interface("DEF")
+        self.assert_(i1 < i2)
+        self.assert_(i1 != i2)
+
+    def test_unresolvedEqual(self):
+        """
+        Test comparison function on xpt.Interface with equal names and IIDs.
+
+        """
+        i1 = xpt.Interface("ABC")
+        i2 = xpt.Interface("ABC")
+        self.assert_(i1 == i2)
+
+    def test_unresolvedIID(self):
+        """
+        Test comparison function on xpt.Interface with different IIDs.
+
+        """
+        # IIDs sort before names
+        i1 = xpt.Interface("ABC", iid="22334411-5566-7788-9900-aabbccddeeff")
+        i2 = xpt.Interface("DEF", iid="11223344-5566-7788-9900-aabbccddeeff")
+        self.assert_(i2 < i1)
+        self.assert_(i2 != i1)
+
+    def test_unresolvedResolved(self):
+        """
+        Test comparison function on xpt.Interface with interfaces with
+        identical names and IIDs but different resolved status.
+
+        """
+        i1 = xpt.Interface("ABC", iid="11223344-5566-7788-9900-aabbccddeeff")
+        p = xpt.Param(xpt.SimpleType(xpt.Type.Tags.void))
+        m = xpt.Method("Bar", p)
+        i2 = xpt.Interface("ABC", iid="11223344-5566-7788-9900-aabbccddeeff",
+                           methods=[m])
+        self.assert_(i2 < i1)
+        self.assert_(i2 != i1)
+
+    def test_resolvedIdentical(self):
+        """
+        Test comparison function on xpt.Interface with interfaces with
+        identical names and IIDs, both of which are resolved.
+
+        """
+        p = xpt.Param(xpt.SimpleType(xpt.Type.Tags.void))
+        m = xpt.Method("Bar", p)
+        i1 = xpt.Interface("ABC", iid="11223344-5566-7788-9900-aabbccddeeff",
+                           methods=[m])
+        i2 = xpt.Interface("ABC", iid="11223344-5566-7788-9900-aabbccddeeff",
+                           methods=[m])
+        self.assert_(i2 == i1)
+
+
+class TestXPTLink(unittest.TestCase):
+    def test_mergeDifferent(self):
+        """
+        Test that merging two typelibs with completely different interfaces
+        produces the correctly merged typelib.
+
+        """
+        t1 = xpt.Typelib()
+        # add an unresolved interface
+        t1.interfaces.append(xpt.Interface("IFoo", scriptable=True))
+        t2 = xpt.Typelib()
+        # add an unresolved interface
+        t2.interfaces.append(xpt.Interface("IBar", scriptable=True))
+        t3 = xpt.xpt_link([t1, t2])
+
+        self.assertEqual(2, len(t3.interfaces))
+        # Interfaces should wind up sorted
+        self.assertEqual("IBar", t3.interfaces[0].name)
+        self.assertEqual("IFoo", t3.interfaces[1].name)
+
+        # Add some IID values
+        t1 = xpt.Typelib()
+        # add an unresolved interface
+        t1.interfaces.append(xpt.Interface("IFoo", iid="11223344-5566-7788-9900-aabbccddeeff", scriptable=True))
+        t2 = xpt.Typelib()
+        # add an unresolved interface
+        t2.interfaces.append(xpt.Interface("IBar", iid="44332211-6655-8877-0099-aabbccddeeff", scriptable=True))
+        t3 = xpt.xpt_link([t1, t2])
+
+        self.assertEqual(2, len(t3.interfaces))
+        # Interfaces should wind up sorted
+        self.assertEqual("IFoo", t3.interfaces[0].name)
+        self.assertEqual("IBar", t3.interfaces[1].name)
+
+    def test_mergeConflict(self):
+        """
+        Test that merging two typelibs with conflicting interface definitions
+        raises an error.
+
+        """
+        # Same names, different IIDs
+        t1 = xpt.Typelib()
+        # add an unresolved interface
+        t1.interfaces.append(xpt.Interface("IFoo", iid="11223344-5566-7788-9900-aabbccddeeff"))
+        t2 = xpt.Typelib()
+        # add an unresolved interface, same name different IID
+        t2.interfaces.append(xpt.Interface("IFoo", iid="44332211-6655-8877-0099-aabbccddeeff"))
+        self.assertRaises(xpt.DataError, xpt.xpt_link, [t1, t2])
+
+        # Same IIDs, different names
+        t1 = xpt.Typelib()
+        # add an unresolved interface
+        t1.interfaces.append(xpt.Interface("IFoo", iid="11223344-5566-7788-9900-aabbccddeeff"))
+        t2 = xpt.Typelib()
+        # add an unresolved interface, same IID different name
+        t2.interfaces.append(xpt.Interface("IBar", iid="11223344-5566-7788-9900-aabbccddeeff"))
+        self.assertRaises(xpt.DataError, xpt.xpt_link, [t1, t2])
+
+    def test_mergeUnresolvedIID(self):
+        """
+        Test that merging a typelib with an unresolved definition of
+        an interface that's also unresolved in this typelib, but one
+        has a valid IID copies the IID value to the resulting typelib.
+
+        """
+        # Unresolved in both, but t1 has an IID value
+        t1 = xpt.Typelib()
+        # add an unresolved interface with a valid IID
+        t1.interfaces.append(xpt.Interface("IFoo", iid="11223344-5566-7788-9900-aabbccddeeff", scriptable=True))
+        t2 = xpt.Typelib()
+        # add an unresolved interface, no IID
+        t2.interfaces.append(xpt.Interface("IFoo"))
+        t3 = xpt.xpt_link([t1, t2])
+
+        self.assertEqual(1, len(t3.interfaces))
+        self.assertEqual("IFoo", t3.interfaces[0].name)
+        self.assertEqual("11223344-5566-7788-9900-aabbccddeeff", t3.interfaces[0].iid)
+        # Unresolved in both, but t2 has an IID value
+        t1 = xpt.Typelib()
+        # add an unresolved interface, no IID
+        t1.interfaces.append(xpt.Interface("IFoo"))
+        t2 = xpt.Typelib()
+        # add an unresolved interface with a valid IID
+        t2.interfaces.append(xpt.Interface("IFoo", iid="11223344-5566-7788-9900-aabbccddeeff", scriptable=True))
+        t3 = xpt.xpt_link([t1, t2])
+
+        self.assertEqual(1, len(t3.interfaces))
+        self.assertEqual("IFoo", t3.interfaces[0].name)
+        self.assertEqual("11223344-5566-7788-9900-aabbccddeeff", t3.interfaces[0].iid)
+
+    def test_mergeResolvedUnresolved(self):
+        """
+        Test that merging two typelibs, one of which contains an unresolved
+        reference to an interface, and the other of which contains a
+        resolved reference to the same interface results in keeping the
+        resolved reference.
+
+        """
+        # t1 has an unresolved interface, t2 has a resolved version
+        t1 = xpt.Typelib()
+        # add an unresolved interface
+        t1.interfaces.append(xpt.Interface("IFoo"))
+        t2 = xpt.Typelib()
+        # add a resolved interface
+        p = xpt.Param(xpt.SimpleType(xpt.Type.Tags.void))
+        m = xpt.Method("Bar", p)
+        t2.interfaces.append(xpt.Interface("IFoo", iid="11223344-5566-7788-9900-aabbccddeeff",
+                                           methods=[m], scriptable=True))
+        t3 = xpt.xpt_link([t1, t2])
+
+        self.assertEqual(1, len(t3.interfaces))
+        self.assertEqual("IFoo", t3.interfaces[0].name)
+        self.assertEqual("11223344-5566-7788-9900-aabbccddeeff", t3.interfaces[0].iid)
+        self.assert_(t3.interfaces[0].resolved)
+        self.assertEqual(1, len(t3.interfaces[0].methods))
+        self.assertEqual("Bar", t3.interfaces[0].methods[0].name)
+
+        # t1 has a resolved interface, t2 has an unresolved version
+        t1 = xpt.Typelib()
+        # add a resolved interface
+        p = xpt.Param(xpt.SimpleType(xpt.Type.Tags.void))
+        m = xpt.Method("Bar", p)
+        t1.interfaces.append(xpt.Interface("IFoo", iid="11223344-5566-7788-9900-aabbccddeeff",
+                                           methods=[m], scriptable=True))
+        t2 = xpt.Typelib()
+        # add an unresolved interface
+        t2.interfaces.append(xpt.Interface("IFoo"))
+        t3 = xpt.xpt_link([t1, t2])
+
+        self.assertEqual(1, len(t3.interfaces))
+        self.assertEqual("IFoo", t3.interfaces[0].name)
+        self.assertEqual("11223344-5566-7788-9900-aabbccddeeff", t3.interfaces[0].iid)
+        self.assert_(t3.interfaces[0].resolved)
+        self.assertEqual(1, len(t3.interfaces[0].methods))
+        self.assertEqual("Bar", t3.interfaces[0].methods[0].name)
+
+    def test_mergeReplaceParents(self):
+        """
+        Test that merging an interface results in other interfaces' parent
+        member being updated properly.
+
+        """
+        # t1 has an unresolved interface, t2 has a resolved version,
+        # but t1 also has another interface whose parent is the unresolved
+        # interface.
+        t1 = xpt.Typelib()
+        # add an unresolved interface
+        pi = xpt.Interface("IFoo")
+        t1.interfaces.append(pi)
+        # add a child of the unresolved interface
+        t1.interfaces.append(xpt.Interface("IChild", iid="11111111-1111-1111-1111-111111111111",
+                                           resolved=True, parent=pi, scriptable=True))
+        t2 = xpt.Typelib()
+        # add a resolved interface
+        p = xpt.Param(xpt.SimpleType(xpt.Type.Tags.void))
+        m = xpt.Method("Bar", p)
+        t2.interfaces.append(xpt.Interface("IFoo", iid="11223344-5566-7788-9900-aabbccddeeff",
+                                           methods=[m], scriptable=True))
+        t3 = xpt.xpt_link([t1, t2])
+
+        self.assertEqual(2, len(t3.interfaces))
+        self.assertEqual("IChild", t3.interfaces[0].name)
+        self.assertEqual("11111111-1111-1111-1111-111111111111", t3.interfaces[0].iid)
+        self.assertEqual("IFoo", t3.interfaces[1].name)
+        self.assertEqual("11223344-5566-7788-9900-aabbccddeeff", t3.interfaces[1].iid)
+        self.assert_(t3.interfaces[0].resolved)
+        # Ensure that IChild's parent has been updated
+        self.assertEqual(t3.interfaces[1], t3.interfaces[0].parent)
+        self.assert_(t3.interfaces[0].parent.resolved)
+
+        # t1 has a resolved interface, t2 has an unresolved version,
+        # but t2 also has another interface whose parent is the unresolved
+        # interface.
+        t1 = xpt.Typelib()
+        # add a resolved interface
+        p = xpt.Param(xpt.SimpleType(xpt.Type.Tags.void))
+        m = xpt.Method("Bar", p)
+        t1.interfaces.append(xpt.Interface("IFoo", iid="11223344-5566-7788-9900-aabbccddeeff",
+                                           methods=[m], scriptable=True))
+        t2 = xpt.Typelib()
+        # add an unresolved interface
+        pi = xpt.Interface("IFoo")
+        t2.interfaces.append(pi)
+        # add a child of the unresolved interface
+        t2.interfaces.append(xpt.Interface("IChild", iid="11111111-1111-1111-1111-111111111111",
+                                           resolved=True, parent=pi, scriptable=True))
+        t3 = xpt.xpt_link([t1, t2])
+
+        self.assertEqual(2, len(t3.interfaces))
+        self.assertEqual("IChild", t3.interfaces[0].name)
+        self.assertEqual("11111111-1111-1111-1111-111111111111", t3.interfaces[0].iid)
+        self.assertEqual("IFoo", t3.interfaces[1].name)
+        self.assertEqual("11223344-5566-7788-9900-aabbccddeeff", t3.interfaces[1].iid)
+        self.assert_(t3.interfaces[0].resolved)
+        # Ensure that IChild's parent has been updated
+        self.assertEqual(t3.interfaces[1], t3.interfaces[0].parent)
+        self.assert_(t3.interfaces[0].parent.resolved)
+
+    def test_mergeReplaceRetval(self):
+        """
+        Test that merging an interface correctly updates InterfaceType
+        return values on methods of other interfaces.
+
+        """
+        # t1 has an unresolved interface and an interface that uses the
+        # unresolved interface as a return value from a method. t2
+        # has a resolved version of the unresolved interface.
+        t1 = xpt.Typelib()
+        # add an unresolved interface
+        i = xpt.Interface("IFoo")
+        t1.interfaces.append(i)
+        # add an interface that uses the unresolved interface
+        # as a return value in a method.
+        p = xpt.Param(xpt.InterfaceType(i))
+        m = xpt.Method("ReturnIface", p)
+        t1.interfaces.append(xpt.Interface("IRetval", iid="11111111-1111-1111-1111-111111111111",
+                                           methods=[m], scriptable=True))
+        t2 = xpt.Typelib()
+        # add a resolved interface
+        p = xpt.Param(xpt.SimpleType(xpt.Type.Tags.void))
+        m = xpt.Method("Bar", p)
+        t2.interfaces.append(xpt.Interface("IFoo", iid="11223344-5566-7788-9900-aabbccddeeff",
+                                           methods=[m], scriptable=True))
+        t3 = xpt.xpt_link([t1, t2])
+
+        self.assertEqual(2, len(t3.interfaces))
+        self.assertEqual("IRetval", t3.interfaces[0].name)
+        self.assertEqual("11111111-1111-1111-1111-111111111111", t3.interfaces[0].iid)
+        self.assertEqual("IFoo", t3.interfaces[1].name)
+        self.assertEqual("11223344-5566-7788-9900-aabbccddeeff", t3.interfaces[1].iid)
+        self.assert_(t3.interfaces[1].resolved)
+        # Ensure that IRetval's method's return value type has been updated.
+        self.assertEqual(1, len(t3.interfaces[0].methods))
+        self.assert_(t3.interfaces[0].methods[0].result.type.iface.resolved)
+        self.assertEqual(t3.interfaces[1],
+                         t3.interfaces[0].methods[0].result.type.iface)
+
+        # t1 has a resolved interface. t2 has an unresolved version and
+        # an interface that uses the unresolved interface as a return value
+        # from a method.
+        t1 = xpt.Typelib()
+        # add a resolved interface
+        p = xpt.Param(xpt.SimpleType(xpt.Type.Tags.void))
+        m = xpt.Method("Bar", p)
+        t1.interfaces.append(xpt.Interface("IFoo", iid="11223344-5566-7788-9900-aabbccddeeff",
+                                           methods=[m], scriptable=True))
+        t2 = xpt.Typelib()
+        # add an unresolved interface
+        i = xpt.Interface("IFoo")
+        t2.interfaces.append(i)
+        # add an interface that uses the unresolved interface
+        # as a return value in a method.
+        p = xpt.Param(xpt.InterfaceType(i))
+        m = xpt.Method("ReturnIface", p)
+        t2.interfaces.append(xpt.Interface("IRetval", iid="11111111-1111-1111-1111-111111111111",
+                                           methods=[m], scriptable=True))
+        t3 = xpt.xpt_link([t1, t2])
+
+        self.assertEqual(2, len(t3.interfaces))
+        self.assertEqual("IRetval", t3.interfaces[0].name)
+        self.assertEqual("11111111-1111-1111-1111-111111111111", t3.interfaces[0].iid)
+        self.assertEqual("IFoo", t3.interfaces[1].name)
+        self.assertEqual("11223344-5566-7788-9900-aabbccddeeff", t3.interfaces[1].iid)
+        self.assert_(t3.interfaces[1].resolved)
+        # Ensure that IRetval's method's return value type has been updated.
+        self.assertEqual(1, len(t3.interfaces[0].methods))
+        self.assert_(t3.interfaces[0].methods[0].result.type.iface.resolved)
+        self.assertEqual(t3.interfaces[1],
+                         t3.interfaces[0].methods[0].result.type.iface)
+
+    def test_mergeReplaceParams(self):
+        """
+        Test that merging an interface correctly updates InterfaceType
+        params on methods of other interfaces.
+
+        """
+        # t1 has an unresolved interface and an interface that uses the
+        # unresolved interface as a param value in a method. t2
+        # has a resolved version of the unresolved interface.
+        t1 = xpt.Typelib()
+        # add an unresolved interface
+        i = xpt.Interface("IFoo")
+        t1.interfaces.append(i)
+        # add an interface that uses the unresolved interface
+        # as a param value in a method.
+        vp = xpt.Param(xpt.SimpleType(xpt.Type.Tags.void))
+        p = xpt.Param(xpt.InterfaceType(i))
+        m = xpt.Method("IfaceParam", vp, params=[p])
+        t1.interfaces.append(xpt.Interface("IParam", iid="11111111-1111-1111-1111-111111111111",
+                                           methods=[m], scriptable=True))
+        t2 = xpt.Typelib()
+        # add a resolved interface
+        m = xpt.Method("Bar", vp)
+        t2.interfaces.append(xpt.Interface("IFoo", iid="11223344-5566-7788-9900-aabbccddeeff",
+                                           methods=[m], scriptable=True))
+        t3 = xpt.xpt_link([t1, t2])
+
+        self.assertEqual(2, len(t3.interfaces))
+        self.assertEqual("IParam", t3.interfaces[0].name)
+        self.assertEqual("11111111-1111-1111-1111-111111111111", t3.interfaces[0].iid)
+        self.assertEqual("IFoo", t3.interfaces[1].name)
+        self.assertEqual("11223344-5566-7788-9900-aabbccddeeff", t3.interfaces[1].iid)
+        self.assert_(t3.interfaces[1].resolved)
+        # Ensure that IRetval's method's param type has been updated.
+        self.assertEqual(1, len(t3.interfaces[0].methods))
+        self.assert_(t3.interfaces[0].methods[0].params[0].type.iface.resolved)
+        self.assertEqual(t3.interfaces[1],
+                         t3.interfaces[0].methods[0].params[0].type.iface)
+
+        # t1 has a resolved interface. t2 has an unresolved version
+        # and an interface that uses the unresolved interface as a
+        # param value in a method.
+        t1 = xpt.Typelib()
+        # add a resolved interface
+        m = xpt.Method("Bar", vp)
+        t1.interfaces.append(xpt.Interface("IFoo", iid="11223344-5566-7788-9900-aabbccddeeff",
+                                           methods=[m], scriptable=True))
+        t2 = xpt.Typelib()
+        # add an unresolved interface
+        i = xpt.Interface("IFoo")
+        t2.interfaces.append(i)
+        # add an interface that uses the unresolved interface
+        # as a param value in a method.
+        vp = xpt.Param(xpt.SimpleType(xpt.Type.Tags.void))
+        p = xpt.Param(xpt.InterfaceType(i))
+        m = xpt.Method("IfaceParam", vp, params=[p])
+        t2.interfaces.append(xpt.Interface("IParam", iid="11111111-1111-1111-1111-111111111111",
+                                           methods=[m], scriptable=True))
+        t3 = xpt.xpt_link([t1, t2])
+
+        self.assertEqual(2, len(t3.interfaces))
+        self.assertEqual("IParam", t3.interfaces[0].name)
+        self.assertEqual("11111111-1111-1111-1111-111111111111", t3.interfaces[0].iid)
+        self.assertEqual("IFoo", t3.interfaces[1].name)
+        self.assertEqual("11223344-5566-7788-9900-aabbccddeeff", t3.interfaces[1].iid)
+        self.assert_(t3.interfaces[1].resolved)
+        # Ensure that IRetval's method's param type has been updated.
+        self.assertEqual(1, len(t3.interfaces[0].methods))
+        self.assert_(t3.interfaces[0].methods[0].params[0].type.iface.resolved)
+        self.assertEqual(t3.interfaces[1],
+                         t3.interfaces[0].methods[0].params[0].type.iface)
+
+    def test_mergeReplaceArrayTypeParams(self):
+        """
+        Test that merging an interface correctly updates ArrayType
+        params whose element_type is an InterfaceType on methods
+        of other interfaces.
+
+        """
+        # t1 has an unresolved interface and an interface that uses the
+        # unresolved interface as a type in an ArrayType in a parameter
+        # of a method. t2 has a resolved version of the unresolved interface.
+        t1 = xpt.Typelib()
+        # add an unresolved interface
+        i = xpt.Interface("IFoo")
+        t1.interfaces.append(i)
+        # add an interface that uses the unresolved interface
+        # as a type in an ArrayType in a param value in a method.
+        vp = xpt.Param(xpt.SimpleType(xpt.Type.Tags.void))
+        intp = xpt.Param(xpt.SimpleType(xpt.Type.Tags.int32))
+        p = xpt.Param(xpt.ArrayType(xpt.InterfaceType(i), 1, 2))
+        m = xpt.Method("ArrayIfaceParam", vp, params=[p, intp, intp])
+        t1.interfaces.append(xpt.Interface("IParam", iid="11111111-1111-1111-1111-111111111111",
+                                           methods=[m], scriptable=True))
+        t2 = xpt.Typelib()
+        # add a resolved interface
+        m = xpt.Method("Bar", vp)
+        t2.interfaces.append(xpt.Interface("IFoo", iid="11223344-5566-7788-9900-aabbccddeeff",
+                                           methods=[m], scriptable=True))
+        t3 = xpt.xpt_link([t1, t2])
+
+        self.assertEqual(2, len(t3.interfaces))
+        self.assertEqual("IParam", t3.interfaces[0].name)
+        self.assertEqual("11111111-1111-1111-1111-111111111111", t3.interfaces[0].iid)
+        self.assertEqual("IFoo", t3.interfaces[1].name)
+        self.assertEqual("11223344-5566-7788-9900-aabbccddeeff", t3.interfaces[1].iid)
+        self.assert_(t3.interfaces[1].resolved)
+        # Ensure that IRetval's method's param type has been updated.
+        self.assertEqual(1, len(t3.interfaces[0].methods))
+        self.assert_(t3.interfaces[0].methods[0].params[0].type.element_type.iface.resolved)
+        self.assertEqual(t3.interfaces[1],
+                         t3.interfaces[0].methods[0].params[0].type.element_type.iface)
+
+if __name__ == '__main__':
+    mozunit.main()
diff --git a/xpcom/typelib/xpt/tools/xpt.py b/xpcom/typelib/xpt/tools/xpt.py
new file mode 100755
index 000000000..67d40f7b2
--- /dev/null
+++ b/xpcom/typelib/xpt/tools/xpt.py
@@ -0,0 +1,1540 @@
+#!/usr/bin/env python
+# Copyright 2010,2011 Mozilla Foundation. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#   1. Redistributions of source code must retain the above copyright
+#      notice, this list of conditions and the following disclaimer.
+#
+#   2. Redistributions in binary form must reproduce the above copyright
+#      notice, this list of conditions and the following disclaimer in
+#      the documentation and/or other materials provided with the
+#      distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE MOZILLA FOUNDATION ``AS IS'' AND ANY
+# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE MOZILLA FOUNDATION OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+# OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# The views and conclusions contained in the software and documentation
+# are those of the authors and should not be interpreted as representing
+# official policies, either expressed or implied, of the Mozilla
+# Foundation.
+
+"""
+A module for working with XPCOM Type Libraries.
+
+The XPCOM Type Library File Format is described at:
+http://www.mozilla.org/scriptable/typelib_file.html . It is used
+to provide type information for calling methods on XPCOM objects
+from scripting languages such as JavaScript.
+
+This module provides a set of classes representing the parts of
+a typelib in a high-level manner, as well as methods for reading
+and writing them from files.
+
+The usable public interfaces are currently:
+Typelib.read(input_file) - read a typelib from a file on disk or file-like
+                           object, return a Typelib object.
+
+xpt_dump(filename)     - read a typelib from a file on disk, dump
+                         the contents to stdout in a human-readable
+                         format.
+
+Typelib()              - construct a new Typelib object
+Interface()            - construct a new Interface object
+Method()               - construct a new object representing a method
+                         defined on an Interface
+Constant()             - construct a new object representing a constant
+                         defined on an Interface
+Param()                - construct a new object representing a parameter
+                         to a method
+SimpleType()           - construct a new object representing a simple
+                         data type
+InterfaceType()        - construct a new object representing a type that
+                         is an IDL-defined interface
+
+"""
+
+from __future__ import with_statement
+import os
+import sys
+import struct
+import operator
+
+# header magic
+XPT_MAGIC = "XPCOM\nTypeLib\r\n\x1a"
+TYPELIB_VERSION = (1, 2)
+
+
+class FileFormatError(Exception):
+    pass
+
+
+class DataError(Exception):
+    pass
+
+
+# Magic for creating enums
+def M_add_class_attribs(attribs):
+    def foo(name, bases, dict_):
+        for v, k in attribs:
+            dict_[k] = v
+        return type(name, bases, dict_)
+    return foo
+
+
+def enum(*names):
+    class Foo(object):
+        __metaclass__ = M_add_class_attribs(enumerate(names))
+
+        def __setattr__(self, name, value):  # this makes it read-only
+            raise NotImplementedError
+    return Foo()
+
+
+# Descriptor types as described in the spec
+class Type(object):
+    """
+    Data type of a method parameter or return value. Do not instantiate
+    this class directly. Rather, use one of its subclasses.
+
+    """
+    _prefixdescriptor = struct.Struct(">B")
+    Tags = enum(
+        # The first 18 entries are SimpleTypeDescriptor
+        'int8',
+        'int16',
+        'int32',
+        'int64',
+        'uint8',
+        'uint16',
+        'uint32',
+        'uint64',
+        'float',
+        'double',
+        'boolean',
+        'char',
+        'wchar_t',
+        'void',
+        # the following four values are only valid as pointers
+        'nsIID',
+        'DOMString',
+        'char_ptr',
+        'wchar_t_ptr',
+        # InterfaceTypeDescriptor
+        'Interface',
+        # InterfaceIsTypeDescriptor
+        'InterfaceIs',
+        # ArrayTypeDescriptor
+        'Array',
+        # StringWithSizeTypeDescriptor
+        'StringWithSize',
+        # WideStringWithSizeTypeDescriptor
+        'WideStringWithSize',
+        # XXX: These are also SimpleTypes (but not in the spec)
+        # http://hg.mozilla.org/mozilla-central/annotate/0e0e2516f04e/xpcom/typelib/xpt/tools/xpt_dump.c#l69
+        'UTF8String',
+        'CString',
+        'AString',
+        'jsval',
+        )
+
+    def __init__(self, pointer=False, reference=False):
+        self.pointer = pointer
+        self.reference = reference
+        if reference and not pointer:
+            raise Exception("If reference is True pointer must be True too")
+
+    def __cmp__(self, other):
+        return (
+            # First make sure we have two Types of the same type (no pun intended!)
+            cmp(type(self), type(other)) or
+            cmp(self.pointer, other.pointer) or
+            cmp(self.reference, other.reference)
+        )
+
+    @staticmethod
+    def decodeflags(byte):
+        """
+        Given |byte|, an unsigned uint8 containing flag bits,
+        decode the flag bits as described in
+        http://www.mozilla.org/scriptable/typelib_file.html#TypeDescriptor
+        and return a dict of flagname: (True|False) suitable
+        for passing to Type.__init__ as **kwargs.
+
+        """
+        return {'pointer': bool(byte & 0x80),
+                'reference': bool(byte & 0x20),
+                }
+
+    def encodeflags(self):
+        """
+        Encode the flag bits of this Type object. Returns a byte.
+
+        """
+        flags = 0
+        if self.pointer:
+            flags |= 0x80
+        if self.reference:
+            flags |= 0x20
+        return flags
+
+    @staticmethod
+    def read(typelib, map, data_pool, offset):
+        """
+        Read a TypeDescriptor at |offset| from the mmaped file |map| with
+        data pool offset |data_pool|. Returns (Type, next offset),
+        where |next offset| is an offset suitable for reading the data
+        following this TypeDescriptor.
+
+        """
+        start = data_pool + offset - 1
+        (data,) = Type._prefixdescriptor.unpack_from(map, start)
+        # first three bits are the flags
+        flags = data & 0xE0
+        flags = Type.decodeflags(flags)
+        # last five bits is the tag
+        tag = data & 0x1F
+        offset += Type._prefixdescriptor.size
+        t = None
+        if tag <= Type.Tags.wchar_t_ptr or tag >= Type.Tags.UTF8String:
+            t = SimpleType.get(data, tag, flags)
+        elif tag == Type.Tags.Interface:
+            t, offset = InterfaceType.read(typelib, map, data_pool, offset, flags)
+        elif tag == Type.Tags.InterfaceIs:
+            t, offset = InterfaceIsType.read(typelib, map, data_pool, offset, flags)
+        elif tag == Type.Tags.Array:
+            t, offset = ArrayType.read(typelib, map, data_pool, offset, flags)
+        elif tag == Type.Tags.StringWithSize:
+            t, offset = StringWithSizeType.read(typelib, map, data_pool, offset, flags)
+        elif tag == Type.Tags.WideStringWithSize:
+            t, offset = WideStringWithSizeType.read(typelib, map, data_pool, offset, flags)
+        return t, offset
+
+    def write(self, typelib, file):
+        """
+        Write a TypeDescriptor to |file|, which is assumed
+        to be seeked to the proper position. For types other than
+        SimpleType, this is not sufficient for writing the TypeDescriptor,
+        and the subclass method must be called.
+
+        """
+        file.write(Type._prefixdescriptor.pack(self.encodeflags() | self.tag))
+
+
+class SimpleType(Type):
+    """
+    A simple data type. (SimpleTypeDescriptor from the typelib specification.)
+
+    """
+    _cache = {}
+
+    def __init__(self, tag, **kwargs):
+        Type.__init__(self, **kwargs)
+        self.tag = tag
+
+    def __cmp__(self, other):
+        return (
+            Type.__cmp__(self, other) or
+            cmp(self.tag, other.tag)
+        )
+
+    @staticmethod
+    def get(data, tag, flags):
+        """
+        Get a SimpleType object representing |data| (a TypeDescriptorPrefix).
+        May return an already-created object. If no cached object is found,
+        construct one with |tag| and |flags|.
+
+        """
+        if data not in SimpleType._cache:
+            SimpleType._cache[data] = SimpleType(tag, **flags)
+        return SimpleType._cache[data]
+
+    def __str__(self):
+        s = "unknown"
+        if self.tag == Type.Tags.char_ptr and self.pointer:
+            return "string"
+        if self.tag == Type.Tags.wchar_t_ptr and self.pointer:
+            return "wstring"
+        for t in dir(Type.Tags):
+            if self.tag == getattr(Type.Tags, t):
+                s = t
+                break
+
+        if self.pointer:
+            if self.reference:
+                s += " &"
+            else:
+                s += " *"
+        return s
+
+
+class InterfaceType(Type):
+    """
+    A type representing a pointer to an IDL-defined interface.
+    (InterfaceTypeDescriptor from the typelib specification.)
+
+    """
+    _descriptor = struct.Struct(">H")
+
+    def __init__(self, iface, pointer=True, **kwargs):
+        if not pointer:
+            raise DataError("InterfaceType is not valid with pointer=False")
+        Type.__init__(self, pointer=pointer, **kwargs)
+        self.iface = iface
+        self.tag = Type.Tags.Interface
+
+    def __cmp__(self, other):
+        return (
+            Type.__cmp__(self, other) or
+            # When comparing interface types, only look at the name.
+            cmp(self.iface.name, other.iface.name) or
+            cmp(self.tag, other.tag)
+        )
+
+    @staticmethod
+    def read(typelib, map, data_pool, offset, flags):
+        """
+        Read an InterfaceTypeDescriptor at |offset| from the mmaped
+        file |map| with data pool offset |data_pool|.
+        Returns (InterfaceType, next offset),
+        where |next offset| is an offset suitable for reading the data
+        following this InterfaceTypeDescriptor.
+
+        """
+        if not flags['pointer']:
+            return None, offset
+        start = data_pool + offset - 1
+        (iface_index,) = InterfaceType._descriptor.unpack_from(map, start)
+        offset += InterfaceType._descriptor.size
+        iface = None
+        # interface indices are 1-based
+        if iface_index > 0 and iface_index <= len(typelib.interfaces):
+            iface = typelib.interfaces[iface_index - 1]
+        return InterfaceType(iface, **flags), offset
+
+    def write(self, typelib, file):
+        """
+        Write an InterfaceTypeDescriptor to |file|, which is assumed
+        to be seeked to the proper position.
+
+        """
+        Type.write(self, typelib, file)
+        # write out the interface index (1-based)
+        file.write(InterfaceType._descriptor.pack(typelib.interfaces.index(self.iface) + 1))
+
+    def __str__(self):
+        if self.iface:
+            return self.iface.name
+        return "unknown interface"
+
+
+class InterfaceIsType(Type):
+    """
+    A type representing an interface described by one of the other
+    arguments to the method. (InterfaceIsTypeDescriptor from the
+    typelib specification.)
+
+    """
+    _descriptor = struct.Struct(">B")
+    _cache = {}
+
+    def __init__(self, param_index, pointer=True, **kwargs):
+        if not pointer:
+            raise DataError("InterfaceIsType is not valid with pointer=False")
+        Type.__init__(self, pointer=pointer, **kwargs)
+        self.param_index = param_index
+        self.tag = Type.Tags.InterfaceIs
+
+    def __cmp__(self, other):
+        return (
+            Type.__cmp__(self, other) or
+            cmp(self.param_index, other.param_index) or
+            cmp(self.tag, other.tag)
+        )
+
+    @staticmethod
+    def read(typelib, map, data_pool, offset, flags):
+        """
+        Read an InterfaceIsTypeDescriptor at |offset| from the mmaped
+        file |map| with data pool offset |data_pool|.
+        Returns (InterfaceIsType, next offset),
+        where |next offset| is an offset suitable for reading the data
+        following this InterfaceIsTypeDescriptor.
+        May return a cached value.
+
+        """
+        if not flags['pointer']:
+            return None, offset
+        start = data_pool + offset - 1
+        (param_index,) = InterfaceIsType._descriptor.unpack_from(map, start)
+        offset += InterfaceIsType._descriptor.size
+        if param_index not in InterfaceIsType._cache:
+            InterfaceIsType._cache[param_index] = InterfaceIsType(param_index, **flags)
+        return InterfaceIsType._cache[param_index], offset
+
+    def write(self, typelib, file):
+        """
+        Write an InterfaceIsTypeDescriptor to |file|, which is assumed
+        to be seeked to the proper position.
+
+        """
+        Type.write(self, typelib, file)
+        file.write(InterfaceIsType._descriptor.pack(self.param_index))
+
+    def __str__(self):
+        return "InterfaceIs *"
+
+
+class ArrayType(Type):
+    """
+    A type representing an Array of elements of another type, whose
+    size and length are passed as separate parameters to a method.
+    (ArrayTypeDescriptor from the typelib specification.)
+
+    """
+    _descriptor = struct.Struct(">BB")
+
+    def __init__(self, element_type, size_is_arg_num, length_is_arg_num,
+                 pointer=True, **kwargs):
+        if not pointer:
+            raise DataError("ArrayType is not valid with pointer=False")
+        Type.__init__(self, pointer=pointer, **kwargs)
+        self.element_type = element_type
+        self.size_is_arg_num = size_is_arg_num
+        self.length_is_arg_num = length_is_arg_num
+        self.tag = Type.Tags.Array
+
+    def __cmp__(self, other):
+        return (
+            Type.__cmp__(self, other) or
+            cmp(self.element_type, other.element_type) or
+            cmp(self.size_is_arg_num, other.size_is_arg_num) or
+            cmp(self.length_is_arg_num, other.length_is_arg_num) or
+            cmp(self.tag, other.tag)
+        )
+
+    @staticmethod
+    def read(typelib, map, data_pool, offset, flags):
+        """
+        Read an ArrayTypeDescriptor at |offset| from the mmaped
+        file |map| with data pool offset |data_pool|.
+        Returns (ArrayType, next offset),
+        where |next offset| is an offset suitable for reading the data
+        following this ArrayTypeDescriptor.
+        """
+        if not flags['pointer']:
+            return None, offset
+        start = data_pool + offset - 1
+        (size_is_arg_num, length_is_arg_num) = ArrayType._descriptor.unpack_from(map, start)
+        offset += ArrayType._descriptor.size
+        t, offset = Type.read(typelib, map, data_pool, offset)
+        return ArrayType(t, size_is_arg_num, length_is_arg_num, **flags), offset
+
+    def write(self, typelib, file):
+        """
+        Write an ArrayTypeDescriptor to |file|, which is assumed
+        to be seeked to the proper position.
+
+        """
+        Type.write(self, typelib, file)
+        file.write(ArrayType._descriptor.pack(self.size_is_arg_num,
+                                              self.length_is_arg_num))
+        self.element_type.write(typelib, file)
+
+    def __str__(self):
+        return "%s []" % str(self.element_type)
+
+
+class StringWithSizeType(Type):
+    """
+    A type representing a UTF-8 encoded string whose size and length
+    are passed as separate arguments to a method. (StringWithSizeTypeDescriptor
+    from the typelib specification.)
+
+    """
+    _descriptor = struct.Struct(">BB")
+
+    def __init__(self, size_is_arg_num, length_is_arg_num,
+                 pointer=True, **kwargs):
+        if not pointer:
+            raise DataError("StringWithSizeType is not valid with pointer=False")
+        Type.__init__(self, pointer=pointer, **kwargs)
+        self.size_is_arg_num = size_is_arg_num
+        self.length_is_arg_num = length_is_arg_num
+        self.tag = Type.Tags.StringWithSize
+
+    def __cmp__(self, other):
+        return (
+            Type.__cmp__(self, other) or
+            cmp(self.size_is_arg_num, other.size_is_arg_num) or
+            cmp(self.length_is_arg_num, other.length_is_arg_num) or
+            cmp(self.tag, other.tag)
+        )
+
+    @staticmethod
+    def read(typelib, map, data_pool, offset, flags):
+        """
+        Read an StringWithSizeTypeDescriptor at |offset| from the mmaped
+        file |map| with data pool offset |data_pool|.
+        Returns (StringWithSizeType, next offset),
+        where |next offset| is an offset suitable for reading the data
+        following this StringWithSizeTypeDescriptor.
+        """
+        if not flags['pointer']:
+            return None, offset
+        start = data_pool + offset - 1
+        (size_is_arg_num, length_is_arg_num) = StringWithSizeType._descriptor.unpack_from(map, start)
+        offset += StringWithSizeType._descriptor.size
+        return StringWithSizeType(size_is_arg_num, length_is_arg_num, **flags), offset
+
+    def write(self, typelib, file):
+        """
+        Write a StringWithSizeTypeDescriptor to |file|, which is assumed
+        to be seeked to the proper position.
+
+        """
+        Type.write(self, typelib, file)
+        file.write(StringWithSizeType._descriptor.pack(self.size_is_arg_num,
+                                                       self.length_is_arg_num))
+
+    def __str__(self):
+        return "string_s"
+
+
+class WideStringWithSizeType(Type):
+    """
+    A type representing a UTF-16 encoded string whose size and length
+    are passed as separate arguments to a method.
+    (WideStringWithSizeTypeDescriptor from the typelib specification.)
+
+    """
+    _descriptor = struct.Struct(">BB")
+
+    def __init__(self, size_is_arg_num, length_is_arg_num,
+                 pointer=True, **kwargs):
+        if not pointer:
+            raise DataError("WideStringWithSizeType is not valid with pointer=False")
+        Type.__init__(self, pointer=pointer, **kwargs)
+        self.size_is_arg_num = size_is_arg_num
+        self.length_is_arg_num = length_is_arg_num
+        self.tag = Type.Tags.WideStringWithSize
+
+    def __cmp__(self, other):
+        return (
+            Type.__cmp__(self, other) or
+            cmp(self.size_is_arg_num, other.size_is_arg_num) or
+            cmp(self.length_is_arg_num, other.length_is_arg_num) or
+            cmp(self.tag, other.tag)
+        )
+
+    @staticmethod
+    def read(typelib, map, data_pool, offset, flags):
+        """
+        Read an WideStringWithSizeTypeDescriptor at |offset| from the mmaped
+        file |map| with data pool offset |data_pool|.
+        Returns (WideStringWithSizeType, next offset),
+        where |next offset| is an offset suitable for reading the data
+        following this WideStringWithSizeTypeDescriptor.
+        """
+        if not flags['pointer']:
+            return None, offset
+        start = data_pool + offset - 1
+        (size_is_arg_num, length_is_arg_num) = WideStringWithSizeType._descriptor.unpack_from(map, start)
+        offset += WideStringWithSizeType._descriptor.size
+        return WideStringWithSizeType(size_is_arg_num, length_is_arg_num, **flags), offset
+
+    def write(self, typelib, file):
+        """
+        Write a WideStringWithSizeTypeDescriptor to |file|, which is assumed
+        to be seeked to the proper position.
+
+        """
+        Type.write(self, typelib, file)
+        file.write(WideStringWithSizeType._descriptor.pack(self.size_is_arg_num,
+                                                           self.length_is_arg_num))
+
+    def __str__(self):
+        return "wstring_s"
+
+
+class Param(object):
+    """
+    A parameter to a method, or the return value of a method.
+    (ParamDescriptor from the typelib specification.)
+
+    """
+    _descriptorstart = struct.Struct(">B")
+
+    def __init__(self, type, in_=True, out=False, retval=False,
+                 shared=False, dipper=False, optional=False):
+        """
+        Construct a Param object with the specified |type| and
+        flags. Params default to "in".
+
+        """
+
+        self.type = type
+        self.in_ = in_
+        self.out = out
+        self.retval = retval
+        self.shared = shared
+        self.dipper = dipper
+        self.optional = optional
+
+    def __cmp__(self, other):
+        return (
+            cmp(self.type, other.type) or
+            cmp(self.in_, other.in_) or
+            cmp(self.out, other.out) or
+            cmp(self.retval, other.retval) or
+            cmp(self.shared, other.shared) or
+            cmp(self.dipper, other.dipper) or
+            cmp(self.optional, other.optional)
+        )
+
+    @staticmethod
+    def decodeflags(byte):
+        """
+        Given |byte|, an unsigned uint8 containing flag bits,
+        decode the flag bits as described in
+        http://www.mozilla.org/scriptable/typelib_file.html#ParamDescriptor
+        and return a dict of flagname: (True|False) suitable
+        for passing to Param.__init__ as **kwargs
+        """
+        return {'in_': bool(byte & 0x80),
+                'out': bool(byte & 0x40),
+                'retval': bool(byte & 0x20),
+                'shared': bool(byte & 0x10),
+                'dipper': bool(byte & 0x08),
+                # XXX: Not in the spec, see:
+                # http://hg.mozilla.org/mozilla-central/annotate/0e0e2516f04e/xpcom/typelib/xpt/public/xpt_struct.h#l456
+                'optional': bool(byte & 0x04),
+                }
+
+    def encodeflags(self):
+        """
+        Encode the flags of this Param. Return a byte suitable for
+        writing to a typelib file.
+
+        """
+        flags = 0
+        if self.in_:
+            flags |= 0x80
+        if self.out:
+            flags |= 0x40
+        if self.retval:
+            flags |= 0x20
+        if self.shared:
+            flags |= 0x10
+        if self.dipper:
+            flags |= 0x08
+        if self.optional:
+            flags |= 0x04
+        return flags
+
+    @staticmethod
+    def read(typelib, map, data_pool, offset):
+        """
+        Read a ParamDescriptor at |offset| from the mmaped file |map| with
+        data pool offset |data_pool|. Returns (Param, next offset),
+        where |next offset| is an offset suitable for reading the data
+        following this ParamDescriptor.
+        """
+        start = data_pool + offset - 1
+        (flags,) = Param._descriptorstart.unpack_from(map, start)
+        # only the first five bits are flags
+        flags &= 0xFC
+        flags = Param.decodeflags(flags)
+        offset += Param._descriptorstart.size
+        t, offset = Type.read(typelib, map, data_pool, offset)
+        p = Param(t, **flags)
+        return p, offset
+
+    def write(self, typelib, file):
+        """
+        Write a ParamDescriptor to |file|, which is assumed to be seeked
+        to the correct position.
+
+        """
+        file.write(Param._descriptorstart.pack(self.encodeflags()))
+        self.type.write(typelib, file)
+
+    def prefix(self):
+        """
+        Return a human-readable string representing the flags set
+        on this Param.
+
+        """
+        s = ""
+        if self.out:
+            if self.in_:
+                s = "inout "
+            else:
+                s = "out "
+        else:
+            s = "in "
+        if self.dipper:
+            s += "dipper "
+        if self.retval:
+            s += "retval "
+        if self.shared:
+            s += "shared "
+        if self.optional:
+            s += "optional "
+        return s
+
+    def __str__(self):
+        return self.prefix() + str(self.type)
+
+
+class Method(object):
+    """
+    A method of an interface, defining its associated parameters
+    and return value.
+    (MethodDescriptor from the typelib specification.)
+
+    """
+    _descriptorstart = struct.Struct(">BIB")
+
+    def __init__(self, name, result,
+                 params=[], getter=False, setter=False, notxpcom=False,
+                 constructor=False, hidden=False, optargc=False,
+                 implicit_jscontext=False):
+        self.name = name
+        self._name_offset = 0
+        self.getter = getter
+        self.setter = setter
+        self.notxpcom = notxpcom
+        self.constructor = constructor
+        self.hidden = hidden
+        self.optargc = optargc
+        self.implicit_jscontext = implicit_jscontext
+        self.params = list(params)
+        if result and not isinstance(result, Param):
+            raise Exception("result must be a Param!")
+        self.result = result
+
+    def __cmp__(self, other):
+        return (
+            cmp(self.name, other.name) or
+            cmp(self.getter, other.getter) or
+            cmp(self.setter, other.setter) or
+            cmp(self.notxpcom, other.notxpcom) or
+            cmp(self.constructor, other.constructor) or
+            cmp(self.hidden, other.hidden) or
+            cmp(self.optargc, other.optargc) or
+            cmp(self.implicit_jscontext, other.implicit_jscontext) or
+            cmp(self.params, other.params) or
+            cmp(self.result, other.result)
+        )
+
+    def read_params(self, typelib, map, data_pool, offset, num_args):
+        """
+        Read |num_args| ParamDescriptors representing this Method's arguments
+        from the mmaped file |map| with data pool at the offset |data_pool|,
+        starting at |offset| into self.params. Returns the offset
+        suitable for reading the data following the ParamDescriptor array.
+
+        """
+        for i in range(num_args):
+            p, offset = Param.read(typelib, map, data_pool, offset)
+            self.params.append(p)
+        return offset
+
+    def read_result(self, typelib, map, data_pool, offset):
+        """
+        Read a ParamDescriptor representing this Method's return type
+        from the mmaped file |map| with data pool at the offset |data_pool|,
+        starting at |offset| into self.result. Returns the offset
+        suitable for reading the data following the ParamDescriptor.
+
+        """
+        self.result, offset = Param.read(typelib, map, data_pool, offset)
+        return offset
+
+    @staticmethod
+    def decodeflags(byte):
+        """
+        Given |byte|, an unsigned uint8 containing flag bits,
+        decode the flag bits as described in
+        http://www.mozilla.org/scriptable/typelib_file.html#MethodDescriptor
+        and return a dict of flagname: (True|False) suitable
+        for passing to Method.__init__ as **kwargs
+
+        """
+        return {'getter': bool(byte & 0x80),
+                'setter': bool(byte & 0x40),
+                'notxpcom': bool(byte & 0x20),
+                'constructor': bool(byte & 0x10),
+                'hidden': bool(byte & 0x08),
+                # Not in the spec, see
+                # http://hg.mozilla.org/mozilla-central/annotate/0e0e2516f04e/xpcom/typelib/xpt/public/xpt_struct.h#l489
+                'optargc': bool(byte & 0x04),
+                'implicit_jscontext': bool(byte & 0x02),
+                }
+
+    def encodeflags(self):
+        """
+        Encode the flags of this Method object, return a byte suitable
+        for writing to a typelib file.
+
+        """
+        flags = 0
+        if self.getter:
+            flags |= 0x80
+        if self.setter:
+            flags |= 0x40
+        if self.notxpcom:
+            flags |= 0x20
+        if self.constructor:
+            flags |= 0x10
+        if self.hidden:
+            flags |= 0x08
+        if self.optargc:
+            flags |= 0x04
+        if self.implicit_jscontext:
+            flags |= 0x02
+        return flags
+
+    @staticmethod
+    def read(typelib, map, data_pool, offset):
+        """
+        Read a MethodDescriptor at |offset| from the mmaped file |map| with
+        data pool offset |data_pool|. Returns (Method, next offset),
+        where |next offset| is an offset suitable for reading the data
+        following this MethodDescriptor.
+
+        """
+        start = data_pool + offset - 1
+        flags, name_offset, num_args = Method._descriptorstart.unpack_from(map, start)
+        # only the first seven bits are flags
+        flags &= 0xFE
+        flags = Method.decodeflags(flags)
+        name = Typelib.read_string(map, data_pool, name_offset)
+        m = Method(name, None, **flags)
+        offset += Method._descriptorstart.size
+        offset = m.read_params(typelib, map, data_pool, offset, num_args)
+        offset = m.read_result(typelib, map, data_pool, offset)
+        return m, offset
+
+    def write(self, typelib, file):
+        """
+        Write a MethodDescriptor to |file|, which is assumed to be
+        seeked to the right position.
+
+        """
+        file.write(Method._descriptorstart.pack(self.encodeflags(),
+                                                self._name_offset,
+                                                len(self.params)))
+        for p in self.params:
+            p.write(typelib, file)
+        self.result.write(typelib, file)
+
+    def write_name(self, file, data_pool_offset):
+        """
+        Write this method's name to |file|.
+        Assumes that |file| is currently seeked to an unused portion
+        of the data pool.
+
+        """
+        if self.name:
+            self._name_offset = file.tell() - data_pool_offset + 1
+            file.write(self.name + "\x00")
+        else:
+            self._name_offset = 0
+
+
+class Constant(object):
+    """
+    A constant value of a specific type defined on an interface.
+    (ConstantDesciptor from the typelib specification.)
+
+    """
+    _descriptorstart = struct.Struct(">I")
+    # Actual value is restricted to this set of types
+    # XXX: the spec lies, the source allows a bunch more
+    # http://hg.mozilla.org/mozilla-central/annotate/9c85f9aaec8c/xpcom/typelib/xpt/src/xpt_struct.c#l689
+    typemap = {Type.Tags.int16: '>h',
+               Type.Tags.uint16: '>H',
+               Type.Tags.int32: '>i',
+               Type.Tags.uint32: '>I'}
+
+    def __init__(self, name, type, value):
+        self.name = name
+        self._name_offset = 0
+        self.type = type
+        self.value = value
+
+    def __cmp__(self, other):
+        return (
+            cmp(self.name, other.name) or
+            cmp(self.type, other.type) or
+            cmp(self.value, other.value)
+        )
+
+    @staticmethod
+    def read(typelib, map, data_pool, offset):
+        """
+        Read a ConstDescriptor at |offset| from the mmaped file |map| with
+        data pool offset |data_pool|. Returns (Constant, next offset),
+        where |next offset| is an offset suitable for reading the data
+        following this ConstDescriptor.
+
+        """
+        start = data_pool + offset - 1
+        (name_offset,) = Constant._descriptorstart.unpack_from(map, start)
+        name = Typelib.read_string(map, data_pool, name_offset)
+        offset += Constant._descriptorstart.size
+        # Read TypeDescriptor
+        t, offset = Type.read(typelib, map, data_pool, offset)
+        c = None
+        if isinstance(t, SimpleType) and t.tag in Constant.typemap:
+            tt = Constant.typemap[t.tag]
+            start = data_pool + offset - 1
+            (val,) = struct.unpack_from(tt, map, start)
+            offset += struct.calcsize(tt)
+            c = Constant(name, t, val)
+        return c, offset
+
+    def write(self, typelib, file):
+        """
+        Write a ConstDescriptor to |file|, which is assumed
+        to be seeked to the proper position.
+
+        """
+        file.write(Constant._descriptorstart.pack(self._name_offset))
+        self.type.write(typelib, file)
+        tt = Constant.typemap[self.type.tag]
+        file.write(struct.pack(tt, self.value))
+
+    def write_name(self, file, data_pool_offset):
+        """
+        Write this constants's name to |file|.
+        Assumes that |file| is currently seeked to an unused portion
+        of the data pool.
+
+        """
+        if self.name:
+            self._name_offset = file.tell() - data_pool_offset + 1
+            file.write(self.name + "\x00")
+        else:
+            self._name_offset = 0
+
+    def __repr__(self):
+        return "Constant(%s, %s, %d)" % (self.name, str(self.type), self.value)
+
+
+class Interface(object):
+    """
+    An Interface represents an object, with its associated methods
+    and constant values.
+    (InterfaceDescriptor from the typelib specification.)
+
+    """
+    _direntry = struct.Struct(">16sIII")
+    _descriptorstart = struct.Struct(">HH")
+
+    UNRESOLVED_IID = "00000000-0000-0000-0000-000000000000"
+
+    def __init__(self, name, iid=UNRESOLVED_IID, namespace="",
+                 resolved=False, parent=None, methods=[], constants=[],
+                 scriptable=False, function=False, builtinclass=False,
+                 main_process_scriptable_only=False):
+        self.resolved = resolved
+        # TODO: should validate IIDs!
+        self.iid = iid
+        self.name = name
+        self.namespace = namespace
+        # if unresolved, all the members following this are unusable
+        self.parent = parent
+        self.methods = list(methods)
+        self.constants = list(constants)
+        self.scriptable = scriptable
+        self.function = function
+        self.builtinclass = builtinclass
+        self.main_process_scriptable_only = main_process_scriptable_only
+        # For sanity, if someone constructs an Interface and passes
+        # in methods or constants, then it's resolved.
+        if self.methods or self.constants:
+            # make sure it has a valid IID
+            if self.iid == Interface.UNRESOLVED_IID:
+                raise DataError("Cannot instantiate Interface %s containing methods or constants with an unresolved IID" % self.name)
+            self.resolved = True
+        # These are only used for writing out the interface
+        self._descriptor_offset = 0
+        self._name_offset = 0
+        self._namespace_offset = 0
+        self.xpt_filename = None
+
+    def __repr__(self):
+        return "Interface('%s', '%s', '%s', methods=%s)" % (self.name, self.iid, self.namespace, self.methods)
+
+    def __str__(self):
+        return "Interface(name='%s', iid='%s')" % (self.name, self.iid)
+
+    def __hash__(self):
+        return hash((self.name, self.iid))
+
+    def __cmp__(self, other):
+        c = cmp(self.iid, other.iid)
+        if c != 0:
+            return c
+        c = cmp(self.name, other.name)
+        if c != 0:
+            return c
+        c = cmp(self.namespace, other.namespace)
+        if c != 0:
+            return c
+        # names and IIDs are the same, check resolved
+        if self.resolved != other.resolved:
+            if self.resolved:
+                return -1
+            else:
+                return 1
+        else:
+            if not self.resolved:
+                # both unresolved, but names and IIDs are the same, so equal
+                return 0
+        # When comparing parents, only look at the name.
+        if (self.parent is None) != (other.parent is None):
+            if self.parent is None:
+                return -1
+            else:
+                return 1
+        elif self.parent is not None:
+            c = cmp(self.parent.name, other.parent.name)
+            if c != 0:
+                return c
+        return (
+            cmp(self.methods, other.methods) or
+            cmp(self.constants, other.constants) or
+            cmp(self.scriptable, other.scriptable) or
+            cmp(self.function, other.function) or
+            cmp(self.builtinclass, other.builtinclass) or
+            cmp(self.main_process_scriptable_only, other.main_process_scriptable_only)
+        )
+
+    def read_descriptor(self, typelib, map, data_pool):
+        offset = self._descriptor_offset
+        if offset == 0:
+            return
+        start = data_pool + offset - 1
+        parent, num_methods = Interface._descriptorstart.unpack_from(map, start)
+        if parent > 0 and parent <= len(typelib.interfaces):
+            self.parent = typelib.interfaces[parent - 1]
+        # Read methods
+        offset += Interface._descriptorstart.size
+        for i in range(num_methods):
+            m, offset = Method.read(typelib, map, data_pool, offset)
+            self.methods.append(m)
+        # Read constants
+        start = data_pool + offset - 1
+        (num_constants, ) = struct.unpack_from(">H", map, start)
+        offset = offset + struct.calcsize(">H")
+        for i in range(num_constants):
+            c, offset = Constant.read(typelib, map, data_pool, offset)
+            self.constants.append(c)
+        # Read flags
+        start = data_pool + offset - 1
+        (flags, ) = struct.unpack_from(">B", map, start)
+        offset = offset + struct.calcsize(">B")
+        # only the first two bits are flags
+        flags &= 0xf0
+        if flags & 0x80:
+            self.scriptable = True
+        if flags & 0x40:
+            self.function = True
+        if flags & 0x20:
+            self.builtinclass = True
+        if flags & 0x10:
+            self.main_process_scriptable_only = True
+        self.resolved = True
+
+    def write_directory_entry(self, file):
+        """
+        Write an InterfaceDirectoryEntry for this interface
+        to |file|, which is assumed to be seeked to the correct offset.
+
+        """
+        file.write(Interface._direntry.pack(Typelib.string_to_iid(self.iid),
+                                            self._name_offset,
+                                            self._namespace_offset,
+                                            self._descriptor_offset))
+
+    def write(self, typelib, file, data_pool_offset):
+        """
+        Write an InterfaceDescriptor to |file|, which is assumed
+        to be seeked to the proper position. If this interface
+        is not resolved, do not write any data.
+
+        """
+        if not self.resolved:
+            self._descriptor_offset = 0
+            return
+        self._descriptor_offset = file.tell() - data_pool_offset + 1
+        parent_idx = 0
+        if self.parent:
+            parent_idx = typelib.interfaces.index(self.parent) + 1
+        file.write(Interface._descriptorstart.pack(parent_idx, len(self.methods)))
+        for m in self.methods:
+            m.write(typelib, file)
+        file.write(struct.pack(">H", len(self.constants)))
+        for c in self.constants:
+            c.write(typelib, file)
+        flags = 0
+        if self.scriptable:
+            flags |= 0x80
+        if self.function:
+            flags |= 0x40
+        if self.builtinclass:
+            flags |= 0x20
+        if self.main_process_scriptable_only:
+            flags |= 0x10
+        file.write(struct.pack(">B", flags))
+
+    def write_names(self, file, data_pool_offset):
+        """
+        Write this interface's name and namespace to |file|,
+        as well as the names of all of its methods and constants.
+        Assumes that |file| is currently seeked to an unused portion
+        of the data pool.
+
+        """
+        if self.name:
+            self._name_offset = file.tell() - data_pool_offset + 1
+            file.write(self.name + "\x00")
+        else:
+            self._name_offset = 0
+        if self.namespace:
+            self._namespace_offset = file.tell() - data_pool_offset + 1
+            file.write(self.namespace + "\x00")
+        else:
+            self._namespace_offset = 0
+        for m in self.methods:
+            m.write_name(file, data_pool_offset)
+        for c in self.constants:
+            c.write_name(file, data_pool_offset)
+
+
+class Typelib(object):
+    """
+    A typelib represents one entire typelib file and all the interfaces
+    referenced within, whether defined entirely within the typelib or
+    merely referenced by name or IID.
+
+    Typelib objects may be instantiated directly and populated with data,
+    or the static Typelib.read method may be called to read one from a file.
+
+    """
+    _header = struct.Struct(">16sBBHIII")
+
+    def __init__(self, version=TYPELIB_VERSION, interfaces=[], annotations=[]):
+        """
+        Instantiate a new Typelib.
+
+        """
+        self.version = version
+        self.interfaces = list(interfaces)
+        self.annotations = list(annotations)
+        self.filename = None
+
+    @staticmethod
+    def iid_to_string(iid):
+        """
+        Convert a 16-byte IID into a UUID string.
+
+        """
+        def hexify(s):
+            return ''.join(["%02x" % ord(x) for x in s])
+
+        return "%s-%s-%s-%s-%s" % (hexify(iid[:4]), hexify(iid[4:6]),
+                                   hexify(iid[6:8]), hexify(iid[8:10]),
+                                   hexify(iid[10:]))
+
+    @staticmethod
+    def string_to_iid(iid_str):
+        """
+        Convert a UUID string into a 16-byte IID.
+
+        """
+        s = iid_str.replace('-', '')
+        return ''.join([chr(int(s[i:i+2], 16)) for i in range(0, len(s), 2)])
+
+    @staticmethod
+    def read_string(map, data_pool, offset):
+        if offset == 0:
+            return ""
+        sz = map.find('\x00', data_pool + offset - 1)
+        if sz == -1:
+            return ""
+        return map[data_pool + offset - 1:sz]
+
+    @staticmethod
+    def read(input_file):
+        """
+        Read a typelib from |input_file| and return
+        the constructed Typelib object. |input_file| can be a filename
+        or a file-like object.
+
+        """
+        filename = ""
+        data = None
+        expected_size = None
+        if isinstance(input_file, basestring):
+            filename = input_file
+            with open(input_file, "rb") as f:
+                st = os.fstat(f.fileno())
+                data = f.read(st.st_size)
+                expected_size = st.st_size
+        else:
+            data = input_file.read()
+
+        (magic,
+         major_ver,
+         minor_ver,
+         num_interfaces,
+         file_length,
+         interface_directory_offset,
+         data_pool_offset) = Typelib._header.unpack_from(data)
+        if magic != XPT_MAGIC:
+            raise FileFormatError("Bad magic: %s" % magic)
+        xpt = Typelib((major_ver, minor_ver))
+        xpt.filename = filename
+        if expected_size and file_length != expected_size:
+            raise FileFormatError("File is of wrong length, got %d bytes, expected %d" % (expected_size, file_length))
+        # XXX: by spec this is a zero-based file offset. however,
+        # the xpt_xdr code always subtracts 1 from data offsets
+        # (because that's what you do in the data pool) so it
+        # winds up accidentally treating this as 1-based.
+        # Filed as: https://bugzilla.mozilla.org/show_bug.cgi?id=575343
+        interface_directory_offset -= 1
+        # make a half-hearted attempt to read Annotations,
+        # since XPIDL doesn't produce any anyway.
+        start = Typelib._header.size
+        (anno, ) = struct.unpack_from(">B", data, start)
+        tag = anno & 0x7F
+        if tag == 0:  # EmptyAnnotation
+            xpt.annotations.append(None)
+        # We don't bother handling PrivateAnnotations or anything
+
+        for i in range(num_interfaces):
+            # iid, name, namespace, interface_descriptor
+            start = interface_directory_offset + i * Interface._direntry.size
+            ide = Interface._direntry.unpack_from(data, start)
+            iid = Typelib.iid_to_string(ide[0])
+            name = Typelib.read_string(data, data_pool_offset, ide[1])
+            namespace = Typelib.read_string(data, data_pool_offset, ide[2])
+            iface = Interface(name, iid, namespace)
+            iface._descriptor_offset = ide[3]
+            iface.xpt_filename = xpt.filename
+            xpt.interfaces.append(iface)
+        for iface in xpt.interfaces:
+            iface.read_descriptor(xpt, data, data_pool_offset)
+        return xpt
+
+    def __repr__(self):
+        return "<Typelib with %d interfaces>" % len(self.interfaces)
+
+    def _sanityCheck(self):
+        """
+        Check certain assumptions about data contained in this typelib.
+        Sort the interfaces array by IID, check that all interfaces
+        referenced by methods exist in the array.
+
+        """
+        self.interfaces.sort()
+        for i in self.interfaces:
+            if i.parent and i.parent not in self.interfaces:
+                raise DataError("Interface %s has parent %s not present in typelib!" % (i.name, i.parent.name))
+            for m in i.methods:
+                for n, p in enumerate(m.params):
+                    if isinstance(p, InterfaceType) and \
+                       p.iface not in self.interfaces:
+                        raise DataError("Interface method %s::%s, parameter %d references interface %s not present in typelib!" % (i.name, m.name, n, p.iface.name))
+                if isinstance(m.result, InterfaceType) and m.result.iface not in self.interfaces:
+                    raise DataError("Interface method %s::%s, result references interface %s not present in typelib!" % (i.name, m.name, m.result.iface.name))
+
+    def writefd(self, fd):
+        # write out space for a header + one empty annotation,
+        # padded to 4-byte alignment.
+        headersize = (Typelib._header.size + 1)
+        if headersize % 4:
+            headersize += 4 - headersize % 4
+        fd.write("\x00" * headersize)
+        # save this offset, it's the interface directory offset.
+        interface_directory_offset = fd.tell()
+        # write out space for an interface directory
+        fd.write("\x00" * Interface._direntry.size * len(self.interfaces))
+        # save this offset, it's the data pool offset.
+        data_pool_offset = fd.tell()
+        # write out all the interface descriptors to the data pool
+        for i in self.interfaces:
+            i.write_names(fd, data_pool_offset)
+            i.write(self, fd, data_pool_offset)
+        # now, seek back and write the header
+        file_len = fd.tell()
+        fd.seek(0)
+        fd.write(Typelib._header.pack(XPT_MAGIC,
+                                      TYPELIB_VERSION[0],
+                                      TYPELIB_VERSION[1],
+                                      len(self.interfaces),
+                                      file_len,
+                                      interface_directory_offset,
+                                      data_pool_offset))
+        # write an empty annotation
+        fd.write(struct.pack(">B", 0x80))
+        # now write the interface directory
+        # XXX: bug-compatible with existing xpt lib, put it one byte
+        # ahead of where it's supposed to be.
+        fd.seek(interface_directory_offset - 1)
+        for i in self.interfaces:
+            i.write_directory_entry(fd)
+
+    def write(self, output_file):
+        """
+        Write the contents of this typelib to |output_file|,
+        which can be either a filename or a file-like object.
+
+        """
+        self._sanityCheck()
+        if isinstance(output_file, basestring):
+            with open(output_file, "wb") as f:
+                self.writefd(f)
+        else:
+            self.writefd(output_file)
+
+    def dump(self, out):
+        """
+        Print a human-readable listing of the contents of this typelib
+        to |out|, in the format of xpt_dump.
+
+        """
+        out.write("""Header:
+   Major version:         %d
+   Minor version:         %d
+   Number of interfaces:  %d
+   Annotations:\n""" % (self.version[0], self.version[1], len(self.interfaces)))
+        for i, a in enumerate(self.annotations):
+            if a is None:
+                out.write("      Annotation #%d is empty.\n" % i)
+        out.write("\nInterface Directory:\n")
+        for i in self.interfaces:
+            out.write("   - %s::%s (%s):\n" % (i.namespace, i.name, i.iid))
+            if not i.resolved:
+                out.write("      [Unresolved]\n")
+            else:
+                if i.parent:
+                    out.write("      Parent: %s::%s\n" % (i.parent.namespace,
+                                                          i.parent.name))
+                out.write("""      Flags:
+         Scriptable: %s
+         BuiltinClass: %s
+         Function: %s\n""" % (i.scriptable and "TRUE" or "FALSE",
+                              i.builtinclass and "TRUE" or "FALSE",
+                              i.function and "TRUE" or "FALSE"))
+                out.write("      Methods:\n")
+                if len(i.methods) == 0:
+                    out.write("         No Methods\n")
+                else:
+                    for m in i.methods:
+                        out.write("   %s%s%s%s%s%s%s %s %s(%s);\n" % (
+                            m.getter and "G" or " ",
+                            m.setter and "S" or " ",
+                            m.hidden and "H" or " ",
+                            m.notxpcom and "N" or " ",
+                            m.constructor and "C" or " ",
+                            m.optargc and "O" or " ",
+                            m.implicit_jscontext and "J" or " ",
+                            str(m.result.type),
+                            m.name,
+                            m.params and ", ".join(str(p) for p in m.params) or ""
+                            ))
+                out.write("      Constants:\n")
+                if len(i.constants) == 0:
+                    out.write("         No Constants\n")
+                else:
+                    for c in i.constants:
+                        out.write("         %s %s = %d;\n" % (c.type, c.name, c.value))
+
+
+def xpt_dump(file):
+    """
+    Dump the contents of |file| to stdout in the format of xpt_dump.
+
+    """
+    t = Typelib.read(file)
+    t.dump(sys.stdout)
+
+
+def xpt_link(inputs):
+    """
+    Link all of the xpt files in |inputs| together and return the result
+    as a Typelib object. All entries in inputs may be filenames or
+    file-like objects. Non-scriptable interfaces that are unreferenced
+    from scriptable interfaces will be removed during linking.
+
+    """
+    def read_input(i):
+        if isinstance(i, Typelib):
+            return i
+        return Typelib.read(i)
+
+    if not inputs:
+        print >>sys.stderr, "Usage: xpt_link <destination file> <input files>"
+        return None
+    # This is the aggregate list of interfaces.
+    interfaces = []
+    # This will be a dict of replaced interface -> replaced with
+    # containing interfaces that were replaced with interfaces from
+    # another typelib, and the interface that replaced them.
+    merged_interfaces = {}
+    for f in inputs:
+        t = read_input(f)
+        interfaces.extend(t.interfaces)
+    # Sort interfaces by name so we can merge adjacent duplicates
+    interfaces.sort(key=operator.attrgetter('name'))
+
+    Result = enum('Equal',     # Interfaces the same, doesn't matter
+                  'NotEqual',  # Interfaces differ, keep both
+                  'KeepFirst',  # Replace second interface with first
+                  'KeepSecond')  # Replace first interface with second
+
+    def compare(i, j):
+        """
+        Compare two interfaces, determine if they're equal or
+        completely different, or should be merged (and indicate which
+        one to keep in that case).
+
+        """
+        if i == j:
+            # Arbitrary, just pick one
+            return Result.Equal
+        if i.name != j.name:
+            if i.iid == j.iid and i.iid != Interface.UNRESOLVED_IID:
+                # Same IID but different names: raise an exception.
+                raise DataError(
+                    "Typelibs contain definitions of interface %s"
+                    " with different names (%s (%s) vs %s (%s))!" %
+                    (i.iid, i.name, i.xpt_filename, j.name, j.xpt_filename))
+            # Otherwise just different interfaces.
+            return Result.NotEqual
+        # Interfaces have the same name, so either they need to be merged
+        # or there's a data error. Sort out which one to keep
+        if i.resolved != j.resolved:
+            # prefer resolved interfaces over unresolved
+            if j.resolved:
+                assert i.iid == j.iid or i.iid == Interface.UNRESOLVED_IID
+                # keep j
+                return Result.KeepSecond
+            else:
+                assert i.iid == j.iid or j.iid == Interface.UNRESOLVED_IID
+                # replace j with i
+                return Result.KeepFirst
+        elif i.iid != j.iid:
+            # Prefer unresolved interfaces with valid IIDs
+            if j.iid == Interface.UNRESOLVED_IID:
+                # replace j with i
+                assert not j.resolved
+                return Result.KeepFirst
+            elif i.iid == Interface.UNRESOLVED_IID:
+                # keep j
+                assert not i.resolved
+                return Result.KeepSecond
+            else:
+                # Same name but different IIDs: raise an exception.
+                raise DataError(
+                    "Typelibs contain definitions of interface %s"
+                    " with different IIDs (%s (%s) vs %s (%s))!" %
+                               (i.name, i.iid, i.xpt_filename,
+                                j.iid, j.xpt_filename))
+        raise DataError("No idea what happened here: %s:%s (%s), %s:%s (%s)" %
+                        (i.name, i.iid, i.xpt_filename, j.name, j.iid, j.xpt_filename))
+
+    # Compare interfaces pairwise to find duplicates that should be merged.
+    i = 1
+    while i < len(interfaces):
+        res = compare(interfaces[i-1], interfaces[i])
+        if res == Result.NotEqual:
+            i += 1
+        elif res == Result.Equal:
+            # Need to drop one but it doesn't matter which
+            del interfaces[i]
+        elif res == Result.KeepFirst:
+            merged_interfaces[interfaces[i]] = interfaces[i-1]
+            del interfaces[i]
+        elif res == Result.KeepSecond:
+            merged_interfaces[interfaces[i-1]] = interfaces[i]
+            del interfaces[i-1]
+
+    # Now fixup any merged interfaces
+    def checkType(t):
+        if isinstance(t, InterfaceType) and t.iface in merged_interfaces:
+            t.iface = merged_interfaces[t.iface]
+        elif isinstance(t, ArrayType) and \
+            isinstance(t.element_type, InterfaceType) and \
+                t.element_type.iface in merged_interfaces:
+                t.element_type.iface = merged_interfaces[t.element_type.iface]
+
+    for i in interfaces:
+        # Replace parent references
+        if i.parent in merged_interfaces:
+            i.parent = merged_interfaces[i.parent]
+        for m in i.methods:
+            # Replace InterfaceType params and return values
+            checkType(m.result.type)
+            for p in m.params:
+                checkType(p.type)
+
+    # There's no need to have non-scriptable interfaces in a typelib, and
+    # removing them saves memory when typelibs are loaded.  But we can't
+    # just blindly remove all non-scriptable interfaces, since we still
+    # need to know about non-scriptable interfaces referenced from
+    # scriptable interfaces.
+    worklist = set(i for i in interfaces if i.scriptable)
+    required_interfaces = set()
+
+    def maybe_add_to_worklist(iface):
+        if iface in required_interfaces or iface in worklist:
+            return
+        worklist.add(iface)
+
+    while worklist:
+        i = worklist.pop()
+        required_interfaces.add(i)
+        if i.parent:
+            maybe_add_to_worklist(i.parent)
+        for m in i.methods:
+            if isinstance(m.result.type, InterfaceType):
+                maybe_add_to_worklist(m.result.type.iface)
+            for p in m.params:
+                if isinstance(p.type, InterfaceType):
+                    maybe_add_to_worklist(p.type.iface)
+                elif isinstance(p.type, ArrayType) and isinstance(p.type.element_type, InterfaceType):
+                    maybe_add_to_worklist(p.type.element_type.iface)
+
+    interfaces = list(required_interfaces)
+
+    # Re-sort interfaces (by IID)
+    interfaces.sort()
+    return Typelib(interfaces=interfaces)
+
+if __name__ == '__main__':
+    if len(sys.argv) < 3:
+        print >>sys.stderr, "xpt <dump|link> <files>"
+        sys.exit(1)
+    if sys.argv[1] == 'dump':
+        xpt_dump(sys.argv[2])
+    elif sys.argv[1] == 'link':
+        xpt_link(sys.argv[3:]).write(sys.argv[2])
diff --git a/xpcom/typelib/xpt/xpt_arena.cpp b/xpcom/typelib/xpt/xpt_arena.cpp
new file mode 100644
index 000000000..21be3c00b
--- /dev/null
+++ b/xpcom/typelib/xpt/xpt_arena.cpp
@@ -0,0 +1,196 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Quick arena hack for xpt. */
+
+/* XXX This exists because we don't want to drag in NSPR. It *seemed*
+*  to make more sense to write a quick and dirty arena than to clone
+*  plarena (like js/src did). This is not optimal, but it works. 
+*/
+
+#include "xpt_arena.h"
+#include "mozilla/MemoryReporting.h"
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+/****************************************************/
+
+/* Block header for each block in the arena */
+struct BLK_HDR
+{
+    BLK_HDR *next;
+};
+
+#define XPT_MIN_BLOCK_SIZE 32
+
+/* XXX this is lame. Should clone the code to do this bitwise */
+#define ALIGN_RND(s,a) ((a)==1?(s):((((s)+(a)-1)/(a))*(a)))
+
+struct XPTSubArena
+{
+    BLK_HDR *first;
+    uint8_t *next;
+    size_t   space;
+    size_t   block_size;
+};
+
+struct XPTArena
+{
+    // We have one sub-arena with 8-byte alignment for most allocations, and
+    // one with 1-byte alignment for C string allocations. The latter sub-arena
+    // avoids significant amounts of unnecessary padding between C strings.
+    XPTSubArena subarena8;
+    XPTSubArena subarena1;
+};
+
+XPT_PUBLIC_API(XPTArena *)
+XPT_NewArena(size_t block_size8, size_t block_size1)
+{
+    XPTArena *arena = static_cast<XPTArena*>(calloc(1, sizeof(XPTArena)));
+    if (arena) {
+        if (block_size8 < XPT_MIN_BLOCK_SIZE)
+            block_size8 = XPT_MIN_BLOCK_SIZE;
+        arena->subarena8.block_size = ALIGN_RND(block_size8, 8);
+
+        if (block_size1 < XPT_MIN_BLOCK_SIZE)
+            block_size1 = XPT_MIN_BLOCK_SIZE;
+        arena->subarena1.block_size = block_size1;
+    }
+    return arena;
+}
+
+static void
+DestroySubArena(XPTSubArena *subarena)
+{
+    BLK_HDR* cur = subarena->first;
+    while (cur) {
+        BLK_HDR* next = cur->next;
+        free(cur);
+        cur = next;
+    }
+}
+
+XPT_PUBLIC_API(void)
+XPT_DestroyArena(XPTArena *arena)
+{
+    DestroySubArena(&arena->subarena8);
+    DestroySubArena(&arena->subarena1);
+    free(arena);
+}
+
+/* 
+* Our alignment rule is that we always round up the size of each allocation 
+* so that the 'arena->next' pointer one will point to properly aligned space.
+*/
+
+XPT_PUBLIC_API(void *)
+XPT_ArenaCalloc(XPTArena *arena, size_t size, size_t alignment)
+{
+    if (!size)
+        return NULL;
+
+    if (!arena) {
+        XPT_ASSERT(0);
+        return NULL;
+    }
+
+    XPTSubArena *subarena;
+    if (alignment == 8) {
+        subarena = &arena->subarena8;
+    } else if (alignment == 1) {
+        subarena = &arena->subarena1;
+    } else {
+        XPT_ASSERT(0);
+        return NULL;
+    }
+
+    size_t bytes = ALIGN_RND(size, alignment);
+
+    if (bytes > subarena->space) {
+        BLK_HDR* new_block;
+        size_t block_header_size = ALIGN_RND(sizeof(BLK_HDR), alignment);
+        size_t new_space = subarena->block_size;
+
+        while (bytes > new_space - block_header_size)
+            new_space += subarena->block_size;
+
+        new_block =
+            static_cast<BLK_HDR*>(calloc(new_space / alignment, alignment));
+        if (!new_block) {
+            subarena->next = NULL;
+            subarena->space = 0;
+            return NULL;
+        }
+
+        /* link block into the list of blocks for use when we destroy */
+        new_block->next = subarena->first;
+        subarena->first = new_block;
+
+        /* set info for current block */
+        subarena->next =
+            reinterpret_cast<uint8_t*>(new_block) + block_header_size;
+        subarena->space = new_space - block_header_size;
+
+#ifdef DEBUG
+        /* mark block for corruption check */
+        memset(subarena->next, 0xcd, subarena->space);
+#endif
+    }
+
+#ifdef DEBUG
+    {
+        /* do corruption check */
+        size_t i;
+        for (i = 0; i < bytes; ++i) {
+            XPT_ASSERT(subarena->next[i] == 0xcd);
+        }
+        /* we guarantee that the block will be filled with zeros */
+        memset(subarena->next, 0, bytes);
+    }
+#endif
+
+    uint8_t* p = subarena->next;
+    subarena->next  += bytes;
+    subarena->space -= bytes;
+
+    return p;
+}
+
+/***************************************************************************/
+
+#ifdef DEBUG
+XPT_PUBLIC_API(void)
+XPT_AssertFailed(const char *s, const char *file, uint32_t lineno)
+{
+    fprintf(stderr, "Assertion failed: %s, file %s, line %d\n",
+            s, file, lineno);
+    abort();
+}        
+#endif
+
+static size_t
+SizeOfSubArenaExcludingThis(XPTSubArena *subarena, MozMallocSizeOf mallocSizeOf)
+{
+    size_t n = 0;
+
+    BLK_HDR* cur = subarena->first;
+    while (cur) {
+        BLK_HDR* next = cur->next;
+        n += mallocSizeOf(cur);
+        cur = next;
+    }
+
+    return n;
+}
+
+XPT_PUBLIC_API(size_t)
+XPT_SizeOfArenaIncludingThis(XPTArena *arena, MozMallocSizeOf mallocSizeOf)
+{
+    size_t n = mallocSizeOf(arena);
+    n += SizeOfSubArenaExcludingThis(&arena->subarena8, mallocSizeOf);
+    n += SizeOfSubArenaExcludingThis(&arena->subarena1, mallocSizeOf);
+    return n;
+}
diff --git a/xpcom/typelib/xpt/xpt_arena.h b/xpcom/typelib/xpt/xpt_arena.h
new file mode 100644
index 000000000..6ac146ffe
--- /dev/null
+++ b/xpcom/typelib/xpt/xpt_arena.h
@@ -0,0 +1,70 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Simple arena allocator for xpt (which avoids using NSPR).
+ */
+
+#ifndef __xpt_arena_h__
+#define __xpt_arena_h__
+
+#include <stdlib.h>
+#include "mozilla/Attributes.h"
+#include "mozilla/MemoryReporting.h"
+#include <stdint.h>
+
+
+/*
+ * The XPT library is statically linked: no functions are exported from
+ * shared libraries.
+ */
+#define XPT_PUBLIC_API(t)    t
+#define XPT_PUBLIC_DATA(t)   t
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * Simple Arena support. Use with caution!
+ */ 
+
+typedef struct XPTArena XPTArena;
+
+XPT_PUBLIC_API(XPTArena *)
+XPT_NewArena(size_t block_size8, size_t block_size1);
+
+XPT_PUBLIC_API(void)
+XPT_DestroyArena(XPTArena *arena);
+
+XPT_PUBLIC_API(void *)
+XPT_ArenaCalloc(XPTArena *arena, size_t size, size_t alignment);
+
+XPT_PUBLIC_API(size_t)
+XPT_SizeOfArenaIncludingThis(XPTArena *arena, MozMallocSizeOf mallocSizeOf);
+
+/* --------------------------------------------------------- */
+
+#define XPT_CALLOC8(_arena, _bytes) XPT_ArenaCalloc((_arena), (_bytes), 8)
+#define XPT_CALLOC1(_arena, _bytes) XPT_ArenaCalloc((_arena), (_bytes), 1)
+#define XPT_NEWZAP(_arena, _struct) ((_struct *) XPT_CALLOC8((_arena), sizeof(_struct)))
+
+/* --------------------------------------------------------- */
+
+#ifdef DEBUG
+XPT_PUBLIC_API(void)
+XPT_AssertFailed(const char *s, const char *file, uint32_t lineno)
+  MOZ_PRETEND_NORETURN_FOR_STATIC_ANALYSIS;
+#define XPT_ASSERT(_expr) \
+    ((_expr)?((void)0):XPT_AssertFailed(# _expr, __FILE__, __LINE__))
+#else
+#define XPT_ASSERT(_expr) ((void)0)
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __xpt_arena_h__ */
diff --git a/xpcom/typelib/xpt/xpt_struct.cpp b/xpcom/typelib/xpt/xpt_struct.cpp
new file mode 100644
index 000000000..c2e09abf0
--- /dev/null
+++ b/xpcom/typelib/xpt/xpt_struct.cpp
@@ -0,0 +1,432 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implementation of XDR routines for typelib structures. */
+
+#include "xpt_xdr.h"
+#include "xpt_struct.h"
+#include <string.h>
+#include <stdio.h>
+
+using mozilla::WrapNotNull;
+
+/***************************************************************************/
+/* Forward declarations. */
+
+static bool
+DoInterfaceDirectoryEntry(XPTArena *arena, NotNull<XPTCursor*> cursor,
+                          XPTInterfaceDirectoryEntry *ide);
+
+static bool
+DoConstDescriptor(XPTArena *arena, NotNull<XPTCursor*> cursor,
+                  XPTConstDescriptor *cd, XPTInterfaceDescriptor *id);
+
+static bool
+DoMethodDescriptor(XPTArena *arena, NotNull<XPTCursor*> cursor,
+                   XPTMethodDescriptor *md, XPTInterfaceDescriptor *id);
+
+static bool
+SkipAnnotation(NotNull<XPTCursor*> cursor, bool *isLast);
+
+static bool
+DoInterfaceDescriptor(XPTArena *arena, NotNull<XPTCursor*> outer,
+                      XPTInterfaceDescriptor **idp);
+
+static bool
+DoTypeDescriptorPrefix(XPTArena *arena, NotNull<XPTCursor*> cursor,
+                       XPTTypeDescriptorPrefix *tdp);
+
+static bool
+DoTypeDescriptor(XPTArena *arena, NotNull<XPTCursor*> cursor,
+                 XPTTypeDescriptor *td, XPTInterfaceDescriptor *id);
+
+static bool
+DoParamDescriptor(XPTArena *arena, NotNull<XPTCursor*> cursor,
+                  XPTParamDescriptor *pd, XPTInterfaceDescriptor *id);
+
+/***************************************************************************/
+
+XPT_PUBLIC_API(bool)
+XPT_DoHeader(XPTArena *arena, NotNull<XPTCursor*> cursor, XPTHeader **headerp)
+{
+    unsigned int i;
+    uint32_t file_length = 0;
+    uint32_t ide_offset;
+
+    XPTHeader* header = XPT_NEWZAP(arena, XPTHeader);
+    if (!header)
+        return false;
+    *headerp = header;
+
+    uint8_t magic[16];
+    for (i = 0; i < sizeof(magic); i++) {
+        if (!XPT_Do8(cursor, &magic[i]))
+            return false;
+    }
+
+    if (strncmp((const char*)magic, XPT_MAGIC, 16) != 0) {
+        /* Require that the header contain the proper magic */
+        fprintf(stderr,
+                "libxpt: bad magic header in input file; "
+                "found '%s', expected '%s'\n",
+                magic, XPT_MAGIC_STRING);
+        return false;
+    }
+
+    if (!XPT_Do8(cursor, &header->major_version) ||
+        !XPT_Do8(cursor, &header->minor_version)) {
+        return false;
+    }
+
+    if (header->major_version >= XPT_MAJOR_INCOMPATIBLE_VERSION) {
+        /* This file is newer than we are and set to an incompatible version
+         * number. We must set the header state thusly and return.
+         */
+        header->num_interfaces = 0;
+        return true;
+    }
+
+    if (!XPT_Do16(cursor, &header->num_interfaces) ||
+        !XPT_Do32(cursor, &file_length) ||
+        !XPT_Do32(cursor, &ide_offset)) {
+        return false;
+    }
+
+    /* 
+     * Make sure the file length reported in the header is the same size as
+     * as our buffer unless it is zero (not set) 
+     */
+    if (file_length != 0 && 
+        cursor->state->pool_allocated < file_length) {
+        fputs("libxpt: File length in header does not match actual length. File may be corrupt\n",
+            stderr);
+        return false;
+    }
+
+    uint32_t data_pool;
+    if (!XPT_Do32(cursor, &data_pool))
+        return false;
+
+    XPT_SetDataOffset(cursor->state, data_pool);
+
+    if (header->num_interfaces) {
+        size_t n = header->num_interfaces * sizeof(XPTInterfaceDirectoryEntry);
+        header->interface_directory =
+            static_cast<XPTInterfaceDirectoryEntry*>(XPT_CALLOC8(arena, n));
+        if (!header->interface_directory)
+            return false;
+    }
+
+    /*
+     * Iterate through the annotations rather than recurring, to avoid blowing
+     * the stack on large xpt files. We don't actually store annotations, we
+     * just skip over them.
+     */
+    bool isLast;
+    do {
+        if (!SkipAnnotation(cursor, &isLast))
+            return false;
+    } while (!isLast);
+
+    /* shouldn't be necessary now, but maybe later */
+    XPT_SeekTo(cursor, ide_offset);
+
+    for (i = 0; i < header->num_interfaces; i++) {
+        if (!DoInterfaceDirectoryEntry(arena, cursor,
+                                       &header->interface_directory[i]))
+            return false;
+    }
+
+    return true;
+}
+
+/* InterfaceDirectoryEntry records go in the header */
+bool
+DoInterfaceDirectoryEntry(XPTArena *arena, NotNull<XPTCursor*> cursor,
+                          XPTInterfaceDirectoryEntry *ide)
+{
+    char* dummy_name_space;
+
+    /* write the IID in our cursor space */
+    if (!XPT_DoIID(cursor, &(ide->iid)) ||
+
+        /* write the name string in the data pool, and the offset in our
+           cursor space */
+        !XPT_DoCString(arena, cursor, &(ide->name)) ||
+
+        /* don't write the name_space string in the data pool, because we don't
+         * need it. Do write the offset in our cursor space */
+        !XPT_DoCString(arena, cursor, &dummy_name_space, /* ignore = */ true) ||
+
+        /* do InterfaceDescriptors */
+        !DoInterfaceDescriptor(arena, cursor, &ide->interface_descriptor)) {
+        return false;
+    }
+
+    return true;
+}
+
+static bool
+InterfaceDescriptorAddTypes(XPTArena *arena, XPTInterfaceDescriptor *id,
+                            uint16_t num)
+{
+    XPTTypeDescriptor *old = id->additional_types;
+    XPTTypeDescriptor *new_;
+    size_t old_size = id->num_additional_types * sizeof(XPTTypeDescriptor);
+    size_t new_size = (num * sizeof(XPTTypeDescriptor)) + old_size;
+
+    /* XXX should grow in chunks to minimize alloc overhead */
+    new_ = static_cast<XPTTypeDescriptor*>(XPT_CALLOC8(arena, new_size));
+    if (!new_)
+        return false;
+    if (old) {
+        memcpy(new_, old, old_size);
+    }
+    id->additional_types = new_;
+
+    if (num + uint16_t(id->num_additional_types) > 256)
+        return false;
+
+    id->num_additional_types += num;
+    return true;
+}
+
+bool
+DoInterfaceDescriptor(XPTArena *arena, NotNull<XPTCursor*> outer,
+                      XPTInterfaceDescriptor **idp)
+{
+    XPTInterfaceDescriptor *id;
+    XPTCursor curs;
+    NotNull<XPTCursor*> cursor = WrapNotNull(&curs);
+    uint32_t i, id_sz = 0;
+
+    id = XPT_NEWZAP(arena, XPTInterfaceDescriptor);
+    if (!id)
+        return false;
+    *idp = id;
+
+    if (!XPT_MakeCursor(outer->state, XPT_DATA, id_sz, cursor))
+        return false;
+
+    if (!XPT_Do32(outer, &cursor->offset))
+        return false;
+    if (!cursor->offset) {
+        *idp = NULL;
+        return true;
+    }
+    if(!XPT_Do16(cursor, &id->parent_interface) ||
+       !XPT_Do16(cursor, &id->num_methods)) {
+        return false;
+    }
+
+    if (id->num_methods) {
+        size_t n = id->num_methods * sizeof(XPTMethodDescriptor);
+        id->method_descriptors =
+            static_cast<XPTMethodDescriptor*>(XPT_CALLOC8(arena, n));
+        if (!id->method_descriptors)
+            return false;
+    }
+
+    for (i = 0; i < id->num_methods; i++) {
+        if (!DoMethodDescriptor(arena, cursor, &id->method_descriptors[i], id))
+            return false;
+    }
+
+    if (!XPT_Do16(cursor, &id->num_constants)) {
+        return false;
+    }
+
+    if (id->num_constants) {
+        size_t n = id->num_constants * sizeof(XPTConstDescriptor);
+        id->const_descriptors =
+            static_cast<XPTConstDescriptor*>(XPT_CALLOC8(arena, n));
+        if (!id->const_descriptors)
+            return false;
+    }
+
+    for (i = 0; i < id->num_constants; i++) {
+        if (!DoConstDescriptor(arena, cursor, &id->const_descriptors[i], id)) {
+            return false;
+        }
+    }
+
+    if (!XPT_Do8(cursor, &id->flags)) {
+        return false;
+    }
+
+    return true;
+}
+
+bool
+DoConstDescriptor(XPTArena *arena, NotNull<XPTCursor*> cursor,
+                  XPTConstDescriptor *cd, XPTInterfaceDescriptor *id)
+{
+    bool ok = false;
+
+    if (!XPT_DoCString(arena, cursor, &cd->name) ||
+        !DoTypeDescriptor(arena, cursor, &cd->type, id)) {
+
+        return false;
+    }
+
+    switch(XPT_TDP_TAG(cd->type.prefix)) {
+      case TD_INT8:
+        ok = XPT_Do8(cursor, (uint8_t*) &cd->value.i8);
+        break;
+      case TD_INT16:
+        ok = XPT_Do16(cursor, (uint16_t*) &cd->value.i16);
+        break;
+      case TD_INT32:
+        ok = XPT_Do32(cursor, (uint32_t*) &cd->value.i32);
+        break;
+      case TD_INT64:
+        ok = XPT_Do64(cursor, &cd->value.i64);
+        break;
+      case TD_UINT8:
+        ok = XPT_Do8(cursor, &cd->value.ui8);
+        break;
+      case TD_UINT16:
+        ok = XPT_Do16(cursor, &cd->value.ui16);
+        break;
+      case TD_UINT32:
+        ok = XPT_Do32(cursor, &cd->value.ui32);
+        break;
+      case TD_UINT64:
+        ok = XPT_Do64(cursor, (int64_t *)&cd->value.ui64);
+        break;
+      case TD_CHAR:
+        ok = XPT_Do8(cursor, (uint8_t*) &cd->value.ch);
+        break;
+      case TD_WCHAR:
+        ok = XPT_Do16(cursor, &cd->value.wch);
+        break;
+        /* fall-through */
+      default:
+        fprintf(stderr, "illegal type!\n");
+        break;
+    }
+
+    return ok;
+
+}
+
+bool
+DoMethodDescriptor(XPTArena *arena, NotNull<XPTCursor*> cursor,
+                   XPTMethodDescriptor *md, XPTInterfaceDescriptor *id)
+{
+    int i;
+
+    if (!XPT_Do8(cursor, &md->flags) ||
+        !XPT_DoCString(arena, cursor, &md->name) ||
+        !XPT_Do8(cursor, &md->num_args))
+        return false;
+
+    if (md->num_args) {
+        size_t n = md->num_args * sizeof(XPTParamDescriptor);
+        md->params = static_cast<XPTParamDescriptor*>(XPT_CALLOC8(arena, n));
+        if (!md->params)
+            return false;
+    }
+
+    for(i = 0; i < md->num_args; i++) {
+        if (!DoParamDescriptor(arena, cursor, &md->params[i], id))
+            return false;
+    }
+
+    if (!DoParamDescriptor(arena, cursor, &md->result, id))
+        return false;
+
+    return true;
+}
+
+bool
+DoParamDescriptor(XPTArena *arena, NotNull<XPTCursor*> cursor,
+                  XPTParamDescriptor *pd, XPTInterfaceDescriptor *id)
+{
+    if (!XPT_Do8(cursor, &pd->flags) ||
+        !DoTypeDescriptor(arena, cursor, &pd->type, id))
+        return false;
+
+    return true;
+}
+
+bool
+DoTypeDescriptorPrefix(XPTArena *arena, NotNull<XPTCursor*> cursor,
+                       XPTTypeDescriptorPrefix *tdp)
+{
+    return XPT_Do8(cursor, &tdp->flags);
+}
+
+bool
+DoTypeDescriptor(XPTArena *arena, NotNull<XPTCursor*> cursor,
+                 XPTTypeDescriptor *td, XPTInterfaceDescriptor *id)
+{
+    if (!DoTypeDescriptorPrefix(arena, cursor, &td->prefix)) {
+        return false;
+    }
+
+    switch (XPT_TDP_TAG(td->prefix)) {
+      case TD_INTERFACE_TYPE:
+        uint16_t iface;
+        if (!XPT_Do16(cursor, &iface))
+            return false;
+        td->u.iface.iface_hi8 = (iface >> 8) & 0xff;
+        td->u.iface.iface_lo8 = iface & 0xff;
+        break;
+      case TD_INTERFACE_IS_TYPE:
+        if (!XPT_Do8(cursor, &td->u.interface_is.argnum))
+            return false;
+        break;
+      case TD_ARRAY: {
+        // argnum2 appears in the on-disk format but it isn't used.
+        uint8_t argnum2 = 0;
+        if (!XPT_Do8(cursor, &td->u.array.argnum) ||
+            !XPT_Do8(cursor, &argnum2))
+            return false;
+
+        if (!InterfaceDescriptorAddTypes(arena, id, 1))
+            return false;
+        td->u.array.additional_type = id->num_additional_types - 1;
+
+        if (!DoTypeDescriptor(arena, cursor,
+                              &id->additional_types[td->u.array.additional_type],
+                              id))
+            return false;
+        break;
+      }
+      case TD_PSTRING_SIZE_IS:
+      case TD_PWSTRING_SIZE_IS: {
+        // argnum2 appears in the on-disk format but it isn't used.
+        uint8_t argnum2 = 0;
+        if (!XPT_Do8(cursor, &td->u.pstring_is.argnum) ||
+            !XPT_Do8(cursor, &argnum2))
+            return false;
+        break;
+      }
+      default:
+        /* nothing special */
+        break;
+    }
+    return true;
+}
+
+bool
+SkipAnnotation(NotNull<XPTCursor*> cursor, bool *isLast)
+{
+    uint8_t flags;
+    if (!XPT_Do8(cursor, &flags))
+        return false;
+
+    *isLast = XPT_ANN_IS_LAST(flags);
+
+    if (XPT_ANN_IS_PRIVATE(flags)) {
+        if (!XPT_SkipStringInline(cursor) ||
+            !XPT_SkipStringInline(cursor))
+            return false;
+    }
+
+    return true;
+}
+
diff --git a/xpcom/typelib/xpt/xpt_struct.h b/xpcom/typelib/xpt/xpt_struct.h
new file mode 100644
index 000000000..b4da4a3fd
--- /dev/null
+++ b/xpcom/typelib/xpt/xpt_struct.h
@@ -0,0 +1,366 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Structures matching the in-memory representation of typelib structures.
+ * http://www.mozilla.org/scriptable/typelib_file.html
+ */
+
+#ifndef __xpt_struct_h__
+#define __xpt_struct_h__
+
+#include "xpt_arena.h"
+#include <stdint.h>
+
+extern "C" {
+
+/*
+ * Originally, I was going to have structures that exactly matched the on-disk
+ * representation, but that proved difficult: different compilers can pack
+ * their structs differently, and that makes overlaying them atop a
+ * read-from-disk byte buffer troublesome.  So now I just have some structures
+ * that are used in memory, and we're going to write a nice XDR library to
+ * write them to disk and stuff.  It is pure joy. -- shaver
+ */
+
+/* Structures for the typelib components */
+
+typedef struct XPTHeader XPTHeader;
+typedef struct XPTInterfaceDirectoryEntry XPTInterfaceDirectoryEntry;
+typedef struct XPTInterfaceDescriptor XPTInterfaceDescriptor;
+typedef struct XPTConstDescriptor XPTConstDescriptor;
+typedef struct XPTMethodDescriptor XPTMethodDescriptor;
+typedef struct XPTParamDescriptor XPTParamDescriptor;
+typedef struct XPTTypeDescriptor XPTTypeDescriptor;
+typedef struct XPTTypeDescriptorPrefix XPTTypeDescriptorPrefix;
+
+#ifndef nsID_h__
+/*
+ * We can't include nsID.h, because it's full of C++ goop and we're not doing
+ * C++ here, so we define our own minimal struct.  We protect against multiple
+ * definitions of this struct, though, and use the same field naming.
+ */
+struct nsID {
+    uint32_t m0;
+    uint16_t m1;
+    uint16_t m2;
+    uint8_t  m3[8];
+};
+
+typedef struct nsID nsID;
+#endif
+
+/*
+ * Every XPCOM typelib file begins with a header.
+ */
+struct XPTHeader {
+    // Some of these fields exists in the on-disk format but don't need to be
+    // stored in memory (other than very briefly, which can be done with local
+    // variables).
+
+    //uint8_t                   magic[16];
+    uint8_t                     major_version;
+    uint8_t                     minor_version;
+    uint16_t                    num_interfaces;
+    //uint32_t                  file_length;
+    XPTInterfaceDirectoryEntry  *interface_directory;
+    //uint32_t                  data_pool;
+};
+
+#define XPT_MAGIC "XPCOM\nTypeLib\r\n\032"
+/* For error messages. */
+#define XPT_MAGIC_STRING "XPCOM\\nTypeLib\\r\\n\\032"
+#define XPT_MAJOR_VERSION 0x01
+#define XPT_MINOR_VERSION 0x02
+
+/* Any file with a major version number of XPT_MAJOR_INCOMPATIBLE_VERSION
+ * or higher is to be considered incompatible by this version of xpt and
+ * we will refuse to read it. We will return a header with magic, major and
+ * minor versions set from the file. num_interfaces will be set to zero to
+ * confirm our inability to read the file; i.e. even if some client of this
+ * library gets out of sync with us regarding the agreed upon value for
+ * XPT_MAJOR_INCOMPATIBLE_VERSION, anytime num_interfaces is zero we *know*
+ * that this library refused to read the file due to version incompatibility.
+ */
+#define XPT_MAJOR_INCOMPATIBLE_VERSION 0x02
+
+/*
+ * A contiguous array of fixed-size InterfaceDirectoryEntry records begins at 
+ * the byte offset identified by the interface_directory field in the file 
+ * header.  The array is used to quickly locate an interface description 
+ * using its IID.  No interface should appear more than once in the array.
+ */
+struct XPTInterfaceDirectoryEntry {
+    nsID                   iid;
+    char                   *name;
+
+    // This field exists in the on-disk format. But it isn't used so we don't
+    // allocate space for it in memory.
+    //char                 *name_space;
+
+    XPTInterfaceDescriptor *interface_descriptor;
+};
+
+/*
+ * An InterfaceDescriptor describes a single XPCOM interface, including all of
+ * its methods.
+ */
+struct XPTInterfaceDescriptor {
+    /* This field ordering minimizes the size of this struct.
+    *  The fields are serialized on disk in a different order.
+    *  See DoInterfaceDescriptor().
+    */
+    XPTMethodDescriptor     *method_descriptors;
+    XPTConstDescriptor      *const_descriptors;
+    XPTTypeDescriptor       *additional_types;
+    uint16_t                parent_interface;
+    uint16_t                num_methods;
+    uint16_t                num_constants;
+    uint8_t                 flags;
+
+    /* additional_types are used for arrays where we may need multiple
+    *  XPTTypeDescriptors for a single XPTMethodDescriptor. Since we still
+    *  want to have a simple array of XPTMethodDescriptor (each with a single
+    *  embedded XPTTypeDescriptor), a XPTTypeDescriptor can have a reference
+    *  to an 'additional_type'. That reference is an index in this 
+    *  "additional_types" array. So a given XPTMethodDescriptor might have 
+    *  a whole chain of these XPTTypeDescriptors to represent, say, a multi
+    *  dimensional array.
+    *
+    *  Note that in the typelib file these additional types are stored 'inline'
+    *  in the MethodDescriptor. But, in the typelib MethodDescriptors can be 
+    *  of varying sizes, where in XPT's in memory mapping of the data we want 
+    *  them to be of fixed size. This additional_types scheme is here to allow 
+    *  for that.
+    */
+    uint8_t                 num_additional_types;
+};
+
+#define XPT_ID_SCRIPTABLE           0x80
+#define XPT_ID_FUNCTION             0x40
+#define XPT_ID_BUILTINCLASS         0x20
+#define XPT_ID_MAIN_PROCESS_SCRIPTABLE_ONLY 0x10
+#define XPT_ID_FLAGMASK             0xf0
+
+#define XPT_ID_IS_SCRIPTABLE(flags) (!!(flags & XPT_ID_SCRIPTABLE))
+#define XPT_ID_IS_FUNCTION(flags) (!!(flags & XPT_ID_FUNCTION))
+#define XPT_ID_IS_BUILTINCLASS(flags) (!!(flags & XPT_ID_BUILTINCLASS))
+#define XPT_ID_IS_MAIN_PROCESS_SCRIPTABLE_ONLY(flags) (!!(flags & XPT_ID_MAIN_PROCESS_SCRIPTABLE_ONLY))
+
+/* 
+ * A TypeDescriptor is a variable-size record used to identify the type of a 
+ * method argument or return value. 
+ *
+ * There are three types of TypeDescriptors:
+ *
+ * SimpleTypeDescriptor
+ * InterfaceTypeDescriptor
+ * InterfaceIsTypeDescriptor
+ *
+ * The tag field in the prefix indicates which of the variant TypeDescriptor 
+ * records is being used, and hence the way any remaining fields should be 
+ * parsed. Values from 0 to 17 refer to SimpleTypeDescriptors. The value 18 
+ * designates an InterfaceTypeDescriptor, while 19 represents an 
+ * InterfaceIsTypeDescriptor.
+ */
+
+/* why bother with a struct?  - other code relies on this being a struct */
+struct XPTTypeDescriptorPrefix {
+    uint8_t flags;
+};
+
+/* flag bits */
+
+#define XPT_TDP_FLAGMASK         0xe0
+#define XPT_TDP_TAGMASK          (~XPT_TDP_FLAGMASK)
+#define XPT_TDP_TAG(tdp)         ((tdp).flags & XPT_TDP_TAGMASK)
+
+/* 
+ * The following enum maps mnemonic names to the different numeric values 
+ * of XPTTypeDescriptor->tag.
+ */
+enum XPTTypeDescriptorTags {
+    TD_INT8              = 0,
+    TD_INT16             = 1,
+    TD_INT32             = 2,
+    TD_INT64             = 3,
+    TD_UINT8             = 4,
+    TD_UINT16            = 5,
+    TD_UINT32            = 6,
+    TD_UINT64            = 7,
+    TD_FLOAT             = 8, 
+    TD_DOUBLE            = 9,
+    TD_BOOL              = 10,  
+    TD_CHAR              = 11,  
+    TD_WCHAR             = 12, 
+    TD_VOID              = 13,  
+    TD_PNSIID            = 14,
+    TD_DOMSTRING         = 15,
+    TD_PSTRING           = 16,
+    TD_PWSTRING          = 17,
+    TD_INTERFACE_TYPE    = 18,
+    TD_INTERFACE_IS_TYPE = 19,
+    TD_ARRAY             = 20,
+    TD_PSTRING_SIZE_IS   = 21,
+    TD_PWSTRING_SIZE_IS  = 22,
+    TD_UTF8STRING        = 23,
+    TD_CSTRING           = 24,
+    TD_ASTRING           = 25,
+    TD_JSVAL             = 26
+};
+
+struct XPTTypeDescriptor {
+    XPTTypeDescriptorPrefix prefix;
+
+    // The memory layout here doesn't exactly match (for the appropriate types)
+    // the on-disk format. This is to save memory.
+    union {
+        // Used for TD_INTERFACE_IS_TYPE.
+        struct {
+            uint8_t argnum;
+        } interface_is;
+
+        // Used for TD_PSTRING_SIZE_IS, TD_PWSTRING_SIZE_IS.
+        struct {
+            uint8_t argnum;
+            //uint8_t argnum2;          // Present on disk, omitted here.
+        } pstring_is;
+
+        // Used for TD_ARRAY.
+        struct {
+            uint8_t argnum;
+            //uint8_t argnum2;          // Present on disk, omitted here.
+            uint8_t additional_type;    // uint16_t on disk, uint8_t here;
+                                        // in practice it never exceeds 20.
+        } array;
+
+        // Used for TD_INTERFACE_TYPE.
+        struct {
+            // We store the 16-bit iface value as two 8-bit values in order to
+            // avoid 16-bit alignment requirements for XPTTypeDescriptor, which
+            // reduces its size and also the size of XPTParamDescriptor.
+            uint8_t iface_hi8;
+            uint8_t iface_lo8;
+        } iface;
+    } u;
+};
+
+/*
+ * A ConstDescriptor is a variable-size record that records the name and 
+ * value of a scoped interface constant. 
+ *
+ * The types of the method parameter are restricted to the following subset 
+ * of TypeDescriptors: 
+ *
+ * int8_t, uint8_t, int16_t, uint16_t, int32_t, uint32_t, 
+ * int64_t, uint64_t, wchar_t, char
+ * 
+ * The type (and thus the size) of the value record is determined by the 
+ * contents of the associated TypeDescriptor record. For instance, if type 
+ * corresponds to int16_t, then value is a two-byte record consisting of a 
+ * 16-bit signed integer.
+ */
+union XPTConstValue {
+    int8_t    i8;
+    uint8_t   ui8; 
+    int16_t   i16; 
+    uint16_t  ui16;
+    int32_t   i32; 
+    uint32_t  ui32;
+    int64_t   i64; 
+    uint64_t  ui64; 
+    char      ch; 
+    uint16_t  wch;
+}; /* varies according to type */
+
+struct XPTConstDescriptor {
+    char                *name;
+    XPTTypeDescriptor   type;
+    union XPTConstValue value;
+};
+
+/*
+ * A ParamDescriptor is a variable-size record used to describe either a 
+ * single argument to a method or a method's result.
+ */
+struct XPTParamDescriptor {
+    uint8_t           flags;
+    XPTTypeDescriptor type;
+};
+
+/* flag bits */
+#define XPT_PD_IN       0x80
+#define XPT_PD_OUT      0x40
+#define XPT_PD_RETVAL   0x20
+#define XPT_PD_SHARED   0x10
+#define XPT_PD_DIPPER   0x08
+#define XPT_PD_OPTIONAL 0x04
+#define XPT_PD_FLAGMASK 0xfc
+
+#define XPT_PD_IS_IN(flags)     (flags & XPT_PD_IN)
+#define XPT_PD_IS_OUT(flags)    (flags & XPT_PD_OUT)
+#define XPT_PD_IS_RETVAL(flags) (flags & XPT_PD_RETVAL)
+#define XPT_PD_IS_SHARED(flags) (flags & XPT_PD_SHARED)
+#define XPT_PD_IS_DIPPER(flags) (flags & XPT_PD_DIPPER)
+#define XPT_PD_IS_OPTIONAL(flags) (flags & XPT_PD_OPTIONAL)
+
+/*
+ * A MethodDescriptor is a variable-size record used to describe a single 
+ * interface method.
+ */
+struct XPTMethodDescriptor {
+    char                *name;
+    XPTParamDescriptor  *params;
+    XPTParamDescriptor  result;
+    uint8_t             flags;
+    uint8_t             num_args;
+};
+
+/* flag bits */
+#define XPT_MD_GETTER   0x80
+#define XPT_MD_SETTER   0x40
+#define XPT_MD_NOTXPCOM 0x20
+#define XPT_MD_HIDDEN   0x08
+#define XPT_MD_OPT_ARGC 0x04
+#define XPT_MD_CONTEXT  0x02
+#define XPT_MD_FLAGMASK 0xfe
+
+#define XPT_MD_IS_GETTER(flags)      (flags & XPT_MD_GETTER)
+#define XPT_MD_IS_SETTER(flags)      (flags & XPT_MD_SETTER)
+#define XPT_MD_IS_NOTXPCOM(flags)    (flags & XPT_MD_NOTXPCOM)
+#define XPT_MD_IS_HIDDEN(flags)      (flags & XPT_MD_HIDDEN)
+#define XPT_MD_WANTS_OPT_ARGC(flags) (flags & XPT_MD_OPT_ARGC)
+#define XPT_MD_WANTS_CONTEXT(flags)  (flags & XPT_MD_CONTEXT)
+
+/*
+ * Annotation records are variable-size records used to store secondary 
+ * information about the typelib, e.g. such as the name of the tool that 
+ * generated the typelib file, the date it was generated, etc.  The 
+ * information is stored with very loose format requirements so as to 
+ * allow virtually any private data to be stored in the typelib.
+ *
+ * There are two types of Annotations:
+ *
+ * EmptyAnnotation
+ * PrivateAnnotation
+ *
+ * The tag field of the prefix discriminates among the variant record 
+ * types for Annotation's.  If the tag is 0, this record is an 
+ * EmptyAnnotation. EmptyAnnotation's are ignored - they're only used to 
+ * indicate an array of Annotation's that's completely empty.  If the tag 
+ * is 1, the record is a PrivateAnnotation. 
+ *
+ * We don't actually store annotations; we just skip over them if they are
+ * present.
+ */
+
+#define XPT_ANN_LAST	                0x80
+#define XPT_ANN_IS_LAST(flags)          (flags & XPT_ANN_LAST)
+#define XPT_ANN_PRIVATE                 0x40
+#define XPT_ANN_IS_PRIVATE(flags)       (flags & XPT_ANN_PRIVATE)
+
+}
+
+#endif /* __xpt_struct_h__ */
diff --git a/xpcom/typelib/xpt/xpt_xdr.cpp b/xpcom/typelib/xpt/xpt_xdr.cpp
new file mode 100644
index 000000000..04b90422a
--- /dev/null
+++ b/xpcom/typelib/xpt/xpt_xdr.cpp
@@ -0,0 +1,227 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implementation of XDR primitives. */
+
+#include "xpt_xdr.h"
+#include "nscore.h"
+#include <string.h>             /* strchr */
+#include "mozilla/EndianUtils.h"
+
+#define CURS_POOL_OFFSET_RAW(cursor)                                          \
+  ((cursor)->pool == XPT_HEADER                                               \
+   ? (cursor)->offset                                                         \
+   : (XPT_ASSERT((cursor)->state->data_offset),                               \
+      (cursor)->offset + (cursor)->state->data_offset))
+
+#define CURS_POOL_OFFSET(cursor)                                              \
+  (CURS_POOL_OFFSET_RAW(cursor) - 1)
+
+/* can be used as lvalue */
+#define CURS_POINT(cursor)                                                    \
+  ((cursor)->state->pool_data[CURS_POOL_OFFSET(cursor)])
+
+static bool
+CHECK_COUNT(NotNull<XPTCursor*> cursor, uint32_t space)
+{
+    // Fail if we're in the data area and about to exceed the allocation.
+    // XXX Also fail if we're in the data area and !state->data_offset
+    if (cursor->pool == XPT_DATA &&
+        (CURS_POOL_OFFSET(cursor) + space > (cursor)->state->pool_allocated)) {
+        XPT_ASSERT(0);
+        fprintf(stderr, "FATAL: no room for %d in cursor\n", space);
+        return false;
+    }
+
+    return true;
+}
+
+XPT_PUBLIC_API(void)
+XPT_InitXDRState(XPTState* state, char *data, uint32_t len)
+{
+    state->next_cursor[0] = state->next_cursor[1] = 1;
+    state->pool_data = data;
+    state->pool_allocated = len;
+}
+
+/* All offsets are 1-based */
+XPT_PUBLIC_API(void)
+XPT_SetDataOffset(XPTState *state, uint32_t data_offset)
+{
+   state->data_offset = data_offset;
+}
+
+XPT_PUBLIC_API(bool)
+XPT_MakeCursor(XPTState *state, XPTPool pool, uint32_t len,
+               NotNull<XPTCursor*> cursor)
+{
+    cursor->state = state;
+    cursor->pool = pool;
+    cursor->bits = 0;
+    cursor->offset = state->next_cursor[pool];
+
+    if (!(CHECK_COUNT(cursor, len)))
+        return false;
+
+    /* this check should be in CHECK_CURSOR */
+    if (pool == XPT_DATA && !state->data_offset) {
+        fprintf(stderr, "no data offset for XPT_DATA cursor!\n");
+        return false;
+    }
+
+    state->next_cursor[pool] += len;
+
+    return true;
+}
+
+XPT_PUBLIC_API(bool)
+XPT_SeekTo(NotNull<XPTCursor*> cursor, uint32_t offset)
+{
+    /* XXX do some real checking and update len and stuff */
+    cursor->offset = offset;
+    return true;
+}
+
+XPT_PUBLIC_API(bool)
+XPT_SkipStringInline(NotNull<XPTCursor*> cursor)
+{
+    uint16_t length;
+    if (!XPT_Do16(cursor, &length))
+        return false;
+
+    uint8_t byte;
+    for (uint16_t i = 0; i < length; i++)
+        if (!XPT_Do8(cursor, &byte))
+            return false;
+
+    return true;
+}
+
+XPT_PUBLIC_API(bool)
+XPT_DoCString(XPTArena *arena, NotNull<XPTCursor*> cursor, char **identp,
+              bool ignore)
+{
+    uint32_t offset = 0;
+    if (!XPT_Do32(cursor, &offset))
+        return false;
+
+    if (!offset) {
+        *identp = NULL;
+        return true;
+    }
+
+    XPTCursor my_cursor;
+    my_cursor.pool = XPT_DATA;
+    my_cursor.offset = offset;
+    my_cursor.state = cursor->state;
+    char* start = &CURS_POINT(&my_cursor);
+
+    char* end = strchr(start, 0); /* find the end of the string */
+    if (!end) {
+        fprintf(stderr, "didn't find end of string on decode!\n");
+        return false;
+    }
+    int len = end - start;
+    XPT_ASSERT(len > 0);
+
+    if (!ignore) {
+        char *ident = (char*)XPT_CALLOC1(arena, len + 1u);
+        if (!ident)
+            return false;
+
+        memcpy(ident, start, (size_t)len);
+        ident[len] = 0;
+        *identp = ident;
+    }
+
+    return true;
+}
+
+/*
+ * IIDs are written in struct order, in the usual big-endian way.  From the
+ * typelib file spec:
+ *
+ *   "For example, this IID:
+ *     {00112233-4455-6677-8899-aabbccddeeff}
+ *   is converted to the 128-bit value
+ *     0x00112233445566778899aabbccddeeff
+ *   Note that the byte storage order corresponds to the layout of the nsIID
+ *   C-struct on a big-endian architecture."
+ *
+ * (http://www.mozilla.org/scriptable/typelib_file.html#iid)
+ */
+XPT_PUBLIC_API(bool)
+XPT_DoIID(NotNull<XPTCursor*> cursor, nsID *iidp)
+{
+    int i;
+
+    if (!XPT_Do32(cursor, &iidp->m0) ||
+        !XPT_Do16(cursor, &iidp->m1) ||
+        !XPT_Do16(cursor, &iidp->m2))
+        return false;
+
+    for (i = 0; i < 8; i++)
+        if (!XPT_Do8(cursor, (uint8_t *)&iidp->m3[i]))
+            return false;
+
+    return true;
+}
+
+// MSVC apparently cannot handle functions as template parameters very well,
+// so we need to use a macro approach here.
+
+#define XPT_DOINT(T, func, valuep)                \
+    do {                                          \
+        const size_t sz = sizeof(T);              \
+                                                  \
+        if (!CHECK_COUNT(cursor, sz)) {           \
+            return false;                         \
+        }                                         \
+                                                  \
+        *valuep = func(&CURS_POINT(cursor));      \
+        cursor->offset += sz;                     \
+        return true;                              \
+    } while(0)
+
+XPT_PUBLIC_API(bool)
+XPT_Do64(NotNull<XPTCursor*> cursor, int64_t *u64p)
+{
+    XPT_DOINT(int64_t, mozilla::BigEndian::readInt64, u64p);
+}
+
+/*
+ * When we're handling 32- or 16-bit quantities, we handle a byte at a time to
+ * avoid alignment issues.  Someone could come and optimize this to detect
+ * well-aligned cases and do a single store, if they cared.  I might care
+ * later.
+ */
+XPT_PUBLIC_API(bool)
+XPT_Do32(NotNull<XPTCursor*> cursor, uint32_t *u32p)
+{
+    XPT_DOINT(uint32_t, mozilla::BigEndian::readUint32, u32p);
+}
+
+XPT_PUBLIC_API(bool)
+XPT_Do16(NotNull<XPTCursor*> cursor, uint16_t *u16p)
+{
+    XPT_DOINT(uint16_t, mozilla::BigEndian::readUint16, u16p);
+}
+
+#undef XPT_DOINT
+
+XPT_PUBLIC_API(bool)
+XPT_Do8(NotNull<XPTCursor*> cursor, uint8_t *u8p)
+{
+    if (!CHECK_COUNT(cursor, 1))
+        return false;
+
+    *u8p = CURS_POINT(cursor);
+
+    cursor->offset++;
+
+    return true;
+}
+
+
diff --git a/xpcom/typelib/xpt/xpt_xdr.h b/xpcom/typelib/xpt/xpt_xdr.h
new file mode 100644
index 000000000..7bf23aa40
--- /dev/null
+++ b/xpcom/typelib/xpt/xpt_xdr.h
@@ -0,0 +1,86 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Basic APIs for streaming typelib structures from disk.
+ */
+
+#ifndef __xpt_xdr_h__
+#define __xpt_xdr_h__
+
+#include "xpt_struct.h"
+#include "mozilla/NotNull.h"
+
+using mozilla::NotNull;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct XPTState         XPTState;
+typedef struct XPTCursor        XPTCursor;
+
+extern XPT_PUBLIC_API(bool)
+XPT_SkipStringInline(NotNull<XPTCursor*> cursor);
+
+extern XPT_PUBLIC_API(bool)
+XPT_DoCString(XPTArena *arena, NotNull<XPTCursor*> cursor, char **strp,
+              bool ignore = false);
+
+extern XPT_PUBLIC_API(bool)
+XPT_DoIID(NotNull<XPTCursor*> cursor, nsID *iidp);
+
+extern XPT_PUBLIC_API(bool)
+XPT_Do64(NotNull<XPTCursor*> cursor, int64_t *u64p);
+
+extern XPT_PUBLIC_API(bool)
+XPT_Do32(NotNull<XPTCursor*> cursor, uint32_t *u32p);
+
+extern XPT_PUBLIC_API(bool)
+XPT_Do16(NotNull<XPTCursor*> cursor, uint16_t *u16p);
+
+extern XPT_PUBLIC_API(bool)
+XPT_Do8(NotNull<XPTCursor*> cursor, uint8_t *u8p);
+
+extern XPT_PUBLIC_API(bool)
+XPT_DoHeader(XPTArena *arena, NotNull<XPTCursor*> cursor, XPTHeader **headerp);
+
+typedef enum {
+    XPT_HEADER = 0,
+    XPT_DATA = 1
+} XPTPool;
+
+struct XPTState {
+    uint32_t         data_offset;
+    uint32_t         next_cursor[2];
+    char             *pool_data;
+    uint32_t         pool_allocated;
+};
+
+struct XPTCursor {
+    XPTState    *state;
+    XPTPool     pool;
+    uint32_t    offset;
+    uint8_t     bits;
+};
+
+extern XPT_PUBLIC_API(void)
+XPT_InitXDRState(XPTState* state, char* data, uint32_t len);
+
+extern XPT_PUBLIC_API(bool)
+XPT_MakeCursor(XPTState *state, XPTPool pool, uint32_t len,
+               NotNull<XPTCursor*> cursor);
+
+extern XPT_PUBLIC_API(bool)
+XPT_SeekTo(NotNull<XPTCursor*> cursor, uint32_t offset);
+
+extern XPT_PUBLIC_API(void)
+XPT_SetDataOffset(XPTState *state, uint32_t data_offset);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __xpt_xdr_h__ */
diff --git a/xpcom/windbgdlg/Makefile.in b/xpcom/windbgdlg/Makefile.in
new file mode 100644
index 000000000..254509ee7
--- /dev/null
+++ b/xpcom/windbgdlg/Makefile.in
@@ -0,0 +1,6 @@
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+MOZ_WINCONSOLE = 0
diff --git a/xpcom/windbgdlg/moz.build b/xpcom/windbgdlg/moz.build
new file mode 100644
index 000000000..f0343d31a
--- /dev/null
+++ b/xpcom/windbgdlg/moz.build
@@ -0,0 +1,9 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+SimplePrograms([
+    'windbgdlg'
+])
diff --git a/xpcom/windbgdlg/windbgdlg.cpp b/xpcom/windbgdlg/windbgdlg.cpp
new file mode 100644
index 000000000..a51fe134f
--- /dev/null
+++ b/xpcom/windbgdlg/windbgdlg.cpp
@@ -0,0 +1,121 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Windows only app to show a modal debug dialog - launched by nsDebug.cpp */
+#include <windows.h>
+#include <stdlib.h>
+#ifdef _MSC_VER
+#include <strsafe.h>
+#endif
+#ifdef __MINGW32__
+/* MingW currently does not implement a wide version of the
+   startup routines.  Workaround is to implement something like
+   it ourselves.  See bug 472063 */
+#include <stdio.h>
+#include <shellapi.h>
+int WINAPI wWinMain(HINSTANCE, HINSTANCE, LPWSTR, int);
+
+#undef __argc
+#undef __wargv
+
+static int __argc;
+static wchar_t** __wargv;
+
+int WINAPI
+WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
+        LPSTR lpszCommandLine, int nCmdShow)
+{
+  LPWSTR commandLine = GetCommandLineW();
+
+  /* parse for __argc and __wargv for compatibility, since mingw
+   * doesn't claim to support it :(
+   */
+  __wargv = CommandLineToArgvW(commandLine, &__argc);
+  if (!__wargv)
+    return 127;
+
+  /* need to strip off any leading whitespace plus the first argument
+   * (the executable itself) to match what should be passed to wWinMain
+   */
+  while ((*commandLine <= L' ') && *commandLine) {
+    ++commandLine;
+  }
+  if (*commandLine == L'"') {
+    ++commandLine;
+    while ((*commandLine != L'"') && *commandLine) {
+      ++commandLine;
+    }
+    if (*commandLine) {
+      ++commandLine;
+    }
+  } else {
+    while (*commandLine > L' ') {
+      ++commandLine;
+    }
+  }
+  while ((*commandLine <= L' ') && *commandLine) {
+    ++commandLine;
+  }
+
+  int result = wWinMain(hInstance, hPrevInstance, commandLine, nCmdShow);
+  LocalFree(__wargv);
+  return result;
+}
+#endif /* __MINGW32__ */
+
+
+int WINAPI
+wWinMain(HINSTANCE  hInstance, HINSTANCE  hPrevInstance,
+         LPWSTR  lpszCmdLine, int  nCmdShow)
+{
+  /* support for auto answering based on words in the assertion.
+   * the assertion message is sent as a series of arguements (words) to the commandline.
+   * set a "word" to 0xffffffff to let the word not affect this code.
+   * set a "word" to 0xfffffffe to show the dialog.
+   * set a "word" to 0x5 to ignore (program should continue).
+   * set a "word" to 0x4 to retry (should fall into debugger).
+   * set a "word" to 0x3 to abort (die).
+   */
+  DWORD regType;
+  DWORD regValue = -1;
+  DWORD regLength = sizeof regValue;
+  HKEY hkeyCU, hkeyLM;
+  RegOpenKeyExW(HKEY_CURRENT_USER, L"Software\\mozilla.org\\windbgdlg", 0, KEY_READ, &hkeyCU);
+  RegOpenKeyExW(HKEY_LOCAL_MACHINE, L"Software\\mozilla.org\\windbgdlg", 0, KEY_READ, &hkeyLM);
+  int argc =0;
+  for (int i = __argc - 1; regValue == (DWORD)-1 && i; --i) {
+    bool ok = false;
+    if (hkeyCU)
+      ok = RegQueryValueExW(hkeyCU, __wargv[i], 0, &regType, (LPBYTE)&regValue, &regLength) == ERROR_SUCCESS;
+    if (!ok && hkeyLM)
+      ok = RegQueryValueExW(hkeyLM, __wargv[i], 0, &regType, (LPBYTE)&regValue, &regLength) == ERROR_SUCCESS;
+    if (!ok)
+      regValue = -1;
+  }
+  if (hkeyCU)
+    RegCloseKey(hkeyCU);
+  if (hkeyLM)
+    RegCloseKey(hkeyLM);
+  if (regValue != (DWORD)-1 && regValue != (DWORD)-2)
+    return regValue;
+  static const int size = 4096;
+  static WCHAR msg[size];
+
+#ifdef _MSC_VER
+  StringCchPrintfW(msg,
+#else
+  snwprintf(msg,
+#endif
+            size,
+            L"%s\n\nClick Abort to exit the Application.\n"
+            L"Click Retry to Debug the Application.\n"
+            L"Click Ignore to continue running the Application.",
+            lpszCmdLine);
+  msg[size - 1] = L'\0';
+  return MessageBoxW(nullptr, msg, L"NSGlue_Assertion",
+                     MB_ICONSTOP | MB_SYSTEMMODAL |
+                     MB_ABORTRETRYIGNORE | MB_DEFBUTTON3);
+}
diff --git a/xpcom/xpcom-config.h.in b/xpcom/xpcom-config.h.in
new file mode 100644
index 000000000..7b2de5025
--- /dev/null
+++ b/xpcom/xpcom-config.h.in
@@ -0,0 +1,24 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Global defines needed by xpcom clients */
+
+#ifndef _XPCOM_CONFIG_H_
+#define _XPCOM_CONFIG_H_
+
+/* Define this to throw() if the compiler complains about 
+ * constructors returning NULL
+ */
+#undef CPP_THROW_NEW
+
+/* Define if the c++ compiler can resolve ambiguity with |using| */
+#undef HAVE_CPP_AMBIGUITY_RESOLVING_USING
+
+/* Define if a dyanmic_cast to void* gives the most derived object */
+#undef HAVE_CPP_DYNAMIC_CAST_TO_VOID_PTR
+
+/* Define to a string describing the XPCOM ABI in use */
+#undef TARGET_XPCOM_ABI
+
+#endif /* _XPCOM_CONFIG_H_ */
diff --git a/xpcom/xpcom-private.h.in b/xpcom/xpcom-private.h.in
new file mode 100644
index 000000000..66c024fd8
--- /dev/null
+++ b/xpcom/xpcom-private.h.in
@@ -0,0 +1,50 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* The following defines are only used by the xpcom implementation */
+
+#ifndef _XPCOM_PRIVATE_H_
+#define _XPCOM_PRIVATE_H_
+
+/* Define if getpagesize() is available */
+#undef HAVE_GETPAGESIZE
+
+/* Define if iconv() is available */
+#undef HAVE_ICONV
+
+/* Define if iconv() supports const input */
+#undef HAVE_ICONV_WITH_CONST_INPUT
+
+/* Define if mbrtowc() is available */
+#undef HAVE_MBRTOWC
+
+/* Define if wcrtomb() is available */
+#undef HAVE_WCRTOMB
+
+/* Define if statvfs64() is available */
+#undef HAVE_STATVFS64
+
+/* Define if statvfs() is available */
+#undef HAVE_STATVFS
+
+/* Define if statfs64() is available */
+#undef HAVE_STATFS64
+
+/* Define if statfs() is available */
+#undef HAVE_STATFS
+
+/* Define if <sys/statvfs.h> is present */
+#undef HAVE_SYS_STATVFS_H
+
+/* Define if <sys/statfs.h> is present */
+#undef HAVE_SYS_STATFS_H
+
+/* Define if <sys/vfs.h> is present */
+#undef HAVE_SYS_VFS_H
+
+/* Define if <sys/mount.h> is present */
+#undef HAVE_SYS_MOUNT_H
+
+#endif /* _XPCOM_PRIVATE_H_ */
+
diff --git a/xpcom/xpidl/Makefile.in b/xpcom/xpidl/Makefile.in
new file mode 100644
index 000000000..b58ad4866
--- /dev/null
+++ b/xpcom/xpidl/Makefile.in
@@ -0,0 +1,10 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+export::
+	$(call py_action,process_install_manifest,$(DIST)/idl $(DEPTH)/_build_manifests/install/dist_idl)
+	$(call SUBMAKE,xpidl,$(DEPTH)/config/makefiles/xpidl)
+
+clean clobber realclean clobber_all distclean::
+	$(call SUBMAKE,$@,$(DEPTH)/config/makefiles/xpidl)
diff --git a/xpcom/xpidl/moz.build b/xpcom/xpidl/moz.build
new file mode 100644
index 000000000..568f361a5
--- /dev/null
+++ b/xpcom/xpidl/moz.build
@@ -0,0 +1,5 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.